阅读说明：本技术 注水泵 (Water injection pump ) 是由 柿元泰 松田力 青田昭仁 于 2019-09-20 设计创作，主要内容包括：作为本发明的一方式的注水泵,具备：水排出通路,该水排出通路构成为与注水管连通,该注水管与气缸的燃料喷射阀连接；水活塞部,该水活塞部对水排出通路内的水加压并向燃料喷射阀侧排出；安全阀,该安全阀沿着水活塞部的活塞轴配置于水排出通路与注水管之间,并且具有与注水管相通的内部通路；以及排液通路,该排液通路从安全阀通向注水泵外部。安全阀使内部通路成为相对于排液通路封闭的闭状态,从而将由水活塞部加压了的水从水排出通路通过内部通路而导向注水管,该内部通路通过从燃料喷射阀的压力而成为开状态,从而将逆流液体引导为从内部通路通过排液通路向注水泵外部排出。(A water injection pump according to an aspect of the present invention includes: a water discharge passage configured to communicate with a water injection pipe connected to a fuel injection valve of a cylinder; a water piston portion that pressurizes water in the water discharge passage and discharges the water to the fuel injection valve side; a safety valve disposed between the water discharge passage and the water filling pipe along a piston shaft of the water piston portion and having an internal passage communicating with the water filling pipe; and a drain passage leading from the safety valve to the outside of the water injection pump. The safety valve closes the internal passage from the drain passage, and guides the water pressurized by the water piston from the water discharge passage to the water filling pipe through the internal passage, and the internal passage opens by the pressure from the fuel injection valve, and guides the reverse flow liquid from the internal passage to the outside of the water filling pump through the drain passage.)

1. A water injection pump is characterized by comprising:

a water discharge passage configured to communicate with a water injection pipe connected to a fuel injection valve of a cylinder;

a water piston portion that is provided so as to be capable of reciprocating in the water discharge passage, and that pressurizes and discharges water in the water discharge passage to the fuel injection valve side;

a safety valve disposed between the water discharge passage and the water filling pipe along a piston shaft of the water piston portion, and having an internal passage communicating with the water filling pipe; and

a drain passage leading from the safety valve to the outside of the water injection pump,

the safety valve closes the internal passage to the drain passage, and guides the water pressurized by the water piston from the water discharge passage to the water injection pipe through the internal passage,

the safety valve opens the internal passage to the drain passage by the pressure of the reverse flow liquid flowing back from the fuel injection valve to the internal passage through the water injection pipe, and guides the reverse flow liquid to be discharged from the internal passage to the outside of the water injection pump through the drain passage.

2. The water injection pump according to claim 1, comprising:

and a discharge check valve disposed between the safety valve and the water discharge passage along a piston shaft of the water piston portion, and restricting a flow direction of water discharged from the water discharge passage to a direction from the water discharge passage side toward the safety valve side.

3. The water injection pump according to claim 1 or 2, comprising:

and a water supply check valve disposed between the safety valve and the water discharge passage along a piston shaft of the water piston portion, and configured to be switched between an open state in which a flow of water supplied into the water discharge passage through a water supply pipe is permitted and a closed state in which a reverse flow of water from the water discharge passage side to the water supply pipe side is prevented and a flow of water discharged from the water discharge passage to the safety valve side is permitted.

4. Water injection pump according to one of the claims 1 to 3,

a plurality of the water discharge passages, a plurality of the water piston portions, and a plurality of the safety valves are provided,

the plurality of water discharge passages are configured to communicate with the plurality of fuel injection valves provided in one of the cylinders through the plurality of water injection pipes,

a plurality of the water piston portions are provided in the plurality of water discharge passages so as to be capable of reciprocating,

the plurality of safety valves are disposed along the respective piston axes of the plurality of water piston portions on the side of the plurality of water injection pipes with respect to the plurality of water discharge passages.

5. The water injection pump of claim 4,

the liquid discharge passage is composed of the following passages:

a plurality of branch passages communicating with the plurality of relief valves, respectively; and

a merging passage that merges with the plurality of branch passages and communicates with the outside of the water injection pump.

6. The water injection pump according to any one of claims 1 to 5, comprising:

a water tank having the water discharge passage and the water piston portion inside thereof; and

a safety valve block having the safety valve and the liquid discharge passage inside,

the safety valve block is detachably mounted on the upper portion of the water tank by a fastening member.

7. The water injection pump according to claim 6 when dependent on claim 2 or 3, comprising:

a discharge check valve block disposed between the safety valve block and the water tank, the discharge check valve block having the discharge check valve therein; and

a water supply check valve block disposed between the discharge check valve block and the water tank, the water supply check valve block having the water supply check valve therein,

the water supply check valve block, the discharge check valve block, and the safety valve block are detachably mounted on the upper portion of the water tub by the fastening member.

Technical Field

The invention relates to a water injection pump.

Background

In a marine diesel engine mounted on a ship, water technology has been proposed as a method for reducing nitrogen oxides (NOx) in exhaust gas discharged from a combustion chamber in a cylinder. In this water technology, for example, fuel and water are added to the combustion chamber from a fuel injection valve provided in the cylinder, so that the temperature rise of flame when the fuel is combusted in the combustion chamber is suppressed, and as a result, the amount of NOx discharged from the combustion chamber is reduced. In such a water technique, a hydraulically driven water injection pump that utilizes the pressure of hydraulic oil is used to inject water into fuel present in a fuel passage in a fuel injection valve during a period other than an injection period during which fuel is injected into a combustion chamber (hereinafter, referred to as an injection suspension period). As an example of the hydraulically driven water injection pump, patent document 1 discloses a water injection piston device. Hereinafter, the water injection pump is a hydraulically driven water injection pump exemplified in the water injection piston device.

In the diesel engine described in patent document 1, one fuel injection valve is provided in one cylinder, and fuel and water are injected from the one fuel injection valve into a combustion chamber in the cylinder. Subsequently, during the injection suspension period, the fuel to be injected next remains in the fuel passage in the fuel injection valve. The water injection pump is generally configured to communicate with the fuel passage in the fuel injection valve via a water injection pipe or the like. During the injection suspension period, the water injection pump injects water into the fuel in the fuel passage through a water injection pipe or the like by pressurizing and delivering water at a pressure higher than the pressure of the fuel remaining in the fuel passage (hereinafter referred to as a residual fuel pressure). The fuel and the water in the fuel passage are injected from the fuel injection valve into the combustion chamber in the next injection period after the injection suspension period.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4550991

Technical problem to be solved by the invention

Generally, an in-fuel-valve check valve described in patent document 1, for example, is provided between a connection end portion of a fuel passage and a water injection pipe in the fuel injection valve to prevent a high-pressure fuel injected into a combustion chamber from the fuel injection valve from flowing backward from the fuel passage to the water injection pipe side. Further, a water injection check valve described in patent document 1, for example, is provided in a water injection pipe that communicates the fuel injection valve and the water injection pump, so as to prevent backflow of water discharged from the water injection pump to the fuel injection valve.

However, when the check valve and the water injection check valve do not function for some reason such as a failure in the fuel valve during injection of fuel and water into the combustion chamber, there is a concern that: the high-pressure fuel flows backward from the fuel passage in the fuel injection valve into the water injection pipe through the fuel valve check valve, and finally, an excessively high pressure is applied to the water injection pump through the water injection pipe. Here, the pressure-resistant structure of the water injection pump is designed to be able to receive the discharge pressure of water (for example, about 200 to 300 bar). In contrast, the pressure of the fuel flowing backward from the fuel injection valve (for example, about 800 to 1200bar equal to the injection pressure of the fuel injected from the fuel injection valve) is much higher than the pressure that can be received by the pressure-resistant structure of the water injection pump, and is not the pressure that can be received by the water injection pump. Therefore, when the high-pressure fuel flows back from the fuel injection valve to the water injection pipe, there is a concern that: the water injection pump is damaged by the pressure of the fuel flowing backward, and the fuel leaks from the water injection pump.

The pressure-resistant structure of the water injection pump can be strengthened to a structure capable of withstanding the pressure of the fuel flowing back by a method such as increasing the thickness of the flow path of the discharged water. However, the strengthening of the pressure-resistant structure is associated with the enlargement of the water injection pump, and it is difficult to dispose the water injection pump having such an enlargement in a limited space around the cylinder of the marine diesel engine. Therefore, from the viewpoint of securing the arrangement space of the water injection pump, it is preferable that the water injection pump be miniaturized.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a water injection pump capable of avoiding excessive pressurization due to a reverse flow liquid such as fuel that flows back from a fuel injection valve, and achieving downsizing of the device scale.

Means for solving the problems

In order to solve the above-described problems and achieve the object, a water injection pump according to the present invention includes: a water discharge passage configured to communicate with a water injection pipe connected to a fuel injection valve of a cylinder; a water piston portion that is provided so as to be capable of reciprocating in the water discharge passage, and that pressurizes and discharges water in the water discharge passage to the fuel injection valve side; a safety valve disposed between the water discharge passage and the water filling pipe along a piston shaft of the water piston portion, and having an internal passage communicating with the water filling pipe; and a drain passage leading from the safety valve to the outside of the water injection pump, the safety valve causing the internal passage to be in a closed state closed with respect to the drain passage, thereby guiding the water pressurized by the water piston portion from the water discharge passage to the water injection pipe through the internal passage, the safety valve causing the internal passage to be in an open state open with respect to the drain passage by the pressure of the reverse flow liquid flowing back from the fuel injection valve to the internal passage through the water injection pipe, thereby guiding the reverse flow liquid to be discharged from the internal passage to the outside of the water injection pump through the drain passage.

In the above invention, a water injection pump according to the present invention includes: and a discharge check valve disposed between the safety valve and the water discharge passage along a piston shaft of the water piston portion, and restricting a flow direction of water discharged from the water discharge passage to a direction from the water discharge passage side toward the safety valve side.

In the above invention, a water injection pump according to the present invention includes: and a water supply check valve disposed between the safety valve and the water discharge passage along a piston shaft of the water piston portion, and configured to be switched between an open state in which a flow of water supplied into the water discharge passage through a water supply pipe is permitted and a closed state in which a reverse flow of water from the water discharge passage side to the water supply pipe side is prevented and a flow of water discharged from the water discharge passage to the safety valve side is permitted.

In the above-described invention, the water injection pump according to the present invention includes a plurality of the water discharge passages, a plurality of the water piston portions, and a plurality of the relief valves, respectively, the plurality of the water discharge passages are configured to communicate with the plurality of the fuel injection valves provided in one of the cylinders through a plurality of the water injection pipes, respectively, the plurality of the water piston portions are provided in the plurality of the water discharge passages so as to be capable of reciprocating, respectively, and the plurality of the relief valves are disposed on the plurality of the water injection pipes side of the plurality of the water discharge passages along each piston axis of the plurality of the water piston portions, respectively.

In the above invention, the liquid discharge passage of the water injection pump according to the present invention is constituted by: a plurality of branch passages communicating with the plurality of relief valves, respectively; and a merging passage that merges with the plurality of branch passages and communicates with the outside of the water injection pump.

In the above invention, a water injection pump according to the present invention includes: a water tank having the water discharge passage and the water piston portion inside thereof; and a safety valve block having the safety valve and the drain passage inside, the safety valve block being detachably attached to an upper portion of the water tank by a fastening member.

In the above invention, a water injection pump according to the present invention includes: a discharge check valve block disposed between the safety valve block and the water tank, the discharge check valve block having the discharge check valve therein; and a water supply check valve block disposed between the discharge check valve block and the water tank, the water supply check valve block having the water supply check valve therein, the water supply check valve block, the discharge check valve block, and the safety valve block being detachably mounted on an upper portion of the water tank by the fastening member.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the water injection pump of the present invention, the following effects are achieved: it is possible to avoid excessive pressurization due to a reverse flow liquid such as fuel that flows in a reverse direction from a fuel injection valve, and to achieve a reduction in the size of the device.

Drawings

Fig. 1 is a schematic diagram showing a configuration example of a fuel injection system of a marine diesel engine according to an embodiment of the present invention.

Fig. 2 is a schematic side sectional view showing a configuration example of a water injection pump according to an embodiment of the present invention.

Fig. 3 is a schematic sectional view taken along line a-a of the water injection pump shown in fig. 2.

Fig. 4 is a schematic sectional view of the water injection pump shown in fig. 2 taken along line B-B.

Fig. 5 is a schematic cross-sectional view of the water injection pump shown in fig. 2 taken along line C-C.

Fig. 6 is a schematic sectional view of the water injection pump shown in fig. 2 taken along line D-D.

Fig. 7 is a schematic side sectional view showing one configuration example of a water supply check valve, a discharge check valve, and a safety valve of the water injection pump according to the embodiment of the present invention.

Fig. 8 is a diagram for explaining the operation of the safety valve of the water injection pump according to the embodiment of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the water injection pump according to the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the present embodiment. Note that the drawings are schematic, and the dimensional relationship, the ratio, and the like of the elements may be different from those in reality. The drawings may include portions having different dimensional relationships and ratios from each other. In the drawings, the same components are denoted by the same reference numerals.

(Structure of Fuel injection System)

First, the configuration of a fuel injection system of a marine diesel engine to which a water injection pump according to an embodiment of the present invention is applied will be described, and fig. 1 is a schematic diagram showing a configuration example of the fuel injection system of the marine diesel engine according to the embodiment of the present invention. As shown in fig. 1, the fuel injection system 100 includes a plurality of (three in the present embodiment) fuel injection valves 20A, 20B, and 20C, a fuel pressure feed system 30, a downstream side water injection system 40, and an upstream side water injection system 50. The fuel injection system 100 includes a water supply pump 61, a water supply pipe 62, an accumulator 71, a high-pressure pump 72, a detector 81, and a controller 82. In fig. 1, solid arrows indicate the flow of fluid such as fuel and water, and broken arrows indicate electrical signal lines.

The fuel injection valves 20A, 20B, and 20C are examples of a plurality of fuel injection valves for injecting fuel and water into a combustion chamber (none of which is shown) in a cylinder of a marine diesel engine. Although not shown in fig. 1, the fuel injection valves 20A, 20B, and 20C are provided in one cylinder. For example, the fuel injection valves 20A, 20B, and 20C are arranged at predetermined intervals along the circumferential direction of the cylinder.

As shown in fig. 1, the fuel injection valve 20A has an injection port 21, a fuel passage 22 communicating with the injection port 21, an internal passage 23 communicating with the fuel passage 22, and check valves 24a, 24 b. One end of the fuel passage 22 is connected to the injection port 21 and the other end is connected to the fuel injection pipe 32 (for example, a branch pipe 32a thereof). Further, a pipe of the upstream side water injection system 50 (for example, the upstream side water injection pipe 52a) is connected to the upstream side water injection position (the second water injection position P2) of the fuel passage 22 via the check valve 24 a. One end of the internal passage 23 is connected to a water injection position (first water injection position P1) on the downstream side of the fuel passage 22, and the other end is connected to a pipe (for example, the downstream water injection pipe 42a) of the downstream side water injection system 40. The check valve 24a enables the water to flow from the upstream side water injection system 50 to the fuel passage 22 of the fuel injection valve 20A, and prevents the water from flowing backward. The check valve 24b is provided in the middle of the internal passage 23. The check valve 24b enables the water from the downstream water injection system 40 to flow through the internal passage 23 toward the fuel passage 22, and prevents the reverse flow thereof.

The fuel injection valve 20A having the above-described configuration injects fuel pressure-fed by the fuel pressure-feeding system 30, water injected by the downstream-side water injection system 40, and water injected by the upstream-side water injection system 50 in layers from the injection port 21 into the combustion chamber in the cylinder. The fuel injection valves 20B and 20C have the same structure as the fuel injection valve 20A described above.

The fuel pressure-feed system 30 is a device for pressure-feeding fuel to the fuel injection valves 20A, 20B, and 20C. As shown in fig. 1, the fuel pressure feed system 30 includes a fuel injection pump 31, a fuel injection pipe 32, and a control valve 35.

The fuel injection pump 31 is a hydraulically driven pump driven by the pressure of the hydraulic oil, and pumps fuel to the fuel injection valves 20A, 20B, and 20C through the fuel injection pipe 32. The pressure-feeding action of the fuel injection valve 31 is to perform the laminar injection of the fuel and water from the injection port 21 to the combustion chamber in the cylinder with respect to the fuel injection valves 20A, 20B, and 20C.

One end of the fuel injection pipe 32 is connected to a discharge port of the fuel injection pump 31. A branch portion 33 is provided in the middle of the fuel injection pipe 32. The fuel injection pipe 32 branches from the branch portion 33 toward the other end into a plurality of branch pipes (three branch pipes 32a, 32b, and 32c in embodiment 1). As shown in fig. 1, a branch pipe 32a of branch pipes 32a, 32b, and 32c of the fuel injection pipe 32 is connected to the fuel passage 22 of the fuel injection valve 20A, and the fuel injection pipe 32 communicates the fuel injection valve 20A with the fuel injection pump 31 via the branch pipe 32 a. Similarly, the remaining branch pipes 32B and 32C are connected to the fuel passages 22 of the fuel injection valves 20B and 20C, respectively.

The control valve 35 controls the supply of the working oil from the pressure accumulation portion 71 to the fuel injection pump 31. The control valve 35 is opened during the injection period in which the fuel and water are injected from the fuel injection valves 20A, 20B, and 20C into the combustion chamber, and supplies the working oil in the pressure accumulating portion 71 to the fuel injection pump 31. On the other hand, the control valve 35 is closed during the injection suspension period of the fuel injection valves 20A, 20B, and 20C, and stops the supply of the hydraulic oil from the pressure accumulator 71 to the fuel injection pump 31. The timing of the opening and closing drive of the control valve 35 is controlled by the control unit 82.

The downstream side water injection system 40 is a device for injecting water to a water injection position on the downstream side of each fuel passage 22 of the fuel injection valves 20A, 20B, and 20C. As shown in fig. 1, the downstream side water injection system 40 includes a first water injection pump 41, downstream side water injection pipes 42a, 42b, and 42c, and a control valve 45.

The first water injection pump 41 is an example of the water injection pump of the present embodiment. The downstream water injection pipes 42a, 42b, and 42c are examples of water injection pipes that communicate the water injection pump and the fuel injection valve. As shown in fig. 1, one end of the downstream water injection pipe 42a is connected to the first discharge port of the first water injection pump 41, and the other end is connected to the internal passage 23 of the fuel injection valve 20A. The first water injection pump 41 injects water to the water injection position (i.e., the first water injection position P1) on the downstream side of the fuel passage 22 by pressure-feeding water to the fuel passage 22 of the fuel injection valve 20A through the downstream water injection pipe 42a and the like. One end of the downstream water injection pipe 42B is connected to the second discharge port of the first water injection pump 41, and the other end is connected to the internal passage of the fuel injection valve 20B. As in the case of the fuel injection valve 20A, the first water injection pump 41 injects water into the first water injection position P1 of the fuel passage 22 of the fuel injection valve 20B through the downstream side water injection pipe 42B and the like. One end of the downstream water injection pipe 42C is connected to the third discharge port of the first water injection pump 41, and the other end is connected to the internal passage of the fuel injection valve 20C. As in the case of the fuel injection valve 20A, the first water injection pump 41 injects water into the first water injection position P1 of the fuel passage 22 of the fuel injection valve 20C through the downstream side water injection pipe 42C and the like.

The control valve 45 controls the supply of the hydraulic oil from the pressure accumulator 71 to the first water injection pump 41. The control valve 45 is opened during a period (i.e., an injection suspension period) other than the period during which the fuel and the water are injected by the fuel injection valves 20A, 20B, and 20C, and supplies the hydraulic oil in the pressure storage portion 71 to the first water injection pump 41. On the other hand, the control valve 45 is closed during the injection of the fuel and the water, and stops the supply of the hydraulic oil from the pressure accumulator 71 to the first water injection pump 41. The timing of the opening and closing drive of the control valve 45 is controlled by the control unit 82.

The upstream side water injection system 50 is a device for injecting water to a water injection position on the upstream side of each fuel passage 22 of the fuel injection valves 20A, 20B, and 20C. As shown in fig. 1, the upstream side water injection system 50 includes a second water injection pump 51, upstream side water injection pipes 52a, 52b, and 52c, and a control valve 55.

The second water injection pump 51 is an example of the water injection pump according to the present embodiment. The upstream side water injection pipes 52a, 52b, and 52c are examples of water injection pipes that communicate the water injection pump and the fuel injection valve. As shown in fig. 1, one end of the upstream side water injection pipe 52a is connected to the first discharge port of the second water injection pump 51, and the other end is connected to the fuel passage 22 of the fuel injection valve 20A via the check valve 24 a. The second water injection pump 51 injects water into the upstream water injection position (i.e., the second water injection position P2) of the fuel passage 22 by pressure-feeding water to the fuel passage 22 of the fuel injection valve 20A through the upstream water injection pipe 52a and the like. One end of the upstream water injection pipe 52B is connected to the second discharge port of the second water injection pump 51, and the other end is connected to the fuel passage 22 of the fuel injection valve 20B via a check valve (not shown). As in the case of the fuel injection valve 20A, the second water injection pump 51 injects water into the second water injection position P2 of the fuel passage 22 of the fuel injection valve 20B through the upstream side water injection pipe 52B and the like. One end of the upstream water injection pipe 52C is connected to the third discharge port of the second water injection pump 51, and the other end is connected to the fuel passage 22 of the fuel injection valve 20C via a check valve (not shown). As in the case of the fuel injection valve 20A, the second water injection pump 51 injects water into the second water injection position P2 of the fuel passage 22 of the fuel injection valve 20C through the upstream side water injection pipe 52C and the like.

The control valve 55 controls the supply of the hydraulic oil from the pressure accumulator 71 to the second water injection pump 51. The control valve 55 is opened during the injection suspension period of the fuel injection valves 20A, 20B, and 20C, and supplies the hydraulic oil in the pressure storage portion 71 to the second water injection pump 51. On the other hand, the control valve 55 is closed during the injection period of the fuel and water by the fuel injection valves 20A, 20B, and 20C, and stops the supply of the hydraulic oil from the pressure accumulator 71 to the second water injection pump 51. The timing of the opening and closing operation of the control valve 55 is controlled by the control unit 82.

The water supply pump 61 is a pump for supplying water to be discharged to the first and second water injection pumps 41 and 51. One end of the water supply pipe 62 is connected to the water supply pump 61 and the other end is branched into branch pipes 62a and 62 b. One branch pipe 62a of the water supply pipe 62 is connected to the first water filling pump 41. The other branch pipe 62b of the water supply pipe 62 is connected to the second water filling pump 51. The water supply pump 61 supplies the water to be discharged to the first water injection pump 41 through a branch pipe 62a of the water supply pipe 62, and supplies the water to be discharged to the second water injection pump 51 through a branch pipe 62b of the water supply pipe 62.

The pressure accumulation unit 71 accumulates the pressure of the hydraulic oil that operates the fuel pressure feed system 30, the downstream side water injection system 40, and the upstream side water injection system 50. As shown in fig. 1, the accumulator 71 accumulates the pressure of the hydraulic oil in an internal accumulator chamber by accumulating the hydraulic oil discharged (pressure-fed) from the high-pressure pump 72 through a pipe or the like. In this way, the pressure of the hydraulic oil accumulated in the pressure accumulation portion 71 is adjusted by the discharge amount of the hydraulic oil discharged from the high-pressure pump 72 to the pressure accumulation portion 71. The pressure of the hydraulic oil accumulated in the pressure accumulator 71 is commonly used for the operation of the fuel injection pump 31, the operation of the first water injection pump 41, and the operation of the second water injection pump 51.

The detection unit 81 detects a crank angle of a marine diesel engine (not shown). The detection unit 81 detects the crank angle with the lapse of time, and sends an electric signal indicating the detected crank angle to the control unit 82 each time.

The control unit 82 receives an electric signal from the detection unit 81, and controls the open/close driving of the control valve 35 of the fuel pressure-feed system 30 so that the control valve 35 is opened at a timing when the crank angle indicated by the received electric signal becomes a predetermined rotation angle. The control unit 82 controls the operation timing of the fuel injection pump 31, that is, the injection timing of the fuel and water from the fuel injection valves 20A, 20B, and 20C into the combustion chamber by controlling the opening/closing drive of the control valve 35. At this injection timing, the fuel pressure-fed from the fuel injection pump 31, the water discharged from the first water injection pump 41, and the water discharged from the second water injection pump 51 are injected in layers from the fuel injection valves 20A, 20B, and 20C into the combustion chamber by the pressure-fed action of the fuel injection pump 31. Subsequently, the fuel passages 22 and the fuel injection pipes 32 of the fuel injection valves 20A, 20B, and 20C are filled with the remaining fuel that is not injected.

In the injection suspension period of the fuel injection valves 20A, 20B, and 20C, the controller 82 controls the operation timings of the first and second water injection pumps 41 and 51 so that water is injected into the water injection position (first water injection position P1) on the downstream side and the water injection position (second water injection position P2) on the upstream side of each of the fuel passages 22 in a state filled with fuel. During the injection suspension period, the water discharged from the first water injection pump 41 and the water discharged from the second water injection pump 51 are injected into the first water injection position P1 and the second water injection position P2 of the fuel passages 22 of the fuel injection valves 20A, 20B, and 20C, respectively, at a pressure higher than the pressure (residual fuel pressure) of the fuel remaining in the fuel passages 22.

(Structure of Water injection pump)

Next, the structure of the water injection pump according to the embodiment of the present invention will be described. Fig. 2 is a schematic side sectional view showing a configuration example of a water injection pump according to an embodiment of the present invention. Fig. 3 is a schematic sectional view taken along line a-a of the water injection pump shown in fig. 2. Fig. 4 is a schematic sectional view of the water injection pump shown in fig. 2 taken along line B-B. Fig. 5 is a schematic cross-sectional view of the water injection pump shown in fig. 2 taken along line C-C. Fig. 6 is a schematic sectional view of the water injection pump shown in fig. 2 taken along line D-D. Hereinafter, the first water injection pump 41 (see fig. 1) for injecting water into the first water injection position P1 of the fuel passages 22 of the fuel injection valves 20A, 20B, and 20C is exemplified as an example of the water injection pump according to the present embodiment. The second water injection pump 51 is similar in structure to the first water injection pump 41, except that the water injection position of each fuel passage 22 for the fuel injection valves 20A, 20B, and 20C is different from the first water injection pump 41 (i.e., the second water injection position P2).

The first water injection pump 41 is a hydraulically driven water injection pump that discharges water by the pressure of the hydraulic oil. As shown in fig. 2 to 6, the first water injection pump 41 includes a water cylinder 1, a hydraulic cylinder 5, a plurality of (three in the present embodiment) water piston portions 6a, 6b, and 6c, a hydraulic piston portion 7, a coupling portion 8, and an urging portion 9. The first fill pump 41 includes a water supply check valve block 10, a plurality of (three in the present embodiment) water supply check valves 11a, 11b, and 11c, a discharge check valve block 12, a plurality of (three in the present embodiment) discharge check valves 13a, 13b, and 13c, a relief valve block 14, a plurality of (three in the present embodiment) relief valves 15a, 15b, and 15c, and a drain passage 14 e.

The water tank 1 is, for example, a hollow cylindrical member, and has water discharge passages 2a, 2b, and 2c and water piston portions 6a, 6b, and 6c for discharging water therein, as shown in fig. 2 and 3. In addition, the water tub 1 has an internal space 4, and the internal space 4 is continuous with the water discharge passages 2a, 2b, 2 c.

The water discharge passages 2a, 2b, and 2c are examples of a plurality of water discharge passages configured to communicate with a water injection pipe connected to a fuel injection valve of a cylinder. For example, the water discharge passages 2a, 2b, and 2c are configured to communicate with a plurality of downstream water injection pipes 42a, 42b, and 42c shown in fig. 1. That is, in the present embodiment, the water discharge passages 2a, 2B, and 2C are configured to communicate with the plurality of fuel injection valves 20A, 20B, and 20C provided in one cylinder, respectively, via the plurality of downstream side water pipes 42a, 42B, and 42C.

Specifically, as shown in fig. 2 and 3, the water piston portion 6a of the water discharge passage 2a is formed in a shape (for example, a cylindrical shape) slidable in a reciprocating direction. The water discharge passage 2a temporarily stores water to be discharged, which is supplied through a passage (not shown) formed inside the water supply check valve block 10 and the water supply check valve 11 a. The water discharge passage 2a communicates with the discharge port 16a of the cap 16 via the internal passage 111a (see fig. 4) of the water supply check valve 11a, the openable and closable internal passage 131a (see fig. 5) of the discharge check valve 13a, and the internal passage 151a (see fig. 6) of the safety valve 15 a. The water discharge passage 2a communicates with the downstream water injection pipe 42a through the discharge port 16 a.

The water discharge passages 2b and 2c are each configured in the same manner as the water discharge passage 2a described above. That is, the water discharge passage 2b is formed in a shape in which the water piston portion 6b can slide in the reciprocating direction, and temporarily stores water to be discharged supplied through the water supply check valve 11b or the like. The water discharge passage 2b communicates with the discharge port 16b of the lid portion 16 via the internal passage 111b (see fig. 4) of the water supply check valve 11b, the openable and closable internal passage 131b (see fig. 5) of the discharge check valve 13b, and the internal passage 151b (see fig. 6) of the safety valve 15 b. The water discharge passage 2b communicates with the downstream water injection pipe 42b through the discharge port 16 b. The water discharge passage 2c is formed in a shape slidable in the reciprocating direction, and temporarily stores water to be discharged, which is supplied through the water supply check valve 11c and the like. The water discharge passage 2c communicates with the discharge port 16c of the cap 16 via the internal passage 111c (see fig. 4) of the water supply check valve 11c, the openable and closable internal passage 131c (see fig. 5) of the discharge check valve 13c, and the internal passage 151c (see fig. 6) of the safety valve 15 c. The water discharge passage 2c communicates with the downstream water injection pipe 42c through the discharge port 16 c.

These water discharge passages 2a, 2B, 2C communicate with the fuel injection valves 20A, 20B, 20C at the same fuel passage positions. For example, the water discharge passage 2a communicates with the first water filling position P1 of the fuel passage 22 of the fuel injection valve 20A through the downstream side water filling pipe 42 a. The water discharge passage 2B communicates with the first water filling position P1 of the fuel passage 22 of the fuel injection valve 20B through the downstream side water filling pipe 42B. The water discharge passage 2C communicates with the first water filling position P1 of the fuel passage 22 of the fuel injection valve 20C through the downstream side water filling pipe 42C.

The internal space 4 is a space for enabling the reciprocating movement of a plurality of (three in the present embodiment) water piston portions 6a, 6b, 6c in accordance with the operation of one hydraulic piston portion 7. As shown in fig. 2, the lower portions of the water piston portions 6a, 6b, and 6c, the upper portion of the hydraulic piston portion 7, and the connecting portion 8 connecting these portions are housed in the internal space 4 so as to be able to reciprocate.

The hydraulic cylinder 5 is a hollow cylindrical member capable of accommodating the hydraulic piston portion 7 so as to be capable of reciprocating. Specifically, as shown in fig. 2, the hydraulic cylinder 5 has a hydraulic oil chamber 5a for receiving hydraulic oil for operating the hydraulic piston portion 7. The hydraulic oil chamber 5a is formed to be able to house the hydraulic piston portion 7 so as to be able to reciprocate. The hydraulic cylinder 5 is coupled to the water cylinder 1 by a mounting bolt (not shown). The lower end of the hydraulic cylinder 5 is attached to hydraulic oil supply equipment such as the accumulator 71 and the control valve 45 shown in fig. 1.

The water piston portions 6a, 6b, and 6c are examples of water piston portions that pressurize water in the water discharge passage and discharge the water to the fuel injection valve side. In the present embodiment, the water piston portions 6a, 6b, and 6c are, for example, pistons having the same diameter, and are provided so as to be capable of reciprocating in the water discharge passages 2a, 2b, and 2c, respectively, as shown in fig. 2 and 3. Further, "the diameters of the water piston portions 6a, 6b, 6c are the same as each other" means that the diameters of the water piston portions 6a, 6b, 6c are within the manufacturing tolerance.

The water piston portion 6a reciprocates in the piston axial direction while sliding in the water discharge passage 2 a. At this time, the water piston portion 6a moves in the direction of the compressed water discharge passage 2a, thereby pressurizing the water in the water discharge passage 2a and discharging the water to the fuel injection valve 20A side. The water piston portion 6b reciprocates in the piston axial direction while sliding in the water discharge passage 2 b. At this time, the water piston portion 6B moves in the direction of the compressed water discharge passage 2B, thereby pressurizing the water in the water discharge passage 2B and discharging the water to the fuel injection valve 20B side. The water piston portion 6c reciprocates in the piston axial direction while sliding in the water discharge passage 2 c. At this time, the water piston portion 6C moves in the direction of the compressed water discharge passage 2C, thereby pressurizing the water in the water discharge passage 2C and discharging the water to the fuel injection valve 20C side.

The piston axial direction of the water piston portion 6a is the longitudinal direction of the piston shaft CL1 of the water piston portion 6 a. The piston axial direction of the water piston portion 6b is the longitudinal direction of the piston shaft CL2 of the water piston portion 6 b. The piston axial direction of the water piston portion 6c is the longitudinal direction of the piston shaft CL3 of the water piston portion 6 c. Hereinafter, unless otherwise specified, the piston axial direction refers to the piston axial direction of any or all of the water piston portions 6a, 6b, 6 c.

The hydraulic piston portion 7 is a piston that operates by the pressure of the hydraulic oil. As shown in fig. 2, the hydraulic piston portion 7 is housed in a hydraulic chamber 5a of the hydraulic cylinder 5 so as to be capable of reciprocating in the piston axial direction. The hydraulic piston portion 7 moves the water piston portions 6a, 6b, and 6c toward the outlet sides of the water discharge passages 2a, 2b, and 2c (toward the water supply check valves 11a, 11b, and 11c in the present embodiment), respectively, by the pressure of the hydraulic oil supplied to the hydraulic oil chamber 5 a. The hydraulic piston portion 7 pushes out the hydraulic oil from the hydraulic oil chamber 5a, moves (descends) in the piston axial direction, and returns to the original position before the operation.

The connection portion 8 is an example of a connection portion that connects a plurality of hydraulic piston portions and one hydraulic piston portion. Specifically, as shown in fig. 2, the lower end portions of the water piston portions 6a, 6b, and 6c are fixed to one end surface of the coupling portion 8, and the upper end portion of the hydraulic piston portion 7 is fixed to the other end surface thereof, whereby the water piston portions 6a, 6b, and 6c and the hydraulic piston portion 7 are coupled and integrated. The coupling portion 8 is housed in the internal space 4 of the water tub 1 so as to be capable of reciprocating. The water piston portions 6a, 6b, and 6c fixed to the connection portion 8 are in a state of being movable integrally with the hydraulic piston portion 7.

The biasing portion 9 biases the hydraulic piston portion 7 in a predetermined direction. The biasing portion 9 is formed of, for example, a compression spring, an air spring, or the like, and is provided above the hydraulic cylinder 5 as shown in fig. 2. A projection (not shown) of the hydraulic piston portion 7 is disposed on the biasing portion 9. The biasing portion 9 biases the hydraulic piston portion 7 in a direction (downward in the paper of fig. 2) in which the hydraulic oil is pushed out from the hydraulic oil chamber 5a by applying a biasing force to the protrusion.

As shown in fig. 2 and 4, the water supply check valve block 10 is a structure (for example, a structure having a cylindrical outer shape) having water supply check valves 11a, 11b, and 11c therein. The supply water check valve block 10 is disposed between the discharge check valve block 12 and the water tub 1. Although not shown in fig. 2 and 4, a water supply passage for communicating a water supply pipe 62 (specifically, a branch pipe 62a) communicating with the water supply pump 61 shown in fig. 1 with the water supply check valves 11a, 11b, and 11c is formed inside the water supply check valve block 10.

The water supply check valves 11a, 11b, and 11c are examples of check valves that restrict the flow direction of water supplied from the water supply pump 61 into the water discharge passages 2a, 2b, and 2 c. As shown in fig. 2, the water supply check valve 11a is disposed along the piston shaft CL1 of the water piston portion 6a in the water supply check valve block 10, specifically, between the discharge check valve 13a and the water discharge passage 2 a. The water supply check valve 11a enables the water flowing from the water supply pump 61 through the water supply pipe 62 and the water supply passage in the water supply check valve block 10 into the water discharge passage 2a to flow therethrough, and prevents the reverse flow thereof. In addition, as shown in fig. 4, the water supply check valve 11a has an internal passage 111 a. The water supply check valve 11a communicates the water discharge passage 2a with the discharge check valve 13a via the internal passage 111 a.

The water supply check valve 11b is disposed along the piston shaft CL2 of the water piston portion 6b in the water supply check valve block 10, specifically, between the discharge check valve 13b (see fig. 5) and the water discharge passage 2b (see fig. 3). The water supply check valve 11b enables the water flowing from the water supply pump 61 through the water supply pipe 62 and the water supply passage in the water supply check valve block 10 into the water discharge passage 2b to flow therethrough, and prevents the reverse flow thereof. In addition, as shown in fig. 4, the water supply check valve 11b has an internal passage 111 b. The water supply check valve 11b communicates the water discharge passage 2b with the discharge check valve 13b via the internal passage 111 b. The water supply check valve 11c is disposed along the piston shaft CL3 of the water piston portion 6c in the water supply check valve block 10, specifically, between the discharge check valve 13c (see fig. 5) and the water discharge passage 2c (see fig. 3). The water supply check valve 11c enables the water flowing from the water supply pump 61 through the water supply pipe 62 and the water supply passage in the water supply check valve block 10 to flow into the water discharge passage 2c, and prevents the reverse flow thereof. In addition, as shown in fig. 4, the water supply check valve 11c has an internal passage 111 c. The water supply check valve 11c communicates the water discharge passage 2c with the discharge check valve 13c via the internal passage 111 c.

As shown in fig. 2 and 5, the discharge check valve block 12 is a structure (for example, a structure having a cylindrical outer shape) having discharge check valves 13a, 13b, and 13c therein. The discharge check valve block 12 is disposed between the relief valve block 14 and the cylinder 1.

The discharge check valves 13a, 13b, and 13c are examples of check valves that restrict the flow direction of water discharged from the water discharge passages 2a, 2b, and 2 c. As shown in fig. 2, the discharge check valve 13a is disposed along the piston shaft CL1 of the water piston portion 6a in the discharge check valve block 12, specifically, between the safety valve 15a and the water discharge passage 2a (between the safety valve 15a and the water supply check valve 11a in the present embodiment). The discharge check valve 13a enables the water flowing from the water discharge passage 2a toward the fuel injection valve 20A to flow therethrough, and prevents the water from flowing backward. As shown in fig. 5, the discharge check valve 13a has an internal passage 131 a. The discharge check valve 13a communicates the water supply check valve 11a communicating with the water discharge passage 2a and the relief valve 15a communicating with the fuel injection valve 20A via the internal passage 131 a.

The discharge check valve 13b is disposed along the piston shaft CL2 of the water piston portion 6b in the discharge check valve block 12, specifically, between the safety valve 15b (see fig. 6) and the water discharge passage 2b (in the present embodiment, between the safety valve 15b and the water supply check valve 11b (see fig. 4)). The discharge check valve 13B enables the water flowing from the water discharge passage 2B toward the fuel injection valve 20B to flow therethrough, and prevents the water from flowing backward. As shown in fig. 5, the discharge check valve 13b has an internal passage 131 b. The discharge check valve 13B communicates the water supply check valve 11B communicating with the water discharge passage 2B and the relief valve 15B communicating with the fuel injection valve 20B via the internal passage 131B. The discharge check valve 13c is disposed along the piston shaft CL3 of the water piston portion 6c in the discharge check valve block 12, specifically, between the safety valve 15c (see fig. 6) and the water discharge passage 2c (in the present embodiment, between the safety valve 15c and the water supply check valve 11c (see fig. 4)). The discharge check valve 13C enables the water flowing from the water discharge passage 2C toward the fuel injection valve 20C to flow therethrough, and prevents the water from flowing backward. As shown in fig. 5, the discharge check valve 13c has an internal passage 131 c. The discharge check valve 13C communicates the water supply check valve 11C communicating with the water discharge passage 2C and the relief valve 15C communicating with the fuel injection valve 20C via the internal passage 131C.

As shown in fig. 2 and 6, the relief valve block 14 is a structure (for example, a structure having a cylindrical outer shape) having relief valves 15a, 15b, and 15c and a drain passage 14e therein. The relief valve block 14 is disposed between the discharge check valve block 12 and the cap 16, and is detachably mounted to the upper portion of the cylinder 1 by a mounting bolt 17 as an example of a fastening member.

The relief valves 15a, 15b, and 15c are examples of relief valves that protect the water injection pump from the high-pressure reverse flow liquid that flows back from the fuel injection valve. The relief valves 15a, 15b, and 15c are disposed along the piston shafts CL1, CL2, and CL3 of the water piston portions 6a, 6b, and 6c on the downstream water injection pipes 42a, 42b, and 42c side of the water discharge passages 2a, 2b, and 2c, respectively.

As shown in fig. 2, the relief valve 15a is disposed along the piston shaft CL1 of the water piston portion 6a in the relief valve block 14, specifically, between the water discharge passage 2a and the downstream water injection pipe 42a shown in fig. 1 (between the discharge port 16a communicating with the downstream water injection pipe 42a and the discharge check valve 13a in the present embodiment). As shown in fig. 6, the relief valve 15a has an internal passage 151 a. The internal passage 151a of the relief valve 15a communicates with the downstream water injection pipe 42a via the discharge port 16a, and communicates with the fuel injection valve 20A via the downstream water injection pipe 42 a. The safety valve 15a guides water discharged from the water discharge passage 2a to the downstream water injection pipe 42a through the internal passage 151 a. The relief valve 15a guides the reverse flow liquid flowing back from the fuel injection valve 20A to be discharged from the internal passage 151a to the outside of the first water injection pump 41 through the drain passage 14 e.

The relief valve 15b is disposed along the piston shaft CL2 of the water piston portion 6b in the relief valve block 14, specifically, between the water discharge passage 2b and the downstream water injection pipe 42b shown in fig. 1 (between the discharge port 16b communicating with the downstream water injection pipe 42b and the discharge check valve 13b in the present embodiment). As shown in fig. 6, the relief valve 15b has an internal passage 151 b. The internal passage 151B of the relief valve 15B communicates with the downstream water injection pipe 42B via the discharge port 16B, and communicates with the fuel injection valve 20B via the downstream water injection pipe 42B. The safety valve 15b guides water discharged from the water discharge passage 2b to the downstream water injection pipe 42b through the internal passage 151 b. The relief valve 15B guides the reverse flow liquid flowing back from the fuel injection valve 20B to flow from the internal passage 151B through the drain passage 14e and to be discharged to the outside of the first water injection pump 41.

The relief valve 15c is disposed along the piston shaft CL1 of the water piston portion 6c in the relief valve block 14, specifically, between the water discharge passage 2c and the downstream water injection pipe 42c shown in fig. 1 (between the discharge port 16c communicating with the downstream water injection pipe 42c and the discharge check valve 13c in the present embodiment). As shown in fig. 6, the relief valve 15c has an internal passage 151 c. The internal passage 151C of the relief valve 15C communicates with the downstream water injection pipe 42C via the discharge port 16C, and communicates with the fuel injection valve 20C via the downstream water injection pipe 42C. The safety valve 15c guides the water discharged from the water discharge passage 2c to the downstream water injection pipe 42c through the internal passage 151 c. The relief valve 15C guides the reverse flow liquid flowing back from the fuel injection valve 20C to flow from the internal passage 151C through the drain passage 14e and to be discharged to the outside of the first water injection pump 41.

The drain passage 14e is an example of a passage for discharging the reverse flow liquid, which flows back from the fuel injection valve to the water injection pump, to the outside of the water injection pump. As shown in fig. 6, the drain passage 14e is formed in the safety valve block 14 so as to lead from the safety valves 15a, 15b, and 15c to the outside of the first water injection pump 41. In the present embodiment, for example, the drain passage 14e is constituted by a plurality of (three in fig. 6) branch passages 14a, 14b, and 14c that communicate with the safety valves 15a, 15b, and 15c, respectively, and a merging passage 14d that merges with these branch passages 14a, 14b, and 14c and communicates with the outside of the first water injection pump 41.

The branch passage 14a is formed in the relief valve block 14 such that one end portion communicates with the merging passage 14d and the other end portion is formed in a ring shape surrounding the relief valve 15 a. The annular portion of the branch passage 14a communicates with the internal passage 151a of the relief valve 15a so as to be openable and closable in accordance with the opening and closing operation of the relief valve 15 a. The branch passage 14a leads the backflow liquid flowing out of the internal passage 151a of the safety valve 15a to the merging passage 14 d. The branch passage 14b is formed in the relief valve block 14 such that one end portion communicates with the merging passage 14d and the other end portion is formed in a ring shape surrounding the relief valve 15 b. The annular portion of the branch passage 14b is in openable and closable communication with the internal passage 151b of the relief valve 15b in accordance with the opening and closing operation of the relief valve 15 b. The branch passage 14b guides the backflow liquid flowing out of the internal passage 151b of the safety valve 15b to the merging passage 14 d. The branch passage 14c is formed in the relief valve block 14 such that one end portion communicates with the merging passage 14d and the other end portion is formed in a ring shape surrounding the relief valve 15 c. The annular portion of the branch passage 14c is in openable and closable communication with the internal passage 151c of the relief valve 15c in accordance with the opening and closing operation of the relief valve 15 c. The branch passage 14c guides the backflow liquid flowing out of the internal passage 151c of the safety valve 15c to the merging passage 14 d.

The merging passage 14d is formed in the relief valve block 14 so as to merge with the branch passages 14a, 14b, and 14c and communicate with the drain port 14 f. As shown in fig. 6, the drain port 14f is formed in the relief valve block 14 such that one end portion communicates with the merging passage 14d and the other end portion opens to the outside of the first water injection pump 41. The merging passage 14d guides the backflow liquid flowing from at least one of the branch passages 14a, 14b, and 14c to the drain port 14f side, and discharges the backflow liquid from the drain port 14f to the outside of the first water injection pump 41. Although not shown, a discharge pipe for guiding the discharged counter flow liquid into a device such as a tank is connected to the discharge port 14 f.

The reverse flow liquid may be, for example, fuel that flows from the fuel injection valve through the water injection pipe and then to the water injection pump, or water that flows back through the water injection pipe and is pushed back to the water injection pump by the pressure of the fuel. In the case where the water injection pump is the first water injection pump 41, the fuel injection valves 20A, 20B, and 20C are exemplified as the fuel injection valves, and the downstream water injection pipes 42a, 42B, and 42C are exemplified as the water injection pipes. In the case where the water injection pump is the second water injection pump 51, the fuel injection valves 20A, 20B, and 20C are exemplified as the fuel injection valves, and the upstream water injection pipes 52a, 52B, and 52C are exemplified as the water injection pipes.

As shown in fig. 6, an oil passage for supplying lubricating oil to the relief valves 15a, 15b, and 15c is formed in the relief valve block 14, and a plug 18 for closing an outlet of the oil passage is attached to the relief valve block 14. Although not shown, an oil passage for supplying lubricating oil to the water supply check valves 11a, 11b, and 11c is formed in the water supply check valve block 10, and a plug for closing an outlet of the oil passage is attached to the water supply check valve block 10. An oil passage for supplying the discharge check valves 13a, 13b, and 13c with lubricating oil is formed in the discharge check valve block 12, and a plug for closing an outlet of the oil passage is attached to the discharge check valve block 12.

On the other hand, as shown in fig. 2, a lid portion 16 is provided at the upper end portion of the safety valve block 14. In the present embodiment, the lid portion 16 is detachably attached by the attachment bolts 17 (an example of a fastening member) so as to sandwich the water supply check valve block 10, the discharge check valve block 12, and the safety valve block 14 between the upper end portion of the cylinder 1 and the lid portion 16. Thus, the supply check valve block 10, the discharge check valve block 12, and the relief valve block 14 are detachably mounted to the upper portion of the water tub 1 by the mounting bolts 17. The lid portion 16 presses and fixes the rear end portions of the valve stems of the safety valves 15a, 15b, and 15c to the safety valve block 14.

As shown in fig. 2, the lid portion 16 is formed with discharge ports 16a, 16b, and 16c corresponding to the water discharge passages 2a, 2b, and 2 c. The discharge port 16a is a first discharge port communicating with the water discharge passage 2a via the internal passage 111a of the water supply check valve 11a, the internal passage 131a of the discharge check valve 13a, and the internal passage 151a of the relief valve 15 a. The discharge port 16b is a second discharge port communicating with the water discharge passage 2b via the internal passage 111b of the water supply check valve 11b, the internal passage 131b of the discharge check valve 13b, and the internal passage 151b of the relief valve 15 b. The discharge port 16c is a third discharge port that communicates with the water discharge passage 2c via the internal passage 111c of the water supply check valve 11c, the internal passage 131c of the discharge check valve 13c, and the internal passage 152c of the relief valve 15 c. The lid portion 16 is attached to the upper end portion of the safety valve block 14 such that the discharge port 16a communicates with the internal passage 151a of the safety valve 15a, the discharge port 16b communicates with the internal passage 151b of the safety valve 15b, and the discharge port 16c communicates with the internal passage 151c of the safety valve 15 c.

Here, as described above, the water supply check valve 11a, the discharge check valve 13a, and the relief valve 15a are disposed along the piston shaft CL1 of the water piston portion 6 a. That is, as shown in fig. 2, the water supply check valve 11a, the discharge check valve 13a, and the relief valve 15a are located on the piston shaft CL1 so as to be able to communicate with the water discharge passage 2 a. At this time, the central axes of the water supply check valve 11a, the discharge check valve 13a, and the relief valve 15a (for example, the central axes of the internal passages 111a, 131a, and 151 a) do not need to be completely coaxial with the piston shaft CL 1. Further, the water supply check valve 11a, the discharge check valve 13a, and the relief valve 15a are preferably disposed such that the piston shaft CL1 passes through the inside of the internal passages 111a, 131a, and 151a, and more preferably, the piston shaft CL1 and the central axes of the internal passages 111a, 131a, and 151a are disposed parallel to each other or coincide with each other (are the same axis). The arrangement of the water supply check valve 11a, the discharge check valve 13a, and the relief valve 15a with respect to the piston shaft CL1 is the same as the arrangement of the water supply check valve 11b, the discharge check valve 13b, and the relief valve 15b with respect to the piston shaft CL2 of the water piston portion 6b, and the arrangement of the water supply check valve 11c, the discharge check valve 13c, and the relief valve 15c with respect to the piston shaft CL3 of the water piston portion 6 c.

(Structure of Water supply check valve, discharge check valve, safety valve)

Next, the structures of the water supply check valve, the discharge check valve, and the safety valve of the water injection pump according to the embodiment of the present invention will be described. Fig. 7 is a schematic side sectional view showing one configuration example of a water supply check valve, a discharge check valve, and a safety valve of the water injection pump according to the embodiment of the present invention. Hereinafter, the water supply check valve 11a, the discharge check valve 13a, and the safety valve 15a of the first water injection pump 41 shown in fig. 2 are exemplified as the water supply check valve, the discharge check valve, and the safety valve of the water injection pump according to the present embodiment. The structures of the water supply check valves 11b and 11c, the discharge check valves 13b and 13c, and the safety valves 15b and 15c are the same as those of the water supply check valve 11a, the discharge check valve 13a, and the safety valve 15a, respectively, except that the water discharge passage and the discharge port communicating with each other are different from those described above.

As shown in fig. 7, the water supply check valve 11a includes a valve body 110a and a spring 113 a. The valve body 110a has an internal passage 111a and a pressure receiving portion 112a, and is housed in the water supply check valve block 10 so as to be capable of reciprocating in the valve shaft direction F. The internal passage 111a is a passage for passing water discharged from the water discharge passage 2a, and is formed in the valve body 110 a. For example, as shown in fig. 7, the internal passage 111a communicates with the water discharge passage 2a on the distal end side and with the communication passage 12a on the rear end side, and the communication passage 12a communicates with the discharge check valve 13a so as to be openable and closable. The communication passage 12a is formed in the discharge check valve block 12, for example, and between the water supply check valve 11a and the discharge check valve 13 a. The pressure receiving portion 112a is a portion that receives pressure for opening the valve element 110a, and is formed in an annular shape along the circumferential direction in an outer peripheral portion near a tip end portion (end portion on the water discharge passage 2a side) of the valve element 110 a. The spring 113a is housed on the rear end side in the valve body 110 a. For example, as shown in fig. 7, the spring 113a is contracted from a natural length between the projection in the valve body 110a and the discharge check valve block 12, and biases the valve body 110a toward the water discharge passage 2 a. The biasing force of the spring 113a is weaker than the pressure of the water supplied from the water supply pump 61 (see fig. 1).

The water supply check valve 11a having such a structure switches between the open state and the closed state by reciprocating the valve body 110a in the valve shaft direction F. The open state of the water supply check valve 11a is a state that allows the flow of water supplied from the water supply pump 61 into the water discharge passage 2a through the water supply pipe 62. The closed state of the water supply check valve 11a is a state in which the reverse flow of water from the water discharge passage 2a side to the supply water pipe 62 side is prevented and the flow of water discharged from the water discharge passage 2a to the discharge check valve 13a side is allowed.

Specifically, in the water supply check valve 11a, the valve body 110a is pressed at its tip end portion against the outlet end portion of the water discharge passage 2a by the biasing force of the spring 113 a. Thus, the valve body 110a brings the water discharge passage 2a into communication with the internal passage 111a, and blocks the communication between the water discharge passage 2a and a water supply passage (not shown) in the water supply check valve block 10, thereby bringing the valve body into the closed state described above. When the pressure of the water fed through the water supply pipe 62 into the water supply passage (not shown) of the water supply check valve block 10 is received by the pressure receiving portion 112a, the valve body 110a is moved in a direction against the biasing force of the spring 113a by the pressure. Accordingly, the valve body 110a is separated from the water discharge passage 2a, and the water discharge passage 2a and the water supply passage in the water supply check valve block 10 are communicated with each other, thereby being in the open state. Subsequently, when the supply of water into the water discharge passage 2a is completed, the valve body 110a approaches the water discharge passage 2a by the biasing force of the spring 113a, and the valve body is again in the closed state described above.

As shown in fig. 7, the discharge check valve 13a includes a valve body 130a and a spring 113 a. The valve body 130a has an internal passage 131a, a pressure receiving portion 132a, and a receiving port 134a, and is housed in the discharge check valve block 12 so as to be capable of reciprocating in the valve shaft direction F. The internal passage 131a is a passage for passing water discharged from the water discharge passage 2a, and is formed in the valve body 130 a. The receiving port 134a is formed in the distal end portion of the valve body 130a so as to communicate with the distal end side of the internal passage 131 a. For example, the receiving ports 134a are formed to extend in four directions from the central axis of the valve core 130 a. For example, as shown in fig. 7, the internal passage 131a communicates with a communication passage 12a on the distal end side, the communication passage 12a communicates with the water supply check valve 11a via a receiving port 134a so as to be openable and closable, and the internal passage 131a communicates with a communication passage 14h communicating with the relief valve 15a on the rear end side. The communication passage 14h is formed between the discharge check valve 13a and the relief valve 15a in the relief valve block 14, for example. The pressure receiving portion 132a is a portion that receives pressure for opening the valve body 130a, and is formed at the tip end portion (end portion on the water supply check valve 11a side) of the valve body 130 a. The spring 133 is housed in the spool 130 a. For example, as shown in fig. 7, the spring 133a is in a state of contracting from a natural length between the tip end side portion in the valve body 130a and the safety valve block 14, and biases the valve body 130a toward the water supply check valve 11 a. The biasing force of the spring 133a is weaker than the pressure of the water discharged from the water discharge passage 2a through the water piston portion 6a (see fig. 2).

The discharge check valve 13a having such a configuration switches between the open state and the closed state by reciprocating the valve body 130a in the valve shaft direction F. The open state of the discharge check valve 13a is a state that allows the water discharged from the water discharge passage 2a to flow toward the safety valve 15 a. The closed state of the discharge check valve 13a is a state in which the reverse flow of the water discharged from the water discharge passage 2a, that is, the flow of the discharged water from the safety valve 15a side to the water supply check valve 11a side is prevented. The discharge check valve 13a switches between the open state and the closed state to restrict the flow direction of the water discharged from the water discharge passage 2a side to the safety valve 15a side.

Specifically, in the discharge check valve 13a, the valve body 130a presses the pressure receiving portion 132a against the outlet end portion of the communication passage 12a by the biasing force of the spring 133 a. Thus, the valve body 130a blocks the communication between the internal passage 111a of the water supply check valve 11a and the internal passage 131a of the discharge check valve 13a, and the valve body is in the closed state. When the pressure receiving portion 132a receives the pressure of the water discharged from the water discharge passage 2a via the internal passage 111a of the valve body 11a and the communication passage 12a, the valve body 130a is moved in a direction against the urging force of the spring 133a by the pressure. Thereby, the valve body 130 separates the pressure receiving portion 132a from the communication passage 12a, and the communication passage 12a and the receiving port 134a communicate with each other via the internal passage 111a of the water supply check valve 11a and the internal passage 131a of the discharge check valve 13 a. Thus, the valve body 130a is in the open state. Subsequently, when the discharge of water from the water discharge passage 2a is completed, the valve body 130a brings the pressure receiving portion 132a close to the communication passage 12a by the biasing force of the spring 133a, and the above-described closed state is again achieved.

As shown in fig. 7, the relief valve 15a includes a valve body 150a, a spring 153a, and a valve stem 154 a. The valve body 150a is slidably attached to the stem 154a, and is housed in the relief valve block 14 so as to be capable of reciprocating in the valve axis direction F. An internal passage 151a is formed inside each of the valve body 150a and the stem 154 a. For example, as shown in fig. 7, the internal passage 151a communicates with the communication passage 14h communicating with the discharge check valve 13a on the tip side and communicates with the discharge port 16a on the rear end side. The discharge port 16a is formed in the lid portion 16. As described above, the downstream water injection pipe 42a communicating with the fuel injection valve 20A is connected to the discharge port 16 a. The internal passage 151a communicates with a branch passage 14a of a drain passage 14e (see fig. 6) in the relief valve block 14 at the distal end side so as to be openable and closable. The pressure receiving portion 152a is a portion that receives pressure for opening the valve body 150a, and is formed at the tip end portion (end portion on the discharge check valve 13a side) of the valve body 150 a. The pressure receiving portion 155a is a portion that receives the liquid pressure in a direction in which the valve body 150a is urged toward the discharge check valve 13a, and is, for example, a step portion that is formed in the valve body 150a on the opposite side of the pressure receiving portion 152a as shown in fig. 7.

For example, as shown in fig. 7, the spring 153a is attached to the stem 154a so as to be interposed between the rear end of the valve body 150a and the rear end of the stem 154 a. The spring 153a is in a state of contracting from a natural length between the rear end portion of the valve body 150a and the rear end portion of the stem 154a, and biases the valve body 150a toward the discharge check valve 13 a. The force resulting from the biasing force of the spring 153a and the force received by the pressure receiving portion 155a due to the pressure of the water discharged from the water discharge passage 2a is stronger than the force received by the pressure receiving portion 152a due to the pressure of the water discharged from the water discharge passage 2 a. The force of the spring 153a, which is the resultant force of the biasing force of the pressure receiving portion 155a and the force received by the pressure of the reverse flow liquid flowing back to the first water injection pump 41 from the fuel injection valve 20A through the downstream water injection pipe 42a, is weaker than the force received by the pressure receiving portion 152a by the pressure of the reverse flow liquid. As shown in fig. 7, the stem 154a is housed in the relief valve block 14 in a state where the spool 150a and the spring 153a are attached. At this time, the rear end portion of the stem 154a is sandwiched between the safety valve block 14 and the lid portion 16, whereby the stem 154a is fixed to the safety valve block 14. The valve rod 154a has both a function of guiding the valve body 150a to reciprocate in the valve axis direction F and a function of receiving the spring 153 a.

The relief valve 15a having such a structure switches between a closed state and an open state by reciprocating the valve body 150a in the valve shaft direction F. The closed state of the relief valve 15a is a state in which the internal passage 151a is closed with respect to the drain passage 14e (the branch passage 14a in fig. 7). The open state of the relief valve 15a is a state in which the internal passage 151a is open to the drain passage 14 e. The relief valve 15a is in the closed state described above by operating the valve body 150a by a resultant force of the biasing force of the spring 153a and the force acting on the pressure receiving portion 155a by the discharge pressure of the water. In this case, the relief valve 15a leads the water pressurized by the water piston portion 6a from the water discharge passage 2a to the discharge port 16a through the internal passage 151a, and leads from the discharge port 16a to the downstream water injection pipe 42a communicating with the fuel injection valve 20A. On the other hand, the relief valve 15a is set to the above-described open state by the pressure of the backflow liquid flowing back from the fuel injection valve 20A to the internal passage 151a through the downstream water injection pipe 42a (more specifically, the force acting on the pressure receiving portion 152a by the pressure of the backflow liquid) causing the valve body 150A to move in a direction against the biasing force of the spring 153 a. In this case, the safety valve 15a guides the reverse flow liquid to be discharged from the internal passage 151a to the outside of the first water injection pump 41 through the liquid discharge passage 14 e.

(Water discharge operation of Water injection Pump)

Next, a water discharge operation of the water injection pump according to the embodiment of the present invention will be described. Hereinafter, the water discharge operation of the first water injection pump 41 will be described as an example of the water discharge operation of the water injection pump according to the present embodiment, with reference to fig. 1 to 7 as appropriate.

In a stage before the water is discharged, the first water injection pump 41 is in a state (for example, a state shown in fig. 2) in which the hydraulic piston portion 7 is positioned at a predetermined reference position. At this time, water to be discharged is supplied from the water supply pump 61 shown in fig. 1 to the water discharge passages 2a, 2b, and 2c through the water supply pipe 62 and the like. For example, the water supply check valve 11a (see fig. 7) is switched from the closed state to the open state by the pressure of the water from the water supply pump 61. The water to be discharged is supplied to the water discharge passage 2a via the water supply check valve 11a in the open state. Similarly, the water to be discharged is supplied to the water discharge passages 2b and 2c through the water supply check valves 11b and 11c in the open state. Thereby, the water discharge passages 2a, 2b, and 2c are filled with the water to be discharged.

Next, when the first water injection pump 41 discharges water, hydraulic oil is supplied from the pressure accumulator 71 shown in fig. 1 to the hydraulic oil chamber 5a of the hydraulic cylinder 5 through the control valve 45 and the like. The hydraulic piston portion 7 receives the pressure of the hydraulic oil in the hydraulic oil chamber 5a, and moves (rises) toward the discharge ports 16a, 16b, and 16c by the pressure of the hydraulic oil. At this time, the hydraulic piston 7 moves the water piston portions 6a, 6b, and 6c toward the discharge ports 16a, 16b, and 16c together with the connecting portion 8 while overcoming the biasing force of the biasing portion 9. Thereby, the hydraulic piston portion 7 moves the water piston portions 6a, 6b, and 6c by the same amount of rise (preferably, the same volume) in the direction of pressing the water discharge passages 2a, 2b, and 2c, respectively.

The water piston portions 6a, 6b, and 6c pressurize the water in the water discharge passages 2a, 2b, and 2c (water to be discharged) while sliding in the water discharge passages 2a, 2b, and 2c by the same amount of movement (rise) due to the action of the hydraulic piston portion 7.

The water in the water discharge passage 2a is pressurized by the water piston 6a, and is pressure-fed from the water discharge passage 2a to the discharge port 16a side. Specifically, the water passes from the water discharge passage 2a through the internal passage 111a of the water supply check valve 11a and the communication passage 12a in a closed state to the discharge check valve 13 a. The water opens the discharge check valve 13a by the pressure, and flows into the internal passage 131a from the receiving port 134a of the discharge check valve 13 a. Then, the water passes through the internal passage 131a of the discharge check valve 13a and the communication passage 14h, and reaches the safety valve 15a in a closed state. The water passes through the internal passage 151a of the safety valve 15a and reaches the discharge port 16a without switching the closed state of the safety valve 15a to the open state. Then, the water flows into the downstream water injection pipe 42a from the discharge port 16a, and is injected into the first water injection position P1 of the fuel passage 22 of the fuel injection valve 20A through the downstream water injection pipe 42 a.

Similarly, the water pressurized by the water piston portion 6B passes through the water supply check valve 11B, the discharge check valve 13B, and the safety valve 15B in this order from the water discharge passage 2B to reach the discharge port 16B, and is injected from the discharge port 16B into the first water injection position P1 of the fuel passage 22 of the fuel injection valve 20B through the downstream water injection pipe 42B. The water pressurized by the water piston portion 6C passes through the water supply check valve 11C, the discharge check valve 13C, and the safety valve 15C in order from the water discharge passage 2C to the discharge port 16C, and is injected from the discharge port 16C into the first water injection position P1 of the fuel passage 22 of the fuel injection valve 20C through the downstream water injection pipe 42C.

The discharge of water by the first water injection pump 41 continues while the hydraulic oil is supplied to the hydraulic oil chamber 5a, that is, while the hydraulic piston portion 7 moves toward the discharge ports 16a, 16b, and 16c by the pressure of the hydraulic oil. Subsequently, when the supply of the hydraulic oil into the hydraulic oil chamber 5a is stopped, the discharge of the primary water by the first water injection pump 41 is completed. At this time, the hydraulic piston portion 7 moves from the current raised position to the original reference position while pushing out the hydraulic oil in the hydraulic oil chamber 5a (hydraulic oil used for the above-described discharge of water) from the hydraulic oil chamber 5a to the outside of the hydraulic cylinder 5 by the biasing force of the biasing portion 9. As the hydraulic piston 7 moves, the water piston portions 6a, 6b, and 6c move together with the connection portion 8 in a direction in which the compression of the water discharge passages 2a, 2b, and 2c (pressurization of water) is released, and return to the position before the water discharge is performed. When the water to be discharged is supplied from the water supply pump 61 to the water discharge passages 2a, 2b, and 2c through the water supply pipe 62 or the like, the water discharge passages 2a, 2b, and 2c return to a state filled with the water to be discharged.

(operation of safety valve)

Next, the operation of the safety valve of the water injection pump according to the embodiment of the present invention will be described. Fig. 8 is a diagram for explaining the operation of the safety valve of the water injection pump according to the embodiment of the present invention. Hereinafter, the operation of the safety valve 15a of the first water injection pump 41 will be described as an example of the operation of the safety valve of the present embodiment with reference to fig. 8. The operation of the safety valves 15b and 15c of the first water injection pump 41 is the same as the operation of the safety valve 15a described below.

When the first water injection pump 41 discharges water, the safety valve 15a is closed as shown in state S1 in fig. 8. In the safety valve 15a in the closed state, since the resultant force of the biasing force of the spring 153a and the force acting on the pressure receiving portion 155a by the discharge pressure of the water exceeds the force acting on the pressure receiving portion 152a by the discharge pressure of the water, the valve body 150a slides toward the tip end side of the stem 154a, and the pressure receiving portion 152a is brought into pressure contact with the outlet end portion of the communication passage 14 h. Thereby, the valve body 150a communicates the internal passage 131a (see fig. 7) of the discharge check valve 13a and the internal passage 151a of the relief valve 15a via the communication passage 14h, and blocks the communication between the internal passage 151a and the branch passage 14a of the drain passage 14e (see fig. 6). In this closed state, as described above, the water to be discharged is discharged from the discharge port 16a of the cap 16 through the communication passage 14h and the internal passage 151a of the safety valve 15 a.

On the other hand, when the reverse flow liquid from the fuel injection valve 20A flows back into the discharge port 16a through the downstream water injection pipe 42a, the reverse flow liquid passes through the internal passage 151a of the relief valve 15a from the discharge port 16a and enters the communication passage 14h as shown in state S2 in fig. 8. The reverse flow liquid fills the communication passage 14h and the internal passage 131a of the discharge check valve 13a (see fig. 7), and applies pressure to the pressure receiving portion 152a and the pressure receiving portion 155a of the valve body 150a of the relief valve 15 a. The force acting on the pressure receiving portion 152a by the pressure of the back flow liquid exceeds the resultant force of the force acting on the pressure receiving portion 155a by the pressure of the back flow liquid and the biasing force of the spring 153 a. Therefore, the relief valve 15a is switched from the closed state to the open state by the force acting on the pressure receiving portion 152 a. Specifically, in the relief valve 15a, the valve body 150a is moved in a direction against the biasing force of the spring 153a by the force acting on the pressure receiving portion 152a by the pressure of the aforementioned back-flow liquid. Thereby, the valve body 150a is separated from the communication passage 14h while sliding toward the rear end side of the stem 154a, and the internal passage 151a of the relief valve 15a and the branch passage 14a of the drain passage 14e are communicated with each other. The safety valve 15a thus opened guides the reverse flow liquid filling the internal passage 151a, the communication passage 14h, and the like from the branch passage 14a to the drain passage 14e, and discharges the reverse flow liquid from the drain port 14f (see fig. 6) to the outside of the water injection pump through the drain passage 14 e. This allows the safety valve 15a to release the excessively high pressure of the reverse flow liquid to the outside of the water injection pump.

Subsequently, when the discharge of the reverse flow liquid to the outside of the water injection pump is completed, the safety valve 15a returns from the above-described open state to the closed state. At this time, the valve body 150a approaches the communication passage 14h by the biasing force of the spring 153a, and communicates the internal passage 131a of the discharge check valve 13a and the internal passage 151a of the relief valve 15a via the communication passage 14h again, and blocks the communication between the internal passage 151a and the branch passage 14a of the drain passage 14 e.

As described above, in the water injection pump according to the embodiment of the present invention, the water discharge passage is configured to communicate with the water injection pipe of the fuel injection valve connected to the cylinder, the water piston portion that pressurizes water and discharges the water to the fuel injection valve side is provided so as to be capable of reciprocating in the water discharge passage, the safety valve having the internal passage communicating with the water injection pipe is disposed between the water discharge passage and the water injection pipe along the piston shaft of the water piston portion in the water discharge passage, and the safety valve is led to the outside of the water injection pump through the liquid discharge passage. Further, the safety valve guides the water pressurized by the water piston portion from the water discharge passage to the water injection pipe through the internal passage in a closed state in which the internal passage is closed with respect to the liquid discharge passage, and when a reverse flow liquid flows from the fuel injection valve to the internal passage through the water injection pipe, the safety valve opens the internal passage to the liquid discharge passage by the pressure of the reverse flow liquid and guides the reverse flow liquid to be discharged from the internal passage to the outside of the water injection pump through the liquid discharge passage.

With the above configuration, the pressure of the reverse flow liquid can be released to the outside of the water injection pump by the action of the safety valve without impairing the water discharge function of the fuel injection valve of the water injection pump, and the safety valve can be disposed in the water injection pump to suppress an increase in the width of the water injection pump. Therefore, without reinforcing the pressure-resistant structure of the water injection pump, excessive pressurization due to a reverse flow liquid such as fuel that flows back from the fuel injection valve can be avoided, and the water injection pump can be downsized. As a result, the water injection pump can be prevented from being damaged by excessive pressurization due to the backflow liquid, fuel leakage due to damage of the water injection pump can be prevented, and an increase in the space (footprint) required for the arrangement of the water injection pump can be suppressed, thereby realizing a water injection pump of a device scale suitable for the arrangement around the cylinder of the marine diesel engine.

In the water injection pump according to the embodiment of the present invention, the discharge check valve that restricts the flow direction of the water discharged from the water discharge passage to the direction from the water discharge passage side toward the relief valve side is disposed between the relief valve and the water discharge passage along the piston shaft of the water piston portion. Therefore, even if the discharge check valve is disposed in the water injection pump, the discharge check valve can be protected from the pressure of the reverse flow liquid by the action of the safety valve while suppressing an increase in the width of the water injection pump. As a result, the discharge check valve can be prevented from being damaged by the excessive pressurization due to the backflow liquid without impairing the miniaturization of the water injection pump.

In the water injection pump according to the embodiment of the present invention, the water supply check valve that restricts the flow direction of the water supplied into the water discharge passage through the water supply pipe is disposed between the safety valve and the water discharge passage (more specifically, between the discharge check valve and the water discharge passage) along the piston shaft of the water piston portion. Therefore, even if the water supply check valve is disposed in the water injection pump, the water supply check valve can be protected from the pressure of the backflow liquid by the action of the safety valve while suppressing an increase in the width of the water injection pump. As a result, the water supply check valve can be prevented from being damaged by the excessive pressurization of the reverse flow liquid without impairing the miniaturization of the water injection pump.

In the water injection pump according to the embodiment of the present invention, a plurality of safety valves are disposed in the water injection pump in correspondence with a plurality of water discharge passages, each of the liquid discharge passages is composed of a plurality of branch passages communicating with the plurality of safety valves and a merging passage merging with the plurality of branch passages and communicating with the outside of the water injection pump. Therefore, as compared with the case where a plurality of drain passages leading to the outside of the water filling pump are formed so as to extend from each of the plurality of safety valves, the occupied portion of the drain passages in the water filling pump can be reduced. As a result, the liquid discharge passage can be easily formed in the water injection pump, and the water injection pump can be more downsized.

In the water injection pump according to the embodiment of the present invention, the water supply check valve block having the water supply check valve therein, the discharge check valve block having the discharge check valve therein, and the safety valve block having the safety valve and the liquid discharge passage therein are detachably attached to the upper portion of the water cylinder having the water discharge passage and the water piston portion therein. Therefore, the water supply check valve, the discharge check valve, the safety valve, and the liquid discharge passage can be easily provided in the water injection pump, and the respective maintenance and replacement of the water supply check valve, the discharge check valve, the safety valve, and the liquid discharge passage can be easily performed by the respective block units of the water supply check valve block, the discharge check valve block, and the safety valve block.

In the above-described embodiment, the water injection pump that injects water into each of the fuel passages of the three fuel injection valves 20A, 20B, and 20C provided in one cylinder is illustrated, but the present invention is not limited to this. For example, the water injection pump according to the present invention may be configured to inject water into each of the fuel passages of one or more (at least one) fuel injection valves provided in one cylinder. Accordingly, the number of the safety valves disposed in the water injection pump is not limited to the three described above, and may be one or more.

In the above-described embodiment, the water injection pump including the water supply check valve and the discharge check valve is exemplified, but the present invention is not limited thereto. For example, the water supply check valve may be provided in a water supply pipe that communicates the water injection pump and the water supply pump. Further, the discharge check valve may be provided in a water injection pipe that communicates the water injection pump and the fuel injection valve.

In the above-described embodiment, the water injection pump has been described as an example in which the three water piston portions 6a, 6b, and 6c are operated by the action of the single hydraulic piston portion 7, but the present invention is not limited to this. For example, the water injection pump according to the present invention may be configured to operate one or more water piston portions by the action of one hydraulic piston portion. That is, in the present invention, the number of the water piston portions and the number of the water discharge passages may be set so as to correspond to the number of the fuel injection valves to be filled with water provided in one cylinder. Similarly, the number of discharge check valves and water supply check valves disposed in the water injection pump is not limited to the three described above, and may be one or more according to the number of fuel injection valves to be injected in one cylinder.

The present invention is not limited to the above-described embodiments, and a configuration in which the above-described respective components are appropriately combined is also included in the present invention. In addition, other embodiments, examples, operation techniques, and the like, which are made by those skilled in the art based on the above-described embodiments, are all included in the scope of the present invention.

Industrial applicability of the invention

As described above, the water injection pump according to the present invention is useful for injecting water into the fuel injection valve, and is particularly suitable for a water injection pump that can avoid excessive pressurization of a back-flow liquid such as fuel that flows back from the fuel injection valve and can achieve a reduction in the size of the device.

Description of the symbols

1 Water vat

2a, 2b, 2c water discharge passage

4 inner space

5 Hydraulic cylinder

5a working oil chamber

6a, 6b, 6c water piston part

7 hydraulic piston part

8 connecting part

9 force application part

10 water supply check valve block

11a, 11b, 11c water supply check valve

110a valve core

111a, 111b, 111c internal passages

112a pressure receiving portion

113a spring

12-discharge check valve block

12a communication path

13a, 13b, 13c discharge check valve

130a valve core

131a, 131b, 131c internal passages

132a pressure receiving portion

133a spring

134a receiving port

14 safety valve block

14a, 14b, 14c branch passages

14d confluence passage

14e liquid discharge path

14f Drain

14h communication path

15a, 15b, 15c safety valve

150a valve core

151a, 151b, 151c internal passages

152a pressure receiving portion

153a spring

154a valve stem

155a pressure receiving portion

16 cover part

16a, 16b, 16c discharge port

17 mounting bolt

18 plug

20A, 20B, 20C fuel injection valve

21 jet orifice

22 fuel path

23 internal passages

24a, 24b check valve

30 fuel pressure feed system

31 fuel injection pump

32 fuel injection pipe

32a, 32b, 32c branch pipes

33 branching part

35 control valve

40 downstream side water injection system

41 first water injection pump

42a, 42b, 42c downstream water injection pipe

45 control valve

50 upstream side water injection system

51 second water injection pump

52a, 52b, 52c upstream side water injection pipe

55 control valve

61 water supply pump

62 Water supply pipe

62a, 62b branch pipe

71 pressure accumulating part

72 high pressure pump

81 detection part

82 control part

100 fuel injection system

CL1, CL2, CL3 piston shaft

Direction of valve axis F

P1 first Water injection position

P2 second Water injection position