阅读说明：本技术 二冲程柴油机及其进气方法 (Two-stroke diesel engine and air intake method thereof ) 是由 覃壮革 沈捷 廖升友 覃文 于 2021-04-28 设计创作，主要内容包括：本发明公开了一种二冲程柴油机及其进气方法,二冲程柴油机包括气缸盖、气缸体以及设置在气缸体的缸筒内的活塞,气缸盖包括上进气道、上层进气道及下层进气道；上进气道的一端与进气管的上出气口连通,另一端通过上进气门与缸筒连通；上层进气道的一端与进气管的上出气口连通；下层进气道的一端与进气管的下出气口连通；其中上层进气道的另一端与下层进气道的另一端通过短进气门连通；气缸体包括下进气道,下进气道的一端与进气管的下出气口连通。本发明的二冲程柴油机采用增加上进气道以及上下层进气道的换气方式,使得柴油机废气扫除更彻底,新鲜空气填充更充分,提高柴油机热效率,从而提高柴油机的经济性、动力性,降低柴油机的热负荷。(The invention discloses a two-stroke diesel engine and an air inlet method thereof, wherein the two-stroke diesel engine comprises a cylinder cover, a cylinder body and a piston arranged in a cylinder barrel of the cylinder body, wherein the cylinder cover comprises an upper air inlet channel, an upper air inlet channel and a lower air inlet channel; one end of the upper air inlet channel is communicated with an upper air outlet of the air inlet pipe, and the other end of the upper air inlet channel is communicated with the cylinder barrel through the upper air inlet valve; one end of the upper layer air inlet channel is communicated with an upper air outlet of the air inlet pipe; one end of the lower air inlet channel is communicated with a lower air outlet of the air inlet pipe; the other end of the upper layer air inlet channel is communicated with the other end of the lower layer air inlet channel through a short inlet valve; the cylinder block includes lower intake duct, and the one end of lower intake duct communicates with the lower gas outlet of intake pipe. The two-stroke diesel engine adopts the ventilation mode of adding the upper air inlet passage and the upper and lower air inlet passages, so that the waste gas of the diesel engine is more thoroughly swept, the fresh air is more fully filled, the heat efficiency of the diesel engine is improved, the economical efficiency and the dynamic property of the diesel engine are improved, and the heat load of the diesel engine is reduced.)

1. A two-stroke diesel engine comprising a cylinder head, a cylinder block, and pistons disposed within bores of the cylinder block, the cylinder head comprising:

one end of the upper air inlet channel is communicated with an upper air outlet of the air inlet pipe, and the other end of the upper air inlet channel is communicated with the cylinder barrel through an upper air inlet valve;

an upper layer air inlet passage, one end of which is communicated with the upper air outlet of the air inlet pipe;

one end of the lower layer air inlet channel is communicated with a lower air outlet of the air inlet pipe;

the other end of the upper-layer air inlet channel is communicated with the other end of the lower-layer air inlet channel through a short inlet valve;

the cylinder block includes lower inlet channel, its one end with the intake pipe lower gas outlet intercommunication.

2. The two-stroke diesel engine of claim 1, wherein the upper intake port and the lower intake port are stacked up and down to form a dual intake port when viewed perpendicular to the central axis of the piston.

3. The two-stroke diesel engine of claim 2 wherein said upper intake port is positioned alongside said dual intake port as viewed along said piston's central axis.

4. The two-stroke diesel engine of claim 1 wherein said cylinder block further includes a plurality of lower intake ports uniformly circumferentially disposed in a lower portion of said cylinder bore, said plurality of lower intake ports communicating with the other end of said lower intake duct.

5. A two-stroke diesel engine as claimed in claim 4 wherein the extension of the centre line of each said lower inlet port is tangential to the circumference at one half of the radius of said cylinder.

6. A two-stroke diesel engine as set forth in claim 4 wherein the distance from the lower edge of said plurality of lower intake ports to the top surface of said cylinder is less than the stroke of said piston.

7. An intake method applied to a two-stroke diesel engine according to any one of claims 1 to 6, characterized by comprising:

the piston moves downwards, the exhaust valve is opened, and pressure waste gas in the cylinder barrel is exhausted from the exhaust valve;

when the piston continues to move downwards to enable the lower air inlets to be opened initially, the short inlet valve is opened, pressurized air or mixed air enters the upper-layer air inlet channel from the upper air outlet of the air inlet pipe, enters the cylinder barrel through the short inlet valve, the lower-layer air inlet channel, the lower air outlet of the air inlet pipe, the lower air inlet channel and the lower air inlets, forms a direct-current sweeping air flow which rotates upwards in the cylinder barrel, and further sweeps pressure waste gas in the cylinder barrel and is discharged from the exhaust valve; and

the piston descends to a bottom dead center, after the lower air inlets are completely opened, the piston starts to ascend until the lower air inlets are completely closed, and the short air inlet is closed.

8. The intake method of claim 7, further comprising:

before the lower air inlets are opened initially, the upper air inlet is opened, pressurized air or mixed air enters the cylinder barrel from the upper air outlet of the air inlet pipe through the upper air inlet and the upper air inlet, and pressure waste gas in the cylinder barrel is swept and discharged from the exhaust valve; and

after the short intake valve closes and a delay period, the upper intake valve and the exhaust valve close.

Technical Field

The invention relates to the field of engines, in particular to a two-stroke diesel engine and an air intake method thereof.

Background

Modern four-stroke and two-stroke diesel engines are successfully used in various fields, have respective characteristics, and are generally used in large low-speed diesel engines for ships, while the middle and high-speed diesel engines are mostly used in four-stroke engines. Under the same cylinder size and rotating speed, the power of the two-stroke power generator is increased by about 60-70% compared with that of a four-stroke engine.

In the prior art, a two-stroke diesel engine completes the processes of air intake, compression, work application and exhaust of a four-stroke diesel engine in two strokes, and a scavenging system of the two-stroke diesel engine is a foundation. A scavenging mechanism of a two-stroke diesel engine mainly comprises a crankcase scavenging structure and a scavenging pump scavenging structure. The latter forcibly introduces air from the scavenging port. For a supercharged two-stroke diesel engine, the compressor can be used directly to supply fresh charge for scavenging.

As shown in fig. 1, the two-stroke diesel engine has no intake valve and no exhaust valve, but has scavenging port and exhaust port in the lower part of the cylinder; or a scavenging port and an exhaust valve mechanism are arranged, and the gas distribution is completed by the matching of the piston and the gas port. In order to exhaust the burnt exhaust gas and to fill the cylinder with fresh air, a two-stroke diesel engine must be equipped with a dedicated scavenging pump (supercharger) driven by a moving part and a scavenging tank for storing pressurized air.

Air exchange process of the two-stroke diesel engine: after the pressure of air is increased by the scavenging pump, the air enters the cylinder through an air chamber arranged outside the cylinder and a plurality of small holes on the cylinder sleeve, and the waste gas is discharged through an exhaust valve on the cylinder cover.

As shown in fig. 2, the two-stroke diesel engine mainly has three different forms of scavenging systems or scavenging schemes, i.e. a cross flow, b reflux and c direct flow.

Two-stroke diesel engines are typically uniflow scavenged from exhaust valve-scavenging port

As shown in figure 3, a circle of air inlets are uniformly distributed at the lower part of the cylinder, and an exhaust valve is arranged on the cylinder cover. Air enters the cylinder from an air inlet end at the lower part of the cylinder, and drives exhaust gas upwards along the center line of the cylinder to be discharged out of the cylinder from an exhaust valve on the cylinder cover.

Regardless of the scavenging method and the scavenging structure, the current two-stroke diesel engine has the following disadvantages:

(1) two-stroke diesel engines are more fuel-consuming and, because of their lower fuel utilization, a considerable portion of the fuel is discharged without or under combustion, so that the hydrocarbons in the exhaust gas are several times higher than in the four-stroke cycle.

(3) The scavenging process is short in time, scavenging is not complete as the four-stroke engine, and the supercharger is depended on.

(4) The temperature of the piston, cylinder head, cylinder and air valve of the two-stroke diesel engine is much higher than that of the four-stroke engine.

(5) Poor ventilation quality and low thermal efficiency.

(6) The thermal load is high.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

The invention aims to provide a two-stroke diesel engine, which adopts a ventilation mode of increasing an upper air inlet passage and an upper and lower layer air inlet passages, so that the waste gas of the diesel engine is more thoroughly swept, the fresh air is more fully filled, the heat efficiency of the diesel engine is improved, the economical efficiency and the dynamic property of the diesel engine are improved, and the heat load of the diesel engine is reduced.

Another object of the present invention is to provide a method of air induction for a two-stroke diesel engine.

In order to achieve the purpose, the invention provides a two-stroke diesel engine, which comprises a cylinder cover, a cylinder body and a piston arranged in a cylinder barrel of the cylinder body, wherein the cylinder cover comprises an upper air inlet channel, an upper air inlet channel and a lower air inlet channel; one end of the upper air inlet channel is communicated with an upper air outlet of the air inlet pipe, and the other end of the upper air inlet channel is communicated with the cylinder barrel through the upper air inlet valve; one end of the upper layer air inlet channel is communicated with an upper air outlet of the air inlet pipe; one end of the lower air inlet channel is communicated with a lower air outlet of the air inlet pipe; the other end of the upper layer air inlet channel is communicated with the other end of the lower layer air inlet channel through a short inlet valve; the cylinder block includes lower intake duct, and the one end of lower intake duct communicates with the lower gas outlet of intake pipe.

In a preferred embodiment, the upper inlet channel and the lower inlet channel are stacked up and down to form a double-layer inlet channel when viewed along a direction perpendicular to a central axis of the piston.

In a preferred embodiment, the upper intake duct is arranged alongside the double intake duct, viewed in the direction of the centre axis of the piston.

In a preferred embodiment, the cylinder block further includes a plurality of lower intake ports, which are uniformly provided around the lower portion of the cylinder tube, and the plurality of lower intake ports communicate with the other end of the lower intake duct.

In a preferred embodiment, the extension of the centre line of each lower inlet opening is tangent to the circumference at half the radius of the cylinder.

In a preferred embodiment, the distance from the lower edge of the lower inlet ports to the top surface of the cylinder is smaller than the stroke of the piston.

In order to achieve the other object, the present invention further provides an intake method applied to the two-stroke diesel engine as described above, the intake method comprising: the piston moves downwards, the exhaust valve is opened, and pressure waste gas in the cylinder barrel is discharged from the exhaust valve; when the piston continues to move downwards to enable the plurality of lower air inlets to be initially opened, the short inlet valve is opened, pressurized air or mixed gas enters the upper-layer air inlet channel from the upper air outlet of the air inlet pipe and enters the cylinder barrel through the short inlet valve, the lower-layer air inlet channel, the lower air outlet of the air inlet pipe, the lower air inlet channel and the plurality of lower air inlets, a direct-current sweeping air flow which rotates upwards is formed in the cylinder barrel, and pressure waste gas in the sweeping cylinder barrel is further discharged from the exhaust valve; and the piston descends to the bottom dead center, after the lower air inlets are completely opened, the piston starts to ascend until the lower air inlets are completely closed, and the short air inlet is closed.

In a preferred embodiment, the air intake method further comprises: before the lower air inlets are opened initially, the upper air inlet is opened, pressurized air or mixed air enters the cylinder barrel from the upper air outlet of the air inlet pipe through the upper air inlet and the upper air inlet, and pressure waste gas in the cylinder barrel is purged and discharged from the exhaust valve; and after the short intake valve closes and a delay, the upper intake valve and the exhaust valve close.

Compared with the prior art, the two-stroke diesel engine and the air intake method thereof have the following beneficial effects: the air exchange mode of increasing the upper air inlet channel and the upper and lower air inlet channels is adopted, so that the exhaust gas of the diesel engine is more thoroughly swept, the fresh air is more fully filled, the heat efficiency of the diesel engine is improved, the economical efficiency and the dynamic performance of the diesel engine are improved, and the heat load of the diesel engine is reduced. The problems of incomplete scavenging and low charging efficiency of the two-stroke diesel engine are solved.

Drawings

FIG. 1 is a schematic diagram of a crankcase scavenged two-stroke engine according to one embodiment of the prior art;

FIG. 2 is a schematic view of a scavenging scheme for a two-stroke diesel engine according to one embodiment of the prior art;

FIG. 3 is a schematic diagram of a two-stroke diesel engine with uniflow scavenging of the valve windows according to an embodiment of the present invention;

FIG. 4 is a schematic front view of a two-stroke diesel engine according to an embodiment of the present invention;

FIG. 5 is a schematic cross-sectional view taken at A-A of FIG. 4;

FIG. 6 is a schematic cross-sectional view taken at C-C of FIG. 5;

FIG. 7 is a schematic cross-sectional view taken at D-D of FIG. 5;

FIG. 8 is a schematic cross-sectional view taken at E-E of FIG. 5;

FIG. 9 is a schematic cross-sectional view taken at F-F of FIG. 5;

FIG. 10 is a schematic cross-sectional view taken at G-G of FIG. 8;

FIG. 11 is a schematic cross-sectional view taken at H-H of FIG. 8;

FIG. 12 is a cross-sectional structural view of a lower intake port according to an embodiment of the present invention;

FIG. 13 is a conceptual illustration of valve timing for a two-stroke diesel engine according to an embodiment of the present invention;

FIG. 14 is a schematic view of the air intake principle of a two-stroke diesel engine according to an embodiment of the present invention;

fig. 15 is a schematic view of the intake principle of a two-stroke diesel engine according to an embodiment of the present invention.

Description of the main reference numerals:

1-cylinder cover, 11-upper air inlet channel, 12-upper air inlet channel, 13-lower air inlet channel, 2-cylinder body, 21-lower air inlet channel, 22-lower air inlet channel, 23-cylinder barrel, 3-piston, 4-air inlet channel, 5-short air inlet valve, 6-upper air inlet valve and 7-exhaust valve.

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

As shown in fig. 4 to 11, a two-stroke diesel engine according to a preferred embodiment of the present invention includes a cylinder head 1, a cylinder block 2, and a piston 3 disposed in a cylinder bore 23 of the cylinder block 2. The cylinder head 1 includes an upper intake duct 11, an upper intake duct 12, and a lower intake duct 13. The cylinder block 2 includes a lower intake passage 21 and a plurality of lower intake ports 22. One end of the upper air inlet channel 11 is communicated with an upper air outlet of the air inlet pipe 4, and the other end is communicated with the cylinder barrel 23 through the upper air inlet valve 6. One end of the upper layer air inlet channel 12 is communicated with an upper air outlet of the air inlet pipe 4. Wherein the other end of the upper intake passage 12 is communicated with the other end of the lower intake passage 13 through the short intake valve 5. One end of the lower air inlet channel 21 is communicated with a lower air outlet of the air inlet pipe 4. One end of the lower layer air inlet channel 13 is communicated with a lower air outlet of the air inlet pipe 4. A plurality of lower intake ports 22 are uniformly annularly provided in a lower portion of the cylinder tube 23, and the plurality of lower intake ports 22 communicate with the other end of the lower intake duct 21.

Referring to fig. 5 to 11, in some embodiments, the upper intake duct 12 and the lower intake duct 13 are stacked up and down to form a double-layer intake duct when viewed along a direction perpendicular to a central axis of the piston 3. Looking along the central axis direction of the piston 3, the upper air inlet channel 11 and the double-layer air inlet channel are arranged side by side.

In some embodiments, the cross-sectional shapes of the upper intake duct 11 and the lower intake duct 13 of the present embodiment are approximately circular, and the cross-sectional shape of the upper intake duct 12 is approximately square, but the present invention is not limited thereto.

Referring to fig. 6 and 12, in some embodiments, the extension of the center line of each lower intake port 22 is tangent to the circumference at one-half of the radius of the cylinder 23. This arrangement makes it easier to discharge the pressurized exhaust gas remaining inside the cylinder 23 in order to facilitate the formation of a straight-flow sweep gas stream that rotates upward from the bottom of the cylinder 23 into the cylinder 23.

As shown in fig. 14 to 15, in some embodiments, the distance from the lower edge of the plurality of lower intake ports 22 to the top surface of the cylinder 23 is smaller than the stroke of the piston 3. That is, when the piston 3 travels to the bottom dead center, it is possible to ensure that the lower intake ports 22 are fully opened.

In some embodiments, both the piston 3 and the short intake valve 5 may control the opening and closing of the intake air. The arrangement significance of the short inlet valve 5 is that: when the piston 3 moves up and down in the cylinder 23, when a circle of tangential downward air inlet 22 on the cylinder 23 is positioned below a piston ring, if no short air inlet valve exists, high-pressure air or mixed gas enters a crankcase through a gap between the outer circle of the piston skirt and the cylinder 23, the pressure of the crankcase is increased, and a large amount of blow-by gas and oil are blown by an engine respirator. The meaning of the short inlet valve 5 of the present solution is that in this case, the lower inlet air is cut off, ensuring that no high pressure gas enters the crankcase.

Referring to fig. 13 and fig. 14 to 15, an intake method according to a preferred embodiment of the present invention is applied to a two-stroke diesel engine as described above, and includes: the piston 3 moves downwards, an exhaust valve 7 (a double exhaust valve type diesel engine in the embodiment) is opened, and pressure waste gas in the cylinder 23 is exhausted from the exhaust valve 7; when the piston 3 continues to move downwards to enable the plurality of lower air inlets 22 to be opened initially, the short inlet valve 5 is opened, pressurized air or mixed gas enters the upper-layer air inlet channel 12 from the upper air outlet of the air inlet pipe 4 and enters the cylinder barrel 23 through the short inlet valve 5, the lower-layer air inlet channel 13, the lower air outlet of the air inlet pipe 4, the lower air inlet channel 21 and the plurality of lower air inlets 22, upward rotating direct-current scavenging air flow is formed in the cylinder barrel 23, and pressure waste gas in the scavenging cylinder barrel 23 is further exhausted from the exhaust valve 7; and the piston 3 descends to the bottom dead center, after the lower air inlets 22 are completely opened, the piston 3 starts ascending until the lower air inlets 22 are completely closed, and the short air inlet valve 5 is closed.

In some embodiments, the method of air intake further comprises: before the lower air inlets 22 are opened initially, the upper air inlet 6 is opened, pressurized air or mixed air enters the cylinder barrel 23 from the upper air outlet of the air inlet pipe 4 through the upper air inlet pipe 11 and the upper air inlet 6, and pressure waste gas in the purging cylinder barrel 23 is exhausted from the exhaust valve 7; and after the short intake valve 5 is closed and delayed for a while, the upper intake valve 6 and the exhaust valve 7 are closed.

In some embodiments, the opening time of the upper intake valve 6 and the closing time of the upper intake valve 6 and the exhaust valve 7 are only illustrative, and the invention is not limited thereto. The closing times of the upper intake valve 6 and the exhaust valve 7 may or may not be simultaneous. And which of the closing times of the upper intake valve 6 and the exhaust valve 7 is before and after, the present invention is not particularly limited herein and may be determined according to the circumstances and calculation.

In summary, the two-stroke diesel engine and the air intake method thereof have the following advantages that the air distribution mechanism provided by the invention is provided with the air inlet valve on the cylinder cover to increase the air intake quantity, and meanwhile, the air inlet at the lower part is arranged along the circumferential tangent line of the cylinder hole, so that the fresh charge entering the cylinder rotates at a high speed to form an air cushion piston, the excessive mixing of the fresh charge and the waste gas is avoided, the waste gas is pushed out in an upward acceleration manner, and the air exchange quality is improved. The cylinder cover is provided with an exhaust valve, scavenging is started from the lower part of the cylinder sleeve, exhaust is performed from the top of the cylinder sleeve, scavenging airflow moves along the axis of the cylinder, and the quality of scavenging is improved. Because the scavenging holes can be arranged along the periphery of the whole cylinder, under the condition that the total scavenging sectional area is not changed, holes can be opened more to reduce the height of the air holes, thereby reducing the loss of work stroke. The mode also enables the scavenging air to uniformly cool the piston and the stress is balanced. The adoption increases the mode of taking a breath of last air inlet and upper and lower layer intake duct like this for diesel engine exhaust gas sweeps more thoroughly, and fresh air fills more fully, improves diesel engine thermal efficiency, thereby improves diesel engine's economic nature, dynamic nature, reduces the heat load of diesel engine. The problems of incomplete scavenging and low charging efficiency of the two-stroke diesel engine are solved.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.