阅读说明：本技术 一种限压阀装置结构、调压柱塞以及液压泵 (Pressure limiting valve device structure, pressure regulating plunger and hydraulic pump ) 是由 吕建林 李耀军 纪忠阁 程良星 于 2020-05-27 设计创作，主要内容包括：本申请公开了一种限压阀装置、调压柱塞以及液压泵,所述限压阀装置包括设置在机体内的柱塞容置腔,以及设置在柱塞容置腔内部的调压柱塞和弹性部件；调压柱塞包括第一头部、第二头部、以及连接在第一头部和第二头部之间的连接部；第一头部、第二头部外壁面分别与柱塞容置腔内壁面相配；第一头部将设置在柱塞容置腔内的压力反馈腔和高压油腔分开；第二头部将设置在柱塞容置腔内的高压油腔和低压油腔分开；弹性部件的一端与第二头部的底部抵靠,另一端与低压油腔的内壁抵靠；第一头部的侧壁设置有进油口,第二头部位于低压油腔的底部设置有出油口,进油口和出油口通过调压柱塞内部设置的油道相连；压力反馈腔与需要获得油压反馈的油压位置相通。(The application discloses a pressure limiting valve device, a pressure regulating plunger and a hydraulic pump, wherein the pressure limiting valve device comprises a plunger accommodating cavity arranged in a machine body, and the pressure regulating plunger and an elastic component which are arranged in the plunger accommodating cavity; the pressure regulating plunger comprises a first head part, a second head part and a connecting part connected between the first head part and the second head part; the outer wall surfaces of the first head part and the second head part are respectively matched with the inner wall surface of the plunger accommodating cavity; the first head part separates a pressure feedback cavity and a high-pressure oil cavity which are arranged in the plunger accommodating cavity; the second head part separates a high-pressure oil chamber and a low-pressure oil chamber which are arranged in the plunger accommodating chamber; one end of the elastic component is abutted against the bottom of the second head part, and the other end of the elastic component is abutted against the inner wall of the low-pressure oil cavity; the side wall of the first head part is provided with an oil inlet, the bottom of the second head part, which is positioned in the low-pressure oil cavity, is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger; the pressure feedback cavity is communicated with an oil pressure position needing to obtain oil pressure feedback.)

1. A pressure limiting valve apparatus, comprising: the pressure regulating plunger piston and the elastic component are arranged in the plunger piston accommodating cavity;

the pressure regulating plunger comprises a first head part, a second head part and a connecting part connected between the first head part and the second head part; the outer wall surfaces of the first head part and the second head part are respectively matched with the inner wall surface of the plunger accommodating cavity; the first head part separates a pressure feedback cavity and a high-pressure oil cavity which are arranged in the plunger accommodating cavity; the second head portion separates a high-pressure oil chamber and a low-pressure oil chamber provided in the plunger accommodating chamber; one end of the elastic component is abutted against the bottom of the second head part, and the other end of the elastic component is abutted against the inner wall of the low-pressure oil cavity;

the side wall of the first head is provided with an oil inlet, the bottom of the second head, which is positioned in the low-pressure oil cavity, is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger; the pressure feedback cavity is communicated with an oil pressure position needing to obtain oil pressure feedback.

2. The pressure limiting valve assembly as recited in claim 1 wherein the resilient member and pressure regulating plunger are disposed axially of the plunger receiving cavity.

3. The pressure limiting valve assembly as recited in claim 2 wherein the oil passage provided within the pressure regulating plunger comprises: the oil inlet oil duct and the oil outlet oil duct are communicated with each other; wherein the content of the first and second substances,

the oil inlet oil duct is arranged at the first head part along the radial direction of the plunger accommodating cavity and is communicated with the oil inlet;

the oil outlet passage is arranged at the position of the connecting part along the axial direction of the plunger accommodating cavity; and is communicated with the oil outlet.

4. The pressure limiting valve device as recited in claim 3 wherein a side wall surface of the first head portion that is close to the high-pressure oil chamber abuts against an inner wall surface of the plunger accommodating chamber;

the side wall surface of the first head abutting against the inner wall surface of the plunger accommodating cavity at least comprises a pair of symmetrically arranged oil inlets, and each pair of oil inlets corresponds to one oil inlet duct.

5. A pressure limiting valve arrangement as claimed in claim 4 wherein the side wall surface of the first head portion is provided with an annular groove in which the symmetrically disposed oil inlets are disposed.

6. A pressure regulating plunger, comprising a first head, a second head, and a connecting portion connected between the first head and the second head;

the side wall of the first head is provided with an oil inlet, the bottom of the second head is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger.

7. The pressure regulating plunger of claim 6, wherein the oil passages provided therein comprise: the oil inlet oil duct and the oil outlet oil duct are communicated with each other; wherein the content of the first and second substances,

the oil inlet oil duct is arranged at the first head part along the radial direction of the first head part and is communicated with the oil inlet;

the oil outlet passage is arranged at the position of the connecting part along the axial direction of the connecting part; and is communicated with the oil outlet.

8. The pressure regulating plunger of claim 7, wherein the side wall surface of the first head portion at least comprises a pair of symmetrically arranged oil inlets, and each pair of oil inlets corresponds to one oil inlet channel.

9. The pressure regulating plunger of claim 8, wherein the sidewall surface of the first head portion is provided with an annular recess, and the symmetrically disposed oil inlets are disposed in the annular recess.

10. A hydraulic pump, comprising: a pump body and a plunger type pressure limiting device;

the pump body comprises an oil inlet cavity and an oil outlet cavity;

the plunger type pressure limiting device comprises a plunger containing cavity, and the plunger containing cavity comprises a low-pressure oil cavity, a high-pressure oil cavity and a pressure feedback cavity;

the oil inlet cavity is communicated with the low-pressure oil cavity; the oil outlet cavity is communicated with the high-pressure oil cavity and an oil outlet pipe arranged at the tail end of the pump body; the pressure feedback cavity is communicated with an oil pressure position which is arranged at the tail end of an oil way of the oil outlet pipe and obtains oil pressure feedback;

the plunger type pressure limiting device also comprises a pressure regulating plunger and an elastic component which are arranged in the plunger accommodating cavity;

the plunger type pressure limiting device comprises: the pressure regulating plunger and the elastic component are arranged in the plunger accommodating cavity; the pressure regulating plunger comprises a first head part, a second head part and a connecting part connected between the first head part and the second head part; the outer wall surfaces of the first head part and the second head part are respectively matched with the inner wall surface of the plunger accommodating cavity; the first head part separates a pressure feedback cavity and a high-pressure oil cavity which are arranged in the plunger accommodating cavity; the second head portion separates a high-pressure oil chamber and a low-pressure oil chamber provided in the plunger accommodating chamber; one end of the elastic component is abutted against the bottom of the second head part, and the other end of the elastic component is abutted against the inner wall of the low-pressure oil cavity; the side wall of the first head is provided with an oil inlet, the bottom of the second head, which is located in the low-pressure oil cavity, is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger.

Technical Field

The application particularly relates to a pressure limiting valve device, a pressure regulating plunger and a hydraulic pump.

Background

Pumps are machines that transport or pressurize fluid, and for example, in order to ensure the proper operation of engines and transmissions, oil pumps are required to provide a stable and reliable supply of lubricating oil under pressure.

In the prior art, a pressure limiting valve device is usually designed on an oil pump to maintain a constant oil pressure, and a pressure regulating plunger is designed on the pressure limiting valve device, and the position of the pressure regulating plunger can move in a plunger accommodating cavity along with different feedback pressures, so that the high-pressure oil cavity and the low-pressure oil cavity are communicated to different degrees, the output oil pressure is changed, and the output oil pressure of the oil pump is in a required range, so as to achieve the purpose of pressure regulation.

However, in order to achieve this effect, during design, a proper gap must exist between the pressure regulating plunger and the plunger accommodating chamber, which results in a situation that oil leaks into the pressure feedback chamber through the gap between the high-pressure oil chamber and the pressure feedback chamber inside the pump body, and the leaked high-pressure oil interferes with normal pressure feedback of the pressure feedback chamber.

Therefore, there is a need to improve the structure of the existing pressure limiting device, so that the pressure limiting device can not only meet the normal operation of the pump, but also prevent the high-pressure liquid from leaking.

Disclosure of Invention

The application provides a pressure limiting valve device, which solves the problem that in the prior art, high-pressure oil leaks and enters a pressure feedback cavity to influence the normal work of an oil pump. The application further provides a pressure regulating plunger and a hydraulic pump.

The application provides a pressure limiting valve device, includes: the pressure regulating plunger piston and the elastic component are arranged in the plunger piston accommodating cavity;

the pressure regulating plunger comprises a first head part, a second head part and a connecting part connected between the first head part and the second head part; the outer wall surfaces of the first head part and the second head part are respectively matched with the inner wall surface of the plunger accommodating cavity; the first head part separates a pressure feedback cavity and a high-pressure oil cavity which are arranged in the plunger accommodating cavity; the second head portion separates a high-pressure oil chamber and a low-pressure oil chamber provided in the plunger accommodating chamber; one end of the elastic component is abutted against the bottom of the second head part, and the other end of the elastic component is abutted against the inner wall of the low-pressure oil cavity;

the side wall of the first head is provided with an oil inlet, the bottom of the second head, which is positioned in the low-pressure oil cavity, is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger; the pressure feedback cavity is communicated with an oil pressure position needing to obtain oil pressure feedback.

Preferably, the elastic component and the pressure regulating plunger are arranged along the axial direction of the plunger accommodating cavity.

Preferably, the oil passage provided inside the pressure regulating plunger includes: the oil inlet oil duct and the oil outlet oil duct are communicated with each other; wherein the content of the first and second substances,

the oil inlet oil duct is arranged at the first head part along the radial direction of the plunger accommodating cavity and is communicated with the oil inlet;

the oil outlet passage is arranged at the position of the connecting part along the axial direction of the plunger accommodating cavity; and is communicated with the oil outlet.

Preferably, a side wall surface of the first head portion, which is close to the high-pressure oil chamber, abuts against an inner wall surface of the plunger accommodating chamber;

the side wall surface of the first head abutting against the inner wall surface of the plunger accommodating cavity at least comprises a pair of symmetrically arranged oil inlets, and each pair of oil inlets corresponds to one oil inlet duct.

Preferably, the side wall surface of the first head part is provided with an annular groove, and the symmetrically arranged oil inlets are arranged in the annular groove.

The present application further provides a pressure regulating plunger comprising a first head, a second head, and a connecting portion connected between the first head and the second head;

the side wall of the first head is provided with an oil inlet, the bottom of the second head is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger.

Preferably, the oil passage provided inside the pressure regulating plunger includes: the oil inlet oil duct and the oil outlet oil duct are communicated with each other; wherein the content of the first and second substances,

the oil inlet oil duct is arranged at the first head part along the radial direction of the first head part and is communicated with the oil inlet;

the oil outlet passage is arranged at the position of the connecting part along the axial direction of the connecting part; and is communicated with the oil outlet.

Preferably, the side wall surface of the first head part at least comprises a pair of symmetrically arranged oil inlets, and each pair of oil inlets corresponds to one oil inlet channel.

Preferably, the side wall surface of the first head part is provided with an annular groove, and the symmetrically arranged oil inlets are arranged in the annular groove. The present application further provides a hydraulic pump, including: the pump body, the plunger type pressure limiting device;

the pump body comprises an oil inlet cavity and an oil outlet cavity;

the plunger type pressure limiting device comprises a plunger containing cavity, and the plunger containing cavity comprises a low-pressure oil cavity, a high-pressure oil cavity and a pressure feedback cavity;

the oil inlet cavity is communicated with the low-pressure oil cavity; the oil outlet cavity is communicated with the high-pressure oil cavity and an oil outlet pipe arranged at the tail end of the pump body; the pressure feedback cavity is communicated with an oil pressure position which is arranged at the tail end of an oil way of the oil outlet pipe and obtains oil pressure feedback;

the plunger type pressure limiting device also comprises a pressure regulating plunger and an elastic component which are arranged in the plunger accommodating cavity;

the plunger type pressure limiting device comprises: the pressure regulating plunger and the elastic component are arranged in the plunger accommodating cavity; the pressure regulating plunger comprises a first head part, a second head part and a connecting part connected between the first head part and the second head part; the outer wall surfaces of the first head part and the second head part are respectively matched with the inner wall surface of the plunger accommodating cavity; the first head part separates a pressure feedback cavity and a high-pressure oil cavity which are arranged in the plunger accommodating cavity; the second head portion separates a high-pressure oil chamber and a low-pressure oil chamber provided in the plunger accommodating chamber; one end of the elastic component is abutted against the bottom of the second head part, and the other end of the elastic component is abutted against the inner wall of the low-pressure oil cavity; the side wall of the first head is provided with an oil inlet, the bottom of the second head, which is located in the low-pressure oil cavity, is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger.

Compared with the prior art, the method has the following advantages:

the application provides a pressure limiting valve device, includes: the pressure regulating plunger piston and the elastic component are arranged in the plunger piston accommodating cavity; the pressure regulating plunger comprises a first head part, a second head part and a connecting part connected between the first head part and the second head part; the outer wall surfaces of the first head part and the second head part are respectively matched with the inner wall surface of the plunger accommodating cavity; the first head part separates a pressure feedback cavity and a high-pressure oil cavity which are arranged in the plunger accommodating cavity; the second head portion separates a high-pressure oil chamber and a low-pressure oil chamber provided in the plunger accommodating chamber; one end of the elastic component is abutted against the bottom of the second head part, and the other end of the elastic component is abutted against the inner wall of the low-pressure oil cavity; the side wall of the first head is provided with an oil inlet, the bottom of the second head, which is positioned in the low-pressure oil cavity, is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger; the pressure feedback cavity is communicated with an oil pressure position needing to obtain oil pressure feedback. The pressure limiting valve device abandons the drawback that there must be suitable spaced between original pressure regulating plunger and the pump body, through the mode that sets up the oil duct that runs through the pressure regulating plunger, makes the fluid that flows into clearance between first head and the plunger holding chamber from the high pressure oil pocket, can flow back to the low pressure oil intracavity, has avoided the oil of high pressure oil pocket to reveal the pressure feedback chamber to the influence to the oil pressure control effect has been avoided.

Drawings

FIG. 1 is a schematic structural view of a pressure limiting valve assembly provided in accordance with a first embodiment of the present application;

fig. 2 is a schematic structural view of a pressure regulating plunger inside a pressure limiting valve device provided in the first embodiment of the present application.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and is therefore not limited to the specific embodiments disclosed below.

In the present application, a pressure limiting valve device and a pressure regulating plunger and a hydraulic pump are provided, respectively. Details are described in the following examples one by one.

First, the structure of the pressure limiting valve device according to the first embodiment of the present application will be described with reference to fig. 1 and 2.

As shown in fig. 1, which is a plunger type pressure limiting device according to a first embodiment of the present application, the plunger type pressure limiting device includes a plunger accommodating cavity 107 disposed in a machine body 101, and a pressure regulating plunger 102 and an elastic member 103 disposed inside the plunger accommodating cavity 107.

The plunger accommodating cavity 107 is divided into 3 areas, which are respectively: a low-pressure oil chamber 104, a high-pressure oil chamber 105, and a pressure feedback chamber 106.

In the first embodiment of the present application, the machine body 101 specifically refers to a housing providing an accommodating cavity and an oil path for the whole mechanism; the body 101 is the assembly base of the entire device.

The pressure limiting valve device provided by the embodiment can be used for a hydraulic pump in some scenes. The main function of the hydraulic pump is to pressurize the fluid to deliver the fluid (e.g., oil, lubricant), and the function of the pump is to provide a stable and appropriate delivery pressure for the delivered fluid. For example: in engines and transmissions, since a certain amount of lubricating oil is required for cooling friction pairs and gear pairs, the oil pump is required to provide a stable lubricating oil supply with a certain pressure. In order to meet such demands, it is necessary to be able to automatically adjust the pump-out oil pressure of the pump; the pressure limiting valve device provided by the embodiment helps to realize the function.

To achieve the above regulation function, the pressure feedback chamber 106 communicates with an oil pressure position where oil pressure feedback is required. Specifically, the oil pressure position where the oil pressure feedback is obtained obtains the oil pressure at the end of the oil passage.

In the first embodiment of the present application, the pressure feedback chamber 106 changes with the change of the pressure at the oil pressure position, and two ends of the elastic member 103 are respectively connected to the bottom of the pressure regulating plunger 102 and the inner wall of the plunger accommodating chamber 101. Since the pressure feedback chamber 106 has the same pressure as that generated by the oil pressure position, the pressure feedback chamber 106 can provide the pressure of the pressure regulating plunger 102 in the axial direction of the plunger accommodating chamber, and the pressure can reflect the pressure change of the oil pressure position. Under the condition that the pump normally works, namely, when the pressure of liquid at the outlet of the pump is in a preset stable state, the oil pressure born by each part of the pressure regulating plunger 102 and the elastic force provided by the elastic component 103 enable the pressure regulating plunger 102 to be in a balanced state in the plunger accommodating cavity 101, once the pressure at the outlet of the pump is increased, the preset stable state is changed, the pressure at the oil pressure position fed back by the oil pressure is also increased, the pressure at the oil pressure position fed back by the oil pressure acts on the pressure regulating plunger 102 through the pressure feedback cavity 106 until the balanced state of the pressure regulating plunger 102 in the plunger accommodating cavity 101 is broken, the position of the pressure regulating plunger 102 in the plunger accommodating cavity 101 is changed, the liquid in the high-pressure oil cavity 105 flows into the low-pressure oil cavity 104, the hydraulic pressure in the high-pressure oil cavity 105 is gradually reduced, and the hydraulic pressure at the outlet of the pump is gradually reduced, until the hydraulic pressure at the pump outlet is restored to a preset stable state.

Please refer to fig. 2, which is a schematic structural diagram of the pressure regulating plunger 102 disposed inside the plunger receiving cavity 107. The structure of the pressure limiting valve device proposed in the first embodiment of the present application will be described below with reference to fig. 1 and 2 in order to understand the operation of the device.

The pressure regulating plunger 102 includes a first head 1021, a second head 1022, and a connecting portion 1023 connected between the first head and the second head.

The pressure regulating plunger 102 functions to: 1. dividing the space inside the plunger housing chamber 101, thereby forming a low-pressure oil chamber 104, a high-pressure oil chamber 105, and a pressure feedback chamber 106; 2. the pressure of the high-pressure oil chamber 105 is changed by the movement within the plunger housing chamber 101.

In order to enable the pressure regulating plunger to achieve the above function, the outer wall surfaces of the first head part 1021 and the second head part 1022 are respectively matched with the inner wall surface of the plunger accommodating cavity 101; the specific fit is a clearance fit, a typical clearance size range is, for example, 0.03mm to 0.007 mm; in this way, the pressure regulating plunger can flexibly move along the plunger accommodating cavity 101, and the low-pressure oil cavity 104, the high-pressure oil cavity 105 and the pressure feedback cavity 106 can be isolated by the cooperation of the oil film.

The first head 1021 separates a pressure feedback chamber 106 and a high-pressure oil chamber 105 provided in the plunger housing chamber 101; the second head part 1022 separates the high-pressure oil chamber 105 and the low-pressure oil chamber 104 provided in the plunger housing chamber 101.

As shown in fig. 1, one end of the elastic member 103 abuts against the bottom of the second head part 1022, and the other end abuts against the inner wall of the low-pressure oil chamber 104, and the elastic member and the pressure-regulating plunger are arranged along the axial direction of the plunger accommodating chamber.

Under the condition that the pump normally works, the elastic component 103 is used for balancing the axial force applied to the pressure regulating plunger 102 by the high-pressure oil chamber 105 and the pressure feedback chamber 106, so that the pressure regulating plunger is in a balanced state in the plunger accommodating chamber 101.

An oil inlet 201 is formed in the side wall of the first head 1021, an oil outlet 202 is formed in the bottom of the low-pressure oil chamber of the second head 1022, and the oil inlet 201 is connected with the oil outlet 202 through an oil passage formed in the pressure regulating plunger 102.

As shown in fig. 2, the oil passage provided inside the pressure regulating plunger 102 includes: an oil inlet gallery 2031 and an oil outlet gallery 2032 that are communicated with each other.

The oil inlet duct 2031 is arranged at the first head 1021 along the radial direction of the plunger accommodating cavity 101, and is communicated with the oil inlet 201;

the oil outlet passage 2032 is arranged at the position of the connection portion 1023 in the axial direction of the plunger accommodating chamber 101; and is in communication with said oil outlet 202.

The oil passage, the oil inlet 201 and the oil outlet 202 jointly form a liquid channel inside the pressure regulating plunger 102.

In the first embodiment of the present application, the low-pressure oil chamber 104 communicates with an oil inlet chamber of the pump, and the high-pressure oil chamber 105 communicates with an oil outlet chamber of the pump. Before the pump is started, the oil inlet cavity of the pump is filled with conveyed liquid, and the liquid enters the oil outlet cavity through the energy conversion of the pump and then flows out through the oil passage communicated with the oil outlet cavity. Therefore, the hydraulic pressure in the high-pressure oil chamber 105 is greater than the hydraulic pressure in the low-pressure oil chamber 104, and since the pressure feedback chamber 106 is communicated with the end of the oil passage, a certain energy loss is inevitably generated when the liquid flows out through the oil passage, and therefore, the pressure in the pressure feedback chamber 106 is lower than the pressure in the high-pressure oil chamber 105 and higher than the pressure in the low-pressure oil chamber 104.

Since there is a pressure difference between the high-pressure oil chamber 105 and the pressure feedback chamber 106, and there is a gap between the first head 1021 and the inner wall surface of the plunger housing chamber 101, a small amount of leakage of the liquid present in the high-pressure oil chamber 105 may occur. However, the pressure inside the high-pressure oil chamber 105 or the pressure feedback chamber 106 is higher than that inside the low-pressure oil chamber 104, so the oil leaked from the high-pressure oil chamber 105 finally flows into the oil inlet 201 and flows back to the low-pressure oil chamber 104 through the oil passage provided inside the pressure regulating plunger 102. The first embodiment of the application fully considers the pressure difference of each area in the plunger accommodating cavity 101, and avoids the problem that the oil pressure control effect is influenced because the oil of the high-pressure oil cavity 105 leaks into the pressure feedback cavity 106 by the way of arranging the oil passage penetrating through the pressure regulating plunger 102.

In addition, in order to facilitate the oil inlet to collect leaked oil, an annular groove is further disposed on a side wall surface of the first head 1031, and the symmetrically disposed oil inlets 201 are disposed in the annular groove.

It should be noted that the design of the oil inlet and the oil inlet passage shown above is a preferred embodiment of the present device, and different structures can be adopted in other embodiments, for example: the oil inlet and the oil inlet channel can be designed to be multiple, namely, the side wall surface of the first head part abutting against the inner wall surface of the plunger accommodating cavity at least comprises a pair of symmetrically arranged oil inlets, and each pair of oil inlets corresponds to one oil inlet channel. In addition, each pair of oil inlets can be arranged on the same circumferential surface of the first head part at the same time, and can also be staggered mutually along the axial direction of the plunger piston accommodating cavity and arranged on the side wall surface of the first head part in sequence. These are simple variations of the structure of the plunger-type pressure-limiting device described in the first embodiment of the present application, without departing from the core of the present application, and are within the scope of protection of the present application.

In addition, the pressure limiting valve device provided by the first embodiment of the application can be applied to any hydraulic pump design to meet the requirement of the hydraulic pump on the pressure control of the hydraulic pump in specific application occasions, and can also be used as an independent unit for some hydraulic systems to meet the pressure stability control of the system.

In summary, the pressure limiting valve device provided in the first embodiment of the present application, structurally, overcomes the disadvantage that there must be a proper interval between the pressure regulating plunger and the pump body, and by setting the oil passage penetrating through the pressure regulating plunger, the oil flowing from the high pressure oil chamber into the gap between the first head and the plunger accommodating chamber can flow back into the low pressure oil chamber, thereby avoiding the oil in the high pressure oil chamber from leaking into the pressure feedback chamber, and avoiding the influence on the oil pressure control effect.

In the above embodiments, a pressure limiting valve device is provided, and accordingly, the second embodiment of the present application also provides a pressure regulating plunger, since the second embodiment is basically similar to the first embodiment, the description is simple, and the relevant points can be referred to the partial description of the first embodiment, and the pressure regulating plunger embodiments described below are only schematic.

A pressure regulating plunger provided in a second embodiment of the present application includes a first head portion, a second head portion, and a connecting portion connected between the first head portion and the second head portion;

the side wall of the first head is provided with an oil inlet, the bottom of the second head is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger.

Preferably, the oil passage provided inside the pressure regulating plunger includes: the oil inlet oil duct and the oil outlet oil duct are communicated with each other; the oil inlet channel is arranged at the first head part along the radial direction of the first head part and is communicated with the oil inlet; the oil outlet passage is arranged at the position of the connecting part along the axial direction of the connecting part; and is communicated with the oil outlet.

Preferably, the side wall surface of the first head part at least comprises a pair of symmetrically arranged oil inlets, and each pair of oil inlets corresponds to one oil inlet channel.

Preferably, the side wall surface of the first head part is provided with an annular groove, and the symmetrically arranged oil inlets are arranged in the annular groove.

The third embodiment of the present application further provides a hydraulic pump, which is substantially similar to the first embodiment, so that the description is simple, and the relevant points can be referred to the partial description of the first embodiment.

A third embodiment of the present application provides a hydraulic pump comprising: pump body, plunger type pressure limiting device.

The pump body comprises an oil inlet cavity and an oil outlet cavity;

the plunger type pressure limiting device comprises a plunger containing cavity, and the plunger containing cavity comprises a low-pressure oil cavity, a high-pressure oil cavity and a pressure feedback cavity;

the oil inlet cavity is communicated with the low-pressure oil cavity; the oil outlet cavity is communicated with the high-pressure oil cavity and an oil outlet pipe arranged at the tail end of the pump body; the pressure feedback cavity is communicated with an oil pressure position which is arranged at the tail end of an oil outlet pipe oil way and obtains oil pressure feedback.

The pump body is also usually provided with a gear for increasing the pressure of liquid, before the hydraulic pump is started, an oil inlet cavity in the pump body can be filled with the conveyed liquid, after the hydraulic pump is started, the liquid is driven by the gear to rotate at a high speed, the liquid is thrown to an oil outlet cavity from the oil inlet cavity, and the liquid obtains energy, flows out of an oil outlet pipe at a high pressure and enters a required place.

It should be noted that the internal structure and the operation principle of the hydraulic pump described in the third embodiment of the present application are not limited to the high-speed rotation of the liquid driven by the gear, and in other embodiments, different structures may be adopted inside the hydraulic pump, and naturally, different operation principles are also adopted, for example: a rotor can be further arranged in the pump body, and the rotor comprises an inner rotor and an outer rotor; the contour lines of the gears of the inner rotor and the outer rotor can always form point contact with each other, so that a plurality of working cavities can be formed between the inner rotor and the outer rotor, the volume of each working cavity can be changed along with the rotation of the rotor, if the working cavity communicated with the oil inlet cavity is enlarged, liquid can be sucked into the pump body, and correspondingly, if the working cavity communicated with the oil outlet cavity is reduced, the liquid can be pumped out. This also pertains to a simple modification of the internal structure of the pump body of the hydraulic pump according to the third embodiment of the present application, without departing from the core of the present application, and is within the scope of the present application.

In addition, the plunger type pressure limiting device also comprises a pressure regulating plunger and an elastic component which are arranged in the plunger containing cavity.

The pressure regulating plunger comprises a first head part, a second head part and a connecting part connected between the first head part and the second head part; the outer wall surfaces of the first head part and the second head part are respectively matched with the inner wall surface of the plunger accommodating cavity; the first head part separates a pressure feedback cavity and a high-pressure oil cavity which are arranged in the plunger accommodating cavity; the second head portion separates a high-pressure oil chamber and a low-pressure oil chamber provided in the plunger accommodating chamber; one end of the elastic component is abutted against the bottom of the second head part, and the other end of the elastic component is abutted against the inner wall of the low-pressure oil cavity;

the side wall of the first head is provided with an oil inlet, the bottom of the second head, which is located in the low-pressure oil cavity, is provided with an oil outlet, and the oil inlet is connected with the oil outlet through an oil duct arranged in the pressure regulating plunger.

Although the present application has been described with reference to the preferred embodiments, it is not intended to limit the present application, and those skilled in the art can make variations and modifications without departing from the spirit and scope of the present application, therefore, the scope of the present application should be determined by the claims that follow.