A compact micro axial piston pump

Abstract

This invention discloses a compact miniature axial plunger pump, belonging to the field of plunger pump technology. It includes a housing and a drive shaft, plunger, cylinder, and outlet base arranged sequentially within the housing. A limiting component is provided on the housing near the axial end of the cylinder close to the plunger. The limiting component is radially distributed along the cylinder, and its size is reduced according to the radius of the plunger's distribution circle. The rear end of the cylinder and the front end of the outlet base are axially connected by a locating pin. The outlet base is circumferentially fixed to the housing by fastening screws, achieving circumferential limiting. A nut is provided on the housing at the rear end of the outlet base, axially limiting the outlet base. This invention achieves miniaturization of the plunger pump, making it suitable for high-temperature and high-pressure downhole environments. By reducing the material in the limiting component and increasing the radius of the plunger's distribution circle, the power-to-weight ratio of the plunger pump is improved.

Description

Technical Field

[0001] This invention belongs to the field of plunger pump technology, and in particular relates to a compact micro axial plunger pump. Background Technology

[0002] A piston pump is an important component of a hydraulic system. It relies on the reciprocating motion of a piston within a cylinder to change the volume of the sealed working chamber, thereby achieving oil suction and pressure. Piston pumps offer advantages such as high rated pressure, compact structure, high efficiency, and convenient flow rate adjustment.

[0003] For downhole oil well applications, due to strict space constraints, plunger pumps need to be miniaturized to meet the requirements of narrow downhole tubing. However, ensuring the power-to-weight ratio of the miniaturized plunger pump and guaranteeing continuous and reliable operation under high temperature, high pressure, and vibration environments are pressing technical challenges that need to be addressed.

[0004] The specific technical issues are as follows:

[0005] 1. The main ways to improve the power-to-weight ratio of a miniature plunger pump are to increase the working pressure, increase the swashplate angle, increase the plunger distribution circle radius, and increase the working speed. However, due to limitations in materials and space, the increase in working pressure is limited. In addition, there are mutual constraints between the swashplate angle and the speed, as well as cavitation issues, so there are also upper limits to both the swashplate angle and the speed. Therefore, it is necessary to consider how to increase the plunger distribution circle radius within a limited space.

[0006] 2. One of the principles for ensuring high reliability of miniature plunger pumps is to minimize the number of mechanical parts to reduce the failure rate while ensuring the feasibility of the working principle. However, under high temperature, high pressure, and high speed conditions, the lifespan of the bearings in miniature plunger pumps is a bottleneck, and the main mechanism affecting bearing life is the load magnitude. Therefore, it is necessary to consider reducing the number of parts while simultaneously reducing the bearing load.

[0007] 3. Existing technologies for similar products mainly use pipe joints to achieve high-pressure fluid output. Installing and maintaining these joints in the harsh downhole environment is extremely cumbersome and unreliable. Therefore, an integrated connection method combining the miniature plunger pump and downhole tools needs to be considered.

[0008] 4. The pressure balance issue after the miniature plunger pump is installed needs to be considered.

[0009] To address the aforementioned problems, the inventors proposed a miniature axial piston pump that expands the piston distribution circle radius within a confined axial space by altering the discrete distribution of limiting components in the radial direction relative to the cylinder block. Simultaneously, to adapt to confined spaces, this miniature axial piston pump reduces the number of components and bearing loads, and its plug-in design facilitates easy assembly and disassembly with downhole workpieces. This ensures miniaturization of the piston pump while achieving high power density, meeting the requirements of use in confined downhole spaces and guaranteeing output reliability. Summary of the Invention

[0010] The purpose of this invention is to provide a miniature axial piston pump that expands the piston distribution circle radius within a confined axial space by altering the discrete distribution of limiting components in the radial direction of the cylinder block. Simultaneously, to adapt to confined spaces, this miniature axial piston pump reduces the number of components and bearing loads, and facilitates easy assembly and disassembly with downhole workpieces via a plug-in connection. This ensures miniaturization of the piston pump while achieving high power density, meeting the requirements of use in confined downhole spaces and guaranteeing output reliability.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A compact miniature axial piston pump includes a housing and a drive shaft, a swashplate, a piston, a cylinder, and an oil outlet base arranged sequentially within the housing.

[0013] The drive shaft and the swashplate are an integral structure, and the swashplate is provided with a waist-shaped groove at the position corresponding to the radius of the plunger distribution circle.

[0014] One end of the plunger engages with the swashplate, and the other end of the plunger engages with the front plunger bore of the cylinder to form a working chamber. The plunger has a hollow structure.

[0015] The housing is provided with a limiting component at one axial end of the cylinder body near the plunger. The limiting component is radially distributed along the cylinder body, and the size of the limiting component is reduced according to the radius of the distribution circle of the plunger.

[0016] The rear end of the cylinder and the front end of the oil outlet base are axially connected by a positioning pin. The oil outlet base is fixed to the outer shell in the circumferential direction by a fastening screw. The oil outlet base is circumferentially limited by the fastening screw. The outer shell is provided with a nut at the rear end of the oil outlet base. The oil outlet base is axially limited by the nut.

[0017] The end of the housing near the nut is a plug-in part, which is used to plug into and fix a downhole tool with a plug at the rear end;

[0018] The plunger hole of the cylinder body is connected to the oil outlet base. A distribution valve is provided between the cylinder body and the oil outlet base. When oil is sucked in, the oil enters the working chamber from the waist-shaped groove and the plunger in sequence. When oil is discharged, the oil enters the oil outlet base from the working chamber along the distribution valve and is discharged from the housing.

[0019] Furthermore, each plunger hole is provided with a corresponding distribution valve, and the oil outlet base is provided with a valve chamber for each distribution valve. One end of the distribution valve abuts against one end of the plunger hole outlet of the cylinder block, and the other end of the distribution valve extends into the valve chamber and is connected to the valve chamber through a first spring. The oil outlet base is provided with a radial oil outlet channel communicating with the bottom of the valve chamber. The radial oil outlet channel penetrates the oil outlet base, and the housing is provided with an oil outlet at the opening of the radial oil outlet channel.

[0020] Furthermore, the oil outlet base has an oil outlet hole at the center of its end face near the distribution valve, and the end of the oil outlet hole is connected to the radial oil outlet channel.

[0021] Furthermore, an oil inlet chamber is formed between the swash plate and the cylinder inside the housing, and an oil inlet is provided at the position of the oil inlet chamber on the housing. The end faces of the cylinder and the oil outlet base are respectively provided with positioning pin holes for cooperating with the positioning pin.

[0022] Furthermore, an oil inlet chamber is formed between the swash plate and the cylinder body inside the housing, and an oil inlet is provided at the position of the oil inlet chamber on the housing. The opposite end faces of the cylinder body and the oil outlet base are respectively provided with positioning pin holes for cooperating with the positioning pin. The cylinder body and the oil outlet base are provided with communicating oil passage holes along the axial direction. One end of the oil passage hole is connected to the oil inlet chamber, and the other end of the oil passage hole is connected to the sealed cavity.

[0023] Furthermore, the plunger is provided with a retaining ring and a second spring. The retaining ring is located at one end near the slipper, and the second spring is sleeved on the plunger and the plunger hole. One end of the second spring abuts against the cylinder body, and the other end of the second spring abuts against the retaining ring.

[0024] Furthermore, a first bearing and a second bearing are provided between the drive shaft and the housing. Both the first bearing and the second bearing are angular contact bearings. The first bearing is located near the swashplate. The inner ring of the drive shaft corresponding to the first bearing has a step. The inner ring of the drive shaft corresponding to the second bearing has a retaining ring. The outer ring portion between the first bearing and the second bearing has a support ring.

[0025] Furthermore, the end of the drive shaft away from the swashplate is connected to an external motor, and the housing is provided with a connector at one end of the drive shaft.

[0026] Furthermore, an inner sealing ring is provided between the outer periphery of the cylinder body and the oil outlet base and the housing. The housing is covered with three outer sealing rings. The first outer sealing ring is located at the position corresponding to the support ring of the housing, the second outer sealing ring is located at the position corresponding to the cylinder body of the housing, and the third outer sealing ring is located at the position corresponding to the oil outlet base of the housing.

[0027] The beneficial effects of this invention are:

[0028] 1) Without increasing the overall outer diameter of the micro plunger pump and without affecting the axial limit of the cylinder, the discrete distribution of the limit components in the radial direction of the cylinder is changed, and the limit components are reduced in material to expand the radius of the plunger distribution circle, thereby improving the power-to-weight ratio of the micro plunger pump, which is beneficial to the utilization of the micro plunger pump in narrow downhole spaces.

[0029] 2) By using a cartridge-type design and incorporating an oil passage for environmental pressure balancing, the efficiency of disassembling and assembling the plunger pump and downhole tools is improved. At the same time, it facilitates maintenance in harsh downhole environments and improves the reliability of use. The oil passage is set to balance the internal and external pressures.

[0030] 3) By setting a support ring between the outer rings of the two bearings and a retaining ring on the inner ring spindle, the axial force of the swashplate is distributed evenly, thereby reducing the bearing load, eliminating the need for a separate thrust bearing, simplifying the number of parts, and reducing the size and weight of the plunger pump. Attached Figure Description

[0031] Figure 1 This is a perspective view of a compact miniature axial piston pump according to the present invention.

[0032] Figure 2 This is a cross-sectional view of a compact micro axial piston pump according to the present invention.

[0033] Figure 3 for Figure 2 A cross-sectional view along the AA direction;

[0034] Figure 4 for Figure 2 Cross-sectional view along the BB direction;

[0035] Figure 5 for Figure 2 A cross-sectional view along the CC direction;

[0036] Figure 6 This is an exploded view of a compact miniature axial piston pump according to the present invention;

[0037] Figure 7 This is a schematic diagram of the swashplate and plunger assembly in this invention;

[0038] Figure 8 This is a perspective view of the swashplate in this invention;

[0039] Figure 9 This is a perspective view of the housing in this invention;

[0040] Figure 10 This is a cross-sectional view of the housing in this invention;

[0041] Figure 11 This is a perspective view of the cylinder block in this invention;

[0042] Figure 12 This is a rear view of the cylinder block in this invention, and a cross-sectional view in the DD and EE directions of the rear view;

[0043] Figure 13 This is a perspective view of the oil outlet base in the present invention from two directions;

[0044] Figure 14 This is a front view of the oil outlet base in this invention, and a cross-sectional view of the front view in the FF and GG directions.

[0045] In the diagram, 1-housing, 101-limiting assembly, 102-oil inlet, 103-oil outlet, 104-fastening screw, 2-drive shaft, 3-swashplate, 31-waisted groove, 4-plunger, 41-slipper, 42-retaining ring, 43-second spring, 5-cylinder body, 51-plunger hole, 6-oil outlet base, 61-valve chamber, 62-oil passage, 63-radial oil outlet channel, 64-oil outlet hole, 7-distribution valve, 71-first spring, 8-positioning pin, 81-positioning pin hole, 9-nut, 10-connector, 11-first bearing, 12-second bearing, 13-circlip, 14-support ring, 15-oil inlet chamber, 16-sealed chamber, 17-working chamber. Detailed Implementation

[0046] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] See Figures 1-14 The present invention provides a technical solution:

[0048] like Figures 1-2 As shown, a compact miniature axial piston pump includes a housing and a drive shaft, a swashplate, a piston, a cylinder, and an oil outlet base arranged sequentially within the housing.

[0049] The housing is a slender cylindrical structure, which meets the requirements of the narrow downhole tubing space. The end near the drive shaft is connected to the front motor, and the end near the oil outlet base is connected to the rear downhole tool.

[0050] like Figure 2 and Figure 3As shown, the drive shaft is fixed to one side of the horizontal end face of the swashplate, driving the swashplate to rotate synchronously. A waist-shaped groove is provided on one side of the swashplate corresponding to the radius of the plunger distribution circle. One end of the plunger engages with the swashplate's swashplate surface, and the other end engages with the plunger bore in the cylinder block to form a sealed working chamber, wherein the plunger is a hollow structure.

[0051] With the above technical solution, since the plunger and plunger hole seal to form a closed working cavity, when the swashplate rotates, the plunger moves in and out of the plunger hole, causing the volume of the working cavity to change. At the same time, the waist-shaped groove and the plunger form an alternating fit.

[0052] When the volume of the working chamber increases, the internal negative pressure draws oil from the exposed portion of the waist-shaped groove, and then into the working chamber along the hollow plunger, thus achieving the oil suction action. When the volume of the working chamber decreases, the oil is squeezed out from the rear end of the plunger hole into the oil outlet base, thus achieving the oil discharge action. In this embodiment, two sets of plungers are used, which, in conjunction with the swashplate, form an alternating circulating flow path.

[0053] Furthermore, such as Figure 2 , Figure 9 and Figure 10 As shown, a limiting component is provided at one axial end of the housing corresponding to the cylinder block near the plunger. The limiting components are distributed radially along the cylinder block. The size of the limiting components is reduced according to the distribution circle radius of the plunger. By reducing the width of the limiting components in the radial direction, the inner diameter of the limiting components can be increased, thereby increasing the distribution circle radius of the plunger.

[0054] At the same time, the limit component can not only... Figure 9 The internal structure can be an arc-shaped stepped structure, or it can employ radially arranged pins, keyways, or other structures. By radially dispersing the limiting components at the front end of the cylinder, the power-to-weight ratio of the micro plunger pump can be increased by expanding the radius of the plunger's distribution circle without other adjustments. This is beneficial for utilizing the micro plunger pump in confined downhole spaces. Preferably, such as... Figure 9 As shown, the limiting component consists of two sets of symmetrical arc-shaped step structures.

[0055] Furthermore, the front end of the cylinder block is axially limited by a limiting component, while the rear end of the cylinder block is connected to the oil outlet base by a locating pin, such as... Figure 2 As shown in the cross-sectional view, the oil outlet base is circumferentially fixed to the outer shell by fastening screws, which restrict the circumferential rotation of the oil outlet base. The cylinder body, which is axially connected to the oil outlet base by a locating pin, also restricts the circumferential rotation.

[0056] Continue as Figure 2 As shown, a nut is provided at the rear end of the oil outlet base. The nut is used to restrict the axial movement of the oil outlet base, and at the same time, the nut also serves as a connector to connect with the downhole workpiece at the rear end.

[0057] like Figure 2 and Figure 6 As shown, a connector is located at the front end of the housing, and the connector is threaded. One end of the connector is threaded to the housing, and the other end is connected to an external motor. The end of the housing near the nut is a plug-in part. The plunger pump is plugged into and fixed to the downhole tool with a plug at the rear end through the plug-in part. This eliminates the need for traditional pipe joints and improves assembly and disassembly efficiency. It also facilitates maintenance in the harsh downhole environment and enhances reliability.

[0058] Because of the plug-in fixing method, a sealed cavity is formed between the plunger pump and the downstream downhole tool. In oil well environments below 3000 meters, the optimal design for a micro hydraulic system is to be entirely immersed in the well fluid. This means that the entire micro hydraulic system, when not in operation, is subjected to well fluid pressure exceeding 30 MPa. A sealed cavity would adversely affect the pump itself. To ensure no resistance during insertion, an oil passage is provided axially along the cylinder body and the outlet base. One end of the oil passage connects to the inlet chamber, and the other end connects to the sealed cavity. The oil passage allows oil from the inlet chamber to be introduced into the sealed cavity, thereby achieving a pressure balance between the inside and outside of the pump.

[0059] Furthermore, such as Figure 2 and Figure 11 As shown, a sealing ring is provided on the outside of the oil passage hole on the side of the cylinder body corresponding to the oil outlet base. The sealing ring prevents oil passing through the oil passage hole from leaking out from the connection between the cylinder body and the oil outlet base.

[0060] Furthermore, such as Figures 2-5 , Figures 11-14 As shown, the cylinder block is connected to the oil outlet base at the position corresponding to the plunger hole. A distribution valve is provided between the cylinder block and the oil outlet base for oil discharge. Each plunger hole is equipped with a distribution valve, and the oil outlet base has a valve chamber for each distribution valve. One end of the distribution valve abuts against one end of the plunger hole outlet of the cylinder block, and the other end of the distribution valve extends into the valve chamber and is connected to the valve chamber through a first spring. The oil outlet base has a radial oil outlet channel that communicates with the bottom of the valve chamber and penetrates the oil outlet base. The housing is provided with an oil outlet at the opening of the radial oil outlet channel.

[0061] like Figures 13-14 As shown, the oil outlet base has an oil outlet hole at the center of its end face near the distribution valve, and the end of the oil outlet hole is connected to the radial oil outlet channel. Oil flowing out of the plunger orifice can enter the radial oil outlet channel through the oil outlet hole and exit the housing through the oil outlet port. By providing the oil outlet hole, the damping of the oil in the radial oil outlet channel can be reduced, allowing the oil to be discharged from both ends of the radial oil outlet channel.

[0062] With the above technical solution, when the volume of the working chamber decreases, the oil in the working chamber compresses the first spring of the distribution valve, and the distribution valve is pressed into the valve chamber. Since the valve chamber and the end of the oil outlet are provided with grooves, the oil will enter the oil outlet through the end groove of the valve chamber, and then enter the radial oil outlet channel through the oil outlet, and finally be discharged from the oil outlet on the housing.

[0063] Furthermore, such as Figure 2 , Figure 3 and Figure 4 As shown, an oil inlet chamber is formed between the swash plate and the cylinder block. The housing is provided with an oil inlet corresponding to the position of the oil inlet chamber. In this embodiment, the miniature plunger pump can be fully immersed in the working oil. The oil enters the oil inlet chamber through the oil inlet, and then the oil is sucked into the working chamber by the cooperation of the swash plate and the plunger. Then the high-pressure oil is discharged.

[0064] Furthermore, such as Figure 2 , Figure 3 , Figure 7 and Figure 8 As shown, a slipper is provided at one end of the plunger near the swashplate. The slipper is fitted over the front end of the plunger and does not affect the plunger's oil suction. At the same time, the diameter of the slipper is greater than the width of the waist-shaped groove, while the arc length of the waist-shaped groove is less than the arc length between the two plungers.

[0065] With the above technical solution, during the rotation of the swashplate, the waist-shaped groove rotates continuously along the pitch circle radius of the plunger, allowing oil to enter the plunger through the waist-shaped groove. Furthermore, the arc length of the waist-shaped groove is less than the arc length between the two plungers, preventing oil trapping and ensuring that the two sets of plungers can alternately complete oil suction.

[0066] Furthermore, such as Figure 6 and Figure 7 As shown, the plunger is equipped with a retaining ring and a spring. The retaining ring is located at the end near the slipper, and the spring is sleeved on the plunger and plunger bore. One end of the spring abuts against the cylinder body, and the other end of the spring abuts against the retaining ring. The spring force keeps the slipper pressed firmly against the swashplate.

[0067] Furthermore, such as Figure 2 and Figure 3 As shown, a first bearing and a second bearing are provided between the drive shaft and the housing. Both the first bearing and the second bearing are angular contact bearings, which support the drive shaft. By setting two sets of bearings, the drive shaft can be supported under high temperature, high pressure, and high speed conditions, while also simplifying the number of parts and reducing the size and weight of the plunger pump.

[0068] Specifically, the first bearing is located near the swashplate. A step is provided on the inner ring of the drive shaft corresponding to the first bearing. A retaining ring is provided on the drive shaft corresponding to the inner ring of the second bearing. A support ring is provided on the outer ring portion between the first and second bearings. The outer ring of the second bearing is abutted by a connector. The step and support ring restrict the axial movement of the first bearing, and the retaining ring, support ring, and connector restrict the axial movement of the second bearing.

[0069] Furthermore, Figure 3 As shown, an inner sealing ring is provided between the outer periphery of the cylinder body and the oil outlet base and the housing, wherein the inner sealing ring on the oil outlet base is located behind the oil outlet.

[0070] Furthermore, such as Figure 2 , Figure 3 and Figure 6 As shown in the figure, the outer casing is fitted with three outer sealing rings. The first outer sealing ring is located at the position corresponding to the support ring of the casing, the second outer sealing ring is located at the position corresponding to the cylinder block, and the third outer sealing ring is located at the position corresponding to the oil outlet base. The oil inlet is located between the first and second outer sealing rings, and the oil outlet is located between the second and third outer sealing rings.

[0071] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A compact miniature axial piston pump, characterized in that: It includes a housing and a drive shaft, a swashplate, a plunger, a cylinder block, and an oil outlet base arranged sequentially within the housing; The drive shaft and the swashplate are an integral structure, and the swashplate is provided with a waist-shaped groove at the position corresponding to the radius of the plunger distribution circle. One end of the plunger engages with the swashplate, and the other end of the plunger engages with the front plunger bore of the cylinder to form a working chamber. The plunger has a hollow structure. The housing is provided with a limiting component at one axial end of the cylinder body near the plunger. The limiting component is radially distributed along the cylinder body, and the size of the limiting component is reduced according to the radius of the distribution circle of the plunger. The rear end of the cylinder and the front end of the oil outlet base are axially connected by a positioning pin. The oil outlet base is fixed to the outer shell in the circumferential direction by a fastening screw. The oil outlet base is circumferentially limited by the fastening screw. The outer shell is provided with a nut at the rear end of the oil outlet base. The oil outlet base is axially limited by the nut. The end of the housing near the nut is a plug-in part, which is used to plug into and fix a downhole tool with a plug at the rear end; The plunger hole of the cylinder body is connected to the oil outlet base. A distribution valve is provided between the cylinder body and the oil outlet base. When oil is sucked in, the oil enters the working chamber sequentially from the waist-shaped groove and the plunger. When oil is discharged, the oil enters the oil outlet base from the working chamber along the distribution valve and is discharged from the housing. After insertion, a sealed cavity is formed between the nut and the downhole tool. The cylinder and the oil outlet base are provided with a connecting oil passage hole in the axial direction. One end of the oil passage hole is connected to the oil inlet cavity, and the other end of the oil passage hole is connected to the sealed cavity. A slipper is fitted on one end of the plunger near the swashplate. A retaining ring and a second spring are provided on the plunger. The retaining ring is located at the end near the slipper. The second spring is fitted on the plunger and the plunger bore. One end of the second spring abuts against the cylinder body, and the other end of the second spring abuts against the retaining ring.

2. The compact miniature axial piston pump according to claim 1, characterized in that: Each plunger hole is provided with a corresponding distribution valve, and the oil outlet base is provided with a valve chamber for each distribution valve. One end of the distribution valve abuts against one end of the plunger hole outlet of the cylinder block, and the other end of the distribution valve extends into the valve chamber and is connected to the valve chamber through a first spring. The oil outlet base is provided with a radial oil outlet channel communicating with the bottom of the valve chamber. The radial oil outlet channel passes through the oil outlet base, and the housing is provided with an oil outlet at the opening of the radial oil outlet channel.

3. The compact miniature axial piston pump according to claim 2, characterized in that: The oil outlet base has an oil outlet hole at the center of the end face near the distribution valve, and the end of the oil outlet hole is connected to the radial oil outlet channel.

4. The compact miniature axial piston pump according to claim 1, characterized in that: An oil inlet chamber is formed between the swash plate and the cylinder inside the housing. An oil inlet is provided at the position of the oil inlet chamber on the housing. The end faces of the cylinder and the oil outlet base are respectively provided with positioning pin holes for cooperating with the positioning pin.

5. The compact miniature axial piston pump according to claim 1, characterized in that: A first bearing and a second bearing are provided between the drive shaft and the housing. Both the first bearing and the second bearing are angular contact bearings. The first bearing is located near the swashplate. The inner ring of the drive shaft corresponding to the first bearing has a step. The inner ring of the drive shaft corresponding to the second bearing has a retaining ring. The outer ring portion between the first bearing and the second bearing has a support ring.

6. The compact miniature axial piston pump according to claim 1, characterized in that: The end of the drive shaft away from the swashplate is connected to an external motor, and the housing is provided with a connector at one end of the drive shaft.

7. The compact miniature axial piston pump according to claim 1, characterized in that: The cylinder body and the oil outlet base are provided with inner sealing rings between their outer peripheries and the housing. The housing is covered with three outer sealing rings. The first outer sealing ring is located at the position of the housing corresponding to the support ring, the second outer sealing ring is located at the position of the housing corresponding to the cylinder body, and the third outer sealing ring is located at the position of the housing corresponding to the oil outlet base.

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