Miniature axial plunger pump with compact structure

Abstract

The invention discloses a miniature axial plunger pump with a compact structure, which belongs to the technical field of plunger pumps and comprises a shell, a transmission shaft, a plunger, a cylinder body and an oil outlet base, limiting assemblies are arranged at the axial end, corresponding to the cylinder body and close to the plunger, of the shell, the limiting assemblies are discretely distributed in the radial direction of the cylinder body, and the size of the limiting assemblies is subjected to corresponding material reduction treatment according to the distribution circle radius of the plunger. The rear end of the cylinder body is axially connected with the front end of the oil outlet base through a positioning pin, the oil outlet base is fixed to the shell through a fastening screw in the circumferential direction, the oil outlet base completes circumferential limiting through the fastening screw, and a nut is arranged at the position, located at the rear end of the oil outlet base, of the shell. And the oil outlet base is axially limited through the nut. Miniaturization of the plunger pump is achieved, the plunger pump is suitable for the underground high-temperature and high-pressure environment, and the power-to-weight ratio of the plunger pump is increased by reducing materials of the limiting assembly and enlarging the distribution circle radius of the plunger.

Description

Technical Field

[0001] The invention belongs to the technical field of plunger pumps, and in particular relates to a miniature axial plunger pump with a compact structure. Background Art

[0002] The plunger pump is a key component in hydraulic systems. It relies on the reciprocating motion of the plunger within the cylinder, causing the volume of the sealed working chamber to change to achieve oil suction and pressure. Plunger pumps offer advantages such as high rated pressure, compact structure, high efficiency, and easy flow regulation.

[0003] For oil well applications, due to strict space constraints, miniaturization of plunger pumps is necessary to meet the requirements of the narrow pipe string space. However, how to maintain the power-to-weight ratio of the miniaturized plunger pump and how to ensure continuous and reliable operation in high temperature, high pressure, and vibration environments are technical difficulties that need to be solved urgently.

[0004] The specific technical issues are as follows: 1. The main approaches to improving the power-to-weight ratio of a micro plunger pump include increasing the operating pressure, increasing the swash plate angle, increasing the plunger distribution circle radius, and increasing the operating speed. However, due to material and space constraints, the operating pressure increase is limited. Furthermore, the swash plate angle and speed are mutually restricted, as well as cavitation issues, so there are upper limits to the swash plate angle and speed. Therefore, it is necessary to consider how to increase the plunger distribution circle radius within the confined space.

[0005] 2. One of the principles for ensuring high reliability of micro plunger pumps is to minimize mechanical components to reduce failure rates while ensuring the working principle is feasible. However, under high temperature, high pressure, and high speed conditions, the life of micro plunger pump bearings is a bottleneck. The main mechanism affecting bearing life is load. Therefore, it is necessary to consider reducing the number of components and bearing load at the same time.

[0006] 3. Existing similar products primarily use pipe joints to achieve high-pressure fluid output. These joints are extremely cumbersome to install and maintain in the harsh downhole environment, and their reliability is low. Therefore, an integrated connection method for the micro plunger pump and downhole tools is needed.

[0007] 4. The pressure balance problem after the micro plunger pump is installed needs to be considered.

[0008] To address these issues, the inventors have proposed a miniature axial piston pump that expands the radius of the piston distribution circle within a confined axial space by varying the discrete distribution of the stopper assembly in the radial direction relative to the cylinder body. This miniature axial piston pump also reduces component count and bearing loads to accommodate the confined space, while also facilitating assembly and disassembly with downhole workpieces through a plug-in connection. This ensures both miniaturization and high power density, meeting the requirements of downhole use while guaranteeing output reliability. Summary of the Invention

[0009] The present invention aims to provide a miniature axial piston pump that expands the radius of the piston distribution circle by varying the discrete distribution of the stopper assembly in the radial direction relative to the cylinder body within a narrow axial space. Furthermore, the miniature axial piston pump reduces component count and bearing loads to accommodate the confined space, and facilitates assembly and disassembly with downhole workpieces through plug-in connection. This ensures miniaturization while achieving high power density, meeting the requirements for use in confined downhole spaces and guaranteeing output reliability.

[0010] The object of the present invention is achieved through the following technical solutions: A compact micro axial piston pump comprises a housing and a transmission shaft, a swash plate, a plunger, a cylinder body and an oil outlet base arranged in sequence in the housing; The transmission shaft and the swash plate are an integrated structure, and the swash plate is provided with a waist-shaped groove at a position corresponding to the radius of the plunger distribution circle; One end of the plunger cooperates with the swash plate, and the other end of the plunger cooperates with the front plunger hole of the cylinder body to form a working chamber, and the plunger is a hollow structure; The housing is provided with a limit assembly at one axial end of the cylinder body close to the plunger. The limit assembly is discretely distributed along the radial direction of the cylinder body, and the size of the limit assembly is reduced according to the distribution circle radius of the plunger; The rear end of the cylinder body and the front end of the oil outlet base are axially connected by a positioning pin, and the oil outlet base is fixed to the housing in the circumferential direction by a fastening screw. The oil outlet base is circumferentially limited by the fastening screw. The housing is provided with a nut at the rear end of the oil outlet base, and the oil outlet base is axially limited by the nut. One end of the housing close to the nut is a plug-in portion, which is used to be plugged and fixed to a downhole tool with a plug at the rear end; The plunger hole of the cylinder body is connected to the oil outlet base, and a distribution valve is provided between the cylinder body and the oil outlet base. When absorbing oil, the oil enters the working chamber from the waist-shaped groove and the plunger in sequence; when discharging oil, the oil enters the oil outlet base from the working chamber along the distribution valve and is discharged from the shell.

[0011] Furthermore, a distribution valve is provided corresponding to each plunger hole, and a valve cavity is provided corresponding to each distribution valve in the oil outlet base. One end of the distribution valve abuts against one end of the plunger hole outlet of the cylinder body, and the other end of the distribution valve extends into the valve cavity and is connected to the valve cavity through a first spring. The oil outlet base is provided with a radial oil outlet channel connected to the bottom of the valve cavity, and the radial oil outlet channel passes through the oil outlet base, and the shell is provided with an oil outlet at the opening of the radial oil outlet channel.

[0012] Furthermore, the oil outlet base is provided with an oil outlet hole at the center of the end face close to the distribution valve, and the end of the oil outlet hole is connected to the radial oil outlet channel. Furthermore, an oil inlet cavity is formed between the corresponding swash plate and the cylinder body in the housing, an oil inlet is provided at the position of the housing corresponding to the oil inlet cavity, and 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.

[0013] Furthermore, an oil inlet chamber is formed between the corresponding swash plate and the cylinder body in the housing, an oil inlet port is provided at a position corresponding to the oil inlet chamber, and the opposite end surfaces of the cylinder body and the oil outlet base are respectively provided with positioning pin holes for cooperating with the positioning pin, and the cylinder body and the oil outlet base are provided with a communicating oil through hole along the axial direction, one end of the oil through hole is communicated with the oil inlet chamber, and the other end of the oil through hole is communicated with the closed chamber.

[0014] Furthermore, a retaining ring and a second spring are provided on the plunger, the retaining ring is located at one end close to the sliding shoe, the second spring is sleeved outside 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.

[0015] Furthermore, a first bearing and a second bearing are provided between the transmission shaft and the housing. The first bearing and the second bearing both adopt angular contact bearings. The first bearing is close to the side of the swash plate. The transmission shaft is provided with a step corresponding to the inner ring of the first bearing, and the transmission shaft is provided with a retaining spring at the inner ring position corresponding to the second bearing. A support ring is provided on the outer ring part between the first bearing and the second bearing.

[0016] Furthermore, one end of the transmission shaft away from the swash plate is connected to an external motor, and the housing is provided with a connector at one end of the transmission shaft.

[0017] Furthermore, an inner sealing ring is provided between the outer periphery of the cylinder body and the oil outlet base and the shell, and three outer sealing rings are provided on the outer shell of the shell, the first outer sealing ring is located at the position of the shell corresponding to the support ring, the second outer sealing ring is located at the position of the shell corresponding to the cylinder body, and the third outer sealing ring is located at the position of the shell corresponding to the oil outlet base.

[0018] The beneficial effects of the present invention are: 1) Without increasing the overall outer diameter of the micro plunger pump and affecting the axial limit of the cylinder, the discrete distribution of the limit assembly in the radial direction of the cylinder is changed, and the limit assembly is 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 conducive to the utilization of the micro plunger pump in a narrow underground space.

[0019] 2) The plug-in method and the built-in oil hole for environmental pressure balance improve the efficiency of disassembly and assembly of the plunger pump and downhole tools, facilitate maintenance in harsh downhole environments, improve reliability, and balance internal and external pressures by setting the oil hole.

[0020] 3) By providing a support ring between the two bearing outer rings and a retaining spring on the inner ring main shaft, the axial force of the swash plate is evenly distributed to reduce the bearing load, eliminate the need for a separate thrust bearing, simplify the number of parts, and reduce the volume and weight of the plunger pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A three-dimensional diagram of a compact micro axial piston pump according to the present invention; Figure 2 A cross-sectional view of a compact micro axial piston pump according to the present invention; Figure 3 for Figure 2 Cross-sectional view in the AA direction; Figure 4 for Figure 2 Cross-sectional view in the middle BB direction; Figure 5 for Figure 2 Cross-sectional view in CC direction; Figure 6 An exploded view of a compact micro axial piston pump according to the present invention; Figure 7 Schematic diagram of the cooperation between the swash plate and the plunger in the present invention; Figure 8 is a perspective view of the swash plate of the present invention; Figure 9 is a three-dimensional diagram of the housing in the present invention; Figure 10 is a cross-sectional view of the housing in the present invention; Figure 11 It is a three-dimensional diagram of the cylinder body of the present invention; Figure 12 It is a rear view of the cylinder body of the present invention, and a cross-sectional view in the DD direction and the EE direction of the rear view; Figure 13 The three-dimensional diagram of the oil outlet base in the present invention in two directions; Figure 14 It is a front view of the oil outlet base of the present invention, and a cross-sectional view in the FF direction and the GG direction of the front view; In the figure, 1-housing, 101-limiting assembly, 102-oil inlet, 103-oil outlet, 104-fastening screw, 2-drive shaft, 3-swash plate, 31-waist groove, 4-plunger, 41-slipper, 42-blocking ring, 43-second spring, 5-cylinder body, 51-plunger hole, 6-oil outlet base, 61-valve chamber, 62-oil through hole, 63-radial oil outlet channel, 64-oil outlet hole, 7-distribution valve, 71-first spring, 8-locating pin, 81-locating 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 DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0023] See Figures 1-14 , the present invention provides a technical solution: like Figure 1-Figure 2 As shown, a compact micro axial piston pump includes a housing and a transmission shaft, a swash plate, a plunger, a cylinder body and an oil outlet base arranged in sequence in the housing.

[0024] The housing is a slender cylindrical structure that meets the requirements of the narrow pipe string space downhole. The end near the drive shaft is connected to the front motor, and the end near the oil outlet base is connected to the back downhole tool.

[0025] like Figure 2 and Figure 3 As shown, the drive shaft is integrally fixed to one side of the horizontal end face of the swash plate, driving the swash plate in synchronous rotation. A waist-shaped groove is located on the slanted surface of the swash plate, corresponding to the radius of the plunger distribution circle. One end of the plunger engages the slanted surface of the swash plate, while the other end engages the plunger hole in the cylinder block, forming a sealed working chamber. The plunger is a hollow structure.

[0026] Through the above technical solution, since the plunger and the plunger hole are sealed to form a closed working chamber, when the swash plate rotates, the plunger performs telescopic movement in the plunger hole, causing the volume of the working chamber to change, and at the same time, the waist-shaped groove and the plunger form an alternating fit.

[0027] When the working chamber volume increases, the internal negative pressure draws oil through the exposed portion of the waist-shaped groove and then into the working chamber along the hollow plunger, achieving oil suction. When the working chamber volume decreases, the oil is squeezed out of the rear end of the plunger hole into the oil outlet base, achieving oil discharge. In this embodiment, two sets of plungers are used, and these two sets of plungers cooperate with the swash plate to form an alternating circulation flow path.

[0028] Further, if Figure 2 、 Figure 9 and Figure 10 As shown, a limit assembly is provided at the axial end of the shell corresponding to the cylinder body close to the plunger. The limit assembly is discretely distributed along the radial direction of the cylinder body. The size of the limit assembly is reduced according to the distribution circle radius of the plunger. By reducing the width of the limit assembly in the radial direction, the inner diameter of the limit assembly can be expanded, thereby expanding the distribution circle radius of the plunger.

[0029] At the same time, the limit component can not only Figure 9 The arc-shaped step structure in the shell can also be used with radially arranged pins, keyways and other structures. By arranging the limit assembly radially and discretely at the front end of the cylinder, the power-to-weight ratio of the micro-plunger pump can be improved by expanding the radius of the distribution circle of the plunger without making other adjustments to the micro-plunger pump, which is conducive to the utilization of the micro-plunger pump in a narrow underground space. Figure 9 As shown, the limiting assembly is two sets of arc-shaped step structures that are symmetrical in the upper and lower directions.

[0030] Furthermore, the front end of the cylinder body is axially limited by a limiting assembly, and the rear end of the cylinder body is connected to the oil outlet base through a positioning pin, such as Figure 2 As shown in the cross-sectional view, the oil outlet base is fixed to the housing in the circumferential direction by fastening screws, and the circumferential rotation of the oil outlet base is limited by the fastening screws, and the cylinder body axially connected to the oil outlet base by the locating pin also limits the circumferential rotation.

[0031] Continue as Figure 2 As shown, a nut is provided at the rear end of the oil outlet base, and the nut is used to limit the axial movement of the oil outlet base. At the same time, the nut also serves as a plug-in portion to be plugged into the downhole workpiece at the rear end.

[0032] like Figure 2 and Figure 6 As shown, the front end of the housing is equipped with a connector with threads. One end of the connector is connected to the housing via threads, and the other end is connected to an external motor. The end of the housing near the nut is a plug-in connector, which connects the plunger pump to the downhole tool with a plug at the rear end. This connector eliminates the need for traditional pipe joints. This plug-in connector improves assembly and disassembly efficiency, facilitates maintenance in the harsh underground environment, and improves reliability.

[0033] Due to the plug-in mounting method, a sealed cavity is formed between the plunger pump and the back-end downhole tool. In oil wells below 3,000 meters, the ideal design for a micro-hydraulic system is to immerse the entire system in well fluid. This means that the entire micro-hydraulic system is subject to well fluid pressure exceeding 30 MPa when not in operation. This sealed cavity would adversely affect the pump itself. To ensure resistance during insertion, an oil hole is axially connected between the cylinder body and the oil outlet base. One end of the oil hole connects to the oil inlet cavity, and the other end connects to the sealed cavity. The oil hole directs oil from the oil inlet cavity into the sealed cavity, thereby achieving a state of pressure equilibrium between the internal and external pressures of the pump.

[0034] Further, if Figure 2 and Figure 11 As shown, a sealing ring is provided on the outside of the oil through hole on the side of the cylinder body corresponding to the oil outlet base, so as to prevent the oil passing through the oil through hole from leaking from the connection between the cylinder body and the oil outlet base.

[0035] Further, if Figure 2-Figure 5 、 Figure 11-14 As shown, the position of the cylinder body corresponding to the plunger hole is connected to the oil outlet base, and a distribution valve is installed between the cylinder body and the oil outlet base for draining oil. Each plunger hole is provided with a distribution valve, and the oil outlet base has a valve cavity corresponding to each distribution valve. One end of the distribution valve abuts the outlet end of the plunger hole in the cylinder body, and the other end of the distribution valve extends into the valve cavity and is connected to the valve cavity via a first spring. The oil outlet base is provided with a radial oil outlet channel connected to the bottom of the valve cavity. The radial oil outlet channel runs through the oil outlet base, and the housing is provided with an oil outlet at the opening corresponding to the radial oil outlet channel.

[0036] like Figure 13-14 As shown, the oil outlet base has an oil outlet hole located near the center of the end face of the distribution valve. The distal end of the oil outlet hole communicates with the radial oil outlet channel. Oil flowing out of the plunger bore can enter the radial oil outlet channel through the oil outlet hole and exit the housing through the oil outlet port. The provision of the oil outlet hole reduces damping of the oil in the radial oil outlet channel, allowing oil to be discharged from both ends of the radial oil outlet channel.

[0037] Through the above technical solution, when the volume of the working chamber becomes smaller, 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 hole are provided with grooves, the oil will enter the oil outlet hole through the end groove of the valve chamber, and then enter the radial oil outlet channel through the oil outlet hole, and finally be discharged from the oil outlet port on the housing.

[0038] Further, if Figure 2 、 Figure 3 and Figure 4As shown, an oil inlet chamber is formed between the swash plate and the cylinder body, and an oil inlet port is provided at a position of the housing corresponding to the oil inlet chamber. The micro plunger pump of this embodiment can be fully immersed in the working oil. The oil enters the oil inlet chamber through the oil inlet port, and then the oil is sucked into the working chamber through the cooperation of the swash plate and the plunger, and then the high-pressure oil is discharged.

[0039] Further, if Figure 2 、 Figure 3 、 Figure 7 and Figure 8 As shown, a sliding shoe is provided at one end of the plunger close to the swash plate. The sliding shoe is sleeved on the front end of the plunger and does not affect the oil suction of the plunger. At the same time, the diameter of the sliding shoe is larger than the width of the waist-shaped groove, and the arc length of the waist-shaped groove is smaller than the arc length between the two plungers.

[0040] With this technical solution, as the swash plate rotates, the waist-shaped grooves rotate continuously along the plunger's pitch circle radius, allowing oil to enter the plunger through the waist-shaped grooves. The arc length of the waist-shaped grooves is shorter than the arc length between the two plungers, preventing oil trapping and ensuring that the two sets of plungers can alternately complete oil absorption.

[0041] Further, if Figure 6 and Figure 7 As shown, the plunger is equipped with a retaining ring and a spring. The retaining ring is located at one end near the sliding shoe. The spring is mounted outside the plunger and the plunger hole. One end of the spring abuts the cylinder body, and the other end of the spring abuts the retaining ring. The elastic force of the spring presses the sliding shoe against the swash plate.

[0042] Further, if 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 and second bearings are angular contact bearings, supporting the drive shaft. The two sets of bearings ensure support for the drive shaft 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.

[0043] Specifically, the first bearing is located near the swash plate. A step is provided on the inner ring of the transmission shaft corresponding to the first bearing. A retaining spring is provided on the inner ring of the second bearing. A support ring is provided on the outer ring between the first and second bearings. The outer ring of the second bearing is abutted by a connector. The step and support ring limit axial movement of the first bearing, while the retaining spring, support ring, and connector limit axial movement of the second bearing.

[0044] Further, Figure 3 As shown, inner sealing rings are 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.

[0045] Further, if Figure 2 、 Figure 3 and Figure 6 As shown in the figure, the housing is fitted with three outer sealing rings. The first outer sealing ring is located on the housing corresponding to the support ring, the second outer sealing ring is located on the housing corresponding to the cylinder block, and the third outer sealing ring is located on the housing 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.

[0046] The foregoing description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention can be used in various other combinations, modifications, and environments and can be modified within the scope of the concept described herein through the above teachings or techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A compact micro axial piston pump, characterized by: It includes a housing and a transmission shaft, a swash plate, a plunger, a cylinder body and an oil outlet base arranged in sequence in the housing; The transmission shaft and the swash plate are an integrated structure, and the swash plate is provided with a waist-shaped groove at a position corresponding to the radius of the plunger distribution circle; One end of the plunger cooperates with the swash plate, and the other end of the plunger cooperates with the front plunger hole of the cylinder body to form a working chamber, and the plunger is a hollow structure; The housing is provided with a limit assembly at one axial end of the cylinder body close to the plunger. The limit assembly is discretely distributed along the radial direction of the cylinder body, and the size of the limit assembly is reduced according to the distribution circle radius of the plunger; The rear end of the cylinder body and the front end of the oil outlet base are axially connected by a positioning pin, and the oil outlet base is fixed to the housing in the circumferential direction by a fastening screw. The oil outlet base is circumferentially limited by the fastening screw. The housing is provided with a nut at the rear end of the oil outlet base, and the oil outlet base is axially limited by the nut. One end of the housing close to the nut is a plug-in portion, which is used to be plugged and fixed to a downhole tool with a plug at the rear end; The plunger hole of the cylinder body is connected to the oil outlet base, and a distribution valve is provided between the cylinder body and the oil outlet base. When absorbing oil, the oil enters the working chamber from the waist-shaped groove and the plunger in sequence; when discharging oil, the oil enters the oil outlet base from the working chamber along the distribution valve and is discharged from the shell.

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

3. The compact micro axial piston pump according to claim 2, characterized in that: The oil outlet base is provided with an oil outlet hole at the center of the end surface close to the distribution valve, and the end of the oil outlet hole is communicated with the radial oil outlet channel.

4. The compact micro axial piston pump according to claim 1, characterized in that: An oil inlet cavity is formed between the corresponding swash plate and the cylinder body in the housing, and an oil inlet is provided at a position corresponding to the oil inlet cavity of the housing. The opposite end surfaces of the cylinder body and the oil outlet base are respectively provided with positioning pin holes for cooperating with the positioning pin.

5. The compact micro axial piston pump according to claim 1, characterized in that: A closed cavity is formed between the plugged nut and the downhole tool. The cylinder body and the oil outlet base are provided with a communicating oil hole in the axial direction. One end of the oil hole is connected to the oil inlet cavity, and the other end of the oil hole is connected to the closed cavity.

6. The compact micro axial piston pump according to claim 1, characterized in that: A sliding shoe is provided on the end of the plunger close to the swash plate, and a retaining ring and a second spring are provided on the plunger. The retaining ring is located at the end close to the sliding shoe, and the second spring is sleeved outside 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.

7. The compact micro axial piston pump according to claim 1, characterized in that: A first bearing and a second bearing are provided between the transmission shaft and the housing. Both the first bearing and the second bearing are angular contact bearings. The first bearing is close to the swash plate. A step is provided on the inner ring of the transmission shaft corresponding to the first bearing. A retaining spring is provided on the inner ring position of the transmission shaft corresponding to the second bearing. A support ring is provided on the outer ring portion between the first bearing and the second bearing.

8. The compact micro axial piston pump according to claim 1, characterized in that: One end of the transmission shaft away from the swash plate is connected to an external motor, and the housing is provided with a connector at one end of the transmission shaft.

9. The compact micro axial piston pump according to claim 1, characterized in that: An inner sealing ring is provided between the outer periphery of the cylinder body and the oil outlet base and the shell, and three outer sealing rings are provided on the outer shell of the shell. The first outer sealing ring is located at the position of the shell corresponding to the support ring, the second outer sealing ring is located at the position of the shell corresponding to the cylinder body, and the third outer sealing ring is located at the position of the shell corresponding to the oil outlet base.

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