Digital flow distribution and speed regulation type low-speed axial plunger pump

Abstract

This invention discloses a digital flow distribution and speed regulation low-speed axial piston pump, relating to the field of hydraulic pump technology. It includes a pump body, input shaft, swashplate, axial piston, spring, through shaft, encoder, and controller. When the pump enters the working state, the input shaft drives the swashplate to rotate. The rotation of the swashplate causes the slipper to oscillate and move axially, thereby causing the axial piston to reciprocate axially. During the axial movement of the axial piston, the change in volume within the piston cavity (excluding the piston itself) coordinates with the opening and closing of a two-position two-way solenoid valve to complete oil suction and discharge. The controller measures and calculates the angle and angular velocity of the input shaft based on signals from the encoder, determining the timing for opening and closing the two-position two-way solenoid valve. This invention's digital flow distribution and speed regulation low-speed axial piston pump can improve the volumetric efficiency and lifespan of the axial piston pump, enhance the heat dissipation of internal components, and make the pump body structure more compact.

Description

Technical Field

[0001] This invention relates to the field of hydraulic pump technology, and in particular to a digital flow distribution and speed regulation type low-speed axial piston pump. Background Technology

[0002] In recent years, hydraulic power generation technology has been applied to new energy power generation fields such as wind power and ocean energy. Traditional hydraulic power generation structures use a "fixed displacement hydraulic pump - variable displacement hydraulic motor" circuit to harvest wind or ocean energy. The hydraulic pump is generally a fixed displacement hydraulic pump designed based on a constant high speed drive principle. When operating under random low-speed input conditions such as wind power generation and ocean energy generation, these high-speed fixed displacement hydraulic pumps find it difficult to maintain their high performance, adaptability, long lifespan, and ease of maintenance.

[0003] Axial piston hydraulic pumps are compact in structure and have high volumetric efficiency at high speeds, making them one of the most commonly used hydraulic pumps. Each piston reciprocates once for every revolution of the input spindle. To accurately perform oil suction and discharge operations, either a distribution plate or valve distribution technology is typically employed. In a distribution plate structure, the piston assembly rotates with the input shaft, while the swashplate and distribution plate remain stationary. The displacement can be varied by adjusting the swashplate angle. In a valve distribution structure, the swashplate rotates with the input shaft, while the piston assembly only reciprocates. Switching between suction and discharge zones is achieved by opening and closing a solenoid valve. If closed-loop control of the pump's displacement based on the external input speed is required, both of these methods necessitate the addition of an additional feedback device.

[0004] Furthermore, regardless of whether it's disc-type or valve-type flow distribution, the lubrication between the slipper and the swashplate is mostly achieved through hydrostatic support. This means the piston cavity is grooved and connected to the slipper cavity, using high-pressure leaked oil to lubricate and cool the swashplate-slipper friction pair. This grooved design leads to reduced volumetric efficiency, and the small amount of leaked oil has a poor cooling effect on the pump's internal components, resulting in significant temperature increases in the moving parts during continuous operation of the piston pump. Additionally, in the random low-speed input conditions of wind power and ocean energy generation, the presence of drain grooves further reduces the volumetric efficiency of the axial piston pump, leading to a decrease in pump performance and energy conversion efficiency.

[0005] Patent CN110848126A discloses a plunger-type digital pump, including a distribution end cover, a housing, a low-pressure valve body, a high-pressure valve body, a cylinder, a roller plunger, a distribution bearing, and an end cover. It controls nine evenly spaced low-pressure valve bodies on the cylinder via electrical signals, enabling pump output flow regulation. Its distribution function is achieved by a distribution slide fixed to the input shaft, essentially a mechanical distribution mechanism. Therefore, it lacks the ability to detect the input shaft's rotation angle and angular velocity, requiring an external feedback device to achieve closed-loop speed control. Furthermore, the slide uses a traditional drain groove hydrostatic support, resulting in significant leakage at low speeds.

[0006] Patent CN106321393A discloses an axial piston pump with an automatic displacement compensation variable speed adjusting swashplate, including a cylinder block, piston, piston sleeve, and conical spring disposed within the pump. When the speed drops to a threshold, it can automatically increase the displacement, thus widening the pump's low-speed limit to some extent. However, because the displacement adjustment is mechanical, it does not completely solve the pump's internal leakage problem. Furthermore, the pump itself lacks speed regulation functionality under low-speed conditions.

[0007] Patent CN113107800A discloses a shell-inlet forced self-cooling swashplate axial piston pump, where the oil inlet is also on the shell. The sucked-in cool oil directly cools the two pairs of friction pairs and many transmission pairs inside the pump, thereby reducing pump temperature and increasing lifespan. However, this design only improves the pump's heat dissipation performance and does not further optimize the internal leakage problem of the swashplate and slipper. Therefore, the pump has low volumetric efficiency under low-speed conditions.

[0008] Patent CN105386953B discloses a digitally distributed constant-flow radial piston pump, which mainly includes a piston chamber, a two-position three-way high-speed switching valve connecting the oil tank and the load, an absolute angle encoder connected to the crankshaft of the piston chamber, a distribution fluid, and a controller. It receives the input shaft rotation angle signal and then uses duty cycle control to achieve variable pump control. However, its inlet and outlet oil passages are both on the distribution fluid, and the slippers still use the traditional drain groove hydrostatic support form. Therefore, the problem of reduced volumetric efficiency due to internal leakage under low-speed operation still exists.

[0009] In summary, there is still room for optimization design of axial piston pumps applied to random low-speed input conditions. Summary of the Invention

[0010] The purpose of this invention is to provide a digital flow distribution and speed regulation type low-speed axial piston pump to solve the problems existing in the prior art, improve the volumetric efficiency and life of the axial piston pump, enhance the heat dissipation of the internal components of the pump, and make the pump body structure more compact.

[0011] To achieve the above objectives, the present invention provides the following solution:

[0012] This invention provides a digital flow distribution and speed regulation type low-speed axial piston pump, comprising:

[0013] The pump body is provided with an oil storage cavity and an oil passage hole. The pump body is also provided with an oil inlet and an oil outlet. One end of the oil passage hole and the oil inlet are respectively connected to the oil storage cavity.

[0014] An input shaft is rotatably coupled to the pump body and is used to connect to a drive device. One end of the input shaft extends into the oil storage cavity.

[0015] A swash plate located within the oil storage cavity, with the center of one side of the swash plate fixedly connected to one end of the input shaft that extends into the oil storage cavity;

[0016] A sliding shoe, the first side of which contacts the other side of the swashplate;

[0017] Multiple axial plungers are evenly distributed circumferentially around the axial direction of the input shaft. The axis of the axial plunger is parallel to the axis of the input shaft. Each axial plunger in the pump body has a plunger cavity. The axial plunger slides into the corresponding plunger cavity. The circumferential sidewall of the axial plunger is sealed to the inner wall of the plunger cavity. Each axial plunger has one end rotatably engaged with the second side of the slip shoe.

[0018] Multiple springs, the springs, the axial plungers and the plunger cavities correspond one-to-one, one end of each spring abuts against the end of the axial plunger away from the slipper, and the other end abuts against the end of the plunger cavity away from the slipper;

[0019] The flow channel corresponds one-to-one with the plunger cavity. One end of the flow channel is connected to the corresponding plunger cavity, and the other end is connected to the oil outlet through a one-way valve. The middle part of the flow channel is connected to the other end of the oil passage through a two-position two-way solenoid valve.

[0020] A through shaft passes through the oil passage and is coaxial with the input shaft. The through shaft is rotatably engaged with the pump body. One end of the oil passage is fixedly connected to the end of the input shaft that extends into the oil storage cavity.

[0021] The encoder is connected to one end of the through shaft that extends out of the pump body;

[0022] The controller, the encoder, and each of the two-position two-way solenoid valves are electrically connected to the controller, which is used to control the opening and closing of any one of the two-position two-way solenoid valves according to the signal fed back by the encoder.

[0023] Preferably, the swash plate is rotatably engaged with the pump body via a first bearing, and the through shaft is rotatably engaged with the pump body via two second bearings; when the digital flow distribution and speed-regulating low-speed axial piston pump is working normally, one end of the input shaft extending into the pump body, one end of the axial piston near the slipper, the swash plate, the slipper, and the first bearing are all immersed in the oil in the oil storage cavity, and the two second bearings are immersed in the oil in the oil passage.

[0024] Preferably, a guide groove is provided on the first side of the slipper, and the guide groove extends through the outer edge and inner edge of the first side of the slipper.

[0025] Preferably, the pump body is also provided with a maintenance drain port that communicates with the oil storage cavity.

[0026] Preferably, the axial plunger has a ball head at one end near the slipper, and the second side of the slipper has a spherical concave surface corresponding to the ball head, with the ball head and the corresponding spherical concave surface being rotatably engaged.

[0027] Preferably, each of the spherical concave surfaces on the slipper is provided with an oil guide hole, and the spherical concave surface communicates with the oil storage cavity through the oil guide hole.

[0028] Preferably, the material of the slipper is a gradient structure cemented carbide.

[0029] Preferably, the pump body is provided with an observation window through which the oil storage cavity can be observed.

[0030] The present invention achieves the following technical effects compared to the prior art:

[0031] The digital flow distribution and speed regulation low-speed axial piston pump of the present invention can improve the volumetric efficiency and life of the axial piston pump, enhance the heat dissipation of the internal components of the pump, and make the pump body structure more compact.

[0032] Furthermore, the digital flow distribution and speed regulation low-speed axial piston pump of the present invention transmits the angle and speed information of the input shaft to the tail end controller in the form of a through shaft, and then forms a closed-loop flow distribution and speed regulation function within the pump through the control valve group.

[0033] Furthermore, the digital flow distribution and speed regulation low-speed axial piston pump of the present invention stores hydraulic oil in an oil reservoir within the pump body, eliminating the need for an external oil tank and making the hydraulic system more compact. The hydraulic oil stored within the pump can be used as both lubricant and coolant. This increases lubrication between components within the pump, reduces component failure rates, and extends the pump's lifespan. It also facilitates heat dissipation and cooling of the pump body, preventing excessively high hydraulic oil temperatures that could reduce working efficiency, lubrication performance, and hydraulic oil lifespan.

[0034] Furthermore, by modifying the flow path, lubrication method, and control method, the drain groove in traditional plunger pumps is eliminated. This increases the pump's volumetric efficiency and overall efficiency, while reducing the machining difficulty and precision required for the axial plunger and slipper. Therefore, materials with stronger mechanical properties but less machinedability can be used to manufacture the axial plunger and slipper, thereby further improving the pump's lifespan and enhancing its adaptability.

[0035] Furthermore, the use of guide grooves enhances the oil film stiffness between the slipper and the distribution plate, thereby improving the lubrication effect. The novel ordered guide texture allows the slipper to draw in hydraulic oil for lubrication under different motion conditions, while the different guide groove widths also ensure that the slipper end face has a more uniform oil film stiffness and lubrication performance. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the digital flow distribution and speed regulation low-speed axial piston pump of the present invention.

[0038] Figure 2 This is a schematic diagram of the sliding shoe structure in the digital flow distribution and speed regulation low-speed axial piston pump of the present invention;

[0039] Figure 3 This is a schematic diagram of a portion of the sliding shoe structure in the digital flow distribution and speed regulation low-speed axial piston pump of the present invention.

[0040] Figure 4 A schematic diagram of the enhanced gradient distribution method for the slipper in the digital flow distribution and speed-regulating low-speed axial piston pump of the present invention;

[0041] Figure 5 This is a control logic diagram of a single flow channel in the digital flow distribution and speed regulation low-speed axial piston pump of the present invention.

[0042] The components are as follows: 1. Input shaft; 2. Swashplate; 3. Observation window; 4. Slipper; 5. Oil inlet; 6. Axial plunger; 7. Two-position two-way solenoid valve; 8. Check valve; 9. Oil outlet; 10. Oil reservoir; 11. Maintenance drain port; 12. Through shaft; 13. Controller; 14. Plunger cavity; 15. Oil passage; 16. Flow channel; 17. Guide groove; 18. Spherical concave surface; 19. Oil guide hole; 20. First bearing; 21. Second bearing. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0044] The purpose of this invention is to provide a digital flow distribution and speed regulation type low-speed axial piston pump to solve the problems existing in the prior art, improve the volumetric efficiency and life of the axial piston pump, enhance the heat dissipation of the internal components of the pump, and make the pump body structure more compact.

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] like Figures 1-4 As shown, this embodiment provides a digital flow distribution and speed regulation type low-speed axial piston pump, including a pump body, an input shaft 1, a swashplate 2, an axial piston 6, a spring, a through shaft 12, an encoder, and a controller 13.

[0047] The pump body includes an oil storage chamber 10 and an oil passage 15. It also has an oil inlet 5 and an oil outlet 9. One end of the oil passage 15 and the oil inlet 5 are connected to the oil storage chamber 10. Hydraulic oil enters the oil storage chamber 10 through the oil inlet 5 and fills it to 70%-95%. The hydraulic oil is stored within the oil storage chamber 10, not in an external oil tank. Therefore, the hydraulic oil circulation does not require passing through an external oil tank; it only needs to be filtered after leaving the external oil tank and before entering the oil storage chamber 10 within the pump body.

[0048] The input shaft 1 is rotatably coupled with the pump body. The input shaft 1 is used to connect the drive device. One end of the input shaft 1 extends into the oil storage cavity 10 and is driven to rotate by the drive device.

[0049] Both the swash plate 2 and the slipper 4 are located within the oil reservoir 10. The center of one side of the swash plate 2 is fixedly connected to one end of the input shaft 1 that extends into the oil reservoir 10; the first side of the slipper 4 (i.e., Figure 1 The left side of the plate 2 contacts the other side of the swashplate 2.

[0050] A guide groove 17 is also provided on the first side of the slipper 4, and the guide groove 17 runs through the outer edge and inner edge of the first side of the slipper 4. The function of the guide groove 17 is to guide the hydraulic oil in the oil storage cavity 10 to the contact surface between the slipper 4 and the swashplate 2, thereby improving the friction coefficient between the slipper 4 and the swashplate 2 and reducing friction loss. It is worth noting that the specific shape or pattern of the guide groove can be adapted to actual needs, as long as it can guide the hydraulic oil in the oil storage cavity 10 to the contact surface between the slipper 4 and the swashplate 2. Figure 2 As shown, this embodiment provides a specific form of the flow guide groove 17. Figure 2The flow guide groove 17 is divided into inner and outer rings. The outer ring consists of 12 pairs of clockwise and counterclockwise Archimedean spirals with the same starting angle. The inner ring consists of 2 pairs of orthogonal straight lines. The width of the outer flow guide groove 17 is greater than that of the inner ring to ensure that the inner and outer rings have an approximate coverage ratio. The depth of the flow guide groove 17 is 0.5-1mm.

[0051] There are multiple axial plungers 6. In practical applications, the number of axial plungers 6 can be adjusted according to actual needs. In this embodiment, there are 5 axial plungers 6. All axial plungers 6 are evenly distributed circumferentially around the axial direction of the input shaft 1. The axis of the axial plunger 6 is parallel to the axis of the input shaft 1. Each axial plunger 6 in the pump body is provided with a plunger cavity 14. The axial plunger 6 slides in fit with the corresponding plunger cavity 14. The circumferential sidewall of the axial plunger 6 is sealed with the inner wall of the plunger cavity 14. And one end of each axial plunger 6 is connected to the second side of the slip shoe 4 (i.e., Figure 1 The right side of the rotational fit, specifically:

[0052] A ball head is provided at one end of the axial plunger 6 near the slipper 4, and a spherical concave surface 18 is provided on the second side of the slipper 4 corresponding to the ball head. The ball head and the corresponding spherical concave surface 18 are rotatably engaged. Six oil guide holes 19 are provided on the slipper 4 corresponding to each spherical concave surface 18. The spherical concave surface 18 communicates with the oil storage cavity 10 through the oil guide holes 19. The center line of the oil guide hole 19 passes through the center of the spherical concave surface 18, and the diameter of the oil guide hole 19 is no greater than 5mm. The design of the oil guide hole 19 reduces the friction between the spherical concave surface 18 and the ball head.

[0053] The spring, axial plunger 6, and plunger cavity 14 correspond one-to-one. The spring is located inside the plunger cavity 14. One end of the spring abuts against the end of the axial plunger 6 away from the slipper 4, and the other end abuts against the end of the plunger cavity 14 away from the slipper 4. Under the action of the spring's elastic force, a force is applied to the axial plunger 6 so that the first side of the slipper 4 is always in close contact with the swashplate 2.

[0054] This embodiment of the digital flow distribution and speed-regulating low-speed axial piston pump also includes flow channels 16 corresponding one-to-one with the piston chambers 14, so as to... Figure 1 From the perspective of the flow channel 16, the left end of the flow channel 16 is connected to the corresponding plunger cavity 14, and the right end is connected to the oil outlet 9 through the one-way valve 8. The middle part of the flow channel 16 is connected to the right end of the oil passage 15 through the two-position two-way solenoid valve 7.

[0055] The through shaft 12 passes through the oil passage hole 15 and is coaxial with the input shaft 1. The through shaft 12 is rotatably engaged with the pump body. One end of the oil passage hole 15 is fixedly connected to the end of the input shaft 1 that extends into the oil storage cavity 10. The encoder is connected to the end of the through shaft 12 that extends out of the pump body. When the drive device drives the input shaft 1 to rotate, the input shaft 1 drives the coaxial shaft to rotate together. The encoder can convert the rotational displacement of the through shaft 12 into a series of digital pulse signals.

[0056] The swash plate 2 is rotatably engaged with the pump body via the first bearing 20, and the through shaft is rotatably engaged with the pump body via two second bearings 21. When the digital flow distribution and speed regulation type low-speed axial piston pump of this embodiment is working normally, the end of the input shaft 1 that extends into the pump body, the end of the axial piston 6 that is close to the slipper 4, the swash plate 2, the slipper 4 and the first bearing 20 are all immersed in the oil in the oil storage cavity 10, and the two second bearings 21 are immersed in the oil in the oil passage 15.

[0057] The pump body is equipped with an observation window 3, through which the oil storage chamber 10 can be observed. When the pump is in operation, the operator can observe the internal condition of the oil storage chamber 10 through the observation window 3. The pump body is also equipped with a maintenance drain port 11 that communicates with the oil storage chamber 10. When disassembly or maintenance is required, hydraulic oil can be released from the maintenance drain port 11.

[0058] To increase the surface hardness and wear resistance of the end face of the slipper 4, the material of the slipper 4 is a gradient structure cemented carbide, and its reinforcing phase can be tin, aluminum, or manganese, etc. The distribution density of the reinforcing phase of the slipper 4 is as follows: Figure 4 As shown, the slope decreases along the vertical surface of the slipper 4 towards the spherical concave surface 18.

[0059] The encoder and each 2-position 2-way solenoid valve 7 are electrically connected to the controller 13, which controls the opening and closing of any one of the 2-position 2-way solenoid valves 7 based on the signal fed back from the encoder. The controller 13 measures and calculates the angle and angular velocity of the input shaft 1 based on the signal fed back from the encoder to determine the timing for opening and closing the 2-position 2-way solenoid valve 7.

[0060] The specific working principle of the digital flow distribution and speed regulation low-speed axial piston pump in this embodiment is as follows:

[0061] When the pump enters the working state, the input shaft 1 drives the swashplate 2 to rotate. The rotation of the swashplate 2 causes the slipper 4 to swing and move axially, thereby causing the axial piston 6 to move axially. When the axial piston 6 moves axially, the change in volume of the piston cavity 14 (excluding the axial piston 6) is coordinated with the opening and closing of the two-position two-way solenoid valve 7 to complete the oil suction and discharge.

[0062] Taking the working process of a single flow channel 16 as an example, if combined with Figure 1 and Figure 5As shown, when the axial plunger 6 extends to the left, the two-position two-way solenoid valve 7 opens, and the plunger cavity 14 is connected to the oil passage 15. At this time, the one-way valve 8 automatically closes, preventing the flow channel branch from being affected by the pressure changes of other flow channel branches. The hydraulic oil in the oil storage cavity 10 enters the plunger cavity 14 through the oil passage 15, completing the oil suction action. When the axial plunger 6 moves to the right and is pushed into the plunger cavity 14, the pressure in the cavity to the right of the axial plunger 6 increases. If the two-position two-way solenoid valve 7 closes at this time, the plunger cavity 14 is disconnected from the oil passage 15, and the check valve 8 will automatically open under high pressure. The hydraulic oil enters the external load through the oil outlet 9 to complete the oil discharge action. If the two-position two-way solenoid valve 7 remains open, the plunger cavity 14 is connected to the oil passage 15. Since the pressure in the oil storage cavity 10 and the oil passage 15 is very low, while the oil pressure of the external load is high, the check valve 8 will remain closed under the action of its own spring. The hydraulic oil in the plunger cavity 14 will be discharged back into the oil storage cavity 10 through the oil passage 15 to complete the no-load action.

[0063] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A digital flow distribution and speed regulation low speed axial piston pump, characterized in that, include: The pump body is provided with an oil storage cavity and an oil passage hole. The pump body is also provided with an oil inlet and an oil outlet. One end of the oil passage hole and the oil inlet are respectively connected to the oil storage cavity. An input shaft is rotatably coupled to the pump body and is used to connect to a drive device. One end of the input shaft extends into the oil storage cavity. A swash plate located within the oil storage cavity, with the center of one side of the swash plate fixedly connected to one end of the input shaft that extends into the oil storage cavity; The sliding shoe has a first side that contacts the other side of the swashplate. A flow guide groove is provided on the first side of the sliding shoe, and the flow guide groove runs through the outer edge and inner edge of the first side of the sliding shoe. The flow guide groove is divided into two rings, an outer ring consisting of 12 pairs of clockwise and counterclockwise Archimedean spirals, and an inner ring consisting of 2 pairs of orthogonal straight lines. The depth of the flow guide groove is 0.5-1mm. Multiple axial plungers are evenly distributed circumferentially around the axial direction of the input shaft. The axis of the axial plunger is parallel to the axis of the input shaft. Each axial plunger in the pump body has a plunger cavity. The axial plunger slides into the corresponding plunger cavity. The circumferential sidewall of the axial plunger is sealed to the inner wall of the plunger cavity. Each axial plunger has one end rotatably engaged with the second side of the slip shoe. The axial plunger has a ball head at one end near the slipper, and a spherical concave surface is provided on the second side of the slipper corresponding to the ball head. The ball head and the corresponding spherical concave surface are rotatably engaged. Each spherical concave surface on the slipper has an oil guide hole. The spherical concave surface communicates with the oil storage cavity through the oil guide hole. The center line of the oil guide hole passes through the center of the corresponding spherical concave surface. There is a gap between the end of the oil guide hole away from the corresponding spherical concave surface and the first side of the slipper. Multiple springs, the springs, the axial plungers and the plunger cavities correspond one-to-one, one end of each spring abuts against the end of the axial plunger away from the slipper, and the other end abuts against the end of the plunger cavity away from the slipper; The flow channel corresponds one-to-one with the plunger cavity. One end of the flow channel is connected to the corresponding plunger cavity, and the other end is connected to the oil outlet through a one-way valve. The middle part of the flow channel is connected to the other end of the oil passage through a two-position two-way solenoid valve. A through shaft passes through the oil passage and is coaxial with the input shaft. The through shaft is rotatably engaged with the pump body. One end of the through shaft is fixedly connected to the end of the input shaft that extends into the oil storage cavity. The encoder is connected to one end of the through shaft that extends out of the pump body; The controller, the encoder, and each of the two-position two-way solenoid valves are electrically connected to the controller, which is used to control the opening and closing of any one of the two-position two-way solenoid valves according to the signal fed back by the encoder.

2. The low speed axial piston pump of claim 1, wherein: The swash plate is rotatably engaged with the pump body via a first bearing, and the through shaft is rotatably engaged with the pump body via two second bearings. When the digital flow distribution and speed-regulating low-speed axial piston pump is working normally, one end of the input shaft extending into the pump body, one end of the axial piston near the slipper, the swash plate, the slipper, and the first bearing are all immersed in the oil in the oil storage cavity, and the two second bearings are immersed in the oil in the oil passage.

3. The low speed axial piston pump of claim 1, wherein: The pump body is also equipped with a maintenance drain port that communicates with the oil storage cavity.

4. The digital flow distribution and speed regulation low-speed axial piston pump according to claim 1, characterized in that: The material of the slipper is a gradient structure cemented carbide.

5. The digital flow distribution and speed regulation low-speed axial piston pump according to claim 1, characterized in that: The pump body is provided with an observation window, through which the oil storage cavity can be observed.

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