Double-variable plunger pump motor

Abstract

The invention discloses a double-variable plunger pump motor. The problem that a variable pump and a variable motor in an existing system are generally two products and are controlled independently is solved. The speed reducer comprises a shell which is provided with a containing cavity, and further comprises an input shaft, an output shaft and an output shaft, a first plunger assembly; the first variable component comprises a first variable cylinder and a first swash plate; the output shaft and the input shaft are arranged in a staggered manner; the second plunger assembly is arranged in the shell and shares a containing cavity with the first plunger assembly; the second variable component comprises a second variable cylinder and a second swash plate; the first oil supplementing pump assembly is driven by the input shaft to rotate and used for supplementing oil for the oil duct during starting; the first oil supplementing pump assembly is connected with the first variable cylinder and the second variable cylinder and used for driving the first variable cylinder and / or the second variable cylinder to act. The invention has the advantages of simple structure, convenience in assembly, reliable action, long service life and the like.

Description

Technical Field

[0001] The present invention relates to a dual-variable pump motor, in particular to a dual-variable plunger pump motor. Background Art

[0002] A plunger pump is a crucial component of hydraulic systems and is generally classified as either axial or radial. It relies on the reciprocating motion of a plunger within a cylinder, causing the volume of a sealed working chamber to change, thereby absorbing and discharging oil. Plunger pumps are widely used in applications requiring high pressure, high flow rates, and where flow regulation is required, such as hydraulic presses, construction machinery, and ships. When the plunger pump is operating, the main shaft drives the plunger in an up-and-down reciprocating motion (although other oscillating or rotating parts can also drive this reciprocating motion), causing the cylinder to absorb and discharge oil through the oil distribution plate, completing the pumping task.

[0003] A hydraulic motor is an actuator in a hydraulic system. It converts the fluid pressure energy provided by a hydraulic pump into mechanical energy (torque and speed) on its output shaft. The fluid is the medium that transmits force and motion. Hydraulic motors, also known as oil motors, are primarily used in injection molding machinery, ships, hoists, engineering machinery, construction machinery, coal mining machinery, mining machinery, metallurgical machinery, marine machinery, petrochemical industry, and port machinery. In existing equipment, during operation, the engine drives the main shaft of the plunger pump. The plunger pump's oil suction and discharge drive the motor. Hydraulic oil flows through the motor's oil distribution plate into the motor's cylinder, driving the plunger and rotating the cylinder. The cylinder then drives the motor, which in turn drives the motor's output shaft, driving components such as the reducer. The pump and motor are typically separate components, physically isolated from each other and externally connected by hydraulic piping. This results in a large size, complex structure, and numerous components, leading to high cost. Furthermore, the pump and motor take up considerable space, making assembly difficult and time-consuming. Existing single-variable pumps on the market also feature output shafts with motor functionality, but these dual-shaft designs are bulky, and the pump and motor components controlling oil suction and discharge only manage a displacement of approximately 55ml / rev, effectively limiting their operation to small displacements. Because these products utilize only a single-variable pump, the motor's speed can only be reduced by varying the pump's displacement under varying operating conditions. This reduced motor speed reduces output torque, creating a "small horse pulling a large cart" phenomenon during operation. Furthermore, due to the pump's characteristics, output performance is typically stable at maximum load pressure (maximum displacement). However, varying the pump's displacement, especially at low displacements, can compromise output stability, hindering precise system control. Summary of the Invention

[0004] In order to solve the problem in the prior art that the variable pump and the variable motor in the existing system are usually two products and are controlled independently of each other, the present invention provides a dual-variable plunger pump motor.

[0005] The technical solution of the present invention is: a dual-variable piston pump motor, comprising a housing, wherein the housing is provided with an accommodating cavity, and further comprising: An input shaft is inserted into the housing; A first plunger assembly is disposed in the accommodating cavity, and the first plunger assembly includes a first cylinder body and a first plunger; the input shaft drives the first cylinder body to rotate and realizes oil suction and oil discharge through the first plunger; A first variable component, the first variable component comprising a first variable cylinder and a first swash plate, the first plunger abutting against the first swash plate; the first variable cylinder is connected to the first swash plate and controls the oil suction and discharge amounts through the swing of the first swash plate; An output shaft extends from the housing; the output shaft and the input shaft are staggered; A second plunger assembly is disposed within the housing and shares a housing cavity with the first plunger assembly; the second plunger assembly includes a second cylinder body and a second plunger; the second plunger absorbs and discharges oil by moving relative to the second cylinder body; the second cylinder body is connected to the output shaft and is used to drive the output shaft to rotate; A second variable displacement assembly, comprising a second variable displacement cylinder and a second swash plate, wherein the second plunger abuts against the second swash plate; the second variable displacement cylinder is connected to the second swash plate and controls the oil suction and discharge amounts through the swing of the second swash plate, thereby controlling the rotational speed of the output shaft; The first oil replenishment pump assembly is driven to rotate by the input shaft and is used to replenish oil to the oil channel during startup; the first oil replenishment pump assembly is respectively connected to the first variable cylinder and the second variable cylinder and is used to drive the first variable cylinder and / or the second variable cylinder to move.

[0006] As a further improvement of the present invention, the first oil replenishment pump assembly replenishes oil to the first cylinder and the second cylinder through the oil channel inside the shell when started. The first oil replenishment pump assembly drives the first swash plate and the second swash plate to move through the first variable cylinder and the second variable cylinder respectively, thereby changing the displacement of the corresponding first plunger assembly and the second plunger assembly.

[0007] As a further improvement of the present invention, the first oil charge pump assembly includes internal teeth and external teeth, the input shaft is connected to the internal teeth and is used to drive the internal teeth to rotate, and the internal teeth drive the external teeth to rotate to achieve oil suction and discharge.

[0008] As a further improvement of the present invention, the inner teeth are arranged concentrically with the input shaft, and the outer teeth are arranged eccentrically with the inner teeth.

[0009] As a further improvement of the present invention, the first oil charge pump assembly is arranged on the input shaft and driven to rotate by the input shaft. The first oil charge pump assembly is arranged on the input shaft on the other side of the first swash plate relative to the first cylinder block.

[0010] As a further improvement of the present invention, a second oil replenishment pump assembly is further included, which is driven by the input shaft to rotate to achieve oil suction and oil discharge, and is used to supply oil to the external brake.

[0011] As a further improvement of the present invention, a filter element is further included, through which the pressure oil of the first oil replenishment pump assembly is input to the first variable cylinder and the second variable cylinder for realizing variable control.

[0012] As a further improvement of the present invention, it also includes an external oil control pipe, one end of which is connected to the connector, and the other end is connected to the second variable cylinder. The first oil replenishment pump assembly is connected to the second variable cylinder through the connector and the external oil control pipe for oil replenishment control of the second variable cylinder.

[0013] As a further improvement of the present invention, it also includes a ferrule, which is configured to be contracted at one end and opened at the other end, and the external control oil pipe is arranged through the ferrule; the ferrule also includes a tapered surface and a locking surface; the tapered surface is inserted into the connecting head and contracts to clamp the external control oil pipe; the connecting head is provided with a locking nut, and the locking nut and the locking surface of the ferrule cooperate with each other to lock the external control oil pipe.

[0014] As a further improvement of the present invention, it also includes: An oil replenishment relief valve, the oil replenishment relief valve being provided between the first oil replenishment pump assembly and the first variable cylinder; A high-pressure relief valve is used to return high-pressure oil in the housing; the opening pressure of the high-pressure relief valve is greater than the opening pressure of the oil supply relief valve; An oil replenishment check valve, wherein the first oil replenishment pump assembly replenishes oil to the oil passage in the housing through the oil replenishment check valve when the first oil replenishment pump assembly is started; The first control valve, the first oil charge pump assembly is connected to the first variable cylinder through the first control valve to drive the first variable cylinder to move; The second control valve, the first oil replenishment pump assembly is connected to the second variable cylinder through the second control valve to drive the first variable cylinder to move; the second control valve is an electromagnetic reversing valve.

[0015] The present invention has the beneficial effect of arranging a first plunger assembly, a first variable displacement assembly, a second plunger assembly, and a second variable displacement assembly within a housing, achieving an integrated arrangement that simultaneously realizes the functions of a variable displacement pump and a variable displacement motor. This simplifies the number of components, achieves variable displacement output, and provides a wide range of product adaptability, enabling the variable displacement pump to achieve stable output while the variable displacement motor to adapt to different operating conditions. The present invention also has the advantages of a simple structure, easy assembly, reliable operation, and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Attachment Figure 1 Schematic diagram of the structure of an embodiment of the present invention.

[0017] Attachment Figure 2 This is a structural diagram of another embodiment of the present invention.

[0018] Attachment Figure 3 This is a structural diagram of another embodiment of the present invention.

[0019] Attachment Figure 4 For attachment Figure 3 Schematic diagram of the cross-sectional structure of AA.

[0020] Attachment Figure 5 This is a structural diagram of another embodiment of the present invention.

[0021] Attachment Figure 6 For attachment Figure 5 Schematic diagram of the cross-sectional structure of BB.

[0022] Attachment Figure 7 For attachment Figure 5 Schematic diagram of the cross-sectional structure of CC.

[0023] Attachment Figure 8 For attachment Figure 3 Schematic diagram of the enlarged structure at point I.

[0024] Attachment Figure 9 Schematic diagram of the structure of the first oil charge pump assembly according to an embodiment of the present invention.

[0025] Attachment Figure 10 Schematic diagram of the structure of the second oil charge pump assembly according to an embodiment of the present invention.

[0026] Attachment Figure 11 Schematic diagram of the hydraulic principle of an embodiment of the present invention.

[0027] In the figure, 1. housing; 11. oil-supply relief valve; 12. high-pressure relief valve; 13. oil-supply check valve; 14. first control valve; 15. second control valve; 16. oil channel; 2. accommodating chamber; 31. input shaft; 32. first plunger assembly; 321. first cylinder body; 322. first plunger; 33. first variable assembly; 331. first variable cylinder; 332. first swash plate; 41. output shaft; 42. second plunger assembly; 421. second cylinder body; 422. second plunger; 43. second variable assembly; 431. second variable cylinder; 432. second swash plate; 5. first oil-supply pump assembly; 51. internal gear; 52. external gear; 6. second oil-supply pump assembly; 7. filter element; 81. external oil control pipe; 82. connector; 83. ferrule; 831. tapered surface; 832. locking surface; 84. locking nut. DETAILED DESCRIPTION

[0028] The embodiments of the present invention will be further described below with reference to the accompanying drawings: Depend on Figure 1Combine Figure 2-11 As shown, a dual-variable piston pump motor includes a housing 1, wherein the housing 1 is provided with a receiving cavity 2, and is characterized in that it also includes: Input shaft 31, inserted into housing 1; The first plunger assembly 32 is arranged in the accommodating chamber 2. The first plunger assembly 32 includes a first cylinder body 321 and a first plunger 322. The input shaft 31 drives the first cylinder body 321 to rotate and realizes oil suction and oil discharge through the first plunger 322. In fact, the pump drives the first cylinder body to rotate by the rotation of the input shaft, and realizes oil suction and oil discharge through the first plunger and the oil distribution plate, wherein the oil distribution plate can be realized by using existing technology. The motor drives the output shaft to rotate by hydraulic oil, and the second cylinder body of the motor is also provided with an oil distribution plate. This is a common design in the mechanical structure of pumps and motors, and will not be described in detail again. A first variable displacement assembly 33 includes a first variable displacement cylinder 331 and a first swash plate 332. The first plunger 322 abuts against the first swash plate 332. The first variable displacement cylinder 331 is connected to the first swash plate 332 and controls the oil suction and discharge amounts through the swing of the first swash plate 332. The output shaft 41 extends from the housing 1; the output shaft 41 is staggered with the input shaft 31; The second plunger assembly 42 is disposed within the housing 1 and shares the accommodating chamber 2 with the first plunger assembly 32. The second plunger assembly 42 includes a second cylinder 421 and a second plunger 422. The second plunger 422 absorbs and discharges oil by moving relative to the second cylinder 421. The second cylinder 421 is connected to the output shaft 41 and is used to drive the output shaft 41 to rotate. The second variable displacement assembly 43 includes a second variable displacement cylinder 431 and a second swash plate 432. The second plunger 422 abuts against the second swash plate 432. The second variable displacement cylinder 431 is connected to the second swash plate 432 and controls the oil suction and discharge amounts through the swing of the second swash plate 432, thereby controlling the rotational speed of the output shaft 41. The first charge pump assembly 5 is driven by the input shaft 31 for rotation and is used to replenish oil to the oil passage 16 during startup. The first charge pump assembly 5 is connected to the first variable cylinder 331 and the second variable cylinder 431, respectively, and is used to actuate the first variable cylinder 331 and / or the second variable cylinder 431. The present invention advantageously integrates the first plunger assembly, the first variable assembly, the second plunger assembly, and the second variable assembly within the housing, achieving an integrated arrangement that simultaneously functions as a variable pump and a variable motor. This simplifies component parts, achieves variable output, and broadens product compatibility, enabling stable output from the variable pump and adaptable output from the variable motor to various operating conditions. The present invention also offers advantages such as a simple structure, easy assembly, reliable operation, and a long service life. In the present invention, the input shaft, the first plunger assembly, and the first variable assembly constitute key components of the variable pump, while the output shaft, the second plunger assembly, and the second variable assembly constitute key components of the variable motor. For ease of description, this document will also refer to the variable pump or variable motor as such. The present invention significantly reduces product size. The variable pump displacement of the present invention can reach more than 60 ml / rev, and the motor oil suction and discharge can reach more than 73 ml / rev. This is of great significance in specific systems and actual work. Taking agricultural machinery as an example, when agricultural machinery such as rice harvesters and the cutting platform in crawler harvesters are working, large torque is required, so it is necessary to revolve the pump at a large speed, and the motor speed becomes smaller, thereby outputting a larger torque; and when transferring or driving, in order to facilitate travel or reduce energy consumption, the motor speed needs to be increased and the torque output needs to be reduced. The present invention can realize the change of the motor output shaft speed under the condition of large pump displacement, can adapt to different working conditions, and has higher stability.

[0029] During startup, the first charge pump assembly 5 replenishes oil to the first cylinder 321 and the second cylinder 421 through the internal oil passage 16 of the housing 1. The first charge pump assembly 5 drives the first swash plate 332 and the second swash plate 432 via the first variable cylinder 331 and the second variable cylinder 431, respectively, thereby varying the displacement of the corresponding first plunger assembly 32 and the second plunger assembly 42. This simple structure allows for convenient and reliable control, thereby enabling control of both pump and motor displacements, and thus controlling the motor's output speed.

[0030] The first charge pump assembly 5 includes internal teeth 51 and external teeth 52. The input shaft 31 is connected to the internal teeth 51 and is used to drive the internal teeth 51 to rotate. The internal teeth 51 drives the external teeth 52 to rotate to achieve oil suction and discharge. Specifically, the internal teeth 51 are arranged concentrically with the input shaft 31, while the external teeth 52 are arranged eccentrically with the internal teeth 51. Due to the eccentric arrangement of the external teeth, an oil channel is formed between the internal teeth. When the input shaft rotates, the oil flow area of ​​the oil channel changes, thereby achieving oil suction and discharge. This allows the input shaft to reliably perform the charge pump function, supplying oil to the oil channel within the housing and the first and second variable cylinders, facilitating the implementation of the variable pump and variable motor functions.

[0031] The first oil replenishment pump assembly 5 is disposed on the input shaft 31 and is driven to rotate by the input shaft 31. The first oil replenishment pump assembly 5 is disposed on the input shaft 31 on the other side of the first swash plate 332 relative to the first cylinder body 321. Specifically, the present invention also includes a second oil replenishment pump assembly 6, which is driven to rotate by the input shaft 31 to achieve oil suction and discharge, and is used to supply oil to the external brake. The provision of the second oil replenishment pump assembly facilitates external brakes, making product control more convenient and reliable. Both the first oil replenishment pump assembly and the second oil replenishment pump assembly are driven by the input shaft. In fact, the second oil replenishment pump assembly also includes internal and external teeth, but the structure of the internal and external teeth is different from the specific structure of the first oil replenishment pump assembly. It also achieves oil suction and discharge by driving the external teeth to rotate by the internal teeth, and when the external teeth rotate, the volume of the oil passage chamber changes.

[0032] The present invention also includes a filter element 7, through which the pressure oil of the first oil charge pump assembly 5 is input to the first variable cylinder 331 and the second variable cylinder 431 for variable control. The filter element can filter impurities to prevent them from entering and affecting product performance.

[0033] The present invention also includes an external oil control pipe 81, one end of which is connected to a connector 82 and the other end to the second variable cylinder 431. The first oil charge pump assembly 5 is connected to the second variable cylinder 431 via the connector 82 and the external oil control pipe 81 for controlling oil charge to the second variable cylinder 431. Specifically, the present invention also includes a ferrule 83, which is configured to be contracted at one end and expanded at the other. The external oil control pipe 81 is passed through the ferrule 83. The ferrule 83 also includes a tapered surface 831 and a locking surface 832. The tapered surface 831 is inserted into the connector 82 and contracts to clamp the external oil control pipe 81. The connector 82 is provided with a locking nut 84, which cooperates with the locking surface 832 of the ferrule 83 to lock the external oil control pipe 81. This structure facilitates the securement of the external oil control pipe and maintains a simple structure. Specifically, the setting of the ferrule can clamp the external control oil pipe through the tapered surface, and the locking nut can be reliably connected to the connector thread. At the same time, the locking nut and the locking surface of the ferrule cooperate with each other to limit the ferrule and the external control oil pipe.

[0034] The present invention also includes: The oil replenishment relief valve 11 is provided between the first oil replenishment pump assembly 5 and the first variable cylinder 331; The high-pressure relief valve 12 is used to return the high-pressure oil in the housing; the opening pressure of the high-pressure relief valve 12 is greater than the opening pressure of the oil supply relief valve 11; The oil replenishment check valve 13, when the first oil replenishment pump assembly 5 is started, replenishes oil to the oil passage 16 in the housing 1 through the oil replenishment check valve 13; The first control valve 14, the first oil charge pump assembly 5 is connected to the first variable cylinder 331 through the first control valve 14 to drive the first variable cylinder 331 to operate; The second control valve 15, the first oil replenishment pump assembly 5 is connected to the second variable cylinder 431 through the second control valve 15 to drive the first variable cylinder 331 to operate; the second control valve 15 is an electromagnetic reversing valve. The setting of the oil replenishment relief valve makes the system safer. When the first oil replenishment pump assembly is working, it will replenish the oil channel in the housing with hydraulic oil to facilitate the operation of the plunger pump. Excess hydraulic oil will be trapped at the first control valve to quickly enter the first variable cylinder to control the displacement of the plunger pump. Excess hydraulic oil will return to the oil tank through the oil replenishment relief valve. The setting of the high-pressure relief valve makes the system safer. If the hydraulic oil in the oil channel of the housing exceeds the set pressure, the high-pressure relief valve will be opened. Since the opening pressure of the high-pressure relief valve is greater than the opening pressure of the oil replenishment relief valve, the oil replenishment relief valve will also be opened at this time, facilitating rapid oil discharge, and the product has higher safety performance. The setting of the oil replenishment check valve facilitates rapid oil replenishment of the first oil replenishment pump assembly, has a simple structure, and avoids oil return. Specifically, the first control valve is an electro-proportional pressure-reducing valve, and there are two of them. This facilitates precise control of the oil inlet volume. That is, when one electro-proportional pressure-reducing valve is energized, the oil-supply check valve replenishes oil to the rod chamber or rodless chamber of the first variable cylinder connected to the electro-proportional pressure-reducing valve. At this time, the piston of the first variable cylinder drives the displacement of the plunger pump, thereby controlling the plunger pump to change from small displacement to large displacement or from large displacement to small displacement. The second control valve can reliably supply oil to the rod chamber or rodless chamber of the second variable cylinder, achieving a change in motor displacement and thus changing the motor speed. Specifically, it can achieve high torque and fast speed switching to adapt to different operating conditions.

[0035] In the description of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium, or they can refer to internal connections between two components. A person of ordinary skill in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0037] Technical personnel should note: Although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention. Any modification using the inventive concept will be included in the scope of protection of the patent right of the present invention.

Claims

1. A dual-variable piston pump motor, comprising a housing (1), wherein the housing (1) is provided with a receiving cavity (2), characterized in that: Also includes: An input shaft (31) is inserted into the housing (1); A first plunger assembly (32) is disposed in the accommodating chamber (2), the first plunger assembly (32) comprising a first cylinder body (321) and a first plunger (322); the input shaft (31) drives the first cylinder body (321) to rotate and achieves oil suction and oil discharge through the first plunger (322); A first variable component (33), the first variable component (33) comprising a first variable cylinder (331) and a first swash plate (332), the first plunger (322) abutting against the first swash plate (332); the first variable cylinder (331) is connected to the first swash plate (332) and controls the oil suction and discharge amounts through the swing of the first swash plate (332); An output shaft (41) extends from the housing (1); the output shaft (41) and the input shaft (31) are arranged in an offset manner; A second plunger assembly (42) is disposed in the housing (1) and shares a receiving chamber (2) with the first plunger assembly (32); the second plunger assembly (42) comprises a second cylinder (421) and a second plunger (422); the second plunger (422) absorbs and discharges oil by moving relative to the second cylinder (421); the second cylinder (421) is connected to the output shaft (41) and is used to drive the output shaft (41) to rotate; A second variable component (43), the second variable component (43) comprising a second variable cylinder (431) and a second swash plate (432), the second plunger (422) abutting against the second swash plate (432); the second variable cylinder (431) is connected to the second swash plate (432) and controls the oil suction and discharge amounts through the swing of the second swash plate (432) to control the rotation speed of the output shaft (41); The first oil replenishing pump assembly (5) is driven to rotate by the input shaft (31) and is used to replenish oil to the oil passage (16) during startup; the first oil replenishing pump assembly (5) is respectively connected to the first variable cylinder (331) and the second variable cylinder (431) and is used to drive the first variable cylinder (331) and / or the second variable cylinder (431) to operate.

2. A dual variable piston pump motor according to claim 1, characterized in that When the first oil replenishing pump assembly (5) is started, the oil replenishing pump assembly (5) replenishes the first cylinder (321) and the second cylinder (421) through the oil passage (16) inside the housing (1). The first oil replenishing pump assembly (5) drives the first swash plate (332) and the second swash plate (432) to move through the first variable cylinder (331) and the second variable cylinder (431), respectively, thereby changing the displacement of the corresponding first plunger assembly (32) and the second plunger assembly (42).

3. A dual variable piston pump motor according to claim 1, characterized in that The first oil replenishment pump assembly (5) comprises an inner tooth (51) and an outer tooth (52). The input shaft (31) is connected to the inner tooth (51) and is used to drive the inner tooth (51) to rotate. The inner tooth (51) drives the outer tooth (52) to rotate to achieve oil suction and oil discharge.

4. A dual variable piston pump motor according to claim 3, characterized in that The inner teeth (51) are arranged concentrically with the input shaft (31), and the outer teeth (52) are arranged eccentrically with the inner teeth (51).

5. A dual variable piston pump motor according to claim 1, characterized in that The first oil replenishment pump assembly (5) is arranged on the input shaft (31) and is driven to rotate by the input shaft (31). The first oil replenishment pump assembly (5) is arranged on the input shaft (31) on the other side of the first swash plate (332) relative to the first cylinder block (321).

6. A dual variable piston pump motor according to claim 1, characterized in that It also includes a second oil replenishment pump assembly (6), which is driven by the input shaft (31) to rotate to absorb and discharge oil, and is used to supply oil to the external brake.

7. A dual variable piston pump motor according to claim 1, characterized in that It also includes a filter element (7), and the pressure oil of the first oil replenishment pump assembly (5) is input into the first variable cylinder (331) and the second variable cylinder (431) through the filter element (7) to achieve variable control.

8. The dual variable piston pump motor according to claim 1, characterized in that The invention also includes an external oil control pipe (81), one end of which is connected to a connector (82), and the other end of which is connected to a second variable cylinder (431). The first oil replenishment pump assembly (5) is connected to the second variable cylinder (431) via the connector (82) and the external oil control pipe (81) for oil replenishment control of the second variable cylinder (431).

9. A dual variable piston pump motor according to claim 8, characterized in that The outer control oil pipe (81) is passed through the ferrule (83); the ferrule (83) further comprises a tapered surface (831) and a locking surface (832); the tapered surface (831) is inserted into the connector (82) and contracts to clamp the outer control oil pipe (81); a locking nut (84) is provided on the connector (82); the locking nut (84) and the locking surface (832) of the ferrule (83) cooperate with each other to lock the outer control oil pipe (81).

10. The dual variable piston pump motor according to claim 1, characterized in that Also includes: An oil replenishment overflow valve (11), the oil replenishment overflow valve (11) being arranged between the first oil replenishment pump assembly (5) and the first variable cylinder (331); A high-pressure relief valve (12) is used for returning high-pressure oil in the housing; the opening pressure of the high-pressure relief valve (12) is greater than the opening pressure of the oil supply relief valve (11); An oil replenishment check valve (13), wherein the first oil replenishment pump assembly (5) replenishes oil to the oil passage (16) in the housing (1) through the oil replenishment check valve (13) when starting; A first control valve (14), wherein the first oil replenishment pump assembly (5) is connected to the first variable cylinder (331) via the first control valve (14) to drive the first variable cylinder (331) to operate; The second control valve (15), the first oil replenishment pump assembly (5) is connected to the second variable cylinder (431) through the second control valve (15) to drive the first variable cylinder (331) to operate; the second control valve (15) is an electromagnetic reversing valve.

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