A pump-valve combination device applied to a hydraulic system of an engineering vehicle

Abstract

The application discloses a pump-valve combined device applied to an engineering vehicle hydraulic system, and aims to provide a pump-valve combined device which realizes automatic switching of clutch oil circuit and brake oil circuit through automatic mechanical structure control and adjustment, thereby effectively improving the reliability and stability of hydraulic system oil circuit switching. The pump-valve combined device comprises an oil pump, an oil circuit switching valve and a gear box. The oil pump is used for supplying lubricating oil to the gear box and comprises a pump oil inlet and a pump oil outlet. The oil circuit switching valve is used for controlling the on-off of the clutch oil circuit and the brake oil circuit of the engineering vehicle. The oil circuit switching valve comprises a valve body, a valve core cavity arranged in the valve body, a shift valve core and a shift spring which are slidably arranged in the valve core cavity. The valve body is provided with a clutch oil circuit inlet, a clutch oil circuit outlet, a brake oil circuit inlet and a brake oil circuit outlet. The pump oil outlet and one end of the valve core cavity are connected in communication through a shift oil circuit. One end of the shift spring abuts against the other end of the valve core cavity, and the other end of the shift spring abuts against the shift valve core.

Description

Technical Field

[0001] This invention relates to the field of hydraulic systems for engineering vehicles, and more specifically to a pump and valve assembly used in hydraulic systems for engineering vehicles. Background Technology

[0002] An existing hydraulic system for engineering vehicles includes an oil pump, a clutch circuit, and a brake circuit. The oil pump supplies lubricating oil to the transmission, and its power comes from the engine, which transmits power to the pump's drive shaft via a transmission mechanism. Switching between the clutch and brake circuits is controlled by a solenoid valve combined with a sensor and a controller. Specifically, the sensor detects the pump's input speed. When the input speed is greater than or equal to a set value, the solenoid valve disengages the clutch circuit and engages the brake circuit; conversely, when the input speed is less than the set value, the solenoid valve engages the clutch circuit and disengages the brake circuit. This hydraulic system's circuit switching operation requires a control program and suffers from poor stability. Failure of any component—the solenoid valve, sensor, or controller—can lead to the failure of the circuit switching function. Summary of the Invention

[0003] The purpose of this invention is to provide a pump and valve combination device for use in the hydraulic system of engineering vehicles, which achieves automatic switching between clutch and brake oil circuits through automatic control and adjustment of mechanical structure, thereby effectively improving the reliability and stability of hydraulic system oil circuit switching control.

[0004] The technical solution of this invention is:

[0005] A pump and valve assembly for use in the hydraulic system of an engineering vehicle, comprising:

[0006] An oil pump is used to supply lubricating oil to the transmission. The oil pump includes an oil inlet and an oil outlet.

[0007] The hydraulic circuit switching valve is used to control the on / off state of the clutch hydraulic circuit and the brake hydraulic circuit of the engineering vehicle.

[0008] The oil circuit switching valve includes a valve body, a valve core cavity disposed within the valve body, a shift valve core slidably disposed within the valve core cavity, and a shift spring disposed within the valve core cavity. The valve body is provided with a clutch oil circuit inlet, a clutch oil circuit outlet, a brake oil circuit inlet, and a brake oil circuit outlet. The pump outlet is connected to one end of the valve core cavity through a shift oil circuit. One end of the shift spring abuts against the other end of the valve core cavity, and the other end of the shift spring abuts against the shift valve core.

[0009] The oil circuit switching valve includes a brake position and a clutch position. When the input speed of the oil pump is greater than or equal to the set value n1, the oil pressure exerted by the oil pump on the shift valve core through the pump outlet and the shift oil circuit will overcome the force of the shift spring, causing the oil circuit switching valve to switch from the clutch position to the brake position. At this time, the brake oil circuit inlet and the brake oil circuit outlet are connected, and the clutch oil circuit inlet and the clutch oil circuit outlet are disconnected.

[0010] When the input speed of the oil pump is less than the set value n2, the shift valve core, under the action of the shift spring, presses against one end of the valve core cavity, and the oil circuit switching valve shifts from the brake position to the clutch position. At this time, the clutch oil circuit inlet and outlet are connected, while the brake oil circuit inlet and outlet are disconnected. Thus, through the combined action of the shift spring and the oil pressure at the pump outlet on the shift valve core, when the input speed of the oil pump is greater than or equal to the set value n1, the corresponding oil pressure at the pump outlet will increase to the set value, thereby overcoming the force of the shift spring and shifting the oil circuit switching valve from the clutch position to the brake position, connecting the brake oil circuit inlet and outlet (i.e., brake circuit connected) and disconnecting the clutch oil circuit inlet and outlet (i.e., clutch circuit disconnected). When the input speed of the oil pump is less than the set value, the corresponding oil pressure at the pump outlet will decrease to the set value, and the shift valve core, under the action of the shift spring, presses against one end of the valve core cavity, and the oil... The circuit switching valve switches from the braking position to the clutch position, connecting the clutch oil circuit inlet and outlet (i.e., the clutch oil circuit is connected) and disconnecting the brake oil circuit inlet and outlet (i.e., the brake oil circuit is disconnected). This automatic switching between the clutch and brake oil circuits is achieved through mechanical structure automatic control and adjustment, effectively improving the reliability and stability of the hydraulic system's circuit switching control. It does not require control program intervention and avoids the problem in existing engineering vehicle hydraulic systems where a failure in any component of the solenoid valve, sensor, or controller can lead to the failure of the circuit switching function.

[0011] Preferably, the shift valve core includes a first piston, a second piston, and a third piston, which are sequentially distributed from one end of the valve core cavity to the other end. When the shift valve core is pressed against one end of the valve core cavity by the shift spring, the clutch oil circuit inlet and clutch oil circuit outlet are located between the first piston and the second piston, and one of the brake oil circuit inlet and brake oil circuit outlet is located between the second piston and the third piston, while the other is located between the third piston and the other end of the valve core cavity.

[0012] Preferably, when the shift valve core is pressed against the other end of the valve core cavity, the brake oil circuit inlet and brake oil circuit outlet are located between the second piston and the third piston, one of the clutch oil circuit inlet and clutch oil circuit outlet is located between the first piston and the second piston, and the other is closed by the first piston or located between the first piston and one end of the valve core cavity.

[0013] Preferably, a removable sealing plug is provided at one end of the valve core cavity.

[0014] Preferably, a protrusion is provided on the end of the shift valve core facing away from the shift spring. This ensures that the oil pressure at the pump outlet can smoothly pass through the shift oil circuit and act on the shift valve core.

[0015] Preferably, the oil pump includes a pump body, and the pump body and valve body are integrally formed. This helps to improve the structural compactness of the pump-valve assembly.

[0016] Preferably, the oil pump is a cycloidal pump, comprising an inner rotor and an outer rotor that mesh and drive each other, and a drive shaft for rotating the inner rotor. The tooth profile of the outer rotor, from tooth tip to tooth root, includes segments AB, BC, CD, DE, EF, and FG. The tooth profile of the inner rotor, from tooth tip to tooth root, includes segments ab, bc, cd, de, ef, and fg. Only segment CD of the outer rotor's tooth profile is a meshing transmission segment; the remaining segments AB, BC, DE, EF, and FG are hydraulic sealing segments. Only the corresponding segment cd of the inner rotor's tooth profile is a meshing transmission segment. The meshing transmission section is the main section. The remaining sections ab, bc, de, ef, and fg are hydraulically sealed sections. Among them, section de is the short-amplitude epicycloid of section CD; section bc is the inner equidistant offset line of the long-amplitude epicycloid of section BC; section ef is the equidistant offset line of section BC; section fg is the equidistant offset line of section AB; section ab is the intersection transition rounded line of section bc and the mirror line; section cd is the intersection transition rounded line of section de and section bc; section AB is the outer equidistant offset line of the long-amplitude incycloid of section ab; section DE is the equidistant offset line of section cd; section EF is the equidistant offset line of section bc; and section FG is the equidistant offset line of section ab.

[0017] In traditional cycloidal pumps, all teeth of the cycloidal rotor are in a meshing state, resulting in high tooth surface slippage and significant heat generation, especially in high-speed applications and with large-diameter rotors. To address this issue, this solution modifies the tooth profiles of the inner and outer rotors of the cycloidal pump, separating the transmission and sealing functions. Only the meshing transmission section maintains contact, while the other sections remain non-contacting, avoiding unnecessary tooth profile contact. This results in a large output oil volume, high transmission overlap, stable pressure output, reduced tooth surface slippage, heat generation, and noise, making it suitable for high-speed operation.

[0018] Preferably, the drive shaft is supported by a combination of deep groove ball bearings and needle roller bearings. This allows it to withstand the radial load generated by the input power, enabling smooth operation under complex and harsh working conditions and improving the reliability of pump operation.

[0019] Preferably, the inner and outer rotors adopt a one-tooth differential cycloidal structure. This helps to improve the compactness of the pump structure and ensures stable and reliable output.

[0020] The beneficial effects of this invention are: automatic switching between clutch and brake circuits is achieved through automatic control and adjustment of the mechanical structure, thereby effectively improving the reliability and stability of hydraulic system circuit switching control. Attached Figure Description

[0021] Figure 1 This is a cross-sectional structural diagram of the oil pump section of a pump-valve combination device applied to the hydraulic system of an engineering vehicle according to the present invention.

[0022] Figure 2 This is a cross-sectional structural diagram of the oil circuit switching valve of a pump-valve combination device applied to the hydraulic system of an engineering vehicle according to the present invention.

[0023] Figure 3 This is a top view of a pump and valve assembly device applied to the hydraulic system of an engineering vehicle according to the present invention.

[0024] Figure 4 This is a front view of the inner and outer rotors of an oil pump used in the hydraulic system of an engineering vehicle according to the present invention.

[0025] Figure 5 yes Figure 4 A magnified view of a portion of point A in the middle.

[0026] In the picture:

[0027] Oil pump 1, pump body 1.1, pump cover 1.2, inner rotor 1.3, outer rotor 1.4, drive shaft 1.5;

[0028] 2. Oil circuit switching valve, 2.1. Valve body, 2.2. Valve cover, 2.3. Valve core cavity, 2.4. Shift valve core, 2.41. First piston, 2.42. Second piston, 2.43. Third piston, 2.44. Protrusion, 2.45. Shift spring, 2.6. Sealing plug, 2.7. Clutch oil circuit inlet, 2.8. Clutch oil circuit outlet, 2.9. Brake oil circuit inlet, 2.10. Brake oil circuit outlet, 2.11. Connector;

[0029] Shift oil circuit 3. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0031] Specific Implementation Example 1, such as Figure 1 , Figure 2 , Figure 3 As shown, a pump-valve assembly for use in the hydraulic system of an engineering vehicle includes an oil pump 1 and an oil circuit switching valve 2. The oil pump is used to supply lubricating oil to the gearbox, and the oil pump includes an oil inlet and an oil outlet.

[0032] The hydraulic circuit switching valve 2 is used to control the on / off state of the clutch and brake hydraulic circuits of the engineering vehicle. The hydraulic circuit switching valve includes a valve body 2.1, a valve core cavity 2.3 housed within the valve body, a shift valve core 2.4 slidably mounted within the valve core cavity, and a shift spring 2.5 housed within the valve core cavity. The pump outlet is connected to one end of the valve core cavity via a shift hydraulic circuit 3. One end of the shift spring 2.5 rests against the other end of the valve core cavity, and the other end rests against the shift valve core 2.4. The valve body is equipped with a clutch hydraulic circuit inlet 2.7, a clutch hydraulic circuit outlet 2.8, a brake hydraulic circuit inlet 2.9, and a brake hydraulic circuit outlet 2.10. All four outlets (clutch, brake, and brake) are connected to the valve core cavity. In practical applications, the hydraulic circuit switching valve is installed in both the clutch and brake hydraulic circuits. Specifically, the clutch hydraulic circuit inlet and outlet of the switching valve are connected to the clutch hydraulic circuit to control its on / off state (when the clutch hydraulic circuit inlet and outlet are disconnected, the clutch hydraulic circuit is disconnected; when the clutch hydraulic circuit inlet and outlet are connected, the clutch hydraulic circuit is connected). The brake hydraulic circuit inlet and outlet of the switching valve are also connected to the clutch hydraulic circuit to control its on / off state (when the brake hydraulic circuit inlet and outlet are disconnected, the brake hydraulic circuit is disconnected; when the brake hydraulic circuit inlet and outlet are connected, the brake hydraulic circuit is connected).

[0033] The hydraulic circuit switching valve includes brake and clutch positions. When the input speed of the hydraulic pump is greater than or equal to the set value n1, the hydraulic pressure exerted by the hydraulic pump through the pump outlet and the shifting hydraulic circuit on the shifting valve core will overcome the force of the shifting spring, causing the hydraulic circuit switching valve to switch from the clutch position to the brake position. At this time, the brake hydraulic circuit inlet and outlet are connected, while the clutch hydraulic circuit inlet and outlet are disconnected.

[0034] When the input speed of the oil pump is less than the set value n2, the shift valve core, under the action of the shift spring, presses against one end of the valve core cavity, and the oil circuit switching valve shifts from the braking position to the clutch position. At this time, the clutch oil circuit inlet and outlet are connected, while the brake oil circuit inlet and outlet are disconnected. The set value n2 is less than the set value n1. In this embodiment, the set value n1 is 1000 r / min, and the set value n2 is 800, 850, or 900 r / min.

[0035] When the hydraulic system of the engineering vehicle using the pump-valve combination device of this embodiment is in operation,

[0036] The oil pump is powered by the vehicle's engine, which transmits power to the pump's drive shaft via a transmission mechanism. The oil pump supplies lubricating oil to the transmission; its outlet is connected to the transmission via an oil pipe. The oil circuit switching valve, through a shift spring and the oil pressure at the pump's outlet, acts on the shift valve core. When the pump's input speed is greater than or equal to a set value n1, the corresponding oil pressure at the outlet increases to the set value, overcoming the shift spring's force and shifting the oil circuit switching valve from the clutch position to the brake position. This connects the brake fluid inlet and outlet (brake circuit connected) and disconnects the clutch fluid inlet and outlet (clutch circuit disconnected). When the pump's input speed is less than the set value, the corresponding oil pressure at the outlet decreases to the set value, and the shift valve core, under the action of the shift spring, presses against one end of the valve core cavity. The hydraulic circuit switching valve switches from the brake position to the clutch position, connecting the clutch oil circuit inlet and outlet (i.e., the clutch oil circuit is connected) and disconnecting the brake oil circuit inlet and outlet (i.e., the brake oil circuit is disconnected). This automatic switching between the clutch and brake oil circuits is achieved through mechanical structure automatic control and adjustment, effectively improving the reliability and stability of the hydraulic system's oil circuit switching control. It does not require control software and avoids the problem in existing engineering vehicle hydraulic systems where a failure in any component of the solenoid valve, sensor, or controller can lead to the failure of the oil circuit switching function.

[0037] Specifically, such as Figure 2 As shown, the shift valve core 2.4 includes a first piston 2.41, a second piston 2.42, and a third piston 2.43. The first, second, and third pistons are sequentially distributed from one end of the valve core cavity to the other end. When the shift valve core is pressed against one end of the valve core cavity by the shift spring, the clutch oil circuit inlet and clutch oil circuit outlet are located between the first and second pistons; one of the brake oil circuit inlet and brake oil circuit outlet is located between the second and third pistons, and the other is located between the third piston and the other end of the valve core cavity (for example, the brake oil circuit inlet is located between the second and third pistons, and the brake oil circuit outlet is located between the third piston and the other end of the valve core cavity). At this time, the clutch oil circuit inlet and clutch oil circuit outlet are connected, and the brake oil circuit inlet and brake oil circuit outlet are disconnected.

[0038] When the shift valve core is pressed against the other end of the valve core cavity, the brake fluid inlet and brake fluid outlet are located between the second and third pistons; one of the clutch fluid inlet and clutch fluid outlet is located between the first and second pistons, and the other is either closed by the first piston or located between the first piston and one end of the valve core cavity (for example, the clutch fluid inlet is located between the first and second pistons, and the clutch fluid outlet is closed by the first piston). At this time, the clutch fluid inlet and clutch fluid outlet are disconnected, and the brake fluid inlet and brake fluid outlet are connected.

[0039] Furthermore, such as Figure 1 , Figure 2 , Figure 3 As shown, the oil pump 1 also includes a pump body 1.1 and a pump cover 1.2, which are bolted together. The oil circuit switching valve 2 also includes a valve cover 2.2, which is bolted together with the valve body. The pump body and valve body are integrally formed. This design helps to improve the compactness of the pump-valve assembly.

[0040] In this embodiment, the clutch oil circuit inlet, clutch oil circuit outlet, brake oil circuit inlet, and brake oil circuit outlet of the oil circuit switching valve are all provided with connectors 2.11 for connecting the corresponding oil circuit pipes; and the connectors are provided on the valve cover.

[0041] Furthermore, such as Figure 2 As shown, a removable sealing plug 2.6 is provided on one end of the valve core cavity.

[0042] Furthermore, a protrusion 2.44 is provided on the end of the shift valve core facing away from the shift spring. In this embodiment, the shift valve core abuts against the sealing plug at one end of the valve core cavity via the protrusion. This ensures that the oil pressure at the pump outlet can smoothly act on the shift valve core through the shift oil passage.

[0043] In this second specific embodiment, the remaining structure is the same as in the first specific embodiment, except that...

[0044] like Figure 1 , Figure 4 , Figure 5 As shown, the oil pump is a cycloidal pump. The oil pump 1 includes an inner rotor 1.3 and an outer rotor 1.4 that mesh with each other, and a drive shaft 1.5 for driving the inner rotor to rotate.

[0045] The tooth profile of the outer rotor, from tooth tip to tooth root, includes segments AB, BC, CD, DE, EF, and FG. The tooth profile of the inner rotor, from tooth tip to tooth root, includes segments ab, bc, cd, de, ef, and fg. In the outer rotor's tooth profile, only segment CD is the meshing transmission segment; the remaining segments AB, BC, DE, EF, and FG are hydraulically sealed segments. These hydraulically sealed segments do not participate in the transmission; they only provide oil sealing for the rotor pair. Similarly, in the inner rotor's tooth profile, only segment cd is the meshing transmission segment; the remaining segments ab, bc, de, ef, and fg are hydraulically sealed segments. These hydraulically sealed segments do not participate in the transmission; they only provide oil sealing for the rotor pair. In the tooth profile curves of the outer and inner rotors, segment CD (corresponding to segment cd of the inner rotor) is a cycloidal segment, the same as the conventional cycloidal segment (i.e. the same as the cycloidal segment of the outer rotor of the existing cycloidal pump), segment de is the short-amplitude epicycloidal segment of segment CD, segment bc is the inner equidistant offset line of the long-amplitude epicycloidal segment BC, segment ef is the equidistant offset line of segment BC, segment fg is the equidistant offset line of segment AB, segment ab is the intersection transition rounding of segment bc and the mirror line, segment cd is the intersection transition rounding of segment de and segment bc, segment AB is the outer equidistant offset line of the long-amplitude inner cycloidal segment ab, segment DE is the equidistant offset line of segment cd, segment EF is the equidistant offset line of segment bc, and segment FG is the equidistant offset line of segment ab.

[0046] In traditional cycloidal pumps, all teeth of the cycloidal rotor are in a meshing state, resulting in high tooth surface slippage and significant heat generation, especially in high-speed applications and with large-diameter rotors. To address this issue, this solution modifies the tooth profiles of the inner and outer rotors of the cycloidal pump, separating the transmission and sealing functions. Only the meshing transmission section maintains contact, while the other sections remain non-contacting, avoiding unnecessary tooth profile contact. This results in a large output oil volume, high transmission overlap, stable pressure output, reduced tooth surface slippage, heat generation, and noise, making it suitable for high-speed operation.

[0047] The drive shaft is supported by a combination of deep groove ball bearings and needle roller bearings. This allows it to withstand the radial load generated by the input power, enabling it to operate smoothly under complex and harsh conditions and improving the reliability of pump operation.

[0048] The inner and outer rotors adopt a one-tooth differential cycloidal structure. This helps to improve the compactness of the pump structure and ensures stable and reliable output.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A pump and valve assembly for use in the hydraulic system of an engineering vehicle, comprising: The oil pump supplies lubricating oil to the transmission, including the pump inlet and pump outlet. The hydraulic circuit switching valve controls the on / off state of the clutch and brake hydraulic circuits of the engineering vehicle; its characteristic is that... The oil circuit switching valve includes a valve body, a valve core cavity disposed within the valve body, a shift valve core slidably disposed within the valve core cavity, and a shift spring disposed within the valve core cavity. The valve body is provided with a clutch oil circuit inlet, a clutch oil circuit outlet, a brake oil circuit inlet, and a brake oil circuit outlet. The pump outlet is connected to one end of the valve core cavity through a shift oil circuit. One end of the shift spring abuts against the other end of the valve core cavity, and the other end of the shift spring abuts against the shift valve core. The shift valve core includes a first piston, a second piston, and a third piston that are sequentially distributed from one end of the valve core cavity to the other end. When the shift valve core is pressed against one end of the valve core cavity by the shift spring, the clutch oil circuit inlet and clutch oil circuit outlet are located between the first piston and the second piston, and one of the brake oil circuit inlet and brake oil circuit outlet is located between the second piston and the third piston, while the other is located between the third piston and the other end of the valve core cavity.

2. The pump and valve assembly for use in the hydraulic system of an engineering vehicle according to claim 1, characterized in that, The oil circuit switching valve includes a brake position and a clutch position. When the input speed of the oil pump is greater than or equal to the set value n1, the oil pressure exerted by the oil pump on the shift valve core through the pump outlet and the shift oil circuit will overcome the force of the shift spring, causing the oil circuit switching valve to switch from the clutch position to the brake position. At this time, the brake oil circuit inlet and the brake oil circuit outlet are connected, and the clutch oil circuit inlet and the clutch oil circuit outlet are disconnected. When the input speed of the oil pump is less than the set value n2, the shift valve core is pressed against one end of the valve core cavity under the action of the shift spring, and the oil circuit switching valve shifts from the brake position to the clutch position. At this time, the clutch oil circuit inlet and clutch oil circuit outlet are connected, and the brake oil circuit inlet and brake oil circuit outlet are disconnected.

3. A pump and valve assembly for use in a hydraulic system of an engineering vehicle according to claim 1 or 2, characterized in that, When the shift valve core is pressed against the other end of the valve core cavity, the brake oil circuit inlet and brake oil circuit outlet are located between the second piston and the third piston, one of the clutch oil circuit inlet and clutch oil circuit outlet is located between the first piston and the second piston, and the other is closed by the first piston or located between the first piston and one end of the valve core cavity.

4. A pump and valve assembly for use in a hydraulic system of an engineering vehicle according to claim 1 or 2, characterized in that, A removable sealing plug is provided at one end of the valve core cavity.

5. A pump and valve assembly for use in a hydraulic system of an engineering vehicle according to claim 1 or 2, characterized in that, The shift valve core has a protrusion on the end facing away from the shift spring.

6. A pump-valve assembly for use in a hydraulic system of an engineering vehicle according to claim 1 or 2, characterized in that, The oil pump includes a pump body, and the pump body and valve body are integrally formed.

7. A pump and valve assembly for use in a hydraulic system of an engineering vehicle according to claim 1 or 2, characterized in that, The oil pump is a cycloidal pump, comprising an inner rotor and an outer rotor that mesh and drive each other, and a drive shaft for rotating the inner rotor. The tooth profile of the outer rotor, from tooth tip to tooth root, includes segments AB, BC, CD, DE, EF, and FG. The tooth profile of the inner rotor, from tooth tip to tooth root, includes segments ab, bc, cd, de, ef, and fg. Only segment CD of the outer rotor's tooth profile is a meshing transmission segment; the remaining segments AB, BC, DE, EF, and FG are hydraulic sealing segments. Only the corresponding segment cd of the inner rotor's tooth profile is a meshing transmission segment. The transmission section is complete. The remaining sections ab, bc, de, ef, and fg are hydraulically sealed sections. Among them, section de is the short-amplitude epicycloid of section CD; section bc is the inner equidistant offset line of the long-amplitude epicycloid of section BC; section ef is the equidistant offset line of section BC; section fg is the equidistant offset line of section AB; section ab is the intersection transition rounded line of section bc and the mirror line; section cd is the intersection transition rounded line of section de and section bc; section AB is the outer equidistant offset line of the long-amplitude incycloid of section ab; section DE is the equidistant offset line of section cd; section EF is the equidistant offset line of section bc; and section FG is the equidistant offset line of section ab.

8. A pump and valve assembly for use in a hydraulic system of an engineering vehicle according to claim 7, characterized in that, The drive shaft is supported by a combination of deep groove ball bearings and needle roller bearings.

9. A pump and valve assembly for use in a hydraulic system of an engineering vehicle according to claim 7, characterized in that, The inner rotor and outer rotor adopt a one-tooth differential cycloidal structure.

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