A vdc hydraulic pump

Abstract

The application relates to a VDC hydraulic pump which comprises a pump body, a gear box body arranged on the pump body, a driving motor connected with the gear box body, a valve body arranged on the pump body, an oil path arranged in the valve body, the oil path being connected with an external oil supply source and the driving motor, a pressure relief module connected with the oil path and arranged on the pump body, an oil outlet valve block connected with the gear box body and arranged on the pump body, and a sensing module arranged on the pump body. The external oil supply source is used for feeding oil, the oil is delivered to the driving motor through the oil path, the driving motor is driven to rotate and drive the gear of the gear box body, the oil is discharged through the oil outlet valve block, the sensing module detects the liquid level of the pump body, and the pressure relief module is used for relieving the pressure of the oil path and the driving motor. The application has the effects of reducing the problem of excessive system pressure and prolonging the expected service life of the pump body.

Description

Technical Field

[0001] This application relates to the field of hydraulic transmission technology, and in particular to a VDC hydraulic pump. Background Technology

[0002] Hydraulic pumps, as core components of hydraulic systems, are widely used in fields such as engineering machinery, aerospace, and shipbuilding. In recent years, with the development of industrial automation and intelligence, higher requirements have been placed on the efficiency, reliability, and energy-saving performance of hydraulic pumps.

[0003] Currently, the most common hydraulic pumps on the market are gear pumps. Gear pumps are one of the most common positive displacement pumps in hydraulic systems. Their working process is as follows: when the gears disengage, the volume between the teeth increases, creating a partial vacuum in the suction chamber. The oil in the tank is drawn into the space between the teeth under atmospheric pressure through the suction port. The drawn-in oil is enveloped by the gears and transported along the inner wall of the pump casing to the pressure chamber. At this time, the gear meshing point isolates the suction chamber from the pressure chamber. When the gears engage, the volume between the teeth decreases, the oil is squeezed, the pressure increases, and the one-way valve at the outlet is opened, allowing the high-pressure oil to be discharged from the pressure port to the system pipeline.

[0004] Gear pumps have a simple structure, low cost, and strong anti-pollution ability, but their radial force and end face leakage limit their high pressure performance and pressure resistance. They also have a short service life under high pressure and high flow conditions. Utility Model Content

[0005] To address the short lifespan of gear pumps under high pressure and high flow conditions, this application provides a VDC hydraulic pump.

[0006] The VDC hydraulic pump provided in this application adopts the following technical solution:

[0007] A VDC hydraulic pump includes a pump body, a gearbox and a drive motor mounted on the pump body, the rotating shaft of the drive motor being connected to a gear in the gearbox, the gearbox being used to deliver hydraulic oil from the pump body, a valve body on the pump body, an oil passage for transporting drive oil inside the valve body being provided, the oil passage being connected to an external oil supply source and the drive motor, a pressure relief module on the pump body connected to the oil passage for relieving pressure in the oil passage, an oil outlet valve block on the pump body for discharging oil being connected to the gearbox, and a sensing module on the pump body for detecting the pump body's liquid level.

[0008] By adopting the above technical solution, oil is supplied from an external oil source and transported to the drive motor through the oil circuit. The drive motor then drives the gearbox gears, and the oil is discharged through the oil outlet valve block. The sensing module detects the pump body liquid level, and the pressure relief module relieves pressure on the oil circuit and drive motor, reducing the problem of excessive system pressure and extending the expected service life of the pump body.

[0009] Optionally, the oil circuit includes a first oil circuit and a second oil circuit disposed in the valve body and interconnected with each other. The valve body is provided with a drive oil port for oil inlet and a return oil port for oil return. One end of the first oil circuit is connected to the drive oil port, the second oil circuit is connected to the drive motor, and the second oil circuit is connected to the pressure relief module.

[0010] By adopting the above technical solution, the drive oil is introduced into the first oil circuit through the drive oil port, and then transported to the second oil circuit through the first oil circuit. The second oil circuit provides power to the drive motor. The second oil circuit is connected to the pressure relief module to relieve pressure in the oil circuit. The interconnected first and second oil circuits allow the hydraulic oil to be transported smoothly in the valve body, ensuring the stable operation of the hydraulic drive components and drive motor.

[0011] Optionally, the valve body is provided with a solenoid valve connected to the first oil circuit, one side of the solenoid valve is connected to the second oil circuit, and a throttle valve for adjusting the driving oil flow of the second oil circuit is provided on the second oil circuit.

[0012] By adopting the above technical solution, the solenoid valve is connected to the first oil circuit. When the solenoid valve is de-energized, the oil circuit is blocked, controlling the opening and closing of the oil circuit to achieve precise control of the flow of driving oil. A throttle valve is set on the second oil circuit to adjust the flow rate of driving oil and meet the flow requirements of different working scenarios.

[0013] Optionally, the drive motor is connected to the return port of the valve body via a return oil pipe, the second oil circuit is connected to the return oil pipe via a return oil circuit, and the valve body is provided with an overflow valve, which is connected to the return oil circuit.

[0014] By adopting the above technical solution, the return oil pipe and return oil circuit can allow the drive oil to flow back to form an oil circuit. The overflow valve regulates the pressure of the return oil circuit to ensure stable oil circuit pressure and reduce the problem of excessive pressure damaging drive motor components.

[0015] Optionally, the pressure relief module includes a pressure relief valve and a third oil circuit. The pressure relief valve is located on the upper side of the oil outlet valve block, and the third oil circuit is located on the pressure relief valve and connected to the second oil circuit.

[0016] By adopting the above technical solution, the driving oil is transported to the third oil circuit via the second oil circuit, and then to the pressure relief valve via the third oil circuit to relieve pressure in the oil circuit, thus ensuring the safe operation of the hydraulic pump.

[0017] Optionally, a support base is provided on the top of the pump body, and an oil delivery pipe is provided inside the pump body, coaxially distributed with the pump body. The oil outlet valve block is provided with an oil outlet path for oil delivery and an oil guide pipe for oil return. The oil guide pipe is connected to the oil outlet path, and the oil guide pipe and the oil outlet path are connected to the oil delivery pipe. A lifting plate is slidably installed on the pump body, and the lifting plate is slidably connected to the oil delivery pipe. An oil delivery mechanism for feeding oil into the oil delivery pipe is provided on one side of the support base.

[0018] By adopting the above technical solution, the hydraulic oil in the pump body is delivered through the oil supply pipe and the oil outlet. The lifting plate rises and falls with the change of hydraulic oil level in the pump body. The oil guide pipe is connected to the oil outlet to realize oil return. Oil is fed into the oil supply pipe through the oil supply mechanism to ensure the normal operation of the pump body.

[0019] Optionally, the pressure relief valve includes a cylinder, the third oil passage is connected to the top of the cylinder, a drive piston is slidably installed inside the cylinder, a fixed seat is connected to the lower side of the drive piston, a one-way valve seat is provided on the lower side of the fixed seat, a return oil groove is provided on the cylinder at the fixed seat, the return oil groove is connected to the oil guide pipe, and a return oil branch is provided on the oil outlet valve block, which is connected to the oil outlet passage and the return oil groove, and the one-way valve seat closes the return oil branch.

[0020] By adopting the above technical solution, when the driving oil is delivered to the cylinder barrel through the third oil circuit to release pressure, it pushes the driving piston to move the one-way valve seat to close the return oil branch. When the work stops, the driving oil returns after the third oil circuit is depressurized, and the driving piston moves the one-way valve seat to separate from the return oil branch. At this time, the return oil branch is connected to the return oil groove, and the hydraulic oil returns to the return oil branch through the oil outlet, and then is delivered to the oil guide pipe through the return oil groove and returned to the oil delivery pipe, ensuring the safe and stable operation of the system.

[0021] Optionally, the pump body is provided with a pressure switch connected to the oil outlet, and a connection socket for electrical connection with external information equipment is provided on one side of the pressure switch.

[0022] By adopting the above technical solution, the pressure switch detects the oil circuit pressure, and the connection socket electrically connects the pressure switch to the external information device, which facilitates the transmission of the oil circuit pressure information to the external information device.

[0023] Optionally, the oil delivery mechanism includes a refueling pipe and a plug. The refueling pipe is mounted on the support and connected to the oil delivery pipe. The plug is fitted onto the end of the refueling pipe opposite to the oil delivery pipe and blocks the oil delivery pipe. A high-level valve body is mounted on the support and located at the refueling pipe. A force-bearing rod is slidably mounted on the high-level valve body in the vertical direction. When the lifting plate slides to the top of the pump body, one end of the force-bearing rod abuts against one side of the lifting plate. A force-bearing spring is fitted on the force-bearing rod and connected to the high-level valve body. An indicator rod is mounted on the top of the force-bearing rod and located outside the high-level valve body.

[0024] By adopting the above technical solution, the oil filling pipe and the plug can be used to control the oil inlet and blockage of the oil delivery pipe. When oil is added to the pump body through the oil delivery pipe, the lifting plate slides to the top of the pump body and abuts against the lifting plate through the force rod, and pushes out the indicator rod to give a high liquid level indication signal, so as to make it easy to grasp the liquid level of the pump body.

[0025] Optionally, the sensing module includes an ultrasonic sensor disposed on the top of the pump body, with one end of the ultrasonic sensor probe located inside the pump body and vertically downward, and the ultrasonic sensor is used to collect the high and low liquid level signals of the lifting plate.

[0026] By adopting the above technical solution, one end of the ultrasonic sensor probe collects the high and low liquid level signals of the lifting plate, thereby realizing the real-time monitoring of the liquid level in the pump body.

[0027] In summary, this application includes at least one of the following beneficial technical effects:

[0028] 1. By setting up a pressure relief module to relieve pressure on the hydraulic drive components, excessive pressure in the pump body can be avoided, the problem of limited pressure resistance of gear pumps can be solved, and the service life of the pump body under high pressure conditions can be improved.

[0029] 2. A throttle valve is installed on the second oil circuit to adjust the flow of drive oil, which can adjust the operation of the drive motor according to the actual working conditions and improve the efficiency of the hydraulic pump;

[0030] 3. Ultrasonic sensors detect the liquid level in the pump body, facilitating timely understanding of the pump's operating status and improving the reliability of the hydraulic pump. Attached Figure Description

[0031] Figure 1 This is a three-dimensional structural diagram of this application.

[0032] Figure 2 This is a three-dimensional structural diagram of one side of the pressure relief module of this application.

[0033] Figure 3 This is a partial cross-sectional structural diagram of the valve body of this application, mainly used to illustrate the oil circuit.

[0034] Figure 4 This is a cross-sectional view of the support base and the inner part of the pump body in this application.

[0035] Figure 5 This is a cross-sectional view of the cylinder barrel and the oil outlet valve block of this application.

[0036] Figure 6 This is a cross-sectional structural diagram of the internal parts of the cylinder barrel and the oil outlet valve block of this application.

[0037] Figure 7 This is an enlarged sectional view of Part A of this application.

[0038] Those skilled in the art will understand that the elements in the accompanying drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the size and position of some elements in the drawings may be enlarged relative to other elements to aid in understanding the embodiments of the invention.

[0039] Attached reference numerals: 1. Pump body; 11. Support base; 111. High-level valve body; 112. Force rod; 113. Force spring; 114. Indicator rod; 12. Oil delivery pipe; 13. Lifting plate; 14. Pressure switch; 15. Connecting socket; 2. Gearbox body; 3. Drive motor; 4. Valve body; 41. Oil circuit; 411. First oil circuit; 412. Second oil circuit; 42. Drive oil port; 43. Return oil port; 44. Solenoid valve; 45. Drive oil pressure gauge; 46. Throttle valve; 47. 48. Return oil pipe; 49. Return oil circuit; 50. Overflow valve; 61. Pressure relief module; 52. Pressure relief valve; 53. Third oil circuit; 511. Cylinder barrel; 512. Drive piston; 513. Fixed seat; 514. One-way valve seat; 515. Return oil groove; 61. Oil outlet valve block; 62. Oil outlet circuit; 63. Guide oil pipe; 64. Limit ball; 65. Limit spring; 66. Oil outlet pressure gauge; 67. Return oil branch; 88. Ultrasonic sensor; 9. Oil delivery mechanism; 10. Filling pipe; 11. Plug. Detailed Implementation

[0040] The present application will be further described in detail below with reference to the accompanying drawings.

[0041] This application discloses a VDC hydraulic pump, referring to... Figure 1 and Figure 2The system includes a pump body 1, a gearbox 2, a drive motor 3, a valve body 4, a pressure relief module 5, an oil outlet valve block 6, and a sensing module. The pump body 1 houses the gearbox 2 and the drive motor 3. The rotating shaft of the drive motor 3 is connected to the gears in the gearbox 2. The gearbox 2 is used to deliver hydraulic oil from inside the pump body 1. The valve body 4 has an oil passage 41 for transporting drive oil, which is connected to an external oil supply source and the drive motor 3. The pressure relief module 5 on the pump body 1 is connected to the oil passage 41 to relieve pressure. The oil outlet valve block 6 is connected to the gearbox 2 for oil discharge. The sensing module is located on the pump body 1 to detect the liquid level. After the external oil supply source provides oil, the drive motor 3 operates through the oil passage 41, driving the gears to discharge oil. Simultaneously, the sensing module detects the liquid level, and the pressure relief module 5 ensures stable pressure in the oil passage 41, thus reducing the problem of excessive system pressure and extending the expected service life of the pump body 1.

[0042] Reference Figure 3 The valve body 4 is equipped with a drive port 42 and a return port 43. Both the drive port 42 and the return port 43 are connected to an external oil supply pipe via pipe fittings. The oil circuit 41 includes a first oil circuit 411 and a second oil circuit 412, which are located within the valve body 4 and interconnected. One end of the first oil circuit 411 is connected to the drive port 42, and the second oil circuit 412 is connected to the drive motor 3 and the pressure relief module 5. The interconnected first oil circuit 411 and second oil circuit 412 ensure smooth hydraulic oil transport within the valve body 4, guaranteeing stable operation of the hydraulic drive components and the drive motor 3.

[0043] Reference Figure 3 The valve body 4 is equipped with a solenoid valve 44 connected to the first oil passage 411. One side of the solenoid valve 44 is connected to the second oil passage 412, and a drive oil pressure gauge 45 is installed on one side of the solenoid valve 44. A throttle valve 46 is installed on the second oil passage 412. The solenoid valve 44 is connected to the first oil passage 411. When the solenoid valve 44 is de-energized, the oil passage 41 is closed, controlling the opening and closing of the oil passage 41 to achieve precise control of the drive oil flow. The throttle valve 46 on the second oil passage 412 regulates the drive oil flow rate.

[0044] Reference Figure 3 The drive motor 3 is connected to the return port 43 of the valve body 4 via the return oil pipe 47. The second oil circuit 412 is connected to the return oil pipe 47 via the return oil circuit 48. The valve body 4 is equipped with an overflow valve 49, which is connected to the return oil circuit 48. The return oil pipe 47 and the return oil circuit 48 allow the drive oil to flow back to form the oil circuit 41. The overflow valve 49 regulates the pressure of the return oil circuit 48 to ensure the pressure of the oil circuit 41 is stable.

[0045] Reference Figure 4 , Figure 5 and Figure 6A support base 11 is provided on the top of the pump body 1. An oil delivery pipe 12 is coaxially distributed within the pump body 1. An oil outlet valve block 6 is provided with an oil outlet passage 61 for oil delivery and an oil return guide pipe 62 for oil return. The oil return guide pipe 62 is connected to the oil outlet passage 61. An oil outlet pressure gauge 63 connected to the oil outlet passage 61 is provided on the oil outlet valve block 6. A limit ball 621 for blocking the oil outlet passage 61 and a limit spring 622 for pushing the limit ball 621 to a stop are provided. The oil return guide pipe 62... The pump body 1 is equipped with an oil outlet 61 connected to the oil supply pipe 12. A lifting plate 13 is vertically slidably installed inside the pump body 1. The lifting plate 13 is horizontally distributed, with an oil storage area on its lower side. The lifting plate 13 is slidably connected to the oil supply pipe 12. Hydraulic oil in the pump body 1 is transported through the oil supply pipe 12 and the oil outlet 61, pushing the limit ball 621 to move until the limit spring 622 is compressed, at which point oil is discharged. The lifting plate 13 rises and falls with the change in the hydraulic oil level in the pump body 1. The guide pipe 62 is connected to the oil outlet 61 to achieve oil return. A pressure switch 14 connected to the oil outlet 61 is provided on the pump body 1. A connection socket 15 for electrical connection to external information equipment is provided on one side of the pressure switch 14. The pressure switch 14 detects the pressure of the oil outlet 61, and the connection socket 15 electrically connects the pressure switch 14 to the external information equipment, facilitating the transmission of the oil outlet 61 pressure information to the external information equipment.

[0046] Reference Figure 7 An oil delivery mechanism 8 is provided on one side of the support base 11. The oil delivery mechanism 8 includes an oil filling pipe 81 and a plug 82. The oil filling pipe 81 is provided on the support base 11 and connected to the oil delivery pipe 12. The plug 82 is sleeved on the end of the oil filling pipe 81 away from the oil delivery pipe 12 and blocks the oil delivery pipe 12. The oil filling pipe 81 and the plug 82 work together to control the oil inlet and blockage of the oil delivery pipe 12.

[0047] Reference Figure 7A high-level valve body 111 is vertically installed on the support base 11 and located at the refueling pipe 81. The top of the high-level valve body 111 is located outside the support base 11, and the bottom is located inside the pump body 1. A force-bearing rod 112 is slidably installed inside the high-level valve body 111 along the vertical direction. The downward end of the force-bearing rod 112 passes through the high-level valve body 111 and is located outside the high-level valve body 111. When the lifting plate 13 slides to the top side inside the pump body 1, the downward end of the force-bearing rod 112... One end of the force rod 112 abuts against one side of the lifting plate 13. A force spring 113 is provided at the top of the force rod 112. The force spring 113 is connected to the high liquid level valve body 111. A contact sleeve that slides and connects to the high liquid level valve body 111 is provided at the top of the force spring 113. A vertical indicator rod 114 is provided on the upward side of the contact sleeve. The upward end of the indicator rod 114 is located outside the high liquid level valve seat. The indicator rod 114 is slidably connected to the high liquid level valve seat and is connected by a return spring. When oil is added to the pump body 1 through the oil supply pipe 12, the lifting plate 13 slides to the top of the inner side of the pump body 1. The force rod 112 abuts against the lifting plate 13, pushing out the indicator rod 114 to give a high liquid level indication signal, making it easy to monitor the liquid level of the pump body 1. The support base 11 is also equipped with an overflow valve 49 connected to the oil supply pipe 12. The overflow valve 49 is a one-way valve. When the internal pressure of the pump body 1 is abnormal and it is inconvenient to adjust it through the oil circuit 41, the pressure of the hydraulic oil is adjusted in time through the overflow valve 49.

[0048] Reference Figure 5 and Figure 6 The pressure relief module 5 includes a pressure relief valve 51 and a third oil passage 52. The pressure relief valve 51 is located on the upper side of the oil outlet valve block 6, and the third oil passage 52 is located on the pressure relief valve 51 and connected to the second oil passage 412.

[0049] Reference Figure 5 and Figure 6The pressure relief valve 51 includes a cylinder 511. The top of the cylinder 511 is connected to one end of the third oil passage 52. A drive piston 512 is slidably mounted inside the cylinder 511 in a vertical direction. The drive piston 512 is sealed with a rubber sealing ring to prevent drive oil leakage. A fixed seat 513 is connected to the lower side of the drive piston 512. A one-way valve seat 514 is provided on the lower side of the fixed seat 513. A return oil groove 515 is provided on the cylinder 511 at the fixed seat 513. The return oil groove 515 is connected to the oil guide pipe 62. A return oil branch 64 is provided on the oil outlet valve block 6, which is connected to the oil outlet passage 61 and the return oil groove 515. The one-way valve seat 514 closes the return oil branch 64 with its downward end facing down. The driving oil is delivered to the third oil passage 52 via the second oil passage 412, and then to the pressure relief valve 51 via the third oil passage 52. This valve pushes the driving piston 512 to move the one-way valve seat 514 to close the return oil branch 64. When the operation stops, the driving oil returns after the pressure is released in the third oil passage 52. The driving piston 512 moves the one-way valve seat 514 to separate from the return oil branch 64. At this time, the return oil branch 64 is connected to the return oil groove 515. The hydraulic oil returns to the return oil branch 64 via the oil outlet 61, and is delivered to the guide oil pipe 62 via the return oil groove 515, and then returns to the oil delivery pipe 12, ensuring the safe operation of the hydraulic pump.

[0050] Reference Figure 1 The sensing module includes an ultrasonic sensor 7, which is located on the top of the pump body 1. One end of its probe is located inside the pump body 1 and is vertically downward. The ultrasonic sensor 7 collects the high and low liquid level signals of the lifting plate 13 by emitting and receiving ultrasonic signals, so as to realize real-time monitoring of the liquid level of the pump body 1.

[0051] The implementation principle of a VDC hydraulic pump according to an embodiment of this application is as follows: An external oil source supplies oil, and driving oil enters the first oil circuit 411 from the driving oil port 42 of the valve body 4 and is transported to the second oil circuit 412. The second oil circuit 412 provides power to the drive motor 3. The drive motor 3 rotates, driving the gears of the gearbox 2 to rotate. The driving oil flows back to the return oil port 43 of the valve body 4 through the return oil pipe 47 and the return oil circuit 48, forming a complete oil circuit 41 circulation. Hydraulic oil inside the pump body 1 is drawn in from the suction port and then sent out through the pressure port via the outlet oil circuit 61 of the outlet valve block 6. The pressure switch 14 detects the pressure of the outlet oil circuit 61 and transmits the pressure information of the outlet oil circuit 61 to an external information device through the connection socket 15. When the pressure in the drive motor 3's oil circuit 41 is too high, the driving oil is transported through the second oil circuit 412 to the third oil circuit 52, and then through the third oil circuit 52 to the pressure relief valve 51, pushing the drive piston 512 to move the one-way valve seat 514 to relieve pressure, ensuring the safe operation of the hydraulic pump.

[0052] The ultrasonic sensor 7 of the sensing module collects the high and low liquid level signals of the lifting plate 13 in real time by transmitting and receiving ultrasonic signals, so as to realize real-time monitoring of the liquid level of the pump body 1 and take timely measures when the liquid level is abnormal.

[0053] When it is necessary to add oil to the pump body 1, oil is added through the oiling pipe 81. The lifting plate 13 is pushed and slid to the top of the inner side of the pump body 1. The lifting plate 13 is abutted by the force rod 112, and the indicator rod 114 is pushed out to give a high liquid level indication signal, so as to make it easy to grasp the liquid level of the pump body 1.

[0054] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A VDC hydraulic pump, comprising a pump body (1), wherein a gearbox (2) and a drive motor (3) are disposed on the pump body (1), the rotating shaft of the drive motor (3) is connected to a gear in the gearbox (2), and the gearbox (2) is used to deliver hydraulic oil from inside the pump body (1), characterized in that: The pump body (1) is provided with a valve body (4), and the valve body (4) is provided with an oil passage (41) for transporting driving oil. The oil passage (41) is connected to an external oil supply source and is connected to the drive motor (3). The pump body (1) is provided with a pressure relief module (5) connected to the oil passage (41). The pressure relief module (5) is used to relieve pressure on the oil passage (41). The pump body (1) is provided with an oil outlet valve block (6) for discharging oil. The oil outlet valve block (6) is connected to the gearbox body (2). The pump body (1) is provided with a sensing module for detecting the liquid level of the pump body (1).

2. A VDC hydraulic pump according to claim 1, characterized in that: The oil passage (41) includes a first oil passage (411) and a second oil passage (412) disposed in the valve body (4) and interconnected with each other. The valve body (4) is provided with a drive oil port (42) for oil inlet and a return oil port (43) for oil return. One end of the first oil passage (411) is connected to the drive oil port (42), the second oil passage (412) is connected to the drive motor (3), and the second oil passage (412) is connected to the pressure relief module (5).

3. A VDC hydraulic pump according to claim 2, characterized in that: The valve body (4) is provided with a solenoid valve (44) connected to the first oil circuit (411). One side of the solenoid valve (44) is connected to the second oil circuit (412). The second oil circuit (412) is provided with a throttle valve (46) for adjusting the flow rate of the driving oil of the second oil circuit (412).

4. A VDC hydraulic pump according to claim 2, characterized in that: The drive motor (3) is connected to the return port (43) of the valve body (4) through the return oil pipe (47), the second oil circuit (412) is connected to the return oil pipe (47) through the return oil circuit (48), and the valve body (4) is provided with an overflow valve (49), which is connected to the return oil circuit (48).

5. A VDC hydraulic pump according to claim 2, characterized in that: The pressure relief module (5) includes a pressure relief valve (51) and a third oil passage (52). The pressure relief valve (51) is located on the upper side of the oil outlet valve block (6), and the third oil passage (52) is located on the pressure relief valve (51) and connected to the second oil passage (412).

6. A VDC hydraulic pump according to claim 5, characterized in that: The pump body (1) is provided with a support base (11) on top. The pump body (1) is provided with an oil delivery pipe (12) coaxially distributed with the pump body (1). The oil outlet valve block (6) is provided with an oil outlet path (61) for oil outlet and an oil guide pipe (62) for oil return. The oil guide pipe (62) is connected to the oil outlet path (61). The oil guide pipe (62) and the oil outlet path (61) are connected to the oil delivery pipe (12). The pump body (1) is slidably installed with a lifting plate (13). The lifting plate (13) is slidably connected to the oil delivery pipe (12). The support base (11) is provided with an oil delivery mechanism (8) for oil to enter the oil delivery pipe (12) on one side.

7. A VDC hydraulic pump according to claim 6, characterized in that: The pressure relief valve (51) includes a cylinder (511), the third oil passage (52) is connected to the top of the cylinder (511), a drive piston (512) is slidably installed inside the cylinder (511), a fixed seat (513) is connected to the lower side of the drive piston (512), a one-way valve seat (514) is provided on the lower side of the fixed seat (513), a return oil groove (515) is provided on the cylinder (511) at the fixed seat (513), the return oil groove (515) is connected to the oil guide pipe (62), and a return oil branch (64) is provided on the oil outlet valve block (6) that is connected to the oil outlet passage (61) and the return oil groove (515), and the one-way valve seat (514) closes the return oil branch (64).

8. A VDC hydraulic pump according to claim 6, characterized in that: The pump body (1) is provided with a pressure switch (14) connected to the oil outlet (61), and a connection socket (15) for electrical connection with external information equipment is provided on one side of the pressure switch (14).

9. A VDC hydraulic pump according to claim 6, characterized in that: The oil delivery mechanism (8) includes a refueling pipe (81) and a plug (82). The refueling pipe (81) is mounted on the support base (11) and connected to the oil delivery pipe (12). The plug (82) is fitted onto the end of the refueling pipe (81) away from the oil delivery pipe (12) and blocks the oil delivery pipe (12). A high-level valve body (111) is mounted on the support base (11) and located at the refueling pipe (81). The high-level valve body (111) has a vertical upper edge. A force-bearing rod (112) is installed for directional sliding. When the lifting plate (13) slides to the top of the inner side of the pump body (1), one end of the force-bearing rod (112) abuts against one side of the lifting plate (13). A force-bearing spring (113) is sleeved on the force-bearing rod (112). The force-bearing spring (113) is connected to the high liquid level valve body (111). An indicator rod (114) is provided on the top of the force-bearing rod (112) and outside the high liquid level valve body (111).

10. A VDC hydraulic pump according to claim 6, characterized in that: The sensing module includes an ultrasonic sensor (7) disposed on the top of the pump body (1). One end of the probe of the ultrasonic sensor (7) is located inside the pump body (1) and is vertically downward. The ultrasonic sensor (7) is used to collect the high and low liquid level signals of the lifting plate (13).

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