Loading hydraulic test system for closed pump motor

Abstract

The invention provides a closed pump motor loading hydraulic test system which comprises an oil supply way, a motor module, a first connecting oil way, a second connecting oil way, an adjusting module, a cartridge valve group and an oil return way, the oil supply way is connected with one end of the cartridge valve group, and the other end of the cartridge valve group is connected with the first connecting oil way and the second connecting oil way. The third end of the cartridge valve set is connected with an oil return oil way, the oil return oil way is connected with the oil supply oil way through a first reversing valve, the first connecting oil way is connected with the adjusting module through a second reversing valve to form a first adjusting oil way, and the second connecting oil way is connected with the adjusting module through a second reversing valve to form a second adjusting oil way. The motor module is connected with a connector PA1 in the first connecting oil way and a connector PB1 in the second connecting oil way. Through mutual cooperation of the overflow valves in the different branch oil paths, multiple different hydraulic oil pressures required by the loading motor during testing can be accurately adjusted, so that the accuracy of the testing result of the loading motor is ensured.

Description

Technical Field

[0001] This invention relates to the field of motor hydraulic testing technology, and specifically to a closed-loop pump motor loading hydraulic testing system. Background Technology

[0002] Hydraulic technology applies a small force through a small-area piston, which allows the liquid pressure to be uniformly transmitted to a large-area piston to generate a multiplier effect, thus achieving a power amplification effect. This characteristic makes it a key technology for connecting mechanical energy and hydraulic pressure, and it can be applied to scenarios requiring high thrust or high-precision control or to the testing of hydraulic valves.

[0003] For example, Chinese patent document No. 202210857640.9, published on September 27, 2022, discloses a hydraulic pump loading test system, including a fixed displacement pump and a hydraulic motor; the inlet end of the hydraulic motor is connected to the outlet end of the fixed displacement pump; an overflow valve, the inlet end of which is connected to the outlet end of the fixed displacement pump; a drive unit, the power output end of which is connected to the overflow pressure regulating end of the overflow valve; a load, the power input end of which is connected to the power output end of the hydraulic motor; and a control device, the signal output end of which is electrically connected to the signal input end of the load and the signal input end of the drive unit, respectively.

[0004] The aforementioned literature describes a control device that controls the drive components based on the torque of the hydraulic motor to increase the overflow pressure of the relief valve, thereby increasing the fluid flow between the fixed displacement pump and the hydraulic motor. This maintains the rated speed of the hydraulic motor, ensuring the accuracy of the load test results while simultaneously performing a load test on the fixed displacement pump. However, this process only uses a single relief valve to control the flow of hydraulic oil entering the directional valve. Consequently, when performing multiple tests on the load motor with different hydraulic oil pressure values, the pressure value of the entire relief valve needs to be readjusted, which can easily lead to inaccurate test results for the load motor. Summary of the Invention

[0005] The purpose of this invention is to provide a closed-loop pump motor loading hydraulic testing system. By cooperating with the overflow valves in different oil circuits, it is possible to accurately adjust the hydraulic oil pressure required for multiple tests of the loading motor, thereby ensuring the accuracy of the loading motor test results.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a closed-loop pump motor loading hydraulic testing system, comprising an oil supply circuit, a motor module, a first connecting oil circuit, a second connecting oil circuit, an adjustment module, a cartridge valve assembly, and a return oil circuit. The oil supply circuit is connected to one end of the cartridge valve assembly. The oil supply circuit includes a first relief valve, one end of which is connected to one end of the second relief valve assembly. The other end of the second relief valve is connected to an oil tank. The other end of the cartridge valve assembly is connected to both the first connecting oil circuit and the second connecting oil circuit. The third end of the valve assembly is connected to the return oil circuit, and the return oil circuit is connected to the supply oil circuit through the first reversing valve. The first connecting oil circuit is connected to the regulating module through the second reversing valve to form the regulating oil circuit one. The second connecting oil circuit is connected to the regulating module through the second reversing valve to form the regulating oil circuit two. The regulating module includes the second overflow valve. One end of the second overflow valve is connected to the oil tank, and the other end of the second overflow valve is connected to the second reversing valve. The motor module is connected to interface PA1 in the first connecting oil circuit and interface PB1 in the second connecting oil circuit.

[0007] The above settings, when conducting multiple tests on the loading motor with different hydraulic oil pressure values, can first partially depressurize the hydraulic oil entering the cartridge valve assembly through the relief valve pair in the oil supply circuit. This ensures that the hydraulic oil pressure entering the cartridge valve assembly meets the requirements of the loading motor test, and also protects the cartridge valve assembly from damage caused by excessive hydraulic oil pressure. The hydraulic oil then enters the loading motor through interface PA1 in connecting oil circuit one, flows back to the cartridge valve assembly through interface PB1 in connecting oil circuit two, and finally flows back to the oil tank through the return oil circuit. When it is necessary to change the hydraulic oil pressure value entering the loading motor, the pressure value of relief valve two in the regulating module can be changed, allowing pressurized hydraulic oil to enter interface PA1 or interface PB1 through the connecting oil circuit. This directly avoids pressurized hydraulic oil entering the cartridge valve assembly, protecting the cartridge valve assembly while meeting the requirements of multiple tests on the loading motor with different hydraulic oil pressure values, thus making the loading motor test results more accurate.

[0008] Furthermore, the oil supply circuit includes a ball valve, a flexible joint, a hydraulic pump, and a check valve. The hydraulic pump is connected to a drive device. One end of the ball valve is connected to the oil tank, and the other end of the ball valve is connected to one end of the flexible joint. The other end of the flexible joint is connected to one end of the hydraulic pump, and the other end of the hydraulic pump is connected to one end of the check valve. The other end of the check valve is connected to a relief valve, a directional valve, and a cartridge valve assembly.

[0009] The above settings allow hydraulic oil to flow through check valve 1 to relief valve 1, directional valve 1, and cartridge valve assembly via hydraulic pump 1. Check valve 1 prevents hydraulic oil backflow and adjusts the pressure of hydraulic oil entering directional valve 1 and cartridge valve assembly by regulating the pressure value of relief valve 1, thereby protecting cartridge valve assembly and meeting the requirements of loading motor test.

[0010] Furthermore, the motor module includes a test motor and a loading motor, which are connected by a torque tachometer. The test motor has interfaces a1 and a2 at both ends, and the loading motor has interfaces b1 and b2 at both ends.

[0011] The above setup allows interface PA1 in oil circuit one and interface PB1 in oil circuit two to be connected to the loading motor via interfaces b1 and b2, respectively. Interfaces a1 and a2 of the test motor form a circuit by connecting to the oil tank. This enables the loading motor to be driven, which in turn drives the test motor to rotate, allowing for multiple tests of different hydraulic oil pressure values.

[0012] Furthermore, the connecting oil circuit one includes a flow meter one, a ball valve two, an interface T1 and an interface PA1. The interface PA1 is connected to one end of the ball valve two and the cartridge valve assembly, respectively. The other end of the ball valve two is connected to one end of the flow meter one, and the other end of the flow meter one is connected to the interface T1. The second connecting oil circuit includes a flow meter, a ball valve, an interface T2, and an interface PB1. The interface PB1 is connected to one end of the ball valve and the cartridge valve assembly, respectively. The other end of the ball valve is connected to one end of the flow meter, and the other end of the flow meter is connected to the interface T2.

[0013] The above settings allow for the following: when hydraulic oil enters the loading motor from interface PA1 for testing and the hydraulic oil pressure needs to be changed, additional hydraulic oil can enter the loading motor from interface PA1 through connection oil circuit one to test different hydraulic oil pressure values. After the hydraulic oil is reversed, when hydraulic oil enters the loading motor from interface PB1 for testing and the hydraulic oil pressure needs to be changed, additional hydraulic oil can enter the loading motor from interface PB1 through connection oil circuit two to test different hydraulic oil pressure values, thus satisfying tests for different directions and different hydraulic oil pressure values.

[0014] Furthermore, the cartridge valve assembly includes cartridge valve one, cartridge valve two, cartridge valve three, and cartridge valve four. Interface PA1 is connected to interface z1 of cartridge valve one, interface z9 of cartridge valve three, and interface z10 of cartridge valve three, respectively. Interface z3 of cartridge valve one is connected to interface z2 of cartridge valve one, interface z5 of cartridge valve two, interface z6 of cartridge valve two, and the return oil circuit, respectively. Interface z4 of cartridge valve two is connected to interface PB1, interface z61 of cartridge valve four, and interface z7 of cartridge valve four, respectively. Interface z11 of cartridge valve three and interface z8 of cartridge valve four are both connected to the other end of check valve one.

[0015] The above settings allow regulating oil circuit one and regulating oil circuit two to act on different cartridge valves in the cartridge valve assembly for adjustment. This allows hydraulic oil to flow from the supply line through the cartridge valve assembly, then through interface PA1 into the loading motor for testing. After flowing through the loading motor, it flows back to the cartridge valve assembly through interface PB1 and then back to the oil tank through the return oil circuit. Alternatively, by reversing the hydraulic oil flow, the hydraulic oil can flow from the supply line through the cartridge valve assembly, then through interface PB1 into the loading motor for testing. After flowing through the loading motor, it flows back to the cartridge valve assembly through interface PA1 and then back to the oil tank through the return oil circuit.

[0016] Furthermore, the adjustment module includes a second directional control valve, a second hydraulic pump, a second check valve, and a fourth ball valve. Interface T1 is connected to interface T3 of the second directional control valve, interface T2 is connected to interface T4 of the second directional control valve, interface T5 of the second directional control valve is connected to one end of the second relief valve and the second check valve, respectively, interface T6 of the second directional control valve and the other end of the second relief valve are both connected to the oil tank, the other end of the second check valve is connected to one end of the second hydraulic pump, the other end of the second hydraulic pump is connected to one end of the fourth ball valve, and the other end of the fourth ball valve is connected to the oil tank.

[0017] The above settings allow the hydraulic pump two to direct the hydraulic oil to the directional valve two, adjusting the pressure of the relief valve two according to the actual hydraulic oil pressure required by the loading motor. This ensures that the pressure of the hydraulic oil flowing through the directional valve two to either the connecting oil circuit one or the connecting oil circuit two matches the pressure of the hydraulic oil required by the loading motor.

[0018] Furthermore, the return oil circuit includes a return oil overflow valve, a reversing valve, and a return oil filter. One end of the return oil overflow valve is connected to the cartridge valve assembly, and the other end of the return oil overflow valve is connected to the interface T7 of the reversing valve. The interface T9 of the reversing valve is connected to the return oil filter, and the return oil filter is connected to the oil tank.

[0019] The above settings facilitate the provision of back pressure to the returning hydraulic oil through the return oil relief valve, thus preventing the loading motor from rotating too fast during testing. Before the hydraulic oil enters the loading motor, the first directional valve acts on the cartridge valves of the cartridge valve assembly through a portion of the hydraulic oil, keeping the cartridge valves closed. This allows the hydraulic oil entering the cartridge valve assembly to directly enter the loading motor through interface PA1. Then, the first directional valve reverses the flow, allowing the hydraulic oil flowing back from interface PB1 to the cartridge valve assembly to return to the return oil circuit through the cartridge valves and then back to the oil tank. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the hydraulic connection of the oil supply circuit, connecting oil circuit one, connecting oil circuit two, cartridge valve assembly and return oil circuit of the present invention.

[0021] Figure 2 This is a hydraulic diagram of the adjustment module of the present invention.

[0022] Figure 3 This is a hydraulic diagram of the motor module of the present invention.

[0023] Figure 4 This is a schematic diagram of the connection of the cartridge valve assembly of the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 1-4 As shown, a closed-loop pump motor loading hydraulic testing system includes an oil supply circuit, a motor module, a first connecting oil circuit, a second connecting oil circuit, an adjustment module, a cartridge valve assembly w0, and a return oil circuit. The oil supply circuit is connected to one end of the cartridge valve assembly, the other end of the cartridge valve assembly is connected to both the first and second connecting oil circuits, and the third end of the cartridge valve assembly is connected to the return oil circuit. The return oil circuit is connected to the oil supply circuit via a directional valve w11. Figure 4As shown, the cartridge valve assembly includes cartridge valve one (w1), cartridge valve two (w2), cartridge valve three (w3), and cartridge valve four (w4). Interface PA1 is connected to interface z1 of cartridge valve one (w1), interface z9 of cartridge valve three (w3), and interface z10 of cartridge valve three (w3). Interface z3 of cartridge valve one (w1) is connected to interface z2 of cartridge valve one (w1), interface z5 of cartridge valve two (w2), interface z6 of cartridge valve two (w2), and the return oil circuit. Interface z4 of cartridge valve two (w2) is connected to interface PB1, interface z61 of cartridge valve four (w4), and interface z7 of cartridge valve four (w4). Interface z11 of cartridge valve three (w3) and interface z4 of cartridge valve four (w4) are connected to... Both ports z8 and w16 are connected to the other end of the one-way valve. This allows regulating oil circuit one and regulating oil circuit two to act on different cartridge valves in the cartridge valve assembly for regulation. This allows hydraulic oil to flow from the supply line through the cartridge valve assembly, then through port PA1 into the loading motor for testing. After flowing through the loading motor, it flows back to the cartridge valve assembly through port PB1 and then back to the oil tank through the return oil circuit. Alternatively, by reversing the hydraulic oil flow, the hydraulic oil can flow from the supply line through the cartridge valve assembly, then through port PB1 into the loading motor for testing. After flowing through the loading motor, it flows back to the cartridge valve assembly through port PA1 and then back to the oil tank through the return oil circuit.

[0026] like Figure 1 As shown, the oil supply circuit includes a ball valve W13, a flexible joint W14, a hydraulic pump W15, a check valve W16, and a relief valve W17. The hydraulic pump W15 is connected to a drive unit. One end of the ball valve W13 is connected to the oil tank, and the other end of the ball valve W13 is connected to one end of the flexible joint W14. The other end of the flexible joint W14 is connected to one end of the hydraulic pump W15, and the other end of the hydraulic pump W15 is connected to one end of the check valve W16. The other end of the check valve W16 is connected to the relief valve W17 and the directional valve W17, respectively. Interface T8 of component 1 is connected to interface Z11 of cartridge valve three (w3) and interface Z8 of cartridge valve four (w4) in the cartridge valve assembly. This allows hydraulic oil to flow through check valve one (w16) to relief valve one (w17), directional valve one (w11), and the cartridge valve assembly via hydraulic pump one (w15). Check valve one (w16) prevents backflow of hydraulic oil, and by adjusting the pressure value of relief valve one (w17), the hydraulic oil pressure entering directional valve one (w11) and the cartridge valve assembly can be adjusted, thus protecting the cartridge valve assembly and meeting the requirements of the loading motor test. A pressure sensor is connected to interface T8 of directional valve one (w11) to detect the hydraulic oil pressure entering the cartridge valve assembly. In this embodiment, drive device one is a drive motor.

[0027] like Figure 1 , Figure 2 and 3As shown, connecting oil circuit one is connected to the regulating module via reversing valve two W5 to form regulating oil circuit one, and connecting oil circuit two is connected to the regulating module via reversing valve two W5 to form regulating oil circuit two. The motor module is connected to interface PA1 in connecting oil circuit one and interface PB1 in connecting oil circuit two. The motor module includes a test motor and a loading motor. The test motor and the loading motor are connected via a torque tachometer. The two ends of the test motor are respectively provided with interface a1 and interface a2, and the two ends of the loading motor are respectively provided with interface b1 and interface b2. This facilitates the connection of interface PA1 in connecting oil circuit one and interface PB1 in connecting oil circuit two to the loading motor via interface b1 and interface b2, respectively. The interfaces a1 and a2 of the test motor form a circuit by connecting to the oil tank. In this way, by driving the loading motor, the test motor can be driven to rotate, realizing multiple tests of different hydraulic oil pressure values.

[0028] like Figure 1 As shown, the first connecting oil circuit includes a flow meter W18, a ball valve W19, an interface T1, and an interface PA1. Interface PA1 is connected to one end of the ball valve W19 and a cartridge valve assembly, respectively. The other end of the ball valve W19 is connected to one end of the flow meter W18, and the other end of the flow meter W18 is connected to interface T1. The second connecting oil circuit includes a flow meter W20, a ball valve W21, an interface T2, and an interface PB1. Interface PB1 is connected to one end of the ball valve W21 and a cartridge valve assembly, respectively. The other end of the ball valve W21 is connected to one end of the flow meter W20, and the other end of the flow meter W20 is connected to... Connected to interface T2, when hydraulic oil enters the loading motor from interface PA1 for testing and the hydraulic oil pressure needs to be changed, additional hydraulic oil can enter the loading motor from interface PA1 through connection oil circuit one to test different hydraulic oil pressure values; and after the hydraulic oil is reversed, when hydraulic oil enters the loading motor from interface PB1 for testing and the hydraulic oil pressure needs to be changed, additional hydraulic oil can enter the loading motor from interface PB1 through connection oil circuit two to test different hydraulic oil pressure values, thus satisfying tests for different directions and different hydraulic oil pressure values.

[0029] like Figure 2As shown, the adjustment module includes a directional valve 2w5, a relief valve 2w6, a hydraulic pump 2w7, a check valve 2w8, and a ball valve 4w9. Interface T1 is connected to interface T3 of directional valve 2w5, interface T2 is connected to interface T4 of directional valve 2w5, interface T5 of directional valve 2w5 is connected to one end of both relief valve 2w6 and check valve 2w8, interface T6 of directional valve 2w5 and the other end of relief valve 2w6 are both connected to the oil tank, the other end of check valve 2w8 is connected to one end of hydraulic pump 2w7, the other end of hydraulic pump 2w7 is connected to one end of ball valve 4w9, and the other end of ball valve 4w9 is connected to the oil tank. Thus, when hydraulic oil flows from hydraulic pump 2w7 to directional valve 2w5, the pressure value of relief valve 2w6 can be adjusted according to the actual hydraulic oil pressure value required by the loading motor, thereby ensuring that the pressure value of the hydraulic oil flowing through directional valve 2w5 to the oil circuit 1 or the oil circuit 2 matches the hydraulic oil pressure value required by the loading motor. In this embodiment, hydraulic pump 2w7 is connected to drive device 2, which is a drive motor.

[0030] like Figure 1 As shown, the return oil circuit includes a return oil relief valve W10, a directional valve W11, and a return oil filter W12. One end of the return oil relief valve W10 is connected to the cartridge valve assembly, and the other end is connected to port T7 of the directional valve W11. Port T9 of the directional valve W11 is connected to one end of the return oil filter W12, while the other end of the return oil filter W12 is connected to the oil tank. This facilitates the provision of back pressure to the returning hydraulic oil through the return oil relief valve W10, thus preventing the loading motor from rotating too fast during testing. The directional valve W11... Before the hydraulic oil enters the loading motor, a portion of the hydraulic oil acts on cartridge valves W1 and W2 of the cartridge valve assembly, causing them to be closed while cartridge valves W3 and W4 are opened. This allows the hydraulic oil entering the cartridge valve assembly to directly enter the loading motor through interface PA1. Then, the directional valve W11 is reversed, causing the hydraulic oil flowing back from interface PB1 to the cartridge valve assembly to flow back through cartridge valves W1 and W2 to the return oil circuit, and finally back to the oil tank.

[0031] In this embodiment, the test of different hydraulic oil pressure values ​​for forward steering of the loading motor r5 is used as an example. First, the pressure value of the relief valve W17 is adjusted, and the directional valve W11 is switched, so that the interface T7 of the directional valve W11 is connected to the interface T8 of the directional valve W11. Then, the relief valve II in the adjustment module is adjusted, so that the hydraulic oil in the adjustment oil circuit II acts on the interface Z61 of the cartridge valve W4, and the cartridge valve W4 is in the closed state. At the same time, it acts on the interface Z4 of the cartridge valve W2, so that the cartridge valve W2 is in the open state, pushing the cartridge valve W2. The valve core moves downward, causing the hydraulic oil to connect to the port z2 of cartridge valve 1 W1 through the return oil circuit. This causes the valve core of cartridge valve 1 W1 to move upward and be in the closed state. At this time, the hydraulic oil in the supply oil circuit acts on the port z11 of cartridge valve 3 W3 after passing through the check valve 1 W16, pushing the valve core of cartridge valve 3 W3 to move upward, causing cartridge valve 3 W3 to be in the open state. In this way, the hydraulic oil can enter the loading motor through the port PA1, and after passing through the loading motor, it flows back to the port z4 of cartridge valve 2 W2 through the port PB1, and then flows back to the oil tank through the return oil circuit to form a complete circuit.

[0032] When the load motor r5 is in negative direction, oil enters through cartridge valve four w4, which then causes cartridge valve one and cartridge valve four to open and form a circuit.

[0033] During the oil return process, before the hydraulic oil enters the loading motor, the directional valve 1 W11 reverses, connecting port T7 of directional valve 1 W11 with port T9 of directional valve 1 W11. This allows the hydraulic oil to flow back to the oil tank. At the same time, ball valve 2 W19 in the oil circuit 1 is closed. Meanwhile, the hydraulic oil flowing back from port PB1 to port Z4 of cartridge valve 2 W2 flows to port Z2 of cartridge valve 1 W1, causing the valve core of cartridge valve 1 W1 to move upward and close.

[0034] After completing the above process, when it is necessary to test the loading motor with different hydraulic oil pressure values, close the ball valve 3 W21 in the second connecting oil circuit. By adjusting the overflow valve 2 W6 in the regulating module, the hydraulic oil in the regulating oil circuit 1 is adjusted to reach the hydraulic oil pressure value required for the loading motor to perform different hydraulic oil pressure values. Then, the reversing valve 2 W5 is reversed, so that the interface T5 of the reversing valve 2 W5 is connected to the interface T3 of the reversing valve 2 W5. This allows the hydraulic oil used to test the loading motor with different hydraulic oil pressure values ​​to flow to the interface PA1 through the first connecting oil circuit. In this embodiment, since the loading motor is rotating, it draws in most of the hydraulic oil from the first regulating oil circuit to flow to the interface PA1, such as 90% of the total hydraulic oil in the first regulating oil circuit. A small portion of the hydraulic oil in the first regulating oil circuit (such as 10% of the total hydraulic oil in the first regulating oil circuit) flows to the interface Z1 of the cartridge valve 1 W1, but it is still less than the amount required to push the valve core of the cartridge valve 1 W1 downward. The pressure (most of the oil pressure in the regulating oil circuit can be adjusted to the PA1 port by selecting the cartridge valve with a larger oil pressure start-up pressure) means that the cartridge valve is still closed at this time. When the hydraulic oil enters the loading motor through the PA1 port and flows back to the cartridge valve assembly from the PB1 port, it will again pass through the Z4 port of the cartridge valve, keeping the cartridge valve open. The oil pressure at the Z6 port of the cartridge valve is the same as the Z4 port, so it will not be closed. Then, the hydraulic oil flows from the Z5 port of the cartridge valve to the Z2 port of the cartridge valve, keeping the cartridge valve closed. This directly avoids pressurized hydraulic oil entering the cartridge valve assembly from the oil supply circuit and changing the original oil pressure in the oil supply circuit. This protects the cartridge valve assembly while meeting the requirements for multiple tests of different hydraulic oil pressure values ​​for the loading motor, thus making the loading motor test results more accurate.

Claims

1. A closed-loop pump motor loading hydraulic testing system, characterized in that: The system includes an oil supply circuit, a motor module, a first connecting oil circuit, a second connecting oil circuit, a regulating module, a cartridge valve assembly, and a return oil circuit. The oil supply circuit is connected to one end of the cartridge valve assembly. The oil supply circuit includes a first overflow valve, one end of which is connected to one end of the second overflow valve assembly. The other end of the second overflow valve is connected to the oil tank. The other end of the cartridge valve assembly is connected to both the first and second connecting oil circuits. The third end of the cartridge valve assembly is connected to the return oil circuit. The return oil circuit is connected to the oil supply circuit via a first reversing valve. The first connecting oil circuit is connected to the regulating module via a second reversing valve to form the first regulating oil circuit. The second connecting oil circuit is connected to the regulating module via a second reversing valve to form the second regulating oil circuit. The regulating module includes a second overflow valve, one end of which is connected to the oil tank. The other end of the second overflow valve is connected to a second reversing valve. The motor module is connected to interface PA1 in the first connecting oil circuit and interface PB1 in the second connecting oil circuit.

2. The closed-loop pump motor loading hydraulic testing system according to claim 1, characterized in that: The oil supply circuit includes a ball valve, a flexible joint, a hydraulic pump, and a check valve. The hydraulic pump is connected to a drive device. One end of the ball valve is connected to the oil tank, and the other end of the ball valve is connected to one end of the flexible joint. The other end of the flexible joint is connected to one end of the hydraulic pump, and the other end of the hydraulic pump is connected to one end of the check valve. The other end of the check valve is connected to a relief valve, a directional valve, and a cartridge valve assembly.

3. The closed-loop pump motor loading hydraulic testing system according to claim 1, characterized in that: The motor module includes a test motor and a loading motor. The test motor and the loading motor are connected by a torque tachometer. The two ends of the test motor are respectively provided with interface a1 and interface a2, and the two ends of the loading motor are respectively provided with interface b1 and interface b2.

4. The closed-loop pump motor loading hydraulic testing system according to claim 1, characterized in that: The connecting oil circuit includes a flow meter, a ball valve, an interface T1, and an interface PA1. Interface PA1 is connected to one end of the ball valve and the cartridge valve assembly, respectively. The other end of the ball valve is connected to one end of the flow meter, and the other end of the flow meter is connected to the interface T1. The second connecting oil circuit includes a flow meter, a ball valve, an interface T2, and an interface PB1. The interface PB1 is connected to one end of the ball valve and the cartridge valve assembly, respectively. The other end of the ball valve is connected to one end of the flow meter, and the other end of the flow meter is connected to the interface T2.

5. The closed-loop pump motor loading hydraulic testing system according to claim 1, characterized in that: The cartridge valve assembly includes cartridge valve one, cartridge valve two, cartridge valve three, and cartridge valve four. Interface PA1 is connected to interface z1 of cartridge valve one, interface z9 of cartridge valve three, and interface z10 of cartridge valve three, respectively. Interface z3 of cartridge valve one is connected to interface z2 of cartridge valve one, interface z5 of cartridge valve two, interface z6 of cartridge valve two, and the return oil circuit, respectively. Interface z4 of cartridge valve two is connected to interface PB1, interface z61 of cartridge valve four, and interface z7 of cartridge valve four, respectively. Interface z11 of cartridge valve three and interface z8 of cartridge valve four are both connected to the other end of check valve one.

6. The closed-loop pump motor loading hydraulic testing system according to claim 1, characterized in that: The regulating module includes a second directional control valve, a second hydraulic pump, a second check valve, and a fourth ball valve. Interface T1 is connected to interface T3 of the second directional control valve, interface T2 is connected to interface T4 of the second directional control valve, interface T5 of the second directional control valve is connected to one end of the second relief valve and one end of the second check valve, interface T6 of the second directional control valve and the other end of the second relief valve are both connected to the oil tank, the other end of the second check valve is connected to one end of the second hydraulic pump, the other end of the second hydraulic pump is connected to one end of the fourth ball valve, and the other end of the fourth ball valve is connected to the oil tank.

7. The closed-loop pump motor loading hydraulic testing system according to claim 1, characterized in that: The return oil circuit includes a return oil overflow valve, a reversing valve, and a return oil filter. One end of the return oil overflow valve is connected to the cartridge valve assembly, and the other end of the return oil overflow valve is connected to the interface T7 of the reversing valve. The interface T9 of the reversing valve is connected to the return oil filter, and the return oil filter is connected to the oil tank.

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