A dual variable hydraulic pump power recovery test system

Abstract

A kind of dual variable hydraulic pump power recovery test system, including oil supplement pump group, variable frequency motor, test pump group, power recovery motor, controller, flow regulating valve group, oil tank, test pump group oil outlet and test pump flow sensor group oil inlet in flow regulating valve group are communicated, test pump flow sensor group oil outlet and power recovery motor flow sensor oil inlet, oil return flow sensor oil inlet are communicated, oil return flow sensor oil outlet and oil tank are communicated, power recovery motor A mouth, B mouth are communicated with power recovery motor flow sensor oil outlet, oil tank, oil supplement pump group oil outlet is communicated with power recovery motor flow sensor oil inlet by oil supplement pump flow sensor.This design is when test pump test different speed conditions, according to each flow sensor signal closed loop self-adapting regulation oil supplement pump group displacement, so that oil supplement pump group only output test pump group and power recovery motor difference flow, realize full-flow power recovery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hydraulic system test, and particularly relates to a double-variable hydraulic pump power recovery test system, which is suitable for closed-loop self-adaptive regulation to realize full-flow power recovery. BACKGROUND

[0002] Efficiency test is an important part of hydraulic pump type test. The test requires measuring the volumetric efficiency of the test pump at least at six equally divided points in the range from no-load pressure to rated pressure, and at least at eight equally divided points in the range from 10% to 100% of rated speed, so as to obtain the curves of efficiency, flow and power varying with pressure and speed. If the test pump is a variable pump, the flow-pressure characteristic at different pressures also needs to be tested. When the pressure rating of the test pump is high and the rated speed is high, the test conditions need to be adjusted for many times during the test.

[0003] Generally, when adjusting the test conditions, the test system usually adjusts the pressure of the overflow valve by observing the instruments, which belongs to open-loop regulation, and the process is tedious and the degree of automation is low. Moreover, full-flow power recovery cannot be realized, and the energy consumption is high. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned problems existing in the prior art, and to provide a double-variable hydraulic pump power recovery test system capable of realizing closed-loop self-adaptive regulation and full-flow power recovery.

[0005] To achieve the above purpose, the present application provides the following technical solutions:

[0006] A double-variable hydraulic pump power recovery test system, which comprises an oil supplementing pump group, a variable frequency motor, a test pump group, a power recovery motor, a controller, a flow regulating valve group, and an oil tank. The flow regulating valve group comprises an oil supplementing pump flow sensor, a power recovery motor flow sensor, a test pump flow sensor group, and an oil return flow sensor. The variable frequency motor is in driving cooperation with the test pump group and the power recovery motor. The oil outlet of the test pump group is in communication with the oil inlet of the test pump flow sensor group. The oil outlet of the test pump flow sensor group is in communication with the oil inlet of the power recovery motor flow sensor and the oil inlet of the oil return flow sensor. The oil outlet of the oil return flow sensor is in communication with the oil tank. The oil outlet of the power recovery motor flow sensor is in communication with the A port of the power recovery motor. The B port of the power recovery motor is in communication with the oil tank. The oil outlet of the oil supplementing pump group is in communication with the oil inlet of the power recovery motor flow sensor through the oil supplementing pump flow sensor.

[0007] The signal input end of the controller is connected with the signal output ends of the power recovery motor flow sensor, the test pump flow sensor group, the oil return flow sensor, and the oil supplementing pump flow sensor. The signal output end of the controller is connected with the signal output end of the oil supplementing pump group.

[0008] The test pump group includes a test pump, a first one-way valve, and a test pump pressure regulating valve installed on the test pump, the test system further includes a pressure regulating valve group and a control valve group, the pressure regulating valve group includes a test pump outlet pressure sensor, a loading proportional relief valve inlet pressure sensor, an oil supplement pump outlet pressure sensor, and a power recovery motor inlet pressure sensor, and the control valve group includes the loading proportional relief valve.

[0009] The oil inlet of the test pump is communicated with an oil tank, the oil outlet of the test pump is communicated with the oil inlet of a test pump flow sensor group through a first one-way valve, the test pump outlet pressure sensor is arranged close to the oil outlet of the first one-way valve, the loading proportional relief valve inlet pressure sensor is arranged close to the oil outlet of the test pump flow sensor group, the oil supplement pump outlet pressure sensor is arranged between the oil outlet of the oil supplement pump group and the oil inlet of an oil supplement pump flow sensor, the power recovery motor inlet pressure sensor is arranged between the oil outlet of a power recovery motor flow sensor and the A port of the power recovery motor, and the oil inlets and outlets of the loading proportional relief valve are respectively communicated with the oil outlet of the test pump flow sensor group and the oil inlet of an oil return flow sensor.

[0010] The signal output ends of the test pump outlet pressure sensor, the loading proportional relief valve inlet pressure sensor, the oil supplement pump outlet pressure sensor, and the power recovery motor inlet pressure sensor are connected with the signal input end of the controller, and the signal output end of the controller is connected with the signal input ends of the test pump pressure regulating valve, the oil supplement pump group, and the loading proportional relief valve.

[0011] The oil supplement pump group includes a main motor, an oil supplement pump, a control pump, a variable cylinder, a displacement control valve, a pressure control valve, a shuttle valve, a proportional pressure reducing valve, a first electromagnetic reversing valve, a pressure reducing valve, a first relief valve, and a second one-way valve, the main motor is in driving cooperation with the oil supplement pump and the control pump, the oil inlets of the oil supplement pump and the control pump are communicated with an oil tank, the oil outlet of the oil supplement pump is communicated with the oil inlet of the second one-way valve and the B port of the shuttle valve, the oil outlet of the second one-way valve is communicated with the oil inlet of an oil supplement pump flow sensor, the oil outlet of the control pump is communicated with the oil inlets of the pressure reducing valve, the proportional pressure reducing valve, and the first relief valve, the oil outlet of the pressure reducing valve is communicated with the A port of the shuttle valve, the C port of the shuttle valve is communicated with the rod cavity of the variable cylinder, the P port of the pressure control valve, and the X port of the pressure control valve, the rodless cavity of the variable cylinder is communicated with the A port of the displacement control valve, the T port and the P port of the displacement control valve are respectively communicated with the oil tank and the A port of the pressure control valve, the T port and the X port of the pressure control valve are respectively communicated with the oil tank and the A port of the first electromagnetic reversing valve, the P port of the first electromagnetic reversing valve is communicated with the oil outlet of the proportional pressure reducing valve, and the L port of the first electromagnetic reversing valve and the oil outlet of the first relief valve are both communicated with the oil tank.

[0012] The signal output end of the controller is connected to the signal input ends of the proportional pressure reducing valve and the displacement control valve.

[0013] The test pump flow sensor group includes two test pump flow sensors connected in parallel, a first ball valve is connected in series at the oil inlet of the test pump flow sensor, the oil outlets of the two test pump flow sensors together constitute the oil outlet of the test pump flow sensor group, and the oil inlets of the two first ball valves together constitute the oil inlet of the test pump flow sensor group.

[0014] The loading proportional relief valve includes a first two-way plug valve and a first pilot proportional relief valve. The A port of the first two-way plug valve is connected to the oil outlet of the test pump flow sensor group, the B port of the first two-way plug valve is connected to the oil inlet of the return oil flow sensor, the spring chamber of the first two-way plug valve is connected to the P port of the first pilot proportional relief valve, the T port of the first pilot proportional relief valve is connected to the oil inlet of the return oil flow sensor, and the signal input end of the first pilot proportional relief valve is connected to the signal output end of the controller.

[0015] The control valve group also includes a back-pressure proportional relief valve, which includes a second two-way plug valve and a second pilot proportional relief valve. The A port and B port of the second two-way plug valve are respectively connected to the B port of the power recovery motor and the oil tank. The spring chamber of the second two-way plug valve is connected to the P port of the second pilot proportional relief valve. The T port of the second pilot proportional relief valve is connected to the oil tank.

[0016] The control valve group also includes a first safety valve, which includes a third two-way plug valve and a third pilot proportional relief valve. The A port and B port of the third two-way plug valve are respectively connected to the oil outlet of the oil charge pump flow sensor and the oil tank. The spring chamber of the third two-way plug valve is connected to the P port of the third pilot proportional relief valve. The T port of the third pilot proportional relief valve is connected to the oil tank. The signal input end of the third pilot proportional relief valve is connected to the signal output end of the controller.

[0017] The control valve group also includes a second safety valve, which includes a fourth two-way plug valve and a second overflow valve. Port A and port B of the fourth two-way plug valve are respectively connected to the oil outlet of the first one-way valve and the oil inlet of the return oil flow sensor. The spring chamber of the fourth two-way plug valve is connected to the oil inlet of the second overflow valve, and the oil outlet of the second overflow valve is connected to the oil inlet of the return oil flow sensor.

[0018] The control valve group further comprises a two-way pressure reducing valve, the two-way pressure reducing valve comprises a fifth two-way plug valve, a second electromagnetic reversing valve, a pilot pressure reducing overflow valve, a fourth pilot proportional overflow valve and a third check valve, the A port of the fifth two-way plug valve is communicated with the oil outlet of the test pump flow sensor group, the B port of the fifth two-way plug valve is communicated with the A port of the pilot pressure reducing overflow valve and the oil inlet of the third check valve, the oil outlet of the third check valve is communicated with the oil inlet of the power recovery motor flow sensor, the spring cavity of the fifth two-way plug valve is communicated with the P port of the second electromagnetic reversing valve, the B port of the second electromagnetic reversing valve is communicated with the P port of the pilot pressure reducing overflow valve, the X port of the pilot pressure reducing overflow valve is communicated with the P port of the fourth pilot proportional overflow valve, and the T ports of the fourth pilot proportional overflow valve, the second electromagnetic reversing valve and the pilot pressure reducing overflow valve are all communicated with the oil tank.

[0019] The oil outlet of the test pump is communicated with the oil inlet of the power recovery motor flow sensor through the second ball valve.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] 1. The double-variable hydraulic pump power recovery test system comprises an oil supplement pump group, a variable frequency motor, a test pump group, a power recovery motor, a controller, a flow regulating valve group, an oil tank, the flow regulating valve group comprises an oil supplement pump flow sensor, a power recovery motor flow sensor, a test pump flow sensor group and an oil return flow sensor, the variable frequency motor is in transmission cooperation with the test pump group and the power recovery motor, the oil outlet of the test pump group is communicated with the oil inlet of the test pump flow sensor group, the oil outlets of the test pump flow sensor group are communicated with the oil inlet of the power recovery motor flow sensor and the oil inlet of the oil return flow sensor, the oil outlet of the oil return flow sensor is communicated with the oil tank, the oil outlet of the power recovery motor flow sensor is communicated with the A port of the power recovery motor, the B port of the power recovery motor is communicated with the oil tank, and the oil outlet of the oil supplement pump group is communicated with the oil inlet of the power recovery motor flow sensor through the oil supplement pump flow sensor; in the design, the oil supplement pump flow sensor, the power recovery motor flow sensor, the test pump flow sensor group and the oil return flow sensor are respectively used for detecting the flow at the oil outlet of the oil supplement pump group, the flow at the oil inlet of the power recovery motor, the flow at the oil outlet of the test pump group and the oil return flow, when the test pump is tested under different rotating speed conditions, the controller adjusts the displacement of the oil supplement pump group according to the flow signals in a closed loop, controls the oil supplement pump group to output only the difference flow between the test pump group and the power recovery motor, makes the flow at the oil inlet of the power recovery motor equal to the sum of the flow at the oil outlet of the oil supplement pump group and the flow at the oil outlet of the test pump group, and thus full-flow power recovery without overflow loss is realized. Therefore, the displacement of the oil supplement pump group can be adjusted according to the flow sensor signals in a closed loop when the test pump is tested under different rotating speed conditions, and full-flow power recovery is realized.

[0022] 2、The invention is a kind of dual variable hydraulic pump power recovery test system in, the pump group of test pump includes test pump, first check valve, install test pump on test pump pressure regulating valve, test system also includes pressure regulating valve group, control valve group, pressure regulating valve group includes test pump outlet pressure sensor, loading proportional relief valve inlet pressure sensor, oil supplement pump outlet pressure sensor, power recovery motor inlet pressure sensor, control valve group includes loading proportional relief valve, first safety valve, second safety valve, the oil inlet of loading proportional relief valve, oil outlet is communicated with the oil outlet of test pump flow sensor group, oil tank respectively, loading proportional relief valve includes the first two-way plug valve, first pilot proportional relief valve, oil supplement pump group includes main motor, oil supplement pump, control pump, variable cylinder, displacement control valve, pressure control valve, shuttle valve, proportional pressure reducing valve, first electromagnetic reversing valve, pressure reducing valve, first overflow valve, second check valve;In the design, test pump outlet pressure sensor, loading proportional relief valve inlet pressure sensor, oil supplement pump outlet pressure sensor, power recovery motor inlet pressure sensor are used for detecting the pressure at the oil outlet of test pump group, the pressure at the oil inlet of loading proportional relief valve, the pressure at the oil outlet of oil supplement pump group, the pressure at the oil inlet of power recovery motor, when test pump test different pressure conditions, the controller adjusts the set pressure of test pump pressure regulating valve, loading proportional relief valve, pressure control valve in oil supplement pump group, first safety valve, second safety valve according to the feedback of each pressure signal synchronous closed loop, so that the pressure at the oil outlet of oil supplement pump group is always equal to the set pressure of test pump pressure regulating valve, prevent some components from being unable to pressurize due to low pressure, at the same time, make the high pressure oil output by test pump group all enter power recovery motor, realize different pressure condition test. Therefore, the invention can adjust the pressure at the oil outlet of oil supplement pump group according to the feedback of each pressure signal synchronous closed loop when testing different pressure conditions, and realize full-flow power recovery.

[0023] 3、The invention is a kind of dual variable hydraulic pump power recovery test system, two-way pressure reducing valve includes the fifth two-way plug valve, second electromagnetic reversing valve, pilot pressure reducing relief valve, fourth pilot proportional relief valve, third check valve;Because the overload test pressure of test pump is greater than the rated pressure of power recovery motor, the high pressure oil output by test pump is reduced by two-way pressure reducing valve before entering power recovery motor, to prevent power recovery motor from being damaged due to overpressure, and the set pressure of two-way pressure reducing valve can be adjusted steplessly. Therefore, the invention can prevent power recovery motor from being damaged due to overpressure during overload test.

[0024] 4, In the double variable hydraulic pump power recovery test system, the back pressure proportional overflow valve comprises a second two-way plug valve and a second pilot proportional overflow valve; the design adjusts the output pressure of the power recovery motor through the back pressure proportional overflow, provides stable oil return back pressure for the power recovery motor, makes the power recovery motor rotate more smoothly, and meets the minimum working pressure requirement of the low pressure port of the power recovery motor. Therefore, the application provides stable oil return back pressure for the power recovery motor, so as to meet the minimum working pressure requirement of the low pressure port of the power recovery motor. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the application.

[0026] Figure 2 It is Figure 1 The structural schematic diagram of the two-way pressure reducing valve and the flow sensor group.

[0027] Figure 3 It is Figure 1 The structural schematic diagram of the first safety valve.

[0028] Figure 4 It is Figure 1 The structural schematic diagram of the test pump group.

[0029] Figure 5 It is Figure 1 The structural schematic diagram of the loading proportional overflow valve, the second safety valve and the back pressure proportional overflow valve.

[0030] Figure 6 It is Figure 1 The structural schematic diagram of the oil supplement pump group.

[0031] Figure 7 It is Figure 6 The structural schematic diagram of the displacement control valve and the pressure control valve.

[0032] In the figure, the oil supplement pump group 1, the main motor 11, the oil supplement pump 12, the pressure reducing valve 121, the first overflow valve 122, the second check valve 123, the control pump 13, the variable displacement cylinder 14, the displacement control valve 15, the pressure control valve 16, the shuttle valve 17, the proportional pressure reducing valve 18, the first electromagnetic reversing valve 19, the variable frequency motor 2, the test pump group 3, the test pump 31, the first check valve 32, the test pump pressure regulating valve 33, the second ball valve 34, the power recovery motor 4, the controller 5, the flow regulating valve group 6, the oil supplement pump flow sensor 61, the power recovery motor flow sensor 62, the test pump flow sensor group 63, the test pump flow sensor 631, the first ball valve 632, the oil return flow sensor 64, the oil tank 7, the pressure regulating valve group 8, the test pump outlet pressure sensor 81, the loading proportional overflow valve inlet pressure sensor 82, the oil supplement pump outlet pressure sensor 83, the power recovery motor inlet pressure sensor 84, the control valve group 9, the loading proportional overflow valve 91, the first two-way spool valve 911, the first pilot proportional overflow valve 912, the back pressure proportional overflow valve 92, the second two-way spool valve 921, the second pilot proportional overflow valve 922, the first safety valve 93, the third two-way spool valve 931, the third pilot proportional overflow valve 932, the second safety valve 94, the fourth two-way spool valve 941, the second overflow valve 942, the two-way pressure reducing valve 95, the fifth two-way spool valve 951, the second electromagnetic reversing valve 952, the pilot pressure reducing overflow valve 953, the fourth pilot proportional overflow valve 954, the third check valve 955. DETAILED DESCRIPTION

[0033] The application will be further described below in conjunction with the drawings and specific embodiments.

[0034] Reference Figures 1 to 7 A dual variable hydraulic pump power recovery test system, comprising an oil supplement pump group 1, a variable frequency motor 2, a test pump group 3, a power recovery motor 4, a controller 5, a flow regulating valve group 6, an oil tank 7, the flow regulating valve group 6 comprising an oil supplement pump flow sensor 61, a power recovery motor flow sensor 62, a test pump flow sensor group 63, an oil return flow sensor 64, the variable frequency motor 2 being in transmission cooperation with the test pump group 3 and the power recovery motor 4, an oil outlet of the test pump group 3 being in communication with an oil inlet of the test pump flow sensor group 63, an oil outlet of the test pump flow sensor group 63 being in communication with an oil inlet of the power recovery motor flow sensor 62 and an oil inlet of the oil return flow sensor 64, an oil outlet of the oil return flow sensor 64 being in communication with the oil tank 7, an oil outlet of the power recovery motor flow sensor 62 being in communication with an A port of the power recovery motor 4, a B port of the power recovery motor 4 being in communication with the oil tank 7, an oil outlet of the oil supplement pump group 1 being in communication with an oil inlet of the power recovery motor flow sensor 62 through the oil supplement pump flow sensor 61;

[0035] The signal input end of the controller 5 is connected to the signal output ends of the oil charge pump flow sensor 61, the power recovery motor flow sensor 62, the test pump flow sensor group 63, and the return oil flow sensor 64, and the signal output end of the controller 5 is connected to the signal output end of the oil charge pump group 1.

[0036] The test pump group 3 includes a test pump 31, a first one-way valve 32, and a test pump pressure regulating valve 33 installed on the test pump 31. The test system also includes a pressure regulating valve group 8 and a control valve group 9. The pressure regulating valve group 8 includes a test pump outlet pressure sensor 81, a loading proportional relief valve inlet pressure sensor 82, an oil charge pump outlet pressure sensor 83, and a power recovery motor inlet pressure sensor 84. The control valve group 9 includes a loading proportional relief valve 91.

[0037] The oil inlet of the test pump 31 is connected to the oil tank 7, and the oil outlet of the test pump 31 is connected to the oil inlet of the test pump flow sensor group 63 through the first one-way valve 32. The test pump outlet pressure sensor 81 is arranged near the oil outlet of the first one-way valve 32, and the loading proportional relief valve inlet pressure sensor 82 is arranged near the oil outlet of the test pump flow sensor group 63. The charge pump outlet pressure sensor 83 is arranged between the oil outlet of the charge pump group 1 and the oil inlet of the charge pump flow sensor 61. The power recovery motor inlet pressure sensor 84 is arranged between the oil outlet of the power recovery motor flow sensor 62 and the A port of the power recovery motor 4. The oil inlet and oil outlet of the loading proportional relief valve 91 are respectively connected to the oil outlet of the test pump flow sensor group 63 and the oil inlet of the return oil flow sensor 64;

[0038] The signal input end of the controller 5 is connected to the signal output ends of the test pump outlet pressure sensor 81, the loading proportional relief valve inlet pressure sensor 82, the oil replenishment pump outlet pressure sensor 83, and the power recovery motor inlet pressure sensor 84, and the signal output end of the controller 5 is connected to the signal input ends of the test pump pressure regulating valve 33, the oil replenishment pump group 1, and the loading proportional relief valve 91.

[0039] The oil replenishment pump group 1 includes a main motor 11, an oil replenishment pump 12, a control pump 13, a variable cylinder 14, a displacement control valve 15, a pressure control valve 16, a shuttle valve 17, a proportional pressure reducing valve 18, a first solenoid reversing valve 19, a pressure reducing valve 121, a first overflow valve 122, and a second one-way valve 123. The main motor 11 is in transmission cooperation with the oil replenishment pump 12 and the control pump 13. The oil inlets of the oil replenishment pump 12 and the control pump 13 are both connected to the oil tank 7. The oil outlet of the oil replenishment pump 12 is connected to the oil inlet of the second one-way valve 123 and the B port of the shuttle valve 17. The oil outlet of the second one-way valve 123 is connected to the oil inlet of the oil replenishment pump flow sensor 61. The oil outlet of the control pump 13 is connected to the oil inlet of the pressure reducing valve 121 and the oil inlet of the proportional pressure reducing valve 18. The oil inlet of the pressure reducing valve 122 is connected, the oil outlet of the pressure reducing valve 121 is connected with the A port of the shuttle valve 17, the C port of the shuttle valve 17 is connected with the rod chamber of the variable cylinder 14, the P port of the pressure control valve 16, and the X2 port of the pressure control valve 16, the rodless chamber of the variable cylinder 14 is connected with the A port of the displacement control valve 15, the T port and the P port of the displacement control valve 15 are connected with the oil tank 7 and the A port of the pressure control valve 16 respectively, the T port and the X1 port of the pressure control valve 16 are connected with the oil tank 7 and the A port of the first solenoid reversing valve 19 respectively, the P port of the first solenoid reversing valve 19 is connected with the oil outlet of the proportional pressure reducing valve 18, and the L port of the first solenoid reversing valve 19 and the oil outlet of the first relief valve 122 are both connected with the oil tank 7;

[0040] The signal output end of the controller 5 is connected to the signal input ends of the proportional pressure reducing valve 18 and the displacement control valve 15 .

[0041] The test pump flow sensor group 63 includes two parallel test pump flow sensors 631, and a first ball valve 632 is connected in series at the oil inlet of the test pump flow sensor 631. The oil outlets of the two test pump flow sensors 631 together constitute the oil outlet of the test pump flow sensor group 63, and the oil inlets of the two first ball valves 632 together constitute the oil inlet of the test pump flow sensor group 63.

[0042] The loading proportional relief valve 91 includes a first two-way plug valve 911 and a first pilot proportional relief valve 912. The A port of the first two-way plug valve 911 is connected to the oil outlet of the test pump flow sensor group 63, the B port of the first two-way plug valve 911 is connected to the oil inlet of the return oil flow sensor 64, the spring chamber of the first two-way plug valve 911 is connected to the P port of the first pilot proportional relief valve 912, the T port of the first pilot proportional relief valve 912 is connected to the oil inlet of the return oil flow sensor 64, and the signal input end of the first pilot proportional relief valve 912 is connected to the signal output end of the controller 5.

[0043] The control valve group 9 further comprises a back pressure proportional relief valve 92, which comprises a second two-way spool valve 921, a second pilot proportional relief valve 922, the A port and the B port of the second two-way spool valve 921 are communicated with the B port of the power recovery motor 4 and the oil tank 7 respectively, the spring cavity of the second two-way spool valve 921 is communicated with the P port of the second pilot proportional relief valve 922, and the T port of the second pilot proportional relief valve 922 is communicated with the oil tank 7.

[0044] The control valve group 9 further comprises a first safety valve 93, which comprises a third two-way spool valve 931, a third pilot proportional relief valve 932, the A port and the B port of the third two-way spool valve 931 are communicated with the oil outlet of the oil supplement pump flow sensor 61 and the oil tank 7 respectively, the spring cavity of the third two-way spool valve 931 is communicated with the P port of the third pilot proportional relief valve 932, the T port of the third pilot proportional relief valve 932 is communicated with the oil tank 7, and the signal input end of the third pilot proportional relief valve 932 is connected with the signal output end of the controller 5.

[0045] The control valve group 9 further comprises a second safety valve 94, which comprises a fourth two-way spool valve 941, a second relief valve 942, the A port and the B port of the fourth two-way spool valve 941 are communicated with the oil outlet of the first one-way valve 32 and the oil inlet of the oil return flow sensor 64 respectively, the spring cavity of the fourth two-way spool valve 941 is communicated with the oil inlet of the second relief valve 942, and the oil outlet of the second relief valve 942 is communicated with the oil inlet of the oil return flow sensor 64.

[0046] The control valve group 9 further comprises a two-way pressure reducing valve 95, which comprises a fifth two-way spool valve 951, a second electromagnetic directional valve 952, a pilot pressure reducing relief valve 953, a fourth pilot proportional relief valve 954, and a third one-way valve 955, the A port of the fifth two-way spool valve 951 is communicated with the oil outlet of the test pump flow sensor group 63, the B port of the fifth two-way spool valve 951 is communicated with the A port of the pilot pressure reducing relief valve 953 and the oil inlet of the third one-way valve 955, the oil outlet of the third one-way valve 955 is communicated with the oil inlet of the power recovery motor flow sensor 62, the spring cavity of the fifth two-way spool valve 951 is communicated with the P port of the second electromagnetic directional valve 952, the B port of the second electromagnetic directional valve 952 is communicated with the P port of the pilot pressure reducing relief valve 953, the X port of the pilot pressure reducing relief valve 953 is communicated with the P port of the fourth pilot proportional relief valve 954, and the T port of the fourth pilot proportional relief valve 954, the T port of the second electromagnetic directional valve 952 and the T port of the pilot pressure reducing relief valve 953 are all communicated with the oil tank 7.

[0047] The oil outlet of the test pump 31 is communicated with the oil inlet of the power recovery motor flow sensor 62 through the second ball valve 34.

[0048] The principle of the present application is explained as follows:

[0049] The main motor 11 is used to drive the oil supplement pump 12 and the control pump 13, the control pump 13 is connected in series behind the oil supplement pump 12, the second one-way valve 123 is used to prevent the reverse flow of oil into the oil supplement pump 12 to cause reverse rotation, the first overflow valve 122 is used to stabilize the outlet pressure of the control pump 13, the variable frequency motor 2 is a double-output shaft motor, the front shaft and the rear shaft are connected with the test pump 31 and the power recovery motor 4 respectively, the variable frequency motor 2 provides the initial starting torque for the test pump 31, and adjusts the rotating speed of the test pump 31 and the power recovery motor 4, the torque speed instrument for measuring the rotating speed and the torque is arranged on the front shaft and the rear shaft of the variable frequency motor 3.

[0050] The oil supplement pump 12 is an electric proportional displacement and hydraulic proportional pressure double-variable hydraulic pump, which comprises a pump body, a variable cylinder 14, a displacement control valve 15 and a pressure control valve 16, the displacement control valve 15 is used to adjust the maximum displacement of the pump body, and the pressure control valve 16 is used to adjust the maximum working pressure of the pump body.

[0051] In order to realize full-flow recovery, the displacement of the test pump 31 and the power recovery motor 4 is equal, and the rotating speed is the same, theoretically, the flow of the test pump 31 and the power recovery motor 4 is equal, considering the volumetric efficiency, the output flow of the test pump 31 is necessarily less than the required flow of the power recovery motor 4, adjusting the rotating speed of the variable frequency motor 10 can adjust the rotating speed of the test pump 31, and adjusting the pressure regulating valve 33 of the test pump can adjust the pressure set value of the test pump 31 itself.

[0052] To prevent the high-pressure port of the power recovery motor 4 from negative pressure, the oil supplement pump 12 is required to be started before the starting variable frequency motor 10 to realize safety protection; the spring force of the right side of the displacement control valve 15 is greater than that of the left side in normal state, so that the displacement control valve 15 works at the right side, A→T, the rodless cavity of the variable cylinder 14 leaks oil through A→T of the displacement control valve 15, and the piston of the variable cylinder 14 is at the leftmost side under the action of the left side spring of the displacement control valve 15, and the oil supplement pump 12 is at the maximum displacement; after the starting of the main motor 11 and the oil supplement pump 12, the pressure oil output by the oil supplement pump 12 enters the rod cavity of the variable cylinder 14, and then enters the rodless cavity of the variable cylinder 14 through the pressure control valve 16 and the displacement control valve 15, when there is no control signal for the pressure control valve 16 and the displacement control valve 15, the pressure control valve 16 and the displacement control valve 15 work at the right side, P→A of the pressure control valve 16 and A→T of the displacement control valve 15, the oil supplement pump 12 is at the minimum displacement state standby, when the displacement control valve 15 has a signal, it works at the left side, and the greater the signal, the greater the P→A opening, and the greater the maximum displacement of the oil supplement pump 12 corresponding to the greater opening; when the output pressure of the oil supplement pump 12 is less than the set value of the pressure control valve 16, the pressure control valve 16 works at the right side, P→A is fully open, so that the oil supplement pump 12 works at the maximum displacement, when the output pressure of the oil supplement pump 12 reaches the set value of the pressure control valve 16, the pressure control valve 16 works at the left side, P→A opening becomes smaller, A→T opening becomes larger, the output flow of the oil supplement pump 12 is adapted to the demand flow of the test system, and the output pressure is unchanged.

[0053] The X2 control port and the X1 control port of the pressure control valve 16 are communicated with the C port of the shuttle valve 17 and the A port of the first electromagnetic reversing valve 19 respectively, since the oil pressure action area of the X1 control port is much larger than that of the X2 control port, the set value of the pressure control valve 16 depends only on the pressure of the X1 port; the proportional pressure reducing valve 18 is used to adjust the pressure of the X1 control port of the pressure control valve 16, and the range is 0.1-3.2 MPa, since the minimum adjustment pressure of the proportional pressure reducing valve 18 is not zero, in order to make the minimum set pressure of the pressure control valve 16 as low as possible to improve the safety and energy saving during the test, the first electromagnetic reversing valve 19 is arranged; when the first electromagnetic reversing valve 19 loses power, the X1 port of the pressure control valve 16 leaks oil through A→L, at this time, the set pressure of the pressure control valve 16 is the lowest, and the oil supplement pump 12 is at low pressure standby, when the first electromagnetic reversing valve 19 is powered and works at the left side, P→A, the set value of the pressure control valve 16 is adjusted through the proportional pressure reducing valve 18.

[0054] The pressure reducing valve 6 is used to provide control oil for the A port of the shuttle valve 17, when the pressure at the oil outlet of the oil supplement pump 12 is less than the set pressure of the pressure reducing valve 121, the shuttle valve 17 is A→C, the hydraulic oil output by the oil supplement pump 12 enters the rod cavity of the variable cylinder 14, so that the oil supplement pump 12 returns to the minimum displacement standby, and energy saving is realized.

[0055] When the electromagnetic reversing valve two of the two-way pressure reducing valve 95 is powered, the frequency conversion motor 10 starts, and the oil at the outlet of the test pump enters the power recovery motor 14 through the ball valve one 17, the test pump flow sensor 18, the two-way pressure reducing valve 95, and the power recovery motor flow sensor 15. The set pressure of the adjusting pilot proportional overflow valve 19.4 can adjust the outlet pressure of the two-way pressure reducing valve 95 to reduce the pressure of the oil entering the power recovery motor to prevent the power recovery motor from being damaged due to overpressure.

[0056] The oil supplement pump flow sensor 61, the power recovery motor flow sensor 62, the test pump flow sensor group 63, and the oil return flow sensor 64 are respectively used to detect the outlet flow q1 of the oil supplement pump 12, the inlet flow q2 of the power recovery motor 4, the outlet flow q3 of the test pump 31, and the outlet flow q4 of the loading proportional overflow valve 91. Since the leakage flow L1 of the two-way pressure reducing valve 95 is very small and can be ignored, q2=q1+q3-q4 can be considered. When the test pump is tested under different rotating speed conditions, since the rotating speed of the power recovery motor 4 is the same as that of the test pump 31, q2 and q3 change synchronously with the rotating speed. The controller 5 adjusts the displacement of the oil supplement pump 12 and the outlet flow q1 through the displacement control valve 15 according to the signals of the flow sensors. When the pressure of each element in the system is synchronously adjusted to match, the outlet flow of the test pump 31 enters the power recovery motor 4, the loading proportional overflow valve 91 has no overflow loss, q4=0, q2=q1+q3, and the oil supplement pump 12 only outputs the difference flow between the test pump 31 and the power recovery motor 4. The system realizes full-flow power recovery.

[0057] The test pump outlet pressure sensor 81, the loading proportional overflow valve inlet pressure sensor 82, the oil supplement pump outlet pressure sensor 83, and the power recovery motor inlet pressure sensor 84 are respectively used to detect the outlet pressure of the test pump 33, the inlet pressure of the loading proportional overflow valve 91, the outlet pressure of the oil supplement pump 12, and the inlet pressure of the power recovery motor 4. When the test pump is tested under different pressure conditions, the controller 5 adjusts the set pressure of the test pump pressure regulating valve 33, the loading proportional overflow valve 91, the proportional pressure reducing valve 18 (the control pressure control valve 16), the first safety valve 93, and the second safety valve 94 according to the signals of the pressure sensors. The outlet pressure of the oil supplement pump 12 is always equal to the set pressure of the test pump pressure regulating valve to prevent the pressure of a certain element from being too low to cause pressure increase. At the same time, the high-pressure oil output by the test pump 31 enters the power recovery motor 4 without overflow loss, and the system realizes full-flow recovery.

[0058] To prevent misoperation or failure caused by the test process of power recovery motor 4 A port pressure is too low, insufficient flow, in the power recovery motor 4 A port is provided with power recovery motor flow sensor 62, when the power recovery motor flow sensor 62 detected pressure signal is lower than the minimum allowable pressure of power recovery motor 4 high pressure port (such as 2.5 MPa), the system stops working and alarms, to prevent the power recovery motor 4 due to low pressure lack of leakage lubrication or suction damage.

[0059] The test pump flow sensor 631, the first ball valve 632 is used for measuring the test pump 33 oil outlet flow, because the test pump 33 oil outlet flow is large, so two test pump flow sensor 631 are connected in parallel, a single test pump flow sensor 631 maximum flow is 600L / min, the maximum total flow (q3) is 1200L / min; in order to improve the measurement accuracy, when the test pump 33 actual test condition oil outlet flow is small, such as total flow ≤0.5×600L / min, the system prompts to close one of the first ball valve 632, otherwise, when the test pump actual test condition oil outlet flow is large, such as total flow ≥0.8×600L / min, the system prompts two first ball valve 632 are opened, to prevent the test pump flow sensor 631 damage, when the total flow ≥0.9×600L / min, the system alarm stop.

[0060] The two-way pressure reducing valve 95 is used for reducing the pressure of the test pump 33 output high pressure oil before entering the power recovery motor 4, and the set pressure can be adjusted steplessly. Because the overload test pressure of the test pump 33 is greater than the rated pressure of the power recovery motor 4, it is necessary to reduce the pressure of the oil entering the power recovery motor 4 to prevent the power recovery motor 4 from being damaged by overpressure.

[0061] The two-way pressure reducing valve 95 mainly includes a fifth two-way plug valve 951, a second electromagnetic reversing valve 952, a pilot pressure reducing relief valve 953, and a fourth pilot proportional relief valve 954. The fifth two-way plug valve 951 is a main-stage pressure reducing element, and the second electromagnetic reversing valve 952 is used to control the on-off of the fifth two-way plug valve 951. When the second electromagnetic reversing valve 952 loses power, the oil in the spring chamber at the top of the fifth two-way plug valve 951 is closed. Since the oil pressure and the effective area at the top and bottom are the same, the fifth two-way plug valve 951 is self-locked and closed under the action of the spring. When the second electromagnetic reversing valve 952 loses power, the oil in the spring chamber at the top of the fifth two-way plug valve 951 is closed. When valve 952 is energized P→B, the oil in the top spring chamber of the fifth two-way plug valve 951 flows to the P port of the pilot pressure-reducing relief valve 953. Since the pilot pressure-reducing relief valve 953 is normally open, the flow of oil causes the oil pressure in the top spring chamber of the fifth two-way plug valve 951 to be lower than the oil pressure at the bottom, causing the fifth two-way plug valve 951 to open, and having a pressure-reducing effect from A→B. At the same time, the X port of the pilot pressure-reducing relief valve 953 flows to the P port of the fourth pilot proportional relief valve 954, adjusting the pressure of the fourth pilot proportional relief valve 954, and then adjusting the opening and outlet pressure of the fifth two-way plug valve 951.

[0062] The test pump pressure regulating valve 33 is used to remotely and steplessly adjust the pressure setting value of the test pump to keep the operator away from high-pressure oil.

[0063] The second ball valve 34 is used to open when a component fails, so that the high-pressure oil output by the test pump 33 can directly enter the power recovery motor 4, and the system can still work for a short time.

[0064] The back pressure proportional relief valve 92 is used to adjust the outlet pressure of the power recovery motor 4, providing a stable oil return back pressure for the power recovery motor 4, making the power recovery motor rotate more smoothly, and meeting the minimum working pressure requirement of the low pressure port of the power recovery motor.

[0065] Example 1:

[0066] See also Figures 1 to 7 A dual-variable hydraulic pump power recovery test system includes an oil charging pump group 1, a variable frequency motor 2, a test pump group 3, a power recovery motor 4, a controller 5, a flow regulating valve group 6, an oil tank 7, a pressure regulating valve group 8, and a control valve group 9. The test pump group 3 includes a test pump 31, a first one-way valve 32, and a test pump pressure regulating valve 33 installed on the test pump 31. The flow regulating valve group 6 includes an oil charging pump flow sensor 61, a power recovery motor flow sensor 62, a test pump flow sensor group 63, and a return oil flow sensor 64. The pressure regulating valve group 8 includes a test pump outlet pressure sensor 81, a loading proportional relief valve inlet pressure sensor 82, an oil charging pump outlet pressure sensor 83, and a power recovery motor inlet pressure sensor 84. The control valve group 9 includes a loading proportional relief valve 91.

[0067] The variable frequency motor 2 is in transmission cooperation with the test pump 31, the power recovery motor 4, the oil inlet of the test pump 31 is communicated with the oil tank 7, the oil outlet of the test pump 31 is communicated with the oil inlet of the test pump flow sensor group 63 through the first one-way valve 32, the oil outlet of the test pump flow sensor group 63 is communicated with the oil inlet of the power recovery motor flow sensor 62 and the oil inlet of the loading proportional overflow valve 91, the oil outlet of the loading proportional overflow valve 91 is communicated with the oil tank 7 through the oil return flow sensor 64, the oil outlet of the power recovery motor flow sensor 62 is communicated with the A port of the power recovery motor 4, the B port of the power recovery motor 4 is communicated with the oil tank 7;

[0068] The oil supplement pump group 1 includes a main motor 11, an oil supplement pump 12, a control pump 13, a variable cylinder 14, a displacement control valve 15, a pressure control valve 16, a shuttle valve 17, a proportional pressure reducing valve 18, a first electromagnetic reversing valve 19, a pressure reducing valve 121, a first overflow valve 122 and a second one-way valve 123, the main motor 11 is in transmission cooperation with the oil supplement pump 12 and the control pump 13, the oil inlets of the oil supplement pump 12 and the control pump 13 are communicated with the oil tank 7, the oil outlet of the oil supplement pump 12 is communicated with the oil inlet of the second one-way valve 123 and the B port of the shuttle valve 17, the oil outlet of the second one-way valve 123 is communicated with the oil inlet of the power recovery motor flow sensor 62 through the oil supplement pump flow sensor 61, the oil outlet of the control pump 13 is communicated with the oil inlets of the pressure reducing valve 121, the proportional pressure reducing valve 18 and the first overflow valve 122, the oil outlet of the pressure reducing valve 121 is communicated with the A port of the shuttle valve 17, the C port of the shuttle valve 17 is communicated with the rod cavity of the variable cylinder 14, the P port of the pressure control valve 16 and the X2 port of the pressure control valve 16, the rodless cavity of the variable cylinder 14 is communicated with the A port of the displacement control valve 15, the T port and the P port of the displacement control valve 15 are respectively communicated with the oil tank 7 and the A port of the pressure control valve 16, the T port and the X1 port of the pressure control valve 16 are respectively communicated with the oil tank 7 and the A port of the first electromagnetic reversing valve 19, the P port of the first electromagnetic reversing valve 19 is communicated with the oil outlet of the proportional pressure reducing valve 18, the L port of the first electromagnetic reversing valve 19 and the oil outlet of the first overflow valve 122 are both communicated with the oil tank 7;

[0069] The test pump outlet pressure sensor 81 is arranged near the oil outlet of the first one-way valve 32, the loading proportional overflow valve inlet pressure sensor 82 is arranged near the oil outlet of the test pump flow sensor group 63, the oil supplement pump outlet pressure sensor 83 is arranged between the oil outlet of the second one-way valve 123 and the oil inlet of the oil supplement pump flow sensor 61, and the power recovery motor inlet pressure sensor 84 is arranged between the oil outlet of the power recovery motor flow sensor 62 and the A port of the power recovery motor 4;

[0070] When testing different speed conditions of the test pump 31, the controller 5 adjusts the set pressures of the test pump pressure regulating valve 33, the charge pump group 1, and the load proportional relief valve 91 in a closed loop according to the pressure signals of the test pump outlet pressure sensor 81, the load proportional relief valve inlet pressure sensor 82, the charge pump outlet pressure sensor 83, and the power recovery motor inlet pressure sensor 84;

[0071] When testing different pressure conditions of the test pump 31, the set pressures of the proportional pressure reducing valve 18 and the displacement control valve 15 on the charge pump group 1 are adjusted in a closed loop by the controller 5 according to the flow signals of the power recovery motor flow sensor 62, the test pump flow sensor group 63, the return oil flow sensor 64, and the charge pump flow sensor 61.

[0072] Example 2:

[0073] The difference from Example 1 is that:

[0074] The test pump flow sensor group 63 includes two parallel test pump flow sensors 631, and a first ball valve 632 is connected in series at the oil inlet of the test pump flow sensor 631. The oil outlets of the two test pump flow sensors 631 together constitute the oil outlet of the test pump flow sensor group 63, and the oil inlets of the two first ball valves 632 together constitute the oil inlet of the test pump flow sensor group 63.

[0075] Example 3:

[0076] The difference from Example 1 is that:

[0077] The loading proportional relief valve 91 includes a first two-way plug valve 911 and a first pilot proportional relief valve 912. The A port of the first two-way plug valve 911 is connected to the oil outlet of the test pump flow sensor group 63, the B port of the first two-way plug valve 911 is connected to the oil inlet of the return oil flow sensor 64, the spring chamber of the first two-way plug valve 911 is connected to the P port of the first pilot proportional relief valve 912, the T port of the first pilot proportional relief valve 912 is connected to the oil inlet of the return oil flow sensor 64, and the signal input end of the first pilot proportional relief valve 912 is connected to the signal output end of the controller 5.

[0078] Example 4:

[0079] The difference from Example 1 is that:

[0080] The control valve group 9 further comprises a back pressure proportional relief valve 92 and a two-way pressure reducing valve 95. The back pressure proportional relief valve 92 comprises a second two-way spool valve 921 and a second pilot proportional relief valve 922. The A port and the B port of the second two-way spool valve 921 are respectively communicated with the B port of the power recovery motor 4 and the oil tank 7. The spring cavity of the second two-way spool valve 921 is communicated with the P port of the second pilot proportional relief valve 922. The T port of the second pilot proportional relief valve 922 is communicated with the oil tank 7. The two-way pressure reducing valve 95 comprises a fifth two-way spool valve 951, a second electromagnetic directional valve 952, a pilot pressure reducing relief valve 953, a fourth pilot proportional relief valve 954 and a third check valve 955. The A port of the fifth two-way spool valve 951 is communicated with the oil outlet of the test pump flow sensor group 63. The B port of the fifth two-way spool valve 951 is communicated with the A port of the pilot pressure reducing relief valve 953 and the oil inlet of the third check valve 955. The oil outlet of the third check valve 955 is communicated with the oil inlet of the power recovery motor flow sensor 62. The spring cavity of the fifth two-way spool valve 951 is communicated with the P port of the second electromagnetic directional valve 952. The B port of the second electromagnetic directional valve 952 is communicated with the P port of the pilot pressure reducing relief valve 953. The X port of the pilot pressure reducing relief valve 953 is communicated with the P port of the fourth pilot proportional relief valve 954. The T port of the fourth pilot proportional relief valve 954, the T port of the second electromagnetic directional valve 952 and the T port of the pilot pressure reducing relief valve 953 are all communicated with the oil tank 7.

[0081] Embodiment 5:

[0082] The difference from embodiment 4 is that:

[0083] The control valve group 9 further comprises a first safety valve 93 and a second safety valve 94. The first safety valve 93 comprises a third two-way spool valve 931 and a third pilot proportional relief valve 932. The A port and the B port of the third two-way spool valve 931 are respectively communicated with the oil outlet of the oil supplement pump flow sensor 61 and the oil tank 7. The spring cavity of the third two-way spool valve 931 is communicated with the P port of the third pilot proportional relief valve 932. The T port of the third pilot proportional relief valve 932 is communicated with the oil tank 7. The second safety valve 94 comprises a fourth two-way spool valve 941 and a second relief valve 942. The A port and the B port of the fourth two-way spool valve 941 are respectively communicated with the oil outlet of the first check valve 32 and the oil inlet of the oil return flow sensor 64. The spring cavity of the fourth two-way spool valve 941 is communicated with the oil inlet of the second relief valve 942. The oil outlet of the second relief valve 942 is communicated with the oil inlet of the oil return flow sensor 64.

[0084] Embodiment 6:

[0085] The difference from embodiment 1 is that:

[0086] The oil outlet of the test pump 31 is communicated with the oil inlet of the power recovery motor flow sensor 62 through the second ball valve 34.

Claims

1. A dual variable hydraulic pump power recovery test system characterized in that: The test system comprises an oil supplement pump set (1), a variable frequency motor (2), a test pump set (3), a power recovery motor (4), a controller (5), a flow regulating valve set (6), an oil tank (7), the flow regulating valve set (6) comprises an oil supplement pump flow sensor (61), a power recovery motor flow sensor (62), a test pump flow sensor set (63), an oil return flow sensor (64), the variable frequency motor (2) is in driving cooperation with the test pump set (3) and the power recovery motor (4), the oil outlet of the test pump set (3) is in communication with the oil inlet of the test pump flow sensor set (63), the oil outlet of the test pump flow sensor set (63) is in communication with the oil inlet of the power recovery motor flow sensor (62) and the oil inlet of the oil return flow sensor (64), the oil outlet of the oil return flow sensor (64) is in communication with the oil tank (7), the oil outlet of the power recovery motor flow sensor (62) is in communication with the A port of the power recovery motor (4), the B port of the power recovery motor (4) is in communication with the oil tank (7), and the oil outlet of the oil supplement pump set (1) is in communication with the oil inlet of the power recovery motor flow sensor (62) through the oil supplement pump flow sensor (61); The signal input end of the controller (5) is connected with the signal output ends of the power recovery motor flow sensor (62), the test pump flow sensor set (63), the oil return flow sensor (64) and the oil supplement pump flow sensor (61), and the signal output end of the controller (5) is connected with the signal input end of the oil supplement pump set (1). The oil supplement pump group (1) comprises a main motor (11), an oil supplement pump (12), a control pump (13), a variable cylinder (14), a displacement control valve (15), a pressure control valve (16), a shuttle valve (17), a proportional pressure reducing valve (18), a first electromagnetic reversing valve (19), a pressure reducing valve (121), a first overflow valve (122), and a second check valve (123). The main motor (11) is in driving cooperation with the oil supplement pump (12) and the control pump (13). The oil inlets of the oil supplement pump (12) and the control pump (13) are communicated with an oil tank (7). The oil outlet of the oil supplement pump (12) is communicated with the oil inlet of the second check valve (123) and the B port of the shuttle valve (17). The oil outlet of the second check valve (123) is communicated with the oil inlet of an oil supplement pump flow sensor (61). The oil outlet of the control pump (13) is communicated with the oil inlets of the pressure reducing valve (121), the proportional pressure reducing valve (18), and the first overflow valve (122). The oil outlet of the pressure reducing valve (121) is communicated with the A port of the shuttle valve (17). The C port of the shuttle valve (17) is communicated with the rod cavity of the variable cylinder (14), the P port of the pressure control valve (16), and the X (2) port of the pressure control valve (16). The rodless cavity of the variable cylinder (14) is communicated with the A port of the displacement control valve (15). The T port and the P port of the displacement control valve (15) are respectively communicated with the oil tank (7) and the A port of the pressure control valve (16). The T port and the X (1) port of the pressure control valve (16) are respectively communicated with the oil tank (7) and the A port of the first electromagnetic reversing valve (19). The P port of the first electromagnetic reversing valve (19) is communicated with the oil outlet of the proportional pressure reducing valve (18). The L port of the first electromagnetic reversing valve (19) and the oil outlet of the first overflow valve (122) are both communicated with the oil tank (7). The signal output end of the controller (5) is connected with the signal input ends of the proportional pressure reducing valve (18) and the displacement control valve (15).

2. The dual-variable hydraulic pump power recovery test system according to claim 1, characterized in that: The test pump group (3) comprises a test pump (31), a first check valve (32), and a test pump pressure regulating valve (33) installed on the test pump (31). The test system further comprises a pressure regulating valve group (8) and a control valve group (9). The pressure regulating valve group (8) comprises a test pump outlet pressure sensor (81), a loading proportional overflow valve inlet pressure sensor (82), an oil supplement pump outlet pressure sensor (83), and a power recovery motor inlet pressure sensor (84). The control valve group (9) comprises a loading proportional overflow valve (91). The oil inlet of the test pump (31) is communicated with the oil tank (7), the oil outlet of the test pump (31) is communicated with the oil inlet of the test pump flow sensor group (63) through the first check valve (32), the test pump outlet pressure sensor (81) is arranged near the oil outlet of the first check valve (32), the loading proportional overflow valve inlet pressure sensor (82) is arranged near the oil outlet of the test pump flow sensor group (63), the oil supplement pump outlet pressure sensor (83) is arranged between the oil outlet of the oil supplement pump group (1) and the oil inlet of the oil supplement pump flow sensor (61), the power recovery motor inlet pressure sensor (84) is arranged between the oil outlet of the power recovery motor flow sensor (62) and the A port of the power recovery motor (4), the oil inlet and the oil outlet of the loading proportional overflow valve (91) are communicated with the oil outlet of the test pump flow sensor group (63) and the oil inlet of the return oil flow sensor (64) respectively. The signal input end of the controller (5) is connected with the signal output end of the test pump outlet pressure sensor (81), the loading proportional overflow valve inlet pressure sensor (82), the oil supplement pump outlet pressure sensor (83) and the power recovery motor inlet pressure sensor (84), and the signal output end of the controller (5) is connected with the signal input end of the test pump pressure regulating valve (33), the oil supplement pump group (1) and the loading proportional overflow valve (91).

3. The bi-variable hydraulic pump power recovery test system according to claim 1 or 2, characterized in that: The test pump flow sensor group (63) comprises two parallel test pump flow sensors (631), the oil inlet of the test pump flow sensor (631) is connected with the first ball valve (632) in series, the oil outlets of the two test pump flow sensors (631) jointly form the oil outlet of the test pump flow sensor group (63), and the oil inlets of the two first ball valves (632) jointly form the oil inlet of the test pump flow sensor group (63).

4. The dual variable hydraulic pump power recovery test system of claim 2, wherein: The loading proportional overflow valve (91) comprises a first two-way plug valve (911) and a first pilot proportional overflow valve (912), the A port of the first two-way plug valve (911) is communicated with the oil outlet of the test pump flow sensor group (63), the B port of the first two-way plug valve (911) is communicated with the oil inlet of the return oil flow sensor (64), the spring cavity of the first two-way plug valve (911) is communicated with the P port of the first pilot proportional overflow valve (912), the T port of the first pilot proportional overflow valve (912) is communicated with the oil inlet of the return oil flow sensor (64), and the signal input end of the first pilot proportional overflow valve (912) is connected with the signal output end of the controller (5).

5. A dual variable hydraulic pump power recovery test system as set forth in claim 2, characterized by: The control valve group (9) further comprises a back pressure proportional overflow valve (92), the back pressure proportional overflow valve (92) comprises a second two-way plug valve (921) and a second pilot proportional overflow valve (922), the A port and the B port of the second two-way plug valve (921) are communicated with the B port of the power recovery motor (4) and the oil tank (7) respectively, the spring cavity of the second two-way plug valve (921) is communicated with the P port of the second pilot proportional overflow valve (922), and the T port of the second pilot proportional overflow valve (922) is communicated with the oil tank (7).

6. The dual variable hydraulic pump power recovery test system of claim 2 or 5, wherein: The control valve group (9) further comprises a first safety valve (93), the first safety valve (93) comprises a third two-way plug valve (931) and a third pilot proportional overflow valve (932), the A port and the B port of the third two-way plug valve (931) are communicated with the oil outlet of the oil pump flow sensor (61) and the oil tank (7) respectively, the spring cavity of the third two-way plug valve (931) is communicated with the P port of the third pilot proportional overflow valve (932), the T port of the third pilot proportional overflow valve (932) is communicated with the oil tank (7), and the signal input end of the third pilot proportional overflow valve (932) is connected with the signal output end of the controller (5).

7. The dual variable hydraulic pump power recovery test system of claim 2 or 5, wherein: The control valve group (9) further comprises a second safety valve (94), the second safety valve (94) comprises a fourth two-way plug valve (941) and a second overflow valve (942), the A port and the B port of the fourth two-way plug valve (941) are communicated with the oil outlet of the first one-way valve (32) and the oil inlet of the oil return flow sensor (64) respectively, the spring cavity of the fourth two-way plug valve (941) is communicated with the oil inlet of the second overflow valve (942), and the oil outlet of the second overflow valve (942) is communicated with the oil inlet of the oil return flow sensor (64).

8. The dual variable hydraulic pump power recovery test system of claim 2 or 5, wherein: The control valve group (9) further comprises a two-way pressure reducing valve (95), the two-way pressure reducing valve (95) comprises a fifth two-way plug valve (951), a second electromagnetic directional valve (952), a pilot pressure reducing overflow valve (953), a fourth pilot proportional overflow valve (954) and a third one-way valve (955), the A port of the fifth two-way plug valve (951) is communicated with the oil outlet of the test pump flow sensor group (63), the B port of the fifth two-way plug valve (951) is communicated with the A port of the pilot pressure reducing overflow valve (953) and the oil inlet of the third one-way valve (955), the oil outlet of the third one-way valve (955) is communicated with the oil inlet of the power recovery motor flow sensor (62), the spring cavity of the fifth two-way plug valve (951) is communicated with the P port of the second electromagnetic directional valve (952), the B port of the second electromagnetic directional valve (952) is communicated with the P port of the pilot pressure reducing overflow valve (953), the X port of the pilot pressure reducing overflow valve (953) is communicated with the P port of the fourth pilot proportional overflow valve (954), and the T port of the fourth pilot proportional overflow valve (954), the T port of the second electromagnetic directional valve (952) and the T port of the pilot pressure reducing overflow valve (953) are all communicated with the oil tank (7).

9. The dual variable hydraulic pump power recovery test system according to claim 2, characterized in that: The oil outlet of the test pump (31) is communicated with the oil inlet of the power recovery motor flow sensor (62) through the second ball valve (34).

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