A hydraulic pump and hydraulic motor test system and its test method

Abstract

In a hydraulic pump and hydraulic motor test system, a first gear, a second gear, and a fifth gear are respectively sleeved on the first shaft, the second shaft, and the fifth shaft of the gearbox. The two sides of the second gear are respectively meshed with the first gear and the fifth gear. The fourth shaft is coaxially fixed with the fifth shaft. A third gear is sleeved on the third shaft, and the third gear is meshed with a fourth gear sleeved on the first shaft. When testing the hydraulic pump, the first shaft, the second shaft, and the third shaft are respectively in transmission cooperation with a variable-frequency motor, the hydraulic pump under test, and a power recovery hydraulic motor. When testing the hydraulic motor for forward rotation, the second shaft and the fourth shaft are respectively in transmission cooperation with a power recovery hydraulic pump and the hydraulic motor under test. When testing the hydraulic motor for reverse rotation, the second shaft and the fifth shaft are respectively in transmission cooperation with a power recovery hydraulic pump and the hydraulic motor under test. This design can complete the endurance tests of hydraulic motors and hydraulic pumps through a set of test systems and has a high degree of integration.

Description

Technical Field

[0001] The present invention belongs to the technical field of durability tests for hydraulic systems, and particularly relates to a test system and a test method for a hydraulic pump and a hydraulic motor, which are applicable to completing power recovery for durability tests of two types of hydraulic motors and hydraulic pumps using the same set of test system, with high integration. Background Art

[0002] Durability tests are an important part of the type tests for hydraulic pumps and motors. According to relevant standards, the full-load durability test time requirement for a hydraulic pump is 2400 h, the full-load durability test time requirement for a hydraulic motor is 1000 h (500 h each for forward and reverse rotations of a two-way motor), the impact test is 100,000 times, and the overload test is 10 h. Due to the long test time, in order to save energy and reduce consumption, a mechanical power recovery test system is often used, that is, the power of the test element is recovered through a gearbox, a variable-frequency motor, and a power recovery element. When the test element is a hydraulic pump, the high-pressure oil output by the hydraulic pump enters the power recovery hydraulic motor, and the hydraulic motor drives the test hydraulic pump together with the gearbox and the variable-frequency motor to achieve power recovery. When the test element is a hydraulic motor, a hydraulic pump is used for loading, the high-pressure oil output by the hydraulic pump enters the test hydraulic motor, and the test hydraulic motor drives the hydraulic pump together with the gearbox and the variable-frequency motor to achieve power recovery. The existing test system cannot test both a hydraulic motor and a hydraulic pump first. Moreover, since the rotational speed, pressure, and displacement of the test element and the power recovery element are required to match, when testing multiple different types of elements, if separate gearboxes are required for matching, not only is the test system complex, occupies a large space, but also the price is expensive. Therefore, the existing test system has the problem that the same set of test system cannot perform two types of tests on hydraulic pumps and hydraulic motors, and the integration is poor. Summary of the Invention

[0003] The object of the present invention is to overcome the above problems existing in the prior art, and provide a test system and a test method for a hydraulic pump and a hydraulic motor that can test both a hydraulic motor and a hydraulic pump.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A test system for a hydraulic pump and a hydraulic motor, the test system includes a gearbox, a variable-frequency motor, a hydraulic pump, a hydraulic motor, a makeup oil pump, and an electric machine. The inlet ports of the hydraulic pump and the makeup oil pump are both connected to a fuel tank, and the outlet ports of the hydraulic pump and the makeup oil pump are both connected to the fuel tank through the hydraulic motor. The hydraulic pump is a test hydraulic pump or a power recovery hydraulic pump, and the hydraulic motor is a power recovery hydraulic motor or a test hydraulic motor;

[0006] The gearbox includes a box body, a first shaft, a second shaft, a third shaft, a fourth shaft, and a fifth shaft installed inside the box body. The first shaft, the second shaft, and the fifth shaft are arranged side by side. A first gear, a second gear, and a fifth gear are respectively sleeved on the first shaft, the second shaft, and the fifth shaft. The two sides of the second gear are respectively meshed with the first gear and the fifth gear. The fourth shaft and the fifth shaft are coaxially fixed, and the fourth shaft and the third shaft are arranged side by side. A third gear is sleeved on the third shaft, and the third gear is meshed with a fourth gear sleeved on the first shaft. The first shaft can be in transmission cooperation with a variable-frequency motor, the second shaft can be in transmission cooperation with a hydraulic pump under test or a power recovery hydraulic pump, the third shaft can be in transmission cooperation with a power recovery hydraulic motor, the fourth shaft and the fifth shaft can be in transmission cooperation with a hydraulic motor under test, and the motor supplies energy to the make-up oil pump.

[0007] The ratio n1:n2 of the rotational speed n1 of the first shaft to the rotational speed n2 of the second shaft is 1:1. The ratio n3:n2 of the rotational speed n3 of the third shaft to the rotational speed n2 of the second shaft is 4:5. The ratio n4:n2 of the rotational speed n4 of the fourth shaft to the rotational speed n2 of the second shaft is 4:3. The ratio n5:n2 of the rotational speed n5 of the fifth shaft to the rotational speed n2 of the second shaft is 4:3.

[0008] The gearbox further includes a sixth shaft, a seventh shaft, an eighth shaft, and a ninth shaft. The sixth shaft and the seventh shaft are coaxially fixed. A sixth gear, a seventh gear, and an eighth gear are respectively sleeved on the sixth shaft, the seventh shaft, and the eighth shaft. The top and bottom of the sixth gear are respectively meshed with the seventh gear and the second gear, and the eighth gear is meshed with the first gear.

[0009] The ratio n6:n2 of the rotational speed n6 of the sixth shaft to the rotational speed n2 of the second shaft is 2:1. The ratio n7:n2 of the rotational speed n7 of the seventh shaft to the rotational speed n2 of the second shaft is 2:1. The ratio n1:n9 of the rotational speed n1 of the first shaft to the rotational speed n9 of the ninth shaft is 1:1. The ratio n8:n7 of the rotational speed n8 of the eighth shaft to the rotational speed n7 of the seventh shaft is 1:4.

[0010] The test system further includes a proportional relief valve. The oil outlet of the hydraulic pump is also connected to the oil tank through the proportional relief valve.

[0011] The oil outlet of the hydraulic motor is successively connected to the oil tank through a cooler and a filter.

[0012] The ratio n1:n2 of the rotational speed n1 of the first shaft to the rotational speed n2 of the second shaft is 1:1. The ratio n3:n2 of the rotational speed n3 of the third shaft to the rotational speed n2 of the second shaft is 4:5. The ratio n4:n2 of the rotational speed n4 of the fourth shaft to the rotational speed n2 of the second shaft is 4:3. The ratio n5:n2 of the rotational speed n5 of the fifth shaft to the rotational speed n2 of the second shaft is 4:3;

[0013] The test method includes a hydraulic pump test with a displacement of 500 mL / r and a hydraulic motor test with a displacement of 500 mL / r. The specific process of the hydraulic pump test with a displacement of 500 mL / r is as follows: Taking the hydraulic pump with a displacement of 500 mL / r as the tested hydraulic pump, first, the first shaft, the second shaft, and the third shaft are respectively in transmission cooperation with the variable-frequency motor, the tested hydraulic pump, and the power recovery hydraulic motor. Then, drive the variable-frequency motor to drive the tested hydraulic pump to work. The high-pressure oil output by the tested hydraulic pump enters the power recovery hydraulic motor, and the power recovery hydraulic motor and the variable-frequency motor jointly drive the tested hydraulic pump through the gearbox to achieve power recovery.

[0014] The hydraulic motor test with a displacement of 500 mL / r includes a forward rotation test and a reverse rotation test on the hydraulic motor with a displacement of 500 mL / r. The specific process of the forward rotation test on the hydraulic motor with a displacement of 500 mL / r is as follows: Taking the hydraulic motor with a displacement of 500 mL / r rotating forward as the tested hydraulic motor, first, the second shaft and the fourth shaft are respectively in transmission cooperation with the power recovery hydraulic pump and the tested hydraulic motor. Then, use the makeup oil pump to supply oil to the tested hydraulic motor and provide the initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through the gearbox, and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery.

[0015] The specific process of the reverse rotation test on the hydraulic motor with a displacement of 500 mL / r is as follows: Taking the hydraulic motor with a displacement of 500 mL / r rotating in reverse as the tested hydraulic motor, first, the second shaft and the fifth shaft are respectively in transmission cooperation with the power recovery hydraulic pump and the tested hydraulic motor. Then, use the makeup oil pump to supply oil to the tested hydraulic motor and provide the initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through the gearbox, and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery.

[0016] The gearbox further includes a sixth shaft, a seventh shaft, an eighth shaft, and a ninth shaft. A sixth gear, a seventh gear, and an eighth gear are respectively sleeved on the sixth shaft, the eighth shaft, and the ninth shaft. The top and bottom of the sixth gear are respectively meshed with the seventh gear and the second gear. The eighth gear is meshed with the first gear. The ratio of the rotational speed n6 of the sixth shaft to the rotational speed n2 of the second shaft, n6:n2, is 2:1. The ratio of the rotational speed n7 of the seventh shaft to the rotational speed n2 of the second shaft, n7:n2, is 2:1. The ratio of the rotational speed n1 of the first shaft to the rotational speed n9 of the ninth shaft, n1:n9, is 1:1. The ratio of the rotational speed n8 of the eighth shaft to the rotational speed n7 of the seventh shaft, n8:n7, is 1:4.

[0017] The test method further includes a test on a hydraulic motor with a displacement of 355 mL / r. The test on the hydraulic motor with a displacement of 355 mL / r includes testing the hydraulic motor with a displacement of 355 mL / r under the pump condition and testing the hydraulic motor with a displacement of 355 mL / r under the motor condition;

[0018] The specific process of testing the hydraulic motor with a displacement of 355 mL / r under the pump condition is as follows: Taking the hydraulic motor with a displacement of 355 mL / r as the tested hydraulic pump, first, the first shaft, the ninth shaft, and the eighth shaft are respectively in transmission cooperation with the variable-frequency motor, the tested hydraulic pump, and the power recovery hydraulic motor. Then, the variable-frequency motor is driven to drive the tested hydraulic pump to work. The high-pressure oil output by the tested hydraulic pump enters the power recovery hydraulic motor. The power recovery hydraulic motor and the variable-frequency motor jointly drive the tested hydraulic pump through a gearbox to achieve power recovery;

[0019] The test on the hydraulic motor with a displacement of 355 mL / r under the motor condition includes a forward rotation test on the hydraulic motor with a displacement of 355 mL / r under the motor condition and a reverse rotation test on the hydraulic motor with a displacement of 355 mL / r under the motor condition. The specific process of the forward rotation test on the hydraulic motor with a displacement of 355 mL / r under the motor condition is as follows: Taking the hydraulic motor with a displacement of 355 mL / r rotating forward as the tested hydraulic motor, first, the second shaft and the sixth shaft are respectively in transmission cooperation with the power recovery hydraulic pump and the tested hydraulic motor. Then, the make-up oil pump is used to supply oil to the tested hydraulic motor and provide an initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through a gearbox. The power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery;

[0020] The specific process of the reverse rotation test on the hydraulic motor with a displacement of 355 mL / r under the motor condition is as follows: Taking the hydraulic motor with a displacement of 355 mL / r rotating in reverse as the tested hydraulic motor, first, the second shaft and the seventh shaft are respectively in transmission cooperation with the power recovery hydraulic pump and the tested hydraulic motor. Then, the make-up oil pump is used to supply oil to the tested hydraulic motor and provide an initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through a gearbox. The power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. A hydraulic pump and hydraulic motor test system of the present invention includes a gearbox, a variable-frequency motor, a hydraulic pump, a hydraulic motor, a makeup oil pump, and a motor. The inlet ports of the hydraulic pump and the makeup oil pump are both connected to the fuel tank, and the outlet ports of the hydraulic pump and the makeup oil pump are both connected to the fuel tank through the hydraulic motor. The hydraulic pump is a hydraulic pump to be tested or a power recovery hydraulic pump, and the hydraulic motor is a power recovery hydraulic motor or a hydraulic motor to be tested. The gearbox includes a box body, a first shaft, a second shaft, a third shaft, a fourth shaft, and a fifth shaft installed inside the box body. The first shaft, the second shaft, and the fifth shaft are arranged side by side. A first gear, a second gear, and a fifth gear are respectively sleeved on the first shaft, the second shaft, and the fifth shaft. The two sides of the second gear are respectively meshed with the first gear and the fifth gear. The fourth shaft is coaxially fixed with the fifth shaft, the fourth shaft and the third shaft are arranged side by side, and a third gear is sleeved on the third shaft. The third gear is meshed with a fourth gear sleeved on the first shaft. For the hydraulic pump test, first, the first shaft, the second shaft, and the third shaft are respectively in transmission cooperation with the variable-frequency motor, the hydraulic pump to be tested, and the power recovery hydraulic motor, and then the variable-frequency motor is driven to drive the hydraulic pump to be tested to work. The high-pressure oil output by the hydraulic pump to be tested enters the power recovery hydraulic motor, and the power recovery hydraulic motor and the variable-frequency motor drive the hydraulic pump to be tested through the gearbox to achieve power recovery. For the hydraulic motor test, the hydraulic motor test includes a forward rotation test and a reverse rotation test. During the forward rotation test, first, the second shaft and the fourth shaft are respectively in transmission cooperation with the power recovery hydraulic pump and the hydraulic motor to be tested, and then the makeup oil pump is used to supply oil to the hydraulic motor to be tested and provide an initial starting torque. The hydraulic motor to be tested drives the power recovery hydraulic pump through the gearbox, and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor to be tested to achieve power recovery. During the reverse rotation test, first, the second shaft and the fifth shaft are respectively in transmission cooperation with the power recovery hydraulic pump and the hydraulic motor to be tested, and then the makeup oil pump is used to supply oil to the hydraulic motor to be tested and provide an initial starting torque. The hydraulic motor to be tested drives the power recovery hydraulic pump through the gearbox, and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor to be tested to achieve power recovery. The design of the present invention has high integration, small occupied space, and low cost. Therefore, the present invention completes the endurance tests of the hydraulic motor and the hydraulic pump through the same test system, and the system has high integration, small occupied space, and low cost.

[0023] 2. In a test system for a hydraulic pump and a hydraulic motor according to the present invention, the gearbox includes a box body, a first shaft, a second shaft, a third shaft, a fourth shaft, and a fifth shaft installed inside the box body. The first shaft, the second shaft, and the fifth shaft are arranged side by side. A first gear, a second gear, and a fifth gear are respectively sleeved on the first shaft, the second shaft, and the fifth shaft. The two sides of the second gear are respectively meshed with the first gear and the fifth gear. The fourth shaft and the fifth shaft are coaxially fixed, the fourth shaft and the third shaft are arranged side by side, and a third gear is sleeved on the third shaft. The third gear is meshed with a fourth gear sleeved on the first gear. For the hydraulic pump to be tested, first, the first shaft, the ninth shaft, and the eighth shaft are respectively in transmission cooperation with a variable-frequency motor, the hydraulic pump to be tested, and a power recovery hydraulic motor. Then, the variable-frequency motor is driven to drive the hydraulic pump to be tested to work. The high-pressure oil output by the hydraulic pump to be tested enters the power recovery hydraulic motor. The power recovery hydraulic motor and the variable-frequency motor jointly drive the hydraulic pump to be tested through the gearbox to achieve power recovery. For the forward rotation test of the hydraulic motor to be tested, first, the second shaft and the sixth shaft are respectively in transmission cooperation with a power recovery hydraulic pump and the hydraulic motor to be tested. Then, an oil supply pump is used to supply oil to the hydraulic motor to be tested and provide an initial starting torque. The hydraulic motor to be tested drives the power recovery hydraulic pump through the gearbox, and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor to be tested to achieve power recovery. For the reverse rotation test of the hydraulic motor to be tested, first, the second shaft and the seventh shaft are respectively in transmission cooperation with a power recovery hydraulic pump and the hydraulic motor to be tested. Then, an oil supply pump is used to supply oil to the hydraulic motor to be tested and provide an initial starting torque. The hydraulic motor to be tested drives the power recovery hydraulic pump through the gearbox, and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor to be tested to achieve power recovery. Through the installation of different shaft extensions on the same gearbox, the rotational speed matching of hydraulic pumps and hydraulic motors of different models is realized on the same gearbox, and the system has high versatility. Therefore, the present invention realizes the rotational speed matching of hydraulic pumps and hydraulic motors of different models and has high versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the principle of the test system in the present invention.

[0025] Figure 2 is a schematic diagram of the structure of the gearbox in the present invention.

[0026] Figure 3 is Figure 2 a sectional view taken along the A-A direction of

[0027] Figure 4 is Figure 2 a sectional view taken along the B-B direction of

[0028] Figure 5 is a schematic diagram of the rotational speed ratio of each shaft of the gearbox in the embodiment.

[0029] Figure 6Assembly drawing for the 500 mL / r hydraulic pump test in the embodiment.

[0030] Figure 7 Assembly drawing for the forward rotation test of the 500 mL / r motor in the embodiment.

[0031] Figure 8 Assembly drawing for the reverse rotation test of the 500 mL / r motor in the embodiment.

[0032] Figure 9 Assembly drawing for the test of the 355 mL / r motor in pump condition in the embodiment.

[0033] Figure 10 Assembly drawing for the test of the 355 mL / r motor in motor condition and forward rotation in the embodiment.

[0034] Figure 11 Assembly drawing for the test of the 355 mL / r motor in motor condition and reverse rotation in the embodiment.

[0035] In the figure, there are gearbox 1, first shaft 11, first gear 111, fourth gear 112, second shaft 12, second gear 121, third shaft 13, third gear 131, fourth shaft 14, fifth shaft 15, fifth gear 151, sixth shaft 16, sixth gear 161, seventh shaft 17, eighth shaft 18, seventh gear 181, ninth shaft 19, eighth gear 191, variable frequency motor 2, hydraulic pump 3, hydraulic motor 4, makeup oil pump 5, motor 6, proportional relief valve 7, cooler 8, filter 9. Specific implementation manners

[0036] The present invention will be further described below in conjunction with the accompanying drawings of the specification and specific implementation manners.

[0037] Refer to Figures 1 to 11 , a hydraulic pump and hydraulic motor test system, the test system includes gearbox 1, variable frequency motor 2, hydraulic pump 3, hydraulic motor 4, makeup oil pump 5, motor 6, the inlet ports of the hydraulic pump 3 and the makeup oil pump 5 are both communicated with the fuel tank 7, the outlet ports of the hydraulic pump 3 and the makeup oil pump 5 are both communicated with the fuel tank 7 through the hydraulic motor 4, the hydraulic pump 3 is a hydraulic pump to be tested or a power recovery hydraulic pump, and the hydraulic motor 4 is a power recovery hydraulic motor or a hydraulic motor to be tested;

[0038] The gearbox 1 includes a box body, a first shaft 11, a second shaft 12, a third shaft 13, a fourth shaft 14, and a fifth shaft 15 installed inside the box body. The first shaft 11, the second shaft 12, and the fifth shaft 15 are arranged side by side. A first gear 111, a second gear 121, and a fifth gear 151 are respectively sleeved on the first shaft 11, the second shaft 12, and the fifth shaft 15. Both sides of the second gear 121 are meshed with the first gear 111 and the fifth gear 151 respectively. The fourth shaft 14 and the fifth shaft 15 are coaxially fixed, and the fourth shaft 14 and the third shaft 13 are arranged side by side. A third gear 131 is sleeved on the third shaft 13, and the third gear 131 is meshed with a fourth gear 112 sleeved on the first shaft 11. The first shaft 11 can be in transmission cooperation with a variable-frequency motor 2. The second shaft 12 can be in transmission cooperation with a hydraulic pump under test or a power recovery hydraulic pump. The third shaft 13 can be in transmission cooperation with a power recovery hydraulic motor. The fourth shaft 14 and the fifth shaft 15 can be in transmission cooperation with a hydraulic motor under test. The motor 6 supplies energy to the make-up oil pump 5.

[0039] The ratio n1:n2 of the rotational speed n1 of the first shaft 11 to the rotational speed n2 of the second shaft 12 is 1:1. The ratio n3:n2 of the rotational speed n3 of the third shaft 13 to the rotational speed n2 of the second shaft 12 is 4:5. The ratio n4:n2 of the rotational speed n4 of the fourth shaft 14 to the rotational speed n2 of the second shaft 12 is 4:3. The ratio n5:n2 of the rotational speed n5 of the fifth shaft 15 to the rotational speed n2 of the second shaft 12 is 4:3.

[0040] The gearbox 1 further includes a sixth shaft 16, a seventh shaft 17, an eighth shaft 18, and a ninth shaft 19. The sixth shaft 16 and the seventh shaft 17 are coaxially fixed. A sixth gear 161, a seventh gear 181, and an eighth gear 191 are respectively sleeved on the sixth shaft 16, the eighth shaft 18, and the ninth shaft 19. The top and bottom of the sixth gear 161 are respectively meshed with the seventh gear 181 and the second gear 121. The eighth gear 191 is meshed with the first gear 111.

[0041] The ratio n6:n2 of the rotational speed n6 of the sixth shaft 16 to the rotational speed n2 of the second shaft 12 is 2:1. The ratio n7:n2 of the rotational speed n7 of the seventh shaft 17 to the rotational speed n2 of the second shaft 12 is 2:1. The ratio n1:n9 of the rotational speed n1 of the first shaft 11 to the rotational speed n9 of the ninth shaft 19 is 1:1. The ratio n8:n7 of the rotational speed n8 of the eighth shaft 18 to the rotational speed n7 of the seventh shaft 17 is 1:4.

[0042] The test system further includes a proportional overflow valve 8. The oil outlet of the hydraulic pump 3 is also connected to the oil tank 7 through the proportional overflow valve 8.

[0043] The oil outlet of the hydraulic motor 4 is sequentially connected to the oil tank 7 through a cooler 9 and a filter 10.

[0044] A test method for a hydraulic pump and a hydraulic motor test system, wherein the ratio of the speed n1 of the first shaft 11 to the speed n2 of the second shaft 12 is 1:1, the ratio of the speed n3 of the third shaft 13 to the speed n2 of the second shaft 12 is 4:5, the ratio of the speed n4 of the fourth shaft 14 to the speed n2 of the second shaft 12 is 4:3, and the ratio of the speed n5 of the fifth shaft 15 to the speed n2 of the second shaft 12 is 4:3.

[0045] The test method includes a 500mL / r displacement hydraulic pump test and a 500mL / r displacement hydraulic motor test. The 500mL / r displacement hydraulic pump test is specifically as follows: a 500mL / r displacement hydraulic pump is used as a tested hydraulic pump. The first shaft 11, the second shaft 12, and the third shaft 13 are respectively matched with the variable frequency motor 2, the tested hydraulic pump, and the power recovery hydraulic motor. Then, the variable frequency motor 2 is driven to drive the tested hydraulic pump to work. The high-pressure oil output by the tested hydraulic pump enters the power recovery hydraulic motor. The power recovery hydraulic motor drives the tested hydraulic pump through the gear box 1 and the variable frequency motor 2 to achieve power recovery.

[0046] The 500mL / r displacement hydraulic motor test includes a forward rotation test and a reverse rotation test of the 500mL / r displacement hydraulic motor. The forward rotation test of the 500mL / r displacement hydraulic motor is specifically as follows: the 500mL / r displacement hydraulic motor is used as the tested hydraulic motor, the second shaft 12 and the fourth shaft 14 are respectively matched with the power recovery hydraulic pump and the tested hydraulic motor, and then the supplementary oil pump 5 is used to supply oil to the tested hydraulic motor and provide initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through the gear box 1, and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery;

[0047] The reversal test of the 500mL / r displacement hydraulic motor is specifically as follows: taking the 500mL / r displacement hydraulic motor as the tested hydraulic motor, firstly the second shaft 12 and the fifth shaft 15 are respectively matched with the power recovery hydraulic pump and the tested hydraulic motor transmission, and then the oil replenishment pump 5 is used to supply oil to the tested hydraulic motor and provide the initial starting torque, the tested hydraulic motor drives the power recovery hydraulic pump through the gear box 1, and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to realize power recovery.

[0048] The gearbox 1 further includes a sixth shaft 16, a seventh shaft 17, an eighth shaft 18, and a ninth shaft 19. Sixth gears 161, seventh gears 181, and eighth gears 191 are respectively sleeved on the sixth shaft 16, the eighth shaft 18, and the ninth shaft 19. The top and bottom of the sixth gear 161 are respectively meshed with the seventh gear 181 and the second gear 121. The eighth gear 191 is meshed with the first gear 111. The ratio n6:n2 of the rotational speed n6 of the sixth shaft 16 to the rotational speed n2 of the second shaft 12 is 2:1. The ratio n7:n2 of the rotational speed n7 of the seventh shaft 17 to the rotational speed n2 of the second shaft 12 is 2:1. The ratio n1:n9 of the rotational speed n1 of the first shaft 11 to the rotational speed n9 of the ninth shaft 19 is 1:1. The ratio n8:n7 of the rotational speed n8 of the eighth shaft 18 to the rotational speed n7 of the seventh shaft 17 is 1:4;

[0049] The test method further includes a test on a hydraulic motor with a displacement of 355 mL / r. The test on the hydraulic motor with a displacement of 355 mL / r includes testing the hydraulic motor with a displacement of 355 mL / r under the pump condition and testing the hydraulic motor with a displacement of 355 mL / r under the motor condition;

[0050] The specific operation of testing the hydraulic motor with a displacement of 355 mL / r under the pump condition is as follows: Using the hydraulic motor with a displacement of 355 mL / r as the tested hydraulic pump, first, the first shaft 11, the ninth shaft 19, and the eighth shaft 18 are respectively in transmission cooperation with the variable-frequency motor 2, the tested hydraulic pump, and the power recovery hydraulic motor. Then, the variable-frequency motor 2 is driven to drive the tested hydraulic pump to work. The high-pressure oil output by the tested hydraulic pump enters the power recovery hydraulic motor. The power recovery hydraulic motor and the gearbox 1 jointly drive the tested hydraulic pump with the variable-frequency motor 2 to achieve power recovery;

[0051] The test on the hydraulic motor with a displacement of 355 mL / r under the motor condition includes a forward rotation test on the hydraulic motor with a displacement of 355 mL / r under the motor condition and a reverse rotation test on the hydraulic motor with a displacement of 355 mL / r under the motor condition. The specific operation of the forward rotation test on the hydraulic motor with a displacement of 355 mL / r under the motor condition is as follows: Using the hydraulic motor with a displacement of 355 mL / r as the tested hydraulic motor, first, the second shaft 12 and the sixth shaft 16 are respectively in transmission cooperation with the power recovery hydraulic pump and the tested hydraulic motor. Then, the make-up oil pump 5 is used to supply oil to the tested hydraulic motor and provide an initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through the gearbox 1. The power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery;

[0052] The reverse test of the hydraulic motor with a displacement of 355 mL / r under the motor condition is specifically as follows: Taking the hydraulic motor with a displacement of 355 mL / r as the tested hydraulic motor, first, the second shaft 12 and the seventh shaft 17 are respectively in transmission cooperation with the power recovery hydraulic pump and the tested hydraulic motor. Then, the make-up oil pump 5 is used to supply oil to the tested hydraulic motor and provide the initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through the gearbox 1, and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery.

[0053] The principle of the present invention is described as follows:

[0054] The gearbox in the hydraulic pump and hydraulic motor test system of the present invention is the core of the test system. A plurality of connecting shaft extensions are provided on the gearbox, which are respectively used to connect the variable-frequency motor, the tested hydraulic pump / power recovery hydraulic pump, and the tested hydraulic motor / power recovery hydraulic motor, and transmit the recovered power, so as to realize the endurance test of two types of hydraulic pumps and hydraulic motors. The system has high integration, small occupied space, and low cost.

[0055] The variable-frequency motor is used to adjust the speed of the tested hydraulic pump or the tested hydraulic motor and provide the initial starting torque of the tested pump. After the tested hydraulic pump starts, the power recovery motor and the variable-frequency motor drive the tested pump together.

[0056] Both the hydraulic pump and the hydraulic motor can be used as the tested components or power recovery components respectively. When the hydraulic pump is the tested component, the hydraulic motor is the power recovery component; when the hydraulic motor is the tested component, the hydraulic pump is the power recovery component; when the tested component is the hydraulic pump, the high-pressure oil output by the hydraulic pump enters the power recovery hydraulic motor, and the hydraulic motor drives the tested hydraulic pump together with the variable-frequency motor through the gearbox to achieve power recovery. When the tested component is the hydraulic motor, the hydraulic pump is used for loading. The high-pressure oil output by the hydraulic pump enters the tested hydraulic motor, and the tested hydraulic motor drives the hydraulic pump together with the variable-frequency motor through the gearbox to achieve power recovery. During the test, first start the make-up oil motor pump group to provide the initial oil source for the tested hydraulic motor. The tested hydraulic motor drives the power recovery hydraulic pump to rotate through the gearbox, and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery.

[0057] Embodiment:

[0058] See Figures 1 to 5, a hydraulic pump and hydraulic motor test system, which includes a gearbox 1, a variable-frequency motor 2, a hydraulic pump 3, a hydraulic motor 4, a makeup oil pump 5, a motor 6, and a proportional overflow valve 8. The inlet ports of the hydraulic pump 3 and the makeup oil pump 5 are both connected to a fuel tank 7. The outlet ports of the hydraulic pump 3 and the makeup oil pump 5 are respectively connected to the inlet port of the hydraulic motor 4 through a first one-way valve and a second one-way valve. The outlet port of the hydraulic motor 4 is sequentially connected to the fuel tank 7 through a cooler 9 and a filter 10. The outlet port of the hydraulic pump 3 is also connected to the inlet port of the cooler 9 through the proportional overflow valve 8. Between the hydraulic pump 3 and the fuel tank 7, there is also a connection through a parallel combination of a proportional overflow valve and an electromagnetic directional valve. Between the makeup oil pump 5 and the fuel tank 7, there is also a connection through a parallel combination of a proportional overflow valve and an electromagnetic directional valve;

[0059] The gearbox 1 includes a box body, a first shaft 11, a second shaft 12, a third shaft 13, a fourth shaft 14, a fifth shaft 15, a sixth shaft 16, a seventh shaft 17, an eighth shaft 18, and a ninth shaft 19 installed inside the box body. The first shaft 11, the second shaft 12, and the fifth shaft 15 are arranged side by side. A first gear 111, a second gear 121, and a fifth gear 151 are respectively sleeved on the first shaft 11, the second shaft 12, and the fifth shaft 15. Both sides of the second gear 121 are meshed with the first gear 111 and the fifth gear 151 respectively. The fourth shaft 14 is coaxially fixed to the fifth shaft 15, and the fourth shaft 14 and the third shaft 13 are arranged side by side. A third gear 131 is sleeved on the third shaft 13, and the third gear 131 is meshed with a fourth gear 112 sleeved on the first shaft 11. The sixth shaft 16 is coaxially fixed to the seventh shaft 17. A sixth gear 161, a seventh gear 181, and an eighth gear 191 are respectively sleeved on the sixth shaft 16, the eighth shaft 18, and the ninth shaft 19. The top and bottom of the sixth gear 161 are respectively meshed with the seventh gear 181 and the second gear 121, and the eighth gear 191 is meshed with the first gear 111;

[0060] The ratio n1:n2 of the rotational speed n1 of the first shaft 11 to the rotational speed n2 of the second shaft 12 is 1:1. The ratio n3:n2 of the rotational speed n3 of the third shaft 13 to the rotational speed n2 of the second shaft 12 is 4:5. The ratio n4:n2 of the rotational speed n4 of the fourth shaft 14 to the rotational speed n2 of the second shaft 12 is 4:3. The ratio n5:n2 of the rotational speed n5 of the fifth shaft 15 to the rotational speed n2 of the second shaft 12 is 4:3. The ratio n6:n2 of the rotational speed n6 of the sixth shaft 16 to the rotational speed n2 of the second shaft 12 is 2:1. The ratio n7:n2 of the rotational speed n7 of the seventh shaft 17 to the rotational speed n2 of the second shaft 12 is 2:1. The ratio n1:n9 of the rotational speed n1 of the first shaft 11 to the rotational speed n9 of the ninth shaft 19 is 1:1. The ratio n8:n7 of the rotational speed n8 of the eighth shaft 18 to the rotational speed n7 of the seventh shaft 17 is 1:4;

[0061] A test method based on the above hydraulic pump and hydraulic motor test system, using a 500 mL / r hydraulic pump, a 500 mL / r hydraulic motor, and a 355 mL / r hydraulic motor as test objects respectively, conducts the following tests:

[0062] I. Parameters of the test component

[0063] Table 1 Parameters of the test component

[0064] .

[0065] II. 500 mL / r hydraulic pump

[0066] Refer to Figure 6 , use a hydraulic pump with a displacement of 500 mL / r as the test hydraulic pump. First, respectively drive the first shaft 11, the second shaft 12, and the third shaft 13 to be in transmission cooperation with the variable-frequency motor 2, the test hydraulic pump, and the power recovery hydraulic motor. Then drive the variable-frequency motor 2 to drive the test hydraulic pump to work. The high-pressure oil output by the test hydraulic pump enters the power recovery hydraulic motor. The power recovery hydraulic motor and the variable-frequency motor 2 jointly drive the test hydraulic pump through the gearbox 1 to achieve power recovery;

[0067] Under the rated speed condition, the rotational speed of the variable-frequency motor 2 is 1500 rpm, the rotational speed of the test hydraulic pump is 1500 rpm, and the rotational speed of the power recovery motor is 1200 rpm. The volumetric efficiencies of the test hydraulic pump and the power recovery motor are both considered as 0.95. The output flow of the test hydraulic pump is 500 mL / r × 1500 rpm × 0.95 = 712.5 L / min. Most of its output flow enters the power recovery hydraulic motor. The recovered flow of the power recovery hydraulic motor is 500 mL / r × 1200 rpm / 0.95 = 631.6 L / min, and the recovery rate is 88.6%;

[0068] Under the overspeed condition, the rotational speed of the variable-frequency motor 2 is 1800 rpm, the rotational speed of the test hydraulic pump is 1800 rpm, and the rotational speed of the power recovery motor is 1440 rpm. The volumetric efficiencies of the test hydraulic pump and the power recovery motor are both considered as 0.95. The output flow of the test hydraulic pump is 500 mL / r × 1800 rpm × 0.95 = 855 L / min. Most of its output flow enters the power recovery hydraulic motor. The recovered flow of the power recovery hydraulic motor is 500 mL / r × 1440 rpm / 0.95 = 757.9 L / min, and the recovery rate is 88.6%;

[0069] III. 500 mL / r motor

[0070] 1. 500 mL / r motor forward rotation

[0071] Refer to Figure 7, using a hydraulic motor with a displacement of 500 mL / r rotating in the forward direction as the hydraulic motor under test. First, the second shaft 12 and the fourth shaft 14 are respectively in transmission cooperation with the power recovery hydraulic pump and the hydraulic motor under test. Then, the make-up oil pump 5 is used to supply oil to the hydraulic motor under test and provide the initial starting torque. The hydraulic motor under test drives the power recovery hydraulic pump through the gearbox 1, and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor under test to achieve power recovery;

[0072] The rotational speed of the hydraulic motor under test is 2000 rpm, and the rotational speed of the power recovery hydraulic pump is 1500 rpm. The volumetric efficiencies of the hydraulic motor under test and the power recovery hydraulic pump are both considered as 0.95. The required flow rate of the hydraulic motor under test is 500 mL / r × 2000 rpm / 0.95 = 1052.6 L / min, the output flow rate of the power recovery hydraulic pump is 500 mL / r × 1500 rpm × 0.95 = 712.5 L / min, and the recovery rate is 67.7%;

[0073] 2. 500 mL / r motor rotates in reverse

[0074] See Figure 8 , using a hydraulic motor with a displacement of 500 mL / r rotating in the reverse direction as the hydraulic motor under test. The second shaft 12 and the fifth shaft 15 are respectively in transmission cooperation with the power recovery hydraulic pump and the hydraulic motor under test. All other conditions are the same as those in the forward rotation test of the 500 mL / r motor;

[0075] IV. 355 mL / r motor

[0076] 1. 355 mL / r motor is in pump condition

[0077] See Figure 9 , using a hydraulic motor with a displacement of 355 mL / r in pump condition as the hydraulic pump under test. First, the first shaft 11, the ninth shaft 19, and the eighth shaft 18 are respectively in transmission cooperation with the variable-frequency motor 2, the hydraulic pump under test, and the power recovery hydraulic motor. Then, the variable-frequency motor 2 is driven to drive the hydraulic pump under test to work. The high-pressure oil output by the hydraulic pump under test enters the power recovery hydraulic motor, and the power recovery hydraulic motor and the variable-frequency motor 2 jointly drive the hydraulic pump under test through the gearbox 1 to achieve power recovery;

[0078] At the rated speed condition, the rotational speed of the variable-frequency motor 2 is 2000 rpm, the rotational speed of the hydraulic pump under test is 2000 rpm, and the rotational speed of the power recovery hydraulic motor is 1000 rpm. The volumetric efficiencies of the hydraulic pump under test and the power recovery hydraulic motor are both considered as 0.95. The output flow rate of the hydraulic pump under test is 355 mL / r × 2000 rpm × 0.95 = 674.5 L / min. Most of its output flow enters the power recovery hydraulic motor. The recovered flow rate of the power recovery hydraulic motor is 500 mL / r × 1000 rpm / 0.95 = 526.3 L / min, and the recovery rate is 78.0%;

[0079] At the overspeed condition, the rotational speed of the variable-frequency motor 2 is 2200 rpm, the rotational speed of the hydraulic pump under test is 2200 rpm (at this time, the motor displacement is 0.8 × 355 mL / r), and the rotational speed of the power recovery hydraulic motor is 1100 rpm. The volumetric efficiencies of the hydraulic pump under test and the power recovery hydraulic motor are both considered as 0.95. The output flow rate of the hydraulic pump under test is 0.8 × 355 mL / r × 2200 rpm × 0.95 = 593.6 L / min. Most of the output flow of the hydraulic pump under test enters the power recovery hydraulic motor. The recovered flow rate is 500 mL / r × 1100 rpm / 0.95 = 578.9 L / min, and the recovery rate is 97.5%;

[0080] 2. The 355 mL / r motor is in the motor condition and rotates forward

[0081] See Figure 10 , taking the 355 mL / r displacement hydraulic motor in the motor condition and rotating forward as the hydraulic motor under test. First, the second shaft 12 and the sixth shaft 16 are respectively in transmission cooperation with the power recovery hydraulic pump and the hydraulic motor under test. Then, the make-up oil pump 5 is used to supply oil to the hydraulic motor under test and provide the initial starting torque. The hydraulic motor under test drives the power recovery hydraulic pump through the gearbox 1, and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor under test to achieve power recovery;

[0082] At the rated speed condition, the rotational speed of the hydraulic motor under test is 2000 rpm, and the rotational speed of the power recovery hydraulic pump is 1000 rpm. The hydraulic motor under test and the power recovery hydraulic pump are both considered as 0.95. The required flow rate of the motor under test is 355 mL / r × 2000 rpm / 0.95 = 747.4 L / min. The output flow rate of the power recovery hydraulic pump is 500 mL / r × 1000 rpm × 0.95 = 526.3 L / min, and the recovery rate is 70.4%;

[0083] In the overspeed condition, the rotational speed of the test hydraulic motor is 2200 rpm (at this time, the motor displacement is 0.8×355 mL / r), and the rotational speed of the power recovery hydraulic pump is 1100 rpm. The volumetric efficiencies of the test hydraulic motor and the power recovery hydraulic pump are both considered as 0.95. The required flow rate of the test hydraulic motor is 0.8×355 mL / r×2200 rpm / 0.95 = 657.7 L / min, the output flow rate of the power recovery hydraulic pump is 500 mL / r×1100 rpm / 0.95 = 578.9 L / min, and the recovery rate is 88.0%.

[0084] 3. The 355 mL / r motor is in the motor condition and rotates reversely

[0085] Refer to Figure 11 , use the 355 mL / r displacement hydraulic motor in the motor condition and rotating reversely as the test hydraulic motor, drive and cooperate the second shaft 12 and the seventh shaft 17 with the power recovery hydraulic pump and the test hydraulic motor respectively, and other conditions are the same as those in the test of the 355 mL / r motor in the motor condition and rotating forward.

Claims

1. A hydraulic pump and hydraulic motor test system, characterized in that: The test system includes a gearbox (1), a variable-frequency motor (2), a hydraulic pump (3), a hydraulic motor (4), a makeup oil pump (5), and a motor (6). The inlet ports of the hydraulic pump (3) and the makeup oil pump (5) are both connected to a fuel tank (7). The outlet ports of the hydraulic pump (3) and the makeup oil pump (5) are both connected to the fuel tank (7) through the hydraulic motor (4). The hydraulic pump (3) is a hydraulic pump to be tested or a power recovery hydraulic pump, and the hydraulic motor (4) is a power recovery hydraulic motor or a hydraulic motor to be tested; The gearbox (1) includes a box body, a first shaft (11), a second shaft (12), a third shaft (13), a fourth shaft (14), and a fifth shaft (15) installed inside the box body. The first shaft (11), the second shaft (12), and the fifth shaft (15) are arranged side by side. A first gear (111), a second gear (121), and a fifth gear (151) are respectively sleeved on the first shaft (11), the second shaft (12), and the fifth shaft (15). Both sides of the second gear (121) are meshed with the first gear (111) and the fifth gear (151) respectively. The fourth shaft (14) and the fifth shaft (15) are coaxially fixed, and the fourth shaft (14) and the third shaft (13) are arranged side by side. A third gear (131) is sleeved on the third shaft (13), and the third gear (131) is meshed with a fourth gear (112) sleeved on the first shaft (11). The first shaft (11) can be in transmission cooperation with the variable-frequency motor (2). The second shaft (12) can be in transmission cooperation with a hydraulic pump to be tested or a power recovery hydraulic pump. The third shaft (13) can be in transmission cooperation with a power recovery hydraulic motor. The fourth shaft (14) and the fifth shaft (15) can be in transmission cooperation with a hydraulic motor to be tested. The motor (6) supplies energy to the makeup oil pump (5).

2. The hydraulic pump and hydraulic motor test system according to claim 1, characterized in that: The ratio n1:n2 of the rotational speed n1 of the first shaft (11) to the rotational speed n2 of the second shaft (12) is 1:

1. The ratio n3:n2 of the rotational speed n3 of the third shaft (13) to the rotational speed n2 of the second shaft (12) is 4:

5. The ratio n4:n2 of the rotational speed n4 of the fourth shaft (14) to the rotational speed n2 of the second shaft (12) is 4:

3. The ratio n5:n2 of the rotational speed n5 of the fifth shaft (15) to the rotational speed n2 of the second shaft (12) is 4:

3.

3. The hydraulic pump and hydraulic motor test system according to claim 2, wherein: The gearbox (1) further includes a sixth shaft (16), a seventh shaft (17), an eighth shaft (18), and a ninth shaft (19). The sixth shaft (16) and the seventh shaft (17) are coaxially fixed. A sixth gear (161), a seventh gear (181), and an eighth gear (191) are respectively sleeved on the sixth shaft (16), the eighth shaft (18), and the ninth shaft (19). The top and bottom of the sixth gear (161) are respectively meshed with the seventh gear (181) and the second gear (121). The eighth gear (191) is meshed with the first gear (111).

4. A hydraulic pump and hydraulic motor test system according to claim 3, characterized in that: The ratio of the sixth shaft (16) rotational speed n6 to the second shaft (12) rotational speed n2 is n6:n2, which is 2:1; the ratio of the seventh shaft (17) rotational speed n7 to the second shaft (12) rotational speed n2 is n7:n2, which is 2:1; the ratio of the first shaft (11) rotational speed n1 to the ninth shaft (19) rotational speed n9 is n1:n9, which is 1:1; and the ratio of the eighth shaft (18) rotational speed n8 to the seventh shaft (17) rotational speed n7 is n8:n7, which is 1:

4.

5. A hydraulic pump and hydraulic motor test system according to any one of claims 1-4, characterized in that: The test system further comprises a proportional relief valve 8, and the oil outlet of the hydraulic pump (3) is also connected to the oil tank (7) via the proportional relief valve 8.

6. A hydraulic pump and hydraulic motor test system according to any one of claims 1-4, characterized in that: The oil outlet of the hydraulic motor (4) is connected to the oil tank (7) via a cooler 9 and a filter 10 in sequence.

7. The test method of a hydraulic pump and hydraulic motor test system according to claim 1, characterized in that: The ratio n1:n2 of the speed n1 of the first shaft (11) to the speed n2 of the second shaft (12) is 1:1, the ratio n3:n2 of the speed n3 of the third shaft (13) to the speed n2 of the second shaft (12) is 4:5, the ratio n4:n2 of the speed n4 of the fourth shaft (14) to the speed n2 of the second shaft (12) is 4:3, and the ratio n5:n2 of the speed n5 of the fifth shaft (15) to the speed n2 of the second shaft (12) is 4:3; The test method includes a 500mL / r displacement hydraulic pump test and a 500mL / r displacement hydraulic motor test. The 500mL / r displacement hydraulic pump test specifically includes: using a 500mL / r displacement hydraulic pump as a tested hydraulic pump, firstly, the first shaft (11), the second shaft (12), and the third shaft (13) are respectively matched with the variable frequency motor (2), the tested hydraulic pump, and the power recovery hydraulic motor for transmission, and then the variable frequency motor (2) is driven to drive the tested hydraulic pump to work, and the high-pressure oil output by the tested hydraulic pump enters the power recovery hydraulic motor, and the power recovery hydraulic motor drives the tested hydraulic pump through the gear box (1) and the variable frequency motor (2) to achieve power recovery; The 500mL / r displacement hydraulic motor test includes a forward rotation test and a reverse rotation test of the 500mL / r displacement hydraulic motor. The forward rotation test of the 500mL / r displacement hydraulic motor is specifically as follows: the forward rotation 500mL / r displacement hydraulic motor is used as the tested hydraulic motor, the second shaft (12) and the fourth shaft (14) are respectively matched with the power recovery hydraulic pump and the tested hydraulic motor, and then the supplementary oil pump (5) is used to supply oil to the tested hydraulic motor and provide an initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through the gear box (1), and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery. The reverse test on the hydraulic motor with a displacement of 500 mL / r is specifically as follows: The hydraulic motor with a displacement of 500 mL / r in reverse is used as the tested hydraulic motor. First, the second shaft (12) and the fifth shaft (15) are respectively in transmission cooperation with the power recovery hydraulic pump and the tested hydraulic motor. Then, the make-up oil pump (5) is used to supply oil to the tested hydraulic motor and provide the initial starting torque. The tested hydraulic motor drives the power recovery hydraulic pump through the gearbox (1), and the power recovery hydraulic pump also outputs high-pressure oil into the tested hydraulic motor to achieve power recovery.

8. The test method of a hydraulic pump and hydraulic motor test system according to claim 7, characterized in that: The gearbox (1) further includes a sixth shaft (16), a seventh shaft (17), an eighth shaft (18), and a ninth shaft (19). Sixth gears (161), seventh gears (181), and eighth gears (191) are respectively sleeved on the sixth shaft (16), the eighth shaft (18), and the ninth shaft (19). The top and bottom of the sixth gear (161) are respectively meshed with the seventh gear (181) and the second gear (121). The eighth gear (191) is meshed with the first gear (111). The ratio n6:n2 of the rotational speed n6 of the sixth shaft (16) to the rotational speed n2 of the second shaft (12) is 2:

1. The ratio n7:n2 of the rotational speed n7 of the seventh shaft (17) to the rotational speed n2 of the second shaft (12) is 2:

1. The ratio n1:n9 of the rotational speed n1 of the first shaft (11) to the rotational speed n9 of the ninth shaft (19) is 1:

1. The ratio n8:n7 of the rotational speed n8 of the eighth shaft (18) to the rotational speed n7 of the seventh shaft (17) is 1:

4. The test method further includes a test on a hydraulic motor with a displacement of 355 mL / r. The test on the hydraulic motor with a displacement of 355 mL / r includes a test on the hydraulic motor with a displacement of 355 mL / r under the pump condition and a test on the hydraulic motor with a displacement of 355 mL / r under the motor condition. The test on the hydraulic motor with a displacement of 355 mL / r under the pump condition is specifically as follows: The hydraulic motor with a displacement of 355 mL / r is used as the tested hydraulic pump. First, the first shaft (11), the ninth shaft (19), and the eighth shaft (18) are respectively in transmission cooperation with the frequency conversion motor (2), the tested hydraulic pump, and the power recovery hydraulic motor. Then, the frequency conversion motor (2) is driven to drive the tested hydraulic pump to work. The high-pressure oil output by the tested hydraulic pump enters the power recovery hydraulic motor. The power recovery hydraulic motor and the frequency conversion motor (2) jointly drive the tested hydraulic pump through the gearbox (1) to achieve power recovery. The test on the 355 mL / r displacement hydraulic motor under the motor condition includes a forward rotation test on the 355 mL / r displacement hydraulic motor under the motor condition and a reverse rotation test on the 355 mL / r displacement hydraulic motor under the motor condition. The specific steps for the forward rotation test on the 355 mL / r displacement hydraulic motor under the motor condition are as follows: Using the forward rotation 355 mL / r displacement hydraulic motor as the hydraulic motor to be tested, first, the second shaft (12) and the sixth shaft (16) are respectively in transmission cooperation with the power recovery hydraulic pump and the hydraulic motor to be tested. Then, the make-up oil pump (5) is used to supply oil to the hydraulic motor to be tested and provide the initial starting torque. The hydraulic motor to be tested drives the power recovery hydraulic pump through the gearbox (1), and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor to be tested to achieve power recovery. The specific steps for the reverse rotation test on the 355 mL / r displacement hydraulic motor under the motor condition are as follows: Using the reverse rotation 355 mL / r displacement hydraulic motor as the hydraulic motor to be tested, first, the second shaft (12) and the seventh shaft (17) are respectively in transmission cooperation with the power recovery hydraulic pump and the hydraulic motor to be tested. Then, the make-up oil pump (5) is used to supply oil to the hydraulic motor to be tested and provide the initial starting torque. The hydraulic motor to be tested drives the power recovery hydraulic pump through the gearbox (1), and the power recovery hydraulic pump also outputs high-pressure oil into the hydraulic motor to be tested to achieve power recovery.

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