A hydraulic system for automatic leveling test bench

Abstract

A hydraulic system for an automatic leveling test bench, wherein four supporting hydraulic cylinders are connected to the lower support frame; the piston rod of the supporting hydraulic cylinder is fixedly connected to the bearing disc; four connecting steel pipes are hinged at the lower part of the upper support frame, and every two connecting steel pipes are fixedly connected to the two ends of the upper crossbeam, and the end of the upper crossbeam is fixedly connected to the sliding shoe provided on the bearing disc through supporting bolts; the horizontal inclination sensor is installed in the middle of the upper frame; the controller is respectively connected to the four supporting hydraulic cylinders through four electromagnetic proportional reversing valves, and is also respectively connected to the leveling hydraulic cylinder through four electromagnetic proportional reversing valves; a displacement sensor is arranged on the supporting hydraulic cylinder, and a hydraulically controlled reversing valve and a variable throttle valve are arranged on the oil circuit where the rodless cavity of the supporting hydraulic cylinder is located; a displacement sensor and a speed sensor are arranged on the leveling hydraulic cylinder. The system can simulate various road surface unevenness, and can simulate different vehicle travel speeds, and can verify the leveling effect in real time during the test.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural machinery testing equipment, and in particular relates to a hydraulic system for an automatic leveling test bench. Background Art

[0002] In recent years, with the development of automatic leveling technology, it has been widely used in the fields of engineering machinery and agricultural machinery, effectively improving the passability and driving comfort of the machine. In agricultural machinery, the automatic leveling function is often achieved by installing hydraulic suspension, so that the agricultural machinery can automatically level the frame on uneven roads to better adapt to hilly and mountainous terrain operations.

[0003] Because hydraulic suspension needs to be adjusted in real time, it is easy to cause a series of problems such as high heat generation and slow response of the hydraulic system, and it may even cause the whole machine to malfunction. There is an urgent need for a test bench to test and analyze the leveling system to improve R&D efficiency and reduce R&D costs. However, the automatic leveling system lacks effective testing methods because the road spectrum is difficult to simulate and the testing cost is high. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a hydraulic system for an automatic leveling test bench, which can simulate various road unevenness and different vehicle running speeds, and at the same time, can verify the effect of the leveling hydraulic suspension in real time during the test.

[0005] In order to achieve the above-mentioned object, the present invention provides a hydraulic system for an automatic leveling test bench, comprising an automatic leveling test bench, a hydraulic control system and a controller;

[0006] The automatic leveling test bench includes a lower support frame, four upper support plates, four support hydraulic cylinders, four load-bearing discs, an upper leveling mechanism, a top support beam a and a horizontal inclination sensor; the lower support frame is composed of a lower frame and four support legs of equal length, the lower frame is composed of two lower cross beams a correspondingly distributed front and rear and two lower cross beams b correspondingly distributed left and right, which are fixedly connected in sequence, and the upper ends of the four support legs are respectively fixedly connected to the four corners of the lower end of the lower frame; the four upper support plates are respectively fixedly connected to the four corners of the upper end of the lower frame, and the centers of the four upper support plates are all provided with through holes A; the four support hydraulic cylinders are respectively recorded as support hydraulic cylinder A, support hydraulic cylinder B, support hydraulic cylinder C and support hydraulic cylinder D; the four support hydraulic cylinders are respectively recorded as support hydraulic cylinder A, support hydraulic cylinder B, support hydraulic cylinder C and support hydraulic cylinder D; The pressure cylinders are respectively arranged at the lower parts of the four upper support plates, and the lower ends of the supporting hydraulic cylinder barrels are all located above the lower ends of the support legs; the upper ends of the four supporting hydraulic cylinder barrels are respectively fixedly connected to the lower end surfaces of the four upper support plates, and the piston rods of the four supporting hydraulic cylinders slide through the through holes A on the four upper support plates, and are respectively fixedly connected to the four connecting plates a arranged above the four upper support plates; the four bearing discs are respectively arranged above the four connecting plates a, and the upper ends of the four bearing discs are fixedly connected with annular enclosures; and the lower end centers of the four bearing discs are fixedly connected to the upper end centers of the four connecting plates a through four support columns; the upper leveling mechanism includes an upper support frame, a connecting shaft, two upper cross beams, four connecting steel pipes, four Connecting lug d, four leveling hydraulic cylinders and four connecting lugs a; the four leveling hydraulic cylinders are respectively recorded as leveling hydraulic cylinder A, leveling hydraulic cylinder B, leveling hydraulic cylinder C and leveling hydraulic cylinder D; the upper support frame is composed of an upper frame, an intermediate connecting plate and four intermediate brackets of equal length, the upper frame is composed of two upper main beams b correspondingly distributed in the front and rear and two upper main beams a correspondingly distributed in the left and right, which are fixedly connected in sequence, and the size of the upper frame is smaller than that of the lower frame; the size of the intermediate connecting plate is smaller than that of the upper frame, and is arranged in the center below the upper frame; the upper ends of the four intermediate brackets are respectively fixedly connected to the ends of the two upper main beams b, and the lower ends thereof are respectively fixedly connected to the four corners of the upper end of the intermediate connecting plate; the left and A pair of connecting ear plates a are relatively fixedly connected to the right part, and a pair of through holes B are correspondingly opened in the lower part of the pair of connecting ear plates a; the connecting shaft is rotatably inserted into the pair of through holes B, and the left and right ends of the connecting shaft are correspondingly fixedly connected to two side end plates; the left side of the left side end plate and the right side front and rear ends of the right side end plate are respectively fixedly connected to two connecting ear plates b; the two upper cross beams are respectively arranged on the left and right sides above the lower support frame, and the ends of the two upper cross beams correspond to the tops of the four bearing discs respectively; the lower ends of the two upper cross beams are respectively fixedly connected to the four sliding shoes through four supporting bolts, and the four sliding shoes are respectively slidably arranged on the upper parts of the four bearing discs, and the sliding range is limited by the annular enclosures on the four bearing discs;The inner ends of the four connecting steel pipes are respectively fixedly connected to the outer ends of the four connecting plates e, and the inner ends of the four connecting plates e are respectively connected to the four connecting ear plates b through four connecting pins e; the outer ends of the four connecting steel pipes are respectively fixedly connected to the ends of the two upper cross beams; the upper ends of the four connecting lugs d are respectively fixedly connected to the four corners of the lower end of the upper frame; the lower ends of the four connecting lugs d are respectively rotatably connected to the upper ends of the four connecting lugs c through four connecting pins d; the piston rod ends of the four leveling hydraulic cylinders are respectively connected to the upper ends of the four connecting lugs c through four connecting pins c are rotatably connected to the lower ends of the four connecting lugs c respectively; the cylinder ends of the four leveling hydraulic cylinders are rotatably connected to the upper ends of the four connecting lugs b respectively through four connecting pins b; the lower ends of the four connecting lugs b are rotatably connected to the upper ends of the four connecting lugs a respectively through four connecting pins a, and the lower ends of the four connecting lugs a are fixedly connected to the upper parts of the outer ends of the four connecting steel pipes respectively; the top support beam a is fixedly connected between the two upper main beams a; the horizontal inclination sensor is installed in the middle of the top support beam a;

[0007] The hydraulic control system includes an electric motor, a variable displacement pump, a gear pump, a hydraulic suspension leveling control unit and a road simulation control unit;

[0008] The hydraulic suspension leveling control unit includes a leveling hydraulic cylinder A, a leveling hydraulic cylinder B, a leveling hydraulic cylinder C, a leveling hydraulic cylinder D, an electromagnetic proportional reversing valve A, an electromagnetic proportional reversing valve B, an electromagnetic proportional reversing valve C and an electromagnetic proportional reversing valve D; the road simulation control unit includes a supporting hydraulic cylinder A, a supporting hydraulic cylinder B, a supporting hydraulic cylinder C, a supporting hydraulic cylinder D, an electromagnetic proportional reversing valve E, an electromagnetic proportional reversing valve F, an electromagnetic proportional reversing valve G and an electromagnetic proportional reversing valve H;

[0009] The motor is connected to the variable pump and the gear pump through the transfer case, respectively. The suction ports of the variable pump and the gear pump are connected to the oil tank, and the discharge ports of the variable pump and the gear pump are connected to the oil tank through safety valve 1 and safety valve 2, respectively; the discharge port of the variable pump is also connected to the P ports of the electromagnetic proportional reversing valve A, the electromagnetic proportional reversing valve B, the electromagnetic proportional reversing valve C and the electromagnetic proportional reversing valve D through differential pressure reducing valve A, differential pressure reducing valve B, differential pressure reducing valve C and differential pressure reducing valve D, respectively; the T ports of the electromagnetic proportional reversing valve A, the electromagnetic proportional reversing valve B, the electromagnetic proportional reversing valve C and the electromagnetic proportional reversing valve D are all connected to the oil tank; the A port and the B port of the electromagnetic proportional reversing valve A are respectively connected to the rodless chamber and the rod chamber of the leveling hydraulic cylinder A, and are also respectively connected to the two comparison oil ports of the shuttle valve A, and the oil outlet of the shuttle valve A is connected to the control port of the differential pressure reducing valve A; the A port and the B port of the electromagnetic proportional reversing valve B are respectively connected to the rodless chamber and the rod chamber of the leveling hydraulic cylinder B The A and B ports of the electromagnetic proportional reversing valve C are respectively connected to the rodless chamber and the rod chamber of the leveling hydraulic cylinder C, and are also respectively connected to the two comparative oil ports of the shuttle valve C, and the oil outlet of the shuttle valve C is connected to the control port of the differential pressure reducing valve C; the A and B ports of the electromagnetic proportional reversing valve D are respectively connected to the rodless chamber and the rod chamber of the leveling hydraulic cylinder D, and are also respectively connected to the two comparative oil ports of the shuttle valve D, and the oil outlet of the shuttle valve D is connected to the control port of the differential pressure reducing valve D; the leveling hydraulic cylinder A, the leveling hydraulic cylinder B, the leveling hydraulic cylinder C, and the leveling hydraulic cylinder D are respectively connected with displacement sensors E, displacement sensors F, displacement sensors G, and displacement sensors H for measuring displacement, and are also respectively connected with acceleration sensors A, acceleration sensors B, acceleration sensors C, and acceleration sensors D for measuring acceleration;

[0010] The oil discharge port of the gear pump is also connected to the P ports of the electromagnetic proportional reversing valve E, the electromagnetic proportional reversing valve F, the electromagnetic proportional reversing valve G and the electromagnetic proportional reversing valve H, respectively. The T ports of the electromagnetic proportional reversing valve E, the electromagnetic proportional reversing valve F, the electromagnetic proportional reversing valve G and the electromagnetic proportional reversing valve H are all connected to the oil tank; the A port of the electromagnetic proportional reversing valve E is connected to the rodless cavity of the supporting hydraulic cylinder A through the hydraulically controlled check valve A and the variable throttle valve A in turn, and its B port is connected to the rod cavity of the supporting hydraulic cylinder A and the hydraulic control port of the hydraulically controlled check valve A, respectively; the A port of the electromagnetic proportional reversing valve F is connected to the rodless cavity of the supporting hydraulic cylinder B through the hydraulically controlled check valve B and the variable throttle valve B in turn, and its B port is connected to the rod cavity of the supporting hydraulic cylinder B, respectively. The rod cavity is connected to the hydraulic control port of the hydraulic control check valve B; the A port of the electromagnetic proportional reversing valve G is connected to the rodless cavity of the supporting hydraulic cylinder C through the hydraulic control check valve C and the variable throttle valve C in turn, and its B port is connected to the rod cavity of the supporting hydraulic cylinder C and the hydraulic control port of the hydraulic control check valve C; the A port of the electromagnetic proportional reversing valve H is connected to the rodless cavity of the supporting hydraulic cylinder D through the hydraulic control check valve D and the variable throttle valve D in turn, and its B port is connected to the rod cavity of the supporting hydraulic cylinder D and the hydraulic control port of the hydraulic control check valve D respectively; the supporting hydraulic cylinder A, the supporting hydraulic cylinder B, the supporting hydraulic cylinder C, and the supporting hydraulic cylinder D are respectively connected with displacement sensors A, displacement sensor B, displacement sensor C, and displacement sensor D for measuring displacement;

[0011] The controller is connected to the horizontal inclination sensor, displacement sensor A, displacement sensor B, displacement sensor C, displacement sensor D, displacement sensor E, displacement sensor F, displacement sensor G, displacement sensor H, acceleration sensor A, acceleration sensor B, acceleration sensor C and acceleration sensor D respectively.

[0012] Furthermore, in order to increase the contact area and reduce the pressure on the ground to prevent the test bench from damaging the ground, it also includes four supporting base plates, which are fixedly connected to the lower ends of the four supporting legs and are square.

[0013] Furthermore, in order to increase the connection strength, the end of the lower cross beam a and the upper end of the supporting leg, as well as the end of the lower cross beam b and the upper end of the supporting leg are fixedly connected by a triangular reinforcement plate; the middle part of the lower cross beam a and the lower part of the supporting leg, as well as the middle part of the lower cross beam b and the lower part of the supporting leg are fixedly connected by lower reinforcement ribs.

[0014] Furthermore, in order to increase the bearing capacity of the upper frame, two sides of the middle portion of the top support beam a are fixedly connected to the two upper main beams b through two top support beams b.

[0015] Furthermore, in order to facilitate installation and disassembly, four connecting plates d and four connecting plates c are also included. The four connecting plates d are respectively fixedly connected at the four corners of the lower end of the upper frame, and the four connecting plates c are respectively fixedly connected to the upper ends of the connecting lugs d. The four connecting plates d and the four connecting plates c are fixedly connected by multiple connecting bolts.

[0016] Furthermore, in order to facilitate installation and disassembly, a through hole C for the support bolt to pass through is provided at the end of the upper cross beam, the upper end of the support bolt passes through the through hole C, and the nut b and the nut a are respectively connected by threaded fitting on the upper and lower sides of the upper cross beam.

[0017] Furthermore, in order to prevent impurities from clogging the valve body inside the system, the oil suction port of the variable pump is connected to the oil tank through filter A, and the oil suction port of the gear pump is connected to the oil tank through filter B; in order to cool the hydraulic oil, the T ports of the electromagnetic proportional reversing valve E, the electromagnetic proportional reversing valve F, the electromagnetic proportional reversing valve G and the electromagnetic proportional reversing valve H are all connected to the oil tank through a cooler.

[0018] Furthermore, in order to simulate the actual load condition, a counterweight block is also included which is fixedly connected to the center of the upper end of the support frame.

[0019] In the present invention, the lower support frame can effectively support the entire test bench, and the piston rods of the four supporting hydraulic cylinders connected to the lower parts of the four upper supporting plates can pass through the through hole A in the upper supporting plate to control the bearing disc supporting the upper support to be lifted and lowered in the longitudinal direction, so that the outer end of the corresponding connecting steel pipe can be lifted and lowered in the longitudinal direction, and the undulating state of the road surface can be effectively simulated through the stroke control of the four supporting hydraulic cylinders. The hydraulically controlled one-way valve can realize various positions of the locking hydraulic cylinder, and the variable throttle valve can control the oil supply flow, so that the dual functions of flow regulation and hydraulic cylinder locking can be taken into account, and the undulating state of the road surface can be better simulated. The supporting hydraulic cylinder is controlled by an electromagnetic proportional reversing valve, which can facilitate the road surface simulation process through switch quantity control, thereby saving costs. The end of the connecting steel pipe is fixedly connected to the sliding shoe slidably set on the bearing disc through a supporting bolt, so that the sliding shoe can have a certain sliding space during the rotation of the connecting steel pipe around the connecting pin a, so as to more effectively simulate the uphill or downhill process. The upper support frame can have a certain degree of rotational freedom around the connecting axis through the through hole B on the connecting ear plate a, and the connecting steel pipe can have a certain degree of rotational freedom around the connecting pin e relative to the upper support frame, while the upper end of the leveling hydraulic cylinder has a certain degree of rotational freedom relative to the upper end of the upper support frame, and the lower end of the leveling hydraulic cylinder has a certain degree of rotational freedom relative to the outer end of the connecting steel pipe, thereby effectively simulating the hydraulic suspension. The electromagnetic proportional reversing valve connected to the leveling hydraulic cylinder is pressure compensated by the differential pressure reducing valve, thereby ensuring that the oil supply flow of the leveling hydraulic cylinder is only related to the opening size of the electromagnetic proportional reversing valve and has nothing to do with the workload, reducing the system impact, effectively improving the control accuracy, and realizing the leveling operation more accurately. When the two supporting hydraulic cylinders in the front of the lower support frame are extended to simulate the uphill, the piston rods of the two leveling hydraulic cylinders on the rear side of the upper support frame can be controlled to extend for compensation, so that the upper support frame remains horizontal. When the two supporting hydraulic cylinders in the rear of the lower support frame are extended to simulate the downhill, the piston rods of the two leveling hydraulic cylinders on the front side of the upper support frame can be controlled to extend for compensation, so that the upper support frame continues to remain horizontal. This test bench has multiple degrees of freedom, which can effectively simulate the actual road spectrum. At the same time, it can effectively compensate for the uphill state and the downhill state, so that the upper support frame always remains horizontal. The extension or retraction speed of the hydraulic cylinder piston rod can also be changed by controlling the oil flow of the hydraulic cylinder to indirectly simulate the different walking speeds of the vehicle. Compared with the traditional test bench, this test bench simplifies the system structure, makes the hydraulic system easier to implement, effectively reduces the manufacturing cost of the test bench, and the hydraulic system is easier to implement, can effectively simulate a variety of road unevenness, and at the same time, can feedback the horizontality through the horizontal inclination sensor, and then verify the effect of the leveling hydraulic suspension in real time.The system uses a variable pump as a power element. When the system is not working, the output flow of the variable pump only maintains the system leakage. When the leveling operation starts, the output flow of the variable pump increases rapidly, ensuring the rapid response of the system. The cooler can cool the hydraulic cylinder, effectively improving the economy of the system and reducing the heating of the system. The road surface roughness can be easily obtained through the horizontal inclination sensor. The present invention can easily obtain multiple parameters such as road surface roughness, hydraulic suspension response speed, frame adjustment level, etc., and can better complete the test process of the automatic leveling hydraulic suspension. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention;

[0021] Figure 2 yes Figure 1 Right view of;

[0022] Figure 3 yes Figure 1 A top view of

[0023] Figure 4 It is the hydraulic principle diagram of the present invention.

[0024] In the figure: 1, supporting bottom plate, 2, supporting leg, 3, triangular reinforcement plate, 4, supporting hydraulic cylinder, 5, lower cross beam a, 6, lower reinforcement rib, 7, lower cross beam b, 8, connecting plate a, 9, supporting column, 10, load-bearing disc, 11, supporting bolt, 12, upper cross beam, 13, connecting pin a, 14, connecting pin b, 15, leveling hydraulic cylinder, 16, connecting lug a, 17, connecting lug b, 18, middle connecting plate, 19, middle bracket, 20, connecting pin c, 21, connecting lug c, 22, connecting lug d, 23, connecting plate c, 24, connecting plate d, 25, connecting bolt, 26, upper main beam a, 27, upper main beam b, 28. Connecting steel pipe, 29. Connecting plate e, 30. Connecting pin e, 31. Connecting shaft, 32. Top support beam a, 33. Top support beam b, 34. Upper support plate, 35. Annular enclosure, 36. Slipper, 37. Nut a, 38. Nut b, 39. Connecting pin d, 40. Horizontal inclination sensor, 41. Connecting ear plate a, 42. Side end plate, 43. Connecting ear plate b, 44. Lower frame, 45. Upper frame, 46. Motor, 47. Variable pump, 48. Gear pump, 49. Safety valve 1, 50. Safety valve 2, 51. Oil tank, 52. Differential pressure reducing valve A, 53. Differential pressure reducing valve B, 54. Differential pressure reducing valve C, 5 5. Differential pressure reducing valve D, 56. Solenoid proportional reversing valve A, 57. Solenoid proportional reversing valve B, 58. Solenoid proportional reversing valve C, 59. Solenoid proportional reversing valve D, 60. Leveling hydraulic cylinder A, 61. Leveling hydraulic cylinder B, 62. Leveling hydraulic cylinder C, 63. Leveling hydraulic cylinder D, 64. Support hydraulic cylinder A, 65. Support hydraulic cylinder B, 66. Support hydraulic cylinder C, 67. Support hydraulic cylinder D, 68. Solenoid proportional reversing valve E, 69. Solenoid proportional reversing valve F, 70. Solenoid proportional reversing valve G, 71. Solenoid proportional reversing valve H, 72. Shuttle valve A, 73. Shuttle valve B, 74. Shuttle valve C, 75. Shuttle valve D, 76. Hydraulic control check valve A, 77. Variable throttle valve A, 78. Hydraulic control one-way valve B, 79. Variable throttle valve B, 80. Hydraulic control one-way valve C, 81. Variable throttle valve C, 82. Hydraulic control one-way valve D, 83. Variable throttle valve D, 84. Displacement sensor A, 85. Displacement sensor B, 86. Displacement sensor C, 87. Displacement sensor D, 88. Displacement sensor E, 89. Displacement sensor F, 90. Displacement sensor G, 91. Displacement sensor H, 92. Acceleration sensor A, 93. Acceleration sensor B, 94. Acceleration sensor C, 95. Acceleration sensor D, 96. Counterweight, 97. Filter A, 98. Filter B, 99. Cooler. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings.

[0026] like Figures 1 to 4As shown, a hydraulic system for an automatic leveling test bench includes an automatic leveling test bench, a hydraulic control system and a controller;

[0027] The automatic leveling test bench includes a lower support frame, four upper support plates 34, four supporting hydraulic cylinders 4, four bearing discs 10, an upper leveling mechanism, a top support beam a32 and a horizontal inclination sensor 40; the lower support frame is composed of a lower frame 44 and four support legs 2 of equal length, and the lower frame 44 is composed of two lower cross beams a5 correspondingly distributed in the front and back and two lower cross beams b7 correspondingly distributed in the left and right, which are fixedly connected in sequence, and the upper ends of the four support legs 2 are respectively fixedly connected to the four corners of the lower end of the lower frame 44; the support legs 2 can be made of square tubes, and the size of the square tubes can be designed according to actual conditions, for example, the cross-sectional size can be 80mmx80mm, and the thickness can be 5mm. The four upper support plates 34 are respectively fixedly connected at the four corners of the upper end of the lower frame 44, and a through hole A is opened in the center of the four upper support plates 34; the four supporting hydraulic cylinders 4 are respectively recorded as supporting hydraulic cylinder A64, supporting hydraulic cylinder B65, supporting hydraulic cylinder C66 and supporting hydraulic cylinder D67; as a preferred embodiment, the thickness of the upper support plate 34 is 10mm. The four supporting hydraulic cylinders 4 are respectively arranged at the lower part of the four upper support plates 34, and the lower ends of the cylinder barrels of the supporting hydraulic cylinders 4 are all located above the lower end of the supporting leg 2; the upper ends of the cylinder barrels of the four supporting hydraulic cylinders 4 are respectively fixedly connected to the lower end surfaces of the four upper support plates 34, and the piston rods of the four supporting hydraulic cylinders 4 slide through the through holes A on the four upper support plates 34, and are respectively fixedly connected to the four connecting plates a8 arranged above the four upper support plates 34; as a preferred embodiment, the thickness of the connecting plate a8 is 10mm;

[0028] As a preferred embodiment, the supporting hydraulic cylinder 4 is a double-acting hydraulic cylinder with a maximum stroke of 200 mm.

[0029] The lower cross beam a5 and the lower cross beam b7 can both be made of square tubes. The size of the square tubes can be designed according to actual conditions. For example, the cross-sectional size can be 60mmx60mm and the thickness can be 5mm.

[0030] Four bearing discs 10 are respectively arranged above four connecting plates a8, and the upper ends of the four bearing discs 10 are fixedly connected with an annular enclosure 35; and the lower end centers of the four bearing discs 10 are fixedly connected to the upper end centers of the four connecting plates a8 through four support columns 9; as a preferred embodiment, the support column 9 is a cylinder with a diameter of 20 mm, and its height can be 30 mm. As a preferred embodiment, the diameter of the bearing disc 10 is 20 mm and the thickness is 10 mm. The height of the annular enclosure 35 is preferably 20 mm, and the thickness is preferably 3 mm.

[0031] The upper leveling mechanism includes an upper support frame, a connecting shaft 31, two upper cross beams 12, four connecting steel pipes 28, four connecting lugs d22, four leveling hydraulic cylinders 15 and four connecting lugs a16; the four leveling hydraulic cylinders 15 are respectively recorded as leveling hydraulic cylinder A60, leveling hydraulic cylinder B61, leveling hydraulic cylinder C62 and leveling hydraulic cylinder D63; the upper support frame is composed of an upper frame 45, an intermediate connecting plate 18 and four intermediate brackets 19 of equal length, and the upper frame 45 is composed of two upper main beams b27 correspondingly distributed in the front and back and two upper main beams a26 correspondingly distributed in the left and right, which are fixedly connected in sequence. As a preferred embodiment, the upper main beams a26 and the upper main beams b27 can be made of square tubes, and the size of the square tubes can be designed according to actual conditions, for example, the cross-sectional size can be 40mmx40mm. As a preferred embodiment, the intermediate connecting plate 18 can be made of a steel plate with a size of 150mmx150mm. The intermediate bracket 19 can be made of a square tube, and the size of the square tube can be designed according to actual conditions. For example, the cross-sectional size can be 40 mm x 40 mm.

[0032] The size of the upper frame 45 is smaller than that of the lower frame 44; the size of the intermediate connecting plate 18 is smaller than that of the upper frame 45, and is arranged at the center below the upper frame 45; the upper ends of the four intermediate brackets 19 are respectively fixedly connected to the ends of the two upper main beams b27, and the lower ends thereof are respectively fixedly connected to the four corners of the upper end of the intermediate connecting plate 18; the left and right parts of the lower end of the intermediate connecting plate 18 are relatively fixedly connected with a pair of connecting ear plates a41, and the lower parts of the pair of connecting ear plates a41 are correspondingly provided with a pair of through holes B; the connecting shaft 31 is rotatably inserted into the pair of through holes B, and the left and right ends of the connecting shaft 31 are correspondingly fixedly connected to two side end plates 42; the left side The left and right ends of the end plate 42 and the right front and rear ends of the side end plate 42 are respectively fixedly connected with two connecting ear plates b43; the two upper cross beams 12 are respectively arranged on the left and right sides above the lower support frame, and the ends of the two upper cross beams 12 correspond to the tops of the four bearing discs 10; the lower ends of the two upper cross beams 12 are respectively fixedly connected with the four sliding shoes 36 through four supporting bolts 11, and the four sliding shoes 36 are respectively slidably arranged on the upper parts of the four bearing discs 10, and the sliding range is limited by the annular enclosure 35 on the four bearing discs 10; as a preferred embodiment, the bottom of the sliding shoe 36 is coated with lubricating oil to reduce the resistance during the sliding process. As a preferred embodiment, the specification of the supporting bolt 11 is M20x150mm. The upper cross beam 12 can be made of square tubes, and the size of the square tube can be designed according to actual conditions, for example, its cross-sectional size can be 40mmx40mm and the thickness is 5mm.

[0033] As a preference, the vertical distance between the two upper cross beams 12 is equal to the actual wheelbase of the simulated vehicle; the length of the upper cross beam 12 is equal to the actual wheelbase of the simulated vehicle, so as to effectively improve the simulation effect.

[0034] The inner ends of the four connecting steel pipes 28 are fixedly connected to the outer ends of the four connecting plates e29 respectively, and the inner ends of the four connecting plates e29 are connected to the four connecting ear plates b43 respectively through four connecting pins e30; the outer ends of the four connecting steel pipes 28 are fixedly connected to the ends of the two upper cross beams 12 respectively; as a preferred embodiment, the connecting steel pipes 28 can be made of square pipes, and the size of the square pipes can be designed according to actual conditions, for example, its cross-sectional size can be 50mmx50mm. The connecting plate e29 can be made of a steel plate with a thickness of 4mm.

[0035] The upper ends of the four connecting lugs d22 are fixedly connected to the four corners of the lower end of the upper frame 45; the lower ends of the four connecting lugs d22 are rotatably connected to the upper ends of the four connecting lugs c21 through four connecting pins d39; the piston rod ends of the four leveling hydraulic cylinders 15 are rotatably connected to the lower ends of the four connecting lugs c21 through four connecting pins c20; as a preferred embodiment, the leveling hydraulic cylinder 15 is a double-acting hydraulic cylinder. Its parameters such as stroke, cylinder diameter, rod diameter ratio, etc. can be selected according to actual needs.

[0036] The four leveling hydraulic cylinders 15 correspond to the four wheel suspensions respectively, and can adjust the frame within a certain range to make it reach a horizontal state.

[0037] The cylinder ends of the four leveling hydraulic cylinders 15 are rotatably connected to the upper ends of the four connecting lugs b17 through four connecting pins b14; the lower ends of the four connecting lugs b17 are rotatably connected to the upper ends of the four connecting lugs a16 through four connecting pins a13, and the lower ends of the four connecting lugs a16 are fixedly connected to the upper parts of the outer ends of the four connecting steel pipes 28; the top support beam a32 is fixedly connected between the two upper main beams a26; the horizontal inclination sensor 40 is installed in the middle of the top support beam a32;

[0038] The hydraulic control system includes an electric motor 46, a variable displacement pump 47, a gear pump 48, a hydraulic suspension leveling control unit and a road simulation control unit;

[0039] The hydraulic suspension leveling control unit includes a leveling hydraulic cylinder A60, a leveling hydraulic cylinder B61, a leveling hydraulic cylinder C62, a leveling hydraulic cylinder D63, an electromagnetic proportional reversing valve A56, an electromagnetic proportional reversing valve B57, an electromagnetic proportional reversing valve C58 and an electromagnetic proportional reversing valve D59; the road simulation control unit includes a supporting hydraulic cylinder A64, a supporting hydraulic cylinder B65, a supporting hydraulic cylinder C66, a supporting hydraulic cylinder D67, an electromagnetic proportional reversing valve E68, an electromagnetic proportional reversing valve F69, an electromagnetic proportional reversing valve G70 and an electromagnetic proportional reversing valve H71;

[0040] Solenoid proportional reversing valve A56, solenoid proportional reversing valve B57, solenoid proportional reversing valve C58 and solenoid proportional reversing valve D59 all have an O-type neutral position function, which can control the flow direction of the system hydraulic oil by changing the three valve core positions of left, middle and right. When the left position of the above three-position four-way solenoid proportional reversing valve is energized, the oil circuit between its P port and its A port is connected, and the oil circuit between its T port and its B port is connected. When the right position is energized, the oil circuit between its P port and its B port is connected, and the oil circuit between its T port and its A port is connected. When the left and right positions are not energized, it works in the neutral position, and its P port, T port, A port and B port are all cut off;

[0041] The electromagnetic proportional reversing valve E68, electromagnetic proportional reversing valve F69, electromagnetic proportional reversing valve G70 and electromagnetic proportional reversing valve H71 are all three-position four-way electromagnetic proportional reversing valves, all of which have a Y-type neutral position function, and can control the flow direction of the system hydraulic oil by changing the three valve core positions of left, middle and right. When the left position of the above three-position four-way electromagnetic proportional reversing valve is energized, the oil circuit between its P port and its A port is connected, and the oil circuit between its T port and its B port is connected. When the right position is energized, the oil circuit between its P port and its B port is connected, and the oil circuit between its T port and its A port is connected. When both the left and right positions are not energized, it works in the neutral position, its P port is cut off, and its T port is connected to its A port and B port at the same time;

[0042] As a preferred embodiment, the rated speed of the motor 46 is 1500r / min, and the motor 46 is connected to the variable pump 47 and the gear pump 48 through the transfer case, wherein one shaft of the transfer case is connected to the power element gear pump 3 through a transmission gear, and the other shaft is connected to the variable pump 2 through a coupling. As a preferred embodiment, the variable pump 2 is a constant pressure variable pump. The constant pressure variable pump is the power element of the system, which can adjust its own displacement to maintain the system pressure stability and has a faster response speed.

[0043] The transmission gear has a speed increasing function, and the transmission ratio is 2. As a preferred embodiment, the gear pump is an external gear pump 3, and its displacement can be selected according to the size and stroke of the actuator.

[0044] The oil suction ports of the variable pump 47 and the gear pump 48 are connected to the oil tank 51, and the oil discharge ports of the variable pump 47 and the gear pump 48 are connected to the oil tank 51 through the safety valve 1 49 and the safety valve 2 50 respectively; the safety valve is used to ensure the safety of the system when the actuator is not working or the system pressure is too high. As a preferred embodiment, the set pressure of the safety valve is 120%. The oil discharge port of the variable pump 47 is also connected to the P port of the electromagnetic proportional reversing valve A56, the electromagnetic proportional reversing valve B57, the electromagnetic proportional reversing valve C58 and the electromagnetic proportional reversing valve D59 through the differential pressure reducing valve A52, the differential pressure reducing valve B53, the differential pressure reducing valve C54 and the differential pressure reducing valve D55 respectively; the T port of the electromagnetic proportional reversing valve A56, the electromagnetic proportional reversing valve B57, the electromagnetic proportional reversing valve C58 and the electromagnetic proportional reversing valve D59 are all connected to the oil tank 51; the A port and the B port of the electromagnetic proportional reversing valve A56 are respectively connected to the rodless chamber of the leveling hydraulic cylinder A60 , and the rod chamber, and are also connected to the two comparative oil ports of shuttle valve A72, and the oil outlet of shuttle valve A72 is connected to the control port of differential pressure reducing valve A52; the A port and B port of electromagnetic proportional reversing valve B57 are respectively connected to the rodless chamber and the rod chamber of leveling hydraulic cylinder B61, and are also connected to the two comparative oil ports of shuttle valve B73, and the oil outlet of shuttle valve B73 is connected to the control port of differential pressure reducing valve B53; the A port and B port of electromagnetic proportional reversing valve C58 are respectively connected to the rodless chamber and the rod chamber of leveling hydraulic cylinder C62, and are also connected to the two comparative oil ports of shuttle valve C74, and are also connected to the control port of differential pressure reducing valve B53. The oil outlet of shuttle valve C74 is connected to the control port of differential pressure reducing valve C54; the A port and B port of electromagnetic proportional reversing valve D59 are respectively connected to the rodless chamber and rod chamber of leveling hydraulic cylinder D63, and are also respectively connected to the two comparison oil ports of shuttle valve D75, and the oil outlet of shuttle valve D75 is connected to the control port of differential pressure reducing valve D55; displacement sensors E88, F89, and G90 for measuring displacement are respectively connected to leveling hydraulic cylinder A60, leveling hydraulic cylinder B61, leveling hydraulic cylinder C62, and leveling hydraulic cylinder D63 and displacement sensor H91, and acceleration sensor A92, acceleration sensor B93, acceleration sensor C94 and acceleration sensor D95 for measuring acceleration are also connected respectively; the displacement sensor and acceleration sensor are connected to the piston rod of the leveling hydraulic cylinder, and are used to measure the displacement and acceleration of the piston rod respectively; the horizontal inclination sensor is installed on the upper frame, and is used to measure the horizontal degree of the upper frame. All the data collected by the test elements are transmitted to the controller, and the controller can also be connected to the host computer for data processing through the host computer. As a preferred embodiment, the model of the controller is TTC60.

[0045] The differential pressure reducing valve and shuttle valve are used in pairs to form a pressure compensation system to ensure that the pressure difference on both sides of the electromagnetic proportional reversing valve remains unchanged.

[0046] The oil discharge port of the gear pump 48 is also connected to the P ports of the electromagnetic proportional reversing valve E68, the electromagnetic proportional reversing valve F69, the electromagnetic proportional reversing valve G70 and the electromagnetic proportional reversing valve H71 respectively, and the T ports of the electromagnetic proportional reversing valve E68, the electromagnetic proportional reversing valve F69, the electromagnetic proportional reversing valve G70 and the electromagnetic proportional reversing valve H71 are all connected to the oil tank; the A port of the electromagnetic proportional reversing valve E68 is connected to the oil tank through the hydraulically controlled one-way valve A76 and the variable throttle valve in turn. A77 is connected to the rodless cavity of the supporting hydraulic cylinder A64, and its B port is connected to the rod cavity of the supporting hydraulic cylinder A64 and the hydraulic control port of the hydraulic control check valve A76 respectively; the A port of the electromagnetic proportional reversing valve F69 is connected to the rodless cavity of the supporting hydraulic cylinder B65 through the hydraulic control check valve B78 and the variable throttle valve B79 in turn, and its B port is connected to the rod cavity of the supporting hydraulic cylinder B65 and the hydraulic control port of the hydraulic control check valve B78 respectively; the electromagnetic proportional reversing valve G7 The A port of 0 is connected to the rodless cavity of the supporting hydraulic cylinder C66 through the hydraulically controlled one-way valve C80 and the variable throttle valve C81 in sequence, and its B port is connected to the rod cavity of the supporting hydraulic cylinder C66 and the hydraulically controlled port of the hydraulically controlled one-way valve C80; the A port of the electromagnetic proportional reversing valve H71 is connected to the rodless cavity of the supporting hydraulic cylinder D67 through the hydraulically controlled one-way valve D82 and the variable throttle valve D83 in sequence, and its B port is connected to the rod cavity of the supporting hydraulic cylinder D67 and the hydraulically controlled port of the hydraulically controlled one-way valve D82; the supporting hydraulic cylinder A64, the supporting hydraulic cylinder B65, the supporting hydraulic cylinder C66, and the supporting hydraulic cylinder D67 are respectively connected with displacement sensors A84, B85, C86, and D87 for measuring displacement; as a preferred embodiment, the above-mentioned displacement sensors are wire-pull type displacement sensors, which are used to monitor the displacement size of the supporting hydraulic cylinder in real time and transmit the data to the controller.

[0047] The main function of the hydraulic control check valve is to lock the position of the hydraulic cylinder. The variable throttle valve can change the diameter of its own throttle port to control the system flow.

[0048] The controller is respectively connected to the horizontal inclination sensor 40, displacement sensor A84, displacement sensor B85, displacement sensor C86, displacement sensor D87, displacement sensor E88, displacement sensor F89, displacement sensor G90, displacement sensor H91, acceleration sensor A92, acceleration sensor B93, acceleration sensor C94 and acceleration sensor D95.

[0049] In order to increase the contact area and reduce the pressure on the ground to prevent the test bench from damaging the ground, four support base plates 1 are also included. The four support base plates 1 are fixedly connected to the lower ends of the four support legs 2. The support base plates 1 are square. The size of the support base plates 1 can be designed according to actual conditions, for example, the area can be 100mmx100mm and the thickness can be 5mm.

[0050] In order to increase the connection strength and prevent impact damage, the end of the lower cross beam a5 and the upper end of the support leg 2, and the end of the lower cross beam b7 and the upper end of the support leg 2 are fixedly connected by a triangular reinforcing plate 3; the middle of the lower cross beam a5 and the lower part of the support leg 2, and the middle of the lower cross beam b7 and the lower part of the support leg 2 are fixedly connected by a lower reinforcing rib 6. Preferably, the triangular reinforcing plate 3 is an isosceles right triangle, and its size is preferably 100mmx100mm and the thickness is 5mm. Preferably, the lower reinforcing rib 6 is made of a square tube, and the size of the square tube can be designed according to actual conditions, for example, its cross-sectional size can be 40mmx40mm.

[0051] Because in the actual working process, the upper frame 45 also needs to be set with a load of a certain mass. In order to increase the bearing capacity of the upper frame 45, the two sides of the middle of the top support beam a32 are fixedly connected to the two upper main beams b27 through two top support beams b33.

[0052] In order to facilitate installation and disassembly, four connecting plates d24 and four connecting plates c23 are also included. The four connecting plates d24 are respectively fixedly connected to the four corners of the lower end of the upper frame 45, and the four connecting plates c23 are respectively fixedly connected to the upper ends of the connecting lugs d22. The four connecting plates d24 and the four connecting plates c23 are fixedly connected by multiple connecting bolts 25.

[0053] To facilitate installation and disassembly, a through hole C for the support bolt 11 to pass through is provided at the end of the upper cross beam 12. The upper end of the support bolt 11 passes through the through hole C, and nuts b38 and nuts a37 are respectively connected by threaded fittings on the upper and lower sides of the upper cross beam 12.

[0054] In order to prevent impurities from blocking the valve body inside the system, the oil suction port of the variable pump 47 is connected to the oil tank 51 through the filter A97, and the oil suction port of the gear pump 48 is connected to the oil tank 51 through the filter B98; in order to cool the hydraulic oil, the T ports of the electromagnetic proportional reversing valve E68, the electromagnetic proportional reversing valve F69, the electromagnetic proportional reversing valve G70 and the electromagnetic proportional reversing valve H71 are all connected to the oil tank 51 through the cooler 99. The filter is used to filter impurities in the oil tank 51, and the filter filtration accuracy is 100um.

[0055] In order to simulate the actual load condition, a counterweight block 96 is also included which is fixedly connected to the center of the upper end of the support frame 45 .

[0056] In the actual working process, the controller controls the electromagnetic proportional reversing valve E68, the electromagnetic proportional reversing valve F69, the electromagnetic proportional reversing valve G70 and the electromagnetic proportional reversing valve H71 to control the extension and retraction of the piston rods of the support hydraulic cylinder A64, the support hydraulic cylinder B65, the support hydraulic cylinder C66 and the support hydraulic cylinder D67 respectively to simulate the ground road spectrum. The controller can adjust the extension and retraction speed of the support hydraulic cylinder by controlling the change in the oil supply amount of the electromagnetic proportional reversing valve. When simulating the uphill process, the electromagnetic proportional reversing valves corresponding to the two front support hydraulic cylinders can be controlled to extend the piston rods of the two front support hydraulic cylinders, and the two rear support hydraulic cylinders remain in the maximum contraction state and do not move, and combined with the actual vehicle's wheelbase and track to simulate a certain degree of slope. During the simulation of uphill climbing, if you want to simulate different slopes, you can make the piston rods of the two front supporting hydraulic cylinders extend to different lengths, or you can make the extension speeds different according to the required situation. Similarly, during the simulation of downhill climbing, control the two front supporting hydraulic cylinders to maintain the maximum retraction state unchanged, and extend the piston rods of the two rear supporting hydraulic cylinders. During the simulation of downhill climbing, if you want to simulate different slopes, you can make the piston rods of the two rear supporting hydraulic cylinders extend to different lengths, or you can make the extension speeds different according to the required situation. The upper support frame is mainly used to simulate the actual hydraulic suspension. When the lower support hydraulic cylinder simulates the road spectrum, the controller controls the action of the electromagnetic proportional reversing valve A56, the electromagnetic proportional reversing valve B57, the electromagnetic proportional reversing valve C58 and the electromagnetic proportional reversing valve D59 through the signal fed back by the horizontal inclination sensor, and then controls the action of the piston rods of the leveling hydraulic cylinder A60, the leveling hydraulic cylinder B61, the leveling hydraulic cylinder C62 and the leveling hydraulic cylinder D63, so that the horizontal tilt sensor 40 remains in a horizontal state, so that the frame can always remain in a horizontal state.

Claims

1. A hydraulic system for an automatic leveling test bench, comprising an automatic leveling test bench, characterized in that: Also included are hydraulic control systems and controllers; The automatic leveling test bench comprises a lower support frame, four upper support plates (34), four support hydraulic cylinders (4), four bearing discs (10), an upper leveling mechanism, a top support beam a (32) and a horizontal tilt sensor (40); the lower support frame is composed of a lower frame (44) and four support legs (2) of equal length; the lower frame (44) is composed of two lower cross beams a (5) correspondingly distributed front and rear and two lower cross beams b (7) correspondingly distributed left and right, which are fixedly connected in sequence; the upper ends of the four support legs (2) are respectively fixedly connected to the four corners of the lower end of the lower frame (44); the four upper support plates (34) are respectively fixedly connected to the four corners of the upper ... legs (34) are respectively fixedly connected to the four corners of the upper end of the lower frame (44); the four upper support legs (34) are respectively fixedly connected to the four corners of the upper end of the lower frame (44); the four upper support legs (34) are respectively fixedly connected to the four corners of the upper end of the lower frame (44); the four upper support legs (34) are respectively fixedly connected to the four corners of the upper end of the lower frame (44); the four The center of each plate (34) is provided with a through hole A; the four supporting hydraulic cylinders (4) are respectively recorded as supporting hydraulic cylinder A (64), supporting hydraulic cylinder B (65), supporting hydraulic cylinder C (66) and supporting hydraulic cylinder D (67); the four supporting hydraulic cylinders (4) are respectively arranged at the lower part of the four upper supporting plates (34), and the lower ends of the cylinder barrels of the supporting hydraulic cylinders (4) are all located above the lower end of the supporting leg (2); the upper ends of the cylinder barrels of the four supporting hydraulic cylinders (4) are respectively fixedly connected to the lower end surfaces of the four upper supporting plates (34), and the piston rods of the four supporting hydraulic cylinders (4) are respectively slid through the through holes A on the four upper supporting plates (34) and are respectively connected to the four connecting plates a (8) arranged above the four upper supporting plates (34). ) are fixedly connected; four bearing discs (10) are respectively arranged above four connecting plates a (8); the upper ends of the four bearing discs (10) are fixedly connected with an annular enclosure plate (35); and the lower end centers of the four bearing discs (10) are fixedly connected with the upper end centers of the four connecting plates a (8) through four supporting columns (9); the upper leveling mechanism comprises an upper support frame, a connecting shaft (31), two upper cross beams (12), four connecting steel pipes (28), four connecting lugs d (22), four leveling hydraulic cylinders (15) and four connecting lugs a (16); the four leveling hydraulic cylinders (15) are respectively denoted as leveling hydraulic cylinder A (60), leveling hydraulic cylinder B (61), leveling hydraulic cylinder C (62) and A leveling hydraulic cylinder D (63); the upper support frame is composed of an upper frame (45), an intermediate connecting plate (18) and four intermediate brackets (19) of equal length; the upper frame (45) is composed of two upper main beams b (27) correspondingly distributed in the front and rear and two upper main beams a (26) correspondingly distributed in the left and right, which are fixedly connected in sequence; the size of the upper frame (45) is smaller than that of the lower frame (44); the size of the intermediate connecting plate (18) is smaller than that of the upper frame (45) and is arranged at the center below the upper frame (45); the upper ends of the four intermediate brackets (19) are respectively fixedly connected to the ends of the two upper main beams b (27), and the lower ends thereof are respectively fixedly connected to the four corners of the upper end of the intermediate connecting plate (18);A pair of connecting ear plates a (41) are fixedly connected to the left and right parts of the lower end of the middle connecting plate (18), and a pair of through holes B are correspondingly opened in the lower parts of the pair of connecting ear plates a (41); the connecting shaft (31) is rotatably inserted into the pair of through holes B, and the left and right ends of the connecting shaft (31) are fixedly connected to two side end plates (42) respectively; the left side of the left side end plate (42) and the right side of the right side end plate (42) are respectively fixedly connected to two connecting ear plates b (43); the two upper cross beams (12) are respectively arranged on the left and right sides above the lower support frame, and The ends of the two upper cross beams (12) correspond to the tops of the four bearing discs (10); the lower ends of the two upper cross beams (12) are fixedly connected to the four sliding shoes (36) through four supporting bolts (11); the four sliding shoes (36) are slidably arranged on the tops of the four bearing discs (10), and the sliding range is limited by the annular enclosure plates (35) on the four bearing discs (10); the inner ends of the four connecting steel pipes (28) are fixedly connected to the outer ends of the four connecting plates e (29), and the inner ends of the four connecting plates e (29) are connected by four connecting pins e ( 30) are respectively connected to four connecting ear plates b (43); the outer ends of the four connecting steel pipes (28) are respectively fixedly connected to the ends of the two upper cross beams (12); the upper ends of the four connecting lugs d (22) are respectively fixedly connected to the four corners of the lower end of the upper frame (45); the lower ends of the four connecting lugs d (22) are respectively rotatably connected to the upper ends of the four connecting lugs c (21) through four connecting pins d (39); the piston rod ends of the four leveling hydraulic cylinders (15) are respectively rotatably connected to the lower ends of the four connecting lugs c (21) through four connecting pins c (20); the four leveling hydraulic cylinders (15) are respectively connected to the lower ends of the four connecting lugs c (21) through four connecting pins c (20); The cylinder end of the flat hydraulic cylinder (15) is rotatably connected to the upper ends of four connecting lugs b (17) through four connecting pins b (14); the lower ends of the four connecting lugs b (17) are rotatably connected to the upper ends of four connecting lugs a (16) through four connecting pins a (13); the lower ends of the four connecting lugs a (16) are fixedly connected to the upper parts of the outer ends of four connecting steel pipes (28); the top support beam a (32) is fixedly connected between the two upper main beams a (26); the horizontal inclination sensor (40) is installed in the middle of the top support beam a (32); The hydraulic control system comprises an electric motor (46), a variable displacement pump (47), a gear pump (48), a hydraulic suspension leveling control unit and a road surface simulation control unit; The hydraulic suspension leveling control unit comprises a leveling hydraulic cylinder A (60), a leveling hydraulic cylinder B (61), a leveling hydraulic cylinder C (62), a leveling hydraulic cylinder D (63), an electromagnetic proportional reversing valve A (56), an electromagnetic proportional reversing valve B (57), an electromagnetic proportional reversing valve C (58) and an electromagnetic proportional reversing valve D (59); the road surface simulation control unit comprises a supporting hydraulic cylinder A (64), a supporting hydraulic cylinder B (65), a supporting hydraulic cylinder C (66), a supporting hydraulic cylinder D (67), an electromagnetic proportional reversing valve E (68), an electromagnetic proportional reversing valve F (69), an electromagnetic proportional reversing valve G (70) and an electromagnetic proportional reversing valve H (71); The motor (46) is connected to the variable pump (47) and the gear pump (48) through a transfer case, respectively; the oil suction ports of the variable pump (47) and the gear pump (48) are both connected to an oil tank (51); the oil discharge ports of the variable pump (47) and the gear pump (48) are connected to the oil tank (51) through a safety valve 1 (49) and a safety valve 2 (50), respectively; the oil discharge port of the variable pump (47) is also connected to an electromagnetic proportional reversing valve A (56), an electromagnetic proportional reversing valve B (57), an electromagnetic proportional reversing valve C (54), and a differential pressure reducing valve D (55), respectively. The electromagnetic proportional reversing valve C (58) and the electromagnetic proportional reversing valve D (59) are connected to the P port; the electromagnetic proportional reversing valve A (56), the electromagnetic proportional reversing valve B (57), the electromagnetic proportional reversing valve C (58) and the electromagnetic proportional reversing valve D (59) are all connected to the oil tank (51); the A port and the B port of the electromagnetic proportional reversing valve A (56) are respectively connected to the rodless chamber and the rod chamber of the leveling hydraulic cylinder A (60), and are also respectively connected to the two comparison oil ports of the shuttle valve A (72); the oil outlet of the shuttle valve A (72) is connected to the control port of the differential pressure reducing valve A (52); the A port and the B port of the electromagnetic proportional reversing valve B (57) are respectively connected to the leveling hydraulic cylinder A (60) and the rod chamber. The rodless chamber and the rod chamber of the hydraulic cylinder B (61) are connected, and are also connected to the two comparative oil ports of the shuttle valve B (73), respectively. The oil outlet of the shuttle valve B (73) is connected to the control port of the differential pressure reducing valve B (53); the A port and the B port of the electromagnetic proportional reversing valve C (58) are connected to the rodless chamber and the rod chamber of the leveling hydraulic cylinder C (62), respectively. They are also connected to the two comparative oil ports of the shuttle valve C (74), respectively. The oil outlet of the shuttle valve C (74) is connected to the control port of the differential pressure reducing valve C (54); the A port and the B port of the electromagnetic proportional reversing valve D (59) are connected to the rodless chamber and the rod chamber of the leveling hydraulic cylinder D (63), respectively. Two comparison oil ports of the shuttle valve D (75) are connected, and the oil outlet of the shuttle valve D (75) is connected to the control port of the differential pressure reducing valve D (55); the leveling hydraulic cylinder A (60), the leveling hydraulic cylinder B (61), the leveling hydraulic cylinder C (62), and the leveling hydraulic cylinder D (63) are respectively connected with a displacement sensor E (88), a displacement sensor F (89), a displacement sensor G (90), and a displacement sensor H (91) for measuring displacement, and are also respectively connected with an acceleration sensor A (92), an acceleration sensor B (93), an acceleration sensor C (94), and an acceleration sensor D (95) for measuring acceleration; The oil discharge port of the gear pump (48) is also connected to the P ports of the electromagnetic proportional reversing valve E (68), the electromagnetic proportional reversing valve F (69), the electromagnetic proportional reversing valve G (70) and the electromagnetic proportional reversing valve H (71), respectively. The T ports of the electromagnetic proportional reversing valve E (68), the electromagnetic proportional reversing valve F (69), the electromagnetic proportional reversing valve G (70) and the electromagnetic proportional reversing valve H (71) are all connected to the oil tank. The A port of the electromagnetic proportional reversing valve E (68) is connected to the oil tank through the hydraulic oil pump. The control check valve A (76) and the variable throttle valve A (77) are connected to the rodless chamber of the supporting hydraulic cylinder A (64), and the B port thereof is respectively connected to the rod chamber of the supporting hydraulic cylinder A (64) and the hydraulic control port of the hydraulic control check valve A (76); the A port of the electromagnetic proportional reversing valve F (69) is connected to the rodless chamber of the supporting hydraulic cylinder B (65) through the hydraulic control check valve B (78) and the variable throttle valve B (79), and the B port thereof is respectively connected to the rod chamber of the supporting hydraulic cylinder B (65) The A port of the electromagnetic proportional reversing valve G (70) is connected to the rodless chamber of the supporting hydraulic cylinder C (66) through the hydraulic control check valve C (80) and the variable throttle valve C (81), and its B port is connected to the rod chamber of the supporting hydraulic cylinder C (66) and the hydraulic control port of the hydraulic control check valve C (80); the A port of the electromagnetic proportional reversing valve H (71) is connected to the supporting hydraulic cylinder C (66) through the hydraulic control check valve D (82) and the variable throttle valve D (83). The rodless cavity of the supporting hydraulic cylinder D (67) is connected, and its B port is respectively connected to the rod cavity of the supporting hydraulic cylinder D (67) and the hydraulic control port of the hydraulic control check valve D (82); the supporting hydraulic cylinder A (64), the supporting hydraulic cylinder B (65), the supporting hydraulic cylinder C (66), and the supporting hydraulic cylinder D (67) are respectively connected to a displacement sensor A (84), a displacement sensor B (85), a displacement sensor C (86), and a displacement sensor D (87) for measuring displacement; The controller is respectively connected to the horizontal tilt sensor (40), the displacement sensor A (84), the displacement sensor B (85), the displacement sensor C (86), the displacement sensor D (87), the displacement sensor E (88), the displacement sensor F (89), the displacement sensor G (90), the displacement sensor H (91), the acceleration sensor A (92), the acceleration sensor B (93), the acceleration sensor C (94) and the acceleration sensor D (95).

2. A hydraulic system for an automatic leveling test bench according to claim 1, characterized in that: It also comprises four supporting bottom plates (1), which are fixedly connected to the lower ends of the four supporting legs (2), and the supporting bottom plates (1) are square.

3. A hydraulic system for an automatic leveling test bench according to claim 2, characterized in that: The end of the lower cross beam a (5) and the upper end of the supporting leg (2), as well as the end of the lower cross beam b (7) and the upper end of the supporting leg (2) are fixedly connected via a triangular reinforcing plate (3); the middle of the lower cross beam a (5) and the lower part of the supporting leg (2), as well as the middle of the lower cross beam b (7) and the lower part of the supporting leg (2) are fixedly connected via a lower reinforcing rib (6).

4. A hydraulic system for an automatic leveling test bench according to claim 2 or 3, characterized in that: The two sides of the middle part of the top support beam a (32) are fixedly connected to the two upper main beams b (27) through two top support beams b (33).

5. A hydraulic system for an automatic leveling test bench according to claim 4, characterized in that: It also includes four connecting plates d (24) and four connecting plates c (23), wherein the four connecting plates d (24) are respectively fixedly connected to the four corners of the lower end of the upper frame (45), and the four connecting plates c (23) are respectively fixedly connected to the upper ends of the connecting lugs d (22), and the four connecting plates d (24) and the four connecting plates c (23) are fixedly connected by a plurality of connecting bolts (25).

6. A hydraulic system for an automatic leveling test bench according to claim 5, characterized in that: The end of the upper cross beam (12) is provided with a through hole C for the support bolt (11) to pass through, the upper end of the support bolt (11) passes through the through hole C, and is threadedly connected to a nut b (38) and a nut a (37) on the upper and lower sides of the upper cross beam (12).

7. A hydraulic system for an automatic leveling test bench according to claim 6, characterized in that: The oil suction port of the variable pump (47) is connected to the oil tank (51) through a filter A (97), and the oil suction port of the gear pump (48) is connected to the oil tank (51) through a filter B (98); and the T ports of the electromagnetic proportional reversing valve E (68), the electromagnetic proportional reversing valve F (69), the electromagnetic proportional reversing valve G (70) and the electromagnetic proportional reversing valve H (71) are all connected to the oil tank (51) through a cooler (99).

8. A hydraulic system for an automatic leveling test bench according to claim 7, characterized in that: It also includes a counterweight block (96) fixedly connected to the center of the upper end of the support frame (45).

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