Test control system for hydraulic motors

Abstract

This disclosure provides a test control system for a hydraulic motor, comprising a high-pressure pump group, a low-pressure pump group, a pressure regulating valve group, a control valve group, and a winch system. The high-pressure pump group is connected to a first oil port of the motor under test, and the low-pressure pump group is connected to a second oil port of the motor. The pressure regulating valve group is connected to both the high-pressure and low-pressure pump groups. The control valve group is connected to the low-pressure pump group, the high-pressure pump group, the first oil port of the motor, and the second oil port of the motor. The winch system is connected to the motor. This disclosure enables the motor to be tested under pump operating conditions, thereby improving the comprehensiveness of the motor's test data.

Description

Technical Field

[0001] This disclosure belongs to the field of hydraulic control technology, and specifically relates to a test control system for a hydraulic motor. Background Technology

[0002] Before use, hydraulic motors need to be tested to verify whether they meet design specifications, such as pressure, speed, and efficiency.

[0003] In related technologies, when testing hydraulic motors, a test control system is typically used to drive the motor's rotation to check whether it meets the requirements of the actual scenario. The test control system includes a pump set, a directional valve, and a balance valve. The pump set supplies high-pressure oil to the motor, and is connected to the motor via the directional valve and the balance valve. The pump set's return port is connected to the directional valve's inlet port, the directional valve's first working port is connected to the balance valve's inlet port, the balance valve's return port is connected to the motor's inlet port, and the motor's return port is connected to the balance valve's control port and the directional valve's second working port. The directional valve's return port is connected to the oil tank. When the motor needs to rotate forward, the pump set is started, and the high-pressure oil output by the pump set passes through the directional valve and the balance valve before entering the motor. If the motor needs to rotate in reverse, the directional valve is switched.

[0004] However, the above tests only measured the forward and reverse rotation of the motor. The motor was not directly connected to the load, so the motor was always in motor operation mode, that is, the direction of motor rotation was the same as the direction of output torque, which made the test results incomplete. Summary of the Invention

[0005] This disclosure provides a test control system for a hydraulic motor, which can improve the comprehensiveness of real-time data during motor testing. The technical solution is as follows:

[0006] This disclosure provides a test control system for a hydraulic motor, comprising a high-pressure pump group, a low-pressure pump group, a pressure regulating valve group, a control valve group, and a winch system. The control valve group is connected to the low-pressure pump group, the high-pressure pump group, a first oil port of the motor, and a second oil port of the motor. The control valve group is configured to: deliver oil pumped by the high-pressure pump group to the first oil port of the motor, while simultaneously recovering oil output from the second oil port of the motor into an oil tank to drive the motor to rotate forward; or, deliver oil pumped by the low-pressure pump group to the... The second oil port of the motor simultaneously recovers the oil output from the first oil port of the motor into the oil tank to drive the motor in reverse. The pressure regulating valve group is connected to the high-pressure pump group and the low-pressure pump group respectively. The pressure regulating valve group is used to adjust the oil pressure of the oil pumped by the high-pressure pump group to the first oil port of the motor and the oil pressure of the oil pumped by the low-pressure pump group to the second oil port of the motor, so that when the motor rotates forward or in reverse, the oil pressure at the first oil port of the motor is greater than the oil pressure at the second oil port of the motor. The winch system is connected to the motor.

[0007] In another implementation of this disclosure, the high-pressure pump assembly includes a first motor, a first variable pump unit, and a fixed displacement pump; the first motor is connected to both the first variable pump unit and the fixed displacement pump, and the return port of the first variable pump unit is connected to the control valve assembly; the first variable pump unit includes a first pump body, a first variable cylinder, a first shuttle valve, a first displacement control valve, and a first pressure control valve; the rod-side chamber of the first variable cylinder is connected to the variable mechanism of the first pump body, and the rodless chamber of the first variable cylinder is connected to the working port of the first displacement control valve; the first displacement control valve... The oil inlet of the first pressure control valve is connected to the working oil port of the first pressure control valve, and the oil return port of the first displacement control valve is connected to the oil tank; the first oil port of the first shuttle valve is connected to the oil return port of the fixed displacement pump, and the second oil port of the first shuttle valve is connected to the oil return port of the first pump body; the oil inlet of the first pressure control valve is connected to the oil return port of the first shuttle valve, the oil return port of the first pressure control valve is connected to the oil tank, the first control oil port of the first pressure control valve is connected to the pressure regulating valve group, and the second control oil port of the first pressure control valve is connected to the oil return port of the first shuttle valve.

[0008] In another implementation of this disclosure, the pressure regulating valve assembly includes a first proportional pressure reducing valve and a first solenoid directional valve. The inlet of the first proportional pressure reducing valve is connected to the return port of the metering pump, the return port of the first proportional pressure reducing valve is connected to the inlet of the first solenoid directional valve, the control port of the first proportional pressure reducing valve is connected to its own return port, and the drain port of the first proportional pressure reducing valve is connected to the oil tank. The working port of the first solenoid directional valve is connected to the first control port of the first pressure control valve, and the return port of the first solenoid directional valve is connected to the oil tank.

[0009] In another implementation of this disclosure, the low-pressure pump group includes a second motor and a second variable pump unit, the second motor being connected to the second variable pump unit, and the return port of the second variable pump unit being connected to the control valve group; the pressure regulating valve group further includes a second proportional pressure reducing valve and a second solenoid directional valve, the inlet of the second proportional pressure reducing valve being connected to the return port of the fixed displacement pump, the return port of the second proportional pressure reducing valve being connected to the inlet of the second solenoid directional valve, and the control port of the second proportional pressure reducing valve being connected to its own return port; the working port of the second solenoid directional valve is connected to the second variable pump unit, and the return port of the second solenoid directional valve is connected to the oil tank.

[0010] In another implementation of this disclosure, the pressure regulating valve group further includes a control oil overflow valve. The oil inlet of the control oil overflow valve is connected to the oil return port of the metering pump and the first oil port of the first shuttle valve, respectively. The oil return port of the control oil overflow valve is connected to the oil tank, and the control oil port of the control oil overflow valve is connected to its own oil inlet.

[0011] In another implementation of this disclosure, the control valve assembly includes a high-pressure check valve, a high-pressure relief valve unit, a low-pressure check valve, and a low-pressure relief valve unit; the inlet of the high-pressure check valve is connected to the return port of the high-pressure pump assembly, the return port of the high-pressure check valve is connected to its own hydraulic control port, and the return port of the high-pressure check valve is connected to the first port of the motor; the inlet of the high-pressure relief valve unit is connected to the return port of the high-pressure check valve and the first port of the motor, respectively, and the return port of the high-pressure relief valve unit is connected to the inlet of the low-pressure relief valve unit, the second port of the motor, and the return port of the low-pressure check valve, respectively; the high-pressure relief valve unit is configured... The configuration is as follows: when the oil pressure at the inlet of the high-pressure relief valve unit is higher than a first threshold, the oil flowing in from the inlet of the high-pressure relief valve unit will be discharged from the return port of the high-pressure relief valve unit; the inlet of the low-pressure check valve is connected to the return port of the low-pressure pump group, and the hydraulic control port of the low-pressure check valve is connected to its own return port; the return port of the low-pressure relief valve unit is connected to the oil tank, and the low-pressure relief valve unit is configured such that when the oil pressure at the inlet of the low-pressure relief valve unit is higher than a second threshold, the oil flowing in from the inlet of the low-pressure relief valve unit will be discharged from the return port of the low-pressure relief valve unit, wherein the first threshold is greater than the second threshold.

[0012] In another implementation of this disclosure, the high-pressure relief valve unit includes a first control check valve and a first control relief valve. The oil inlet of the first control check valve is connected to the first oil port of the motor and the oil return port of the high-pressure check valve, respectively. The oil return port of the first control check valve is connected to the oil return port of the first control relief valve, the oil inlet of the low-pressure relief valve unit, the oil return port of the low-pressure check valve, and the second oil port of the motor, respectively.

[0013] The control port of the first control check valve is connected to the inlet of the first control relief valve, and the control port of the first control relief valve is connected to its own inlet.

[0014] In another implementation of this disclosure, the control valve group further includes a main control relief valve, the oil inlet of which is connected to the first oil port of the motor and the return oil port of the first control check valve, the return oil port of which is connected to the oil tank, and the control oil port of which is connected to its own oil inlet.

[0015] In another implementation of this disclosure, the test control system further includes a lockout valve assembly, which includes a lockout shuttle valve, a lockout solenoid directional valve, and a lockout cartridge valve. The first port of the lockout shuttle valve is connected to the return port of the high-pressure check valve and the inlet port of the lockout cartridge valve. The second port of the lockout shuttle valve is connected to the first port of the motor. The return port of the lockout shuttle valve is connected to the inlet port of the lockout solenoid directional valve. The return port of the lockout solenoid directional valve is connected to the oil tank. The working port of the lockout solenoid directional valve is connected to the control port of the lockout cartridge valve. The return port of the lockout cartridge valve is connected to the first port of the motor.

[0016] In another implementation of this disclosure, the test control system further includes a safety valve assembly, which includes a safety cartridge valve, a first safety relief valve, a second safety relief valve, and a safety solenoid directional valve. The inlet of the safety cartridge valve is connected to the return port of the locking cartridge valve, the first oil port of the motor, and the inlet of the first safety relief valve. The return port of the safety cartridge valve is connected to the second oil port of the motor and the inlet of the low-pressure relief valve unit. The return port of the first safety relief valve... The inlet of the first safety relief valve is connected to the oil tank; the control port of the first safety relief valve is connected to its own inlet; the inlet of the second safety relief valve is connected to the working port of the second safety solenoid directional valve; the return port of the second safety relief valve is connected to the oil tank; the control port of the second safety relief valve is connected to its own inlet; the inlet of the second safety solenoid directional valve is connected to the control port of the safety cartridge valve and the inlet of the first safety relief valve; and the return port of the second safety solenoid directional valve is connected to the oil tank.

[0017] The beneficial effects of the technical solutions provided in this disclosure are:

[0018] When the test control system provided in this embodiment is used to control the motor, since the test control system includes a winch system and the winch system is connected to the motor, the motor can be made to work according to the actual working conditions by driving the winch to release or retrieve the rope, so as to ensure the comprehensiveness of the test data of the motor.

[0019] Furthermore, since the test control system also includes a high-pressure pump group, a low-pressure pump group, a pressure regulating valve group, and a control valve group, and the control valve group is configured to: deliver the oil pumped by the high-pressure pump group to the first oil port of the motor, while recovering the oil output from the second oil port of the motor into the oil tank to drive the motor to rotate forward; or, deliver the oil pumped by the low-pressure pump group to the second oil port of the motor, while recovering the oil output from the first oil port of the motor into the oil tank to drive the motor to rotate in reverse, the high-pressure pump group can supply oil to the first oil port of the motor to drive the motor to rotate forward, or the low-pressure pump group can supply oil to the second oil port of the motor to drive the motor to rotate in reverse.

[0020] The pressure regulating valve assembly ensures that the oil pressure at the motor's first oil port is greater than the oil pressure at the motor's second oil port when the motor rotates forward or reverse. This allows the motor to operate in a high-pressure state when rotating forward (oil inlet at the first port and return at the second port), with the motor in operation and the winch reeling in the rope. Conversely, when rotating in reverse (oil inlet at the second port and return at the first port), the motor inlet becomes a low-pressure state, and the motor operates in a pump state, with the winch releasing the rope.

[0021] Therefore, the above test control system can put the motor under different operating conditions, thereby conducting comprehensive tests on the motor and ultimately improving the comprehensiveness of the test data. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the principle of a test control system provided in an embodiment of this disclosure;

[0024] Figure 2 yes Figure 1 Enlarged view of the lower middle section;

[0025] Figure 3 yes Figure 2 Enlarged view of the lower left section;

[0026] Figure 4 yes Figure 2 A magnified view of the upper middle section;

[0027] Figure 5 yes Figure 2 Enlarged view of the lower right part;

[0028] Figure 6 yes Figure 1 Enlarged view of the upper right part;

[0029] Figure 7 yes Figure 1 A magnified view of the upper left part.

[0030] The symbols in the diagram represent the following meanings:

[0031] 1. High-pressure pump unit; 11. First motor; 12. First variable pump unit; 120. First pump body; 121. First variable cylinder; 122. First shuttle valve; 123. First displacement control valve; 124. First pressure control valve; 13. Fixed displacement pump;

[0032] 2. Low-pressure pump unit; 21. Second motor; 22. Second variable pump unit; 220. Second pump body; 221. Second variable cylinder; 222. Second shuttle valve; 223. Second displacement control valve; 224. Second pressure control valve;

[0033] 3. Pressure regulating valve assembly; 31. First proportional pressure reducing valve; 32. First solenoid directional valve; 33. Second proportional pressure reducing valve; 34. Second solenoid directional valve; 35. Control oil relief valve;

[0034] 4. Control valve assembly; 41. High-pressure check valve; 42. High-pressure relief valve unit; 421. First control check valve; 422. First control relief valve; 43. Low-pressure check valve; 44. Low-pressure relief valve unit; 45. Speed ​​control valve; 46. Main control relief valve; 47. Pressure reducing valve; 48. First control directional valve; 49. Second control directional valve;

[0035] 5. Locking valve assembly; 51. Locking shuttle valve; 52. Locking solenoid directional valve; 53. Locking cartridge valve;

[0036] 6. Safety valve assembly; 61. Safety cartridge valve; 62. First safety relief valve; 63. Second safety relief valve; 64. Safety solenoid directional valve;

[0037] 100. Motor; 101. Forced large displacement valve; 102. High-frequency response valve; 103. Motor variable displacement cylinder;

[0038] 200. Winch system. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0040] In related technologies, when testing motor 100, only the forward and reverse rotation of motor 100 is detected. Since motor 100 is not directly connected to the load, it is always in motor mode, meaning the rotation direction is the same as the output torque direction. This results in incomplete test results. However, in actual operation, motor 100 can operate in either pump or motor mode. For example, when motor 100 drives a winch to wind up or unwind rope. When the winch winds up, motor 100 needs to rotate forward, operating in motor mode. In this mode, the rotation direction of the motor 100's output shaft is the same as the output torque direction. At this time, oil enters through the first oil port and exits through the second oil port. The first oil port is a high-pressure port. When the winch releases the rope, the rope's gravity causes it to pull the motor 100 to rotate in the opposite direction. At this time, the motor 100 needs to pull the rope to prevent overspeed during its descent. Therefore, the motor 100 operates in pump mode, with the output shaft rotating in the opposite direction to the output torque. Oil enters through the second port of the motor 100 and exits through the first port. The first port is a high-pressure port. However, because oil enters through the second port and exits through the first port, the existing testing systems in related technologies cannot achieve the above objectives. Therefore, additional valves are needed to control the oil pressure at the first port to be greater than that at the second port. Therefore, this disclosure proposes a testing and control system for the hydraulic motor 100 that differs from those in related technologies to solve the above problems.

[0041] Figure 1 This is a schematic diagram of a test control system provided in an embodiment of this disclosure, as shown below. Figure 1 As shown, the test control system includes a high-pressure pump group 1, a low-pressure pump group 2, a pressure regulating valve group 3, a control valve group 4, and a winch system 200. The control valve group 4 is connected to the low-pressure pump group 2, the high-pressure pump group 1, the first oil port of the motor 100, and the second oil port of the motor 100, respectively.

[0042] The control valve assembly 4 is configured such that, when the motor 100 rotates forward, the high-pressure pump assembly 1 pumps oil into the first port of the motor 100, while simultaneously recovering the oil from the second port of the motor 100 into the oil tank; or, when the motor 100 rotates in reverse, the low-pressure pump assembly 2 pumps oil into the second port of the motor 100, while simultaneously recovering the oil from the first port of the motor 100 into the oil tank. The pressure regulating valve assembly 3 is connected to both the high-pressure pump assembly 1 and the low-pressure pump assembly 2. The pressure regulating valve assembly 3 is used to adjust the oil pressure pumped by the high-pressure pump assembly 1 into the first port of the motor 100 and to adjust the oil pressure pumped by the low-pressure pump assembly 2 into the second port of the motor 100, so that the oil pressure at the first port of the motor 100 is greater than the oil pressure at the second port of the motor 100 when the motor 100 rotates forward or in reverse. The winch system 200 is connected to the motor 100.

[0043] When the test control system provided in this embodiment is used to control the motor 100, since the test control system includes a winch system 200 and the winch system 200 is connected to the motor 100, the motor 100 can be made to work according to the actual working conditions by driving the winch to release or retrieve the rope, so as to ensure the comprehensiveness of the test data of the motor.

[0044] Furthermore, since the test control system also includes a high-pressure pump group 1, a low-pressure pump group 2, a pressure regulating valve group 3, and a control valve group 4, and the control valve group 4 is configured to: deliver the oil pumped by the high-pressure pump group 1 to the first oil port of the motor 100, while simultaneously recovering the oil output from the second oil port of the motor 100 into the oil tank, so as to drive the motor 100 to rotate forward; or, deliver the oil pumped by the low-pressure pump group 2 to the second oil port of the motor 100, while simultaneously recovering the oil output from the first oil port of the motor 100 into the oil tank, so as to drive the motor 100 to rotate in reverse, the high-pressure pump group 1 can supply oil to the first oil port of the motor to drive the motor 100 to rotate forward, or the low-pressure pump group 2 can supply oil to the second oil port of the motor 100 to drive the motor 100 to rotate in reverse.

[0045] Because the pressure regulating valve group 3 ensures that the oil pressure at the first oil port of motor 100 is greater than the oil pressure at the second oil port when motor 100 rotates forward or reverse, oil can enter through the first oil port and exit through the second oil port when motor 100 rotates forward. In this case, the oil inlet of motor 100 is a high-pressure port, and motor 100 is in motor operation mode, with the winch reeling in the rope. Conversely, when motor 100 rotates in reverse, oil enters through the second oil port and exits through the first oil port. In this case, the oil inlet of motor 100 is a low-pressure port, and motor 100 is in pump operation mode, with the winch releasing the rope.

[0046] Therefore, the above test control system can put the motor 100 under different operating conditions, thereby conducting comprehensive tests on the motor 100 and ultimately improving the comprehensiveness of the test data.

[0047] Figure 2 yes Figure 1 Enlarged view of the lower middle section, such as Figure 2 As shown, optionally, the high-pressure pump unit 1 includes a first motor 11, a first variable pump unit 12, and a fixed displacement pump 13. The first motor 11 is connected to the first variable pump unit 12 and the fixed displacement pump 13 respectively, and the return port of the first variable pump unit 12 is connected to the control valve group 4.

[0048] Figure 3 yes Figure 2 The enlarged image in the lower left corner, combined with Figure 3The first variable pump unit 12 includes a first pump body 120, a first variable cylinder 121, a first shuttle valve 122, a first displacement control valve 123, and a first pressure control valve 124. The rod-side chamber of the first variable cylinder 121 is connected to the variable mechanism of the first pump body 120, and the rodless chamber of the first variable cylinder 121 is connected to the working port of the first displacement control valve 123. The inlet port of the first displacement control valve 123 is connected to the working port of the first pressure control valve 124, and the return port of the first displacement control valve 123 is connected to the oil tank. The first port of the first shuttle valve 122 is connected to the return port of the fixed displacement pump 13, and the second port of the first shuttle valve 122 is connected to the return port of the first pump body 120. The oil inlet of the first pressure control valve 124 is connected to the oil return port of the first shuttle valve 122. The oil return port of the first pressure control valve 124 is connected to the oil tank. The first control port of the first pressure control valve 124 is connected to the working port of the first solenoid directional valve 32. The second control port of the first pressure control valve 124 is connected to the oil return port of the first shuttle valve 122.

[0049] In the above implementation, the first motor 11 drives the first variable pump unit 12 and the fixed displacement pump 13. The first variable pump unit 12 pumps high-pressure oil to the first oil port A of the motor 100. The fixed displacement pump 13 provides control oil to the pressure regulating valve assembly 3.

[0050] The first displacement control valve 123 is used to adjust the maximum displacement of the first pump body 120, and the first pressure control valve 124 is used to adjust the maximum working pressure of the first pump body 120.

[0051] Under normal conditions, the right-side spring force of the first displacement control valve 123 is greater than the left-side spring force, and the first displacement control valve 123 operates in the right position. The working port A of the first displacement control valve 123 is connected to the return port T, A→T. Oil in the rodless chamber of the first variable cylinder 121 is discharged through the working port A→return port T of the first displacement control valve 123. Under the pull of the left-side spring of the first displacement control valve 123, the piston of the first variable cylinder 121 is at its leftmost position, and the first pump body 120 is at its maximum displacement.

[0052] When the first motor 11 starts, the pressurized oil in the return port of the first pump body 120 enters the rod chamber of the first variable cylinder 121 directly; the other path of the pressurized oil in the return port of the first pump body 120 passes through the first pressure control valve 124 and the first displacement control valve 123 in sequence before entering the rodless chamber of the first variable cylinder 121. Therefore, when there is no control signal from either the first pressure control valve 124 or the first displacement control valve 123, both valves operate in the right position. The inlet P of the first pressure control valve 124 is connected to the working port A, and the working port A of the first displacement control valve 123 is connected to the return port T. The oil in the rodless chamber of the first variable cylinder 121 is discharged into the oil tank. The piston rod of the first variable cylinder 121 retracts into the cylinder body. The first pump body 120 is in standby mode at minimum displacement. When the first displacement control valve 123 receives a signal, it operates in the left position. The larger the control signal of the first displacement control valve 123, the larger the connection opening between the oil inlet P and the working oil port A of the first displacement control valve 123. Correspondingly, the flow rate of the oil entering the rodless chamber of the first variable cylinder 121 is greater, and the maximum displacement of the first pump body 120 is greater. That is, the first displacement control valve 123 determines the maximum displacement of the first pump body 120.

[0053] When the return port pressure of the first pump body 120 is less than the set value of the first pressure control valve 124, the first pressure control valve 124 operates in the right position, and the opening between the inlet P and the working port A of the first pressure control valve 124 is at its maximum (P→A of the first pressure control valve 124 is fully open), and the first pump body 120 operates at its maximum displacement. When the return port pressure of the first pump body 120 reaches the set value of the first pressure control valve 124, the first pressure control valve 124 operates in the left position, the opening between the inlet P and the working port A of the first pressure control valve 124 becomes smaller, while the opening between A and T becomes larger, the first pump body 120 changes direction, the output flow rate adapts to the system's required flow rate, and the return port oil pressure of the first pump body 120 remains unchanged.

[0054] The second control port X2 and the first control port X1 of the first pressure control valve 124 are connected to the return port C of the first shuttle valve 122 and the pressure regulating valve group 3, respectively. The pressure at the first port A of the first shuttle valve 122 is connected to the return port of the fixed displacement pump 13, and the second port of the first shuttle valve 122 is connected to the return port of the first pump body 120. Therefore, the pressure at the return port C of the first shuttle valve 122 is always higher than the pressure at the first port A and the second port B.

[0055] In this embodiment, the hydraulic pressure application area of ​​the first control port X1 of the first pressure control valve 124 is much larger than that of the second control port X2. That is, the set value of the first pressure control valve 124 depends primarily on the pressure at the first control port X1 of the first pressure control valve 124, which is also dependent on the pressure of the pressure regulating valve assembly 3.

[0056] Figure 4 yes Figure 2 The enlarged image in the upper middle section, combined with Figure 4 Optionally, the pressure regulating valve assembly 3 includes a first proportional pressure reducing valve 31 and a first solenoid directional valve 32. The inlet of the first proportional pressure reducing valve 31 is connected to the return port of the fixed displacement pump 13, and the return port of the first proportional pressure reducing valve 31 is connected to the inlet of the first solenoid directional valve 32. The control port of the first proportional pressure reducing valve 31 is connected to its own return port. The drain port of the first proportional pressure reducing valve 31 is connected to the oil tank. The working port of the first solenoid directional valve 32 is connected to the first control port of the first pressure control valve 124, used to control the output pressure and displacement of the first pump body 120. The return port of the first solenoid directional valve 32 is connected to the oil tank.

[0057] The first proportional pressure reducing valve 31 is used to regulate the output pressure and displacement of the first pump body 120. Since the minimum adjustable pressure of the first proportional pressure reducing valve 31 is non-zero, in order to reduce the minimum set pressure of the first pump body 120 and improve safety and energy efficiency during testing, a first electromagnetic directional valve 32 is installed at the return port of the first proportional pressure reducing valve 31. When the first electromagnetic directional valve 32 is energized, it operates in the right position, and its inlet P is connected to its working port A (P→A), allowing the first proportional pressure reducing valve 31 to adjust the pressure. When the first electromagnetic directional valve 32 is de-energized, it operates in the left position, and the oil at the first control port X1 of the first pressure control valve 124 is discharged through the working port A→return port T of the first electromagnetic directional valve 32, resulting in the lowest set pressure for the first variable pump unit 12.

[0058] Combination Figure 2 Optionally, the low-pressure pump group 2 includes a second motor 21 and a second variable pump unit 22. The second motor 21 is connected to the second variable pump unit 22, and the oil return port of the second variable pump unit 22 is connected to the control valve group 4.

[0059] Combination Figure 4 The pressure regulating valve assembly 3 also includes a second proportional pressure reducing valve 33 and a second solenoid directional valve 34. The inlet of the second proportional pressure reducing valve 33 is connected to the return port of the fixed displacement pump 13, and the return port of the second proportional pressure reducing valve 33 is connected to the inlet of the second solenoid directional valve 34. The control port of the second proportional pressure reducing valve 33 is connected to its own return port. The working port of the second solenoid directional valve 34 is connected to the second variable pump unit 22 to control the output pressure and displacement of the second variable pump unit 22. The return port of the second solenoid directional valve 34 is connected to the oil tank.

[0060] In the above implementation, the second motor 21 drives the second variable pump unit 22. The second variable pump unit 22 pumps pressurized oil to the second port B of the motor 100. The second proportional pressure reducing valve 33 adjusts the output pressure and displacement of the second variable pump unit 22.

[0061] The working principle of the low-pressure pump group 2 is similar to that of the high-pressure pump group 1, and will not be described again here.

[0062] Optionally, the pressure regulating valve assembly 3 also includes a control oil overflow valve 35. The oil inlet of the control oil overflow valve 35 is connected to the oil return port of the metering pump 13, the first oil port of the first shuttle valve 122, and the second oil port of the second shuttle valve 222. The oil return port of the control oil overflow valve 35 is connected to the oil tank, and the control oil port of the control oil overflow valve 35 is connected to its own oil inlet.

[0063] When the return oil pressure of the first pump body 120 is less than the set pressure of the control oil overflow valve 35 (e.g., 3.5MPa) (e.g., when the high-pressure pump is in low-pressure standby mode), the first oil port of the first shuttle valve 122 is connected to the return oil port, and the oil path in the first shuttle valve 122 is A→C. The oil in the return oil port of the first pump body 120 enters the rod chamber of the first variable cylinder 121, so that the first pump body 120 quickly returns to the minimum displacement standby mode, saving energy and reducing consumption.

[0064] Figure 5 yes Figure 2 The enlarged image in the lower right corner, combined with Figure 5 Optionally, the second variable pump unit 22 includes a second pump body 220, a second variable cylinder 221, a second shuttle valve 222, a second displacement control valve 223, and a second pressure control valve 224. The rod-side chamber of the second variable cylinder 221 is connected to the variable mechanism of the second pump body 220, and the rodless chamber of the second variable cylinder 221 is connected to the working port of the second displacement control valve 223. The inlet port of the second displacement control valve 223 is connected to the working port of the second pressure control valve 224, and the return port of the second displacement control valve 223 is connected to the oil tank. The second port of the second shuttle valve 222 is connected to the return port of the fixed displacement pump 13, and the second port of the second shuttle valve 222 is connected to the return port of the second pump body 220. The oil inlet of the second pressure control valve 224 is connected to the oil return port of the second shuttle valve 222. The oil return port of the second pressure control valve 224 is connected to the oil tank. The first control port of the second pressure control valve 224 is connected to the working port of the second solenoid directional valve 34. The second control port of the second pressure control valve 224 is connected to the oil return port of the second shuttle valve 222.

[0065] The second variable pump unit 22 has the same structure as the first variable pump unit 12. The working principle of the second variable pump unit 22 can be found in the first variable pump unit 12 mentioned above, and will not be repeated here.

[0066] Figure 6 yes Figure 1 The enlarged image in the upper right corner, combined with Figure 6 Optionally, the control valve assembly 4 includes a high-pressure check valve 41, a high-pressure relief valve unit 42, a low-pressure check valve 43, and a low-pressure relief valve unit 44. The oil inlet of the high-pressure check valve 41 is connected to the oil return port of the high-pressure pump assembly 1, the oil return port of the high-pressure check valve 41 is connected to its own hydraulic control port, and the oil return port of the high-pressure check valve 41 is connected to the first oil port of the motor 100.

[0067] The oil inlet of the high-pressure relief valve unit 42 is connected to the oil return port of the high-pressure check valve 41 and the first oil port of the motor 100, respectively. The oil return port of the high-pressure relief valve unit 42 is connected to the oil inlet of the low-pressure relief valve unit 44, the second oil port of the motor 100 and the oil return port of the low-pressure check valve 43, respectively. The high-pressure relief valve unit 42 is configured such that when the oil pressure of the oil inlet of the high-pressure relief valve unit 42 is higher than the first threshold, the oil flowing in from the oil inlet of the high-pressure relief valve unit 42 will be discharged from the oil return port of the high-pressure relief valve unit 42.

[0068] The inlet of the low-pressure check valve 43 is connected to the return port of the low-pressure pump group 2, and the hydraulic control port of the low-pressure check valve 43 is connected to its own return port.

[0069] The return port of the low-pressure relief valve unit 44 is connected to the oil tank. The low-pressure relief valve unit 44 is configured such that when the oil pressure at the oil inlet of the low-pressure relief valve unit 44 reaches the second threshold, the oil flowing in from the oil inlet of the low-pressure relief valve unit 44 will be discharged from the return port of the low-pressure relief valve unit 44. The first threshold is greater than the second threshold.

[0070] In the above implementation, the high-pressure check valve 41 is used to prevent high-pressure oil from flowing back into the first pump body 120 and damaging or causing the first pump body 120 to reverse when oil returns from the first oil port A of the motor 100. The high-pressure relief valve unit 42 serves as a safety valve, and its set pressure is always higher than the maximum pressure corresponding to the first pressure control valve 124. The low-pressure check valve 43 is used to prevent low-pressure oil from flowing back into the second pump body 220 and damaging or causing the second pump body 220 to reverse when oil returns from the second oil port B of the motor 100. The low-pressure relief valve unit 44 serves as a safety valve, and its set pressure is always higher than the maximum pressure corresponding to the second pressure control valve 224.

[0071] Optionally, the high-pressure relief valve unit 42 includes a first control check valve 421 and a first control relief valve 422. The oil inlet of the first control check valve 421 is connected to the first oil port A of the motor 100 and the oil return port of the high-pressure check valve 41, respectively. The oil return port of the first control check valve 421 is connected to the oil return port of the first control relief valve 422, the oil inlet of the low-pressure relief valve unit 44, the oil return port of the low-pressure check valve 43, and the second oil port of the motor 100, respectively. The control oil port of the first control check valve 421 is connected to the oil inlet of the first control relief valve 422, the oil return port of the first control relief valve 422 is connected to the oil return port of the first control check valve 421, and the control oil port of the first control relief valve 422 is connected to its own oil inlet.

[0072] In the above-mentioned rope release process, the first control check valve 421 is used to limit the flow direction of the oil, and the first control relief valve 422 is used to limit the pressure when the first oil port A of the motor 100 returns oil.

[0073] The low-pressure relief valve unit 44 has the same structure as the high-pressure relief valve unit 42, so it will not be described again here.

[0074] Optionally, the control valve group 4 also includes a speed control valve 45 and a main control relief valve 46. The oil inlet of the speed control valve 45 is connected to the first oil port of the motor 100 and the oil inlet of the first control check valve 421, respectively. The oil return port of the speed control valve 45 is connected to the oil inlet of the main control relief valve 46. The oil return port of the main control relief valve 46 is connected to the oil tank. The control oil port of the main control relief valve 46 is connected to its own oil inlet.

[0075] In the above implementation, the speed control valve 45 is used to limit the maximum flow rate into the main control relief valve 46 to prevent it from exceeding the operating range of the main control relief valve 46 and causing pressure regulation failure. The main control relief valve 46 is used to adjust the relief pressure of the brake control oil circuit.

[0076] Optionally, the control valve group 4 further includes a pressure reducing valve 47, a first control directional valve 48, and a second control directional valve 49. The oil inlet of the pressure reducing valve 47 is connected to the oil return port of the speed regulating valve 45 and the oil inlet of the main control relief valve 46, respectively. The oil return port of the pressure reducing valve 47 is connected to the oil inlet of the first control directional valve 48, and the control port of the pressure reducing valve 47 is connected to its own oil return port.

[0077] The return port of the first control directional valve 48 is connected to the oil tank, the working port of the first control directional valve 48 is connected to the inlet port of the second control directional valve 49, the return port of the second control directional valve 49 is connected to the oil tank, and the working port of the second control directional valve 49 is connected to the rod chamber of the cylinder used to drive the brake to open.

[0078] The brake is used to brake the output shaft of motor 100.

[0079] Pressure reducing valve 47 is used to reduce the pressure of the control oil in the brake. First control directional valve 48 and second control directional valve 49 are used to control the opening and closing of the brake. When both solenoid directional valves are energized, control oil enters the brake, and the brake opens; when one of the first control directional valve 48 or the second control directional valve 49 is de-energized, the control oil is depressurized, and the brake automatically closes to improve safety.

[0080] Figure 7 yes Figure 1 The enlarged image in the upper left corner, combined with Figure 7 Optionally, the test control system further includes a lockout valve assembly 5, which includes a lockout shuttle valve 51, a lockout solenoid directional valve 52, and a lockout cartridge valve 53. The first port of the lockout shuttle valve 51 is connected to the return port of the high-pressure check valve 41 and the inlet port of the lockout cartridge valve 53. The second port of the lockout shuttle valve 51 is connected to the first port of the motor 100. The return port of the lockout shuttle valve 51 is connected to the inlet port of the lockout solenoid directional valve 52. The return port of the lockout solenoid directional valve 52 is connected to the oil tank. The working port of the lockout solenoid directional valve 52 is connected to the control port of the lockout cartridge valve 53. The return port of the lockout cartridge valve 53 is connected to the first port of the motor 100.

[0081] In the above implementation, the locking valve group 5 is used to lock the motor 100, so that the motor 100 can be braked in an emergency.

[0082] The locking solenoid directional valve 52 controls whether the locking cartridge valve 53 is open. The first port A of the locking shuttle valve 51 is connected to the return port of the high-pressure check valve 41, and the second port B of the locking shuttle valve 51 is connected to the first port A of the motor 100. The oil pressure at the return port C of the locking shuttle valve 51 is always the higher pressure of the first port A and the second port B. When the locking solenoid directional valve 52 is de-energized, the locking cartridge valve 53 closes, locking the motor 100 and preventing the winch from winding or unwinding the rope. When the locking solenoid directional valve 52 is energized, the locking cartridge valve 53 opens, allowing the motor 100 to rotate.

[0083] Optionally, the test control system also includes a safety valve assembly 6, which includes a safety cartridge valve 61, a first safety relief valve 62, a second safety relief valve 63, and a safety solenoid directional valve 64.

[0084] The inlet of safety cartridge valve 61 is connected to the return port of locking cartridge valve 53, the first port of motor 100, and the inlet of safety first relief valve 62. The return port of safety cartridge valve 61 is connected to the second port of motor 100 and the inlet of low-pressure relief valve unit 44. The return port of safety first relief valve 62 is connected to the oil tank, and the control port of safety first relief valve 62 is connected to its own inlet. The inlet of safety second relief valve 63 is connected to the working port of safety solenoid directional valve 64. The return port of safety second relief valve 63 is connected to the oil tank, and the control port of safety second relief valve 63 is connected to its own inlet. The inlet of safety solenoid directional valve 64 is connected to the control port of safety cartridge valve 61 and the inlet of safety first relief valve 62. The return port of safety solenoid directional valve 64 is connected to the oil tank.

[0085] In the above implementation, when the safety solenoid directional valve 64 is de-energized, the set pressure depends on the first safety relief valve 62; when the safety solenoid directional valve 64 is energized, the set pressure depends on the second safety relief valve 63.

[0086] In this embodiment, to further improve the response speed of the motor 100, the motor 100 is also connected to a forced high-displacement valve 101, a high-frequency response valve 102, and a motor variable cylinder 103. The oil inlet P of the high-frequency response valve 102 is connected to the oil inlet A of the lock-up cartridge valve 53, and the oil return port T of the high-frequency response valve 102 is connected to the second oil port B of the motor 100. The first working oil port A and the second working oil port B of the high-frequency response valve 102 are respectively connected to the two oil inlets of the forced high-displacement valve 101. The two oil return ports of the forced high-displacement valve 101 are respectively connected to the two oil chambers of the motor variable cylinder 103. The other two oil inlets of the forced high-displacement valve 101 are respectively connected to the second oil port B of the motor 100 and the oil return port C of the lock-up shuttle valve 51. The piston rod of the motor variable cylinder 103 is connected to the motor 100.

[0087] The following is a brief description of the working process of the control system provided in the embodiments of this disclosure:

[0088] 1) Winch rope winding:

[0089] The first pump body 120 and the second pump body 220 are driven, the first solenoid directional valve 32 and the second solenoid directional valve 34 are energized, the first proportional pressure reducing valve 31 controls the set pressure of the first pump body 120, and the second proportional pressure reducing valve 33 controls the set pressure of the second pump body 220.

[0090] High-pressure oil from the return port of the first pump body 120 passes through the high-pressure check valve 41 to the inlet A of the lock-up cartridge valve 53. The lock-up solenoid directional valve 52 is energized, and the lock-up cartridge valve 53 opens. The high-pressure oil then reaches the first port A of the motor 100.

[0091] The high-pressure oil from the return port of the second pump body 220 passes through the low-pressure check valve 43 and directly reaches the second oil port B of the motor 100. At this time, the pressure difference between the first oil port A and the second oil port B of the motor 100 is constant and depends on the set pressure difference between the first pump body 120 and the second pump body 220. Changing the displacement of the motor 100 can change the output torque of the motor 100.

[0092] The forced large displacement valve 101 of motor 100 is energized, connecting the high-frequency response valve 102 to the motor variable cylinder 103. Controlling the high-frequency response valve 102 to reverse direction and changing the motor variable cylinder 103 alters the displacement of motor 100, making the output torque of motor 100 slightly greater than the load requirement torque. At this time, the first control reversing valve 48 and the second control reversing valve 49 are energized, the control oil opens the brake, oil enters through the first oil port A of motor 100 and returns through the second oil port B, driving the winch to wind up the rope.

[0093] 2) Loosening the rope by winch

[0094] The high-frequency reversing valve 102 is controlled to switch, and the displacement of the motor 100 is changed through the motor variable cylinder 103, so that the output torque of the motor 100 is slightly less than the torque required by the load. At this time, the first control reversing valve 48 and the second control reversing valve 49 are energized, the control oil opens the brake, oil enters through the second oil port B of the motor 100 and returns through the first oil port A, the motor 100 operates in pump mode, and the winch releases the rope.

[0095] 3) Motor 100 and winch emergency stop impact test

[0096] When the winch releases the rope, the system experiences an emergency power outage. The first pump body 120 and the second pump body 220 stop supplying oil. At this time, the forced high-displacement valve 101 is de-energized, and the high-pressure oil at the return port C of the locking shuttle valve 51 directly enters the variable displacement cylinder 103 of the motor, causing the motor 100 to reach its maximum displacement to support the load. Additionally, the first control directional valve 48 and the second control directional valve 49 are de-energized, the brake control oil is depressurized, and the brake automatically closes to ensure safety.

[0097] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A test control system for a hydraulic motor, characterized in that, The test control system includes a high-pressure pump group (1), a low-pressure pump group (2), a pressure regulating valve group (3), a control valve group (4), and a winch system (200). The control valve group (4) is connected to the low-pressure pump group (2), the high-pressure pump group (1), the first oil port of the motor (100), and the second oil port of the motor (100), respectively. The control valve group (4) is configured to: deliver the oil pumped by the high-pressure pump group (1) to the first oil port of the motor (100), and at the same time recover the oil output from the second oil port of the motor (100) into the oil tank to drive the motor (100) to rotate forward; or, deliver the oil pumped by the low-pressure pump group (2) to the second oil port of the motor (100), and at the same time recover the oil output from the first oil port of the motor (100) into the oil tank to drive the motor (100) to rotate in reverse. The control valve group (4) includes a high-pressure check valve (41), a high-pressure relief valve unit (42), a low-pressure check valve (43), and a low-pressure relief valve unit (44). The inlet of the high-pressure check valve (41) is connected to the return port of the high-pressure pump group (1), the return port of the high-pressure check valve (41) is connected to its own hydraulic control port, the return port of the high-pressure check valve (41) is connected to the first port of the motor (100), the inlet of the high-pressure relief valve unit (42) is connected to the return port of the high-pressure check valve (41) and the first port of the motor (100), the return port of the high-pressure relief valve unit (42) is connected to the inlet of the low-pressure relief valve unit (44), the second port of the motor (100) and the return port of the low-pressure check valve (43), and the high-pressure relief valve unit (42) is configured such that: when the inlet of the high-pressure relief valve unit (42) is... When the oil pressure of the oil is higher than the first threshold, the oil flowing in from the inlet of the high pressure relief valve unit (42) will be discharged from the return port of the high pressure relief valve unit (42). The inlet of the low pressure check valve (43) is connected to the return port of the low pressure pump group (2). The hydraulic control port of the low pressure check valve (43) is connected to its own return port. The return port of the low pressure relief valve unit (44) is connected to the oil tank. The low pressure relief valve unit (44) is configured such that when the oil pressure of the oil at the inlet of the low pressure relief valve unit (44) is higher than the second threshold, the oil flowing in from the inlet of the low pressure relief valve unit (44) will be discharged from the return port of the low pressure relief valve unit (44). The first threshold is greater than the second threshold. The pressure regulating valve group (3) is connected to the high-pressure pump group (1) and the low-pressure pump group (2) respectively. The pressure regulating valve group (3) is used to adjust the oil pressure of the oil pumped by the high-pressure pump group (1) to the first oil port of the motor (100) and to adjust the oil pressure of the oil pumped by the low-pressure pump group (2) to the second oil port of the motor (100) so that when the motor (100) rotates forward or reverse, the oil pressure at the first oil port of the motor (100) is greater than the oil pressure at the second oil port of the motor (100). The winch system (200) is connected to the motor (100).

2. The test control system according to claim 1, characterized in that, The high-pressure pump set (1) includes a first motor (11), a first variable pump unit (12), and a fixed displacement pump (13). The first motor (11) is connected to the first variable pump unit (12) and the fixed displacement pump (13) respectively, and the oil return port of the first variable pump unit (12) is connected to the control valve group (4); The first variable pump unit (12) includes a first pump body (120), a first variable cylinder (121), a first shuttle valve (122), a first displacement control valve (123), and a first pressure control valve (124). The rod chamber of the first variable cylinder (121) is connected to the variable mechanism of the first pump body (120), the rodless chamber of the first variable cylinder (121) is connected to the working port of the first displacement control valve (123), the inlet of the first displacement control valve (123) is connected to the working port of the first pressure control valve (124), and the return port of the first displacement control valve (123) is connected to the oil tank. The first oil port of the first shuttle valve (122) is connected to the return oil port of the metering pump (13), and the second oil port of the first shuttle valve (122) is connected to the return oil port of the first pump body (120). The inlet of the first pressure control valve (124) is connected to the return port of the first shuttle valve (122), the return port of the first pressure control valve (124) is connected to the oil tank, the first control port of the first pressure control valve (124) is connected to the pressure regulating valve group (3), and the second control port of the first pressure control valve (124) is connected to the return port of the first shuttle valve (122).

3. The test control system according to claim 2, characterized in that, The pressure regulating valve group (3) includes a first proportional pressure reducing valve (31) and a first electromagnetic reversing valve (32). The oil inlet of the first proportional pressure reducing valve (31) is connected to the oil return port of the metering pump (13). The oil return port of the first proportional pressure reducing valve (31) is connected to the oil inlet of the first electromagnetic reversing valve (32). The control oil port of the first proportional pressure reducing valve (31) is connected to its own oil return port. The oil drain port of the first proportional pressure reducing valve (31) is connected to the oil tank. The working port of the first electromagnetic directional valve (32) is connected to the first control port of the first pressure control valve (124), and the return port of the first electromagnetic directional valve (32) is connected to the oil tank.

4. The test control system according to claim 3, characterized in that, The low-pressure pump group (2) includes a second motor (21) and a second variable pump unit (22). The second motor (21) is connected to the second variable pump unit (22), and the oil return port of the second variable pump unit (22) is connected to the control valve group (4). The pressure regulating valve group (3) also includes a second proportional pressure reducing valve (33) and a second electromagnetic reversing valve (34). The oil inlet of the second proportional pressure reducing valve (33) is connected to the oil return port of the metering pump (13). The oil return port of the second proportional pressure reducing valve (33) is connected to the oil inlet of the second electromagnetic reversing valve (34). The control oil port of the second proportional pressure reducing valve (33) is connected to its own oil return port. The working port of the second electromagnetic directional valve (34) is connected to the second variable pump unit (22), and the return port of the second electromagnetic directional valve (34) is connected to the oil tank.

5. The test control system according to claim 4, characterized in that, The pressure regulating valve group (3) also includes a control oil overflow valve (35). The oil inlet of the control oil overflow valve (35) is connected to the oil return port of the metering pump (13) and the first oil port of the first shuttle valve (122). The oil return port of the control oil overflow valve (35) is connected to the oil tank. The control oil port of the control oil overflow valve (35) is connected to its own oil inlet.

6. The test control system according to claim 1, characterized in that, The high-pressure relief valve unit (42) includes a first control check valve (421) and a first control relief valve (422). The oil inlet of the first control check valve (421) is connected to the first oil port of the motor (100) and the oil return port of the high-pressure check valve (41). The oil return port of the first control check valve (421) is connected to the oil return port of the first control relief valve (422), the oil inlet of the low-pressure relief valve unit (44), the oil return port of the low-pressure check valve (43), and the second oil port of the motor (100). The control port of the first control check valve (421) is connected to the inlet of the first control relief valve (422), and the control port of the first control relief valve (422) is connected to its own inlet.

7. The test control system according to claim 6, characterized in that, The control valve group (4) also includes a main control relief valve (46). The oil inlet of the main control relief valve (46) is connected to the first oil port of the motor (100) and the oil inlet of the first control check valve (421). The oil return port of the main control relief valve (46) is connected to the oil tank. The control oil port of the main control relief valve (46) is connected to its own oil inlet.

8. The test control system according to claim 1, characterized in that, The test control system also includes a lockout valve assembly (5), which further includes a lockout shuttle valve (51), a lockout solenoid directional valve (52), and a lockout cartridge valve (53). The first oil port of the locking shuttle valve (51) is connected to the return oil port of the high-pressure check valve (41) and the inlet oil port of the locking cartridge valve (53). The second oil port of the locking shuttle valve (51) is connected to the first oil port of the motor (100). The return oil port of the locking shuttle valve (51) is connected to the inlet oil port of the locking solenoid directional valve (52). The return oil port of the locking solenoid directional valve (52) is connected to the oil tank. The working oil port of the locking solenoid directional valve (52) is connected to the control oil port of the locking cartridge valve (53). The return oil port of the locking cartridge valve (53) is connected to the first oil port of the motor (100).

9. The test control system according to claim 8, characterized in that, The test control system also includes a safety valve group (6), which includes a safety cartridge valve (61), a first safety relief valve (62), a second safety relief valve (63), and a safety solenoid directional valve (64). The oil inlet of the safety cartridge valve (61) is connected to the oil return port of the locking cartridge valve (53), the first oil port of the motor (100), and the oil inlet of the first safety relief valve (62), respectively. The oil return port of the safety cartridge valve (61) is connected to the second oil port of the motor (100) and the oil inlet of the low-pressure relief valve unit (44), respectively. The return port of the first safety relief valve (62) is connected to the oil tank, and the control port of the first safety relief valve (62) is connected to its own inlet. The oil inlet of the second safety relief valve (63) is connected to the working oil port of the safety solenoid directional valve (64), the oil return port of the second safety relief valve (63) is connected to the oil tank, and the control oil port of the second safety relief valve (63) is connected to its own oil inlet. The oil inlet of the safety solenoid directional valve (64) is connected to the control oil port of the safety cartridge valve (61) and the oil inlet of the safety first relief valve (62), and the oil return port of the safety solenoid directional valve (64) is connected to the oil tank.

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