Multi-speed continuously variable hydraulic system for rotary drive, rotary drive mechanism

Abstract

This invention discloses a multi-gear stepless speed-regulating hydraulic system and a rotary drive mechanism for rotary drives. It comprises a gear-switching valve group, a first hydraulic control valve group, a second hydraulic control valve group, a third hydraulic control valve group, and four motors, providing three gear control levels: low-speed high-torque drive, medium-speed medium-torque drive, and high-speed low-torque drive. This enables wide torque and speed output. Furthermore, the main control valve group achieves low-power standby control and stepless motor speed adjustment at any gear, meeting the precise speed control requirements of the rotary drive mechanism. It also automatically enters low-power consumption mode during standby, significantly reducing operating energy costs. Moreover, proportional control is achieved only through the main control valve group, with the remaining valve groups using hydraulic control valves, eliminating the need for complex sensors and control programs, greatly reducing system control complexity, application costs, and failure rates.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rotary drive, in particular, to a multi-gear stepless speed regulation hydraulic system for rotary drive, and further relates to a rotary drive mechanism using the multi-gear stepless speed regulation hydraulic system. BACKGROUND

[0002] With the development of large-scale excavators, shield cutter systems, tunnel assembly machines, anchor drills, fire ladders, high-altitude working vehicles, concrete pump trucks, horizontal directional drills, cranes, anchor drills and other engineering machinery, the industry demand for the rotary mechanism of the products has put forward higher, more complex and diverse demands, and the rotary transmission system requires wider speed output, wider torque output and more reliable performance and more reasonable cost to adapt to more complex and variable working conditions. For the rotary drive of engineering machinery such as cranes, due to the compact space of the rotary platform and other factors, a hydraulic system is often used as a transmission method, that is, power is transmitted to the rotary mechanism by a hydraulic pump, oil pipe, control valve and hydraulic motor to drive the rotary motion. Common rotary motion adopts single-motor drive, double-motor drive or four-motor drive. With the development of large-scale product demand, single-motor drive and double-motor drive can only increase the size of the motor to provide greater torque output, but large-size motors are in conflict with compact spaces. Therefore, in the rotary drive system of large-scale engineering machinery, four-motor drive rotary mechanisms are increasingly valued by the industry, and multi-stage adjustable torque and speed of the rotary mechanism have become the focus and development direction of the industry.

[0003] At present, in order to realize synchronous rotation and speed control, the existing four-motor rotary drive hydraulic control system often adopts multiple proportional valves for control, uses a large number of sensor feedback signals and complex electrical control systems, resulting in high system cost, complex control, high failure rate and difficult maintenance. For example, patent CN108869690A discloses a multi-motor synchronous rotary drive system and a driving method thereof, which uses one pump oil source to four proportional reversing valves, each proportional reversing valve controls one motor drive, and the information of each motor individually set rotary encoder and each motor individually set oil pressure transmitter is fed back to the control module, the control module issues instructions to control the opening of the proportional reversing valve of each motor, thereby realizing the driving and speed synchronization control of four motors. Since the system uses too many proportional controls and too many sensors, it will cause high application cost, and since the system is too complex and has too many electrical control points, it has a high failure rate. Once a proportional reversing valve or a pressure variable sensor or a motor speed code sensor fails, it will cause unstable control, different speed of a motor, and will also hinder the driving force output of other motors, which is easy to cause unstable system operation and high failure rate. SUMMARY

[0004] This invention provides a multi-gear stepless speed-regulating hydraulic system and a rotary drive mechanism for rotary drive, which can provide wide torque output and wide speed output, and can also realize low power consumption standby control and stepless adjustment of motor speed at any gear, and greatly reduce system control complexity, application cost and failure rate.

[0005] According to one aspect of the present invention, a multi-gear continuously variable speed hydraulic system for rotary drive is provided, comprising a main control valve group, a gear switching valve group, a first hydraulic control valve group, a second hydraulic control valve group, and a third hydraulic control valve group. The first hydraulic control valve group is connected to a first motor and a second motor. The second hydraulic control valve group is connected to a second motor and a third motor. The third hydraulic control valve group is connected to a third motor and a fourth motor. The main control valve group is connected to a motor drive pressure oil source and the second hydraulic control valve group, respectively, for controlling the motor's forward and reverse rotation for continuously variable speed regulation or putting the motor in a standby state. The gear switching valve group is connected to a gear switching pressure oil source, the first hydraulic control valve group, the second hydraulic control valve group, and the third hydraulic control valve group, respectively, for controlling the working state of the four motors to achieve switching between low-speed high-torque drive gear, medium-speed medium-torque drive gear, and high-speed low-torque drive gear.

[0006] Furthermore, the main control valve group includes a three-way flow valve, a relief valve, a three-position four-way proportional directional valve, and a shuttle valve. The inlet of the three-position four-way proportional directional valve is connected to the motor drive pressure oil source, the two working ports are connected to the second hydraulic control valve group, and the return port is connected to the oil tank. It is used to control the stepless speed regulation of the motor's forward and reverse rotation or to put the motor in standby mode. The shuttle valve is connected to the two working ports of the three-position four-way proportional directional valve, the three-way flow valve, and the relief valve, respectively. It is used to feed back the maximum working pressure of the system to the three-way flow valve and the relief valve. The three-way flow valve is also connected to the inlet of the three-position four-way proportional directional valve, the relief valve, and the oil tank, respectively. It is used to unload the motor drive pressure oil source and provide pressure compensation for the three-position four-way proportional directional valve when the system is in standby mode.

[0007] Furthermore, when the three-position four-way proportional directional valve is in the neutral position, the motor drive pressure oil source is unloaded through the three-way flow valve, and the motor is in a standby state. When the three-position four-way proportional directional valve is switched to the left position, the motor is driven to rotate forward or reverse, and the speed is infinitely adjustable by controlling the opening of the three-position four-way proportional directional valve. When the three-position four-way proportional directional valve is switched to the right position, the motor is driven to rotate in reverse or forward, and the speed is infinitely adjustable by controlling the opening of the three-position four-way proportional directional valve.

[0008] Furthermore, the gear shifting valve assembly includes a first two-position four-way hydraulic directional valve, a first three-position four-way manual directional valve, and a first two-position three-way hydraulic directional valve. All three valves are connected to the gear shifting pressure oil source and the oil tank. The two working ports of the first two-position four-way hydraulic directional valve are respectively connected to the two control ports of the first hydraulic valve assembly and the two control ports of the third hydraulic valve assembly, for controlling the input of high-pressure control oil to each control port. The first two-position three-way hydraulic directional valve is connected to the control port of the second hydraulic valve group, which is used to control the input of high-pressure or low-pressure control oil at the control port. The first three-position four-way manual directional valve is also connected to the control ports of the first two-position four-way hydraulic directional valve and the first two-position three-way hydraulic directional valve, which is used to control the input oil pressure of each control port, so as to control the working state of the four motors to achieve switching between low-speed high-torque drive gear, medium-speed medium-torque drive gear and high-speed low-torque drive gear.

[0009] Furthermore, the first hydraulic control valve group includes a second two-position three-way hydraulic control directional valve, a first hydraulic control check valve, a first two-way hydraulic control directional valve, and a second two-way hydraulic control directional valve. The control ports of the first hydraulic control check valve, the first two-way hydraulic control directional valve, and the second two-way hydraulic control directional valve are all connected to one working port of the first two-position four-way hydraulic control directional valve. The inlet port of the first hydraulic control check valve is also connected to the other working port of the first two-position four-way hydraulic control directional valve. The outlet port of the first hydraulic control check valve is connected to the control port of the second two-position three-way hydraulic control directional valve. The first two-way hydraulic control directional valve is connected to port B of the first motor and port C of the second motor, respectively. The motor's port B is connected to the second two-position three-way hydraulic directional valve. The second two-way hydraulic directional valve is connected to the first motor's port A, the second motor's port A, and the second two-position three-way hydraulic directional valve, respectively. When high-pressure control oil is input into the control ports of the first and second two-way hydraulic directional valves and low-pressure control oil is input into the control port of the second two-position three-way hydraulic directional valve, the first motor and the second motor are connected in parallel. When low-pressure control oil is input into the control ports of the first and second two-way hydraulic directional valves and high-pressure control oil is input into the control port of the second two-position three-way hydraulic directional valve, the first motor floats.

[0010] Furthermore, the second hydraulic control valve group includes a third two-position three-way hydraulic control directional valve and a fourth two-position three-way hydraulic control directional valve. The third two-position three-way hydraulic control directional valve is connected to the main control valve group, port A of the second motor, and port A of the third motor, respectively. The fourth two-position three-way hydraulic control directional valve is connected to the main control valve group, port B of the second motor, and port B of the third motor, respectively. The control oil ports of both the third and fourth two-position three-way hydraulic control directional valves are connected to the first two-position three-way hydraulic control directional valve. When the first two-position three-way hydraulic control directional valve outputs high-pressure control oil, the second motor and the third motor are connected in series. When the first two-position three-way hydraulic control directional valve outputs low-pressure control oil, the second motor and the third motor are connected in parallel.

[0011] Furthermore, the third hydraulic control valve group includes a fifth two-position three-way hydraulic control directional valve, a second hydraulic control check valve, a third two-way hydraulic control directional valve, and a fourth two-way hydraulic control directional valve. The control ports of the second hydraulic control check valve, the third two-way hydraulic control directional valve, and the fourth two-way hydraulic control directional valve are all connected to one working port of the first two-position four-way hydraulic control directional valve. The inlet port of the second hydraulic control check valve is also connected to the other working port of the first two-position four-way hydraulic control directional valve. The outlet port of the second hydraulic control check valve is connected to the control port of the fifth two-position three-way hydraulic control directional valve. The third two-way hydraulic control directional valve is connected to port B of the third motor and port 4 of the fourth motor. The B port of the motor is connected to the fifth two-position three-way hydraulic directional valve. The fourth two-way hydraulic directional valve is connected to the A port of the third motor, the A port of the fourth motor, and the fifth two-position three-way hydraulic directional valve. When high-pressure control oil is input into the control ports of the third and fourth two-way hydraulic directional valves and low-pressure control oil is input into the control port of the fifth two-position three-way hydraulic directional valve, the third motor and the fourth motor are connected in parallel. When low-pressure control oil is input into the control ports of the third and fourth two-way hydraulic directional valves and high-pressure control oil is input into the control port of the fifth two-position three-way hydraulic directional valve, the fourth motor floats.

[0012] Furthermore, when the first three-position four-way manual directional valve is switched to the left position, the four motors are connected in parallel, and each motor outputs high torque and low speed; when the first three-position four-way manual directional valve is switched to the middle position, the first motor and the fourth motor float, and the second motor and the third motor are connected in parallel, and the second motor and the third motor output medium torque and medium speed; when the first three-position four-way manual directional valve is switched to the right position, the first motor and the fourth motor float, and the second motor and the third motor are connected in series, and the second motor and the third motor output low torque and high speed.

[0013] Furthermore, the main control valve group, the gear switching valve group, the first hydraulic control valve group, the second hydraulic control valve group, and the third hydraulic control valve group each form a separate valve group module.

[0014] In addition, the present invention also provides a rotary drive mechanism, which adopts the multi-speed stepless speed-regulating hydraulic system described above.

[0015] The present invention has the following beneficial effects:

[0016] This invention relates to a multi-gear continuously variable hydraulic system for rotary drives. Through a gear-switching valve group, a first hydraulic control valve group, a second hydraulic control valve group, a third hydraulic control valve group, and four motors, it provides three gear control modes: low-speed high-torque drive, medium-speed medium-torque drive, and high-speed low-torque drive. This allows for wide torque and speed output. Furthermore, the main control valve group enables low-power standby control and stepless motor speed adjustment at any gear, meeting the precise speed control requirements of rotary drive mechanisms. It also automatically enters low-power consumption mode during standby, significantly reducing operating energy costs. Moreover, the multi-position control of the gear-switching valve group allows for series, parallel, or floating connections of the oil circuits for four or two motors, automatically compensating for oil source pressure to achieve synchronous motor drive. This effectively solves the speed synchronization problem caused by different individual oil circuits controlling the motors. Since only the main control valve group performs proportional control, and the other valve groups use hydraulic control valves, complex sensors and control programs are unnecessary, greatly reducing system control complexity, application costs, and failure rates.

[0017] In addition, the rotary drive mechanism of the present invention also has the above-mentioned advantages.

[0018] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of the hydraulic principle of a multi-gear continuously variable hydraulic system for rotary drive according to a preferred embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the hydraulic principle of the main control valve assembly according to a preferred embodiment of this application.

[0022] Figure 3 This is a schematic diagram of the hydraulic principle of the gear shifting valve assembly according to a preferred embodiment of this application.

[0023] Figure 4 This is a schematic diagram of the hydraulic principle of the first hydraulic control valve assembly according to a preferred embodiment of this application.

[0024] Figure 5This is a schematic diagram of the hydraulic principle of the second hydraulic control valve assembly according to a preferred embodiment of this application.

[0025] Figure 6 This is a schematic diagram of the hydraulic principle of the third hydraulic control valve assembly according to a preferred embodiment of this application.

[0026] Figure 7 This is a schematic diagram showing the positional arrangement of the four motors in the rotary drive mechanism of a preferred embodiment of this application.

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Main control valve assembly; 2. Gear shifting valve assembly; 3. First hydraulic control valve assembly; 4. Second hydraulic control valve assembly; 5. Third hydraulic control valve assembly; 6. First motor; 7. Second motor; 8. Third motor; 9. Fourth motor; 11. Three-way flow valve; 12. Relief valve; 13. Three-position four-way proportional directional valve; 14. Shuttle valve; 21. First and second-position four-way hydraulic directional valve; 22. First three-position four-way manual directional valve; 23. First and second... 31. Second two-position three-way hydraulic control directional valve; 32. First hydraulic control check valve; 33. First two-way hydraulic control directional valve; 34. Second two-way hydraulic control directional valve; 41. Third two-position three-way hydraulic control directional valve; 42. Fourth two-position three-way hydraulic control directional valve; 51. Fifth two-position three-way hydraulic control directional valve; 52. Second hydraulic control check valve; 53. Third two-way hydraulic control directional valve; 54. Fourth two-way hydraulic control directional valve. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] Reference Figure 1As shown, a preferred embodiment of this application provides a multi-gear continuously variable hydraulic system for rotary drive, which is used to drive a rotary drive mechanism with four motors. The hydraulic system includes a main control valve group 1, a gear switching valve group 2, a first hydraulic control valve group 3, a second hydraulic control valve group 4, and a third hydraulic control valve group 5. The first hydraulic control valve group 3 is connected to the first motor 6 and the second motor 7, and is used to control the first motor 6 to float or be connected in parallel with the second motor 7. The second hydraulic control valve group 4 is connected to the second motor 7 and the third motor 8, and is used to control the second motor 7 and the third motor 8 to be connected in parallel or in series. The third hydraulic control valve group 5 is connected to the third motor 8 and the fourth motor 9, and is used to control the fourth motor 9 to float or be connected in parallel with the third motor 8. The main control valve group 1 is connected to the motor drive pressure oil source and the second hydraulic control valve group 4 respectively, and is used to control the stepless speed regulation of the motor's forward and reverse rotation or to put the motor in standby mode. The gear switching valve group 2 is connected to the gear switching pressure oil source, the first hydraulic control valve group 3, the second hydraulic control valve group 4 and the third hydraulic control valve group 5 respectively, and is used to control the working state of the four motors. It can realize three switching modes: four motors in parallel, the second motor 7 and the third motor 8 in parallel and the first motor 6 and the fourth motor 9 floating, and the second motor 7 and the third motor 8 in series and the first motor 6 and the fourth motor 9 floating. Thus, it can realize the switching between low speed high torque drive gear, medium speed medium torque drive gear and high speed low torque drive gear, providing wide torque output and wide speed output, and can adapt to various complex working conditions. Specifically, the P port of the main control valve group 1 is connected to the motor drive pressure oil source, the T port is connected to the oil tank, and the A and B ports are respectively connected to the A1 and B1 ports of the second hydraulic control valve group 4. The P1 port of the gear shifting valve group 2 is connected to the gear shifting pressure oil source, the T1 port is connected to the oil tank, the PC port is connected to the PC ports of the first hydraulic control valve group 3 and the third hydraulic control valve group 5, the PM port is connected to the PM ports of the first hydraulic control valve group 3 and the third hydraulic control valve group 5, and the D port is connected to the D port of the second hydraulic control valve group 4. The A1 port of the first hydraulic control valve group 3 is connected to the first motor 6. Port A is connected to the first motor 6, port B1 is connected to the first motor 6, port A2 is connected to the second motor 7, port B2 is connected to the second motor 7, port A2 of the second hydraulic control valve group 4 is connected to the second motor 7, port B2 is connected to the second motor 7, port A3 is connected to the third motor 8, port B3 is connected to the third motor 8, port A2 of the third hydraulic control valve group 5 is connected to the third motor 8, port B2 is connected to the third motor 8, port A1 is connected to the fourth motor 9, and port B1 is connected to the fourth motor 9.

[0031] It is understood that the multi-gear stepless speed-regulating hydraulic system for rotary drive in this embodiment, through the gear switching valve group 2, the first hydraulic control valve group 3, the second hydraulic control valve group 4, the third hydraulic control valve group 5, and four motors, provides three gear control modes: low-speed high-torque drive mode, medium-speed medium-torque drive mode, and high-speed low-torque drive mode. This allows for wide torque and speed output. Furthermore, the main control valve group 1 enables low-power standby control and stepless adjustment of motor speed at any gear, meeting the precise speed control requirements of the rotary drive mechanism. It also allows for automatic low-power consumption during standby, significantly reducing operating energy costs. Moreover, the multi-position control of the gear switching valve group 2 allows for series, parallel, or floating connections of the oil circuits of four or two motors, automatically compensating for oil source imbalances to achieve synchronous motor drive. This effectively solves the speed synchronization problem caused by different individual oil circuits controlling the motors. Furthermore, proportional control is only performed through the main control valve group 1, with the remaining valve groups using hydraulic control valves, eliminating the need for complex sensors and control programs, greatly reducing system control complexity, application costs, and failure rates.

[0032] Understandable, such as Figure 2 As shown, the main control valve group 1 includes a three-way flow valve 11, an overflow valve 12, a three-position four-way proportional directional valve 13, and a shuttle valve 14. The oil inlet a of the three-position four-way proportional directional valve 13 is connected to the motor drive pressure oil source, the two working oil ports b and d are respectively connected to the A1 port and B1 port of the second hydraulic control valve group 4, and the oil return port c is connected to the oil tank. It is used to control the stepless speed regulation of the motor's forward and reverse rotation or to put the motor in standby mode. The shuttle valve 14 is respectively connected to the two working oil ports b and d of the three-position four-way proportional directional valve 13, the three-way flow valve 11, and the overflow valve 12. It is used to feed back the maximum working pressure of the system to the three-way flow valve 11 and the overflow valve 12. The three-way flow valve 11 is also respectively connected to the oil inlet of the three-position four-way proportional directional valve 13, the overflow valve 12, and the oil tank. It is used to unload the motor drive pressure oil source and provide pressure compensation for the three-position four-way proportional directional valve 13 when the system is in standby mode. The three-position four-way proportional directional valve 13 can be a manual valve or an electrically controlled valve, with a manual valve being preferred.

[0033] It is understood that when the three-position four-way proportional directional valve 13 is in the neutral position, the motor drive pressure oil source is unloaded through the three-way flow valve 11, and the motor is in a standby state. When the three-position four-way proportional directional valve 13 is switched to the left position, the motor is driven to rotate forward or reverse, and the speed is infinitely adjustable by controlling the opening of the three-position four-way proportional directional valve 13. When the three-position four-way proportional directional valve 13 is switched to the right position, the motor is driven to rotate in reverse or forward, and the speed is infinitely adjustable by controlling the opening of the three-position four-way proportional directional valve 13.

[0034] In addition, such as Figure 3As shown, the gear shifting valve group 2 includes a first two-position four-way hydraulic directional valve 21, a first three-position four-way manual directional valve 22, and a first two-position three-way hydraulic directional valve 23. All three valves are connected to the gear shifting pressure oil source and the oil tank. The two working ports of the first two-position four-way hydraulic directional valve 21 are connected to the two control ports of the first hydraulic valve group 3 and the two control ports of the third hydraulic valve group 5, respectively, to control the input of each control port. High-pressure control oil or low-pressure control oil is used. One working port of the first two-position three-way hydraulic directional valve 23 is connected to the control port of the second hydraulic valve group 4 to control the input of high-pressure control oil or low-pressure control oil at the control port. The first three-position four-way manual directional valve 22 is also connected to the control ports of the first two-position four-way hydraulic directional valve 21 and the first two-position three-way hydraulic directional valve 23 to control the input oil pressure of each control port, so as to control the working state of the four motors to realize the switching between low-speed high-torque drive gear, medium-speed medium-torque drive gear and high-speed low-torque drive gear.

[0035] In addition, such as Figure 4 As shown, the first hydraulic control valve group 3 includes a second two-position three-way hydraulic control directional valve 31, a first hydraulic control check valve 32, a first two-way hydraulic control directional valve 33, and a second two-way hydraulic control directional valve 34. The control ports of the first hydraulic control check valve 32, the first two-way hydraulic control directional valve 33, and the second two-way hydraulic control directional valve 34 are all connected to one working port of the first two-position four-way hydraulic control directional valve 21. The inlet port of the first hydraulic control check valve 32 is also connected to the other working port of the first two-position four-way hydraulic control directional valve 21. The outlet port of the first hydraulic control check valve 32 is connected to the control port of the second two-position three-way hydraulic control directional valve 31. The first two-way hydraulic control directional valve 33 is connected to port B of the first motor 6, the first two-way three-way hydraulic control directional valve 34, and the second two-way hydraulic control directional valve 34. The B port of the second motor 7 is connected to the second two-position three-way hydraulic directional valve 31. The second two-way hydraulic directional valve 34 is connected to the A port of the first motor 6, the A port of the second motor 7, and the second two-position three-way hydraulic directional valve 31. When high-pressure control oil is input into the control ports of the first two-way hydraulic directional valve 33 and the second two-way hydraulic directional valve 34, and low-pressure control oil is input into the control port of the second two-position three-way hydraulic directional valve 31, the first motor 6 and the second motor 7 are connected in parallel. When low-pressure control oil is input into the control ports of the first two-way hydraulic directional valve 33 and the second two-way hydraulic directional valve 34, and high-pressure control oil is input into the control port of the second two-position three-way hydraulic directional valve 31, the first motor 6 floats.

[0036] In addition, such as Figure 5As shown, the second hydraulic control valve group 4 includes a third two-position three-way hydraulic control directional valve 41 and a fourth two-position three-way hydraulic control directional valve 42. The third two-position three-way hydraulic control directional valve 41 is connected to the main control valve group 1, the A port of the second motor 7, and the A port of the third motor 8, respectively. The fourth two-position three-way hydraulic control directional valve 42 is connected to the main control valve group 1, the B port of the second motor 7, and the B port of the third motor 8, respectively. The control oil ports of the third two-position three-way hydraulic control directional valve 41 and the fourth two-position three-way hydraulic control directional valve 42 are both connected to the first two-position three-way hydraulic control directional valve 23. When the first two-position three-way hydraulic control directional valve 23 outputs high-pressure control oil, the second motor 7 and the third motor 8 are connected in series. When the first two-position three-way hydraulic control directional valve 23 outputs low-pressure control oil, the second motor 7 and the third motor 8 are connected in parallel.

[0037] In addition, such as Figure 6 As shown, the third hydraulic control valve group 5 includes a fifth two-position three-way hydraulic control directional valve 51, a second hydraulic control check valve 52, a third two-way hydraulic control directional valve 53, and a fourth two-way hydraulic control directional valve 54. The control ports of the second hydraulic control check valve 52, the third two-way hydraulic control directional valve 53, and the fourth two-way hydraulic control directional valve 54 are all connected to one working port of the first two-position four-way hydraulic control directional valve 21. The inlet port of the second hydraulic control check valve 52 is also connected to the other working port of the first two-position four-way hydraulic control directional valve 21. The outlet port of the second hydraulic control check valve 52 is connected to the control port of the fifth two-position three-way hydraulic control directional valve 51. The third two-way hydraulic control directional valve 53 is connected to the B port of the third motor 8, the second two-way hydraulic control directional valve 54, and the third two-way hydraulic control directional valve 54. The B port of the four motors 9 is connected to the fifth two-position three-way hydraulic directional valve 51. The fourth two-way hydraulic directional valve 54 is connected to the A port of the third motor 8, the A port of the fourth motor 9, and the fifth two-position three-way hydraulic directional valve 51. When high-pressure control oil is input into the control ports of the third two-way hydraulic directional valve 53 and the fourth two-way hydraulic directional valve 54, and low-pressure control oil is input into the control port of the fifth two-position three-way hydraulic directional valve 51, the third motor 8 and the fourth motor 9 are connected in parallel. When low-pressure control oil is input into the control ports of the third two-way hydraulic directional valve 53 and the fourth two-way hydraulic directional valve 54, and high-pressure control oil is input into the control port of the fifth two-position three-way hydraulic directional valve 51, the fourth motor 9 floats.

[0038] It is understandable that when the first three-position four-way manual directional valve 22 is switched to the left position, the four motors are connected in parallel, and each motor outputs high torque and low speed; when the first three-position four-way manual directional valve 22 is switched to the middle position, the first motor 6 and the fourth motor 9 float, the second motor 7 and the third motor 8 are connected in parallel, and the second motor 7 and the third motor 8 output medium torque and medium speed; when the first three-position four-way manual directional valve 22 is switched to the right position, the first motor 6 and the fourth motor 9 float, the second motor 7 and the third motor 8 are connected in series, and the second motor 7 and the third motor 8 output low torque and high speed.

[0039] It can be understood that the working process of the hydraulic system in this embodiment is as follows:

[0040] First, input motor drive pressure oil to port P of main control valve group 1, and input gear switching pressure oil to port P1 of gear switching valve group 2.

[0041] When the handle of the first three-position four-way manual directional valve 22 is moved to the left position, ports a and d, and ports c and b of the first three-position four-way manual directional valve 22 are connected. At this time, oil source P1 acts on chamber a of the first two-position four-way hydraulic directional valve 21 through the ad passage of the first three-position four-way manual directional valve 22, switching the valve core function of the first two-position four-way hydraulic directional valve 21 to the left position, i.e., ports d and e, and ports b and c of the first two-position four-way hydraulic directional valve 21 are connected. Port T1 of the gear shifting valve group 2 is connected to chamber a of the first two-position three-way hydraulic directional valve 23 through the cb passage of the first three-position four-way manual directional valve 22, keeping the valve core function of the first two-position three-way hydraulic directional valve 23 in the left position, i.e., ports c and b of the first two-position three-way hydraulic directional valve 23 are connected. At this time, the PC port of the gear shifting valve group 2 is connected to the P1 port, the PM port is connected to the T1 port, and the D port is connected to the T1 port, so that the PC port is pressurized, the PM port is not pressurized, and the D port is not pressurized. At this time, the PC port of the first hydraulic control valve group 3 is pressurized and the PM port is not pressurized, the PC port of the third hydraulic control valve group 5 is pressurized and the PM port is not pressurized, and the D port of the second hydraulic control valve group 4 is not pressurized. For the first hydraulic control valve group 3, the pressure at its PC port acts on the a chamber of the first two-way hydraulic control directional valve 33 and the a chamber of the second two-way hydraulic control directional valve 34, causing the valve core of the first two-way hydraulic control directional valve 33 to switch to a connection between ports b and c, and the valve core of the second two-way hydraulic control directional valve 34 to switch to a connection between ports b and c. However, since the PM port of the first hydraulic control valve group 3 is not pressurized, the valve core of the second two-position three-way hydraulic control directional valve 31 remains in spring-side function, that is, ports b, c, and d are not connected to each other. At this time, ports A2 and A1 of the first hydraulic control valve group 3 are connected, and ports B2 and B1 are connected, that is, ports A of the first motor 6 are connected to ports A of the second motor 7, and ports B of the first motor 6 are connected to ports B of the second motor 7, and the first motor 6 and the second motor 7 are connected in parallel. For the third hydraulic control valve group 5, the pressure at its PC port acts on the a chamber of the third two-way hydraulic control directional valve 53 and the a chamber of the fourth two-way hydraulic control directional valve 54, causing the valve core of the third two-way hydraulic control directional valve 53 to switch to a connection between ports b and c, and the valve core of the fourth two-way hydraulic control directional valve 54 to switch to a connection between ports b and c. Since the PM port of the third hydraulic control valve group 5 is not pressurized, the valve core of the fifth two-position three-way hydraulic control directional valve 51 remains in spring-side function, that is, ports b, c, and d are not connected to each other. At this time, ports A2 and A1 of the third hydraulic control valve group 5 are connected, and ports B2 and B1 are connected, that is, ports A of the third motor 8 are connected to ports A of the fourth motor 9, and ports B of the third motor 8 are connected to ports B of the fourth motor 9, and the third motor 8 and the fourth motor 9 are connected in parallel.For the second hydraulic control valve group 4, its D port is depressurized, keeping the valve core of the third two-position three-way hydraulic control directional valve 41 on the spring side, i.e., port b and port c are connected. Similarly, the valve core of the fourth two-position three-way hydraulic control directional valve 42 is also kept on the spring side, i.e., port b and port c are connected. This means that ports A1, A2, and A3 of the second hydraulic control valve group 4 are interconnected, as are ports B1, B2, and B3. This connects the A port of the second motor 7 to the A port of the third motor 8, and the B port of the second motor 7 to the B port of the third motor 8, thus achieving parallel operation between the second motor 7 and the third motor 8. Therefore, when the handle of the first three-position four-way manual directional valve 22 is moved to the left position, the A ports of the four motors are interconnected, and the B ports of the four motors are interconnected, achieving parallel oil circuit operation of the four motors. In this state, each motor outputs high torque and low speed, achieving a low-speed, high-torque drive gear.

[0042] When the handle of the first three-position four-way manual directional valve 22 is moved to the neutral position, the bcd ports of the first three-position four-way manual directional valve 22 are interconnected. At this time, the a chamber of the first two-position four-way hydraulic directional valve 21 is connected to the T1 port of the gear shifting valve group 2, that is, the valve core of the first two-position four-way hydraulic directional valve 21 is kept on the spring side, i.e., the d port is connected to the c port, and the b port is connected to the e port. The a chamber of the first two-position three-way hydraulic directional valve 23 is connected to the T1 port of the gear shifting valve group 2, and the valve core of the first two-position three-way hydraulic directional valve 23 is kept on the spring side, i.e., the b port is connected to the c port. That is, the PC port of the gear shifting valve group 2 is connected to the T1 port, the PM port is connected to the P1 port, and the D port is connected to the T1 port, so that the PC port is depressurized, the PM port is pressurized, and the D port is depressurized. At this time, the PC port of the first hydraulic control valve group 3 is not pressurized while the PM port is pressurized; the PC port of the third hydraulic control valve group 5 is not pressurized while the PM port is pressurized; and the D port of the second hydraulic control valve group 4 is not pressurized. For the first hydraulic control valve group 3, since its PC port is not pressurized, the valve core of the first two-way hydraulic control directional valve 33 remains in spring-side function, i.e., ports b and c are not connected. The valve core of the second two-way hydraulic control directional valve 34 remains in spring-side function, and ports b and c are not connected. Since the PM port of the first hydraulic control valve group 3 is pressurized, the pressure oil acts on the a chamber of the second two-position three-way hydraulic control directional valve 31 through the ba passage of the first hydraulic control check valve 32, causing the valve core function of the second two-position three-way hydraulic control directional valve 31 to switch to port bcd interconnected. At this time, ports A1 and B1 of the first hydraulic control valve group 3 are connected, ports A1 and A2 are not connected, and ports B1 and B2 are not connected, i.e., the first motor 6 floats. For the third hydraulic control valve group 5, since its PC port is not pressurized, the valve core of the third two-way hydraulic control directional valve 53 remains in spring-side function, i.e., ports b and c are not connected. The valve core of the fourth two-way hydraulic control directional valve 54 remains in spring-side function, and ports b and c are not connected. Since the PM port of the third hydraulic control valve group 5 is pressurized, the pressure oil acts on the a chamber of the fifth two-position three-way hydraulic control directional valve 51 through the ba passage of the second hydraulic control check valve 52, causing the valve core function of the fifth two-position three-way hydraulic control directional valve 51 to switch to port bcd being connected to each other. At this time, ports A1 and B1 of the third hydraulic control valve group 5 are connected, ports A1 and A2 are not connected, and ports B1 and B2 are not connected, i.e., the fourth motor 9 floats. For the second hydraulic control valve group 4, since its D port is not pressurized, the valve core of the third two-position three-way hydraulic control directional valve 41 is kept on the spring side, that is, the b port is connected to the c port. The valve core of the fourth two-position three-way hydraulic control directional valve 42 is kept on the spring side, that is, the b port is connected to the c port. That is, the A1 port, A2 port, and A3 port of the second hydraulic control valve group 4 are connected to each other, and the B1 port, B2 port, and B3 port are connected to each other. Thus, the A port of the second motor 7 is connected to the A port of the third motor 8, and the B port of the second motor 7 is connected to the B port of the third motor 8. The second motor 7 and the third motor 8 are connected in parallel.In summary, when the handle of the first three-position four-way manual directional valve 22 is moved to the neutral position, the first motor 6 and the fourth motor 9 float, and the second motor 7 and the third motor 8 form a parallel oil circuit. In this state, the motor output torque is 1 / 2 times that of the above-mentioned "low speed high torque drive gear", and the output speed is twice that of the above-mentioned "low speed high torque drive gear", thus realizing the medium speed medium torque drive gear.

[0043] When the handle of the first three-position four-way manual directional valve 22 is moved to the right position, that is, port a and port b of the first three-position four-way manual directional valve 22 are connected, and port c and port d are connected. At this time, the a chamber of the first two-position four-way hydraulic directional valve 21 is connected to the T1 port of the gear shifting valve group 2, and the valve core of the first two-position four-way hydraulic directional valve 21 remains on the spring side, that is, port d and port c are connected, and port b and port e are connected. The a chamber of the first two-position three-way hydraulic directional valve 23 is connected to the P1 port of the gear shifting valve group 2, and the valve core of the first two-position three-way hydraulic directional valve 23 switches to the position where port c and port d are connected. This makes the PC port of the gear shifting valve group 2 connected to the T1 port, the PM port connected to the P1 port, and the D port connected to the P1 port, that is, the PC port is depressurized, the PM port is pressurized, and the D port is pressurized. At this time, the PC port of the first hydraulic control valve group 3 is not pressurized while the PM port is pressurized; the PC port of the third hydraulic control valve group 5 is not pressurized while the PM port is pressurized; and the D port of the second hydraulic control valve group 4 is pressurized. For the first hydraulic control valve group 3, since its PC port is not pressurized, the valve core of the first two-way hydraulic control directional valve 33 remains in spring-side function, i.e., ports b and c are not connected. The valve core of the second two-way hydraulic control directional valve 34 remains in spring-side function, and ports b and c are not connected. Because the PM port of the first hydraulic control valve group 3 is pressurized, the pressure oil acts on the a chamber of the second two-position three-way hydraulic control directional valve 31 through the ba passage of the first hydraulic control check valve 32, causing the valve core function of the second two-position three-way hydraulic control directional valve 31 to switch to port bcd interconnected. At this time, ports A1 and B1 of the first hydraulic control valve group 3 are connected, ports A1 and A2 are not connected, and ports B1 and B2 are not connected, i.e., the first motor 6 floats. For the third hydraulic control valve group 5, since its PC port is not pressurized, the valve core of the third two-way hydraulic control directional valve 53 remains in spring-side function, i.e., ports b and c are not connected. The valve core of the fourth two-way hydraulic control directional valve 54 remains in spring-side function, and ports b and c are not connected. Since the PM port of the third hydraulic control valve group 5 is pressurized, the pressure oil acts on the a chamber of the fifth two-position three-way hydraulic control directional valve 51 through the ba passage of the second hydraulic control check valve 52, causing the valve core function of the fifth two-position three-way hydraulic control directional valve 51 to switch to port bcd being connected to each other. At this time, ports A1 and B1 of the third hydraulic control valve group 5 are connected, ports A1 and A2 are not connected, and ports B1 and B2 are not connected, i.e., the fourth motor 9 floats. For the fourth hydraulic control valve group 4, since its D port is pressurized, the valve core function of the third two-position three-way hydraulic control directional valve 41 is switched to connect the c port and the d port, and the valve core function of the fourth two-position three-way hydraulic control directional valve 42 is switched to connect the c port and the d port. That is, the A1 port and the A3 port of the second hydraulic control valve group 4 are connected, the B3 port and the A2 port are connected, and the B2 port and the B1 port are connected. This realizes that the A port of the second motor 7 is connected to the B port of the third motor 8, and the B port of the second motor 7 is connected to the B1 port of the second hydraulic control valve group 4. The A port of the third motor 8 is connected to the A1 port of the second hydraulic control valve group 4, and the second motor 7 and the third motor 8 are connected in series.In summary, when the handle of the first three-position four-way manual directional valve 22 is moved to the right position, the first motor 6 and the fourth motor 9 float, and the second motor 7 and the third motor 8 form a series oil circuit. In this state, the motor output torque is 1 / 4 times that of the above-mentioned "low speed high torque drive gear", and the output speed is 4 times that of the above-mentioned "low speed high torque drive gear", thus realizing the high speed low torque drive gear.

[0044] Furthermore, in any of the aforementioned low-speed high-torque drive gears, medium-speed medium-torque drive gears, and high-speed low-torque drive gears, motor drive oil is input to the P port of the main control valve group 1. The A port of the main control valve group 1 is connected to the A1 port of the second hydraulic control valve group 4, and the B port of the main control valve group 1 is connected to the B1 port of the second hydraulic control valve group 4. That is, the main control valve group 1 is connected to the motor in any of the aforementioned low-speed high-torque drive gears, medium-speed medium-torque drive gears, and high-speed low-torque drive gears to form the main motor drive circuit. When the handle of the three-position four-way proportional directional valve 13 is moved to the neutral position, i.e., ports A, B, and D are connected, the pressure at ports A and B of the main control valve group 1 is the same, meaning the pressure acting on both sides of the motor circuit is the same, thus putting the motor in a standby, non-rotating state. The shuttle valve 14 feeds back the pressure from ports A and B of the main control valve group 1 to chamber d of the three-way flow valve 11. Since the pressure in chamber d of the three-way flow valve 11 is the same as in chamber a in this state, the valve core of the three-way flow valve 11 remains in the spring position. On the side, port c is connected to port b. The motor drive oil source input from port P of the main control valve group 1 flows directly back to the oil tank through the cb passage of the three-way flow valve 11, realizing pressure unloading of the main drive circuit of the motor. At this time, the pressure of the main drive system is kept at the minimum value due to oil source unloading. According to the formula Pi (power) = P (pressure difference) × Q (flow rate) / 60 × η, where η is the total pump efficiency, which is a constant, it is derived that the power consumption of the main drive system is the lowest in the standby state, that is, the low power consumption standby function is realized.

[0045] When the handle of the three-position four-way proportional directional valve 13 is moved to a certain opening degree on the left, connecting port a and port d, and port b and port c, the oil input from port P of the main control valve group 1 passes through the ad passage of the three-position four-way proportional directional valve 13 to port B of the main control valve group 1, and then to port B1 of the second hydraulic control valve group 4. This drives the motor circuit in any of the following gear positions: low-speed high-torque drive, medium-speed medium-torque drive, and high-speed low-torque drive, causing the motor to rotate clockwise (or counterclockwise). When rotated, the shuttle valve 14 feeds back the higher pressure of port B of the main control valve group 1 to the d chamber of the three-way flow valve 11. Let the pressure in the d chamber of the three-way flow valve 11 be Pd, and the spring force in the d chamber of the three-way flow valve 11 initially be Pt (constant). The pressure in the a chamber of the three-way flow valve 11 is Pa. According to the valve core balance relationship of the three-way flow valve 11, Pa = Pd + Pt. That is, the pressure difference before and after the three-position four-way proportional directional valve 13 is ΔP = Pa - Pd = Pt, that is, ΔP is constant. According to Bernoulli's theorem, the flow rate Q through the three-position four-way proportional directional valve 13 is Q = ΔP*S / n, where n is the resistance coefficient, which is constant, and S is the cross-sectional area of ​​the hydraulic oil flowing through the three-position four-way proportional directional valve 13. That is, the flow rate through the three-position four-way proportional directional valve 13 is only related to S, that is, only related to the valve core opening, and is not affected by the load pressure. This enables the three-way flow valve 11 to perform the pressure compensation function for the three-position four-way proportional directional valve 13. By moving the handle of the three-position four-way proportional directional valve 13 to change the valve core opening, the proportional control of the flow rate output from port B of the main control valve group 1 is realized. This enables stepless speed regulation of the motor rotating clockwise (or counterclockwise) in any of the above-mentioned low-speed high-torque drive gear, medium-speed medium-torque drive gear, and high-speed low-torque drive gear.

[0046] When the handle of the three-position four-way proportional directional valve 13 is moved to a certain opening degree on the right, connecting ports a and b, and ports c and d, the oil input from port P of the main control valve group 1 flows through the ab passage of the three-position four-way proportional directional valve 13 to port A of the main control valve group 1, and then to port A1 of the second hydraulic control valve group 4. This drives the motor circuit in any of the following gears: low-speed high-torque drive, medium-speed medium-torque drive, and high-speed low-torque drive, causing the motor to rotate counterclockwise (or clockwise). Similarly, by changing the valve core opening degree by moving the handle of the three-position four-way proportional directional valve 13, proportional control of the flow rate output from port A of the main control valve group 1 is achieved, enabling stepless speed regulation of the motor rotating counterclockwise (or clockwise) in any of the following gears: low-speed high-torque drive, medium-speed medium-torque drive, and high-speed low-torque drive.

[0047] Optionally, the main control valve group 1, the gear switching valve group 2, the first hydraulic control valve group 3, the second hydraulic control valve group 4, and the third hydraulic control valve group 5 are each formed as separate valve group modules, which is beneficial to achieve flexible spatial layout.

[0048] In addition, another embodiment of the present invention provides a rotary drive mechanism, preferably employing the multi-speed stepless speed-regulating hydraulic system described above. Figure 7 As shown, in the rotary drive mechanism, the first motor 6 and the fourth motor 9 are diagonally distributed, and the second motor 7 and the third motor 8 are diagonally distributed, so as to achieve a reasonable and uniform distribution of motor output torque on the actuator and effectively reduce stress concentration in the rotary drive mechanism.

[0049] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0050] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-gear stepless speed regulation hydraulic system for rotary drive, characterized in that, The main control valve group (1), gear shift valve group (2), first hydraulic control valve group (3), second hydraulic control valve group (4) and third hydraulic control valve group (5) are included, the first hydraulic control valve group (3) is connected with the first motor (6) and the second motor (7), the second hydraulic control valve group (4) is connected with the second motor (7) and the third motor (8), the third hydraulic control valve group (5) is connected with the third motor (8) and the fourth motor (9), the main control valve group (1) is connected with the motor drive pressure oil source and the second hydraulic control valve group (4) respectively, for controlling the motor positive rotation and reverse rotation stepless speed regulation or making the motor in standby state, the gear shift valve group (2) is connected with gear shift pressure oil source, first hydraulic control valve group (3), second hydraulic control valve group (4) and third hydraulic control valve group (5) respectively, for controlling the working state of four motors to realize the switching between low speed high torque drive gear, medium speed medium torque drive gear and high speed low torque drive gear; The main control valve group (1) includes three-way flow valve (11), overflow valve (12), three-position four-way proportional directional valve (13) and shuttle valve (14), the oil inlet of three-position four-way proportional directional valve (13) is connected with the motor drive pressure oil source, two working oil ports are connected with the second hydraulic control valve group (4), and the oil return port is connected with the oil tank, for controlling the motor positive rotation and reverse rotation stepless speed regulation or making the motor in standby state, the shuttle valve (14) is connected with two working oil ports of three-position four-way proportional directional valve (13), three-way flow valve (11) and overflow valve (12) respectively, for feeding the maximum working pressure of system to three-way flow valve (11) and overflow valve (12), three-way flow valve (11) is also connected with the oil inlet of three-position four-way proportional directional valve (13), overflow valve (12) and oil tank respectively, for realizing the unloading of motor drive pressure oil source and the pressure compensation of three-position four-way proportional directional valve (13) when the system is in standby state. The gear shift valve group (2) comprises a first two-position four-way hydraulic control reversing valve (21), a first three-position four-way manual reversing valve (22) and a first two-position three-way hydraulic control reversing valve (23), all of which are connected with a gear shift pressure oil source and an oil tank, two working oil ports of the first two-position four-way hydraulic control reversing valve (21) are respectively connected with two control oil ports of the first hydraulic control valve group (3) and two control oil ports of the third hydraulic control valve group (5), for controlling the input of high-pressure control oil or low-pressure control oil in each control oil port, one working oil port of the first two-position three-way hydraulic control reversing valve (23) is connected with a control oil port of the second hydraulic control valve group (4), for controlling the input of high-pressure control oil or low-pressure control oil in the control oil port, the first three-position four-way manual reversing valve (22) is also connected with control oil ports of the first two-position four-way hydraulic control reversing valve (21) and the first two-position three-way hydraulic control reversing valve (23), for controlling the input oil pressure of each control oil port, so as to control the working state of the four motors to realize the switching among the low-speed high-torque drive gear, the medium-speed medium-torque drive gear and the high-speed low-torque drive gear.

2. The multi-stage stepless speed regulation hydraulic system for rotary drive according to claim 1, characterized in that, When the three-position four-way proportional reversing valve (13) is in the middle position, the motor drive pressure oil source is unloaded through the three-way flow valve (11), and the motor is in the standby non-rotation state; when the three-position four-way proportional reversing valve (13) is switched to the left position, the drive motor rotates forward or reverses, and the rotational speed is infinitely adjusted by controlling the opening of the three-position four-way proportional reversing valve (13); when the three-position four-way proportional reversing valve (13) is switched to the right position, the drive motor reverses or rotates forward, and the rotational speed is infinitely adjusted by controlling the opening of the three-position four-way proportional reversing valve (13).

3. The multi-stage stepless speed regulation hydraulic system for rotary drive according to claim 1, characterized in that, The first hydraulic control valve group (3) comprises a second two-position three-way hydraulic control reversing valve (31), a first hydraulic control check valve (32), a first two-way hydraulic control reversing valve (33) and a second two-way hydraulic control reversing valve (34), control oil ports of the first hydraulic control check valve (32), the first two-way hydraulic control reversing valve (33) and the second two-way hydraulic control reversing valve (34) are connected with one working oil port of the first two-position four-way hydraulic control reversing valve (21), an oil inlet of the first hydraulic control check valve (32) is also connected with another working oil port of the first two-position four-way hydraulic control reversing valve (21), an oil outlet of the first hydraulic control check valve (32) is connected with a control oil port of the second two-position three-way hydraulic control reversing valve (31), the first two-way hydraulic control reversing valve (33) is connected with a B port of the first motor (6), a B port of the second motor (7) and the second two-position three-way hydraulic control reversing valve (31) respectively, the second two-way hydraulic control reversing valve (34) is connected with an A port of the first motor (6), an A port of the second motor (7) and the second two-position three-way hydraulic control reversing valve (31) respectively, when control oil ports of the first two-way hydraulic control reversing valve (33) and the second two-way hydraulic control reversing valve (34) input high-pressure control oil and the control oil port of the second two-position three-way hydraulic control reversing valve (31) inputs low-pressure control oil, the first motor (6) and the second motor (7) are connected in parallel, when the control oil ports of the first two-way hydraulic control reversing valve (33) and the second two-way hydraulic control reversing valve (34) input low-pressure control oil and the control oil port of the second two-position three-way hydraulic control reversing valve (31) inputs high-pressure control oil, the first motor (6) is floating.

4. The multi-stage stepless speed regulation hydraulic system for rotary drive according to claim 3, characterized in that, The second hydraulic control valve group (4) comprises a third two-position three-way hydraulic control reversing valve (41) and a fourth two-position three-way hydraulic control reversing valve (42), the third two-position three-way hydraulic control reversing valve (41) is connected with the master control valve group (1), an A port of the second motor (7) and an A port of the third motor (8) respectively, the fourth two-position three-way hydraulic control reversing valve (42) is connected with the master control valve group (1), a B port of the second motor (7) and a B port of the third motor (8) respectively, control oil ports of the third two-position three-way hydraulic control reversing valve (41) and the fourth two-position three-way hydraulic control reversing valve (42) are connected with the first two-position three-way hydraulic control reversing valve (23), when the first two-position three-way hydraulic control reversing valve (23) outputs high-pressure control oil, the second motor (7) and the third motor (8) are connected in series, when the first two-position three-way hydraulic control reversing valve (23) outputs low-pressure control oil, the second motor (7) and the third motor (8) are connected in parallel.

5. The multi-stage stepless speed regulation hydraulic system for rotary drive according to claim 4, characterized in that, The third hydraulic control valve group (5) comprises a fifth two-position three-way hydraulic control reversing valve (51), a second hydraulic control check valve (52), a third two-way hydraulic control reversing valve (53) and a fourth two-way hydraulic control reversing valve (54), the control oil ports of the second hydraulic control check valve (52), the third two-way hydraulic control reversing valve (53) and the fourth two-way hydraulic control reversing valve (54) are connected with one working oil port of the first two-position four-way hydraulic control reversing valve (21), the oil inlet of the second hydraulic control check valve (52) is also connected with another working oil port of the first two-position four-way hydraulic control reversing valve (21), the oil outlet of the second hydraulic control check valve (52) is connected with the control oil port of the fifth two-position three-way hydraulic control reversing valve (51), the third two-way hydraulic control reversing valve (53) is connected with the B port of the third motor (8), the B port of the fourth motor (9) and the fifth two-position three-way hydraulic control reversing valve (51) respectively, the fourth two-way hydraulic control reversing valve (54) is connected with the A port of the third motor (8), the A port of the fourth motor (9) and the fifth two-position three-way hydraulic control reversing valve (51) respectively, when the control oil ports of the third two-way hydraulic control reversing valve (53) and the fourth two-way hydraulic control reversing valve (54) input high-pressure control oil and the control oil port of the fifth two-position three-way hydraulic control reversing valve (51) inputs low-pressure control oil, the third motor (8) and the fourth motor (9) are connected in parallel, when the control oil ports of the third two-way hydraulic control reversing valve (53) and the fourth two-way hydraulic control reversing valve (54) input low-pressure control oil and the control oil port of the fifth two-position three-way hydraulic control reversing valve (51) inputs high-pressure control oil, the fourth motor (9) is floating.

6. The multi-stage stepless speed regulation hydraulic system for rotary drive according to claim 5, characterized in that, When the first three-position four-way manual reversing valve (22) is switched to the left position, the four motors are connected in parallel, each motor outputs high torque and low speed; when the first three-position four-way manual reversing valve (22) is switched to the middle position, the first motor (6) and the fourth motor (9) are floating, the second motor (7) and the third motor (8) are connected in parallel, the second motor (7) and the third motor (8) output medium torque and medium speed; when the first three-position four-way manual reversing valve (22) is switched to the right position, the first motor (6) and the fourth motor (9) are floating, the second motor (7) and the third motor (8) are connected in series, the second motor (7) and the third motor (8) output low torque and high speed.

7. The multi-stage stepless speed regulating hydraulic system for rotary drive according to claim 1, characterized in that, The master control valve group (1), the gear switching valve group (2), the first hydraulic control valve group (3), the second hydraulic control valve group (4) and the third hydraulic control valve group (5) are separately formed into valve group modules.

8. A swivel drive mechanism characterized by, The multi-gear stepless speed regulation hydraulic system according to any one of claims 1-7 is adopted. The multi-gear stepless speed regulation hydraulic system according to any one of claims 1-7 is adopted.

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