Valve group and hydraulic control system for multiple hydraulic motor torque switching

Abstract

A valve assembly and hydraulic control system for switching the torque of multiple hydraulic motors includes a valve block, which houses a first hydraulically controlled directional valve and a second hydraulically controlled directional valve. The valve block has a working port A, a working port B, and ports A1 and B1, A2 and B2, A3 and B3, and A4 and B4 for connecting four hydraulic motors. Port B of the first hydraulically controlled directional valve, and ports B, B1, and B3 of the second hydraulically controlled directional valve are all connected to working port B. Port A of the first hydraulically controlled directional valve, and ports A, A2, and A4 of the second hydraulically controlled directional valve are all connected to working port A. Port P of the first hydraulically controlled directional valve is connected to port A1, and port T of the first hydraulically controlled directional valve is connected to port B2. Port P of the second hydraulically controlled directional valve is connected to port A3, and port T of the second hydraulically controlled directional valve is connected to port B4. This valve assembly and the hydraulic control system using it can achieve rapid control of torque switching of multiple hydraulic motors, meeting the torque and speed requirements of different working conditions.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic technology, specifically relating to a valve group and hydraulic control system for switching the torque of multiple hydraulic motors. Background Technology

[0002] Workover rigs are the most basic and essential power source for well workover and downhole operations. When working over wells, the rig is required to switch between high and low speeds and high and low torque according to the working conditions.

[0003] Existing drilling and workover rigs typically use hydraulic rotary tables with two or four hydraulic motors. Each motor has a clutch at its front end, which connects the hydraulic motor to the rotary table. When all four hydraulic motors operate simultaneously, the rotary table can output drill pipe at low speed and high torque. When only two hydraulic motors are operating, the clutches must be operated to disengage two of the motors from the rotary table. By controlling the hydraulic circuits of the disengaged two motors through the rotary table's hydraulic circuits, the rotary table can output drill pipe at high speed and low torque.

[0004] The following disadvantages exist in this method of using a clutch to switch torque: (1) The configuration of a clutch leads to a complex mechanical structure, the clutch structure requires a large installation space and many parts, and the synchronous control of multiple clutches is difficult. Moreover, due to the complexity of the mechanical structure, the failure rate is high and the maintenance cost increases; (2) There is a certain lag in switching torque by using the engagement and disengagement of the clutch, and there is a possibility of a brief interruption of power during the switching process. It is not suitable for scenarios that require continuous and stable torque. Utility Model Content

[0005] The purpose of this invention is to provide a valve group and hydraulic control system for switching the torque of multiple hydraulic motors. By designing the oil circuit inside the valve group, rapid control of the torque switching of multiple hydraulic motors can be achieved, meeting the torque and speed requirements of different working conditions.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a valve group for switching the torque of multiple hydraulic motors, including a valve block, wherein a first hydraulically controlled directional valve and a second hydraulically controlled directional valve are provided in the valve block; the valve block is provided with a working oil port A, a working oil port B, and a connecting oil port for connecting four hydraulic motors, wherein the connecting oil ports for connecting the first hydraulic motor are A1 and B1, the connecting oil ports for connecting the second hydraulic motor are A2 and B2, the connecting oil ports for connecting the third hydraulic motor are A3 and B3, and the connecting oil ports for connecting the fourth hydraulic motor are A4 and B4;

[0007] The first and second hydraulically controlled directional valves are three-position four-way valves. Port B of the first and second hydraulically controlled directional valves, as well as ports B1 and B3, are all connected to the working oil port B. Ports A of the first and second hydraulically controlled directional valves, as well as ports A2 and A4, are all connected to the working oil port A. Port P of the first hydraulically controlled directional valve is connected to port A1, and port T of the first hydraulically controlled directional valve is connected to port B2. Port P of the second hydraulically controlled directional valve is connected to port A3, and port T of the second hydraulically controlled directional valve is connected to port B4.

[0008] The first hydraulic directional valve and the second hydraulic directional valve are also connected to the control oil circuit inside the valve block, and the control oil circuit opens at the control oil port on the surface of the valve block.

[0009] Furthermore, the four hydraulic motors are bidirectional motors, and the valve block is also provided with four oil ports, which are respectively used to connect the drain ports of the four hydraulic motors. The four oil ports are connected to the drain port T0 on the surface of the valve block through the drain oil passage inside the valve block.

[0010] Furthermore, the valve block is also equipped with a first overflow valve and a second overflow valve. The inlet of the first overflow valve is connected to the oil line between the working oil port B and the ports B1 and B3. The inlet of the second overflow valve is connected to the oil line between the working oil port A and the ports A2 and A4. The outlets of the first overflow valve and the second overflow valve are connected to the return oil port T on the valve block through the overflow oil line.

[0011] The valve block is also equipped with a first check valve and a second check valve. The inlet of the first check valve is connected to the overflow oil line, and the outlet of the first check valve is connected to the oil line between the working oil port B and the ports B1 and B3. The inlet of the second check valve is connected to the overflow oil line, and the outlet of the second check valve is connected to the oil line between the working oil port A and the ports A2 and A4.

[0012] Furthermore, the drain port T0 is connected to the overflow oil circuit through an oil circuit equipped with a fifth check valve to prevent hydraulic oil in the overflow oil circuit from entering the drain port T0.

[0013] Furthermore, the valve block is provided with a pressure testing port M1 for monitoring the oil pressure at the inlet of the hydraulic motor. The pressure testing port M1 is connected to the working port B through a third check valve and to the working port A through a fourth check valve.

[0014] Furthermore, the valve block is provided with a pressure testing port M2 for monitoring the oil pressure at the inlet of the hydraulic motor. The pressure testing port M2 is connected to the pressure testing port M1 through the oil passage inside the valve block.

[0015] Furthermore, there are two control ports, namely a first control port X1 and a second control port X2. The control ports at both ends of the first hydraulic directional valve are connected to the first control port X1 and the second control port X2, respectively. The control ports at both ends of the second hydraulic directional valve are connected to the first control port X1 and the second control port X2, respectively.

[0016] This utility model also proposes a hydraulic control system for switching the torque of multiple hydraulic motors, including the valve group described above, multiple solenoid directional valves, a hydraulic pump, and an oil tank. The multiple solenoid directional valves include a first solenoid ball valve, a second solenoid ball valve, and a three-position four-way solenoid directional valve. The P port of the three-position four-way solenoid directional valve, the P port of the first solenoid ball valve, and the P port of the second solenoid ball valve are all connected to the outlet of the hydraulic pump. The T port of the three-position four-way solenoid directional valve, the T port of the first solenoid ball valve, and the T port of the second solenoid ball valve are all connected to the oil tank. The A port and B port of the three-position four-way solenoid directional valve are respectively connected to the working oil port A and the working oil port B on the valve block. The A port of the first solenoid ball valve and the A port of the second solenoid ball valve are respectively connected to the first control oil port X1 and the second control oil port X2.

[0017] The beneficial effects of this utility model are: 1. By setting two hydraulic control directional valves in the valve group, each hydraulic control directional valve controls two hydraulic motors, thereby realizing the switching of the series and parallel connection of four hydraulic motors, realizing the output control of the hydraulic rotary drill rod at high speed and low torque and low speed and high torque. Compared with the clutch method, the control is simpler, the switching efficiency is higher, and the torque and speed requirements of different working conditions are met.

[0018] 2. The valve group of this utility model is designed with a balance valve structure consisting of an overflow valve and a check valve. In accordance with the requirement of bidirectional rotation of the hydraulic motor, it is set as a bidirectional balance valve structure, which effectively reduces the equipment failure rate caused by the jamming of the actuator.

[0019] 3. In the valve group of this utility model, the pressure measuring port M1 or M2 is connected to different working ports on the valve block through the third and fourth check valves respectively. In this way, the oil pressure at the inlet end when the hydraulic motor rotates forward can be monitored through a single pressure measuring port M1 or M2, and the oil pressure at the inlet end when the hydraulic motor rotates in reverse can also be monitored.

[0020] 4. The hydraulic control system of this utility model adopts a three-position four-way solenoid directional valve, which can realize the forward and reverse rotation control of the hydraulic motor, and has a wider range of applications. Attached Figure Description

[0021] Figure 1 This is a hydraulic schematic diagram of a valve assembly used for torque switching of multiple hydraulic motors in this utility model.

[0022] Figure 2This is a hydraulic schematic diagram of the hydraulic control system in this utility model;

[0023] The following are the markings in the diagram: 1.1 First hydraulic directional valve, 1.2 Second hydraulic directional valve, 2.1 First relief valve, 2.2 Second relief valve, 3.1 First check valve, 3.2 Second check valve, 3.3 Third check valve, 3.4 Fourth check valve, 3.5 Fifth check valve;

[0024] 1. Hydraulic pump; 21. First solenoid ball valve; 22. Second solenoid ball valve; 3. Three-position four-way solenoid directional valve; 4. Valve assembly; 51. First hydraulic motor; 52. Second hydraulic motor; 53. Third hydraulic motor; 54. Fourth hydraulic motor. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention in any way.

[0026] Example 1

[0027] See attached document Figure 1 As shown, a valve assembly for switching the torque of multiple hydraulic motors includes a valve block, which is provided with a working port A, a working port B, a return port T, a pressure testing port M1, a spare pressure testing port MA, a spare pressure testing port MB, a first hydraulic control port X1, a second hydraulic control port X2, a drain port T0, a drain pressure testing port MT, and a connection port for connecting the hydraulic motors.

[0028] The valve group described in this embodiment controls four hydraulic motors, which can be referred to as follows: Figure 2 As shown, the connection ports for connecting the first hydraulic motor 51 are A1 and B1, the connection ports for connecting the second hydraulic motor 52 are A2 and B2, the connection ports for connecting the third hydraulic motor 53 are A3 and B3, and the connection ports for connecting the fourth hydraulic motor 54 are A4 and B4.

[0029] The valve block also includes a first hydraulically controlled directional valve 1.1 and a second hydraulically controlled directional valve 1.2 in its oil circuit. Both the first hydraulically controlled directional valve 1.1 and the second hydraulically controlled directional valve 1.2 are three-position four-way valves, with working ports including P, T, A, and B. The two ends of the first hydraulically controlled directional valve 1.1 and the second hydraulically controlled directional valve 1.2 are connected to the first control port X1 via a control oil circuit to achieve directional switching.

[0030] The valve block connects all oil ports and valves via oil circuits to achieve series-parallel switching control of four hydraulic motors. The oil circuits within the valve block are configured as follows: Port B of the first hydraulic directional valve 1.1, Port B of the second hydraulic directional valve 1.2, and ports B1 and B3 are all connected to the working oil port B; Port A of the first hydraulic directional valve 1.1, Port A of the second hydraulic directional valve 1.2, and ports A2 and A4 are all connected to the working oil port A; Port P of the first hydraulic directional valve 1.1 is connected to port A1, and Port T of the first hydraulic directional valve 1.1 is connected to port B2; Port P of the second hydraulic directional valve 1.2 is connected to port A3, and Port T of the second hydraulic directional valve 1.2 is connected to port B4.

[0031] The switching process of the valve group of the present invention for the series-parallel connection of four hydraulic motors is as follows: (1) The first hydraulic control directional valve 1.1 and the second hydraulic control directional valve 1.2 are in the following state: Figure 1 In the normal position shown, among the four hydraulic motors connected to the valve group, the first hydraulic motor 51 and the second hydraulic motor 52 are connected in series, and the third hydraulic motor 53 and the fourth hydraulic motor 54 are connected in series. At the same time, the series circuit formed by the first hydraulic motor 51 and the second hydraulic motor 52 is connected in parallel with the series circuit formed by the third hydraulic motor 53 and the fourth hydraulic motor 54, which can jointly drive the hydraulic rotary table drill pipe of the workover rig to rotate. At this time, when the hydraulic oil enters the valve group through the working port B on the valve block, the hydraulic oil is divided into two paths. One path enters the first hydraulic motor 51 through port B1, then enters the second hydraulic motor 52 through port A1 and the P and T ports of the first hydraulic directional valve 1.1 through port B2, and finally enters the valve group again through port A2, and then flows out of the valve group from the working port A and returns to the oil tank. The other path of hydraulic oil enters the third hydraulic motor 53 through port B3, then enters the fourth hydraulic motor 54 through port B4 through port A3 and the P and T ports of the second hydraulic directional valve 1.2, and finally enters the valve group again through port A4, and then flows out of the valve group from the working port A and returns to the oil tank.

[0032] Under this operating condition, the two hydraulic motors connected in series have a large system flow rate. When the two hydraulic motors connected in series are connected in parallel with two other hydraulic motors connected in series, the output torque is the sum of the output torques of the two sets of hydraulic motors when the pressure is constant, which can realize the high-speed, low-torque output of the hydraulic rotary drill rod.

[0033] (2) After the first hydraulic control directional valve 1.1 and the second hydraulic control directional valve 1.2 are switched through the first control port X1, they are in the right position. At this time, the four hydraulic motors connected to the valve group are connected in parallel, and the four hydraulic motors drive the hydraulic rotary table drill rod of the workover machine to rotate. At this time, when the hydraulic oil enters the valve group through the working port B on the valve block, the hydraulic oil is divided into four paths: the first path enters the connected first hydraulic motor 51 through port B1, returns to the valve group through port A1, then flows out of the valve group through the P and A ports of the first hydraulic directional valve 1.1 and returns to the oil tank through the working port A; the second path enters the connected second hydraulic motor 52 through port B2 through the B and T ports of the first hydraulic directional valve 1.1, returns to the valve group through port A2, and flows out of the valve group through the working port A and returns to the oil tank; the third path enters the connected third hydraulic motor 53 through port B3, returns to the valve group through port A3, then flows out of the valve group through the P and A ports of the second hydraulic directional valve 1.2 and returns to the oil tank through the working port A; the fourth path enters the connected fourth hydraulic motor 54 through port B4 through the B and T ports of the second hydraulic directional valve 1.2, returns to the valve group through port A4, and flows out of the valve group through the working port A and returns to the oil tank.

[0034] Under this operating condition, the four hydraulic motors distribute the flow, resulting in a small system flow rate. When the system pressure is constant, the output torque is the sum of the output torques of the four hydraulic motors, enabling the hydraulic rotary drill rod to output low speed and high torque.

[0035] Furthermore, when the hydraulic motor is a bidirectional motor, changing the oil inlet of the valve group and reversing the hydraulic motor can still achieve the connection of two hydraulic motors in series and then in parallel, or the connection of four hydraulic motors in parallel, in the same way as described above.

[0036] Specifically: (1) The first hydraulic directional valve 1.1 and the second hydraulic directional valve 1.2 are in the following positions: Figure 1 In the normal position shown, hydraulic oil enters the valve group through the working port A on the valve block, and is divided into two paths. One path enters the connected second hydraulic motor 52 through port A2, then through port B2 and the T and P ports of the first hydraulic directional valve 1.1, and enters the first hydraulic motor 51 through port A1. Finally, it enters the valve group again through port B1 and flows out of the valve group through the working port B, returning to the oil tank. The other path enters the connected fourth hydraulic motor 54 through port A4, then through port B4 and the T and P ports of the second hydraulic directional valve 1.2, and enters the third hydraulic motor 53 through port A3. Finally, it enters the valve group again through port B3 and flows out of the valve group through the working port B, returning to the oil tank. In this operating condition, the second hydraulic motor 52 and the first hydraulic motor 51 are connected in series, and the fourth hydraulic motor 54 and the third hydraulic motor 53 are connected in series. At the same time, the series circuit formed by the second hydraulic motor 52 and the first hydraulic motor 51 is connected in parallel with the series circuit formed by the fourth hydraulic motor 54 and the third hydraulic motor 53, which can jointly drive the hydraulic rotary table drill pipe of the workover rig to rotate.

[0037] (2) After the first hydraulic control directional valve 1.1 and the second hydraulic control directional valve 1.2 are switched via the first control port X1, they are in the right position. Hydraulic oil enters the valve assembly through the working port A on the valve block, and then splits into four paths that flow into the four hydraulic motors respectively. The first path enters the first hydraulic motor 51 connected to it through the AP oil passage of the first hydraulic directional valve 1.1 from port A1, then returns to the valve assembly through port B1, and flows out of the valve assembly through the working port B, returning to the oil tank. The second path enters the second hydraulic motor 52 connected to it through port A2, then returns to the valve assembly through port B2, flows through the TB oil passage of the first hydraulic directional valve 1.1, and flows out of the valve assembly through the working port B, returning to the oil tank. The third path enters the third hydraulic motor 53 connected to it through the AP oil passage of the second hydraulic directional valve 1.2 from port A3, then returns to the valve assembly through port B3, and flows out of the valve assembly through the working port B, returning to the oil tank. The fourth path enters the fourth hydraulic motor 54 connected to it through port A4, then returns to the valve assembly through port B4, flows through the TB oil passage of the second hydraulic directional valve 1.2, and flows out of the valve assembly through the working port B, returning to the oil tank. Under this operating condition, the four hydraulic motors distribute the flow, resulting in a small system flow rate. When the system pressure is constant, the output torque is the sum of the output torques of the four hydraulic motors, enabling the hydraulic rotary drill rod to output low speed and high torque.

[0038] Furthermore, the valve block is also equipped with four oil ports, T1, T2, T3, and T4, which are used to connect to the drain ports of the first to fourth hydraulic motors, respectively. These four oil ports are connected to the drain port T0 on the surface of the valve block via a drain oil passage within the valve block. Since the hydraulic motors themselves experience internal leakage during operation, this leakage needs to return to the oil tank via an oil passage. Therefore, the oil can enter the drain oil passage of the valve block through the drain port on the hydraulic motor, and finally return to the oil tank via drain port T0.

[0039] Furthermore, the valve block is also equipped with a relief valve. Excess oil pumped out by the hydraulic pump returns to the oil tank through the relief valve, ensuring stable oil pressure at the front end of the hydraulic motor. Since the hydraulic motor is a bidirectional motor, the same working port can be both an inlet and an outlet. To accommodate the bidirectional hydraulic motor, two relief valves are provided: a first relief valve 2.1 and a second relief valve 2.2. The inlet of the first relief valve 2.1 is connected to the oil line between working port B and ports B1 and B3. The inlet of the second relief valve 2.2 is connected to the oil line between working port A and ports A2 and A4. The outlets of the first relief valve 2.1 and the second relief valve 2.2 are connected to the return port T on the valve block through an overflow oil line. When oil enters through working port B and returns through working port A, the first relief valve 2.1 operates, and excess oil returns to the oil tank through the return port. When the valve block receives oil at working port A and returns oil at working port B, the second relief valve 2.2 operates, and excess oil returns to the oil tank via the return port T. Furthermore, the valve block also includes a first check valve 3.1 and a second check valve 3.2. The inlet of the first check valve 3.1 is connected to the overflow oil line, and its outlet is connected to the oil line between working port B and ports B1 and B3. The inlet of the second check valve 3.2 is connected to the overflow oil line, and its outlet is connected to the oil line between working port A and ports A2 and A4. When the first relief valve 2.1 operates, excess oil can also return to the oil tank through the second check valve 3.2 and then through working port A; when the second relief valve 2.2 operates, excess oil can also return to the oil tank through the first check valve 3.1 and then through working port B.

[0040] When the valve group controls the operation of the hydraulic motor, if the actuator connected to the hydraulic motor (such as the hydraulic rotary drill rod) becomes stuck, the pressure at the rear end of the hydraulic motor will rise sharply. At this time, the oil can be returned through the balance valve structure in the valve group, which consists of the first relief valve, the second relief valve, the first check valve, and the second check valve, to ensure the stability of the hydraulic system pressure.

[0041] The following discussion focuses on the first hydraulically controlled directional valve 1.1 and the second hydraulically controlled directional valve 1.2 in their respective positions. Figure 1Taking the normal operating position as an example, when oil enters through working port B and returns through working port A, if the actuator jams, the instantaneous pressure at ports A2 and A4 will increase. After a short while, the hydraulic oil at ports A2 and A4 will return to the oil tank through the second relief valve 2.2, the second check valve 3.2, and the relief oil circuit until the pressure is balanced. When oil enters through working port A and returns through working port B, if the actuator jams, the hydraulic oil at ports B1 and B3 will return to the oil tank through the first relief valve 2.1, the first check valve 3.1, and the relief oil circuit until the pressure is balanced. Under other operating conditions, the relief valve and the corresponding check valve can also work together to achieve system pressure balance, preventing system overpressure from causing damage to local parts and resulting in malfunctions.

[0042] In typical hydraulic circuit designs, both the overflow oil circuit and the drain oil circuit are connected to the oil tank. However, to prevent excessive return oil pressure in the overflow oil circuit from causing damage to the motor oil seal and resulting in hydraulic motor failure, a fifth check valve 3.5 is installed between the overflow oil circuit and the drain oil circuit in the valve group to prevent hydraulic oil in the overflow oil circuit from entering the drain port T0.

[0043] Furthermore, the valve block is also equipped with multiple oil ports for monitoring the hydraulic oil pressure. These ports include pressure testing ports M1 and M2 for monitoring the oil pressure at the hydraulic motor inlet, and a pressure relief port MT for monitoring the pressure at the hydraulic motor outlet. Pressure testing port M1 is connected to the working port B via a third check valve 3.3 and to the working port A via a fourth check valve 3.4. Pressure testing port M2 is connected to pressure testing port M1 via an oil passage within the valve block. The pressure relief port MT is connected to the drain oil passage. With the third check valve 3.3 and the fourth check valve 3.4, only one pressure testing port, M1 or M2, is needed to monitor the oil pressure at the hydraulic motor's inlet during forward and reverse rotation.

[0044] Furthermore, the valve block is also provided with two spare pressure test ports, namely spare pressure test port MA and spare pressure test port MB. Spare pressure test port MA is connected to the working port A, and spare pressure test port MB is connected to the working port B.

[0045] In this embodiment, each check valve can also be a hydraulically controlled check valve.

[0046] Example 2

[0047] See attached document Figure 2As shown, a hydraulic control system for switching the torque of multiple hydraulic motors includes the valve group in Embodiment 1, multiple solenoid directional valves, a hydraulic pump 1, and an oil tank. The multiple solenoid directional valves include a first solenoid ball valve 21, a second solenoid ball valve 22, and a three-position four-way solenoid directional valve 3. The P port of the three-position four-way solenoid directional valve 3, the P port of the first solenoid ball valve 21, and the P port of the second solenoid ball valve 22 are all connected to the outlet of the hydraulic pump 1. The T port of the three-position four-way solenoid directional valve 3, the T port of the first solenoid ball valve 21, and the T port of the second solenoid ball valve 22 are all connected to the oil tank. The A port and B port of the three-position four-way solenoid directional valve 3 are respectively connected to the working oil port A and the working oil port B on the valve block. The A port of the first solenoid ball valve 21 and the A port of the second solenoid ball valve 22 are respectively connected to the first control oil port X1 and the second control oil port X2.

[0048] The hydraulic pump 1 provides hydraulic oil to the valve group. The three-position four-way solenoid directional valve 3 can switch the working port A and working port B in the valve group in the direction of oil inlet and outlet by switching, realizing the switching of working port A inlet and working port B return, and working port B inlet and working port A return, thereby realizing the switching control of the hydraulic motor to rotate forward or backward, and meeting the needs of different working conditions.

[0049] The above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the specific implementation of this utility model with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model are within the protection scope of the pending claims.

Claims

1. A valve assembly for switching the torque of multiple hydraulic motors, comprising a valve block, characterized in that: The valve block is equipped with a first hydraulically controlled directional valve and a second hydraulically controlled directional valve; the valve block is provided with working oil port A, working oil port B and connecting oil ports for connecting four hydraulic motors, wherein the connecting oil ports for connecting the first hydraulic motor are A1 and B1, the connecting oil ports for connecting the second hydraulic motor are A2 and B2, the connecting oil ports for connecting the third hydraulic motor are A3 and B3, and the connecting oil ports for connecting the fourth hydraulic motor are A4 and B4. The first and second hydraulically controlled directional valves are three-position four-way valves. Port B of the first and second hydraulically controlled directional valves, as well as ports B1 and B3, are all connected to the working oil port B. Ports A of the first and second hydraulically controlled directional valves, as well as ports A2 and A4, are all connected to the working oil port A. Port P of the first hydraulically controlled directional valve is connected to port A1, and port T of the first hydraulically controlled directional valve is connected to port B2. Port P of the second hydraulically controlled directional valve is connected to port A3, and port T of the second hydraulically controlled directional valve is connected to port B4. The first hydraulic directional valve and the second hydraulic directional valve are also connected to the control oil circuit inside the valve block, and the control oil circuit opens at the control oil port on the surface of the valve block.

2. The valve assembly for switching torque of multiple hydraulic motors according to claim 1, characterized in that: The four hydraulic motors are bidirectional motors. The valve block is also provided with four oil ports, which are used to connect the drain ports of the four hydraulic motors respectively. The four oil ports are connected to the drain port T0 on the surface of the valve block through the drain oil passage inside the valve block.

3. The valve assembly for switching torque of multiple hydraulic motors according to claim 2, characterized in that: The valve block is also equipped with a first overflow valve and a second overflow valve. The inlet of the first overflow valve is connected to the oil line between the working oil port B and the ports B1 and B3. The inlet of the second overflow valve is connected to the oil line between the working oil port A and the ports A2 and A4. The outlets of the first overflow valve and the second overflow valve are connected to the return oil port T on the valve block through the overflow oil line.

4. The valve assembly for switching torque of multiple hydraulic motors according to claim 3, characterized in that: The valve block is also equipped with a first check valve and a second check valve. The inlet of the first check valve is connected to the overflow oil line, and the outlet of the first check valve is connected to the oil line between the working oil port B and the ports B1 and B3. The inlet of the second check valve is connected to the overflow oil line, and the outlet of the second check valve is connected to the oil line between the working oil port A and the ports A2 and A4.

5. The valve assembly for switching torque of multiple hydraulic motors according to claim 4, characterized in that: The drain port T0 is connected to the overflow oil circuit through an oil circuit equipped with a fifth check valve to prevent hydraulic oil in the overflow oil circuit from entering the drain port T0.

6. The valve assembly for switching torque of multiple hydraulic motors according to claim 2, characterized in that: The valve block is provided with a pressure testing port M1 for monitoring the oil pressure at the inlet of the hydraulic motor. The pressure testing port M1 is connected to the working port B through a third check valve and to the working port A through a fourth check valve.

7. The valve assembly for switching torque of multiple hydraulic motors according to claim 6, characterized in that: The valve block is provided with a pressure testing port M2 for monitoring the oil pressure at the inlet of the hydraulic motor. The pressure testing port M2 is connected to the pressure testing port M1 through the oil passage inside the valve block.

8. The valve assembly for switching torque of multiple hydraulic motors according to claim 1, characterized in that: The control port is provided in two forms: a first control port X1 and a second control port X2. The control ports at both ends of the first hydraulic directional valve are connected to the first control port X1 and the second control port X2, respectively. The control ports at both ends of the second hydraulic directional valve are connected to the first control port X1 and the second control port X2, respectively.

9. A hydraulic control system for switching torque between multiple hydraulic motors, characterized in that: The system includes a valve assembly as described in any one of claims 1-8, a plurality of solenoid directional valves, a hydraulic pump, and an oil tank. The plurality of solenoid directional valves include a first solenoid ball valve, a second solenoid ball valve, and a three-position four-way solenoid directional valve. The P port of the three-position four-way solenoid directional valve, the P port of the first solenoid ball valve, and the P port of the second solenoid ball valve are all connected to the outlet of the hydraulic pump. The T port of the three-position four-way solenoid directional valve, the T port of the first solenoid ball valve, and the T port of the second solenoid ball valve are all connected to the oil tank. The A port and B port of the three-position four-way solenoid directional valve are respectively connected to the working oil port A and the working oil port B on the valve block. The A port of the first solenoid ball valve and the A port of the second solenoid ball valve are respectively connected to the first control oil port X1 and the second control oil port X2.

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