Parallel hydraulic steering system of unmanned tractor

Abstract

The invention discloses a parallel hydraulic steering system of an unmanned tractor, which relates to the field of hydraulic steering systems and comprises a hydraulic steering module, a middle-position hydraulic module, a manual left steering hydraulic module, an unmanned left steering hydraulic module, an overload protection module and a system fault analysis module. And a middle-position hydraulic module, a manual left steering hydraulic module and an unmanned left steering hydraulic module are arranged in the hydraulic steering module. According to the parallel hydraulic steering system of the unmanned tractor, when the tractor normally runs in a straight line, a steering gear and a steering control valve set do not work, due to the fact that the ground is uneven and a steering oil cylinder is impacted by pressure, a first overload overflow valve and a first oil supplementing one-way valve are arranged for protecting the oil cylinder; the oil cylinder B port reaches the overload overflow valve to the T port and returns to the oil tank; meanwhile, the T-port oil return box reaches the first oil supplementing one-way valve to the left cavity of the A port of the steering oil cylinder, and the oil cylinder is prevented from being impacted and the left cavity is prevented from sucking air.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic steering systems, in particular to a parallel hydraulic steering system for an unmanned tractor. Background Art

[0002] The parallel hydraulic steering system of the driverless tractor is a technology used to achieve precise steering control. In this system, the hydraulic system is usually designed in a parallel structure to improve the flexibility and response speed of steering. In the prior art, it is inconvenient to switch between human-driven and unmanned driving modes, which is not conducive to the use of the user, and it is inconvenient to switch between different driving modes in different environments; In order to overcome the above shortcomings, the Chinese patent of the prior art (Announcement No. CN111086560A) discloses a hydraulic steering system compatible with manual driving and unmanned driving modes, including a hydraulic steering cylinder connected to two front wheels of the car, an angle sensor connected to one front wheel, a hydraulic station and an unmanned driving controller. The hydraulic steering system can adopt manual hydraulic steering or unmanned driving hydraulic steering operation according to the needs of the driver and the road, and in the case of one of the manual hydraulic steering and unmanned driving hydraulic steering out of control, another steering method can be adopted to drive the vehicle to the destination. The system has high compatibility; In order to overcome the above shortcomings, the Chinese patent of the prior art (Announcement No. CN107662639A) discloses a tractor hydraulic steering system, including a fuel tank, a steering hydraulic pump, a steering gear and a steering actuator, wherein the fuel tank, the steering hydraulic pump, the steering gear and the steering actuator are connected in sequence through oil pipes, and a control system and a solenoid valve are arranged between the fuel tank and the steering actuator, and the opening and closing of the solenoid valve are controlled by the control system to realize the automatic steering function; the technical solution is adopted to reduce the burden of manual operation, and at the same time does not affect the conventional steering work of the tractor, ensures normal agricultural production, saves production costs, and improves work efficiency; Although the existing technology can overcome the above-mentioned deficiencies, there are still other problems in its operation process, such as: when the system is running, it is easy to cause the system to collapse due to excessive flow, which is not conducive to the use of the system and affects the service life of the system. Summary of the invention

[0003] The purpose of the present invention is to provide a parallel hydraulic steering system for an unmanned tractor to solve the problem in the above background technology that when the system is running, it is easy to cause the system to collapse due to excessive flow, which is not conducive to the use of the system and affects the service life of the system.

[0004] To achieve the above object, the present invention provides the following technical solutions: a parallel hydraulic steering system for an unmanned tractor, the system comprising a hydraulic steering module, a neutral hydraulic module, a manual left steering hydraulic module, an unmanned left steering hydraulic module, an overload protection module and a system fault analysis module; The hydraulic steering module is provided with a neutral hydraulic module, a manual left steering hydraulic module and an unmanned left steering hydraulic module inside, and an overload protection module is provided below the hydraulic steering module, and a system fault analysis module is provided below the overload protection module; The hydraulic steering module is composed of an oil suction filter, a gear pump, a high-pressure filter, a steering control valve group, a steering gear, and a steering cylinder. A gear pump is arranged above the oil suction filter, and a high-pressure filter is arranged above the gear pump. A steering control valve group is arranged above the right side of the high-pressure filter, and a steering gear is arranged above the left side of the high-pressure filter. A steering cylinder is arranged above the steering control valve group and the steering gear. The neutral hydraulic module refers to the state where the tractor steering wheel is not turned, the steering gear is not working, and the steering control valve group is not powered; The manual left steering hydraulic module: during manual steering, the driver manipulates the tractor steering wheel, the hydraulic steering gear works, the front wheels steer, and the hydraulic control of the tractor's left steering is controlled through the conversion of the oil circuit; The unmanned left steering hydraulic module: when the unmanned driving needs to turn, the controller controls the proportional reversing valve to be energized, and the pressure oil of the gear pump enters the steering cylinder through the steering control valve group, and the front wheel turns. When the tractor is unmanned and needs to turn left, the controller sends a signal to energize the left position of the proportional reversing valve. The greater the current, the greater the opening of the proportional reversing valve, and the greater the flow rate. The excess flow will return to the oil tank through the pressure compensation valve and the middle position of the steering gear; The overload protection module is internally provided with a first overload relief valve and a first oil replenishment check valve to protect the pressure inside the steering system; The system fault analysis module: when the steering wheel is turned left manually, the front wheel deflects to the end of the stroke. When turning right, the front wheel does not move, and the front wheel turns left normally, indicating that the gear pump, the tank liquid level, and the oil suction filter are normal; the rubber hose connecting the steering gear and the B port of the front axle cylinder is disassembled on site, the plug is connected, the vehicle is started, the steering wheel is turned right, the steering wheel sinks, and there is an obvious overflow sound in the steering gear, indicating that the steering gear is normal, the hydraulic oil has reached the B port of the front axle cylinder, and the hydraulic oil has leaked. The leakage paths include the cylinder and the steering control valve group; the pipeline between the steering control valve group and the front axle cylinder is disconnected, and the vehicle is restarted. The steering returns to normal, indicating that the hydraulic oil has leaked through the steering control valve group; the hydraulic control one-way valve is disassembled, and impurities such as aluminum chips are found in the valve port. After cleaning, it is reinstalled, and the rotation control valve group and the front axle pipeline are reconnected at the same time. The vehicle is started, the steering returns to normal, and the fault is eliminated.

[0005] Furthermore, the hydraulic steering module automatically uses three steering module settings and can use different coping methods according to different situations to ensure the normal operation of the device.

[0006] Furthermore, the hydraulic oil circuit inside the neutral hydraulic module runs from the oil suction filter to the gear pump to the high-pressure filter to the pressure compensation valve (the valve has a set pressure of 12 bar, and its spring chamber passes through the throttle hole to the shuttle valve to the proportional reversing valve in the neutral position to the T port back to the oil tank) to the steering valve sleeve (neutral state) to the steering valve core (neutral state) to the steering valve sleeve (neutral state) to the steering control valve group T port to the hydraulic oil tank.

[0007] Furthermore, the manual left steering hydraulic module hydraulic steering gear and steering valve core, the driver turns the steering wheel to the left position of the steering valve core, the oil suction filter to the gear pump to the high-pressure filter to the pressure compensation valve to the steering valve sleeve (left position) to the steering valve core (left position) to the right inlet of the metering motor to the left outlet of the metering motor to the steering valve sleeve (left position) to the steering cylinder A port (the steering cylinder piston rod moves right, driving the front wheel to turn left through the front axle) to the steering cylinder B port to the steering valve sleeve (left position) to the steering valve core (left position) to the steering valve sleeve (left position) to the steering control valve group T port to the hydraulic oil tank.

[0008] Furthermore, the unmanned left-steering hydraulic module includes an oil circuit of the steering control valve group. The controller sends a left steering signal to the proportional reversing valve left position to obtain electricity. The specific oil circuit is: oil suction filter to gear pump to high-pressure filter to the proportional reversing valve left position to the hydraulically controlled one-way valve (the hydraulically controlled one-way valve is opened at the same time) to the steering cylinder A port (the steering cylinder piston rod moves to the right, driving the front wheel to turn left through the front axle) to the steering cylinder B port to the hydraulically controlled one-way valve to the proportional reversing valve left position to the T port back to the oil tank.

[0009] Furthermore, the unmanned left-steering hydraulic module controls the proportional reversing valve to be energized through the unmanned driving controller, and the pressure compensating valve controls the oil circuit. When the proportional reversing valve is energized, its valve port opens. The greater the current, the larger the valve port opening, and the more flow passes through. The pressure difference generated by the flow through the proportional reversing valve opening will be fed back to the high and low pressure ends of the pressure compensating valve. When the flow through the valve port exceeds the corresponding value of the controller, the valve port pressure difference exceeds 12 bar, opening the pressure compensating valve port, and the excess flow passes through the pressure compensating valve to the middle position of the steering gear and returns to the oil tank at the T port.

[0010] Furthermore, the overload protection module includes a first overload relief valve and a first oil replenishment check valve provided for protecting the oil cylinder. When the tractor is driving in a straight line normally, the steering gear and the steering control valve group do not work. Due to the unevenness of the ground, the steering cylinder is subjected to pressure shock. In order to protect the oil cylinder, a first overload relief valve and a second oil replenishment check valve are provided. Assuming that the steering cylinder piston is impacted and moves right, the oil cylinder B port (right chamber pressure oil) goes to the second overload relief valve to the T port return oil tank; at the same time, the T port return oil tank goes to the first oil replenishment check valve to the left chamber of the steering cylinder A port to prevent the left chamber from being sucked into the air.

[0011] Furthermore, the one-way valve of the overload protection module separates the tractor hydraulic steering from the tractor flameout steering oil circuit. The one-way valve separates the tractor hydraulic steering from the tractor flameout steering oil circuit. When the tractor flames out and turns, the metering motor acts as a metering pump, and the hydraulic oil flows from the T port of the oil tank to the one-way valve to the steering gear to the steering cylinder.

[0012] Furthermore, the overload protection module controls the high and low pressure ends of the pressure compensation valve to be the same through the first relief valve and the second relief valve. If the first relief valve and the second relief valve are removed, when the tractor is in an unmanned steering state, the front wheels turn to the end of the stroke, the high and low pressure ends of the pressure compensation valve are the same, the valve port is closed under the action of spring force, and the system pressure increases infinitely, which will damage the gear pump and destroy the weak link of the hydraulic system.

[0013] Furthermore, the system fault analysis module controls the valve port through the proportional reversing valve. The control logic of unmanned driving steering is that the controller sends a steering angle signal, the proportional reversing valve is energized, the valve port opens, the gear pump hydraulic oil enters the front axle cylinder, and the front axle tire turns; at the same time, the angle sensor senses the steering angle of the front axle. When the steering angle reaches the controller set value, the controller sends a proportional reversing valve power-off signal, the proportional reversing valve is immediately powered off, the gear pump is unloaded, and the tire stops rotating. After the control system energizes the proportional reversing valve, it fails to detect the steering angle signal of the angle sensor and fails to de-energize the proportional reversing valve in time, resulting in the front wheels swinging at the left and right extreme positions and failing to steer as required. After re-debugging the program, the fault is eliminated.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. When the tractor is driving normally in a straight line, the steering gear and the steering control valve group do not work. Due to the uneven ground, the steering cylinder is subjected to pressure shock. In order to protect the cylinder, the first overload relief valve and the first oil replenishment check valve are set. When the steering cylinder piston rod is impacted and moves right, the cylinder B port (right chamber pressure oil) goes to the second overload relief valve to the T port and returns to the oil tank; at the same time, the T port returns to the oil tank to the first oil replenishment check valve to the left chamber of the steering cylinder A port to prevent the cylinder from being impacted and the left chamber from being sucked empty; 2. This one-way valve separates the tractor hydraulic steering and the tractor flameout steering oil circuit. When the tractor flameouts and turns, the metering motor acts as a metering pump, and the hydraulic oil flows from the T port of the oil tank to the one-way valve to the steering gear to the steering cylinder, realizing the flameout steering function; 3. The pressure of the steering system is controlled by the first relief valve and the second relief valve, that is, the maximum thrust of the front axle cylinder is controlled. The first relief valve and the second relief valve cannot be omitted. When the tractor is in an unmanned steering state, the front wheels turn to the end of the stroke, the high and low pressure ends of the pressure compensation valve are the same, and the valve port is closed under the action of the spring force. The first relief valve and the second relief valve are used to prevent the system pressure from rising infinitely, prevent the gear pump from being damaged, and avoid damaging the weak links of the hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a general schematic diagram of the present invention; Figure 2 This is a hydraulic schematic diagram of the human left steering of the present invention; Figure 3 It is a hydraulic schematic diagram of the unmanned left turn of the present invention; Figure 4 It is a schematic diagram of the hydraulically controlled one-way valve of the present invention; Figure 5 This is a schematic diagram of a first overflow valve of the present invention; Figure 6 It is a schematic diagram of the shuttle valve of the present invention.

[0016] In the figure: 1. Oil suction filter; 2. Gear pump; 3. High-pressure filter; 4. Steering control valve group; 5. Steering gear; 6. Steering cylinder; 4.1. Hydraulic control one-way valve; 4.2. Hydraulic control one-way valve; 4.3. Shuttle valve; 4.4. Proportional reversing valve; 4.5. Throttle hole; 4.6. First overflow valve; 4.7. Pressure compensation valve; 5.1. First overload overflow valve; 5.2. Second overload overflow valve; 5.3. First oil replenishment one-way valve; 5.4. Second oil replenishment one-way valve; 5.5. Steering valve core; 5.6. Steering valve sleeve; 5.7. One-way valve; 5.8. Metering motor; 5.9. Second overflow valve. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1: Figure 1 and Figure 6The technical solution shown discloses that: the system includes a hydraulic steering module, a neutral hydraulic module, a manual left steering hydraulic module, an unmanned left steering hydraulic module, an overload protection module and a system fault analysis module; The hydraulic steering module is internally provided with a neutral hydraulic module, a manual left steering hydraulic module and an unmanned left steering hydraulic module, and an overload protection module is provided below the hydraulic steering module, and a system fault analysis module is provided below the overload protection module; Hydraulic steering module: It is composed of an oil suction filter 1, a gear pump 2, a high-pressure filter 3, a steering control valve group 4, a steering gear 5, and a steering cylinder 6. The gear pump 2 is arranged above the oil suction filter 1, and the high-pressure filter 3 is arranged above the gear pump 2. The steering control valve group 4 is arranged above the right side of the high-pressure filter 3, and the steering gear 5 is arranged above the left side of the high-pressure filter 3. The steering cylinder 6 is arranged above the steering control valve group 4 and the steering gear 5; Neutral hydraulic module: refers to the state where the tractor steering wheel is not turned, the steering gear 5 is not working, and the steering control valve group 4 is not powered; The hydraulic steering module automatically ensures the normal operation of the device through the settings of three steering modules.

[0019] The hydraulic oil circuit inside the neutral hydraulic module runs from the suction filter 1 to the gear pump 2 to the high-pressure filter 3 to the pressure compensation valve 4.7 (the valve is set to a pressure of 12 bar, and its spring chamber passes through the throttle hole 4.5 to the shuttle valve 4.3 to the proportional reversing valve 4.4, and then returns to the oil tank at the neutral position at port T), to the steering valve sleeve 5.6 (neutral state), to the steering valve core 5.5 (neutral state), to the steering valve sleeve 5.6 (neutral state), to the steering control valve group 4T port, and then to the hydraulic oil tank.

[0020] Embodiment 2: Figures 1 to 4 The technical solution shown discloses: a manual left steering hydraulic module: when the driver operates the tractor steering wheel, the hydraulic steering gear 5 works, the front wheels steer, and the hydraulic control of the tractor's left steering is controlled by the conversion of the oil circuit; Unmanned left steering hydraulic module: When the unmanned driving needs to turn, the controller controls the proportional reversing valve 4.4 to be energized, and the pressure oil of the gear pump 2 enters the steering cylinder 6 through the steering control valve group 4, and the front wheel turns. When the tractor is unmanned and needs to turn left, the controller sends a signal to energize the proportional reversing valve 4.4 to the left position. The greater the current, the greater the opening of the proportional reversing valve 4.4, and the greater the flow rate. The excess flow will pass through the pressure compensation valve 4.7 and the steering gear middle position back to the oil tank; The manual left steering hydraulic module includes a hydraulic steering gear 5 and a steering valve core 5.5. The driver turns the steering wheel to the left position of the steering valve core 5.5. The hydraulic oil circuit of the manual left steering hydraulic module runs from the oil suction filter 1 to the gear pump 2 to the high-pressure filter 3 to the pressure compensation valve 4.7 to the steering valve sleeve 5.6 (left position) to the steering valve core 5.5 (left position) to the right inlet of the metering motor 5.8 to the left outlet of the metering motor 5.8 to the steering valve sleeve 5.6 (left position) to the steering cylinder 6A port (the steering cylinder piston rod moves right, driving the front wheel to turn left through the front axle) to the steering cylinder 6B port to the steering valve sleeve 5.6 (left position) to the steering valve core 5.5 (left position) to the steering valve sleeve 5.6 (left position) to the steering control valve group 4T port to the hydraulic oil tank.

[0021] The unmanned left steering hydraulic module includes the oil circuit of the steering control valve group 4, the steering control valve group oil circuit, and the controller sends a left steering signal to the proportional reversing valve 4.4 left position to obtain electricity. The specific oil circuit is: oil suction filter 1 to gear pump 2 to high-pressure filter 3 to proportional reversing valve left position 4.4 to hydraulic control one-way valve 4.1 (open hydraulic control one-way valve 4.2 at the same time) to steering cylinder A port 6 (steering cylinder piston rod moves right, driving the front wheel to turn left through the front axle) to steering cylinder 6B port to hydraulic control one-way valve 4.2 to proportional reversing valve 4.4 left position to T port back to the oil tank.

[0022] The unmanned left steering hydraulic module controls the proportional reversing valve 4.4 to be energized through the unmanned driving controller, and the pressure compensation valve 4.7 controls the oil circuit. When the proportional reversing valve 4.4 is energized, its valve port opens. The greater the current, the greater the valve port opening, and the more flow passes through. The pressure difference generated by the flow through the opening of the proportional reversing valve 4.4 will be fed back to the high and low pressure ends of the pressure compensation valve 4.7. When the flow through the valve port exceeds the corresponding value of the controller, the valve port pressure difference exceeds 1.2bar, and the valve port of the pressure compensation valve 4.7 is opened. The excess flow passes through the pressure compensation valve 4.7 to the middle position of the steering gear to the T port and returns to the oil tank.

[0023] Embodiment 3: Figures 1 to 6 The technical solution shown in the figure discloses: an overload protection module: a first overload relief valve 5.1, a second overload relief valve 5.2, a first oil replenishment check valve 5.3, and a second oil replenishment check valve 5.4 are arranged inside the module to protect the pressure inside the steering system; System fault analysis module: When the steering wheel is turned left manually, the front wheel deflects to the end of the stroke. When turning right, the front wheel does not move, and the front wheel turns left normally, indicating that the gear pump 2, the tank liquid level, and the oil suction filter are normal; the rubber hose connecting the steering gear 5 and the B port of the front axle cylinder is disassembled on site, the plug is connected, the vehicle is started, the steering wheel is turned right, the steering wheel sinks, and there is an obvious overflow sound in the steering gear, indicating that the steering gear 5 is normal, the hydraulic oil has reached the B port of the front axle cylinder, and the hydraulic oil is leaking. The leakage path is the cylinder and the steering control valve group 4; the pipeline between the steering control valve group 4 and the front axle cylinder is disconnected, and the vehicle is restarted. The steering returns to normal, indicating that the hydraulic oil leaked through the steering control valve group 4; the hydraulic control one-way valve 4.2 is disassembled, and impurities such as aluminum chips are found in the valve port. After cleaning, it is reinstalled, and the rotation control valve group 4 and the front axle pipeline are reconnected. The vehicle is started, the steering returns to normal, and the fault is eliminated; The overload protection module includes a first overload relief valve 5.1 and a first oil replenishment check valve 5.3 provided for protecting the oil cylinder, wherein the hydraulic oil circuit of the overload protection module runs from the oil cylinder B port to the second overload relief valve 5.2 to the T port return oil tank, and from the T port return oil tank to the first oil replenishment check valve 5.3 to the left chamber of the steering oil cylinder 6A port. When the tractor is normally traveling in a straight line, the steering gear 5 and the steering control valve group 4 do not work. Due to the uneven ground, the steering oil cylinder 6 is subjected to pressure shock. In order to protect the oil cylinder, the first overload relief valve 5.1, the second overload relief valve 5.2, the first oil replenishment check valve 5.3, and the second oil replenishment check valve 5.4 are provided. Assuming that the piston cylinder of the steering oil cylinder 6 is impacted and moves rightward, the oil cylinder B port (right chamber pressure oil) goes to the second overload relief valve 5.2 to the T port return oil tank; at the same time, the T port return oil tank goes to the first oil replenishment check valve 5.3 to the left chamber of the steering oil cylinder 6A port to prevent the left chamber from being sucked empty.

[0024] The one-way valve 5.7 of the overload protection module separates the tractor hydraulic steering from the tractor flameout steering oil circuit. The one-way valve 5.7 functions to separate the tractor hydraulic steering from the tractor flameout steering oil circuit. When the tractor flameouts and turns, the metering motor 5.8 acts as a metering pump, and the hydraulic oil returns from the tank T port of the middle position to the one-way valve 5.7 to the steering gear 5 to the steering cylinder 6.

[0025] The overload protection module controls the high and low pressure ends of the pressure compensation valve 4.7 to be the same through the first relief valve 4.6 and the second relief valve 5.9. If the relief valve 4.6 and the second relief valve 5.9 are removed, when the tractor is in an unmanned steering state, the front wheels turn to the end of the stroke, the high and low pressure ends of the pressure compensation valve 4.7 are the same, the valve port is closed under the action of the spring force, and the system pressure rises infinitely, which damages the gear pump 2 and destroys the weak link of the hydraulic system; The system fault analysis module controls the valve port through the proportional reversing valve 4.4. The control logic of the unmanned steering is that the controller sends a steering angle signal, the proportional reversing valve 4.4 is powered, the valve port is opened, the hydraulic oil in the gear pump 2 enters the front axle cylinder, and the front axle tire turns; at the same time, the angle sensor senses the steering angle of the front axle. When the steering angle reaches the controller setting value, the controller sends a power-off signal of the proportional reversing valve 4.4, the proportional reversing valve 4.4 is immediately powered off, the gear pump 2 is unloaded, and the tire stops rotating. After the control system energized the proportional reversing valve 4.4, it failed to detect the steering angle signal of the angle sensor and failed to de-energize the proportional reversing valve 4.4 in time. As a result, the front wheels swung at the left and right extreme positions and failed to turn as required. After re-debugging the program, the fault was eliminated.

[0026] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A parallel hydraulic steering system for an unmanned tractor, the system comprising a hydraulic steering module, characterized in that: The system also includes a neutral hydraulic module, a manpower left steering hydraulic module, an unmanned left steering hydraulic module, an overload protection module and a system fault analysis module; The hydraulic steering module is provided with a neutral hydraulic module, a manual left steering hydraulic module and an unmanned left steering hydraulic module inside, and an overload protection module is provided below the hydraulic steering module, and a system fault analysis module is provided below the overload protection module; The hydraulic steering module is composed of an oil suction filter (1), a gear pump (2), a high-pressure filter (3), a steering control valve group (4), a steering gear (5), and a steering cylinder (6); the gear pump (2) is arranged above the oil suction filter (1), the high-pressure filter (3) is arranged above the gear pump (2), the steering control valve group (4) is arranged above the right side of the high-pressure filter (3), and the steering gear (5) is arranged above the left side of the high-pressure filter (3); and the steering cylinder (6) is arranged above the steering control valve group (4) and the steering gear (5); The overload protection module is internally provided with a first overload relief valve (5.1), a second overload relief valve (5.2), a first oil replenishment check valve (5.3), and a second oil replenishment check valve (5.4); the overload protection module protects the pressure inside the steering system.

2. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The hydraulic steering module automatically ensures the normal operation of the device through the setting of three steering modules, wherein the three steering modules are respectively a neutral hydraulic module, a manpower left steering hydraulic module and an unmanned left steering hydraulic module.

3. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The hydraulic oil circuit inside the mid-position hydraulic module runs from the oil suction filter (1) to the gear pump (2) to the high-pressure filter (3) to the pressure compensation valve (4.7) to the steering valve sleeve (5.6) to the steering valve core (5.5) to the steering valve sleeve (5.6) to the steering control valve group (4) T port to the hydraulic oil tank. The pressure of the pressure compensation valve (4.7) is 12 bar. The pressure compensation valve (4.7) passes through the throttle hole (4.5) to the shuttle valve (4.3) to the proportional reversing valve (4.4) to the T port back to the oil tank.

4. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The manual left steering hydraulic module comprises a hydraulic steering gear (5) and a steering valve core (5.5), wherein the hydraulic oil circuit of the manual left steering hydraulic module runs from an oil suction filter (1) to a gear pump (2) to a high-pressure filter (3) to a pressure compensation valve (4.7) to a steering valve sleeve (5.6) to a steering valve core (5.5) to a right inlet of a metering motor (5.8) to a left outlet of the metering motor (5.8) to a steering valve sleeve (5.6) to a steering cylinder (6) A port to a steering cylinder (6) B port to a steering valve sleeve (5.6) to a steering valve core (5.5) to a steering valve sleeve (5.6) to a T port of a steering control valve group (4) to a hydraulic oil tank.

5. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The unmanned left steering hydraulic module comprises an oil circuit of a steering control valve group (4), wherein a controller sends a left steering signal to the proportional reversing valve (4.4) left position to obtain power, and the specific oil circuit is: an oil suction filter (1) to a gear pump (2) to a high-pressure filter (3) to the proportional reversing valve (4.4) left position to a hydraulically controlled one-way valve (4.2) (4.1) to a steering cylinder (6) A port to a steering cylinder (6) B port to a hydraulically controlled one-way valve (4.2) (4.1) to the proportional reversing valve (4.4) left position to a T port back to the oil tank.

6. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The unmanned left steering hydraulic module controls the proportional reversing valve (4.4) to be energized through the unmanned driving controller, wherein the pressure oil of the gear pump (2) enters the steering cylinder (6) through the steering control valve group (4), and the controller sends a signal to make the proportional reversing valve (4.4) energized in the left position, and the current and the flow of the proportional reversing valve (4.4) control the oil circuit through the pressure compensation valve (4.7) and the middle position return oil tank and the pressure compensation valve (4.7) in the steering gear (5).

7. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The overload protection module comprises a first overload relief valve (5.1) and a first oil replenishment check valve (5.3) provided for protecting the oil cylinder, wherein the hydraulic oil circuit of the overload protection module runs from the B port of the oil cylinder to the second overload relief valve (5.2) to the T port return oil tank, and from the T port return oil tank to the first oil replenishment check valve (5.3) to the left chamber of the A port of the steering oil cylinder (6).

8. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The one-way valve (5.7) of the overload protection module separates the tractor hydraulic steering and the tractor flameout steering oil circuits, and the metering motor (5.8) is used as a metering pump. The hydraulic oil flows from the tank T port of the mid-position return tank to the one-way valve (5.7) to the steering gear (5) to the steering cylinder (6).

9. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The overload protection module controls the high and low pressure ends of the pressure compensation valve (4.7) to be the same pressure through the first relief valve (4.6) and the second relief valve (5.9).

10. The unmanned tractor parallel hydraulic steering system according to claim 1, characterized in that: The system fault analysis module is electrically controlled via the proportional reversing valve (4.4) to control the valve port, wherein the hydraulic oil in the gear pump (2) enters the front axle oil cylinder via the proportional reversing valve (4.4).

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