An unmanned electric tractor hydraulic steering system

Abstract

The utility model relates to tractor control technical field, concretely relates to a kind of unmanned electric tractor hydraulic steering system;It contains the gear pump connected to the steering oil tank, gear pump output end forms high-pressure main oil circuit, and is connected with priority valve, priority valve is connected with pilot proportional control valve and back pressure valve, pilot proportional control valve is connected to tractor steering cylinder, for controlling its action, back pressure valve connects the hydraulic lifting system of tractor;The present application is directly controlled steering by hydraulic pressure, without tractor steering wheel and steering gear intervention, realize full-condition unmanned driving;The present application is driven by single gear pump, and oil is controlled using priority valve, according to the pressure automatic switching of steering cylinder, realize surplus flow supply lifting system when power is sufficient, to improve the utilization of hydraulic system power, reduce energy waste, realize energy saving, improve the endurance of electric tractor to some extent.

Description

Technical Field

[0001] This utility model relates to the field of tractor control technology, specifically to a hydraulic steering system for an unmanned electric tractor. Background Technology

[0002] In recent years, with the advancement of technology and the domestic energy layout, machinery has gradually developed towards intelligence and electrification. Tractors are a widely used basic agricultural equipment, and there is also a need to develop driverless electric tractors. During the operation of tractors, the steering system needs to be precisely controlled according to path planning and attitude control. Existing hydraulic steering systems are all based on manual steering wheel control, which cannot meet the needs of driverless operation. Utility Model Content

[0003] The purpose of this utility model is to address the deficiencies and shortcomings of the existing technology by providing a reasonably designed hydraulic steering system for an unmanned electric tractor, which can solve the aforementioned defects.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: it includes a gear pump connected to the steering oil tank, the output end of the gear pump forming a high-pressure main oil circuit and connected to a priority valve, the priority valve being connected to a pilot proportional control valve and a back pressure valve, the pilot proportional control valve being connected to the steering cylinder of the tractor for controlling its action, and the back pressure valve being connected to the hydraulic lifting system of the tractor.

[0005] Preferably, the priority valve is a three-position valve. In the left position, the oil supply to the pilot proportional control valve is disconnected. In the middle and right positions, the oil circuit of the pilot proportional control valve is connected. In the right position, the oil outlet is also connected to the pipeline connected to the back pressure valve.

[0006] Preferably, the tractor steering cylinder is a double-acting cylinder, with both of its ports connected to a pilot proportional control valve. The pilot proportional control valve is a three-position four-way valve, with four ports: an inlet connected to the priority valve, two working ports connected to the tractor steering cylinder, and a return port connected to the oil tank. The three positions control the tractor steering cylinder. In the neutral position, the two working ports are disconnected to achieve the neutral position of the tractor steering cylinder. In the right position, the tractor steering cylinder drives the tractor to turn left. In the left position, the oil flow direction is switched, causing the tractor steering cylinder to drive the tractor to turn right.

[0007] Preferably, the two control ports of the pilot proportional control valve are respectively connected to proportional pressure reducing valve one and proportional pressure reducing valve two, and the oil inlet of both is connected to the high-pressure main oil line.

[0008] Preferably, in the left and right positions of the pilot proportional control valve, the oil inlet is also connected to a control oil circuit, which is connected to the left control oil chamber of the priority valve. When the priority valve is in the left position, the control oil circuit is connected to the return oil circuit after passing through the priority valve.

[0009] Preferably, the control oil chamber on the right side of the priority valve is connected to the return oil circuit via a control valve, and the control oil chamber is also connected to the high-pressure main oil circuit via a one-way throttle valve.

[0010] Preferably, the gear pump is equipped with an oil suction filter on the front end pipe and a high-pressure filter on the rear end pipe.

[0011] Preferably, a spring is provided on the left side of the priority valve, so that when the priority valve is not controlled by pilot pressure, the valve core is in the left position under the action of the spring's restoring force.

[0012] Preferably, the control oil circuit between the priority valve and the pilot proportional control valve is further connected to an overflow valve, which is connected to the return oil circuit.

[0013] Preferably, a valve inlet filter screen is connected to the oil inlet of the first proportional pressure reducing valve, and a valve inlet filter screen is connected to the front end of the oil inlet of the second proportional pressure reducing valve.

[0014] The beneficial effects of this utility model after adopting the above structure are: 1. This application uses hydraulic direct control for steering, eliminating the need for a tractor steering wheel and steering gear, thus achieving fully automated driving under all working conditions.

[0015] 2. This application uses a single gear pump for driving and a priority valve to control the hydraulic fluid. The hydraulic fluid is automatically switched according to the pressure of the steering cylinder, so that when the power is sufficient, the remaining flow is supplied to the lifting system, thereby improving the power utilization rate of the hydraulic system, reducing energy waste, achieving energy saving, and improving the range of the electric tractor to a certain extent.

[0016] 3. In the steering process, the pilot proportional control valve and priority valve of this application have a fast response speed and strong steering fine adjustment capability of the tractor, which ensures the high precision of the tractor in straight line.

[0017] 4. In this application, the pilot proportional control valve is controlled by proportional pressure reducing valve one and proportional pressure reducing valve two. Compared with the valve core controlled by the proportional electromagnet, it has a large flow capacity and the valve port opening and closing is reliable and stable. Attached Figure Description

[0018] Figure 1 This is a system schematic diagram of the present invention in the middle position; Figure 2 This is a schematic diagram of the system principle of this utility model when turning left; Figure 3 This is a schematic diagram of the system principle of this utility model when turning right.

[0019] Explanation of reference numerals in the attached figures: 1. Steering oil tank; 2. Suction filter; 3. Gear pump; 4. High-pressure filter; 5. Tractor steering cylinder; 6. Back pressure valve; 7. Priority valve; 8. One-way throttle valve; 9. Control valve; 10. Valve inlet filter screen one; 11. Valve inlet filter screen two; 12. Proportional pressure reducing valve one; 13. Proportional pressure reducing valve two; 14. Throttle orifice one; 15. Throttle orifice two; 16. Pilot-operated proportional control valve; 17. Relief valve. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] See Figure 1 As shown, it includes a gear pump 3 connected to the steering oil tank 1. The front end pipe of the gear pump 3 is equipped with an oil suction filter 2, and the rear end pipe is equipped with a high pressure filter 4. The rear end forms a high pressure main oil circuit for oil supply. A priority valve 7 is connected to the high pressure main oil circuit. The priority valve 7 is connected to a pilot proportional control valve 16 and a back pressure valve 6. The pilot proportional control valve 16 is connected to the tractor steering cylinder 5 to control its action. The back pressure valve 6 is connected to the tractor's hydraulic lifting system. The priority valve 7 is a three-position valve with a spring on its left side. When the priority valve 7 is not controlled by the pilot pressure, the valve core is in the left position under the action of the spring return force. In the left position, the oil supply to the pilot proportional control valve 16 is disconnected. In the middle and right positions, the oil circuit of the pilot proportional control valve 16 is connected. When it is in the right position, the oil outlet is also connected to the pipeline connected to the back pressure valve 6. The tractor steering cylinder 5 is a double-acting cylinder, with both of its ports connected to the pilot proportional control valve 16. The pilot proportional control valve 16 is a three-position four-way valve, with four ports connected to the inlet of the priority valve 7, the two working ports of the tractor steering cylinder 5, and the return port of the oil tank. The three positions control the tractor steering cylinder 5. In the neutral position, the two working ports are disconnected to achieve the neutral position of the tractor steering cylinder 5. In the right position, the tractor steering cylinder 5 drives the tractor to turn left. In the left position, the oil flow direction is switched so that the tractor steering cylinder 5 drives the tractor to turn right. The pilot proportional control valve 16 has two control ports connected to proportional pressure reducing valve 12 and proportional pressure reducing valve 2 13 respectively. The oil inlets of both valves are connected to the high-pressure main oil line. A valve inlet filter screen 10 is connected in front of the oil inlet of proportional pressure reducing valve 12, and a valve inlet filter screen 2 11 is connected in front of the oil inlet of proportional pressure reducing valve 2 13. In the left and right positions of the pilot proportional control valve 16, the oil inlet is also connected to a control oil circuit. This oil circuit is connected to the left control oil chamber of the priority valve 7. The control oil circuit is also connected to the relief valve 17, which is connected to the return oil circuit. When the priority valve 7 is in the left position, the control oil circuit is connected to the return oil circuit after passing through the priority valve 7. The right control oil chamber of the priority valve 7 is connected to the return oil circuit through the control valve 9. The control oil chamber is also connected to the high-pressure main oil circuit through the one-way throttle valve 8. The control valve 9 is a two-position two-way control valve 9 used to control the on and off. An angle sensor is installed on the front axle of the tractor to detect the steering angle of the front wheels in real time. The host computer issues a command, and the hydraulic system controls the solenoid valve to work according to the command, so that the hydraulic oil circuit is connected. When the front wheels turn to the specified angle, the angle sensor feeds back the steering angle signal to the host computer, and then the host computer closes the valve in time, so that the hydraulic oil circuit returns to the neutral position.

[0022] The following explains the principle under different working conditions: like Figure 1 In the neutral position, i.e., when the tractor is traveling in a straight line, control valve 9 is not energized and is in the lower position. This means that the hydraulic oil in the right control chamber of priority valve 7 is discharged back to the oil tank through control valve 9. Priority valve 7 is in the left position under the action of the left spring, and the left control chamber is also connected to the return oil circuit. Proportional pressure reducing valves 12 and 13 are not energized. Hydraulic oil is pumped out by gear pump 3, filtered by suction filter 2 and high-pressure filter 4, and then sent to back pressure valve 6 after passing through priority valve 7. Back pressure valve 6 is in the lower position under the return oil pressure, supplying oil to the hydraulic lifting system. The pressure in the L and R chambers of the tractor steering cylinder 5 is balanced, and no action is performed. Back pressure valve 6 also provides pilot pressure oil to priority valve 7, proportional pressure reducing valve 12, and proportional pressure reducing valve 13. like Figure 2 The diagram shows the hydraulic circuit principle during left turn. At this time, control valve 9 is energized and connected to the upper position. Proportional pressure reducing valve 12 is also energized and connected, causing pilot proportional control valve 16 to connect to the right position, with an adjustable valve opening. The high-pressure main oil circuit, through one-way throttle valve 8, supplies oil to the right control chamber of priority valve 7. Under the pressure difference between the left and right control chambers, the valve core of priority valve 7 moves to the right, connecting to either the middle or right position. Both the middle and right positions send oil to pilot proportional control valve 16, which then connects to tractor steering cylinder 5. Therefore, the pressure in the control circuit connected to pilot proportional control valve 16 and priority valve 7 also increases. That is, the right control chamber of priority valve 7 is at high pressure from the high-pressure main oil circuit, while the left control chamber changes according to the input pressure of tractor steering cylinder 5. Priority valve 7 automatically switches based on the pressure difference. Figure 2In the right-hand operating state, gear pump 3 has sufficient pressure, indicating that there is still some pressure remaining after satisfying the steering cylinder 5 of the tractor. The excess flow can be supplied to the hydraulic lifting system through the back pressure valve 6, providing power to it. This allows a single gear pump 3 to simultaneously provide steering and lifting power, reusing hydraulic power and reducing energy waste. When the flow of gear pump 3 is low, priority valve 7 automatically switches to the neutral position, supplying only the steering cylinder 5 of the tractor. The difference between the neutral and right-hand positions lies in whether the back pressure valve 6 is engaged or disengaged, and therefore it is not shown separately in the attached diagram. Figure 2 Taking the priority valve 7 in the right position as an example, the oil pumped by the gear pump 3 is sent to the pilot proportional control valve 16 in the right position after passing through the priority valve 7 in the right position. Then, it enters the L chamber of the tractor steering cylinder 5 through the priority valve 7 in the right position to achieve left turn. The oil in the R chamber of the tractor steering cylinder 5 is sent to the pilot proportional control valve 16 in the right position through the priority valve 7 in the right position, and then discharged back to the oil tank. The remaining flow in the priority valve 7 is sent to the hydraulic lifting system through the back pressure valve 6. After the host computer obtains the signal that the left turn has reached the end of the stroke according to the angle sensor, the pressure oil opens the relief valve 17, and the high pressure oil in the pilot proportional control valve 16 is discharged back to the oil tank through the relief valve 17 to protect the safety of the hydraulic system. like Figure 3 The diagram shows the hydraulic circuit for right turns. Control valve 9 and proportional pressure reducing valve 13 are energized. The difference from left turns is that proportional pressure reducing valve 13 enables pilot proportional control valve 16 to be open in the left position through throttle orifice 15, exchanging the oil circuits connected to the R and L chambers of tractor steering cylinder 5. Thus, oil enters the R chamber of tractor steering cylinder 5 and returns oil to the L chamber, achieving right turns. In both the left and right positions of pilot proportional control valve 16, the control oil circuit connected to priority valve 7 is connected to the oil inlet. Therefore, similar to left turns, priority valve 7 automatically switches between the middle and right positions, supplying hydraulic lifting system when there is excess hydraulic oil flow.

[0023] The installation, connection, or setting methods of the components not detailed above are all common mechanical methods, and the specific structure, model, and coefficient indicators of all their components are their own technologies. As long as they can achieve their beneficial effects, they can be implemented, so they will not be elaborated further.

[0024] It should be understood that the above-described specific embodiments of this utility model are merely illustrative or explanatory of the principles of this utility model and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this utility model should be included within the protection scope of this utility model. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A hydraulic steering system for an unmanned electric tractor, comprising a gear pump (3) connected to a steering oil tank (1), wherein the output end of the gear pump (3) forms a high-pressure main oil circuit, characterized in that: A priority valve (7) is connected to the high-pressure main oil line. The priority valve (7) is connected to a pilot proportional control valve (16) and a back pressure valve (6). The pilot proportional control valve (16) is connected to the tractor steering cylinder (5) to control its action. The back pressure valve (6) is connected to the tractor's hydraulic lifting system.

2. The hydraulic steering system for an unmanned electric tractor according to claim 1, characterized in that: The priority valve (7) is a three-position valve. When it is in the left position, it disconnects the oil supply to the pilot proportional control valve (16). When it is in the middle and right positions, it connects the oil circuit of the pilot proportional control valve (16). When it is in the right position, the oil outlet is also connected to the pipeline connected to the back pressure valve (6).

3. The hydraulic steering system for an unmanned electric tractor according to claim 2, characterized in that: The tractor steering cylinder (5) is a double-acting cylinder. Both of its oil ports are connected to the pilot proportional control valve (16). The pilot proportional control valve (16) is a three-position four-way valve. The four oil ports are respectively the oil inlet of the priority valve (7), the two working oil ports of the tractor steering cylinder (5), and the oil return port of the oil tank. The three positions control the tractor steering cylinder (5). When it is in the middle position, the two working oil ports are disconnected to achieve the middle position of the tractor steering cylinder (5). When it is in the right position, the tractor steering cylinder (5) drives the tractor to turn left. When it is in the left position, the oil flow direction is switched so that the tractor steering cylinder (5) drives the tractor to turn right.

4. The hydraulic steering system for an unmanned electric tractor according to claim 3, characterized in that: The two control ports of the pilot proportional control valve (16) are respectively connected to proportional pressure reducing valve one (12) and proportional pressure reducing valve two (13), and the oil inlets of both are connected to the high-pressure main oil line.

5. The hydraulic steering system for an unmanned electric tractor according to claim 3, characterized in that: In the left and right positions of the pilot proportional control valve (16), the oil inlet is also connected to a control oil circuit, which is connected to the left control oil chamber of the priority valve (7). When the priority valve (7) is in the left position, the control oil circuit is connected to the return oil circuit through the priority valve (7).

6. The hydraulic steering system for an unmanned electric tractor according to claim 5, characterized in that: The control oil chamber on the right side of the priority valve (7) is connected to the return oil circuit through the control valve (9), and the control oil chamber is also connected to the high-pressure main oil circuit through the one-way throttle valve (8).

7. The hydraulic steering system for an unmanned electric tractor according to claim 1, characterized in that: The gear pump (3) is equipped with an oil suction filter (2) on the front end pipe and a high pressure filter (4) on the rear end pipe.

8. The hydraulic steering system for an unmanned electric tractor according to claim 2, characterized in that: A spring is provided on the left side of the priority valve (7). When the priority valve (7) is not controlled by the pilot pressure, the valve core is in the left position under the action of the spring reset force.

9. A hydraulic steering system for an unmanned electric tractor according to claim 5, characterized in that: The control oil circuit between the priority valve (7) and the pilot proportional control valve (16) is also connected to an overflow valve (17), which is connected to the return oil circuit.

10. A hydraulic steering system for an unmanned electric tractor according to claim 4, characterized in that: The proportional pressure reducing valve one (12) is connected to the inlet of the valve inlet filter one (10), and the proportional pressure reducing valve two (13) is connected to the inlet of the valve inlet filter two (11).

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