Hydraulic control system and control method for leafy vegetable harvester

Abstract

The present application relates to a kind of hydraulic control system and control method for leaf vegetable harvester, including front wheel steering hydraulic system, rear wheel drive hydraulic system and header lifting hydraulic system, front wheel steering hydraulic system realizes the front wheel steering of leaf vegetable harvester, rear wheel drive hydraulic system realizes the advance and retreat of leaf vegetable harvester, and header lifting hydraulic system realizes the leaf vegetable harvesting start of leaf vegetable harvester;The present application gathers together to drive rear wheel advance or retreat and front wheel steering with header lifting, guarantee stable transmission process and reduce the labor intensity of operator.

Description

Technical Field

[0001] This invention relates to a hydraulic control system and control method for a leafy vegetable harvester, belonging to the technical field of hydraulic control systems. Background Technology

[0002] Leafy vegetable harvesters are generally driven by an engine or electric motor, and their movement methods are divided into tracked and wheeled types. In common leafy vegetable harvesters, the cutter blades are located at the front of the header. After cutting the leafy vegetables, a conveyor belt on the header transports the cut vegetables to a collection box behind the header. Most existing harvesters use electric or mechanical transmission to operate their various working components. Mechanical transmission is usually more complex and difficult to repair when malfunctions occur; electric transmission is not suitable for long-term operation in outdoor fields.

[0003] Existing leafy vegetable harvesters typically only use hydraulic transmission in the header section, lacking an integrated hydraulic system. Therefore, we need to design a control system for leafy vegetable harvesters that adopts a fully hydraulic control mode to improve the stability of leafy vegetable harvesting and extend the service life of the machinery. Summary of the Invention

[0004] This invention provides a hydraulic control system and control method for a leafy vegetable harvester, which integrates the lifting and lowering of the cutting platform, driving the rear wheels forward or backward, and steering the front wheels, ensuring a stable transmission process and reducing the labor intensity of the operator.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A hydraulic control system for a leafy vegetable harvester.

[0007] It includes a front wheel steering hydraulic system, a rear wheel drive hydraulic system, and a cutting platform lifting hydraulic system. The three hydraulic systems are connected to each other and connected to the oil tank through an overflow valve and a hydraulic pump.

[0008] The front wheel steering hydraulic system enables the front wheels of the leafy vegetable harvester to steer, the rear wheel drive hydraulic system enables the leafy vegetable harvester to move forward and backward, and the header lifting hydraulic system enables the leafy vegetable harvester to start harvesting.

[0009] As a further preferred embodiment of the present invention,

[0010] The front wheel steering hydraulic system includes a double-acting steering lever hydraulic cylinder and a first solenoid directional valve. The telescopic end of the double-acting steering lever hydraulic cylinder is connected to the front wheel, the fixed end of the double-acting steering lever hydraulic cylinder is connected to one end of the first solenoid directional valve, and the other end of the first solenoid directional valve is connected to both the relief valve and the hydraulic pump.

[0011] As a further preferred embodiment of the present invention,

[0012] The rear-wheel drive hydraulic system includes two hydraulic motors, a first shuttle valve, a second shuttle valve, a third shuttle valve, a fourth shuttle valve, a second solenoid directional valve, and a third solenoid directional valve.

[0013] Two check valves and two relief valves are connected in parallel to form a buffer braking circuit. Each hydraulic motor is connected to a buffer braking circuit to form a hydraulic motor circuit. The two hydraulic motor circuits are defined as the first hydraulic motor circuit and the second hydraulic motor circuit, respectively. One end of the first hydraulic motor circuit is connected to the first differential pressure reducing valve through the second solenoid directional valve. The other end of the first hydraulic motor circuit is grounded through the second solenoid directional valve. One end of the second hydraulic motor circuit is connected to the first differential pressure reducing valve through the third solenoid directional valve. The other end of the second hydraulic motor circuit is grounded through the third solenoid directional valve.

[0014] A first shuttle valve is connected between one end of the first hydraulic motor circuit and one end of the second hydraulic motor circuit. A second shuttle valve is connected between the other end of the first hydraulic motor circuit and the other end of the second hydraulic motor circuit. One end of the first shuttle valve is connected to one end of the fourth shuttle valve, and one end of the second shuttle valve is connected to one end of the third shuttle valve.

[0015] As a further preferred embodiment of the present invention,

[0016] The cutting platform lifting hydraulic system includes three cutting platform single-acting hydraulic cylinders. Each cutting platform single-acting hydraulic cylinder is simultaneously connected to a flow distribution pump and a one-way throttle valve to form a cutting platform circuit. One end of each cutting platform circuit is simultaneously connected to the second differential pressure reducing valve through the fourth solenoid directional valve. The other end of each cutting platform circuit is simultaneously connected to the oil tank through the fourth solenoid directional valve.

[0017] One end of each cutter circuit is simultaneously connected to the other end of the fourth shuttle valve, and the other end of each cutter circuit is simultaneously connected to the other end of the third shuttle valve.

[0018] The first differential pressure reducing valve is connected to the fifth shuttle valve, the second differential pressure reducing valve is connected to the sixth shuttle valve, the fifth and sixth shuttle valves are simultaneously connected to the fourth shuttle valve, and the fifth and sixth shuttle valves are simultaneously connected to the third shuttle valve.

[0019] As a further preferred embodiment of the present invention, the fifth shuttle valve and the sixth shuttle valve are connected to form a pressure compensation circuit.

[0020] Based on the control method of the hydraulic control system for the leafy vegetable harvester,

[0021] After the system starts, the oil in the tank flows from the two hydraulic motors into the second, third, and fourth solenoid directional valves. The second and third solenoid directional valves control the corresponding hydraulic motor circuits, and the fourth solenoid directional valve controls the corresponding header circuit. The pressure compensation circuit meets the flow distribution requirements of the hydraulic motor circuit and the header circuit, so that the forward and backward movement of the leafy vegetable harvester and the harvesting of leafy vegetables can work simultaneously.

[0022] As a further preferred embodiment of the present invention, the pressure compensation circuit operates as follows:

[0023] Step S1: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors rotate forward and the three single-acting hydraulic cylinders of the cutting table rise;

[0024] The first shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the second shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit.

[0025] Step S2: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors reverse and the three single-acting hydraulic cylinders of the cutter head descend;

[0026] The second shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the first shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit.

[0027] Step S3: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors rotate forward and the three single-acting hydraulic cylinders of the cutting table descend;

[0028] The first shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the second shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit.

[0029] Step S4: The highest inlet pressure or the highest return pressure selected by the third shuttle valve or the fourth shuttle valve in steps S1-S3 is respectively led to the fifth shuttle valve or the sixth shuttle valve in the pressure compensation circuit. The pressure compensation circuit selects the highest load pressure and leads the highest load pressure to the matching first differential pressure reducing valve and second differential pressure reducing valve. The first differential pressure reducing valve and the second differential pressure reducing valve keep the inlet and outlet pressure difference of the first solenoid directional valve, the second solenoid directional valve, the third solenoid directional valve and the fourth solenoid directional valve at a constant positive value.

[0030] By employing the above technical solutions, the present invention has the following beneficial effects compared to the prior art:

[0031] 1. The hydraulic control system for a leafy vegetable harvester provided by the present invention enables the leafy vegetable harvester to move forward and backward via a rear-wheel drive hydraulic system. The hydraulic motor can adapt to complex outdoor planting ground environments, and has strong driving force, low energy consumption, low emissions, and fast system response.

[0032] 2. The hydraulic control system for a leafy vegetable harvester provided by the present invention includes a buffer braking circuit consisting of two check valves and two relief valves connected in parallel in the rear wheel drive hydraulic system. When the circuit pressure exceeds the working pressure of the relief valve, the relief valve starts the relief operation, and at the same time, oil is replenished to the other side through the check valve, thereby reducing hydraulic shock.

[0033] 3. The hydraulic control system for leafy vegetable harvesters provided by this invention enables the header lifting hydraulic system to lift and lower synchronously, allowing the header to adapt to complex ground conditions and make timely steering adjustments to uneven road surfaces.

[0034] 4. The hydraulic control system for leafy vegetable harvesters provided by this invention has a pressure compensation circuit that ensures that the pressure of the hydraulic motor circuit and the header circuit always meets the load requirements, avoiding uneven flow distribution in the hydraulic motor circuit and the header circuit due to different external loads, thereby ensuring that the header and the rear wheel can work simultaneously without affecting each other. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0036] Figure 1 This is a schematic diagram of the hydraulic control system for a leafy vegetable harvester provided by the present invention.

[0037] In the diagram: 101 is the first differential pressure reducing valve, 102 is the second differential pressure reducing valve, 21 is the first solenoid directional valve, 22 is the second solenoid directional valve, 23 is the third solenoid directional valve, 24 is the fourth solenoid directional valve, 31 is the first shuttle valve, 32 is the second shuttle valve, 33 is the third shuttle valve, 34 is the fourth shuttle valve, 35 is the fifth shuttle valve, 36 is the sixth shuttle valve, 4 is the steering double-acting hydraulic cylinder, 5 is the hydraulic motor, 6 is the check valve, 7 is the flow distribution pump, 8 is the cutting table single-acting hydraulic cylinder, 9 is the one-way throttle valve, 10 is the relief valve, 11 is the hydraulic pump, and 12 is the oil tank. Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings. In the description of this application, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of the present invention.

[0039] As described in the background section, the operation of various components in existing leafy vegetable harvesters is mostly achieved through electric and mechanical transmission. This results in complex operation, inconvenient operation, difficulty in repair when malfunctions occur, and an inability to maintain a long operating time.

[0040] To address the aforementioned issues, this application provides a hydraulic control system for a leafy vegetable harvester, which involves the operation of three components: the steering of the front wheels, the driving of the rear wheels, and the harvesting operation of the header. The operation of these three components is optimized to a hydraulic transmission method. Furthermore, this application provides an integrated hydraulic system that maintains a stable transmission process during leafy vegetable harvesting. The simple operating structure and matching operating method reduce the labor intensity of operators.

[0041] Specifically, such as Figure 1 As shown, this application includes a front-wheel steering hydraulic system, a rear-wheel drive hydraulic system, and a header lifting hydraulic system. These three hydraulic systems are connected to each other via an overflow valve 10 and an oil tank 12, and are also connected to the oil tank via a hydraulic pump 11. Of the three parts, the front-wheel steering hydraulic system enables the front wheels of the leafy vegetable harvester to steer, the rear-wheel drive hydraulic system enables the leafy vegetable harvester to move forward and backward, and the header lifting hydraulic system enables the leafy vegetable harvester to start harvesting.

[0042] First is the front wheel steering hydraulic system, which includes a double-acting steering lever hydraulic cylinder 4 and a first solenoid directional valve 21. The telescopic end of the double-acting steering lever hydraulic cylinder is connected to the front wheel, the fixed end of the double-acting steering lever hydraulic cylinder is connected to one end of the first solenoid directional valve, and the other end of the first solenoid directional valve is connected to the relief valve and the hydraulic pump.

[0043] The principle of controlling front wheel steering through the front wheel steering hydraulic system is as follows: the oil circuit passes through the first solenoid directional valve, with oil entering its P chamber. Under the operator's control, the oil route goes from the P chamber to the A chamber, then to the double-acting steering rod hydraulic cylinder, and from the B chamber of the double-acting steering rod hydraulic cylinder to the T return oil chamber, thus enabling the double-acting steering rod to work to the right and achieve right turn. Under the operator's control, the oil route goes from the P chamber to the B chamber, then to the steering cylinder, and from the A chamber of the double-acting steering rod hydraulic cylinder to the T return oil chamber, thus enabling the double-acting steering rod of the double-acting steering rod hydraulic cylinder to work to the left and achieve left turn.

[0044] Next is the rear-wheel drive hydraulic system, which includes two hydraulic motors 5, a first shuttle valve 31, a second shuttle valve 32, a third shuttle valve 33, a fourth shuttle valve 34, a second solenoid directional valve 22, and a third solenoid directional valve 23. Two check valves 6 and two relief valves are connected in parallel to form a buffer braking circuit. Each hydraulic motor is connected to a buffer braking circuit to form a hydraulic motor circuit. The two hydraulic motor circuits are defined as the first hydraulic motor circuit and the second hydraulic motor circuit, respectively. One end of the first hydraulic motor circuit is connected to the first differential pressure reducing valve 101 through the second solenoid directional valve, and the other end of the first hydraulic motor circuit is grounded through the second solenoid directional valve. One end of the second hydraulic motor circuit is connected to the first differential pressure reducing valve through the third solenoid directional valve, and the other end of the second hydraulic motor circuit is grounded through the third solenoid directional valve. The first shuttle valve is connected between one end of the first hydraulic motor circuit and one end of the second hydraulic motor circuit, and the second shuttle valve is connected between the other end of the first hydraulic motor circuit and the other end of the second hydraulic motor circuit. The first shuttle valve is connected to one end of the fourth shuttle valve, and the second shuttle valve is connected to one end of the third shuttle valve.

[0045] In the rear-wheel drive hydraulic system, the forward and reverse movements of the leafy vegetable harvester are achieved by the forward and reverse rotation of two hydraulic motors. Specifically, when both hydraulic motors rotate forward simultaneously, both rear wheels rotate forward, and the leafy vegetable harvester travels forward in a straight line. When both hydraulic motors rotate in reverse simultaneously, both rear wheels rotate in reverse, and the leafy vegetable harvester travels backward in a straight line. Figure 1Taking a medium-angle view as an example, two hydraulic motors are located on the left and right sides. The principle for controlling the forward rotation of the hydraulic motors is as follows: the oil in the tank is pumped to either the second or third solenoid directional valve. When either the second or third solenoid directional valve is in the left position, the oil flows from port P to port A, through the pipeline to the hydraulic motor, and then from port B to port T back to the tank, at which point the hydraulic motor rotates forward. The principle for controlling the reverse rotation of the hydraulic motors is as follows: the oil in the tank is pumped to either the second or third solenoid directional valve. When either the second or third solenoid directional valve is in the right position, the oil flows from port P to port B, through the pipeline to the hydraulic motor, and then from port A to port T back to the tank, at which point the hydraulic motor rotates in reverse.

[0046] Each hydraulic motor is matched with two check valves and two relief valves connected in parallel to form a buffer braking circuit. To reduce hydraulic shock, when the hydraulic motor circuit pressure exceeds the relief valve's working pressure, the relief valve begins to overflow and replenishes oil to the other side through the check valve. One of the innovations of this application is that the two hydraulic motors can achieve synchronized speeds because the two hydraulic motors detect their speeds using speed sensors, feeding the signals back to the second and third solenoid directional valves. The second or third solenoid directional valve controls the hydraulic motor flow rate by opening and closing, thereby controlling the hydraulic motor speed and enabling the two hydraulic motors to achieve synchronized speeds.

[0047] The cutting platform lifting hydraulic system provided in this application includes three cutting platform single-acting hydraulic cylinders 8. Each cutting platform single-acting hydraulic cylinder 8 is simultaneously connected to a flow distribution pump 7 and a one-way throttle valve 9 to form a cutting platform circuit. One end of each cutting platform circuit is simultaneously connected to the second differential pressure reducing valve 102 through the fourth solenoid directional valve 24, and the other end of each cutting platform circuit is simultaneously connected to the oil tank through the fourth solenoid directional valve. One end of each cutting platform circuit is simultaneously connected to the other end of the fourth shuttle valve, and the other end of each cutting platform circuit is simultaneously connected to the other end of the third shuttle valve. The first differential pressure reducing valve is connected to the fifth shuttle valve 35, the second differential pressure reducing valve is connected to the sixth shuttle valve 36, the fifth shuttle valve and the sixth shuttle valve are simultaneously connected to the fourth shuttle valve, and the fifth shuttle valve and the sixth shuttle valve are simultaneously connected to the third shuttle valve.

[0048] When the leafy vegetable harvester is operating the header, the header lifting hydraulic system provided in this application can achieve synchronous raising or lowering of the header. Specifically, when it is necessary to control the synchronous lifting of the cutting conveyor, when the fifth solenoid directional valve is energized and in the left position, the oil route enters from P to A, and the hydraulic oil enters the flow distribution pump. After the flow distribution pump, the hydraulic oil is evenly distributed to the rodless chambers of the three single-acting hydraulic cylinders of the header. The hydraulic oil in the rod chamber of the single-acting hydraulic cylinder of the header returns to B through the one-way throttle valve and then enters the oil tank through T. At this time, the single-acting hydraulic cylinder of the header achieves the extension action, thereby controlling the header lifting function. When the fifth solenoid directional valve is de-energized and returns to the neutral position, the oil flows directly back to the oil tank. At this time, the three single-acting hydraulic cylinders of the header achieve pressure holding and maintain the current position. When the cutting conveyor needs to be lowered synchronously, the fifth solenoid directional valve is energized and in the right position. The oil route enters from P to B, and the hydraulic oil enters the one-way throttle valve. After passing through the one-way valve, the hydraulic oil is evenly distributed to the rodless chambers of the three single-acting hydraulic cylinders of the cutting table. The hydraulic oil in the rod chamber of the single-acting hydraulic cylinder returns to A through the one-way throttle valve and then enters the oil tank at T. At this time, the single-acting hydraulic cylinder of the cutting table achieves the extension action, thereby controlling the lowering function of the cutting table. When the fifth solenoid directional valve is de-energized and returns to the neutral position, the oil flows directly back to the oil tank. At this time, the three single-acting hydraulic cylinders of the cutting table achieve pressure holding and maintain the current position.

[0049] In summary, the hydraulic control system for a leafy vegetable harvester provided in this application has the following control method: After the system starts, the oil in the tank flows from the two hydraulic motors into the second, third, and fourth solenoid directional valves; the second and third solenoid directional valves control the corresponding hydraulic motor circuits, and the fourth solenoid directional valve controls the corresponding header circuit. The most significant innovation of this application is that the fifth and sixth shuttle valves are connected to form a pressure compensation circuit within the entire control system. Through the use of the fifth and sixth shuttle valves, the first differential pressure reducing valve, and the second differential pressure reducing valve, the circuit pressure of the hydraulic motor circuit and the header circuit always meets the load requirements, preventing uneven flow distribution due to different external loads on the two circuits. This allows the header circuit and the hydraulic motor circuit to work simultaneously without interfering with each other.

[0050] The specific steps involved in the operation of the pressure compensation circuit are as follows:

[0051] Step S1: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors rotate forward and the three single-acting hydraulic cylinders of the cutting table rise;

[0052] The first shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the second shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit.

[0053] Step S2: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors reverse and the three single-acting hydraulic cylinders of the cutter head descend;

[0054] The second shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the first shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit.

[0055] Step S3: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors rotate forward and the three single-acting hydraulic cylinders of the cutting table descend;

[0056] The first shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the second shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit.

[0057] Step S4: The highest inlet pressure or the highest return pressure selected by the third or fourth shuttle valve in steps S1-S3 is respectively led to the fifth or sixth shuttle valve in the pressure compensation circuit. The pressure compensation circuit selects the highest load pressure and leads the highest load pressure to the matching first and second differential pressure reducing valves. The first and second differential pressure reducing valves keep the inlet and outlet pressure difference of the first, second, third, and fourth solenoid directional valves at a constant positive value. Oil flows into each circuit, regardless of the load pressure, so that the oil can meet the flow distribution requirements of the hydraulic motor circuit and the cutting table circuit in the system.

[0058] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0059] The meaning of "and / or" as used in this application includes situations where each exists alone or both exist simultaneously.

[0060] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0061] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A hydraulic control system for a leafy vegetable harvester, characterized in that: It includes a front wheel steering hydraulic system, a rear wheel drive hydraulic system, and a cutting platform lifting hydraulic system. The three hydraulic systems are connected to each other and connected to the oil tank through an overflow valve and a hydraulic pump. The front wheel steering hydraulic system enables the front wheels of the leafy vegetable harvester to steer, the rear wheel drive hydraulic system enables the leafy vegetable harvester to move forward and backward, and the header lifting hydraulic system enables the leafy vegetable harvester to start harvesting. The front wheel steering hydraulic system includes a double-acting steering lever hydraulic cylinder and a first solenoid directional valve. The telescopic end of the double-acting steering lever hydraulic cylinder is connected to the front wheel, the fixed end of the double-acting steering lever hydraulic cylinder is connected to one end of the first solenoid directional valve, and the other end of the first solenoid directional valve is connected to both the relief valve and the hydraulic pump. The rear-wheel drive hydraulic system includes two hydraulic motors, a first shuttle valve, a second shuttle valve, a third shuttle valve, a fourth shuttle valve, a second solenoid directional valve, and a third solenoid directional valve. Two check valves and two relief valves are connected in parallel to form a buffer braking circuit. Each hydraulic motor is connected to a buffer braking circuit to form a hydraulic motor circuit. The two hydraulic motor circuits are defined as the first hydraulic motor circuit and the second hydraulic motor circuit, respectively. One end of the first hydraulic motor circuit is connected to the first differential pressure reducing valve through the second solenoid directional valve, and the other end of the first hydraulic motor circuit is grounded through the second solenoid directional valve. One end of the second hydraulic motor circuit is connected to the first differential pressure reducing valve through the third solenoid directional valve, and the other end of the second hydraulic motor circuit is grounded through the third solenoid directional valve. The first shuttle valve is connected between one end of the first hydraulic motor circuit and one end of the second hydraulic motor circuit, and the second shuttle valve is connected between the other end of the first hydraulic motor circuit and the other end of the second hydraulic motor circuit. The first shuttle valve is connected to one end of the fourth shuttle valve, and the second shuttle valve is connected to one end of the third shuttle valve. The cutting platform lifting hydraulic system includes three single-acting hydraulic cylinders. Each single-acting hydraulic cylinder is simultaneously connected to a flow distribution pump and a one-way throttle valve to form a cutting platform circuit. One end of each cutting platform circuit is simultaneously connected to the second differential pressure reducing valve through a fourth solenoid directional valve, and the other end of each cutting platform circuit is simultaneously connected to the oil tank through the fourth solenoid directional valve. One end of each cutting platform circuit is simultaneously connected to the other end of the fourth shuttle valve, and the other end of each cutting platform circuit is simultaneously connected to the other end of the third shuttle valve. The first differential pressure reducing valve is connected to the fifth shuttle valve, the second differential pressure reducing valve is connected to the sixth shuttle valve, the fifth and sixth shuttle valves are simultaneously connected to the fourth shuttle valve, and the fifth and sixth shuttle valves are simultaneously connected to the third shuttle valve.

2. The hydraulic control system for a leafy vegetable harvester according to claim 1, characterized in that: The fifth shuttle valve and the sixth shuttle valve are connected to form a pressure compensation circuit.

3. The control method for the hydraulic control system of a leafy vegetable harvester according to claim 2, characterized in that: After the system starts, the oil in the tank flows from the two hydraulic motors into the second, third, and fourth solenoid directional valves. The second and third solenoid directional valves control the corresponding hydraulic motor circuits, and the fourth solenoid directional valve controls the corresponding header circuit. The pressure compensation circuit meets the flow distribution requirements of the hydraulic motor circuit and the header circuit, so that the forward and backward movement of the leafy vegetable harvester and the harvesting of leafy vegetables can work simultaneously.

4. The control method for the hydraulic control system of a leafy vegetable harvester according to claim 3, characterized in that: The pressure compensation circuit operates as follows: Step S1: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors rotate forward and the three single-acting hydraulic cylinders of the cutting table rise; The first shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the second shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit. Step S2: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors reverse and the three single-acting hydraulic cylinders of the cutter head descend; The second shuttle valve selects the highest inlet pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest inlet pressure of the hydraulic motor circuit and the cutter table circuit; the first shuttle valve selects the highest return pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest return pressure of the hydraulic motor circuit and the cutter table circuit. Step S3: Select the highest inlet oil pressure and the highest return oil pressure when the two hydraulic motors rotate forward and the three single-acting hydraulic cylinders of the cutter head descend; the first shuttle valve selects the highest inlet oil pressure of the two hydraulic motor circuits, and the fourth shuttle valve filters out the highest inlet oil pressure in the hydraulic motor circuit and the cutter head circuit; the second shuttle valve selects the highest return oil pressure of the two hydraulic motor circuits, and the third shuttle valve filters out the highest return oil pressure in the hydraulic motor circuit and the cutter head circuit. Step S4: The highest inlet pressure or the highest return pressure selected by the third shuttle valve or the fourth shuttle valve in steps S1-S3 is respectively led to the fifth shuttle valve or the sixth shuttle valve in the pressure compensation circuit. The pressure compensation circuit selects the highest load pressure and leads the highest load pressure to the matching first differential pressure reducing valve and second differential pressure reducing valve. The first differential pressure reducing valve and the second differential pressure reducing valve keep the inlet and outlet pressure difference of the first solenoid directional valve, the second solenoid directional valve, the third solenoid directional valve and the fourth solenoid directional valve at a constant positive value.

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