Tractor rear suspension hydraulic system and control method

Abstract

A rear suspension hydraulic system of a tractor comprises an ascending proportional electromagnetic valve, a descending proportional electromagnetic valve and a one-way valve which are connected with a rodless cavity of a lifting oil cylinder and used for controlling ascending and descending of a machine tool. Comprising a two-position two-way electromagnetic directional valve, a throttling valve and a two-position three-way electromagnetic valve, and an overflow valve is connected with a rod cavity of the lifting oil cylinder and used for controlling the high pressure of a machine tool to be reduced; comprising a three-position four-way electromagnetic valve which is connected with the second oil cylinder and used for controlling overturning of the machine tool. By means of the hydraulic system, ascending, descending, floating, high-pressure descending, ascending and overturning linkage of the machine tool can be achieved, and the speed of the machine tool in the ascending and descending process is adjustable.

Description

Technical Field

[0001] This invention belongs to the field of electro-hydraulic control, specifically relating to a hydraulic system and control method for the rear suspension of a tractor. Background Technology

[0002] The tractor lifting system mainly consists of a control panel, controller, lifting control valve, angle sensor, force sensor, and ground-based radar for slippage control. Its main functions include force control, position control, combined force-position control, floating control, height limiting, tillage depth control, and active damping. The main control logic involves the controller, based on instructions from the control panel and feedback from the position sensors, controlling the lifting height and tillage depth of the three-point suspension in real time. The combined force-position control integrates traction force and tillage depth control, fully utilizing the tractor's traction power while ensuring more uniform tillage depth and guaranteeing tillage quality.

[0003] Currently, domestic tractor lifting systems are mainly mechanical, using mechanical levers or flexible shafts to control the displacement of a multi-way valve core, thereby controlling the lifting and lowering of the tractor implements. In practical applications, when the implement is raised to its highest point using the multi-way valve, the implement will vibrate and fall back due to the nature of the valve, resulting in a poor user experience when lifting the implement during tractor turns. With the development of farm operations, younger operators, and the trend towards intelligent operations, the market demand for electro-hydraulic lifting systems is increasing; at the same time, electro-hydraulic lifting is a necessary module for future intelligent integration. Summary of the Invention

[0004] This invention employs an electro-hydraulic proportional valve, combined with a control system. By adjusting the lifting and lowering speed adjustment knobs, the energizing current of the proportional control valve is adjusted, thereby regulating the lifting and lowering speeds and making the machine more stable during lifting and lowering. At the same time, the control system enables the linkage between the lifting and tilting of the machine, further reducing labor intensity.

[0005] In a first aspect, the present invention provides a tractor rear suspension electronic control system, including an operation panel, a controller, a lifting arm angle sensor, a lifting cylinder, a proportional solenoid valve assembly, and a high-pressure coupling. The operation panel includes a tillage depth adjustment knob, a lifting height limit knob, a one-button lifting and flipping function key, a lowering function key, and a speed adjustment knob. The operation panel is connected to the controller input terminal via a CAN bus. The lifting arm angle sensor is installed on the lifting arm and connected to the controller input terminal to detect the angle information of the lifting arm and transmit the angle information to the controller. The controller calculates the height of the lifting arm from the ground. The proportional solenoid valve assembly and the high-pressure coupling are electrically connected to the controller and connected to the hydraulic pipe of the lifting cylinder to control the raising and lowering of the lifting arm and the high-pressure lowering, thereby driving the lifting and lowering of the implement.

[0006] Furthermore, the tractor's rear suspension electronic control system also includes a second solenoid valve and a second hydraulic cylinder. The second solenoid valve is connected to the controller and to the second hydraulic cylinder via an oil pipe. The piston rod of the second hydraulic cylinder is connected to the reversible plow. The second solenoid valve is used to control the extension and retraction of the second hydraulic cylinder, thereby driving the plow to reverse.

[0007] Secondly, a tractor rear suspension hydraulic system includes: a proportional solenoid valve assembly and a high-pressure coupling; the proportional solenoid valve assembly includes an inlet flow control valve connected to an inlet P and a return flow control valve connected to a return port R1; a check valve is connected between the inlet flow control valve and the return flow control valve; the check valve and the return flow control valve are respectively connected to the rodless chamber of the lifting cylinder; the proportional solenoid valve assembly is used to control the raising and lowering of the lifting rod. The high-pressure connection includes: a two-position two-way solenoid valve connected between the oil inlet P and the oil inlet flow control valve; a throttle valve connected between the oil inlet P and the two-position two-way solenoid valve; a two-position three-way solenoid valve connected to the throttle valve; the output end of the two-position three-way solenoid valve is connected to the rod chamber of the lifting cylinder; the high-pressure connection controls the high-pressure descent of the lifting rod. A first relief valve is connected between the oil inlet P and the oil return port T, and a second relief valve is connected between the output end of the two-position three-way solenoid valve and the oil return port. The relief valve is used to limit the maximum pressure of the oil circuit port.

[0008] Furthermore, the tractor's rear suspension hydraulic system also includes a tilting linkage, which includes a three-position four-way solenoid valve connected to the oil inlet P. The three-position four-way solenoid valve is connected to the second oil cylinder to control the implement to tilt left and right.

[0009] Furthermore, a pressure compensation valve is connected between the return port T and the inlet flow control valve to maintain stable system pressure.

[0010] Thirdly, based on the aforementioned tractor rear suspension electro-hydraulic control system, its control methods include: Lifting the implement: When the inlet flow solenoid valve is energized, hydraulic oil flows from port P to the inlet flow control valve. The check valve opens, and the hydraulic oil enters the rodless chamber of the lifting cylinder. Adjusting the speed adjustment knob changes the displacement of the valve core of the inlet flow control valve and the flow rate, thus changing the lifting speed of the lifting rod. The lifting speed of the implement is adjustable. When the implement is lowered: the return flow solenoid valve is energized, the check valve is closed, and the hydraulic oil flows from the rodless chamber through the return flow solenoid valve to the return oil tank R1. Adjusting the speed adjustment knob changes the displacement of the return flow control valve core and the flow rate, thus changing the lowering speed of the lifting rod. The lowering speed of the implement is adjustable.

[0011] Strong pressure reduction: When the return flow solenoid valve is energized, the two-position three-way solenoid valve ③ is energized, and the two-position two-way solenoid valve ⑥ is energized and closed in the normally open state, the hydraulic oil seal is closed. The hydraulic oil flows through port P to the throttle valve ② and the two-position three-way solenoid valve ③ to the rod chamber of the lifting cylinder. The hydraulic oil in the rodless chamber returns to the oil tank R1 through the return flow solenoid valve. Similarly, the strong pressure reduction speed is adjustable.

[0012] Lifting and tilting linkage: When the oil inlet flow solenoid valve is energized, hydraulic oil flows through port P to the oil inlet flow control valve. The check valve opens, and hydraulic oil enters the rodless chamber of the lifting cylinder. The lifting rod drives the machine to rise to the specified height. When the oil inlet flow solenoid valve is de-energized, the three-position four-way solenoid valve ⑨ is energized in the left (or right) position, and the two-position two-way solenoid valve ⑥ is energized and closed in the normally open state. The hydraulic oil enters the second oil cylinder through port P, and the extension and retraction of the second oil cylinder drives the machine to flip to the left (or right). Attached Figure Description

[0013] Figure 1 This is a schematic diagram of an embodiment of the electronic control system for the rear suspension of a tractor. Figure 2 This is a schematic diagram of an embodiment of the hydraulic system for the rear suspension of a tractor. Detailed Implementation

[0014] To make the technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention. Based on the described embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance; they are merely used to distinguish the relationship between multiple identical elements and other different elements. The terms "installed," "connected," and "linked" in this invention should be interpreted broadly.

[0016] Combination Figure 1A tractor rear suspension electronic control system includes an operation panel, a controller, a lifting arm angle sensor, a lifting cylinder, a proportional solenoid valve assembly, a pressure coupling, a second solenoid valve, and a second cylinder. The operation panel includes a tillage depth adjustment knob, a lifting height limit knob, a one-button lifting and flipping function key, a lowering function key, and a speed adjustment knob. The operation panel is connected to the controller input terminal via a CAN bus. The lifting arm angle sensor, installed on the lifting arm and connected to the controller input terminal, is used to detect the angle information of the lifting arm and transmit the angle information to the controller. The controller calculates the height of the lifting arm from the ground. The proportional solenoid valve assembly and the pressure coupling, connected to the controller and connected to the lifting cylinder via oil pipes, are used to control the raising and lowering of the lifting arm and the pressure lowering, thereby driving the lifting and lowering of the implement. During the raising and lowering of the implement, adjusting the speed adjustment knob, the proportional solenoid current changes, the valve core displacement changes, and the flow rate changes, making the moving speed of the implement adjustable.

[0017] The tractor's rear suspension hydraulic system also includes a tilting linkage, which includes a second solenoid valve. The second solenoid valve is a three-position four-way solenoid valve, connected to the controller and connected to the second cylinder via an oil pipe. The piston rod of the second cylinder is connected to the implement. The second solenoid valve is used to control the extension and retraction of the second cylinder, thereby driving the implement to tilt.

[0018] When the tractor turns at the edge of the field, the one-button lift and tilt function is activated. Once activated, this function is enabled, and the controller controls the proportional solenoid valve group to operate. The lifter immediately raises the plow, and the angle sensor on the lifting arm transmits the angle information to the controller in real time. When the plow is raised to the position set by the height limit knob, the controller controls the second solenoid valve to operate for a duration of b, and the second cylinder extends and retracts, causing the plow to tilt 180°. When the driver turns around and performs the plow lowering action, the lowering function key is activated. Once activated, this function is enabled, and the controller controls the proportional solenoid valve group to operate. The lifter lowers the plow, and when the plow reaches the ground, the controller activates the high-pressure function. The high-pressure solenoid valve operates, and the lifting cylinder forces the plow into the soil with high pressure. At the same time, the angle sensor on the lifting arm transmits the angle information to the controller in real time, controlling the plow to lower to the position set by the tillage depth adjustment knob, ensuring consistent tillage.

[0019] Combination Figure 2The tractor rear suspension hydraulic system includes an inlet flow control valve connected to the inlet port P, an inlet flow solenoid valve output connected to a check valve, and the check valve output connected to the rodless chamber of the lifting cylinder; and a return flow control valve, the output of which is connected to the return port R1, and the other end connected between the check valve output and the rodless chamber of the lifting cylinder; the check valve is connected between the inlet flow control valve and the return flow control valve, opening when oil enters the rodless chamber and closing one-way when oil exits the rodless chamber, making the inlet and return flow logic of the lifting cylinder controllable; the inlet flow control valve and the return flow control valve are respectively connected to the rodless chamber of the lifting cylinder to control the raising and lowering of the lifting rod.

[0020] The inlet flow control valve and the return flow control valve are electromagnetic proportional directional valves. During the lifting and lowering of the machine, the energizing current of the proportional electromagnets DT2 and DT1 is adjusted by adjusting the lifting and lowering speed adjustment knobs. The larger the power supply current of the electromagnets, the greater the valve core displacement and the larger the flow surface of the proportional valve.

[0021] A two-position normally open solenoid directional valve ⑥ is connected between the oil inlet P and the oil inlet flow control valve. A throttle valve ② is connected between the oil inlet P and the two-position normally open solenoid directional valve ⑥. The throttle valve ② is connected to a two-position three-way solenoid directional valve ③. The output end of the two-position three-way solenoid directional valve ③ is connected to the rod chamber of the lifting cylinder. The strong pressure control of the lifting rod leads to a strong pressure drop.

[0022] The oil inlet P is connected to the three-position four-way solenoid valve ⑨, which is connected to the second oil cylinder. The extension and retraction of the second oil cylinder causes the plow to flip left and right. When the electromagnets DT3 and DT5 are energized, the two-position two-way solenoid valve ⑥ changes from normally open to closed, the hydraulic oil is blocked, oil is discharged from end A2 and oil is returned from end B2, the oil cylinder extends and retracts, and the plow flips to the left. When the electromagnets DT3 and DT6 are energized, oil is returned from end A2 and oil is discharged from end B2, the oil cylinder extends and retracts, and the plow flips to the right.

[0023] A first relief valve ① is connected between the oil inlet P and the oil return port T, with a working pressure of 20MPa, to prevent the total pressure at the oil outlet P from being too high and to maintain system stability. A second relief valve ④ is connected between the output end of the two-position three-way solenoid valve ③ and the oil return port, with a working pressure of 3MPa. When the pressure exceeds the set value during the strong pressure drop, the second relief valve opens, and the excess oil flows back to port T to prevent the pressure from being too high during the strong pressure drop and to maintain stable pressure.

[0024] In one embodiment, a pressure compensation valve is connected between the return port T and the inlet flow control valve to keep the pressure in the lifting circuit constant during the lifting process, so that the machine rises smoothly.

[0025] Thirdly, based on the aforementioned electro-hydraulic control system, the control method for the tractor's rear suspension hydraulic system includes: Lifting the implement: When the proportional electromagnet DT2 is energized, the two-position two-way solenoid valve ⑥ is normally open. Hydraulic oil flows from port P to the pressure compensation valve, causing the valve core to move downward. This adjusts and corrects the flow rate in the lifting circuit, stabilizing the oil flow through the inlet flow solenoid valve. The hydraulic oil then enters the inlet flow control valve, opening the check valve and allowing the hydraulic oil to enter the rodless chamber of the lifting cylinder. The lifting rod moves upward, and the lifter drives the implement to rise. During the lifting process, the lifting speed can be adjusted by changing the lifting speed knob, making the lifting speed of the implement adjustable.

[0026] When the implement descends, the proportional electromagnet DT1 is energized, the check valve is shut off, and the hydraulic oil flows from the rodless chamber through the return flow solenoid valve to the return oil tank R1. The lifting rod descends, and the lifting device drives the implement to descend. During the descent, the speed of the lifting rod can be changed by adjusting the descent speed adjustment knob. The descent speed of the implement is adjustable.

[0027] Forced pressure descent: Proportional electromagnet DT1 is energized, 2-position 3-way solenoid valve ③ is energized, and 2-position 2-way solenoid valve ⑥ is energized, closing the hydraulic oil seal in its normally open state. Hydraulic oil flows through port P to throttle valve ②, 2-position 3-way solenoid valve ③, and then to the rod chamber of the lifting cylinder. Hydraulic oil in the rodless chamber returns to the oil tank R1 via the return flow solenoid valve. The implement descends to the value set by the tillage depth knob, ensuring consistent tillage depth. During forced pressure descent, the descent speed adjustment knob is used to change the implement's descent speed. Simultaneously, the second relief valve ④ ensures that the maximum pressure at the output of 2-position 3-way solenoid valve ③ is 3MPa, maintaining stable circuit pressure.

[0028] Lifting and Tilting Linkage: When the proportional electromagnet DT2 is energized, hydraulic oil flows through port P to the inlet flow control valve. The check valve opens, and hydraulic oil enters the rodless chamber of the lifting cylinder. The lifting rod rises, and the lifting device drives the machine to rise to the specified height. When the proportional electromagnet DT2 is de-energized, the two-position two-way solenoid valve ⑥ is energized and closed from its normally open state. The three-position four-way solenoid valve ⑨ is energized from its left position DT5 (or right position DT6). Hydraulic oil enters the second cylinder through port P. The extension and retraction of the second cylinder drives the tilting plow to tilt to the left (or right), realizing the linkage between lifting and tilting of the implement, further reducing labor intensity.

[0029] The above electro-hydraulic control system can realize the functions of lifting, neutralizing, lowering, floating, lifting and tilting linkage, and adjustable lowering speed of the tractor's rear suspension implements. When using it, the number of hydraulic outputs to use depends on the number of hydraulic output points required by the implements matched with the tractor. The lifting and tilting linkage can be selected for the reversible plow.

Claims

1. A hydraulic system for the rear suspension of a tractor, comprising a proportional solenoid valve assembly and a high-pressure coupling, characterized in that, The proportional solenoid valve assembly includes an inlet flow control valve connected to the inlet P and a return flow control valve connected to the return port R1; a check valve is connected between the inlet flow control valve and the return flow control valve, and the check valve and the return flow control valve are respectively connected to the rodless chamber of the lifting cylinder; the proportional solenoid valve assembly is used to control the rising and falling of the lifting rod. The high-pressure connection includes: a two-position two-way solenoid valve connected between the oil inlet P and the oil inlet flow control valve; a throttle valve connected between the oil inlet P and the two-position two-way solenoid valve; a two-position three-way solenoid valve connected to the throttle valve; the output end of the two-position three-way solenoid valve is connected to the rod chamber of the lifting cylinder; the high-pressure connection controls the high-pressure descent of the lifting rod. A first overflow valve is connected between the oil inlet P and the oil return port T, and a second overflow valve is connected between the output end of the two-position three-way solenoid valve and the oil return port. The overflow valve is used to limit the maximum pressure of the oil circuit port.

2. The tractor rear suspension hydraulic system according to claim 1, characterized in that, A pressure compensation valve is connected between the return port T and the inlet flow control valve to maintain stable system pressure.

3. The tractor rear suspension hydraulic system according to claim 1, characterized in that, It also includes a tilting linkage, which includes a three-position four-way solenoid valve connected to the oil inlet P. The three-position four-way solenoid valve is connected to the second oil cylinder to control the machine to tilt left and right.

4. A control method for a tractor rear suspension hydraulic system, based on the hydraulic system described in any one of claims 1-2, wherein the control method comprises: Lifting the implement: When the inlet flow solenoid valve is energized, hydraulic oil flows from port P to the inlet flow control valve. The check valve opens, and the hydraulic oil enters the rodless chamber of the lifting cylinder. Adjusting the flow adjustment knob changes the lifting speed of the lifting rod, and the lifting speed of the implement is adjustable. When the implement is lowered: the return oil flow solenoid valve is energized, the check valve is closed, and the hydraulic oil flows from the rodless chamber through the return oil flow solenoid valve to the return oil tank R1. Adjusting the flow adjustment knob changes the lifting speed of the lifting rod, and the lifting speed of the implement is adjustable.

5. A control method for a tractor rear suspension hydraulic system, based on the hydraulic system described in any one of claims 1-2, wherein the control method comprises: High pressure drop: The return flow solenoid valve is energized, the two-position three-way solenoid valve ③ is energized, and the two-position two-way solenoid valve ⑥ is energized and closed in the normally open state. The hydraulic oil flows through port P to the throttle valve ② and the solenoid directional valve ③ to the rod chamber of the lifting cylinder. The hydraulic oil in the rodless chamber returns to the oil tank R1 through the return flow solenoid valve.

6. A control method for a tractor rear suspension hydraulic system, based on the hydraulic system described in claim 3, wherein the control method comprises: Lifting and tilting linkage: When the oil inlet flow solenoid valve is energized, hydraulic oil flows through port P to the oil inlet flow control valve. The check valve opens, and hydraulic oil enters the rodless chamber of the lifting cylinder. The lifting rod drives the machine to rise to the specified height. When the inlet flow solenoid valve is de-energized, the three-position four-way solenoid valve ⑨ is energized in the left (or right) position, and the two-position two-way solenoid valve ⑥ is energized and closed in the normally open state to seal the hydraulic oil. The hydraulic oil enters the second cylinder through port P, and the extension and retraction of the second cylinder drives the machine to flip to the left (or right).

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