A tractor lift control valve, method, and tractor

Abstract

This invention provides a tractor lifter control valve, a method therein, and a tractor. The tractor lifter control valve includes: a pressure oil port, a cylinder port, a main control valve, a buffer valve, a lock-up check valve, and an unloading valve. The main control valve is connected to the pressure oil port, the lock-up check valve, and the unloading valve via pipelines. The buffer valve is connected to the pressure oil port, the lock-up check valve, and the unloading valve via pipelines. The lock-up check valve is connected to the cylinder port via a pipeline.

Description

Technical Field

[0001] This invention relates to the field of tractor lifting system technology, and more particularly to a tractor lifting control valve, method, and tractor. Background Technology

[0002] As a component of tractors, the lifter requires high intelligence, stability, efficiency, and low cost. Existing electronically controlled lifters typically use a controller to control an electronically controlled valve to achieve the reciprocating motion of a hydraulic cylinder, thus lifting, lowering, and holding the implement. However, existing electronically controlled lifters suffer from high cost and poor reliability. Mechanical force-position lifters, through a lift control valve and a mechanical force & position servo feedback mechanism, achieve integrated force and position control of the implement. They are reliable, simple in structure, and low in cost, making them an ideal operation control method. However, the core component of current force-position control lifters, the lift control valve, suffers from complex structure, poor operability, and low reliability. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a lifting device control valve, method, and tractor for a tractor.

[0004] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A tractor lifter control valve includes: a pressure oil interface, a cylinder interface, a main control valve, a buffer valve, a lock-up check valve, and an unloading valve. The main control valve is connected to the pressure oil interface, the lock-up check valve, and the unloading valve through pipelines. The buffer valve is connected to the pressure oil interface, the lock-up check valve, and the unloading valve through pipelines. The lock-up check valve is connected to the cylinder interface through a pipeline.

[0005] The beneficial effects of adopting the technical solution of this invention are that by controlling the return oil flow of the buffer valve core, load-sensitive and constant flow control functions are achieved, thus improving the operating performance of the lifter. Through closed-loop control of the main valve core and mechanical servo feedback mechanism, continuous automatic force and position control is achieved during operation. The four control valve modules work together to achieve the control functions of holding, lifting, and lowering. The structure is simple.

[0006] Furthermore, a throttling slot is provided on the pipeline between the unloading valve and the buffer valve.

[0007] The beneficial effect of adopting the above-mentioned further technical solutions is to improve handling performance.

[0008] Furthermore, the main control valve, the buffer valve, the lock-up check valve, and the unloading valve are all housed in the control valve housing, which is mounted on the lifter housing.

[0009] The advantages of adopting the above-mentioned further technical solution are that the built-in lock-up check valve can be directly installed on the lifting device housing without the need for pipeline connections, saving installation space. The lowering valve adopts a lock-up check valve structure, which can control the sinking amount of the lifting cylinder.

[0010] Furthermore, the control valve housing is provided with a first interface, a second interface, and a third interface. The first interface, the second interface, and the third interface are all connected to an oil tank through pipelines. The main control valve is connected to the first interface and the third interface through pipelines, and the unloading valve is connected to the second interface through a pipeline.

[0011] The beneficial effect of adopting the above-mentioned further technical solution is that the first interface, the second interface and the third interface are connected to the oil tank, which facilitates oil return.

[0012] Furthermore, the main control valve is a three-position six-way valve; the main control valve is provided with a main valve core, and the main valve core is provided with a flow groove.

[0013] The beneficial effect of adopting the above-mentioned further technical solution is that the main control valve adopts a three-position six-way structure and a throttling groove is set on the main valve core to improve the valve's control performance.

[0014] Furthermore, the pressure oil interface is connected to pressure oil output from a hydraulic pump via a pipeline; the cylinder interface is connected to a cylinder via a pipeline.

[0015] The beneficial effect of adopting the above-mentioned further technical solution is that the pressure oil output by the hydraulic pump is connected to the pressure oil interface, and the oil cylinder interface is connected to the lifting oil cylinder.

[0016] In addition, the present invention also provides a tractor including the aforementioned tractor lifter control valve.

[0017] In addition, the present invention also provides a control method for a tractor lifter. Based on the above-mentioned tractor lifter control valve, the tractor lifter control method includes: Holding condition: the main control valve is in the neutral position, the unloading valve is open to unload, the locking check valve is closed, and the cylinder is locked; Lifting condition: the main control valve is switched to the lifting position, the spring chamber of the unloading valve is closed by pressure oil, and the pressure oil from the pressure oil port passes through the main control valve and the locking check valve to the cylinder port, pushing the cylinder to lift; Lowering condition: the main control valve is switched to the lowering position, the unloading valve is opened to unload, the control oil on the upper side of the locking check valve is depressurized, the locking check valve is opened, and the load oil from the cylinder port returns to the oil tank through the locking check valve and the main control valve, causing the cylinder to lower; When switching between the holding condition, lifting condition, and lowering condition, a buffer valve buffers the pressure impact during the switching.

[0018] The beneficial effects of adopting the technical solution of this invention are that by controlling the return oil flow of the buffer valve core, load-sensitive and constant flow control functions are achieved, thus improving the operating performance of the lifter. Through closed-loop control of the main valve core and mechanical servo feedback mechanism, continuous automatic force and position control is achieved during operation. The four control valve modules work together to achieve the control functions of holding, lifting, and lowering. The structure is simple.

[0019] Furthermore, when switching between operating conditions, improving operating conditions, and decreasing operating conditions, the control performance of the main control valve is optimized through the throttling slot.

[0020] The beneficial effect of adopting the above-mentioned further technical solution is that the inlet pressure of the throttling slot acts on the lower non-spring chamber of the buffer valve, and the outlet pressure of the throttling slot acts on the upper spring chamber of the buffer valve. When the flow rate at port P increases, the return oil opening of the buffer valve increases, and the excess flow flows back to the oil tank from the buffer valve; conversely, the return oil opening decreases, and the return oil flow decreases. In this way, the flow rate of the throttling slot is linearly proportional to its own valve port area, achieving a smooth stop of the lifting action of the elevator. In addition, when the flow rate is saturated, the lifting flow rate can be controlled independently of the engine speed, thereby improving the stability of the elevator's lifting speed, and the control valve is in the lifting state at this time.

[0021] Further, maintaining the operating conditions: Pressure oil interface oil circuit: The pressure oil interface is closed through the main control valve oil circuit. The pressure oil acts on the non-spring side of the unloading valve, and after overcoming the spring resistance, the unloading valve opens. The pressure oil from the pressure oil interface returns to the oil tank through the second interface, and the hydraulic pump is in an unloaded state; Control oil circuit: The control oil in the unloading valve spring chamber returns to the oil tank through the middle position of the main control valve and the first interface, and the control oil is unloaded; Locking check valve: The load pressure oil from the cylinder interface reaches the upper spring chamber of the locking check valve through the oil passage of the middle position of the main control valve. The locking check valve closes, the cylinder is locked, and it remains stationary; Lifting condition: Main control valve switching: The operating control mechanism pushes the valve core of the main control valve to the right. After overcoming the right spring, the main control valve is in the right position; At this time, the oil circuit of the pressure oil interface is connected to the lower side of the locking check valve; The control oil on the spring side of the unloading valve is connected to the pressure oil interface, and the unloading valve is closed under the action of the control oil. The pressure oil from the pressure oil interface no longer returns to the oil tank through the second interface; Locking check valve opening: The pressure oil from the pressure oil port acts on the lower side of the locking check valve. When the pressure oil port pressure is greater than the cylinder port pressure, the pressure will push open the locking check valve, connecting the pressure oil port and the cylinder port. The pressure oil enters the lifting cylinder, realizing cylinder lifting; Buffer valve and flow control: The inlet pressure of the throttling slot acts on the non-spring chamber of the buffer valve, and the outlet pressure of the throttling slot acts on the spring chamber of the buffer valve; When the pressure oil port flow increases, the buffer valve return opening increases, and the excess flow flows back to the oil tank through the buffer valve; When the pressure oil port flow decreases, the buffer valve return opening decreases, and the return flow decreases synchronously; Lowering condition: Main control valve status: The operating control mechanism moves the valve core of the main control valve to the left, placing it in the left position; The pressure oil port closes through the oil circuit of the main control valve; The unloading valve springs... The control oil on the spring side is connected to the first interface through the left position of the main control valve, and the control oil cannot build up pressure; the unloading valve works as follows: the pressure oil from the pressure oil interface acts on the upper side of the unloading valve, and only needs to overcome the spring resistance of the unloading valve to open the unloading valve. The pressure oil from the pressure oil interface is connected to the second interface through the unloading valve to achieve unloading and return to the oil tank; the locking check valve works as follows: the pressure oil in the upper spring chamber of the locking check valve is connected to the third interface through the oil passage in the left position of the main control valve, and the upper spring chamber of the locking check valve is unloaded; at this time, the load pressure of the cylinder interface acts on the lower valve core of the locking check valve, overcomes the spring force of the locking check valve, and opens the locking check valve; the cylinder descent oil circuit: the load oil from the cylinder interface is connected to the first interface after passing through the locking check valve and the throttling groove of the main control valve, and the cylinder descends.

[0022] The beneficial effect of adopting the above-mentioned further technical solution is that, in the middle position of the main control valve, port P is closed through the oil passage of the main control valve. Simultaneously, the control oil in the unloading valve spring chamber is connected to port T1 through the middle position of the main control valve, allowing the control oil to unload and return. The pressure oil from port P acts on the non-spring side of the unloading valve. According to the pressure balance formula, the pressure oil from port P only needs to overcome the resistance of the unloading valve spring to open the unloading valve. The pressure oil from port P connects to the T2 unloading return oil tank through the unloading valve. Now, considering the locking check valve, the load pressure oil at port C reaches the upper spring chamber of the locking check valve through the oil passage in the middle of the main control valve. According to the force analysis of the locking check valve, the upper hydraulic pressure and spring force, and the lower hydraulic pressure, since the area of ​​action of the upper pressure is greater than that of the lower pressure, the locking check valve is closed at this time, and the load cylinder at port C is locked. The entire control valve is now in a neutral holding position. The inlet pressure of the throttling slot acts on the lower non-spring chamber of the buffer valve, while the outlet pressure acts on the upper spring chamber. When the flow rate at port P increases, the return oil opening of the buffer valve increases, allowing excess flow to return to the oil tank; conversely, the return oil opening decreases, reducing the return flow. This linearly proportional relationship between the flow rate at the throttling slot and the valve's area ensures a smooth stopping of the lifter's lifting action. Furthermore, when the flow rate is saturated, the lifting flow rate can be controlled independently of engine speed, further improving the smoothness of the lifter's lifting speed; the control valve is in the lifting state at this time.

[0023] The advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is one of the structural schematic diagrams of a tractor lifter control valve provided in an embodiment of the present invention.

[0026] Figure 2 This is a second schematic diagram of the structure of the tractor lifter control valve provided in an embodiment of the present invention.

[0027] Figure 3 This is the third schematic diagram of the structure of the tractor lifter control valve provided in the embodiment of the present invention.

[0028] The following are the reference numerals: 1. Main control valve; 2. Buffer valve; 3. Locking check valve; 4. Unloading valve; 5. Throttling slot; 6. Pressure oil interface; 7. Cylinder interface; 8. First interface; 9. Second interface; 10. Third interface. Detailed Implementation

[0029] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments described are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of 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, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0033] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they 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, and therefore should not be construed as a limitation of the present invention.

[0034] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0035] like Figures 1 to 3 As shown, an embodiment of the present invention provides a tractor lifter control valve, including: a pressure oil interface 6, a cylinder interface 7, a main control valve 1, a buffer valve 2, a lock-up check valve 3, and an unloading valve 4. The main control valve 1 is connected to the pressure oil interface 6, the lock-up check valve 3, and the unloading valve 4 through pipelines. The buffer valve 2 is connected to the pressure oil interface 6, the lock-up check valve 3, and the unloading valve 4 through pipelines. The lock-up check valve 3 is connected to the cylinder interface 7 through a pipeline.

[0036] The beneficial effects of adopting the technical solution of this invention are that by controlling the return oil flow of the buffer valve core, load-sensitive and constant flow control functions are achieved, thus improving the operating performance of the lifter. Through closed-loop control of the main valve core and mechanical servo feedback mechanism, continuous automatic force and position control is achieved during operation. The four control valve modules work together to achieve the control functions of holding, lifting, and lowering. The structure is simple.

[0037] like Figures 1 to 3 As shown, a throttling slot 5 is further provided on the pipeline between the unloading valve 4 and the buffer valve 2.

[0038] The beneficial effect of adopting the above-mentioned further technical solutions is to improve handling performance.

[0039] like Figures 1 to 3 As shown, the main control valve 1, the buffer valve 2, the lock-up check valve 3, and the unloading valve 4 are all disposed in the control valve housing, and the control valve housing is mounted on the lifter housing.

[0040] The advantages of adopting the above-mentioned further technical solution are that the built-in lock-up check valve can be directly installed on the lifting device housing without the need for pipeline connections, saving installation space. The lowering valve adopts a lock-up check valve structure, which can control the sinking amount of the lifting cylinder.

[0041] like Figures 1 to 3 As shown, the control valve housing is further provided with a first interface 8, a second interface 9 and a third interface 10. The first interface 8, the second interface 9 and the third interface 10 are all connected to an oil tank through pipelines. The main control valve 1 is connected to the first interface 8 and the third interface 10 through pipelines respectively. The unloading valve 4 is connected to the second interface 9 through a pipeline.

[0042] The beneficial effect of adopting the above-mentioned further technical solution is that the first interface, the second interface and the third interface are connected to the oil tank, which facilitates oil return.

[0043] like Figures 1 to 3As shown, the main control valve 1 is a three-position six-way valve; the main control valve 1 is provided with a main valve core, and the main valve core is provided with a flow groove.

[0044] The beneficial effect of adopting the above-mentioned further technical solution is that the main control valve adopts a three-position six-way structure and a throttling groove is set on the main valve core to improve the valve's control performance.

[0045] like Figures 1 to 3 As shown, the pressure oil interface 6 is further connected to the pressure oil output by the hydraulic pump via a pipeline; the cylinder interface 7 is connected to the cylinder via a pipeline.

[0046] The beneficial effect of adopting the above-mentioned further technical solution is that the pressure oil output by the hydraulic pump is connected to the pressure oil interface, and the oil cylinder interface is connected to the lifting oil cylinder.

[0047] In addition, the present invention also provides a tractor including the aforementioned tractor lifter control valve.

[0048] like Figures 1 to 3 As shown, this invention also provides a tractor lifting device control method, including: Holding condition: the main control valve 1 is in the neutral position, the unloading valve 4 is open to unload, the locking check valve 3 is closed, and the cylinder is locked; Lifting condition: the main control valve 1 is switched to the lifting position, the spring chamber of the unloading valve 4 is closed by pressure oil, and the pressure oil from the pressure oil port 6 passes through the main control valve 1 and the locking check valve 3 to the cylinder port, pushing the cylinder to lift; Lowering condition: the main control valve 1 is switched to the lowering position, the unloading valve 4 is opened to unload, the control oil on the upper side of the locking check valve 3 is depressurized, the locking check valve 3 is opened, and the load oil from the cylinder port 7 returns to the oil tank through the locking check valve 3 and the main control valve 1, causing the cylinder to lower; When switching between the holding condition, lifting condition, and lowering condition, the buffer valve 2 buffers the pressure impact during the switching.

[0049] The beneficial effects of adopting the technical solution of this invention are that by controlling the return oil flow of the buffer valve core, load-sensitive and constant flow control functions are achieved, thus improving the operating performance of the lifter. Through closed-loop control of the main valve core and mechanical servo feedback mechanism, continuous automatic force and position control is achieved during operation. The four control valve modules work together to achieve the control functions of holding, lifting, and lowering. The structure is simple.

[0050] Furthermore, when switching between operating conditions, improving operating conditions, and decreasing operating conditions, the control performance of the main control valve 1 is optimized through the throttling slot 5.

[0051] The beneficial effect of adopting the above-mentioned further technical solution is that the inlet pressure of the throttling slot acts on the lower non-spring chamber of the buffer valve, and the outlet pressure of the throttling slot acts on the upper spring chamber of the buffer valve. When the flow rate at port P increases, the return oil opening of the buffer valve increases, and the excess flow flows back to the oil tank from the buffer valve; conversely, the return oil opening decreases, and the return oil flow decreases. In this way, the flow rate of the throttling slot is linearly proportional to its own valve port area, achieving a smooth stop of the lifting action of the elevator. In addition, when the flow rate is saturated, the lifting flow rate can be controlled independently of the engine speed, thereby improving the stability of the elevator's lifting speed, and the control valve is in the lifting state at this time.

[0052] Furthermore, maintaining the operating conditions: Pressure oil port 6 oil circuit: Pressure oil port 6 is closed through the oil circuit of main control valve 1. Pressure oil acts on the non-spring side of unloading valve 4, overcoming spring resistance and opening unloading valve 4. Pressure oil from pressure oil port 6 returns to the oil tank through second port 9, and the hydraulic pump is in an unloaded state; Control oil circuit: Control oil from the spring chamber of unloading valve 4 returns to the oil tank through the intermediate position of main control valve 1 and first port 8, unloading the control oil; Locking check valve 3: Load pressure oil from cylinder port 7 passes through the oil in the intermediate position of main control valve 3... The oil cylinder reaches the upper spring chamber of the locking check valve 3, which closes, locking the cylinder and keeping it stationary. Lifting condition: Main control valve 1 switching: The operating control mechanism pushes the valve core of the main control valve 1 to the right, overcoming the right-side spring, and the main control valve 1 is in the right-side position. At this time, the oil circuit of the pressure oil interface 6 is connected to the lower side of the locking check valve 3; the control oil on the spring side of the unloading valve 4 is connected to the pressure oil interface 6, and the unloading valve 4 closes under the action of the control oil, so the pressure oil in the pressure oil interface 6 no longer unloads and returns through the second interface 9. Locking check valve 3 opens: The pressure oil from pressure oil port 6 acts on the lower side of locking check valve 3. When the pressure at pressure oil port 6 is greater than the pressure at cylinder port 7, the pressure will push open locking check valve 3, connecting pressure oil port 6 with cylinder port 7. The pressure oil enters the lifting cylinder, realizing cylinder lifting; Buffer valve 2 and flow control: The inlet pressure of throttle slot 5 acts on the non-spring chamber of buffer valve 2, and the outlet pressure of throttle slot 5 acts on the spring chamber of buffer valve 2. When the flow rate at pressure oil port increases, the return oil opening of buffer valve 2 increases, and the excess flow flows back to the oil tank through buffer valve 2; when the flow rate at pressure oil port 6 decreases, the return oil opening of buffer valve 2 decreases, and the return oil flow decreases synchronously; Lowering condition: Main control valve 1 state: The operating control mechanism moves the valve core of main control valve 1 to the left, placing it in the left position; Pressure oil port 6 closes through the oil circuit of main control valve 1; Unloading valve 4 springs The control oil on the spring side is connected to the first interface 8 through the left position of the main control valve 1, and the control oil cannot build up pressure; the unloading valve 4 works as follows: the pressure oil at the pressure oil interface 6 acts on the upper side of the unloading valve 4, and the unloading valve 4 can be opened by overcoming the spring resistance of the unloading valve 4. The pressure oil at the pressure oil interface is connected to the second interface 9 through the unloading valve 4 to achieve unloading and return to the oil tank; the locking check valve 3 works as follows: the pressure oil in the upper spring chamber of the locking check valve 3 is connected to the third interface 10 through the oil passage in the left position of the main control valve 1, and the upper spring chamber of the locking check valve 3 is unloaded; at this time, the load pressure at the cylinder interface 7 acts on the lower valve core of the locking check valve 3, overcomes the spring force of the locking check valve 3, and opens the locking check valve 3; the cylinder descent oil circuit: the load oil at the cylinder interface 7 is connected to the first interface 8 after passing through the locking check valve 3 and the throttling groove of the main control valve 1, and the cylinder descends.

[0053] The beneficial effect of adopting the above-mentioned further technical solution is that, in the middle position of the main control valve, port P is closed through the oil passage of the main control valve. Simultaneously, the control oil in the unloading valve spring chamber is connected to port T1 through the middle position of the main control valve, allowing the control oil to unload and return. The pressure oil from port P acts on the non-spring side of the unloading valve. According to the pressure balance formula, the pressure oil from port P only needs to overcome the resistance of the unloading valve spring to open the unloading valve. The pressure oil from port P connects to the T2 unloading return oil tank through the unloading valve. Now, considering the locking check valve, the load pressure oil at port C reaches the upper spring chamber of the locking check valve through the oil passage in the middle of the main control valve. According to the force analysis of the locking check valve, the upper hydraulic pressure and spring force, and the lower hydraulic pressure, since the area of ​​action of the upper pressure is greater than that of the lower pressure, the locking check valve is closed at this time, and the load cylinder at port C is locked. The entire control valve is now in a neutral holding position. The inlet pressure of the throttling slot acts on the lower non-spring chamber of the buffer valve, while the outlet pressure acts on the upper spring chamber. When the flow rate at port P increases, the return oil opening of the buffer valve increases, allowing excess flow to return to the oil tank; conversely, the return oil opening decreases, reducing the return flow. This linearly proportional relationship between the flow rate at the throttling slot and the valve's area ensures a smooth stopping of the lifter's lifting action. Furthermore, when the flow rate is saturated, the lifting flow rate can be controlled independently of engine speed, further improving the smoothness of the lifter's lifting speed; the control valve is in the lifting state at this time.

[0054] This invention provides a tractor lifter control valve, which is a new type of force-position lifter control valve with a buffer valve structure. By controlling the return oil flow of the buffer valve core, it can achieve load-sensitive and constant flow control functions, thereby improving the lifter's operating performance.

[0055] In existing solutions, the lifter, hydraulic output multi-way valve, distributor, and hydraulic cylinder are arranged separately and connected by pipelines. This pipeline arrangement is particularly difficult in small and medium horsepower applications with limited space. The lift control valve of this invention has a built-in locking check valve 3, which can be directly installed on the lifter housing without pipeline connection, saving installation space.

[0056] The existing hydraulic system of the mechanical lifting device of the tractor cannot achieve the function of continuous hydraulic output. The force and position lifting control valve of the present invention realizes continuous automatic force and position control during operation through closed-loop control of the main valve core of the control valve and the mechanical servo feedback mechanism.

[0057] This invention provides a lifting control valve with a simple principle and reliable performance. The lifting control valve mainly consists of a main control valve 1, a buffer valve 2, a lock-up check valve 3, and an unloading valve 4. The four control valve modules work together to achieve the control functions of holding, lifting, and lowering. The main control valve 1 adopts a three-position six-way structure and has a throttling groove 5 on the main valve core to improve the valve's operating performance.

[0058] The hydraulic pump outputs pressure oil connected to port P (pressure oil interface), port C (cylinder interface) connected to the lifting cylinder (cylinder), and ports T1 (first interface), T2 (second interface), and T3 (third interface) connected to the oil tank.

[0059] like Figure 1 In the indicated state, at the middle b position of the main control valve 1, port P (pressure oil interface) is closed through the oil passage of the main control valve 1. Simultaneously, the control oil in the spring chamber of the unloading valve 4 is connected to port T1 (first interface 8) through the middle b position of the main control valve 1, allowing the control oil to unload and return. The pressure oil from port P acts on the non-spring side of the unloading valve 4. According to the pressure balance formula, the pressure oil from port P only needs to overcome the resistance of the spring in the unloading valve 4 to open it. The pressure oil from port P connects to the unloading return oil tank of T2 through the unloading valve 4. Now, looking at the locking check valve 3, the load pressure oil at port C reaches the upper spring chamber of the locking check valve 3 through the oil passage at the middle b position of the main control valve 1. According to the force analysis of the locking check valve 3, the upper hydraulic pressure and spring force, and the lower hydraulic pressure, since the area of ​​action of the upper pressure is greater than that of the lower pressure, the locking check valve 3 is closed at this time, and the load cylinder at port C is locked. The entire control valve is now in the neutral holding position.

[0060] like Figure 2 In the indicated state, after the operating control mechanism pushes the main control valve core to move to the right against the spring force on the right side of the main valve core, the main control valve 1 is in the right position c. Port P is connected to the lower side of the locking check valve 3 through the oil circuit of the main control valve 1. At the same time, the control oil on the spring side of the unloading valve 4 is connected to the pressure oil port P through the middle position c of the main control valve 1. Under the action of the control oil, the unloading valve 4 is closed. The pressure oil from port P acts on the lower side of the locking check valve 3. When the pressure at port P is greater than the pressure of the load cylinder at point C, the locking check valve 3 can be opened under the action of the pressure, connecting port P and port C, realizing the lifting action of the load cylinder. At the same time, the inlet pressure of the throttling slot 5 acts on the lower non-spring chamber of the buffer valve 2, and the outlet pressure of the throttling slot 5 acts on the upper spring chamber of the buffer valve 2. When the flow rate at port P increases, the return oil opening of the buffer valve 2 increases, and the excess flow flows back to the oil tank from the buffer valve. Conversely, the return oil opening decreases and the return oil flow decreases. This linearly proportional flow rate through the throttling slot 5 and the area of ​​its own valve port ensures a smooth stopping of the lifting action. Furthermore, when the flow rate is saturated, the lifting flow rate can be controlled independently of engine speed, thereby improving the stability of the lifting speed; the control valve is in the lifting state at this time.

[0061] like Figure 3In the indicated state, after the control mechanism moves the main control valve core 1 to the left for reversal, the main control valve 1 is in the left position a. The oil circuit through port P of the main control valve 1 is closed. At the same time, the control oil on the spring side of the unloading valve 4 is connected to port T1 through the left position a of the main control valve 1, and the control oil cannot build up pressure. The pressure oil from port P acts on the upper side of the unloading valve 4. According to the pressure balance formula, the pressure oil from port P only needs to overcome the resistance of the spring of the unloading valve 4 to open the unloading valve 4. The pressure oil from port P is connected to the unloading port T2 through the unloading valve 4 to achieve unloading and return to the oil tank. Now, looking at the locking check valve 3, the pressure oil in the upper spring chamber is connected to the drain port T3 through the oil passage of the left position a of the main control valve 1. The upper chamber of the locking check valve 3 is unloaded. At this time, the load pressure at port C acts on the valve core on the lower side of the locking check valve 3, overcoming the spring force of the logic check valve 3, opening the locking check valve 3. The load port C is connected to the oil port T1 through the throttling groove of the locking check valve 3 and the main control valve 2. The oil cylinder descends, and the entire control valve is now in the descending position.

[0062] 1. This control valve features a buffer valve 2 structure. By controlling the return oil flow of the buffer valve 2, it achieves load-sensitive and constant flow control functions. 2. The main valve employs throttling control; a flow groove (throttling slot) is located in the valve core of the main valve to improve the control valve's operability. 3. The lowering valve utilizes a lock-up check valve 3 structure, capable of controlling the sag of the lifting cylinder.

[0063] The control valve features a buffer valve 2 structure. By controlling the return oil flow of the buffer valve 2, it achieves load-sensitive and constant flow control functions, improving the lifting device's operational performance and effectively solving the problems of poor operability and low operating efficiency of existing lifting devices. Through the feedback closed loop between the control valve and the mechanical servo mechanism, it achieves automatic force and position control for deep tillage operations. The integrated arrangement of the hydraulic lifting valve, lifting cylinder, and hydraulic pipelines saves installation space and facilitates maintenance.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tractor lifter control valve, characterized in that, include: The system includes a pressure oil interface, a cylinder interface, a main control valve (1), a buffer valve (2), a lock-up check valve (3), and an unloading valve (4). The main control valve (1) is connected to the pressure oil interface, the lock-up check valve (3), and the unloading valve (4) via pipelines. The buffer valve (2) is connected to the pressure oil interface, the lock-up check valve (3), and the unloading valve (4) via pipelines. The lock-up check valve (3) is connected to the cylinder interface via a pipeline.

2. The tractor lifter control valve according to claim 1, characterized in that, A throttling slot (5) is provided on the pipeline between the unloading valve (4) and the buffer valve (2).

3. A tractor lifter control valve according to claim 1, characterized in that, The main control valve (1), the buffer valve (2), the lock-up check valve (3), and the unloading valve (4) are all located in the control valve housing, which is mounted on the lifter housing.

4. A tractor lifter control valve according to claim 3, characterized in that, The control valve housing is provided with a first interface, a second interface and a third interface. The first interface, the second interface and the third interface are all connected to an oil tank through pipelines. The main control valve (1) is connected to the first interface and the third interface through pipelines respectively. The unloading valve (4) is connected to the second interface through a pipeline.

5. A tractor lifter control valve according to claim 1, characterized in that, The main control valve (1) is a three-position six-way valve; the main control valve (1) is provided with a main valve core, and the main valve core is provided with a flow groove.

6. A tractor lifter control valve according to claim 1, characterized in that, The pressure oil interface is connected to the pressure oil output by the hydraulic pump via a pipeline; the cylinder interface is connected to the cylinder via a pipeline.

7. A tractor, characterized in that, The tractor lifter control valve includes any one of claims 1 to 6.

8. A method for controlling a lifting device for a tractor, characterized in that, Based on any one of claims 1 to 6, a tractor lifter control method includes: Maintaining operating conditions: The main control valve (1) is in the neutral position, the unloading valve (4) is open to unload, the locking check valve (3) is closed, and the oil cylinder is locked and does not move; Lifting condition: When the main control valve (1) is switched to the lifting position, the spring chamber of the unloading valve (4) is closed by pressure oil. The pressure oil in the pressure oil port passes through the main control valve (1) and the locking check valve (3) to the cylinder port, pushing the cylinder to lift. Descent condition: The main control valve (1) is switched to the descent position, the unloading valve (4) is opened to unload, the control oil on the upper side of the lock-up check valve (3) is depressurized, the lock-up check valve (3) is opened, and the load oil at the cylinder interface returns to the oil tank through the lock-up check valve (3) and the main control valve (1), and the cylinder descends. When switching between the operating conditions of maintaining, raising and lowering, the buffer valve (2) buffers the pressure shock during the switching.

9. A tractor lift control method according to claim 8, characterized in that, When switching between operating conditions, improving operating conditions and decreasing operating conditions, the control performance of the main control valve (1) is optimized through the throttling slot (5).

10. A tractor lifting device control method according to claim 8, characterized in that, Maintain operating condition: Pressure oil interface oil circuit: The pressure oil interface is closed through the oil circuit of the main control valve (1). The pressure oil acts on the non-spring side of the unloading valve (4), and after overcoming the spring resistance, the unloading valve (4) is opened. The pressure oil of the pressure oil interface returns to the oil tank through the second interface, and the hydraulic pump is in the unloading state. Control oil circuit: The control oil in the spring chamber of the unloading valve (4) returns to the oil tank through the intermediate position of the main control valve (1) and the first interface, and the control oil is unloaded; Locking check valve (3): The load pressure oil of the cylinder interface passes through the oil passage in the middle position of the main control valve (3) and reaches the upper spring chamber of the locking check valve (3). The locking check valve (3) closes, the cylinder is locked and remains stationary. Improved operating conditions: Main control valve switching: The operating control mechanism pushes the valve core of the main control valve (1) to the right. After overcoming the right spring, the main control valve (1) is in the right position. At this time, the oil circuit of the pressure oil interface is connected to the lower side of the lock-up check valve (3). The control oil on the spring side of the unloading valve (4) is connected to the pressure oil interface. The unloading valve (4) is closed under the action of the control oil. The pressure oil of the pressure oil interface is no longer unloaded and returned through the second interface. Locking check valve (3) opens: The pressure oil in the pressure oil port acts on the lower side of the locking check valve (3). When the pressure in the pressure oil port is greater than the pressure in the cylinder port, the pressure will push the locking check valve (3) open, so that the pressure oil port and the cylinder port are connected. The pressure oil enters the lifting cylinder to realize the lifting of the cylinder. Buffer valve (2) and flow control: The inlet pressure of the throttling slot (5) acts on the non-spring chamber of the buffer valve (2), and the outlet pressure of the throttling slot (5) acts on the spring chamber of the buffer valve (2). When the flow rate at the pressure oil interface increases, the return oil opening of the buffer valve (2) increases, and the excess flow flows back to the oil tank through the buffer valve (2). When the flow rate at the pressure oil interface decreases, the return oil opening of the buffer valve (2) decreases, and the return oil flow rate decreases synchronously. Descending condition: Main control valve (1) status: The control mechanism is operated to move the valve core of the main control valve (1) to the left and it is in the left position; the pressure oil interface is closed through the oil circuit of the main control valve (1); the control oil on the spring side of the unloading valve (4) is connected to the first interface through the left position of the main control valve (1), and the control oil cannot build pressure; Working process of unloading valve (4): The pressure oil of the pressure oil port acts on the upper side of the unloading valve (4). As long as the spring resistance of the unloading valve (4) is overcome, the unloading valve (4) can be opened. The pressure oil of the pressure oil port is connected to the second port through the unloading valve (4) to realize unloading and return to the oil tank. Working process of locking check valve (3): The pressure oil in the upper spring chamber of the locking check valve (3) is connected to the third interface through the oil passage in the left position of the main control valve (1), and the upper spring chamber of the locking check valve (3) is unloaded; at this time, the load pressure of the oil cylinder interface acts on the lower valve core of the locking check valve (3), overcoming the spring force of the locking check valve (3) and opening the locking check valve (3); Hydraulic cylinder descent oil circuit: The load oil at the hydraulic cylinder interface passes through the locking check valve (3) and the throttling groove of the main control valve (1) and then connects to the first interface, so that the hydraulic cylinder can descend.

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