Electro-hydraulic control method and system for wet clutch of tractor power take-off

Abstract

An electro-hydraulic control method and system for a tractor power output wet clutch, in the electro-hydraulic control method, when the power output needs to be engaged, the power output engagement separation switch is pressed, at this time, an electric signal is transmitted to a controller; the power output load is controlled through a load adjustment knob, the engagement time adjustment knob is used to adjust the length of the clutch slip time, the output electric signal of the load adjustment knob and the output electric signal of the engagement time adjustment knob are transmitted to the controller, the controller obtains the above-mentioned electric signal and outputs the corresponding pressure value of the electric current to the electric proportional cartridge valve in the electromagnetic valve group according to the preset program, the electric proportional cartridge valve outputs the control pressure to the power output clutch, and the slow engagement process of the clutch is completed. The scheme can realize the slow engagement control of the power output wet clutch, and the buffer effect can be adjusted at any time according to the operation load, the buffer effect can always meet the needs of various operation conditions, and the adaptability is better.

Description

Technical Field

[0001] This invention relates to the field of wet clutch control technology, specifically to an electro-hydraulic control method and system for a wet clutch used in tractor power output. Background Technology

[0002] A tractor power take-off unit (PTO) is a working device that transmits part or even all of the power of a tractor engine to agricultural implements in the form of rotational mechanical energy. It can provide power to balers, seeders, rotary tillers, fertilizer applicators, and sprayers / dust sprayers that do not have their own power units.

[0003] During operation, it is necessary to control the engagement and disengagement of the tractor's power take-off (PTO). Currently, there are two implementation methods: one uses a dry clutch to control power, typically operated with a mechanical lever or hydraulic assist. The user controls the engagement and disengagement of the dry clutch via a power take-off clutch lever. However, this method cannot achieve a soft start during power take-off engagement, making it difficult to control the rate of increase in power output speed within a certain range. Furthermore, the clutch lever cable is heavy, resulting in high operational intensity. The other method uses a wet clutch to control power, controlling it by hydraulically pressing a piston. Compared to a dry clutch, a wet clutch has a simpler structure, more uniform pressure distribution, less and more uniform wear, longer lifespan, and does not require special adjustment of the friction plate clearance during use. The torque capacity can be easily changed by increasing or decreasing the number of clutch plates to adapt to variations in engine displacement, and can also be freely adjusted according to oil pressure. Wet clutches have a larger heat capacity than dry clutches, and the friction surfaces are cooled by oil, resulting in lower temperatures and allowing for longer periods of slippage for gentle engagement. The application of wet clutches in tractor PTOs is becoming increasingly widespread.

[0004] In the engagement control process of wet clutches, to avoid the enormous impact force that would damage the power take-off device and agricultural implements caused by directly engaging the power take-off clutch, a power take-off soft engagement device is generally equipped. This device uses a switching valve to control the on / off of oil pressure, and controls the engagement time of the power take-off clutch by changing the oil flow rate and volume through the addition of a throttle orifice and an accumulator, thus achieving a soft engagement process. However, the size of the throttle orifice and the volume of the accumulator are not easily changed after the product is finalized. As the load on the implements driven by the power take-off changes, the soft engagement effect of the clutch also changes, failing to meet the requirements of new implements. This is specifically reflected in the following two aspects: 1) The clamping torque of a wet clutch cannot be adjusted as needed at any time; 2) The pre-charge and engagement times of a wet clutch cannot be adjusted as needed at any time. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides an electro-hydraulic control method and system for a wet clutch for power output of a tractor, which can realize the soft engagement control of the wet clutch for power output, and the buffering effect can be adjusted at any time according to the working load. The buffering effect can always meet the needs of various working conditions and has better adaptability.

[0006] The technical solution adopted in this invention is: an electro-hydraulic control method for a wet clutch for tractor power output. After the vehicle is started, the working oil establishes working pressure through the sequence valve in the solenoid valve group. This pressure is the maximum working pressure of the system. Since the electro-proportional cartridge valve in the solenoid valve group is not working, this pressure cannot be transmitted to the power output clutch. When power output needs to be engaged, press the power output engagement / disengagement switch. At this time, an electrical signal is transmitted to the controller. The power output load is controlled by the load adjustment knob, and the clutch slip time is adjusted by the engagement time adjustment knob. The output electrical signals of the load adjustment knob and the engagement time adjustment knob are transmitted to the controller. After receiving the above electrical signals, the controller outputs the current with the corresponding pressure value to the electro-proportional cartridge valve in the solenoid valve group according to the preset program. The electro-proportional cartridge valve outputs control pressure to the power output clutch, completing the clutch's slow engagement process.

[0007] As a preferred embodiment, the control pressure change curve over time is divided into four stages: Oil filling stage: used to eliminate the gaps between the friction plates; Oil filling waiting stage: further eliminates pressure fluctuations, the clutch condition is stable, and the output torque is 0 at this time; Slippage stage: The stage in which the power output speed reaches a fixed speed determined by the engine and the transmission ratio from 0. Torque reserve phase: The pressure rises rapidly to reach the system's maximum operating pressure.

[0008] As a preferred embodiment, the shape of the variation curve changes as the load adjustment knob and engagement time adjustment knob are adjusted.

[0009] This solution also includes a control system for an electro-hydraulic control method of a wet clutch for tractor power output, comprising: a solenoid valve assembly, a controller, a power output engagement / disengagement switch, a load adjustment knob, an engagement time adjustment knob, a radiator, an oil suction filter, a double gear pump, an oil discharge filter, and a wet clutch. The solenoid valve assembly includes an electro-proportional cartridge valve, a valve body, a sequence valve, a check valve, an accumulator, a back pressure valve, and a radiator bypass valve. One outlet of the dual gear pump is connected to the inlet of the oil filter. The outlet of the oil filter is simultaneously connected to the P port of the electro-proportional cartridge valve, the 1 port of the sequence valve, and the P1 port of the valve body. The A port of the electro-proportional cartridge valve is connected to the piston cylinder of the wet clutch. The T port of the electro-proportional cartridge valve is connected to the housing and the 3 port of the sequence valve. The 2 port of the sequence valve is connected to the inlet of the check valve. The outlet of the check valve is connected to the inlet of the back pressure valve. The other outlet of the dual gear pump is connected to the inlet of the radiator. The inlet of the radiator is connected to the inlet of the radiator bypass valve. The outlet of the radiator is simultaneously connected to the T3 port of the valve body and the external pipeline T2. The power output engagement / disengagement switch, load adjustment knob, engagement time adjustment knob, and electro-proportional cartridge valve are connected to the steering controller via wiring harnesses. The steering controller is connected to the vehicle's main wiring harness via wiring harnesses.

[0010] As a preferred embodiment, the oil suction port of the dual gear pump is connected to the oil outlet of the oil suction filter element, and the oil inlet of the oil suction filter element is connected to the rear housing.

[0011] As a preferred embodiment, the accumulator is simultaneously connected to the P port of the electro-proportional cartridge valve, the 1 port of the sequence valve, and the P1 port on the valve body.

[0012] As a preferred embodiment, the controller is installed inside the dashboard in the cab; the power output engagement / disengagement switch, load adjustment knob, and engagement time adjustment knob are arranged together on the control panel in the cab.

[0013] The beneficial effects of this invention are: To address the shortcomings of existing technologies, this solution provides an electro-hydraulic control method and system for a wet clutch used in tractor power take-off (PTO) applications through optimized design. This system allows for real-time adjustment via load adjustment knobs and engagement time adjustment knobs. The output electrical signals from these knobs are transmitted to a controller. Upon receiving these signals, the controller outputs a current with the corresponding pressure value to an electro-proportional cartridge valve within the solenoid valve assembly according to a preset program. The electro-proportional cartridge valve then outputs control pressure to the PTO clutch, enabling smooth engagement control of the wet clutch. Furthermore, the buffering effect can be adjusted at any time according to the operating load, consistently meeting the needs of various operating conditions and offering better adaptability. The system itself includes a controller, which can be programmed to accommodate different wet clutches and tractors of varying horsepower, and is easily expandable for automation. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A front view showing the structural layout of an electro-hydraulic control system for a wet clutch used in tractor power output; Figure 2 Hydraulic schematic diagram of an electro-hydraulic control system for a wet clutch used in tractor power output; Figure 3 A schematic diagram of the engagement process of an electro-hydraulic control system for a wet clutch used in tractor power output; Figure 4 This is a schematic diagram of the electro-hydraulic control system for a wet clutch used in tractor power output. Detailed Implementation

[0016] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0017] It should be noted that, unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "a," "an," or "the," and similar words used in the specification and claims of this patent application do not express a limitation of quantity, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the elements or objects preceding "comprising" encompass the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects having the same function.

[0018] Example 1 The following is in conjunction with the appendix Figure 1-4 The structure of the device in this embodiment and the gradual engagement process of the clutch are described in detail below: As attached Figure 1 Appendix Figure 2As shown, an electro-hydraulic control system for a wet clutch used in the power take-off (PTO) of a tractor includes: a solenoid valve assembly 1, a controller 2, a power take-off / disengagement switch 3, a load adjustment knob 4, an engagement time adjustment knob 5, a radiator 6, an oil suction filter 7, a double gear pump 8, an oil outlet filter 9, and a wet clutch 10. The solenoid valve assembly includes an electro-proportional cartridge valve 11, a valve body 12, a sequence valve 13, a check valve 14, an accumulator 15, a back pressure valve 16, and a radiator bypass valve 17. The solenoid valve assembly 1 is fixed to the right side of the gearbox, and the controller 2 is installed in the dashboard of the cab. The power take-off / disengagement switch 3, the load adjustment knob 4, and the engagement time adjustment knob 5 are arranged together on the right side of the cab control panel. The radiator 6 is installed in front of the water tank, the oil suction filter 7 is inserted under the rear housing, the double gear pump 8 is installed at the power take-off port on the right side of the rear housing, the oil outlet filter 9 is installed on the right side of the gearbox frame, and the wet clutch 10 is built into the power take-off housing.

[0019] The suction port of the double gear pump 8 is connected to the outlet port of the suction filter 7, and the inlet port of the suction filter 7 is connected to the rear box. The oil outlet of the rear pump of the double gear pump 8 is connected to the oil inlet of the oil filter 9; the oil outlet of the oil filter 9 is simultaneously connected to the P port of the electro-proportional cartridge valve 11, the 1 port of the sequence valve 13, and the P1 port of the valve body 12; the A port of the electro-proportional cartridge valve 11 is connected to the piston cylinder of the wet clutch 10; the T port of the electro-proportional cartridge valve 11 is connected to the housing and also to the 3 port of the sequence valve 13; the 2 port of the sequence valve 13 is connected to the oil inlet of the check valve 14; the oil outlet of the check valve 14 is simultaneously connected to the oil inlet of the back pressure valve 16; the oil outlet of the back pressure valve 16 is connected to the housing. The oil outlet of the front pump of the double gear pump 8 is connected to the oil inlet of the radiator 6, and the oil inlet of the radiator 6 is connected to the oil inlet of the radiator bypass valve 17; the oil outlet of the radiator 6 is simultaneously connected to the T3 port of the valve body 12 and the external pipeline T2; the accumulator 15 is simultaneously connected to the P port of the electro-proportional cartridge valve 11, the 1 port of the sequence valve 13 and the P1 port on the valve body 12.

[0020] The power output engagement / disengagement switch 3 is connected to the steering controller 2 via a wiring harness; the load adjustment knob 4 and engagement time adjustment knob 5 are connected to the steering controller 2 via a wiring harness; the electric proportional cartridge valve 11 is connected to the steering controller 2 via a wiring harness; the power supply for the steering controller 2 is connected to the vehicle's main wiring harness via a wiring harness.

[0021] This solution also includes a control method for an electro-hydraulic control system of a wet clutch for tractor power output, comprising the following steps: After the vehicle starts, the working fluid establishes working pressure through the sequence valve in the solenoid valve assembly. This pressure is the maximum working pressure of the system. Since the electro-proportional cartridge valve in the solenoid valve assembly is not working, this pressure cannot be transmitted to the power output clutch. When power output needs to be engaged, press the power output engagement / disengagement switch. At this time, an electrical signal is transmitted to the controller. The power output load is controlled by the load adjustment knob, and the clutch slippage time is adjusted by the engagement time adjustment knob. The output electrical signals from both the load adjustment knob and the engagement time adjustment knob are transmitted to the controller. Upon receiving these signals, the controller outputs current to the electro-proportional cartridge valve within the solenoid valve assembly according to a preset program. The electro-proportional cartridge valve outputs control pressure to the power output clutch, completing the clutch's gradual engagement process. This solution is suitable for various power output operating modes, and the gradual engagement effect is adjustable and controllable, meeting the power output control requirements of tractors with different horsepower ranges. The preset control pressure change curve over time is generally divided into four stages: During the oil filling stage, it is used to eliminate the gaps between the friction plates; Oil filling waiting stage: further eliminates pressure fluctuations, the clutch condition is stable, and the output torque is 0 at this time; Slippage stage: The stage in which the power output speed reaches a fixed speed determined by the engine and the transmission ratio from 0. Torque reserve phase: The pressure rises rapidly to reach the system's maximum operating pressure.

[0022] This solution adds two user-adjustable knobs: a load adjustment knob and an engagement time adjustment knob. The load adjustment knob adjusts the position of the slip contact point. For lightly loaded implements, less torque is required, resulting in lower pressure at the end of the slip contact; for heavily loaded implements, more torque is required, resulting in higher pressure at the end of the slip contact. The engagement time adjustment knob adjusts the time from the start to the end of the slip contact, typically 1-2 seconds. A longer time results in a smoother start but accelerates wear on the clutch friction plates, reducing their lifespan and lowering work efficiency. A shorter time results in higher work efficiency but greater impact during engagement, potentially damaging the implement and connecting components. Users can adjust the knob in real-time according to the implement they are using, satisfying both the need for flexible engagement and improving work efficiency.

[0023] Load adjustment: as attached Figure 1 Appendix Figure 3 As shown, the load adjustment knob 4 corresponds to the attached... Figure 3 The light load pressure point on the upper part corresponds to the heavy load adjustment knob 4. Figure 3 The heavy load pressure point on the top, the load adjustment knob 4, the corresponding adjustment process is attached. Figure 3 The gray area represents the range within which the load varies. If the power output load is low, the load adjustment knob 4 can be rotated to the light position; if the power output load is high, the load adjustment knob 4 can be rotated to the heavy position. The pressure between the oil filling stage and the pressure at the set load is the clutch slippage stage; the pressure from the set load to the maximum pressure is the torque reserve stage.

[0024] Adjustment of engagement time: as attached Figure 3 As shown, the engagement time adjustment knob 5 can set the duration of the slip friction stage t1, that is, the time between the clutch transmission torque engagement point pressure (Kiss-Point pressure) and the set maximum torque point pressure. If the engagement time adjustment knob 5 is rotated to the short position, the slope of the curve between the oil filling stage pressure and the pressure at the set load will become steeper; if the engagement time adjustment knob 5 is rotated to the long position, the slope of the curve between the oil filling stage pressure and the pressure at the set load will become gentler.

[0025] Slow-release bonding process: as shown in the attached document Figure 2 Appendix Figure 3 As shown, when the power output engagement / disengagement switch 3 is pressed, the controller outputs current to the electro-proportional cartridge valve 11. The current magnitude meets the pressure requirements of the oil filling stage. The controller outputs current to the electro-proportional cartridge valve 11 according to the load adjustment knob 4 (setting the load size) and the engagement time adjustment knob 5 (setting the engagement time length), thereby controlling the corresponding pressure value. The electro-proportional cartridge valve 11 outputs the corresponding pressure to the wet clutch 10, completing the slow engagement process. During use, the user can adjust the settings based on the engagement effect until the optimal engagement process is achieved.

[0026] The parts not described in detail in this embodiment are existing technologies.

[0027] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.

Claims

1. An electro-hydraulic control system for a wet clutch used in tractor power output, characterized in that: include: The system includes a solenoid valve assembly, a steering controller, a power output engagement / disengagement switch, a load adjustment knob, an engagement time adjustment knob, a radiator, an oil suction filter, a double gear pump, an oil outlet filter, and a wet clutch. The solenoid valve assembly includes an electro-proportional cartridge valve, a valve body, a sequence valve, a check valve, an accumulator, a back pressure valve, and a radiator bypass valve. One outlet of the dual gear pump is connected to the inlet of the oil filter. The outlet of the oil filter is simultaneously connected to the P port of the electro-proportional cartridge valve, the 1 port of the sequence valve, and the P1 port of the valve body. The A port of the electro-proportional cartridge valve is connected to the piston cylinder of the wet clutch. The T port of the electro-proportional cartridge valve is connected to the housing and the 3 port of the sequence valve. The 2 port of the sequence valve is connected to the inlet of the check valve. The outlet of the check valve is connected to the inlet of the back pressure valve. The other outlet of the dual gear pump is connected to the inlet of the radiator. The inlet of the radiator is connected to the inlet of the radiator bypass valve. The outlet of the radiator is simultaneously connected to the T3 port of the valve body and the external pipeline T2. The power output engagement / disengagement switch, load adjustment knob, engagement time adjustment knob, and electro-proportional cartridge valve are connected to the steering controller via wiring harnesses. The steering controller is connected to the vehicle's main wiring harness via wiring harnesses. The control method of the electro-hydraulic control system for a wet clutch for tractor power output includes the following steps: After the vehicle starts, the working fluid establishes working pressure through the sequence valve in the solenoid valve assembly. This pressure is the maximum working pressure of the system. Since the electro-proportional cartridge valve in the solenoid valve assembly is not working, this pressure cannot be transmitted to the power output clutch. When power output needs to be engaged, press the power output engagement / disengagement switch. At this time, an electrical signal is transmitted to the controller. The power output load is controlled by the load adjustment knob, and the clutch slip time is adjusted by the engagement time adjustment knob. The output electrical signals of the load adjustment knob and the engagement time adjustment knob are transmitted to the controller. After receiving the above electrical signals, the controller outputs the current with the corresponding pressure value to the electro-proportional cartridge valve in the solenoid valve group according to the preset program. The electro-proportional cartridge valve outputs control pressure to the power output clutch, completing the clutch's slow engagement process.

2. The electro-hydraulic control system for a wet clutch for tractor power output according to claim 1, characterized in that: The suction port of the double gear pump is connected to the outlet port of the suction filter, and the inlet port of the suction filter is connected to the housing.

3. The electro-hydraulic control system for a wet clutch for tractor power output according to claim 1, characterized in that: The accumulator is simultaneously connected to the P port of the electro-proportional cartridge valve, the 1 port of the sequence valve, and the P1 port on the valve body.

4. The electro-hydraulic control system for a wet clutch for tractor power output according to claim 1, characterized in that: The controller is installed in the dashboard of the cab; the power output engagement / disengagement switch, load adjustment knob, and engagement time adjustment knob are arranged together on the control panel in the cab.

5. The control method for the electro-hydraulic control system of a wet clutch for tractor power output according to any one of claims 1-4, characterized in that: The curve of the control pressure changing over time is divided into four stages: Oil filling stage: used to eliminate the gaps between the friction plates; Oil filling waiting stage: further eliminates pressure fluctuations, the clutch condition is stable, and the output torque is 0 at this time; Slippage stage: The stage in which the power output speed reaches a fixed speed determined by the engine and the transmission ratio from 0. Torque reserve phase: The pressure rises rapidly to reach the system's maximum operating pressure.

6. The control method according to claim 5, characterized in that: The shape of the variation curve changes as the load adjustment knob and engagement time adjustment knob are adjusted.

Images