Speed control system of tractor and power reversing control method

Abstract

The invention discloses a speed control system of a tractor and a power reversing control method, and the speed control system of the tractor comprises a control unit, a transmission unit and a hydraulic unit, the control unit is electrically connected with the direction handle, the transmission input shaft speed sensor, the clutch output shaft speed sensor, the front axle / rear axle input speed sensor, the forward electro-hydraulic proportional valve and the reverse gear electro-hydraulic proportional valve. The control unit is configured to receive signals sent by a direction handle, a transmission input shaft speed sensor, a clutch output shaft speed sensor and a front axle / rear axle input speed sensor in the transmission unit; and in response to a reversing request signal sent by the direction handle, the control signal is sent to a forward electro-hydraulic proportional valve and a reverse gear electro-hydraulic proportional valve in the hydraulic unit. Rapid and stable starting and reversing under different loads can be achieved, the clutch is protected in the running period, the tillage efficiency is improved, and meanwhile overload of a transmission system is avoided.

Description

Technical Field

[0001] This invention relates to the field of tractor technology, and in particular to the transmission system of tractors and the power reversal control method. Background Technology

[0002] Currently, the main types of transmission systems and reversing methods for tractors are as follows:

[0003] 1. Mechanical reversing: Gears are engaged by a lever. Disadvantages: Requires the vehicle to stop before shifting gears, is laborious to operate, extremely inefficient, and cannot be reversed while in motion.

[0004] 2. Conventional hydraulic reversing: This method uses a wet clutch assembly, where the clutch engagement and disengagement are controlled by hydraulic oil. Disadvantages: There is a power interruption "window" when switching between forward and reverse gears, causing vehicle jerking; the clutch engagement has a large impact, affecting driving comfort and component lifespan; for high-horsepower tractors like the 1204, the reversing impact severely affects the quality of traction operations (such as plowing and harrowing).

[0005] Referring to Chinese patent application document CN110307325A, entitled "A Transmission Device for Tractors," a transmission device for tractors is disclosed, comprising: a main transmission, a secondary transmission, and a transfer case idler pulley. The main and secondary transmissions are arranged sequentially, with one end of the main transmission connected to the tractor's front transmission case, one end of the secondary transmission connected to the tractor's rear axle, and the transfer case idler pulley connected to the tractor's transfer case. This arrangement allows power to be transmitted to the tractor's rear axle, front axle, and power take-off shaft. The combination of the main and secondary transmissions enables 16 gears. The main transmission uses synchronizers for non-stop shifting; however, this device still exerts a significant impact on the tractor during reversals, preventing a smoother start and reversal during operation and failing to balance tillage quality and efficiency. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide a tractor transmission system and a power reversing control method, which enables the tractor to reverse more smoothly during operation, while ensuring the quality and efficiency of tillage.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A tractor transmission system includes: a control unit A1, a transmission unit, and a hydraulic unit.

[0009] The transmission unit includes an input component, a reversing component, a shifting component, a front axle output component, and a rear axle output component. The input component includes a transmission input shaft and a first gear Z1 and a second gear Z2 fixed on the transmission input shaft. The first gear Z1 and the second gear Z2 are coaxial and rotate synchronously. The reversing component includes a clutch output shaft and a fourth gear Z4 and a fifth gear Z5 loosely fitted on the clutch output shaft. The fourth gear Z4 meshes with a sixth gear Z6, and the sixth gear Z6 meshes with the first gear Z1. The fifth gear Z5 meshes with the second gear Z2. The fourth gear Z4 engages or disengages with the clutch output shaft via a reversing clutch KR, and the fifth gear Z5 engages with the clutch output shaft via a forward clutch KV. The clutch output shaft engages or disengages, and is connected to the shifting component. The shifting component changes the transmission ratio by switching different gear combinations. The input shaft of the rear axle output component is fixedly connected to or integrally formed with the output shaft of the shifting component. The 28th gear Z28 is fixedly connected to the output shaft of the shifting component. The 28th gear Z28 is connected to the input shaft of the front axle output component. The transmission unit also includes a transmission input shaft speed sensor n1 for detecting the speed of the transmission input shaft, a clutch output shaft speed sensor n2 for detecting the speed of the clutch output shaft, and a front axle / rear axle input speed sensor n3 for detecting the speed of the input shaft of the front axle output component or the input shaft of the rear axle output component.

[0010] The hydraulic unit includes a forward electro-hydraulic proportional valve K1 and a reverse electro-hydraulic proportional valve K2. The oil inlet of the forward electro-hydraulic proportional valve K1 is connected to the oil tank, and the working oil port of the forward electro-hydraulic proportional valve K1 is connected to the oil chamber of the forward clutch KV. The oil inlet of the reverse electro-hydraulic proportional valve K2 is connected to the main oil circuit, and the working oil port of the reverse electro-hydraulic proportional valve K2 is connected to the oil chamber of the reverse clutch KR.

[0011] Control unit A1 is electrically connected to the steering handle, drive input shaft speed sensor n1, clutch output shaft speed sensor n2, front / rear axle input speed sensor n3, forward electro-hydraulic proportional valve K1, and reverse electro-hydraulic proportional valve K2, respectively. Control unit A1 is configured to receive signals sent by the steering handle, drive input shaft speed sensor n1, clutch output shaft speed sensor n2, and front / rear axle input speed sensor n3 in the transmission unit, and to send control signals to the forward electro-hydraulic proportional valve K1 and reverse electro-hydraulic proportional valve K2 in the hydraulic unit in response to the reversing request signal sent by the steering handle.

[0012] In some embodiments, in the transmission unit, the transmission input shaft is connected or disconnected from the PTO device via a PTO clutch KP.

[0013] In the hydraulic unit, the oil tank is connected to the first oil pump, which is used to draw oil from the oil tank to the main oil circuit. The input end of the first relief valve is connected to the main oil circuit, and the output end of the first relief valve is connected to the lubrication oil circuit. The input end of the second relief valve is connected to the main oil circuit, and the output end of the second relief valve is connected to the PTO valve group through the first oil circuit. The output end of the second relief valve is connected to the forward electro-hydraulic proportional valve K1 and the reverse electro-hydraulic proportional valve K2 through the second oil circuit. The PTO valve group is used to control the PTO clutch KP.

[0014] In some embodiments, the PTO valve assembly includes a PTO clutch electro-hydraulic proportional valve K3 and a PTO clutch solenoid valve K4. The output end of the second relief valve is connected to the input port of the PTO clutch electro-hydraulic proportional valve K3 through a first oil circuit. The working port of the PTO clutch electro-hydraulic proportional valve K3 is connected to the inlet port of the PTO clutch solenoid valve K4. The working port of the PTO clutch solenoid valve K4 is connected to the PTO clutch KP. The control unit A1 is electrically connected to the PTO clutch electro-hydraulic proportional valve K3 and the PTO clutch solenoid valve K4.

[0015] In some embodiments, the forward electro-hydraulic proportional valve K1 is provided with a forward pressure sensor n5, the reverse electro-hydraulic proportional valve K2 is provided with a reverse pressure sensor n6, and the PTO clutch electro-hydraulic proportional valve K3 is provided with a PTO pressure sensor. The forward pressure sensor n5, the reverse pressure sensor n6, and the PTO pressure sensor are electrically connected to the control unit A1.

[0016] The present invention also provides a power reversing control method, applied to the transmission system of a tractor described above, comprising the following steps:

[0017] S1, Control unit A1 responds to the reversing request signal sent by the steering handle, controls the electro-hydraulic proportional valve corresponding to the target clutch to open its valve port to a predetermined opening degree within a predetermined time A, so as to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plates initially contact.

[0018] S2. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is greater than the predetermined speed, the valve port of the electro-hydraulic proportional valve corresponding to the target clutch is opened at a linear speed.

[0019] S3. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the electro-hydraulic proportional valve corresponding to the target clutch is directly opened to the maximum within the predetermined time B.

[0020] In some embodiments, the target clutch is a forward clutch KV, and the starting control process includes the following steps:

[0021] B1. In response to the reversing request signal sent by the steering handle, the control unit A1 controls the forward electro-hydraulic proportional valve K1 to open its valve port to the first predetermined opening degree within a first predetermined time, so as to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plates initially contact.

[0022] B2. When the oil supply pressure of the forward electro-hydraulic proportional valve K1 reaches the first predetermined pressure, the forward electro-hydraulic proportional valve K1 is controlled to open to the second predetermined degree within a second predetermined time, so that its oil supply pressure rises linearly to the second predetermined pressure within the second predetermined time.

[0023] B3. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is greater than the first predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 is opened at the first linear speed.

[0024] B4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 will be directly opened to the maximum within the third predetermined time.

[0025] In some embodiments, the target clutch is a reverse clutch KR, and the control process for changing the forward direction to the reverse direction includes the following steps:

[0026] C1, Control Unit A1 responds to the reversing request signal sent by the steering handle, controls the reverse electro-hydraulic proportional valve K2 to open its valve port to the third predetermined opening degree within the fourth predetermined time, so as to quickly fill the hydraulic cylinder of the reverse clutch KR with oil, eliminate the piston clearance, and make the friction plate initially contact. At the same time, it controls the forward electro-hydraulic proportional valve K1 of the forward clutch KV to linearly reduce its valve port opening degree.

[0027] C2. When the vehicle forward speed obtained from the front / rear axle input speed sensor n3 is less than the second predetermined speed, the forward electro-hydraulic proportional valve K1 is closed within the fifth predetermined time to completely disengage the forward clutch KV, and the valve port of the reverse electro-hydraulic proportional valve K2 is controlled to open to the fourth predetermined opening degree, so that the pressure of the reverse electro-hydraulic proportional valve K2 is maintained at the third predetermined pressure, so that the friction plate is in a slipping state and begins to transmit torque.

[0028] C3. When the vehicle's reverse speed, obtained from the front / rear axle input speed sensor n3, is greater than the third predetermined speed, the valve port of the reverse gear electro-hydraulic proportional valve K2 is opened at the second linear speed.

[0029] C4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the reverse electro-hydraulic proportional valve K2 will be directly opened to the maximum within the sixth predetermined time.

[0030] In some embodiments, the target clutch is a forward clutch KV, and the control process for changing from reverse direction to forward direction includes the following steps:

[0031] D1. Control unit A1 responds to the reversing request signal sent by the steering handle and controls the forward electro-hydraulic proportional valve K1 to open its valve port to the fifth predetermined opening degree within the seventh predetermined time to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plate initially contact. At the same time, it controls the reverse electro-hydraulic proportional valve K2 of the reverse clutch KR to linearly reduce its valve port opening degree.

[0032] D2. When the reverse speed of the vehicle obtained by the front / rear axle input speed sensor n3 is less than the fourth predetermined speed, the reverse electro-hydraulic proportional valve K2 is closed within the eighth predetermined time to completely disengage the reverse clutch KR, and the valve port of the forward electro-hydraulic proportional valve K1 is controlled to open to the sixth predetermined opening degree, so that the pressure of the forward electro-hydraulic proportional valve K1 is maintained at the fourth predetermined pressure, so that the friction plate is in a slipping state and begins to transmit torque.

[0033] D3. When the vehicle forward speed obtained from the front / rear axle input speed sensor n3 is greater than the fifth predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 is opened at the third linear speed.

[0034] D4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 will be directly opened to the maximum within the ninth predetermined time.

[0035] In some embodiments, the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is calculated by sampling simultaneously every 100ms-200ms and calculating the speed difference.

[0036] In some embodiments, during operation, when the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is greater than 30-100 revolutions and lasts for 700ms-1.5s, the target clutch is quickly disengaged to protect the clutch.

[0037] The present invention has the following beneficial effects:

[0038] This invention, through the installation of a transmission input shaft speed sensor, a clutch output shaft speed sensor, and a front / rear axle input speed sensor, can acquire the transmission input shaft speed, clutch output shaft speed, and front / rear axle input speed. This allows for the acquisition of information such as the speed difference between clutch input and output, actual driving speed, and gear settings. This enables accurate assessment of clutch slippage during starting, running, and reversing operations. Furthermore, by controlling the forward and reverse electro-hydraulic proportional valves, it achieves rapid and smooth starting and reversing under different loads, protects the clutch during driving, ensures tillage quality, improves tillage efficiency, and avoids transmission system overload caused by reversing shocks.

[0039] This invention uses the vehicle speed obtained by the front / rear axle input speed sensor as the standard for opening the valve port of the electro-hydraulic proportional valve corresponding to the target clutch. This ensures smooth starting and forward / reverse gear shifting. Using the speed difference as the judgment standard, it can increase the speed of starting and forward / reverse gear shifting while maintaining smoothness. This improves the shifting rate while ensuring the smoothness of the tractor's shifting, thereby increasing the tractor's working efficiency and protecting the clutch from damage.

[0040] The power reversing control method of this invention can be adapted to a transmission system with multiple forward gears and multiple reverse gears, enabling fast and smooth start-up and reversing. The entire start-up time is guaranteed to be completed within 2-3.5 seconds. When the tractor speed is below 5 km / h, the reversing can be completed within 3-4 seconds, and when the tractor speed is below 10 km / h, the reversing can be completed within 5-6 seconds. Compared with the start-up and reversing method without speed sensor feedback, it can save 10%-30% of the time, improve work efficiency, and protect the friction plates, extending the service life of the friction plates by more than 400 hours. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the transmission unit in the tractor's gear transmission system.

[0042] Figure 2 This is a hydraulic schematic diagram of the hydraulic unit in the transmission system of a tractor.

[0043] Figure 3 This is a control principle diagram of the control unit in the transmission system of a tractor;

[0044] Figure 4 This is a schematic diagram of the connection structure of the transmission unit, hydraulic unit and control unit in the transmission system of a tractor;

[0045] Figure 5 These are the pressure curves of the forward electro-hydraulic proportional valve and the reverse electro-hydraulic proportional valve when the tractor reverses direction.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1. Transmission input shaft; 2. Clutch output shaft; 3. Output shaft of shifting component; 4. Input shaft of rear axle output component; 5. Input shaft of front axle output component; 6. First relief valve; 7. Second relief valve; 8. Main oil circuit; 9. First oil circuit; 10. Second oil circuit; 11. First oil pump; 12. Second oil pump. Detailed Implementation

[0048] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0049] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for fixing, coupling, or communication.

[0050] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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. Therefore, they should not be construed as limitations on the present invention.

[0051] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0052] refer to Figures 1-4 The transmission system of the tractor of the present invention includes: a control unit A1, a transmission unit, and a hydraulic unit.

[0053] The transmission unit includes an input component, a reversing component, a shifting component, a front axle output component, and a rear axle output component. The input component includes a transmission input shaft 1 and a first gear Z1 and a second gear Z2 fixed on the transmission input shaft 1. The first gear Z1 and the second gear Z2 are coaxial and rotate synchronously. The reversing component includes a clutch output shaft 2 and a fourth gear Z4 and a fifth gear Z5 loosely fitted on the clutch output shaft 2. The fourth gear Z4 meshes with a sixth gear Z6, and the sixth gear Z6 meshes with the first gear Z1. The fifth gear Z5 meshes with the second gear Z2. The fourth gear Z4 engages or disengages from the clutch output shaft 2 via a reversing clutch KR, and the fifth gear Z5 engages or disengages via a forward clutch KV. The clutch output shaft 2 is engaged or disengaged, and the clutch output shaft 2 is connected to the shifting component. The shifting component changes the transmission ratio by switching different gear combinations. The input shaft 4 of the rear axle output component is fixedly connected to or integrally formed with the output shaft 3 of the shifting component. The twenty-eighth gear Z28 is fixedly connected to the output shaft 3 of the shifting component. The twenty-eighth gear Z28 is connected to the input shaft 5 of the front axle output component. The transmission unit also includes a transmission input shaft speed sensor n1 for detecting the rotational speed of the transmission input shaft 1, a clutch output shaft speed sensor n2 for detecting the speed of the clutch output shaft 2, and a front axle / rear axle input speed sensor n3 for detecting the rotational speed of the input shaft 5 of the front axle output component or the rotational speed of the input shaft 4 of the rear axle output component.

[0054] The hydraulic unit includes a forward electro-hydraulic proportional valve K1 and a reverse electro-hydraulic proportional valve K2. The oil inlet of the forward electro-hydraulic proportional valve K1 is connected to the oil tank, and the working oil port of the forward electro-hydraulic proportional valve K1 is connected to the oil chamber of the forward clutch KV. The oil inlet of the reverse electro-hydraulic proportional valve K2 is connected to the main oil circuit 8, and the working oil port of the reverse electro-hydraulic proportional valve K2 is connected to the oil chamber of the reverse clutch KR.

[0055] Control unit A1 is electrically connected to the steering handle, drive input shaft speed sensor n1, clutch output shaft speed sensor n2, front / rear axle input speed sensor n3, forward electro-hydraulic proportional valve K1, and reverse electro-hydraulic proportional valve K2, respectively. Control unit A1 is configured to receive signals sent by the steering handle, drive input shaft speed sensor n1, clutch output shaft speed sensor n2, and front / rear axle input speed sensor n3 in the transmission unit, and to send control signals to the forward electro-hydraulic proportional valve K1 and reverse electro-hydraulic proportional valve K2 in the hydraulic unit in response to the reversing request signal sent by the steering handle.

[0056] This invention utilizes a transmission input shaft speed sensor n1, a clutch output shaft speed sensor n2, and a front / rear axle input speed sensor n3 to acquire the speeds of the transmission input shaft 1, clutch output shaft 2, and front / rear axle input speeds. This allows for the acquisition of information such as the speed difference between clutch input and output, actual driving speed, and gear settings. This enables accurate judgment of clutch slippage during starting, running, and reversing operations. The transmission unit is connected to a hydraulic unit and control unit A1. By controlling the forward electro-hydraulic proportional valve K1 and the reverse electro-hydraulic proportional valve K2, rapid and smooth starting and reversing under different loads can be achieved, as well as clutch protection during driving. Simultaneously, the forward clutch KV and the reverse clutch KR are each equipped with proportional valves connected to the oil tank, enabling faster clutch control and flow controllability. Based on different feedback information from the speed sensors, the opening of the electro-hydraulic proportional valves is controlled to regulate the engagement degree of the clutch friction plates, reducing engagement shock. This is particularly suitable for frequent turning operations. In this embodiment, the forward electro-hydraulic proportional valve K1 and the reverse electro-hydraulic proportional valve K2 are two-position three-way solenoid proportional valves.

[0057] In this embodiment, the retraction clutch KR is used in this embodiment and some other embodiments, in which the transmission input shaft 1 is connected or separated from the PTO device through the PTO clutch KP in the transmission unit.

[0058] In the hydraulic unit, the oil tank is connected to the first oil pump 11, which draws oil from the tank to the main oil circuit 8. The input end of the first relief valve 6 is connected to the main oil circuit 8, and the output end of the first relief valve 6 is connected to the lubrication circuit. The input end of the second relief valve 7 is connected to the main oil circuit 8, and the output end of the second relief valve 7 is connected to the PTO valve assembly via the first oil circuit 9. The output end of the second relief valve 7 is also connected to the forward electro-hydraulic proportional valve K1 and the reverse electro-hydraulic proportional valve K2 via the second oil circuit 10. The PTO valve assembly is used to control the PTO clutch KP. This configuration, through the diversion of the output end of the second relief valve 7, achieves independent control of PTO operation and vehicle movement, and features a simple and compact structure, reducing costs and installation space.

[0059] In this embodiment and some other embodiments, the PTO valve assembly includes a PTO clutch electro-hydraulic proportional valve K3 and a PTO clutch solenoid valve K4. The output end of the second relief valve 7 is connected to the input port of the PTO clutch electro-hydraulic proportional valve K3 via the first oil passage 9. The working port of the PTO clutch electro-hydraulic proportional valve K3 is connected to the inlet port of the PTO clutch solenoid valve K4. The working port of the PTO clutch solenoid valve K4 is connected to the PTO clutch KP. The control unit A1 is electrically connected to the PTO clutch electro-hydraulic proportional valve K3 and the PTO clutch solenoid valve K4. The PTO clutch electro-hydraulic proportional valve K3 achieves precise pressure control of the PTO clutch and reduces engagement shock. The PTO clutch solenoid valve K4 can quickly disconnect the PTO connection when the system detects a fault. In this embodiment, the PTO clutch electro-hydraulic proportional valve K3 is a two-position three-way solenoid proportional valve, and the PTO clutch solenoid valve K4 is a two-position three-way solenoid valve.

[0060] In this embodiment and some other embodiments, in the hydraulic unit, the oil tank is also connected to a second oil pump 12. The second oil pump 12 is used to draw oil from the oil tank to a third oil circuit, which is connected to the lifting cylinder in the suspension system. The dual-pump setup isolates the travel system from the suspension system, making the system more stable, and the oil circuit is simple and responsive.

[0061] In this embodiment and some other embodiments, the forward electro-hydraulic proportional valve K1 is equipped with a forward pressure sensor n5, the reverse electro-hydraulic proportional valve K2 is equipped with a reverse pressure sensor n6, and the PTO clutch electro-hydraulic proportional valve K3 is equipped with a PTO pressure sensor. The forward pressure sensor n5, the reverse pressure sensor n6, and the PTO pressure sensor are electrically connected to the control unit A1. This configuration allows the actual pressure established by the forward electro-hydraulic proportional valve K1, the reverse electro-hydraulic proportional valve K2, and the PTO clutch electro-hydraulic proportional valve K3 to be fed back to the controller, achieving closed-loop control, eliminating the influence of fluctuations in oil temperature and flow rate on pressure, and ensuring the accuracy of the clutch engagement process.

[0062] In this embodiment and some other embodiments, the control unit A1 is also electrically connected to the angular displacement sensor n7, which is installed on the rear lifting mechanism. By detecting the change in the tilt angle of the rear lifting mechanism relative to the horizontal plane, the lifting height information is obtained, enabling the system to work in deep coordination with the rear lifting mechanism. During PTO operation, if the implement is detected to be lifted to a predetermined safe height, the controller will actively disengage the PTO clutch KP, thereby effectively avoiding power waste and mechanism interference, and ensuring operational safety.

[0063] In this embodiment and some other embodiments, the control unit A1 is also electrically connected to the temperature sensor n4, which is installed in the oil circuit of the hydraulic unit. The real-time oil temperature is obtained through the temperature sensor n4. Since the oil viscosity is different when the oil temperature is different, the actual amount of oil entering the clutch and the pressure built up will be different even if the same PWM signal is output to the proportional valve. Therefore, the clutch can be controlled more accurately by setting parameters according to the oil temperature. For example, the pre-charge pressure value during starting and reversing can be dynamically confirmed according to multiple parameters such as clutch oil temperature, engine load and current gear, so as to achieve more precise control of the clutch engagement state and make starting and reversing smoother.

[0064] In this embodiment and some other embodiments, the transmission input shaft speed sensor n1, the clutch output shaft speed sensor n2, and the front / rear axle input speed sensor n3 are mounted on the housing of the transmission unit. The clutch output shaft 2 is fixedly connected to the gear shaft of the twelfth gear Z12, which is connected to the shifting component. The twenty-eighth gear Z28 is meshed with the thirty-first gear Z31, which is fixedly connected to the input shaft 5 of the front axle output component. The probe of the transmission input shaft speed sensor n1 is aligned with the second gear Z2, the probe of the clutch output shaft speed sensor n2 is aligned with the twelfth gear Z12, and the probe of the front / rear axle input speed sensor n3 is aligned with the thirty-first gear Z31. This configuration makes the installation of the speed sensors convenient and reliable. During gear shifting, the control unit obtains the actual operating speed by comparing the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 with the front / rear axle input speed sensor n3, and accurately controls the clutch engagement and disengagement pressure.

[0065] In this embodiment and some other embodiments, the shifting component includes a transmission input shaft 1 of the shifting component and fourteenth gear Z14, fifteenth gear Z15, sixteenth gear Z16, seventeenth gear Z17, eighteenth gear Z18, and nineteenth gear Z19 loosely fitted on the transmission input shaft 1 of the shifting component, as well as an intermediate shaft of the shifting component and twentieth gear Z20, twenty-first gear Z21, twenty-second gear Z22, twenty-third gear Z23, twenty-fourth gear Z24, twenty-fifth gear Z25, and twenty-sixth gear Z26 fixed on the intermediate shaft of the shifting component, and an output of the shifting component. Shaft 3 and the twenty-seventh gear Z27, which is loosely fitted on the output shaft 3 of the shifting component, and the twenty-eighth gear Z28, which is fixed on the output shaft 3 of the shifting component, are connected. A first synchronizer T1 is provided between the fourteenth gear Z14 and the fifteenth gear Z15. The first synchronizer T1 can engage with either the fourteenth gear Z14 or the fifteenth gear Z15, enabling either the fourteenth gear Z14 or the fifteenth gear Z15 to rotate synchronously with the transmission input shaft 1 of the shifting component. A second synchronizer T2 is provided between the sixteenth gear Z16 and the seventeenth gear Z17. The second synchronizer T2 can engage with either the sixteenth gear Z16 or the seventeenth gear Z17. Z17 engages, enabling either the sixteenth gear Z16 or the seventeenth gear Z17 to rotate synchronously with the transmission input shaft 1 of the shifting component. A third synchronizer T3 is provided between the eighteenth gear Z18 and the nineteenth gear Z19, which can engage with either the eighteenth gear Z18 or the nineteenth gear Z19 to enable them to rotate synchronously with the transmission input shaft 1 of the shifting component. A fourth synchronizer T4 is provided between the twenty-sixth gear Z26 and the twenty-seventh gear Z27, which can engage with either the twenty-sixth gear Z26 or the twenty-seventh gear Z27. 7. The output shaft 3 of the shifting component rotates synchronously with the intermediate shaft of the shifting component, or the output shaft 3 of the shifting component rotates synchronously with the 27th gear Z27. The input shaft 5 of the front axle output component is loosely fitted with the 29th gear Z29 and the 30th gear Z30, which are coaxially fixedly connected. The 26th gear Z26 meshes with the 29th gear Z29, and the 27th gear Z27 meshes with the 30th gear Z30. The transmission input shaft 1 of the shifting component is connected to the clutch output shaft 2. Through different combinations of clutches and synchronizers, 12 forward gears + 12 reverse gears can be output.

[0066] In this embodiment and some other embodiments, a 32nd gear Z32 is loosely fitted on the input shaft 5 of the front axle output component. A front axle synchronizer T5 is also provided on the input shaft 5 of the front axle output component. The front axle synchronizer T5 can engage with the 32nd gear Z32, causing the input shaft 5 of the front axle output component to rotate synchronously with the 32nd gear Z32. The 32nd gear Z32 meshes with the 33rd gear Z33, and the 33rd gear Z33 is coaxially and fixedly connected to the output shaft of the front axle output component. The front axle synchronizer T5 allows switching between two-wheel drive and four-wheel drive.

[0067] refer to Figure 3 The diagram below shows the wiring diagram of the control unit A1 and its connection to some components. In this embodiment, the control unit A1 is connected to the transmission input shaft speed sensor n1, the clutch output shaft speed sensor n2, the front axle / rear axle input speed sensor n3, the temperature sensor n4, the forward pressure sensor n5, the reverse pressure sensor n6, the PTO pressure sensor, the angular displacement sensor n7, the diagnostic interface C1, the electro-hydraulic servo valve C2, the vehicle interface C3, and the RS232 interface C4 (diagnostic interface). The electro-hydraulic servo valve C2 includes: the forward electro-hydraulic proportional valve K1, the reverse electro-hydraulic proportional valve K2, and the PTO clutch electro-hydraulic proportional valve K3.

[0068] This embodiment also discloses a power reversing control method, applied to the transmission system of the tractor described above, comprising the following steps:

[0069] S1, Control unit A1 responds to the reversing request signal sent by the steering handle, controls the electro-hydraulic proportional valve corresponding to the target clutch to open its valve port to a predetermined opening degree within a predetermined time A, so as to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plates initially contact.

[0070] S2. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is greater than the predetermined speed, the valve port of the electro-hydraulic proportional valve corresponding to the target clutch is opened at a linear speed.

[0071] S3. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the electro-hydraulic proportional valve corresponding to the target clutch is directly opened to the maximum within the predetermined time B.

[0072] In step S2, the vehicle speed obtained by the front / rear axle input speed sensor n3 is the standard for opening the valve port of the electro-hydraulic proportional valve corresponding to the target clutch, which can ensure smooth starting and forward / reverse gear shifting. In step S3, the speed difference value is used as the judgment standard to increase the speed of starting and forward / reverse gear shifting while maintaining smoothness. When the tractor is working, it may need to shift forward / reverse multiple times to reach the required working state. This embodiment of the invention can improve the shifting rate while ensuring the smoothness of tractor shifting, thereby improving work efficiency. In this embodiment, the shifting includes starting and forward / reverse gear shifting.

[0073] In this embodiment and some other embodiments, the target clutch is the forward clutch KV, and the starting control process includes the following steps:

[0074] B1. In response to the reversing request signal sent by the steering handle, the control unit A1 controls the forward electro-hydraulic proportional valve K1 to open its valve port to the first predetermined opening degree within a first predetermined time, so as to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plates initially contact.

[0075] B2. When the oil supply pressure of the forward electro-hydraulic proportional valve K1 reaches the first predetermined pressure, the forward electro-hydraulic proportional valve K1 is controlled to open to the second predetermined degree within a second predetermined time, so that its oil supply pressure rises linearly to the second predetermined pressure within the second predetermined time.

[0076] B3. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is greater than the first predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 is opened at the first linear speed.

[0077] B4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 will be directly opened to the maximum within the third predetermined time.

[0078] In this embodiment, the starting process involves sampling the engine speed and rapidly increasing clutch pressure within 0.2 seconds based on the real-time engine speed. Once the corresponding calibrated pressure (first predetermined pressure) is reached, the pressure is maintained stably for 0.5 seconds before continuing to increase pressure. During this process, the speeds of gears Z2 and Z12 are sampled in real time. The difference between the clutch input speed and clutch output speed is calculated in real time. When the speed difference is less than 20 revolutions per minute, pressure is directly applied to the clutch working pressure, ensuring full clutch engagement. This reduces clutch slippage time and enables rapid and smooth starting under different loads. Specifically, control unit A1 first receives a starting command: the transmission controller receives a starting request signal from the operator (e.g., switching from neutral (N) to drive (F)).

[0079] Then, pre-charging and pressure control are performed: The controller sends a command to the electro-hydraulic proportional valve K1, opening its valve to a predetermined degree (first predetermined opening) within 0.2-0.3 seconds, rapidly charging the clutch cylinder with oil, eliminating piston clearance, and allowing the friction plates to initially contact but not yet transmit large torque. When the detected pressure reaches 0.2 MPa (first predetermined pressure), the proportional valve is controlled to open to a second predetermined degree within the next second (second predetermined time), causing its oil supply pressure to linearly rise to 0.4 MPa (second predetermined pressure) within 1 second (second predetermined time). Simultaneously, the vehicle speed is detected by the front / rear axle input speed sensor n3. When the vehicle speed is determined to be greater than 0.2-0.3 MPa... At M / H (first predetermined speed) or for a maximum of 1 second (the maximum 1 second setting prevents friction plate burnout in case the speed sensor fails to detect speed; this time can be set as needed, but 1 second is preferred in this embodiment), the proportional valve continues to open to its maximum within 1 second (third predetermined time), allowing the pressure to rise to the working pressure within 1 second. Simultaneously, the difference between the clutch input speed and clutch output speed (i.e., the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2) is detected and calculated. When the forward electro-hydraulic proportional valve linearly opens to its maximum, if the detected speed difference is less than 20-30 revolutions per minute (predetermined speed), it directly opens to its maximum within 0.1 seconds (third predetermined time). This setting further reduces clutch slippage time, enabling rapid and smooth starts under different loads.

[0080] In this embodiment and some other embodiments, the target clutch is the reverse clutch KR, and the control process for changing the forward direction to the reverse direction includes the following steps:

[0081] C1, Control Unit A1 responds to the reversing request signal sent by the steering handle, controls the reverse electro-hydraulic proportional valve K2 to open its valve port to the third predetermined opening degree within the fourth predetermined time, so as to quickly fill the hydraulic cylinder of the reverse clutch KR with oil, eliminate the piston clearance, and make the friction plate initially contact. At the same time, it controls the forward electro-hydraulic proportional valve K1 of the forward clutch KV to linearly reduce its valve port opening degree.

[0082] C2. When the vehicle speed obtained by the front / rear axle input speed sensor n3 is less than the second predetermined speed, the forward clutch KV is fully disengaged, and the valve port of the reverse electro-hydraulic proportional valve K2 is opened to the fourth predetermined opening degree, so that the pressure of the reverse electro-hydraulic proportional valve K2 is maintained at the third predetermined pressure, so that the friction plate is in a slipping state and begins to transmit torque.

[0083] C3. Close the forward electro-hydraulic proportional valve K1, and open the valve port of the reverse electro-hydraulic proportional valve K2 at the second linear speed;

[0084] C4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the reverse electro-hydraulic proportional valve K2 will be directly opened to the maximum within the sixth predetermined time.

[0085] In this embodiment, the control process for changing from forward to reverse direction specifically includes the following steps: Receiving a reversing command: Control unit A1 receives a reversing request signal from the operator (switching from forward F to reverse R). The controller sends a command to the reverse electro-hydraulic proportional valve K2, causing its valve port to open to a third predetermined opening degree within a fourth predetermined time, quickly filling the clutch cylinder with oil, eliminating piston clearance, and allowing the friction plates to initially contact but not yet transmit large torque. At the same time, the controller sends a command to the forward electro-hydraulic proportional valve K1, causing the opening degree of the forward electro-hydraulic proportional valve K1 to decrease linearly, thereby reducing the forward gear pressure and smoothly reducing the transmitted torque. Then, based on the vehicle forward speed obtained from the front / rear axle input speed sensor n3, the speed is reduced to 3 km / h (second predetermined speed). The following steps are performed: within the fifth predetermined time, the forward electro-hydraulic proportional valve K1 is closed to fully disengage the forward clutch KV, and the valve port of the reverse electro-hydraulic proportional valve K2 is opened to the fourth predetermined opening degree, so that the reverse clutch pressure is maintained at 0.2-0.25 MPa (the third predetermined pressure), so that the friction plate is in a slipping state and begins to transmit torque. When the vehicle reverse speed obtained by the front / rear axle input speed sensor n3 is greater than the third predetermined speed, the valve port of the reverse electro-hydraulic proportional valve K2 is opened at the second linear speed. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than 20-30 revolutions (predetermined speed), the valve port of the reverse electro-hydraulic proportional valve K2 is directly opened to the maximum within 0.1 seconds (the sixth predetermined time).

[0086] Taking the power steering control logic in 2nd gear standard mode as an example, refer to... Figure 5In the diagram, X-axis represents time (in seconds), Y-axis represents gear pressure (in MPa), L1 represents the engine speed being limited to 1200 rpm, L2 represents the vehicle speed obtained by the front / rear axle input speed sensor n3 being less than 3 km / h, L3 represents the reverse gear speed being increased to 0.2 km / h, M1 is the pressure curve of the forward electro-hydraulic proportional valve K1, and M2 is the pressure curve of the reverse electro-hydraulic proportional valve K2. Upon receiving the reversing command, the forward electro-hydraulic proportional valve K1 linearly decreases its opening to 0.2 MPa within 0.3 seconds, with the friction plates in a state of only contact but not transmitting high torque. Simultaneously, the reverse electro-hydraulic proportional valve K2 opens its valve port to the third predetermined opening within 0.2 seconds (the fourth predetermined time), rapidly filling the clutch cylinder with oil to eliminate piston clearance, raising the reversing clutch KR to 0.15 MPa, and simultaneously limiting the engine's maximum speed to 1200 rpm, using engine drag for rapid braking. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is less than 3 km / h (the second predetermined speed), the forward electro-hydraulic proportional valve closes within 0.1 seconds. Simultaneously, for 0.1 seconds, the reverse electro-hydraulic proportional valve K2 continues to pressurize, maintaining the reverse clutch KR pressure at 0.22 MPa (the third predetermined pressure). This keeps the friction plates in a slipping state and begins to transmit torque. When the tractor's reverse speed reaches 0.2 km / h (the third predetermined speed), the valve of the reverse electro-hydraulic proportional valve K2 opens at the second linear speed, synchronizing the difference between the clutch input speed and the clutch output speed. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than 20 revolutions, the valve of the reverse electro-hydraulic proportional valve K2 is opened directly to its maximum within 0.1 seconds (the sixth predetermined time), fully engaging the clutch. This setting further reduces clutch slippage time, enabling rapid and smooth reversing under different loads.

[0087] In this embodiment, the switching time knob can be adjusted to provide three modes: standard, fast, and slow. Fast power switching mode: Based on the standard mode, the overall pressure curve increases by 0.2 MPa. Slow power switching mode: Based on the standard mode, the overall pressure curve decreases by 0.1 MPa.

[0088] In this embodiment and some other embodiments, the target clutch is the forward clutch KV, and the control process for changing from reverse direction to forward direction includes the following steps:

[0089] D1. Control unit A1 responds to the reversing request signal sent by the steering handle and controls the forward electro-hydraulic proportional valve K1 to open its valve port to the fifth predetermined opening degree within the seventh predetermined time to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plate initially contact. At the same time, it controls the reverse electro-hydraulic proportional valve K2 of the reverse clutch KR to linearly reduce its valve port opening degree.

[0090] D2. When the reverse speed of the vehicle obtained by the front / rear axle input speed sensor n3 is less than the fourth predetermined speed, the reverse electro-hydraulic proportional valve K2 is closed within the eighth predetermined time to completely disengage the reverse clutch KR, and the valve port of the forward electro-hydraulic proportional valve K1 is controlled to open to the sixth predetermined opening degree, so that the pressure of the forward electro-hydraulic proportional valve K1 is maintained at the fourth predetermined pressure, so that the friction plate is in a slipping state and begins to transmit torque.

[0091] D3. When the vehicle forward speed obtained from the front / rear axle input speed sensor n3 is greater than the fifth predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 is opened at the third linear speed.

[0092] D4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 will be directly opened to the maximum within the ninth predetermined time.

[0093] After the controller receives the reversing command, the reverse electro-hydraulic proportional valve K2 linearly decreases its opening to 0.2 MPa within 0.3 seconds, with the friction plates in a state of only contact but not transmitting large torque. Simultaneously, the forward electro-hydraulic proportional valve K1 opens its valve port to the fifth predetermined opening within 0.2 seconds (the seventh predetermined time), rapidly filling the clutch cylinder with oil to eliminate piston clearance, raising the forward clutch KV to 0.15 MPa, and simultaneously limiting the engine's maximum speed to 1200 rpm, using engine drag for rapid braking. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is less than 3 km / h (the fourth predetermined speed), the reverse electro-hydraulic proportional valve K2 closes within 0.1 seconds (the eighth predetermined time), and simultaneously, the forward electro-hydraulic proportional valve K1 continues to close within 0.1 seconds. The pressure continues to increase, controlling the opening of the forward electro-hydraulic proportional valve K1 to the sixth predetermined opening degree, maintaining the forward clutch KV pressure at 0.2-0.25 MPa (fourth predetermined pressure), preferably 0.22 MPa, so that the friction plates are in a slipping state and begin to transmit torque. When the tractor's reverse speed reaches 0.2 km / h (fifth predetermined speed), the forward electro-hydraulic proportional valve K1 is opened at the third linear speed, synchronizing the difference between the clutch input speed and the clutch output speed. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than 20-30 revolutions (predetermined speed), the forward electro-hydraulic proportional valve K1 is opened directly to its maximum within 0.1 seconds (ninth predetermined time), allowing the clutch to fully engage. This reduces clutch slippage time and enables rapid and smooth reversing under different loads.

[0094] In this embodiment, the switching time knob can be adjusted to provide three modes: standard, fast, and slow. Fast power switching mode: Based on the standard mode, the overall pressure curve increases by 0.2 MPa. Slow power switching mode: Based on the standard mode, the overall pressure curve decreases by 0.1 MPa.

[0095] In this embodiment, the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is calculated by simultaneously sampling every 100ms-200ms and calculating the speed difference. This method is applicable to clutch slippage judgment during starting, running, and reversing operations. The inventors discovered that the data obtained from the simultaneous, uninterrupted sampling of the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 deviates significantly from the actual speed difference. When the sampling is set to be performed simultaneously every 100ms-200ms, the sampled data is very close to the actual speed difference. This sampling method can more accurately reflect the actual speed difference, thereby making the operation time of the electro-hydraulic proportional valve more accurate.

[0096] In this embodiment, during operation, when the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is greater than 30-100 revolutions and lasts for 700ms-1.5s, the target clutch is quickly disengaged to protect the clutch.

[0097] In this embodiment, the value of the pre-charge pressure used to eliminate piston clearance during start-up and gear shifting is dynamically determined based on multiple parameters including clutch oil temperature, engine load, and the current gear.

[0098] In this embodiment, during tractor operation, the rotational speeds of gear Z2 and gear Z12 are sampled in real time, and the difference between the clutch input and output speeds is calculated in real time. Based on different gears (the current vehicle operating gear is obtained by calculating the rotational speeds of gears Z1 and Z31), vehicle speed, load, and operating conditions, it is determined whether the clutch is in a slipping state, thereby achieving the purpose of protecting the clutch and detecting clutch malfunctions. When a slipping state is detected, the electro-hydraulic proportional valve is actively closed, forcibly disengaging the clutch, and a fault message is sent to the vehicle.

[0099] If the speed sensor of gear Z12 malfunctions, the tractor will be unable to operate normally or move. In this embodiment, the sensor signal is checked by sampling the clutch pedal signal and the steering handle signal to determine if the sensor signal is blocked. After the speed sensor is replaced, the difference between the clutch input speed and the clutch output speed is automatically restored. The specific blocking method is as follows: the clutch pedal signal is greater than 3.8V, and the steering handle is switched back and forth between forward and neutral more than 15 times within 30 seconds for the blocking function to take effect.

[0100] In this embodiment, during operation, the tractor calculates the gearbox gear and vehicle speed in real time, and samples the engine speed and throttle position to determine the current load condition of the vehicle. When the engine speed decreases significantly due to increased resistance, and the main pressure is detected to be below 0.6 MPa, the electro-hydraulic proportional valve will be actively closed, forcibly disengaging the clutch.

[0101] In this embodiment, to adapt to the load characteristics of different agricultural implements and prevent engine stalling, the tractor's power take-off shaft (PTO) has intelligent boost control and safety linkage functions:

[0102] Boost control: When the transmission controller receives the PTO start command, the system will execute a precisely calibrated multi-stage boost curve: first, it will quickly build up the initial pressure within 0.3 seconds, then increase the pressure at a gentler slope for 0.5 seconds to smoothly connect the load, and finally quickly rise to the preset working pressure.

[0103] Safety linkage: The system works in deep coordination with the rear lifting mechanism. During PTO operation, if the implement is detected to have been raised to the predetermined safe height, the control unit A1 will actively disengage the PTO clutch, thereby effectively avoiding power waste and mechanism interference, and ensuring operational safety.

[0104] According to actual test results, the power reversing control method of this embodiment can be adapted to a transmission system with 12 forward gears and 12 reverse gears, achieving fast and smooth start-up and reversing. The entire start-up time is guaranteed to be completed within 2-3.5 seconds. When the tractor speed is below 5 km / h, the reversing can be completed within 3-4 seconds. When the tractor speed is below 10 km / h, the reversing can be completed within 5-6 seconds. Compared with the start-up and reversing method without speed sensor feedback, it can save 10%-30% of the time, improve work efficiency, and protect the friction plates, extending the service life of the friction plates by more than 400 hours.

[0105] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A transmission system for a tractor, characterized in that, include: Control unit A1, transmission unit and hydraulic unit: The transmission unit includes an input component, a reversing component, a shifting component, a front axle output component, and a rear axle output component. The input component includes a transmission input shaft (1) and a first gear Z1 and a second gear Z2 fixed on the transmission input shaft (1). The first gear Z1 and the second gear Z2 are coaxially arranged and rotate synchronously. The reversing component includes a clutch output shaft (2) and a fourth gear Z4 and a fifth gear Z5 loosely fitted on the clutch output shaft (2). The fourth gear Z4 meshes with the sixth gear Z6 for transmission, the sixth gear Z6 meshes with the first gear Z1 for transmission, and the fifth gear Z5 meshes with the second gear Z2 for transmission. The fourth gear Z4 engages or disengages with the clutch output shaft (2) through the reversing clutch KR, and the fifth gear Z5 engages with the clutch output shaft (2) through the forward clutch KV. 2) Engage or disengage, the clutch output shaft (2) is connected to the shifting component for transmission, the shifting component changes the transmission ratio by switching different gear combinations, the input shaft (4) of the rear axle output component is fixedly connected to the output shaft (3) of the shifting component or integrally formed, the twenty-eighth gear Z28 is fixedly connected to the output shaft (3) of the shifting component, the twenty-eighth gear Z28 is connected to the input shaft (5) of the front axle output component for transmission, the transmission unit also includes a transmission input shaft speed sensor n1 for detecting the speed of the transmission input shaft (1), a clutch output shaft speed sensor n2 for detecting the speed of the clutch output shaft (2), and a front axle / rear axle input speed sensor n3 for detecting the speed of the input shaft (5) of the front axle output component or the speed of the input shaft (4) of the rear axle output component; The hydraulic unit includes a forward electro-hydraulic proportional valve K1 and a reverse electro-hydraulic proportional valve K2. The oil inlet of the forward electro-hydraulic proportional valve K1 is connected to the oil tank, the working oil port of the forward electro-hydraulic proportional valve K1 is connected to the oil chamber of the forward clutch KV, the oil inlet of the reverse electro-hydraulic proportional valve K2 is connected to the main oil circuit (8), and the working oil port of the reverse electro-hydraulic proportional valve K2 is connected to the oil chamber of the reverse clutch KR. Control unit A1 is electrically connected to the steering handle, drive input shaft speed sensor n1, clutch output shaft speed sensor n2, front / rear axle input speed sensor n3, forward electro-hydraulic proportional valve K1, and reverse electro-hydraulic proportional valve K2, respectively. Control unit A1 is configured to receive signals sent by the steering handle, drive input shaft speed sensor n1, clutch output shaft speed sensor n2, and front / rear axle input speed sensor n3 in the transmission unit, and to send control signals to the forward electro-hydraulic proportional valve K1 and reverse electro-hydraulic proportional valve K2 in the hydraulic unit in response to the reversing request signal sent by the steering handle.

2. The transmission system of a tractor as described in claim 1, characterized in that, In the transmission unit, the transmission input shaft (1) is connected or disconnected from the PTO device through the PTO clutch KP; In the hydraulic unit, the oil tank is connected to the first oil pump (11), which is used to draw the oil in the oil tank to the main oil circuit (8). The input end of the first relief valve (6) is connected to the main oil circuit (8), and the output end of the first relief valve (6) is connected to the lubrication circuit. The input end of the second relief valve (7) is connected to the main oil circuit (8), and the output end of the second relief valve (7) is connected to the PTO valve group through the first oil circuit (9). The output end of the second relief valve (7) is connected to the forward electro-hydraulic proportional valve K1 and the reverse electro-hydraulic proportional valve K2 through the second oil circuit (10). The PTO valve group is used to control the PTO clutch KP.

3. The transmission system of a tractor as described in claim 2, characterized in that, The PTO valve assembly includes a PTO clutch electro-hydraulic proportional valve K3 and a PTO clutch solenoid valve K4. The output end of the second relief valve (7) is connected to the input port of the PTO clutch electro-hydraulic proportional valve K3 through the first oil circuit (9). The working port of the PTO clutch electro-hydraulic proportional valve K3 is connected to the inlet port of the PTO clutch solenoid valve K4. The working port of the PTO clutch solenoid valve K4 is connected to the PTO clutch KP. The control unit A1 is electrically connected to the PTO clutch electro-hydraulic proportional valve K3 and the PTO clutch solenoid valve K4.

4. The transmission system of a tractor as described in claim 3, characterized in that, The forward electro-hydraulic proportional valve K1 is equipped with a forward pressure sensor n5, the reverse electro-hydraulic proportional valve K2 is equipped with a reverse pressure sensor n6, and the PTO clutch electro-hydraulic proportional valve K3 is equipped with a PTO pressure sensor. The forward pressure sensor n5, the reverse pressure sensor n6, and the PTO pressure sensor are electrically connected to the control unit A1.

5. A power reversing control method, applied to the transmission system of a tractor as described in any one of claims 1-4, characterized in that, Includes the following steps: S1, Control unit A1 responds to the reversing request signal sent by the steering handle, controls the electro-hydraulic proportional valve corresponding to the target clutch to open its valve port to a predetermined opening degree within a predetermined time A, so as to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plates initially contact. S2. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is greater than the predetermined speed, the valve port of the electro-hydraulic proportional valve corresponding to the target clutch is opened at a linear speed. S3. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the electro-hydraulic proportional valve corresponding to the target clutch is directly opened to the maximum within the predetermined time B.

6. The power commutation control method as described in claim 5, characterized in that, The target clutch is the forward clutch KV, and the starting control process includes the following steps: B1. In response to the reversing request signal sent by the steering handle, the control unit A1 controls the forward electro-hydraulic proportional valve K1 to open its valve port to the first predetermined opening degree within a first predetermined time, so as to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plates initially contact. B2. When the oil supply pressure of the forward electro-hydraulic proportional valve K1 reaches the first predetermined pressure, the forward electro-hydraulic proportional valve K1 is controlled to open to the second predetermined degree within a second predetermined time, so that its oil supply pressure rises linearly to the second predetermined pressure within the second predetermined time. B3. When the vehicle speed obtained from the front / rear axle input speed sensor n3 is greater than the first predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 is opened at the first linear speed. B4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 will be directly opened to the maximum within the third predetermined time.

7. The power commutation control method as described in claim 5, characterized in that, The target clutch is the reverse clutch KR. The control process for changing from forward to reverse direction includes the following steps: C1, Control Unit A1 responds to the reversing request signal sent by the steering handle, controls the reverse electro-hydraulic proportional valve K2 to open its valve port to the third predetermined opening degree within the fourth predetermined time, so as to quickly fill the hydraulic cylinder of the reverse clutch KR with oil, eliminate the piston clearance, and make the friction plate initially contact. At the same time, it controls the forward electro-hydraulic proportional valve K1 of the forward clutch KV to linearly reduce its valve port opening degree. C2. When the vehicle forward speed obtained from the front / rear axle input speed sensor n3 is less than the second predetermined speed, the forward electro-hydraulic proportional valve K1 is closed within the fifth predetermined time to completely disengage the forward clutch KV, and the valve port of the reverse electro-hydraulic proportional valve K2 is controlled to open to the fourth predetermined opening degree, so that the pressure of the reverse electro-hydraulic proportional valve K2 is maintained at the third predetermined pressure, so that the friction plate is in a slipping state and begins to transmit torque. C3. When the vehicle's reverse speed, obtained from the front / rear axle input speed sensor n3, is greater than the third predetermined speed, the valve port of the reverse gear electro-hydraulic proportional valve K2 is opened at the second linear speed. C4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the reverse electro-hydraulic proportional valve K2 will be directly opened to the maximum within the sixth predetermined time.

8. The power commutation control method as described in claim 5, characterized in that, The target clutch is the forward clutch KV. The control process for changing from reverse direction to forward direction includes the following steps: D1. Control unit A1 responds to the reversing request signal sent by the steering handle and controls the forward electro-hydraulic proportional valve K1 to open its valve port to the fifth predetermined opening degree within the seventh predetermined time to quickly fill the forward clutch KV cylinder with oil, eliminate the piston clearance, and make the friction plate initially contact. At the same time, it controls the reverse electro-hydraulic proportional valve K2 of the reverse clutch KR to linearly reduce its valve port opening degree. D2. When the reverse speed of the vehicle obtained by the front / rear axle input speed sensor n3 is less than the fourth predetermined speed, the reverse electro-hydraulic proportional valve K2 is closed within the eighth predetermined time to completely disengage the reverse clutch KR, and the valve port of the forward electro-hydraulic proportional valve K1 is controlled to open to the sixth predetermined opening degree, so that the pressure of the forward electro-hydraulic proportional valve K1 is maintained at the fourth predetermined pressure, so that the friction plate is in a slipping state and begins to transmit torque. D3. When the vehicle forward speed obtained from the front / rear axle input speed sensor n3 is greater than the fifth predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 is opened at the third linear speed. D4. When the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is less than the predetermined speed, the valve port of the forward electro-hydraulic proportional valve K1 will be directly opened to the maximum within the ninth predetermined time.

9. The power commutation control method as described in claim 5, characterized in that, The speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is calculated by sampling simultaneously every 100ms-200ms and calculating the speed difference.

10. The power commutation control method as described in claim 5, characterized in that, During operation, if the speed difference between the transmission input shaft speed sensor n1 and the clutch output shaft speed sensor n2 is greater than 30-100 revolutions and lasts for 700ms-1.5s, the target clutch will be quickly disengaged to protect the clutch.

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