A tractor electric drive travel system and control method thereof

Abstract

The present invention provides an electric drive travel system of a tractor and a control method thereof, comprising a front steering drive axle assembly, a rear drive axle assembly, a travel gearbox assembly, a travel drive motor, a first shift motor and a second shift motor; the travel gearbox assembly selectively outputs power of two gears to the front steering drive axle assembly, and the travel gearbox assembly outputs power of one gear to the rear drive axle assembly, the first shift motor is used to switch the drive gear of the front steering drive axle assembly, and the second shift motor is used to control the engagement or separation of the rear drive axle assembly and the transmission assembly; the travel transmission assembly comprises a four-wheel drive clutch, and the four-wheel drive clutch is used to control the engagement or separation of the front steering drive axle assembly and the transmission assembly. The present invention adopts an electric drive structure arrangement, has a compact structure, and is highly efficient, and power output control can realize precise control of the motor and fine distribution of power output.

Description

Technical Field

[0001] The invention belongs to the technical field of tractors, and in particular is an electric drive travel system for a tractor and a control method thereof. Background Art

[0002] The existing tractor travel system adopts structures such as an engine, a transmission and a clutch to achieve front and rear axle drive travel. For example, a four-wheel drive system of a tractor disclosed in Chinese patent CN205890549U includes a transmission device, a rear axle differential, a rear drive shaft, a gearbox, a front drive shaft and a front axle differential. The gearbox is connected to the rear axle differential through the rear drive shaft, the rear axle differential is connected to the rear axle through the transmission device, the gearbox is integrated with the front axle, the front axle differential is located inside the gearbox and is connected to the gearbox through the front drive shaft, and the front axle differential is connected to the front axle.

[0003] Another example is a novel front-rear drive tractor transmission system disclosed in Chinese patent CN20302218730U, which includes: a power component, which includes an engine and a transmission box, the engine transmits power to the transmission box through a conveyor belt, and the transmission box transmits power to the gearbox through a main drive shaft; a transmission component, which includes a front drive shaft and a rear drive shaft connected to the gearbox, the front drive shaft drives the front wheels to rotate through the front axle, and the rear drive shaft drives the rear wheels to rotate through the rear axle, a front main reducer is installed in the front axle, and a rear main reducer is installed in the rear axle; wherein the gear ratio of the front main reducer and the rear main reducer is equal to the radius ratio of the front wheels and the rear wheels, a front and rear drive separation operating lever is provided in the gearbox, and the front drive shaft and the rear drive shaft are both connected to the front and rear drive separation operating lever.

[0004] The above structure has some problems: when changing gears, the engine and gearbox need to be disconnected, resulting in power interruption and affecting the stability of use; the mechanical shift tractor operator has high labor intensity, and the wet clutch of the power shift tractor has harsh use conditions and limited gears; the change in engine speed causes flow fluctuations, affecting the quality and efficiency of the operation. In addition, there are two energy conversions in the power transmission process, mechanical energy is converted into the internal energy of the liquid, and then converted into mechanical energy again, and the energy conversion efficiency is low; the mechanical brake is used very frequently and wears quickly; the traditional mechanical transmission system has a relatively strict relationship between the spatial position of the input and output shafts; the engine output torque and speed fluctuate greatly, which has a great impact on the transmission system. Summary of the invention

[0005] The present invention provides a tractor electric drive travel system and a control method thereof, which adopts an electric drive structure arrangement, has a compact structure and high efficiency. The power output control can realize the precise control of the motor and fine distribution of power output.

[0006] A tractor electric drive travel system comprises a front steering drive axle assembly, a rear drive axle assembly, a travel gearbox assembly, a travel drive motor, a first gear shifting motor and a second gear shifting motor; the travel gearbox assembly selectively outputs two gears of power to the front steering drive axle assembly, and the travel gearbox assembly outputs one gear of power to the rear drive axle assembly, the first gear shifting motor is used to switch the drive gear of the front steering drive axle assembly, and the second gear shifting motor is used to control the engagement or disengagement of the rear drive axle assembly and the travel gearbox assembly; the travel gearbox assembly comprises a four-wheel drive clutch, and the four-wheel drive clutch is used to control the engagement or disengagement of the front steering drive axle assembly and the travel gearbox assembly.

[0007] The present invention adopts the mature existing motor technology, simplifies the structure, reduces the composition of parts, and the motor drive can achieve stepless speed change and reverse operation to meet the working conditions. It is easy to operate and simple to control.

[0008] The gear shifting motor is used for gear shifting, and the power is finely controlled and distributed to achieve efficient transmission.

[0009] The present invention adopts three gears to engage the motor drive, utilizes the motor's stepless speed regulation and reversing characteristics, reduces the gear settings, greatly reduces the transmission assembly, and reduces the volume and cost.

[0010] The gear shifting is performed by a shifting motor, which has a simple structure, precise control, fast shifting speed, and reduced power interruption during gear shifting. The power output control can achieve precise control of the motor and fine distribution of power output.

[0011] Preferably, the travel gearbox assembly includes a first shaft, a second shaft, a third shaft and a front output shaft; also includes an input gear arranged on the first shaft, and the first shaft is connected to a travel drive motor; also includes a first gear driving gear, a first shifting mechanism, a second gear driving gear, and a third gear driving gear arranged in sequence on the second shaft, and also includes a first gear driven gear, a front drive driving gear, a second gear driven gear, and a third gear driven gear arranged in sequence on the third shaft; the front drive driving gear and the second gear driven gear are both fixedly arranged on the third shaft.

[0012] The rear end of the third shaft is connected to the rear drive axle assembly, and a second shift mechanism connected to the second shift motor is provided on the third shaft. The third gear driven gear is sleeved on the third shaft, and the second shift mechanism selectively engages or disengages with the third gear driven gear; when the third gear is needed, the second shift mechanism is used to fixedly connect the third gear driven gear and the third shaft to realize direct drive of the third gear.

[0013] A front drive driven gear is sleeved on the front output shaft, and a four-wheel drive clutch is arranged on the front output shaft to control the engagement or separation of the front drive driven gear and the front output shaft. When in the first gear or the second gear, the four-wheel drive clutch fixedly connects the front drive driven gear and the front output shaft.

[0014] In the present invention, the first gear driving gear cooperates with the first gear driven gear, the second gear driving gear cooperates with the second gear driven gear, and the input gear cooperates with the third gear driven gear, thereby achieving gear ratio travel in three gears, corresponding to different speed ranges, and ensuring that each power source can work in a high-efficiency area.

[0015] Preferably, the present invention also includes a speed pump assembly for driving the four-wheel drive clutch, and the speed pump assembly is used to drive the four-wheel drive clutch. Specifically, the speed pump assembly includes a speed pump, a speed pump drive motor and a solenoid valve. The speed pump drive motor is used to drive the speed pump, and the solenoid valve is used to control the oil circuit of the four-wheel drive clutch.

[0016] Preferably, the first axis, the second axis and the third axis are arranged in parallel, which has a simple structure, is convenient for gear arrangement and saves space.

[0017] Preferably, the first gear shifting motor, the second gear shifting motor and the travel drive motor are all arranged outside the housing of the travel gearbox assembly. The structure of the external control motor is adopted, which is convenient for maintenance and disassembly and low in cost.

[0018] Preferably, it also includes a front transmission shaft and a rear transmission shaft, both of which are universal shaft structures, one end of the front transmission shaft is connected to the front output shaft and the other end is connected to the front steering drive axle assembly, and one end of the rear transmission shaft is connected to the third shaft and the other end is connected to the rear drive axle assembly. The universal transmission shaft can effectively balance the unbalanced force in the transmission process, making the transmission process more stable and reducing the generation of vibration and noise.

[0019] The present invention also provides a control method for a tractor electric drive travel system, which adopts the above-mentioned tractor electric drive travel system and comprises the following steps:

[0020] Step S1: The whole machine is started, the first shift motor is controlled to switch the gear to the first gear, and the four-wheel drive clutch is controlled to engage; at this time, it is in the first gear four-wheel drive mode driving operation mode.

[0021] Step S2: Real-time acquisition of vehicle speed. When the vehicle speed is less than the first threshold V1, the state of step S1 is maintained. When the first threshold V 1< Vehicle speed ≤ The second threshold V2, enters step S3; when the second threshold V 2< Vehicle speed, go to step 4.

[0022] Step S3: Control the first shift motor to switch the gear to the second gear, control the four-wheel drive clutch to engage, and return to step S2; at this time, it is in the second gear four-wheel drive mode driving operation mode.

[0023] Step S4: Control the second shift motor to engage the third gear, and the solenoid valve controls the four-wheel drive clutch to disconnect, and return to step S2. At this time, it is in the three-gear rear-wheel drive mode driving operation mode, and the power transmission path is: travel drive motor, first shaft, input gear, third gear driving gear, third gear driven gear, second shift mechanism, third shaft, rear drive shaft, rear drive axle assembly. At this time, the four-wheel drive clutch is disconnected, the first gear shift mechanism is in the neutral position, and there is no power output to the front axle.

[0024] The driving control method of the present invention adopts a four-wheel drive mode in the starting and medium-speed areas, and has a large power to meet acceleration requirements. In the high-speed stage, a rear-wheel drive mode is adopted and the power is reduced, thereby reducing energy consumption.

[0025] The first threshold value V1 of the present invention is 15 km / h, and the second threshold value V2 is 23 km / h.

[0026] In the present invention, the output power of the driving motor in step S1 is greater than the output power of the driving motor in step S3, and the output power of the driving motor in step S2 is greater than the output power of the driving motor in step S4. In terms of control method: the present invention adopts the four-wheel drive mode in the starting and medium-speed areas, and the power is large to meet the acceleration requirements. In the high-speed stage, the rear-wheel drive mode is adopted and the power is reduced, thereby reducing energy consumption.

[0027] In the present invention, the vehicle speed in step S2 is calculated by obtaining the speed signal of the gear in the running gearbox assembly. The present invention also includes a speed sensor arranged at the outer periphery of the first gear driven gear, which is installed at the edge of the gearbox assembly for easy installation and removal. By obtaining the speed sensor, a real-time vehicle speed signal is calculated according to the transmission ratio, which has a simple structure and low cost.

[0028] The step S1 and step S2 of the present invention also include a step in which the speed change pump assembly drives the four-wheel drive clutch 7 to work and controls the engagement of the front steering drive axle assembly and the gearbox assembly. In this step, the front output shaft is connected to the front drive driven gear to output power to the front transmission shaft.

[0029] In the present invention, the control system also includes an accelerator pedal, a VCU vehicle control unit, an MCU drive motor controller, a first TCU controller, and a second TCU controller, wherein the VCU vehicle control unit is electrically connected to the accelerator pedal, a speed sensor, an MCU drive motor controller, a first TCU controller, a second TCU controller, a speed change pump, and a solenoid valve;

[0030] In step S1 of the present invention, the VCU vehicle control unit obtains the accelerator pedal signal and the speed sensor signal and then outputs an instruction, controls the MCU to drive the motor controller to start the travel drive motor, controls the first TCU controller to drive the first shift motor to drive the first shift mechanism to engage the first gear, and the VCU vehicle control unit controls the speed change pump drive motor and the solenoid valve to engage the four-wheel drive clutch to enter the first gear four-wheel drive mode;

[0031] In step S3 of the present invention, the VCU vehicle control unit obtains the accelerator pedal signal and the speed sensor signal and then outputs an instruction to control the first TCU controller to drive the first shift motor to drive the first shift mechanism to engage the second gear, and the VCU vehicle control unit controls the transmission pump drive motor and the solenoid valve to engage the four-wheel drive clutch to enter the second gear four-wheel drive mode;

[0032] In step S4 of the present invention, the VCU vehicle control unit issues an instruction to control the separation of the four-wheel drive clutch in the solenoid valve, and controls the separation of the front steering drive axle assembly and the transmission assembly. In this step, the front output shaft and the front drive driven gear are powered separately, and the power output to the front transmission shaft is interrupted.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] Existing motor technology is mature and widely used. In addition, its simplified structure reduces the number of parts and components, resulting in lower costs.

[0035] Operation: It adopts dynamic motor for operation, with quick gear shifting, reducing the negative impact caused by power interruption, simplified structure, precise control, and motor drive can achieve stepless speed change and reverse operation to meet the working conditions. It is easy to operate and simple to control.

[0036] In terms of performance, compared with the existing technology, since the motor has its own speed regulation capability, the gear setting can be reduced to only 3 gears, avoiding the power interruption caused by gear changes in traditional transmissions, and the transmission efficiency can be improved.

[0037] Functional aspect: The electric drive arrangement can ensure that each power source can work in the high-efficiency zone, and the motor can be used to realize the recycling of braking energy, reducing the wear of the braking system in the prior art.

[0038] In terms of control method: the present invention adopts the four-wheel drive mode in the starting and medium-speed areas, and has a large power to meet the acceleration requirements. In the high-speed stage, the rear-wheel drive mode is adopted and the power is reduced to reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The utility model is a schematic diagram of the internal structure of the electric drive travel system of the tractor described in the present invention.

[0040] Figure 2 The present invention discloses an appearance structure diagram of a tractor electric drive travel system.

[0041] Figure 3 It is an enlarged structural diagram of the travel gearbox assembly described in the present invention.

[0042] Figure 4 It is the vehicle speed and gear relationship mapping diagram described in the present invention.

[0043] Figure 5 The present invention discloses a control step flow chart of a control method for a tractor electric drive travel system.

[0044] In the figure: 1-front steering drive axle assembly, 2-rear drive axle assembly, 3-travel gearbox assembly, 301-first shaft, 302-second shaft, 303-third shaft, 304-front output shaft; 301-first shaft, 305-third gear driving gear, 306-third gear driving gear, 307-first gear driving gear, 308-first gear driven gear, 309-first gear shifting mechanism, 310-second gear driving gear, 311-second gear driven gear, 312-front drive driving gear, 313-front drive driven gear, 314- 14-second gear shifting mechanism, 315-third gear driven gear, 4-travel drive motor, 5-first gear shifting motor, 6-second gear shifting motor, 7-four-wheel drive clutch, 8-speed pump assembly, 801-speed pump, 802-speed pump drive motor, 803-solenoid valve, 9-front drive shaft, 10-rear drive shaft, 11-speed sensor, 12-accelerator pedal, 13-VCU vehicle control unit, 14-MCU drive motor controller, 15-first TCU controller, 16-second TCU controller. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0046] In the description of the present invention, it is necessary to understand that the terms "left", "right", "up", "down", "front", "back", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or structure referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0047] Embodiment 1:

[0048] like Figure 1 and Figure 2As shown, a tractor electric drive travel system includes a front steering drive axle assembly 1, a rear drive axle assembly 2, a travel gearbox assembly 3, a travel drive motor 4, a first gear shift motor 5 and a second gear shift motor 6; the travel gearbox assembly 3 selectively outputs two gears of power to the front steering drive axle assembly 1, and the travel gearbox assembly 3 outputs one gear of power to the rear drive axle assembly 2, the first gear shift motor 5 is used to switch the drive gear of the front steering drive axle assembly 1, and the second gear shift motor 6 is used to control the engagement or disengagement of the rear drive axle assembly 2 and the travel gearbox assembly 3; the travel gearbox assembly 3 includes a four-wheel drive clutch 7, and the four-wheel drive clutch 7 is used to control the engagement or disengagement of the front steering drive axle assembly 1 and the travel gearbox assembly 3.

[0049] like Figure 3 As shown, in this embodiment, the travel gearbox assembly 3 includes a first shaft 301, a second shaft 302, a third shaft 303 and a front output shaft 304; it also includes an input gear 305 arranged on the first shaft 301, and the first shaft 301 is connected to the travel drive motor 4; it also includes a first gear driving gear 307, a first shifting mechanism 309, a second gear driving gear 310, and a third gear driving gear 306 which are sequentially arranged on the second shaft 302, and it also includes a first gear driven gear 308, a front drive gear 306 which are sequentially arranged on the third shaft 303. 312, a second-gear driven gear 311, and a third-gear driven gear 315; the rear end of the third shaft 303 is connected to the rear drive axle assembly 2, and the third shaft 303 is provided with a second shift mechanism 314 connected to the second shift motor 6, and the second shift mechanism 314 selectively engages or disengages with the third-gear driven gear 315; the front output shaft 304 is provided with a front-drive driven gear 313, and the four-wheel drive clutch 7 is provided on the front output shaft 304 for controlling the engagement or disengagement of the front-drive driven gear 313 and the front output shaft 304.

[0050] like Figure 3 As shown, in this embodiment, the first gear driving gear 307 cooperates with the first gear driven gear 308, the second gear driving gear cooperates with the second gear driven gear, and the input gear cooperates with the third gear driven gear, thereby achieving 30 gear positions.

[0051] like Figure 3 As shown, in this embodiment, the first gear driving gear 307 and the second gear driving gear are both arranged in an idle sleeve on the second shaft 302, the front drive driving gear 312, the first gear driven gear 308 and the second gear driven gear are fixedly arranged on the third shaft 303, the front drive driven gear 313 is arranged in an idle sleeve on the front output shaft 304, and the first shift mechanism is fixedly arranged on the second shaft 302.

[0052] This embodiment also includes a variable speed pump assembly 8 for driving the four-wheel drive clutch 7, the variable speed pump assembly 8 includes a variable speed pump 801, a variable speed pump driving motor 802 and a solenoid valve 803, the variable speed pump driving motor 802 is used to drive the variable speed pump 801, and the solenoid valve 803 is used to control the on-off of the oil circuit of the four-wheel drive clutch 7. One end of the solenoid valve 803 is connected to the variable speed pump 801 and the other end is connected to the four-wheel drive clutch 7.

[0053] like Figure 3 As shown, in this embodiment, the first axis 301, the second axis 302, and the third axis 303 are arranged in parallel.

[0054] like Figure 1 and Figure 3 As shown, in this embodiment, the first gear shifting motor 5 , the second gear shifting motor 6 and the travel drive motor 4 are all arranged outside the housing of the travel gearbox assembly 3 .

[0055] like Figure 1 and Figure 2 As shown, this embodiment also includes a front drive shaft 9 and a rear drive shaft 10, both of which are universal shaft structures, one end of the front drive shaft 9 is connected to the front output shaft 304 and the other end is connected to the front steering drive axle assembly 1, and one end of the rear drive shaft 10 is connected to the third shaft 303 and the other end is connected to the rear drive axle assembly 2.

[0056] like Figure 3 As shown, the power transmission principle of this embodiment is:

[0057] When starting or at a low speed, first gear drive is adopted, and the first shifting motor 5 drives the first shifting mechanism 309 to be in the left position. The transmission route is: walking drive motor 4, first shaft 301, input gear 305, third gear driving gear 306, second shaft 302, first gear driving gear 307, first gear driven gear 308, third shaft 303. Thereafter, the power is divided into two lines, the first one is directly output to the rear transmission shaft 10 by the third shaft 303, and the other one is through the front drive driving gear 312, the front drive driven gear 313, the front output shaft 304, the front transmission shaft 9, and the front transmission drive axle assembly to realize front and rear wheel four-wheel drive.

[0058] When the speed is in the medium range, the second gear is used for driving, the first gear shifting motor 5 drives the first gear shifting mechanism 309 to the right position, and the transmission path of the second gear is similar to that of the first gear;

[0059] When the speed is in the high-speed area, the first shift motor 5 drives the first shift mechanism 309 to the neutral position, and the three-speed transmission is adopted. At this time, the second shift mechanism 314 is engaged, and the transmission route is: travel drive motor 4, first shaft 301, input gear 305, third-speed driving gear 306, third-speed driven gear 315, third shaft 303, rear transmission shaft 10, rear drive axle assembly 2.

[0060] Embodiment 2:

[0061] like Figure 5 As shown, a tractor electric drive travel control method adopts the tractor electric drive travel system in the above embodiment, comprising the following steps:

[0062] Step S1: The whole machine is started, the first shift motor 5 is controlled to switch the gear to the first gear, and the four-wheel drive clutch 7 is controlled to engage; at this time, it is in the first gear four-wheel drive mode driving operation mode. The transmission route is: travel drive motor 4, first shaft 301, input gear 305, third gear driving gear 306, second shaft 302, first gear driving gear 307, first gear driven gear 308, third shaft 303, and then the power is divided into two, the first is directly output from the third shaft 303 to the rear transmission shaft 10, and the other is through the front drive driving gear 312, front drive driven gear 313, front output shaft 304, front transmission shaft 9, and front transmission drive axle assembly.

[0063] Step S2: Acquire the vehicle speed in real time. When the vehicle speed is less than the first threshold value V1, maintain the state of step S1, that is, maintain the driving mode and gear state of step S1, that is, the first gear four-wheel drive mode; when the first threshold value V 1≤ Vehicle speed < The second threshold V2, enters step S3; when the second threshold V 2< Vehicle speed, go to step 4.

[0064] Step S3: Control the first shift motor 5 to switch the gear to the second gear, control the four-wheel drive clutch 7 to engage, and return to step S2; at this time, it is in the second gear four-wheel drive mode driving operation mode.

[0065] Step S4: Control the second shift motor 6 to engage the third gear, and the solenoid valve 803 controls the four-wheel drive clutch 7 to disconnect, and return to step S2. At this time, it is in the three-gear rear-wheel drive mode, and the power transmission path is: walking drive motor 4, first shaft 301, input gear 305, third-gear driving gear 306, third-gear driven gear 315, second shift mechanism 314, third shaft 303, rear drive shaft 10, rear drive axle assembly 2. At this time, the four-wheel drive clutch 7 is disconnected, the first gear shift mechanism is in the neutral position, and there is no power output from the front axle. The three-gear rear-wheel drive mode and low power output can reduce energy consumption.

[0066] In this embodiment, the first threshold V1 is 15 km / h, and the second threshold V2 is 23 km / h. The two speed thresholds constitute the low speed, medium speed and high speed areas of the corresponding tractor.

[0067] like Figure 4 As shown, in this embodiment, the output power in step S1 is greater than the output power in step S3, and the output power in step S3 is greater than the output power in step S4. As the speed increases, the acceleration demand of the tractor decreases, and the output power can be gradually reduced to reduce energy consumption. Specifically, in step S1, when the starting speed is lower than 10km / h, the travel drive motor outputs the traction power Pmax at full load, and adopts the first gear four-wheel drive mode to obtain better acceleration performance; the operating range in step 2 is between the first threshold V1 and the second threshold V2, and the traction power of the travel drive motor is gradually reduced; in step S4, the third gear rear-wheel drive mode is adopted. At this time, the speed is high and the acceleration demand is weakened, and low power output can be adopted to reduce energy consumption.

[0068] like Figure 3 As shown, in step S2 of this embodiment, the vehicle speed is calculated by obtaining the speed signal of the gear in the travel gearbox assembly 3. Specifically, in this embodiment, a speed sensor 11 is also provided at the outer periphery of the first gear driven gear 308, which is installed at the edge of the gearbox assembly for easy installation and removal. By obtaining the speed sensor 11, a real-time vehicle speed signal is calculated according to the transmission ratio, which has a simple structure and low cost.

[0069] like Figure 1 As shown, in this embodiment, the control system also includes an accelerator pedal 12, a VCU vehicle control unit 13, an MCU drive motor controller 14, a first TCU controller 15, and a second TCU controller 16. The VCU vehicle control unit 13 is electrically connected to the accelerator pedal 12, the speed sensor 11, the MCU drive motor controller 14, the first TCU controller 15, the second TCU controller 16, the variable speed pump 801 and the solenoid valve 803;

[0070] In this embodiment, the VCU vehicle control unit 13 controls the speed of the variable speed pump drive motor 802, and the VCU vehicle control unit 13 controls the oil circuit of the solenoid valve 803 to achieve the engagement or disengagement of the four-wheel drive clutch 7.

[0071] In step S1 of this embodiment, the VCU vehicle control unit 13 obtains the accelerator pedal 12 signal and the speed sensor 11 signal and then outputs a command, controls the MCU drive motor controller 14 to start the drive motor, controls the first TCU controller 15 to drive the first shift motor 5 to drive the first shift mechanism 309 to engage the first gear, and the VCU vehicle control unit 13 controls the speed change pump drive motor 802 and the solenoid valve 803 to engage the four-wheel drive clutch 7 to enter the first gear four-wheel drive mode;

[0072] In step S3 of this embodiment, the VCU vehicle control unit 13 obtains the accelerator pedal 12 signal and the speed sensor 11 signal and then outputs a command to control the first TCU controller 15 to drive the first shift motor 5 to drive the first shift mechanism 309 to engage the second gear, and the VCU vehicle control unit 13 controls the speed change pump drive motor 802 and the solenoid valve 803 to engage the four-wheel drive clutch 7 to enter the second gear four-wheel drive mode;

[0073] In step S4 of this embodiment, the VCU vehicle control unit 13 issues a command, the first shift motor 5 controls the first shift mechanism 309 to be in the middle position, i.e., the neutral position, controls the oil circuit of the solenoid valve 803 to realize the separation of the four-wheel drive clutch 7, and controls the separation of the front steering drive axle assembly 1 and the gearbox assembly 3. In this step, the front output shaft 304 and the front drive driven gear 313 are powered separately, and the power output to the front transmission shaft 9 is interrupted.

Claims

1. A tractor electric drive travel system, characterized in that The invention comprises a front steering drive axle assembly (1), a rear drive axle assembly (2), a travel gearbox assembly (3), a travel drive motor (4), a first gear shifting motor (5) and a second gear shifting motor (6); the travel gearbox assembly (3) selectively outputs power of two gears to the front steering drive axle assembly (1), and the travel gearbox assembly (3) outputs power of one gear to the rear drive axle assembly (2); the first gear shifting motor (5) is used to switch the drive gear of the front steering drive axle assembly (1), and the second gear shifting motor (6) is used to control the engagement or disengagement of the rear drive axle assembly (2) and the travel gearbox assembly (3); the travel gearbox assembly (3) comprises a four-wheel drive clutch (7), and the four-wheel drive clutch (7) is used to control the engagement or disengagement of the front steering drive axle assembly (1) and the travel gearbox assembly (3).

2. The electric drive travel system of a tractor according to claim 1, characterized in that: The travel gearbox assembly (3) comprises a first shaft (301), a second shaft (302), a third shaft (303) and a front output shaft (304); further comprises an input gear (305) arranged on the first shaft (301), the first shaft (301) being connected to a travel drive motor (4); further comprises a first gear driving gear (307), a first gear shifting mechanism (309), a second gear driving gear (310), and a third gear driving gear (306) arranged in sequence on the second shaft (302); further comprises a first gear driven gear (308), a front drive driving gear (312) and a third gear driving gear (306) arranged in sequence on the third shaft (303). ), a second gear driven gear (311), and a third gear driven gear (315); the rear end of the third shaft (303) is connected to the rear drive axle assembly (2); the third shaft (303) is provided with a second gear shifting mechanism (314) connected to the second gear shifting motor (6); the second gear shifting mechanism (314) selectively engages or disengages with the third gear driven gear (315); the front output shaft (304) is provided with a front drive driven gear (313); a four-wheel drive clutch (7) is provided on the front output shaft (304) for controlling the engagement or disengagement of the front drive driven gear (313) and the front output shaft (304).

3. The electric drive travel system of a tractor according to claim 2, characterized in that: The invention also includes a variable speed pump assembly (8) for driving the four-wheel drive clutch (7), wherein the variable speed pump assembly (8) includes a variable speed pump (801), a variable speed pump driving motor (802) and a solenoid valve (803), wherein the variable speed pump driving motor (802) is used to drive the variable speed pump (801), and the solenoid valve (803) is used to control the on-off of the oil circuit of the four-wheel drive clutch (7).

4. The electric drive travel system of a tractor according to claim 2, characterized in that: The first axis (301), the second axis (302), and the third axis (303) are arranged in parallel.

5. The electric drive travel system of a tractor according to claim 1, characterized in that: The first gear-shifting motor (5), the second gear-shifting motor (6) and the travel drive motor (4) are all arranged outside the housing of the travel gearbox assembly (3).

6. The electric drive travel system of a tractor according to claim 2, characterized in that The invention also comprises a front transmission shaft (9) and a rear transmission shaft (10), both of which are universal shaft structures, one end of the front transmission shaft (9) is connected to the front output shaft (304) and the other end is connected to the front steering drive axle assembly (1), and one end of the rear transmission shaft (10) is connected to the third shaft (303) and the other end is connected to the rear drive axle assembly (2).

7. A control method for a tractor electric drive travel system, using the tractor electric drive travel system according to any one of claims 2 to 6, characterized in that The steps include: Step S1: the whole machine is started, the first gear shifting motor (5) is controlled to switch the gear to the first gear, and the four-wheel drive clutch (7) is controlled to engage; Step S2: Real-time acquisition of vehicle speed. When the vehicle speed is less than the first threshold V1, the state of step S1 is maintained. When the first threshold V 1≤ Vehicle speed < When the first threshold V 2< Vehicle speed, go to step 4; Step S3: Control the first shift motor (5) to switch the gear to the second gear, control the four-wheel drive clutch (7) to engage, and return to step S2; Step S4: Control the second shift motor (6) to engage the third gear, and the solenoid valve (803) controls the four-wheel drive clutch (7) to disconnect, and return to step S2.

8. The control method of the electric drive travel system of a tractor according to claim 7, characterized in that: The first threshold V1 is 15km / h, and the second threshold V2 is 23km / h.

9. The control method of the electric drive travel system of a tractor according to claim 7, characterized in that: The output power in step S1 is greater than the output power in step S3, and the output power in step S3 is greater than the output power in step S4.

10. The control method of a tractor electric drive travel system according to claim 7, characterized in that In step S2, the vehicle speed is calculated by acquiring the rotation speed signal of the gear in the travel gearbox assembly (3).

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