CN104389998B - Variable-current reverse gear starting control method of multi-gear wire control automatic transmission - Google Patents

Abstract

The invention discloses a variable current reverse start control method of a multi-gear automatic transmission by wire. The method sets the vehicle speed value -v ₁ at the end of start and the minimum energization time T _δ required to eliminate the separation gap of the reverse electromagnetic clutch. Detect the switch signal of the R gear and the vehicle speed signal v of the vehicle speed sensor, and the electronic control unit shall respectively follow the current function I _a ( t ) = I ₁ ( 0 ≤ t ≤ T _δ ) of the reverse gear electromagnetic clutch in the first stage and reverse in the second stage. The energized current function of the gear electromagnetic clutch I _b ( v ) = αI ₁ + βI ₁ v / v ₁ ( 0 ≤ v ≤ v ₁ ) controls the energized current of the reverse gear electromagnetic clutch to realize the reverse gear start control of the automatic transmission by wire. The control method can meet the driving habits of different drivers, avoid the engine stalling during the starting process, and realize the stable starting of the automatic transmission by wire.

Description

Control method of variable current reverse gear starting for multi-gear-by-wire automatic transmission

technical field

The invention relates to a control method of an automatic transmission, more precisely, a control method for starting a reverse gear with variable current of a multi-speed wire-controlled automatic transmission.

Background technique

Automatic transmissions are widely used in various vehicles such as automobiles, electric vehicles, and construction machinery. The existing automatic transmissions mainly include hydromechanical automatic transmission (AT), metal belt continuously variable automatic transmission (CVT), mechanical automatic transmission (AMT) and dual clutch automatic transmission (DCT).

The above-mentioned four types of automatic transmissions all adopt electronically controlled hydraulic servo devices to realize the control of the shifting process, which has complex structure, high cost and increased control difficulty and complexity. In particular, the executive mechanism of DCT includes: oil supply mechanism composed of hydraulic pump, hydraulic valve and accumulator, shift actuator driven by hydraulic pressure or electric motor, clutch control mechanism driven by hydraulic pressure or electric motor. These hydraulic control mechanisms make the overall structure of the transmission complex, the cost is high, and the control difficulty and complexity are increased.

With the gradual maturity of automotive electronic technology and automatic control technology and the wide application of automotive network communication technology, automotive wire control technology has become the future development trend of automobiles; The controller replaces the mechanical and hydraulic systems, and the driver's manipulation action is converted into an electrical signal through the sensor, which is input to the electronic control unit, and the electronic control unit generates a control signal to drive the actuator to perform the required operation. Automobile control-by-wire technology can reduce the complexity of components, reduce hydraulic and mechanical transmission devices, and at the same time, the flexibility of wiring layout expands the free space of automobile design.

The high-speed gears of the forward gear and the internal meshing gear of the flywheel are constantly meshed, the high-speed gears of the reverse gear are constantly meshed with the central external meshing gear, and the electromagnetic clutch controls the separation and engagement of the high-speed gears of each gear and the driving gear. The driven gears of each gear on the intermediate shaft of the transmission output power through the planetary gear mechanism; the electromagnetic clutch of this multi-gear ring-arranged wire-controlled automatic transmission adopts wire-controlled power shifting, without slipping and power interruption.

In order to ensure the smooth start of the multi-speed automatic transmission by wire, avoid the engine flameout during the starting process, and adapt to the driving habits of different drivers such as quick start or slow acceleration start, it is necessary to control the starting process of the multi-speed automatic transmission by wire.

Contents of the invention

The object of the present invention is to provide a variable current reverse gear starting control method of a multi-speed wire-controlled automatic transmission that can not only consider the driver's intention and adapt to different driving habits, but also realize the smooth start of the vehicle. A variable current reverse gear start control method for a multi-speed wire-controlled automatic transmission. The control device of the multi-speed wire-controlled automatic transmission for realizing the control method includes an engine, a vehicle speed sensor, an R gear switch, an electronic control unit, and a reverse gear electromagnetic clutch.

Technical scheme of the present invention is as follows:

After the engine is started and ignited, the electronic control unit is powered on, and the variable current reverse gear starting control method of the multi-speed wire automatic transmission starts to run. The control method includes the following steps:

Step 1, the electric control unit detects the R gear switch signal and the vehicle speed signal v of the vehicle speed sensor;

Step 2. Determine whether the R gear is engaged: When the electronic control unit detects that the R gear switch signal is on, it is judged that the multi-gear automatic transmission is engaged in the R gear, and proceed to step 3; otherwise, when the electronic control unit detects the R gear When the gear switch signal is not connected, it is judged that the multi-gear automatic transmission by wire is not engaged in the R gear, and proceed to step 1;

Step 3. First-stage reverse electromagnetic clutch energization current control: The electronic control unit controls the reverse electromagnetic clutch according to the first-stage reverse electromagnetic clutch energization current function I _a ( t ) = I ₁ , ( 0 ≤ t ≤ T _δ ). The energizing current of the clutch, where: I ₁ is the rated value of the energizing current of the reverse gear electromagnetic clutch;

Step 4. Determine whether the duration of the control process t is greater than or equal to the minimum power-on time T _δ required to eliminate the separation gap of the reverse electromagnetic clutch: when the electronic control unit detects that the duration of the control process t is greater than or equal to the minimum required to eliminate the separation gap of the reverse electromagnetic clutch When the power-on time T _δ , go to step 5; otherwise, when the electronic control unit detects that the control process duration t is less than the minimum power-on time T _δ required to eliminate the separation gap of the reverse electromagnetic clutch, return to step 3;

Step 5. Second-stage reverse electromagnetic clutch energization current control: The electronic control unit is based on the second-stage reverse electromagnetic clutch energization current function I _b ( v ) = αI ₁ + βI ₁ v / v ₁ , ( 0 ≤ v ≤ v ₁ ), controlling the energized current of the reverse gear electromagnetic clutch, in the formula: I ₁ is the rated value of the energized current of the reverse gear electromagnetic clutch, α is the combination strength coefficient of the reverse gear electromagnetic clutch, and β is the relative increase current coefficient of the vehicle speed;

Step 6. Judging whether the vehicle speed signal v of the vehicle speed sensor is greater than or equal to the vehicle speed value v1 at the end _of start: when the electronic control unit detects that the vehicle speed signal v of the vehicle speed sensor is greater than or equal to the vehicle speed value v1 at the end _of start, the start control process ends; otherwise, when When the electronic control unit detects that the vehicle speed signal v of the vehicle speed sensor is less than the vehicle speed value v1 at the end _of starting, return to step 5.

In the variable current reverse start control method of the above-mentioned multi-gear automatic transmission by wire, the coupling strength coefficient α of the reverse electromagnetic clutch described in step 5 is a fixed value set, α =0.3～0.8; The vehicle speed-related increase current coefficient β is a fixed value set, β =0.2-0.6; the vehicle speed value v ₁ at the end of the start described in step 6 is a fixed value set, v ₁ =5-10km/h.

Compared with the prior art, the present invention has the advantages of:

(1) The variable current reverse gear starting control method of the multi-speed wire-controlled automatic transmission of the present invention can quickly eliminate the separation gap of the reverse gear electromagnetic clutch in the first stage of the reverse gear starting process, and gradually increase the reverse gear in the second stage. The energizing current of the gear electromagnetic clutch makes the transmission torque of the reverse gear electromagnetic clutch increase smoothly, avoids the engine stalling during the starting process, and realizes the smooth start of the vehicle;

(2) The variable current reverse gear starting control method of the multi-block wire-controlled automatic transmission of the present invention, the energized current function I _b ( v ) of the reverse gear electromagnetic clutch in the second stage of the reverse gear starting process is a function of the vehicle speed v , thus reverse The magnitude of the energizing current of the gear electromagnetic clutch changes with the change of the vehicle speed, and because the change of the vehicle speed is controlled by the driver, the control method can adapt to different drivers' starting acceleration habits.

Description of drawings

Fig. 1 is a schematic structural diagram of the control device and the transmission device for the first gear and reverse gear of the multi-gear-by-wire automatic transmission according to the embodiment of the present invention.

Fig. 2 is a structural schematic diagram of the control device and the transmission device of the first gear and the second gear of the multi-speed wire-controlled automatic transmission according to the embodiment of the present invention.

Fig. 3 is a structural schematic diagram of the control device and the transmission device for the third gear and the fourth gear of the multi-speed wire-controlled automatic transmission according to the embodiment of the present invention.

FIG. 4 is a flow chart of a control method for starting in reverse gear with variable current in the multi-gear-by-wire automatic transmission according to an embodiment of the present invention.

5 is a schematic diagram of the vehicle speed change process and the reverse electromagnetic clutch energized current change curve of the variable current reverse start control method of the multi-gear automatic transmission by wire according to the embodiment of the present invention.

In the figure: 1. Transmission input shaft 2. Housing 200. Engine 24. Transmission intermediate shaft 25. Transmission output shaft 3. Flywheel 3a. Power input end 3b. Power output end 31. Flywheel inner gear 32. Central outer gear 41. First gear electromagnetic clutch 411. First gear electromagnetic clutch slip ring 412. First gear electromagnetic clutch brush 42. Second gear electromagnetic clutch 421. Second gear electromagnetic clutch slip ring 422. Second gear electromagnetic clutch brush 43. Third gear electromagnetic clutch 431. Third gear electromagnetic clutch slip ring 432. Third gear electromagnetic clutch brush 44. Fourth gear electromagnetic clutch 441. Fourth gear electromagnetic clutch slip ring 442. Fourth gear electromagnetic clutch brush 4R. Reverse gear electromagnetic clutch 4R1. Reverse gear electromagnetic clutch Slip ring 4R2. Reverse gear electromagnetic clutch brush 4Z1. First gear main shaft 4Z2. Second gear main shaft 4Z3. Third gear main shaft 4Z4. Fourth gear main shaft 4ZR. Reverse gear main shaft 51. First gear high speed gear 52. Second gear high speed gear 53. Three High speed gear 54. Four high speed gear 5R. Reverse high speed gear 61. First gear driving gear 62. Second gear driving gear 63. Third gear driving gear 64. Fourth gear driving gear 6R. Reverse gear driving gear 71. First gear slave Driven gear 72. Second gear driven gear 73. Third gear driven gear 74. Fourth gear driven gear 7R. Reverse gear driven gear 91. Sun gear 92. Planetary gear 93. Ring gear 94. Planet carrier 100. Electric control Unit 100a, first gear control output terminal 100b, second gear control output terminal 100c, third gear control output terminal 100d, fourth gear control output terminal 100r, reverse gear control output terminal VSS, vehicle speed sensor R-SW, R gear switch.

detailed description

Below in conjunction with the drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention are described in detail. Obviously, the described embodiments are only part of the embodiments of the present invention, not all embodiments; based on the present invention Embodiments, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

A method for controlling start-up of a multi-speed by-wire automatic transmission with variable current and reverse gear. The control device for the multi-speed by-wire automatic transmission that realizes the control method includes an engine 200, a vehicle speed sensor VSS, an R gear switch R-SW, and an electronic control unit 100. , Reverse electromagnetic clutch 4R.

The housing 2 is fixedly installed with a first-gear electromagnetic clutch brush 412, a second-gear electromagnetic clutch brush 422, a third-gear electromagnetic clutch brush 432, a fourth-gear electromagnetic clutch brush 442, a reverse electromagnetic clutch brush 4R2, and a first-gear electromagnetic clutch brush. The electric brush 412, the second gear electromagnetic clutch brush 422, the third gear electromagnetic clutch brush 432, the fourth gear electromagnetic clutch brush 442, the reverse gear electromagnetic clutch brush 4R2 and the first gear electromagnetic clutch slip ring 411 and the second gear electromagnetic clutch slip ring respectively. Ring 421, third gear electromagnetic clutch slip ring 431, fourth gear electromagnetic clutch slip ring 441, reverse gear electromagnetic clutch slip ring 4R1 maintain sliding contact; first gear electromagnetic clutch brush 412 terminal, second gear electromagnetic clutch brush 422 wiring terminal, the connecting terminal of the third gear electromagnetic clutch brush 432, the connecting terminal of the fourth gear electromagnetic clutch brush 442, the connecting terminal of the reverse gear electromagnetic clutch brush 4R2 respectively through the first gear control output terminal 100a, The second gear control output terminal 100b, the third gear control output terminal 100c, the fourth gear control output terminal 100d, and the reverse gear control output terminal 100r are connected to each other.

The electronic control unit 100 controls the power-on or power-off of the first-gear electromagnetic clutch brush 412, the second-gear electromagnetic clutch brush 422, the third-gear electromagnetic clutch brush 432, the fourth-gear electromagnetic clutch brush 442, and the reverse gear electromagnetic clutch brush 4R2. , control the engagement and separation of the first gear electromagnetic clutch 41, the second gear electromagnetic clutch 42, the third gear electromagnetic clutch 43, the fourth gear electromagnetic clutch 44, and the reverse gear electromagnetic clutch 4R; the electronic control unit 100 controls the first gear electromagnetic clutch brush 412, The second gear electromagnetic clutch brush 422, the third gear electromagnetic clutch brush 432, the fourth gear electromagnetic clutch brush 442, the size of the energized voltage or current of the reverse gear electromagnetic clutch brush 4R2, control the first gear electromagnetic clutch 41, the second gear electromagnetic clutch 42. The engagement and separation speeds of the third gear electromagnetic clutch 43, the fourth gear electromagnetic clutch 44, and the reverse gear electromagnetic clutch 4R.

The transmission device realizing the multi-block automatic transmission by wire of the embodiment of the present invention comprises a transmission input shaft 1, a flywheel 3, a transmission intermediate shaft 24, a transmission output shaft 25, and a housing 2; one end of the flywheel 3 is a power input end 3a, and the power input The end 3a is connected to one end of the transmission input shaft 1; the other end of the flywheel 3 is the power output end 3b, and the power output end 3b is provided with a flywheel internal gear 31 and a central external gear 32; the flywheel internal gear 31 is located at the central external gear 32 outside; on the transmission intermediate shaft 24, the reverse gear driven gear 7R, the fourth gear driven gear 74, the third gear driven gear 73, the second gear driven gear 72, and the first gear driven gear 71 are fixedly connected in sequence. The end of the transmission intermediate shaft 24 away from the flywheel 3 is also fixedly connected with a sun gear 91 .

The flywheel internal meshing gear 31 is in constant mesh with the first speed high speed gear 51, the second speed high speed gear 52, the third speed high speed gear 53, and the fourth speed high speed gear 54 along its gear circumferential inner side; the central external meshing gear 32 and the reverse speed high speed gear 5R Always mesh.

The first gear high speed gear 51, the second gear high speed gear 52, the third gear high speed gear 53, and the fourth gear high speed gear 54 are respectively connected with the passive end of the first gear electromagnetic clutch 41, the passive end of the second gear electromagnetic clutch 42, and the passive end of the third gear electromagnetic clutch 43. terminal, the passive end of fourth gear electromagnetic clutch 44; Gear main shaft 4Z1, second gear main shaft 4Z2, third gear main shaft 4Z3, fourth gear main shaft 4Z4 are connected with first gear driving gear 61, second gear driving gear 62, third gear driving gear 63, fourth gear driving gear 64; first gear driving gear 61, The second gear driving gear 62, the third gear driving gear 63, and the fourth gear driving gear 64 are in constant mesh with the first gear driven gear 71, the second gear driven gear 72, the third gear driven gear 73, and the fourth gear driven gear 74 respectively.

The reverse gear high speed gear 5R is connected with the passive end of the reverse gear electromagnetic clutch 4R; the active end of the reverse gear electromagnetic clutch 4R is connected with the reverse gear driving gear 6R; the reverse gear driving gear 6R is connected with the reverse gear driven gear 7R through the reverse gear spindle 4ZR engage.

The sun gear 91 is constantly meshed with the planetary gear 92, and the planetary gear 92 is also constantly meshed with the ring gear 93. The planetary gear 92 is rolled and installed on the planet carrier 94 through its central bearing hole, and the planet carrier 94 is fixed on the transmission case 2. The ring gear 93 is connected to one end of the transmission output shaft 25 by a spline, and the other end of the transmission output shaft 25 is used as the power output end of the transmission.

The power transmission routes of each forward gear and reverse gear of the multi-gear-by-wire automatic transmission according to the embodiment of the present invention will be further described below with reference to FIG. 1 , FIG. 2 , and FIG. 3 .

First-speed transmission: the electronic control unit 100 controls the first-speed electromagnetic clutch 41 to be energized and engaged, and the other electromagnetic clutches are powered off and separated. The torque of the transmission input shaft 1 is transmitted to the first-speed high-speed gear 51 through the flywheel internal meshing gear 31, and then through the engaged first-speed gear. The electromagnetic clutch 41 transmits the power to the sun gear 91 through the meshing of the first gear driving gear 61 and the first gear driven gear 71, and finally outputs the power to the transmission output shaft 25 through the splines on the ring gear 93 to realize the first gear transmission.

Second-speed transmission: the electronic control unit 100 controls the second-speed electromagnetic clutch 42 to be energized and engaged, and the other electromagnetic clutches are de-energized and disengaged. The torque of the transmission input shaft 1 is transmitted to the second-speed high-speed gear 52 through the flywheel internal meshing gear 31, and then through the engaged second-speed gear. The electromagnetic clutch 42 transmits the power to the sun gear 91 through the engagement of the second gear driving gear 62 and the second gear driven gear 72, and finally outputs the power to the transmission output shaft 25 through the splines on the ring gear 93 to realize the second gear transmission.

Third-speed transmission: the electronic control unit 100 controls the third-speed electromagnetic clutch 43 to be energized and engaged, and the other electromagnetic clutches are de-energized and separated. The torque of the transmission input shaft 1 is transmitted to the third-speed high-speed gear 53 through the flywheel internal meshing gear 31, and then through the third-speed engaged gear. The electromagnetic clutch 43 transmits the power to the sun gear 91 through the engagement of the third gear driving gear 63 and the third gear driven gear 73, and finally outputs the power to the transmission output shaft 25 through the spline on the ring gear 93 to realize the third gear transmission.

Four-speed transmission: the electronic control unit 100 controls the fourth-speed electromagnetic clutch 44 to be energized and engaged, and the other electromagnetic clutches are de-energized and separated. The torque of the transmission input shaft 1 is transmitted to the fourth-speed high-speed gear 54 through the flywheel internal meshing gear 31, and then through the engaged fourth-speed gear. The electromagnetic clutch 44 transmits the power to the sun gear 91 through the engagement of the fourth gear driving gear 64 and the fourth gear driven gear 74, and finally outputs the power to the transmission output shaft 25 through the splines on the ring gear 93 to realize the fourth gear transmission.

Reverse gear transmission: the electronic control unit 100 controls the reverse gear electromagnetic clutch 4R to be energized and engaged, and the other electromagnetic clutches are powered off and separated. The torque of the transmission input shaft 1 is transmitted to the reverse gear high speed gear 5R through the central external meshing gear 32, and then through the engaged reverse gear The electromagnetic clutch 4R transmits the power to the sun gear 91 through the engagement of the reverse driving gear 6R and the reverse driven gear 7R, and finally outputs the power to the transmission output shaft 25 through the splines on the ring gear 93 to realize reverse gear transmission.

Neutral gear: the electronic control unit 100 controls the first gear electromagnetic clutch 41, the second gear electromagnetic clutch 42, the third gear electromagnetic clutch 43, the fourth gear electromagnetic clutch 44, and the reverse gear electromagnetic clutch 4R, all of which are in a power-off and separated state to realize neutral gear.

The flow chart of the variable current reverse gear starting control method of the multi-gear automatic transmission by wire of the present invention is shown in Figure 4. After the engine 200 is started and ignited, the electronic control unit 100 is powered on, and the variable current reverse gear of the multi-gear automatic transmission by wire starts. The control method begins to run, and the control method includes the following steps:

Step S1, the electronic control unit 100 detects the R gear switch R-SW signal and the vehicle speed signal v of the vehicle speed sensor VSS;

Step S2, judging whether the R gear is engaged: when the electronic control unit 100 detects that the R gear switch R-SW is turned on, it is judged that the multi-gear automatic transmission by wire is engaged in the R gear, and step S3 is performed; otherwise, when the electronic control unit 100 When it is detected that the R gear switch R-SW is not connected, it is judged that the multi-gear automatic transmission by wire is not engaged in the R gear, and step S1 is performed;

Step S3 , _first -stage reverse gear electromagnetic clutch 4R _energized current control: the electronic control unit ₁₀₀ controls The energizing current of reverse gear electromagnetic clutch 4R, in the formula: I ₁ is the rated value of the energizing current of reverse gear electromagnetic clutch 4R;

Step S4, judging whether the duration t of the control process is greater than or equal to the minimum power-on time T _δ required to eliminate the 4R separation gap of the reverse electromagnetic clutch: when the electronic control unit 100 detects that the duration t of the control process is greater than or equal to the elimination of the 4R separation gap of the reverse electromagnetic clutch When the required minimum energization time T _δ , proceed to step S5; otherwise, when the electronic control unit 100 detects that the control process duration t is less than the minimum energization time T _δ required to eliminate the separation gap of the reverse electromagnetic clutch 4R, return to step S3;

Step S5, second-stage reverse electromagnetic clutch 4R energized current control: the electronic control unit 100 according to the second-stage reverse electromagnetic clutch 4R energized current function I _b ( v ) = αI ₁ + βI ₁ v / v ₁ , ( 0 ≤ v ≤ v ₁ ), to control the energized current of the reverse electromagnetic clutch 4R, where: I ₁ is the rated value of the energized current of the reverse electromagnetic clutch 4R, α is the coupling strength coefficient of the reverse electromagnetic clutch 4R, and β is the vehicle speed correlation Increase the current coefficient;

Step S6, judging whether the vehicle speed signal v of the vehicle speed sensor VSS is greater than or equal to the start end vehicle speed value v1 : when the electronic control unit ₁₀₀ detects that the vehicle speed signal v _of the vehicle speed sensor VSS is greater than or equal to the start end end vehicle speed value v1 , the start control process ends; Otherwise, when the electronic control unit 100 detects that the vehicle speed signal v of the vehicle speed sensor VSS is smaller than the vehicle speed value v1 at the end _of starting, return to step S5.

In the present embodiment, the bonding strength coefficient α of the reverse electromagnetic clutch 4R is taken as 0.6; the vehicle speed-related increase current coefficient β is taken as 0.4; the required minimum power-on time T _δ for eliminating the separation gap of the reverse electromagnetic clutch 4R is taken as 250ms; The vehicle speed value v ₁ is taken as 7km/h.

Below in conjunction with Fig. 5, further illustrate the step S3 first stage reverse electromagnetic clutch 4R energized current control and step S5 second stage reverse electromagnetic clutch 4R energized current control process of the embodiment of the present invention:

As shown in Figure 5, the vehicle speed change process and the reverse electromagnetic clutch cycle power-on pulse width change curve of the variable current reverse gear start control method of the multi-gear automatic transmission by wire automatic transmission according to the embodiment of the present invention are shown. During the minimum energization time T _δ required for the separation gap of the gear electromagnetic clutch 4R, the electronic control unit 100 controls the energization current of the reverse gear electromagnetic clutch 4R according to the first stage reverse gear electromagnetic clutch 4R energized current function I _a ( t ) = I ₁ , This stage is used to eliminate the separation gap of the reverse electromagnetic clutch 4R; when the control process duration t is greater than or equal to the minimum power-on time Tδ required to eliminate the reverse electromagnetic clutch _4R separation gap, the electronic control unit 100 reverses according to the second stage. Electromagnetic clutch 4R energized current function I _b ( v ) = αI ₁ + βI ₁ v / v ₁ =0.6· I ₁ +0.4· I ₁ v /7(ms) to control the energized current of the reverse electromagnetic clutch 4R until the vehicle speed When the vehicle speed signal v _of the sensor VSS is greater than or equal to the start end vehicle speed value v1 , the start control process ends.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and can also be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art. Variations.

Claims (3)

1. A variable current reverse gear starting control method for a multi-block automatic transmission by wire, the multi-block automatic transmission by wire control device for realizing the reverse gear starting control method includes an engine (200), a vehicle speed sensor (VSS), and an R gear switch (R-SW), electronic control unit (100), reverse gear electromagnetic clutch (4R), it is characterized in that, described control method comprises the following steps: Step 1, the electronic control unit (100) detects the R gear switch (R-SW) signal and the vehicle speed signal v of the vehicle speed sensor (VSS); Step 2. Judging whether to engage R gear: When the electronic control unit (100) detects that the R gear switch (R-SW) signal is turned on, it is judged that the multi-gear automatic transmission by wire is engaged in R gear, and proceed to step 3; otherwise , when the electronic control unit (100) detects that the R gear switch (R-SW) signal is not connected, it is judged that the multi-gear-by-wire automatic transmission is not engaged in the R gear, and step 1 is performed; Step 3, first-stage reverse gear electromagnetic clutch (4R) energized current control: the electronic control unit (100) according to the first-stage reverse gear electromagnetic clutch (4R) energized current function I _a ( t ) = I ₁ , ( 0 ≤ t ≤ T _δ ), to control the energized current of the reverse electromagnetic clutch (4R), where: I ₁ is the rated value of the energized current of the reverse electromagnetic clutch (4R); Step 4. Determine whether the duration t of the control process is greater than or equal to the minimum energization time T _δ required to eliminate the separation gap of the reverse electromagnetic clutch (4R): when the electronic control unit (100) detects that the duration t of the control process is greater than or equal to the elimination of the reverse electromagnetic clutch When the minimum energization time T _δ required for the separation gap of the clutch (4R), proceed to step 5; otherwise, when the electronic control unit (100) detects that the duration t of the control process is less than the minimum energization required to eliminate the separation gap of the reverse electromagnetic clutch (4R) At time T _δ , return to step 3; Step 5. Second-stage reverse electromagnetic clutch (4R) energized current control: the electronic control unit (100) according to the second-stage reverse electromagnetic clutch (4R) energized current function I _b ( v ) = αI ₁ + βI ₁ v / v ₁ , ( 0 ≤ v ≤ v ₁ ), controls the energized current of the reverse electromagnetic clutch (4R), where: I ₁ is the rated value of the energized current of the reverse electromagnetic clutch (4R), α is the reverse electromagnetic clutch The bonding strength coefficient of (4R), β is the speed-related increase current coefficient; Step 6. Determine whether the vehicle speed signal v of the vehicle speed sensor (VSS) is greater than or equal to the vehicle speed value v1 at the end _of starting: when the electronic control unit (100) detects that the vehicle speed signal v of the vehicle speed sensor (VSS) is greater than or equal to the vehicle speed value v1 at the end _of starting , the start control process ends; otherwise, when the electronic control unit (100) detects that the vehicle speed signal v of the vehicle speed sensor (VSS) is less than the start end vehicle speed value v1 , return to step ₅ . 2. the variable current reverse gear start-up control method of multi-block wire-controlled automatic transmission as claimed in claim 1, is characterized in that, in described step 5 second stage reverse gear electromagnetic clutch (4R) energized current control, described The coupling strength coefficient α of the reverse electromagnetic clutch (4R) is a fixed value, α =0.3-0.8; the speed-related increase current coefficient β is a fixed value, β =0.2-0.6. 3. The variable current reverse gear starting control method of multi-block automatic transmission by wire as claimed in claim 1, characterized in that, in said step 6, it is judged whether the vehicle speed signal v of the vehicle speed sensor (VSS) is greater than or equal to the vehicle speed value at the end of starting In v ₁ , the vehicle speed value v ₁ at the end of starting is a set fixed value, v ₁ =5-10km/h.