CN104279317B - Variable-period downshift process control method of multi-gear wire-controlled automatic gearbox - Google Patents

Abstract

The invention discloses a variable-period downshift process control method of a multi-gear wire-controlled automatic gearbox. According to the method, whether the downshift from the second gear to the first gear, the downshift from the third gear to the second gear or the downshift from the fourth gear to the third gear is needed or not is judged by an electric control unit through detecting a D gear switching signal, a vehicle speed signal v of a vehicle speed sensor and an opening degree signal Alpha of an accelerator pedal position sensor, and the electrification current control of an electromagnetic clutch in each downshift process is carried out. The downshift process control method has the advantages that the input power interrupt of an engine in the downshift process can be avoided, in addition, the gear shifting impact can be avoided, and the stable downshift of the wire-controlled automatic gearbox is realized.

Description

Control method for variable-period downshift process of 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 a variable-period downshift process 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 shifting of the multi-speed automatic transmission by wire and avoid the interruption of the input power of the engine and the shock of shifting during the shifting process, it is necessary to control the shifting process of the multi-speed automatic transmission by wire.

Contents of the invention

The object of the present invention is to provide a control method for the variable-period downshifting process of a multi-gear-by-wire automatic transmission that can avoid interruption of engine input power and shifting impact during the shifting process, and can realize smooth downshifting of the vehicle. A control method for a variable-period downshift process of a multi-gear automatic transmission by wire, the control device of the multi-gear automatic transmission by wire for realizing the control method includes an engine, a D gear switch, a vehicle speed sensor, an accelerator pedal position sensor, an electronic control unit, First-speed electromagnetic clutch, second-speed electromagnetic clutch, third-speed electromagnetic clutch, and fourth-speed electromagnetic clutch, the law curve of second gear down first gear, third gear down second gear law, fourth gear down third gear law are stored in the electronic control unit in advance curve.

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 control method for the variable-period downshift process of the multi-gear-by-wire automatic transmission starts to run. The control method includes the following steps:

Step 1, the electronic control unit detects the D gear switch signal, the vehicle speed signal v of the vehicle speed sensor, and the opening signal α of the accelerator pedal position sensor;

Step 2. Determine whether to engage the D gear: when the electronic control unit detects that the D gear switch signal is on, go to step 3; otherwise, when the electronic control unit detects that the D gear switch signal is not on, go to step 1;

Step 3. Judging whether the second gear needs to be downshifted to the first gear: When the electronic control unit detects that the vehicle speed signal v of the vehicle speed sensor and the opening signal α of the accelerator pedal position sensor satisfy the second gear downshift in the downshift law curve of the multi-gear automatic transmission by wire When the downshift point on the regular curve of the first gear is judged that the second gear needs to be downshifted to the first gear, proceed to step 4; otherwise, when the electronic control unit detects that the vehicle speed signal v of the vehicle speed sensor and the opening signal α of the accelerator pedal position sensor are not When the downshift point on the second gear downshift regular curve in the downshift regular curve of the multi-gear automatic transmission by wire is satisfied, it is judged that downshifting from the second gear to the first gear is unnecessary, and proceed to step 6;

Step 4. The process control of downshifting from the second gear to the first gear: the electronic control unit detects the vehicle speed signal v of the vehicle speed sensor and the variable downshift control cycle function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } Determine the control period T ₂₁ for the second gear down to the first gear, and then determine the first gear Electromagnetic clutch current function I _1a ( t )={ I ₁ , 0 ≤ t ≤ T _1δ ; kI ₁ + I ₁ (1- k )( t - T _1δ )/( T ₂₁ - T _1δ ), T _1δ < t ≤ T ₂₁ }, control the energizing current of the electromagnetic clutch of the first gear, and at the same time determine the energizing current function of the electromagnetic clutch of the second gear I _2a ( t )={ I ₂ , 0 ≤ t ≤ lT _1δ ; 0 , lT _1δ < t ≤ T ₂₁ }, to control the energized current of the second gear electromagnetic clutch, where T _h is the maximum downshift control period; v ₁ is the vehicle speed corresponding to the maximum downshift control period; T _l is the minimum downshift control period; v ₂ is the minimum downshift control period Gear control period corresponds to the vehicle speed; I ₁ is the rated value of the energized current of the first gear electromagnetic clutch; I ₂ is the rated value of the _energized current of the second gear electromagnetic clutch; β is the change coefficient of the downshift control cycle; The minimum power-on time required for the clutch separation gap; k is the engagement strength coefficient; l is the delay separation time coefficient;

Step 5. Determine whether the duration t of the control process of downgrading from the second gear to the first gear is less than the control period T ₂₁ of the downgrade from the second gear to the first gear: when the duration t of the control process of downgrading from the second gear to the first gear is less than the control period T of the downgrade from the second gear to the first gear At ₂₁ o'clock, it is judged that the control process of downgrading from the second gear to the first gear has not ended, and return to step 4; otherwise, when the duration t of the control process of downgrading from the second gear to the first gear is greater than or equal to the control period T ₂₁ of the downgrading from the second gear to the first gear, judge The control process ends when the second gear is downgraded to the first gear, and returns to step 1;

Step 6. Judging whether the third gear needs to be downshifted to the second gear: When the electronic control unit detects that the vehicle speed signal v of the vehicle speed sensor and the opening signal α of the accelerator pedal position sensor satisfy the third gear downshift in the downshift law curve of the multi-gear automatic transmission by wire When the downshift point on the second-gear law curve is judged that the third gear needs to be downshifted to the second gear, proceed to step 7; otherwise, when the electronic control unit detects that the vehicle speed signal v of the vehicle speed sensor and the opening degree signal α of the accelerator pedal position sensor are not When satisfying the downshift point on the downshift law curve of the third gear and the second gear in the downshift law curve of the multi-gear automatic transmission by wire, it is judged that the downshift from the third gear to the second gear is unnecessary, and proceed to step 9;

Step 7. The third gear is downgraded to the second gear process control: the electronic control unit detects the vehicle speed signal v of the vehicle speed sensor and the downshift variable control period function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } Determine the control cycle T ₃₂ for the third gear down to the second gear, and then determine the second gear Electromagnetic clutch current function I _2b ( t )={ I ₂ , 0 ≤ t ≤ T _2δ ; kI ₂ + I ₂ (1- k )( t - T _2δ )/( T ₃₂ - T _2δ ), T _2δ < t ≤ T ₃₂ }, control the energized current of the second-gear electromagnetic clutch, and at the same time determine the energized current function of the third-gear electromagnetic clutch I _3b ( t )={ I ₃ , 0 ≤ t ≤ lT _2δ ; 0 , lT _2δ < t ≤ T ₃₂ }, to control the energized current of the third gear electromagnetic clutch, where T _h is the maximum downshift control period; v ₁ is the vehicle speed corresponding to the maximum downshift control period; T _l is the minimum downshift control period; v ₂ is the minimum downshift control period Gear control cycle corresponds to vehicle speed; I ₂ is the rated value of the energized current of the second gear electromagnetic clutch; I ₃ is the rated value of the _energized current of the third gear electromagnetic clutch; β is the change coefficient of the downshift control cycle; The minimum power-on time required for the clutch separation gap; k is the engagement strength coefficient; l is the delay separation time coefficient;

Step 8. Determine whether the duration t of the control process of downgrading from third gear to second gear is less than the control period _T32 of downgrading from third gear to second gear: when the duration t of the control process of downgrading from third gear to second gear is less than the control period T of downgrading from third gear to second gear At ₃₂ o'clock, it is judged that the control process of downgrading from third gear to second gear has not ended, and return to step 7; otherwise, when the duration t of the control process of downgrading from third gear to second gear is greater than or _equal to the control period T The control process ends when the third gear is downgraded to the second gear, and returns to step 1;

Step 9. Determine whether fourth gear needs to be downgraded to third gear: When the electronic control unit detects that the vehicle speed signal v of the vehicle speed sensor and the opening signal α of the accelerator pedal position sensor meet the requirements of the fourth gear in the downshift law curve of the multi-gear automatic transmission by wire 3rd gear law curve (D ₄ on the downshift point, it is judged that the 4th gear needs to be downgraded to the 3rd gear, and proceed to step 10; otherwise, when the electronic control unit detects the vehicle speed signal v of the vehicle speed sensor and the opening of the accelerator pedal position sensor Signal α does not satisfy the downshifting law curve of fourth gear and third gear in the downshifting regular curve of the multi-gear control automatic transmission by wire (when the downshifting point on D ₄ , it is judged that downshifting from fourth gear to third gear is unnecessary, and return to step 1;

Step 10, fourth gear down to third gear process control: the electronic control unit detects the vehicle speed signal v of the vehicle speed sensor and downshift variable control cycle function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } Determine the control period T ₄₃ for downshifting from the fourth gear to the third gear, and then determine the third gear Electromagnetic clutch current function I _3c ( t )={ I ₃ , 0 ≤ t ≤ T _3δ ; kI ₃ + I ₃ (1- k )( t - T _3δ )/( T ₄₃ - T _3δ ), T _3δ < t ≤ T ₄₃ }, control the energized current of the third-gear electromagnetic clutch, and at the same time determine the energized current function of the fourth-gear electromagnetic clutch I _4c ( t )={ I ₄ , 0 ≤ t ≤ lT _3δ ; 0 , lT _3δ < t ≤ T ₄₃ }, to control the energized current of the fourth gear electromagnetic clutch, where: T _h is the maximum downshift control period; v ₁ is the vehicle speed corresponding to the maximum downshift control period; T _l is the minimum downshift control period; v ₂ is the minimum downshift control period Gear control period corresponds to vehicle speed; I ₃ is the rated value of the energized current of the third gear electromagnetic clutch; I ₄ is the rated value of the _energized current of the fourth gear electromagnetic clutch; β is the change coefficient of the downshift control cycle; The minimum power-on time required for the clutch separation gap; k is the engagement strength coefficient; l is the delay separation time coefficient;

Step 11. Determine whether the duration t of the control process of downgrading from fourth gear to third gear is less than the control period _T43 of downgrading from fourth gear to third gear: when the duration t of the control process of downgrading from fourth gear to third gear is less than the control period T of downgrading from fourth gear to third gear At ₄₃ , it is judged that the control process of downgrading from fourth gear to third gear has not ended, and return to step 10; otherwise, when the duration t of the control process of downgrading from fourth gear to third gear is greater than or equal to the control period T43 of _downgrading from fourth gear to third gear, it is judged that Downgrade to third gear from the fourth gear and the control process ends, and return to step 1.

After the driver turns off the ignition switch, the electric control unit is powered off, and the control method for the variable-period downshift process of the multi-gear automatic transmission by wire ends its operation.

In the process control of step 4 downshifting from second gear to first gear, step 7 downshifting from third gear down to second gear, and step 10 downshifting from fourth gear down to third gear process control, the downshift control period variation coefficient β is a fixed value set , β= 0.7~1.3; joint strength coefficient k is a fixed value set, k =0.5~0.8; delay separation time coefficient l is a fixed value set, l= 0.8~1.2.

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

(1) In the control method of the variable-period downshifting process of the multi-gear-by-wire automatic transmission of the present invention, the downshifting control period decreases with the increase of vehicle speed, so that the time control of the downshifting process is more accurate, and the requirements for downshifting of different vehicle speeds are satisfied. control cycle requirements;

(2) The variable-period downshift process control method of the multi-gear-by-wire automatic transmission of the present invention can quickly eliminate the separation gap of the electromagnetic clutch of the low gear during the downshift process, and gradually increase the energizing current of the electromagnetic clutch of the low gear , to realize the smooth increase of the transmission torque of the electromagnetic clutch in the low gear, thereby avoiding the shifting shock phenomenon during the downshifting process;

(3) The control method of the variable-period downshifting process of the multi-gear-by-wire automatic transmission of the present invention can control the high-gear electromagnetic clutch to ensure reliable engagement before the low-gear electromagnetic clutch transmits torque during the downshift process, The power transmission is maintained, and after the electromagnetic clutch of the low gear starts to transmit power, the electromagnetic clutch of the high gear disengages quickly, thereby avoiding the power interruption phenomenon during the downshifting process.

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 a variable-period downshift process of a multi-gear-by-wire automatic transmission according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of a downshift regularity curve of a multi-speed by-wire automatic transmission according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of a variable cycle control curve of a multi-speed by-wire automatic transmission according to an embodiment of the present invention.

Fig. 7 is the current function I _1a ( t ) curve of the electromagnetic clutch of the first gear and the current function I _2a ( t ) of the electromagnetic clutch of the second gear in the process control of the multi-speed wire control automatic transmission according to the embodiment of the present invention. schematic diagram.

Fig. 8 is the current function I _2b ( t ) curve of the second gear electromagnetic clutch and the current function I _3b ( t ) curve of the third gear electromagnetic clutch in the process control of the multi-speed wire control automatic transmission according to the embodiment of the present invention. schematic diagram.

Fig. 9 is the current function I _3c ( t ) curve of the electromagnetic clutch of the third gear and the current function I _4c ( t ) of the electromagnetic clutch of the fourth gear in the process control of the second gear down to the first gear of the multi-gear automatic transmission by wire according to the embodiment of the present invention schematic diagram.

In the figure: 1. Transmission input shaft 2. Transmission housing 200. Engine 24. Transmission intermediate shaft 25. Transmission output shaft 3. Flywheel 3a. Power input end 3b. Power output end 31. Flywheel inner meshing gear 32. Central outer meshing Gear 33. Intermediate 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. Third-speed high-speed gear 54. Fourth-speed high-speed gear 5R. Reverse high-speed gear 61. First-speed driving gear 62. Second-speed driving gear 63. Third-speed driving gear 64. Fourth-speed driving gear 6R. Reverse gear driving gear 71. First gear 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 Frame 100. Electronic 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 D-SW.D Gear switch APS. Accelerator pedal position sensor D ₂₁ . Second gear down first gear regular curve D ₃₂ . Third gear down second gear regular curve D ₄₃ . Fourth gear down third gear regular curve.

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 a variable-period downshift process of a multi-gear automatic transmission by wire. The control device for realizing the multi-speed automatic transmission by wire according to the embodiment of the present invention includes an engine 200, a D gear switch D-SW, a vehicle speed sensor VSS, and an accelerator pedal position Sensor APS, electronic control unit 100, first-gear electromagnetic clutch 41, second-gear electromagnetic clutch 42, third-gear electromagnetic clutch 43, fourth-gear electromagnetic clutch 44, in the electronic control unit 100, the regular curve D ₂₁ for downshifting of second gear and first gear is stored in advance , the regular curve D ₃₂ of the second gear down from the third gear, and the regular curve D ₄₃ of the third gear down from the fourth gear.

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 .

Flywheel internal meshing gear 31 is in constant mesh with first-speed high-speed gear 51, second-speed high-speed gear 52, third-speed high-speed gear 53, and fourth-speed high-speed gear 54 along its gear circumferential inner side; each forward high-speed gear and the empty sleeve are in the middle of the transmission The intermediate gear 33 on the shaft 24 is in constant mesh; the central external gear 32 is in constant mesh with the reverse high speed gear 5R.

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 control method for the variable-cycle downshift process of the multi-block 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-cycle downshift process of the multi-block automatic transmission by wire is performed. The control method begins to run, and the control method includes the following steps:

Step S1, the electronic control unit 100 detects the D gear switch D-SW signal, the vehicle speed signal v of the vehicle speed sensor VSS, and the opening signal α of the accelerator pedal position sensor APS;

Step S2, judging whether to engage the D gear: when the electronic control unit 100 detects that the D gear switch D-SW signal is on, proceed to step S3; otherwise, when the electronic control unit 100 detects that the D gear switch D-SW signal is not connected When it is passed, proceed to step S1;

Step S3, judging whether the second gear needs to be downgraded to the first gear: as shown in Fig. 5, when the electronic control unit 100 detects that the vehicle speed signal v of the vehicle speed sensor VSS and the opening signal α of the accelerator pedal position sensor APS meet the requirements of multi-gear automatic control by wire When the downshift point on the second gear and first gear down regular curve _D21 in the downshift regular curve of the transmission, it is judged that the second gear needs to be downgraded to the first gear, and step S4 is performed; otherwise, when the electronic control unit 100 detects the vehicle speed of the vehicle speed sensor VSS When the signal v and the opening degree signal α of the accelerator pedal position sensor APS do not meet the downshift point on the second gear down and first gear down regular curve D ₂₁ in the downshift regular curve of the multi-gear automatic transmission by wire, it is judged that the downshift to the second gear is unnecessary. First gear, go to step S6;

Step S4, second gear down to first gear process control: as shown in Figure 6, the electronic control unit 100 controls the cycle function T ( v ) ={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } Determine the second gear down to the first gear Control cycle T ₂₁ , and then determine the energized current function I _1a ( t )={ I ₁ , 0 ≤ t ≤ T _1δ ; kI ₁ + I ₁ (1- k )( t - T _1δ )/( T ₂₁ - T _1δ ), T _1δ < t ≤ T ₂₁ }, control the energizing current of the first gear electromagnetic clutch 41, and at the same time determine the energizing current function I _2a ( t ) of the second gear electromagnetic clutch 42 = { I ₂ , 0 ≤ t ≤ lT _1δ ; 0 , lT _1δ < t ≤ T ₂₁ }, to control the energized current of the second gear electromagnetic clutch 42, where: T _h is the maximum downshift control period; v ₁ is the vehicle speed corresponding to the maximum downshift control period; T _l is the minimum downshift control cycle; v ₂ is the vehicle speed corresponding to the minimum downshift control cycle; I ₁ is the rated value of the energized current of the first gear electromagnetic clutch 41; I ₂ is the rated value of the energized current of the second gear electromagnetic clutch 42; β is Downshift control cycle variation coefficient; T _1δ is the minimum power-on time required for eliminating the separation gap of the first gear electromagnetic clutch 41; k is the engagement strength coefficient; l is the delay separation time coefficient;

Step S5, determine whether the duration t of the control process of downgrading from the second gear to the first gear is less than the control period T ₂₁ of the downgrading from the second gear to the first gear: when the duration t of the control process of downgrading from the second gear to the first gear is less than the control period T of the downgrading from the second gear to the first gear At ₂₁ o'clock, it is judged that the control process of downgrading from second gear to first gear has not ended, and return to step S4; otherwise, when the duration t of the control process of downgrading from second gear to first gear is greater than or equal to the control period T ₂₁ of downgrading from second gear to first gear, it is judged that The control process ends when the second gear is downgraded to the first gear, and returns to step S1;

Step S6, judging whether the third gear needs to be downshifted to the second gear: when the electronic control unit 100 detects that the vehicle speed signal v of the vehicle speed sensor VSS and the opening degree signal α of the accelerator pedal position sensor APS satisfy the downshifting rule curve of the multi-gear automatic transmission by wire When the downshift point on the third-gear and second-gear rule curve _D32 is determined, it is judged that the third gear needs to be downgraded to the second gear, and step S7 is performed; otherwise, when the electronic control unit 100 detects the vehicle speed signal v of the vehicle speed sensor VSS and the position of the accelerator pedal When the opening degree signal α of the sensor APS does not satisfy the downshift point on the third gear down second gear regular curve _D32 in the downshift regular curve of the multi-gear automatic transmission by wire, it is judged that the third gear is not required to be downshifted to the second gear, and step S9 is performed. ;

Step S7, third gear down to second gear process control: the electronic control unit 100 uses the detected vehicle speed signal v of the vehicle speed sensor VSS and downshift variable control cycle function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } Determine the control period T ₃₂ for downshifting from the third gear to the second gear, and then Determine the energized current function of the second gear electromagnetic clutch 42 I _2b ( t )={ I ₂ , 0 ≤ t ≤ T _2δ ; kI ₂ + I ₂ (1- k )( t - T _2δ )/( T ₃₂ - T _2δ ) , T _2δ < t ≤ T ₃₂ }, control the energizing current of the second-gear electromagnetic clutch 42, and simultaneously determine the energizing current function I _3b ( t ) of the third-gear electromagnetic clutch 43 ={ I ₃ , 0 ≤ t ≤ lT _2δ ; 0 , lT _2δ < t ≤ T ₃₂ }, to control the energized current of the third-gear electromagnetic clutch 43, where: T _h is the maximum downshift control period; v ₁ is the vehicle speed corresponding to the maximum downshift control period; T _l is the minimum downshift control period ; V ₂ is the corresponding vehicle speed of the minimum downshift control cycle; I ₂ is the rated value of the energized current of the second gear electromagnetic clutch 42; I ₃ is the rated value of the energized current of the third gear electromagnetic clutch 43; β is the downshift control cycle variation coefficient ; T _2δ is the minimum energization time required to eliminate the separation gap of the second gear electromagnetic clutch 42; k is the engagement strength coefficient; l is the delay separation time coefficient;

Step S8, determine whether the duration t of the control process of downgrading from third gear to second gear is less than the control period _T32 of downgrading from third gear to second gear: when the duration t of the control process of downgrading from third gear to second gear is less than the control period T of downgrading to second gear from third gear At _{32 o'clock} , it is judged that the control process of downgrading from third gear to second gear has not ended, and return to step S7; The control process ends when the third gear is downgraded to the second gear, and returns to step S1;

Step S9, judging whether the fourth gear needs to be downshifted to the third gear: when the electronic control unit 100 detects that the vehicle speed signal v of the vehicle speed sensor VSS and the opening degree signal α of the accelerator pedal position sensor APS satisfy the downshift rule curve of the multi-gear automatic transmission by wire When the downshift point on the fourth gear down to third gear regular curve _D43 , it is judged that the fourth gear needs to be downgraded to the third gear, and proceed to step S10; otherwise, when the electronic control unit 100 detects the vehicle speed signal v of the vehicle speed sensor VSS and the position of the accelerator pedal When the opening degree signal α of the sensor APS does not satisfy the downshift point on the downshift regular curve D ₄₃ of the fourth gear and third gear in the multi-gear automatic transmission by wire downshift regular curve, it is judged that the downshift from the fourth gear to the third gear is unnecessary, and return to the step S1;

Step S10, downshifting from the fourth gear to the third gear process control: the electronic control unit 100 uses the detected vehicle speed signal v from the vehicle speed sensor VSS and downshift variable control cycle function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } Determine the control period T ₄₃ for downshifting from the fourth gear to the third gear, and then Determine the energized current function of the third gear electromagnetic clutch 43 I _3c ( t )={ I ₃ , 0 ≤ t ≤ T _3δ ; kI ₃ + I ₃ (1- k )( t - T _3δ )/( T ₄₃ - T _3δ ) , T _3δ < t ≤ T ₄₃ }, control the energized current of the third-speed electromagnetic clutch 43, and at the same time determine the energized current function I _4c ( t ) of the fourth-speed electromagnetic clutch 44={ I ₄ , 0 ≤ t ≤ lT _3δ ; 0 , lT _3δ < t ≤ T ₄₃ }, controls the energized current of the fourth gear electromagnetic clutch 44, where: T _h is the maximum downshift control period; v ₁ is the vehicle speed corresponding to the maximum downshift control period; T _l is the minimum downshift control period ; v ₂ is the corresponding vehicle speed of the minimum downshift control cycle; I ₃ is the rated value of the energized current of the third gear electromagnetic clutch 43; I ₄ is the rated value of the energized current of the fourth gear electromagnetic clutch 44; β is the downshift control cycle variation coefficient ; T _3δ is the minimum energization time required to eliminate the separation gap of the third gear electromagnetic clutch 43; k is the engagement strength coefficient; l is the delay separation time coefficient;

Step S11, determine whether the duration t of the control process of downgrading from fourth gear to third gear is less than the control period _T43 of downgrading from fourth gear to third gear: when the duration t of the control process of downgrading from fourth gear to third gear is less than the control period T of downgrading from fourth gear to third gear At ₄₃ , it is judged that the control process of downgrading from _fourth gear to third gear has not ended, and return to step S10; The control process for downgrading from the fourth gear to the third gear ends, and returns to step S1.

After the driver turns off the ignition switch, the electronic control unit 100 is powered off, and the control method of the multi-gear automatic transmission by wire is finished running.

In this embodiment, the downshift control cycle variation coefficient β is taken as 1; the engagement strength coefficient k is taken as 0.6; the delay separation time coefficient l is taken as _1.0 ; Eliminate the required minimum energization time T _2δ of the separation gap of the second gear electromagnetic clutch 42 and the minimum _energization time T 3 _δ required for eliminating the separation gap of the third gear electromagnetic clutch 43 are all taken as 250ms ; _The downshift control period T1 is taken as 400ms; the minimum downshift control period corresponding to the vehicle speed v2 is taken as 50km/h _; the maximum downshift control period corresponding to the vehicle speed v1 is taken as _15km /h.

Below in conjunction with Fig. 5, Fig. 6, Fig. 7, step S3 of the embodiment of the present invention is further described to determine whether the second gear is downgraded to the first gear and step S4 the second gear is downgraded to the first gear process control:

As shown in Figure 5, the schematic diagram of the downshifting regularity curve of the multi-block automatic transmission by wire in the embodiment of the present invention, D ₂₁ is the downshifting regularity curve of the second gear, D ₃₂ is the downshifting regular curve of the third gear, and D ₄₃ is the downshifting regularity curve of the fourth gear The regular curve of the third gear; when the vehicle speed signal v and the accelerator pedal opening signal α run to the point A(12,50), the electronic control unit 100 judges that the point A is the second gear and the first downshift according to the downshift regular curve of the multi-gear automatic transmission by wire. The downshift point on the regular curve D ₂₁ of the gear, and then carry out the second gear down to the first gear process control;

As shown in Fig. 6 , the schematic diagram of the variable period control law curve of the multi-speed wire automatic transmission according to the embodiment of the present invention, the downshift control period is according to the downshift variable control period function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } determined; the downshift point A in Figure 5 ( 12,50), the vehicle speed signal v =12km/h, the corresponding downshift control cycle T (12)={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ }=800ms, which is the point Aˊ(12,800) in Figure 6;

As shown in Fig. 7, a schematic diagram of the law curve of the current function I _1a ( t ) of the first gear electromagnetic clutch and the law curve of the current function I _2a ( t ) of the second gear electromagnetic clutch of the multi-speed wire-controlled automatic transmission of the embodiment of the present invention, the first gear Electromagnetic clutch 41 energized current function I _1a ( t )={ I ₁ , 0 ≤ t ≤250ms; 0.6· I ₁ +0.4· I ₁ ·( t -250)/( T ₂₁ -250),250ms< t ≤ T ₂₁ }, second gear electromagnetic clutch 42 energized current function I _2a ( t )={ I ₂ , 0 ≤ t ≤ 250ms; 0 , 250ms< t ≤ T ₂₁ }.

Below in conjunction with Fig. 5, Fig. 6, Fig. 8, step S6 of the embodiment of the present invention is further described to determine whether the third gear is downgraded to the second gear and step S7, the third gear is downgraded to the second gear process control:

As shown in Fig. 5, the schematic diagram of the downshift regularity curve of the multi-gear automatic transmission by wire according to the embodiment of the present invention, when the vehicle speed signal v and the accelerator pedal opening signal α run to point B(36,50), the electronic control unit 100 The shift-by-wire automatic transmission downshift law curve determines that point B is the downshift point on the third gear down second gear law curve D ₃₂ , and then the third gear is downgraded to the second gear process control;

As shown in Figure 6, the schematic diagram of the variable period control curve of the multi-speed wire automatic transmission according to the embodiment of the present invention, the downshift control period is according to the downshift variable control period function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } is determined; ,50), vehicle speed signal v =36km/h, corresponding downshift control period T (36)={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ }=400+1×400×(50-36)/(50-15)=560ms, which is Bˊ(36,560 )point;

As shown in Figure 8, the second-gear electromagnetic clutch energized current function I _2b ( t ) curve and the third-gear electromagnetic clutch energized current function I _3b ( t ) curve schematic diagram of the multi-gear-by-wire automatic transmission of the embodiment of the present invention, the second-gear electromagnetic clutch 42 Current function I _2b ( t )={ I ₂ , 0 ≤ t ≤250ms; 0.6· I ₂ +0.4· I ₂ ·( t -250)/( T ₃₂ -250), 250ms< t ≤ T ₃₂ } , the energized current function of the third-gear electromagnetic clutch 43 I _3b ( t )={ I ₃ , 0 ≤ t ≤ 250ms; 0 , 250ms< t ≤ T ₃₂ }.

Below in conjunction with Fig. 5, Fig. 6, Fig. 9, step S9 of the embodiment of the present invention is further described to determine whether to step down from the fourth gear to the third gear and step S10 to step down from the fourth gear to the third gear process control process:

As shown in Fig. 5 , the schematic diagram of the downshift regularity curve of the multi-gear automatic transmission by wire according to the embodiment of the present invention, when the vehicle speed signal v and the accelerator pedal opening signal α run to point C(59,50), the electronic control unit 100 The shift-by-wire automatic transmission downshift law curve determines that point C is the downshift point on the fourth gear down third gear law curve D ₄₃ , and then the downshifting to third gear process control is performed;

As shown in Figure 6, the schematic diagram of the variable period control curve of the multi-speed wire automatic transmission according to the embodiment of the present invention, the downshift control period is according to the downshift variable control period function T ( v )={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ } is determined; as shown in Figure 5, the downshift point C(59 ,50), vehicle speed signal v =59km/h, corresponding downshift control period T (59)={ T _h , 0 ≤ v < v ₁ ; T _l + βT _l ( v ₂ - v )/( v ₂ - v ₁ ), v ₁ ≤ v ≤ v ₂ ; T _l , v > v ₂ }=400ms, which is the point Cˊ(59,400) in Figure 6.

As shown in Figure 9, the third-gear electromagnetic clutch energized current function I _3c ( t ) curve and the fourth-gear electromagnetic clutch energized current function I _4c ( t ) curve schematic diagram of the multi-gear-by-wire automatic transmission of the embodiment of the present invention, the third-gear electromagnetic clutch 43 Current function I _3c ( t )={ I ₃ , 0 ≤ t ≤250ms; 0.6· I ₃ +0.4· I ₃ ·( t -250)/( T ₄₃ -250), 250ms< t ≤ T ₄₃ } , the energized current function of the fourth-speed electromagnetic clutch 44 I _4c ( t )={ I ₄ , 0 ≤ t ≤ 250ms; 0 , 250ms< t ≤ T ₄₃ }.

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 (2)

1. a kind of variable period downshift course control method for use keeping off line traffic control automatic transmission, realizes many gears line traffic control of this control method more The control device of automatic transmission includes electromotor (200), D position switch (D-SW), vehicle speed sensor (VSS), accelerator pedal position Put sensor (APS), ECU (100), one gear electromagnetic clutch (41), two gear electromagnetic clutch (42), three gear electromagnetism from Clutch (43), four gears electromagnetic clutch (44), have been previously stored two gear fall one gear law curve in ECU (100) (D₂₁), three gear fall two gear law curve (D₃₂), four gear fall three gear law curve (D₄₃) it is characterised in that described control method bag Include following steps：

Step 1, ECU (100) detection D position switch (D-SW) signal, the GES of vehicle speed sensor (VSS)v, accelerate The opening amount signal of pedal position sensor (APS)α；

Step 2, judge whether to be linked into D gear：When ECU (100) detects D position switch (D-SW) signal and connects, walked Rapid 3；Otherwise, when ECU (100) detects D position switch (D-SW) signal access failure, carry out step 1；

Step 3, judge whether to need two gears to be down to a gear：When ECU (100) detects the speed of vehicle speed sensor (VSS) SignalvOpening amount signal with accelerator pedal position sensor (APS)αMeet keep off in line traffic control automatic transmission downshift law curve more Two gear fall one gear law curve (D₂₁) on downshift point when, be judged as needing two gears to be down to a gear, carry out step 4；Otherwise, work as electricity Control unit (100) detects the GES of vehicle speed sensor (VSS)vAperture letter with accelerator pedal position sensor (APS) NumberαIt is unsatisfactory for keeping off two gear fall one gear law curve (D in line traffic control automatic transmission downshift law curve more₂₁) on downshift point when, It is judged as not needing two gears to be down to a gear, carry out step 6；

Step 4, two gears are down to a gear process control：The speed of the vehicle speed sensor (VSS) by detecting for the ECU (100) SignalvWith downshift variable controlling cycle functionT(v)={T _h ,0≤v<v ₁ ;T _l +βT _l (v ₂ -v)/(v ₂ -v ₁ ),v ₁ ≤v≤v ₂ ; T _l ,v>v ₂ Determine that two gears are down to a gear controlling cycleT ₂₁ , and then determine gear electromagnetic clutch (41) electrical current functionI _1a (t)={I ₁ ,0≤t≤T _1δ ;kI ₁ +I ₁ (1-k)(t-T _1δ )/(T ₂₁ -T _1δ ),T _1δ <t≤T ₂₁ , control a gear electromagnetic clutch (41) electrical current, and determine two gear electromagnetic clutch (42) electrical current functions simultaneouslyI _2a (t)={I ₂ ,0≤t≤lT _1δ ; 0,lT _1δ <t≤T ₂₁ , control the electrical current of two gears electromagnetic clutch (42), in formula：T_hFor maximum downshift controlling cycle；v ₁ For Maximum downshift controlling cycle corresponds to speed；T _l For minimum downshift controlling cycle；v ₂ Correspond to speed for minimum downshift controlling cycle；I ₁ Rated value for the electrical current of gear electromagnetic clutch (41)；I ₂ Specified for two electrical currents keeping off electromagnetic clutch (42) Value；βFor downshift controlling cycle variation coefficient；T _1δ For eliminating the minimum energising required for gear electromagnetic clutch (41) Separation Time；kFor bond strength coefficient；lFor postponing disengaging time coefficient；

Step 5, judge two gear be down to a gear control process persistent periodtWhether it is down to a gear controlling cycle less than two gearsT ₂₁ ：When Two gears are down to a gear control process persistent periodtIt is down to a gear controlling cycle less than two gearsT ₂₁ When, it is judged as that two gears are down to a gear Control process not yet terminates, and returns to step 4；Otherwise, when two gears are down to a gear control process persistent periodtMore than or equal to two gears It is down to a gear controlling cycleT ₂₁ When, it is judged as that two gears are down to a gear control process and are terminated, return to step 1；

Step 6, judge whether to need three gears to be down to two gears：When ECU (100) detects the speed of vehicle speed sensor (VSS) SignalvOpening amount signal with accelerator pedal position sensor (APS)αMeet keep off in line traffic control automatic transmission downshift law curve more Three gear fall two gear law curve (D₃₂) on downshift point when, be judged as needing three gears to be down to two gears, carry out step 7；Otherwise, work as electricity Control unit (100) detects the GES of vehicle speed sensor (VSS)vAperture letter with accelerator pedal position sensor (APS) NumberαIt is unsatisfactory for keeping off three gear fall two gear law curve (D in line traffic control automatic transmission downshift law curve more₃₂) on downshift point when, It is judged as not needing three gears to be down to two gears, carry out step 9；

Step 7, three gears are down to two gear process control：The speed of the vehicle speed sensor (VSS) by detecting for the ECU (100) SignalvWith downshift variable controlling cycle functionT(v)={T _h ,0≤v<v ₁ ;T _l +βT _l (v ₂ -v)/(v ₂ -v ₁ ),v ₁ ≤v≤v ₂ ; T _l ,v>v ₂ Determine that three gears are down to two gear controlling cyclesT ₃₂ , and then determine two gear electromagnetic clutch (42) electrical current functionsI _2b (t)={I ₂ ,0≤t≤T _2δ ;kI ₂ +I ₂ (1-k)(t-T _2δ )/(T ₃₂ -T _2δ ),T _2δ <t≤T ₃₂ , control two gear electromagnetic clutchs (42) electrical current, and determine three gear electromagnetic clutch (43) electrical current functions simultaneouslyI _3b (t)={I ₃ ,0≤t≤lT _2δ ; 0,lT _2δ <t≤T ₃₂ , control the electrical current of three gears electromagnetic clutch (43), in formula：T_hFor maximum downshift controlling cycle；v ₁ For Maximum downshift controlling cycle corresponds to speed；T _l For minimum downshift controlling cycle；v ₂ Correspond to speed for minimum downshift controlling cycle；I ₂ Rated value for the electrical current of two gears electromagnetic clutch (42)；I ₃ Specified for three electrical currents keeping off electromagnetic clutch (43) Value；βFor downshift controlling cycle variation coefficient；T _2δ For eliminating the minimum energising required for two gear electromagnetic clutch (42) Separations Time；kFor bond strength coefficient；lFor postponing disengaging time coefficient；

Step 8, judge three gear be down to for two gear control process persistent periodtWhether it is down to two gear controlling cycles less than three gearsT ₃₂ ：When Three gears were down to for two gear control process persistent periodtIt is down to two gear controlling cycles less than three gearsT ₃₂ When, it is judged as that three gears are down to two gears Control process not yet terminates, and returns to step 7；Otherwise, when three gears were down to for two gear control process persistent periodtMore than or equal to three gears It is down to two gear controlling cyclesT ₃₂ When, it is judged as that three gears are down to two gear control process and are terminated, return to step 1；

Step 9, judge whether to need four gears to be down to three gears：When ECU (100) detects the speed of vehicle speed sensor (VSS) SignalvOpening amount signal with accelerator pedal position sensor (APS)αMeet keep off in line traffic control automatic transmission downshift law curve more Four gear fall three gear law curve (D₄₃) on downshift point when, be judged as needing four gears to be down to three gears, carry out step 10；Otherwise, when ECU (100) detects the GES of vehicle speed sensor (VSS)vAperture with accelerator pedal position sensor (APS) SignalαIt is unsatisfactory for keeping off four gear fall three gear law curve (D in line traffic control automatic transmission downshift law curve more₄₃) on downshift point When, it is judged as not needing four gears to be down to three gears, return to step 1；

Step 10, four gears are down to three gear process control：The car of the vehicle speed sensor (VSS) by detecting for the ECU (100) Fast signalvWith downshift variable controlling cycle functionT(v)={T _h ,0≤v<v ₁ ;T _l +βT _l (v ₂ -v)/(v ₂ -v ₁ ),v ₁ ≤v≤v ₂ ; T _l ,v>v ₂ Determine that four gears are down to three gear controlling cyclesT ₄₃ , and then determine three gear electromagnetic clutch (43) electrical current functionsI _3c (t)={I ₃ ,0≤t≤T _3δ ;kI ₃ +I ₃ (1-k)(t-T _3δ )/(T ₄₃ -T _3δ ),T _3δ <t≤T ₄₃ , control three gear electromagnetic clutchs (43) electrical current, and determine four gear electromagnetic clutch (44) electrical current functions simultaneouslyI _4c (t)={I ₄ ,0≤t≤lT _3δ ; 0,lT _3δ <t≤T ₄₃ , control the electrical current of four gears electromagnetic clutch (44), in formula：T_hFor maximum downshift controlling cycle；v ₁ For Maximum downshift controlling cycle corresponds to speed；T _l For minimum downshift controlling cycle；v ₂ Correspond to speed for minimum downshift controlling cycle；I ₃ Rated value for the electrical current of three gears electromagnetic clutch (43)；I ₄ Specified for four electrical currents keeping off electromagnetic clutch (44) Value；βFor downshift controlling cycle variation coefficient；T _3δ For eliminating the minimum energising required for three gear electromagnetic clutch (43) Separations Time；kFor bond strength coefficient；lFor postponing disengaging time coefficient；

Step 11, judge four gear be down to for three gear control process persistent periodtWhether it is down to three gear controlling cycles less than four gearsT ₄₃ ：When Four gears were down to for three gear control process persistent periodtIt is down to three gear controlling cycles less than four gearsT ₄₃ When, it is judged as that four gears are down to three gears Control process not yet terminates, and returns to step 10；Otherwise, when four gears were down to for three gear control process persistent periodtMore than or equal to four Gear is down to three gear controlling cyclesT ₄₃ When, it is judged as that four gears are down to three gear control process and are terminated, return to step 1.

2. as claimed in claim 1 many gear line traffic control automatic transmission variable period downshift course control method for use it is characterised in that Keep off in described step 4 two and be down to a gear process control, step 7 three gear is down to two gear process control, step 10 four gear is down to three gears In process control, described downshift controlling cycle variation coefficientβIt is the fixed value setting,β=0.7～1.3；Described joint is strong Degree coefficientkIt is the fixed value setting,k=0.5～0.8；Described delay disengaging time coefficientlIt is the fixed value setting,l=0.8～1.2.