CN110077408B - A control method for intelligent downshift of automatic transmission vehicle - Google Patents

Abstract

The invention relates to the technical field of vehicles, in particular to an intelligent downshift control method for an automatic-gear vehicle, which comprises a TCU (train control unit), an EMS (energy management system) unit, an engine, a first clutch and a second clutch, wherein the TCU unit calculates torque required by the engine and torque required by the clutch according to the vehicle sliding condition, controls the clutch torque to be combined with a target position, simultaneously provides an engine torque request to the EMS unit, the EMS unit controls the engine to output corresponding engine torque according to the torque request, and the TCU unit calculates the clutch torque and the engine torque through three time periods of a first stage, a second stage and a third stage respectively, so that the engine torque and the clutch torque are matched with each other in real time in the downshift process, the whole vehicle slides and downshifts smoothly, and the comfort of a driver and passengers is improved.

Description

A control method for intelligent downshift of automatic transmission vehicle

technical field

The invention relates to the technical field of vehicles, in particular to a control method for intelligent downshifting of an automatic transmission vehicle.

Background technique

Coasting and downshifting is a common operating condition for dual-clutch transmissions, but if the engine torque control is not appropriate, or the clutch torque control is not appropriate, it will cause a setback, affecting the driver's driving experience and the passenger's riding experience. Therefore, in order to reduce the bumpy feeling, the vehicle needs to be downshifted, which is a relatively complicated process involving the matching of engine torque and transmission clutch torque. . However, in the prior art, the time periods for intelligent downshifting of automatic transmission vehicles are not well connected, so that the entire vehicle cannot run smoothly enough.

SUMMARY OF THE INVENTION

In view of the above technical problems in the prior art, the present invention provides a control method for intelligent downshifting of an automatic transmission vehicle, which can adjust engine torque and clutch torque in real time, so that the vehicle can run smoothly when downshifting.

For achieving the above object, the present invention provides the following technical solutions:

Provided is a control method for intelligent downshifting of an automatic transmission vehicle, comprising a TCU unit, an EMS unit, an engine, a first clutch and a second clutch, wherein the TCU unit first calculates the torque required by the engine and the torque required by the clutch according to the actual coasting of the vehicle, The TCU unit controls the clutch torque to be combined to the target position. The TCU unit simultaneously submits an engine torque request to the EMS unit. The EMS unit controls the engine to output the corresponding engine torque according to the torque request. The calculation steps of the engine torque and the clutch torque are as follows:

A. When changing from an even-numbered gear to an odd-numbered gear, since the engine speed and the second clutch speed are in a synchronized state, first calculate the second clutch torque, including the following calculation steps:

1) The first stage: before and including time point a, calculate the second clutch torque and engine torque

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

In this stage, the engine speed is not synchronized with the first clutch speed, the engine speed is kept synchronized with the second clutch speed, and this stage is in the process of switching the second clutch torque to the first clutch torque, and the time point a is the starting point, time point b end point,

i) When it is time point b, since time point b is a critical time point, the second clutch is completely disengaged at this time, the first clutch completely takes over the engine torque, and the second clutch speed is still consistent with the engine speed, so , calculate the first clutch torque and engine torque;

ii) In the process of switching from time point a to time point b, it is enough to control the coupling speed of the first clutch. In the process of actively controlling the torque of the first clutch, the TCU unit needs to coordinate the starting torque at any time. At this time, the second clutch The torque cannot be combined too little, and a certain torque must be maintained, otherwise the acceleration will be discontinuous, and considering the engine response speed factor, the second clutch torque must match the engine torque at this stage, and must be combined according to the appropriate combination speed, the second clutch In the separate type, a certain torque trend is maintained, and the second clutch torque and the engine torque are calculated. At this time, the TCU unit requests the engine torque in real time according to the calculated value;

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point, the engine torque is completely taken over by the first clutch, and the first clutch torque needs to be maintained in order to preserve the acceleration dwv/dt. The torque transmitted by the first clutch remains unchanged, and the engine speed should be gradually synchronized to the speed of the first clutch;

i) At time point c, since time point c is a critical time point, the first clutch speed is still synchronized with the engine speed, and the first clutch torque and the engine torque are calculated;

ii) When switching from time point b to time point c, keep the first clutch torque unchanged, but in order to synchronize the engine speed with the first clutch speed, the engine torque needs to be increased. At this time, a target engine speed curve can be demarcated, through Request to control the engine torque to achieve the purpose, but must control the engine torque to turn from time point b to time point c. At this time, the three stages are completed, and each stage has a clear control method. Control according to the above stages, the whole vehicle coasts and downshifts can pass smoothly;

B. When changing from an odd-numbered gear to an even-numbered gear, since the engine speed and the second clutch speed are in a synchronized state, the second clutch torque is calculated first, including the following calculation steps:

1) The first stage: before and including time point a, calculate the first clutch torque and engine torque

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

In this stage, the engine speed is not synchronized with the second clutch speed, the engine speed is kept synchronized with the first clutch speed, and this stage is in the process of switching the second clutch torque to the first clutch torque, and the time point a is the starting point, time point b end point,

i) When it is time point b, since time point b is a critical time point, the first clutch is completely disengaged, the second clutch completely takes over the engine torque, and the first clutch speed is still consistent with the engine speed, so Calculate second clutch torque and engine torque;

ii) When switching from time point a to time point b, it is enough to control the coupling speed of the second clutch. The TCU unit needs to coordinate the starting torque at any time in the process of actively controlling the torque of the second clutch. At this time, the first clutch The torque cannot be combined too little, and a certain torque must be maintained, otherwise the acceleration will be discontinuous, and considering the engine response speed factor, the first clutch torque must match the engine torque at this stage, and must be combined according to the appropriate combination speed, the first clutch In the separate type, a certain torque trend is maintained, and the first clutch torque and the engine torque are calculated. At this time, the TCU unit requests the engine torque in real time according to the calculated value;

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point, the engine torque is completely taken over by the second clutch, and the second clutch torque needs to be maintained in order to preserve the acceleration dwv/dt. The torque transmitted by the second clutch remains unchanged. At this time, the engine speed should be gradually synchronized to the second clutch speed.

i) At time point c, since time point c is a critical time point, the second clutch speed is still synchronized with the engine speed, and the second clutch torque and the engine torque are calculated;

ii) In the process of switching from time point b to time point c, the second clutch torque is kept unchanged, but in order to synchronize the engine speed with the second clutch speed, the engine torque needs to be increased. At this time, a target engine speed curve can be calibrated. Request to control the engine torque to achieve the purpose, but must control the engine torque to turn from time point b to time point c. At this time, the three stages are completed, and each stage has a clear control method. Control according to the above stages, the whole vehicle coasts and downshifts can pass smoothly;

Among them, A. When the even-numbered gear is lowered to the odd-numbered gear, the following calculation steps are included:

1) The first stage: before and including time point a, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2:

Calculation process:

By i2*Tc2-Tr=Jv*dwv/dt,

Tc2=(Jv*dwv/dt+Tr)/i2 is obtained, and the calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt:

Calculation process:

From Te-Tc2=Je*dwe/dt and dwe/dt=i2*dwv/dt

It is obtained that Te=Tc2+Je*i2*dwv/dt=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt,

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

i) When it is time point b, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation process: from i1*Tc1-Tr=Jv*dwv/dt,

Get Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv/dt,

Calculation process:

From Te-Tc1=Je*dwe/dt and dwe/dt=i2*dwv/dt

Obtain Te=Tc1+Je*dwe/dt=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv/dt;

ii) When switching from time point a to time point b, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr-i1*Tc1)/i2,

calculation process,

By i2*Tc2+i1*Tc1-Tr=Jv*dwv/dt

Get Tc2=(Jv*dwv/dt+Tr-i1*Tc1)/i2;

Calculation formula of engine torque: Te=Je*i2*dwv/dt+Tc1+(Jv*dwv/dt+Tr–i1*Tc1)/i2,

From Te-Tc2-Tc1=Je*dwe/dt and dwe/dt=i2*dwv/dt

It is obtained that Te=Je*dwe/dt+Tc1+Tc2

=Je*i2*dwv/dt+Tc1+(Jv*dwv/dt+Tr–i1*Tc1)/i2

Among them, Tc1 and Tc2 at this stage are obtained by the above calculation, which are known quantities respectively,

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point

i) At time point c, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation process: from i1*Tc1-Tr=Jv*dwv/dt,

Get Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt,

Calculation process:

From Te-Tc1=Je*dwe/dt and dwe/dt=i1*dwv/dt

Obtain Te=Tc1+Je*i1*dwv/dt=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt;

ii) When switching from time point b to time point c, keep the first clutch torque unchanged, and control the engine torque from time point b Te=(Jv*dwv/dt+Tr)/i1+i2*Je* Te from dwv/dt to time point c=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt.

In all the above calculation processes, Te is the engine torque; Tc1 is the first clutch torque; Tc2 is the second clutch torque; Je is the engine inertia; Jv is the vehicle inertia; dwe/dt is the engine acceleration; dwv/dt is the vehicle Acceleration, i2 is the transmission ratio of even-numbered gears; i1 is the transmission ratio of odd-numbered gears; Tr is the resistance of the whole vehicle, and Jv, i2, i2, Tr, dwv/dt, and Je are all known quantities.

Among them, B. When the odd-numbered gear is lowered to the even-numbered gear, the following calculation steps are included:

1) The first stage: before and including time point a, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1:

Calculation process:

By i1*Tc1-Tr=Jv*dwv/dt,

It is obtained that Tc1=(Jv*dwv/dt+Tr)/i1, the calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt:

Calculation process:

From Te-Tc1=Je*dwe/dt and dwe/dt=i1*dwv/dt

It is obtained that Te=Tc1+Je*i1*dwv/dt=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt,

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

i) When it is time point b, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

Calculation process: from i2*Tc2-Tr=Jv*dwv/dt,

Get Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+i1*Je*dwv/dt,

Calculation process:

From Te-Tc2=Je*dwe/dt and dwe/dt=i1*dwv/dt

It is obtained that Te=Tc2+Je*dwe/dt=(Jv*dwv/dt+Tr)/i2+i1*Je*dwv/dt;

ii) When switching from time point a to time point b, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr-i2*Tc1)/i1,

calculation process,

By i1*Tc1+i2*Tc2-Tr=Jv*dwv/dt

Get Tc1=(Jv*dwv/dt+Tr-i2*Tc1)/i1;

Calculation formula of engine torque: Te=Je*i1*dwv/dt+Tc2+(Jv*dwv/dt+Tr–i2*Tc2)/i1,

From Te-Tc1-Tc2=Je*dwe/dt and dwe/dt=i1*dwv/dt

It is obtained that Te=Je*dwe/dt+Tc2+Tc1

=Je*i1*dwv/dt+Tc2+(Jv*dwv/dt+Tr–i2*Tc2)/i1

Among them, Tc1 and Tc2 at this stage are obtained by the above calculation, which are known quantities respectively,

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point

i) At time point c, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

Calculation process: from i2*Tc2-Tr=Jv*dwv/dt,

Get Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt,

Calculation process:

From Te-Tc2=Je*dwe/dt and dwe/dt=i2*dwv/dt

Obtain Te=Tc2+Je*i2*dwv/dt=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt;

ii) When switching from time point b to time point c, keep the first clutch torque unchanged, and control the engine torque from time point b Te=(Jv*dwv/dt+Tr)/i2+i1*Je* Te from dwv/dt to time point c=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt.

In all the above calculation processes, Te is the engine torque; Tc1 is the first clutch torque; Tc2 is the second clutch torque; Je is the engine inertia; Jv is the vehicle inertia; dwe/dt is the engine acceleration; dwv/dt is the vehicle Acceleration, i2 is the transmission ratio of even-numbered gears; i1 is the transmission ratio of odd-numbered gears; Tr is the resistance of the whole vehicle, and Jv, i2, i2, Tr, dwv/dt, and Je are all known quantities.

Beneficial effects of the present invention:

The TCU unit first calculates the torque required by the engine and the torque required by the clutch according to the actual vehicle coasting situation. The TCU unit controls the clutch torque to be combined to the target position. The TCU unit simultaneously submits an engine torque request to the EMS unit, and the EMS unit controls the engine to output the corresponding engine according to the torque request. Torque, the TCU unit calculates the clutch torque and the engine torque through the three time periods of the first stage, the second stage and the third stage respectively, so that the engine torque and the clutch torque are matched in real time during the downshift process, and then the whole vehicle is coasted and downshifted. It can pass smoothly and improve the comfort of the driver and passengers.

Description of drawings

FIG. 1 is a schematic diagram of the working state of the clutch for lowering the 4th gear to the 3rd gear according to the first embodiment.

FIG. 2 is a schematic diagram of the working state of the clutch for lowering the third speed to the second speed according to the first embodiment.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

Example 1

A method for controlling intelligent downshifting of an automatic transmission vehicle in this embodiment includes a TCU unit, an EMS unit, an engine, a first clutch, and a second clutch. The TCU unit first calculates the torque required by the engine and the required torque of the clutch according to the actual coasting of the vehicle. When the torque is required, the TCU unit controls the clutch torque to be combined to the target position. The TCU unit simultaneously submits an engine torque request to the EMS unit, and the EMS unit controls the engine to output the corresponding engine torque according to the torque request. The calculation steps of the engine torque and the clutch torque are as follows:

When shifting from 4th gear to 3rd gear, the TCU unit includes the following calculation steps:

1) The first stage: before and including time point a, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt;

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

i) When it is time point b, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv/dt;

ii) When switching from time point a to time point b, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr-i1*Tc1)/i2;

Calculation formula of engine torque: Te=Je*i2*dwv/dt+Tc1+(Jv*dwv/dt+Tr–i1*Tc1)/i2;

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point

i) At time point c, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt;

ii) During the process of switching from time point b to time point c, keep the first clutch torque unchanged, and control the engine torque Te=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv at time point b /dt goes to the engine torque Te at time point c = (Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt,

Among them, Te is the engine torque; Tc1 is the first clutch torque; Tc2 is the second clutch torque; Je is the engine inertia; Jv is the vehicle inertia; dwe/dt is the engine acceleration; dwv/dt is the vehicle acceleration, and i2 is an even number gear ratio; i1 is the odd gear ratio; Tr is the vehicle resistance, and Jv, i2, i2, Tr, dwv/dt, and Je are all known quantities.

Explanation of Figure 1:

Figure 1 is a diagram of the working state of the clutch when the 4th gear is lowered to the 3rd gear. As shown in Figure 1, before (1) time point a, the current gear is the 4th gear, and it has not yet been downshifted. Therefore, the first clutch torque and the second The clutch torques are all in the current gears. At this time, the second clutch is taking over the 4th gear. Therefore, the second clutch torque is above the first clutch torque, and the first clutch speed and the second clutch speed are both decreased synchronously to maintain the speed of deceleration. trend;

(2) Time point a to time b is the process of switching the second clutch torque to the first clutch torque and the process of switching the second clutch torque to the first clutch torque, therefore, both of them have a downward trend and an upward trend respectively to achieve required torque;

(3) From time point b to time point c, the first clutch completely takes over the engine torque. Therefore, the first clutch torque is above the second clutch torque, and in order to keep the vehicle acceleration unchanged, the first clutch torque is kept unchanged.

Example 2

A method for controlling intelligent downshifting of an automatic transmission vehicle in this embodiment includes a TCU unit, an EMS unit, an engine, a first clutch, and a second clutch. The TCU unit first calculates the torque required by the engine and the required torque of the clutch according to the actual coasting situation of the vehicle. When the torque is required, the TCU unit controls the clutch torque to be combined to the target position. The TCU unit simultaneously submits an engine torque request to the EMS unit, and the EMS unit controls the engine to output the corresponding engine torque according to the torque request. The calculation steps of the engine torque and the clutch torque are as follows:

When shifting from 3rd gear to 2nd gear, the TCU unit includes the following calculation steps:

When changing from an odd-numbered gear to an even-numbered gear, the following calculation steps are included:

1) The first stage: before and including time point a, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt;

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

i) When it is time point b, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr/i2+i1*Je*dwv/dt;

ii) When switching from time point a to time point b, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr-i2*Tc2)/i1;

Calculation formula of engine torque: Te=Je*i1*dwv/dt+Tc2+(Jv*dwv/dt+Tr–i2*Tc2)/i1;

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point

i) At time point c, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt;

ii) During the process of switching from time point b to time point c, keep the second clutch torque unchanged, and control the engine torque at time point b to be transferred to the engine torque at time point c,

Among them, Te is the engine torque; Tc1 is the first clutch torque; Tc2 is the second clutch torque; Je is the engine inertia; Jv is the vehicle inertia; dwe/dt is the engine acceleration; dwv/dt is the vehicle acceleration, and i2 is an even number gear ratio; i1 is the odd gear ratio; Tr is the vehicle resistance, and Jv, i2, i2, Tr, dwv/dt, and Je are all known quantities.

Explanation of Figure 2:

Figure 2 is a diagram of the working state of the clutch when the 3rd gear is lowered to the 2nd gear. As shown in Figure 2, (1) Before time point a, the front gear is the 3rd gear, and it has not yet been downshifted. Therefore, the first clutch torque and the second The clutch torques are all in the current gear. At this time, the first clutch is taking over the 4th gear. Therefore, the first clutch torque is above the second clutch torque, and the second clutch speed and the first clutch speed are both reduced in synchronization to maintain the speed reduction. trend;

(2) Time point a to time b are the process of switching the first clutch torque to the second clutch torque and the process of switching the first clutch torque to the second clutch torque, therefore, both of them produce a downward trend and an upward trend respectively to achieve required torque;

(3) From time point b to time point c, the second clutch completely takes over the engine torque. Therefore, the second clutch torque is above the first clutch torque, and in order to keep the vehicle acceleration unchanged, the second clutch torque is kept unchanged.

Example 3

In this embodiment, a method for controlling intelligent downshifting of an automatic transmission vehicle includes a TCU unit, an EMS unit, an engine, a first clutch and a second clutch. The TCU unit first calculates the torque required by the engine and the clutch according to the actual coasting situation of the vehicle. The required torque, the TCU unit controls the clutch torque to be combined to the target position, the TCU unit simultaneously requests the engine torque to the EMS unit, and the EMS unit controls the engine to output the corresponding engine torque according to the torque request. The calculation steps of the engine torque and the clutch torque are as follows:

When changing from 2nd gear to 1st gear, the TCU unit includes the following calculation steps:

1) The first stage: before and including time point a, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt;

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

i) When it is time point b, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv/dt;

ii) When switching from time point a to time point b, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr-i1*Tc1)/i2;

Calculation formula of engine torque: Te=Je*i2*dwv/dt+Tc1+(Jv*dwv/dt+Tr–i1*Tc1)/i2;

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point

i) At time point c, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt;

ii) During the process of switching from time point b to time point c, keep the first clutch torque unchanged, and control the engine torque Te=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv at time point b /dt goes to the engine torque Te at time point c = (Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt,

Among them, Te is the engine torque; Tc1 is the first clutch torque; Tc2 is the second clutch torque; Je is the engine inertia; Jv is the vehicle inertia; dwe/dt is the engine acceleration; dwv/dt is the vehicle acceleration, and i2 is an even number gear ratio; i1 is the odd gear ratio; Tr is the vehicle resistance, and Jv, i2, i2, Tr, dwv/dt, and Je are all known quantities.

Example 4

A method for controlling intelligent downshifting of an automatic transmission vehicle in this embodiment includes a TCU unit, an EMS unit, an engine, a first clutch, and a second clutch. The TCU unit first calculates the torque required by the engine and the required torque of the clutch according to the actual coasting situation of the vehicle. When the torque is required, the TCU unit controls the clutch torque to be combined to the target position. The TCU unit simultaneously submits an engine torque request to the EMS unit, and the EMS unit controls the engine to output the corresponding engine torque according to the torque request. The calculation steps of the engine torque and the clutch torque are as follows:

When shifting from 5th gear to 4th gear, the TCU unit includes the following calculation steps:

1) The first stage: before and including time point a, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt;

2) The second stage: between time point a and time point b and including time point b, time point b is the critical point

i) When it is time point b, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr/i2+i1*Je*dwv/dt;

ii) When switching from time point a to time point b, calculate the first clutch torque and engine torque

The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr-i2*Tc2)/i1;

Calculation formula of engine torque: Te=Je*i1*dwv/dt+Tc2+(Jv*dwv/dt+Tr–i2*Tc2)/i1;

3) The third stage: between time point b and time point c and including time point c, time point c is the critical point

i) At time point c, calculate the second clutch torque and engine torque

The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2;

The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt;

ii) During the process of switching from time point b to time point c, keep the second clutch torque unchanged, and control the engine torque at time point b to be transferred to the engine torque at time point c,

Among them, Te is the engine torque; Tc1 is the first clutch torque; Tc2 is the second clutch torque; Je is the engine inertia; Jv is the vehicle inertia; dwe/dt is the engine acceleration; dwv/dt is the vehicle acceleration, and i2 is an even number gear ratio; i1 is the odd gear ratio; Tr is the vehicle resistance, and Jv, i2, i2, Tr, dwv/dt, and Je are all known quantities.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that , the technical solutions of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims (1)

1. a control method for intelligent downshifting of an automatic vehicle, characterized in that: comprising a TCU unit, an EMS unit, an engine, a first clutch and a second clutch, the TCU unit first calculates the required torque of the engine and The torque required by the clutch, the TCU unit controls the clutch torque to be combined to the target position, the TCU unit simultaneously submits an engine torque request to the EMS unit, and the EMS unit controls the engine to output the corresponding engine torque according to the torque request. The calculation steps of engine torque and clutch torque are as follows: A. When changing from an even-numbered gear to an odd-numbered gear, the following calculation steps are included: 1) The first stage: before and including time point a, calculate the second clutch torque and engine torque, The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2, The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt; 2) The second stage: between time point a and time point b and including time point b, time point b is a critical point, i) When it is time point b, calculate the first clutch torque and engine torque, The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1, The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv/dt; ii) When switching from time point a to time point b, calculate the second clutch torque and engine torque, The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr-i1*Tc1)/i2, Calculation formula of engine torque: Te=Je*i2*dwv/dt+Tc1+(Jv*dwv/dt+Tr–i1*Tc1)/i2; 3) The third stage: between time point b and time point c and including time point c, time point c is a critical point, i) When it is time point c, calculate the first clutch torque and engine torque, The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1, The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt; ii) During the process of switching from time point b to time point c, keep the first clutch torque unchanged, and control the engine torque Te=(Jv*dwv/dt+Tr)/i1+i2*Je*dwv at time point b /dt to the engine torque Te at time point c = (Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt; B. When changing from an odd-numbered gear to an even-numbered gear, the following calculation steps are included: 1) The first stage: before and including time point a, calculate the first clutch torque and engine torque, The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr)/i1, The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i1+Je*i1*dwv/dt; 2) The second stage: between time point a and time point b and including time point b, time point b is a critical point, i) When it is time point b, calculate the second clutch torque and engine torque, The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2, The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+i1*Je*dwv/dt; ii) When switching from time point a to time point b, calculate the first clutch torque and engine torque, The calculation formula of the first clutch torque is: Tc1=(Jv*dwv/dt+Tr-i2*Tc2)/i1, Calculation formula of engine torque: Te=Je*i1*dwv/dt+Tc2+(Jv*dwv/dt+Tr–i2*Tc2)/i1; 3) The third stage: between time point b and time point c and including time point c, time point c is a critical point, i) at time point c, calculate the second clutch torque and the engine torque, The calculation formula of the second clutch torque is: Tc2=(Jv*dwv/dt+Tr)/i2, The calculation formula of engine torque is: Te=(Jv*dwv/dt+Tr)/i2+Je*i2*dwv/dt; ii) During the process of switching from time point b to time point c, keep the second clutch torque unchanged, and control the engine torque at time point b to be transferred to the engine torque at time point c, Among them, Te is the engine torque; Tc1 is the first clutch torque; Tc2 is the second clutch torque; Je is the engine inertia; Jv is the vehicle inertia; dwe/dt is the engine acceleration; dwv/dt is the vehicle acceleration, and i2 is an even number gear ratio; i1 is the odd gear ratio; Tr is the vehicle resistance, and Jv, i1, i2, Tr, dwv/dt, and Je are all known quantities.

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