KR102465909B1 - Shift control method for vehicle with dct - Google Patents

Abstract

The present invention includes a slip response determination step in which a controller determines whether a wheel slip response device is operating and whether a shift prohibition request from the wheel slip response device is valid; an overrun determination step of determining, by the controller, whether an engine overrun occurs if an upshift is not performed based on an average vehicle speed of driving wheels of the vehicle and a current gear range in a situation in which the determination condition of the slip response determination step is satisfied; a shift determining step of permitting and starting a shift when the average vehicle speed of non-driven wheels of the vehicle is equal to or greater than a predetermined reference vehicle speed when the determination condition of the overrun determining step is satisfied; When the shift process performed by the shift determining step passes the torque phase, the controller prohibits shifting among other shifts and finishes only the current shift.

Description

Shift control method of DCT vehicle {SHIFT CONTROL METHOD FOR VEHICLE WITH DCT}

The present invention relates to a shift control method for a vehicle equipped with a DCT (DUAL CLUTCH TRANSMISSION), and more particularly, to a shift control technology in a situation where a TRACTION CONTROL SYSTEM (TCS) or an ELECTRONIC STABILITY PROGRAM (ESP) operates.

In a vehicle equipped with a DCT that does not have a separate transmission output shaft speed sensor, wheel speed information is received from the ESP controller or TCS controller, and the shift timing is determined based on this wheel speed. Since the wheel speed is mainly the front wheel speed, As a result, the transmission controller TCU (TRANSMISSION CONTROL UNIT) determines Upshift/Downshift based on the average speed of the front wheels of the vehicle.

However, in a situation where wheel speed fluctuations are excessive, such as on a low-friction road, a situation in which a new shift must be performed during shifting frequently occurs due to a sudden change in wheel speed, which is a reference for shifting.

At this time, if the ECU requests less engine torque for shifting compared to the engine torque required by the ESP or TCS, the ECU controls the engine based on the smaller engine torque of the torque required by both sides of the TCS and TCU. As a result, a driving force reduction phenomenon occurs in the vehicle.

Therefore, the ESP or TCS usually requests the TCU to prohibit shifting during its operation, but if the shift is not made as an exception, the engine overrun causes engine durability to deteriorate and the engine output to be rapidly reduced by the engine protection logic operation. In a special situation where a problem such as deterioration may occur, the TCU performs shifting.

For reference, the engine overrun refers to a situation in which the engine speed is excessively high and enters a red zone, which is a region equal to or higher than the permissible rotational speed of the engine.

The matters described as the background technology of the present invention are only for the purpose of improving the understanding of the background of the present invention, and should not be taken as an admission that they correspond to the prior art already known to those skilled in the art. It will be.

KR 1020170001892 A

In the present invention, in a situation where a DCT vehicle requires shifting to prevent engine overrun during the operation of ESP or TCS on a low-friction road, the driving force of the vehicle can be secured as much as possible while unnecessary shifting is suppressed as much as possible and unavoidable shifting is stably performed. An object of the present invention is to provide a shift control method for a DCT vehicle that can improve driving performance and driving stability of a vehicle by enabling the vehicle to be operated.

The shift control method of the DCT vehicle of the present invention for achieving the above object,

a slip response determination step in which the controller determines whether the wheel slip response device is operating and whether a shift prohibition request from the wheel slip response device is valid;

an overrun determination step of determining, by the controller, whether an engine overrun occurs if an upshift is not performed based on an average vehicle speed of driving wheels of the vehicle and a current gear range in a situation in which the determination condition of the slip response determination step is satisfied;

a shift determining step of permitting and starting a shift when the average vehicle speed of non-driven wheels of the vehicle is equal to or greater than a predetermined reference vehicle speed when the determination condition of the overrun determining step is satisfied;

When the shift process performed by the shift determining step passes the torque phase, the controller prohibits shifting among other shifts thereafter and finishes only the shift in progress.

The method of determining whether an engine overrun occurs in the overrun determining step is to determine that the average vehicle speed of the driving wheels is a situation in which the shift to a higher gear than the current gear in the normal shift pattern or manual shift pattern is performed, and the current gear and the When the engine speed calculated as the driving wheel average vehicle speed belongs to a speed range lower than the lower limit speed of the engine red zone by a predetermined margin speed, it may be determined that an engine overrun occurs.

The present invention may further include a shift level maintenance step of maintaining the current shift level without allowing shifting when the average non-driven wheel speed of the vehicle is less than the reference speed even if the determination condition of the overrun determining step is satisfied. have.

The reference vehicle speed used in the shift determining step is set within a range of 15 to 25 km/h, so that unnecessary shifting may be prevented by performing the shift level maintenance step in a temporary abnormal spin situation of the driving wheels.

Since the DCT mounted in the vehicle does not have an output shaft speed sensor, the controller may receive the wheel speed of the driving wheels from the wheel slip countermeasure device and convert it into an average vehicle speed of the driving wheels for use.

In the present invention, in a situation where a DCT vehicle requires shifting to prevent engine overrun during the operation of ESP or TCS on a low-friction road, the driving force of the vehicle can be secured as much as possible while unnecessary shifting is suppressed as much as possible and unavoidable shifting is stably performed. To improve the driving performance and driving stability of the vehicle.

1 is a diagram illustrating the configuration of a DCT vehicle to which the present invention can be applied;
2 is a flowchart illustrating an embodiment of a shift control method of a DCT vehicle according to the present invention.

Referring to FIG. 1, as an example of a configuration of a DCT vehicle to which the present invention can be applied, power of the engine E is selectively provided to two input shafts I1 and I2 through two clutches CL1 and CL2 of the DCT. and the power shifted in the DCT is provided to the drive wheels (W).

The controller (CLR) is connected to the ECU (Engine Control Unit) to receive information such as engine torque and to make a request to the engine (E) such as torque reduction, etc., and a clutch actuator (CA) that controls the two clutches of the DCT and a gear actuator GA that changes the gear meshing state of the DCT.

The controller (CLR) is configured to receive a signal from an accelerator pedal sensor (APS), configured to receive a rotational speed of each input shaft (I1, I2) of the DCT, etc., and may be a TCU (Transmission Control Unit). have.

The two clutches can be divided into those used to realize the current shift stage and those used to implement the new target shift stage during shifting. Hereinafter, the clutches must be released as the shift progresses The clutch that does this will be referred to as a 'release-side clutch', and the clutch that is gradually engaged to realize a target shift stage will be referred to as an 'engagement-side clutch'.

In addition, according to the classification of the above clutch, the input shaft to which the release-side clutch is connected is referred to as a release-side input shaft, and the input shaft to which the engagement-side clutch is connected is referred to as an engagement-side input shaft.

In addition, hereinafter, 'target shift stage input shaft speed' refers to the rotational speed of the input shaft used to implement the target shift range when the transmission gear of the target shift range is engaged.

On the other hand, the vehicle is equipped with a TCS (Traction Control System), so that when the vehicle has a sudden wheel slip on an icy road or snowy road, the driving force of the vehicle can be secured in an appropriate state by operating a braking device and reducing engine torque. has been

For reference, hereinafter, devices capable of requesting engine torque reduction and shift prohibition in response to rapid wheel slip, such as TCS or ESP, will be collectively referred to as 'wheel slip countermeasure devices'.

Referring to FIG. 2 , in an embodiment of the shift control method of a DCT vehicle according to the present invention, a slip response determination step (S10) in which a controller determines whether a wheel slip response device is operating and whether a shift prohibition request from the wheel slip response device is valid. )Wow; An overrun determination step in which the controller determines whether an engine overrun will occur if an upshift is not performed based on the average vehicle speed of the driving wheels of the vehicle and the current gear range in a situation in which the determination condition of the slip response determination step (S10) is satisfied. (S20) and; a shift determining step (S30) of permitting and starting a shift when the average vehicle speed of non-driven wheels of the vehicle is greater than or equal to a predetermined reference vehicle speed when the determination condition of the overrun determining step (S20) is satisfied; When the shifting process performed by the shift determining step (S30) passes the torque phase, the controller prohibits shifting among other shifts thereafter and finishes only the shift in progress (S40).

That is, in the present embodiment, if the wheel slip response apparatus generates a shift prohibition request and is in operation, if the shift is not made to the upper gear range, there is a risk of engine overrun, even though the shift prohibition request is received, Even if a shift is inevitably performed to a higher gear range and a shift to a new target gear gear is required after the torque phase has elapsed during this shift process, the vehicle is prohibited from shifting during gear shifting and the shift in progress is completed. The driving force of the vehicle can be secured as much as possible while unnecessary shifting is suppressed as much as possible, and unavoidable shifting can be performed stably so as to improve the driving performance and driving stability of the vehicle.

In addition, in this embodiment, even if the determination condition of the overrun determination step (S20) is satisfied, only when the average vehicle speed of non-driven wheels of the vehicle is equal to or greater than the reference vehicle speed, the shift is shifted to a higher gear through the shift determination step (S30) as described above. is performed, and when the average vehicle speed of the non-driven wheels is less than the reference vehicle speed, a shift stage maintaining step (S50) of maintaining the current shift range without allowing shifting is performed.

This is to prevent unnecessary shifting by performing the gear shift stage maintaining step (S50) in a temporary and abnormal spin situation of only the drive wheels, and the reference vehicle speed used in the shift determining step (S30) is 15 to 25 km/h. It can be set within the range.

At this time, the controller may prevent shifting to a higher shift level and maintain the current shift level by updating the target shift level to the current shift level to perform the shift level maintaining step (S50).

On the other hand, there may be several methods for determining whether an engine overrun occurs in the overrun determination step S20, but for example, the average vehicle speed of the driving wheels is shifted to a higher gear than the current gear in the normal shift pattern or manual shift pattern. When it is determined that the situation requires shifting and the engine speed calculated with the current gear stage and the average vehicle speed of the drive wheels falls within a speed range lower than the lower limit speed of the engine red zone by a predetermined margin speed, it is configured to determine that an engine overrun occurs. You will be able to.

In this case, the marginal speed may be set to several hundred RPM lower than the lower limit speed of the engine red zone.

Meanwhile, since the DCT mounted in the vehicle does not have an output shaft speed sensor, the controller is configured to receive the wheel speed of the driving wheels from the wheel slip countermeasure device and convert it into the driving wheel average vehicle speed for use. It is a configuration corresponding to the fact that the DCT of has a separate output shaft speed sensor.

Of course, in the shift management step, the shift is completed by proceeding with the inertia phase after the torque phase of the shifting process in progress, and when this shift is completed, the entire control routine of the present invention is iteratively , it will be possible to respond to additional shifting needs after this shift control.

For reference, in the above, the torque phase refers to a shift section in which the release-side clutch torque is gradually released and the engagement-side clutch torque is gradually increased without changing the engine speed, and the inertia phase is substantially This refers to the gear shift section in which the engine speed changes and is synchronized with the target gear stage input shaft speed.

Although the present invention has been shown and described in relation to specific embodiments, it is known in the art that the present invention can be variously improved and changed without departing from the technical spirit of the present invention provided by the claims below. It will be self-evident to those skilled in the art.

E; engine
CL1, CL2; clutch
I1, I2; input shaft
W; drive wheel
CLR; controller
CA; clutch actuator
GA; gear actuator
APS; accelerator pedal sensor
S10; Slip response judgment stage
S20; Overrun Judgment Stage
S30; shift decision step
S40; gear shift adjustment step
S50; gear shift maintenance stage

Claims (5)

a slip response determination step (S10) in which the controller determines whether the wheel slip response device is operating and whether a shift prohibition request from the wheel slip response device is valid;
An overrun determination step in which the controller determines whether an engine overrun will occur if an upshift is not performed based on the average vehicle speed of the driving wheels of the vehicle and the current gear range in a situation in which the determination condition of the slip response determination step (S10) is satisfied. (S20) and;
a shift determining step (S30) of permitting and starting a shift when the average vehicle speed of non-driven wheels of the vehicle is greater than or equal to a predetermined reference vehicle speed when the determination condition of the overrun determining step (S20) is satisfied;
When the shift process performed by the shift determining step (S30) passes the torque phase, the controller prohibits shifting among other shifts thereafter and finishes only the shift in progress (S40);
including,
In the overrun determination step (S20), the method of determining whether an engine overrun occurs is a situation in which the average vehicle speed of the driving wheels is determined to be shifted to a higher gear than the current gear in the normal shift pattern or manual shift pattern, and Determining that an engine overrun occurs when the engine speed calculated by the shift stage and the average vehicle speed of the driving wheels falls within a speed range lower than the lower limit speed of the engine red zone by a predetermined margin speed
Transmission control method of a DCT vehicle, characterized in that. delete The method of claim 1,
a shift level maintaining step (S50) of maintaining a current shift level without allowing shifting when the average non-driven wheel speed of the vehicle is less than the reference speed even if the determination condition of the overrun determining step (S20) is satisfied;
A shift control method of a DCT vehicle, characterized in that configured to further include. The method of claim 3,
The reference vehicle speed used in the shift determining step (S30) is set within the range of 15 to 25 Km/h, so that unnecessary shifting is prevented by performing the shift level maintenance step (S50) in a temporary abnormal spin situation of the driving wheels.
Transmission control method of a DCT vehicle, characterized in that. According to any one of claims 1 to 4,
The controller is not provided with an output shaft speed sensor in the DCT mounted on the vehicle, so the controller receives the wheel speed of the driving wheels from the wheel slip countermeasure device and converts it into an average vehicle speed of the driving wheels for use.
Transmission control method of a DCT vehicle, characterized in that.

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