KR102030144B1 - Method for controlling shifting of dct vehicle - Google Patents

Abstract

The shift control method of the DCT vehicle according to the present invention includes the steps of the control unit to determine whether the downshifting is required during the inertia driving of the vehicle, the engagement of the N-1 gear is a downshift gear; As a result of performing the checking step, when the engagement of the N-1 gear is completed, the controller predicts the time required for the vehicle speed to reach the vehicle speed required by the N-2 speed shift pattern based on the deceleration of the vehicle. Doing; Calculating, by the controller, a target torque phase time by subtracting a predetermined set inertia time from a predicted required time; After the calculating step, comparing, by the controller, a target torque phase time with a preset set torque phase time; As a result of performing the comparing step, when the target torque phase time is less than the set torque phase time, the control unit performs a torque handover control to engage the engagement side clutch while releasing the release side clutch during the target torque phase time. step; And after the first performing step, when the controller determines that the engine speed is synchronized with the target synchronous speed of the N-1 stage, releasing the N stage gear and engaging the N-2 stage gear. .

Description

DCT vehicle shift control method {METHOD FOR CONTROLLING SHIFTING OF DCT VEHICLE}

The present invention relates to a shift control method of a DCT vehicle to secure a sense of acceleration in a future re-acceleration situation by performing a predicted downshift quickly when a vehicle deceleration occurs in a power-off downshift situation.

Dual clutch transmission (DCT) has two input shafts respectively connected to two clutches, and by arranging the shift gears installed on these two input shafts in an odd and even side, one of the two input shafts is shifted by the hole means. A stage is implemented, and the other is provided to implement an even shift gear.

When the DCT shifts sequentially from one of the gear shifts to the next gear, the DCT is released to the other input shaft to which the next shift gear is coupled while releasing the clutch connected to the input shaft as long as the current gear is engaged. Shift the gear while engaging the clutch.

Accordingly, there is an advantage in that the shift can be made while preventing the torque transmitted to the driving wheel from being completely cut off during the shift.

In general, downshift shifting in a DCT vehicle includes an Inertia Phase section in which the engine speed is synchronized with the input side shaft speed after the torque phase section in which the release clutch torque is switched to the engagement side clutch torque. It goes through

On the other hand, in the power-off situation in which the accelerator pedal is turned off while the vehicle is being driven, the downshift is naturally performed while the vehicle speed decreases. If the same sudden deceleration occurs, the downshift cannot be implemented quickly.

Accordingly, when the acceleration is re-accelerated by the driver, acceleration is performed in a state where the high gear is engaged, whereby a feeling of acceleration decreases due to a low high gear ratio.

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

KR 10-1996-0037452 A

The present invention has been proposed to solve this problem, and in the case of a power off downshift situation, the downshift is performed as quickly as possible when the additional downshift is predicted according to the deceleration of the vehicle, thereby reaccelerating the vehicle. The object of the present invention is to provide a shift control method of a DCT vehicle to secure performance.

The shift control method of the DCT vehicle according to the present invention for achieving the above object is the step of the control unit is required to downshift during the coasting of the vehicle, confirming whether the engagement of the N-1 gear, which is a downshift gearbox is completed; As a result of performing the checking step, when the engagement of the N-1 gear is completed, the controller predicts the time required for the vehicle speed to reach the vehicle speed required by the N-2 speed shift pattern based on the deceleration of the vehicle. Doing; Calculating, by the controller, a target torque phase time by subtracting a predetermined set inertia time from a predicted required time; After the calculating step, comparing, by the controller, a target torque phase time with a preset set torque phase time; As a result of performing the comparing step, when the target torque phase time is less than the set torque phase time, the control unit performs a torque handover control to engage the engagement side clutch while releasing the release side clutch during the target torque phase time. step; And after the first performing step, when the controller determines that the engine speed is synchronized with the target synchronous speed of the N-1 stage, releasing the N stage gear and engaging the N-2 stage gear. .

And a second performing step of performing, by the controller, the torque handover control during the set torque phase time when the target torque phase time is equal to or greater than the set torque phase time as a result of performing the comparing step. The controller may perform the matching step.

The set inertia phase time may be a value calculated based on an engine speed, an N-1 stage target synchronous speed, and a target engine angular acceleration.

In the engaging step, the control unit may be characterized in that the feedback control the clutch torque so that the engine angular acceleration reaches the target engine angular acceleration.

In the matching step, the controller determines that the engine speed is synchronized to the N-1 stage target synchronous speed when the difference between the engine speed and the N-1 stage target synchronous speed during the first set time is less than the set speed. can do.

After the engagement step, the controller starts the N-2 speed shift when the vehicle speed reaches the vehicle speed required by the N-2 speed shift pattern or when the second preset time elapses after the N-2 speed gear is started. It may be characterized in that it further comprises a.

According to the shift control method of the DCT vehicle having the above-described structure, when the deceleration is increased by the brake operation while the DCT vehicle is in the coasting state, the downshift is predicted quickly by predicting the continuous downshift situation. Therefore, it is possible to prevent the acceleration delay when the vehicle is re-accelerated due to the fast downshift.

1 is a flowchart illustrating a shift control method of a DCT vehicle according to an embodiment of the present invention;
2 is a view schematically showing the structure of a DCT vehicle according to an embodiment of the present invention;
3 is a graph showing a vehicle state according to shift control of a DCT vehicle of the present invention;
4 is a graph illustrating a shift pattern of a DCT vehicle according to an exemplary embodiment of the present invention.

Hereinafter, a shift control method of a DCT vehicle according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a flowchart illustrating a shift control method of a DCT vehicle according to an embodiment of the present invention, and FIG. 2 is a view schematically illustrating a structure of a DCT vehicle according to an embodiment of the present invention.

1 to 2, in the shift control method of the DCT vehicle according to the present invention, the control unit 115 determines that downshifting is required during the inertia driving of the vehicle, so that the engagement of the N-1 gear, which is a downshift gearbox, is completed. Step S10; As a result of performing the checking step (S10), when the matching of the N-1 gear is completed, the controller 115 reaches the vehicle speed required by the N-2 speed shift pattern based on the deceleration of the vehicle. Estimating the required time (A) (S20); After the prediction step (S20), the control unit 115 calculates a target torque phase time (B) by subtracting a predetermined set inertia phase time (C) from the estimated time required (A) (S30); After the calculating step (S30), the control unit 115 compares the target torque phase time (B) with a predetermined set torque phase time (B ') (S40); As a result of performing the comparing step (S40), when the target torque phase time (B) is smaller than the set torque phase time (B '), the control unit 115 releases the release side clutch during the target torque phase time (B). A first performing step (S50) of performing a torque handover control for engaging the engagement side clutch; And after the first performing step S50, when the controller 115 determines that the engine speed is synchronized with the N-1 stage target synchronous speed, releasing the N stage gear and engaging the N-2 gear. It may include (S70).

The DCT vehicle of the present invention is composed of a transmission 110 that connects the engine 100 to the main power source and connects the engine 100 to the differential device. Here, the transmission 110 is composed of two clutches and a gearbox as a dual clutch transmission (DCT). The control unit 115 may be a transmission control unit (TCU) for fastening / releasing control of two clutches provided in the transmission 110, and controlling fastening of gears inside the gearbox. The controller 115 may be provided to communicate data with an engine control unit (ECU) that controls the engine 100.

In the present invention, the control unit 115 first senses an accelerator pedal depression amount through an accelerator position sensor (APS) and senses a vehicle speed through a vehicle speed sensor to determine whether the vehicle is in an inertia driving state moving forward in an accelerator pedal state. To judge. For convenience of description, it is described that the vehicle is traveling in N stages.

If the vehicle is in coasting in the N stage, the vehicle speed gradually decreases and approaches the vehicle speed required by the N-1 speed shift pattern. In this case, the controller 115 prepares for downshift predicted by depositing the N-1 gears inside the transmission 110 gearbox. After that, when the vehicle speed reaches the vehicle speed required by the N-1 speed shift pattern, the vehicle is downshifted.

At this time, the control unit 115 receives the deceleration information of the vehicle through the acceleration sensor, and reaches the vehicle speed required by the N-2 speed shift pattern, which is a downshift pattern in which the vehicle speed is continuous, based on the deceleration and the vehicle speed of the vehicle. It can calculate the time required (A) to take.

Here, the deceleration is a value obtained by differentiating the vehicle speed, and may be defined as a speed at which the vehicle speed converges to the N-2 speed shift pattern. Therefore, the larger the deceleration, the shorter the required time A will be predicted.

The controller 115 calculates the target torque phase time B by subtracting the estimated required time A by a predetermined set inertia phase time C (S30).

3 is a graph showing a vehicle state according to the shift control of the DCT vehicle of the present invention. In general, the downshift of the DCT vehicle is followed by a torque phase section in which torque handover control occurs in which the clutch clutch torque rises while the release clutch torque decreases. An Inertia Phase section occurs where the engine speed rises to the target engine speed.

The set inertia phase time (C) is an N-1 stage target synchronous speed which is set by increasing the engine speed to a predetermined target engine angular acceleration (dSlip / dt) slope from the time when the inertia phase section starts. It means the time it takes to reach the point.

Therefore, the set inertia phase time C is calculated based on the engine speed, the N-1 stage target synchronous speed, and the target engine angular acceleration.

When the controller 115 subtracts the required time A predicted through the prediction step S20 by the set inertia phase time C, the torque phase section is performed as shown in FIG. 3. The time that should be calculated is calculated, which is called the target torque phase time (B).

However, when a normal DCT vehicle performs the torque phase for an excessively short time, the torque phase is stably applied to prevent the speed change from deteriorating due to a sudden increase in the engine speed or a shift shock. The set torque phase time B 'is preset to be performed.

Accordingly, the controller 115 compares the target torque phase time B calculated through the calculation step S30 with the set torque phase time B ', and if the target torque phase time B is shorter, the actual torque phase ( By performing the torque handover control during the torque phase section within the target torque phase time B, it is possible to execute a fast downshift even at the expense of shifting feeling (S50).

However, of course, even if the time required for the torque phase section is short, since the vehicle is in the power off state, a large shift shock such as a sudden increase in the engine speed will not occur.

Referring to FIGS. 1 and 2 again, after performing the first performance step S50, an inertia phase is started, and the engine speed is synchronized with the target synchronizing speed of the N-1 stage. When the Inertia Phase) is completed, the controller 115 releases the N-geared gears and deposits the N- 2 -gear gears, thereby quickly preparing for a continuous downshift situation (S70).

On the other hand, according to the present invention, when the target torque phase time (B) is greater than or equal to the set torque phase time (B ') as a result of performing the comparison step (S40), the control unit 115 torques during the set torque phase time (B'). A second performing step S60 of performing handover control may be further included.

In other words, if the deceleration is low because the driver does not decelerate the vehicle, the target torque phase time B is largely calculated by increasing the time A required for the vehicle speed to reach the N-2 speed shift pattern. Can be.

Therefore, when the target torque phase time B is greater than or equal to the set torque phase time B ', the controller 115 performs torque handover control during the set torque phase time B', thereby requiring the torque phase section. It is possible to secure a driving shift feeling while preventing an excessive increase in time.

In addition, in the engagement step (S70) of the present invention, the control unit 115 may be characterized in that the feedback control the clutch torque so that the engine angular acceleration reaches the target engine angular acceleration (dSlip / dt).

Therefore, it is possible to minimize the occurrence of an error in the set inertia phase time (C) by increasing the engine speed to the target engine angular acceleration (dSlip / dt) in the inertia phase section.

In addition, in the matching step (S70), the control unit 115, when the difference between the engine speed and the N-1 stage target synchronous speed during the first set time is less than the set speed, the engine speed is N-1 single target engine speed Can be determined to be motivated.

The set speed may be set to a speed difference at a time point when it is determined that synchronization is completed by determining that the difference between the engine speed and the N-1 stage target synchronous speed does not occur significantly. In particular, by determining whether the engine speed is less than the set speed during the first set time, it is determined that the engine speed synchronization is completed only when the engine speed stably converges to the N-1 stage target synchronous speed.

On the other hand, according to the present invention, after the matching step (S70), the control unit 115 reaches the vehicle speed required by the N-2 speed shift pattern, or the second set time has elapsed since the N-2 gear shift is started. If so, the step of starting the N-2 speed shift (S80); may further include.

4 is a graph illustrating a shift pattern of a DCT vehicle according to an embodiment of the present invention. 1 to 4, since the present invention is an inertia driving situation, the APS sensing value will be 0, and the downshift is performed while the vehicle speed is gradually lowered.

If the N-2 gear is deposited through the above-described engagement step (S70), when the vehicle speed reaches the vehicle speed set in the N-2 speed shift pattern, the downshift can be performed quickly by performing the N-2 speed shift. Can be.

According to the shift control method of the DCT vehicle having the above-described structure, when the deceleration is increased by the brake operation while the DCT vehicle is in the coasting state, the downshift is predicted quickly by predicting the continuous downshift situation. Therefore, it is possible to prevent the acceleration delay when the vehicle is re-accelerated due to the fast downshift.

While the invention has been shown and described with respect to particular embodiments, it will be appreciated that various changes and modifications can be made in the art without departing from the spirit of the invention provided by the following claims. It will be self-evident for those of ordinary knowledge.

S10: Confirmation Step
S20: Prediction Step
S30: calculating stage
S40: comparison step
S50: first performing step
S60: second performance stage
S70: engagement stage
S80: Getting Started
100: engine
105: ECU
110: transmission
115: control unit

Claims (6)

A control unit requesting downshifting during inertia driving of the vehicle to check whether the engagement of the N-1 gear, which is a downshift gear, is completed;
As a result of performing the checking step, when the engagement of the N-1 gear is completed, the controller predicts the time required for the vehicle speed to reach the vehicle speed required by the N-2 speed shift pattern based on the deceleration of the vehicle. Doing;
Calculating, by the controller, a target torque phase time by subtracting a predetermined set inertia phase time from a predicted required time;
Comparing, by the control unit, a target torque phase time with a preset set torque phase time;
As a result of performing the comparing step, when the target torque phase time is less than the set torque phase time, the control unit performs a torque handover control to engage the engagement side clutch while releasing the release side clutch during the target torque phase time. step; And
After the first performing step, when the control unit determines that the engine speed is synchronized to the N-1 stage target synchronous speed, releasing the N stage gear and engaging the N-2 stage gear; Shift control method. The method according to claim 1,
A second performing step of performing, by the control unit, the torque handover control during the set torque phase time when the target torque phase time is equal to or greater than the set torque phase time as a result of performing the comparing step;
After the second performing step, the control unit performs the gear shifting step, characterized in that the DCT vehicle. The method according to claim 1,
The set inertia phase time is a value calculated based on an engine speed, an N-1 stage target synchronous speed, and a target engine angular acceleration. The method according to claim 3,
In the engagement step, the control unit controls the shift of the clutch torque so that the engine angular acceleration reaches the target engine angular acceleration. The method according to claim 3,
In the matching step, the controller determines that the engine speed is synchronized to the N-1 stage target synchronous speed when the difference between the engine speed and the N-1 stage target synchronous speed during the first set time is less than the set speed. Shift control method of a DCT vehicle. The method according to claim 1,
After the engagement step, the controller starts the N-2 speed shift when the vehicle speed reaches the vehicle speed required by the N-2 speed shift pattern or when the second preset time elapses after the N-2 speed gear is started. The shift control method of the DCT vehicle, characterized in that it further comprises.

Images