KR20180054991A - Shifting control method for vehicles with dual clutch transmission - Google Patents

Abstract

The present invention relates to a technology for implementing a rapid gear-shift and a direct connection by quickly performing down shifting when sudden acceleration is requested in response to a manual shift. The method according to the present invention includes: determining whether a power-on manual downshift condition is satisfied; slightly reducing release-side clutch torque to allow an engine rotational speed to start rising toward an engagement-side input shaft speed when the shift condition is satisfied; requesting the rising of engine torque to increase the engine rotational speed based on a target engine speed change rate, so that the engine rotational speed is synchronized with the engagement-side input shaft speed after the engine rotational speed starts to rise; and terminating the shifting by increasing the engagement-side clutch torque after the engine rotational speed and the input-side input shaft speed are synchronized.

Description

TECHNICAL FIELD [0001] The present invention relates to a shift control method for a DCT vehicle,

The present invention relates to a shift control method for a DCT vehicle in which a downshift is performed more quickly when a sudden acceleration is requested in response to a manual shift, thereby realizing a quick shifting feeling and direct feeling.

Manual transmission in an automatic transmission vehicle can be operated by operating the shift lever when the driver desires to directly operate the shift pattern. If the driver feels a sporty driving feeling and deceleration is required, such as a downhill driving situation of the vehicle, .

In such a vehicle system, the engine (motor) generates power and the transmission transmits its power to the wheels. The engine (motor) is driven by the driver's will, i.e., the accelerator pedal opening and the brake pedal opening, The degree of acceleration or deceleration is determined. Therefore, the basis for judging the engine itself is equal to the power component due to the driver's will.

However, depending on the shift state, the driver's torque demand may be limited, which may be insufficient for performing the shift control. Further, in the manual shift state, since the shift response expected by the driver may require a more sporty sensibility, there is a case in which the responsiveness is required to be faster than the accelerator pedal opening degree.

It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present invention and is not to be construed as an admission that the prior art is known to those skilled in the art.

KR 10-2014-0034548 A

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a DCT vehicle shift control method for rapidly shifting a downshift in response to a sudden acceleration demand in accordance with a manual shift, have.

According to an aspect of the present invention, there is provided a shift-condition determining method comprising: determining a shift-condition determining step of determining whether a controller satisfies a power-on manual downshift shift condition; A first synchronous control step of controlling, when the shift condition is satisfied, the controller partially reducing the releasing-side clutch torque so that the engine rotational speed starts to rise toward the engaging-side input shaft speed; After the start of the increase in the engine rotational speed in the first synchronous control step, the controller requests the engine torque to rise so that the engine rotational speed increases based on the target engine speed change rate, and controls the engine rotational speed to be synchronized with the engagement- A second synchronization control step And a shift ending step of causing the controller to increase the engagement-side clutch torque to end the shift after synchronization of the engine rotation speed and the engagement-side input shaft speed.

The requested engine torque requested to be raised in the second synchronous control step may be determined to be a larger value among the target assist engine torque determined by the following equation and the target engine torque calculated by reflecting the running state of the vehicle.

Te_target_assist = min (Tc_rel, Te_target) + Je * {d (Ne-Ni_app) / dt + d (Ni_app) / dt}

In the second synchronous control step, feedback control of the release-side clutch torque may be prohibited in a period in which the engine torque is requested to rise based on the required engine torque.

In the second synchronization control step, when the difference between the engine rotation speed and the engagement-side input shaft speed is equal to or greater than the set value in response to the request for increasing the engine torque, the requested engine torque required for the increase can be controlled to be reduced.

In the second synchronization control step, the predetermined engine torque reduction amount is added to the previous required engine torque, and the requested engine torque is controlled so as to be reduced so that the required engine torque reaches the target engine torque.

According to the present invention, when the driver shifts downshifting in a manual mode with an accelerating intention, the engine torque is upwardly controlled on the basis of the target engine acceleration, which is higher than the engine torque by the accelerator pedal, The vehicle is shifted downshifting more quickly to the lower end. Thus, a quick shifting feeling and direct feeling are realized, so that the acceleration of the vehicle is quickly sensed, thereby improving the shift response of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the entire structure of a power train of a vehicle equipped with a DCT applicable to the present invention. Fig.
2 is a view showing a shift control flow of a DCT vehicle according to the present invention.
3 is a diagram for explaining an operation state by the shift control method of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a configuration of a DCT vehicle applicable to the present invention. Briefly describing each constituent element shown in the figure, a coupling-side clutch and a release-side clutch, of two clutches provided in the DCT, are denoted by CL1 and CL2 And the coupling clutch actuator and the release clutch actuator for operating the coupling clutch actuator and the releasing clutch actuator are denoted by the reference numerals CLA1 and CLA2, respectively, and the coupling-side input shaft and the releasing-side input shaft are denoted by reference numerals of INPUT1 and INPUT2, respectively. However, this is only for convenience of understanding of the present invention, and the coupling side and the releasing side may be changed depending on the clutch which forms the current speed change stage and the clutch for forming the target speed change stage.

The shift control method for a DCT vehicle according to the present invention can be largely configured to include a shift condition determination step, a first synchronization control step, a second synchronization control step, and a shift end step.

Referring to FIGS. 2 and 3, more specifically, in the shifting condition determination step, the controller can determine whether the power-on manual downshift shifting condition is satisfied.

For example, in a vehicle capable of selectively shifting between an automatic shift mode and a manual shift mode, the downshift shift operation is detected in the negative shift mode in accordance with the driver's will in the manual shift mode, If it is detected that the value is greater than the predetermined value, it can be determined that the power-on manual downshifting condition is satisfied.

In the first synchronous control step, when the shift condition is satisfied, the controller can reduce the release side clutch torque to some extent and control the engine rotational speed to start rising toward the input side input shaft speed.

That is, when the release side clutch torque is partially reduced as shown in Fig. 3, the slip amount of the release side clutch increases, and the engine rotation speed that has rotated in synchronism with the release side input shaft speed starts to rise at a slope different from the release side input shaft speed .

In the second synchronization control step, after the engine rotation speed is started to rise in the first synchronization control step, the controller requests the engine torque to rise so that the engine rotation speed is increased based on the target engine speed change rate, Side input shaft speed.

That is, as shown in FIG. 3, in the conventional case, the engine rotation speed is controlled to increase through the reaction force of the release clutch. On the other hand, in the present invention, the engine rotation speed is rapidly increased through the assist control for increasing the engine torque, Side input shaft speed.

Then, in the shift end step, after the synchronization of the engine rotation speed and the engagement-side input shaft speed, the controller can increase the engagement-side clutch torque to end the shift.

For example, when the engagement of the engagement side gear is completed after the engagement of the engine rotation speed and the engagement side input shaft speed is completed and the engagement side clutch torque exceeds the reference value, the engagement side clutch torque is raised and the release side clutch torque is lowered The shift can be performed through the torque cross control.

That is, according to the above-described configuration, when the driver shifts downshifting in the manual mode with an accelerating intention, the engine torque is upwardly controlled based on the target engine acceleration further upward in relation to the engine torque by the accelerator pedal Speed downshift to the low-speed side, thereby realizing a feeling of quick shifting and direct connection, and thus the acceleration of the vehicle can be felt quickly.

On the other hand, as described above, in the present invention, in order to quickly increase the engine rotation speed, the engine torque is requested to be raised in the second synchronous control step. At this time, the required engine torque requested to be raised is the target assist torque The engine torque and the target engine torque calculated by reflecting the running state of the vehicle can be determined to be a large value.

Te_target_assist = min (Tc_rel, Te_target) + Je * {d (Ne-Ni_app) / dt + d (Ni_app) / dt}

Te_actual = max (Te_target_assist, Te_target)

Te_target_assist: Target assist engine torque

Te_target: Target engine torque

Te_actual: Request engine torque

Tc_rel: release side clutch torque

Ne: Engine speed

Ni_app: Coupling-side input shaft speed

Je: Engine rotation inertia

At this time, the target engine torque is a target engine torque based on an output value (APS opening amount, engine speed, shift information, and the like) that reflects the running state of the vehicle, which may be a set value.

That is, the target engine speed change rate (target engine speed slope) is calculated as a function of the smaller of the release side clutch torque and the target engine torque, the engine rotational inertia, the slip change rate of the engagement side clutch, and the change rate of the input side input shaft speed The target assist engine torque can be calculated and the calculated target assist engine torque can be compared with the target engine torque and a larger one of them can be determined as the required engine torque to control the engine torque to rise.

However, in some cases, the target assist engine torque calculated as described above may be directly determined as the required engine torque, and the engine torque may be controlled to rise.

In addition, during the second synchronization control step of increasing the engine torque as described above, it is possible to control the feedback control of the release side clutch torque to be prohibited, particularly in the interval in which the engine torque is requested to be increased.

That is, the reason why the engine torque is controlled to be raised by the required engine torque is to rapidly increase the engine rotation speed to synchronize the engine rotation speed with the input side input shaft speed more quickly. However, if the releasing-side clutch torque is controlled so as to prevent the shifting shock in the section in which the engine torque is requested to be increased based on the required engine torque, the engine rotation speed is relatively slowed down and the time synchronized with the engaging- The feedback control of the releasing-side clutch torque with respect to the engine rotational speed can be prohibited in the section where the engine torque is requested to rise.

However, after the period in which the engine torque is requested to be increased based on the required engine torque, the release side clutch torque is allowed to rise by allowing the feedback control of the release side clutch torque so that the release side clutch torque It is also possible to perform control so that normal torque crossing control of the engagement side clutch torque is possible.

In addition, in the second synchronous control step described above, it is possible to control the requested engine torque to be lowered when the difference between the engine rotation speed and the engagement-side input shaft speed exceeds the set value in response to the engine torque increase request .

Specifically, it is possible to control to reduce the required engine torque until the required engine torque reaches the target engine torque by adding a constant engine torque reduction amount to the previous required engine torque calculated in response to the engine torque increase request.

For example, when the difference between the engine rotation speed and the engagement-side input shaft speed is -50 RPM or more, it is possible to enter the control for reducing the required engine torque.

Hereinafter, the shift control process of the present invention will be described with reference to FIG. 2 and FIG.

First, the downshift operation is performed from the (-) side to the (-) end of the shift lever in the manual mode, and it is determined whether the APS sensor is above the reference value and whether the power-on manual downshift shift condition is satisfied.

When the shift condition is satisfied, the release side clutch torque is controlled to be partially reduced to determine whether the difference between the engine rotational speed and the input side input shaft speed exceeds the reference value (S20).

As a result of the determination in step S20, when the reference value is exceeded, the target assist engine torque is calculated based on the target engine speed change rate, and the larger of the calculated target assist engine torque and the target engine torque is determined as the required engine torque, , The engine rotation speed is rapidly raised based on the target engine speed change rate (S30).

Then, it is determined whether the difference between the engine rotational speed and the input-side input shaft speed is equal to or greater than the reference value and the slip amount of the coupling-side clutch is determined (S40).

If it is determined in step S40 that the difference between the engine rotational speed and the input-side input shaft speed is equal to or greater than the reference value, the required engine torque is controlled to be reduced until the required engine torque reaches the target engine torque (S50).

Then, when engagement of the engagement-side gear is completed and the engagement-side clutch torque exceeds the set value (S60), the engagement-side clutch torque is increased and the release-side clutch torque is lowered, (S70).

As described above, according to the present invention, when the driver shifts downshifting in a manual mode with an acceleration will, by upwardly controlling the engine torque based on the target engine acceleration further upward in relation to the engine torque by the accelerator pedal, Shifting downshift to the lower end quickly, and realizing a feeling of quick shifting feeling and direct connection, so that the acceleration of the vehicle is quickly sensed, thereby improving the shift response of the vehicle.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limited to the specific embodiments set forth herein; rather, .

1:
CL1: Coupling-side clutch CL2: Release-side clutch

Claims (5)

A shifting condition judging step of judging whether the controller satisfies a power-on manual down shift shifting condition;
A first synchronous control step of controlling, when the shift condition is satisfied, the controller partially reducing the releasing-side clutch torque so that the engine rotational speed starts to rise toward the engaging-side input shaft speed;
After the start of the increase in the engine rotational speed in the first synchronous control step, the controller requests the engine torque to rise so that the engine rotational speed increases based on the target engine speed change rate, and controls the engine rotational speed to be synchronized with the engagement- A second synchronization control step And
And a shift ending step in which after the synchronization of the engine rotation speed and the engagement-side input shaft speed, the controller increases the engagement-side clutch torque to terminate the shift. The method according to claim 1,
The required engine torque to be requested to be raised in the second synchronous control step is,
The target assist engine torque determined by the following equation and the target engine torque calculated by reflecting the running state of the vehicle are determined to be a large value.
Te_target_assist = min (Tc_rel, Te_target) + Je * {d (Ne-Ni_app) / dt + d (Ni_app) / dt} The method according to claim 1,
In the second synchronization control step,
Wherein the feedback control of the release side clutch torque is prohibited in a period in which the engine torque is requested to rise based on the required engine torque. The method of claim 2,
In the second synchronization control step,
Wherein the requested engine torque is requested to be lowered when the difference between the engine rotation speed and the engagement-side input shaft speed is equal to or greater than a set value in response to an increase request of the engine torque. The method of claim 4,
In the second synchronization control step,
Wherein the predetermined engine torque reduction amount is added to the previous required engine torque to reduce the required engine torque so that the required engine torque reaches the target engine torque.

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