KR101976950B1 - Shifting control method for continuously variable transmission - Google Patents

Abstract

The present invention relates to a technology for implementing a variable gear ratio effect while performing a shift control similar to an AT to achieve differentiated acceleration and running performance. In the present invention, when the APS answer amount is equal to or greater than a predetermined value, Determine each gear stage together with the gear stage; Determining an engine speed slope at each gear position, and correcting the engine speed slope for each gear position by reflecting a small correction factor as the gear position is higher; And the engine speed is controlled while following the corrected engine speed slope in accordance with the target gear stage when shifting from the current gear stage to the target gear stage.

Description

[0001] SHIFTING CONTROL METHOD FOR CONTINUOUSLY VARIABLE TRANSMISSION [0002]

The present invention relates to a shift control method of a CVT that can realize a variable gear ratio effect while exhibiting similar shift control to an AT, thereby achieving differentiated acceleration and running performance.

CVT (Continuously Variable Transmission) is a transmission that automatically converts the power generated by the engine into the required rotational power in accordance with the running speed and load of the vehicle to obtain the optimum torque conversion. And continuously shifts within a given shift range, unlike the automatic transmission.

As described above, the CVT can freely control the pulley ratio within a predetermined range, which is advantageous in fuel consumption and power performance, but it is evaluated that there is an NVH complaint due to excessive RPM and lack of sensation of shift events.

Recently, attention has been focused on a control system that implements a shift control similar to AT (Automatic Transmission) in a vehicle equipped with a CVT so as to add not only shift sensation but also acceleration feeling.

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 10-2015-0086453 A

SUMMARY OF THE INVENTION 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 shift control method of a CVT that can realize a variable gear ratio effect while exhibiting a speed- .

According to another aspect of the present invention, there is provided a gear shifting apparatus comprising: a gear stage determining step of determining, when a controller has an APS shift amount equal to or greater than a predetermined value, A tilt correction step of determining a tilt of the engine speed at each of the gear positions by the controller and correcting the tilt of the engine speed for each gear position by reflecting a small correction factor as the gear position is higher; And a speed control step of controlling the engine speed while following the corrected engine speed slope in accordance with the target gear stage when the controller shifts from the present gear stage to the target gear stage.

In the tilt correction step, the engine speed increase displacement is determined differently for each gear stage, and the higher the gear stage, the smaller the engine speed increase displacement.

The slope correction step may include a step of determining a slope of the road on which the vehicle is located, reflecting a smaller correction factor in the slope of the engine speed as the slope becomes larger with reference to the flat ground, And an inclination reflecting step of correcting the engine speed gradient by reflecting the factor.

The tilt correcting step determines the running mode of the vehicle and reflects a larger correction factor in the engine speed slope as the running mode approaches the sporty tendency based on the normal running mode and the running mode is close to the fuel consumption tendency And a traveling mode reflecting step of correcting the slope of the engine speed by reflecting a smaller correction factor to the engine speed slope as the vehicle speed increases.

The inclination correcting step may include an intake air temperature reflecting step of determining an intake air temperature and correcting the engine speed slope by reflecting a larger correction factor in the engine speed slope when the intake air temperature is higher when the intake air temperature is higher than a predetermined temperature .

The inclination correcting step may further include an atmospheric pressure reflecting step of determining an atmospheric pressure and correcting a slope of the engine speed by reflecting a larger correction factor in the slope of the engine speed as the atmospheric pressure becomes smaller when the atmospheric pressure is lower than a predetermined pressure have.

Wherein the tilt correction step includes a step of counting the number of consecutive upshift transmissions before the tilt correction step and counting the number of times of shifting to compensate the engine speed slope by reflecting a smaller correction factor in the engine speed slope as the number of upshifts increases, And a reflecting step.

In the step of counting the number of times of upshifting, in the step of counting the number of times of upshifting, the counted number of times of shifting may be reset at the time of downshift.

The present invention solves the above problems by implementing a variable gear ratio effect in which a gear ratio is differentiated for each gear position while performing shift control similar to that of a vehicle equipped with an AT on a vehicle equipped with a CVT, As a matter of course, it has the effect of realizing the running performance excluding the feeling of artificial AT behavior.

1 is a diagram for explaining a shift control flow in a vehicle equipped with a CVT according to the present invention;
Fig. 2 is a diagram illustrating an engine speed behavior at the time of an upshift in an oscillating situation according to the present invention; Fig.
3 is a diagram illustrating the engine speed behavior during a kick-down shift according to the present invention.
4 (a) and 4 (b) are diagrams illustrating the corrected engine speed behavior at the time of flat and gradient travel, respectively, in the present invention.
5 is a diagram exemplifying the engine speed behavior corrected for each traveling mode in 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.

The shift control method of the CVT of the present invention may be configured to include a gear step determination step, a slope correction step, and a shift step.

Referring to FIG. 1, in detail, in the gear step determination step, the controller can determine each gear step together with the current gear step based on the current gear ratio when the APS answer amount is a predetermined value or more.

For example, when there is an acceleration of the driver, if the present speed ratio according to the amount of the accelerator pedal is determined, the remaining gear stage corresponding to the current speed ratio is determined along with the current gear stage.

Table 1 below shows an example of the gear ratio determined according to the gear ratio and the gear ratio determined when the target shift is an upshift and when the gear is a downshift.

One 2 3 4 5 6 7 8 up 2.680 2.393 2.106 1.819 1.533 1.246 0.959 0.672 down 2.394 2.107 1.820 1.534 1.247 0.960 0.673 0.385

In the tilt correction step, the controller determines the slope of the engine speed at each gear position, and the higher the gear position, the smaller the correction factor is, and the slope of the engine speed can be corrected for each gear position.

Table 2 below is a correction map showing the correction factor for each gear stage. For example, the correction factor in the shift from the second stage to the third stage is set smaller than the correction factor in the shift from the first stage to the second stage.

One 2 3 4 5 6 7 8 Correction factor 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0

In the speed control step, when the controller shifts from the present gear position to the target gear position, the engine speed can be controlled while following the corrected engine speed gradient in accordance with the target gear position.

That is, by correcting the engine speed slope by reflecting the correction factor set in accordance with the target gear stage, the slope of the engine speed gradually becomes smaller as the shift from the lower end to the higher end is made. On the contrary, as the shift from the higher end to the lower end is performed, The tilt is getting smaller.

For example, FIG. 2 illustrates the engine speed behavior at the time of the upshift in the vehicle oscillation state. The slope of the engine speed when the upshift is performed from the first stage to the second stage is changed from the second stage to the third stage Is formed so as to be steeper than the engine speed gradient at the time of shifting.

3 shows an example of the engine speed behavior during a kick down shift. When the downshift is performed from the sixth stage to the fifth stage, when the engine speed gradient is from the fifth stage to the fourth stage, Is formed more gently than the engine speed gradient.

Therefore, while realizing the AT-level gear ratio effect, the effect of varying the gear ratio for each gear stage at the time of shifting can be realized, and the acceleration feeling and the driving performance differentiated from each other can be exhibited.

Further, in the tilt correcting step, the engine speed increase displacement is determined differently for each gear stage, and the engine speed increase displacement is controlled to be greater for the lower stage.

That is, as shown in FIG. 2, it is possible to control the engine speed so that the ratio between the first stage and the second stage becomes greater than the stage ratio between the second stage and the third stage. As shown in FIG. 3, The engine speed can be controlled so as to be larger than the inter-stage ratio of the gear ratio, and the gear ratio variable effect can be realized more reliably for each gear stage.

In addition, the tilt correction step of the present invention determines the inclination of the road on which the vehicle is located, and reflects a smaller correction factor in the engine speed gradient as the inclination degree increases with respect to the flat ground. As the inclination degree decreases, And an inclination reflecting step of correcting the engine speed gradient by reflecting a larger correction factor to the inclination.

Table 3 below is a correction map illustrating the correction factor by the degree of inclination.

-15 -10 -5 0 5 10 15 20 Correction factor 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6

For example, FIGS. 4 (a) and 4 (b) show the engine speed behavior at the time of flat running and grading, respectively, and the slope of the engine speed at a gradient is more gradual than that of the flat running.

That is, as the ascending slope becomes larger, the slope of the engine speed becomes gradually gentle, and as the slope becomes lower, the slope of the engine speed becomes smaller.

The inclination correcting step of the present invention determines the running mode of the vehicle and reflects a larger correction factor in the engine speed slope as the running mode approaches the sporty tendency based on the general running mode, And a traveling mode reflecting step of reflecting a smaller correction factor in the engine speed slope to correct the engine speed slope as the fuel slope approaches the fuel consumption tendency.

Table 4 below is a correction map exemplifying the correction factor for each traveling mode.

Eco mode Normal mode Sports mode Correction factor 0.8 1.0 1.2

For example, FIG. 5 shows a comparison of engine rotational speed behaviors according to the traveling mode, wherein the slope of the engine rotational speed in the sport mode is more paralle with respect to the normal mode, while the slant of the engine rotational speed in the eco mode is slower It becomes.

In the tilt correction step of the present invention, the intake air temperature is determined. When the intake air temperature is higher than a predetermined temperature, the intake air temperature is corrected to reflect a larger correction factor in the engine speed gradient, Reflection step.

Table 5 below is a correction map exemplifying a correction factor for each intake temperature.

0 20 30 40 50 60 70 80 Correction factor 1.0 1.0 1.0 1.0 1.1 1.2 1.3 1.4

The inclination correction step may further include an atmospheric pressure reflection step of determining an atmospheric pressure and correcting the engine speed slope by reflecting a larger correction factor in the engine speed slope as the atmospheric pressure is decreased as the atmospheric pressure is less than a predetermined pressure .

Table 6 below is a correction map illustrating the correction factor by atmospheric pressure.

0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 Correction factor 1.1 1.1 1.1 1.1 1.0 1.0 1.0 1.0

In other words, the acceleration feeling can be compensated by correcting the slope of the engine speed upward when the engine is running at a high intake air temperature and a high altitude.

The tilt correction step may include counting the number of consecutive upshift transmissions before the tilt correction step and correcting the engine speed slope by reflecting a smaller correction factor in the engine speed slope as the number of upshifts increases And may further include a shift count reflecting step.

Table 7 below is a correction map exemplifying the correction factor for each upshift continuous shift speed.

One 2 3 4 5 6 7 8 Correction factor 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2

That is, during the linear acceleration, as the number of times of upshifting increases, the slope of the engine speed is corrected by relatively lowering the slope of the engine speed, and the slope of the engine speed gradually becomes smaller as the shift from the lower end to the higher end is performed.

However, in a case where a downshift shift occurs due to an event such as kick down shift in the counting of the upshift number of times, the counted number of shifts can be reset.

Referring to FIG. 1, a shift control flow of the CVT according to the present invention will be sequentially described. When a kick down shift is performed by the driver depressing an accelerator pedal (S10) Determines the gear ratio, and determines the remaining gear stage together with the current gear stage corresponding to the speed ratio.

Then, as the gear stage is higher for each gear stage, the slope of the engine speed is corrected by reflecting a small correction factor (S20).

When shifting from the present gear position to the target gear position, the engine speed is controlled to be increased while following the corrected engine speed slope in accordance with the target gear position (S30)

At the same time, in the process of controlling the engine speed while following the corrected engine speed slope, it is determined whether there is a change in the gradient of the road on which the vehicle is located (S40). If there is a gradient change, The engine speed gradient is corrected (S50).

Further, the engine speed slope is corrected using a correction factor set in accordance with the intake air temperature and the atmospheric pressure (S60).

Then, it is determined whether there is a change in the traveling mode of the vehicle (S70). If there is a change in the traveling mode, the slope of the engine speed is corrected through the correction factor set in accordance with the traveling mode (S80).

Thereafter, when the upshift or kick down shift occurs again (S90), the control goes back to step S20 to perform the control. When the upshift or kick down shift does not occur, the APS answer amount is less than the predetermined value As in the case, when the predetermined release condition is satisfied, the normal traveling mode is returned.

As described above, the present invention realizes a variable gear ratio effect in which the gear ratio is differentiated for each gear position while performing shift control similar to that of a vehicle equipped with an AT on a vehicle equipped with a CVT, Thereby realizing the driving performance excluding the feeling of artificial AT behavior.

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, .

Claims (8)

A gear stage determining step of determining each gear stage together with a current gear stage based on a current gear ratio when the controller has an APS input amount equal to or greater than a predetermined value;
A tilt correction step of determining a tilt of the engine speed at each of the gear positions by the controller and correcting the tilt of the engine speed for each gear position by reflecting a small correction factor as the gear position is higher; And
And a rotation speed control step of controlling the engine speed while following the corrected engine speed slope in accordance with the target gear stage when the controller shifts from the current gear stage to the target gear stage,
The tilt correction step may include:
Shift count reflecting step of counting the number of consecutive upshift transmissions before the inclination correcting step and correcting the engine speed slope by reflecting a smaller correction factor in the engine speed slope as the number of upshifts increases Wherein the CVT is controlled by the control unit. The method according to claim 1,
In the tilt correction step,
Wherein the engine revolution speed increase displacement is determined differently for each gear stage, and the engine revolution speed increase displacement is smaller the higher the gear stage. The method according to claim 1,
The tilt correction step may include:
The inclination of the road on which the vehicle is located is determined to reflect a smaller correction factor in the slope of the engine speed as the slope becomes larger on the basis of the flat surface and a larger correction factor is reflected in the slope of the engine speed as the slope becomes smaller, And a tilt reflection step of correcting the tilt of the vehicle. The method according to claim 1,
The tilt correction step may include:
A larger correction factor is reflected in the slope of the engine speed as the running mode approaches the sporty slope on the basis of the normal running mode, and as the running mode approaches the fuel efficiency slope, the slope of the engine speed slope Further comprising a traveling mode reflecting step of reflecting a smaller correction factor to correct the engine speed slope. The method according to claim 1,
The tilt correction step may include:
And an intake air temperature reflecting step of determining an intake air temperature and correcting the engine speed slope by reflecting a larger correction factor in the engine speed slope as the intake air temperature increases when the intake air temperature is higher than a predetermined temperature Variable speed control method of CVT. The method according to claim 1,
The tilt correction step may include:
And an atmospheric pressure reflecting step of determining the atmospheric pressure and correcting the engine speed slope by reflecting a larger correction factor in the engine speed slope as the atmospheric pressure becomes smaller when the atmospheric pressure is lower than a predetermined pressure Control method. delete The method according to claim 1,
Wherein the step of counting the number of times of shifting in the downshift in the step of counting the number of times of upshifting is reset in the step of counting the number of times of shifting.

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