KR100680838B1 - Shift control method continuous variable transmission on vehicle and system thereof - Google Patents

Abstract

A method and an apparatus for controlling a gearshift of continuous variable transmission are provided to prevent an engine brake due to a down-shifting by fixing a transmission ratio at a predetermined condition. A transmission ratio suitable for a current running condition is extracted from a map table when a deceleration running is detected in a coupling state of a lock up clutch, and then in a controlling state of the transmission ratio from an up-shifting to a down-shifting is performed(S104). It is determined whether or not a predetermined transmission ratio is reached during the controlling of the transmission ratio(S105). In case the predetermined transmission ratio is reached, the transmission ratio is fixed to a current state(S106). After a predetermined time, the coupling of the lock up clutch is released(S108).

Description

SHIFT CONTROL METHOD CONTINUOUS VARIABLE TRANSMISSION ON VEHICLE AND SYSTEM THEREOF}

1 is a schematic configuration diagram of a shift control apparatus of a continuously variable transmission according to the present invention.

2 is a flowchart of shift control in a continuously variable transmission according to the present invention;

3 is a timing diagram for the lockup shift control in the continuously variable transmission according to the present invention.

4 is a timing diagram for lockup shift control in a conventional continuously variable transmission.

<Explanation of symbols for the main parts of the drawings>

10: throttle detector 20: vehicle speed detector

30: brake sensor 40: control unit

50: actuator

The present invention relates to a continuously variable transmission mounted on an automobile, and more particularly, when a specific condition is reached while a shift is controlled from a high stage to a low stage by deceleration in a state where a lock up clutch is coupled, The present invention relates to a shift control method and apparatus for a continuously variable transmission in which an engine brake feeling is not generated by fixed control.

In general, the transmission which determines the appropriate reduction ratio in transmitting the output of the engine generating power to the driving wheel is divided into a manual transmission, an automatic transmission and a continuously variable transmission. The use of automatic transmissions rather than transmissions is increasing in a general trend.

In the case of automatic transmissions, the adoption of continuously variable transmissions has recently been increased due to fuel consumption deterioration caused by a large amount of power loss caused by various load factors in the apparatus.

The continuously variable transmission includes a pulley having a variable gap between the input shaft and the output shaft of the power, and is connected to a belt or chain to adjust the width of the pulley to adjust the speed ratio between the low gear and the high gear. By continuously controlling, the shift shock does not occur unlike the automatic transmission, and the driving characteristics such as the feeling of oscillation and the creep performance are almost the same as those of the automatic transmission.

The continuously variable transmission is capable of traveling at the optimum operating point of the engine, and has an excellent fuel economy of approximately 5 to 10% compared to the four-speed automatic transmission.

Such a continuously variable transmission is set with a target transmission ratio according to the opening ratio of the throttle valve, which is a driving request of the driver, and the conditions of the engine and the vehicle speed.

In the continuously variable transmission, a lock up clutch that directly connects the output of the engine is applied, and the operation of the lock up clutch is controlled to maintain the maximum operating range in order to improve fuel efficiency.

The control of the lockup clutch is set according to the shift characteristic, which is correlated with fuel economy and determines the driving characteristics of the vehicle.

As shown in FIG. 4, the conventional continuously variable transmission decelerates according to the other driving in which the lockup clutch is coupled, and thus the vehicle speed is continuously reduced as time passes based on the deceleration time. The shift ratio control is performed from the high stage (for example, the gear ratio of about 0.4) to the low stage (for example, the gear ratio of 2.5) according to the operating area set to, and releases the lockup clutch when a certain condition is reached.

However, even after the lock-up clutch is released, the state of shifting to the lower stage, that is, the gear ratio continues to be lowered, so that the same engine brake feeling as the manual transmission occurs even when a small shift is generated.

In other words, when a vehicle equipped with a manual transmission decelerates in a state in which one or two stages are combined, the engine brake feeling is very large.In the case of a continuously variable transmission, when the vehicle is decelerated at a low speed while the lockup clutch is coupled, the transmission ratio is reduced. The gear ratio similar to the standard 1st or 2nd stage of the manual transmission is formed to increase the engine brake feeling, and thus the driving characteristics are deteriorated to reduce the riding comfort. The problem arises which leads to different fuel economy reduction.

The present invention has been invented to solve the above problems, the object of which is to maintain the lock-up clutch when a certain condition set while the shift is controlled from the high end to the low end by the deceleration in the state that the lock-up clutch is engaged. In this state, the transmission ratio is fixed to a constant value so that the engine brake feeling caused by the low transmission ratio can be reduced, thereby improving the operability.

The present invention for realizing the above object is a step of controlling the speed ratio step by step from the high stage to the low stage by extracting the gear ratio corresponding to the current driving conditions from the map table when the deceleration traveling is detected in the lock-up clutch coupled state; Determining whether the speed ratio is set in the process of controlling the speed ratio from the high stage to the low stage; Determining the speed ratio fixed condition if the speed ratio is reached and fixing the speed ratio to a current state; When the predetermined time has elapsed since the transmission ratio is fixed, a shift control method of a continuously variable transmission comprising the step of releasing the engagement of the lockup clutch is provided.

In addition, the present invention includes a throttle detector for detecting a change in the opening degree of the throttle valve; A vehicle speed detector for detecting a current traveling vehicle speed from a rotation speed of the output shaft gear in the transmission; A brake sensor for detecting whether the brake pedal is operated; The map table for speed ratio control is set according to the opening ratio of the throttle valve, the state of the engine and the condition of the vehicle speed, and the specific conditions set in the process of controlling the speed ratio from high gear to low gear by coasting deceleration with the lock-up clutch engaged. A control unit for fixedly controlling the speed ratio when it arrives; According to the control of the controller provides a shift control device for a continuously variable transmission, characterized in that it comprises an actuator for controlling the hydraulic pressure supplied to the continuously variable transmission to achieve a target transmission ratio.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a shift control apparatus of a continuously variable transmission according to the present invention.

As shown, the present invention includes a throttle detector 10, a vehicle speed detector 20, a brake sensor 30, a controller 40, and an actuator 50.

The throttle detector 10 detects a change in the opening degree of a throttle valve which is opened and closed in conjunction with an accelerator pedal driven by a driver and outputs information on the opening degree of the throttle valve.

The vehicle speed detection unit 20 detects the current traveling vehicle speed from the rotation speed of the output shaft gear in the transmission and outputs information on it.

The brake sensor 30 is mounted on the brake pedal and detects whether the brake pedal is operated and outputs information on the brake pedal.

The control unit 40 sets a map table of an operating area for setting the speed ratio according to the opening rate of the throttle valve, which is a driving request of the driver, and the condition of the engine and the vehicle speed, and controls the speed ratio according to the current vehicle state. .

In addition, the control unit 40 when the shift is controlled from the high stage to the low stage due to the deceleration in the state in which the lockup clutch is coupled, when the predetermined condition is reached, the transmission ratio is fixed to a constant value in the state of maintaining the lockup clutch, and then set a predetermined schedule. If the release condition of the lockup clutch is satisfied after a lapse of time, the lockup clutch is released, and then the normal speed ratio control is performed.

The actuator 50 controls the hydraulic pressure supplied to the continuously variable transmission according to the control signal applied from the control unit 40 so as to shift to the target speed ratio.

Referring to the operation of the lock-up clutch control in the continuously variable transmission according to the present invention including the function as described above are as follows.

In the state where the lockup clutch of the continuously variable transmission is coupled and operated according to the opening ratio of the throttle valve and the condition of the engine and the vehicle speed (S101), the control unit 40 detects the current vehicle speed sound (S102) to determine whether it is being decelerated. It is determined (S103).

If it is not in the deceleration state, the process returns to the step S101. If the deceleration state is extracted, the gear ratio suitable for the current driving condition is extracted from the set map table, and then the actuator 50 is controlled in the operating area to control the speed ratio from the high stage to the low stage. (S104).

The deceleration condition is a state in which the lock-up clutch is engaged, a change in the opening degree of the throttle valve is not detected, that is, a deceleration state in the other row without driving the accelerator pedal, and a state in which the brake pedal input is not detected. .

As described above, it is determined whether the speed ratio is set to fix the speed ratio, for example, a gear ratio of 2.1 to 2.3, in the process of shifting the gear ratio from the high stage to the low stage according to the coasting deceleration coupled with the lock-up clutch (S105).

The speed ratio set for fixing the speed ratio is set under the condition of the speed ratio at which the engine brake feeling is not generated through repeated tests.

If it is not the condition of the transmission ratio set in the determination of S105, the control unit returns to the step of S104 and continuously controls the transmission ratio control from the high stage to the low stage through the control of the actuator 50, and determines the fixed condition of the transmission ratio if the condition is the set transmission ratio. By fixing the current speed ratio so that the shift to the lower stage no longer occurs (S106).

As described above, it is determined whether a predetermined time has elapsed while the deceleration driving in the state where the speed ratio is fixed is satisfied and the release condition of the lockup clutch is satisfied (S107).

If the release condition of the lockup clutch is satisfied by the elapse of a predetermined time after the transmission ratio is fixed in the determination of S107, the controller 40 releases the lockup clutch through the control of the actuator 50 and then the vehicle through the general speed ratio. Stop control of the control unit (S108).

The set time for determining the lock-up clutch release condition after fixing the speed ratio is a value extracted through repetitive testing and learning, and is an extended time such that the purpose of fuel economy is improved and the engine brake feeling is not generated.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible.

As described above, in the present invention, the lockup clutch is coupled in the continuously variable transmission and the gear ratio is fixed under a specific condition set in a state where the gear ratio is controlled from the high stage to the low stage according to the deceleration driving so that the engine brake feeling due to the low stage shift is not generated. This improves fuel economy and provides a ride comfort of the vehicle.

Claims (6)

If the deceleration traveling is detected while the lock-up clutch is engaged, extracting a gear ratio corresponding to a current driving condition from a map table and controlling the gear ratio from a high stage to a low stage in a stepwise manner; Determining whether the speed ratio is set in the process of controlling the speed ratio from the high stage to the low stage; Determining the speed ratio fixed condition if the speed ratio is reached and fixing the speed ratio to a current state; And a step of releasing the engagement of the lockup clutch when a predetermined time elapses after the transmission ratio is fixed. The method of claim 1, The shift ratio fixing condition is a value extracted through repetitive testing and learning, the shift control method of a continuously variable transmission, characterized in that it is set to an arbitrary shift ratio that does not generate a sense of engine brake. The method of claim 1, The speed ratio fixed control is a non-stop deceleration in which a lockup clutch is coupled, a change in the throttle opening degree is not detected, and the speed ratio control control is executed under the condition that the drive of the brake pedal is not detected. The method of claim 1, And after the engagement of the lockup clutch is released, a normal speed ratio control method is performed. A throttle detector for detecting a change in the opening degree of the throttle valve; A vehicle speed detector for detecting a current traveling vehicle speed from a rotation speed of the output shaft gear in the transmission; A brake sensor for detecting whether the brake pedal is operated; The map table for speed ratio control is set according to the opening ratio of the throttle valve, the state of the engine and the condition of the vehicle speed, and the specific conditions set in the process of controlling the speed ratio from high gear to low gear by coasting deceleration with the lock-up clutch engaged. A control unit for fixedly controlling the speed ratio when it arrives; And an actuator configured to control the hydraulic pressure supplied to the continuously variable transmission under the control of the controller so as to shift to a target transmission ratio. The method of claim 5, And the control unit releases the lockup clutch when the set time has elapsed after fixing the speed ratio, and then performs a general speed ratio control.

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