KR100313793B1 - Method for controlling downshift from 4 to 3-range before stopping in automatic transmission - Google Patents

Abstract

PURPOSE: A control method of downshifting from 4 to 3-range before a stop in an automatic transmission is provided to improve driving experience and durability by preventing shock with downshifting from 4 to 3-range and increasing engine output simultaneously in performing downshift before stopping by suddenly braking. CONSTITUTION: A brake switch is detected to be turned on in braking suddenly during traveling at 4-range(S100,S110). Downshift condition from 4 to 3-range before a stop is detected in turning on the brake switch(S120). Deceleration is compared with the reference value by differentiating vehicle speed with time(S130). Lowering of engine output is decided in case of the deceleration to be over the reference value, and an engine output increase signal is transmitted to an ECU(Electronic Control Unit)(S140). A duty control signal for shifting from 4 to 3-range is output to a transmission driving unit(S150). Shift quality is improved by engaging clutches sequentially with releasing kickdown servo pressure.

Description

4 → 3 downshift shifting control method before stop of automatic transmission

The present invention relates to an automatic transmission, and more particularly, 4 → 3 down before stopping of an automatic transmission for reducing shift shock generated during a shift of 4 → 3 downshift before stop by the driver's sudden brake operation during four-speed driving. It is about shift shift control method.

6 is a relationship graph between a conventional engine rpm and a hydraulic discharge amount. Reference numerals A and B of FIG. 6 illustrate shift points, and the shift points are moved from A to B in a release state caused by rapid brake and accelerator pedal operation.

In general, the shift stage of the automatic transmission vehicle, unlike the manual transmission vehicle, sets a target shift stage to shift according to a change in the opening amount of the throttle valve according to the vehicle speed and the driver's accelerator pedal operation and satisfies the shift conditions. If the shift stage is shifted to the target shift stage, the shift is completed.

Therefore, when the driver operates the sudden brake during the four-speed driving, in the conventional four to three shift control before the shift stage is stopped, the shift synchronism is checked twice to adjust the operating pressure.

However, in the above-described conventional technique, the shift control means (hereinafter referred to as TCU) according to the driver's sudden brake operation outputs a 4 → 3 downshift shift control duty control signal before stopping to release the fourth speed pressure and engage the shift stage three speeds. As shown in Fig. 6, the engine rpm is lowered as shown in Fig. 6 and the low oil pressure discharged from the oil pump as shown in Figs. 3 and 4 is formed, so that the rear clutch is instantaneously preceded by the front clutch not shown in the drawing. There was a problem that the engagement shift shock of the rear clutch occurred in the 'A' section according to the grip.

An object of the present invention is to output the engine torque increase request signal to the engine control unit (hereinafter referred to as ECU) when the shift occurs below a predetermined reference value at which the vehicle speed (No) is set by the driver's rapid brake operation during four-speed driving. The present invention provides a method of controlling a 4 → 3 downshift shift before stop of an automatic transmission for performing a 4 → 3 downshift shift before stop while increasing the output of the engine and increasing the rotational force of the oil pump.

According to an aspect of the present invention, there is provided a shift control method of an automatic transmission, the method comprising: determining whether the shift condition is a 4 to 3 downshift shift before stopping when a shift occurs due to a sudden brake operation of a driver during four-speed driving; Determining whether the vehicle deceleration amount calculated by differentiating the vehicle speed with time is greater than a set reference value if the condition is a 4 to 3 downshift shift condition before stopping according to the driver's sudden brake operation in the above step; Outputting a predetermined engine output increase request signal for increasing the engine output to the ECU if the vehicle deceleration calculated by differentiating the vehicle speed of the vehicle by the time in the above step is greater than the set reference value; Outputting a duty control signal for shifting the shift stage from the fourth speed to the third speed, which is the target shift stage, after the output of the engine is increased according to the engine output increase request signal output in the step; In this step, if the vehicle deceleration calculated by differentiating the vehicle speed with time is smaller than the set reference value, the duty control signal for shifting the shift stage from 4 speed to 3 speed, which is the target shift stage, is not outputted. Characterized in that it comprises a step of outputting.

1 is a block diagram of a 4 to 3 downshift shift control device before stop of an automatic transmission according to an exemplary embodiment of the present invention.

2 is a flowchart illustrating a method of controlling a 4 to 3 downshift shifting before stopping of an automatic transmission according to an exemplary embodiment of the present invention.

3 is a graph showing the relationship between the engine rpm and the hydraulic discharge amount according to an embodiment of the present invention.

Figure 4 is a hydraulic comparison graph according to the sudden brake operation according to an embodiment of the present invention.

FIG. 5 is a graph of hydraulic relations during a 4 to 3 downshift shift control before stopping of an automatic transmission according to an exemplary embodiment of the present invention. FIG.

6 is a relationship graph between a conventional engine rpm and a hydraulic discharge amount.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. While many specific details, such as the following description and the annexed drawings, are shown to provide a more general understanding of the invention, these specific details are illustrated for the purpose of explanation of the invention and are not meant to limit the invention thereto. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

FIG. 1 is a block diagram of a 4 to 3 downshift shift control apparatus before stopping of an automatic transmission according to an exemplary embodiment of the present invention. 2 is a flowchart illustrating a method of controlling a 4 to 3 downshift shifting before stopping of an automatic transmission according to an exemplary embodiment of the present invention. 3 is a graph showing the relationship between the engine rpm and the hydraulic discharge amount according to an embodiment of the present invention. 4 is a graph comparing hydraulic pressure according to a sudden brake operation according to an exemplary embodiment of the present invention. FIG. 5 is a graph of hydraulic relations at the time of 4 → 3 downshift shift control before stopping of an automatic transmission according to an exemplary embodiment of the present invention. FIG.

As shown in FIG. 1, the configuration of the 4 to 3 downshift shift control device before the stop of the automatic transmission according to the embodiment of the present invention is as follows.

A vehicle driving state detecting means 10 for detecting a signal that is variable and output according to a driving state of the vehicle and outputting a predetermined electric signal;

The predetermined engine output increase request signal for increasing the engine output when the engine output is reduced during the shift of 4 to 3 downshift before stopping by the driver's sudden brake operation by receiving the predetermined electric signal output from the driving state detecting means. A TCU 20 for outputting and performing a downshift of 4 → 3 before stopping;

An ECU 30 which receives an engine output increase request signal output from the TCU 20 and outputs a predetermined control signal for controlling an amount of air sucked in to increase engine output;

According to a predetermined control signal output from the TCU 20 and the ECU 30, a predetermined drive signal for increasing the output of the engine is output, and shifting is performed according to a duty control signal for shifting the shift stage to the target shift stage. It comprises a drive means 40 to perform.

In the above, the vehicle driving state detection means 10,

A throttle valve opening degree detector 11 for detecting an opening degree of a throttle valve whose opening and closing state is variable in association with an operation state of the accelerator pedal and outputting a predetermined signal;

A vehicle speed detector 12 that detects an output shaft rotational speed of the vehicle and outputs a predetermined signal corresponding to the traveling speed of the vehicle;

A shift stage detecting unit 13 for detecting a variable state of the shift stage and outputting a corresponding signal when the shift stage is changed according to the throttle valve opening amount and the vehicle speed;

A turbine shaft rotational speed sensing unit 14 for sensing a rotational speed of the turbine shaft of the torque converter connected to the input shaft of the transmission and outputting a predetermined signal;

An engine rotation speed detection unit (15) for detecting a rotation speed of the crankshaft variable according to an operating state of the engine and outputting a predetermined signal;

And a brake switch 16 which detects that the on / off state of the switch is changed and output according to the driver's brake pedal operation state and outputs a predetermined electric signal.

The following description will be given with reference to FIG. 2 of a method for controlling downshift shifting of 4 to 3 before the automatic transmission made by the above configuration.

If the driver suddenly operates the sudden brake while driving the vehicle at 4 speeds (S100), the TCU 20 determines whether the brake switch according to the sudden brake operation of the driver is turned on (S110).

When the brake switch according to the driver's sudden brake operation is turned on in step S110, the TCU 20 determines whether the 4 to 3 downshift shifting condition is satisfied before stopping (S120).

In the step (S120), if the condition is 4 to 3 downshift before the stop according to the driver's sudden brake operation, the TCU 20 determines whether the vehicle deceleration amount calculated by differentiating the vehicle speed of the vehicle with time is greater than the set reference value ( S130).

If the vehicle deceleration amount calculated by differentiating the vehicle speed of the vehicle in time (S130) is greater than the set reference value, the TCU 20 determines that the engine output is lowered and a predetermined engine output increase request signal for increasing the engine output. Is output to the ECU 30 (S140).

Therefore, the ECU 30 outputs a predetermined control signal for increasing the output of the engine to the I.S.A (Idle Speed Actuator) driver 32 according to the engine output increase request signal output from the TCU 20.

As the output of the engine increases, the TCU 20 outputs a duty control signal for shifting the shift stage from the fourth speed to the third speed, which is the target shift stage, to the shift driver 31 of the driving means 30 (S150). ).

Accordingly, the shift driver 31 releases the four-speed kick-down servo pressure according to the duty control signal output from the TCU 30, first engages the front clutch pressure, which is the three-speed actuation clutch, and sequentially engages the rear clutch.

The above embodiments are described as the most preferred embodiments, and the present invention is not limited thereto, and the embodiments can be easily described from the above embodiments.

As described above, the method of controlling the downshift shift 4 → 3 before stopping of the automatic transmission according to the present invention increases the engine power which is reduced when the driver operates the sudden brake during the fourth speed driving to perform the shift shift between shift 4 → 3 before stopping. By outputting the required signal to the ECU and increasing the engine output and performing the 4 to 3 downshift before stopping, the clutch can prevent engagement shocks, improving shifting and riding comfort and increasing the durability of the automatic transmission. It works.

Claims (2)

In the shift control method of the automatic transmission, Determining whether the shift condition is a shift of 4 to 3 downshift before stopping when a shift occurs due to a sudden brake operation of the driver during the 4-speed driving; Determining whether the vehicle deceleration amount calculated by differentiating the vehicle speed with time is greater than a set reference value if the condition is a 4 to 3 downshift shift condition before stopping according to the driver's sudden brake operation in the above step; Outputting a predetermined engine output increase request signal for increasing the engine output to the ECU if the vehicle deceleration calculated by differentiating the vehicle speed of the vehicle by the time in the above step is greater than the set reference value; Outputting a duty control signal for shifting the shift stage from the fourth speed to the third speed, which is the target shift stage, after the output of the engine is increased according to the engine output increase request signal output in the step; In this step, if the vehicle deceleration calculated by differentiating the vehicle speed with time is smaller than the set reference value, the duty control signal for shifting the shift stage from 4 speed to 3 speed, which is the target shift stage, is not outputted. 4 to 3 downshift shifting control method of the automatic transmission before the stop characterized in that it comprises a step of outputting. The method according to claim 1, further comprising outputting a predetermined control signal to the ISA driving unit for increasing the output of the engine according to the engine output increasing request signal output from the TCU. 3 Downshift shift control method.

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