KR100279444B1 - Creep Shift Control Method of Automatic Transmission - Google Patents

Abstract

The present invention relates to a creep shift control method of an automatic transmission. When an accelerator pedal is turned on during a creep, the present invention provides a sufficient hydraulic pressure to hold a creep control duty for a set time to perform reaction force control of a kickdown band. With the value Da as the initial value and the al as the duty gradient, the duty control is carried out until the hydraulic speed of the kickdown band is drastically reduced while the rotational speed Nt of the turbine shows a difference between the set reference values. When the difference between the reference values is set, the duty is adjusted by dD to decrease the calculated duty value as the initial value, and the a2 is the duty slope to gradually reduce the reaction side hydraulic pressure while kicking to the first speed determination point (SF1). The release control of the down drum is carried out, and in order to absorb the determination error from the first speed synchronization decision point SF1, When the speed reaches the synchronous completion determination point (SF2) at which the gear stage reaches the target gear stage without changing the value, the shift signal is switched to 1 speed and the duty control signal is output 100% to zoom. When shifting to the 1st speed when the accelerator pedal is on in the creep state, the creep 1st speed control is performed to reduce the shift short at the time of shifting, and by applying the 2nd speed creep control, it is possible to prevent the back of the slope.

Description

Creep Shift Control Method of Automatic Transmission

The present invention relates to a creep shift control method of an automatic transmission, and more particularly, to shift the creep during the creep when the accelerator pedal is turned on at a speed of 2 speed creep, to prevent the occurrence of a shift shock. It relates to a control method.

In general, the control of the creep area in the automatic transmission is performed when the shift lever is stopped in the D or 2 range, that is, in order to obtain an appropriate creep area in the idle state. It supplies hydraulic pressure to (Kick Down Brake) to control the transmission gear at 2 speeds, and controls the hydraulic pressure applied to the kick down servo to be lower than the normal 2 speed driving.

As described above, the shift control device appropriately adjusts the hydraulic pressure acting on the kickdown servo to obtain a low creep force.

Therefore, the creep state is divided into two speeds (69%) creep and one speed (85%) creep according to the hydraulic control duty.

In the past, second-speed creep was applied, but now, first-speed creep is applied.

The reason for the above is that when shifting from the second-speed creep to the first speed when the accelerator pedal is on, the vehicle shifts to only one-way clutch (O.W, C: One Way Clutch) without the control of the kick-down band, which causes a large shock.

However, the above-described conventional technique has a problem in that the reaction force is pushed backward in the gradient road because the reaction force side is a one-way clutch, unlike in the second speed creep.

Accordingly, an object of the present invention is to provide a creep shift control method of an automatic transmission capable of reducing the shift short and preventing the back from being shifted in a gradient path by performing creep 1 speed control when the accelerator pedal is on in the 2-speed creep state while driving. will be.

In order to achieve the above object, the present invention determines whether creep control is performed in a state in which a vehicle is running, and if creep control is driven, it is determined whether an accelerator pedal is turned on, and a set reference time is elapsed by outputting a creep duter at 0%. Determining whether it has been done; Setting an initial duty in the creep control map and outputting a duty control signal when the set reference time elapses; According to the duty control signal output from the above, it is determined whether the difference in the reference value is set from the rotation speed of the turbine in the second speed creep state, and the rotation speed of the turbine is set from the rotation speed of the turbine in the second speed creep state. Outputting a duty control signal with a new duty value and a duty gradient after obtaining a difference of? Determining whether first speed synchronization is performed according to the duty control signal, and determining whether first synchronization detection has been completed; When the duty control signal output from the above is synchronized, the shift signal is switched to 1 speed and the duty control signal is output to 100%.

1 is a block diagram of a creep shift control apparatus of an automatic transmission according to the present invention.

2 is a flowchart illustrating a creep shift control method of an automatic transmission according to the present invention.

3 is a creep shift control duty pattern diagram of an automatic transmission according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention, which can be achieved and realized in detail by the above objects, will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, a configuration of a creep shift control apparatus of an automatic transmission according to an exemplary embodiment of the present invention is a vehicle driving state in which a signal that is varied and output according to a driving state of an automatic transmission is applied and outputs a corresponding signal. Sensing means 10; The vehicle outputs a duty control signal for controlling the reaction side kick-down band when shifting from the second speed creep to the first speed creep state by shifting the creep to the second speed state without receiving the signal output from the vehicle driving state detecting means 10. And control means 20 and; The driving means 30 is configured to receive a signal output from the shift control means 20 to shift the shift stage to the target shift stage.

The vehicle driving state detecting means 10 includes: a throttle valve opening degree detecting unit 11 for detecting an opening degree of a throttle valve whose opening and closing state is variable in association with an operation state of an accelerator pedal and outputting a corresponding signal; An output shaft rotation speed detection unit 12 for outputting different values according to the state of engagement of the vehicle automatic transmission shift stage and detecting an output shaft rotation speed corresponding to the vehicle speed; A shift stage sensing unit 13 configured to detect a variable state of the shift stage and output a corresponding signal when the shift stage is changed according to the throttle valve opening amount and the vehicle speed; An engine rotation speed detection unit 14 for detecting a rotation speed of the crankshaft which is varied according to an operating state of the engine and outputting a corresponding signal; Turbine shaft rotation speed detection unit 15 for detecting the rotational speed of the turbine shaft of the torque converter connected to the input shaft of the transmission and outputs a corresponding signal.

The present invention configured as described above determines whether the control means 20 is currently creep control in the state that the vehicle is running (S100).

When the driving state of the vehicle is under creep control, the control means 20 determines whether the accelerator pedal is in the on state (S110).

When the accelerator pedal is in the above state, the control means 20 outputs a creep duty at 0% as shown in the attached section a of FIG. 3, and drives its own timer to be a predetermined reference time t1. It is determined whether the duty retention time (XTC11 = 100ms) has elapsed (S120, S130).

That is, during the duty retention time (XTC11 = 100ms), which is a predetermined reference time, the creep duty control signal is delayed to 0% to supply sufficient hydraulic pressure to perform the reaction force control of the kickdown band.

Therefore, when the duty retention time (XTC11 = 100ms), which is a predetermined reference time, has elapsed, the control means 20 is initially initialized in the creep control map stored in the memory, as shown in the section b of FIG. The duty Da is output and the duty gradient is set to a1 to output the duty control signal DH, thereby rapidly reducing the oil pressure of the kickdown band by the duty initial value and the slope outputted above (S140 and S150).

The duty control signal DH = Da + a1

Where Da is the set initial duty value and a1 is the set duty slope.

As the hydraulic pressure of the kickdown band is drastically reduced by the duty control signal set as described above, the control means 20 arbitrarily selects the rotation speed Nt of the turbine at the speed Nt of the turbine in the second speed creep state. It is determined whether there is a difference in the turbine rotation speed (XNTC1 = 35 RPM) which is the set reference value (S160).

In the above, when a difference in the turbine rotation speed (XNTC1 = 35 RPM), which is a predetermined reference value set from the rotation speed of the turbine in the second speed creep state, occurs, the control means 20 is attached. As shown in section C of 3, the duty value is set at the duty value DH outputted at step S150 from the point of time when the turbine speed Nt represents the difference between the turbine speed XNTC1 = 35 RPM, which is the set reference value. Release the kick-down drum to the 1st speed determination point (SF1) while reducing the reaction side hydraulic pressure by outputting the duty control signal (D1) with the new duty value (D) and the duty gradient (a2) after decreasing by the correction value dD. Control is performed (S170, S180).

D = DH-dD

(Here, D is the initial output duty value after duty value correction, DH is the output duty value before duty value correction, and dD is the set correction duty value.)

D1 = D + a2

(Here, D1 is a duty control signal output value after duty value correction, D is an initial duty value calculated after duty value correction, and a2 is a set duty slope.)

However, in the above case, when the turbine speed Nt is not different from the turbine speed XNTC1 = 35 RPM, which is a predetermined reference value, from the rotation speed Nt of the turbine in the second speed creep state, the control means 20. The driving means (DH) is driven until the difference in the turbine speed (XNTC1 = 35 RPM), which is a set reference value, occurs from the rotation speed (Nt) of the turbine in the second speed creep state. Output to 30).

As the duty control signal D1 is output and the release control of the kickdown drum is performed, the control unit 20 determines whether the first speed synchronization determination point SF1 has been detected (S190).

When the first speed synchronization decision point SF1 is detected, the control means 20 arbitrarily selects the first synchronization decision point after the first synchronization decision point in order to absorb an error occurring in the synchronization point determination, as shown in section d of FIG. The duty value D1 outputted above is continuously output to the driving means 30 for the duty holding time (XTC12 = 100ms), which is a predetermined time, and it is determined whether the shift stage reaches the synchronization completion determination point SF2 which is the target shift stage. (S200).

However, if the primary synchronization determination point SF1 is not detected in the above, the control means 20 continues to output the duty control signal D1 until the primary synchronization determination point SF1 is detected.

When the shift stage reaches the synchronization completion determination point SF2 which is the target shift stage, the control means 20 switches the shift signal to 1 speed as shown in section e of FIG. The signal is output to the driving means 30 by 100% (S210).

However, when the shift stage does not reach the synchronization completion determination point SF2 which is the target shift stage, the control means 20 drives the corresponding duty control signal until the shift stage reaches the target shift stage. Continue to print on

As described above, according to the present invention, the accelerator pedal is turned on during the creep, and the creep control duty is arbitrarily maintained for a predetermined time to supply sufficient hydraulic pressure to perform the reaction force control of the kickdown band. While reducing the hydraulic pressure of the turbine, the duty control is performed until the turbine speed (Nt) shows the difference of 35 RPM, which is the set reference value. After correcting by dD and decreasing, the kick-down drum is released to the 1st speed synchronization point SF1 while gradually reducing the reaction-side hydraulic pressure by the duty gradient, and the duty value is maintained for 100 ms, which is the time set after the 1st speed synchronization point. When the speed reaches the synchronous completion determination point (SF2) at which the speed is reached at the target speed, the shift signal is switched to 1 speed. By giving to the control signal output of 100%, it is to reduce a shift shock when the shift into the turns on the accelerator pedal 1 in the second speed state creep would be to provide an effect capable of preventing the advance backward in a gradient.

Claims (3)

Determining whether creep control is being performed while the vehicle is running; Determining whether the accelerator pedal is on when the creep control is performed; Outputting a creep duty at 0% when the accelerator pedal is turned on during the creep control and determining whether a predetermined reference time has elapsed; Setting an initial duty Da in the creep control map when the preset reference time elapses, and setting the initial duty Da to a1 as a duty gradient to output a duty control signal DH; Determining whether a difference in a reference value set from the rotation speed Nt of the turbine at the second speed creep state occurs when the duty control signal DH is output; In the case where the rotation speed Nt of the turbine is different from the preset reference value, the duty value is decreased by the duty correction value dD after the turbine speed Nt represents the difference of the set reference value, and then the new duty value ( D) and outputting a duty control signal D1 at a duty gradient a2; Determining whether a first speed synchronization determination point (SF1) has been detected when the duty control signal (D1) is outputted; When the first speed synchronization determination point SF1 is detected, the synchronization completion determination point SF2 at which the shift stage reaches the target shift stage by continuously outputting the duty value D1 outputted in the step for a set time after the first synchronization determination point SF1. Determining whether it is reached; And shifting the shift signal to 1 speed to output a 100% duty control signal when the duty control signal outputted in the above is synchronized. 2. The method of claim 1, further comprising: continuously outputting the duty control signal D1 until the first speed synchronization decision point SF1 is detected. Creep shift control method of automatic transmission. The turbine speed Nt of the turbine according to claim 1, wherein when the reference value difference does not occur from the rotation speed Nt of the turbine in the second speed creep state, the turbine speed Nt of the turbine is in the second speed creep state. A creep-shift control method for an automatic transmission, comprising continuously outputting the duty control signal DH until a reference value difference occurs from the turbine speed Nt.