KR100262574B1 - 4-3down shift control method for a/t - Google Patents

Abstract

PURPOSE: A control method for a 4-3 down shift of an automatic transmission is provided to prevent a tie-up by making a fourth speed keeping time long during a power-off and to conduct a skip shift by independently controlling a rear clutch. CONSTITUTION: To control the 4-3 down shift of an automatic transmission, a control system senses an engine rpm(revolutions per minute) to change speed from the fourth speed to the third speed and senses the opening degree of a throttle valve. After that, the control system decides if a driven state is in a power-on state or a power-off state. In case of the power-on state, first and second solenoid valves are turned off to release the hydraulic pressure of a fourth speed pipe line and third and a fourth solenoid valves are controlled with an initial duty rate. The duty rate is changed according to the change rate of a turbine rpm after the set time of the third and the fourth solenoid valve passes by. After that, a corresponding frictional factor is operated and released to complete a synchronism and the 4-3 down shift is completed.

Description

4-3 Downshift Shift Control Method for Automotive Automatic Transmission

FIG. 1 is a view showing a hardware configuration of a shift control unit of a hydraulic control apparatus according to the present invention. FIG.

FIG. 2 is a hydraulic circuit diagram of a hydraulic control apparatus according to the present invention, which is a hydraulic circuit diagram showing a process of downshifting from fourth speed to third speed at power-on.

3 is a flowchart for explaining a shift control operation of the hydraulic control apparatus according to the present invention;

FIG. 4 is a graph showing changes in turbine speed according to time when downshifting from fourth speed to third speed at power-on.

5A and 5B are graphs showing ON / OFF states of the first and second solenoid valves for controlling the shift control valve at power-on in the shift control method according to the present invention.

6A and 6B are graphs showing the duty ratios of the third and fourth solenoid valves for controlling the pressure control valve at power-on in the shift control method according to the present invention.

Figure 7 is a hydraulic diagram of power-on.

Fig. 8 is a hydraulic circuit diagram showing a hydraulic control system of a hydraulic control apparatus according to the present invention. Fig. 8 is a hydraulic circuit diagram showing an initial process of downshifting from fourth speed to third speed at power-off.

FIG. 9 is a graph showing changes in turbine speed with time when downshifting from fourth speed to third speed at power-off time; FIG.

10A and 10B are graphs showing ON / OFF states of the first and second solenoid valves for controlling the shift control valve at power-off in the shift control method according to the present invention.

11A and 11B are graphs showing the duty ratios of the third and fourth solenoid valves for controlling the pressure control valve at power-off in the shift control method according to the present invention.

Figure 12 is a hydraulic diagram of power off.

13 is a view for explaining a process in which the conventional hydraulic control apparatus is downshifted from the fourth speed to the third speed.

[0001] The present invention relates to a shift control method for an automatic transmission for a vehicle, and more particularly, to a shift control method for a vehicle automatic transmission that can be controlled in accordance with power on and power off when downshifting from 4 to 3 speeds, To the third speed, the fourth-speed holding time is extended to enable the tie-up control.

The automatic transmission includes a torque converter and a multi-stage transmission mechanism connected to the torque converter. The automatic transmission includes a hydraulic operation friction element for selecting one of the gear stages of the transmission mechanism according to the running state of the vehicle .

The hydraulic control system of the vehicular automatic transmission has a function of selecting the friction element through the control valve and operating the hydraulic pressure generated from the oil pump.

The hydraulic control system includes a pressure regulating means for regulating the hydraulic pressure generated from the oil pump, a manual and automatic speed change control means capable of forming a speed change mode, A hydraulic control means, a damper clutch control means for a damper clutch operation of the torque converter, and a hydraulic pressure distributing means for distributing an appropriate hydraulic pressure supply to each friction element.

The hydraulic control means controls the supply line pressure acting on the friction element, the torque converter supply pressure, the solenoid valve supply pressure, and the like, which substantially affects the transmission feeling.

To facilitate the understanding of the present invention, the process of downshifting from the fourth speed to the third speed in the conventional hydraulic control apparatus will be described with reference to FIG.

A torque converter 100 that receives power from an engine and transmits the torque to the transmission side, and an oil pump 102 that generates and discharges oil necessary for the torque converter and gear range control.

A pressure regulating valve 106 which is generated from the oil pump 102 and which regulates the hydraulic pressure flowing along the conduit 104 to a constant pressure, a torque converter control valve (regulator) 106 for regulating the pressure of the torque converter and the lubricating oil 108), and a damper clutch control valve (110) for increasing the power transmission efficiency of the torque converter.

A part of the oil generated from the oil pump 102 is supplied to a reducing valve 112 for maintaining a lower pressure than the line pressure at all times and a manual switch for switching the oil passage while operating in conjunction with the position of the selector lever in the driver's seat And constitutes a flow path that can be supplied to the valve 114.

The constant hydraulic pressure reduced by the reducing valve 14 constitutes a flow path that can be used as a control pressure of a high-low pressure valve (not shown) that lowers the line pressure at the high-speed end and minimizes the drive loss of the oil pump And a part of the hydraulic pressure is supplied to the pressure control valve 116 to constitute a flow path which can be used as the control pressure.

And a part of the hydraulic pressure supplied to the pressure control valve 116 is used to make a controllable pressure of the N-R control valve 118 which reduces the shift shock when the mode is changed from the neutral range to the reverse range.

The first solenoid valve S1 and the second solenoid valve S1 which are ON / OFF-controlled by the transmission control unit TCU are connected to the pipeline 120 through which hydraulic pressure flows when the manual valve 114 is in the running (D) And the shift control valve 122 for switching the oil passage by the action of the oil pressure switch S2 is communicated with the hydraulic pressure supply device.

The pipeline 120 is connected to the first conduit 124 to supply the hydraulic pressure to the pressure control valve 116. The shift control valve 122 is connected to the second conduit 126, Speed line 128 and a fourth-speed line 130 are connected to each other to supply the control hydraulic pressure to the plurality of shift valves for controlling the respective speed change stages.

The second-speed line 126 is supplied to the left end port of the 1-2 shift valve 132 to control the valve, and the third-speed line 128 is connected to the 2-3 / 4-3 shift valve And the fourth speed line 130 is supplied to the left end port of the end clutch valve 136 and the rear clutch release valve 138 so as to control the respective valves .

Meanwhile, the pressure control valve 116 is configured so that the third solenoid valve S3 can switch the flow path. The damper clutch control valve 110 is connected to the fourth solenoid valve S4 via the fourth solenoid valve S4, Can be switched.

The hydraulic pressure supplied to the pressure control valve 116 is controlled by the third solenoid valve S3 so that the ND control valve 122 reduces the shift shock when the selector lever is selected as the driving range (D) And a hydraulic pressure can be supplied to the rear clutch C 1, which is the first friction element, through the oil passage 140.

The rear clutch release valve 138 is provided in the oil passage connecting the ND control valve 140 and the rear clutch C1 so that the oil pressure can be supplied to the rear clutch or the supplied oil pressure can be discharged .

The oil pressure is supplied from the pressure control valve 116 to the kickdown servo C2, which is the second friction element acting as a reaction element at the second speed via the 1-2 shift valve 132.

Part of the oil pressure passing through the 1-2 shift valve 132 passes through the 2-3 / 4-3 shift valve 134 and is transmitted through the front clutch C3, which is the third friction element acting as the third speed input element And the hydraulic pressure of a part of the oil pressure controls the end clutch valve 136 so that the hydraulic pressure flowing to the third-speed channel 128 becomes the fourth friction And constitutes a flow path that can be supplied to the end clutch C4.

When the manual valve 114 is in the reverse range, the hydraulic pressure supplied to the reverse first control line 142 is transmitted through the 1-2 shift valve 36 to the fifth friction element C5 And the second backward control line 144 is connected to the manual valve 114 in order to operate the third friction element C3 acting as an input element.

The second friction element C2 is provided with a kick-down switch 146 in the operating chamber to be turned off when the hydraulic pressure is supplied to the operating chamber h1 and to be turned on when supplied to the releasing chamber h2. So that the signal can be transmitted to the electronic control unit (TCU).

The hydraulic control apparatus includes three clutch means for transmitting rotational power by hydraulic pressure control, two brake means, and a shift planetary gear train having a complex planetary gear device employing a one-way clutch structurally rotatable only in one direction It is possible to perform the step control.

However, since a known power train can be used, a description of the configuration of the power train will be omitted. However, what clutch means or brake means acts at each gear stage will be described.

The rear clutch C1 is operated by the rear clutch C1 and the hydraulic pressure is controlled and the rotation in the opposite direction to that in which the one-way clutch is engaged is restrained in the running (D) range 1. In the second speed, The rear clutch C1, the front clutch C3 and the end clutch C4 both act as input elements in the third speed and the kickback servo (third speed) C2) acts to realize the speed change stage control.

When the downshift is made to the third speed in the fourth speed range of the running (D) range, the conventional hydraulic control device thus configured is operated by the operating pressure of the front clutch C3 The downshift servo C2 is released, and the hydraulic oil pressure is supplied to the rear clutch C1 to complete the third speed synchronization.

However, in the 4-3 downshift control of this method, the end clutch C4, which was operating in the fourth speed, must be kept operating without changing the pressure. Since the control pressure is supplied by the pressure control valve, And a pressure drop occurs temporarily in the process of changing the shift valve that supplies the hydraulic pressure to the end clutch, so that a shift shock is generated.

In addition, since the control is performed without distinguishing between the power-on state and the power-off state, there is a limitation in increasing the driving power at the time of power-off, and the tie-up phenomenon of the transmission occurs due to the shortened fourth-

Further, since the rear clutch is indirectly controlled, there is a disadvantage that the skip transmission is impossible.

SUMMARY OF THE INVENTION The present invention has been made in order to overcome the problems of the prior art as described above, and it is an object of the present invention to provide a control system for a vehicle, The present invention is to provide a shift control method in which a tie-up phenomenon can be prevented by lengthening the holding time, and the rear clutch can be independently controlled to perform skip-shift.

In order to realize the object of the present invention as described above, port conversion is performed by solenoid valves which are controlled on and off by a transmission control unit, and port conversion of shift valves for supplying or interrupting hydraulic pressure to each friction element is performed A shift control method of a vehicular automatic transmission in which a control pressure is supplied to each friction element by duty control of another solenoid valves at a shift timing,

Sensing the number of revolutions of the engine in order to perform the shifting to the third speed when the fourth speed decelerates while the vehicle is running;

Sensing an opening rate of the throttle valve,

Determining whether the driven state is a power on state or an off state after the above steps;

Turning off the first and second solenoid valves for controlling the port switching of the shift control valve to release the oil pressure of the fourth speed line when the power ON state is determined in the step,

And changing the duty ratio of the third and fourth solenoid valves for performing the port conversion of the first and second pressure control valves in accordance with the rate of change of the turbine rpm according to the lapse of the set time at the power-on, Shift downshift control method.

The step of releasing the oil pressure of the fourth speed line by turning off the first and second solenoid valves for controlling the port conversion of the shift control valve when the determination value is determined to be power off in the step of determining the driven condition,

And changing the duty ratios of the third and fourth solenoid valves for performing the port conversion of the first and second pressure control valves in accordance with the rate of change of the turbine rpm with the lapse of the set time at the time of power- -3 downshift speed change control method.

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

FIG. 1 is a block diagram showing a control unit hardware according to the present invention. An input coil of a transmission control unit (TCU) is connected to an ignition coil Ic for detecting the number of revolutions of the engine. This ignition coil outputs two pulses per rotation to calculate the number of revolutions of the engine.

In addition, a throttle position sensor (TPS) is connected to another input terminal to sense the opening ratio of the throttle valve, and a pulse generator (Pg) is connected to another input terminal for sensing the rotation speed of the output shaft.

The other input of the transmission control unit (TCU) is connected to a switch Ps for detecting power on / off.

The first solenoid valve S1 and the second solenoid valve S2 are electrically connected to the output terminal of the transmission control unit TCU to control the port switching of the shift control valve. A third solenoid valve S3 and a fourth solenoid valve S4 for controlling the port conversion are connected.

FIG. 2 shows a hydraulic control system according to the present invention in which the downshifting from the fourth speed to the third speed is performed at power-on. Before shifting to the third speed, the kick-down servo C2 and the end clutch (C4) is in operation.

The electronic control hydraulic control system is a system in which the solenoid valves, which are on / off-controlled or duty-controlled by a transmission control unit (TCU) receiving a throttle valve opening signal and a vehicle speed signal, .

However, the hydraulic control system includes a torque converter 2 that receives power from an engine and transmits torque to the transmission, and an oil pump 4 that generates and discharges oil necessary for the torque converter and gear range control ).

A pressure regulating valve 8 which is generated from the oil pump 4 and makes the pressure of the oil flowing along the duct 6 constant, a torque converter control valve 10 which constantly regulates the pressure of the torque converter and the lubricating oil ), And a dam-clutch control valve 12 for increasing the power transmission efficiency of the torque converter.

A part of the oil generated from the oil pump 4 is supplied to a reduction valve 14 for maintaining a lower pressure than the line pressure at all times and a manual operation for switching the oil passage while operating in conjunction with the position of the selector lever in the driver's seat And constitutes a flow path which can be supplied to the valve 16.

The constant hydraulic pressure reduced by the reducing valve 14 constitutes a flow path that can be used as the control pressure of the high-low pressure valve 18 which lowers the line pressure at the high-speed end and minimizes the drive loss of the oil pump And a part of the oil pressure is supplied to the first pressure control valve 20 and the second pressure control valve 22 to constitute a flow path which can be used as the control pressure.

A part of the hydraulic pressure supplied to the twelfth pressure control valve makes a flow path that can be used for the control pressure of the N-R large trolley valve 24 which reduces the shift shock when the mode is changed from the neutral range to the reverse range.

The first solenoid valve S1 and the second solenoid valve S2 which are on / off controlled by the transmission control unit are connected to the line 26 through which the hydraulic pressure flows when the manual valve 16 is in the running (D) So that the shift control valve 28 for switching the oil passage is communicated to be supplied with the hydraulic pressure.

The second shift control valve 28 is connected to the second speed line 30, the third speed line 32 and the fourth speed line 34 to supply the control hydraulic pressure to the plurality of shift valves for controlling the respective speed change stages .

That is, the second-speed conduit 30 is supplied to the left end port of the 1-2 shift valve 36 to control the valve, and the third-speed conduit 32 is connected to the 2-3 / 4-3 shift valve And the fourth-speed line 34 is connected to the right-hand end port of the 2-3 / 4-3 shift valve 38 and the 2-4 / 3- 4 shift valve 40 and the left end port of the end clutch valve 42 so as to control each valve.

Meanwhile, the first pressure control valve 20 is configured so that the third solenoid valve S3 can switch the flow path, and the second pressure control valve 22 is configured to be switched by the fourth solenoid valve S4 So that the flow path can be switched.

The first passage 44 is branched to the pipeline 26 connected to the manual valve 16 and supplied to the first pressure control valve 20 and the second pressure control valve 22 so that the third and fourth solenoid valves S3 and S4 via the 2-4 / 3-4 shift valve 40 to the first friction element C1, which is the first-speed input element.

The first pressure control valve 20 constitutes a flow path through which the hydraulic pressure can be supplied to the second friction element C2 acting as a reaction force element at the second speed via the 1-2 shift valve 36.

Further, a part of the hydraulic pressure via the 1-2 shift valve 36 passes through the 2-3 / 4-3 shift valve 38 and is transmitted via the end clutch valve 42 to the end And the hydraulic pressure supplied to the end crusher C4 is configured to be supplied to the port 46 of the accumulator 43. The hydraulic pressure supplied to the end crusher C4 can be supplied to the port 46 of the accumulator 43. [

When the manual valve 16 is in the reverse range, the hydraulic pressure supplied to the reverse first control line 50 is supplied to the low / reverse brake C5 (acting as a reaction force element at the reverse speed change stage) via the 1-2 shift valve 36 And the backward second control line 52 is connected to the manual valve 16 for the operation of the front clutch C3 acting as an input element.

The backward second control line 52 is provided with a check valve 53 to delay the release of the hydraulic pressure when releasing the operating hydraulic pressure, thereby improving the shifting feeling.

The kick-down servo C2 is provided with a kick-down switch 54 in the operating chamber to be turned off when hydraulic pressure is supplied to the operating chamber h1 and is controlled to be turned on when supplied to the releasing chamber h2, And to transmit the signal to the electronic control unit (TCU).

In the figure, reference numeral S5 denotes a solenoid valve for controlling the damper clutch control valve.

The hydraulic control apparatus includes three clutch means for transmitting rotational power by hydraulic pressure control, two brake means, and a shift planetary gear train having a complex planetary gear device employing a one-way clutch structurally rotatable only in one direction It is possible to perform the step control.

Since a known power train can be used, a description of the configuration of the power train will be omitted. However, what clutch means or brake means acts at each gear stage will be described.

Way clutch is restrained by the rear clutch C1 and the oil pressure control in the running (D) range 1 and the one-way clutch restrains rotation in the direction opposite to the input. In the second speed, the rear clutch C1 transmits power, The rear clutch C1 and the end clutch C4 both function as input elements and rotate to the gear train 1: 1 in the third speed, while the rear clutch C1 and the end clutch C4 rotate in the gear train 1: The downshift servo (C2) acts to realize the speed change stage control.

In the hydraulic control apparatus of the present invention thus configured, the following control is performed when downshifting to the third speed in the fourth speed is required.

That is, first, when the opening ratio of the throttle valve is lowered and the vehicle speed is lowered in the 4th speed running (D) range in the power-on state, the transmission control unit completes the 3-speed control through the control shown in FIG. .

That is, when the control for shifting is started, the transmission control unit TCU reads the signal transmitted through the ignition coil Ic in step S10 to sense the number of revolutions of the engine.

Subsequently, in step S12, the signal transmitted from the throttle position sensor TPS is read to determine the opening ratio of the throttle valve, and in step S14, it is determined whether or not the power is on.

When the driven condition is detected in the power-on state in the step S14, the transmission control unit controls both the first and second solenoid valves S1 and S2 to be in the off state, 28) (step S16) (see Figs. 5a and 5b)

The valve spool of the 2-3 / 4-3 shift valve 38 is shifted to the right in the drawing, and the 2-4 / 3 The valve spool of the fourth shift valve 40 is moved to the left in the drawing and the valve spool of the end clutch valve 42 is moved to the left in the drawing.

In step S18, the third and fourth solenoid valves S3 and S4 for controlling the first pressure control valve 20 and the second pressure control valve 22 are set to the initial duty ratio at power-on, S20), the control pressure is adjusted by varying the duty ratio of the third and fourth solenoid valves according to the change rate of the turbine rpm according to the set time at power-on.

By this control, the third solenoid valve S3 for controlling the first pressure control valve 20 supplies the control pressure to the operating chamber h1 of the kickdown servo C2.

At this time, the hydraulic pressure supplied to the release side chamber h2 of the end clutch C4 and the kick-down servo C2 is controlled by the control pressure from the second pressure control valve 22 controlled by the fourth solenoid valve S4. So as to be matched.

At this time, the kick-down servo C2 and the end clutch C4 are prevented from being released for the initial pressure reference (see FIG. 7).

The hydraulic pressure of the rear clutch C1, which acts as another input element at the third speed, is controlled by the fourth solenoid valve S4.

With such a series of actions, the operation of the rear clutch and the kick-down servo is released while the step S22 is realized. When the completion of the synchronization is determined in the step S24, the control is completed.

In other words, the hydraulic control state shown in FIG. 2 is shown. During this shifting, as shown in FIG. 4, the rotational speed of the turbine gradually increases over time.

On the other hand, if it is determined in step S14 that the power is off, both the first and second solenoid valves S1 and S2 are turned off in step S16-1.

The initial duty ratios of the third and fourth solenoid valves S3 and S4 at the time of power-off are set in step S18-1 and the initial duty ratio of the turbine speed The duty ratios of the third and fourth solenoid valves vary according to the rate of change.

When the completion of the synchronization is determined (step S24-1), the control is completed by performing the step S22-1 in which the rear clutch C1 is actuated and the action of the kickdown servo C2 is released by this action.

The end clutch C4 is supplied with the hydraulic pressure controlled by the second pressure control valve 22 and is supplied to the end clutch valve 42. [ The oil pressure controlled by the first pressure control valve 20 is supplied.

The number of revolutions of the turbine gradually increases over time as in the case of power-on at the time of power-off, and as shown in Figs. 10a and 10b, the first solenoid valve S1 and the second solenoid valve The first solenoid valve S1 is turned off after a lapse of a certain time (ts) than the power-on state, and the shift timing is delayed. This allows the tie-up control by giving the fourth-speed holding time.

As shown in FIGS. 11A and 11B, the third and fourth solenoid valves S3 and S4 are duty-controlled while shifting is started. When the fourth solenoid valve S4 is controlled to the maximum duty ratio The duty control of the third solenoid valve S3 is started.

When the fourth solenoid valve S4 is controlled to the lowest duty ratio, the third solenoid valve S3 is controlled to the maximum duty ratio. However, the duty ratio of the third solenoid valve S3 is rapidly lowered, whereas the fourth solenoid valve S3 S4, the duty ratio is gradually lowered, so that the release of the kick-down servo C2 is delayed as the operating pressure of the end clutch C4 is released as shown in Fig.

The rear clutch Cl is independently controlled. In particular, since the filling time of this clutch is longer than that of the other clutches, it is preferable to delay the termination of the kick-down servo.

As described above, the 4-3 downshift speed control method of the vehicular automatic transmission according to the present invention is capable of performing the shift control according to the driven condition and performing the tie-up control by giving the fourth-speed holding time at the time of power- , The rear clutch can be independently controlled, and the skip transmission can be performed.

Claims (2)

Port conversion is performed by solenoid valves which are controlled on / off by a transmission control unit, port conversion of shift valves for supplying or interrupting hydraulic pressure to / from each friction element is performed, and other solenoid valves are duty- A shift control method of a vehicular automatic transmission in which a control pressure is supplied to each friction element, comprising the steps of: sensing a revolution speed of an engine to perform a shift to a third speed when decelerated during fourth speed, Determining whether the driven state is a power-on state or an off-state state after the steps; and controlling the port conversion of the shift control valve when the power-on state is determined in the step Closing the first solenoid valve and the second solenoid valve to release the oil pressure of the fourth speed line, Controlling the third and fourth solenoid valves at an initial duty ratio at the time of power-on, and controlling the third and fourth solenoid valves controlled at an initial duty ratio at power-on in the step of controlling the rate of change of the turbine rpm And a step of changing the duty ratio according to the duty ratio of the vehicle, and completing the 4-3 downshift control when the friction elements are operated and deactivated through the steps described above, Down shift shift control method. The method as claimed in claim 1, wherein, in the step of determining the driven condition, when the determination value is determined as power-off, the first and second solenoid valves for controlling the port switching of the shift control valve are turned off, Controlling the first and third solenoid valves controlling the first and second pressure control valves to an initial duty ratio at the time of power-off; and controlling the third and fourth solenoid valves controlling the first and second pressure control valves at the initial duty ratio Changing a duty ratio of the solenoid valve according to a rate of change of the turbine speed according to a lapse of a predetermined time; and when the completion of the synchronous operation is determined by operating or releasing the corresponding friction element through the above steps, 4-3 downshift control And shifting the downshift of the automatic transmission to a downshift.