JPH1047472A - Lockup-clutch slip controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the transmission of torque fluctuations of an engine to the automatic transmission after the start of slip control for the lockup clutch as well as before the start of fuel-cut control. SOLUTION: A controller controls the slip of a lockup clutch by feedforward control at deceleration, the fuel cut of interrupting the supply of fuel to the engine after the start of the slip control, and the feedforward and the feed back for the lockup clutch. The controller is provided with an engaging-pressure control means or step 3 for controlling the engaging pressure of the lockup clutch by setting a target slip value obtained by the feedforward control of the lockup clutch before the start of the fuel-cut control larger than a target slip value obtained by the feedforward control after the start of the fuel-cut control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock-up clutch slip control device for slip-controlling a lock-up clutch disposed in a torque transmission path between an engine and an automatic transmission. The present invention relates to a lock-up clutch slip control device in which a fuel cut control and a slip control for shutting off are performed in parallel.

[0002]

2. Description of the Related Art Conventionally, in a vehicle in which a lock-up clutch is disposed in a torque transmission path between an engine and an automatic transmission, the rotational speed of the engine during deceleration is controlled by a rotational speed set for the purpose of fuel cut control. In order to expand the fuel cut region by controlling the lock-up clutch higher than in the prior art, there is known a technique of performing slip control of a lock-up clutch. Thus, an example of a lock-up clutch slip control device in which the slip control and the fuel cut control are performed in parallel during deceleration traveling is disclosed in JP-A-8-34265.
No., published in Japanese Unexamined Patent Publication No.

[0003] The slip control device for a lock-up clutch described in this publication has an automatic transmission connected to an engine via a torque converter having a built-in lock-up clutch, and an electronic control device for controlling the engine and an automatic transmission. And a hydraulic control device for controlling a lock-up clutch. The control device controls the lock-up clutch to an engaged state, a released state, and a slip state.

An electronic control unit for the engine controls a fuel injection valve and an igniter on the engine side based on detection signals such as an engine rotation speed and a throttle opening, and based on detection signals such as a throttle opening and a vehicle speed. ,
The electronic control unit for shifting controls the hydraulic control circuit.
The electronic control unit for the engine and the electronic control unit for shifting are connected to each other so as to be able to perform data communication.

The hydraulic control circuit includes a solenoid valve for generating a switching signal pressure, a lock-up relay valve for engaging and disengaging a lock-up clutch by the switching signal pressure, and a linear valve for generating a slip control signal pressure. A solenoid valve and a lock-up control valve that adjusts a pressure difference between the engagement-side oil chamber and the release-side oil chamber in accordance with a slip control signal pressure to control a slip amount of a lock-up clutch.

In the slip control device of the lock-up clutch described in the above publication, slip control of the lock-up clutch is started based on the opening of the throttle valve and the output shaft rotation speed of the automatic transmission when the vehicle is decelerated. . Then, after the start of the slip control, fuel cut control for closing the fuel injection valve based on the engine speed is started.

Here, the slip control is started, and
The engagement pressure of the lock-up clutch before the start of the fuel cut control is set by feedforward control based on the engine load after the start of the fuel cut control.
Further, the engagement pressure of the lock-up clutch after the start of the fuel cut control, that is, the torque capacity can be maintained at a value equal to or higher than the value set for the fuel cut control by the torque input from the wheel side due to the inertial force. Thus, the setting is performed by using both the feedforward control and the feedback control.

[0008]

From the start of the slip control of the lock-up clutch to the start of the fuel cut control, the combustion of the engine is unstable because the throttle valve is fully closed. Has become.

However, in the above-described conventional device, the engagement pressure of the lock-up clutch changes the engine rotation speed by the torque input from the wheels from the start of the slip control of the lock-up clutch to the start of the fuel cut control. Set to a value that can be maintained at a predetermined rotation speed, practically,
The lock-up clutch is controlled to the engaged state. Therefore, during the slip control of the lock-up clutch, fluctuations in engine torque due to unstable combustion of the engine are transmitted to the automatic transmission via the lock-up clutch to generate a shock or muffled sound, thereby reducing ride comfort. There was a possibility.

[0010] The present invention has been made in view of the above-described circumstances, and the torque fluctuation generated on the engine side from the start of the slip control of the lock-up clutch to the start of the fuel cut control on the automatic transmission side. It is an object of the present invention to provide a lock-up clutch slip control device that can suppress transmission.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention reduces the speed of a lock-up clutch arranged in parallel with a fluid transmission connecting an engine and an automatic transmission. A slip control device for a lock-up clutch that executes a fuel cut control for shutting off the supply of fuel to the engine after the start of the slip control and feed-forward and feedback-controls the lock-up clutch after the start of the slip control. In the slip control, the target slip value by the feed-forward control of the lock-up clutch before the start of the fuel cut control during the slip control is determined by the target in the feed-forward control of the lock-up clutch after the start of the fuel cut control. And it is characterized in that it comprises an engagement pressure control means for controlling the increase to the lock-up clutch engagement pressure than the slip value.

Therefore, according to the present invention, during the period from the start of the slip control of the lock-up clutch to the start of the fuel cut control during deceleration running of the vehicle,
Since the feedforward value is set so that the target slip amount of the lock-up clutch becomes larger than after the start of the fuel cut control, a decrease in the engagement pressure of the lock-up clutch is promoted. Even if the combustion state becomes unstable and a torque fluctuation occurs, the fluctuation in the engine torque is attenuated or absorbed by the slip of the lock-up clutch, and is not transmitted to the automatic transmission side. As a result, shock and muffled noise are suppressed, and riding comfort is improved.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be specifically described with reference to the drawings. First, the overall control system of a vehicle targeted by the present invention will be briefly described.
An automatic transmission 2 controlled by oil pressure is connected to an output side of an engine 1 which is an internal combustion engine. Engine 1
The output is controlled by both manual operation and electric control. The intake pipe 3 has a main throttle valve 5 connected to an accelerator pedal 4 by mechanical means such as a cable. A sub-throttle valve 7 whose opening is changed by a throttle actuator 6 such as a servomotor is disposed upstream of the main throttle valve 5. The sub-throttle valve 7 is normally set to a fully open state, and the engine output is adjusted by changing the opening of the main throttle valve 5 in accordance with the amount of depression of the accelerator pedal 4, so that the sub-throttle valve 7 can be operated without manual operation. When it is necessary to reduce the engine output, the sub-throttle valve 7 is electrically controlled to reduce its opening.

An electronic control unit 8 for controlling the engine 1 including the degree of opening of the sub-throttle valve 7 is provided. The electronic control unit 8 mainly includes a central processing unit (CPU), a storage unit (RAM, ROM) and an input / output interface. The electronic control unit 8 includes a depression of the accelerator pedal 4. In addition to the signal corresponding to the amount, the output signal of the engine rotational speed sensor 9, the output signal of the intake air amount sensor (air flow meter) 10, the output signal of the intake air temperature sensor 11, the output signal of the throttle opening sensor 12, An output signal of the vehicle speed sensor 13, an output signal of the coolant temperature sensor 14, an output signal of the brake switch 15, and the like are input as control data. The electronic control unit 8 for the engine
Is configured to output a signal to the fuel injection device 16, an igniter 17 for changing the ignition timing, and the like for torque control at the time of gear shifting, in addition to the control of the throttle actuator 6, as described above.

The automatic transmission 2 connected to the engine 1 is connected to the engine 1 via a torque converter which is a fluid transmission device having a lock-up clutch described later. A hydraulic control device 18 for changing the gear position and controlling the lock-up clutch is provided. The hydraulic control device 18 mainly includes first to third solenoid valves S1 and S2 for setting the gear position.
, S3, a fourth solenoid valve S4 for controlling the engine braking state, and a linear solenoid valve SLU mainly for controlling the lock-up clutch,
A linear solenoid valve SLT for controlling the line pressure according to the throttle opening, and a linear solenoid valve SLN for mainly controlling the back pressure of the accumulator are provided.

An electronic control unit 19 for an automatic transmission for outputting a control signal to each solenoid valve in the hydraulic control unit 18 is provided. The electronic control unit 19 for the automatic transmission includes a central processing unit (CPU) and a storage unit (RA), like the electronic control unit 8 for the engine described above.
M, ROM) and an input / output interface, and therefore can be integrated with the engine electronic control unit 8 as needed. The electronic control unit 19 for the automatic transmission performs a calculation based on the input data according to a map or a calculation formula stored in advance, and outputs a control signal based on the calculation result to each of the solenoid valves to output, for example, four forward gears. It is configured to execute one-step reverse gear shift, control of engagement / disengagement of the lock-up clutch, control of transient hydraulic pressure during gear shift, and the like.

The electronic control unit 19 for the automatic transmission includes, as control data, the throttle opening sensor 1 described above.
2, the output signal of the vehicle speed sensor 13, the output signal of the coolant temperature sensor 14, the output signal of the brake switch 15, the signal from the shift position sensor 21 provided in the shift device 20, the turbine of the torque converter A signal from the rotation speed sensor 22, a signal from the oil temperature sensor 23, and the like are input. Each of the above electronic control devices 8, 1
Numerals 9 are connected so as to be able to communicate with each other, and a signal for setting each shift speed is transmitted from the electronic control unit 19 for the automatic transmission to the electronic control unit 8 for the engine.

Next, a torque converter 24 and a lock-up clutch 25 built therein will be described with reference to FIG. This torque converter 24 has basically the same configuration as that used in a normal automatic transmission, and faces a pump impeller 27 integrated with a front cover 26 connected to the engine 1. A turbine runner 28 is disposed, and a spiral flow of fluid (oil) generated by rotation of the pump impeller 27 is given to the turbine runner 28 to rotate the same.
It is configured to transmit torque between the two. Further, the pump impeller 27 and the turbine runner 28
Between them, a stator 30 supported via a one-way clutch 29 on a fixed shaft (not shown) integrated with the casing is arranged.

The lock-up clutch 25 is arranged in parallel with a fluid transmission constituted by the pump impeller 27, the turbine runner 28 and the stator 30. More specifically, the lock-up clutch 25 faces the inner surface of the front cover 26. And is attached to a hub or an input shaft (each not shown) so as to rotate integrally with the turbine runner 28. The lock-up clutch 25 is pressed against the front cover 26 by hydraulic pressure so that the front cover 26
A torque is transmitted between the lock-up clutch 25 and the front cover 26 as a release oil chamber 31 with the lock-up clutch 25 interposed therebetween, and the opposite side (turbine runner 28) is engaged oil. A room 32 is provided.

Therefore, by supplying the hydraulic pressure to the engagement oil chamber 32 and discharging the pressure from the release oil chamber 31, the lock-up clutch 25 is pressed against the front cover 26 and fully engaged. By increasing the hydraulic pressure, the pressure (engagement force) for pressing the lock-up clutch 25 against the front cover 26 is reduced, causing a slip state, and further releasing the pressure from the engagement oil chamber 32 while supplying the oil pressure to the release oil chamber 31. Thus, the lock-up clutch 25 is configured to be separated from the front cover 26 to be released.

As described above, the lock-up clutch 25
Is controlled by a linear solenoid valve SLU. That is, in FIG. 4, reference numeral 33 denotes a solenoid relay valve, and the solenoid relay valve 33 has a shift speed higher than a predetermined middle speed (for example, third to fourth speeds).
Is applied to the control port so that the input port 34 communicates with the output port 35. The input port 34 is connected to a linear solenoid valve SLU, and the output port 35
Are connected to a control port 37 of a lock-up relay valve 36 described later.

In FIG. 4, reference numeral 38 denotes a lock-up control valve. This lock-up control valve 38 regulates the line pressure PL so as to output it as a release pressure (L / U OFF pressure) of the lock-up clutch 25. It is configured. That is, the lock-up control valve 38 is a valve provided with a spool pressed in one direction by a spring, and a first control port 39 formed to open at one end of the spool communicates with the release oil chamber 31. A linear solenoid valve SLU is connected to a second control port 40 formed adjacent to the first control port 39. Further, a signal pressure port 41 is formed on the opposite side of the control ports 39 and 40 across the spool, and the signal pressure port 41 is connected to the engagement oil chamber 32. The line pressure PL supplied to the input port 42 is regulated according to the difference between the hydraulic pressure applied to the control ports 39 and 40 and the hydraulic pressure applied to the signal pressure port 41, and is output from the output port 43. Is configured.

As shown in FIG. 5, the linear solenoid valve SLU is configured such that the output pressure PSLU gradually decreases as the duty ratio DSLU increases, and the lock-up control valve 38 controls the second control valve. The higher the hydraulic pressure applied to the port 40, the higher the pressure regulation level and the higher the output pressure. Therefore, the output pressure of the lock-up control valve 38 is controlled to be lower as the duty ratio DSLU of the linear solenoid valve SLU is larger.

The lock-up relay valve 36 will be further described.
Selectively supplies the oil pressure adjusted by a secondary modulator valve (not shown) to the release oil chamber 31 and the engagement oil chamber 32, and selects the oil pressure adjusted by the lock-up control valve 38 to the release oil chamber 31. A secondary modulator pressure PSM is supplied to a first input port 44, and a second input port 45 is connected to an output port 43 of the lock-up control valve 38. I have. On the other hand, a first output port 46 selectively connected to the first input port 44 is connected to the engagement oil chamber 32, and is selectively switched to the first and second input ports 44 and 45. A second output port 47 is connected to the release oil chamber 31. Reference numeral 48 indicates a third output port, and the third output port 48 is connected to an oil cooler (not shown).

The lock-up relay valve 36 is
When the hydraulic pressure output from the solenoid relay valve 33 is supplied to the control port 37, the first input port 44 communicates with the first output port 46 in the on state, and the second input port 44 communicates with the second output port 46.
The input port 45 is configured to communicate with the second output port 47. Accordingly, in this state, the secondary modulator pressure PSM is supplied to the engagement oil chamber 32 of the lock-up clutch 25, the lock-up clutch 25 is brought into the engagement state, and the adjusted oil pressure acts on the release oil chamber 31. Thus, the engagement pressure (engagement force) of the lock-up clutch 25 is appropriately controlled. FIG. 6 shows the relationship between the engagement pressure and the output pressure PSLU of the linear solenoid valve SLU.

In the OFF state in which no oil pressure is supplied to the control port 37, the first output port 46 is communicated with the third output port 48 and drained from the engagement oil chamber 32,
Further, the second output port 47 is connected to the first input port 44, the secondary modulator pressure PSM is supplied to the release oil chamber 31, and the lock-up clutch 25 is released.

The engagement, release and slip control of the lock-up clutch 25 set as described above are controlled by the vehicle speed (output shaft speed NO), the opening of the main throttle valve 5 (throttle opening) θ, Is executed in accordance with the area set as a parameter. More specifically,
The electronic control unit 1 for the automatic transmission is used for the map that defines this area.
9 is stored in advance, and when the traveling state determined based on the input data enters one of the regions, the control of the lock-up clutch 25 according to the region is executed. . An example of a map in which the region is set is as shown in FIG. In this embodiment, the lock-up clutch 25 is engaged or slip controlled at the third and fourth forward speeds.

In the deceleration slip control described above, the rotational speed of the engine 1 is maintained at a relatively high rotational speed by the inertia of the vehicle, and fuel cut is performed to improve fuel economy. It is executed for the purpose of preventing shock and vibration caused by unstable combustion. When shifting from the state in which the lock-up clutch 25 is completely engaged to the deceleration slip, if there is a response delay in controlling the engagement pressure of the lock-up clutch 25, the lock-up clutch does not transiently enter the slip state. In addition, there is a possibility that a change in the output torque of the engine 1 is transmitted to the automatic transmission 2 as it is. Therefore, at the start of the slip control, the engagement pressure of the lock-up clutch 25 is controlled by feedforward control as in the above-described conventional device. After the engagement pressure of the lock-up clutch 25 reaches the target pressure in the slip control, The feed pressure and the feedback control of the engagement pressure are performed while executing the fuel cut. In that case, the above control device according to the present invention performs control as described below.

FIG. 1 is a flowchart showing an example of the control routine, and FIG. 2 is a time chart when the control is performed. This control example is an example of executing the deceleration slip control by returning the accelerator pedal 4 when the accelerator pedal 4 is depressed to accelerate. When the accelerator pedal 4 is depressed, fuel cut is not performed (fuel is not performed). Cut OFF), and the ignition timing retard control is not executed. Further, the lock-up clutch 25 is in a completely locked-up state, the duty ratio DSLU of the linear solenoid valve SLU is set to 100%, and the hydraulic pressure (L / U OF
F pressure) is drained.

In this state, it is determined whether or not a deceleration slip start condition is satisfied (step 1). This decision
For example, when the throttle opening becomes zero when the vehicle is running with the lock-up clutch 25 controlled to the complete lock-up state, the start condition is satisfied. If a negative determination is made, this control routine is ended. Conversely, if a start condition is satisfied and an affirmative determination is made in step 1, it is determined whether or not fuel cut control is being executed (step 2). ).

In the fuel cut, usually, when the engine speed is equal to or higher than a predetermined lower limit speed and the throttle valve 5
Is executed when the accelerator pedal 4 is closed. Therefore, when the accelerator pedal 4 is returned while the accelerator pedal 4 is depressed and accelerated as described above, the fuel cut is not executed, and a negative determination is made in step 2. You. This is the time point t0 in FIG. 2. When the throttle opening becomes zero, the conditions for starting the deceleration slip are satisfied, and the feedforward control for controlling the lock-up clutch 25 to the slip state is executed.

Specifically, the linear solenoid valve SLU
Duty ratio DSLU is the feed forward value DFWD1
And the product of the learning value KGD and the coefficient α (DFWD1 + α
KGD) (step 3). Here, the feed forward value DFWD1 is a value for controlling the linear solenoid valve SLU so that the engagement pressure becomes sufficiently low to bring the lock-up clutch 25 into the slip state. The target value is a slip amount larger than the target slip amount in the feedforward control after the start. The learning value K
GD is a learning control value formed corresponding to characteristics of each machine at the time of feedback control described later, and further includes a coefficient α
Is, for example, a value smaller than "1" obtained experimentally. Therefore, the control value at the time of feedforward control is a value corrected by reflecting the learning correction amount at the time of feedback control. Step 3 corresponds to the engagement pressure control means in the present invention.

The state in which the duty ratio DSLU of the linear solenoid valve SLU is controlled as described above is shown by a broken line in FIG. 2. By controlling in this manner, the engagement pressure (transmission torque capacity) of the lock-up clutch 27 is reduced. Therefore, even if unstable combustion occurs in the engine 1 due to the closing of the throttle valve 5, the torque fluctuation causes the lock-up clutch 25 to slip as shown by the broken line in FIG. The torque fluctuation is absorbed or cut off, and the output shaft torque changes smoothly as shown by a broken line in FIG. That is, factors that deteriorate ride comfort such as shock and vibration are eliminated.

In parallel with the above control, the ignition timing is retarded. This is executed for the purpose of reducing the engine torque in advance in order to reduce the torque fluctuation width when executing the subsequent fuel cut.

After the control for lowering the engagement pressure of the lock-up clutch 25 and the control for retarding the ignition timing have been performed for a predetermined time, the fuel cut control is executed. The duration of the control for lowering the engagement pressure of the lock-up clutch 25 is as follows:
This is a time set in advance as a time required to complete the decrease in engine output due to the closing of the throttle valve 5. At time t1 when this time has elapsed, control by feedforward and feedback of the engagement pressure of the lock-up clutch 25 is started, and simultaneously, fuel cut control is started. That is, when the determination in step 2 is affirmative, the routine proceeds to step 4 where the duty ratio DSLU of the linear solenoid valve SLU is set to a value (DFWD2 + DFB + KGD) obtained by adding the feedback value DFB and the learning value KGD to the feedforward value DFWD2.

Here, the feedforward value DFWD2 is a value larger than the feedforward value DFWD1 before the start of the fuel cut control, and the feedback value DFB is added to or subtracted from the feedforward value DFWD2 to determine the duty ratio DSLU. The target slip amount at this time is a slip amount that can maintain the engine rotation speed to some extent and can cut off the torque fluctuation of the engine 1, and as an example, 50 rpm
This is a slip amount at which a slight difference in the number of rotations occurs. Note that the ignition timing retard control is ended simultaneously with the start of this control.

As described above, the present invention has been described based on the specific examples. However, the present invention is not limited to the above examples.
Therefore, the configuration of the hydraulic circuit that controls the lock-up clutch 25 may be other than the configuration shown in FIG. 4. For example, the switching operation of the lock-up relay valve 36 may be performed by a third solenoid valve or other linear solenoid valve. May be configured to be controlled by the solenoid valve. Further, the fluid transmission device targeted by the present invention is not limited to a torque converter having a torque amplifying action, and may be a fluid coupling functioning as a simple joint.

Further, in the above-described embodiment, the case of shifting from the complete lock-up state to the deceleration slip control has been described as an example. However, the case where the lock-up clutch is released when the accelerator pedal is depressed by a large amount is described. Therefore, if the accelerator pedal is returned from this state, the deceleration slip control is performed from the released state of the lock-up clutch, and the present invention can be applied to the control in this case. In any case, according to the present invention, the lock-up clutch before the deceleration slip is not limited to the complete lock-up state.

[0039]

As described above, according to the present invention, the slip control of the lock-up clutch is performed by the feedforward control at the time of deceleration, and the fuel cut control is started after the elapse of a predetermined time. In performing the feedback control, the target slip value by the feedforward control during the slip control before the start of the fuel cut control is made larger than the target slip value by the feedforward control after the start of the fuel cut control, and immediately after the start of the deceleration slip control of the lock-up clutch. In this case, even if torque fluctuation due to unstable combustion occurs in the process of lowering the engine output, the torque fluctuation is absorbed or interrupted by the slip of the lock-up clutch. Ride deterioration factors such as shock and vibration due to the slip control can be eliminated in advance.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of a control routine according to the present invention.

FIG. 2 is a diagram showing an example of a time chart when the control shown in FIG. 1 is executed.

FIG. 3 is a block diagram schematically illustrating an example of a control system to which the present invention is applied;

4 is a diagram showing an example of a hydraulic circuit for controlling a lock-up clutch of the automatic transmission shown in FIG.

FIG. 5 is a diagram showing a relationship between a duty ratio of a linear solenoid valve and an output pressure.

FIG. 6 is a diagram showing a relationship between an output pressure of a linear solenoid valve and an engagement pressure of a lock-up clutch.

FIG. 7 shows an engagement area, a release area, and a lock-up clutch.
It is a figure showing an example of a map which set a slip control field.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Automatic transmission 2 Engine 8 Engine electronic control unit 16 Fuel injection valve 19 Automatic transmission electronic control unit 25 Lock-up clutch

Claims (1)

[Claims] A slip-up control of a lock-up clutch, which is arranged in parallel with a fluid transmission device connecting an engine and an automatic transmission, by feed-forward control with deceleration, and after the slip control is started, the lock-up clutch is locked to the engine. A slip control device for a lock-up clutch, which performs fuel cut control for shutting off fuel supply and feed-forwards and feedback-controls the lock-up clutch, wherein the feed of the lock-up clutch before the start of fuel cut control during the slip control. Engagement to control the engagement pressure of the lock-up clutch by making the target slip value by forward control larger than the target slip value by feed-forward control of the lock-up clutch after the start of the fuel cut control. Slip lockup clutch control apparatus which is characterized in that it comprises a control means.