JP3102275B2 - Control device for lock-up clutch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling a lock-up clutch provided in a torque converter in an automatic transmission for a vehicle.

[0002]

2. Description of the Related Art It is well known that a torque converter having a built-in lock-up clutch is frequently used as a torque converter for an automatic transmission for a vehicle. Since the lock-up clutch mechanically directly connects the drive-side member and the driven-side member of the torque converter, a so-called lock-up clutch is engaged to improve fuel efficiency and ride comfort. The lockup region is set based on, for example, the vehicle speed and the throttle opening.

A lock-up clutch transmits engine torque directly to an automatic transmission.
In addition to the control based on whether or not the running state of the vehicle belongs to the lockup region, control according to the driving state of the engine is conventionally performed. For example, when the engine is in an idling state, the lock-up clutch is maintained in a released state in order to prevent a chip-in shock when the accelerator pedal is depressed to switch from idle ON to idle OFF.

At the time of switching from idle ON to idle OFF, in order to prevent a shock due to sudden engagement, the engagement force of the lock-up clutch is gradually increased by controlling the hydraulic pressure by a linear solenoid valve or the like. Specifically, the lock-up clutch is completely engaged (lock-up ON). An example of transitional control when engaging this type of lock-up clutch is
It is described in JP-B-63-24192.

[0005] FIG. 7 shows a state in which the idle state is changed to the idle state.
FIG. 9 is a time chart showing an example of control of the lock-up clutch in the case where the throttle switch is switched to the lock-up latch when the idle contact is closed and the lock-up latch is released (lock-up OFF); When the opening increases, the idle OF
At F, the lock-up signal is turned on, and the solenoid valve for the lock-up clutch is turned on. At the same time, the duty ratio of the linear solenoid valve SLU that controls the torque capacity of the lock-up clutch is maximized (100%). Is set to That is, the control hydraulic pressure of the lock-up clutch is set to a hydraulic pressure that releases the control hydraulic pressure. On the other hand, the engine speed NE is lower than the turbine speed NT in the idling ON state.
The engine speed NE increases from the turbine speed NT due to an increase in the throttle opening, and thereafter, the duty ratio of the linear solenoid valve SLU is gradually reduced to increase the torque capacity of the lock-up clutch, that is, gradually engage. As a result, the engine speed NE decreases, and when the lock-up clutch is engaged, the engine speed NE matches the turbine speed NT.

[0006]

As described above, in the case of switching from idle ON to idle OFF as described above, conventionally, the lock-up clutch is gradually engaged, and the increasing tendency of the engagement force is kept constant, or The setting was constant regardless of the driving condition.

However, from idle ON to idle O
Even when the mode is switched to FF, if the amount of depression of the accelerator pedal is small, the engine speed may be maintained at or below the turbine speed. When the load is equal to or less than the so-called load load, that is, when the engine is in a driven state, the relationship between the hydraulic pressure acting to engage the lock-up clutch and the torque capacity or the slip state of the lock-up clutch is a linear characteristic (linearity).
May deviate significantly. The cause is that in a so-called reverse drive state in which the rotation speed of the turbine runner is higher than the rotation speed of the pump impeller, the oil flow in the torque converter is opposite to that in the drive state. The state of the oil inside the torque converter or the state of the distribution of the hydraulic pressure, such as the distribution becomes significantly different from the normal case, or the state of oil leakage between the pump impeller and the turbine runner changes, etc. It is considered that the state greatly changes.

For this reason, the idle state is changed from the idle state to the idle state.
When the lock-up clutch is gradually engaged due to the switching to, the linearity between the hydraulic pressure for engagement and the torque capacity of the lock-up clutch is lost, and the torque capacity of the lock-up clutch is smoothly increased. A situation occurs in which the lock-up clutch does not increase or, conversely, the lock-up clutch suddenly engages. And this causes the engine speed to change rapidly,
There was a risk of shock.

The present invention has been made in view of the above circumstances, and when the engine is switched from idle-on to idle-off, even if the load is equal to or less than the load, the engine is locked without a sudden change in the engine speed. It is an object of the present invention to provide a control device capable of smoothly engaging an up clutch.

[0010]

According to the present invention, in order to achieve the above object, the lock-up clutch is maintained in a disengaged state if the state is equal to or less than a load load when the state is switched to idle OFF. The resultant force is maintained at a low engagement force.

That is, the first aspect of the present invention is shown in FIG.
When the engine 1 is switched from the idling state to the non-idling state, the lock-up clutch 5 for transmitting the torque between the driving member 3 and the driven member 4 in the fluid coupling 2 is gradually engaged from the disengaged state as shown in FIG. A control device for a lock-up clutch, comprising:
An idle-off detecting means 6 for detecting that the engine has switched from the idling state to the non-idling state, a comparing means 7 for comparing the engine speed with the speed of the driven member 4, and an engine speed not higher than the driven member speed. And a prohibiting means 8 for prohibiting the lock-up clutch 5 from being completely engaged until the difference between the rotational speeds becomes equal to or less than a predetermined set value including zero. It is.

Further, according to the present invention, as shown in FIG. 2, when the engine 1 is switched from the idling state to the non-idling state, the driving member 3 and the driven member 4 in the fluid coupling 2 are connected to each other. A lock-up clutch control device for gradually engaging the torque-transmitting lock-up clutch from a disengaged state, comprising: idle-off detecting means for detecting that the engine has switched from an idling state to a non-idling state; Means 7 for comparing the number of rotations of the driven member 4 with the number of rotations of the driven member 4, and the rate of increase of the engagement force of the lock-up clutch 5 when the number of rotations of the engine is lower than the number of rotations of the driven member 4. Force adjusting means 9 for reducing the rate of increase of the engaging force of lock-up clutch 5 when the number of rotations is equal to or greater than the rotation speed of driven member. That it comprises a and is characterized in.

[0013]

The lock-up clutch 5 of the present invention.
Is set to the released state when the engine 1 is in the idling state. When the engine 1 switches from the idling state to the non-idling state, the engine 1
The FF detection means 6 detects it, and the comparison means 7 compares the engine speed with the speed of the driven member 4. As a result of the comparison of the rotational speeds by the comparing means 7, when it is detected that the engine rotational speed is equal to or less than the driven member rotational speed, the lock-up clutch 5 is prohibited from being completely engaged by the prohibiting means 8. The prohibition control of the engagement of the lock-up clutch 5 is continued until the difference between the engine speed and the driven member speed becomes equal to or less than a predetermined set value including zero, that is, until the two speeds are substantially equal to each other. Thereafter, complete engagement of the lock-up clutch 5 is permitted. Therefore, when the lock-up clutch 5 is engaged, there is almost no difference between the engine speed and the speed of the driven member 4 in the fluid coupling 2. A sudden change does not occur, so that a shock can be prevented.

According to the second aspect of the present invention, if it is detected that the engine speed at the time of switching from the idle ON to the idle OFF is lower than the speed of the driven member 4, the idle speed is changed from the idle ON. Idle off
The rate of increase in the engagement force of the lock-up clutch 5 due to the switching to the above is set smaller than when the engine speed is equal to or higher than the driven member speed. That is, the engagement force of the lock-up clutch 5 is slowly increased in a state where the load is equal to or less than the load. This is achieved by slowing the rising speed of the hydraulic pressure for engaging the lock-up clutch 5, so that even if the linear characteristic between the engagement force of the lock-up clutch 5 and the hydraulic pressure is broken, the lock-up clutch 5 is prevented from suddenly engaging,
It is possible to prevent a sudden change in the engine speed and a shock resulting therefrom.

[0015]

Next, the present invention will be described based on embodiments. FIG. 3 is a block diagram schematically showing an embodiment of the present invention. An engine 10 is connected to a torque converter 11 with a lock-up clutch and an automatic transmission 13 mainly composed of a gear transmission 12. The engine 10 stops fuel supply during deceleration (fuel cut).
An engine having a conventionally known configuration capable of performing the following, and an electronic control unit for the engine (E-ECU) 1
4 is configured to electrically control fuel cut or ignition timing retard control for torque reduction during shifting. This engine electronic control unit 14
Central processing unit (CPU) and storage element (RAM,
ROM) and an input / output interface. Signals from the idle switch, water temperature, engine speed, throttle opening,
Other signals are being input.

On the other hand, the torque converter 11 includes a pump impeller 16 that rotates integrally with the front cover 15, a turbine runner 17 facing the pump impeller 16, and a predetermined fixed portion via a one-way clutch 18. , And a lock-up clutch 20 disposed facing the inner surface of the front cover 15. This lock-up clutch 20
Is connected to the input shaft 21 together with the turbine runner 17. The gear transmission 12 mainly includes a plurality of sets of planetary gear mechanisms, and sets a plurality of shift speeds by appropriately engaging a clutch or a brake (not shown) to change a torque transmission path. It is configured as follows.

The engagement of the lock-up clutch 20
Each control in the release state and the slip state, which is an intermediate state between them, and the shift control in the gear transmission 12 are executed by the hydraulic pressure controlled by the hydraulic control device 22. The hydraulic control device 22 is configured to control the hydraulic pressure for the lock-up clutch 20 and the hydraulic pressure for shifting by a solenoid valve, and an electronic device for an automatic transmission as a device that outputs a signal to the solenoid valve. A control device (T-ECU) 23 is provided. The electronic control unit 23 for the automatic transmission, like the electronic control unit 14 for the engine described above, mainly includes a central processing unit (CPU), storage elements (RAM, ROM), and an input / output interface. , The signal from the idle switch, the engine speed,
In addition to the throttle opening, a vehicle speed, a turbine speed, and other signals are input.

The electronic control unit 23 for the automatic transmission includes:
By sending a signal to the solenoid valve of the hydraulic control device 22 based on these input data and a control map stored in advance, the engagement / disengagement control and slip control of the lock-up clutch 20 and the slip control in the gear transmission 12 are performed. The shift control is performed. The electronic control unit 14 for the engine and the electronic control unit 23 for the automatic transmission are connected to each other so as to be able to communicate data with each other, and are necessary for the data necessary for the fuel cut control in the engine 10 or for the control of the lock-up clutch 20. Important data is communicated between the electronic control units 14 and 23.

Here, means for controlling the lock-up clutch 20 will be described. In FIG.
The oil chamber on the front cover side with the lock-up clutch 20 interposed therebetween serves as a release-side oil chamber 24.
The oil chamber on the opposite side of the release-side oil chamber 24 with respect to 0 is an engagement-side oil chamber 25. By supplying the hydraulic pressure from the release-side oil chamber 24 and discharging the pressure from the engagement-side oil chamber 25, the lock-up clutch 20 separates from the inner surface of the front cover 15 to be released, and supplies and discharges the hydraulic pressure in the opposite direction. By doing so, the lock-up clutch 20 is pressed against the inner surface of the front cover 15 to be in an engaged state. Further, by appropriately controlling the pressure difference of the hydraulic pressure between the release-side oil chamber 24 and the engagement-side oil chamber 25, the lock-up clutch 20 is brought into sliding contact with the front cover 15, so-called slip control. It is configured to be.

In FIG. 4, reference numeral 26 denotes a linear solenoid valve.
Is a modulator pressure Pmodu obtained by adjusting the line pressure.
Is adjusted in accordance with the duty ratio input from the electronic control unit 23, and the adjusted signal pressure Plin is output to the lock-up control valve 27. The lock-up control valve 27 uses the hydraulic pressure regulated by a secondary regulator valve (not shown) as a base pressure, regulates the pressure, and controls the lock-up relay valve 2.
The signal pressure Plin is input to a side opposite to the spring 29 across the spool. The oil pressure Poff of the release-side oil chamber 24 is applied to the same end as the signal pressure Plin, and the oil pressure Pon of the engagement-side oil chamber 25 is applied to the same side as the spring 29. That is, these oil pressures Plin, Poff, Pon
In addition, the pressure adjustment level is appropriately set by the elastic force of the spring 29, and the hydraulic pressure according to the pressure adjustment level is output.

Further, the lock-up relay valve 28
A valve which is switched by applying a line pressure PL selectively supplied by a solenoid valve 30 to an end opposite to a spring 31 with a spool interposed therebetween, wherein the valve is a regulator regulated by a secondary regulator valve. A first port 32 to which pressure PCl is supplied;
A second port 33 to which the hydraulic pressure output from the lock-up control valve 27 is supplied, a third port 34 connected to the release-side oil chamber 24, and a fourth port 35 connected to the engagement-side oil chamber 25. It has.

FIG. 4 shows the lock-up relay valve 28.
Is a state in which the solenoid valve 30 is controlled to be OFF. The first port 32 communicates with the third port 34 to supply the regulator pressure PCl to the release-side oil chamber 24, and the second port 33 Is closed and the fourth port 35 communicates with the drain port 36 to be discharged from the engagement side oil chamber 25. Accordingly, since the hydraulic pressure is supplied to the release-side oil chamber 24 and the pressure is released from the engagement-side oil chamber 35, the lock-up clutch 20 is separated from the inner surface of the front cover 15 to be in the released state.

On the contrary, when the solenoid valve 30 is
When the N control is performed, hydraulic pressure is applied to the lock-up relay valve 28 in a direction opposite to the spring 31 to move the spool, so that the first port 32 communicates with the fourth port 35 and the second port 33 is connected to the third port 35. 34. Therefore, the regulator pressure PCl is
And the hydraulic pressure regulated by the lock-up control valve 27 is supplied to the release-side oil chamber 24.
Therefore, if the pressure adjustment level of the lock-up control valve 27 is lowered to lower the oil pressure of the release-side oil chamber 24, the lock-up clutch 20 is pressed against the inner surface of the front cover 15 to be engaged. On the other hand, if the pressure adjustment level of the lock-up control valve 27 is increased, the oil pressure in the release-side oil chamber 24 is increased, so that the load pressing the lock-up clutch 20 against the inner surface of the front cover 15 is reduced, and as a result, The up clutch 20 is slip-controlled.

When the engine 10 is in the idling state, that is, when the engine 10 is in the idling ON state, the lock-up clutch 20 is maintained in the disengaged state in order to prevent a chip-in shock as in the conventional case. When the accelerator pedal (not shown) is depressed to increase the throttle opening, that is, when the idle
, The lock-up clutch 20 is gradually engaged, but in the above-described control device according to the present invention,
The control for engaging the lock-up clutch 20 is executed as described below without performing control based only on switching from idle ON to idle OFF.

FIG. 5 is a flowchart showing an example of the control routine.
When the lock-up clutch 20
It is determined whether or not is engaged (whether or not lock-up is ON) (step 1). If the lock-up clutch 20 has been released, it is determined whether or not the difference NSLP (= NE-NT) between the engine speed NE and the turbine speed NT is equal to or greater than "0" (step 2). If the result of the determination in step 2 is "NO", the turbine speed NT, which is a driven member, is larger than the engine speed NE.
In this case, lock-up OFF control for releasing the lock-up clutch 20 is executed (step 3). That is, according to the control device of the present invention, even if the engine is switched from idle ON to idle OFF, the engine speed N
If E does not rise sufficiently and is equal to or lower than the turbine speed NT, the lock-up clutch 20 is maintained in the released state even in the idle-off state.

On the other hand, if the deviation NSLP between the engine speed NE and the turbine speed NT is "0" or more, this means that the engine speed NE is sufficiently increased.
In this case, it is determined whether or not the running state is in the lock-up area (step 4). If the driving state is in the lockup area, the lockup clutch 2
0 is engaged (lock-up ON control) (step 5). On the other hand, if not in the lock-up area, proceed to step 3 to lock-up OFF.
Execute control.

It should be noted that the determination result of step 1 is "yes"
In other words, when the lock-up clutch 20 is engaged, it is determined whether or not the traveling state is in the lock-up OFF area (step 6). To execute the lock-up OFF control. Lock-up OFF
If not, the process proceeds to step 5 to execute the lock-up ON control.

The above-described control routine of FIG. 5 is repeatedly executed at predetermined time intervals. Therefore, after switching from idle ON to idle OFF, since the engine speed NE is lower than the turbine speed NT, lock-up occurs. Even if the clutch 20 is maintained in the disengaged state, the engine speed gradually increases because the accelerator pedal is depressed and the idle is turned off, and as a result, the result of the determination in step 2 becomes “yes”. For example, the lock-up ON control is executed on condition that the running state at that time is in the lock-up area.

Therefore, according to the control shown in FIG. 5, the lock-up clutch is maintained in the disengaged state in a state below the load load after the idle-off, and in the hydraulic circuit shown in FIG. Not supplied. As a result, since the hydraulic pressure is not applied so as to engage the lock-up clutch in a state where the linear characteristic (linearity) between the control oil pressure and the torque capacity of the lock-up clutch is broken, the lock-up clutch 20 is rapidly engaged. This prevents the occurrence of a shock due to a sudden change in the engine speed NE.

In the control example shown in FIG. 5, the difference NSLP between the engine speed NE and the turbine speed NT is "0".
The lock-up OFF control is executed when the difference is smaller than the reference value. However, the reference value for judging the deviation NSLP is "0".
Is not particularly necessary, and a predetermined number α close to “0” may be used as the criterion value.

According to the control shown in FIG. 5, if the engine speed NE is larger than the turbine speed NT, the lock-up ON control is executed. This is the same as the control shown in FIG. is there. Accordingly, the lock-up ON control in step 5 is a control in which the hydraulic pressure for engaging the lock-up clutch 20 is gradually increased, and finally the lock-up clutch 20 is completely engaged.

On the other hand, the lock-up OF in step 3
The F control includes controlling the lock-up clutch 20 to be in a state in which the lock-up clutch 20 does not suddenly engage under a load condition. Including controlling to slip on the cover.

By the way, the possibility that the lock-up clutch 20 is suddenly engaged under a load or less is determined by the smaller the difference NSLP between the engine speed NE and the turbine speed NT (the larger the negative value and the larger the absolute value). )high,
Conversely, when the engine speed NE approaches the turbine speed NT, the possibility that the lock-up clutch is suddenly engaged will be reduced even if the hydraulic pressure for engaging the lock-up clutch 20 becomes somewhat high. Therefore, the oil pressure may be controlled in a direction in which the lock-up clutch 20 is engaged within a range in which the lock-up clutch 20 does not suddenly engage even in a state where the load is equal to or less than the load. An example is shown in a time chart in FIG.

In FIG. 6, when the accelerator pedal is depressed and the throttle opening θ increases, it is determined to switch from idle ON to idle OFF, and at the same time, a lock-up ON signal is output. Then, an ON signal is output to the solenoid valve 30 shown in FIG. At the same time, the duty ratio of the linear solenoid valve 26 is set to the maximum (100%). As a result, the pressure regulation level of the lock-up control valve 27 increases, and a high oil pressure is supplied to the release-side oil chamber 24, so that the lock-up clutch 20 is released.

If the throttle opening is small due to the small amount of depression of the accelerator pedal and the engine speed NE is smaller than the turbine speed, the reduction ratio of the duty ratio of the linear solenoid valve 26, that is, the lock-up clutch 20 is engaged. The increase rate of the oil pressure is controlled at a gentle gradient as shown by a broken line in FIG. Therefore, although the engine speed NE increases to a speed corresponding to the opening degree θ by increasing the throttle opening degree θ, the engine speed NE does not increase to a certain degree or more because the engagement force of the lock-up clutch 20 is low. When the ratio gradually decreases to a predetermined value or less, in other words, when the lock-up clutch 20 gradually engages and starts to have a large torque capacity, the engine speed NE is so-called raised and gradually approaches the turbine speed. . This is as indicated by the broken line in FIG. 6. After the engine speed NE matches the turbine speed NT, the duty ratio is reduced to "0", and the lock-up clutch 20 is completely engaged.

In FIG. 6, the change of the duty ratio of the solenoid valve 26 indicated by a solid line is based on the conventional control, and is a value larger than the reduction ratio of the duty ratio, that is, the increase ratio of the engagement force of the lock-up clutch 20 according to the present invention. It has become. This is from idle ON to idle OF
F, the control is the same as that performed when the engine speed NE is higher than the turbine speed NT when the lock-up clutch 20 is so suddenly engaged. Up clutch 20
If the rise of the hydraulic pressure to engage
As shown by the solid line in FIG. 6, the engine speed NE sharply increases to the turbine speed NT with the sudden increase in the engagement force of the lock-up clutch 20, and as a result, the engine speed NE increases as shown in FIG. A sudden change appears as a shock, which impairs ride comfort. The control device of the present invention eliminates such inconvenience by slowing the rise of the hydraulic pressure for engaging the lock-up clutch 20.

The present invention is not limited to the above embodiment, and a hydraulic circuit for controlling the lock-up clutch may have a structure other than that shown in FIG. For example, the lock-up relay valve 28 may be switched and controlled by the signal pressure of the linear solenoid valve 26 without using the solenoid valve 30. Further, the linear solenoid valve 26 may be configured to output a signal pressure according to a current value, instead of a configuration that outputs a signal pressure according to a duty ratio.

[0038]

As described above, according to the lock-up clutch control device of the present invention, even when the engine is switched from idle-on to idle-off, the load at which the engine speed is lower than the turbine speed is reduced. When the load is equal to or less than the load, the lock-up clutch is maintained in the disengaged state, or the rise of the hydraulic pressure for engaging the lock-up clutch is slowed down. It is possible to prevent a situation such as an increase, and to avoid a shock accompanying it, thereby preventing a deterioration in ride comfort.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the invention described in claim 1 by functional means.

FIG. 2 is a block diagram showing the invention described in claim 2 by functional means.

FIG. 3 is a block diagram schematically showing one embodiment of the present invention.

FIG. 4 is a hydraulic circuit diagram showing a hydraulic circuit for controlling a lock-up clutch.

FIG. 5 is a flowchart illustrating an example of a lock-up clutch ON / OFF control routine according to a deviation between an engine speed and a turbine speed after switching from idle ON to idle OFF.

FIG. 6 is a time chart showing an example of controlling the duty ratio according to the present invention after switching from idle ON to idle OFF in comparison with a conventional example.

FIG. 7 is a time chart showing a general control example of the duty ratio when the engine speed after switching from idle ON to idle OFF is higher than the turbine speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Fluid coupling 3 Driving member 4 Follower member 5 Lock-up clutch 6 Idle-OFF detecting means 7 Comparison means 8 Inhibiting means 9 Engaging force adjusting means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-63/48

Claims (2)

(57) [Claims] When the engine is switched from an idling state to a non-idling state, control of a lock-up clutch that gradually engages a lock-up clutch for transmitting torque between a driving member and a driven member in a fluid coupling from a disengaged state. An idle-off detecting means for detecting that the engine has switched from an idling state to a non-idling state; a comparing means for comparing the engine speed with the speed of the driven member; and Lock-up means for prohibiting the lock-up clutch from completely engaging until the difference between the rotation speeds becomes equal to or less than a predetermined set value including zero in the following cases: Control device for clutch. 2. The control of a lock-up clutch for gradually engaging a lock-up clutch for transmitting torque between a driving member and a driven member in a fluid coupling from a disengaged state when the engine is switched from an idling state to a non-idling state. An idle-off detecting means for detecting that the engine is switched from an idling state to a non-idling state; a comparing means for comparing an engine speed with a rotation speed of the driven member; And an engaging force adjusting means for decreasing the rate of increase of the engaging force of the lock-up clutch when the number of revolutions is lower than the number of revolutions less than the rate of increase of the engaging force of the lock-up clutch when the engine speed is equal to or greater than the number of revolutions of the driven member. A lock-up clutch control device, comprising: