JP2795118B2 - Control device for torque converter with 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 a control device for a torque converter with a lock-up clutch, which is provided in a vehicle power transmission device.

[0002]

2. Description of the Related Art Conventionally, in a vehicle equipped with a torque converter with a lock-up clutch, an engagement region and a release region of the lock-up clutch are used to absorb fluctuations in engine torque during low-speed running and to improve fuel efficiency. Are provided so as to secure a predetermined slip amount between an input side (engine output shaft) of a torque converter and an output side (input shaft of a transmission mechanism) (see FIG. 1). See JP-A-64-58858).

In this case, the amount of slip between the input side and the output side of the torque converter (the difference in rotational speed between the input side and the output side) is detected, and feedback control is performed so that the detected slip amount approaches a target value. ing.

[0004]

When the throttle is suddenly returned during the slip control of the lock-up clutch, that is, when a deceleration operation is performed, the throttle rapidly returns (the throttle opening sharply decreases). As a result, there is a problem that the engine torque sharply decreases, the clutch torque capacity relatively increases abruptly, and the lock-up clutch suddenly engages, thereby causing an engagement shock.

[0005] To solve this problem, the gain of the feedback control may be increased. However, in such a case, the gain becomes too large at the time of normal control and becomes unstable.

As disclosed in Japanese Patent Application Laid-Open No. 64-58858, it is conceivable to switch the gain when the throttle opening reaches a certain value. However, when the throttle is returned to a certain value or less, the gain is changed and the occurrence of shock is avoided, but when the throttle opening is returned only to a value just before a certain value, the same as before Thus, there is a problem that a shock occurs.

The present invention has been made in view of such a conventional problem, and a sudden engagement shock due to a rapid return of the throttle is maintained while the gain of the feedback control of the slip amount is maintained at an appropriate value. It is an object of the present invention to provide a control device for a torque converter with a lock-up clutch that can suppress the occurrence.

[0008]

SUMMARY OF THE INVENTION As shown in FIG. 1, the present invention provides a torque converter having an input side connected to an output shaft of an engine and an output side connected to an input shaft of a speed change mechanism. A lock-up clutch for directly connecting the input side and the output side of the converter, an engagement operation mechanism for performing engagement / disengagement of the lock-up clutch and adjusting the engagement force, and controlling the engagement operation mechanism And a slip control means for ensuring a predetermined slip amount between the input side and the output side of the torque converter. And a rate of decrease in the throttle opening detected by the detecting means during the execution of the slip control of the lock-up clutch. When a predetermined value or more is obtained, the slip control by the slip control means is stopped, and the sudden release control means for controlling the engagement operation means to rapidly release the lock-up clutch is provided. Is solved.

[0009]

In the device of the present invention, the return speed (decrease rate) of the throttle opening is monitored during the slip control of the lock-up clutch, and when the value becomes equal to or more than a predetermined value,
The lock-up clutch is suddenly released. Therefore, the sudden engagement of the lock-up clutch due to the sudden decrease of the throttle opening is prevented without changing the gain of the feedback control, and the occurrence of a shock due to the sudden engagement of the clutch is avoided.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a skeleton diagram of a vehicle power transmission device to which an embodiment of the present invention is applied. In the figure,
Reference numeral 10 denotes an engine, 12 denotes a torque converter with a lock-up clutch, and 14 denotes an automatic transmission (transmission mechanism).

The power of the engine 10 is supplied to an automatic transmission 14 via a torque converter 12 with a lock-up clutch.
And transmitted from the output shaft of the automatic transmission 14 to the drive wheels via a differential gear device and the like (not shown).

The torque converter 12 includes a pump impeller 18 directly connected to an output shaft 16 of the engine 10, and a turbine liner 22 fixed to an input shaft 20 of the automatic transmission 14.
, A stator 28 fixed to the housing 26 via a one-way clutch 24, and a lock-up clutch 32 connected to the input shaft 20 via a damper 30.

The torque converter 12 includes an engagement-side oil chamber 35 for introducing the engagement oil pressure of the lock-up clutch 32 and a release-side oil chamber 33 for introducing the release oil pressure. When the oil pressure in the release-side oil chamber 33 is increased, the lock-up clutch 32 is disengaged,
Torque is transmitted from the input side to the output side at an amplification factor corresponding to the input / output rotation speed ratio of the torque converter 12. When the oil pressure in the engagement side oil chamber 35 is higher than that in the release side oil chamber 33, the lock-up clutch 32 is engaged, and the input side and the output side of the torque converter 12, that is, the output shaft 16 of the engine are connected. The input shaft 20 of the automatic transmission is directly connected.

The automatic transmission 14 has three sets of planetary gear units 3.
4, 36, 38, the aforementioned input shaft 20, an output gear 39 rotating together with the ring gear of the planetary gear set 38, and a counter shaft (see FIG. 1) for transmitting power between the output gear 39 and a differential gear set (not shown). Output shaft) 40.

Some of the components of the planetary gear units 34, 36, 38 are not only integrally connected to one another, but are also selectively connected to one another by three clutches C0, C1, C2. In addition, some of the components include four brakes B
0, B1, B2, B3, selectively connected to the housing 26, and three more one-way clutches F0, F1, F
2 engage with each other or with the housing 26 depending on the direction of rotation.

Clutches C0, C1, C2 and brake B
0, B1, B2, and B3 are each hydraulically driven, and a plurality of shift speeds are established as shown in FIG. 3 by a combination of engagement and disengagement thereof.

The hydraulic control circuit 44 controls the engagement and disengagement of the shift control hydraulic control circuit for driving the clutch and the brake to switch the shift speed of the automatic transmission 14 and the lock-up clutch 32 of the torque converter 12. Hydraulic control circuit for engagement control (engagement operation mechanism, slip control means)
Are provided.

The shift control hydraulic control circuit includes a first solenoid valve 4.
6 and a second solenoid valve 48, and the clutch and the brake are selectively driven by a combination of their operations to establish any one of the gear positions.

As shown in FIG. 4, the engagement control hydraulic control circuit includes an ON-OFF type third solenoid valve 50 for outputting a switching signal pressure Psw, and a switching valve for switching from the third solenoid valve 50. A clutch switching valve 52 for switching the lock-up clutch 32 between an engaged state and a released state in response to the signal pressure Psw, a linear solenoid valve 54 for generating a signal pressure Psol corresponding to the input drive current Isol, A lock-up control valve 56 for controlling the drive of the lock-up clutch 32 in response to the pressure Psol.

The lock-up control valve 56 adjusts the pressure difference ΔP between the engagement side oil chamber 35 and the release side oil chamber 33 when the lock-up clutch 32 is engaged, and
Adjust the slip amount of the lock-up clutch 3
At the time of the release drive of No. 2, the release speed is set to either normal release or sudden release.

The hydraulic control circuit 44 includes a pump 60, a strainer 58, a first pressure regulating valve 62, a second pressure regulating valve 66, and a third pressure regulating valve 68.

The first pressure regulating valve 62 supplies a first line pressure PL1 which increases according to the throttle opening to a first line oil passage 64.
Generate on top. The second pressure regulating valve 66 regulates the outflow pressure from the first pressure regulating valve 62 in accordance with the throttle opening, thereby generating a second line pressure PL2 corresponding to the engine output on the second line oil passage 67. The third pressure regulating valve 68 is a pressure reducing valve using the first line pressure PL1 as an original pressure, and has a constant line pressure P
Generate L3.

The lock-up control valve 56 is a spool valve controlled by the linear solenoid valve 54,
Ports 76a, 76b, 76c communicating with the connection oil passage 70, the second connection oil passage 72, and the drain oil passage 74, a port 76d to which the second line pressure PL2 is supplied via a check valve 78, and a drain port 76e, a spool 80 moved between an ON position and an OFF position to switch the connection state of each port, a spring 82 for urging the spool 80 to the ON position via a spring seat 81, and a spool 80 The plunger 84 is disposed so as to be in contact with the spool 80 in order to bias the spool 80 to the ON position, and the spool 80 is pressed to the OFF position via the plunger 84 by introducing the hydraulic pressure Poff in the release-side oil chamber 33. An oil chamber 86 that generates a force that generates a force to press the spool 80 to the ON position when the second line pressure PL2 is introduced. And the spool 80 is turned O by the introduction of the signal pressure Psol from the linear solenoid valve 54.
And an oil chamber 90 for generating a force for pressing to the N position. The spool 80 has a first cross-sectional area having the same cross-sectional area.
A land 92, a second land 94, a third land 96, and a fourth land 98 having a smaller sectional area than those are formed.

The linear solenoid valve 54 has an input port through which the third line pressure PL3 is supplied through an orifice 55 and a drain port, and is supplied from the electronic control unit 42 as shown in FIG. When the drive current Isol is below the predetermined lower limit value IsolA, the communication between the input port and the drain port is made, and the downstream side of the orifice 55 is opened to the drain. On the other hand, when the supplied drive current Isol is in a region exceeding the predetermined upper limit value IsolB, the input port and the drain port are shut off to generate the maximum signal pressure Psol downstream of the orifice 55,
This signal pressure Psol is applied to the oil chamber 90 of the lock-up control valve 56.
Introduce to. Further, the supplied drive current Isol is lower than the lower limit value I.
When it is in the region not less than solA and not more than the upper limit value IsolB,
A signal pressure Psol that increases as the current value increases according to the drive current Isol is generated, and the signal pressure Psol is introduced into the oil chamber 90.

For this reason, the drive current Isol is reduced to the lower limit value IsolA.
When it is smaller, the oil chamber 90 is set to the atmospheric pressure, the spool 80 of the lock-up control valve 56 is set to the OFF position, and the ports 76b and 76c and the port 76a and the drain port 76e communicate with each other. At the same time, the connection between the ports 76a and 76d and the connection between the port 76b and the drain port 76e are cut off. When the drive current Isol is larger than the upper limit value IsolB, the spool 8
0 is located at the ON position, and the switching state is reversed. When the drive current Isol is equal to or higher than the lower limit value IsolA and equal to or lower than the upper limit value IsolB, the spool 80 is in an intermediate state between the above-described two operating states according to the magnitude of the drive current Isol.

The clutch switching valve 52 is a spool valve controlled by the third solenoid valve 50, and is a release-side oil chamber 33.
Port 100A communicating with the engagement side oil chamber 35, the engagement side port 100B communicating with the engagement side oil chamber 35, and the second line pressure PL2.
Port 100c to which the oil is supplied and the first connection oil passage 70
And the port 100 communicating with the second connection oil passage 72
d and 100e, a spool 102 slidable between an ON position and an OFF position for switching the connection state of the ports, a spring 104 for urging the spool to the OFF position, and a lower portion of the spool 102. ON by applying the switching signal pressure Psw from the third solenoid valve 50 to the end face
An oil chamber 106 for receiving the switching signal pressure Psw for generating a thrust toward the position.

The third solenoid valve 50 includes an input port to which the third line pressure PL3 is supplied, a drain port, and an oil chamber 106.
Normally closed 3 with output port communicating with
In the port 2 position valve, in the non-excited state (OFF state), the input port is closed, and the drain port and the output port are communicated to set the oil chamber 106 to atmospheric pressure. In the excited state (ON state), the drain port is closed and the input port and the output port are communicated with each other to apply the switching signal pressure Psw to the oil chamber 106.

Therefore, while the third solenoid valve 50 is in the OFF state, the spool 102 of the clutch switching valve 52 is also turned off.
Located at the FF position, communication is established between the release-side port 100a and the input-side port 100c, between the engagement-side port 100b and the port 100e, and between the engagement-side port 100b and the input port 100c. Between the open side port 100a and the port 100d. Also, during the period when the third solenoid valve 50 is in the ON state,
The spool 102 is also positioned at the ON position, and the switching state is reversed.

Therefore, when the third solenoid valve 50 is in the OFF state and the drive current Isol of the linear solenoid valve 54 is lower than the lower limit value IsolA, the second line pressure is reduced to the input port 100c and the open side. The hydraulic oil in the engagement-side oil chamber 35 flows into the release-side oil chamber 33 through the port 100a.
00e, second connection oil passage 72, port 76b, port 76
c, drain oil passage 74, throttle 108, oil cooler 110
Is drained through. Thereby, the mode "I" of FIG.
The lock-up clutch 32 is released as shown in FIG.

At this time, part of the operating oil discharged from the engagement side oil chamber 35 is guided to the orifice 112 and the oil cooler 110 by the bypass oil passage 111 and is drained. On the upstream side of the oil cooler 110, a cooler bypass valve 114 for draining without passing through the oil cooler 110 when the pressure of the hydraulic oil discharged from the engagement side oil chamber 35 exceeds a predetermined value. Is provided.

When the drive current Isol of the linear solenoid valve 54 exceeds the upper limit value IsolB when the third solenoid valve 50 is ON, the second line pressure P
L2 is caused to flow into the engagement-side oil chamber 35 through the input port 100c and the engagement-side port 100d, and at the same time, is released through the port 76d, the port 76a, the first connection oil passage 70, the port 100d, and the release-side port 100a. Oil chamber 3
3 is also allowed to flow. From this, the pressure difference ΔP between the engagement side oil chamber 35 and the release side oil chamber 33 (= Pon
−Poff) becomes zero, and the lock-up clutch 32 is released as shown in the mode “V” in FIG.

At this time, a part of the operating oil in the engagement side oil chamber 35 is supplied to the orifice 11 by the bypass oil passage 111.
2 and the oil cooler 110 to be drained.

When the drive current Isol of the linear solenoid valve 54 exceeds the upper limit value IsolB when the third solenoid valve 50 is OFF, the second line pressure PL2 is released from the input port 100c. The hydraulic oil in the engagement-side oil chamber 35 flows into the release-side oil chamber 33 through the side port 100a, and the engagement-side port 100b, the port 100e, the second connection oil passage 72, the port 76b, and the drain port 76e. Through to the drain. In this case, the hydraulic oil in the engagement side oil chamber 35 flows out to the drain without passing through the oil cooler 110, so that the lock-up clutch 32 is rapidly released as shown in the mode "II" in FIG. Is done.

As described above, the two modes for releasing the lock-up clutch 32 are two modes for normal release ("I" and "V") and one mode for sudden release ("II"). Exists.

In this embodiment, the mode "I" is selected at the time of normal release, and the mode "V" is selected by the third solenoid valve 50 or the clutch switching valve 5.
2, or when failure of the linear solenoid valve 54 or the lock-up control valve 56 makes it impossible to set the mode to "I".

In the rapid release mode "II", for example, when it is determined by the command of the electronic control unit 42 that the vehicle is to be suddenly braked, or to be braked on a low friction road surface, or when the slip control is being executed. Is executed when the throttle is rapidly returned, that is, when the rate of decrease of the throttle opening is equal to or more than a predetermined value. This will be described later.

On the other hand, when the third solenoid valve 50 is in the ON state and the drive current Isol of the linear solenoid valve 54 is lower than the lower limit value IsolA, the second line pressure PL2 is set to The hydraulic oil in the release-side oil chamber 33 flows into the engagement-side oil chamber 35 through the mating-side port 100b.
00d, is discharged to the drain through the first connection oil passage 70, the port 76a, and the drain port 76e. Thereby, the lock-up clutch 32 is engaged as shown in the mode “III” of FIG.

When the third solenoid valve 50 is ON and the drive current Isol of the linear solenoid valve 54 is higher than the lower limit IsolA and lower than the upper limit IsolB, the second line pressure PL2 Is made to flow into the engagement side oil chamber 35 through the port 100c and the engagement side port 100b. On the other hand, the drive current Iso of the linear solenoid valve 54
l, the amount of hydraulic oil in the release-side oil chamber 33 discharged through the release-side port 100a, the port 100d, the first connection oil passage 70, the port 76a, and the drain port 76e;
The second line pressure PL2 is equal to the port 76d, the port 76a, the first connection oil passage 70, the port 100d, and the release port 100.
a, the pressure difference ΔP between the two oil chambers is adjusted, and
As shown in mode “IV” in FIG. 6, slip control of lock-up clutch 32 is performed.

The slip control mode "IV" is used to smoothly engage the lock-up clutch 32 during acceleration of the vehicle or to absorb periodic torque fluctuations of the engine 10 during low-speed operation of the vehicle.
The mode to be selected and executed. In this mode "I
In "V", the relationship between the drive current Isol input to the linear solenoid valve 54 and the signal pressure Psol has a linear relationship as shown in FIG.

The third solenoid valve 50 as described above is turned on.
Even while the lock-up clutch 32 is engaged or slipping, the operating oil in the engagement-side oil chamber 35 is guided to the oil cooler 110 by the bypass oil passage 111 at a rate corresponding to the orifice 112. Cooled.

Next, returning to FIG. 2, the electronic control unit 42 will be described.

The electronic control unit 42 includes a CPU 182, an RO
M184, a RAM 186, and a microcomputer including an interface (not shown) and the like.
The microcomputer includes a throttle sensor 188 for detecting an opening of a throttle valve provided in an intake pipe of the engine 10, an engine speed sensor 190 for detecting a rotation speed of the engine 10, and a rotation of the input shaft 20 of the automatic transmission 14. An input shaft rotation sensor 192 for detecting the speed, a counter shaft rotation sensor 194 for detecting the rotation speed of the counter shaft 40 of the automatic transmission 12, a shift position sensor 198 for detecting the operation position of the shift lever 196, etc. , Engine rotation speed Ne (rotation speed of the pump impeller of the torque converter, ie, the input side rotation speed of the lock-up clutch), input shaft rotation speed Nin (turbine rotation speed Nt, ie, the output side rotation speed of the lock-up clutch), output shaft Rotation speed Nout, shift lever 196
The signal corresponding to each of the operation positions is input.

The CPU 182 of the electronic control unit 42 processes the input signal according to a program stored in the ROM 184 in advance, and controls the shift control of the automatic transmission 14, the engagement control of the lock-up clutch 32, and the lock-up clutch 32.
The first solenoid valve 46, the second solenoid valve 48, the third solenoid valve 50, and the linear solenoid valve 54 are controlled in order to execute the rapid release control and the like.

In the shift control, a shift diagram corresponding to an actual shift speed is selected from a plurality of types of shift diagrams stored in the ROM 184 in advance, and the traveling state of the vehicle, for example, the throttle opening θth and the throttle opening θth are selected from the shift diagram. The shift speed is determined based on the output shaft rotation speed Nout (equivalent to the vehicle speed), and the first solenoid valve 46 and the second solenoid valve 48 are driven so as to obtain the shift speed. Clutches C0, C1,
The operation of C2 and the brakes B0, B1, B2, and B3 are controlled to establish one of the forward gears.

FIG. 3 shows the shift speeds of the shift lever 196 in each shift range, and the operating states of the solenoid, clutch, brake, and one-way clutch when the shift speed is established. In this table, "〇" and "x" marks in the column of solenoid indicate an excited state and a non-excited state, respectively. Further, the “〇” mark in the column of clutch and brake indicates an engaged state, and the no mark indicates a non-engaged state. Further, the “〇” mark in the column of the one-way clutch indicates that the clutch is in the engaged state at the time of the forward drive, and the blank mark indicates the non-engaged state.

In the engagement control of the lock-up clutch 32, the running state of the vehicle, for example, the vehicle speed (output shaft rotation speed Nou) is determined from the relationship shown in FIG.
t) and the throttle opening θth, the operation range of the lock-up clutch 32 is changed to the release range, the slip range,
Judge from the engagement area.

The relationship between the regions is selected from a plurality of types of relationships stored in advance according to the actual gear position. In FIG. 7, a slip control region is provided on the release region side and on the low throttle opening side with respect to the boundary between the engagement region and the release region. This slip control region is a control region in which the input side and the output side are kept in a slip state for the purpose of absorbing the torque fluctuation of the engine 10 while maintaining the coupling effect of the lock-up clutch 32. The slip state is feedback controlled so as to obtain the amount. Thereby, fuel efficiency can be improved without impairing drivability.

When it is determined that the running state of the vehicle is within the engagement area shown in FIG. 7, the mode "III" in FIG. 6 is executed. That is, the third solenoid valve 50 is excited to turn on the clutch switching valve 52, and at the same time, the drive current Isol to the linear solenoid valve 54 is set to a predetermined minimum drive current value smaller than the above-mentioned lower limit value IsolA. , The lock-up control valve 56 is turned off. Thus, the lock-up clutch 32 is engaged.

When it is determined that the running state of the vehicle is within the slip region shown in FIG. 7, the mode "IV" in FIG.
Is executed. That is, the third solenoid valve 50 is excited to turn on the clutch switching valve 52, and at the same time, the drive current Isol for the linear solenoid valve 54 is adjusted to a value equal to or more than the lower limit value IsolA and equal to or less than the above-mentioned upper limit value IsolB. For example, the steady-state target slip rotation speed NslipT and the actual slip rotation speed Nslip determined from the relationship shown in FIG.
The drive current Isol for the linear solenoid valve 54 is calculated so that the deviation ΔN (Nslip−NslipT) from (= Ne−NT) is eliminated, and the drive current Isol is supplied to the linear solenoid valve 54.

In the above control, if it is determined that the running state of the vehicle has shifted from the release range to the slip range, the third solenoid valve 50 is excited and the clutch switching valve 5 is activated.
2 is turned on, and at the same time, the linear solenoid valve 54
Of the engagement side oil chamber 35 and the release side oil chamber 3 so that the slip control valve 56 has a slip rotation speed Nslip corresponding to the drive current Isol.
The pressure difference ΔP of 3 is adjusted.

In this embodiment, the means for performing the slip control of the lock-up clutch 32 (the linear solenoid valve 54 and the lock-up control valve 56) switches the engagement state of the lock-up clutch 32 (third means). Since the solenoid valve 50 and the clutch switching valve 52) are provided independently of each other, the supply timing of the drive current Isol to the linear solenoid valve 54 can be locked up at least before the switching of the clutch switching valve 52 is completed. It is determined that the spool 80 of the control valve 56 is in the slip control operating position at the time of starting the slip control, so that the fluctuation of the engine rotation speed Ne at the time of starting the slip control is eliminated. ing.

When it is determined that the running state of the vehicle is within the release area shown in FIG. 7, the mode "I" in FIG. 6 is executed. That is, the third solenoid valve 50 is de-energized and the clutch switching valve 52 is turned off. At the same time, the drive current I sol for the linear solenoid valve 54 is set to the minimum drive current value, and the lock-up control valve 56 is turned off. State, and the lock-up clutch 32 is released.

Further, for example, when the throttle opening (according to the present invention) suddenly decreases, or when the speed of change of the gear ratio exceeds a predetermined value, the vehicle is suddenly braked or has low friction road surface. If the braking state in is detected, the mode “II” in FIG. 5 is executed.

That is, the third solenoid valve 50 is de-energized and the clutch switching valve 52 is turned off, and at the same time, the drive current I sol for the linear solenoid valve 54 becomes the upper limit value Iso.
The predetermined maximum drive current value is set to a value greater than 1 B, the lock-up control valve 56 is turned on, and the lock-up clutch 32 is rapidly released.

As described above, the hydraulic control circuit 4 of the present embodiment
In 4, the clutch switching valve 52 is switched in response to the operation of the third solenoid valve 50, whereby the engagement and disengagement of the lockup clutch 32 is switched, and the clutch switching valve is switched by the linear solenoid valve 54. Lock-up clutch 3 with 52 set to the ON position
2, the clutch switching valve 52 is adjusted.
When the lock-up clutch 32 is
Is switched to either the normal release or the quick release.

For this reason, even if the slip control is executed in the slip control area on the release area side of the boundary between the engagement area and the release area shown in FIG. Lock-up clutch 32 at times
Is suddenly released to prevent engine stall. In addition, when the throttle opening is suddenly returned during the execution of the slip control, the lock-up clutch 32 is suddenly released, thereby avoiding a sudden engagement of the lock-up clutch 32 due to a sudden decrease in engine torque. Joint shock is suppressed.

Further, the lock-up control valve 56 is provided with ports 76b, 76c and a drain port 76e for normal release and rapid release of the lock-up clutch 32, so that the lock-up clutch 32 can be rapidly released. Therefore, the hydraulic circuit becomes simpler and less expensive than when a new quick release valve is provided. Therefore, according to the present hydraulic control circuit 44, fuel efficiency can be improved without impairing drivability, and high release response of the lock-up clutch 32 can be obtained without making the hydraulic circuit complicated or expensive.

As a method for obtaining the signal pressure Psol, a linear solenoid valve 54 for generating a signal pressure having a magnitude corresponding to the drive current Isol is provided, but instead of the linear solenoid valve 54, an orifice A two-position operation type solenoid valve may be provided downstream of 55 to control the duty of the solenoid valve to generate the signal pressure Psol.

Next, the contents of control executed in response to a change in the throttle opening while the slip control is being executed will be described with reference to the flowchart of FIG.

Upon entering this control, it is determined in step S1 whether the slip control is currently being executed. If the slip control is not being executed, the processing of this control ends as it is. If the slip control is being performed, the process proceeds to step S2, in which a differential value of the throttle opening θth, that is, a throttle opening change rate (a reduction rate in this case) is obtained. Then, in step S3, a predetermined value α is set based on the map shown in FIG. 10 using the engine speed Ne and the throttle opening θth as parameters.
Is calculated.

Then, in the next step S4, the throttle opening reduction rate Δθth obtained in the previous steps S2 and S3 is compared with the predetermined value α, and if Δθth is smaller than α, step S5 is skipped. This control is ended, and the slip control is continued as it is.

On the other hand, if the throttle opening reduction rate Δθth exceeds the predetermined value α, control is executed to rapidly release the lock-up clutch 32 in step S5.

The predetermined value α in this case is calculated as a function of the engine speed and the throttle opening. For example, as shown in FIG. 11, the same throttle change amount (A1 →
Also in A2), the amount of change in engine torque Te (indicated by “Te dot” in the figure) differs depending on the difference in engine rotation speed. Referring to a graph showing the relationship between the throttle opening θth and the engine torque Te as shown in FIG. 12, the amount of change in the engine torque changes depending on whether the throttle opening θth is equal to or larger than A3. In order to avoid turning off the lock-up clutch (disengagement) as much as possible during driving, the value of α is increased in a place where the variation of the engine torque is small (a region where the throttle opening is large), and a place where the torque variation is large and a shock is likely to occur ( In a region where the throttle opening is small, α is reduced to achieve both suppression of shock and improvement of fuel efficiency.

[0065]

As described above, according to the apparatus of the present invention, when the throttle is suddenly released during the slip control of the lock-up clutch, the lock-up clutch is suddenly released. Therefore, it is possible to prevent the lock-up clutch from suddenly engaging, and to avoid the occurrence of a shock due to the sudden engagement without changing the gain of the feedback control at all, that is, while maintaining the gain at an appropriate value. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a skeleton diagram of a vehicle power transmission device to which an embodiment of the present invention is applied;

FIG. 3 is an operation table of the automatic transmission of the power transmission device.

FIG. 4 is a configuration diagram of a main part of a hydraulic circuit in the same device.

FIG. 5 is an output characteristic diagram of a linear solenoid valve in the hydraulic circuit.

FIG. 6 is a table showing a relationship between a combination of operations of a third solenoid valve and a linear solenoid valve executed in the hydraulic circuit and an engagement state of a lock-up clutch.

FIG. 7 is a diagram showing a relationship between a traveling state of the vehicle and an engagement state of a lock-up clutch stored in the electronic control device of FIG. 2;

FIG. 8 is a diagram showing a relationship for determining a target slip rotation speed in a steady state stored in the electronic control device of FIG. 2;

FIG. 9 shows a part of the lock-up clutch engagement control executed in the electronic control device of FIG. 2, and in particular, stops the slip control in response to a change in the throttle opening to quickly shift the lock-up clutch. Flow chart showing the flow of release control

FIG. 10 is a diagram showing a map for calculating a predetermined value α used for the control in FIG. 9;

FIG. 11 is a diagram showing a relationship between an engine rotation speed and a torque.

FIG. 12 is a diagram showing a relationship between a throttle opening and an engine torque.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Engine 12 ... Torque converter 14 ... Automatic transmission (transmission mechanism) 16 ... Engine output shaft 20 ... Automatic transmission input shaft 32 ... Lockup clutch 33 ... Engagement side oil chamber (engagement operation mechanism) 34 ... Release-side oil chamber (engagement operation mechanism) 44 ... Hydraulic control device (engagement operation mechanism, slip control device) 54 ... Linear solenoid valve (slip control device) 56 ... Lock-up control valve (slip control device)

Claims (1)

(57) [Claims] 1. A torque converter having an input side connected to an output shaft of an engine and an output side connected to an input shaft of a speed change mechanism; a lock-up clutch for directly connecting an input side and an output side of the torque converter; An engagement operation mechanism capable of performing an engagement / disengagement operation of the up-clutch and adjusting an engagement force thereof; and controlling a predetermined slip between the input side and the output side of the torque converter by controlling the engagement operation mechanism. A torque converter with a lock-up clutch, comprising: a slip control unit that secures an amount; a means for detecting a rate of change in the throttle opening of the engine; and a slip control of the lock-up clutch. At this time, when the rate of decrease of the throttle opening detected by the detection means becomes a predetermined value or more, the slip control means And it stops the slip control, the control device of the locking torque converter with a lockup clutch to a sudden release control means for controlling the focus operating means, characterized in that the provided to abruptly release the lock-up clutch.