JPH05180331A - Slippage control device of vehicular direct clutch - Google Patents

Abstract

PURPOSE:To make the fuel cut period of time continue without disturbing a loadless drive feeling while running at a reduced speed by regulating the slippage of a direct clutch so that the actual slip revolution speed of the direct clutch may conform to the target slip revolution speed. CONSTITUTION:Because a slippage NSLP of a lock up clutch 32 is a subtracted value of an engine revolution speed Ne from a turbine revolution NT, the slippage is regulated so that the actual slip revolution speed NSLP conforms to a target slip revolution speed NSLP deg.. The target slip revolution speed NSLP deg. is determined on the basis of the revolution speed difference which is arrived by subtracting a fuel cut return revolution speed NRT from the turbine revolution speed NT. Thus the fuel cut period of time can be continued as long as possible without disturbing the loadless drive feeling while running at a reduced speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip control device for a direct coupling clutch for a vehicle.

[0002]

2. Description of the Related Art A direct coupling clutch for a vehicle is engaged in order to eliminate a rotational loss of a torque converter or a fluid coupling, and is provided in a direct coupling clutch engagement diagram, for example, in order to improve fuel consumption. Slip control is performed when the vehicle is running within the slip range. Further, in order to save the fuel by lengthening the period during which the engine rotation speed is made higher than the fuel cut return rotation speed during decelerating traveling, the direct coupling clutch may be slip controlled. For example, Japanese Patent Laid-Open No. 57-33253
This is the slip control device described in Japanese Patent Laid-Open Publication No. 2003-242242, and is directly connected so that the actual slip rotation speed, which is the difference between the turbine rotation speed and the engine rotation speed, becomes a preset constant value during deceleration of the vehicle. The clutch slip amount is controlled.

[0003]

In the conventional slip control device described above, when the target slip amount is set to be small,
Although the effect of saving the fuel amount becomes large, the negative torque becomes large because the engine speed is kept high, and the feeling of idling during deceleration of the vehicle is impaired. On the contrary, if the target slip amount is set to a large value, a feeling of idling when the vehicle is decelerating will be sufficiently obtained, but the engine speed will drop earlier than the fuel cut return speed and fuel supply will be reduced. Since it is restarted, the fuel saving effect is lost. As described above, it has been a very difficult problem to uniformly set the target slip amount that achieves both the fuel consumption and the feeling of idling during deceleration coasting of the vehicle.

The present invention has been made in view of the above circumstances, and an object of the present invention is to maintain a fuel cut period as long as possible without impairing a feeling of idling during deceleration of a vehicle. It is an object of the present invention to provide a slip control device for a direct coupling clutch for a vehicle that can perform the above.

[0005]

The gist of the present invention for achieving the above object is to connect a pump impeller and a turbine impeller directly, as shown in the gist of the invention of FIG. A fluid transmission having a direct coupling clutch, and when the vehicle speed is reduced, the fuel supply to the engine is cut off when the engine rotation speed exceeds a preset fuel cut rotation speed, and the engine rotation speed is reset to the preset fuel cut speed. In a vehicle having a fuel cut control device that restarts fuel supply when the rotational speed is lower than the rotational speed, a slip control device of the type that slips the direct coupling clutch during deceleration traveling of the vehicle, (a)
Turbine rotation speed detection means for detecting the rotation speed of the turbine impeller, and (b) a target based on a rotation speed difference obtained by subtracting the fuel cut return rotation speed from the turbine rotation speed detected by the turbine rotation speed detection means. Target slip rotation speed determining means for determining the slip rotation speed, and (c) slip amount control means for adjusting the slip amount of the direct coupling clutch so that the actual slip rotation speed of the direct coupling clutch matches the target slip rotation speed. And include.

[0006]

With this configuration, the target slip rotation speed determination means determines the target slip rotation speed based on the rotation speed difference obtained by subtracting the fuel cut return rotation speed from the turbine rotation speed detected by the turbine rotation speed detection means. The slip amount of the direct coupling clutch is adjusted by the slip amount control means so that the actual slip rotational speed of the direct coupling clutch matches the target slip rotational speed.

[0007]

Since the slip amount of the direct coupling clutch is a value obtained by subtracting the engine rotational speed from the turbine rotational speed, the slip rotational speed of the direct coupling clutch is made to match the target slip rotational speed as described above.
In the process in which the turbine rotation speed approaches the fuel cut return rotation speed, the engine rotation speed is maintained at the fuel cut return rotation speed as much as possible. Therefore, when the vehicle is decelerating, the fuel cut period can be maintained as long as possible without impairing the feeling of idling.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing a vehicle power transmission device to which an embodiment of the present invention is applied. In the figure, the power of the engine 10 is transmitted to the drive wheels via a torque converter 12 with a lockup clutch 12, a stepped automatic transmission 14 including three sets of planetary gear units, and a differential gear device (not shown). It has become so.

The torque converter 12 is the engine 1
Pump impeller 18 connected to zero crankshaft 16
And a turbine impeller 22 fixed to the input shaft 20 of the automatic transmission 14 and rotated by receiving oil from the pump impeller 18, and a housing 26 which is a non-rotating member via a one-way clutch 24. Stator wheel 28
And a lock-up clutch 32 connected to the input shaft 20 via a damper 30. When the hydraulic pressure in the disengagement side oil chamber 33 is higher than that in the engagement side oil chamber 35 in the torque converter 12, the lockup clutch 32 is disengaged, so that the input / output rotational speed ratio of the torque converter 12 is reduced. The torque is transmitted at a corresponding amplification factor. However, when the oil pressure in the engagement-side oil chamber 35 is higher than that in the disengagement-side oil chamber 33, the lock-up clutch 32 is engaged, so that the input / output members of the torque converter 12, that is, the crankshaft 16 and the input. The shaft 20 is directly connected.

The automatic transmission 14 includes the input shaft 20 and the output shaft 34, and one of a plurality of forward gear stages and a reverse gear stage is formed by a combination of operations of a plurality of hydraulic friction engagement devices. It is configured as a well-known stepped planetary gear device that is selectively realized. And
A shift control hydraulic control circuit 44 for controlling the gear stage of the automatic transmission 14 and an engagement control hydraulic control circuit 46 for controlling the engagement of the lockup clutch 32 are provided. As is well known, the hydraulic control circuit 44 for shift control includes solenoid No. 1 and solenoid No. 2.
A first solenoid valve 48 and a second solenoid valve 50 that are respectively turned on and off by the first solenoid valve 4
The clutch and the brake are selectively operated by a combination of the operations of the eighth electromagnetic valve 50 and the second electromagnetic valve 50 to establish one of the first to fourth speed gear stages.

Further, the engagement control hydraulic control circuit 46 includes a linear solenoid valve 52 operated by a solenoid No. 3 which is a linear solenoid, a release side position for releasing the lockup clutch 32, and the lockup clutch 32. A switching valve 54 that is switched to an engagement-side position that engages the valve, and a regulator pressure P _cl that is generated according to a throttle valve opening degree by a clutch pressure regulating valve (not shown) in the shift control hydraulic control circuit 44. It is provided with a slip control valve 56 that uses the original pressure. The linear solenoid valve 52 uses a constant modulator pressure P _modu generated in the shift control hydraulic control circuit 44 as a _source pressure, and a drive current I _sol from the electronic control unit (ECT) 42.
The output pressure P _lin of a magnitude corresponding to the magnitude of is continuously generated, and the output pressure P _{lin is applied} to the switching valve 54 and the slip control valve 56.

The switching valve 54 includes a spring 58 for urging a spool valve element (not shown) toward a release side position,
The first port 60 to which the regulator pressure P _cl is supplied
And a second port 62 to which the output pressure of the slip control valve 56 is supplied and a third port 64 connected to the release side oil chamber 33.
And a fourth port 66 connected to the engagement side oil chamber 35, and a fifth port 68 connected to the drain. When the output pressure P _lin of the linear solenoid valve 52 supplied to the switching valve 54 falls below a predetermined constant value, the spool valve element is positioned at the release side position according to the urging force of the spring 58. , The second port 62 is closed, and the first port 60 and the third port 64 and the fourth port 66 and the fifth port 68 are made to communicate with each other. Therefore, when the output pressure P _lin of the linear solenoid valve 52 acting on the spool valve element of the switching valve 54 falls below a predetermined constant value, the spool valve element of the switching valve 54 is released according to the urging force of the spring 58. The hydraulic pressure P _off in the disengagement side oil chamber 33 is set to the regulator pressure P _cl, and at the same time, the hydraulic pressure P _on in the engagement side oil chamber 35 is set to the atmospheric pressure so that the lock-up clutch 32 is moved. To be released. However, when the output pressure P _lin of the linear solenoid valve 52 acting on the spool valve element of the switching valve 54 exceeds a predetermined constant value, the spool valve element of the switching valve 54 resists the biasing force of the spring 58. To the engagement side position to close the fifth port 68 and to connect the first port 60 and the fourth port 66, and the second port 62 and the third port 64, respectively. Therefore, the hydraulic pressure P _on in the engagement side oil chamber 35 is set to the regulator pressure P _cl, and at the same time, the hydraulic pressure P _off in the disengagement side oil chamber 33 is pressure controlled by the slip control valve 56 and the lockup clutch 32.
Is slip controlled or released.

The slip control valve 56 has a spring 70 for urging a spool valve element (not shown) toward the output pressure increasing side. The oil pressure P _on in the engagement side oil chamber 35 is applied to the spool valve element in order to generate a thrust force toward the output pressure increasing side, and at the same time, in order to generate a thrust force toward the output pressure decreasing side. The oil pressure P _off in the release side oil chamber 33 and the output pressure P _{lin of the} linear solenoid valve 52
Are operated respectively. Therefore, in the slip control valve 56, the differential pressure ΔP (= P _on −P _off ) corresponding to the slip amount is determined by the linear solenoid valve 5 as shown in Formula 1.
It operates so as to have a value corresponding to the output pressure P _{lin of} 2.
Here, in Formula 1, F is the urging force of the spring 70,
A ₁ is the pressure receiving area of the oil pressure P _on in the spool valve, A ₂
(However, A ₁ = A ₂ ) is the pressure receiving area of the hydraulic pressure P _off , and A ₃ is the pressure receiving area of the output pressure P _lin .

[0014]

[Equation 1]

Therefore, in the engagement control hydraulic control circuit 46 configured as described above, the hydraulic pressure P _on in the engagement side oil chamber 35 and the hydraulic pressure P _off in the release side oil chamber 33 are as shown in FIG.
As shown in, the output pressure P _lin of the linear solenoid valve 52 is
The linear solenoid valve 52
The switching control of the switching valve 54 and the slip control of the lockup clutch 32 after the switching valve 54 is switched to the engagement position can be performed by the output pressure P _lin of the switching valve 54.

The electronic control unit 42 includes a CPU 82 and a ROM.
A so-called microcomputer including 84, RAM 86, an interface (not shown), and the like.
A throttle sensor 88 for detecting a throttle valve opening provided in an intake pipe 80 of the engine 10, an engine rotation speed sensor 90 for detecting a rotation speed of the engine 10, and an input for detecting a rotation speed of an input shaft 20 of the automatic transmission 14. The shaft rotation sensor 92, the output shaft rotation sensor 94 that detects the rotation speed of the output shaft 34 of the automatic transmission 14, and the operating position of the shift lever 96, that is, any of the L, S, D, N, R, and P ranges are detected. From the operation position sensor 98 for controlling the throttle valve opening θ _th , engine speed N
_e (pump impeller rotation speed N _P ), input shaft rotation speed N _in (turbine impeller rotation speed N _T ), output shaft rotation speed N _out , shift lever 96 operation position P A signal representing _s is supplied to each. The CPU 82 of the electronic control unit 42 is a RAM
The first solenoid valve 48 for processing the input signal according to the program stored in advance in the ROM 84 while utilizing the temporary storage function of 86, and executing the shift control of the automatic transmission 14 and the engagement control of the lockup clutch 32, Second solenoid valve 5
0 and the linear solenoid valve 52 are controlled respectively.
In the above shift control, a shift diagram corresponding to an actual shift gear is selected from a plurality of shift diagrams stored in the ROM 84 in advance, and the running state of the vehicle, for example, the throttle valve opening θ _th is selected from the shift diagram. And the vehicle speed SPD calculated from the output shaft rotation speed N _out, the shift gear is determined, and the first solenoid valve 48 is provided so that the shift gear is obtained.
By driving the second electromagnetic valve 50, the automatic transmission 1
The operation of the clutch and brake of No. 4 is controlled to move forward 4
One of the gear stages is established.

In the vehicle of this embodiment, the air-fuel ratio of the air-fuel mixture sucked into the engine 10 is controlled by the air-fuel ratio control device 100. This air-fuel ratio control device 1
00 is supplied with a signal representing the intake air amount Q from the intake air amount sensor 102 provided in the intake pipe 80, and represents the throttle valve opening degree θ _th from the throttle sensor 88 provided in the intake pipe 80. The engine rotation speed sensor 90 supplies a signal representing the engine rotation speed N _e . Further, a signal S _O2 representing the concentration of oxygen contained in the exhaust gas is supplied to the air-fuel ratio control device 100 from an oxygen sensor 104 provided in an exhaust pipe (not shown).

The air-fuel ratio control device 100 has a CPU 106, a ROM 108, and a RAM 1 like the electronic control device 42.
A microcomputer including a CPU 10
6, while determining the basic injection time T _p based on the actual engine speed N _e and the intake air quantity Q from pre-stored in the ROM108 relationship, the basic injection time T _p in accordance with a signal from the oxygen sensor 104 The fuel is injected from the fuel injection valve 112 into the intake pipe 80 for the corrected injection time T _F. Further, the air-fuel ratio control device 1
00 determines coasting of the vehicle, that is, deceleration traveling, based on the throttle valve opening degree θ _th , and when the vehicle is decelerating traveling, the engine rotation speed N _e is set to a preset fuel cut rotation speed N _CUT . In the higher state, in order to save the fuel and reduce the harmful components of the exhaust gas, the fuel supply by the fuel injection valve 112 is shut off, while the engine rotation speed N _e further decreases and the preset fuel cut return rotation is performed. _{Below the} speed N _RT , the above fuel injection valve 1
12 to restart fuel supply to prevent engine 10 from stalling. In this respect, the air-fuel ratio control device 10
0 also functions as a fuel cut control device.

The main part of the engagement control operation of the lockup clutch 32 by the electronic control unit 42 will be described in detail below with reference to the flow charts of FIGS. 4, 5 and 6.

FIG. 4 is a general flow chart. First, in a step (not shown), the throttle valve opening θ _th , which is the state quantity of the vehicle running based on the input signal, the engine rotation speed _Ne , the input shaft rotation speed N _in , the output shaft rotation speed N _out , the air-fuel ratio The feedback correction signal F _AF or the like is read. Next, at step SG1, it is judged if the throttle valve opening θ _th is the idle opening (substantially fully closed position). If the determination in step SG1 is affirmative, whether or not the rotational speed N _t (= N _in ) of the turbine impeller 22 is equal to or higher than a preset determination reference value C _N in step SG2. To be judged. This determination reference value C _N is for preventing slip control during deceleration traveling in step SG3 from being performed in a state where fuel cut is not performed, and is substantially the same value as the fuel cut rotation speed N _cut , for example. Alternatively, a value slightly larger than that is set.

When the accelerator pedal is depressed and the throttle valve opening degree θ _th is not the idle opening degree (substantially fully closed position), the determination at step SG1 is denied.
Another control of step SG4 is executed. Further, when the rotation speed N _T of the turbine impeller 22 is lower than the determination reference value C _N , the determination in the above step SG2 is denied, so
Another control of step SG4 is executed. The other control is control of the lock-up clutch 32 during traveling of the vehicle in which the accelerator pedal is depressed, and, for example, of the release area, the slip area, and the engagement area stored in the ROM 84 shown in FIG. 5 in advance. Output shaft rotation speed (vehicle speed)
It is determined which region the vehicle state represented by N _out and the throttle valve opening θ _th belongs to. If it belongs to the disengagement region, the lockup clutch 32 is disengaged and belongs to the engagement region. In this case, the lockup clutch 32 is engaged, and when it belongs to the slip region, slip control of the lockup clutch 32 is executed. In this slip control during acceleration, the linear solenoid valve is arranged so that the actual slip rotation speed matches the target slip rotation speed that is determined so as to preferably absorb the torque fluctuation of the engine 10 and improve the fuel economy as much as possible. 52 is driven.

However, when the throttle valve opening θ _th is the idle opening when the vehicle is decelerating and the turbine impeller rotation speed N _{T at} this time is the judgment reference value C _N or more, the above step SG1 is performed. Since the determinations of SG and SG2 are respectively affirmed, the slip control routine at the time of deceleration traveling shown in FIG. 6 is executed in step SG3. First, in step SS1 of FIG. 6, the target slip rotation speed N _slp ° is calculated by the target slip rotation speed calculation routine shown in FIG. 7, for example.

In step SM1 of FIG. 7, the actual turbine impeller rotation speed N _T , the fuel cut return rotation speed N _RT , from the relationship stored in advance in the ROM 84 shown in Equation 2,
And the target slip rotation speed N based on the margin value N _C
A provisional value D of _slp ° is calculated. As shown in FIG. 8, this margin value N _C is a small value for surely increasing the engine rotation speed N _e from the fuel cut return rotation speed N _RT , for example, a value of about 10 rpm. The slip rotation speed N _slp ° is substantially determined on the basis of the rotation speed difference between the turbine impeller rotation speed N _T and the fuel cut return rotation speed N _RT , as is apparent from the equation (2).

[0024]

[Equation 2]

In the subsequent steps SM2 to SM5, the provisional value D obtained in step SM1 is set to the upper limit value C ₁
And the lower limit value C ₂ within the range. That is, in step SM2, it is determined whether or not the provisional value D is larger than the upper limit value C ₁ , and if it is larger, step S
In M3, the content of the provisional value D is set as the upper limit value C ₁ . In step SM4, it is determined whether the provisional value D is smaller than the lower limit value C ₂ , and if it is smaller, step S
In M5, the content of the provisional value D is set to the lower limit value C ₂ .

As shown in FIG. 8, when the turbine rotational speed N _T approaches the fuel cut return rotational speed N _RT as the turbine rotational speed N _T decreases during deceleration, the target slip rotational speed N _T
The target slip rotation speed N _slp ° is prevented from becoming smaller than the lower limit value C ₂ because _slp ° becomes zero and inconvenience occurs. This lower limit value C ₂ is set to the same value as the target slip rotation speed N _slp ° at the time of setting the emphasis on fuel consumption shown by the alternate long and short dash line in FIG. 9 showing the time chart of the conventional slip control device. Cage,
The same fuel efficiency effect as at that time can be obtained. Further, the target slip rotation speed N _slp ° increases at high vehicle speeds when the turbine impeller rotation speed N _T is high,
This is also not necessary to be larger than the target slip rotational speed N _slp ° when the air run feeling oriented setting shown in two-dot chain line in FIG. 9, the upper limit value C ₁ when the setting of the empty run feeling emphasized The target slip rotation speed N _slp ° is set to the same value. However, no matter how large the target slip rotation speed N _slp ° becomes, the maximum slip amount is limited by the characteristics of the torque converter 12, so the upper limit value C ₁ may not be set.

After steps SM2 to SM5, in step SM6, the provisional value D is set as the target slip rotation speed N _slp ° in the slip control of the lockup clutch 32 during decelerating traveling.

As described above, the target slip rotation speed N
_{When slp} ° is determined, in step SS2 of FIG. 6, the actual slip rotation speed N _slp is stored in advance in Equation 3
Calculated from Further, in the subsequent step SS3, the control deviation ΔN is calculated from Equation 4 stored in advance.

[0029]

[Equation 3]

[0030]

[Equation 4]

Next, in step SS4, the driving current I _sol of the linear solenoid valve 52 is stored in advance in Equation 5
It is calculated based on the above-mentioned control deviation ΔN from the feedback control formula shown in. The drive current I _sol is output to the linear solenoid valve 52 in step SS5. Therefore, by repeatedly executing the above steps, during deceleration of the vehicle, the slip amount of the lockup clutch 32 becomes the target slip rotation speed N _slp ° as shown in the time chart of FIG. Controlled.

[0032]

[Equation 5]

That is, the target slip rotation speed N _slp ° is determined by the turbine impeller rotation speed N
_{Since the} fuel cut return rotational speed N _RT and the margin value N _C are subtracted from _T and the values are limited within the range of the upper limit value C ₁ and the lower limit value C ₂ ,
In the initial state of the slip control in which the deceleration running of the vehicle is started, the engine rotation speed N _e decreases while maintaining the rotation difference lower than the turbine impeller rotation speed N _T by the upper limit value C ₁ . In this state, the engine rotation speed N _e is higher than the fuel cut rotation speed N _CUT , so the fuel cut by the air-fuel ratio control device 100 is started. Next, in the process in which the engine rotation speed N _e approaches the fuel cut return rotation speed N _RT , it is maintained at a state higher than the fuel cut return rotation speed N _RT by a margin value N _C for a predetermined period, and the turbine impeller rotation speed N N is maintained. _{When T} approaches the fuel cut return rotation speed N _RT , the engine rotation speed N _e is set to a value lower than the fuel cut return rotation speed N _RT by the lower limit value C ₂ , and such engine rotation speed N _e returns to the fuel cut return. When the rotation speed falls below the N _RT , the fuel cut by the air-fuel ratio control device 100 is stopped and the fuel supply from the fuel injection valve 112 is restarted.

Incidentally, according to the control operation of the conventional slip control device, as shown in FIG.
The slip amount of was controlled to a constant target value. That is, when the target slip rotation speed N _slp ° is set small with emphasis on increasing the fuel cut effect, the engine rotation speed N as shown by the one-dot chain line in FIG.
_e changes. In this case, the engine rotation speed N _e is raised relatively high along the turbine impeller rotation speed N _T , so that a relatively large negative torque acts on the vehicle during deceleration to enhance the engine braking feeling. Therefore, the vehicle feels uncomfortable and gives a feeling of strangeness. Further, when the target slip rotation speed N _slp ° is set to be large with an emphasis on the idling feeling of the vehicle, the engine rotation speed N _e changes as shown by the chain double-dashed line in FIG. 9. In this case, the engine rotation speed N _e falls below the fuel cut return rotation speed N _RT relatively early, so that a sufficient fuel saving effect cannot be obtained.

As described above, according to this embodiment, based on the rotational speed difference obtained by subtracting the fuel cut return rotational speed N _RT from the turbine rotational speed N _T in step SS1 corresponding to the target slip rotational speed determination means. The target slip rotation speed N _slp ° is substantially determined, and by steps SS2 to SS5 corresponding to the slip amount control means,
Actual slip rotation speed N of the lockup clutch 32
_The slip amount is adjusted so that _slp matches the target slip rotation speed N _slp °. Lockup clutch 3
The slip amount N _{slp of} 2 is a value obtained by subtracting the engine rotation speed N _e from the turbine rotation speed N _T , as shown in Formula 3, and thus the actual slip rotation speed N as described above.
By matching _slp with the target slip rotation speed N _slp °, the engine rotation speed N _e is always maintained at a value slightly higher than the fuel cut return rotation speed N _RT . Therefore, when the vehicle is decelerating, the fuel cut period can be maintained as long as possible without impairing the feeling of idling.

Further, the fuel cut return rotational speed N _RT
May be changed in accordance with a change in the cooling water temperature of the engine 10 and a load state of the engine 10 at the time of idling related to the operation of the air conditioner. According to the present embodiment, the fuel cut return rotational speed N is changed. No matter how the _RT changes, there is an advantage that it can be dealt with by a common control formula.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other modes.

For example, although the torque converter 12 having the lockup clutch 32 has been described in the above embodiment, a fluid coupling having the lockup clutch 32 may be used.

Further, the automatic transmission 14 of the above-mentioned embodiment is
Although it is composed of the planetary gear type stepped transmission, it may be a belt type continuously variable transmission provided with a pair of variable pulleys having variable effective diameters and a transmission belt wound around them.

The above description is merely one embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of drawings]

FIG. 1 is a diagram showing a summary of the present invention.

FIG. 2 is a diagram showing a power transmission device of a vehicle including a slip control device according to an embodiment of the present invention.

3 is a drive current I _sol of a linear solenoid valve and a hydraulic pressure P in an engagement side oil chamber in the slip control device shown in FIG.
is a diagram showing the relationship between the _on and release-side oil chamber of the oil pressure P _off.

FIG. 4 is a general flowchart for explaining a main part of control operation of the electronic control device of FIG.

5 is a diagram showing relationships used in the flowchart of FIG.

FIG. 6 is a flowchart illustrating a slip control routine during deceleration traveling in FIG.

FIG. 7 is a flowchart illustrating a target slip rotation speed calculation routine of FIG.

8 is a time chart illustrating a slip state of the lockup clutch obtained by the control illustrated in FIG.

FIG. 9 is a diagram corresponding to FIG. 8 in the conventional slip control device.

[Explanation of symbols]

12 torque converter (fluid transmission device) 32 lockup clutch (direct coupling clutch) 42 electronic control device 92 input shaft rotation speed sensor (turbine rotation speed detection means) 100 air-fuel ratio control device (fuel cut control device) Step SS1 target slip rotation speed Determination means Steps SS2 to SS5 Slip amount control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinya Nakamura 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A fluid transmission device having a direct coupling clutch for directly coupling between a pump impeller and a turbine impeller, and to the engine when the engine rotation speed exceeds a preset fuel cut rotation speed during deceleration travel of the vehicle. In a vehicle having a fuel cut control device that cuts off the fuel supply and restarts the fuel supply when the engine rotation speed falls below a preset fuel cut return rotation speed, the direct coupling clutch is applied during deceleration traveling of the vehicle. A slip control device for slipping, comprising turbine rotation speed detection means for detecting the rotation speed of the turbine impeller, and subtracting the fuel cut return rotation speed from the turbine rotation speed detected by the turbine rotation speed detection means. The target slip rotation speed based on the difference in rotation speed And a slip amount control unit that adjusts the slip amount of the direct coupling clutch so that the actual slip rotational speed of the direct coupling clutch matches the target slip rotational speed. Slip control device for direct coupling clutch for vehicles.