JPH05312263A - Controller for slip of lock-up clutch for vehicle - Google Patents

Abstract

PURPOSE:To prevent the rotational speed of an engine from abrupt increase due to a change in travelling resistance by increasing desired slip rotational speed according to a difference between actually detected throttle valve opening and valve opening by a reference throttle valve opening determining means for maintaining vehicle speed during travelling on a flat road surface. CONSTITUTION:When the travelling resistance of a vehicle travelling with constant speed is increased, a throttle valve opening is increased by an electronic controller 200 for cruise control to avoid the reduction of vehicle speed. At the same time, desired slip rotational speed is increased according to a opening difference thetai-thetaa between a reference throttle valve opening thetaa for maintaining the vehicle speed in travelling on a flat road surface and an actually increased throttle valve opening thetai. Thus, a slip amount of a lock-up clutch 32 is increased since the increasing operation of the throttle valve opening, so that the output torque is increased as the rotational speed of an engine is continuously increased to increase the vehicle speed. Thus, the rotational speed of the engine is prevented from abrupt increase.

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 vehicle lock-up clutch, and more particularly to a technique for preventing deterioration of drivability due to frequent engagement and disengagement of the lock-up clutch.

[0002]

2. Description of the Related Art In a vehicle equipped with a hydraulic power transmission device such as a torque converter with a lockup clutch or a fluid coupling with a lockup clutch, the vehicle is driven when it enters a predetermined slip range. In order to improve the fuel consumption of the engine and to absorb the periodic torque fluctuation of the engine, there is proposed a control device that slips so that the rotational speed difference of the lockup clutch is maintained at a predetermined target value. For example, it is the hydraulic control device described in Japanese Patent Laid-Open No. 1-98759. But,
According to such a slip control device, when the acceleration operation is performed in the state where the throttle valve opening is small, the torque amplifying action of the torque converter cannot be effectively obtained, and the acceleration performance may not be sufficiently obtained. .. On the other hand, a slip control device has been proposed in which the target slip amount is changed to an increasing side when the rate of change of the throttle valve opening is equal to or greater than a set value. For example, the device described in Japanese Patent Laid-Open No. 2-256964 is such a device. According to this, the torque amplifying action of the torque converter can be effectively obtained during the acceleration operation, so that sufficient acceleration can be obtained and the torque converter slips during the steady operation in which the rate of change of the throttle valve opening is smaller than the set value. It is possible to suitably suppress the decrease in fuel consumption due to

[0003]

By the way, according to the slip control device as described above, in a traveling state at a relatively constant speed in which the change rate of the throttle valve opening is small, the vehicle travels on an uphill road, for example. When the vehicle state deviates from the slip area of the lockup clutch to the release area due to the increased resistance, the lockup clutch is released and the engine speed suddenly increases against the driver's intention. There was an inconvenience. Further, such inconvenience is remarkable in a vehicle equipped with a cruise control device that maintains a constant vehicle speed. That is, in a vehicle that is maintained at a constant vehicle speed by the cruise control device and is slip controlled so that the lock-up clutch reaches the target slip amount because the vehicle state is within the slip range, for example, when traveling on an uphill road. When the vehicle speed decreases due to an increase in running resistance, the cruise control device increases in order to maintain the vehicle speed constant, and the engine output torque does not change while the engine speed does not change due to the increase in the throttle valve opening. The vehicle speed increases due to the increase in the output torque, but the vehicle speed does not increase when the engine speed does not change, and the throttle valve opens widely, so the vehicle condition is the slip area of the lockup clutch. To the release range from the engine speed Suddenly increases and of giving an uncomfortable feeling to the driver.

The present invention has been made in view of the above circumstances, and an object of the present invention is to lock a vehicle in which the engine speed does not suddenly increase due to a change in running resistance while the vehicle is running. An object is to provide a slip control device for an up clutch.

[0005]

In order to achieve the above object, the gist of the present invention is that the engagement side oil chamber and the disengagement side are as shown in FIG. 1 for explaining the gist of the invention. In a hydraulic transmission with a lockup clutch for a vehicle in which a lockup clutch is operated according to a pressure difference in an oil chamber, the slip amount of the lockup clutch is controlled to a target slip rotation speed by controlling the pressure difference. (A) vehicle speed detecting means for detecting vehicle speed; (b) throttle valve opening detecting means for detecting throttle valve opening; and (c) pre-stored load. Based on the vehicle speed detected by the vehicle speed detection means from the road diagram, a reference throttle valve opening for determining a reference throttle valve opening for maintaining the vehicle speed when traveling on a flat road surface Deciding means, (d) according to the opening difference between the actual throttle valve opening detected by the throttle valve opening detecting means and the reference throttle valve opening determined by the reference throttle valve opening determining means. , Target slip rotation speed changing means for increasing the target slip rotation speed.

[0006]

In this way, according to the opening difference between the actual throttle valve opening detected by the throttle valve opening detecting means and the reference throttle valve opening determined by the reference throttle valve opening determining means. Then, the target slip rotation speed changing means increases the target slip rotation speed.

[0007]

As a result, when the running resistance increases due to a vehicle traveling at a constant speed traveling on an uphill road,
The throttle valve opening is increased by the driver or the cruise control device in order to avoid a decrease in vehicle speed, but at the same time, the reference throttle valve opening and its increase for maintaining the vehicle speed at that time when traveling on a flat road surface. Since the target slip rotation speed is increased in accordance with the opening difference from the throttle valve opening thus set, the slip amount of the lockup clutch is increased from the time of increasing the throttle valve opening. Is continuously increased, the output torque is increased and the vehicle speed is increased. Therefore, even if the vehicle state deviates from the slip region of the lockup clutch to the release region, the engine rotation speed does not suddenly increase, and a feeling of strangeness does not occur.

[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 skeleton view of 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 has three coaxially arranged parts.
Set of single pinion type planetary gear units 34, 36, 38
And an input shaft 20, an output gear 39 that rotates together with a ring gear of the planetary gear device 38, and a counter shaft (output shaft) 40 that transmits power between the differential gear device. Some of the components of the planetary gear units 34, 36 and 38 are not only integrally connected to each other, but also selectively connected to each other by three clutches C ₀ , C ₁ and C ₂ . Further, the planetary gear units 34, 36, 3
Some of the eight components are four brakes B ₀ , B ₁ , B
₂ and B ₃ are selectively connected to the housing 26, and further, some of the components are engaged with each other or with the housing 26 by their rotational directions by three one-way clutches F ₀ , F ₁ and F ₂ . It is supposed to be done.

The clutches C ₀ , C ₁ and C ₂ and the brakes B ₀ , B ₁ , B ₂ and B ₃ are provided with, for example, a multi-plate type clutch or one band or two bands whose winding directions are opposite to each other. It is composed of band brakes and the like, and is operated by hydraulic actuators respectively. As shown in FIG. 3, the operation of these hydraulic actuators is controlled by the electronic control unit 42 for shifting, which will be described later. The gear ratio I (= rotational speed of the input shaft 20 /
It is possible to obtain four forward gears and one reverse gear having different rotational speeds of the counter shaft 40. In Fig. 3, "1s
"t", "2nd", "3rd", "O / D (overdrive)"
Represents the forward first speed gear, the second speed gear, the third speed gear, and the fourth speed gear, respectively, and the above gear ratio changes from the first variable gear speed to the fourth speed gear speed. It becomes smaller as it goes. Note that FIG. 3 will be described in detail later. Further, the torque converter 12 and the automatic transmission 14 described above.
Is symmetrical with respect to the axis, the lower side of the rotation axis of the input shaft 20 and the upper side of the rotation axis of the counter shaft 40 are omitted in FIG.

The hydraulic control circuit 44 includes a shift control hydraulic control circuit for controlling the gear stage of the automatic transmission 14 and an engagement control hydraulic control for controlling the engagement of the lockup clutch 32. And a control circuit. As is well known, the hydraulic control circuit for gear shift control includes a first solenoid valve 46 and a second solenoid valve 48 that are turned on and off by solenoid No. 1 and solenoid No. 2, respectively. Valve 46 and second solenoid valve 4
As shown in FIG. 3, the clutch and the brake are selectively operated by a combination of the operations of No. 8 to establish any one of the first to fourth speed gear stages.

The engagement control hydraulic control circuit is, for example, as shown in FIG. 4, a third electromagnetic valve 50 which is turned on and off by a switching electromagnetic solenoid 49 to generate a switching signal pressure P _sw . According to the switching signal pressure P _sw , a clutch switching valve 52 that is switched between a disengagement side position where the lockup clutch 32 is disengaged and an engagement side position where the lockup clutch 32 is engaged, and an electronic shift control device. A linear solenoid valve 54 that generates a slip control signal pressure P _lin corresponding to the drive current I _sol supplied from 42, and an engagement side oil chamber 35 according to a slip control signal pressure P _lin output from the linear solenoid valve 54. And a slip control valve 5 for adjusting the pressure difference ΔP between the release side oil chamber 33 and controlling the slip amount of the lockup clutch 32.
6 and 6.

The hydraulic control circuit 44 is provided with a pump 60 for sucking and pumping hydraulic oil that has flowed back to a tank (not shown) through a strainer 58, and the hydraulic pressure pumped from the pump 60 is An overflow type first pressure regulating valve 62 regulates the first line hydraulic pressure Pl ₁ . The first pressure regulating valve 62 generates a first line pressure Pl ₁ that increases in accordance with the throttle pressure output from a throttle valve opening detection valve (not shown), and outputs it via a first line oil passage 64. Second pressure regulating valve 66
Is an overflow type pressure regulating valve, and is a first pressure regulating valve 6
By adjusting the hydraulic oil flowed out from the No. 2 on the basis of the throttle pressure, the second line pressure Pl ₂ corresponding to the output torque of the engine 10 is generated. Third pressure regulating valve 6
Reference numeral 8 is a pressure reducing valve which uses the first line pressure Pl ₁ as a source pressure and generates a constant third line pressure Pl ₃ . Further, the manual valve 70 generates the R range pressure P _R when the shift operation lever 196 is in the R range. And 0
The R valve 72 selects and outputs the higher one of the pressure P _B2 for activating the brake B ₂ and the R range pressure P _R which are engaged when the gear is in the second speed or higher.

The clutch switching valve 52 is provided in the release side oil chamber 3
3, the release side port 80 communicating with 3, the engagement side port 82 communicating with the engagement side oil chamber 35, the input port 84 to which the second line pressure Pl ₂ is supplied, the engagement side oil chamber when the lockup clutch 32 is released. 35, a first discharge port 86 for discharging the hydraulic oil in 35, a second discharge port 88 for discharging the hydraulic oil in the release side oil chamber 33 when the lockup clutch 32 is engaged, a second
A supply port 90 to which a part of the hydraulic oil discharged from the pressure regulating valve 66 is supplied for cooling during the engagement period of the lockup clutch 32, a spool valve element 92 for switching the connection state of these ports, and its spool. A spring 94 for urging the valve element 92 toward the off-side position, a plunger 96 arranged so as to be capable of contacting the end of the spool valve element 92 on the spring 94 side, and end surfaces of the spool valve element 92 and the plunger 96. An oil chamber 98 provided therebetween for applying the R range pressure P _R , and an oil chamber 100 receiving the first line pressure Pl _{1 applied} to the end surface of the plunger 96.
And an oil chamber 102 that receives the switching signal pressure P _sw in order to apply the switching signal pressure P _sw from the third solenoid valve 50 to the end surface of the spool valve element 92 to generate thrust toward the ON side position. Is equipped with.

In the non-excited state (OFF state), the third solenoid valve 50 blocks the communication between the oil chamber 102 and the OR valve 72 by the spherical valve element and makes the oil chamber 102 a drain pressure, but in the excited state (ON state). (State), the oil chamber 102 and the OR valve 72 are communicated with each other, and the switching signal pressure P _sw is applied to the oil chamber 102. Therefore, when the third solenoid valve 50 is off, the oil chamber 1
No switching signal pressure P _sw from the third solenoid valve 50 is applied to 02, and the spool valve element 92 is turned off in accordance with the biasing force of the spring 94 and the first line hydraulic pressure Pl ₁ acting on the oil chamber 100. Since the input port 84 and the disengagement side port 80 are communicated with each other and the engagement side port 82 and the first discharge port 86 are communicated with each other, the oil pressure P _off in the disengagement side oil chamber 33 is equal to the engagement side oil. At the same time as the lockup clutch 32 is released by being raised above the hydraulic pressure P _on in the chamber 35, the working oil in the engagement side oil chamber 35 is transferred to the first discharge port 86, the oil cooler 104, and the check valve 106. It is discharged to the drain through.

On the contrary, when the third solenoid valve 50 is on, the switching signal pressure P _sw from the third solenoid valve 50 is set.
Is applied to the oil chamber 102 and the spool valve element 92 is positioned at the on-side position against the biasing force of the spring 94 and the first line hydraulic pressure Pl ₁ acting on the oil chamber 100. Since the engagement side port 82, the release side port 80 and the second discharge port 88, and the supply port 90 and the first discharge port 86 are made to communicate with each other, the hydraulic pressure P _on in the engagement side oil chamber 35 is the release side oil chamber. pressure P is also increased from _off the lock-up clutch 32 in 33 at the same time is engaged, the discharge hydraulic fluid in the release side oil chamber 33 into the drain through the second discharge port 88 and the slip control valve 56 To be done.

The linear solenoid valve 54 is a pressure reducing valve whose source pressure is a constant third line pressure Pl ₃ generated by the third pressure regulating valve 68. As shown in FIG. The slip control signal pressure P _lin is generated that decreases as the drive current I _sol increases, and the slip control signal pressure P _{lin is applied} to the slip control valve 56. The linear solenoid valve 54 includes a supply port 110 to which the third line pressure Pl ₃ is supplied, an output port 112 for outputting a slip control signal pressure P _lin , a spool valve 114 for opening and closing them, and a spool valve 114 thereof. 116 for urging the valve in the valve opening direction and the drive current I _sol
Slip control electromagnetic solenoid 118 for urging spool valve 114 in the valve closing direction in accordance with
An oil chamber 1 for receiving a feedback pressure (slip control signal pressure P _lin ) for generating thrust in the valve closing direction
20, the spool valve element 114 is operated so that the urging force in the valve opening direction by the spring 116 and the urging force in the valve closing direction by the slip control electromagnetic solenoid 118 and the feedback pressure are balanced.

The slip control valve 56 includes a line pressure port 130 to which the second line pressure Pl ₂ is supplied, a receiving port 132 for receiving the hydraulic oil in the release side oil chamber 33 discharged from the second discharging port, and its receiving port 132. A drain port 134 for discharging the hydraulic oil received in the receiving port 132
And the receiving port 132 and the drain port 134 are communicated with each other to discharge the hydraulic oil in the release side oil chamber 33, so that the pressure difference ΔP between the engagement side oil chamber 35 and the release side oil chamber 33.
The direction toward the first position (the lower position in FIG. 4) for increasing (= P _on −P _off ) and the receiving port 132 and the line pressure port 130 are communicated with each other, and the second is provided in the release side oil chamber 33. By supplying the line pressure Pl ₂ , the spool valve element 136 movably provided in the direction toward the second position (upper position in FIG. 4) where the ΔP is reduced and the spool valve element 136 are A plunger 138 abuttable on the spool valve element 136 to urge the spool valve element 136 toward the position, and the plunger 138 and the spool valve element 136.
A signal pressure oil chamber 140 that receives the slip control signal pressure P _lin in order to generate a thrust in a direction in which the plunger 138 and the spool valve element 136 are separated from each other by causing the slip control signal pressure P _lin to act on The plunger 138 is acted upon by the hydraulic pressure P _off in the release side oil chamber 33 to cause the plunger 138 to move the spool valve element 136 to its first position.
The hydraulic pressure P in order to generate thrust in the direction toward the position
an oil chamber 142 for receiving the _off, hydraulic pressure P _on in order to the spool 136 by the action of pressure P _on the engaging oil chamber 35 generates a thrust in a direction toward its second position to spool 136 And a spring 146 housed in the signal pressure oil chamber oil chamber 140 and biasing the spool valve element 136 toward the second position.

Here, the plunger 138 is formed with a first land 148 and a second land 150 having cross-sectional areas A ₁ and A ₂ which become smaller from the oil chamber 142 side, and a spool valve element 136. Includes a third land 152 having a cross-sectional area A ₃ from the signal pressure oil chamber 140 side and a fourth land 15 having a cross-sectional area A ₄ smaller than the cross-sectional area A _3.
Fourth and fifth lands 156 are formed. The cross-sectional areas of those lands have a relationship of A ₃ > A ₁ (= A ₄ )> A ₂ . Therefore, when the slip control signal pressure P _lin is relatively small and the relationship shown in Formula 1 is established, the plunger 138 abuts the spool valve element 136 and operates integrally with each other, and the slip control signal pressure P _lin. A pressure difference ΔP having a magnitude corresponding to is formed. At this time, the pressure difference Δ
P changes relatively gently in accordance with the slope [(A ₃ −A ₂ ) / A ₁ ] according to Expression 2 with respect to the slip control signal pressure P _lin . In Equation 2, F _s is the spring 1
46 is a biasing force.

[0021]

[Equation 1]

[0022]

[Equation 2]

However, when the slip control signal pressure P _lin becomes larger than the predetermined value P _A , the relationship shown in the equation 3 is established. This predetermined value P _A is a value that is predetermined so as to obtain a change range ΔP _SLP of the pressure difference ΔP that is sufficient for slip control of the lockup clutch 32, and is a slip control signal. The respective cross-sectional areas and the like are set so that the relationship shown in Formula 3 is established when the pressure P _lin reaches this value P _A. For this reason, the plunger 138 and the spool valve 136 are separated from each other, and the spool valve 136 is operated so that the equation 4 is established. However, in the state where the spool valve element 136 is operated so as to satisfy the equation 4, the slip control valve 56
Is set so that the receiving port 132 and the drain port 134 are communicated with each other, the hydraulic pressure P _off in the release side oil chamber 33 further decreases to atmospheric pressure, and therefore ΔP = P _on , The pressure difference is sufficient to allow full engagement.

[0024]

[Equation 3]

[0025]

[Equation 4]

The solid line in FIG. 6 indicates the pressure difference ΔP obtained by the operation of the slip control valve 56 constructed as described above.
The change characteristic of the slip control signal pressure P _lin is shown. The broken line in FIG. 6 shows the change characteristic of the pressure difference ΔP in the conventional direct coupling clutch control valve with respect to the slip control signal pressure P _lin , and the slope is steeper than that of the solid line.

Returning to FIG. 2, the electronic shift control device 42 is shown.
Is a so-called microcomputer including a CPU 182, a ROM 184, a RAM 186, an interface (not shown), and the like, and includes a throttle sensor 188 for detecting an opening of a throttle valve provided in an intake pipe of the engine 10 and a rotation speed of the engine 10. Engine speed sensor 190 for detecting the speed, the input shaft 2 of the automatic transmission 14
The input shaft rotation sensor 192 that detects the rotation speed of 0, the counter shaft rotation sensor 194 that detects the rotation speed of the counter shaft 40 of the automatic transmission 14 to calculate the vehicle speed V, and the operation position of the shift operation lever 196, that is, L , S, D,
A signal representing the throttle valve opening θ _th from the operation position sensor 198 for detecting any one of the N, R, and P ranges,
A signal representing the engine rotation speed N _e (pump impeller rotation speed N _P , that is, the input side rotation speed of the lockup clutch 32), the input shaft rotation speed N _in (turbine impeller rotation speed N
_T , that is, a signal representing the output side rotation speed of the lockup clutch 32, the output shaft (counter shaft) rotation speed N _out
And a signal indicating the operation position P _s of the shift operation lever 196 are supplied. The CPU 182 of the electronic control unit 42 processes an input signal according to a program stored in advance in the ROM 184 while utilizing the temporary storage function of the RAM 186, and the automatic transmission 14
The first solenoid valve 46, the second solenoid valve 48, the third solenoid valve 50, and the linear solenoid valve 54 are respectively controlled to execute the shift control and the lockup clutch 32 engagement control.

On the other hand, the vehicle has a cruise control electronic control device 200 for maintaining a constant vehicle speed, a control switch device 202 including a set switch, a release switch, a return switch, a deceleration switch, and an acceleration switch, and a speed control device, for example. A vehicle speed sensor 204 for detecting the vehicle speed V in the meter and a cancel switch device 206 for stopping the constant speed control when the brake is operated, the clutch is operated, and the shift lever is operated to the N or P range are provided. .. This cruise control electronic control unit 200 is composed of a microcomputer similar to the shift electronic control unit 42, and the actual vehicle speed V is set with the set vehicle speed set by the control switch device 202 as a target value. The throttle actuator 208 is driven so as to be maintained, and the throttle valve opening θ _th, that is, the output of the engine 10 is adjusted so that the vehicle speed becomes constant regardless of the change in the running resistance. In addition, the cruise control electronic control unit 2
00 supplies a signal SCC indicating execution of the constant speed control to the electronic shift control device 42 during a constant speed control period during which the engine output is controlled so that the set vehicle speed V is maintained.

In the shift control of the shift electronic control unit 42,
A shift diagram corresponding to an actual shift gear is selected from a plurality of shift diagrams stored in advance in the ROM 184, and the running state of the vehicle, such as the throttle valve opening θ _th and the output shaft rotation speed, is selected from the shift diagram. The shift gear is determined based on the vehicle speed calculated from N _out, and the first solenoid valve 46 and the second solenoid valve 48 are driven so as to obtain the shift gear, whereby the automatic transmission 14 operates. Clutches C ₀ , C ₁ ,
The operations of C ₂ and the brakes B ₀ , B ₁ , B ₂ , B ₃ are controlled to establish any one of the four forward gear stages. It should be noted that FIG. 3 shows a shift speed in each shift range of the shift operation lever 196 and operating states of the solenoid, the clutch, the brake, and the one-way clutch when the shift speed is established. The “○” and “×” marks represent the excited state and the non-excited state, respectively. In the columns of clutch and brake, the mark "○" represents the engaged state, and the mark "no" represents the disengaged state. In addition, "○" in the one-way clutch column
The mark indicates that the engagement state is obtained at the time of normal driving, and the non-mark indicates the non-engagement state.

In the engagement control of the lock-up clutch 32, from the relationship shown in FIG. 7 stored in advance in the ROM 184, the traveling state of the vehicle, for example, the output shaft rotation speed (vehicle speed).
Based on N _out and the throttle valve opening θ _th , it is determined whether the lock-up clutch 32 is in the disengagement region, the slip control region, or the engagement region. This relationship is selected from a plurality of relationships stored in advance according to the actual gear stage. In FIG. 7, on the release region side of the boundary line between the engagement region and the release region and on the low throttle valve opening side, the coupling effect is maintained to improve fuel efficiency as much as possible without impairing drivability. A slip control region that absorbs torque fluctuations of the engine 10 is provided.

When it is determined that the running state of the vehicle is within the engagement region shown in FIG. 7, the third solenoid valve 50 is excited and the clutch switching valve 52 is turned on, and at the same time, the linear solenoid valve 54 is turned on. The drive current I _sol for the lockup clutch 3 is set to the minimum drive current (rated value).
2 are engaged. Further, when it is determined that the traveling state of the vehicle is within the release region shown in FIG. 7, the third solenoid valve 50 is de-energized and the clutch switching valve 52 is turned off. Drive current I
_{Since sol} is set to the maximum drive current value, the lockup clutch 32 is released. When it is determined that the traveling state of the vehicle is within the slip control area shown in FIG. 7,
The slip control is started, the third solenoid valve 50 is excited, the clutch switching valve 52 is turned on, and at the same time, the drive current I _sol for the linear solenoid valve 54 is adjusted according to, for example, Equation 5. That is, for example, the target slip rotation speed N _slip ^T in the steady state and the actual slip rotation speed N _slip (= N _e −) determined from the relationship shown in FIG.
As N _T) deviation between ^{_{ΔN (= N slip -N slip T}} ) is eliminated, the drive current I to the linear solenoid valve 54
_sol is calculated and its drive current I _sol is output.
This causes the slip control valve 56 to drive its drive current I _sol.
Since the pressure difference ΔP between the engagement-side oil chamber 35 and the disengagement-side oil chamber 33 is adjusted so that the slip rotation speed N _slip corresponds to the slip rotation speed N _slip , the actual slip rotation speed N during the slip control period.
_{The slip} is made to follow the target slip rotation speed N _slip ^T.

[0032]

[Equation 5]

FIG. 9 shows a sudden increase in the engine speed N _e that occurs when the vehicle state deviates from the slip region to the release region in association with the increase in running resistance of the vehicle during slip control of the lockup clutch 32. 10 shows a routine showing an operation for changing the target slip rotation speed N _slip in order to prevent any _excessive increase. Step 1 of FIG.
00, it is determined whether or not the cruise control is performed, in other words, whether or not the cruise control electronic control unit 200 is performing constant speed control, based on the signal SCC from the cruise control electronic control unit 200. To be done. If the determination in step 100 is negative, in step 105, the target slip rotation speed is determined based on the actual input shaft rotation speed N _in and the throttle valve opening θ _th from the prestored relationship shown in FIG. 8, for example. After N _slip ^T is determined, this routine is ended.

However, if the determination in step S100 is affirmative, in step 101 the actual vehicle speed V _i (value at time i) is read based on the signal from the vehicle speed sensor 204, and in step 102, for example, The reference throttle valve opening degree θ _a is determined from the pre-stored road road map shown in FIG.
This road road map shows the relationship between the vehicle speed V and the corresponding resistance R, which is the sum of the rolling resistance including the loss of the drive system of the vehicle and the air resistance of the vehicle, with the road surface gradient (%) corresponding to the gradient resistance as a parameter. The reference throttle valve opening degree θ _a is a value for generating an engine output commensurate with the running resistance at that time in order to maintain the vehicle speed V at that time when traveling on a flat road.

In the following step 103, the actual throttle valve opening θ _i (value at time i) is read based on the signal from the throttle sensor 188, and in step 104, the actual throttle valve opening θ _i read by equation 103 from step 6 is read. Throttle valve opening θ _i and step 10
The target slip rotation speed N _slip ^T is calculated based on the reference throttle valve opening θ _a determined by 2. That is, the target slip rotation speed N _slip ^T is changed so as to increase according to the opening difference (θ _i −θ _a ) between the actual throttle valve opening θ _i and the reference throttle valve opening θ _a . is there. Note that in Equation 6, N _O is a basic target slip rotational speed in a state in which the constant speed control is not being executed, is determined for example as in step 105. Further, k is a constant for giving a target slip rotation speed increase proportional to the throttle valve opening difference (θ _i −θ _a ).

[0036]

[Equation 6]

In the slip control of the electronic shift control device 42, the linear solenoid is arranged so that the target slip rotation speed N _slip ^T determined by the routine shown in FIG. 9 and the actual slip rotation speed N _slip ^T coincide with each other. Valve 54
Is driven. Here, in a predetermined traveling state of the vehicle, as shown in FIG. 11, the throttle valve opening θ _th is increased to 25% or more in association with the increase in traveling resistance, as shown in FIG. Consider the process in which the point indicating the point deviates from the slip region to the release region. In the conventional case, as shown by the broken line in FIG. 12, the slip rotation speed (the rotation speed difference of the lockup clutch 32) N is released after the lockup clutch 32 is released from the point A to the point B.
_{Although the slip} rapidly increases and reaches the point C, in the present embodiment, the slip rotation speed (the rotation speed difference of the lockup clutch 32) N _slip is linear from the point A as shown by the solid line in FIG. Increase to reach point C. That is, to explain with reference to the output torque map of the engine 10 of FIG. 13, conventionally, from the point A to the point B with the increase of the throttle valve opening θ _th.
In the process of reaching the point, the output torque T _e increases with the engine rotation speed N _e hardly increasing, and the lockup clutch 32 is released thereafter to move from the point B to the point C along the equal torque line. Although the speed N _e rapidly increases, in the present embodiment, the engine speed N _e and the output torque T _e continuously increase because they change linearly from the point A to the point C.

As described above, according to this embodiment, the actual throttle valve opening θ _i detected in step 103 is
And step 1 corresponding to the reference throttle valve opening determination means
In accordance with the opening difference (θ _i −θ _a ) from the reference throttle valve opening θ _a determined by 02, the target slip rotation speed N _slip ^T is increased in step 104 corresponding to the target slip rotation speed changing means. Be done. Therefore, when the traveling resistance increases due to the vehicle traveling at a constant speed traveling on an uphill road or the like, the throttle valve opening θ _th is _adjusted by the cruise control electronic control unit 200 in order to avoid a decrease in the vehicle speed. Although is increased, at the same time, in accordance with the opening degree difference between the flat actual throttle valve opening theta _i which is the increased and reference throttle valve opening angle theta _a to maintain the vehicle speed at that time in the running road surface Since the target slip rotation speed N _slip ^T is increased, the slip amount of the lockup clutch 32 is increased from the time when the throttle valve opening θ _th is increased, so that the engine rotation speed N _e is continuously increased. At the same time, the output torque T _e is increased and the vehicle speed V is increased. Therefore, even if the vehicle state deviates from the slip region of the lockup clutch to the release region, there is no sudden increase in engine speed,
No discomfort occurs.

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

For example, in the above-mentioned embodiments, the vehicle provided with the torque converter 12 with the lockup clutch has been described, but a vehicle provided with the fluid coupling with the lockup clutch is also acceptable.

Further, in step 104 of the above-described embodiment, the target slip rotation speed N _slip ^{T is} successively _calculated according to the equation (6).
Was linearly increased, but may be increased non-linearly according to a temporary delay function or the like.

In the above-described embodiment, the cruise control electronic control unit 20 for driving the vehicle at a constant speed is used.
Although the vehicle having 0 is described, when the driver is traveling at a relatively constant speed, when the vehicle enters an uphill road, the throttle valve opening θ _th is increased to maintain the constant speed traveling. Since the lockup clutch 12 is switched from the slip control to the disengaged state when the lockup clutch 12 is engaged, the present invention can be applied to such a case. In this case, it is judged that the amount of change in the running resistance R of the vehicle, which is grasped from the throttle valve opening θ _th and the vehicle speed V, exceeds a predetermined value, and the steps from step 101 onward are executed, or the running resistance R The step of determining that the lockup clutch 12 is switched from the slip control to the disengaged state and executing step 101 and subsequent steps can be used instead of step 100 of FIG.

Further, in the above-mentioned embodiment, the stepped planetary gear type automatic transmission 14 is provided at the rear stage of the torque converter 12, but it may be a continuously variable transmission.

The above is merely an embodiment of the present invention, and the present invention can be modified in various ways without departing from the spirit of the invention.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the gist of the present invention.

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

3 is a chart for explaining the relationship between the combination of the operation of the first solenoid valve and the second solenoid valve and the shift speed obtained thereby in the automatic transmission provided in the fluid transmission of FIG.

FIG. 4 is a diagram illustrating a configuration of a main part of the hydraulic control circuit of FIG.

5 is a diagram showing output characteristics of the linear solenoid valve of FIG.

6 is a characteristic of a slip control valve provided in the hydraulic control circuit of FIG. 4, illustrating a relationship between a pressure difference ΔP between an engagement oil chamber and a release oil chamber and a slip control signal pressure P _lin. FIG.

FIG. 7 is a diagram showing a relationship between a running state of a vehicle and an engaged state of a lockup clutch, which is stored in the electronic control unit of FIG.

8 is stored in the electronic shift control device of FIG. 2;
It is a figure which shows the relationship for determining the target slip rotation speed at regular time.

9 is a flowchart illustrating an essential part of the operation of the electronic shift control device of FIG. 2, which is an operation of changing a target slip rotation speed in slip control.

FIG. 10 is a diagram showing a relationship used in step 102 of FIG.

FIG. 11 is a diagram corresponding to FIG. 7 for explaining the action obtained as a result of the operation shown in FIG. 9.

FIG. 12 is a diagram for explaining changes in the slip rotation speed of the lockup clutch obtained as a result of the operation shown in FIG.

FIG. 13 is a diagram for explaining the operation shown in FIG. 12 on an output torque map of the engine.

[Explanation of symbols]

12: Torque converter (fluid type transmission device) 32: Lock-up clutch 33: Disengagement side oil chamber 35: Engagement side oil chamber 188: Throttle sensor (throttle valve opening detection means) 194: Counter shaft rotation sensor (vehicle speed detection means) ) Step 102: Reference throttle valve opening degree determining means Step 104: Target slip rotation speed changing means

Claims (1)

[Claims] 1. A fluid transmission with a lock-up clutch for a vehicle, wherein a lock-up clutch is operated according to a pressure difference between an engagement-side oil chamber and a release-side oil chamber, the lock being controlled by controlling the pressure difference. A slip control device for adjusting a slip amount of an up clutch to a target slip rotation speed, the vehicle speed detecting means for detecting a vehicle speed, a throttle valve opening detecting means for detecting a throttle valve opening, Reference throttle valve opening degree determining means for determining a reference throttle valve opening degree for maintaining the vehicle speed on a flat road surface based on the vehicle speed detected by the vehicle speed detecting means from the stored road load diagram The actual throttle valve opening detected by the throttle valve opening detection means and the reference throttle valve opening determination means. Has been in accordance with the opening degree difference between the reference throttle valve opening, the slip lockup clutch control apparatus for a vehicle, which comprises a target slip rotational speed changing means for increasing the target slip rotational speed, a.