JPH0942440A - Degradation detection device for friction engagement device - Google Patents

Abstract

(57) A friction engagement device such as a lock-up clutch that can be slip-engaged can detect deterioration of a friction material or oil that affects stick-slip with high accuracy. A clutch pressure Pcl is changed to change an engine rotation speed Ne and an input shaft rotation speed (turbine rotation speed) Ni.
Continuously changing the slip amount v, which is the difference in rotation speed between
Deterioration of the friction material and oil is judged based on the changing speed (dNe / dt) of the engine rotation speed Ne. Rate of change (d
The solid line in (Ne / dt) is a normal graph, and the alternate long and short dash line and the broken line are graphs when deterioration occurs. Deterioration is judged based on the difference in characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deterioration detecting device for a friction engagement device, and more particularly to a device for detecting deterioration of a friction engagement device which may be slip-engaged with high accuracy.

[0002]

2. Description of the Related Art A lock-up clutch is engaged (completely engaged) by frictional force in order to eliminate a rotational loss of a torque converter or a fluid coupling, and also to improve fuel economy, for example. When the vehicle travels within the slip control range provided in the engagement diagram for the lock-up clutch, or when the engine speed is maintained above the fuel cut speed during deceleration, a predetermined friction force is applied. The friction material may be in a slip engagement state in which the friction material is in sliding contact with each other and relatively rotates. In this slip engagement, predetermined torque transmission is performed and transmission of torque fluctuations and the like is prevented, but so-called shudder may occur due to torque fluctuations caused by stick-slip of the lockup clutch. Stick-slip is likely to occur due to changes in the friction coefficient due to deterioration of the friction material of the lock-up clutch and oil, so it is necessary to detect the friction coefficient during slip engagement and check whether the friction coefficient falls within a predetermined range. It has been proposed, for example, in Japanese Patent Laid-Open No. 5-180330 to determine whether the lockup clutch is deteriorated based on whether or not the clutch is deteriorated, and inhibit the slip control when the clutch is deteriorated to prevent the occurrence of shudder.

[0003]

By the way, the friction coefficient of the lock-up clutch varies depending on the engaging pressure and temperature of the clutch, the slip amount (relative rotation speed), and so on. Therefore, the absolute value of the friction coefficient is not always necessary. The deterioration could not be determined with high accuracy. Also, if there is no change in the change characteristic of the friction coefficient with respect to the slip amount, and only if it fluctuates up and down as a whole, the amount of change in the friction coefficient is controlled by feedback control of the engagement pressure so that the predetermined slip amount is obtained. Since it is absorbed by the engagement pressure, it has almost no effect on the slip engagement, but the slip control is prohibited more than necessary. That is, when the change characteristic of the friction coefficient with respect to the slip amount, for example, the change rate changes, even if the engagement pressure is feedback-controlled so that the predetermined slip amount is obtained, the change characteristic of the friction coefficient due to a slight change in the slip amount is However, the stick control may be more likely to occur, but conventionally, the slip control was prohibited more than necessary only by changing the absolute value of the friction coefficient, and the effect of the slip control was not sufficiently obtained.

The present invention has been made in view of the above circumstances, and it is an object of the present invention that in a friction engagement device such as the lock-up clutch, deterioration of a friction material or oil that affects stick-slip is high. It is to be able to detect with accuracy.

[0005]

In order to achieve the above object, the deterioration determination is performed based on the change characteristic of the friction coefficient with respect to the change of the slip amount which is not affected by the engagement pressure and the temperature, for example, the change rate. The present invention relates to a device for detecting deterioration of a friction engagement device which may be slip-engaged, comprising: (a) changing the slip amount of the friction engagement device, Change characteristic detecting means for detecting a change characteristic of the friction coefficient with respect to change or a predetermined physical quantity changing in association with the change of the change characteristic; and (b) change characteristic of the friction coefficient detected by the change characteristic detecting means, or And a deterioration determining unit that determines deterioration based on a predetermined physical quantity that changes in association with the change in the change characteristic.

[0006]

That is, unlike the absolute value of the friction coefficient, the change characteristic of the friction coefficient with respect to the change in the slip amount, for example, the change rate, is not significantly affected by the change in the engaging pressure and temperature of the clutch, and the friction material and If it changes due to deterioration of the oil, the change characteristic of the friction coefficient due to a slight change in the slip amount during slip control may change, and stick slip may easily occur. The deterioration is determined based on the predetermined physical quantity that changes in association with the change in the change characteristic. As a result, the accuracy of determining deterioration of friction materials and oil that affects stick-slip and shudder is greatly improved.
High reliability can be obtained, and slip control will not be unnecessarily prohibited compared to the conventional device that prohibits slip control even if the absolute value of the friction coefficient changes overall. Therefore, it becomes possible to fully enjoy the benefits of fuel efficiency improvement and the like due to the slip control.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Here, the present invention is suitable for determining the deterioration of a lockup clutch which is arranged in parallel with a fluid transmission such as a torque converter and which directly connects a drive source such as an engine and an automatic transmission. Of course, it can be used as a friction clutch or friction brake that can be positively slip-engaged during use when engaging and disengaging a plurality of clutches and brakes during a gear shift in an automatic transmission for a vehicle. Can be similarly applied to the friction engagement device. The slip control may be a feedback control or the like in which the slip amount is controlled to be a predetermined slip amount for a relatively long time, or the slip amount may be changed in a predetermined slip pattern at the time of engagement and release. The control itself at the time of slip engagement is not particularly limited.

Further, the change characteristic of the friction coefficient with respect to the change of the slip amount is a change rate, a differential value of the change rate, a change pattern such as an increase or decrease, and the like, and a predetermined change that is associated with the change of the change characteristic. In the case of a lockup clutch, the physical quantity is, for example, the changing speed of the engine rotation speed that changes in association with the change in the changing rate of the friction coefficient.
The change characteristic of the friction coefficient with respect to the change of the slip amount differs depending on the type of the friction material or the oil. Therefore, the change characteristic detected by the change characteristic detecting unit or the predetermined physical quantity is the change characteristic of the friction coefficient of each friction engagement device. Accordingly, it is necessary to set a value that changes due to deterioration of the friction material and oil and causes the change to cause stick-slip. Since the stick slip is more likely to occur as the slip amount is smaller, it is desirable to make the deterioration determination based on the change characteristic of the friction coefficient particularly in a low slip region, for example, when the slip amount is about several tens to hundred rpm.

Further, (c) the change characteristic of the friction coefficient or its change so that the magnitude (absolute value) of the change rate of the friction coefficient with respect to the change of the slip amount is substantially equal to or less than a predetermined value. If a slip amount changing means for changing the slip amount at the time of slip control based on a predetermined physical amount that changes in relation to the characteristics is provided, the friction coefficient of a slight variation in the slip amount at the time of slip control by feedback control etc. The slip amount during the slip control is set so that the change is equal to or less than the predetermined amount. This makes it possible to perform slip control while suppressing the occurrence of stick slip and even shudder, regardless of individual differences and deterioration of friction materials and oil, and to reduce the initial set value or range of slip amount during slip control to a low slip amount. Since it can be expanded to the side, heat generation is reduced and the durability of the friction engagement device is improved.

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a vehicle power transmission device to which an embodiment of the present invention is applied. In the figure, the output of the engine 10, which is a power source, is transmitted from a torque converter 12 and an automatic transmission 14 which are fluid type transmission devices to a drive wheel through a differential gear device (not shown) and the like. The torque converter 12 is the engine 1
Pump wheel 18 connected to crankshaft 16
And a turbine wheel 22 fixed to the input shaft 20 of the automatic transmission 14 and rotated by receiving oil from the pump wheel 18, and fixed to 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. The lockup clutch 32 becomes a disengaged state (released state) 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, and the input / output rotational speed ratio of the torque converter 12 is reached. While the torque is transmitted at an amplification factor corresponding to the lockup clutch 32, the lockup clutch 32 is engaged when the hydraulic pressure in the engagement side oil chamber 35 is higher than that in the release side oil chamber 33.
The engine output is transmitted from the crankshaft 16 to the input shaft 20 via. The lockup clutch 32 has a clutch pressure Pcl (= Pon-P) which is a differential pressure between an engagement hydraulic pressure Pon in the engagement side oil chamber 35 and a release hydraulic pressure Poff in the release side oil chamber 33.
OFF) corresponds to a wet type friction engagement device in which a friction material is pressed and engaged with an engagement pressure corresponding to the friction pressure.

The automatic transmission 14 is provided with a plurality of sets of planetary gear devices and a friction engagement device such as a friction clutch or a friction brake that selectively engages the elements thereof, and has a stepped ratio that changes the gear ratio stepwise. In the transmission, the shift stage is switched according to the shift command signal from the electronic control unit 42, and the input shaft 2
The rotation of 0 is shifted at a predetermined gear ratio and output from the output shaft 34. However, it is also possible to employ a continuously variable transmission that continuously changes the gear ratio. Further, in the vehicle of this embodiment, a shift hydraulic control circuit 44 for controlling the gear ratio of the automatic transmission 14 and a lockup hydraulic control circuit 46 for controlling the engagement of the lockup clutch 32 are provided. The shift hydraulic control circuit 44 switches the forward four shift speeds by a combination of the operating states of the pair of solenoid valves 48 and 50, and switches a manual shift valve (not shown) by operating the shift lever 96. As a result, the reverse gear, parking, and neutral are established.

The lockup hydraulic control circuit 46 is switched between a linear solenoid valve 52 and a disengagement side position where the lockup clutch 32 is disengaged and an engagement side position where the lockup clutch 32 is engaged. Valve 5
4 and a slip control valve 5 whose source pressure is a regulator pressure Pr generated according to a throttle valve opening θ by a clutch pressure regulating valve (not shown) in a shift hydraulic control circuit 44.
6 is provided. The linear solenoid valve 52 uses a constant modulator pressure Pmodu generated in the speed change hydraulic control circuit 44 as a source pressure, and the electronic control unit 4
The output pressure Plin is continuously changed according to the duty ratio of the drive current Isol which is duty-controlled by 2, and the output pressure Plin 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 (not shown) toward a release side position,
The first port 60 to which the regulator pressure Pr is supplied
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 Plin of the linear solenoid valve 52 supplied to the switching valve 54 falls below a predetermined constant value, the spool valve element is in the OFF state in which it is located at the release side position according to the urging force of the spring 58. The second port 6
2 is blocked and the first port 60 and the third port 6
4, and communication is established between the fourth port 66 and the fifth port 68. Therefore, the release hydraulic pressure Poff in the release side oil chamber 33 is set to the regulator pressure Pr, and at the same time, the engagement hydraulic pressure Pon in the engagement side oil chamber 35 is set to the atmospheric pressure, and the lockup clutch 32 is released. However, when the output pressure Plin 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. It is switched to the ON state which is located at the engagement side position, and the fifth
While blocking the port 68, the first port 60 and the fourth port 66, and the second port 62 and the third port 64
To communicate with each other. Therefore, the engagement-side oil chamber 35
At the same time as the engagement hydraulic pressure Pon in the release side hydraulic chamber 33 becomes the regulator pressure Pr, the release hydraulic pressure Poff in the disengagement side oil chamber 33 is pressure controlled by the slip control valve 56, and the lockup clutch 3
The two are slip-engaged or released.

The slip control valve 56 includes a spring 70 for urging a spool valve (not shown) to increase the output pressure. The engagement hydraulic pressure Pon 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 is released to generate a thrust force toward the output pressure decreasing side. The release hydraulic pressure Poff in the side oil chamber 33 and the output pressure P of the linear solenoid valve 52
lin are actuated, and the release hydraulic pressure Poff is regulated so that the clutch pressure Pcl (= Pon-Poff) becomes a value corresponding to the output pressure Plin of the linear solenoid valve 52. That is, the engagement hydraulic pressure Pon and the release hydraulic pressure Poff are changed according to the output pressure Plin (driving current Isol) of the linear solenoid valve 52 as shown in FIG. 2, and the engagement hydraulic pressure Pon is changed by switching the switching valve 54.
Is set as the regulator pressure Pr, and then the release hydraulic pressure Poff is gradually decreased as the output pressure Plin rises, and the lockup is performed by the slip amount (relative rotation speed) v corresponding to the clutch pressure Pcl which is the differential pressure between them. The clutch 32 is slip-engaged, and when the release hydraulic pressure Poff drops below a predetermined value, the lock-up clutch 32 is completely engaged.

The electronic control unit 42 includes a CPU 82, R
A so-called microcomputer including an OM 84, a RAM 86, an interface (not shown), etc., in which a throttle sensor 88 for detecting an opening θ of a throttle valve provided in an intake pipe 80 of the engine 10 and a rotation speed of the engine 10 (pump Rotational speed of impeller 18) Engine speed sensor 90 for detecting Ne, automatic transmission 14
Input shaft rotational speed sensor 92 for detecting the rotational speed of the input shaft 20 (rotational speed of the turbine impeller 22) Ni, an output shaft rotational speed sensor 94 for detecting the rotational speed No of the output shaft 34 of the automatic transmission 14, and an automatic An oil temperature sensor 95 for detecting the A / T oil temperature Toil, which is the temperature of the oil of the transmission 14 and the lockup clutch 32, the operating position of the shift lever 96,
That is, from the operation position sensor 98 for detecting any one of the L, S, D, N, R, and P ranges, a signal indicating the throttle valve opening θ, a signal indicating the engine rotation speed Ne, and an input shaft rotation speed Ni. A signal indicating the output shaft rotation speed No, a signal indicating the A / T oil temperature Toil, and a signal indicating the operation position of the shift operation lever 96 are supplied.

The CPU 82 of the electronic control unit 42 is a RAM
The signal processing is performed according to the program stored in advance in the ROM 84 while using the temporary storage function of 86.
Each function shown in is executed. The gear shift control device 100 of FIG. 3 switches the gear position of the automatic transmission 14 according to a gear shift diagram that is predetermined using, for example, the throttle valve opening θ and the vehicle speed (output shaft rotation speed No) as a parameter. The operation of the solenoid valves 48 and 50 is controlled so that the stages are established. The lock-up control device 102 controls engagement and disengagement of the lock-up clutch 32 according to the flowchart shown in FIG. 4, and includes a slip control means 104 that performs feedback control so that slip engagement is performed at a predetermined target slip amount v ^*. ing.

In step Q1 of FIG. 4, it is determined whether or not the operating condition of the vehicle is the completely engageable state. If it is not the completely engageable state, it is determined in step Q2 whether the slip control is possible. Whether these complete engagement possible states and slip control possible states are basically in the complete engagement regions defined by the throttle valve opening θ and the output shaft rotation speed No as parameters as shown in FIG. Although it is determined whether or not it is in the slip control region, other conditions such as engine rotation speed Ne and A / T oil temperature Toil are set. If the determination in step Q1 is YES, that is, if the engagement is completely possible, step Q6 is executed to set the duty ratio of the drive current Isol to 1
The lockup clutch 32 is completely engaged by setting the output pressure Plin of the linear solenoid valve 52 to a high pressure. When the determinations at steps Q1 and Q2 are both NO, that is, when the release region is reached, step Q7 is executed to set the duty ratio of the drive current Isol to 0%, set the output pressure Plin to a low pressure, and set the switching valve 54 to low. The lock-up clutch 32 is released by turning it off.

If the determination in step Q2 is YES,
That is, when the slip control is possible, the slip control means 104 executes the steps after step Q3. In step Q3, for example, from the data map previously stored in the RAM or the like using the throttle valve opening θ and the input shaft rotation speed (turbine rotation speed) Ni as parameters,
The feedforward value FWD of the duty ratio that becomes the target slip amount v ^* is calculated by map interpolation. The solid line in FIG. 6 is an example of the relationship between the friction coefficient μ of the lock-up clutch 32 and the slip amount v. The friction coefficient μ is substantially constant when the slip amount v is about 50 rpm or more, but is about 50 rpm or less. The μ decreases abruptly, and even a slight change in the slip amount v at the time of slip control causes the friction coefficient μ to change significantly, and stick slip easily occurs. Therefore, the target slip amount is usually set in the range of about 50 rpm or more, but in the present embodiment, the target slip amount v ^* which is smaller than the target slip amount is set in advance. In addition,
The target slip amount v ^* can be set within a predetermined slip amount range by using the throttle valve opening θ and the input shaft rotation speed Ni as parameters. The broken line and the alternate long and short dash line in FIG. 6 show typical characteristics when the friction material and oil of the lockup clutch 32 are deteriorated.

Then, in the next step Q4, based on the deviation Δv between the actual slip amount v and the target slip amount v ^* , the feedback correction value FB for reducing the deviation Δv is set to a feedback control expression such as PID operation. Calculate according to. In step Q5, the feedback correction value FB is added to the feedforward value FWD to obtain the duty ratio of the drive current Isol, and the drive current Isol is output at that duty ratio, so that the actual slip amount v is the target slip. The output pressure Plin and the clutch pressure Pcl are adjusted so that the amount becomes v ^* .

Returning to FIG. 3, the deterioration detecting device 106 and the slip properizing device 114 perform signal processing in accordance with the flowcharts of FIGS. 7 and 8.
Reference numeral 06 denotes a change characteristic detecting means 108, a deterioration determining means 110,
And a deterioration warning means 112, and the slip optimization device 114 is provided with the change characteristic detection means 10 described above.
8, a slip amount changing means 116, and a slip control area changing means 118. The change characteristic detecting means 108 changes the clutch pressure Pcl of the lockup clutch 32 to change the slip amount v, and the change rate (dμ / d) of the friction coefficient μ with respect to the change of the slip amount v.
dv) is detected, the deterioration determining unit 110 determines deterioration of the friction material or oil of the lockup clutch 32 based on the rate of change (dμ / dv), and the deterioration warning unit 112 deteriorates. When it is determined that the deterioration has occurred, the driver is informed of the deterioration by means of display means such as lighting of a lamp and a warning sound. Further, the slip amount changing means 116
Is to change the target slip amount v ^* so that the magnitude (absolute value) of the rate of change (dμ / dv) becomes equal to or less than the appropriate value α ₁ , and the slip control area changing unit 118 uses the target slip amount. When v ^* exceeds the upper limit value v ^* max, the slip controllable region, in this embodiment, the slip control region defined in FIG. 5 is narrowed so that stick-slip is less likely to occur.

In step S1 of FIG. 7, it is determined whether or not the traveling distance L from the execution of the previous step S7 and subsequent steps is a predetermined set value L ₁ or more, and if L ₁ ≤L, step S3 and subsequent steps are performed. Is executed, but if L ₁ > L, step S
Execute Step 2. In step S2, the presence / absence of a shudder is monitored by, for example, the fluctuation cycle of the engine rotation speed Ne, and if a shudder is detected, steps S3 and thereafter are executed. In step S3, it is determined whether the slip control is possible (including during slip control). If the slip control is possible, the throttle valve opening θ is within a predetermined range θ ₁ <θ in step S4. Judge whether <θ ₂ or not. This is because the relationship between the friction coefficient μ and the slip amount v changes depending on the magnitude of the engine torque, so that the conditions relating to the engine torque are made substantially the same, and θ ₁ <θ <
If θ ₂ , then in step S5 the variation Δθ of the throttle valve opening θ is within a predetermined constant range Δθ ₁ <
It is determined whether or not Δθ <Δθ ₂ , that is, whether or not the engine torque is in a substantially steady state with small fluctuations in engine torque. And Δθ ₁ <
If Δθ <Δθ ₂ , then in step S6 the automatic transmission 14
It is determined whether or not the gear shift for switching the gear is being performed, for example, based on whether or not the gear ratio (Ni / No) is substantially constant. If not, the steps S7 and thereafter are executed.

Steps S7 and S8 are executed by the change characteristic detecting means 108. First, in step S7, the duty ratio of the drive current Isol is changed continuously or stepwise within a predetermined range. As a result, the clutch pressure Pcl is changed and the slip amount v is also changed.
The change range of the drive current Isol may be 0% to 100%, but it is determined so as to include at least the target slip amount v ^* . Further, the direction of change of the drive current Isol is changed from the smaller duty ratio to the larger one, and the slip amount v is changed from the larger one to the smaller one. Alternatively, the slip amount v may be changed from a small amount to a large amount. FIG. 9 shows the drive current Iso
6 is a time chart showing an example of changes in engine rotation speed Ne, input shaft rotation speed Ni, clutch pressure Pcl, drive current Isol, etc., when l is continuously changed from 0% to 100%. Then, in step S8, the engine torque Te, the engine rotation speed Ne, and the input shaft rotation speed Ni are read when the drive current Isol is changed, the friction coefficient μ is calculated according to the following equation (1), and the friction coefficient μ is calculated.
And a slip amount v, that is, a graph of change rate (dμ / dv) shown in FIG. 10 is obtained from the μ-v characteristic as shown in FIG. The engine speed N in FIG.
The solid line, the broken line, and the alternate long and short dash line in the graph of e and FIG. 10 correspond to the solid line, the dashed line, and the alternate long and short dash line in the graph of the friction coefficient μ shown in FIG. 6, respectively. In addition, the change rate (d
μ / dv) is the value when the slip amount v is changed in the decreasing direction, and the change rate (d
The sign of μ / dv) is opposite. _{μ = {Te -C 0 (Ne} -Ni) Ne} / A (kt-B) ··· (1)

Here, the engine torque Te is the sum of the transmission torque Tc of the lockup clutch 32 and the transmission torque Tp of the torque converter 12, and the transmission torques Tc and Tp are expressed by the following equations (2) and (3), respectively. Therefore, the above equation (1) is obtained by rewriting the following equation (4) in which they are added. In the equation (2), A is the pressure receiving area of the lockup clutch 32, t is the elapsed time, k, B
Is a constant. Further, C in the formula (3) is a capacity coefficient, and
In the vicinity of the speed ratio e = 1 which is / Ne, it is possible to approximate C = C ₀ (1-e) using the constant C ₀ . The engine torque Te is obtained as a function f (θ, Ne) of the throttle valve opening θ and the engine rotation speed Ne. Also,
Instead of (kt-B), the output pressure Plin or the like may be read. Tc = μ · A · Pcl = μ · A (kt-B) ··· (2) Tp = C · Ne 2 = C 0 (1-Ni / Ne) Ne 2 = C 0 (Ne -Ni) Ne · ·· (3) Te = μ · A (kt-B) + C 0 (Ne -Ni) Ne ··· (4)

The determination / optimization subroutine of the next step S9 is executed according to the flowchart of FIG. 8. First, at step R1, the absolute value | dμ / dv | of the rate of change (dμ / dv) in the target slip amount v ^* is determined. Then, it is determined whether or not it is equal to or less than a preset proper value α ₁ so that stick-slip does not occur due to a change in the friction coefficient μ due to a change in the slip amount v during the slip control. If the proper value α ₁ or less, step R5 and subsequent steps are immediately executed, but α ₁
If larger, | dμ / d in step R2
Target slip amount v ^* so that v | becomes equal to or less than the appropriate value α ₁
Is increased, and the slip control of steps Q3 to Q6 in FIG. 4 is performed according to the changed target slip amount v ^* . These steps R1 and R2 are executed by the slip amount changing means 116.

In step R3, the change in step R2 is performed.
Changed target slip amount v^*However, due to heat generation etc.
A predetermined upper limit within the range that does not significantly impair
Value v ^*It is judged whether it is more than max, and v^*≧ v^*became max
In step R4, stick-slip
The slip control area is narrowed so that
Together with the target slip amount v^*Is the upper limit value v^*fixed at max
I do. To reduce the slip control area, dTe / d
In order for θ and dTe / dNe to be below a predetermined value, for example,
Output shaft rotation speed No of FIG.₁To shift the high rotation side
Of the slip control that is the other execution condition of slip control.
You can increase the lower limit of the throttle valve opening θ.
Yes. If dTe / dθ and dTe / dNe become smaller, the
Fluctuations in engine torque Te during lip control become small
Therefore, stick-slip is less likely to occur. These
Steps R3 and R4 are the slip control area changing hands.
Performed by stage 118.

Step R5 is executed by the deterioration determining means 110.
Therefore, the target slip amount v ^*Change regardless of
The lockup clutch 32 based on the rate (dμ / dv)
Determine the deterioration of the friction material and oil. Specifically, FIG.
Of the normal change rate (dμ / dv) shown by the solid line at 0
Characteristic and rate of change at the time of deterioration (dμ
/ Dv) characteristics can be distinguished, for example, change rate
The maximum value of (dμ / dv) (dμ / dv) max is the deterioration judgment
If it is larger than the value β, it is determined that there is deterioration.
good. If it is determined that there is deterioration,
In step R6 executed by the warning unit 112
Driving by displaying means such as lighting of lamps and warning sounds.
Notify people of deterioration.

Here, the rate of change (dμ / dv) is less affected by the magnitude of the clutch pressure Pcl, the A / T oil temperature Toil, and the like as compared with the friction coefficient μ itself, and also causes deterioration of the friction material and oil. If it changes due to this, the change characteristic of the friction coefficient μ due to a slight change in the slip amount v at the time of slip control changes, so that stick slip may easily occur. In this embodiment, since the deterioration of the friction material or oil is determined based on such a change rate (dμ / dv) of the friction coefficient μ, the friction material or oil that affects stick-slip or shudder can be detected. The accuracy of deterioration judgment is greatly improved, and high reliability is obtained.
Compared to the conventional device in which the slip control is prohibited even if the absolute value of the friction coefficient μ is changed overall, the slip control is not prohibited more than necessary, and the benefits such as fuel consumption improvement due to the slip control are provided. You can fully enjoy it.

On the other hand, in this embodiment, the target slip amount v^*
Absolute value of change rate (dμ / dv) at | dμ / dv |
Is the friction coefficient associated with the variation of the slip amount v during slip control.
To prevent stick-slip from occurring with a change of several μ,
Set appropriate value α₁If larger, | dμ / d
v | is an appropriate value α₁Target slip amount v so that ^*
Of friction material and oil
Despite individual differences and deterioration, stick-slip and shatter
That slip control can be executed while suppressing the occurrence of
The target slip amount v^*Initial setting value of low slip amount
Since it can be expanded to the side, heat generation etc. is reduced and it locks up
The durability of the clutch 32 is improved.

Further, the target slip amount v ^* is an upper limit value v
^{* When the value} exceeds max, the slip control area is narrowed so that stick-slip is less likely to occur, so in this respect as well, it is possible to continue slip control while suppressing the occurrence of stick-slip and shudder, and improve fuel efficiency through slip control. You can enjoy benefits such as

Next, another embodiment of the present invention will be described. The flowcharts of FIGS. 11 and 12 are executed instead of the flowcharts of FIGS. 7 and 8, and steps SS8, RR1, RR2, and RR5 are different from those of the embodiment, and step SS8 is shown in FIG. Change speed (dNe / dt) of the engine speed Ne when the drive current Isol is linearly changed from 0% to 100% as described above.
Is detected instead of the rate of change (dμ / dv).

Here, the engine torque Te can be approximated by the following equation (5) in the process in which Ne approaches the output shaft rotation speed Ni in the slip control, and its changing speed (dTe / dt) is represented by the following equation (6). expressed. In these expressions (5) and (6), a and b are constants. Also, the lockup clutch 32
Assuming that the output shaft rotation speed Ni is substantially constant, the change speed (dTc / dt) of the transmission torque Tc of the following equation (7)
The change speed (dTp / dt) of the transmission torque Tp of the torque converter 12 is expressed by the following equation (8). Since the rate of change of them has the relationship of the following equation (9),
Substituting the expressions (6) to (8) into the expression and rewriting (10)
When the equation (1) is substituted into the friction coefficient μ of the equation (10), the equation (11) is obtained, and the change speed (dNe / dt) of the engine rotation speed Ne is the change rate of the friction coefficient μ ( d
It can be seen that it changes with a certain relation to μ / dv). That is, the changing speed (d of the engine rotation speed Ne)
Ne / dt) corresponds to a predetermined physical quantity that changes in association with the change of the change rate (dμ / dv) which is the change characteristic of the friction coefficient μ with respect to the change of the slip amount v, and step SS8 is the change characteristic detecting means. It is executed by means corresponding to 108. The graph of the change speed (dNe / dt) shown by the solid line, the one-dot chain line, and the broken line in FIG. 9 corresponds to the rotation speed of FIG. 9 and the solid line, the broken line, and the one-dot chain line of the graph of FIG. Te = a.Ne + b ... (5) dTe / dt = a (dNe / dt) ... (6) dTc / dt = A.k {(d.mu./dv). (Dv / dt) .t + .mu.} ≈A · k {(dμ / dv) · (dNe / dt) · t + μ} ... (7) dTp / dt = C ₀ (2Ne-Ni) · (dNe / dt) ... (8) dTe / dt = (dTc / dt) + (dTp / dt) ··· (9) dμ / dv = {a-C 0 (2Ne -Ni) -A · k · μ / (dNe / dt)} / A · k · t ··· (10) dμ / dv = _{[a-C 0 (2Ne -Ni)} - {k / (kt-B)} × {Te -C 0 (Ne -Ni) Ne} / (dNe / dt )] / A ・ k ・ t ・ ・ ・ (11)

At step RR1, the target slip amount v ^*
The change speed (dNe / dt) at the predetermined value α which is set in advance so that stick-slip does not occur due to the change of the friction coefficient μ accompanying the change of the slip amount v during the slip control.
₂ (See FIG. 9) Judge whether it is smaller than. And
If appropriate value alpha ₂ smaller than in step RR2 (dNe / dt) increases the target slip amount v ^* such that an appropriate value alpha ₂ or more. These steps RR1
And RR2 are executed by means corresponding to the slip amount changing means 116.

In step RR5, the deterioration of the friction material and oil of the lockup clutch 32 is determined based on the changing speed (dNe / dt) regardless of the target slip amount v ^* . Specifically, it suffices to be able to distinguish the characteristic of the change rate at normal time (dNe / dt) shown by the solid line in FIG. 9 from the characteristic of the change rate at deterioration (dNe / dt) shown by the alternate long and short dash line or broken line. Deterioration in the case of the one-dot chain line can be determined by whether or not the minimum value (dNe / dt) min of the speed (dNe / dt) is smaller than the deterioration determination value γ _{1 which is} smaller than the appropriate value α ₂ . In addition, the rate of change (dNe /
Deterioration in the case of the broken line can be determined by whether or not the maximum value (dNe / dt) max of dt) is greater than the deterioration determination value γ _{2 which is} greater than zero. This step RR5 is executed by means corresponding to the deterioration determining means 110.

In this embodiment, in addition to obtaining the same effects as in the first embodiment, the engine speed Ne
The rate of change (dNe / dt) can be detected easily and with high accuracy, so the accuracy of determination of oil deterioration and the like is improved.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the above embodiment, the rate of change (dμ / d
v) and the speed of change (dNe / dt) were used to judge the deterioration and the target slip amount v ^* was optimized, but it is also possible to use a value obtained by further differentiating such values, etc. The change characteristics of the friction coefficient μ and the predetermined physical quantity used for the above are appropriately determined.

Further, in the above embodiment, as shown by the solid line in FIG. 6, the characteristic that the friction coefficient μ decreases when the slip amount v decreases is the normal characteristic (before deterioration). The present invention can be similarly applied to the combination device. The criterion for determining whether or not it has deteriorated may be set by comparing the characteristic at the time of normality and the characteristic at the time of deterioration.

Further, as the judgment criteria for the above deterioration judgment,
For example, the rate of change in the target slip amount v ^* (dμ / d
Deterioration depends on whether or not the absolute value | dμ / dv | of v) is larger than a deterioration determination value set in advance so that stick-slip does not occur due to a change in friction coefficient μ due to a change in slip amount v during slip control. Is determined as appropriate.

In the above embodiment, the rate of change (dμ / d
target slip amount v based on v) etc. ^*To change
However, the target slip amount v^*Fixed to a fixed value
May be.

Further, although the lock-up clutch 32 has been described in the above-mentioned embodiment, a slip clutch such as a friction clutch or a friction brake may be slip-engaged when the shift stage of the automatic transmission 14 is changed. The present invention can be applied to various friction engagement devices.

Further, in the case where the target slip amount v ^* is set within a predetermined range according to the operating condition, or the friction engagement device for controlling the engagement / release by changing the slip amount v in a predetermined setting pattern is described above. When executing step R1,
For example, the rate of change (d
The maximum absolute value | dμ / dv | max of μ / dv) or the rate of change (dμ / dv) in the minimum slip amount vmin within the set range may be used. The same applies to the second embodiment.

Further, in step R6 of the above embodiment, the driver is only notified of the deterioration, but the slip control may be prohibited depending on the degree of the deterioration.

Although not illustrated one by one, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a power transmission device of a vehicle including a deterioration detection device according to an embodiment of the present invention.

FIG. 2 is an output pressure Pli of the linear solenoid valve in FIG.
It is a figure explaining the relationship between n and the engagement oil pressure Pon of a lock-up clutch, and a release oil pressure Poff.

FIG. 3 is a functional block diagram illustrating main functions of the electronic control device of FIG.

FIG. 4 is a flowchart illustrating specific details of the lockup control device in FIG.

FIG. 5 is a diagram illustrating an example of a determination criterion for determining whether the state is a completely engageable state or a slip controllable state in FIG.

6 is a diagram illustrating a relationship between a friction coefficient μ and a slip amount v in the lockup clutch of FIG.

FIG. 7 is a flowchart illustrating specific details of the deterioration detection device and the slip optimization device of FIG.

FIG. 8 is a flowchart illustrating the specific contents of the determination / adaptation subroutine of FIG.

9 is a time chart for explaining changes in engine speed, clutch pressure Pcl, etc. when changing the slip amount in step S7 of FIG. 7. FIG.

10 is a rate of change (d) calculated in step S8 of FIG.
It is a figure explaining (mu) / dv).

FIG. 11 is a diagram illustrating a main part of another embodiment of the present invention,
8 is a flowchart used instead of FIG. 7.

FIG. 12 is a flowchart illustrating the specific contents of the determination / adaptation subroutine of FIG.

[Explanation of symbols]

 32: Lockup clutch (friction engagement device) 42: Electronic control device 106: Degradation detection device 108: Change characteristic detection means 110: Degradation determination means

Claims (1)

[Claims] 1. A device for detecting deterioration of a friction engagement device that may be slip-engaged, wherein a slip amount of the friction engagement device is changed, and a change characteristic of a friction coefficient with respect to a change of the slip amount. Alternatively, a change characteristic detecting unit that detects a predetermined physical quantity that changes in association with a change in the change characteristic, and a change characteristic of the friction coefficient detected by the change characteristic detecting unit or a change in relation to the change characteristic And a deterioration determining unit that determines deterioration based on a predetermined physical quantity.