JPH0539856A - Control device for automatic transmission - Google Patents

Abstract

PURPOSE:To improve durable life by adjusting a physical parameter relating to the load of a frictional joint element in a load reducing direction when deterioration occurring with the elapse of time in the frictional joint performance of the frictional joint element is above a fixed value. CONSTITUTION:A control unit controls line pressure so as to make speed change time required for speed change in the case of 2nd-3rd speed shift coincide with established speed change time, and stores the above line pressure with its renewal. At the same time, deterioration in the joint performance of a clutch 27 for 3rd-4th speed change is detected from the fluctuation of speed change time to the line pressure. When the deterioration becomes above fixed value, 2nd-3rd upshift speed change line is moved toward the side of low speed to reduce a load borne by the clutch 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission, and more particularly to a control device capable of reliably detecting a reduction in the fastening performance of a friction fastening element and extending its durable life.

[0002]

2. Description of the Related Art An automatic transmission mounted on a vehicle switches between a torque converter normally connected to an output shaft of an engine, a speed change gear mechanism connected to an output shaft of the torque converter, and a power transmission path of the speed change gear mechanism. The automatic transmission is provided with a plurality of friction engagement elements, a plurality of hydraulic actuators for respectively engaging these friction engagement elements, and a hydraulic circuit for supplying hydraulic pressure to these hydraulic actuators. As a control device, a plurality of shift valves of the hydraulic circuit are switched on the basis of a predetermined shift map to switch the engagement states of the friction engagement elements so as to shift up and down.

In the hydraulic circuit, a hydraulic pressure supplied from a hydraulic pump is used to generate a throttle pressure by a throttle valve mechanically connected to a throttle valve mechanism of an engine, and the throttle pressure is pilot pressure in a throttle modulator valve. Is supplied to the pressure control valve, and the line pressure proportional to the throttle opening of the engine is generated by the pressure control valve. However, with a part of the above configuration changed, the hydraulic pressure supplied from the hydraulic pump is reduced by a solenoid reducing valve, and then duty-controlled by a duty solenoid valve to supply pilot pressure to the pressure control valve. In some cases, a line pressure proportional to the throttle opening of the engine is generated.

By the way, at the time of gear shifting, line pressure is supplied to the hydraulic actuator of the friction engagement element via one of the shift valves, and the friction engagement element is engaged by the line pressure. If the fastening performance deteriorates due to deterioration, the shift time required for shifting becomes longer, and if the performance of the hydraulic pressure adjustment system for generating line pressure becomes incorrect,
An error occurs in adjusting the line pressure, which causes a change in the shift time. As described above, since the line pressure greatly affects the performance of the automatic transmission, it is extremely important to properly control the line pressure. Therefore, Japanese Examined Japanese Patent Publication Sho 63-3183
In the publication, there is a change in the shift time due to the tolerance of the duty solenoid valve for adjusting the line pressure, and a change in the shift time due to a change in the performance of the transmission (such as a change in the friction coefficient of the friction material of the friction engagement element). There is described a technique for appropriately controlling the line pressure by learning control so as to eliminate the above, that is, to always achieve a predetermined shift time.

[0005]

According to the technique described in the above publication, the line pressure is controlled through learning control.
Since the line pressure can be corrected by taking into consideration changes over time such as wear and deterioration of the friction material of the frictional engagement element, it is possible to constantly maintain the shift time at a substantially predetermined value. However, according to the technique of this publication, the line pressure is increased when the performance of the frictional fastening element is deteriorated due to long-term use, so that the load is not reduced at all when the performance of the frictional fastening element is deteriorated, but rather the load is increased. Therefore, there is a problem that the durability life of the frictional fastening element is significantly reduced. An object of the present invention is to provide a control device for an automatic transmission that can reduce the load of the friction engagement element when its performance deteriorates and extend its durable life.

[0006]

According to a first aspect of the present invention, there is provided a control device for an automatic transmission, a torque converter connected to an output shaft of an engine, a speed change gear mechanism connected to an output shaft of the torque converter, and a speed change gear. In an automatic transmission including a plurality of friction engagement elements that switch power transmission paths of a mechanism, and a plurality of hydraulic actuators that engage the friction engagement elements, the friction engagement performance of the friction engagement elements is reduced over time. The performance deterioration state detecting means for detecting, and the physical parameter correlated to the load of the friction engagement element when the deterioration state detected by the performance deterioration state detecting means becomes a predetermined value or more, is adjusted in the direction of reducing the load. And a load adjusting means for adjusting the load.

A control device for an automatic transmission according to claim 2 is
A torque converter connected to the output shaft of the engine, and a speed change gear mechanism connected to the output shaft of the torque converter,
Control for an automatic transmission including a plurality of friction engagement elements that switch power transmission paths of a speed change gear mechanism, a plurality of hydraulic actuators that engage the friction engagement elements, and a hydraulic circuit that supplies hydraulic pressure to these hydraulic actuators A control device for an automatic transmission, comprising: a device for correcting the operating hydraulic pressure of a hydraulic circuit so that a physical parameter that correlates with a frictional engagement performance of a frictional engagement element at the time of gear shifting approaches a target value thereof. In the above, a shift line changing means for changing the shift line related to the shift to a low speed side based on the correction amount of the operating hydraulic pressure determined by the hydraulic pressure correcting means is provided.

A control device for an automatic transmission according to claim 3 is
3. The device according to claim 2, wherein the shift line changing means is configured to change the shift line when the rate of increase of the working oil pressure with respect to the minimum value of the working oil pressure is equal to or more than a predetermined value. It is a thing.

A control device for an automatic transmission according to claim 4 is:
The apparatus according to claim 1, wherein the reduced state detection means is configured to detect the reduced state of the friction engagement performance based on a rate of increase of the shift time with respect to a minimum value of the shift time during a shift. It is a feature.

[0010]

In the control device for the automatic transmission according to the first aspect, the performance deterioration state detecting means detects the state of deterioration of the friction engagement performance of the friction engaging element of the automatic transmission with time, and the load adjusting means comprises: When the deterioration state detected by the performance deterioration state detection means becomes equal to or more than a predetermined value, the physical parameter correlated with the load of the frictional engagement element is adjusted in the direction of reducing the load. Therefore, when the frictional fastening performance of the frictional fastening element is reduced, the load on the frictional fastening element is reduced to prolong the durable life of the frictional fastening element.

In the automatic transmission control device according to the second aspect of the present invention, the hydraulic pressure correction means causes the hydraulic pressure of the hydraulic circuit so that the physical parameter correlated to the frictional engagement performance of the frictional engagement element at the time of gear shifting approaches its target value. The shift line changing means changes the shift line related to the shift to the low speed side based on the correction amount of the operating oil pressure determined by the oil pressure correcting means. Therefore, when the friction engagement performance of the friction engagement element decreases and the correction amount of the operating oil pressure increases, the load on the friction engagement element is reduced and the durability of the friction engagement element is reduced by changing the shift line to the low speed side based on that. The life can be extended.

In the automatic transmission control device according to the third aspect of the present invention, basically the same operation as that of the second aspect can be obtained.
The shift line changing means is configured to change the shift line when the rate of increase of the working oil pressure with respect to the minimum value of the working oil pressure becomes equal to or higher than a predetermined value. Here, it should be noted that, as a general characteristic of the friction material of the friction fastening element, the friction coefficient of the friction material takes a substantially constant value from the start of use until a considerably large number of times of use, but After the friction coefficient temporarily increases and reaches the maximum value, the friction coefficient sharply decreases. Therefore, the rate of increase of the operating oil pressure with respect to the minimum value of the operating oil pressure does not change much from the start of use until a predetermined number of times have been used, but since the increase rate changes greatly after the friction coefficient reaches the maximum value, By changing the shift line to the low speed side when the rate of increase becomes equal to or higher than the predetermined value, the shift line can be changed after the friction coefficient reaches the maximum value, that is, when the performance of the friction material deteriorates.

In the control device for the automatic transmission according to the fourth aspect, basically the same operation as that of the first aspect can be obtained.
The performance deterioration state detection means detects the state of deterioration of the friction engagement performance based on the rate of increase of the shift time with respect to the minimum value of the shift time during the shift. As can be seen from the explanation of the action in the previous section,
The rate of increase does not change much from the start of use until a predetermined number of times of use, but the rate of increase begins to increase when the friction coefficient reaches the maximum value and the performance of the friction material deteriorates. Therefore, it is possible to reliably detect the state of decrease in the frictional engagement performance of the frictional engagement element based on the rate of increase in the transmission time with respect to the minimum value of the transmission time, which can surely reduce the load on the frictional engagement element.

[0014]

According to the automatic transmission control device of the first aspect of the present invention, since the performance deterioration state detection means and the load adjustment means are provided, the friction engagement performance of the friction engagement element is reduced to a predetermined value or more. When this happens, the load on the friction fastening element can be reduced and the durable life of the friction fastening element can be extended.

According to the automatic transmission control device of the second aspect, by providing the shift line changing means, when the friction engagement performance of the friction engagement element is deteriorated and the correction amount of the operating oil pressure is increased. By changing the speed change line to the low speed side based on that, the load on the friction engagement element can be reduced and the durable life of the friction engagement element can be extended.

According to the automatic transmission control device of the third aspect, basically the same effect as that of the second aspect can be obtained, but the shift line changing means is used to increase the operating hydraulic pressure with respect to the minimum operating hydraulic pressure. Is configured to change the shift line when the friction change factor is not less than a predetermined value, the normal shift characteristic is ensured without changing the shift line while the performance of the friction engagement element is not deteriorated. When the deterioration of the performance of (1) has progressed, the shift line can be changed to reduce the load on the friction engagement element and extend its durable life.

According to the automatic transmission control device of the fourth aspect, basically, the same effect as that of the first aspect can be obtained, but the performance deterioration state detecting means is used to shift the shift time to the minimum value of the shift time. Since it is configured to detect the state of deterioration of the frictional fastening performance based on the rate of increase in time, it is possible to reliably detect the state of deterioration of the frictional fastening performance of the frictional fastening element. It is possible to reduce the load.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. First, the mechanical structure of the automatic transmission will be described with reference to FIG. 1. The automatic transmission 10 mainly has a torque converter 2, a speed change gear mechanism 10 driven by the output of the torque converter 2, and the mechanism 10. A plurality of friction engagement elements 20, 21, 23 to 25, 27 such as clutches and brake names for switching the power transmission path of the vehicle, and one-way clutches 22, 26, and D, 2, 1, R as a traveling range are provided by these. 1 to 4 speeds in the D range, 1 to 4 speeds in the 2 range, 1 to 4 speeds in the 2 range, 1 to 1 speed in the 1 range
It is configured to obtain the second speed.

The torque converter 2 is a pump 3 fixed in a case 11 connected to the engine output shaft 1.
And a turbine 4 that is disposed opposite to the pump 3 and is driven by the pump 3 via hydraulic oil, and is interposed between the pump 3 and the turbine 4 and a transmission case 11 via a one-way clutch 6. It is provided between the stator 5 that is supported and performs a torque increasing action, and the case 11 and the turbine 4,
The lockup clutch 29 directly connects the engine output shaft 1 and the turbine 4 via the case 11. The rotation of the turbine 4 is output to the transmission gear mechanism 10 via the turbine shaft 13. A pump drive shaft 12 penetrating the turbine shaft 13 is connected to the engine output shaft 1, and a hydraulic pump 31 is driven by the drive shaft 12.

The speed change gear mechanism 10 is composed of a Ravigneaux type planetary gear device, and has a small diameter small sun gear 15 loosely fitted to the turbine shaft 13, and a large sun gear 15 loosely fitted to the turbine shaft 13 behind the sun gear 15. Diameter large sun gear 16 and small sun gear 1
5, a plurality of short pinion gears 18, a long pinion gear 17 having a front half portion meshed with the short pinion gear 18 and a rear half portion meshed with the large sun gear 16, and the long pinion gear 17 and the short pinion gear 18 are rotatably supported. And a ring gear 19 meshed with the front half of the long pinion gear 17.

A forward clutch 20 and a first one-way clutch 22 are provided in series between the turbine shaft 13 and the small sun gear 15, and these clutch 2
A coast clutch 21 is provided in parallel with 0 and 22, a 3-4 clutch 27 is provided between the turbine shaft 13 and the carrier 14, and a reverse clutch 24 is provided between the turbine shaft 13 and the large sun gear 16. It is installed. A 2-4 brake 23 (which includes a drum 23a and a band 23b), which is a band brake that fixes the large sun gear 16, is provided between the large sun gear 16 and the reverse clutch 24, and the carrier 14 and the transmission case are provided. A second one-way clutch 26 that receives the reaction force of the carrier 14 and a low reverse brake 25 that fixes the carrier 14 are provided in parallel between and. The ring gear 19 is connected to the output gear 28, and the rotation is transmitted from the output gear 28 to the left and right wheels via a differential device.

Next, the relationship between the operating states of the friction engagement elements 20, 21, 23 to 25, 27 such as clutches and brakes and the one-way clutches 22, 26 and the shift speed will be described. First, in the first speed, the forward clutch is used. 20
Is engaged and both one-way clutches 22 and 26 are locked. Therefore, the output rotation of the torque converter 2 is changed from the turbine shaft 13 to the forward clutch 2
0, input to the small sun gear 15 via the first one-way clutch 22. In this case, since the carrier 14 is fixed by the action of the second one-way clutch 26, the transmission gear mechanism 10 does not perform the differential operation of transmitting the rotation from the small sun gear 15 to the ring gear 19 via the short pinion gear 18 in a fixed manner. Operates as a gear train.
As a result, the first speed state with a large reduction ratio corresponding to the diameter ratio of the small sun gear 15 and the ring gear 19 is obtained.

Next, in the 2nd speed, the 2-4 brake 23 is operated in addition to the state of the 1st speed, and the large sun gear 1
6 is fixed, and the second one-way clutch 26 is idling. Therefore, the rotation transmitted from the turbine shaft 13 to the small sun gear 15 is transmitted to the long pinion gear 17 via the short pinion gear 18, and the long pinion gear 17 meshes with the large sun gear 1.
Since 6 is fixed, it revolves on the large sun gear 16, and the carrier 14 rotates accordingly. as a result,
Compared to the first speed state, the rotation of the ring gear 19 is accelerated by the rotation amount of the carrier 14a (revolution of the long pinion gear 17), and the second speed state in which the reduction ratio is smaller than that in the first speed state is obtained.

Next, in the 3rd speed, the 2-4 brake 23 is released from the state of the 2nd speed, and the 3-4 clutch 27 is released.
Is concluded. Therefore, the rotation of the turbine shaft 13 is input to the small sun gear 15 via the forward clutch 20 and the first one-way clutch 22 and simultaneously to the carrier 14 via the 3-4 clutch 27. As a result, the entire transmission gear mechanism 10 integrally rotates, and the third speed state in which the ring gear 19 rotates at the same speed as the turbine shaft 13 is obtained.

Next, in the 4th speed, the 2-4 brake 23, which was once released in the 3rd speed, is re-engaged. Therefore, the rotation of the turbine shaft 13 is limited to the 3-4 clutch 2
7 is input to the carrier 14, and the long pinion gear 1
However, since the large sun gear 16 meshed with the long pinion gear 17 is fixed by the 2-4 brake 23, the long pinion gear 17 is
It will rotate while revolving with the carrier 14.
As a result, the ring gear 19 meshing with the long pinion gear 17 rotates the carrier 14 (turbine shaft 13
Rotation), the long pinion gear 17 is rotated by being increased by the amount of rotation of the long pinion gear 17, whereby the fourth speed in the overdrive state is obtained. In this case, although the forward clutch 20 is in the engaged state, the rotation of the turbine shaft 13 is not input to the small sun gear 15 because the first one-way clutch 22 in series therewith idles.

Next, at the reverse speed, the reverse clutch 24 and the low reverse brake 25 are engaged, the rotation of the turbine shaft 13 is input to the large sun gear 16, and the carrier 14 is fixed. Therefore, the rotation is transmitted from the large sun gear 16 through the long pinion gear 17 to the ring gear 19 through a fixed gear train, and a reduction ratio corresponding to the diameter ratio of the large sun gear 16 and the ring gear 19 is obtained. In that case, the rotation direction of the ring gear 19 is opposite to the rotation direction of the turbine shaft 13 to the large sun gear 16.

Incidentally, the first one-way clutch 22 which transmits the rotation at the 1st to 3rd speeds and the second one which receives the reaction force at the 1st speeds
Since the one-way clutch 26 idles during coasting, the engine brake will not operate at these gears, but the third speed in the D range and the second and third speeds in the second range.
In the first speed and the first and second speeds of the first range, the parallel coast clutch 21 is engaged with the first one-way clutch 22, and in the first speed of the first range, the low reverse brake 25 is engaged in parallel with the second one-way clutch 22. So, 3rd speed of D range, 2nd and 3rd speed of 2nd range
Engine braking will be obtained at high speed. Table 1 summarizes the relationship between the above-described friction engagement elements and the operations of the one-way clutches 22 and 26 and the shift speeds.

[Table 1]

Next, referring to FIG. 2, a hydraulic circuit 30 for supplying / discharging hydraulic oil to / from hydraulic actuators for operating the friction engagement elements will be described. Here, the hydraulic actuator 23A of the 2-4 brake 23 is composed of a servo piston having an apply port 23c and a release port 23d, and the 2-4 brake 23 is engaged when hydraulic oil is supplied only to the apply port 23c. In addition, the 2-4 brake 23 is configured to be opened when hydraulic oil is not supplied to both ports 23c and 23d and when hydraulic oil is supplied to both ports 23c and 23d. The other actuators are composed of ordinary hydraulic cylinders, and are configured to engage the friction engagement elements when hydraulic oil is supplied.

The hydraulic circuit 30 has a hydraulic pump 31 mechanically driven by the engine via the pump drive shaft 12 of FIG. 1, and oil is discharged from the pump 31 to an oil passage 61. The hydraulic oil discharged from the pump 31 to the oil passage 61 is guided to the pressure adjusting valve 32. The pressure adjusting valve 32 adjusts the pressure (line pressure) of the hydraulic oil discharged from the pump 31, and is controlled by the duty solenoid valve 33. The hydraulic pressure reduced to a predetermined pressure by the solenoid reducing valve 34 is duty controlled by the duty solenoid valve 33 (valve 3
By adjusting the opening / closing time of No. 3, the drain amount is adjusted and the hydraulic pressure is controlled).
Is supplied as a pilot pressure, and the line pressure is adjusted according to the pilot pressure. The line pressure adjusted by the pressure adjusting valve 32 is the manual shift valve 35.
Is supplied to port g of The manual shift valve 35 is manually shifted to the P, N, D, 2, 1 range, and hydraulic oil is supplied from the port g to predetermined ports in each range. The port g is communicated with the ports a and e in the 1 range, communicated with the ports a and c in the 2 range, communicated with the ports a and c in the D range, and communicated with the port f in the R range. It

Port a of the manual shift valve 35
Is connected to the 1-2 shift valve 36 by an oil passage 62, and a pilot pressure controlled by a 1-2 solenoid valve 37 acts on the 1-2 shift valve 36. At the 1st speed, the 1-2 solenoid valve 37 is turned off, the spool of the 1-2 shift valve 36 is located on the left side in the figure, and the oil passage 63 communicating with the apply port 23c of the 2-4 brake 23 is communicated with the drain side. 1-2 solenoid valve 37 is turned on in the 2nd to 4th speeds, and 1-2
The spool of the shift valve 36 is located on the right side in the figure, and the hydraulic pressure from the port a is supplied to the apply port 23c of the 2-4 brake 23. Furthermore, 1-2 shift valve 36
Is the manual shift valve 35 for 1st speed of 1 range
The hydraulic oil supplied from the port e through the low pressure reducing valve 38 is supplied to the low reverse valve 25.

The hydraulic pressure from the port a of the manual shift valve 35 is also supplied to the 2-3 shift valve 39, and the 2-3 shift valve 39 is connected to the port c of the manual shift valve 35 by the oil passage 64. The pilot pressure of the -3 shift valve 39 is controlled by the 2-3 solenoid valve 40. And 2 for 1st and 2nd speed
The -3 solenoid valve 40 is turned on, the spool of the 2-3 shift valve 39 is located on the right side in the drawing, the oil passage 65 leading to the 3-4 clutch 27 is drained, and the 3-4 clutch 27 is opened. Also, in the 3rd and 4th speed, 2-3
The solenoid valve 40 is turned off, the spool of the 2-3 shift valve 39 is located on the left side in the figure, the hydraulic pressure from the port c is sent to the oil passage 65, and the 3-4 clutch 27 is engaged. The oil passage 65 is also connected to the 3-4 shift valve 41, and the pilot pressure controlled by the 3-4 solenoid valve 42 acts on the 3-4 shift valve 41.

At the 1st, 2nd and 4th speeds of the D range and at the 1st speed of the 2nd range, the 3-4 solenoid valve 42 is turned on.
The spool of the 3-4 shift valve 41 is located on the right side in the figure, and the release port 23d of the 2-4 brake 23 is
The oil passage 66 leading to is drained. Also, D range 3
In 2nd speed, 2nd and 3rd speed of 1st range, 3-4 solenoid valve 42 is turned off in 1st and 2nd speed of 1st range, and 2-3
The spool of the shift valve 39 is located on the left side in the drawing, the oil passage 66 and the oil passage 65 connected to the 2-3 shift valve 39 are communicated with each other, and the release port 23d is activated according to the operation of the 2-3 shift valve 39. The hydraulic pressure is supplied to and discharged from.
Further, the 3-4 shift valve 41 switches the supply and discharge of the hydraulic pressure between the oil passage 67 communicating with the port a and the oil passage 68 communicating with the coast clutch 21, and accordingly the coast clutch 21 is discharged.
Will also be opened and closed.

Thus, the solenoid valves 37, 40,
According to the operation of the shift valves 36, 39, 41 controlled by 42, the engagement and release of the friction engagement elements are performed as shown in Table 1 above. The shift valves 36, 39, 41 and 2
-4 In the hydraulic circuit between the brake 23 and the 3-4 clutch 27, a 1-2 accumulator 43, a 2-3 accumulator 44, a 2-4 timing valve 45, 3-2 timing for mitigating a shift shock, etc. A valve 46 and a bypass valve 47 are provided. In addition, the hydraulic circuit 3
0 to D, 2 and 1 range forward clutch 20
Oil passage 69 that sends the hydraulic pressure from port a so that
And the N-D accumulator 48 connected thereto, the oil passage 70 for sending the hydraulic pressure from the pump port f so as to engage the reverse clutch 24 in the R range, and the N connected to this.
A -R accumulator 49, a lockup control valve 50 that controls the lockup clutch 29, a lockup solenoid valve 51 that controls the lockup control valve 50, a converter relief valve 52, and the like are provided.

Next, the control system will be described. As shown in FIG. 3, a control unit 80 for controlling the automatic transmission is provided. The control unit 80 has at least an opening T of the throttle valve of the engine.
A throttle opening signal from a throttle opening sensor 81 for detecting VO and a vehicle speed V of a vehicle equipped with an automatic transmission.
A vehicle speed signal from a vehicle speed sensor 82 for detecting the engine speed, an engine speed signal from an engine speed sensor 83 for detecting the engine speed Ne, and a turbine speed signal from a sensor for detecting the speed Nt of the turbine shaft 13. Is being supplied. Then, from the control unit 80, the duty solenoid valve 33, the 1-2 solenoid valve 37, and the 2-3 solenoid valve 40.
Drive signals are supplied to the 3-4 solenoid valve 42 and the lock-up solenoid valve 51, respectively.

The control unit 80 comprises a waveform shaping circuit for shaping the waveform of the detection signal, an A / D converter, an input / output interface, a microcomputer, a drive circuit, etc., and at least the ROM of the microcomputer has at least the throttle of the engine. Based on a gear shift map (see FIG. 7) that uses a general line pressure control program that controls the line pressure so as to be proportional to the opening, a throttle opening TVO and a vehicle speed V (see FIG. 7). A control program for shift control for downshifting, a control program for line pressure learning control and 3-4 clutch load reduction control, which will be described later, peculiar to the present application, and the like are stored in advance.

Here, the line pressure learning control function 3 unique to the present application
-4 The outline of the clutch load reduction control will be described. At the time of 2-3 gear shift to shift up the automatic transmission from the 2nd gear to the 3rd gear, the engagement of the 2-4 brake 23 is released while the 3-4 clutch 27 is engaged. In the control, the line pressure is controlled so that the shift time Tc required for the shift during the 2-3 shift becomes a predetermined set shift time To, and the line pressure is stored while being updated. When the deterioration state of the engagement performance of No. 27 is detected, and the deterioration state becomes a predetermined value or more, the 2-3 shift-up transmission line is moved to the low speed side to reduce the load of the 3-4 clutch 27. It is a thing. Since the 3-4 clutch pressure supplied to the hydraulic cylinder of the 3-4 clutch 27 is the same as the line pressure, the 3-4 clutch pressure is controlled via the line pressure.

First, as shown in FIG. 5, the friction coefficient of the friction material of the 3-4 clutch 27 and other clutches and brakes remains substantially constant after the start of use until the number of gear shifts reaches a large predetermined number No. The value is maintained, but then reaches a maximum value at a predetermined number of times No, then the post-friction coefficient rapidly decreases due to the progress of wear and deterioration, and the durable life is reached at the number of shifts N1. Since the engagement performance of the 3-4 clutch 27 varies due to the variation of the friction coefficient and the variation of the performance of the transmission, the gear shifting time varies even if the line pressure is controlled to be constant, and the engagement performance is changed. The gear shift time increases with the decrease of. This increase in shift time is not preferable because it causes deterioration in responsiveness of shift up and shift down.
The line pressure is learned and controlled so that the line pressure corresponds to the state in which the engagement performance of the clutch 27 is lowered.
At the same time, as described with reference to FIG. 5, after the friction coefficient of the friction material reaches the maximum value, and when the state of deterioration of the engagement performance of the 3-4 clutch 27 becomes a predetermined value or more, 2-3 The shift-up transmission line is moved to the low speed side to reduce the load on the 3-4 clutch 27 and the 3-4 clutch 27.
It is designed to extend the durable life of.

Next, the flow chart of the routine for the line pressure learning control and the 3-4 clutch load reduction control will be described with reference to FIG.
The description will be made on the basis of Si (i = 1, 2, 3, ...
・ ・) Shows each step. When 2-3 shift up is started by the shift control (a 2-3 shift up shift command is output), this control is started, and the count of the soft timer is started (S
1), then the line pressure P _L stored in the RAM memory
There is read (S2), then the duty value D is line pressure P _L of the drive pulse of the duty solenoid valve 33 a duty value D for generating the line pressure P _L
And a predetermined function are calculated (S3), and then the drive pulse of the duty value D is output to the solenoid of the duty solenoid valve 33 (S4). Next, the turbine rotation speed signal is read (S5), the turbine rotation speed Nt is calculated based on the turbine rotation speed signal (S6), and then it is determined whether or not the shift is completed (S7).
Explaining this determination, since the engine speed before and after the shift is substantially the same because the shift time Tc is extremely short, the turbine speed at the start of the shift in FIG. 6 is Nt2 (when the second speed is selected). Rotational speed), Nt3 (rotational speed at the third speed) when the gear shift is completed, G2 is the gear ratio at the second speed, and G3 is the gear ratio at the third speed, and Nt2 / Nt3 = G2. Since there is a relationship of / G3,
Whether or not the shift is completed can be determined based on the turbine speed Nt.

If the result of determination in S7 is that gear shifting has not been completed, S4
Returning to step S4 to S7, the shift is completed, the process proceeds to step S8, the shift time Tc is calculated based on the count value of the timer, and the difference between the shift time Tc and the set shift time To is calculated. absolute value, and then determines whether the predetermined small value α less (S9), when the shift time Tc is determined Yes and in S9 equals substantially set shift time to, the line pressure for the next 2-3 shift P _L As the line pressure P _L of this time is set and stored in the memory (S10), S
When the result of the determination in No. 9 is No, the routine proceeds to S10, where it is judged whether or not the shift time Tc> To + α (S11), and the shift time Tc becomes longer due to the deterioration of the engagement performance of the 3-4 clutch 27, and when Tc> To + α. , S12, a value obtained by adding a predetermined increment Δ to the current line pressure P _L is set as the next line pressure P _L , and the determination result N of S11 is N.
When it is o, a value obtained by subtracting a predetermined predetermined decrement Δ from the current line pressure P _L is set as the next line pressure P _{L in} S13 (see FIG. 6). In this way, since the shift time Tc for 2-3 shifts is obtained and the line pressure P _L is learned and controlled so that it becomes the set shift time To, the shift time T
It is possible to prevent the fluctuation of c and prevent the deterioration of the response of the shift.

Next, from S10, S12 or S13 to S1
4, the 3-4 clutch load reduction control is executed in S14 to S17. That is, in S14, it is determined whether or not the current line pressure P _L is smaller than the line pressure minimum value Pmin stored in the memory while being updated.
When s, the minimum line pressure value Pmin is replaced with the current line pressure P _L and stored in the memory (S15), and N
When O, P _L / Pmin ≧ K (where K is 1.10)
˜1.30) or not (S1)
6). The minimum line pressure value Pmin is the line pressure P _L corresponding to the number of gear shifts No. in FIG. 5, and in view of the fact that the fastening performance sharply decreases when the number of gear shifts is greater than this number of gear shifts No, The pressure P _L is used as a parameter to judge the state of deterioration of the fastening performance, and the result of the judgment in S16 is Y
If es is reached and, for example, point A in FIG. 5 is reached, 2-3 shift line change processing is executed in order to reduce the load on the 3-4 clutch 27 in S17, and then the control ends. However, S1
After 5 or even when it is determined No in S16, the control ends.

In the 2-3 shift line changing process in S17, the 2-3 shift up shift line L of the shift map illustrated in FIG. 7 is moved to the low speed side by a predetermined vehicle speed ΔV to perform the 2-3 shift up shift. This is a process of changing to the line M, and this changed 2-3 shift-up shift line M
The information regarding
The shift-up shift is executed based on the 2-3 shift-up shift line M. In the above line pressure learning control and 3-4 clutch load reduction control, the line pressure P _L is set so that the shift time Tc becomes the set shift time To.
Is stored while being updated by learning control, and the line pressure P _{L is} stored.
Since the duty solenoid valve 33 is controlled so as to be 2
Since the shift time c of the -3 shift is always substantially the set shift time To, the responsiveness of the 2-3 shift does not deteriorate. In addition, in addition to the line pressure learning control, the 3-4 clutch load reduction control of S14 to S17 is executed, so that the wear performance of the friction material of the 3-4 clutch 27 causes deterioration of the fastening performance due to long-term durable use. At this stage, the 2-3 shift line is moved to the low speed side to reduce the load on the 3-4 clutch 27. Therefore, for example, as shown by the dotted line in FIG. The number of shifts can be extended from N1 to N2.

FIG. 6 shows a change in the turbine speed Nt and a change in the line pressure P _L during 2-3 shifts. The line pressure P _L before and after the 2-3 shift is started. Is controlled by general line pressure control based on the throttle opening of the engine. In the above embodiment, the case of 2-3 shifts is described as an example, but other shifts (1-2
It is needless to say that the line pressure learning control / clutch / brake load reduction control can also be applied to gear shift, 3-4 gear shift, and various shift down gear shifts.

[Other Embodiments] See FIG. 8. In the 3-4 clutch load reduction control according to this embodiment, when the line pressure learning control is not performed, the shift time Tc is used as a parameter 3-4. The configuration is such that a state in which the engagement performance of the clutch 27 is deteriorated is detected and the same control as the 3-4 clutch load reduction control is performed based on the detected state. Since the control system is the same as that described above, a flow chart of the routine for the 3-4 clutch load reduction control stored in the ROM of the control unit 80 will be described with reference to FIG.

When this control is started at the same time as the start of the 2-3 gear shift, the timer of the soft timer is started (S30), the turbine speed signal is read next (S31), and the turbine speed is then read. Nt is calculated (S
32) Next, it is determined whether or not the 2-3 shift is completed based on the turbine speed Nt (S33). When the shift is not completed, S31 to S33 are repeated, and when the shift is completed, the process proceeds to S34. The shift time Tc is calculated in the same manner as described above, and it is then determined in S35 whether the shift time Tc is smaller than the minimum shift time Tmin stored in the memory while being updated. If Tc <Tmin, the minimum shift time is calculated in S36. The time Tmin is replaced with the current shift time Tc and stored in the memory, and the control after S36 ends.
In this way, the minimum shift time Tmin is updated, and as shown in FIG.
If the number of shifts is greater than or equal to the number of shifts No.
The minimum shift time Tmin corresponding to o is held in the memory. When the result of the determination in S35 is No, S3
7, Tc / Tmin ≧ C (where C is 1.10 to 10)
It is determined whether it is a predetermined value of 1.30).
Before the point A, the determination result in S37 is No, and the control ends.

On the other hand, when the number of shifts increases after a long period of use and reaches, for example, the point A in FIG. 5, the determination result in S37 is Yes, the process proceeds to S38, and 3-4 in S38.
In order to reduce the load on the clutch 27, the 2-3 shift-up shift line changing process similar to that of the above-described embodiment is executed, and then the control ends. Therefore, in the 2-3 shift-up shifts from the next time onward, the 2-3 shift line M is the same as in the above embodiment.
Will be implemented based on. According to the 3-4 clutch load reduction control, as in the case of the above embodiment, 3-
When the state of deterioration of the engagement performance of the 4-clutch 27 becomes a predetermined value or more, the 2-3 shift line is moved to the low speed side to reduce the load of the 3-4 clutch 27.
The durability life of No. 7 can be extended from the number of shifts N1 in FIG. 5 to the number of shifts N2, for example. In this embodiment, 2-3
Although the case of the shift-up has been described, similar to the above-described embodiment, this clutch / brake load reduction control is applied to other shifts (1-2 shift, 3-4 shift, or various shift-down shifts). Of course, can be applied.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an automatic transmission.

FIG. 2 is a configuration diagram of a hydraulic circuit of an automatic transmission.

FIG. 3 is a configuration diagram of a control system of the automatic transmission.

FIG. 4 is a flowchart of a routine for line pressure control and 3-4 clutch load reduction control.

FIG. 5 is a characteristic diagram of a friction coefficient of a friction material of a clutch or a brake.

FIG. 6 is a time chart of turbine rotation speed and line pressure.

FIG. 7 is a diagram showing an example of a shift map.

FIG. 8 is a flowchart of a routine for 3-4 clutch load reduction control of another embodiment.

[Explanation of symbols]

 2 torque converter 10 speed change gear mechanism 13 turbine shaft 20 forward clutch 21 coast clutch 22 first one-way clutch 23 2-4 brake 24 reverse clutch 25 low reverse brake 26 second one-way clutch 27 3-4 clutch 30 hydraulic circuit 33 tuty Solenoid valve 80 Control unit 81 Throttle opening sensor 82 Vehicle speed sensor 83 Engine speed sensor 84 Turbine speed sensor

Claims (4)

[Claims] 1. A torque converter connected to an output shaft of an engine, a speed change gear mechanism connected to an output shaft of the torque converter, a plurality of friction engagement elements for switching power transmission paths of the speed change gear mechanism, and these friction engagements. In an automatic transmission including a plurality of hydraulic actuators for respectively fastening elements, a performance degradation state detection unit that detects a degradation state of frictional fastening performance of the friction fastening element with time; and a performance degradation state detection unit that detects the degradation state. When the lowered state becomes equal to or more than a predetermined value, the physical parameter correlated with the load of the friction engagement element is provided with load adjusting means for adjusting in a direction of reducing the load. Control device. 2. A torque converter connected to an output shaft of an engine, a speed change gear mechanism connected to an output shaft of the torque converter, a plurality of friction engagement elements for switching power transmission paths of the speed change gear mechanism, and these friction engagements. A controller for an automatic transmission, which comprises a plurality of hydraulic actuators for respectively engaging elements and a hydraulic circuit for supplying hydraulic pressure to these hydraulic actuators, and is associated with the frictional engagement performance of frictional engagement elements during gear shifting. In a control device for an automatic transmission provided with a hydraulic pressure correction means for correcting the operating hydraulic pressure of a hydraulic circuit so that a physical parameter approaches its target value, the control device for an automatic transmission is based on the correction amount of the operating hydraulic pressure determined by the hydraulic pressure correction means. A control device for an automatic transmission, comprising: a shift line changing means for changing a shift line related to a shift to a low speed side. 3. The shift line changing means is configured to change the shift line when the increase rate of the working oil pressure with respect to the minimum value of the working oil pressure exceeds a predetermined value. A control device for the automatic transmission described. 4. The performance deterioration state detecting means is configured to detect the state of friction engagement performance deterioration based on the rate of increase in the shift time with respect to the minimum value of the shift time during a shift. The control device for the automatic transmission according to claim 1.