JPH04258561A - Control device for automatic transmission - Google Patents

Abstract

PURPOSE:To change the target speed change time, in a line pressure learning control of an automatic transmission, so as to respond to the change in the frictional coefficient of the friction member of a frictional connection element. CONSTITUTION:An automatic transmission 2 comprises a total traveling distance integrating meter 16 for detecting the quantity of state representing the change in the frictional coefficient of the friction member of a frictional connection element (a), and a target speed change time changing means (e) for lengthening the speed change time at the time when the frictional coefficient is less than a prescribed value longer than a prescribed value. The target speed change time changing means (e) is provided so as to be followed up by a line pressure learning control means (c).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for an automatic transmission, and more particularly to one that performs learning control of hydraulic pressure in consideration of changes in the coefficient of friction of a friction material of a friction engagement element.

0002

[Prior Art] Generally, in an automatic transmission in which gears are changed by a hydraulic actuator that engages and releases frictional engagement elements, the gear shifting time is set to a target value, as disclosed in Japanese Patent Publication No. 63-3183, for example. It is known to perform learning control of hydraulic pressure.

0003

[Problems to be Solved by the Invention] By the way, while the frictional engagement elements of automatic transmissions are generally not used much,
Since the friction material of the friction engagement element is not sufficiently adapted to the mating member, the friction coefficient of the friction material is relatively small. However, since the target value for the gear shift time is set to correspond to when the friction material has sufficiently adapted to the friction coefficient and the friction coefficient is relatively large, if learning control is performed to set the target value when the friction coefficient is relatively small, the predetermined Since a relatively large fastening force is required to ensure the transmitted torque, the hydraulic pressure is corrected to be high. In this case, there is no problem if the correction amount is relatively small, but as it becomes larger, the difference in pressing force between the accumulation pressure chamber and the back pressure chamber of the accumulator also increases. The duration of the shelf pressure formed by this action becomes shorter, and the hydraulic pressure suddenly rises in the middle of the gear shifting process, causing the frictional engagement element to be rapidly engaged and causing a gear shifting shock.

0004

[Means for Solving the Problems] Accordingly, in any of the present inventions, as conceptually shown in FIG.
A target value for the shift time is set, and if the actual shift time differs from the target value, the working oil pressure during the shift of the friction engagement element is adjusted in advance based on at least the engine load so that the actual shift time substantially matches the target value. In an automatic transmission comprising learning control means c for correcting with respect to a set reference value, friction coefficient detection means d for detecting a state quantity indicating a change in the friction coefficient of the friction material of the friction engagement element a; When the friction coefficient of the friction material is below a predetermined value according to the output of the friction coefficient detection means d, the target value of the shift time is set to a longer time than the target value of the shift time when the friction coefficient is larger than the predetermined value. The above-mentioned problem is solved by having a target shift time changing means e.

[0005] In addition to the above-mentioned means, the invention according to the second claim of the present application (hereinafter referred to as the second invention) is characterized in that, in addition to the above-mentioned means, when the friction coefficient of the friction material is less than or equal to a predetermined value, the working oil pressure during gear change of the friction engagement element is The hydraulic pressure changing means f sets the reference value higher when the friction coefficient is larger than a predetermined value. Furthermore, the invention according to the third claim of the present application (hereinafter referred to as the third invention) is a distance accumulating means in which the friction coefficient detecting means accumulates the distance traveled by the automobile.

[0006]

[Operation] In any of the present inventions, when the friction coefficient of the friction material of the friction engagement element is below a predetermined value, the target value of the shift time is set to a longer time than when the friction coefficient is greater than the predetermined value. When the coefficient is less than or equal to a predetermined value, it is possible to suppress an increase in the hydraulic pressure due to the learning control of the shift time.

According to the second aspect of the present invention, in addition to the above-mentioned effect, when the friction coefficient of the friction material is below a predetermined value, the reference value of the working oil pressure during gear shifting of the friction engagement element is set to be lower than when the friction coefficient is greater than the predetermined value. By setting a high value, the hydraulic pressure can be set in anticipation of the amount that needs to be corrected in advance when the friction coefficient is relatively small, and the hydraulic pressure correction width by learning control can be made smaller, making it easier to converge to the target shift time by learning. Responsiveness can be ensured.

Furthermore, according to the third aspect of the invention, the friction coefficient detection means is a mileage accumulating means for accumulating the mileage of the automobile, and the accumulated value of the mileage is correlated with the magnitude of the friction coefficient of the friction material. Therefore, it can be determined whether the friction coefficient of the friction material has reached a predetermined value based on whether the cumulative value of the distance traveled has reached a predetermined value.

[0009]

Embodiments Hereinafter, embodiments of the invention of the present application will be described with reference to the drawings. FIG. 2 shows an overall configuration diagram of the automatic transmission 2 connected to the engine 1 and its control device. As shown in FIG. 2, the output from the engine 1 is transmitted to the automatic transmission 2 via the torque converter 3.

A throttle valve 6 is interposed in an intake passage leading from an air cleaner 4 to an intake manifold 5 of the engine 1, and a throttle opening sensor 7 for detecting the opening of the throttle valve 6 is provided.

The torque converter 3 includes a pump 8 which is rotationally driven by the output from the engine 1, a turbine 9 which is rotationally driven by the drive from the pump 8 via hydraulic oil in the torque converter 3, and a hydraulic oil from the turbine 9. The stator 10 returns to the pump 8 again and is provided with a stator 10 that functions to increase torque, and the turbine 9 is provided with a turbine rotation speed sensor 11 that detects the rotation speed of the turbine 9.

The automatic transmission 2 has a general configuration that includes a planetary gear transmission mechanism in addition to a torque converter 3, and includes a hydraulic pump and a control valve unit 12, which are built-in sources of hydraulic pressure. and a plurality of friction engagement elements such as a multi-disc clutch and a brake used for shifting the planetary gear transmission mechanism and a lock-up clutch that mechanically connects the pump 8 and the turbine 9, and hydraulic pressure for driving and engaging each of these friction engagement elements. The control valve unit 12 includes a line pressure control mechanism that controls line pressure supplied to the hydraulic actuators, and a plurality of shift solenoid valves 13 that control the supply and discharge of line pressure to these hydraulic actuators, respectively. 13 are provided.

The line pressure control mechanism is configured to control line pressure by a duty solenoid valve 14, and is provided with a control unit 15 for controlling the duty solenoid valve 14 and the speed change solenoid valves 13...13. and a mileage totalizer 16 that integrates the signal from the throttle opening sensor 7, the signal from the turbine rotation speed sensor 11, and the distance traveled by the vehicle.
A signal from the control unit 15 is supplied to the control unit 15. Next, a block diagram of the line pressure control mechanism is shown in FIG.

According to FIG. 3, the hydraulic pressure generated by the hydraulic pump P is reduced to a predetermined pressure by a pressure reducing valve 18 through an oil path 17, and an orifice 19 is provided which has a throttling function for this reduced hydraulic pressure. The oil is supplied to the duty solenoid valve 14 through an oil path 20.

By controlling the on-time ratio (duty rate) per cycle of on-off operation in the duty solenoid valve 14, the working oil pressure (duty pressure) in the duty pressure passage 21 is adjusted. Here, as shown in FIG. 4, the higher the duty rate, the lower the duty pressure.

[0016] And this duty solenoid valve 1
The duty pressure adjusted according to the duty rate of 4 is supplied to the line pressure control valve 22 as a pilot pressure. Through this line pressure control valve 22, a part of the working hydraulic pressure is sent to the torque converter 3, and another part is sent to each oil passage 23 to the hydraulic actuator that drives the frictional engagement element for shifting.
, 24. Further, the remainder is discharged to the oil pan of the hydraulic pump P via the oil passage 25. Next, the control unit 15 will be explained.

The control unit 15 is for controlling the automatic transmission 2 via the control valve unit 12, and includes a microcomputer including a CPU, ROM, and RAM, an input/output interface, an A/D converter, and a waveform. Shaping circuit and speed change solenoid valve 13
...13 and a drive circuit for the duty solenoid valve 14.

The ROM of the microcomputer includes:
Based on the turbine rotation speed signal from the turbine rotation speed sensor 11 and the throttle opening signal from the throttle opening sensor 7, a speed change characteristic as shown in FIG. Valve 13...13
A shift control program for controlling the line pressure and a line pressure control program for controlling the line pressure via the duty solenoid valve 14 are stored in advance. This line pressure control control program includes a line pressure learning control program that sets a target value for the shift time and corrects the line pressure so that the actual shift time matches the target value, and The integrated value is set to a predetermined value (100 in this embodiment) based on the signal of the accumulated distance traveled from the mileage totalizer 16.
0 km) or less, a target time changing step sets the target value of the shift time to a longer target value when the integrated value is greater than a predetermined value; and a working oil pressure changing step of setting the line pressure to a higher line pressure when the integrated value is larger than a predetermined value. Here, line pressure control unique to the present application will be explained.

By replacing the target value of the shift time of the automatic transmission 2 with an appropriate value of the change time of the turbine rotation speed as shown by the solid line in FIG. 6, and measuring the change time of the turbine rotation speed, the actual value can be determined. Determine whether the shift time matches the target value. As shown in FIG. 7, a map of correction coefficients corresponding to shifts in shift time is stored in the ROM, and if the shift time does not reach an appropriate value, which is the target value for shift time, correction is made.

[0020] By the way, during a break-in operation in which a new automobile has been driven for only about 1000 km after the start of use, the friction material of the friction engagement element in the automatic transmission 2 is not sufficiently familiar with the sliding contact member of the other party. Therefore, the friction coefficient of the friction material becomes small, and after the break-in period, the friction coefficient becomes large and stable. Figure 8 shows the characteristics of this friction coefficient change over time. During break-in when the total mileage is less than 1000 km, the friction coefficient increases as the total mileage increases, and during the break-in period After the lapse of time, the friction coefficient assumes a larger constant value.

Therefore, in order to prevent shift shock by setting an appropriate shift time during the break-in period and thereafter, the target change time T0 of the turbine rotation speed shown in FIG. 6 is set during the break-in period and thereafter. The line pressure is set to a longer value during the break-in period, and in order to improve the initial response of learning control and achieve the target value of shift time with fewer shifts. As shown in FIG. 9, during the break-in period, the throttle opening is set relatively high as shown in broken line map A, and after the break-in period, as shown in solid line map B. It is set lower than during the break-in period. however,
FIG. 9 shows the line pressure at one gear, and it is assumed that line pressure maps A and B are set for each gear as shown in FIG. Note that the maps shown in FIGS. 4, 7, and 9 are stored in the ROM along with the line pressure control program.

Next, the routines for speed change control and line pressure control will be explained based on the schematic flowcharts shown in FIGS. 10 and 11. Note that Si (i=1, 2, 3...) in the figure indicates each step.

When control is started with the start of the engine 1, various signals from the turbine rotation speed sensor 11, throttle opening sensor 7, and vehicle mileage totalizer 16 are read (S1), and then the current turbine A gear position is calculated based on the rotational speed, throttle opening degree, and the shift characteristic map shown in FIG. 5 (S2). Further, by comparing the currently set gear position stored in the RAM memory with the gear position obtained by the calculation, it is determined whether or not to shift (S3).
, when the result is Yes, it is determined whether the total traveling distance is less than 1000 km (S4), and when the result is No, the process returns to S1. If the result of the determination in S4 is Yes, the target value of the shift time is set to a long value (T0=Ta) (S5A), and the calculated line pressure map A for the gear position is selected (S6
A), and if No, the target value of the shift time is set to a short value (T0=Tb) (S5B), and the calculated line pressure map B for the gear is selected (S6B), and then the memory is The line pressure Pl obtained by the line pressure learning program which will be described later and which is stored in is corrected and updated to the value of [Pl×Ct] (S7). Values modified in this way are used for subsequent control. Next, the duty rate is calculated using map A or B and the map in FIG.
), and a driving current is further output to the speed change solenoid valves 13...13 (S10). After that, the turbine rotation speed is read (S11), and the target turbine rotation speed after the shift is calculated from the turbine rotation speed at the start of the shift (S12).
The actual turbine rotation speed read in Step 11 is compared with the post-shift target rotation speed calculated in S12, and it is determined whether or not the shift has ended (S13). Subsequent steps S14 to S1
6 represents a line pressure learning program, and when the result of the determination in S13 is Yes, the shift time T is calculated (S14
), when the answer is No, the process returns to S1. Next, the difference ΔT between the shift time T and the target value T0 of the shift time set so as to obtain the appropriate turbine rotational speed change shown by the solid line in FIG. 6 is calculated (ΔT=T−T0, T0=Ta, orTb) (S15
). At this time, if it is determined in S4 that the total traveling distance is 1000 km or less (Yes), the target shift time value is lengthened (
T0=Ta), and when it is determined that the total traveling distance is greater than 1000 km (No), the shift time target value is shortened (T0=Tb). Then, in the next step, a map search is performed for a correction coefficient Ct set in a correspondence relationship as shown in FIG. 7 according to the deviation ΔT (S16). In other words, if the deviation ΔT is sufficiently close to 0, the correction coefficient Ct is set to 1, but if the deviation ΔT becomes large in the positive or negative direction and the deviation ΔT is negative (in other words, the broken line in FIG. If the shift time T1 is short (as shown in FIG. 6), the correction coefficient Ct is made small, and if ΔT is positive (that is, if the shift time T2 is long, as shown by the dashed line in FIG. 6), the correction coefficient Ct is made large. Regarding this correction coefficient Ct, when the cumulative value of the total mileage is less than a predetermined value, the correction coefficient Ct is calculated along the characteristic curve shown by the broken line, and when it is larger than the predetermined value, the correction coefficient Ct is calculated according to the characteristic curve shown by the solid line. A correction coefficient Ct is calculated along the curve. This is done by comparing the curve (broken line) when the total traveling distance is 1000 km or less and the curve (solid line) when the total traveling distance is greater than 1000 km, and applying the correction coefficient Ct of the broken line curve when the total traveling distance is 1000 km or less to compensate for the shift time difference. The amount of friction is set to be large, and the friction coefficient of the friction material is set to 100.
This is to correct the shift time to the target value even when the vehicle is below 0 km, in the same way as when the friction coefficient is greater than 1000 km. Next, the process returns to S1 from S16, and the steps after S1 are repeatedly executed.

In the automatic transmission control device described above, a target time changing means and a line pressure changing means are attached to the line pressure learning control means for learning and controlling the line pressure so that the shifting time becomes the target value. By setting a target time longer during the break-in period than after the break-in period, the shift shock can be reduced when the friction coefficient of the friction material of the friction engagement element during the break-in period is relatively small. By preventing this from occurring and increasing the line pressure, it is possible to improve initial responsiveness when performing learning control. It is also conceivable to control the line pressure to be higher than map A when the total travel distance is, for example, 500 km or less.

Further, in this embodiment, the total traveling distance is used as a parameter for switching between map A and map B, but the total driving time or the number of gear changes, which has a certain correlation with the total traveling distance, may also be used as a parameter.

Furthermore, the friction coefficient is indirectly detected by detecting the torque acting on the sliding member on which the friction material slides and the torque of the output shaft of the turbine shaft using a torque sensor or a strain gauge, and the friction coefficient is determined to be a predetermined value. Map A may be used when the value is less than a predetermined value, and map B may be used when the value is greater than a predetermined value. Furthermore, in the present invention, the correction coefficient Ct is added to the line pressure Pl.
However, by calculating the line pressure correction amount ΔPl corresponding to the deviation between the target shift time and the actual shift time,
The line pressure may be corrected by adding it (Pl=Pl+ΔPl).

[0027]

[Effects of the Invention] In any of the present inventions, when the friction coefficient of the friction material of the friction engagement element is below a predetermined value, the target value of the shift time is set to a longer time than when the friction coefficient is greater than the predetermined value. , the increase in hydraulic pressure due to learning control of the shift time is suppressed, the difference in pressing force between the accumulation pressure chamber and the back pressure chamber of the accumulator is suppressed from increasing, and the duration of the shelf pressure is shortened. Shock can be prevented.

According to the second invention, in addition to the above-mentioned effects, when the friction coefficient of the friction material is below a predetermined value, the reference value of the working oil pressure during gear shifting of the friction engagement element is changed to By setting it higher, the hydraulic pressure can be set in anticipation of the amount that needs to be corrected in advance when the friction coefficient is below a predetermined value, ensuring responsiveness in convergence to the target shift time through learning, and relatively low The target shift time can be reached by changing the number of shifts. Furthermore, according to the third aspect of the invention, the friction coefficient detection means is a mileage accumulating means for accumulating the distance traveled by the automobile, and the state of the friction coefficient of the friction material is determined based on this, so the method is relatively simple. The state of the friction coefficient of the friction material can be detected.

[Brief explanation of the drawing]

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

FIG. 2 is an overall configuration diagram of an automatic transmission provided in the engine and its control device.

FIG. 3 is a configuration diagram of a line pressure control mechanism.

FIG. 4 is a diagram showing the relationship between duty rate and duty pressure.

FIG. 5 is a diagram showing shift characteristics.

FIG. 6 is a diagram showing changes in turbine rotation speed during upshifting.

FIG. 7 is a characteristic diagram of a correction coefficient according to a shift time shift.

FIG. 8 is a characteristic diagram of the friction coefficient of a friction material.

FIG. 9 is a diagram showing a map of line pressure.

FIG. 10 is the first half of a schematic flowchart showing a routine for speed change control and line pressure control.

FIG. 11 is the second half of a schematic flowchart showing a routine for speed change control and line pressure control.

[Explanation of symbols] 2... Automatic transmission, 7... Throttle opening sensor, 11... Turbine rotation speed sensor, 12... Control valve unit, 14... Duty solenoid valve, 15... Control unit, 16... Mileage totalizer, 22 …Line pressure control valve.

Claims (3)

[Claims] 1. A hydraulic actuator that controls engagement and release of a frictional engagement element to change gears, and a target value for a gear shifting time, and when the actual gear shifting time differs from the target value, the actual gear shifting time is set to the target value. In the automatic transmission, the automatic transmission is equipped with a learning control means for correcting the working oil pressure during gear shifting of the friction engagement element with respect to a reference value set in advance based on at least the engine load so that the hydraulic pressure of the friction engagement element substantially matches the reference value. Friction coefficient detection means detects a state quantity indicating a change in the friction coefficient of the friction material, and when the friction coefficient of the friction material is less than or equal to a predetermined value, the target value of the shift time is determined by the output of the friction coefficient detection means. From the target value of shift time when the coefficient is larger than the predetermined value,
1. A control device for an automatic transmission, comprising: a target shift time changing means for setting a target shift time to a long time. 2. An operation according to claim 1, further comprising: setting the reference value of the working oil pressure during gear shifting of the friction engagement element higher when the friction coefficient of the friction material is less than a predetermined value than when the friction coefficient is larger than the predetermined value. 1. A control device for an automatic transmission, comprising a hydraulic pressure changing means. 3. A control device for an automatic transmission according to claim 1, wherein the friction coefficient detecting means is a distance accumulating means for accumulating the distance traveled by the automobile.