JPH04159139A - Vehicular automatic transmission control method - Google Patents

Abstract

PURPOSE:To maintain travel performance and prevent the durability of friction engaging means from being lowered by maintaining line pressure high in the case of a slip being generated to the friction engaging means, and lowering engine output when the slip of the friction engaging means is still uncorrected. CONSTITUTION:An automatic transmission 1 is provided with a speed change gear formed of planetary gear mechanism 2 and plural friction engaging means 3, and the input shaft thereof is connected to an engine 5 through a torque converter 4. The hydraulic control device 6 of the automatic transmission 1 is controlled by an electronic control unit 7 for an automatic transmission on the basis of signals from a sensor 9 for detecting the rotating speed of the automatic transmission 1 and a sensor 10 for detecting the rotating speed of the torque converter 4. When nonconformity between the reference rotated state and actual rotated state of either one of the friction engaging means 3 exceeds the allowed limit, oil pressure for engaging this friction engaging means 3 is built up. When this nonconformity still exceeds the allowed limit even with oil pressure buildup, the output of the engine 5 is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an automatic transmission in which a plurality of gears are set by engaging frictional engagement means using hydraulic pressure, and a method for controlling an engine by connecting the automatic transmission. It is something.

Conventional Technology As is well known, automatic transmissions installed in vehicles such as automobiles use multiple frictional engagement means such as clutches and brakes as appropriate for the power transmission path in a gear train mainly consisting of a planetary gear mechanism. By engaging and releasing the gears, a plurality of gears having different gear ratios can be set.

FIG. 4 is a conceptual diagram thereof, and the automatic transmission 1 includes the above-mentioned planetary gear mechanism 2 and frictional engagement means 3, and is connected to an engine 5 via a torque converter 4. The frictional engagement means 3 is engaged by hydraulic pressure, and switching between engagement and disengagement is performed by hydraulic pressure, and a hydraulic control device 6 for this purpose is provided. This hydraulic control device 6 also has a widely known configuration,
The line oil pressure that engages the frictional engagement means 3 and serves as the basic oil pressure for various controls is regulated according to the throttle opening θ of the engine 5, and is also adjusted based on the throttle opening θ and the vehicle speed V. Gears are changed by operating a shift valve (not shown). In the example shown in Figure 4,
Such pressure regulation and shifting are controlled by an electronic control unit (A-ECU) 7 for automatic transmission.

As mentioned above, the line oil pressure is regulated according to the throttle opening θ, so as the engine output increases, the torque transmission capacity of the friction engagement means 3 increases, making it possible to transmit the necessary torque. .

However, if an abnormality such as stick occurs in the primary regulator valve that regulates the line oil pressure, or in the solenoid valve or throttle valve that sends a signal pressure corresponding to the throttle opening θ to the primary regulator valve, it becomes impossible to obtain the necessary and sufficient line oil pressure. A decrease in line oil pressure causes a slip in the frictional engagement means and a corresponding decrease in the durability of the frictional engagement means. A method is adopted in which the rotational speed of the rotating members on the side and downstream sides is detected, and when the rotational speed exceeds the permissible limit, the output of the engine is reduced. To explain this using the system shown in FIG. A signal is output to the electronic control unit (ECU) 8, and the throttle opening θ of the engine 5 is reduced by the electronic control unit 8.

Problems to be Solved by the Invention According to the method disclosed in Japanese Patent Application No. 1-236604 mentioned above, the torque applied to the frictional engagement means that is slipping is reduced to the torque that is permissible for the frictional engagement means. Therefore, it is possible to prevent slippage and the resulting decrease in durability.

However, if slippage occurs in the friction engagement means, the torque for driving the vehicle becomes smaller than the torque that should originally be obtained, and the driving performance (acceleration) deteriorates. Since the engine output is reduced to the torque allowed by the frictional engagement means where the frictional engagement means is generated, driving performance cannot be improved even if the frictional engagement means no longer slips.

In addition, it may be possible to adjust the line oil pressure based on requirements other than the throttle opening, and if the above-mentioned engine output reduction control is performed in such a case, the driving performance will be unnecessarily deteriorated.

This invention was made in view of the above circumstances, and an object of the present invention is to provide a control method that can maintain running performance as much as possible and prevent a decrease in durability of frictional engagement means. It is.

Means for Solving the Problems In order to achieve the above object, the method of the present invention first engages the frictional engagement means when a situation that is considered to be caused by slippage of the frictional engagement means occurs. Increase the oil pressure of
The present invention is characterized in that if the above-mentioned situation is not corrected even with this increase in oil pressure, the engine output is reduced.

More specifically, the present invention provides a plurality of gears with different gear ratios depending on the engagement and release states of a plurality of frictional engagement means engaged by hydraulic pressure, and transmits engine power to the wheels. In a vehicle automatic transmission that transmits power to a user, the reference rotation is determined based on the rotational state of either the member on the upstream side or the member on the downstream side in the power transmission direction with respect to any frictional engagement means. When l1llllj between the state and the actual rotational state of the other member exceeds a predetermined allowable limit, the hydraulic pressure for engaging one of the frictional engagement means is increased, and the increase in the hydraulic pressure also causes the actual rotational state to increase. This method is characterized in that the output of the engine is reduced when a combination of a rotational state and a reference rotational state exceeds a predetermined allowable limit.

Function: The automatic transmission targeted by this invention has a plurality of frictional engagement means that are engaged by hydraulic pressure, and by engaging any one of them, the transmission from the upstream member to the downstream member is caused. Power is transmitted to the member. Note that if the friction engagement means is a brake, the upstream member is a fixed member such as a housing, and this fixed member applies a reaction force to the downstream fixed member to fix the downstream member. Become.

By the way, in an automatic transmission, the original rotational state of each rotating member is determined according to the gear position set by engaging a predetermined frictional engagement means. In other words, if the actual rotational state of any rotating member is known, the rotational states of other members that cause that rotational state are also uniquely determined. Therefore, the present invention determines a reference rotational state based on the rotational state of any of the rotating members, and when one saw in the actual rotational state exceeds the allowable limit, the hydraulic pressure for engaging the frictional engagement means is increased. Therefore, the actual rotation state approaches the reference rotation state. If IB in these rotational states falls within the permissible limits, the oil pressure is maintained at the same pressure.

Further, even if the oil pressure is increased, the engine output is reduced only when the difference between the actual rotation state and the reference rotation state does not fall within the allowable limit. As a result, the torque applied to the frictional engagement means that is slipping is reduced, so that the slippage is corrected.

Example Next, the method of the present invention will be explained based on examples.

The automatic transmission targeted in the examples described below is of a type that can regulate line oil pressure based on information other than throttle opening, and the engine is of a type whose output can be changed by means other than the accelerator pedal. It is something.

FIG. 2 is a conceptual diagram showing an example of the automatic transmission 1.
is equipped with a gear transmission consisting of a gear train mainly consisting of a planetary gear mechanism 2 and a plurality of frictional engagement means 3 such as clutches and brakes that change the power transmission path in this gear train. (not shown) is connected to an engine 5 via a torque converter 4. An example of the gear transmission device is the one described in the specification and drawings attached to the above-mentioned Japanese Patent Application No. 1-236604.

The automatic transmission 1 further includes a hydraulic control device 6 that adjusts the hydraulic pressure generated by the hydraulic pump to a predetermined line hydraulic pressure and switches the frictional engagement means 3 to perform gear shifting. A solenoid valve in a hydraulic control device 6 is operated by an output signal from an aircraft electronic control unit (A-ECU) 7. This electronic control device 7 receives signals such as the throttle opening θ and the vehicle speed ■, as well as the rotational speed No. of the output shaft (not shown) of the automatic transmission 1.
, a signal from a sensor 10 that detects the rotation speed NT+ of a turbine runner (not shown) in the torque converter 4, a signal from a shift position sensor, a water temperature sensor (each not shown), etc. It has been entered.

Then, the electronic control device 7 outputs a signal S1 for adjusting the line oil pressure according to the calculation results based on these input data.
A signal S2 for shifting is output to the hydraulic control device 6, and a signal S3 for reducing engine output is output to the engine electronic control device [8]. Further, the engine electronic control device 8 sends a signal S3 for reducing engine output.
The throttle opening degree θ is reduced by inputting .

Here, an example of a hydraulic circuit for regulating the line hydraulic pressure based on the output signal S1 from the electronic control device 7 is shown in FIG. 3.

The line hydraulic control valve 20 includes a first spool 21, a second spool 22, and a coil spring 23 disposed between them, and a discharge port of a hydraulic pump 24 is connected to an input port 25 and a feedback boat 26. ing. In addition,
Reference numeral 27 is an orifice. Therefore, when hydraulic pressure is applied to the feedback boat 26 and the force pushing the first spool 21 downward in the figure increases, the first spool 21
moves downward to connect input port 25 and output port 28. In this state, the force pushing up the first spool 21 increases, so the first spool 21 rises and cuts off communication between the input port 25 and the output port 28.

That is, a hydraulic pressure balanced with the force pushing up the first spool 21 is generated in the line hydraulic oil passage 29.

On the other hand, the second spool 22 has two lands, a reverse boost boat 30 is opened in the middle of these lands, and a control signal boat 31 is opened in the lower end. A duty control solenoid valve 32 is connected to this control signal boat 31, and the duty control solenoid valve 32 closes the drain boat when it is in the OFF state and opens the drain boat when it is in the ON state. The pressure applied to the control signal boat 31 is controlled.

That is, in the line hydraulic control valve 20, the control signal boat 3
The larger the pressure applied to the first spool 21, the greater the force pushing up the first spool 21, so the line oil pressure generated in the line oil pressure oil passage 29 becomes higher.

Also, to explain a device for electrically controlling the throttle opening θ, this type of device inputs the amount of depression of the accelerator pedal into the engine electronic control device 8, and also controls engine temperature, outside air temperature, automatic gear change. The accelerator pedal depression amount data is corrected based on data such as the gear position of the machine, and based on the result, a motor connected to the throttle valve is driven, and the output of the opening sensor is controlled by the electronic control device 8. By inputting , it is possible to adopt a device that performs feedback control of the throttle opening.

The method of the present invention, which is intended for the above-mentioned automatic transmission 1 and engine 5, will now be described.

FIG. 1 is a flowchart showing the routine of the control method. First, in step 1, the turbine rotational speed NTs is calculated as a reference rotational state to be used as a criterion. This is the rotational speed No. of the output shaft, which is a downstream member of the frictional engagement means 3.
The turbine rotation speed NT+ which should be the output shaft rotation speed NO when there is no slippage in the frictional engagement means 3 is determined. The calculation is as follows: If the gear ratio of automatic transmission 1 is r, then NTI=r・N.

This is done using the formula:

In step 2, it is determined whether the flag F1 is "1". This flag F1 is a flag indicating that the slippage of the frictional engagement means is judged and the control to correct it is being carried out, and if it is 1", it indicates that the control is being executed.
If it is "0", it indicates that it is not being executed. Therefore, at the start of this control, the flag F1 is "0", and the determination result in step 2 is "no", and the process proceeds to step 3.

In step 3, the difference between the actual rotation speed NT+ of the turbine launch detected by the sensor 10 described above and the rotation speed NTs determined in step 1 is set to a predetermined first set value N1.
Determine whether or not the above is true. This first set value Na indicates the allowable limit of one gloss between the actual rotation speed of the turbine runner and the reference rotation speed, and the difference between these rotation speeds is the first set value N.
If it is less than 1, that is, if the judgment result in step 3 is "No", the control step returns.Also, if the difference in the rotation speed is greater than or equal to the first set value N!, step 3
If the judgment result is "1 yes", the process proceeds to step 4, where the flag Fl is set to "1", and then, in step 5, the duty ratio is decreased by a predetermined value β (D-β).

This duty ratio is the ratio between the ON state and the OFF state of the duty control solenoid valve 32 shown in FIG. Lower the duty ratio and increase the OFF state ratio. As a result, the oil pressure applied to the control signal boat 31 of the line oil pressure control valve 20 becomes higher, so the pressure regulation level by the line oil pressure control valve 20 becomes higher, and the line oil pressure increases. Therefore, the hydraulic pressure for engaging the frictional engagement means 3 becomes higher, so that the slippage of the frictional engagement means 3 that has been slipping is reduced or eliminated.

In step 6 following step 5, it is determined whether the duty ratio after the change is "0". That is, it is determined whether the duty control solenoid valve 32 is completely OFF and the oil pressure applied to the control signal port 31 of the line oil pressure control valve 20 cannot be increased any higher. Since the degree to which the duty ratio is reduced by one control, that is, the predetermined value β described above, is a relatively small value, the first
In the control of Step 5 for the second time, the duty ratio does not become "0", so the first judgment in Step 6 is "No", and the control process returns.

Returning to step 1, the turbine rotation speed NTs is calculated based on the output shaft rotation speed NO after changing the duty ratio, and then the process proceeds to step 2, but the flag F1 is set to "1" in the previous step 4. Therefore, the judgment result in step 2 is "yes" and the process proceeds to step 7.

In step 7, the turbine rotation speed N obtained by calculation is
The difference between Ts and the actual rotational speed NTt of the turbine launch detected by the sensor 10 is determined, and it is determined whether the difference is less than or equal to the second set value Nb.

Note that here, the second set value NbO value is set as the above-mentioned first set value Na.
The reason for this difference is to prevent /% cinching. Even if the duty ratio is reduced and the line oil pressure is increased in step 51, if slippage occurs in the frictional engagement means, the difference in rotational speed will not become less than the second set value Nb. The determination result in step 7 is "no".

In this case, the process advances to step 8 and it is determined whether the flag F2 is "1". This flag F2 is to indicate that the line oil pressure is at the highest pressure, and if the judgment result in step 6 is "no", it is set to "0", so in this case The determination result in step 8 is "no" and the control process proceeds to step 5.

Then, the line oil pressure is further increased by decreasing the duty ratio by the predetermined value β again, and then in step 6 it is determined whether the duty ratio is "0" or not.

As a result of performing the process from step 1 to step 8 above, the duty ratio becomes "0" and the line oil pressure is increased to the maximum pressure, the judgment result in step 6 becomes "yes" and the process goes to step 9. Then, the flag F2 is set to "1".

With the line oil pressure raised to the maximum pressure, the calculated turbine rotation speed NTs and the measured turbine rotation speed NT+
If the difference between the two and The process returns.

Also, even if the line oil pressure is increased to the maximum pressure, the calculated turbine rotation speed NTs and the actually measured turbine rotation speed NT+
If the difference is not equal to or less than the second set value Nb, the judgment result in step 8 becomes "yes", and the process proceeds to the step entrance where the throttle opening degree θ is reduced by the predetermined value α. In other words, only when the slippage of the friction engagement means cannot be corrected by increasing the line oil pressure can the throttle opening θ be changed.
throttle to reduce engine output. This is done by outputting a signal from the engine electronic control unit 8.

The control process returns after reducing the throttle opening θ by the predetermined value α, so step 1 and step 2 are performed again.
After that, the decision in step 7 is made. If the slippage of the friction engagement means is corrected by reducing the engine output by reducing the throttle opening θ, the difference between the calculated turbine rotation speed NT+ and the actually measured turbine rotation speed NT+ is set as the second setting. Since it is equal to or less than the value Nb, the determination result in step 7 becomes "yes". On the other hand, if the frictional engagement means still slips, the calculated turbine rotation speed NTs
The difference between this and the actually measured turbine rotation speed NTr is the second set value N
If it is not equal to or less than b, the result of the determination in step 7 becomes "no", and the control in step 11 is performed via step 8. That is, the throttle opening degree θ is reduced by the predetermined value α again.

The difference between the turbine rotation speed NTs calculated in this manner and the actually measured turbine rotation speed NT+ is the second set value Nb.
The engine output is reduced by gradually reducing the throttle opening θ until the frictional engagement means becomes below, that is, until there is almost no slippage of the frictional engagement means.

As described above, in the control method of the present invention, when slippage occurs in the frictional engagement means, the line oil pressure is increased to correct the slippage of the frictional engagement means, so that the torque for running does not decrease. Deterioration of driving performance (acceleration) can be prevented. Furthermore, if it is not possible to prevent the frictional engagement means from slipping by increasing the line oil pressure, the engine output is reduced to stop the frictional engagement means from slipping, thereby preventing a decrease in the durability of the frictional engagement means. be able to.

In addition, in the above embodiment, when it is determined that slippage has occurred in the frictional engagement means, the line oil pressure is not immediately raised to the maximum pressure, but is increased in stages, so the line oil pressure is increased unnecessarily. It is possible to prevent deterioration of fuel efficiency due to this.

Furthermore, in the configuration shown in FIG. 2, the line oil pressure is set to the highest pressure when the duty control solenoid valve 32 is completely turned off. Even if the vehicle runs out, the engagement pressure of the frictional engagement means can be maintained and the vehicle can travel.

In the embodiment described above, the turbine rotation speed calculated from the output shaft rotation speed and the gear ratio was used as the reference rotation speed, but the present invention is not limited to the above embodiment, and the rotation used as the reference for judgment is , various types can be adopted as necessary.

As described in detail, in the method of the present invention, when it is determined that the friction engagement means is slipping, the line oil pressure is first increased as high as possible, thereby preventing the friction engagement means from slipping. is corrected, and the degree to which deterioration in driving performance (acceleration) is prevented is higher than ever before. Furthermore, if the slippage of the frictional engagement means is not corrected by increasing the line oil pressure, the engine output is reduced to correct the slippage of the frictional engagement means, thereby preventing a decrease in the durability of the frictional engagement means. I can do it.

[Brief Description of the Drawings] Fig. 1 is a flowchart for explaining an example of the method of the present invention, Fig. 2 is a conceptual diagram of a drive system including the target automatic transmission, and Fig. 3 is a flowchart for explaining an example of the method of the present invention. FIG. 4 is a conceptual diagram of a control system of a general automatic transmission. 1... Automatic transmission, 2... Planetary gear mechanism, 3.
...Frictional engagement means, 4...Torque converter, '
5...Engine, 6...Hydraulic control device, 7...
・Electronic control device for automatic transmission, 8...Electronic control device for engine! , 9.10...Sensor, 2o...Line oil pressure control valve, 32...Duty control solenoid valve. Applicant Toyota Motor Corporation Representative Patent Attorney Takeshi Watanabe Mistakes Figure 4

Claims (1)

[Scope of Claims] A vehicle that transmits engine power to wheels by setting a plurality of gears with different gear ratios depending on the engagement and release states of a plurality of hydraulically engaged friction engagement means. In automatic transmissions, there is a reference rotational state determined based on the rotational state of either the upstream member or the downstream member in the power transmission direction with respect to any frictional engagement means, and the other member's rotational state. When the discrepancy with the actual rotational state of the member exceeds a predetermined allowable limit, the hydraulic pressure for engaging any of the frictional engagement means is increased, and the increase in the hydraulic pressure also causes the discrepancy between the actual rotational state and the standard. A method for controlling an automatic transmission for a vehicle, characterized in that the output of the engine is reduced when a discrepancy with a rotational state exceeds a predetermined allowable limit.