JPH06235453A - Line pressure control device for automatic transmission - Google Patents

Abstract

PURPOSE:To eliminate response delay of range changeover by detecting a range of setting the vehicle stop state with a range detection means and outputting an indication signal, raising the pressure regulation level of line pressure in selecting a running range with a range selection switch, to a line pressure regulation mechanism. CONSTITUTION:In operating range a range selection switch 1, a range setting valve 2 is actuated on the basis of an outputted electrical signal, so that hydraulic pressure is supplied to a specified position for setting a selected range. In this case, when the range set in an automatic transmission 4 is a range of keeping the vehicle in stop state, such as a parking range, this range is detected by a detection means 5. Then, when the range selected by the range selection switch 1 is a range of running, a signal is outputted to a line pressure control mechanism for raising the line pressure in raising the line pressure regulation level with a control means 6. Consequently, the response of range changeover is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a line pressure in a so-called shift-by-wire automatic transmission in which a range setting valve is switched by an electric signal based on a switch operation.

[0002]

2. Description of the Related Art A general automatic transmission for a vehicle is constructed such that each gear for forward traveling is automatically set based on the vehicle speed, throttle opening, etc. The parking or neutral state for maintaining the state, the setting of the reverse gear or the forward gear where the engine brake works, and the like are performed based on the manual operation of the driver. Conventionally, a mechanism for selecting the range has a structure in which a shift lever provided in a driver's seat and a manual valve of a valve body of an automatic transmission are connected via a cable and a link mechanism.

On the other hand, recently, the reliability of various electric control devices has become higher and the cost thereof has been lowered, so that not only the setting of the shift speed but also the selection of the range is performed electrically. It is becoming more and more through means. One example thereof is described in JP-A-61-278647. The device described in this publication uses a rotary valve as a shift valve for selecting a range, and drives a motor by a command signal from a controller based on operating a shift switch. The spool of the rotary valve is rotated to switch the oil passage for sending the hydraulic pressure.

Further, the device described in this publication is equipped with a pressure control valve for alleviating a shock caused by sudden engagement of the friction engagement device. That is, when the rotary valve is switched to set the travel range, the hydraulic pressure supplied to the friction engagement device to be engaged in the travel range is adjusted to a relatively low engagement start hydraulic pressure by the pressure control valve. After that, the pressure is gradually increased to the complete engagement hydraulic pressure.

[0005]

In the so-called shift-by-wire automatic transmission that switches the range based on the above-mentioned electric signal, the driver is required to operate only the switch for switching the range. Therefore, the operation performed by the driver is extremely simple. However, in order to actually switch the range, the motor is energized to generate a predetermined torque, which causes the rotary valve to rotate, and as a result, after the oil passage is switched, the oil pressure is changed via that oil passage. Must be supplied to a given friction engagement device. Therefore, the difference between the operation required by the driver and the actual range switching operation due to the operation of each mechanism becomes large, and this is felt as a response delay.

That is, in the case of the conventional device for switching the range by operating the lever, the switching operation of the driver is transmitted to the manual valve as it is, and the manual operation and the operation of the manual valve coincide with each other, so that the response is delayed. There was almost no feeling, but in the shift-by-wire automatic transmission, contrary to the reduction of driver's operation, an actuator such as a motor is newly interposed between the valve and the valve for range switching. Therefore, there is a lot of room for amplifying the response delay of the range switching.

Further, in the device described in the above-mentioned publication, after the rotary valve is switched, the engagement hydraulic pressure is gradually increased from the engagement start hydraulic pressure to the complete engagement hydraulic pressure. Therefore, the traveling range is set. The friction engagement device that is engaged as much as possible has a long time until it has the torque capacity required for setting the traveling range,
This has the disadvantage of further increasing the response delay of range switching.

The present invention has been made in view of the above circumstances, and provides a line pressure control device capable of eliminating a response delay in range switching when setting a traveling range in a shift-by-wire automatic transmission. That is the purpose.

[0009]

The present invention is characterized in that it has the structure shown in FIG. 1 in order to achieve the above object. That is, according to the present invention, the range setting valve 2 that operates based on an electric signal by operating the range selection switch 1 to switch the hydraulic pressure supply path for setting the range, and the line pressure adjusting level are electrically controlled. In a line pressure control device of an automatic transmission 4 including a line pressure adjusting mechanism 3 that changes based on a signal, a range detecting means 5 for detecting a range set in the automatic transmission 4.
When the range for setting the vehicle stop state is detected by the range detection means 5 and the range for traveling is selected by the range selection switch 1, the instruction signal for increasing the line pressure adjustment level is issued. The control means 6 for outputting to the line pressure adjusting mechanism 3 is provided.

[0010]

The range of the automatic transmission to which the present invention is applied is
It is set by operating the range selection switch 1. That is, the range setting valve 2 is operated based on the electric signal output by operating the range selection switch 1.
Operates to supply hydraulic pressure to a predetermined location so as to set the selected range. In that case, if the range set in the automatic transmission is a range such as a parking range that keeps the vehicle stopped, this range is detected by the range detection means 5 and the range selected by the range selection switch 1 is determined. If it is in the range for traveling, the control means 6 outputs a signal for increasing the line pressure adjusting level to increase the line pressure to the line pressure control mechanism 3. Therefore, when the range for maintaining the stopped state is switched to the running range, the hydraulic pressure is quickly supplied to the friction engagement device for setting the running range, and the range setting valve 2 is switched to set the running range. At that time, a high line pressure is supplied to the friction engagement device for setting the traveling range, and this is immediately engaged, so that the selected traveling range is quickly set. That is, the hydraulic pressure is quickly supplied so as to cover the response delay in the mechanism.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 2 is a block diagram showing an embodiment of the present invention. An automatic transmission 11 connected to an engine 10 is a so-called shift-by-wire automatic transmission, and a manual valve 12 for setting a range has a motor. An actuator 13 such as
By this, the manual valve 12 is switched and set to a predetermined range. The manual valve 12 may be a conventional type in which a spool is linearly moved or a rotary valve described in the above-mentioned publication. Further, the actuator 13 may be anything that operates based on an electric signal,
Other than a motor can also be used.

An electronic control unit (hereinafter, SBW, for example) for controlling the actuator 13 to set the selected range.
-Referred to as ECU) 14 is provided. This SBW-
The ECU 14 is mainly composed of a microcomputer, and is connected with a range selection switch 15 manually operated by a driver and a range sensor 16 for detecting a range actually set in the automatic transmission 11. . The range sensor 16 detects whether or not the traveling range is set based on the supply / discharge state of the hydraulic pressure to a predetermined oil passage or the friction engagement device, and a hydraulic switch can be used as an example. .

The automatic transmission 11 shown in the figure is constructed so as to increase the line pressure in accordance with the throttle opening. As a means therefor, the linear solenoid valve 1 is used.
7 is provided. This linear solenoid valve 17
Is a part of the line pressure regulating mechanism. As the line pressure regulating mechanism, for example, the hydraulic pressure generated by the hydraulic pump and the hydraulic pressure regulated by the linear solenoid valve 17 are connected to the spool. A mechanism configured to generate the pressure set by the linear solenoid valve 17 by sandwiching and opposing can be adopted.

As means for controlling the linear solenoid valve 17, an electronic control unit for an automatic transmission (hereinafter, tentatively referred to as ECT-ECU) 18 is provided. The detection signal from the throttle opening sensor 19 and the detection signal from the range sensor 16 are input to the ECT-ECU 18, and the control range signal from the SBW-ECU 14, that is, the range signal selected by the range selection switch 16. Has been entered.

Next, the operation of the above-mentioned device will be described. FIG. 3 is a flowchart showing a line pressure control routine by the above-mentioned device. In step 1, the range set by the automatic transmission 11 is a range for stopping the vehicle, that is, a parking (P) range or a neutral (N) range. Judge whether it is a range. This judgment can be made based on the detection signal of the range sensor 16.
If the determination result is “yes”, the control range in step 2, that is, the range selected by the range selection switch 15 is the range for traveling, that is, the range for forward traveling (D range, “2” range, L range). Range) or reverse (R) range.
This determination can be made by the control range signal being transmitted from the SBW-ECU 14 to the ECT-ECU 18. If the determination result is "yes", control is performed to increase the line pressure to a predetermined pressure (step 3). This is a control for preventing the delay of the engagement of the friction engagement device that sets the range for the traveling, and therefore the set pressure of the line pressure is
It is set to a high value within a range in which the shock due to the engagement of the friction engagement device does not become excessive. Further, the hydraulic pressure supply speed becomes slower as the viscosity is higher, and the line pressure is increased as the throttle opening is larger. Therefore, the target set pressure in step 3 may be changed according to the oil temperature and the throttle opening.

A drive signal is output to the actuator 13 simultaneously with the output of the command signal for the line pressure boosting control.
Since there is a delay in the operation of the manual valve 12 and the supply of the hydraulic pressure to the predetermined friction engagement device for setting the traveling range, in step 4 following step 3, the actual range of the automatic transmission 11 is set for traveling. It is determined whether the range has been switched to. If the range of the automatic transmission 11 has not been switched to the range for traveling due to the response delay, that is, if the result of the determination in step 4 is "no", the control process returns and the automatic transmission 11 is also returned. When the range is switched to the range for traveling, that is, when the determination result in step 4 is "yes", the process proceeds to step 5 and the timer T is started. Counting is continued until the count value reaches a predetermined time α.

This time α is the time required for the oil to fill until just before the piston of the hydraulic servo in the friction engagement device for setting the traveling range moves, and after the time α has passed, that is, in step If the result of the determination in 6 is "yes", line pressure return control for reducing the line pressure to the normal pressure is executed in order to prevent the frictional engagement device from suddenly engaging (step 7). ). Note that the time α may be a time that is changed based on a parameter related to the oil pressure supply / discharge speed such as the oil temperature, instead of the preset fixed time.

On the other hand, if the determination result of step 1 or step 2 is "no", that is, if the range set in the automatic transmission 11 or the control range is the range for forward or reverse, Normal line pressure control is performed (step 8).

The time chart of the change of the line pressure in the above-mentioned control is shown in FIG. 4, and when the shift to the running range is performed at the time t1, the line pressure increase control is executed at the same time. . Then automatic transmission 11
The range is switched to the running range at time t2, and control is performed to reduce the line pressure to the normal pressure at time t3 when a predetermined time α has elapsed from this time point. As a result, the time until the engagement of the friction engagement device is shortened, and the engagement of the friction engagement device is performed by the normal line pressure, so that the shift shock does not increase.

Therefore, in the above-described automatic transmission 11 for performing the line pressure control, when shifting from the parking range or the neutral range to the driving range such as the driving range, the line pressure is output simultaneously with the output of the shift instruction signal. Since it is increased, the delay time until the engagement of the friction engagement device for setting the traveling range is shortened, and as a result, the response of range switching is improved.

[0021]

As described above, according to the present invention,
Even in an automatic transmission in which a manual valve for setting a range is driven by an actuator that operates based on an electric signal, the line pressure is increased when switching from a range in which a stopped state is maintained to a range for running. The time until the frictional engagement device for setting the traveling range is engaged can be shortened, and as a result, the responsiveness of switching to the traveling range is improved and the shift feeling is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of the present invention.

FIG. 2 is a block diagram for explaining an embodiment of the present invention.

FIG. 3 is a flowchart showing a line pressure control routine by the device of the present invention.

FIG. 4 is a time chart showing changes in line pressure during line pressure control by the apparatus of the present invention.

[Explanation of symbols]

 1 range selection switch 2 range setting valve 3 line pressure adjusting mechanism 4 automatic transmission 5 range detecting means 6 control means

Claims (1)

[Claims] 1. A range setting valve that operates on the basis of an electric signal by operating a range selection switch to switch a hydraulic pressure supply path for setting a range, and a line pressure adjusting level as an electric signal. In a line pressure control device for an automatic transmission including a line pressure adjusting mechanism that changes based on the above, a range detecting means for detecting a range set in the automatic transmission, and a range for setting a vehicle stop state are And a control means for outputting to the line pressure regulating mechanism an instruction signal for increasing the regulation level of the line pressure when the range is detected by the range detecting means and the range for selecting is selected by the range selection switch. A line pressure control device for an automatic transmission, which is characterized in that