JPH0544511A - Control device of automatic transmission - Google Patents

Abstract

PURPOSE:To realize countermeasures in consideration of occurrence of such an uncontrollable state as operational abnormality by stopping an engine by way of judging the this uncontrollable state by a second control part in the case when the operational abnormality occurs in a first control part electrically carrying out changeover of a travel range of an automatic transmission. CONSTITUTION:Judgement of whether a range signal (a) from a range selection switch 10 operated by a driver and a detection signal (b) from a range position detector 50 detecting a changeover position of a range changeover valve coincide with each other is constantly carried out by a second control part (an engine control part 24, for example) separately from a first control part 20, and furthermore, a cancel signal (c) dispatched from the first control part 20 is input to this second control part 24. The second control part 24 outputs an engine stop signal when the range signal (a) and the detection signal (b) don't coincide with each other and the cancel signal (c) is not input.

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 that realizes selection of a plurality of driving ranges by electric control.

[0002]

2. Description of the Related Art In an automatic transmission, a traveling range such as a forward range, a reverse range or a neutral range is switched by switching a range switching valve (manual valve). Although the range switching valve is generally switched by manual operation, an automatic transmission having a structure for electrically controlling the range switching valve has already been proposed.

The applicant of the present invention, for example, Japanese Patent Application No. 3-1
It proposes a control device for an automatic transmission as shown in the specification and drawings attached to the application No. 8248. This control device is a neutral setting device that forcibly sets the running range to neutral when the running range is switched against the driver's intention in an automatic transmission that electrically switches the running range. In addition, when the abnormality of the neutral setting device is detected, the engine is stopped.

[0004]

However, assuming a case where a control unit (microcomputer) that electrically switches the traveling range fails or an abnormality occurs in processing, for example, the operating conditions of the neutral setting device are set as follows. Even judgment is impossible. As a result, the running range cannot be forcibly set to neutral or the engine cannot be stopped, and sufficient safety measures must be taken into consideration even when such a software processing abnormality occurs.

As a means for monitoring an abnormality in software processing by a computer, a processing for outputting a signal at a constant time is inserted during the software processing, and it is constantly checked whether or not this signal is output within a designated time. The function of the watchdog timer is known which detects that there is an abnormality in the software processing if no error occurs. However, this function alone cannot monitor all software processing abnormalities. For example, even if the computer is abnormal, the watchdog timer may function normally (sends a signal at fixed time intervals). This watchdog timer function provides sufficient safety measures for the automatic transmission control device. It is difficult to expect.

A technical problem of the present invention is that when a processing abnormality occurs in the first control section that electrically switches the traveling range of the automatic transmission, the second control section determines this when the processing abnormality occurs. By stopping the engine, it is possible to realize safety measures in consideration of the occurrence of such an uncontrollable state.

[0007]

In order to solve the above problems, the control device for an automatic transmission according to the present invention is constructed as follows. That is, an actuator that drives a range switching valve of an automatic transmission, a range selection switch operated by a driver, a range signal output from this switch, and an electric signal corresponding to this signal are output to the actuator. A control device for an automatic transmission, comprising: a first control unit; and a range position detector that detects a range position of the range switching valve and outputs a detection signal to the first control unit. A range signal from the range selection switch, a detection signal from the range position detector, and a cancel signal transmitted from the first control unit during driving of the range switching valve or when an erroneous operation of the range selection switch by a driver is detected. Respectively entered,
A second control unit is provided that determines whether or not the range signal and the detection signal match, and outputs an engine stop signal when both signals do not match and the cancel signal is not input. ..

[0008]

According to the above construction, it is possible to judge whether or not the range signal from the range selection switch and the detection signal from the range position detector coincide with each other by the second control separately from the first control section. It is always done by the department. The cancel signal transmitted from the first control unit is input to the second control unit. Therefore, the second control unit outputs a signal to stop the engine when the range signal and the detection signal do not match and the cancel signal is not input, that is, when the processing abnormality of the first control unit occurs. To stop. As a result, the processing abnormality of the first control unit is more reliably monitored and the safety measures are sufficient.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings. Embodiment 1 FIG. 2 is a perspective view showing an outline of a range switching valve 30 for switching the traveling range of an automatic transmission and its drive mechanism. The range switching valve 30 is of a spool valve type and is supplied with a line hydraulic pressure which is a basic hydraulic pressure for controlling the automatic transmission. By operating the spool of the range switching valve 30 in the axial direction, the discharge port of the range switching valve 30 is switched to control engagement and release of a friction engagement device (not shown) for setting each traveling range.

A worm wheel 42 is fixed on the axis of a control shaft 40 that transmits a driving force to the range switching valve 30. Further, the rotation of the DC motor 34 is transmitted to the control shaft 40 after being decelerated by the engagement between the worm 38 of the drive shaft 36 and the worm wheel 42. And control axis 40
The rotation of moves the spool of the range switching valve 30 in the axial direction via a lever 44 fixed on the shaft. Therefore, the DC motor 34 functions as a kind of actuator that drives the range switching valve 30 to switch the range switching valve 30.

FIG. 1A shows a system diagram of electric control. In this drawing, the range selection switch 10 is a position switch that is switched in response to the driver's operation of the select lever to select the traveling range of the automatic transmission, or an operation switch that is directly operated by the driver.

In FIG. 1 (A), a microcomputer is used as a range control unit 20 (SBW control unit) which is a first control unit, and programs necessary for various software processing for changing the running range of the automatic transmission are stored. Read-only memory (ROM) stored, central processing unit (CPU) for executing this program, writable memory (RA) for temporarily storing variables necessary for the program
It is mainly composed of M).

Similarly, an automatic shift control unit (ECT control unit) 22 and an engine control unit (EF) shown in FIG.
Similarly, the I control unit) 24 is also configured by using a microcomputer. As is well known, the automatic shift control unit 22 controls automatic switching to each shift stage of the automatic transmission based on the vehicle speed and the engine load, and the engine control unit 24 based on the engine speed and the intake air amount. The fuel injection amount from the fuel injection valve (EFI) is controlled.

The range control section 20 receives the range signal a output by operating the range selection switch 10, and the range switching valve 3 corresponding to the range signal a.
An electric signal is output to the DC motor 34 to drive 0. Moreover, the range signal a is simultaneously output to the automatic shift control unit 22 and the engine control unit 24.

A position sensor 50 as a range position detector of the range switching valve 30 is provided on the automatic transmission side. The position sensor 50 detects the switching position of the range switching valve 30, for example, by detecting the rotation angle of the worm wheel 42 as shown in FIG. 2, and outputs the detection signal b thereof to the range control unit 20 and the automatic transmission. It outputs to the control unit 22 and the engine control unit 24, respectively.

The range control unit 20 and the automatic shift control unit 2
2 and the engine control unit 24 respectively, whether or not the range signal a and the detection signal b match, that is, the select range intended by the driver and the actual traveling range of the automatic transmission match. It is determined whether or not there is.
Moreover, in the range control unit 20, the automatic shift control unit 22 and the engine control unit 2 are operated during the switching control of the range switching valve 30 by the DC motor 34 or when the operation of the range selection switch 10 by the driver is obviously wrong.
The cancel signal c is output to the signal No. 4. The apparent erroneous operation of the range selection switch 10 is, for example, a case where the reverse range switch is turned on while the vehicle is traveling forward.

Further, in the range control unit 20 and the automatic shift control unit 22, when the range signal a and the detection signal b do not match and the cancel signal c is not turned on, both control units 20 and 22. Outputs an engine stop request signal d to the engine control unit 24.

FIG. 1B is a flowchart showing the processing contents of the engine control unit 24 (or the automatic shift control unit 22) for monitoring the control of the automatic transmission by the range control unit 20. In step 1 of this drawing, it is determined whether or not the driver's select range L based on the range signal a and the traveling range M of the automatic transmission based on the detection signal b match, and if they do not match. The process proceeds to step 2, and if they match, the process ends. In step 2, it is determined whether or not the cancel signal c output from the range control unit 20 is on, and if the cancel signal c is on, the process ends.

In step 2, the cancel signal c
When it is determined that the switch is not on, the process proceeds to the next step 3, and it is determined whether or not a fixed time has elapsed. If a certain period of time has elapsed, an engine stop signal such as fuel injection cut is issued in step 4. If the fixed time has not elapsed, the process ends. The reason for determining the elapse of a certain period of time in the step 4 is that an instantaneous abnormality due to noise or the like immediately returns to normal, so that it is processed as normal.

As described above, the existing engine control unit 24 is used as the second control unit, and the control of the automatic transmission is also monitored by this, so that the range control unit 20 is temporarily operated.
Even if an abnormality occurs in the processing of the engine control unit 2
The engine is stopped by the process of 4. Further, as the second control unit, in the present embodiment, the automatic shift control unit 22
Since it is also used together, its reliability is further enhanced.

Embodiment 2 FIG. 3 shows an electric system diagram of automatic transmission control in Embodiment 2. In this drawing, a range display device 60 is incorporated in an instrument panel or the like located in front of the driver's seat. Then, as described above, the range control unit 20
Outputs an electric signal to the DC motor 34 according to the range signal a from the range selection switch 10 and also outputs a signal based on the range signal a to the range display device 60. As a result, the range display device 60 lights up the range intended by the driver.

Even if an appropriate electric signal based on the range signal a is output from the range control unit 20 to the DC motor 34, the range switching valve is caused by a failure of the DC motor 34 due to a motor lock, an electric short circuit, a disconnection or the like. There are cases where 30 cannot be controlled. In this case, the range control unit 20 determines that the motor has failed, and outputs a fail signal to the range display device 60 to blink the current running range of the automatic transmission.

However, even when the motor fails, when the range signal a and the detection signal b from the position sensor 50 match, that is, the driver's select range and the running range of the automatic transmission match. When it is, it is not necessary to blink the traveling range on the range display device 60, so this is not performed.

According to the present embodiment, when the DC motor 34 fails and the range intended by the driver is different from the current running range of the automatic transmission, this running range is displayed on the range display device 60 in a blinking manner. Be informed to the driver. Therefore, the driver can travel according to the current range or perform appropriate processing thereafter.

[0025]

As described above, according to the present invention, when a processing abnormality occurs in the first control unit, the second control unit determines the abnormality and stops the engine. Therefore, the processing of the first control unit is performed. Safety measures will be realized in consideration of the inability to control the automatic transmission due to an abnormality.

[Brief description of drawings]

FIG. 1 is a diagram showing an electric control system and a control flowchart of an automatic transmission according to a first embodiment.

FIG. 2 is a perspective view showing an outline of a range switching valve for switching the traveling range of the automatic transmission and its drive mechanism.

FIG. 3 is an electric control system diagram of an automatic transmission according to a second embodiment.

[Explanation of symbols]

 10 Range Selection Switch 20 First Control Section (Range Control Section) 24 Second Control Section (Engine Control Section) 30 Range Switching Valve 34 Actuator (DC Motor) 50 Range Position Detector (Position Sensor)

Claims (1)

[Claims] 1. An actuator for driving a range switching valve of an automatic transmission, a range selection switch operated by a driver, a range signal output from the switch, and an electrical signal corresponding to the signal. A control device for an automatic transmission, comprising: a first control unit that outputs to an actuator; and a range position detector that detects a range position of the range switching valve and outputs a detection signal to the first control unit. There is a range signal from the range selection switch, a detection signal from the range position detector, and the first control unit when the range changeover valve is being driven or when an erroneous operation of the range selection switch by a driver is detected. Cancel signals are input respectively, and it is judged whether or not the range signal and the detection signal match. Control apparatus for an automatic transmission formed by providing a second control unit for outputting a signal of the engine stops when the cancel signal is not inputted.