JP2903794B2 - Control device for automatic transmission - Google Patents

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 which realizes selection of a plurality of travel ranges by electrical 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 configuration in which the switching is performed by electrical control has already been proposed.

[0003] The applicant of the present invention also discloses, for example, Japanese Patent Application No. 3-1.
A control device for an automatic transmission is proposed as shown in the specification and the drawings attached to the application No. 8248. This control device includes a neutral setter that forcibly sets the traveling range to neutral when the traveling range is switched against the driver's intention in the automatic transmission that performs the switching of the traveling range by electrical control. When the abnormality of the neutral setting device is detected, the engine is stopped.

[0004]

However, assuming that a control unit (microcomputer) that electrically switches the travel range or a processing error occurs, for example, the operating condition of the neutral setting device is determined. It is impossible to even judge. As a result, neither the driving range can be forcibly set to neutral or the engine cannot be stopped, and sufficient safety measures must be taken in consideration of the case where such software processing abnormality occurs.

[0005] As means for monitoring an abnormality in software processing by a computer, a process of outputting a signal at regular time intervals during the software processing is performed, and it is always checked whether or not this signal is output within a designated time. A watchdog timer function is known that detects that there is an abnormality in software processing if no error occurs. However, this function alone cannot monitor all software processing abnormalities. For example, even if there is an abnormality in the computer, the watchdog timer may function normally (transmit a signal at regular intervals), and this watchdog timer function provides sufficient safety measures for the control device of the automatic transmission. It is difficult to expect.

A technical problem of the present invention is that, when a processing abnormality occurs in a first control unit which electrically switches a traveling range of an automatic transmission, the second control unit determines the abnormality. By stopping the engine, it is necessary to realize a safety measure that also takes into consideration the occurrence of such an uncontrollable state.

[0007]

SUMMARY OF THE INVENTION The present invention provides an actuator for driving a range switching valve of an automatic transmission, a range selection switch operated by a driver, and a range position detector for detecting a range position of the range switching valve. And a first control unit that outputs an electric signal corresponding to a range signal output from the range selection switch to the actuator, and a second control unit different from the control unit. The control device, wherein the first control unit and the second control unit individually receive the range signal and the detection signal from the range position detector, and check whether these two signals match. The second control unit determines whether the range control valve is being driven or when the driver detects an erroneous operation of the range selection switch. When receiving the cell signal, the range signal and the detection signal do not match, and when there is no input of the cancel signal, it is configured to determine that the processing of the first control unit is abnormal and output a signal of engine stop. I have.

[0008]

As described above, according to the present invention, both the first control unit and the second control unit determine whether the range signal from the range selection switch matches the range position detection signal. The second control unit determines the processing abnormality of the first control unit and outputs a signal to stop the engine, so that even if the first control unit itself fails, the fail-safe function is used. Can be maintained and sufficient safety measures can be implemented.

[0009]

Next, an embodiment of the present invention will 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 a traveling range of an automatic transmission and a driving mechanism thereof. The range switching valve 30 is of a spool valve type, and is supplied with a line hydraulic pressure serving as 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 thereof is switched, and the engagement and release of a friction engagement device (not shown) for setting each traveling range is controlled.

A worm wheel 42 is fixed on a control shaft 40 for transmitting a driving force to the range switching valve 30. The rotation of the DC motor 34 is transmitted to the control shaft 40 at a reduced speed due to the engagement between the worm 38 of the drive shaft 36 and the worm wheel 42. And control axis 40
Rotates the spool of the range switching valve 30 in the axial direction thereof via the lever 44 fixed on the shaft. Therefore, the DC motor 34 functions as a kind of actuator that drives the range switching valve 30 for the switching.

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

In FIG. 1A, a range control unit 20 (SBW control unit), which is a first control unit, uses a microcomputer, and stores programs necessary for various software processes for switching the traveling range of the automatic transmission. A read-only memory (ROM) stored therein, a central processing unit (CPU) for executing this program, and a writable memory (RA) for temporarily storing variables necessary for the program.
M) and the like.

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

The range control section 20 receives a range signal a output by operating the range selection switch 10 and receives the range signal a in response to the range signal a.
An electric signal is output to the DC motor 34 to drive the DC motor 0. Further, the range signal a is also output to the automatic transmission control unit 22 and the engine control unit 24 at the same time.

On the side of the automatic transmission, there is provided a position sensor 50 as a range position detector for the range switching valve 30. 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. The signals are output to the control unit 22 and the engine control unit 24, respectively.

The range control unit 20, the automatic transmission control unit 2
2 and in each of the engine control units 24, whether or not the range signal a and the detection signal b match, that is, the select range intended by the driver matches the actual travel range in the automatic transmission. Is determined.
In addition, the range control unit 20 controls the automatic transmission control unit 22 and the engine control unit 2 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 clearly wrong.
4 to output a cancel signal c. The obvious erroneous operation of the range selection switch 10 is, for example, a case where the switch of the reverse range is turned on while the vehicle is traveling forward.

In the range control unit 20 and the automatic transmission control unit 22, when the range signal a and the detection signal b do not match and the cancel signal c is not on, both control units 20, 22 are used. 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 transmission 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 matches the travel range M of the automatic transmission based on the detection signal b. Proceed to step 2 and end the process if they match. In step 2, it is determined whether or not the cancel signal c output from the range control unit 20 is on. If the cancel signal c is on, the process ends.

In step 2, the cancel signal c
If it is determined that is not turned on, the routine proceeds to the next step 3, where it is determined whether or not a predetermined time has elapsed. If the predetermined 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 why the elapse of the predetermined time is determined in step 4 is that an instantaneous abnormality due to noise or the like immediately returns to a normal state.

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.
Even if an abnormality occurs in the processing of
The engine is stopped by the process of No. 4. In this embodiment, as the second control unit, the automatic transmission control unit 22 is used.
Since it is also used, its reliability is further enhanced.

Second Embodiment FIG. 3 shows an electrical system diagram of automatic transmission control in a second embodiment. In this drawing, a range display device 60 is incorporated in an instrument panel or the like located in front of a driver's seat. And, as already described, the range control unit 20
Outputs an electric signal to the DC motor 34 in accordance with the range signal a from the range selection switch 10 and outputs a signal based on the range signal a to the range display device 60. This causes the range display device 60 to light 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, a range switching valve is generated by a failure of the DC motor 34 due to a motor lock, an electric short circuit or a disconnection. 30 may not be controllable. In this case, the range controller 20 determines that a motor failure has occurred, and outputs a failure signal to the range display device 60 to blink the current traveling range of the automatic transmission.

However, even at the time of motor failure, when the range signal a and the detection signal b from the position sensor 50 match, that is, when the select range by the driver and the travel range of the automatic transmission match. In this case, it is not necessary to display the running range on the range display device 60 in a blinking manner.

According to the present embodiment, if the range intended by the driver is different from the current traveling range of the automatic transmission when the DC motor 34 fails, the traveling range is displayed on the range display device 60 in a blinking manner. Let the driver know. 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 this and stops the engine. Safety measures are also taken in consideration of the inability to control the automatic transmission due to an abnormality.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating 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 a traveling range of the automatic transmission and a driving mechanism thereof.

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

[Explanation of symbols]

 Reference Signs List 10 range selection switch 20 first control unit (range control unit) 24 second control unit (for example, engine control unit) 30 range switching valve 34 actuator (DC motor) 50 range position detector (position sensor)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // F16H 59:12 59:68 (56) References JP-A-1-131466 (JP, A) JP-A-2-136547 ( JP, A) JP-A-2-308951 (JP, A) JP-A-63-183254 (JP, A) JP-A-3-264751 (JP, A) JP-A-2-227774 (JP, A) Sho 61-94432 (JP, U) Actual opening Sho 61-1337859 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60K 41/00-41/28 F02D 17/04 F02D 29 / 00-29/06 F02D 43/00-45/00

Claims (1)

(57) [Claims] 1. An actuator for driving a range switching valve of an automatic transmission, a range selection switch operated by a driver, a range position detector for detecting a range position of the range switching valve, and an output from the range selection switch. A first control unit that outputs an electric signal corresponding to the range signal to the actuator to the actuator, and a control device for an automatic transmission including a second control unit that is different from the control unit; The one control unit and the second control unit individually receive the range signal and the detection signal from the range position detector, and determine whether these two signals match, The second control unit receives a cancel signal output from the first control unit while the range switching valve is being driven or when the driver detects an erroneous operation of the range selection switch. And the detection signal is inconsistent, and when there is no input of the cancel signal, it is determined that the processing of the first control unit is abnormal and outputs a signal for stopping the engine. Control device for automatic transmission.