Failure detecting system and method for automatic transmission

• US 5,573,475 A
• Filed: 06/16/1995
• Issued: 11/12/1996
• Est. Priority Date: 07/29/1993
• Status: Expired due to Fees

• Current Assignee: Fuji Jukogyo KK (Subaru Corp.)
• Original Assignee: Fuji Jukogyo KK (Subaru Corp.)
• Inventors: Tezuka, Kazunari, Sakakiyama, Ryuzo, Shirakawa, Kiminaga
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): JENSEN, NATHAN
• Application Number:
  US08/491,593
• Time in Patent Office: 515 Days
• Field of Search: 192/4 A, 477/94, 477/95, 477/96, 477/906
• US Class Current: 477/94
• CPC Class Codes: B60K 31/00 Vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed, i.e. preventing speed from exceeding an arbitrarily established velocity or maintaining speed at a particular velocity, as selected by the vehicle operator fittings acting on two or more sub-units B60W30/14; speedometers G01P; systems or devices for controlling speed in general G05D13/00 ; in traffic anti-collision system for road vehicles G08G1/16
• CPC Class Codes: B60K 31/04 and means for comparing one electrical quantity, e.g. voltage, pulse, waveform, flux, or the like, with another quantity of a like kind, which comparison means is involved in the development of an electrical signal which is fed into the controlling means
• CPC Class Codes: B60K 31/047 the memory being digital
• CPC Class Codes: B60T 17/22 Devices for monitoring or checking brake systems; Signal devices
• CPC Class Codes: B60W 2050/021 Means for detecting failure or malfunction
• CPC Class Codes: B60W 2050/0215 Sensor drifts or sensor failures
• CPC Class Codes: B60W 2510/0623 Fuel flow rate
• CPC Class Codes: B60W 2510/0628 Inlet air flow rate
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2540/16 Ratio selector position
• CPC Class Codes: F16H 2061/1208 with diagnostic check cycles; Monitoring of failures
• CPC Class Codes: F16H 2061/1224 Adapting to failures or work around with other constraints, e.g. circumvention by avoiding use of failed parts
• CPC Class Codes: F16H 2061/1244 Keeping the current state
• CPC Class Codes: F16H 2061/1248 Resuming normal operation
• CPC Class Codes: F16H 2061/1284 the failing part is a sensor
• CPC Class Codes: F16H 2312/022 Preparing to drive off
• CPC Class Codes: F16H 59/08 Range selector apparatus
• CPC Class Codes: F16H 59/105 consisting of electrical switches or sensors
• CPC Class Codes: F16H 59/22 : Idle position
• CPC Class Codes: F16H 59/24 : dependent on the throttle opening
• CPC Class Codes: F16H 59/42 : Input shaft speed
• CPC Class Codes: F16H 59/44 : dependent on machine speed of the machine, e.g. the vehicle
• CPC Class Codes: F16H 59/54 : dependent on signals from the brakes, e.g. parking brakes
• CPC Class Codes: F16H 59/72 : dependent on oil characteristics, e.g. temperature, viscosity
• CPC Class Codes: F16H 59/74 : Inputs being a function of engine parameters F16H59/14 takes precedence
• CPC Class Codes: F16H 61/0213 : characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/12 : Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures
• CPC Class Codes: F16H 61/16 : Inhibiting or initiating shift during unfavourable conditions, e.g. preventing forward reverse shift at high vehicle speed, preventing engine over speed unintentional control input F16H61/18
• CPC Class Codes: F16H 63/40 : comprising signals other than signals for actuating the final output mechanisms
• CPC Class Codes: F16H 63/42 : Ratio indicator devices
• CPC Class Codes: Y10S 477/906 : Means detecting or ameliorating the effects of malfunction or potential malfunction
• CPC Class Codes: Y10T 74/1926 : Speed responsive

Abstract

In case where an engine rotational detection signal from an ignition pulse generator is not appropriately detected even if an amount of induction air and a fuel injection amount are larger than predetermined values, an engine rotational signal failure is decided, and an automatic transmission is controlled in a state before the decision. Therefore, the automatic transmission control based on the engine rotational speed such as, for example, a speed shift control (ordinarily a shift control), a lockup control (ordinarily a lockup control, a smooth control), a line pressure control (ordinarily a line pressure control, a starting time control) can be appropriately controlled. Thus, the automatic transmission control can be executed based on the engine rotational speed. In case where any of the conditions of (1) when the cruise control signal is erroneously turned on in case where a vehicle speed is smaller than a value in the case of non operation of a cruise control, (2) when the cruise control signal which ought to be released is erroneously turned on at the time of turning a brake switch on, (l) when the cruise control signal is erroneously turned on in an "N" or "P" range, (4) when any of the paragraphs (1) to (3) is continued for a predetermined time, are satisfied, a failure of the cruise control set signal line is detected, and the automatic transmission control of the cruise control is prohibited. The normal state is recovered when an off signal of the cruise control set is detected in the above-described conditions. Accordingly, since a failure of the cruise control set signal line is reliably detected, the automatic transmission control is appropriately executed by using the cruise control signal. Thus, the automatic transmission control can be executed based on a cruise control signal.

Claims

1. A failure detecting system for an automatic transmission of a vehicle having a vehicle speed sensor mounted on said vehicle for sensing a vehicle speed and for generating a vehicle speed signal indicative thereof, comprising:

a brake switch mounted on said vehicle for detecting whether a brake system is operated or not and for generating a brake signal indicative thereof; and

transmission control prohibiting means, responsive to said vehicle speed signal and said brake signal, for prohibiting control of said automatic transmission based on said brake signal when a first predetermined number of times is counted while said vehicle speed decreases from a predetermined speed to a zero speed without detecting operation of said brake system, thereby indicating a failure in said brake system.

2. The failure detecting system according to claim 1, wherein:

said transmission control prohibiting means also prohibits control of said automatic transmission based on said brake signal when a second predetermined number of times is counted while a deceleration rate of said vehicle speed exceeds a predetermined deceleration rate without detecting operation of said brake system.

3. The failure detecting system according to claim 1, wherein:

said transmission control prohibiting means also prohibits control of said automatic transmission based on said brake signal when a deceleration rate exceeds a predetermined deceleration rate without detecting operation of said brake system.

4. A failure detecting system according to claim 1, wherein:

said first predetermined number of times is at least two times.

5. A failure detecting system according to claim 1 wherein;

said failure of said brake system is detected by a system having only one brake switch, and

said automatic transmission is accurately controlled independent of said brake signal.

6. A failure detecting system for an automatic transmission of a vehicle having a brake switch mounted on said vehicle for detecting whether a brake system is operated or not and for generating a brake signal indicative thereof, comprising:

an inhibitor switch provided on said automatic transmission for detecting a gear position and for producing a gear range signal indicative thereof; and

transmission control prohibiting means, responsive to said brake signal and said gear range signal, for prohibiting control of said automatic transmission based on said brake signal when a first predetermined number of times is counted without detecting operation of said brake system while said gear range signal changes from a parking range to a reverse range, thereby indicating a failure in said brake system.

7. A failure detecting system according to claim 6, wherein;

said failure of said brake system is detected by a system having only one switch, and

said automatic transmission is accurately controlled independent of said brake failure.

8. A failure detecting system for an automatic transmission of a vehicle having a vehicle speed sensor mounted on said vehicle for sensing a vehicle speed and for generating a vehicle speed signal indicative thereof and a brake switch mounted on said vehicle for detecting whether a brake system is operated or not and for generating a brake signal indicative thereof, comprising:

transmission control prohibiting means, responsive to said vehicle speed signal and said brake signal, for prohibiting control of said automatic transmission based on said brake signal when a first predetermined number of times is counted without detecting said brake system as being operated while said vehicle speed decreases from a predetermined speed to a zero speed, thereby indicating a failure in said brake system.

9. A failure detecting method for an automatic transmission of a vehicle having a vehicle speed sensor mounted on said vehicle for sensing a vehicle speed indicative thereof, comprising:

detecting whether a brake system is operated or not; and

prohibiting control of said automatic transmission based on said brake signal when a first predetermined number of times is counted without detecting said brake system as being operated while said vehicle speed decreases from a predetermined speed to a zero speed, thereby indicating a failure in said brake system.

10. The failure detecting method according to claim 9, wherein:

said prohibiting step further includes prohibiting control of said automatic transmission based on said brake signal when a second predetermined number of times is counted without detecting said brake system as being operated while a deceleration rate of said vehicle speed exceeds a predetermined rate.

11. The failure detecting method according to claim 9, wherein:

said prohibiting step further includes prohibiting control of said automatic transmission when a deceleration rate exceeds a predetermined rate without detecting said brake system as being operated.

12. A failure detecting method according to claim 9, wherein:

said failure of said brake system is detected by a system having only one brake switch, and

said automatic transmission is accurately controlled independent of said brake signal.

13. A failure detecting method for an automatic transmission of a vehicle having a brake switch mounted on said vehicle for detecting whether a brake system is operated or not, comprising:

detecting a gear position; and

prohibiting control of said automatic transmission based on said brake signal when a predetermined number of times is counted without detecting said brake system as being operated while said gear range signal changes from a parking range to a reverse range, thereby indicating failure of said brake system.

14. A failure detecting method according to claim 13, wherein:

said failure of said brake system is detected by a system having only one brake switch, and

said automatic transmission is accurately controlled independent of said brake signal.