Monitor system for hydraulic pressure circuits of vehicles

• US 5,935,186 A
• Filed: 11/15/1996
• Issued: 08/10/1999
• Est. Priority Date: 11/17/1995
• Status: Expired due to Term

• Current Assignee: Advics Company Limited (Aisin Corp.)
• Original Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Inventors: Yamazaki, Norio, Yasui, Yoshiyuki, Itoh, Takayuki, Fukami, Masanobu, Tozu, Kenji
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/749,224
• Time in Patent Office: 998 Days
• Field of Search: 701/36, 701/41, 701/69, 701/70, 701/71, 701/72, 701/75, 701/78, 701/79, 701/76, 701/83, 701/82, 303/9.62, 303/113.5, 303/116.1, 303/119.1, 303/116.2, 303/146, 303/115.2, 303/163, 303/165, 303/158, 303/173, 303/122.07
• US Class Current: 701/78
• CPC Class Codes: B60T 17/221 Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems hydraulic pressure systems in general F15B19/00, F15B21/04; testing structures or apparatus G01M
• CPC Class Codes: B60T 2270/206 Monitoring, e.g. parameter monitoring, plausibility check
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60T 8/1764 Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear

Abstract

The present invention is directed to a monitor system for use in an automotive vehicle which includes wheel brake cylinders operatively mounted on wheels, respectively, and which includes a hydraulic pressure control apparatus for generating a hydraulic braking pressure in response to depression of a brake pedal. A difference calculating unit calculates a difference between a wheel speed of a wheel to be determined and a wheel speed of at least one reference wheel which is compared with a predetermined value, when a braking operation detection unit detects a braking operation. Then, a determination unit compares the difference with a predetermined value, and determines that the pressure circuit provided for the wheel to be determined is normal, when the difference is lower than the predetermined value. An output unit may be provided to produce an output signal when a period of time during which the difference continues to be equal to or greater than the predetermined value, exceeds a predetermined time.

Claims

1. A monitor system for monitoring hydraulic pressure circuits disposed in an automotive vehicle having a hydraulic pressure control apparatus for generating a hydraulic braking pressure in response to depression of a brake pedal, and wheel brake cylinders operatively mounted on wheels of said vehicle for braking said wheels and connected to said hydraulic pressure control apparatus through said hydraulic pressure circuits, respectively, comprising:

wheel speed detection means for detecting wheel speeds of said wheels, respectively;

braking operation detection means for detecting a braking operation in response to depression of said brake pedal;

difference calculating means for calculating a difference between a wheel speed of a wheel to be determined and a wheel speed of at least one reference wheel to be compared with the wheel speed of said wheel to be determined, when said braking operation detection means detects the braking operation, said reference wheel having a certain relationship with said wheel to be determined; and

determination means for comparing the difference calculated by said difference calculating means with a predetermined value, and determining that one of said pressure circuits provided for said wheel to be determined is normal, when the difference calculated by said difference calculating means is lower than the predetermined value.

2. The monitor system as claimed in claim 1, wherein said difference calculating means calculates the differences between the wheel speed of said wheel to be determined and the wheel speeds of the rest of said wheels, when said braking operation detection means detects the braking operation, and wherein said determination means compares the differences calculated by said difference calculating means with the predetermined value, respectively, and determines that one of said pressure circuits provided for said wheel to be determined is normal, when all of the differences are lower than the predetermined value.

3. The monitor system as claimed in claim 1, further comprising:

output means for producing an output signal when a period of time during which the difference between the wheel speed of said wheel to be determined and the wheel speed of said reference wheel continues to be equal to or greater than the predetermined value, exceeds a predetermined time.

4. The monitor system as claimed in claim 1, wherein said hydraulic pressure control apparatus includes a master cylinder for generating the hydraulic braking pressure in response to depression of said brake pedal, and modulators disposed in said hydraulic pressure circuits, respectively, for controlling the hydraulic braking pressure therein in accordance with the condition of each wheel of said vehicle.

5. A monitor system for monitoring hydraulic pressure circuits disposed in an automotive vehicle having a hydraulic pressure control apparatus for generating a hydraulic braking pressure in response to depression of a brake pedal, and wheel brake cylinders operatively mounted on wheels of said vehicle for braking said wheels and connected to said hydraulic pressure control apparatus through said hydraulic pressure circuits, respectively, comprising:

wheel speed detection means for detecting wheel speeds of said wheels, respectively;

vehicle speed estimation means for calculating an estimated vehicle speed for each wheel on the basis of the wheel speeds detected by said wheel speed detection means;

braking operation detection means for detecting a braking operation in response to depression of said brake pedal;

slip rate calculation means for calculating a wheel slip rate for a wheel to be determined, on the basis of a wheel speed of said wheel to be determined out of the wheel speeds detected by said wheel speed detection means and the estimated vehicle speed calculated by said vehicle speed estimation means, when said braking operation detection means detects the braking operation; and

determination means for comparing the wheel slip rate calculated by said slip rate calculation means for said wheel to be determined, with a predetermined slip rate, and determining that one of said pressure circuits provided for said wheel to be determined is normal, when the wheel slip rate calculated by said slip rate calculation means for said wheel to be determined exceeds the predetermined slip rate.

6. The monitor system as claimed in claim 5, further comprising:

normalizing means for normalizing said estimated vehicle speed for each wheel calculated by said vehicle speed estimation means in accordance with a condition of each wheel to provide a normalized vehicle speed,

wherein said slip rate calculation means calculates the wheel slip rate for a wheel to be determined on the basis of the wheel speed of said wheel to be determined and the normalized vehicle speed, when said braking operation detection means detects the braking operation.

7. The monitor system as claimed in claim 6, further comprising:

output means for producing an output signal when a period of time during which the wheel slip rate for said wheel to be determined continues to be equal to or lower than the predetermined slip rate, exceeds a predetermined time.

8. The monitor system as claimed in claim 5, wherein said hydraulic pressure control apparatus includes a master cylinder for generating the hydraulic braking pressure in response to depression of said brake pedal, and modulators disposed in said hydraulic pressure circuits, respectively, for controlling the hydraulic braking pressure therein in accordance with the condition of each wheel of said vehicle.