Method For Detecting Brake Circuit Failure
3 Assignments
0 Petitions
Accused Products
Abstract
A method is provided for detecting a fault condition in a hydraulic brake system of a vehicle having a first hydraulic brake circuit and a second hydraulic brake circuit. A correlation ratio is determined between a measured pressure and the actual vehicle acceleration. A first wheel velocity differential is determined and a second wheel velocity differential is determined. A weighting value is selected in response to determining whether the correlation ratio is within the predetermined range and whether the first wheel velocity differential and the second wheel velocity differential are opposite signs. The selected weighting value is added to a fault counter. A determination is made whether the fault counter is equal to or greater than a predetermined threshold. A fault condition is detected in response to the fault counter greater than or equal to the first predetermined threshold.
40 Citations
76 Claims
-
1-56. -56. (canceled)
-
57. A method for detecting a fault condition in a dual circuit hydraulic vehicle brake system operative to provide both antilock and vehicle stability braking functions, the brake system including a first hydraulic brake circuit for actuating brakes for a first set of wheels and a second hydraulic brake circuit hydraulically isolated from the first circuit for actuating brakes for a second set of wheels, the brake system also including only a single pressure sensor, the single pressure sensor coupled to the first circuit and being operative to measure brake pressure as commanded by a vehicle driver during a braking operation of the vehicle, the brake system further including sensors other than the single pressure sensor for measuring vehicle operating characteristics which occur during the braking operation and which can be used to determine the actual deceleration of the vehicle, the method comprising the steps of:
-
during a braking operation of the vehicle, determining an expected vehicle deceleration value based upon the measured pressure in the first brake circuit; determining an actual vehicle deceleration value of the vehicle based on information obtained by one or more of the other sensors; and detecting a fault condition in the event the correlation between the expected deceleration value and the actual deceleration value does not meet predetermined criteria. - View Dependent Claims (58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
-
-
69. A method for detecting a fault condition in a dual circuit hydraulic vehicle brake system operative to provide both antilock and vehicle stability braking functions, the brake system including a first hydraulic brake circuit for actuating brakes for a first set of wheels, and a second hydraulic brake circuit hydraulically isolated from the first circuit for actuating brakes for a second set of wheels, the brake system also including a wheel speed sensor coupled to measure the velocity of each of the wheels, the method comprising the steps of:
-
determining a first wheel velocity difference between a first wheel of the first set of wheels and a first wheel of the second set of wheels; determining a second wheel velocity difference between a second wheel of the first set of wheels and a second wheel of the second set of wheels; and detecting a fault condition in the event the correlation between the first wheel velocity difference and the second wheel velocity difference does not meet predetermined criteria. - View Dependent Claims (70, 71)
-
-
72. A hydraulic brake circuit fault detection system comprising:
-
a braking control system including an vehicle brake module that is operable in at least one operating state; a pressure sensor for monitoring a hydraulic brake circuit; and a controller for receiving a plurality of vehicle operating inputs, said controller determining a first wheel speed differential of a first set of wheels and a second wheel speed differential of a second set of wheels and an expected acceleration in response to said received inputs; wherein said controller compares said expected acceleration with an actual vehicle acceleration and determines a ratio flag condition in response to, wherein said controller compares said first wheel velocity differential and said second wheel velocity differential and determines a slip flag condition in response to, and wherein said controller detects a fault condition in response to said ratio flag condition and said slip flag condition. - View Dependent Claims (73, 74, 75, 76)
-
Specification