Multiplexing antilock brake apply channels

• US 5,234,261 A
• Filed: 12/07/1992
• Issued: 08/10/1993
• Est. Priority Date: 07/01/1991
• Status: Expired due to Term

• Current Assignee: Delco Electronics Corporation (Motors Liquidation Co. GUC Trust), General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: Delco Electronics Corporation (Motors Liquidation Co. GUC Trust), General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Leyes, Annabelle E., Horner, Fred J., Parker, Donald L., Kumke, Dale J., Schenk, Donald E.
• Primary Examiner(s): Oberleitner, Robert J.
• Assistant Examiner(s): Young, Lee W.
• Application Number:
  US07/987,102
• Time in Patent Office: 246 Days
• Field of Search: 303/100, 303/102, 303/103, 303/111, 303/113.1, 303/113.4, 303/115.1, 303/116.1, 303/DIG. 3, 303/DIG. 4, 364/426.02
• US Class Current: 303/158
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60T 8/347 3 Channel systems B60T8/345 takes precedence
• CPC Class Codes: B60T 8/36 including a pilot valve responding to an electromagnetic force
• CPC Class Codes: B60T 8/445 replenishing the released brake fluid volume into the brake piping

Abstract

An ABS system has a plurality of brake channels receiving apply pressure directly from a pump without an accumulator during ABS operation. To assure sufficient pressure for all channels during ABS reapply modes the channels are multiplexed to apply one at a time and keeping on hold other channels scheduled for apply. Several states of brake application are identified and the states are prioritized for each channel so that the multiplexing is ordered according to channel priority.

Claims

1. In a wheel lock control system for a brake system of a vehicle having a wheel lock control hydraulic pressure source, a hydraulic pressure reservoir, and several wheel brake channels, a method of controlling hydraulic brake pressure in the wheel brake channels for wheel lock controlled braking, the method comprising the steps of:

for each wheel brake channel, sensing a requirement for wheel lock controlled braking;

for each wheel brake channel for which the requirement for wheel lock controlled braking is sensed, repeatedly determining one of a pressure release, hold and apply mode;

when the pressure apply mode is concurrently determined for multiple wheel brake channels, sequentially selecting said multiple wheel brake channels one at a time and resetting the determined pressure apply mode of the other ones of said multiple wheel brake channels to the pressure hold mode to thereby limit the determined apply mode to a single brake channel at any given time; and

concurrently;

(A) releasing hydraulic brake pressure to the hydraulic pressure reservoir from each of the wheel brake channels for which the pressure release mode is determined,

(B) holding hydraulic brake pressure in each of the wheel brake channels for which the pressure hold mode is determined, and

(C) supplying hydraulic brake pressure form the wheel lock control hydraulic pressure source to the wheel brake channel for which the pressure apply mode is determined.

2. In a wheel lock control system for a brake system of a vehicle having a wheel lock control hydraulic pressure source, a hydraulic pressure reservoir, and several wheel brake channels, a method of controlling hydraulic brake pressure int he wheel brake channels for wheel lock controlled braking, the method comprising the steps of:

for each wheel brake channel, sensing a requirement for wheel lock controlled braking;

for each wheel brake channel for which the requirement for wheel lock controlled baking is sensed, repeatedly determining one of a pressure release, hold and apply mode;

selecting one of the wheel brake channels for which the pressure apply mode is determined, all remaining ones of the wheel brake channels for which the pressure apply mode is determined comprising non-selected wheel brake channels;

simultaneously (A) releasing hydraulic brake pressure to the hydraulic pressure reservoir from each of the wheel brake channels of which the pressure release mode is determined, (B) holding hydraulic brake pressure in each of the wheel brake channels for which the pressure hold mode is determined, and (C) supplying hydraulic brake pressure form the wheel lock control hydraulic pressure source to the selected one of the wheel brake channels for which the pressure apply mode is determined;

holding hydraulic brake pressure in the non-selected wheel brake channels; and

when the pressure apply mode is determined for multiple wheel brake channels, repeatedly changing the selected one of the wheel brake channels for which the pressure apply mode is determined to repeatedly change the wheel brake channel having a determined apply mode to which hydraulic brake pressure is supplied form the wheel lock control hydraulic pressure source.

3. In a wheel lock control system for a brake system of a vehicle having a wheel lock control hydraulic pressure source, a hydraulic pressure reservoir, and several wheel brake channels, a method of controlling hydraulic brake pressure in the wheel brake channels for wheel lock controlled braking, the method comprising the steps of:

for each wheel brake channel, sensing a requirement for wheel lock controlled braking;

for each wheel brake channel for which the requirement for wheel lock controlled braking is sensed repeatedly determining one of a pressure release, hold and apply mode;

assigning a unique apply priority to each one of the wheel brake channels having a determined pressure apply mode form a predetermined schedule of priorities varying progressively form a low priority to a high priority;

selecting the wheel brake channel having the highest one of the assigned priorities, all remaining ones of ht wheel brake channels for which the pressure apply mode is determined comprising non-selected wheel brake channels;

simultaneously (A) releasing hydraulic brake pressure to the hydraulic pressure reservoir from each of the wheel brake channels for which the pressure release mode is determined, (B) holding hydraulic brake pressure in each of the wheel brake channels for which the pressure hold mode is determined, and (C) supplying hydraulic brake pressure from the wheel lock control hydraulic pressure source to the selected wheel brake channel having the highest one of the assigned priorities; and

holding hydraulic brake pressure in the non-selected wheel brake channels.