Special control mode for one-solenoid valves

In a process of operating a vehicle braking system where vehicle motion and wheel motion are monitored to determine when to invoke an antilock braking mode in a brake system wherein an operational fluid having a first high pressure is presented to effect a brake application, said operational fluid having a first steep pressure gradient that transitions into a first gradual pressure gradient as fluid pressure build up starts from a first lower pressure and approaches a second pressure level of a source of fluid, said antilock braking mode being invoked when a predetermined difference occurs between said vehicle motion and said wheel motion such that said first high pressure is released from said brake system to attenuate such difference, said operational fluid having a second steep pressure gradient when first high fluid pressure is initially released from the system and approaches a lower second pressure fluid level wherein said vehicle motion and said wheel motion are essentially equal, process including the steps of:

• enabling a single-solenoid valve to release said operational fluid from said brake system and reduce said first high fluid pressure to said lower second fluid pressure to effect said antilock braking mode;
• monitoring the fluid pressure release time T1 for the first high fluid pressure to go to said second lower fluid pressure level;
• alternately enabling and disabling duty cycles for said single solenoid valve to maintain said lower second fluid pressure at a substantially constant reduced pressure until wheel motion is greater that said vehicle motion, said duty cycles having an energized time te and a de-energized time td wherein a ratio of energized time te to de-energized time td is a function of said first high fluid pressure of the operational fluid and the release time T1 for the operational fluid to go from said first high fluid pressure and said lower second fluid pressure, said duty cycles having an initial cycle wherein said low second fluid pressure is approximately one half of said high first fluid pressure to define an initial release time T1 such that when a lower fluid pressure than said lower second fluid pressure is required to achieve continuity between said vehicle and wheel motion a longer release time T1 occurs and as a result said duty cycles thereafter are initiated with a shorter de-energized time td and a longer energized time te and when a higher fluid pressure than said lower second fluid pressure is required to achieve continuity between said vehicle and wheel motion a shorter release time T1 occurs and as a result said duty cycles thereafter are initiated with a longer de-energized time td and a shorter energized time te;
• and
• subsequently enabling said single solenoid valve to rebuild operational fluid pressure by changing the ratio of the energized time te during which the valve to the de-energized time td during which said single solenoid valve is disabled to rebuild fluid pressure in said operational fluid to a second operational fluid level until a sensed condition indicated a second difference occurs between said wheel and vehicle motion.