Patent ID: 6217128
Filing Date: 2001-04-17
Classification: B60T,B62D

Abstract:
A valve arrangement for use with a steering assist system having left and right brake actuating members, the valve arrangement comprising:a valve body defining a left brake port adapted for connection to a left hydraulic brake and a right brake port adapted for connection to a right hydraulic brake, the valve body also defining left and right brake pressure ports adapted for connection to a source of hydraulic brake pressure;the valve body also defining a left brake passageway for providing fluid communication between the left brake pressure port and the left brake port, and a right brake passageway for providing fluid communication between the right brake pressure port and the right brake port;a left brake push rod for controlling hydraulic fluid flow through the left brake port and through the left brake pressure port, the left brake push rod being adapted to be operatively coupled to the left brake actuating member such that the left brake actuating member can apply an axial actuating force to the left brake push rod;a right brake push rod for controlling hydraulic fluid flow through the right brake port and through the right brake pressure port, the right brake push rod being adapted to be operatively coupled to the right brake actuating member such that the right brake actuating member can apply an axial actuating force to the right brake push rod;a left brake hydraulic pilot volume in fluid communication with the left brake passageway, the left brake hydraulic pilot volume being positioned such that hydraulic fluid within the left brake hydraulic pilot volume applies hydraulic pressure axially against the left brake push rod, the hydraulic pressure opposing the axial actuating force provided by the left brake push rod;a right brake hydraulic pilot volume in fluid communication with the right brake passageway, the right brake hydraulic pilot volume being positioned such that hydraulic fluid within the right brake hydraulic pilot volume applies hydraulic pressure axially against the right brake push rod, the hydraulic pressure opposing the axial actuating force provided by the right brake push rod;a bypass passage arrangement for providing fluid communication between the left brake passageway and the right brake port, and for providing fluid communication between the right brake passageway and the left brake port; anda plurality of valves for: i) closing the left brake passageway and directing hydraulic fluid pressure from the right brake passageway through the bypass passage arrangement to the left brake port when the hydraulic pressure in the right hydraulic pilot volume exceeds the hydraulic pressure in the left hydraulic pilot volume; and ii) closing the right brake passageway and directing hydraulic fluid pressure from the left brake passageway through the bypass passage arrangement to the right brake port when the pressure in the left hydraulic pilot volume exceeds the hydraulic pressure in the right hydraulic pilot volume.