Patent ID: 7993111

Claim:
Apparatus for enhancing the low temperature start-up of a power steering pump that includes: a pump for pumping hydraulic steering fluid through a single passage outlet orifice restricting element to a steering assist valve; a fluid flow control device connected to the output of said pump; said flow control device having a first supply side defined for receiving fluid under pressure from said pump output prior to said outlet orifice, a second supply side defined for receiving fluid under pressure from said pump output after said outlet orifice and before said steering assist valve, a bypass port connected to a fluid line that is in communication with an input fluid supply of said pump; a spool element within said flow control device being adjustable between said first supply side and said second supply side to control the amount of diversion of a portion of said fluid from said pump output to said bypass port; a biasing element within said flow control device to provide a predetermined biasing to said spool element; and a second flow restriction element disposed in a fluid passage downstream from said outlet orifice restricting element for increasing flow resistance of fluid in said fluid passage at low temperatures, said second flow restriction element having a plurality of fluid passages with a total wetted surface sidewall area that exceeds the wetted sidewall area of said single passage of said outlet orifice restricting element.