Pump and valve means

Claim 1

A pump and valve means comprising: a. a housing defining a pump chamber, a cylindrical valve chamber, spaced fluid ports providing inlet and outlet means to said valve chamber, and passage means including fluid passages extending from spaced portions of said valve chamber to spaced portions of said pump chamber; b. pump means in said pump chamber operative to pump fluids selectively through said passage means toward said spaced portions of the valve chamber; c. a pair of primary check valves each disposed between a different one of said spaced ports and a different one of said spaced portions of the valve chamber and each including a check valve member and an annular seat defining one end of a check valve opening of predetermined diameter to a respective end of said valve chamber, each of said check valve members being yieldingly urged toward engagement with its respective valve seat; d. a valve element mounted in said valve chamber for movement alternately in opposite directions toward said check valve members and having opposite portions each engageable with a different one of said check valve members to move the same out of seating engagement with its respective valve seat; e. said valve element having opposite surface portions each having a total surface area substantially greater than the area of an adjacent one of said openings and exposed to pressure of fluid in said passage means to move into check valve opening engagement with one of said check valve members responsive to predetermined fluid pressure against said surface area adjacent the other of said check valve members; f. said valve element including a longitudinally central portion defining a fluid passage portion communicating with a fluid reservoir; g. said passage means including relatively large diameter branch passages selectively communicating with said passage portions and a respective one of said fluid passages responsive to predetermined movement of said valve element in opposite directions from a neutral position intermediate the opposite ends of said valve chambers; h. and a pair of secondary check valves one each disposed in a different one of said branch passages, said secondary check valves being arranged to prevent return flow of fluid to said fluid passage portion through their respective branch passages; i. said passage means further including a pair of relatively small diameter shunt passages each connecting a different one of said fluid passages with a respective one of said branch passages between its respective secondary check valve and said valve chamber and passage portion.