Patent ID: 7198074

Claim:
A combination vacuum and pressure pump comprising: a pump housing having an opening for connection to a container to be evacuated or pressurized; a pump chamber within the pump housing; a piston in sliding, substantially airtight engagement with walls of the pump chamber, adapted to reciprocate between pressure and vacuum strokes within the chamber; a rotary drive in the pump housing powering a rotatable output shaft; a piston drive operatively connecting the motor output shaft and the piston adapted to convert rotational movement of the output shaft to reciprocating motion of the piston within the pump chamber; at least one one-way valve, communicating with the pump chamber, permitting passage of fluid only into or out of the pump chamber; a selectable flow control member in the pump housing having a pair of passages therein and movable between pressure and vacuum positions; in the pressure position one of the selectable flow control member passages connecting the pump chamber and the pump housing opening to permit passage of fluid from the pump chamber out of the housing connection opening during the piston pressure stroke, and the other of the selectable flow control member passages permitting passage of fluid into the pump chamber from a region external to the pump chamber through a one-way valve during the piston vacuum stroke; and in the vacuum position one of the first selectable flow control member passages connecting a one-way valve to the pump chamber to permit passage of fluid from the pump chamber out to the external region through the one-way valve during the piston pressure stroke, and the other of the selectable flow control member passages permitting passage of fluid from the housing connection opening to the pump chamber during the piston vacuum stroke.