Patent ID: 8162632

Claim:
A piston pump, comprising: a housing; a rotor assembly rotatably disposed in the housing, the rotor assembly comprising: a rotor; a pumping chamber disposed in the rotor; a piston slidably disposed within the pumping chamber and movable between a first position and a second position therein; the housing comprising: a first housing inlet and a second housing inlet selectively fluidly communicating with the pumping chamber; a first housing outlet and a second housing outlet selectively fluidly communicating with the pumping chamber; an inlet cam assembly fixedly disposed in the housing, the inlet cam assembly having first and second inlet cam lobes operative to move the piston to the first position; and an outlet cam assembly fixedly disposed in the housing, the outlet cam assembly having first and second outlet cam lobes operative to move the piston to the second position; the rotor being rotatable sequentially between first, second, third and fourth positions relative to the housing, wherein when the rotor is in the first position, the pumping chamber is in fluid communication with the first housing inlet and in fluid isolation from the second housing inlet and from the first and second housing outlets; and the first inlet cam lobe urges the piston toward the first position to draw fluid into the pumping chamber via the first housing inlet; wherein when the rotor is in the second position, the pumping chamber is in fluid communication with the first housing outlet and in fluid isolation from the first and second housing inlets and from the second housing outlet; and the first outlet cam lobe urges the piston to the second position to expel fluid out of the pumping chamber via the first housing outlet; wherein when the rotor is in the third position, the pumping chamber is in fluid communication with the second housing inlet and in fluid isolation from the first housing inlet and from the first and second housing outlets; and the second inlet cam lobe urges the piston toward the first position to draw fluid into the pumping chamber via the second housing inlet; and wherein when the rotor is in the fourth position, the pumping chamber is in fluid communication with the second housing outlet and in fluid isolation from the first housing outlet and the first and second housing inlets; and the second outlet cam lobe urges the piston to the second position to expel fluid out of the pumping chamber via the second housing outlet.