Patent ID: 8864475
Filing Date: 2014-10-21
Classification: F04B,F05C

Abstract:
1. A pump for pumping a liquid, the pump comprising: a pump cylinder defining a passageway including a pump chamber section and a piston wash section, the pump cylinder including at least one liquid inlet and at least one liquid outlet communicating with the pump chamber section proximate a first end of the pump cylinder and a wash inlet and a wash outlet communicating with the piston wash section proximate a second end of the pump cylinder, the pump cylinder further defining a counterbore at the second end of the passageway and first and second axial wash channels extending from the wash inlet and the wash outlet, respectively, along opposite sides of the piston wash section to the counterbore; a displacement piston slidably received in the passageway at the second end of the pump cylinder, the displacement piston being slidable between the liquid inlet and outlet and the wash inlet and outlet to draw liquid into and to push liquid out of the pump chamber section; and a lip seal located at the second end of the pump cylinder and sealing against the displacement piston, wherein the wash inlet, the wash outlet, the first and second axial wash channels, and the counterbore form a wash flow path through the piston wash section that extends to the lip seal and allows a wash liquid to wash in a first direction along a first length of the displacement piston, around a portion of the lip seal, and then in a second direction along a second length of the displacement piston on an opposite side of the piston, wherein the second direction is opposite the first direction.