Patent ID: 8231842

Claim:
A positive displacement pump ( 1 ) comprising: a pump cylinder ( 2 ) with a longitudinal axis ( 3 ), a cylinder wall ( 4 ) extending parallel to the longitudinal axis ( 3 ), a cylinder bottom ( 5 ) extending essentially perpendicular to the longitudinal axis ( 3 ), and a cylinder outlet ( 6 ) that is located in or close to the cylinder bottom ( 5 ); a pump piston ( 7 ) with a piston front ( 8 ) that is reciprocally movable inside the pump cylinder ( 2 ) in direction of the longitudinal axis ( 3 ); a cylinder space ( 9 ) that is located inside the pump cylinder ( 2 ) and that is defined by the cylinder wall ( 4 ), the cylinder bottom ( 5 ), and the piston front ( 8 ); a pressure sensor ( 10 ) for detecting the pressure in the cylinder space ( 9 ), the pressure sensor being located in or outside a rear opening ( 26 ) which is located at an end ( 34 ) of the pump cylinder ( 2 ) that is opposite to the cylinder bottom ( 5 ); and a pressure channel ( 12 ) for providing fluidic connection between the cylinder space ( 9 ) and the pressure sensor ( 10 ), wherein the cylinder wall ( 4 ) comprises a piston sleeve ( 14 ), the piston sleeve ( 14 ) being located on the inner side of the cylinder wall ( 4 ) and extending over essentially the entire length of the cylinder wall ( 4 ) to the cylinder bottom ( 5 ), and wherein the pressure channel ( 12 ) comprises a main portion ( 13 ), which is accomplished as at least one slot ( 15 ) in the piston sleeve ( 14 ), said main portion ( 13 ) extending parallel to the longitudinal axis ( 3 ) of the pump cylinder ( 2 ) from the cylinder bottom ( 5 ) to or beyond the rear opening ( 26 ) at an end ( 34 ) of the pump cylinder ( 2 ) over substantially the entire length of the piston sleeve ( 14 ).