Rotary piston pump, has elastic bellows forming seal around crankshaft to prevent contamination with lubricant

摘要

An elastic bellows (24) is located in the curved crankshaft region (10) between the crankshaft (8, 8) and crank journals, forming a seal around the crankshaft. The edges of the bellows are secured tightly to the piston (12) and pump casing (2). The pump (1) has parallel rotating pistons mounted on the crank journals of a crankshaft inside an enclosed space in the pump casing. A chamber surface (16) which has adjoining regions with convex and concave profiles with respect to a plane extending perpendicular to the crankshaft axis is provided in the piston periphery and is in sliding contact with a corresponding chamber surface (17) in the casing. The space between the two chamber surfaces is sealed by side surfaces (4) of the casing. A suction hole (21) is provided in the casing outside the chamber surfaces and an exit channel (22) with a check valve (23) in provided in the chamber surface engagement region of the casing.