Pendular piston pump having a cup-shaped sealing element

A pendular pump comprising a housing member having an internal surface bounding internal space including an elongated cylinder bore;

• a pendular piston member movably received in said cylinder bore and delimiting a pumping chamber therein, said housing member having fluid inlet and fluid outlet means communicating with said pumping chamber during different stages of pendular movement of said piston member and said piston member including a piston and a connecting member rigid with said piston;
• means for moving said piston member in said cylinder bore so that said piston member performs a pendular movement axially of said cylinder bore, said moving means including a crank drive articulately connected to said connecting member so that said piston member performs said pendular movement during the operation of said crank drive;
• and sealing means interposed between said piston member and said internal surface and including at least one resilient sealing element having a substantially radially extending supporting section at least partially mounted on said piston member, at least one lip section having a substantially constant thickness and being urged into uninterrupted sealing contact with said internal surface during each stage of pendular movement of the piston member solely by the resiliency of the material of said sealing element, and a third section between and integral with said supporting and lip sections, said third section mounting said lip section on said supporting section for ready tiliting relative thereto and having a groove therein which extends circumferentially of said sealing element between said supporting section and said lip section to facilitate tilting of said lip section relative to said supporting section in accordance with the geometry of pendular movement of said piston member, said supporting section projecting radially outwardly beyond said piston member and having a thickness exceeding that of said lip section to guide said piston member in said bore and to maintain the piston member out of contact with said internal regardless of the extent of wear upon said lip section.