Patent ID: 7654801

Claim:
A diaphragm pump: comprising: a pump body; a hydraulic control chamber, in said pump body, disposed between a piston and a diaphragm; means for compensating leaks from the hydraulic control chamber, said means comprising a refilling duct opening out into the hydraulic control chamber via a compensation shutter configured to be driven between a closed first position and an open second position by the diaphragm, the diaphragm being subjected to a force of a suction assistance spring, wherein the compensation shutter has a control rod with a free end facing the diaphragm, the compensation shutter configured to be driven to the open second position by the diaphragm pressing against said free end of said control rod during a suction overtravel, said suction-assistance spring being between said compensation shutter and a shoulder carried by the end of a second rod secured to the diaphragm and extending along an axis of the shutter to return the diaphragm toward said free end of the control rod, said suction-assistance spring being biased to return the compensation shutter to the closed first position, and wherein said suction-assistance spring and said compensation shutter form a moving assembly that is movable as a non-compressible assembly by the diaphragm during suction overtravel.