Patent ID: 6120266
Filing Date: 2000-09-19
Classification: F04B

Abstract:
A piston mechanism with a flow passage through the piston, said piston mechanism comprising:a cylinder having a closable cylinder passage at one extremity and opening into an interior of a crank chamber at another extremity;a piston, axially movable in said cylinder, said piston having a front side and a rear side, a closable piston flow passage and a groove in an outer circumference thereof;a piston ring mounted in said groove such that said piston ring forms a seal between said piston and said cylinder, said piston ring mounted with an axial clearance in said groove so that it is axially movable in the groove;a movement mechanism arranged to axially move said piston in said cylinder, said movement mechanism comprising a crank shaft mounted in said crank chamber and a piston rod hingedly connected at one end to said piston by a first bearing and hingedly connected at another end to said crank shaft by a second bearing;said piston flow passage extending over said groove and opening at said rear side of said piston onto said first bearing; andsaid piston ring upon axial movement in the groove as a valve being operable to open and close said piston flow passage in response to piston movement in the cylinder.