Patent ID: 7694622
Filing Date: 2010-04-13
Classification: F01L,F04B

Abstract:
1. A fluid pressure operated piston engine apparatus, comprising: a fluid pressure operated piston unit including a piston chamber, a piston mounted for reciprocation within said piston chamber, and a shaft coupled with said piston such that said piston and said shaft reciprocate together along a stroke having first and second ends; a valve configured to selectively direct pressurized fluid into said piston chamber on opposite first and second sides of said piston, said valve including a valve element movable between (i) a first position in which said valve directs the pressurized fluid into said piston chamber on the first side of said piston to move said shaft toward the first end of the stroke, and (ii) a second position in which said valve directs the pressurized fluid into said piston chamber on the second side of said piston to move said shaft toward the second end of the stroke; a valve shifting mechanism operatively coupling said shaft to said valve element, said valve shifting mechanism including a biasing device providing a first biasing force as said shaft approaches the first end of the stroke and a second biasing force as said shaft approaches the second end of the stroke; and a magnetic detent device including a valve actuating member coupled to said valve element and moveable between first and second magnetically held positions respectively holding said valve element in its first and second positions, wherein, as said shaft approaches the respective first and second ends of the stroke, the respective first and second biasing forces are used at least partially to overcome magnetic attraction holding said valve actuating member such that said valve actuating member moves between the first and second magnetically held positions thereby causing the valve element to shift and redirecting the pressurized fluid into the piston chamber to effect reversal of the direction of travel of said shaft.