Patent ID: 8360019

Claim:
A pressure balancing system for an engine ( 10 ), comprising: an engine piston ( 14 ) slidably received within a cylinder ( 12 ) and operatively connected to a crankshaft; an engine valve ( 28 ) including a stem ( 30 ) and a head ( 26 ), the engine valve ( 28 ) operable to engage a valve seat ( 22 ) and control fluid communication between a passage ( 24 ) and the cylinder ( 12 ); and a balance piston ( 44 ) on the stem ( 30 ) of the valve ( 28 ) and movable in an enclosed separate balance cylinder ( 48 ) that together with the balance piston ( 44 ) defines a balance chamber ( 50 ), the balance chamber ( 50 ) being in fluid communication with the passage ( 24 ) via a first balance port ( 52 ) controlled by a first control valve ( 54 ), and the balance chamber ( 50 ) being in fluid communication with a low pressure source via a second balance port ( 56 ) controlled by a second control valve ( 58 ); wherein system is configured such that the first control valve ( 54 ) is closed and the second control valve ( 58 ) is open when the head ( 26 ) of the engine valve ( 28 ) is disengaged from the valve seat ( 22 ), and the first control valve ( 54 ) is open and the second control valve ( 58 ) is closed when the head ( 26 ) of the engine valve ( 28 ) is engaged with the valve seat ( 22 ).