Patent ID: 8151691
Filing Date: 2012-04-10
Classification: F02B,F02D

Abstract:
1. A variable compression ratio piston for an internal combustion engine that drives a crankshaft connected to the piston by a connecting rod and gudgeon pin, the piston operable to move within a cylinder in response to cylinder pressure, the connecting rod and gudgeon pin having a primary channel for carrying oil into the piston, comprising: a two-part piston having an outer sleeve and a gudgeon pin carrier; the outer sleeve being slideable within the cylinder; the gudgeon pin carrier being slideable within the outer sleeve and positioned within the outer sleeve to form an upper chamber between the upper surface of the gudgeon pin carrier and the crown of the outer sleeve and to form a lower chamber between the lower surface of the gudgeon pin carrier and the closing end of the outer sleeve; a spring-loaded seal in the top end of the gudgeon pin carrier that receives the oil from the primary channel and delivers the oil to a first inner channel and a second inner channel within the gudgeon pin carrier; a first entry valve for delivering oil from the first inner channel into the upper chamber; a second entry valve for delivering oil from the second inner channel into the lower chamber; a rate-sensitive relief valve for relieving oil from the upper chamber; wherein the relief valve is a sleeve-type valve having a spring-loaded male element slidebly contained in a dead-ended bore, the male element having a hollow interior and a pressure face at a bottom end of the hollow interior to which pressure from oil in the upper chamber is applied, a spring housed below the male element in the bore, and a bleed orifice providing fluid communication between the pressure face and the portion of the bore containing the spring; wherein the relief valve is configured such that oil may flow from the hollow interior into the portion of the bore containing the spring when the relief valve is closed; and a relief channel for carrying oil from the upper chamber via the rate-sensitive relief valve.