Patent ID: 6497203
Filing Date: 2002-12-24
Classification: F02B

Abstract:
A variable compression ratio engine comprising a connecting rod via which a crankshaft that rotates about a crank axis reciprocates a piston within a cylinder, wherein the connecting rod comprises:a first part and a second part that are relatively positionable to set an effective length of the connecting rod and hence a compression ratio for the cylinder; a first locking mechanism that is resiliently biased to an unlocked condition unlocking the first part from the second part when the two parts are in a position that sets a given effective length for the connecting rod to allow the two parts to be relatively positioned to a different effective length from the given effective length but that is operable to a locked condition for locking the first part to the second part; a second locking mechanism that is resiliently biased to a locked condition locking the first part to the second part when the two parts are in an effective length position different from the given effective length position but that is operable to an unlocked condition that allows the first and second parts to be relatively positioned from the effective length position different from the given effective length position; a first passage for delivering hydraulic fluid to the first locking mechanism to operate the first locking mechanism from its unlocked condition to its locked condition in consequence of flow of hydraulic fluid to the first locking mechanism when the two parts are in the given effective length position; and a second passage for delivering hydraulic fluid to the second locking mechanism to operate the second locking mechanism from its locked condition to its unlocked condition in consequence of flow of hydraulic fluid to the second locking mechanism when: the two parts are in the effective length position different from the given effective length position.