Patent ID: 6622669
Filing Date: 2003-09-23
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 the effective length of the connecting rod, and hence the compression ratio of the cylinder, and a hydraulic-operated locking mechanism that is selectively operable to a locked condition for locking the first part to the second part in a position that sets a given effective length for the connecting rod and to an unlocked condition that allows the first and second parts to be relatively positioned to an effective length different from the given effective length; and a hydraulic circuit for operating the locking mechanism comprising a hydraulic pump for delivering hydraulic fluid to the connecting rod, and a hydraulic fluid augmentation source for at times augmenting the delivery of hydraulic fluid to the connecting rod, and a valve; wherein the pump is arranged to supply hydraulic fluid to the connecting rod at least during times when the locking mechanism is not being operated, and operation of the valve is effective to communicate the hydraulic fluid augmentation source to the locking mechanism to augment delivery of hydraulic fluid to the connecting rod for causing the locking mechanism to operate from one condition to the other condition.