Reducing pumping losses during operation at lower engine speeds increases efficiency. An electrohydraulic valve-train link uses a solenoid and check valve to modify lift profile.
When solenoid valve is closed, the link is fully expanded. Slave piston and engine valve follow master-piston and cam motion. If open, fluid flows from hydraulic circuit into an accumulator, decreasing link length.
Control module triggers solenoid to modify valve-lift profile. As camshaft actuates the master piston, it displaces fluid from its hydraulic chamber to the slave piston's chamber. Slave piston acts on the valve to affect delayed valve opening, early valve closing, or defeat valve motion entirely.
Scott Fowler, Jacobs Vehicle Systems, 22 East Dudley Rd., Bloomfield, CT 06002; (860) 243-7601.