Model-based control of a solenoid-operated hydraulic actuator for engine cylinder deactivation

Claim 1

A control method for an actuator that disables a valve lifter for a specified engine cylinder to deactivate such cylinder, said actuator including a solenoid-operated fluid valve, a hydraulic sub-system having a control chamber, and a hydraulically actuated locking mechanism coupled to said control chamber, wherein application of a system voltage to said solenoid-operated fluid valve couples a pressurized system fluid to said control chamber for application to said hydraulically actuated locking mechanism to disable said valve lifter, the control method comprising the steps of: estimating a first response time corresponding to a time required for said solenoid-operated fluid valve to couple the system fluid to said control chamber following the application of said system voltage to said solenoid-operated fluid valve; estimating a second response time corresponding to a time required for a fluid pressure in said control chamber to reach a predetermined level once the solenoid-operated fluid valve couples the system fluid to said control chamber; estimating a third response time corresponding to a time required for said hydraulically actuated locking mechanism to disable said engine valve lifter once the fluid pressure in said control chamber reaches said predetermined level; determining an overall response time of said actuator according to a sum of said first, second and third response times; and applying said system voltage to said solenoid-operated fluid valve at a time based on the determined overall response time, relative to a desired time for disabling said valve lifter.