Solenoid valve control for noise reduction in a variable valve lift system

A variable valve lift system for an internal combustion engine, the system comprising:

• a solenoid valve configured to selectively fluidly connect a middle pressure chamber to a high pressure chamber, the high pressure chamber configured to actuate an engine valve of the internal combustion engine;
• and,
• a controller configured to:
• i) determine a fluid intake opening timing of the solenoid valve by comparing a measured hydraulic fluid supply pressure of the middle pressure chamber to a critical hydraulic fluid supply pressure, the fluid intake opening timing configured to facilitate replenishment of the high pressure chamber from the middle pressure chamber during or after a valve lift event of the engine valve during operation of the internal combustion engine, and ii) open the solenoid valve according to the determined fluid intake opening timing;
• and
• the solenoid valve configured to be fluidly connected to a first pump and a second pump.

A variable valve lift system for an internal combustion engine, the system comprising:

• a solenoid valve fluidly connected to at least one first fluid gallery and at least one second fluid gallery, the solenoid valve configured to provide, in an open state, hydraulic fluid refilling of the at least one second fluid gallery by the at least one first fluid gallery, or hydraulic fluid flow from the at least one second fluid gallery to the at least one first fluid gallery;
• and,
• a controller configured to:
• i) determine a fluid intake opening timing of the solenoid valve by comparing a measured hydraulic fluid supply pressure of the at least one first fluid gallery to a critical hydraulic fluid pressure, and ii) open the solenoid valve according to the determined fluid intake opening timing;
• and
• the fluid intake opening timing configured to occur when a crankshaft of the internal combustion engine is being powered by combustion pressure of the internal combustion engine.