A hydraulic manifold assembly for variable actuation of engine valves in
accordance with the invention includes oil flow galleries. Engine oil
under pressure communicates with a global supply gallery in the manifold
assembly, from which pressurized oil is supplied selectively via
individual supply galleries to each variable actuator for each valve
through the action of solenoid valves. At engine startup, all galleries
may be empty of oil, or partially filled. A global relief valve at the end
of the global supply gallery causes air to be purged immediately upon
startup of the engine. Each solenoid and individual gallery is provided
with a low pressure relief valve leading back to the crankcase when the
solenoid supply valve is closed. A bleed orifice between the global supply
gallery and each individual gallery continually bleeds oil under low
pressure into the individual gallery, which purges initial air therein.
Anti-draining means in each individual gallery keeps the gallery filled
when the valve deactivation mechanism is deactuated.
