Supercharged internal combustion engines

In a supercharged internal combustion engine having at least a manifold and at least one valve, said valve having a valve disk adapted to close a brance of said manifold and a smooth valve stem having an uninterrupted surface, a stationary valve guide having an inner bore slidably receiving said valve stem with a relatively large clearance fit, said valve stem having an end portion whic projects out of said guide into a casing, and valve actuating means located in said casing and cooperating with said end portion of the valve stem, the improvement comprising at least one annular cavity formed in the valve guide around the valve stem and communicating with said inner bore in close proximity to that end of the valve guide which is adjacent the manifold branch, return passage means separate from the clearance space provided by said clearance fit and permanently communicating with said cavity, and oil supply passageway means separate from the clearance space provided by said clearance fit and permanently communicating with said cavity, and adapted to deliver oil to said cavity, whereby in operation oil is permanently and continuously circulated from said oil supply passageway means through said cavity into said return passage means, said oil supply passageway means and oil return passageway means being so proportioned that in operation the static pressure of the oil in said cavity is permanently lower than the pressure prevailing in the manifold branch, said clearance space extending axially in both directions from said cavity to the opposite ends of said guide.

In a valve lubrication system for intake and exhaust valves of a supercharged internal combustion engine having at least one poppet valve and an associated valve guide mounted in the engine, said valve having a stem with a constant diameter portion slidably mounted with a clearance fit in a throughbore of said valve guide so as to define a relatively large clearance space radially between said stem and bore and open at the opposite ends of said guide, said radial clearance space being sufficiently large radially between said stem and bore to enable the valve poppet to center itself onto its associated seat to achieve a gas tight fit therewith when said poppet valve is closed while maintaining said clearance fit of said stem in said bore, the improvement wherein one end of said valve stem remote from the valve poppet protrudes from one end of said guide into a shielded chamber housing valve actuating means cooperable with said stem to reciprocate said valve, first oil supply means for feeding oil into said radial clearance space adjacent said one end of said guide for lubricating said stem in said guide bore, said valve guide having first passageway means disposed circumferentially about and extending radially of said guide between said radial clearance space and the exterior of said guide to thereby define a cavity in constant communication with said radial clearance space, said first passageway means being spaced from the other end of the valve guide which is closest to the valve poppet by a distance measured axially of said stem approximately equal to the diameter of the valve stem, said valve guide having second passageway means constantly communicating said first passageway means with a pressure relief zone wherein the pressure is approximately atmospheric, and second oil supply means comprising an oil supply conduit in constant communication with said passageway means to supply oil via said first passageway means to aid radial clearance space for lubricating at least the portion of said guide bore extending axially from said first passageway means to said other end of said guide by the pumping effect induced by reciprocation of said stem past said first passageway means, said second passageway means serving to conduct oil away from said first passageway means to said pressure relief zone and also serving to prevent gas from flowing along said radial clearance space to said pressure relief zone while permitting the reciprocating movement of the stem to build a lubricating oil film.