Sealing means for rotary valves

A rotary valve of an internal combustion engine having a cylindrical valve, bearing means at each end of said valve supporting said valve for rotation in a bore of the cylinder head of the engine with a small radial clearance between the valve and the bore and means of communication between the combustion chamber and the small radial clearance, oil for lubrication of said bearing means, oil sealing means axially inboard of said bearing means arranged to prevent the axial inward leakage of said oil through the small radial clearance to the combustion chamber, a space between said bearing means and said oil sealing means containing oil, and gas sealing means axially inboard of said oil sealing means arranged to minimise outward axial leakage of gas from the combustion chamber through the small radial clearance, characterised in that each gas sealing means consists of at least one circumferential sealing element of the piston ring type housed in at least one circumferentially extending groove formed either in the periphery of the valve or in the bore of the cylinder head and radially preloaded against the surface of the other, each oil sealing means consisting of a non-rotating annular member also having a small radial clearance to the bore of the cylinder head, second sealing means sealing the small radial clearance between the annular member and the bore, an annular cavity lying peripherally in the small radial clearance and extending between the circumferential sealing element and the second sealing means, the annular member having a substantially radially disposed face arranged to seal slidingly against a radially disposed face on the valve, spring means acting on one end of the annular member to urge the radial face of the annular member against the radially disposed face on the valve.