Patent ID: 6237556
Filing Date: 2001-05-29
Classification: F01L,F02B

Abstract:
Rotary valve for an internal combustion engine, comprising:a rotor housing having an axial bore and a transfer port arranged to provide fluid communication between the bore and a combustion chamber of the engine;a valve rotor supported for rotation within the bore, the rotor having a cylindrical main body portion which maintains a predetermined small radial clearance gap to the bore surface and having at least one fluid exchange duct terminating in an exchange port on an outer peripheral surface of the main body portion, the rotor, in use periodically enabling and preventing fluid exchange through the duct in accordace with the operating cycle of the engine;and a sealing system, includinga set of sealing rings disposed on axially opposite sides of the transfer and the exchange ports and received pair-wise in respective single annular grooves formed on either one of the main body portion and within the bore, the rings and grooves being dimensioned such that the rings are received with predetermined axial play between themselves and a radial gap is formed above the groove bottom whilst the rings protrude radially from said annular grooves and either one of the radially outer and the radially inner circumferential surface of the rings is in substantially continuous sliding abutment against either one of the bore surface and peripheral surface of the main body portion, thereby bridging said radial clearance gap in circumferential direction of the rotor,two first longitudinal sealing elements received one each in a corresponding longitudinal groove formed on either one of circumferentially opposite sides close to the transfer port within the bore and on circumferentially opposite sides of a discrete ignition surface zone of the main body portion which, in operation of the valve, covers the transfer port during the ignition phase of combustion fluids in the combustion chamber, the first sealing elements protruding radially from said longitudinal grooves into sliding abutment against either one of the bore surface and peripheral surface of the main body portion, thereby bridging said radial clearance gap in axial direction of the rotor, the first sealing elements having a length such as to be received between the sealing rings closest to the transfer port with either one of a predetermined small axial clearance and play fit; anda pressurising system including a pressurised fluid source and conduits arranged and disposed such as to selectively direct a pressurised fluid in between each ring pair thereby to bias, at least during the ignition phase, the rings in axially opposite directions to abut against a respectively adjacent side wall of the annular grooves in which the sealing ring pairs are received, substantially isolate the transfer port from the annular grooves during the ignition phase and substantially minimise fluid leakage during this phase from the gap cavity defined between the portions of the sealing rings closest to the transfer port and of the first sealing elements that bridge the radial gap, and the facing surfaces of the bore and the main body portion.