Internal-combustion engines – Valve – Rotary
Patent
1998-03-20
1999-08-24
Kamen, Noah P.
Internal-combustion engines
Valve
Rotary
1231906, 1231908, 123 80BA, F01L 700
Patent
active
059412062
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an improved rotary valve for internal combustion engines, and in particular to an improved arrangement of sealing elements for rotary valves.
1. Background of the Invention
There have been proposed different kinds of rotary valve assemblies for internal combustion engines. Of those kinds, the present invention is particularly concerned with rotary valves comprising a cylindrical or sleeve-like rotor body having separate intake and exhaust passages beginning in opposite axial sides of the rotor body. The passages terminate in an inlet and exhaust port, respectively, angularly spaced apart on the peripheral surface of the rotor body. The ports are dimensioned and arranged with respect to one another such that upon rotation of the valve rotor in a cylinder head valve bore, in which the rotary valve is rotatably supported to maintain a small clearance gap between facing surfaces of the bore and rotor body, the inlet and exhaust ports periodically align with and pass over a single transfer port in the bore surface of the cylinder head. The transfer port is in fluid communication with a combustion chamber of the engine. Periodical and properly timed opening of the transfer port allows passage of a specified air or air-fuel mixture amount, depending on whether the fuel supply is by means of injection or by a carburetor, through the valve rotor into the combustion chamber and expulsion of exhaust gases therefrom into the exhaust manifold during the induction and exhaust strokes of the engine. The circumferential surface of the valve rotor serves to close the transfer port during the combustion and compression stroke of the cycle and ideally should provide a leak-free closing of the transfer port during this part of the cycle.
2. Prior Art to the Invention
A number of different sealing systems for rotary valves have been proposed to maintain the transfer port sealed-off during the compression and combustion phases of the operating cycle of the engine.
It should be noted that some sealing systems are based on maintaining the smallest possible clearance gap between the circumferential outer surface of the rotor and the surface of the valve bore. While such sealing systems also incorporate additional sealing elements e.g. wear and temperature resistant O-rings, sealing is in essence to be achieved by the smallest possible gap size and only secondarily by sealing element interaction with the rotor and bore surfaces.
However, rotary valves relying on such sealing mechanisms have not proven successful. The present invention is not concerned with such rotary valves, but with those where a relatively small, clearance gap is maintained between facing circumferential surfaces of the rotor body and bore which does not tend to suppress gas flow, as is further described below. This radial gap has a major impact on how a sealing system can be implemented.
There are a number of published patent applications by A. E. Bishop Research Pty. Ltd. (U.S. Pat. No. 4,852,532 and WO94/11621) and Dana Corporation (U.S. Pat. No. 4,019,487) relating to rotary valves with small clearance gap and which describe seal systems providing a so called "window of floating seals". The seal system is aimed at preventing high pressure gas loss through the transfer port past the gap zone between the valve rotor and valve bore above the port during the combustion and compression cycle.
U.S. Pat. No. 4,852,532 discloses a seal system consisting of two axially spaced apart ring seals which are received in annular grooves within the valve bore, the ring seals being pre-loaded so as to rub against the outer peripheral surface of the rotor body on either side of the inlet and exhaust ports. The ring seals sealingly close the annular gap between valve rotor and valve bore along the bore axis. The system also comprises two axially extending sealing bars which are located in grooves in the valve bore surface on either circumferential side of the cylinder-head transfer port. The sealing blades are biased agai
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Smith Brian
Smith Wayne
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