Internal-combustion engines – Valve – Rotary
Reexamination Certificate
1999-11-02
2001-10-30
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Valve
Rotary
C123S190800
Reexamination Certificate
active
06308677
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable
REFERENCE TO A MICROFICHE APPENDIX
Not applicable
1. Background of the Invention
The present invention relates broadly to internal combustion engines and, more particularly relates to a rotary valve assembly with improved sealing, seals and bearings.
Considerable effort has been spent in development of rotary valve arrangements for internal combustion engines. This effort has been reasonable because of the basic inefficiency of reciprocating or poppet valves that have been almost exclusively utilized for such engines. The poppet valve, quite similar to a stop check valve, in operation substantially interferes with fluid flow in that the valve head is in the flow path of the gases resulting in streamline distortion that significantly reduces and restricts the fluid flow, into or out of a cylinder. Furthermore, mechanical actuation of poppet valves accomplished by depressing the valve stem by a rocker arm and/or a cam, represents an additional energy loss in view of the numerous components that are necessary for operation. While a cam in cylinder head of the engine eliminates the push rods that are otherwise required, the cam does include levers and springs for maintaining the valves in a closed position. The levers and springs require expenditure of a certain amount of energy for operation that further reduces engine efficiency. This type of engine valve is disadvantageous due to its higher of manufacturing cost which results primarily from the assortment of components required for the valve and its actuation. Additionally this valving system has limitations on speed and endurance.
Rotary valve engines are generally recognized as variations on conventional internal combustion engines. Rotary valves have advantages over poppet valve arrangements, which exceed those of the most sophisticated multi-valve poppet arrangements. Because rotary valves have unhindered flow, thus enhance the power output of the engine, they offer a full port to the combustion chamber, instead of a port partially blocked by a poppet valve, which obstructs the flow, induces a pressure drop, and reduces intake and exhaust flow efficiencies. To provide the same power output with tappet valves, due to higher friction and flow coefficients, it would be necessary to provide as many as four inlet valves per cylinder.
Rotary valve systems, known to have been developed for internal combustion engines are either comprised of elongated tubes that connect with several cylinders or disc-type valve elements disposed in each cylinder. Neither of these tapes of rotary valve mechanisms have been found to be as effective or as efficient as desired or possessing sufficient advantages over the reciprocating valves.
There is a need in the art for a rotary valve engine that does not leak and provides exemplary service. There is also a need in the art for a rotary valve engine that is capable of being manufactured more economically.
2. Description of the Prior Art
A rotary valve engine is another previously known valving in which a cylindrical valve member is mounted within the engine housing in the fuel intake or exhaust passage means for the engine cylinders. Through bores are provided through the cylindrical valve member so that upon rotation, in synchronization with the crankshaft and pistons, the valve members permit fluid flow through the intake or exhaust passage means via the through bore at preselected rotational positions of the valve member. This valve train is more simple, in that there are fewer moving parts.
Despite the advantages of those rotary valves, such valving systems do not have widespread use or acceptance in the industry. One reason for this is that those rotary valves, and particularly the exhaust portions, are subjected to high temperatures from the engine cylinders and tend to warp when overheated. Warpage of the rotary valve not only disables the engine, but also requires a more expensive overhaul.
A further disadvantage of those previously known rotary valves is that the valves must be placed in precision bearings designed for higher temperature. The bearings are expensive, and are required to withstand the normal engine operating temperatures to which the rotary valve is subjected.
A still further disadvantage of those previously known rotary valves is that the sealing means has been known for inadequately sealing those rotary valve to the engine housing particularly after long usage. As a result, those types of rotary valve suffer from fluid leakage around the valves, which causes engine compression loss and intake blowback.
Examples of rotary valve engine patents include Lockshaw U.S. Pat. No. 4,016,840 and Guenther U.S. Pat. No. 4,036,184. Even with those varied and different approaches, a problem with those rotary valve engines, a problem shared with many rotary components, is that of sealing. Those rotary valve engines can leak if the tolerances are loose enough to permit free rotation, yet closer tolerances make the engine seize.
In the case of U.S. Pat. No. 4,517,939. Kruger May 21, 1995, die use of dry seals are being utilized in a rotary valve arrangement for an internal combustion engine, comprising an intake gas passage and an exhaust gas passage a rotary valve, and a plurality of dry-bearing sealing rings retained in grooves surrounding the valve member and axially adjacent to the ports in the valve member, where the dry-bearing sealing rings have an anti-friction material on the sliding surface, that valve arrangement further comprising at least one heat resistant dry surface bearing seal provided between the valve member and the housing in the spaces between the dry-bearing sealing rings so as to inhibit leakage of gases . That arrangement adds to the expense and fragility, of the seals and complexity of manufacturing. The abrasive self-cleaning surfaces can induce metal contamination into the lubricant and contaminate all engine parts.
A proposal to the sealing problem is found in the U.S. Pat. No. 4,119,077, Vallejos, which applies a rather complex mechanism to one of the sealing problems. Those sealing problems can occur between cylinders along the rotary valve members. Sealing problems can occur between the combustion chamber and the valve member itself when the ports in the valve member have rotated out of registry with the port in the cylinder head leading to the combustion chamber. However effective the Vallejos sealing mechanism appears to be, an elaborate mechanism and higher expense are needed to achieve the basic sealing.
Still another rotary valve arrangement is presented in U.S. Pat. No. 5,372,104 issued to Bill E. Griffin, Dec. 13, 1994. That is a valve body that is rotated, and located within a valve sleeve. Sealing members and rings positioned into a valve rotor and which encircle the valve rotor. Only the sealing members and rings contact the inner surface of the valve sleeve and thus prevent the valve rotor from contacting the valve sleeve. The sealing members are biased by springs to assure that the sealing members maintain contact with the inner surface of the valve sleeve. Those requires more parts, manufacturing processes and further complex methods of sealing.
The present invention is differentiated from the previously referred to rotary valve configurations in that it is comprised of a single valve spool, (although individual spools can be used for intake and exhaust) and it does employ a commercially available, minimally oil lubricated, sintered metal antifriction valve sleeve with a coating of polytetrafluoroethylene (PTFE) on the bearing, that transfers to the valve shaft, lowering the friction and aids in the sealing capability of the spool against the surface seal sleeve bearing. Moreover, this overhead rotary valve provides simplified, effective method of construction, induction, evacuation, and lubrication and with fuel injection, fuel stratification.
Since the instant invention is made with materials those coefficient of thermal expansion is similar to that of the housing (c
Bohach Christopher Scott
Bohach William Louis
Argenbright Tony M.
Bohach Christopher Scott
Bohach William Louis
Harris Katrina B.
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