Internal-combustion engines – Valve
Reexamination Certificate
1999-10-25
2001-03-13
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Valve
C123S190100, C123S190800
Reexamination Certificate
active
06199531
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a valve system for use in regulating fluid flow into and out of a combustion cylinder of the type housing a reciprocating piston. More in particular, the intake and exhaust valves associated with the valve system of the present invention are a folding leaf or folding blade type of shutter valve wherein a central aperture is formed when the valves are disposed in an open position for the substantially free, unobstructed passage of fluid flow therethrough. Further, the shutter valves associated with the present invention are computer and/or electronically controlled based on the operating performance and characteristics of the internal combustion engine.
2. Description of the Related Art
Automobiles, boats, airplanes, and other types of motorized vehicles are typically powered by internal combustion engines which are designed to provide energy through a flywheel which is turned by a crank shaft. In the operation of an internal combustion (“I.C.”) engine, a combustible air/fuel mixture is drawn inside a cylinder with the combustion taking place in the combustion chamber located at the top of each cylinder. In each cylinder, a piston, which is connected to the crank shaft through a connecting rod, continuously reciprocates during operation of the I.C. engine. The reciprocation of the piston moving up and down powers the crank shaft. The cyclical movement in an automobile engine is typically termed a “four stroke cycle”. The four strokes of the four stroke cycle are named according to their respective purpose and include an intake stroke, a compression stroke, a power stroke and an exhaust stroke. In order to maximize the conversion of energy produced from the combustion of fuel into mechanical energy, by the piston turning the crank shaft, combustion occurs within the top of the cylinder, wherein the combustion chamber is effectively sealed during combustion.
The intake and exhaust of gases from an internal combustion engine are controlled by intake and exhaust valves respectively, disposed in fluid communication within the combustion chamber. Accordingly, the cylinder head has an intake opening and an exhaust opening for allowing an air/fuel mixture to enter the cylinder and for exhaust to exit the cylinder after ignition and combustion of the air/fuel mixture. In order to maintain the cylinder in a fluid-tight or sealed condition during the compression and power strokes, valves in the cylinder head close the intake and exhaust openings. These valves are accordingly referred to as the intake and exhaust valves.
The intake and exhaust valves operate at different times depending on the cycle of the engine. These valves are normally held closed by heavy springs and increased pressure due to compression within the cylinder. The purpose of a valve actuating mechanism is to overcome the spring pressure and open the valves at the proper time. The valve actuating mechanism includes the engine cam shaft, cam shaft borrowers or tappets, push rods and rocker arms. The cam shaft, which rotates to drive the individual poppet valves, is generally enclosed within the engine block or cylinder head. The cam shaft has eccentric lobes or cams formed thereon such that each of the cams are specifically disposed and configured for predetermined driving engagement with each valve in the engine. As the cam shaft rotates, the cam lobes move up under the valve tappet, thereby exhibiting an upward thrust through the tappet against the valve stem or push rod. This thrust overcomes a valve spring pressure as well as increased pressure within the cylinder and causes the valve to open. When the lobe moves under the tappet, the valve spring reseats the valve resulting in a closing of the valve opening.
During the intake stroke of a four stroke cycle, the intake valve is opened and the exhaust valve is closed, allowing the air/fuel mixture to fill the cylinder. In the compression stroke of the four stroke cycle, both the intake and exhaust valves are closed. In the power stroke, both the intake and exhaust valves are closed and a spark generated by the spark plug located inside the cylinder and in direct communication with the combustion chamber serves to ignite the air/fuel mixture causing its combustion and forcing the piston in a downward direction towards the bottom of the cylinder. In the exhaust stroke of the four cycle engine, the piston travels upward from the crank shaft and the exhaust valve is opened while the intake valve is closed. The upwardly traveling piston forces the exiting of all the exhaust gases from the cylinder. The exhaust gases are a result of the combustion of the air fuel mixture during the previous power stroke. The exhaust gases exit the cylinder head through the exhaust manifold. The four stroke cycle is then repeated numerous times in rapid succession for the powering of the crank shaft.
The duration of the opening and closing of the intake and exhaust valves is fixed, depending on the configuration of the cam lobe which lifts the valve tappets, and accordingly, opens the intake and exhaust valves. The fixed period of time during which the intake and exhaust valves are open is only optimal for one particular revolution per minute (RPM) of the crank shaft. This is generally preset at around 3500 RPMs. However, the amount of the air/fuel mixture, and consequently, exhaust gases, vary depending on the particular RPMs at which the vehicle is operating. The optimal air to fuel ratio is typically recognized as 14.7 parts of air to 1 part fuel. Accordingly, as more fuel is required at higher RPMs, a considerable volume of fuel and air is required to pass through the intake valve. Also, at lower RPMs a relatively small volume of air and fuel is required to pass through the intake valve. However, because the intake valve remains open for a fixed period of time, the air/fuel mixture has a tendency to blow out of the cylinder and pass back into the intake manifold. This phenomenon is known as “blow back”. Therefore, with a pre-defined duration for the valve opening, the intake and exhaust valves frequently stay open too long or not long enough depending upon the RPMs of the engine.
An additional problem associated with the use of poppet valves for the intake and exhaust valves is that they require cavities to be formed within the cylinder head creating a dimpled interior within the combustion chamber. Accordingly, when the spark plug generates the spark used to ignite the air fuel mixture, there frequently exists an uneven flame propagation and some of the air fuel mixture does not combust. Further, the combustion of the air/fuel mixture results in energy which is directed into the valve cavities and away from the piston. Both of these situations result in an inefficient combustion and a loss of energy from the ignition of the air/fuel mixture within the interior of the combustion chamber.
In the simplest terms, the purpose of the intake and exhaust valves associated with internal combustion (“I.C.”) engines of the type set forth above, is to regulate the flow of gases at the proper intervals into and out of the cylinders of the I.C. engines. The mechanisms responsible for setting the working fluids of an engine in motion are the reciprocating parts, which are more commonly known as the “bottom end”. The “bottom end” includes the crank shaft, connecting rods and pistons of an I.C. engine, as generally set forth above. These parts are attached to one another in a manner which converts linear motion into rotational motion for the powering of the crank shaft. When the “bottom end” is in motion, it pulls and pushes working fluid past the valves by creating vacuum and pressure within the cylinders. The vast majority of reciprocating piston I.C. engines use poppet valves which effectively obstruct and are, therefore, restrictive to fluid flow.
The use of poppet valves in reciprocating, I.C. combustion engines dates back over a hundred years. They have long been recognized as the most popular valve design fo
Kamen Noah P.
Malloy & Malloy P.A.
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