Internal-combustion engines – Valve – Rotary
Reexamination Certificate
2001-04-18
2003-02-04
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Valve
Rotary
C123S0800BB, C123S568130
Reexamination Certificate
active
06513475
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to internal combustion engines, and more particularly, to an internal combustion engine utilizing a rotary valve for directing the flow of intake air into the cylinders and exhausting gases from the cylinders.
BACKGROUND OF THE INVENTION
Increasing concerns about the impact of the internal combustion engine on global warming are putting added pressures on the automotive industry to develop more environmentally friendly engines. Generally, the approach is to increase the fuel economy of the engine by reducing the displacement in efforts to burn less fuel. This small displacement engine would be used as a stand alone power plant or as the principal source of power in an electric hybrid configuration. Currently, the most promising approach is to use the most efficient internal combustion engine, the direct injection diesel, and reduce its displacement to as small as operationally possible. It is in this application and as a small cylinder displacement stand alone power source that the Rotary Valve Diesel (RVD) is expected to be particularly well suited.
Previous art on the RVD attempted to reduce emissions by using the same strategy used decades ago with the Otto gasoline engine to increase fuel economy. Thus, as stated above, the displacement of the engine was decreased in an effort to burn less fuel per mile which also would result in reduced emissions. However, this small displacement engine would encounter the same problem as with the Otto engines, namely, reduced output. The RVD again used the same strategy of increasing rpms' to increase output as was done earlier with the Otto engine. Also, some modest increase in efficiency due to improved thermodynamic and volumetric efficiency would add to this output. This increased power would increase consumer acceptance of the engine and with that, both fuel consumption and emissions would decrease.
While the RVD exhibits many advantages over conventional diesels when attempting to build small cylinder displacement engines, it still does not dramatically reduce either emissions or the characteristic diesel noise associated with the—fast burn phase of combustion in comparison to conventional diesels of similar displacements. The diesel noise is potentially problematic because of consumer aversion to this condition.
The art now presented makes major improvements in the reduction of both noise and emissions as well as reductions in cost while increasing durability. A new feature, the Peak Pressure Reducing Valve (PPRV), can reduce or prevent the spike in pressure and temperature by opening a valve during the rapid burn phase of the combustion cylinder and instantly transfer this heat and pressure to the compression cylinder. First, this reduces noise and second it reduces NOx. The PPRV reduces NOx by preventing its creation and performs like an EGR system allowing for the reduction of any NOx that is produced.
The PPRV also reduces HC emissions. HC emissions are produced by incomplete burning in crevice spaces. Most of the crevice spaces in the RVD are located above the piston, around the seals, and above the top most piston ring. Being that the combustion bowl is off center and the opening for the PPRV is at the point located in the seals closest to the center of the engine, the area of greatest concentration of HC emissions is this very same area from which the combustion gas is drawn while the piston is still relative close to the valve. These gases are passed to the cylinder in the compression cycle to become part of the charge to be burned during the next combustion cycle.
Also reducing NOx is the cooled EGR system located on the rotary valve. Adding to reduced emissions is the cooling of the intake charge by the cooling fins placed on the valve housing. A second benefit of cooling the intake charge is an improvement in volumetric efficiency.
Also increasing efficiency is the PPRV. Thermal efficiency should be improved due to the mixing of gas in both the compression and combustion cycle cylinders ultimately creating more complete combustion. This mixing is due to the very rapid exit of gas from the combustion cylinder and injection into the compression cylinder creating turbulence in both cylinders. Another feature increasing efficiency is the thermal transfer plate which transfers heat via conduction from the power stoke to the compression stroke. Both the PPRV and the thermal transfer plate are positioned not to operate until the intake is fully closed. Heat energy is now added to the compression cycle by both elements. This added heat energy is then present at the beginning of the combustion cycle allowing more reliable and quicker ignition. This is especially important as cylinder displacement is reduced and would allow the RVD to operate in cylinder displacements smaller than conventional diesel engines.
Finally, the last two features increase durability. First, the valve shape is changed to a more “bell” shaped configuration and made smaller making it stronger. Lastly, the seal system is changed adding a double piston type seal around the valve. This in combination to the seals on the block allow the double sealing of the initial 60% to 65% of the power stroke.
The last point to be addressed is the use of ceramics or ceramic coatings on the RVD. While this technology can also be used on conventional engines, it should be less costly when used on the RVD. This would be due to fewer parts being affected and the parts affected being relatively easy to coat. In the RVD the same exhaust serves several cylinders and therefore has more heat available to burn soot. This effect can be increased at relatively low cost by coating the exhaust with ceramics.' An additional benefit of this coating would be less heat transferred to the intake charge. Similarly, a ceramic coating on the bottom of the valve would also reduce heat transfer and increase the durability of the valve. Coating both of these elements would be the start of making the RVD a low heat rejection engine.
All the improvements of the RVD are intended to allow a small cylinder displacement diesel to replace the Otto gasoline engines of the same power. The RVD could be used in the preferred embodiment of one rotary valve serving four cylinders or in engines having multiples of four cylinders. Potential markets would include light auto and truck, outboard marine, motorcycles, and light aircraft to name a few. However, given that the RVD appears to have significant emissions and noise advantages, it would be expected that the RVD technology would be applied to Diesels of ever increasing cylinder displacement engines. Therefore the potential market for the RVD is huge. Correspondingly, the potential for fuel savings and reduction in emissions and greenhouse gases is very significant.
SUMMARY AND OBJECTS OF THE INVENTION
The present invention is an internal combustion engine having at least one cylinder. A rotary disk valve is located over the top of the cylinders for rotation about an axis parallel to the axis of the cylinders. The center of each cylinder is equally spaced from the axis of rotation of the rotary disk valve. The valve includes an intake passage for directing intake air into the cylinders and an exhaust passage for exhausting combustion gases from the cylinders. The intake passage and exhaust passage in the rotary valve communicate with each cylinder in succession as the valve rotates, allowing the use of a single valve to serve multiple cylinders. The rotary valve uses piston type seals to prevent the movement of gas from the cylinders past the valve. This valve seal is well lubricated by an oil nozzle to produce a tight seal with minimal friction. Another set of seals is located around the major portions of the tops of each cylinder to prevent the movement of engine gases between cylinders.
In another aspect of the engine, the intake and exhaust valve openings as well as the intake and exhaust passages are increased in size by at least 40% over conventional poppet valve engines. This not
Coats & Bennett P.L.L.C.
Kamen Noah P.
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