 The NWERA rotary engine is distinctly different from the many rotary engine concepts which have gone before. Since the time of the steam engine engineers have attempted to create a viable rotary engine in part because a larger moment arm can be produced at the outer extents of the rotor than can be produced with the rotating crankshaft. Additionally a rotary engine will operate more smoothly because of the absence of reciprocating mass. Although hundreds of rotary engines have been patented, none has ever been produced commercially with the exception of the Wankel rotary, which is in fact not a true rotary because it requires reciprocating mass similar to a piston engine.
Rotary engines offer a marked increase in torque potential, because the combustion charge is acting against the pressure surface at a constant distance from the center shaft. Additionally, in a balanced rotary engine, where equal and opposite charges act on the rotor, all of the thermal expansion is translated into useful work. No transverse force is imposed on the main power shaft (This part seems repetitive to the part in blue above) The principal advantage of a rotary engine – that of maximizing torque potential during the entire expansion cycle – is lost in the Wankel engine.
Technology Advantages in the NWERA Rotary Engine
The reciprocating piston engine has been the principal type of internal combustion engine
in use for land-based vehicles for over one hundred years. Although many advances have been made in combustion efficiencies, the fundamental thermodynamic and mechanical drawbacks are unchanged. Principal drawbacks are listed below.
a. Thermodynamic - The physical volume of the chamber is necessarily the same for the compression cycle and the expansion cycle. The end result of this volumetric limitation is that any excess pressure which remains in the cylinder at the bottom of the piston stroke must be exhausted to the environment as both waste heat and pressure (noise).
b. Mechanical – At maximum combustion pressure, the crankshaft angle is such that there is minimal torque produced. Maximum torque for each individual cycle is only realized for a brief period of time, and that when the combustion volume is already half-expanded. Superimposing the moment arm produced as the crankshaft rotates from top dead center to bottom dead center on the P-V diagram shows that the work which can be extracted from the combustion charge is in fact limited to somewhere around 30%. Small gains have been made in diesel engines through the use of piezoelectric injectors and common rail injection systems. This affords ‘charge shaping’, or matching the pressure peaks to the maximum crankshaft offset. However, this effect is small compared to a rotary design which provides a constant moment arm for the entire duration of the expansion cycle.
Otto and Diesel cycles with crankshaft moment arm superimposed on lower isotherm
Potential torque of a piston engine at various points in the cycle.
Utilizing careful design and construction the NWERA rotary engine is simpler than a similar piston engine despite separation of the various functions. Additionally, the design is scalable to meet the requirements of numerous market segments far beyond just automobiles, from light engines up to the prime movers of the world’s freight. By being able to address a broader market, the reduction of global fuel consumption and environmental pollution can be multiplied many times over what can be achieved in only the automotive sector.
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