Toroidal engine

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The Toroidal engine design is a form of internal combustion engine that features pistons that rotate within a toroidal space. To date, no toroidal engine designs have entered production, but the designs are typically simple and have few moving parts, and toroidal engines have a high theoretical efficiency, making them attractive to inventors. Examples include Angel Labs' "Massive Yet Tiny" engine^[1], the Rotoblock^[2], the Roundengine^[3] and designs by Tschudi and Hoose^[4].

____________ Image:Http://archive.aztrib.com/Repository/getimage.dll?path=EVT/2003/03/24/37/Img/Pc0370800.jpg The Rotary Opposed Piston Engine (ROPE) consists of a 4 cylinder, 4 cycle internal or external combustion engine, which is capable of running multiple fuel types. Building a prototype entails a design having the following general characteristics:

Radically increases power density (2 to 8 horsepower per pound) Improve fuel efficiency (Brake Specific Fuel Consumption of .35 to .45) Substantially decreased pollution (Hydrocarbons of 3 parts per million) Lower cost per BHp ($0.75/horsepower in 100,000 unit quantities)

The prototype is a 4 cylinder internal combustion production engine, it would be 65 horsepower. Actual size is 6 inches in diameter, 5.75 inches in length, weight 14.73 pounds. It is roughly the size of a current day car alternator. Compression ratio is 9.5:1 and horsepower per pound is 4.413.

The working prototype is a 4 cylinder, 4 cycle gasoline engine, with a displacement of 4.342 Liters and a 9:1 compression ratio. The block was 6 inches long, 10 inches in diameter. Power displacement was 56% of the total engine volume. That ratio has since been increased to 75% and can actually rise to greater than 100% because the cylinders share a common block cavity volume.

The Rotary Opposed Piston Engine can burn and function with multi-fuel or external heat (steam) driven. If solar produced the hydrogen as the fuelsteam actuates the pistons, using , it becomes totally "Non-Polluting" and operates entirely on a renewable energy source. It will reduce vehicle weight, which further increases fuel economy, reduce overall pollution and consumption of energy and raw materials in production. Where simplification reduces product utility or performance, the ROPE design will radically simplify the mechanical structure of pumps, compressors or engines, forever.

By comparison, a conventional 4 cylinder, 4 cycle engine has scores of moving parts. The ROPE has only two (2) different moving parts, one of which, "Simultaneously" performs the Intake, Compression, Power and Exhaust functions of the four cylinders. Further, this simplification, in addition to reducing frictional losses, provides the engine with the ability to enhance performance by including features not practical or possible in conventional engine designs. They are as follows:

Burn-Dwell (BD): Allows complete fuel burn and heat energy conversion into peak pressure before engine stroke. This enhances power per fuel consumption, or Brake Specific Fuel Comsumption (BSFC), and reduces exhaust emissions. It also allows the engine to operate under lean burn conditions.

BD has not been available to conventional designs since the piston is coupled directly to the output crankshaft and cannot be stopped during fuel burn. The Rhombic Drive in a Sterling engine is the only mechanism currently that comes close. The Rhombic is a compound crank/connecting rod that distorts the normal rectilinear motion of a standard crankshaft/connecting rod arrangement. This device uses many moving parts and sliding surface parts that result in high losses. BD in the ROPE is achieved through a pure rotary motion. The ROPE has approximately 5% of the sliding surface area of a conventional engine.

BD will allow the ROPE to further improve efficiency by mitigating the effects of a high surface area-to-volume burn in the combustion chamber. High surface area-to-volume ratio chambers are inefficient and polluting since a thin film of fuel does not burn adjacent to the surface and causes high hydrocarbon emissions in the exhaust. BD ensures that combustion takes place in the minimum volume at the peak compression ratio. In conventional engines without BD, the fuel is burning as the chamber expands to, and in some cases, after the exhaust valve has opened. This is not the case in the ROPE design. Additionally, the back-to-back configuration of the pistons at compression means that if a long stroke is designed and the pistons have concave faces, the combustion chamber geometry during a BD fuel burn is virtually spherical. Conventional engines have a cylindrical geometry that offers a much worse ratio during ignition. The ROPE spherical combustion chamber is the lowest possible surface area-to-volume ratio possible and hence, the most efficient and least polluting, all other factors being equal.

Either lean air/fuel ratios or BD could be used to achieve a pressure spike at combustion and one or both techniques would enhance efficiency. The lean air/fuel ratio technique has been available to conventional internal combustion engines but has not been exploited. In a conventional design, lean burn conditions result in burned valves from the rapid detonation and a "ping" normally associated with pre-ignition. Cylinder temperature should be lowered through the reduced energy contained in the system during lean burn combustion, but it actually increases due to the complete burn and relatively increased time to energy, allowing for a more complete absorption of the energy. Since the ROPE design is anticipated to benefit from the use of ceramics, it will be capable of operating under the high temperature conditions experienced during complete fuel burns.

Hyper-Expansion (HE): Allows the power stroke Expansion Ratio (ER) to be greater than the intake/compression stroke, or the Compression Ratio (CR). Hyper-Expansion Ratio (HER) is engine power ER/CR. A typical HER for a 9:1 CR is 2.6. This means that the engine power stroke is increased to 2.6 times the volume of the intake reducing cylinder pressure to atmospheric conditions before exhaust. This feature adds power per fuel burned. In a conventional engine, energy is dumped out the exhaust valve. In the ROPE design HE allows the power stroke to be longer than the compression stroke. As a result, the cylinder pressure can be reduced to zero PSIG before reaching the exhaust port. All pressure produced by the fuel burn is applied to the production of power and there is no explosion of energy being released during every exhaust stroke that is heard from conventional designs.

When the engine is designed to operate at a specific compression ratio (Cr), hyper-expansion and horsepower, then a simple port provides the same intake volume to be compressed each time and the cam stroke control determines the minimum volume between pistons so that a fixed HE/Cr engine is achieved. ____________