Legacy Engine Technology

The Legacy Engine can best be described as a planetary rotary engine comprised of a central rotor and orbiting elements, named RoTons. The following figure depicts the configuration of the Legacy Engine with the major components labeled. The figure also illustrates the symmetric processes occuring on the three faces of the three RoTons which allow the engine to execute nine complete thermodynamic cycles per revolution.

The geometry of the Legacy Engine is such that the volume of the combustion chamber increases with shaft rotation in a manner quite different than a piston/crankshaft engine. This feature results in the predicted increase in efficiency from the air standard model described below, which is due to higher pressures during the expansion process.

 

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Beyond the gains in efficiency predicted by the air-standard models, the geometric features of the engine also provide a unique combustion chamber that enables a unique combustion process. As the Roton reaches the minimum volume position, the working volume is divided into two separate volumes, the leading volume and trailing volume, as shown in the adjacent figure. The fuel injection is initiated into the leading volume shortly after the volume divides and continues as the Roton moves across the peak in the housing shape. The trailing volume contains only compressed air that is forced into the leading volume as the Roton continues to move past the peak in the housing. This air enters the leading volume with high levels of turbulence as it is forced through the narrow clearance between the Roton and the housing. This feature enhances the combustion process in the Legacy Engine in two ways. The fuel/air mixture in the leading volume can be closer to stoichiometric to enhance ignition, while the over all operating mixture can remain lean as is typical for compression ignition engines. The high levels of turbulence in the air that is forced from the trailing volume would promote good mixing, therefore resulting in more efficient combustion.

In the Legacy Engine, the pressure forces due to combustion are applied to the output shaft directly as torque; there is no reciprocating-to-rotary mechanism required to apply torque, as is the case for a conventional piston/crankshaft engine. This eliminates the inefficiencies associated with friction due to thrust loading of the pistons and provides a much improved vibration characteristic.

Aspiration of the Legacy Engine is accomplished with ports rather than valves. This eliminates a complex subsystem, which lowers cost and improves reliability.

The Legacy Engine can easily be configured as either shaft-horizontal or shaft-vertical. This feature can provide increased latitude in the design of the downstream power transmission component as well as packaging options.

Many of the components of the Legacy Engine are made up of simple geometry- surfaces of revolution or extruded profiles. These simple shapes allow application of advanced materials such as ceramics and composites, which are difficult to implement in the complex geometry of conventional engines.

Overview

The Legacy Engine can best be described as a planetary rotary engine comprised of a central rotor and orbiting elements, named RoTons. A brief description of the operation of the engine is included for clarity. Figure 1 depicts the configuration of the Legacy Engine with the major components labeled. The RoTons do not rotate with respect to the housing; they orbit, in the same angular orientation, along with the rotation of the rotor.

Figure 1 Legacy Engine configuration

Figure 2 illustrates one complete cycle (one full rotation of the rotor) for a working volume associated with a single face of one RoTon. The working volume versus rotor angle plot is labeled to indicate the four processes required for engine operation. The gas exchange processes are indicated by flow arrows in the direction of the scavenging flow. Representative positions of the rotor and RoTon, as well as the working fluid for the processes, are indicated.