Sealing Improvement

Historically, sealing of the combustion chamber is one of the major challenges of rotary engines. Gas escapes through leaks due to tolerances (geometric leaks) and through leaks from the movement of the seals (dynamic leaks). In X-engines, inter-chamber leaks are sealed by two apex seals, while the two face seals prevent leaks past the rotor and the housing. Because of thermal expansion, rotor movement, and manufacturing tolerances,  there is a large geometric leak (see image on left). This accounts for the majority of lost mass inside the chamber and lowers efficiency and power significantly. As a result, reducing this geometric leak is a company priority.

Geometric leakage was reduced in new iterations by limiting the outer dimensions of the face seal and by imposing difficult tolerances on the rotor profile and seal height. To improve upon this design, I devised a concept where the face seal rested on the outer profile of the rotor. A new set of radial seals contact directly against the face seal. In this design, the height of the radial seals could be easily matched to the height of the face seal via surface grinding—reducing geometric leakage to near zero. A secondary face seal was added to reduce dynamic leakage. These changes lowered engine leakage to that of a piston engine and resulted in a significant increase in power. I am proud that my design was able to make such an improvement to performance, while eliminating several tight tolerances.