Ebco Industries, under contract to REGI US, is implementing the same set of modifications done on the 42hp Rand Cam sliding-vane rotary engine on the diesel, 125hp version of the Rand Cam. (Earlier post.)
The modifications include vane design to eliminate sealing and six additional cam designs with a special coating to ensure durability. The company expects these to be complete within 30 days, and will then begin an engine testing program to assess endurance, maintenance factors and fuel efficiency.
The 42hp version earlier entered testing for a genset application for a series hybrid vehicle and for an unmanned aerial application.
Invented by James McCann in 1983, the Rand Cam uses a disk-shaped rotor with two or more axial vanes mounted perpendicular to the direction of rotation. The vanes slide back and forth against cam surfaces to alternatively expand and contract the chamber volume.
Through the process of these sliding vanes, combustion chambers form between the rotor, stator walls and vanes where the fuel/air mixture is injected, compressed, combusted and exhausted. (Sealing is an issue that Rand Cam is working to resolve with the modifications.)
Increasing the number of vanes increases the number of combustion events throughout a revolution. The original Rand Cam had two; the current version has 12.
The engine operates at lower speeds than a typical Wankel engine (less than 2,000 rpm) and at higher compression ratios: 15 and 20 to 1.
The engine is compact (the 42hp diesel is 6" in diameter and 6" long), and offers 30% volume efficiency, according to the company, compared to the Wankel engine’s 10% volume efficiency.