Rotary engine design needs working prototype
Countless rotary engine designs have been submitted to Eureka over the years, most falling by the wayside, but one recent development looks promising, writes Dean Palmer
Private inventor, Stephen Harding, has developed a compression ignition, direct injection engine for power generation and automotive applications that, he claims, "addresses the need to drive down cost and weight in internal combustion engines, as well as lowering CO2 emissions."
The engine, which requires investment or funding to take it from the modelling and simulation stage to a full working prototype, also promises excellent low-end torque, fast throttle response, turbine-smooth operation and meets the US Environmental Protection Agency's 2010 Nox/PM limits relating to diesel engines.
As Harding told Eureka: "There are no pistons, con rods or crankshaft. Instead, single-lobe cam rotors mounted on the output shaft are turned by gas or roller pressure on their surfaces, or a combination of both. All rotating parts can be perfectly balanced and starting accomplished at any degree of rotation of the output shaft. The engine can run on various fuels, including hydrogen."
The basic engine option has one power module and a compressor. The latter compresses air from atmosphere and delivers it to the power module, direct or via a buffer chamber with provision for intercooling. The power module then inputs the compressed air through a rotary valve, injects fuel and delivers the combustion and exhaust strokes. Only the power section of the engine needs to be strong enough to handle the peak pressures, so significant weight savings can be made elsewhere.
When questioned about the well-documented design problems associated with rotary, Wankel-type engines, Harding replied: "The engine has a precision conjugate cam mechanism that is able to position the curved vanes so that their tips follow the cam profiles with less than one micron clearance if necessary. This will prevent any tip wear. If I choose to use contact seals, some friction will arise, but this will not be anything like the problem it is with the Wankel engine."
In the schematic given to Eureka (pictured) the vanes are long and curved, but Harding said, in practice, the vanes would each be supported by two webbed arms, one at each end, supported their entire widths to prevent any deflection under high pressure loadings.
Any interested parties should contact stephenharding@estl.demon.co.uk
