Controlled Combustion Engine

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Controlled Combustion Engine (CCE) is a type of internal combustion engine designed by Brad Howell-Smith in 1995. It uses two counter-rotating cams instead of a crankshaft driving two horizontally opposed pistons [1] while retaining an identical cylinder head assembly to conventional engines.

It is around a quarter the size and weight of a conventional engine of similar output and uses fewer moving components. A four or two stroke cycle can be used and it can run on petrol, diesel, compressed natural gas or ethanol.

During the power stroke, maximum mechanical advantage is reached after the piston has moved approximately 5% of its travel from top dead centre (approx. 10° ATDC), which makes better use of the high cylinder pressures at this point in the cycle. In comparison a conventional engine reaches its maximum mechanical advantage after the piston has moved approximately 40% of its travel from top dead centre (approx. 60° ATDC). A side affect of this is a CCE can idle at a much lower RPM. In an independent analysis, torque output was shown to be 2.9 times greater than that of a conventional engine [2].

Because the piston assembly only moves in one dimension (unlike the case in an engine with connecting rods), contact with the cylinder wall is minimised, which reduces wear and lubrication requirements. The cams create less piston shock, which allows ceramic components to be used. The counter-rotating nature of the cams means that most rotational forces are cancelled, which eliminates the need for a heavy flywheel. The engine can run in either direction if symmetrical lobes are used.


The idea came to Howell-Smith, an automotive engineer residing in Australia, during REM sleep. He designed five different engine layouts with variations on each and established Revolution Engine Technologies Pty Ltd in 1996 with a budget of A$2000. The first working prototype was built by father-in-law Peter Koch in Howell-Smith's garage. Howell-Smith founded a company named Revetec Limited and set up a research and development site in Sydney. The prototype was displayed at the 1996 Sydney International Motor Show which brought public awareness to the design. Work began on a second prototype intended for use in generators and pumps, however interest expressed by the Middle East automotive market shifted focus towards automotive applications. Revetec's business model is to license its technology to engine producers worldwide.

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Piston engine configurations
Straight Single, 2, 3, 4, 5, 6, 8, 9, 10, 12, 14
V 2, 4, 5, 6, 8, 10, 12, 16, 20, 24
Flat 2, 4, 6, 8, 10, 12, 16, H
W 8, 9, 12, 16, 18
Other inline H, VR, Opposed, U (Square), X
Other Hemi, Radial, Rotary, Pistonless, Deltic, (Wankel)

Heat engines
Stroke cycles
Engine types
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Piston layouts
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Motion mechanisms
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Thermodynamic cycle