Covaxe Limited engine brings together the concepts of the barrel or axial engine, the Opposed Piston engine and new, patented techniques to provide a low carbon, low emissions internal combustion engine that promises to be disruptive technology for the 21st century.
Axial/barrel engines have been around since around 1910 but have never seriously challenged traditional crank-based ICEs, so one might reasonably ask what has changed? The problems with axial engines have been (i) achieving a durable mechanism to convert the linear piston force into torque, be this a swash plate, cam or Wobble plate, and (ii) difficulty of assembly and disassembly for maintenance. Advances in tribology and computational analysis enable us to have confidence in solving the first of these challenges and a Covaxe-patented modular cylinder approach overcomes the second. The axial engine architecture allows us to implement our constant volume combustion cycle, delivers extremely low vibration in a convenient quasi-cylindrical package, and we have overcome the traditional limitations associated with the configuration.
Two stroke opposed piston compression-ignition engines have a number of advantages, including low vibration, the avoidance of a heavy, high thermal mass cylinder heads, the avoidance of valve gear, and the ability to perform very complete linear scavenging of exhaust gases prior to compression by clean air for the next power cycle. These benefits are recognised in a number of engine research and development projects that are ongoing around the world today.
This remainder of this section provides, for those that are interested, a view of some historical axial and opposed piston engines.
The axial-type axial engine comprises a series of parallel cylinders wrapped around a drive-shaft, with the pistons coupled to it through either a....
or a cam ---
or a wobble-plate ---
As the pistons are driven back and forth the swash-plate, cam or wobble-plate is driven round and is coupled via the drive shaft to the load.
One such engine, the Statax, is believed to have powered an aircraft in 1914, whilst another, the seven-cylinder Redrup Fury, known to have flown in 1929, is shown below with part of the casing cut away to show the swash-plate linkage.
The Fury was one of a whole series of engines designed by Charles Redrup whose story is told in Diesel Publishing book, "The Knife and Fork Man". He always claimed that most of his prototypes were made in his home workshop with little more than a knife and fork!
A recent engine project based on the cam principle, was known as the Dyna-Cam, a double-ended spark-ignition barrel engine with twelve cylinders arranged on either side of one cam:-
Opposed Piston Engines
During the 1920's the German company Junkers developed an unusual engine with two opposed pistons in each cylinder:-
The Jumo Engine
The two sets of opposed pistons drove two crankshafts, linked together by a train of gears to the drive shaft. The engine was a two-stroke diesel, and used ports at each end of the cylinder liner for inlet and exhaust. Such engines were produced under licence by Napier during the 1930's.
A modern two-cylinder version of this engine is manufactured by Weslake Air Services Limited.