The covaxe® engine

covaxe® combines the axial and opposed piston engine architectures and applies new patented concepts to them to produce an exceptionally efficient, well-balanced lightweight engine with inherently low emissions for a wide range of applications.

The animations show that the engine features opposed pistons acting on shaped cams through rollers.

The use of shaped drive cams enables the motion of each piston to be determined independently, unlike a crank-driven engine, in which the piston motion is constrained to be virtually sinusoidal, and so the covaxe® combustion cycle can be optimised.

The complete cycle occurs twice for each revolution of the drive shaft.

Thermal Efficiency

covaxe® uses the ability to design cam profiles flexibly, to optimise the thermal efficiency of the two-stroke compression-ignition engine.

With a conventional crank-driven compression-ignition engine the injection of fuel continues during the power stroke as the pistons move down the bore, or, in the case of an opposed-piston engine, as the pistons move apart.

Thus full combustion pressure is not generated at Top Dead Centre.

With the covaxe® engine, the cams are profiled so as to maintain a constant combustion volume until fuel injection and combustion are complete, so that full combustion pressure and temperature are available to drive the pistons along the cylinders, thus maximising thermal efficiency. The covaxe cycle combines the thermal efficiency advantages of a spark-ignition (gasoline) cycle and a compression-ignition (diesel) cycle.The combustion regime thereby reduces CO2 emissions and is tailored to reduce significantly particulate emissions.

The illustration shows a four-cylinder engine although our current baseline engine has seven cylinders.


The use of the opposed-piston arrangement within the covaxe® engine ensures that the forces within are balanced to produce a quiet engine with exceptionally low vibration and an even torque delivery without the need for a large heavy flywheel.

Simplicity and Maintainability

In addition to the significant particulate emissions reduction, a striking feature of the cylindrical profile engine is the mechanical simplicity, with far fewer parts than an equivalent engine. Furthermore, the axial combustion forces are carried by the central shaft enabling a lightweight casing. We believe that the engine will therefore be very competitive in terms of price and weight per unit power output.

covaxe® employs a patented modular cylinder assembly approach which enables ready access to main components for maintenance purposes, without having to totally dismantle the engine. The engine is made in modular form for ease of manufacture and assembly.

The Engine


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