Two proven ideas, put together for the first time.
An opposed-piston cranktrain and a stepped-piston charge pump, in one architecture.
What it is
The OSP is a uniflow two-stroke engine. Each cylinder carries a pair of double-diameter pistons. The larger pump diameter draws in and pre-compresses charge air on the down-stroke. The up-stroke pushes that charge across into the smaller power section of the next cylinder along.
There is no cylinder head, no valvetrain and no scavenge blower.
Opposed-piston engines are already in production. Stepped-piston engines have been built in research form. Combining the two had not been done before. We have built one and run it.
What follows from it
Any one of these you will find somewhere. Having them together in one architecture is what had not been done before.
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Integral air pump
The pump piston is one piece with the power piston, so the pistons pump their own air. Scavenge air arrives from cranking speed upwards, with no blower, no gear-driven supercharger and no turbocharger lag.
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Variable compression
Compression is set by crankshaft phase angle, and can be varied with load and with fuel. It is inherent in the architecture rather than added as a mechanism.
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Three-stage compression
The pump piston with upstream charging allows three stages, which is impractical in four-stroke and in most opposed-piston engines. It is the enabler for power density and for future low-carbon fuels.
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Fuel flexibility
Heavy-fuel compression ignition, with compression set to suit the fuel it is given. The architecture stays open to other fuels rather than being fixed to one.
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Fewer parts
Substantially fewer major base-engine parts than a comparable conventional engine. Less to manufacture, less to ship and less to maintain.
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Compact package
A compact prismatic package. Fewer major parts in less space, for the same job.
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Open combustion chamber
With no cylinder head there is full access all the way round the chamber, which makes the architecture unusually flexible for combustion work.
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Better tribology
Full hydrodynamic lubrication of the pump piston skirt, less side thrust, and blowby routed back to the cylinder rather than into the sump.
Fuel flexibility is designed in, not added later.
Three-stage compression is what enables both high power density and future low-carbon fuels. Compression can be varied with load and with fuel, and the chamber is open on every side for development. The engine is a candidate for the fuels that come next, rather than a design that has to be replaced when they arrive.
There is more to this than we put on a website.
If you are an investor, an OEM, an integrator or an engineer, write to us and say what you are looking at. We will come back to you.
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