A compact heavy-fuel engine, built in India.
Two proven ideas combined for the first time: an opposed-piston cranktrain and a stepped-piston charge pump. No cylinder head, no valvetrain, no scavenge blower.
What follows from it
Any one of these you will find somewhere. Having them together in one architecture had not been done before.
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Integral air pump
The pistons pump their own air. No blower, no supercharger, no turbocharger lag.
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Variable compression
Set by crankshaft phase angle, and can be varied with load and with fuel.
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Three-stage compression
Impractical in four-stroke and in most opposed-piston engines. The enabler for power density.
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Fuel flexibility
Heavy-fuel compression ignition, with compression set to suit the fuel it is given.
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Fewer parts
Substantially fewer major base-engine parts than a comparable conventional engine.
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Compact package
A compact prismatic package. Less engine, in less space, for the same job.
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Open combustion chamber
No cylinder head means full access all the way round it.
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Better tribology
Full hydrodynamic lubrication, less side thrust, and blowby back to the cylinder rather than the sump.
An engine that can move with the fuel supply.
Fuels will change at different speeds in different places, and nobody yet knows the order. Three stages of compression is what enables both high power density and future low-carbon fuels, so this architecture can be recalibrated around a new fuel rather than replaced when the fuel changes. That flexibility is designed in, not added on.
How it works
It is a uniflow two-stroke. Each cylinder carries a pair of double-diameter pistons. The larger pump diameter draws in and pre-compresses charge air on the down-stroke, and the up-stroke pushes that charge across into the smaller power section of the next cylinder along.
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.
Where it runs
One frozen core. The application is, in effect, a kit around it.
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Marine
Compact heavy-fuel propulsion for high-performance craft and small vessels.
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Unmanned surface
One fuel across a fleet, instead of carrying petrol alongside heavy fuel.
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Unmanned air
Heavy-fuel compression ignition for unmanned aircraft, a class where domestic supply is thin.
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Land and power
Scalable multi-cylinder variants on the same architecture. A forward roadmap, not current product.
On the public record
The architecture is protected by a granted patent family with a common priority date of 5 April 2013.
- GB 2515254 B
- US 9,790,846 B2
- EP 2981693 B1
Built in India
The engine is engineered, qualified and made here, through an Indian supply chain. That is where the substance of a domestic propulsion capability actually sits, rather than in a certificate.
There is more to this than we put on a website.
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