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Free piston internal combustion engine

Free Piston Internal Combustion Engine

Quote Ref: KT120496-W

The Challenge

Traditional small internal combustion engine systems have many drawbacks including limited operational optimisation possibilities, low efficiency and low power-to-weight ratio.

Previous free-piston engine developments have been designed with 2-stroke ‘ported-valve’ arrangements, and therefore suffered from poor fuel efficiency and high exhaust gas emissions. Another challenge for previous free-piston engine developments is related to piston motion control.

The Solution

A novel free-piston internal combustion engine is being developed by researchers at Newcastle University. This novel system uses a two-stroke ‘crank-less’ petrol engine system with the capability of running in a four-stroke arrangement (i.e. with independently activated overhead inlet and exhaust valves). This allows the system to run in a ‘spilt-cycle’ mode, achieving air-fuel intake, compression, ignition, power stroke, and exhaust within the two piston strokes.

This novel configuration provides higher fuel efficiencies and lower gas emissions when compared to ported valve free-piston systems, while maintaining the significant benefits of free-piston engines over traditional crankshaft systems, such as compact design, low friction, higher efficiency, high controllability and high operational flexibility.

Electrical power generation is via a linear electric generator which incorporates encoder position control, and the ability to act as a motor in the system starting mode. The system includes electronic control based on piston motion, which optimises valve, fuel-injection, and ignition timing. This high level of operational control allows dynamic variation in the compression ratio, providing optimised running conditions and flexibility for different fuels, as well as improved control over exhaust gas emissions. Even greater fuel efficiency and emission reduction can be achieved through the use of homogeneous charge compression ignition (HCCI) and this will be the next step in the system development. The development is also linked to another external combustion free piston engine system for micro-CHP with high electrical and overall efficiency.

The Opportunity

First proof of concept prototypes have been developed and a second generation prototype was completed in early 2013. We are now looking for potential investment and commercial collaborators/partners to assist taking the proof of concept closer to commercialisation. It is envisaged that this new system would provide vehicle engine manufactures with a more efficient engine system with a particular focus on hybrid electric or range-extended electric vehicle applications.

Other applications include CHP (combined heat and power) since the electrical efficiency will be considerably higher than current IC-CHP models on the market and portable power applications. The system can be adapted to different fuels such as diesel, bio-diesel, bio-gas, or natural gas.

Intellectual Property

The technology is protected on a concept level through patent applications currently being prosecuted at a PCT and UK level. Patentability has been indicated for the basic split-cycle free-piston engine concept, as well as the same concept adapted for HCCI operation. (Application accepted for grant by the UK Patent Office.)

Title: Free-piston internal combustion engine
PCT publication no. WO2011144926
UK patent application no. GB1008319.4

Other related patent applications
Title: Heat Engine (micro CHP)
Europe: patent application no. 10714669.8
United States: patent application no. 13/263,153
China: patent application no. 201080015873.X

Title: Combustion ignition free-piston internal combustion (HCCI)
UK: patent application no. GB1120106.8 (app date: 22 Nov 2011)


Dr Jayshree Johnstone, Science, Agriculture & Engineering Enterprise Team, Research and Enterprise Services, Devonshire Building, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK