Free-Piston experimental engine returns to Lincoln:Engineering labs

Free-Piston engine cambelt drive transfer box

After a successful meeting with Lotus Powertrain and a representative from Toyota Research Laboratories, I loaded the van up with the free piston engine, and brought it back to Lincoln, where it will be installed in one of the experimental test cells when we move into the new building.

The next stage in the development will be for Control Techniques to recommission the electrical drive and position controller for the rotary machine.

The free-piston engine in the laboratory ready for re-commissioning

This engine is absolutely unique, as it is able to function as a conventional single cylinder research engine, or as a free-piston engine by disconnecting the connecting rod from the crankshaft.

Presently the engine is set up in conventional operating mode, as a single cylinder research engine. It is novel in this operating mode, as the crankshaft is connected to a low inertia, high torque electrical servo-motor, which allows us to not only apply dynamic loads to the engine, but also control the shape and phase of piston trajectories, particularly through top-dead-centre.

This has allowed us to achieve the first dynamic examination of Quasi-Constant-Volume-Combustion, by reducing the piston velocity through the combustion phase of the cycle through top-dead-centre. This activity resulted in the paper

Chen, Rui and Winward, Edward and Stewart, Paul and Taylor, Ben and Gladwin, Dan (2009) Quasi-constant volume (QCV) spark ignition combustion. In: 2009 SAE World Congress, 20-23 April, 2009, Cobo Centre, Detroit, MI, USA.

The next research steps over the forthcoming year will be the investigation of the thermodynamic cycle using advanced control techniques, none of which are achievable on any currently produced engine configurations. We will be reporting on the research outputs in due course.

Prof Stewart at Lotus Headquarters in Hethel, hoping they'll let him take the Evora around the test track

Many thanks must go to the Lotus team for fitting the new linear motor/generator which we designed and built. In particular to Jim Young, who has been responsible for most of the modifications to this engine, which have been in many cases outlandish and seemingly impossible. Well done Jim!

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