A three cylinder Atkinson cycle engine

Having finished the Saunderson and Mills I decided to have a go at a three cylinder Atkinson engine just for fun - it's not a scale model as it was designed by yours truly. It has a bore of 28 mm and induction stroke of just under 18mm and an expansion stroke of just under 40mm. This gives the three cylinder unit capacities of 34 and74 cc. I have fitted automatic inlet valves and side exhaust valves and it has a water pump and governor. The carby is from an old wiper snipper (strimmer in your language). As this type of engine is now used in some small modern cars I am not sure which capacity they use when describing the engine. I hope to have the engine running in the next couple of weeks and can't wait to hear what sort of sound it makes !

George.

You got that one done quickly George, look forward to the video.

Thanks for posting, J

Atkinson Cycle engines are in wide use in production cars, mainly for hybrid vehicle use (eg the Toyota / Lexus hybrids and others from Ford, Merc etc), including the original Toyota Pious.

The BMW VANOS system almost does the same thing and requires very little throttle control to control the inlet charge, instead using valve timing to do much of the work. It's the std arrangement for most of the BMW gasoline engine range now.

The car engines use variable inlet valve timing to control the inlet charge whereas the original Atkinson cycle engines had variable displacement and even opposed cylinders.

What is yours? Variable displacement? Sounds interesting!

Murray

Good Day Murray,

The engine has variable displacement with different capacities for induction and expansion. I have made a single cylinder edition of this type of engine and it's great for displays as there is plenty to look at when it's working and most people haven't seen this type of engine before. What really gets them is when you tell them that the system was design in the 1880s and the designer didn't have a computer!

George.

A great engine and something to be proud of.

I like the flywheel, is it from a casting ? I'm interested mainly in steam engines but would love to be able to make wheels like that, at the moment with limited experience and tooling I struggle to make an attractive looking wheel.

Good Day Peter,

The flywheel is the one casting I didn't make. I think it may have been a shell mould casting. It was given to me many years ago in return for a job I did for some one. It's a great casting in bronze and I have been waiting for the "right" job to use it on. I am hoping that this engine will run at steam engine speeds (quite low) as that will enable the action to be seen. Thanks for the comments.

George.

Thanks George, its a great little engine and the wheel suits its style nicely.

I look forward to hopefully seeing it running