Pivotal Engine

[Russ Noble]

I took the morning off today to attend Southmach 2009, a local machinery expo.

I was amazed to find a revolutionary engine developed here in Christchurch which has been produced in several guises for the last few years. Quite a bit of lateral thinking has gone into this design of a high efficiency, low friction, two stroke engine. Watercooled pivotal pistons and a whole heap of other technical innovation. And apparently ideal also as a hydrogen engine as it overcomes a lot of the problems associated with that technology. Early days yet, but it seems to be a great concept for the future.

I did a search on 'pivotal engine' and found their website. High Power Density Pivotal Engine by Pivotal Engineering Ltd - Christchurch, New Zealand.

If you're interested in that sort of thing it's certainly worth a look.

 

[Randy V]

Interesting design...

I would like to see how it does in real world "long haul" testing.. The piston seals would be a key concern.
I like the pivotal design and how the leverage is increased internally. About the only thing I'm not that crazy about is the 2-cycle design of the intake system.

 

[David Sturch]

Randy,
I do not think the seals would be an issue with the amount of work that Mazda engineers did on the rotorary. You still need injected oil for lubercation also. I wondering on torque figures and efficiency. I think they are looking for a way to produce an engine that runs on hydrogen that produces a very very low carbon footprint and yet give you performance and range at a lower price over a fuel cell battery combo.
Dave

 

[Randy V]

Dave - It was my recollection of poor seals on the Mazda / Wankel rotary that made me think of why they would be short lived here..
Are you saying they finally got them sorted out?

 

[David Sturch]

Randy,
The seals have come a long way since the days of NSU and the first R100. There is no seal problem today. The engine that Russ has shown is also a very low RPM engine for a two stroke. (peak HP a 6500 RPM) They are using the Rotax twin bottom end and the oil injection with direct injection. Similar engine used in personal watercraft small compact size high horsepower. They would get a larger piston area with the pivot.
Dave

 

[Russ Noble]

As David says the seals are not a problem.

The revs depend on the application, they have a motorcycle engine that runs to 11,500 rpm and at the other end of the spectrum their bus series - hybrid generator - that has max power at 2800.

There is an interesting comparison of their 2 litre 4 chamber engine with the 3 litre Toyota V6. Same horsepower, less than half the weight and requires half the space for installation.

The big advantage in the future for this motor is the watercooled piston which in a hydrogen application makes it much more efficient and viable than anything else that is currently available.