I’ve been following a series of videos on YouTube of a couple of guys who have been busy building a Briggs and Stratton engine with a transparent cylinder head. They’ve now got it running surprisingly well:
This is a pretty interesting concept – very similar to a ‘split cycle’ engine – basically the rotary version. A split cycle engine has the benefit of being able to split the compression and expansion cycles of a traditional internal combustion engine. This allows for different geometries in the combustion and expansion chamber, allowing for things such as very high expansion ratios verses compression ratios, and also potentially volume combustion in the case of this particular engine.
It looks as though this engine would still suffer some of the difficulties of traditional rotary engines, but still a very interesting concept!
So a friend told me about the Duke Axial Engine the other day. It’s certainly a very interested idea and does produce some clever solutions to some of the fundamental complexities and disadvantages to the reciprocating internal combustion engine. I always like the idea of novel engine designs, and this one certainly looks like it has potential. Take a look at the video followed by some analysis after the break.
I’ve made a video of the whole system explaining all of the sensors, actuators and interfaces, and some of the more advanced indicating equipment that I’m using.
A more detailed explanation of the closed loop ignition timing control is given here: http://scottsnowden.co.uk/?p=341
I have been busy over the last few weeks with various things, but have now completed most of the practical work on my project and am now at the stage of writing up the report/dissertation. I have successfully managed to achieve closed loop ignition timing control by using the Stellaris Launchpad development board to directly interface with the optical encoder on the engine and the pressure sensor charge amplifier (this replaces the AVL IndiSet 620 in my system).
Honda New Zealand have a really nice explanation of their ‘Variable Cylinder Management’ technology. The idea behind this is similar to the Scalzo Piston Deactivation Engine in that it reduces pumping losses in the engine at part load. The great thing about Honda’s system is that it utilises the already proven VTEC technology to achieve a similar effect. The disadvantage compared with the Scalzo engine is that it cannot remove the friction losses as the pistons are still connected to the crank shaft and still move up and down in the bore. The Honda v6 engine can run on 6, 4 or 3 cylinders.
Some engines can ‘deactivate’ cylinders by preventing the valves from actuating, and hence inhibiting any airflow through that cylinder. This is great for part load conditions, as it reduces some of the pumping losses of the engine. This system doesn’t quite achieve full cylinder deactivation though, as the piston still moves up and down in the cylinder, hence some energy is still lost to friction. The Scalzo ‘Piston Deactivation Engine’, however, can deactivate the whole cylinder and stop the piston from moving. Continue reading