"Hybrid Synergy Drive" minus the electricity..

[shovel]

Toyota's hybrid system uses an atkinson cycle engine mated to an electric motor through a variable transmission..

But what if this idea was combined with the idea of variable displacement engines? For example a two cylinder atkinson cycle engine which runs accessories (alternator and such), mated to a two cylinder otto cycle engine through a CVT so that the system as a whole performs effectively as a variable displacement engine - the otto cycle engine could shut off entirely when torque isn't needed, and get "bump started" by the continuously running atkinson engine whenever its power is required.

The advantage I see over current cylinder deactivation schemes, would be that dormant pistons wouldn't need to be in motion (or at least, moving as fast) when active pistons are operating - and continuous load accessories like AC and electrical could be operated by a more easily optimized atkinson cycle ICE.

So.. that's my thought - I don't have the means to bring it into reality, but I welcome discussion.

[Fat Charlie]

You'd want a common cooling system to keep both engines up to temperature, and you'd probably want a common oiling system for the same reason. At this stage it looks like you'd be adding needless complexity, but once it's implemented smoothly it could work really well.

[UFO]

Why an otto cycle? Isn't the atkinson cycle more efficient?