Several comments follow which you will not like. I truly hate to be discouraging to any entrepreneur, but I feel you need a serious dose of reality.
First a bit of my background so you know where I'm coming from. I'm a regional Engineer with a large power generation company. I specialize in rotating machinery vibration analysis, transformer oil analysis, machinery lube oil analysis, infrared Thermography, motor circuit condition analysis and motor current signature analysis. I have an extensive background in industrial combustion turbines and all types of electric motors.
Enough of the resume, on to the comments.
Forget the electrical input idea. What you will get is a horribly inefficient electric motor with far more complexity that any existing type of electric motor.
Why? For one reason amony many, when you push the piston down the spring will compress and push on the rotor imparting motion. The spring will absorb energy and convert it to heat for no reason what so ever. Why have a piston at all? Just have a magnet mounted in the rotor? But then you'd be pretty close to a conventional electric motor.
Well, close in some ways, but overall that's far to complex and inefficient a way to turn a rotor, especial considering the sheer simplicity of a AC induction motor with ONE moving part and no brushes or other friction components save the bearings. I could go deeper into this, but just trust me here. Electric input for this design is a bad idea.
So that brings us to the combustion or compressed gas method.
Several things to point out here.
How are you going to compress the air fuel mixture? The combustion chamber will have to contain the mixture, and it will ignite when the piston is directly underneath? How will the air fuel get into the chamber? There is no down stroke of the piston while it’s under the chamber to draw it in, so it will have to be pushed in and compressed by something else. What? Another rotor dedicated just to feeding this one?
Is the top of the piston angled like in the drawing? If so, a large portion the energy from combustion will be directed at pushing the piston into the side wall due to the angle of the piston top. If the piston top is flat, that will dramatically increase the area of the pre ignition cylinder head space, requiring a far more compressed mixture of air/fuel to give it any power at all. And how will you get any power given the constraints on available piston surface area?
The fact that it always rotates in one direction will minimize harmonics. In fact, the very act of the object spinning when a piston is compressed is itself a sort of harmonic balancer.
This statement indicates that you do not understand what harmonics are. I’m sorry to be blunt, and I’m not trying to be rude, but that’s just a fact.
By the way, I don’t think harmonics would be an issue. It could be but if it is, it’s easy to fix. I do it all the time. But the fact that you address an issue that will not likely be a problem with an inaccurate statement regarding the subject indicates that you don’t understand what forces are at work on rotating machinery.
How will you maintain a gas tight seal between the rotor and the casing wall especially during thermal expansion? Also, regarding your comments on thermal expansion:
Now, I've thought about this idea for a long time, and consider questions like "What do you do with the exhaust" and "What about thermal expansion" to be somewhat minor design and materials questions. I am not an expert in large tooling machines or material properties, although I know a few who are, and all of them say this is very workable.
“somewhat minor design and materials questions”. Another statement that tells me you’re in way over you head here, regardless of what your friends say.
You talk about simplicity. Try this. Remove the three pistons with their energy wasting springs, replace them with continuous set of chambers around the circumference of the rotor, and instead of a combustion impulse occurring only three times per rotation, have a continuous combustion or compressed gas fed to the rotor.
Now you’ve got something.
It’s called a turbine, an impulse turbine to be exact. Something that has been around for eons, and is far more efficient and powerful that what you have here. And an impulse turbine is the least efficient type of turbine to boot. But talk about simple!
But if you do manage to sell this idea to anyone, I will declare you a genius of Einstein like magnitudes. A marketing genius that is.
Seriously, before you spend any money on this, take you idea to a mechanical engineer who is NOT a friend. He’ll save you lots of money, time and possibly embarrassment.
Once again, I’m sorry for such a negative response, but I think you need it.