Please Critique this motor design

Doesn't look good to me...huge side force on those blck sliding vanes which are conveniently un-named....

Rather than rotating the weird cam shaped thingy ...the ignition will jam/bend depoist combustion products on those bad black slideythings.

No sardines in the design either ... that sucks....

Del

I guess I'm hijacked the students thread & asked the real question(s). I always like to shine some light on all the latest generators, the problem is all they seem to generate is hot air [which seem to have an earthy smell]

I'll throw in a couple of bonus question/answer

LOL!

Those pictures reminded me of a test on electrical symbols in a CAD course I took in high school. One of the guys in the class wrote "robots in disguise" to define the transformer symbol lol.

1. I agree with Del - since the ends of the black vanes have to seal with a surface at a constantly changing angle, they must have rounded ends, which means a single line or curve of contact, which will wear quickly.

2. The expanding gases are never able to push in the direction of rotation, since the vanes do not rotate. The cosine of 75 or 80 degrees (the angle between the direction of expansion and the direction of motion) means very inefficient transfer of energy from the expanding gases to the rotating parts.

Interesting concept, but I suspect even less durable than a Wankel.

Dick

I also agree with Dell as well as with you, Dick.

Initially, the shaped side walls were stationary and the rotor in the middle was turning. In this case the 'black' vanes have centrifugal forces against the outer wall that needs to be addressed. But this way, the inlet and outlet ports are stationary.

Having it reversed, a stationary center section and rotating side cams means that the inlet and outlet port also have to 'rotate', or they need a sliding contact somewhere. Not a good technical solution.

The key mechanical difficulty is the variable angle contact during rotation and over the width of the contact radius of the vanes. This causes sealing and wear problems likely worse than that of the Wankel engine. The angle at the Wankel engine is at least constant across its contact length. Who knows, the seal contact may vibrate having only a frail support from the thin extending vanes.

Also, only one seal member can never seal as well as several piston rings in an RPE that have area contact. High pressure can not be contained. Lubrication of the seals is another concern.

It has all the difficulties of an axial sliding vane machine. No way around it. Friction, lubrication and wear are issues to be solved.

The key thermal difficulty is a large surface area compared to displacement volume and a very poor combustion chamber shape, initially divided into two pockets. The combustion gases must be transferred from the compression side to the expansion side during a very short time through a very small cross-section also adding to thermal losses.

Most likely, this design does not allow Diesel operation, thereby eliminating it from many applications.

I trust that the Wankel engine is the better choice in comparison. Considering that the Wankel is also very limited in its use, I really do not see much hope for this one. If it ever works its fields of operation are likely very limited.

The Wankel has a comparable ratio of stroke to piston diameter of .33 (RX7/8). F1 engines near 0.4 and large ships Diesel near 2.6. The larger the stroke the larger the efficiency.

I think this design is similarly small in S/D ratio than that of the Wankel engines and it can not be freely changed. Consequently it will have very low fuel efficiency, is my guess. High speed operation may be a problem as well. Remember we have two key engine characteristics. One, fuel consumption in g/kWh and two, engine weight per engine power. In both it likely can not compete with the RPE. For high efficiency you need a compact combustion chamber shape and long stroke, for low weight you need high speed capacity. It has neither, it looks to me.

Generally it is like this, if the overall concept seems very simple, the technical difficulties are then in the detail. You cannot trick nature to be simple in all aspects.

Floram

'the inlet and outlet port also have to 'rotate', or they need a sliding contact somewhere.'

Timing could provide the answer.

'the variable angle contact during rotation and over the width of the contact radius of the vanes. the seal contact may vibrate having only a frail support from the thin extending vanes.only one seal member can never seal as well as several piston rings in an RPE '

I like this design, I think this is only a depiction and depending upon surface conditions various non-conventional seal types could be employed. Piston rings are not considered seals and they are designed to blow by hence the PCV.

'The combustion gases must be transferred from the compression side to the expansion side during a very short time through a very small cross-section also adding to thermal losses.'

A timing issue and thermal losses are beneficial generally.

'this design does not allow Diesel operation, thereby eliminating it from many applications.'

In what way?

'low weight you need high speed capacity.'

You spoke the thought in reverse? I do that too.

It was not steam that caused power in the original steam engine but the vacuum...

Piston rings are not considered seals and they are designed to blow by hence the PCV.

I wonder what pistons are if they are not seals. What is their function then? Why do we need them at all, it not for sealing?

In my opinion they are damn good seals, and they still can not seal 100% and allow a fair blow-by. Imagine the blow-by that will occur with these single vane seals of only one angular changing line contact at any one time and extending out a long distance on a thin blade with no lateral support.

As a side note, very high air pressure pumps or compressors use up to 10 piston rings in series. Only this way several 100 bar pressure can be achieved. A single piston ring could never do that, and a single seal with only a curved line contact even less so.

Your other responses fall in the same philosophy of thinking, in my opinion. Nevertheless. I wish you good success with that design. Do you have any performance data you can report on? I would be interested to see results.

There seems to be a lot of confusion about piston rings.

Obviously they do not seal 100%. But they are designed to seals.

Gas pressure presses the ring down against the bottom land, it also gets 'behind' the ring and forces it outwards. Many people think it's the springiness of the ring which provides the sea, I belive it is the gas pressure acting outwards.

Maybe my memory is wrong on this.... but that's what I recon...maybe this needs a thread/question on its own?

Del

You got it right Del,

Move the piston slowly, the rings

An o-ring or lip works the same way, the pressure improves the seal.

I am also curious that a prototype has existed since 2003 and we do not see a video of the tests.

Furthermore the improvements "since the prototype" gravitate around improved sealing, avoiding leakage etc.

It confirms they encountered the problems you envision in your remarks.

"I agree with Del - since the ends of the black vanes have to seal with a surface at a constantly changing angle, they must have rounded ends, which means a single line or curve of contact, which will wear quickly."

I suspect the depiction is just that and not actual.

'The expanding gases are never able to push in the direction of rotation, since the vanes do not rotate. The cosine of 75 or 80 degrees (the angle between the direction of expansion and the direction of motion) means very inefficient transfer of energy from the expanding gases to the rotating parts.'

All of the engines I have built for performance have had an optimal timing of several degrees BTC. Yes firing occurs before the piston reaches its zenith, compression precipitating power. Until pollution standards polluted the factors of performance.

side note: my 1965 Impala with 283 cu conventionally aspirated engine weighing near twice current models used less fuel ??? If less goes in...

I forgot to link to the discussion that caused me to start this thread

http://cr4.globalspec.com/thread/17799#newcomments

Followed up on your link, where I found another link, I had to give it away as I felt I'd end up going round in circles, I find rotatory engine ideas fascinating, something I tried to create where I was younger, so its interesting to see others ideas. I think it would probably work, but I think the world is moving away from such concepts? Dont mean to stray, but watched an interesting TV programme the other night, who murded the electric car? (EV1).

Regards JD.

Sorry bout that,

California air resources board

mandated 4% ZEV [zero emission vehicles] for 2004, as the deadline got closer GM Honda & Toyota went through the motions & threw some stuff out there to "test The market"

as soon as CARB buckled & the mandate was recinded, all the electric cars headed for the shreader.

So I would say CARB both created & killed the electric car.

I never really believed that oil companies and such would go out of their way to kill a project, but to keep faith one has to think that there was more to it? Back to rotary engines, I have spend quite a few hours thumbing thought old patents, and they can be quite interesting. The first Wankel was designed like a centrifugal pump, a three pointed piston and a four pointed piston. But if you think of the EV1, them I don't hold out much hope for anything new? I would like to be wrong.

Regards JD.

If you ran a car company would you want to produce a car that was less complex, cheaper & lasted longer? The shareholders would have your head. When the EV1 came out gas was cheap & SUV's were @ the peak of popularity. Toyota has sold bunches of hybreds that are more efficent, more complex & more expensive.... The shareholders are in heaven. As the price of oil continues to climb & batteries continue to improve, the straight electrics will be back.

Machining and sealing could fun but developing torque for diesel operation will negate the HP/LB ratio advertised.

This could work well on a hydrofoil design I'm thinking on...

Interesting the type applications this type design could be employed such as low rpm high torque applications may relive many of the supposed restrictions that have been stated.

So it is afterall a vaned pump and the type are popular too.

Interesting.