True Rotary Vane Engine

[Rufe0]

Hello

Just throwing around some ideas and thought of this, don't think I've seen anything like this before.
The idea is a true rotary vane engine, just like a normal rotary vane pump. If you google rotary vane engine you get MYT engine or swing piston engine which aren't rotary vane engines at all.

As the rotor rotates the shape of the casing compresses or expands the area between the rotor, vanes and casing allowing for the 4 phases or strokes of an internal combustion engine. I chose to arrange this with a large power stroke, normal compression stroke and very short exhaust & intake strokes. It would work the same with equal length strokes.

It's only a basic mock up that would need alot of tweaking but I figure it's a reasonable design considering the tried and tested nature of the good old rotary vane pump.

https://drive.google.com/file/d/0B3mb0a3lQeWNTGRxTmhGM3FXSEE

Just encase your wondering why the extreme number of vanes I first mocked it up with lower vane count but found there would be significant leakage between the phases or strokes which can only be a bad thing surely. The above example has the minimum needed to ensure zero leakage.
https://drive.google.com/file/d/0B3mb0a3lQeWNY2cyUVJhX1F1dTA

Thoughts, comments or suggestions?

Thanks Adam

 

[Rufe0]

Equal stroke length
https://drive.google.com/file/d/0B3mb0a3lQeWNXzBGeVkweDE5NWc

 

[pkastagehand]

My grandfather had a design idea for something like this 30 or more years ago but with fewer vanes. Only 2 vanes basically; diametrically opposed.

Might run in a model in short bursts, but I don't know how you would seal all those vanes. In a long running engine (real auto/truck service) wear on seals would kill it quick I think. That was/is a problem I believe with the Mazda rotary apex seals.

Paul

 

[Rufe0]

Yeah normally a rotary vane pump is drenched in oil practically, I wonder if it would work as a diesel engine then you could use the diesel itself as a lubricant like a 2 stroke diesel.

 

[charlesfitton]

I'm not sure that leakage here would present the problems that we think...the compression side would be ( sort of ) balanced by the next compression vane area, as would the power, and this would be the case in all of the parts of the cycle...

 

[Rufe0]

I'm not sure that leakage here would present the problems that we think...the compression side would be ( sort of ) balanced by the next compression vane area, as would the power, and this would be the case in all of the parts of the cycle...

Sorry not sure I understand what you mean.

 

[Rufe0]

I'm not sure that leakage here would present the problems that we think...the compression side would be ( sort of ) balanced by the next compression vane area, as would the power, and this would be the case in all of the parts of the cycle...

Ah I think I understand what you mean, each area has to 'seal up' the pressure differential to it's neighboring areas, if you have a high vane count then it's likely your neighboring areas will have pressures close to your own. Thus the pressure differential won't be very high and not much sealing would be necessary. I had counted this effect as another plus for high vane counts.

The only problem I see with high vane counts is I believe (just a hypothesis) the rotational moment caused by the power stroke will decrease. I imagine the casing surface as a gradient and the vanes like a ball rolling down that gradient. The steeper the gradient the more the ball will want to roll. Increasing the vanes decreases the gradient.

On the other hand with more vanes you have more power strokes per revolution so would this make up for each individual one being less powerful?

And of course more vanes means more friction...

 

[Rufe0]

I found a few videos on youtube of very similar designs, I guess the sealing problems are insurmountable.

 

[tornitore45]

I may be missing a fundamental principle of physic... but assuming perfect seal I fail to see how a string of adjacent connected vessel of increasing volume holding progressively diminished pressure would generate a resultant force with a lateral component pushing on one side moving the entire string.

 

[Cogsy]

would generate a resultant force with a lateral component pushing on one side moving the entire string.

After combustion of the fuel the pressures on one side would be much higher than the compression side and there would be a net larger force in the chambers on that side. These higher pressure chambers would overcome the resistance of the lower side and rotate the assembly.

Generally, if you get large unbalanced forces then something has to move. In this case the only movement available is to revolve around its axis so that's what it would do. I have no idea how efficient it would be but I can see it actually moving.

 

[Rufe0]

I may be missing a fundamental principle of physic... but assuming perfect seal I fail to see how a string of adjacent connected vessel of increasing volume holding progressively diminished pressure would generate a resultant force with a lateral component pushing on one side moving the entire string.

The casing surrounding the rotor is curved away from the rotor so if you have a pressure volume at the point where the case and rotor are closest it will want to move to the point where the case and rotor are furthest away.

I see how it might be hard to get whats going on. It's like a cam but the case which remains stationary is the cam surface and follower which is the rotor rotates.

Also if you look at any two vanes which are adjacent, one will be slightly longer than the other and have more area, under pressure the larger vane will receive more force and so there will be a net force in that direction.

You can make a compressed air engine this way quite easily so the theory is sound, [ame]https://www.youtube.com/watch?v=olV_kzSb-IQ[/ame] it's just the engineering of using this principle in a gasoline engine. If only there was a liquid lubricant that didn't burn.

 

[Rufe0]

After combustion of the fuel the pressures on one side would be much higher than the compression side and there would be a net larger force in the chambers on that side. These higher pressure chambers would overcome the resistance of the lower side and rotate the assembly.

Generally, if you get large unbalanced forces then something has to move. In this case the only movement available is to revolve around its axis so that's what it would do. I have no idea how efficient it would be but I can see it actually moving.

I think the efficiency would be similar to a normal engine, the benefits would be that its the best of both worlds between a jet engine and an internal combustion engine.

 

[tornitore45]

RufeO & Cogsy I realized this morning in the semi-awake state before getting up that the model I described is not an equivalent of the engine.
The "vessel" is not rigid, the force on the larger surface is larger, unconstrained by the reaction on the "curved roof", motion results.

I was missing an important detail.

 

[MachineTom]

The wankels could not meet emissions I believe. Oil usage was an issue , along with sales isues. But it is a proven concept.

Two cycle diesel engines do not use diesel fuel for lubrication. They are pressure lube like all automotive engines. They use supercharger for scavenging the cylinder with exhaust valves and intakes ports.

 

[barnesrickw]

Never have seen an RX7 at an auto cross that wasn't puffing a bit of smoke. Seems when you heat them up, and run them hard the rotor seals don't work as well. I could be wrong, but that's been my observation.