Simplified Mechanics

[Lonny Doyle]

Fox,

I think very highly of The Doyle Rotary Engine also.

What potential problems do you see with it?

[fox]

Hi Lonny,

Well, I wished I would have fully understand the Doyle engine principal of operation (which I don't).

A pressure vs both piston dynamic volumes (one set ) plot would have helped much.

[Lonny Doyle]

Fox,

We have a University that has it's aerodynamics lab doing independent research on the Doyle Rotary. They are creating models to simulate both the conventional four stroke and the Doyle Rotary so they can overlay them. Good or bad this will illustrate, using graphs and numerical data, how the efficiency numbers of the DRE compare to the conventional four stroke.

When they finish their analysis I will post their information.

I hope it is great news or I will be back to the drawing board.

Lonny

[MHamil]

Hey Lonny, 

I hope it is good news too.... Any estimate on when the study should be done? 

Cheers, 
MHamil

Aug 31, 2013 15:20:21 GMT Lonny Doyle said:

Fox,

We have a University that has it's aerodynamics lab doing independent research on the Doyle Rotary. They are creating models to simulate both the conventional four stroke and the Doyle Rotary so they can overlay them. Good or bad this will illustrate, using graphs and numerical data, how the efficiency numbers of the DRE compare to the conventional four stroke.

When they finish their analysis I will post their information.

I hope it is great news or I will be back to the drawing board.

Lonny

[Lonny Doyle]

MHamil,

The study is suppose to be complete by the end of September.

[Sally]

Wow Lonny, I hope the University publishes a really positive finding with the DRE. Any chance you will share it with all of us?

[Lonny Doyle]

Only if it is good! LOL

Good or bad I will upload it too our website and then post a link on here.

[fox]

Hallo Lonny,

OK,I will stay patient and wait , Here is one more question:

I believe that the exact switching points (initial open and initial close) of the cylinders ports (compression and expansion) are crucial for success.

The compression cylinder closing point (probably) is close to its TDC, what's the range the port stays open ?
The power cylinder initial opening point (probably) is close to its TDC, whats the range it stays open ?
Having the requested information may help me in understanding the thermodynamic nature (will try to draw an imaginary PV plot.
Enjoy your weekend

[fox]

Lonny, In regard to the above question, The question relates to the passages between the combustion chamber and the cylinders (not related to intake and exhaust strokes, only for the compressed gas transfer flux)

[Lonny Doyle]

Fox,

It is easier to visualize the Doyle Cycle on a twin cylinder conventional engine.

The first cylinder is Intake and compression, it has a conventional intake valve and also a valve that opens to a combustion chamber that is located between the two cylinders.

The second cylinder is power and exhaust, it has a valve that opens the combustion chamber to the power stroke and a conventional exhaust valve.

The power and exhaust piston reaches TDC around 60 degrees after the intake and compression piston. This gives the engine plenty of time for combustion.

I will start with the power stroke.

The combustion chamber first opens to the power stroke while the piston is at TDC. Since there is very little space above the piston combustion flow is minimal.

As the power piston moves away from TDC the area above the piston continues to be filled with pressure from the combustion chamber. Around half the way through the power stroke, when the crank angle has reached its best leverage we close off the combustion chamber.

The pressure in the power cylinder continues to push the piston toward BDC. If we time this correctly when the piston reaches BDC the cylinder pressure should be near zero having used all of the available energy.

The rest of the energy from combustion was stored in the combustion chamber to be used on the next cycle. Normally, in a conventional four stroke, the left over pressure is exhausted on every cycle.

During our compression stroke we compress until the compression pressure is slightly higher than the stored pressure in the combustion chamber. This is so when we open the compression cylinder to the combustion chamber it does not try to back up. From our calculation it needs to open around 70 degrees before TDC.

If we keep the power stroke open longer we can open the compression sooner.

If we run a larger expansion piston it also changes the timing.

We have created spread sheets that allow us to change the timing events and see how they interact with each other to get a rough timing for my prototypes. The simulation that the University is working on will include combustion, this will help us get closer to the optimal timing much quicker.

The following animation might help with understanding the Doyle Cycle.

www.youtube.com/watch?v=MMqYJoJaDAo&list=TLukWz9-wAPhtxEerBb48ayMfRFavrnTsb

[fox]

Hi lonny,

Thanks for the detailed "go through" explanation. It will take some time for me to conceive.
Just one more clarification, if I got it right the engine has a single combustion chamber which alternately serves every 60 degree another pair of cylinders i.e. one power cylinder and one compression cylinder while there might be some phase angle between both radial locations (still keeps 60 degrees between the six power cylinders and 60 degrees between the compression cylinders?)

[Lonny Doyle]

That is how our old design was setup but we have actually changed things from that design.

We have made each pair of cylinders independent of each other. This allows us better control of the compression ratio.

It is easier to understand the Doyle cycle using a conventional engine layout.

Just think of a pair of cylinders, one is for intake and compression and the other is for power and exhaust. They are joined to each other by a combustion chamber.

We compress air and fuel into the combustion chamber and ignite it at TDC after the valve closes. We have combustion for about 60 degrees then the power and exhaust piston reaches TDC. We then open the combustion chamber to the power and exhaust piston, this gives us our power stroke.

[fox]

In my opinion, those are good news for Lonny (separate combustion cells for each pair)! Got the idea, appreciate your patient.
In the mean time, years ago I spent some time working for a company that built a rotary split cycle engine.
Here is its principal of operation.

www.youtube.com/watch?v=tZ2gFcD4bkE

[Lonny Doyle]

Fox,

I was curious as to what kind of seals they used.

I would think it must have been quite the challenge to seal.

It definitely has very few moving parts.

I wonder where they are today with their idea.

[fox]

Lonny,

They use multiple gray iron (cast) seals,

The sealing were bad.

In regard to moving parts, well, both abutments dynamically followed the rotor shape by utilizing gears, cranks and connecting roads. So ..... quite more then few parts.

For fogy (sorry, I don't have a better one) impression, please watch :

youtu.be/jcWtiEGXx4M

The idea was abandoned.