New Engine Design: Doyle Rotary

[ADoyle88]

I'm posting here to hopefully get questions, comments, suggestions and criticisms. My dad has been developing a new engine for 25 years and now has a design (patent pending) that is ready to be released to the internet.

His design is a split-cycle rotary-piston engine that utilizes proven materials and parts in new configurations. The engine has two rows of cylinders rotating around a stationery crankshaft. The pistons are aimed inward toward the crankshaft. One row of cylinders is responsible for intake and compression while the other bank of cylinders is for power and exhaust. The intake port, central combustion chamber and exhaust port run through the crankshaft. The central combustion chamber links the two rows of cylinders together and contains a fuel injector and spark plug.

Describing the engine is difficult but the following video should help:


More information can be found at doylerotary.com

Thanks for any comments,

Adam Doyle

 

[BryGuy]

Its very interesting. I bet it would crazy to watch. Basically an inside-out Le Rhône.

To be honest though I don't see any advantages over a direct injected over-head cam diesel.

 

[ADoyle88]

The Doyle Rotary does not have a valve-train. So no energy is lost to turning the camshaft to open the valves. Instead of valves, ports are opened to the cylinders as the motor turns over. These ports open and close instantly rather than gradually opening and gradually closing like in a conventional engine. This increase the duration of wide open flow from the ports.

Our motor should have a higher fluid efficiency because the flow into and out of the motor is never interrupted. In a conventional engine air rushes through the intake while the intake valve is open. When the valve closes the air passage is abruptly closed and causes a pressure wave to bounce back up the intake, increasing turbulence in the runner. In our motor there are always two or more pistons pulling air in. The air passage is never blocked and flows continuously. The same holds true for the exhaust port.

It is interesting that you compared our motor to the Le Rhône. Many people have commented to us that our motor should not be considered a rotary motor because it is unlike "the rotary motor" (Wankel) because our's has pistons. But as you pointed out, our's has much in common with the original rotary motors (Gnome and Le Rhône). This is why we consider our's to be a rotary motor.

Thanks for the comments.

 

[ADoyle88]

I have posted a video that should help explain how the Mazda seals are used in our engine.


These Mazda seals lead us to a possible disadvantage of the motor. In the Wankel, oil injectors add oil in front of the seals to preserve the apex seals. Because this oil is injected into the combustion chamber, small amounts of oil are burned during normal operation. Burning oil not only increases negative emissions, it also increases running costs slightly (replacing the oil periodically). The Wankel has successfully passed emissions standards which shows that the amount of oil burned is relatively low. The emissions issues may not be as big of a factor for our motor though. This is because our seals are not required to follow a complicated irregular path. They slide against a perfectly round sealing surface. The seals in our motor should require less spring pressure to seal against the circular. Decreasing the pressure will lower the amount of friction on the seal and also lower the amount of oil needed to preserve the seal. So the negative emissions could be significantly lower than the Wankel.

If any questions remain, feel free to ask.

 

[Paul S]

Thank you for sharing. This is really out of my field but it looks interesting.

Unfortunately all I really remember from the combustion engine course I once took (besides going to the junk yard to find parts) are the thermodynamic cycle P-V diagrams. Can you share a P-V diagram for this cycle and how does it compare to other typical engine cycles?

I quickly looked at your website and have two more questions.

The current prototype, how does the size of your engine compare to an equivalent in power, typical engine?

I see that some of the aluminum that is used in your engine is 6061. I don't know what aluminum is typically used in engines but I do work with aluminum structurally and I know that prolonged high temperatures (+500 deg F) will weaken the strength of this alloy. Is this a concern and if it is, how have you addressed any heat issues?

 

[ADoyle88]

We have attempted to perform P-V diagrams but I am only a student and my dad is a machinist and the calculations are a bit out of our league. Also, calculating the volume isn't as easy as a conventional engine; in our engine multiple cylinders are open to one another at various times. Some high dollar CFD software could make quick work of it though. Months ago we wrote a check for $20,000 and drove hundreds of miles to an appointment with an engineer at SouthWest Research Institute in San Antonio hoping to hire a team of thermodynamics experts to study the engine and calculate the P-V information for us. However the experience was not a good one. The engineer obviously did not really want to learn the engine and got a glazed, day-dreamy look in his eyes as my dad described the engine to him. At the end of it all (verbal descriptions accompanied by 3D models and animations) it was obvious the engineer still did not understand and we decided to save our money and time for someone else.

The current prototype seized up very quickly after firing. We had built the prototype out of materials we had around (my dad machines aircraft parts...this is the reason we used 6061) assuming that the Mazda seals would survive at least a little while sliding against an aluminum surface. But the seals quickly dug into the aluminum and the engine locked completely up. To remedy this, we will be building the next prototype using the standards that are used for the sealing surfaces in the Wankel engine (chrome plated and treated to the correct hardness). Because the engine instantly locked up we could not get any power information.

We can make some general guesses to the power output by comparing our engine to a conventional engine. Assuming that our engine has the same efficiency and power output per CC, our motor would be better because of its size and weight (we believe it will actually be more efficient per CC due to several advantages our design has over the conventional engine...you can find a list, with explanations, of these advantages on the website or I can post them here, just let me know).

We consider the size and mass of our motor to be a great advancement over the conventional engine. Our engine is 11.5 inches long and 18 inches in diameter with a working displacement of 4181 cc (~255 ci). When a bounding box is placed around our engine and around a small block chevy with a comparable displacement we find that our engine contains 1.5cc of displacement for every cubic inch of physical space while the small block chevy only contains .47cc per cubic inch of space. Our engine is more compact.

As for the mass, fully assembled the Doyle Rotary comes to 220.5 lbs. A 350 small block chevy weighs 685 lbs (http://www.enginefactory.com/chevdimensions.htm). You can see our engine is .86 lbs/CI while the chevy is 1.95 lbs/CI. Also concerning mass, the total rotating mass of our motor is 68 lbs while the total rotating mass of the chevy (crank:54, flywheel:35, and crank end of the rods:8) comes to 97 lbs. We might have to actually add weight to the rotating mass to increase the angular momentum.

We do not have data with which to make claims of expected power output and will not post fictitious numbers. We are trying hard to not be like the hundreds of others inventors spamming the internet with made up data. We know that hard data will be achieved only after we build and test the next prototype (we hope to start machining parts in two weeks but do not expect the prototype to be finished for a long while because we are funding the project ourselves).

Thanks for the questions. We really enjoy hearing the point of view of people not near to the motor.

 

[EnvEngineer]

Can you provide a better step by step discussion of the process, from what I can get from the video and web site is that all cylinders go through the intake - compression - ignition is in a seperate chamber - and then power is transmitted back to the cylinders? Is this correct.

You have not discussed lubrication and cooling, the volume of a small block chevy is such to circulate water for cooling and oil where the power generation portion of the engine is small.

 

[ADoyle88]

We just got back into town from vacation. Sorry for the delayed response.

I am currently working on making an animation that shows the entire assembly and the path of the fuel and air through the motor. This video will be the best way to explain how the motor works. The progress on the animation is slow because I am new to animations and my computer struggles with so many moving parts in SolidWorks.

I can clarify the Doyle Cycle in words here though.

There are two banks of cylinders: one row is for intake and compression (IC form now on) and the other is for power and exhaust (PE). For simplicity I will pretend that the motor has one piston on the IC side and one piston on the PE side. The Doyle Cycle begins with the IC piston at TDC. As the motor turns and the piston moves toward BDC air is pulled into the cylinder (the air travels through an intake port that is in the crankshaft). The intake port is positioned so that when the IC piston reaches BDC, the port closes to the cylinder. Now the piston begins to compress the air. As the piston approaches TDC, a port opens to the combustion chamber. The compressed air in the cylinder is emptied into the combustion chamber and then the IC piston continues around to begin the cycle again.

When the compressed air enters the combustion chamber a fuel injector injects the appropriate amount of fuel and a spark plug ignites the air-fuel mixture. The air-fuel mixture is allowed to burn a for a very short duration and then the pressure is released to the PE cylinder. At this point the PE piston is just past TDC. The pressure from the burning fuel forces the piston out (this is where the torque of the motor is achieved). When the PE piston reaches BDC, the power port ends and the exhaust port begins. The PE piston pushes the exhaust gases out of the engine on its upward stroke. At TDC it begins its cycle again.

I hope that this has helped. Hopefully by the end of this week I will have a final animation.