Atkinson Cycle in F1

[DaveKillens]

The Atkinson cycle has to be understood first, before we can try to examine it's potential applications. The entire concept behind the Atkinson cycle is to extract as much power from the power stroke as possible. The goal of the modern Atkinson cycle is to allow the pressure in the combustion chamber at the end of the power stroke to be equal to atmospheric pressure; when this occurs, all the available energy has been obtained from the combustion process.
If you take a current Formula One engine, and attempt to incorporate the Atkinson cycle into it, what happens is that the intake valve would not close until well past top dead center. Thus, some of the intake charge is blown back out the intake port. Now can someone please tell me how you can expect to extract serious power from such an engine? Remember that all the other competitors do not run with this method, and enjoy substantial levels of power over an Atkinson cycle engine.
I haven't discussed the burn times, that this is the limit of how much RPM the engine would be capable of. Heck, if you incorporated a diesel with the Atkinson cycle, I don't expect the engine to be capable of exceeding 4,000 RPM.
An alternative is to design the engine around the Atkinson cycle. Just take this, and redesign it so it can handle 19k RPM. Good luck, you'll need it.



Remember this....The Atkinson cycle is designed to provide efficiency at the expense of power

[PlatinumZealot]

Efficiency means more power out put for a given power input
So theotryicslly, the Atkinson cycle engine should be able to make more power from the same fuel input.

There might be problems getting the revs up and having similar lifespan to current engines.. but I can say I don't know exactly what they are. Maybe Harmonics or something Even a regular engine can over speed it self to destruction, so I think material selection of the different linkages is the solution. To satisfy myself i will "fool around" with a simple model in Solidworks Motion and see how it compares to a conventional model.

[DaveKillens]

Theoretically, I own a mule and a race horse. They are fed the same amount of food each day. The mule can haul a load all day. A race horse can run really fast for a short while, before it tires. Which one would you take to go racing?

[FGD]

Actually, I think what might make a true Atkinson inapplicable is the extremely short stroke of an F1 engine. To achieve the variations in stroke which the Atkinson Cycle requires, an F1 engine would have to sacrifice much of it's bore which would result in an unacceptable loss of power.

[PlatinumZealot]

Theoretically, I own a mule and a race horse. They are fed the same amount of food each day. The mule can haul a load all day. A race horse can run really fast for a short while, before it tires. Which one would you take to go racing?

LOL. Depends on the race.. Remember there is no "refueling". And we would have a Race Mule..(Half race horse, half donkey)

[youtube]http://www.youtube.com/watch?v=FRL0yRWyhps[/youtube]

[ISLAMATRON]

exactly smickle.... doubt even these days that any of the F1 engines would last the 24 le mans

[riff_raff]

An Atkinson cycle is generally described as an IC engine that has a greater working expansion ratio than it's working compression ratio. This can be achieved though a crank mechanism that produces a longer piston travel on the power/exhaust stroke than it does on the intake/compression stroke. In theory, this would work on an F1 engine operating at 18,000 rpm, since the power stroke length could not be increased (per rules) and thus inertia loads should not increase. The only open question would be how much effect the modified Atkinson linkage has on the mechanical inertia loads of the cranking mechanism.

The other Atkinson method is to use a late intake valve closure (IVC), so that some of the intake charge is pushed back out of the intake valves by the piston upstroke, thus effectively reducing the displaced volume that the engine uses for combustion. Since engine displacement is regulated in F1, this is the technique an F1 engine would likely need to employ in order to operate with an Atkinson cycle. The reduced trapped charge would reduce peak power. But the lesser power produced would be at a greater thermal efficiency. The reason an Atkinson cycle is efficient is solely due to its greater relative expansion ratio, which extracts more work from the combustion gas.

As for operating an F1 engine on an Atkinson cycle using late IVC, it would operate just fine at the speeds a conventional F1 engine achieves, since there are no mechanical changes other than valve timing.

Toyota and others have produced production engines that use late IVC to operate as an Atkinson cycle under certain operating conditions. This is achieved using variable valve timing.

A Miller cycle is very similar to an Atkinson cycle using late IVC, except that it uses a positive displacement compressor on the intake side in order to reduce the pumping losses incurred by pushing part of the intake charge back out the intake valves. Mazda has produced production engines using a supercharged Miller cycle.

Somewhat similar to the Miller cycle is the Hyperbar cycle. Hyperbar uses early IVC and very high levels of supercharge. The high level of supercharge can be employed because the early IVC allows the trapped charge to be expanded out to a lower pressure on the piston downstroke before the actual compression cycle begins. The added benefit of this is that the charge temperature at the beginning of the compression cycle is also reduced.

Hope this long post was helpful.
Regards,
Terry

[PlatinumZealot]

I remember BMW's VANOS did something similar with the intake valves. Basically leaking out excess air, Injecting less fuel and increasing the expansion ratio as you said. I imagine there is a balance where the gain in efficiency can make up for the loss in power.

I like the one with the linkages better. Since it is a true extended expansion with no loss of gas. That means we can keep the same power levels, and have better efficiency all across the board.

Like running a condenser behind a steam turbine, or a diffuser behind a Gas Turbine. I must admit this topic lead me to take time out to read about the Atkinson cycle for the first time.

[DaveKillens]

I imagine there is a balance where the gain in efficiency can make up for the loss in power.

No

The more you lean towards an Atkinson cycle, the more you lose the kind of sheer power required for competition. In a competition where the race is determined by covering the most ground as soon as possible, is at odds with the concept of efficiency.

[PlatinumZealot]

You have the "linkage" version of the Atkinson cylce, and there is another version where you put in place a turbine that uses power from the exhaust to turn the crankshaft.

The turbine basically does the same thing. Extended expansion to atmospheric pressure for the gases.

The turbine version is very easy to implement in formula 1. It should be more powerful than a standard Engine, and I guess that it will be more fuel efficient.

Right now I am drawing up the one with the multiple links just for fun.

[FGD]

You have the "linkage" version of the Atkinson cylce, and there is another version where you put in place a turbine that uses power from the exhaust to turn the crankshaft.

The turbine basically does the same thing. Extended expansion to atmospheric pressure for the gases.

The turbine version is very easy to implement in formula 1. It should be more powerful than a standard Engine, and I guess that it will be more fuel efficient.

Right now I am drawing up the one with the multiple links just for fun.

The "linkage" version of the Atkinson IS what this thread is all about. Do you read any of the posts?!

[PlatinumZealot]

huh? Did it sound like I didn't know?

I just made a simple statement.

[FGD]

huh? Did it sound like I didn't know?

I just made a simple statement.

Yes, it has read as if you never researched the topic or read any other post. Supercharging of any kind and rotary engines are not permitted in F1. This thread was meant to discuss to the viability of so-called True Atkinson Cycle engines in F1.

[PlatinumZealot]

I didn't mention any rotary engine. I didn't say anything about supercharging or turbocharger.

You have the "linkage" version of the Atkinson cylce, and there is another version where you put in place a turbine that uses power from the exhaust to turn the crankshaft.

When I observed the Prototype made by Honda, I realized one major issue. The design does not suit "V" engines because of the space restrictions on and around the crankshaft.

That is why I mentioned that a turbine can be used to make a regular F1 V8 engine an Atkinson cycle engine by using the power from the remaining power from exhaust gases it to the crankshaft. (No compressor just the turbine.

[ringo]

It should be a more powerful cycle. If it has the same compression ratio and displacement as a typical engine, but greater expansion, that is automatically a greater enthalpy difference.
The combustion chamber being the same, i cant see why it should be speed limited. The biggest question in that regard is the linkage design.