Sport Pilot wrote:
>
> Don Stauffer wrote:
>
>>Sport Pilot wrote:
>>
>>>Completely wrong, the Otto cycle has nothing to do with four stroke
>>>engines. Don is right its not four cycle, I used it incorrectly. The
>>>Otto and Diesel cycles are actually refering to the thermodynamics
>>>chart of temperature pressure and volume, they invented their cycles on
>>>paper and books, the engines we use are only close approximations. The
>>>two stroke ignition engine uses the Otto cycle as it is has the four
>>>phases of intake, compression, power, and exhaust, and the pressure is
>>>not constant. The Diesel two stroke is a Diesel cycle because it also
>>>includes the same phases and the fuel burns at a fairly constant
>>>pressure.
>>>
>>
>>I guess I'd quibble with the statement that the Otto cycle has nothing
>>to do with four-stroke engines- it was the first successful cycle to
>>incorporate four strokes. yes, there are other four stroke cycles, but
>>the Otto cycle is still by far the most common. There have been several
>>other four-strokes, several two-strokes, at least on six stroke- I
>>suspect several also.
>>
>>New IC engine designs are among the most numerous US patents. Just
>>because something is patentable, of course, does not make it good or
>>successful, and most of these patents were for approaches that offered
>>insufficient advantages.
>>
>>BTW, as I understand the new Miller cycle, I don't consider it a truly
>>new cycle- just a clever mod on the Otto. I don't consider the Otto
>>cycle to require valve openings at closings at the top or bottom dead
>>center, exactly.
>
>
> The confusion is that Otto invented the first four stroke engine and
> called it the Otto cycle, not because of thermodynamics but because he
> put it in a motorcycle. However the thermodynamic cycle can be
> reproduced with a two stroke engine. Its just that the intake and
> exhaust cycle's are much shorter.
>

I am not sure what you mean by exhaust and intake "cycles". There is
one cycle- the actions that the engine goes through before everything
repeats. Do you mean the portions of the cycle during which the exhaust
and intake take place- they definitely take less crankcase revolution angle.

In the Otto cycle it is easy to break it down into four operations, each
lasting one stroke. A two-stroke is more complicated, because it still
has (existing, contemporary ones, do anyway) four seperate functions of
intake, compression, combustion and exhaust, but have to do it in two
strokes.