Otto Cycle and Diesel Cycle

Hi Guest,

The Otto cycle, or 4-cycle, engine is not a constant volume engine. A Stirling engine comes closest to being a constant volume cycle since the working gas is just transferred from the hot end to the cool end (of the cylinder in the case of a single cylinder design) but without actually changing the volume of gas. Even in the case of multi-cylinder Stirlings, the working gas is just transferred from a "hot" cylinder to a "cool" cylinder. Still, same volume.

The 4-stroke cycle is called Otto in honor of Nikolaus Otto who invented it in 1876.

I'm not sure what you mean in your second question about diesels.

Regards,

-John

Diesel engines are two-cycle engines, kind of like the ones that run those noisy leaf blowers. Diesel engines use ports instead of valves and no spark plugs, except glow-plugs which just help to get the beast started.

Diesel was also a guy, I think his name was Richardo Diesel.

Vermin

Most diesel engines today use the 4 stroke method with valves. Early Buda and later Detroit Diesel used the two stroke method. Cat and cummins use 4 stroke, as do yanmar, Kubota and even the lawnmowers are 4 stroke, B&S.

Most of the newer use the direct injection at the top of the compression stroke and get ignition from the heat of compression, The glow plug is only used for the intial heating of the first few charges of air to get the engine up to running temperature by creating a hot spot for the fuel to vaporize and ignite from.

Ric

Ric,

Thanks, I did not know that these used 4-stroke technology for diesel engines!

I assume you never visited mainland Europe: half of the cars and every truck has a 4stroke Diesel engine here.

Nope, but I still wouldn't have known they were 4-stroke, Mr. Happyfeet.

The Otto cycle is a constant volume cycle: the combustion takes place at a certain point in the cylce and (theoretically) is immediate and complete. The fuel is burned in a constant volume environment.

The Diesel cylce burns the fuel so that the pressure remains constant during a part of the cycle.

There are many more differences But Diesels name was Rudolf

The Diesel engine was invented before the Otto, but the Otto cycle was much easier (in fact it was a way to deal with the problems Diesel had to get the engine reliable)

Sorry Gwen,

You are correct! I spoke before putting my brain in gear. Sorry.

John

"I don't like penguins, much! They're always trying to take over Burma!!!"

Any one can google, copy and paste... To save you the trouble ....

In the diesel engine, air is compressed adiabatically with a compression ratio typically between 15 and 20. This compression raises the temperature to the ignition temperature of the fuel mixture which is formed by injecting fuel once the air is compressed.

The ideal air-standard cycle is modeled as a reversible adiabatic compression followed by a constant pressure combustion process, then an adiabatic expansion as a power stroke and an isovolumetric exhaust. A new air charge is taken in at the end of the exhaust, as indicated by the processes a-e-a on the diagram.

Another example of a constant-pressure cycle .

Hi oomsarel,

You said: "Any one can google, copy and paste... "

"The 4-stroke cycle is called Otto in honor of Nikolaus Otto who invented it in 1876." Just included for info purposes. Not facts I keep right ready to spit out at a moments notice. Besides, google and wiki are great reference and concordance sources. You should try them sometime...

Cheers,

I was referring to myself googling coppying and pasting... in rely to the post and not what you said... I don't know much on the facts of the subject, I only understand the way a 4 -stoke engines works. Sorry if you were (unnecessarily) offended...

No offense taken my friend.

-John

hi......

since the heat is added to petrol engine at constant volume so the otto cycle is also called as constant volume cycle...

and for diesel engine heat is added at constant presures so the diesel engine is also called as constant pressure cycle.....

Dduh! Why duz it madder? Purely academic.Someone has 2 much thyme on der hanz.

"2 much thyme" ? are they growing herbs?

I think he is experimenting with green fuels