Hint #1: given the changing conditions of temperature and wear how is a triangular piston ring supposed to operate?

Hint #2: how else is a seal to be provided at the corners of the hypothetical triangular piston given the difficulties involved in machining the shapes?

alittle more,

when geometry's converge, so does the stress.

May I add space the cylindrical shape gives optimal performance in the space it takes up.

Just a visual of what I think you are talking about (to support your point!):

I'm sure you could rotate the triangle and get it a little larger while maintaining the cylinder wall minimum thichness, but it would only slightly increase the area.

Good answer, although I suspect that OP might not understand the implications.

Heat loss from the combustion chamber reduces power and efficiency. Heat loss increases with surface area. For regular polygons extruded into a prismatic "cylinder", the triangle provides the absolute worst ratio of volume to surface area. So from an efficiency and power output perspective, it would be the absolute last choice. Adding more sides improves the situation, until an infinite number are used.

In addition, it has a host of structural, weight-to-volume, uniformity-of-expansion, hot spot, machinability, sealing, etc., etc., etc issues. In essentially every imaginable sense, a triangular piston would be the worst possible choice, although shapes like a star would be even worse.

POINT taken.

sorry slack. you already had it covered.

ga from me

The better question would have been what are the disadvantages of triangular piston.

See earlier posts.

A form of a triangle, a Reuleaux triangle, is the basis for the wankel rotary engine, but it's not a piston it's a rotor. There are some advantages and disadvantages to the wankel. It has fewer moving parts, but is less efficient than a piston engine for powering a car. I've heard that Mazda is considering using the wankel as part of a hybrid gas-electric system. Perhaps if tuned to run at a constant RPM it might be more efficient.

Wankel_Cycle_anime

Honda was working on an oval piston design a few years back. I haven't heard anything lately.

This is a question to make you think: "In manufacturing, how would you successfully machine the "cylinder" it fits into?"

EDM

Yes you are correct it is the question to think i have studied in my kinematics during my college days that oval piston has less wear and gives more efficiency.

But my question is cylindrical shape only the shape of piston or some design tried and failed or somebody has idea about it??

I do not have engine development back ground. But I think you would have to narrow down on, What type of efficiencies are you looking for?

Combustion, exhaust, wear?

say i studied that if you use an oval piston your friction losses will get reduced which results in increase of power and fuel consumption.

If there is any increase are they enough to warrant the increase in cost of manufacturing. A round cylinder bore is relatively easy to machine compared to an oval.

Pretty slick idea. Honda thought so back in the 1970's - http://world.honda.com/history/challenge/1979pistonengine/

"When I look back at it, I'm not sure if we were experimenting with cutting-edge technologies or obsessed with foolish ideas," recalled Toshimitsu Yoshimura, an engineer involved in the development of the NR500's oval piston engine.

I have seen rectangular and square "pistons" in very specialised applications (Vacuum pumps) and so irregular shaped pistons are not impossible.

The advantages (possibly) of having alternate pistons orientated each way might lead to a shorter length of engine for the same displacement and might even mean less material in the castings.

The disadvantages relate to the processing difficulties in making such components to the necessary clearances.

Ddo not be afraid to ask the questions that challenge the boundaries. There is no shame in such, provided that we learn and move forward. Be prepared that some questions end up being folly and can be left behind on the journey as experience, unlike some who become fixated on a hoped outcome that cannot be.

it would be almost impossible to design a compression sealing system for a trianglular piston. what would advantage of a triangular pistion? the piston would have hot spots, expansion differentials, wear patterns ,bore misalighnment, ect.

sounds like a bad idea.

Svg.L,

There are no advantages to a non-round piston/cylinder configuration.

Why ever would you think that there were?

"Hello, Lyn-Door Industries. How may I help You?"

Ah yes, I am looking for a piston ring compressor for my 2013 Toyota Corolla.

Do you know what engine is in it?

Yes it is the 1.8 L 4 cylinder.

......Oh, I see. Do you know the Engine code, or the shape of the piston?

Yes, it is the Z code engine.

......Ohhh, That is the engine with pistons the shape of triangles. Do you happen to know the dimensions of the piston?

No.

Do you know the angels of the piston?

No. Why do you make buying a simple ring compressor so complex?

We at LynDoor™Industires always ship 3 sets of triangular rings. They have a nasty habit of breaking at the angle when they are expanded for installation onto the piston.

They have a nasty habit of breaking at the angle when they are expanded for installation onto the piston.

So what LynDoor™Industries did was to revise the instruction manual, which consisted of this little addition;

Install until Triangle breaks, when it breaks you now have conformation the install was successful and complete.

Yes, triangular pistons, square crankshaft and pentagonal wheels. Can't think why it hasn't been done. It's the type of thing that Michael Kroll, Patent Agent, would be only to be pleased to patent and relieve you of thousands of $.