"Pivotal Engine"

[Peter S]

Here is a website I just came across, will interest those who like engines - here is another type to add to the many that have been tried.

http://www.pivotalengine.com/index.html

[Spin Doctor]

Is it just me or does this seem like it would much higher internal friction due to the "piston" shape

[Spin Doctor]

Is it just me or does this seem like it would much higher internal friction due to the "piston" shape

Sorry about the double post

[This message has been edited by Spin Doctor (edited 05-12-2004).]

[SJorgensen]

No, I don't think that the shape of the piston is going to be a friction problem. Actually this engine is similar in some ways to one that I have designed and am building. The reason why friction is lower is because the piston is not thrown against the cylinder wall anywhere in the stroke. Therefore the cylinder won't tend to "bell out" like the standard engine. Consider the forces on the piston that are due to the angle of the piston rod. Plus the difficulty in cooling a standard piston. Manufacturing a curved cylinder or a section of a torus would be one of the challenges.

[Sprocket]

Not "pivotal" but here's another interesting engine http://www.rcvengines.com/model_home_page_full.htm Seems the cylinder rotates around the piston, RCV is rotating cylinder valve. The prop shaft is an extension of the rotating cylinder. High torque because it is geared 2:1

[CCWKen]

I guess you missed this statement:

"In a 'Pivotal' engine the only components subject to wear are the chamber surfaces, the compression seals and the bearings."

And just how is this NOT wearing "cylinder" walls?

Also; It would seem that this would be a throw-away engine. Who could do the re-machining necessary to rebuild it. Cylinder Inserts?... New "piston"? ... New bearings? How is this engine any better?


[This message has been edited by CCWKen (edited 05-12-2004).]

[Spin Doctor]

There have been a great many attempt to come up with a replacement for the basic internal combustion engine layout almost ever since they were introduced. The sinusodial, the various barrel designs and others. The thing that strikes me now is I wonder how the mass of this piston compares to a conventional one of similiar displacement.

[canonicalman]

It's hard for me to believe that the pivital engine piston achieves a sufficiently good seal to the combustion chamber to prevent significant blowby. The emisions problem is the major issue with two-stroke engines. How well emisions is addressed will determine the future of this engine.

The critical factor claimed is "The 'Pivotal' engine oil usage is only 10% of the level required by a conventional two/stroke engine. This rate of oil consumption is comparable with the oil consumption of a four/stroke engine before the additional saving from not having oil changes is factored in." So, this engine should use less oil in total than either a two or four stroke engine if this claim is correct.

Also the claim that "the compression seals... do not protrude into the port openings." seems to be contradicted by the animations. If the seal does not cross the port opening at some point, how does the exhaust gas reach to port?

Another important claim for those of use who can't stand the constant drone of the two-stroke is "The exceptionally low level of mechanical noise is immediately apparent".

I'll give this one a definite maybe. Needs some rigorous testing to truely determine any benifits.

[ibewgypsie]

Nothing I have saw so far beats the exceptional economy of a triple expansion steam engine.

I experimented with a dual fuel engine once.. I am still confused why our motors don't go whoosh shooh.. whoosh shooh...

Not enough money to put one into a auto.. I searched for a a investor.. no luck.

David

[Spin Doctor]

Going through the site has anyone else noticed that this is a couple of years old. They were supposed to be at Oshkosh in 2002