Welcome! Log In Create A New Profile Recent Messages


Double acting staggered 90-degree V4 Double Crank Rod engine

Posted by leeputman 
Double acting staggered 90-degree V4 Double Crank Rod engine
June 14, 2007 02:42PM
Has anyone ever head of the double acting staggered 90-degree V4 Double Crank Rod engine?

I saw this thing on some guys web site and it looks pretty neat. I would love to see if there are any construction plans around for a full size engine. One big enough to drive a car.

Anyone have any suggestions? thanks, Lee
Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 14, 2007 03:14PM
Hi Lee.

Sounds like you have been out to my site.


No Plans. That crank rod engine is just a concept and may have some binding problems with uneven heating. I think it is a form of a scotch yoke mechanism.

Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 14, 2007 11:57PM
Andy, I think you are right, as in the scotch yoke mechanism problems of the old Bourke 2 cyl opposed 2 cycle gas engine from the 50's or so. Among other things, when using a scotch yoke there tends to be a lot of stress placed on the bushings at the bottom of each cylinder or wherever the flexing of the scotch yoke is applying the thrust which generates heat with no useful purpose as well as the high point loading of the bearing rolling back and forth in the yoke. There are better ways.
Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 15, 2007 08:03AM
Andy, yes, I have been trying to contact you for a couple of years now. BTW, the e-mail link from greenhills.net does not work.

But now i am disappointed. I thought that all of these steam engine mechanisms had been used somewhere at some point in time. I just Googgled Scotch Yoke mechanism and got a nice little java script presentation similar to yours. It looks surprisingly like the drive for my Sheldon Shaper.

Would the eccentric crank engine be one of those mechanisms that needs to operate a very high rpm's in order to work properly?

I was hoping to convert a Honda CX500 motorcycle engine into one of these. Does not sound worth the effort.

Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 15, 2007 08:49AM
You may want to check out this site.


Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 15, 2007 09:38AM
rural, It's not a sliding yoke exactly. Look at the anamations of the mechanism. There pumps using that same mechanism.

Where I have doubts is at mid-stroke. For it to work the excentric center must pass through the crank center. So is the excentric and crank get out of tollarance due to heat expansion it would put a bind on the cross slide.

Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 15, 2007 11:14AM
Lee, The excentric is sort of a double conecting rod. A very short conecting rod whoes center to center distance it equal to the crank throw. The stroke is 4 times that. Say the crank throw is 1 inch. A normak engine would have a 2 inch stroke. But the crank engine has a 4 inch stroke.

There is no problem passing through the center as far as a dead spot. One excentric can not stay centered as the other conected excentric being held to a path at 90 degrees forces it movement on through the center.

As I stated though I think there could be a problem at that point of the crank throw and excrent through differ to much because of heat expansion. A few thousands tollorance can designed in.

Origionally I didn't think it was a scotch yoke. But I found a scotch yoke example, I think a BMW design, that uses the same excentric mechanism.

[www.sliderengine.com] First two of the three.
[www.sliderengine.com] first and third in this one.

George seams to think there is some problem. Though I don't know what he is talking about exactly. I couldn't find where he ever explained the problem he mentions. Note the engine designs in the above links uses the double excentric same as in the crank rod engine. Though one excentric is just constrained to it path by a slider or linkage and not driving a piston. I have also found pumps that use that same mechanism.

I am planing give it a try. I wish George would explain what he was talking about.

It has the potential of reducing the size of a double acting engine. I have some proE designs for a crank case and crank. It's a neet design. The crank case is sections that fit together like a 3D jigsaw puzle.

An anamation of the crankcase for 6 cylanders. [www.steamautomobile.com]

If you consider a section to be a V. Then there are two crank case parts to each section. All the crankcase parts are identical. Each section uses two parts. The slider side of each part go to gether at 90 degrees. And then thoes may be mated to the next section. You can see two large tabs and corosponding indentations on the slider side of the section closest to the camra. There are also tabs and indentations to mate the sections together. An engine of any number of cylanders can be but together.

Four long bolts would go through all sections to hold them together. There are also end caps that would go on the end. The section closest to the camra was made invisable for the anamation. So what is seen in the anamation is 5 sections and no end caps. You can see the wholes for the cylander mount bolts Each crank part has two of these. You can see eight of thoese. The end caps have two as well.

Its and older file. The curent parts have oil/dirt seals where the piston rods come out of the parts that is not shown in that anamation.

The mechanism could be used for a double acting engine or a single acting engine. The main thing in both cases is the seperation of the expander from the crank case.

Also one would not have to use a slide mechanism. See the engine links above. Some use linkage to force stright line motion. An orbital gear system could also be used to force the excentric rotation and provide stright line motion of the excentric paths.

Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 18, 2007 07:27AM
I looked at the two pages you referenced, slider engine. It looks like a very nice setup. I also understand what you mean about the critical point where the eccentric center passes through the crank center. I can not help but think "radial engine" with the design using an early cutoff. Keeping the engine single acting and compact. The crank could be quite stout and maybe even have a secondary low pressure bank.

My application is for running a generator in a hybrid car application. Have you heard about the guy that has turned the 4 stroke IC engine into a 6 stroke? He injects water into stroke five to scavenge heat from the internal combustion cycle. I have always marveled at the energy that car pump out the tail pipe. SO if a hybrid car had a small IC engine to run a generator and the exhaust ran through a boiler to power a small hi rpm condensing steam engine, what kind of efficiency would you get. This may be enough to allow the use of fewer storage batteries and be able to supply 100% of the cars running power once heated up. Useful for those that do not use the car in stop and go driving where a normal hybrid is most efficient.

A lot of ideas in one small post. Thanks for your input.
Re: Double acting staggered 90-degree V4 Double Crank Rod engine
June 19, 2007 01:34PM
Hi Lee

There two six stroke engines I know of. The one you mention which is a 6 cycle engine that add has a steam cycle the lats two strokes.

The other is a duel piston engine. I puts a 2 stroke engine on tope of a 4 stroke engine (6 strokes). The two stroke runs at 1/2 the speed of the main 4 stroke. Both pistons develop power. The upper piston also acts as a valve. It is proted like a 2 stroke engine.


Sorry, only registered users may post in this forum.

Click here to login