# Un-Named Engine



## vederstein (Sep 12, 2021)

On to the next idea for my series of "steam" engines with strange layouts.

I notices on my last project, that back-driving the valve cam resulted in shaft rotation that wasn't too hard.  Therefore I think I can have an engine using an offset circular cam instead of a crankshaft.  I could've done a "normal" inline cylinder layout, but why not make it strange?!?

Therefore, I have each crank cam - piston section tied together with spur gears.  In the middle I have a too large flywheel.  (It's what I have on order).  The engine will nearly fit within the 4-1/2" diameter of the flywheel.

Here's some renderings of the short block.  (I haven't started any of the valving yet.)

Comments are appreciated.


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## vederstein (Oct 24, 2021)

Several weeks later, I've spent some more time on the motor.

To make it stranger, I've changed the layout to a four-square layout.  It has two crankshafts, one flywheel shaft, four cylinders and four spring loaded valves.

Renderings and computer animation follow:


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## Richard Hed (Oct 29, 2021)

vederstein said:


> Several weeks later, I've spent some more time on the motor.
> 
> To make it stranger, I've changed the layout to a four-square layout.  It has two crankshafts, one flywheel shaft, four cylinders and four spring loaded valves.
> 
> ...



Did you create thiS?  Cool


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## vederstein (Oct 30, 2021)

Richard Hed said:


> Did you create thiS? Cool



 Yup.

I'm a mechanical designer of industrial equipment by trade. I spent nearly ten years designing custom leak test equipment, mostly for the automotive industry.  For the past 6+ years I've been designing equipment for the processing of circuit boards.

As usual with my engine designs, once I successfully build the first one get the bugs out, I'll post the design files on this forum.

...Ved.


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## Richard Hed (Oct 30, 2021)

vederstein said:


> Yup.
> 
> I'm a mechanical designer of industrial equipment by trade. I spent nearly ten years designing custom leak test equipment, mostly for the automotive industry.  For the past 6+ years I've been designing equipment for the processing of circuit boards.
> 
> ...


I can hardly wait till you work the bugs out.


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## LorenOtto (Oct 30, 2021)

vederstein said:


> Yup.
> 
> I'm a mechanical designer of industrial equipment by trade. I spent nearly ten years designing custom leak test equipment, mostly for the automotive industry.  For the past 6+ years I've been designing equipment for the processing of circuit boards.
> 
> ...


I will be watching also, keep posting your progress.


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## Steamchick (Oct 31, 2021)

The only observation I can make is the friction losses of the cam-shaft and followers may be significantly high, compared to conventional crank arrangements? - This will be interesting to see when you cut metal. E.G. a "conventional" slide valve is driven from an eccentric, rather than a cam with return spring - but I don't know "why" - except for frictional reasons? (= one of the biggest problems for "conventional" poppet valve actuators of modern "friction optimised" engines.).
But the advantage of cams over eccentrics is that an eccentric gives you a regular sinusoidal motion, whereas the cam profile can provide an infinite variety of operation timings for the valve(s). - I guess you plan to exploit this advantage in your design to improve gas flow through the piston valve? - e.g. for early cut-off of the supplied steam, and appropriate exhaust maximised for  purging and allowing for end of stroke cushioning, or whatever you choose?
I guess you are looking for very high revs for this engine?
K2


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## davidyat (Oct 31, 2021)

Ved,
   I always love your "outside the box" thinking.
Grasshopper


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## vederstein (Oct 31, 2021)

Steamchick said:


> I guess you plan to exploit this advantage in your design to improve gas flow through the piston valve?



I'm not thinking that far into the future.  If the damned thing runs, I'll consider that a win.

...Ved.


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## vederstein (Jan 9, 2022)

I have two the engine running on compressed air on two of the four cylinders.  As Steamchick recognized, internal drag appears quite high because I require fairly high pressure ~70 psi to make this thing run on the two cylinders.

I hope to lower this pressure with the addition of pistons three and four.  Considering the thing leaks all over the place, I need to seal the thing:  Piston seals, cylinder head seals, port cap seals, etc.

As shown in the following video, it works, but there's a ways to go.

...Ved.


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## Steamchick (Jan 10, 2022)

Hi Ved... Maybe I was over-critical of the frictional aspect? - It seems lower than perhaps I expected, probably due to the roller followers...? 
But you seem to have a lot of exhaust "chuff"... as if you are not making the most of the air pressure expansion.? Of course, if designed for air it has different valve timing to when designed for steam, as the superheat in steam can do so much more work than simple adiabatic expansion of air... and I think you said you were designing for steam?
And 4 cylinders running will carry their own friction, but reduce the overall losses as a percentage of the input work (The "common" friction). Have you tried a squirt of oil in the intake, to improve piston sealing and reduce friction? Results can be amazing, as it will temporarily improve sealing and minimise losses ...
K2


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## vederstein (Jan 10, 2022)

Steamchick said:


> you seem to have a lot of exhaust "chuff



Currently there's a significant amount of leakage because at this time nothing is sealed.  I can adjust the admission and exhaust timing via the adjustment screws on the valve stems.  What I cannot do with this design is adjust admission and exhaust dwell which is set.  (i.e. I can move the valve's sine wave motion left or right, but I cannot change the amplitude).

Once I get around to sealing the motor "chuffing" should be drastically decreased.  There's significant work to do to finish this thing.

Also, my designs are generally so "out there" that I just consider a running engine a win.  That's just fine with me.  I'm making expensive toys.  The primary purpose of these machines is to sit on a shelf and collect dust.  They'll never perform any "real" work.

When the weather gets warm, I may hook this thing up to my boiler and run on live steam just to see if/how it runs.

Another way to put it: I do enough design optimization as my job.  I just don't have the patience to go that far with my hobby.

...Ved.


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## Steamchick (Jan 10, 2022)

Hi Ved... "When you retire from paid work...." maybe you'll do some "tuning" of your designs. (I come from a very similar professional-background attitude! - Agree your sentiments!).
Meanwhile, I think the engine looks great! Well done, and carry-on! - I want to see the final job running... even better when you steam it.
I now find (retired) that I have the time to do a "proper job" as the "occupation" of modelling uses my time (and brain) and supplies the "reward" of better results than I previously had time to achieve.
But when you retire, you'll find that the "Occupation + Reward" from modelling is OK replacing the "Work + salary", but the "Company" is on-line (like this chat line) instead of being face-to-face at work.
Good to have your company!
K2


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## Charles Lamont (Jan 11, 2022)

Here's an idea for the next extension of this. How about a linear motor, opening the cam out into a sinusoidal rack?


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## Steamchick (Jan 11, 2022)

Or Using a Scotch yoke? Will it work on a cam?
Or a trianglelliptical rolling piston in a double hemi-oblongigated shape?
K2


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## vederstein (Jan 11, 2022)

Charles Lamont said:


> ow about a linear motor, opening the cam out into a sinusoidal rack?





Steamchick said:


> Or a trianglelliptical rolling piston in a double hemi-oblongigated shape?



You realize, compared to many in this hobby, I suck at this. Right?!?!

(BTW:  I do understand you're describing a Wankel engine.)

An idea that's been floating in my mind for some years:

I was at a antique farm equipment show and saw this hay baler with the ram reciprocating movement run by a chain.  The design struck me as interesting because you could obtain a super long stroke without some god awful huge crankshaft.  The idea would be to take that idea and invert the mechanism such that the ram becomes a piston and powers the chain.   I never really deep dived into the concept, but it's always there hidden in some crevice of my mind.

...Ved.


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## Steamchick (Jan 11, 2022)

Hi Ved, No offence intended - it was more a bit of rhetoric at the way we all propose different designs to the ones being presented ... 
And you were right - I was suggesting a Wankel - That wonderful design that overcame all the difficulties from 100 years of linear versus rotary motion.
As to the "pushing chain" idea... Nissan - in their CVT - for reasons I cannot divulge (ex. employee - bound by professional ethics) - made a "pushing chain" type of belt to connect the pairs of cones in the CVT. (Millions have been made and successful in cars). They also got the oil companies to develop a special fluid that both lubricates sliding surfaces, and "Sticks" when under severe contact pressure - to resist slippage and heat (wasted power) at the contact with cones. - So maybe a "pushing chain" is what you need? - I think it essentially locked when compressed, yet disengaged when curved... say no more. 
Otherwise a rack and pinion does a similar motion. - I think Otto's first engine used a rack and pinion instead of crank - so that has been done before as well! But if you have an original idea, don't tell us - patent it! - Could be worth a fortune!
Charles' idea could be a linear form of a swash-plate... as used on the wierd but compact Australian engine... I can't recall the name of the design I should know.... (An age problem?)
4 cylinder australian engine swash plate - Bing images 
4 Cylinder horizontal air cooled wobble plate engine! | Smokstak® Antique Engine Community
And even that isn't new...
Axial Internal-Combustion Engines. (douglas-self.com) 
But this was a bit different:
Cyclone Power – How it Works 
K2


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## vederstein (Jan 15, 2022)

I removed all the pistons and cut in an o-ring groove.  Then I reassembled the engine with all four cylinders, two camshafts, and eight eccentric cams.  

I now know that elimination of friction is more important than having a sealed engine.  I was able to get it run down to about 55-60 psi, but I think that's the limit.

The next step is to remove all the set screws that are acting as plugs for the air/steam porting and put thread sealant on them to eliminate losses there.  But that's another day.

Knowing what I know now, it may have been advantageous to offset the piston from the centerline.  This would result in a quick return mechanism for the cam allowing a longer power stroke.  It would've been harder on the cam because the piston return would have higher accelerations, but it may have been advantageous.

I'm going to stick with Steamchick's comment about eccentric cams just naturally having naturally high friction.

I'll make a base for the thing.  I'm just going to go by the seat of my pant on that and it will not have any drawings.  Then it gets paint and the aforementioned plug sealing.  Then this puppy will be complete.

I didn't make many changes from my original design.  Drawings and CAD models will be available for this engine on this thread/forum soon.

...Ved.


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## johnmcc69 (Jan 15, 2022)

I always enjoy following your posts Ved. Interesting designs for sure, keep 'em coming.

 & thanks as always for freely sharing your plans (& frustrations).

 John


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## Steamchick (Jan 16, 2022)

Hi Ved, I understand that the "steam engine eccentric" - being a perfect sinusoidal motion - is MUCH lower friction than the Poppet-valve cams of ICE engines - Not sinusoidal, but determined by the cam-follower relationship - but not something I have ever quantified. 
Also I understand that the O-rings applied by others (Brian Rupnow is one expert on this I think) basically have effectively zero interference with the bore, on their OD when assembled onto the pistons. All the radial load for sealing against the bore comes from the gas pressure at the bac of the O-ring, and the dynamic forces cause sealing of O-rings on either top or bottom face of the piston groove. Any assembly friction from O-rings on pistons installed into the bores should be absolutely minimal, but just touching. Brian R has successfully used O-rings on his ICE engines, so maybe he can advise more?
Your post #18 implies it runs with the O-rings installed, but needs 55psi to break the Stiction? (Static-friction).
What was the lowest pressure when without O-rings?
At 55 psi, the force on 1 piston can be calculated, so the friction equals that at zero movement. With some geometry, you can possibly deduce the difference between with and without O-rings as the "stiction" of Cam+ O-ring, versus Cam alone, to give some clues as to what is going on. Coefficients of friction at zero slip can be typically 0.3 from steel (from loco traction on rails) I think? So where forces are eccentric, you can resolve them from pressure onto the friction contact and pressure perpendicular to the line of contact force, to gain some understanding of where and how much Cam friction exists? Perhaps an excel spreadsheet at 5 degree cam-shaft rotation intervals can quickly indicate the worst point in the motion (the sticking point), that a cam designer would try and move to reduce the peak contact force, to optimise the motion, hence the shapes of regular ICE cams... Then with the CAD you can consider the off-set alignment - as you suggest - to reduce the "power-stroke" stiction, and replace with an increase in stiction where it doesn't have any material effect? Alternately to the 5 degrees of iteration, you can use steps-of-stroke.
This should give a rationalised approach to the design, and you can use the Pup to gain the real comparison between calculations and the real job! (there are always "other factors" ignored in numerical modelling that sometimes need to be measured and input to the calculations).
Note: "post-Victorians" considered off-setting bores from crankshafts on many ICE engines to reduce piston side thrust during the firing stroke. Something I wanted to do on a "mark 2" design of some equipment I designed for one job. But it wasn't a problem in service, so I didn't get the second bite at the design. All the calculations I did back in the 1980s were "pre-spreadsheet", so were on reams of paper with manually plotted graphs! Shortcuts with constants were necessary, so the slide rule (the quickest calculator around) could be used as a conversion scale to read-off a set of values against single variables. Much faster than "Texas instruments" programmable calculators! And clearer to see the results. Who needs computers?  - Except for more complex iterations.... We have brains.
K2


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## vederstein (Jan 16, 2022)

Here's a cross section of the engine at its most advantageous torque.  As you can see from the free body diagram, the the torque "arm" (L) is only 0.066".  So the torque applied to the crankshaft from each piston is:

T = L * F
T = L * Press * A
T = L * P * pi*r^2
T = 0.066 * 55 * 3.14 * .313^2
T = 1.1 in-lbs











.187

If the piston is offset from the camshaft, the "torque arm" can be significantly increased but it's to the detriment of higher cam forces on the return piston stroke.   In the illustration below I offset the the piston 0.188" which is the centerline of the cam at 90 degrees.  You can see here that the "torque arm" goes from 0.066" to 0.188" which would change the applied torque from 1.1 in-lbs to 3.2 in-lb at the same pressure, a 290% increase in torque which would decrease the air pressure requirements from 55 psi to a more reasonable 19.  The stroke would increase significantly as well.






Based on this analysis, it appears the biggest improvement would be a change in geometry.  But I'm not going to re-make this engine.  Remember back from the beginning:  if it runs, it's a success.

I'm always trying out new ideas on this hobby.  I can leave it to other to optimize...

...Ved.


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## vederstein (Jan 16, 2022)

I've started a different thread with the plans for this engine.  You can obtain the design files for this thing here:






						Four Square Engine Plans
					

This is a continuation of the "Un-Named Engine" thread.  I've since actually named this thing "Four Square".     As promised, here's the plans.  I highly suggest you read up on the Un-Named Engine thread.  This design requires significant air pressure to run because of the engine geometry.  It...




					www.homemodelenginemachinist.com


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## Steamchick (Jan 17, 2022)

Ved: Your post #21. Well done! A good bit of design work! Noting that the line of force is actually at an angle to the axis of the piston (Radial in the roller follower, but not in the line of the piston), this force can be resolved into the thrust from piston through the cam follower etc. to camshaft bearings, but also a thrust that is a reaction perpendicular to the axis (motion) of the pistons. This side thrust is higher from the high pressure of the air on the power-stroke, but lower on the return stroke when it is only working against the mass of the piston, spring, and residual pressure as the cylinder is evacuated. This side thrust on the piston can also be calculated and plotted to optimise the friction to a minimum, by reducing the peak value (power stoke) and allowing an increase of the side thrust on the piston where is is likely to be significantly lower - I.E. the return stroke.
Perhaps this design work will encourage you to make a second model, with "optimised" geometry" for power/friction, and if you can measure the performance of this engine, then compare the performance of the "optimised" engine, you'll appreciate how good this engine can be. But I concur with your drawing a line to define success. It runs, it achieves objectives = Success!
But the mental exercise and drawings of alignment on cams versus piston roller you have done has already given us most of the answers. So again "Well Done sir!"  - and thankyou for sharing your time to explore some question I had raised. I do appreciate the work you have done.
K2


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