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Slightly off topic. New Diesel design

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Topic: Slightly off topic. New Diesel design
Posted By: Charlie (NC)
Subject: Slightly off topic. New Diesel design
Date Posted: 23 Feb 2011 at 6:35am
I saw this and thought some others would enjoy seeing it too.  Having spent many hours behind a Detroit diesel and knowing the negatives of two stroke diesel engines I don't see how this thing is going to hold together or how they will be able to keep it oiled properly but it sure enough is interesting and the US Army thinks enough of the idea to pay for a prototype.  We'll see how it turns out.
 
http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder - http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder



Replies:
Posted By: Charlie (NC)
Date Posted: 23 Feb 2011 at 6:36am
I would love to hear everyone's thoughts on this.


Posted By: Lonn
Date Posted: 23 Feb 2011 at 6:49am
Kinda similar to this  http://en.wikipedia.org/wiki/Opposed-piston_engine - http://en.wikipedia.org/wiki/Opposed-piston_engine

but more like this  http://www.ecomotors.com/ecomotors-internationals-opposed-piston-opposed-cylinder-engine-promises-revolutionize-commercial-ve - http://www.ecomotors.com/ecomotors-internationals-opposed-piston-opposed-cylinder-engine-promises-revolutionize-commercial-ve

Then there is the free piston design.


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Posted By: Chris/CT
Date Posted: 23 Feb 2011 at 6:50am
Interesting video. Sounds promising with a few years to go to work out the details. At that point they will see if it will work or not, big gamble, They are on the right track, eventually new engine designs need to be designed. 


Posted By: Byron WC in SW Wi
Date Posted: 23 Feb 2011 at 7:11am
Lot of smoke an mirrors at this point.  Subaru and several airplane engines are opposed.  The only difference in  their system is they add another piston.  Big difference I know but it adds moving parts.  Moving parts mean friction and more potential problems.  If I were to see a new engine design I'd like to see one that runs on vegetable oil straight from the factory.  Or see one that is designed to run on ethanol instead of these gas engines converted to accept ethanol.  But, IMO, eventually we'll all be driving electric vehicles with fuel cells added for range.  Current engine designs have been tested and developed for 100 years.  In a 50 years, when new engine designs will be mature, will we have any oil left of will it be price competitive?




Posted By: TexasAllis
Date Posted: 23 Feb 2011 at 7:27am
I think these guys are on to something but time will tell when they prove it out.  The engineer said the two bore model was the equivalent to a four cylinder inline diesel so the moving parts are the same.  If the engine is truly balanced then it should outperform and outlast current diesel designs.


Posted By: Charlie (NC)
Date Posted: 23 Feb 2011 at 7:28am
I just don't see how the thing is going to stay together with two external connecting rods with no way to splash or spray oil the wrist pin except by pumping the oil through the connecting rod (I'm assuming that is what they intend to do)   Also, assembly of those rods is going to be critical because they both have to be set up exactly the same to keep the piston in line.  Add to that the fact that those connecting rods are running in tension instead of compression like typical rods.  The design engineer has had a long
career building engines for VW.  Maybe he's on to something.  My guess is he found a way to make some money off the US taxpayer.


Posted By: Stan IL&TN
Date Posted: 23 Feb 2011 at 7:30am
It's going to take time to iron out some major problems with lubrication and heat rejection and it may never pass exhaust emission standards.  Government is I believe exempt from those standards and they do have our money to spend on it.

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1968 one-seventy

1956 F40 Ferguson


Posted By: Charlie (NC)
Date Posted: 23 Feb 2011 at 7:36am
I know that there have been ship engines built that were horizontal opposed piston design but those were huge, slow moving engines and weight is not an issue with them.


Posted By: Orange Blood
Date Posted: 23 Feb 2011 at 8:35am
What bugs me, is that he kept saying that a two cylider version of his engine is like a four cylinder standard engine.  If my physics is right, you still only have one power charge, or one explosion.  In a typical fixed head engine, all of the power from the explosion is driven down on the piston, in this engine the same explosion is divided to drive two pistons, now add in that you have extra moving parts and friction is esentialy doubled, the engine should actually produce less HP per explosion.  Are they getting all of their efficancy from balancing things out?  Where am I going wrong, it sure sounds like it has been preliminarily tested and the HP claims sound like they have been observed.  

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Posted By: Tramway Guy
Date Posted: 23 Feb 2011 at 9:13am

The German Junkers Jumo 205 Aircraft used an opposed-piston Diesel engine.  Two crankshafts, one at the top and one at the bottom, geared together.  Worked pretty well...also used ports like this one does.

http://www.enginehistory.org/Diesels/CH4.pdf - http://www.enginehistory.org/Diesels/CH4.pdf


Posted By: Charlie (NC)
Date Posted: 23 Feb 2011 at 9:13am
I agree with you completely.  It looks to me like he is taken a given fuel charge and split the power obtained from it in half and sending it through twice as many moving
parts (actually more than twice) to get it to the crank shaft.  The only advantage I can see is that engine is therotically more inherently ballanced.   If that is what he hopes to gain why not spend his effort on improving turbine engines or the wankle rotary design.
I don't know where he is getting the great economy improvement.


Posted By: wfmurray
Date Posted: 23 Feb 2011 at 9:14am
Don,t see mutch advantage over  what we already have. Might be a way to get high compresson in a two stroke engine with shorter stroke. Off subject: I once saw something  about an engine that worked on a wobbleing plate  with cyl on each end . Kind of like a hydl pump. Have anybody learned any thing on this.


Posted By: CTuckerNWIL
Date Posted: 23 Feb 2011 at 9:45am
I wonder if that guy helped develop the Flux Capacitor.

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Posted By: Russ-neia
Date Posted: 23 Feb 2011 at 9:50am
From what I could gather watching the video, the efficiency gains come from balance, thus less weight in motion within the engine in addition to less total vehicle weight; two cycle vs. four cycle (2x as many power strokes); shorter piston travel, thus less drag and also less friction heat loss.  Those would be the big ones.  He also mentions being able to shut down portions of the engine during lower power demand and not loosing the balanced characteristics of the engine.

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Posted By: Charlie (NC)
Date Posted: 23 Feb 2011 at 9:59am
Russ.  I agree with part of that but the concept of shorter piston travel is only partly true.  yes it's a shorter throw for one piston but there are two of them doing the same work that one could do.  The concept of decoupling part of the engine applies only if
you use two of these modular units coupled together.  If you look closely at the video he shows 2 modules bolted together with a clutch between them.  That could be done with any engine setup. 


Posted By: ALinIL
Date Posted: 23 Feb 2011 at 10:33am
I assume this engine will need to the turbo charged.  Reason: fuel charge will have less time to charge the cylinder.  Also lubrication of wrist pins and rods is a real issue.  I have seen the wobble plate design and it appears more promising.  Again the emissions are a issue.


Posted By: Charlie (NC)
Date Posted: 23 Feb 2011 at 10:41am
Al,  I noticed that his model has turbos but I don't understand how even that will work.
Every two stroke diesel I've ever seen, all detroits and the cummins 903, all have superchagers.  It is necessary to get the air charge into the chamber.  Some have turbo's as well for additional power but I don't see how it can run without a blower.


Posted By: Gerald J.
Date Posted: 23 Feb 2011 at 11:29am
Fairbanks-Morse built opposed piston engines beginning in the 30s that were used in WW2 ships and submarines. They were tall. Many a surplus FM ended up in small town power plants where they still are used for backup when the lines go down. FM also built a line of diesel locomotives with those engines. Two cranks, two pistons per cylinder. Gets you the compression needed for diesel with half the piston speed, so they can be long lived. But I wonder about how light weight they would be for an aircraft engine.

I visited a small town power plant where the operators were wanting to sue an oil vender because the rod bearings in their FM engine were only getting 80,000 hours life instead of twice that that they were accustomed to.

But then German WW2 engineering wasn't always about performance. Sometimes it was seriously over designed. I took engineering mechanics from one of those German engineers. He told about freight aircraft with a corrugated skin with a times 10 safety factor after they cut a hole in the side of the fuselage top to bottom and wide enough for loading a grand piano. Flew so slow, that allied aircraft batteries tended to miss by leading it too much. With a non technical dictator, any way to spend money was encouraged so long as it promised to make good use of fuel that they ran low on and they had to invent ways to make fuel without oil wells. Same thing for tires. There was much innovation, but likely much corruption and misdirected experimentation.

Gerald J.



Posted By: Coke-in-MN
Date Posted: 23 Feb 2011 at 11:49am
Norton Villers in Britain got the Wankel design to work in motorcycles and produced quite a few but it would not make US - EPA rules for import as it was a lost oil design. They came up with new type seals for the rotor. a 500 cc designed engine or 1500 cc according to some. The design is now used in drone aircraft after the company quit cycles.

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Posted By: split51
Date Posted: 23 Feb 2011 at 11:56am
 I wonder with the different length of rods (inner and outter) if rod stretch will make the balance change?

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Posted By: TexasAllis
Date Posted: 23 Feb 2011 at 12:13pm
I watched the video twice and picked these items out.  The design started life for use in a helicopter.  The push pull design is the basis for the improved efficiency you have motion in both directions like a recipricating flywheel.  The other improvement is the reduction in weight of the rotating assembly.  The crank is magnesium so you have less mass in a rotating assembly therefore less power loss due to friction.  Lighter metals also dissipate heat quicker.  The engine is turbocharged with electrical assist (I assume a high spped electrical motor).  He did say the challange was oiling the the wrist pins but they did have a solution.  I think with the increased efficiancy 40% and a higher power to weight ratio emmisions might not be a problem


Posted By: Charlie (NC)
Date Posted: 23 Feb 2011 at 12:27pm
TexasAllis, 
 
did you figure out where the increased efficiency is comming from?  Not in terms of power to weight ratio but in terms of power (HP) per unit of fuel burned.  I don't see where that is comming from.  I'll conceed the reduce rolling weight thus less paracitic drag but that is ballanced out by more moving parts per cyl. 


Posted By: TexasAllis
Date Posted: 23 Feb 2011 at 12:39pm
Originally posted by Charlie (NC) Charlie (NC) wrote:

TexasAllis, 
 
did you figure out where the increased efficiency is comming from?  Not in terms of power to weight ratio but in terms of power (HP) per unit of fuel burned.  I don't see where that is comming from.  I'll conceed the reduce rolling weight thus less paracitic drag but that is ballanced out by more moving parts per cyl. 
 
From what I can gather the whole concept is less drag (from mass) and a balanced engine.  The engineer did state that not only was the crank lighter it benefitted from the push pull motion which futher decreased the friction on the crank. 


Posted By: TexasAllis
Date Posted: 23 Feb 2011 at 12:48pm
Two other things I saw since the pistons move half as much the speed of the crank is doubled increasing the power density.  The other was in the valving and if I understand the concept there is no or very little mixing of fresh air/fuel with exaust gasses like you have in a tradtional two stroke.


Posted By: Gerald J.
Date Posted: 23 Feb 2011 at 12:49pm
In most internal combustion engines you achieve increased fuel efficiency with increased combustion temperature. Lubrication of metal parts sets a limit. Some have proposed ceramic engine parts to handle higher combustion temperatures. The pollution problem with increased combustion temperature is the production of nitrous oxide from the nitrogen and oxygen in the air that get combined better the higher the combustion chamber temperature. Tier 4 diesel engines combat that with NOx capture in the exhaust with DEF injection or exhaust gas recirculation.

Gerald J.


Posted By: DMiller
Date Posted: 23 Feb 2011 at 2:14pm
I agree with a previous post, this is a take on the Jumo and the Fairbanks Morse engines of the 40's to series of the 70's, not new technology but a spin on functional and adaptable technology.

Fairbanks still manufactures parts for the opposed piston engines of the WWII marine and late 50's rail type engines, a few are still in service as standby generation engines for power stations.



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