Fun with CAD or another example of someone with more CAD skills than real life practical experience.
How do you oil those downward facing pistons?
How much power loss does reversing that large piston assembly cause?
How would you ensure the block and piston assembly both expand at the same rate so the piston stays centered in the bore?
How could you even manufacture the thing given typical machining tolerances?
And these are the big problem I thought of with just one look at that thing. Maybe we should make a game of finding all the weaknesses in these CAD engines?
Obviously not lower manufacturing cost.?
==>Please explain.
I don't see a possibility for less friction.
==> There is no explosion-force hitting the pistons against the cilinderwalls. No friction, no wear.
How do you oil those downward facing pistons?
==> Study Junkers or Commer if you rotate the engine 90 degrees.
How could you even manufacture the thing given typical machining tolerances?
==> Has been done for the Wolff-patent recently.
How would you ensure the block and piston assembly both expand at the same rate so the piston stays centered in the bore?
==> these are wet cylinders
... but there seems to be a lot more cylinder block.
Compare the volumes of the cylinder en pistons with the volumes of all the mechanical parts to convert the thermal energy in a rotatable mechanical energy of an opposed piston Junkers, a opposed piston Commer ( TS3), of any other single piston four-stroke with valves.
Fun with CAD or another example of someone with more CAD skills than real life practical experience.
==> you are so funny for an electricien.
Sorry couldn't help it.
Build one and make it run and it's superior to all other working engines. Then you'll have the last laugh.
You've got pistons on both sides of the block. You're showing them left and right but suggesting run them top and bottom. Top and bottom leave the bottom ones with the middle of the bore lower than the starts of the bore meaning oil that gets in the cylinder will not drain out. The only way I see around this oiling problem is to stand it on end.
You've got extra pivots and links and more mass you are reversing with each piston stroke compared to a typical production engine. So, why will this design have lower losses than current production engines? Trading a little piston friction for more bearing friction and more inertia losses due to changing the direction of moving mass isn't a win.
I have a company myself. We develop and build machines, 25 years already.
My company is "perhaps fun with CAD or another example of someone with more CAD skills than real life practical experience-as you wrote."
The second generation engine is being build. This one is open source as a warm-up.
Still haven't studied Junkers or the Napier-Deltic or the Rootes Commer TS3 , haven't you. Doesnt matter in what angle the cilinders are. Google is waiting for you.
There is no litle pistonfriction, there is NO piston friction except for the seals ofcourse. Pistons and beams are fixed and therefore not hitting the cylinderwalls. Ceramic producers will love this. I prefere greasing joints.Everybody does.
I thought this was a forum for engineers, my mistake.
Your pistons have skirts. Why waste the metal if they don't touch anything.
You also have 3 cranks and a gear drive system.
Some of the pistons will retain oil. Not an insurmountable problem, but far from ideal
By the way this forum is for engineers who behave in a professional manner. Spitting the dummy when someone questions your statements of alleged fact is unacceptable conduct, as is promoting snake oil. At this stage you are borderline on both counts.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
How do you machine a toroidal cylinder bore with acceptable accuracy and surface finish to allow proper piston ring seal? I'm not saying it can't be done - just that I haven't seen how it can be done.
Even piston rings are normally designed to work in cylindrical cylinders, not toroidal cylinders. The local shape of the piston rings has to match the curvature of the "cylinder" so piston ring orientation would have to be maintained. Not impossible, just another thing to think about. I'm not sure how you would make piston rings with a locally convex shape on one side and a locally concave shape on the other side, or whether ignoring this would have any repercussions (I tend to suspect that it would).
Normal cylinder boring and honing equipment only works with cylinders - not toroids.
I should note that Wankel engines also have an odd shape to them - but it is only an odd shape in two dimensions. The apex seals are straight. Those sure had their own set of sealing and oil consumption headaches.
I don't get the claim that there is "no" piston friction. It's got crankshafts and con-rods (which impose a side load on *something*) just like a normal engine. If you solidly guide the pistons so that they are "not hitting the cylinder walls" I guarantee that your engine is going to seize due to differing thermal expansion of the various components unless excessive clearances are provided for ... or you design in some "give".
Piston-porting is always associated with at least *some* loss of lubricant oil out of the ports. Detroit Diesel gave up on piston ported two-strokes largely because of this - and those were "normal" piston and crankshaft engines without the additional headaches of having toroidal cylinders and pistons. Oil out the exhaust or into the combustion chamber is a no-no due to emission regulations.
What combustion system is proposed here? You can't use a normal diesel engine central injector and piston bowl. You can use spark ignition but the spark plug would be at the side of the chamber - not ideal. Again, not saying it can't be done, just that it's another set of things to think about. Poor combustion chamber design means poor efficiency and emissions if you get this wrong.
Opposed-piston concept with this scavenging and combustion concept are possible to achieve using normal cylindrical cylinders and pistons so that you only have to overcome the emission and combustion headaches without additionally having to overcome the difficulty of machining.
I've taken apart and modified and rebuilt my share of "normal" four-stroke piston engines in my own workshop and I have a reasonable understanding of why a good many things in a normal engine are the way they are. Have you done that?
Junkers or the Napier-Deltic or the Rootes Commer TS3
And what is the current production state of these engines?
Your video claims "based on proven opposed piston technology for fuel economy and low emmisions ratings". Where are these current opposed piston engines that have good fuel economy and low emmissions? Remember, production engines are proven designs. Concept engines are not proven designs.
It appears you're claiming the piston and the large pivot arm is one piece. It will be extremely difficult to have a production line machine the block and piston assembly so they mate properly. Then, the expansion rate from the pivot point to the bore center line will be different for the block and for the piston assembly. This will cause the engine to scuff or seize the pistons when the engine temperature changes. You'll likely want to run at most 0.002" clearance between the piston and the bore so there is very little tolerance for error and for varying temperature expansion rates in this assembly.
I believe you will need some form of connecting rod between your piston and that pivoting arm if you expect it to work. You lose your frictionless advantage with a connecting rod. Once you add a connecting rod there is no point in making that extremely difficult to machine toroidal bore.
You posted a link to an CAD engine concept and expected some kind of response. There are a lot of very difficult issues for you to overcome if you expect the design to work. I personally don't feel this CAD design will ever reach production. You don't have to agree with my opinion.
( all his movies or quit interesting conserning toroidal engines ). Have no idea if he honed it.
I myself used for the second enginetype vonkerosion ( don't know if that is the correct english word )in prehardned cylinders, no need for honing.
Wankel in NSU and MAzda : i know the tipseal problems. The pistons in the TROPE are locally cilindrical for the pistonseals with ring fixation for the scavengingports.
I also thought having compressionloss ( convex-concave )but it seems ok. The second engine is having variable compression , because i'm working on HCCI, but that's another item.
Free piston. There is no force ( explosionpressure multiplied with the surface , quite a lot ) slamming the piston against the wall as soon as the piston has left BDP. If you have opened a engine you will noticed the elliptical wear bigger at the top to less at the bottom. fig :
The swingbeam with the fixed pistons have a momentum around the central shaft and are pulling also at that central shaft. All the forces are situated in the rotanting and pivotating ( what a word ) joints.
Loss of lubricant oil out of the ports. Agree. Therefore i prefer quasi vertical cylinders with the cooler inletpistons at the top with reduced lubrification . Pistons being free helps a lot. Not like a Junkers, there is no oil dripping on the back of the upper pistons because these shafts and those cylinders are not vertically lined up, because of the toroidal shape. Eventually leaking oil from the upper pistons can be burnt, bottom leak from the outletpistons is no problem, as you mentioned.
I think that from now on we should talk in these forums only about the positive aspects of these oddball designs, and avoid any discussion of the negatives. Let those who would invest in them learn from experience where the problems lie.
Nobody says it's easy. The easiest stuff is already being thought of. Vonkerosion is a beautifull techniek that wasn't available in the early day's of combustion engines. The sleeves of the cylinders for the swingbeams able to pass by helped the erosionhead going deep to the point were the cilinderwall collisioned with the erosionshaft. Hope you understand what i mean, English is not my native language.
We have had a complete revolution in diesel FIE during my (short, ~25 year) career, plus one or two dead ends. Who's to say that the basic mechanical design that implements an Otto/Diesel cycle can't change?
The garage/CAD inventors should be praised. Unless they start syphoning government funding.
@steve - yeah, but the need for (and benefit of) ever higher injection pressures and better control of timing has been apparent nearly the whole time. Few out there in the engine world are saying "boy if I only had a piston that went in circles, I could meet my customers' and regulators' needs so much better!"
