Workable opposed piston engines

[soccerballtux]

At the end of a cycle in a traditional ICE, the bottom of the piston makes contact with oil and draws a film with it up the sides of the cylinder. Where does oil lubrication come from in this design?

 

[soccerballtux]

unrelated, I'm happy to see more manufacturers looking at cylinder cycling/disabling when cruising on the highway. It would be great to get an 8 cylinder monstrosity and be able to get 30mpg when cruising on the highway.

 

[Fern]

At the end of a cycle in a traditional ICE, the bottom of the piston makes contact with oil and draws a film with it up the sides of the cylinder. Where does oil lubrication come from in this design?

Good question.

I can't say I have a good grasp on the mechanics needed here, but seems to me more parts are required to unify the power from both sides, meaning more friction and less efficiency.

Fern

 

[bfdd]

Good question.

I can't say I have a good grasp on the mechanics needed here, but seems to me more parts are required to unify the power from both sides, meaning more friction and less efficiency.

Fern

doesn't seem like there's all that many moving parts compared to a regular ice tbh.

 

[ch33zw1z]

Pretty to look at, lets see it in action.

 

[nonlnear]

At the end of a cycle in a traditional ICE, the bottom of the piston makes contact with oil and draws a film with it up the sides of the cylinder. Where does oil lubrication come from in this design?

(Assuming they can make a working prototype) there isn't as much need for lubrication because there is no side loading on the pistons. Yes there will be a need for some lubrication provision, but it's not clear that it will need the same volume of oil on the walls as one is used to designing for with a conventional piston engine. Who knows, they might be able to provide sufficient lubrication with a drip system. Seriously, until they build the thing, who knows?

 

[xj0hnx]

At the end of a cycle in a traditional ICE, the bottom of the piston makes contact with oil and draws a film with it up the sides of the cylinder. Where does oil lubrication come from in this design?

Probably oiler squirters.

 

[dmcowen674]

Sounds like something the oil industry will do its best to delay as long as possible.

This

We will never see it

 

[werepossum]

(Assuming they can make a working prototype) there isn't as much need for lubrication because there is no side loading on the pistons. Yes there will be a need for some lubrication provision, but it's not clear that it will need the same volume of oil on the walls as one is used to designing for with a conventional piston engine. Who knows, they might be able to provide sufficient lubrication with a drip system. Seriously, until they build the thing, who knows?

This is a big part of it, but opposing that is the greater density which in turn means greater heat concentration. The primary way of lubricating such engines would be pressurized oil injection. Oil would be injected into the crankshaft main journals, enter the connecting rods through the pressurized rod journals, rise up the connecting rods, and be expressed into and through the piston to directly lubricate the rings. Oil would also be pumped through the block around the cylinders to carry away heat - being an extrusion makes this simpler than with conventional engines. Lower output versions would require comparatively little lubrication. Very high output/high concentration models such as the single stroke four piston/cylinder are currently also air-cooled by compressing air and forcing it through the pistons, but I'd be surprised if that lasts into production (if production ever happens.) The biggest purpose of engine oil isn't lubricating so much as carrying heat away from the parts that generate it, air is a poor heat transfer medium at best, and the required air journals greatly complicate the design.

 

[iGas]

The big question is how many crankshafts the engine will have, and how many more moving parts?

Look like 2 crankshafts at the moment.

I would like to see the true "energy" out put after moving parts and heat lost compare to the traditional engine.

What about durability, and will it stand up to variable rpm?

 

[nonameo]

Ah, when I read about this it made me think of subaru, but I guess this is a bit different isn't it?

 

[KlokWyze]

Cool thread. My friend actually just bought a 2005 Mazda RX-8 and it has a rotary engine. It's certainly more efficient in terms of size & power. 1.3 liter engine that puts out about 230-ish HP.

Short video demonstration

 

[werepossum]

The big question is how many crankshafts the engine will have, and how many more moving parts?

Look like 2 crankshafts at the moment.

I would like to see the true "energy" out put after moving parts and heat lost compare to the traditional engine.

What about durability, and will it stand up to variable rpm?

Some early opposed piston/common cylinder models had a single crankshaft, which caused side loading in excess of conventional engines and weren't practical at all. Probably all these engines will have two crankshafts; you can easily add gearing to provide a single output shaft, but I doubt you'd see any significant advantage other than maybe weight once you account for the extra gear friction losses.

Ah, when I read about this it made me think of subaru, but I guess this is a bit different isn't it?

Very different except for the principle that opposed reciprocating mass motion cancels out a lot of the vibrations.

Cool thread. My friend actually just bought a 2005 Mazda RX-8 and it has a rotary engine. It's certainly more efficient in terms of size & power. 1.3 liter engine that puts out about 230-ish HP.

Short video demonstration

Wankels are cool too. I suspect that with modern materials, rotary engines could be a lot more practical and longer-lived than the RX-8 models. Another competitor would be the gas turbine; it has some specific disadvantages in addition to advantages, but if it's purpose is to generate electricity to drive motors and/or charge batteries simultaneously then a lot of those disadvantages disappear. Gas turbine generators for example don't spin up fast enough for life safety purposes, but are miniscule compared to equivalent I.C.-powered generators.

And for military vehicles, all rotary engines have the advantage of generating fewer low frequency noises, which are hard to attenuate.

 

[Lithium381]

wow interesting concept, can't wait for new generations of engines....

 

[Mark R]

Opposed-piston engines were used for years, starting in 1950, in British diesel locomotives.

These engines were the Napier Deltic design. In this design, the cylinder banks were arranged in a triangular (or Delta) shape, with a crank at each vertex, and the cylinder bores on the edges.

This engine was extraordinarily smooth, and was widely used by the Navy for minesweeper vessels.

 

[nonameo]

Cool thread. My friend actually just bought a 2005 Mazda RX-8 and it has a rotary engine. It's certainly more efficient in terms of size & power. 1.3 liter engine that puts out about 230-ish HP.

Short video demonstration

I have owned 2 rotary powered vehicles. Rotaries are nice because for the space the engine takes up in the engine bay, you can get some nice power. However, you can't directly compare rotary displacement to piston engine displacement. For an explanation, check this out:

http://www.rx7.com/techarticles_displacement.html

IMO rotaries find their best use in the racing department, where fuel consumption and noise aren't a concern and you can do a nice peripheral port and let that thing scream at high RPMs.

porting:

http://www.mazdarotary.net/porting.htm

I know its a little OT but since we're talking about engines I figured I'd mention it

 

[piasabird]

Untill it is tested at daytona or in a production vehicle with lots of miles, it is hard to say what any engine can do. Some modern engines did not show all the real problems until they were put into production. I think Ford had a big loser in truck engines that runs fine until you need to change the spark plugs.

 

[werepossum]

Opposed-piston engines were used for years, starting in 1950, in British diesel locomotives.

These engines were the Napier Deltic design. In this design, the cylinder banks were arranged in a triangular (or Delta) shape, with a crank at each vertex, and the cylinder bores on the edges.

This engine was extraordinarily smooth, and was widely used by the Navy for minesweeper vessels.

Agreed. Problem has historically been that such engines were very difficult to design, sensitive to inclination, and maintenance-intensive, since with a failed ring or asymmetrical carbon build-up the engine can rapidly beat itself to death. For the vast majority of applications, similar smoothness with better reliability and robustness could be obtained using conventional I.C. engines with opposed cylinders and a common crankshaft (like Subaru or Volkswagen) or radial engines (like the Wright and BMW airplane engines of WWII.) This design is the first really significant improvement I've seen in that they have forgone a common crankshaft in favor of very low side thrust (something Volkswagen and BMW will tell you is not an issue with proper machining - try finding a ridge reamer in Germany!) as well as improving the block design to use extrusions.

Of course, these things also limit the engine to those applications where dual output shafts which are not individually controllable can be a feature rather than something to work around. This thing may not be at all practical for mass production even with the effort toward manufacturing practicality. As I see it, it's niche (high output, compact, low weight) has strong competition from small turbocharged direct injection diesels, Wankel-type rotary engines, and gas turbines. But even if it never goes into production, it's uber cool technology.