Duke Engines' compact, lightweight valveless axial engine
1–10 of 58 posts
Re: Duke Engines' compact, lightweight valveless axial engine
#2Looks interesting, but I'm guessing there is a lot of stress on the recipricator mechanism that the pushrods connect to, pushing against an incline to cause the output shaft to rotate.
Re: Duke Engines' compact, lightweight valveless axial engine
#3Looks interesting, but I'm guessing there is a lot of stress on the recipricator mechanism that the pushrods connect to, pushing against an incline to cause the output shaft to rotate.
I agree, but in a typical combustion engine there is also a comparable amount of stress on connecting rod bearings and the typical design of a crankshaft also puts a lot of side-force on the entire piston and rod assembly.
I can't find enough information on their "reciprocator" to see how it differs from other swash/wobble-plate based axial engine designs.
Re: Duke Engines' compact, lightweight valveless axial engine
#4Looks interesting, but I'm guessing there is a lot of stress on the recipricator mechanism that the pushrods connect to, pushing against an incline to cause the output shaft to rotate.
Yeah, I'd be interested in seeing a life expectancy for these. If they're really all that's being said, I'm hopeful for the future.
Re: Duke Engines' compact, lightweight valveless axial engine
#5Looks interesting, but I'm guessing there is a lot of stress on the recipricator mechanism that the pushrods connect to, pushing against an incline to cause the output shaft to rotate.
It can be as beefy as it needs to be. There is no constraint there to limit the design.
It is actually an extremely flexible concept from what I can tell. Need a longer stroke? Add more angle to wobbler. Need more Torque? Expand the wobbler diameter.
Re: Duke Engines' compact, lightweight valveless axial engine
#6No mention of meeting fuel economy and emissions requirements. Both of those are big topics that engine builders have to consider, with the 35mpg fleet-wide average that cars sold in the US must meet in about a decade. Having grown up in an age filled with car exhaust from carburated engines, I don't miss it a bit -- I like having clean air.
One of the comments to the article mentioned the difficulty in keeping high-pressure seals working. It was in conjunction with Wankel rotary engines, which have always had problems with the rotor tip seals leaking (ask any Mazda RX owner...) This engine has the same problem on the intake/exhaust end, as the piston carrier rotates past the openings.
Re: Duke Engines' compact, lightweight valveless axial engine
#7No mention of meeting fuel economy and emissions requirements. Both of those are big topics that engine builders have to consider, with the 35mpg fleet-wide average that cars sold in the US must meet in about a decade. Having grown up in an age filled with car exhaust from carburated engines, I don't miss it a bit -- I like having clean air. One of the comments to the article mentioned the difficulty in keeping high-…
Thank you. I'd wondered how this would compare to a rotary engine. It's interesting how enthusiastic the rotary-engine crowd is, since my takeaway was always "well if it's so much better why isn't it more common".
Re: Duke Engines' compact, lightweight valveless axial engine
#8Looks interesting, but I'm guessing there is a lot of stress on the recipricator mechanism that the pushrods connect to, pushing against an incline to cause the output shaft to rotate.
It can be as beefy as it needs to be. There is no constraint there to limit the design. It is actually an extremely flexible concept from what I can tell. Need a longer stroke? Add more angle to wobbler. Need more Torque? Expand the wobbler diameter.
There is a limit on the available angle that can be "wobbled". Once you exceed ~20 degrees IIRC, the displacements perpendicular to the stroke start causing problems.
I think the more interesting interaction is between the number of pistons and the size of the pistons.
Re: Duke Engines' compact, lightweight valveless axial engine
#9The money quote, for the TL;DR crowd:
"Duke Engines' 3-liter, five cylinder test mule is already making a healthy 215 horsepower and 250 lb-ft of torque at 4,500rpm – slightly outperforming two conventional 3 liter reference engines that weigh nearly 20 percent more and are nearly three times as big for shipping purposes. With an innovative valveless ported design, the Duke engine appears to be on track to deliver superior performance, higher compression and increased efficiency in an extremely compact and lightweight package with far fewer moving parts than conventional engines."
Re: Duke Engines' compact, lightweight valveless axial engine
#10No mention of meeting fuel economy and emissions requirements. Both of those are big topics that engine builders have to consider, with the 35mpg fleet-wide average that cars sold in the US must meet in about a decade. Having grown up in an age filled with car exhaust from carburated engines, I don't miss it a bit -- I like having clean air. One of the comments to the article mentioned the difficulty in keeping high-…
Thank you. I'd wondered how this would compare to a rotary engine. It's interesting how enthusiastic the rotary-engine crowd is, since my takeaway was always "well if it's so much better why isn't it more common".
> "well if (rotaries are) so much better why isn't it more common".
That's a complicated question with a complicated answer, but it basically boils down to there having been hundreds of billions of dollars (trillions?) spent on R&D for traditional (pison, conrod, crank, block) engines, while only a tiny amount has been spent on R&D for rotaries and other "different" designs.