was thinking about how rotors apex seals wear due to being drug accrost the face of the housing. I think it would be cool to somehow replace apex seals all-together with a long roller bearing that would spin in the apex of the rotor. you would have to completely re-design the rotor itself ofcorse.. im no engineer yet. but i was just curious if im the only one who thought of this. and i want to know other peoples thoughts on replacing this weak point.. the rotarys weak point.

 

I'm pretty sure thats been discussed before. You have to think of the combustion forces that it would be placed under. Something like that would easily let combustion gases by.

 

it would involve many many more small fragile moving parts, are you sure something like that would even seal?

 

nope

 

The current design is proven to last over 100k miles (in stock form.. )

There are a bunch of other designs that nsu tried out one of which used an idea similar to what you describe, however it was scraped and the proven method of apex sealing is the seal design you see today

 

Mine lasted 215k with lots of track time. I know there was someone here with something like 380k and still running.

 

i know they can last awhile trust me im aware. but wouldnt we all like an inovation that allowed our engines to last 100k miles under 20 pounds of boost and arround 10 times more detination rezistant? im not saying my idea is practical or anything but theres always room for ideas and improvement

 

As an engineer...

Here is my 15 second rendition of the fundamental friction issue with your proposal.

 

even if it worked, after some time carbon would foul the roller and it would.. stop rolling, ending up looking like the apex seals we have now. .

 

i see what your saying the pressure has room to get under the bearing and lift it and let pressure bypass the bearing.. maybe doing a bearing would eliminate having to have springs all together that way the bearing is in a fixed position and has no room to be depressed by underflowing pressure. i would imagine that wouldnt be possible because if the bearing didnt move in and out, it wouldnt make contact all the way around the housing on all points?

 

lol good point your probly right karack

 

the other side to the concept is the speed at which the bearing would be rolling, i would estimate it at about 100,000RPM at least depending on the size of the roller, the friction and drag alone would wind up keeping the bearing from having a constant speed against the surface, it likely would be slipping quite a bit.

 

18 views so far 11 replies and i just posted it lol i didn't know the idea in the back of my head was THAT idiotic gee j/k

 

As if things don't spin fast enough in our engine already...

 

dont let this stop you from thinking. Things like this are what make amazing new innovations possible. Keep bouncing ideas off each other and eventually something will stick.
I still feel that lightening the rotating mass would be the best innovation for the internals. With all the improvements in materials made in the past 4 decades you would think it would be time to move to a new material.

 

A solution for that, maybe to impove on sealing, would be to make an imprint in the rotor housing that would fit the Exact size of the roller, so the roller slides into the imprint, seals perfectly, that state happens, and it moves onto the next one.


Any thoughts on that?

 

yes i heard mazda is experimenting on an all aluminum block rotary. not sure about the internals. i often wounder what they could do to lighten the e-shaft. maybe keep it the same material but make it hollow like a drifeshaft. the rotors themselves on the rx8 are prety light in comparison to ours. i dont know much about the rx8 rotors as to how they accomplished that, are then aluminum in places?

 

what about like a rubber track and a matching rubber spot on the bearing to help with slipping... or even a gear? i dunno. its getting complicated fast...

 

sometimes complexity isnt a disadvantage, just because soemthign is complex doesnt mean it will break easier just over engineer it lol

 

it was my understanding that they are not much lighter like 1 pound. All aluminum block is done,RB made the irons out of aluminum, you can pick them up for like 3K for the set. But that is to help keep xpansion the same between all housings. My thought was for more of an innovative material that may drop the weight to 5 pounds even if it was for race engines only,with a life of only a few thousand miles before the seal grooves get out of tolerence it may be worth the cash to a small market. It is not a large enough market to make the R&D worth it at this time so maybe someday it will happen.

 

The oil injectors do a barely adequate job of keeping a film of oil between the apex seal and the rotor housing at best....and my guess is that a premix would still not keep a roller seal setup very well lubed. As Karack said, the roller rpm would be a big problem. Might as well forget about putting anything else rubber in the combustion environment of a rotary....we all know how well the soft seals hold up under boost as it is.

 

What is your proof of this?

Anyway, on the original topic, most problems have already been discussed. One that has not been mentioned is that any rotating seal (and it's race as well) would have to be made of HARD material to not quickly wear out due to the heat and speed. Hard material will not seal very well aginst the hard chrome surface of the housing.

And then there's still the issue of sealing off the ends.

Remember, Mazda basically tried every single material available at the time when they were developing their seals. It nearly bankrupted the company (or so the story goes).