Difference between revisions of "Atomically precise roller gearbearing"
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Revision as of 12:09, 11 August 2022
Up: Atomically precise bearings
Atomically precise roller gearbearings are bearings with:
- all surfaces being atomically precise and nonreactive (See: nanoscale passivation)
- roller having gear teeth
- dry running – no lubricants
- atomically tight seals
Why not smooth ungeared rollers? Because:
- low resistance against slipping at the nanoscale may cause hard to predict behavior including sliding of rollers.
- no slipping implies interdigitation at the nanoscale and atomically precise interdifitation implies well defined gears
As a side-note: FFF printed bearings also typically work better as gearbearings.
There the reason is that static friction from material-to-material contact is often lower than forces from hookups on printing-inaccuracies like layerchange-blobs, nonroundness, or something else.
And thus ungeared rollers tend to start to slide and consequently self destruct.
Contents
Types
Shapecomplementary atomic teeth gearbearings
Here protruding atoms act as gear teeth addenda and
the trough spaces between act as gear teeth dedenda.
- For cylindrical rollers atoms can be arranged in rows or spirals.
- For conical rollers rows or spirals are not an option as the teeth
continuously and slowly would vary in width which atoms can't.
Some prototypes have been modeled theoretically via means of molecular dynamics modelling.
Superlubricating toothflank gearbearings
Conventional gear teeth profiles are approximated. Cycloid, Evolvent, or other.
Very much conventional gears.
When tooth flanks contact then ideally the atomic bumpyness is as imcommensurable as possible. <bt> Such design leads to superlubricity when tooth-flanks rub more or less forcefully along each other ([*|accidentally suggestive]).
Flank shapes can be approximated by strained shell structures.
Where the outer surface is undisturbed lattice and the inner structure
contains intentional defects similar to the principle of Kaehler brackets.
Getting smooth flanks near enough the mathematic ideal such that
the elastic surface-surface interactions can do the rest works better for bigger gears.
Smaller gears (filling the size gap down to Shapecomplementary atomic teeth gearbearings)
By only crudely approximating shape Kaehler bracket style might
get a bit rough in operation meaning large remaining energy barriers during rotation.
Thus they may be less desirable.
Naming: How about "SuToFlaGe bearings"?
Lower friction at higher speeds
While Atomically precise slide bearings can be
very compact and feature extremely low energetic friction losses for very small speeds
losses are not low for moderate speeds and it gets really bad for high speeds.
But looking how efficient macroscale bearings can be for high speeds this is unsatisfactory.
As roller (gear)bearings are a direct analogy they should be able to allow significantly lower losses at higher speeds.
This works by two effects:
- Lower sliding speeds – teeth in gears still slide but much slower than speeds in a sliding bearing
- lower contact area – there's no point contact because of elastic deformation
Note that:
- the lower contact area reduces load bearing capacity
- the (necessarily atomically tight) seal still contributes to sliding friction – quadratic
- contact area reduction only linear
At the cost of high design effort going for infinitesimal bearings reduces losses quite a bit.
Roller gearbearing based infinitesimal bearings will likely be much preferrable over sliding infiniresimal bearings.
Infinitesimal bearings need rollers to distribute speeds equally anyway.
See main pages: Friction in gem-gum technology, Friction
Wear
Since surfaces are assumed atomically precise after production and materials are assumed extremely hard. Typically Mohs 8 and above.
The only modes of damage are:
- via sufficiently ionizing radiation (and degradation from there) – a hit can be quite the "nano-nuke"
"sufficiently ionizing" means UV may not be high energy enough - significant thermal overload (melting)
- significant mechanical overload (total crush)
- dissolution by very aggressive chemicals - if the chemical manages to breach the seal
- a combination of the above
If properly built with atomically tight seals then potentially damaging nanoscale dirt can't get in.
Sealing & dirt
Relation to atomically precise gears
Gears are basically the same. Geometry of loads is typically different which may reglect in specific designs.
Tooth profiles
For gearbearings (full) cycloid profiles seem good?
- Cycloid gears have flank lower sliding speeds than evolvent gears and are known for their low friction properties.
- The varying pressure angle of cycloid flanks is less problematic in the absence of tangential loads as present in gear-trains
helical tooth trajectories can further help there - Full cycloid profile gears can be pressed together reducing backlash to zero by pre-tension.
Evlovent flanks need high pressure angles for that and incur more sliding speed
Conductive roller gearbearings
For motors and generators conductive rollers should give
notably lower losses than using tunnelling contacts.
See: Electromechanical energy conversion
