Difference between revisions of "Atomically precise roller gearbearing"

Latest revision as of 10:28, 28 September 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 interdigitation 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, non-roundness, or something else.
And thus ungeared rollers tend to start to slide and consequently self destruct.

Why no lubricants? Because:
The atoms of lubricants are like grave at the nanoscale and
atomically precise surfaces of good gemstone like compounds feature:

• FAPP no wear (no structural irreversibility) and
• low dynamic friction for low sliding speeds – (there is a tiny bit of sliding in rolling gears)

See sections below for details.

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.

See: Examples of diamondoid molecular machine elements

Naming: How about "Countertomic rollerbearings"?

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.
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.

Even "graphene-sheet-lining" could perhaps be an option maybe. See: nanoscale passivation for that.

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

Especially bigger atomically precise gear-bearings have hollow spaces where dirt could find place obstructing motion and leading to damage.
(Note that as these are gearbearings no cages for rollers are needed.)

The assumption is though that atomically precise seals get included
compartmentalizing space and thereby:

• making a PPV possible and
• leaving not a single stray gas molecule in.

As for dirt from hard ionizing radiation splitting it off from AP surfaces:

• This should be covered by system redundancy and
• eventual selfrepair by subcomponent replacement (hot plugging or not).

The smaller the system the less room there is for undetected slight damage.
Either it works or it does not.

On the other hand the bigger the system the more there is space for undetected slight damage.

There is likely a sweet spot at quite small scale with

• very low degradation
• already low friction for higher speeds

Related: Vacuum lockout

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

Related

• Superlubricity
• Infinitesimal bearings
• Mesoscale friction

External links

• Gear bearing
• Tapered roller bearing
• Needle roller bearing
• Category:Rolling-element_bearings

Tapered roller bearing can be made tapered into gearbearings.
Adding a soft herringbone tooth trajectory can prevent rollers from sliding out despite compressive force.
In tapered tapered roller gearbearings backlash can be elegantly brought to zero by applying some very axial pretension.