“Orbitless drive”的意思、由来-开放百科全书

An orbitless drive is a patented^[1] epicyclic drive which scales the speed and torque of an input shaft by a ratio. It is sufficiently efficient^[2] to be back-driveable, and may be used as speed reducers or overdrive mechanisms.

Like a planetary drive, the input shaft drives a central sun gear which in turn, drives a group of planet gears that ride on a planet carrier. Unlike a planetary drive, the planets do not engage a ring (orbit) gear. Instead, a second carrier which is misaligned with respect to the first carrier prevent the planets from rotating. They circulate around the sun at a fixed orientation while transferring mechanical energy between the sun and carrier.

Theory of operation

The reduction ratio (i) of the orbitless drive with a pinion sun is obtained from the following formula, where Zs is the number of sun gear teeth, Zp is the number of planet gear teeth, the sun is the input, and the carrier is the output^[3]. The resulting ratio is half the ratio obtained from a planetary gear using similar pinions.

When the sun is a ring gear, the reduction ratio is as follows^[3]. Since Zs must be larger than Zp, the ratio is always positive and less than unity so it acts as an overdrive. Like any overdrive, it may be used as a reducer by interchanging the roles of the input and output shafts. The same ratio results if the sun is a pinion and is engaged with the planets through a non-direction-reversing transmission path such as a belt, a chain, or an idler gear. In this case, a negative or very high overdrive ratio is possible.

Properties

Gearing applications are too diverse to associate technological advantages without context. For example, high efficiency is mandatory in automotive and power generation applications, but undesirable in actuators and adjustment mechanisms which must hold a desired position under extreme load. The three low-ratio gearing configurations each have distinguishing properties which motivate their usage.

Parallel-Axis

Planetary

Orbitless

Compared to a planetary drive, the absence of a ring gear and the inclusion of a second carrier offset one another in terms of cost and complexity. Load capacity is generally greater than a parallel axis drive due to load sharing, but less than a planetary drive due to tighter space constraints on planet bearings. Similar to a planetary drive, compound planets may be used to achieve very high reduction ratios^[4]. Similar to a parallel-axis drive, the absence of internal teeth enables the use of belts and chains.

A unique property of orbitless geometry is that none of the planet axes are required to be in the centre of the planet. Both may be displaced to make room for larger planet bearings.

History

The concept of the orbitless drive was initially developed by Canadian engineer Leo Stocco in 2014 and the patent rights are held by Canadian company Orbitless Drives Inc.^[5] located in Vancouver BC.

See also

References

1. ^US Patent #9,970,509
2. ^{{Cite journal|last=Stocco|first=Leo|date=2017|title=A New Standard of Epicyclic Efficiency - A Practical Comparison of Planetary and Orbitless Gear-Heads|url=https://link.springer.com/article/10.1007/s10010-017-0235-z|journal=Forschung im Ingenieurwesen|volume=Vol 81, Issue 2-3|pages=153-161|via=}}
3. ^¹{{Cite journal|last=Stocco|first=Leo|date=2016|title=The Orbitless Drive|url=http://ece.ubc.ca/~leos/pdf/ref/IMECE2016-orbitless.pdf|journal=ASME International Mechanical Engineering Congress & Exposition|volume=|pages=|via=}}
4. ^{{Cite journal|last=Stocco|first=Leo|date=2016|title=The Coupled Orbitless Drive|url=http://ece.ubc.ca/~leos/pdf/ref/IMECE2016-65284-Corrected.pdf|journal=ASME International Mechanical Engineering Congress & Exposition.|volume=|pages=|via=}}
5. ^{{Cite web|url=http://orbitless.com/|title=Orbitless Drives|last=|first=|date=|website=|archive-url=|archive-date=|dead-url=|access-date=}}