Planetary Gear
PLANETARY GEAR ASSEMBLY IN SOLIDWORKS WITH MOTION ANALYSIS
AIM:
To create the models of a planetary gear assembly and assemble to analyse the motion of the gears in solidworks 2019.
PLANETARY GEAR:
An epicyclic gear train (also known as planetary gear) consists of two gears mounted so that the center of one gear revolves around the center of the other. A carrier connects the centers of the two gears and rotates to carry one gear, called the planet gear or planet pinion, around the other, called the sun gear or sun wheel. The planet and sun gears mesh so that their gears roll without slip. A point on the pitch circle of the planet gear traces an epicycloid curve. In this simplified case, the sun gear is fixed and the planetary gear(s) roll around the sun gear.
An epicyclic gear train can be assembled so the planet gear rolls on the inside of the pitch circle of a fixed, outer gear ring, or ring gear, sometimes called an annular gear. In this case, the curve traced by a point on the pitch circle of the planet is a hypocycloid.
The combination of epicycle gear trains with a planet engaging both a sun gear and a ring gear is called a planetary gear train. In this case, the ring gear is usually fixed and the sun gear is driven.
Epicyclic gears get their name from their earliest application, which was the modelling of the movements of the planets in the heavens. Believing the planets, as everything in the heavens, to be perfect, they could only travel in perfect circles, but their motions as viewed from Earth could not be reconciled with circular motion
HISTORY:
At around 500 BC, the Greeks invented the idea of epicycles, of circles travelling on the circular orbits. With this theory claudius in the almagest in 148 AD was able to predict planetary orbital paths. The mechanism, circa 80 BC, had gearing which was able to approximate the moon's elliptical path through the heavens, and even to correct for the nine-year precession of that path. (The Greeks would have seen it not as elliptical, but rather as epicyclic motion.)
GEAR RATIO:
The gear ratio of an epicyclic gearing system is somewhat non-intuitive, particularly because there are several ways in which an input rotation can be converted into an output rotation. The three basic components of the epicyclic gear are:
- Sun: The central gear
- Carrier: Holds one or more peripheral Planet gears, all of the same size, meshed with the sun gear
- Ring or Annulus: An outer ring with inward-facing teeth that mesh with the planet gear or gears
CALCULATIONS:
COMPONENTS:
SUN GEAR:
PLANETARY GEAR:
CARRIER:
ASSEMBLY:
ANGULAR VELOCITY:
PLANETARY GEAR:
REACTION FORCE B/W GEARS:
GEAR NOMENCLATURE:
CONCLUSION:
Case 1:
When ring gear is fixed, the sun gear is given as input and planetary gears rotate along with the carrier on the ring gear.
Case 2:
When the sun gear is fixed, the carrier along with planetary gears rotate.
Case 3:
All the gears assemblage rotates in planetary assembly.
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