Planetary Gear

AIM:-

• To generate 3D models
• To assemble The generated models to from the planetary gear
• To do Motion Analysis on the Planetary Gear on the cases given

INTRODUCTION:-

Planetary Gear or Epicyclic gear is a gear system consisting of one or more outer, or planet, gears or pinions, revolving about a central sun gear or sun wheel. Typically, the planet gears are mounted on a movable arm or carrier, which itself may rotate relative to the sun gear. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes with the planet gears. Planetary gears (or epicyclic gears) are typically classified as simple or compound planetary gears. Simple planetary gears have one sun, one ring, one carrier, and one planet set. Compound planetary gears involve one or more of the following three types of structures: meshed-planet (there are at least two more planets in mesh with each other in each planet train), stepped-planet (there exists a shaft connection between two planets in each planet train), and multi-stage structures (the system contains two or more planet sets). Compared to simple planetary gears, compound planetary gears have the advantages of larger reduction ratio, higher torque-to-weight ratio, and more flexible configurations.

The axes of all gears are usually parallel, but for special cases like pencil sharpeners and differentials, they can be placed at an angle, introducing elements of Bevel (see below). Further, the sun, planet carrier and ring axes are usually coaxial.

Epicyclic gearing is also available which consists of a sun, a carrier, and two planets which mesh with each other. One planet meshes with the sun gear, while the second planet meshes with the ring gear. For this case, when the carrier is fixed, the ring gear rotates in the same direction as the sun gear, thus providing a reversal in direction compared to standard epicyclic gearing.

DATA GIVEN:-

Use the following inputs for designing the Planetary Gear

• Ring Gear
  • Module = 2.5 (You must use the metric system in design modeler)
  • Number of teeth = 46
• Sun Gear
  • Number of teeth = 14
• Input Speed of the Gear = 200 rpm.
• Number of planet gears = 4

The dimensions of the carrier depend on the shaft diameter of the planet gear.

With the above input parameters, you are going to run a simulation on the following cases,

Sl.No	Input	Output	Fixed
1	Sun Gear	Carrier	Ring Gear
2	Ring Gear	Carrier	Sun Gear
3	Sun Gear	Ring Gear	Carrier

Calculation:

The diameter of the planet gear

Radius of the ring gear(R_r) = Diameter of the Planet Gear(Dp)+ Radius of the sun gear(Rs)
Dp= R_r-Rs

Therefore, Dp=(115/2)-(35/2)= 40 mm

Number Of Teeths Of Planet Gears

Pitch Diameter,p=m*T

where , m= module

and T= number of teeths

therefore, T=p/m=40/2.5=16

MODELLING :-

For creating the gear go to
Design Library-->Toolbox --> ANSI metric--> Power Transmission-->Gears

For Sun and Planet Gears choose -- spur gear

For Ring Gear choose-- Internal Spur Gear

Ring Gear(Internal Spur Gear)

Sun Gear (Spur Gear)

Planet Gear(Spur Gear)

Carrier

ASSEMBLY:-

• Here I am not using Gear mates .
• The ring, sun and planet gears are assembled in the same position as given below.
• Gears are not being mate with the sketches
• Before undergoing Motion Analysis the Assembly is checked that no teeths of gears overlap or intersect each other.
• The Material for each contact is Steel(Dry)

MOTION ANALYSIS:-

In the Motion Study the contacts are established between all the parts by simply using the contact option and selecting all parts by draging

There are three cases of Motion Analysis:-

Sl.No	Input	Output	Fixed
1	Sun Gear	Carrier	Ring Gear
2	Ring Gear	Carrier	Sun Gear
3	Sun Gear	Ring Gear	Carrier

The input speed of the motor in each case is 200 rpm.

RESULTS:

Case 1: When the Ring gear is fixed

Plot of Angular Velocity Of the Carrier

Case 2: When the Sun Gear is fixed

Plot Of the Angular Velocity of the Carrier

Case 3: When the Carrier is Fixed

Plot Of Angular Velocity of the ring gear

Youtube Link of Animation:-

Case 1:-

https://youtu.be/44M1QcAEgMw

Case 2 :-

https://youtu.be/npw6NB9c8BA

Case 3:-

https://youtu.be/_zi1Io0rf7E

Google drive link

https://drive.google.com/file/d/1-TZY2hSej-cSyMkj2fDacms2a1YbEqsj/view?usp=sharing

CONCLUSION:

• In Case 1- When the input is given (200 rpm) to the sun gear and we carry out the results at the carrier keeping the ring gear fixed. The four planet gear not only rotates about their axis but also forced to roll on the inside of the ring gear since it is fixed . Rolling action can be seen here.
• In Case 2- When the input is given to the ring gear (200 rpm) and the output is obtained from the carrier keeping the sun gear fixed. The Angular Velocity achieved is maximum since the ring gear is large and other gears are comparatively small (as the Velocity Ratio is High). We can see that from the plot too.
• In Case 3 - When the input is given (200 rpm) to the sun gear and we carry out the results as the ring gear is fixed. Here the planet gear rotate only about their axis and transmit motion from the among the gears(sun to ring gear). Since the ring gear is big in diameter the angular velocity achieved is less.
• By using precise contact we can make the plot smoother.