Planetary Gear
AIM: To design a 3D model of a Planetary Gear Assembly and analyse its motion.
THEORY:
A planetary gear mechanism is a gear mechanism consisting of 4 components, namely, sun gear, several planet gears, internal gear or ring gear and carrier that connects planet gears. It has a very complex structure rendering its design or production most difficult; it can realize the high reduction ratio through gears, however, it is a mechanism suited to a reduction mechanism that requires both small size and high performance such as transmission for automobiles.
OBJECTIVES:
- To design a 3D model of Planetary Gear with given specifications.
- To analyse the motion of the assembly with the following cases.
| Case No. | Input | Output | Fixed |
| 1 | Sun Gear | Carrier | Ring Gear |
| 2 | Ring Gear | Carrier | Sun Gear |
| 3 | Sun Gear | Ring Gear | Carrier |
Given Specifications:
Module(m) = 2.5 mm
Ring Gear,
Number of teeth(z_r) = 46
Sun Gear,
Number of teeth(z_s) = 14
Input speed = 200 RPM
Number of planet gear = 4
Pitch Circle Diameter of Ring Gear, `d_r = m * z_r = 2.5*46=115` mm
Pitch Circle Diameter of Sun Gear, `d_s = m*z_s=2.5*14=35` mm
Therefore, Pitch Circle diameter of Planet Gear, `d_p = (d_r-d_s)/2=(115-35)/2=40` mm
Number of teeth in Planet Gear, `z_p = d_p/m = 40/2.5 = 16`
DESIGNING:
1. Planetary Gear Assembly
2. Ring Gear
3. Sun Gear
4. Planet Gear
5. Carrier
CAD Models Link:
https://drive.google.com/drive/folders/1zoh2H5ky4I7IDJrlIC3FKT69KwlODWoT?usp=sharing
MOTION ANALYSIS:
Case 1:
Input: Sun Gear
Output: Carrier
Fixed: Ring Gear
a) Angular Velocity of Input
b) Angular Velocity of Output
Case 2:
Input: Ring Gear
Output: Carrier
Fixed: Sun Gear
a) Angular Velocity of Input
b) Angular Velocity of Output
Case 3:
Input: Sun Gear
Output: Ring Gear
Fixed: Carrier
a) Angular Velocity of Input
b) Angular Velocity of Output
SIMULATION VIDEOS:
Case 1:
Input: Sun Gear
Output: Carrier
Fixed: Ring Gear
Case 2:
Input: Ring Gear
Output: Carrier
Fixed: Sun Gear
Case 3:
Input: Sun Gear
Output: Ring Gear
Fixed: Carrier
CONCLUSION:
As the input speed is same for all the cases, so from the plots of the angular velocity of the output component, we can conclude that case-2 gives maximum output speed which implies that case-2 gives minimum output torque.
And case-1 gives maximum output torque and minimum output angular velocity.