Planetary Gear

Aim: Motion analysis of Planetary gear using Solidworks Multi Body Dynamics.

Theory: 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 pitch circles 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.

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. In this case, the ring gear is usually fixed and the sun gear is driven.

Model: Components used in analysis are:

1. 4 Planetary Gear
2. 1 Sun Gear
3. 1 Ring Gear
4. 1 Carrier

1. Sun Gear

2. Planetary Gear

3. Ring Gear

4. Carrier

4. Assembly

Google Drive link for the CAD model

https://drive.google.com/open?id=1FCtTKiGuJfNHwARTYeLqFqadUx-wO6e2

https://drive.google.com/open?id=1RNFYveZGMYoxBf0niqSdrfFFVInN6Q_Q

Calculation:

Gear rpm = 200

Ring Gear:

Module = 2.5;

Number of Teeth = 46;

`m=d_p/t_p`

`d_p`= 2.5*46 = 115mm

Sun Gear:

Module = 2.5;

Number of Teeth = 14;

`m=d_s/t_s`

`d_s`= 2.5*14 = 35mm

Planetary Gear:

Module = 2.5;

`d_r=2*d_p+d_s`

`m*t_r=2*m*t_p+m*t_s`

`t_p`= 2.5*16 = 40mm

Procedure:

1. For the Planetary Gear analysis, We will first open the Solidworks part modelling to make the 3D CAD model of the carrier in which the planetary gears and Sun Gear are fitted.
2. Then We will go for Solidworks assembly to start assembling the CAD model for motion analysis.
3. Now we will go to design library and go for ANSI metric and then power transmission and then gears and then we will select the Spur Gears and define them and then the Internal Spur Gears for the Ring Gears.
4. The process of dragging and defining the Spur Gear will be repeated 5 times as one for the Sun Gear and four times for the Planetary Gears.
5. The process of dragging Internal Spur Gear is repeated one time and then we will define its specification.
6. Then we will define the Gear relation and we will make them constraint such that they can only rotate about their axis.
7. Now since constraining had been done we will go for motion analysis.
8. We will click on Solidworks motion to go for motion analysis.
9. Now we will define the contact between the gears and carriers.
10. Now using the motor option we will define the input as an input with 200rpm.
11. Now we will hit on calculate to calculate and then using results and plots we can get our desired results and plots.

Results:

Case 1)

Ring Gear fixed

Plot of Angular Velocity vs. Time

Case 2)

Sun Gear fixed

Plot of Angular Velocity vs. Time

Case 3)

Carrier fixed

Plot of Angular Velocity vs. Time

Conclusion:

1. In Case 1 Sun Gear is provided with input as a motor of constant rpm 200 and the output made is Carrier while the Ring Gear is fixed.
2. In Case 2 Ring Gear is provided with input as a motor of 200 rpm and the output made is Carrier and the Sun Gear is fixed in this case.
3. In Case 3 Sun Gear is made as input as a motor of constant 200rpm while the output is Ring Gear and Carrier is fixed.

From all the three cases we can conclude that highest angular velocity obtained is in case 2 while if we consider a steady angular velocity then case 3 can be considered.

Link for the simulation:

Case 1) https://youtu.be/ib43lzlQPOY

Case 2) https://youtu.be/1U554hYYc7Q

Case 3) https://youtu.be/mzFhL290Pgo