Motion Analysis of Planetary Gear Mechanism

Aim: To perform Motion Analysis of planetary gear mechanism

Objectives:

1. To create cad model of sun gear, planetary gear and ring gear and assemble them.
2. To perform motion study and extract useful information from motion study
3. To do analysis of different result for different condition

Theoretical background:

1. Introduction:

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 circle 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.

1.Problem statement:

Ring Gear:

Module = 2.5

Number of teeth = 46

https://drive.google.com/file/d/17bNNbUvSMMBv8d6fpltkyqEmNMJaTXKI/view?usp=sharing

Sun Gear:

Number of teeth = 14

Module = 2.5

https://drive.google.com/file/d/1ZkEnxNoc-3oTt9NwRwGOjw_IU5ggCcns/view?usp=sharing

Planet gear:

To calculate pitch circle diameter and no of teeth of planet gear

We know Module of Gear(M) = 2.5

From above diagram

From above equation

Diameter of planet gear = 40 mm

No. of teeth = 16

Number of planet gears = 4

https://drive.google.com/file/d/1UuZwThuY5BIkLfVRiMnwTufv5wXeUIK4/view?usp=sharing

Carrier of Assembly:

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

https://drive.google.com/file/d/19L_4EZfnbKeq746IUAyybbQ-15uOCB1e/view?usp=sharing

Assembly of Planetary gear mechanism:

https://drive.google.com/file/d/1S-cAxpaLnBJtCypiVU-9m4pvuFBW4FJf/view?usp=sharing

In problem we have given

Input Speed of the Gear = 200 rpm.

We need to do analysis of three different cases:

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

Procedure followed:

1] Use design library to make cad model of Gear

2] Use ANSI Metric from tool box to make cad model of gear

3] Assemble them with proper mate and without using gear mate

4] perform Motion analysis for different set of conditions

5] Extract some useful data out of motion analysis

6] Do analysis of result

Problem encountered:

1] while doing motion analysis do not give unnecessary solid contact and mates it will take large time to get solution.

2] while doing motion analysis don’t fix two part at time

Plots:

1. Case-I

Input: Sun gear

Output: Carrier

Fixed gear: Ring gear

2. Case-II

Input: Ring gear

Output: Carrier

Fixed gear: Sun gear

3. Case-III

Input: Sun gear

Output: Ring gear

Fixed gear: Carrier

Conclusion:

1] Case-I planet gear rotates about its own axis and also rolls on ring gear and Angular velocity of Carrier has increased first and then fluctuating within range.

2] Case-II Angular velocity of carrier is changing frequently and at some point, it has reached maximum of all three cases.

3] Case-III Angular velocity of ring gear has increased at start then it is fluctuating within some range.

Result: Motion Analysis of Planetary gear mechanism has been done successfully.