Planetary Gear

Motion Analysis of a Planetary Gear System

Aim:-

To perform Motion Analysis on a Planetary Gear System

Theory:-

An Epicyclic gear train or planetary gear system consists of a system of gears mounted in such a way that the center of one gear revolves around the center of the other. the system usually consists of a sun gear, a ring gear, planetary gears, and a gear carrier.

It has a wide range of applications, from the automatic gearbox of a car to electric screwdrivers.

Procedure:-

For this challenge, a sun gear, a ring gear, 4 planetary gears, and a carrier were designed. As an input, the module and no. of teeth for the ring gear and sun gear were already given. Hence, the no. of teeth and Pitch Circle Diameter for the planetary gear were calculated as given below:-

Module(m) =2.5

PCD(ring gear) = 115mm

PCD(sun gear) = 35mm

Therefore, PCD(Planetry gear) = (115-35)/2 = 40mm

Hence, No, of Teeth(n) => n= PCD/m

therefore n = 16.

Before the gears, an appropriate gear carrier was designed, which is given below:-

And using the calculated value, all the gears were designed and then assembled with the carrier with all the appropriate mates, which would only allow rotation of all the parts along the X-Axis.

The assembly is given below:-

After the assembly was finished, the motion analysis was carried out for three different scenarios. The input velocity = 200 RPM.

With this input, the output angular velocity was plotted on a graph.

The motion analysis for carried out for 1 sec, for each scenario.

Result:-

1. Scenario 1:

Input = Sun Gear

Output = Carrier

Fixed = Ring Gear

2. Scenario 2:-

Input = Ring Gear

Output = Carrier

Fixed = Sun Gear

3. Scenario 3:-

Input = Sun Gear

Output = Ring Gear

Fixed = Carrier

Observation:-

1. In the first case, the sun gear causes the planetary gears to move, but just for an instant, then the motion becomes stationary due to universal gear stationary.

2. In the second case, the ring gear causes a very high velocity of the planetary gears, but then again it becomes stationary, resulting in a very high angular velocity compared to the first case.

3. In the third case, the motion is constant throughout with just a little variation.