Planetary Gear

PROJECT REPORT

PLANETRY GEAR ASSEMBLY

INTRODUCTION :

A planetary gear systems, also known as epicyclic gear systems, is made up of three types of gears; a sun gear, planet gears, and a ring gear. The sun gear is located at the center, and transmits torque to the planet gears which are typically mounted on a moveable carrier. The planet gears orbit around the sun gear and mesh with an outer ring gear. Planetary gear systems can vary in complexity from very simple to intricate compound systems, depending on the application.

Planetary gears are often used when space and weight are an issue, but a large amount of speed reduction and torque are needed. This requirement applies to a variety of industries, including tractors and construction equipment where a large amount of torque is needed to drive the wheels. Other places you will find planetary gear sets include turbine engines, automatic transmissions, and even electric screwdrivers.

Planetary gear systems are able to produce a lot of torque because the load is shared among multiple planet gears. This arrangement also creates more contact surfaces and a larger contact area between the gears than a traditional parallel axis gear system. Because of this, in the load is more evenly distributed and therefore the gears are more resistant to damage.

OBJECTIVE :

The objective of this challenge is to simulate the motion analysis on the planetary gear assembly consisting of a sun gear, a ring gear, a carrier and four planet gears and to do required post-processing of the results.

INPUT PARAMETRS :

Simulation is run for 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

DIMENSIONAL SPECIFICATIONS OF GEARS :

1. INPUT SPEED OF SUN GEAR = 200 RPM

2. NUMBER OF PLANETERY GEARS = 4

3. GEOMETRIC SPECIFICATION TABLE

S. No.	Component	Module	Number of Teeths
1.	Sun Gear	2.5	14
2.	Ring Gear	2.5	46
3.	Planetery Gear	2.5	t (say) = 16

In order to calculate the number of teeth for planetry gear say t, we need to find its pitch diameter (Pd)

From theory, we known

MODULE (m) = Pitch Diameter (Pd)/ Number of teeth (t) ---------------------------- (1)

Since, Pitch diameter of Planetery Gear = (Pitch diameter of Ring Gear - Pitch diameter of Sun Gear) /2

= (115 mm - 35 mm) /2

= 40 mm

Therefore, from eq (1)

Number of teeth (t) for each Planetery Gear = 40 / 2.5

= 16.

REQUIRED CAD MODELS

1. Uploaded model of Ring Gear

2. Uploaded model of Sun Gear

3. Uploaded model of Planetery Gear

4. Uploaded model of Carrier

5. Assembly Model of Gears

6. Full Assembly

PROCEDURE

FIRST, design the assembly. This means importing the required gears with particular specifications from the Tool package.

SECOND, align them in their required positions i.e, on the same plane.

THIRD, measure the required dimensions in order to deisgn the carrier.

FOURTH, Mate the gears in the assembly workbench to make figure constrained. Check that the planetary gears and sun gears can rotate on its own axis freely to ensure proper constraint.

FIFTH,Open the Motion solid works add on and select motio analysis. Fix the required component and give the required torque to the gears for each cases.

SIXTH, Run the simulation and capture the results for each cases.

RESULTS: PLOTS

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

CONCLUSIONS

1. When the torque is applies to Sun Gear and output is Carrier keeping Ring Gear fix, the angular velocity is in between 200 deg/sec and 330 deg/sec. The variation is of 130 deg/sec.

2. When the torque is applies to Ring Gear and output is Carrier keeping Sun Gear fix, there is a sudden increase in angular velocity. The angular velocity is in between 1005 deg/sec and 812 deg/sec. The variation is of 193 deg/sec.

3. When the torque is applies to Sun Gear and output is Ring Gear keeping Carrier fix, the angular velocity is in between 320 deg/sec and 423 deg/sec. The variation is of only 103 deg/sec.

From above results, Case 2 has recorded highest Angular velocity and maximum variation in Angular velocity.

Note : I hereby attached the images of CAD model since I don't find proper way to insert CAD model in this word file with limited options.