PLANETARY GEAR
AIM
To perform MBD on Planetary Gear using Soildworks.
OBJECTIVES
To run the simulation for the following cases with input motor speed of 200 rpm and plot the graph for angular velocity at the output.
|
S. No |
Input |
Output |
Fixed |
|
1 |
Sun Gear |
Carrier |
Ring Gear |
|
2 |
Ring Gear |
Carrier |
Sun Gear |
|
3 |
Sun Gear |
Ring Gear |
Carrier |
THEORY
Epicyclic gear train also known as Planetary gears consists of multiple gears so that the centre of one gear revolves around the centre of another gear. The following are the types of gears present in epicyclic gear system. The sun gear and planet gear mesh so that the pitch circle revolves without slip.
- Sun Gear
- Planet Gear
- Ring Gear
- Carrier
Automatic transmission system employs the use of planetary gear system to transfer power and multiple engine torque.
GEAR MODULE
Module is the unit size that indicates how big or small a gear is. It is the ratio of reference diameter of the gear to the total number of teeth. The module is same for all the gears in planetary gear system.
CALCULATION OF PCD AND NUMBER OF GEAR TEETH
The following are the conditions given for the planetary gear system.
Module = 2.5
No of teeth for ring gear = 46
No of teeth for sun gear = 14
The number of teeth for planet gear can be calculated using the following formula
`R=2P+S`
where
R is the number of teeth in ring gear.
P is the number of teeth in planet gear.
S is the number of teeth in sun gear.
`46=2P+14`
`46-14=2P`
`32=2P`
`P=16`
The PCD can be calculated using the following formula
`m= D/T`
`D=mT`
where
T is the number of teeth.
D is the diameter of the gear.
m is the gear module.
|
GEARS |
m | T |
`D=mT` |
|
Ring |
2.5 |
46 |
115 |
|
Sun |
2.5 |
14 |
35 |
|
Planet |
2.5 |
16 |
40 |
The following represents the 3D model for different gears.
SUN GEAR
PLANET GEARS
RING GEAR
CARRIER
ASSEMBLED MODEL
PROCEDURE
- Gears can be imported using the Soildworks library.
- Click on Soildworks library and select Toolbox.
- From the toolbox select Power Transmission and then click on Gears.
- Select Internal Spur gear for Ring gear and Spur gear for Sun and Planet Gears.
- Specify the no of teeth, module, pressure angle as 20 and face width as 20.
- The no of teeth varies for different gears. All the other parameters remain the same.
- The carrier is constructed based on the pitch circle diameters of the gears. Four pins are also created in order to hold the planet gears.
- Open Soildworks Assembly and import the carrier.
- Specify the constraints for the carrier so that the carrier rotates about its axis.
- Import the gears using Solidworks library.
- Mate the gears and carrier using the required constraints.
- Check the interference between gear teeth. There should not be any interference.
- Select Motion Study from Solidworks Add-Ins.
- 200 rpm is given as motor speed.
- The contact is established between the gears. Steel dry is the material selected.
- The motion study is done according to the given conditions.
- Click on Calculate to run the study.
The following are the results obtained under different conditions.
PARAMETRS
Input - Rotary motion of 200 rpm is given as input.
Output – Angular velocity is plotted as a graph.
Fixed – The particular component is fixed
CASE 1
Input – Ring gear
Output – Carrier
Fixed – Sun Gear
ANGULAR VELOCITY PLOT
The maximum angular velocity is `1206 deg⁄s.`
ANIMATION LINK
CASE 2
Input – Sun Gear
Output – Ring Gear
Fixed – Carrier
ANGULAR VELOCITY PLOT
The maximum angular velocity is `384 deg⁄s`
ANIMATION LINK
CASE 3
Input – Sun Gear
Output – Carrier
Fixed – Ring Gear
ANIMATION LINK
PART DRAWING
https://drive.google.com/file/d/1_WKxr-IqdOQOOX2ydhshbovSMpsg92wx/view?usp=sharing
RESULTS
The motion study for the given conditions are carried out successfully.
The angular velocity is maximum when the sun gear is fixed.
REFERENCES
Wikipedia