Planetary Gear
Planetary Gear
Aim: - Motion analysis on the planetary gear Assembly
Input data are given in below,
Ring Gear
Module = 2.5 (You must use the metric system in design modeller)
Number of teeth = 46
Sun Gear
Number of teeth = 14
Input Speed of the Gear = 200 rpm.
Number of planet gears = 4
With the above input parameters, you are going to run a simulation on the following cases,
Find out: - After motion analysis, Angular Velocity of that part is plotted as a graph.
PLANETARY GEAR: -
Planetary gear also known as epicyclical gear train. It consists of a larger Ring gear, planet gears and a sun gear. The sun gear is mounted at the centre around which the Planet gears are mounted which can revolve around them. The planet gears are meshing internally with the Ring gear which is an internal gear. A carrier is mounted to the planet gears as shown in the image. The combination of epicycle gear trains with a planet engaging both a sun gear and a ring gear is called a planetary gear train.
Calculation Planetary Gears:
The module is the same for all the gears.
The relation between the pitch circle diameter and no. of teeth is as follows -
D = m * t
D = pitch diameter
m = module and t = no. of teeth
Diameter of ring gear / 2= Diameter of planetary gear + Diameter of sun gear / 2
115/2 = Diameter of planetary gear + 35 / 2
D.P. (Diameter of planetary gear) = 57.5 -17.5 = 40mm
|
Type of gear |
Pitch Diameter |
Module |
No. of teeth |
|
Sun Gear |
35 mm |
2.5 |
14 |
|
Ring Gear |
115 mm |
2.5 |
46 |
|
Planetary Gear |
40 mm |
2.5 |
16 |
Creating a Geometry and Assembly: -
CREATING GEAR FROM TOOLBOX -
GO TO DESIGN LIBRARY - TOOLBOX - ANSI METRIC - POWER TRANSMISSION - GEARS
Sun and planetary gears = Spur gear
Ring gear = Internal Spur Gear
Pressure angle = 20 degree
Face Width = 20 mm
Procedure
- Select the Motion solid works add on and select motion analysis.
- Fix the component and provide the required torque to the gears.
- Make sure that the contact solids include all the components including the carrier and all the gears.
- Run the simulation.
- Save the video.
Motion analysis -
- before going into cases add contact pairs -
- There are total 8 contact pairs -
- 4 contact pairs - associating with a sun gear and planetary gear
- 4 contact pairs - associating with a Ring gear and planetary gear
. MODELS AND ASSEMBLY:
Internal Gear/Ring Gear
Sun Gear
Planetary Gears
Carrier
Assembly
RESULTS:
Case 1:
Ring gear fixed
Motor - sun gear - 200 rpm
The plot of an angular velocity of the carrier against time
Case 2
Sun gear fixed
Motor - Ring gear - 200 rpm
The plot of an angular velocity of the carrier against time
Case 3
Carrier fixed
Motor - Sun gear - 200 rpm
The plot of an angular velocity of the Ring against time
CONCLUSION: -
When the input is given 200 rpm to the sun gear and output is obtained at the carrier keeping the ring gear fixed. The planet gear not only rotates about their axis but are also forced to roll on the inside of the ring gear since it is fixed. When the input is given to the ring gear 200 rpm and output is obtained from the carrier keeping the sun gear fixed. The angular velocity achieved is maximum since the internal gear is big and planet gears are small comparatively so when a large gear meshes with a small gear the velocity achieved from the small gear is high because the velocity ratio is high. A this can be seen in the plot of angular velocity. When a carrier is fixed and output is to be obtained from the ring gear the opposite happens. The planet gears rotate only about their axis and transmit motion from sun to the ring and since the ring gear is big in diameter the angular velocity achieved is less.
SIMULATION VIDEO LINK