Planetary Gear
Aim: To create 3D model for Planetary Gear system and simulation of the mechanism for motion study of different links while changing the input links.
Introduction:
Planetary gear system is a type of Compound gear train where we can find a vast range of speed variations. They are used in Automatic Transmission and transmission in Helicopters etc.
It mainly consists of a sun gear, a number of planetary gears surrounding the sun gear, an internal Ring gear which connects the planets gear and a carrier which connects the planet gears.
There can be cases where we can fix one component and study the relation of the other two links.
we will discuss the mechanisms and study setup while understanding cases.
Let us start
Given Data:
Ring gear
Module (m) = 2.5
Number of teeth (T) = 46
The expression for Pitch circle Diameter is
Therefore, `D =2.5×46=115 mm`
Sun Gear
Number of teeth (T) = 14
Module (m) = 2.5 (same for all gears)
Therefore,
`D =2.5×14=35 mm`
Now for 4 planetary gears
We know pitch circles of the mating gears must be tangent to each other therefore we can calculate the Pitch circle diameter by geometry of mating gears.
Therefore,
`D =40 mm`
Now we can calculate No of teeth on the Planetary gear by,
`T =D/m=40/2.5=16`
Input speed to various links: 200 RPM
Now,let us assign inputs to different links and plot the graphs to understand the outputs.
Case 1:
| Input | Output | Fixed |
| Sun Gear | Carrier | Ring Gear |
Study setup
First of all Solid works Motion must be enabled in Solid works Add-ins ribbon
Now, with motion study enabled.
we give the input to sun gear
Here, we will give input speed to sun gear which will rotate the planet gears in opposite direction but the ring gear is fixed which planet gear will try to rotate it in the same direction of the sun gear. So fixed ring gear will transfer a toque to the planet gears which will rotate the carrier connected to it. Rotation effect is transferred to the carrier as the planet gear rotates as well as translate
Plot:
In the Plot above we can understand as the motion starts to transmit it takes little time as the contacts begin to happen among different gear teeths. Angular velocity continues to variate in the process as there are axial thrust which happens while engaging and disengaging of gear tooth in Spure Gear.
The average angular velocity after exporting data to spreadsheet is 279.48 degree/sec
Animation Link:
https://drive.google.com/file/d/1DoxPra7dMfZEAIgJjo0zqLevLrmKT9rp/view?usp=sharing
Case 2:
| Input | Output | Fixed |
| Ring Gear | Carrier | Sun Gear |
Study setup
Here, we will give input speed to ring gear which will rotate the planet gears in opposite direction but the sun gear is fixed which planet gear will try to rotate it in the same direction of the ring gear. So fixed sun gear will transfer a toque to the planet gears which will rotate the carrier connected to it. Rotation effect is transferred to the carrier as the planet gear rotates as well as translate. This case is exactly opposite to the case 1
Plot:
In the Plot above we can understand as the motion starts to transmit it takes little time as the contacts begin to happen among different gear teeths. Angular velocity continues to variate in the process as there are axial thrust which happens while engaging and disengaging of gear tooth in Spure Gear.
here the average velocity of the carrier increases as the point of added effect of rotation and translation is at the ring gear pitch circle diameter. The average angular velocity after exporting data to spreadsheet is 916.54 degree/sec
Animation Link:
https://drive.google.com/file/d/1ausOGc1PwHNIR0RxRgYFq89bz3Q4te4X/view?usp=sharing
Case 3:
| Input | Output | Fixed |
| Sun Gear | Ring Gear | Carrier |
Study setup
In this case sun gear is rotated and as the carrier is fixed, the planet gears rotates about their own axis and transmits the torque to the ring gear. As a result ring gear rotates in the same direction as of the planet gear.
Plot:
Here the average velocity of the carrier increases as the point of added effect of rotation and translation is at the ring gear pitch circle diameter. The average angular velocity after exporting data to spreadsheet is 364.55 degree/sec
Animation Link:
https://drive.google.com/file/d/1DZ9_lT2F0EVNsEnlzvqMyZd0kp0Y1G71/view?usp=sharing