MOTION ANALYSIS OF PLANETARY GEAR
1.AIM :
TO ANALYSE THE PLANETARY GEAR USING SOLIDWORKS MOTION ANALYSIS
2.OBJECTIVE :
- To design 3D model of planetary gear using given inputs.
- To perform motion analysis at 200 rpm rotation speed of input gear for 3 conditions.
- To export the results to excel sheet and plot angular velocity as function of time of output component.
3.INTRODUCTION :
A planetary gear or epicyclic gear train is a gear mechanism consisting of 4 components, namely, sun gear,planet gears (arranged around sun gear), internal gear and carrier that connects planet gears.
Since this arrangement is reminiscent of planets orbiting the sun, the central wheel is referred to as the sun gear, while the surrounding ones are called planet gears, they are located within an external gear ring which gives this the name planetary gear. The sun gear is driven by a motor and transmits its motion to the surrounding planet gears, which roll against the surrounding gear ring and thus orbit the sun gear evenly. The planet gears are mounted on a carrier that is connected to the output shaft.
Here the subject of study is motion analysis of planetary gear using SOLIDWORKS for 3 conditons and plot angular velocity as function of time of output component.
4.MODEL AND ASSEMBLY :
As per the given inputs for designing the Planetary Gear following calculations were performed:-
Ring Gear
Module = 2.5
Number of teeth = 46
Sun Gear
Number of teeth = 14
Input Speed of the Gear = 200 rpm.
Number of planet gears = 4
Calculations
The module (m) of a gear is ratio of pitch circle diameter (d) to no of teeth (T)
`m= d/T`
for Ring gear
Module,m = 2.5
Number of teeth, T = 46
So, pitch circle diameter, `d=m*T`
`d = (2.5)*(46)`
`d = 115`
for Sun gear
Module,m = 2.5
Number of teeth, T = 14
So, pitch circle diameter, `d=m*T`
`d = (2.5)*(14)`
`d = 35`
for planet gear
Module,m = 2.5
Radius of Ring Gear = Radius of Sun gear + Diameter of planet gear
`((m*T)/2)_"ring" = ((m*T)/2)_"sun" + (m*T)_"planet"`
`T_"ring" = T_"sun" + (2*T)_"planet"`
`46 = 14+ (2*T)_"planet"`
Number of teeth, `T_"planet" = 16`
So, pitch circle diameter, `d = (2.5)*(16)`
`d = 40`
As per the calculated values the gears ANSI Metric gears were selected from the design modeller available in the Solidworks and a carrier was designed as per the nominal shaft diameter of 15mm of planet gear.
Ring gear
Sun gear
Planet gear
Carrier
Assembly
The assembly is done using mating the parts properly and aligning all the components so that there is no component overlap on each other. Here we are not using mechanical gear mates as we have to analyze the motion for 3 cases.
5.MOTION ANALYSIS :
Motion analysis for the planetary gear can be done using the SOLIDWORKS Motion feature available as an add-on in the solidworks, innside this feature the option motion analysis can be used to perform the operation.
To rotate the input gear component a constant 200 RPM motor is assigned to that component, further a solid body contact is established between the components using the contact option, also the material steel is chosen for all the parts.
The moiton analysis study is conducted for 3 conditions as shown below
| SL. NO | INPUT | OUTPUT | FIXED |
| 1 | SUN GEAR | CARRIER | RING GEAR |
| 2 | RING GEAR | CARRIER | SUN GEAR |
| 3 | SUN GEAR | RING GEAR | CARRIER |
- INPUT- Rotary Motion is given to that part as input.
- OUTPUT- After motion analysis, Angular Velocity of that part is plotted as a graph.
- FIXED-Make that particular component as a fixed part.
6.RESULTS :
The plots for Angular velocity as a function of time of the output component for 3 conditions are given below:-
CONDITION 1 (INPUT TO SUN GEAR, RING GEAR FIXED AND OUTPUT AT CARRIER)-
In this case when the input is given to the sun gear 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 along with the carrier as the Ring gear is fixed. The angular velocity of carrier varies between 260-290 deg/sec.
Animation video:-
CONDITION 2 (INPUT TO RING GEAR, SUN GEAR FIXED AND OUTPUT AT CARRIER)-
In this case when the input is given to the ring gear keeping the sun gear fixed, the planet gear and ring gear rotate about their axis and planet gear also roll on inside of ring gear. The angular velocity of carrier varies between 850-950 deg/sec.
Animation video:-
CONDITION 3 (INPUT TO SUN GEAR, CARRIER FIXED AND OUTPUT AT RING GEAR)-
In this case, the carrier is fixed and the input is given to sun gear, all the gears rotate about their axis but carrier being fixed does not allow planet gear to roll on the ring gear. The angular velocity of ring gear varies between 350-400 deg/sec.
Animation video:-
Link to the solidworks and excel files:-
https://drive.google.com/drive/folders/1jcYoaZOwPS8gZao4QMSOhRRLgrk-XN3b?usp=sharing
7.CONCLUSION :
The motion analysis of the planetary gear for all 3 conditions was completed.
Motion analysis helps to simulate the real time perfomance and give various results and plots to better understand the working.