DESIGN AND MBD OF PLANETARY GEAR SYSTEM (using SOLIDWORKS)
AIM:
To design and do the motion analysis of various configurations of the Planetary System using SOLIDWORKS
OBJECTIVES:
- To understand the various models and the mechanics behind the models of the planetary gear system
- To design the models via SOLIDWORKS and do the analysis of their motion.
INTRODUCTION:
A planetary gear set 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.
The carrier can be seen as follows:
GIVEN PARAMETERS :
Module of each of the gears = `2.5`
No. of teeth in the ring gear = `46`
No. of teeth in the sun gear = `14`
PCD of any gear = Module `X` No. of teeth
So, PCD of ring gear = `(2.5)*46 = 115 mm`
PCD of sun gear = `(2.5)*14 = 35 mm`
So, as per the figure,
PCD of the planet gear = `(PCD` of ring`-PCD` of sun) `/2` = `40 mm`
No. of teeth of the planet gear = `40/2.5 = 16`
Input `RPM` = 200
PROCEDURE OF THE DESIGN:
- First, in the assembly part, all the gears are imported from the Design library from ANSI metric system.
- Then, as per the sketch and the calculations, all of them are aligned.
- Then, a carrier was made whose diameters of the connecting rod are equal to that of nominal shaft diameter of the planet gears.
- Then, all of them were assembled and were ready for motion analysis.
ASSEMBLY OF THE MODEL:
The parts and the assembly of the models can be seen through the following link:
https://drive.google.com/drive/folders/1Ptl82zNwmdegDAmqgtCWoYzuFlSVG62j?usp=sharing
OBSERVATIONS :
- When the ring is fixed and input is given to the sun gear and output is taken from the ring gear,
Angular velocity of the sun gear:
Angular velocity of the ring gear:
- When the ring gear is fixed, input is given through sun gear and output is taken from the carrier,
Angular velocity of the sun gear:
Angular velocity of the carrier:
- When the sun gear is fixed, the input is given through ring gear and the output is taken from the carrier,
Angular velocity of the ring gear:
Angular velocity of the carrier:
SIMULATION OF THE VARIOUS MODELS OF PLANETARY GEAR MECHANISM:
Motion of the planetary gear system when career is fixed can be seen thorugh the following link:
Motion of the planetary gear system when the ring gear is fixed can be seen through the following link:
Motion of the planetary gear system when the sun gear is fixed can be seen through the following link:
CONCLUSION:
We can conclude out of the three cases that the angular velocity in the output is highest in the last part. So, to get maximum amount of torque, we can use the last case.
The angular velocity drops highly in the second case comparing to the other two cases. Also, the drop in angular velcoity is less in the first case than that of the other cases. So, in order to get a stable kind of torque, we can use the first condition.