Planetary Gear
AIM
Design of Planetary gear system with four planet gears and analyzing the angular velocities for different cases.
INTRODUCTION
Epicyclic gear train is used to set different gear ratios by with the help of different sets of gear sun gear, planet gear, and ring gear. Planet gears with their size engage a lot of teeth as they revolve around the sun gear. Hence, they can easily accommodate numerous turns of the driver for each output shaft revolution. There is an increase in load capacity and torsional rigidity if we increase the number of planet gears. Moreover, all the planet gears are mounted to a single rotating member, called a cage, arm, or carrier where the output is obtained. The most important thing is module should be same for all the gear system.
Different gear system
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
Module =
For Ring gear PCD = 46*2.5 = 115
For Sun Gear PCD = 14*2.5 = 35
by geometry we got the PCD of planetary gear=40
Number of teeth in Planetary Gear = 40/2.5 = 16
| Sl.No | Input | Output | Fixed |
| 1 | Sun Gear | Carrier | Ring Gear |
| 2 | Ring Gear | Carrier | Sun Gear |
| 3 | Sun Gear | Ring Gear | Carrier |
Models created
1.SUN GEAR
2.PLANETARY GEAR
3.RING GEAR
4.CARRIER
5.ASSEMBLY
LINK FOR PART AND ASSEMBLY
https://drive.google.com/drive/folders/1Q2dowRT8tEbKuEvgsrwwv2wd6I5Dc_cq?usp=sharing
Case 1: Fixing the Ring Gear, input to the sun gear and output from carrier
Input
OUTPUT
CASE 2
Fix the Sun gear, input to Ring gear and obtain output at the carrier
INPUT
OUTPUT
CASE 3
Fix the carrier, input to the sun gear, obtaining output at the ring gear
INPUT
OUTPUT
RESULTS
As we can observe from the above plots we obtain different outputs of angular velocity for the same input angular velocity by changing the driving wheel.
CASE 1
When the ring gear is fixed and input is given to the sun gear, at the point of contact between the sun and the planet gear, the velocity will become same, but at a point where the planetary gear is in contact with the ring gear the velocity will be zero .So, in order to satisfy the condition, the planet gear should rotate as well as revolve simultaneously to satisfy both these conditions. In velocity formula (V=Rw) v=rw"> the mating point of sun and planet gear and input is given to the sun gear. Hence, speed depends on the radius of the sun gear for this case.
Case 2
The input is will be given to ring gear and the sun gear will be fixed, the ring gear will rotate the planet gear and the point of contact between the planet and ring gear should have the same velocity and also the velocity of mating point of sun and planet gear should be zero,so in order to satisfy this condition, the planet gear will rotate as well as revolve, but the output obtained will be more as R in (v=rw">v=Rw)is greater for ring gear and hence output obtained will be more than the case 1,which can be visualized from the plots.
Case 3
The carrier will be fixed, so that planet gears will only spin and will not revolve around the sun gear, and the output will be obtained at the ring gear which will spin in an opposite direction to the sun gear and hence a reverse gear will be obtained.
Conclusions:
- From the above assembly we obtain different speeds that we require which can be used in transmission.
- Disturbances will occur at the output due to mating of gears
- Output angular velocity will be less than the input angular velocity due to gear ratios