To Model and Simulate a Planetary Gear System in SolidWorks
Aim: To model and simulate a Planetary Gear System in Solidworks and perform Motion Study Analysis
Introduction:
At first glance, planetary gear systems, also known as epicyclic gear systems, appear to be quite complex. It is certainly true that it takes a skilled gear engineer to master all of the intricate aspects of designing this type of gear system. If you are an advanced gear engineer, this post isn’t for you. But if you are looking for a more basic understanding of planetary gears, you’ve come to the right place.
What are Planetary Gears?
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 centre (yellow), and transmits torque to the planet gears (blue) which are typically mounted on a moveable carrier (green). The planet gears orbit around the sun gear and mesh with outer ring gear (pink). Planetary gear systems can vary in complexity from very simple to intricate compound systems, depending on the application.
Where are Planetary Gear Systems Used?
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.
Manufacturing Planetary Gears
The skills required to manufacture planetary gears are the same as those required for any other type of precision gear manufacturing. Gear Motions is a leading precision gear manufacturer specializing in supplying custom cut and ground gears. We have an extensive portfolio of gear production capabilities which includes the ability to produce all of the individual gears that make up a planetary gear system. For specific manufacturing capabilities such as minimum and maximum diameter, pitch diameter, and face width, please visit our gear production capabilities page. Please note we do not manufacture gearboxes.
Gear Motions also has extensive experience when it comes to gear engineering and design. Whether you need to design a gear system from scratch, or need assistance with a redesign, we will work with you through the entire process to ensure your gears are designed and manufactured with precision. Engineering services include reverse engineering, design for manufacturability, prototyping, and redesign.
SolidWorks Part Design Procedure
Since we are using the toolbox components, we do not need to design the gears separately. With the help of the module and number of gear teeth, the pitch circle diameter and gear ratio for gear meshing.
Given:
Module = 2.5
Ring Gear (Internal Spur Gear)
Number of teeth = 46
PCD = 115mm
Sun Gear (Spur Gear)
Number of teeth = 14
PCD = 35mm
Shaft = 18mm
Planet Gears (Spur Gear)
Number of planet gears = 4
PCD = 40mm
Shaft = 10mm
Carrier
Diameter = 115mm
Shaft = 10mm
Open SolidWorks, select a new file and select Assembly. Once you are in part; go to sketch and select the right plane.
Draw three circles of radius 115mm,40mm and 35mm (from the centre of the plane)
Now, define the sketch by making a 40mm circle tangent with the 35mm circle and make it horizontal as well. Now, go to circular sketch pattern and selecting the 40mm circle, make it pattern along with the centre of the plane and after this exit the sketch.
Now, Go to Design Library and select ANSI Metric Toolbox, then go to power transmissions, then gear and then select the internal spur gear for the ring gear and select spur gear with dimensions mentioned above for sun gear as well as all the four planetary gears. And assemble them according to the sketch.
Sketch the carrier in a new part window and add it into the assembly and constrain it so that it has one degree of freedom (DOF).
Assembly:
These are the mates provided for the assembly.
Motion Study:
Go to SolidWorks Add-Ins and select SolidWorks Motion.
Select Motion Analysis for the motion study. Input speed of gear = 200 rpm.
Task 1:
Input - Sun Gear
Fixed - Ring Gear
Output - Carrier
I added all the contacts between the solid bodies and added a rotary motor on the Sun gear axis at a speed of 200 rpm with a frame rate of 1200.
The plot is plotted with Angular Velocity against Time as shown below. I used the carrier outer face for the output.
Task 2:
Input - Ring Gear
Fixed - Sun Gear
Output - Carrier
I added all the contacts between the solid bodies and added a rotary motor on the ring gear axis at a speed of 200 rpm with a frame rate of 1200.
The plot is plotted with Angular Velocity against Time as shown below. I used the carrier outer face for the output.
Task 3:
Input - Sun Gear
Fixed - Carrier
Output - Ring Gear
I added all the contacts between the solid bodies and added a rotary motor on the ring gear axis at a speed of 200 rpm with a frame rate of 1200.
The plot is plotted with Angular Velocity against Time as shown below. I used the sun gear shaft face for the output.
Results and Explanation:
What can be deducted from the above studies is that the motion when it is transferred from gear to gear, will have certainly some fluctuation/disturbance (losses) but when it meshes correctly and the input is given to the correct part, then a steady output will be obtained.