Final Topic Proposal
Introduction:
As a group, we decided to do our team based reverse engineering project on an oscillating house fan. We will begin with a history of the fan and then branch out into different categories regarding the applicable aspects of engineering with respect to our oscillating fan. We have included a description of the mechanical, electrical, and industrial engineering aspects of the fan, and we have also analyzed the marketability, ethics, cost effectiveness, and improvability of the current fan design. We would like our project to demonstrate how many areas of engineering apply in our daily lives and how engineering is constantly helping people in their daily lives
Chapter 1 - History of the Fan:
The fan is one of the earliest known mechanical inventions. Throughout time, fans have been regarded as a symbol of status or fashion and as an implement used to keep oneself cool. The first known fans were usually constructed out of large leaves or feathers and were usually operated by servants to keep their masters cool in the hot summer. In the Middle East, many examples of these early fans have been discovered in Egyptian and Assyrian tombs. Some of the most famous of these fans were found in King Tutankhamen's tomb. They were made out of pure gold and ostrich feathers. Many other cultures also employed the use of such fans. In the Americas, the Aztecs, Mayas, and other South American cultures used fans for a variety of religious ceremonies. In the Mediterranean, the Greek culture used fans that had a piece of linen stretched over a leaf shaped frame. The Roman culture also used fans, which consisted of large pieces of painted wood. In China, many early groups of people believed that fans were in some way related to mythical and historical folklore. Later on, the Chinese developed the folding fan during the Ming dynasty between the years of 1368 and 1644. At this time, these fans became very popular among the Chinese people and were even used as weapons known as tieshans or iron fans. Around this time, fans made their way over to Europe with the help of the Crusaders. The mass importation of fans didn't come until the 15th century when Portuguese traders began to bring fans back to Europe from the Orient. These fans became very popular and many high class women of the time were seen holding fans in various portraits. The first mechanical fans, the punkahs, were developed in the Middle East in the 1500's. These fans were huge wooden frames mounted to the ceiling that were covered in canvas. They were operated by servants known as punkah wallahs, who pulled on pieces of rope that made the fan move back and forth. The next innovation in fan technology didn't come for nearly 300 years. A man named Dr. Schuyler Skaats Wheeler combined the research and technology of Thomas Edison and Nikola Tesla to make the first electric house fan. This fan consisted of a motor and two blades that rotated and created a small amount of air flow. 1882, Philip H. Diehl improved on Wheeler's design and developed a way to mount one of his fans on the ceiling of a room, thus the ceiling fan was born. He then went on to found Diehl & Amp, Company and began to sell these fans. He branched out into making table fans, industrial fans, and all sorts of other variations. He continued to make improvement on his fans and eventually developed a gearing system that allowed table fans to oscillate back and forth so that they could do a better job at circulating air. Since then, these fans have been an easy and cheap way to cool off rooms and to move air around, and to this day, are still one of the most common forms of air circulation.
Note: Figures are avaliable through the posted link.
Chapter 2 - Mechanical Engineering Aspect:
Mechanical engineers deal with many aspects of a household fan such as air moved, aerodynamics of fan blades, oscillation, balance of the fan, and the stand to support the fan. First, mechanical engineers work on the amount of air flow from fan. The goal is to have the greatest amount of airflow with the minimum amount of power used and the least amount of unwanted noise. This goal is attained by reducing friction between moving parts of the fan, and by working with electrical engineers to make sure enough power is given to the motor to create enough force to rotate the fan blade. It is also attained by limiting the vibrations when the fan is operational to prolong the life of the fan and cut down on unwanted noise. Mechanical engineers also work on the aerodynamics of the fan blades used. The desire is to have the blades push the most amount of air through the fan, but also keep the dust collection to a minimum. As shown in Figure 1, our fan utilized an array of streamlined blades that efficiently moved air through the fan.
Mechanical engineers must also construct the oscillation of the fan, which is a feature that most consumers look for. After taking apart the fan, we discovered that the oscillation works by a series of gears and a swing arm, which is attached to the main motor. (Figure 2) The oscillator was driven by the motor, which used a simple worm gear to increase the mechanical advantage. (Figure 3) The oscillating function can also be turned off. There is a button on the fan housing that pulls a gear in and out of contact with the worm gear, which controls the oscillation.
After discovering this, engineers must also design the stand of the fan, so it can support the weight of the fan, and also so it will not tip over while the fan is oscillating. Our fan had a square shaped base that had enough surface area to properly support the fan (Figure 4)
Chapter 3 - Electrical Engineering Aspect:
The electrical aspect of the fan is a very important part of making the fan work properly and efficiently. The electrical system of this fan is very simple. It consists of a cord that plugs into a power outlet, a control panel, which has 4 buttons to control the fan speed, and an electric motor that drives the entire fan assembly. The power cord is used to transfer AC power from a wall outlet to the fan for distribution and use by the electrical system. This power is controlled through the control panel which consists of four buttons. One button turns the fan off and the other three control how fast the fan spins. (Figure 5) This unit controls the speed of the fan by moderating the amount of voltage that actually gets to the motor. The motor is the primary electrical component of the fan. (Figure 6) It consists of a field magnet, an armature, a commutator, and brushes. (Figure 7) The brushes rub on the commutator, which provides electricity for the armature. The armature is then turned, due to the fact that there is a repulsion force when an electric current is run through a magnetic field which is provided by the field magnet.
Chapter 4 - Industrial Engineering Aspect:
When designing a fan, the manufacturing cost, safety, and efficiency must be taken into account. It is clear that the designers of this fan addressed the manufacturing costs by using plastics instead of metals wherever possible. (Figure 8) For example, they seemed to have used an injection molding technique to make the frame/stand which would greatly increase efficiency and reduce manufacturing costs with respect to machining every part that they needed. They also used plastic gears wherever possible due to the fact that plastic gears are much less expensive than metal gears. (Figure 2) The motor was the only feature of this fan that seemed to neglect cost effectiveness and emphasized quality since it was made out of non-inferior materials. (Figure 7) The aspects of safety were shown by the way the engineers used a cage to surround the fan blades to keep people from coming into contact with them. The cage was made out of metal and also seemed to emphasize safety over cost effectiveness.
Chapter 5 - Cost effectiveness, Marketability, Ethics:
Other than the three big engineering aspects of this product, there are many other things that one must examine to gain a full understanding of this item, such as the cost effectiveness of the design, the prospective marketability, the ethics of this product and any possible design improvements.
The design of this product is fairly cost effective. As stated before, it uses plastic parts wherever possible, and most of the pieces are modular to make the assembly process much easier. (Figure 8)
This product definitely has a wide range of marketability. Wherever there is heat, there is a need for a fan. Therefore, this device can be sold to just about anyone who is searching for a nice cool breeze on a hot summer day.
The designers of this fan also took into account engineering ethics. They managed to be cost effective on parts that are not easily broken, but when it comes to the parts that endure a heavy duty cycle, they have focused on quality. For example, the motor is the most heavily used part of this fan, and the manufacturers have decided to use a motor that can withstand years of use. The designers also took into account the safety of the individual. They have surrounded the blades with a metal cage that keeps people from being injured from the moving parts. (Figure 9) It is clear that the engineers have taken many of these aspects into consideration when they designed this product.
Chapter 6 - Design Improvements:
The final part of our project is whether or not any design improvements can be made to this fan. One design improvement could be to have a setting that allows the user to decide how far they want the fan to oscillate. Another improvement could be to enable the fan to not only oscillate from side to side, but up and down as well. Unfortunately, these design improvements would be very costly and would not be very beneficial from an economic standpoint. The only improvement that would be cost effective and easy to incorporate into the design would be to add a time to turn the fan off even when you are not in the room.
Chapter 7 - Conclusion:
In conclusion, there are many aspects of the normal house fan which reflect the various branches of engineering. It demonstrates the use of Mechanical Engineering by being a device with multiple moving parts and gear systems. The Electrical Engineering aspect is shown by the use of a motor and a simple control panel to regulate the speed of the motor. Finally, the Industrial Engineering aspect is manifested in the materials that the designers used, and the way in which they used them to efficiently and cost effectively produce this fan.
References:
http://www.howstuffworks.com/
http://en.wikipedia.org/wiki/Fan_(implement)
http://www.ceilingfan.com/