Ratcheting screwdriver
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Revision as of 21:31, 23 September 2007
Contents |
Executive Summary
Customer Needs
Easy to Use
-ratcheting/electric
-portable
-interchangeable bits
Practicality
-screwing/unscrewing
-affordable
-comfortable
-durable
System Functionality
Ratcheting Screwdriver
On the interior of the head piece of the screwdriver, there is an internal ring gear that connects with 2 pawls on the base piece of the screwdriver. The pawls are located at the front of the base piece, each consisting of a flat side and a curved side. When both are engaged, the ratcheting motion is locked, and the device acts as a regular screwdriver. A switch depresses either of the 2 pawls, pushing one into a recessed area and leaving the other engaged. With one pawl depressed, the gear is free to ratchet in one direction. A switch on the handle of the screwdriver allows the user to easily switch from depressing either of the pawls, or leave both engaged
Portable Electric Screwdriver
DFE
Ratcheting Screwdriver:
The power generation and supply for building 1 million dollars worth of ratcheting screwdrivers is 197 millions tons of CO2 and 2.4 million tons of CFCs, which are both considered greenhouse gases (resource 1). The power used to create the ratcheting screwdriver is mainly provided by coal power plants (1.8 terajoules (TJs)) and natural gas power plants (.420 TJ) (resource 2). The use of nuclear power plants would drastically decrease the greenhouse gases produced from power production. Nuclear power plants produce little to no greenhouse gases. Although, the drawback of nuclear power plants is that they produce nuclear waste that needs to be buried. However, nuclear waste can be reused for energy production because the uranium that initially goes into energy production gets converted into plutonium, which can then be recycled and used as an energy source. The only problem with this solution there are not many nuclear power plants built in the US and they would have to be built. Nuclear power plants take about 5-10 years to be built. The other problem is that people are afraid of nuclear power and the transportation of radioactive elements.
Small Battery-Powered Drill:
The power generation and supply for building and running the battery-powered screwdrivers is another issue that could be corrected through the use of nuclear power. The use of nuclear power would also reduce the greenhouse emissions from running coal plants. The small battery powered drill requires energy not only to manufacture the product, but also to power the use of the product. 165 million tons of CO2 and 2 million tons of CFCs are released into the atmosphere when 1 million dollars worth of battery-powered drills are manufactured. Then there is also more CO2 and CFCs released when the product is being used (resource 3). 1.57 TJs are produced by coal plants and .351 TJ are produced by natural gas power plants. If nuclear power plants replaced the coal and natural gas plants then the greenhouse gases produced by manufacturing this product would be eliminated.
Ratcheting Screwdriver Parts List
| Part # | Part name | QTY | Function | Wt.(kg.) | Material* | Process* | Photo |
|---|---|---|---|---|---|---|---|
| 001 | Screwdriver Shaft | 1 | Holds the screwdriver bits in its tip, while the base is connected to the handle. | NA | Aluminum | 
| |
| 002 | Screwdriver Handle | 1 | Allows the user to grasp the screwdriver for use. | NA | Rubber/Plastic | 
| |
| 003 | Ring Gear/Ratchet Housing | 1 | Rotates opposite the engaged pawls, and allows for the ratcheting of the screwdriver. | NA | Aluminum | 
| |
| 004 | Pawl | 2 | Engages the ring gear to stop rotation in one direction, allowing rotation in the opposite direction, thereby allowing ratcheting. both pawls can also be engaged to sllow no ratcheting such that the screwdriver can be used as a regular/static screwdriver. | NA | Steel | 
| |
| 005 | Pawl Spring | 2 | The spring pushed the back end of the pawl, forcing it to engage the ring gear. | NA | Aluminum | 
| |
| 006 | Ball Bearing | 1 | Allows free left and right motion of the button. | NA | Aluminum | [] | |
| 007 | Body Screw | 1 | Attaches the screwdriver shaft to the screwdriver handle. | NA | Steel | [] | |
| 008 | Button | 1 | Can be switched left, right, or middle, allowing left or right ratcheting or stopping motion. | NA | Aluminum | 
| |
| 009 | Button spring | 1 | Pushes the ball bearing against the rear of the button. | NA | Aluminum | [] |
Portable Screwdriver/Drill Parts List
| Part # | Part name | QTY | Function | Wt.(kg.) | Material* | Process* | Photo |
|---|---|---|---|---|---|---|---|
| 001 | Screwdriver/Drill Housing | 1 | Houses the internal parts of the drill | NA | Plastic | 
| |
| 002 | Drill Cover | 1 | Covers the nose of the drill | NA | Plastic | 
| |
| 003 | Drill Motor | 1 | Rotates the sun gear, draws current through the wires at the base of the motor to determine the direction and speed of rotation | NA | Plastic/Metals | 
| |
| 004 | Rechargeable Battery Pack | 1 | The power source for the drill, draws power from the battery chargin power input and stores the voltage. | NA | Metal, Plastic, and Chemicals | 
| |
| 005 | O Ring | 1 | Clamps the drill housing to the drill shaft | NA | Metal | 
| |
| 006 | Gear Housing | 1 | Acts as a cylindrical ring gear that houses the planetary gear system. | NA | Copper | 
| |
| 007 | Reset Button | 1 | A button on the external part of the body that will reset the drill when depressed. | NA | Plastic | 
| |
| 008 | Battery Charging Power Input | 1 | Draws voltage from the power cord and send it to the rechargeable battery pack where it is stored. | NA | Plastic/Metal | 
| |
| 009 | Housing Screws | 2x3 | Holds the plastic housing together | NA | Steel | 
| |
| 010 | Trigger | 1 | Switches the direction of the drills rotating output. | NA | Plastic | 
| |
| 011 | Washer | 1 | Keeps the drill motor and gear housing tight together. | NA | Copper |
| |
| 012 | Planetary Gears | 1 | Gears within the gear housing that rotate around the sun gear, they increase the torque by reducing the speed. | NA | Copper | 
| |
| 013 | Sun Gear | 1 | Transfers the rotational output of the motor to the planetary gears. | NA | Copper | 
| |
| 014 | Intermediate Gears | 1 | Keeps smooth rotation between planetary gears and the gear housing. | NA | Copper | 
| |
| 015 | Drill Shaft | 1 | Attached to the output of the gear housing and extends through the drill cover. Holds the drill bit in its external end of the shaft. | NA | Steel | 
| |
| 016 | Lights | 1 | Red, yellow, and green lights that tell when the drill is charged, charging, and needs charging. | NA | Plastic/Metal | 
| |
| 017 | Wiring | 1 | Basic red and black wires running current between electrical parts of the drill | NA | Plastic/Copper | 
| |
| 018 | Switch Box | 1 | Switches the direction of voltage to the motor depending on the direction of triggers depression. | NA | Plastic/Copper | 
|
Mechanical Analysis
Analysis of the Gear Ratio for the Electric Screwdriver:
The electric motor within the electric screwdriver produces a very high rotational speed, but very little torque. However, the customer needs a device capable of producing a relatively high amount of torque, but not necessarily at such a high speed. Thus, the electric motor is geared down before it is attached to the bit. After the dissection of the drill, we found that a planetary gear system was used to accomplish this. In this gear train, the annulus was held stationary within a housing. The sun gear was used for the input, and the output was therefore the planet carrier. This planet carrier in turn was connected to the sun gear for the next level. In total there were three levels of gears, each of which reduced the torque by a factor of 1/(1+A/S), where A is the number of teeth on the annulus, and S is the number of teeth on the sun gear. With three levels, the total gear ratio is 1/(1+A/S)^3.
References
1.http://www.eiolca.net/cgi-bin/multimatrix/display.pl?hybrid=no&key=9232578260&value=3425720201&selectsect=332212&selectvect=gwp&incdemand=1&demandmult=1&top=10&DefSort=1&newmatrix=US491IDOC1997 2.http://www.eiolca.net/cgi-bin/multimatrix/display.pl?hybrid=no&key=9232578260&value=3425720201&selectsect=332212&selectvect=fuels&incdemand=1&demandmult=1&top=10&DefSort=1&newmatrix=US491IDOC1997 3.http://www.eiolca.net/cgi-bin/multimatrix/display.pl?hybrid=no&key=5962855190&value=4772278266&selectsect=333991&selectvect=gwp&incdemand=1&demandmult=1&top=5&DefSort=1&newmatrix=US491IDOC1997 4.http://www.eiolca.net/cgi-bin/multimatrix/display.pl?hybrid=no&key=5962855190&value=4772278266&selectsect=333991&selectvect=fuels&incdemand=1&demandmult=1&top=5&DefSort=1&newmatrix=US491IDOC1997
