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Revision as of 00:20, 11 October 2007

Executive Summary

Updates since Report 1

Please provide any updates to the wiki report on the analysis of our current product (see report 1 revision assignment)

Research and Observations

After interviewing several people and conducting online research (the interviews and key points from the research can be seen in http://ddl.me.cmu.edu/ddwiki/index.php/Windshield_wiper_ideas page ), there were several key problems that came up. From the interviews, the problems we wanted to address were poor winter performance, difficulty in changing the wiper blade, and the desire for a more environmental solution. From research we saw that lack of proper maintenance was an extremely common problem. So we focused on ways to improve the user’s experience in the winter, and on ways to encourage the user to change their blades more often by making the process easier and/or more environmentally sound.

The problem of lack of proper maintenance is twofold: One, people simply don’t remember to change their wipers or are not aware that the wipers need to be changed; two, the difficulty of changing them makes users avoid this task till they can have someone else perform the task. To combat these issues, we have come up with several ideas. Some examples are: to make the rubber of the blades change color like toothbrushes to indicate the need to replace the wiper; to change the latching mechanisms to make it more user friendly; and/or to make wipers where only the rubber need be replaced, and make the rubber attachment point easier to change. The latter option would be more environmentally friendly and would also allow users to buy several rubber pieces at once, making it very easy to change out the rubber piece when ever their visibility is not optimal. Simply changing the latching mechanism on the wiper blades seems promising, but there are simpler latching designs for blades and this would not address the environmental angle. Making the wipers change color seems like a very good idea but would be out of the realm of interest for this project.

To deal with the poor winter performance, we looked at heating the blades and/or adding an extra blade to the assembly. The extra blade would be of a harder material and would scrape the windshield for the user. Adding a heated blade could make this task easier for the wipers to perform.

Top Design Concepts

Please provide sketches and descriptions of your top three to five design concepts, describing what opportunities have been identified and how they will be addressed.

Compressed Air System

The compressed air system is our most revolutionary idea. This system would get rid of the wipers all together. The basic idea of this design is that we would used compressed air to blow the rain off of the windshield. As shown in the figure on the right, several hoses would run of the main air line to nozzles along the bottom of the windshield. When it is raining you would simply turn on the compressed air system and the water would be blown off the windshield. The placement of the nozzles at the bottom of the windshield is effective because it works with the direction of air flow due to the cars movement. A compressor would be stored in the trunk of the car. It would have to be about a 25 gallon compressor, to allow for times of heavy use. Also, in conjunction with the compression system a wax coating, such as Rain-X would be used. This coating causes water to bead and be more easily removed from the windshield.

Durable

Easy to change

Affordable

Effective for all weather

Percentage of windshield covered

Visibility

Heated Blades

Already been done :-( http://www.blizzardblade.com/Place%20Order.htm

http://www.everblades.com/HEATFLEXX.htm -these guys don't have any 'structure', the rubber just fits the curvature of the windshield.

Back of Envelope Calculations They use 12 V * 2.5 Amps = 30 Watts. 2 blades = 60 Watts.

Latent Energy of Fusion = energy to melt ice = 80 calories per gram = 334720 joules per kilogram.

An icy windshield is roughly 6 sqr. feet = .56 Meters Square. 1/4 inch thick = 0.003556 M^3 of ice.

Density of ice = .931 gram/cm^3. Icy windshield = 3560 cm^3. Mass of ice = 3.3 KG of ice on windshield.

Need 3.3 * 334720 = 1,104,576 Joules to melt the windshield.

60 joules/second. = 306 minutes to melt the ice. Wow.

Exchangeable Blades/Rubber

Common Problems affecting wiper blades:

How to change Wiper Blades Just the Rubber part:
Taking them out:
http://www.expertvillage.com/evplayer.aspx?flv=wiper-blade-disassemble
Putting them in:
http://www.expertvillage.com/evplayer.aspx?flv=wiper-blade-assemble

Multiple Blades (flap or rotating)

• top design at this time

• keep current rubber blade for rain

• add blade made out of hard plastic for ice/snow/leaves

• wiper blade subassembly will rotate to change to this setting

• Variation: position hard blade so it can flab down into place

• • the wiper blade subassembly will not need to rotate

• future decisions: angle of hard blade, how to implement rotation

Design Comparisons

Pugh Chart

VOA

also, although the client didn't specifically ask for a VOA, I have asked you to provide one as part of your way of communicating the opportunity.

Gandt Chart

In addition, each report should include a Gantt chart or alternative method to map out the team plan for design and prototyping through the remainder of the semester. Be as detailed and specific to your particular project as you can, and assign roles for team members as appropriate.