Direct Solution

Design review 7-13-2005

Stake Holders

  

Sponsor: Client:

NIATT Karen DenBraven

Customer:

UI CSC 2005-2006 Team, Competition judges, Bob Stephens, Howard Peavy 

Technical Consultant:

Cordon, Phil Arpke Nathan Bradbury, Dan 

Design Team:

Nathan Wasankari, Justin Lanier

Problem summary

 The Clean Snowmobile Challenge strives to produce a snowmobile that is quiet, clean, efficient and has low environmental impact. Traditional transfer of power from the engine to the track involved multiple systems including centrifugal clutches, belts, chains, drive shafts, etc. The CSC 05 06 team has several design focuses for improving the overall sled. One of the major areas for improving sound emission is the drive train between the secondary clutch and the track.

Must vs. Shoulds

          

Must:

Provide a reduction about 2.25:1 for proper power transfer from the secondary clutch to the driven shaft Capable of transmitting 130 hp @ 5000 rpm Life expectancy of 150 hours extending through testing and competition Quieter by at lest 1db in operation than a stock jackshaft and chain case unit Maintain clutch offset alignment with in ± 1/32in Final product will be ready by November 18th for out of sled testing Final product will be installed on the sled for testing by December 1st Conduct sound bench test for frequency and amplitude Perform through out testing and competition with no required maintenance Provide proof through FEA for any chassis modifications to ensure structural integrity   

Should

: Design for Idaho trail riding according to researched rider profiles Be lighter than stock jackshaft and chain case unit

•Third Idler gear drive

Concepts 1,2,3

•Two gear drive •Belt drive

Concept 1 DFMEA highlights

Item and Function Gears Housing Bearings Potential Failure Modes Misalignment Heat Distortion Overloading Potential Effect(s) Of Failure S E V Tooth Shear Gear Contact Excessive Wear 8 9 7 Potential Cause(s) Of Failure Manufacturing Defect 4 Low Oil Level 4 Exceeding Design Loads 3 O C C U R Current Design Controls Measuring Gage D E T E C T 4 128 R P N Manually Check Clear Rating Label 3 4 108 84

Concept 3 DFMEA highlights

Item and Function Potential Failure Modes Drive Belt Drive Shaft Belt Failure Misalignment Drive Belt Deterioration Potential Effect(s) Of Failure S E V Potential Cause(s) Of Failure Loss of Power 8 Operator Error Bearing Wear Belt Failure 7 Improper Installation 8 Age, Chemical Contact O C C U R 3 3 5 Current Design Controls Clear Specifications Installation Instructions Visual Check D E T E C T 5 R P N 120 4 2 84 80

Concept 1 additional research

   Rockwell hardness testing Nitrideing Boston gear Analysis

Concept 3 additional research

 20 pulley diameters available in both 21mm (.9in) and 36mm (1.5in)  Timing belt selection available for 21 and 36mm width for direct drive application Available CMX direct drive on exhaust side

Concept 1 cost estimate

Design concept 1

Design: last years three gear design

Item Nitrideing (estimated) Aluminum stock Bearings (6) Timken

TOTAL

Cost $300.00

$90.00

$250.00

$640.00

Concept 3 cost estimate

Design concept 3

Design: belt drive

Item Pinion pulley Driver pulley Idler pulley Belt Bearings (estimated) Metal stock

TOTAL

Cost $50.00

$100.00

$50.00

$60.00

$125.00

$300.00

$685.00

Concept 1 Pros and Cons

  Pros – Reduced cost by reusing gears from last year – No shipping delay for new gears – Work with last years gear analysis – Work with last years Solid modeling – No modifications to engine performance Cons – Extra rotating mass, in the third gear – More mating surfaces that have to be aligned and toleranced – Size of the system – Increased stress on case

Concept 3 Pros and Cons

  Pros – Smaller system space required – Quieter than comparative gear system – Relatively less required machining time – Relatively less assembly time required Cons – Belt wear – Replacement – Material break down from weather conditions – Deterioration from chemical exposure (gas, oil)

Recommendation

Direct solution recommends solution 3. the direct belt design will meet the client musts and shoulds providing a simple and effective solution to the stated problem.

Audience brainstorming and input

Insights

Unresolved questions

?

Direct Solution

Design review 7-13-2005