Automotive Fuel Tank Tumbler Drive and Ventilation Systems Design

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Automotive Fuel Tank Tumbler

Drive and Ventilation Systems Design

IDS Engineering

Mark Johnson Spencer Miller

Justin Popp 4/27/2013

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Presentation Overview

• Motivation for Design

• Design Specifications

• Final Design

• Design Methodology

• Compliance Testing

• Project Budget

• Concluding Remarks

• Questions

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Motivation for Design

• Metal tanks corrode over time

• Liquid sealants available

• Continued project

– 2-axis rotating machine - “Tank Tumbler”

• Drive, ventilation and torque overload protection

• Societal impact

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Design Evolution

Previous frame design Modifications performed

Dual Drive Design Motor Platform Slip Clutch Electric Gearmotor NEMA 4 Enclosure Box Stiffening gusset plates Fully modified frame

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Design Specifications: Capacity and

Machine Life Expectations

• Maximum tank size: 16” X 25” X 70”

• Maximum liquid tumbling capacity: 5 gallons

• Lifetime: 250 tanks

• 220VAC 20A single phase power available

• 120 psi compressed air available

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Design Specifications Cont’d

• Maximum main shaft torque: 450 ft-lb

_f

• Variable speed: 2.5-5.0 RPM

• Ventilation flow rate: 0.25 ACFM *

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Final Design: Primary Drive System

ANSI #60 chain 2.75:1 Gearmotor 1hp, 220VAC, 3 phase 35:1 reduction Main machine shaft ANSI #60 chain 3.82:1 Total Reduction:_368:1

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Final Design: Dual Secondary Drive

ANSI #40 chain

Table frame shaft and miter gear drive assemblies on top and bottom (circled)

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Final Design: Safety Shrouds

Completely covers all moving drive components

• OSHA - 1910.212

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Final Design: Ventilation

Fresh air intake from ambient environment Flow path of FLAMMABLE fumes Fumes are evacuated by vacuum created with an aspirator Flow passes through shafts

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Final Design:

Torque Overload Protection

• Ratcheting style slip clutch plates

• Spring force allows torque adjustment

• Alternative designs

Slip clutch disks Spring Tensioning Nut Coil Spring

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Final Design:

Torque Overload Protection Continued

Slip clutch

–

8” length grease access channel

–

Threaded section for spring force adjustment

Unique hexagonal driveshaft

8” length

grease channel threaded

section

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Final Design: Control System

30A breaker VFD provides variable speed capability Controls Indicator lights

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Final Design: Balancing System

Table position is vertically adjustable Adjustable tank mounting brackets Adjustable counter balance weights

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Final Design:

Modifications to Existing Frame

• Add gussets for

increased frame rigidity

• Relocate vertical shaft

bearings to decrease

deflection

• Redesign main shaft

–

Larger, 1.75” dia.

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Mathematical Modeling:

Drive System

• Input torque and power requirement

T=Iα P=Tω

• Chains sized based upon manufacturer procedure

• Shaft models

– Singularity functions: deflections – Von Mises stress

– Fatigue strength:

𝑆𝑆_𝑓𝑓 = (𝑓𝑓 𝑆𝑆_𝑆𝑆𝑢𝑢𝑢𝑢)2

𝑒𝑒 𝑁𝑁

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Mathematical Modeling: Ventilation

Suction required

• Vacuum required to collapse a tank: 𝑃𝑃 = 𝜎𝜎𝑦𝑦𝑦𝑦𝑒𝑒𝑦𝑦𝑦𝑦 𝑢𝑢2

2 𝛽𝛽 𝑤𝑤2 • Major losses: ℎ_{𝐿𝐿 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚} = 𝑓𝑓 𝑙𝑙𝑙𝑙𝑉𝑉2 2𝐷𝐷 • Minor losses: ℎ_{𝐿𝐿 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚} = 1 2 𝐾𝐾𝐿𝐿𝜌𝜌𝑉𝑉2 Aspirator Selection

• Flow rate and pressure requirements

High pressure air

input

Discharge

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Mathematical Modeling: Torque

Overload Protection

• Slip at 160 ft-lb

_f

• Slip disk dimensions and geometry

• Static friction coefficient

• Adjustable mechanism allows for variations

) sin( ) cos( ) cos( ) sin( θ µ θ θ µ θ − + = T Spring RN T F ϴ ϴ Y F_Spring F_Normal F_Friction F_Tangential X

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Compliance Testing:

Primary Chain Tension

• Chain tension measured during acceleration

Primary drive chain Load cell Average Measured Chain Force 134 ± 26 lbf Predicted Chain Force 117 lbf

Predicted chain force within uncertainty range of measured chain force

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Compliance Testing:

Secondary Chain Tension

• Conducted to ensure 50/50 load split

Secondary drive chain Spring-loaded idler sprocket Deflection indicator

Percent of Total Table Load Average Right Side

Chain Tension 30.9 ± 2.3 lbf 40% Average Left Side

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Compliance Testing: Ventilation

Calibration

• Flow rate

– Utilized 90 psi for testing: 0.21 ACFM – Operate with 120 psi: 0.28 ACFM

• Pressure

– Max vacuum pressure before yielding: 0.8 inches H₂O – Maximum internal tank pressure: 0.02 inches H₂O

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Compliance Testing: Slip Clutch Torque

Calibration

• Custom torque wrench

• Digital protractor used to measure angle

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Project Budget

$1000 from Mr. Martinez

+ $500 from NASA Space Grant

$1500 Total

- ($1575) Spent to date

($75) Over budget

*

Engineering and Labor: $34,500 (1500 hours)

Estimated unit production cost: $10,000

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Concluding Remarks

• All design specifications met or exceeded

• Requires protective coating/painting

• Machine ready for field testing and

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Acknowledgements

Mr. Arvin Martinez–Laramie Radiator Works, sponsor

Wyoming NASA Space Grant Consortium, sponsor

Mr. Vince Dauer-University machine shop technician

Mr. Mike Schilt-University machine shop technician

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