Applied Precision Design, LLC Concept Design Review BioMedical Orbital Mixer

Applied Precision DesignAmir Torkaman • ENGR10 • Fa13

Applied Precision Design, LLCConcept Design Review

BioMedical Orbital Mixer

Amir Torkaman

Applied Precision Design, LLC1755 East Bayshore Rd. Suite 9B

Redwood City, CA 94063Phone: (650) 387-7902

Fax: (650) 493-1195

www.AprecisionDesign.com


Typical Design Cycle: Biomedical Orbital Mixer

VIDEO


Simplified Energy Model: Energy Entering System

Energy Into the System:

Energy Into System = Human Power

Work = Τ∆Θ example: T = 2.25Nm L = 75mm

∆Θ = 30 Turns X 2Π = 188.4 rad W = 423.9 J

Independent of Crank Time or Speed (30 sec)

CONSERVATION OF ENERGY:

Internal energy (stored)

Work Done By System

Energy Into System

Two Modes of Operation:1. Cranking Cycle: Energy In = Energy Stored into System2. Operating Cycle: Energy Stored = Work Done By System

T

L


Simplified Energy Model: Energy Stored

Energy Stored in the System:

Total Energy = Potential + Kinetic Energy

Kinetic Energy = ½ Iw^2 Potential = m.g.∆h Spring = ½ K ∆Θ^2

m = 5 grams (x4) m = 5 grams (x4) k ~ 23 N-mm / rad d = 50mm g= 9.8 m/sec^2 ∆Θ = turns x 2Π I = 50e-6 Kg/m^2 ∆h = 30mm Spring E = varies with time Kinetic E = 0.88 J Potential E = 0.005 J

CONSERVATION OF ENERGY:

Internal energy

Work Done By System

Energy Into System

T

L

mK W

I


Simplified Energy Model: Energy Leaving System

Energy Out of the System:

Total Work = Frictional Losses + Drag

Frictional Losses = Σ (ζ.E + μ.N.d.∆Θ) ζ = 3-5 % (gear efficiency)

μ = 0.2 (sliding bearing friction)Total Energy Loss ~ 80 Joules

T

L

mK W

ID (drag)

F (friction)

Drag Force =

C ~ 0.8 A = .0012 m^2 V = 9.4 m/sec F = .05 N (drag force) Drag Energy = 363 Joules


Power In = Work / Time = 1.90 Watts (after frictional losses)

Drag Power = = 2.02 Watts

Centripetal Acceleration = r.W^2 (120g’s)

Critical Design ParametersV = r.W

r

EXPERIMENTS

Increase Air Resistance(Thru addition of a thin sheet metal foil)Significant reduction in final velocity

Increase Mass 5g 10g(Same max speed / took longer to get to speed

Increase Mass 5g –> 15g(no change in Steady-State conditions) vibration and rattling, more force on bearings

Reduce # of Cartridges Increase of Cartridge Length

m

Critical Design Parameters

g1

Minimize Distance To Center of Mass (r)

Air Drag Coefficient < 0.4

Use Rolling Bearing μ < 0.01

Reduce # of Gears / Belts / & provide Good Alignment

Reduce Moving Mass / Inertia

Improve Gear Efficiency Thru Lubrication ζ < 3%

Drag Power ~ r^3Acceleration ~ r


Mixer Design

Design Goals Top loading Cartridge top twist in holder Low power loss

Ball bearings Minimize CG dia.

Mixer: 2mm orbital diameter Centrifuge: 1800 RPM


COMPARISON CONCEPT 1 - CONCEPT 2

CONCEPT 2: Combined Mixer / Centrifuge

1. + REDUCES OVERALL BOX LENGTH FROM 15.75 TO 14.5

2. - REQUIRES CLUTCH AND BRAKE TO STOP MOTION OF SPINNER WHILE MIXING

3. - INTERFERENCE IF CARTRIDGES ARE NOT REMOVED FROM NON-USED MECANISM

CONCEPT 1: Separate Mechanisms

1. + SEPARATE MECHANISMS SIMPLIFY DRIVE 2. + EASY ACCESS TO CARTRIDGES3. - SEPARATE SHAFT AND SUPPORT4. - TWO ENCLOSURES REQUIRED


CONCEPT 1CONCENTRIC MIXER/SPINNER


PINS IN SLOTS GUIDED IN SLOTS OF POLYMER BEARING

CONCEPT 1CONCENTRIC MIXER/SPINNER


CONCEPT 2SEPARATE MIXER/SPINNER ASSEMBLY

TOP VIEW

15.75”

9”


ECCENTRIC DRIVE

ECCENTRIC SHAFT

UPPER BEARINGS

TIMING BELT COGLOWER BEARINGS

Orbital Mixer Design


Centrifuge Design

Design Goals Top loading Low power loss

Ball bearings Minimize CG dia. Aerodynamic Holders

G1 > 50G G2 ~ 120G G-load axial to cartridge Contain Blood Spill


CONCEPTCONCENTRIC MIXER/SPINNER


DETAL DESIGN


CONCEPT SEPARATE MIXER/SPINNER ASSEMBLY


Typical Design Cycle: Biomedical Orbital Mixer

VIDEO


BACK UP SLIDES


CONCEPTSEPARATE MIXER/SPINNER ASSEMBLY

FRONT VIEW

7.75”


Centrifuge Design

Calculated Cartridge G’s


RIBS ON CARTRAGE PREVENT ROTATION SO THAT CAP CAN BE TWISTED IN PLACE

CARTRAGE RETAINER


CONCEPT 1 - ARM WITH PIN IN SLOT PREVENTS ROTATION

PIN IN SLPT

DOES NOT YIELS TRUE ORBITAL MOTION. CARTIRIDGES NEARIST PIN

RESTRICTED IN Y MOVEMENT CARTRIDGES AWAY FROM PIN

EMPHASIXED IN Y MOVEMENT

Y

X


CONCEPT 2 - SPRING ROTATION PREVENTER

4X SPRING POST SPRING NOT SHOWN


COMPARISON OF MIXER ANTI-ROTATION DEVICES

ARM IN SLOT - DOES NOT YIELD TRUE ORBITAL MOTION.

1. CARTIRIDGES NEARIST PIN RESTRICTED IN Y MOVEMENT2. CARTRIDGES AWAY FROM PIN EMPHASIXED IN Y MOVEMENT

+ Simple Design - FRICTION

SPRING - SPRINGS PRONE TO BREAKAGE - UNKNOWN HARMONICS + LOW FRICTION - NOT GOOD WITH CAP TWIST + Simple Design

SWASH PLATE + ROBUST DESIGN - FRICTION


MECHANICAL GOVERNOR WITH SPEED INDICATOR

GOVERNOR


MECHANICAL GOVERNOR WITH SPEED INDICATOR

WITHOUT SIGHT

CORRECT SPEED

OVER SPEED

WITH INDICATOR SIGHT


ELECTRONIC GOVERNOR

GENERATOR


COMPARISON OF GOVERNORS

MECHANICAL GOVERNOR1. - MULTIPLE MOVING PARTS2. - DIFICULT TO CALIBRATE3. - INDICATOR APPROXIMATE4. - DRAG DEPENDENT UPON WIND RESISTANCE

ELECTRICAL GOVERNOR5. +/- POSSIBLY COUPLED WITH RECHARGABLE BATTERY TO INDICATE CRANK

WIND6. + ELECTRIC SPEED INDICATOR7. + GOOD GOVERNOR SPEED CONTROL8. - ADDITION OF MULTIPLE ELECTRICAL COMPONENTS9. - COST OF GENERATOR & CIRCUIT BOARD

NO GOVERNOR – CENTRIFUGE ACTS AS FLYWHEEL10. + ELIMINATES MECHANISN11. - DIFFICULT TO BALANCE/CALIBRATE12. - NO INDICATOR


3 MINUTE ROTATION STOP

PUSH ROD TO RELEASE

SPRING LOADED CATCH LEVER GEAR REDUCTION STACK

INPUT SPROKET

Applied Precision Design, LLC Concept Design Review BioMedical Orbital Mixer

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