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Applied Precision Design, LLC Concept Design Review BioMedical Orbital Mixer. Amir Torkaman Applied Precision Design, LLC 1755 East Bayshore Rd. Suite 9B Redwood City, CA 94063 Phone: (650) 387-7902 Fax: (650) 493-1195 www.AprecisionDesign.com. Typical Design Cycle: Biomedical Orbital Mixer.
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Applied Precision Design, LLCConcept Design ReviewBioMedicalOrbital Mixer Amir TorkamanApplied Precision Design, LLC1755 East Bayshore Rd. Suite 9BRedwood City, CA 94063Phone: (650) 387-7902Fax: (650) 493-1195www.AprecisionDesign.com
L T Simplified Energy Model: Energy Entering System CONSERVATION OF ENERGY: Two Modes of Operation: • Cranking Cycle: Energy In = Energy Stored into System • Operating Cycle: Energy Stored = Work Done By System Energy Into System Work Done By System Internal energy (stored) 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)
K m Simplified Energy Model: Energy Stored CONSERVATION OF ENERGY: L T Energy Into System Work Done By System Internal energy W I Energy Stored in the System: Total Energy = Potential + Kinetic Energy Kinetic Energy = ½ Iw^2Potential = 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
L T D (drag) W I F (friction) K m Simplified Energy Model: Energy Leaving System Drag Force = C ~ 0.8 A = .0012 m^2 V = 9.4 m/sec F = .05 N (drag force) Drag Energy = 363 Joules 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
Critical Design Parameters V = r.W Power In = Work / Time = 1.90 Watts (after frictional losses) Drag Power = = 2.02 Watts Centripetal Acceleration = r.W^2 (120g’s) g1 m r Drag Power ~ r^3 Acceleration ~ r Minimize Distance To Center of Mass (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 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% Critical Design Parameters
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 • + REDUCES OVERALL BOX LENGTH FROM 15.75 TO 14.5 • - REQUIRES CLUTCH AND BRAKE TO STOP MOTION OF SPINNER WHILE MIXING • - INTERFERENCE IF CARTRIDGES ARE NOT REMOVED FROM NON-USED MECANISM CONCEPT 1: Separate Mechanisms • + SEPARATE MECHANISMS SIMPLIFY DRIVE • + EASY ACCESS TO CARTRIDGES • - SEPARATE SHAFT AND SUPPORT • - TWO ENCLOSURES REQUIRED
CONCEPT 1CONCENTRIC MIXER/SPINNER PINS IN SLOTS GUIDED IN SLOTS OF POLYMER BEARING
ECCENTRIC DRIVE Orbital Mixer Design ECCENTRIC SHAFT UPPER BEARINGS LOWER BEARINGS TIMING BELT COG
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
Centrifuge Design • Calculated Cartridge G’s
CARTRAGE RETAINER RIBS ON CARTRAGE PREVENT ROTATION SO THAT CAP CAN BE TWISTED IN PLACE
CONCEPT 1 - ARM WITH PIN IN SLOT PREVENTS ROTATION DOES NOT YIELS TRUE ORBITAL MOTION. • CARTIRIDGES NEARIST PIN RESTRICTED IN Y MOVEMENT • CARTRIDGES AWAY FROM PIN EMPHASIXED IN Y MOVEMENT PIN IN SLPT 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. • CARTIRIDGES NEARIST PIN RESTRICTED IN Y MOVEMENT • 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 WITH INDICATOR SIGHT WITHOUT SIGHT CORRECT SPEED OVER SPEED
ELECTRONIC GOVERNOR GENERATOR
COMPARISON OF GOVERNORS MECHANICAL GOVERNOR • - MULTIPLE MOVING PARTS • - DIFICULT TO CALIBRATE • - INDICATOR APPROXIMATE • - DRAG DEPENDENT UPON WIND RESISTANCE ELECTRICAL GOVERNOR • +/- POSSIBLY COUPLED WITH RECHARGABLE BATTERY TO INDICATE CRANK WIND • + ELECTRIC SPEED INDICATOR • + GOOD GOVERNOR SPEED CONTROL • - ADDITION OF MULTIPLE ELECTRICAL COMPONENTS • - COST OF GENERATOR & CIRCUIT BOARD NO GOVERNOR – CENTRIFUGE ACTS AS FLYWHEEL • + ELIMINATES MECHANISN • - DIFFICULT TO BALANCE/CALIBRATE • - NO INDICATOR
3 MINUTE ROTATION STOP PUSH ROD TO RELEASE SPRING LOADED CATCH LEVER GEAR REDUCTION STACK INPUT SPROKET