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3-2018 Magnetically Geared Lead Screw

Mojtaba Bahrami Kouhshahi Portland State University

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Citation Details Kouhshahi, Mojtaba Bahrami, "Magnetically Geared Lead Screw" (2018). Electrical and Computer Engineering PhD Day. 4. https://pdxscholar.library.pdx.edu/ece_phd_day/4

This Poster is brought to you for free and open access. It has been accepted for inclusion in Electrical and Computer Engineering PhD Day by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Magnetically Geared Lead Screw

Mojtaba Bahrami Kouhshahi, Jonathan Bird

Linear actuation is often achieved through a hydraulic, pneumatic, or Introduction Inner translator mechanical mechanism. These, however, suffer from: pi pole-pairs  Based on the magnetic (1) Central ferromagnetic rings fieldmodulation  Large, bulky and loud air compressor nt pole-pieces (2)  3concentricparts  Likely to leak (3)  Linear motion speed  Low efficiency change Outer translator  Regular maintenance  No physicalcontact po pole-pairs

 Reliability issue Linear Magnetic Gear (LMG) Magnetic nut  Analogous to mechanical  Noise (Helical) nut and screw Problem Statement  Rotary motion to linear An example of magnetic field modulation motion  Low force per kg of magnets in long stroke length  Magnetic screw No physical contact  Costly to build (Helical) (4)

Proposed Magnetically Magnetic Lead Screw (MLS) (5) Geared Lead Screw (MGLS) i y t w wo w Prototype 1 Issues  Ferromagneticlongstroketranslator Outer cylinder θ  3concentricparts Annular skewed r z  Skewed translator rings are relatively hard and expensive to manufacture translator  High speed rotary motion to low speed linear  Small tolerance inaccuracies in the rings results in significant force reduction motion λi  Highforceperkg of magnetmaterials Prototype 2  Inherentlyoverloadprotected Helical skewed Skewed translator Outer cylinder L (c) inner rotor (a) (b) x

(6)

Axial displacement, La, of half rings [mm] La a) Parametric design to investigate the effect of the axial shift, La, between the top and bottom set of half rings (b) Maximum translator force versus, (c) proposed new MGLS (a) (b) (a) (b)

a) Force and b) torque on each MGLS part Radial flux density in the outer airgap due to inner rotor Prototype 1 magnets. b) Harmonic content with translator present (a) (b) Inner rotor Outer cylinder (a) (b)

Radial flux density in the inner airgap due to outer cylinder Measured and calculated translator force magnets. b) Harmonic content with translator presents Radial flux density along z-axis at radial distance of (a) (b) 0.85mm from the surface of the a) inner rotor and b)

outer cylinder wt wg

Close up view of the translator pole-pieces and wg space between plastic (black) and steel rings (gray). Variation of the force as a function of wg Translator a) Force and b) torque on each MGLS part Outer cylinder Translator Translator Obstacle Load cell Translator Load cell  Translator rings are not skewed  Cost of fabrication is lower Servo motor MGLS Electromechanical actuator Obstacle

Translator force measurement MGLS on test bed Translator Outer cylinder Translator force measurement