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  • Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    (Magnetische Fluidsteuerung zur Optimierung der Energieeffizienz von MRF-Aktoren)

    Dirk Gth, Jrgen Maas

    Workshop der Nachwuchswissenschaftler im Rahmen der Fachausschusssitzung Unkonventionelle Aktorik

    (23. Oktober 2014)

    Prof. Dr.-Ing. Jrgen Maas

    Ostwestfalen-Lippe University of Applied Sciences

    Control Engineering and Mechatronic Systems

    Liebigstrae 87, Lemgo, Germany

    [email protected], www.motion-ctrl.de

  • (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    Outline

    Introduction and motivation

    Introductions and methodology of MR-fluid control

    Concept for MRF-Clutch System with fluid control Conclusion

    2

  • 1. Introduction and motivation

    Magnetorheological fluids are suspensions of micrometer-sized magnetic

    particles (e.g. carbonyl iron powder) in a carrier fluid, usually a type of oil.

    Carbonyl iron powder particles on a human hair:

    3 (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

  • Carbonyl iron powder particles are suspended in a carrier oil by using additives for

    reducing e.g. the sedimentation processes.

    By applying a magnetic field, these particles form chains in the direction of the

    magnetic flux, which change the yield stress up to 100 kPa of the MRF within

    milliseconds depending on the magnetic flux density.

    1. Introduction and motivation

    Operating mode for

    brakes and clutches

    rotational actuators

    shear mode

    B

    F

    MRF

    4 (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    B=0

    B0

  • 1. Introduction and motivation

    5 (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    axial shear gap:

    particle

    concentration

    due to

    centrifugal forces

    radial shear gap:

    r r

    Axial shear gaps offer:

    Advantages considering particle centrifugation at high rotational speeds due to an

    inherent mixing effect (Taylor vortex flow) and an

    optimized torque generation due to the outside placed shear gap.

    Shear gap design of MRF actuators based on the shear mode

    Gth, D.; Wiehe, A.; Maas, J.: Modeling approach for the particle behavior in MR Fluids between moving surfaces. 12th International

    Conference on Electrorheological (ER) Fluids and Magnetorheological (MR) Suspensions, World Scientific, 2010.

  • 1. Introduction and motivation

    (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    Brakes and clutches based on MRF offer an enormous potential for

    high energy application with high rotational speeds:

    Advanced dissipation of energy in MRF brakes and clutches:

    the scalable volume based energy dissipation in MRF brakes and clutches

    the advanced compensation of thermal load peaks due to a braking fluid volume

    the better dissipation of energy due to an advanced heat conductance

    Challenge opposing a commercial use:

    high rotational speeds can be solved by an adequate design of shear gaps

    viscous torque at high rotational speeds in idle mode

    disadvantageous from an energy point of view of an application e.g. HEV

    needless reduction of lifetime of the MRF

    6

  • (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    1. Introduction and motivation

    MRF-Brake with axial shear gap for high rotational speeds up to 6.000 min-1

    B

    shear gap

    electromagnet

    shaft

    seal

    housing

    magnetic circuit

    bearing

    rotor

    Dimensions of shear gap:

    mean radius r = 41mm, height h = 3mm, length l = 40mm, volume VMRF = 32ml.

    7

    Gth, D.; Wiebe, A.; Maas, J.: Design of Shear Gaps for High-Speed and High-Load MRF Brakes and Clutches. 13th International Conference

    on Electrorheological (ER) Fluids and Magnetorheological (MR) Suspensions, Journal of Physics: Conference Series, 2013, 412, 012046.

  • (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    1. Introduction and motivation

    MRF-Brake with an axial shear gap for high rotational speeds

    0 1 2 3 4 50

    5

    10

    15

    20

    25

    30

    current I in A

    torq

    ue T

    in

    Nm

    n=500 min-1

    n=2000 min-1

    n=3000 min-1

    n=5000 min-1

    n=6000 min-1

    Measurements showing control characteristic lines for different rotational speeds at = 50

    Discussion:

    MRF brakes for applications

    with high rotational speeds

    can be realized

    reproducible braking torque

    even at high rotational

    speeds

    high viscous torque at high

    rotational speed n (without

    excitation, (I = 0A)

    temperature depending

    torque behavior needs to be

    considered

    Necessary conclusion:

    approach for reducing the viscous idle torque of MRF brakes and clutches

    8

    Gth, D.; Erbis, V.; Schamoni, M.; Maas, J.: Design and characteristics of MRF-based actuators for torque transmission under influence of high

    shear rates up to 34,000 1/s. SPIE Smart Structures/NDE, Volume 9057, 90572P, 2014.

  • 2. Simple concepts of MR-fluid control induced by force fields

    9 (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    Shear gap volume are not completely filled with MRF for enabling a movement of the fluid.

    Use of different force effects like gravitational (orientation), centrifugal (rotation) and magnetic

    forces for moving the MRF to achieve an engaged or disengaged mode.

    US patent application, US 7,306,083, Magnetorheological fluid device, GM Global Technology Operations, 2005)

    Patent application, Magnetic Fluid Control, 10 2011 119 919.9, Ostwestfalen-Lippe University of Applied Sciences, Germany, 2011.

    use of gravitational force for

    disengagement and magnetic

    forces for engagement

    Dis

    en

    ga

    ge

    d

    mo

    de

    s

    En

    ga

    ge

    d

    mo

    de

    s

    use of centrifugal force for

    disengagement and magnetic

    forces for engagement

  • 2. Basic design concept of MR-fluid control

    10 (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    MRF movement between an active and inactive shear gap.

    Energy input and idle losses can be reduced or at best completely avoided.

    Advanced concept for complete disengagement during rotation and standstill.

    Integration of a permanent magnet for achieving states like a current less braking torque.

    Half section of the magnetically induced fluid control approach with a partially filled gap.

    permanent

    magnet

    active

    shearing gap

    inactive

    shearing gap

    electromagnet

    shaft

    flange

    seal

    magnetic circuit

    housing

    Gth, D.; Maas, J.: MRF actuators with reduced no-load losses. SPIE Smart Structures/NDE, Vol. 8341, S. 834121, 2012.

  • 2. Basic design concept of MR-fluid control

    11 (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    Motion of the MRF is induced by a controlled leading of the magnetic flux resulting in

    magnetic force acting on the MRF.

    MRF can be switched between an active and inactive volume of the shear gap.

    b)

    transition between

    braking/coupling and

    idle mode

    idle mode braking/coupling

    Gth, D.; Schamoni, M.; Maas, J.: Magnetic fluid control for viscous loss reduction of high-speed MRF brakes and clutches with well-

    defined fail-safe behavior. Smart Materials and Structures, Vol. 22, 094010, 2013.

  • (C) Control Engineering and Mechatronic Systems - Prof. Dr.-Ing. Jrgen Maas, Dirk Gth Magnetic Fluid Control for Optimizing the Energy Efficiency for MRF-Actuators

    2. Design methodology for MR-fluid control

    12

    - current direction is moving into the page

    - current direction is moving up out of the page

    torque transmission region

    inactive region i - inside EM

    o - outside EM

    polarity of the PM

    electromagnet (EM)

    r = 0

    r >> 0

    disengaged disengaged disengaged (Fig. 4)

    (Fig. 2/5)

    Gth, D.; Schamoni, M.; Maas, J.: Magnetic fluid control for viscous loss reduction of high-speed MRF brakes and clutches with well-

    defined fail-safe behavior