ElectroMagnetic Actuator – EMA4K Peak Force = 19kN Peak Vel = 4m/sec Typical Damper Pk Performance: 10kN @ 4m/sec Freq response up to 300Hz 200mm stroke All Electric Motion Also avail in 1K, 2K, 6K configurations
Electromagnetic Actuator Fundamentals U-Channel Brushless Linear Servo Motor Consists of a non-contacting forcer coil and a U-channel rare earth (Neodymium) magnet track Ironless forcer means there are no attractive forces and no disturbance forces generated between forcer and magnet track Ironless forcer has low mass resulting in high acceleration forces Three phase coil winding with sinusoidal brushless commutation U-Channel design reduces magnetic flux leakage Non-contact design supported by standard bearings to handle off-axis loading
Electromagnetic Technology – Where Used Assembly Automotive Data Storage Electronic Manufacturing Machine Tool Medical Military/Aerospace Fiber Optics Photovoltaics Packaging Engineered Systems Test & Inspection
Electromagnetic Actuator (EMA) Major Components U-Channel Rare Earth Magnets Optical Encoder Read head with 1um resolution Forcer block attached to 3-phase forcer coils on each side (inside U- channel magnets) Lower T-rail bearing support – 1 each side Drylin actuator shaft bearing with replaceable inserts End of Travel Limit Switches U-Channel Magnet Assembly bolted to column supports both sides Actuator motion generated here
EMA Comparisons – Damper Testing Typical shock absorber performance as obtained from published literature
EMA Comparisons – General Performance Estimates based on the following assumptions: 2500kg GVW, 40kg unsprung, 650kg sprung mass, 6N/mm/sec viscous loading, 50N/mm spring load. Hyd HS = Typical hydraulic actuator with hydrostatic bearings, dual 50l/min servovalves, 200l/min 210 bar hydraulic supply
EMA Comparisons – General Performance Displacement (Pk-Pk) Freq(Hz)Hyd HSEMA4K 1150177 2150177 3143.5177 586.22161 761.33113 1042.6776 2019.7626.3 3011.1612.5 504.64.68 70-- 2.41 150-- 0.53 200-- 0.26 *Peak Acceleration Hyd HSEMA4K 23.1424.25 * = peak acceleration based on unsprung mass of 40kg, wheelpan 20kg, and mass of actuator Actuator Mass Hyd HSEMA4K 25.56kg19kg Estimates based on the following assumptions: 2500GVW, 40kg unsprung, 650kg sprung mass, 6N/mm/sec viscous loading, 50N/mm spring load. Hyd HS = Typical hydraulic actuator with hydrostatic bearings, dual 60l/min servovalves, 200l/min 210 bar hydraulic supply
EMA2K Performance – Road Data Plot of Track Data Command and Feedback Profiles – Direct file Playback (No transfer function compensation required)
EMA2K Performance – Road Data Zoom In on portion of Command AND Feedback Track Data (there are 2 plots)
EMA2K Performance – Road Data Plot of Error throughout Entire Track File (Command – Feedback) RMS Error less than 0.001” (0.025mm)
EMA2K Performance – Road Data Plot of Actual Forces Achieved during dynamic Track Data Playback on EMA2K
EMA2K Performance – Road Data Zoom Plot of Dynamic Force - Track Data
EMA Benefits Summary Higher performance / frequency response due to: No oil column resonance Lower actuator mass Lower friction (no seals) Tighter closed loop control Direct file playback often 10X better than hydraulic system with transfer function compensation! Independent of operating temperature No oil viscosity variables to affect control loop Independent of waveform content Can accurately run low velocity/low force and high velocity/high force without changeover from 2stage to 3stage, etc Independent of accumulator charging/discharging cycles
EMA Benefits Summary Less Maintenance and Downtime No seals, accumulators, servovalves, filtration, oil contamination DryLin bearings only contact points – easily replaceable No system degradation due to component wear (pumps, valves, etc) Modular design and less components makes troubleshooting easier Lower Operating Costs Increased efficiency over servohydraulics means annual electrical operating costs are 30% of comparable hydraulic systems No filters, accumulators, servovalves, seals, hoses, pumps to repair/replace Service and Support fees a fraction of major hydraulic competitors!
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