Dynamic Response High Torque Density External Rotor Frameless Torque Motor

●  Introduction

The external rotor frameless torque motor is a specialized type of permanent magnet synchronous motor (PMSM) composed of two core components: the rotor and stator. Unlike traditional internal rotor designs, this motor features an externally mounted rotor and an internally positioned stator. The innovative design eliminates traditional motor housings, bearings, and shafts, retaining only the rotor and stator assemblies. The rotor, located outside the stator, integrates permanent magnets with the outer shell and is directly embedded into the load structure. The stator, positioned internally, contains copper windings and laminations, driving the external rotor’s rotation via electromagnetic forces. This design combines the high moment of inertia of the external rotor configuration with the compactness of the frameless structure, making it ideal for applications requiring low-speed high-torque output and efficient heat dissipation, such as medical equipment, industrial fans, and automated industrial systems.
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Features

● Optimized External Rotor Structure

  • Rotor and shell are integrated, enabling higher moment of inertia through external rotation, improving low-speed stability and heat dissipation (heat is rapidly conducted through the shell).

  • Internally positioned stator minimizes electromagnetic interference on the load, ensuring precision in sensitive control scenarios.


● High Torque Density and Efficiency

  • Utilizes multi-pole permanent magnet layouts and vacuum potting technology, increasing torque density by 20%-30% compared to conventional motors, delivering higher torque per unit volume.

  • Reduces mechanical transmission losses, improving energy transfer efficiency by 10%-15% and lowering iron/copper losses.


● Dynamic Response and Precision

  • Directly drives loads, eliminating backlash from gears/belts, boosting response speed by 25%-40%, and achieving micrometer-level positioning accuracy.

  • External rotor structure supports low-speed high-torque output, ideal for smooth operation and precision-critical applications.


● Enhanced Heat Dissipation and Lightweight Design

  • Direct contact between the external rotor and shell, combined with high thermal conductivity materials, improves heat dissipation efficiency by 20%-30% and reduces temperature rise by 15%-25%.

  • Removal of redundant frames reduces weight by 30%-50%, making it suitable for weight-sensitive applications like aircraft or mobile robots.


● Customizable Integration Flexibility

  • Supports parameter customization (rotor dimensions, magnetic waveforms) for seamless embedding into mechanical structures, meeting diverse design requirements.

  • Modular design simplifies maintenance and reduces integration complexity.


● Quiet Operation and Low Maintenance Costs

  • No mechanical transmission friction, operating at sound pressure levels below 50dB.

  • Simplified structure reduces wear-prone components, lowering maintenance frequency by 60%-80%.

Specification

Sheet 1

ParametersUnitWK1105WK1806WK2205WK2806WK3505WK3510WK4310WK4315WK5215WK5225WK5515WK6010WK6025WK8110WK8115HWK81105LWK10025
Nominal voltageV1212121212122424242424242424242436
Nominal currentA0.590.660.660.811.10.530.90.591.121.281.61.37.41.75175.63.8
Nominal torqueN.M0.010.030.040.060.090.110.20.280.761.260.650.81.771.62.161.74
Nominal SpeedRPM8508007929504673635042382212212642945041301800450168
Max SpeedRPM18057501756302335161096510286607906125595647202902280600300
Stall torqueN.M0.010.060.060.090.150.160.490.421.151.91.261.592.68233.58.5
Stall currentA0.92111.221.90.81.9091.691.943.22.710.67324816
Winding turns of motorT504565604040606060504280303083020
Phase resitanceΩ12.55.9856.348.810.32211811.85.7710.583.530.13.73
Phase inductancemH1.151.31.451.511.083.953.266.567.811.313.827.3610.0731.50.22.32.23
Speed constantrpm/v1083951001211174534.423141423.315.520114712.59.5
Torque constantN.M/A0.010.060.060.070.080.20.230.470.680.980.430.610.231.130.1250.31.03
Rotor inertiagcm^215401251568120226866793374674816452860150015004656
Number of pole pairsPairs67771111.001414111114141421212121
Motor weightg612122224/3236/4778110167281196156345206313131576
Working temperature°C-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80-20~80
Max demagnetize temperature°C120120120120120120120120120120120120120120120120120
Table data is for reference only