Outer Rotor Motor Axial Segmentation for Brake and Sensor Isolation
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Solution Overview
Problem
Conventional servo motors with integrated brakes and sensors face issues such as electromagnetic interference, debris contamination, and mechanical limitations due to the relative positioning of brakes and encoders, leading to performance degradation and undesirable form factors.
Innovation Solution
The electric motor assembly positions the brake assembly axially outward from one side of the rotor core and the sensor axially outward from the opposite side, with a solid rotor core acting as a barrier to prevent debris and electromagnetic interference, allowing for improved protection and reduced contamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the brake assembly and sensor are positioned close together on the same side of the rotor core, then the axial length of the motor is reduced, but the sensor is exposed to electromagnetic interference and debris contamination from the brake
Solution Approach 1:
The motor assembly is segmented into two axial sides: the brake assembly is positioned on one side of the rotor core while the sensor is positioned on the opposite side. This spatial segmentation isolates the sensor from brake-generated interference and debris, allowing both components to function reliably within a compact axial footprint.
2Strength
If the rotor shaft diameter is increased to improve load-carrying capability, then the mechanical strength is improved, but the overall motor size and axial length increase
Solution Approach 1:
The brake assembly is merged with the motor structure by positioning it axially outward from the rotor core on one side, while the sensor is positioned on the opposite side. This integration allows the brake to serve its function without requiring additional axial space, maintaining compact dimensions while supporting adequate load-carrying capability through proper shaft design.
Data Source
AI summary
An electric motor assembly includes an outer rotor motor, a sensor, and a brake assembly. The outer rotor motor includes a stator and a rotor. The rotor at least partly circumscribes the stator and is rotatable relative to the stator about an axis. The rotor includes a rotor core extending radially outwardly to present axially opposite first and second sides, and a plurality of magnets supported relative to the rotor core. The sensor is operable to sense a condition associated with the electric motor assembly. The brake assembly is operably coupled to the rotor core to selectively reduce the rotational speed of the rotor. The brake assembly is positioned at least partly axially outward from the first side of the rotor core, and the sensor is positioned at least partly axially outward from the second side of the rotor core.