EMA Stator Damping via Conductive Rods
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Solution Overview
Problem
Existing electromechanical actuators lack an effective damping mechanism, leading to increased weight, size, and manufacturing costs due to the need for external damper units, which are not present in hydraulic systems.
Innovation Solution
Incorporating nonmagnetic conductive rods or bars into the stator slots of the EMA motor, which are shorted to provide a damping function and act as a mechanical retainer for the windings, allowing for integrated passive damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate damper unit is bolted onto the electric motor, then damping function is achieved, but weight and size of the motor increase
Solution Approach 1:
The patent combines the damping function with the motor structure by integrating conductive bars into the stator slots. These bars serve dual purposes: providing damping through eddy current effects and acting as mechanical retainers for the windings. This merging eliminates the need for a separate damper unit, thereby reducing weight while maintaining the damping function.
Solution Approach 2:
The conductive bars integrated into the stator slots perform multiple functions simultaneously: they provide damping torque through electromagnetic induction and serve as mechanical retainers to hold the windings in place. This multi-functionality replaces what would traditionally require separate components, reducing overall weight and complexity.
2Reliability
If a separate damper unit is bolted onto the electric motor, then damping function is achieved, but manufacturing time and costs increase
Solution Approach 1:
By integrating the damping function into the motor's stator structure through conductive bars, the patent eliminates the need for separate manufacturing and assembly of a damper unit. This reduces manufacturing steps, assembly time, and associated costs while maintaining the damping function.
Solution Approach 2:
The conductive bars serve dual purposes as both damping elements and winding retainers, eliminating the need for separate components. This reduces the total number of parts to manufacture and assemble, thereby reducing manufacturing time and costs.
3Weight of moving object
If conductive rods or bars are incorporated into stator slots, then weight and size are reduced, but damping torque must be optimized through material selection and configuration
Solution Approach 1:
The patent optimizes damping torque by varying parameters such as the material resistivity, dimensions, and configuration of the conductive bars. By adjusting these parameters, the damping characteristics can be tailored to specific application requirements while maintaining a compact and lightweight design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the overall weight and size of the actuator, integrates damping into motor components, and lowers manufacturing costs while maintaining reliability, by generating a drag torque that opposes motor motion, thus preventing undesirable movements like flutter and shimmy.
Implementation Method 1
Eddy-currents are created by the relative motion between the rotating permanent magnets on the rotor, and the stationary conductive bars integrated into the motor stator. The generated currents induce a drag torque, hence a deceleration of motion.
Implementation Method 2
as the rotor magnets rotate, the magnetic flux will induce voltage into the rods or bars
Implementation Method 3
The relative motion between the stator and the rotor will generate a torque which will oppose the useful torque produced by the motor
Data Source
Figure 1A~1B
Figure 2~3
Figure 4A~4C
AI summary
The invention provides a stator for an electric motor comprising a plurality of teeth separated by slots, and comprising conductive material provided in the slots between two or more of the teeth.