Electrodynamic Actuator Magnet System Collar Design
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Solution Overview
Problem
Existing electrodynamic actuators face challenges with poor high frequency response and unwanted lowering of resonance frequency due to the inverse proportional relationship between flux density, magnetic resistance, and the mass of the center magnet system part, which is influenced by the height of the plates.
Innovation Solution
The introduction of a collar on the outer edge of the plates facing away from the center magnet decouples the flux density, magnetic resistance, and maximum operating and excessive excursions from the mass and oscillation behavior of the center magnet system part, thereby improving design freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the height of the plates is reduced to decrease the mass of the center magnet system part, then the high frequency response is improved, but the flux density in the air gap decreases and magnetic resistance increases
Solution Approach 1:
The plate is segmented into two functional zones: a first region that guides magnetic flux and a second region (collar) that defines the air gap height. This segmentation allows the plate to perform multiple functions independently, enabling thin plate design while maintaining adequate flux density through optimized magnetic path geometry in the first region.
Solution Approach 2:
The solution transitions from controlling air gap height through plate thickness (one dimension) to controlling it through the collar structure's vertical extension (another dimension). This dimensional shift allows the main plate body to be thin for high frequency response while the collar provides the necessary air gap definition without adding significant mass.
2Length of moving object
If the height of the plates is increased to increase the maximum operating excursion, then the excursion range is improved, but the mass of the center magnet system part increases leading to poor high frequency response
Solution Approach 1:
The plate's functions are segmented: the first region maintains structural integrity and guides flux, while the second region (collar) specifically controls air gap height and thus maximum excursion. This allows excursion to be increased via collar height without proportionally increasing overall plate mass, as the collar is a localized feature rather than a uniform thickness increase.
Solution Approach 2:
The collar region is given different local properties (increased height) compared to the main plate body. This localized quality change allows the air gap and thus maximum excursion to be increased in the critical region near the voice coil without uniformly increasing the mass of the entire center magnet system part.
3Reliability
If the height of the plates is increased to reduce the maximum excessive excursion, then the protection against damage is improved, but the mass of the center magnet system part increases leading to poor high frequency response
Solution Approach 1:
The collar structure segments the plate's function, allowing it to act as a mechanical stop that defines maximum excursion limits. This localized feature provides protection against excessive movement without requiring a uniform increase in plate thickness throughout, thus limiting the mass increase while maintaining reliability.
4Shape
If the height of the plates is changed to adjust the idle position of the magnetic system, then the position control is improved, but the mass of the center magnet system part changes affecting oscillation behavior
Solution Approach 1:
The plate is segmented into a first region for flux guidance and a second region (collar) for air gap definition. By adjusting the collar's height and position, the idle position of the magnetic system can be controlled without significantly changing the overall mass of the center magnet system part, as the collar is a localized feature.
Solution Approach 2:
The solution moves from controlling idle position through overall plate thickness to controlling it through the collar's vertical dimension. This allows precise position adjustment via the collar structure without proportionally changing the mass of the entire plate assembly.
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 effectively decouples key parameters such as flux density, magnetic resistance, and excursion limits from the mass of the center magnet system, enhancing the high frequency response and reducing the risk of damage from excessive external acceleration.
Implementation Method 1
the magnet system is designed to generate a magnetic field transverse to the conductor in the loop section
Implementation Method 2
the at least one voice coil has an electrical conductor in the shape of loops running around a coil axis in a loop section, and the magnet system is designed to generate a magnetic field transverse to the conductor in the loop section
Implementation Method 3
a spring arrangement, which couples the peripheral magnet system part to the center magnet system part and which allows a relative movement between the peripheral magnet system part and said center magnet system part
Data Source
AI summary
An electrodynamic actuator (2a . . . 2l) is disclosed, which is designed to be connected to a sound emanating structure (3) and which comprises a coil arrangement (4) with at least one voice coil (5, 6) and a magnet system (7a, 7l), comprising an annular peripheral magnet system part (8a, 8l) and a center magnet system part (9a, 9l) with the coil arrangement (4) in-between. Further on, the electrodynamic actuator (2a . . . 2l) comprises a spring arrangement (15), which couples the peripheral magnet system part (8a, 8l) to the center magnet system part (9a, 9l) and allows a relative movement between the same in an excursion direction parallel to a coil axis (C). The center magnet system part (9a, 9l) comprises a center magnet (11) and at least one plate (12a . . . 13l) adjoining said center magnet (9a, 9l) in the excursion direction, wherein the at least one plate (12a . . . 13l) comprises a collar (14a . . . 14l′) on its outer edge, which faces away from the center magnet (11). Additionally, an electrodynamic transducer (1) with such an electrodynamic actuator (1a . . . 1f) is disclosed.