Segmented Magnetic Air Gap for Loudspeaker Voice Coil Cooling
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Solution Overview
Problem
High power loudspeakers face issues with voice coil temperature elevation leading to reduced efficiency and reliability, and excessive force causing physical damage due to uncontrolled voice coil movement.
Innovation Solution
A high power low frequency transducer design featuring a magnetic structure with an air gap and voice coil, where two magnets with opposite polarities are positioned on either side of a steel disk, and additional steel disks and tubes create top and bottom magnetic gaps to inhibit voice coil movement and enhance air flow for cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air circulation is used to cool the voice coil, then the voice coil temperature is reduced, but the cooling effectiveness is insufficient due to inadequate air flow volume and velocity
Solution Approach 1:
The air gap is segmented into multiple regions (first air gap above the magnet, second air gap below the magnet, and third air gap at the center) to create multiple cooling pathways. This segmentation allows air to flow through different routes, increasing the overall air flow volume and velocity across the voice coil surface, thereby improving cooling effectiveness while maintaining reduced voice coil temperature.
Solution Approach 2:
The invention transitions from a single-plane air gap configuration to a three-dimensional multi-region air gap structure. By positioning magnets and steel disks to create air gaps in multiple spatial dimensions (above, below, and at the center of the magnet), the design enables air to flow through the voice coil from multiple directions simultaneously, significantly enhancing the cooling effect beyond what a single air gap could achieve.
2Power
If the voice coil is subjected to extreme oscillating forces, then the transducer can operate at high power, but the voice coil may oscillate beyond safe movement range causing physical damage
Solution Approach 1:
The invention applies preliminary anti-action by using magnetic fields from strategically positioned magnets to counteract extreme oscillating forces on the voice coil before they can cause damage. The magnets create magnetic gaps that generate restoring forces opposing the voice coil's excessive movement, preventing the coil from oscillating beyond its safe movement range while allowing the transducer to operate at high power levels.
Solution Approach 2:
The invention introduces magnetic fields as an intermediary mechanism between the voice coil and the physical limits of its movement. Rather than allowing direct mechanical contact or uncontrolled oscillation, the magnetic field acts as a mediator that exerts controlling forces on the voice coil, limiting its excursions and preventing physical damage to the transducer components.
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 design effectively limits voice coil movement and temperature, preventing damage while improving cooling efficiency and maintaining reliability and performance.
Implementation Method 1
A high power low frequency transducer having a magnetic structure with an air gap and a voice coil located in the air gap
Implementation Method 2
it provides a straight line air path from top to bottom to allow forced air cooling to remove heat from the voice coil
Data Source
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AI summary
A low frequency transducer arrangement includes a substantially cylindrical structure surrounding a pole piece. The pole piece and the substantially cylindrical structure define a substantially cylindrical air gap therebetween. Two opposite ends of the air gap are both open and separated from each other in an axial direction. A first magnet is disposed in either the pole piece or the substantially cylindrical structure. A second magnet is separated in the axial direction from the first magnet by a middle magnetic gap. The second magnet is disposed in either the pole piece or the substantially cylindrical structure. The first and second magnets provide flux in a same direction in the middle magnetic gap. A top magnetic gap is disposed axially adjacent the first magnet and opposite the middle magnetic gap. A bottom magnetic gap is disposed axially adjacent the second magnet and opposite the middle magnetic gap. A voice coil is at least partially disposed in the air gap and operates in the middle magnetic gap.