Voice Coil Bobbin Composite Thermal Dissipation

Solution Overview

Problem

In loudspeakers, most electrical energy is converted to heat rather than acoustic energy, limiting acoustic output without increasing the number of transducers, and improving efficiency reduces low-frequency range.

Innovation Solution

A high-power voice coil design featuring a bobbin with a non-conductive material infused with high-temperature adhesive, a thermally-conductive material layer, and a conductive wire, which enhances thermal dissipation and dimensional stability while maintaining frequency range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the voice coil operates at higher power to increase acoustic output, then the acoustic energy output increases, but the thermal energy generated increases causing the voice coil temperature to exceed material limits

Engineering Contradiction:

Improveacoustic output powerVSAvoidvoice coil temperature

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The voice coil former is constructed as a composite structure with an inner core of thermally conductive material (aluminum or copper) surrounded by an outer layer of dimensionally stable non-conductive material (fiberglass or Nomex). This composite design allows the inner core to efficiently conduct heat away from the voice coil windings while the outer layer maintains dimensional stability and electrical insulation, enabling higher power operation without exceeding material temperature limits.

Inventive Principle:

Principle #40Composite materials

2Power

If the transducer efficiency is increased to get higher acoustic output, then the acoustic energy output increases, but the low frequency output capability is reduced

Engineering Contradiction:

Improveacoustic output powerVSAvoidfrequency range

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The invention changes the thermal and mechanical parameters of the voice coil former by using a thermally conductive inner core material with high thermal conductivity and appropriate mechanical properties. This parameter change allows the voice coil to operate at higher temperatures without degradation, enabling higher power output across the entire frequency range including low frequencies, without the efficiency-frequency range trade-off that plagues conventional designs.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If conventional voice coil materials are used to maintain dimensional stability, then the structural integrity is maintained, but thermal dissipation capability is insufficient

Engineering Contradiction:

Improvedimensional stabilityVSAvoidthermal energy dissipation

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The voice coil former is constructed as a composite structure with an inner core of thermally conductive material (aluminum or copper) surrounded by an outer layer of dimensionally stable non-conductive material (fiberglass or Nomex). This composite design allows the inner core to efficiently conduct heat away from the voice coil windings while the outer layer maintains dimensional stability and electrical insulation, enabling higher power operation without exceeding material temperature limits.

Inventive Principle:

Principle #40Composite materials

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

The solution allows for increased acoustic output and operational power without compromising frequency range or causing dimensional instability, thereby improving loudspeaker efficiency and reliability.

Implementation Method 1

a layer of thermally-conductive material located in between the first layer of a non-conductive material and the second layer of a non-conductive substance

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a first layer of a non-conductive material infused with a high-temperature adhesive, a second layer of a non-conductive material infused with a high temperature adhesive

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11323819B2High power voice coil

Publication Date: 2022.05.03 ROBERT BOSCH GMBH

AI summary

A voice coil for use with a loudspeaker. The voice coil includes a bobbin that has a first layer of a non-conductive material infused with a high-temperature adhesive, a second layer of a non-conductive material infused with a high-temperature adhesive, and a layer of thermally-conductive material located in between the first layer of a non-conductive material and the second layer of a non-conductive substance, and a conductive wire wrapped around the bobbin.