Vehicle Loudspeaker Pressure Control via Isolation Valve

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Solution Overview

Problem

Vehicle audio systems face challenges in reproducing low-frequency sound due to practical limitations in speaker enclosure size and the risk of damage from pressure differentials between the vehicle interior and exterior, which can cause sub-optimal performance and permanent damage to the loudspeaker.

Innovation Solution

The implementation of an acoustic conduit with an isolation valve and pressure equalization components that acoustically couple the loudspeaker to both the interior and exterior of the vehicle, allowing for adjustment of the audio signal and isolation from pressure differentials, using a controller to detect conditions and actuate the valve to protect the loudspeaker.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a loudspeaker is coupled to the exterior of the vehicle to act as an infinite baffle, then low frequency sound reproduction is improved, but the loudspeaker is exposed to pressure differentials that may cause damage

Engineering Contradiction:

Improvelow frequency sound reproductionVSAvoidpressure differential damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A pressure equalization port is introduced as an intermediary element that allows pressure to equalize between the interior and exterior of the loudspeaker enclosure. This mediator prevents harmful pressure differentials from developing across the loudspeaker diaphragm while maintaining the acoustic coupling to the exterior for low frequency reproduction.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The enclosure is segmented into distinct pressure zones: the interior passenger compartment, the exterior environment, and the loudspeaker chamber. The pressure equalization port creates a controlled pressure pathway that separates the harmful pressure differential effect from the acoustic radiation function, allowing the loudspeaker to operate in a pressure-balanced environment while still coupling to the exterior for bass reproduction.

Inventive Principle:

Principle #1Segmentation

2Reliability

If sealed enclosures are used for low frequency reproduction, then acoustic performance is improved, but the enclosure volume required is too large for practical vehicular application

Engineering Contradiction:

Improveacoustic performanceVSAvoidenclosure volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The solution transitions from a three-dimensional enclosed volume problem to a two-dimensional pressure equalization problem. By using the pressure equalization port, the system achieves sealed enclosure acoustic performance without requiring the full sealed enclosure volume, effectively using the vehicle's existing interior and exterior spaces as additional acoustic dimensions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Power

If conventional ported box structures are used, then output from the port is improved, but significant enclosure dimensions are required

Engineering Contradiction:

Improveport outputVSAvoidenclosure dimensions

Core Design Contradiction:

PowerVSVolume of stationary object

Solution Approach 1:

The pressure equalization port serves multiple functions simultaneously: it equalizes pressure to protect the loudspeaker, it acts as a radiating element for low frequency sound, and it eliminates the need for a separate large enclosure volume. This multi-functional element replaces the traditional ported box structure's requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 mitigates the effects of pressure differentials, preventing damage and maintaining optimal acoustic performance by adjusting the audio signal and isolating the loudspeaker from harmful pressure differences, ensuring reliable low-frequency sound reproduction.

Implementation Method 1

an acoustic conduit configured to acoustically couple a sound-producing surface of an acoustic transducer

Methodology Applied

Scientific EffectAcoustic coupling: Sound

Implementation Method 2

protecting the loudspeaker from high pressure differentials between the outside atmosphere and inside the vehicle

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 3

a pressure equalizing component configured to equalize pressure between opposing sides of a diaphragm of the acoustic transducer when the isolation valve is actuated

Methodology Applied

Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentUS11661016B2Pressure control in externally ducted loudspeakers

Publication Date: 2023.05.30 DR ING H C F PORSCHE AG

AI summary

A vehicle audio system includes a loudspeaker configured to be acoustically coupled to an interior of a vehicle and to be ducted to an exterior of the vehicle as well as a controller coupled to the loudspeaker. The controller is configured to (i) detect one or more vehicle operating parameters of the vehicle that would result in a pressure differential condition between the interior and the exterior, and (ii) adjust an audio signal provided to the loudspeaker in response to detecting the vehicle operating parameters.