HVAC Double Wall Noise Attenuation Structure

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Solution Overview

Problem

HVAC systems in vehicles generate undesirable noise during the recirculation mode, which is magnified by turbulent air flow and air flaps, and existing solutions are limited by packaging and cost constraints.

Innovation Solution

A double wall noise attenuation structure is integrated into the HVAC system's housing, extending outward from the outer surface to the noise path, comprising a first and second wall spaced apart, with optional ribs and noise barriers to effectively dissipate noise before it reaches the passenger compartment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a double wall noise attenuation structure is added to the HVAC system housing, then noise transmission to the passenger compartment is reduced, but device complexity and packaging space requirements increase

Engineering Contradiction:

Improvenoise transmissionVSAvoidhousing structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The housing is segmented into multiple walls (first wall and second wall) spaced apart from each other, creating a double wall structure that interrupts noise transmission paths. This segmentation divides the single housing structure into multiple components that work together to attenuate noise while maintaining functional requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The double wall structure is integrated within the existing HVAC housing boundaries, with the first and second walls nested within the housing structure. This nesting approach allows the noise attenuation structure to be incorporated without significantly increasing external dimensions or compromising packaging space.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Object-affected harmful factors

If the double wall structure extends outward from the housing outer surface to the noise path, then noise attenuation effectiveness is improved, but the available packaging space in the vehicle is reduced

Engineering Contradiction:

Improvenoise attenuation effectivenessVSAvoidavailable packaging space

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The double wall structure extends outward only in specific locations where noise transmission paths are identified, rather than uniformly across the entire housing surface. This localized extension approach provides effective noise attenuation at critical noise paths while minimizing the overall impact on packaging space and vehicle interior volume.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If a double wall structure with spaced walls is implemented, then noise dissipation is improved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvenoise dissipationVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The first wall and second wall of the double wall structure are integrated as part of a unified housing assembly, combining noise attenuation functionality with the existing housing structure. This merging approach allows the spaced walls to be manufactured and assembled together, reducing overall manufacturing complexity compared to adding a completely separate noise attenuation component.

Inventive Principle:

Principle #5Merging (Combining)

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 double wall structure significantly reduces noise transmission from the HVAC system to the passenger compartment, maintaining comfort while adhering to vehicle package requirements and cost efficiency.

Implementation Method 1

The double wall structure is configured to extend outwardly from an outer surface of the housing to a noise path of the heating, ventilating, and air conditioning system. The double wall structure has a first wall and a second wall spaced from the first wall.

Methodology Applied

Scientific EffectSound absorption: Acoustic Absorption

Implementation Method 2

a double wall structure within a direction of noise traveling from an HVAC system to a passenger compartment of the vehicle, wherein the double wall structure minimizes the noise traveling from the HVAC system

Methodology Applied

Scientific EffectSound reflection: Reflection

Data Source

PatentUS20200324618A1Noise attenuation double walls for HVAC recirculation noise reflecting off windshield

Publication Date: 2020.10.15 HANON SYST CO LTD

AI summary

A noise attenuation structure of a housing of a heating, ventilating, and air conditioning system of a vehicle includes a double wall structure. The double wall structure is configured to extend outwardly from an outer surface of the housing to a noise path of the heating, ventilating, and air conditioning system. The double wall structure has a first wall and a second wall spaced from the first wall.