HVAC Blower Switching Door Ribs and Perforated Panel Noise Suppression
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Solution Overview
Problem
HVAC systems in vehicles generate noise during operation, which affects occupant comfort and enjoyment, and existing solutions fail to effectively reduce noise while maintaining airflow characteristics.
Innovation Solution
The blower unit incorporates a switching door with a plurality of ribs and perforated panels, strategically positioned to suppress noise by utilizing different distances between ribs and extending perforated panels to align with airflow, achieving phase cancellation of target tones during air introduction modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional blower units are used without noise suppression structures, then airflow characteristics are maintained, but noise levels in the passenger compartment are high
Solution Approach 1:
The switching door is segmented with multiple ribs (first rib, second rib, third rib) spaced at different distances to create multiple phase cancellation zones. This segmentation allows the noise suppressor to target different frequency components of the blower noise while maintaining airflow paths between the ribs, thus resolving the contradiction between noise reduction and airflow maintenance
Solution Approach 2:
Perforated panels are introduced as intermediary elements between the ribs and the airflow path. These panels provide acoustic impedance to cancel noise phases while their perforated structure allows air to pass through, serving as a mediator that simultaneously addresses noise suppression and airflow requirements
2Object-affected harmful factors
If noise suppression structures are added to the blower unit, then noise levels are reduced, but device complexity increases
Solution Approach 1:
The noise suppression functionality is merged directly into the switching door assembly by integrating ribs and perforated panels into the door structure itself. This eliminates the need for separate noise suppression components, reducing overall device complexity while achieving effective noise reduction
Solution Approach 2:
The switching door serves multiple functions: it controls air intake sources (inside/outside air switching) and simultaneously acts as a noise suppressor through its integrated ribs and perforated panels. This multi-functionality reduces the need for additional components, thereby reducing device complexity while addressing noise issues
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 effectively reduces noise levels in the passenger compartment by canceling out objectionable tones through phase interference, maintaining airflow uniformity and improving overall system performance.
Implementation Method 1
The first plurality of ribs and the first perforated panel reduce noise generated during an inside air introduction mode. During the inside air introduction mode, air from inside the passenger compartment is introduced to the inside/outside air switching box.
Data Source
AI summary
A blower unit for a heating, ventilation, and air conditioner system (HVAC) of a vehicle. The blower unit includes an inside/outside air switching box. A switching door disposed in the inside/outside air switching box that is configured to selectively open and close an inside air introduction port and an outside air introduction port of the inside/outside air switching box. A fan is also located inside the inside/outside air switching box and blows air introduced into the inside/outside air switching box from the inside air introduction port and the outside air introduction port into the passenger compartment. A first plurality of ribs is provided on an inner surface of the switching door with a first perforated panel coupled to each of the first plurality of ribs. The first plurality of ribs and the first perforated panel reduce noise generated during an inside air introduction mode.