Self-Adjusting Fan Gap for Noise and Airflow Trade-off
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Solution Overview
Problem
Fan assemblies in electronic devices generate excessive noise at higher speeds, which is mitigated by increasing the radial gap between impeller blades and housing walls, but this reduces airflow at lower speeds, leading to a trade-off between noise reduction and airflow efficiency.
Innovation Solution
A self-adjusting throat gap is implemented using an insert within the fan assembly that displaces in response to airflow, increasing the gap size at higher speeds to reduce noise and returning to its original size at lower speeds to maintain airflow efficiency, without the need for external controllers or mechanical levers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the radial gap between impeller blades and housing walls is increased to reduce noise at higher fan speeds, then noise levels are reduced, but airflow at lower fan speeds is penalized
Solution Approach 1:
The insert is designed to be movable rather than fixed, allowing it to dynamically adjust its position based on operating conditions. At higher fan speeds, the insert moves to increase the radial gap and reduce noise. At lower fan speeds, it returns to its original position to maintain optimal airflow, thus resolving the contradiction between noise reduction and airflow efficiency across different operating regimes.
Solution Approach 2:
The radial gap parameter is made variable through the movable insert mechanism. The gap size changes based on fan speed and airflow conditions, allowing the system to optimize for noise reduction at high speeds while maintaining airflow efficiency at low speeds. This dynamic parameter adjustment resolves the fixed-gap contradiction.
2Temperature
If the fan runs at higher speeds to cool advanced components, then cooling effectiveness is improved, but noise generation increases
Solution Approach 1:
The movable insert creates a dynamic noise control system that automatically adjusts to fan speed. At high fan speeds required for effective cooling of advanced components, the insert moves to increase the radial gap, thereby reducing the tonal noise that would otherwise be generated. This allows the system to maintain high cooling effectiveness while reducing noise at the speeds when cooling is most needed.
Solution Approach 2:
The high-speed operation that generates both necessary cooling and unwanted noise is transformed into a beneficial condition. The increased airflow at high speeds is used to drive the movable insert, which then reduces the noise generated by that same high-speed operation. The harmful noise is converted into a signal that triggers its own mitigation.
3Object-generated harmful factors
If a fixed large radial gap is used to reduce high-speed noise, then noise is reduced, but airflow efficiency at all speeds is compromised
Solution Approach 1:
Instead of using a fixed large radial gap that compromises airflow at all speeds, the invention employs a movable insert that creates a large gap only when needed at high speeds. At low and medium speeds, the insert maintains its original position, preserving optimal airflow efficiency. This dynamic adjustment eliminates the need for a permanently compromised fixed gap design.
Solution Approach 2:
The insert is self-actuating, using the airflow generated by the fan itself to move the insert to the appropriate position. At high speeds, the airflow drives the insert to increase the gap for noise reduction. At lower speeds, the airflow is insufficient to move the insert, which remains in its optimal position for airflow efficiency. The system serves itself without external control mechanisms.
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 tonal noise while ensuring a minimum airflow threshold, providing improved sound quality and airflow efficiency across varying fan speeds without permanent deformation of the insert.
Implementation Method 1
airflow by the impeller into the gap causes displacement of the insert such that the gap changes from a first size to a second size that is greater than the first size
Implementation Method 2
a decompressed state of the insert may include a separation between the insert and the impeller by a gap having a first dimension... a compressed state of the insert may include the separation between the insert and the impeller increasing to a second dimension of the gap that is greater than the first dimension
Data Source
AI summary
An electronic device with a fan assembly is disclosed. The fan assembly includes an impeller and an insert separated from the impeller by a gap. The fan assembly increases airflow by rotationally driving the impeller. For a sufficient rotational speed of the impeller, the airflow reaches a level that provides a force that displaces the insert. The displacement may include movement and/or compression of the insert. As a result of the displacement, the gap between the impeller and the insert increases. The increased gap reduces the pressure and associated noise that is otherwise caused by the airflow. When the rotational speed of the impeller reduces or ceases, the insert returns to its initial position. In this manner, the fan assembly includes a self-adjusting gap that changes based on the airflow.