Rotor-Bell Cover Plate for Quieter Fan Cooling Airflow
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Solution Overview
Problem
Existing fans with additional cooling air flow through the rotor bell experience increased noise levels due to the additional cooling air flow being fed into the main volume flow.
Innovation Solution
A fan design featuring a cover plate with a radially inclined or curved profile on its outer surface, guiding cooling air flow from the rotor bell into the main volume flow, which includes an overextension and overlap section to manage the airflow direction and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling holes are provided in the rotor bell to enable cooling air flow through the rotor bell, then cooling performance is improved, but noise level increases
Solution Approach 1:
The cover plate acts as an intermediary element between the cooling air flow and the main volume flow. It redirects the cooling air flow in a controlled manner, preventing direct mixing with the main flow that causes noise. The cover plate with its radially inclined outer surface serves as a mediator to manage the interaction between cooling and main air flows.
Solution Approach 2:
The cover plate divides the airflow paths into distinct regions - the cooling air flow path and the main volume flow path. By segmenting the flow paths and controlling their interaction through the inclined cover plate surface, the noise caused by turbulent mixing is reduced while maintaining cooling effectiveness.
2Temperature
If cooling air flow is fed into the main volume flow, then cooling of motor components is achieved, but acoustic performance deteriorates
Solution Approach 1:
The cover plate features a radially inclined outer surface that smoothly redirects the cooling air flow. This curved or inclined surface design prevents abrupt flow changes and turbulence, thereby reducing noise generation while maintaining effective cooling air flow delivery to the main volume flow.
Solution Approach 2:
The cover plate changes the flow direction parameters of the cooling air flow gradually through its inclined surface, rather than abrupt changes. This parameter change in flow direction reduces turbulence and noise while maintaining the cooling function.
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 design effectively reduces fan noise by directing the cooling airflow in a manner that minimizes acoustic disturbances, enhancing airflow management within the fan system.
Implementation Method 1
a radially inwardly extending flow channel to the central opening of the cover plate is formed between the rotor bell base and an inner surface of the cover plate
Implementation Method 2
The cooling airflow is advantageously directed against the outer surface of the cover plate. The cooling airflow can also be directed in the opposite direction, into the rotor bell. This reduces the fan noise caused by the cooling airflow.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a fan (1) comprising a fan wheel (4) with an impeller hub (5) and impeller blades (9), and an electric motor with a stator (17), a rotor (18) rotatable about an axis of rotation (RA), and a rotor bell (15) which has an axially end-face rotor bell base (13), wherein the impeller hub (5) is attached to the rotor bell (15), wherein at least one opening (8) is provided in the rotor bell base (13) to ensure a cooling airflow (55) from the rotor bell (15), wherein the fan (1) further comprises a cover disk (2) arranged on the rotor bell base (13) with a central opening (3), wherein the cover disk (2) at least partially covers the at least one opening (8) of the rotor bell base (13) at axial intervals.such that a radially inwardly extending flow channel (21) to the central opening (3) of the cover disk (2) is formed between the rotor bell base (13) and an inner surface (30) of the cover disk (2), and wherein the cover disk (2) has at least on its outer surface (31) a sloping or curved course radially outward in the direction of the rotor bell base (13).