Double-Flow Fan Nozzle Design for Electric Machine Noise Reduction
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Solution Overview
Problem
Electrical machines experience noise emissions due to fan operation, which can be annoying and affect efficiency, particularly in high-speed applications where noise increases with impeller size and speed, and axial or radial fans face limitations in volume flow and pressure generation.
Innovation Solution
A double-flow fan design with two opposing air inlet openings configured as nozzles, potentially accompanied by a soundproofing wall and a diffuser area, to improve airflow efficiency and reduce noise, and the fan is driven directly by the rotor shaft for self-ventilation, eliminating the need for a separate drive unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the impeller diameter is increased to improve volume flow, then the cooling capacity is enhanced, but the noise emissions increase and the impeller cannot be operated at high speeds
Solution Approach 1:
The single air inlet opening is segmented into two opposing air inlet openings, creating a double-flow configuration. This segmentation allows the impeller to draw air from both sides simultaneously, effectively doubling the volume flow capacity without increasing the impeller diameter, thereby maintaining compact size and reducing noise emissions while enhancing cooling capacity
Solution Approach 2:
The invention transitions from a single-sided air intake (one-dimensional flow path) to a dual-sided air intake (two-dimensional flow pattern). By positioning air inlet openings at opposing locations around the impeller circumference and configuring them as nozzles, the system exploits spatial dimensionality to increase airflow capacity without proportionally increasing impeller size, thus avoiding the noise and speed limitations associated with larger single-sided impellers
2Stress or pressure
If the impeller diameter is increased to generate higher pressure, then the cooling efficiency is improved, but the noise emissions increase and device complexity increases
Solution Approach 1:
The pressure generation function is segmented across two opposing air inlet openings with nozzle configurations. Each nozzle is optimized to generate sufficient pressure on its respective side, and the combined effect achieves the required total pressure without requiring a larger single impeller diameter, thereby maintaining lower noise emissions
Solution Approach 2:
The invention changes the geometric parameters of the air inlet openings by configuring them as nozzles with specific convergence angles and dimensions. This parameter optimization allows efficient pressure generation from the available airflow, achieving high pressure output from a compact impeller without the noise penalties associated with larger diameter impellers operating at lower pressures
3Ease of operation
If a separate drive unit is added to the fan, then the fan can be driven independently, but the device complexity increases and reliability decreases
Solution Approach 1:
The fan drive function is merged with the rotor shaft, which already rotates at the required speed for fan operation. The rotor shaft directly drives the impeller without requiring a separate motor or drive mechanism, thereby eliminating additional components while maintaining effective fan operation synchronized with the rotor speed
Solution Approach 2:
The rotor shaft serves multiple functions: it transmits mechanical power from the motor, supports the rotor assembly, and simultaneously acts as the drive shaft for the cooling fan. This multi-functionality eliminates the need for a dedicated fan drive unit, reducing device complexity while ensuring the fan operates at the appropriate speed for effective cooling
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 configuration reduces noise emissions, enhances cooling efficiency, and increases fan reliability by maintaining small impeller diameters for high-speed operations while minimizing axial forces and noise transmission, achieving better efficiency and noise reduction.
Implementation Method 1
at least one of the two air inlet openings is designed, at least in regions, in the manner of a nozzle
Implementation Method 2
a heat exchanger which can be charged with cooling air and which is arranged on the housing and connected to the cooling device
Implementation Method 3
The cooling fluid and the cooling air are materially separated in the heat exchanger
Implementation Method 4
a cooling device for dissipating heat out of the housing
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to an electric machine (40) comprising: a housing (12), a stator, a rotor which is rotatably mounted in a receiving area of the stator, a cooling device for discharging heat out of the housing (12), a heat exchanger (14) which can be supplied with cooling air and which is arranged on the housing (12) and is coupled to the cooling device, a cooling air channel (16), and a ventilator (48) for introducing the cooling air into the cooling air channel (16). The ventilator (48) has a ventilator wheel (42) which is mounted in a ventilator housing (50) in a rotatably drivable manner, and the ventilator housing (50) has two opposing air inlet openings (44, 46), between which the ventilator wheel (42) is arranged, and at least one air outlet opening (52) arranged in a radial direction of the ventilator wheel (42). The aim of the invention is to improve the electric machine with respect to noise emission. According to the invention, at least some regions of one of the two air inlet openings (44, 46) have a nozzle-type design (54, 56).