Air-Cooled Resistor Layout to Reduce Flow Separation Noise
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Solution Overview
Problem
Air-cooled resistor arrangements in electric vehicles face challenges in efficiently dissipating electric power during regenerative braking, particularly when the battery's State of Charge is above a certain threshold, leading to overheating and noise issues due to separated air flow regions.
Innovation Solution
An air-cooled resistor arrangement with elongated resistor elements arranged equidistantly in columns and wave-shaped rows within a housing, promoting uniform air flow and reducing separated air flow regions, thereby enhancing heat transfer and operational efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If resistor elements are arranged in conventional configurations, then the structure is simple, but separated air flow regions are created causing pulsations and noise
Solution Approach 1:
The resistor elements are arranged in an asymmetric pattern where the spacing between adjacent elements varies along the flow direction. Specifically, the distance between elements in one row is different from the distance between elements in the next row, creating an irregular, non-repeating configuration that prevents the formation of coherent vortices and reduces pulsations and noise.
Solution Approach 2:
The patent transitions from a simple linear or grid arrangement to a three-dimensional spatial configuration where elements are offset in both horizontal and vertical directions. This multi-dimensional arrangement disrupts the flow separation patterns that occur in planar configurations, eliminating the harmful pulsations and noise while maintaining effective heat dissipation.
2Productivity
If resistor elements are closely arranged to increase power density, then the compactness is improved, but heat transfer efficiency decreases due to air flow separation
Solution Approach 1:
The patent applies different spacing configurations to different regions of the resistor array. Elements in certain zones are positioned with specific spacing optimized for that local flow condition, allowing the air flow to attach properly to each element surface. This localized optimization ensures efficient heat transfer across the entire array while maintaining high power density through close overall arrangement.
3Temperature
If air flow velocity is increased to improve cooling, then the cooling efficiency is improved, but pulsations and noise are induced
Solution Approach 1:
The patent converts the potentially harmful effect of high-velocity air flow into a beneficial one by using the increased velocity to enhance heat transfer while the asymmetric geometry prevents the formation of coherent structures that would cause pulsations. The design accepts high flow velocity as input and transforms it into effective cooling without the negative side effects through clever geometric arrangement.
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 the risk of overheating, noise, and increases the operational lifetime of the resistor elements by ensuring efficient cooling and uniform air distribution, effectively dissipating electric power during regenerative braking.
Implementation Method 1
an air cooled resistor arrangement... air flowing between the air inlet and the air outlet... heat transfer between the elongated resistor elements and the air
Implementation Method 2
increase of the heat transfer between the elongated resistor elements and the air flowing between the air inlet and the air outlet
Implementation Method 3
electric power generated during braking... dissipated by an air cooled resistor arrangement... electric power dissipation
Data Source
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AI summary
The present invention relates to an air cooled resistor arrangement (200), comprising a resistor housing (202) comprising an air inlet (204), an air outlet (206), a first side wall (216) extending from the air inlet to the air outlet, and a second side wall (218) extending from the air inlet to the air outlet on an opposite side to the first side wall, a plurality of elongated resistor elements (300) arranged in the resistor housing, each one of the elongated resistor elements extending from the first side wall to the second side wall, wherein the plurality of elongated resistor elements is arranged in columns along a direction between the air inlet and the air outlet, wherein each one of the plurality of elongated resistor elements is arranged equidistantly to all its neighboring elongated resistor elements.