Dual Cooling Fan Heat Exchanger Control for Lower NVH
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Solution Overview
Problem
Existing heat exchanger systems in vehicles often experience objectionable acoustic properties due to the operation of multiple cooling fan modules, which can lead to noise, vibrations, and harsh noise vibrations (NVH) tones, especially when the fan modules operate at high speeds or have similar rotational speeds.
Innovation Solution
A heat exchanger system comprising two cooling fan modules with a controller that adjusts their rotational speeds to maintain a speed differential, thereby mitigating objectionable acoustic properties. The system receives demanded heat rejection rates for each heat exchanger and adjusts the fan speeds accordingly to ensure acoustic properties remain below a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple cooling fan modules operate at high speeds to meet heat rejection requirements, then heat rejection rate is improved, but acoustic properties deteriorate due to noise and vibrations
Solution Approach 1:
The controller dynamically adjusts the rotational speeds of multiple cooling fan modules to maintain a speed differential between them. By changing the operational parameters (rotational speeds) of the fans rather than operating them at fixed high speeds, the system meets heat rejection requirements while reducing acoustic harmonics and vibrations that occur when fans rotate at identical speeds.
Solution Approach 2:
The system implements periodic modulation of fan speeds through differential rotation. By introducing a speed differential that creates non-synchronized periodic motion between multiple fans, the system disrupts the formation of consistent acoustic harmonics and NVH tones while maintaining adequate cooling performance.
2Device complexity
If cooling fan modules operate at similar rotational speeds to simplify control, then device complexity is reduced, but acoustic properties worsen due to synchronized vibrations
Solution Approach 1:
The controller maintains relatively simple control logic while dynamically adjusting fan speed parameters. By implementing a speed differential strategy where one fan operates at a base speed and another operates at a differentiated speed, the system achieves acoustic mitigation without requiring complex multi-variable control algorithms.
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 system effectively reduces objectionable acoustic properties by maintaining a speed differential between the two cooling fan modules, ensuring that the heat exchanger system operates with improved noise and vibration management while meeting thermal management requirements.
Implementation Method 1
The first cooling fan module may be provided with a first fan and a first motor, the first motor may be configured to drive the first fan to cool the first heat exchanger
Implementation Method 2
The first heat exchanger may be configured to cool a first functional component of the vehicle and the second heat exchanger may be configured to cool a second functional component of the vehicle
Data Source
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AI summary
A heat exchanger system including a controller configured to direct a first power signal to a first cooling fan module to operate a first motor at a first rotational speed to provide a first flow rate to satisfy the first demanded heat rejection rate, direct a second power signal to the second cooling fan module to operate the second motor at a second rotational speed to provide a second flow rate to satisfy the second demanded heat rejection rate while maintaining a rotational speed differential between the first rotational speed and the second rotational speed, such that an acoustic property of at least one of the first heat exchanger assembly and the second heat exchanger assembly is below a predetermined acoustic property threshold.