Drive Train Speed Fluctuation Detection Near Resonance
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Solution Overview
Problem
Existing methods for detecting speed/torque fluctuations in drive devices, such as dual-mass flywheels, are not precise enough, leading to unfavorable operating behavior and potential damage due to resonance, necessitating an improved method for accurate detection and analysis.
Innovation Solution
A method involving repeated measurement of the output shaft speed, transformation into the frequency domain using FFT, identification of local speed minima and maxima, and determination of local oscillation patterns to create a database for comparison with predefined patterns, enabling precise detection and control of speed/torque fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods for detecting speed/torque fluctuations are used, then the detection process is simple, but the measurement precision is insufficient leading to unfavorable operating behavior
Solution Approach 1:
The patent replaces mechanical detection methods with signal processing methods. Specifically, it transforms speed signal data into the frequency domain using Fast Fourier Transform (FFT) and applies wavelet transform techniques to extract fluctuation characteristics. This substitution of mechanical measurement with computational signal processing enables precise detection of speed/torque fluctuations without requiring complex mechanical sensing equipment.
Solution Approach 2:
The patent performs preliminary signal processing steps before final analysis. It first transforms the speed signal into the frequency domain using FFT, then applies wavelet transform to the frequency domain data. This preliminary transformation prepares the data in a form that enables precise identification of fluctuation patterns, allowing the system to detect critical conditions before they lead to unfavorable operating behavior.
2Object-affected harmful factors
If dual-mass flywheels are used to reduce torque fluctuations, then speed fluctuations are reduced, but resonance can occur at natural frequencies causing unfavorable operating behavior
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring speed fluctuations, transforming the signals to the frequency domain, and comparing the spectral content against known natural frequencies of the dual-mass flywheel. When fluctuations near resonance frequencies are detected, the system can provide feedback to the control unit to adjust operating parameters or alert the driver, preventing unfavorable operating behavior while maintaining the vibration reduction benefits of the dual-mass flywheel.
Solution Approach 2:
The patent utilizes vibration analysis principles by transforming speed signals into the frequency domain using FFT and wavelet transform. This allows the system to identify characteristic vibration frequencies corresponding to the natural frequencies of the dual-mass flywheel. By monitoring these vibrational signatures, the system can detect when the flywheel is operating near resonance conditions and take appropriate measures to avoid unfavorable operating behavior.
3Ease of operation
If speed/torque fluctuations are not accurately detected, then the drive train operates without precise control, but critical speed situations and potential damage occur
Solution Approach 1:
The patent replaces complex mechanical monitoring systems with computational signal processing. By using FFT and wavelet transform to analyze speed signal data, the system can accurately detect critical speed situations and fluctuation patterns without requiring additional mechanical sensors or complex hardware. This substitution maintains ease of operation while providing precise detection capabilities to prevent drive train damage.
Solution Approach 2:
The patent introduces signal processing techniques as an intermediary between the raw speed signal and the control system. The FFT and wavelet transform act as intermediaries that extract meaningful fluctuation characteristics from the speed data, enabling the control unit to identify critical conditions without direct mechanical contact or complex sensing. This intermediary processing layer provides accurate detection while keeping the overall system relatively simple.
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 method allows for precise detection and analysis of speed/torque fluctuations, preventing critical speed situations and reducing stress on the drive train, thereby enhancing driving comfort and extending the lifespan of torsional vibration influencing devices.
Implementation Method 1
transformation into the frequency domain using FFT
Data Source
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AI summary
The application relates to a method for detecting rotational speed/torque fluctuations, in particular patterns of such fluctuations, of a drive device, in particular in a motor vehicle, said method comprising the following steps: detecting a critical rotational speed situation by comparing a measured actual rotational speed with specified characteristic rotational speeds; detecting a local rotational speed minimum and a local rotational speed maximum (local rotational speed variables); analyzing said local rotational speed variables by generating local rotational speed characteristic values, such as a local amplitude and a local frequency preferably; directly or indirectly determining the duration of a local vibration time period, wherein substantially constant local rotational speed characteristic values are present within said time period; and describing a local vibration pattern, said pattern exhibiting at least the local amplitude, local frequency, or the local vibration time period.