Engine Noise Detection Using Ultrasonic Reference Sound
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Solution Overview
Problem
Existing knocking level evaluation systems for internal combustion engines rely on synthesizing sound pressure data with crank angle signals, making it difficult to estimate noise timing without direct use of crank angle signals.
Innovation Solution
An engine apparatus generates a specific sound with a higher frequency than the engine's operation sound in synchronization with the top dead center of a specific cylinder, allowing noise timing estimation based on sound deviations without using crank angle signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sound pressure data is synthesized using crank angle signals to evaluate knocking levels, then measurement precision is improved, but device complexity increases due to the need for angle detectors and signal synthesis systems
Solution Approach 1:
The patent extracts only the essential timing information needed for noise detection by using a simple reference sound generated at known top dead center timing, rather than synthesizing complete sound pressure data with crank angle signals. This removes the complex angle detector and signal synthesis components while retaining the ability to estimate noise timing accurately by comparing the reference sound timing with actual noise timing.
Solution Approach 2:
The patent introduces a reference sound generator as an intermediary device that produces a sound at a known timing (top dead center) to serve as a temporal reference. This intermediary allows the system to determine noise timing through simple temporal comparison rather than requiring complex crank angle signal synthesis and processing.
2Loss of information
If audible frequency sounds are used for engine operation, then user awareness of engine status is improved, but user comfort deteriorates due to uncomfortable or annoying sounds
Solution Approach 1:
The patent applies different frequency characteristics to different functional sounds: the reference sound used for timing estimation is generated at ultrasonic frequencies (above human audible range) to avoid user discomfort, while actual engine operation sounds remain in the audible range for user awareness. This local differentiation of sound quality allows the system to maintain engine status information transmission while eliminating uncomfortable reference sounds from the audible spectrum.
Solution Approach 2:
The patent changes the frequency parameter of the reference sound to be above the human audible frequency range (ultrasonic frequencies), thereby transforming it from a potentially uncomfortable audible sound into an inaudible reference signal that does not affect user comfort while still serving its timing reference function.
3Measurement precision
If crank angle sensors and angle signals are used for noise timing estimation, then measurement precision is improved, but ease of operation deteriorates due to the need for direct crank angle signal access
Solution Approach 1:
The patent makes the reference sound generator self-sufficient by generating its own timing reference internally synchronized with top dead center events, eliminating the need for the noise detection system to access or process crank angle signals from external sensors. The reference sound generator essentially creates its own timing reference, making the overall system easier to operate while maintaining precision.
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
Enables accurate noise timing estimation in internal combustion engines without relying on crank angle signals, reducing user discomfort and improving noise detection precision.
Implementation Method 1
a specific sound generator configured to generate a specific sound having a higher frequency than an operation sound of the engine in synchronization with timing of a top dead center of a specific cylinder of the engine
Data Source
AI summary
A specific sound having a higher frequency than an operation sound of an engine is generated in synchronization with timing of a top dead center of a specific cylinder of the engine. Thus, timing of a noise of the engine is estimated by using, for example, a deviation in time between timing of generation of a specific sound and timing at which a noise occurs in the engine, based on a sound collected from around the engine without directly using a signal of a crank angle of the engine.