Engine Sound Cancellation During Idle-Stop
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Solution Overview
Problem
Existing engine start-stop systems cause perceivable changes in engine sound during idle-stops, which can be objectionable to operators and degrade the driving experience, as background noise adjustments are insufficient to mask these changes.
Innovation Solution
Generating and playing modified engine sounds using a dashboard speaker to cancel inherent spin-down and spin-up sounds, synchronizing the phase of the recorded sound with the inherent engine sound, and phasing out the recorded sound as the engine reaches the target idling speed, thereby maintaining a continuous engine idling sound perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine is shut down and restarted to improve fuel efficiency and emissions quality, then fuel consumption is reduced and emissions are improved, but perceivable changes in engine sound occur during spin-down, rest, and spin-up
Solution Approach 1:
A speaker system acts as an intermediary device to play predetermined or customizable engine sounds during the idle-stop period. This mediator masks the perceivable changes in engine sound during spin-down, rest, and spin-up by providing a continuous audio backdrop that blends with the actual engine sounds, thereby resolving the contradiction between fuel efficiency improvements and maintaining acceptable sound perception.
Solution Approach 2:
The system creates and plays copied or simulated engine sound recordings during the idle-stop period. These recorded sounds replicate the characteristics of normal engine operation, allowing the operator to perceive a continuous engine sound even when the engine is actually shut off, thus masking the harmful sound changes while maintaining the fuel-saving idle-stop function.
2Object-affected harmful factors
If background noise volume is increased to mask engine sound changes, then some masking effect is achieved, but the variations in engine sound during spin-down and spin-up are not effectively masked
Solution Approach 1:
The system dynamically adjusts the volume and characteristics of the background sound based on the engine's operational state. During spin-down, the background sound volume is increased to mask the decreasing engine sound. During spin-up, the background sound is blended with the increasing engine sound to maintain seamless perception. This dynamic adaptation ensures reliable masking throughout the entire idle-stop cycle, overcoming the limitation of static volume adjustment.
Solution Approach 2:
The system implements periodic action by playing predetermined engine sound recordings at specific intervals and with specific timing relative to the engine cycle. The background sound is activated before engine shutdown, maintained during the idle-stop period, and adjusted during restart, creating a periodic audio pattern that reliably masks the harmful sound variations throughout each engine cycle.
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 approach effectively reduces perceivable changes in engine sound during start-stop operations, enhancing the operator's experience by maintaining a seamless engine idling sound perception throughout.
Implementation Method 1
generating, through an electronic speaker, an engine sound responsive to an automatic engine stop
Implementation Method 2
commencing at least partial active engine noise cancellation upon the spin-down and ending said cancellation upon reaching stabilized idle in a subsequent restart
Data Source
AI summary
Methods and systems are provided for adjusting an engine sound audible to the operator in a vehicle cabin during an engine idle-stop. In one example, responsive to an engine idle-stop, modified versions of a generated engine sound may be played via a dashboard speaker during each of the engine spin-down, engine rest, and engine spin-up. The modified versions of a generated engine sound may at least partially cancel inherent engine spin-up and engine spin-down sounds while maintaining an engine idling sound.