Active Vibration Noise Control Apparatus for Vehicle Turning
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Solution Overview
Problem
Existing active vibration noise control systems are ineffective when the paths followed by the front and rear road wheels of a vehicle diverge, leading to increased overall vibration noise and abnormal sounds in the passenger compartment.
Innovation Solution
An active vibration noise control apparatus that includes a front road wheel vibration detecting unit, a vehicle speed detecting unit, a delay time calculating unit, a rear road wheel reference signal output unit, a canceling sound output unit, and a steered state detecting unit, which suppresses the output of the rear road wheel canceling sound when the paths followed by the front and rear road wheels differ, thereby preventing noise enhancement and abnormal sound production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a canceling sound is output based on estimated rear road wheel vibrations, then vibration noise from rear road wheels is reduced, but overall vibration noise increases and abnormal sounds are produced when front and rear road wheels follow different paths
Solution Approach 1:
The system dynamically adjusts the rear road wheel canceling sound output based on real-time detection of steered state. When the vehicle is in a straight traveling state, the canceling sound is output normally; when turning is detected, the output is suppressed. This dynamic adaptation resolves the contradiction by changing system behavior according to operating conditions.
Solution Approach 2:
The steered state detecting unit acts as an intermediary that monitors vehicle steering conditions and controls the canceling sound output unit. This intermediary detection mechanism enables the system to identify when front and rear road wheels follow different paths and adjust accordingly, preventing abnormal sound production while maintaining noise reduction effectiveness.
2Object-affected harmful factors
If the rear road wheel canceling sound is continuously output, then rear road wheel vibration noise is suppressed, but the system complexity increases due to path deviation issues
Solution Approach 1:
The canceling sound control is segmented into two distinct modes: front road wheel canceling sound (always active) and rear road wheel canceling sound (conditionally active). This segmentation simplifies the control logic by clearly defining when each type of canceling sound should be output, reducing overall system complexity while maintaining effectiveness.
3Object-affected harmful factors
If the canceling sound is adjusted based on steered state detection, then sound silencing capability is maintained during turns, but the device complexity increases
Solution Approach 1:
The steered state detecting unit serves multiple functions: it detects vehicle turning conditions, determines path deviation between front and rear road wheels, and controls the canceling sound output suppression. This multi-functionality reduces the need for separate detection systems, thereby limiting the increase in device complexity while achieving the desired noise control during turns.
Data Source
AI summary
An ANC apparatus using so-called adaptive control is provided with a cancellation sound output means which outputs front wheel cancellation sound that cancels front wheel vibration noise due to front wheel vibration at a position to be silenced on the basis of a front wheel reference signal, and outputs rear wheel cancellation sound that cancels rear wheel vibration noise due to predicted rear wheel vibration at the position to be silenced on the basis of a rear wheel reference signal, and a turning state detection means which detects a turning state of a vehicle. When a difference in travel trajectory between a front wheel and a rear wheel is detected on the basis of the turning state, the cancellation sound output means suppresses the output of the rear wheel cancellation sound.