Vehicle Loudspeaker Tuning for EV Warning and Horn Output
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Solution Overview
Problem
Existing acoustic vehicle warning systems for electric vehicles fail to produce the required sound pressure levels for both warning and horn signals, as they are either overdesigned or insufficient to meet legal requirements, particularly in terms of bandwidth and amplitude.
Innovation Solution
A loudspeaker system designed to output sound signals in a specific frequency range with a ⅓ octave frequency band having an amplitude level at least 5 dB higher than the average, incorporating a sound library with horn sound signals synthesized to meet legal requirements, and utilizing resonance effects to enhance sound pressure levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If broadband loudspeakers are used for AVAS warning signals, then the bandwidth requirement is met, but the sound pressure levels required for horn signals cannot be reached
Solution Approach 1:
The frequency spectrum is divided into multiple bands, with different loudspeakers handling different frequency ranges. High-frequency loudspeakers handle AVAS warning signals while low-frequency loudspeakers handle horn signals, allowing each to operate at optimal power levels for its function
Solution Approach 2:
The system uses multiple loudspeakers that can each serve multiple functions - the same loudspeaker can output both AVAS warning signals and horn signals depending on the operational mode, eliminating the need for separate dedicated devices
2Power
If loudspeaker power is increased to meet horn sound pressure levels, then horn functionality is achieved, but the system becomes overdesigned and inefficient for AVAS warning signals
Solution Approach 1:
The audio output is segmented by frequency bands, with low-frequency loudspeakers dedicated to horn signals requiring high power and high-frequency loudspeakers handling AVAS signals that require lower power, optimizing overall system efficiency
Solution Approach 2:
The system dynamically adjusts operational parameters based on function - when horn mode is activated, power is directed to low-frequency loudspeakers; when AVAS mode is active, power is directed to high-frequency loudspeakers, preventing overdesign
3Device complexity
If a single loudspeaker handles both AVAS and horn functions, then device complexity is reduced, but it cannot simultaneously meet both bandwidth and amplitude requirements
Solution Approach 1:
The system segments loudspeaker functions by frequency range, with each loudspeaker group handling specific frequency bands appropriate to different signal types, enabling both AVAS and horn functionality with optimized performance
Solution Approach 2:
The system dynamically switches between different loudspeaker groups based on the required function - high-frequency loudspeakers are activated for AVAS warnings while low-frequency loudspeakers are activated for horn signals, providing versatile functionality
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 generates both warning and horn signals that meet legal requirements, ensuring pedestrians are aware of approaching electric vehicles while maintaining a compact and efficient implementation.
Implementation Method 1
utilizing resonance effects to enhance sound pressure levels
Implementation Method 2
Direct current from the vehicle battery, e.g. 12V battery, is fed into a coil. The hammer moves towards the disc or vice versa.
Data Source
AI summary
An audible vehicle warning system is arranged for generating a horn signal and includes a loudspeaker system having a loudspeaker arranged for outputting sound signals at least in a selected frequency range comprising at least frequencies from 400 to 2 kHz, a sound library including one or more sound signals intended as a horn signal when output by the loudspeaker. Each of the sound signals has a ⅓ octave frequency band, which is taken as a reference frequency band. The reference frequency band contains at least a predetermined part of the total power of the sound signal. An ⅓ octave frequency band averaged response of the loudspeaker system has in a ⅓ octave frequency band corresponding to the reference frequency band an amplitude level, which is at least a given amount of dB above the average amplitude level in the selected frequency range.