Disconnection Detection Device for Vehicle Antitheft Horns
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Solution Overview
Problem
Existing antitheft devices in vehicles face performance degradation due to the vulnerability of wire harnesses connecting the horn and relay, which can be cut by thieves, leading to invalidation of the alarm system, and previous solutions that add shielding or weight to protect the horn also increase cost and space requirements.
Innovation Solution
A disconnection detection device is integrated into the vehicle's relay box, featuring a constant current circuit and disconnection detection circuit that monitors the output voltage of the wire harnesses, allowing independent power supply to the horns even if the wire harnesses are cut, ensuring horn sound can be output as an alarm, and is designed to be easily attachable with similar terminal connections as the plug-in relay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a shield portion is provided between the outside of the vehicle and the horn to protect the horn, then the horn is protected from damage, but the weight and cost of the horn device are increased
Solution Approach 1:
The invention extracts the protection function from the horn device itself and relocates it to the relay box area. By monitoring wire harness disconnection at the relay box and providing alternative power supply paths, the protection mechanism is separated from the horn assembly, thereby protecting the horn without adding weight to it.
Solution Approach 2:
The relay box and its control circuit serve as an intermediary between the power supply and the horn. Instead of directly protecting the horn with physical shielding, the system uses the relay box to detect wire harness status and control power supply, providing indirect protection while avoiding additional weight on the horn device.
2Strength
If a shield portion is provided to protect the horn, then the horn is protected from damage, but the cost of the horn device is increased
Solution Approach 1:
The protection function is extracted from the horn device and implemented in the relay box area using existing components and wiring. This eliminates the need for additional protective materials and reduces manufacturing costs while maintaining protection effectiveness.
Solution Approach 2:
The system uses the existing relay box and its control circuits to provide protection functionality. By leveraging already-present components for disconnection detection and alternative power supply control, the invention avoids additional manufacturing costs while achieving horn protection.
3Illumination intensity
If gaps are provided between the horn and shield portion to prevent complete shielding of alarm sound, then alarm sound transmission is maintained, but the attachment space of the horn is increased
Solution Approach 1:
The invention removes the need for physical gaps by extracting the protection function from the horn assembly and implementing it in the relay box. This eliminates the space requirements associated with shield portions and gaps, allowing compact horn installation while maintaining alarm sound transmission.
4Reliability
If the wire harness connecting the relay and horn is cut by a thief, then the horn cannot receive drive power, but the antitheft device effectiveness is invalidated
Solution Approach 1:
The system performs preliminary detection of wire harness disconnection at the relay box before the horn is affected. By monitoring the wire harness status in advance and preparing alternative power supply paths through the relay control circuit, the system maintains antitheft effectiveness even if the wire harness is cut during theft attempts.
Solution Approach 2:
The invention provides beforehand cushioning by establishing alternative power supply paths through the relay box. When wire harness disconnection is detected, the relay control circuit can activate alternative routes to supply power to the horn, cushioning against the harmful effect of wire harness cutting and maintaining system reliability.
5Measurement precision
If constant current is supplied to the wire harnesses for disconnection detection, then disconnection can be detected, but power consumption increases
Solution Approach 1:
The system implements periodic disconnection detection by controlling the constant current supply in intermittent cycles rather than continuously. The relay control circuit activates the constant current source at regular intervals to monitor wire harness status, achieving accurate disconnection detection while significantly reducing overall power consumption compared to continuous monitoring.
Data Source
AI summary
A disconnection detection device is provided with a disconnection detection unit including a constant current circuit configured to supply a constant current for disconnection detection to at least two horns through wire harnesses, and a disconnection detection circuit configured to determine the presence or absence of disconnection of the wire harnesses by monitoring an output voltage of the constant current circuit and configured to supply drive power through the wire harnesses by turning on the contact circuit independently of the horn switch in a case where disconnection of the wire harnesses has been detected. The disconnection detection unit is disposed in the relay box along with the plug-in relay.