Chamberless Duct Smoke Detector With Self-Cleaning Airflow Alignment
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Solution Overview
Problem
Existing duct detectors for HVAC systems face issues with false alarms due to dust accumulation and require frequent maintenance, often necessitating replacement, and have varying sampling pipe lengths and hole spacings based on duct size.
Innovation Solution
A detector assembly with an optical detector system mounted to the exterior or embedded within a tube body, featuring a rotatable inner sampling support with a cleaning mechanism and actuation mechanism, allowing for efficient self-cleaning and reduced false alarms by positioning detectors to maximize airflow velocity for dust removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If detectors are mounted in a chamber outside the duct with sampling pipes, then detection capability is provided, but dust accumulates within the chamber causing false alarms and frequent maintenance
Solution Approach 1:
The patent removes the chamber that houses the detectors from the external mounting structure and places it directly inside the duct. This extraction eliminates the enclosed space where dust could accumulate, allowing detectors to operate in a dust-free environment while maintaining their detection function through direct exposure to duct airflow.
Solution Approach 2:
The patent transitions from a three-dimensional enclosed chamber to a two-dimensional surface mounting approach. Detectors are mounted on the exterior surface of the duct rather than inside a chamber, eliminating the internal volume where dust accumulation occurs while maintaining detection capability through strategic positioning and airflow alignment.
2Reliability
If maintenance is performed frequently to remove dust accumulation, then false alarms are reduced, but time and operational disruption increase
Solution Approach 1:
The patent performs preliminary action by mounting detectors directly on the duct exterior where they are naturally protected from dust accumulation. This preventive design eliminates the need for frequent maintenance interventions, as the mounting structure itself prevents dust buildup rather than requiring periodic cleaning to remove it.
Solution Approach 2:
The detector mounting structure provides self-service by using the duct's own airflow to prevent dust accumulation on the detectors. The design leverages the existing HVAC system airflow to keep the detector surfaces clean, eliminating the need for external maintenance activities.
3Adaptability or versatility
If sampling pipes with varying lengths and hole spacings are used for different duct sizes, then detection coverage is optimized, but device complexity and installation difficulty increase
Solution Approach 1:
The patent creates a universal mounting structure that can be applied to ducts of various sizes without requiring custom sampling pipes. The simple exterior mounting design with strategically positioned detectors provides adequate detection coverage across different duct dimensions, eliminating the need for complex, size-specific sampling pipe configurations.
Solution Approach 2:
Instead of extending sampling pipes inward from the duct exterior to reach detection points, the patent inverts the approach by mounting detectors directly on the exterior surface. This reversal eliminates the need for complex internal sampling pipe structures while maintaining detection effectiveness through direct airflow interaction.
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 solution reduces false alarms and maintenance needs by effectively cleaning the detectors and maintaining accurate detection of hazardous conditions within the duct, regardless of duct size, through efficient airflow alignment and self-cleaning capabilities.
Implementation Method 1
The light source emits a light beam across a detection chamber... the light beam encounters objects, such as smoke particles... the light is scattered and/or absorbed
Implementation Method 2
positioning detectors to maximize airflow velocity for dust removal
Data Source
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AI summary
A detector assembly 30 for a duct 20 of a heating ventilation and air conditioning system includes an outer housing 32 having at least one through hole 42 formed therein, an inner sampling support 34 receivable within a hollow interior 40 of the outer housing 32, and at least one detector 36 mounted to the inner sampling support 34. The at least one detector 36 is axially aligned with the at least one through hole 42 when the inner sampling support 34 is installed within the hollow interior 40 of the outer housing 32. The at least one detector 36 is operable to sample air within the duct 20 to detect a hazardous condition.