Photoelectric Smoke Detector Steam Interference Prevention
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Solution Overview
Problem
Conventional photoelectric smoke detectors can issue erroneous alarms due to steam entering the smoke detecting unit, and their design interferes with smoke flow, degrading smoke inlet characteristics.
Innovation Solution
The smoke detector design separates the installation section with light emitting and receiving elements from the smoke inlet section, with the smoke inlet section positioned below and communicating through an opening, featuring an inclined partition wall to guide smoke into the installation section while preventing steam from entering, and a light shielding member positioned to avoid obstructing smoke flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light shielding member is arranged to extend from the bottom surface to the top surface of the smoke inlet section, then the light receiving element is protected from direct infrared rays, but the smoke inlet characteristics are degraded due to interruption of smoke flow
Solution Approach 1:
The light shielding member is divided into two separate parts: a first light shielding member extending from the bottom surface to a first height, and a second light shielding member extending from the bottom surface to a second height (lower than the first height). This segmentation allows smoke to flow between the two members while still providing light shielding protection, thus resolving the contradiction between preventing erroneous alarms and maintaining smoke inlet characteristics.
2Device complexity
If the smoke detecting unit has a unified structure with light emitting and receiving elements within the smoke inlet section, then the device is simpler, but erroneous alarms occur when steam flows into the unit
Solution Approach 1:
The smoke detecting unit is divided into a smoke inlet section and a light emitting/receiving section. The light emitting element and light receiving element are positioned in the light emitting/receiving section, separated from the smoke inlet section. This spatial segmentation prevents steam entering the smoke inlet section from causing erroneous alarms while maintaining detection functionality.
Solution Approach 2:
The light emitting element and light receiving element are extracted from the smoke inlet section and placed in a separate light emitting/receiving section. This extraction removes the sensitive optical components from the path of incoming steam, eliminating the cause of erroneous alarms while preserving the smoke detection capability.
3Measurement precision
If the light emitting element and light receiving element are positioned close to the smoke inlet, then smoke detection sensitivity is improved, but steam enters the detection region causing erroneous alarms
Solution Approach 1:
The detector is segmented into a smoke inlet section where steam can enter freely, and a protected light emitting/receiving section where optical detection occurs. The partition wall with openings allows smoke to pass through while the separated positioning of optical elements prevents steam from reaching the detection region, thus maintaining sensitivity without steam interference.
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 design effectively prevents erroneous alarms from steam and enhances fire detection accuracy by ensuring smoke flows into the detection region while allowing steam to pass through, improving smoke inlet characteristics and detection performance.
Implementation Method 1
a light receiving element for receiving the light which is emitted from the light emitting element and is scattered by smoke particles within the smoke detecting unit
Data Source
AI summary
A photoelectric smoke detector is capable of preventing an erroneous alarm from being issued even when steam flows into a smoke detecting unit. The smoke detecting unit includes: an installation section; and a smoke inlet section. The installation section includes: a light emitting element for emitting light to an inside of the installation section; and a light receiving element for receiving the light emitted from the light emitting element. The smoke inlet section includes: a plurality of wall members for preventing external light from entering the smoke inlet section; and a smoke inlet formed between the plurality of wall members. The installation section and the smoke inlet section are arranged so as to overlap each other, with the smoke inlet section being positioned on a lower side of the installation section, and are communicated with each other through an opening.