One-Time Activation Smoke Alarm Mechanical Interlock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional smoke alarms can be turned off after activation, which does not meet the UL 217 standard requiring a 10-year battery life without the ability to turn off the device once activated.
Innovation Solution
A one-time activation smoke alarm design that includes a sliding sheet mechanism connected to a backward-proofing mechanism, preventing the smoke alarm from being turned off once activated. The smoke alarm is powered on by engaging a protrusion platform with a recessed slot, ensuring the detection function remains active until the device reaches the end of its life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the smoke alarm allows the detection function to be turned off after activation, then the ease of operation is improved, but the reliability deteriorates because it cannot meet the UL 217 standard requiring continuous operation for 10 years
Solution Approach 1:
The slide switch is divided into two independent components: a movable slider and a fixed switch body. The slider can be moved to turn off the detection function, but the fixed switch body includes a blocking protrusion portion that prevents the slider from returning to the on position, ensuring one-time activation compliance while maintaining user control capability
Solution Approach 2:
The blocking protrusion portion acts as a disposable mechanical element that is used once during installation to prevent future reversal of the activation state. This simple mechanical feature ensures the alarm cannot be turned off after activation, meeting UL 217 requirements without complex electronic controls
2Reliability
If the smoke alarm is designed to prevent turning off after activation, then the reliability is improved by meeting UL 217 standard, but the ease of operation deteriorates because the user cannot disable the device
Solution Approach 1:
The blocking protrusion portion is pre-configured in the fixed switch body to prevent future reversal of the activation state. During installation, the slider is moved to the off position, and the blocking protrusion portion mechanically prevents it from returning to the on position, ensuring continuous operation without requiring user intervention later
3Ease of operation
If the smoke alarm body can be repeatedly mounted and dismounted from the wall-hanging base, then the ease of operation is improved, but the reliability deteriorates because the alarm could be accidentally reactivated after reaching end of life
Solution Approach 1:
The mounting mechanism is segmented into a mounting protrusion on the alarm body and a corresponding recess on the wall-hanging base. The blocking protrusion portion extends into the engaging recessed slot to prevent dismounting when the alarm has reached end of life, while still allowing normal mounting and dismounting operations during the alarm's service life
Solution Approach 2:
The blocking protrusion portion acts as an intermediary mechanical element that mediates between the mounting mechanism and the dismounting action. When the alarm reaches end of life, this protrusion physically blocks the dismounting process, preventing accidental reactivation while allowing normal operation during the service period
Data Source
AI summary
A one-time activation smoke alarm includes a smoke alarm body and a wall-hanging base. The smoke alarm body includes a case and a sliding sheet. An engaging recessed slot and a supporting protrusion platform are respectively formed on two sides of a bottom of the case. The sliding sheet is slidably disposed on the supporting protrusion platform, and a front end of the sliding sheet has a pressed protrusion portion that extends into the engaging recessed slot. An engaging protrusion platform is formed on the wall-hanging base, and at least one abutting protrusion portion protrudes outward from a periphery of the engaging protrusion platform. The engaging protrusion platform and the engaging recessed slot are capable of being engaged and fixed together such that the abutting protrusion portion abuts the pressed protrusion portion and the smoke alarm body activates a detection function.