IAQ Sensor Sampling Interval Adjustment for Battery Life Extension
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Solution Overview
Problem
Existing IAQ sensors in HVACR systems face challenges in extending battery life while maintaining reliable data sampling, particularly due to the high energy consumption of detectors like CO2 and VOC sensors.
Innovation Solution
The method involves determining an occupancy schedule based on historical IAQ levels, allowing the IAQ sensor to adjust its sampling interval accordingly. During unoccupied periods, the sensor detects IAQ levels at longer intervals, reducing overall detection numbers and conserving battery life without relying exclusively on a PIR module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IAQ detector continuously monitors IAQ levels at a short sampling interval, then the reliability of data is improved, but the battery life is reduced due to high energy consumption
Solution Approach 1:
The patent applies dynamics by making the sampling interval adjustable rather than fixed. The system dynamically changes the sampling interval based on detected IAQ conditions - using shorter intervals when IAQ deteriorates to maintain data reliability, and longer intervals when IAQ is stable to conserve battery life. This resolves the contradiction by adapting the monitoring frequency to actual environmental conditions.
Solution Approach 2:
The patent changes the parameter of sampling interval based on IAQ level thresholds. When IAQ levels exceed predetermined thresholds, the system switches to a shorter sampling interval to capture rapid changes. When IAQ remains within acceptable ranges, the system extends the sampling interval to reduce power consumption. This parameter adaptation directly addresses the trade-off between data reliability and battery life.
2Loss of energy
If the sampling interval is increased to extend battery life, then the energy consumption is reduced, but the reliability of data detection is compromised
Solution Approach 1:
The system uses feedback from IAQ level measurements to control the sampling interval. When IAQ levels indicate poor air quality or rapid changes, the system automatically reduces the sampling interval to ensure reliable detection. When IAQ conditions are stable and acceptable, the system increases the sampling interval to conserve energy. This feedback mechanism ensures that data reliability is maintained only when necessary, optimizing energy consumption.
Solution Approach 2:
The sampling interval is made dynamic rather than static, allowing the system to adapt to changing IAQ conditions. The controller adjusts the sampling frequency in real-time based on environmental feedback, using shorter intervals during critical periods and longer intervals during stable periods. This dynamic adjustment resolves the contradiction between energy conservation and detection reliability.
3Duration of action of moving object
If a PIR module is used to detect occupancy for adjusting sampling intervals, then the battery life can be extended, but the device complexity increases
Solution Approach 1:
The IAQ sensor system performs self-service by using its own IAQ measurements to determine occupancy status and adjust sampling intervals, eliminating the need for external PIR modules. The system infers occupancy from IAQ level patterns and uses this information to dynamically adjust monitoring frequency. This self-service approach extends battery life without adding external components, thereby avoiding increased device complexity.
Solution Approach 2:
The IAQ sensor serves multiple functions: it monitors air quality levels, infers occupancy status from IAQ patterns, and controls its own sampling frequency. This multi-functionality allows the system to extend battery life through occupancy-based sampling adjustments without requiring a separate PIR module, thus avoiding additional complexity while achieving the desired energy conservation.
Data Source
AI summary
A method extends battery life of a battery powered indoor air quality (IAQ) sensor that includes a IAQ detector, a radio, the battery, and a microcontroller with a memory and a processor. The method includes detecting IAQ at predetermined intervals to provide IAQ levels, and storing the IAQ levels and corresponding timing data in the memory. The method further includes determining an occupancy schedule based on IAQ level patterns and subdividing the occupancy schedule into a plurality of periods. The method further includes determining an occupancy status of each of the periods based on the IAQ levels. The method further includes operating the IAQ detector to sample at an active interval when the occupancy status is the occupied and at an inactive interval when the occupancy status is the unoccupied. The inactive interval is longer than the active interval. The IAQ detector can be, for example, a CO2 detector or a VOC detector.