Fiber Optic Flow Sensor Using Bend-Induced Light Loss for BMS
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Solution Overview
Problem
Building management systems (BMS) face challenges in obtaining reliable flow measurements due to the high cost and labor intensity of installing flow sensors, which are often required for optimal control of building equipment, especially in areas where flow sensors are not already present.
Innovation Solution
A fiber optic flow sensor system that uses a fiber optic cable with a light emitter and optical power meter to calculate fluid flow rate by measuring power loss and bend radius, allowing for non-invasive installation and cost-effective flow measurement, with the ability to transmit data to HVAC components for control purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional flow sensors are installed in pipes to obtain flow measurements, then measurement precision is improved, but device complexity and installation cost increase
Solution Approach 1:
The patent replaces traditional mechanical flow sensors with an optical measurement system. A fiber optic cable is inserted through a small access hole in the pipe, and light emission/ detection mechanisms measure flow-induced cable deflection optically, eliminating the need for complex mechanical sensor installation in the pipe stream.
Solution Approach 2:
The fiber optic cable acts as an intermediary element that translates mechanical flow effects (deflection due to flow-induced vibration or pressure) into optical signals. The cable is inserted through a minimal access hole and its deflection is measured optically, serving as a mediator between the fluid flow and the measurement system.
2Reliability
If flow sensors are installed in all desired locations for optimal BMS control, then reliability of flow knowledge is improved, but loss of time and labor for installation increases
Solution Approach 1:
The measurement system is segmented into modular components: a fiber optic cable that can be independently inserted through small access holes, and an external optical measurement device. This segmentation allows multiple sensors to be installed quickly at different locations without complex piping modifications at each site.
Solution Approach 2:
The installation process is simplified by replacing traditional mechanical sensor mounting with optical measurement through fiber optic cables inserted through minimal access holes, dramatically reducing installation time and labor while enabling deployment at multiple locations.
3Difficulty of detecting and measuring
If fiber optic cable is exposed to fluid flow to measure bend radius, then measurement capability is improved, but object-generated harmful factors increase due to light power loss
Solution Approach 1:
The patent uses optical detection methods to measure fiber optic cable deflection caused by flow-induced effects. By using light emission and detection through the fiber optic cable rather than electrical measurements, the system achieves sensitive flow detection while minimizing power loss and avoiding electromagnetic 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
Enables accurate and cost-effective measurement of fluid flow rates without the need for extensive sensor installation, improving the operational efficiency of building management systems by integrating with HVAC components for optimal control.
Implementation Method 1
The fiber optic cable is configured to allow light to enter a first end of the fiber optic cable, reflect off a second end of the fiber optic cable, and exit the fiber optic cable through the first end
Implementation Method 2
The optical power meter is configured to measure an output power of the light exiting the fiber optic cable at the first end after the light has reflected off the second end of the fiber optic cable and returned to the first end of the fiber optic cable
Data Source
AI summary
A fiber optic flow sensor includes a fiber optic cable, a light emitter, an optical power meter, and a processing circuit. The fiber optic cable allows light to enter a first end of the fiber optic cable, reflect off a second end of the fiber optic cable and exit the fiber optic cable through the first end. The fiber optic cable is at least partially exposed to fluid flow at the second end. The light emitter emits light at an input power into the first end of the fiber optic cable. The optical power meter measures an output power of the light exiting the fiber optic cable at the first end. The processing circuit calculates a flow rate of the flow of fluid based on the input power of light entering the fiber optic cable and the output power of light exiting the first end of the fiber optic cable.