Fluid Flow Meter with Normalized Output Pulses
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Solution Overview
Problem
Conventional fluid flow meters face accuracy and measurement uncertainty issues, particularly at low flow rates and near maximum flow conditions, due to manufacturing tolerances and non-integer pulse rates, which affect their ability to provide precise volume measurements.
Innovation Solution
A fluid flow meter design featuring intermeshing gears with a controller that generates normalized output pulses based on detection signals from a flow sensor, allowing for precise measurement by incrementing a volume counter and transitioning pulse generation states based on predefined reference volumes, thereby compensating for variability in factory calibration and manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional factory calibration is used to correlate volume to rotational count, then the flow meter can provide basic measurement functionality, but measurement accuracy deteriorates outside the calibrated flow range and at low flow rates
Solution Approach 1:
The system dynamically adjusts the pulse generation rate based on actual flow conditions. The controller monitors the actual rotational speed of the gears and adjusts the pulse output frequency accordingly, allowing accurate measurement across varying flow rates rather than relying on a fixed factory calibration
Solution Approach 2:
The system changes the relationship between rotational count and pulse output based on operating conditions. By using a variable pulse rate that adapts to flow rate changes, the system maintains measurement accuracy across the full operating range rather than being limited to a single calibrated point
2Ease of manufacture
If manufacturing tolerances are accepted in gear fabrication, then production cost and complexity are reduced, but measurement accuracy and reliability deteriorate due to non-integer pulse rates
Solution Approach 1:
The system incorporates feedback from flow sensors that monitor actual gear rotation and fluid flow conditions. This feedback allows the controller to compensate for manufacturing variations in real-time, maintaining accurate measurements despite tolerances in gear fabrication
Solution Approach 2:
The system self-adjusts to compensate for manufacturing tolerances through continuous monitoring and dynamic pulse rate adjustment. The controller automatically corrects for variations in gear dimensions and meshing characteristics without requiring precision manufacturing
3Device complexity
If pulse generation is based directly on gear rotation without normalization, then device complexity is minimized, but measurement reliability deteriorates at low flow rates and near maximum flow conditions
Solution Approach 1:
The system introduces a controller as an intermediary between the mechanical gear rotation and the electrical pulse output. This controller normalizes the pulse generation process by monitoring actual flow conditions and adjusting pulse timing accordingly, ensuring reliable measurements across all flow rates
Solution Approach 2:
The system performs preliminary normalization of the pulse signal based on expected flow conditions before actual measurement occurs. By pre-establishing the relationship between rotational speed and pulse rate, the system ensures accurate measurements from the start of operation
Data Source
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Figure 3A~3B
Figure 4A~4D
AI summary
A fluid flow meter is described, that includes intermeshing gears that may rotate synchronously. The fluid flow meter may produce a pulsed output that can be normalized to suitable values according to a method of normalizing input pulses generated in response to the rotation of gears. A volume counter can be incremented by an amount equal to a volume per input pulse each time an input pulse is generated. When the volume counter exceeds a first reference volume, a normalized output pulse can be generated until the volume counter exceeds a second reference volume.