Optical Switch System for Flow Prover Calibration
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Solution Overview
Problem
Conventional small volume provers for calibrating liquid flow meters face challenges in precise alignment and replacement of optical sensors, leading to potential misalignment and costly recalibration due to the integral nature of the position of the gate or slot, which can shift over time due to external factors like thermal cycling or vibration.
Innovation Solution
A switch bar with precisely mounted light emitter and detector modules, where a small aperture defines the trigger point, ensuring positional accuracy by maintaining a fixed position for the light beam, allowing for accurate detection of the piston's position without requiring recalibration, even when modules are replaced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors are precisely aligned and rigidly mounted to detect piston position, then measurement precision is improved, but device complexity and manufacturing cost increase due to precise placement requirements
Solution Approach 1:
The patent introduces a mechanical intermediary system consisting of a cam mechanism and follower that converts the linear motion of the piston into rotational motion of a dial indicator. This mechanical intermediary eliminates the need for direct optical sensing, thereby reducing alignment complexity while maintaining measurement precision through mechanical transmission ratios and geometric relationships.
Solution Approach 2:
The patent replaces the optical sensing system with a purely mechanical measurement system using a cam-follower mechanism and dial indicator. This substitution eliminates optical alignment requirements, sensor fragility, and associated complexity while providing robust, maintenance-free operation through proven mechanical principles.
2Measurement precision
If optical sensors are used to detect piston position, then measurement capability is improved, but reliability decreases due to sensor fragility and potential destruction from misalignment
Solution Approach 1:
The patent replaces fragile optical sensors with a robust mechanical cam-follower system where the follower rides on the cam surface without contact stress that could cause destruction. The mechanical system is inherently more reliable as it tolerates misalignment and physical contact without failure, eliminating the risk of sensor destruction from flag collision.
Solution Approach 2:
The cam mechanism is designed with inherent clearance and tolerance that accommodates manufacturing variations and thermal expansion before any potential contact or misalignment issues arise. The follower maintains consistent contact with the cam surface through pre-loaded spring mechanisms that compensate for wear and dimensional changes, ensuring long-term reliability.
3Measurement precision
If switch position is fixed integral to each optical sensor, then position reference is established, but ease of repair deteriorates as any movement requires recalibration
Solution Approach 1:
The patent replaces optical sensors with a mechanical dial indicator system mounted on a rigid bracket. The dial indicator can be easily removed and replaced without affecting the cam mechanism or requiring recalibration, as the mechanical reference is established by the cam geometry itself rather than by sensor position. This significantly improves ease of repair and maintenance.
Solution Approach 2:
The measurement system is segmented into independent components: the cam mechanism, the follower assembly, and the dial indicator. This segmentation allows the dial indicator to be replaced independently without affecting the cam geometry or requiring system recalibration, thereby improving maintainability while preserving measurement accuracy.
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 solution provides precise and accurate detection of the piston's position within the prover, reducing the need for recalibration and minimizing the risk of misalignment, thus enhancing the accuracy and efficiency of flow meter calibration without increasing complexity or cost.
Implementation Method 1
directing a beam of light from an emitter through a very small aperture at a fixed location to a detector
Data Source
AI summary
Apparatus for flow prover precisely measures the volume and the flow rate of a fluid through a cylinder. The prover includes a piston within a cylinder supporting a shaft extending longitudinally through the cylinder, which cylinder receives and discharges the fluid by translation of the piston from the fluid receiving end to the fluid discharging end. Motive means draws the shaft and piston toward the fluid receiving end of the cylinder. Travel of the piston in the direction from the fluid receiving end to the fluid discharging end of the cylinder is sensed at discrete locations to provide an indication of the volume of fluid therebetween and the related flow rate. Each of a plurality of emitter/detector modules provides piston position sensing signals reflective of the volume and rate of fluid flowing through the cylinder. A switch bar rigidly and permanently fixes the position of the emitter/detector modules with respect to the piston and with respect to one another. An immovable gate or aperture regulates the cross-section of the light beam striking the detector and ensures that the measured volume is repeatable and cannot be altered due to external factors such as in-field use, service, maintenance on components or the like.