Liquid Level Transducer With Isolated Sensors And Snap-Fit Assembly
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Solution Overview
Problem
Reed switch-type liquid level transducers suffer from hysteresis effects, premature switching, and corrosion due to exposure to the measured liquid, leading to inaccurate readings and short device lifespan, and are difficult to assemble due to numerous components.
Innovation Solution
A liquid level transducer design featuring a housing isolated from the liquid, with a snap-fit mounting system and a float rod connected to a pivotally moving actuator that changes the electrical state of sensor elements, preventing liquid exposure and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reed switches are exposed to the liquid being measured, then the transducer can directly detect liquid level, but the reed switches suffer from corrosion and premature failure
Solution Approach 1:
The patent introduces a magnetic coupling mechanism as an intermediary between the float (actuator) and the reed switches (sensor elements). The float contains a magnet that magnetically actuates the reed switches through the housing wall without direct liquid contact. This intermediary magnetic field transmission allows the sensor elements to remain isolated from the corrosive liquid environment while still detecting liquid level changes accurately.
2Measurement precision
If reed switches are aligned linearly to detect liquid level, then the transducer can measure multiple levels, but each reed switch opens and closes multiple times causing hysteresis and improper indication
Solution Approach 1:
The patent transitions from a linear arrangement of reed switches to a curved or arc-shaped arrangement. The float rod pivots in an arcuate path, and the reed switches are positioned along this curved trajectory. This dimensional change from linear to curved geometry ensures that each reed switch is actuated only once during the float's movement, eliminating the multiple open/close cycles and hysteresis effects associated with linear arrangements.
3Ease of manufacture
If a mounting head and elongate sensor probe are used, then the transducer can be constructed with modular components, but assembly becomes difficult and time-consuming
Solution Approach 1:
The patent integrates the sensor elements (reed switches) directly into the housing structure, eliminating the need for a separate mounting head and elongate sensor probe assembly. The housing serves multiple functions: it encloses the sensor elements, provides structural support, and acts as the mounting interface. This merging of functions reduces the number of discrete components and simplifies assembly while maintaining modular construction benefits.
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
The solution provides reliable, long-lasting liquid level measurements by isolating sensor components from corrosive liquids and reducing assembly complexity through a snap-fit connection, enhancing measurement accuracy and device durability.
Implementation Method 1
a float that moves in response to a change in liquid level
Implementation Method 2
The reed switches are normally responsive to the presence and absence of a magnetic field for opening and/or closing the switch
Data Source
AI summary
A transducer for determining the level of liquid within a container includes a mounting head adapted for connection to the container and a sensor assembly adapted to extend into the container. A housing of the sensor assembly has a hollow interior that is isolated from liquid within the container. A plurality of sensor elements are located within the interior. A float rod is pivotally connected to the housing and a float is connected to a distal end of the float rod. An actuator located outside the housing is operatively associated with the float rod for pivotal movement therewith. The actuator is operative to change an electrical state of at least one of the sensor elements to thereby indicate a level condition of the liquid within the container. A snap-fit assembly of the mounting head and sensor assembly is also disclosed.