Liquid level detector

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Solution Overview

Problem

Existing liquid level detection systems in air conditioning and pumping systems are prone to orientation-dependent failures and inefficiencies, leading to pump damage, noise, and reduced lifespan due to the reliance on float switches that require precise installation and can malfunction when pumping air.

Innovation Solution

A capacitive liquid level detector system with mutually spaced capacitive sensor elements outside the liquid chamber, utilizing a thin barrier member and an electronic controller to generate control signals for the pump, allowing for accurate liquid level detection and pump control regardless of the sensor's orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a float switch is used for liquid level detection, then the pump can be controlled to turn on and off based on liquid level, but the system becomes orientation-dependent and the float may get stuck, leading to pump damage and reduced reliability

Engineering Contradiction:

Improvepump operation reliabilityVSAvoidinstallation orientation requirement

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical float switch system with a capacitive sensor system that uses electrical fields to detect liquid levels. The capacitive sensor elements are positioned outside the liquid chamber separated by a barrier member, eliminating mechanical moving parts that can get stuck. This substitution removes the orientation dependency while maintaining reliable pump control based on liquid level detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a barrier member as an intermediary between the capacitive sensor elements and the liquid. This barrier member allows the sensor elements to be positioned outside the liquid chamber while still detecting liquid levels through capacitive coupling. The intermediary enables the sensor to function reliably without direct contact with the liquid, eliminating the need for precise orientation during installation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the pump runs continuously to ensure water is always available, then the pump may pump air when the reservoir is empty, causing pump damage and excessive noise

Engineering Contradiction:

Improvepump lifespanVSAvoidwater transport efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements a feedback control system where capacitive sensors continuously monitor the liquid level in the chamber and provide real-time information to the controller. The controller adjusts pump operation based on this feedback, turning the pump on when liquid is detected and turning it off when the chamber is empty. This feedback mechanism prevents the pump from running dry and pumping air, eliminating pump damage and excessive noise while maintaining efficient water transport.

Inventive Principle:

Principle #23Feedback

3Extent of automation

If a filling chamber with float switch is used, then the pump can be controlled, but the float switch requires precise mounting angle and additional components like air inlet and guide rail

Engineering Contradiction:

Improveautomatic pump controlVSAvoidnumber of components and installation requirements

Core Design Contradiction:

Extent of automationVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical float switch system with a simpler capacitive sensor system. The capacitive sensors can be mounted on the outer surface of the chamber wall without requiring precise orientation or additional mechanical components like guide rails. This substitution maintains automatic pump control while significantly reducing device complexity and easing installation requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 capacitive liquid level detector system ensures reliable and orientation-independent detection of liquid levels, preventing pump damage and noise, while maintaining efficient operation by controlling the pump speed and preventing air pumping, thus enhancing system reliability and longevity.

Implementation Method 1

a first capacitive sensor comprising mutually spaced capacitive sensor elements forming a capacitance which is sensitive to permittivity within a region of the chamber proximate the first capacitive sensor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

forming a capacitance which is sensitive to permittivity within a region of the chamber proximate the first capacitive sensor

Methodology Applied

Scientific EffectPermittivity: Dielectric Permittivity

Data Source

PatentUS10760938B2Liquid level detector

Publication Date: 2020.09.01 ASPEN PUMPS LIMITED

AI summary

A liquid level detector for use in a pump control system comprises a chamber 20 for liquid, a liquid inlet 6 to the chamber 20, a liquid outlet 7 from the chamber and connectable to a pump, and a capacitive sensor comprising mutually spaced capacitive sensor elements (21, 22; 22, 23) forming a capacitance which is sensitive to permittivity within a region of the chamber proximate the capacitive sensor. The chamber is defined at least partially by a barrier member 25 and the capacitive sensor elements are provided on the barrier member outside the chamber.