Milk level measurement device and related measurement method
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Solution Overview
Problem
Existing milk level measurement devices in coffee machines using hydrostatic pressure face instability in pressure values during suction, leading to measurement errors and incremental measurement based on liquid consumption, which are not optimally addressed by prior art.
Innovation Solution
A device with a valve between the suction pump and pressure sensor prevents backflow, allowing stable hydrostatic pressure measurement, and a control unit calculates liquid quantity based on measured levels and container size, using a control unit to manage the pump and valve operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hydrostatic pressure measurement is used during suction, then liquid level can be determined, but pressure values become unstable causing measurement errors
Solution Approach 1:
The system performs measurement during a pre-suction phase before actual liquid consumption begins. The pump activates briefly to establish hydrostatic pressure in the tube, then stops to allow stable pressure measurement. This preliminary action separates the measurement process from the suction process, ensuring stable readings without interfering with liquid consumption.
Solution Approach 2:
The system uses periodic activation of the pump to create cycles of suction and pause. During each pause cycle, the pump stops and the valve closes, allowing the pressure sensor to capture stable hydrostatic pressure values. This periodic rhythm enables multiple measurement opportunities while maintaining overall liquid consumption functionality.
2Measurement precision
If incremental measurement based on liquid consumption is used, then level can be tracked, but measurement is not optimal and accumulates errors
Solution Approach 1:
The system replaces incremental mechanical tracking (based on pump consumption cycles) with direct hydrostatic pressure sensing. Instead of calculating remaining liquid based on how much has been pumped, the sensor directly measures the current liquid level through pressure, providing absolute positioning without accumulation of measurement errors over time.
3Productivity
If pump operates continuously for suction, then liquid is consumed efficiently, but pressure sensor cannot measure stable hydrostatic pressure
Solution Approach 1:
The system segments the pump operation into distinct phases: active suction phase for liquid consumption and pause phase for measurement. A control unit manages this segmentation, activating the pump for consumption then deactivating it briefly for pressure measurement. This temporal segmentation allows both high productivity during suction and stable measurements during pauses.
Solution Approach 2:
The system introduces a control unit as an intermediary between the pump and pressure sensor. This controller coordinates their operations, ensuring the pump stops at appropriate moments for measurement while resuming for consumption. The intermediary manages the trade-off between productivity and measurement quality without direct conflict between components.
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 and stable milk level measurements, enabling accurate calculation of remaining liquid and preventing insufficient milk deliveries by blocking products requiring excessive amounts, with flexible placement and adaptation to various container shapes.
Implementation Method 1
determining a level of a liquid in a tank by means of a pressure sensor (15) arranged to measure a hydrostatic pressure in a tube (14)
Implementation Method 2
a valve (18), interposed between a suction pump (19) and a pressure sensor (15), and arranged to impede back flow of the liquid into the container
Data Source
AI summary
A device arranged for measuring a level of a liquid in a container. The device has a sensor, arranged to sense a pressure of a liquid in a tube, a pump arranged to pump the liquid from the container through the tube, and a valve located along the tube between the sensor and the pump and arranged to impede back flow of the liquid into the container when the pump stops pumping the liquid. The device is arranged to measure the level of the liquid into the container on the basis of the hydrostatic pressure measured by the sensor after each stop of the pump. Also disclosed is a method for measuring a level of a liquid in a container by a pressure sensor.