Flow Delivery System Drive Signal Modulation for Air-Water Detection
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Solution Overview
Problem
Existing flow delivery systems in beverage machines fail to reliably distinguish between air and water flows, leading to pump deterioration and user dissatisfaction due to the lack of feedback when the water supply runs dry, as the impeller can rotate due to air flow when dry, causing the system to interpret it as water flow.
Innovation Solution
A flow delivery system that includes a monitoring device and a controller to differentiate between liquid and gas flows by altering the pump drive signal, allowing for the determination of whether a detected flow is air or water, thereby preventing prolonged dry operation and providing user feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flow meter is fully dry and air flows through it, then the impeller can rotate easily due to low friction, but this causes the system to incorrectly interpret air flow as water flow
Solution Approach 1:
The system changes the drive signal parameters (reducing power from first to second drive signal) to observe how the impeller responds under different conditions. By monitoring the impeller's rotational behavior at reduced power, the system can distinguish between air and water flow since water's higher friction and viscosity will affect rotation differently than air.
Solution Approach 2:
The system uses feedback from the flow meter's impeller rotation signal to determine whether the flowing substance is air or water. The controller monitors the impeller's response to the drive signal and uses this feedback to make an accurate determination, preventing incorrect operation.
2Device complexity
If the system uses a flow meter to detect when water runs out, then it avoids the need for a water level sensor, but it cannot reliably distinguish between air and water flow
Solution Approach 1:
The system maintains the simple single-sensor configuration while adding the capability to distinguish flow types by changing the drive signal parameters and observing the impeller's rotational response. This allows accurate air/water differentiation without adding a water level sensor.
Solution Approach 2:
The flow meter's impeller itself serves dual purposes: it both measures flow rate and indicates flow type through its rotational characteristics. By analyzing how the impeller responds to drive signals under different fluid conditions, the system makes the existing component perform the additional function of flow type detection.
3Duration of action of stationary object
If the pump operates in dry condition for too long, then it deteriorates due to lack of lubrication and cooling, but the system lacks feedback to alert the user
Solution Approach 1:
The system provides feedback by continuously monitoring the flow meter's impeller rotation signal and comparing it against expected patterns for water flow. When the system detects air flow instead of water flow, it generates an alert to notify the user, enabling timely intervention to prevent pump damage.
Solution Approach 2:
The system takes preliminary action by detecting air flow conditions before significant pump damage occurs. By monitoring the impeller's rotational characteristics and identifying air flow patterns early, the system can alert the user and prevent prolonged dry operation that would lead to pump deterioration.
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 system effectively prevents pump deterioration and user dissatisfaction by accurately distinguishing between air and water flows, ensuring timely shutdown of the pump when the water supply is depleted, eliminating the need for a water level sensor and enhancing system reliability.
Implementation Method 1
A magnetic sensor arrangement is for example provided, comprising a magnet or set of magnets on the impeller and a magnetic sensor. This sensor arrangement is used to detect the impeller's revolutions.
Implementation Method 2
When the flow meter is fully dry, the air flow generated by the water pump can easily cause the impeller to rotate
Implementation Method 3
Flow meters used in the above types of appliance normally make use of the moving fluid stream to turn an impeller
Data Source
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AI summary
A flow delivery system is for delivering and monitoring a liquid flow, using a pump, and a monitoring device (e.g. a flow meter). A controller determines if the flow is a liquid flow or a gas flow by reducing a drive signal for the pump from a first drive signal to a second drive signal. This changes the characteristics of both the pump drive signal and the characteristics of the resulting flow. Based on the change in said characteristics, the flow is determined to be a liquid flow or a gas flow.