Coffee Machine Flow Rate Calculation Without a Flow Meter
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Solution Overview
Problem
Existing methods for determining the flow rate in hot beverage machines, such as coffee machines, often require multiple temperature sensors and mechanical flow meters, which can be complex and inaccurate.
Innovation Solution
A method that determines the flow rate using a single temperature sensor by measuring the liquid temperature and the air space temperature of the machine, calculating the heat output, and using a material constant to derive the flow rate without mechanical flow meters, allowing for a simplified and accurate determination of both volume and mass flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple temperature sensors and mechanical flow meters are used to determine flow rate, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the temperature measurement function from the flow rate determination process. Instead of using multiple temperature sensors to directly measure flow, the invention uses a single temperature sensor to measure outlet temperature and combines this with power consumption data and material constants to calculate flow rate. This extraction of the temperature measurement function reduces the number of sensors needed while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces mechanical flow meters with a thermal-based calculation system. Instead of using mechanical components to directly measure and indicate flow rate, the invention substitutes a system that uses electrical power consumption data, temperature measurements, and material constants to calculate flow rate mathematically. This substitution eliminates mechanical flow meters while improving measurement precision.
2Measurement precision
If multiple temperature sensors are used to measure temperature difference upstream and downstream of the heater, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the inlet temperature measurement function and replaces it with an alternative approach. Instead of using a temperature sensor upstream of the heater, the invention uses the known relationship between heater power consumption and temperature rise to infer the temperature difference. This extraction reduces the number of temperature sensors from two to one while maintaining measurement accuracy.
Solution Approach 2:
The patent enables the heater to serve dual functions: heating the liquid and providing power consumption data that is used to calculate the temperature difference. By monitoring the electrical power consumed by the heater and combining it with the outlet temperature measurement and material constants, the system can determine the temperature difference without requiring a separate upstream temperature sensor. The heater essentially provides its own measurement data through its power consumption characteristics.
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 approach enhances the accuracy of flow rate determination by eliminating the need for multiple sensors and mechanical meters, reducing complexity and improving precision, while also accounting for transient processes and beverage-specific setpoints.
Implementation Method 1
a liquid heater arranged between the supply opening and the discharge opening... determining the heating output and calculating a quotient representing the flow from the heating output
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for determining the flow of liquids in a coffee machine (2), which has a supply opening (4) and a discharge opening (6) for the liquid and a liquid heater ( 8) and a temperature sensor (10) downstream of the liquid heater (10), the flow rate being determined by determining the heating power (Q) and calculating a quotient representing the flow rate from the heating power (Q) and the material constant specific to the liquid (c) multiplied temperature difference (ΔT) is determined without a flow meter. According to the invention, the temperature difference (ΔT) is determined from the measurement of the liquid temperature (Tmeas) and an ambient temperature (Troom) of the coffee machine (2). The invention also includes a coffee machine (2) with a flow rate determination device (12) with which the temperature difference (ΔT) can be determined from the liquid temperature (Tmeas) and an ambient temperature (Troom) of the coffee machine (2).