Coffee Brewing Piston Control for Stable Volume Flow
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Solution Overview
Problem
Existing coffee brewing methods, particularly those using piston machines, face challenges in maintaining a consistent volume flow, which can impair the taste and aroma of coffee beverages, especially in the second half of the brewing process.
Innovation Solution
A method that continuously regulates the piston position in the brewing chamber to maintain a constant volume flow by comparing the actual volume flow with a target value and adjusting the piston position as needed, using an impeller meter for measurement and a piston drive for actuation, ensuring optimal extraction behavior and coffee quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a piston machine is used to brew coffee at high pressure, then the extraction efficiency is improved, but the volume flow decreases in the second half of the brewing process, impairing taste and aroma
Solution Approach 1:
The patent applies the dynamics principle by making the piston position adjustable and variable during the brewing process. Instead of a fixed piston position, the system dynamically adjusts the piston position to different setpoints during brewing, allowing the brewing chamber volume to change adaptively. This enables the system to maintain optimal extraction pressure while compensating for flow rate decreases that occur during the brewing process, thereby resolving the contradiction between extraction efficiency and volume flow consistency.
2Device complexity
If the piston position is fixed during brewing, then the device complexity is reduced, but the ability to maintain constant volume flow deteriorates
Solution Approach 1:
The patent implements feedback control by using a flow meter to continuously measure the actual volume flow of water through the brewing chamber. The measured flow rate is fed back to the control unit, which compares it against the target flow rate and adjusts the piston position accordingly. This closed-loop feedback system enables precise volume flow control without requiring overly complex mechanical mechanisms, resolving the contradiction between device complexity and flow control precision.
3Speed
If the brewing chamber volume is reduced to increase pressure, then the extraction speed is improved, but the volume flow of water through the coffee decreases
Solution Approach 1:
The patent resolves this contradiction by dynamically adjusting the piston position during the brewing process. The system initially maintains a smaller brewing chamber volume to achieve high extraction speed and pressure, then progressively increases the chamber volume by moving the piston to maintain adequate water volume flow. This dynamic adjustment allows the system to benefit from both high initial extraction speed and sustained water flow throughout the brewing process.
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 optimizes the brewing process by maintaining a consistent volume flow throughout, enhancing the taste and aroma of coffee beverages and improving overall coffee quality by precisely controlling pressure and flow rates.
Implementation Method 1
When the piston is moved in the brewing chamber, the pressure on the ground coffee in the brewing chamber is either reduced or increased
Implementation Method 2
the volume flow of the water flowing through the brewing chamber being determined as a controlled variable
Data Source
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Figure 2
AI summary
Method for producing a coffee drink from ground coffee by means of a brewing process on a coffee machine with a control device (22) and with a brewing cylinder (2) in which a piston (3) is movably arranged, which has a piston drive (11) so that the volume a brewing chamber (6), the brewing process having at least the following method steps: S1: a quantity of ground coffee (7) is filled into the brewing chamber (6); S2: water is passed through the ground coffee filled into the brewing chamber (7) in order to prepare the coffee drink, with a volume flow, in particular the volume flow of the water flowing through the brewing chamber, being determined as a controlled variable and compared with a volume flow target value; and S3: if deviations from a specified volume flow target value are determined in step S2, the position of the piston (3) in the brewing chamber is changed as a control variable in order to adjust the volume flow to the volume flow target value, with steps S2 and S3 being repeated during the brewing process.