Coffee Brewing Plunger Control With Rotary Encoder Calibration
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Solution Overview
Problem
Existing coffee brewing devices in hot drinks vending machines lack precision in controlling the pressure exerted by the piston on coffee powder, leading to inconsistent taste quality due to fluctuations in pressure, which affects the extraction of bitter substances.
Innovation Solution
A device with a rotary encoder-controlled electric actuator that moves the piston with calibrated precision, allowing for reproducible pressure settings on the coffee powder by using pulse-based positioning independent of frictional forces and temperature influences, enabling accurate control of the brewing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple electric motor with fixed-time activation is used to move the piston, then the device complexity is reduced, but the manufacturing precision of piston positioning deteriorates
Solution Approach 1:
The patent introduces a rotary encoder that detects the rotational angle position of the motor shaft and feeds this information back to the control device. The control device uses this feedback to calculate the piston's linear position and adjusts the motor activation time accordingly, replacing fixed-time control with closed-loop position control. This resolves the contradiction by maintaining simple motor hardware while achieving high positioning precision through intelligent control.
Solution Approach 2:
The patent replaces the purely mechanical fixed-time motor control system with an electromechanical control system that incorporates rotary encoder feedback. The control device substitutes mechanical timing mechanisms with electronic control based on real-time position detection, achieving precise piston positioning without increasing the complexity of the motor itself.
2Ease of operation
If the piston is moved by a fixed-time electric motor, then the ease of operation is improved, but the measurement precision of piston position deteriorates
Solution Approach 1:
The rotary encoder provides real-time feedback on the motor shaft's rotational angle position, enabling the control device to accurately determine the piston's linear position. This feedback mechanism maintains ease of automated operation while achieving high measurement precision, as the system automatically adjusts based on detected position without requiring manual intervention.
Solution Approach 2:
The rotary encoder acts as an intermediary between the motor's rotational motion and the control device, translating mechanical position into electrical signals that the control device can process. This intermediary enables precise position measurement while keeping the motor operation simple and automated.
3Device complexity
If the piston pressure on coffee powder is not controlled, then the device complexity is reduced, but the taste quality of the coffee beverage deteriorates
Solution Approach 1:
The rotary encoder feedback system enables the control device to precisely control the piston's position and movement, thereby controlling the pressure applied to the coffee powder. This feedback-based control achieves consistent pressure application without requiring complex mechanical pressure regulation mechanisms, resolving the contradiction between device simplicity and taste quality.
Solution Approach 2:
The patent controls the pressure parameter by precisely controlling the piston's linear position through rotary encoder feedback. By changing the piston position parameter based on detected rotational angle, the system achieves consistent pressure application on the coffee powder, improving taste quality without increasing overall device complexity.
Data Source
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AI summary
An apparatus (1) for preparing a coffee beverage comprises a brewing unit (2) with a brewing chamber (6) which is closable by a lid (4) and in which coffee powder (8) having been poured in is compressed by a plunger (14) driven by an electric actuator (10) via a gear mechanism (12), and heated water flows through the compressed coffee powder, and also a control device (18) which controls the electric actuator (10) in accordance with the signals of an angle of rotation sensor (20). The device is characterised in that the control device (18) first moves the plunger (14) against a stop (22) in the ejection position (C) in order to calibrate the angle of rotation sensor (20), then moves the plunger (14) by a predetermined distance in the downwards direction into the pouring-in position (A), the length of which distance corresponds to a first number of pulses of the angle of rotation sensor (20) that is stored in an electronic memory (24) of the electronic control device (18), afterwards moves the plunger (14) by a second distance into the brewing position (B), the length of which distance corresponds to the number of a second number of pulses of the angle of rotation sensor (20) that is stored in the memory (24), and subsequently moves the plunger (14) by a third distance back into the ejection position (A) in which the coffee puck is removed from the plunger (14). The invention furthermore relates to a method for preparing a coffee beverage using the device.