Coffee Grinder Dosing Control Using Actuator Current Feedback
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Solution Overview
Problem
Existing automatic coffee machines face challenges in accurately and consistently measuring the amount of ground coffee dispensed due to factors like wear, grind size variability, and environmental conditions, leading to inconsistent beverage quality and potential machine malfunction.
Innovation Solution
An automatic coffee machine with an electronic control unit that adjusts the grinding time based on real-time feedback from the electric actuator's current absorption during brewing chamber closure, using a closed-loop control system to correct the amount of ground coffee dispensed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed time or fixed number of revolutions is used for grinding, then the control system is simple, but the amount of ground coffee cannot be accurately controlled due to component wear and grind size variability
Solution Approach 1:
The patent implements feedback control by measuring the electric current absorbed by the actuator during brewing chamber closure. This current measurement serves as an indicator of the actual amount of ground coffee present, allowing the system to adjust the grinding time in subsequent cycles to compensate for variations in grind size and component wear, thereby achieving accurate dosing without complex mechanical measurement systems
Solution Approach 2:
The patent replaces direct mechanical measurement of ground coffee amount with an electrical measurement approach. Instead of using complex mechanical sensors or volumetric chambers, the system uses electric current absorption measurement during the closure process to indirectly determine the amount of ground coffee, simplifying the device while improving measurement accuracy
2Measurement precision
If fixed volume pre-load chamber is used, then direct control of ground coffee volume is achieved, but additional components and manual adjustment systems are required
Solution Approach 1:
The patent extracts the measurement function from a separate volumetric pre-load chamber system and integrates it into the existing closure actuator measurement. By using the electric current measurement already available during the closure process, the system eliminates the need for dedicated volumetric measurement components while maintaining accurate control of ground coffee amount
Solution Approach 2:
The patent makes the electric actuator serve multiple functions: it not only closes the brewing chamber but also provides measurement data through its current absorption characteristics. This multi-functionality eliminates the need for separate measurement systems, reducing device complexity while maintaining dosing accuracy
3Extent of automation
If electric current feedback is used to adjust grinding, then automatic adjustment is achieved, but fixed thresholds become invalid due to component wear and greasing condition variations
Solution Approach 1:
The patent implements dynamic threshold adjustment where the reference current values are not fixed but are periodically updated based on actual measurements. The system adapts to changing conditions such as component wear and greasing variations by learning the actual current characteristics during operation, maintaining reliable control despite environmental changes
Solution Approach 2:
The patent changes the control parameters from fixed current thresholds to dynamically adjusted reference values that adapt to component condition. By continuously or periodically updating the reference current based on actual measurements during closure operations, the system maintains accurate dosing control even as components wear or greasing conditions change
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
Ensures precise and stable measurement of ground coffee over time, maintaining consistent beverage quality and preventing machine over-stress by adjusting grinding time based on previous cycle data and environmental factors.
Implementation Method 1
measuring a value indicative of an electric current absorbed by the electric actuator during a closing of the brewing chamber
Implementation Method 2
the electric actuator that closes the brewing assembly and compresses the ground coffee contained therein
Data Source
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AI summary
An automatic coffee machine (1) comprising a brewing assembly (2) with a brewing chamber (11) designed to contain a quantity of ground coffee and an electric actuator, which can be operated to cause the brewing chamber (1) to be opened and closed; a grinder (3) comprising an electric actuator operable to cause coffee beans to be ground and ground coffee to be produced; a hydraulic circuit (4) to supply water to the brewing assembly (2) to prepare a coffee beverage by brewing the ground coffee in the brewing chamber (11) and comprising a water pump (7) and a water flow meter (5) to measure a quantity of water supplied by the water pump (5); a sensory system (15) to sense and output an output indicative of different operating quantities of the automatic coffee machine (1) and comprising an electric current (C) absorbed by the electric actuator (14) of the brewing assembly (2), a flow rate (F) of the dispensed coffee beverage and an electric power (P) absorbed by the water pump (5); a user interface (16) to allow a consumer to request a beverage to be dispensed; and an electronic control unit (17) designed to interface with the sensory system (15) and the user interface (16) to receive outputs thereof and with the brewing assembly (2), the grinder (3) and the water pump (7) to provide commands thereto. The electronic control unit (17) is further designed to compute a coffee bean grinding time TN for which the grinder (3) is to be operated in a coffee beverage preparation cycle to produce a quantity of ground coffee necessary to produce a selected coffee beverage, and to control the grinder (3) accordingly. The electronic control unit (17) is further designed to compute the coffee bean grinding time TN for which the grinder (3) is to be operated in a coffee beverage preparation cycle based on the following quantities: a coffee bean grinding time TN-1 used in a previous coffee beverage preparation cycle; a difference ΔCurrentN-1 between an electric current C absorbed by the electric actuator (14) of the brewing assembly (2) during a closing of the brewing chamber (11) in a previous coffee beverage preparation cycle in which the brewing chamber (11) was loaded with ground coffee, the electric current CE absorbed by the electric actuator (14) of the brewing assembly (2) during the closing of the brewing chamber (11) in a previous coffee beverage preparation cycle in which the brewing chamber (11) was empty, and a maximum admissible limit CL for the electric current absorbed by the electric actuator (14) of the brewing infuser (2) during the closing of the brewing chamber (11); a difference ΔFlow N-1 between a measured flow rate F of the dispensed coffee beverage at the end of a previous coffee beverage preparation cycle and a target flow rate FA of the dispensed coffee beverage; and a difference ΔPumpN-1 between an electric power P absorbed by the water pump (5) at the end of a previous coffee beverage preparation cycle and a target electric power PA absorbed by the water pump (5).