Coffee Mill Grinder Distance Sensing for Precise Dose Control
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Solution Overview
Problem
Existing coffee machines struggle to accurately control the grind size of coffee beans, leading to inconsistent flavor profiles due to variability in coffee type, roast, moisture content, and grinder wear, resulting in imprecise coffee dosing and mismatched user preferences.
Innovation Solution
A coffee machine equipped with a control unit, sensors for motor speed and grinder distance, and an algorithm to calculate the precise number of turns for the grinder motor, ensuring the correct coffee dose is achieved, along with manual adjustment options for fine-tuning flavor and infusion parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the grinding time is defined by the control unit based on user selection, then the beverage preparation is automated, but the dose of ground coffee becomes imprecise due to variability in coffee type, moisture content, and grinder wear
Solution Approach 1:
The system uses a sensor to detect the actual number of grinder revolutions and feeds this information back to the control unit. The control unit compares the detected revolutions with the target revolutions calculated from the algorithm, and adjusts the grinding process accordingly to achieve precise dosing despite variations in coffee properties and grinder wear.
Solution Approach 2:
The system dynamically adjusts grinding parameters (number of revolutions, grinding time) based on detected conditions. The algorithm calculates the required number of revolutions based on the selected beverage type and detected grinder position, allowing the system to adapt to different coffee types, moisture contents, and grinder wear levels while maintaining precise dosing.
2Ease of operation
If manual adjustment of grinder gap is used to define particle size, then the user can control grind coarseness, but the correct dose of ground coffee at given particle size cannot be consistently achieved due to variability in coffee and grinder conditions
Solution Approach 1:
The sensor provides feedback on the actual number of grinder revolutions, allowing the control unit to compensate for variations in coffee properties and grinder wear. This feedback mechanism ensures that the precise number of revolutions required for correct dosing is achieved, regardless of manual grinder gap adjustments or changes in coffee characteristics.
Solution Approach 2:
The system replaces reliance on manual mechanical adjustment alone with an automated control system that uses sensors and algorithms to precisely control the grinding process. The control unit calculates and enforces the exact number of revolutions needed, substituting manual estimation with automated precision control.
3Device complexity
If the grinder motor runs for a fixed duration to produce ground coffee, then the process is simple to control, but the dose of ground coffee is imprecise and does not consistently match user selection
Solution Approach 1:
The control unit uses sensor feedback to monitor the actual number of grinder revolutions and adjusts the motor running time accordingly. Instead of using a fixed duration, the system continuously monitors revolutions and stops the motor when the target number of revolutions is reached, ensuring precise dosing while maintaining relatively simple control logic.
Solution Approach 2:
The system uses the sensor to automatically detect when the correct number of revolutions has been achieved and self-regulates the motor shutdown. This eliminates the need for complex external timing mechanisms while achieving precise dosing through automated self-control based on actual grinder performance.
Data Source
Figure 1~2
AI summary
The coffee machine (1) comprises at least a control unit (3), a pump (4) for supplying infusion water, a boiler (6) for heating the infusion water, an infusion unit (7), a coffee mill (2), user interface means (8) comprising at least a selector (9) for a beverage and/or a ground coffee dose, the coffee mill (2) comprising in turn a hopper (10) for coffee beans, a rotating grinder (11) and a non-rotating grinder (12), a motor (13) for directly or indirectly driving the rotating grinder (11) in relative rotation, and means for adjusting the distance between the grinders (11, 12), there being further provided a first sensor (23) for detecting the number of turns and/or speed of the motor and/or of the rotating grinder (11), and a second sensor (22) for detecting the distance between the grinders (11, 12), the control unit (3) storing an algorithm for calculating the correct dose of ground coffee, the calculation algorithm being configured to receive as an input from the selector (9) the value of ground coffee selected and from the second sensor (22) the value of the distance between the grinders (11, 12) so as to automatically generate as an output the value of the number of total turns that the motor (13) must perform to obtain the correct dose of ground coffee, the control unit (3) being configured to receive as an input from the first sensor (23) the current value of the number of turns and/or of the speed of the motor (13) and/or of the rotating grinder (11) so as to produce a stop signal for stopping the motor (13) upon reaching said number of total turns.