Coffee grinder with a correction system of the dispensed coffee weight
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Solution Overview
Problem
Existing coffee grinders suffer from inaccuracies in dispensing coffee weight due to variable time-of-flight, which is influenced by grain size and mechanical/electronic factors, and are prone to errors from irregular dispensing situations like coffee lumps, leading to unreliable dose control.
Innovation Solution
A coffee grinder with a correction system that ignores outlying weighing operations, corrects time-of-flight weight only after two consecutive errors, applies a correction factor proportional to the error, and allows for refills or restarts the motor based on error thresholds, ensuring accurate dose control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the grinder unit is stopped in advance to account for time-of-flight, then the coffee weight does not exceed the desired weight, but the dosing accuracy deteriorates due to variable time-of-flight depending on grain size and mechanical structure
Solution Approach 1:
The system continuously monitors the actual coffee weight dispensed and uses this feedback to dynamically adjust the time-of-flight compensation value. The control unit compares the measured weight with the target weight and modifies the stop timing accordingly, creating a closed-loop control system that adapts to variations in grain size and mechanical structure.
Solution Approach 2:
The system changes the time-of-flight parameter dynamically based on measured conditions rather than using a fixed value. By adjusting the compensation time based on actual dispensing characteristics, the system adapts to different coffee types and mechanical states, resolving the contradiction between preventing overweight and maintaining precision.
2Measurement precision
If the time-of-flight weight is increased by excess to ensure coffee dose is always lower than desired weight, then dosing accuracy improves by preventing overweight, but coffee waste increases due to frequent refills
Solution Approach 1:
The system uses real-time weight feedback to determine the precise moment to stop grinding, avoiding both overweight and underweight doses. This eliminates the need for excessive time-of-flight compensation and frequent refills, reducing coffee waste while maintaining accuracy.
Solution Approach 2:
The system transitions from a static, conservative time-of-flight value to a dynamic, adaptive stopping point based on actual dispensing conditions. This allows optimal dose delivery without excessive compensation, preventing both waste and inaccuracy.
3Measurement precision
If the average of multiple weighing operations is used to correct time-of-flight weight, then dosing accuracy may improve, but reliability deteriorates due to inclusion of erroneous measurements from coffee lumps
Solution Approach 1:
The system extracts and excludes erroneous measurements from the averaging process. By identifying and removing outlying values caused by coffee lumps or dispensing anomalies, the system calculates a reliable correction value from only valid measurements, maintaining both accuracy and reliability.
Solution Approach 2:
The system introduces an intermediary validation step that filters measurements before they are used for correction. This intermediary layer identifies and excludes erroneous data points, ensuring that only reliable measurements contribute to the time-of-flight correction calculation.
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
The system provides reliable and precise coffee dose dispensing, minimizing errors by distinguishing between small and large variations, and adjusting for inconsistencies in grain size and mechanical structure.
Implementation Method 1
a load cell connected to the support in order to weigh the ground coffee dispensed into the filter holder
Implementation Method 2
When the grinder unit of the coffee grinder is stopped, the grinder unit continues to rotate due to inertia and thus a small amount of ground coffee continues to be dispensed from the dispensing duct
Data Source
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AI summary
A coffee grinder (100) comprises a coffee weight correction system that provides for comparing an error (E) given by a difference between a measured weight (Pm) measured by a load cell (6) and a set weight (Pi) set by a user with four threshold weights (P1, P2, P3, P4); if for two consecutive weighing operations the error (E) is higher than the second weight threshold (P2) or lower than the first weight threshold (P2), a correction algorithm (76) makes a correction by setting a correction factor (C) proportional to the modulus of the error (E) of the last weighing operation.