No-bean detection for coffee bean grinder

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Solution Overview

Problem

Coffee bean grinders lack effective detection methods for determining when the hopper is empty, leading to potential motor overheating and incorrect assumptions about gear stalling, as existing methods like optical sensors and current monitoring are prone to errors due to dust accumulation and increased current draw when gears are stuck.

Innovation Solution

A coffee bean grinder system that includes a motor stall detection sensor to monitor operating parameters, a weight sensor to measure coffee grounds, and a controller to determine if no beans are present in the hopper by detecting no change in weight over a predetermined time without motor stall conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical sensors are used to detect empty hopper, then detection capability is provided, but dust accumulation covers the sensor and causes detection errors

Engineering Contradiction:

Improveempty hopper detection accuracyVSAvoiddust accumulation on sensor

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces optical sensors with a motor stall detection mechanism that monitors motor operating parameters (current, voltage, speed). This substitution eliminates the need for optical sensors that are susceptible to dust accumulation, using instead electrical parameter monitoring that is not affected by coffee dust in the hopper environment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If motor current monitoring is used to detect empty hopper, then detection is provided, but increased current draw when gears are stuck leads to incorrect detection

Engineering Contradiction:

Improveempty hopper detection accuracyVSAvoiddetection system reliability

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the detection process into multiple independent monitoring functions: motor current monitoring, motor speed monitoring, and weight sensor monitoring. By dividing the detection task into separate functions, the system can distinguish between current increases due to empty hopper versus current increases due to gear stalling, improving detection accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system uses feedback from multiple sensors (motor current, motor speed, weight sensor) to continuously monitor system state. The controller processes feedback from these sensors to determine whether the motor is stalled or the hopper is empty, enabling accurate detection by comparing multiple feedback signals rather than relying on a single parameter.

Inventive Principle:

Principle #23Feedback

3Productivity

If motor runs under no load conditions, then grinding capability is maintained, but motor overheating occurs

Engineering Contradiction:

Improvegrinding operation continuityVSAvoidmotor temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The system performs preliminary detection of empty hopper conditions before the motor runs extended periods under no load. By detecting the empty hopper state early through motor parameter monitoring and weight sensing, the controller can stop the motor before overheating occurs, preventing the harmful thermal effect while maintaining productivity when beans are present.

Inventive Principle:

Principle #10Preliminary action

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

Effectively prevents motor overheating and accurately detects when the hopper is empty, ensuring safe operation and efficient grinding by distinguishing between empty hopper and motor stall conditions.

Implementation Method 1

monitoring with a motor stall detection sensor at least one operating parameter of the motor

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

measuring using a weight sensor a weight of coffee grounds that have been ground by the grinding apparatus

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentUS9675211B2No-bean detection for coffee bean grinder

Publication Date: 2017.06.13 KAZ EUROPE SA

AI summary

A method for detecting a state of a coffee bean grinder includes providing a supply voltage to a motor of a grinding apparatus, and monitoring with a motor stall detection sensor at least one operating parameter of the motor. The method further includes determining whether a motor stall has been detected based on monitoring the at least one operating parameter. The method also includes measuring using a weight sensor a weight of coffee grounds that have been ground by the grinding apparatus, and determining that no beans are present in a hopper that feeds coffee beans to the grinding apparatus when no motor stall has been detected and no change in weight has been detected at the weight sensor for a predetermined amount of time. A coffee bean grinder is also disclosed.