Controller for electric motor-driven rotating-blade comminution and mixing
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Solution Overview
Problem
Rotating blade coffee grinders produce broad, poorly defined size distributions with excessive ultrafine particles and dusts, lack a dominant mode, and tend to heat up during prolonged use, failing to meet the quality standards for various brewing methods.
Innovation Solution
A controller for rotating blade grinders that adjusts RMS voltage, duty cycle, activation pulse frequency, and grind time to optimize grind size distributions, reducing ultrafines, defining a single mode, and minimizing heating by intermittently powering the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If continuous grinding is used to achieve adequate comminution, then grinding completeness is improved, but heating of the grinding surfaces and grounds increases
Solution Approach 1:
The patent applies periodic action by using pulsed grinding cycles with intermittent operation. The motor is activated in pulses rather than continuously, allowing cooling periods between grinding cycles. This prevents overheating of the grinding surfaces and grounds while still achieving adequate comminution through repeated short-duration grinding bursts.
2Device complexity
If rotating blade grinding is used for small-batch grinding, then device complexity and cost are reduced, but grind size distribution quality deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying operational parameters of the rotating blade grinder through electronic control. The controller adjusts motor power delivery, pulse duration, and duty cycle to optimize grinding performance. This allows a simple rotating blade grinder to produce grind size distributions comparable to more complex burr-type grinders by precisely controlling the grinding process parameters.
3Productivity
If high motor power is used to reduce grind time, then productivity is improved, but heating of the grounds increases
Solution Approach 1:
The patent uses periodic action with pulsed motor operation to maintain high productivity while preventing overheating. Instead of continuous high-power operation, the motor delivers high power in short pulses followed by cooling intervals. This achieves rapid comminution during active pulses while the intermittent operation prevents excessive heat accumulation in the grounds.
Solution Approach 2:
The patent applies dynamics by making the motor power delivery variable and adaptive. The controller dynamically adjusts the duty cycle and pulse characteristics based on grinding progress and thermal conditions. This allows the system to operate at high power when cooling is sufficient and reduce power when thermal accumulation becomes excessive, optimizing both productivity and temperature control.
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 controller achieves well-defined grind distributions with a dominant mode, reduces ultrafine particles, and prevents overheating, aligning with brewing method requirements and improving coffee quality.
Implementation Method 1
controls RMS voltage, duty cycle, activation pulse frequency, and overall duration of a grind time
Implementation Method 2
perform pulse width modulation of the supply voltage to output an adjusted voltage signal
Data Source
AI summary
A coffee grinder is provided that includes one or more blades; a motor coupled to the one or more blades to drive rotation of the one or blades; and a grind controller that receives a supply voltage; receives a grind setting corresponding to a particular particle distribution; and controls RMS voltage, duty cycle, activation pulse frequency, and overall duration of a grind time of the supply voltage for activation of the motor based on the grind setting, wherein the grind controller generates, from the supply voltage, an adjusted voltage signal of a constant RMS voltage that is supplied to the motor during activation pulses occurring during the overall duration of the grind time to complete operation of the grind setting.