Coffee Grinder Two-Stage Grinding Gap Design for Uniform Grain Size

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Solution Overview

Problem

Existing coffee grinders face challenges in consistently maintaining optimal grain size and suffer from high fines content, leading to blockages and reduced service life due to high wear.

Innovation Solution

The introduction of a second grinding gap downstream of the first, combined with a ceramic or metal grinding ring and element, and a grinding disk, which further comminutes pre-ground material, reducing fines and distributing force for reduced wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single grinding gap is used, then the device complexity is low, but the manufacturing precision of grain size is insufficient and high fines content is generated

Engineering Contradiction:
Improvegrain size uniformityVSAvoidgrinding mechanism structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The single grinding gap is divided into two separate grinding gaps (first grinding gap between grinding ring and grinding cone, second grinding gap between grinding disk and grinding ring) to achieve staged grinding. This segmentation allows coarse grinding in the first gap and fine grinding in the second gap, improving grain size uniformity while reducing fines content.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If a longer grinding path is used, then the manufacturing precision of grain size is improved, but the duration of action increases and productivity decreases

Engineering Contradiction:
Improvegrain size uniformityVSAvoidgrinding efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The grinding path is segmented into two distinct stages with different gap widths. The first grinding gap handles initial size reduction, while the second grinding gap performs final size adjustment. This segmentation allows each stage to be optimized independently, maintaining high productivity while achieving uniform grain size.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the grinding mechanism have different gap widths tailored to specific functions. The first grinding gap has a larger width for coarse grinding, while the second grinding gap has a smaller width for fine grinding. This local quality differentiation improves manufacturing precision without requiring a uniformly long grinding path.

Inventive Principle:
Principle #3Local quality

3Reliability

If a single grinding stage is used, then the device complexity is low, but the reliability is reduced due to high wear

Engineering Contradiction:
Improveservice lifeVSAvoidgrinding mechanism structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The single grinding stage is segmented into two grinding stages with different wear characteristics. The first stage handles the bulk of size reduction, while the second stage performs final refinement. This segmentation distributes wear more evenly across different components, extending the service life of individual parts and improving overall reliability.

Inventive Principle:
Principle #1Segmentation

4Productivity

If a larger grinding gap is used, then the productivity is high, but the manufacturing precision of grain size deteriorates

Engineering Contradiction:
Improvegrinding speedVSAvoidgrain size uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The grinding process is segmented into two stages with different gap widths. The first grinding gap has a larger width that allows high productivity during coarse grinding, while the second grinding gap has a smaller width that ensures manufacturing precision during fine grinding. This segmentation resolves the contradiction by applying different gap sizes to different stages of the process.

Inventive Principle:
Principle #1Segmentation

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

This configuration achieves a more uniform grind size, reduces fines, and extends the service life of the grinder by distributing force and wear evenly over a longer grinding path.

Implementation Method 1

A conveying element, in particular a conveying screw, is preferably arranged above the grinding element, in particular connected to it in a rotationally fixed manner, in order to move coffee beans from an area arranged above the grinder in the direction of the first grinding gap

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Implementation Method 2

a first grinding gap delimited by the grinding ring and the grinding element... in order to grind material to be ground, in particular coffee beans

Methodology Applied
Scientific EffectAbrasion: Abrasion

Implementation Method 3

the grinding ring and grinding element being rotated relative to one another, in particular by means of an electric motor drive

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Implementation Method 4

a second grinding gap downstream of the first grinding gap arranged underneath, in order to further reduce the size of the pre-ground material to be ground exiting from the first grinding gap

Methodology Applied
Scientific EffectAbrasion: Abrasion

Implementation Method 5

a second grinding gap downstream of the first grinding gap arranged underneath, in order to further reduce the size of the pre-ground material to be ground exiting from the first grinding gap (to the desired grain size, in particular for use in brewing units of coffee machines)

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Data Source

PatentEP3202290B1Grinder, mill, device for preparing coffee with a mill and method of milling
Publication Date: 2020.01.08 EUGSTER FRISMAG AG
  • EP3202290B1 patent drawingFigure 1
  • EP3202290B1 patent drawingFigure 2~3
  • EP3202290B1 patent drawingFigure 4~5

AI summary

The invention relates to a grinder for grinding ground material, in particular coffee beans, with a grinding ring (1.2) and a grinding element (1.1) arranged inside the grinding ring (1.2) and preferably designed as a grinding cone (1.1), the grinding ring (1.2) and the grinding element ( 1.1) are rotatable relative to one another about an axis of rotation (R) in order to grind material to be ground in a first grinding gap (SP1) defined by the grinding ring (1.2) and the grinding element (1.1). According to the invention, a second grinding gap (SP2) is arranged downstream of the first grinding gap (SP1) in order to further comminute the pre-ground material to be ground exiting from the first grinding gap (SP1).