Nested Planetary Gear Coffee Grinder to Reduce Axial Length and Noise
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Solution Overview
Problem
Fully automatic coffee machines with integral coffee grinders face issues of excessive noise and complex assembly due to a high number of parts, and limited axial construction length, which hampers their integration and operation within the machine's space constraints.
Innovation Solution
The coffee grinder employs a planetary gear system with multiple planetary rods having axially neighboring portions of different diameters, which reduce the axial construction length and noise generation, and are designed to achieve high reduction ratios with a reduced number of parts, using a helical toothing configuration and a stationary ring gear integrated with the gear case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a conventional planetary gear system is used in the coffee grinder, then the reduction ratio is achieved, but the axial construction length becomes too large
Solution Approach 1:
The patent implements nesting by placing the first planetary gear stage inside the second planetary gear stage, with the sun gear of the first stage positioned within the ring gear of the second stage. This nested configuration allows both gear stages to share the same axial space, significantly reducing the overall axial construction length while maintaining the required reduction ratio of at least 10:1
2Productivity
If multiple separate planetary gear stages are used, then the reduction ratio is achieved, but the number of parts increases
Solution Approach 1:
The patent merges two separate planetary gear stages into a single integrated mechanism where the first planetary gear stage is combined with the second planetary gear stage. The planetary rods of the first stage serve dual functions by engaging with both the sun gear and the ring gear, eliminating the need for separate carrier components and reducing the total part count while achieving the required reduction ratio
3Length of moving object
If a compact planetary gear design is used, then the axial length is reduced, but noise generation increases
Solution Approach 1:
The patent employs helical toothing instead of straight toothing for the gear engagement. This parameter change in the gear tooth geometry allows for gradual engagement of teeth, which significantly reduces noise and vibration while maintaining the compact axial construction length. The helical teeth engage progressively rather than simultaneously, smoothing out the mechanical interactions and reducing harmful noise generation
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 results in a quieter, easier-to-assemble coffee grinder with reduced axial length, enabling high reduction ratios and improved operational efficiency within the limited space of fully automatic coffee machines, while maintaining a cost-efficient design.
Implementation Method 1
the planetary gear comprises multiple planetary rods arranged in the circumferential direction around the sun gear, which include a first axial portion meshing with the sun gear and an axially-neighboring, preferably directly adjacent second axial portion with a second diameter different from and preferably smaller than a first diameter of the first axial portion and meshing with a stationary ring gear
Data Source
AI summary
A coffee grinder, in particular for the installation in a fully-automatic coffee machine, including an electric drive motor (1) for driving a grinding unit, wherein a reduction gear (4) formed as a planetary gear is arranged between drive motor (1) and grinding unit, with the sun gear (3) of this planetary gear being drivable by the drive motor (1). The planetary gear includes multiple planetary rods (8) arranged in the circumferential direction around the sun gear (3), these rods including a first axial portion (7) meshing with the sun gear (3) as well as an axially neighboring, second axial portion (9) with a second diameter different from, preferably smaller than, a first diameter of the first axial portion (7), with this second axial portion meshing with a stationary ring gear (11). The toothed racks are arranged to drive an output element (15) with their first axial portions (7).