Shredder Feed Tube Segmentation for Branch Kickback

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Solution Overview

Problem

Existing garden shredders with dual feed tubes are costly and often produce suboptimal chopping results when branches are fed through the vertical tube, leading to kickback effects.

Innovation Solution

A single feed tube design with a lower section parallel to the axis of rotation and an inclined section that guides material at an angle, allowing both chopped material and branches to be fed vertically and obliquely respectively, ensuring perpendicular impact on the cutting disc for efficient shredding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a dual feed tube design is used, then both chopped material and branches can be fed, but the construction cost increases and operation becomes more complex

Engineering Contradiction:
Improveability to feed different materialsVSAvoidnumber of feed tubes
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The feed tube is segmented into two functional sections: a lower section that is approximately parallel to the axis of rotation for feeding chopped material, and an inclined section for feeding branches. This segmentation allows different materials to be fed through a single tube structure, achieving versatility without requiring separate tubes for each material type.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The feed tube is designed to serve multiple functions by accommodating both chopped material and branches through its different sections. The lower parallel section handles chopped material while the inclined section handles branches, making a single feed tube universal for feeding different types of waste materials to the shredding device.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Productivity

If a vertical feed tube is used, then chopped material can be fed efficiently, but branches cannot be fed effectively and kickback occurs

Engineering Contradiction:
Improvechopping efficiencyVSAvoidability to feed branches
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The feed tube is divided into a lower section parallel to the axis of rotation for efficient chopped material feeding and an inclined section for branch feeding. This segmentation allows each section to optimize its function: the parallel lower section maintains vertical feeding efficiency for chopped material while the inclined section enables effective branch feeding without kickback.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different sections of the feed tube have different orientations to match the specific feeding requirements of different materials. The lower section has a parallel orientation optimized for chopped material, while the inclined section has an angled orientation optimized for branches, providing local quality optimization for each material type.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If an inclined feed tube is used, then branches can be fed effectively, but chopped material does not impact the cutting disc perpendicularly

Engineering Contradiction:
Improvebranch feeding efficiencyVSAvoidshredding efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The feed tube is segmented into a lower parallel section for chopped material and an inclined section for branches. The lower section maintains a parallel orientation to the axis of rotation, ensuring that chopped material impacts the cutting disc perpendicularly for optimal shredding efficiency, while the inclined section provides effective branch feeding.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lower section of the feed tube is designed with a specific local quality - being parallel to the axis of rotation - to ensure perpendicular impact of chopped material on the cutting disc. This local orientation optimization maximizes shredding efficiency for chopped material while the inclined section handles branch feeding separately.

Inventive Principle:
Principle #3Local quality

4Manufacturing precision

If the lower section length is increased, then vertical impact of chopped material is improved, but the feed tube becomes more complex

Engineering Contradiction:
Improvevertical impact accuracyVSAvoidfeed tube geometry
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention specifies a parameter relationship for the lower section length to diameter ratio (at least 20%, preferably at least 25%). This parameter optimization ensures that the lower section is long enough to guarantee vertical impact of chopped material on the cutting disc while avoiding excessive length that would increase complexity. The inclined section length is also optimized relative to the diameter (at least 120%, preferably at least 175%) to ensure proper branch feeding angle.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2014370B1Shredder
Publication Date: 2018.11.14 ANDREAS STIHL AG & CO KG
  • EP2014370B1 patent drawingFigure 1~2

AI summary

The shredder has a drive unit that drives a reduction device about a rotation axis and a feed tube (3) for delivering the material to be shredded to the reduction device. The feed tube has a lower section (4) whose central longitudinal axis (13) is arranged approximately parallel to the axis of rotation (9) of the reduction device and an inclined section (5) whose central longitudinal axis (14) is inclined to the axis of rotation of the reduction device.