Backpack Blower Base Plate Suction Layout Against Leaf Clogging

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Solution Overview

Problem

Backpack-worn blowers often experience clogged passage openings due to sucked-in leaves, leading to inadequate air supply for the blower, which can result in insufficient airflow and cooling for the drive motor.

Innovation Solution

The design features a large suction surface on the underside of the base plate with strategically placed ribs and suction openings, ensuring that even if leaves are sucked in, they can easily fall off due to low vacuum pressure, and the airflow can be maintained through remaining open suction openings, with the suction area covering at least 50% of the base plate area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single passage opening is provided on the base plate, then the device structure is simple, but the passage opening becomes easily clogged with leaves

Engineering Contradiction:
Improvebase plate structureVSAvoidair supply stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The single passage opening is divided into multiple passage openings on the base plate. Each passage opening is equipped with ribs that form contact surfaces to prevent leaves from blocking the openings. This segmentation allows the air supply system to maintain functionality even if some openings become partially obstructed, as other openings remain open.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the suction area is increased to prevent clogging, then the air supply reliability improves, but the base plate area required increases

Engineering Contradiction:
Improveair supply continuityVSAvoidbase plate area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

Instead of uniformly increasing the entire base plate area, the invention concentrates the suction function in specific local regions where passage openings are strategically positioned. The ribs are locally arranged at the openings to provide leaf-deflecting contact surfaces, maintaining high reliability without requiring a large overall base plate area.

Inventive Principle:
Principle #3Local quality

3Reliability

If ribs are added to prevent leaf clogging, then the passage opening reliability improves, but the device complexity increases

Engineering Contradiction:
Improvepassage opening functionalityVSAvoidbase plate structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The ribs are merged with the base plate structure itself, forming an integrated component rather than a separate attachment. The ribs extend from the base plate to create contact surfaces that naturally deflect leaves away from the passage openings. This merging approach provides reliable leaf prevention while minimizing additional structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 prevents clogging and ensures a consistent airflow supply, even when the drive motor is idling, maintaining efficient operation and cooling of the internal combustion engine without the need for additional fans.

Implementation Method 1

the working air flow is sucked in by the blower through the at least one passage opening

Methodology Applied
Scientific EffectSuction: Suction

Implementation Method 2

leaves or the like that have been sucked in can easily fall off again, since insufficient vacuum is generated to hold the leaves on the suction surface

Methodology Applied
Scientific EffectGravitation: Gravitation

Data Source

PatentEP3239403B1Working device with a drive motor worn on the back and a fan driven by the drive motor
Publication Date: 2019.01.09 ANDREAS STIHL AG & CO KG
  • EP3239403B1 patent drawingFigure 1~3
  • EP3239403B1 patent drawingFigure 4~5
  • EP3239403B1 patent drawingFigure 6~9

AI summary

A work tool carried on the back has a backpack (3) with a back plate (4) and a base plate (5). The base plate (5) has at least one passage opening through which working air is sucked by a fan (13) of the working device from an underside (36) of the base plate (5) to an upper side (35) of the base plate (5). Ribs (33, 34) run on the underside (36) of the base plate (5), the end faces (39) of which face away from the upper side (35) form a contact surface (40) for sucked-up sheets. At least one intake opening (30) is arranged on the underside (36) of the base plate (5), via which the working air flow is sucked in from the environment by the blower (13) through the at least one passage opening. The at least one suction opening (30) lies between the end faces (39) of the ribs (33, 34) in the contact surface and is connected to the at least one flow connection by at least one flow connection on the side of the contact surface (40) facing the fan (13). passage opening connected. The working device has a suction area which is the sum of the areas of all suction openings (30) and which is at least 50% of the area of ​​the underside (36) of the base plate (5).