Chainsaw Side-Mounted Air Filter for Longer Service Life

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Solution Overview

Problem

Existing chainsaws and cut-off saws require frequent cleaning or replacement of air filters due to rapid dirt accumulation, which reduces their operational lifespan and efficiency.

Innovation Solution

The air filter is positioned on the side surface of the outer housing, providing a large filter area and distributing dirt accumulation over a larger area, allowing for reduced dirt entrainment and lower airflow velocity, thereby extending the filter's service life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If the air filter is arranged on the side surface of the outer housing with a large filter area, then the service life of the air filter is extended and dirt accumulation is reduced, but the device complexity increases due to the modified housing structure

Engineering Contradiction:
Improveservice life of air filterVSAvoidhousing structure complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The air filter is arranged on the side surface of the outer housing instead of the top surface, utilizing the lateral dimension of the housing. This repositioning allows the filter to have a larger surface area (at least 10% of the housing surface) while maintaining a compact overall device footprint, thereby extending service life without significantly increasing device complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If the air filter area is increased to at least 10% of the housing surface, then dirt is distributed over a larger area reducing contamination, but the housing design becomes more constrained

Engineering Contradiction:
Improvedirt contamination levelVSAvoidhousing design flexibility
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The housing is designed with a specific side surface configuration that accommodates the large air filter area. The side surface connects the housing top and base and is specifically shaped to provide the required filter area while maintaining manufacturing feasibility. This localized structural adaptation allows the filter to occupy at least 10% of the housing surface without compromising overall manufacturability.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If the air filter is positioned on the side surface for easy accessibility, then maintenance becomes simpler, but the cooling air intake path may be affected

Engineering Contradiction:
Improveair filter accessibilityVSAvoidcooling air intake efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The side surface of the housing is segmented into distinct functional zones: one area dedicated to the air filter arrangement and another area for cooling air intake. This segmentation allows the filter to be easily accessible on the side surface while maintaining an unobstructed cooling air path, as the intake openings are positioned in different locations on the housing structure.

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

The solution results in the air filter needing replacement after extended use, maintaining efficiency and reducing maintenance frequency.

Implementation Method 1

an air filter (12), which is arranged on or in the housing opening

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

the air filter (12) is inclined upwards towards the first side surface (21) of the chainsaw or cut-off saw (1), so that dirt can detach from the air filter (12) and fall off due to gravity

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP4491339B1Motorized chain saw or cut-off grinder
Publication Date: 2026.03.18 ANDREAS STIHL AG & CO KG
  • EP4491339B1 patent drawingFigure 1~2
  • EP4491339B1 patent drawingFigure 3~4
  • EP4491339B1 patent drawingFigure 5~6

AI summary

The invention relates to a chainsaw or cut-off saw with a tool (6) having a tool plane (E) and a control handle (34), wherein a longitudinal direction (50) extends from the control handle (34) to the tool (6). The working device (1) comprises an outer housing (1) with a housing opening (15) for drawing cooling air into the outer housing (5), an electric motor (7) arranged in the outer housing (5) and serving to drive the tool (6), and an air filter (12) arranged on or in the housing opening (15). The chainsaw or cut-off saw can be placed in a parking position on a horizontal plane.The outer housing (5) has a base (17) facing the horizontal plane in the storage position, a housing top (20) opposite the base (17), and a side surface (21) that connects the housing top (20) and the base (17) and limits the working tool (1) along the longitudinal direction (50) perpendicular to the tool plane (E). The air filter (12) is arranged on the side surface (21) of the outer housing (5). In a side view perpendicular to the tool plane (E), the outer housing (5) has an outer housing contour (8) which, in an imaginary projection perpendicular to the tool plane (E), defines an imaginary housing surface (9) onto the tool plane (E). The air filter (12), in an imaginary projection perpendicular to the tool plane (E), has a filter outer contour (38) which defines an imaginary filter surface (39) onto the tool plane (E). The filter area (39) is at least 5% of the housing area (9).