Hedge Trimmer Engine Inversion for Compact Design

Solution Overview

Problem

Conventional hedge trimmers have a large overall size and high weight due to the traditional arrangement of internal combustion engines, which affects handling and maneuverability.

Innovation Solution

The internal combustion engine is rotated 180° about the crankshaft axis, with the combustion chamber facing the rear handle and the crankcase facing the blade arrangement, reducing the distance between the crankshaft axis and the blade arrangement, resulting in a shorter and lighter design. Additionally, the tank is positioned on the side away from the rear handle, protected by the tubular handle, and anti-vibration elements are used to dampen vibrations between the drive unit and handle housing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the internal combustion engine is arranged with the crankcase facing the rear handle and combustion chamber facing the blade arrangement, then the overall size and weight of the hedge trimmer are reduced, but the traditional arrangement with crankcase facing the blade arrangement provided better structural stability

Engineering Contradiction:

Improveweight of hedge trimmerVSAvoidstructural stability

Core Design Contradiction:

Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies inversion by rotating the internal combustion engine 180 degrees about the crankshaft axis, so that the combustion chamber faces the rear handle and the crankcase faces the blade arrangement, opposite to the conventional arrangement. This inverted configuration reduces the distance between the crankshaft axis and the blade arrangement, thereby reducing the overall size and weight of the hedge trimmer while maintaining structural stability through careful design of the drive unit and housing.

Inventive Principle:

Principle #13The other way round (Inversion)

2Length of moving object

If the internal combustion engine is rotated 180° about the crankshaft axis, then the distance between the crankshaft axis and the blade arrangement is reduced, resulting in a shorter structural length, but the engine arrangement becomes less conventional and may complicate manufacturing

Engineering Contradiction:

Improvestructural length of hedge trimmerVSAvoidease of engine assembly

Core Design Contradiction:

Length of moving objectVSEase of manufacture

Solution Approach 1:

The patent applies inversion by rotating the internal combustion engine 180 degrees about the crankshaft axis, so that the combustion chamber faces the rear handle and the crankcase faces the blade arrangement, opposite to the conventional arrangement. This inverted configuration reduces the distance between the crankshaft axis and the blade arrangement, thereby reducing the overall size and weight of the hedge trimmer while maintaining structural stability through careful design of the drive unit and housing.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the tank is positioned on the side away from the rear handle and protected by the tubular handle, then the tank is better protected from damage, but the overall weight distribution may be affected

Engineering Contradiction:

Improveprotection of tankVSAvoidhandling and maneuverability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies the nesting principle by positioning the tank within the protective envelope of the tubular handle, so that the handle structurally protects the tank from external damage. This nested arrangement integrates the tank into the overall structure without significantly affecting the weight distribution, as the tank is positioned in a space that would otherwise be occupied by other components or empty space.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 arrangement achieves a smaller overall size, improved weight distribution, and enhanced handling by reducing the structural length and weight of the hedge trimmer while providing robust construction and effective vibration damping.

Implementation Method 1

anti-vibration elements are used to dampen vibrations between the drive unit and handle housing

Methodology Applied

Scientific EffectVibration damping: Damping

Data Source

PatentUS8918998B2Hedge trimmer

Publication Date: 2014.12.30 ANDREAS STIHL AG & CO KG

AI summary

A hedge trimmer having a rear handle, a tubular handle and a blade arrangement with at least one cutter bar disposed in a cutter bar plane. An internal combustion engine drives the cutter bars in a reciprocating manner, and has a combustion chamber and a crankshaft mounted in a crankcase so as to be rotatable about an axis of rotation. The combustion chamber faces the rear handle, and the crankcase faces the blade arrangement. The blade arrangement has a longitudinal central axis, and the hedge trimmer has a longitudinal plane that is disposed parallel to the axis of rotation of the crankshaft and transverse to the cutter bar plane. The longitudinal central axis of the blade arrangement lies in the longitudinal plane of the hedge trimmer.