Tension Element Anti-Vibration System for Handheld Tools
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Solution Overview
Problem
Existing handheld work apparatuses, such as chain saws, experience dynamic hardening of rubber buffers under stress, leading to undesired changes in damping characteristics and poor guiding behavior due to the transmission of transverse forces.
Innovation Solution
The use of a tension element, such as a metal cable, bridging the vibration gap between the handle and motor housing, with a spring arranged in series to achieve damping only in the longitudinal direction, preventing the transmission of transverse forces and avoiding dynamic hardening, while being pre-tensioned to compensate for manufacturing tolerances and ensure consistent guiding behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubber buffers are used to bridge the vibration gap, then damping effect is achieved, but dynamic hardening occurs under stress leading to changed damping characteristics
Solution Approach 1:
The patent changes the material parameter from elastomer (rubber) to metal (steel cable), fundamentally altering the stress-strain relationship. Metal cables do not exhibit dynamic hardening like rubber, maintaining consistent damping characteristics across different operating conditions and stress levels.
Solution Approach 2:
The patent replaces the elastomeric damping mechanism with a metal cable tension element. This substitution eliminates the viscoelastic properties of rubber that cause dynamic hardening, while the metal cable provides linear elastic behavior that maintains consistent damping characteristics throughout operation.
2Force
If rubber buffers are used in the middle region of the arm, then forces are transmitted, but transverse forces are not transmitted resulting in poor guiding behavior
Solution Approach 1:
The patent segments the force transmission function by using a cable that only transmits forces along its longitudinal axis. The cable is arranged such that it only carries axial loads, completely eliminating transverse force transmission. This segmentation of force transmission paths provides precise guiding behavior while still allowing necessary force transmission in the longitudinal direction.
3Ease of operation
If a cable is used to bridge the vibration gap, then transverse forces are not transmitted, but additional damping elements parallel to the tension element would transmit transverse forces
Solution Approach 1:
The patent extracts and removes the parallel damping elements that would otherwise be present in the anti-vibration device. By using only the tension element (cable) without additional parallel damping components, the design achieves the desired guiding behavior while maintaining structural simplicity. The cable itself provides sufficient damping through its elastic deformation.
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 provides a robust and simple anti-vibration system that maintains consistent damping and guiding behavior by ensuring forces are transmitted only in the longitudinal direction, avoiding the issues of dynamic hardening and transverse force transmission, resulting in improved damping and operational stability.
Implementation Method 1
a spring arranged functionally in series with the tension element
Implementation Method 2
a damping in the direction of the longitudinal center axis of the anti-vibration device can be achieved
Implementation Method 3
the anti-vibration device including at least one tension element via which the anti-vibration device bridges the vibration gap
Data Source
AI summary
A handheld work apparatus has a drive motor (8) that is held in a motor housing (2). At least one handle (4) is provided, with a vibration gap (12) being formed between the handle (4) and the motor housing (2). The vibration gap (12) permits a relative movement between handle (4) and motor housing (2). The handle (4) is connected to the motor housing (2) via at least one anti-vibration device (13, 14, 15, 16, 31, 49, 50, 63) that bridges the vibration gap (12). The anti-vibration device (15, 16, 31, 49, 50, 63) has a longitudinal center axis (23, 24). The anti-vibration device (15, 16, 31, 49, 50, 63) bridges the vibration gap (12) via at least one tension element. The anti-vibration device (15, 16, 31, 49, 50, 63) also has a spring (17, 32, 33, 51, 55, 72, 73) arranged functionally in series with the tension element.