Motor Driven Hand Tool Vibration Isolation Coupling
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Solution Overview
Problem
Motor-driven hand tools, such as percussion drills, transmit harmful vibrations to users, leading to health issues like 'white finger syndrome, due to the transmission of linear and non-linear vibrations through the handgrip, which existing damping arrangements and vibration absorbers fail to adequately mitigate.
Innovation Solution
A coupling arrangement with two distinct coupling strands, one for in-phase and one for anti-phase transmission of machine-side vibrations, utilizing a mass-spring oscillator to cancel out force effects at the handgrip, providing effective isolation and reducing vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a damping arrangement composed of rubber or cellular foamed material is provided between the handgrip and the machine body, then vibration energy is converted into deformation energy, but the vibrations transmitted to the handgrip are not sufficiently reduced
Solution Approach 1:
The patent applies a mass-spring oscillator that generates counter-vibrations to cancel the harmful vibrations transmitted to the handgrip. The oscillator is tuned to resonate at the same frequency as the machine body vibrations but in opposite phase, creating destructive interference that reduces the net vibration transmission.
Solution Approach 2:
The mass-spring oscillator acts as an intermediary element between the machine body and the handgrip. It absorbs and transforms the vibration energy through its oscillatory motion, serving as a mediator that prevents direct transmission of harmful vibrations while maintaining coupling between the components.
2Object-affected harmful factors
If a vibration absorber is used to extract vibration energy from the machine body, then disturbing vibrations excite an additional mass-spring oscillator, but the vibration transmission to the handgrip remains insufficiently reduced
Solution Approach 1:
The patent utilizes a specifically configured mass-spring oscillator that is mechanically coupled to both the machine body and the handgrip. The oscillator is designed with specific mass and spring constants to achieve resonant frequencies that match the dominant vibration frequencies of the machine body, enabling effective vibration cancellation through phase opposition.
Solution Approach 2:
The patent optimizes the parameters of the mass-spring oscillator, including the mass value, spring constant, and damping coefficient, to achieve maximum vibration reduction effectiveness. By carefully selecting these parameters, the system achieves optimal tuning for the specific vibration characteristics of the hand tool.
3Object-affected harmful factors
If the handgrip is substantially isolated from the machine body with respect to machine-side vibrations, then vibration transmission is reduced, but the coupling between handgrip and machine body must be maintained for operational control
Solution Approach 1:
The mass-spring oscillator system selectively filters vibration frequencies while maintaining mechanical coupling. The oscillator absorbs vibrational energy at specific frequencies (matching the machine body's vibration frequencies) while allowing other frequencies and static forces to pass through, thereby maintaining operational control without transmitting harmful vibrations.
Solution Approach 2:
The mass-spring oscillator serves as a selective mediator that allows necessary mechanical coupling for control while blocking harmful vibration transmission. It provides a compliant connection that transmits user control forces effectively while absorbing and isolating the handgrip from machine body vibrations through its oscillatory behavior.
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 significantly reduces vibrations transmitted to the handgrip, thereby minimizing user exposure to harmful mechanical vibrations and potentially preventing health issues like 'white finger syndrome, while also serving as a vibration absorber for the machine body.
Implementation Method 1
a second coupling strand for the substantially anti-phase transmission of machine-side vibrations. The anti-phase condition is realized in a particularly simple manner by means of a mass-spring oscillator
Implementation Method 2
Other approaches are based on the principle of a 'vibration absorber' in which the disturbing vibrations excite an additional mass-spring oscillator, whereby vibration energy is extracted from the machine body
Implementation Method 3
a damping arrangement composed of rubber or cellular foamed material is provided between the handgrip and the machine body of the hand tool. The mode of operation of the damping arrangement is based on the conversion of vibration energy into deformation energy
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A motor-driven hand tool having a machine body (2) and having a handgrip arrangement (3), wherein the handgrip arrangement (3) has a handgrip (4) and a coupling arrangement (5) for coupling the handgrip (4) to the machine body (2), and wherein, in the operational state, in any case, the machine body (2) vibrates, wherein the coupling arrangement (5) has at least two parallel coupling strands (11, 12) and in that the coupling strands (11, 12) are of different configuration such that the force effects which are channeled out at the handgrip side via the individual coupling strands (11, 12) and which are attributed to vibrations introduced at the machine side into the individual coupling strands (11, 12) at least partially cancel one another out.