Handheld Power Tool Absorber Reducing Vibrations via Cam-Driven Bending Spring
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Solution Overview
Problem
Handheld power tools, such as hammer drills, generate significant vibrations during operation, leading to user fatigue and potential health issues due to the inability of existing damping systems to effectively mitigate high-frequency vibrations.
Innovation Solution
The integration of an absorber mechanism featuring a bending spring and mass body, driven by a cam disk and wobble drive, which allows for free oscillation and synchronization with the tool's striking mechanism, reducing vibrations by leveraging inertia and minimizing contact with the cam to reduce harmonic excitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a traditional damping system is used to reduce vibrations, then the structure is simple, but the high-frequency vibrations cannot be effectively mitigated leading to user fatigue
Solution Approach 1:
The patent applies mechanical vibration principles by creating a counter-vibration system that generates vibrations opposite to the tool's operating vibrations. The absorber mechanism with bending spring and mass body is driven by a cam disk to produce counter-vibrations that cancel out the harmful high-frequency vibrations from the striking mechanism, effectively mitigating user fatigue while maintaining system simplicity
Solution Approach 2:
The patent implements the counterweight principle by using a mass body in the absorber mechanism that is positioned and driven to create counterbalancing forces. The mass body, combined with the bending spring and cam drive, generates opposing vibrational forces that neutralize the harmful vibrations from the power tool's operation
2Speed
If the cam continuously contacts the bending spring to drive the absorber, then the absorber is driven effectively, but harmonic excitations increase reducing damping efficiency
Solution Approach 1:
The patent applies periodic action by designing the cam disk to contact the bending spring only during specific phases of the absorption cycle. The cam provides periodic impulses rather than continuous contact, driving the absorber effectively during needed phases while allowing free oscillation during other phases, thereby reducing harmonic excitations and improving damping efficiency
Solution Approach 2:
The cam is positioned and timed to apply forces to the bending spring in advance of the main vibration events. By pretensioning the spring and initiating the absorption cycle proactively, the system prepares the absorber to counteract upcoming vibrations more effectively while minimizing unnecessary continuous contact that would generate harmonics
3Object-generated harmful factors
If the absorber oscillates freely without cam contact, then harmonic excitations are minimized, but the absorber cannot be effectively driven to counteract vibrations
Solution Approach 1:
The cam disk is designed to engage the bending spring periodically rather than continuously. During specific angular positions, the cam contacts and drives the absorber to counteract vibrations, while during other positions, the absorber oscillates freely with minimal contact, reducing harmonic excitations while maintaining effective vibration counteraction
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 absorber effectively reduces vibrations by up to 50% of the oscillation amplitude, enhancing user comfort and reducing fatigue by synchronizing with the tool's movement and optimizing the deflection of the bending spring, thus providing a more stable operation.
Implementation Method 1
The absorber preferably oscillates freely for at least 50% of an oscillation, i.e. without contact with the cam and driven only by the inertia of the mass.
Implementation Method 2
The cam, which abuts the counterpiece, pretensions the bending spring in the start-up direction.
Data Source
AI summary
A hand-held power tool includes a tool holder for holding a tool on a working axis, a pneumatic striking mechanism for striking the tool, and an absorber, which includes a bending spring, situated transversely to the working axis, and a mass body. A countershaft is driven by the motor around a rotation axis which runs in parallel to the working axis. A wobble drive for driving the pneumatic striking mechanism is situated on the countershaft. In addition, a cam disk is situated on the countershaft and includes a cam which projects in a start-up direction which runs in parallel to the working axis. The bending spring includes a counterpiece provided relative to the cam. The cam, which abuts the counterpiece, pretensions the bending spring in the start-up direction.