Rotary Hammer Vibration Attenuation via Telescoping Handle
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Solution Overview
Problem
Rotary hammers generate undesirable vibrations that are transmitted to the user due to the reciprocation mechanism, which can lead to discomfort and reduced efficiency during operation.
Innovation Solution
A rotary power tool design featuring a handle with upper and lower joints that include biasing members to attenuate vibrations along multiple axes, combined with a synchronizing assembly that automatically switches between motor-piston coupling configurations based on tool bit engagement with a workpiece, allowing for controlled axial impacts and reduced vibration transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a reciprocating piston and striker mechanism is used to generate axial impacts, then impact force is improved, but vibration transmitted to the user increases
Solution Approach 1:
The handle is divided into upper and lower portions connected by a telescoping mechanism with multiple degrees of freedom. This segmentation allows different parts of the handle to move independently, absorbing vibration while maintaining impact force transmission to the tool bit.
Solution Approach 2:
The telescoping handle mechanism changes the physical parameters of the system by introducing variable length segments that can extend and retract. This allows the handle to dynamically adjust its configuration, absorbing vibration energy through controlled movement while preserving the axial impact function.
2Stability of the object's composition
If the handle is made rigid for stability, then structural stability is improved, but vibration attenuation capability deteriorates
Solution Approach 1:
The handle transitions from a static rigid structure to a dynamic telescoping mechanism with multiple degrees of freedom. The upper and lower handle portions can move relative to each other, providing vibration attenuation while maintaining structural integrity through controlled mechanical movement rather than rigid fixation.
Solution Approach 2:
The telescoping mechanism acts as an intermediary between the impact-generating mechanism and the user's hand. This intermediate structure absorbs and dissipates vibration energy through its degrees of freedom, protecting the user while allowing the impact force to be effectively transmitted to the workpiece.
3Ease of operation
If the synchronizing assembly is added to automatically switch configurations, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The synchronizing assembly is designed to automatically detect tool bit engagement with the workpiece and switch between drilling and impacting configurations without user intervention. The system serves itself by using the mechanical state of tool bit engagement to trigger the configuration change, eliminating the need for manual controls or complex electronic systems.
Solution Approach 2:
The synchronizing assembly incorporates feedback from the mechanical state of tool bit engagement. When the tool bit contacts the workpiece, this mechanical feedback automatically triggers the synchronizing mechanism to switch to the impacting configuration, and when contact is lost, it returns to the drilling configuration, creating a closed-loop control system.
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 effectively reduces vibration transmission to the user, enhancing comfort and operational efficiency by attenuating vibrations along multiple axes and optimizing the impact mechanism's operation based on tool bit engagement.
Implementation Method 1
Each of the upper and lower joints is operable to attenuate vibration transmitted along the first axis and along a second axis orthogonal to the first axis
Implementation Method 2
The biasing member is operable to bias the handle toward the extended position
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Rotary hammer (10) adapted to impart axial impacts to a tool bit, the rotary hammer comprising: a motor (18); a spindle (22) coupled to the motor for receiving torque from the motor; a piston (34) at least partially received within the spindle for reciprocation therein; a striker (38) received within the spindle for reciprocation in response to reciprocation of the piston; an anvil (42) received within the spindle and positioned between the striker and the tool bit, the anvil imparting axial impacts to the tool bit in response to reciprocation of the striker; a synchronizing assembly (82) operable in a first configuration in which the motor is drivably coupled to the piston for reciprocating the piston, and a second configuration in which the piston is decoupled from the motor; and an actuator (86) operable for switching the synchronizing assembly from the second configuration of the first configuration in response to depressing the tool bit against a workpiece.