Rotary Power Tool Handle Isolation for Resonant Vibration Damping
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Solution Overview
Problem
Portable grinding tools with electric motors experience significant resonant vibrations due to their longer rotor shafts, which shake the tool at high operating speeds, unlike pneumatic tools with shorter shafts.
Innovation Solution
A vibration damping assembly is integrated between the motor housing and handle, comprising elastomeric dampers and coupling portions to attenuate vibrations, along with a low friction wear member to prevent abrasion and a balanced rotor assembly to reduce vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electric motors with longer rotor shafts are used, then the tool can achieve high operating speeds, but the shaft experiences resonant vibrations that shake the tool
Solution Approach 1:
The patent introduces a vibration damping assembly as an intermediary component between the motor housing and handle. This assembly includes elastomeric dampers that absorb and dissipate vibrational energy, preventing the transmission of resonant vibrations from the motor shaft to the tool handle while allowing the motor to operate at high speeds
2Object-affected harmful factors
If a vibration damping assembly is added to reduce vibrations, then vibration transmission is reduced, but the device complexity increases
Solution Approach 1:
The vibration damping assembly is integrated into the existing motor housing and handle structure. The elastomeric dampers are positioned within the coupling between these components, merging the vibration damping function with the structural connection rather than adding separate, standalone vibration reduction mechanisms
Solution Approach 2:
The patent uses elastomeric dampers made from flexible material that can deform to absorb vibrational energy. These elastomeric components serve as flexible elements that provide vibration damping while maintaining the structural integrity of the connection between motor housing and handle
3Device complexity
If the handle is directly coupled to the motor housing, then the device complexity is reduced, but abrasion occurs between the housing and battery pack
Solution Approach 1:
The elastomeric dampers serve as intermediary elements between the motor housing and handle assembly. These dampers provide a protective interface that prevents direct contact and friction between the housing and battery pack, thereby reducing abrasion while maintaining a relatively simple overall device structure
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 tool vibrations and prevents abrasion, enhancing user comfort and tool longevity by minimizing vibration transmission and wear.
Implementation Method 1
an elastomeric damper captured between the first coupling portion and the second coupling portion
Implementation Method 2
an elastomeric damper captured between the first coupling portion and the second coupling portion
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A power tool includes a motor housing, a motor, a handle coupled to the housing, and a vibration damping assembly. The motor is positioned in the motor housing and configured to rotatably drive an output shaft. The vibration damping assembly is positioned between the motor housing and the handle. The vibration damping assembly includes a first coupling portion defined by the motor housing, a second coupling portion defined by the handle, and an elastomeric damper captured between the first coupling portion and the second coupling portion. The first coupling portion includes a boss having a flange and a first groove. The second coupling portion defines an opening and includes first and second ribs extending into the opening and spaced apart along a longitudinal axis of the handle. The first and second ribs define a second groove therebetween. The damper occupies the first and second grooves.