Brushless Motor Shaft Support for Saber Saw Impact Mitigation
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Solution Overview
Problem
During cutting work using a saber saw, the plunger with an attached blade can get stuck, applying strong impact to the motion converting portion, leading to deformation or damage of components.
Innovation Solution
A power tool design where the rotation shaft is supported to move axially within the housing, incorporating a shock absorbing portion with an elastic body to mitigate impacts, and a bearing system that allows smooth rotation even during compression, reducing the risk of deformation and damage to the power transmission components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clutch mechanism is provided on the power transmission path to mitigate impact, then the durability of the power transmission portion is improved, but the device complexity increases
Solution Approach 1:
The harmful impact force is extracted and isolated from the power transmission path by allowing the rotation shaft to move axially, separating the impact mitigation function from the power transmission components
Solution Approach 2:
The rotation shaft is designed to be dynamically movable in the axial direction rather than fixed, enabling it to absorb impact through axial displacement while maintaining rotational function
2Reliability
If a clutch mechanism is provided on the power transmission path to mitigate impact, then the durability of the power transmission portion is improved, but the structure becomes less compact and more costly
Solution Approach 1:
The impact mitigation function is merged into the rotation shaft support structure itself, combining the shaft's rotational and axial movement capabilities into a single integrated component that performs both power transmission and shock absorption
Solution Approach 2:
The rotation shaft serves its own protective function by utilizing its axial movability to absorb impact, eliminating the need for separate protective mechanisms and making the system self-protecting
3Object-affected harmful factors
If the rotation shaft is supported to be movable in the axial direction, then the impact on the power transmission portion is reduced, but the precision of power transmission may be affected
Solution Approach 1:
The movement freedom is segmented and restricted to only the axial direction, while rotational precision and radial positioning are maintained through bearing support, separating the degrees of freedom for different functional requirements
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 axial movement of the rotation shaft and the elastic deformation effectively reduce impacts on the power transmission components, enhancing their durability and preventing deformation or damage at a lower cost and with a compact structure, compared to using a clutch mechanism.
Implementation Method 1
a shock absorbing portion including an elastic body configured to be elastically deformed by movement of the rotation shaft portion in the axial direction
Data Source
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AI summary
There is provided a power tool in which impact applied to a power transmission portion can be mitigated to thereby suppress components constituting the power transmission portion from being deformed and damaged. The power tool includes a brushless motor 3 having a rotation shaft portion 31 rotatable about a rotation axis A1, a housing 2 accommodating therein the brushless motor 3, a power transmission portion 6 configured to receive a rotation force of the rotation shaft portion 31 and to transmit a driving force based on the rotation force, and a driven portion 7 configured to be driven by receiving the transmitted driving force. The rotation shaft portion 31 is supported by the housing 2 so as to be movable relative to the housing 2 in an axial direction of the rotation axis A1.