Reciprocating Tool Balancer Support for Low Noise and Vibration
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Solution Overview
Problem
Reciprocating tools with brushless motors face issues of abnormal noise and vibration due to rigidity shortages in motor housings and deviations in the positional relationship between crank members and balancers under excessive loads, leading to impact-generated deviations and noise.
Innovation Solution
The tool design supports the balancer solely by an eccentric pin within the housing, and employs an integrally molded cylinder-type motor housing to enhance rigidity, reducing noise and vibration while ensuring easy mounting and improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact brushless motor is employed to reduce motor housing diameter, then the size of the motor housing is reduced, but the rigidity of the motor housing becomes insufficient
Solution Approach 1:
The motor housing is divided into two half housings that are assembled together, allowing for easier assembly and disassembly while maintaining structural integrity. This segmentation enables the housing to be manufactured with optimized rigidity features without requiring a completely different design approach.
Solution Approach 2:
Ribs are added to the inner surface of the motor housing in the radial direction, creating structural reinforcement without increasing the overall diameter. This dimensional approach allows rigidity enhancement while maintaining the compact size requirement.
2Reliability
If the balancer is supported by a bearing disposed on the housing inner surface, then the balancer is stably supported, but impact from excessive load causes deviation in positional relationship between crank member and balancer, generating abnormal noise and vibration
Solution Approach 1:
The bearing is removed from the support structure for the balancer's rotational center. Instead of using a bearing that can deviate under impact, the balancer is directly supported by the housing inner surface through a press-fit structure, eliminating the intermediate component that could cause positional deviation.
Solution Approach 2:
The support function is merged directly into the housing structure. The housing inner surface itself provides the support for the balancer's rotational center through a press-fit connection, combining the housing and support function into a single integrated structure that resists impact without deviation.
3Ease of manufacture
If a half-split motor housing structure is employed, then assembly and disassembly is easier, but the rigidity of the motor housing is insufficient
Solution Approach 1:
The motor housing is divided into two half housings that are assembled together, allowing for easier assembly and disassembly while maintaining structural integrity. This segmentation enables the housing to be manufactured with optimized rigidity features without requiring a completely different design approach.
Solution Approach 2:
Ribs are added to the inner surface of the motor housing in the radial direction, creating structural reinforcement without increasing the overall diameter. This dimensional approach allows rigidity enhancement while maintaining the compact size requirement.
Data Source
AI summary
A reciprocating tool includes a motor, a reciprocating member, and a crank mechanism. The motor is disposed in a housing. The reciprocating member projects from the housing. The crank mechanism converts rotation of a rotation shaft of the motor into reciprocation of the reciprocating member. The crank mechanism rotates around an axis in a lateral direction by rotation transmission from the rotation shaft, and the crank mechanism includes a crank member having an eccentric pin, a connecting rod coupling the eccentric pin to the reciprocating member, and a balancer coupled to the eccentric pin, and the balancer is supported by the eccentric pin alone in the housing.