Spring-Loaded Axle Sealing for Vacuum Tightening Tools
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Solution Overview
Problem
Electrical power tools with internal vacuum arrangements face challenges in maintaining proper sealing due to varying pressure affecting rubber seals and causing grease removal, leading to reduced functionality and lifespan.
Innovation Solution
A sealing arrangement featuring a sealing element that bears against a housing shoulder and a rotating axle, with a spring providing a controlled force to maintain a static seal against the axle and a dynamic seal against the housing, minimizing friction and accommodating tolerance and wear variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rubber seals are used in sealing bearings under varying vacuum pressure, then sealing is provided, but the varying pressure negatively affects the rubber seals thereby decreasing sealing performance and the vacuum causes removal of grease from bearings impairing functionality and decreasing lifetime
Solution Approach 1:
The harmful vacuum pressure is excluded from the bearing chamber by providing a separate sealing arrangement that prevents vacuum from acting on the bearing grease and seals, thereby preserving bearing functionality and lifetime while maintaining sealing in the vacuum chamber
Solution Approach 2:
The tool housing is divided into separate chambers: a vacuum chamber for the sealing element and a bearing chamber at atmospheric pressure, allowing bearings to operate without vacuum exposure while the sealing element operates under vacuum conditions
2Reliability
If sealing elements are pressed against housing shoulders to provide sealing, then sealing performance is improved, but friction forces increase affecting torque accuracy
Solution Approach 1:
The sealing element is designed to rotate together with the axle rather than being stationary, creating a dynamic sealing arrangement that reduces friction and eliminates torque variability while maintaining effective sealing between pressure zones
Solution Approach 2:
The sealing mechanism transitions from static pressing force to dynamic rotational contact with controlled spring pressure, changing the operational parameters to reduce friction while maintaining sealing effectiveness
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
This design enhances sealing performance and tool lifespan by maintaining low, constant friction, improving torque accuracy and extending tool life, especially in low-torque applications.
Implementation Method 1
the spring is adapted to at a first end bear against a shoulder formed in the sealing element and at a second end bear against a supporting element arranged on the axle, such that a force is exerted on the sealing element urging the sealing element against the shoulder formed in the housing
Implementation Method 2
a second portion adapted to bear against a portion of an outer surface of a rotating axle of the tool
Data Source
AI summary
A handheld electric tightening tool includes a housing and a sealing arrangement. The sealing arrangement is adapted to seal a first portion of the housing from a second portion of the housing and includes a sealing element and a spring. The sealing element includes a first portion adapted to bear against a shoulder formed in the housing, and a second portion adapted to bear against a portion of an outer surface of a rotating axle of the tool. The spring is adapted to at a first end bear against a shoulder formed in the sealing element and at a second end bear against a supporting element arranged on the axle, such that a force is exerted on the sealing element urging the sealing element against the shoulder formed in the housing.