Movable Shaft Seal Assembly for Long-Life Handheld Waterproofing
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Solution Overview
Problem
Handheld devices, such as electric toothbrushes, face challenges in achieving long-term waterproofing due to the wear and tear on center shaft sealing members, especially when rotating at larger amplitudes and switching between forward and reverse rotation at higher frequencies.
Innovation Solution
A shaft sealing assembly for handheld devices, comprising a center shaft and a movable sealing assembly with a fixation seat and a movable sealing member made of flexible material. The sealing member is designed to form seals with the front and rear wall surfaces of the sealing slot, reducing wear and enhancing the sealing effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the center shaft rotates at larger rotational stroke and switches between forward and reverse rotation at higher frequency, then the tooth-brushing effect is enhanced, but the waterproof sealing member wears faster and fails sooner
Solution Approach 1:
The sealing system is divided into a stationary sealing member (fixed to the housing) and a movable sealing member (fixed to the center shaft). This segmentation allows each sealing member to be optimized for its specific function: the stationary member provides structural support while the movable member accommodates rotational movements, reducing wear on both components and extending waterproof service life during high-frequency rotation
Solution Approach 2:
The movable sealing member is designed to dynamically follow the rotational movements of the center shaft. It can flexibly adapt to forward and reverse rotation at higher frequencies, maintaining effective sealing contact while accommodating the dynamic operational requirements that enhance tooth-brushing effect
2Device complexity
If a traditional waterproof sealing member is used on the center shaft, then the structure is simple, but the sealing member wears quickly and water leakage occurs
Solution Approach 1:
The sealing structure is segmented into stationary and movable components. The stationary sealing member remains fixed in the housing while the movable sealing member is attached to the rotating center shaft. This segmentation distributes wear across both components rather than concentrating it on a single sealing member, significantly extending sealing durability while maintaining reasonable structural complexity
Solution Approach 2:
The movable sealing member acts as an intermediary between the stationary sealing structure and the rotating center shaft. It transfers rotational movement from the shaft while maintaining sealing contact, reducing direct wear between the shaft and stationary sealing components, thereby improving sealing durability
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 extends the waterproof service life of the shaft sealing assembly and reduces the after-market maintenance rate by minimizing wear between the sealing member and the center shaft, while increasing the sealing area and improving the sealing effect.
Implementation Method 1
The movable sealing member is made of flexible material, the movable sealing member is received in the sleeving hole and extends into the sealing slot, the movable sealing member defines a fixation shaft hole which is sealed to and fixedly sleeves the center shaft, the movable sealing member is sealed to and rotatably mated to the front wall surface and the rear wall surface
Implementation Method 2
a friction coefficient of each of the front wall surface and the rear wall surface is less than a friction coefficient of an outer surface of the fixation seat
Implementation Method 3
the movable sealing assembly further comprises an oily sealing material filled in the sealing compartment, the oily sealing material forms an oil sealing interface between the movable sealing member and the front wall surface and an oil sealing interface between the movable sealing member and the rear wall surface
Data Source
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AI summary
A shaft sealing assembly of a handheld device includes: a center shaft; and a movable sealing assembly, including a fixation seat and a movable sealing member. The fixation seat defines a sleeving hole, an inner circumferential surface of the sleeving hole defines an annular sealing slot, the sealing slot has a front wall surface and a rear wall surface opposite to the front wall surface in an axial direction. The movable sealing member is made of flexible material, the movable sealing member is received in the sleeving hole and extends into the sealing slot, the movable sealing member defines a fixation shaft hole which is sealed to and fixedly sleeves the center shaft, the movable sealing member is sealed to and rotatably mated to the front wall surface and the rear wall surface.