Motor Deceleration Vent Slit Structure Against Rainwater Intrusion
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Solution Overview
Problem
Existing motors with deceleration mechanisms are susceptible to rainwater intrusion through vent holes, particularly when installed in high-temperature environments and exposed to water, which can compromise the integrity of the housing and its components.
Innovation Solution
A motor with a deceleration mechanism featuring a housing with a communication hole, a cylindrical member extending in the axial direction, and slits in the cylindrical member with narrower opening widths on the outer side, designed to prevent rainwater intrusion and facilitate quick discharge of any water that enters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a vent hole is provided in the housing to allow air flow for pressure equalization, then the breathing function is improved, but rainwater intrusion risk increases
Solution Approach 1:
The vent hole is segmented into multiple slits in the cylindrical member, creating numerous small openings instead of a single large hole. This segmentation allows air to pass through while reducing the risk of rainwater intrusion, as water droplets are less likely to penetrate through multiple narrow slits simultaneously
Solution Approach 2:
The slits are designed with asymmetric opening widths, where the opening width varies along the axial direction of the cylindrical member. The opening width is narrower at one end and wider at the other end, creating an asymmetric geometry that facilitates air flow in both directions while preventing rainwater from entering the housing through capillary action or pressure differential
2Reliability
If the opening width of slits is made narrower to prevent rainwater intrusion, then water exposure reliability is improved, but air flow capability deteriorates
Solution Approach 1:
The solution transitions from considering only the cross-sectional area of the vent hole to incorporating the axial dimension by creating slits with varying opening widths along the axial direction. This dimensional approach allows the slits to maintain sufficient air flow area while the asymmetric geometry prevents rainwater intrusion through capillary pressure effects
Solution Approach 2:
The opening width parameter of the slits is changed along the axial direction, creating a gradient from narrower to wider openings. This parameter variation optimizes the balance between preventing rainwater intrusion (narrower openings) and maintaining air flow capability (wider openings), allowing the system to achieve both water exposure reliability and adequate ventilation
Data Source
AI summary
A cylindrical member 93 is provided with a pair of slits 93a, 93b extending in the axial direction of the cylindrical member 93. The opening widths of the pair of slits 93a, 93b in the circumferential direction of the cylindrical member 93 are narrower on the outside (opening widths W2, W4) of the cylindrical member 93 than on the inside (opening widths W1, W3) thereof. This makes it possible to prevent rainwater and the like from reaching a communication hole 91 inside the cylindrical member 93 and quickly discharge the rainwater and the like intruded into the inside of the cylindrical member 93 to the outside of the cylindrical member 93. Accordingly, it is possible to effectively prevent the rainwater and the like from intruding into the inside (hollow portion) of a gear cover 80, thereby enabling to improve a water exposure reliability.