Seal Structure Radial Position Stabilization
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Solution Overview
Problem
The existing seal structures for motor reduction gears face issues with unstable radial positioning and distortion of sealing members during assembly, leading to compromised sealing performance when integrated with the cover using outsert molding, as the protrusions tend to contract radially inward and lose contact with the crimping surface.
Innovation Solution
A seal structure with a projecting portion between anchor portions in the recessed portion of the cover, which stabilizes the radial position of the protrusion and allows for compressive deformation, ensuring proper contact with the case, and is formed integrally with the cover using outsert molding to enhance sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sealing member is integrated with the cover by outsert molding, then the number of parts is reduced and assembly is simplified, but the radial position of the protrusion becomes unstable and distortion occurs in the circumferential direction
Solution Approach 1:
The sealing member is segmented into multiple functional portions: a protrusion for sealing contact, anchor portions for fixation, and projecting portions for positional stabilization. This segmentation allows each portion to perform its specific function optimally while maintaining overall structural integrity during the molding process.
Solution Approach 2:
The projecting portions are pre-formed in the mold along with the sealing member before assembly. This preliminary formation ensures that the radial position of the protrusion is stabilized during the molding process itself, preventing distortion that would occur if positioning were attempted after assembly.
2Ease of manufacture
If the resin is removed from the second cavity before complete solidification, then the molding process is simplified, but the protrusion contracts radially inward and loses contact with the crimping surface
Solution Approach 1:
The projecting portions are designed to provide compensatory support that counteracts the radial contraction of the protrusion during solidification. This beforehand cushioning ensures that even when the resin is removed before complete solidification, the protrusion maintains sufficient contact pressure with the crimping surface for reliable sealing.
Solution Approach 2:
The design changes the physical parameters of the sealing structure by adding projecting portions that alter the stress distribution and deformation characteristics of the protrusion during solidification, allowing it to maintain contact despite early resin removal.
3Productivity
If multiple through-holes are provided in the recessed portion, then the resin can be supplied more effectively, but the structural integrity of the recessed portion may be compromised
Solution Approach 1:
The resin supply system is segmented into multiple gates corresponding to multiple through-holes, allowing resin to be supplied to different regions of the sealing member simultaneously. This segmentation improves filling efficiency while the strategic placement and sizing of through-holes maintains structural integrity.
Solution Approach 2:
The through-holes are strategically positioned and sized to provide optimal resin flow to different regions of the sealing member while maintaining sufficient structural strength in the recessed portion. Each through-hole location is optimized for its specific functional requirement.
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 configuration prevents distortion and improves sealing performance by maintaining the radial position of the protrusion, reducing the number of parts and simplifying assembly, while ensuring effective sealing between the case and cover.
Implementation Method 1
the resin with which the second cavity 6a is filled (that is, the protrusion 90) is unstable in a radial position between adjacent anchor portions 91 and is distorted in the circumferential direction. This is because the protrusion 90 tends to contract radially inward while the resin solidifies
Data Source
AI summary
A seal structure seals between a cover which closes an opening of a case for housing a part and the case by a sealing member. The cover is provided with an annular recessed portion attached to an end of a peripheral wall forming the opening of the case and a plurality of through-holes penetrating a bottom portion of the recessed portion and spaced apart from each other in a circumferential direction. The sealing member is formed integrally with the cover. The sealing member is integrally provided with a protrusion protruding from a bottom portion over an entire circumference in the recessed portion and an anchor portion engaged with each of the through-holes to fix the sealing member to the cover. Between at least the anchor portions in the recessed portion, a projecting portion for closing the gap between the protrusion and an inner wall of the recessed portion is provided.