Wiper Arm Spring Retraction via Gap Section
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Solution Overview
Problem
Conventional wiper arms with coil springs increase in thickness due to the protrusion of hook sections when the retainer rotates to its upright position, compromising mechanical strength and aesthetics.
Innovation Solution
Incorporating a gap section in the arm body and a corresponding recess in the arm head allows the spring member to retract within the wiper arm structure, eliminating the need for hook sections and reinforcing the mechanical strength with projections or bridge sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hook section is provided on the coil spring to prevent contact with the retainer or arm head when the retainer is in the upright position, then the spring member can be retained within the wiper arm structure, but the thickness of the wiper arm increases
Solution Approach 1:
The patent introduces a gap section that extends in the thickness direction of the wiper arm, creating a new dimensional space for the spring member to move into. When the retainer rotates to the upright position, the spring member moves axially into the gap section, allowing it to be retained without requiring a hook section that would protrude and increase overall thickness.
Solution Approach 2:
The bottom portion of the retainer is divided into divided pieces by the gap section, creating separate segments. This segmentation allows the spring member to be positioned within the gap created by the divided pieces, enabling retention functionality while maintaining a compact overall structure without the need for thick hook sections.
2Ease of operation
If the bottom portion of the retainer is divided into divided pieces by a gap section, then the spring member can move into the gap section to avoid contact with other parts, but the mechanical strength of the retainer decreases
Solution Approach 1:
The reinforcing section is positioned asymmetrically within the gap section, specifically on the inner circumferential surface facing the pivot shaft hole. This asymmetric reinforcement provides targeted structural support at the critical location where stress is highest, compensating for the weakness introduced by the gap section while allowing the spring member to move freely in other areas.
Solution Approach 2:
The reinforcing section provides localized strengthening only at the specific position where structural support is needed (inner circumferential surface of the gap section), rather than uniformly thickening the entire retainer. This allows the retainer to maintain adequate mechanical strength while preserving the gap section's functionality for spring member movement.
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 reduces the overall thickness of the wiper arm while maintaining sufficient mechanical strength, as the spring member is fully housed within the arm body and arm head, and the reinforcing sections prevent deformation of divided pieces.
Implementation Method 1
a coil spring 4 interposed between the arm head 2 and the retainer 3
Data Source
Figure 1
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AI summary
There is provided a wiper arm rotatably connecting an arm body to an arm head and including a spring member provided between the arm head and the arm body, the thickness of which is decreased while its mechanical strength is sufficiently maintained. A gap section (33) reaching a pivot shaft hole (31) is provided in a head connection section (21) of a retainer (3). A recess (14A) is provided on a pivot shaft section (14) of an arm head (2). During the retainer (3) rotates, a straight section of the coil spring (4) moves from the gap section (33) to the recess (14A). When the retainer (3) reaches its upright position, the straight section is disposed within the recess (14A). The pivot shaft section (14) includes a projection (14B) disposed within the gap section (33) and in contact with the divided pieces (33), (35) on the both sides of the gap section (33).