Wiper Arm Spring Attachment Form-Fitting Design
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Solution Overview
Problem
Longer wiper blades increase spring forces, causing the spring suspension to bend and reduce the tensile stress, which in turn decreases the contact force of the wiper blade on the vehicle window, compromising wiping performance.
Innovation Solution
A form-fitting attachment of the spring attachment to a sheet metal attachment part, where the spring hanger is slid into a receiving opening in the sheet metal fastener, ensuring the spring attachment does not bend open under high tensile stresses, and the sheet metal fastening part and spring suspension are designed as a one-piece, stamped, drawn, and bent component, optionally galvanized for corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the spring suspension is made from sheet metal, then manufacturing is simplified, but the spring attachment bends open under high tensile stresses
Solution Approach 1:
The spring attachment is segmented into multiple functional zones: a base portion integrated with the sheet metal fastening part, a receiving opening for the spring hanger, and a bent-over edge portion that forms a clamping structure. This segmentation allows each zone to perform its specific function while maintaining overall structural integrity under load.
Solution Approach 2:
The spring attachment is merged with the sheet metal fastening part to form a one-piece component produced in a progressive die. This integration eliminates separate manufacturing steps and assembly operations, simplifying production while maintaining sufficient strength through optimized geometry and material flow during forming.
2Productivity
If the spring attachment is integrated with the sheet metal fastening part, then manufacturing steps are reduced, but the spring attachment may bend under high spring forces
Solution Approach 1:
The spring attachment incorporates a receiving opening that allows dynamic adjustment and secure fitting of the spring hanger. The bent-over edge portion creates a form-fitting connection that accommodates the spring hanger while maintaining structural stability under varying spring forces during operation.
Solution Approach 2:
The design optimizes geometric parameters of the spring attachment including the shape and depth of the receiving opening, the angle and thickness of the bent-over edge, and the integration geometry with the sheet metal fastening part. These parameter optimizations ensure both manufacturability in a progressive die and sufficient reliability under high spring forces.
Data Source
Figure 1~2
Figure 3
AI summary
The arm has a sheet metal fastening part (10) comprising a spring mounting (11), which is fastened to the fastening part in a form-fit manner. The spring mounting is inserted into a retaining opening (30) that is arranged in an edge of the fastening part. The fastening part and the spring mounting are formed as a single piece, and are zinc coated. The spring mounting has an opening for a C-clamp, which is connected with a spring. A hinge is guided at the fastening part, such that a wiper blade is arranged at the wiper arm in a pivotable manner. An independent claim is also included for method for manufacturing a sheet metal fastening part of a wiper arm of a wind screen wiping device.