Wiper Arm Integral Alignment Key Vibration Retention
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Solution Overview
Problem
Existing wiper arm alignment keys, particularly those with a press fit design, tend to fall out due to vibrations during operation or maintenance, leading to misalignment issues.
Innovation Solution
An integral alignment key with tapered sidewalls and a notched end is designed to be press-fit into the wiper arm and drive shaft slots, preventing axial movement and accidental removal, while allowing for selective removal during service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a press fit alignment key is used to align the wiper arm head with the drive shaft, then alignment precision is improved, but the key tends to fall out due to vibration during operation or maintenance
Solution Approach 1:
The alignment key is segmented into two functional zones: an expanded upper portion that engages with the slot in the wiper arm head, and a narrower lower portion that fits into the slot in the drive shaft. This segmentation allows the key to be retained securely at both ends without requiring excessive interference fit, thereby preventing accidental dislodgment while maintaining alignment precision.
Solution Approach 2:
The alignment key transitions from a simple cylindrical press-fit design to a multi-dimensional structure with varying cross-sectional areas along its length. The expanded upper portion provides additional engagement surface area in the vertical dimension, increasing retention reliability without compromising the horizontal alignment function.
2Reliability
If the alignment key is press fit into both the wiper arm head and drive shaft slots, then the key is securely retained, but the key cannot be selectively removed for service
Solution Approach 1:
The alignment key design creates a dynamic retention system where the expanded upper portion provides strong engagement during normal operation, but the narrower lower portion allows for controlled removal when needed. The differential dimensions create a retention gradient that is strong during use but permits service removal.
Solution Approach 2:
Different portions of the alignment key have different dimensional properties: the upper portion is expanded for secure retention in the wiper arm head, while the lower portion is narrower for easier removal from the drive shaft slot. This local differentiation of qualities enables both secure operation and serviceability.
3Device complexity
If a simple cylindrical alignment key is used, then the device complexity is reduced, but the key cannot prevent axial movement or accidental removal
Solution Approach 1:
The alignment key employs asymmetric geometry with an expanded upper portion and a narrower lower portion. This asymmetric design is simple yet effective in preventing axial movement and accidental removal, as the expanded portion engages the wiper arm head slot while the narrower portion fits the drive shaft slot, creating mechanical interference that blocks axial displacement.
Data Source
AI summary
A wiper arm for supporting a wiper blade includes a wiper arm head comprises a recessed splined cup portion having a plurality of angularly adjacent teeth about the internal circumference of the cup portion wherein the cup portion includes a slot. A complementary drive shaft includes a splined head having teeth for mating engagement with the teeth in the wiper arm head. In order to facilitate the alignment therebetween, an integral alignment key is received in the axially aligned slots. The alignment key further includes a lower notched end which abuts against a bottom radial lip of the splined head to prevent the key from moving axially in the slots. As such, the key and the splined head include complementary formations preventing the key from accidentally falling out of the slots.