Variable Blade Load Cam Mechanism for Wiper Stress Reduction
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Solution Overview
Problem
Conventional windshield wiper systems with fixed blade load designs experience increased stress and friction on high-curvature windshields, leading to potential system lock-up and reduced reliability due to the inability to customize blade load as a function of wiper angle.
Innovation Solution
A wiper arm assembly with a blade load cam system that varies the blade load by using a load member, cam follower, and blade load cam to adjust the force applied to the windshield based on the wiper angle, reducing stress and friction through a customizable cam slot geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed blade load design is used in conventional windshield wiper systems, then the structure is simple and easy to manufacture, but the system experiences increased stress and friction on high-curvature windshields leading to potential lock-up and reduced reliability
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed blade load design into a dynamic, variable blade load system. The wiper arm assembly incorporates a cam mechanism with a cam slot that allows the blade load to vary continuously as the wiper arm rotates through different angles. The cam slot geometry is specifically designed to reduce blade load when the wiper arm is positioned over high-curvature regions of the windshield, preventing lock-up and reducing stress on drive components while maintaining simple overall system architecture.
2Productivity
If the blade load is increased to improve clearing performance, then the wiping effectiveness improves, but the friction and stress on components increase leading to system lock-up
Solution Approach 1:
The patent applies the local quality principle by making the blade load non-uniform across different positions of the wiper sweep cycle. The cam slot geometry is specifically designed to provide reduced blade load in local regions corresponding to high-curvature areas of the windshield, while maintaining higher blade load in regions where the windshield has lower curvature. This localized adjustment of blade load eliminates excessive friction and stress in problematic areas without sacrificing overall wiping performance.
3Adaptability or versatility
If the wiper arm rotates away from the drive mechanism on high-curvature windshields, then the wiper can access the high-curvature region, but the blade load and component stress increase
Solution Approach 1:
The patent applies the feedback principle by designing the cam slot geometry to automatically respond to the wiper arm's angular position. As the wiper arm rotates to access high-curvature regions, the cam follower travels along the cam slot, which is shaped to reduce the blade load at these specific positions. This creates a feedback mechanism where the system automatically adjusts the blade load based on the wiper arm position, reducing component stress when the arm is positioned over high-curvature regions while maintaining the ability to access these areas.
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 solution reduces system stress, torque requirements, and motor power needed, while enhancing reliability by matching blade load to the wiper angle, minimizing the risk of lock-up and improving operation on high-curvature windshields.
Implementation Method 1
The blade load cam has a cam slot. The cam slot is configured to vary the length of the load member as a function of a wiper angle
Data Source
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AI summary
A wiper arm assembly (14) has a load member (28), a wiper arm (24), and a blade load cam (32) with a cam slot (36). The load member (28) mates with a joint (40) disposed between first and second ends of the wiper arm (20). Changes in length of the load member (28) impose a force (L) in a lengthwise direction of the load member (28). The wiper arm (24) is configured to rotate relative to the blade load cam (32) about an axis proximate to the first end of the wiper arm (24). The cam slot (36) is configured to vary the length of the load member (28) as a function of a wiper angle in which the wiper angle is defined as the angle between the wiper arm (24) and a starting position of the wiper arm (24).