Wiper Blade Force Control via Auxiliary Spring Compensation
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Solution Overview
Problem
Modern vehicle windscreen and rear window designs with aerodynamic, domed, or curved profiles cause varying angles of elevation for wiper blades, leading to inconsistent pressing forces on the glass surface, affecting contact quality and longevity due to the variable tension of return springs, which existing technologies fail to address independently of vehicle speed.
Innovation Solution
A device with a plunger acting on an auxiliary compression spring, housed alongside the main return spring, compensates for angle variations by opposing the tensile force of the main spring, maintaining a constant resultant force on the squeegee lip, using a cam profiled surface and a rotating part to manage forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single return spring is used to apply force to the squeegee, then the squeegee can be lifted and applied to the glazed surface, but the pressing force varies with the angle of elevation on curved surfaces
Solution Approach 1:
The single return spring is segmented into two separate springs: a main return spring for lifting and applying the squeegee, and an auxiliary compression spring for compensating angle variations. This segmentation allows each spring to perform its specific function independently, resolving the contradiction between ease of operation and force consistency.
Solution Approach 2:
The auxiliary compression spring changes its compression parameter based on the angle of elevation, automatically compensating for angle variations. As the angle changes during movement on curved surfaces, the compression spring's force parameter adjusts to maintain constant pressing force on the squeegee.
2Adaptability or versatility
If the angle of elevation varies on domed or curved windscreen profiles, then the wiper blade can adapt to the surface shape, but the pressing force becomes inconsistent affecting contact quality
Solution Approach 1:
The auxiliary compression spring acts as a passive feedback mechanism that automatically responds to angle changes. As the angle of elevation varies during movement on curved surfaces, the compression spring's compression state changes accordingly, providing continuous feedback compensation to maintain constant pressing force and reliable contact quality.
3Duration of action of moving object
If the return spring tension varies with angle of elevation, then the squeegee can move with the blade, but the pressing force becomes excessive or insufficient affecting effectiveness
Solution Approach 1:
The auxiliary compression spring acts as a counterweight force that opposes the variable tension of the main return spring. By providing an opposing compressive force that varies with angle, it compensates for excessive or insufficient pressing force, ensuring optimal sweeping effectiveness throughout the movement cycle.
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
The solution ensures a substantially constant pressing force on the glass surface regardless of the wiper blade's angle of elevation, improving contact quality and reducing wear on the squeegee, without requiring additional energy sources beyond the wiper's drive mechanism.
Implementation Method 1
a plunger acting on an auxiliary spring, working in compression, housed in the housing with the main return spring
Implementation Method 2
the compressive force of the auxiliary spring opposes the tensile force exerted by the main spring by maintaining substantially constant the resultant of these two forces
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
The device has a carrier (4) with a transversal axle (5) on which a case is articulated, where the case offers a support of a flexible squeegee. The squeegee is provided with a flat lip supporting on a glass surface to be wiped. A main return spring (15) is housed in the case and is worked in traction. The carrier has a push button (19) acting on an auxiliary spring (21), which works in traction so that the compression force of the spring (21) is opposed to the traction force exerted by the spring (15) by constantly maintaining the support force of the squeegee on the glass surface.