Windshield Wiper Drive Shaft Speed Control for Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing windshield wiper devices often produce annoying noise due to the springing back of the wiper arm after turning positions, caused by the abrupt braking of the wiper blade against the windshield, which is intensified by the speed of the wiper arm's movement.
Innovation Solution
The method involves varying the absolute speed of the drive shaft within a specific period after each turning position, with a first absolute speed being lower than a second absolute speed, reducing the intensity of the springing back and thus the noise, by adjusting the speed profile to differ by at least 20% of the turning position time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wiper arm moves quickly in the direction of the window after turning positions, then the wiping efficiency is improved, but the noise intensity increases due to abrupt braking and springing back
Solution Approach 1:
The patent applies dynamics by making the wiper drive system's speed variable rather than constant. The control unit dynamically adjusts the rotational speed of the drive shaft based on the wiper arm's position, specifically reducing speed during the springing back phase after turning positions. This dynamic speed adjustment allows the system to maintain high wiping efficiency during normal operation while reducing noise during critical phases.
Solution Approach 2:
The patent changes the speed parameter of the drive shaft throughout the wiping cycle. By monitoring the angular position of the wiper arm and adjusting the drive shaft's rotational speed accordingly, the system optimizes the balance between wiping performance and noise reduction. The speed parameter is increased during effective wiping phases and reduced during turning and springing back phases.
2Reliability
If the wiper blade is pressed tightly against the window, then the cleaning effectiveness is improved, but the impact force against the pane increases causing more noise
Solution Approach 1:
The patent dynamically adjusts the pressing force by controlling the wiper arm's speed and acceleration. During normal wiping phases, the system maintains sufficient pressure for effective cleaning. During turning positions and springing back phases, the reduced speed naturally decreases the impact force, preventing excessive noise while maintaining cleaning effectiveness when needed.
Solution Approach 2:
The control unit performs preliminary action by detecting the approaching turning position and reducing the drive shaft speed in advance. This preemptive speed reduction prevents the wiper blade from gaining excessive momentum before impact, thereby reducing the impact force and noise during turning and springing back while maintaining normal pressure during effective wiping phases.
3Force
If the spring element pushes the wiper arm strongly in the direction of the window, then the wiper blade maintains contact with the window, but the braking creates stronger impact and noise
Solution Approach 1:
The patent applies dynamics by making the contact force variable through speed control. The spring element's effect is modulated by the drive shaft's rotational speed - during normal operation, the spring maintains adequate contact force for cleaning, while during turning and springing back phases, the reduced speed limits the impact force despite the spring's presence, thereby reducing noise.
Solution Approach 2:
The patent maintains continuous useful action by ensuring the wiper blade remains in contact with the window throughout the cycle through the spring element, while simultaneously reducing noise by controlling the speed during phases where the spring's restoring force would otherwise create impact. The continuous contact is preserved for cleaning effectiveness while impact is minimized through timing-based speed control.
Data Source
Figure 1
Figure 2
AI summary
The method involves moving a wiper blade (2) of a windscreen wiper device (1) between two turning positions with respect to a disk (7) e.g. front window, by a wiper motor that is connected with a wiper arm over a drive shaft. An absolute rotational speed of the drive shaft is selected corresponding to an absolute rotational speed at a time point lying around a determined time period after the turning positions such that the speed of the shaft is different from another absolute rotational speed at another time point lying around the determined time period before the winding positions. An independent claim is also included for a windscreen wiper device.