Wiper Driving Apparatus Clutch Eccentric Worm Wheel
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Solution Overview
Problem
Conventional windscreen wiper drive devices suffer from damage and abnormal operation due to repetitive on-off state changes caused by reverse rotation of the worm wheel, leading to interference and difficulty in maintaining normal power supply when the wiper arm is deformed and the driving motor malfunctions.
Innovation Solution
A wiper driving apparatus with a clutch member eccentric to the worm wheel, featuring engagement units and rotation angle limiting means that allow the clutch member to remain within the radius of rotation of protrusions even during reverse rotation, preventing damage and ensuring normal operation by selectively turning the power supply on or off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the park switch is directly installed on the worm wheel to control power supply, then the power supply control function is improved, but the park switch and driving unit are damaged due to repetitive on-off state changes when the worm wheel rotates in reverse direction
Solution Approach 1:
A clutch member is introduced as an intermediary component between the worm wheel and the park switch. The clutch member includes a clutch arm that can rotate independently and a clutch arm rotating unit that mediates the interaction between the worm wheel's protrusions and the park switch's switch flaps. This intermediary structure prevents direct transmission of reverse rotation forces to the park switch, eliminating spark generation and component damage while maintaining power supply control functionality.
2Strength
If the clutch member is separated from the worm wheel to prevent reverse rotation damage, then component durability is improved, but the clutch member cannot maintain normal track during reverse rotation leading to interference and abnormal operation
Solution Approach 1:
The clutch member is designed with dynamic characteristics that allow it to adapt to both normal and reverse rotation conditions. The clutch arm can rotate freely in both directions, and the engagement between the clutch member and worm wheel is designed to maintain proper tracking during normal operation while allowing controlled disengagement during reverse rotation. This dynamic design ensures the clutch member remains within the radius of rotation of protrusions even during reverse rotation, preventing interference while maintaining operational reliability.
3Productivity
If the protrusion contacts the switch flap to turn off power supply, then the auto-stop function is improved, but the switch flap rotates causing the clutch member to deviate from normal track during reverse rotation
Solution Approach 1:
The switch flaps are designed with asymmetric engagement characteristics. The first switch flap is engaged by the first protrusion during normal rotation to turn off power supply, while the second switch flap is positioned to be engaged by the second protrusion during reverse rotation. This asymmetric design ensures that during reverse rotation, the second protrusion engages the second switch flap instead of allowing the first protrusion to rotate the first switch flap, thereby preventing the clutch member from deviating from its normal track while maintaining the auto-stop function.
Data Source
AI summary
Provided is a wiper driving apparatus for an automobile. The wiper driving apparatus includes: a housing; a driving motor; a worm wheel installed in the housing to be rotated by the driving motor, connected to a wiper arm, and having protrusions formed on a surface thereof; and a clutch member eccentric with respect to the center of the worm wheel to be rotatably installed in the housing such that power supply to the driving motor is selectively turned on or off according to the position of the rotating clutch member relative to the housing, wherein the clutch member has an engagement unit which is caught by the protrusions of the worm wheel when the worm wheel is rotated in a first direction, and is not caught by the protrusions of the worm wheel when the worm wheel is rotated in a second direction. Accordingly, the wiper driving apparatus enables the clutch member to be disposed within the radius of rotation of protrusions without deviating from its normal track although the protrusions are rotated in a reverse direction.