Eccentric Bushing Relief Channels for Wiper Drive Assembly
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Solution Overview
Problem
The assembly of eccentric bushings in windshield wiper drive units is hindered by compressed air volumes and capillary issues that lead to counterforces and water ingress, making the process unreliable and prone to errors.
Innovation Solution
Incorporating relief channels in the bushing's flange and mounting sections to allow fluid flow and vent capillary spaces, preventing water ingress and reducing air compression, thereby facilitating safer and more robust assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the intermediate area of the eccentric bushing is designed without contact to the assembly bore, then the bushing can be mounted with proper clearance, but air volume is enclosed and compressed during assembly generating counterforce that prevents correct fitting
Solution Approach 1:
The bushing is divided into functional sections: a mounting section with pressing areas for secure installation, an intermediate area for rotational movement, and a flange section for positioning. This segmentation allows each section to perform its specific function while resolving the contradiction between maintaining clearance and enabling proper assembly.
Solution Approach 2:
The intermediate area acts as an intermediary zone between the mounting section and flange section, providing the necessary clearance for rotational movement while being controlled in its interaction with the assembly bore to prevent harmful air compression during installation.
2Stability of the object's composition
If the collar of the flange section contacts flat on the transmission housing, then the bushing is securely positioned, but capillaries are formed between them allowing water to enter the housing
Solution Approach 1:
The harmful capillary spaces between the collar and transmission housing are eliminated by modifying the contact interface design. The collar is designed to contact the housing in a way that prevents capillary formation, extracting the harmful effect from the system while maintaining secure positioning.
Solution Approach 2:
The collar interface is designed with surface characteristics that prevent capillary action, creating a contact interface that is effective against water ingress while maintaining the necessary mechanical connection and positioning stability.
3Strength
If pressing areas are designed for secure mounting, then the bushing can be firmly installed, but air compression in enclosed volumes generates counterforce that becomes too great for correct assembly
Solution Approach 1:
The mounting section is segmented into pressing areas with controlled contact to the assembly bore, ensuring firm installation while preventing complete air enclosure. This segmentation allows strong mounting without excessive air compression counterforce.
Solution Approach 2:
The geometry of the pressing areas and intermediate area is optimized to control air volume and pressure distribution during assembly, enabling strong mounting while maintaining assembly feasibility by managing the air compression parameter.
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 relief channels ensure reliable assembly by eliminating counterforces and water ingress, improving the bushing's behavior during installation and maintaining a stable environment by preventing fluid and pressure imbalances.
Implementation Method 1
the bushing (30) has a relief channel (342) in such a way that a fluid can flow through the relief channel (342) when the bushing (30) is mounted in/on a component (26, 27) and/or in a mounted state on/in the component (26, 27)
Implementation Method 2
During the assembly process, this air volume can be compressed quickly, which generates a force counter to the assembly direction of the eccentric bushing. This counterforce can become so great that the eccentric bushing can no longer be fitted correctly.
Implementation Method 3
when the eccentric bushing is installed, it is problematic that between the collar of the flange section and its flat contact on the transmission housing, water can enter the housing through capillaries formed between them
Data Source
Figure 1
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Figure 4
AI summary
The invention relates to a bushing (30) for a drive unit, in particular an eccentric bushing (30) for a wiper drive of a windshield wiper, having an axial mounting section (32) and a radial flange section protruding therefrom, wherein the bushing (30) can be mounted having the mounting section (32) and having the flange section in/on a component, wherein the bushing (30) has a relief channel (322, 342) such that a fluid can flow through the relief channel (322, 342) upon mounting of the bushing (30) in/on the component and/or in a mounted state on/in the component. The invention furthermore relates to a drive unit, in particular a wiper drive for a windshield wiper of a motor vehicle, having a bushing (30) according to the invention.