Wiper Blade Connecting Device Adapter Stiffness and Friction
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Solution Overview
Problem
Existing connecting devices for wiper blades to wiper arms suffer from high frictional losses and reduced stiffness, leading to potential support loss during impact or blockage, and are prone to damage from improper installation due to the use of transverse walls and lateral spring tongues.
Innovation Solution
The connecting device features outwardly facing walls with a minimum thickness of 2 millimeters, blind holes with highly polished radial and axial sliding surfaces as the sole contact points, eliminating transverse walls and lateral spring tongues, and utilizing recesses and stiffening ribs to maintain flexibility and rigidity, along with a spring tongue design that enhances stability and secure mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If transverse walls and lateral spring tongues are used to guide the adapter, then lateral guidance is provided, but frictional losses increase and stiffness decreases
Solution Approach 1:
The patent removes the transverse walls and lateral spring tongues from the adapter design. Instead, lateral guidance is achieved through the interaction between the guide rails on the joining element and the detent lugs on the adapter, eliminating the harmful frictional contact surfaces while maintaining guidance functionality.
Solution Approach 2:
The patent introduces detent lugs as intermediary elements that engage with guide rails to provide lateral guidance. This mediator mechanism replaces the direct contact between adapter walls and joining element, reducing frictional losses while maintaining guidance.
2Ease of manufacture
If thin walls are used in the adapter, then manufacturing is easier and material usage is reduced, but stiffness and support during impact decrease
Solution Approach 1:
The patent applies different wall thicknesses to different regions of the adapter. The outwardly facing walls (front end wall, rear end wall, side walls, top wall) have a minimum thickness of 2 millimeters to provide stiffness and support during impact, while internal structures may have different thickness requirements for manufacturing ease.
3Loss of energy
If hubs are enlarged to reduce friction, then bearing surfaces improve, but adapter flexibility is reduced
Solution Approach 1:
The patent segments the hub structure into blind holes with polished sliding surfaces for low-friction rotation, while the surrounding adapter material maintains flexibility. The hubs are formed as blind holes with cylindrical surfaces that form radial sliding surfaces and end faces that form axial sliding surfaces, separating the friction-reduction function from the flexibility function.
Solution Approach 2:
The patent changes the surface parameter of the hub sliding surfaces by highly polishing them to achieve low friction, while maintaining the overall hub dimensions and adapter structure to preserve flexibility. The arithmetic mean roughness is reduced to minimize frictional losses.
4Strength
If stiffening ribs are added to increase rigidity, then adapter stiffness improves, but flexibility in the hub region is reduced
Solution Approach 1:
The patent places stiffening ribs in specific recesses on the outwardly facing walls of the adapter, creating local stiffness where needed while maintaining flexibility in the hub region. The stiffening ribs are disposed in recesses and are approximately flush with the outside of the side wall adjoining the recess, providing stiffness without interfering with hub flexibility.
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 design achieves low bearing friction, precise guidance, and increased stiffness, ensuring reliable support and lateral guidance during impacts, while reducing the risk of damage and improving mounting stability, resulting in a more robust and efficient connection.
Implementation Method 1
the cylindrical surfaces of which form radial sliding surfaces and the end faces of which form axial sliding surfaces, which are highly polished with an arithmetic mean roughness of Ra
Data Source
AI summary
The invention relates to a connecting device which has a connecting element (18) of flat beam design fixed to a wiper blade (10) and an adapter (16) joined to said connecting element in an articulated manner, and also a joining element (14) that is joined to a wiper arm (12) and into the u-shaped cross-sectional profile of which the adapter (16) is inserted and, by means of a spring tongue (64) arranged on the top wall (42) thereof, is fixed to a pushbutton (66), the connecting element (18) having a central web (28) running in the longitudinal direction of the wiper blade (10) and bearing a hinge shaft (30) projecting on the long sides thereof, which is mounted in laterally flexible hubs (46) in side walls (40) of the adapter (16). According to the invention, the outwardly facing walls of the adapter (16), namely the side walls (40), the top wall (42), and the end walls (36, 62), have a general wall thickness of at least two millimeters, and the hubs (46) are to be formed as blind holes, the cylindrical surfaces of which form radial sliding surfaces (48) and the end faces of which form axial sliding surfaces (50), which are highly polished with an arithmetic mean roughness of Ra<0.2μ, and that the sliding surfaces (48, 50) be the sole contact surfaces between the connecting element (18) and the adapter (16).