Wiper Blade Connection via Thermal Expansion Bonding

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Solution Overview

Problem

Existing wiper blade connection methods, such as welded connections, are costly and prone to failure under torque and vibration, especially in mass-produced products with varying weather conditions and window curvatures.

Innovation Solution

A method involving a heat treatment process to create a non-positive or positive connection between the support element and the wiper blade side part, using spaced spring rails and heat sources like hot air, thermal radiation, or induction heating to improve the bond and reduce gaps, allowing for easier assembly and enhanced durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a welded connection is used to fasten the connection device to the support element, then the connection strength is improved, but the manufacturing cost increases and production complexity increases

Engineering Contradiction:
Improveconnection strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical welding process with a thermal expansion mechanism. The support element is designed with a specific curvature that, when heated during normal operation, causes it to expand and press the connection device firmly against the support element, creating a secure mechanical bond without welding.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes temperature as a variable parameter. The support element's curvature and connection force are temperature-dependent - when heated by the engine or environment, the support element expands and increases the clamping force on the connection device, automatically adjusting the connection strength based on operating conditions.

Inventive Principle:
Principle #35Parameter changes

2Strength

If a welded connection is used to fasten the connection device to the support element, then the connection strength is improved, but the manufacturing complexity and quality control requirements increase

Engineering Contradiction:
Improveconnection strengthVSAvoidprocess control complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent replaces the complex welding process with a simple thermal expansion mechanism. Instead of requiring precise welding parameters, electrode positioning, and post-weld inspection, the design uses the natural thermal expansion of the support element to create and maintain the connection, dramatically simplifying the manufacturing process and quality control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The support element serves dual functions: it provides structural support and automatically creates the connection through its own thermal expansion. The system uses its operating temperature to self-adjust and maintain the connection force, eliminating the need for external control systems or complex assembly procedures.

Inventive Principle:
Principle #25Self-service

3Manufacturing precision

If the support element curvature is increased to accommodate varying window curvatures, then the wiper blade contact pressure distribution is improved, but the connection area between the support element and connection device decreases

Engineering Contradiction:
Improvecontact pressure distributionVSAvoidconnection area
Core Design Contradiction:
Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent uses temperature as a dynamic parameter to compensate for the reduced connection area. When the support element is heated during operation, it expands in all dimensions, increasing the contact area and clamping force on the connection device. This thermal expansion ensures that even with a smaller initial connection area due to increased curvature, the operational connection strength is sufficient.

Inventive Principle:
Principle #35Parameter changes

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 method significantly reduces production costs and improves the connection's durability by ensuring a strong, even bond that withstands changing torques and vibrations, making it suitable for mass-produced wiper blades.

Implementation Method 1

a heat treatment is then started which is directed to the support element and/or to the wiper blade side part

Methodology Applied
Scientific EffectHeat treatment: Heating

Implementation Method 2

The heat treatment ensures that the elements of the support element and the part on the wiper blade side rest closely against one another

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

The heat can be introduced particularly easily if it is directed in the form of blown hot air onto the areas that are to be heated

Methodology Applied
Scientific EffectConvection heating: Convection

Implementation Method 4

If it is necessary to bring in the heat without any other influences, the heat treatment can take place in the form of thermal radiation

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 5

it is also possible, for example, to inductively heat the support element, if it is made of metal, and thus conduct the heat in a targeted manner from the inside to the outside in a defined area

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Implementation Method 6

The heated parts are preferably shaped after the heat treatment, in particular pressed onto one another. This reduces the gaps and results in a non-positive and/or positive connection

Methodology Applied
Scientific EffectThermal compression bonding: Compression

Data Source

PatentEP2678198B1Method for producing wiper blades and wiper blade for wiping panes
Publication Date: 2020.08.19 ROBERT BOSCH GMBH
  • EP2678198B1 patent drawingFigure 1
  • EP2678198B1 patent drawingFigure 2~3
  • EP2678198B1 patent drawingFigure 4

AI summary

The invention relates to a method for producing a wiper blades and to a wiper blade for wiping panes, in particular motor vehicle panes, comprising a support element (12) for receiving a wiper strip (14), to which a connecting device (20) is attached, which has a wiper blade-side part (15) having claw-like shoulders (50) surrounding the support element (12) at least in some regions. According to the invention, the wiper blade-side part (15) is pushed onto the support element with an only slightly larger inner width (44) than the thickness of the support element (12) and positioned, and is heat-treated after positioning.