Polyurethane Wiper Blade Rubber for Curved-Surface Dirt Scraping
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Solution Overview
Problem
Conventional wiper blades face challenges in achieving both excellent followability to variously shaped surfaces and effective wiping performance, particularly in scraping off particulate dirt, due to issues with contact uniformity and stability, especially on curved surfaces and in harsh environments.
Innovation Solution
A blade rubber composed of polyurethane with specific storage elastic moduli ranges (E′(1) 12.0 to 18.0 MPa at 1×10−3 Hz and E′(2) 530 to 1500 MPa at 1×104 Hz, optimized for both low-frequency contact stability and high-frequency dirt scraping, is used in the wiper blade, along with a configuration that includes a tapered lip portion and a polyurethane elastomer to enhance followability and wiping performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rubber materials are used for wiper blades, then the blade can maintain contact with the surface, but the wiping performance and ability to scrape off dirt is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the storage elastic modulus of polyurethane at two different vibration frequencies. The low-frequency modulus (E′(1)) is controlled at 12.0 to 18.0 MPa for stable contact, while the high-frequency modulus (E′(2)) is controlled at 530 to 1500 MPa for effective dirt scraping. This dual-parameter control resolves the contradiction between maintaining contact and scraping dirt.
2Shape
If the wiper blade is made softer to improve followability to curved surfaces, then contact uniformity improves, but the ability to scrape off dirt deteriorates
Solution Approach 1:
The patent applies dynamics by utilizing the frequency-dependent viscoelastic properties of polyurethane. The material dynamically adjusts its stiffness based on the frequency of deformation: at low frequencies (contact phase), it remains soft for followability, while at high frequencies (scraping phase), it becomes stiff for dirt removal. This dynamic property resolution allows the blade to exhibit both soft and hard characteristics as needed.
Solution Approach 2:
The patent controls the storage elastic modulus at two distinct vibration frequencies to achieve both followability and wiping performance. By setting E′(1) at 12.0 to 18.0 MPa (low frequency) for curved surface adaptation and E′(2) at 530 to 1500 MPa (high frequency) for dirt scraping, the material parameters are optimized to resolve the contradiction between softness for followability and hardness for wiping effectiveness.
3Reliability
If the wiper blade is made harder to improve dirt scraping ability, then wiping performance improves, but followability to curved surfaces deteriorates
Solution Approach 1:
The patent utilizes the dynamic viscoelastic behavior of polyurethane to resolve this contradiction. The material's effective stiffness is not fixed but varies with the frequency of applied deformation. During low-frequency contact with curved surfaces, the material behaves softly for followability, while during high-frequency scraping actions, it behaves hard for effective dirt removal.
Solution Approach 2:
The patent resolves this contradiction by controlling the storage elastic modulus at two different vibration frequencies. The low-frequency modulus E′(1) is maintained at 12.0 to 18.0 MPa for curved surface followability, while the high-frequency modulus E′(2) is maintained at 530 to 1500 MPa for dirt scraping performance, allowing the material to exhibit context-dependent mechanical properties.
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 solution provides a wiper blade with improved followability to curved surfaces and enhanced ability to scrape off dirt without slipping, maintaining stable contact and effective cleaning performance even on complex shapes and in challenging conditions.
Implementation Method 1
in environment of a temperature of 8° C., when it is assumed that E′(1) represents a storage elastic modulus at a vibration frequency of 1×10−3 Hz and E′(2) represents a storage elastic modulus at a vibration frequency of 1×104 Hz, of the blade rubber, E′(1) is 12.0 to 18.0 MPa, and E′(2) is 530 to 1500 MPa
Data Source
AI summary
This blade rubber has a high level of an ability to follow various shapes of surfaces to be wiped and excellent wiping performance. In a blade rubber that is made of an elastic member containing polyurethane and cleans the surface of a member to be cleaned by bringing a part of the elastic member into contact with the surface of the member to be cleaned, when the storage elastic modulus of the blade rubber at a vibration frequency of 1×10−3 Hz in an environment of 8° C. is E′(1), and the storage elastic modulus at a vibration frequency of 1×104 Hz is E′(2), E′(1) is 12.0 to 18.0 MPa, and E′(2) is 530 to 1500 MPa.