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Technical Paper

Wear Indicator for Wiper Blades

2001-03-05
2001-01-0744
For wiper systems, rubber-wiping elements are one of the key components ensuring excellent wipe quality and, therefore, satisfying driver visibility, security and comfort. In order to track the rubber element wear precisely and to know when the blades have to be changed, a wear indicator for the rubber element has been developed. The indicator is made of a black plastic material with an adhesive, pressure sensitive, backing located on the main bow. With time and external stresses, the sticker turns a green color at mid life, and yellow at the end of life. Yellow color indicates to the driver, the end of the effective life of the wiper blade.
Technical Paper

A Novel Use of a Composite Material to Limit the Loads in Windshield Wiper Systems

2001-03-05
2001-01-0104
Using a thermoset polyester/glass fiber pultruded composite material, and taking advantage of column post-buckling behavior, a rigid/perfectly-plastic member can be approximated. Employment of the composite material is essential to realize an appreciable reduction in length of the member, while staying within the elastic range of the material. Utilizing this member as the connecting rod of 4-bar linkages found in automotive windshield wiping systems can limit the peak system loading occurring as a result of snow/ice pack above the cowl screen. This technology holds the potential for reliability, wipe quality, and cost improvement along with mass reduction in windshield wiping systems.
Technical Paper

E-Modularization of Rear Closures: Integration of New Generation of Electrical Systems

2001-03-05
2001-01-0693
This paper presents the potential for rear closure submodules. Side door modules and lightweight rear closures have attracted a lot of attention in recent years. However the characteristics of future liftgates allow the design of specific mechatronic sub-modules (e-modulesTM). Beside structure, rear closures satisfy three main functions: rear vision, rear signaling and rear access. All are undergoing a generation change that will be outlined in the first part of this paper, system by system. Each time the rationale behind modular integration, whether electronic or mechanical, will be reviewed. The second part presents examples of e-modulesTM that illustrate the potential gains in terms of ease of assembly, packaging optimization and network integration.
Technical Paper

Acoustic Sources localization: Application to Wiper Aerodynamic Noises

2003-05-05
2003-01-1700
The reduction of aerodynamic noise sources is today an important topic in automotive industry. In order to localize the different sources on the arm and blade, a 48 microphones acoustic antenna coupled with a software based on the beam-forming imaging method has been used. Obtained results are validated inside the car on track. Aerodynamic numerical simulations are compared to aerodynamic measurements. The turbulent kinetic energy distribution obtained from the simulations is then compared with measured sound sources localization maps: the results are presented and commented for two wiper configurations.
Technical Paper

Wiper System Dynamic Behavior

1997-02-24
970588
In this paper are presented some results about the dynamic of the wiper systems, vibratory phenomena and some influences of the friction, the weight and the clearances.
Technical Paper

Windshield Wiper System mechanism modeling focused on reduces the propagated noise and vibration

2007-11-28
2007-01-2667
A resonance measurement methodology has been developed by Valeo Wiper Systems in order to determine the best frame tube configuration of a new project. The wiper system mechanism is operated by a motor that propagate noise and vibration to the system. It is known that the frequencies that causes bad sensation to the human hearing are the low frequencies, and it is necessary to determine a frame tube that decreases the vibration and do not pass these vibrations to the vehicle body. There are two ways to reduce the vibration propagated by the motor to the vehicle: broke the resonance in the frame tube with different designs or use grommets in the contact surface between the vehicle body and the wiper mechanism. The resonance analysis has been performed by using an impact hammer and accelerometers that measure the vibration propagated.
Technical Paper

Windshield Wiper System life improvement using overstress testing to determine the product weak point

2007-11-28
2007-01-2660
An overstress testing methodology has been developed by Valeo Wiper Systems and followed in order to decrease the project validation time and determine the wiper system mechanism reliability. This methodology could be followed to analyze new projects, as well as quality problems, improvements ideas and to test new materials. The stress levels were calculated by using the cumulative fatigue laws. During the accelerated test the samples were tested until some component or function fail. In order to have representative results, all the failure modes shall be compared with the FEA (Finite Element Analysis) performed with the drawings. The main objective was to verify the possibilities of reliability increasing to have a robust product, and it was necessary to validate the product weak point. The reliability level is determined by using the Life Data Analysis methodology, acquiring the number of the wiping cycles performed until the failure.
Technical Paper

Numerical Simulation of Wiper System Aerodynamic Behavior

2001-03-05
2001-01-0036
Valeo Wiper Systems (VWS) has invested in the CFD Fluent package since 1996. This paper reports the means implemented and the results obtained in 1997 during several validation campaigns for various configurations of wiper-blades placed on a flat glass. The calculation method is described, from the conversion of the CATIA CAD data to the calculation itself. Numerical results are close to experimental data, obtained from the aerodynamic scales especially built for a CFD validation purpose. The benefits due to the improvements of the CFD software Fluent and the workstations performances since 1997 are also estimated.
Technical Paper

Windshield Shape Optimization Using Neural Network

2004-03-08
2004-01-1156
Wipe quality of wiper systems is influenced not only by the definition of the wiper system, but also by the shape of the glass. In order to optimize the overall performance of the system, Valeo Wiper Systems has developed an optimization algorithm, which is based on geometrical criteria. The multi-criteria objective not only considers wipe quality but also constraints by glass feasibility and respect of optical standards. As the direct derivation of the objective functions is not available, a neural network approximation is used at the place of the real function. A neural network with several outputs enables the engineer to include his knowledge in the optimization loop by changing disciplinary weights.
Technical Paper

An Innovative Method of Heating Windshield Washer Fluid for Improved Windshield Cleaning Efficiency

2004-03-08
2004-01-0784
In vehicles today, the visibility through the windshield is decreased due to contaminants such as oils, waxes, organic matter, frost, snow, or ice that collect on the windshield surface. Ordinary washer fluid in conjunction with the wiper system is not always effective in removing these contaminants. By increasing the temperature of the washer fluid, it is possible to dramatically increase the cleaning efficiency of the windshield washer system. By using a uniquely designed, electronically controlled device, the temperature of the washer fluid applied to the windshield can be increased without damaging side-effects to the fluid, vehicle or human components. This technology will enhance the driver's ability to see through the windshield under all driving conditions.
Technical Paper

Wiper Systems With Flexible Structures - Instabilities Analysis and Correlation with a Theoretical Model

2005-05-16
2005-01-2375
Optimizing the wiper system performance motivates the design engineer to create a product as robust as possible against the occurrence of wipe defects related to vibratory phenomena between the rubber blade and the windshield. In some configurations, these vibrations generate visual or audible annoyance for the driver. These instabilities phenomena only appear under specific operating and environmental conditions characterized by windshield moisture and cleanness, contact pressure of the rubber blade on the glass, attack angle of the wiper blade on the windshield, component stiffness, windshield curvature etc. In the process of eliminating all potential instabilities, modeling the wiper system structures can contribute to understand its working dynamics. Therefore, a new computation tool is developed and validated by experimentation on a specific test bench.
Technical Paper

An Application Flexible Method to Limit the Loads in Windshield Wiping Systems

2005-04-11
2005-01-1835
Historically, a number of devices have been conceived to prevent windshield wiping systems from being damaged by restriction of the wiping pattern. Although these devices are viable, they possess limitations that may affect their applicability. In response to these limitations, a motor mounted device has been developed. This device is capable of providing load limiting in a wider variety of applications. It also possesses enhanced functionality. The operation of the device is predicated on the use of a post-buckled pultruded composite column, which serves as a preloaded compression spring. The resulting device acts akin to an elastic, rigid - perfectly plastic member that at a prescribed load level contracts the crank radius thereby allowing the system to continue running while also limiting the system loading. Ultimately, utilizing such a device has the potential to allow for greater pattern control, wipe quality, and reliability of windshield wiping systems.
Technical Paper

Simulation of Mechanical Pressure in a Rubber-Glass Contact for Wiper Systems

2002-03-04
2002-01-0798
The mechanical pressure distribution under a wiper blade is considered as an essential parameter for the generation of wiping defects. In this paper, experiments are first performed to show the heterogeneity of this parameter on a flat glass due to the structure of the wiper blade. This heterogeneity is then strengthened by the curvature of the windshield as observed in following experiments. Thanks to these results and conclusions, a mathematical model, based on elastic foundations theory, is developed here for the simulation of this parameter. The final theoretical results show good correlation with experiments on either flat glass or real windshield. From now, this model provides a numeric tool to engineering departments, for the simulation of the pressure distribution under a wiper blade in the early phases of the design of new system. The algorithm, which requires a general description of the system, can be applied to any wiper blade on any windshield and requires little CPU time.
Technical Paper

Overstress Testing to Determine the Factor of Safety of a Windshield Wiper System

2002-03-04
2002-01-1230
Overstress testing is often used in design development for quick test results of a product's weak point. More helpful would be to know how well the product would hold up to various real life conditions. In this paper, overstress testing is used to obtain design characteristic data of a windshield wiper linkage under various loading conditions. Those characteristics, such as stress levels, fracture reliability, and fatigue limit can be compiled using popular fatigue analysis theories such as Ray Projected Method and Miner's Law to calculate the factor of safety of the product for both infinite and finite design philosophies.
Technical Paper

Simulation of Chatter Vibrations for Wiper Systems

2002-03-04
2002-01-1239
An experimental investigation is first carried out to analyze the influence of the geometrical configuration of a wiper system on the chattering occurrence. The measurement results show a combined influence of the load applied on the rubber blade and the attack angle on the vibratory level of the blade. A mathematical four-degree of freedom model, based on the Sprag-slip theory, is developed to simulate the behavior of the rubber blade during the wiping motion. A dynamic analysis is then performed to define conditions for stable motion of the system. The comparison of these theoretical unstable configurations and the experimental chattering cases shows good correlation. This theoretical survey points out necessary conditions for unstable motion, in terms of orientation of the rubber blade to the glass surface.
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