Brushing – scrubbing – and general cleaning – Attachments – Optical-member-attachable cleaner
Reexamination Certificate
1999-09-17
2001-07-03
Graham, Gary K. (Department: 1744)
Brushing, scrubbing, and general cleaning
Attachments
Optical-member-attachable cleaner
C015S250451, C029S897200
Reexamination Certificate
active
06253411
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a support element for a wiper strip which is a part of a wiper blade for windshields of motor vehicles, and a method for producing it.
Support elements of this type should ensure that the force with which the wiper arm connected with the support element is pressed against the windshield is distributed as uniformly as possible. Due to a corresponding curvature of the support element when not under load—that is, when the wiper blade rests against the windshield—the ends of the wiper strip which rests in its entirety against the windshield during operation of the wiper blade are loaded toward the windshield by the support element which is tensioned in this case, even though the radii of curvature of spherically curved vehicle windshields changes with every position of the wiper blade. The curvature of the support element, and therefore the curvature of the wiper blade, must accordingly be somewhat greater that the greatest curvature measured in the wiping field of the windshield to be wiped. The support element therefore replaces the complicated support clip construction with two spring rails which are arranged in the wiper strip according to practice in conventional wiper blades.
A known support element of this type (EP 0 498 802 B1) has an elongated core piece which is rectangular in cross section and made of wood, foamed material, or the like, so that the transverse forces acting on the wiper blade during the wiping operation can be absorbed without disadvantageous deformation of the wiper blade. It is relatively complicated to produce the support element and, therefore, the wiper blade because the core piece must be packed all around by nonwoven or formed fabric strips.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a support element and a method of producing the same, which eliminates the disadvantages of the prior art.
In keeping with these objects, one feature of present invention resides, briefly stated, in a support element in which the support element is produced entirely from the fiber material impregnated with the reaction mixture.
In the wiper blade according to the invention production of the support element is substantially simplified so that the wiper blade is considerably reduced in price.
The support element is well adapted to the respective requirements for the wiper blade when the support element is formed of a plurality of fiber material strips that are arranged in layers one on top of the other.
The tensile and compressive stresses occurring in the support element when it passes over spherically curved windshields are absorbed particularly well when the fiber material strips have fibers predominantly oriented in the longitudinal extension of the strips.
Transverse forces, torques and compressive stresses that occur have no effect on the wiping quality particularly when determined fiber material strips have predominantly fibers which enclose an angle of less than 90° with the longitudinal extension of the strip.
Since tensile stresses occur predominantly at the underside of the support element facing the windshield, at least the first fiber material strip layer has fibers oriented predominantly in the longitudinal extension of the strip proceeding from the underside of the support element facing the wiper strip. In certain applications, it may be advantageous when a plurality of fiber material strip layers with fibers which are oriented predominantly in the longitudinal extension of the strips are layered one upon the other at this underside of the support element.
Transverse forces, torques and compressive stresses occur repeatedly on the upper side of the support element remote of the windshield, so that layers of fiber material strip whose fibers predominantly enclose an angle of less than 90° with the longitudinal extension of the strips are advantageously arranged in the area of this upper side.
In a first embodiment form of the invention, the fiber materials strips at the underside of the support element are longer than the fiber material strips which lie on top and which decrease in length from layer to layer, so that there results a stable center part of the support element to which can be fastened a connection device for a wiper arm guiding the wiper blade. Further, this can also result in advantages for motor vehicle windshields with a particularly large curvature.
These advantages can also be achieved when the fiber material strips are broader in their longitudinal center portion than in their end portions.
A particularly economical production of the support element and, therefore, the wiper blade results according to a further embodiment form of the invention in which the fiber material strips at the underside of the support element are broader than the fiber material strips located above them which become narrower from one layer to the next. In a construction of this kind, the support element can be formed by joining endless fiber material strips of different widths. After the subsequent pressing process, the support element, which is now shaped, can be severed from the strand in a cutting station.
The requirements for the support element are met in a particularly advantageous manner when a thermosetting resin is selected as reaction mixture for impregnating the fiber material strips.
Certain fillers which change the characteristics of the support element in the desired manner can be added to this reaction mixture corresponding to the requirements demanded of the support element.
According to a process for producing a support element, a plurality of endless fiber material strips are joined, impregnated with a reaction mixture and then guided through a nozzle, wherein the multi-layered impregnated fiber material strand formed in this way is then wound with additional fiber material strips in a carousel installation and fed through another nozzle to a hot press station in which the fiber material strand is bent in its longitudinal direction and shaped in cross section, cured and then cut to the length required for the support element. A support element produced by this process can be produced in automatic installations with practically no labor costs. It is clear that costs can be further reduced in this way. Moreover, with appropriate control of the revolving speeds and/or strand forward-feed speed, the carousel installation can produce the support element in accordance with requirements, that is, for example, so that the fiber orientation at the end portions extends at a steeper inclination relative to the longitudinal axis of the support element than in the middle area of the support element.
Further advantageous developments with arrangements of the invention are indicated in the following description of an embodiment example of the support element shown in the drawing and of a production process for the support element.
REFERENCES:
patent: 3192551 (1965-07-01), Appel
patent: 3925844 (1975-12-01), Cone
patent: 4063328 (1977-12-01), Arman
patent: 525850 (1993-02-01), None
patent: 0 498 802 B1 (1993-12-01), None
Aichele Wilfried
Kiefer Martin
Kotlarski Thomas
Graham Gary K.
Robert & Bosch GmbH
Striker Michael J.
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