In wiper blades that are, instead of the so-called stirrup system (DE 1 505 397), provided with an elongated belt-shaped, flexible spring support element for the purposes of distributing a force originating from the wiper arm so as to properly press the wiper strip against the windshield to be wiped, the unloaded support element must exhibit a specific natural curvature that is greater than the largest curvature in the wipe field of the windshield to be wiped. When the wiper blade is pressed against the windshield, it first touches the vehicle windshield (20) at the two ends 10′ of its wiper strip only (FIG. 1). Under the effect of a force originating from the wiper arm, the entire length of the wiper strip is then pressed against the windshield, wherein the support element is placed under tension. This tension must exist along the entire wipe field passed over by the wiper blade—within certain limits—, even if the radii of curvature of spherically curved vehicle windshields change at each position of the wiper blade.
If a known wiper blade of the type identified in the preamble of claim 1 of DE 100 26 419.0 is moved along the uneven spherically curved windshield and the wiper blade is deformed from an operating position that approaches its outstretched position—near the center of the windshield to be wiped—to its maximum curved operating position—near the edges of the windshield—under the pressure of the support element or due to the surface of the windshield, a relative motion results in the longitudinal direction between the belt surface of the support element and the surface of the wind deflection strip pressed against it, leading to tensions in the wiper blade. These tensions can negatively impact the wipe results and moreover can result in undesirable squeaking noises during wiper operation due to the generation of a braking effect at the flexible rails that disrupts this relative motion, caused by the friction of the material needed to make up the wind deflection strip, which is unfavorable with respect to the flexible rails. Since these undesirable effects also can occur between the wiper strip and the support element and can only be eliminated or lessened through suitable measures, the friction between the support element and the wind deflection strip increases the disadvantages illustrated.
In the wiper blade according to the invention, contact between the wind deflection strip and the support element can be prevented or at least greatly reduced, since the wind deflection strip is not connected to the support element, but is connected directly to the wiper strip and held there.
If the support element of the wiper blade has two flexible rails spaced apart from one another, an invisible, integrated connection between the two components results—wiper strip and wind deflection strip—by the fact that these components are connected to one another via the longitudinal slot remaining between the flexible rails.
This can be accomplished cost-effectively by extending one of the two components that has a stem-like continuation along the longitudinal slot to the belt surface of the support element that is opposite to it, and furthermore since the connection of the two components with one another is realized at the continuation.
In order to ensure a stabile connection between the two components when operating of the wiper blade, and one that is able to handle any high loads that may occur, it is useful if the continuation of one component has a profile shape as seen in cross section, with which a mating profile shape of the other component is associated that is matched with the first, as seen in cross section.
According to an advantageous development of the invention, the stem-like continuation is placed at a wall of the wiper strip that faces the flexible rails, wherein the continuation widens into a belt shape after penetrating the longitudinal slot, forming longitudinal holding slots for the flexible rail, and covers the inner strip edges of the flexible rails that face one another.
For manufacturing reasons, it has been shown to be advantageous if the belt-like broadening of the continuation is designed to be a positive profile shapes to which a negative profile shape is snugly matched at the wind deflection strip, said negative profile shape being designed as a notched recess, and moreover if the notched recess is designed at a wall of the wind deflection strip that faces the flexible rails.
In certain applications it can be useful if the continuation is placed at a wall of the wind deflection strip that faces the flexible rails, wherein the continuation broadens into a belt after it penetrates the longitudinal slot and reaches under the inner strip edges of the flexible rails that face one another, the belt-like broadening of the wind deflection strip continuation then contributing to the securing of the wiper strip to the support element.
Advantages result with respect to a stabile connection between the wiper strip and the wind deflection strip if for one thing the belt-like broadening of the continuation creates a positive profile shape with which a negative profile shape fashioned as a notched recess is associated that is matched with the wiper strip, and furthermore if the notched recess is designed at a wall of the wiper strip that faces the flexible rails.
In a further development of the invention, a separate, third bar-shaped component is provided to connect the wiper strip to the wind deflection strip, said component being provided with a longitudinal notch at each of two longitudinal sides opposite one another, said notches lying in a common plane for the purposes of holding the inner strip edges of the flexible rails that face one another. Between these notches remains a stem whose width is matched with the slot width. The width of the longitudinal notches is matched to the thickness of the flexible rails. The two other longitudinal sides of the bar-shaped component form positive profile shapes with which negative profile shapes associate that fit both into the wiper strip as well as into the wind deflection strip. This third component is connected first to either the wiper strip or to the wind deflection strip, thereby becoming part of this component, which is then connected to the other component. The advantage of this further development can be seen in that each of these components can be manufactured without having to compromise on the material that is suited optimally for meeting the requirements placed on each component. In particular, the material to be used for the third bar-shaped component can constitute an especially good slip partner to the material of the flexible rails of the support element.
In a continuation of the conceptual idea of the invention, the external strip edges, which face away from one another, of the two flexible rails of the support element protrude at least part of the way out from the longitudinal notches that hold them, wherein an air gap remains between the flexible rails and the wall of the wind deflection strip that directly faces it. This configuration of the wiper blade permits the complete elimination of any contact between the support element and the wind deflection strip and thus also completely eliminates the disadvantages referred to above in the fastening of the wind deflection strip to the support element.
At particularly strong loads of the wind deflection strip, for example during high vehicle speeds, it can be advantageous if the wind deflection strip is supported off of knife-edge shaped stops at the support element that are placed at its two longitudinal edges. The knife-edge shape of the support stops, only one of which must be placed at the longitudinal side of the wind deflection strip that faces away from the incident surface of the wind deflection strip if desired, minimizes the size of the surface contact and thus the negative effects already described associated with it.
An especially lightweight embodiment of the wiper blade results when the wind deflection strip has two diverging sides as seen in cross section that are connected at a common base to one another. The free ends of these sides that face the support element are supported off of the support element, via knife-edge shaped stops in particular, and supplemental positive profile shapes are placed at the two elastically deflectable sides with which negative profile shapes of the wiper strip cooperate. By eliminating one wall of the wind deflection strip facing the support element, its mass and thus the mass of the wiper blade that is to be accelerated and then braked again during each wipe stroke is reduced considerably. This allows cost savings to be made in designing the individual components of the overall wiper assembly, such as the electrical drive motor and/or the pendulum gear and the like.
To connect between the wiper strip and the wind deflection strip, a latch hook is formed in this case onto the inner wall of both of the two sides, said latch hook being directed toward the outer strip edges of the support element adjacent to it and constituting the positive profile shape. An opposite hook is associated with each of the sides that is designed at the continuation of the wiper strip and that constitutes the negative profile shape.
This is especially simple to manufacture if the opposite hooks are designed at the longitudinal walls of an existing longitudinal notch in the continuation of the wiper strip.
A variation of the lightweight design of a wind deflection strip or of a wiper blade equipped with such a wind deflection strip as illustrated above provides that the wind deflection strip has two diverging sides as seen in cross section that are connected together at a common base. The free ends of the sides of the wind deflection strip that face the support element are supported off of the wiper blade, wherein at the inner wall of one of the two sides is a positive profile shape with which a negative profile shape associates that is designed into the continuation of the wiper strip.
An only arbitrarily removable connection between the wiper strip and the wind deflection strip results if in the configuration of the invention the positive profile shape that is disc or circular in cross section is connected to one side of the wind deflection strip via a narrow longitudinal stem, and furthermore if the negative profile shape is designed as a circular longitudinal notch in cross section that at its side facing the wind deflection strip is provided with a slotted longitudinal opening matched to the thickness of the longitudinal stem.
It is useful in the process to snugly match the diameter of the positive profile shape.
A permanent, easily removable shape lock between the wiper strip and the wind deflection strip is produced by making the diameter of the positive profile shape that is made of an elastic material to be smaller than the diameter of the negative profile shape, by providing the positive profile shape with a longitudinal hole and by providing a bar that is introduced into this longitudinal hole and that expands the diameter of the positive profile shape to the diameter of the negative profile shape. The pre-assembly is particularly simple as a result since the diameter difference between the negative and the positive profile shape allows the two parts to simply be pushed together. A permanent shape lock is achieved by inserting the bar into the longitudinal hole, which expands the positive profile shape to the diameter of the negative profile shape. This opens up the ability to connect the two components automatically.
So as to be able to utilize the advantages of cost-effective extrusion processes in the manufacture of the wind deflection strip and the wiper strip, the cross sections of these two components are each uniform along their entire length. Regardless of this, however, the cross sections can be subsequently partially changed if this is required for the placement of a half-coupling to the wiper blade, for example, so as to be able to connect the wiper blade to a driven wiper arm.
Further, it can be advantageous if the wind deflection strip and the wiper strip are glued together at their points of connection. The expression “bonding” stands in this case also for other connection processes such as for example vulcanization, etc.
Other advantageous further developments and configurations of the invention are provided in the following description of embodiment examples as illustrated in the associated drawing.