Title of Invention

WIPER BLADE FOR PANES, IN PARTICULAR OF MOTOR VEHICLES, AND METHOD FOR PRODUCING SUCH A BLADE

Abstract

A wiper blade for panes, in particular for motor vehicles, having at least one support element, a wiper strip and a connecting means for a wiper arm, the support element being an elongated flat beam on which the wiper strip and the connecting means are fastened, characterized in that the support element has a cross-sectional profile in which F *r ~f -< 0.009 48 * E * I Z% where Fwf is the contact force exerted by the wiper arm on the wiper blade, or the contact force for which the wiper blade was originally designed, and L is the length of the support element, E is the modulus of elasticity of the support element, lzz is the moment of inertia of the cross-sectional profile about the z axis perpendicular to an s- axis running with the support element, and also perpendicular to a y-axis.

Full Text

Wiper blade for panes, in particular of motor vehicles, and method for producing such a blade Prior art In the case of wiper blades ' of the type designated in the preamble of Claim 1, the support element is intended to ensure on the pane, over the entire wipe pattern swept by the wiper arm, a predetermined distribution of the wiper blade contact force proceeding from the wiper arm - frequently also denoted as contact pressure. By means of a corresponding curvature of the unloaded support element - that is to say when the wiper blade does not bear against the pane - the ends of the wiper strip, which are laid fully against the pane during operation of the wiper blade, are loaded towards the pane by the then stressed support element even when the radii of curvature of spherically curved vehicle panes change with each wiper blade position. The curvature of the wiper blade must therefore be somewhat stronger than the strongest curvature measured in the wipe pattern on the pane to be wiped. The support element therefore replaces the complicated handle-like structure by two spring rails arranged in the wiper strip, as is practised with conventional wiper blades (DE-A 15 05 357). The invention proceeds from a wiper blade according to the generic concept of the independent claims. In a known wiper blade of this type (DE-C 12 47 161), for the purpose of achieving as uniform as possible a pressure loading of the wiper blade on a flat pane over its entire length, a plurality of configurations of the support element are provided as a solution to the problem. In another known wiper blade of this generic type (EP 0 528 643 Bl) , in order to achieve a uniform pressure loading of the wiper blade on spherically curved panes the pressure loading on the two end sections increases substantially when the wiper blade is pressed against a flat pane. The uniform pressure distribution, aimed at in both cases, over the entire wiper blade length has the effect, however, that the wiping lip which belongs to the wiper blade and carried” out the actual wiping work jumps over suddenly over its entire length from one dragging position to its other when the wiper blade reverses its working direction.- This dragging position is mandatory for the wiper system to operate effectively and with low noise. This sudden jumping over of the wiping lip - which is necessarily associated with an up and down movement of the wiper blade - generates undesired knocking noises, however. Again, tuning the support element stress to the desired pressure distribution, which can differ from case to case, is problematical in the case of spherically curved panes. EP 0 594 451 describes flat beam wiper blades with a variable profile which are intended not to exceed a specific lateral deflection upon the application of a test force. For this purpose, a variable which is intended not to exceed a specific limiting value is specified via an extremely complex relationship between internal parameters determining the spring beam. Statements on the variables which are actually to be used can be derived from the specified equation only with difficulty and incompletely. The further details relate to an unloaded wiper blade, and so statements on the quality of a wiper blade in operation are scarcely possible. Moreover, the conversion of the teaching of the known prior art proves to be difficult, since the parameters available cannot be applied directly to wiper blades which are to be produced from new. Advantages of the invention The wiper blade according to the invention and having the features of the main claim has the advantage of a consistently good wiping quality, because, inter alia, rattling of the wiper blade over the pane. - the so-called slip-stick effect - is avoided. This results from the finding that, in particular, the lateral deflection angle and less so the absolute lagging, that IS to say the absolute deflection of the tips under load is to be borne in mind for the slip-stick effect . It is therefore advantageous when the wiper blade is designed such that the lateral deflection of the ends of the wiper blade, which lag in operation, do [sic] not exceed a lateral deflection angle of a specific size, It is then possible to derive from the size found for these angles parameters which are important for the wiper blade which have a simple relationship to one another and are not to exceed an upper limit of 0.009 in this relationship. Cross-sectional profiles for the support element can be determined very easily with the aid of this relationship and of the specified upper limit, and then lead to a good wiping result, Wiper blades with a constant cross section along their length, especially, are particularly easy to produce in this way. Advantageous developments and refinements of the wiper blade according to the invention are possible by means of the measures specified in the further claims, The wiping quality increases further when the ratio of the product of the contact force and the square of the length to the product of 48 times the modulus of elasticity of the support element and the I’’ moment of inertia does not exceed an upper limit of 0.005. Cross-sectional profiles which can be applied particularly effectively are of rectangular shape and have a substantially constant width and a substantially constant thickness over the length of the wiper blade. The support element can in this case also comprise individual beams which are arranged laterally next to or one above another and whose total width or whose total thickness add together in each case to a total width and/or to a total thickness, In the case of such a rectangular cross-sectional profile, the moment of inertia I’. can be used as- d*bVl2, it being ., respectively necessary to 'use the total thickness or the total width for d and b. The result of this is a relationship which is very easy to manipulate and via which the support element can be optimized for the wiper blades when the specified upper limits of 0.009 and, in particular of 0.005 are not exceeded. Particularly when more complex cross-sectional profiles are selected for the support element which, for example, vary over the length of the wiper blade or have a ladder-like structure or similar, it is possible nevertheless to achieve a good wiping quality when it is considered that the lateral deflection angle y do [sic] not exceed a magnitude of 0.5°, in particular of 0.3°, during operation of the wiper blade. These data hold for a mean coefficient of friction ja of 1, and are to be correspondingly increased or decreased in the case of larger or smaller coefficients of friction. The lateral deflection angle y is the angle at which the tangent to the support element end intersects the axis running in the direction of the longitudinal extent of the support element. In a first approximation, this can also be understood as the angle enclosed by the axis in the direction of the longitudinal extent of the support element and a straight line through the point of action of the wiper arm on the support element and through a support element end. Very good wiping results can be achieved when the width b and the thickness d have a specific relationship to the total length of the support element. In particular, the product of .the width and the square of the thickness is not to exceed 4 0 times the square of the length, and not to fall below* 20 times the square of the length. The widths and/or the thicknesses of assembled support elements add together in each case to a total width or total thickness, respectively, which is then taken into account. The wiper blade according to the invention and having the features of Claim 1-0 has the advantage that only one parameter need be varied in order to adjust the contact force distribution, which drops off outwards. The curvature or the curvature profile along the support element can be preset in freely programmable bending machines. It is possible thereby also to carry out short test series for optimizing the contact force distribution and thus the curvature profile quickly and without a high outlay. In particular, it is advantageous when the coordinate governing the curvature profile runs along the inertial element. This avoids complicated recalculations to a Cartesian coordinate system in which each change in a position X causes a shift in the following "x values". The mathematical relationship between the second derivative of the curvature with respect to the adapted coordinate and the contact force profile, likewise with respect to the adapted coordinate, becomes particularly simple when the modulus of elasticity of the material of the support element, and the area moment of inertia of the support element are constant over the length thereof * For a prescribed contact force distribution, it is then possible to calculate the curvature directly by twofold integration or else numerically, An optimum adaptation of such a wiper blade even to panes with a more complicated curvature profile is possible when the curvature of the pane is subtracted from the curvature of the support element, or the second derivative of the curvature of the pane is subtracted from the second derivative of the curvature of the support element. In this case, it is possible to prescribe a contact force distribution such as is desired for a wiper blade which is pressed onto a flat pane. The difference between the second derivatives of the respective curvatures is then proportional again to this contact force distribution. A wiper blade according to the invention and having the features of Claim 15 is distinguished ivy that an excellent wiping result is -achieved without specific adaptations for average types of pane. As a result of the very simple measure set forth, the contact force distribution satisfies the requirements in the great majority of cases. The said interpolation points are satisfactorily accurate in order thereupon to determine a curvature profile to be maintained. A wiper blade according to Claim 15 is optimized by the measures of Claim 16. Even in the case of more complex pane curvature profiles, the wiping quality can be increased by prescribing the contact force distribution at specific interpolation points * It is possible, nevertheless, to design the wiper blade without complicated calculations. The curvature profile can be substantially predetermined and optimized by simple tests, An excellent wiping quality is ensured as long as the prescription are [sic] met that the contact force distribution which prevails when the wiper blade is pressed onto the pane to be wiped in a region approximately half way between the middle and end of the wiper blade is higher than at the end of the wiper blade, In a method according to the invention for producing such a wiper blade, the individual parameters are selected in accordance with the teaching according to the invention, and the support element is pre-bent such that is curvature profile fulfils at least one of the above named conditions. It is particularly favourable in this case for the support element to be bent first and then assembled with the wiper strip and the connecting element. However, it is also possible to connect the connecting element to the support element and only then to add the wiper strip. Drawing In the drawing: Figure 1 shows a perspective illustration of a wiper blade which is laid on the pane and connected to a wiper.,;: arm loaded---towards the pane; Figure 2 shows a diagram of a. side view of an unloaded wiper blade placed onto the -'‘'ane, illustrated in a reduced fashion by comparison with Figure 1; Figure 3 shows the cut surface of a section through the wiper blade in accordance with Figure 1, ‘lohg the line III-III, in an enlarged representation; Figures 4 and 5 show a variant of Figure 3; Figures 6 and 7 show a wiper blade in another embodiment, with a coordinate system drawn in; Figures 8 and 9 respectively show calculated and measured values for the contact force distribution, plotted against the length of the wiper blade; and Figure 10 shows a diagram (not to scale) of a support element belonging to the wiper blade, in side view. Description of the exemplary embodiment A wiper blade 10 illustrated in Figure 1 has an elongated, resilient support element 12, also to be denoted as a flat beam, for a wiper strip 14, which is illustrated separately in Figure 10, As may be seen from Figures 1, 3 and 4, the support element 12 and the wiper strip 14 are connected to another with their longitudinal axes parallel. Arranged on the top side of the support element 12 which is averted from the pane 15 to be wiped - drawn in Figure 1 with dots and dashes - is a connecting device 16 which acts as connecting means and with the aid of which -the wiper blade 10 can be detachably connected to a driven wiper arm 18 guided on the body of a motor vehicle. The elongated, elastomeric wiper strip 14 is arranged on the underside, facing the pane 15, of the support element 12. A hook which serves as a mating connecting means and embraces a joint bolt 22 belonging to the connecting device 16 of the wiper blade 10 is integrally formed on the free end 20 of the wiper arm 18, Locking means (not illustrated in more detail) known per se and designed as an adapter provide the lock between the wiper arm 18 and-the wiper- blade 10, The wiper arm 18, and thus also its hook end 2 0 are loaded in the direction of the arrow 24 relative to the pane 15 to be wiped, whose surface to be wiped is indicated in Figures 1 and 2 by a dashed and dotted line 26. The contact force F’’ (arrow 24) lays the wiper blade 10 over its entire length against the surface 2 6 of the pane 15 to be wiped. Since the line 26 illustrated by dots and dashes in Figure 2 is to represent the strongest curvature of the pane surface in the region of - the wipe pattern, it may clearly be seen that the curvature of the as yet unloaded wiper blade 10 bearing with its two ends against the pane is stronger that the maximum curvature of the spherically curved pane 15. Under the action of the contact force F’’ (arrow 24) , the wiper blade 10 is laid over its entire length with its wiping lip 28 belonging to the wiper strip 14 against the pane surface 26, In this case, a stress which ensures that the wiper strip 14 and the wiping lip 28 bear properly against the motor vehicle pane 15 over their entire length is built up in the strip-like resilient support element 12. During wiping operation, the wiper arm 18 moves the wiper blade 10 transverse to its longitudinal extent over the pane 15, This wiping or working movement is denoted in Figure 1 by the double arrow 29. The aim below is now to look more closely at the particular configuration of. the wiper blade according to the invention* As shown in Figure 3, which is not to scale, the wiper strip 14 is arranged on the lower strip face, facing the pane 15, of the support element 12, At a spacing from the support element 12, the wiper strip 14 is constricted starting from both its longitudinal sides such that a swiveling web 30 remains in its longitudinal middle region and extends over the entire length of the wiper strip 14. The swivelling web 3 0 merges into the wiping lip 28, which has a substantially wedge-shaped cross section. The contact force (arrow 24) presses the wiper blade or the wiping lip 28’ ag.3.inst' the surface 26, to be wiped, of the pane 15, the wiping lip being swivelled nudes’ the influence of the wiped’ movement - of which one of the two oppositely directed wiping movements (double arrow 29) is specifically considered in Figure 3 and is indicated by the directional arrow 32 - into a so-called dragging position in which the wiping lip is supported over its entire length on the part of the wiper strip 14 held on the support element 12, This support, which is marked in Figure 3 by the arrow 34, is always performed - as a function of the respective wiping direction (double arrow 29, arrow 32 respectively) on the top edge, trailing in the respective wiping direction, of the wiping lip 28, such that the latter is always guided over the pane in a so-called dragging position. This dragging position is necessary for effective and low-noise operation of the wiper device. The reversal of the dragging position is performed in the so-called reversing position of the wiper blade 10, when the latter reverses its wiping movement (double arrow 29). In this process, the wiper blade executes an up and down movement which is caused by the swivelling over of the wiping lip 28. The upward movement is performed against the direction of the arrow 24, and thus also against the contact force. The result in the case of the other wiping movement, directed against the arrow 32, is therefore a mirror image of Figure 3, Figure 4, which is illustrated enlarged by comparison with the wiper blade in Figure 1, shows a cross-sectional profile 40 having a rectangular cut surface with a width b and a thickness d. A coordinate system is also drawn above the support element 12. An s-coordinate following the curvature of the support element 12 and to which the y- and 2-coordinates are perpendicular, is drawn in as third coordinate in Figure 6 - If the wiper blade 10 is now pressed with a force F„f (arrow 24), in particular by .-the wiper arm 18, onto a pane 26, the result is a certain force distribution p(s) which leads to a moment M(s) which is at a maximum in the middle of the support element 12. For a constant contact force distribution For a outwardly decreasing contact force distribution, which is suitable, in particular, for swivelling the wiping lips, moment M(s) is somewhat smaller over its entire length than the moment calculated for a constant force distribution: If it is now assumed that .the coefficient of friction |i is approximately 1 for a dry pane, the lateral moment is equal to the bending moment M(s) during operation, and this follows, in particular, from the prescribed force distribution p(s) * A lateral deflecting angle y, which can be calculated by integrating the individual deflections from the point of action of the wiper arm on the wiper blade : up,..,..to the wiper blade end, follows from the’ lateral bending moment. In the case of --a connecting device 16 arranged in the middle, the deflection angle is calculated in accordance with Taking account of the relationship of the moment for a constant contact force distribution, the following simple estimate is obtained for the angle y: The invention is based, inter alia, on the finding that good wiping quality is achieved, particularly by avoiding rattling, when the angle y does not exceed the magnitude 0,5° (= 0.009 red) , in particular the magnitude 0,3° (= 0.005 rad). It is thereby possible to derive a simple relationship between the contact force and the geometrical variables of the wiper blade, in accordance with which . As illustrated in Figure 3, for the most frequently occurring case of a rectangular profile 40, the moment of inertia is determined as: Iz2 = d*b’ 12 where d = thickness of the support element, and b = width of the support element. The width b and the thickness d are therefore to be selected such that ‘‘ 4*E*d*b'‘ in particular If the support element 12 is split up into two individual spring beams 42 and 44, as is illustrated in Figure 4, given the above considerations it is possible to assume in the first approximation that the width b is the sum of the individual widths bl and b2; b=bi+b2 * It is thereby possible for simple relationships between the width and thickness of a support element to be derived even for such systems. In the event that no rectangular cross-sectional profile is to be selected, it is necessary to determine the moment of inertia I’’ and substitute it correspondingly into the above named relationships. Likewise, appropriate account should be taken in the above considerations of cross-sectional variations over the length of the wiper blade, or of a- non-central point of action of the wiper arm on the wiper blade. In order to swivel the wiping lip 2 8 over from its one dragging position into the other with as little noise as possible, the support element 12 used to distribute the contact force (arrow 24) is designed such that the contact pressure of the wiper strip 24 or of the wiping lip 28 is larger on the pane surface 26 in the middle section 36 thereof (Figure 11) than at at least one of the two end sections 38, The distribution of the contact force over the m support element occurs as a • function of various parameters of the support element such as, for example., the cross-sectional profile, the variation in the cross' section over the length of the support element, or else the profile of the radius R (s) along the support element. Optimization of the support element in the direction of a prescribed contact force distribution p(s) is therefore very complicated. The invention is based on the finding that in the case of a support element with a cross section which is essentially constant over the length of the support element, in particular a rectangular cross section, the contact force distribution p(s) can be fixed by prescribing the curvature K along a coordinate s, the coordinate s extending along the support element. The curvature K(s) is equal to the inverse radius as a function of s: K(s)= ‘ R(s) In the case of a support element, there is a relationship between the bending moment M, the radius R of the support element, the modulus of elasticity E thereof, and the areal moment of inertia I prevailing at the respective location. The relationship becomes particularly simple when it is referred to the coordinate s running with the support elements: E*I The relationship: d’K(s)_d’M(s)/ds’ ds’ ~ E*I is obtained by twofold differentiation with respect to the location s. Since the second derivative of the bending moment M with respect to the -running coordinate s corresponds directly to the contact force distribution-p along the coordinate s which is produced when the support element is pressed onto a flat pane, it follows from this that the second derivative of the curvature K with respect to the running coordinate s corresponds, except for a constant, to this contact force distribution p on a flat pane. The constant is a function of the modulus of elasticity E and of the areal moment of inertia I which, for its part, becomes very simple when a ■ rectangular cross section is involved. In the case of a prescribed, outwardly decreasing contact force distribution p, the curvature profile K(s) can be determined thereby by calculation or in simple tests. The external shape, and thus the parameters of the support element which are required for production can thereby be determined easily by the person skilled in the art. In order to consider the shape of the pane for which the wiper blade is to be used, the above relationship is to be corrected to the effect that the second derivative of the curvature Kg’i’eibe of the pane with respect to the coordinate s must be added to from [sic] the outwardly decreasing contact force distribution p, prescribed for a flat pane, along the coordinate s, which is further divided by the modulus of elasticity E and the areal moment of inertia I: d’K(s)’p(s) ‘ d’Kgeheibe(s) ds’ E*I In this regard, too, it is a simple matter for the person skilled in the art to configure a support element for a specific pane: - determining the length L and the cross-sectional profile, in particular the width b and the thickness d via empirical values, - determining a contact force" F,,"‘- - or a contact force distribution p for -a. flat pane, which ensures a good wiping quality, likewise via empirical valQ'es, - measuring the curvature profile K’’’’’’,’ of the pane, - differentiating this curvature profile Kg’’ieibe of the panes twice with respect to a coordinate s which runs with the curvature, - calculating the second derivative of the curvature profile K(s) of the support element according to the above relationship, and - twofold integration produces the desired curvature profile K(s) of the support element. It has emerged that good wiping results can be achieved when the curvature K along the running coordinate s is such that the contact pressure distribution which prevails when the wiper blade is pressed onto a flat pane is higher in a region approximately half way between the middle and end of the wiper blade than at the end of the wiper blade. This region 40 is indicated for one side in Figures 8 and 9. The invention is based on the finding that the variation in the contact force distribution p in the region 40 is of less significance than the relationship between the contact force distribution p in the region 40 to [sic] the contact force distribution p at the ends of the wiper blade. The total length L of a wiper blade is plotted in Figures 8 -and 9 in each caise, the connecting element 16 being arranged in the middle of the wiper blade, so that the wiper blade ends assume the magnitude of 0.50 L. Very good wiping results are achieved when the curvature K along a coordinate s following the longitudinal extent of the support element 12 has values such that the contact pressure distribution p which prevails when the wiper blade is pressed onto the pane to be wiped is higher in the region approximately half way between the middle and end of the wiper blade than at the end of the wiper blade. Although the consideration „of the profile of the pane for which the wiper blade is provided limits the general suitability for any desired’ panes, the selected pane is nevertheless wiped optimally. Figure 10 shows a possible curvature profile K of the support element -12, which can produce a contact force distribution p of the wiping lip 28 on the pane 15 which decreases towards the end of the wiper blade. In the case of this resilient support element 12, which when unloaded has a stronger hollow curvature with respect to the pane than the latter is curved in the region of the wipe pattern swept by the wiper blade, the curvature profile K is designed such that the latter is stronger in the middle section 36 of the support element 12 than at the end sections 3 8 thereof, A sudden swivelling over or snapping over of the wiping lip 28 from its one dragging position into its other dragging position is avoided by reducing the contact force of the wiping lip 28 on the pane surface 2 6 in the region of one wiper blade end or at both wiper blade ends. Rather, in the case of the wiper blade according to the invention there is a comparatively soft switchover of the wiping lip starting from the wiper blade end and continuing to the middle of the wiping lip for as far as the other end of the wiping lip. Figure 3 shows in conjunction with Figure 1 that even in the case of spherically curved panes the end sections of the wiping lip 28 subjec-ted to lower loading still bear effectively against the pane surface. It is common to all the exemplary embodiments that the contact pressure (arrow 24) of the wiper strip 14 on the pane 15 is larger in the middle section 36 of the latter than at at least one of its two end sections 38, This also applies even if - in contrast to the wiper blade 10, shown in terms of subject matter, with a single-piece support element 12 illustrated as a spring rail - the support element is of multipartite design. However, is may be necessary under some circumstances also to prescribev’’viQther colitis force distributions- It is then possible, however, even then to use the relationships shown to design wiper blades which achieve excellent wiping results. In the method according to the invention for producing a wiper blade, as already specified"-above the contour and the curvature profile K is [sic] determined first, and then the support element 12 is assembled with the wiper strip 14 and the connecting element 16. If the support element is constructed from two parallel flat beams', these can preferably be pre-bent with one another, that is to say directly next to one another, and this ensures that the wiper blade has a design which is very symmetrical and therefore torsion ally stable. The two halves of the support element are then to be further processed jointly in the continuing process, in order to avoid inadvertent separation. After the support element has been bent, either the wiper strip is fitted first, for example by bonding or being vulcanized on, or else, particularly in the case of two halves of the support element, by laying the halves of the support element in longitudinal grooves in the wiper strip, and then applying the connecting element. Particularly when the connecting element is welded on, the wiper strip is to be attached only subsequently, in order to avoid thermal damage to the wiper blade element. WE CLAIM: 1. A wiper blade for panes, in particular for motor vehicles, having at least one support element (12), a wiper strip (14) and a connecting means (16) for a wiper arm (18), the support element (12) being an elongated flat beam on which the wiper strip (14) and the correcting means (16) are fastened, characterized in that the support element (12) has a cross-sectional profile such that where Few is the contact force exerted by the wiper arm (18) on the wiper blade, or thru contact force for which the wiper blade was originally designed, and L is the length of the support element (12), E is the modulus of elasticity of the support element (12), lay is the moment of inertia of the cross-sectional profile about the z axis perpendicular to an s-axis running with the support element (12), and also perpendicular to a y-axis. 2. The wiper blade according to Claim 1, wherein 3. The wiper blade according to Claim 1 or 2, wherein the support element (12) has a substantially rectangular cross-sectional profile (40) with a substantially constant width b and a substantially constant thickness d. 4. The wiper blade according to any one of the preceding claims, wherein the support element (12) comprises at least two individual beams (42, 44), and in that the widths (bl, b2) of the individual beams (42, 44) add to form a total width b. 5. The wiper blade according to any one of the preceding claims, wherein the width b and thickness d of the support element (12) are selected such that 6. The wiper blade according to any one of Claims 1 to 4, wherein the width b and the thickness d of the flat beam are selected such that 7. The wiper blade for panes in particular for motor vehicle, having at least one support element (12), a wiper strip (14) and a connecting means (16) for a wiper arm (18), the support element (12) being an elongated flat beam on which the wiper strip (14) and the connecting means (16) are fastened, in particular according to any one of the preceding claims, wherein the support element (12) has a cross-sectional profile (40) which produces a lateral deflection angle of at least one of the support element ends, referred to the longitudinal extent of the support element, of y particular transverse to its longitudinal extent and the coefficient of friction between the pane (26) and wiper strip (14) is approximately 1. 8. The wiper blade for panes, in particular for motor vehicles, having at least one support element (12), a wiper strip (14) and a connecting means (16) for a wiper arm (18), the support element (12) being an elongated flat beam on which the wiper strip (14) and the connecting means (16) are fastened, in particular according to any one of the preceding claims, wherein the support element has a length L, a width b and a thickness d such that where L is specified in meters and b and d in millimetres. 9. The wiper blade according to Claim 8, wherein the support element comprises at least two spring beams whose widths add together. 10. The wiper blade for panes (15), in particular for motor vehicles, having at least one elongated support element (12), a wiper strip (14) and a connecting means (16) for a wiper arm (18) which, in an operating position, presses the wiper blade (10) onto the pane (15), the support element (12) being an elongated flat beam on which the wiper strip (14) and the connecting means (16) are fastened and which, in a position unloaded by the wiper arm (18), has a curvature, in particular according to any one of the preceding claims, wherein the curvature along a coordinate (s) following the longitudinal extent of the support element (12) has values such that the second derivative of the curvature with respect to this coordinate (s) is substantially proportional to a contact force distribution p (s) which arises when the wiper blade (10) is pressed onto a flat pane (15), and in that the contact force distribution is reduced at least towards one end. 11. The wiper blade according to Claim 10, wherein s = coordinate along the support element K (s) =" curvature of the support element M (s) = bending moment E = modulus of elasticity I , = areal moment of inertia of the support element with reference to the neutral axis, and p(s) = specific force per unit of length = contact force distribution. 12. The wiper blade for panes (15), in particular for motor vehicles, having at least one elongated support element (12), a wiper strip (14) and a connecting means (16) for a wiper arm (18) which, in an operating position, presses the wiper blade (10) onto the pane (15), the support element (12) being an elongated flat beam on which the wiper strip (14) and the connecting means (16) are fastened and which, in a position unloaded by the wiper arm (18), has a curvature, in particular according to any one of the preceding claims, wherein the curvature along a coordinate (s) following the longitudinal extent of the support element (12) has values such that the second derivative of the curvature with respect to this coordinate (s) minus the second derivative of the curvature of the pane (15) decreases from a middle region (40) towards the ends. 13. The wiper blade according to Claim 12, wherein the middle region (40) is the location of the connecting means (16). 14. The wiper blade according to any one of Claims 12 or 13, wherein s = coordinate along the support element K (s) = curvature of the support element M (s) = bending moment E = modulus of elasticity I = areal moment of inertia of the support element with reference to the neutral axis, and P (s) = specific force per unit of length = contact force distribution. 15. The wiper blade for panes (15), in particular for motor vehicles, having at least one elongated support element (12), a wiper strip (14) and a connecting means (16) for a wiper arm (18) which, in an operating position, presses the wiper blade (10) onto the pane (15), the support element (12) being an elongated flat beam on which the wiper strip (14) and the connecting means (16) are fastened and which, in the position unloaded by the wiper arm (18), has a curvature, in particular according to any one of the preceding claims, wherein the curvature along a coordinate (s) following the longitudinal extent of the support element (12) has values such that the contact pressure distribution p (s) which prevails when the wiper blade (10) is pressed onto a flat pane (15) is higher in a region (40) approximately halfway between the middle and end of the wiper blade (10) than at the end of the wiper blade (10). 16, The wiper blade for panes (15), in particular for motor vehicles, having at least one elongated support element (12), a wiper strip (14) and a connecting means (16) for a wiper arm (18) which, in an operating position, presses the wiper blade (10) onto the pane (15), the support element (12) being an elongated flat beam on which the wiper strip (14) and the connecting means (16) are fastened and which, in a position unloaded by the wiper arm (18), has a curvature, in particular according to any one of the preceding claims, wherein the curvature along a coordinate (s) following the longitudinal extent of the support element (12) has values such that the contact pressure distribution p (s) which prevails when the wiper blade (10) is pressed onto the pane (15) to be wiped is higher in a region (40) approximately halfway between the middle and end of the wiper blade (10) than at the end of the wiper blade (10). 17. The method for producing a wiper blade according to any one of the preceding claims comprising the steps of: determining the length L required for the pane to be wiped and the matched contact force Few, determining the width b and the thickness d, determining the curvature profile K (s), bending the support element, and connecting the support element, wiper strip and connecting means. 18. The method according to Claim 17, comprising the steps of: determining the length L and the cross-sectional profile, in particular the width b and the thickness d via empirical values, determining a contact force Fife or a contact force distribution p for a flat pane, which ensures a good wiping quality, likewise via empirical values, measuring the curvature profile K (s) of the pane, differentiating this curvature profile K (s) of the panes twice with respect to a coordinate s which turns with the curvature, calculating the second derivative of the curvature profile K (s) of the support element according to the above relationship, and twofold integration produces the desired curvature profile K (s) of the support element.

Documents:

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abs-in-pct-2001-314-che.jpg

in-pct-2001-314-che-abstract.pdf

in-pct-2001-314-che-claims filed.pdf

in-pct-2001-314-che-claims granted.pdf

in-pct-2001-314-che-correspondnece-others.pdf

in-pct-2001-314-che-correspondnece-po.pdf

in-pct-2001-314-che-description(complete)filed.pdf

in-pct-2001-314-che-description(complete)granted.pdf

in-pct-2001-314-che-drawings.pdf

in-pct-2001-314-che-form 1.pdf

in-pct-2001-314-che-form 26.pdf

in-pct-2001-314-che-form 3.pdf

in-pct-2001-314-che-form 5.pdf

in-pct-2001-314-che-other documents.pdf

in-pct-2001-314-che-pct.pdf