(12) United States Patent
`De Block
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,836,926 B1
`Jan. 4, 2005
`
`US006836926B1
`
`(54) WIPER BLADE FOR WINDSHIELDS,
`ESPECIALLY AUTOMOBILE WINDSHIELDS,
`AND METHOD FOR THE PRODUCTION
`
`4,045,838 A *
`5,325,564 A *
`5,485,650 A *
`
`................... .. 15/250.48
`9/1977 Porter
`
`7/1994 Swanepoel
`15/250.44
`1/1996 Swanepoel ............. .. 15/250.43
`
`THEREOF
`
`FOREIGN PATENT DOCUMENTS
`
`Inventor: Peter De Block, Halen (BE)
`(75)
`(73) Assignee: Robert Bosch GmbH, Stuttgart (DE)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 312 days.
`
`DE
`DE
`
`EP
`EP
`
`B
`i253;
`195 01 849 A1 *
`198 14 610 A
`
`8/1995
`10/1999
`
`2/1993
`0 528 643 A
`4/1994
`0 594 451 A
`OTHER PUBLICATIONS
`
`(21) Appl' No’:
`22
`PCT F'l d:
`(
`)
`1 C
`(86) PCT No.:
`
`09/786352
`l. 6 2000
`J“
`’
`PCT/DE00/02168
`
`§ 371 (C)(1)>
`(2)> (4) D3193 May 3: 2001
`
`English translation of the Abstract to DE 195 01 849 A1.*
`* cited by examiner
`
`Primary Examiner—Robert J. Warden, Sr.
`Assistant Examiner—Laura C Cole
`(74) Attorney, Agent, or Firm—Michael J. Striker
`
`(87) PCT Pub. No.: W001/03982
`
`(57)
`
`ABSTRACT
`
`PCT Pub’ Date:‘Ian' 18’ 2001
`Foreign Application priority Data
`(BE)
`
`EDIE?
`(DE)
`
`(30)
`ill? 3:
`J31‘ 9’ 1999
`Jul‘ 5’ 2000
`"""""""""""""""""""" "
`'
`’
`Int. Cl.7 ............................. .. A47L 1/00; B60S 1/02
`(51)
`(52) U.s. Cl.
`................ ..
`15/250.43; 15/250.451
`(58) Field of Search ....................... .. 15/250.43, 250.44,
`15/250.451’ 250.48’ 250.361’ 250.202’
`250.33
`
`199 31 858
`100 32 048
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`The invention relates to a Wiper blade for Windshields,
`especiallyi automobile Windshields, céorzriprising at least((1141:):
`su
`ort e ement, a su
`ort e ement
`, a W1 er stri
`anldpconnecting meansp(I16) for a Wiper arm (18)?The S1Il)ppOI‘t
`element (12) is a long fiat rod to which the Wiper strip (14)
`and the connecting means (16) are fixed. According to the
`invention,
`the fiat rod has a cross-sectional profile (40),
`whereby FW *L2/48*E*IZZ<0.009 when Fwf is the pressure
`foree exerted on the Wiper blade or the pressure force for
`Whlch the Wlper blade W35 Orlglnauy lmendeda L represiefilts
`the length of the Wiper blade, E standsifor the elasticity
`module of the fiat rod material and I2, is the moment of
`inertia of the cross-sectional profile around the Z axis
`(perpendicular to an s axis associated with the fiat rod and
`d'
`l
`t
`th
`'
`.
`perpen lcu at 0
`e y axls)
`
`3,192,551 A *
`
`7/1965 Appel
`
`................... .. 15/250.43
`
`11 Claims, 6 Drawing Sheets
`
`
`
`Costco Exhibit 1001, p. 1
`
`Costco Exhibit 1001, p. 1
`
`

`
`U.S. Patent
`
`Jan. 4, 2005
`
`Sheet 1 of 6
`
`US 6,836,926 B1
`
`Costco Exhibit 1001, p. 2
`
`Costco Exhibit 1001, p. 2
`
`

`
`U.S. Patent
`
`Jan. 4, 2005
`
`Sheet 2 of 6
`
`US 6,836,926 B1
`
`Costco Exhibit 1001, p. 3
`
`Costco Exhibit 1001, p. 3
`
`

`
`U.S. Patent
`
`Jan. 4, 2005
`
`Sheet 3 of 6
`
`US 6,836,926 B1
`
`Costco Exhibit 1001, p. 4
`
`Costco Exhibit 1001, p. 4
`
`
`

`
`U.S. Patent
`
`Jan. 4, 2005
`
`Sheet 4 of 6
`
`US 6,836,926 B1
`
`1/1
`
`4/2
`
`Costco Exhibit 1001, p. 5
`
`Costco Exhibit 1001, p. 5
`
`

`
`U.S. Patent
`
`Jan. 4, 2005
`
`Sheet 5 of 6
`
`US 6,836,926 B1
`
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`‘GYEQE (;\J.‘J‘O'a'Cd
`
`Costco Exhibit 1001, p. 6
`
`Costco Exhibit 1001, p. 6
`
`

`
`U.S. Patent
`
`Jan. 4, 2005
`
`Sheet 6 of 6
`
`US 6,836,926 B1
`
`\
`
`6
`
`0.91.
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`o.uuL
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`Costco Exhibit 1001, p. 7
`
`Costco Exhibit 1001, p. 7
`
`

`
`US 6,836,926 B1
`
`1
`WIPER BLADE FOR WINDSHIELDS,
`ESPECIALLY AUTOMOBILE WINDSHIELDS,
`AND METHOD FOR THE PRODUCTION
`THEREOF
`
`BACKGROUND OF THE INVENTION
`
`the support
`invention,
`In wiper blades of the present
`element should assure a predetermined distribution of the
`wiper blade pressing force—often also called pressure—
`applied by the wiper arm against the window, over the entire
`wiping zone that the wiper blade sweeps across. Through an
`appropriate curvature of the unstressed support element—
`i.e. when the wiper blade is not resting against the window—
`the ends of the wiper strip, which is placed completely
`against the window during the operation of the wiper blade,
`are loaded in the direction of the window by the support
`element, which is then under stress, even when the curvature
`radii of spherically curved vehicle windows change in every
`wiper blade position. The curvature of the wiper blade must
`therefore be slightly sharper than the sharpest curvature
`measured in the wiping zone of the window to be wiped. The
`support element thus replaces the costly support bracket
`design that has two spring strips disposed in the wiper strip,
`which is the kind used in conventional wiper blades (DE-OS
`15 05 357).
`The invention is based on a wiper blade as generically
`defined by the independent claims. In a known wiper blade
`of this type (DE-PS 12 47 161), a number of embodiments
`of the support elements are provided as a solution to the
`problem of producing the most uniform possible pressure
`load of the wiper blade over its entire length against a fiat
`window.
`
`In another known wiper blade of this generic type (EP 0
`528 643 B1), in order to produce a uniform pressure load of
`the wiper blade against spherically curved windows,
`the
`pressure load increases significantly in the two end sections
`when the wiper blade is pressed against a flat window.
`The uniform pressure distribution over the entire wiper
`blade length that is sought in both cases, however, leads to
`an abrupt flipping over of the wiper lip, which belongs to the
`wiper blade and performs the actual wiping function, over its
`entire length, from its one drag position into its other drag
`position when the wiper blade reverses its working direc-
`tion. This drag position is essential for an effective, quiet
`operation of the wiper system. The abrupt flipping over of
`the wiper lip, however,—which is inevitably connected with
`an up and down motion of the wiper blade—generates an
`undesirable tapping noise. In addition, the matching of the
`support element tension to the desired pressure distribution,
`which differs from case to case, is problematic with spheri-
`cally curved windows.
`EP 0 594 451 describes flat bar wiper blades with a
`varying profile, which should not to exceed a particular
`lateral deflection when a test force is applied to them. To that
`end, an extremely complex interrelationship among internal
`parameters that characterize the spring bar are used to
`determine a quantity which should not exceed a certain
`threshold value. The equation given permits only complex
`and incomplete conclusions to be reached regarding the
`actual quantities to be entered. The other data relate to an
`unstressed wiper blade so that it is hardly possible to draw
`conclusions as to the quality of a wiper blade during
`operation.
`In addition, putting the teaching of the known prior art to
`use turns out to be difficult since the available parameters
`cannot be applied directly to wiper blades to be newly
`manufactured.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`SUMMARY OF THE INVENTION
`
`The wiper blade according to the invention, with the
`features of the main claim, has the advantage of an entirely
`favorable wiping quality because among other things, a
`rattling of the wiper blade across the window—the so-called
`slip-stick effect—is prevented. This results from the knowl-
`edge that for the slip-stick effect, attention must be paid
`particularly to the lateral deflection angle and less so to the
`absolute lag, i.e. the absolute deflection of the tips under
`stress. It is therefore advantageous if the wiper blade is
`designed so that the lateral deflection of the ends of the
`wiper blades, which lag behind during operation, does not
`exceed a lateral deflection angle of a particular magnitude.
`From the quantity discovered for this angle,
`important
`parameters can then be derived for the wiper blade, which
`have a simple relation to one another and which, in this
`relation, should not exceed an upper limit of 0.009. With the
`aid of this relation and the upper limit indicated, cross
`sectional profiles for the support element can be very simply
`determined, which then produce a favorable wiping result.
`In particular, wiper blades with a constant cross section over
`their lengths are particularly easy to produce in this manner.
`Advantageous improvements and embodiments of the
`wiper blade according to the invention are possible by
`means of the measures disclosed in the remaining claims.
`The wiping quality increases further if the proportion of
`the product of the contact force and the square of the length
`to the product of 48 times the elasticity modulus of the
`support element and the IZZ moment of inertia does not
`exceed an upper limit of 0.005.
`Particularly useful cross sectional profiles are rectangular
`in design and have an essentially constant width and an
`essentially constant thickness over the length of the wiper
`blade. The support element can also be comprised of indi-
`vidual bars which are disposed laterally next to one another
`or one on top of another and their overall width or their
`overall thickness are respectively added together to produce
`an overall width and/or an overall thickness. With such a
`rectangular cross sectional profile, the moment of inertia IZZ
`can be entered as d*b3/12, where the overall thickness and
`the overall width are entered as d and b, respectively. This
`produces an easy-to-apply relation via which the support
`element can be optimized for the wiper blades if the given
`upper limits of 0.009 and particularly 0.005 are not
`exceeded.
`
`Particularly if more complex cross sectional profiles are
`chosen for the support element, which vary, for example,
`over the length of the wiper blade or have a ladder-type
`structure or the like, a favorable wiping quality can never-
`theless be achieved if consideration is given to the fact that
`the lateral deflection angle y does not exceed a
`magnitude of 0.5° and in particular 0.3° during operation
`of the wiper blade. These specifications apply for an
`average friction value y of 1 and must be correspond-
`ingly increased or decreased when there are higher or
`lower friction values.
`
`The lateral deflection angle y is the angle at which the
`tangent to the support element end intersects the axis extend-
`ing in the longitudinal direction of the support element. In a
`first approximation, this angle can also be understood to be
`the angle enclosed by the axis extending in the longitudinal
`span direction of the support element and a straight line
`passing through a support element end and the fulcrum point
`of the wiper arm on the support element.
`Very good wiping results can be achieved if the width b
`and the thickness d remain in a definite proportion to the
`
`Costco Exhibit 1001, p. 8
`
`Costco Exhibit 1001, p. 8
`
`

`
`US 6,836,926 B1
`
`3
`the
`overall length of the support element. In particular,
`product of the width and the square of the thickness should
`not exceed 40 times the square of the length and should not
`be less than 20 times the square of the length. The widths
`and/or the thicknesses of combined support elements are
`respectively added together to produce an overall width and
`overall thickness, which is then taken into consideration.
`The wiper blade according to the invention has the
`advantage that only one parameter has to be varied in order
`to adjust the outwardly decreasing contact force distribution.
`The curvature or the curvature progression along the support
`element can be preset
`in freely programmable bending
`machines. As a result, short trial runs can also be carried out
`to optimize the contact force distribution and therefore the
`curvature progression rapidly and without a great deal of
`expense. It is particularly advantageous if the coordinate that
`governs the curvature progression extends along the inertial
`element. This eliminates the need for complex reverse
`calculations in a Cartesian coordinate system in which each
`change in a position x requires a shifting of the subsequent
`“x values”.
`The mathematical association between the second deriva-
`
`tive of the curvature as a function of the adapted coordinate
`and the contact force progression likewise as a function of
`the adapted coordinate is particularly simple if the elasticity
`modulus of the support element material and the surface
`moment of inertia of the support element are constant over
`its length. With a preset contact pressure distribution, the
`curvature can then be directly calculated through double
`integration or also numerically.
`An optimal adaptation of such a wiper blade to windows
`with a complex curvature progression is also possible if the
`curvature of the window is subtracted from the curvature of
`
`10
`
`15
`
`20
`
`25
`
`30
`
`the support element or the second derivative of the curvature
`of the window is subtracted from the second derivative of
`
`35
`
`4
`wiper strip and the connecting element. However, it is also
`possible to attach the connecting element to the support
`element first and then to add the wiper strip.
`
`DRAWINGS
`
`FIG. 1 is a perspective representation of a wiper blade that
`is placed against the window and is connected to a wiper arm
`which is loaded toward the window,
`FIG. 2 is a schematic side view of a wiper blade, which
`is placed in an unstressed state against the window, in a
`reduced scale compared to FIG. 1,
`FIG. 3 shows the sectional plane of an enlarged section
`through the wiper blade according to FIG. 1, along the line
`III—III,
`FIGS. 4 and 5 show a variant of FIG. 3,
`FIGS. 6 and 7 show a wiper blade in a different
`embodiment, with a coordinate system sketched in,
`FIGS. 8 and 9 respectively show calculated and measured
`values for the contact force distribution plotted over the
`length of the wiper blade, and
`FIG. 10 is a schematic side view, not to scale, of a support
`element belonging to’the wiper blade.
`DESCRIPTION OF THE EXEMPLARY
`EMBODIMENT
`
`Awiper blade 10 shown in FIG. 1 has an elongated, spring
`elastic support element 12, which is also referred to as a flat
`bar, for a wiper strip 14, which is shown separately in FIG.
`10. As shown in FIGS. 1, 3, and 4, the support element 12
`and the wiper strip 14 are connected to each other with their
`longitudinal axes parallel. On the top side of the support
`element 12 remote from the window 15 to be wiped—shown
`with dot-and-dash lines in FIG. 1—, there is a connecting
`mechanism in the form of a connecting device 16 which can
`detachably connect the wiper blade 10 to a driven wiper arm
`18 that is guided on the body of the motor vehicle. The
`elongated rubber elastic wiper strip 14 is disposed on the
`underside of the support element 12 oriented toward the
`window 15.
`
`A hook, which serves as a counterpart connection means,
`is formed onto the free end 20 of the wiper arm 18 and
`engages a pivot bolt 22 that is part of the connecting device
`16 of the wiper blade 10. The securing between the wiper
`arm 18 and the wiper blade 10 is achieved by an intrinsically
`known securing mechanism, which is not shown in detail
`and is embodied in the form of an adapter.
`The wiper arm 18, and therefore also its hook ends 20, is
`loaded in the direction of the arrow 24 toward the window
`
`15 to be wiped, whose surface to be wiped is indicated with
`a dot-and-dash line 26 in FIGS. 1 and 2. The contact force
`
`40
`
`45
`
`50
`
`the curvature of the support element. In this instance, a
`contact force distribution can be preset in the same way that
`is desirable for a wiper blade that is pressed against a flat
`window. The difference between the second derivatives of
`
`the respective curvatures is then once more proportional to
`this contact force distribution.
`
`A wiper blade according to the invention excels in that
`without special adaptation, an excellent wiping result is
`achieved for average window types. The very simple steps
`taken result in the fact that the contact force distribution
`
`fulfills the requirements in most cases. The support points
`mentioned above are sufficiently precise to use as the basis
`for a curvature progression to be maintained.
`Even with complex window curvature progressions, the
`wiping quality can be increased by presetting the contact
`force distribution to particular support points. It is never-
`theless possible to design the wiper blade without complex
`calculations. The curvature progression can be essentially
`predetermined and can be optimized by means of simple
`trials. An excellent wiping quality is assured as long as the
`prerequisites are met that the contact force distribution that
`prevails when the wiper blade is pressed against the window
`to be wiped is greater in a region approximately halfway
`between the center and the end of the wiper blade than it is
`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-curved so that
`its curvature
`progression fulfills at least one of the conditions mentioned
`above. As a result, it is particularly favorable to bend the
`support element first and then to put it together with the
`
`Fwf (arrow 24) places the wiper blade 10 with its entire
`length against the surface 26 of the window 15 to be wiped.
`Since the dot-and-dash line 26 shown in FIG. 2 is
`
`55
`
`intended to represent the sharpest curvature of the window
`surface in the vicinity of the wiping zone, it is clear that the
`curvature of the wiper blade 10, which is as yet unstressed
`and rests with its two ends against the window, is sharper
`than the maximal curvature of the spherically curved win-
`dow 15. When the contact force Fwf (arrow 24) is applied,
`the wiper blade 10 rests with its wiper lip 28, which is part
`of the wiper strip 14, over its entire length against the
`window surface 26. This produces a tension in the band-like,
`spring elastic support element 12, which ensures a proper
`contact of the wiper strip 14 or rather the wiper lip 28 over
`its entire length against
`the vehicle window 15. During
`
`60
`
`65
`
`Costco Exhibit 1001, p. 9
`
`Costco Exhibit 1001, p. 9
`
`

`
`US 6,836,926 B1
`
`5
`wiper operation, the wiper arm 18 moves the wiper blade 10
`lateral to its longitudinal span, across the window 15. In
`FIG. 1, this wiping or working motion is indicated by the
`double arrow 29.
`
`The particular embodiment of the wiper blade according
`to the invention will now be discussed in detail below. As
`
`shown in FIG. 3, not to scale, the wiper strip 14 is disposed
`on the lower band surface of the support element 12,
`oriented toward the window 15. Spaced apart from the
`support element 12, the wiper strip 14 is indented on its two
`longitudinal sides so that a tilting hinge 30 remains in its
`longitudinal center region, which extends over the entire
`length of the wiper strip 14. The tilting hinge 30 transitions
`into the wiper lip 28, which has an essentially wedge-shaped
`cross section. The contact force (arrow 24) presses the wiper
`blade or rather the wiper lip 28 against the surface 26 of the
`window 15 to be wiped, and as a result of the wiping
`motion—of which FIG. 3 particularly shows the one of the
`two opposite wiping motions (double arrow 29) indicated by
`the direction arrow 32—the wiper lip 28 tilts into a so-called
`drag position, in which the wiper lip is supported along its
`entire length against the part of the wiper strip 14 that is
`secured to the support element 12. This support, which is
`indicated with the arrow 34 in FIG. 3, always takes place—
`depending on the respective wiping direction (double arrow
`29 and arrow 32, respectively)—against the upper edge of
`the wiper lip 28 disposed toward the rear in the respective
`wiping direction so that the wiper lip 28 is always guided
`across the window in a so-called drag position. This drag
`position is required for an effective, quiet operation of the
`wiper device. The reversal of the drag position takes place
`at the so-called reversal position of the wiper blade 10, when
`the blade changes its wiping direction (double arrow 29). As
`a result, the wiper blade executes an up and down motion
`which is necessitated by the tilting over of the wiper lip 28.
`The upward motion occurs counter to the direction of the
`arrow 24 and consequently also counter to the contact force.
`In the opposite wiping direction from the arrow 32, a mirror
`image of FIG. 3 is consequently produced.
`
`FIG. 4, which is an enlarged depiction in comparison to
`the wiper blade in FIG. 1, shows a cross sectional profile 40
`that has a rectangular sectional plane with a width b and a
`thickness d. In addition, a coordinate system is shown above
`the support element 12. An s-coordinate, which follows the
`curvature of the support element 12,
`is shown as a 3”’
`coordinate in FIG. 6 and the y- and Z-coordinates are
`perpendicular to it. If the wiper blade 10 is now pressed with
`a force Fwf (arrow 24) against a window 26, particularly by
`the wiper arm 18, a certain force distribution p(s)
`is
`produced, which produces a moment M(s) that is maximal
`in the center of the support element 12. For a constant
`contact force distribution
`
`and consequently,
`
`M(s) = Fwf *
`
`For an outwardly decreasing contact force distribution,
`which is particularly suitable for tilting wiper lips over, the
`moment M(s) over its entire length is somewhat less than the
`moment calculated for a constant force distribution:
`
`M(s)<p*
`
`If one then assumes that a friction value y for a dry
`window is approximately 1,
`the lateral moment during
`operation is equal to the bending moment M(s), which in
`particular is a result of the preset force distribution p(s).
`Based on the lateral bending moment, a lateral deflection
`angle y can be inferred, which can be calculated by integra-
`tion of the individual deflections from the fulcrum point of
`the wiper arm on the wiper blade to the wiper blade end. In
`the case of a centrally disposed connecting device 16, the
`deflection angle is calculated according to the equation:
`
`_f‘”M<s)dS
`7" 0
`E*1,,
`
`In view of the relation of the moment for a constant
`
`contact force distribution, a simple estimate for the angle y
`is obtained by:
`
`M? —§>
`
`45
`
`7 <
`
`0
`
`Integration yields the equation:
`
`’y<
`
`_ FWf*L2
`p*L3
`48>r<E*IZZ _ 48>:<E*IZZ
`
`Among other things, the invention is based on the knowl-
`edge that a favorable wiping quality, particularly due to
`rattle prevention, is achieved if the angle y does not exceed
`the value 0.5° (=0.009 rad) and in particular, 0.3° (=0.005
`rad). As a result, a simple relation can be deduced between
`the contact force and the geometric dimensions of the wiper
`blade, according to which
`
`Fwf * L2
`48>:<E>r<IZZ
`
`< 0.009,
`
`in particular <0.005.
`For the most frequently occurring case of a rectangular
`profile 40, as shown in FIGS. 8 and 9, the moment of inertia
`is determined by:
`
`d*b3
`12
`
`1“:
`
`where
`
`d=thickness of the support element
`
`Costco Exhibit 1001, p. 10
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`Costco Exhibit 1001, p. 10
`
`

`
`7
`b=width of the support element.
`The width b and the thickness d must therefore be selected
`so that
`
`8
`
`d2K(s) _ d2M(s)/dsz
`dsl
`‘
`E*I
`
`US 6,836,926 B1
`
`Fwf * L2
`
`< 0-009»
`
`in particular <0.005.
`If the support element 12 is divided into two separate
`spring bars 42 and 44, as shown in FIG. 5, then in the above
`considerations in the first approximation, the width b can be
`assumed to be the sum of the individual widths b1 and b2:
`
`b=b1+b2. Hence simple relations between the width and
`thickness of a support element can also be deduced for
`systems of this kind.
`For the case in which a rectangular cross sectional profile
`is not selected, it is then necessary to determine the moment
`of inertia I22 and to correspondingly insert it into the rela-
`tions mentioned above. Likewise, cross sectional changes
`over the length of the wiper blade or a non-central fulcrum
`point of the wiper arm on the wiper blade must also be
`correspondingly taken into account in the above consider-
`ations.
`
`In order to achieve the quietest possible tilting over of the
`wiper lip 28 from its one drag position into its other drag
`position, the support element 12 that is used to distribute the
`contact force (arrow 24) is designed so that the contact force
`of the wiper strip 24, or rather the wiper lip 28, against the
`window surface 26 is greater in its middle section 36 than in
`at least one of the two end sections 38.
`
`The distribution of the contact force over the support
`element occurs as a function of various parameters of the
`support element such as the cross sectional profile, the cross
`sectional progression over the length of the support element,
`or also the radius progression R(s) along the support ele-
`ment. An optimization of the support element in the direc-
`tion of a predetermined contact force distribution p(s) is
`therefore very complex. The invention is based on the
`knowledge that in a support element with an essentially
`constant, in particular rectangular cross section over the
`length of the support element, the contact force distribution
`p(s) can-be established by predetermining the curvature K
`along a coordinate s, which coordinate s extends along the
`support element. The curvature K(s) is equal to the inverse
`radius as a function of s:
`
`In the support element, there is a relation between the
`bending moment M, the radius R of the support element, its
`elasticity modulus E, and the surface moment of inertia I
`prevailing at the respective location. The relation is particu-
`larly simple when it is related to the coordinate s, which
`adapts along with the support elements:
`
`Double differentiation as a function of the location s
`
`yields the relation:
`
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`Since the second derivative of the bending moment M as
`a function of the adaptive coordinate s is equal to the contact
`force distribution d along the coordinate s, which arises
`when the support element is pressed against a window, then
`it follows from this that the second derivative of the curva-
`
`ture K as a function of the adaptive coordinate s coincides
`with this contact force distribution p against a flat window,
`with the exception of a constant. The constant depends on
`the elasticity modulus E as well as on the surface moment of
`inertia I which for its part, is very simple if the cross section
`in question is rectangular. When there is a preset, outwardly
`decreasing contact force distribution p, the curvature profile
`K(s) can be determined mathematically or by simple experi-
`mentation. The geometry and therefore the parameters of the
`support element that are required for manufacture are there-
`fore easy for a specialist to determine.
`In order to take into account the shape of the window for
`which the wiper blade should be used, the above relation
`should be adjusted such that based on the contact force
`distribution p along the coordinate s—which distribution is
`predetermined for a flat window, decreases toward the
`outside, and is also divided by the elasticity modulus E and
`the surface moment of inertia I—, the second derivative of
`the curvature Km-MOW of the window as a function of the
`coordinate s must be added to it:
`
`d2I<<s> _ p(s) + d2KW.,w<s)
`dsz
`— E *1
`J52
`
`it is also easy for the specialist to
`By means of this,
`configure a support element for a particular window:
`determination of the length L and the cross sectional
`profile, particularly the width b and the thickness d by
`means of experimental values,
`
`determination of a contact force Fwf and a contact force
`distribution p for a flat window, which assures a favor-
`able wiping quality, likewise by means of experimental
`values,
`measurement of the curvature progression KW
`window,
`double derivation of this curvature progression Km-"dew
`Of the window as a function of a coordinate that adapts
`along with the curvature,
`calculation of the second derivative of the curvature
`
`of the
`
`indow
`
`progression K(s) of the support element according to
`the above relation,
`double integration yields the desired curvature progres-
`sion K(s) of the support element. It has turned out that
`favorable wiping results can be achieved if the curva-
`ture K along the adaptive coordinate a is such that the
`contact force distribution, which prevails when the
`wiper blade is pressed against a fiat window, is greater
`than in a region approximately halfway between the
`center and the end of the wiper blade than it is at the end
`of the wiper blade. FIGS. 8 and 9 show this region 50
`for one side. The invention is based on the knowledge
`is of less significance than the relation between e that
`the progression of the contact force distribution p in the
`region 50 to the contact force distribution p at the ends
`of the wiper blade. The overall length L of a wiper
`blade is plotted in FIGS. 8 and 9, respectively, in which
`
`Costco Exhibit 1001, p. 11
`
`Costco Exhibit 1001, p. 11
`
`

`
`US 6,836,926 B1
`
`9
`the connecting element 16 is disposed in the center of
`the wiper blade so that the wiper blade ends each
`occupy the value 0.5 L.
`Very favorable wiping results are achieved if the curva-
`ture K along a coordinate s that follows the longitudinal span
`of the support element 12 has values such that the contact
`force distribution p that prevails when the wiper blade is
`pressed against the window to be wiped is greater in the
`region approximately halfway between the center and the
`end of the wiper blade than it is at the end of the wiper blade.
`Although taking into account the window shape for which
`the wiper blade is provided does in fact limit the blade’s
`general suitability for arbitrary window types, it also results
`in the fact that the selected window is wiped in an optimal
`manner.
`
`FIG. 10 depicts a possible curvature progression K of the
`support element 12, which can produce a contact force
`distribution p of the wiper lip 28 against the window 15,
`which decreases toward the wiper blade end. With this
`spring elastic support element 12 which, when unstressed,
`has a sharper hollow curvature toward the window than this
`window has in the vicinity of the wiping zone swept by the
`wiper blade, the curvature progression K is designed so that
`it is sharper in the middle section 36 of the support element
`12 than in its end sections 38.
`
`Reducing the contact force of the wiper lip 28 against the
`window surface 26 in the vicinity of one wiper blade end or
`at both wiper blade ends prevents the wiper lip 28 from
`abruptly flipping over or snapping over as it moves from its
`one drag position into its other drag position. On the
`contrary, with the wiper blade according to the invention the
`wiper lip turns over in a comparatively gentle manner,
`starting from the end of the wiper blade, moving to the
`center of the wiper lip, and continuing on to the other end of
`the wiper lip. In combination with FIG. 1, FIG. 3 shows that
`even with spherically curved windows, the less intensely
`stressed end sections of the wiper lip 28 still rest against the
`window surface in an effective manner.
`
`It is common to all of the exemplary embodiments that the
`contact force (arrow 24) of the wiper strip 14 against the
`window 15 is greater in its middle section 36 than in at least
`one of its two end sections 38. This is also the case when—in
`
`contrast to the wiper blade 10 graphically represented, with
`a one-piece support element 12 depicted as a spring strip—
`the support element is embodied as having several parts. In
`certain circumstances, however, it can also be necessary to
`preset other contact force distributions. But even then, wiper
`blades which produce excellent wiping results can be
`designed using the relations demonstrated.
`As has already been indicated above, with the method
`according to the invention for producing a wiper blade, first
`the contour and the curvature progression K are determined
`and then the support element 12 is put together with the
`wiper strip 14 and the connecting element 16. If the support
`element is comprised of two parallel, fiat bars, these can
`preferably be pre-curved with each other, i.e. directly next to
`each other, which assures a very symmetrical and therefore
`torsionally stable design of the wiper blade. Later in the
`process, the two support element halves must then be further
`processed in order to prevent an inadvertent separation.
`After the support element has been curved, either the wiper
`blade is first mounted, for example by means of being glued
`in place or vulcanized in place, or in particular, when there
`are two support element halves, by means of insertion of the
`support element halves into longitudinal grooves of the
`wiper strip, and then the connecting element is mounted. In
`particular, if the connecting element is welded on, the wiper
`
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