United States Patent 1191 1
`Cone
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`[54] FIBER-LOADED WINDSIIIELD WIPER
`SUPERSTRUCTURE
`[75] Inventor: Irwin C. Cone, Littleton, C010.
`[73] Assignee: The Gates Rubber Company,
`Denver, C010.
`July 15, 1974
`[22] Filed:
`[21] Appl. No.2 488,372
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`[52] US. Cl. ........................................... .. 15/250.42
`[51] Int. Cl.2 ........................................... .. B605 1/02
`[58] Field of Search ..... .. 15/250.35, 250.36, 250.42;
`260/4218; 264/108, 24; 161/170
`
`[56]
`
`References Cited
`UNITED STATES PATENTS
`
`3,178,753
`
`4/1965 Wise . . . . . . . . . . .
`
`, . . . .. 15/250.42
`
`3,348,257
`
`10/1967 Hadekel . . . . . .
`
`. . . . .. 15/250142
`
`3,404,203
`
`10/1968 Donald . . . . . . . . . . .
`
`. . . . . . . .. 264/108
`
`3,684,645
`3,820,188
`
`8/1972 Temple et a1 ............. .. 161/170 )4
`6/1974 Moorhead et a1. ............ .. 15/250.42
`
`3,925,844
`[11]
`[45] Dec. 16, 1975
`
`3,837,033
`9/1974 van den Berg et a] ......... .. 15/250.32
`FOREIGN PATENTS OR APPLICATIONS
`
`1,090,122
`1,211,737
`
`9/1960 Germany .................... .. 15/250.42
`11/1970
`United Kingdom ............... .. 264/108
`
`Primary Examiner—Peter Feldman
`Attorney, Agent, or Firm—Curtis H. Castleman, .lr.;
`Raymond Fink; H. W. Oberg, Jr.
`
`ABSTRACT
`[5 7]
`The invention discloses a windshield wiper superstruc
`ture yoke or lever ann fabricated of a polymeric ma
`trix molded to the desired shape ‘and in which is em
`bedded through at least a portion of the length of the
`yoke ?brous material whose tensile strength is greater
`than that of the polymeric matrix. At least near the
`outer surfaces of the yoke the ?brous material is ori
`ented predominantly longitudinally with respect to the
`lengthwise direction of the yoke and/or parallel or tan
`gential to its outer surface.
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`11 Claims, 4 Drawing Figures
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`Costco Exhibit 1024, p. 1
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`

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`US. Patent Dec. 16, 1975
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`3,925,844
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`Costco Exhibit 1024, p. 2
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`

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`3.925'I814
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`vFIG. 2 is a perspective view of the primary-yoke-of
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`. > FIG. 1; and . FIGS. 3 and 4 are respective partial longitudinal -. > ' » -‘
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`sectional views taken along sections 3-3 and 4-4 of
`FIG..2; shown schematically.
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`v PREFERRED EMBODIMENTS OF ' V I INVENTION
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`Referring to the; drawings, a wiper assembly which
`may be used in conjunction with. the windshield of an
`automobile, for instance, is generally designated at- 10.
`A wiper, actuator arm‘ (not shown) has its free end
`engageable‘ with an attaching clip in known manner
`(not shown) whichyin turnv is pivotally mounted to
`transverse central bore 12 of the wiper assembly. In
`general, the‘ wipericonsists of av pressure-distributing
`superstructure which may be of various con?gurations,
`exempli?ed by a pair of secondary yokes 16, 16’ con
`nected intermediate their respective ends to a primary
`yoke lever 14 intermediately of which is positioned the
`aforementioned bore. The wiper assembly is completed
`by a blade subassembly or re?ll comprised of a squee
`gee support backing strip 18 and a conventional elasto
`meric wiping element or squeegee 20 held by the back
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`ing strip.
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`Each secondary yoke 16, 16' contains two pairs of
`transversely aligned or staggered claws 22 which slid
`ably connect thesuperstructure to the blade subassem
`bly maintaining it in operative association. While the
`superstructure is shown as being articulated with pin
`connections 24, 24' between the primary and second
`ary yokes, it will be understood that the superstructure
`can be formed 'of a unitary molded polymeric member.v
`In FlG.>2 are shown the end connection transverse
`bores 28, 28' through which the pins 24, 24' fasten
`together the primary and secondary yokes._These end
`bores together with the central bore ‘12-‘form connec-
`tion zones normally subject to stress fatigue during
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`operation.
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`, According to the invention, at least one and prefera
`bly all of_,the yoke' or lever portions of the superstruc
`ture are made of a ‘polymeric material having embed
`ded, therein throughout the length of such, yoke ?brous
`material such ‘as glass ?bers shown schematically at 26.
`Suitable weather resistant polymeric materials include
`acetal, nylon and polycarbonate resins. A particularly
`preferred material because of its flexural strength,
`chemical resistance, and processing compatibility with
`glass ?bers is type 6/6 nylon (polyhexamethylene adip
`amide).
`I
`The ?brous loading material has a tensile strength
`exceeding and preferably at least 10 times and more
`preferably at least 20 times that of the polymeric matrix
`in which it is embedded. Various types of ?brous mate
`rials may be employed, exempli?ed by metallic ?bers in
`the form of whiskers,.for instance, inorganic non-met
`allic ?bers such as the aforementioned ?ber glass, and
`organic fibers ‘such as polyester, or aramides such as
`Kevlar (a registered trademark. of the duPont Com
`pany). Preferably the fibers form a mechanical or
`chemical bond'with the polymeric matrix.
`I
`The length of .the ?bers is not narrowly critical and
`they may range from about one thirty-second up‘. to
`about one-half inch, although preferably the length is in
`the range from about one-sixteenth to about one-eighth
`inches for enhanced processing. The longer ?bers offer
`greater resistance to. crazing and maximum ?exural
`strength, although more dif?cult to injection mold.
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`' FIBER-LOADED WINDSHIELD WIPIERI
`
`SUPERSTRUCTURE
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`_ BACKGROUND OF THE INVENTION
`This inventionrelates to windshield cleaning devices
`and particularly to plastic superstructures or holders in
`which is engaged the customary elastomeric wiping
`member with its associated backingmember.
`The use of plastic yokes in the superstructures of
`windshield wiper blades has‘ gained impetus. Unlike
`their metal counterparts, the plastic yokes do not rattle,
`re?ect glare, cut ?ngers or scratch Windshields to any
`signi?cant degree. Polymeric materials such as polycar
`bonate have been used extensively in'this respect. How
`ever, the superstructure vyokes fabricated of plastic
`materials may present problems with respect to dimen
`sional stability, e.g., creep under continuous loading,
`and problems with stress cracking ofv the polymeric
`matrix particularly atlor near the connection zones of
`the superstructure, e.g., at pin ‘connection bores, which
`are inherently vulnerable ‘to stress ‘fatigue. The afore
`mentioned problems can be accentuated‘ when .the
`blades are subjected to abnormal use, such asmay be
`created by above normal wiper arm loading and expo
`sure to adverse chemical environments such as found in
`certain windshield washer solutions.
`The problem with stress cracking or,crazing can be
`particularly destructive. The‘ blade as it is flexed in its
`to and fro oscillation across the windshield can cause
`any cracks which have been formed in its surface to
`grow and eventually cause failure of the blade by frac
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`turing.
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`It. is a, primary object of the present invention to
`overcome problems which may occur with the use of
`plastic yokes in the superstructures of windshield
`blades,. and particularly to provide a superstructure
`yoke highly resistant to; creep under load and resistant
`to failure due to initiation‘and propagation of cracks in
`the polymer matrix. .It is arfurther object to produce a
`superstructure of very high ?exural strength and resis
`tance to chemicaland weatherin?uences. .
`SUMMARY OF THE INVENTION
`Brie?y described, the invention is drawn to elongated
`yokes or levers for assembly ‘in a windshield. wiper su
`perstructure comprising a polymeric matrix in which is
`embedded through at least a signi?cant portion of the
`length of the yoke ?brous material having a tensile
`strength greater than that of the material of the poly
`meric matrix. At least near the outer surface of the
`yoke a preponderance of the?bers are oriented 'sub
`stantially lengthwise or longitudinallywith‘respect to
`the elongated yoke. Near the surface of the portions of
`the yoke for connection with anotheryokeor wiper
`arm connector, a preponderance of the ?bers-are ori
`ented substantially parallel or tangentially with ‘respect
`to “the connection portions and liein 'a plane substan
`tially longitudinal with respect to the yokev and substan
`tially normal to the windshield'surface to be wiped.
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`BRIEF DESCRIPTION OF THE DRAWINGS »
`This invention will be described "in conjunction with
`the following FIGURES which depict certain preferred
`aspects of the invention, and in which:
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`FIG. 1 is a side elevational view of a iwiper blade
`having the yokes constructed according tothe subject
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`invention;
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`Costco Exhibit 1024, p. 3
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`Desired end properties such as ?exibility of the yoke
`longitudinally with respect to the yoke at the top and
`will dictate the length to diameter ratio of the ?bers.
`base of such connecting bores, and in general substan
`A satisfactory method for fabricating the ?ber ?lled
`tially parallel to the surface’ of the connection portion
`plastic yoke members is to form a mixture of a poly
`taken in longitudinal cross-section. for instance tangen
`meric melt with entrained ?bers and then injection
`tially to the bore 12, 28 as shown in FIGS. 3 and 4, and
`mold the mixture into a mold cavity of desired elon
`in a plane perpendicular to the surface to be wiped by
`gated con?guration. The amount of ?ber loading will
`the windshield wiper structure.
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`be determined by processability together with desired
`It is a further advantage that the ?brous material in
`?nal characteristics, although preferably it has been
`most instances will reduce the water take-up of the
`found that from about 20 to about 45 percent by weight
`polymeric material, if the polymeric material is nor
`of the completed ?ber loaded plastic yoke is formed of
`mally inclined to do so. Many polymeric materials lose
`the ?brous loading material, with the more preferred
`?exural strength with water absorption. For instance,
`range being from about 30 to about 40 percent by
`one commercial type of 6/6 nylon unloaded has a satu
`weight ?ber loading based on the ?nished article. Ma
`rated moisture content of 8.5 percent whereas its 33
`terials which have been found suitable are 6/6 nylon
`percent glass-?lled counterpart has a saturation mois
`loaded with from 25 to about 40 percent short glass
`ture content of only 5.3 percent, with a consequential
`?bers (less' than about one-eighth inch in length). This
`increased ?exural strength in the glass loaded material.
`latter material, when loaded with 40 percent glass
`Additional advantages which the ?ber-?lled poly
`(short ?bers) exhibits a ?exural strength (ASTM D
`meric materials of the subject invention offer with re
`spect to windshield wiper yokes are improved resis
`790-71) of 48,000, as molded, contrastedwith a ?ex
`ural strength of only 17,000 for the same nylon without
`tance to creep (i.e., improved dimensional stability)
`glass loading. At equilibrium moisture of 50 percent
`and increased impact strength. In the former case, the
`relative humidity the glass ?lled nylon has a flexural
`yoke members will maintain their respective shape and
`strength of 35,000 compared with 6,100 for the unrein
`therefore retain the desired clearance and curvature
`forced counterpart. High ?exural strength is crucial
`between the yoke members 14, l6, l6’ and the backing
`toward meeting the objects of the invention, and in
`member 18 permitting the necessary pivotal deflection
`general it is preferred that the yoke have a ?exural
`required at pivot points 24, 24' for conformance to
`strength of at least 20,000 and more preferably at least
`acutely curved Windshields. In the case of impact
`45,000 psi, as molded.
`strength, it is well known that if the wiper arm is out of
`adjustment the wiper blade may be subjected to bang
`Orientation of the ?bers within the polymer matrix is
`ing against the molding associated with the windshield
`critical insofar as a predominant portion of the ?bers
`are oriented substantially lengthwise or longitudinally
`and for this reason the blade must resist these continual
`impacts. The oriented ?ber loading of the polymeric
`with respect to the length of the yoke member. In other
`matrix according to the subject invention easily pro
`words, more of the ?bers are oriented substantially
`longitudinally with respect to the yoke than in any
`vides such resistance for long life.
`other single direction. Such orientation occurs primar
`It should be understood that the invention is capable
`ily near the surface of the yoke, e.g., within about 0.080
`of a variety of modi?cations and variations which will
`inches of the outer surface. Fibers characterized by
`be made apparent to those skilled in the art by a read
`ing of the speci?cation and which are to be included
`such orientation are shown at 30, for instance. The
`within the sphere of the claims appended hereto.
`farther from the surface, the more random the orienta
`tion generally becomes. Close to the surface of the
`‘What is claimed is:
`‘1. An elongated yoke for a windshield wiper super
`yoke, i.e., within about 0.030 inches of the surface, it is
`structure comprising:
`preferred that at least a majority and more preferably
`at least 85 percent of the ?bers are oriented within
`a polymeric matrix in which is embedded through at
`about 10° of the longitudinal axis of the yoke. The
`least a portion of the length of the yoke' ?bers hav
`result is greatly improved ?exural strength and resis
`. ing a tensile strength greater than that of the poly
`tance to bending forces created by the loads of the
`meric matrix alone, more of said ?bers being ori
`ented substantially longitudinally with respect to
`wiper arm attached to the primary yoke of the super
`' ‘the; elongated yoke than in any other single direc
`structure.
`By orienting the ?bers in the longitudinal direction
`tion, such longitudinal orientation being more
`and particularly near the surface of the yoke, the pro
`prevalent near the outer surface of the yoke than
`pensity of the yoke to form surface cracks due to im
`inward of such outer surface.
`2. Aiwindshield wiper pressure transmitting super
`posed stresses is signi?cantly reduced because the ?
`bers reinforce and hold the polymeric body in a single
`structure including at least one ?exible elongated plas
`tic yoke member, said yoke comprising:
`unitary piece. The ?bers act as a bridge or binder, and
`further by virtue of being bonded (in the preferred
`a rriolded polymeric matrix reinforced with ?brous
`embodiment) to the polymeric body, resist the initia
`material present in amount from about 20 to about
`45 percent by weight based on the yoke member,
`tion of ?ssures or cracks at the surface portion of the
`said ?brous material having ?ber lengths in the
`yoke whether in tension or in compression. Even if
`stress cracking does begin to occur, the ?bers will resist
`range of from about one thirty-second to about
`propogation and enlargement of the cracks by the bind
`one-half inch and having a tensile strength greater
`ing or bridging function which they provide and thus
`than the polymer of the polymeric matrix and at
`will prevent failure of the blade in operation.
`least near the outer surface of the yoke the ?brous
`material is predominantly oriented in a lengthwise
`In a similar manner, those portions of the yoke which
`direction with respect to the yoke.
`will form a connection with another yoke, connector,
`3. The superstructure of claim 2 wherein the poly
`wiper arm, or the like, are often formed of transverse
`bores 12, 28, 28' or similar openings in the yoke and in
`meric material is selected from the group consisting of
`acetal, nylon and polycarbonate.
`these cases the ?bers will preferably orient themselves
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`Costco Exhibit 1024, p. 4
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`3,925,844
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`9. The yoke of claim 6 wherein within a zone of about
`0.030 inches from the surface at least a majority of the
`?bers within the zone are oriented within about 10° of
`the longitudinal axis of the yoke.
`10. In a windshield wiper having an elongated plastic
`yoke member including a transverse bore therein for
`connection with a wiper arm or other yoke member,
`the improvement comprising:
`?brous loading material embedded in said plastic and
`in the vincinity of said bore oriented substantially
`parallel with respect to the bore surface as longitu
`dinally sectioned and in a plane perpendicular to
`the plane of the windshield to be wiped.
`11. A windshield wiper comprising:
`a wiping element retention member in engagement
`with and supporting the wiping element;
`an articulated superstructure for transmitting pres
`sure to the wiping element and its retention mem
`ber, said superstructure comprising an elongated
`primary yoke and a pair of elongated secondary
`yokes connected intermediate their ends to the
`primary yoke, at least one of said yokes being fabri
`cated of a plastic material;
`means for attaching the secondary yokes to the wip
`ing element retention member;
`?brous loading material embedded within said plastic
`yoke and oriented near the outer surface of said
`plastic yoke predominantly longitudinally with re
`spect to the lengthwise direction of the windshield
`wiper, and said ?brous loading material being pro
`gressively more randomly oriented as the distance
`increases from the outer surface of the plastic
`yoke.
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`4. The superstructure of claim 3 wherein the ?brous
`material is selected from the group consisting of metal
`lic ?bers, ?ber glass. polyester ?bers and ?bers made
`from aramides.
`5. The superstructure of claim 2 wherein the ?brous
`material is ?ber glass.
`6. In a windshield wiper having an elastomeric wiping
`member held by a backing member, and a pressure
`transmitting and distributing superstructure attached to
`the backing member, said superstructure comprising at
`least one ?exible elongated molded plastic yoke mem
`ber, the improvement comprising:
`?brous loading and reinforcing material embedded
`within the plastic and predominantly oriented
`along or near the surface of the plastic yoke sub
`stantially longitudinally with respect to the wind
`shield wiper;
`said plastic yoke member with embedded ?brous
`loading having a ?exural strength of at least about
`20,000 psi, as molded.
`7. The windshield wiper of claim 4 wherein the ?ex
`ural strength of the plastic yoke member with embed
`ded ?brous loading is at least about 45.000 psi, as
`molded.
`8. A ?exible yoke for a windshield wiper superstruc
`ture resistant to stress cracking and crack propogation
`comprising:
`an elongated polymeric body made of ?ber glass
`loaded-nylon having a ?exural strength of at least
`20,000 psi, the predominant portion of said ?bers
`near the surface of the yoke being oriented sub
`stantially longitudinally with respect to the yoke
`length, and the predominant portion of said ?bers
`away from the surface of the yoke being oriented
`substantially randomly.
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`Costco Exhibit 1024, p. 5