CA1327680C - Heated wiper blade assembly - Google Patents

Abstract

HEATED WIPER BLADE ASSEMBLY

ABSTRACT OF THE DISCLOSURE
A heated wiper blade assembly for windshields is provided, in which a plastic blade holder has an upper longitudinal groove for receiving a flat electric heating element enclosed in a ribbon of dielectric. The plastic blade holder also has at its lower portion, a longitudinal slot for receiving a wiper blade therein. A metal cap is positioned over the heating element and crimped around the plastic holder to form a wiper blade subassembly. Such subassembly is then mounted in an enclosing wiper housing such that the upper portion of the blade holder with heating element and metal cap or radiator, are positioned within the housing cavity and the lower portion of the blade holder and the wiper blade, face away from the housing, so that upon application of electricity to the heating element, heat is directed into the housing and also applied to the holder and indirectly to the wiper blade. The holder thus protects the wiper blade from direct application of heat and yet is of low cross-sectional profile and is of sufficient flexibility to follow curved windshield contours without early fatigue problems. The enclosing housing protects the radiator and heating element from wind chill and the radiator directs heat into said housing to warm same. The housing then reflects said heat back down around the holder and wiper blade and thus provides sufficient heat to minimize or prevent snow and ice build-up on housing and blade. In another embodiment of the invention, a flat flexible metal blade replaces the metal cap as radiator, to impart added flexibility to the wiper blade assembly.

Description

BACRGROUND OF T~E INVENTION

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Field of the Inventlon Thi~ lnvention relates to wina~hield ~lpers, partlcularly heated windshleld wipers.

The Prlor Art variou~ cold veather windshield wipers have been devlsea to prevent or miniml~e snow and lce bulldup thereon, whlch can impair the effectivenes~ of the w1per bladQs in clearing the wlnashleld of preclpltatlon, resulting ln reduced or blocke~
vislbllity tberethrough. In such prlor art heated wlpers, electrlcal heating elements have been lmbeded elther near or in the wiper blades, whlch proxlmity frequently has cau~ed damage to such blaaes ~hen sufflclQnt heat ~as applied to the heatlng elements to mQlt sno~ ana lce thereon ~.g. at about 180 F. or more. To prevent such overhea~lng, thQrmostats have been added to the hleatlng circuits o BOmQ prlor art heated wlpers wlth the lntentlon of inte~rruptlng tha 10w of current from auto battery to blade heatlng elements before such ~lade aamaglng tQmperatures ~ould be reached. ~owever, thesa DC operated thermostats have frequently fused and`blade overheatlng and damage occurred.
AttQmpts ~ere then maae ln ~he prior art to mount the wlper blade in a holder e.g. of plastlc and then mount the heating I element in ~uch holder to apply heat to the wlper blade indlrectly to prolong the llfe thereof. One e~ample of thls approach 18 USP 4tl94,261 to Parklnson (1980). As shown in Flgures l to 3 of thls reference, Parkinson provldes a rather thick holder or backing member that has a longitudinal groove on its undersiae for holdlng the wiper blade thereto and a longltudlnal groove on lts upper slde for holdlng a heatlng element thereln, whlch g~oove has a pair of upwaraly converglng Siae walls 38 ana 40, whlch together wlth wlre lnsulatlon 98, enclose the heatlng element 88 therein. Flns 46 and 48 of the holder are belleved to mount in a wlper houslng, which however 1~ not shown. ~o~ever, 8uch holder ln provlaing a ~uperstructure ~the converging slae walls 38 and 40) to enclose the above element has three problemsJ a) 1~ is too thlck and stlff to follo~ any slgnlflcant wlndshield curvature and thus ~ cannot sweep same clear of uatQr, snow, ice and the like.
Also, as the heatlng element in thls reference i~ totally enclo~ed in the holder~ b) excessive heat build-up thereln can ~` cause ~oftenlng o the plastlc and weakenlng and dlstortlon thereof~ Furthar, c) insufficlent heat rom the ~o-enclosed heaelng elèment can be tr~nsmittea to the ~lper houslng for preventlon of sno~ and ice build-up thereon. Accordlngly, there ~8 a need and market for a heated ~iper blade that i8 durable and that overcome~ thQ above prlor art shortcoalngs.
There has no~ been devQloped a heated wiper blade that has a holder that protects the ~iper blad~ from direct applicatlon of hQat therQto~ yRt 18 sufflclQntly fle~lblQ to follow curved ~indshleld contours withou~ early fatigue problems and also provldes sufflcient heat to the wlper houslng to mlnimize or prevent sno~ and lce bulldup thereon.

~ roadly the present lnventlon provldes a wlper blade assembly whlch lnclude~ a blade holder havlng an outslde portlon and an lnside portlon, a wlper blade mounted to the blade holder at the outslde portlon thereof and a flat electrlc heating . :

element mounted to t:he holder at the lnside portlon thereof.
The blade assembly further lncludes a radiator member surmounted on the holder at the ln~ide portion over the heatlnq element and In proxlmity there~o, the holaer being mounted in a wiper houslng such that the ~nsiae portion, the heatlng element and the radiator member face lnto the hou~ing ancl the out~lde portion and the wiper blade face away from the houQing, such that upon application of electrlclty to the heating element, heat is applied to the hou~ing and the holder and indirectly transmitted to the wiper blade to reduce ox prevent snow and ~ce buildup on the as~embly durlng operation thereof on a ~indshield .

nRIEF DBSCRIP~ION OF T~E DRAWINGS
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.~ The present invention will become apparent from the Eollowing-detailed Specificatlon and dra~lngs in whlchs Figure 1 1Y an elevation view, partly in schematic, of a portion of the heated wiper aæsembly embodying the present inventlon~
Flgure 2 i8 a` fragmentary perspective v`iew of component~ of the wiper assembly embodylng the invention of Flgure 1:
Figure 3 is a sectional elevation view of the lnventlon shown in Figure 1, ta~en on lines 3-3, looking in the directlon of the arrows, Figure 4 is a plan vlew partly ln sectlon, of a component of `
the blade assembly of the invention shown in Flgure 3 and Flgure 5 is an end sectional elevation view of the component ! f Flgure 4.
I Flgure 6 18 an elevation vlew, par tly in schematla, of a .
portion of another embodlment of the heated wlper a~sembly of the present inventionJ 1.
Figure 7 1~ a fragmentary perspec~ive view of components of - another embodiment of the wiper a~"sembly of the lnvention, and Figure 8 i8 a sectional elevation vlew of the lnventlon shown in Figure 6, taken on llnes 8-8, looklng ln the dlrectlon of the arrows.
', - DESCRIPTION OF PRE~"E~RE"D EMBODIMENT

Referring no~ ln more detall to the ara~ ngs, tho heated ~lper as-~embly of the lnvention 10, lncludQs ~iper blade 12, blade holder 14, flat heating element 16, heat conductive cap~l8 and ~iper housing members 20 and 22, a8 ~ho~m in Figures 1, 2 and 3. As indicated, the be~d 11 o~ the ~"~iper blade 12 18 inserted into the longituainal 810t 15 of the holdQr 14, wh~le the flat heating element 16 18 in8er~ea into the longitudinal groove 17 of the 'blade holder 14 a8 sho~n Q .9 . in Flgures 2 and 3. The heatlng element 16 i8 desirably a flat etched foll . lr"e~r"ber enclosatd ln ZZZZI dlelectric coatlng, to form a flat flexlble ribbon 16, as sho~n Q .9 . ln ~lgurQs 3 and 4. The heating ele~ent 16 is securQd ln placè ln the longltudlnal groove 17 of th~ blade holder 14, desirably by a h~at conductivQ longltudinal oap 1~, ~hlch 1~ d~lrably crlmp~d ~round tho uppor portlon of the blade holder 14 as sho~n ln Figure 2.
The so-crlmpQd bladQ holder 18 then mounted to plvotable ~t housing m~mber 20 at spaced support points 21, ~hlch housing 20 j 18 plvotably mounted ln turn, to the maln houslng 22 at pivot poin~ 19, as sho~n in Flgures 1 and 3, Accordlngly, th~ ~lper a8sembly of the present invention has a dlstinct advantagQ, as illustrated ln Flgure 3, ln the aentral locatlon of the heatlng element 16, backed by heat conductiv~
cap or radia,tor 18, ~hlch serves to direct heat through the pla"stic holder 14 and the flexlbl~ blade 12 and at the ~,,ame time, dlrect heat lnto the cavity 23 of the housing members 20 and 22, 80 as to heat such housing members and provide a .

.~ , ` 1327680 reflection of heat therefrom back down around the plastic holder 14 and flexible blade 12 80 as to proviae enough heat to sufflclently de-lce the flexible blade and the entlre wiper assembly 10, as indicated ln Figures 3 and 1 of the drawlngs.
9~ The radiator 18 made of metal of high heat conductlvlty and able to conduct heat rapldly from a heatlng element, so as to permlt the use of a higher wattage heatlng element than would other~lse be posslble wlthout damage to the element lt~elf, ad~acen~ plastlc holder or wiper blade.
Further, tha invention provldeq an encloslng wlper housing that extends around the heatlng element and radlator member, to - bloc~ and overcome the usual ~lnd-chlll factor on the j wlnashleld, ~hlch as noted above, a) permits the heat from the radlator to flo~ up into the enclosing houslng and heat lt to prevent snow and lce bulldup thereon and b) such housing then reflects the heat bac~ down around the wlper blade, further heating the blade and thus further preventlng the bulldup of ice and sno~ on such bladQ and assQmbly.
In another embodiment, tb~ heatea ~lper blade assembly of the lnventlon 30~ include~ ~iper blade 32, blade holder 34, flat heating element 36 wlth electric conductor 33, heat conductlve strip or radiator 38 and wlper houslng member8 40 and 42, as sho~n in Figures 6, 7 and 8. A~ indicated, the bead 31 of the wiper blade 32 is inserted into the longitudlnal slot 35 of the blade holder 34,-while th~ flat heating element 36 and heat `~ conductlve longitudlnal strlp 38, are inserted into the ! longltudlnal groove 37 of the blade holder 34, as shown e.g. in Figures 7 and 8.
~ The heating element 36 is desirably a flat etched foll ¦ member enclosed by a dlelectric coating, as described above.
j ~owever, instead of a heat conductive longitudlnal cap such as cap 18, ~hown in Figure 2 and described above, the radlator 38 is a flat heat conductive longltudinal strip as described above, 13276~0 which permits for greater flexibility of wiper blade assembly as it traverses a curved windshielf surface.
The so-assembled blade holder is then mounted to pivotable housing member 40, at spaced support points 41, which housing 40 is pivotably mounted in turn to the main housing 42 at pivot point 39, as shown in Figures 6 and 8.
This added embodiment of the present inveniton also has a distinct advantaqe, as illustrated in Figure 8, in the central location of the heating element 36, backed by heat conductive strip or radiator 38, which serves to direct heat through the holder 34 and the flexible blade 32 and at the same time, direct heat into the cavity 43 of the housing members 40 and 42, as shown by the ~eat flow arrows 45, 47 and 49, so as to heat such housing members and provide a reflection of heat therefrom back down around the holder 34 and flexible blade 32, so as to provide enough heat to sufficiently de-ice the flexible blade and tha entire wiper assembly 30, as indicated in ~igures 8 and 6 of the drawings. This eEbodiment further exhibits greater longitudinal flexibility as discussed above.
t The housing members desirably are of heat conductive material also, including metal, such as stainless steel, aluminum and brass.
Preferably the housing members are of metal, coated externally with j plastic, such as polytetrafluoroethylene (nTeflon~") for improved ~ interior heat retention and reflection characteristics and to r3 provide a non-stick surface resistant to the adhesion of ice and snow thereon. Other plastic coatings capable of withstanding high ¦ and low te~peratures can be used including flurocarbons and polyimides.
~ The blade holder radiator cap or strip, is desirably of heat-i conductive materials including metals, such as stainless steel, ~ aluminum and brass, which radiator overlies, fits over, '. X

is attached or is crimped to the blade holder.
The heating e!lement employed in the invention is desirably formed in a flexible ribbon and preferably is an etched foil heater enclosed in a dielectric coating, e.g. of silicon or other dielectric material (as opposed to e.g. a nichrome resistance wire of the prior art). such etched foil heating elements of the present invention are desirably of low wattage and have the proper resistance and conductivity to preferably allow a maximum element temperature of 70F., when a DC power source of 12 volts is applied thereto. Of course, greater element temperatures can be permitted at a lower or higher voltage than 12 volts, according to the parameters of the system being employed, within the scope of the prasent invention.
The electric conductor of the heating element of the invention iæ preferably s~aped in a slerpentine, zigzag, mesh or other open configuration to absorb expansion and contraction of the heating ele~ent during ~eating and cooling therQof. However, various other heating ele~ents can be em~loyed, whether of foil, wire or mesh type, which heating elements are desirably enclosed in a dielectric ocating in the form of a ~relatively flat or curved) fl~xible rikbon, within the SCOpQ of the present invention.
It is desirable t~at the resistance of a heating element be ad~usted so that the wattage output is relatively un1form along its length, whether the heating Qlements (and wiper blade length) be e~g. 13 inches, 18 inches or ao inchss long. A desirable watt density has besn found to be, within the present invention, from three to eight watts per square inch and preferably five to seven watts per square inch. In one example, the heating element of the wiper blad~ assembly of the present invention is made to have a tolerance of 5.~ to 6.5 ~att i ' ~

density, 80 a8 to accept the appllcation of 6 watts/sq. ln.
thereto for effectlve precip~tatlon removal from the wlndshleld.
A~ lndlcatea, the ob~ect 18, even al~trlbutlon of heat over the full length of the wlper blaae ana hous~ng ana requlrQs a heatlng element of unlform dlmensions to avold hot spots. The waetage of a heatlng element can bè varled by varying the dlmensions thereof and/or the composltion thereo, l.e. a change ` of alloy can mean a~change of resistance o~ the heatlng elQment and thus a change ln the watt denslty theeeof. It 18 thus lmportant to ad~ust the watt den~lty of the heatlng element ~ufflciently hlgh to melt snow and lce, but not so hlgh as to damage the heatlng element or the wlper bladQ a~sembly, includ~ng the ~iper blade. ThuQ the above watt density consiaerations are lmportant to a successful and durable wlper blade assembly as embodled ln the present lnventlon.
~ As lndicated ln Figur~ 1, the leaa ~lres to and from the -` heatlng element of the inventlon, exempll1ed by lead 25 ln F~gure 1, can be run ~ithin the ~lper houslng members and out the center of the ~lper assQmbly and down the ~iper support arm Inot shoun) to~thQ po~er sourcQ ln the vehiclQ, as shown in lgure 1. of coùrse, various other ~irlng hoo~ups and i configuratlons can be employed as deslred, ~lthln the sCopQ
of the present lnventlon. Lead ~lres advantageously have ; lnsulatlon stable at hlgh temperatures Q.g. ~Teflon~, where such j ~lres are enclose~d ln the heated area e.g. ln the houslng members 20 and 22 sho~n ln Figure 1.
The blade holder of the lnventlon i9 preferably relatlvely flat ln cross-sectlon for flexlblllty. Further, the blade holder of the inventlon de~irably (but not necassarlly) has a longltudlnal groove along lts lnslde portlon to recelve a heatng element and a longltudlnal slot along lts outslde portlon to recelve the ~lper blade. ~-_ g_ :
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The blaae holaer 13 de~1rably of a pla~tlc that has ~tr~ngth at hlgh and low temperatures and i~ weather-reslstant. The blade holder 18 advantageously made of durable plastic and 18 preferably rated at 275F. or more. For e~amples, the blade holder is deslrably o~ a stable plastlc such as a moalfled polyphenylene o~1de that i8 stable ~n a templerature range of - 40 F. to + 300 F., a modifled polyetherimlde, which is ` stable in a temperature range of - 400 F. to + 430 F. or other-~ stable plastics.
` The wlper blade employed in the present lnvention can have various cro~s-sectional shapes avallable, withln the scope of the invention and preferably utillzQs blades shaped as shown ln ~ Figures 2 ~ 3 and 7 ~ 8.
- Such blade ~8 aeslrably made of durable plastic or rubber or a combination thereof wlthin the scope of the inventlon. The blade can be ~ub~ected to high temperature~ e.g. 200-300 F and should not harden or crac~ at such temperatures. Also lt should be fle~ible at lo~ te~peratures such as at - 32 F and reslstant to various types of harsh environments encountered on the indshield of a~ehlclQ. A preferred material i8 ethylene-propylene-dlene ~PDM), a terpolymer elastomer, e.g.
~ ~Nordel TM ~, a plastic from E. I. duPone Co., Inc. Other i materlals can be used for ehe wiper blade of the lnvention, lncluding natural rubber, neoprene rubber, hydrocarbon elastomers or copolyester elastomers. Additionally, per the invention, one can employ a wiper blade of the above materials, having thermally conductivQ materlal added thereto, for improved j heat conductlvity Q.9. materlal such a8 carbon and varlous i metals.
The power sourcQ for the heat~d windshield wiper assembly of ~ the invention is desirably the battery of the motor vehicle, L e.g. a 6, 12 or 24 volt DC sourae, Pre~erably the wlper heating element is fused, switched and wired through the ignition circult rather than the wiper circult. This is because if the vehicle i8 parked ln snou and lce conditlons and the wlpers freeze to the wlnashlela, turnlng on tbe lgnltlon wlll apply current to the heatlng elements in the wlper assemblles, to warm the wlper blaaes and free them ~hlle the englne 18 warmlng up or shortly thereafter. The heater wattage i8 deslgned to llmlt the maximum heat generated to withln the safe llmlts of the hlgh temperature materlals usea ln the wlper a~sembly.

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Claims (2)

1. A heated windshield wiper blade assembly comprising a plastic wiper blade holder having a relatively shallow longitudinal groove formed in the upper surface thereof and a relatively deep longitudinal groove formed in the lower surface thereof, a wiper blade for contacting a windshield composed of material of relatively high flexibility having a bead portion conforming in shape to, and slightly smaller than said relatively deep longitudinal groove and disposed therein, a flat electrical heating element disposed in said relatively shallow groove and having its lower surface in continuous contact with a surface of said shallow groove, a heat conductive radiator also disposed in said shallow groove and having a lower surface in substantially continuous contact with the upper surface of said heating element, said blade holder being crimped about the edges of said radiator and said heating element to maintain them in place in supporting said blade holder but spaced therefrom to provide an interior cavity for the flow of heat about said blade holder, said housing members protecting said blade holder from wind-chill effects.

2. A heated windshield wiper blade assembly as defined in claim 1 wherein said housing members are substantially U-shaped having open ends facing said windshield whereby heat may flow from said interior cavity about said blade and toward said windshield.