Note: Descriptions are shown in the official language in which they were submitted.
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ELECTRICALLY HEATED WIPER BLADE UTILIZING SPIRAL COILED RESISTOR
WIRE
FIELD OF THE INVENTION
This invention relates generally to heated wiper blade units. More
particularly this invention relates to a wiper blade heating element suitable for
incorporating into new or existing wiper blade.
BACKGROUND OF THE INVENTION
When a vehicle is operated during blizzard, snow, sleet, or other icy
conditions, precipitation may not be cleared away because the wiper blade becomes
encrusted with ice and snow build-up, whereupon the blade is pushed away from the
glass by said build-up. The vehicle defroster is incapable of heating the windshield
sufficiently to melt the ice forming on the blade and its associated mountings. When
ice builds upon the wiper blade, the wiper blade edge no longer has contact with the
windshield. Thus the blade cannot perform the intended function of wiping
precipitation from the windshield ultimately severally reducing visibility and safety.
There have been a variety of attempts to improve the wiping action of
a windshield wiper to clean the outer surface of a windshield in cold weather.
U.S. Patent No. 4,1 52,808 discloses a heating element 0.125" wide and
0.005" thick embedded in the sides of a frame adapted to receive a wiper blade. In
the upward direction, heat is transferred to the frame and linkage elements. In the
downward direction, heat is transferred from the element to the frame, from the frame
through a gap in the wiper body carrying the blade and finally down to the blade. In
the outward lateral direction, heat is transferred to the surrounding air and essentially
wasted. This indirect heating method is accordingly ineffective, inefficient and limits
the flexibility of the blade, thereby inhibiting the blade wiping action.
U.S. Patent No. 4,497,083 discloses a heated windshield wiper blade
having a resistance wire running along the length of the wiper arm, the blade carrier
and the wiper blade to heat the blade and the carrier when it is connected to a
vehicle's electrical system. The path through which the resistance wire travels and
its various connections is quite complex in order to provide the bla~de with heat.
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U.S. Patent No. 4,360,941, discloses a second, rather complex
windshield wiper assembly which incorporates a weather protective hood utilizingelectrical conductors affixed on the outer wall of the hood and other conductorsaffixed on the inner wall of the hood to heat the hood and frame to prevent the
accumulation of ice.
U.S. Patent No. 5,325,561 discloses an unnecessarily complex and
inefficient circuitry system. The heating element consists of straight wire which is
less than 1/3 of the width of the passageway. Thus the heating element can lie on the
passageway causing hot spots and decreasing efficiency and causing blade damage.The probability of a thin straight wire is more prone to breakage or failure.
The devices disclosed in the aforementioned patents leave much to be
desired from the standpoint of simplicity of construction, or are not sufficiently flexible
to be used with windshields of any desired lateral or longitudinal curvature; some
blade designs cause extremely localized heating placing undue stress on the material
of the blade. Some require specialized wiper blade frames andtor wiper arm
assemblies.
Accordingly, the present invention seeks to provide a simple, low cost
wiper blade assembly which is not fatigued by the repeated stresses of reciprocation
and is easy to replace and install.
Further, this invention seeks to provide flexible heated wiper blade
element suitable for incorporation into new or existing wiper assembles and able to
adapt to use on windshields having most any lateral or longitudinal curvature.
Still further, this invention seeks to provide a heated wiper blade which
permits the wiper blade to conform to the shape of the windshield under snow, sleet
or other icy conditions. Thus providing satisfactory wiping performance, while
simultaneously removing and keeping the wiper blade, frame and linkage free frominterference by ice and snow.
SUMMARY OF INVENTION
The present invention primarily seeks to provide a sufficiently heated
wiper blade adapted to be mounted on an existing or new wiper arm which sweeps
across a windshield or other surface to be wiped clear, such as rear window or
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headlight. The assembly includes an elongated wiper blade including heat resistant
resilient material and a blade carrier.
The invention in one broad aspect provides an electrically heated wiper
blade assembly comprising an elongated wiper blade adapted to be connected and
supported by a wiper blade carrier which carrier is adapted to be connected to awindshield wiper arm. The elongated wiper blade comprises an elongate, resilient,
flexible body having opposed first and second ends and having an elongated
passageway extending therethrough between the first and second ends thereof. A
flexible, spiral coiled heating element has a hollow, open interior and first and second
ends, the heating element being loosely received in the passageway of the wiper blade
such that the first and second ends of the heating element lie within the passageway.
First and second lead wires each having an end extending inside the wiper blade
passageway are electrically connected to respective first and second ends of theheating element within the passageway and waterproof sealant means sealingly close
the ends of the passageway of the wiper blade to form a closed heatable air space
therein, the first and second lead wires extending through respective sealed ends of
the wiper blade.
More particularly, the wiper blade includes a hollow horizontal
passageway extending the entire length of the wiper blade in which a spiral coiled
heating element is placed. Each end of the spiral coiled heating element terminates
at connectors located at ends of passageway within the wiper blade body. A live
stranded copper wire is securely crimped to first end connector of the spiral coiled
heating element and a stranded copper wire~is securely crimped to the second endconnector of the spiral coiled heating element. The passageway is sealed on each end
with a waterproof sealant.
Electric power is supplied to the spiral coiled heating element from the
vehicle's existing power supply in any currently known manner using a simple circuitry
system. The circuitry is basically a positive lead wire connected to the heatingelement. The spiral coiled heating element also connects to a ground wire. Simply
stated current passes through the heating element, the element heats and the heat is
conducted into the body of the wiper blade thereby heating the blade assembly.
Field testing of this invention has proven successful in providing
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satisfactory wiping performance while simultaneously removing and keeping the wiper
blade, frame and linkage free from interference by ice, sleet or snow with no apparent
deterioration of the blade, wiping performance, or heating element. Secondarily field
testing also indicates that road film in all weather is removed more effectively and
thoroughly if the blade squeegee is heated when used in conjunction with a windshield
solvent cleaner.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is an exploded fragmentary view illustrating the live wire
making electrical contact with the spiral coiled heating element within connector and
sealant.
FIGURE 2 details an enlarged cross sectional view of wiper blade
illustrating spiral coiled heating element within the passageway.
FIGURE 3 illustrates an enlarged perspective view of an exposed portion
of wiper blade unit exposing the passageway and its content.
FIGURE 4 illustrates position of lead and ground wires upon the support
spine beneath the wiper blade carrier clips, after which the wires enter the
passageway at wiper blade assembly ends.
FIGURE 5 is a schematic of heating element circuitry.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in greater detail to the various figures of the drawings
wherein like reference characters refer to like parts. There is shown in FIGURE 4 a
heated wiper blade. The complete system basically comprises a wiper blade assembly
60 fitted onto the blade carrier 90. As shown in FIGURES 1, 2 and 3 passing through
the wiper blade assembly 60 is a spiral coiled heating element 20 which heats the
wiper blade assembly 60 and parts of the lower blade carrier 90.
The wiper blade carrier 90 is connected to a wiper arm (not shown) and
motor (not shown) which causes the wiper blade edge 40 to squeegee across the
windshield or area to be wiped clear in a conventional manner.
In FIGURE 4, the elongated support spine 45 is positioned upon the wiper
blade assembly 60. The support spine 45 is part of the wiper blade assembly 60 that
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slides through the wiper assembly head clips 35 of wiper blade carrier 90 when
assembling or removing wiper blade assembly 60.
The support spine 45 material is of a hard resilient plastic or metal as to
prevent clips 35 of wiper blade carrier 90 from pulling free of wiper blade assembly
60. Live wire 10 and ground wire 30 are held upon the support spine 45 by
positioning said wires under wiper blade assembly clips 35.
In FIGURE 2 a cross section of heated wiper blade assembly 60 connects
to wiper blade top head 65 by a flexible integral hinge 55 constructed as one unit.
Wiper blade body 60 contains passageway 80. The passageway serves to entomb
spiral coiled heating element 20.
The wiper blade assembly 60 comprises an elongated extrusion of a
flexible resilient material which can withstand temperatures in excess of 200~F. Such
materials may be neoprene or silicone rubbers, but other suitable materials may be
used. The blade assembly 60 includes a hollow horizontal passageway 80 extendingthe entire length of the wiper blade assembly 60. As shown in FIGURE 3 the
passageway 80 extends from one end to the other end of the wiper blade assembly
60.
The passageway 80 serves to receive the elongated spiral coiled heating
element 20 which consists of resistance wire such as Nichrome. The passageway 80also serves as a means for inserting the spiral coiled heating element 20 into the body
of the wiper blade assembly 60.
Live wire 10 and ground wire 30 consist of stranded copper wire.
The spiral coiled heating element 20 is positioned within the passageway
along with identical end connectors 70 and 75, a live wire 10 and a ground wire 30
are securely crimped to end connectors 70 and 75 of the spiral coiled heating element
20.
FIGURES 1 and 3 show the passageway 80 sealed on both ends injected
inward approximately 3/8 inch with a waterproof sealant 50 such as DAPTM
manufactured by Dow Chemical. The waterproof sealant 50 seals the passageway
80 so as to prevent movement of spiral coiled heating element 20, live wire 10,
ground wire 30 and end connectors 70 and 75, at the ends of the passageway 80 and
also allows for an airtight passageway 80 with spiral coiled heating element 20 to be
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moisture free. The spiraiing of the spiral coiled heating element 20 allows the wiper
blade assembly 60 to remain sufficiently flexible to be used with windshields of any
lateral or longitudinal curvature. The spiral coiled heating element 20 has enough
spring elasticity as to not ailow it to suffer fatigue because of the stresses of the
normal wiper operation.
The spiral coiled heating element 20 with an outside diameter of
approximately 5/64 (0.078) inches and approximately ten coils per inch is positioned
between connectors 70 and 75. Passageway 80 is about 1/8 (0.125) inches in
diameter.
For example, the process of coiling sixty-six inches resistance wire of
0.0226 diameter inches with a total resistance of 7.25 OHMS t1.272 OHMS per foot)
and a draw of 1.55 AMPS within the confines of a twenty inch blade provides
sufficient even heating throughout the blade length in all directions including
downward to wiper blade edge 40, outward to and including sealant 50 and upward
into most lower parts of wiper blade carrier 90.
The length of Nichrome wire used during wiper blade manufacturing
changes according to blade length. Total OHMS of resistance and amperage draw
changes are necessary for each specified blade length to maintain the proper heating
level of 100~F. - 130~F. However different gauge resistance wire can also be used
with its own specific calculation to meet respective heating needs.
Electric power is supplied to the spiral coiled heating element 20 from the
vehicles existing power supply. The heating assembly may be connected to the
electrical system of the vehicle in any known manner which will direct electrical
current into and through the spiral coiled heating element 20.
FIGURE 5 shows a simple wiring circuitry schematic. Power to live wire
10 can be provided by the live wire of another cold weather accessory such as a
heated mirror. While driving during inclement weather a heated mirror and heatedwiper blade assembly 60 can be used simultaneously. Thereby utilizing the same
on-off switch, light indicator and some of the same wiring.
Another source of power for live wire 10 is the cigarette lighter
receptacle using an accessory plug adapter (not shown); or the live wire 10 could be
wired directly to the vehicle power source using a separate on-off switch (not shown)
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with or without a temperature sensor thermostat (not shown) located away from the
heated wiper blade to monitor the outside air temperature and would automatically
turn on when outside air temperature drops below 35~F. and would shut off when
outside air temperature rises above 35~F. This air temperature on-off switch is wired
directly into ignition switch.
FIGURE 5 illustrates the simplicity of the heating blade circuitry: a
positive live wire 10 leads to a fuse holder 100 containing a 2 AMP fuse, leads to
spiral coiled heating element 20 to ground wire 30.
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