Abstract:
A windshield heater for heating the bottom section of a vehicle windshield includes a heating element located proximate the windshield selectively energized by direct current from the electrical circuit of the vehicle. The heater may be a heating element directly adhered to the windshield. Alternatively, the heater may include a sleeve enveloping the length of the heating element and a corresponding length of compressible material to lodge the heater between the windshield and the adjacent section of a dashboard to place the heating element proximate the windshield.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electrically energized heaters for vehicular windshields and, more particularly, to a heater for heating the lower edge of a windshield. 
     2. Description of Related Prior Art 
     During the winter, vehicles, whether land based watercraft or aircraft, are subject to snowfall and icing. This is a particular problem when visibility through the front windshield is obscured or otherwise compromised by snow and icing. For decades, this problem has been addressed by hot air defrosters urging a flow of air against the interior surface of the windshield to heat the windshield. The windshields are usually of glass and as glass is a poor conductor of heat, a significant period of time elapses before the snow and/or ice adjacent the exterior surface of the windshield melts. Windshield wipers, wiping the exterior surface of a windshield generally provide the area of contact relatively clear of snow and ice. 
     Presently used defrosters which emit air from one or more slots or vents in the dashboard of a vehicle generally direct the heated air against the windshield upwardly from a location significantly above the bottom edge of the windshield. Similarly, windshield wipers generally do not produce a wiping action against the exterior surface of the windshield close to the bottom edge of the windshield. Under severe conditions when a vehicle may have not been used for a period of time, sufficient ice may have formed along the bottom of a windshield to encase the windshield wipers and prevent their operation. 
     The lack of visibility along the lower part of a vehicular windshield compromises the view of the operator of the vehicle. Such compromise is a distinct safety hazard which is exacerbated during periods of severe inclement weather, whether by heavy snowfall or very low temperatures causing rapid and sustained icing. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a heater for heating the lower part of a vehicular windshield to cause melting of any snow or ice formed thereupon. A heating element may be directly adhered to the bottom interior surface of the windshield to transmit heat by conduction to the windshield to cause warming of this section of the windshield and the melting of any ice or snow on the corresponding exterior surface of the windshield. Alternatively, the heating element, in combination with compressible material, may be enveloped within a sleeve positioned between the lower part of the windshield and an adjacent surface of a dashboard extending from the windshield. Electric power for the heating elements may be temporarily or permanently provided by the electrical system of the vehicle. 
     It is therefore a primary object of the present invention to provide a heater for heating the lower part of a vehicular windshield. 
     Another object of the present invention is to provide a heater that may be temporarily secured adjacent the lower edge of a vehicular windshield. 
     Still another object of the present invention is to provide a heater adhered to the inside surface of the lower edge of a windshield. 
     Yet another object of the present invention is to provide a heater lodged in place between a windshield and the adjacent dashboard of a vehicle to maintain a heating element proximate the inside of the windshield. 
     A further object of the present invention is to provide a windshield heater for melting ice and snow on the lower outside surface of a vehicular windshield with a heater located adjacent the inside surface of the windshield. 
     A still further object of the present invention is to provide a windshield heater selectively connectable to the electrical system of a vehicle. 
     A yet further object of the present invention is to provide a method for melting snow and ice along the lower edge of a vehicular windshield. 
     These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be described with greater specificity and clarity with reference to the following drawings, in which: 
         FIG. 1  illustrates the windshield of a conventional land based vehicle having the present invention mounted between the windshield and the adjacent dashboard; 
         FIG. 2  illustrates an embodiment of the windshield heater; 
         FIG. 3  illustrates a partial cross section of the windshield heater mounted between the windshield and the dashboard of a vehicle; 
         FIG. 4  is a cross sectional view taken along lines  4 - 4 , as shown in  FIG. 2 ; 
         FIG. 5  illustrates details attendant the junction of two heating elements of the heater shown in  FIG. 2 ; 
         FIG. 6  illustrates a protected covering disposed at the junction between two heating elements shown in  FIG. 5 ; 
         FIG. 7  is a partial cutaway view illustrating components of the heater; 
         FIG. 8  illustrates a truck having a windshield with minimal slope and a windshield heater located thereon; 
         FIG. 9  is a representative cross sectional view illustrating the location of the heater with respect to the windshield and dashboard of a truck; 
         FIG. 10  illustrates an embodiment of the present invention particularly suitable for use with the windshield of a truck; and 
         FIG. 11  illustrates further details of the embodiment of the heater shown in  FIG. 10 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , there is illustrated in dashed lines a representative automobile  10 , which may be a sedan. It includes a conventional windshield  12  that may be more or less curved laterally and have a greater or lesser slant rearwardly. Dashboard  14  includes vents  16  and  18  to channel hot air onto the inside surface of the windshield for defrosting purposes. While the present invention is primarily directed to use in a land-based vehicle, such as automobile  10  or a truck  80  (see  FIG. 8 ), it could just as well be used in an aircraft or in a watercraft. That is, most aircraft and many watercraft include a windshield and a dashboard extending therefrom having vents incorporated therein for defrosting purposes. 
     Windshield heater  20  for the sedan shown in  FIG. 1  is located at the junction between windshield  12  and dashboard  14  generally in contact with the interior surface of the windshield. Conductors  22  engage the heater with a source of electric power in automobile  10 , which may be a conventional socket for a cigarette lighter. Upon energisation of the windshield heater, it will transmit by conduction heat to the interior surface of the windshield. This heat will migrate through the windshield and warm the outside surface. Any snow or ice adjacent this warmed surface will melt. 
     Referring jointly to  FIGS. 2 and 4 , certain features attendant windshield heater  20  will be described. The heater includes left and right sections,  24 ,  26 , respectively, extending laterally from junction  28 . Conductors  22  extend from the junction and may terminate in plug  30  adapted for insertion into a conventional cigarette lighter socket. Thus, control of operation of the windshield heater is primarily a function of whether plug  30  is or is not in engagement with the cigarette lighter socket; however, a switch may be incorporated. Each of left and right sections  24 ,  26  include a sleeve  32  generally triangular cross section. A heating element  34  is located adjacent side  36  of the sleeve and maintained thereagainst by compressible material  38  having a generally triangular cross section. 
     Referring to  FIG. 3 , there is illustrated in cross section the windshield heater mounted in place. For most passenger cars, windshield  12  slopes rearwardly at a fairly large angle. Dashboard  14  extends forwardly to the base of the windshield. Vent  18  discharges heated air, represented by a plurality of arrows  40  directed generally upwardly from the vent. A windshield wiper  42 , when at rest, is generally horizontally orientated and located proximate the lower edge of windshield  12 , as illustrated. By inspection, the flow of heated air, represented by arrows  40 , is upwardly toward the windshield and the heated air flows upwardly along the inside surface of the windshield. The lower part of the windshield is generally not directly heated by the outflowing heated air. Thus, any heating along the lower edge of the windshield occurs only through migration of heat downwardly through the windshield. As glass is generally a poor conductor of thermal energy, there is little warming along the lower edge of the windshield. Moreover, the motion of conventional windshield wipers generally does not extend to the lower edge of the windshield and the resulting non-wiped area of the windshield is subject to accumulation of snow and ice. Furthermore, if the automobile has been standing for some time during a snowfall and subsequent icing, the windshield wipers may become encased in ice and immovable by the windshield wiper motor. 
     By lodging windshield heater  20  at the apex between dashboard  14  and windshield  12 , as illustrated in  FIG. 3 , contact with the lower inside surface of the windshield is established. By urging the heater toward the apex, compressible material  38  will become compressed, as illustrated, to firmly lodge the windshield heater in place and maintain side  36  of the enveloping sleeve adjacent the windshield to locate heating element  34  proximate the windshield. 
     Upon energizing the windshield heater, heating element  34  will heat by conduction the lower edge and section of the windshield. This heat will migrate through the windshield and heat the exterior surface resulting in melting of any snow or ice that may be lodged thereupon. This heating will also melt the ice that may have captured windshield wiper  32  to free it and thereafter permit it to perform its function. 
     Referring jointly to  FIGS. 5 and 6 , details of windshield heater  20  will be described. Left and right sections  24 ,  26  are essentially mirror images of one another. Each section includes compressible material  38  supporting heating element  34 , both of which are enveloped within sleeve  32 . Each of heating elements  34  includes the one or more wires which are thermally responsive to electric current transmitted thereto. That is, as electric current is applied, the temperature of the wire will rise. For example, wire having such characteristic and often used as a heating element is known as nichrome wire. The wire or wires may be embedded in a serpentine configuration within a strip  52  of material which, for example, may be man-made. Various other support structures for wires  50  may be employed that will conduct heat and maintain the wires in their appropriate orientation. Wire  50  is electrically connected to a pair of conductors  54 ,  56 . Similar conductors  58 ,  60  are electrically connected to wires  50  embedded in strip  52  in right section  26 . Conductors  54  and  58  are electrically connected to one another in junction  62  and conductors  56  and  60  are also connected to one another within junction  62 . Thereby, the two heating elements are electrically connected in parallel. A pair of conductors  64 ,  66  correspond with conductor  22  shown in  FIG. 1 . 
       FIG. 6  primarily illustrates a shield  70  extending about the junction between left and right sections  24 ,  26  of windshield heater  20  for purposes of protecting the electrical connections therebetween. This shield extends about the enclosed ends of the left and right sections (as shown in  FIG. 2 ) and includes two flat sections  72 ,  74  joined to one another for supporting junction  62  and conductors  64 ,  66  extending therefrom to protect the enclosed conductors and prevent damage to and displacement thereof. 
       FIG. 7  illustrates outer end  76  of heating element  34  in left section  26 . Compressible material  38  may be terminated proximate end  36 , as illustrated, to fit the width of the windshield and dashboard of the land based vehicle, aircraft or watercraft wherein the windshield heater is used. The terminal end of right section  24  is similarly configured. 
     Referring to  FIG. 8 , there is shown a conventional truck  80  which may be of the type generally know as an 18-wheeler. Trucks of this type generally include split windshields  82 ,  84  separated by a bar  86 . These windshields are generally near vertical. Dashboard  88  may include two or more vents  90 ,  92  for directing heated air onto the interior surfaces of the windshields. As described above, the lower section of each windshield generally is not subjected to the defrosting heated air from the vents. Consequently, snow and ice will tend to form and collect along the lower edges of the windshield. Furthermore, windshield wipers  94 ,  96  travel through their arc beginning at a location above the bottom of the windshield. This creates a serious problem of ice and snow collecting along the bottom of each windshield and interferes with a downward line of sight for the driver. 
     As illustrated in  FIG. 9 , vent  90  disposed in dash  88 , directs heated air, represented by arrow  98 , to the middle and upper part of windshield  84 . The lower part of the windshield, as represented by the location of wiper  94 , generally does not receive heated air for purposes of defrosting the windshield and melting the snow and ice at the lower part of the windshield. By locating a heating element  100  adjacent the lower part of windshield  84 , this part of the windshield will be warmed and any snow or ice collecting on the outside thereof will melt. Such melting will also release the windshield wipers ( 84 ) preventing encrusting snow or ice. 
       FIGS. 10 and 11  illustrate a heating element  100  usable with a truck of the type depicted in  FIG. 8 . The heating element includes a left section  102  and a right section  104 . Section  102  includes a heating element  106  formed by a strip  108  of man-made material encasing one or more wires  110 , which wires are thermally responsive to electric current flowing therethrough. Section  104  includes a similar strip  112  having one or more wires  114  embedded therein, which wires are thermally responsive to electric current passing therethrough. Wires  104 ,  112  may be embedded in a serpentine configuration. To secure sections  102 ,  104  a contact adhesive  116  is disposed on one side of strip  112 . A similar contact adhesive (not shown) is disposed on one side of section  102 . Prior to use, this adhesive is protected by a peel strip  118  as shown with respect to section  104 . 
     Electrical conductors  120 ,  122  interconnect wire  110  with respective posts  124 ,  126  mounted on a bracket  128 . Similarly, electrical conductors  130 ,  132  interconnect with the ends of wire  114  within strip  112  and are attached to posts  134 ,  136  mounted on bracket  138 . Electrical conductors  140 ,  142  extend from posts  124 ,  126  to posts  134 ,  136 , respectively. A further pair of conductors  144 ,  146  extend from posts  134 ,  136  to a conventional plug  148  for engagement with a conventional cigarette lighter socket in truck  80 . Thereby, the wires within sections  102 ,  104  are connected in parallel and receive electrical power from the truck. 
     As representatively illustrated in  FIG. 10 , brackets  128 ,  138  may be attached to their respective windshields by contact adhesive  150  disposed on flanges  152 ,  154  of bracket  138  and on flanges  156  and  158  of bracket  128 . Prior to use, peel strips  160  may be used to protect the underlying contact adhesive. By use of contact adhesive, the sections and brackets of heater  100  are readily detachably attached to the split windshield of a truck, as depicted in  FIG. 9 .