Abstract:
A nozzle assembly ( 18 ) for a windshield washer system or the like provides an elongate heater element ( 30 ) that can extend along a supply tube connected to the washer nozzle ( 20 ) to better transfer heat energy into the washer fluid and the nozzle for preventing nozzle clogging caused by low temperatures.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional applications provisional 62/101,041 filed on Jan. 8, 2015 and hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to vehicular window washing systems and, in particular, to a vehicle window washing systems providing a nozzle heater. 
       BACKGROUND OF THE INVENTION 
       [0003]    Window washing systems, for example, for use on the windshield, may work in conjunction with vehicle windshield wipers to spray a cleaning fluid on the windshield during activation of the wipers. During winter months, an anti-freeze material such as alcohol may be added to the washing fluid to keep it from freezing. During those times, even when alcohol has been added to the washing fluid, the washing fluid nozzles, positioned in the wind stream and exposed to environmental moisture, may freeze over becoming inoperative at times when they are needed. 
         [0004]    It is known to place ceramic, positive temperature coefficient (PTC) heating elements in the nozzle assembly to provide for localized heating of the nozzles that can prevent icing. The disk-shape ceramic element is normally potted with a resin material to protect it from humidity and to fill the gap between the nozzle and the rigid PTC heater. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a heating element that better distributes heat to the nozzle and connecting tubing thereby increasing the contact area and decreasing the intervening thermal resistance to provide more efficient nozzle heating. The heating element may be a flexible strip of PTC material or PTC-coated material with applied electrodes that can flex so that the strip may have improved contact the nozzle. Alternatively, the heating element may be a PCT material applied directly on the nozzle and connecting tubing. By reducing the distance between the liquid and the heater and the thermal mass of the heater/nozzle system, heat may be more quickly applied to the nozzle for rapid availability as soon as the vehicle is started and for reduced heat loss and power consumption while in use. 
         [0006]    In one embodiment, the invention provides a vehicular washer nozzle assembly having a housing adapted to attach to a vehicle adjacent to a window and a standpipe extending along an axis within the housing to terminate at a nozzle to direct a stream of liquid from the nozzle toward the window when the housing is attached to the vehicle. An elongate electrical heater element extends along a length of the standpipe to heat the same. 
         [0007]    It is thus a feature of at least one embodiment of the invention to provide for a distributed rather than localized heat source greatly improving heat conduction into critical nozzle areas. In particular the invention may direct more heat into the nozzle and tubing (and possibly included washer fluid) and less heat into the material of the housing through its distributed and conformal nature. 
         [0008]    The elongate electrical heater may be in contact with the majority of the length of the standpipe within the housing. 
         [0009]    It is thus a feature of at least one embodiment of the invention to minimize the total thermal resistance between the standpipe and the heater by maximizing an area of contact. 
         [0010]    The elongate electrical heater may provide electrodes extending along substantially the entire length of the heater strip within the housing adapted to communicate with a source of electrical power in the vehicle and separated by a resistive heating material. 
         [0011]    It is thus a feature of at least one embodiment of the invention to greatly increase the heater area thereby improving distribution of heat through extended electrode geometry. 
         [0012]    The electrodes may each provide for a comb structure presenting interdigitated comb fingers. 
         [0013]    It is thus a feature of at least one embodiment of the invention to provide a large uniform heating area by using a highly distributed electrode structure. 
         [0014]    The resistive heating element may be a polymer. 
         [0015]    It is thus a feature of at least one embodiment of the invention to provide a robust heater element resistant to vibration and moisture. 
         [0016]    The resistive heating element may be a positive temperature coefficient heating element. 
         [0017]    It is thus a feature of at least one embodiment of the invention to eliminate the need for separate thermal sensing inside the housing for temperature control during a wide range of ambient temperatures. It is a further feature of at least one embodiment of the invention to provide for rapid heating without concern for hot spots or heater damage that might otherwise attend to high currents. The positive temperature control material naturally evens out heat and prevents hot spots. 
         [0018]    The standpipe may be curved and the elongate electrical heater may curve to follow the standpipe. 
         [0019]    It is thus a feature of at least one embodiment of the invention to provide a system that may work with curved fluid conduits desirable for particular vehicular applications. 
         [0020]    The resistive heating element may be flexible to be curved during manufacture to follow the standpipe. 
         [0021]    It is thus a feature of at least one embodiment of the invention allow improved conformance of the heater to an irregular nozzle and standpipe and improved manufacturability that may result from being able to deform the heater element during assembly. 
         [0022]    The flexible heater strip may be exposed outside the housing to expose the electrodes to connection. 
         [0023]    It is thus a feature of at least one embodiment of the invention to eliminate the need for separate wiring to terminals or the like. 
         [0024]    The vehicular washer nozzle assembly may include a potting material for holding the elongate heater element in proximity with the standpipe. 
         [0025]    It is thus a feature of at least one embodiment of the invention to provide a manufacturing technique for holding and contacting the heater element to an arbitrary nozzle and standpipe. 
         [0026]    The standpipe may join with a feeder tube in a T-connection and the elongate electrical heater may include side arms that conform to the feeder to extend in opposite directions from the standpipe. 
         [0027]    It is thus a feature of at least one embodiment of the invention provide a heater that can be flexibly designed to follow fluid lines in two dimensions. 
         [0028]    The side arms maybe flexible to be curved for insertion into the housing and then to extend along the feeder tube. 
         [0029]    It is thus a feature of at least one embodiment of the invention to allow for a heater to follow a complex tubing geometry. 
         [0030]    The housing may be constructed a polymer material and the potting material has a lower thermal resistance than the housing. 
         [0031]    It is thus a feature of at least one embodiment of the invention to assist in transferring heat from the heater element to the standpipe and nozzle and/or feeder tube using a conductive space filler. 
         [0032]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]      FIG. 1  is a perspective view of an automobile windshield from outside of the automobile showing the location of typical windshield washer nozzles such as may become blocked with ice; 
           [0034]      FIG. 2  is a front elevational view of a nozzle of the present invention using a conformal flexible PTC heater strip inserted into a housing holding the nozzle; 
           [0035]      FIG. 3  a front elevational view of the PCT heater strip for installation into a nozzle housing; 
           [0036]      FIG. 4  is a cross-section along lines  4 - 4  of  FIG. 2  showing flexible conformance of the PCT heater strip with the nozzle; and 
           [0037]      FIG. 5  is a perspective rear view of an alternative embodiment with the PTC material and electrodes printed directly on the nozzle structure. 
       
    
    
       [0038]    The term “along an axis” refers to a general orientation and should not be understood to require that a component extending along the axis be straight but only that it have a substantial component of extension along the axis. 
         [0039]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]    Referring now to  FIG. 1 , a vehicle  10  may provide for a window  12  such as a windshield positioned behind and above washer system nozzles  14  oriented to provide a spray  16  of washer fluid on the window  12  for cleaning with the wiper blades  18  as is generally understood in the art. Analogously, but not shown, the nozzles  14  may be positioned adjacent to other windows  12  including headlight lenses, cameras, and windows over radar, ultrasound or the like. 
         [0041]    Referring now also to  FIG. 2 , each nozzle  14  may provide for nozzle  20  directing a stream of washer fluid  21  toward the adjacent window  12  and typically rear facing with respect to the direction of the forward vehicle. The nozzle  20  may communicate by standpipe  22  extending generally along an axis  19  with a feeder tube  24 , the latter attached to flexible washer fluid hoses  25  leading from a washer pump  27  and fluid reservoir  29  and/or to a downstream nozzle  14 . Although the standpipe  22  extends generally along an axis  19  it may curve as it connects to the nozzle  20  to direct the nozzle  20  in a desired direction. In one embodiment, the standpipe  22  may join in a T-connection to a center of the feeder tube  24  which extends horizontally and perpendicular to the upstanding standpipe  22  to terminate an opposed barb connection  31 . 
         [0042]    The standpipe  22  and feeder tube  24  may be premolded, for example, by injection molding, and contained within a housing  26  that serves to attach the nozzle  14  to the structure of the vehicle  10 . As so contained, the nozzle  20  extends from an upper portion of the housing  26  and the feeder tube  24  extends outward from either side of the housing  26 . The housing  26 , the standpipe  22 , and the feeder tube  24  will typically be molded of a thermoplastic material of low heat conduction. 
         [0043]    A conforming heater strip  30  may provide for a connector end  32  extending from the housing  26  having electrodes  42   a  and  42   b  across which a heater voltage source  34  (such as 12 volts) may be applied during use. The electrodes  42   a  and  42   b  may extend along the length of the heater strip  30  on opposite sides of the heater strip and may include projecting comb fingers  43  such that comb fingers of the opposite electrodes  42   a  and  42   b  are interdigitated maximizing a current throughput in a uniform distributed fashion through a surrounding heating material. 
         [0044]    Referring also to  FIG. 4 , the heater strip  30  may extend into the housing  26  and may closely underlie the nozzle  20  of the standpipe  22  and portions of the feeder tube  24  to be retained thereagainst by a structure of the housing  26  or an overmolding, molded structure of the housing  26 , or potting compound  36 . Ideally, the heater strip  30  is in contact with the standpipe  22  over the majority of its length. The potting compound  36  may provide for enhanced heat conduction when compared to the material of the housing  26 , for example, by the inclusion of thermally conductive particles. The heater strip  30  may flex to follow a curved path of the standpipe  22  and nozzle  20  and for that reason may reduce any gap between the heater strip  30  and the standpipe  22  and nozzle  20  and the corresponding thermal resistance caused by that gap. 
         [0045]    Referring to  FIG. 3 , in this regard, the heater strip  30  may be a simple rectangular flexible strip of sufficient length to extend into the housing  26  along the length of the standpipe  22  and be closely proximate to the standpipe  22 . In addition, the heater strip  30  may include side wings  38  positioned to extend laterally slightly along the feeder tube  24  within the housing  26  to preheat liquid therein. In this regard, the side wings  38 , being flexible, may be curved slightly to fit into the housing  26  and then to expand along the feeder tube  24  and even to curve slightly about the feeder tube  24  encouraged by the housing structure or the like to more closely conform to the feeder tube  24 . Ideally the side wings  38  are in close contact with the feeder tube  24  over the majority of its length within the housing 
         [0046]    Generally, the heater strip  30  may include a sheet polymer material  40  providing a flexible substrate on which is applied interdigitated electrodes  42   a  and  42   b  receiving the voltage source  34  as shown in  FIG. 2 . The polymer material  40  may provide for a high resistance conductance (greater than that of the electrodes  42 ) to provide a resistive heater element with a positive temperature coefficient to provide for self-regulating temperature control. As is understood in the art, positive temperature coefficient materials dramatically increase their resistance with increased temperature thus providing improved temperature regulation by decreasing current flow (and hence heating) as their temperature rises. 
         [0047]    The interdigitated electrodes  42   a  and  42   b  are each connected to a different voltage polarity to apply a voltage across the polymer material  40  (for example, 12 volts DC) promoting current flow through the polymer material  40  generally along the plane of its extent suitable for heating in this application. Electrodes  42  may be, for example, screenprinted using conductive metallic inks or vapor-deposited, for example, of silver, aluminum or the like or applied as a thin decal or etched from an adhered film using integrated circuit techniques or a variety of other manufacturing processes. 
         [0048]    Positive temperature coefficient (PTC) heaters, suitable for the flexible heater strip  30  of the present invention, are also disclosed in U.S. Pat. Nos. 4,857,711 and 4,931,627 to Leslie M. Watts hereby incorporated in their entirety by reference. 
         [0049]    In one embodiment, the flexible heater strip  30  may be constructed of a flexible insulating sheet of insulating polymer material with a resistive positive temperature coefficient conductor applied to the upper surface to form a resistive or ohmic heating element. Alternatively, conventional resistive material may be used for the polymer material  40  or applied to the polymer material  40  and a constant current may be applied by the electrodes  42  across this material in “open loop” fashion or is controlled by a separate thermal sensor such as thermistor, thermostat or the like. 
         [0050]    Referring now to  FIG. 5 , in an alternative embodiment, the nozzle  20 , standpipe  22  and feeder tube  24  may be an integrated structure, for example, a single injection molded part providing an outer surface  44 . The flexible heater strip  30  may then be insertion molded as part of this molded component. Alternatively, the outer surface  44  may be coated with a positive temperature coefficient resistive material or standard resistive material and electrodes  42  applied to that coating which may then attach to conductive leads  50 , the latter of which may connect to the voltage source  34 . The interdigitated structure of the resistive material may be formed by a printing process or by a laser or other etching of a thin film of resistive material uniformly applied and then removed to produce the interdigitated fingers. Alternatively, the body of the nozzle  20 , standpipe  22 , and feeder tube  24  may be comprised of a PTC polymer material either in its entirety or in a two-step molding process in which the PTC material is applied over a non PTC polymer core and electrodes applied across the PTC material. 
         [0051]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. When an element is indicated to extend along an axis this is intended to indicate the general orientation of the element for clarity and does not limit the element to a straight extension, only extension that has component along the axis. 
         [0052]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0053]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.