Abstract:
A windshield washer system for an automotive vehicle includes a reservoir for holding windshield washer fluid, and an applicator system for furnishing washer fluid from the reservoir to an exterior surface of the vehicle. A heat transfer system recovers heat from a braking system of the vehicle and conveys the recovered heat to the washer fluid contained within the reservoir.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to a system for providing cleaning fluid to the exterior surface of a windshield or other vision unit installed in an automotive vehicle. As used herein, the term “vision unit” thus means a glazing panel of a vehicle, whether the panel is fixed or movable. 
     2. Disclosure Information 
     Automotive designers have utilized a variable plethora of systems for providing washer fluid or other cleaning liquids to the exterior surfaces of automotive windshields. Typically, automobiles used in areas subjected to sub-freezing temperatures will utilize washer fluid having freezing point depressants. Such depressants are all ultimately released to the atmosphere when the washer fluid is dispensed, and may participate in the formation of photochemical smog. The present inventive system allows the use of washer fluid having either no freezing point depressant chemical or a very low level of such additive, so as to minimize the release of any substance other than neat water to the environment. 
     U.S. Pat. No. 3,888,412 illustrates a system in which windshield washer fluid is heated by means of a heat exchanger which is itself warmed by circulating engine coolant. A system according to present invention is, however, suitable for use with vehicles either of the electrodrive variety in which no engine is used, or the hybrid style in which both an engine and an electrodrive system including a traction motor are employed. 
     SUMMARY OF INVENTION 
     A windshield washer system for an automotive vehicle includes a reservoir for holding windshield washer fluid, an applicator system for furnishing washer fluid from the reservoir to an exterior surface of a vehicle, and a heat transfer system for recovering heat from a braking system of the vehicle and for conveying the recovered heat to the washer fluid contained within the reservoir. 
     According to another aspect of the present invention, a braking system may comprise either a friction braking system including one or more brake calipers or expanding internal brakes, or it may comprise a regenerative braking system of an electrodrive vehicle having at least one traction motor, with the heat transfer system circulating a fluid through the traction motor to recover heat from the traction motor and to transfer the recovered heat to the windshield washer fluid reservoir. 
     According to another aspect of the present invention, the present system may further comprise a heat exchanger for transferring heat from engine coolant to washer fluid within the washer fluid reservoir. 
     According to another aspect of the present invention, a windshield washer system according to this invention may be employed in connection with a heated windshield. 
     According to another aspect of the present invention, a method for providing heated washer fluid to the windshield of an automotive vehicle may comprise the steps of maintaining a supply of washer fluid within the reservoir, recovering heat from a braking system of the vehicle, conveying the recovered heat to the washer fluid within the reservoir, and furnishing heated fluid from the reservoir to the windshield. 
     It is an advantage of the present invention that heat which would otherwise be rejected to the environment is used to reduce the need for anti-icing agents which could participate in the formation of photochemical smog. 
     It is a further advantage of the present invention that the windshield washer fluid may be heated so as to assist in de-icing the windshield when the engine of a hybrid vehicle is operating at an average power level that is insufficient to generate enough waste heat to warm the washer fluid and windshield. 
     Other advantages, as well as objects and features of the present invention, will become apparent to the reader of this specification. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a schematic representation of a windshield washer system according to the present invention. 
     FIG. 2 is a schematic representation of a traction motor having coolant passages for circulating a coolant fluid through the traction motor to recover heat from the traction motor according to an aspect of the present invention. 
     FIG. 3 is a representation of a brake caliper having a cooling passage disposed therein to recover heat from the caliper and to transfer the recovered heat to a windshield washer fluid reservoir. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIG. 1 windshield washer system  10  provides washer fluid  24  from a reservoir  12  to windshield  14 . Washer fluid is sprayed upon or furnished to windshield  14  by means of nozzle  18 . Then, wipers  16  further perform the cleaning function. Washer fluid  24 , as noted above, which may either be neat water or water with a detergent additive, or water with minimal amount of anti-freeze contained therein, is picked up from reservoir  12  by pump  26  and passed through line  22  to nozzle  18 . 
     Washer fluid  24  is kept above the freezing point by a heat transfer system including heat exchanger  20  mounted within reservoir  12 . Heat exchanger  20  is thus part of a heat transfer system for recovering heat from a braking system of a vehicle and for conveying recovered heat to washer fluid  24  contained within reservoir  12 . A coolant fluid such as oil, or an ethylene glycol/water mixture, or other type of heat transfer fluid known to those skilled in the art and suggested by this disclosure, is circulated by means of pump  38  through friction braking system  28 , through traction motor  32 , and even through engine  34 . Of course, if the vehicle is exclusively an electrodrive vehicle, engine  34  will not be utilized, and traction motor  32  and friction braking system  28  will therefore be the sole sources of heat for the present system. As a practical matter moreover, friction brakes may not be employed with the vehicle but some braking via traction motor  32  will generally be available and as a result, coolant would be circulated by means of pump  38  through traction motor  32  and into heat exchanger  20 , so as to warm the washer fluid  24  contained within reservoir  12 . A plurality of valves  36   b  is shown as controlling the flow of cooling fluid from friction brake system  28 , from traction motor  32  and from engine  34  through line  30  and pump  38  to heat exchanger  20 . Coolant then circulates via line  30  from heat exchanger  20  and through valves  36   a  to friction brakes  28 , traction motor  32 , and engine  34 . 
     FIG. 3 illustrates brake caliper  42 , which comprises part of friction braking system  28 , from which heat is recovered and thereby made available for conveyance to washer fluid  24  within reservoir  12 . Brake caliper  42  has cooling passage  44  formed therein. Coolant enters brake caliper cooling passage  44  through fitting  46  and is discharged through fitting  48 . Then, the fluid is circulated by means of pump  38  to heat exchanger  20 . 
     FIG. 2 illustrates traction motor assembly  32  having a motor  54 , which provides power to output shafts  52 . Motor  54  generates heat and this is true regardless of whether motor  54  is being operated as a motor or as an electrodynamic brake, or both. Coolant passage  56  is provided within motor  54 . This passage, which can be a coiled tube, an annulus or other type of passage known to those skilled in the art suggested by this disclosure, allows coolant which enters at coolant inlet  58  and is discharged at coolant outlet  62 , to circulate through motor  54 , thereby recovering heat from traction motor  54  and allowing transfer of recovered heat to fluid  24  within windshield washer reservoir  12 . 
     According to another aspect of the present invention, a method for providing heated washer fluid  24  to windshield  14  of an automotive vehicle includes the steps of maintaining a supply of washer fluid  24  within a washer fluid reservoir  12 , recovering heat from a braking system of the vehicle, which may be a friction braking system  28 , or a traction motor  32 , and conveying recovered heat by means of circulating pump  38  to heat exchanger  20  so as to provide heat to washer fluid  24  within reservoir  12 . The present method further includes the steps of heating fluid  24  within reservoir  12  with a heat exchanger  20  being provided with engine coolant circulated from engine  34 . Those skilled in the art will appreciate in view of this disclosure that although a single coolant circuit is shown having a single pump  38  in FIG. 1, separate heat exchangers  20  and separate coolant pumps and circuits could be used for each of the friction braking system, the traction motor and engine  34 . This is a matter of design choice commended to those wishing to employ a system according to the present invention. 
     In addition to the heating provided by a system according to the present invention, windshield  14  may be heated by means of a conventional coolant radiator heater, or by electric heating, or by other systems and devices known to those skilled in the art, who will also appreciate that the fluid line  22 , nozzle  18 , and pump  38  may either be heated by recirculating heated fluid  24  from reservoir  12 , or by electrical resistance heating or by other known means. 
     Although the present invention has been described in connection with particular embodiments thereof, it is to be understood that various modifications, alterations and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention. It is intended that the invention be limited only by the appended claims.