Abstract:
A windshield wiper includes a wiper arm, which is driven via a drive shaft and to which a wiper blade is pivotably connected, in which at least one spray nozzle ( 10 ) is disposed on a pivotable part ( 14 ), the spray nozzle being composed of a plurality of parts and its housing ( 16 ) communicating disconnectably via a water line ( 18 ) to a water pump ( 118 ). In the housing ( 16 ) or in a nozzle body ( 12 ) communicating with it, a continuous water conduit ( 20 ) connected to the water line ( 18 ) is provided, from which a connecting conduit ( 22 ) branches off that leads to a spray conduit ( 24 ) that is approximately parallel to the water conduit ( 20 ) and has a nozzle opening ( 26 ), the water conduit ( 20 ) being closed on its free end (38).

Description:
BACKGROUND OF THE INVENTION 
   The invention is relates generally to a windshield wiper having a wiper arm, which is driven via a drive shaft and to which a wiper blade is pivotably connected. 
   Known windshield wipers have a wiper arm, which is made up of a fastening element and a hinge element, which is pivotably connected to it via a swivel joint and has a wiper rod. A hooklike end of the wiper rod engages a suspension box of a wiper blade, which is formed by two side cheeks of a middle bracket and includes a hinge bolt. The hinge thus formed guides the wiper blade over the vehicle window during the swiveling motion. The wiper blade has what is as a rule a multi-member support bracket system, with subordinate brackets pivotably connected to the middle bracket, at least some of which subordinate brackets, with claws on their ends, retain a wiper strip by its head strip. The multi-member support bracket system and spring rails placed in the head strip make it possible during wiping for the wiper strip to adapt, with a uniform contact pressure, to a curved windshield. To that end, a tension spring prestresses the swivel joint. The wiper arm is secured with its fastening element on a drive shaft and is driven by it in the wiping motion. Such windshield wipers are known, for instance from German Patent Disclosure DE 37 44 237 A1. In simple versions, subordinate brackets, also known as intermediate brackets and claw brackets, can be dispensed with. In the simplest case, the middle bracket itself has claws, with which it retains the wiper strip. 
   Windshield washing systems for vehicles are as a rule used in conjunction with windshield wipers. They are actuated if the moisture from precipitation does not suffice to clean the vehicle window. They include a water container, spray nozzles, and a pump which pumps water, sometimes admixed with cleaning and antifreeze agents, under pressure out of the water container to the spray nozzles. As a rule, the spray nozzles are secured to some part of a vehicle body, such as a hood, window frame, or the like. To prevent the spray nozzles from freezing at temperatures below the freezing point, heating elements are integrated into the spray nozzles and communicate with a power supply via plugs located on the outside. The heating elements require relatively great effort and expense for producing the spray nozzles and great effort and expense for assembly for laying the electric lines and contacting the plugs. Furthermore, the highly volatile antifreeze agents rapidly evaporate, and the nozzle openings become plugged with the residues. 
   It is already known to secure spray nozzles as additional components on the wiper blade and thus to distribute the spraying water over the wiping region directly with a short stream length. Since the spraying water is concentrated on a region in the vicinity of the wiper blade and is wiped off again in the briefest time by the wiping motion, the view is hindered only briefly by the spraying water applied. A disadvantage of such systems is that the effects of weather, especially hail and extreme sunshine, have a major effect on the flexible parts of this arrangement, which are required for spanning the jointed regions between the wiper arm and the wiper blade. The spray nozzles and water lines that are exposed to the relative wind also freeze up quickly at temperatures below the freezing point, unless enough antifreeze is added to the water. As a rule, thawing the frozen water lines and spray nozzles again can be done only with major effort. 
   In an earlier German patent application, DE 198 15 171.3, a wiper arm is described, on whose hinge element, or on a wiper rod integrally joined to the hinge element, spray nozzles are disposed. These nozzles have a nozzle body, which is accommodated in a bulge of the hinge element with an opening for the spray stream, or is clipped, protruding downward, in a lateral mount on the wiper rod. It is also possible for two nozzle bodies to be provided, which are joined together by a rigid or flexible connecting piece. The nozzle bodies can be replaced easily and are well protected against environmental factors. 
   Expediently, the spray nozzle has an outward-opening check valve, which prevents the water line from running empty if the washer system goes unused for relatively long periods, or if water escapes during wiping operation without any washing function, especially at high wiping frequencies and/or with stroke-controlled wiper arms. Furthermore, washing water and antifreeze is prevented from evaporating in the region of the spray nozzle, especially in the case of a heated spray nozzle, and narrowing or plugging up the spray nozzle with deposits. 
   A heater which is passed in the form of a wire through a water supply lead and is embodied as a heating coil in the nozzle body is integrated with the wiper system. The heater fits only one type of windshield wipers, so that a large number of different heating devices must be kept in stock. Furthermore, there are simple versions in which the nozzle bodies are integrally joined together and produced as a plastic injection-molded part. By means of the nozzle bodies distributed on the wiper arm, the spraying water is well distributed over the wiper region, especially if a spray stream is aimed at a lower region directly in front of the wiper blade. Since short stream lengths result from this arrangement, even at relatively high vehicle speed the relative wind can have only little effect on the distribution of spraying water. 
   SUMMARY OF THE INVENTION 
   According to the invention, at least one spray nozzle is disposed on a retaining element. The retaining element can be a wiper arm and/or a wiper rod. The spray nozzle has a housing, which includes a water conduit from which a connecting conduit branches off. The water conduit can also be formed by a nozzle body that is inserted into the housing. From the water conduit, a connecting conduit branches off, leading to a spray conduit that is virtually parallel to the water conduit and is closed on its free end. With only a few modifications, such an arrangement makes numerous variants possible, with which the demands for various installation situations on a wiper arm can be met. The spray nozzle is constructed from a plurality of functional units that can be put together as needed. 
   In one feature of the invention, the housing is retained, for instance clipped, in an opening of the retaining element. A nozzle body with a stub surrounding the spray conduit is inserted from outside into the opening, protruding through the retaining element, of the connecting conduit of the housing. The outer part of the nozzle body has a nozzle opening and covers the housing and the opening of the retaining element. Hence the structural parts can be quickly joined to one another separably, and they can also easily be replaced individually. The spray nozzle protrudes out of the retaining element with only the outer part of the nozzle body, and that part fits smoothly with the contour of the retaining element, so that both visually and in terms of fluidics it is not a hindrance and it causes no noise. 
   For wipers with relatively long wiper blades, a plurality of spray nozzles are needed. For this purpose, a variant of the invention provides a water conduit, for those spray nozzles located toward the front in the flow direction, which on its free end has a connection piece to a water line leading onward that leads to a further spray nozzle. Instead of the connection piece, a closure cap is clipped into the last spray nozzle, and this closure cap closes the continuous water conduit. To enable good adaptation of one of the spray nozzles and the water lines to the applicable retaining elements, instead of integrally formed straight or offset-bent connection pieces, inserted connection pieces are provided, and thus the housing and/or the nozzle body is the same for various connecting parts or closure parts. The connecting water line having the spray nozzles is optimally adapted to the existing installation space by means of a suitable selection of structural parts. 
   The visual and fluidic effect depend essentially on the extent to which the spray nozzle protrudes out of the retaining element. It is therefore expedient for the nozzle body having the orifice of the spray conduit to protrude far enough out of an opening of a retaining element that the inner wall of the spray conduit or nozzle opening, which wall is oriented toward the retaining element, is flush with the outer wall of the retaining element. As a result, despite a shallow design, the spray stream can be aimed largely parallel to the retaining element or in other words the wiper arm. An especially shallow design is obtained if the nozzle opening is formed directly into the nozzle body or into a nozzle cap and is an integral component of the nozzle body. The nozzle cap is expediently seated disconnectably on a stub of the nozzle body. In the event of wear or damage it can easily be exchanged, or it can be replaced with a nozzle cap having a different spray stream geometry. If the nozzle cap is supported on a ball seat of the stub, then the spray stream can be adjusted even after the spray nozzle has been installed. 
   As a rule, the spray conduit upstream of the nozzle opening is wider than the nozzle opening itself. It is therefore expedient to place the nozzle opening on the outer edge of the spray conduit, in order to reduce the extent of protrusion of the spray nozzle from the retaining element. This is especially simple if the nozzle opening is integrated with the nozzle body or nozzle cap. In order to carry the washing water in a streamlined way to the nozzle opening, it is advantageous that the nozzle cap has a guide body, which leads to the nozzle opening and in the installed state of the nozzle cap engages the spray conduit. 
   According to the invention, the nozzle opening is disposed in the upper region of the retaining element; this makes the impact angle of the spray stream as steep as possible. When the impact angle is steep, the impact area varies less as a function of tolerances that can occur with regard to the direction of the stream. As a rule, one nozzle opening suffices. By means of a plurality of nozzle openings disposed vertically one above the other, the wettable impact area can be increased without having the spray nozzle protrude farther out of the retaining element. 
   The nozzle body of the spray nozzle is made from plastic and is clipped into the housing, so that its continuous water conduit communicates with the water line. A connecting conduit that leads to a spray conduit with a nozzle opening branches off from the water conduit. Upon pressure buildup of the pump, water is forced out of the supply tank through the lines of the system as far as the nozzle opening, whereupon it passes through the nozzle opening into the open air. In the pressureless state, some of the water continues to flow, so that the lines are partly emptied. To prevent the lines from running empty, a variant of the invention provides a check valve. A diaphragm closes the connecting conduit in the pressureless state. The diaphragm can be located close to the nozzle opening, so that only a small volume of water is stored between the diaphragm and the nozzle opening and accordingly can escape or evaporate in an uncontrolled way. The diaphragm is embodied as a rubber-elastic tubular diaphragm, which has beads on its ends. The beads are embedded in annular grooves of the nozzle body. When the water flows in through the connecting conduit, an annular chamber at the circumference of the nozzle body is filled, and the diaphragm is spread open. In the process, the diaphragm is braced on the outside on the housing and uncovers the discharge openings of the connecting conduit and of the spray conduit at the circumference of the nozzle body. In order that only the ambient pressure and the prestressing of the diaphragm will have to be overcome for opening purposes, a ventilation bore is located on the nozzle housing. The opening pressure of the diaphragm is slight, and thus the system can be operated at a relatively small pump capacity. 
   The nozzle body can easily be made from plastic by injection molding. Its outer diameter decreases between the annular grooves on both ends, so that the tubular diaphragm on its ends is retained sealingly between the housing and the nozzle body, but in the region of the annular chamber at the circumference of the nozzle body has sufficient radial clearance that it can uncover large enough flow cross sections. The smooth outer cylindrical or conical contour is thus preserved. 
   To make the spray nozzles capable of winter operation as well, they are heated. The heating line advantageously leads through the entire water line and through the water conduits. The diaphragm valves close off the water chamber from outside and thus prevent the heated from evaporating and calcifying the spray nozzles. With the aid of the diaphragm valves, the water is also trapped in the system during periods of nonuse. Thus in pulsed spraying, the washing water can be sprayed at the right moment in front of the wiper blade. In order not to hinder the view of the driver, the water sprays during the upward motion of the wiper arms, but in downward wiping no water can dribble after it. 
   A smaller structural volume of the communicating spray nozzles is obtained by providing that the water and energy supply are integrated in one element, so that there is no need for electrical contacting of the heating and the nozzles. Good energy transmission is attained, since there is only a slight spacing between the water conduit and the nozzle opening. Making the nozzle body from plastic provides thermal insulation from the outside, so that the heat output is concentrated especially on the nozzle opening and the water. This leads to a lower energy consumption. 
   The heated water improves the cleaning action, so that not only water consumption but especially the consumption of polluting additives can be reduced. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages will become apparent from the ensuing description of the drawing. In the drawing, exemplary embodiments of the invention are shown. The drawing, description and claims include numerous characteristics in combination. One skilled in the art will expediently consider the characteristics individually as well and put them together to make useful further combinations. 
     Shown are: 
       FIG. 1 , a longitudinal section through a spray nozzle; 
       FIG. 2 , a schematic elevation of a disposition of a spray nozzle on a retaining element; 
       FIG. 3 , a section taken along the line III—III of  FIG. 2 ; 
       FIG. 4 , a variant of  FIG. 3 ; 
       FIG. 5 , a variant of  FIG. 2 , with two nozzle openings disposed in the same plane, parallel to the outer boundary of the retaining element; 
       FIG. 6 , a section taken along the line VI—VI in  FIG. 5 ; 
       FIG. 7 , a longitudinal section through a spray nozzle with an adjustable nozzle opening and with a tubular diaphragm and an inserted connection piece; 
       FIG. 8 , a longitudinal section through a spray nozzle with a nozzle cap and a tubular diaphragm as well as an end piece slipped onto it; 
       FIGS. 9–10 , a longitudinal section through variants of the nozzle cap; 
       FIG. 11 , a variant of  FIG. 1 , with a tubular diaphragm and a connection piece to a water conduit leading onward; and 
       FIG. 12 , a longitudinal section through an arrangement with a plurality of spray nozzles. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A spray nozzle  10  is secured to a pivotable part of a wiper arm, not shown in further detail. The pivotable part will hereinafter be called a retaining element  14 , and it can be a fastening part, a hinge part and/or a wiper rod connected to the hinge part, or part of a wiper blade. 
   The spray nozzle  10  comprises a housing  16 , which is separably connected by means of a connection piece  32  via a water line  18  to a water pump  118 , which from a supply tank  120  pumps washing water to the spray nozzle  10  ( FIG. 12 ). The housing  16  is made from plastic and surrounds a water conduit  20 , which is closed on its free end  38  and from which a connecting conduit  22  branches off. The connecting conduit  22  leads to a spray conduit  24  having a nozzle opening  26 . The housing  16  is clipped into an opening  34  of the retaining element  14  and is fixed and retained by means of integrally formed lugs  40  and  42 . A nozzle body  12  has a stub  30 , which surrounds the spray conduit  24  and with which, via a plug connection, it engages an opening  36  of the housing  16 . The outer part  44  of the nozzle body  12  has at least one nozzle opening  26  and covers the opening  34  in the retaining element  14 . The nozzle body  12  protrudes with the orifice  28  of the spray conduit  24  far enough out of the opening  34  of the retaining element  14  that the inner wall, toward the retaining element  14 , of the spray conduit  24  or of the nozzle opening  26  is flush with the outer wall  46  of the retaining element  14 . 
     FIG. 3  schematically shows how the spray nozzle  10  is disposed in the opening  34  of a leg  52  of the retaining element  14 . The nozzle opening  26  is located in the upper region  50  of the retaining element  14 . In a further variant, the opening  34  extends over part of the leg  52  and of the top wall  54  ( FIG. 4 ). If there are a plurality of nozzle openings  26 , they can be disposed vertically one above the other in the upper region  50  ( FIGS. 5 and 6 ). Disposing the nozzle openings  26  in the upper region  50  of the retaining element  14  results in a steep impact angle α of the stream of water, and this has a good cleaning effect. Furthermore, the impact point shifts only slightly as a function of production variations and wear. 
     FIG. 1  shows a nozzle opening  26  which is integrated with the nozzle body  12  and does not allow adjusting the spray stream. To enable adjusting the spray stream, a variant provides a ball  48 , which has a nozzle opening  26  and is press-fitted into a ball seat  56  of the spray conduit  58  ( FIG. 7 ). A further variant shows a spray conduit  60  in an integrally formed stub  62 , on which a nozzle cap  64  that has a nozzle opening  26  is seated ( FIG. 8 ).  FIG. 7  shows the nozzle cap  64  enlarged and clipped onto the stub  62 . The nozzle opening  26  is disposed in the region of the outer inner wall  68  of the spray conduit  60 . The nozzle cap  64 , on the side toward the nozzle body  86 , also has a guide body  70 , which converges on the nozzle opening  26  and engages the widened spray conduit  60 . The guide body  70  brings about a streamlined course of the water in front of the nozzle opening  26 . 
   Embodying the nozzle cap  64  in this way does not allow adjusting the nozzle opening  26 . To enable making an adjustment, a variant of the invention provides a nozzle cap  66 , which with its spherical inside surface  76  is seated on a ball seat  78  of the integrally formed stub  74  ( FIG. 10 ). 
     FIG. 1  shows a simple design of the spray nozzle  10 , which has no check valve.  FIG. 11  shows a variant of the spray nozzle  10  with a tubular diaphragm  80 , which acts as a check valve and is accommodated in an annular chamber  124 , and which on its ends having beads  92 ,  94  sealingly engages annular grooves  96 ,  98  of the nozzle body  86 . By the imposition of a pump pressure, water flows from a water line  18  through a water conduit  20  into the connecting conduit  22 , which discharges into the annular chamber  124  inside the tubular diaphragm  80  with a discharge opening  90 , and spreads the tubular diaphragm  80  open. The water enters a chamber between the tubular diaphragm  80  and the nozzle body  86  and from there flows into the spray conduit  24 , which also has a discharge opening  88  in this chamber, which discharge opening is controlled by the tubular diaphragm  80 . When the tubular diaphragm  80  lifts up from the nozzle body  86 , after a certain opening travel it presses against the housing  82 . This prevents the tubular diaphragm  80  from overstretching at relatively high spray pressures. At least one ventilation bore  84  is provided in the region of the tubular diaphragm  80  in the housing  82 , so that the air between the tubular diaphragm  80  and the housing  82  can escape from the annular chamber  124  upon opening. In the closed state, the tubular diaphragm  80  rests with intrinsic tension on the nozzle body  86 . It closes the discharge openings  88  and  90  and thus disconnects the water conduit  20  from the spray conduit  24 . The tubular diaphragm  80  comprises an elastomer. To lend the tubular diaphragm  80  sufficient clearance for motion without increasing the installation space and without deviating from a regular outer contour, the outer diameter of the nozzle body  86  is decreased in the region between the annular grooves  96  and  98 . The mean outer diameter of the nozzle body  86  also increases toward the nozzle opening  26 . As a result, both material and weight can be saved, and the available installation space can be optimally utilized. 
   Windshield wipers with relatively long wiper blades require a plurality of spray nozzles  10 . To that end, a variant of the invention provides a water conduit  20 , which on its free end  38  has a connection piece  100  to a water line  122  that leads onward. The water line  18  connects all the spray nozzles  10  to one another ( FIG. 12 ). Instead of the connection piece  100 , a closure cap  110 , which closes the continuous water conduit  20 , is clipped into the last spray nozzle  10 . To achieve the best possible adaptation of the spray nozzles  10  and the parts of the water line  18  to the respective retaining elements  14 , a plurality of variants of connection pieces  100 ,  112  and closure caps  110 ,  114  are provided.  FIG. 12  shows an offset-bent, inserted connection piece  100  and an offset-bent, inserted closure cap  110 .  FIG. 11  shows a straight, integrally formed connection piece  112 , and  FIG. 8  shows a straight closure cap  114  that is slipped on. The entire system, comprising the connecting water line  112  and the spray nozzles  10 , can thus be adapted optimally by means of a suitable selection of component parts. 
   A heating line  116  leads through the water lines  18 ,  122  and the water conduits  20  of the spray nozzles  10 . The nozzle body  86 , which is expediently embodied in one piece, is produced as a plastic injection-molded part. As a result, the water in the nozzle body  86  is thermally insulated, so that even at low temperatures only a slight heating output is necessary. This kind of internal heating and a favorable selection of the materials used for the component parts employed result in a small structural volume and economies in terms of energy and expense.