Abstract:
A washer nozzle for a screen wash system of a motor vehicle has a pre-assembled structural unit of a jet insert and a check valve. This structural unit is pressed into a shaft of a housing. This makes the washer nozzle particularly easy to install.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to German Patent Application No. 10 2015 207 940.6, filed Apr. 29, 2015, the contents of such application being incorporated by reference herein. 
       FIELD OF THE INVENTION 
       [0002]    The invention concerns a washer nozzle for a screen wash system of a motor vehicle, with a housing, with a jet insert inserted in the housing and sealed against this, with a connection for a washing fluid line for supplying screen washing fluid, with a water outlet of the jet insert for spraying washing fluid, and with a check valve blocking the back flow of the washing fluid from the water outlet to the connection. 
       BACKGROUND OF THE INVENTION 
       [0003]    Such washer nozzles are often used in screen wash systems of modern motor vehicles and are known in practice for cleaning windscreens, rear windows or headlamp lenses. The washer nozzle generates a jet of washing fluid depending on the shape of the jet insert. The check valve prevents the washing fluid from running back when the screen wash system is at rest. Such a back flow would lead to greatly delayed response of the screen wash system on restart. 
         [0004]    A washer nozzle is known in practice in which a check valve is arranged directly behind the connection of the housing. For this, the check valve has a catch connection and a seal in the connection. The disadvantage with this washer nozzle is that it is very complex to construct and install. 
       SUMMARY OF THE INVENTION 
       [0005]    An aspect of the invention is based on refining a washer nozzle of the type cited initially so that it is particularly easy to install. 
         [0006]    This problem is achieved according to an aspect of the invention in that the jet insert with the check valve is configured as a pre-assembled structural unit. 
         [0007]    With this design, the structural unit of the check valve and housing can easily be joined together for final installation of the washer nozzle. This substantially facilitates installation of the washer nozzle. The check valve with the jet insert also forms a structural unit which is simple to install. 
         [0008]    According to a further advantageous refinement of the invention, the check valve has particularly few components and can be installed particularly easily if the jet insert has a valve connector, the valve connector has a channel, the channel is guided from an opening facing the housing to an opening facing the water outlet, and one of the openings is closed by an elastic membrane. 
         [0009]    According to a further advantageous refinement of the invention, installation of the washer nozzle is simplified further if the membrane is fixedly clamped on the valve connector. With this configuration, in the simplest case the check valve with the one membrane requires only a single component for the check valve. 
         [0010]    According to a further advantageous refinement of the invention, the check valve is structured particularly simply if the opening of the channel facing the washer outlet is arranged on a casing surface of the valve connector, and the membrane surrounds the valve connector in the region of the opening facing the water outlet. 
         [0011]    According to a further advantageous refinement of the invention, installation of the washer nozzle is simplified further if the jet insert comprises the valve connector with the channel. 
         [0012]    According to a further advantageous refinement of the invention, the check valve is structured particularly simply if the valve connector has a round cross section and the membrane is formed as a hose and is pushed over the valve connector. 
         [0013]    According to a further advantageous refinement of the invention, the washer nozzle can be produced particularly economically if the membrane is made of a rubber elastic material. 
         [0014]    According to another advantageous refinement of the invention, the pretension force of the check valve can be set particularly easily if the hose-like membrane has a slot next to the opening facing the water outlet. 
         [0015]    According to a further advantageous refinement of the invention, the seal of the housing and the guidance of the washing fluid through the channel are structured particularly simply if the housing has a sealing seat against the free end of the valve connector. 
         [0016]    According to a further advantageous refinement of the invention, installation of the washer nozzle is simplified further if the jet insert has a press fit in a shaft of the housing. 
         [0017]    The washer nozzle allows the distribution of the washing fluid jet over a wide spray area if the washer nozzle is configured to generate an oscillating jet of washing fluid. This configuration means that only a small number of jet inserts is required to clean a large surface area, which simplifies installation of the washer nozzle. Washer nozzles for generating an oscillating jet of washing fluid are often known as fluidic nozzles and are known in practice. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Aspects of the invention allow for numerous embodiments. To clarify the basic principle further, one of these is shown in the drawing and described below. The drawings show: 
           [0019]      FIG. 1  a longitudinal section through a washer nozzle provided for installation in a motor vehicle, 
           [0020]      FIG. 2  a jet insert of the washer nozzle from  FIG. 1  with a check valve before installation, 
           [0021]      FIG. 3  a housing and a structural unit of the washer nozzle before installation. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]      FIG. 1  shows a washer nozzle  1  provided for installation in a motor vehicle, with a housing  2  and a jet insert  3  and a check valve  4 . The housing  2  has a connection  5  for connection of a washing fluid line (not shown). A water outlet  6  for spraying washing fluid is arranged on the jet insert  3 . The housing  2  has a shaft  7  for receiving the jet insert  3 , and a washing fluid channel  8  guided up to the check valve  4 . The check valve  4  has a valve connector  9 , at the free end of which a sealing seat  10  against the washing fluid channel  5  of the housing  2  is arranged. The jet insert  3 , close to the water outlet  6 , also has a sealing seat  11  against the housing  2 . Various elements  12  are arranged in the jet insert  3  to generate an oscillating jet of washing fluid. 
         [0023]    The housing  2  may furthermore have catch hooks (not shown) for fixing in the motor vehicle, or receivers for a heating device (also not shown). Evidently, the housing  2  may also comprise several shafts  7  for receiving several jet inserts  3 . 
         [0024]      FIG. 2  shows a jet insert  3  with individual components of the check valve  4  shown in  FIG. 1  before installation. It is evident here that the jet insert  3  is produced integrally with the valve connector  9 . The valve connector  9  has a channel  15  guided from an opening  13  facing the housing  2  to an opening  14  facing the water outlet  6 . The opening  14  facing the water outlet  6  is arranged on the casing surface of the valve connector  9 . The check valve  4  has a hose-like rubber elastic membrane  16  which is pushed over the valve connector  9  for installation, and in the mounted state shown in  FIG. 1  covers the opening  14  facing the water outlet  6 . After being pushed on, the membrane  16  is fixedly clamped to the valve connector  9 . 
         [0025]      FIG. 3  shows a pre-assembled structural unit of a jet insert  3  and check valve  4  before installation in the housing. In the exemplary embodiment shown, the membrane  16  has a slot  17 . In another exemplary embodiment (not shown), the membrane  16  may also be configured without a slot, as a thin-walled hose piece corresponding to the proposed pretension force. For installation, this structural unit of jet insert  3  and check valve  4  is simply introduced into the shaft  7  of the housing  2  and held by means of a press fit on the sealing seats  10 ,  11  described in  FIG. 1 . 
         [0026]    When washing fluid is introduced into the housing  2  via the connection  5  shown in  FIG. 1 , it reaches—via the washing fluid channel  8 —the opening  13  of the check valve  4  facing the housing  2 . Via the channel  15  in the valve connector  9 , the washing fluid then reaches the opening  14  in the valve connector  9  facing the water outlet  6 . The membrane  16 , covering the opening  14  in the valve connector  9  facing the water outlet  6 , is pressed radially outwards under the pressure of the washing fluid so that the washing fluid reaches the elements  12  in the jet insert  3 . These elements  12  at the water outlet  6  generate an oscillating jet of washing fluid. When no washing fluid is conveyed, the membrane  16  lies on the valve connector  9  and closes the opening  14  facing the water outlet  6 . Thus no air can enter the washing fluid channel  8 .