Abstract:
The invention relates to a device for dispensing a liquid, including a piston that is movable within a chamber and a nozzle connected to the piston such that the movement of the piston causes the movement of the nozzle, wherein one end of the piston engages the chamber so as to form a non-return valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention is the US national stage under 35 U.S.C. §371 of International Application No. PCT/FR2011/052130, which was filed on Sep. 15, 2011 and which claims the priority of application FR 1057506 filed on Sep. 20, 2010 the content of which (text, drawings and claims) is incorporated here by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a device for dispensing a liquid, including a nozzle whose movement is caused by a piston, and integrating a non-return valve function. 
     BACKGROUND 
     In the prior art, we know the document FR2666777 which describes a telescopic nozzle system for a motor vehicle. This nozzle consists of an actuator containing a window washing liquid under pressure which exerts a thrust on a piston that is connected to the tip of the nozzle and rises so as to position it opposite the windshield. The window washing liquid circulates in a passage that goes through the piston and pushes a ball which closes an opening, and then penetrates into the head of the nozzle so as to be projected against the windshield. In this device, a conventional non-return valve is placed in the conduit of the rod of the piston in order to ensure the lifting of the tip of the nozzle and to establish a connection between the washing liquid supply pipes, in order to ensure the spraying of the washing liquid against the surface to be cleaned. 
     SUMMARY 
     In the supply pipes of the prior art, a conventional non-return valve is simply placed between two pipe sections, in such a manner as to avoid the return of the fluid to the washing reservoir and avoid an excessively long pulse for a subsequent washing cycle. 
     With a view to decreasing the number of parts and simplifying the installation of the supply pipes, the invention proposes not simply to eliminate the non-return valve, but to have this non-return function be carried out by an already existing part, namely in this instance the piston itself, by way of its cooperation with the chamber in which it slides. 
     In order to preserve the non-return valve function and overcome the drawbacks of draining the supply circuit, the invention has developed a device for dispensing a liquid, advantageously a washing liquid, the piston playing the role of a non-return valve in such a manner as to make it possible to maintain the liquid level as close as possible to the nozzle, and thus, as soon as the wash command pulse has occurred, the washing liquid gushes out of the nozzle. 
     For this purpose, the present invention relates to a device for dispensing a liquid, including a piston that is movable in a chamber and a nozzle connected to the piston such that the movement of the piston causes the movement of the nozzle, one end of the piston engaging with the chamber so as to form a non-return valve. 
     According to another feature, the lower end of the piston has a convex, advantageously spherical shape. 
     According to another advantageous feature, the nozzle is stationary relative to the piston. 
     Advantageously, the piston is a single piece. 
     According to a variant, the body of the piston through which the washing liquid penetrates has a truncated shape and the seal of the spherical portion of the piston on the truncated portion of the body is produced on a circular line. 
     According to another variant, the chamber consists of a tubular part closed by two stoppers. 
     Advantageously, the piston is provided with a sealing washer, above the portion in the form of a spherical cap. 
     Advantageously, the piston does not have a sealing washer at the end of the piston. 
     According to a feature, the supply pipe secured to the lower end of the body is bent, and the piston does not descend to the bend. 
    
    
     
       DRAWINGS 
       Other features and advantages of the invention will become clear following a reading of the description given below for information, in reference to the appended drawings. 
         FIG. 1  is a plan view diagrammatically showing a device comprising a non-return valve in the closed position according to the invention. 
         FIG. 2  is a plan view diagrammatically showing a device comprising a non-return valve in the open position according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a plan view diagrammatically showing a device  1  comprising a non-return valve  2  in the closed position according to the invention. The device  1  is a telescope including a piston  3  and a body  4 . The body  4  is a tubular part  4   d  closed by two stoppers  4   a ,  4   b  at each one of its ends. The piston  3  comprises at its upper end a nozzle  5  and at its lower a convex, preferably spherical, cap  6 . The piston  3  is directed downward under the action of a compression spring  7  bearing against the bottom of the upper closing stopper  4   a  of the body  4  and against a shoulder  3   a  of the rod  3   b  of the piston  3 . The lower end of the piston  3  comprises, above the spherical cap  6 , two transverse openings  3   c  opening into an axial pipe  3   d  of the piston  3 , making it possible to supply a washing liquid to the nozzle  5  placed at the upper end of the piston  3 . Above the openings  3   c , the piston  3  is provided with a washer  8  placed in a circular groove  3   e . This washer  3   e  prevents the washing liquid from being introduced into the circular space  9  where the compression spring  7  is located. The lower closing stopper  4   b  of the body  4  includes axially a through opening  4   c  to which a pipe  10  is screwed, which is provided with a shoulder bearing against the stopper  4   b . The pipe  10  is bent at a right angle. The washing liquid  16  penetrates into the pipe  10  along the arrow  17 . The circular opening of the body  4  opens into the interior of the body  4  with a flared portion  4   c  having a substantially truncated shape forming a container of the end of the spherical cap  6  of the piston  3 . The seal is achieved in this case on a circular line  20 . 
     When the end of the piston  3  bears against the flared portion  4   c , the seal is achieved and it forms the non-return valve  2 . The flared portion  4   c  can be of cylindro-spherical shape. In this manner, the seal is achieved over a surface. During operation, the piston  3  can move only along its axis. In this case, a dog point screw  11  is screwed in the upper stopper  4   a , the dog point  12  running into a groove  13  produced on the periphery of the piston  3  along its longitudinal axis. In reference to the figure, the groove  13  is helical, consequently, during operation, the nozzle  5  moves along a helical trajectory during the projection of the liquid. 
       FIG. 2  is a plan view diagrammatically showing a device  1  comprising the non-return valve  2  in the open position according to the invention, that is in an operating position that is substantially halfway in the helical groove  13 , taking into consideration the position of the teat  12  of the screw  11 , which is located between the beginning  13   a  of the groove  13 , visible on the rod extracted from the piston  3 , and the end  13   b  of the groove  13  visible on the internal rod of the piston  3 . 
     In the figure, the liquid penetrates into the body  4  through the flared opening  4   c  which, under the pressure of the liquid  16  in the direction of the arrow  18 , pushes the piston  3  upward against the force exerted by the compression spring  7 . Simultaneously, the liquid penetrates through the two openings  3   c  into the axial conduit  3   d  of the piston  3  to the nozzle  5 , where it is projected along the arrow  19  against the surface to be cleaned. Preferably, the movement of the piston causes the movement of the nozzle  5  mechanically, and thus directly. 
     After the end of the cycle, the pressure of the liquid decreases and the spring  7  pushes back the piston  3  until it closes the flared opening  4   c  and implements the non-return valve function. 
     Naturally, the invention is obviously not limited to the embodiment example described more specifically and represented in reference to the appended drawings; on the contrary, it encompasses all the variants.