Abstract:
This valve ( 100 ) comprises: a body ( 101 ); a first channel (III) for channelling the flow of a fluid; a second channel ( 112 ) for channelling the flow of a fluid; a first valving element ( 130 ) which is movable translationally in a first direction (X 112 ), between an open position and closed position of the or each first channel ( 111 ), the body ( 101 ) fouling a first seat ( 123 ) for the first valving element ( 130 ); and a second valving element ( 130 ) which is movable translationally in a second direction (X 112 ), between an open position and a closed position of the or each second channel ( 112 ); the first direction (X 112 ) and the second direction (X 112 ) being parallel or coinciding with each other. The first valving element ( 130 ) defines a housing ( 140 ) for the second valving element ( 130 ). The first valving element ( 130 ) forms a second seat ( 136 ) for the second valving element ( 130 ).

Description:
RELATED APPLICATIONS 
       [0001]    The present application is a §371 U.S. national stage entry of International Application No. PCT/FR2009/052454, filed Dec. 8, 2009, which claims the priority of France patent application No. 08 58413 filed Dec. 9, 2008, all of which are incorporated herein by reference in its entirety. 
     
    
     FIELD 
       [0002]    The present invention relates to a valve for spraying coating material, and to an atomizer including such a valve. 
       BACKGROUND 
       [0003]    EP-A-0 274 322 describes a spraying installation for spraying a coating material onto articles to be coated, in which installation a multi-axis robot moves an atomizer for spraying coating material facing articles to be coated. In the example described below, the coating material is a primer, a paint, or a varnish, and the articles to be coated are motor vehicle bodies transported by a conveyor. 
         [0004]    The atomizer is equipped with a reservoir containing the volume of paint that is necessary for performing the stage of spraying paint onto the vehicle body. After that stage, it is necessary to fill the reservoir again by coupling the atomizer to a preselected paint circuit, sometimes referred to as a “circulating” paint circuit. When filling the reservoir again, it is often necessary to change coating material, in particular so as to change the shade of color of the paint. It is therefore necessary to clean the reservoir and the channels of the atomizer, and the coupling zones, by rinsing them with a cleaning material such as a solvent. 
         [0005]    That is why a prior art paint spraying installation generally includes at least two distinct coupling means placed respectively between the atomizer and the paint circuit and between the atomizer and the solvent circuit. Those coupling means comprise, amongst others, two distinct valves mounted on and/or in the atomizer for the purpose of controlling, respectively and successively, the flow of solvent and the flow of paint. During the cleaning stage, residual waste solvent and paint must also be collected and then conveyed to a treatment unit, which requires an additional valve. This also requires corresponding additional control members and components for actuating the various valves. 
         [0006]    Unfortunately, said juxtaposed valves in the atomizer represent considerable overall size, regardless of their respective dimensions. That overall size increases the overall size of the atomizer and makes its structure more complex. In addition, that overall size reduces access to the other components of the atomizer during maintenance operations. 
         [0007]    In addition, those three valves are interconnected via a network of common channels, in particular so as to make it possible to rinse the valve and the ducts for enabling paint to flow towards the reservoir. Unfortunately, the volume of those common channels is filled firstly with paint for the reservoir-filling and spraying stages and secondly with solvent for the cleaning stages, so that that volume gives rise to wastage of paint and to a relatively high consumption of solvent. Paint is also wasted when the reservoir is filled again without changing the shade of paint. 
         [0008]    A particular object of the present invention is to remedy those drawbacks by proposing a valve that is compact, that significantly reduces the amount of paint wasted and the solvent consumption, and that simplifies the structure of the atomizer. 
       SUMMARY 
       [0009]    To this end, the invention provides a valve comprising:
       a body;   at least one first duct for channeling the flow of a fluid;   at least one second duct for channeling the flow of a fluid;   a first needle mounted to move in translation, in a first direction, between an open position and a closed position for opening and closing the or each first duct, the body forming a first seat for the first needle; and   a second needle mounted to move in translation, in a second direction, between an open position and a closed position for opening and closing the or each second duct.       
 
         [0015]    This valve is characterized in that the first direction and the second direction are parallel or coincide, while the first needle defines a recess for receiving the second needle, and while the first needle forms a second seat for the second needle. 
         [0016]    According to other advantageous but optional characteristics of the invention, taken in isolation or in any technically feasible combination:
       the first needle and the second needle are circularly symmetrical respectively about the first direction and about the second direction, and the first needle and the second needle are arranged coaxially;   the body defines the first duct, and the second needle has an internal cavity forming a portion of the second duct;   the body has an opening common to the first duct and to the second duct;   the first needle and the second needle come flush with said opening;   the valve further comprises at least one resilient member for urging the first needle and the second needle back into their respective closed positions in which they close the first duct and the second duct, and the first needle and the second needle have respective thrust surfaces arranged in such a manner as to transmit thrust forces exerted by a thrust fluid, such as compressed air, in the first direction or in the second direction in opposition to the resilient member;   at least one resilient member is formed by a crest-to-crest multi-turn spring;   the first duct extends substantially transversely to the second duct;   the first duct and the second duct are arranged to receive a first type of fluid, such as a cleaning material, or a second type of fluid, such as a coating material;   the first seat and the second seat are frustoconical in shape; and   the first needle and the second needle present wetted surfaces that are substantially locally tangential to the lines of flow of the fluids, in such a manner as to limit fluid retention.       
 
         [0027]    In addition, the invention provides an atomizer for spraying coating material, said atomizer including a valve as described above. 
         [0028]    The invention can be well understood and its advantages also appear from the following description, given merely by way of non-limiting example and with reference to the accompanying drawings, in which: 
     
    
     
       FIGURES 
         [0029]      FIG. 1  is a section view of a first embodiment of a valve of the invention; 
           [0030]      FIG. 2  is a section view of a second embodiment of a valve of the invention; 
           [0031]      FIG. 3  is a section view similar to  FIG. 1 , showing a third embodiment of the invention; 
           [0032]      FIGS. 4 and 5  are section views on a smaller scale, showing the  FIG. 2  valve placed in opening configurations; 
           [0033]      FIGS. 6 and 7  are section views, on a smaller scale, showing the  FIG. 3  valve placed in opening configurations; and 
           [0034]      FIG. 8  is a fragmentary section view of an atomizer of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]      FIG. 1  shows a valve  100  comprising a body  101 , a first duct  111  and a distinct second duct  112 , in which duct fluids can flow that are used during filing, spraying, and cleaning stages, e.g. paint, solvent, and compressed air. 
         [0036]    The valve  100  further comprises a first needle  130  and a second needle  160 , which needles have the function of allowing or preventing fluid flow. The body  101  houses the first needle  130  and the second needle  160 . In addition, the first needle  130  defines a recess  140  adapted to receive a substantial portion of the second needle  160 . 
         [0037]    The body  101  is made up of an upstream half-body  102  and of a downstream half-body  103 . The upstream half-body  102  is formed essentially of an upstream end plate  104  and of an upstream cylindrical wall  105  that are united with each other. The downstream half-body  103  is formed essentially of a downstream end plate  106  and of a downstream cylindrical wall  107 . The upstream and downstream end plates  104  and  106  are generally disk-shaped. The upstream and downstream end plates  104  and  106  are provided respectively with an upstream through opening  104 . 1  and with a downstream through opening  106 . 1 . The upstream opening  104 . 1  and the downstream opening  106 . 1  are of circular shape and make it possible for the fluids to pass through the first duct  111  and the second duct  112 , as described in detail below. 
         [0038]    The upstream half-body  102  and the downstream half-body  103  are assembled together by the upstream cylindrical wall  105  and the downstream cylindrical wall  107  being fastened together. The upstream and downstream cylindrical walls  105  and  107  may be fastened together by clip-fastening or by screw-fastening, as in the first and second embodiments shown in  FIGS. 1 and 2 , or by any other equivalent fastening means. 
         [0039]    In the present patent application, the terms “upstream” and “downstream” are used with reference to the general direction of flow of the fluids through the first duct  111  and through the second duct  112 . These flows are shown in  FIGS. 4 to 7  by lines of flow L 211 , L 212 , L 311 , and L 312 . 
         [0040]    The first needle  130  is mounted to move in translation in a first direction represented by an axis X 112  that is vertical in  FIG. 1 . The second needle  160  is mounted to move in translation in a second direction that is also represented by the axis X 112 . In other words the first direction and the second direction in which the first needle  130  and the second needle  160  respectively move are co-linear and coincide as a common axis X 112 . 
         [0041]    The first needle  130  is mounted to move between an open position in which it opens the first duct  111 , and a closed position in which it closes said first duct. The second valve  160  is mounted to move between an open position in which it opens the second duct  112 , and a closed position in which it closes said second duct.  FIG. 1  shows the valve  100  as placed in its closure configuration, with the first needle  130  and the second needle  160  being in their respective closed positions. In other words, in  FIG. 1 , the first needle  130  and the second needle  160  are in their closed positions in which they close the first duct  111  and the second duct  112  respectively. In the configuration shown in  FIG. 1 , no fluid can flow in the first duct  111  or in the second duct  112 . 
         [0042]    The first needle  130  is made up of a first upstream end-piece  132  that is frustoconical in shape, of a first upstream cylinder  133 , of a first ring  134 , and of a first downstream cylinder  135 . The axis X 112  is common to the first upstream end-piece  132 , to the first upstream cylinder  133 , to the first ring  134 , and to the first downstream cylinder  135 . The first needle  130  is thus circularly symmetrical about the first translation direction constituted by the axis X 112 . The first needle  130  is hollow. More precisely, the first upstream end-piece  132 , the first upstream cylinder  133 , the first ring  134 , and the first downstream cylinder  135  have hollow central regions that communicate with one another. 
         [0043]    The second needle  160  is made up of a second upstream end-piece  162  that is frustoconical in shape, of a second upstream cylinder  163 , of a second ring  164 , and of a second downstream cylinder  165 . The axis X 112  is common to the second upstream end-piece  162 , to the second upstream cylinder  163 , to the second ring  164 , and to the second downstream cylinder  165 . The second needle  160  is thus circularly symmetrical about the second translation direction constituted by the axis X 112 . The second needle  160  is hollow. More precisely, the second upstream end-piece  162 , the second upstream cylinder  163 , the second ring  164 , and the second downstream cylinder  165  have hollow central regions that communicate with one another. 
         [0044]    The first needle  130  and the second needle  160  are thus arranged coaxially about the axis X 112 . 
         [0045]    In the present patent application, the terms “interconnect”, “connect”, “couple”, and “communicate” refer to fluid communication, i.e. to a link enabling a gaseous or liquid fluid to flow or to circulate between two or more points or parts. Such a link may be direct or indirect, i.e. formed by a duct, by a pipe, or by a channel etc. Similarly, the nouns derived from these verbs, such as “interconnection”, “connection”, and “coupling”, concern such fluid communication. 
         [0046]    Close to the upstream opening  104 . 1 , the body  101  forms a first seat  123  for the first needle  130 . More precisely, the first seat  123  is constituted by a frustoconical surface of axis X 112  that is provided in the upstream half-body  102  and that converges towards the axis X 112  going towards the upstream opening  104 . 1 . The first upstream end-piece  132  has an outside radial surface  131  having a frustoconical shape that is complementary to the frustoconical shape of the seat  123 . When the first needle  130  is in the closed position, the outside radial surface  131  bears in leaktight manner against the seat  123 . The first needle  130  thus closes the first duct  111 . 
         [0047]    In the present application the adjectives “radial” and “axial” are used with reference to the general orientation of the element they describe. For example, a surface is said to be “radial” or “axial” depending on whether a normal to said surface is oriented perpendicularly or parallel to the axis X 112 . 
         [0048]    In the present application, the adjectives “inside” and “outside” respectively designate an element facing towards the axis X 112  and an element facing away from the axis X 112 . 
         [0049]    The first needle  130  forms a second seat  136  for the second needle  160 . The seat  136  is formed by an inside radial surface of the second upstream end-piece  132 , which surface is of frustoconical shape. The second needle  160  has a terminal plate  166  situated at the upstream end of the second upstream end-piece  162 . 
         [0050]    The terminal plate  166  has terminal axial surface that is disk-shaped, and that closes off a substantial fraction of the upstream opening  104 . 1 . The terminal plate  166  also has an outside radial surface  161  having a frustoconical shape that is complementary to the frustoconical shape of the second seat  136 . When the second needle  160  is in the closed position, the outside radial surface  161  of the second upstream end-piece  162  bears in leaktight manner against the second seat  136 . The second needle  160  thus closes the second duct  112 . 
         [0051]    The first needle  130  and the second needle  160  come flush with the upstream opening  104 . 1 . More precisely, the respective terminal axial surfaces of the first upstream end-piece  132  and of the second upstream end-piece  162  come flush with an outer surface  104 . 2  of the upstream end plate  104 . This arrangement makes it possible to minimize the overall size of the valve  100  and to reduce coating material consumption and cleaning material consumption. 
         [0052]    The body  101  defines the first duct  111  that is machined in the upstream half-body  102 . The first duct  111  extends rectilinearly along an axis X 111 . A substantial portion of the second duct  112  is formed by an internal cavity  170  formed by a blind and cylindrical recess of axis X 112  that is provided through the second needle  160 . The second duct  112  thus extends essentially along the axis X 112  The axis X 111  of the first duct  111  is substantially transverse to the axis X 112 . The adverb “substantially” indicates that the axis X 111  and the axis X 112  may be disjoint, i.e. non-intersecting. In the plane of  FIG. 1 , the axis X 111  and the axis X 112  form an angle A of about 70°. 
         [0053]    The first needle  130  can slide inside the body  101  and following a sliding and pivoting connection along and about the axis X 112 . In practice, the outside radial surface of the first upstream cylinder  133  has a diameter D 133.1  that is slightly smaller than the diameter D 102  of the inside radial and cylindrical surface of the upstream half-body  102 . The difference between the diameter D 133.1  and the diameter D 102  corresponds to operating clearance allowing the first upstream cylinder  133  to slide inside the upstream half-body  102 . 
         [0054]    Similarly, the diameter D 135  of the outside radial surface of the first downstream cylinder  135  is slightly smaller than the diameter D 105  of the inside radial surface of the upstream cylindrical wall  105 . The difference between the diameter D 105  and the diameter D 135  corresponds to operating clearance that allows the first downstream cylinder  135  to slide in the upstream cylindrical wall  105 . 
         [0055]    In analogous manner, the second needle  160  can slide inside the first needle  130  and in the downstream half-body  103 , sliding and pivoting along and about the axis X 112 . For this purpose, the diameter D 163  of the outside radial surface of the first upstream cylinder  163  is slightly smaller than the diameter D 133.2  of the inside radial surface of the first upstream cylinder  133 . The difference between the diameter D 133.2  and the diameter D 163  corresponds to operating clearance that allows the first upstream cylinder  163  of the second needle  160  to slide in the first upstream cylinder  133  of the first needle  130 . 
         [0056]    Similarly, the diameter D 164  of the outside radial surface of the first ring  164  is slightly smaller than the diameter D 140  of the inside radial surface of the recess  140  that is defined by the inside radial surface of the first downstream cylinder  135 . The difference between the diameter D 164  and the diameter D 140  corresponds to operating clearance that allows the first ring  164  to slide in the recess  140 . In addition, the diameter D 165  of the outside radial surface of the first downstream cylinder  165  is slightly smaller than the diameter D 108  of the inside radial surface of an inner wall  108  of cylindrical shape that belongs to the downstream half-body  103 . The difference between the diameter D 108  and the diameter D 165  corresponds to operating clearance that allows the first downstream cylinder  165  to slide in the inner wall  108 . 
         [0057]      FIG. 8  shows an atomizer  1  having a body  11  housing a reservoir  10  containing the coating material, and a high-voltage unit  12 . The atomizer  1  has a valve  100  described above with reference to  FIG. 1 . A connection duct  13  connects the upstream of the reservoir  10  to the upstream opening  104 . 1  of the valve  100 . The connection duct  13  is partially formed by the second duct  112 . The downstream of the reservoir  10  is connected to an atomizer member (not shown) via a feed duct  14 . The body  11  has an outside surface  15  surrounding the upstream opening  104 . 1   
         [0058]    As shown in  FIG. 1 , the upstream opening  104 . 1  is common to the first duct  111  and to the second duct  112 . When the valve  100  is in the opening configuration, the paint and the solvent can flow successively through the upstream opening  104 . 1  during the stages of cleaning and of filling the reservoir  10  of the atomizer  1 . The second upstream end-piece  162  of the second needle  160  has orifices  172  distributed about the axis X 112 . Via the orifices  172 , the fluids (paint, solvent, and compressed air) can flow from the upstream opening  104 . 1  towards the internal cavity  170 , and thus towards the second duct  112 . 
         [0059]    The diameter D 111  of the first duct  111  is about 3 millimeters (mm), because it serves to pass solvent and compressed air for the purpose of cleaning the channels and the atomizer member of the atomizer  1 . The diameter D 112  of the second duct  112 , as measured in its narrowest portion, is about 8 mm, because it serves to pass paint. Thus, the first duct  111  and the second duct  112  are arranged to receive respectively a first type of fluid such as a cleaning material, constituted by solvent and by compressed air, or a second type of fluid such as a coating material constituted by paint. 
         [0060]    The valve  100  has a length L 100 , as measured parallel to the axis X 112 , of about 49 mm. The valve  100  has a width W 100 , as measured perpendicularly to the axis X 112 , of about 44 mm. Thus, the valve  100  is particularly compact. 
         [0061]    This compactness of the valve  100  facilitates access to the other components of the atomizer  1  during maintenance operations, and it limits wastage of paint and consumption of solvent. In addition, this compactness limits head losses generated by the valve  100  on the flows of paint and of solvent, thereby improving the effectiveness of the cleaning and increasing the flow-rate of filling of the reservoir  10 , and thus reducing the time required for changing shades of paint. 
         [0062]    The first needle  130  and the second needle  160  have respective thrust surfaces  137  and  167  that are arranged in such manner as to transmit respective thrust forces F 137  and F 167  exerted by a thrust fluid, which is compressed air in this example. The compressed air is injected onto the first thrust surface  137  via a first thrust chamber  138  and via a first thrust channel  139 . The compressed air is brought onto the second thrust surface  167  via a second thrust chamber  168  and via a second thrust channel  169 , which channel is provided through the upstream cylindrical wall  105  and communicates with the second thrust chamber  168  through the first downstream cylinder  135 . The thrust surfaces  137  and  167  are fainted by respective upstream axial surfaces of the rings  134  and  164 . 
         [0063]    The thrust forces F 137  and F 167  are distributed respectively over the set of thrust surfaces  137  and  167 . The resultants of the thrust forces F 137  and F 167  are exerted parallel to the axis X 112 , i.e. in the first translation direction in which the first needle  130  moves in translation, and in the second translation direction in which the second needle  160  moves in translation. 
         [0064]    In order to urge the first needle  130  and the second needle  160  back into their respective closed positions in which they close the first duct  111  and the second duct  112 , the valve  100  further includes a first spring  191  and a second spring  192 . The first spring  191  and the second spring  192  respectively constitute a first resilient member and second resilient member for urging the first needle  130  and the second needle  160  back into their respective closed positions in which they close the first duct  111  and the second duct  112 . The first spring  191  and the second spring  192  work in compression in opposition to respective ones of the thrust forces F 137  and F 167 . 
         [0065]    The surface areas of the thrust surfaces  137  and  167  are determined as a function of the available thrust fluid pressure and of the return forces exerted by the first spring  191  and by the second spring  192 . The first spring  191  and the second spring  192  are dimensioned as a function of the paint and solvent feed pressures that are exerted on their upstream end-pieces of type  132 . These feed pressures are defined for the paint installation in which the valve  100  is used. 
         [0066]    The first spring  191  is a conventional helical wire spring. Alternatively, it may be a crest-to-crest multi-turn spring. For the same length unloaded, a crest-to-crest multi-turn spring offers stiffness greater than the stiffness offered by a conventional helical wire spring. The first spring  191  is flanked laterally by the downstream cylindrical wall  107  and by an inner wall  108  belonging to the downstream half-body  103 . The first spring  191  is in abutment firstly against the downstream end plate  106  and secondly against an upstream axial surface of the first downstream cylinder  135 . 
         [0067]    The second spring  192  is a conventional helical wire spring. The second spring  192  is flanked laterally by the downstream cylindrical wall  107  and by the inner wall  108 . The second spring  192  is mounted to bear firstly against the downstream end plate  106  and secondly against an upstream axial surface of the first ring  164 . 
         [0068]    The valve  100  also includes a plurality of sealing zones that are arranged between its various components for the purpose of making them leaktight relative to the fluids flowing through the valve  100 , which fluids are constituted by paint, solvent, and compressed air. The first needle  130  and the second needle  160  are sealed by O-ring seals bearing against radial surfaces, thereby increasing the axial compactness of the valve  100 . These radial surfaces correspond to the cylindrical portions of the first needle  130  and of the second needle  160 . Implementing the sealing on radial surfaces rather than on axial surfaces makes it possible to retain fluids while eliminating “dead” zones. 
         [0069]      FIG. 2  shows a second embodiment of a valve  200  of the invention. The description of the valve  100  that is given above can be transposed to the valve  200 , except for the significant differences mentioned below. An element of the valve  200  that is identical or that corresponds to an element of the valve  100  bears the same numerical reference plus 100. 
         [0070]    This transposition thus defines the valve  200 , a body  201 , an upstream half-body  202 , a downstream half-body  203 , an upstream end plate  204 , an upstream opening  204 . 1 , an upstream cylindrical wall  205 , a downstream end plate  206 , a downstream opening  206 . 1 , a downstream cylindrical wall  207 , a first duct  211  of axis X 211 , and of diameter D 211 , a second duct  212  of axis X 212  and of diameter D 212 , a first seat  223 , a first needle  230  with a first upstream end-piece  232 , a first upstream cylinder  233 , a first ring  234 , a first downstream cylinder  235 , a second seat  236 , a first thrust surface  237 , a first thrust chamber  238 , a recess  240 , a second needle  260  with a second upstream end-piece  262 , a second upstream cylinder  263 , a second ring  264 , a second downstream cylinder  265 , a terminal plate  266 , a second thrust surface  267 , a second thrust chamber  268 , an internal cavity  270 , a first spring  291 , and a second spring  292 . 
         [0071]    The valve  200  differs from the valve  100  essentially by the functions of its first and second ducts, i.e. by the geometrical shapes and dimensions of the first duct  211  and of the second duct  212 . The first duct  211  and the second duct  212  extend respectively along an axis X 211  and along an axis X 212  that are perpendicular, i.e. that form an angle of 90° between them in the plane of  FIG. 2 . The valve  200  is more compact than the valve  100 , because the length of the valve  200  is 43 mm and its width is 36 mm. 
         [0072]    The diameter D 211  of the first duct  211  is about 8 mm, because it serves more particularly to pass paint. The diameter D 212  of the second duct  212 , as measured in its narrowest portion, is about 3 mm because it serves to pass solvent and compressed air for cleaning the channels and the atomizer member of the atomizer  1 . Thus, the second duct  212  and the first duct  211  are arranged to receive respectively a first type of fluid, such as a cleaning material, constituted by solvent and by compressed air, or a second type of fluid, such as a coating material constituted by paint. 
         [0073]    In addition, the first upstream end-piece  262  of the second needle  260  is cylindrical in overall shape, unlike the second upstream end-piece  162  of the valve  100  that is frustoconical in shape. 
         [0074]    Furthermore, the end-piece  232  of the first needle  230  and the end-piece  262  of the second needle  260  have wetted surfaces that are substantially locally tangential to the lines of flow of the fluids, in such a manner as to limit retention of fluid. 
         [0075]    To this end, for example, the valve  200  has a recess  232 . 1  in the shape of a half-torus, which recess is locally tangential to the lines of flow L 211 , as shown in  FIG. 5 . The frustoconical shapes of the first and second upstream end-pieces  132  and  162  are also locally tangential to the lines of flow of the fluids, thereby making it possible to limit fluid retention and to improve rinsing of the soiled surfaces. 
         [0076]    In addition, the valve  200  also has other structural differences relative to the valve  100 . Insofar as these structural differences do not involve operating differences between the valves  100  and  200 , they are not described in the present application. 
         [0077]      FIG. 3  shows a third embodiment of a valve  300  of the invention that is substantially identical to the valve  100  described above with reference to  FIG. 1 . The description of the valve  100  that is given above can be transposed directly to the valve  300 , except for the significant differences mentioned below. An element of the valve  300  that is identical or that corresponds to an element of the valve  100  bears the same numerical reference plus 200. 
         [0078]    This transposition thus defines the valve  300 , a body  301 , an upstream half-body  302 , a downstream half-body  303 , an upstream opening  304 . 1 , a downstream opening  306 . 1 , a first duct  311 , a second duct  312  of axis X 312 , a first needle  330  with a first thrust surface  337 , and first thrust chamber  338 , a recess  340 , a second needle  360  with a second thrust surface  367 , and a second thrust chamber  368  and an internal cavity  370 . 
         [0079]    The valve  300  differs from the valve  100  essentially in that it has a single spring  392  analogous to the second spring  192 . The spring  392  constitutes a resilient member for urging the first needle  330  and the second needle  360  into their respective closed positions in which they close the first duct  311  and the second duct  312 . 
         [0080]    In order to maintain the second needle  360  open, during opening of the first needle  330 , the pressure prevailing in the second thrust chamber  368  must be greater than the pressure prevailing in the first thrust chamber  338 . 
         [0081]    By mounting a single spring  392  instead of two springs  191  and  192 , it is possible to reduce the manufacturing costs and to increase the compactness of the valve  300 . 
         [0082]    Operation of the valve  300  is shown by  FIGS. 6 and 7 . Operation of the valve  100  is substantially identical to operation of the valve  300  that is described below. In order to perform the cleaning stage, the valve  300  is placed in a first opening configuration shown by  FIG. 6 . The first duct  311  and the second duct  312  are opened as a result of the first needle  330  and of the second needle  360  sliding under the effect of the thrusts exerted on the thrust surfaces  337  and  367 . The solvent then flows in the first duct  311  and in the second duct  312 , thereby cleaning the ducts and all of the downstream elements. The flow of solvent is represented by the lines of flow L 311  and L 312 . 
         [0083]    In order to perform the filling stage, the valve  300  is placed in a second opening configuration shown in  FIG. 7 . The first duct  311  is closed by the first needle  330 , while the second duct  312  is opened by moving the second needle  360 . The paint then flows into the second duct  312  towards the reservoir  10 . The flow of paint is represented by the line of flow L 312 . No fluid flows into the first duct  211 . 
         [0084]    When the valve  300  is in a third opening configuration (not shown), the first duct  211  is open, while the second duct  212  is closed. 
         [0085]    Operation of the valve  200  is shown in  FIGS. 4 and 5 . In order to perform the cleaning stage, the valve  200  is placed in a first opening configuration shown in  FIG. 4 . The first duct  211  and the second duct  212  are opened as a result of the first needle  230  and of the second needle  260  sliding under the effect of the thrusts exerted on the thrust surfaces  237  and  267 . The solvent then flows through the first duct  211  and through the second duct  212 , thereby cleaning these ducts and all of the downstream elements. The flow of solvent is represented by the lines of flow L 211  and L 212 . 
         [0086]    In order to perform the filling stage, the valve  200  is placed in a second opening configuration shown in  FIG. 5 . The first duct  211  is opened by moving the first needle  230 , while the second duct  212  is closed by the second needle  260 . Paint then flows into the first duct  211  towards the reservoir  10 . The flow of paint is represented by the line of flow L 211 . No fluid then flows in the second duct  212 . 
         [0087]    When the valve  200  is in a third opening configuration (not shown), the first duct  211  is closed, while the second duct  212  is open. 
         [0088]    In addition to its high compactness, a valve of the invention avoids a mechanically blocked construction that, in the prior art, is made necessary by sealing zones being formed simultaneously for two adjacent ducts. 
         [0089]    In a variant (not shown), the first translation direction of the first needle is parallel to, without being co-linear with, the second translation direction of the second needle. 
         [0090]    In another variant (not shown), the upstream and downstream half-bodies are assembled together by being fastened together by clipping the upstream cylindrical wall onto the downstream cylindrical wall, instead of by screw-fastening as applies to valves  100 ,  200 , and  300 . The assembly clearance resulting from that clip-fastening is taken up by the second spring, because the second spring works in compression and pushes back firstly the downstream half-body and secondly the upstream half-body, via the first needle. 
         [0091]    In yet another variant (not shown) the first needle  130  and the second needle  160  project out of the upstream opening  104 . 1 , instead of being flush therewith as in valves  100 ,  200 , and  300 . This makes it possible to seal off an upstream cavity whenever necessary.