Abstract:
The spray assembly of a dispensing device is arranged together with a mixing assembly inside a mixing and spray head, the mixing assembly being arranged before the swirl chamber of the spray assembly, and the mixing and spray head, which forms a unit, being removably attached to a multicomponent dispensing appliance. The result is a more homogeneous spray action, on one hand, and an easy replacement of the head, on the other hand.

Description:
This application is the National Phase of PCT/CH2007/000193, filed Apr. 23, 2007, which claims priority to Switzerland Application No. 00803/06, filed May 17, 2006, the disclosures of which are hereby incorporated by reference in their entirety. 
     The present invention relates to a dispensing device with a spray assembly according to the preamble of claim  1 . A device of this kind is e.g. known from U.S. Pat. No. 4,260,110, which patent mainly relates to the design of a spray nozzle, however. This patent specification only discloses dispensing devices having a spray nozzle for a single component. 
     BACKGROUND OF THE INVENTION 
     For certain medical applications, however, two-component materials are stored in double syringes or double cartridges, mixed by means of static mixers and dispensed using different application instruments. For large surface dispensing or when a distribution of the mixed materials by means of an applicator is not possible, a spraying system has to be used. In conventional spray assemblies, the two-component materials are only mixed to a limited extent or compressed air is additionally required which in certain operations leads to undesirable aerosol formation and does not always ensure a homogeneous distribution of the two components on the sprayed surface. 
     SUMMARY OF THE INVENTION 
     On this background, it is the object of the present invention to provide a dispensing device by means of which two or more components are homogenously mixed prior to their entry into the spray nozzle. In addition, as the components harden after having been mixed and sprayed, the mixing and spray assembly should be exchangeable in the simplest possible manner. This is accomplished by the dispensing device according to claim  1 . 
     The invention will be explained in more detail hereinafter with reference to drawings of exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  show a first exemplary embodiment of a dispensing device according to the invention in a perspective view, 
         FIG. 2  shows an enlarged detail of  FIG. 1 , 
         FIG. 3  shows the mixing and spray head of  FIG. 2  in the assembled condition, 
         FIG. 4A  shows a section according to line IV-IV in  FIG. 3 , 
         FIG. 4B  shows a partial view of an embodiment variant of the mixing and spray piece of  FIG. 4A  with a compressed air inlet, 
         FIG. 5  shows a section according to line V-V in  FIG. 4 , 
         FIG. 6  shows a section according to line VI-VI in  FIG. 4 , 
         FIG. 7  shows a section according to line VII-VII in  FIG. 6 , 
         FIG. 8  shows a second exemplary embodiment of a dispensing device according to the invention in a perspective view, 
         FIG. 9  shows a section through the assembled mixing and spray head of  FIG. 8 , and 
         FIG. 10  shows a section according to line X-X in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     Dispensing device  1  according to  FIGS. 1A and 1B  includes a double syringe  2  and a mixing and spray head  3  that is attachable thereto. In a known manner, the double syringe comprises two storage containers  4  and  5  having equal volumes or equal cross-sectional areas, respectively, or cross-sectional areas whose ratio is different from 1:1. The two components are dispensed by means of a double plunger  6 . 
     Mixing and spray head  3 , hereinafter called “head” for the  10  sake of simplicity, is essentially composed of three parts, namely a transfer housing  7  and a mixing and spray piece  8  that may be connected to the transfer housing by snap means, welding, cementing, a screw connection or by means of a bayonet coupling. 
     Basically, the head may be coupled to the dispensing appliance in different ways, for example by bayonet coupling means or by a screw connection. Advantageously, however, the head is simply plugged onto the dispensing appliance and easily removable therefrom by a connection as it is described in Swiss patent application no. 00453/06 to the applicant of the present invention. To this end, fastening area  9  on the outlet side of the dispensing appliance has an outlet flange  10  on which the two individual outlets  11  and  12  are arranged. Each outlet  11  and  12  has an essentially diametrically arranged, outwardly directed ridge  13  respectively  14  that tapers from outlet flange  10  toward the outlet. Each ridge has a saddle portion  15  respectively  16  that ends at a distance from the outlet flange and is followed there by a snap nose  17  respectively  18 , the snap noses engaging in recesses  19  and  20  in transfer housing  7 , see  FIG. 4A . 
     The two saddle portions  15  and  16  have the same configuration, but saddle portion  15  has an end portion  21  on the outlet side while saddle portion  16  has none. The presence or absence of end portion  21  constitutes a coding means ensuring that the head can only be attached in an unequivocal orientation. Furthermore, on both sides of their connecting plane, the two outlets are provided with clamping guides  22 . Additionally, outlet flange  10  has a visual coding nose  23  that serves as an orientation aid for the head, the latter having a corresponding orientation nose  24 . 
     In  FIG. 2 , a head  3  consisting of two component parts is illustrated where mixing and spray piece  8  is fastened to transfer housing  7  while the end of the latter forms rear chamber bottom wall  44  of the mixing and swirl chambers. At its outlet side end, transfer housing  7  has a distributor socket  25  in which four distributor outlets  26  and two positioning grooves  27  are arranged. In the area of corrugation  28 , the housing is compressible in order to disengage snap noses  17  and  18  from recesses  19  and  20 , thereby allowing to withdraw the head. 
     As follows from  FIG. 4A , two longitudinal bores  29  and  30  are arranged in the distributor socket which communicate with transversal bores  31  and  32 , these transversal bores leading to distributor outlets  26 . The coding and orientation noses allow plugging the head onto the dispensing appliance in such a manner that longitudinal bores  29  and  30  are in line with outlets  11  and  12  of the dispensing appliance. 
     As appears in  FIG. 2 , longitudinal feed passages  33  extend from ends  26  of the transversal bores. In  FIG. 4A  it is shown that coupling portion  34  of mixing and spray piece  8  has a circumferential groove  35  for receiving a corresponding collar  35 A on the transfer housing. Housing portion  34  further comprises two positioning cams  36  which engage in corresponding positioning grooves  27 . Closure  37  of mixing and spray piece  8  has four longitudinal channels  38  opening into an annular mixing chamber  39  from where four feed passages  40  lead to a concentric swirl chamber  41  from which spray outlet  42  leads to the exterior. As shown in  FIG. 6 , the longitudinal feed passages  40  open out tangentially into the swirl chamber  41 . 
     In  FIG. 4B , an embodiment variant is illustrated in which a compressed air inlet  60  is arranged on end plate  50  of mixing and spray piece  61  in order to achieve a better spray action in certain cases. The other parts of the head are the same. 
     In  FIG. 6  it is visible that feed passages  40  and feed ducts  43  do not form the same angle with respect to the mixing chamber and are offset from one another. Moreover, the feed passages and the feed ducts and the swirl and mixing chambers, respectively, do not have to be arranged in the same plane with respect to the longitudinal axis of the head. 
     In  FIG. 7  it is apparent that bottom wall  44  of the mixing chamber is plane while at the top, i.e. in closure  37 , serrated mixing elements  45  are arranged which produce turbulences in order to mix the two components before they reach the swirl chamber from where they are sprayed through the spray outlet. 
     As mentioned in the introduction, the present invention essentially aims to provide a mixing assembly before the spray assembly, more particularly before the swirl chamber, in order to achieve an efficient mixture of the components prior to the actual spraying procedure. Instead of providing an annular, concentric mixing chamber having serrated mixing elements, it is also possible according to  FIGS. 8 to 10  to provide a mixing assembly comprising a static mixing element as it is known per se. 
     Dispensing device  46  according to  FIG. 8  includes the same dispensing appliance  2  and the same fastening area as in the previous example. The fastening area of transfer housing  47  is the same as in the previous exemplary embodiment whereas mixer socket  48  is configured for receiving a mixing assembly  49  in its interior and fastening means  50 ,  51  on its exterior in order to attach mixing and spray piece  58  to transfer housing  47 , thereby forming mixing and spray head  55 . 
     Mixing assembly  49  with mixing element  52  is fastened in the interior of closure  53  of mixing and spray piece  58  and forms a unit with the latter. Fastening means  50 ,  51  for the attachment of the mixing and spray piece to transfer housing  47  may be snap, bayonet, or screw connections, or it may be fastened by ultrasonic welding or cementing. 
     As follows from  FIG. 10 , closure  53  of the head has feed passages  54  arranged therein, e.g. three of them, which lead to a swirl chamber  56  in the same manner as in the previous example from where spray outlet  57  leads to the exterior. The long feed passages  54  open out tangentially into the swirl chamber  56 . 
     Based on the two exemplary embodiments of a mixing chamber or of a mixing assembly, respectively, other possibilities of mixing assemblies can be designed by one skilled in the art by which the components, whose number may also be greater than two, are efficiently mixed shortly before the swirl chamber prior to being sprayed through the swirl chamber and the spray outlet.