Abstract:
An air filtration device for the vent of a body of a pump used to fit a liquid or semi-liquid product distributor, the device including a filter membrane through which the product may be discharged from opening. The free edge of the membrane is connected to a support element which is tightly fixed on the opening.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of pending International patent application PCT/FR2006/001275 filed on Jun. 6, 2006 which designates the United States and claims priority from French patent application 0505940 filed on Jun. 10, 2005, the content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to an air filtration device for a pump fitted on a liquid or semi-liquid product dispenser. 
     BACKGROUND OF THE INVENTION 
     Pharmaceutical and cosmetic products and perfume dispensers generally comprise a pump mounted on a container and activated by a push-button so as to deliver the product. 
     When the delivery is completed, it is necessary to equalize the loss of the discharged product volume with an equivalent volume of air which is taken from the outside, because of the depression inside the container. This air intake is automatically carried out first through the passages provided therefor inside the pump body, then via a so-called vent orifice provided through the body wall and opening inside the container. The pressure inside the container thus remains identical to that of the atmosphere outside. 
     However, it is necessary to provide for the filtration of the incoming air flow, if only to preserve the proprieties of the product and prevent the risks of pollution or bacterial or fungal contamination, more particularly for the packaging of pharmaceutical or cosmetic products. 
     The existing filtration devices are generally composed of a ring made of a filtering material mounted with a radial tightening around the pump body and covering the vent orifice. 
     However, this solution is not satisfactory since the ring increases the outer diameter of the pump body which involves assembling problems in the container neck and tightness problems. 
     Besides, the mechanical resistance of this ring is not reliable over time, which entails risks of accidental pollution. As a matter of fact, the contact area between the pump body and the filter must be perfectly air tight, so as to force it through the ring. 
     In addition, an excessive tightening of the ring on the pump body may entail malfunctions of the later. 
     SUMMARY OF THE INVENTION 
     The aim of this invention is to solve the problems of the prior art. This aim is reached according to the invention using a device of the preceding type, characterized in that it comprises a filter membrane through which said vent orifice may open and the free edge of which is connected to a supporting element tightly mounted on said orifice. 
     According to an advantageous characteristic, the pump body has a flat section extending immediately around the vent orifice. 
     According to another characteristic, the porosity of said membrane is comprised between 0.05 and 0.5 micrometers. 
     According to a first varying embodiment, said supporting element is composed of a peripheral area of said membrane located radially beyond said vent and which is directly welded or stuck onto the edges of said orifice. 
     According to another variation, the free edge of said membrane is engaged into an over-molded frame. 
     Preferably, said frame is integral with said supporting element. 
     Still according to this variation, said supporting element is shaped like a sleeve, the outer diameter of which is substantially equal to the inner diameter of said orifice in which it is intended to be introduced, like a plug. 
     Advantageously, said sleeve has a tapered end in order to facilitate its introduction into the orifice. 
     Besides, said frame has a shoulder coming into raised contact with the wall of the pump body in order to position the membrane with respect to said orifice. 
     According to still another characteristic, said membrane is positioned inside said orifice. 
     The device according to the invention ensures an efficient filtration of the incoming air while having minimum overall dimensions on the pump body and being localized close to the vent orifice. 
     The behavior of the device on the pump body is enhanced with respect to prior devices and the tightness is reinforced. 
     Besides, the invention results in a significant gain of filtering material because of the small surface used. 
     In addition, this device can be applied to various pump calibers and relatively wide ranges of products viscosity (from liquid to pasty) without it being necessary to modify or adapt to dimensions of the membrane. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the invention will become evident when reading the description which follows and making reference to the appended drawings in which: 
         FIG. 1  shows a general view with an axial section of a pump on a container showing the passages for the air intake; 
         FIGS. 2A and 2B  show partial, respectively sectional and profile views of an embodiment of the device of the invention mounted on a pump body; 
         FIG. 3  shows a cross-sectional view of the embodiment of  FIGS. 2A ,  2 B; 
         FIG. 4  shows a cross-sectional top view of another embodiment of the device of the invention applied to a pump body. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The dispenser shown in  FIG. 1  comprises a pump P mounted on a neck C of container, where it is crimped with a ring B. 
     The body K of the pump P is composed of a cylindrical-conical enclosure which has a piston mechanism topped with a spray tube T. The body K is provided with a vent orifice E provided through its side wall and positioned above the level of the upper edge of the neck C. 
     When the restitution phase is completed, the depression created in the container causes the suction of an equalizing air volume which is taken from the outside through the passage defined inside the body K, at the upper part between the tube T and the inner wall of the body then through the vent orifice E and eventually at the lower part between the outer wall of the body and the inner wall of the neck C, as shown with the marked path on  FIG. 1 . 
     The device of the invention aims at filtering the air coming into the container during the return to equilibrium of pressures inside and outside the container. Therefore, the device comprises a filter membrane  1  through which the orifice E is likely to open and the free edge of which is connected to the supporting element tightly fitted on said orifice. 
     As air goes from inside the body to the inner volume of the container, the membrane  1  is positioned either outside the body K ( FIG. 4 ) or at least partially inside the orifice E ( FIG. 2A ). 
     The porosity of membrane  1  is adapted to the filtration of air and is comprised between 0.05 and 0.5 micrometers. 
     In order to facilitate the fixing of the device, the body K of the pump has a flat section M extending immediately around the vent orifice E. 
     In the embodiment of  FIGS. 2A ,  2 B and  3 , the free edge  10  of said membrane  1  is engaged into a frame  2  or it is trapped by the over-molding and defines a central channel  20  through which the filtering surface of the membrane is placed. 
     The frame  2  is integral with the supporting element. 
     Here the supporting element is shaped like a sleeve  21 , the outer diameter of which is substantially equal to the inner diameter of the orifice E in which it is intended to be fitted, like a plug as shown in  FIGS. 2A and 2B . The fixing is then ensured by means of a simple radial tightening, if need be reinforced by gluing or welding. 
     Such fixing makes it possible to hold the device in the orifice E of the body K, even during the suction phase when taking air in. 
     As shown in  FIG. 3 , the sleeve  21  has a tapered end  22  to facilitate its introduction into the orifice E. 
     The frame  2  has a projecting shoulder  23  coming into rest contact with the wall of the body K of the pump in order to limit the driving of the device and correctly position the membrane  1  with respect to the orifice E. 
     In the variation of  FIG. 2A , the length of the sleeve  21  is greater than or equal to the thickness of the body K wall and the membrane  1  is positioned inside the orifice E, in the thickness of the body K wall. 
     However, it is possible according to a variation of to provide that the membrane  1  covers the orifice E outside the body of the pump. 
     In the embodiment of  FIG. 4 , the supporting element is composed of a peripheral area  11  of the membrane  1  located radially beyond the orifice E and which is welded or glued directly on the flat section M up to the edges of said orifice. In this case, the central part of the membrane  1  covers the orifice E.