Abstract:
A method for the metered dispensing of a medium from an opening ( 1 ) in a compressible container, particularly from a tube ( 2 ), wherein the medium is to reach a pre-chamber ( 21, 21.1 ) from the tube ( 2 ), wherein the volume of the pre-chamber is to be changed by moving a pressure element ( 8, 26, 29 ), wherein the medium is dispensed from an outlet opening ( 19, 19.1 ) by moving the pressure element ( 8, 26, 29 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a method for the metered dispensing of a medium from an opening in a compressible container, particularly from a tube, and to a device for this purpose. 
         [0002]    Different media are dispensed from a container in a wide variety of ways. For example, devices are known that work according to the suction pump principle. With a suitably sealed plunger, medium is sucked out of the container and, after closure of a nonreturn valve, is dispensed from an outlet opening. This is generally very imprecise and cannot be applied, for example, to tubes or the like. 
         [0003]    The tubes presently available on the market for ointments, pastes, lotions, etc., are metered by the length of the dispensed ribbon of ointment. Particularly in the medical sector, the pack insert leaflet stipulates various ribbon lengths, which are estimated by feel or are measured off using a measurement rod during handling of the tube. This kind of procedure remains inaccurate and is not especially helpful in practice. 
         [0004]    The problem addressed by the present invention is that of providing a method and a device of the abovementioned kind by means of which, for example, it is possible to comply precisely with a prescribed dose, and with which any desired products, irrespective of their viscosity, can be metered and dispensed. 
       SUMMARY OF THE INVENTION 
       [0005]    The problem is solved by the fact that the medium passes from the tube into a pre-chamber whose volume is changed by movement of a pressure element, and the medium is dispensed from an outlet opening by the movement of the pressure element. 
         [0006]    This means that in this case, in contrast to the suction pump principle, the medium is not sucked out, but is instead actively pressed out of the tube into the pre-chamber by the user. In this way, the entire pre-chamber can be filled, such that calibration of the pressure element takes place by means of the latter being pressed back as far as an abutment. In this case, the user also knows that the entire pre-chamber is filled. When he now actuates this pressure element, he is therefore able to press a very precisely metered amount out of the outlet opening, for example a desired ribbon of ointment. 
         [0007]    The pressure element can be designed in various ways. In one illustrative embodiment, it is conceivable for the pressure element to be designed as a linear plunger. In this case a ram, for example, is provided with a plunger face that seals against an inner wall of an axial channel. When this plunger face is acted upon by a medium, the linear plunger retreats and frees a space for receiving the medium. This space is of linear configuration. 
         [0008]    In order to dispense the medium, pressure is applied to the linear plunger, such that the plunger face acts on the medium with pressure. The medium is pressed out through a separate outlet opening. Moreover, this outlet opening was closed by a suitable protective cap during the filling of the pre-chamber. 
         [0009]    To permit precise metering, a suitable scale is provided on the linear plunger, in particular on the ram, and the housing in turn has a suitable marker. On the basis of the position of the scale relative to the marker, it is possible to read off precisely how much medium is dispensed. 
         [0010]    In another illustrative embodiment of the invention, the pressure element is designed as a rotary ring with a slide which is moved in an annular chamber. This annular chamber communicates with the opening of the tube via at least one suitable transverse bore, such that, when pressure is applied to the tube, medium can pass through the transverse bore into the annular chamber. Pressure is also applied to the slide, such that the volume of the annular chamber is increased by rotating the rotary ring and the annular chamber is filled with medium. This preferably takes place between two abutments, which limit the rotation of the rotary ring. 
         [0011]    This rotary ring is also provided with a scale, which permits a metered dispensing of the medium. 
         [0012]    Moreover, a combination of linear movement and rotary movement of a corresponding pressure element also lies within the scope of the invention. In this case, for example, the pressure element can execute a helical movement. 
         [0013]    It is of course conceivable for containers to be already provided with such a device according to the invention at the time of their production. However, it would probably be simpler to use the outer thread of the tubes, which is already present, in order to screw a device according to the invention onto a tube neck. 
         [0014]    For tubes that cannot recover their shape, a nonreturn valve is not required in the device according to the invention. However, there are a large number of containers or tubes in which, when the medium is dispensed, medium may possibly be pressed back into the container by the pressure element. Here, of course, it is more advantageous to have a nonreturn valve. The latter can be made up of a single plastic cone, which is slit for the purpose of producing a valve outlet. However, it is also conceivable to use spring-loaded ball valves, injection-molded flap valves, plate valves, etc. In this respect, no limit is placed on the invention. 
         [0015]    By virtue of the user-friendly handling according to the invention, the metering, particularly from tubes, is more reliable, and such tubes can be used in new fields of application. By employing medically approved materials, the system is of interest especially in the pharmaceutical market, for example for precise metering of pain-relief gels, ointments, skin-sensitive lotions, and aqueous products, etc., or also, for example, for mixing media in the dental sector. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Further advantages, features and details of the invention will become clear from the following description of preferred illustrative embodiments and from the drawing, in which: 
           [0017]      FIG. 1  shows a longitudinal section through a device according to the invention for the metered dispensing of a medium, in the position of use on a pump, of which only part is shown; 
           [0018]      FIG. 2  shows an enlarged detail from another illustrative embodiment of a device according to the invention for the metered dispensing of a medium, similar to  FIG. 1 ; 
           [0019]      FIG. 3  shows a longitudinal section through another illustrative embodiment of a device according to the invention for the metered dispensing of a medium from a tube, with only part of the tube being shown; 
           [0020]      FIG. 4  shows a cross section through the device according to  FIG. 3  along line IV-IV. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    According to  FIG. 1 , a device P 1  according to the invention, for the metered dispensing of a medium from an opening  1  of an only partially depicted tube  2 , has a housing  3  which is screwed via an inner thread  4  onto an outer thread  5  of a neck  6  of the tube  2 . Passing through the housing  3  is an axial channel  7 , in which a linear plunger  8  is arranged to be movable along the double arrow  9 . A plunger face  11  is placed on a ram  10  of the linear plunger  8  inside the axial channel  7  and bears via an annular sealing lip  12  against an inner wall  13  of the axial channel  7 . To further guide the linear plunger  8 , the end of the housing  3  forms an annular opening  14 , which encloses the ram  10 . Outside the axial channel  7 , i.e. after the annular opening  14 , a pressure disk  15  is also fitted on the ram  10 . A scale  16  can also be identified on the ram  10 . 
         [0022]    Near the neck  6 , a nipple  17  is formed integrally on the housing  3  and has a radial bore  18  extending through it. This radial bore  18  leads to an outlet opening  19 , which is closed by means of a protective cap  20  being screwed onto the nipple  17 . 
         [0023]    The function of the present invention is as follows: 
         [0024]    The closure cap (not shown) of a tube  2 , which contains an ointment for example, is unscrewed from the neck  6 , and the device P 1  for the metered dispensing of the ointment from the tube  2  is screwed onto the neck  6 . Ointment is now pressed out of the tube  2  through the opening  1  into the axial channel  7 , with the linear plunger  8  retreating toward the right. In this way, a pre-chamber  21 , of which the volume can be changed, is obtained in front of and in the radial bore  18  and in front of the outlet opening  19 . The volume is initially increased by the ointment being pressed in from the tube  2  and by the retreat of the linear plunger  8 . 
         [0025]    If ointment is now to be dispensed in a metered amount from the outlet opening  19 , the protective cap  20  is removed from the nipple  17 . Thereafter, pressure is applied to the linear plunger  8  by pressing on the pressure disk  15 , such that the plunger face  11  reduces the volume of the pre-chamber  21 . In this way, ointment is pressed through the radial bore  18  and out of the outlet opening, and the scale  16  allows the amount dispensed to be precisely monitored. 
         [0026]    The annular opening  14  serves as an abutment for the plunger face  11  and also for the pressure disk  15 . The movement of the linear plunger  8  is limited in this way. 
         [0027]    In the case of metal tubes, for example aluminum tubes, or tubes made of similar materials, i.e. tubes or containers which, after being squeezed or pressed, remain in the squeezed position, that is to say do not return to the original shape, the medium in the tube itself constitutes a barrier against return flow. 
         [0028]    In tubes with a return suction or return flow effect, for example in plastic tubes with their own restoring force of the tube wall, it would probably be advisable, however, to fit a nonreturn valve  22  as indicated in  FIG. 2 . Such a valve is preferably made of a soft material, e.g. LLDPE, in order to utilize the residual stress of the material of the valve wall thickness as closure force. For a valve outlet  23 , a conical valve wall  24  is slit in order thereby to permit opening and closing. To reliably maintain the metering function, this nonreturn valve  22  is preferably placed between the opening  1  and the radial bore  18 . 
         [0029]    In the further illustrative embodiment of a device P 3  according to the invention for the metered dispensing of a medium from a tube  2  according to  FIGS. 3 and 4 , a housing  3 . 1  is likewise screwed onto the tube neck  6 . This housing  3 . 1  also has an axial channel  7 . 1  running through it, but in this case the axial channel  7 . 1  extends axially from the opening  1  as far as an outlet opening  19 . 1 . This outlet opening  19 . 1  is again closed by the protective cap  20 . 
         [0030]    In this illustrative embodiment, a pre-chamber  21 . 1  is not part of the axial channel, but is designed as a separate annular chamber that encircles the axial channel  7 . 1  and communicates with the latter via at least one transverse bore  25 . 
         [0031]    The pre-chamber  21 . 1  is closed off from the outside by a rotary ring  26 , and this rotary ring  26 , together with corresponding housing walls, forms at least two annular seals  27 . 1  and  27 . 2 . 
         [0032]    According to  FIG. 4 , the rotary ring  26 , which can be rotated according to the double arrow  28 , is assigned a slide  29 , which extends more or less radially away from the rotary ring  26  and bears on an annular wall  30  of the housing  3 . 1 . 
         [0033]    In cooperation with the slide  29 , the rotation movement of the rotary ring  26  is delimited by two abutments  31  and  32 , which protrude from the annular wall  30  near the transverse bore  25 . The abutment  21  reaches as far as an inner wall  33  of the rotary ring  26 , while the other abutment  32  engages only a short distance into the rotation path of the slide  29 , such that the latter cannot travel past this abutment  32 . However, toward the inner wall  33  of the rotary ring  26 , it leaves free a through-flow opening  34  through which medium can flow and exert pressure on the slide  26 , such that here too a pre-chamber  21 . 1  of variable volume is obtained. 
         [0034]    Here too, there is a scale (not shown) present on the outside of the rotary ring  26 , which scale can interact for example with a marker (not shown) on the housing  3 . 1 . 
         [0035]    The function of this illustrative embodiment of a device P 3  according to the invention is similar to that according to  FIG. 1 . However, the pre-chamber does not fill linearly, but circularly. In other words, the medium that is to be dispensed is pressed out of the tube  2  and, with the outlet opening  19 . 1  closed, passes through the transverse bore  25  into the pre-chamber  21 . 1 . There, this medium presses on the slide  29 , such that the rotary ring  26  is rotated, until the slide  29  reaches the abutment  31 . 
         [0036]    To dispense the medium, the protective cap  20  is again removed from the outlet opening  29 . 1 . The rotary ring  26  is then rotated counter to the filling direction, such that pressure is exerted by the slide  29  on the medium in the pre-chamber  21 . 1 . This medium flows through the through-flow opening  34 , the transverse bore  25  and the axial channel  7 . 1  and out of the outlet opening  19 . 1 . 
         [0037]    When the term compressible is used elsewhere in this text, it is not to be understood as referring only to a container whose own wall is deformable, and instead it also includes the known two-chamber cans with a squeezable inner pouch. It also includes containers which have a rigid wall but whose volume can be modified by plungers, membranes or the like. It is important only that the medium can be dispensed actively from the container by an action of the user.