Abstract:
A discharger for a flowable medium, having a pumping device with a pumping chamber which is closed off on one side by a longitudinally movable piston, is provided. 
     The pumping chamber on the piston side is hermetically sealed against an environmental atmosphere outside the discharger by a gas-impermeable and at least partially flexible diaphragm, and the diaphragm, in its marginal region, is fixedly connected to a housing of the discharger. 
     The discharger is used for high sealing requirements against the ingress of impurities.

Description:
FIELD OF THE INVENTION 
     The invention relates to a discharger for a flowable medium, having a pumping device comprising a pumping chamber which is closed off on one side by a longitudinally movable piston. 
     BACKGROUND OF THE INVENTION 
     Dischargers of the generic type serve for the discharge of cosmetic or pharmaceutical mediums. These are conveyed from a medium store by actuation of the pump and are discharged into an environment through a discharge opening. The pumping process is generally triggered by a manually operable actuating device, by means of which a piston in the pump is displaced. As a result, a discharge pressure is generated which forces the medium in the pumping chamber out of the discharger through the discharge opening. 
     It is regarded as a drawback with known dischargers that the sealing of the pumping chamber against the environment, especially in the region of the actuating device, is frequently unsatisfactory. This results in an unwanted escape of medium from the discharger and an unwanted ingress of impurities into the discharger. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to improve the dischargers known from the prior art, especially with regard to the sealing of the pumping chamber. 
     This object is achieved by a discharger of the generic type in which the pumping chamber, on the piston side, is hermetically sealed against an environmental atmosphere outside the discharger by means of a gas-impermeable and at least partially flexible diaphragm, the diaphragm, in its marginal region, being fixedly connected to a housing of the discharger. 
     The diaphragm is preferably configured as a thin plastics layer. It is elastic in order that, when clamped fixedly to the housing by its marginal region, it can still follow the stroke movement of an actuating device and of the piston. Compared with the dischargers known from the prior art, in which the actuating device and the piston are mounted relative to the housing of the discharger by means of sliding guides, the housing-fixed clamping guarantees a secure protection from impurities, especially from microbiological impurities. As a result of the stationary clamping, a hermetic seal, in contrast to sliding and usually play-afflicted sealing surfaces, is obtainable. The marginal region is preferably clamped in place by latching or wedging means by which the marginal region is forced against a housing-side bearing surface, so that the sealing effect is given in this clamping region also. A thickening of the diaphragm in the marginal region additionally allows a stiffening to be achieved which deters the diaphragm from sliding out of the latching or locking means. As an alternative to latching and clamping means, embodiments having a bonded fastening of the marginal region of the diaphragm can also be expedient. Moreover, embodiments of the invention are also covered in which the diaphragm is integrally connected to the housing. This can be achieved by using the same material for the housing and the diaphragm, with markedly reduced wall thickness in the region of the diaphragm. Alternatively, the integrality is also obtainable with different materials, however, using a two-step injection process. As a material combination, PP for the housing and TPE for the diaphragm, for example, is an option. The fixed connection of the diaphragm to the housing does not need to be made in the region of the outer surface. By housing should be understood, in connection with the invention, housing-fixed components. In particular, the housing also comprises the inner wall of the pumping chamber, which does not need to be configured in one piece with an outer surface of the housing. 
     In one refinement of the invention, the diaphragm is connected to an actuating device operatively connected to the piston. Particular preference is for a one-piece design. The marginal region of the diaphragm is here preferably secured to the outer wall of the housing, for example wedged in place in an outward-facing groove on the housing surface. The connection to the actuating device is preferably made integrally, so that the actuating device is produced from the same material as the diaphragm and acquires the necessary stability through a corresponding greater material thickness. Alternatively thereto, the diaphragm can also, however, be provided as a separate component, which fully covers the actuating device in the manner of a protective cover. 
     In one refinement of the invention, the diaphragm is connected to the piston. Particular preference is for a one-piece design. In this refinement, the pumping chamber is directly closed off by the elastic diaphragm, so that the change in volume of the pumping chamber in the course of the actuation is obtained via the elastic deformation of this diaphragm. The diaphragm is in this case preferably fastened to the pumping chamber wall. One advantage with such an embodiment is that even impurities which infiltrate the discharger at places other than at the actuating device cannot get into the pumping chamber. In a particularly advantageous embodiment of this refinement, the marginal region of such a diaphragm simultaneously forms the bearing surface for a restoring spring of the actuating device, so that the restoring spring, apart from the task of forcing the actuating device back into the initial position, also fulfills the task of pressing the diaphragm against its bearing surface, so that a very good seal is obtained in the marginal region of the diaphragm. 
     In one refinement of the invention, the diaphragm is provided as a separate component between the piston and the pumping chamber. 
     In one refinement of the invention, the piston is longitudinally movable in a piston direction which forms a right angle with a principal direction of extent of the discharger. In such dischargers in which the pumping and actuating direction runs perpendicular to a principal direction of extent of the discharger, the invention can be realized very simply and inexpensively. This is founded, above all, in the fact that the diaphragm is not disposed on a side of the pumping chamber which faces a medium store and does not therefore, as a result of its position, hinder the supply of the medium into the pumping chamber. 
     In one refinement of the invention, an inlet duct and/or an outlet duct are disposed in the pumping chamber on the side facing away from the piston. This allows a particularly advantageous supply and evacuation of the medium into and out of the pumping chamber, especially in such embodiments in which the diaphragm is disposed separately or as part of the piston in a prescriptively correct manner within the pumping chamber. In these embodiments in which the diaphragm is disposed in the pumping chamber, the problem that a supply of medium at a lateral pumping chamber wall can only be realized with difficulty is thereby solved. 
     Embodiments are particularly preferred in which, on the piston side, an actuating element is provided which, depending on the piston position, is operatively connected to the inlet duct or the outlet duct, the operative connection comprising, in particular, an opening or closing of the inlet duct or of the outlet duct. The purpose of such a configuration lies in the fact that the piston, depending on its position, can prevent a supply or evacuation of the medium into and out of the pumping chamber. This is advantageous above all on the basis that, in dischargers according to the invention in which the piston or a piston-fixed diaphragm is fixed to the side wall of the pumping chamber, a normal controlling of the outflow and inflow via inlets or outlets provided on a lateral pumping chamber wall is not practicable. 
     A particularly simple embodiment of this refinement provides that a closing pin extends in the motional direction of the piston, starting from the piston, into the piston chamber and, from a defined stroke position, by passing into the medium inlet, causes the pumping chamber to be decoupled from the medium store. From this stroke position, an onward movement of the piston produces an increase in pressure in the pumping chamber, giving rise to a discharge process. 
     Alternatively or additionally, the actuating element can also be used, from a second defined stroke position, to reconnect the pumping chamber to the medium store in order to provoke an abrupt drop in pressure in the pumping chamber. Such an embodiment is expedient with regard to the so-called priming, i.e. the initial filling of the pumping chamber with medium. The piston is here pushed fully into the pumping chamber until it reaches the second stroke position. In this stroke position, the compressed air escapes from the pumping chamber into the medium store or into the environment, so that, upon the return stroke, an underpressure is created which provokes the initial filling of the pumping chamber. 
     This is preferably realized in the course of the activation through an air outlet device for evacuating the air present in the pumping chamber, the air outlet device being disposed and configured in such a way that, upon a piston movement which reduces the volume of the pumping chamber, it is opened in a second stroke position situated beyond a first stroke position in which, in normal operation, the fluid pressure of the medium in the pumping chamber causes an outlet valve of the discharger to open. 
     In such a discharger, upon activation, the piston is forced into the air-filled pumping chamber until the second stroke position is reached, in which the air outlet device is opened by the piston. The compressed air is then able to escape through the air outlet device, for example to the outside or into the medium container. In the course of the return stroke, the air outlet device is reclosed directly or indirectly by the piston, so that the air cannot get back into the pumping chamber. Instead, during the return stroke, according to the embodiment of the pumping device, medium is sucked directly out of the medium container into the pumping chamber, or an underpressure is generated in the pumping chamber which, when a medium duct from the medium container to the pumping chamber is opened up by the piston, leads abruptly to the pumping chamber being filled with the medium. In the following actuations of the pumping device in normal operation, the second stroke position is not reached, or is only reached after the outlet valve of the discharger has been opened and after an associated discharge process, so that in the second stroke position no medium or only a small amount of the medium escapes through the air outlet device. The air outlet device can additionally boast a filter which, in normal operation, prevents an unwanted escape of fluid medium through the air outlet opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and features of the invention emerge from the claims and the following description of preferred illustrative embodiments of the invention, which are represented with reference to the drawings in which: 
         FIG. 1  shows a first embodiment of a discharger according to the invention in a sectioned representation, 
         FIGS. 2   a  and  2   b  show a second embodiment of a discharger according to the invention in sectioned representations of two actuation states, 
         FIG. 3   a  to  3   d  show a third embodiment of a discharger according to the invention in sectioned representations of four activation states of the discharger, and 
         FIG. 4   a  to  4   d  show a fourth embodiment of a discharger according to the invention in sectioned representations of four activation states. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a first embodiment of a discharger according to the invention. This discharger is designed for applying a medium into an eye. As the basic principal components, it has a housing  10  comprising an actuating device  30 , a pumping device  40  disposed in the housing, and a discharge valve unit  60 . By means of an internal thread  12  provided on the inner wall of the housing, a medium container  80 , secured by latching bosses (not described in detail) against release, is connected to the discharger. 
     The connection of the medium container  80  to a pumping chamber  46  of the pumping device  40  is established by an inlet duct  44 , which runs into the medium container  80  within an opening mandrel  48 . By means of this opening mandrel  48 , a membrane  82  of the medium container  80  is pierced. 
     The inlet duct  44  leads into a pumping chamber  46 , which is closed off on one side by a piston  50 . On that side of the pumping chamber  46  which is facing away from the piston  50 , an outlet duct  56  is provided, which leads to the discharge valve unit  60 . The piston  50  is fixedly connected by a latching connection to a main shaft  32  of the actuating device  30 . At the outer end of the main shaft  32 , this merges integrally into the roughly semispherical elastic diaphragm  34 . This diaphragm  34  merges at its outer end into a marginal region  36  of enlarged wall thickness, which is fixed in a housing-fixed position by a circumferential latching web  14  molded integrally onto the housing  10 . The actuating device  30  is forced constantly outward by a restoring spring  38 , whereby the piston  50  is drawn into a stroke limit position with the pumping chamber  46  at maximum volume. In one embodiment (not represented), a separate restoring spring is avoided by the fact that the elastic diaphragm itself applies the restoring forces. 
     The discharge valve unit  60  has a discharge sleeve  62  which is integrally molded onto the housing  10  and within which there is disposed a closing pin  64 . If—as in the represented state—no overpressure is present in the pumping chamber  46  and in the discharge valve unit  60  connected to the pumping chamber  46  by the outlet duct  56 , the closing pin  64  is forced by a closing spring  66  into the discharge sleeve  62 , so that a discharge opening  68  at the distal end of the discharge sleeve  62  is sealed by the closing pin  64 . On its side facing away from the discharge opening  68 , the closing pin  64  has a particularly large, collar-shaped pressure plate  70 , adjoined on the outside by a circumferential bearing web  72  which bears against the pumping device  40 . The pressure plate  70  itself is spaced apart from the pumping device  40 , the air-filled interspace being outwardly sealed by means of the bearing web  72 . 
     When, following the activation of the discharger, the actuating device  30 , in normal operation, is forced down in a pumping direction  90  by the filling of the pumping chamber  46  with the medium from the medium container  80 , the diaphragm  34  deforms, the marginal region  36  remaining clamped to the housing  10 . After about a third of the stroke travel, the connection of the inlet duct  44  to the pumping chamber  46  is broken by the piston  50 . In the course of the further piston movement, the fluid pressure of the medium present in the pumping chamber  46 , in the outlet duct  56  and in the discharge valve unit  60  is increased to the point where the pressure upon the pressure plate  70  is sufficiently high to displace the closing pin  64  counter to the spring force of the closing spring  66 . Owing to the size of the pressure plate  70 , a comparatively small pressure is sufficient for this purpose. The pressure plate  70  is hereupon elastically deformed by the pressure. 
     As soon as the closing pin  64  consequently has opened up the discharge opening  68 , the medium escapes in a principal direction of extent  92  of the discharger through the discharge opening  68 , whereupon, owing to the low pressure, it forms no spray jet, but instead drips are formed at the discharge opening  68 . 
     One advantage with the discharger represented in  FIG. 1  and described above is the structure, which allows comfortable and secure handling. 
     Particularly advantageous is the inventive hermetic encapsulation of the pumping chamber  46  from an external atmosphere as a result of the particular design of the actuating device  30  with the deformable diaphragm  34 , which actively prevents contamination of the medium in the pumping chamber  46 . Given the orthogonal design of the discharger, this encapsulation can be realized particularly easily, since, with respect to the arrangement, it does not come into conflict with a supply line from the medium container  80 . 
     The hermetic encapsulation prevents both the escape into the environment of medium which makes its way past the piston  50  out of the pumping chamber  46  in the direction of the actuating device  30 . Above all, however, it additionally prevents the ingress of impurities, especially microbacterial impurities. 
       FIGS. 2   a  and  2   b  show a second embodiment of a discharger according to the invention in two different states,  FIG. 2   a  showing a state prior to actuation of an actuating device  130  and  FIG. 2   b  showing a state during the actuation of the actuating device  130 . 
     The structure of the discharger of  FIGS. 2   a  and  2   b  is in this case similar to the structure of the embodiment of  FIG. 1 . Once again, the discharger has a housing  110  comprising the actuating device  130  and a discharge valve unit  160 . In the housing  110  there is a pumping device  140  having a piston  150 , a pumping direction  190  of the piston, which simultaneously constitutes the motional direction of the actuating device  130 , running perpendicular to a principal direction of extent  192  of the discharger, which corresponds to the discharge direction of the medium. 
     The differences relative to the embodiment of  FIG. 1  lie, in particular, in the design of the piston  150  and the design of the discharge valve unit  160 . 
     The piston  150  is configured as a flexible diaphragm, which, in a central region  152 , is fixedly connected to the actuating device  130 . The diaphragm is secured in the pumping device by its outer marginal region  154  and thus seals a thereby delimited pumping chamber  146  against the actuating device  130  and against impurities infiltrating the latter. Since the piston  150 , because of the securement in the marginal region, is not suitable for closing off in the course of the piston stroke an inlet duct for medium, which inlet duct enters in the wall region of the pumping chamber  146 , the inlet duct  144  is arranged such that it opens out on the end face, situated opposite the piston  150 , of the pumping chamber  146 . The piston  150  is shaped in its central region  152  such that it closes off this inlet duct  144  in the course of the actuation and thereby allows the build-up of the fluid pressure necessary for the discharge process. 
     The design of the discharge valve unit  160  comprises a closing pin  164 , which is molded integrally onto the housing  110 . Around the closing pin  164 , on the surface of the housing, a circular groove  174  is provided, in which a marginal region  176  of an elastic discharge sleeve  162  is inserted. In dependence on the fluid pressure in a pressure chamber  170  between the housing  110  and the discharge sleeve  162 , the discharge valve unit  160  opens by virtue of the opening-up of a discharge opening  168 . The closed state is represented in  FIG. 2   a . The open state is represented in  FIG. 2   b.    
     If, starting from the initial state of  FIG. 2   a , the actuating device  130  is pressed in in the pumping direction  190 , the piston  150  is also thereby forced into the pumping chamber  146 , the marginal region  154  of the piston remaining immovably clamped in a housing-fixed manner and preventing impurities from infiltrating the pumping chamber  146 . The central region  152  of the piston  150  is forced into the inlet duct  144  and closes this off against the pumping chamber  146 . From a stroke position in which the inlet duct  144  is closed off, the progressive stroke movement of the piston leads to an increase in fluid pressure in the pumping chamber  146 , the outlet duct and the pressure chamber  170 . This increase in fluid pressure leads, in the manner described above, to an opening of the discharge valve unit  160 , as represented in  FIG. 2   b . In a non-represented manner, the discharge sleeve returns, following discharge of the medium, into its original position and elastically relaxed original shape. The actuating device  130  is forced back into the original position by a restoring spring  138 , an underpressure arising in the pumping chamber  146 . Only once the central region  152  of the piston  150  opens up the inlet duct  144  again can medium again be sucked out of a medium container  180  into the pumping chamber  146  as a result of the created underpressure. 
       FIG. 3   a  to  3   d  show a third embodiment of a discharger according to the invention. 
     With respect to the basic structure with an actuating direction and a pumping direction  290  orthogonal to a principal direction of extent  292  of the discharger, this embodiment corresponds to the embodiments of  FIGS. 1 ,  2   a  and  2   b . With respect to the hermetic sealing of a pumping chamber  246  by means of a semispherical diaphragm  234  which is constructed in one piece with an actuating device  230 , it corresponds to the embodiment of  FIG. 1 . The peculiarity of this embodiment lies in a special design of the pumping device  240  with regard to the activation. In addition to a first piston  250  which is fixedly connected to the hermetically sealing actuating device  230 , this third embodiment has an opposed piston  260 , which is disposed on the opposite side of the pumping chamber  246 . This is pressurized by a spring force of an opposed piston spring  264  in the direction of an upper limit position and of the first piston  250 . The opposed piston  260  is guided by means of an opposed piston guide  262 , which limits its freedom of movement between the upper limit position, in which an outlet duct  256 , up to a discharge opening  268 , is separated from the pumping chamber  246 , and a lower limit position in which the outlet duct  256  is connected to the pumping chamber  246 . This structure allows a particularly advantageous ventilation of the pumping chamber  246  in the course of the activation. This is described below with reference to the process of  FIG. 3   a  to  3   d.    
       FIG. 3   a  shows the delivery state in which the pumping chamber  246  is fully filled with air. The first piston  250  is forced by a restoring spring  238  into its upper limit position. The opposed piston  260  is forced by the opposed piston spring  264  likewise into its upper limit position, so that the pumping chamber  246  is separated from the outlet duct  256 . 
     Starting from this initial position, the first piston  250  is manually forced downward by means of the actuating device  230 . The diaphragm  234  is hereupon elastically deformed, at the same time as the hermetic sealing of the pumping chamber  246  is maintained. After the first piston  250  has been moved past an inlet duct  244 , the pumping chamber  246  is outwardly sealed. In the course of the further movement, the air in the pumping chamber  246  is compressed to the point where the air pressure is sufficiently high to force the opposed piston  260  counter to the spring force of the opposed piston spring  264  in the direction of its lower limit position. As soon as the opposed piston  260 , as is represented in  FIG. 3   b , makes its way into the region of the outlet duct  256 , the compressed air escapes from pumping chamber  246 . As soon, also, as the first piston  250  has reached the rim of the outlet duct  256 , the pumping chamber is completely empty. Forced upward by the force of the opposed piston spring  264 , the opposed piston  260  is pressed flush against the first piston  250 , so that the volume of the pumping chamber  246  is approximately zero in this state. 
     During the return stroke of the piston  250 , the opposed piston  260  remains pressed flush against the piston  250  until such time as the opposed piston  260  has reached its upper limit position, which is defined by the limit of the opposed piston guide  262 . From this position, which is represented in  FIG. 3   c , the pumping chamber volume  246  re-enlarges in the course of the continued return stroke of the first piston  250 , whereupon a strong underpressure is created in the pumping chamber  246 . As soon as the first piston  250  has arrived back in the region of the inlet duct  244 , medium is therefore abruptly sucked out of a medium container (not represented) through the inlet duct  244  into the pumping chamber  246 . 
     This state with filled pumping chamber  246  is represented in  FIG. 3   d . Starting from this state, the discharger can be used in a prescriptively correct manner. 
       FIG. 4   a  to  4   d  show a fourth embodiment of a discharger according to the invention. In this fourth embodiment, the transverse arrangement of a pump in the discharger corresponds to the first three embodiments. 
     The peculiarity of this fourth embodiment lies in a specially designed pumping device  340 . A pumping chamber  346  is delimited on an end face  340 A by a piston  350 . The side wall of the pumping chamber is formed by a bellows  347 . This bellows  347  is secured by its marginal region  354  in the housing on the side facing away from the piston, so that the pumping chamber  346  which is closed off by it remains free from impurities which infiltrate the housing in the region of the piston  350 . On the end face situated opposite the piston  350 , a medium inlet duct  344  and a medium outlet duct  356  open out into the pumping chamber  346 , an inlet valve  330  having a valve slide  332  being provided on the inlet duct  344 . The valve slide  332  is provided as a hollow cylinder which is closed on one side and on the open bottom side of which a circumferential latching edge  334  extends inward, which latching edge prevents the valve slide  332  from sliding off a cylindrical attachment  345  of the inlet duct  344 . Corresponding to the valve slide  332 , molded onto the piston  350  is an actuating pin  351 , which extends in a pumping direction  390  and is disposed above an outer edge of the closed side of the valve slide  332 . 
     The represented pumping device  340  allows a good ventilation of the pumping chamber  346  in the course of the activation of the discharger. The activation is explained below with reference to  FIG. 4   a  to  4   d.    
       FIG. 4   a  shows an initial position of the discharger. In this delivery state, the pumping chamber  346  has its maximum volume and is filled with air. Starting from this state, the piston  350 , which simultaneously constitutes an actuating device, is forced downward in the pumping direction  390 . This results in an increase in air pressure in the pumping chamber, with the result that the valve slide  332  slips downward on the attachment  345  of the inlet duct  344  and thus closes off the inlet duct  344 , as represented in  FIG. 4   b . In the course of the continued stroke movement of the piston  350 , the air in the pumping chamber  346  is further compressed until the actuating pin  351  reaches the valve slide  332 . As a result of the eccentric force which the actuating pin  351  exerts upon the valve slide, the latter—as is represented in  FIG. 4   c —is tilted, so that the inlet duct  344  is opened and the overpressurized air can escape from the pumping chamber  346 . As is represented in  FIG. 4   d , the medium then, during the return stroke, makes its way out of a medium container (not represented) through the inlet duct  344  into the pumping chamber, after the valve slide  332  has been removed from the inlet duct owing to the underpressure in the pumping chamber  346  in the course of the return stroke. The medium which has got into the pumping chamber can then, upon the subsequent actuation of the piston  350 , be discharged through the discharge opening  368  of the discharge valve unit  360 , the valve slide  332  ensuring, in this normal operation also, that the inlet duct  344  is closed for the pressure build-up in the pumping chamber  346 . Insofar as, in such a stroke movement in normal operation, in the lower limit position, the inlet duct  344  is opened by the actuating pin  351 , the remaining medium escapes from the pumping chamber  346  back into the medium container.