Abstract:
On order to simplify the design of a pump intended for use with flowable elements, especially a cosmetic pump provided with a base plate ( 1 ) which can be secured to a container ( 2 ) and presents, once mounted, a lower side ( 6 ) turned to the container and an upper side ( 7 ) turned in the opposite direction, with an inlet ( 14 ) for letting through the element stored in the container ( 2 ) and, around the inlet on the upper surface, a sleeve for receiving a pumping device with a cover-fitted piston ( 21 ), which is pushed by at least one compression spring against the base plate ( 1 ), while said piston cover has a lower side ( 21   a ) turned to the container ( 2 ), an upper side ( 21   b ) turned in the opposite direction and an outlet ( 23 ), while said lower side ( 21   a ) is provided with a sealing sleeve ( 22 ) mounted moveable in a substantially axial direction, it is suggested that the pumping device should be fitted with a valve spring ( 4 ) presenting a sealing bottom plate ( 20 ) laid on the inlet in the base plate and a sealing top plate ( 31 ) laid on a support emerging radially relative to the longitudinal axis ( 20, 50 ) of the pump, while both the bottom plate ( 30 ) and the top plate ( 31 ) are linked by at least one spring element.

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a pump intended for use with flowable media, especially a cosmetic pump, provided with a base plate which can be secured to a container and presents, once mounted, a lower side turned to the container and an upper side turned in the opposite direction, with an inlet for letting through the medium stored in the container and, around the inlet on the upper surface, a sleeve for receiving a pumping device with a cover-fitted piston, which is pushed against the base plate by at least one compression spring, while said piston has a lower side turned to the container, an upper side turned in the opposite direction and an outlet, while said lower side is provided with a sealing sleeve mounted moveable in a substantially axial direction. 
     A known pump of the type described is known to the applicant from prior art available within the company. The pump comprises a steel ball, which can be positioned on the inlet in the base plate to form a seal and which is pressed into or onto the inlet in the base plate by two helical springs which can be clamped below the lower side of the piston. As a rule, intermediate elements are inserted between the individual helical springs in this context, in order to improve the guidance of the springs. Packing rings are used to form a seal between the piston and a cap which can be mounted on it and serves to simplify operation of the piston. As a rule, a pump known from the prior art consists of 7 to 8 different components. As many of the components as possible are preferably made as injection-moulded plastic parts and fastened on a neck of the container. 
     Comparable pumps are known from DE 32 46 105 and DE 29 02 624. 
     These pumps have various drawbacks. On the one hand, their assembly is time-consuming and expensive, as several components, which are additionally made of different materials, have to be accurately connected to one another in order to guarantee perfect operation of the pump. A certain minimum overall height of the pump is necessary owing to the number of components. As a result of this relatively tall design, a major portion of the pump reaches up into the upper bottle neck. This is a disadvantage, particularly in view of the increasing use of transparent containers, as this part of the pump spoils the overall aesthetic impression. In addition, a sufficiently large opening is required in order to insert the pump into the container. On the other hand, these components cannot be transferred to the area above the bottle neck without further ado, as there are again certain restrictions regarding the overall height. 
     SUMMARY OF THE INVENTION 
     Consequently, the object of the present invention is to simplify the design of the generic pump. 
     According to the invention, this object is solved in that the pumping device has a valve spring which is provided with a sealing bottom plate which can be laid on the inlet in the base plate and a sealing top plate which can be laid on a support of the sealing sleeve emerging essentially radially relative to the longitudinal axis of the pump, where the bottom plate and the top plate are linked by at least one spring element. The bottom plate is expediently designed as a disk valve. 
     The design of the valve spring is particularly simple. It preferably consists of a single component which is inserted between the sealing sleeve and the base plate sleeve during assembly. 
     No attention need be paid to the accurate fit and seating of several components relative to one another. This reduces the manufacturing costs. Moreover, the valve spring offers the opportunity of substantially reducing the overall height. The entire pumping device can be located in the area above the base plate, meaning that no components have to project into the container neck. This makes it possible also to use containers having an opening with a very small cross-section, which were previously unsuitable for the use of a pump. 
     The compression spring is preferably located between the lower side of the piston and the upper side of the base plate, on the side of the sealing sleeve and the base plate sleeve facing away from the centre line of the pump. This prevents the compression spring from coming into contact with the sealing sleeve or the base plate sleeve when the pump is operated. 
     It is particularly advantageous for simple and low-cost manufacturing and assembly if the compression spring is integrally moulded on the piston. This reduces the absolutely necessary number of components to four, as the pump then only comprises the base plate, the piston, the valve spring and the cap, although the cap is not an absolutely necessary component. 
     Particularly good guidance of the sealing sleeve is achieved if the upper side of the base plate displays a guide sleeve, which is integrally moulded on the base plate at a distance from the base plate sleeve in the direction facing away from the centre line of the pump, and the sealing sleeve engages between the base plate sleeve and the guide sleeve. However, if the pump is to be of particularly simple design, it is also possible for the sealing sleeve to engage the inner side of the base plate sleeve to form a seal and for no guide sleeve to be provided. 
     In order to enhance the sealing effect, the base plate sleeve has a lip seal which lies against the inner side of the sealing sleeve to form a seal. This means that additional packing rings can also be dispensed with. 
     For the same reason, the outer side of the sealing sleeve also preferably displays a lip seal which can be laid against the inner side of the guide sleeve to form a seal. The lip seals are preferably located on the top edges of the sleeves, although they can also be arranged in different positions, depending on the application. 
     In the case of a pump designed as an air-aspirating system, at least one inlet aperture is provided for ambient air, this inlet aperture being designed as an air aperture located on the side of the base plate sleeve facing away from the inlet in the base plate, through which air can flow into the container. However, the pump according to the invention can also be designed as an airless system, in which case the air aperture is dispensed with. 
     The air aperture is preferably located between the base plate sleeve and the guide sleeve. The sealing sleeve then acts as a control valve to regulate the entry of air into the container. Air can flow into the container when the pump is depressed to such a point that the sealing edge of the sealing sleeve enters the air aperture and there is thus no longer a seal between the sealing sleeve and the guide sleeve. 
     For using the pump in connection with liquid media, where the pump has an integrally moulded duct on the piston for guiding the medium out of the pump through an outlet aperture, the duct is designed in such a way that the flow velocity of the medium is increased. The duct is preferably integrated in the piston cover and is provided with a least one ring-shaped segment which displays a reduced cross-section at at least one point. The ring-shaped segment acts as an acceleration chamber, in which the flow velocity of the medium is greatly increased as a result of the centrifugal force. 
     The duct can also display a linear segment, where the cross-section of the linear segment decreases in the direction of flow of the medium. This nozzle-type design likewise increases the flow velocity of the medium. The duct can display both an arc-shaped and a linear segment, which merge into each other in order to combine their effects. Depending on the field of application, it is also possible to provide an alternating arrangement of several different segments. 
     The duct can additionally display a deflector wall running essentially perpendicular to the direction of flow of the medium flowing through the duct. The medium is atomised when it hits this baffle wall. 
     In order to further reduce the overall height, it is possible, in the case of a pump operated by means of a cap fitted on the piston, to integrally mould at least part of the duct in the cap, so that the duct is formed between the cap and the piston. 
     The cap is preferably provided with an elastic sealing lip located on the outlet aperture to seal off the outlet aperture when the pump is not in use. In this way, the medium is protected against ambient influences and against drying out. It is particularly advantageous if this sealing lip is integrally moulded on the cap. When the pump is used, the elastic sealing lip is forced aside by the pressure of the medium, allowing the medium to escape. At the same time, the sealing lip causes atomisation of the medium in the case of liquid media. 
     In a version of the pump according to the invention which is designed as a lotion pump, the piston and the cap form an aperture, in the form of a slit-type nozzle for instance, as a result of the adjacent area at the outlet aperture. The slit-type nozzle thus formed in the area between piston and cap is considerably easier to manufacture than the slit-type nozzles known from the prior art, the manufacture of which requires compliance with very close tolerances and which are highly susceptible to wear as a result. In the slit-type nozzle according to the invention, two prefabricated parts, i.e. the cap and the piston, are simply assembled without having to pay attention to any special tolerances. 
     In order to further simplify manufacture, the bottom plate and the top plate are connected by two torsion springs which are integrally moulded to the bottom plate and the top plate. Alternatively, other types of spring, such as flat spiral springs, can also be used. 
     In the preferred configuration, the valve spring displays two torsion springs, which are offset relative to each other and integrally moulded on the top plate. This design ensures that the torsion springs do not interfere with each other when loaded and slide past each other when they bend. In terms of manufacturing, this design has the additional advantage that a split mould with two followers can be used, meaning that the valve spring can easily be removed from the mould after injection. 
     The top plate preferably has a smaller outside diameter than the inside diameter of the sealing sleeve in the area above the support. This design ensures that the medium can escape. Moreover, the top plate is arched towards the side facing away from the base plate, this guaranteeing the necessary pretension for proper functioning between the upper point of contact of the top plate on the lower side of the piston and the lower point of contact of the top plate on the support. 
     The base plate, piston, cap and valve spring are preferably made of one material. This also facilitates disposal. 
     An example of the device is illustrated in the drawing and explained in detail below based on the figures. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The figures show the following: 
     FIG. 1 A cross-sectional side view of a configuration of the pump according to the invention designed as a spray pump, in relieved condition, 
     FIG. 2 The pump according to FIG. 1 when operated, 
     FIG. 3 A section along Line III—III in FIG. 2, 
     FIG. 4 The pump according to FIG. 1 in its limit position, 
     FIG. 5 The pump according to FIG. 1 when relieved, 
     FIG. 6 A cross-sectional side view of an alternative configuration of the pump according to the invention, 
     FIG. 7 The pump according to FIG. 1 in a clad design, 
     FIG. 8 A front view of the pump according to the invention, 
     FIG. 9 A cross-sectional side view of an alternative configuration of the pump according to the invention, designed as a lotion pump, and 
     FIG. 10 A front view of the pump according to FIG.  9 . 
    
    
     The use of the terms “outwards” and “inwards” below relates to the longitudinal axis  20  of the pump. Outwards means in the direction facing away from longitudinal axis  20 , while inwards means facing towards longitudinal axis  20 . The terms “upwards” and “downwards” refer to the pump located on container  2 . Downwards means the direction towards container  2 , while upwards means the direction away from the container. 
     According to the drawing, the pump essentially comprises a base plate  1 , which is secured to a container  2 , a piston  3 , a valve spring  4  located between base plate  1  and the piston, and a cap  5 . 
     Base plate  1  consists of a cover-like segment which, when mounted, has a lower side  6  facing towards the container and an upper side  7  facing away from the container and which rests on the edge of a container sleeve  8  of container  2  to form a seal. In the region of the peripheral edge of lower side  6  of the base plate, the latter displays a container edge  9 , running perpendicular to base plate  1  in the direction of container  2 , and, on the upper side  7  of the base plate, a piston edge  10 , running perpendicular to base plate  1  in the opposite direction to container  2 . Container edge  9  and piston edge  10  are integrally moulded on base plate  1 . Base plate  1  is preferably made of an injection-moulded plastic material. 
     At its lower end, container edge  9  displays a collar  11 , running radially in the direction of container  2 , on its inner side facing towards container  2 . This collar  11  engages a recess  12  provided on the outer side of container sleeve  8 . Base plate  1  can thus be connected to container  2  in snap-in fashion. The inner side of the upper end of piston edge  10  likewise displays a collar  13 , which serves to fix piston  3  and cap  5  in place and to reduce the friction between these components when the pump is operated. 
     Above the centre of container sleeve  8 , base plate  1  displays an inlet  14 , through which the medium contained in container  2  can be transported from container  2  by means of the pump. In this context, the medium is sucked in from container  2  via a riser  15 . Riser  15  is inserted in a riser sleeve  16 , integrally moulded on the lower side  6  of the base plate around inlet  14  in the base plate, and is connected to the base plate to form a seal. 
     A cylindrical base plate sleeve  17  is integrally moulded on the upper side  7  of the base plate. This base plate sleeve  17  surrounds the inlet  14  in the base plate in the form of a circular ring. Moreover, also integrally moulded on the upper side  7  of the base plate is a guide sleeve  18 , which is located at a distance from base plate sleeve  17  in the direction facing away from the longitudinal axis  20  of the pump in such a way that a circular annular gap  19  is formed between the outer surface of base plate sleeve  17  and the inner surface of the guide sleeve. This annular gap  19  serves to accommodate a sealing sleeve  22 , described below. 
     Piston  3  displays a piston cover  21 , which runs essentially transverse to the longitudinal axis  20  of the pump and has a lower side  21   a  of the piston, facing towards container  2 , and an upper side  21   b  of the piston, facing away from the container. A cylindrical sealing sleeve  22  is integrally moulded on the lower side  21   a  of the piston. This sealing sleeve  22  surrounds a piston outlet  23  provided in the piston cover  21  in annular fashion. In the present case, piston outlet  23  is offset in relation to longitudinal axis  20  of the pump, but can be located at any point on piston cover  21  within sealing sleeve  22 , depending on the field of application. 
     The diameter of sealing sleeve  22  is slightly larger than that of base plate sleeve  17  but, on the other hand, slightly smaller than that of guide sleeve  18 . In this way, it is ensured that, when the pump is assembled, sealing sleeve  22  is connected to base plate sleeve  17  in sealing fashion in that it engages annular gap  19 . Sealing sleeve  22  is guided by guide sleeve  18  on its outer side and by base plate sleeve  17  on its inner side. In order to improve the seal, both base plate sleeve  17  and the sealing sleeve are provided with lip seals  24 ,  25 , running radially away from longitudinal axis  20  of the pump. Lip seal  24  of base plate sleeve  17  forms a seal against the inner surface of sealing sleeve  22  under pre-tension, while lip seal  25  of sealing sleeve  22  forms a seal against the inner side of guide sleeve  18  under pre-tension. The space enclosed by base plate sleeve  17  and sealing sleeve  22  forms a pump chamber  35 . 
     Lower side  21   a  of the piston displays an integrally moulded spiral compression spring  26 , which is located at a distance from sealing sleeve  22  in the radial direction away from the longitudinal axis  20  of the pump in such a way that it lies on the upper side  7  of the base plate at a distance from guide sleeve  18  in the radial direction away from the longitudinal axis  20  of the pump. The present compression spring  26  is of double design in order to obtain a higher spring power with a compression spring  26  of short length. The spring can also be of single design if a greater overall height of the pump is acceptable. 
     Moreover, a cladding element  27 , running downwards, is integrally moulded on the outer edge of lower side  21   a  of the piston. This cladding element  27  serves to provide axial guidance of piston  3  during operation and assembly of the pump with the cap and clads the pump. The lower end of cladding element  27  lies against collar  13 . 
     Piston  3  is operated via a cap  5 , which is fitted on piston  3  and surrounds it in the manner of a cover. For fixing in place, cap  5  is connected by a snap fit to collar  13  via a bead  29 , which is integrally moulded on cap  5  and runs radially outwards. This snap-fit connection prevents unintentional detachment of the pump from container  2 . Cap  5  is provided with a recess designed to accommodate cladding element  27 . 
     Valve spring  4  displays a sealing bottom plate  30  which lies on the inlet  14  in the base plate, a sealing top plate  31  which lies on a support emerging radially relative to the longitudinal axis  20  of the pump, and two torsion springs  32 ,  33 , integrally moulded between bottom plate  30  and the top plate. The support is designed as an annular collar  34 , integrally moulded on the upper end of the inner side of sealing sleeve  22 . 
     The outside diameter or the dimensions of bottom plate  30  is or are slightly smaller than the inside diameter of base plate sleeve  17 , meaning that bottom plate  30  is capable of slight movement relative to base plate sleeve  17 , but is also guided by base plate sleeve  17  at the same time. In order to increase the sealing effect between bottom plate  30  and base plate  1 , the upper side of the base plate displays a sealing film  59 , which is located around the inlet  14  in the base plate and is integrally moulded on the base plate. 
     Top plate  31  is arched upwards. The zenith of the arch of top plate  31  is in contact with lower side  21   a  of the piston. The arch clamps top plate  31  between lower side  21   a  of the piston and the support. In this way, top plate  31  forms a seal with the support. As a result, an air-tight pump chamber  35  is formed in the space between bottom plate  30 , top plate  31 , base plate sleeve  17  and sealing sleeve  22 . 
     The outside diameter of top plate  31  is smaller than the inside diameter of sealing sleeve  22  in the region above the support. This ensures that the edge of top plate  31  can be lifted off the support when pressure develops inside pump chamber  35 . 
     FIG. 1 illustrates the pump in its starting position, in which compression spring  26  is relaxed. The individual steps of pump operation are illustrated in FIGS. 2 to  5 . The pump chamber is already filled with medium at the start of the sequence described below. The direction of flow of the medium is indicated by arrows. 
     In FIG. 2, an external force is applied to cap  5 . The piston is pressed downwards against the force of compression spring  26  and torsion springs  32 ,  33 . At this time during the relative motion of piston  3  in relation to base plate  1 , lip seal  24  for the medium lies in sealing fashion against the inner wall of sealing sleeve  22 , and lip seal  25  lies in sealing fashion against the inner wall of guide sleeve  18 . The pressure inside pump chamber  35  lifts top plate  31  upwards and off collar  34 . The medium can now escape from pump chamber  35  and is transported from pump chamber  35  to piston outlet  23  through an annular gap forming between top plate  31  and collar  34 . At the same time, torsion springs  32 ,  33  and the pressure in the pump chamber press bottom plate  30  onto sealing film  59 , so that the medium cannot flow back into container  2 . 
     As can be seen from FIG. 3, in particular, when the medium leaves piston outlet  23 , it flows into duct  36 , which is integrally moulded in upper side  21   b  of the piston and is designed in such a way as to increase the flow velocity of the medium. To this end, duct  36  is initially designed as an essentially semi-circular curved path, the narrowest radius of which is located at point  37 . The medium is accelerated by centrifugal force as a result of this design of duct  36 . 
     In the area downstream of point  37  with the narrowest radius, duct  36  displays a deflector wall  38 , which runs essentially perpendicular to the direction of flow of the medium flowing through the duct. In the case of liquid media, this deflector wall  38  causes droplet formation, as the cohesion of the substance is partially overcome as a result of the impact of the medium on the deflector wall. The direction of flow of the medium is redirected downwards by deflector wall  38 . 
     The medium now enters a linear segment  39  formed within the upper side  21   b  of the piston. To be precise, this linear segment  39  is formed partly in the upper side  21   b  of the piston and partly in the lower side of cap  5 , which together form linear segment  39  when assembled. The cross-section of linear segment  39  decreases towards outlet aperture  40 , having its smallest cross-section at outlet aperture  40 . This design of the duct once again increases the flow velocity of the medium. 
     Outlet aperture  40  is sealed off by sealing lip  41 , which projects downwards and is integrally moulded on the lower side of cap  5 . The pressure of the medium generated when operating the pump forces this elastically designed sealing lip to the side, allowing the medium to escape. In addition, sealing lip  41  once again provides for the atomisation of liquid media. 
     FIG. 4 shows the pump in its limit position, i.e. the pump is pressed all the way down. In this position, no more medium flows out of outlet aperture  40 . Bottom plate  30  again lies against inlet  14  in the base plate to form a seal, and top plate  31  lies against collar  34  to form a seal. Lip seal  25  of the sealing sleeve protrudes into air aperture  28 , meaning that there is no longer a sealing fit between lip seal  25  and the inner side of guide sleeve  18 . At this stage, ambient air flows into the pump between collar  13  of piston edge  10  and cladding element  27 , flowing from there through the gap between the lower side of cladding element  27  and upper side  6  of the base plate, through compression spring  26 , between cladding element  27  and sealing sleeve  22  into air aperture  28  and thus into container  2 , this resulting in equalisation of the pressure in the container. The path of the air is indicated by arrow A in FIG.  4 . 
     FIG. 5 shows the pump during relief of the pressure. Compression spring  26  forces piston  3  and cap  5  back into their starting position. Lip seal  25  again lies against the inner side of guide sleeve  18  to form a seal, having moved out of the area of air aperture  28 . A vacuum develops in pump chamber  35  during the upward relative motion of piston  3  in relation to base plate  1 . This vacuum lifts bottom plate  30 , with the result that medium is sucked from container  2 , through riser  15  and into pump chamber  35 . In this way, pump chamber  35  is filled and is again ready for operation for a further pump cycle. If pump chamber  35  contains no medium when used for the first time, it is first filled by operating the pump several times. 
     FIG. 6 shows an alternative configuration of the pump. The design of the pump essentially corresponds to that of the pump illustrated in FIGS. 1 to  5 . In contrast to the latter, the configuration illustrated here is designed as a screw-type version. On the inner side of container edge  9 , the pump displays an integrally moulded female thread  42 , which engages an integrally moulded male thread  44  on the outer side of container sleeve  8 , which corresponds to female thread  42 . In addition, this configuration displays an elastic packing ring  45 , located between the container edge and lower side  6  of the base plate, which maintains the necessary pre-tension in order to prevent unintentional detachment of the pump from container  2 . 
     FIG. 7 illustrates another configuration of the pump according to the invention. This essentially corresponds to the clamp-type version illustrated in FIGS. 1 to  5 . In contrast to the latter, the pump is additionally provided with a cover cap  46 . This cover cap covers cap  5  and is preferably made of aluminium, which is particularly resistant to numerous media, such as perfume, hairspray and the like. Moreover, it is inexpensive to manufacture. In the area of outlet aperture  40 , cover cap  46  is provided with a hole  47 , through which the medium can escape unhindered. In order to be certain not to obstruct the flow of medium, hole  47  is preferably substantially larger than outlet aperture  40 . Moreover, the pump can be provided with a ring  48 , located on the outer sides of container edge  9  and piston edge  10  of base plate  1 , which is preferably made of the same material as cover cap  46  and likewise serves to protect the pump against aggressive media, as well as to improve the styling. 
     FIG. 8 shows a front view of outlet aperture  40  of the pump from FIG.  7 . 
     The pump illustrated in FIGS. 9 and 10 represents an alternative configuration of the pump, designed as a lotion pump. A lotion is a viscous medium which does not need to be transported from the pump under such high pressure and which thus also does not need to be accelerated. In addition, atomisation is not required. The pump can, of course, also be used for other viscous media. 
     The essential difference in comparison with the configurations illustrated in the preceding figures, which can also be referred to as spray pumps, lies in the design of the duct between the cap and the piston, as well as the different design of the outlet aperture. 
     Piston  49  is provided with a piston outlet  51 , located at a position offset relative to the longitudinal axis  50  of the pump. This piston outlet  51  is located in the area of piston cover  52 , which is positioned within sealing sleeve  53 , integrally moulded on the lower side of piston  49 . 
     During pumping, the lotion passes from pump chamber  54  into duct  56 , formed between the lower side of cap  55  and the upper side of piston  49 . This duct takes the lotion direct ly to the outlet aperture, designed in the form of a slit-type nozzle, without passing via an acceleration chamber. 
     In the region of the outlet aperture, the adjacent areas of cap  55  and piston  49  are designed in such a way that a fine slit-type nozzle is formed between them. Duct  56  leads to slit  57  of the slit-type nozzle in essentially conical form. The slit-type nozzle is sealed off when the pump is not in operation, so that no bacteria can enter and the lotion is protected against drying out. When the pump is operated, slit  57  is easily opened by the internal pressure of the lotion, allowing the latter to escape. 
     The slit-type nozzle design according to the invention is far more favourable than that known from the prior art, where very close manufacturing tolerances have to be observed in the transition area from the cap to the slit-type nozzle integrally moulded on it, this making production highly complicated and expensive. For example, a steel core with a diameter of 0.75 mm is required for injection moulding of the plastic parts. In the invention, on the other hand, the slit-type nozzle is formed by assembling two prefabricated parts. 
     This is far more simple and requires no special manufacturing tolerances. 
     In order to prevent the lotion entering areas not intended for this purpose between cap  55  and piston  49  during pumping, a sealing film  58  is integrally moulded around duct  56  and piston outlet  51  on the lower side of cap  55 , which makes contact with the upper side of piston  49 . Sealing films of this kind can also be provided in the configuration illustrated in FIG.  1 . 
     As also clearly indicated by FIG. 9, riser  15  can also be slipped onto riser sleeve  16  from the outside. 
     FIG. 10 shows a front view of the pump from FIG. 9, looking towards the slit-type nozzle. 
     All the pump configurations illustrated in the figures are essentially rotationally symmetrical, cylindrical configurations, which are rotationally symmetrical about longitudinal axis  20  of the pump. However, it is also within the scope of the invention to design certain components in a position offset from the centre line  20  of the pump, i.e. to design the pump and container  2  in non-rotationally symmetrical form and to make provision for other geometries. 
     The individual components are preferably injection-moulded from a plastic material, meaning that their production is particularly simple and inexpensive. Some of the components can also be made of metal or other suitable materials, provided that they do not require the elasticity of a plastic. 
     The pump configuration according to the invention greatly simplifies the design of the pump. Compared to the prior art, only three or four parts are required instead of the previous eight parts and more. The design according to the invention reduces the overall height, so that the pump can be located entirely in the area above the base plate. This permits its use on containers whose aperture cross-section is small and limited. Really, all that is now required is a aperture cross-section of the container that is sufficient to insert the riser. As all the pump components can be injection-moulded from a plastic material, their manufacture is particularly simple and inexpensive. In addition, disposal is also facilitated. The pump can be operated with and without the cap. The design of the duct as an acceleration chamber in accordance with the invention makes it possible to dispense with additional nozzles for accelerating and atomising liquid media. These nozzles represent expensive individual parts in the prior art. In the non-air-aspirating configuration of the pump according to the invention, the container is expediently made of an elastic material.