Abstract:
Manually operable pump for dispensing atomized liquids, the pump having passageways enabling air to enter the container on which the pump is mounted, when a vacuum forms in the container on dispensing liquid through the pump.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a manually operated invertible pump for dispensing atomized liquids withdrawn from a liquid container, on the mouth of which the pump is mounted usable both in the upright position, i.e. with the pump facing upwards from the container, and in the inverted position, i.e. with the pump facing downwards from the container. 
   BACKGROUND OF THE INVENTION 
   Many types of invertible pumps are known, such as those described in U.S. Pat. No. 5,222,636, U.S. Pat. No. 4,775,079, U.S. Pat. No. 4,277,001, U.S. Pat. No. 5,353,969, U.S. Pat. No. 5,738,252, EP-A-0648545 and EP-A-1029597. 
   All pumps, whether invertible or non-invertible (i.e. usable with the pump only in the upright position) must enable air to escape from the compression chamber of each pump on priming (i.e. when the air present in the pump compression chamber must be expelled to the outside, to enable a vacuum to form in the chamber, with consequent drawing of liquid into the pump), and to enable external air to enter the container on which the pump is mounted when a vacuum forms in the container following liquid dispensing by the pump. 
   The problem of external air entry into the container is particularly delicate in the case of invertible pumps, because such pumps must be able to be used and operated without liquid leakage or escape when the pump is in the inverted position, i.e. surrounded by and immersed in liquid which collects in proximity to the container mouth when the pump is mounted; this means that air must be able to enter the container through passageways from which, however, the liquid must not flow or drip out. 
   The most effective system is that described in U.S. Pat. No. 5,353,969 in which between the outer surface of the end of the pump hollow body and the opposing inner surface of the ring cap which fixes the pump to the container mouth there is provided a long, thin spiral groove, of which one end is open to the pump exterior and the other end opens below the pump, i.e. in communication with the interior of the container on which the pump is mounted: the dimensioning of the spiral groove is critical, being such as to prevent liquid outflow through it (with consequent dripping from the pump when used in the inverted position) but to allow passage of the air drawn from the outside into the container when a vacuum is formed therein following liquid dispensing by the pump. However, this system presents numerous drawbacks, such as the considerable difficulty of moulding the various components of the pump, the structure of which is very complex, the possible outward dripping of liquid through the grooves when the pump is in its inverted position and is retained in that position without the pump being operated, and the possible escape through the grooves of vapour originating from the liquid enclosed in the container when the pump is in its upright position. 
   SUMMARY OF THE INVENTION 
   The main object of the present invention is to provide an invertible pump with air passageways for the aforesaid purpose, in which the pump and its new components are of simple structure, very easy and economical to produce, and simple to assemble, and in which any dripping of liquid to the pump exterior is totally prevented even when maintained for lengthy periods in the inverted position, either with the pushbutton completely pressed down or left free in its rest position. 
   This and further objects are attained by a pump comprising a cup-shaped body housing a sealedly translatable piston to which one end of a hollow stem is connected, its other end projecting from the cup-shaped body and carrying a cap for manually operating the pump and for dispensing the atomized liquid, a ring cap for applying the cup-shaped body and with it the pump to the mouth of a container for the liquid to be dispensed and a seal gasket interposed between the ring cap, the cup-shaped body and the hollow stem, wherein the outer surface of the hollow stem is of reduced diameter at that portion thereof which lies opposite the gasket when the stem is in an intermediate position between its two end-of-travel positions, to leave free an air passageway between the stem and the gasket, there being provided between the gasket and the cup-shaped body and respectively between the cup-shaped body and said ring cap at least one narrow passageway which connects that portion of the cavity of the cup-shaped body situated between the pump piston and the gasket to the free space between the outer surface of the cup-shaped body and the ring cap. 
   Preferably, said passageway between the cup-shaped body and the ring cap is defined by at least one discontinuous rib which projects from the outer surface of the cup-shaped body to abut against the opposing surface of the ring cap. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The ensuing description illustrates a non-limiting embodiment of the pump, given with reference to the accompanying drawings, in which: 
       FIG. 1  is a longitudinal section through a pump shown in its rest position; 
       FIG. 2  is an enlarged section through that pump portion about its inner seal gasket, shown in that position in which the pump stem lies between its two end-of-travel positions; and 
       FIG. 3  is similar to  FIG. 2  but with the pump stem pushed totally down into its end-of-travel position to operate the pump. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The pump shown in  FIG. 1  has a structure totally similar to that illustrated in EP-A-1334774 and comprises a cup-shaped body  1  housing a piston  2  sealedly translatable within the cylindrical cavity of the body  1 , a hollow stem  3 , of which the lower end (with respect to  FIG. 1 ) is connected to the piston  2  and the upper end carries, projecting above the body  1 , a cap  4  for manually operating the pump and for dispensing the atomized liquid. 
   The pump body  1  can be screwed onto the mouth of a container (not shown) by a threaded ring cap  5 , also of known structure. 
   The lower end of the body  1  is bounded by a base wall  6  having a hole in which one end of a dip tube  7  is mounted to enable the liquid to rise from the container to a suction and compression chamber  8 , intercepted lowerly by a ball  9  housed and movable within a cage  10  below which a ball  11  is housed translatable within the cylindrical hole of an appendix  12  presenting longitudinal grooves (which prevent the ball  11  from forming a seal within the hole of the appendix  12 ). The ball  9  is translatably retained within the cage  10  by a series of tubular appendices  13  which project from the cage and have their free ends bent towards the pump axis: the balls  9  and  11  form, with the respective seal seats provided in the cage  10 , two unidirectional valves which enable communication between the chamber  8  and the cavity of the dip tube  7 , or which intercept and prevent this communication, when the pump is in the upright position (as shown in the drawings) or is in the inverted position respectively: in this latter case the liquid can penetrate into the cavity  8  through an aperture  14  provided in the body  1  (position in which the ball  11  rests and seals against its seat in the cage  10 ). 
   The pump structure described up to this point does not form part of the present invention, which instead relates to the structure of the upper part (with respect to  FIG. 1 ) of the pump, where it can be seen that the free end  15  of the body  1  is inserted into and retained in a seat defined by a tubular wall  16  of the ring cap  5  with an interposed seal gasket  17  which is in contact with the inner surface of the end  15  of the body  1  and seals against the outer surface of the portion  18  of the stem  3  when the stem  3  (and hence the pump) is in its rest position shown in  FIG. 1  (in which an annular rim  19  projecting from the stem is inserted into and seals within an annular seat provided on the adjacent surface of the gasket  18 ). As can be seen from the drawings, the outer surface of the stem  3  is not of constant diameter, but presents a portion  20  of smaller diameter than the portion  18 : this stem portion  20  is provided in such a position and has such dimensions that when the pump is operated and the stem is in an intermediate position ( FIG. 2 ) between its two end-of-travel positions, a passageway  22  through which air can penetrate from the outside to the inside of the pump chamber  8  is left free between the surface of said reduced portion  20  of the stem and the opposing surface of a lip  21  forming part of the gasket  17 . 
   From the drawings it can be seen that a continuous annular rib  23  projects from the reduced portion  20  of the stem  3 , to position itself and seal against the lip  21  of the gasket when the stem is pushed completely down ( FIG. 3 ) to its end-of-travel position within the pump body  1 . 
   From the drawings (in particular the left portion of the enlarged view of  FIG. 2 ) it can also be seen that the seal gasket  17  has a tubular annular appendix  24  which is inserted into the end  15  of the body  1 , but leaving free a narrow passageway  25  which prolongs into a passageway  26  provided between the gasket and the free end of said end  15  of the body  1 , this end  15  presenting on its outer surface an annular rib  27  which is discontinuous (i.e. interrupted along a short length): at the interruption in the annular rib  27 , between the outer surface of the end  15  and the opposing inner surface of the tubular wall  16  of the ring cap  5  (where the free end of the body  1  is inserted and securely retained) a narrow passageway  28  is formed opening below the rib  27  in a free annular space  29  which is in free communication with the outside of the pump body. 
   It will be assumed that the pump is in the rest state of  FIG. 1  in which the lip  21  of the gasket  17  seals against the portion  18  of the stem  3 , the seal being considerably increased by the forced insertion of the annular rim  19  of the stem into the annular seat provided on the lower face of the gasket. Under these conditions the interior of the pump body and the interior of the container on which the pump is sealedly mounted are completely isolated from the outside environment independently of whether the pump is in its upright or inverted position. 
   When the pump is operated, the stem  3  is lowered into the pump body and its reduced portion  20  becomes positioned in front of the gasket lip  21  ( FIG. 2 ), leaving free the passageway  22  through which air can pass (from the outside to the inside) to directly penetrate into the container through the passageways  22 ,  25 ,  26 ,  28 . This air passage from the outside to the inside of the container can take place only if the container is under vacuum, which occurs each time liquid is dispensed to the outside by the pump. 
   It will be noted that, even if the pump is used in the inverted position, the liquid in which the pump is immersed cannot escape through said small passageways both because the air drawn in by said vacuum flows through them (from the outside to the inside), and because these passageways are of very small cross-section and define a very tortuous path. With further lowering of the stem  3  within the body  1  (i.e. when the pump is pushed down to its end-of-travel position to dispense all the liquid collected within the pump cavity), the continuous annular rib  23  projecting from the stem becomes positioned against the lip  21  of the gasket  17  ( FIG. 3 ), so sealing against it and preventing escape or dripping of the liquid, even if the pump is used in the inverted position. 
   It can be added that the described pump structure is very simple, with all its components being very simple to produce and install, so that the cost of the finished pump fixed onto the ring cap  5  is also very low.