Patent Publication Number: US-6910606-B2

Title: Piston operated fluid dispensing device capable of incrementally adjusting the volume being dispensed

Description:
The applicants claim priority from their previously file copending provisional application filed Oct. 26, 2002 and assigned Ser. No. 60/421,550. The present application relates to devices for dispensing a predetermined volume of liquid, as for example, for medication, and in particular to an adjustable device in which one can incrementally increase the volume of liquid being dispensed by rotating the stem to discharge positions corresponding to such incremental changes. 

   BACKGROUND OF THE INVENTION 
   Certain liquids, for example liquid medication, are needed in small predetermined volumes, and therefore it is desirable to have a dispensing device for dispensing predetermined volumes of liquid. In my U.S. Pat. No. 4,892,232 I disclosed such a device. 
   The amount of a certain medication needed by a first patient may, however, be different from the amount of the same medication needed by a second patient. For example, the amount of Tylenol that should be administered to a child depends upon the child&#39;s weight, with a ratio of 10 milligrams per 2.2 pounds of weight (one kilogram). A forty-four pound child should therefore receive a dosage of 200 milligrams and a fifty-five pound child should receive 250 milligrams. As a child grows, the dosage of this medication that he or she should receive, therefore, grows proportionate to his or her weight change. It is desirable, therefore, to provide a dispensing valve for which the volume of liquid being dispensed can be incrementally increased or decreased across a range of volumes to accommodate such needs. 
   An adjustable dose dispenser having a plurality of different sized metering chambers with a stem rotatable to select the chamber to be discharged was disclosed in my U.S. Pat. No. 5,085,351. In that device, each of the metering chambers had a flexible wall. Since this device required a separate metering chamber for each volume to be dispensed, the number of selected volumes available for one valve was limited to three or four. 
   As an alternative to selecting one of a plurality of chambers for varying the volume of fluid to be dispensed, a device can have a single chamber where the volume dispense from the chamber is adjustable. This can be accomplished by providing a piston for dispensing the liquid from the chamber where the length of the piston stroke is adjustable, as disclosed in my previously issued U.S. Pat. No. 5,813,187. The piston operated dispensing device of U can dispense a wide range of volumes of liquid, but the device as described in my above mentioned patent has certain problems. 
   One problem is that the volume of liquid being dispensed is adjusted by rotating the stem of the dispensing valve and the valve stem is connected a threaded stop member which rotates with the stem to vary the stroke of the piston. To operate properly, however, the piston is sealed against the cylindrical wall of the metering chamber and the seal around the perimeter of the piston creates resistance, inhibiting the manual rotation of the dispensing stem. 
   Another problem relates to the structure of a piston moveable within a cylindrical wall. To prevent the twisting of the piston within the wall of the valve housing, the threads or the steps that limit the stroke of the piston should provide should provide at least two limiting stop members, with the stop members spaced evenly around the circumference of the housing. Where two such stop members are positioned in diametrically opposed positions in the housing, only 180 degrees of rotation of the stem is available to vary the length of the stroke of the piston. As a result, the variability of the adjusting quality of the valves is diminished. 
   Another problem is that the device includes a spring for urging the piston in a direction that maximizes the volume of the metering chamber and the other end of the spring is fitted against a surface of the housing of the valve such that on rotation of the stem either the piston rotates with respect to the spring or the spring rotates with respect to the housing. In either case the movement of the plastic of the housing or of the piston against the spring causes particles of plastic to sheer off and enter the liquid being dispensed. The continuing use of the dispenser causes those particles to obstruct the small passages that extend through the stem of the dispenser and thereby inhibit its operation. 
   There is therefore, a need for an improved piston operated dispensing apparatus in which the volume. of liquid being dispensed may be more easily adjusted and which will not cause small particles of plastic to be released into the liquid. 
   SUMMARY OF THE INVENTION 
   Briefly, the present invention is embodied in a dispensing valve for use in a dispensing device consisting of a container filled with a pressurized liquid. In the preferred embodiment, portions of the valve extend above the upper surface of the container. The valve includes a stem the upper end of which is rotatable about its longitudinal axis and is axially moveable with respect to the enclosure and the body of the valve. The direction of the discharge nozzle is rotatable to any one of a predetermined number of discharge positions and the stem may be depressed to discharge a quantity of liquid or gel only when the discharge nozzle is at one of the predetermined discharge positions. The dosage of liquid to be dispensed for each of the discharge positions is printed on the upper portion of the valve near the associated position. 
   The valve has a generally tubular housing having an open lower end into which a piston is axially moveable. Within the housing is a cavity the outer walls of which are formed by the housing and the lower wall is defined by the upper surface of the piston such that the cavity is constricted as the piston moves upward within the housing. 
   The stem which extends axially through the upper end of the housing has an axial passage with a discharge opening at the upper end thereof and a second port extending through a wall in the stem. The stem is axially moveable between an extended position wherein the port in the wall of the stem is sealed against portions of the tubular housing, and a depressed position in which the port in the wall of the stem is in communication with the cavity such that liquid therein can be released to the ambient. A spring urges the stem to the extended position. 
   The valve further includes a float within the cavity which is locked for rotation with the stem, but is axially moveable within the cavity independent of the stem. The float provides means for limiting the movement of the piston within the cavity. In the preferred embodiment, the float has two poles angularly spaced from each other but not necessarily at diametrically opposite positions from each other, such that when the piston moves upward through the cavity, the poles of the float engage a surface on the housing at the upper end of the cavity. 
   Surrounding the aperture for receiving the stem in the upper end of the cavity, the housing has a plurality of invaginations arranged in pairs with the depth of each of the pairs being different from the depth of any other pair and the members of each pair of invaginations angularly spaced about the axis of the valve for receiving the poles of the float. Rotation of the stem of the valve to one of the preselected activation positions causes a corresponding rotation of the float within the cavity and the rotation of the poles to engage the invaginations corresponding to the markings on the exterior of the housing near the selected activation position. 
   Where the valve has an even number of discrete discharge selections, with each selection corresponding to a different volume of liquid being discharged through the valve, the poles on the float cannot be diametrically opposed to each other. If the poles were diametrically opposed to each other, the two members of each of the pairs of invaginations in the housing would also have to be diametrically opposed to each other and the valve would discharge exactly the same amount of liquid for any two diametrically opposed angular settings of the discharge valve. The consequence of such a configuration would be that the valve could be adjusted only through 180 degrees, rather than through 360 degrees, thereby limiting the number of volume selections to which the stem can be rotated. 
   Where the valve is configured to be adjustable to an odd number of settings, the invaginations in the upper surface of the housing may be positioned diametrically opposed to each, however, a means for keying the angular orientation of the float with respect to the stem must be provided, and we have found that the keying can be simplified by providing a pair of longitudinal ribs on the float which engage complementary pairs of longitudinal slots in the stem with the ribs on the float oriented adjacent to the poles. To insure that the parts can be assembled in only one orientation, it is preferable that the poles therefore not be diametrically apart from one another. It should be appreciated, however, that the measuring systems currently in use divide the units of volume into eighths or tenths, and therefore, it is desirable to provide a dispensing device in which the volume of liquid being dispensed is in units of one-eight or one-tenth of the maximum dispensable volume. Eighths or tenths are both even numbered numbering systems. 
   One feature of the present invention is that the refill port for admitting liquid into the cavity extends through a wall in the housing, rather than through a hole in the piston as was the case with prior art piston operated valves. Prior art valves having refill ports that extend through the piston relied upon a seal between the outer circumference of the piston and the inner wall of the housing to prevent leakage of liquid from the surrounding container into the cavity during discharge. Such leakage alters the accuracy of the dosage being dispensed and in the case of a sever leakage, holding the stem in the depressed condition for a lengthy period of time can result in the discharge of the entire contents of the container. 
   The valve of the present invention includes a diaphragm extending across the lower open end of the tubular housing that seals against the lower surface of the piston to provide a leakproof seal so as to prevent liquid from seeping around the outer edges of the piston and into the cavity. 
   Yet another advantage of the present invention is that the piston is urged downward within the housing by a coil spring which extends around the circumference of the float so as not to cause resistance to the rotation of the float. As a result, an operator may easily rotate the stem and float to a chosen selected volume without causing damage to the parts or incurring undue resistance. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention will be had after reading of the following detailed description taken in conjunction with the drawings wherein: 
       FIG. 1  is a fragmentary cross sectional view of a piston operated dispensing device in accordance with the prior art; 
       FIG. 2  is a side elevational view of a dispensing container having a dispensing valve according to the present invention; 
       FIG. 3  is a cross-sectional view of the container and valve shown in  FIG. 2  taken through line  3 — 3 ; 
       FIG. 4  is an enlarged cross-sectional view of the valve shown in  FIG. 3  prior to attachment to a container, with the actuator in the elevated position; 
       FIG. 5  is a further enlarger cross-sectional view of the valve shown in  FIG. 2  prior to attachment to a container, with the actuator in the depressed position; 
       FIG. 6  is an isometric view of the housing of the valve shown in  FIG. 4 ; 
       FIG. 6A  is a side elevational view of the housing shown in  FIG. 6 ; 
       FIG. 6B  is a cross-sectional view of the housing shown in  FIG. 6  taken through line  6 B— 6 B of  FIG. 6A ; 
       FIG. 6C  is a broken isometric view of the housing shown in  FIG. 6  exposing several of the invaginations therein;  FIG. 6D  is another isometric view of the housing of the valve shown in  FIG. 4 ; 
       FIG. 6E  is a cross-sectional view of the housing shown in  FIG. 6  taken through line  6 E— 6 E of  FIG. 6A  with the configuration of the pairs of invaginations marked therein; 
       FIG. 6F  is a greatly enlarged bottom elevational view showing the arrangement of the invaginations for receiving the poles of the float; 
       FIG. 7  is an isometric view of the stem for the valve shown in  FIG. 4 ; 
       FIG. 7A  is a side elevational view of the stem shown in  FIG. 7 ; 
       FIG. 7B  is a cross section al view of the stem shown in  FIG. 7  taken through line  7 B— 7 B of  FIG. 7A ; 
       FIG. 7C  is a top view of the stem shown in  FIG. 7 ; 
       FIG. 7D  is a cross-sectional view of the stem shown in  FIG. 7  taken through line  7 D— 7 D of  FIG. 7A ; 
       FIG. 7E  is a cross-sectional view of the stem shown in  FIG. 7  taken through line  7 E— 7 E of  FIG. 7A ; 
       FIG. 8  is an isometric view of a float for the valve shown in  FIG. 4 ; 
       FIG. 8A  is a side elevational view of the float shown in  FIG. 8 ; 
       FIG. 8B  is a cross-sectional view of the float shown in  FIG. 8  taken through line  8 B— 8 B of FIG.  FIG. 8A ; 
       FIG. 8C  is a top view of the float shown in  FIG. 8 ; 
       FIG. 8D  is a cross-sectional view of the float shown in  FIG. 8  taken through line  8 D— 8 D of  FIG. 8A ; 
       FIG. 9  is an isometric view of an actuator cap for the valve shown in  FIG. 4 ; 
       FIG. 9A  is a front elevational view of the actuator cap shown in  FIG. 9 ; 
       FIG. 9B  is a cross-sectional view of the actuator cap shown in  FIG. 9  taken through line  9 B— 9 B of  FIG. 9A ; 
       FIG. 10  is an isometric view of a seal for the upper portion of the housing of the valve shown in  FIG. 4 ; 
       FIG. 10A  is a cross-sectional view of the seal shown in  FIG. 10 ; 
       FIG. 11  is an isometric view of a refill port seal for the valve shown in  FIG. 4 ; 
       FIG. 11A  is a side elevational view of the refill port seal shown in  FIG. 11 ; 
       FIG. 11B  is a cross-sectional view of the refill port seal shown in  FIG. 11  taken through line  11 B— 11 B of  FIG. 11A ; 
       FIG. 12  is an isometric view of a piston for the valve shown in  FIG. 4  with a diaphragm secured to the lower surface thereof; 
       FIG. 12A  is another isometric view of the piston and diaphragm shown in  FIG. 12  with the parts exploded from one another; 
       FIG. 12B  is a cross-sectional view of the piston and diaphragm shown in  FIG. 12 ; 
       FIG. 13  is an isometric view of an enclosure for the valve shown in  FIG. 4 ; 
       FIG. 13A  is a side elevational view of the enclosure shown in  FIG. 13 ; and 
       FIG. 13B  is a cross-sectional view of the enclosure shown in  FIG. 13  taken through line  13 B— 13 B of FIG.  13 A. 
   

   DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , a piston operated adjustable dose dispenser  10  in accordance with the prior art includes a pressurized container  12  having a cap  14  with a crimp  15  around the outer circumference of the cap  14  to retain the cap  14  to the retainer  12 . A discharge stem  16  extends from a rim  17  at the upper end of a valve assembly  18 , the lower end of which extends into the cavity of the container  12 . A second crimp joins the rim  17  at the upper end of the valve to the cap  14  of the container  12 . The valve assembly  18  includes a cylindrical housing  20 , the stem  16 , a piston  26 , and a sleeve  22 , the lower surface  24  of which has either a spiraled configuration or a plurality of steps with each step defining a different longitudinal position along the length of the housing  20 . The piston  26  is positioned at the lower end of the housing and has an inner surface which, along with the inner surface  28  of the housing  20 , defines a variable volume cavity  30 , with the volume of the cavity  30  varying with axial movement of the piston  26 . 
   The piston  26  has a noncircular central opening  31  that fits around a complementarily shaped noncircular portion of the stem  16  such that the piston  26  is axially moveable with respect to both the housing  20  and the stem  16 , but will rotate within the housing  20  upon rotation of the stem  16 . Around the circumference of the upper surface of the piston  26  is one or more projections  32 ,  33  which extend axially along the inner surface  28  of the housing  20  and engage portions of the lower surface  24  of the sleeve  22 . By rotating the piston  26  the positioning of the projections  32 ,  33  is changed with respect to the lower surface  24  of the sleeve  22 , thereby varying the length of the stroke of the piston  26 . 
   A first coil spring  34  urges the stem  16  outward of the container  12  and a second coil spring  35  urges the piston  26  away from the lower end  24  the sleeve  22  and towards a stop  36  at the lower end of the cylindrical housing  20 . Rotation of the stem  16 , therefore, causes rotation of the piston  26  and thereby adjusts the length of the stroke of the piston  26  within the cavity  30 . 
   The discharge stem  16  has a first axial passage  38  extending from the upper end thereof to a port  40  in the side wall thereof which, when the stem  16  is depressed, provides communication between the interior of the cavity  30  and the ambient. The stem  16  also has a second axial passage  42  extending through the lower end thereof and opening through a second port  44  for providing communication between the cavity  30  and the interior of the pressurized container  12  when the stem is not depressed. 
   When the stem  16  is not depressed, as shown in  FIG. 1 , the cavity  30  is in communication with the pressurized liquid and the container  12  through the second passage  42  and the spring  34  urges the piston  24  towards the lower stop  36  to fill the cavity  30  with liquid. When the stem  16  is subsequently depressed the port  44  is closed and the port  40  is opened to ambient pressure. The pressurized liquid in the container  12  thereafter causes movement of the piston  26  forcing liquid through the first passage  38  and expelling it through the upper end of the stem  16  until the piston  26  reaches the lower end  24  of the sleeve  22 . 
   A problem with this embodiment can occur if the pressurized liquid in the container leaks around the sides of the piston  26  and enters the cavity  30 . This is likely to occur if the piston twists or becomes cocked within the tubular inner surface  28  of the housing  20 . To prevent the twisting of the piston  28  within the housing  20 , the lower surface  24  of the sleeve  22  is configured into two spirals or sets of steps, with each of the spirals or set of steps extending around only 180 degrees of the circumference of the housing. The piston  26  also has two upwardly extending parallel projections  32  that are 180 degrees apart such that one projection  32  engages one of the spirals or set of steps on the surface  24  and the second projection  24  engages the second spiral or set of steps on the surface  24 . As a result, the volume of the liquid being dispensed by the valve assembly  18  is varied during the rotation of the stem  16  through only 180 degrees because the second 180 degrees of rotation is identical to the first 180 degrees. 
   In the embodiment depicted rotation of the stem  16  causes rotation of the piston  26 . The second coil spring  35  extends between the nonrotatable second sleeve  22  and the rotatable piston  26  causing the metal parts of the spring  35  to scrape loose particles from either the sleeve  22  or the piston  26 . Also, the piston  26  is sealed around its perimeter to prevent leakage and the seals cause resistance to rotation of the stem  16 . The operator is therefore required to exert substantial force to rotate the stem, and the stem  16  must be adequately engineered to endure the torque applied thereto. 
   Referring to  FIGS. 2 and 3 , a dispenser  50  according to the present invention includes a pressurized cylindrical container  52  at the upper end of which is an actuator cap  53  having an elongate radially extending discharge nozzle  54 . Surrounding the base of the actuator cap  53  and extending above the upper surface of the container  52  is an upper portion  55  of a valve  56  in accordance with the present invention. The upper portion  55  of the valve  56  has a plurality of notches  57  around the circumference and printed near each notch  57  is a marking  58  indicative of the dosage of liquid to be dispenses upon the depression of the actuator with the nozzle  54  received into the associated notch  57 . The valve  56  is configured to administer a graduated range of dosages with the minimum dosage occurring when the nozzle  54  is received in the notch  57  having number 1 as the adjacent marking  58 . Each successive notch bears a successively larger marking  58  indicative of an incrementally larger dosage of the liquid administered by the valve. The open upper portion  55  is depicted as having eight notches  57  such that the actuator cap  53  can be rotated to any of the eight positions and will dispense a different amount of liquid  59  when the nozzle  54  is received in each of the eight notches  57 . 
   The container  52  has an opening  59  at the upper end, and outward of the opening  59  is a shoulder  60  which extends to a cylindrical wall  61  at the lower end of which is a bottom  62 . Fitted within the opening  59  of the container  52  is a flexible bag  63  filled with a liquid  64  to be dispensed. A propellant  65 , which may be a compressible gas such as carbon dioxide or a volatile hydrocarbon liquid, surrounds the bag  63  and creates pressure within the interior of the container  52  for exhausting the liquid  64  through the valve assembly  56 . The parts, including the container  52 , the bag  63 , and the valve  56 , are held in assembled relationship by a ferrule  66  that is crimped around a radial flange  67  on the valve  56 , a bead around the opening  59  of the container  52 , the upper end of the bag  63 , and an O-ring  68  which, when the ferrule is crimped, forms a seal. 
   Referring to  FIGS. 3 through 6F , the valve  56  includes a generally tubular housing  69 , the upper portion  55  of which extends above the ferrule  66  and has the notches  57  at the upper end thereof and markings  58  printed near each notch  57 . Extending radially outward from below the upper portion  55  is the radial flange  67  to which the ferrule  66  attaches. The housing  69  also has a longitudinal axis  70 , an open lower end  72 , and between the flange  67  and the open lower end  72  is an upwardly facing annular shoulder  76  leaving a reduced diameter tubular central portion  78  extending between the flange  67  and the shoulder  76 . Piercing the tubular central portion  78  are a pair of opposing transverse refill ports  80 ,  82 . Below the upwardly facing shoulder  76  is a lower tubular portion  83  and extending around the lowermost end thereof adjacent the lower end  72  is a downwardly facing shoulder  84  forming a smaller diameter cylindrical lip  86 . 
   Referring to  FIGS. 4 ,  5 ,  6 B,  6 C,  10 , and  10 A, within the central opening of the housing  69  and near the upper portion  55  thereof is a generally cylindrical inner retainer  88  for retaining a tubular elastomeric seal  90  having a cylindrical inner wall  92 . Adjacent the open lower end  72  of the housing  69  is a cylindrical inner wall  94  and above the cylindrical inner wall  94  is a narrower central cylindrical inner wall  96  at the upper end of which is an inwardly directed flange  98  to which the tubular inner retainer  88  is mounted. 
   Referring to  FIGS. 6B ,  6 C,  6 E, and  6 F, the inner wall of the housing  69  immediately above the cylindrical inner wall  94  consists of a plurality of invaginations  100  arranged in pairs numbered from  100 ( 1 ) to  100 ( 8 ), with each of the pairs being of different depth than any other of the pairs of invaginations as is further described below. 
   Referring to  FIGS. 4 ,  5 , and  7  to  7 E, axially moveable within the housing  69  is a stem  102  having a narrow diameter, generally cylindrical upper portion  104  having a flat  106  near the uppermost end thereof. Below the upper portion  104  is a radially flange  108  and below the flange  108  is a large diameter tubular lower end  110 . The cylindrical upper portion  104  has an axial passage  112  extending therethrough, with the passage  112  having an upper opening  113  at the upper end of the upper portion  104  and a second opening  114  in the outer wall of the upper portion  104  a short distance above the radial flange  108 . Extending through the radial flange  108  are a plurality of holes  115 ,  116  which extend parallel to the longitudinal axis  118  of the stem  102  for allowing liquid to flow between the opposite faces of the radial flange  108  and in and out of the interior of the tubular lower portion  110 . 
   The flange  108  extends across the upper end of the tubular lower portion  110 ; the tubular lower portion  110  having a cylindrical outer wall  120 . Below the cylindrical outer wall  120  are a plurality of longitudinal indentations  122  leaving a plurality of parallel ridges  124  between the indentations  122  with the outer surface of the ridges  124  defined by the cylindrical outer wall  120 . Below the indentations  122  and ridges  124  is a downwardly facing annular shoulder  126  and below the downwardly facing annular shoulder  126  is a lower tubular portion  128  having a pair of longitudinal slots  130 ,  132  therein. As best shown in  FIGS. 7D and 7E , extending upward into the inner surface  133  of the stem adjacent the indentations  122  and the cylindrical surface  120 , are grooves  135 ,  137  which are upward extensions of the slots  130 ,  132 . The slots  130 ,  132  and their extensions  135 ,  137  are widely spaced from one another but are nonetheless not diametrically apart from one another. Since the valve assembly  62  is adapted to dispense a volume of liquid incrementally changeable through eight different increments, the slots  130 ,  132  and grooves  135 ,  137  are angularly spaced from one another by 157.50 degrees in one direction and 202.50 degrees in the opposite direction, as shown in  FIG. 6F  for the reason set forth further below. 
   Referring to  FIGS. 4 ,  5 ,  6 ,  6 A,  11 ,  11 A, and  11 B, fitted around the tubular central portion  78  to the housing  69  is a rubberized generally cylindrical refill port seal  134  having an elastomeric tubular body  136  sized to fit around the tubular central portion  78  of the housing  69  between the lower surface of the flange  67  and the upwardly extending annular shoulder  76 . At the upper end of the tubular body  136  is a radial flange  138  which engages the lower surface of the radial flange  67  as shown in FIG.  3 . Extending through the walls of the tubular body  136  are a pair of opposing tubular nipples  140 ,  142  the outer surfaces of which are adapted to fit within the refill ports  80 ,  82  of the housing  69  and create a seal against the tubular portion  120  of the stem  102  when the stem  102  is in the depressed condition as is further described below. 
   Referring to  FIGS. 4 ,  5 ,  6 B,  12 ,  12 A, and  12 B, fitted within the cylindrical inner wall  94  of the housing  69  is an axially moveable piston  144 . Across the open lower end  72  of the housing  69  and below the piston  144  is a flexible, generally circular diaphragm  146  having a cylindrical outer ridge  148  that fits around the reduced diameter cylindrical lip  86  below the downwardly facing shoulder  84  of the housing  69 . The central portion of the diaphragm  146  is bonded to the lower surface of the piston  144 , such that the piston  144  is retained to the central portion of the diaphragm  146 . As can be seen, the cylindrical inner wall  94  of the housing  69 , the upper end of the invaginations  100 ( 1 )- 100 ( 8 ) thereof, and the upper surface of the piston  144  form a cavity  145 , the volume of which becomes reduced as the piston  144  moves upwardly within the cylindrical wall  94 . 
   Referring to  FIGS. 4 ,  5 ,  6 B,  7 B,  7 D, and  8  through  8 D, fitted within the cavity  145  between the invaginations  100 ( 1 )- 100 ( 8 ) in the housing  69  and the piston  144  is a generally tubular float  154  having an upper end  156  and a lower end  158 . The float  154  has a generally tubular central body  160 , the outer diameter of which is sized to slideable fit within the lower tubular portion  128  of the stem  102 . Extending along the outer surface of the tubular central body  160  are a pair of longitudinal ribs  162 ,  164  which are not diametrically apart from one another, but are spaced an angular distance of 157.50 degrees in one direction and 202.50 degrees in the opposite direction as best shown in FIG.  8 C. At the lower end  158  of the central body  160  is a radial flange  166  having circular periphery, the diameter of which is significantly less than the outer diameter of the piston  144 . Extending forward of the radial flange  166  are a pair of poles  168 ,  170  with each pole  168 ,  170  spaced radially outward of one of the ribs  162 ,  164  such that the poles are angularly spaced from one another by an angular distance of 157.50 degrees in one direction and 202.50 degrees in the opposite direction. 
   Extending radially through the axis  174  of the lower third of the float  154  is a transverse slot  176  which divides the radially flange  166  in half, leaving each of the two poles  168 ,  170  approximately centered on each of the two halves of the divided flange  166 . As best shown in  FIGS. 8C and 8D , at the very center of the flange  166 , the slot  176  has an enlargement  178 . As best shown in  FIGS. 4 ,  5 ,  8 B,  8 C, and  12 , passing through the enlargement  178  is an upwardly extending protrusion  180  from the piston  144 . The protrusion  180  has a radial flange  182  at the upper end thereof such that when the two halves of the radial flange  166  will snap around the protrusion  180 . The flange  182  on the piston  144  will thereby lock the float  154  to the piston  144  for axial movement therewith, while allowing the float  154  to rotate around the protrusion  180  with a minimal resistance from the piston  144 . 
   The length of the float  154  is such that when the piston  144  is at its lowest position within the cavity  145 , the upper end  156  of the float  154  will fit within the lower tubular portion  128  of the stem  102 . The ribs  162 ,  164  on the float  154  will slideably fit within the longitudinal slots  130 ,  132  of the stem  102  such that the float  154  is locked for rotation with the stem  102  but is axially moveable within the cavity  145  independent of the movement of the stem  102 . 
   Referring to  FIGS. 3 ,  4 ,  5 ,  7 , and  13 , the actuator cap  53  is generally cylindrical in shape with a tubular dispensing nozzle  54  extending radially outward from the upper end thereof. The actuator cap  53  has a bore  184  extending into the lower end thereof, the cross-section of which is complementary to the cross-section of the upper end of the stem having the flat  106  thereon, such that the nozzle  54  can be positioned in only one orientation with respect to the upper end of the stem  102 . The actuator cap  53  has a passage  186  extending from the upper end of the bore  184 , through the body of the cap  53  and through the center of the discharge nozzle  54  for discharging pressurized liquid from within the cavity to the ambient. 
   As previously described, the invaginations  100 ( 1 ) to  100 ( 8 ) in the surface of the housing  69  are arranged in pairs where the members of each of the pairs are not diametrically apart from one another, but at an angle with respect thereto of 157.50 degrees in one direction and 202.50 degrees in the opposite direction, which corresponds to the angular orientations of the poles  168 ,  170  of the float  154 . 
   As shown in  FIGS. 2 ,  6 ,  6 A,  6 B,  6 C and  6 F, printed on the upper portion  55  of the housing  69  adjacent each of the notches  57  are markings  58  indicating the dosage to be discharged when the actuator cap  53  is positioned with the nozzle  54  to be received in the associated notch  57 . The flat  106  positions the actuator cap  53  with respect to the stem  102  and the longitudinal slots  130 ,  132  through the tubular portion  128  of the stem  102  retain the ribs  162 ,  164  of the float  154  such that the poles  168 ,  170  will engage one of the pairs of invaginations  100 ( 1 )- 100 ( 8 ) that correspond to the markings  58  numbered from  1  to  8  on the outer surface of the upper portion  55  of the housing  69 . For example, when the cap  53  is rotated until the nozzle  54  will be received in the notch  57  bearing the marking  58  of number “1”, the poles  168 ,  170  of the float  154  will be aligned to engage the pair of invaginations  100 ( 1 ). Rotating the cap  53  until the nozzle  54  be received in the notch  57  bearing the marking  58  of number “2” will cause the float  154  to be rotated within the housing  69  until poles  168 ,  170  are aligned to engage the invaginations  100 ( 2 ). In similar fashion rotation of the cap  53  until the nozzle  54  will be received by any other numbered notch  57  will cause the poles  168 ,  170  to engage the corresponding invagination  100 ( 1 )- 100 ( 8 ). 
   The float  154  is longitudinally moveable upward in the housing  69  until the poles  168 ,  170  engage the ends of the invaginations  100 ( 1 )- 100 ( 8 ) with which they are aligned. Referring more specifically to  FIGS. 6B and 6C , each of the pairs of vaginations  100 ( 1 )- 100 ( 8 ) has a unique overall length, and accordingly the float  154  has a different length of travel when engaged with each of the pairs of invaginations  100 ( 1 ) through  100 ( 8 ). The pair of invaginations numbered  100 ( 8 ) allow the longest length of travel and the invaginations numbered  100 ( 1 ) allow the shortest length of travel of the float  154  and the piston  144  attached thereto. A longer stroke of the float  154  and the piston  144  expels a greater amount of liquid through the valve  56  than does a shorter stroke of the float  154  and the piston  144 . 
   Referring to  FIGS. 4 ,  5 ,  13 ,  13 A, and  13 B, an upper coil spring  190  has a lower end that rests against the radial flange  98  retaining the inner retainer  88  and the upper end that rests against the actuator cap  53  for urging the actuator cap  53  and the stem  102  attached thereto in a upward direction. A second lower coil spring  192  extends around the outer circumference of the float  154  with the upper end thereof against a portion of the housing  66  and the lower end thereof resting upon the upper surface of the piston  144  for urging the piston  144  and the float  154  in a downward direction. Extending around the outer periphery of the housing  69  is a tubular plastic shell  194  having a plurality of openings  196 ,  198 ,  200 ,  202  in the walls thereof for allowing liquid  64  inside the bag  63  to pass therethrough and into the refill ports  80 ,  82  of the valve  56 . 
   Referring to  FIG. 3 , the propellant  65  within the container  52  compresses the bag  63  containing the liquid  64  around the valve  56 . To actuate the dispenser  50 , the actuator cap  53  is rotated until the nozzle  54  points to the notch  57  for the dosage of liquid that is desired to be dispensed. Thereafter, the actuator cap  53  is pressed downwardly compressing the upper spring  190 . As the stem  102  moves downwardly, the cylindrical outer wall  120  of the stem moves across the refill ports  80 ,  82  thereby sealing the cavity  145  from the liquid  64  in the bag  63 . As the stem  102  is further depressed the opening  114  in the wall of the stem  102  moves below the annular seal  90  allowing the passage  112  to communicate with the cavity  145  such that pressurized liquid  64  in the cavity  145  can escape through the passage  112  to the ambient. Pressure within the container  52  will force the piston  144  to move upward through the cylindrical inner wall  92  and compress the lower spring  192  until the poles  168 ,  170  engage the invaginations  100 ( 1 )- 100 ( 8 ) corresponding to the notch  57  into which the nozzle  54  of the actuator cap  53  is received. The movement of the piston  144  expels liquid in the cavity  145  through the passage  112  in the stem  102 . The actuator cap  53  is held in the depressed condition until the poles  168 ,  170  of the float  154  engage the associated invaginations  100 ( 1 )- 100 ( 8 ) after which the actuator cap  53  is released. When the actuator cap  53  is released, the upper spring  190  urges the cap  53  and the stem  102  upwardly the refill ports are again opened. Further upward movement of the stem  102  causes the discharge ports  114  to again be sealed by the tubular seal  90  preventing further discharge of liquid. The second coil spring  192  urges the piston  144  downward causing liquid  64  from the bag  63  to pass through the ports  80 ,  82  along the longitudinal indentations  122  and into the cavity  145  allowing the cavity  145  to be refilled. 
   Referring to  FIGS. 2 and 3 , a desirable feature of the present invention is that upper portions  55  of the valve  56  extend outward of the ferrule  66 , which is crimped around the radial flange  67  of the housing  69 . An O-ring  68  positioned at the opening of the container  52  and a bead surrounding the opening of the bag  63  after which the ferrule  66  is crimped, sealing the container  52  and the bag  63  around the circumference of the valve assembly  54 . 
   Another advantage of the valve assembly of the present invention is that by virtue of positioning the poles  168 ,  170  so as not to be at 180 degrees from one another, the actuator  53  can be rotated to notches  57  that are angular spaced by 180 degrees from one another and discharge different volumes of liquid. The dispenser  50  is depicted as having eight different notches  57 , with each notch dispensing a different dosage of liquid  64 . The dispenser  50  could easily be made with ten notches  57  so if the volume of liquid being dispensed could be divided into increments of tenths or in such other fractions as may be desirable. 
   While the present invention has been described with respect to a single embodiment, it will be appreciated that many modifications and variations may be made without departing from the true spirit and scope of the invention. It is therefore the intent of the dependent claims to cover all such variations and modifications, which fall within the true spirit and scope of the invention.