Unit dose dispenser

A unit dose liquid dispenser includes a resilient metering reservoir disposed within a main reservoir in which a large supply of the liquid is maintained under pressure. Depression of an actuator to a dispensing position connects the metering chamber to the ambient while sealing it from the main reservoir resulting in the collapse of the metering reservoir and expulsion of the contents to the atmosphere at the pressure in the main reservoir.

The present invention relates in general to a device for dispensing a 
premeasured dose of liquid from a reservoir containing a larger supply of 
the liquid, and it relates in particular to a new and improved dispenser 
in which the liquid supply is maintained under pressure and the 
premeasured dose is dispensed at a predetermined pressure. 
BACKGROUND OF THE INVENTION 
Finger operated pumps for dispensing small amounts of liquid from a 
container are well known. See, for example, U.S. Pat Nos. 3,001,524 and 
3,452,905. Such pumps are relatively complex and do not dispense a 
predetermined amount of liquid because the amount of liquid dispensed upon 
each actuation of the pump depends on the way in which the pump is 
actuated, i.e., the speed and stroke of the actuator affect the quantity 
of the liquid dispensed. 
Particularly where medicaments are to be dispensed, it would be desirable 
to provide a mechanism which dispenses a predetermined quantity of liquid 
every time the dispenser is actuated irrespective of the force applied to 
the actuator. 
SUMMARY OF THE INVENTION 
Briefly, there is provided in accordance with the teachings of the present 
invention a new and improved unit dose liquid dispenser in which a supply 
of liquid is held under pressure in an elastomeric main reservoir, and a 
premeasured dose of the liquid is dispensed at the pressure of the liquid 
in the main reservoir upon each actuation of an actuator. In a preferred 
embodiment a second resilient and collapsible metering reservoir is 
located within the main elastomeric reservoir and is collapsed by the 
pressure within the main reservoir when the actuator connects the metering 
chamber in the collapsible metering reservoir to the ambient thereby 
dispensing the entire contents of the metering chamber at a predetermined 
pressure.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring particularly to FIG. 1, a unit dose liquid dispenser 10 includes 
a generally cylindrical container 12 to the top of which is mounted a 
combined spray head and actuator 14. Depression of the head 14 causes the 
dispensing of a premeasured quantity of liquid in spray form at a 
predetermined pressure. 
Referring now to FIGS. 2, 3 and 4, it may be seen that the container 12 
houses a main reservoir 15 which includes an expandable and collapsible 
inner container 16 which is enclosed by an elastomeric sleeve 18. The 
sleeve 18 is shown in the expanded condition wherein it exerts a 
substantially constant compressive force on the contents of the container 
16. A pressurized reservoir of this type is described in greater detail in 
U.S. Pat. No. 4,387,833. 
As best shown in FIG. 3 the container 16, which is preferably blow molded, 
is formed of plastic and includes a tubular neck section 20 having an 
external annular flange 22 near the top. A counterbore 24 is provided at 
the top of the neck section 20 which is defined by a raised annular bead 
26. A generally tubular valve housing member 28 has an external annular 
flange 30 at the top which seats in the counterbore 24. An annular gasket 
32 is positioned over the top of the bead 26, and a raised lip 34 disposed 
at the outer edge of the flange 30 on a locking ring 36 formed of metal 
compresses the gasket 32 against the top surfaces of the bead 26 and the 
lip 34 and holds the housing in assembled relationship to the neck of the 
container 16. 
A locking cap 38 is snap fitted over the locking ring 36 and the upstanding 
neck portion of the outer housing 12. As shown, an external annular flange 
40 at the top of the container 12 seats against the bottom of the ring 36, 
and an internal annular bead 42 on the cap 38 extends under the flange 40 
while an internal annular flange portion 44 at the top seats against the 
top of the ring 36. 
A valve stem 50 is slidably fitted in an axial bore 52 in the tubular 
housing member 28 and extends upwardly through a central opening 54 in the 
ring 36. The stem 50 has a reduced diameter section 56 which extends 
downwardly through a narrow bore 58 at the bottom of the housing 28. A 
flat washer 60 is slidably fitted over the reduced diameter section 56 
over an annular gasket 62 which rests on an annular shoulder 64 on the 
housing 28. A coil spring 66 surrounds the stem 50 and is positioned 
between the washer 60 and a downwardly facing annular shoulder 68 at the 
junction of the large and small diameter sections of the stem 50 to urge 
the stem in an upward direction to the standby position shown in FIG. 3. 
Fixedly secured over the tubular lower end portion 70 of the housing member 
28 is an elastomeric, generally tubular reservoir member 72 which is shown 
in FIG. 3 in its relieved, unstressed condition. In its unstressed 
condition the elastomeric member 72 encloses a somewhat spherical metering 
chamber 74 through which the lower end portion of the stem 50 slidably and 
sealably extends. As may be seen in FIG. 3, the lower tubular end of the 
reservoir member 72 is sealably bonded to a tubular sleeve 76 through 
which the thin, cylindrical lower end section 78 of the stem 50 slidably 
extends. An O-ring type sealing ring 80 is tightly fitted in a counterbore 
82 and a cap 84 is bonded to the lower end of the stem 50. The cap has an 
upwardly extending tubular section which slidably fits into the 
counterbore 82 to hold the sealing ring 80 in compression when the stem 50 
is in the up position as shown in FIG. 3. 
In order to permit some of the liquid 85 which fills the container 16 to 
fill the unit dose metering chamber 74 when the stem 50 is in the standby 
position shown in FIG. 3, the stem 50 is provided with an axial passageway 
86 which extends from the bottom end thereof to a location where it opens 
onto a transverse passageway 88 which itself opens into the chamber 74 
when the stem 50 is in its upward position. Because of the memory of the 
elastomeric reservoir member 72 and the fact that there is no pressure 
differential across it, when the stem 50 is in the upward standby position 
shown in FIG. 3, the member 72 returns to its unstressed state and liquid 
85 flows into the metering chamber to fill it with a predetermined dose of 
liquid. 
When the spray head actuator 14 is depressed, the stem 50 is moved 
downwardly to the position shown in FIG. 4 wherein the unit dose metering 
chamber 74 is communicated to the ambient by interconnected passageways 90 
and 92 in the stem 50. The passageway 90 extends transversely through the 
stem 50 and the passageway 92 extends axially from the passageway 90 to 
the upper end of the stem 50 where it connects to a dispensing orifice 94 
in the spray head 14. As the stem 50 is moved down, the passageway 72 
moves out of the chamber 74 to seal the metering chamber 74 from the main 
reservoir chamber while the passageway 90 moves into the metering chamber 
74 to communicate it to the ambient. With the metering chamber 74 open to 
the ambient via the passageways 90 and 92 and the orifice 94, the pressure 
in the main reservoir collapses the reservoir 72 to force the entire 
contents of the metering chamber 74 into the ambient at the pressure in 
the main reservoir. 
The reservoir 15 maintains its contents at a substantially constant 
pressure as the contents are dispensed. Initially, the pressure is at a 
maximum, drops off to about 85 percent of the initial pressure after about 
10 percent of the contents have been dispensed, and remains at that second 
pressure until about 90 percent of the contents have been dispensed. The 
pressure then drops off as the last 10 percent of the contents are 
dispensed. 
The dispenser of the present invention has many different applications and 
may, for example, be used with a nebulizer orifice for spraying 
predetermined quantities of a liquid directly into the nasal passages of a 
patient at a substantially predetermined pressure. 
While the present invention has been described in connection with a 
particular embodiment thereof, it will be understood by those skilled in 
the art that many changes may be made without departing from the true 
spirit and scope of the present invention. Therefore, it is intended by 
the appended claims to cover all such changes and modifications which come 
within the true spirit and scope of this invention.