Abstract
A discharging device for liquids. The invention relates to a discharging device for liquids, more particularly for pharmaceutical liquids, comprising a delivery device (10), a liquid storage receptical (20) communicating with an input (10a) of the delivery device for storage of the liquid (30), and a discharge orifice (12) which communicates with an outlet (10b) of said delivery device, and the liquid storage receptical (20) is at least in part in the form of a dimensionally flexible liquid-containing bag (20) and the liquid storage receptical (20) is disposed in a buffer chamber of constant volume (42). To prevent air from escaping from the buffer chamber (42), provision is made for the buffer chamber to be sealed by a protective housing from the environment (1) in a gas-tight manner, for the buffer chamber to communicate with the environment through at least one capillary passageway for the purpose of pressure compensation, or for the buffer chamber (42) to communicate with the environment (1) via a balancing passageway for the purpose of pressure compensation, while a valve (70) which opens in dependence on the pressure differential is disposed in this balancing passageway.
Claims
1. A discharging device for liquids, comprising: a delivery device, an outer housing defining a buffer chamber, a liquid storage receptacle that communicates with an inlet of said delivery device and is adapted to store liquid, and a discharge orifice communicating with an outlet of said delivery device, wherein said liquid storage receptacle is at least in part in the form of a dimensionally flexible liquid-containing bag, and said liquid storage receptacle is disposed in the buffer chamber of constant volume, wherein said buffer chamber permanently communicates with the environment through at least one capillary passageway for the purpose of balancing the pressure, the capillary passageway being configured such that air in the buffer chamber remains saturated with liquid, the capillary passageway having a length-divided-by-average-cross-sectional-area quotient greater than 1000 mm.sup.1, and is, at least in part, a groove defined between a portion of the liquid storage receptacle and a portion of the outer housing.
2. The discharging device according to claim 1, wherein said capillary passageway has an elongated, narrow form, and the average cross-sectional area of said capillary passageway is less than 0.05 mm.sup.2.
3. The discharging device according to claim 1, wherein said capillary passageway is in a region jointly sealed off by a protective housing and said liquid storage receptacle.
4. The discharging device according to claim 1, wherein said groove extends at least in part in the form of an arc or spiral on the external surface of said liquid storage receptacle.
5. The discharging device according to claim 1, wherein said buffer chamber is delimited relative to the environment by a wall made of a material displaying a low diffusion rate.
6. The discharging device according to claim 1, wherein on said liquid storage receptacle a radially outwardly oriented fin is provided, which performs the function of a gasket between said buffer chamber and a housing part containing said delivery device.
7. The discharging device according to claim 2, wherein the average cross-sectional area of said capillary passageway is less than 0.02 mm.sup.2.
8. The discharging device according to claim 7, wherein the average cross-sectional area of said capillary passageway is less than 0.01 mm.sup.2.
9. The discharging device according to claim 1, wherein the length of the capillary passageway is greater than 10 mm.
10. The discharging device according to claim 9, wherein the length of the capillary passageway is greater than 30 mm.
11. The discharging device according to claim 10, wherein the length of the capillary passageway is greater than 50 mm.
12. The discharging device according to claim 5, wherein the material of the wall comprises at least one of metal, ceramic, and glass.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Additional aspects and advantages of the invention are revealed by the claims and the following description of preferred exemplary embodiments of the invention that are explained below with reference to the figures, in which:
(2) FIGS. 1a and 1b show a first embodiment of a discharging device of the invention,
(3) FIGS. 2a, 2b, and 3 show a second embodiment of a discharging device of the invention,
(4) FIGS. 4a, 4b, and 5 show a third embodiment of a discharging device of the invention,
(5) FIGS. 6a and 6b show a fourth embodiment of a discharging device of the invention, and
(6) FIGS. 7a, 7b, and 8 show a fifth embodiment of a discharging device of the invention.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
(7) The discharging devices of the invention shown in the figures are each in the form of portable discharging devices and they each comprise, as common characteristics, a manually operable delivery device 10, the inlet side 10a of which is connected to a liquid storage receptical 20 and the outlet side 10b of which is connected to a discharge orifice 12. In the case of the embodiment shown in FIGS. 1 to 3, the delivery device 10 is in the form of a piston pump. In the case of the embodiments shown in FIGS. 4 to 7, the delivery device 10 is in the form of a bellows pump. Furthermore, all embodiments are equivalent to the effect that the liquid storage receptical 20 is in the form of a liquid-containing bag of a flexible nature so that its internal volume can be adapted to suit the amount of liquid 30 that is present in the liquid storage receptical 20 and that is to be discharged. Furthermore, the common feature of the discharging devices of all of the embodiments is that the bag-type liquid storage receptical 20 is disposed in a buffer chamber 42 formed by a protective housing 40 and thus protected from external mechanical influences.
EMBODIMENTS IN DETAIL
(8) FIG. 1a shows the first embodiment in the delivered state. In this delivered state, the liquid storage receptical 20 has a maximum volume that is such that the liquid storage receptical 20 fills only about 50% of the buffer chamber 42. In this delivered state, that portion 42a of the buffer chamber 42 that is not occupied by the liquid storage receptical is filled with air under approximately ambient pressure (1 bar).
(9) In this and all other embodiments, the liquid storage receptical 20 is only connected to the delivery device 10 such that the liquid 30 present in the liquid storage receptical 20 can escape, at least in liquid form, from the liquid storage receptical 20 only in the direction of the delivery device 10. In the embodiment shown in FIGS. 1a and 1b and likewise in all of the embodiments illustrated, there is no possibility for ambient air in an environment 1 to enter the liquid storage receptical 20 itself. The liquid storage receptical 20 is sealed off from the environment by means of a circumferential collar 22 provided at the upper end of the liquid storage receptical 20 and clamped between an upper edge 44 of the receptical 40 and a delivery housing 14 to act as a seal.
(10) Furthermore, in the embodiment shown in FIGS. 1a and 1b, this seal also causes that portion 42a of the buffer chamber 42 that is filled with air to be sealed off in a gas-tight manner relatively to the environment 1 so that external air can enter neither the liquid storage receptical 20 nor that portion 42a of the buffer chamber 42 that is not occupied by the liquid storage receptical 20.
(11) When the discharging device shown in FIGS. 1a and 1b is put into action in that liquid 30 is discharged by manually operating the delivery device 10 by means of the manual actuator 16, the internal volume of the liquid storage receptical 20 is reduced while the surrounding portion 42a of the buffer chamber 42 is necessarily increased. Since no air can flow into the discharging device, this gradually results in a reduction of the pressure prevailing in the buffer chamber 42. This pressure decrease is of only small significance due to the fact that a considerable amount of air is already present in the buffer chamber 42 in the delivered state shown in FIG. 1a. When the liquid storage receptical 20 is completely empty, the pressure in the buffer chamber is about 0.5 bar. Since the delivery device 10 is designed such that it can work while counteracting such a low pressure, the operational reliability of the discharging device is always assured.
(12) FIG. 1b shows an intermediate state in which half of the liquid 30 has been discharged and the pressure in the buffer chamber 42 is about 0.8 bar, that is, a vacuum of about 0.2 bar prevails relative to the environment.
(13) As a result of the complete isolation of the buffer chamber 42 relative to the environment 1, the design shown in FIGS. 1a and 1b allows only small amounts of the liquid 30 to diffuse through the wall of the liquid storage receptical 20 into the region 42a of the buffer chamber 42. The air in the portion 42a very rapidly becomes saturated so that this diffusion process ceases. Since the saturated air cannot escape due to the fact that the buffer chamber 42 is sealed off in a gas-tight manner from the environment 1, only a small amount of liquid 30 can pass into the region 42a of the buffer chamber 42.
(14) The embodiment shown in FIGS. 2a and 2b is much the same as the embodiment shown in FIGS. 1a and 1b. However, this embodiment differs from the first embodiment in that a capillary passageway 60 is provided, a portion 60a of which extends from the environment 1 to the collar 22 of the liquid storage receptical 20. As shown in FIG. 3, a groove is provided in this collar 22, to form an outwardly oriented portion 60b, a tangentially extending portion 60c and a radially inwardly oriented portion 60d of the capillary passageway 60. The open side of this groove is closed by the upper edge 44 of the receptical 40. Air can enter the region 42a of the buffer chamber 42 through the capillary passageway so that pressure equalization can take place as the liquid storage receptical 20 is progressively emptied. The ambient pressure of about 1 bar is thus re-established in the buffer chamber 42 shortly after each operation of the discharging device. The path of the air through the capillary passageway 60 is illustrated by the dotted arrow 2 shown in FIG. 2b.
(15) Thus in this embodiment shown in FIGS. 2a, 2b, and 3, there is communication between the environment 1 and the buffer chamber 42. However, since this communication takes the form of a capillary passageway 60, it does not allow the liquid that has diffused from the liquid storage receptical 20 into that region 42a of the buffer chamber 42 that is not occupied by the liquid storage receptical 20 to escape into the environment 1. Instead, a stable gradient is established in the capillary passageway 60 between the saturated air in the region 42a and the air in the environment 1, which gradient allows the liquid 30 that has diffused from the liquid storage receptical 20 to escape from the portion 42a of the buffer chamber 42 in negligible amounts only.
(16) The embodiment shown in FIGS. 4 and 5 illustrates a dispenser that differs decidedly from the preceding embodiments in terms of the basic construction and yet follows a similar basic principle with regard to the aeration of that region 42a of the buffer chamber 42 that is not occupied by the liquid storage receptical 20. Here again, a capillary passageway 62 is provided, the first segment 62a of which extends between two housing portions 14 and 40. The segment 62a adjoins a segment 62b of the capillary passageway, which is in the form of a spiral groove in the external surface of the liquid storage receptical 20 and the open side of which is closed by the inside surface of the protective housing 40.
(17) The purpose of this capillary passageway 62 is the same as that of the capillary passageway 60 of the embodiment shown in FIGS. 2a, 2b, and 3. The air from the environment 1 can enter the buffer chamber 42 along the path of the dotted arrow 4. The distinctive feature of this embodiment consists particularly in the increased length of the capillary passageway 62 as a result of its spiral shape.
(18) In the embodiment shown in FIGS. 6a and 6b, provision is again made for the decrease in volume of the liquid storage receptical 20 caused by the discharges of the liquid 30 to be compensated for a subsequent flow of air into that portion 42a of the buffer chamber 42 that is not occupied by the liquid storage receptical 20. However, this is achieved, not by a capillary passageway, but instead by a valve 70 which opens in dependence on the prevailing pressure. The valve comprises a dome-shaped valve diaphragm 70a that is slotted in its domed region. When the volume of the liquid storage receptical 20 decreases due to the discharge of liquid, a negative pressure develops in the region 42a in relation to the environment 1. When the pressure difference between the air in the region 42a and the environment 1 exceeds 0.2 bar, the valve 70 opens in the manner shown in FIG. 6b and permits an inflow of air along the path of the arrow 6. However, the liquid that diffuses through the wall of the liquid storage receptical 20 into the region 42a to cause saturation of the air in this region cannot escape from the buffer chamber 42 so that, in this embodiment also, only a small amount of liquid 30 will be lost to the environment 1.
(19) The embodiment shown in FIGS. 7a, 7b and 8 is closely related to the one shown in FIGS. 6a and 6b in terms of its mode of operation. However, in this last embodiment, the valve 72 is not formed by a separate diaphragm but by a closing lip 72a extending around the circumference of the liquid storage receptical 20 on the outside surface thereof. This closing lip 72a rests against an inside surface of the receptical protective housing 40 when the pressure difference between the buffer chamber 42 and the environment 1 is less than 0.2 bar so that no air can escape from the region 42. This is shown in FIG. 7a. Only when a negative pressure of more than 0.2 bar is created in the region 42a due to of the discharge of liquid 30 from the liquid storage receptical 20, the closing lip 72a temporarily moves away, at least partly, from the inside surface protective housing 40 of the receptical and thus makes way for the inflow of air that travels along path indicated by the arrow 8, i.e. from the environment 1 to the region 42a of the buffer chamber 40.
