GB2348676A

GB2348676A - Measuring pressurised container contents by balancing

Info

Publication number: GB2348676A
Application number: GB9907925A
Authority: GB
Inventors: David Howlett; Christopher John Eames; Paul Michael Allsop; John David Clark
Original assignee: Bespak PLC
Current assignee: Consort Medical PLC
Priority date: 1999-04-07
Filing date: 1999-04-07
Publication date: 2000-10-11
Also published as: GB9907925D0

Abstract

Apparatus for determining product quantity in a pressurised dispensing container comprises: a housing for receiving a container; a fulcrum for balancing the housing and means for adjusting relative housing and fulcrum positions. Product quantity is determinable from relative housing and fulcrum positions when balanced. Embodiments include: a longitudinal serrated strip (26 Figs. 1) and scale (29) on the housing (21) balanced on a removable mouthpiece cap (23); a graduated scale component (40 Figs. 2) having a rounded portion (46) attached to the housing and has a slide (43) with a fulcrum mounted thereon; a rotatable stand (61 Figs. 3) having arms (62) slidable in housing slots (60); a detachable stand 71 with rounded arms 72 engaging a graduated 29 housing flange; an arcuate balancing segment (80, 90 Figs. 5) with ribs forming respective fulcra attachable to the housing or the container.

Description

IMPROVEMENTS IN OR RELATING TO DISPENSING APPARATS The present invention relates to improvements in dispensing apparatus and, in particular, to improvements in apparatus providing means for measuring the quantity of product remaining in a pressurised dispensing container.

Pressurised dispensing containers are widely used in the pharmaceutical industry for storing medications and other products to be dispensed in aerosol form.

Such containers usually contain a propellant, such as HFC 134a, in which the product is suspended or dissolved. Solvents, such as ethanol, may also be present in the formulation. It is known to provide pressurised dispensing apparatus capable of dispensing metered doses of product from the containers upon each actuation of the container valve, for example, metered dose inhalers. The reliability and consistency of the metered dose is especially important where the product comprises or includes a medication. Inconsistent or unreliable dispensation could result in a user of the dispensing apparatus receiving too great or too little medication.

A problem found by many users of such apparatus is the inability to determine the quantity of product remaining in the container. Many types of apparatus continue to allow the dispensing of quantities of propellant and/or solvent when the container is near empty, even though the dose of product contained in the propellant is below the required level, thereby exacerbating the problem. Thus, users are often unaware that the dispensing apparatus is operating inadequately. This has potentially dangerous consequences where the product or medication dispensed is required urgently and no time is available to locate a replacement dispenser, such as in the treatment of asthmatic conditions. Sufferers of asthma often carry dispensers with them for extended periods of time, which may only be used on an occasional basis. Therefore, there is a danger that, where the user is unable to determine the contents of the pressurised dispensing container and the device is required in an emergency situation, the contents of the container may be inadequate.

It is an object of the present invention to provide apparatus for quickly and easily determining the quantity of product remaining in a pressurised dispensing container without the need for special testing equipment. Also, to provide apparatus suitable for use with conventional pressurised dispensing containers.

Accordingly, the present invention provides apparatus for determining the quantity of product contained in a pressurised dispensing container, said apparatus comprising a housing for receiving a pressurised dispensing container, at least one fulcrum about which the housing is pivotable and means for enabling the relative position of the housing to the at least one fulcrum to be adjusted, wherein the quantity of product in a pressurised dispensing container is determinable from the relative position of the housing to the at least one fulcrum when the clockwise rotating moment acting on the housing with a pressurised dispensing container located therein equals the anti-clockwise rotating moment such that the housing is balanced on the at least one fulcrum.

The housing may be provided with markings, the quantity of product contained in the pressurised dispensing container being determinable from the relative position of the markings and the at least one fulcrum.

In one embodiment, the at least one fulcrum is movable relative to the housing along a longitudinal axis thereof.

In one embodiment, the at least one fulcrum is provided by a member pivotally attached to the housing.

In another embodiment, the at least one fulcrum is provided by a member removably attachable to the housing.

The means for enabling the relative position of the housing to the at least one fulcrum to be adjusted may be provided by teeth on an external surface of the pressurised dispensing container receiving portion, said teeth having valleys therebetween, wherein a rim of the mouthpiece cover is locatable in said valleys.

Alternatively, the at least one fulcrum is slidable along at least a length of the housing to provide the means for enabling the relative position of the housing to the at least one fulcrum to be adjusted. The housing may further comprise a fixed support member located towards an end of the housing, said at least one fulcrum being slidable towards and away from the support member. The at least one fulcrum may be provided by an attachment which is formed separately from the housing and is fixed thereto by means of co-operating formations.

Optionally, the fixed support member is located on the attachment. Preferably, the attachment is transparent, and is located over markings on the housing relating to quantities of product.

In another embodiment, the housing is provided with longitudinal slots and the fulcrum member comprises arms which are slidable along the slots.

In another embodiment, the fulcrum member comprises two arms on which the housing may be supported by means of two laterally extending flanges, one on either side of the housing.

In a further embodiment, the apparatus further comprises a plurality of fulcra, wherein the means for enabling adjustment of the relative position of the housing to the fulcra comprise an arcuate member on which the plurality of fulcra are provided. The arcuate member may be provided by arcuate shaping of the housing.

The present invention also provides a method of determining the quantity of product contained in a pressurised dispensing container comprising the steps of locating the pressurised dispensing container in a housing, placing the housing such that it is supported on at least one fulcrum, adjusting the relative position of the housing to the at least one fulcrum until the clockwise rotating moment acting on the housing equals the anti-clockwise rotating moment such that the housing is balanced on the at least one fulcrum and determining the quantity of product in the pressurised dispensing container from the relative position of the housing to the at least one fulcrum.

In one embodiment, the balancing of the housing is achieved by moving it relative to the at least one fulcrum by incremental amounts.

In another embodiment, the balancing of the housing is achieved by sliding at least one fulcrum relative to the housing along a longitudinal axis thereof.

In a further embodiment, the balancing of the housing is achieved by placing it on a flat surface and allowing the housing to pivot about a series of successive fulcra positioned along an arcuate surface.

Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which: Figure la is a sectional side elevation of a first embodiment of dispensing apparatus according to the present invention; Figure lb is a perspective view of the apparatus of Figure la; Figure lc is another perspective view of the apparatus of Figure la; Figure ld is a side elevation of the apparatus of Figure la in use; Figure 2a is a sectional elevation of a second embodiment of dispensing apparatus according to the present invention; Figure 2b is a perspective view of the apparatus of Figure 2a; Figure 2c is an exploded perspective view of the apparatus of Figure 2a; Figure 2d is a side elevation of the apparatus of Figure 2a in use; Figure 2e is a perspective view of the apparatus of Figure 2a; Figure 3a is a sectional elevation of a third embodiment of dispensing apparatus according to the present invention; Figure 3b is a perspective view of the apparatus of Figure 3a; Figure 3c is a perspective view of the apparatus of Figure 3a in use; Figure 3d is a perspective view of the apparatus of Figure 3a; Figure 4a is an exploded perspective view of a fourth embodiment of dispensing apparatus according to the present invention; Figure 4b is a perspective view of the apparatus of Figure 4a in use; Figure 5a is a side elevation of a fifth embodiment of dispensing apparatus according to the present invention; Figure 5b is a side elevation of an alternative version of the apparatus of Figure 5a.

The following embodiments of the present invention are described for use in combination with a pressurised dispensing container 1 of known design. A typical pressurised dispensing container 1 has a metering valve secured to a can, for storing the product for dispensing, by means of a crimped ferrule.

The valve has a valve stem 3 projecting therefrom.

Depression of the valve stem 3 relative to the container actuates the valve mechanism to dispense a metered dose of product through an outlet of the valve stem.

Figures la to ld show a first embodiment of dispensing apparatus according to the present invention. The dispensing apparatus comprises a housing 20 having a substantially cylindrical portion 21 with a major longitudinal axis, which is open at one end for receiving, in use, a pressurised dispensing container 10, and a mouthpiece 22 extending laterally from one end of the cylindrical portion 21.

Preferably, the mouthpiece 22 extends at a slight downward angle from cylindrical portion 21 as viewed in the orientation shown in Figure la.

The cylindrical portion 21 is provided with a valve stem block 24 for receiving an end of the valve stem 11 of the pressurised dispensing container 10.

The valve stem block 24 defines a duct and orifice orientated towards mouthpiece 22 such that product dispensed from the container 13 through the valve stem 11 is directed into mouthpiece 22 for inhalation by the user.

The internal workings of the pressurised dispensing container 10 and valve stem block 24 are of known design and do not form part of the present invention.

The housing 20 is provided with, on an exterior surface, a strip 26 located parallel to and between two support strips 27, which support strips 27 extend parallel to one another along a substantial part of the length of the cylindrical portion 21. The strip 26 is provided with teeth in the form of notches or serrations.

Markings 29 are provided on the housing 20 forming a graduated scale for indicating the quantity of product in the container, said markings extending along the length of the strips 26,27.

The mouthpiece 22 is closed by a cap 23 when the dispensing apparatus is not in use. The cap 23 is closed at one end and open at the other end.

Preferably, cap 23 push-fits onto the mouthpiece 22.

The closed end of cap 23 may be provided with slots to receive, in use, the support strips 27 so as to stabilise the housing 20 relative to the cap 23.

In order to determine the quantity of product in the pressurised dispensing container 10, the cap 23 must be removed from the mouthpiece 22 and placed on a flat stable surface. The housing 20, with pressurised dispensing container 10 positioned therein, is then placed lengthways on top of the cap 23 with the strip 26 in contact with the cap 23 as shown in Figure ld.

The support strips 27 provide additional support for the housing 20 in a direction perpendicular to strip 26, to prevent it toppling off the cap 23,. The housing 20 must be re-positioned relative to the cap 23, until an equilibrium point is reached just before the housing 20 begins to pivot and rotate about a fulcrum point formed by an edge of the cap 23.

Equilibrium occurs when the clockwise rotating moment acting on the housing, with the pressurised dispensing container 10 located therein, equals the anticlockwise rotating moment. The presence of the strip 26 provided with a discrete number of teeth or serrations ensures that there are only a discrete number of relative positions of the housing 20 and cap 23. This ensures that the process of finding the equilibrium point is made easier and more consistent for the user. Once the equilibrium point has been established, the user can determine the quantity of product in the pressurised dispensing container 10 by reading off the marking 29 aligned with the appropriate edge of the cap 23, as shown in Figure ld.

The quantity of product in the pressurised dispensing container 10 will alter the centre of gravity of the combined unit consisting of the housing 20 and pressurised dispensing container 10.

Therefore, since the total mass of the container and its contents varies according to the quantity of product in the container 10, the position of the centre of gravity of the combined unit of the container 10 and housing 20 can be used as a measure of the quantity of product in the container 20. The greater the quantity of product in the pressurised dispensing container 10, the further to the right (where the housing 20 and cap 23 are in the orientation shown in Figure ld) the housing 20 will need to be moved relative to the cap 23 in order to establish the equilibrium point.

Figures 2a to 2e show a second embodiment of dispensing apparatus according to the present invention. Like components of the first and second embodiments have been referenced by like numerals.

The general shape of the housing 20, having a cylindrical portion 21 and mouthpiece 22, is the same as in the apparatus of the first embodiment. A substantially flat scale component 40 is provided, having a flat elongate portion 51 and means for affixing the scale component 40 to an exterior of the cylindrical housing portion 21. Perpendicular flanges 52 at either end of the attachment 40 form detents 53 to act as the fixing means. Markings 29 are provided on a scale component 40 forming a graduated scale extending along its length. At one end of scale component 40 is located a rounded portion 46 on a side opposite flange 52. The scale component 40 is formed as a separate component from the cylindrical portion 21 during manufacture and is assembled with the cylindrical portion 21 by locating the detents 53 in complimentary apertures 42 in the cylindrical portion 21. When assembled, a gap 54 is left between scale component 40 and cylindrical portion 21 as shown in Figure 2d. The scale component 40 is orientated so that rounded portion 46 is positioned nearest the mouthpiece end of the housing 20.

Scale component 40 further comprises a slide 43, shown in Figure 2e. The slide 43 comprises a crosspiece 55 joining two arms 56, having rounded profiles 57 on one side thereof. The slide 43 is located on the elongate member 51 of scale component 40 and retained by means of lugs 45 on a side of the arms 56 opposite rounded profiles 57 which locate in the gap 54 between the scale component 40 and cylindrical housing portion 21. The slide 43 is preferably of a transparent material and has a line 47 marked on the cross-piece 55.

In order to determine the quantity of product in the pressurised dispensing container 10, a user of the apparatus moves the slide 43 along the elongate member 51 away from the rounded portion 46 and places the housing 20 with the pressurised dispensing container 10 in position on a flat stable surface such that the housing 20 is supported on the rounded portion 46 of scale 40 and the rounded profiles 57 of slide 43.

Slide 43 can then be moved along the elongate member 51 towards or away from rounded portion 46 as necessary until an equilibrium point is reached wherein the housing 20 and pressurised dispensing container 10 are balanced, just before they begin to rotate about a fulcrum point formed by the rounded profile 57. At this point, the user picks up the housing 20 and read off the quantity of product remaining using the marking 29 aligned with line 47 of slide 43.

The greater the quantity of product in the pressurised dispensing container 10 the further to the right (when the apparatus is in the orientation shown in Figure 2d) the slide 43 will need to be moved in order to achieve the required equilibrium point.

Preferably, the dimensions of the cross-piece 55 of slide 43, compared to rounded portion 46, allows the arm-portions 56 of the slide 43 to be slid over and push-fit onto the rounded portion 46 when not in use.

Figures 3 to 3d show a third embodiment of dispensing apparatus according to the present invention. Like components of the first and third embodiments have been referenced by like numerals.

The general shape of the housing 20, with a cylindrical portion 21 and mouthpiece 22, is as in the first and second embodiments.

In particular, the cylindrical portion 21 of the housing 20 is provided with two longitudinal slots 60, diametrically opposing one another, along a substantial length of the cylindrical portion 21.

Markings 29 are provided along the length of the slots 60. A rotatable stand 61, comprising a base 66, from which project a pair of arms 62, is slidably connected to the slots 60 by means of inward facing, generally circular shaped lugs 63 at the distal end of arms 62, as shown in Figure 3d. Each lug 63 is received in a respective slot 60 and is free to rotate and slide relative to the cylindrical portion 21 of the housing 20. The length of the arms 62 and shape of the base 66 are such that the stand 61 may be clipped over the end of the cylindrical portion 21 nearest mouthpiece 22 when not in use and retained there by means of a snap lock 64 or other suitable co-operating formations, as shown in Figure 3b.

In order to determine the quantity of product remaining in the pressurised dispensing container 10 a user of the device unclips the base 66 of rotatable stand 61 from the end of housing cylindrical portion 21. The base 66 is then placed on a flat, stable surface and the cylindrical housing portion 21 is rotated into a substantially horizontal orientation as shown in Figure 3c. The housing cylindrical portion 21 is then moved perpendicular to the rotatable stand 61 with the lugs 63 of arms 62 moving within slots 60 until a point is reached at which housing 20 and pressurised dispensing container 10 are balanced on the fulcrum point formed by the lugs 63. The quantity of product in the container 10 is then read off by determining which of the markings 29 along the cylindrical portion 21 is aligned with the end of the arms 62.

The greater the quantity of product in the pressurised dispensing container 10, the further to the right (where the apparatus is in the orientation shown in Figure 3c) the housing 20 will need to be moved relative to the rotatable stand 61 in order to achieve the equilibrium point.

Figures 4a and 4b show a fourth embodiment of dispensing apparatus according to the present invention. Like components of the third and fourth embodiments have been referenced by like numerals.

The general shape of the housing 20, having a cylindrical portion 21 and mouthpiece 22, is as shown in the previous embodiments.

A detachable stand 71 is provided, comprising a base 71 from which project two arms 72, having rounded ends 73. When not in use, the stand 71 may be located on the end of the cylindrical housing portion 21 at the end nearest the mouthpiece and retained there by means of a snap lock 64 or other suitable co-operating formations. The housing cylindrical portion 21 comprises two flanges 70, one on either side thereof, which extend laterally. Markings 29 are provided on a flattened front facing surface of each flange 70.

In order to determine the quantity of product in the pressurised dispensing container 10, the user removes the detachable stand 71 from the housing cylindrical portion 21 and places it on a flat stable surface. The housing 20 containing the pressurised dispensing container 10 is then positioned on the detachable stand 71 with the flanges 70 resting on the rounded ends 73 of arms 72 as shown in Figure 4b. The housing 20 is then moved relative to the stand 71 until an equilibrium point is achieved wherein the housing 20 is balanced on the fulcrum formed by the rounded ends 73. The quantity of product remaining is then read off by determining which of the markings 29 is aligned with the rounded ends 73 of the arms 72.

Figures 5a and 5b show a fifth embodiment of dispensing apparatus according to the present invention.

Like components of the first and fifth embodiments have been referenced by like numerals.

The housing 20 has a generally cylindrical portion 21 and mouthpiece 22 as in the previous embodiments.

The cylindrical portion 21 additionally comprises an extended rear balancing segment 80 which is preferably formed as a separate component and clipped onto the cylindrical portion 21. The balancing segment 80 has a curved outer surface 81, as shown in Figure 5a.

A plurality of ribs or other protrusions 82 are located on the curved surface 81, which protrusions 82 are orientated substantially perpendicularly to the axis of curved surface 81. Markings 29 are arranged along housing 20 in line with the protrusions 82.

In order to determine the quantity of product in the pressurised dispensing container 10 the user places the housing 20 with the pressurised dispensing container 10 located therein on a flat stable surface.

The housing 20 rocks on the curved surface 81 by pivoting about successive protrusions 82 which act as successive fulcra. The housing 20 continues to rock until an equilibrium point is reached. The quantity of product remaining can be read by determining which of the markings 29 is nearest the protrusion 82 on which the housing 20 is resting.

Figure 5b shows a second version of the fifth embodiment in which a separate holder 90 is provided having a curved surface 91. Protrusions 92, similar to those of the first version, are provided on the curved surface 91. One end 93 of the holder 90 has an opening 94 shaped to receive the pressurised dispensing container 10. Markings 29 are arranged along holder 90 in line with protrusions 92.

In order to determine the quantity of product in the pressurised dispensing container 10, the user removes the container 10 from housing 20 and inserts it into the opening 94 of the holder 90 with its valve stem 11 uppermost. The holder 90 is allowed to rock on successive fulcra on curved surface 91 until an equilibrium point is reached. The quantity of product remaining is then ready by determining which of the markings 29 is nearest the protrusion 92 in which the holder 90 is resting.

Claims

I CLAIMS:1. Apparatus for determining the quantity of product contained in a pressurised dispensing container, said apparatus comprising a housing for receiving a pressurised dispensing container, at least one fulcrum about which the housing is pivotable and means for enabling the relative position of the housing to the at least one fulcrum to be adjusted, wherein the quantity of product in a pressurised dispensing container is determinable from the relative position of the housing to the at least one fulcrum when the clockwise rotating moment acting on the housing with a pressurised dispensing container located therein equals the anti-clockwise rotating moment such that the housing is balanced on the at least one fulcrum.
2. Apparatus as claimed in claim 1 wherein the housing is provided with markings, the quantity of product contained in the pressurised dispensing container being determinable from the relative position of the markings and the at least one fulcrum.
3. Apparatus as claimed in claim 1 or claim 2, wherein the at least one fulcrum is movable relative to the housing along a longitudinal axis thereof.
4. Apparatus as claimed in any preceding claim in which the at least one fulcrum is provided by a member pivotally attached to the housing.
5. Apparatus as claimed in any one of claims 1 to 3, wherein the at least one fulcrum is provided by a member removably attachable to the housing.
6. Apparatus as claimed in claim 5, wherein the means for enabling the relative position of the housing to the at least one fulcrum to be adjusted are provided by teeth on an external surface of the pressurised dispensing container receiving portion, said teeth having valleys therebetween, wherein a rim of the mouthpiece cover is locatable in said valleys.
7. Apparatus as claimed in any of claims 1 to 5, wherein the at least one fulcrum is slidable along at least a length of the housing to provide the means for enabling the relative position of the housing to the at least one fulcrum to be adjusted.
8. Apparatus as claimed in claim 7, wherein the housing further comprises a fixed support member located towards an end of the housing, said at least one fulcrum being slidable towards and away from the support member.
9. Apparatus as claimed in claim 7 or claim 8, wherein the at least one fulcrum is provided by an attachment which is formed separately from the housing and is fixed thereto by means of co-operating formations.
10. Apparatus as claimed in claim 9 as dependant on claim 8 in which the fixed support member is located on the attachment.
11. Apparatus as claimed in claim 9 or claim 10, wherein the attachment is transparent, and is located over markings on the housing relating to quantities of product.
12. Apparatus as claimed in claim 4 or claim 5, wherein the housing is provided with longitudinal slots and the fulcrum member comprises arms which are slidable along the slots.
13. Apparatus as claimed in claim 4 or claim 5, wherein the fulcrum member comprises two arms on which the housing may be supported by means of two laterally extending flanges, one on either side of the housing.
14. Apparatus as claimed in claim 1 or claim 2, further comprising a plurality of fulcra, wherein the means for enabling adjustment of the relative position of the housing to the fulcra comprise an arcuate member on which the plurality of fulcra are provided.
15. Apparatus as claimed in claim 14 in which the arcuate member is provided by arcuate shaping of the housing.
16. A method of determining the quantity of product contained in a pressurised dispensing container comprising the steps of locating the pressurised dispensing container in a housing, placing the housing such that it is supported on at least one fulcrum, adjusting the relative position of the housing to the at least one fulcrum until the clockwise rotating moment acting on the housing equals the anti-clockwise rotating moment such that the housing is balanced on the at least one fulcrum and determining the quantity of product in the pressurised dispensing container from the relative position of the housing to the at least one fulcrum.
17. A method as claimed in claim 16 wherein the balancing of the housing is achieved by moving it relative to the at least one fulcrum by incremental amounts.
18. A method as claimed in claim 16 wherein the balancing of the housing is achieved by sliding at least one fulcrum relative to the housing along a longitudinal axis thereof.
19. A method as claimed in claim 16 wherein the balancing of the housing is achieved by placing it on a flat surface and allowing the housing to pivot about a series of successive fulcra positioned along an arcuate surface.
20. Apparatus as substantially hereinbefore described with reference to and as shown in the accompanying drawings.
21. A method substantially as hereinbefore described with reference to and as shown in the accompanying drawings.