Metering valve for aerosols

Abstract: A metering valve to be fitted to an aerosol container comprises a dispensing member (6) in the form of a tube and a metering member (2) in the form of a cylindrical cup which receives the inner end of the tube (6). The dispensing tube (6) is slidable in an opening in a valve housing (11). A bellow (1) extends between the inner end of the dispensing tube (6) and the housing (11) to seal against escape between the dispensing tube (6) and the opening in the valve housing (11). The bellows (1) is integral with the dispensing tube (6). The inner end of the dispensing tube (6)/bellows (1) seals against a seat (9) in the floor of the metering cup (2). The upper end of the metering cup (2) seals against a gasket (3) which lies against the upper end of the bellows (1).

Description: This invention relates to a metering valve for aerosols according to the preamble of claim 1. Valves are known which are affixed to aerosol cans and are designed to release one measured dose of product/propellant mixture per actuation. These valves are typically used with medicinal aerosols, such as Metered Dose Inhalers for treating asthma and other conditions, where the product is a powdered drug suspended in a liquid propellant. US-A-2835417 describes a metered dosage valve for a container of fluid under pressure. The valve has a tubular measuring chamber having a resilient sealing gasket at one end with a central opening through which a hollow valve stem extends into the measuring chamber. The stem is depressable to close a normally open discharge passage from the measuring chamber and then supply fluid to the measuring chamber. When the valve stem is moved downwardly from its normal position, the centre portion of the gasket is bent downwardly so that when the downward force on the stem is released, the resilient gasket acts to urge the valve stem upwardly to its initial position. There is a present need for a design of metering valve which does not employ any sliding sealing faces because some products or powders can migrate past this type of seal and cause leakage or incorrect dosage. According to the invention this object is solved by the features defined in the characterising portion of claim 1. Further preferred embodiments of the invention are defined in the dependent claims 2 to 19. A preferred form of the invention will be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a cross section through a valve in accordance with the invention before being fitted to an aerosol container; Fig. 2 is a cross-sectional view of the valve of Fig. 1 fitted to an aerosol container and showing a filling nozzle applied to the outer end of the dispensing stem; Fig. 3 is a view similar to Fig. 2, showing the positions of the valve members during filling; Fig. 4 is a cross-sectional view of the top of the filled container in inverted position prior to dispensing; and Figs. 5 to 7 are views similar to Fig. 4, illustrating successive stages of the dispensing process. Referring to Fig. 1, a valve housing 7 provided with at least one port 20 in the upper part of its wall, contains a metering chamber 2 of a size dependent upon the dose to be dispensed. The chamber is normally urged by a spring 4 into a closed position in which its open upper end, provided with one or more sealing rings, makes sealing engagement with the lower face of a gasket 3 to isolate the interior of the chamber from the interior of the housing 7. The chamber 2 contains a seat 9, which may be made of a compatible elastic material such as synthetic rubber, for sealing engagement with the lower end of a dispensing stem 6 when the latter is moved into its closed position to isolate the interior of the stem from the interior of the chamber. The stem 6, which may contain a constriction 19 to assist atomization of the aerosol mixture, is centralised and supported for linear movement relative to the chamber 2 by a guide 5 which may be extended, as shown, to limit return travel of the stem. The inner end of the stem 6 is secured to or formed integrally with one end of a bellows 1 or other flexible membrane which may have a helical, thread-like form to facilitate moulding from plastics. The other end of the bellows 1 bears against a shoulder formed on the guide 5 and is provided with an external flange which is clamped between the top of the housing 7 and the gasket 3 by a ferrule 11 which may be made of an aluminium alloy and also serves to secure the guide 5 and a sealing ring 8 for engagement with the mouth of an aerosol container when the ferrule is secured to the container by crimping, as shown in Fig. 2. The container may be pre-filled before fitting the valve or filled with the valve in position using a pressure filling machine in the manner illustrated in Figs. 2 and 3. Referring to Fig. 2, the nozzle of the filling machine is applied to the outer end of the stem 6 which moves downward into sealing engagement with the seat 9. The supply of mixture under pressure through the stem 6 acts on the lower end of the chamber 2 which moves downward into its open position to permit the mixture to pass from the stem 6 through the chamber 2 and into the container through the port 20, as illustrated by the arrows 21 and 22 in Fig. 3. When the container has been filled the valve members return to the positions shown in Fig. 1 and Fig. 4, the latter showing the container inverted prior to dispensing a metered dose of its contents. For dispensing, an actuator (not shown) is affixed to the outer portion of the stem 6 and the latter is moved upward in the direction of the arrow 12 in Fig. 5 to bring the base of the stem into sealing engagement with the seat 9 to isolate the metering chamber from atmosphere as indicated at 13 in Fig. 5. Further movement of the stem 6 in the direction of the arrow 14 in Fig. 6, moves the open end of the chamber 2 away from the gasket 3 to allow the aerosol mixture in the container to fill the chamber as indicated at 15 in Fig. 6. The valve is then primed ready for dispensing, and by moving the stem 6 in the opposite direction, as indicated by the arrow 16 in Fig. 7, the contents of the chamber 2 are expelled through the stem, as indicated by the arrows 18 in Fig. 7, and when the actuator is released the stem is returned to its original position by the bellows 1 and the spring 4. Instead of the stem 6 passing through the centre of the bellows 1, the latter may be inverted and the stem affixed to its upper end. The valve housing 7 is also capable of acting as a dip cup when the aerosol container is required to be emptied in an inverted position.

Claims: A metering valve to be fitted to an aerosol container for dispensing a product, said valve comprising a housing (7), a metering chamber (2) located within said housing and a hollow actuator stem (6) extending into the chamber (2) and axially slidable relative thereto, the metering chamber and actuator stem being moveable into and out of positive sealing contact with oppositely facing valve seats (3, 9) provided on the valve housing (7) and the metering chamber (2) respectively, and sealing means being provided between the actuator stem and the housing and fixed to the housing such that relative movement between the stem and housing is permitted, characterised in that the sealing means consists of a flexible web or membrane (1) fixed to the actuator stem (6). A metering valve according to claim 1, characterised in that said metering chamber (2) is formed at its open end for sealing engagement with the valve seat (3) on said housing (11) and provided at its closed end with the valve seat (9) for the dispensing member (6). A metering valve as claimed in claim 1 or claim 2, characterised in that the web (1) is resilient. A metering valve as claimed in any one of the preceding claims, characterised in that the web (1) comprises a bellows. A metering valve as claimed in any one of the preceding claims, characterised in that the web (1) is integral with the dispensing member (6). A metering valve according to any one of the preceding claims characterised in that the positive sealing contact with the valve seats (3, 9) provides an outlet valve means (6, 9) for sealing an outlet in the dispensing member (6) from the metering chamber and inlet valve means (2, 3) for sealing the metering chamber from a main reservoir. A metering valve as claimed in any one of the preceding claims characterised in that the inlet valve means (2, 3) can only be opened when the outlet valve means (6, 9) is closed. A metering valve as claimed in any one of the preceding claims, characterised in that the outlet valve means (6, 9) is opened by movement of the actuator stem (6). A metering valve as claimed in any one of the preceding claims, characterised in that the inlet valve means (2, 3) is opened by movement of the actuator stem (6). A metering valve as claimed in any one of the preceding claims, wherein movement of the actuator stem (6) over a first distance closes the outlet valve means (6, 9) and further movement in the same direction over a second distance opens the inlet valve means (2, 3), linear movement in the reverse direction operating the valve means (2, 3; 6, 9) in reverse. A metering valve as claimed in any one of claims 6 to 10, characterised in that the metering chamber (2) is fast with the seat (9) of the outlet valve means (6, 9). A metering valve as claimed in any one of the preceding claims, characterised in that the metering chamber (2) defines a cylindrical cup which receives the inner end of the actuator stem (6). A metering valve as claimed in any one of claims 6 to 12, characterised in that the seat (3) of the inlet valve means is mounted on the valve housing (11). A metering valve as claimed in any of claims 10 to 13, characterised in that the actuator stem (6) is returned over the first distance by the web or membrane (1). A metering valve as claimed in claim 15, characterised in that the web or membrane (1) surrounds the inner end of the actuator stem (6). A metering valve as claimed in any one of claims 12 to 15, characterised in that the cylindrical cup also receives at least part of the web or membrane. A metering valve as claimed in any one of the preceding claims, characterised in that the web or membrane (1) at least partly defines the metering chamber (2). A metering valve as claimed in any of claims 10 to 17, characterised in that the actuator stem (6) is returned over the second distance by a second spring means (4). A metering valve according to any one of the preceding claims characterised in that a housing (11) is provided for the valve which also acts as a dip cup when an aerosol is required to be emptied in an inverted position.

Inventors: SULLIVAN HOWARD MICHAEL, SULLIVAN, HOWARD MICHAEL
Applicants: SULLIVAN HOWARD MICHAEL, SULLIVAN, HOWARD MICHAEL
Application year: 1993
Main classification: B65D83
IPC codes: B65D83