Device for generating an aerosol, provided with a dosing unit

The invention relates to an aerosol container, also known as a spray can. For determined applications it is desired that the amount of aerosol exiting when the valve is operated is dosed. This finds application for instance, though not exclusively, in the administering of an aerosol against snoring. Another field of application lies in the dosing of medicines, such as remedies used against asthma.

The invention provides for this purpose a device for generating an aerosol, comprising a container for a gas under pressure, a normally closed valve which is placed in the container and which is opened during operation, operating means for operating the valve, guide parts connecting to the valve for guiding the generated aerosol outward from the valve, and a dosing vessel connected to the valve for dosing the aerosol exiting the valve.

The dosing unit is for instance formed by a dosing chamber. This chamber can be placed on the inside of the container, so upstream of the valve in the direction of movement of the aerosol, although the chamber can also be placed outside the container connecting to the valve, downstream of the valve in the direction of movement of the aerosol. In this latter case a secondary valve will have to be placed between the dosing chamber and the outside world.

According to a preferred embodiment the dosing vessel is coupled to the interior of the container by means of a movable wall element. The pressure prevailing in the container is hereby transferred to the interior of the dosing chamber, so that when the valve is opened the dosing chamber is emptied under uniform pressure, and thus at a uniform flow rate.

Although this movable wall part can be formed by a membrane, it is recommended that the movable wall element is a rigid wall element which is movable between two extreme positions. The dosage can after all hereby be determined more precisely. This is because the change in volume of the dosing chamber is then the same so that, when the pressure remains constant, the dosage is the same.

In order to refill the dosing chamber after dosing from the dosing chamber it is recommended that an opening with a small passage is arranged in a wall part of the dosing vessel for the purpose of forming a connection between the content of the dosing vessel and the interior of the container. This opening can otherwise also be formed by for instance clearance between the movable wall element and the fixed wall parts of the dosing chamber. The opening must be large enough that the dosing chamber can be filled in a reasonable time between two dosing operations, but also small enough that the leakage during dosing is not too great

A spring element is preferably arranged for urging the wall element away from the interior.

Yet another preferred embodiment provides the measure that a device for stabilizing the pressure prevailing inside the container is placed in the container. Such stabilizing devices are per se known. With such a stabilizing device the pressure is stabilized, whereby the dosing of the device according to the invention is stabilized because the dosing depends to a great extent on the pressure prevailing in the container.

Another preferred embodiment provides a method for dosing a quantity of aerosol, comprising the following steps of: causing aerosol to flow via an opening with a small % passage into a dosing chamber placed in an aerosol container; opening a valve placed between the dosing chamber and an outflow tube, whereby the aerosol present in the dosing chamber is dosed via the outflow tube, wherein, owing to the pressure prevailing in the interior of the container, the pressure is transferred via a movable wall element of the dosing chamber to the interior of the dosing chamber, and this pressure causes the expulsion of the aerosol.

The present invention will be elucidated hereinbelow with reference to the accompanying figures, in which:

Fig. 1-7 show cross-sectional views of an embodiment of the invention at various stages; and

Fig. 8 is a cross-sectional view of an alternative embodiment.

An embodiment will now be elucidated with reference to the accompanying figures. Figure 1 shows an aerosol container 1 which is provided with a cylindrical wall 2. On its top side the container is closed by a cover 3, which is provided with a central opening in which a valve 4 is placed. Valve 4 is provided with an outward extending operating tube 5 which, when it moves inward, opens the normally closed valve 4. An outflow tube 7 arranged in a head 6 placed on can 1 connects to tube 5. Outflow tube 7 extends into a spout 8 extending outside head 7. A handle 9 is further integrated into head 6. This handle 9 extends outside head 6. The handle is mounted in head 6 such that when handle 9 is pressed in the direction of arrow 10 the operating tube 5 is pressed downward and valve 4 is opened. When handle 9 is released, the handle is pressed outward again by a spring (not shown) so that valve 4 closes again.

Valve 4 comprises a substantially cylindrical housing 11 which is provided with an opening 12 on its underside. This cylindrical housing is connected to cover 3 by means of a form-fitting connection. Inside cylindrical housing 11 a closing body 13 can be í' moved in axial direction concentrically with housing 11. Guide means 14 are arranged for this purpose. Guide means 14 are connected fixedly to housing 11. Arranged between guide means 14 and closing body 13 is a helical spring 15 which urges closing body 13 to its normal position. The closing body is fixedly connected to operating tube 5. When operating tube 5 is pressed downward, closing body 13 is pressed downward^ thereby creating space between the upper wall of cylindrical housing 11, which functions as valve seat, and the closing body 13, through which space the aerosol can flow between this valve seat and closing body 13 and into a cavity 16 arranged in closing body 13. Operating tube 7 debouches in this cavity 16 so that the aerosol can flow outside through operating tube 5 and outflow tube 7. As soon as handle 9 is released, it will reoccupy its original position, and closing body 13 will move upward as a result of the action of helical spring 15 and form a seal against the upper wall of cylindrical housing 11.

The measures according to the invention are particularly associatedCwith the dosing means. These dosing means comprise a dosing vessel 22. This dosing vessel 22 is substantially cylindrical. It is provided with a wall 25 in the form of a cylinder jacket and an end wall 23. A central opening is arranged in end wall 23 and, connecting to the central opening, is arranged a wall 25 in the form of a cylinder jacket which extends in

downward direction. This wall 25 in the form of a cylinder jacket is fixed around the bottom part of cylindrical housing 11 of valve 4, for instance by a clamping connection formed by ribs. The underside of dosing vessel 22 is open. Arranged in the dosing vessel is a piston 26 which is urged downward by a helical spring 27 j which is likewise arranged in dosing vessel 22. The lowermost position of piston 26 is defined by a rib 28 extending on the inner side of the bottom edge.

Figure 1 shows the rest position of the above elucidated device. Container 2 is herein filled with a propellant and, in the application provided here, with a means for preventing snoring which is intended for application at the back of the mouth cavity, onto and in the vicinity of the uvula. In order to facilitate application, there is arranged on the spout a stop shoulder 30, which can be placed against the lips when the aerosol is administered.

In the rest position shown in figure 1, dosing chamber 22 is filled with the content of container 2 as a result of a small opening arranged in one of the walls thereof. The filling can otherwise also take place by means of leakage between piston 26 and wall

23.

The situation shown in figure 2 results when handle 9 is operated in the direction of ^. arrow 10. Operating tube 5 is herein moved downward, whereby the valve is opened. Due to the pressure prevailing in the dosing chamber, the aerosol present therein will be forced outward through operating tube 5 and outflow tube 7. Because piston 26 is movable, the pressure in the dosing chamber will be maintained by the pressure acting on the piston on the outside. The volume of dosing chamber 22 will therefore decrease, while the pressure therein 22 remains as constant as possible, which enhances reproducibility of the dosage.

Figure 3 shows the situation during emptying.

The situation shown in figure 4 results following emptying of the dosing chamber. Piston 26 has here reached the underside of the internal cylinder jacket wall 25, whereby a further decrease in volume of dosing chamber 22 is prevented. The outflow of the aerosol is therefore stopped.

As a result of this stop the user will release handle 9. The situation is then obtained as shown in figure 5. Piston 26 will then be urged downward under the action of helical spring 27. Dosing chamber 22 will herein be filled with the aerosol as a result of the presence of a leak between piston 26 and wall 23 in the form of a cylinder jacket, or through a small opening arranged in one of the walls of dosing chamber 22. Because this opening or leak must be small so as not to disrupt the dosing process, refilling of the dosing chamber will take place slowly, according to present expectations in the order of magnitude of several tens of seconds.

The situation of figure 7, which corresponds with the position of figure 1, is obtained once the filling process has ended because the piston has reached its lowermost position.

In the present application the dosage volume amounts to about 1 ml. With the associated dimensioning it is however possible to obtain dosage volumes between 0.8 ml and 1.7 ml. It will be apparent that different volumes can be obtained by modifying the dimensioning, in particular of the volume of the dosing chamber.

The time frame within which the actual dosing or administering process takes place can also be adjusted by dimensioning of the spring, the volume of the dosing chamber and the passage of the channels through which the aerosol passes as it exits.

It is otherwise possible to apply diverse variations to the shown embodiment. The dosing chamber can for instance be constructed in different manner, for instance by being manufactured integrally from flexible plastic. The resilience of the plastic serves here to obtain the force necessary after dosing to urge the dosing chamber back into its original form. A small opening, will of course have to be arranged in this plastic dosing chamber for the refilling process.

The position of the dosing chamber can also be modified; in the example elucidated above the dosing chamber is placed inside the container of the aerosol' mixture. It is however also possible to place the dosing chamber on top of the container, otherwise in combination with the measure that the valve is placed downstream of the dosing

chamber, although this will require the necessary structural modifications. In this latter configuration the valve can also be placed between the interior of the container and the dosing chamber. In order to enable good control of the dosing process, a secondary valve must then be placed between the dosing chamber and the outflow channel. A mechanism must moreover be provided for the purpose of operating the two valves such that the required operation is achieved.

Figure 8 shows an embodiment wherein a pressure compensation device 30 is present in the container for holding the pressure as constant as possible.