Aerosol Dispensing Device

Abstract

An aerosol dispensing cap unitarily formed from a flexible and elastic material to provide a dome shaped diaphragm, a central hub and discharge outlet tube, the dispensing outlet tube having an integral valve midstream which permits communication between the tube and volume beneath the cap in the unactuated position, the hub being ported to the tube and releasably chambered to engage and open the aerosol valve when depressed, the volume beneath the cap forming a reservoir of negative pressure when the cap is depressed, causing aerosol material in the tube, and valve stem to be drawn into the reservoir.

Description

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to the field of dispensing heads or caps for aerosols and more particularly that type of aerosols which are adapted to be dispensed in the form of foam.

The dispensing of foam forming aerosols has exhibited a serious problem of after-foaming which has plagued all aerosols in which the propellant is mixed with the contents upon discharge. After foaming results from the expansion of residual material left in the valve chamber and the exit passage of the actuator cap due to the lack of a driving medium after the valve has seated. This after-foaming results in the unsightly and unsanitary accumulation of foam which sets or dries at the exit port of the dispenser and also an accumulation in the exit passage and valve stem which may dry and clog the passage, thus hampering further operation of the aerosol device.

2. Description of the Prior Art

Foam dispensing heads of this general type and which are typical of prior art devices peculiarly subject to after-foaming problems have been described in such patents as Abplanalp U.S. Pat. Nos. 2,753,214 and Re 24,555. U.S. Pat. No. 2,753,214 is directed to a unitary foam dispensing head having a flexible diaphragm and hub which overlay the valve stem. Depression of the circular-shaped diaphragm causes the valve to unseat and discharge foam through the discharge nozzle. As noted by Abplanalp in his Reissue No. 24,555, the cap described U.S. Pat. No. 2,753,214 has inherent problems for dispensing aerosol foam or any other aerosol material in that when the diaphragm is constructed as described, it must be very elastic because of its relative small diameter for some valve stems require depression in excess of one-sixteen inch in order to open a valve. By cutting the top free about much of its periphery, the flexibility was increased according to Re. 24,555. But both arrangements suffered from after-flow and after-foaming of the aerosol material in the valve stem and cap passage when the valve is closed.

The rigidity of the caps in the prior art, due to the rather rigid discharge passage formed in the diaphragm, is overcome in this invention by a gate valve formed in the discharge passage. Since the discharge passage of this invention is continuous only in the plane of the head due to the transversing valve in the passage, resistance to flexure is minimized. Further, the prior art dispensing caps do not treat the after flow after-foaming problem or removal of residual material in the discharge passage.

In the present invention, both problems are surprisingly solved simultaneously. The aforementioned improved and increased flexibility of the diaphragm is used to provide a means for removing material not dispensed from the discharge passage, thus providing an aesthetically pleasing, non-clogging and sanitary dispensing cap. This is accomplished by unique utilization of the volume beneath the cap. The cap cooperates with the mounting cup of the valve to form a residue cache and diaphragm top. The volume of the residue cache is reduced as the diaphragm is depressed and a reservoir of negative pressure is created when the cap is released. When the discharge passage is exposed to the negative pressure, the aerosol material left in it and in the value stem is drawn into the reservoir thereby emptying and cleaning them.

SUMMARY OF THE INVENTION

The aerosol dispensing cap of the present invention, is generally dome-shaped and formed from a flexible and elastic compound such as plastic. The cap is mounted on the dispenser can valve mounting cup by means of a peripheral bead which locks beneath the outer rim of the valve mounting cup. A discharge passage and tube are integrally formed with the cap and communicate with the center hub by means of a port. The hub is positioned under the apex of the cap and contains a chamber to receive, engage and open the valve stem when the cap is depressed. In the unactivated position the hub chamber is released from the stem. In another form of cap embodying the invention the hub may be recessed to more snugly receive the valve stem and move axially with it.

Positioned in the tube is a gate type valve which exposes the tube and passage to the volume beneath the cap. As the cap diaphragm is depressed or flexed at the hub, the hub descends and unseats the valve stem; the volume beneath the cap is decreased; the gate valve closes, and the desired amount of aerosol product is discharged. When the pressure on the hub is released, the cap rises due to its natural flexibility and elasticity of the diaphram, to its dome position, thus creating a reservoir of decreased pressure beneath the cap.

As the cap rises, the dispenser valve closes, the hub chamber clears the stem and the gate valve exposes the tube and passage to the negative pressure beneath the cap. Any material in the tube down stream from the gate is drawn into the reservoir through the gate and any material upstream from the gate is drawn into the reservoir either through the gate or the hub port. Moreover, since the valve stem is also exposed to the reservoir, material left in the downstream side of the stem will tend to be drawn into the reservoir directly or through the tube.

DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, reference is made to the accompanying drawings, in which:

FIG. 1 is a perspective view of the aerosol can with the dispensing cap embodying the present invention mounted on the valve cup;

FIG. 2 is a sectional view as indicated in connection with FIG. 1 of the cap in the unactivated position;

FIG. 3 is a sectional view as indicated in connection with FIG. 1 of the cap in the activated position;

FIG. 4 is a fragmented horizontal sectional view as indicated on FIG. 2 of the tube valve in the open position (valve gate shown as dotted);

FIG. 5 is a fragmented horizontal sectional view as indicated on FIG. 3 of the tube valve in the closed position (valve gate shown as dotted); and

FIG. 6 is a fragmented horizontal sectional view of the tube valve gate as indicated in FIG. 2.

DESCRIPTION OF A PREFERRED EMBODIMENT

The aerosol dispensing cap 10 of this invention shown in the drawings is in the form of a unitary dome-shaped cap which is formed from a flexible resilient material such as rubber or plastic. The entire cap 10 may be integrally molded of the material but the principal area of flexure is the top portion, the diaphram or head 11 of the dome, which causes the decrease in the reservoir volume R beneath the cap when it is flexed axially inwardly.

The cap 10 is formed to provide a crowned head portion 11 and a circular-shaped wall 12. In the preferred embodiment, the wall section 12 is flared outwardly and provided with an internal bead 13 which is sprung over the peripheral edge of the aerosol valve mounting cup C to provide closure of the cap therewith and create a reservoir R between the cap 10 and valve cup C. It will be appreciated that the wall section may also be formed in an accordian shape to provide even greater flexing. The cap 10 is fixed in position over the cup C by means of three posts 14 integrally formed to the interior of the wall 12 at equal positions around the circumference thereof, and which prevent vertical or axial movement of the cap during actuation of the dispensing valve V by pressure on the dome 11.

A foam or other aerosol material flow tube 15 is integrally molded with the head 11 and originates from the central hub 16. Downstream, the tube 15 terminates at and forms the gate 17 for the discharge passage valve 18.

The discharge passage 19, which is enlarged as a final expansion region when the cap is used with a foam product is molded axially with the tube 15 forming the seat 23 of the passage valve 18 and extending beyond the wall 12 to form the terminal foam expansion section 19 and spout 20. The cross-section of the passage 19 is gradually reduced upstream from the wall 12 by causing the bottom portion of the passage 19 to assume a V shape at the valve 18 to form the valve seat 23. The discharge passage valve 18 of this invention is essentially of the gate type. The gate 17 is formed in part by the flow tube 15 and in part by a flap which extends from the terminus of the flow tube 15 to provide the necessary cross-sectional area to close the valve 18. The discharge channel 19 is reinforced at the wall 12 by means of a gusset 21 molded to the underneath section of the discharge channel 19 and the post 14.

The central hub 16 in the preferred embodiment is formed with a hemispherical chamber 22 which surrounds the valve stem v and seats on the valve stem v in the actuated position, as illustrated in FIG. 3. It will be appreciated that the chamber 22 may also be formed in other shapes. In the preferred form the chamber 22 does not closely surround the valve v in the unactuated position so that the aerosol material may be more efficiently drawn through the clearance and back pressure relieved. The clearance between the chamber 22 and the valve stem v and the travel in the valve provide the decrease in reservoir R volume. In the event further travel is necessary, the accordian-shaped wall embodiment may be used. The hub 16 is cored to provide a communication port between the chamber 22 and the tube 15.

As the cap 10 is depressed into the actuated position and engages the stem v, FIG. 3, the valve gate 17 moves downward and rotates slightly inwardly relative to the seat 22 resulting in closure of the valve 18. The depression of the cap 10 causes the dome diaphragm to expell air from beneath the cap 10. As the cap 10 and hub 16 return to the unactuated position due to the natural flexing of the diaphragm, and the spring forces generated in the posts 14, the pressure in the reservoir becomes negative with respect to atmospheric pressure and the gate 17 unseats from the channel valve 18. The negative pressure causes the aerosol material that has remained in the nozzle 20, tube 15 and valve stem v to be drawn into the reservoir R through the valve 18 and port 16. The clearance between the chamber 22 and valve stem v functions to permit material to be drawn from the tube through the port 16 and past the stem v most effectively and to reduce back pressure that would occur if these components were engaged.

In accordance with the present invention the cap 10 is designed to form a pressure vessel containing a reduced pressure which is utilized to withdraw aerosol material from the discharge outlet 15 and 19 and valve stem v. This withdrawal is not only useful for aesthetic reasons but also for sanitary reasons. When the contents of the container is such that it requires freshness, for example food stuff, or requires a substantially anaerobic composition for use, as in some medicinal and bacterial compounds, removal of unpropelled contents greatly increases the quality of effectivenss of the dispensed material. Maximum withdrawal of unpropelled contents is assured by the dual withdrawal ports, namely the gate valve 18 and the clearance between the valve stem v and hub chamber 22, which work in concert with the resilient diaphragm 11 to provide end and midstream material withdrawal.

The use of an engageable chamber hub and the increased apex height also serve to increase reservoir volume R and thus assures adequate reduction of the reservoir for the withdrawal function pressure. The stresses generated in the diaphragm top 11 and wall 12 fully provide for the return of the cap 10 to the unactivated position and are independent of the return action of the valve stem v.

Other features and advantages of the invention will become apparent but all are intended to be included with the scope of the claims to the invention.

Claims

What is claimed is:

1. A dispensing head for aerosol containers which is the combination of a generally dome-shaped head formed from a flexible and elastic material to create a diaphragm top, the head having an integral, flexible, peripheral wall engageable on an aerosol container valve cup and having integrally formed therewith a central hub; a discharge outlet formed by a dispensing tube originating from the hub and a discharge expansion chamber comprising a walled passage, the inner end of the passage being axially formed to the tube and the outer end of the passage extending through the head whereby the contents of the container pass directly through the passage to the exterior of the head; the hub being formed with a downward facing engageable chamber to depress and open the container valve when pressure is applied to the exterior of the head, the chamber communicating with the tube by means of a port to permit the flow of the contents out through the container valve stem and into and through the tube; a valve formed in the discharge outlet, the seat of the valve being formed by the inner end of the expansion passage and the gate of the valve formed by a flap extending from the dispensing tube; both the top and walls being of flexible and elastic material so that as the head is depressed, the valve flap closes into the seat and the air volume beneath the head is reduced, and as the head is released; the head and hub return to their unactivated position and the valve flap opens to expose the discharge expansion chamber and tube to the negative pressure beneath the cap.

2. A dispensing head of claim 1 wherein the central hub is integrally formed on the underside of the diaphragm top and in which the outer end of the passage extends through the wall of the head.

3. A dispensing head of claim 2 wherein the hub chamber is hemispherical in shape.

4. A dispensing head of claim 1 in which the hub chamber is not in contact with the valve stem in the unactuated position.

5. A dispensing head for aerosol containers having a valve stem extending from a valve cup comprising: a generally hollow cap body of flexible resilient material, said cap body including means for engaging said aerosol container valve cup, the interior of said cap body cooperating with said valve cup to form a pressure vessel, said pressure vessel containing reduced pressure when the cap is depressed; discharge outlet means located in the interior of said cap body and extending therethrough to direct the flow of product to the exterior thereof, the inner end of said outlet means being adapted to depress and open the container valve when pressure is applied to the exterior of the cap, the vessel communicating with said discharge outlet means through a valve formed therein downstream from said inner end, the valve being in a closed position when the cap is pressed into the actuating position and in the open position, whereby communication is achieved to draw undispensed product left in said discharge outlet means through the valve opening and into said vessel, when the actuating pressure on the cap is released.