The invention relates to a fluid dispenser, and more specifically to a foam dispenser capable of combining air and a foamable liquid to produce foam.
Foam dispensers fall into two general categories: hand-held squeeze bottles and foam aerosols. Hand-held squeeze bottles are non-aerosol foam dispensers. When squeezed, foam is produced by the mixing of flowing streams of foamable liquid and air in a distinct mixing area. Foam is produced when these flowing streams are absorbed into a sponge-like foam producing element. The hand-held squeeze bottles typically use a different path for air reentry into the bottle than the path used for dispensing foam. These bottles have drawbacks, however, because they are designed to be handheld operated and must therefore be limited in size. Hand-held squeeze bottles also suffer from the disadvantage that the foamable liquid can leak out of the bottle if the bottle is not held upright. Another common disadvantage of the hand-held squeeze bottles is that they fail to replenish the reservoir bottle with adequate amount of air. As a result, the reservoir has a disproportionate amount of foamable liquid to air and is, therefore, unable to produce suitable foam.
For example, U.S. Pat. No. 5,033,654 to Bennett discloses a foam dispenser having a deformable reservoir of foamable liquid and air and a foam producing segment that includes a foam filter. When the foam dispenser is operated, air from the inside of the reservoir mixes with the foamable liquid to produce foam. To replenish air back into the reservoir after foam has been dispensed, a check valve in the form of a moving ball within a cylinder is used. The check valve is disposed outside the foam's flow path. The patent discloses that when the deformable reservoir is squeezed, the walls of the reservoir bottle collapse causing air in the reservoir to push the ball against one end of the cylindrical thereby obstructing the passage of air from the check valve. Immediately after dispensing foam, during the so-called relaxation stage, the elastic walls of the reservoir bottle revert back to their original shape and create a relative vacuum. The back pressure causes the ball of the check valve to drop from one end of the cylindrical housing to the other end allowing ambient air to replenish the reservoir. Because the plastic container used as the reservoir is relatively weak, it can only offer modest restorative forces. For example, a typical container may be able to create as little as 0.5 psi of vacuum as it returns to its original shape. In addition, once the ball is seated against the end of the cylindrical housing, the air path into the reservoir is at least partially obstructed. As a result, this and similar designs fail to timely and adequately replenish the reservoir with air. The relatively slow re-fill, or replenishment of air, fails to return the bottle to its original size. Consequently, most of its volume may consist of liquid. The next squeeze produces improper air/fluid ratio thus degrading the quality of foam, and in worst cases, only liquid (thus no foam). In the absence of an adequate amount of air in the reservoir foam production will be hampered.
Another important requirement of the air refill method is the effectiveness during the dispensing stroke. If during dispensing stroke air escapes from the refill passage, then less foam would be produced and dispensed.
Aerosol foam dispensers overcome only some of the problems of hand-held squeeze bottles. In foam aerosols, pressurized hydrocarbon gases, and in the past fluorocarbon gases as well, drive the active substances out of a reservoir. Aerosols, however, have other drawbacks. Fluorocarbons have been rejected for environmental reasons and hydrocarbons are unsafe due to inflammability. Safe propellants aimed at remedying these concerns include compressible gases such as nitrogen or compressed air. These safe propellants, however, are not as dissolvable in liquid active substances as hydrocarbons. This makes it difficult with these safer propellants to keep the pressure sufficiently high and maintain effective spraying as the active substances are consumed. Moreover, it is difficult with such propellants to obtain useful aerosol foams from conventional valve and dispenser head combinations.
Thus, there is a need for foam dispenser that can provide timely and effective air refill while providing a hermetic seal during storage and transport.
These and other disadvantages are addressed by the various embodiments of the present invention. In one embodiment, the dispensing apparatus includes a reservoir for containing air and a foamable liquid, a housing coupled with the reservoir, and a chamber moveably disposed within the housing. The chamber can move within the housing from a first position to a second position in response to the pressure difference between the reservoir's internal pressure and the ambient pressure. When in the first position, the chamber and the housing form a first inlet for communicating air between the atmosphere and the reservoir. In the second position, the chamber and the housing seal the first inlet and form a second inlet that allows the chamber to receive air and foamable liquid from the reservoir. Packing material or filters can be placed inside the chamber to provide sufficient surface area to mix the air and the foamable liquid.
The invention also provides a method for mixing at least two fluids. In one embodiment, the invention provides a method for producing foam by displacing a quantity of air and foamable liquid from the reservoir into the chamber, mixing air with foamable liquid inside the chamber to produce foam, and dispensing the foam from the chamber.
The foam dispenser of the invention is advantageous over the conventional foam dispensers because it is able to fully and timely replenish the reservoir's air supply after air has been dispensed along with foam.
The various features of the invention will best be appreciated by simultaneous reference to the description that follows and the accompanying drawings, wherein like numerals indicate like elements, and in which:
It should be noted that while the invention is discussed in reference to
In an embodiment of the invention, closure 101 can be integrated with housing 104 as one piece. In another embodiment, housing 104 and closure 101 can be two detached components that can be assembled together as one piece, for example, by providing complementary threads on each piece. This embodiment is particularly advantageous as it can easily be fitted to different bottle-necks.
Slidably contained within housing 104 is a chamber 107. Chamber 107 has a cylindrical side wall 41, an open outer end 43 (108) and a bottom 45. Bottom 45 has an axially inwardly projecting cylindrical member 47 which is hollow and has a beveled surface 49 at its inner end. Surface 49 seats against the inner surface of frustro-conical portion 33 to form an inlet valve for housing 104. In the position shown, with inlet valve 111 closed, the bottom 45 of chamber 107 is spaced from bottom 31 of housing 104. An opening 110 is formed in bottom 45.
A stopper 103 of generally annular shape is press-fit onto the outer open end of chamber 107. The outside of its outer end includes a tapered portion 51. The inside of cylindrical side wall 29 at its axial inner end also includes a tapered portion 53. As will be described in more detail below, these surfaces form an air inlet valve 113 (or air-flow path) from outside to reservoir 10, when the apparatus is in the position shown. As will be discussed below, the inlet valve 113 closes by axial outward movement of chamber 107 when the apparatus is pressurized to dispense foam.
Chamber 107 receives a filter element (not shown) in area 109. Filter element provides the necessary surface area for combining foamable liquid and air which enter chamber 107 through inlet opening 110. The filter element can include gauze or other similar material adapted to provided the required surface area for mixing foamable liquid and air. At column 3, lines 10-22, U.S. Pat. No. 3,937,364 to Wright which is incorporated herein by reference for background information, discloses various porous material suitable for providing tortuous paths for intimate mixing of foamable liquid and air. Exemplary non-compressible porous material include foraminous volcanic glass material, sintered glass material or non-compressible plastic such as porous polyethylene, polypropylene, nylon and rayon. In addition, two mesh screens (not shown) can be placed at both ends of chamber 107. The screen meshes impede the flow through the chamber 109 and create a relatively large pressure drop across the two ends of the chamber. This pressure drop causes chamber 107 to slide within housing 104. This is a significant event in contrast with the prior art as it causes chamber 107 to slide within housing 104.
Inlet opening 110 in bottom 31 of chamber 107 is open to the space between bottom 31 of chamber 107 and bottom 45 of housing 104 and is the point where foamable liquid and air enter the chamber from dip tube 106 and reservoir 10.
A cap 20 surrounds the axial outer end of housing 104. The cylindrical part 19 of housing 104 receives an inwardly extending annular portion 22 of cap 20. Annular portion 22 is fitted over cylindrical part 19 for sliding axially thereon. Cap 20 also has formed thereon a recessed portion 24 and connecting side walls 25 that define a flow path for foam exiting mixing area 109. Cap 20 also includes nozzle 112 extending therefrom and in communication with the space above chamber 107. The axial inner end of cap 20 is cylindrical and surrounds the axial outer end of closure 101 and is supported thereon for axial sliding motion. It is retained in place by the cooperation of an annual radially inwardly projecting flange on the cylindrical inner end and an outwardly projecting flange at the axial outer end of the cylindrical part of the closure 101. Cap 20 includes a stopper 18 that engages the inner surface of cylindrical part 19 of closure 101 at its axial outer end, as cap is pushed axially inward. Cap 20 can be linked optionally with either the housing 104 or the closure 101. Cap 20 can also be closed by sliding down against closure 101. Optionally, cap 20 and housing 101 can be have complementary threads thereby enabling closure of the cap with a screw action.
When the bottle is released, collapsible walls of bottle 11 return to their original shape to create a relative vacuum inside the bottle as compared to the ambient pressure. In the case where the reservoir is made from plastic, the plastic can have enough molded-in memory to create a force sufficient to replenish reservoir 10 quickly. The low pressure within the bottle draws the chamber 107 back into position shown in FIG. 1. Once chamber 107 slides back to the
It should be noted that the present invention is particularly advantageous over the conventional foam dispensers discussed above, among other reasons, for its ability to quickly and completely replenish the air in the reservoir. As briefly discussed in the Background section, the conventional hand-held squeeze bottles fail to properly replenish the air inside the reservoir. This causes the subsequent operations to have incomplete air/foam ratio. As a result, the foam quality degrades with subsequent operations. The present invention overcomes this deficiency by providing a relatively large and unobstructed air-flow path that can replenish or vent the reservoir bottle quickly and completely to preserve foam quality even after many applications.
Foam quality can be adjusted by changing the stoichiometric ratio of air and foamable liquid. For example, a so-called thick foam can have a higher amount of foamable liquid than air. The foam dispenser of the present invention can be adapted to produce different grades of foam by sizing the liquid channel cross section (for liquid flow control) and the gap between the chamber assembly and the housing (for air flow control). Thus, the size of the air flow-path or the air inlet valve can be adjusted to affect the foam quality. In other words, the path of air into the bottle reservoir 113 can be sized relatively larger (thereby displace a larger volume of air in a unit time) than each of paths 301 and 110.
Pushing down on cap 20 causes annular portion 22 to slide down cylindrical part 19 of hollow cylinder 11 and closes air inlet/foam outlet defined by connecting walls 25 and distal end 27. In one embodiment, cap 20 can be opened from a closed position by squeezing the foam bottle due to surge of foam from surface 108.
Chamber 107 receives a filter element (not shown) in area 109. Filter element provides the necessary surface area for combining foamable liquid and air which enter chamber 107 through inlet opening 110. The filter element can include gauze or other similar material adapted to provided the required surface area for mixing foamable liquid and air. At column 3, lines 10-22, U.S. Pat. No. 3,937,364 to Wright which is incorporated herein by reference for background information, discloses various porous material suitable for providing tortuous paths for intimate mixing of foamable liquid and air. Exemplary non-compressible porous material include foraminous volcanic glass material, sintered glass material or non-compressible plastic such as porous polyethylene, polypropylene, nylon and rayon. In addition, two mesh screens 140 can be placed at both ends of chamber 107. The screen meshes impede the flow through the chamber 107 and create a relatively large pressure drop across the two ends of the chamber. This pressure drop causes chamber 107 to slide within housing 104. This is a significant event in contrast with the prior art as it causes chamber 107 to slide within housing 104.
A cap 20 surrounds the axial outer end of housing 104. The cylindrical part 19 of housing 104 receives an inwardly extending annular portion 22 of cap 20. Annular portion 22 is fitted over cylindrical part 19 for sliding axially thereon. Cap 20 also has formed thereon a recessed portion 24 and connecting side waIls 25 that define a flow path for foam exiting mixing area 109. Cap 20 also includes nozzle 112 extending therefrom and in communication with the space above chamber 107. The axial inner end of cap 20 is cylindrical and surrounds the axial outer end of closure 101 and is supported thereon for axial sliding motion. It is retained in place by the cooperation of an annual radially inwardly projecting flange on the cylindrical inner end and an outwardly projecting flange at the axial outer end of the cylindrical part of the closure 101. Cap 20 includes a stopper 28 that engages the inner surface of cylindrical part 19 of closure 101 at its axial outer end, as cap is pushed axially inward. Cap 20 can be linked optionally with either the housing 104 or the closure 101. Cap 20 can also be closed by sliding down against closure 101. Optionally, cap 20 and housing 101 can be have complementary threads thereby enabling closure of the cap with a screw action.
In the embodiment of
The reservoir can be constructed from conventional re-formable and flexible plastics. Similarly, chamber 107 and housing 104 can be made of suitable plastic or non-plastic material. In the embodiments of
While not shown in the exemplary embodiments, the foam dispensing apparatus of the invention can be used with reservoirs other than a squeeze bottle. That is, although shown in an embodiment where pressure is generated by a squeezing a bottle, the disclosed arrangement may also be used with other embodiments were different sources of pressure are used. For example, a small hand-pump or a bellow can be coupled to the bottle to provide the desired internal pressure. Thus, it will be understood by one of ordinary skill in the art that such modification to the exemplary embodiments disclosed herein will not deviate from the inventive concept and will be considered within the scope of the claimed invention.
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20040060945 A1 | Apr 2004 | US |