CA1074365A

CA1074365A - Foam device

Info

Publication number: CA1074365A
Application number: CA285,095A
Authority: CA
Inventors: Walter H. Wesner
Original assignee: AFA CORP
Current assignee: AFA CORP
Priority date: 1976-08-20
Filing date: 1977-08-19
Publication date: 1980-03-25
Also published as: CH613105A5; NL7708634A; IT1079826B; GB1572818A; SE7709265L; AU510972B2; FR2361933A1; BE857971A; DK370077A; DE2737160A1; AU2729077A; JPS5340404A; NO772835L; FR2361933B1; BR7705556A

Abstract

TITLE: FOAM DEVICE
ABSTRACT OF THE DISCLOSURE: Liquid dispensed from a trigger-type dispenser can be foamed by a foam generating element that contains a plurality of chambers and one or more screens; liquid is aerated and the foam is formed within the element. In one embodiment the element is adapted to fit over the nozzle of a trigger-type dispenser; in another embodiment the element re-places the nozzle altogether.

Description

10743~5 1. FIEED OF THE INVENTION
The invention relates to an element for use in conjunc-tion with a liquid dispenser, preferably of the trigger type or finger pump type which element causes the product to be dis-pensed in the form of a foam rather than in the form of a stream spray or mist.
Trigger-type dispensers with which the devices described herein are particularly useful are illustrated by British Patent Numbers 917,135, 1,315,866 and 1,331,842 which correspond to U.S. Patents 3,016,202, 3,685,739 and 3,650,473, respectively.

2. RELEVANT PRIOR ART
Foam-generating nozzle units adapted for use with dispensers of the trigger type are the subject of U.S. Patents 4,013,228 and 3,946,947. While these devices are effective, they are characterized in practice by a high length to diameter ratio which presents problems in terms of filling and packaging products having a rather elongate dispenser.
Thus, in accordance with the present teachings, a foam generating element is provided which comprises a body means adapted at one end to receive a liquid pump from a liquid dispenser and at the other end to dispense foamed product.
The element includes a first chamber within the body means whereby the liquid is mixed with air, a second chamber is provided adjacent the first chamber through which the aerated liquid passes, the second chamber is of substantially the same or lesser diameter than the ~irst chamber. A third chamber is provided adjacent to and of larger diameter than the second chamber and receives aerated product from the second chamber. Screening means is provided covering the downstream end of the third chamber and through which the product in the third chamher is forced and outlet means is 10743~;5 provided for dispensing the foamed product.
In accordance with a further embodiment, a foam generating device is provided which comprises a body open at one end to receive liquid pumped from a liquid dispenser at the other end to dispense foam product, including within the body:
(a) a first chamber into which the liquid is introduced and mixed with air to initiate foam generation, (b) a second chamber adjacent the first chamber through which the initially generated foam and aerated liquid passes, the second chamber being of substantially the same or lesser cross section than the first chamber and being provided with means for generating more foam of finer texture, (c) a third chamber adjacent to and of larger cross section than the second chamber and which receives aerated and foamed product from the second chamber, (d) screening means covering the downstream end of third chamber and through which the product in the third chamber is forced, and (e) outlet means for dispensing the product as a foam.
By yet a further teaching a foam generating device is provided which comprises a body open at one end to receive liquid pumped from a trigger type dispenser and at the other end to dispense foamed product, including within the body;
(a) a first chamber into which the liquid is introduced for mixing with air, ~b) one or more air passages for introducing air into the first chamber, (c) a second chamber adjacent the first chamber, through which the aerated liquid passes, the second chamber being of substantially the same cross section as the first ~ -2a-__ 1~743~;5 chamber and being provided with means for generating foam, (d) a third chamber adjacent to and of larger cross section than the second chamber and which receives aerated and foamed product from said second chamber, (e) screening means covering the downstream end of the third chamber through which the product of the third chamber is forced, and (f) outlet means for dispensing the foamed product.
DESCRIPTION OF THE DRAWINGS
Figure 1 is a longitudinal sectional view of one embodiment of the invention and Figure la is a view of this embodiment as seen from the right side.
Figure 2 is a longitudinal sectional view of the pre-ferred embodiment of this invention and Figure 2a is a view of this embodiment as seen from the right side.
DESCRIPTION OF THE INVENTION
The foam producing elements are, in the embodiment of this invention illustrated by Figures 1 and la, attached to the nozzle of a trigger-type dispenser. In another embodiment, illustrated by Figures 2 and 2a, the nozzle is eliminated as a separate piece and is formed as an integral part of the foam-producing element.
Referring to Figures 1 and la, 101 indicates an outer shell or body of cylindrical form, said body containing two screens 110 secured by two screen holders, 109. Body 101 is adapted to be secured to the nozzle of a trigger-type dispenser, generally indicated by 102, which dispenser delivers its product via orifice 102. Contained within body 101 is aspirating chamber 104 of -2b-~0743~5 generally cylindrical shape which ~buts dispenser nozzle 103 and which is provid-ed wlth aspirating slots 105. S~ots 105 cooperate with slots 106 located in the body to introduce air into liquid maving through chamber 104. It should be noted that slot 106 defined by the dotted lines in Figure 1 wculd not nDrmally appear in a sectional drawing' their presence however, helps to illustrate the oommuni-cation between inner chamber 104, aspirating slots 105 and the atmDsphere. Body lOl is also provided-with fo3m-fcDmin~icha~ber 107 of cylindrical shape, having a diameter or cross section less than chamber 104, which chamber 107 abuts an expansion chamher 108. EXpansion chamDer 108 is located between chamber 107 and screens 110' foan molding chamber 111 follows the screens. The diameter or cross section of expansion chao~Der 108 is substantially larger than that of foamrforming chamber 107, the abutting relation of chambers 107 and 108 being ; such as to provide, as shown in Figure 1, a nozzle at the inlet to the expansion - chamDer 108.
Referring to Figures 2 and 2a, 1 indicates an outer shell or body of cylindrical form, which may or may not be tapered in the manner shown. At each end, body 1 defines a generally cylindrical opening, one opening, generally indicated at 2, is adapted for attaching the foam b dy to a dispenser, thereby ; eliminatLng the separate nozzle illustrated ~y 102 in Figure 1. m e other open-ing defines chamber 8 which mDlds the fa~m and ~;rects it to its target. Chamber 8 terminates with screen 7, which is interposed ketween chamber 8 and e~pansion ch~mber 9. This chamber has a larger diametPr or crDss section than foam-forming chamker 6 which abuts, the abutting relation being such as to provide a n~zzle at the inlet bo expansion chamber 9, as shown in the drawing. Chamber 6 is generally cylindrical an~ contains one or more inberrup*er rings 4 which are constrictions formed in the wall o~ the chamber and func*ion to agitate and hLmD-genize the foam entering fm m aspirating chamber 10. Cbmmunicating between chYm~aer 6 and orifi oe 3, chamber 10 is optionally provided with one ar mDre ~ wedge-shaped aspirating ~lots 5 thr~ugh which air is drawn into aspirating cham, ~er 10 by the mavement of liquid therethrough. Chamker 10 abuts orifice 3 thr.
ough which liquld is forced by the dispenser.

The foam prodNcing elements of the invention are si~ple to fabricate and are effective in ~enerating foam. The element illustrated by Figure 1 is fakricated in five parts, bcdy 101, holders 109 and screens 110. The element illustrated by Figure 2 is fabricated in two parts, ~ody 1 and screen 7. ~1anufacture of molds for production of body members 1 and 101 is a straightforward proposition and prevents no difficulties. Similarly, insertion of holders 109 and screens 110 in the device of Figure 1 and the in-sertion of screen 7 in a device of Figure 2 are straightforward.
Screen 7 is conveniently fastened to body member 1 in any con-venient manner and, where t-he screen and body mem~er 1 are of the same material, such as polypropylene, attachment is readily done by sonic welding.
Turning to the element of Figure 1, foam is.dispensed by actuating a convenient dispenser, for example by reciprocating the trigger of a trigger-type dispenser in conventional manner.
The product exits the trigger-type dispenser, and enters the foam element via orifice 103 into aerating chamber 104 where the liquid is aerated by air ~rought in through vents 105. The motion of the liquid creates a venturi, causing preliminary foaming to take place in chamber 104. The foam moves on into foam-forming chamber 107 which has a diameter smaller than that of cham~er 104. Foam forming chamber 107 compresses the foam, providing a finer textured foam and accelerates the movement of the foamed product.
From foam forming chamber 107, the foam moves on through chamber 108 and impinges on screens 110, where the larger area facilitates movement therethrough. There should be at least one and possibly as many as three screens. The screens facilitate foaming, tending to add air and break up the liquid. At three or more screens the back pressure becomes considerable and it might take an unaccepta~ly high amount of pressure to operate the trigger-type dispenser. Where two screens are used, they should be spaced apart, at least .~31 inches (.0787 cm) to facilitate

3~ the formation of a fine textured foam. If the screens are too close, they perform li~e a single screen, while if the screens are too far apart, the flow of foam is slowed and the foam can ~egin to break down before it has passed through the device.
On passing through the screens, the foam passes through cham~er 111 where the foam is finally molded and directed to the target.

~074365 The character o the foam produced, that is, wet or dry, is primarily a function of the air to liquid ratio and is generally governed by liquid coming through orifice 103, the amount of air coming in through vent 105 and the size of aspirating chamber 104.
Where the trigger-type dispenser has an adjustable nozzle, the adjustment usually provides a stream of liquid or a spray. This adjustment is a convenient means for governing the type of foam.
Where the nozzle is set for a spray, the liquid leaving orifice 103 tends to spread or flare. The ratio of air to liquid in chamber 104 is therefore relatively high and the.resulting foam tends to be drier and creamier. Where the dispenser nozzle is set for a stream, the liquid entering the foam element via orifice 103 tends to be compressed and the ratio of air to liquid in chamber 104 is relatively lower; the foam produced tends to be wetter, having less air entrained therein. The wetter foam can generally be projected further than a dry, creamy foam.
Figure 2 presents the preferred embodiment of this invention.
The foam element illustrated by Figure 2 is fabricated in two parts, the body and the screen; its assembly is extremely simple. As previously indicated, this embodiment is intended to replace the ad~ustable nozzle of a trigger-type dispenser and is intended to be fastened to such a dispenser in place of the nozzle. Upon reciprocating the trigger of the trigger-type dispenser, liquid is forced through orifice 3 into aerating chamber 10 where it is initially aerated by air entering through vents 5. The aerated material moves into foam forming chamber 6, passing interrupter rings 4 which agitate and mix the foam. From foam forming chamber 6, the foam moves on through screen 7 into chamber 8 where it is molded and directed to the target. It is noted that between the exit of chamber 6 and screen 7 the foam passes through expansion chamber 9. This chamber is believed to capture and entrain air with each stroke of the dispenser trigger and is be]ieved to assist in providing a high quality foam. This ability of the nozzle to capture air is considered significant to the ability of this embodiment to effectively function without vents 5.

The foam elements described herein can be fabricated of any convenient thermoplastic material such as polyolefin, in-cluding polyethylene and polypropylene, acrilonitrilebutadiene styrene, polyamide, polystyrene, polyvinylchloride, polyvinyl acetate, polyvinylbutyral, and the like. For reasons of ease of fabrication and cost, polypropylene is preferred.
The screen can be of any convenient and useful material whether woven or non-woven, natural or synthetic; the particular type being selected to provide a foraminous product yielding the iO desired foam and having a reasonable service life.. The screens can be of fine mesh metal or synthetic plastic or can be formed of porous synthetic material where the pores are formed by foam-ing or other methods known to the art. The pores in the screens employed can be of any convenient size and configuration to pro-duce foam of the desired character.
In connection with the production of foam it should be notedthat the element described herein obtains air in a variety of ways. The desi~n makes use of the fact that liquid product from a trigger-type dispenser already contains some air; makes use of the backflow of air through the screen, as described above in connection with the device embodied in Figure 2 and, finally makes use of air introduced through air passages such as 5. In many cases, air vents ~ can be eliminated.
Another advantage of the element described herein is that foam is generated in a very compact apparatus. The design does not require high length to diameter ratios and it is thus possible to provide a foam generating element that is extremely compact, a feature that is particularly advantageous when consumer product applications and the consequent problems of pac~aging and shipping are considered.
Additionally, the design is not sensitive to internal spray patterns, permitting a wide viscosity range of materials to be successfully foamed. The device will foam virtually any liquid that can be dispensed in a hand-operated trigger-type dispenser and that contains a surfactant.

lQ743f~5 The overall dimensions of the foam element are not considered to be critical and can be varied to provide a suitable foam.
Dimensions of one embodiment of the element illustrated by Figure 2 are as follows: the overall length is approximately 2.5 inches (6.35 cm); with the length o~ the portion attaching to the trigger sprayer (the length to the end of outlet orifice 3) being approx-imately .6 inches (1.524 cm) and the length from the end of orifice 3 to the centerline of interrupter ring 4 being approximately .25 inches (.635 cm). The distance between centers of the interrupter rings is approximately 0.1 inch (.254 cm). The distance between the end of outlet 3 and the end of foam forming chamber 6 is approximately .41 inches (1.0414 cm) and the distance from the end of outlet orifice 3 to screen 7 is approximately .5 inches (1.27 cm). The distance from the end of outlet orifice 3 to the end of the nozzle is approximately 1.9 inches (4.826 cm).
Aerating chamber 10 and foam forming chamber 6 have a di-ameter of approximately .16 inches (.4064 cm) while the outer diameter of chamber 6 is .24 inches (.6096 cm). Rxpansion chamher 9 has an outer diameter of .32 inches (.8128 cm). Foam finishing chamber 8 has an inner diameter of .40 inches (1.016 cm).
While the foam generating element described herein has been illustrated with a trigger~type dispenser, it can be used with a finger pump tvpe dispenser as well. Further, while the foam generating element has been described in terms of a separate element that can be attached to a trigger-type dispenser, it will be appreciated that this foam generating element can be incorporated into the mold desing of a trigger-type dispenser to provide an integral foam dispenser,

Claims

?AT IS CLAIMED IS:

1. A foam generating element which comprises a body means adapted at one end to receive liquid pumped from a liquid dispenser and at the other end to dispense foamed product, including a) a first chamber within the body means wherein said liquid is mixed with air, b) a second chamber adjacent said first chamber through which said aerated liquid passes, the second chamber being of substantially the same or lesser diameter than said first chamber, c) a third chamber adjacent to and of larger diameter than the second chamber and which receives aerated product from said second chamber, d) screening means covering the downstream end of said third chamber and through which the product in the third chamber is forced, and e) outlet means for dispensing the foamed product.

2. The element of claim 1 in which the body means is adapted to be secured to the outlet nozzle of a liquid dispenser.

3. The element of claim 1 in which the body means is formed with the outlet orifice of a liquid dispenser and the body means is adapted to replace the outlet nozzle of said liquid dispenser.

4. The element of claim 1 formed as an integral part of a liquid dispenser.

5. The element of claim 1 in which said first chamber is provided with aspirating means for introducing air into said chamber.

6. The element of claim 1 in which said first chamber is provided with one or more wedge-shaped slots for introducing air into said chamber.

7. The element of claim 1 in which the second chamber is of lesser diameter than said first chamber.

8. A foam generating element which comprises a body means adapted at one end to receive liquid pumped from a liquid dispenser and at the other end to dispense foamed product, including a) a first chamber within the body means wherein said liquid is mixed with air, b) a second chamber adjacent said first chamber through which said aerated liquid passes, the second chamber being of substantially the same cross section as said first chamber, c) a third chamber adjacent to and of larger cross section than the second chamber and which receives aerated product from said second chamber, d) screening means covering the downstream end of said third chamber and through which the product in the third chamber is forced, and e) outlet means for dispensing the foamed product.

9. The element of claim 1 in which the second chamber is provided with means for agitating or mixing the aerated product of the first chamber.

10. A foam generating element which comprises a body adapted at one end to receive liquid pumped from a trigger-type dispenser and at the other end to dispense foamed product, including a) a first chamber within the body for mixing said liquid with air, b) one or more air passages for introducing air into said first air chamber, c) a second chamber adjacent said first chamber, through which the aerated liquid passes, the second chamber being of substantially the same diameter as said first chamber and being provided with means for mix-ing the foam, d) a third chamber adjacent to and of larger diameter than said second chamber and which receives aerated product from said second chamber, e) screening means covering the downstream end of said third chamber, through which the product of the third chamber is forced, and f) outlet means for dispensing the foamed product.

11. A foam generating element which comprises a body means adapted at one end to receive liquid pumped from a liquid dispenser and at the other end to dispense foamed product, including a) a first chamber within the body means wherein said liquid is mixed with air, b) a second chamber adjacent said first chamber through which said aerated liquid passes, the second chamber being of substantially the same or lesser cross section than said first chamber, c) a third chamber adjacent to and of larger cross section than the second chamber and which receives aerated product from said second chamber, d) said first, second and third chambers having a common axis, said first chamber including in a wall adjacent said one end of said body means an orifice from which said liquid is pumped in the form of a spray by said dispenser, the axis of said spray of liquid being substantially co-incident with said common axis, the cross sections of said first and second chambers transverse of said axis being substantially the same, and transverse of said axis said third chamber having a larger cross section than said second chamber, e) screening means covering the downstream end of said third chamber and through which the product in the third chamber is forced, and f) outlet means for dispensing the foam product.

12. The foam-generating element of claim 11 in which said first chamber is provided with a plurality of slots in other walls thereof, said slots being wedge-shaped and extending in a direction transverse to said common axis, the narrow edge of said slots being in the inner wall of said first chamber whereby to effect an increase in the velocity and turbulence of the air drawn through said slots into said chamber by the movement of said spray of liquid and facilitation of the mixing of said liquid and air to cause preliminary foaming in said chamber.

13. The foam-generating element of claim 1 in which said second chamber abuts said third chamber, the abutting relation being such as to provide a nozzle at the inlet through which said third chamber receives aerated product from said second chamber.

14. The foam-generating element of claim 1 in which the length to diameter ratio of said third chamber is at least one to one and is substantially no greater than two to one.