Foam producing apparatus and method

Abstract

A foam dispenser includes a dispensing outlet, a pre-mixing chamber receiving liquid from a liquid source and air from an air source, a mixing chamber downstream of the pre-mixing chamber and proximate the dispenser outlet, and a first conduit coupling the pre-mixing chamber to the mixing chamber.

Claims

1. A hand soap foam dispenser comprising: a dispensing outlet for dispensing foam to a person's hand; a pre-mixing chamber for receiving liquid from a liquid source and air from an air source; at least one pump for simultaneously pumping liquid from the liquid source and air from the air source to the pre-mixing chamber; a mixing chamber downstream of the pre-mixing chamber; and a first conduit coupling the pre-mixing chamber to the mixing chamber, wherein foam leaving the mixing chamber travels a distance two inches or less to the dispensing outlet.

2. The dispenser as recited in claim 1, wherein the foam leaving the mixing chamber travels a distance one inch or less to the dispensing outlet.

3. The dispenser as recited in claim 2, wherein each of said pre-mixing chamber and mixing chamber comprises at least one screen.

4. The dispenser as recited in claim 3, wherein the pre-mixing chamber comprises a single 100 mesh size screen.

5. The dispenser as recited in claim 4, wherein the mixing chamber comprises a 200 mesh size screen and a 300 mesh size screen.

6. The dispenser as recited in claim 5, wherein the two screens in the mixing chamber are spaced apart by a distance not greater than inch.

7. The dispenser as recited in claim 6, wherein the 300 mesh size screen is downstream of the 200 mesh size screen.

8. The dispenser as recited in claim 3, wherein the mixing chamber comprises a 200 mesh size screen and a 300 mesh size screen.

9. The dispenser as recited in claim 2, further comprising a second mixing chamber downstream of the pre-mixing chamber and upstream of the mixing chamber.

10. The dispenser as recited in claim 2, wherein the air source is ambient air.

11. The dispenser as recited in claim 2, wherein the first conduit has a length of at least six inches.

12. The dispenser of claim 2, wherein said at least one pump comprises two pumps, a first pump for pumping said liquid soap and a second pump for pumping said air.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematically depicted view of a foam dispenser mounted on a counter.

(2) FIG. 2 is a schematically depicted prior art foam dispenser.

(3) FIG. 3 is a schematically depicted exemplary embodiment foam dispenser of the present invention.

(4) FIG. 4 is another schematically depicted exemplary embodiment foam dispenser of the present invention.

DETAILED DESCRIPTION

(5) To overcome the problems of the prior art foam dispensers, applicants have invented a foam dispenser which utilizes two or more mixing chambers. FIG. 3 discloses an exemplary embodiment foam dispenser of the present invention. For convenience, the same reference numerals are used to denote the same components in the foam dispenser shown in FIG. 3, as the foam dispenser of the prior art disclosed in FIG. 2. With the exemplary embodiment, a first mixing chamber 51 (also referred to herein as a premixing chamber) is provided to receive the liquid soap from the liquid soap reservoir or liquid source 28 and air from the air source 30. The air source may be the ambient air. A second mixing chamber 53 is provided downstream from the first mixing chamber proximate the dispenser outlet 18. Each of the mixing chambers may include one or more mixing screens 34. In the exemplary embodiment shown in FIG. 3, each mixing chamber includes two screens 34. In another exemplary embodiment, the first mixing chamber has one screen and the second mixing chamber has two screens. In another exemplary embodiment, the first mixing chamber has a single 100 mesh size screen, while the second chamber has a 200 mesh size and a 300 mesh size screen. In one exemplary embodiment, the 200 mesh size screen is about inch away from the 300 mesh size screen. In a further exemplary embodiment, the 200 mesh size screen is about inch away from the 300 mesh size screen. In another exemplary embodiment, the 300 mesh size screen is downstream from the 200 mesh size screen. In a further exemplary embodiment, the first mixing chamber has a single relatively coarse screen, while the second chamber has a relatively medium coarseness screen and a relatively fine coarseness screen. In one exemplary embodiment, the 200 mesh size screen or the medium coarseness screen is about inch, and in another embodiment about inch, away from the 300 mesh size screen or the fine coarseness screen. In another exemplary embodiment, the 300 mesh size screen or the fine coarseness screen is downstream from the 200 mesh size screen or the medium coarseness screen. However, one, or more than two, screens may be incorporated in both or either one of the mixing chambers. If more than one screen is used, applicants have discovered that they can improve on the quality of the foam by keeping the proximity or the distance 36 between adjacent screens to 1 inch or less, inch or less, or even inch or less.

(6) In the exemplary embodiment shown in FIG. 3, once the sensor 22 senses the existence of a target in its field of activation as for example, the user's hands, it sends a signal to the processor 24 which in turns sends a signal to operate the pumps 26 and 27 for pumping liquid soap and air from the sources 28 and 30, respectively, through conduits 29 and 31, respectively, to the first mixing chamber 51. An one-way valve 75, 77 may be provided along each of the conduits 29, 31, respectively, to prevent backward flow from the first mixing chamber 51 through the conduits 29, 31. At the first mixing chamber, the liquid soap and air are pre-mixed to form a air-liquid mixture 50 which moves through conduit 41 to the second mixing chamber. This air-liquid mixture is not in an optimal quality foam state. The air-liquid mixture then enters to the second mixing chamber 53 where it is converted into an optimal quality foam and is dispensed through outlet 18 on the dispenser. Optimal quality foam as used herein means a foam that has a homogenous mixture free from noticeable air bubbles and without having a liquid like texture. An optimal quality foam will remain on the surface of a person's hand and not run down when the person's palm is at an angle. It remains on the surface of the person's palm even when the person's hand is turned upside down. The first mixing chamber 51 can be placed at any distance from the liquid and air pumps or sources. In an exemplary embodiment, the conduit 29 has a length from the outlet of the liquid source to the inlet of the first mixing chamber of about a foot and the conduit 31 has a distance from the outlet of the air source to the inlet of the first mixing chamber of about a foot. In an exemplary embodiment, the second mixing chamber 53 is placed within two inches from the dispenser outlet 18. In other words the length of a conduit 55 from the second mixing chamber outlet 55 to the dispenser outlet 18 is two inches or less. In one exemplary embodiment, such length of the conduit 57 is one inch or less. The length of the dispensing conduit 41 between the outlet 52 of the first mixing chamber and the inlet 54 of the second mixing chamber, in an exemplary embodiment, is more than one foot. In another exemplary embodiment, it is more than six inches. In yet another exemplary embodiment, it is at least two feet, and in another exemplary embodiment, it is at least three feet.

(7) The first mixing chamber is used to create a consistent mixture of liquid and air which is then fed to the second mixing chamber for being converted to an optimal quality of foam. In this regard, the dispensing system of the present invention is not limited to any specific type of liquid soap as the liquid soap is pre-mixed with air to form an air-liquid mixture which is not in a complete foam state. It is this air-liquid mixture that is then converted to the optimal quality of foam as it passes through the second mixing chamber. Moreover, because the second mixing chamber is located immediately adjacent to the outlet 18 of the dispenser, the quality of the foam is more consistent, since it is just created and does not reside in any tubing, nor does it have to travel significant distances, prior to dispensing. However, it may be that when a period of time, as for example five minutes or greater between subsequent dispensing operations, occurs, the air-liquid mixture 50 within conduit 41 may change in consistency and may result in a lesser quality foam. Thus, the controller 24 may, in an exemplary embodiment, be programmed such that if after a pre-determined period of time of non-use, as for example five minutes, the first time that it dispenses foam after such non-use, the dispensing time is increased so as to ensure that all the air-liquid that resided in the conduit 41, and possible some of a freshly generated air-liquid, is converted foam by the second mixing chamber and dispensed during such dispensing cycle.

(8) In another exemplary embodiment, a third mixing chamber 70 may be provided between the first and second mixing chambers 51, 53, as for example shown in FIG. 4. The third mixing chamber may have one or more mixing screens, and preferably two or more mixing screens. In other words, in another exemplary embodiment, three or more mixing chambers may be used. Applicant has discovered that it can obtain an optimal quality of foam consistently by using two mixing chamber, a pre-mixing chamber such as the first mixing chamber 51 having a single 100 mesh size screen, and second mixing chamber such as mixing chamber 53 located within two inches (and in an exemplary embodiment, within one inch) from the dispenser outlet and having a 300 mesh size screen about inch, or to inch downstream from a 200 mesh size screen.

(9) This invention has been described for illustration purposes for use with a hands-free dispenser which uses a sensor to sense a target, such as a person's hands, such as an infrared sensor. However, the same system may be used in to a manually operated dispenser, where the dispenser spout 10 may be pushed to create a pumping action for pumping liquid as well as air which in such case would be sucked by the pumping action. In another exemplary embodiment, the dispenser may be electro-mechanical, as for example the user presses the dispenser spout 10 or a switch which in turn sends an electrical signal to the pumps to operate the pumps for pumping the liquid soap and the air.

(10) As can be seen with the exemplary embodiment, a more consistent type of foam is obtained, unlike the prior art dispensers which are not robust and which may be full of large air bubbles and/or include high liquid content.

(11) With the exemplary embodiment foam dispensers of the present invention applicants have discovered that they can obtain a consistent good quality foam independent of the distance between the dispenser outlet and the liquid soap source and/or the air source.

(12) Although the present invention has been described and illustrated in respect to exemplary embodiments, it is to be understood that it is not to be so limited, since changes and modifications may be made therein which are within the full intended scope of this application.