Foam dispenser having selectively pressurized container

A dispenser is provided including a dispenser housing that receives disposable refill units that are to be replaced when empty. The dispenser housing includes an air compressor and an inflation plug. The inflation plug includes a needle having an outlet and further includes a vent valve in fluid communication with the outlet. The inflation plug is fluidly associated with the air compressor such that the air compressor selectively advances air to the vent valve and to the outlet of the needle. The disposable refill includes a container having an interior with a liquid portion and air portion therein. The container further includes a plug receipt, and the inflation plug of the dispenser housing engages the plug receipt such that the outlet of the needle communicates with the interior of the container. The air compressor injects air into the interior of the container through the outlet of the needle to increase the pressure inside the container, and the vent valve of the inflation plug opens if the pressure of the container rises above a set threshold.

FIELD OF THE INVENTION

The invention herein resides in the art of dispensing systems and, more particularly, to dispensers adapted for dispensing materials in the nature of a foam. Specifically, the invention relates to a foam dispenser, in which a foamable liquid is converted into foam by the forceful combination of foamable liquid and air in a foaming head. More particularly, the invention relates to a foam dispenser having a disposable container and adapted for interconnection with a motor-driven air compressor under control of a control circuit to selectively regulate the pressurization of the container and the requisite dispensing of liquid and air to a foam generator to create the desired foam product.

BACKGROUND OF THE INVENTION

Presently in the art of dispensing liquids and gels, it has become desirable to dispense such liquids and gels in the form of a foam. Typically, the foam is generated from combining a liquid or gel material with air in a forceful way, with the combination of air and the liquid or gel then being extruded through a screen, mesh, sponge or the like to obtain a foam of substantially uniform bubbles.

The invention herein will be discussed with regard to soap foam dispensers, in which liquid soap and air are combined as described for achieving the requisite foam. However, it will be appreciated that the concepts of the invention may be extended to the generation of foam from other liquids, gels, and the like, including those of alcohol-based sanitizers. Presently, soap foam is generated in a variety of ways, most of which require the depositing of a quantity of liquid soap in one chamber, an amount of air in another chamber, and compressing the two chambers to forcefully drive liquid and air to a foam generator for the generation of the foam. Such activities require significant mechanical movement, typically employing a pair of pistons, one for liquid and one for air, to drive the separate quantities to the foam generating member. Typically, these dual chambered pumps are an integral portion of disposable containers and add significantly to the cost of such containers. Moreover, being of a mechanical nature, the pumps are not given to excessive use and are typically designed to have a useful life only slightly exceeding the number of dispensing cycles available from the container.

A system is disclosed in Published U.S. Patent Application No. 2010/0102083 having a permanent compressor that is adapted to communicate with replaceable containers to drive both a foamable liquid and air from within the container to a foam generator to form a foam product. A foam dispenser includes a housing that receives a refill unit having a container with an interior containing foamable liquid and air. An air compressor, which is a more permanent part of the dispenser housing, selectively communicates with the air in the container and is employed to inject air into the container so as to increase the pressure therein. An air tube communicates with the air within the container, while a liquid tube communicates with the liquid in the container. Each tube communicates with the container through a plug seal and extends from communication with the container to a dispensing head. Separate valves communicate with each tube such that the tubes can be shut-off so that the container can be pressurized. Once the container is pressurized to a desired dispensing pressure, the valves associated with the liquid and air tubes are opened so that a portion of the foamable liquid and a portion of air are advanced to a foam generator wherein the air and liquid are mixed to create and dispense the foam product.

A pressure sensor and a vent valve are provided as part of the refill unit and communicate with the container so that, in the event that the pressure within the container becomes too large, the vent valve can open to prevent undesired consequences. For example, in the event of a malfunction, it might be possible for the pressure generated by the compressor to burst the container. Also, in the event that the pressure in the container is allowed to become too large (i.e., greater than the desired pressure) it is possible that the air and liquid would be advanced to the foam generator at an undesirably large pressure, leading to an undesired dispensing.

Different methods are proposed for employing the foam dispenser. In one embodiment, the dispenser receives a dispensing request from an individual using the dispenser and, upon receipt of that dispensing request, generates the desired pressure, thereafter opening the valves to permit the dispensing of foam. In a separate method, the dispenser constantly works to establish the desired dispensing pressure in the container such that, when a user places their hands at the appropriate location for a dispensing request, the container is already at the desired dispensing pressure, and valves simply need to be opened to cause the dispensing of product as foam.

The present invention improves upon the invention disclosed above. In the prior invention, the refill units include air and liquid tubes that each communicate with the container through their own separate and distinct plug. Similarly, the compressor, the pressure sensor and the vent valve all separately and distinctly communicate with the contents of the container through one of the container walls. It will be generally understood in the art that these refill units, once empty of product, must be replaced, the dispenser housing being a more permanent structure that simply receives refill units when necessary to replace older units. Employing the structure proposed in the aforementioned publication presents a number of problems in that each plug, sensor and valve that communicates with the container of the refill unit presents a potential area for leakage, thus frustrating the generation of the desired pressure. Also, associating the vent valve and sensor with the container of the refill unit is undesirable inasmuch as the refill unit (and container thereof) is thrown away and replaced when empty. Throwing away the refill unit results in throwing away the vent valve and sensor and thereby increases the cost of the refill unit. As seen in the publication, the air and liquid tubes are plugged into the container at the top thereof such that the tubes are quite long and must be appropriately guided through the structures of the dispenser housing in order to communicate between the top of the container and the outlet area of the dispenser housing. Realizing these problems with the prior publication, the present invention provides a number of structural advancements.

SUMMARY OF THE INVENTION

In one or more embodiments, this invention provides a refill unit for a liquid product dispenser. The refill unit replaces an empty refill unit in the product dispenser, when necessary. The refill unit comprises a container holding a liquid product, the container including a plug receipt providing access to the interior of the container. The plug receipt is structured to receive an inflation plug so as to mate with the inflation plug in a sealed manner. The refill unit further comprises a dispensing nozzle external of the container and fluidly communicating with the liquid product. Pressurizing the container forces liquid out of the container and forces liquid out of the dispensing nozzle. The refill unit is devoid of means for venting pressure generated in the interior of the container other than by venting through the dispensing nozzle.

In one or more embodiments, this invention provides a dispenser. The dispenser includes a dispenser housing and a disposable refill unit separate and distinct from the dispenser housing, the disposable refill unit being replaced when empty. The dispenser housing includes an air compressor. The dispenser also includes an inflation needle that is fluidly associated with the air compressor such that operation of the air compressor advances air through the inflation needle and out an outlet of the inflation needle. The dispenser further includes a vent valve. The disposable refill includes a container having an interior holding a liquid product, and a plug receipt is provided in the container. The refill unit is mounted in the dispenser housing, the inflation needle of the dispenser housing communicates with the interior of the container through the plug receipt, and the vent valve fluidly communicates with the interior of the container. The air compressor communicates with the interior of the container injecting air into the interior of the container through the outlet of the needle to increase the pressure inside the container. The vent valve opens if the pressure of the container rises above a set threshold.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

A foam dispenser according to this invention is shown inFIG. 1and designated generally by the numeral10. The foam dispenser10is defined by a housing12that receives a refill unit14including a container15providing a foamable liquid that is to be dispensed as foam, the refill unit14being replaced when the container15is empty of dispensable liquid. The refill unit14further includes a foam-generator38that will be described more particularly herein. The dispenser housing12may be either a wall-mount or counter-mount type. In a wall-mount configuration, the dispenser10schematically represented inFIG. 1would have a dispenser housing12mounted to a wall, with the interior of the dispenser housing12being accessible to insert, remove and replace refill units14as necessary. Similarly, in a counter-mount configuration, the dispenser10would have a dispenser housing12mounted to (or even just resting on) a counter, with the interior of the dispenser housing12being accessible to insert, remove and replace refill units14, as necessary. Typically, the housing12will have a hinged front or cover to allow access to the interior thereof for replacement of the refill unit14, as desired. In some embodiments of particular interest, the liquid retained in the container15is either a liquid soap or sanitizing gel, both being capable of foaming. The refill unit14is a removable, disposable and replaceable unit, as that feature is readily known and understood in the art. Typically, the container15of the refill unit14is blow-molded of an appropriate plastic material. Because the container is to be pressurized, it should be formed of materials suitable to withstand the pressurization during the life of the refill unit14. The container15could be a multi-walled container or even a bag. In particular embodiments, the container is formed of polyethylene terapthalate (PET).

The refill unit14is adapted to dispense in a downward direction, such that the liquid in the container15defines a liquid portion16in a lower portion of the container and an air portion18thereabove. The liquid portion16and air portion18comprise substantially the entirety of the interior of the container15, the air and foamable liquid being in contact with each other, without the use of a separating bladder, membrane or the like. As will become apparent herein, the air portion18is selectively pressurized to create a pressure head within the container15to assist in the dispensing operation.

Received and maintained within the housing12as a more permanent portion thereof is a motor20operative to drive an air compressor22. A compressor tube24extends from the air compressor22to an inflation plug26that selectively interacts with the refill unit14received in the dispenser housing12. The compressor tube24and inflation plug26also remain a more permanent part of the dispenser housing12. By the terms “more permanent part” as used to modify the motor20, compressor22, compressor tube24and inflation plug26it is meant that these elements are intended to remain associated with the dispenser housing12and to last for a significant time, which desirably will be for the life of the dispenser housing12. Their useful time span is “more permanent” as compared to the refill units14that are intended to be removed (when empty or malfunctioning) and replaced (to provide new product for dispensing). The intent is that the motor20, compressor22, compressor tube24and inflation plug26are to last for the life of the dispenser, but they may, of course, have to be replaced due to unexpected failure or malfunction, just as with the components of any device.

In one or more embodiments, the inflation plug26includes a body27into which the tube24extends, the tube24branching to communicate with a pressure sensor28and vent valve30, both of which are part of the inflation plug26. The pressure sensor28produces a signal corresponding to the pressure head in the air portion18of the unit14, while the vent valve30is operative to vent the air chamber18to atmosphere, as desired. The tube24also branches to provide an outlet32at a piercing needle34. In other embodiments, the pressure sensor28and the vent valve30may be located elsewhere.

The needle34serves to extend through a plug receipt35in the container15so that the compressor22can inject air into the air portion18to pressurize the container15. The plug receipt35and inflation plug26can interact in any number of ways. The plug receipt35, prior to interacting with the needle34, is whole and uncompromised so that foamable liquid and air are sealed in the container15. When the needle34interacts with the plug receipt35, the plug receipt35is compromised and the needle34extends into the interior of the container15. Many options are available for the needle34and plug receipt35, for example, the plug receipt35could provide (a) a membrane to be pierced by the needle34, (b) a puncturable orifice to be punctured by the needle34, (c) or a flapper valve through which the needle34would extend. The person mounting the refill unit14to the dispenser housing12inserts the needle34of the inflation plug26through the plug receipt35so that the compressor22can inject air into the container15at the outlet32of the tube24. The plug receipt35is preferably formed of a resilient material, such as an elastomer or rubber, and preferably is sized so as to squeeze against the needle34or body27or both to thereby create a tight seal that would prevent air from leaking from the container15at the compromised puncturable wall4.

In one or more embodiments of this invention, a person may access and grasp the inflation plug and mate it with the plug receipt, though, in other embodiments, such as that disclosed with respect toFIG. 3, the dispenser housing and refill unit can be structures so that the inflation plug and plug receipt mate upon proper installation of the refill unit, without the need for the manual manipulation of the inflation plug.

A first exemplary embodiment of an inflation plug and plug receipt is shown inFIGS. 1,4and6, with the inflation plug and plug receipt shown mated together. InFIG. 9, an alternative exemplary embodiment is shown before the inflation plug is mated with the plug receipt. In this embodiment, the plug receipt35is provided as a grommet1that is sealed to (or formed as part of) the container15. The grommet1has an open end2providing access to a passage3leading to a puncturable wall4. The needle34includes a distal end37that is sharp enough to readily pierce the puncturable wall4so that the compressor22can inject air into the container15at the outlet32, which fluidly communicates with the compressor through tube24. To assist in the insertion of the needle34, the open end2can be formed with a beveled shape (as at numeral6) that would help to align and urge the needle34into the passage3. The grommet1is preferably formed of a resilient material, such as an elastomer or rubber, and preferably is sized so as to squeeze against the needle34or body27or both to thereby create a tight seal that would prevent air from leaking from the container15at the compromised puncturable wall4.

FIGS. 10 and 11provide yet another exemplary embodiment of a plug receipt. The plug receipt35shown therein is formed in a manner similar to the valves for the inflation of sports balls (e.g. soccer, rugby, American football, and basketball). A grommet1adefines a passage3ahaving a self-sealing end4a, and an inflation needle34can be forced therethrough to place an outlet32thereof at the interior of the container15. The self-sealing end4aseals against the needle34after insertion to prevent leakage. The needle34can be blunt at its distal end, as it is not puncturing a wall but is rather being forced through a resilient restriction at the self-sealing end4a. Additionally, the outlet32can be on the side of the needle34. Although not shown, the plug26providing the needle34can include a sensor and vent valve. It should be appreciated that the term “self-sealing passage” as used herein and particularly in the claims is to be interpreted in light of such valves for the inflation of sports balls. The needle, once inserted can pressurize the container. As with the embodiment ofFIG. 9, beveled surfaces and the like could be employed, as shown, to facilitate the alignment of the needle with the self-sealing passage and its insertion therethrough.

In the embodiment ofFIG. 1, the refill unit14includes a foam generator38and an air tube40and a liquid tube42fluidly communicating with the foam generator38. In this embodiment, the foam generator38is outside of the interior volume of the unit14, and the air tube40extends from one end in fluid communication with the foam generator38to an inlet end41in direct communication with the air portion18inside the volume of the container15. Similarly, the liquid tube42extends from one end in fluid communication with the foam generator38to an inlet end43in direct communication with the liquid portion16inside the volume of the container15. In this embodiment, both the air tube40and liquid tube42extend from the exterior to the interior of the container15through a sealing cap44, and extend through the sealing cap44in a fluid-tight manner so as to prevent leakage and dripping, even when the unit is under pressure. For example, the tubes could be molded to be part of the sealing cap44. They could alternatively be mounted through apertures in the cap44, using O-ring-type seals to prevent leakage.

The foam generator38includes a mixing chamber46having an homogenizing member48therein. Those skilled in the art will appreciate that the mixing chamber is substantially a confined volume in which the liquid product and air are forcefully combined to create a premixture of foamable liquid and air. This premixture is a coarse mixture of air bubbles in liquid, and it is extruded through the homogenizing member48, which is typically a screen mesh, sponge, foam block or the like, to more homogeneously disperse the air throughout the liquid and thereby create a foam product. After extrusion through the homogenizing member48, the liquid product is dispensed as foam out of the dispensing nozzle50. An aperture51is shown in housing12to schematically represent that the nozzle50communicates with the exterior of the housing12.

The foam dispenser10also includes a hand detector or proximity sensor52, which may be of any of various types understood by those skilled in the art. The proximity sensor52emits a signal upon sensing the presence of an object at the area the sensor52monitors. Typically, the sensor52senses the presence of a user's hand or hands at the proper dispensing location, particularly in embodiments wherein foamed soap or foamed sanitizer is dispensed onto a user's hand. In the present embodiment, the sensor52would monitor the area under the dispensing nozzle50and would send a signal when an object (e.g., a user's hand) is under the dispensing nozzle50.

In this embodiment, a single shut-off valve54serves to selectively open and close the air tube40and the liquid tube42. Virtually any configuration of components suitable for selectively opening and closing the air tube40and liquid tube42can be employed, as structures and methods achieving such function are numerous and well known. In one embodiment of this invention, the air tube40and the liquid tube42are, at least at their length outside of container15, made of flexible tubing, and, in such an embodiment, the shut-off valve54may consist of elements that selectively pinch close the flexible tubing of the tubes40,42. By way of example, the shut-off valve54of the embodiment ofFIG. 1could include a sealing bar55positioned on either side of both tubes40and42, with a stop plate56positioned on the other side so that the sealing bar55is moved by the control circuit60(disclose below) to press both tubes40and42against the stop plate56to close them off.

In other embodiments of a refill unit, such as that shown inFIG. 2, two shut-off valves are employed, one for the air tube40and one for the liquid tube42. In this embodiment, a valve54′ can be employed. The valve54′ includes a single stop plate56′ positioned between the air tube40and the liquid tube42so that a separate air sealing bar55′ and liquid sealing bar55″ can each separately move to press against the stop plate56and close off their respective tubes.

In yet other embodiments, such as that shown inFIGS. 12 and 13, the valve54could consist of a rotating cam600shaped such that rotating the cam600causes an extension602thereof to collapse the tubes40,42against a stop plate604. The cam600could be oval, as shown, or could have a projection or could be a circular member mounted to a shaft at an off-center position. The shape is selected so that the cam can be rotated to take up a position in which the tubes40,42are pinched closed and can be rotated to take up a position in which the tubes are open. As shown inFIGS. 14 and 15, this general concept can also be applied to the embodiment ofFIG. 2. The cam600is positioned between the tubes40,42, and rotates so that, in a first position, neither a first extension602nor a second extension606affect flow through the tubes40,42, while, in a second position, one of the extensions602or606pinches the air tube40against stop plate604, while the other of the extensions602or606pinches the liquid tube42against a stop plate608.

Referring back toFIG. 1, a control circuit60is maintained as an integral portion of the dispenser10, preferably within the dispenser housing12. The control circuit60is interconnected with the motor20to selectively activate the air compressor22. Similarly, the control circuit60interconnects with the shut-off valve54(or valves) to selectively open and close such valve or valves. The proximity sensor52is connected to the control circuit60to provide a signal when hands are present at the proper dispensing location under the dispensing nozzle50. Similarly, the pressure sensor28is interconnected with the control circuit60to provide a signal indicative of the pressure head in the air space18of the container15. Finally, in particular embodiments, the control circuit60is also interconnected with the vent valve30to allow for venting of the air portion18to atmosphere. The control circuit60would cause the vent valve30to vent to the atmosphere if the pressure in the container15builds up beyond a set maximum. In embodiments such as that shown, wherein the inflation plug26includes the pressure sensor28and the vent valve30, the inflation plug26acts as a safety device to prevent the pressure from building too high in the container15. Those skilled in the art will appreciate that the valves30and54may be of various types, while conforming to the concepts of this invention. While they may all be controlled by the control circuit60, it is contemplated that they may alternatively be self-regulating, automatically controlled as by a set cracking pressure or the like. If a vent valve with a set cracking pressure is employed, there may be no need for control circuitry to actuate the vent valve.

From a structural standpoint, the removal and replacement of a refill unit14—and the necessary interconnections to be effected at such replacement cycles—is simple and easy to undertake. In the simplest form, the refill unit14is first placed within the dispenser housing12, with the dispensing nozzle50positioned at the desired dispensing location and the tubes40,42positioned to be acted upon by the shut-off valve54. The inflation plug26, particularly the needle34, is then mated with the plug receipt35so that the compressor22can inject air into the container15. As disclosed above, the shut-off valve54acts to selectively open and close the air tube40and the liquid tube42. A more particular mounting concept is shown inFIG. 3.

Referring now toFIG. 3, a concept for achieving an appropriate mounting of a refill unit14is shown schematically. The dispenser housing12includes a shelf62that defines a channel64for receipt of the air tube40and liquid tube42. The dispenser housing12further includes a mounting plate66and guides68extending therefrom to create a pocket70for receipt of the upper portion17of the container15. The upper portion17of the container15includes the plug receipt35as a piercable member, and the inflation plug26is appropriately located in the dispenser housing12so that needle34of the inflation plug26(needle not shown inFIG. 3) pierces the plug receipt35when the upper portion17of the container15is inserted into the pocket70, the alignment of the needle34and the plug receipt35being assisted by the guides68. The upper portion17is inserted first and then pushed upwardly to cause the needle34to pierce the plug receipt35. Thereafter, the bottom portion19of the container15is pushed inwardly to rest on the shelf62and place the air tube40and the liquid tube42in the channel64. Notably, this method for mounting the refill unit can also be employed for the refill units of the embodiments ofFIGS. 2,4and6, and the application of this mounting method to those embodiments will be apparent from the above disclosure and the figures of this application. After mounting, the shut-off valve54(or54′) operates in the channel64, opening and closing the air tube40and the liquid tube42to selectively prevent and allow fluid flow therethrough.

A third embodiment of a dispenser refill unit is shown mounted to the dispenser housing12and designated by the numeral114inFIG. 4. The refill unit114is in many respects similar to refill unit14, having a container115with a foamable liquid therein defining a liquid portion116and an air portion118. The container115also includes a plug receipt135for receipt of the needle34of a inflation plug26just as in the refill unit14, but the refill unit114of this second embodiment, includes a different placement for the foam generator138(as compared to foam generator38). More particularly, the foam generator138, which, like foam generator38, includes a mixing chamber146and homogenizing member148, is provided inside of the container115, the air tube140and liquid tube142communicating therewith as with the embodiment ofFIG. 1. Notably, the foam generator138could simply include an inlet aperture to receive liquid into the mixing chamber146, instead of receiving liquid from an actual liquid tube142, which, at any rate, is shown as being very short inFIG. 4. A single dispensing tube149extends from fluid communication with the foam generator138through a sealing cap144to present a dispensing nozzle150at the exterior of the container115. The single dispensing tube149carries foam created in the foam generator138to the dispensing nozzle150to be dispensed as in the prior embodiment, and only this single tube must be pinched and released by the shut-off valve54. Virtually any configuration of components suitable for selectively opening and closing the air tube40and liquid tube42can be employed as shut-off valve54, as structures and methods achieving such function are numerous and well known. Additionally, the shut-off valve concepts disclosed herein inFIGS. 1,12and13could be employed in particular embodiments, the adaptation of those embodiments to the refill unit ofFIG. 4being readily apparent.

Referring now toFIG. 5, a third embodiment of a foam dispenser is shown and designated by the numeral210. This dispenser210includes a dispenser housing212that receives a refill unit214. In light of adaptations made to the refill unit214(as compared to refill units14and114), a slightly altered dispenser housing212is employed in this embodiment. However, because many elements are similar, like parts receive like numerals though increased by 200 as compared to the embodiment ofFIG. 1and increased by 100 as compared to the embodiment ofFIG. 4. In this embodiment, the refill unit214has been adapted to receive air from the compressor222through its air tube240rather than through a separate inflation plug member, as with inflation plug26of prior embodiments.

The refill unit214includes a container215with a foamable liquid retained therein to define a liquid portion216and an air portion218. As with prior embodiments, an air tube240extends from one end that is in fluid communication with a foam generator238to an inlet end241in direct communication with the air portion218. A liquid tube242extends from one end that is in fluid communication with the foam generator238to an inlet end243in direct communication with the liquid portion216. In this regard, the refill unit214has an air and liquid tube and foam generator structure very similar to that ofFIG. 2, and can have a very similar shut-off valve as well. Virtually any configuration of components suitable for selectively opening and closing the air tube40and liquid tube42can be employed as the shut-off valve, as structures and methods achieving such function are numerous and well known. Additionally, the shut-off valve concepts disclosed herein inFIGS. 2,14and15could be employed in particular embodiments, the adaptation of those embodiments to the refill unit ofFIG. 5being readily apparent. In particular embodiments, the dispenser housing212includes a shut-off valve254′ including a single stop plate256′ positioned between the air tube240and the liquid tube242so that a separate air sealing bar255′ and liquid sealing bar255″ can each separately move to press against the stop plate256and close off their respective tubes. In this embodiment, a port245extends off of the air tube240outside of the container215, below the sealing cap244and above the valve254′.

The compressor tube224extending from the air compressor222is sealingly mated with this port245, and a valve and pressure sensor assembly generally represented at247is associated with the compressor tube224in order to sense the pressure within the tube224and close off the same (through operation of the valve) as necessary. Thus, it will be appreciated that the compressor222can pressurize the container215, as in prior embodiments, though through the air tube240.

A control circuit260is maintained as an integral portion of the dispenser210, preferably within the dispenser housing212. The control circuit260is interconnected with the motor220to selectively activate the air compressor222. Similarly, the control circuit260interconnects with the shut-off valve254′ and valve and pressure sensor assembly247to selectively open and close the valves, when appropriate. The proximity sensor252is connected to the control circuit260to provide a signal when hands are present at the proper dispensing location under the dispensing nozzle250. The valve and pressure assembly247can be designed to vent to the atmosphere (under control of the circuit260) if the pressure in the container215becomes too high, or the container215could be fitted with a valve having a set cracking pressure and communicating with the air portion218.

In the prior embodiments ofFIGS. 1-5, the dispensers are intended to dispense foam and include both air tubes and liquid tubes to advance air and liquid to a foam generator. Realizing that the present concepts can be employed to dispense liquid products that have not been foamed with the addition of air, a liquid dispenser310is shown inFIG. 6. This embodiment is very similar to the embodiment ofFIG. 1and therefore identical numerals are employed to identify identical elements of the dispenser housing12. It will be appreciated that the main distinction between the dispenser310ofFIG. 6and the dispenser10ofFIG. 1resides in the structure of the refill unit314as compared to the refill unit14. Particularly, refill unit314includes only a liquid tube342extending from the sealing cap344and fluidly communicating with the liquid portion316in the container315. This single liquid tube342is preferably flexible so that it may be opened and closed by operation of valve54. Virtually any configuration of components suitable for selectively opening and closing the liquid tube42can be employed, as structures and methods achieving such function are numerous and well known. Additionally, the valve concepts disclosed herein inFIGS. 1,12and13could be employed in particular embodiments, the adaptation of those embodiments to the refill unit ofFIG. 6being readily apparent. In this embodiment, no foam generator is needed. Instead, the liquid tube342extends to a dispensing nozzle350without having to pass through a foam generator. In all other respects, this embodiment is similar to that ofFIG. 1and includes an air compressor22operated by a motor20to force air through compressor tube24and through the inflation plug26. The inflation plug26includes a needle34that extends through a plug receipt335so that the compressor22can inject air into the air portion318of the container315. The inflation plug26can include a pressure sensor28and vent valve30communicating with a control circuit60. A sensor52appropriately positioned to sense the presence of a hand below the dispensing novel50will also communicate with the control circuit60.

In the embodiments ofFIGS. 1,2,4and6, the control circuit60operates the motor20(and thus the air compressor22), the shut-off valve54(or54′), and the pressure sensor28and vent valve30(in embodiments in which the sensor28and valve30are employed) to dispense product, and can do so in numerous ways. The flexibility of the operational mode is apparent, in that the control circuit60may comprise a simple programmable chip, the program achieving the desired operation.

One example of an acceptable operation is illustrated in the flow chart ofFIG. 7, in which a method of operation is designated generally by the numeral400. An initiate cycle402resets the control circuit60and ensures closure of the valves30,54(or54′), as desired. Following the initiate cycle at402, the proximity sensor52is monitored as at404to determine if hands are present. That monitoring continues until a determination is made that hands are present below the dispensing nozzle50,150,350, in which case the motor20is activated as at406, which in turn activates the compressor22to provide compressed air through the tube24, out the needle34and into the air portion18,118,318. The control circuit60continues to monitor the pressure in the air portion18,118,318through the pressure sensor28, as at408. When the pressure P maintained in the air portion18,118,318is equal to dispensing pressure PD, a determination is made, as at410, that dispensing can be engaged, and so the motor is turned off and the shut-off valve54(or54′) opened for a time T1.

In the foam-generating embodiments ofFIGS. 1,2and4, the opening of the shut-off valve54(or54′) will cause air to be driven from the air portion18,118through the air tube40,140, and into the foam generator38,138. It will also cause liquid to be driven from the liquid portion16,116of the container15,115, through the liquid tube42,142and into the foam generator38,138. At the foam generator, the air and liquid mix to create a foam product. For example, the liquid in the container15,115may be chosen to be a foamable soap, in which case a foamed soap is created. In embodiments such as that inFIG. 2, wherein separate sealing structures (55′ and55″) are employed for the air tube and liquid tube, the control circuit60could be programmed to open one tube before another. In the embodiment ofFIG. 6, there is no air tube, and opening the shut-off valve54will cause liquid to be advanced to the dispensing nozzle350. The shut-off valve54(or54′) remains open for a predetermined time T1, this time being an adequate time cycle for dispensing a predetermined volume of foam (or liquid in the case of refill unit314).

It will be understood that when the dispensing valves are opened as at410, the motor20may be turned off under control of the control circuit60. If desired, the motor and compressor may remain on and operative during the dispensing cycle, or the same can be turned off prior to the dispensing cycle, relying upon the pressure head within the air portion18,118,318to effect the dispensing of foam (or liquid only in the case of refill unit314). In either event, once the motor20and compressor22have been turned off and the dispensing cycle has been terminated, action may be undertaken at412to open the vent valve30to vent the pressure head in the air portion18,118,318to atmosphere. The vent valve30may be opened for a set period of time T2sufficient for such venting, or the vent valve30may be opened to atmosphere until the pressure sensor28emits a signal indicating the absence of pressure or the presence of atmospheric pressure. In any event, venting through the vent valve30is desired to prevent over-pressurization of the refill unit14,114,314which may result in a leak or excessively forceful dispensing of foam. Thus, if the pressure in the container15,115,315rises above a set threshold programmed into the control circuit60, the control circuit60will open the vent valve30to reduce that pressure. Similarly, the vent valve30could be designed to have a cracking pressure at which it would open, and thus the threshold pressure would be designed into the vent valve30, and the control circuit60would not have to be programmed with respect to this pressure venting feature.

A second example of an acceptable operation is illustrated in the flow chart ofFIG. 8, wherein a method of operation is designated generally by the numeral500. In this operational mode, it is intended that the refill unit14,114,314always be pressurized to an appropriate pressure when at rest, i.e., when no hands are present at the sensing position of the proximity sensor52. In this way, when a hand is sensed by the proximity sensor52there is no need for the system to begin pressurizing the refill unit14,114,314as in the prior operation mode disclosed above. Instead, the shut-off valve54(or54′) can simply be opened for the appropriate amount of time to dispense a desired dose of product at dispensing nozzle50.

InFIG. 8, an initiate cycle502resets the control circuit54and ensures closure of the shut-off valve54(or54′) and vent valve30. Following the initiate cycle at502, the control circuit60constantly monitors the pressure P within the refill unit14,114,314as at504. The pressure P is monitored for comparison against a desired pressure or pressure range herein referred to as a desired pressure PD. At506, the monitored pressure P is compared to the desired pressure PDto determine if P equals PD. Herein, it should be understood that, if PDis a pressure range, P equals PDwhen P is within that pressure range. If the monitored pressure P is not equal to the desired dispensing pressure PD, the monitored pressure P is compared to the desired pressure PDto determine if P is less than PD, as at508. If the pressure P is less than PD, the motor is turned on, as at510, and, if the pressure P is not less than PD, it is necessarily greater than PD, as determined at512, in which case the pressure is released by venting the refill unit14,114,314at the vent valve30of the inflation plug26, as at514. Whether the motor20is turned on, as at510, or the vent valve30is opened, as at514, the pressure P is monitored, as at504, and, once the pressure PDis reached, either the motor is turned off, as at516,518, or the vent is closed, as at520,522, to establish the pressure P at the desired pressure or pressure range PD. Through such pressurizing and/or venting, as necessary, the pressure P is brought to the desired dispensing pressure or pressure range PD, and the system can then monitor proximity sensor52, as at524, to determine if hands are present.

At526, if hands are not present, the control circuit continues to monitor the pressure, as at504, and to make adjustments thereto, if necessary, as at510and514. This monitoring helps to ensure that any pressure loss, as perhaps through imperfect seals at plug receipt35,135,335or sealing cap44,144,344is corrected, as well as any pressure gain, perhaps through a rise in temperature within the refill unit14,114,315.

In the foam-generating embodiments ofFIGS. 1,2and4, if hands are present when the pressure P is equal to PD, the control circuit60opens the shut-off valve54(or54′), as at528, to allow for air to be driven from the air portion18,118, through the air tube40,140and into the foam-generator38,138. Simultaneously, actuation of the shut-off valve54allows for foamable liquid to be driven from the liquid portion16,116of the refill unit14,114, through the liquid tube42,142and into the foam generator38,138. In embodiments such as that inFIG. 2, wherein separate sealing structures (55′ and55″) are employed for the air tube and liquid tube, the control circuit60could be programmed to open one tube before another. In the embodiment ofFIG. 6, there is no air tube, and opening the shut-off valve54will cause liquid to be advanced to the dispensing nozzle350. The shut-off valve54(or54′) remains open for a predetermined time T1, this time being an adequate time cycle for dispensing a predetermined volume of foam (or liquid in the case of refill unit314) under the desired pressure or pressure range PD. Once the product is dispensed, the system goes back to monitoring pressure at304.

In other embodiments, the air compressor22is designed to generate a maximum pressure, Pmax, which is within the desired dispensing pressure range, PD, such that the refill unit14,114,315is not likely to ever be pressurized to a pressure that is greater than PD, and the vent valve30may be eliminated, along with the venting step in the flowcharts. The elimination of the vent valve30decreases the cost of the inflation plug26. Also, even if the pressure sensor28fails, there is little chance that the pressure in the container15,115,315will exceed the desired range PD.

In the embodiment ofFIG. 5, where the compressor22injects air into the container215through the air tube240, the above procedures generally apply, but the valve and pressure sensor assembly247would function and be controlled substantially as the inflation plug of other embodiments. However, it will be appreciated that the assembly247will have to shut off the air tube240before the shut-off valve254′ is opened to permit dispensing, otherwise the air could be directed toward the air compressor222, thereby affecting the air to liquid ratio realized at the foam generator.

In a particular embodiment in accordance with either the system ofFIG. 7orFIG. 8, the pressure is monitored and maintained at from 2 to 10 psi when the dispenser is unactuated and at rest, i.e., PDis from 2 to 10 psi. In other embodiments, PDis from 3 to 6 psi, and in yet other embodiments, form 3 to 5 psi. In another embodiment, the liquid is chosen from gel hand sanitizer products and liquid soap products, and PDis from 3 to 5 psi.

In a particular embodiment in accordance with either the system ofFIG. 4orFIG. 5, the time T1that the shut-off valve54remains open to dispense product is from 0.01 to 1.0 second. In other embodiments, the time T1is from 0.25 to 0.75 seconds, and, in other embodiments, from 0.25 to 0.5 seconds.

Though in the preferred embodiments shown, the foam generator38,138is shown as being part of the refill unit14,114, it should be appreciated that it would be possible to provide a refill unit14,114having an air tube40,140and liquid tube42,142that are to be mated with a foam generator38,138that remains a more permanent part of the dispenser housing. However it is preferred, as shown, that the foam generator38,138remain a part of the refill unit14,114so that all wetted parts of the dispenser are periodically disposed of to ensure that the dispenser remains sanitary. This concept is well known to be preferable at least the soap and sanitizer dispensing arts. In particular embodiments of this invention, the foamable liquid creating the liquid portion16,116is soap or sanitizer that is capable of foaming when mixed with air. Such soap and sanitizer formulations are currently well known and are continually being developed and improved upon.

Notably, in one or more embodiments, the refill units of the present invention are devoid of any vent valves, which, if employed, are provided as part of an inflation plug of the present dispensers or elsewhere in the more permanent dispenser housings so that the refill units can be manufactured more cost effectively. Additionally, in the present refill units, the air and liquid tubes extend from the bottom of the container, in the dispensing direction, and therefore need not be threaded through the dispenser housing as, for example, in U.S. Patent Application No. 2010/0102083. In preferred embodiments of the present refill units14,114, a single plug receipt presents the only location of the container15,115that is eventually compromised by engagement with a needle34of an inflation plug26. Although tubes such as air tube40, liquid tube42and dispensing tube149do extend through their respective containers15,115of their respective refill units14,114, they extend through sealing caps44,144in air-tight manner that is not easily compromised. The present refill units are devoid of moving parts, the air and liquid being driven therethrough by the air compressor retained by the dispenser housing. The present invention also provides a simplified and improved method for mounting refill units in that the invention proposes that the proper insertion of the refill unit into the dispenser housing can result in the mating of the needle of the inflation plug and the plug receipt of the container, simply by insertion of the container of the refill unit into a pocket of the dispenser housing, where the inflation plug is located to appropriately align with the plug receipt. After such insertion, the tube or tubes extending through the sealing cap of the refill unit can be placed in a channel where valve structures serve to act upon the tube(s) to open and close them as necessary to dispense product.

Thus it can be seen that the various aspects of the invention have been attained by the structure presented and describe above. While in accordance with the patent statutes only the best mode and preferred embodiment of the invention has been presented and described in detail, it will be understood that the invention is not limited thereto or thereby. Accordingly, for an appreciation of the true scope and breadth of the invention reference should be made to the following claims.