Patent Application
20080277421
The present invention generally relates to gear pumps, and, more particularly, to gear pumps employed to mix two or more components. In a particular embodiment, this invention relates to a dispenser employing a gear pump to dispense a foam product.
Gear pumps have been used to mix multiple components, as will be seem from a review of the following U.S. Pat. Nos.: 2,324,116; 3,628,893; 3,764,238; 4,059,714; 4,193,745; 4,264,214 and 4,601,645. Although these various patents disclose gear pumps that mix two components, it is significant to note that they mix those components within the housing for the gears of the gear pump. In accordance with the present invention, a gear pump is provided wherein two components are mixed otherwise than only within the housing that holds the gears. Specific embodiments are directed toward the dispensing of foam products for skin care and skin sanitizing, but this invention will have wider application to the mixing of any components suitable for being pumped in accordance with the teaching herein.
With respect to the dispensing of skin care and skin sanitizing products, in the current state of the art, it is common to provide dispensers wherein a permanent housing is provided to receive disposable refill units that include a suitable skin care or skin sanitizing liquid container with associated pump mechanisms. The refill units are received in permanent housings, which provide elements for actuating the pump mechanism provided by the refill unit. When the container of the refill unit is empty, it is simply replaced with a new refill unit. The pump mechanisms in these refill units are of various types, including, most commonly, piston-type and diaphragm-type pumps and, less commonly, gear pumps (as in U.S. Pat. No. 5,836,482). In at least the skin care and skin sanitizer dispensing arts, the diaphragm-type pumps are also commonly known as “dome pumps.” The piston-type and diaphragm-type pumps have been adapted to produce a foam product. However, the gear pumps employed in dispenser refill units have not been adapted to produce a foam product, and the present invention addresses this need in the dispensing arts, while more broadly providing pump and dispenser mechanisms suitable for dispensing virtually any suitable component or components.
This invention provides a gear pump for mixing first and second components. The gear pump includes an inlet port, a premix chamber, and a second component valve. The premix chamber has a first end communicating with the inlet port, and a second end communicating with a source of the first component, thus providing a fluid path to carry the first component through the inlet port upon operation of the gear pump. The second component valve regulates fluid communication between a source of the second component and the premix chamber. Upon operation of the gear pump, the first component is drawn from its source into the premix chamber, the second component is drawn from its source, through the second component valve, and into the premix chamber, and a premix of the first and second components is fed from the premix chamber through said inlet port.
In accordance with another embodiment, this invention provides a dispenser that includes a housing that retains a refill unit. The housing has a motor mounted thereto, and the motor provides an output shaft that rotates upon operation of the motor. The refill unit includes a first component container and a gear pump. The first component container retains a first component for dispensing. The gear pump includes a pump housing and has a first gear retained in the pump housing, the first gear having an axis of rotation and radially extending teeth. The output shaft of the motor engages the first gear to rotate the first gear upon operation of the motor. A second gear is retained in the pump housing, the second gear having an axis of rotation and radially extending teeth, wherein the radially extending teeth of the first gear intermesh with the radially extending teeth of the second gear at a nip such that rotation of the first gear effects the rotation of the second gear. During such rotation, the radially extending teeth of the first and second gears engage to intermesh on one side of the nip and disengage from intermeshing on the other side of the nip. An inlet port communicates with the pump housing on the side of the nip where the radially extending teeth of the first and second gears disengage from intermeshing, and an outlet port communicates with the pump housing on the side of the nip where the radially extending teeth of the first and second gears engage to intermesh. The refill unit also includes a premix chamber having a first end communicating with the housing, through the inlet port, and a second end communicating with the first component retained within the first component container, thus providing a fluid path to carry the first component into the pump housing. The refill unit also includes a second component valve regulating fluid communication between a second component and the fluid path of the premix chamber. Upon rotation of the first and second gears, the first component is drawn through the fluid path of the premix chamber and the second component is drawn through the second component valve into the fluid path and a premix of the first and second components is fed to the pump housing through the inlet port.
For a complete understanding of the objects, techniques and structure of the invention, reference should be made to the following detailed description and accompanying drawings wherein:
Referring now to
With reference to
Pump housing 38 defines a first gear portion 54 that retains a first gear 56, and a second gear portion 58 that retains a second gear 60. The first gear 56 includes radially extending teeth 62 that engage the sidewall 64 of the first gear portion 54. Similarly, the second gear 58 includes radially extending teeth 66 that engage the sidewall 68 of the second gear portion 58. The radially extending teeth 62 and 66 intermesh at nip 70, where the teeth 62, 68 of the first and second gear portions 54, 58 overlap.
The pump housing 38 is associated with, and, in this particular embodiment, is molded as part of a motor mount member 72. A drive shaft 74 extends from the motor 24, through a shaft aperture 75 in the pump housing 38, into the interior of the first gear portion 54 to engage a drive aperture 76 in the first gear 56. The drive shaft 74 engages the drive aperture 76 such that rotation of the drive shaft about its axis also causes rotation of the first gear 56. This can be accomplished in a number of ways and is accomplished in particular embodiments by having a non-circular shape for the drive aperture 76, and a complimentary shape for at least that portion of the drive shaft 74 that extends into the drive aperture 76. The motor mount member 72 is shaped such that it is securely received over the motor 24, as shown. In some embodiments, this engagement can help hold the refill unit 12 to the backplate 16 of the dispenser 10. It also helps to align the drive shaft 74 of the motor 24 with the shaft aperture 75 and the drive aperture 76. In the embodiment shown, the motor mount member 72 fits over the motor 24 and engages it through a snap fit, and, as the motor mount member 72 mates with the motor 24, the drive shaft 74 mates with the drive aperture 76. A seal 78 is provided in the pump housing 38, between the first gear 56 and the pump housing 38, to prevent leaking from pump housing 38 at shaft aperture 75. Once the refill unit 12 is mounted to the dispenser in this manner, the motor 24 can be operated to rotate both first gear 56 and second gear 60, with the second gear 60 being driven due to its intermeshing with the first gear 56 at nip 70. It is the driving of the gears 56, 60 that causes the pumping of foamable liquid and air to create the desired foam product at dispensing tube 30.
More particularly, as seen in
The premix is drawn from the inlet port 48, through the inlet path 82, toward the nip 70. As the premix approaches the nip 70, it becomes impounded between adjacent teeth of the first and second gears 56 and 60, and is carried between the teeth and the pump housing 38 to be circumferentially moved from the inlet path 82, where the teeth 62, 66 disengage, to the outlet path 84, where the teeth 62, 66 engage. Positive pressure is created where the teeth engage such that the premix that is moved to the outlet side of the nip 70 is forced through the outlet path 84 to the outlet port 50 communicating with the dispensing tube 30. Thus, as the first gear 56 and the second gear 60 are rotated within their respective first and second gear portions 54, 58, a premixture of air and foamable liquid S is created at the premix chamber 40, from where it is drawn through the gear pump housing 38 and forced out at the outlet port 50.
The premix that is carried between the teeth 62, 66 of the first and second gears 56, 60 is further homogenized at the outlet path 84 inasmuch as discreet volumes of the premix held between adjacent teeth are forced into each other at the outlet path 84. In some embodiments, this might create a satisfactory foam product at outlet port 50. In such a case, the dispensing tube 30 could simply be a conduit for the foamed product, and would be of a length suitable for whatever particular dispenser style is practiced. In the present figures, a wall-mounted dispenser has been the focus, but other dispensers, including hand held and counter-mounted types could be practice with the container and pump combination disclosed herein. In other embodiments, the mixing effected at the outlet path 84 may not be sufficient for creating a suitably homogenized foam product, and, in such instances, it is preferred that the dispensing tube 30 include a mixing chamber for homogenizing the foam and producing a desired foam product.
As seen in
The foam adjustment valve 80 is manipulated to adjust the amount of air drawn into the premix chamber 40 during rotation of the gears 56, 60. While virtually any valve that would function appropriately for this purpose could be employed, a particular embodiment is shown in
The adjustment valve housing 94 also defines a seal chamber 100 and a threaded shaft chamber 102, both of which also communicate with the air path 96 and the air port 98. An adjustment valve shaft 104 mates with the adjustment valve housing 94, and is manipulated to selectively open and close the air port 98 to a greater or lesser degree to permit the passage of more or less air into the premix chamber 40 during rotation of the gears 56, 60. More particularly, a threaded section 106 of the adjustment valve shaft 104 extends from a knob 108, and is threaded to the threaded shaft chamber 102. A seal section 114 of the adjustment valve shaft 104 engages the seal chamber 100 of the adjustment valve housing 94 through an O-ring 116 such that the air path 96 is sealed from the threaded shaft chamber 102. A needle head 118 extends from seal section 114 of the adjustment valve shaft 104, across and through the air path 96, and ends at a valve seat 120. The needle head 118 is sized at least slightly smaller than the air path 96 so that air may flow in air path 96.
As in
It should be appreciated that the refill unit 12 shown in the drawings is particularly useful in the wall-mounted dispenser embodiment of dispenser 10 (
If the drive shaft 74 is continuously driven, the foamable liquid and air components will be continuously drawn into and expelled out of the gear pump assembly 26. While this may be appropriate in some applications, it is envisioned that, in some embodiments, as, for instance, in the creation of a foam soap, only “doses” of the end product will be desired. When this is the case, the drive shaft 76 is preferably only driven for a time sufficient to expel a desired dose of the mixed product. The time that the drive shaft 76 will have to be driven will depend upon the desired dose of the mixed product and the flow through rate for the gear pump assembly 26.
In a foam soap embodiment using foamable liquid soap, the foam adjustment valve is adjusted such that the ratio of air to liquid soap drawn into the pump housing is from 30:1 to 3:1. In a particular embodiment the ratio maybe 20:1 to 5:1, and in other embodiments from 12:1 to 8:1.
It should be appreciated that the refill units taught herein could be employed in various dispensers for supplying various mixed products, whether those products are simple single component products (when the air inlet at the foam adjustment valve is closed) or foam products of liquid and air mixtures or mixtures of two liquid components, either with or without air incorporated therein (a liquid/liquid mixture is discussed below). Thus, a particular refill unit might be provided having a particular component therein, and such refill units will be particular to a given desired application. In such a situation, it will be important to avoid inserting a particular refill unit into a dispenser that is designated for a different refill unit. For example, it would be important to avoid inserting a hand soap refill unit into a hand sanitizer dispenser. Therefore, the refill units and dispenser housings of this invention could optionally be provided with physical or electronic keying systems to either prevent the loading of an improper refill unit into a given dispenser or allow the loading, but prevent dispensing. A physical or electronic keying system would be established between a given dispenser and a given refill unit. If the key on the refill unit does not match up with the key on a dispenser housing, then either loading of the refill unit or dispensing of the product would be prohibited.
In accordance with the teaching herein, it should be appreciate that this invention need not be limited to the mixing of a single liquid component with air. Other gases could be introduced at foam adjustment valve 80, simply by associating that valve with a particular gas source. Also, as generally represented in
It should also be appreciated that, although this invention provides advances in mixing multiple components within a gear pump, gear pumps are generally known. This invention has provided specific embodiments employing external gear pump designs, but it should be appreciated that the teachings herein may be followed with internal gear pump designs as an alternative.
It is a common problem with foam dispensers that they might drip when the foam product breaks down back to its liquid component or components. This is particularly true when the outlet of the dispenser points downwardly, because simple gravity will cause the liquid component to drip out of the outlet. The present invention can be used to counteract this dripping by reversing the motor for a short time after a given product dispensing. The reversal of the motor will result in a reversing of the areas of positive and negative pressure in the pump assembly (i.e., during reversal, the teeth will part where they usually join during dispensing, and will join where they usually part during dispensing), and this will cause a reversal of product flow, thus pulling foam product back from the outlet. The extent to which the motor is reversed will depend upon how far back the product must be pulled to prevent dripping. For example, in the embodiment shown in
In light of the foregoing, it should thus be evident that the present invention provides a gear pump and foam dispenser that substantially improves the art. In accordance with the patent statutes, only the preferred embodiments of the present invention have been described in detail hereinabove, but this invention is not to be limited thereto or thereby. Rather, the scope of the invention shall include all modifications and variations that fall within the scope of the attached claims.
