Foam dispensers

Abstract

A foam dispenser has a foam-generating pump (1) mounted on a container (100) to hold liquid. The pump (1) has a liquid intake conduit with a ball valve (27) and an air intake conduit (45) provided partly by a jacket component (4) fitting around the pump body (2) with clearance. The pump has structure defining a mixing zone (50) for mixing air and liquid, a foam chamber (28) for holding foam received from the mixing zone, and a discharge conduit leading from the foam chamber to a discharge outlet (36). The mixed air and liquid pass through a permeable foam regulator mesh (54). One or more air inlets (47) lead into the mixing zone (50) from the air intake conduit (45). A liquid inlet in the form of a restricted jet orifice (89) leads into the mixing zone (50) from the liquid intake conduit, upstream of the inlet ball valve (27). A regulator mesh (53) is also provided between the liquid inlet and mixing zone.

Claims

1. A foam dispenser comprising a container to hold liquid and a foam-generating device mounted on the container; the foam-generating device comprising a liquid intake conduit, an air intake conduit, structure defining a mixing chamber for mixing air and liquid from these conduits, a foam chamber for holding foam received from the mixing chamber, a discharge conduit leading from the foam chamber to a discharge outlet and an actuator for driving foam from the foam chamber along the discharge conduit to the discharge outlet; one or more air inlets opening into the mixing chamber from the air intake conduit and one or more liquid inlets opening into the mixing chamber from the liquid intake conduit; the or each said liquid inlet entering the mixing chamber by way of a permeable regulator element including a mesh, a check valve between the permeable regulator element and the discharge outlet; a body component defining the foam chamber and an air conduit jacket component fitting around the body with clearance between the jacket component and the body providing all or part of the air intake conduit; and wherein the or each said air inlet enters the mixing chamber directly without passing through a permeable regulator element.

2. The foam dispenser of claim 1 wherein the check valve is positioned between the mixing chamber and the foam chamber.

3. The foam dispenser of claim 1 wherein a said liquid inlet comprises a restricted jet with a jet orifice.

4. The foam dispenser of claim 3 wherein the liquid inlet has a closed bore between the restricted jet orifice and the regulator element, and the air inlet(s) is/are outside the closed bore.

5. The foam dispenser of claim 1 wherein the or each air inlet comprises a restricted jet.

6. The foam dispenser of claim 1 wherein the flow cross-section area of the one or more air inlets is less than the flow cross-section area of the one or more liquid inlets.

7. The foam dispenser of claim 1 wherein the foam-generating device comprises a pump mechanism for expelling foam from the foam chamber through the discharge conduit, the foam chamber being a pump chamber of said pump mechanism and the actuator being moveable to alter a volume of the foam chamber to expel foam through the discharge conduit.

8. The foam dispenser of claim 1 wherein one or more air inlets of the air intake conduit are defined as channels between fitting surfaces of discrete components of the foam-generating device.

9. The foam dispenser of claim 1 wherein a volume of the foam chamber is from 1 ml to 10 ml.

10. The foam dispenser of claim 1 wherein one or more permeable foam regulator elements is provided in the discharge conduit or at the discharge outlet.

Description

(1) An embodiment of our proposals is now described by way of example, with reference to the accompanying drawing figures in which:

(2) FIG. 1 is an axial cross-section, at a plane A-A marked in FIG. 2, of a foam-generating device embodying our proposals, specifically a foam dispenser pump;

(3) FIG. 2 is a rear elevation of the foam dispenser pump;

(4) FIG. 3 is a fragmentary view showing the top of the pump connected to a container;

(5) FIG. 4 is an enlarged radial cross-section at IV-IV of FIG. 12

(6) FIG. 5 is an enlarged radial cross-section at V-V of FIG. 2;

(7) FIG. 6 is an enlargement of a central part of the pump in a sectional view as in FIG. 2;

(8) FIG. 7 is a corresponding enlargement of an inlet part of the pump, and

(9) FIGS. 8, 9 and 10 are enlarged radial cross-sections at VIII-VIII, IX-IX and X-X of FIG. 2 respectively.

(10) With reference to the drawing figures, a foam dispenser pump 1, being an embodiment of the foam-generating device of our proposals, comprises generally a pump body 2 including a cylinder 21 defining a pump chamber 28 which is a foam chamber for the device and a plunger 3 mounted to reciprocate relative to the body 2, with a spring 51 acting between them and tending to push the plunger 3 up to the extended position shown in the figures. The body 2 is mounted in the threaded neck 101 of a container 100shown fragmentarily in FIG. 3by a closure cap 9 having internal threads 91 and a top inward flange 92, The pump body has an outward mounting flange 24 at the top of the cylinder which rests on the container neck 101 and is clamped against it by the cap flange 92 through a seal ring 11. See FIG. 6. Above the mounting flange 24 the body 2 has an upward tubular top projection 25 with snap formations on its outer surface.

(11) A body insert 6, generally tubular in form, fits into the top of the cylinder 21see FIG. 6. It has a generally cylindrical side wall 61 fitting with slight clearance into the cylinder to occupy an upper part thereof. It has an inturned floor 62 at the bottom with a central hole 63 for passage of the plunger stem 33, and a top collar 64 projecting first out and then down with a securing skirt. The securing skirt has an inner annulus 65 which snaps onto the securing snap formations of the top projection 25 of the body 2, and an outer annulus 66 which is spaced from itand therefore not distorted when it is fitted onand carries an external lock-down thread formation 68. The top of the body insert 6 has a circular opening for passage of the plunger, with a surround or lip 67 to contact the plunger exterior.

(12) The plunger 3 is in many respects conventional for a movable-nozzle dispenser, having a tubular stem 33 plugged into a socket in the bottom of an actuator head 31 having a laterally-projecting nozzle 32 with a discharge outlet 36 at its end. Towards the top of the plunger, an inner dependent shroud 311 projects down from the plunger head at a spacing around the stem 33 to cover the spring 51 and slidably enter the body insert surround opening 67.

(13) At its bottom end the stem 33 has a pair of flow windows 34 (FIGS. 1, 5 and 6) through which foam from the chamber 23 can enter the discharge conduit 35. The discharge conduit 35 is defined up inside the stem 33 and along inside the nozzle 32. To control the flow openings 34 and drive dispensing of foam the stem carries a sliding piston 7 having outwardly-directed sealing lips 71 wiping the inside wall of the cylinder 21 and an inner sleeve 76 comprising a top abutment ring 72 to engage against the underside of the floor 62 of the body insert 6, and a bottom closure skirt 75 whichas shown in the figurescan abut against a counter-surface of the stem 33 to close off the flow windows 34. Specifically, with the plunger 3 extended as shown under the force of the spring 51 (which is in compression) the stem 33 is pushed up relative to the piston 7, urging the closure skirt 75 against the counter-surface of the stem and preventing any flow. This relative position also holds when the plunger is rising after being depressed, so that suction in the chamber 28 draws liquid in through the inlet described below. When the plunger is pushed down, the stem 33 moves down before the piston 7until the abutment shoulder 74 is engagedso that the flow openings 34 open for the discharge of foam.

(14) Returning to the plunger head 31; a nylon foam-regulator mesh 54 is bonded over the discharge outlet 36. This is a convenient place for attaching mesh and produces good foaming results. Or, a discrete end insert, of the nozzle (not shown) can be used to trap a mesh in place instead of bonding. Another option is to install a mesh inside/under the head at the top of the stem 33, where it can easily be trapped on assembly. Finally, the head has an outer dependent skirt 312 carrying inwardly-directed lock-down threads 38 which can be screwed onto the lock-down thread 68 of the collar 64 when the plunger is fully depressed. In this position an annular bottom projection 39 of the stem 33 seals around above the inlet valve 27 of the cylinder 21 so that product cannot escape from the pump e.g. during shipping.

(15) Next, the special adaptations for forming foam are described. Most of the features described above except the mesh are present in normal liquid pump dispensers. In fact it is a virtue of our proposals that they can be embodied using largely conventional components, and indeed can be used to adapt a pre-existing liquid pump dispenser design to dispense foam instead.

(16) An air jacket 4 with a generally cylindrical main wall 41 fits concentrically over the body cylinder 21, with its circular top edge approaching but not reaching the top of the cylinder 21 and with clearance between them at the top for air entry. The inside surface of the jacket wall 41 has shallow axial ribs 44 (see FIGS. 4 and 5) to maintain clearance between the jacket 4 and cylinder 21 for air flow; this constitutes part of an air intake conduit 45. Each of the cylinder 21 and jacket 4 has a convergent portion 22, 42 towards its lower end. In the cylinder 21 this convergent portion houses an inlet valve 27 with a valve ball 273, valve seat 271 and valve ball retainers 272 above. See FIG. 7. Below the inlet valve the body 2 has a downwardly-projecting cylindrical inlet end tube fitting 23.

(17) The convergent portion 42 of the air jacket 4 leads to a bottom tubular extension 43, and this stands at a radial clearance from the outside of the body 2 so that the air intake conduit 45 continues between them as indicated by arrows in FIG. 7. At its bottom end the jacket component 4 is formed with an inner upward fitting tube 48 and a coaxial downward fitting tube 46 both defining a central bore 49. The outside of the upward fitting tube 48 has a smooth cylindrical surface interrupted at diametrically-opposed points by two axially-extending grooves 47see also the section of FIG. 8. The cross-sectional area of each of these grooves is e.g. from about 0.02 to about 0.05 mm.sup.2, the total area of the combined grooves being e.g. from 0.04 to 0.1 mm.sup.2. The top of the fitting tube 48 plugs into the bottom of the inlet end tube 23 of the body 2 with a close fit, excepting that the mentioned grooves or channels 47 provide for a restricted or jet air flow of corresponding area (by opposing plain cylindrical surfaces on the tube fitting 48) and are air inlets or air inlet jets constituting the final part of the air intake conduit 45 as indicated by the arrows in FIG. 7. They lead into the mixing chamber 50 defined by the inlet valve, the end tube 23 of the body and the upward fitting tube 48 of the jacket 4. A nylon regulator mesh 53 is bonded over the top of the upward fitting tube 48, covering the bore 49. This mesh does not cover or interfere with flow from the air channels or jets 47.

(18) A dip tube adaptor 8 plugs into the cylindrical opening defined by the downward fitting tube 46 of the air jacket 4. Between the upward and downward fitting tubes 48, 46, where the jacket 4 defines the through-bore 49, a downwardly-directed annular shoulder 461 is provided and this provides a seat for a solid orifice piece 88, in the form of a short cylindrical cap with a small central orifice 89 or jet bored through its top layer. The jet orifice piece 88 is trapped in position by plugging the adaptor 8, which has a corresponding inner plug formation 81, into the downward fitting tube 46. The adaptor 8 also has an outer upward retaining skirt 82 and, projecting downwardly, a dip tube socket 83 with an internal stop shoulder 84 to position the end of the dip tube 52. In this particular embodiment the internal diameter of the dip tube 52, and of the adaptor 8 and orifice piece 88, is about 2 mm while the diameter x of the jet orifice 89 at the top of the orifice piece 88 is about 0.4 mm, so the orifice cross-sectional flow area is about 3 to 4% of that of the tube immediately upstream thereof.

(19) Operation of the device is readily understood. The user repeatedly presses and releases the head 31 of the plunger 3. On each upstroke the seal of the sliding piston closes, suction is generated in the chamber 28 and both liquid and air are drawn towards the chamber, via the mixing chamber 50 and valve 27, from their respective inlets. Air for this purpose enters the top of the air jacket 4 recessed up inside the neck of the container, avoiding the entry of liquid. Liquid rises up the dip tube and enters through the narrow jet 89. The sizes of the restricted inlet openings are selected so that the proportions of the liquid, arriving in a turbulent jet and passing through the mesh 53, and of air arriving at high velocity through the small inlet channels 47, are appropriate to form a foam.

(20) A notable feature of this embodiment is that the air does not pass with the liquid through the first mesh 53. This is a desirable and distinctive feature, although alternative constructions can be used.

(21) The inlet valve 27 is open under the suction conditions, so the resulting foam precursor, i.e. turbulently mixed liquid and air in the form of a non-homogeneous foam, fills the pump chamber 28. When the plunger is depressed again, the inlet valve 27 closes, the sliding seal piston 7 opens and foam from the chamber 28 is expelled up the discharge conduit 35 and out through the outlet 36 by way of the second mesh 54 which regularises the bubble size. The dose volume is about 0.4 ml in this embodiment.

(22) It is surprising that foam of good quality can be made and dispensed with such a simple inlet and outlet structure, and with so few meshes/regulators. The use of restricted jet inlets for the liquid, and desirably also for the air, is found to give a good tolerance of the device to varying conditions. In particular, known foamers often perform poorly when the liquid becomes aerated, e.g. if the container has been shaken. The present foamer is found to perform well even under these conditions.

(23) The proportions of air and liquid can readily be adjusted e.g. by adjusting the size of the liquid inlet jet 83. While the jet is provided as a separate component in the present embodiment, this is primarily for versatility. The jet could be provided as a fixed portion of the inlet tube adaptor 8. Indeed the inlet tube adaptor 8 could be integrated with the bottom of the jacket component 4.

(24) While the present embodiment shows an air conduit 45 defined by jacket 4 surrounding the pump cylinder 21, this is not in itself a novel proposal, Other dispositions of air intake conduit may be used, drawing air either from the container interior as in the present embodiment, or from an intake entry at the outside of the device.

(25) Provision is made for air to enter the container, to compensate for dispensed liquid volume, via vent openings 26 (marked in FIG. 6 but not visible per se) around the top of the cylinder 21.