Dispenser pumps

Details Dispenser pumps Dispenser pumps

2001-09-12

2003-09-02

Kaufman, Joseph A. (Department: 3754)

Dispensing

With material treatment or conditioning means

C222S321400, C222S481500

Reexamination Certificate

active

06612468

ABSTRACT:

FIELD OF THE INVENTION
The present proposals have to do with hand-operated dispenser pumps, and partially in certain aspects to such pumps adapted for the dispensing of foam from a supply of foamable liquid in a container to which the dispenser is fitted.
BACKGROUND
Over the last 15 years or so the use of foam dispensers based on aerosols using pressurized gas has declined steeply for environmental reasons, leading the development of foaming dispensers which exploit a manual pumping action to blend air and liquid and create foam.
A particular category of such known dispensers to which certain of the present proposals relate (referred to in what follows as foaming dispensers “of the kind described”) provides both a liquid pump and an air pump mounted at the top of a container for the foamable liquid. The liquid pump has a liquid pump chamber defined between a liquid cylinder and a liquid piston, and the air pump has an air pump chamber defined between an air cylinder and an air piston. Preferably these components are arranged concentrically around a plunger axis of the pump. The liquid piston and air piston are reciprocable together in their respective cylinders by the action of a pump plunger: typically the two pistons are integrated with the plunger. An air inlet valve and a liquid inlet valve are provided for the air chamber and liquid chamber. An air discharge passage and a liquid discharge passage lead from the respective chambers to an outlet passage by way of a permeable foam-generating element, preferably one or more mesh layers, through which the air and liquid pass as a mixture. Preferably the air discharge passage and liquid discharge passage meet in a mixing chamber or mixing region immediately upstream of the permeable foam-generating element.
It is not easy to achieve a good quality foam consistently from dispensers of the kind described. There are also difficulties in providing for adequate venting and valving of the different fluid spaces and paths while assuring a positive operation without leaks.
EP-A-565713 (equivalent to U.S. Pat. No. 5,271,530) describes admitting air to the air cylinder through a ball valve in the top wall of the air piston. This does not work when wet, nor when the plunger is pressed slowly, and there is a problem of liquid entering the air chamber via the mixing chamber and air discharge passage.
EP-A-613728 refines the air valving using a single elastomeric annulus in the air piston roof whose outer rim acts as an air inlet flap valve and whose inner rim acts as an air discharge flap valve against the plunger stem. This arrangement dispenses air at all speeds and helps prevent liquid getting into the air chamber.
WO-A-97/13585 notes a tendency for such a double-acting valve element to stick, and addresses this by providing some axial play between the plunger stem and the air piston. This play is taken up in alternating directions as the plunger reciprocates, keeping the valve element moving freely.
EP-A-736462 is another system using axial lost motion between air piston and plunger, for a double-acting valve action via holes near the inner periphery of the air piston roof.
Our present proposals provide new and useful developments in various aspects of the construction of dispensers, particularly foam dispensers of the kind described. A first set of aspects is concerned with the venting and valving of air flows in relation to the air chamber. A further aspect relates to venting in plunger operated pumps in general. Other aspects relate to a new overall disposition of the pump parts.
A first proposal herein is that the plunger includes a cap shroud whose outer skirt continues down and connects fixedly or integrally adjacent the air piston's peripheral seal, defining thereby an internal cap air chamber above a roof of the air piston, enclosing the air inlet valve. Access for exterior air to the air chamber in the air cylinder is then via this internal cap air chamber. External air may enter the cap through one or more holes in the cap shroud e.g. holes above where the cap shroud projects through a guide opening of a fixed pump body.
A further independent but combinable proposal herein is that the air inlet valve through which air enters the air chamber comprises a radially inwardly-projecting flexible valve flap formed integrally with at least an outer sleeve portion of the air piston, carrying or including a seal portion shaped to engage the air cylinder wall. In a preferred embodiment this outer sleeve of the air piston is fixed directly to a cap shroud of the plunger which encloses the air inlet.
The air inlet valve flap, which preferably extends substantially in a radial plane and is preferably a uniform annulus, is flexible relative to an air inlet valve seat. A preferred valve seat is a downwardly-directed edge, especially an annular edge, of a core sleeve comprised in the pump plunger and which moves axially, preferably fixedly, with the pump plunger.
Desirably the components of the pump plunger are fixed together in pre-determined axial register so that the air inlet valve flap is resiliently urged axially against the air inlet valve seat, such as the annular edge of a core sleeve as mentioned. The air discharge passage may lead up inside such a core sleeve. The core sleeve may then also provide a valve seat for air outlet valve flap which is provided on a radially inner plunger core portion. Or, the core sleeve may itself comprise integrally an air outlet valve flap e.g. extending from at or from adjacent the seat edge engaged by the inlet valve flap. Thus, in one preferred embodiment the air inlet valve flap extends radially relative to, e.g. inwardly of, the core sleeve, and an air outlet valve flap extends radially (or at least, with a radial component) out towards or in from the core sleeve. Such a core sleeve preferably encloses an annular air discharge space, all or partly downstream of the air outlet valve when one is provided, and communicating (from downstream of any such outlet valve) inwardly (optionally also upwardly) to a mixing chamber for liquid and air. Such a mixing chamber and/or the point(s) of air injection into such a mixing chamber is preferably axially overlapped by the annular air discharge space in the core sleeve. This gives an axially compact construction.
The core sleeve in any of the other embodiments may be constituted by a downward skirt from a plunger component. This skirt may include a core part projecting down inside the core sleeve at a radial spacing. This inner core part might be for example a surround to a mixing chamber, through which the air is injected, and/or part of a plunger stem which is or carries the liquid piston.
A further proposal herein is that the air outlet valve is provided as an upwardly diverging conical or cup-shaped element, sealing outwardly against an inwardly directed air discharge passage wall, such as that of a core sleeve as mentioned above, or some other part of the air discharge passage. A benefit of this air outlet valve conformation is that it catches drops of liquid escaping from the foam-generating region and helps prevent them from reaching the air chamber.
Further aspects herein relate to modes for arranging the mixing of liquid and air. Typically the liquid discharge passage rises axially from the liquid chamber in the liquid cylinder. The liquid discharge passage may extend up inside a hollow stem inside the plunger. A liquid discharge valve is usually provided for this passage. We prefer to provide the valve at the entrance to the passage e.g. by means of a sliding seal on the liquid piston which covers and uncovers windows in the hollow stem However, it would also be possible to provide a liquid discharge valve midway along the liquid discharge passage, as in the prior art patents mentioned above. Preferably a mixing chamber or region where air and liquid are present together is provided immediately upstream of the foam-generation element. We prefer that at or immediately before this mixing chamber the liquid discharge passage diverges around a centr

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