PUMP DISPENSER FOR VISCOUS FLUIDS

Abstract: A viscous product dispenser is described which comprises a tubular container body (11) adapted to hold product, a take-up piston (13) at the lower end of the body (11) which decreases the internal volume of the container as product is dispensed from the container, and a bulk liquid pump dispenser (14) at the upper portion of the container body (11) having a product inlet extending into the container body (11) and a finger depressible, spring-biased piston/cylinder pumping mechanism. The pumping mechanism of the bulk liquid pump dispenser (14) has a product outlet conduit which is parallel and coaxial to the outlet axis of the product inlet and the center of the piston (13). The piston/cylinder pumping mechanism is of substantially less cross-sectional area than the internal diameter of the container body (11). The take-up piston (13) can have a central depression to accommodate the lower portions of the housing of the pump dispenser (14) when the piston (13) reaches its uppermost location when the container is nearly fully evacuated of product. Transverse slot means cut downwardly in the upper surface of the piston (13) extend radially outwardly from the central depression to the sides of the piston (13) to provide a means to bleed or vent off unwanted air entrapped in product which lies in the central depression.

Description: The present invention is a pump dispenser for viscous fluids, namely creams, lotions, and the like. The prior art shows a variety of dispensers for fluid masses which comprise a generally tubular container with a pumping mechanism at one end and a take-up piston at the other. In such dispensers, the pumping mechanism is adapted to dispense the product from the container. As products is removed from the container which holds it, the take-up piston is moved by atmospheric pressure towards the pumping mechanism to insure that the fluid product and any associated reservoir in the pumping mechanism do not develop unwanted voids or open spaces which would interfere with the desired dispensing action on subsequent uses of the dispenser. One approach to the design of an appropriate pumping mechanism for one end of such containers is to provide a container body part which is resiliently compressible to effect a decrease in volume of a pumping chamber so as to cause the dispensing of product from the container. Examples of devices which use such an approach are US Patent Nos. 3,088,636; 3,361,305; 3,768,705; 4,154,371; 4,402,431; 4,413,759; 4,442,958; 4,474,313; and 4,533,069. An alternative approach to the design of an appropriate pumping mechanism for tubular containers having a take-up piston at its opposite end is to provide a pumping dispenser having movable, rigid members which effect an appropriate volume reduction in a reservoir to dispense product therefrom. The following patents have been noted as following this approach: US Patent No. 4,301,948 to J Czech illustrates a pumping mechanism which comprises a head member in the form of a substantially cylindrical cap which is slidely supported on an outer side wall surface of the container. Movement of the head member towards the tubular container effects a reduction in a pump chamber containing the product to effect dispensing of the product through a suitable outlet in the head member. US Patent No. 4,323,175 to J Eckert illustrates a dispenser having a delivery device on the upper side of a supply container, transverse to the main direction in which the supply container extends. This delivery device has a cylinder space in which is arranged a displacement piston which is adapted to be displaced axially. US Patent No. 4,485,943 to J Czech shows a dispenser which utilises a spring-biased piston to effect an appropriate reduction in the volume of a pump chamber. The path of egress of the material from the pump chamber to the outlet first lies in a direction lateral to the path of travel of the piston and thence parallel to the path of travel of the piston but laterally displaced therefrom. US Patent 4,511,068 to J Bossina and 4,598,843 to D D Foster et al both show the use of spring-mounted pistons to effect removal of viscous product from the type of tubular container described before. In both cases the product is dispensed through outlet means in the piston structure initially in the direction that is parallel, and coaxial, with the path of travel of the piston, and the lateral dimensions of the piston are substantially the same as the inner diameter of the tubular container. In other words, the lower surface of the delivery piston at its circumferential portions makes sealing contact with the inner walls of the tubular container. The dispenser defined in the precharacterising part of claim is previously known from US Patent 4,694,977 to Graf (equivalent to EP-A-0,143,183). This document describes a pump system comprising a vacuum-tight storage space having a piston-pump projecting thereinto and a socalled drag piston at the opposite end of the space. As product is discharged from the storage space by the piston pump, the suction connection drags the drag piston up the container behind the decreasing volume of product, the drag piston being shaped so as to cooperate with the piston-pump (see, for example, figure 7 of this patent). It is generally known in the prior art to provide a viscous product dispenser which comprises: a generally tubular container body to hold the product; a take-up piston at the lower end of the body which responds to discharging of product from the container body by shifting its position towards the upper end of the body so as to decrease the internal volume of the container body holding the product by an amount corresponding to the volume of product discharged; and a bulk liquid pump dispenser at the upper portion of the container body which comprises an inlet for product extending into the container body portion intended to hold the product and a finger-depressible, spring-biased piston/cylinder pumping mechanism located within. The liquid pump dispenser has a product outlet conduit which is parallel to the axis defining the inlet for product from he container into the pump dispenser. The product outlet conduit within the pump dispenser is substantially coaxial with the centre of the piston in the pumping mechanism. The piston in the pumping mechanism, which is movable towards and away from a reservoir within the cylinder encasing it, is substantially smaller in width than the internal width of the tubular container. In the dispenser of the present invention modifications have been made to the take-up piston to insure that the piston can advance, to the maximum extent possible, upwardly inside the tubular container body to dispense product therefrom while providing means to vent any undesired, entrapped air within the product holding sections of the container to insure continued functioning of the dispenser. These objects are achieved by the features specified in the characterising part of claim 1. The present invention is further understood by reference to the Drawings which illustrate the present invention wherein: FIG. 1 is an exploded view, in perspective, showing the three major elements of an embodiment of a pumping mechanism; FIG. 2 is a view in partial cross-section showing the parts of Figure 1 as assembled container; FIG. 3 is a cross-sectional view in greater detail of the bulk liquid pump dispenser; FIG. 4 is a cross-sectional, side view of an embodiment of a dispenser according to the invention; FIG. 5 is a plan view from above of the take-up piston of Figure 4; and FIG. 6 is a plan view from below of the take-up piston of Figure 4. FIG. 1 illustrates, in schematic perspective, the three major elements of the container known for example from EP143183 (Graf). The first element is a tubular container 11 having a suitable outlet opening 12 at its upper end. This tubular container, at its opposed open end, is adapted to receive a take-up piston 13 which, under the influence of atmospheric pressure, is urged in an upward direction towards the outlet as product is pumped from the inside of the container 11. The combination of tubular container 11 and take-up 13 is broadly known as indicated by the various US patents referenced hereinbefore. Further details regarding this combination can be found therein. Suitable liquid pump dispensers are readily available from a number of commercial sources including Calmar Inc of Watchung, New Jersey. FIG. 3 illustrates this type of pump dispenser 14 in cross-section in more detail. The pump comprises an eductor head 15, a dispenser piston 16, an optional locking ring 17, a caplet 18 and container cap 19, a piston seal 20, a responsor spring 21 and accumulator cylinder 22, and a spherical valve 23. The manner in which the pump dispenser shown in FIG. 3 is used is well known. Briefly stated, when a finger is used to depress eductor head 15, the dispenser piston 16 moves downwardly also moving piston seal 20 downwardly to wipe the interior surfaces of accumulator cylinder 22. This forces product up through an internal bore (not shown) within dispenser piston 16 and out through the communicating outlet bore in the head 15. Check ball valve 23 seals the inlet 24, leading to the container as this occurs preventing the flow of product from cylinder 22 into the container 11. Release of head 15 allows spring 21 to urge the piston 16 back up inside the accumulator cylinder 22 to its original rest position while also allowing for the unseating of check ball valve 23 allowing more product to flow into accumulator cylinder 22 from the container 11. As this is occurring, the follower piston 13 moves upwardly to avoid the formation of air within the container 11. In designing the above system, it is generally preferable to insure that the lower end of the dispenser pump shown in FIG. 3 is substantially on the same level as the upper cap portion of the container 11 so that, when the follower piston 13 arrives at its uppermost position in the container 11, as little product as possible remains undispensed from the container. This is possible because a dip tube (or inductor) is not present at the lower product inlet end of the pump dispenser shown in FIG. 3, although such a component is commonly present in bulk liquid pump dispensers of this type utilised with conventional, fixed bottom product containers. The apparatus of the present invention has certain advantages over conventional dispensers which combine the bulk liquid pump dispenser used herein with a standard bottle not containing a take-up piston. Such conventional lotion pump/bottle dispensers cease to function if heavy viscosity products such as cold cream, petroleum jelly, and the like are contained in the bottle due to cavitation around the dip tube. The present invention solves that problem by the provision of the take-up piston in the dispenser. In regard to the type of dispensers shown in US Patent Nos. 4,511,068 and 4,598,843, the present dispensing system has differing advantages. For example, the present dispenser can be used in an upright, table top position whereas the type of dispensers shown in the two aforementioned patents need to be held and tilted in the hand in order to dispense the product due to the angle of the outlet opening in such dispensers. The present dispenser is a more closed system due to the design of the bulk liquid pump (i.e. the fact that the spring positively is biased against the sealed dispenser piston when the pump is not being used) so that product bearding at elevated temperatures is substantially reduced as compared to the type of dispenser shown in the two aforementioned patents. FIG. 4 illustrates an embodiment of dispenser of the present invention which comprises generally tubular container 11, liquid pump dispenser 14, and take-up piston 13. The type of liquid pump dispenser is as described with reference to Figure 1 to 3 and as shown in Figure 4 is snap fitted to the outlet end 12 a of the tubular container 11, the container having a reduced diameter neck portion 11 a through which a pump housing 14 a of the pump dispenser projects into the container. The degree to which the pump housing 14 a protrudes into the opening 12 will normally affect the degree to which take-up piston 13 can approach the outlet opening of the container 11 in which the pump dispenser 14 is located. The take-up piston 13 in the present embodiment has two essential features which allow for the maximum degree of its upward movement within container 11 to provide for maximum dispensing of product therefrom with provision made for the bleeding off of unwanted air pockets within the material to be dispensed. Firstly, a depression 25 is centrally located in the top surface of the take-up piston 13 to accommodate the lower portion of the housing 14 a of the pump 14 as the piston 13 reaches the uppermost portions of its travel. This allows the piston 13 to approach as close as possible to the top of the container 11 thereby reducing the space in which liquid product is held to the absolute minimum practical extent. Secondly transverse slot means 26 (for example, three slots at 120° to one another) extend downwardly from the top surface of piston 13 and extend from the depression 25 to the side of the piston 13 immediately adjacent the inner wall surface of the container 11. These slots allow for bleeding off of any entrapped air in the product to be dispensed since they allow for the entrapped air to migrate to the interface between the sides of the piston 13 and the inner wall surface of the container 11. The tolerances in sealing fit between piston 13 and wall surfaces are close enough to prevent liquid product from leaking past the piston 13 but not so close to preclude unwanted air from being vented past those surfaces out of the chamber defined by the walls of container 11, piston 13 and pump housing 14 a holding the product. The foregoing is presented for illustrative purposes only and should not, therefore, be construed in a limiting sense. The scope of protection that is sought is set forth in the claims which follow.

Claims: 1. A viscous product dispenser comprising in combination: (a) a generally tubular container body (11) to hold the product; (b) a bulk liquid pump dispenser (14) at the upper portion of the container body which comprises a product inlet (24) extending at least partially into the container body portion intended to hold the product, and a finger depressible (15), spring (21)-biased piston (16)/cylinder (22) pumping mechanism located above the product inlet; (c) a take-up piston (13) at the lower end of the body which responds to discharging of product from the container body (11) by shifting its position towards the upper end of the body so as to decrease the internal volume of the container body holding the product by an amount corresponding to the volume of product discharged; the take-up piston (13) having a depression (25) in its upper surface into which at least a portion of the housing (14a) of the pump dispenser (14) can fit when the take-up piston (13) advances into the upper portion of the container body, characterised in that the take-up piston (13) has transverse slot means (26) communicating with the depression (25) and the side walls of the container body (11) to allow any entrapped air to bleed off from the space within the container between the take-up piston and the housing of the pump dispenser. 2. A dispenser as claimed in claim 1 characterised in that three slot means (26) communicate with the depression (25) and side walls. 3. A dispenser as claimed in claim 2 characterised in that the three slot mens (26) are at 120° angles to one another. 4. A dispenser as claimed in any one of claims 1 to 3 characterised in that the pump dispenser has a check valve (23) in its product inlet (24).

Inventors: GENTILE, JAMES L., LA ROSA, JOSEPH P., RAINEY, DEAN R.
Applicants: UNILEVER N.V., UNILEVER PLC
Application year: 1988
Main classification: B65D47
IPC codes: B05B11, B65D47, F04B9