GB2111132A - Dispenser pump - Google Patents

Abstract

A dispenser pump has a discrete cap (6) for securing its body to a container of material to be dispensed. Between the cap and the body a groove in the cap defines an air passage (12) which by virtue of its length and restricted cross-section effectively prevents outward leakage of liquid while permitting access to the container of replacement air. A ledge 12a gives a localised particular restriction of the passage. <IMAGE>

Description

SPECIFICATION Dispenser pump This invention relates to dispenser pumps. In these a valved piston or body is displaced through a defined stroke in order to cause the ejection from the pump of a known volume of liquid or semi-liquid material. Such pumps are best known for dispensing materials such as sauces, ketchups, creams, detergents, cosmetics and the like, but they can in principle also be used for dispensing medicinal or pharmaceutical products, especially for the oral dosing of animals with medicaments or feed supplements.

The present invention is concerned to develop a dispenser pump which is robust, capable of working at any attitude and of being held and operated by one hand.

A particular difficulty in that the pump should be usable in any attitude and with pasty materials, as medicines, sauces, ketchups or feed supplements frequently are, is that of permitting and ensuring access of replacement air. In the present invention this is provided by securing the main body of the pump to a discrete cap which is to cause attachment to a container of material to be dispensed and leaving an air passage between the body and the cap, with access from the interior of the cap to that passage; this will usually be by an orifice through the cap.

It can be seen that the provision of this discrete cap insert means that for a given body moulding a pluraiity of cap inserts may be provided so as to be compatible with a range of envisaged containers.

A local restriction in the passage preferably adjacent where it enters to inside the cap may render the passage effectively impassable to liquids, at least to those of anything but low viscosity, and may take the form of a ledge in a recess cut into the cap and which, with a plain surface of the body, forms the passage.

It is also a feature of the invention that all the parts of the dispenser may be snap-fitted together without the use of adhesive thereby greatly simplifying assembly and cutting down the risk of any contamination or obstruction due to adhesive.

Furthermore, it is preferred that both the body and the piston both be fitted with a nonreturn ball valve whereby a positive and therefore reasonably definite pumping and dosing action is achieved (some dispenser pumps are equipped with one valve only and work against the inherent resistance to movement of the material being pumped).

Embodiments of the invention will now be described with reference to the accompanying drawings wherein: Figure 1 is a side elevation of one embodiment of a dispenser pump; Figure 2 is a vertical section through the embodiment of Fig. 1; Figure 3 is a plan view of a discrete cap part of the assembly; Figure 4 is a vertical section through a second embodiment of a dispenser pump.

In Fig. 1 a pump is seen of which the body 2 is at its rear end a portion which is for reception in the fold of the skin between the thumb and first finger of a user. An upstanding claw 1 assists in that positioning. Below that portion is a skirt 6a within which, as will be described, is a discrete cap for attaching the pump to a container such as a bottle.

The barrel 4 of the pump is reciprocable into and out of the body 2 under the influence of a claw-grip 10 which is at the root of a nozzle 5. The claw-grip has projections diagrammetrically opposed across the barrel of the pump so that is can be gripped simultaneously by the first and second fingers of the hand of the user in which the rear part of the body is fitted. By squeezing those two fingers and forcing the barrel 4 into the body a piston within that body sweeps through it and a measured does of material is ejected from the nozzle 5.

In the drawings, the nozzle is shown fitted with a plug 5a which is provided to prevent contamination when the pump is not actually in use.

Looking now in more detail at the pump, Fig. 2 shows how the skirt 6a of the body has inserted into it a cap 6 the internal diameter and screw threading (or other attachment means of which) is compatible with the intended container to which the pump is to be attached. In a coaxial channel extending downwardly from the roof of the body, there is received a spring 9 and ball 8, and a tubular projection from the centre of the cap 6 is used to entrap and seat the ball 8 against the loading of the spring thereby forming a one-way valve. A radial port 9a leads from the channel to the main cylinder part of the body.

The tubular projection of the cap is continued also downwardly and can receive suction tube 7 for reaching towards the bottom of the container. The dispenser pump can also be used in an inverted attitude and in this case the tube 7 will not be fitted.

As is more clearly seen in Fig. 3, the cap 6 also has an off-centre orifice 11 in its roof, which is at the end of a groove 1 2 which extends to the end of the cap and then down that edge, interrupting as it does so the ribs with which the cap forms a snap fit with the skirt 6a. Adjacent to this orifice is a ledge 1 2a which over a short portion of the length of the groove 1 2 almost obstructs it. At the foot of the groove, an outwardly projecting lug 1 3 is provided which is to register with a corresponding notch in the edge of the skirt 6a.

Above the lug 13, a narrow channel 1 4 allows air communication from the groove 1 2 to the outside of the skirt and thus means is provided for ingress of air of compensate for materal lost from the container in such a way however that, due to the viscosity of the material to be dispensed and the narrowness and convoluted nature of the channel, and especially due to the restriction due to the ledge 1 2a which will pass gas but effectively not liquid, risk of loss of material even when the container and pump are inverted is minimal.

The cylinder of the pump is formed within the main body 2 by an insert 2a which is snap fitted into the projecting flange of fthe main body. Previously, the barrel 4 and its integral cup washer piston 3 have been fitted through a flanged orifice in the end of the insert 2a, and a conical spring 20 engages against the end of the barrel inside that piston and onto the end wall of the cylinder. By adjustment of the length of the barred fitted and in particular by adjustment of the position of the abutment 4a where the barrel meets the flange of the orifice, the stroke and therefore the displacement of the pump may be fixed, and a range of different displacement provided for a pump which is externall identical.

To hold the barrel within the insert 2a, the nozzle 5 together with its integral claws 10 is snap fitted onto the end of the barrel, trapping thereby a second ball 8 against a frusto conical seating formed within the stem and pressed by a spring 9 to engage on that seating. As already mentioned a plug 5a will normally be fitted to the end of the nozzle when the pump is not in use so as to prevent ingress of contaminants. Furthermore, the annular ridges used to provide a snap fitting for the plug may be used for the retention of an extension tube for dispensing, which is some cases may be desirable.

As has been mentioned, it is possible to use the dispenser pump in an inverted attitude, with the tube 7 omitted. Using the dispenser pump in an inverted attitude has the advantage that it is possible to use all the liquid or semi-liquid material in the container (not shown) secured to cap 6. This is because the bottom of the liquid is in direct communication with the valve formed by ball 8. There is no possibility of wastage of the material in the container as may occur if the the tube 7 does not extend to the bottom of the container.

Furthermore, if the liquid or semi-liquid material in the container is viscous, use of the dispenser pump in an inverted attitude enables the delivery of the material to the pump to be assisted by gravity. Since the material does not have to be lifted the length of the tube 7, the action of the dispenser pump is speeded up.

However, if the dispenser pump shown in Figs. 1 to 3 is used in the inverted attitude, problems may arise. In particular, since the material in the container is in direct contact with the orifice 11, the surface tension of the liquid or semi-liquid material across the orifice 11 creates a resistance to the passage of air through groove 1 2 and orifice 11 to the container. As the air does not enter freely in the container, withdrawal of material causes a partial vacuum to form in the container. As this partial vacuum increases, it becomes more difficult to remove material from the container and a smaller dose of material is delivered.

Also, when dispensing viscous liquids, bubbles of air in the container from orifice 11 rise slowly through the liquid. In the dispenser pump of Figs 1 to 3 these bubbles pass close to the entrance to the valve formed by ball 8.

If such bubbles are passing the entrance when the dispenser pump is operated, it is possible for a mixture of air and liquid to be drawn into the dispenser pump, thereby causing a smaller dose of material to be delivered.

To overcome this problem, it is possible to provide a guide for air from orifice 11.

As shown in Fig. 4, a dispenser pump generally similar to that of Figs. 1 to 3 is used except that tube 7 is omitted. An air guide 20 is provided around the inlet 21 to the valve formed by ball 8. The guide 20 comprises a body 22 which is secured to the inlet 21 by pipe 23. The pipe 23 forms the passage for material from a container (not shown) secured by cap 6 to the dispenser pump. The body 22 is hollow and forms an annular cavity 24 around the inlet 21. This cavity is open at its end nearest the dispenser pump and communicates with orifice 11. To prevent ingress of material from the container to the cavity 24, the body 22 is secured to the upper surface 25 of the cap 6 by a flange 26. A tube 27 extends from the cavity 24 into the container.

The bore of the tube 27 is wider than the orifice 11 and this reduces the resistance effect of the surface tension of the liquid. This enables air to enter the container more rapidly. This is assisted by the effect of the volume of air within cavity 24. The tube 27 separates the entrance of the air into the container from the exit of liquid through inlet 21 and furthermore the movement of air is away from inlet 21 rather than towards it when the dispenser pump of Figs. 1 to 3 is used in an inverted attitude. Thus the possibility of air being drawn into the dispenser pump is substantially reduced.

Although the orifice 11 and the tube 27 are shown on opposite sides of the body 20 in Fig. 4, this is not necessary and the tube 27 may be at any position around the inlet 21.

Claims (11)

1. A dispenser pump having a body in which a piston works reciprocably for dispensing material from an output nozzle of the pump and a discrete cap secured to the body, the cap being for attaching the pump to a container of material to be dispensed, there being an air passage defined between the body and the cap and extending from the outside to the body to inside of the cap.

2. A dispenser pump according to Claim 1, wherein the air passage opens to the outside of the body through a gap between the body and the cap.

3. A dispenser pump according to Claim 1 or Claim 2, wherein the air passage is elongate and narrow, extending from adjacent the mouth of a cup-like cap to an orifice in the base of the cup-like cap.

4. A dispenser pump according to Claim 3, wherein the passage is provided by a groove in the outer surface of the cap.

5. A dispenser pump according to Claim 3 or Claim 4, wherein there is adjacent the orifice in the cap a local restriction in the air passage forming a barrier to the passage of liquid.

6. A dispenser pump according to any one of the preceding Claims, wherein the cap and body are snap-fitted together.

7. A dispenser pump according to Claim 6, wherein the cap includes an inlet nozzle for material to pass into the body of the pump, the end of the nozzle innermost in the body being a seat for a unidirectional inlet valve of the pump.

8. A dispenser pump according to Claim 7 which additionally has a unidirectional outlet valve.

9. A dispenser pump according to any one of the preceding claims, wherein there is additionally provided an air guide within the cap and in communication with the air passage, an air outlet of the air guide being substantially wider than the air outlet of the air passage into the cap.

10. A dispenser pump according to Claim 9, wherein the air guide forms a plenum around an inlet for material into the body of the pump and its air outlet is a tube extending to the side of that inlet and axially away from it.

11. A dispenser pump according to Claim 9 or Claim 10 wherein the air guide is positioned by a central tube fitting within an or the inlet for material into the body.

1 2. A dispenser pump substantially as herein described with reference to and as illustrated in Figs. 1 to 3 or Fig. 4 of the accompanying drawings.