Technical Field

This invention relates to the dispensing of doses of fluid material from a body of fluid material held in a container using a dose dispenser located in the outlet of the container.

Description of Prior Art

The simplest form of dose dispenser uses the cap of the container as a dose measure. The potential for spillage and the relative inaccuracy of this method has led to a search for alternative methods. In one of these, an open- topped measuring cup is moulded in the neck of a flexible- walled bottle and is filled with liquid from the bottle through a dip tube which opens into the cup below its rim. The bottle is squeezed in an upright position to express liquid into the cup in an amount in excess of the desired dose. The squeezing pressure is then released whereupon liquid in the cup above the dip tube outlet is sucked back into the tube. The measured dose of liquid is then poured out of the cup.

In WO 92/10729 there is described an improved dose dispenser in which a piston device can move within a dosing chamber in response to increased fluid pressure within the container to which the dose dispenser is fitted. The dosing chamber is filled by inversion of the container and then the piston device is caused to move outwards along the dosing chamber by squeezing the flexible wall of the container. This outward movement of the piston device successively alters the open/closed configuration of the inlet and outlet of the dosing chamber from inlet open/outlet closed (dose filling) through inlet closed/outlet closed (dose measuring) to inlet closed/outlet open (dose dispensing) .

Further development has now produced a new, improved design of dose dispenser which gives a more positive action in use and which facilitates manufacture and assembly.

Summary of the Invention

According to this invention, a dose dispenser for location in the outlet of a container of fluid material from which a dose of fluid material is to be dispensed is characterised by a dosing chamber comprising a wall defining an internal volume and having spaced outlet and inlet ends defining respectively an outlet through which a dose of fluid material can be dispensed and an inlet through which fluid material may pass into the chamber from the container, a piston head moveable within the dosing chamber between the inlet end and the outlet end and dividing its internal volume into separated forward and rear volumes on opposite sides of the piston head of which the relative volumetric proportions change as the piston head moves within the dosing chamber, the piston head being moveable between a first position at the inlet end through a second position approaching the outlet end to a third position at the outlet end at which third position the rear volume of the dosing chamber is opened to the outlet, and an inlet closure member which leaves the inlet open to the rear volume of the dosing chamber as the piston head moves from the first position towards the second position and closes the inlet when the piston head is in the second and third positions.

For multi-dose dispensing, the piston head of the dose dispenser is reciprocally moveable between the first and third positions.

The wall of the dosing chamber preferably is cylindrical, with a circular cross-section preferred ^' . The movement of the piston head between the first, second and third positions is then axial of the cylindrical wall.

The piston head may be supported on an elongate member which extends through the inlet without closing it. The elongate member may be, for example, of cruciform cross- section compared with an inlet of circular cross-section. The inlet closure member also may be supported on this elongate member but spaced from the piston head and located externally of the dosing chamber when the piston head is in the first position. The piston head and the inlet closure member may be spaced by a distance such that the inlet closure member moves into engagement with the inlet to close it as the piston head moves into the second position.

Further movement of the piston head from the second to the third position may be permitted by having the inlet closure member engage with the inlet to close it as a sliding engagement in the direction of movement of the piston head. Thus, the inlet may be defined by a wall, for example a cylindrical wall, and the inlet closure member may enter the inlet and close it by sliding engagement with the wall of the inlet. The elongate member may also slidingly engage the wall of the inlet whilst the piston head moves from the first position to the second position to maintain alignment of the elongate member in the direction of that movement.

The piston head separates the forward and rear volumes within the dosing chamber during a dispensing operation. It is preferred, when the piston head is in the first position, that it also engages the inlet of the dosing chamber to close it. This allows the provision of a seal against leakage of the fluid material from the container.

Movement, of the piston head from the first position through the second position to the third position, may be in response to increased fluid pressure induced within the container to which the dose dispenser is fitted. The piston head may have a rear surface i.e. the surface facing

towards the rear volume of the dosing chamber, against which the increased fluid pressure within the container can be applied to cause the specified movement of the piston head.

The invention includes a dose dispenser and container combination in which the dose dispenser is located in the outlet of a container for fluid material. In a preferred arrangement, the dose dispenser is a snap fit and/or a friction fit within the outlet of the container. It is also possible to make the dosing chamber of the dose dispenser an integral moulding with the outlet of the container, for example as part of the neck finish of a bottle, if this is desired.

The container preferably has a flexible wall, for example of plastics material, so that an increase in fluid pressure within the container can be induced by squeezing the flexible wall of the container. The container may be a thermoplastic moulding, for example a polyester bottle.

The outlet of the dosing chamber may be defined by the wall of the dosing chamber being cut-away in part at its outlet end. This allows the piston head to be retained in contact with the remaining part of the wall at the outlet end when it is in the third position whilst the rear volume of the dosing chamber is opened to the outlet. A suitable arrangement is provided by the outlet end having a castellated shape.

At the outlet end, the wall of the dosing chamber may be surrounded by an outer wall having a first part which is opposite to and spaced from the outlet and a second part which is joined to the wall of the dosing chamber. This outer wall allows the provision of a continuous pouring lip in case the cut-away outlet end of the dosing chamber makes pouring difficult. It also allows the provision of a rebated portion where it joins the wall of the dosing chamber to provide accurate location of the dose dispenser

in the outlet of a container.

The dose dispenser and container combination of the invention may also include a closure cap for the container outlet.

Blow-moulded containers are normally made from a moulded preform incorporating a first portion which will be the outlet of the container, for example in the form of a tubular neck, and an integral second portion. This second portion is expanded by a blow-moulding step to form the body of the container integrally attached to the preformed outlet. In moulding the preform, for example by injection moulding, the first portion, which will become the outlet of the container may be moulded so that the dosing chamber of the dose-dispenser according to the invention is moulded as an integral part of this first portion.

The piston head, elongate member and inlet closure member of the dose dispenser may be a one piece moulding which is inserted into the dosing chamber. This applies whether the latter is moulded integrally with the outlet of the container or is a separate item. For ease of filling, such insertion may be carried out after the container has been filled with the fluid to be dispensed, but prior to the fitting of a closure cap.

The invention further includes a method of dispensing a dose of fluid material from a body of fluid material held within a container of a dose dispenser and container combination according to the invention in which the container has a flexible wall, preferably of plastics material, which can be squeezed to induce increased internal fluid pressure within the container characterised by inverting the container, squeezing the flexible wall of the container to induce increased fluid pressure within the container and thereby to move the piston head sequentially from the first position through the second position to the

third position so that in that sequence fluid material flows through the inlet to fill the expanding rear volume of the dosing chamber as the piston head moves from the first position to the second position which flow is stopped when the inlet is closed by the inlet closure member so that a measured dose of fluid material is contained in the enclosed rear volume of the dosing chamber and when the piston head moves into the third position, the measured dose of fluid material runs out of the rear volume of the dosing chamber through the outlet and is thereby dispensed.

When the piston head of the dose dispenser is reciprocally moveable between the first and third positions to allow multi-dose dispensing, then release of the flexible wall of the container from squeezing will cause a reduction of fluid pressure within the container which will cause the piston head to return from the third position to the first position. The dose dispenser is then ready for the dispensing of a further dose.

Liquids are the preferred fluid materials for dispensing using the dose dispenser of the invention.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:-

Brief Description of the Drawings

Figure 1 is a schematic section in elevation of a dose dispenser according to the invention located in the outlet neck of an upright flexible-walled bottle (shown in part only) containing a liquid to be dispensed and showing the piston head in the first position;

Figure 2 shows the same section as Figure 1 but with the bottle cap removed and the bottle inverted at an angle and squeezed to force the piston head towards the outlet

under the induced increase in internal fluid pressure;

Figure 3 shows the same section as Figure 2 in which the piston head has moved to the second position to define a measured dose of liquid;

Figure 4 shows the same section as Figure 3 in which the piston head has moved to the third position and the measured dose of liquid is being dispensed; and

Figure 5 is a cross-section on the line V....V in Figure 1 showing the cross-sectional shape of the elongate member.

Description of Preferred Embodiment

Referring to Figure 1, a bottle 1 (shown in part only) has a flexible wall 2 and a cylindrical neck 3 which defines an outlet 4 and which has an external screw thread 5 for securing an internally-threaded closure cap 6 (shown in dotted outline) .

A dose dispenser 7 comprises a dosing chamber 8 having a cylindrical wall 9 which is located as a close friction fit within the neck 3 of the bottle 1. The dosing chamber 8 has an inlet end 10 which is located within the neck 3 of the bottle 1 and projects towards the interior of the bottle 1. The inlet 11 of the dosing chamber 8 is defined by a cylindrical wall 12 which is coaxial with the wall 9 of the dosing chamber 8 and of reduced diameter compared with the wall 9.

The outlet end 13 of the dosing chamber 8 projects out of the neck 3 of the bottle 1. It is open-ended and of castellated form so that the cut-away parts between the c ^' astellations 14 comprise an outlet 15.

An outer wall 16 surrounds and is spaced from the wall

9 at the outlet end and is joined to that wall 9 at its lower end 17. This outer wall 16 provides a continuous pouring lip 18 and a rebate 19 at the lower end 17 which seats on a top surface 20 of the neck 3 of the bottle 1 and locates the dose dispenser 7 in the desired position.

A piston head 21 comprises a circular disc part 22 surmounting a frusto-conical part 23 of lesser diameter having a peripheral surface 24. The disc part 22 of the piston head 21 has a forward surface 25, a rear surface 26 and a peripheral edge 27. This edge slides along the internal surface of the cylindrical wall 9 of the dosing chamber 8 and divides the dosing chamber 8 into a rear volume 28 and a forward volume 29. It is not necessary for the edge 27 to engage the internal surface of the cylindrical wall 9 as a fit which is a liquid-tight seal although it can be so for critical applications. In most cases, the speed at which the dose dispenser of the invention operates means that any liquid seepage across the piston head is minimal and has no significance for dose accuracy.

The peripheral surface 24 of the frusto-conical part 23 of the piston head 21 seats in a mating chamfered surface 30 in the wall 12 of the inlet 11 when the piston head is in the first position shown in Figure 1.

The piston head 21 is supported on an elongate member 31 having four limbs 32 which give the member 31 a cruciform cross-section. The outer edges 33 of the limbs 32 engage the inner surface of the wall 12 of the inlet in a sliding fit.

-_α inlet.closure member 34 is supported on the opposite end of the elongate member 31 and has a cylindrical wall 35 giving it the shape of an inverted cup. The outer surface of the cylindrical wall 35 is dimensioned to make it a sliding fit within the inner surface of the wall 12 of the

inlet 11. Four cut-outs 36 in the wall 35 impart a degree of springiness which facilitates assembly. A chamfered external bead 37 at the end of the wall 35 butts against an internal chamfer 38 at the end of the wall 12 of the inlet 11 when the inlet closure member 34 fully enters the inlet 11 and prevents further movement of the piston head 21 beyond the third position as shown in Figure 4.

The closure cap 6 has an axial tubular spigot 39 of which the open end 40 seats against the forward surface 25 of the piston head 21 when the cap 6 is fully screwed onto the neck 3 of the bottle 1. This pushes the piston head 21 down so that the mating surfaces 24 and 30 are pressed together to form a fluid-tight seal.

After inversion of the bottle 1 (e.g. at the angle shown in Figure 2) and squeezing of its flexible wall 2, the increased fluid pressure thereby induced within the bottle

1 is exerted on the rear surface 26 of the piston head 21.

The piston head 21 is pushed along the dosing chamber 8 as shown, opening the inlet 11 and allowing fluid material (in this case the liquid 41) within the bottle 1 to flow into the rear volume 28 of the dosing chamber 8. As the piston head 21 moves along the dosing chamber 8, the rear volume 28 increases in volume proportionally to the decrease in volume of the forward volume 29 of the dosing chamber 8 and so is filled with a progressively increasing volume of liquid 41.

Movement of the piston head 21 continues along the dosing chamber 8 until the piston head 21 reaches the second position as shown in Figure 3 when the inlet closure member 34 engages the wall 12 of the inlet 11 to close it. With the piston head in the second position, no further liquid 41 can flow into the dosing chamber 8 and so the volume of liquid 41 in the rear volume 28 of the dosing chamber 8 is the measured dose tc be dispensed.

Figure 4 shows the completion of the outward movement

of the piston head 21 when in the third position, further outward movement being prevented by abutment of the chamfered bead 37 on the inlet closure member 34 against the chamfered surface 38 at the end of the wall 12 of the inlet 11. In the third position, as shown, the piston head 21 has moved along the castellations 14 of the outlet end 13 of the dosing chamber 8 so as to expose the outlet 15 to the rear volume 28 of the dosing chamber 8 and allow the measured dose of liquid 41 to flow out over the pouring lip 18 of the outer wall 16 and be dispensed.

When the flexible wall 2 of the bottle 1 is released from the squeezing pressure, the resulting reduction in internal fluid pressure within the bottle 1 to below atmospheric pressure causes the piston head 21 to be drawn back into the first position. A further measured dose of liquid 41 may then be dispensed by a repeat procedure if desired. Alternatively, the closure cap 6 may be screwed back onto the bottle 1 before it is returned to storage.

The dosing chamber 8 is preferably a one-piece plastics moulding. Polypropylene is a suitable material, The piston head 21, the elongate member 31 and the inlet closure member 34 are also preferably a one-piece plastics moulding.

Polypropylene is, again, a suitable material.