LIQUID DOSING DEVICES

Abstract

A dosing device is described, for dispensing doses of liquid from a container. It has an outlet passage with a front outlet tube (44) and a control chamber (2,29) positioned behind the front outlet tube. A flow path for dosed flow of liquid squeezed from the container leads in around the front of the control chamber (2,29) to the outlet tube (44), via flow openings (23). The control chamber (2) has control openings (28) to admit a restricted flow and time the fall of a blocking piston (3) to a blocking position where it blocks the outlet passage to terminate a dose. To improve uniformity of dosing, the outlet tube (44) has a tortuous flow-restricting formation (449) formed by a set of inward radial finger projections (49).

Claims

1. A dosing device for dispensing doses of liquid from a container, the device defining an outlet passage with a front discharge opening and having a control chamber component defining a control chamber behind the front discharge opening, a flow path leading from past or around the control chamber component to the outlet passage by way of one or more flow openings adjacent the front of the control chamber, the control chamber component having one or more control openings to admit a restricted flow of liquid into the control chamber from a container for said liquid on which the device is provided in use, and an obturator in the control chamber which is movable in the control chamber to a blocking position where it blocks the outlet passage to terminate a dose; wherein the outlet passage has a tortuous flow-restricting formation.

2. A dosing device according to claim 1 in which the tortuous formation comprises a plurality of inward projections from a wall of the outlet passage.

3. A dosing device according to claim 2 in which the tortuous formation comprises a set of radial finger projections extending from the wall of the outlet passage to at or adjacent a centre thereof.

4. A dosing device according to claim 1 in which the tortuous formation comprises a plurality of spaced elongate elements defining plural subsidiary flow passages between them.

5. A dosing device according to claim 2, in which the outlet passage is provided as an outlet tube with a straight tube portion leading to the front discharge opening, and the tortuous formation is in the straight tube portion.

6. A dosing device according to claim 5 in which the tortuous formation is localised in the outlet tube, with open flow cross-sections of the tube before and after the tortuous formation.

7. A dosing device according to claim 5 in which the straight outlet tube portion is generally cylindrical.

8. A dosing device according to claim 1 in which the tortuous formation is comprised in a moulded component in one piece with the outlet passage.

9. A dosing device according to claim 1 comprising a dump valve arrangement at the back of the control chamber to allow liquid to escape from the control chamber behind the obturator.

10. A dosing device according to claim 9 in which the dump valve comprises a dump valve seat and a dump valve member which make a convergent guiding engagement with one another, the dump valve member entering the dump valve seat to make a seal in a closed condition of the dump valve.

11. A dosing device according to claim 10 in which the dump valve member is a ball.

12. A dosing device according to claim 1 comprising a front cap component through which the outlet passage and discharge opening are centrally defined, and providing a rearwardly-projecting tubular extension of the outlet passage presenting a seat for the obturator to rest against in the blocking position.

13. A dosing device according to claim 1 in which the tortuous formation is downstream of where the outlet passage is blocked by the obturator.

14. A dosing device according to claim 1 in which the outlet path for liquid leads forwardly outside the control chamber component and then radially inwardly, by way of said flow opening(s), around or through the front of a wall of the control chamber component to the outlet passage which is central.

15. A dosing device according to claim 1 in which the obturator is a piston slidable in the control chamber.

16. A dosing dispenser comprising a dosing device according to claim 1 mounted on a container.

17. A dosing dispenser according to claim 16 in which the container is resiliently squeezable.

18. A dosing dispenser according to claim 16 in which the container contains a said liquid to be dispensed and the viscosity of the liquid at room temperature (25 C.) is more than 10 mPa.Math.s and less than 100 mPa.Math.s.

19. A dosing dispenser according to claim 18 in which the liquid is a detergent liquid.

Description

[0034] First, the general features and principles of an embodiment of a dispenser of the kind described are described with reference to FIGS. 1 and 2 which show a prior art dosing device 100 as disclosed in WO2005/049477. The dosing dispenser device 100 is designed to fit onto the open neck of a plastic container 10, indicated in broken lines in FIG. 2. It has a front cap component 400 which is a one-piece moulding comprising a front plate 420, a central outlet tube 440 with a forwardly projecting nozzle 4410, an outer securing skirt 410 having a securing formation 4110 by which it fixes onto the container neck 10, and a cover cap 450. The cover cap joins to the rest of the cap component 400 through an integral butterfly hinge 460 so that the cap 450 tends towards being either shut or fully open.

[0035] The underside of the cap 450 has an integral nozzle plug 4510 which plugs the nozzle 4410 when the lid is shut.

[0036] The second major component of the device is a control chamber or insert cylinder component 200, sometimes called a timing chamber. This component consists essentially of a closed cylindrical sidewall 250 defining internally a control chamber 290, and having around its front edge a connection structure in the form of an integral forward extension 210, meeting the cylinder sidewall 250 and having a front fixing lip 220 which snaps into the cap skirt 410 (FIG. 2).

[0037] Three equidistantly-spaced flow openings 230 are provided through the forward extension 210.

[0038] Behind the front plate 420 of the cap 400 the central cylindrical outlet tube 440 projects back into the open front end of the control chamber 290.

[0039] The described cap and insert are preferably of polypropylene, but other materials are possible.

[0040] An obturator or blocking piston 300 is enclosed in the control chamber 290, and has a flat central disc 310 with a set of axially-projecting integrally-formed peripheral guide lugs around its edge. The control piston 300 fits substantiallyi.e. occupying nearly all the cross-section but as a loose fitinto the control chamber 290 so as to be freely slidable in it, between a forward position in which its central web surface 310 lies against and blocks the rear entrance to the outlet tube 440, and a rear position in which it lies against the rear wall 260 of the chamber 200.

[0041] An outlet passage for liquid in the container therefore exists, as indicated by arrow B, from the container's interior space 110 forward through the radial clearance between the chamber component 200 and container neck 10, forward and in through the flow openings 230 to the space between cap 400 and chamber 290 (and in front of the control piston 300), in and forward through the rearward extension of the outlet tube 440 and out through the discharge nozzle 4410.

[0042] The rear wall 260 of the control chamber component 200 features a central discharge or dump opening 270 surrounded by a convergent valve seat 263. Small discrete control openings or timer openings 280, in this case three openings spaced equidistantly, penetrate the rear wall towards its edge.

[0043] A retaining cage 500 is snap-fitted onto the centre of the rear wall 260. In this cage a plastic valve ball 600 is retained. The ball 600 cannot escape from the cage but when it lies against the cage back plate, as in FIG. 2, there is a substantial clearance for flow out of the control chamber 290 through the dump opening 270, around the ball and away through the cage windows into the container interior 110. When the ball 600 lies in a forward position however its guided engagement in the convergent seat 263 completely seals the dump opening 270 and the only communication between the container interior 110 and the control chamber 290 is through the small control openings 280.

[0044] Normally the container stands upright with the device 100 facing upwardly as shown. To dispense a dose the container is upturned and squeezed. Liquid flows out to the discharge nozzle along the outlet path (arrow B). At the same time the valve ball 600 moves forward, urged by gravity and the forward movement of liquid in the container, so that it blocks the dump opening 270. Liquid nevertheless flows through the control openings 280 from the container interior into the control chamber 290 behind the control piston 300. At the beginning of the operation the control piston 300 is at the back of the chamber 290, and the initial rush of liquid along the outlet path B fills up the front part of the device (in front of the piston 300) tending to delay it, in particular preventing it from simply falling under gravity. However as liquid gradually enters the control chamber 290 under squeeze pressure through the restricted openings 280 the piston 300 moves forward, at a predetermined rate depending on the size of the openings 280, the viscosity of the liquid and the size of the outlet tube 440. Eventually its central web or plate 310 meets the rear circular edge 4430 of the outlet tube 440 and blocks the discharge passage, immediately stopping the flow and terminating the dose.

[0045] The container may then be turned upright and the squeeze released. Under the influences of gravity, the weight of liquid in the control chamber 290 and air inflow from suction as the squeeze is released, the dump valve ball 600 falls open and liquid flows out from the control chamber 290 back into the container. At the same time there is a flow of liquid from the front of the device back through the flow openings 230 into the container.

[0046] Where the squeezed container exerts a sufficiently powerful suction, it may be possible to open the dump valve and restore the control piston 300 to its rear position without having to bring the container upright; suck-back of product from the nozzle area may be achieved at the same time. If such powerful suction is available a further dose may be dispensed without having to bring the container upright, simply by squeezing the container again to shut the dump valve and re-initiate the control function.

[0047] Referring now to FIGS. 3 to 7, a dosing device 1 embodying the present invention as shown. The general operation of the device is in line with the operation of the prior art device described above, and analogous components are referred to by analogous reference numerals (reduced by 1000 or 100). In each figure the device is shown with the cover cap 4 open, and with the device separate from a container with which it is used. In the device shown the securing formations 411 comprise a screw thread on the inside of the cap instead of the snap rib of the prior art embodiment, but either may be used. The dosing device shown is used in conjunction with a squeezable container of a liquid product, such as a household detergent liquid of viscosity from 20 to 60 mPa.Math.s at 25 C. Details of the squeezable container and liquid product are not given further because they are well known to the skilled person.

[0048] In this embodiment the resilient downward tabs 5 forming a cage for the valve ball 6 are formed as part of the base or lower end 26 of the control chamber 2. The control openings or timing openings 28 can be seen in FIG. 7, which also shows one of the front flow openings 23 through which the outflowing liquid enters from the container interior to the interior of the dosing device in front of the blocking piston 3.

[0049] A distinctive feature of the device 1 is a tortuous flow-restricting formation 449 formed in the outlet tube 44, and shown in more detail in FIG. 5. As indicated in the sectional view of FIG. 6, this formation is conveniently formed in one piece with the outlet tube 44, as a moulding, and this moulding may either be inserted (bonded or moulded-on) in the cap component 4 as shown in FIG. 6, or may be moulded integrally with it.

[0050] Referring to FIG. 5, the formation comprises a set of finger projections 49, each projecting radially inwardly from the wall of the generally cylindrical outlet tube 44 towards its centre, and all at the same axial position, i.e. in one plane or layer. The finger projections 49 reach nearly to the centre of the flow path, defining between them a set of subsidiary flow openings 491. In the illustrated embodiment there are six fingers, but their number, dimensions and shape may be adjusted according to convenience of manufacture and on the viscosity of the liquid to be dispensed. The skilled person will appreciate that, by forcing an intricate flow path through the subsidiary passages 491, with a high specific surface, the formation 449 provides much greater flow resistance to a liquid of moderate viscosity than it does to a flow of air. We have found that with this modification, the speed and reliability of restoration of the blocking piston 3 after each dispensing stroke are markedly improved when compared with a dosing device in which the same restriction of cross-sectional flow area through the outlet is provided by a simple cylindrical outlet cross-section.