Tap for a liquid container

Abstract

 The tap has a hollow cylindrical body (12) closed by a diaphragm (14) at one end and having a radial outlet (16). A valve closure member (30) is axially movable by pressure on the diaphragm through a mechanism (60) to lift a closure flange (38) off a seat (20). An annular passage (40) is defined between the body wall and a cylindrical wall (35) of the valve closure member to provide laminar flow from the valve seat to the outlet. A conical end (36) of the valve closure member faces the flow of liquid and is surrounded by a frusto-conical wall (53) to define a divergent annular chamber (54) of uniform cross-section leading to the annular passage (40). This chamber reduces in cross-sectional area as the tap is opened. This combination of features substantially prevents swirling and turbulence and permits dispensing of carbonated liquids without loss of carbonation.

Description

[0001] This invention relates to a tap for a liquid container and is concerned with dispensing liquids from pressurised containers, e.g. for dispensing carbonated drinks.

[0002] It has been usual for carbonated drinks to be sold in glass bottles with screw-on caps, but these are being supplanted by PET containers. The use of PET enables much larger containers to be produced economically and the material is sufficiently strong to permit increased carbonisation for these larger containers.

[0003] With the use of larger containers, it is desirable for a tap to be fitted on the container to permit the liquid to be easily dispensed when required. It is desirable for the tap to include a valve which is linearly movable between open and closed positions, since such taps can be cheaply made and are particularly convenient to operate. Such taps are used for dispensing wine from "bag-in-box" containers, for example, and this type of valve is disclosed in GB-A-977660, AU-A-403943 and GB-A-214032.

[0004] These known valves can be used for dispensing carbonated drinks, but there is a problem that poured drinks tend to be flat due to loss of carbonation during the dispensing operation.

[0005] It is known to provide flow restrictors for the purpose of controlling flow of carbonated liquids by inserting the restrictor in a flow line. Such a restrictor for a beer line is known from GB-A-2117094. The restrictor serves to reduce flow, so as to reduce turbulence at an outlet tap. If turbulence is too great, the restrictor is further closed to restrict flow.

[0006] The restrictor has a frusto-conical body which is received in a complementary bore. The body has a conical head whose cone angle is smaller than that of the body and the apex of the cone faces the liquid flow. The conical head, therefore, directs liquid to a shallow annular passage around the body.

[0007] The flow is reduced by moving the restrictor in opposition to the liquid flow, so that the annular passage is reduced in depth.

[0008] If the restrictor was to be used as a valve closure member (which is not suggested in this document) then, as the valve closure member was moved to the open position, the annular passage around the valve body would gradually increase and control of flow would be totally lost. If flow is too high, then turbulence occurs at the outlet and, if flow is too restricted, then there is a sudden expansion as the liquid leaves the constricted area, resulting in both cases in loss of carbonation. Furthermore, the valve would be substantially complicated in construction. The type of valve with which the invention is concerned, requires the valve closure member to be biased closed in the direction of flow. Bias in the reverse direction means that exceptionally high bias is required to resist the pressurised liquid and prevent leakage and this cannot be provided by a simple diaphragm.

[0009] GB-A-977660 discloses a conical end to a guide rod for a valve closure member. The conical end directs flow to an annular passage around the guide rod. The passage opens into a large chamber at the inlet side of the valve closure member. The arrangement is, therefore, totally unsuitable for carbonated liquid, due to the expansion at the chamber.

[0010] GB-A-2049106 is concerned with a tap for carbonated liquids. The tap provides no control for flow of liquid at the inlet side of the valve closure member. The liquid is caused to flow past angular edges at the valve seat and control of flow is exercised at the outlet side of the valve seat. This control is exercised by opening up a smoothly divergent annular portion which opens into a spout. This solution requires a complex valve structure with numerous seals, which would be expensive to produce.

[0011] It is possible to envisage reversing the operation of the valve and flowing carbonated liquid into the outlet. This would mean, however, that the closure bias was acting against the liquid pressure with the resultant problem previously referred to. In addition, this would means that, as the valve was opened, there would be an enlarging chamber between the inlet and the annular passage around the valve closure member causing uneven flow and turbulence.

[0012] The present invention avoids all of these problems.

[0013] In accordance with this invention, there is provided a tap for a liquid container, comprising a hollow body having an inlet end, a closed opposite end and an outlet opening between the ends, a valve seat within the body, a valve closure member biased into engagement with the valve seat to close the inlet end from the outlet opening, means actuable to lift the valve closure member off the seat to open the tap, wherein an annular passage of substantially constant cross-sectional area is defined around the valve closure member between the seat and the outlet opening, the cross-sectional area remaining substantially constant as the valve closure member is moved from closed to open positions, the valve closure member has a conical surface divergent from an apex to the annular passage, the apex facing the inlet end, and the inlet end is provided with a frusto-conical portion defining a inlet opening, and surrounding the conical portion to define an annular passage therewith, the annular passage reducing in cross-sectional area as the valve closure member moves in the opening direction.

[0014] This arrangement permits the valve to be cheaply constructed with a smooth non-turbulent flow in operation. As the valve closure member moves in the opening direction, the annular passage maintains a controlled laminar flow and the flow to the valve seat is increasingly restricted, ensuring that there is no sudden surge of liquid, with resultant loss of carbonation.

[0015] Reference is now made to the accompanying drawing, wherein:-

Figure 1 is a sectional view of a tap according to the invention; and

Figure 2 is a side elevation of the tap viewed at 90° displacement from the view of Figure 1.

[0016] The tap shown comprises a screw-threaded cap 11 for screwing on a bottle neck 10. The cap is integrally moulded from plastics material with a cylindrical body 12 having an inlet end 13 and an integral domed diaphragm 14 closing the opposite end. An outlet opening 15 is provided in the peripheral wall of the body adjacent the diaphragm and an outlet spout 16 communicates with the outlet opening. A valve stem 17 projects axially into the body from a concave inner surface of the diaphragm and is integrally moulded with the diaphragm. A frusto-­conical shoulder is formed in the body interior and defines a valve seat 20.

[0017] A valve closure member 30 is a single plastics moulding and includes a socket portion 31 which has formations 32 permitting snap-engagement of the socket portion on the stem. An annular flange 33 extends from the socket portion 31 adjacent the diaphragm 14 and has a convex surface facing and shaped complementary to the concave surface of the diaphragm. The member has a conical end 36 converging to an apex 37 facing the inlet end of the body. A cylindrical wall 35 encircles the socket portion and joins this conical end to the flange 33. An outwardly projecting flexible annular closure flange 38 of the member co-operates with the valve seat 20 and is urged to seal against the seat by the diaphragm 14.

[0018] In use the domed diaphragm is depressed (as described hereafter) so as to move the valve closure member linearly to lift the member off the seat 20 against the bias of the diaphragm. In this open position, a shallow depth annular passage 40 of uniform cross-section carries liquid from the valve seat to the outlet opening 15.

[0019] A separately moulded body piece 50 is attached to the main body 12 and comprises an axial inlet tube 51 leading to an inlet opening 52 at the apex of a conical wall 53. The conical wall has the same cone angle as the conical end 36 and is complementary to it, so that an annular chamber 54 of constant cross-section is defined between the conical wall and the conical end. The cone angles may be slightly different, so that the cross-­sectional area of the chamber 54 reduces towards the valve seat.

[0020] The inlet tube 51 may extend at an acute angle to the axis of the tap in the same direction as the outlet spout 16 to allow a container to be substantially emptied without the necessity for manual tilting of the container.

[0021] The arrangement permits smooth flow of liquid from the inlet tube to the valve seat, the conical form of the chamber 54 reducing the risk of turbulence. Beyond the valve seat, the shallow annular passage 40 permits laminar flow of the liquid to the spout 16 and there is no possibility of sudden expansion or excessive swirling causing turbulence, so that there is little carbon dioxide loss from solution. The chamber 54 reduces in cross-sectional area as the valve is opened, so that any sudden rush of liquid is prevented.

[0022] The actuating mechanism 60 is identical with that disclosed in GB-A-2140132. The mechanism is integrally moulded with the body and diaphragm and comprises a pair of divergent levers 61, 62 hinged to the body by integral hinges 63, 64. Gussets 65, 66 connect the levers to the diaphragm 14 and to spring biasing member 67 also integrally formed with the diaphragm. In use, the levers are squeezed together against the resilience of the biasing member 67 to deflect the diaphragm 14 and thereby lift the valve closure member off its seat. This actuating mechanism is fully described in GB-A-2140132.

Claims

1. A tap for a liquid container, comprising a hollow body (12) having an inlet end (13), a closed opposite end (14) and an outlet opening (15) between the ends, a valve seat (20) within the body, a valve closure member (30) biased into engagement with the valve seat to close the inlet end from the outlet opening, means (60) actuable to lift the valve closure member off the seat to open the tap, characterised in that an annular passage (40) of substantially constant cross-sectional area is defined around the valve closure member (30) between the seat (20) and the outlet opening (15), the cross-sectional area remaining substantially constant as the valve closure member is moved from closed to open positions, the valve closure member (30) has a conical surface (36) divergent from an apex (37) to the annular passage, the apex facing the inlet end (13), and the inlet end is provided with a frusto-conical portion (53) defining an inlet opening (52), and surrounding the conical surface (36) to define an annular passage (54) therewith, the annular passage reducing in cross-sectional area as the valve closure member moves in the opening direction.

2. A tap according to Claim 1, wherein the cone angle of the frusto-conical portion (53) is substantially the same as the cone angle of the conical surface (36).

3. A tap according to Claim 1 or 2, wherein an inlet tube (51) leads to the inlet opening (52).

4. A tap according to Claim 3, wherein the inlet tube (51) has the same diameter as the inlet opening (52).

5. A tap according to any preceding claim, wherein the closed end of the body defines a diaphragm (14) which biases the valve closure member (30) against the seat (20), the diaphragm having a domed configuration with a concave inner surface and the valve closure member (30) having a complementary convex surface adjacent to and facing the concave surface.

6. A tap according to any preceding claim, wherein the valve closure member (30) has an outwardly projecting flexible annular flange (38) which engages with the valve seat (20).

Drawing