GB2175279A - Improvements in or relating to liquid dispensing devices - Google Patents

Abstract

A bottle dispenser comprises a reservoir (8) having aligned inlet and outlet openings (2,14) and an axially reciprocal elongate operating member (12,13) extending through the outlet opening for movement between first and second axial positions. In the first position (shown) the inlet (2) is in communication with the reservoir (8,58) and the outlet opening is closed by sealing means operating between the reservoir wall and the operating member (12,13) and in the second position the inlet is closed by one end (25) of the operating member and the reservoir communicates via a radial (43) and an axial (44) bore with the other end of the operating member, the sealing means (32) remaining interposed between the radial bore (43) and the reservoir (8,58) during movement of the operating member (12,13,62,63) until the inlet opening (2) is closed. The sealing means may include a lip seal 32 as shown, or a pair of O-rings in outlet 14 above and below passages 43. To permit viewing of the liquid level, the reservoir may have a transparent side wall with relatively inclined inner and outer surfaces so that light is refracted from the region of the inlet opening (2) in a direction to facilitate viewing, irrespective of the liquid level. <IMAGE>

Description

SPECIFICATION Improvements in or relating to liquid dispensing devices This invention relates to liquid dispensing devices of the kind which serve to deliver measured quantities of liquid from an inverted bottle in response to axial movement of an operating member.

The invention is particularly concerned with a liquid dispensing device including a reservoir and an operating member axially movable against the action of a spring from a rest position, in which the reservoir is in communication with the interior of the bottle through an inlet tube while communication between the reservoir and an outlet is cut off, and a second position in which communication between the reservoir and the interior of the bottle is cut off while the passage between the reservoir and the outlet is opened, wherein the final stage of said movement of said operating member to its second position also opens a valve to admit air into the reservoir and thus to allow the contents of the reservoir to pass through the passage to the outlet. Such a liquid dispensing device will be referred to hereinafter as a liquid dispensing device of the kind specified.

It is to be understood that in order to ensure that the quantity of liquid dispensed in response to a single stroke of the operating member is equal to the capacity of the reservoir, it is essential that liquid is prevented from passing from the bottle to the reservoir while the passage between the reservoir and the outlet is open. In order to ensure that communication between the interior of the bottle and the reservoir is cut off before the contents of the reservoir are allowed to pass through the passage to the outlet, it has been normal practice to provide a lost-motion device between the operating member and the valve member used to close communication between the interior of the bottle and the reservoir. To provide the required lost motion it has been normal to mount the valve member on a spigot slideable in an axial recess in the upper end of the operating member.A helical spring has also been included in the recess to urge the valve member upwardly. Sealing means have been provided on the valve member to cooperate with the lower end of the inlet tube. Thus, as the operating member is moved from s rest position to its second position, the first part of the stroke serves to open the passage between the reservoir and the outlet and to place the sealing means on the spring loaded valve member against the lower end of the inlet tube, while the remaining part of the stroke opens the air valve and causes the valve member to be pushed by its spring against the lower end of the inlet member as the spigot on which it is mounted moves against the action of the spring into the interior of the operating member.When pressure on the operating member is released, the valve member is held by its spring against the lower end of the inlet tube until the air valve is completely closed.

In certain circumstances it may be possible for a small quantity of liquid to be dispensed even though air cannot enter the reservoir to replace this liquid because liquid may enter the reservoir from the bottle. Thus, in these circumstances, it would be possible for the quantity of liquid actually dispensed to exceed the required measured quantity.

It is an object of a further aspect of the invention to prevent this possibility by providing a liquid dispensing device of the kind specified, in which, when the operating member is moved from its first position towards its second position, communication between the reservoir and the interior of the bottle is cut off before the passage between the reservoir and the outlet commences to open.

Accordingly from a first aspect the invention consists in a liquid dispensing device of the kind specified, wherein the operating member is longitudinally extending, and the passage to the outlet is constituted by, or includes, an axial bore extending through said operating member from said outlet to a plurality of radial openings placing said bore in communication with the peripheral exterior of the operating member, wherein, when said operating member is in said second position, said openings are located in said reservoir, whereas, until communication between the reservoir and the interior of the bottle has been cut off by movement of the operating member from its first position towards its second position, communication between the reservoir and said openings is cut off by sealing means located between the periphery of the operating member and the reservoir wall.

It is a further object of the present invention to simplify a liquid dispensing device of the kind specified by eliminating the separate valve member and hence also the lost-motion device between the operating member and the valve member.

The invention consists, in this aspect, in a liquid dispensing device of the kind specified in which the upper end of the operating member enters the lower end of the inlet tube before said final stage of its movement to its second position and wherein the relative dimensions of the upper end of the operating member and the lower end of the inlet tube are such that at least a partial seal is formed therebetween before the air valve commences to open.

It will be understood that the arrangement is such that the upper end of the operating member can continue to penetrate into the inlet tube, while the final stage of the movement of the operating member to its second position opens the air valve.

In one embodiment of the invention the upper end of the operating member is arranged so that it provides a complete seal as soon as, or immediately after, it enters the inlet tube. However in most preferred embodiments of the invention the seal at this stage is only partial, and complete sealing occurs at the end of the stroke. In such embodiments the partial seal is provided by the close tolerance between the exterior diameter of the operating member and the internal diameter of the inlet tube. It has been found, quite surprisingly, that provided the operating member is a close slid ing fit in the inlet tube, no liquid passes from the inlet tube into the reservoir even though there is no complete seal formed between the operating member and the inlet tube.

Final sealing of the inlet tube is preferably provided by a tapered or curved shoulder on the operating member. This shaped shoulder butts up against the opening at the lower end of the inlet tube when the air valve has been completely opened. Preferably the shaped shoulder cooperates with a correspondingly shaped seat provided on the lower end of the inlet tube.

In alternative embodiments of the invention the tapered shoulder may be replaced by a flat shoulder supporting an '0' ring or a sealing washer. In yet another arrangement the shoulder is replaced by an annular groove formed in the operating member, and '0' ring or sealing washer being located in this groove.

In the first embodiment referred to above, in which the operating member seals the inlet tube as soon as it enters the tube, the seal may be formed by forming the upper end of the operating member with a deformable annular projection, the diameter of the projection being slightly greater than the internal diameter of the tube. In this arrangement, as the operating member is pushed into the inlet tube, the annular projection is deformed slightly as it slides along the interior of the inlet tube. If desired, the projection could be formed by a separate part attached to the upper end of the operating member.

In a known liquid dispensing device of the kind specified, the passage between the reservoir and the outlet is normally closed by providing on the lower end of the operating member a seal support and a sealing washer which cooperates with a seat formed at the base of the reservoir. In accordance with a subsidiary feature of the invention the necessity for these two additional components is avoided by combining the support with the washer. Preferably the combined support and washer is formed as a lip seal. In other words the lower end of the combined component is flared outwardly and arranged so that, as it is urged by the spring against the seat, it is caused to move slightly outwardly. This outward movement of the seal is effective to clean deposits away from the seat. This cleaning action prevents leakage which may occur with the existing known flat sealing washers.

In a known liquid dispensing device of the kind specified, the air valve normally includes a spring loaded axially slideable valve member formed with a seal support. The actual seal consists of a flat sealing washer which cooperates with a seat in the head of the device. In accordance with a further subsidiary feature of the invention the necessity for this sealing washer is eliminated by forming the slideable valve member with a tapered annular projection which is itself capable of cooperating with the seat in the head of the device to form an airtight seal.

In a liquid dispensing device of the kind specified, the lower part of the operating member consists of a tubular member normally made of metal, which also constitutes the outlet passage. The tubular portion has a number of radial drillings in the vicinity of its upper end which communicate with the hollow interior. Thus liquid from the reservoir flows, when the operating member is in its second position, into these drillings and thence through the outlet passage. The tubular member slides in a corresponding hole in the base of the reservoir.

Thus, in order to avoid leakage when the operating member is moved away from its rest position, a gland seal must be provided below the reservoir and embracing the tubular part of the operating member. In known devices this gland seal is normally provided by a seal support inserted in a hood which conceals the spring and a washer urged by the support against the base of the reservoir. The seal support is dished to allow the washer to deflect in accordance with the direction of motion of the operating member. To avoid the necessity for a two-component seal, a further subsidiary feature of the invention provides that the gland is formed as a single self-supporting member.This member is generally annular in shape, but the wall surrounding the central opening is formed so that the diameter varies smoothly from a clearance fit on the tubular part of the operating member at the lower end of the opening to an interference fit at the upper end. In addition the selfsupporting member is preferably formed with at least two annular ribs on the upper side to form a seal against the base of the reservoir. The self-supporting member may be a separate component, but preferably it is formed as part of the hood moulding.

Finally, in a liquid dispensing device of the kind specified, it is necessary to provide a seal between the head of the device and the upper face of the reservoir. For this purpose it is usual to provide an annular recess on the lower side of the head, and this recess contains a deformable ring which is urged against the upper face of the reservoir to form the seal. In accordance with yet another sub sidiaryfeature of the present invention this seal is formed by providing a plurality of projecting rings on the lower face of the head. These rings are urged against the upper face of the reservoir in the usual way and are deformed slightly to form the required seal.

Embodiments of the invention will now be described with reference to the accompanying diagrammatic drawings in which: Figure 1 is a cross-sectional side view of a dispensing device in accordance with the invention; Figure 2 shows a part of one of the seals used in the device illustrated in Figure 1 in two different positions of the operating member; Figure 3 shows at a, b and c three possible variations of part of the operating ember of the device illustrated in Figure 1; and Figure 4 illustrates a modification of the hood and gland seal used in the device illustrated in Figure 1.

The device illustrated in Figure 1 includes a head 1 which is moulded integrally with an inlet tube 2.

The upper part of the inlet tube 2 is surrounded by a cork 3 which fits in the neck of an inverted bottle, part of which is shown at 4. The inlet tube 2 contains a dividing plate 5, the lower end of which terminates a short distance from the lower end of the inlet tube. The head 1 is secured within a mounting plate 6 by means of screws such as that illustrated at 7.

Secured below the head 1 is a reservoir 8. The lower side of the head 1 is formed with a number of annular serrations 9, and the reservoir is secured to the head 1 by means of an internally threaded ring 10 which cooperates with corresponding external threads of the head 1. When the ring 10 is tightened, the serrations 9 are slightly deformed by the pressure of the flat upper face of the reservoir so that a liquid-tight seal is formed.

The head 1 is moulded with a dependent ring 11 which merely serves to protect the serrations 9 before the head and reservoir are assembled.

The reservoir 8 contains an operating member 12 consisting of synthetic resin material. The lower end of the operating member 12 is hollow, and internally threaded to receive a plunger 13 which is slideable in a corresponding opening 14 in the base of the reservoir 8. Secured to the lower end of the plunger 13 is an arm member 15 having a central boss 16. The boss is externally threaded to cooperate with an internal thread on a ring 17. The plunger 13 is formed with a shoulder 18, and it will be seen that the arm member 15 is loosely retained on the plunger 13 when the ring 17 is tightened up against the shoulder 18.

A helical spring 19 surrounds the plunger 13, and the lower end of the spring bears against a collar 20 which itself bears against a further shoulder 21 formed on the plunger 13. The upper end of the spring 19 bears against a gland seal 22. This seal is formed with annular serrations 23 to form a seal against the lower flat face of the reservoir 8.

The seal 22 is also formed with a central opening surrounding the plunger 13, the diameter of the opening varying smoothly from a clearance fit, with respect to the plunger, on the lower side of the opening to an interference fit at the upper side of the opening. It will be seen that the plunger 13 can be moved upwardly from the position shown in Figure 1 against the action of the spring 19. During this movement the seal 22 serves to prevent any liquid in the reservoir 8 from leaking down the outside surface of the plunger.

The spring 19 is surrounded by a hood 24 secured by adhesive, or other means, to the base of the reservoir 8. The collar 20 slides inside the hood 24 which merely serves to conceal the spring 19 and the gland seal 22.

The operating member 12 is formed at its upper end with a reduced-diameter portion 25. The external diameter of this portion is accurately controlled so that it is a close sliding fit in the lower end 26 of the inlet tube 2. Below the portion 25 is a further portion 27 having a slightly greater external diameter. Between these two portions there is a tapered shoulder 28 which, in accordance with the invention, constitutes the final seal between the operating member 12 and the inlet tube 2. As can be seen in the drawing, the lower end of the inlet tube 2 is preferably formed with a corresponding taper 29.

The lower end of the operating member 12 is formed with a further reduced-diameter portion 30 forming a flat annular shoulder 31. A seal 32 is fitted on the reduced-diameter portion 30. This part of the operating member 12 and the seal 32 is shown in greater detail in Figure 2. The lower part of Figure 2 shows the operating member in the rest position illustrated in Figure 1. In this position the spring 19 urges the operating member downwardly so that the seal 32 is forced against a seat 33 at the base of the reservoir 8.

The upper part of Figure 2 shows the operating member 12 raised above its rest position so that the seal 32 is clear of the seat 33. It will be seen that when the seal 32 is not supported by the seat 33, it assumes a position in which the periphery of the seal is inclined slightly downwardly. When the operating member 12 is moved to its rest position, shown in the lower part of Figure 2, the periphery of the seal 32 is deflected upwardly. At the same time it will be seen that the shape of the seal is such that the periphery is also moved radially outwardly. This movement is indicated in Figure 2 by the two arrows 34 and 35.

The operating member 12 also includes a large diameter portion 36. This portion cooperates with a valve member 37 which is slideable in the head 1.

The valve member 37 is formed with a tapered portion 38 which cooperates with a correspondingly tapered portion 39 formed in the head 1. The valve member 37 is urged downwardly by a helical spring 40, and the components 37-40 constitute an air valve which is normally closed by the action of the spring 40, urging the tapered portion 38 against the seat 39. The spring 40 is retained in the head 1 by a cap 41 which is designed to provide an opening for air to enter the cylindrical space 42 in which the spring 40 is located. It will be seen that, as the operating member is moved upwardly so that the portion 25 enters the inlet tube 2, the portion 36 of the operating member engages the lower end of the valve member 37 and moves it upwardly against the action of the spring 40. This serves to open the air valve and admit air into the reservoir 8.

When it is desired to dispense a measured quantity of liquid from the device illustrated, the operating member 12 is moved upwardly normally by placing a glass below the arm member 15 and pushing the glass upwardly against the action of the spring 19. As the operating member is moved upwardly, the portion 25 is caused to enter the lower end of the inlet tube 2. This prevents liquid from the bottle from passing through the inlet tube to the interior of the reservoir 8. The upward movement of the operating member also moves the seal 32 off the seat 33. However no liquid will be dispensed at this stage, since air cannot enter the reservoir to replace any liquid leaving the reservoir. Continued upward movement of the operating member 12 moves the valve member 37 upwardly and thus allows air to enter the reservoir.

At this stage a plurality of drillings 43 in the plunger 13 are located in the reservoir 8 and, since they communicate with the outlet passage 44 formed in the plunger 13, the contents of the reservoir are allowed to pass through the drillings into the passage 44 and enter the glass from the outlet 45. At this stage the tapered seal 28 will be urged up against the corresponding taper 29 at the base of the inlet tube 2, and accordingly no further liquid will be able to enter the reservoir 8 from the interior of the bottle.

When all the contents of the reservoir have been dispensed into the glass, pressure on the arm member 15 is released and the operating member 12 is returned to the rest position shown in Figure 1 by the action of the spring 19. As a result, further liquid will be able to enter the reservoir from the bottle through the inlet tube 2 so that the device is ready for dispensing a further measured quantity.

Figure 3 shows at a, b and c three possible mod ifications of the upper end of the operating member 12. In the arrangement shown in Figure 3a, an annular groove 46 is formed on the portion 25 and an '0' ring 47 is fitted in this groove. Thus it will be seen that the arrangement in this case is such that a seal is formed between the '0' ring 47 and the interior of the inlet tube 2 as soon as the operating member 12 has penetrated far enough into the inlet tube 2 for the '0' ring 47 to be in contact with the interior of the tube. In this case there is no necessity for the tapered seal 28, although this may be provided in addition if desired.

In this modification shown in Figure 3b, the tapered seal 28 is replaced by an '0' ring 48 resting against a flat shoulder 49 formed on the operating member 12. The operation of the device in this case is similar to that described with reference to Figure 1, namely that the portion 25 of the operating member is dimensioned to provide at least a partial seal when it enters the inlet tube 2, and sealing is completed by cooperation between the '0' ring 48 and the inlet tube.

The embodiment illustrated in Figure 3c is generally similar to that shown in Figure 3a except that the '0' ring 47 is replaced by an annular seal 50 formed on the operating member itself. The material of the seal and the dimensions are arranged so that, as the seal 50 enters the inlet tube 2, the periphery is slightly deflected downwardly to form the seal. If desired, the seal 50 may constitute part of a separate member secured to the operating member, rather than actually being formed on the reduced-diameter portion 25.

In the arrangement shown in Figure 1, the gland seal 22 is a separate member urged against the base of the reservoir 8 by the action of the spring 19. However, if desired, this gland seal may be moulded as part of the hood 24 as shown in Figure 4. This Figure shows particularly clearly the shape of the central portion of the gland seal with its different diameters at the top and bottom of the seal.

In the embodiments of the invention as hereinbefore described, the arrangement is such that the seal 32 is broken as soon as upward movement of the operating member 12, from its rest position, commences. In addition the dimensions are such that the passage between the reservoir and the outlet commences to open before communication between the reservoir and the interior of the bottle is completely cut off. However before communication between the reservoir and the interior of the bottle is completely cut off, and the passage between the reservoir and the outlet is completely open, air cannot enter the reservoir because the air inlet is sealed by cooperation of the tapered portions 38 of the valve member 37 with the corresponding tapered portion 39 formed in the head 1.

Thus the prevention of air entering the reservoir is relied on to prevent any liquid passing from the reservoir to the outlet.

As already mentioned, in the embodiments previously described, the seal 32 moves off the seat 33 immediately upward movement of the operating member commences. Thus it is, at least theoretically, possible for any liquid in the reservoir 8 to pass through the narrow peripheral space between the exterior of the upper end of the plunger 13 and the opening 14 in the base of the reservoir 8. Thus this liquid could reach the drillings 43 which communicate with the outlet passage 44.

Thus one of the first requirements to achieve the object of this further aspect of the invention is to maintain the seal between the upper end of the plunger 13 and the opening 14 in the base of the reservoir 8.

In order to ensure that communication between the reservoir and the interior of the bottle is cut off at a relatively early stage in the movement of the operating member from its first position to its second position, it is preferred that the upper end 25 of the operating member 12 should be of the modified form shown in Figure 3A or Figure 3C. In other words, sealing means such as the '0' ring 47 or the annular seal 50 should be provided on the upper end of the operating member. As already pointed out, with this arrangement a seal is formed to cut off communication between the interior of the bottle and the reservoir soon after the operating member 12 has entered the inlet tube 2.

Another problem which arises with the embodiments of the invention illustrated in Figure 1 is that the ring 10 and the internal shape of the head 1 makes it impossible to see the upper surface of the liquid in the reservoir when the reservoir is full, or almost full. Consequently, if the bottle is aimost empty after a measured quantity has been dispensed it is impossible to see whether or not the reservoir is completely full before the next quantity is dispensed. It is therefore an object of another aspect of the invention to avoid this disadvantage.

From this aspect the invention consists in a liquid dispensing device of the kind specified, wherein the reservoir wall is, or the reservoir walls are, transparent and wherein the upper part, or parts, of the wall, or walls, is, or are, shaped so as to cause upward refraction of generally horizontal light rays incident on the exterior of the reservoir.

Normally the wall, or walls, of the reservoir is, or are, tapered outwardly and upwardly as shown, for example, in Figure 1 of the drawings. In accordance with this aspect of the present invention the inside surface of the wall of the reservoir is inclined at the same angle as shown, for example, in Figure 1, but the angle of inclination of the outer surface of the upper part of the wall is increased so that the thickness of the wall increases smoothly towards the upper edge. This shaping of the upper part of the reservoir wall causes it to act like a prism.A horizontal light ray incident on the exterior surface of the wall will be refracted towards the normal to the surface and, if the divergence between the inner and outer surfaces of the wall is correctly chosen, the beam may be arranged to strike the interface between the inner wall and the air or liquid in the interior substantially at right-angles. As a result, there will be no refraction of the beam leaving the wall, whether the contents of the reservoir are air or liquid. Thus a horizontal light ray will leave the inner surface of the reservoir wall substantially at right-angles to that surface, and accordingly will travel upwardly towards the lower end of the inlet tube. Similarly the line of sight from a point substantially level with the shaped part of the reservoir wall towards the reservoir will be bent upwardly as it passes through the wall.Consequently anyone looking at the reservoir will be able to see the lower end of the inlet tube even though this is located above the point of entry of the line of sight to the reservoir wall. Thus it will be seen that it is always possible to ascertain visually whether or not the reservoir is full of the liquid to be dispensed.

The embodiment of the above described modification of the invention will be described with reference to Figure 5 of the accompanying diagrammatic drawings which is a cross-sectional side view of a modification of the dispensing device illustrated in Figure 1. Parts of the device which are identical, or functionally similar, to the corresponding parts of the device illustrated in Figure 1 are given the same reference numerals and will not be particularly described.

In the embodiment illustrated in Figure 5 the upper end of the operating member 62 is formed generally in the manner shown in Figure 3(a). In other words it is provided with an '0' ring 47 located in a groove formed in the upper end 25 of the operating member. With this arrangement a seal is formed between the '0' ring 47 and the interior of the inlet tube 2 as soon as the operating member 62 has penetrated far enough into the inlet tube 2 for the '0' ring 47 to be in sealing contact with the interior of the tube.

The seal 32 shown on the lower end of the operating member 12 in Figure 1 is replaced in the present modification by an '0' ring 71 which surrounds the plunger 63 which is screwed into the lower end of the operating member 62 in the same way as the plunger 13 is fitted to the operating member 12 of Figure 1, except that a washer 72 is inserted between the plunger 63 and the operating member 62.

The lower end of the reservoir 58 is shaped to form a portion of reduced diameter as shown at 73. The opening through the lower part of the reservoir has a smaller diameter than the lower end of the operating member 62. Thus cooperation between the lower end of the operating member 62 and the portion 73 serves to limit downward movement of the operating member. A spacer 74 surrounds the plunger 63 below the '0' ring 71 and a further '0' ring 75 is located below the spacer.

The hood 24 is provided with an internal flange 76 which is located immediately below the '0' ring 75.

A helical spring 69, which is in compression even when the operating member 62 is in its lowermost position, extends between the collar 20 and the flange 76. Thus this spring urges the flange 76 upwardly and keeps the '0' rings 71 and 75 and the spacer 74 in position below the reduced diameter portion 73.

As in the arrangement illustrated in Figure 1, the plunger 63 is provided with a number of drillings 43 which communicate with the outlet passage 44.

It will be seen that these drillings are located somewhat further below the lower end of the reservoir than in the case of the corresponding drillings in the arrangement of Figure 1. When the plunger 63 is moved upwardly by pressure on the arm member 15, the first operation is the sealing of the inlet tube 2 by entry of the '0' ring 47 into the lower end thereof. At this stage the drillings 43 are still located below the '0' ring 71, and accordingly there is no communication between the interior of the reservoir and the outlet passage 44.

Continued upward movement of the plunger 63 moves the drillings 43 past the '0' ring 71 and into the reservoir 58. As the same time the large diameter portion 36 of the operating member comes into contact with the lower end of the valve member 37, and continued upward movement of the operating member moves the valve member 37 upwardly and thus allows air to enter the reservoir.

As a result the contents of the reservoir are allowed to pass through the drillings 43 into the outlet passage 44.

When the contents of the reservoir have been dispensed, the spring 69 moves the operating member 62 downwardly, and as a result the air inlet is closed and the drillings 43 pass below the '0' ring 71, thus cutting off communication between the interior of the reservoir and the outlet passage 44. Throughout this time the '0' ring 47 remains within the inlet tube 2 and accordingly the contents of the bottle are still sealed from the reservoir. The final stage of the downward movement of the operating member removes the '0' ring 47 from the inlet tube 22 and thus allows the reservoir to refill from the bottle.

In an alternative embodiment, not shown, the reservoir has an outlet opening leading to a downwardly extending passage of a diameter less than the lower end of the operating member, and '0' rings similar to '0' rings 71 and 75 are fixed relative to the plunger above and below the radial drillings so as to be in sliding sealing engagement with the wall of the passage. The operating member and plunger are so dimensioned that the inlet opening of the reservoir is closed by the operating member before the upper of the two '0' rings enters the reservoir to allow communication from the reservoir to the radial grillings.

Two further modifications of the dispenser illustrated in Figure 1 enable the level of the liquid in the reservoir to be seen from outside. The first of these modifications is the omission of the threaded ring 10. This ring would obscure the lower end of the inlet tube 2 and accordingly, in the modification illustrated in Figure 5, the reservoir 58 is secured directly to the head 1 by welding, as diagrammatically illustrated at 77.

The second modification provided for this purpose is the special shaping of the upper portion of the reservoir. As can be seen from Figure 5, the upper part of the reservoir wail is thickened progressively from a point 78 to the upper rim of the reservoir. This portion of the wall acts as a prism to bend the line of sight from the exterior of the reservoir upwardly so that a person viewing the reservoir substantially horizontally is able to see the lower end of the inlet tube. Figure 6 of the drawings illustrates the effect of refraction on a ray of light A emanating from a point B level with a portion of the reservoir wall 58 above the line 78.

The ray A strikes the wall 79 at an oblique angle, and accordingly the ray passing through the material of the wall is refracted towards the dashed line C which represents the normal to the wall 79. This refraction causes the ray to meet the inside surface 80 of the reservoir wall substantially at right-angles and therefore there is no refraction at this surface whether the material in the reservoir is air or a liquid. The inside surface 80 may alternatively be a part-spherical surface centred at the base of the inlet tube 2. It will be seen that the ray A has been deflected upwardly, and accordingly would strike the head 1 of the dispenser at a point in the region of the base of the inlet tube 2. The converse, of course, follows, with the result that the image of the base of the inlet tube 2 can be seen from the outside as if it were located on a level with the point B. If desired, the '0' ring 75 may be replaced by a gland washer. In this case the length of the spacer 74 is increased and the lower end of the spacer, as well as the upper side of the inward end of the flange 76, is chamfered so that the gland washer can be deflected slightly upwardly when the plunger 63 is moved upwardly, and deflected slightly downwardly when the plunger 63 is moved downwardly.

The flange 76, which is integral with the hood 24, may be replaced by a separate washer. In this case the spring 69 will serve to keep the washer in position, but the hood 24 will not be retained by the spring. Accordingly it will normally be secured to the base of the reservoir by means of an interference fit.

Claims (29)

1. A liquid dispenser comprising a reservoir having aligned inlet and outlet openings and an elongate operating member extending through the outlet opening and having at its end adjacent the inlet opening closure means cooperable with the inlet opening, the operating member further having an outlet passage extending from its end remote from the inlet opening and comprising an axial bore communicating with a radial bore, the operating member being axially reciprocable between a first position wherein the closure means is spaced from the inlet opening and communication between the radial bore and the reservoir is prevented by sealing means located between the periphery of the operating member and the reservoir wall, and a second position wherein the radial passage is within the reservoir and the closure means closes the inlet opening, the sealing means remaining interposed between the reservoir wall and the radial passage during movement of the operating member from the first to the second position until the closure means has closed the inlet opening.

2. A liquid dispenser as claimed in claim 1, in which an outlet passage coaxial with the outlet opening leads away therefrom and the operating member is axially movably received in the outlet passage and the sealing means acts between the wall of the outlet passage and the operating member.

3. A liquid dispenser as claimed in claim 2 in which the sealing means is fixed in the outlet passage and the movement of the operating member from its first to its second position causes the radial passage to move past the sealing means.

4. A liquid dispenser as claimed in claim 1 in which the sealing means is fixed in relation to the operating member.

5. A liquid dispenser as claimed in any preceding claims in which a second seal is formed between the operating member and the reservoir, the radial passage of the operating member being situated at all times between the second seal and the reservoir.

6. A liquid dispenser as claimed in claim 5 when dependent on claim 2, in which the second seal acts between the wall of the passage and the operating member.

7. A liquid dispenser as claimed in claim 6, in which the second seal is fixed in relation to the operating member and forms a sliding seal between the outlet passage and the operating member.

8. A liquid dispenser as claimed in claim 5 as dependent on claim 3, and in which the sealing means and the second seal are situated in the outlet passage and are axially spaced from one another.

9. A liquid dispenser as claimed in claim 8 in which a spacer ring is interposed between the sealing means and the second seal.

10. A liquid dispenser comprising a reservoir having aligned inlet and outlet openings, and an elongate operating member extending through the outlet opening and axially reciprocable between first and second positions, a first end of the operating member constituting closure means cooperable with the inlet opening, axially spaced first and second sealing means surrounding the mid-portion of the operating member, and a second end of the operating member having an axial passage communicating with a radial passage intermediate the length of the operating member, the arrangement being such that, in the first portion of the operating member the closure means thereof is spaced from the inlet opening and the radial passage is situated outside the reservoir and between the first and second sealing means; the first sealing means forming a seal between the operating member and the outlet opening of the reservoir, and in the second position of the operating member the closure means thereof closes the inlet opening of the reservoir and the radial passage is situated within the reservoir, and that during movement of the operating member between the first and second positions, the closure means closes the inlet opening before the radial passage enters the reservoir.

11. A liquid dispenser as claimed in claim 10, in which the closure means comprises an end portion of the operating member adapted to enter the inlet opening of the reservoir and effect a sliding sealing engagement therewith.

12. A liquid dispenser as claimed in claim 10, in which the closure means comprises a cylindrical end portion of the operating member of a first diameter terminating in a radially extending shoulder and the inlet opening of the reservoir is circular and has a diameter slightly larger than the first diameter but less than the diameter of the shoulder, the end portion of the operating member preventing passage of liquids through the inlet opening when situated therein, and the shoulder completely blocking the inlet opening when the operating member is in its second position.

13. A liquid dispenser as claimed in claim 12, in which the radially extending shoulder is conical in form, and cooperates with a conical seat formed about the inlet opening of the reservoir.

14. A liquid dispenser as claimed in claims 10 to 13, in which the first and second sealing means are fixed in relation to the reservoir, and are positioned on opposite sides of the radial passage when the operating member is in its first position, and are both situated between the radial passage and the second end of the operating member when the operating member is in its second position.

15. A liquid dispenser as claimed in claim 14, in which the reservoir is arranged as an inverted truncated cone having its inlet and outlet openings situated axially at its upper and lower ends, and having a guide passage extending downwardly from the outlet opening, the first and second seal ing means being situated at the upper and lower ends of the passage, respectively, and being sepa rated by a spacer.

16. A liquid dispenser as claimed in claims 10 to 13, in which the first sealing means is fixed in relation to the operating member, and the second sealing means is fixed in relation to the reservoir, the first sealing means moving into the reservoir when the operating member moves from the first to the second position.

17. A liquid dispenser as claimed in claim 15 in which the operating member extends vertically and has a pair of axially spaced radially extending shoulders, the upper shoulder facing downwardly and abutting the outlet opening of the reservoir to define the first position of the operating member and the lower shoulder facing upwardly and situated adjacent the second end of the operating member, a spring surrounding the operating member and bearing on the lower shoulder to urge the operating member toward its first position, the upper end of the spring urging the second seal means upwardly to retain the first and second seal means and the spacer within the guide passage.

18. A liquid dispenser as claimed in claim 17 in which a washer is interposed between the upper end of the spring and the second seal means.

19. A liquid dispenser as claimed in claim 18 in which the washer is part of a hood surrounding the operating member and the sealing means.

20. A liquid dispenser as claimed in claim 10 in which both the first and second sealing means are '0' rings.

21. A liquid dispenser as claimed in claim 10 in which the first sealing means is an annular sealing ring having a peripheral sealing lip whose seated diameter is greater than its unseated diameter.

22. A liquid dispenser as claimed in claim 21 in which the second sealing means is a lip seal.

23. A liquid dispenser as claimed in claim 22 in which the second sealing means includes a central opening of a diameter greater than the diameter of the operating member, and an inclined sealing lip portion extending radially inwardly from one end of the central opening to the operating member in a sliding sealing engagement.

24. A liquid dispenser as claimed in claim 23 in which the second sealing means forms part of a hood surrounding the operating member.

25. A liquid dispenser according to any preceding claim in which a vent opening is provided in the reservoir adjacent the inlet opening, the vent having a conical seating surface tapering towards the interior of the reservoir, and a vent valve comprising a conical valve seat corresponding to the conical seating surface and an elongate valve operating element, the operating member of the dispenser including an abutment which cooperates with the operating element to open the vent when the operating member is in its second position.

26. A liquid dispenser including a reservoir formed by a transparent side wall and an opaque top wall, and having an inlet opening in the top wall situated above the level of the side wall in which an upper portion of the side wall is increased in thickness so that light rays emanating from the region of the inlet opening exit from the upper portion of the side wall in a generally horizontal direction in use.

27. A liquid dispenser as claimed in claim 26 in which the side wall is cylindrical or conical, and the wall thickness of the side wall is increased towards its upper end so that the inner and outer surfaces of the side wall define cones of different angle.

28. A dispenser as claimed in claim 26 or 27, in which the angle between the inner and outer faces is such that a light ray emanating from the inlet opening strikes the inner face of the side wall nor mally and exits from the outer face horizontally.

29. A dispenser as claimed in claim 26 in which the inner face of the side defines, at its upper extremity, a spherical surface.