WO2009130461A1

WO2009130461A1 - Manual pump type fluid dispenser

Info

Publication number: WO2009130461A1
Application number: PCT/GB2009/001028
Authority: WO
Inventors: Keith Laidler
Original assignee: Leafgreen Limited
Priority date: 2008-04-23
Filing date: 2009-04-22
Publication date: 2009-10-29
Also published as: WO2009130462A9; WO2009130462A1

Abstract

A pump dispenser (20) for mounting to a liquid container comprises a cylindrical type pump arrangement of the type having a mounting member (25) for mounting the dispenser to the container, a generally cylindrical body (23) located within the mounting member for projection into the container, a turret collar (24) for positioning the body within the mounting member, an elongate piston (22) movably mounted within the body, a seal member (26) operative between the piston and an inner surface of the body to define a liquid pump chamber (43) within the body and an actuator (21) mounted to, or operatively connected with, the piston. The dispenser is adapted to provide an air pump chamber (50) at least partially within the actuator and an outlet passageway arrangement of the dispenser includes at least one constricted orifice (36) through which liquid from the liquid pump chamber is passed.

Description

Manual Pump Type Fluid Dispenser

The present invention relates to a manually actuated pump type fluid dispenser and to a method of manufacturing such a dispenser. Many of the manually actuated pump type fluid dispensers used in mass market applications such as food, perfume, body spray, anti-perspirant/deodorant, lotions, pharmaceuticals, soaps, insecticide, paint, and oils etc, use cylindrical pumps having a pump body which is inserted through the neck region of a non-pressurised container for the fluid to be dispensed. In many applications the fluid product which is usually a liquid is dispensed as a fine mist or atomised spray. In most known spray dispensers, the liquid is broken up into small droplets or atomised by forcing the fluid through a very fine outlet orifice or nozzle under pressure. The size of the droplets produced is a function of the size of the orifice, the pressure of the liquid at the orifice and the properties of the liquid. In most applications, the size of the orifice and the properties of the liquid remain substantially constant during the spray cycle so that variations in the pressure of the liquid at the orifice will result in variations in the average droplet size, with a reduction in the pressure leading to an increase in the average droplet size. Ideally, a dispenser should produce a spray in which the average droplet size remains substantially constant throughout the spray cycle. However, in the known pump dispensers, the pressure of the liquid at the outlet orifice varies throughout the spray cycle leading to a corresponding variation in the average droplet size. The beginning and end of the spray cycle are the most problematic with known pump dispensers, as the pressure of the fluid at the spray orifice is at its lowest during these phases. An example of a known cylindrical pump dispenser 1 is shown in Figure 1, which is a vertical cross sectional view through the dispenser. The known cylindrical dispenser has an actuator 2, a piston 3, a body 4, a turret collar 5, a closure 6, a seal valve 7, an inlet ball valve 8, and a spray insert 9. The closure 6, is adapted to be mounted to the outlet neck region of a container (not shown) for the liquid product to be dispensed by means of a screw thread or other twist fit connection (not shown). The body 4 is located in closure 6 by means of the turret collar 5, which also acts as a seal between the closure and the container.

The piston 3 is in the form of a hollow tube closed at its lower end. The piston

3 is slidably mounted in the body 4 of the pump through the turret collar 5 and projects though an opening in the upper end of the body for connection with the actuator 2. The actuator 2 has an outlet passage 10 in fluid connection with the interior of the piston and which leads to a final dispenser outlet formed by the spray insert 9.

The seal valve 7 is mounted about a lower end of the piston adjacent a ledge

11 and engages the wall of the body to define a pump chamber 12 in a lower region of the body, below the seal. Openings 13 through the piston fluidly connect the chamber

12 with the interior of the piston. A first upper spring 14 is located about the piston and biases the seal valve into contact with the piston ledge, where the seal valve closes the openings 13. A second, lower spring 15 contacts the lower surface of the ledge to bias the piston 3, and hence the actuator 2, upwardly and acts as a return spring. The valve seal 7 is configured to be moved upwardly against the bias of the upper spring to open a flow path from the pump chamber through the openings 13 when the pressure of the liquid in the pump chamber 12 is at or above a first threshold amount above ambient. Typically the first threshold amount is in the range of 0.2 to 1 MPa (2 to 10 bars) with 0.3 to 0.6 MPa (3 to 6 bars) being common (all pressures are quoted above ambient).

A lower end of the body is formed into a hollow spigot 16 to which a dip tube (not shown) can be attached to allow liquid to be drawn into the pump chamber from deep within the container. The one-way ball valve 8 is located at the upper end of the spigot 16 to act as an inlet valve to the pump chamber 12. In operation, a user applies a force to depress the actuator 2 and the piston 3.

Initially, because the liquid in the chamber 12 is relatively incompressible, there is little downward movement of the piston 3, seal valve 7 and actuator 2 but the pressure of the liquid in the pump chamber 12 is increased, which forces the ball valve 8 onto its seat closing the inlet to the pump chamber. As the pressure of the liquid in the pump chamber rises, the seal valve 7 is moved upwardly relative to the piston against the bias of the upper spring 14. Once the pressure reaches the first threshold level, the seal valve is moved sufficiently to open a flow path from the pump chamber 12 into the piston and from there to the dispenser outlet. Continued downward pressure on the actuator 2 causes the actuator and piston 2 to be moved downwardly forcing the liquid in the pump chamber through the openings 13, along the piston 3 and the outlet passage to be dispensed.

Dispensing continues until the piston 3 reaches its lowermost position, at which time the pressure of the liquid in the pump chamber 12 falls below the threshold value and the seal valve 7 closes the openings 13. When the user releases the actuator 2, the return spring 15 biases the piston 3 and the actuator 2 upwardly back to the start position as shown in Figure 1, with the upper spring 14 holding the seal valve 7 on the ledge so that the openings 13 remain closed. As the piston is moved upwardly, the volume of the pump chamber is increased which, because the openings 13 are sealed, results in a reduction of the pressure in the pump chamber 12 below ambient opening the inlet valve 8 and drawing a fresh charge of liquid into the pump chamber.

During an initial phase of the dispensing cycle, the piston 3 and outlet passage 10 are substantially empty of liquid product and the air inside is at ambient pressure. A small residue of liquid product may be present in the piston and outlet passage but this will also be at ambient pressure. When the seal valve 7 opens, the pressurised liquid enters the piston and flows towards the dispenser outlet, pushing the air and any residue liquid already present inside the piston towards the outlet passage of the actuator and out through the outlet orifice. As the liquid starts to flow, the pressure of the liquid in the piston and outlet passage increases from ambient until it stabilises at a peak value just above the first threshold value, where it remains for the bulk of the spray cycle. During an end phase of the dispensing cycle once the actuator has been fully depressed, the pressure of the liquid in the pump chamber 12, the piston 3 and the outlet passage 10 falls back to ambient, with the seal valve 7 closing once the pressure falls below the first threshold value. Once the seal valve 7 has closed, the pressure of the liquid in the piston and the outlet passage falls off rapidly but some flow through the outlet orifice may continue. In known cylinder pump dispensers, the entire pump discharge time is usually in the range of 0.2 to 0.8 seconds with 0.3 seconds being common. The initial dispensing phase during which the pressure of the liquid in the piston and outlet passage is increasing may be in the region of 0.07 seconds, whilst the end phase in which the pressure of liquid falls back to ambient may be in the region of 0.05 seconds.

During the initial and end phases of the dispensing cycle, the pressure of the liquid at the spray orifice is lower than the peak operating pressure during the main phase of the dispensing spray cycle leading to a significant increase in the droplet size at these times, which in turn increases the average droplet size over the whole dispensing cycle. The angle and form of the spray are also adversely affected by the lower pressure and some products may jet at these times rather than forming a spray. During the end phase, the liquid product may dribble through the outlet orifice if there is insufficient energy in the system to eject all the liquid. This is a particular problem as it is unattractive to end users and can result in blocking of the spray orifice as the remaining liquid may dry out leaving a residue which builds up over time to block the outlet orifice. This problem is exacerbated if particulates are present in the liquid or the orifice is very small. In addition, many products can go off once exposed to the air so that any liquid remaining in the outlet passage and orifice may contaminate the fresh product when the dispenser is next actuated. This is potentially a serious problem where pharmaceutical and food products are concerned.

Other known types of manual pump dispenser exhibit similar variations in the pressure of the liquid at the spray orifice over the dispensing cycle.

One solution to the above problems is to use an air dispenser including an air pump chamber to introduce pressurised air into the liquid so that the two flow through the system together. Mixing air with the liquid is known to improve atomisation of the liquid and the flow of air can be used to maintain the rate of flow of liquid through the outlet orifice even when the pressure of the liquid is below optimum at the beginning and end phases of the dispensing cycle. Occasionally, air pump dispensers will be designed so that the air starts to flow through the system before the liquid exits the liquid pump chamber and continues to flow after the outlet valve of the liquid pump chamber has closed. This is beneficial as the early flow of air helps to draw the liquid through the system and out of spray orifice, whilst the continuing flow of air at the end of the cycle pushes any remaining liquid out, reducing spluttering and dribbling.

Known air pump dispensers have a second pump chamber in which air is compressed when the actuator is depressed, the outlet of the second chamber being connected with liquid flow path to the outlet. The ratio of air to liquid delivered by the known air pumps is typically in the range of 10: 1 to 20:1. The known air pumps are arranged so that the pressure of the air exiting the air chamber and the pressure of the liquid exiting the liquid pump chamber are matched as the product is dispensed. This is necessary so that the air and the liquid can be merged. The need to deliver relatively large volumes of air and to match the pressure of the air and the liquid means that air pumps tend to be larger, more complex and so more expensive to manufacture than equivalent conventional cylinder pumps with no air chamber. They also require much greater actuation forces. The additional manufacturing costs, size and actuation forces associated with air pumps means that they have not made significant inroads in mass market applications, despite producing far superior sprays. A further barrier to market for air pumps is the high cost of tooling and assembly equipment required to introduce any new dispenser pump, which restricts to amount of new devices coming onto the market, irrespective of the nature of the device.

Manual pump dispensers are also known which dispense a fluid product, usually a liquid or gel product, in the form of a foam. Current foam dispensers also have an air chamber and tend to mix air and the fluid product at low pressures, in the region of 0.05 MPa to 0.3 MPa (0.5 to 3 bars) but with high ratios of air to liquid. A ratio of air to liquid in the range of 10:1 to 20: 1 is typical. Due to the high volume of air required to produce these ratios, the dispensers tend to be large. Often the whole, or a significant part, of the dispenser is located within the neck of a bottle containing the fluid product. Accordingly, the bottle neck must be sufficiently large to contain the dispenser. Furthermore, tin the known arrangements, the combination of bottle and dispenser is often top heavy and prone to toppling over. There is a need therefore for an improved manual pump dispenser that overcomes or at least mitigates the problems of the known manual fluid and air pump dispensers.

There is also a need for an improved manual pump dispenser that can be brought to market without incurring prohibitive tooling and assembly equipment costs.

There is a further need for an improved method of manufacturing a manual pump dispenser that enables a new pump to be brought to market without incurring prohibitive tooling and assembly equipment costs. In accordance with a first aspect of the invention, there is provided a pump dispenser for mounting to a container for holding a liquid to be dispensed, said dispenser comprising a liquid pump for pumping liquid from said container, an air pump for pumping air to be dispensed with the liquid and a common actuator to simultaneously actuate the liquid pump and the air pump, the dispenser having an outlet and a fluid passageway arrangement for fluidly connecting the liquid pump and the air pump with the outlet, in which the dispenser comprises a mounting member for mounting the dispenser to the container, a generally cylindrical body located within the mounting member for projection into the container and a turret collar for positioning the body within the mounting member, the dispenser further having a piston movably mounted within the body, a seal member operative between the piston and an inner surface of the body to define a liquid pump chamber within the body, the actuator being mounted to, or operatively connected with, the piston, the dispenser having means for defining an air pump chamber within the actuator, in which the dispenser outlet passageway arrangement comprises at least one constricted orifice through which liquid from the liquid pump chamber is passed.

The dispenser may be configured so that when mounted to a container, all, or a significant majority, of the air pump chamber is located externally of the container.

The dispenser may be configured so that when mounted to a container, the whole of the air pump chamber is located within the actuator about an exposed portion of the piston externally of the container. The dispenser may comprise an outlet valve arrangement for controlling release of the liquid from the liquid pump chamber and air from the air pump chamber during a dispensing phase when the dispenser is actuated, the outlet valve arrangement being configured such that the ratio of air to liquid dispensed varies over the course of the dispensing phase during each actuation. The outlet valve arrangement may be configured such that the ratio of air to liquid dispensed is higher during at least one of an initial and an end phase of the dispensing cycle than during a main phase of the dispensing cycle. The outlet valve arrangement may be configured so that no air is dispensed during the main phase of each dispensing cycle. The outlet valve arrangement may be configured so that air is only dispensed during the end phase of each dispensing cycle.

The dispenser may be configured such that in use, the air in the air pump chamber is raised to a peak pressure which is less than the peak pressure achieved by the liquid in the liquid pump chamber over the dispensing cycle. The dispenser may be configured such that the liquid in the liquid pump chamber is raised to a peak pressure in the range of 0.3 MPa to IMPa (3 to 10 bar), and more particularly in the range of 0.4 MPa to 0.6Mpa (4 to 6 bar), the air in the air pump chamber being raised to a peak pressure in the range of 0.05 MPa to 0.3 MPa (0.5 to 3 bar).

The dispenser may be configured such that air is dispensed from the air pump chamber at a higher pressure during an end phase of the dispensing cycle than during other phases of the dispensing cycle.

The dispenser may be configured such that the total ratio of air to fluid dispensed over each dispensing cycle is in the range of 4:1 to 12:1.

The actuator may be closed at one end and may have an annular wall extending towards the mounting member and the dispenser may comprise an air chamber seal arrangement operative to define a variable volume air pump chamber at least partly contained within the internal volume of the actuator.

An interior region of the body surrounding the piston above the seal member may be in fluid connection with the interior of the actuator to form an extension of the air pump chamber. Alternatively, the dispenser may have a seal operative to fluidly isolate an interior region of the body surrounding the piston from the air pump chamber.

In one embodiment, the seal arrangement comprises an air chamber seal operative between the turret collar and an inner surface of the annular wall to define the air pump chamber. In this embodiment, the dispenser may also comprises a seal operative to fluidly isolate an interior region of the body surrounding the piston from the air pump chamber, such that the whole of the air pump chamber is defined within the interior of the actuator. The air chamber seal may be an integral part of the turret collar or it may be a separate seal member mounted to the turret collar. In an alternative embodiment, the seal arrangement comprises an air chamber seal operative between the annular wall and a surface of the mounting member to define the air chamber. The mounting member may comprise an annular flange that projects towards the actuator, the annular wall of the actuator and the flange overlapping in close relation when the actuator is depressed, and the air chamber seal arrangement may include a seal operative between the flange and the actuator wall to define the air pump chamber. The air chamber seal arrangement may comprise a resilient seal member integrally formed on an end region of the actuator wall for engagement with the flange.

In a further alternative embodiment, the seal arrangement may comprise a flexible member connected between the annular wall and one of the turret collar and the mounting member to define the air pump chamber. The flexible member may be one of a bellows and a rolling diaphragm.

The outlet valve arrangement may comprise a pre-compression liquid pump chamber outlet valve configured to open to allow liquid to exit the liquid pump chamber only when the pressure of the liquid in the liquid pump chamber is higher than atmospheric by a first predetermined amount.

The outlet valve arrangement comprises a one-way outlet valve for the air- pump chamber. The air pump chamber outlet valve may be a pre-compression valve configured to open to allow air to exit the air pump chamber only when the pressure of the air in the air pump chamber acting on one side of the valve is higher than the pressure of the fluid acting on the other side of the valve by a second predetermined amount.

The dispenser may be configured so that the air is mixed with the liquid in a low pressure region of the outlet fluid passageway. Where the dispenser is a spray dispenser in which the constricted orifice is a spray nozzle forming part of a final outlet of the dispenser, the outlet passageway arrangement may be configured to introduce air from the air chamber into the liquid flow path in a swirl chamber immediately upstream of the spray nozzle or the outlet passageway arrangement may include at least one expansion chamber upstream of the spray nozzle and the outlet passageway arrangement may be configured to introduce air from the air chamber into the liquid flow path within the expansion chamber.

The dispenser may be a foam dispenser in which the outlet includes a foam passage and the constricted orifice may be configured to produce a spray, jet or sheet, more particularly a spray or sheet, of liquid upstream of the foam passage. The constricted orifice and at least part of the least part of the foam passage into which the orifice opens may be located within the actuator.

Where the dispenser is a foam dispenser, the outlet passageway arrangement may be configured to introduce air from the air chamber into the liquid flow path downstream from the constricted orifice. In one arrangement, the outlet comprises a mixing chamber and the constricted orifice is configured to direct liquid into the mixing chamber in use, the outlet passageway arrangement being configured to direct air from the air chamber into the mixing chamber.

Where the dispenser is a foam dispenser having a foam passage, the foam passage may include a filter arrangement for refining the foam which comprises of at least two regions of open celled foam spaced apart in the direction of flow. The at least two regions may be formed as an integral plug of open celled material received within the foam passage, the plug having at least one slot or cavity extending part way across the plug to form a gap between the spaced regions.

The dispenser may comprise an arrangement which permits the actuator to move relative to the mounting member to compress the air pump chamber before an outlet valve of the liquid pump chamber opens in use. The arrangement may comprise a compressible member located in the liquid pump chamber or the dispenser may be configured to draw a volume of air or other gas into the liquid pump chamber. Alternatively, the actuator may be operatively connected with the piston by means of a linkage configured to enable the actuator to move towards the mounting member by a predetermined distance before pressure is applied to the liquid by the piston and seal member. In a further alternative arrangement, an opening is provided in the body part way along the liquid chamber, the arrangement being such that when the actuator is depressed, the piston and seal member are able to move relative to the body until the seal member closes the opening before liquid in the chamber is pressurised.

The piston may have an internal bore forming part of an outlet flow path from the liquid chamber to the dispenser outlet, and the air chamber outlet may comprise at least one opening in a wall of the piston fluidly connecting the air chamber with the bore and a resiliently deformable valve member mounted in the bore, the valve member contacting an inner surface of the piston to close the opening in an initial resiliently biased configuration and being configured to deform away from the surface to allow air to enter the bore through the opening when the pressure of the air in the air chamber is greater than the pressure inside the bore by a second predetermined amount. The valve member may be a valve sleeve. The piston may have an internal bore forming part of an outlet flow path from the liquid chamber to the dispenser outlet and the air chamber outlet may comprise at least one opening in a wall of the piston for fluidly connecting the air chamber with the bore and a valve member slidably engaging an outer surface of the piston, the valve member having one or more openings which are configured to align with the opining in the piston to allow air to enter the bore when the piston is moved relative to the valve member by a predetermined amount during actuation of the dispenser. The opening in the valve member may be configured to align with the opening in the piston only during an end phase of each dispensing cycle. There may be two openings in the valve member, a first of the openings being configured to align with the opening in the piston only during an initial phase of each dispensing cycle and a second of the openings in the valve member being configured to align with the opening in the piston only during an end phase of each dispensing cycle

The piston may have an internal bore forming part of an outlet flow path from the liquid chamber to the dispenser outlet, the actuator having an inner portion defining a further bore in which a free end of the piston is received, the further bore also forming part of the outlet flow path for the liquid, in which case, the air chamber outlet may comprise a fluid path from the air chamber into the further bore and a valve member for controlling the flow of air into the further bore from the flow path, the valve member being resiliently deformable from an initial biased configuration in which it closes the flow path to a deformed configuration in which the flow path is opened when the pressure of the air in the flow path acting on one side of the valve member is greater than the pressure acting on the other side of valve member by said second predetermined amount. In one embodiment, the flow path comprises a groove between the piston and the inner portion and an opening in the piston at or close to the free end through which air can flow from the groove to enter the further bore when the valve member is open, the valve member comprising a valve sleeve located in the piston bore close to the free end, at a least a portion of the sleeve being resiliently deformable between a resiliently biased position in which it abuts an inner surface of the piston to close the opening and a deformed position in which it is displaced away from the surface to allow air to pass through the opening. In an alternative embodiment, the valve member comprises a resiliently deformable annular valve member mounted between the free end of the piston and the surface of the inner portion within the further bore, the valve member being deformable from an initial resiliently biased configuration in which it prevents air flowing between the free end of the piston and a surface of the inner portion to enter the further bore and a deformed condition in which air is able to flow past it to enter the further bore. The valve member may be an O-ring.

Where the dispenser is a foam dispenser, the constricted orifice may be a fan jet nozzle adapted to produce a sheet of liquid or a conical jet nozzle adapted to produce a conical sheet of liquid. A pre-compression outlet valve for controlling the flow of liquid from the liquid chamber to the outlet may be located adjacent the constricted orifice, the pre- compression outlet valve being configured to open to allow liquid to flow to the orifice only when liquid at the valve is at or above the first threshold pressure. The dispenser may be configured such that in use during each dispensing cycle, air begins to flow through the outlet passageway arrangement before liquid is released from the liquid pump chamber. In addition or alternatively, the dispenser may configured such that in use during the dispensing cycle, air continues to flow through the outlet passageway arrangement for a limited amount of time after all the liquid has been dispelled from the outlet passageway.

In accordance with a second aspect of the invention, there is provided a method of manufacturing a pump dispenser in accordance with the first aspect, the method comprising: modifying the design of a pre-existing cylindrical liquid only pump dispenser to incorporate the air pump arrangement; manufacturing the pump dispenser using at least some of the original tooling used to produce the pre-existing cylindrical liquid pump dispenser.

The method may comprise modifying some of the original tooling and using the modified tooling to produce modified components for the pump dispenser. Several embodiments of the invention will now be described with reference to the remaining drawings, in which:

Figure 2 is a longitudinal cross sectional view through a first embodiment of a manual pump dispenser in accordance with the invention;

Figure 3 is a longitudinal cross sectional view through a second embodiment of a manual pump dispenser in accordance with the invention;

Figure 4 is a cross sectional view through an actuator cap assembly forming part of the dispenser of Figure 3;

Figure 5 is a longitudinal cross sectional view through a third embodiment of a manual pump dispenser in accordance with a the invention; Figure 6 is a longitudinal cross sectional view through a fourth embodiment of a manual pump dispenser in accordance with the invention;

Figure 7 is a longitudinal cross sectional view through a fifth embodiment of a manual pump dispenser in accordance with the invention; Figures 8 and 9 are longitudinal cross sectional views through a sixth embodiment of a manual pump dispenser in accordance with the invention, showing the dispenser in an initial start condition prior to actuation and in mid-actuation with the actuator fully depressed respectively;

Figure 10 is a longitudinal cross sectional view through a seventh embodiment of a manual pump dispenser in accordance with the invention;

Figure 11 is a cross sectional view through an alternative actuator for use with a dispenser as shown in Figures 7 to 10;

Figures 12a and 12b are longitudinal cross-sectional views taken at 90° to one another through part of a dispenser in accordance with the invention illustrating an alternative outlet valve arrangement for the air pump chamber;

Figures 13a and 13b are longitudinal and lateral cross sectional views respectively through a modified filter plug suitable for use in a dispenser in accordance with the invention;

Figures 14a and 14b are longitudinal and lateral cross sectional views respectively through a further modified filter plug suitable for use in a dispenser in accordance with the invention;

Figure 15a is a longitudinal cross sectional view through an outlet arrangement for a dispenser in accordance with the invention adapted to produce foam;

Figure 15b is a lateral cross sectional view through an end wall of the outlet arrangement of Figure 15a taken on line X-X;

Figure 16 is a longitudinal cross sectional view through a further embodiment of an outlet arrangement for a dispenser in accordance with the invention adapted to produce foam; Figure 17 is a longitudinal cross sectional view through a yet further embodiment of an outlet arrangement for a dispenser in accordance with the invention adapted to produce foam;

Figure 18a is a longitudinal cross sectional view through a flood jet arrangement for use in an outlet passage of a dispenser in accordance with the invention;

Figure 18b is an end view of the flood jet arrangement of Figure 18a, taken in the direction of arrow Y; and

Figures 19a and 19b are cross sectional views through part of the outlet region of a dispenser in accordance the invention showing an alternative pre-compression outlet valve arrangement in an open and a closed condition respectively.

Figure 2 shows a first embodiment of a manual pump dispenser 20 in accordance with the invention. The dispenser 20 is a modified cylindrical pump dispenser of the type described above in the introductory portion. Accordingly, the dispenser 20 comprises an actuator 21, a piston 22, a body 23, a turret collar 24, a closure 25, a seal valve 26, an inlet ball valve 27, and a spray insert 28.

The actuator 21 is generally cylindrical in shape with a closed upper end 29, an outer tubular wall portion 30, and an inner tubular wall portion 31. The inner tubular wall 31 is shorter than the outer wall 30 and is dimensioned to receive an upper end of the piston 22 in a conventional manner.

An outlet for the dispenser is formed in the actuator 21 by means of a generally horizontal (as shown) tube extending between the inner and outer tubular walls 31, 30. The tube defines a cylindrical passage 32 that is in fluid communication with a bore 33 in the piston and a further bore defined within the inner tubular wall 31 by means of an orifice 34 through the inner tubular wall 31 and which opens though the outer tubular wall 30. The spray insert 28 is a close fit in the cylindrical passage 32 and defines an inner chamber 35 in fluid communication with the orifice 34. A constricted orifice 36 is formed in an end wall of the insert through which fluid can exit the chamber 35. In the present embodiment, the constricted orifice 36 is a spray nozzle which breaks up the liquid passing through it into droplets to form a fine mist or atomised spray. The spray orifice 36 opens into a conical recess in the outer face of the end wall of the insert and forms a final outlet orifice of the dispenser. The chamber 35 may be shaped so as to promote swirling of the liquid about the axis of the final outlet orifice 36. Alternatively, a swirl chamber may be provided by means of a projection on the actuator, which engages in the spray insert. This swirl arrangement is described in detail below in relation to the embodiment shown in Figures 3 and 4. The shape of the final outlet orifice 36 can be varied as desired to promote atomisation and to produce a desired spray pattern as is known in the art and there may be more than one final outlet orifice. The term "constricted orifice" in this context refers to an orifice having a cross sectional area which is smaller than the cross sectional area of the liquid flow passage immediately upstream of the orifice. Where the dispenser is a spray dispenser, the orifice will be a spray nozzle that is configured so that liquid forced through it under pressure is broken up into droplets to form a fine mist or atomised spray as noted above. In embodiments in which the dispenser is adapted to dispense a foam or mousse, as will be described later, the constricted orifice 36 may be a spray orifice or it may be configured to produce a jet or a sheet of liquid.

The closure 25 has a main body portion 38, which is adapted to be mounted to the outlet of a container (typically a bottle) for the liquid to be dispensed by means of a screw thread or other arrangement (not shown) in a known manner. Usually, the closure 25 is mounted to a neck region of the container but this is not necessarily the case. A pair of spaced annular flanges 39, 40 project upwardly (as shown) from the main body portion 38 towards the actuator 21, with an annular recess 41 being defined between the inner and outer flanges. The outer flange 39 is longer than the inner flange 40 and is dimensioned so that the outer tubular wall 30 of the actuator is a fairly close sliding fit inside the outer flange 39. When the actuator is depressed, the outer wall 30 of the actuator is received in the recess 41 between the two flanges 39, 40. This arrangement prevents the actuator from wobbling during actuation of the dispenser. The inner flange 40 defines an opening through which the piston 22^uand body

23 project into the fluid container (not shown). The turret collar 24 is mounted to an upper end of the body 23 and serves to locate the body within the opening defined by the inner flange 40 and to slidably support the piston 22 within the body 23 in a known manner. The turret collar has an inner flange portion 42, which is clamped between the closure 25 and the container to form a seal in use. The piston 22 is generally cylindrical in shape and has a central bore 33 which is open at the upper end, into the interior of the inner tubular wall 31 of the actuator 21, and closed at the lower or inner end. The seal valve 26 locates about a lower end region of the piston and forms a seal between the piston 22 and the inner surface of a reduced diameter portion 23a of the body to define a liquid pump chamber 43 within the body below the seal. One or more openings 44 in a side wall region of the piston fluidly connect the interior bore 33 with the liquid pump chamber 43 to define an outlet for the pump chamber. The openings 44 are formed in a reduced diameter end region 22a of the piston and open into a groove 45 in the outer surface of the body. The seal valve includes an inner flap 46 which resiliently engages with the surface of the piston over the groove to form an outlet control valve for the pump chamber 43. When the actuator is depressed the pressure of the liquid in the chamber 43 rises and causes the piston 22 to move downwardly relative to the seal valve until the flap 46 is moved off the groove to open a flow path from the pump chamber 43 through the opening(s) 44. The valve is configured so that the flow path opens when the pressure of the liquid in the pump chamber reaches a first threshold value above ambient, as will be described in more detail later.

Although not shown in Figure 2, a combined return and valve control spring is located in the body 22 in engagement with the seal valve 26 in a similar manner to the spring 85 in the embodiment shown in Figures 8 and 9. A detailed description of the construction and operation of the spring 85 is set out below in relation to the sixth embodiment to which the reader should refer.

A spigot 48 on the lower end of the body is dimensioned to receive a dip tube

(not shown) through which liquid can be drawn into the liquid pump chamber 43 from deep within the container in the usual way. A ball valve 27 in the body acts as a one- way valve to admit liquid into the pump chamber 43 through the dip tube when the pressure in the chamber falls below ambient but is pressed into engagement with a valve seat 49 when the dispenser is actuated to close off the inlet to the pump chamber.

As so far described, the cylindrical pump dispenser 20 is largely conventional and functions to pump liquid from a container to the outlet in the same way as the prior art dispenser 1 described above. However, in accordance with one aspect of the invention, the dispenser 20 has been modified to provide an air pump chamber 50 from which air can be mixed with the liquid during the dispensing cycle.

The turret collar 24 is modified to include a frusto-conical seal member or flange 51 that engages the inner surface of the outer tubular wall 30 of the actuator so as to define the air pump chamber 50 within the interior of the actuator 21. The air pump chamber 50 surrounds a region of the piston 22 which is exposed within the actuator. An opening 52 is formed in the wall of the piston within the actuator to fluidly connect the air pump chamber 50 with the inner bore 33 of the piston and a tubular valve member 53 is located within the bore 33 adjacent the opening to act as a one-way valve for admitting air into the bore 33 during the end phase of the spray cycle whilst preventing liquid in the bore from exiting through the opening 52.

The tubular valve member 53 locates in an enlarged diameter region 54 of the bore 33 and sits on a shoulder 55 formed at the junction between a larger diameter portion 54 of the bore and a main smaller diameter portion 56. At least the part of the tubular valve that is positioned adjacent the opening 52 is resiliently deformable so that in an initial resiliently biased configuration it engages the inner surface of the piston to close the opening 52. The tubular valve member is configured so that it can be deformed inwardly to allow air to pass through the opening 52 to enter the bore 33 when the pressure of the air in the air chamber 50 is greater than the pressure inside the valve member by a second threshold amount. The second threshold pressure being less than the first threshold pressure at which the outlet valve 26 of the liquid pump chamber opens. The tubular valve member 53 therefore acts as a pre-compression valve to ensure that air is only expelled from the air chamber once it reaches a desired pressure above the pressure inside the valve member. A groove can be provided in the inner surface of the piston leading upwardly from the opening 52 along which the air can flow when the tubular valve member is deformed. Operation of the dispenser 20 will now be described, for the purposes of which it is assumed that the pump chamber 43 is primed with a liquid product and the air chamber 50 is full of air. In this embodiment, the seal valve 26 is configured to open when the pressure of the liquid in the liquid pump chambers reaches 0.3 MPa (3 bar) above ambient and the tubular valve is set to open at a threshold pressure of 0.05 MPa (0.5 bar) above the internal pressure inside the tubular valve. The pump discharge time is 0.4 seconds. It will be appreciated, however, that the invention is not limited to the specific values used in this embodiment, which are exemplary only.

When a user applies a force to depress the actuator 21, the pressure of the liquid in the liquid chamber 43 is increased. Depending on the amount of free play in the system, the pressure of the air in the air chamber 50 may also be raised slightly.

After approximately 0.005 seconds, the liquid in the liquid chamber 43 reaches the 0.3 MPa (3 bar) first threshold amount above ambient and the seal valve 26 opens so that liquid starts to flow through the piston bore 33 and the tubular valve member 53. As this liquid begins to flow, the piston 22 and seal valve 26 are able to move downwardly in the body and the actuator 21 moves closer to the closure 25. This reduces the volume of the air chamber 50 and so raising the pressure of the air which impinges on the tubular valve member 53 through the opening 52. However, the pressure of the liquid in the bore 33 and the tubular member 53 rapidly rises pushing the valve into contact with the wall of the piston closing off the air hole 52. In the present embodiment, this takes place at approximately 0.07 seconds into the spray cycle.

The liquid continues to flow through the piston bore 33 and through the outlet orifice 36 in the manner of a conventional cylindrical pump until the liquid chamber 43 is empty or nearly empty at which point the pressure of the liquid flowing through the bore 33 and the tubular valve member 53 rapidly drops, with the valve seal 26 closing once the pressure of the liquid in the liquid chamber 43 falls below the first threshold amount. Meanwhile, the pressure of the air in the air chamber 50 has continued to increase as the actuator 21 is depressed, reducing the volume of the air chamber 50. At approximately 0.3 seconds into the spray cycle, the pressure of the liquid in the tubular valve member falls below the pressure of the air in the air chamber 50 by the second threshold amount. The tubular valve member 53 is deformed inwardly, admitting pressurised air from the air chamber 50 through the air hole 52 into the bore 33 where it mixes with the liquid and the mixture flows to the outlet orifice 36. The dispenser 20 is configured so that pressurised air from the air chamber 50 continues to flow into the bore 33 and through the outlet orifice after all of the liquid has been cleared from the bore 33 to drive out any remaining liquid in the system between the bore 33 and the outlet orifice 36. Once the pressure in the air chamber 50 falls to less than the second threshold amount above the pressure inside the valve (which at this stage is at or close to ambient), the tubular valve closes. Once the dispensing cycle is complete, the actuator 21 is released and the return spring biases the piston 22 and the seal valve 26 upwardly drawing in a fresh charge of liquid into the liquid chamber 43. At the same time, the actuator 21 is moved upwardly away from the closure member increasing the volume of the air chamber 50. As the air hole 52 in the piston is sealed by the tubular valve member 53, the pressure inside the air chamber 50 falls below ambient and the ambient air acting on the outer surface of the flange 51 deforms it inwardly so that a fresh charge of air is drawn into the air chamber.

Mixing air with the liquid during the end phase of the spray cycle improves atomisation of the liquid during a period when the pressure of liquid flowing through the outlet orifice 36 is below the normal operating pressure. This reduces the droplet size during the end phase and so reduces the average droplet size over the whole spray cycle. In addition, the continued flow of air after the liquid has been cleared from within the piston bore helps to drive out any remaining liquid in the outlet region of the dispenser, improving atomisation and reducing the tendency for the dispenser to splutter and dribble. Furthermore, because the continuing airflow drives all the liquid from within the piston bore 33 and the outlet region through the outlet orifice 36, no liquid remains to go off and contaminate fluid product dispensed in later actuations or to dry out and block the outlet orifice. The quality of the spray produced by a dispenser 20 in accordance with the invention is therefore improved over a comparable conventional cylinder liquid pump and the chances of the outlet orifice becoming blocked or contaminated are much reduced. Because the dispenser 20 in accordance with the invention only delivers air during the end phase of the dispensing cycle, a much smaller volume of air is required than an equivalent conventional air pump in which air is introduced over the whole of the dispensing cycle at a substantially constant rate. In a dispenser 20 in accordance with the invention, the air to liquid ratio over the whole of the dispensing cycle may be in range of 4:1 to 12:1 but is more preferably in the range of 6:1 to 8: 1. This compares with a conventional air pump in which the ratio will typically be in the range of 10:1 to 20:1. As a result, the air chamber 50 can be smaller than that required in an equivalent conventional air pump so that a dispenser 20 in accordance with the invention can be provided that is not significantly larger than a conventional cylindrical liquid only pump dispenser. Indeed, in many cases, an existing cylindrical liquid pump dispenser design can be modified to incorporate the air chamber within the existing actuator so that there is no increase in the overall size of the dispenser 20.

One of the biggest problems with the conventional air pumps is the increased actuation force required to compress the air to the same pressure as the liquid during the main discharge phase of the dispensing cycle. In a dispenser in accordance with the invention, the increase in actuation force compared with an equivalent conventional liquid only cylindrical pump dispenser is much less. This is partly due to the fact that a smaller volume of air is being compressed but also because the air does not have to be compressed to match the peak operating pressure of the liquid during the main discharge phase. In this regard it should be noted that in the present embodiment the pressure of the air in the air chamber 50 is only increased to something in the range of about 0.2 to 0.25 MPa (2 to 2.5 bar) during the main discharge phase before the pressure of the liquid in the piston bore 33 starts to fall during the end phase. In addition, the flange 51 is configured to give way easily when the actuator is returned to the start position by the return spring, so that the return spring need only be slightly stronger than that used in a conventional cylindrical pump. This also helps to keep the increase in actuation force to a minimum.

The dispenser 20 according to the present embodiment is designed to introduce airflow into the liquid flow principally during the end phase of the spray cycle only. If the air pressure in the chamber 50 is raised above the threshold value at which the tubular valve member 53 opens during the initial phase before the pressure of the liquid inside the valve increases to a level at which the valve is closed (i.e. pressure of liquid = the pressure of the air less the threshold value at which the valve opens), then some air may also be admitted into the piston bore 33 during the initial phase. This can be beneficial as the flow of air helps to draw the liquid through the system more quickly and so improves the atomization of the liquid when the pressure of the liquid is below the optimal operating pressure. Generally speaking, a tubular valve having a lower stiffness is required where air is to be mixed with the liquid during the initial phase. In some applications it may be desirable to introduce a more significant flow of air into the piston during the initial phase. To achieve this, the dispenser 20 is modified so that the actuator 21 is able to move relative to the closure 25 in order to reduce the volume of the air chamber 50 and raise the pressure of the air in the chamber above the second threshold value, 0.05 MPa (0.5 bar) in this case, before or at the same time as the seal valve 26 opens to allow the liquid to flow from the liquid pump chamber 43. There are numerous ways in which this can be achieved. One approach is to modify the piston to incorporate a flexible region, which can be compressed when the actuator is depressed, or to split the piston into two or more parts that can be moved relative to one another to provide the required actuator movement. The flexible region could be in the form of a bellows, for example. Alternatively, an additional component may be provided between the piston and the actuator to allow for the required movement. In a further alternative arrangement, the actuator with the outlet passage and nozzle can be separated from the piston to allow for the required movement. In this embodiment, a valve may be provided in the actuator to normally close the outlet passage and nozzle, the valve being opened when the piston is brought into contact with the actuator to establish a flow path for the liquid once the actuator has been moved through the required distance. With any of these arrangements, when the actuator 21 is depressed, it is able to move towards the closure 25 to pressurise the air to a required level before a force is applied to the seal valve 26 to pressurise the liquid in the liquid chamber 43. Once the movement in the piston 22 is taken up, further depression of the actuator 21 will result in a force being applied to the seal valve to pressurise the liquid, with the seal valve 26 and the air valve 53 opening once the liquid and the air reach their appropriate threshold pressures. Usually, the dispenser will be configured so that tubular air valve 53 opens to admit air into the piston at the same time or slightly before the seal valve 26 opens. A different approach to enabling relative movement between the actuator and the mounting member to pressurise the air in the air chamber 50 before the liquid valve 26 opens is to introduce a compressible substance or material into the liquid chamber pump chamber 43. A simple way of achieving this is to allow air to be drawn into the liquid pump chamber 43 along with the liquid, so that when the dispenser is actuated, the air in both chambers compresses before the pressure in the liquid chamber is raised sufficiently to open the seal valve 26. A volume of air can be drawn into the liquid chamber 43 through the final outlet orifice and the seal valve 26, for example. Alternatively, a hollow ball or other compressible object could be placed in the liquid chamber 43, so that initial movement of the actuator 21 and piston 22 squashes the ball or object allowing sufficient movement of the actuator to raise the pressure of the air in the air chamber 50 before the liquid seal valve 26 opens. Where a ball is used, the ball could also function as the inlet valve ball 27.

A further alternative arrangement for enabling movement of the actuator before the seal valve 26 opens is to form an opening or hole in the body 22 within the liquid chamber 43. The hole is positioned part way between the lower end of the seal valve 26 and the ball valve 27 so that the piston 22 and seal valve 26 are able to move downwardly within the body 22 when the actuator is initially depressed until the seal valve 26 closes the hole in the body. Further downward pressure on the actuator will result in an increase in the pressure of the liquid in the chamber 43 and the dispenser will continue to operate as previously described. The hole is positioned so that the air in the air chamber is raised to the desired value before the seal valve 26 closes the hole. When the actuator is released, liquid will be drawn into the chamber 43 until the hole is uncovered by the valve seal 26, after which air will be drawn in to the chamber through the hole. Use of a compressible body or the introduction of air into the liquid pump chamber or the provision of a hole part way down the chamber wall will reduce the capacity of the liquid chamber perhaps by about 30-60%.

Operation of the dispenser 20 modified to allow air to flow from the air pump chamber to mix with the liquid during the initial phase will now be described.

Initial depression of the actuator 21 towards the closure compresses the air chamber and causes the pressure of the air in the air chamber 50 to be raised. Depending on the method used to allow the actuator to move relative to the closure, as discussed above, the pressure of the liquid may be raised simultaneously with that of the air or there may be a delay before the liquid pressure begins to rise. In the present embodiment, the second threshold value at which the tubular valve 53 opens this is set at a relatively low pressure of 0.05 MPa (0.05 bar). This is lower than the first threshold value at which the seal valve opens, which is set at 0.3 MPa (3 bar). Once the air in the air chamber reaches the 0.05 MPa (0.5 bar) threshold value, the tubular valve member 53 opens and air begins to flow into the piston and out towards the outlet orifice 36. After approximately 0.05 seconds, the liquid in the liquid chamber reaches the 0.3 MPa (3 bar) first threshold and the seal valve 26 opens so that liquid begins to flow through the piston bore and the tubular valve member 53 where it meets and mixes with the incoming air. Initially, the pressure of the liquid in the piston bore and the tubular valve member is lower than the pressure of the air in the air chamber by more than the second threshold amount and so the tubular valve remains open, allowing further air to enter the bore 33 to mix with the liquid. However, the pressure of the liquid in the piston bore and the tubular valve member 53 rapidly rises until it approaches and then exceeds that of the air in the air chamber and the tubular valve member is pushed back into contact with the wall of the piston closing off the air hole 52. In the present embodiment, this takes place approximately 0.07 seconds into the spray cycle.

The dispenser then continues to operate as described above in relation to the first described embodiment 20, with the tubular valve opening during the end phase to admit further air into the bore 33 when the pressure of the liquid falls below that of the air in the air chamber by the second threshold amount. The introduction of air into the liquid flow during the initial phase before the liquid reaches it optimal operating pressure at the outlet orifice improves the quality of the spray during this phase, reducing the average droplet size. In addition, the flow of air through the bore 33 and the outlet orifice 36 when the seal valve 26 first opens helps to draw the liquid through the system more quickly which also improves the atomization of the liquid.

The modified dispenser 20 enjoys many of the advantages of the basic dispenser 20. Since air is only introduced into the liquid flow during the initial and end phases when the pressure of the liquid at the outlet orifice is below the normal working pressure, the volume of air required is much less than for an equivalent conventional air/liquid pump dispenser. Furthermore, the air need not be raised to the same pressure as the liquid. Thus, even though the pressure of the liquid in the chamber 43 and the flow path to the outlet orifice 36 is raised to a peak pressure of 0.3 to 0.4 MPa (3 to 4 bar), the air pressure is only raised to about 0.1 to 0.15 MPa (1 to 1.5 bar) at its peak.

The modifications discussed above which enable the air chamber to be compressed to raise the pressure of the air before the outlet valve 26 of the liquid chamber opens can be adopted in any of the embodiments described below in which air is to be introduced into the liquid flow during the initial phase and/or the main phase of the spray cycle.

It is a particular advantage that a dispenser 20 in accordance with the invention can be produced by modifying the design of an existing cylindrical dispenser. In the present example, the turret collar 24 is modified to add the sealing flange 51 and the piston 22 is modified accommodate the tubular valve member 53 and to provide the air hole 52. These changes require only minor alterations to existing tooling. The only other modification that is required is the additional tubular valve member 53. The strength of the return spring may also have to be increased but in many applications this will not be necessary. The minimal changes mean that the existing assembly machinery for the cylindrical dispenser can be used to assemble the new dispenser with only limited changes being required. Furthermore, once assembled, the new dispenser 20 can be handled by the same machinery used for the pre-existing cylindrical pump dispenser. As a result, a dispenser in accordance with the invention can be manufactured, assembled and handled with minimal additional tooling and equipment costs.

It can be seen therefore, that dispensers in accordance with the invention offer improved performance over conventional cylindrical liquid pump dispensers but without many of the disadvantages that have prevented the known air pumps from successfully entering the mass market.

The tubular valve member 53 could be positioned lower down in the bore 33, with the air hole 52 also suitable repositioned. Generally, speaking, the air hole 52 should be positioned adjacent the upper half of the tubular valve member 53 and preferably near to the upper edge as shown. The tubular valve member may be arranged so that only a small circumferential region deforms inwardly so that the air is channelled through a narrow section, reducing the likelihood of the liquid escaping through the hole 52. The strength and resilience of the tubular member 53 determines the pressure differential required across it for it to deform and so the pressure of the air required to open the valve. The region of the tubular valve member 53 below the air hole 52 can be made stronger than that adjacent the air hole so as to resist the flow of air downwardly and to prevent liquid from flowing between the tubular valve member and the piston.

The tubular valve member 53 provides a simple and effective valve arrangement for controlling the flow of air that is cheap to manufacture and easily incorporated in to a modified piston of a pre-existing cylindrical pump arrangement. However, any suitable valve can be used. Furthermore, the air need not be introduced into the piston bore 33 but it could be directed into the liquid flow at any point between the outlet from the liquid pump chamber 43 and the final outlet orifice of the device. So, for example, the air could be directed into the interior of the inner tubular wall member 31, into the chamber 35 or into a swirl chamber by the provision of a suitable flow path connected with the air chamber and a one way valve to prevent liquid from entering the air chamber 50. In some applications, the dispenser has an outlet tube into which the spray orifice 36 directs the spray of liquid. Where this is the case, the outlet of the tube can be considered as the final dispenser outlet and the air from the air chamber may be directed into the tube to mix with liquid and enhance the spray after the spray orifice 36. Since the liquid in the tube will be at a relatively low pressure (at or close to ambient), only a simple one way valve would be required and the air would only ever be at a relatively low pressure just over ambient, say in the range of 0.05 to 0.2 MPa (0.5 to 2 bars). The air could, for example, be directed into the tube through a venturi inlet hole, so that the air is drawn out of the air chamber by the flow of liquid in the tube.

In a conventional cylindrical pump dispenser, the turret collar 5 does not form a seal with the external surface of the piston 3. In a dispenser 20 in accordance with the invention, the turret collar 24 may be arranged so that it seals against the piston 22 to prevent pressurised air from passing from the air chamber 50 between the turret collar and the piston into the region of the body 23 above the seal valve 26 when the actuator is depressed. If a seal is provided, the pressure of the air in the air chamber 50 can be increased by more than would be possible without a seal. If there is no seal between the turret collar 24 and the piston 22, the interior of the body above the seal valve 26 is fluidly connected with the air chamber 50 effectively providing a larger volume double air chamber, which may be desirable in some applications. For example, it can be arranged for air to be introduced into the liquid flow past the seal valve 26 towards the end of the spray cycle by breaking the seal between the seal valve and the body 23. This enables the pressurised air in air chamber 50 and the upper region of the body 23 to flow past the seal valve 26 and enter the bore 33 through the opening 44 following the liquid which is pushed through the bore and outlet nozzle by the air flow. The seal between the seal valve 26 and the body 23 can be broken in any suitable manner. In one embodiment, grooves are provided in the inner the surface of the body which are uncovered by the seal valve 26 as the piston 22 approaches the end of its stroke to fluidly connect the interior of the body above 23 the seal valve with the liquid pump chamber 43. Alternatively, up-stands or projections may be provided on the inner surface of the body which deflect the valve seal to create a flow path from the interior of the body above 23 the seal valve 26 to the liquid pump chamber 43. Because the seal between the seal valve and the body 23 is only broken at or very close to the end of the stroke, the seal will be restored and only liquid will be drawn into the liquid pump chamber 43 during the return stroke. This arrangement is advantageous as it means that the tubular valve member can be omitted, reducing the number of additional components and so reducing manufacturing costs.

Where a seal between the turret collar 24 and the piston 22 is required, it is advantageously produced in a way that minimises the resulting increase in actuation force and return spring strength. For example the seal may be configured so that it is only effective when the actuator 21 is being depressed and not when the actuator 21 is being returned to the start position by the return spring. In one such arrangement, the central hole in the turret collar through which the piston protrudes is larger than the external diameter of the piston 22 and a relatively thin section seal member having an upward conical shape engages the piston. The arrangement is such that as the piston slides down through the hole, the seal member is dragged into close contact with the piston to form a seal. In an alternative arrangement, the turret collar may have a flexible dome portion that is connected to the exterior of the piston to form a seal. In this case, the inner edge of the dome is fixed to the piston and the dome flexes as the piston moves. In a further alternative, the seal may be very week so that the piston moves through it easily. The turret collar 24 can be made wholly from a resilient, flexible material or it may have a substantially rigid main body to which resiliently deformable portions are attached to form the flange 51 and any other required seal or flexible member. In common with most of the components of the dispenser 20, the turret collar is advantageously manufactured from polymeric materials using injection-moulding techniques. Where the turret collar has a rigid main body, bi-injection techniques can be used to form the main body from a first substantially rigid polymeric material and to over mould a second resiliently deformable material onto the main body to form the flange 51, piston seal or other flexible portion.

In some embodiments, the closure 25 only has a single outer flange collar 39 and no inner flange 40. In this case, the turret collar 24 will be thicker than is shown in Figure 2 and the outer wall 30 of the actuator will be received in an annular gap 41 between the outer flange 39 and the turret collar 24 when it is depressed. This arrangement can be adopted in any of the embodiments of the invention disclosed herein.

Some of the alternative arrangements discussed above are incorporated into a dispenser 120 in accordance with a further embodiment of the invention as shown in Figures 3 and 4. The dispenser 120 is essentially the same as the dispenser 20 in accordance with the first embodiment and only those features that are different will be described in detail. The same reference numerals will be used to designate the same or similar features in this and all further embodiments described below. In the dispenser 120, the tubular valve 53 is located in an enlarged bore section at the upper end of the piston so that the upper edge of the tubular valve is generally level with the upper edge of the piston. One or more grooves 57 are provided on the outer surface of the piston at its upper end where it is received in the inner tubular wall portion 31 of the actuator. The groove or grooves 57 extend from a position below the lower end of the inner tubular wall portion 31 to the upper end of the piston where an opening 58 is provided through the piston to connect the, or each, groove 57 fluidly with the liquid flow path where the piston bore 33 opens into the further bore defined inside the inner tubular wall member 31.

An upper end region 53a of the tubular valve member 53 is thinner than the remainder of the valve member and acts as a resilient flap valve for controlling the flow of air through opening 58. In its initial resiliently biased condition, as shown, the upper end region 53a contacts the inner surface of the piston closing off the opening

58 to prevent air from entering the liquid flow path and liquid from flowing in the reverse direction. Air in the chamber 50 is able to enter the groove(s) 57 and impinges on the outer surface of the upper end region 53a of the tubular valve member. When the dispenser is operated, the pressure of the air in the chamber 50 increases and this increasing air pressure acts on the upper end region 53a. When the pressure of the air acting on the outer surface of the upper end region 53a of the tubular valve member is greater then the pressure acting on the inner surface by the second threshold amount or more, the upper end region 53a of the valve member is deflected inwardly so that air from the chamber 50 can enter the liquid flow path. The upper end region 53a of the tubular valve member will revert to its initial resiliently biased configuration to close the opening 58 when the pressure differential across it falls below the second threshold amount.

This alternative tubular valve arrangement could be adopted in the dispenser 20 as described above or in any other embodiments where appropriate.

The dispenser 120 also differs from the first embodiment 20 in that the closure 25 does not have an inner flange 40. Rather, in this embodiment, the turret collar 24 has an inner portion 59 with an outer annular wall region 60, which fulfils the same function as the inner flange 40 in the first embodiment. The turret collar also has an outer portion 61, which includes the seal member 51 for contact with the inner surface of the outer tubular wall 30 of the actuator. In addition, the outer portion 61 also has an inner seal flange 62 that engages with the exterior of the piston 22 to form a seal therewith as discussed above. The inner portion 59 of the turret collar may be manufactured from a substantially rigid material, which may be a polymeric material that is generally rigid once set after moulding. The outer portion 61 of the turret collar may be manufactured from a resiliently flexible material, such as a polymeric material that is resiliently flexible at normal operating temperatures once set after moulding. The inner and outer portions 59, 61 may be separate parts or they may be formed integrally. In one embodiment, the inner and outer portions 59, 61 are formed integrally from polymeric materials using bi-injection techniques in which the resiliently flexible outer portion 61 is over moulded onto the rigid inner portion 59.

As can best be seen in Figure 4, the outlet region of the dispenser 120 has been adapted to provide a swirl chamber or an equivalent "backspinner" means for encouraging the liquid/air to spin about the axis of the orifice 36 before passing through the orifice. Thus, a generally cylindrical projection 63 extends from the inner tubular wall portion 31 of the actuator into the interior of the spray insert 28. The outer end of the projection has a chamfer 64 which abuts a correspondingly chamfered region 65 inside the spray insert. The end surface 66 of the projection is spaced slightly from the inner end surface 67 of the insert so that a swirl chamber (not shown) is defined between the end surfaces. Alternatively, the end surface 66 of the projection may abut the inner end surface 67 of the insert 28 and the swirl chamber defined by means of one or more recess in one or both of the end surfaces 66, 67.

The outer diameter of the projection 63 is smaller that the inner diameter of the insert, so that liquid or a liquid/air mixture flowing through the dispenser outlet region is able to pass between the projection 63 and the insert 28 towards the chamfered regions 64, 65. One or more flow channels are defined between the chamfered regions

64, 65 to direct the fluid into the swirl chamber and are shaped to encourage the fluid to spin about the axis of the outlet orifice 36. The flow channels may be defined by means of grooves in one or both of the chamfered regions 64, 65. The end surfaces 66, 76 may also be shaped so as to promote swirling of the liquid, liquid/air mixture.

A similar swirl chamber arrangement may be provided in the dispenser 20 in accordance with the first embodiment or in any of the other embodiments described herein as appropriate.

The dispenser 120 is otherwise constructed and operated as described above in relation to the first embodiment 20 and may be configured to deliver air into the liquid flow only during the end phase of the spray cycle or it may be adapted to deliver air only during an initial phase of the spray cycle or during both the initial and end phases.

Figure 5 illustrates a further embodiment of a dispenser 220 in accordance with the invention in which the design is modified to eliminate the need for separate tubular valve member. The dispenser 220 is otherwise identical with the first embodiment 20.

In the dispenser 220, the turret collar 24 has a flexible domed upper portion 24a with a central tubular portion 24b which projects upwardly into the actuator 21. The piston 22 is a close sliding fit in the tubular portion 24b and has an air hole 52 which is closed by the tubular portion 24b of the turret collar when the dispenser is in an initial rest position as shown. Two spaced holes 68, 69 extend through the tubular portion 24b of the turret collar and are positioned to align with the air hole 52 in the piston during the initial and end phases only of the dispensing cycle to admit air from the air chamber into the piston. During actuation of the dispenser, the dome 24a on the turret collar initially deflects downwardly becoming inverted as the actuator 21 is depressed. Once the dome 24a reaches its limit of movement, the piston slides within the tubular portion 24a until the air hole 52 is brought into alignment with the upper hole 68 in the tubular portion and air is admitted into the piston bore to mix with the liquid. This occurs during the initial phase of the dispensing cycle just prior to the seal valve 26 opening and/or as the pressure of the liquid in the bore 33 is building. Further movement of the piston 22 relative to the tubular portion 24b moves the air hole 52 to the region between the two holes 68, 69 so that the air hole 52 again covered. The hole 52 remains covered during the main discharge phase until the piston reaches the end of its stroke during the end phase of the dispensing cycle, when the air hole 52 aligns with the second hole 69 in the turret collar tube 24b so that pressurised air is again admitted into the bore 33 to mix with the liquid and travel to the outlet orifice. The dispenser is configured so that air continues to flow after valve seal 26 closes to drive all the liquid out of the piston and the outlet passages on the actuator.

When the actuator 21 is released, the piston and actuator are biased upwardly back to the rest position by the return spring (not shown). During an initial part of the return travel, the tubular portion 24b of turret collar travels with the piston to bring the dome back to its initial configuration. Once the dome reaches its limit of travel, the piston slides through the tubular portion so closing off the air hole 52 in the piston again. The liquid chamber 43 and the air chamber are refilled during the return stroke as described in relation to the previous embodiment 20.

Rather than a dome 24a, the turret collar could be provided with a bellows or any other suitable arrangement, which enables the tubular portion 24b to move with the piston 22 over a limited range. In some embodiments, no movement of the tubular portion 24b is required and the piston can be arranged to slide through the tubular portion 24b to align the piston air hole 52 with the tubular portion air holes 68, 69 at the appropriate times during the spray cycle. Figure 6 shows an embodiment of a dispenser 320 in which the turret collar has a flat upper portion 24c that has no, or only limited, travel when compared to the dome 24a in the previous embodiment. The dispenser 320 is otherwise identical to the dispenser 220 described previously. As described, the dispensers 220, 320 have two holes 68, 69 in the tubular portion 24b of the turret collar so that air is admitted into the piston bore 33 during both the initial and end phases of the dispensing cycle. This will require the dispenser 220, 320 to be modified as discussed above in relation to the first embodiment 20 to enable the actuator 21 to move relative to the closure 25 to raise the pressure of the air in the air chamber 50 before the seal valve 26 opens. In some applications it may advantageous to introduce air into the liquid flow only during one of the initial and end phases. This may be due to a limit in the amount of air that can be provided without increasing the size of the actuator, for example. Usually, air would be added to the liquid flow during the end phase only as there tends to be more problems associated with the reduced pressure in the end phase than in the initial phase, as discussed previously. This can be simply achieved by providing only a single hole 69 in the tubular portion 24b of the turret collar for alignment with the air hole 52 in the piston at the appropriate time in the spray cycle. For example, if the dispenser 220 shown in Figure 5 is to be adapted to admit air into the piston bore 33 only during the end phase; only the lower hole 69 will be provided in the tube portion 24b. Thus during operation as the actuator 21 is depressed, the turret collar dome 24a will initially deflect downwardly to become inverted before the piston begins to slide through the tubular portion 24b. As the piston 22 approaches the end of its actuation stroke, during the end phase, the hole 52 in the piston is brought into alignment with the hole 69 in the tubular portion so that pressurised air is admitted into the bore 33 to mix with the liquid and drive it through the outlet. Air continues to flow from the air chamber 50 into the bore 33 after the seal valve 26 has closed to drive all the liquid through the piston and out of the outlet thus improving the quality of the spray and reducing the tendency to splutter or dribble. Where air is only introduced into the liquid flow during the end phase, no modification of the dispenser to allow relative movement between the actuator 21 and the closure 25 prior opening of the seal valve 26 is necessary.

In Figures 5 and 6, the spray insert 28 has been omitted but may take the same form as that shown in Figure 2 or that as shown in Figures 3 and 4. The dispensers 20,- 120, 220, 320 in accordance with the invention described above are all configured so that air is only introduced into the liquid flow stream during the initial and/or end phases of the dispensing cycle when the pressure of the liquid is below its peak pressure. This is particularly advantageous as it means that the air need not be pressurised to the peak pressure of the liquid and so the actuation force is not as high as would be the case for a conventional air pump. However, the concept of modifying the design of an existing manual pump type dispenser to provide an air chamber can be also be used to provide a dispenser in which air is introduced into the liquid flow throughout the dispensing cycle. This is particularly so where the pump has a relatively low peak pressure for the liquid and/or where a small air to liquid ratio, say less than 10 to 1 and more particularly less than 6 to 1, is required.

Where the air is to be dispensed throughout the spray cycle, or at least the majority thereof, the valve controlling admission of the air into the liquid flow path is arranged so as to allow the air through whilst preventing the liquid from escaping. Any suitable one-way valve could be used. Because the air has to be raised to a higher pressure overall during the spray cycle, the threshold pressure difference at which the air outlet valve opens will usually be set at a higher pressure than in the previous embodiments and the dispenser configured so that valve remains open whilst the fluid is flowing at its peak pressure. Such a dispenser could have a tubular valve member 53 similar to that used in the dispenser 20 described above but adapted so that it opened at a higher pressure, in the region of 0.2 to 0.3 MPa (2 to 3 bar) for example, so that the air does not exit the air chamber until the seal valve 26 opens and the liquid begins to flow or just before, and remains open for the majority of the remaining spray cycle. The valve member 53 may, for example, be configured so that it is distorted by the flow of liquid to open and/or maintain a flow path from the air chamber 50 into the liquid flow. Alternatively, the liquid flow through the bore 33 may be arranged to move the tubular valve member to maintain a flow path from the air chamber 50 into the liquid flow, at least during the main dispensing phase during which the liquid would otherwise close the valve 53. In one embodiment (not show) the tubular valve member 53 is mounted so as to be moved upwards over grooves in the piston or on to an up-stand to open the flow path. Since the pressure of the air in the air chamber needs to be raised up to the same pressure of the liquid before the seal valve 26 is opened, the dispenser will have to be modified as described above in relation to the first embodiment 20 to provide relative movement between the actuator 21 and the closure 25 so that the volume of the air chamber 50 is reduced sufficiently to raise the pressure of the air to the required level before seal valve 26 opens. Any of the methods discussed above in relation to the first embodiment 20 can be adopted.

A dispenser in accordance with the invention in which the air is introduced into the liquid flow over the whole, or majority, of the spray cycle will require a higher actuation force than would be the case when the air is only admitted to the liquid flow path during low pressure phases of the spray cycle and will provide a lower air to liquid ratio during the initial and phases than would be the case with an equivalent dispenser in which air is only introduced during the low pressure phases at the beginning and end of the dispensing cycle. Nevertheless, by using the concept of modifying the design of an existing pump dispenser to incorporate an air chamber, the cost of bringing the modified dispenser pump to market can kept low compared to the cost of developing and manufacturing an entirely new air pump, as it is possible to utilise to a large extent the tooling and handling equipment for the existing dispenser pump with only minimal modifications and additional components being required. Because of the problems potentially caused by higher actuation forces, it is expected that only dispensers having a relatively small discharge volume up to 5mls and more typically up to 2 mis will be arranged to have air mixed with the liquid during the main discharging phase.

The keep the actuation force as low as possible where air is to be mixed with the liquid during the main dispensing phase, the dispenser may be configured to introduce the air into a low pressure part of the fluid outlet passageway. For example, the air may be directed into the centre a swirl chamber through a back wall of the chamber. Where the swirl chamber is formed in the manner shown in Figure 4, a suitable passageway can be provided through the projection 63 and a one-way valve used to prevent the liquid entering the air pump chamber. Alternatively, the air could be introduced into an expansion chamber in the liquid flow path upstream of the outlet orifice 36. For example, the outlet passage could incorporate any of the flow control means disclosed in WOOl 89958 A, and the air could be introduced into the flow control means. As described in WOOl 89958 A, to which the reader should refer for a detailed explanation, the control means may include any one or more of the following: a) an expansion means in which a dimension of the passage transversely to the direction of fluid flow is increased relative to the same dimension of the remainder of the passage; b) inner orifice means in which the dimension of the passage transversely to the direction of fluid flow is decreased relative to the same dimension of the remainder of the passage; c) a multiple channel means wherein at least a part of the passage is divided into from 2 to 12 channels each of which has a decreased dimension transversely to the direction of fluid flow relative to the same dimension of the remainder of the passage; d) a dog leg means in which the flow through the passage is redirected in a direction substantially transversely to the direction of flow in the passage over the length of the means; e) a swirl means wherein rotational flow is induced in the fluid about the direction of flow of fluid in the passage; and/or f) venturi means comprising a narrow passage broadening to a relative wide passage with a narrow air inlet entering the passage near the point at which the passage broadens. In this case, the air could be introduced into one of the control means. The content of WOO 189958 A is incorporated by reference. A further alternative outlet valve arrangement 128 for the air chamber is shown in Figures 12a and 12b. The mounting member is omitted from these drawings. In the arrangement shown, the free end of the piston abuts a pair of ledges 130 in the further bore 131 of the actuator 21 in a known manner. A longitudinally extending groove 132 is provided between the free end region of the piston 22 and the inner surface of the inner tubular wall 31 to allow air to flow from the air chamber towards the free end of the piston. The outer diameter of the free end of the piston 22 has a stepped or tapered portion 133 of reduced diameter and a resiliently flexible O-ring 134 is mounted about the reduced diameter portion 133 to act as a valve member. In it's naturally resiliently biased condition the O-ring forms a seal between the piston and the wall 31 to prevent air from flowing through the groove and entering the further bore. However, under certain circumstances, the pressure of the air acting on the O-ring can distort the O-ring, or part of it, to open a flow path through the groove 130 into the further bore and hence to the outlet 36.

Opening of the valve arrangement 128 depends on the stiffness and/or resilience of the O-ring as well as the relative pressure differential across. Thus the designer can determine a minimum air pressure required to distort the O-ring to open the valve by selecting an O-ring having suitable stiffness. If an O-ring having a suitably low stiffness is used, the valve can be arranged to open during the initial phase of the dispensing cycle when the pressure of the air in air chamber is relatively low but before the liquid begins to flow from the liquid chamber. Once the liquid outlet valve opens, the liquid will flow through the bore 33 of the piston 22 to mix with the air initially. However, as the pressure of the liquid flowing from the liquid chamber to the outlet rises to equal or surpass that of the air in the air chamber, the pressure of the liquid acts on the O-ring to close the valve so that no air is admitted into the further bore during the main phase of the dispensing cycle. During the end phase of the dispensing cycle after the liquid chamber outlet valve has closed, the O- ring will be deflected to open the valve again once the pressure of the liquid acting on the O-ring falls below that of the air in the air chamber. This enables air to flow through the groove 132 again during the end phase to improve the quality of the spray and to clear out the remaining liquid in the outlet passage. It should be noted that the pressure of air flowing from the air chamber will be higher at the start of the end phase than the pressure of the air flowing during the initial phase.

If it is desired that air should only be dispensed during the end phase of the dispensing cycle, then an O-ring having a higher stiffness/resilience can be used, the stiffness being selected so that the pressure of the air in the air chamber is insufficient to defect the O-ring and open the valve during the initial phase but so that the valve will open during the end phase, when the pressure of the air in the air chamber is higher. The valve 128 can also be configured so that it opens once the air pressure has reached a pre-determined value during the initial phase and remains open throughout the remaining dispensing phase by using an O-ring having a suitable stiffness. In this case, it will be necessary to raise the pressure of the air to match or exceed that of the liquid. Again it could be arranged that the flow of liquid during the main phase distorts to O-ring to hold the valve open. However, the valve can be configured so that the flow liquid partially closes or throttles the valve during the main dispensing phase when the pressure of the liquid is at its peak so that a lower ratio of air to liquid is delivered to the outlet during the main phase than during the initial and/or end phases. The stiffness/resilience of the O-ring is dependent on the hardness of the material and the thickness of the ring and can be appropriately determined by varying these parameters.

Rather than mounting the O-ring to the free end of the piston, the O-ring could be mounted within the further bore. For example, the O-ring could be positioned between the ledges 130 and the free end of the piston 22 so that part of it is pushed into the gap between the ledges by the air flowing through the groove to allow the air to flow past it into the liquid outlet passage. Furthermore, whilst an O-ring is particularly effective, any suitable annular, resiliently deformable valve member could be used such as an annular washer of resiliently deformable material. The embodiments of the invention discussed so far have been pumps for dispensing a liquid product, such as a liquor, in the form of a spray. However, the invention is also applicable to dispensers that are configured to dispense a liquid, including gels, as a foam or mousse.

Current foam dispensers tend to mix air and the fluid product at very low pressures, in the region of 0.05 MPa to 0.3 MPa (0.5 to 3 bars) but with high ratios of air to liquid, a ratio of air to liquid in the range of 10:1 to 20: 1 being typical. Due to the high volume of air required to produce these ratios, the known dispensers tend to be large. Often the whole, or a significant part, of the dispenser is located within the neck of a bottle containing the fluid product. Accordingly, the neck region of the bottle must be sufficiently large to contain the dispenser. Furthermore, in the known arrangements, the combination of bottle and dispenser tend to be top heavy and prone to toppling over.

Contrary to the accepted practice, the applicant has discovered that it is possible to generate acceptable foam for mass market applications with lower ratios of air to liquid, in the order of 4:1 to 9:1 and in particular with ratios of 6: 1 to 8: 1. Because a lower volume of air is required, the principles discussed above in relation to the previous embodiments can be adopted to adapt the design of an existing liquid pump dispenser to produce an air/liquid foam dispenser. This is advantageous as a new foam dispenser in accordance with the invention based on the modified design of an existing liquid pump dispenser can be brought to market at considerably lower tooling and equipment costs than would be incurred with the design and manufacture of an entirely new foam dispenser using conventional liquid to air ratios. Furthermore, a foam dispenser in accordance with the invention will tend to be smaller than an equivalent conventional foam dispenser, meaning that it can be accommodated in a bottle having a smaller neck region.

Figure 7 shows a further embodiment of the invention, which illustrates how a conventional existing cylindrical liquid pump design can be modified into a foam dispenser 420. The general construction of the dispenser 420 is similar to the previous embodiments and it has a modified turret collar 24 with a seal flange or bell 51 arranged to contact the inner surface of the outer wall 30 of the actuator 21 to define an air chamber 50 within the actuator.

An over cap 72 is mounted over the actuator 21 and has an outlet spout arrangement 73. Rather than having an over cap, the actuator 21 can be modified to included an integral outlet spout 73. The outlet spout defines a first mixing chamber 74 into which liquid product is sprayed from the constricted nozzle orifice 36 in the spray insert 28. An air inlet passage 75 fluidly connects the air chamber 50 with the mixing chamber 74 so that the air and liquid are mixed in the chamber 74 before passing out through a narrow opening or throttle 76 into an outlet foam passage 77. At least one mesh screen 78 extends across the outlet foam passage to filter the foam and improve its quality in a known manner. Although only one mesh screen 78 is shown in Figure 7, in many applications two or more screens will be used as this produces an improved quality of foam.

A swirl chamber (not shown) will usually be provided prior to the spray nozzle orifice 36, though in some applications acceptable foam can be generated using only a spray orifice with no swirl chamber. The swirl chamber can be formed by means of a projection 63 within the insert 28, as described above in relation to the second embodiment 120 and as shown in Figure 4. Rather than a swirl chamber as such, any equivalent means for causing the liquid to spin about the axis of the orifice 36 prior to passing through the orifice can be used.

In the present embodiment, the dispenser is configured so that the liquid is delivered from its pump chamber to the spray orifice 36 at a pressure in the region of 0.1 to 0.4 MPa (1 to 4 bar). In general, the higher the pressure of the liquid the better the quality of foam produced. Once the liquid passes through the spray orifice 36 into the mixing chamber 74, its pressure falls. Where the pump pressure is 0.4 MPa (4 bar), the pressure of the liquid in the chamber 74 may be in the region of say 0.2 MPa (2 bar). In addition, because the liquid does not occupy the whole of the chamber, the pressure in the chamber is lower than that of the liquid entering the chamber, though it is still above ambient in order to drive the foam out. Because the air from the chamber 50 is being introduced into the liquid flow downstream of the spray orifice and swirl chamber (where one is provide) where the pressure is low, the air need only be pressurised to just over ambient, say in the region 0.01 MPa to 0.05 MPa (0.1 bar to 0.5 bar). The precise air pressure may vary depending on the application and the air may be pressurised by up to approximately 0.1 MPa (1 bar), which is particularly advantageous where the liquid pressure upstream of the spray orifice is towards the higher end of the range mentioned above. Because the air is being directed into a low- pressure part of the liquid flow path, no pre-compression outlet valve is required at the air passage 75, which tends to act like a venturi hole so that the air is automatically drawn into the mixing chamber 74 from the air chamber by the liquid flow. The design of the chamber 74 and the passage 75 can be configured to encourage the venturi effect. However, a one-way valve (not shown) may be required to prevent liquid from entering the air pump chamber.

In operation, when the actuator 21 is depressed, the liquid in the liquid chamber 43 is pressurised to bring the liquid to the desired operating pressure, at which time the seal valve 26 opens and the liquid flows through the piston 22, the swirl chamber (if present), the spray orifice 36 and into mixing chamber 74. Once the valve 26 opens, downward movement of the actuator 21 reduces the volume of the air chamber 50 so increasing the pressure of the air contained in the air chamber 50. Air from the chamber passes through the passage 75 into the mixing chamber 74 where it mixes with the liquid. The air may be drawn through the passage 75 due to the venturi effect of the liquid flow through the mixing chamber 74 or due to the increased pressure of the air in the chamber 50 or a combination of the two. The liquid/air mixture passes through the throttle 76 into the outlet foam passage 77. The mixture passes along the passage through the mesh screen filter(s) 78 where the foam is refined before passing through the outlet 79 of the passage 77.

Once dispensing is complete, the piston 22 and actuator 21 are biased back to the start position by a return spring closing the seal valve 26 and drawing a fresh charge of liquid into the liquid pump chamber 43 and a fresh charge of air into the air chamber 50, as described in relation to the previous embodiments.

Introducing the air into a low pressure region of the liquid flow path has the advantage that the overall actuation force is kept low because the air in the chamber

50 does have to the raised to the same pressure as the liquid. The position of the air passage 75 can be varied and, for example, may be arranged to direct air into the outlet foam passage 77 downstream of the throttle in some cases.

Because of the limitations of converting an existing liquid pump design, the volume of air available in each actuation will typically be 20 mis or less and usually 18 mis or less with a maximum liquid discharge of 2.5 mis and usually 2 mis or less. Whilst it is advantageous to mix the air and liquid in a low-pressure region of the liquid flow path to the outlet 79, the air could be introduced upstream of the spray orifice 36 and swirl chamber (where provided). In this configuration, it is necessary to raise the pressure of the air so that it matches that of the liquid in the high-pressure part of the flow path and a pre-compression one-way outlet valve will be required at to control the flow of air from the air pump chamber. This arrangement is most advantageously used where the liquid pressure is relatively low, say in the region of 0.1 MPa (1 bar), though it could be used where the liquid pressure at the spray orifice is in the range of 0.06 MPa to 0.3 Mpa (0.6 to 3 bar) or more.

Where the air is to be introduced into a high pressure part of the liquid flow path, it is necessary to allow the actuator 21 to move relative to the closure 25 to reduce the volume of the air chamber 50 raising the pressure of the air to the desired threshold value before the seal valve 26 opens, as with the modified version of the first embodiment 20 described above. Any of the methods of achieving this described above in relation to the previous embodiments can be employed. Where the air is introduced into a low pressure region of the liquid flow path it and need only be raised to a relatively low pressure when compared with the pressure of the liquid in the liquid chamber 43, the necessary air pressure can be generated by using a small diameter air passage 75 which restricts the air flow and creates a back pressure, raising the pressure of the air in the air chamber 50. In this case, it will usually not be necessary to reduce the volume of the air chamber before the seal valve 26 opens. In addition, the reduction in volume of the air chamber 50 after the seal valve 26 has opened will push the air through the air passage 75 raising the air to the required pressure whilst the liquid is being discharged. As discussed above, the venturi effect of the liquid flow can also be used to draw the air through the air passage 75.

Figures 8 and 9 show a further embodiment of a foam dispenser 520 in accordance with the invention. The dispenser 520 is in essence similar to the previous embodiment 420 though there are a number of variations which will be described. In the dispenser 520, the outlet spout 73 is formed as an integral part of the actuator 21 rather than being provided as part of an over cap. In addition, the outer wall 30 of the actuator is located on the outside of the annular flange 39 on the closure 25. In this instance, the closure 25 only has a single annular flange 39, which is equivalent to the outer annular flange 39 as described in relation to the first embodiment 20. The closure could, however, have two annular flanges, in which case the outer wall 30 would be arranged to locate about the outside of the outer annular flange. In order to form an air chamber 50 in the actuator 21, a seal member 79 is mounted to the turret collar 24. The seal member has an inner seal 62 that engages on the outside of the piston 22 and an outer seal 51 that engages on the inner surface of the outer wall 30 of the actuator. Between the inner and outer seals 62, 51, the seal member 79 has a body portion with a downwardly depending annular flange 80 which locates in the gap between the turret collar 24 and the flange 39 of the closure 25. The seal member 79 thereby effectively closes of the open lower end of the actuator to create the air chamber 50. The seal member 79 could be formed integrally with the turret collar 24 rather than as a separate component. By arranging for the outer wall 30 of the actuator to locate on the outside of the flange 39, the volume of the air chamber 50 is larger than would be the case if it located on the inside as in previous embodiments. This is advantageous in applications in which a larger volume of air is required and can be adopted in any of the embodiments described, including those dispensers that are configured to produce a spray rather than foam.

The dispenser 520 is provided with a twist lock arrangement to prevent accidental actuation. The twist lock is formed by means of an up stand 81 on the seal member 79. The up stand 81 is configured so that when the actuator is in a first locked position, as shown in Figure 8, a tubular portion 83 of the actuator which extends generally horizontally (as shown) between the inner and outer annular walls 31, 30 and which houses part of the outlet passage from the piston 22 to the spout 73 contacts the up stand to prevent the actuator being depressed. In order to actuate the dispenser 520, the user must first rotate the actuator 21 to an unlocked position in which the up stand 81 does not make contact with the tubular portion 83 of the actuator. A similar twist lock arrangement can be adopted in any of the embodiments disclosed herein.

In the dispenser 520, a swirl chamber is formed immediately up steam of the spray orifice 36 by means of a projection 63. The projection 63 is formed as part of the actuator and engages in the spray insert 28 in a manner similar to that described above in relation to the second embodiment 120 and as shown in Figure 4. The dispenser 520 in accordance with the present embodiment has a single upper spring 85 that acts both as a return spring and to control the opening of the seal valve 26. The spring 85 is a coil spring having a larger diameter upper portion 86 and a smaller diameter lower portion 87 with a conical tapering region 88 in between. The exterior of the piston within the body 23 is correspondingly shaped having a larger diameter portion 22b above a smaller diameter portion 22a connected by means of a conical or tapered region 22c. The spring is positioned about the piston so that its larger diameter portion 86 locates about the larger diameter portion 22b of the piston and its smaller diameter portion 87 locates about the smaller diameter portion 22a of the piston with the conical or tapered region 88 of the spring contacting the tapered region 22c of the piston. The upper end of the spring locates tightly about a flange 89 on the turret collar 24 so that it is fixed in position, whilst the lower end of the spring engages an upper surface of the seal valve 26 so as to bias seal valve downwardly bringing the flap 46 into contact with a stop 22d on the piston. In this position, the flap 46 seals against the piston to prevent fluid from entering the opening 44 through the piston wall into the bore 33.Rather than a taper 88, the piston may have a step between the larger and smaller diameter portions of the body and the spring shaped to engage under the step.

Operation of the spring 85 and the seal valve 26 will now be described.

When a force is applied to depress the actuator 21, the force is tends to move the piston 22 and the seal valve downwardly to reduce the volume of the liquid pump chamber 43. However, because the ball valve 27 is closed and the liquid in the chamber is substantially incompressible, downward movement of the seal valve 26 is prevented. Accordingly, the piston 22 is moved downwardly through seal valve. Because the conical region 88 of the spring is in contact with the conical region of the piston 22c, downward movement of the piston compresses the lower smaller diameter portion 87 of the spring. This increases the spring force applied to the seal valve and hence the force applied to the liquid in the chamber 43 by the seal valve, raising the pressure of the liquid in the chamber. At the same time, the upper, larger diameter region 86 of the spring is stretched.

The piston continues to move downwardly relative to the seal valve 26 until the opening 44 in the piston is uncovered and the liquid is able to flow through the piston bore 33 to the outlet in the usual manner. Continued depression of the actuator

21 causes the piston 22 to move downwardly with the seal valve 26 also moving downwardly due to the spring force applied by the smaller diameter portion 87 of the spring thus forcing the liquid in the chamber to flow through the opening 44 to the outlet. At the same time, downward movement of the actuator 21 relative to the closure reduces the volume of the air chamber 50 forcing air through the passage 75 into the outlet nozzle as will be described in more detail below.

When the actuator 21 reaches the limit of its downward travel and all the liquid in the chamber 43 has been displaced, as shown in Figure 9, the seal valve 26 engages with a step 90 in the body and is held in contact with the step by the lower, smaller diameter portion 87 of the spring. At this stage, the upper, larger diameter portion 86 of the spring is stretched and applies a restoring force to the conical region 22c of the piston. When the user releases the actuator 21, the upper, larger diameter portion 86 of the spring acts on the conical portion 22c of the piston to pull the piston upwardly and return the piston 22 and actuator 21 to the start portion. Initially as the piston begins to move upwardly, the seal valve 26 is held in contact with the step 90 by the lower, smaller diameter portion 87 of the spring 85 so that the piston is pulled upwardly through the seal valve 26 until the stop 22d on the piston contacts the seal valve 26. At this point, the opening 44 in the piston is closed by the flap 46 on the seal valve and the seal valve 26 is constrained to move upwardly with the piston. As the piston and seal valve 26 move upwardly within the body to the start position, a fresh charge of liquid is drawn into the chamber 43 through the ball valve 27. At the same time, the upward movement of the actuator 21 increases the volume of the air chamber 50 so that a fresh charge of air is drawn into the air chamber past the seal 51, in a similar manner to that described in relation to the previous embodiments.

The spring 85 and seal valve 26 arrangement used in this embodiment 520 can be used in any of the other embodiments 20, 120, 220, 320, 420 as described herein. Alternatively, a separate return and valve control spring arrangement can be used as described above in relation to the prior art dispenser 1. The outlet spout 73 in the dispenser 520 can be provided with a foam passage

77 in which one or more mesh screens 78 are located to refine the foam, in a manner similar to the previous embodiment as shown in Figure 7. However, in an alternative arrangement as shown in Figures 8 and 9, the screen filter arrangement is replaced by a plug 91 of open celled foam or an equivalent three dimensional mesh in the outlet. In the present embodiment, the plug 91 is held in an insert 92 that locates in a bore 93 of the spout. The insert 92 has a central bore 94 that aligns with the spray orifice 36 to define the foam outlet passage 77. At the inlet end, the bore 94 of the insert tapers at 94a to direct the liquid sprayed through the orifice 36 into the main portion of the bore 94. The bore 94 has an enlarged diameter central region 95 in which the plug is located. A locking ring 96 is moulded integrally with the actuator 21 and is connected with the spout by means of a flexible tab 97. The locking ring is a tight fit in the bore

93 of the spout and is inserted in the end of the bore 93 to hold the plug insert 92 in place after the insert 92 has been assembled into the spout 73.

The air chamber 50 is fluidly connected with the tapered inlet end of the bore

94a in the foam plug insert 92 by means of the air passage 75. During actuation of the dispenser 520, air is drawn or pushed through the passage 75 to mix with the liquid as it leaves the spray orifice 36. The mixture of air and liquid then passes along the bore

94 where it foams and passes thorough the plug 91 before exiting the nozzle through the final outlet, which in this case is defined by the inner opening of the locking ring 96. The foam plug 91 acts in a similar manner to the mesh screens 78 to filter and refine the foam as it passes through but the plug is easier to manufacture and assemble into the dispenser nozzle than a screen mesh arrangement. This reduces manufacturing costs, which is an important consideration in the field of mass-market foam dispensers. ^ In tests, it has been found that a plug 91 made from open celled foam in which the average cell sizes, in situ, are in the range of 0.3 to 0.6 mm dia. are effective, with a foam having average cell sizes in the range of 0.37 to 0.5 mm dia. being particularly preferred. In its relaxed state, the foam used in the trials had cell sizes between 0.4 and lmm dia., giving an average cell size of about 0.7 mm dia. When formed into the plug 91, the open celled foam was compressed so that the average cell size was reduced to the range specified. Two different foam plugs were tested as follows:

1) Initial foam plug size 7mm X 10mm dia. located in a chamber 6mm x 6mm dia. (compression ratio 2.9)

2) Initial foam plug size 4.5mm x 12 mm dia. located in a chamber 5mm x 3mm dia. (compression ratio 6.9) The foam used in the trials had a density of 22 Kg/m³ with approximately 14 cells per cm in a relaxed condition. In the compressed condition, plug 1 had approximately 20 cells per cm whilst plug 2 had approximately 27 cells per cm.

However, the foam need not be compressed provided it has the required density and average cell size.

The plug 91 will typically have a length in the range of 3 to 10 mm and a diameter in the range of 3 to 10 mm. Two or more foam plugs 91 could be used. The plug need not be mounted in an insert 92 but could be fitted directly into the nozzle.

Any suitable open celled foam may be used provided that it is not water absorbent. Whilst it is convent for the plug to be generally cylindrical, it can be suitable shape.

A plug of open celled foam 91 or another 3D mesh as described above can be used in any type of manual pump foam dispenser instead of a conventional mesh screen arrangement and so is not limited to use with dispensers in accordance with the invention as otherwise described herein. Accordingly, this arrangement may be claimed independently. In addition, it has been found that use of a foam plug or 3D mesh in combination with lower ratios of air to liquid, in the order of 6:1 to 8:1, make it possible to produce foam from an aerosol dispenser, in which a liquid or gas propellant is present inside the container to pressurise the contents. Typically, the outlet nozzle of the aerosol dispenser will comprise a swirl chamber adjacent a spray orifice and the plug or 3D mesh is positioned in an outlet tube following the spray orifice. Air or gas from the propellant is mixed with the liquid product. This would normally be carried out in the aerosol valve by means of a vapour phase tap prior to the swirl. This arrangement may also be claimed independently.

It has been found that the performance of the plug 93 is enhanced if the foam is passed through two or more distinct regions of the open celled material, with adjacent regions region being separated by a gap. This acts in the same manner of spaced meshes, with the foam forming in the gap and being further refined as it passes through the next region of open celled filter material. This arrangement can be provided by using two or more discrete plugs 91 in the outlet spout with a gap between each plug. However, in a particularly convenient arrangement, a single plug of material can be provided with one or more slots or openings in which none of the open celled material is present to form a gap between adjacent regions of the filter material. The slots or openings are positioned so that most of the foam passing through the plug passes through at least one gap. Figures 13a, 13b and 14a, 14b illustrate two embodiments of a modified plug 91 ', 91" which each have two enlarged cavities or slots 214 to form gaps in the filter material spaced along its length. The gaps 214 are positioned so that they extend across at least a central third region of the cross sectional area of the plugs through which a majority of the liquid/foam passing through the plug will flow. The gaps 214 divide the pug in to separate filter portions along its length. In the plug 91 ' as shown in Figures 13a and 13b, two slots 214 extend from opposite sides of the plug across the central region. In the plug 91 " shown in Figures 14a and 14b, cavities 214 are formed so as to extend only across a central region through which the majority of the foam will pass. The number and shape of the slots or cavities 214 can be varied to suite the application. The modified plugs 91 ', 91 " are inexpensive to manufacture and can be easily inserted into the outlet passage but have been found to highly effective. These modified plugs 91 ', 91" can be used in any of the foam dispenser embodiments disclosed herein.

Figure 10 shows a further embodiment of a dispenser 620 in accordance with the invention. The dispenser 620 is very similar to the dispenser 520 of the previous embodiment, except for the arrangement for sealing the actuator 21 to the closure 25 to produce an air chamber 50.

In the dispenser 620, there is no sealing member mounted to the turret collar 24. Rather a seal member 99 is formed at the lower end of the outer wall 30 of the actuator 21 for contact with the outer surface of the flange 39 on the closure 25. As can be seen best in the detailed view, the seal member 99 comprises a resiliently deformable flap 99 which angles inwardly and upwardly into contact with the flange 39. When the actuator is depressed, the flap 99 is biased into contact with the flange 39 by its resiliency. In addition the increasing air pressure inside the chamber 51 acts on the inner surface of the flap 99 helping to maintain the seal. When the actuator 21 is returned to the start position, the pressure inside the air chamber 50 falls as the volume of the chamber increases, allowing ambient air to deflect the flap away from the flange to enter the chamber. As shown in chain dotted lines in the inset detailed view in Figure 10, the flap 99 may be moulded in a position in which it projects generally in line with the outer wall 30 of the actuator and folded inwardly during assembly of the dispenser. The hinge type connection between the flap 99 and the wall 30 is resilient so that the flap is resiliently biased into contact with the flange 39 when assembled.

In this embodiment, the up stand 81 for the twist lock is provided on the turret collar 24 which also carries an inner seal member 62 for contact with the outer surface of the piston 22. The arrangement in which an up stand is provided as part of the turret collar for a twist can be adopted in any of the embodiments herein. Indeed, a twist lock arrangement may be provided on any of the embodiments disclosed by forming an up stand on the turret collar or a separate component mounted to the turret collar which contacts a portion of the actuator or a component mounted to the actuator to prevent the actuator being depressed when it is in a locked position. The arrangement being such that the actuator can be rotated to an unlocked position in which the portion of the actuator or other component does not contact the up stand when the actuator is depressed so that the dispenser can be actuated.

In all other respects, the dispenser 620 is the same as the previous embodiment 520 described above to which the reader should refer for details.

Although it is not necessary to use a pre-compression valve to control the flow of air from the air chamber 50 into a low pressure region of the liquid flow path, it may be advantageous to provide a one-way valve in association with the air passage 75 to prevent foam or other liquid being drawn into the air chamber 50 when the actuator recovers to the start position. Figure 11 illustrates an alternative actuator 21 for use with any of the dispensers as shown in Figures 7 to 10. In the actuator 21 as shown in Figure 11, the spray orifice and swirl chamber are located close to the center of the actuator and the air passage 75 is directed straight up into the outlet passage 77. The insert 92 which holds foam plug 91 has a thin flange 100 of flexible material at its inner end which overlies the air passage 75 where it opens into the outlet passage 77. The flange is resiliently flexible and is deflected away from the surface of the passage 77 to admit air into the outlet passage during the dispensing cycle. When the actuator 21 returns to the start position and air is drawn into the air chamber 50, the flange covers the air passage 75 to prevent foam being drawn through the air passage 75 into the air chamber. Whilst any suitable one-way valve arrangement can be used, in the present embodiment, a valve flap is conveniently formed as an integral part of the foam plug insert 21. In this case, the insert 92 may be formed wholly of a suitably flexible material or a flexible flange can be over moulded onto a substantially rigid part of the insert to form the valve flap. The valve flap could of course be provided separately from the insert 92, for example as a tubular valve inserted into the bore 93. In a further modification, the insert 92 is held in position in the actuator by means of a ridge 101 on outside of the body of the insert which locates in a corresponding groove 103 in the bore 93 of the actuator.

In the foam dispenser embodiments described above in relation to Figures 7 to 11, the liquid is sprayed through a constricted outlet nozzle orifice 36 which is configured to break the liquid up into droplets and preferably to form a conical spray. However, in some applications where the liquid is viscous and/or where there is insufficient distance between the nozzle and the screen or plug filter, a conical spray may not be formed and the liquid will jet through the nozzle 36 adversely affecting the quality of the foam produced and may, in certain circumstances, prevent any foaming from taking place. In order to address this problem, it has been found that good quality foam can be produced by using one or more fan jets to produce a fan shaped spray rather than a cone shaped spray. This has been found to be effective with viscous fluids or in other circumstances where a cone shaped atomised spray could not be formed. The fan jet nozzle may be in the form of an elongate or eye-shaped orifice. In a further alternative arrangement, a flood jet nozzle is used to create a sheet of liquid in the mixing chamber 74 rather than an atomised spray as such. This has also been found to be effect in producing high quality sprays, in particular with viscous liquids. Figures 15a and 15b illustrate one embodiment of a flood jet nozzle which is being used in combination with a modified plug 91' of expanded foam, though this is not essential. In this embodiment, the liquid is introduced into the chamber 74 through a lateral opening 218 and is directed on to a curved ramp 221 which turns the direction of movement of liquid through an angle so that it is directed on to the plug 91'. The ramp 221 may turn the liquid through an angle of approximately 90° but the angle could be anywhere between 60° and 120°. This creates a fan shaped sheet of liquid, which in the present embodiment is aligned substantially vertically when the dispenser is upright. The ramp 221 may have side walls to prevent the fan spreading and could be formed as a groove in the end wall region 222. The width of the ramp is selected as appropriate for any particular application. The lateral opening 218 and the ramp 221 are positioned substantially centrally along a diameter of the circular end wall 222. Air is introduced into the chamber 74 through a series of orifices 224 in an axial direction through the end wall 222 of the passage to mix with the liquid but the air can be introduced in any direction and in any suitable position. The surface of the ramp 221 may be smooth or it may be shaped or textured, as illustrated at 226 in Figure 16, to break up the fan of liquid into droplets. In a further alternative the ramp 221 could be constructed so that it moves when the liquid impacts on it to break up the fan. The dispenser outlet could be provided with more than one liquid inlet 218 and ramp 221. A further alternative embodiment is illustrated in Figure 17 in which the liquid is introduced into the chamber 74 though an inlet passage 228 which is aligned axially with the outlet spout and the ramp 220 is arranged to direct the fan on to a side wall of the chamber 74 so that it is deflected off the wall onto the plug 91'.

The above embodiments all produce a fan shaped sheet of liquid which may be broken up in the chamber 74. Figures 18a and 18b illustrate an embodiment in which a flood jet nozzle 36 is arranged to produce a conical sheet of liquid. In this embodiment, the liquid flow passage has a conically divergent region 248 through which the liquid flows into the chamber 74. A flow divider 250 is suspended centrally within the conically divergent outlet region 248 by means of three links 252. The flow divider has a conical region 254 which locates within the divergent outlet region 248 so that the outer surface of the conical region 254 is spaced from the surface of the passage to define an annular frusto-conical passage 256 about the divider through which the liquid flows to enter the chamber 74. The outer end of the flow divider is hemispherical in this embodiment but can be any suitable shape. The liquid flowing through the annular frusto-conical passage 256 about the divider passes through the gaps between the links 252 to form a generally conical sheet of liquid in the chamber 74 which is directed on to a plug 91, which can be of any of the types described above or may be replaced by any other suitable screen or filter for refining the foam. Air is introduced separately into the chamber 74 to mix with the liquid by any suitable means, including any of those described above in relation to Figures 15 to 17. This arrangement differs from a cone spray nozzle as the liquid is not formed into a spray as it passes through the jet nozzle but forms a conical sheet of liquid. This has been found to be particularly effective at producing good quality foams with viscous liquids which are unsuitable for producing a conical spray in the outlet of a foam dispenser of the types used to dispense consumer products.

In most of the embodiments shown, the outlet nozzle is contained within the actuator 21. However, the invention is also applicable the dispensers in which the outlet nozzle is housed in a separate spout on the actuator. Where the spout is large, an additional tube may be located in the spout to house the nozzle.

The presence of a pre-compression outlet valve to control the flow of liquid from the liquid pump chamber is advantageous as this ensures that spraying is commenced when the pressure of the liquid is sufficiently high to create a good quality spray. Ideally a pre-compression valve should be located close to the outlet nozzle or orifice 36 so that the pressure at the orifice builds very quickly when the valve opens and so that there is a minimum of liquid downstream from the valve continuing to flow through the outlet orifice when the valve closes. To this end, a pre- compression outlet valve may be located in the flow path from the liquid pump chamber close to the nozzle and configured to open to allow liquid to be dispensed only when the pressure of the liquid at the valve is above a minimum pre-determined value required to generate an acceptable quality spray in the particular application.

Figures 19a and 19b illustrate one embodiment of a pre-compression valve

260 close to spray orifice 36. The valve 260 comprises a resiliently deformable valve member 262 having a cylindrical body portion with larger diameter flange 264 at one end. The valve member 262 is located in a bore 266 forming part of the liquid flow path immediately upstream of the spray nozzle or other constricted orifice 36 with the opposite end of the body from the flange being received in the insert 28 in which the orifice is formed. The end of the body closest to the orifice abuts an inner face of the insert to define a swirl chamber 268 between the body and the insert. In this regard, the valve member takes the place of the projection 63 in the arrangement described above in relation to Figure 4. Grooves (not shown) on the end face of the body and/or on the inner surface of the insert form channels for directing the liquid into the swirl chamber. A seal land 270 projects inwardly from the surface defining the bore 266. The valve member 262 is resiliently deformable. In its initial resiliently biased configuration as shown in Figure 19b, the flange 264 is aligned with and contacts the land 270 to form a seal preventing the liquid from flowing past the valve member to enter the swirl chamber and the orifice. When the dispenser is actuated and liquid is delivered under pressure from the pump chamber, the liquid contacts the inner end 272 of the valve member 262 and compresses the valve member against the insert 28. As the pressure of the liquid acting on the valve member increases, the valve member becomes more compressed until eventually the flange 264 is moved off the land 270, as shown in Figure 19a, to open a flow path to the swirl chamber and the orifice 36. The valve member 264 is constructed so that the flow path is opened only when the pressure of the liquid reaches a desired first threshold value above ambient required to produce an acceptable quality spray at the orifice. When the pressure of the liquid falls off during the end phase, the valve member 264 recovers its initial shape and recloses the flow path once the pressure of the liquid falls below the threshold.

Because the valve 260 is located close to the spray nozzle 36, the build up of pressure at the spray nozzle 36 is very quick when the valve 260 opens reducing the length of the initial phase of the dispensing cycle. Similarly, once the valve closes 260 there is very little liquid remaining in the passage downstream of the valve to continue to flow through the outlet so that the end phase of the dispensing cycle is also shortened. This results in a very sharp beginning and end to the spray cycle with little spluttering or dribbling.

The valve 260 may be the only pre-compression valve used to control the flow of liquid from the liquid chamber or it may be used in addition to a pre-compression outlet valve located closer to the liquid chamber. Other types of valve could be used. For example an O-ring valve could be used in conjunction with the projection 63 in the arrangement shown in Figure 4. In addition, air from the air chamber can be introduced into the liquid flow path in the vicinity of the valve member 264 which can be arranged to also act as an air release valve. Whilst this arrangement is most beneficial in spray dispensers, it can also be adopted in foam dispensers with the valve being located adjacent the constricted orifice. A pre-compression valve adjacent the orifice the 36 can be incorporated into any of the embodiments disposed herein.

In the embodiments described, the air chamber 50 is formed within the actuator 21. However, in some known liquid dispensers, the actuator is spaced from the closure even when fully depressed. In such cases, a bellows or other suitable structure can be provided between the actuator 21 and the closure 25 or the turret collar 24 to define an air chamber. Indeed any suitable arrangement can be adopted for providing an air chamber between the actuator and the closure and turret collar or other components that mount to the bottle or container.

In the embodiments described, the dispenser outlets are aligned generally perpendicular to the longitudinal axis of the dispenser, so as to extend generally horizontally when the dispensers are upright. However, the invention is not limited to this arrangement and the outlets can be arranged at any suitable angle. For example, the outlets could be aligned vertically, in line with the longitudinal axis of the dispenser. In this type of arrangement, the outlet nozzle orifice 36 and the swirl chamber (where provided) can be located in or on the upper end of the piston rather than in the actuator itself. Where the dispenser is a foam dispenser, a vertically extending outlet nozzle may be provided in which the mesh or plug type filters are located. The outlet nozzle will usually be formed as part of the actuator but this is not essential.

The invention is also applicable to dispensers which have a trigger handle which passes over the top of the actuator and down a front of the dispenser. The trigger handle is configured so that pulling the trigger pushes the actuator down to actuate the dispenser. It will be appreciated that such known liquid dispensers can also be adapted to form an air or foam dispenser in the manner describe herein. The principles disclosed herein can be applied with particular advantage in modifying the design of existing liquid only pump dispenser to produce an air/liquid spray or foam dispenser that can be manufactured utilising many of the tools used to manufacture the original dispenser and which can be handled using the same machinery. Due to the constraints imposed by using a pre-existing design, the resulting dispensers may not be as effective as a purpose designed and manufactured air/liquid dispensers. However, the resulting dispenser will produce better quality sprays than the original liquid only dispenser or will enable the dispenser to be modified for use as a foam dispenser. Due to the much lower initial tooling and machinery costs involved in adapting an existing dispenser compared with the introduction of an entirely new dispenser, it is expected that dispensers in accordance with the invention will be more readily taken up in mass market fields where cost is an important factor.

As discussed above in relation to the various embodiments shown, there are numerous ways in which dispensers in accordance with the invention can be arranged to vary the ratio or air to liquid over the dispensing cycle. In arrangements were the air is introduced into a low pressure region of the liquid flow path to the outlet, the increased back pressure of the liquid flowing through the outlet passageway arrangement can be used to reduce the flow rate of the air during the main phase of the dispensing cycle. However, it is expected that in most applications at least a simple one-way valve will be required in the outlet flow path from the air chamber to prevent liquid from enter the air chamber. In this case, the dispenser can be configured so that the one-way air valve is closed during the main phase by the pressure of the liquid in the outlet passageway to prevent any air being mixed with the liquid. Alternatively, the dispenser can be configured so that the one-way air valve is throttled by the back pressure of the liquid so that the flow of air is reduced during the main phase to reduce the ratio of air to liquid. In other arrangements the air release valve can be a pre- compression valve which is configured to open only when the pressure of the air reaches the particular threshold value (the second threshold) above ambient. As the pressure of the air in air chamber is higher during the end phase than during the initial phase, the air chamber outlet valve threshold pressure can be set so that air is added to the liquid during both the initial and end phases or only during the end phase. Alternatively, the pre-compression valve can be arranged to stay open over the whole or the majority of the dispensing phase with the valve being partially closed or throttled during the main phase so that a reduce flow of air is added to the liquid. Whereas the invention has been described in relation to what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the arrangements disclosed but rather is intended to cover various modifications and equivalent constructions included within the spirit and scope of the invention.

Claims

1. A pump dispenser for mounting to a container for holding a liquid to be dispensed, said dispenser comprising a liquid pump for pumping liquid from said container, an air pump for pumping air to be dispensed with the liquid and a common actuator to simultaneously actuate the liquid pump and the air pump, the dispenser having an outlet and a fluid passageway arrangement for fluidly connecting the liquid pump and the air pump with the outlet, in which the dispenser comprises a mounting member for mounting the dispenser to the container, a generally cylindrical body located within the mounting member for projection into the container and a turret collar for positioning the body within the mounting member, the dispenser further having a piston movably mounted within the body, a seal member operative between the piston and an inner surface of the body to define a liquid pump chamber within the body, the actuator being mounted to, or operatively connected with, the piston, the dispenser having means for defining an air pump chamber within the actuator, in which the dispenser outlet passageway arrangement comprises at least one constricted orifice through which liquid from the liquid pump chamber is passed.

2. A pump dispenser as claimed in claim 1, in which the dispenser is configured so that when mounted to a container, all, or a significant majority, of. the air pump chamber is located externally of the container.

3. A pump dispenser as claimed in claim 2, in which the dispenser is configured so that when mounted to a container, the whole of the air pump chamber is located within the actuator about an exposed portion of the piston externally of the container.

4. A pump dispenser as claimed in any one of the previous claims, in which the dispenser comprises an outlet valve arrangement for controlling release of the liquid from the liquid pump chamber and air from the air pump chamber during a dispensing phase when the dispenser is actuated, the outlet valve arrangement being configured such that the ratio of air to liquid dispensed varies over the course of the dispensing phase during each actuation.

5. A pump dispenser as claimed in claim 4, in which the outlet valve arrangement is configured such that the ratio of air to liquid dispensed is higher during at least one of an initial and an end phase of the dispensing cycle than during a main phase of the dispensing cycle.

6. A pump dispenser as claimed in claim 5, in which the outlet valve arrangement is configured so that no air is dispensed during the main phase of each dispensing cycle.

7. A pump dispenser as claimed in claim 5 or claim 6, in which the outlet valve arrangement is configured so that air is only dispensed during the end phase of each dispensing cycle.

8. A pump dispenser as claimed in any one of the previous claims, in which the dispenser is configured such that the air in the air pump chamber is raised to a peak pressure which is less than the peak pressure achieved by the liquid in the liquid pump chamber.

9. A pump dispenser as claimed in claim 8, in which the dispenser is configured such that the liquid in the liquid pump chamber is raised to a peak pressure in the range of 0.3 MPa to IMPa (3 to 10 bar), and more particularly in the range of 0.4 MPa to 0.6Mpa (4 to 6 bar), the air in the air pump chamber being raised to a peak pressure in the range of 0.05 MPa to 0.3 MPa (0.5 to 3 bar).

10. A pump dispenser as claimed in any one of the previous claims in which the dispenser is configured such that air is dispensed from the air pump chamber at a higher pressure during an end phase of the dispensing cycle than during other phases of the dispensing cycle.

11. A pump dispenser as claimed in any one of the previous claims, in which the dispenser is configured such that the total ratio of air to fluid dispensed over each dispensing cycle is in the range of 4:1 to 12:1.

12. A pump dispenser as claimed in anyone of the previous claims, in which the actuator is closed at one end and has an annular wall extending towards the mounting member, the dispenser comprising air chamber seal arrangement operative to define a variable volume air pump chamber at least partly contained within the internal volume of the actuator.

13. A pump dispenser as claimed in claim 12, in which an interior region of the body surrounding the piston above the seal member is in fluid connection with the interior of the actuator to form an extension of the air pump chamber.

14. A pump dispenser as claimed in claim 12, in which the dispenser comprises a seal operative to fluidly isolate an interior region of the body surrounding the piston from the air pump chamber.

15. A pump dispenser as claimed in claim 12, in which the seal arrangement comprises an air chamber seal operative between the turret collar and an inner surface of the annular wall to define the air pump chamber.

16. A pump chamber as claimed in claim 15, in which the dispenser also comprises a seal as claimed in claim 14, such that the whole of the air pump chamber is defined within the interior of the actuator.

17. A pump dispenser as claimed in claim 15 or claim 16, in which the air chamber seal is an integral part of the turret collar.

18. A pump dispenser as claimed in claim 15 or claim 16, in which the air chamber seal is a separate seal member mounted to the turret collar.

19. A pump dispenser as claimed in claim 12, in which the air chamber seal is operative between the annular wall and a surface of the mounting member to define the air chamber.

20. A pump dispenser as claimed in claim 19, in which the mounting member comprises an annular flange that projects towards the actuator, the annular wall of the actuator and the flange overlapping in close relation when the actuator is depressed, the air chamber seal arrangement including a seal operative between the flange and the actuator wall to define the air pump chamber.

21. A pump dispenser as claimed in claim 20, in which the air chamber seal arrangement comprises a resilient seal member integrally formed on an end region of the actuator wall for engagement with the flange.

22. A pump dispenser as claimed in claim 12, in which the air chamber seal arrangement comprises a flexible member connected between the annular wall and one of the turret collar and the mounting member to define the air pump chamber.

23. A pump dispenser as claimed in claim 12, in which the flexible member is one of a bellows and a rolling diaphragm.

24. A pump dispenser as claimed in claim 4, in which the outlet valve arrangement comprises a pre-compression liquid pump chamber outlet valve configured to open to allow liquid to exit the liquid pump chamber only when the pressure of the liquid in the liquid pump chamber is higher than atmospheric by a first predetermined amount.

25. A pump dispenser as claimed in claim 24, in which the outlet valve arrangement comprises a one-way outlet valve for the air-pump chamber.

26. A pump dispenser as claimed in claim, 25, in which the air pump chamber outlet valve is a pre-compression valve configured to open to allow air to exit the air pump chamber only when the pressure of the air in the air pump chamber acting on one side of the valve is higher than the pressure of the fluid acting on the other side of the valve by a second predetermined amount.

27. A pump dispenser as claimed in claim 25, in which the air is mixed with the liquid in a low pressure region of the outlet fluid passageway.

28. A pump dispenser as claimed in claim 27, in which the dispenser is a spray dispenser and the constricted orifice is a spray nozzle forming part of a final outlet of the dispenser, the outlet passageway arrangement being configured to introduce air from the air chamber into the liquid flow path in a swirl chamber immediately upstream of the spray nozzle.

29. A pump dispenser as claimed in claim 27, in which the dispenser is a spray dispenser and the constricted orifice is a spray nozzle forming part of a final outlet of the dispenser, the outlet passageway arrangement including at least one expansion chamber upstream of the spray nozzle, the outlet passageway arrangement being configured to introduce air from the air chamber into the liquid flow path within the expansion chamber.

30. A pump dispenser as claimed in any one of the previous claims, in which the dispenser is a foam dispenser, the outlet including a foam passage and the constricted orifice being configured to produce a spray, jet or sheet of liquid upstream of the foam passage.

31. A pump dispenser as claimed in any one of the previous claims, in which the dispenser is a foam dispenser, the outlet including a foam passage and the constricted orifice being configured to produce a spray or sheet of liquid upstream of the foam passage.

32. A pump dispenser as claimed in claim 30 or claim 31, in which the constricted orifice and at least part of the least part of the foam passage into which the orifice opens is located within the actuator.

33. A pump dispenser as claimed in any one of claims 30 to 32 when dependent on claim 25, in which the outlet passageway arrangement is configured to introduce air from the air chamber into the liquid flow path downstream from the constricted orifice.

34. A pump dispenser as claimed in claim 33, in which the outlet comprises a mixing chamber, the constricted orifice being configured to direct liquid into the mixing chamber in use and the outlet passageway arrangement being configured to direct air from the air chamber into the mixing chamber.

35. A pump dispenser as claimed in any one of claims 30 to 34, in which the foam passage includes a filter arrangement for refining the foam, the filter arrangement comprising at least two regions of open celled foam spaced apart in the direction of flow.

36. A pump dispenser as claimed in claim 35, in which the at least two regions are formed as an integral plug of open celled material received within the foam passage, the plug having at least one slot or cavity extending part way across the plug to form a gap between the spaced regions.

37. A pump dispenser as claimed in any one of the preceding claims, the dispenser comprising an arrangement which permits the actuator to move relative to the mounting member to compress the air pump chamber before an outlet valve of the liquid pump chamber opens in use.

38. A pump dispenser as claimed in claim 37, in which the dispenser comprises a compressible member located in the liquid pump chamber.

39. A pump dispenser as claimed in claim 37, in which the dispenser is configured to draw a volume of air or other gas into the liquid pump chamber.

40. A pump dispenser as claimed in claim 37, in which the actuator is operatively connected with the piston by means of a linkage configured to enable the actuator to move towards the mounting member by a predetermined distance before pressure is applied to the liquid by the piston and seal member.

41. A pump dispenser as claimed in claim 37, in which there is an opening in the body part way along the liquid chamber, the arrangement being such that when the actuator is depressed, the piston and seal member are able to move relative to the body until the seal member closes the opening before liquid in the chamber is pressurised.

42. A pump dispenser as claimed in claim 26, in which the piston has an internal bore forming part of an outlet flow path from the liquid chamber to the dispenser outlet, the air chamber outlet comprising at least one opening in a wall of the piston fluidly connecting the air chamber with the bore and a resiliently deformable valve member mounted in the bore, the valve member contacting an inner surface of the piston to close the opening in an initial resiliently biased configuration and being configured to deform away from the surface to allow air to enter the bore through the opening when the pressure of the air in the air chamber is greater than the pressure inside the bore by the second predetermined amount.

43. A pump dispenser as claimed in claim 42, in which the valve member is a valve sleeve.

44. A pump dispenser as claimed in claim 26, in which the piston has an internal bore forming part of an outlet flow path from the liquid chamber to the dispenser outlet, the air chamber outlet comprising at least one opening in a wall of the piston for fluidly connecting the air chamber with the bore and a valve member slidably engaging an outer surface of the piston, the valve member having one or more openings which are configured to align with the opening in the piston to allow air to enter the bore when the piston is moved relative to the valve member by a predetermined amount during actuation of the dispenser.

45. A pump dispenser as claimed in claim 44, in which the opening in the valve member is configured to align with the opening in the piston only during an end phase of each dispensing cycle.

46. A pump dispenser as claimed in claim 44, in which there are two openings in the valve member, a first of the openings being configured to align with the opening in the piston only during an initial phase of each dispensing cycle and a second of the openings in the valve member being configured to align with the opening in the piston only during an end phase of each dispensing cycle

47. A pump dispenser as claimed in claim 26, in which the piston has an internal bore forming part of an outlet flow path from the liquid chamber to the dispenser outlet, the actuator having an inner portion defining a further bore in which a free end of the piston is received, the further bore also forming part of the outlet flow path for the liquid, the air chamber outlet comprising a flow path from the air chamber into the further bore and a valve member for controlling the flow of air into the further bore from the flow path, the valve member being resiliently deformable from an initial biased configuration in which it closes the flow path to a deformed configuration in which the flow path is opened when the pressure of the air acting on one side of the valve member is greater than the pressure of the fluid acting on the other side of valve member by said second predetermined amount.

48. A pump dispenser as claimed in claim 47, in which the flow path includes a groove between the piston and the inner portion and an opening in the piston at or close to the free end through which air can flow from the groove to enter the further bore when the valve member is open, the valve member comprising a valve sleeve located in the piston bore close to the free end, at a least a portion of the sleeve being resiliently deformable between a resiliency biased position in which it abuts an inner surface of the piston to close the opening and a deformed position in which it is displaced away from the surface to allow air to pass through the opening.

49. A pump dispenser as claimed in claim 47, in which the valve member comprises a resiliently deformable annular valve member mounted between the free end of the piston and a surface of the inner portion, the valve member being deformable from an initial resiliently biased configuration in which it prevents air flowing between the free end of the piston and the surface of the inner portion to enter the further bore and a deformed condition in which air is able to flow past it to enter the further bore.

50. A pump dispenser as claimed in claim 49, in which the valve member is an O- ring.

51. A pump dispenser as claimed in any one of claims 30 to 36, in which the spray nozzle is a fan jet nozzle adapted to produce a sheet of liquid.

52. A pump dispenser as claimed in any one of claims 30 to 36, in which the spray nozzle is a conical jet nozzle adapted to produce a conical sheet of liquid.

53. A pump dispenser as claimed in any one of the previous claims, in which a pre-compression outlet valve for controlling the flow of liquid from the liquid chamber to the outlet is located adjacent the constricted orifice, the pre- compression outlet valve being configured to open to allow liquid to flow to the orifice only when liquid at the valve is at or above the first threshold pressure.

54. A pump dispenser as claimed in any one of the preceding claims, in which the dispenser is configured such that in use during each dispensing cycle, air begins to flow through the outlet passageway arrangement before liquid is released from the liquid pump chamber.

55. A pump dispenser as claimed in any one of the preceding claims, in which the dispenser is configured such that in use during the dispensing cycle, air continues to flow through the outlet passageway arrangement for a limited amount of time after all the liquid has been dispelled from the outlet passageway.

56. A method of manufacturing a pump dispenser as claimed in any one of the previous claims, the method comprising: a. modifying the design of a pre-existing cylindrical liquid only pump dispenser to incorporate the air pump arrangement; b. manufacturing the pump dispenser using at least some of the original tooling used to produce the pre-existing cylindrical liquid pump dispenser.

57. A method as claimed in claim 56, the method comprising modifying some of the original tooling and using the modified tooling to produce modified components for the pump dispenser.