WO2025018884A1

WO2025018884A1 - Device and system for dispensing a liquid

Info

Publication number: WO2025018884A1
Application number: PCT/NL2024/050389
Authority: WO
Inventors: Paulo Nervo; Petrus Lambertus Wilhelmus Hurkmans; Lukas Jacob Willem VAN DEN HEUVEL
Original assignee: Dispensing Technologies B.V.
Priority date: 2023-07-15
Filing date: 2024-07-15
Publication date: 2025-01-23

Abstract

The invention relates to a device for dispensing a liquid from a container, comprising an inlet channel configured to be brought in fluid communication with the container, a pump in fluid communication with the inlet channel, the pump including a pump chamber and a piston reciprocally movable in the pump chamber, and an inlet valve arranged between the inlet channel and the pump. The liquid dispensing device further comprises a buffer in fluid communication with the pump, a nozzle for dispensing the liquid, the nozzle in fluid communication with the pump and/or the buffer, and an outlet valve arranged between the pump and/or buffer and the nozzle. The buffer comprises an elastic buffer bag arranged at least partially in the piston. The elastic buffer bag defines an internal volume and has an opening in fluid communication with the pump.

Description

DEVICE AND SYSTEM FOR DISPENSING A LIQUID

The invention relates to a device for dispensing a liquid from a container as a spray or as a foam. In particular, the invention relates to a liquid dispensing device which allows a liquid to be dispensed at a precisely controlled output pressure, and thus allows droplet sizes to be maintained within a narrowly defined range.

More specifically, the invention relates to a liquid dispensing device comprising an inlet channel configured to be brought in fluid communication with the container; a pump in fluid communication with the inlet channel, the pump including a pump chamber and a piston reciprocally movable in the pump chamber; an inlet valve arranged between the inlet channel and the pump; a buffer in fluid communication with the pump; a nozzle for dispensing the liquid, the nozzle in fluid communication with the pump and/or the buffer; and an outlet valve arranged between the pump and/or buffer and the nozzle. Such a liquid dispensing device is known, e.g. from WO 2013/043938 Al.

This prior art document by the present applicant discloses a liquid dispensing device having a buffer arranged opposite the pump, which extends downwardly from the device into the neck of a container. This buffer includes a buffer chamber in which a spring-loaded buffer piston is arranged. When liquid is moved from the pump into the buffer, the piston is forced downward, thus loading the spring. Once pumping has stopped, the spring relaxes, thus forcing liquid from the buffer towards the nozzle. This prior art buffer design takes up a relatively large amount of space and includes an assembly of individual parts which complicates manufacture of the liquid dispensing device.

US 11 498 089 B2 discloses a manually operated trigger sprayer that stores a quantity of pressurized liquid during the charge stroke of the trigger for subsequent release during the return stroke. The trigger sprayer is configured such that an appreciable volume of liquid is dispensed during both the charge and the return strokes of the trigger, creating a continuous discharge stream, for so long as the trigger is actuated. The pressurized liquid is stored in an elastic tube that is attached to a nipple extending rearwardly from the back of the housing of the trigger sprayer.

US 11 519 394 B2 discloses a pump including an inlet one-way valve; a pump chamber downstream of and in fluid communication with the inlet one-way valve; a piston slideably engaged with the pump chamber; a piston cavity within the piston and in fluid communication with the pump chamber; a liquid accumulator operable within the piston cavity; an actuator engaged with piston; and an outlet one-way valve downstream of and in fluid communication with the pump chamber. The liquid accumulator may be a gas-filled bladder accumulator, a diaphragm accumulator, a gas filled piston accumulator, a spring loaded piston accumulator or a compressible medium accumulator. US 2022/401984 Al discloses a trigger sprayer which includes an engine with a piston chamber and an outlet fluid passage, and a piston that slides within the piston chamber and defines an interior bellows chamber. A bellows component is movable in the interior bellows chamber between an uncompressed position in which a fluid volume in the interior bellows chamber is minimized and a compressed position in which the fluid volume is maximized. The trigger sprayer further includes a trigger lever that pivots between a neutral position and an actuated position using a pair of S-shaped trigger springs. Pivotal movement of the trigger lever pushes the piston vertically in the piston chamber to drive fluid from the piston chamber into the interior bellows chamber and move the bellows component from the uncompressed position to the compressed position. Relaxation of the bellows component drives fluid from the interior bellows chamber to the outlet fluid passage.

The invention has for its object to provide a liquid dispensing device of the type discussed above which is structurally simple, which is relatively easy to assemble, and which may be manufactured at relatively low cost.

In accordance with the invention, this is achieved in a liquid dispensing device of the type described above, wherein the buffer comprises an elastic buffer bag arranged at least partially in the piston, the elastic buffer bag defining an internal volume and having an opening in fluid communication with the pump. An elastic buffer bag does not require moving parts and a separate spring, and as such is easier to manufacture than prior art buffers. Moreover, it allows the entire dispensing device to be made of plastics material, which facilitates recycling at the end of the life cycle. By arranging the buffer bag in the piston, efficient use is made of the available space, thus resulting in a compact design.

In an embodiment, the opening of the elastic buffer bag may be arranged in a side of the piston bordering the pump chamber. In this way liquid may flow directly from the pump chamber into the buffer bag during pumping.

In a further embodiment, the opening of the elastic buffer bag may be enclosed by a neck which is sealingly connected to an inner peripheral edge of the piston. In this way, no liquid can escape past the buffer bag. The neck may have an enlarged diameter, and may engage a reduced diameter part of the piston in order to fix the buffer bag in the piston.

In another embodiment, the elastic buffer bag and the piston may be integrally made. This reduces the number of assembling steps, as well as the number of separate parts to be manufactured and stocked.

In an embodiment, the liquid dispensing device may further comprise a core element arranged in the elastic buffer bag. Such a core element prevents the buffer bag from collapsing when it is emptied, which would complicate refilling the buffer bag in a next pump stroke. In such an embodiment, the core element substantially may fill the internal volume of the elastic buffer bag. In this way the amount of “dead” volume in the device at the end of a pump stroke may be reduced, thus facilitating priming of the device. By varying the size of the core element in relation to the internal volume of the elastic buffer bag when relaxed, an amount of stretching of the buffer bag when introducing the core element may be adjusted. Stretching occurs when the size of the core element is larger than the internal volume of the elastic buffer bag in its state of relaxation. The amount of stretching in turn defines a minimum pressure at which the liquid enters the buffer bag.

On the other hand, the core element may leave free a substantial part of the internal volume, thus increasing the storage capacity of the buffer bag. Thus, the core element may take up e.g. 10%, 25%, 50%, 75% or approximately 100% of the internal volume of the elastic buffer bag in its state of relaxation.

In an embodiment, the core element may have an end face bordering the pump chamber. In this way the relatively stiffer core element forms part of the piston surface contacting the liquid in the pump chamber.

In a further embodiment, the core element may include at least one recess in fluid communication with the pump chamber. This recess may be filled with liquid, so as to maintain a minimal space between the core element and the buffer bag which will allow liquid to enter.

In order to allow liquid to fill the entire interior volume of the buffer bag, the at least one recess may be a groove extending over substantially an entire length of the core element. Alternatively, a channel could be arranged within the core element which could fluidically connect to another channel leading to the exterior surface of the core element. The core element might also have a cross section which is oval shaped, triangular shaped, cross shaped or any other shape which would leave a recess between the outside of the core element and the inside wall of the buffer bag.

In an embodiment, the piston may define an internal volume that is larger than an external volume of the elastic buffer bag when empty. In this way there is room within the piston for the buffer bag to expand when it is filled with liquid from the pump.

The necessary room may be provided around the buffer bag if the piston has an internal diameter that is larger than an external diameter of a cylindrical part of the elastic buffer bag. This allows for radial expansion of the buffer bag. The piston may be substantially cylindrical, but other cross-sectional shapes may be envisioned as well.

In a further embodiment, the piston may be tubular and may have openings on opposite sides. In this case the opening on the side facing the pump chamber accommodates the open side of the buffer bag, while the opening on the opposite side allows the buffer bag to expand in lengthwise direction. In an embodiment, the elastic buffer bag may be made of a thermoplastic elastomer (TPE) or a natural or synthetic rubber, in particular a silicone rubber. Thermoplastic elastomers have the ability to be stretched to moderate elongations and, upon the removal of stress, return to something close to their original shape. Moreover, they are processable as a melt at elevated temperature, and are free from significant creep. The thermoplastic elastomer for the buffer bag may be selected from styrene block copolymers (TPS or TPE-S), thermoplastic polyolefin elastomers (TPO or TPE-O), thermoplastic vulcanizates (TPV or TPE-V), thermoplastic polyurethanes (TPU or TPE- U), thermoplastic copolyesters (TPC or TPE-E), thermoplastic polyamides (TPA or TPE- A), and unclassified thermoplastic elastomers (TPZ).

In an embodiment, the elastic buffer bag may be made of a recyclable material, in particular a styrene block copolymer (TPS or TPE-S). This allows the entire dispensing device to be recycled as a whole, without having to disassemble the various parts.

In a further embodiment, the styrene block copolymer may comprise Thermolast® K from Kraiburg TPE (www.kraiburg-tpe.co ), which is a low-cost and durable material that is easy to process and easy to recycle.

In case the elastic buffer bag and the piston are integrally made, the piston may be made of a polyolefin, such as PP or PE, in particular HDPE, and the elastic buffer bag and the piston may be made by 2C injection molding.

In an embodiment of the liquid dispensing device, the internal volume of the elastic buffer bag may be in open communication with the pump chamber. In this way dispensing of the liquid will be interrupted as soon as the pump is no longer actuated, since the liquid stored in the buffer bag will simply flow back into the pump chamber. This concept is identified as “direct stop”.

In a further embodiment, a difference in volume between a fully expanded state and a relaxed state of the elastic buffer bag may be at least 30 % of a displacement volume of the pump, in particular at least 40 %, more in particular at least 50 %, even more in particular at least 60 %, most in particular at least 70%, preferably at least 80 %, more preferably at least 90 % of the displacement volume, and most preferably substantially equal to the displacement volume. In this case the amount of buffer capacity that is needed, i.e. the difference in volume between the elastic buffer bag in relaxation and the buffer bag when fully expanded, is determined by the swept volume or displacement volume of the pump. The displacement volume is defined as the volume that is displaced during a full stroke of the piston, i.e. the cross-sectional area of the piston chamber multiplied by the distance which the piston can travel.

Since the buffer is in open communication with the pump chamber, the maximum amount of liquid that has to be stored in the buffer equals the volume that is displaced during a single pump stroke. The volume of the elastic buffer bag in its fully expanded state is limited only by the inner sidewall of the piston. The dimensions of the elastic buffer bag are selected such that when it is expanded to the point where it is radially restricted by the piston, its fully expanded state in the sense of the present disclosure, the material of the bag is still (well) within its elastic range. In this way, the liquid may be buffered at a relatively lower pressure.

It is also conceivable that the bag is dimensioned such that its internal volume, when restricted by the piston sidewall, is greater than the displacement volume of the pump. In that case the bag would never reach its fully expanded state, and the liquid pressure in the buffer bag would be even lower. The internal volume of the bag when expanded to come into contact with the piston sidewall could be two times or even four times the displacement volume of the pump. For instance, the internal volume of the bag when expanded to come into contact with the piston sidewall could be 1 or 2 ccm, while the displacement volume of the pump could be 0.5 ccm. Such dimensions would lead to a very gradual pressure build-up.

In a further embodiment the outlet valve may be a pre -compression valve. Such a precompression valve opens and closes at a well-defined and somewhat elevated pressure, thus providing a clear cut-off when dispensing liquid, and preventing any dripping of liquid.

In another embodiment, the pump chamber may have an axis defining a direction of reciprocal movement of the piston which is arranged at an angle with respect to an axis of the inlet channel. In this way a compact pump design is achieved, in which the amount of channels which potentially form “dead” spaces is minimized. Such a design allows the pump to be primed relatively easily. In particular, the axis defining the direction of reciprocal movement of the piston may be substantially perpendicular to the axis of the inlet channel.

The invention further provides a system for dispensing a liquid, which comprises a container and a liquid dispensing device of the type described above connected to the container.

The invention will now be illustrated by way of a number of exemplary embodiments, with reference being made to the annexed drawings, in which like elements are identified by reference numerals increased by 100, and in which:

Fig. 1 is a side view of a system for dispensing a liquid which comprises a container and a first embodiment of a liquid dispensing device connected thereto;

Fig. 2 is a front view of the system of Fig. 1 ;

Fig. 3 is an enlarged scale cross-sectional view along the lines III-III in Fig. 2, showing the liquid dispensing device at rest, when the buffer bag is empty;

Fig. 4 is a view corresponding with Fig. 3, showing the device during dispensing, when the buffer bag is filled;

Fig. 5 is a view corresponding with Figs. 3 and 4, showing the device at the end of dispensing, when the buffer bag has been emptied;

Fig. 6 is a perspective view showing a piston and buffer of the liquid dispensing device of Figs. 3-5; Fig. 7 is a cross-sectional view along the lines VII- VII in Fig. 6;

Fig. 8 is a cross-sectional view corresponding with Fig. 3 of a second embodiment of the liquid dispensing device at rest, when the buffer bag is empty;

Fig. 9 is a cross-sectional view of main components of a third embodiment of the liquid dispensing device at rest with an empty buffer bag;

Fig. 10 is a view corresponding to Figs. 3 and 8, showing a fourth embodiment of the dispensing device of the invention in its position of rest; and

Fig. 11 is a view corresponding to Fig. 10, showing the dispensing device with the piston at the end of its stroke and the buffer bag completely filled.

A system 1 for dispensing a liquid comprises a container 2 which is at least partially filled with the liquid to be dispensed and which has a neck (not shown). The system 1 further comprises a liquid dispensing device 3 connected to the neck of the container 2 by an annular connector 4 (Figs. 1, 2).

The liquid dispensing device 3 comprises a pump 5 which includes a pump chamber 6 and a piston 7 that is reciprocally movable in the pump chamber 6 as indicated by arrow R (Figs. 3-5). The device 3 further comprises a movable actuator 8, in the illustrated embodiment a trigger, which is operatively coupled to the piston 7. The actuator 8 may be pivotable or slidable as indicated by arrow T. It may be moved inward (to the right in the drawing) by a user exerting force to initiate a pump stroke, and may be moved outward by e.g. a return spring (not shown).

The liquid dispensing device 3 further comprises an inlet channel 14 which is configured to be brought in fluid communication with the container 2. In the illustrated embodiment the inlet channel 14 accommodates a top end of a dip tube 15 which extends into the container 2. The inlet channel 14 leads to an inlet opening 16 of the pump 5, which may be closed by an inlet valve 17 sealingly abutting a valve seat 33.

The liquid dispensing device 3 also comprises a buffer 9 which is in fluid communication with the pump 5, as will be described in more detail below.

The liquid dispensing device 3 further comprises a nozzle 12 having a dispensing orifice 25 for dispensing the liquid. In the illustrated embodiment the nozzle 12 is in fluid communication with the pump 5 and with the buffer 9 as well. The fluid communication between the nozzle 12 and the buffer 9 runs through the pump chamber 6, while the fluid communication between the pump chamber 6 and the nozzle 12 is established through an outlet channel 24. The outlet channel 24 is in communication with the pump chamber 6 through a pump outlet opening 19, a valve chamber 20 and an outlet opening 22.

An outlet valve 13 is arranged between the pump 5 and buffer 9 on the one hand and the nozzle 12 on the other. In the illustrated embodiment the outlet valve 13, is a pre -compression valve, more in particular a dome valve which is arranged in the valve chamber 20 that communicates with the pump chamber 6 through the pump outlet opening 19. The dome valve 13 is locked in the valve chamber 20 by an end wall 21. The dome valve 13 comprises a substantially cylindrical sleeve 26 extending from the end wall 21 towards the pump outlet opening 19 and carrying the actual dome 27. This dome 27 sealingly abuts a valve seat 23 surrounding the outlet opening 22 to interrupt the fluid communication between the pump 5 and elastic buffer 9 and the nozzle 12. An end part of the sleeve 26 carrying the dome 27 is sealingly received in an annular flange 28.

In the illustrated embodiment, the valve chamber 20 is shown to be offset from but parallel to the pump chamber 6. The inlet valve 17 is shown to be formed by a peripheral lip of the sleeve 26, which is flexible and may be urged away from a peripheral wall of the valve chamber 20 which forms the valve seat 33 into a recess in the annular flange 28 to allow fluid flow through the inlet opening 16, as shown in dotted lines in Fig. 3.

In this embodiment, the connector 4 connecting the liquid dispensing device 3 to the container 2 comprises a ring having inner threading 29 which cooperates with outer threading on the container neck (not shown).

In the illustrated embodiment, the various parts of the liquid dispensing device 3 are covered by a shroud 31 extending between the annular connector 4 and the nozzle 12.

The pump chamber 6 is shown to have an axis P defining the direction R of the reciprocal movement of the piston 7 which is substantially perpendicular to an axis I of the inlet channel 14. In other words, during normal use of the liquid dispensing system 1, when the container 2 and the inlet channel 14 will be substantially vertically oriented, the pump chamber 6 will be substantially horizontal. This arrangement allows for a compact construction having a relatively limited amount of “dead” volume.

In accordance with the invention, the buffer 9 comprises an elastic buffer bag 10 which is arranged in the piston 7. The elastic buffer bag 10, which defines an internal volume Vb, has an opening 11 which is in fluid communication with the pump 5. In the illustrated embodiment the elastic buffer bag 10 has a cylindrical part 18 extending from the opening 11 towards a closed end part 32. In the illustrated embodiment the opening 11 of the elastic buffer bag 10 is arranged in a side 35 of the piston 7 which borders the pump chamber 6. The opening 11 is enclosed by a neck 36 which is sealingly connected to an inner peripheral edge 37 of the piston 7.

In this embodiment the neck 36 has an enlarged diameter and engages a part of the piston 7 having a reduced diameter in the form of an inwardly extending flange 38. This engagement ensures that the elastic buffer bag 10 is fixed in the piston 7 and may withstand the pressures that are generated during pumping. As shown in Figs. 3 and 5, the piston 7 has an internal volume Vp that is larger than an external volume of the elastic buffer bag 10 when this is empty. The piston 7 is shown to be cylindrical and its internal diameter Di is shown to be larger than an external diameter do of the cylindrical part 18 of the buffer bag 10, thus creating an annular space 39 around the buffer bag 10 in its empty state.

The elastic buffer bag 10 can be made of a thermoplastic elastomer (TPE) or a natural or synthetic rubber, in particular a silicone rubber. In order to allow the liquid dispensing device 3 to be recycled, the elastic buffer bag 10 can be made of a recyclable material, in particular a styrene block copolymer (TPS or TPE-S). A suitable material for the elastic buffer bag 10 is Thermolast® K from Kraiburg

In the illustrated embodiment a core element 40 is arranged in the buffer bag 10. This core element 40 substantially fills the internal volume Vb of the buffer bag 10 when this is empty, thus minimizing the amount of “dead” volume in the dispensing device 3 at the end of a pump stroke, which makes it easier to prime the device, i.e. remove any air before first use. The core element 40, which is made from a relatively stiff material, e.g. a plastic like polypropylene or polyethylene, is shown to have a substantially T-shaped cross-section to conform to the widened neck 36 and narrower cylindrical segment 18 of the buffer bag 10.

The core element 40 has an end face 41 which extends over the entire internal diameter Di of the piston 7 and which has a peripheral edge received in a peripheral groove in the piston 7. The end face 41 of the core element 40 borders the pump chamber 6, thus forming the surface of the piston 7 which acts on liquid in the pump chamber 6 during dispensing. The piston 7 itself is formed as a tube which is open at both ends (Figs. 6, 7), the open end 42 of the piston 7 opposite the end face 41 allowing for longitudinal expansion of the elastic buffer bag 10. In order to allow liquid to enter the buffer bag 10, the core element 40 is shown to include a recess 45, in this case a groove in an outer surface 34 which extends all the way to its end 30. This groove 45 is in fluid communication with the pump chamber 6 through a bore 43 in the end face 41 of the core element 40.

As can be seen from Figs. 3 and 4, when the dispensing device 3 is in its position of rest, the elastic buffer bag 10 is arranged around the core element 40 and the internal volume Vb of the buffer bag 10 corresponds substantially with the external volume of the core element 40. On the other hand, when the dispensing device 3 is operated and liquid is stored in the elastic buffer bag 10, its internal volume will increase until it substantially corresponds with the internal volume Vp of the piston 7 - minus the volume taken up by the elastic material of the wall of the buffer bag 10. The difference in volume between the expanded state of the elastic buffer bag 10 shown in Fig. 4 and the relaxed state shown in Fig. 3 may be at least 30 % of a displacement volume of the pump, in particular at least 40 %, more in particular at least 50 %, even more in particular at least 60 %, most in particular at least 70%, preferably at least 80 %, more preferably at least 90 % of the displacement volume, and may even be substantially equal to the displacement volume. Apart from accommodating the elastic buffer bag 10, the piston 7 is conventional and includes two annular seals 44, 46 for sealing the pump chamber 6 and for sealing a vent opening 47 which can be brought into fluid communication with the interior of the container 2. The piston further includes two mounting openings 48 for receiving mounting pins (not shown) of the actuator or trigger 8.

During use of the liquid dispensing system 1 , the pump 5 will first be primed by operating the trigger 8 one or more times. Because the “dead” volume at the end of a stroke that can be filled with air is relatively small, priming does not require many pump strokes. After priming, whenever the piston 7 is moved outward by the return spring after a pump stroke, to the position shown in Fig. 3, liquid will be drawn from the container 2 through the dip tube 15, the inlet channel 14, and the inlet opening 16 into the pump chamber 6. During such a return stroke or suction stroke, the inlet valve 17 will be lifted from its valve seat 33 as a result of the suction applied by the piston 7 moving outward, thus allowing the liquid to flow through the inlet opening 16.

During a subsequent pump stroke, as the piston 7 is moved inward by the trigger 8, the inlet valve 17 will be closed by the pressure created by the piston 7 moving inward, and the liquid in the pump chamber 6 will be forced through the pump outlet opening 19 into the valve chamber 20. There the liquid pressure will act on the dome-shaped part 27 of the pre-compression outlet valve 13. When the pressure of the liquid in the pump chamber 6 exceeds a cracking pressure of the pre-compression valve 13, the pre-compression valve 13 will be moved from its valve seat 23 by deformation of the dome 27 (Fig. 4), allowing the liquid to flow through the outlet opening 22 and the outlet channel 24 towards the nozzle 12 to be dispensed through the orifice 25.

The dimensions of the various parts of the liquid dispensing device 3 are such that the orifice 25 cannot dispense the liquid at the same rate as it is pressurized and forced past the precompression valve 13 by actuation of the pump 5. Pressurized liquid that cannot be dispensed through the orifice 25 flows through the bore 43 in the end face 41 into the groove 45 of the core element 40. The liquid in the groove 45 then forces the cylindrical part 18 of the elastic buffer bag 10 outwards, away from the outer surface 34 of the core element 40, thus creating more room for accommodating liquid (Fig. 4). This expansion of the elastic buffer bag 10 is controlled by the piston 7, which limits the extent to which the buffer bag 10 can be stretched.

If the piston 7, after having reached the inner end of its stroke, is held in that position by a user continuing to exert force on the trigger 8, the pressurized liquid that has accumulated in the buffer bag 10 is forced out by contraction of the elastic buffer bag 10, which returns to its initial shape (Fig. 5). As long as the pressure stored in the elastic buffer bag 10 exceeds the cracking pressure of the pre-compression valve 13, this liquid will be forced past the pre-compression valve 13 towards the nozzle 12, to be dispensed through the orifice 25. In this way liquid is dispensed from the nozzle 12 for a prolonged period. When the user stops actuating the pump 5, the trigger 8 will be returned to its initial position by the return spring, thus also causing the piston 7 to be returned. This will cause the liquid flow to be interrupted immediately, regardless of the amount of liquid that may still remain in the buffer. This is because the remaining liquid in the device 3 will be distributed over the volume of the pump chamber 6 and the internal volume Vb of the elastic buffer bag 10, so that its pressure will fall below the cracking pressure of the pre-compression valve 13 (Fig. 3). The abrupt closure of the pre-compression valve 13 will prevent any dripping.

In an alternative embodiment of the liquid dispensing device 103, the pump chamber 106 has an axis P which is parallel to the axis I of the inlet channel 114. An inlet channel 149 runs from the inlet opening 116 to the pump chamber 106. In this embodiment the inlet valve 117 is shown to comprise a disk that is movable with respect to an annular valve seat 133 surrounding the inlet opening 116.

The buffer 109 is again arranged in the piston 107, and comprises an elastic buffer bag 110 and a core element 140. The piston 107 is connected to the actuator 108 by a mechanism (not shown) which transforms the pivoting or sliding movement of the actuator 108 in the direction of arrow T into vertical reciprocating movement of the piston 107 as indicated by arrow R.

In this embodiment, the pump outlet opening 119 leads to a bend 150 directing liquid into a vertical intermediate channel 151, which in turn leads to the valve chamber 120. In the valve chamber 120, the dome valve 113 once again sealingly abuts the valve seat 123 surrounding the outlet channel 124. The outlet channel 124 guides the liquid to the orifice 125 of the nozzle 112.

Further structural features, as well as the operation of this embodiment of the liquid dispensing device 103 are the same as those of the first embodiment, discussed in connection with Figs. 3-5.

Instead of being perpendicular or parallel to the axis I of the inlet channel 214, in a further embodiment of the liquid dispensing device 203 the pump chamber 206 has an axis P which is arranged at an acute or obtuse angle a with respect to the axis I of the inlet channel 214 (Fig. 9). Here again, the buffer 209 is arranged in the piston 207, and comprises an elastic buffer bag 210 and a core element 240.

Like in the second embodiment, the inlet valve 217 here comprises a disk that is movable with respect to the annular valve seat 233 surrounding the inlet opening 216. In this embodiment, a vent channel 152 connects the vent opening 247 with the interior of the annular connector 204. A short intermediate channel 251 forms the fluid communication between the pump outlet opening 219 and the outlet valve 213. In this embodiment the outlet valve 213 has a similar structure as the inlet valve 217. The outlet valve 213 comprises a disk that is movable with respect to an annular valve seat 223, which here surroundings the end of the intermediate channel 251. The outlet channel 224, which connects the outlet valve 213 with the nozzle orifice 225, is here shown to have a vertical and a horizontal segment connected by a bend 250.

Although not shown here, this third embodiment may also include a shroud covering the various components of the liquid dispensing device 203.

Further structural features, as well as the operation of this embodiment of the liquid dispensing device 203 are the same as those of the first and second embodiments, discussed in connection with Figs. 3-5 and 8.

Although the buffer bag and piston have been shown and described above as separate parts that can be assembled, it is also conceivable that elastic buffer bag 310 and piston 307 will be integrally made, as shown in the embodiment of Figs. 10 and 11. The elastic buffer bag 310 and the piston 307 may for example be made by a process of injection molding. Integrally forming these two parts reduces the number of assembling steps, as well as the number of separate parts to be made and stocked.

Since the requirements for elastic buffer bag 310 are different from those for piston 307, e.g. when it comes to structural strength and stiffness or flexibility, the elastic buffer bag 310 and the piston 307 may be made from different materials. For instance, piston 307 may be made of a polyolefin, such as PP or PE, in particular HDPE, while elastic buffer bag 310 may be made of a thermoplastic elastomer (TPE) or a synthetic rubber, in particular a silicone rubber. These different materials may be integrated with each other in a bi-injection molding process or 2C injection molding process. In such a process one of the two parts may be injection molded first, and then the second material may be injected into the same mold so as to bond with the first material while still at least partially in a molten state.

A transition 361 between the material forming piston 307 and the material forming elastic buffer bag 310 may be arranged at substantially the same location where the enlarged diameter part of the neck engages the reduced diameter part of the piston in the other embodiments discussed above. In this way the transition area 361 of the integrally molded buffer bag and piston surrounds opening 311 of the elastic buffer bag 310.

In the illustrated embodiment, transition area 361 is clamped between a peripheral ridge 358 protruding from the end face 341 of core element 340 and a base part of core element 340. Since piston 307 is integrally formed with the elastic buffer bag 310, transition area 361 now effectively forms a closed end 335 of piston 307. On the other hand, the opposite end 342 of piston 307, which is connected to trigger 308, is still open in this embodiment, thus providing additional room for expansion of the buffer bag 310. In comparison with the other embodiments, the bore 343 leading to the groove 345 has been widened to facilitate entry of liquid into the groove 345.

It should be noted that the ridge 358 surrounding the transition area 361 is only an exemplary way of connecting the core element 340 with the integrated piston 307 and buffer bag 310. Alternatively, this connection might also be formed by a peripheral edge of the end face 341 being received in a peripheral groove near an inward facing end of the piston 307, like in the previous embodiments. This would require a part of the piston wall to extend past the transition area 361. In this way the buffer bags 10, 110 and 210 of the previous embodiments could also be integrally made with the respective pistons 7, 107, 207 in which they are arranged. Conversely, the illustrated arrangement with the protruding ridge could also be used for clamping together the individual buffer bags 10, 110, 210 and pistons 7, 107, 207 of the previous embodiments.

Further structural features, as well as the operation of this embodiment of the liquid dispensing device 303 are the same as those of the other embodiments, discussed in connection with Figs. 3-5, 8 and 9.

The invention as disclosed herein provides a relatively simple yet effective liquid dispensing device which allows the pressure at which liquid is dispensed, and therefore the bandwidth of the liquid droplets, to be optimally controlled. Optimum control of the dispensing pressure may involve selecting the volume of the elastic buffer bag in both relaxed and expanded state, the material of the buffer bag, the size of a potential core element, the cracking pressure of the outlet valve, in particular the pre-compression valve and the throughput of the nozzle orifice. Due to the presence of a buffer, dispensing may be prolonged when the piston is held at the end of a pump stroke. Since all parts of the dispensing device, including the buffer, are made of plastic materials, the device may be recycled after use, thus reducing the carbon footprint and the amount of waste material.

Although the invention has been described by reference to various exemplary embodiments, it is not limited thereto, and may be varied within the scope of the appended claims.

Claims

1. Device for dispensing a liquid from a container, comprising:

- an inlet channel configured to be brought in fluid communication with the container;

- a pump in fluid communication with the inlet channel, the pump including a pump chamber and a piston reciprocally movable in the pump chamber;

- an inlet valve arranged between the inlet channel and the pump;

- a buffer in fluid communication with the pump;

- a nozzle for dispensing the liquid, the nozzle in fluid communication with the pump and/or the buffer; and

- an outlet valve arranged between the pump and/or buffer and the nozzle; wherein the buffer comprises an elastic buffer bag arranged at least partially in the piston, the elastic buffer bag defining an internal volume and having an opening in fluid communication with the pump.

2. Liquid dispensing device as claimed in claim 1 , wherein the opening of the elastic buffer bag is arranged in a side of the piston bordering the pump chamber.

3. Liquid dispensing device as claimed in claim 2, wherein the opening of the elastic buffer bag is enclosed by a neck which is sealingly connected to an inner peripheral edge of the piston.

4. Liquid dispensing device as claimed in claim 1 or 2, wherein the elastic buffer bag and the piston are integrally made.

5. Liquid dispensing device as claimed in any one of the preceding claims, further comprising a core element arranged in the elastic buffer bag.

6. Liquid dispensing device as claimed in claim 5, wherein the core element substantially fills the internal volume of the elastic buffer bag.

7. Liquid dispensing device as claimed in claim 5 or 6, wherein the core element has an end face bordering the pump chamber.

8. Liquid dispensing device as claimed in claim 6 or 7, wherein the core element includes at least one recess in fluid communication with the pump chamber.

9. Liquid dispensing device as claimed in claim 8, wherein the at least one recess is a groove extending over substantially an entire length of the core element.

10. Liquid dispensing device as claimed in any one of the preceding claims, wherein the piston defines an internal volume that is larger than an external volume of the elastic buffer bag when empty.

11. Liquid dispensing device as claimed in claim 10, wherein the piston has an internal diameter that is larger than an external diameter of a cylindrical part of the elastic buffer bag.

12. Liquid dispensing device as claimed in any one of the preceding claims, wherein the piston is tubular and has openings on opposite sides.

13. Liquid dispensing device as claimed in any one of the preceding claims, wherein the elastic buffer bag is made of a thermoplastic elastomer (TPE) or a natural or synthetic rubber, in particular a silicone rubber.

14. Liquid dispensing device as claimed in claim 13, wherein the elastic buffer bag is made of a recyclable material, in particular a styrene block copolymer (TPS or TPE-S).

15. Liquid dispensing device as claimed in claim 13 or 14 when dependent on claim 4, wherein the piston is made of a polyolefin, such as PE or PP, and wherein the elastic buffer bag and the piston are made by 2C injection molding.

16. Liquid dispensing device as claimed in any one of the preceding claims, wherein the internal volume of the elastic buffer bag is in open communication with the pump chamber.

17. Liquid dispensing device as claimed in any one of the preceding claims, wherein a difference in volume between a fully expanded state and a relaxed state of the elastic buffer bag is at least 30 % of a displacement volume of the pump, in particular at least 40 %, more in particular at least 50 %, even more in particular at least 60 %, most in particular at least 70%, preferably at least 80 %, more preferably at least 90 % of the displacement volume, and most preferably substantially equal to the displacement volume.

18. Liquid dispensing device as claimed in any one of the preceding claims, wherein the outlet valve is a pre-compression valve.

19. Liquid dispensing device as claimed in any one of the preceding claims, wherein the pump chamber has an axis defining a direction of reciprocal movement of the piston which is arranged at an angle with respect to an axis of the inlet channel.

20. System for dispensing a liquid, comprising a container and a liquid dispensing device as claimed in any one of the preceding claims connected thereto.