Liquid dispensing device having an elastic buffer bag and method of manufacturing such elastic buffer bag

Abstract

The invention relates to a device for dispensing a liquid from a container which comprises 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, the buffer comprising an elastic buffer bag defining an expansible volume, 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 elastic buffer bag comprises at least two layers, the at least two layers including a first layer comprising a material having good resistance to the liquid to be dispensed and a second layer comprising a material having a predetermined amount of elasticity. The invention further relates to a method of manufacturing an elastic buffer bag for use in a liquid dispensing device which comprises the steps of forming a first layer comprising a material having good resistance to a liquid to be dispensed, forming a second layer comprising a material having a predetermined amount of elasticity, and mutually connecting the first and second layers.

Description

[0001] LIQUID DISPENSING DEVICE HAVING AN ELASTIC BUFFER BAG AND METHOD OF MANUFACTURING SUCH ELASTIC BUFFER BAG

[0002] The invention relates to a device for dispensing a liquid from a container, which liquid dispensing device comprises an elastic buffer bag. In particular, 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, the buffer comprising an elastic buffer bag defining an expansible volume, 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 disclosed in the applicant’s earlier patent applications PCT / NL2024 / 050389, PCT / EP2024 / 084379 and PCT / NL2024 / 050702.

[0003] The earlier applications each characterize the elastic buffer bag as being made of a thermoplastic elastomer (TPE) or a natural or synthetic rubber. This choice of material is a compromise between various requirements which the elastic buffer bag must meet, and which may sometimes conflict. These requirements include i.a. elasticity, resistance to fluids to be received in the buffer, compatibility with other materials used in the liquid dispensing device, recyclability and low cost.

[0004] The invention has for its object to provide a liquid dispensing device of the type discussed above which is structurally simple, durable, relatively easy to assemble, and which may be manufactured at relatively low cost.

[0005] In accordance with the invention, this is achieved in a liquid dispensing device of the type discussed above, wherein the elastic buffer bag comprises at least two layers, the at least two layers including a first layer comprising a material having good resistance to the liquid to be dispensed and a second layer comprising a material having a predetermined amount of elasticity. By using two or more layers to form the elastic buffer bag, various advantageous characteristics of different materials may be functionally combined.

[0006] In particular, this allows the layer which provides the elasticity to be shielded from direct contact with the liquid by the resistant layer, so that the material for this layer may be selected primarily on the basis of the desired amount of elasticity. This material should have good elastic characteristics and a large degree of material memory allowing it to resume its original size and shape. Moreover, an elastic material should be selected which exerts the right amount of force on the liquid to be buffered, and has a sufficient contraction speed. The material of the layer which provides resistance to the liquid can be selected for each specific liquid. Although this materialneed not provide any elastic force, it should be able to follow the expansion and contraction of the elastic layer.

[0007] In an embodiment, the elastic buffer bag may define an internal volume and may have an opening in fluid communication with the pump, and the first layer may be an inner layer and the second layer may at least partially envelope the first layer. In this way the elastic outer layer is free to expand when the buffer bag is filled with liquid.

[0008] In a further embodiment, the first and second layers may be integrally formed, in particular by 2C injection molding. This provides a strong bond between the layers, while also reducing the number of separate parts and the effort of assembling the device. The buffer bag may be formed by first injection molding an outer layer and then injection molding an inner layer within that outer layer. Alternatively, the inner layer may be injection molded first, and then the outer layer may be injection molded over the inner layer.

[0009] In an alternative embodiment, the first and second layers may be individual parts which may be mutually connected. This provides a greater degree of freedom in design and the selection of materials for the individual layers.

[0010] In that case, the first and second layers may be connected by mechanical connecting means, like e.g. a snap connection or a tight fit. Such a mechanical connection may be releasable.

[0011] Additionally or alternatively, the first and second layers may be connected by an adhesive. This allows a strong bond over a relatively large surface area.

[0012] It is also conceivable that the first and second layers are connected by welding. This is a relatively fast and easy way of connecting the layers.

[0013] In an embodiment, the first layer may comprise a thermoplastic elastomer (TPE) or a natural or synthetic rubber. These classes of materials may provide good resistance to various liquids.

[0014] In a further embodiment, the thermoplastic elastomer of the first layer may comprise a thermoplastic vulcanizate (TPV or TPE-V). This class of material provides good resistance to a large group of liquids, while still providing sufficient stretch to expand and contract with the material of the second layer. A suitable choice for a synthetic rubber for the first layer may be e.g. neoprene, NBR, SBR or EPDM, all of which couple good resistance to various liquids with sufficient stretchability.

[0015] In an embodiment, the second layer may comprise a thermoplastic elastomer (TPE) or a natural or synthetic rubber, in particular a silicone rubber. These classes of materials may provide good elasticity.

[0016] In a further embodiment, the thermoplastic elastomer of the second layer comprises a recyclable material, in particular a styrene block copolymer (TPS or TPE-S). This material couplesgood elastic properties, including elastic force, stretch, material memory and contraction speed, with the ability to be recycled with the other plastics used in the liquid dispensing device.

[0017] In an embodiment, the first layer may have a thickness which may be between 5 - 45 %, in particular between 10 - 40 %, more in particular between 15 - 35 %, even more in particular between 20 - 30 %, and most in particular approximately 25 % of a total wall thickness of the elastic buffer bag. The first layer may be relatively thin, since its main function is to shield the second layer from direct contact with the liquid. In fact, provided the first layer is impermeable to the liquid, it essentially only has to form an impenetrable coating on the second layer to serve its function.

[0018] In an embodiment, the second layer may have a thickness which may be between 55 - 95 %, in particular between 60 - 90 %, more in particular between 65 - 85 %, even more in particular between 70 - 80 %, and most in particular approximately 75 % of a total wall thickness of the elastic buffer bag. By having a relatively thick second layer, a relatively large part of the wall thickness may be dedicated to the function of providing elasticity and a return force to cause the buffered liquid to eventually flow towards the nozzle.

[0019] In an embodiment, the elastic buffer bag may be arranged at least partially in the piston of the pump. By arranging the buffer bag in the piston, efficient use is made of the available space, thus resulting in a compact design.

[0020] In another embodiment, which further comprises means for connecting the dispensing device to the container, the elastic buffer bag may extend at least partially past the connecting means towards an interior of the container. By at least partially arranging the buffer bag in the interior of the container, efficient use is made of the available head space, thus resulting in a compact design.

[0021] In yet another embodiment, the elastic buffer bag may extend substantially in alignment with or parallel to the pump chamber. By arranging the buffer bag in alignment with the pump chamber, short and straight channels can be used to connect the buffer bag with the pump chamber, thus minimizing the volume therebetween. Moreover, the arrangement in line with or parallel to the pump chamber allows sufficient room for providing a relatively large buffer bag.

[0022] 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.

[0023] In a further embodiment the neck of the elastic buffer bag may be clamped between the inner peripheral edge of the buffer housing and the core element. In this way the core element serves a double purpose.

[0024] In such an embodiment, the core element may substantially 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 pumpstroke 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.

[0025] 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.

[0026] In an 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.

[0027] 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.

[0028] 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.

[0029] In an embodiment, 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”.

[0030] 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.

[0031] 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 pumpstroke. The volume of the elastic buffer bag in its fully expanded state is limited only by the interior volume of the buffer housing. The dimensions of the elastic buffer bag are selected such that when it is expanded to the point where it is restricted by the buffer housing, its fully expanded state in the sense of the present disclosure, the material of the bag is still (well) within its elastic range. In that way liquid may be buffered at a relatively lower pressure.

[0032] It is also conceivable that the bag is dimensioned such that its internal volume, when restricted by the buffer housing, 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 buffer housing could be two times, four times, seven times or even ten times the displacement volume of the pump. For instance, the internal volume of the bag when expanded to come into contact with the buffer housing could be 1, 2, 3, 4 or even 5 ccm, while the displacement volume of the pump could be 0.5 ccm. An oversized buffer bag that may potentially be expanded to such dimensions will lead to a very gradual pressure build-up when it is partially filled during a pump stroke.

[0033] In an embodiment, the liquid dispensing device may further comprise a pump outlet valve arranged between the pump and the buffer. This allows dispensing of the liquid to continue even when the pump is no longer actuated, since the pump outlet valve, which is a one-way valve, prevents the liquid stored in the buffer bag from flowing back into the pump chamber.

[0034] Consequently, the liquid stored in the buffer can only flow past the outlet valve and through the nozzle. This concept is identified as “continuous dispensing” or “continuous spray”.

[0035] In a liquid dispensing device which is configured for continuous spray, a displacement volume of the pump may be between 0.15 and 3.0 ccm, preferably between 0.2 and 2.5 ccm and more preferably between 0.3 and 2.0 ccm, and a difference in volume between a fully expanded state and a relaxed state of the elastic buffer bag may be between 0.5 and 15 times of the displacement volume of the pump, preferably between 0.7 and 12 times the displacement volume and more preferably between 1 and 10 times the displacement volume.

[0036] In such a continuous liquid dispensing device it is important that buffer capacity is sufficient to accommodate the amount of liquid that is displaced during consecutive pump strokes at a certain frequency. This is because part of the total volume displaced by the pump will be dispensed via the nozzle, while another part will be stored in the buffer, since the nozzle flow rate is lower than the total flow rate offered by the pump.

[0037] The invention further relates to a system for dispensing a liquid, which comprises a container and a liquid dispensing device of the type described above connected to the container.

[0038] The invention also relates to an elastic buffer bag for use in a liquid dispensing device of the type described above.And finally, the invention relates to a method of manufacturing an elastic buffer bag for use in a liquid dispensing device. In accordance with the invention, this method comprises the steps of forming a first layer comprising a material having good resistance to a liquid to be dispensed, forming a second layer comprising a material having a predetermined amount of elasticity, and mutually connecting the first and second layers. As discussed above, manufacturing the elastic buffer bag in this way allows various advantageous characteristics of different materials to be combined.

[0039] Further embodiments of this manufacturing method are defined in dependent claims 20-32. The invention will now be elucidated by way of some exemplary embodiments, with reference being made to the annexed drawings, in which:

[0040] 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;

[0041] Fig. 2 is a front view of the system of Fig. 1 ;

[0042] Fig. 3 is a hydraulic scheme of a “direct stop” version of the liquid dispensing device; Fig. 4 is a hydraulic scheme of a “continuous spray” version of the liquid dispensing device;

[0043] Fig. 5 is an enlarged scale cross-sectional view along the lines V-V in Fig. 2, showing the liquid dispensing device at rest, when the elastic buffer bag is empty;

[0044] Fig. 6 is a view corresponding with Fig. 5, showing the device during dispensing, when the elastic buffer bag is filled;

[0045] Fig. 7 is a view corresponding with Figs. 5 and 6, showing the device at the end of dispensing, when the elastic buffer bag has been emptied;

[0046] Fig. 8 is a perspective view showing a piston and elastic buffer bag of the liquid dispensing device of Figs. 5-7;

[0047] Fig. 9 is a cross-sectional view along the lines IX-IX in Fig. 8;

[0048] Fig. 10 is a view corresponding to Fig. 5, showing a second embodiment of the dispensing device of the invention in its position of rest with an empty elastic buffer bag;

[0049] Fig. 11 is a view corresponding to Fig. 10, showing the dispensing device with the piston in its lowermost position and the elastic buffer bag completely filled;

[0050] Fig. 12 is a view corresponding to Figs. 5 and 10, showing a third embodiment of the dispensing device of the invention in its position of rest;

[0051] Fig. 13 is a view corresponding to Fig. 12, showing the dispensing device with the piston at the end of its stroke and the elastic buffer bag completely filled;

[0052] Fig. 14 is a view corresponding to Figs. 5, 10 and 12, showing a fourth embodiment of the dispensing device of the invention in its position of rest;Fig. 15 is a view corresponding to Fig. 14, showing the dispensing device with the piston at the end of its stroke and the elastic buffer bag completely filled;

[0053] Fig. 16 is a view corresponding to Figs. 5, 10, 12 and 14, showing a fifth embodiment of the dispensing device of the invention in its position of rest;

[0054] Fig. 17 is a view corresponding to Fig. 16, showing the dispensing device with the piston at the end of its stroke and the elastic buffer bag completely filled;

[0055] Fig. 18 is a flow diagram illustrating steps of a method of manufacturing an elastic buffer bag; and

[0056] Fig. 19 is a flow diagram illustrating an alternative manufacturing method.

[0057] 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).

[0058] 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. 5-7). 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).

[0059] 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.

[0060] The liquid dispensing device 3 also comprises a buffer 9 which is in fluid communication with the pump 5. Buffer 9 comprises an elastic buffer bag 10 which defines an expansible volume. In accordance with the invention, the elastic buffer bag 10 comprises a first layer 10A and a second layer 10B. The first layer 10A comprises a material having good resistance to the liquid to be dispensed, while the second layer 10B comprises a material having a predetermined amount of elasticity, as will be described in more detail below.

[0061] In the illustrated embodiment, the elastic buffer bag 10 defines an internal volume Vb and the first layer 10A is an inner layer, while the second layer 10B envelopes the first layer 10A and constitutes an outer layer. The inner and outer layers 10A, 10B may be bonded over a large part of, or even their entire surface area, e.g. by an adhesive or by welding. Alternatively, the inner and outer layers 10A, 10B may be integrally formed, e.g. by 2C injection molding. On the other hand,the inner and outer layers 10A, 10B may also be mechanically coupled, e.g. by clamping or a snap fit.

[0062] 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. As shown here, 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.

[0063] 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.

[0064] 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. 5.

[0065] 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).

[0066] 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.

[0067] 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 the illustrated embodiment, the elastic buffer bag 10 is arranged in the piston 7. The elastic buffer bag 10 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.

[0068] 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. 5 and 7, 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.

[0069] The first layer 10A of the elastic buffer bag 10 may comprise a thermoplastic elastomer (TPE) or a or a natural or synthetic rubber. In particular, the thermoplastic elastomer of the first layer may comprise a thermoplastic vulcanizate (TPV or TPE-V). This class of material provides good resistance to a large group of liquids, while still providing sufficient stretch to expand and contract with the material of the second layer. A suitable choice for a synthetic rubber for the first layer may be e.g. neoprene, NBR, SBR or EPDM, all of which couple good resistance to various liquids with sufficient stretchability.

[0070] The second layer 10B of the elastic buffer bag 10 may comprise 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 thermoplastic elastomer of the second layer 10B may comprise a recyclable material, in particular a styrene block copolymer (TPS or TPE-S). This material couples good elastic properties, including elastic force, stretch, material memory and contraction speed, with the ability to be recycled with the other plastics used in the liquid dispensing device 3. A suitable material for the elastic buffer bag 10 is Thermolast® K from Kraiburg

[0071]

[0072] In the illustrated embodiments, the first layer 10A may have a thickness which is between 5 - 45 %, in particular between 10 - 40 %, more in particular between 15 - 35 %, even more in particular between 20 - 30 %, and most in particular approximately 25 % of a total wall thickness of the elastic buffer bag 10. On the other hand, the second layer 10B may have a thickness which is between 55 - 95 %, in particular between 60 - 90 %, more in particular between 65 - 85 %, evenmore in particular between 70 - 80 %, and most in particular approximately 75 % of a total wall thickness of the elastic buffer bag 10.

[0073] 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.

[0074] 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.

[0075] As can be seen from Figs. 5 and 6, 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 material of the multilayer wall of the buffer bag 10. The difference in volume between the expanded state of the elastic buffer bag 10 shown in Fig.

[0076] 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.

[0077] 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. 5, 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.

[0078] 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. 6), 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.

[0079] 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. 6). 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.

[0080] 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. 7). 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.

[0081] 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 itspressure will fall below the cracking pressure of the pre-compression valve 13 (Fig. 5). The abrupt closure of the pre-compression valve 13 will prevent any dripping.

[0082] In an alternative embodiment of the liquid dispensing device 103, pump chamber 106 has an axis P which is parallel to the axis I of inlet channel 114 (Figs. 10, 11). Piston 107 is connected to actuator 108 by a pin 148 in an oblong aperture 162, which transforms the pivoting movement of the actuator 108 in the direction of arrow T into vertical reciprocating movement of the piston 107 as indicated by arrow R. An inlet channel 149 runs from inlet opening 116 to 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.

[0083] Buffer 109 is again arranged in buffer housing 154 and comprises an elastic buffer bag 110 and a core element 140.

[0084] In this embodiment, pump outlet opening 119 leads to channel 155 which directs liquid into both the bore 143 and a vertical intermediate channel 151. Bore 143 again leads to groove 145 of core element 140, while vertical intermediate channel 151 leads to valve chamber 120. In valve chamber 120, dome valve 113 once again sealingly abuts valve seat 123 surrounding outlet channel 124. The outlet channel 124 guides the liquid to the orifice 125 of the nozzle 112.

[0085] In this embodiment connector 104 is integrally formed with liquid dispensing device 103 and includes inwardly protruding cams 129 which are configured for cooperation with bayonet provisions on the container neck (not shown).

[0086] 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. 5-7. Here again, any liquid that cannot be dispensed through nozzle 112 at the rate at which it is moved by pump 105 being operated by a user, will be stored in buffer 109 by elastic deformation of buffer bag 110, as shown in Fig. 11. The liquid is then released from buffer 109 to vertical intermediate channel 151 and onwards to nozzle 112 when the user maintains piston 107 n its lowermost position by keeping actuator 108 depressed.

[0087] In the embodiments discussed above, the internal volume Vb of the elastic buffer bag 10, 110 has been shown to be in open communication with the pump chamber 6, 106, resulting in dispensing of liquid being interrupted as soon as a user stops operating the pump 5, 105. This concept is known as “direct stop” and is illustrated by the hydraulic scheme of Fig. 3.

[0088] A third embodiment of the liquid dispensing device 203 comprises a buffer 209 which faces the pump 205. The elastic buffer bag 210 extends substantially in alignment with the pump chamber 206. In the shown embodiment the elastic buffer bag 210 is arranged in a buffer housing 254 which is arranged substantially opposite the pump chamber 206. In the illustrated embodiment, a cross-sectional area of the buffer housing 254 fully overlaps with a cross-sectional area of the pump chamber 206.In this embodiment, the opening 211 of the elastic buffer bag 210 is arranged in an open end 235 of the buffer housing 254 which is connected with the pump chamber 206 by the horizontal channel 255 and the pump outlet opening 219 in the end wall 253 of the pump chamber 206.

[0089] This embodiment of the liquid dispensing device 203 further includes a pump outlet valve 263 which is arranged between pump 205 and the buffer 209 (Figs. 12 and 13). The pump outlet valve 263 closes off the pump outlet opening 219 and isolates the pump chamber 206 from the channel 255 leading to both the buffer 209 and the central channel 251. In the illustrated embodiment the pump outlet valve 263 comprises a disk, like the pump inlet valve 217. The diskshaped pump outlet valve 263 is movable with respect to an annular valve seat 264 surrounding the pump outlet opening 219.

[0090] Like the inlet valve 217, the pump outlet valve 263 is a one-way valve that opens and closes as a result of pressure differentials acting on the valve. The pump outlet valve 263 opens when pressure is built up in the pump chamber 206 during an inward pump stroke of the piston 207, allowing liquid to flow into the channel 255 and from there into the central channel 251 and into the buffer 209. The pump outlet valve 263 closes when the pressure in the pump chamber 206 drops during an outward suction stroke of the piston 207. The pump outlet valve 263 remains closed as long as the liquid pressure in the channel 255, the buffer 209 and the central channel 251 leading to the outlet valve 213 is higher than the pressure in the pump chamber 206. This allows dispensing of the liquid through the nozzle 212 to continue as long as the pressure in the buffer 209 is higher than the cracking pressure of the outlet valve 213. Such continuous dispensing resembles the function of an aerosol, without the need for a propellant. The general arrangement of a “continuous dispensing” device is illustrated by the hydraulic scheme of Fig. 4.

[0091] In order to allow dispensing to continue for some time after the user has stopped operating the trigger 208, the useful internal volume of the expansible buffer bag 210, i.e. the difference in volume between its expanded state and its relaxed state, must be balanced with the displacement volume of the pump 205. The ratio between the effective internal volume of the elastic buffer bag 210 and the displacement volume of the pump 205 may vary between 0.5 and 15, and preferably between 0.7 and 12. Most preferable, this ratio varies between 1 and 10.

[0092] As can be seen by comparing the embodiment of Figs. 12 and 13 with a fourth embodiment that is shown in Figs. 14 and 15 and that is a “direct stop” embodiment lacking a pump outlet valve, both the elastic buffer bag 210 and the buffer housing 254 of the “continuous dispensing” embodiment are larger than the corresponding elements of the “direct stop” embodiment. In the illustrated embodiment the diameter Di of the buffer housing 154 is the same as that of the buffer housing 354 of the “direct stop” liquid dispensing device, but it has a greater length. However, it is also conceivable that the diameter is greater than that of the buffer housing354 instead of or in addition to the greater length of the buffer housing 254. The difference in dimensions between the buffers 209 and 309, and the corresponding difference in the size of the shrouds 231, 331 are the main features distinguishing the “continuous dispensing” and “direct stop” embodiments, in addition to the presence of the pump outlet valve 263 in the third embodiment and the lack thereof in the fourth embodiment.

[0093] The third and fourth embodiments resemble the first and second embodiments of Figs. 5-11 in all further aspects.

[0094] It should be noted that instead of being completely aligned with the pump chamber as in the third and fourth embodiments, the buffer may also be parallel but offset relative to the pump chamber. For instance, the buffer chamber could be arranged opposite the pump, at the position where the outlet valve 13 is shown in Figs. 5-7. In that case the outlet valve would be moved to a position between the offset buffer chamber and the nozzle that is closer to the nozzle than the valve position shown in Figs. 12-15. The cross-sectional area of the buffer chamber would then only partially overlap with the cross-sectional area of the pump chamber. Alternatively, the buffer could be arranged above and parallel to the pump chamber, in the space defined between the outlet channel and the top of the shroud. The buffer housing could be oriented with its closed end towards the nozzle and its open end facing in the same direction as the pump outlet opening. In that case there would be no overlap between the cross-sectional areas of the buffer chamber and the pump chamber.

[0095] A fifth embodiment of the liquid dispensing device 403 resembles the second embodiment shown in Figs. 10 and 11, but includes a pump outlet valve 463 which is arranged between the pump 405 and the buffer 409 (Figs. 16 and 17). Like in the third embodiment of Figs. 12 and 13, the pump outlet valve 463 closes off the pump outlet opening 419 and isolates the pump chamber 406 from the channel 455 leading to both the buffer 409 and the intermediate channel 451. In this way liquid may again be dispensed through the nozzle 412 as long as the pressure in the buffer 409 is higher than the cracking pressure of the outlet valve 413. Here again, both the elastic buffer bag 410 and the buffer housing 454 of the “continuous dispensing” embodiment are larger than the corresponding elements of the “direct stop” embodiment of Figs. 10 and 11. In the illustrated embodiment the diameter Di of the buffer housing 454 has been maintained, but its length has been increased. As mentioned before, it is also conceivable that the diameter is increased instead of or in addition to lengthening the buffer housing 454. The ratio between the effective internal volume of the elastic buffer bag 410 and the displacement volume of the pump may again vary between 0.5 and 15, and preferably between 0.7 and 12. Most preferable, this ratio varies between 1 and 10.

[0096] The fifth embodiment resembles the previous embodiments of Figs. 5-15 in all further aspects.The elastic buffer bag may be manufactured by a method 1000 as shown in Fig. 18. In a first step 1001 the first layer 10A is formed. This layer, which comprises a material having good resistance to a liquid to be dispensed, may be formed by injection molding, although other techniques are also conceivable.

[0097] In a second step 1002 the second layer 10B is formed. This layer, which comprises a material having a predetermined amount of elasticity, may also be formed by injection molding or by another technique.

[0098] In a third step 1003 the first layer 10A and the second layer 10B may be mutually connected to form the actual elastic buffer bag 10. This may be done by mechanical means, by an adhesive or by welding, although other techniques are also conceivable.

[0099] The elastic buffer bag 10 may eventually be mounted in a liquid dispensing device 3 in a final step 1004.

[0100] In an alternative method 2000 (Fig. 19) the first and second layers 10A, 10B may be manufactured by 2C injection molding. In this method, the first layer 10A may be formed in a first injection molding step 2001 by injecting a material having good resistance to a liquid to be dispensed into a mold. Then the second layer 10B may be formed by injecting a material having a predetermined amount of elasticity into the mold in a second step 2002. The elastic buffer bag 10 that is formed after performing these steps may then again be mounted in a liquid dispensing device 3 in a final step 2003.

[0101] The order in which the first and second layers 10A, 10B are injection molded may vary. The first layer 10A, which will be the inner layer of the buffer bag 10, may be molded first, and then the second layer 10B, which will form the outer layer of the buffer bag 10, may be overmolded over the first layer. Alternatively, the second layer 10B may be molded first, and then the first layer 10A may be molded in the second layer. In that case the method steps 2001 and 2002 will be reversed.

[0102] 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

Claims1. 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, the buffer comprising an elastic buffer bag defining an expansible volume;- 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 elastic buffer bag comprises at least two layers, the at least two layers including a first layer comprising a material having good resistance to the liquid to be dispensed and a second layer comprising a material having a predetermined amount of elasticity.

2. Liquid dispensing device as claimed in claim 1 , wherein the elastic buffer bag defines an internal volume and has an opening in fluid communication with the pump, and wherein the first layer is an inner layer and the second layer at least partially envelopes the first layer.

3. Liquid dispensing device as claimed in claim 1 or 2, wherein the first and second layers are integrally formed, in particular by 2C injection molding.

4. Liquid dispensing device as claimed in claim 1 or 2, wherein the first and second layers are individual parts which are mutually connected.

5. Liquid dispensing device as claimed in claim 4, wherein the first and second layers are connected by mechanical connecting means.

6. Liquid dispensing device as claimed in claim 4 or 5, wherein the first and second layers are connected by an adhesive.

7. Liquid dispensing device as claimed in any one of claims 4-6, wherein the first and second layers are connected by welding.

8. Liquid dispensing device as claimed in any one of the preceding claims, wherein the first layer comprises a thermoplastic elastomer (TPE) or a natural or synthetic rubber.

9. Liquid dispensing device as claimed in claim 8, wherein the thermoplastic elastomer of the first layer comprises a thermoplastic vulcanizate (TPV or TPE-V).

10. Liquid dispensing device as claimed in any one of the preceding claims, wherein the second layer comprises a thermoplastic elastomer (TPE) or a natural or synthetic rubber, in particular a silicone rubber.

11. Liquid dispensing device as claimed in claim 10, wherein the thermoplastic elastomer of the second layer comprises a recyclable material, in particular a styrene block copolymer (TPS or TPE-S).

12. Liquid dispensing device as claimed in any one of the preceding claims, wherein the first layer has a thickness which is between 5 - 45 %, in particular between 10 - 40 %, more in particular between 15 - 35 %, even more in particular between 20 - 30 %, and most in particular approximately 25 % of a total wall thickness of the elastic buffer bag.

13. Liquid dispensing device as claimed in any one of the preceding claims, wherein the second layer has a thickness which is between 55 - 95 %, in particular between 60 - 90 %, more in particular between 65 - 85 %, even more in particular between 70 - 80 %, and most in particular approximately 75 % of a total wall thickness of the elastic buffer bag.

14. Liquid dispensing device as claimed in any one of the preceding claims, wherein the elastic buffer bag is arranged at least partially in the piston of the pump.1915. Liquid dispensing device as claimed in any one of claims 1-13, further comprising means for connecting the dispensing device to the container, wherein the elastic buffer bag extends at least partially past the connecting means towards an interior of the container.

16. Liquid dispensing device as claimed in any one of claims 1-13, wherein the elastic buffer bag extends substantially in alignment with or parallel to the pump chamber.

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

18. Elastic buffer bag for use in a liquid dispensing device as claimed in any one of claims 1-16.

19. Method of manufacturing an elastic buffer bag for use in a liquid dispensing device, comprising:- forming a first layer comprising a material having good resistance to a liquid to be dispensed;- forming a second layer comprising a material having a predetermined amount of elasticity; and- mutually connecting the first and second layers.

20. Method as claimed in claim 19, wherein the elastic buffer bag defines an internal volume and has an opening, and wherein the first layer is an inner layer and the second layer is arranged such that it at least partially envelopes the first layer.

21. Method as claimed in claim 19 or 20, wherein the first and second layers are each formed by injection molding.

22. Method as claimed in any one of claims 19-21, wherein the first and second layers are integrally formed, in particular by 2C injection molding.2023. Method as claimed in any one of claims 19-21, wherein the first and second layers are individually formed and are mutually connected after being formed.

24. Method as claimed in claim 23, wherein mutually connecting the first and second layers comprises mechanically connecting the first layer to the second layer.

25. Method as claimed in claim 23 or 24, wherein mutually connecting the first and second layers comprises arranging an adhesive between the first and second layers.

26. Method as claimed in any one of claims 23-25, wherein mutually connecting the first and second layers comprises welding the first layer to the second layer.

27. Method as claimed in any one of claims 19-26, wherein the first layer is formed from a thermoplastic elastomer (TPE) or or a natural or synthetic rubber.

28. Method as claimed in claim 27, wherein the thermoplastic elastomer of the first layer comprises a thermoplastic vulcanizate (TPV or TPE-V).

29. Method as claimed in any one of claims 19-28, wherein the second layer is formed from a thermoplastic elastomer (TPE) or a natural or synthetic rubber, in particular a silicone rubber.

30. Method as claimed in claim 29, wherein the thermoplastic elastomer of the second layer comprises a recyclable material, in particular a styrene block copolymer (TPS or TPE-S).

31. Method as claimed in any one of claims 19-30, wherein the first layer is formed with a thickness which is between 5 - 45 %, in particular between 10 - 40 %, more in particular between 15 - 35 %, even more in particular between 20 - 30 %, and most in particular approximately 25 % of a total wall thickness of the elastic buffer bag.2132. Method as claimed in any one of claims 19-31, wherein the second layer is formed with a thickness which is between 55 - 95 %, in particular between 60 - 90 %, more in particular between 65 - 85 %, even more in particular between 70 - 80 %, and most in particular approximately 75 % of a total wall thickness of the elastic buffer bag.

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