WO2017064621A1

WO2017064621A1 - Fluid dispenser

Info

Publication number: WO2017064621A1
Application number: PCT/IB2016/056082
Authority: WO
Inventors: Mark Brouwer
Original assignee: Airopack Technology Group Ag
Priority date: 2015-10-13
Filing date: 2016-10-11
Publication date: 2017-04-20

Abstract

A fluid dispenser comprising a container (12) configured for storing a liquid (14). An outlet valve (18) arranged on the container (12), configured to regulate the dis-pensing of the liquid (14). A hollow tube (22) formed from a hydrophilic membrane (60), having an first end (22a) which is linked to the outlet valve (18) so as to be able to communicate with a fluid outlet (20) and a second closed end (22b) within the container (12), wherein the hydrophilic membrane (60) is configured to pass liquid in preference to gas so that the liquid (14) flow from the container (12) through the hydrophilic membrane (60) into the hollow tube (22). Further the fluid dispenser comprising a high-pressure vessel (24) connected by a passageway (26) to the container (12) and a control valve (28) is arranged in the passageway (26), wherein the control valve (28) is configured to regulate the pressure inside the container (12).

Description

Fluid Dispenser

FIELD OF THE INVENTION The present invention relates to a fluid dispenser for dispensing a fluid. BACKGROUND OF THE INVENTION

Document WO2008/037969 A1 shows a fluid dispenser which functions in any orientation. The fluid dispenser is comprising a fluid path defined by a liquid reservoir, one or more membranes and an output. Means for pressurising the liquid reservoir, wherein the fluid path is arranged such that, when the output is in an open position a pressure differential induces a flow of liquid along the fluid path through the one or more membranes to the output. The one or more membranes and the liquid reservoir are arranged such that liquid in the reservoir is in contact with the membranes in substantially any orientation, and the one or more membranes are adapted to pass liquid in preference to gas. The pressure differential may be introduced by applying a pressure to the sidewalls of the device which may be flexible such that a user can squeeze the device.

Depending on the viscosity of the liquid in the container, the pore size of the membrane and the pressure differential between inside and outside of the container accrues a different liquid output. Because of various parameters the amount of emitted liquid is difficult to determine when the dispenser is activated. Moreover, the user has to pump-out the liquid from the container for example by squeezing the device. Further depending on the expended forces to the sidewalls more or less fluid will be emitted. Especially for elderly or weak persons it may be too arduous to squeeze the device. OBJECT OF THE INVENTION

The object of the present invention is to provide a fluid dispenser for dispensing fluid in any position at a constant liquid output without any exertion.

This object is solved by the subject matter of the independent claims.

According to embodiments of the invention, the liquid fluid dispenser is comprising a container, configured for storing a liquid. An outlet valve is arranged on the con- tainer, configured to regulate the dispensing of the liquid. A hollow tube is formed from a hydrophihc membrane, having an first end which is linked to the outlet valve so as to be able to communicate with a fluid outlet and a second closed end within the container, wherein the hydrophihc membrane is configured to pass a liquid in preference to gas, so that the liquid flows from the container, through the hydro- philic membrane and into the hollow tube. Further a high-pressure vessel is provided, connected by a passageway to the container wherein a control valve is arranged in the passageway. The control valve is configured to regulate the pressure inside the container. The liquid which is stored in the container may pass the hydrophihc membrane in preference to gas, air or any other propellant which is in the container. Therefore the hollow tube, which is formed by the hydrophihc membrane may only be in contact with the liquid at a specific position, hence the liquid instead of gas passes the hydrophihc membrane. The liquid may travel from any position in the container, where it is in contact with the surface of the hydrophihc membrane in the hollow tube.

The first end of the hollow tube is connected to an outlet valve, so that the fluid may travel from the container into the hollow tube, from the hollow tube to the outlet valve and then to the fluid outlet. Through the outlet valve a fluid flow may be controllable, such that the fluid only flows out, when the outlet valve is activated. The second end of the hollow tube may be closed, such that the liquid may not run out of the hollow tube at the second end. Furthermore, gas cannot enter into the hollow tube, when the second end is closed. The pressure in the container may press the liquid to the outlet valve. By activating the outlet valve, liquid will flow out of the container through the outlet valve and the fluid outlet. Since the liquid in the container will be reduced, the pressure in the container drops too. The high-pressure vessel may store additional gas, such that the amount of outputted liquid, respectively the reduction of the pressure in the container, may be reconstituted by gas from the high-pressure vessel. The control valve may control the output of gas from the high-pressure vessel into the container. Through the controlling of the pressure in the container a constant liquid flow may result at the fluid outlet, since the hydrophilic membrane may be adapted to the liquid and the pressure in the container.

According to another embodiment of the invention, the fluid dispenser comprises a propellant. The propellant may be liquefied in the high pressure vessel. Through a propellant the fluid may be under pressure in the container, such that the liquid flows from the hollow tube, to the outlet valve and the fluid outlet. A propellant may be for example propane, butane, carbon dioxide, nitrogen, air or any other substance which does not chemically react with the liquid in the container. A liquefied propellant may use less volume in the high pressure vessel. The liquefied propellant in the high pressure vessel should vaporize by the pressure which exist inside the container, hence no liquefied propellant passes the hydrophilic membrane.

According to a further embodiment of the fluid dispenser, the hollow tube is flexible and has a length which is longer than the height of the container. Through a length of the hollow tube which is longer than the height of the container the hollow tube may contact every level inside the container, such that the hollow tube can be also in contact with the fluid in the container when the container is nearly empty. The flexibility of the hollow tube makes it possible, that the hollow tube may be arranged in a meandering or in a serpentine pattern, respectively in any other pattern. Through the flexibility of the hollow tube, the hollow tube may also proceed in a cylindrical shape belong the wall of the container.

According to an embodiment of the fluid dispenser, the hydrophilic membrane has a pore size less than 30 nanometres respectively the hydrophilic membrane is a capillary membranes. Through the small size of the pores from the hydrophilic membrane, the liquid in the container passes the membrane in preference to the gas in the container. The hydrophilic membrane may have a capillary action or any other effect which results that the liquid passes the membrane privileged to the gas.

According to an embodiment of the fluid dispenser, the container and the high- pressure vessel are substantially cylindrical and share a common axis. A cylindrical shape enables a high pressure in the container and in the high-pressure vessel with minor material input and costs. An arrangement of the container and the high- pressure vessel on a common axis simplifies the production, transport and distribution of the fluid dispenser.

According to an embodiment of the fluid dispenser, the control valve is configured to maintain a constant predetermined pressure inside the container. The pore size of the hydrophilic membrane may be adapted or adjusted to the liquid and the pressure in the container, such that a continuous and constant liquid flow results at the fluid outlet. According to an embodiment of the fluid dispenser, the control valve comprises a first piston and a plunger which are connected by a rod and the control valve is movable arranged on a longitudinal axis of the control valve. The plunger has a conical shape, along the longitudinal axis of the control valve, configured to regulate a gas flow from the high-pressure vessel. Because of the conical shape, the plunger shall only be moved by a short distance to open the control valve and to enable the propellant to flow from the high-pressure vessel to the container. Therefore the control valve may be fine tuning the pressure in the container, such that a predetermined pressure may be constant in the container. According to an embodiment of the fluid dispenser, the plunger has a front surface, at right angles to the longitudinal axis of the control valve, with an area size AR. The piston has a front surface, at right angles to the longitudinal axis of the control valve, with an area size Av and the area size AR is larger than the area size Av, preferably the area size of AR is ten times larger than the area size of Av. Pressure is a force acting per unit area or a pressure is a force applied to a surface. Preferably the area size of the front surface of the first piston is ten time larger compared to the size of the front surface of the plunger.

According to another embodiment of the fluid dispenser a ring-cylinder which com- prises the opening of the high-pressure vessel, is arranged at the outlet of the high- pressure vessel, whereas the plunger has a conical shape and the opening has a commensurate tapered shape.

According to a further embodiment a second piston is movable arranged in the container and is configured to separate the container in a first chamber and in a second chamber, wherein the high-pressure vessel is connected over the control valve with the second chamber.

According to another embodiment the second piston is configured to separate the first chamber and in the second chamber in a gas tight manner.

Further advantages of the invention can be derived from the dependent claims and from the description below. BRIEF DESCRIPTION OF THE FIGURES

In the following, exemplified embodiments of the present invention are described in more details with reference to the figures, in which:

Fig. 1 illustrates a sectional view of a fluid dispenser;

Fig. 2 illustrates a sectional view of the fluid dispenser with a plunger;

Fig. 3 shows a sectional view of a control valve in a closed position;

Fig. 4 shows a sectional view of the control valve in an open position;

Figure 1 shows a sectional view of a fluid dispenser 10. The fluid or liquid dispenser 10 comprises a container 12 which is a pressure container configured for a pressure between 1 bar to 3 bar. Preferably the container 12 is configured for a pressure of 2 bar. The container 12 may comprise a pressurized gas for storing the content under pressure and holding the pressure constant in the container 10. The container 12 may have a cylindrical shape, for easy production and delivering.

The container 12 is configured for storing a liquid 14 and a propellant 16. The liquid 14 is a fluid or foamable substance for example a shaving cream or gel, a soap, a lubricant (e.g. oil) or any other liquid or foamable substance which is suitable for storing in a container and dispensing with a fluid dispenser. The propellant 16 may be for example propane, butane, carbon dioxide, nitrogen, air or any other substance which does not chemically react with the liquid in the container 12. The propellant 16 may also be used to foam the liquid 14 for example when the liquid 14 will be dispensed.

On the container 12 an outlet valve 18 is arranged. The outlet valve 18 is fitted gas proof to the container 12. The outlet valve 18 may be arranged on the upper side of the container 12. The output valve 18 is configured to regulate the dispensing of the liquid 14. The outlet valve 18 is arranged between a hollow tube 22 and a fluid outlet 20. The outlet valve 18 is integrated in a passageway or connection from the container 12 to the environment. The outlet valve 18 can be superimposed or integrated in the container 12. The outlet valve 18 controls the liquid flow from the container 12 to the fluid outlet 20. The outlet valve 18 will be activated with an actuator 56. When the outlet valve 18 is actuated liquid 14 travels from the container 12 through the hydrophilic membrane into the hollow tube 22, further through the outlet valve 18 and to the fluid outlet 20, where the fluid is dispensed. By activating the outlet valve 18, the output of liquid 14 is controlled, such that liquid 14 from the container 12 can be dispensed without any effort. The outlet valve 18 may also be configured to mix liquid 14 with propellant 16 for example to generate a foam. Through activating the outlet valve 18 the liquid 14 and the propellant 16, as the case may be, flow from the inside of the container 12 via the outlet valve 18 to the fluid outlet 20. The liquid 12 will be dispensed at the fluid outlet 20 as a fluid, a liquid, an aerosol, a gel, a foam or any other consistence of a substance.

The outlet valve 18 has only two positions such that the flow of liquid 14 is just activated or interrupted. The outlet valve 18 can also control the flow of liquid 14 smoothly, such that by pressing the actuator 56 with a higher force, more liquid 14 will escape from the container 12 via the outlet valve 18 to the fluid outlet 20, than by pressing the actuator 56 with a lower force.

The hollow tube 22 can be formed from a hydrophilic membrane 60. The hollow tube 22 has a first end 22a which is linked to the outlet valve 18 so as to be able to communicate with the fluid outlet 20. Through the fluid outlet 20 liquid 14 may travel or flow from the inside of the container 12 across the hollow tube 16 and the outlet valve 18 to the outside or environment of the container 12. The hollow tube 22 can be linked, coupled or connected directly to the outlet valve 18 or via an additional linker, which extends the connection between the hollow tube 22 and the outlet valve 18. A linker may also mix propellant 16 to the liquid 14 from the hollow tube 22, such that the liquid will be foamed. A second closed end 22b of the hollow tube 22 is within the container 12. The second closed end 22b is closed ga proof, such that the propellant 16 or any other gas in the container cannot penetrate the hollow tube 22 at the second end 22b. For example the second end 22b closes the hollow tube 22 by welding or glueing. The hollow tube 22 may have a length which is longer than the height of the container 12, such that the hollow tube 22 extends over the whole height of the container 12 and the liquid 14 will be at some place in contact with the hollow tube 22, when the container 12 is in an upright position. In a preferred embodiment the hollow tube 22 has a length which is equal than twice of the height of the container 12 plus the diameter of the container 12. The hollow tube 22 can be arranged in a U shaped form, such that the hollow tube 22 is arrange downwards along one side wall of the container 12, close to the bottom of the container 12 and upwards along the opposite side wall. The hollow tube 22 may also be arranged in the container 12 in a cylindrical shape, such that the hollow tube 22 is in contact with the cylin- drical container wall along more or less the entire height of the cylinder. The hollow tube 22 can also be arranged in the container 12 in a helical shape along the entire height of the container 12. Through the cylindrical, helical or other arrangements of the hollow tube 22 the liquid 14 will be in contact at least at one place of the hollow tube 22, even when the container 12 is not in an upright position, for exam- pie when the container 12 or fluid dispenser 10 is in a diagonal position or when the container 12 or fluid dispenser 10 is nearly upside down.

The hydrophilic membrane 60 or hollow hydrophilic membrane is configured to pass a liquid 14 in preference to gas, for example the propellant 16, such that the liquid 14 flows from the liquid container 12 through the hydrophilic membrane 60 into the hollow tube 22. When liquid 14 is in contact with the hydrophilic membrane 60 at least at some place, than the liquid 14 flows through the hydrophilic membrane 60 into the hollow tube 22, such that gas will not flow in the hollow tube 22 as long as liquid 14 is in the hollow tube 22. The hydrophilic membrane 60 is a membrane which comprises pores, preferably very small pores with a size less than 30 nanometres [nm]. Preferably the size of the pores may be smaller than 20 nm or even smaller than 15 nm. In a special embodiment, the size of the pores can be smaller than 10 nm. The size of the pores depends on the viscosity of the liquid 14 in the container 12 which passes the hydrophilic membrane in preference to the propellant. Thus, the pore size can be adapted to the properties of the liquid 14 or to the properties of the propellant 16 in the container 12, such that the liquid 14 passes the hydrophilic membrane in preference to the propellant 16. The pressure in the container 12 depends on the size of the pores of the hydrophilic membrane 60, such that the pressure in the container 12 can be adapted to the size of the pores of the hydrophilic membrane 60. The hydrophilic membrane 60 can be a capillary membrane, such that the liquid 14 passes the hydrophilic membrane in preference to gas by a capillary effect. The liquid 14 may also flow through the hydrophilic membrane 60 into the hollow tube 22, when the pressure inside the hollow tube 22 is lower than the pressure in the container 12. The liquid 14 may have a viscosity which is adapted to the hydrophilic membrane 60. The fluid dispenser 10 further comprises a high-pressure vessel 24. The high- presser vessel 24 is fitted gas proof to the container 12. The high-pressure vessel 24 has a passageway 26 or a connection to the container 12. The high-pressure vessel 24 is arranged beneath the container 12, such that the lower side of the container 12 is open and the high-pressure vessel 24 - especially the upper part of the high-pressure vessel 24 - forms the bottom of the container 12. The lower side of the container 12 may also be closed with a bottom and the high-pressure vessel 24 can be arranged inside or outside the container 12. The high-pressure vessel 24 normally has a cylindrical shape. The container 12 and the high-pressure vessel 24 are substantially cylindrical and share a common longitudinal axis 48, which proceeds through the centre of the cylinder of the container 12 and through the centre of the cylinder of the high-pressure vessel 24.

The high-pressure vessel 24 is configured to stand a pressure between 2 bar to 12 bar. Preferably the high-pressure vessel 24 is configured for a pressure between 7 bar to 9 bar, in particular for a pressure of 8 bar. The propellant 16 in the high-pressure vessel 24 is pressurized higher than the pressure in the container 12. The propellant 16 can be stored with a pressure between 2 bar to 12 bar. Preferably, the propellant 16 is stored with a pressure between 7 bar to 9 bar, preferably at 8 bar. The high-pressure vessel 24 is filled with the propellant 16 through an opening in the bottom side of the high pressure vessel 24. The opening of the high-pressure vessel 24 is closed with a plug 44, after filling with propellant 16 with the predetermined pressure.

A control valve 28 is arranged in the passageway 26, wherein the control valve 28 is configured to regulate the pressure inside the container 12. The passageway 26 is a connection between the high-pressure vessel 24 and the container 12, such that the propellant 16 may flow from the high-pressure vessel 24 to the container 12.

The control valve 28 is arranged in the passageway 26, wherein the control valve 28 is configured to regulate the pressure inside the container 12, i.e. by regulating the gas flow from the high-pressure vessel 24 to the container 12. The control valve 28 is htus configured to maintain a constant predetermined pressure inside the container 12. The control valve 28 will open the passageway 26, when the pressure in the container 12 is lower than a predetermined pressure. If the control valve 28 opens the passageway 26, propellant 16 will flow from the high-pressure vessel 24 into the container 12 and the pressure in the container 12 rises to the predetermined pressure. When the predetermined pressure in the container 12 is achieved, the control valve 28 closes the passageway 26.

In Figure 1 the control valve 28 is in a closed position, such that no propellant 16 form the high-pressure vessel 24 flow into the container 12. The container 12 is filled approximately to a third with liquid 14. The liquid 14 has a higher relative density, than the propellant 16, such that the liquid 14 is in the lower part of the container 12 and the propellant 16 is in the upper part of the container 12. The propellant 16 fills approximately two-third of the container 12. The hollow tube 22 proceeds in a meandering pattern, respectively in a serpentine pattern in the container 12. The hollow tube 22 is in contact with the wall of the container 12. The second end of the hollow tube 22b is closed. The hollow tube 22 is at least partly in the liquid 14. Through the hydrophilic membrane 60 of the hollow tube 22 liquid may pass in preferences to gas through the wall of the hollow tube 22.

Figure 2 shows a sectional view of the fluid dispenser 10 with a second piston 46. The second piston 46 is movable arranged in the container 12 and is configured to separate the container 12 in a first chamber 12a and in a second chamber 12b. The first chamber of the container 12a is filled with liquid 14. The second chamber of the container 12b is filled with propellant 16. The high-pressure vessel 24 is connected by the passageway 26, in which the control valve 28 is arranged, with the second chamber 12b. The second piston 46 is configured to separate the first chamber 12a and in the second chamber 12b in a gas tight manner.

The control valve 28 is configured to regulate the pressure inside the container 12. If the outlet valve 18 is activated and liquid 14 flows from the first chamber of the container 12a to the fluid outlet 20 and will be emitted, than the pressure in the first chamber 12a drops. When the pressure in the first chamber 12a drops, than the second piston 46 will be moved by the pressure in the second chamber 12b. The pressure in the second chamber 12b may drop too, as the second piston 46 is moved upwards, until the pressure in the first chamber 12a and the second cham- ber 12b is equalized. The control valve 28 regulates the pressure in the second chamber of the container 12b by opening the passageway 26 to the high-pressure vessel 24, such that propellant flows from the high-pressure vessel 24 into the second chamber of the container 12b. The re-established pressure in the second chamber of the container moves the second piston 46 upwards until the pressure in the first chamber of the container 12a and in the second chamber of the container 12b is equalized. The pressure in the first chamber of the container 12a and the second chamber of the container 12b correlates with the predetermined pressure of the control valve 28. The liquid 14 for a fluid dispenser with the second piston 46 may have a higher viscosity than the fluid for a liquid dispenser without a second piston 46 ( as shown in figure 1 ). Through the hydrophilic membrane 60 of the hollow tube 22, which is configured to pass liquid in preference to gas, the liquid 14 can only be in contact with the hollow tube 22 at some place, such that liquid 14 flows into the hollow tube 22. Figure 3 shows the control valve 28 in a sectional view. The control valve 28 is configured to regulate a gas flow from the high-pressure vessel 24. The control valve 28 in figure 3 is in a closed position. The control valve 28 comprises a first piston 30 and a plunger 32 which are connected by a rod 34. The control valve 28 may be configured to prevent the pressure in the container 12 being dropped under a predetermined level.

The first piston 30 has a front surface, preferably at a right angle to the longitudinal axis 48 of the control valve 28. The front surface has a size AR. The first piston 30 comprises an upward rim 40 or the first piston 30 may also be flat at the front surface. The first piston 30 is arranged in a cylinder 36. The first piston 30 and the cylinder 36 form a reference chamber 42.

The reference chamber 42 will be formed through insertion of the first piston 30 into the cylinder 36. The reference chamber 42 is sealed gas proof to the environ- ment (for example towards the passageway 26) by an O-ring 58. The O-ring 58 is arranged in a ring-shaped groove on the rim 40 of the first piston 30. The first piston 30 and the cylinder 36 have a circular shape in direction of the longitudinal axis 48 of the control valve. The area size AR of the front surface comprises area sizes of the surface of the first piston 30 and of the rim 40, seen in a right angle to the longitudinal axis 48 of the control valve. The reference pressure (PR) in the reference chamber 42 produced a force (FRC) to the first piston 30 in the direction of the longitudinal axis 48 equal to the formula:

FRC - PR ^{' A}R The cylinder 36 may have a U-shaped form, in the sectional view of figure 3, wherein depending on the position of the high-pressure vessel 24 and the container 12, the U-shaped form of the cylinder 36 may be arranged upside down. In the wall of the cylinder 36 at least one vent 50 may be arranged. Through the vent 50, the propellant 16 flows out of the control valve 28 to the container 12. The first piston 30 and the plunger 32 which are connected by the rod 34 are movable arranged along the longitudinal axis 48 of the control valve.

The vent 50 is arranged in the cylinder 36 in a position such that the reference chamber 42 has the volume Vi when the O-ring is on the level of the vent 50. The O-ring 58 seals the first piston 30 gas proof with the cylinder 36 and prevents the outflow of gas from the reference chamber 42 to the environment.

When the control valve 28 will be assembled, the first piston 30 will be inserted into the cylinder 36 and moved along the longitudinal axis 48 of the control valve. The reference chamber 42 is gas proof, when the O-ring 58 is above the vent 50.

The rod 34 is arranged on the opposite side of the reference chamber 42 at the first piston 30. The rod 34 links or connects the first piston 30 and the plunger 32. The rod 34 is arranged along the longitudinal axis 48 of the control valve.

The plunger 32 has a front surface, opposite to the rod, at right angles to the longitudinal axis 48 of the control valve, with an area size Av. The plunger 32 has a circular shape seen in direction of the longitudinal axis 48 of the control valve. The front surface of the plunger 32 is arranged in the high-pressure vessel and seals the high pressure vessel. A vessel pressure (pv) in the high-pressure vessel produced a force (Fv) to the plunger 32 in the direction of the longitudinal axis 48 equal the formula:

Fv = Pv^■ A_v The plunger 32 may have a conical shape along the longitudinal axis 48 of the control valve to the rod 34. The plunger 32 seals in an opening 38 of a ring-cylinder 52 which closes the high-pressure vessel 24. The opening 38 also is tapered commensurate to the conical shape of the plunger 32, along the longitudinal axis 48 of the control valve. Through the conical shape the contact area between the plunger 32 and the opening 38 is enlarged. Therefore the sealing of the high pressure vessel 24 can be improved. Since the area size Av of the plunger 32 is larger than in previous embodiments, the force Fv on the plunger 32 is larger, so that a better sealing between the plunger 32 and the opening 38 of the ring cylinder 52 is obtained.

Figure 4 shows a sectional view of the control valve 28 in an open position. The control valve 28 is configured to regulate the gas flow from the high-pressure vessel 24. When the plunger 32 is moved along the longitudinal axis 48 of the control valve towards the high-pressure vessel 24, gas flows out of the high-pressure vessel 24.

The propellant 16 flows then through the control valve 28. The propellant 16 flows through the opening 38 from the high-pressure vessel 24, among the plunger 32 and the ring-cylinder 52 and among the rod 32 and the ring-cylinder 52 into a control valve chamber 54. From the control valve chamber 54, the gas flows through the vent 50 into the container 12. The control valve chamber 54 communicates with the container 12 via the vent 50. Therefore, the pressure in the control valve chamber 54 will be equal to the pressure in the container 12.

The position of the control valve 28 (respectively the first piston 30 and the plunger 32 which are connected by the rod 34) is depending on the pressure in the reference chamber 42 and the control valve chamber 54, the pressure in the reference 42 chamber and the high-pressure vessel 24, respectively.

The pressure pcv in the control valve chamber 54 generated a force Fcv to the first piston 30 in direction of the longitudinal axis 48. The force Fcv is further depending on the area size of the control valve chamber Acv. The area size of control valve chamber is the area size of the first piston 30 minus the area size of the rod 34 which is connected to the first piston 30. Therefore the force Fcv in direction of the longitudinal axis 48 of the control valve is equal to the formula:

Fcv— Pcv ^' Acv

The forces of the reference chamber (FRC) antagonize the forces of the high pressure vessel (Fv) and the forces of the control valve chamber (Fcv). Therefore the position of the control valve 28, that is the position of the first piston 30 and the plunger 32 which are connected by the rod 34, depends on the formula:

FRC - F_v + F_cv For example in Figure 3 the pressure in the container 12 may be 2 bar. Through the vent 50 the container 12 is connected with the control valve chamber 54 and the pressure in the container 12 and the control valve chamber 54 is equal (2 bar). The reference chamber 42 is sealed gas proof towards the control valve chamber 54, therefore the control valve 28 (first piston 30) is moved by the pressure Fcv in the control valve chamber in a position such that the pressure FRC in the reference chamber 42 is also at 2 bar.

The product of the volume and the pressure is constant: V^■ p = const.

As shown in figure 3 the first piston 32 is a position that the opening 38 of the ring cylinder 52 is sealed by the plunger 32 and thus propellant 16 does not flow from the high-pressure vessel 24. When the pressure in the control valve chamber 54 drops, for example since the outlet valve 1 8 is activated and fluid is dispensed from the container 12, the pressure in the container 12 drops also, so that the pressure in the reference chamber PR moves the first piston 30 downwards and thus the plunger 32 is also moved downwards, so that the the control valve 28 in the high- pressure container 24 is opened. Propellant 16 with a higher pressure will flow out of the high-pressure vessel 24 into the control valve chamber 54 and via the vent 50 into the container 12, until the pressure in the container 12 and in the control valve chamber 54 raises to close the control valve 28 again.

Depending on the pressure in the high pressure vessel 24, the plunger 32 will be pressed against the opening 38 of the ring-cylinder 52. The area size Av of the front surface of the plunger 32 may be adapted or adjusted to the area size of the front surface of the plate AR in the reference chamber and the area size of the control valve chamber Acv.

The pressure in the high pressure vessel 24 is for example 8 bar and the pressure in the container is 2 bar. Thus the pressure in the high pressure vessel 24 is four time higher than the pressure in the container 12, therefore on the front surface of the plunger which may be four time smaller affects the same force as on the front surface of the first piston 30. To reduce the influences of the pressure in the high- pressure vessel 24 to the control valve 28, the area size Av of the front surface of the plunger 32 may be reduced compared to the area size AR of the front surface of the first piston 30. For example the area size Av may be 4 to 20 times smaller than the area size AR. Preferably the area size Av may be ten times smaller than the area size AR in the reference chamber 42.

The influences of the pressure pv, in the high-pressure vessel 24 to the front surface Av, and therefore the force Fv which presses the plunger 32 against the opening 38 of the ring cylinder 52, may also be compensated by a higher pressure PR in the reference chamber 42.

Claims

1 . A fluid dispenser (10) comprising:

- a container (12), configured for storing a liquid (14);

- an outlet valve (18) arranged on the container (12), configured to regulate the dispensing of the liquid (14);

- a hollow tube (22) formed from a hydrophilic membrane (60), having a first end (22a) which is linked to the outlet valve (18) so as to be able to communicate with a fluid outlet (20) and a second closed end (22b) within the container (12), wherein

- the hydrophilic membrane (60) is configured to pass liquid in preference to gas so that the liquid (14) flows from the container (12) through the hydrophilic membrane (60) into the hollow tube (22); and

- a high-pressure vessel (24) connected by a passageway (26) to the container (12) and a control valve (28) is arranged in the passageway (26), wherein the control valve (28) is configured to regulate the pressure inside the container (12).

2. The fluid dispenser (10) according to claim 1 , wherein the fluid dispenser (10) comprising a propellant (16).

3. The fluid dispenser (10) according to the claims 1 or 2, wherein the hollow tube (22) is flexible and has a length which is longer than the height of the container (12).

4. The fluid dispenser (10) according to one of the claims 1 to 3, wherein the hydrophilic membrane (60) has a pore size less than 30 nanometres.

5. The fluid dispenser (10) according to one of the claims 1 to 4, wherein the hydrophilic membrane (60) is a capillary membrane.

6. The fluid dispenser (10) according to one of the claims 1 to 5, wherein the container (12) and the high-pressure vessel (24) are substantially cylindrical and share a common longitudinal axis (48).

7. The fluid dispenser (10) according to claim 1 to 6, wherein the control valve (28) is configured to maintain a constant predetermined pressure inside the container (12).

8. The fluid dispenser (10) according to claim 7, wherein a reference pressure chamber (42) is provided comprising a cylinder (36), which is closed by a first piston (30), whereas the control valve (28) comprises an outlet opening (38) of the high-pressure vessel (24) and a plunger (32) closing the opening (38), wherein the first piston (30) is connected by a rod (34) to the plunger (32).

9. The fluid dispenser (10) according to claim 6 and 8, wherein the first piston (30) has a front surface, at right angles to the longitudinal axis (48) of the control valve, with a size AR, and the plunger (32) has a front surface, at right angles to the longitudinal axis (48) of the control valve, with a size Av, and the size of AR is between 4 and 20 times larger than the size of Av.

10. The fluid dispenser (10) according to one of the claims 8 or 9, wherein a ring- cylinder (52) which comprises the opening (38) is arranged at the outlet of the high-pressure vessel (24), whereas the plunger (32) has a conical shape and the opening (38) has a commensurate tapered shape.

1 1 . The fluid dispenser (10) according to one of the claims 8 to 10, wherein a second piston (46) is movable arranged in the container (12) and is configured to separate the container (12) in a first chamber (12a) and in a second chamber (12b), wherein the high-pressure vessel (24) is connected over the control valve (28) with the second chamber (12b).

The fluid dispenser (10) according to one of the claims 8 to 1 1 , wherein the second piston (46) is configured to separate the first chamber (12a) and in the second chamber (12b) in a gas tight manner.