TECHNICAL FIELD

The present invention relates to reciprocating pumps for dispensing a liquid. More particularly, the invention relates to a reciprocating pump assembly comprising a pump housing providing an interior compartment. The pump housing is provided with an inlet for providing a liquid to be dispensed and an outlet for dispensing the liquid. The assembly further comprises a piston movably mounted within the interior compartment of the pump housing. The piston comprises ferromagnetic material. The assembly further comprises a magnetic actuator for generating a linearly moving magnetic field acting on the piston.

BACKGROUND

In beverage dispensers using pouches or the like for providing liquid concentrate, the dispensing of the concentrate liquid is done by a pump. Typically, the pump is part of the dispenser and a concentrate liquid bag or pouch is connected to the pump on one side and the mixing water on the other side. In order to ensure a high quality beverage dispenser it is essential to clean and sanitize especially the concentrate liquid dispensing system periodically to avoid the growth of bacteria which might be harmful to the customers and degrade the quality of the dispensed beverage. Therefore, the pumps are often designed to be disposable or recyclable. US2006/0151544 discloses a disposable concentrate pump where a small pump body is part of a liquid collapsible bag reservoir, and an actuating solenoid is mounted in the dispenser. When a new bag is loaded, the attached pump body is inserted into a solenoid. When the bag is empty parts of the pump will be disposed, along with the empty bag. The pump is connected to streaming water and is arranged in an electrical appliance. GB 2103296 discloses a pump having a pumping chamber defined by a flexible or resilient cylindrical chamber wall, and non-return inlet and outlet valves. Pumping is effected by aerial deformation of the pumping chamber achieved by electro- magnetic actuating means. The liquid to be dispensed is stored in a collapsible container.

EP1018601 discloses a reciprocating pump. A piston assembly has a dispensing end and an opposed end and is moveably mounted for reciprocating movement in opposed linear directions. A linear magnetic drive generates a linearly moving magnetic field for moving the piston assembly in opposed linear directions through a swept volume in each of the opposed linear directions. An energy storage and release media communicates with a reservoir chamber for storing energy as a result of movement of the piston assembly in a direction away from the dispensing end of the interior compartment and for releasing the stored energy as the piston assembly is moved in a direction toward the dispensing end of the interior compartment. The pumped flow rate is high and a powerful drive is therefore needed. All pump devices mentioned above are detachable from their actuating

mechanisms and are therefore easily replaceable. The known reciprocating pumping mechanisms are all driven by an electromagnetic actuating mechanism. Such type of driving requires a power source such as a battery or connection to the power net to enable the magnet to generate a proper magnetic field.

Electromagnetic driving mechanisms of this type are complex and expensive, and occupy a lot of space. Further, for small, not water mains connected and/or non- powered appliances such as water pitchers or table top water carbonators, a driving mechanism without the need for a separate power source is preferred. Thus, there is a need for a pump with an improved actuating mechanism. SUMMARY

An object of the present invention is to provide a reciprocating pump overcoming at least some of the drawbacks mentioned above.

According to a first aspect of the invention, this object is achieved by a

reciprocating pump assembly for dispensing liquids, the pump assembly

comprising: a pump housing providing an interior compartment, the pump housing being provided with an inlet through which a liquid to be dispensed is provided, and an outlet for dispensing the liquid. The assembly further comprises a piston being arranged to perform a linear movement within the interior compartment of the pump housing. The piston comprises ferromagnetic material. The assembly further comprises a magnetic actuator for generating a linearly moving magnetic field acting on the piston. The magnetic actuator comprises a permanent magnet arranged to be moved linearly substantially parallel to the linear movement of the piston, whereby the linearly moving magnetic field is generated, and the piston is moved in the pump housing between a resting position and an actuated position under influence of the generated linearly moving magnetic field.

The present invention provides a reciprocating pump assembly with a robust and simple actuating mechanism with low risk for parts malfunctioning. Further, a compact and robust assembly that will fit into small and cheap applications is provided. Due to the use of a permanent magnet, there is no need for any external power supply. The robust and simple construction limits the risk for malfunctioning. Due to the use of magnetic forces in the actuator, there are no mechanical connection between the actuator and the piston, and any individual part of the assembly may therefore be replaced easily. As a result, the above mentioned object is achieved. In another embodiment, the reciprocating pump assembly further comprises a first biasing member arranged to apply a force on the permanent magnet whereby the permanent magnet is retracted from the actuated position to the resting position. By combining a permanent magnet with a spring, a firmer, quicker and more accurate movement of the generated magnetic field, and thereby of the piston, is obtained. Further, the reciprocating pump assembly may comprise a second biasing member arranged to apply a force on the piston whereby the piston is retracted from the actuated position to the resting position. The second biasing member provides a faster return of the piston, thereby still further improving the movements of the piston.

In yet another embodiment are the permanent magnet and the second biasing member arranged to interact whereby the permanent magnet is moved in opposed linear directions in relation to the movements of the piston. The forces from respective biasing member will then be used to fully contribute to achieve quick and fast movements of the piston.

In another embodiment is the force applied by the second biasing member on the piston overcoming the magnetic force acting on the piston, when the piston is positioned in the resting position. Thereby, the piston will be safely positioned in the resting position when the pump is not in use. Further, the risk of unwanted leakage is limited.

In yet another embodiment overcomes the magnetic force acting on the piston the force applied by the second biasing member on the piston, when the permanent magnet starts to move from the resting position in a linear direction towards the piston. The movement of the piston will therefore start shortly after movements of the permanent magnet resulting in a quick and fast movement of the piston. In yet another embodiment, the assembly comprises a check-valve, whereby liquid is enabled to flow into the interior compartment, and whereby liquid is blocked from flowing back. The liquid provided will thus be fresh and uncontaminated. In a preferred embodiment is the outlet of the pump housing provided with a nozzle.

In a preferred embodiment are the movements of the permanent magnet achieved by movements by hand of a user.

To achieve a magnetic field strong enough to move the piston in a satisfying manner, a permanent magnet made from Neodymium (NdFeB) or equivalent may be chosen. In another aspect of the invention, a household appliance comprising such a reciprocating pump assembly is provided. Since there is no need for such pump assembly to be connected to a power net, such a solution will provide easy assembling and construction of the appliance, as well as reliable functionality. Further, small appliances like water pitchers or table top carbonators may be used without any external power source or net.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed

description. Those skilled in the art will realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention, as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which: Fig. 1 illustrates a reciprocating pump in accordance with prior art.

Fig. 2 illustrates a reciprocating pump in accordance with the present invention.

Fig. 3 illustrates a reciprocating pump in accordance with the present invention shown in a resting position.

Fig. 4 illustrates a reciprocating pump in accordance with the present invention shown in an actuated position. DETAILED DESCRIPTION

The present invention will now be described more fully with reference to the accompanying drawings, in which example embodiments are shown. However, this invention should not be construed as limited to the embodiments set forth herein. Disclosed features of example embodiments may be combined as readily understood by one of ordinary skill in the art to which this invention belongs. Like numbers refer to like elements throughout.

Fig. 1 shows a pump system in accordance with prior art. A pump 15 is connected to a pouch 1 1 or the like comprising a liquid to be dispensed. To perform a positive displacement of a liquid from a pouch 1 1 to the outside, the pump 15 performs a reciprocating movement. An electro magnet 14 is arranged to generate a moving magnetic field acting on the pump 15, whereby the magnetic force from the field causes the pump 15 to move in the same manner. By the reciprocating movement performed by the pump 15, a positive displacement of liquid from the pouch 1 1 to the outside is obtained. The electro magnet 14 is controlled by a Printed Circuit Board (PCB) 12 connected to an external power source 13, like a battery package or a power net. Electronic circuits on the PCB 12 controls the voltage applied on the electro magnet 14 in such a way that a moving magnetic field is generated. Fig. 2 illustrates an embodiment of a reciprocating pump assembly 1 in accordance with the present invention. The pump assembly 1 may be connected to a pouch 1 1 comprising a consumable liquid to be dispensed. The pump assembly 1 comprises a piston 5 made of ferromagnetic material arranged inside a pump housing 2. To perform a positive displacement of a liquid from a pouch 1 1 to the outside, the piston 5 performs a reciprocating movement. A permanent magnet 6 is arranged on the outside of the pump housing 2. The permanent magnet 6 is moved in a reciprocating manner whereby the magnetic force from the magnet 6 causes the piston 5 to move in a reciprocating manner. By the reciprocating movement performed by the piston 5, a positive displacement of liquid from the pouch 1 1 to the outside is obtained.

Fig. 3 illustrates a further embodiment of a reciprocating pump assembly 1 in accordance with the present invention. The pump assembly 1 may further comprise first and second biasing means 7, 8, in the figure shown as springs, but may be any type of biasing member. The springs are acting on the piston 5 and on the permanent magnet 6, respectively. The permanent magnet 6 is moved in a counter direction in relation to the piston 5 whereby the forces of the biasing members 7, 8 are utilized to achieve a faster reciprocating movement, obtaining a higher velocity of the out flowing liquid and a higher pressure at the nozzle 10. By combining a permanent magnet 6 with a first biasing member 7, a firmer and quicker movement with higher accuracy of the permanent magnet and thereby of the magnetic field acting on the piston 5 is obtained. Providing also the piston with a second biasing member 8 will further improve the movements of the piston 5. The second biasing member 8 may advantageously be dimensioned to achieve that the magnetic force acting on the piston 5 overcomes the force applied by the second biasing member 8 on the piston when the permanent magnet 6 starts to move from the resting position in a linear direction towards the piston. The movement of the piston 5 will therefore start shortly after movements of the permanent magnet resulting in a quick and fast movement of the piston. The biasing member 7 may be dimensioned to apply a force strong enough to ensure that the magnet 6 is kept from moving towards the piston 5 when the assembly is in the resting position as shown in Fig. 3.

A check valve 9 may be comprised, allowing the liquid to flow only in one direction, from the pouch 1 1 to a pump nozzle 10 through which the liquid is dispensed.

When in use, the pump assembly 1 works as follows. When the pump is in a resting 10 position as shown in Fig. 3, the force from the spring 8 acting on the piston 5 is stronger than the force generated by the magnetic field of the

permanent magnet 6 acting on the piston 5. Thereby, the piston 8 is kept in the resting position. A user pushes the permanent magnet 6 from its resting position towards the force of the spring 7 whereby the spring is contracted. When the permanent magnet 6 is moved close enough to attract the piston 5 and to overcome the force of the spring 8, the piston 5 is moved from its resting position towards the permanent magnet 6 and the spring 8 is thereby contracted. Thereafter, the user let go of the permanent magnet 6 and the magnet is retracted to the resting position by the force of the spring 7. When the permanent magnet 6 is moved away from the piston 5, the force from the spring 8 overcomes the force of the magnet 6 and the piston 5 is moved back to its resting position by the force of the spring 8. The piston 5 and the permanent magnet 6 are shown in their actuated positions, with respective spring contracted, in Fig. 4. To achieve a magnetic field strong enough to move the piston 5 in a satisfying manner, a permanent magnet made from Neodymium (NdFeB) or equivalent may be chosen.

Example embodiments described above may be combined as understood by a person skilled in the art. Although the invention has been described with reference to example embodiments, many different alterations, modifications and the like will become apparent for those skilled in the art.

Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and the invention is not to be limited to the specific embodiments disclosed and that modifications to the disclosed embodiments, combinations of features of disclosed embodiments as well as other embodiments are intended to be included within the scope of the appended claims.

The terminology used herein is for the purpose of describing particular

embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Example embodiments of the present invention have been described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments, and intermediate structures, of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances are to be expected. Thus, embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shape that result, for example, from manufacturing.