Abstract:
Metering Powdery or Flaky or Fine-Grained Dosing Material, such as Coffee Powder, Milk Powder or Cocoa Powder by use of a metering device having a container for accommodating the dosing material, and a metering chamber for metering one portion of the dosing material arranged at the outlet of the container. The dosing material is discharged into a collecting receptacle via a discharge port each time an actuating element is actuated. The dosing material is acted upon by an air current generated by a blower during its metered discharge.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of PCT application serial number PCT/EP2004/011841, filed Oct. 20, 2004, which claims priority under 35 U.S.C. §119(a) from German application serial number DE 103 54 003.2, filed Nov. 19, 2003, the entire contents of both of which are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     This disclosure relates to metering powdery or flaky or fine-grained dosing material, such as coffee powder, milk powder, or cocoa powder.  
       BACKGROUND  
       [0003]     Patent No. DE 38 10 143 C1, discloses a coffee machine with a metering device. The metering device has an actuating element in the form of a screw conveyor that is positioned at the outlet of a container filled with dosing material. The revolutions of the screw conveyor determine whether more or less dosing material is discharged at a discharge port into a funnel situated under the discharge port. In this metering device, the funnel is located in direct contact with the brewing chamber. When the coffee machine is used several times in succession, hot steam originating from the brewing chamber can rise and moisten the discharge port of the metering device during the time period when the funnel is opened toward the brewing chamber to introduce the dosing material.  
         [0004]     After a period of time, this process can lead to an accumulation of moisture on the discharge port. As a result, the dosing material being discharged adheres to this moisture on the dischagre port. As the quantity of dosing material accumulating on discharge port increases over time, the discharge port becomes increasingly constricted. Ultimately, this can result in the discharge port becoming completely clogged, which results in the complete failure of the metering device.  
         [0005]     Additionally, the dosing material adhering to the discharge port is constantly moistened by the rising steam. This can result in the dosing material caking and even turning moldy or growing harmful bacteria after extended use. This may lead to the metering device rendering the coffee inconsumable.  
       SUMMARY  
       [0006]     In one aspect of the invention, a blower positioned on a metering device generates an air current that acts upon, and transports the dosing material discharged into a collecting receptacle. In some implementations, the collecting receptacle can be an intermediate container that lies adjacent to a brewing chamber for brewing a beverage. In other implementations the collecting receptacle can be the actual brewing chamber, in which the dosing material is brewed, of a machine for preparing beverages.  
         [0007]     The air current being generated now makes it possible to position the collecting receptacle or brewing chamber so far from the metering device that rising steam originating from the brewing chamber is no longer able to reach the metering device. If the brewing chamber still needs to be arranged directly underneath the metering device, the air current prevents the rising steam from reaching the metering device. Preferably, the outlet remains dry and no powder is able to adhere to the outlet. This can prevent the metering device from clogging, and the dosing material from being contaminated, for example, by mold or bacteria.  
         [0008]     In some embodiments, the air current is directed in the same direction as the direction that the dosing material is discharged, i.e., away from the discharge port. However, the air current may also be directed transverse to the direction in which the dosing material is discharged. As a result, the dosing material is deflected and subsequently delivered into the collecting receptacle in an equally directional fashion.  
         [0009]     The intensity of the air current can be maintained in a relatively low range due to the directed transport in the defined channel. This can be achieved with a channel that surrounds the discharge port, and into which the air current is introduced at the discharge port. The air current may be directed essentially parallel to the channel, but may also be introduced into the channel transverse to, and in the longitudinal direction thereof via several jets in order to generate turbulences. Thus, ensuring that the entire dosing material can be acted upon and transported to the collecting receptacle.  
         [0010]     In some embodiments, individual jet pipes are provided that lead into the channel radially outside the discharge port, and extend in the direction of the channel outlet in the interior of the channel, i.e., essentially parallel thereto. In other embodiments the inlet of the channel can have a cross section in the form of the ring channel that is arranged outside of, and surrounds the wall of the discharge port. In this embodiment, the coherent air current being annularly introduced into the channel is directed either parallel to the channel or slightly inward toward the center of the channel such that it can act upon and transport the entire dosing material to the channel outlet.  
         [0011]     In some cases, an exactly metered quantity of the dosing material is discharged per piston stroke at the discharge port. This means that a certain metered quantity of powder can be discharged with each piston stroke. The small metered quantity discharged per stroke makes it possible to adjust the strength of a brewed beverage because one to three piston strokes can be carried out in order to brew a weaker beverage, while four to seven piston strokes can be carried out in order to brew a stronger beverage from the four to seven small quantities of the dosing material that are discharged. The size of the metering chamber can be chosen such that the metered quantity per piston stroke amounts to approximately 0.1 g, i.e., if approximately 2 g are required for preparing one cup of medium-strength instant coffee, the piston needs to carry out twenty strokes within a short period of time. During the proposed movement achieved by means of magnetic forces, the piston forms the magnet core and the coil forms the magnetic field for moving the piston into the coil. This can take place within such short intervals that only a few seconds are required for twenty strokes. If the coil is designed for moving the piston in one direction only, a spring needs to be provided in order to ensure that the piston is always returned into its initial position. However, the coil and the piston may also be adapted to one another in such a way that the coil moves the piston in one direction as well as in the opposite direction.  
         [0012]     The air current can be generated by an electrically driven fan wheel, wherein the fan wheel may consist of a radial-flow as well as an axial-flow wheel. In order to make it possible to utilize a fan wheel with particularly small dimensions, the electric motor needs to have a relatively high speed, for example, of 8.000 to 20.000 rpm.  
         [0013]     The collecting receptacle can either form the brewing chamber or a funnel that is directed toward the brewing chamber. Due to the generation of an air current in a machine, which is used for preparing beverages and which is suitable for household use, the brewing chamber can be arranged directly underneath the discharge port, if the air current prevents the steam originating from the brewing chamber from reaching the discharge port. However, in some embodiments, brewing chamber can be positioned laterally adjacent to the discharge port or even above the discharge port, in which case it is necessary to provide a channel for delivering the dosing material to the brewing chamber.  
         [0014]     Other aspects, features, and advantages will be apparent from the following detailed description, the drawings and the claims. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  shows a metering device with a piston in a position where the outlet of the metering chamber is open, such that the dosing material is able to drop into the metering chamber, i.e., the actuated state of the metering device, and  
         [0016]      FIG. 2  shows the metering device, according to  FIG. 1 , after the piston has closed the outlet of the metering chamber and discharged the dosing material from the discharge port, i.e., the initial state of the metering device. 
     
    
     DETAILED DESCRIPTION  
       [0017]      FIGS. 1 and 2  show schematic or basic representations of a metering device  1 , such as a beverage dispenser. The metering device  1  consists of a funnel-shaped container  2  that is open on its upper end and can be closed with a cover  40  ( FIG. 2 ). The container serves as a reservoir for powdery, or flaky, or fine-grained dosing material  3 . The container  2  can be downwardly tapered, as shown in the figures. An outlet  4  arranged at the narrowest point of the container  2  lies directly above a bore  5  that extends perpendicular to the outlet  4 . The bore  5  can have a circular cross section. The bore  5  is arranged in a housing  6 , into which the container  2  is also integrated. A reciprocating piston  7  is located in the bore  5  and is also located in another bore  8  of a coil body  10 . The coil body  10  is located in another housing  9 . The right end  14  of the reciprocating piston  7  can be positioned as shown in the figures. The bores  5  and  8  are aligned with one another such that a smooth movement of the piston  7  is ensured.  
         [0018]     The housing  9 , the coil body  10 , and the piston  7  form the actuating element  11  of the metering device  1 . The actuating element  11  and the metering device are stationarily mounted, for example, in a machine for preparing beverages that is not illustrated in the figures. The coil body  10  consists of a copper wire  42  of superior current conductivity that is embedded in a toroidal chamber  12  and, when conducting a current, generates a magnetic field, such that the piston  7  is drawn into the bore  8 . The connection to a current is not illustrated in the figures.  
         [0019]     A helical pressure spring  15  is situated in the bore  8  of the actuating element  11  between the bottom  13  of the housing  9  and the free end  14  of the piston  7 , as shown in the figures. The pressure spring displaces the piston  7  into the bore  5  of the housing  6  of the metering device  1  when the actuating element  11  is not actuated. The helical pressure spring  15  displaces the piston  7  to such a degree that the piston completely closes the outlet  4  ( FIG. 2 ) and extends beyond the outlet as far as the discharge port  18  inside the bore  5 . Thus, the valve arrangement  16  is realized in the form of a slideable valve.  
         [0020]     An annular extension  17  of the bore  5  is situated adjacent to the housing  6  of the metering device  1 . The annular extension  17  is on the left side of bore  5  and in the direction of motion of the piston  7  shown in  FIG. 2 , wherein a discharge port  18  is formed on the free end of this annular extension. A tube section  19  can be integrated into the housing  6  or formed in one piece therewith. The tube section  19  extends concentrically around the annular extension  17  and extends further toward the left beyond the extension  17 . An annular chamber  20  is formed by the area between the tube section  19  and the extension  17  because the outside diameter of the extension  17  is smaller than the inside diameter of the tube section  19 . The annular chamber  20  is connected to the fan wheel  44  of a blower  22  that is only schematically indicated in the figures via a flow channel  21 . The blower  22  can also be connected by a hose (not shown) to the end of the flow channel  21  that is realized in the form of a pipe socket  23 , such that the blower  22  can also be positioned in the device independently of, and at a greater distance from, the metering device  1 .  
         [0021]     The tube section  19  essentially extends parallel to the piston  7  and to the bore  5 . The edge  24  of the tube section  19  defines the outlet  43  for the metered dosing material  25  that is illustrated in the idealized form of a pellet. The sides  26  of the dosing material  25  actually do not form straight surfaces that extend perpendicular to one another.  
         [0022]      FIG. 1  schematically shows a brewing chamber  27 , into which the dosing material  25  drops in order to be mixed with hot water and brewed. A baffle  28  is provided on the left side of the brewing chamber  27  in order to improve the dropping of the dosing material  25  into the brewing chamber. The top of the brewing chamber  27  is open, and the edge  29  of the filling opening  30  is offset toward the bottom left with reference to the free end  24 . Naturally, the brewing chamber  27  illustrated in  FIG. 1  is also provided in  FIG. 2 , in which it was omitted in order to prevent unnecessary repetitions.  
         [0023]     The metering device  1  according to the invention functions as described below:  
         [0024]     The initial position of the metering device  1  is illustrated in  FIG. 2 . In the initial position, the piston  7  blocks the outlet  4 , such that no dosing material  3  can flow into the metering chamber  31 . It should also be noted that the metering chamber  31  extends beyond the region of the bore  5 , over which the outlet  4  extends along the bore  5 . In the initial position of the metering device  1 , the left end  32  of the piston, as show in  FIG. 2 , is flush with the face  33  of the extension  17 , ensuring that the dosing material  25  is discharged in its entirety into the tubular chamber  34  of the tube section  19 . The pressure spring  15  defines the closed position of the metering device  1 , as shown in  FIG. 2 , because it is mounted on the bottom  13  of the housing  9  as well as on the free end  14  of the piston  7  and therefore holds the piston  7  in the position shown in its relaxed state.  
         [0025]     When a brewing process is initiated, dosing material  3  needs to be transported from the container  2  into the brewing chamber  27 . This is achieved by supplying the coil body  10  with a current, such that a magnetic field is generated that draws the piston  7  into the bore  8 . As shown in  FIG. 1 , piston  7  moves toward the right as indicated by the arrow  35  against the force of the spring  15 . During this process, the outlet  4  is opened and dosing material  3  is able to drop into the metering chamber  31  until it is completely filled. The blower  22  was already switched on shortly before this time and generates the air current  39  which is directed into the annular chamber  20  via the flow channel  21 . The air current flows to the free end  24  of the tube section  19  as indicated with the arrows  36 , and then outward. The current supply of the coil body  10  is simultaneously shut off, such that the magnetic field abruptly drops, and the force of the spring  15  causes the piston  7  to move in the direction of the arrow  37 , as shown in  FIG. 2 . The front end  32  of the piston displaces the metered dosing material  25  out of the metering chamber  31  along the bore  5  until the dosing material  25  is discharged from the bore and introduced into the channel  38  formed by tube section  19 . At this location, the air current  36  starts to act upon the dosing material  25  such that it is accelerated and transported in the direction of the baffle  28 , where the dosing material  25  is deflected downward and introduced into the brewing chamber  27 .  
         [0026]     The air current  39  at the inlet that is indicated with an arrow can also be pre-heated by means of a not-shown heating device in order to maintain the entire metering device  1  warm and dry and, if applicable, to simultaneously dry slightly moist dosing material  25 . Due to these measures, dosing material  25  cannot be deposited on the extension  17  and/or on the tube section  19 , and thus cannot clog the metering device  1 . The piston  7  is moved back and forth in accordance with the desired number of cups of the respective beverage to be brewed. Piston  7  discharges a predetermined quantity of dosing material  25  that corresponds to the volume of the metering chamber  31  with each piston stroke. Once the brewing process is concluded, the blower  22  can be switched off immediately or after a certain follow-up time that also serves for cleaning and drying the metering device  1 .  
         [0027]     The housing  6  as well as the container  2  and the tube section  19  can be fabricated in the form of a single injection-moulded plastic part. The piston  7  can also be made of plastic in order to keep the moving masses low.  
         [0028]     The brewing chamber  27  that is indicated in  FIG. 1  may form part of the mixing device for mixing a powdery, soluble extract as described in patent application PCT/EP03/12026, the contents of which are hereby incorporated by reference as part of this application.