Abstract:
Systems and methods for brewing beverages in accordance with the present invention can improve the flavor of brewed beverages and reduce the vertical space required for a system using suction. One such assembly comprises a brewing chamber adapted to hold a filter having an intake duct for receiving fluid for brewing, and an output duct for expelling a brewed beverage. The brewing chamber is positioned above a pressurizable container, or carafe, having an adjustable standpipe and containing the fluid. The carafe has a heated base, which when heated causes pressure to build up, forcing the fluid up the standpipe, through a check valve, through the intake duct and into the filter. Once substantially all of the fluid has been urged into the brew chamber, the heat is removed, creating a partial vacuum that pulls the brewed beverage back into the carafe. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Description:
[0001]    This application claims priority to U.S. Provisional Application No. 60/370,142 entitled “VACUUM COFFEE MACHINE,” by Robert C. Hall, Gary L. Waymire, Michael R. Barry, and Shane Washburn, filed Apr. 5, 2002, and to U.S. Provisional Application No. 60/369,275 entitled “VACUUM COFFEE MACHINE,” by Robert Hall, filed Apr. 2, 2002, which are hereby incorporated herein by reference. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates to systems that rely on suction for brewing beverages; for example, vacuum coffee makers.  
         BACKGROUND  
         [0003]    Beverages such as tea and coffee which rely on steeping and/or brewing to extract flavor from leaves or grounds are popular and prevalent. There are many different systems and many techniques for brewing, producing varying results in texture and flavor. Many of these systems (for example vacuum coffee makers) rely on suction in the brewing process.  
           [0004]    In a vacuum coffee maker there are typically two containers, one above the other, with a tube extending down from the bottom of the upper container to the lower container. A filter is placed at the top of the tube and dry coffee grounds are placed on the filter. The lower container is filled with water and the two containers are fitted together such that a seal is formed.  
           [0005]    A heating element, either integrally formed with the lower container or placed beneath the lower container, heats the water in the lower container. As the water boils and expands, water and water vapor (steam) are forced up the tube, past the filter, and into the upper container, mixing with the coffee grounds. When the water in the lower container has nearly completely evaporated, the heating element shuts off or current to the heating element is reduced, causing the temperature in the lower container to cool and the pressure to drop, creating suction and drawing water through the filter and into the lower container. The upper container is removed and the coffee is served from the lower container.  
           [0006]    There are advantages to brewing systems that rely on suction. Coffee brewed using a vacuum coffee machine is often considered full-bodied without heavy sediment. Water can be poured into a lower container rather than into the upper container. But there are disadvantages as well. For example, the flow of the water up the tube, especially when only a small quantity of water remains in the lower container, can become erratic due to formation of steam bubbles from the heater surface. This leads to intermittent pressurized flow of water upwards through the tube, especially towards the end of the heating cycle. Also, the vacuum coffee machine cannot be used in a compact vertical space. To remove the lower container for serving, the vacuum coffee machine must be disassembled. In order to remove the lower container, the tube must be separated from the lower container. To separate the tube from the lower container, the seal between the upper and lower chambers must be broken and the upper chamber vertically separated from the filter and tube. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0007]    Further details of embodiments of the present invention are explained with the help of the attached drawings in which:  
         [0008]    [0008]FIG. 1 is a perspective view of an embodiment of the present invention;  
         [0009]    [0009]FIG. 2 is a perspective view of the invention shown in FIG. 1 illustrating separation of a carafe and a brew chamber;  
         [0010]    [0010]FIG. 3 is a perspective view of the carafe shown in FIG. 2;  
         [0011]    [0011]FIG. 4 is a partial assembly view of the invention shown in FIG. 1 illustrating several components of the brew chamber; and  
         [0012]    [0012]FIG. 5 is a cut-away view of the invention shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0013]    FIGS.  1 - 5  illustrate one embodiment of a system for brewing beverages in accordance with the present invention. As shown in FIG. 1, when assembled for brewing, coffee machine  10  comprises two chambers disposed one atop the other: a lower chamber (or carafe)  12 , and an upper chamber (or brew chamber)  14 . The carafe  12  and the brew chamber  14  operate together to heat the water and brew the coffee.  
         [0014]    The carafe  12  is a vessel for both heating water and storing brewed coffee. The carafe  12  has a storage area defined by a substantially cylindrical side wall  18 , a top  20 , and a bottom surface  22 . In other embodiments, the carafe  12  can be substantially spherical in shape. In still other embodiments, the carafe  12  can be tear-drop shaped. One of ordinary skill in the art can appreciate the different shapes with which the carafe  12  can be formed. The side wall  18  can be made of single-wall glass or stainless steel, evacuated double-wall glass or stainless steel, high density polyethylene, or a material having similar insulating properties. The top of the carafe  20  includes a pour spout  30 , and a brew strength adjuster  28  having an opening  26 . Extending outward from the top  20  is a handle  24 , allowing a user to transport the carafe  12  without touching the wall  18  or base  42  when the carafe  12  contains hot coffee.  
         [0015]    Located inside the carafe  12  is a standpipe  32 . The standpipe  32  is mounted to a threaded fitting in the brew strength adjuster  28  of the carafe  12 . Twisting the brew strength adjuster  28  in a first direction raises the standpipe  32  slightly within the carafe  12 . Twisting the brew strength adjuster  28  in a direction opposite the first direction lowers the standpipe  32  slightly within the carafe  12 . The standpipe  32  is a tube having a top end  34  and a lower end  36 . The standpipe  32  can be circular in cross-section, or alternatively can be elliptical or polygonal in cross-section. The standpipe  32  provides a path for the heated water and steam to travel up towards the brew chamber  14 , and a path for the brewed coffee to travel down into the carafe  12 .  
         [0016]    A vent hole  40  is located on the standpipe  32 , above a fill line (not shown) and below the top of the carafe  20 . The vent hole  40  relieves air pressure buildup that results from the heating of the water that, in turn, heats the air above the water. The heating of the air in a fixed volume causes the air pressure to rise within the carafe  12 . The vent hole  40  allows any pressurized headspace gasses (mostly air, prior to boiling) to escape to the atmosphere by escaping up the standpipe  32 , around the brew chamber  14 , and into the grounds.  
         [0017]    In a typical vacuum coffee machine a slight pressure rise will cause some insufficiently heated water in the carafe  12  to be forced up the standpipe  32  and into the grounds. This “flooding” of the grounds with sub-temperature water prevents accurate timing of the full-immersion brewing step (see below). It also reduces the time-averaged temperature of the water in contact with the grounds. This causes poor taste quality of the coffee.  
         [0018]    The carafe  12  has sealing surfaces proximate to the opening  26  of the brew strength adjuster  28  and the pour spout  30 . As shown in FIGS. 5 and 7, the brew strength adjuster  28  forms a seal with o-rings  29  located at the bottom of the brew chamber  14  when the carafe  12  is fully inserted into the housing  16 . The pour spout  30  forms a proximity seal, with a surface  31  of the brew chamber  14  substantially parallel to the slope of the pour spout  30 . In other embodiments, the spout  30  has an end cap or retractable cover or similar sealant means. The only path connecting the interior of the carafe  12  to the brew chamber  14  is through the standpipe  32 .  
         [0019]    The base  42  of the carafe  12  also contains an integral heater  44 . The heater  44  electrically heats and boils the water within the carafe  12 , and keeps the brewed coffee warm when it returns to the carafe  12 . An electrical connection is made for the heater  44  when the carafe  12  is slid into the main housing  16 . A “docking” type electrical connector  46  is used similar to those used on cordless clothes irons. In other embodiments, the carafe  12  can be plugged into an electrical outlet using a cord. In still other embodiments, the heater  44  can be powered by a battery, allowing for portability. One of ordinary skill in the art can appreciate the different methods for powering the heater.  
         [0020]    The base  42  of the carafe  12  maybe detached from the body of the carafe  12 . This allows economical replacement of a damaged body without having to also replace the base  42 . For example, if the glass wall  18  breaks, the base  42  can be removed from the carafe  12 . A user can buy a new carafe  12  without a base  42  and connect the original base  42  to the new carafe  12 .  
         [0021]    All flow into the carafe  12  and out of the carafe  12  during the brewing process must travel through the standpipe  32 . The brew chamber  14  splits the standpipe flow-path into two parts: a “fill and brew” path and an “aspiration” (or output) path. The “fill and brew” path travels around and above the filter  48  to direct boiled water and steam into the grounds within the filter  48 . The “aspiration” path extends from just below the filter  48  in the bottom of the brew chamber  14  to the standpipe  32 . Each flow-path contains a check valve to cause the proper direction of the flows in sequence depending on whether the pressure is positive or negative (partial vacuum) within the carafe  12 .  
         [0022]    The “fill and brew” path comprises a first flow tube  50 , a flexible connector  52 , and a second flow tube  54 . The first flow tube  50  includes a check valve  56  located at the end of the first flow tube  50 . The check valve  56  in the “fill and brew” path is oriented to allow boiled water and steam to move from the carafe  12 , up the standpipe  32 , around the filter  48 , and down into the pile of grounds. As shown in FIG. 5, the check valve  56  can be a ball  58  within a cavity  59  having an opening  61   a  and  61   b  on each end. The diameter of each opening  61   a  and  61   b  is smaller than the diameter of the ball  58 , allowing the ball  58  to travel only within the cavity  59 . The check valve&#39;s orientation prevents aspiration of filter contents when a partial vacuum is formed in the carafe  12  by the cessation of boiling. In most systems, the check valve  56  has a forward pressure drop of less than two inches of water at the flow rates produced by the boiling in the carafe  12 .  
         [0023]    The reverse flow resistance created by the check valve  56  prevents the filter&#39;s interior contents from being aspirated into the carafe  12  during the “suck-back” phase of the brewing cycle, thereby preventing grounds and sediments from being drawn into the carafe  12 . To accomplish this, the ball  58  forms a seal with the opening  61   a  when the ball  58  is at its lowermost position (see FIG. 5). This seal prevents water or steam containing coffee grounds from traveling back into the carafe  12 . The check valve  56  also has a minimum hysteresis in order to produce a steady flow of steam into the grounds/water mixture in the brew chamber  14 , preventing messy surges or bursts.  
         [0024]    The check valve  60  in the “aspiration” (or output) path is oriented to allow filtered coffee from the brew chamber  14  to be sucked down into the carafe  12  by the partial vacuum formed when the boiling is stopped. When a partial vacuum develops in the carafe  12 , the check valve  60  opens and allows a high flow rate of the finished coffee into the carafe  12  through the standpipe. The check valve&#39;s orientation prevents boiled water or steam from moving up the carafe  12  toward the bottom of the filter  48  during the brew chamber filling process. Boiled water or steam moving in this direction does not mix properly with coffee grounds and can upset or deform the filter  48 , spilling the contents such that the carafe  12  is contaminated. In most systems, the maximum back-pressure on the valve  60  is less than ten inches of water.  
         [0025]    The check valves  56  and  60  can be standard, one-way valves that offer low resistance to flow in one direction and block reverse flow. Such valves only allow fluids to move one direction through a pipe or duct. Check valves are common, simple, low-cost, and available in many different styles, sizes, and materials. For example, in other embodiments, the first flow tube  50  can include a tilt-disc check valve. In still other embodiments, the first flow tube  50  can include a flapper valve.  
         [0026]    When the water in the carafe  12  reaches a full boil, the volume of steam created by the full boiling “overwhelms” the standpipe vent hole  40 ; that is, the vent hole  40  can no longer prevent the pressure from rising in the headspace of the carafe  12 . Hot water from the carafe  12  is forced up the standpipe  32 , through the first and second flow tubes  50  and  54  and down through the nozzle  62  into the midst of the coffee grounds in the filter  48 . As the boiling water level in the carafe  12  drops below the lower end  36  of the standpipe  32 , a high volume of steam begins escaping up through the now-open bottom end  36  of the standpipe  32 , through the path-way around the filter, and is released by the nozzle  62  into the mixture of boiled water and grounds. The steam bubbles up through the mixture, keeping the mixture from cooling and agitating the mixture for an ideal full-immersion brew.  
         [0027]    This “steam powered” heating and mixing process continues until substantially no more water is left in the carafe  12 . The length of time for this mixing process depends on the volume of water left in the carafe  12  at the time of the “unporting” of the lower end  36  of the standpipe  32 . By twisting the brew strength adjuster  28  and adjusting the height of the lower end  36  of the standpipe  32  above the bottom of the carafe  12  (i.e. the heater  44 ), the mixing time can be adjusted.  
         [0028]    Typically the upper brew chamber contains the standpipe. When the brew chamber is mated to the top of the boiling chamber/carafe, the standpipe must be inserted down into the neck of the carafe. This requires the vertical separation of the brew chamber from the carafe by an amount equal to the length of the protruding standpipe. A minimum of vertical movement of the brew chamber is required because of consumer space requirements. By making the standpipe  32  part of the carafe  12 , no part of the brew chamber  14  protrudes into the carafe  12 . Only a few millimeters of vertical motion by the brew chamber  14  relative to the carafe  12  is needed for seal operation. For seal operation during the latching/releasing process, the brew chamber  14  moves up and down a few millimeters relative to the carafe  12 . The housing  16  includes a latch  70  that can be rotated to place the vacuum coffee maker  10  into a locked “brew” position (shown in FIG. 1) or an unlocked position (shown in FIG. 2) so that the carafe  12  can slide into the housing  16  or out of the housing  16 . When the carafe  12  is slid into the housing  16 , the mating surfaces, or o-rings  29 , are not compressed against the brew strength adjuster  28  and no seal is formed. By rotating the latch  70  to the “brew” position, the brew chamber  14  will move towards the carafe  12  so that the o-rings  29  compress against and form a seal with the brew strength adjuster  28 .  
         [0029]    The slight vertical movement of the brew chamber  14  allows joining the brew chamber  14  and carafe  12  by sliding the carafe  12  horizontally under the brew chamber  14 . A horizontal, or substantially horizontal sliding motion of the carafe  12  provides for easy operation of the system by a consumer. FIG. 2 illustrates two horizontal grooves  17  located in the base  19  of the housing  16  for aligning the seals of the carafe  12  with the brew chamber  14 . The base  42  of the carafe  12  has two complimentary protrusions that engage and slide within the grooves  17 . In other embodiments, the carafe  12  and brew chamber  14  can be aligned using tracks or grooves located on the upper surface of the carafe  12  and lower surface of the brew chamber  14 . One of ordinary skill in the art can appreciate the different configurations allowing for the two chambers to be aligned.  
         [0030]    The tip  63  of the nozzle  62  contains an array of openings  65  that are sized and shaped to properly release the water and steam into the mixture of grounds and water. There is a risk of splashing and spilling grounds outside the filter  48 . To prevent this, the openings  65  in the nozzle  62  are large enough to prevent fine bubbles that can produce foam in the mixture, but small enough to act as diffusers, preventing large bubbles from forming that can produce messy slops and bursts from the surface of the mixture.  
         [0031]    The dual flow path system allows the use of a filter  48  that completely contains the grounds&#39; for easy disposal after use. This type of filter is called a “basket filter.” The single flow path of other vacuum-type coffee brewers does not allow the use of convenient basket filters, because boiled water cannot be pushed up a single flow path through the bottom of a paper filter. The boiled water must be ducted through a flow path around the filter  48  and released into the filter  48  from above. However, to prevent contaminating the coffee with grounds, the flow path around the filter  48  (through first and second flow tubes  50  and  54 ) cannot be used for aspiration of the coffee into the carafe  12 ; therefore, the “aspiration” flow path is required to draw the coffee through the filter and into the carafe  12 .  
         [0032]    In one embodiment, the brew chamber lid  71  includes tabs or fingers mounted to the underside of the lid  71  for retaining the upper edge of the filter  48  when the lid  71  is closed, thereby holding the filter  48  in its “basket” shape throughout the brewing process. This avoids spillage of grounds that could contaminate the finished coffee.  
         [0033]    When the latching sealing means is deactivated, the carafe  12  is freed from the upper chamber  14 . The carafe  12  can then be slid out horizontally for use as a serving pitcher. A horizontal sliding motion of the carafe  12  provides for easy, intuitive operation of the system by the consumer.  
         [0034]    Operation  
         [0035]    After placing coffee grounds into the filter  48 , filling the carafe  12  with water to the desired level and placing the carafe  12  back into the housing  16 , a user turns the heater  44  to the “full hot” position. The water begins to heat and the pressure of the air in the headspace above the water in the carafe  12  starts to increase. The partial pressure of the steam in the headspace increases with the rising temperature of the liquid water. The vent hole  40  acts as a vent to relieve this slow, early buildup of air and steam pressure. The water in the carafe  12  begins to boil.  
         [0036]    The amount of steam produced by the full boil cannot be vented fast enough by the vent hole  40  in the standpipe  32  and the pressure in the carafe  12  rises rapidly. The rapidly rising pressure forces the boiling water up the standpipe  32 . The water travels through the “fill and brew” check  56  valve in the manifold, up around the filter through the second flow tube  54 , and down through the nozzle  62  into the grounds in the filter. The water pouring out of the nozzle  62  is just below the boiling point.  
         [0037]    As the water level in the carafe  12  drops below the lower end  36  of the standpipe  32 , a high volume of steam begins escaping up the standpipe  32 . The steam travels through the pathway around the filter (first and second flow tubes  50  and  54 ), and is released by the nozzle  62  into the mixture of boiled water and grounds. The steam bubbles up through the full immersion mixture of water and grounds, agitating the mixture and keeping the mixture from cooling. This “steam powered” heating and mixing process continues until very little or no water is left in the carafe  12 . The length of time for the mixing process depends on the volume of water left in the carafe  12  at the time of the “unporting” of the lower end  36  of the standpipe  32 . By twisting the brew strength adjuster  28  and adjusting the height of the lower end  36  of the standpipe  32  above the bottom of the carafe  12 , the mixing time can be adjusted. When the boiling water level finally drops below a certain point exposing some or all of the heat transfer surface(s), a temperature rise is sensed in the heating element or in some other part of the heat transfer surfaces thermally connected to the heater  44 . The heater  44  tuns off, or the current to the heater  44  is reduced, and the boiling stops.  
         [0038]    By this time there is little or no air left in the carafe  12 . The carafe  12  is filled with steam. When the boiling stops, the steam condenses to a fraction of its gaseous volume and creates a strong partial vacuum in the carafe  12 . The partial vacuum forcefully pulls the brewed coffee in the upper chamber  14  through the filter and down through the drain check valve  60  and into the carafe  12 . The grounds are left inside the basket filter. Finally, a user can release the latching sealing means, freeing the carafe  12  from the upper chamber  14 . At that point, the carafe  12  can be slid out for use as a serving pitcher.  
         [0039]    In other embodiments, the brewing system described herein can be used for brewing tea, or other brewed beverages. The present invention should not be construed as being limited to brewing coffee.  
         [0040]    The foregoing description of preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to one of ordinary skill in the relevant arts. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalence.