Patent Publication Number: US-2013243919-A1

Title: Espresso Maker and Method

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 13/331,548, which is a continuation-in-part of U.S. patent application Ser. No. 12/070,249, filed Feb. 15, 2008, and claims the benefit of United States Provisional Patent Application No. 60/902,010, filed Feb. 16, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of devices and methods used to produce coffee drinks, and more particularly to devices and methods used to produce espresso. Even more particularly, the invention relates to such devices and methods that utilize compressed gas to produce the coffee drinks. 
     Coffee and espresso makers are well known, with the devices ranging in size from those producing a single cup at one time to those producing multiple cups. Espresso is a coffee drink that is made using hot water at higher-than-atmospheric pressure so as to extract more soluble compounds from the coffee beans than is extracted in the production of standard coffee, the water being forced through finely ground coffee beans. The added pressure extracts desirable compounds that are left behind in other brewing methods, producing a thick, strong coffee drink with naturally occurring emulsified oils. Espresso drinkers tend to be very particular about the taste of the product, and it is imperative that an espresso maker be able to achieve the necessary temperature and pressure during the process, because failure to do so produces an inferior product. Most espresso making machines are therefore relatively expensive pieces of equipment. 
     Attempts to produce an espresso maker that is small, relatively inexpensive and portable have been generally unsuccessful to date, as these requirements usually result in a device which cannot produce sufficient pressure, sufficient temperature, or both, and which attempts to produce espresso with a method which cannot produce a true espresso drink that satisfies connoisseurs of the beverage. 
     A recent approach has been to utilize compressed gas from a small gas cylinder or canister, whereby the gas is used to force a measured quantity of hot water through the ground coffee beans, often retained within a permeable pod, and into a small cup or other container. Once the water has been fully evacuated, the gas pressure is then shut off. Examples of this type of system can be found in U.S. Patent Application Publication No. 2007/0199452 to Dworzak et al., in WIPO Publication No. WO/12007/088309 to Handpresso, and in a commercial product currently being marketed under the brand HANDPRESSO. In all of these devices, the compressed gas acts in the manner of a piston—the gas merely forcing the water through the coffee pod or ground coffee beans. A cup-sized quantity of water is provided within a chamber in the device, the water being either pre-heated or subsequently heated by the device itself. The coffee filter pods or ground coffee beans are then placed into the device, and the compressed gas is released to move the water. In the Dworzak published application, the compressed gas is directed into the water chamber, which is separated from the ground coffee beans by a tubular conduit. As the pressure rises, the water is pushed through the conduit and through the ground coffee beans or filter pod. In the Handpresso devices, a gas chamber separate from the water chamber is first pressurized up to a desired minimum pressure by release of gas from a cylinder or by a hand pump. The water and coffee filter pod are then added to the device, and the gas is released from the gas chamber. In all these devices, as soon as the compressed gas is released, water flow commences through the ground coffee beans into the cup. Because the compressed gas is used merely to force the water through the ground coffee beans or filter pod, the pressure against the water begins to diminish immediately as liquid flows into the cup. All brewing or infusion, i.e., the transfer of compounds and emulsified oils to the hot water to create the espresso liquid occurs only while the water passes through the filter pod. 
     It has been discovered that a more flavorful cup of espresso may be produced utilizing a different device and method, wherein instead of using the compressed gas as the means to drive the water through the ground coffee beans with immediate release of liquid upon release of the compressed gas, the compressed gas is used to bring the combination of water and coffee up to a minimum desired pressure in a closed chamber. In other words, the chamber containing the hot water and the coffee pod or ground coffee is pressurized after the water has been in contact with the ground coffee beans for a short period of time such that infusion has already begun and then continues to occur under elevated pressure. After the minimum desired pressure has been attained in the water/coffee chamber, infusion is allowed to occur for another short period of time and then the liquid espresso is released into the cup by opening a manual release valve. 
     It is an object of this invention to provide an espresso maker capable of producing true espresso in single cup batches, wherein compressed gas is used to bring a chamber containing hot water and ground coffee beans up to a minimum desired pressure for optimum infusion prior to release of the liquid espresso into a cup or other container, the liquid espresso being held in the device by a manually operated release valve. It is a further object to provide such an invention in various embodiments, such that the invention may be small, portable and handheld, or may be a stand-alone countertop embodiment suitable for use in a kitchen or for transport on a wheeled cart. It is further object to provide such an invention wherein preferably the compressed gas is provided by a cylinder or small canister, and wherein various gases may be utilized. 
     SUMMARY OF THE INVENTION 
     The invention is a small, portable hand-held or table-top espresso maker device and the method of using this device to produce espresso in single cup or small batch serving sizes. In a handheld embodiment, the device comprises a cap member removably joined to a base member, both being composed of material that is able to withstand high pressure and temperature. The base member and cap member in combination define a closed water chamber to receive water and a coffee filter pod. Coffee filter pod securing means are provided such that a filter pod containing ground coffee beans is retained above the major portion of the water chamber, i.e., adjacent or relatively near one end of the water chamber. A pressurization inlet valve is provided such that the chamber pressure can be raised (preferably up to at least approximately 15 bars or 217 psi for espresso) by the introduction of pressurized gas from a pressurized gas dispenser, or by the use of a hand pump or the like. While the desired pressurization could be achieved using automatic metering systems, preferably a visual pressure gauge is provided such that the chamber pressure can be easily monitored from the outside of the device. A release outflow valve is provided in the cap member to release the espresso into a cup or other container for consumption after an appropriate time period, the release outflow device being of a type such that the valve remains open throughout the entire dispensing procedure, unless manually closed. The release valve preferably is of a type having an adjustable opening size, such that the flow rate of the espresso can be adjusted as desired either before or during the dispensing procedure. 
     The method of producing espresso comprises the steps of introducing hot water into the base chamber, or providing water in the chamber and then heating it using resistance heaters, microwaves or other heating means, securing a coffee filter pod between the base member and the cap member, allowing the water to contact the coffee filter pod, allowing infusion to occur for a short time period, and then introducing pressurized gas into the chamber to raise the pressure of the water/coffee infusion. Because the hot water is in contact with the filter pod before, during and after pressurization is achieved, the coffee extracts are infusing into the water during the entire pressurization event. When the internal pressure has reached the desired minimum pressure (most preferably approximately 15 bar for espresso), the gas flow is stopped, the infusion is allowed to occur for another short time period, which determines the strength of the espresso, and the release outflow valve is opened, whereby the pressure within the chamber drops and the espresso slowly flows from the device into the cup. Adjusting the size of the opening created by the release valve to vary the flow rate determines the quality result and enhances crema characteristics. 
     In alternative embodiments the equivalent operative components and structural elements are positioned within a stand-alone or table-top housing, such that the unit may be used in a kitchen counter-top setting or moved about on a wheeled cart. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of an embodiment of the invention, shown partially in cross-section. 
         FIG. 2  is a view of the embodiment of  FIG. 1  showing the cap member joined to the base member and a pressurized gas dispenser connected to the pressurization valve. 
         FIG. 3  is an exploded view of an alternative embodiment of the base and cap member. 
         FIG. 4  is a cross-sectional view of a representative manually operated release valve. 
         FIG. 5  is a view of a table-top embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings, the invention will now be described in detail with regard for the best mode and the preferred embodiment. In general, the invention is an espresso maker device and the method of producing espresso using the device. For ease of discussion, the invention will be described below primarily with regard for its use as an espresso maker, but with the understanding that it could be used to make regular coffee by operating the device at a lower pressure. 
     In the embodiment shown in  FIGS. 1 and 2 , the device comprises a base member  11  having a generally cup-like configuration defining an open-topped, sealable chamber  12 . Chamber  12  is sized so as to be able to receive and retain approximately 1.75 ounces of water, which is a suitable amount to produce a typical espresso shot. A pressurization port  13  is provided in the wall of the base member  11 , the pressurization port  13  receiving a pressurization valve  51  such that pressurized gas may be introduced into the chamber  12  using suitable pressurization means  90  for raising the pressure within the chamber  12  by delivering compressed gas into the chamber  12 , such as a gas canister  91 , a hand pump, electric air pump, etc. For the production of espresso, the pressurization means  90  should preferably be capable of pressurizing the chamber  12  up to or in excess of approximately 15 bar (about 217 psi) when it is retaining water. This pressure can be reached very rapidly using a small, trigger-operated gas canister  91  due to the small volume of the chamber  12 . The device further comprises a cap member  21 , the cap member  21  having a liquid release port  22  to receive a drain or liquid release outflow valve  53 . Optionally, the device may further comprise a pressure relief port  23  (which could also be disposed in the base member  11 , or omitted entirely) to receive a pressure relief safety valve  54 . Preferably, the cap member  21  is provided with gripping means  24 , such as a textured annular surface, a handle, etc., to provide a means to more easily tighten and release the cap member  21  from the base member  11 . Connecting means  30  are provided for joining the cap member  21  to the base member  11  in a tight, secure, yet releasable manner, such as for example a combination of threading  31 , mechanical latches, hinges, slots and tabs, etc. The base member  11  and the cap member  21  are composed of material able to withstand high pressure and high temperature, such as for example, aluminum, stainless steel, ceramics, specialty polymers, etc. Proportions, dimensions and configurations may vary somewhat without departing from the spirit of the invention. 
     The device further comprises means  40  for retaining a ground coffee bean infusing member  60 , such as a coffee filter pod  61 , at or adjacent the top of the chamber  12  in the base member  11 , coffee filter pods  61  being known in the art and typically comprising a disk-shaped body retaining a quantity of finely ground coffee and a peripheral skirt or flange member  62 . Alternatively, a reusable, finely perforated infuser member (not shown) made of stainless steel or the like could be used in place of the pre-manufactured filter pods  61  to retain fresh ground coffee beans. The infusing member retaining means  40  must be able to retain the pod filter  61  in a manner such that water contained in the base member chamber  12  is forced through the pod filter  61  under pressure, which is typically accomplished by clamping the pod skirt  62  between two opposing annular surfaces. In the embodiment shown in  FIGS. 1 and 2 , the infusing member retaining means  40  comprises a pair of channels or grooves  41  containing O-rings or similar gaskets  42 , such that the pod skirt  62  is secured between the two O-rings  42  when the cap member  21  is screwed onto the base member  11 . Alternatively, as shown in the embodiment of  FIG. 3 , one set of groves  41  and O-rings  42  can be replaced with a raised annular bead surface  71  to press the skirt  62  against the other O-ring  42 , or equivalent retention means could be utilized. With the pod filter  61  in place, all water must pass through the pod filter  61  to reach the release outflow valve  53 . 
     The liquid release outflow valve  53  is not a standard pressure activated valve of the type which automatically opens when a given pressure is reached within the chamber  12  and which closes when the pressure drops below a minimum value, as this would not allow for the retention of pressurized hot water within the chamber  12  after the desired pressure is reached, and would not allow for a complete drop in pressure back to atmospheric pressure as the liquid is fully discharged. Instead, the liquid release outflow valve  53  is of a type that is opened and closed manually or is opened in response to a non-pressure event or in addition to a pressure event. For example, the liquid release outflow valve  53  may be a manually operated ball valve, as shown in  FIG. 4 , comprising a housing  55  retaining a manually rotatable valve body  56  having an internal bore  57 , the bore providing a conduit between the inlet  58  and the outlet  59  such that the amount of rotation of the valve body  56  relative to the housing  55  determines the flow rate through the liquid release outflow valve  53 . Other types of manually controlled valves which allow control of the flow rate, such as a manually operated needle valve for example, may also be used. Alternatively, the liquid release outflow valve  53  may be a valve operated by a solenoid activated by a trigger, switch or button. Likewise, an alternative liquid release outflow valve  53  may comprise a system having a pressure-activated valve coupled with a timer to delay opening and a mechanism to maintain the valve in the open position throughout the entire discharge. Still another alternative liquid release outflow valve  53  may comprise a flow sensor to control the size of the opening in response to changes in flow rate. 
     Because the water and coffee filter pod  61  are subjected to high pressure prior to and during the release the water through the pod  61 , it is most preferred that a perforated pod support member  70  be provided between the coffee filter pod  61  and the outflow port  22 , such that rupture of the pod  61  is precluded during pressurization or liquid release. Most preferably, the pod support member  70  is a thin stainless steel member with relatively fine perforations to allow for liquid passage, the pod support member  70  being press-fit or otherwise suitably attached to the cap member  21 , as shown in  FIG. 3 . 
     Various types of valves and gauges may be utilized. For example, the pressurization valve  51  may comprise the type known as a Presta or Schrader valve. The pressure gauge  52  may provide an analog or digital readout, or may comprise a pop-up type valve. As described above, it is most preferable that the drain or release valve  53  be of a type that allows for a gradual release of pressure to insure that the espresso is released slowly rather than in a burst or as a strong stream. It is also contemplated that the device could be provided with external or internal thermal insulation means to improve its ability to retain temperature. 
     In an alternative embodiment of the device shown in  FIG. 3 , the gripping means  24  is shown to comprise a pair of extended handles that provide the means to rotate the cap member  21  relative to the base member  11  and to hold the device during the pressurization and infusion process. The handle connected to the base member  11  is a hollow conduit leading from the pressurization valve  51  to the chamber  12 , the pressurization valve  51  being mounted on the free end of the handle for attachment of the pressurization means  90 , to chamber  12 . 
     To make espresso, the user first heats water to boiling—either separately from the base member  11  or in the base member  11  itself, such as with a stove, a microwave, an electric immersion coil or the like. It is also possible to provide a removable receptacle that fits within the chamber  12 , such that the removable receptacle may be externally heated and then replaced in the chamber  12 . It is also possible to provide an internal heating element, such as a coil, that can be utilized in circumstances where electrical power is available. With the high temperature water (preferably at or above 185 degrees F.) poured into the chamber  12  of the base member  11 , the filter pod  61  is placed atop the base member  11  and the cap member  21  is joined to the base member  11 , thereby securing the filter pod  61  in place. The device is then inverted, for the handheld embodiment, such that the water contacts the filter pod  61 . After a period of at least about three seconds and preferably about eight to ten seconds to allow full hot water penetration of the filter pod  61  and the onset of infusion and brewing, the chamber  12  is pressurized (most preferably to at least approximately 15 bar), such as by delivering compressed gas from the compressed gas canister  91  through the pressurization valve  51 . Preferably nitrogen, nitrous oxide, oxygen, argon gas, carbon dioxide or a blend of these gases, is utilized. It has been found that of these gases, nitrous oxide produces the highest quality product. Alternatively, a hand pump or similar means could be used as the pressurization means  90  to deliver compressed air or other gas into the chamber  12 . The gas flow is then stopped and the pressure within the chamber  12  is held constant for a period of at least approximately three seconds and preferably about eight to ten seconds to allow infusion and steeping to occur under high pressure, the release valve  53  is opened to slowly release the espresso liquid into a container. Preferably, the espresso is released slowly over a period of about thirty seconds into the container. During the espresso release the pressure within the chamber  12  steadily decreases. Because the hot water is in contact with the filter pod  61  before, during and after the pressurization operation, infusion of the desirable compounds and oils from the finely ground coffee beans is optimized and continues until the liquid is released into the cup, thereby producing a strong, thick, high quality espresso drink with a naturally occurring crema. 
     An alternative embodiment of the invention is possible wherein a self-supporting housing is provided to receive the operative components, such that the device may be utilized for example on a counter-top or a movable cart as a stand-alone unit, as shown in  FIG. 5 . In this case, the brewing chamber  12  would be provided with an upper cap member  21  or a conduit means for delivery of the hot water into the chamber  12  after a coffee filter pod  61  has been disposed beneath the chamber  12 , such as by providing a hinged or fully removable lower body to provide access for placement and removal of the filter pod  61 . Appropriate seals would be utilized, and the manually operated release outlet valve  53  would be used to control residence time and release flow rate of the espresso. 
     One significant advantage to the invention over the prior art systems that do not provide a closed chamber  12  during pressurization, in addition to the production of a higher quality cup of espresso, is that the quantity of gas required to produce a cup of espresso is significantly reduced, since the only gas utilized is the small amount required to pressurize chamber  12 . In many of the known prior art systems that utilize gas as a continuous pump to push the water through the ground coffee, the gas runs continuously until after all the water has been expelled, thereby wasting a significant amount of gas and raising the brewing cost per cup. Another significant advantage to the invention is that the density or packing of the ground coffee is not a significant variable in producing a high quality espresso. Still another advantage to the invention is that the release outlet valve  53  may be fully opened to allow easier cleaning and flushing. 
     It is contemplated that equivalents or substitutions for elements set forth above may be obvious to those skilled in the art, and therefore the true definition and scope of the invention is to be asset forth in the following claims.