Abstract:
A water heating unit uses a voltage transformer type heating unit to heat water. The water flows from a water reservoir to a wound transformer where the water passes through metal tubing that is also the secondary winding of the transformer. The secondary winding is shorted and an erect-magnetic field induces a current in the transformer generating heat that heats the water flowing through the metal tubing. The turns of the primary winding of the heating unit can be separated with spacer material and a cooling fan can be included adjacent to the heating unit for forcing air in between the turns of the primary winding to remove excess heat.

Description:
This application is a continuation-in-part of application Ser. No. 09/130,947 filed on Aug. 7, 1998 now U.S. Pat. No. 6,078,032. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to water heating units. More particularly, the present invention relates to water heating units which use a voltage transformer type water heating unit to heat water. 
     BACKGROUND INFORMATION 
     Generally, hot water beverage makers such as flow-through coffee makers and other water heating units, such as home hot water heaters, consist of a reservoir of water that allows fluid flow to a heating device. Prior art water heating units include electrical resistance coils submerged in or adjacent to the fluid. In another example of a prior art water heating unit, a microwave generator is used to heat water flowing adjacent to the microwave generator. While microwave energy may be more efficient than electrical resistance coils, stray microwave radiation is a danger to people who wear heart pacemakers, and microwave generators are more expensive to construct. 
     As such, there is a need for an inexpensive water heating unit with an improved water heating unit for heating water. 
     SUMMARY OF THE INVENTION 
     These needs and other needs are satisfied by the water heating unit with voltage transformer type water heating unit of the present invention. A first object of the invention is to provide an efficient water heating unit comprised of a voltage transformer type heating unit with a hollow and electrically shorted secondary winding for heating water. 
     A second object of the invention is to provide a heating unit that may operate at various primary input voltages. 
     A third object of the invention is to provide a voltage transformer type heating unit that has over temperature protection in the secondary winding. 
     The water heating unit of the present invention comprises a water supply means, a voltage transformer type water heating unit, a power supply, and a water dispenser. The water flows through tubing from the water supply means to a voltage transformer type heating unit where the water passes through electrically conductive tubing that is also the secondary winding of the transformer. The secondary winding is shorted to form a closed electrical circuit with an in-series electrical safety device. 
     In one application of the present invention, the water, which is heated when flowing through the secondary winding, can then be passed through a filtering vessel that may contain ground coffee or tea and ultimately into a carafe for serving, or the heated water can be mixed with a powdered beverage mix, such as cocoa, to make the hot beverage. The voltage transformer type heating unit is wound such that relatively high electrical current and low voltage is generated in the secondary winding so as to maximize heating of water flowing through the transformer. 
     Further objects, features and advantages of the present invention will become apparent from the following description and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic representation of a hot water beverage maker including a water heating unit made in accordance with this invention. 
     FIG. 2 is a cut away side view of the voltage transformer type heating unit of FIG.  1 . 
     FIG. 3 is a schematic view of the power input to the voltage transformer type heating unit of FIG.  2 . 
     FIG. 4 is an enlarged view of portions of the secondary winding. 
     FIG. 5 is an enlarged view of an alternative embodiment of the secondary winding. 
     FIG. 6 is an exploded perspective view of an alternative embodiment of a voltage transformer type heating unit according to the present invention. 
     FIG. 7 is a cross-sectional view of the heating unit of FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In accordance with the present invention, a water heating unit with voltage transformer type water heating unit is described that provides distinct advantages when compared to those of the prior art. The invention can best be understood with reference to the accompanying drawing figures. 
     Referring now to the drawings, a hot water beverage maker including a water heating unit according to the invention is generally designated at reference numeral  10 . One embodiment of such a hot water beverage maker  10 , shown in FIG. 1, comprises a hot coffee maker for brewing hot coffee. Alternative embodiments can be configured to make hot tea, hot water or various other hot beverages. 
     Referring to FIGS. 1 and 2, the hot water beverage maker  10  comprises a water supply means, such as a water reservoir  12 , a voltage transformer type heating unit  14 , a power supply  16  and a water dispenser  18 . The voltage transformer type heating unit  14  comprises a primary winding  20  and a secondary winding  22 . Preferably, the voltage transformer type heating unit  14  also includes a coupling core  24 . The secondary winding  22  comprises flow through, hollow tubing having a water inlet  26  at one end and a water outlet  28  at the opposite end. The construction of the voltage transformer type heating unit  14  will be more specifically discussed below. 
     The water reservoir  12  is contained within a coffee maker housing or frame  30 . Alternatively, the water supply means may comprise a port for receiving water from an external water source such as a water faucet or other externally piped water source. As shown in FIG. 1, the water reservoir  12  is connected to the secondary winding  22  at the secondary winding water inlet  26  by heating unit tubing  32 . Preferably, the heating unit tubing  32  is connected near the bottom of the water reservoir  12  and provides water from the water reservoir  12  to the secondary winding  22 . 
     The secondary winding  22  is hollow to allow water to flow from the water inlet  26  through the secondary winding  22  to the water outlet  28 . The secondary winding  22  is comprised of electrically conductive material, preferably copper tubing. The secondary winding  22  heats water flowing through it as described subsequently. 
     The water outlet  28  of the secondary winding  22  is connected to the water dispenser  18  by filtering vessel tubing  34 . Tubing  34  directs water from the secondary winding  22  to the water dispenser  18 . Preferably, a check valve  33  is disposed along tubing  34  between the water outlet  28  and the water dispenser  18  to prevent water from flowing back into the secondary winding  22 . 
     Pre-heater/flow control tubing  36  may be connected between the heating unit tubing  32  and the water inlet  26  of the secondary winding  22 . The pre-heater/flow control tubing  36  extends between and provides water from the heating unit tubing  32  to the water inlet  26  of the secondary winding  22 . In this manner, water is allowed to flow from the water reservoir  12  through the heating unit tubing  32 , pre-heater/flow control tubing  36 , secondary winding  22 , and filtering vessel tubing  34  to the water dispenser  18 . 
     Preferably, water dispenser  18  comprises a nozzle that directs heated water into the filtering vessel  37 . The filtering vessel  37  is removably secured to the housing  30  and is designed to accept a filter (not shown) and ground coffee beans  38 . The filtering vessel  37  can also accept tea leaves, etc. for brewing various other hot water beverages. Alternatively, the water dispenser  18  can include a faucet  39  for dispensing hot water. In this manner, a user can dispense hot water that can be mixed with a powered beverage mix, such as cocoa, to produce a hot cocoa. 
     Hot water dispensed into the filtering vessel  37  is filtered through the ground coffee beans  38 , thus producing hot liquid coffee  42 . The filtering vessel  37  includes a discharge nozzle  40  aligned to allow the flow of hot liquid coffee  42  from the filtering vessel  37  into a carafe  44 . The hot water beverage maker  10  includes a carafe filling and storage location  46  shaped to accept the carafe  44  on a hot plate  48 . 
     As mentioned above, the voltage transformer type heating unit  14  generally comprises a primary winding  20 , a secondary winding  22  and a coupling core  24 . Preferably, the voltage transformer type heating unit  14  is contained within the inside of the housing  30 . The voltage transformer type heating unit  14  is a wound transformer with each subsequent component wound around the next and having insulation  50  between each successive layer. 
     In a preferred embodiment, the coupling core  24  is comprised of an inner core section  52  and an outer core section  54 . The inner core section  52  and outer core section  54  are made of a ferromagnetic material, such as iron. Preferably, the primary winding  20  comprises a first half primary winding section  56  and a second half primary winding section  58 . The first half primary winding  56  is wound around the inner core section  52 . The second half primary winding section  58  is wound around the first half primary winding section  56 . The secondary winding  22  is wound around the second half primary winding section  58  and the outer core section  54  is formed around the secondary winding  22  The pre-heater/flow control tubing  36  is wrapped around the first half primary winding section  56  between the first half primary winding section  56  and the second half primary winding section  58 . 
     Referring to FIG. 3, the primary winding  20  comprises an electrically conductive wire wound in a predetermined number of turns. The power supply  16  is electrically connected to the primary winding  20 . The primary winding  20  has multiple voltage inlet taps  60  for providing electrical power to the primary winding  20 . The multiple power taps  60  are configured for receiving different input signals to allow the primary winding  20  to be powered by various alternating and direct current electrical power sources such as  120  VAC,  208  VAC and  220 / 240  VAC. 
     A transformer controller  61  shown in FIG. 1, electrically connected to the power supply  16 , regulates and controls the current supplied to the primary winding  20  by the power supply  16 . In a preferred embodiment, the transformer controller  61  comprises a Triac controller. 
     The secondary winding  22  is comprised of electrically conductive hollow tubing wound into a predetermined number of turns. In order to make an completed closed electrical circuit, a shorting wire  62  may be connected between the water inlet  26  and water outlet  28  of the secondary winding  22 , as shown in FIG.  2 . Preferably, the shorting wire  62  includes an in-series mechanical overcurrent electrical safety device  64  such as an electrical fuse interposed between the water inlet  26  and water outlet  28  for preventing damage to the hot water beverage maker  10  due to excessive heat in the secondary winding  22 . 
     Alternatively, as shown in FIG. 4, an electrical closed circuit can be formed with the secondary winding  22  by soldering together the water inlet and outlet end portions  22   a  and  22   b,  respectively, of the secondary winding  22  near the water inlet  26  and water outlet  28 , using tube connecting solder  70 . In this manner, the end portions  22   a  and  22   b  overlap along their lengths. Instead of losing the heat that the shorting wire would generate along its length, the connection of the end portions of the secondary winding insures that all heat generated due to resistance losses of current flow through the secondary winding  22  is absorbed by water flowing through the secondary winding  22 . In other words, heat generated in the shorting wire  62  described above, which is normally lost, is recovered and absorbed by water in the secondary winding  22 . 
     Preferably, end portions  22   a  and  22   b  of the secondary winding  22  tubing are soldered together under tension, as shown by tension lines  72 , forming a spring device. A tube connecting solder  70  can be chosen that has melting characteristics such that it will melt at a predetermined temperature. Thus, if the secondary winding  22  exceeds the predetermined temperature, such as when there is excessive current in the secondary winding  22 , the tube connecting solder  70  fails and the tension  72  forces the secondary winding  22  to separate at the water inlet  26  and water outlet  28 , thereby forming an electrical open circuit. If the secondary winding  22  forms an electrical open circuit, power consumption is reduced to a minimum and the secondary winding  22  is allowed to cool down. In this manner, the tube connecting solder  70  acts in a capacity similar to the above-mentioned in-series mechanical overcurrent electrical safety device  64  to protect the beverage maker  10  from damage due to excessive current or excessive temperature situations. 
     As shown in FIG. 5, tension springs  74  and  76  can be connected at one end to the secondary winding  22  near the water inlet end  22   b  and water outlet end  22   b,  respectively, and at the other end to the coupling core  20 . Preferably, insulated brackets  78  and  80  are used to connect the tension springs  74  and  76  to the coupling core  24 . The tension springs  74  and  76  provide tension near the end portions  22   a  and  22   b  of the secondary winding  22  to ensure that the end portions  22   a  and  22   b  are separated when the tube connecting solder  70  melts. 
     In operation, when current is supplied to the primary winding  20  by the power supply  16 , an electromagnetic field is created around the primary winding  20 . The electromagnetic field couples with the secondary winding  22  inducing a current in the secondary winding  22 . The shorting wire  62  or tube connecting solder  70  connected between the water inlet  26  and water outlet  28  completes an electrical closed circuit with the secondary winding  22 , and electrical resistance in the electrical closed circuit causes the secondary winding  22 , including any water in it, to heat up. 
     The coupling core  24  couples with the primary winding  20  and secondary winding  22 . Because the coupling core  24  is composed of ferromagnetic material, there is enhanced coupling between the primary winding  20  and secondary winding  22 . The primary winding  20  and secondary winding  22  are wound such that relatively high electrical current and low voltage is generated in the secondary winding  22  so as to maximize heating of the water in the secondary winding  22 . This is accomplished by having a lesser number of turns in the secondary winding  22  than in the primary winding  20 . 
     Heated water flows from the secondary winding  22 , through the check valve  33  into the filtering vessel tubing  34 , and on to the water dispenser  18 . Preferably, a temperature sensor  66  (FIG. 1) is disposed between the secondary winding  22  and water dispenser  18  near the water outlet  28 . The temperature sensor  66  measures the temperature of the heated water exiting the secondary winding  22 . 
     The temperature sensor  66  is electrically connected to the transformer controller  61 . The temperature sensor  66  provides a control signal to the transformer controller  61  indicative of the measured temperature of the heated water. The transformer controller  61  regulates and adjusts the current supplied to the primary winding  20  to maintain a pre-set water temperature range. 
     The temperature sensor  66  may include a high temperature cutout switch  67  that sends a shutdown signal to the transformer controller  61  if the measured temperature of the heated water exceeds a predetermined maximum temperature. In this situation, the temperature controller  61  shuts off the current supplied to the primary winding  20  by the power supply  16 . 
     As heated water leaves the secondary winding  22  and flows through the check valve  33 , water is drawn into the secondary winding  22  from the water reservoir  12  through the heating unit tubing  32  and the pre-heater/flow control tubing  36 . Water flowing through the pre-heater/flow control tubing  36  absorbs heat from and thus cools the primary winding  20 . Preferably, the pre-heater/flow control tubing  36  comprises non-conducting, thin-walled tubing, such as plastic tubing, so that the tubing does not heat up as current is conducted through the tubing  36 . This tubing permits the transformers to more efficiently heat the water. 
     The partially heated water then flows through the secondary winding  22  where it is further heated by resistance losses of the current flow through the secondary winding  22 . The fully heated water exits the secondary winding  22  and flows to the water dispenser  18  via the check valve  33  and filtering vessel tubing  34 . 
     The water dispenser  18  directs water through ground coffee beans  38  held in the filtering vessel  37  creating hot liquid coffee  42 . The hot liquid coffee  42  may be collected in a carafe  44  held on a hot plate  48  in the carafe filling and storage location  46 . 
     One alternative embodiment of the water heating unit of the present invention is shown in FIGS. 6 and 7. In this embodiment, the primary windings  20  each include insulating spacer material  82  so as to provide space between each primary winding layer  21  (i.e. each primary winding turn). This space allows for substantial amounts of air to pass between each primary winding layer  21 , thus removing excess heat and preventing overheating. 
     The spacer material is preferably glastic sticks, which separate and insulate the layers of primary windings from one another. The sticks of spacer material are also spaced apart from each other, such as near the corners of the rectangular shaped heating unit of FIG.  7 . In this manner, most of the surface area of the primary windings is exposed to air which, as described above, prevents overheating of the unit. 
     In addition to natural air flow (convection) through the spaces between the primary winding layers  21 , a cooling fan  84 , shown in FIG. 6, can also be added to further increase air flow. The cooling fan  84  is positioned adjacent to the primary winding  20  for forcing larger amounts of air through the spaces between the primary winding layers  21 . 
     To increase the efficiency of the cooling fan  84 , a shroud or housing  86  surrounds the fan  84  to direct the air flow generated by the cooling fan  84  into the spaces between the primary winding layers  21 . The shroud  86  comprises a central chamber  88  in which the cooling fan  84  is located and outer wings  90  for connecting the shroud  86  to a heating unit housing  92  which surrounds the heating unit  14 . Preferably, the central chamber  88  walls  94  are angled to direct air flow generated by the cooling fan  84  into the spaces between the primary winding layers  21 . 
     It will be apparent to those skilled in the art that modifications may be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited except as may be necessary in view of the appended claims.