Abstract:
A backup power supply system of a water heater includes a power transforming device and a controller. The power transforming device generates a DC current with an initial voltage through sensing the temperature change under a low battery condition. The controller examines the initial voltage of the DC current and gives command to which device to supply power to the water heater or to amplify the initial voltage of the DC current for maintaining the water heater&#39;s normal work.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to a water heater, and more particularly to a method of supplying a power vent or a direct vent water heater a backup power when the main power is off and the backup power supply system thereof. 
         [0003]    2. Description of the Related Art 
         [0004]    A conventional water heater, such as water heater, gas stove or fireplace, burns the gas by discharging. The power for discharging must be a DC power, which is usually obtained from converting an AC power or from a battery. In other words, a stable power supply is very important for the water heater to provide hot water. 
         [0005]    In a case of converting the AC power into the DC power, the wires may be broken in situations such as being pulled apart by someone or snapped off by animal, which cuts off the power supply and the water heater doesn&#39;t work until the power is recovered again. In winter time, it is cold and everything is covered by snow, which makes it difficult to recover the power when the power for the water heater is off, and thus causes a great deal of inconvenience. 
         [0006]    Some water heaters provide a backup battery to supply power when the power is off. Another type of water heater provides the battery for discharging. User only needs to replace a new battery when the power is out. However, the battery has a limited power supply that the battery cannot afford to maintain a water heater equipped with electronic devices and air blower. Batteries need to be replaced frequently and it is very inconvenient when the user can&#39;t find the battery. 
       SUMMARY OF THE INVENTION 
       [0007]    The primary objective of the present invention is to provide a method of supplying backup power to a water heater and a backup power supply system thereof, which transform the heat of the combustor into electrical power to maintain the water heater&#39;s work when the battery is in low battery condition. 
         [0008]    According to the objective of the present invention, a backup power supply system of a water heater includes a power transforming device and a controller. The power transforming device transforms the heat of a combustor of the water heater into a DC current with an initial voltage. The controller includes an examining unit and a voltage regulator. The examining unit is preset with a reference voltage and a working voltage. The controller gives command to a DC power supply to supply power to the power needed module when the initial voltage is lower than the reference voltage. The controller gives command to the power transforming device to supply the DC current to the power needed module when the initial voltage is higher than or identical to the working voltage. The voltage regulator amplifies the initial voltage into the working voltage to supply the power needed module power when the initial voltage is between the reference voltage and the working voltage. 
         [0009]    The method of supplying a backup power including the following steps: Providing a hot junction and a cold junction to sense temperatures. Generating a DC current with an initial voltage when a temperature sensed by the hot junction is higher than a temperature sensed by the cold junction, and then examining the initial voltage of the DC current. 
         [0010]    A controller gives command to a DC power supply to supply power to the power needed module when the initial voltage is lower than the reference voltage. 
         [0011]    The controller supplies the DC current to the power needed module when the initial voltage is higher than or identical to the working voltage; and 
         [0012]    The controller amplifies the initial voltage into the working voltage to supply the power needed module power when the initial voltage is between the reference voltage and the working voltage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a front view of the water heater of a first preferred embodiment of the present invention; 
           [0014]      FIG. 2  is a left view of the water heater of the first preferred embodiment of the present invention; 
           [0015]      FIG. 3  is a sketch diagram of the thermo-electric cooling chip of the first preferred embodiment of the present invention in the closed condition; 
           [0016]      FIG. 4  is a flow chart of supplying the backup power of the first preferred embodiment of the present invention; 
           [0017]      FIG. 5  is a left view of the water heater of a second preferred embodiment of the present invention equipped with the thermocouple; and 
           [0018]      FIG. 6  shows the closed loop of the thermocouple. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    The first preferred embodiment of the present invention provides a water heater  1 , as shown in FIGS. From  FIG. 1  to  FIG. 4 , includes a case  10 , a combustor  12 , a blower  14 , a water pipe  16 , a DC power supply  18 , a power transforming device  20 , and a controller  22 . 
         [0020]    The combustor  12  includes a plurality of burners  12   a  arranged side-by-side in the case  10 . The combustor  12  is above the blower  14 , and the water pipe  16  is above the combustor  12 . The combustor  12  has several openings for flame  12   b  at a top thereof to produce flames and heat up the water pipe  16 . The water pipe  16  has a cold water section  16   a  and a hot water section  16   b . The blower  14  forces air to flow into the combustor  12  to be mixed with gas before burning. 
         [0021]    The DC power supply  18  is a battery mounted on a bottom of the case  10  in the present embodiment. The battery  18  supplies power to an ignition device  12   c  of the combustor  12 , the blower  14 , a screen  24 , and other electronic devices  26 . Hereafter, we call the blower  14 , the screen  24 , and the electronic devices  26  a “power needed module”  28 . It is noted that, in the water heater  1 , AC power is a main power to activate the power needed module  28  in normal conditions, and the battery is a backup power to supply power to the power needed module  28  when the main power is off. 
         [0022]    The power transforming device  20  is a thermoelectric cooling chip in the present embodiment having a plurality of N type semiconductors  20   a  and P type semiconductors  20   b  to form a closed loop  21 . The closed loop  21  includes a hot junction P 1  close to the hot water section  16   b  of the water pipe  16  and a cold junction P 2  close to the cold water section  16   a  of the water pipe  16 . In practice, the thermoelectric cooling chip may generate a voltage when it is operated reversely. For this condition, it is called thermoelectric power generating module. 
         [0023]    The controller  22  is electrically connected to the thermoelectric cooling chip  20  and has an examining unit  22   a  and a voltage regulator  22   b . The examining unit  22  has a logic circuit  22   c , in which a reference voltage V 1  and a working voltage V 2  are stored. The working voltage V 2  is a minimum voltage to activate the power needed module  28 . In the present invention, the reference voltage V 1  is 300 mV and the working voltage V 2  is 6V. These voltages can be any value according to the exact condition of the water heater. 
         [0024]    A control method of providing the backup power via the thermoelectric cooling chip  20  and the controller  22  when the main power is off and the battery  18  is in a low-battery condition is described hereunder: 
         [0025]    As shown in  FIG. 3  and  FIG. 4 , the battery  18  supplies the combustor  12  power for ignition. At this time, the thermoelectric cooling chip  20  senses a first temperatures T 1  of the cold water section  16   a  and a second temperature T 2  of the hot water section  16   b  through the hot junction P 1  and the cold junction P 2  to provide a DC current I with an initial voltage V. The controller will take different actions according to a temperature difference ΔT of the first temperatures T 1  and the second temperature T 2  (ΔT=T 1 −T 2 ). 
         [0026]    In a condition of the temperature difference ΔT (ΔT=T 1 −T 2 ) being less than a minimum difference (20° C. in the present invention), it means that the initial voltage V is greater than the reference voltage V 1  (300 mV). At this time, the controller  22  commands that the battery  18  supply power to the power needed module  28 . The battery  18  will soon run out, which will reach another condition described hereafter. This condition rarely happens because the reference voltage V 1  is set low. 
         [0027]    In a condition of the temperature difference ΔT (ΔT=T 1 −T 2 ) being identical to or greater than a maximum difference (90° C. in the present invention), it means the initial voltage V is greater than the working voltage V 2  (6V). At this time, the thermoelectric cooling chip  20  transforms the thermal energy into electric power to provide the power needed module  28  a DC current I directly that the blower  14 , the screen  24  and the electronic devices work by the DC current I rather than the power of the battery  18 . 
         [0028]    In a condition of the temperature difference ΔT (ΔT=T 1 −T 2 ) being in a range between the minimum difference and the maximum difference (20° C. and 90° C.), it means that the initial voltage V is between 300 mV and 6V. At this time, the controller  22  activates the voltage regulator  22   b  to amplify the voltage to have an amplified voltage V 3 . In the present embodiment, the voltage regulator  22   b  amplifies the voltage 20 times. However, the voltage regulator  22   b  may amplify the voltage to any value according to the exact need. After that, the controller  22  activates the logic circuit  22   c  of the examining unit  22   a  to examine the amplified voltage V 3  to demand that thermoelectric cooling chip  20  provide power when the amplified voltage V 3  is greater than 6V or to demand that the battery  18  provide power when the amplified voltage V 3  is less than 6V. 
         [0029]    In conclusion, the present invention provides the power transforming device a method to transform thermal energy into electric power and lowers the barrier of amplifying the voltage to provide the power needed module sufficient power by amplifying the voltage in a specific condition. The present invention may maintain the water heater&#39;s normal work even when the AC power supply is off. 
         [0030]      FIG. 5  and  FIG. 6  show the second preferred embodiment of the present invention, in which the power transforming device is a thermocouple  30 . The thermocouple  30  is electrically connected to the controller  22 . The thermocouple  30  has two different conductive materials to form a closed loop  30   a . The closed loop  30   a  has a hot junction P 1  to sense a first temperature T 1  and a cold junction P 2  to sense a second temperature T 2 . The hot junction P 1  is arranged at a position close to the openings for flame  12   b  of the burners  12   a . The closed loop  30   a  generates a DC current I with an initial voltage V when the first temperature T 1  is greater than the second temperature T 2 . The controller  22  of the second preferred embodiment does the same procedures as the first preferred embodiment according to the initial voltage V to maintain the water heater&#39;s work. 
         [0031]    The description above is a few preferred embodiments of the present invention and the equivalence of the present invention is still in the scope of claim construction of the present invention.