Abstract:
A method for controlling a gas-fired appliance is presented, wherein the gas-fired appliance includes a combustor, at least one flow-regulating valve, and a solenoid valve which are all interconnected, and adaptive to low or no power supplied to the gas-fired appliances, including the steps of: using the solenoid valve to block fuel gas, determining whether the power returns to normal, and if not, maintaining the solenoid valve block, and if so, closing the flow-regulating valve to thereby block the fuel gas such that the fuel gas flow is paused when the solenoid valve is open during a next ignition try.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to control supply of fuel gas, and more particularly to a method for controlling fuel gas flow to a gas-fired appliance during power surges or outages. 
         [0003]    2. Description of Related Art 
         [0004]    A gas-fired appliance heats objects with flame generated by burning combustible gas. A traditional gas-fired appliance comprises a combustor and a manual regulating valve, wherein the combustor burns fuel gas, and the manual regulating valve can be used to manually adjust the flow of fuel gas supplied to the combustor. For precise flow control, an advanced gas-fired appliance uses a proportional valve instead of the manual regulating valve to control the flow. Particularly, the flow of the fuel gas is precisely controlled by adjusting the current passing through the coil of the proportional valve. 
         [0005]    While such a proportional valve may provide precise flow control, it requires continuous power supply to the coil even for constant flow output only, which increases power consumption. For this problem, a solution has been proposed that uses a motor-controlled flow-regulating valve together with a solenoid valve to replace the foregoing proportional valve, wherein a controller controls the motor of the flow-regulating valve to drive a valve plug to close the valve opening of the flow-regulating valve as required, so as to change the flow, and the solenoid valve serves to allow or disallow the fuel gas to pass the valve. Whereby, after the fuel gas output by the flow-regulating valve is adjusted to a desired flow, even if the motor is unpowered, the constant flow can still be maintained. In addition, since the solenoid valve consumes less power than the proportional valve does, the benefit of saving energy can be achieved. 
         [0006]    When the power supplied to the gas-fired appliance is cut off, the controller loses the power and is not able to control the motor, so the valve opening of the flow-regulating valve remains open. At this time, the solenoid valve stops the fuel gas, so as to prevent more supply of the fuel gas to the combustor. However, after power restoration, the controller has no way to know how much the valve opening of the flow-regulating valve is open, which increases the difficulty of subsequent control. In addition, after power restoration, the fuel gas will immediately arrive at the combustor as soon as the solenoid valve is open, and may dangerously leak out if the fire is not immediately ignited. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The primary objective of the present invention is to provide a method for controlling a gas-fired appliance, which featuring closing the valve opening of a flow-regulating valve after power restoration. 
         [0008]    To achieve the objective of the present invention, the present invention discloses the method for controlling a gas-fired appliance, which includes a combustor, at least one flow-regulating valve and a solenoid valve, wherein the at least one flow-regulating valve and the solenoid valve are installed on a pipeline that communicates with the combustor and serves to introduce fuel gas; each of the at least one flow-regulating valve has a valve body, a valve plug, and a motor, wherein the valve body has a valve opening for the fuel gas to pass therethrough, and the valve plug is driven by the motor to change a degree of openness of the valve opening; the solenoid valve is controllable to allow or disallow the fuel gas to pass therethrough; the gas-fired appliance further includes a power source for powering the motor. The disclosed method for controlling the gas-fired appliance is to be performed after the power source stops supplying power, and comprises the steps of: A. using the solenoid valve to block the fuel gas from passing therethrough; and B. when the power source starts to supply the power again, controlling the motor to make the valve plug close the valve opening. 
         [0009]    The present invention further provides a method for controlling a gas-fired appliance, which includes a combustor, at least one flow-regulating valve, and a solenoid valve, wherein the at least one flow-regulating valve and the solenoid valve are installed on a pipeline that communicates with the combustor and serves to introduce fuel gas; each of the at least one flow-regulating valve has a valve opening, a valve plug, and a motor, wherein the valve opening allows the fuel gas to pass therethrough, and the valve plug is driven by the motor to change a degree of openness of the valve opening; the solenoid valve is controllable to allow or disallow the fuel gas to pass therethrough; the gas-fired appliance further includes a power source for powering the motor. the disclosed method for controlling the gas-fired appliance comprises the steps of: A. when power supplied by the power source is below a predetermined voltage, making the solenoid valve block the fuel gas from passing therethrough; B. determining whether the power supplied by the power source becomes higher than the predetermined voltage again, and if so, controlling the motor to make the valve plug close the valve opening; if not so, keeping making the solenoid valve block the fuel gas from passing therethrough; and C. repeating Step B until the valve plug closes the valve opening. 
         [0010]    A benefit of the present invention is that when the power provided by the power source resumes following power surges or outages when the supply falls below a predetermined minimum voltage, it is ensured that the flow-regulating valve well blocks the fuel gas, so that when the solenoid valve is open during a next ignition try, the fuel gas is prevented from flowing to the combustor immediately. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]    The structure as well as a preferred mode of use, further objects, and advantages of the present invention will be best understood by referring to the following detailed description of some illustrative embodiments in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a schematic drawing showing the gas-fired appliance according to a first preferred embodiment of the present invention; 
           [0013]      FIG. 2  is a schematic drawing showing the flow-regulating valve according to the first preferred embodiment of the present invention; 
           [0014]      FIG. 3  is a flowchart of the method according to the first preferred embodiment of the present invention; 
           [0015]      FIG. 4  is a flowchart of the method according to a second preferred embodiment of the present invention; and 
           [0016]      FIG. 5  is a schematic drawing showing the gas-fired appliance according to a third preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    The present invention is best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings clarifying its modes of use, as well as, objectives and advantages. 
         [0018]      FIG. 1  is a schematic drawing showing a gas-fired appliance according to a first preferred embodiment of the present invention. In the present embodiment, the gas-fired appliance is a gas stove  1 , which comprises a combustor  10 , a flow-regulating valve  12 , a pressure regulator  14 , a blower  16 , and a controller  18  all contained in a housing. 
         [0019]    The combustor  10  communicates with a pipeline P, and is used to burn fuel gas, such as natural gas, to generate flame. As shown in  FIG. 2 , the flow-regulating valve  12  has a valve body  122  and a step motor  124 . The valve body  122  is installed in the route of the pipeline P. The valve body  122  has a valve opening  122   a  that allows fuel gas to pass therethrough. The step motor  124  has its rotating shaft  124   a  connected to a valve plug  128  through a connecting mechanism  126 . The step motor  124  receives pulse signals to drive the valve plug  128  to shift in the valve opening  122   a , so as to change a degree of openness of the valve opening  122   a , thereby adjusting the flow of the fuel gas. The step motor  124  receives a predetermined number of pulse signals, so as to drive the valve plug  128  to make the degree of openness of the valve opening  122   a  change from where the valve opening  122   a  is fully open to where the valve opening  122   a  is closed. 
         [0020]    The pressure regulator  14  is also installed in the route of the pipeline P. The pressure regulator  14  has a regulating valve  142  and a solenoid valve  144  that are mutually connected. The regulating valve  142  serves to lower the pressure of the fuel gas and to output the fuel gas to the solenoid valve  144 . The solenoid valve  144  is a normally closed solenoid valve. When receiving a high-level electric signal, the solenoid valve  144  is opened to allow the fuel gas to pass therethrough. When not receiving the electric signal, the solenoid valve  144  automatically blocks the fuel gas. 
         [0021]    The blower  16  communicates with the combustor  10 , and is controllable to change the rotational speed of its motor, so as to change the air volume it sends into the combustor  10 . 
         [0022]    The controller  18  is electrically connected to a control panel  20  and an ignition sensor pin  22 , wherein the controller  18  is electrically connected to the step motor  124 , the solenoid valve  144 , and the blower  16  as well. The control panel  20  is for a user to operate so as to activate functions such as ignition, firepower adjustment and turning off fire. The controller  18  is electrically connected to a power source  24 . The power source  24  powers the controller  18 , and the power source  24  also powers the control panel  20 , the ignition sensor pin  22 , the step motor  124 , the solenoid valve  144 , and the blower  16 . In the present embodiment, the power source  24  is a battery. In other embodiments, it may be a transformer that converts an alternating current to a direct current. 
         [0023]    When the user chooses to ignite through the control panel  20 , the controller  18  controls the ignition sensor pin  22  to generate a spark, and to keep sending the electric signal to the solenoid valve  144 , so as to keep the solenoid valve  144  open. Then, the controller  18  controls the step motor of the flow-regulating valve  12  to make the valve plug  128  open the valve opening  122   a , thereby allowing the fuel gas to enter the combustor  10  and generate flame. The blower  16  is also controlled to supply a proper volume of air to the combustor  10 . The controller  18  then uses the ignition sensor pin  22  to sense whether the flame is present. If the flame exists, the spark-making operation is stopped. If the flame goes out, the controller  18  stops outputting the electric signal so as to make the solenoid valve  144  block the fuel gas. 
         [0024]    When the user chooses firepower adjustment, the controller  18  controls the step motor  124  to change the degree of openness of the valve opening  122   a , so as to increase or decrease the flow of the fuel gas supplied to the combustor  10 . At the same time, the controller  18  controls the blower  16  correspondingly, so as to supply a proper volume of air to the combustor  10  and support good combustion. 
         [0025]    When the user chooses to turn off the fire, the controller  18  stops outputting the electric signal to the solenoid valve  144 , so as to cut off the supply of the fuel gas, and the controller  18  controls the step motor to close the valve opening  122   a . At last, the blower  16  is stopped. 
         [0026]    During combustion of the fuel gas, whenever the power source fails, the method shown in  FIG. 3  is performed as below. 
         [0027]    First, since the power source  24  no more supplies power, the controller  18  can&#39;t output the electric signal to the solenoid valve  144  anymore. Therefore, the solenoid valve  144  automatically blocks the fuel gas, and this prevents the fuel gas from keeping flowing and leaking out. 
         [0028]    When the power supply of the power source  24  resumes, the controller  18  is reactivated and then sends at least the predetermined number of pulse signals to the step motor  124 , so as to ensure that the valve plug  128  moves to a position where the valve opening  122   a  is closed. Afterward, the appliance is in a standby state and ready for the user to make ignition. 
         [0029]    Thereby, the fuel gas is prevented from immediately enter the combustor  10  when ignition is made and the solenoid valve  144  is open after power restoration. Additionally, since the controller  18  closes the valve opening  122   a  when reactivated, the valve opening  122   a  is set into its initial state. Thus, during every first ignition after power restoration, the controller  18  can make the valve opening  122   a  remain the same level of openness by sending a constant number of said pulse signals to the step motor  124 , so to achieve more convenient control after power restoration. 
         [0030]      FIG. 4  is a flowchart of a method according to a second preferred embodiment of the present invention. In the present embodiment, the method uses a gas stove similar to that described in the first embodiment. Different from the first embodiment, the controller  18  herein further has a voltage detecting unit (not shown). The voltage detecting unit serves to detect the voltage of the power source  24 . The controller  18  is programmed with a predetermined voltage. The predetermined voltage is the minimum voltage that is required to drive the motor  124 . 
         [0031]    In the present embodiment, the method is to be performed when the combustor  10  burns the fuel gas. 
         [0032]    When the voltage from the power source  24  is below the predetermined voltage, the controller  18  stops sending the electric signal to the solenoid valve  144 , so as to make the solenoid valve  144  blocks the fuel gas. 
         [0033]    Afterward, the controller  18  determines whether the power from the power source  24  becomes higher than the predetermined voltage from the previous state where it is below the predetermined voltage. 
         [0034]    If it is the case, the controller  18  sends at least the predetermined number of pulse signals to the step motor  124 , so as to keep the valve plug  128  closing the valve opening  122   a.    
         [0035]    If it is not the case, the solenoid valve  144  keeps blocking the fuel gas. 
         [0036]    The previous step will be repeated until the power from the power source  24  becomes higher than the predetermined voltage again. At this time, the valve opening  122   a  is closed and the appliance is in a standby state where it is ready for the user to ignite fire. 
         [0037]    In this manner, it is possible to stop the supply of the fuel gas when the power from the power source  24  is too low to activate the step motor  124 , and to close the valve opening  122   a  when the power from the power source  24  becomes higher than the predetermined voltage again. 
         [0038]      FIG. 5  schematically depicts a gas-fired appliance according to a third preferred embodiment of the present invention. In the third preferred embodiment, the gas-fired appliance is a gas roaster  2 , which is basically the same with the gas stove  1  mentioned in the first embodiment, except that the gas roaster  2  has two combustors  30 , two flow-regulating valves  32 , a pressure regulator  34 , and a controller  36 . 
         [0039]    The two combustors  30  communicate with the two flow-regulating valves  32 , respectively. The two flow-regulating valves  32  are connected to the pressure regulator  34  through a pipeline P. The controller  36  is electrically connected to two control panels  38 , two ignition sensor pins  40 , step motors  322  of the flow-regulating valves  32 , and a solenoid valve  342  of the pressure regulator  34 . 
         [0040]    The gas roaster  2  is provided with a power source  42  for powering the controller  36 , the control panel  38 , the ignition sensor pin  40 , the step motors  322 , and the solenoid valve  342 . 
         [0041]    By operating the control panels  38 , a user can individually control ignition, firepower adjustment and turning off fire of the combustors  30 . When the user ignites fire on one of the combustors  30 , the controller  36  opens the solenoid valve  342 , and makes the corresponding flow-regulating valve  32  to open its valve opening. Then when the user ignites fire on the other combustor  30 , the corresponding flow-regulating valve  32  is controlled to open its valve opening. 
         [0042]    The method of the present embodiment is to be performed when the power supplied by the power source  42  is cut off. It includes steps similar to those of the first embodiment, except that after the power of the power source  42  resumes, the controller  36  sends at least the predetermined number of pulse signals to the two step motors  322 , respectively, so as to ensure that the valve plug of each of the flow-regulating valves  32  moves to close its valve opening. 
         [0043]    Since the two flow-regulating valves  32  are connected to the same pressure regulator  34 , the method of the present embodiment can ensure that during a standby state after power restoration, the valve openings of the two flow-regulating valves  32  are both closed. Thus, when one of the combustors  30  is operated for ignition, the fuel gas is prevented from leaking out from the other combustor  30 . 
         [0044]    The gas roaster  2  of the third embodiment can be used to implement a method according to a fourth embodiment of the present invention. The method of the fourth embodiment is similar to that of the second embodiment for that its controller  36  also has a voltage detecting unit and is programmed with a predetermined voltage, but has the following differences. 
         [0045]    When the controller  36  determines that the power from the power source  42  becomes higher than the predetermined voltage from the previous state where it is below the predetermined voltage, the controller  36  sends at least the predetermined number of pulse signals to the two step motors  322 , respectively, so as to close the valve openings of the flow-regulating valves  32 . In this manner, it is possible to ensure when the power from the power source  42  becomes higher than the predetermined voltage again and the appliance enters its standby state, the valve openings of the two flow-regulating valves  32  are both closed. When one of the combustors  30  is operated for ignition, the fuel gas is prevented from leaking out from the other combustor  30 . 
         [0046]    While the previous embodiments are described against gas-fired appliances that fire natural gas, the present invention is not limited thereto. In other embodiments, gas-fired appliances firing other combustible gases such as hydrogen or acetylene may be also employed to be applied with the present invention. 
         [0047]    In summary, the disclosed method for controlling a gas-fired appliance ensures that when the power from power source becomes normal after power failure or low power, the valve opening is closed so as to facilitate subsequent controls. Besides, when the solenoid valve is open during next ignition, the fuel gas is prevent from flowing into the combustor immediately. 
         [0048]    The present invention has been described with reference to the preferred embodiments and it is understood that the embodiments are not intended to limit the scope of the present invention. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the concept of the present invention should be encompassed by the appended claims.