WO2022006213A1 - Cooktop gas safety valve hold open circuit with ceramic heater - Google Patents
Cooktop gas safety valve hold open circuit with ceramic heater Download PDFInfo
- Publication number
- WO2022006213A1 WO2022006213A1 PCT/US2021/039785 US2021039785W WO2022006213A1 WO 2022006213 A1 WO2022006213 A1 WO 2022006213A1 US 2021039785 W US2021039785 W US 2021039785W WO 2022006213 A1 WO2022006213 A1 WO 2022006213A1
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- WIPO (PCT)
- Prior art keywords
- igniter
- coil
- cooking gas
- gas safety
- hold
- Prior art date
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
- F23N5/10—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples
- F23N5/107—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples using mechanical means, e.g. safety valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
- F24C3/00—Stoves or ranges for gaseous fuels
- F24C3/12—Arrangement or mounting of control or safety devices
- F24C3/126—Arrangement or mounting of control or safety devices on ranges
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N1/00—Regulating fuel supply
- F23N1/005—Regulating fuel supply using electrical or electromechanical means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N5/00—Systems for controlling combustion
- F23N5/20—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays
- F23N5/203—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23Q—IGNITION; EXTINGUISHING-DEVICES
- F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
- F23Q7/06—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs structurally associated with fluid-fuel burners
- F23Q7/10—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs structurally associated with fluid-fuel burners for gaseous fuel, e.g. in welding appliances
- F23Q7/12—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs structurally associated with fluid-fuel burners for gaseous fuel, e.g. in welding appliances actuated by gas-controlling device
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23Q—IGNITION; EXTINGUISHING-DEVICES
- F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
- F23Q7/22—Details
- F23Q7/24—Safety arrangements
- F23Q7/26—Provision for re-ignition
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23K—FEEDING FUEL TO COMBUSTION APPARATUS
- F23K2900/00—Special features of, or arrangements for fuel supplies
- F23K2900/05002—Valves for gaseous fuel supply lines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/28—Ignition circuits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/32—Igniting for a predetermined number of cycles
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2227/00—Ignition or checking
- F23N2227/42—Ceramic glow ignition
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/06—Fail safe for flame failures
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2235/00—Valves, nozzles or pumps
- F23N2235/12—Fuel valves
- F23N2235/14—Fuel valves electromagnetically operated
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2235/00—Valves, nozzles or pumps
- F23N2235/12—Fuel valves
- F23N2235/16—Fuel valves variable flow or proportional valves
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2235/00—Valves, nozzles or pumps
- F23N2235/12—Fuel valves
- F23N2235/22—Fuel valves cooperating with magnets
Definitions
- This disclosure relates to gas safety valves with a hold open circuit that holds the valve open when a threshold current sufficient to heat a hot surface igniter to an autoignition temperature of the gas is reached.
- Certain cooktops include safety features to ensure that cooking gas is only supplied to the burner once ignition is achieved. This ensures that uncombusted cooking gas is not supplied to the surrounding environment, which could lead to a fire or explosion.
- the integrated gas valve and electromagnet is referred to as a “gas tap” in Europe.
- hot surface igniters can be continuously energized to ignite cooking gas because it is the igniter surface temperature, and not a discrete burst of electric potential, that causes ignition.
- the energization state of the hot surface igniter provides an indication that ignition has occurred (or will occur) which allows for the elimination of the thermocouple.
- some means is required to link the current used to energize the igniter to the current required to hold the gas valve open.
- a cooking gas safety apparatus comprising a valve assembly comprising a valve and at least one coil.
- the valve comprises a fluid inlet and a fluid outlet and is manually operable to place the fluid inlet in fluid communication with the fluid outlet, wherein the at least one coil is energizable to hold the valve in the open position only when subjected to a current that exceeds a threshold current value; and the apparatus further comprises a hot surface igniter electrically connectable to the at least one coil to define a hold-open circuit, and wherein when subjected to an alternating current of 120 V AC rms, the hot surface igniter reaches a surface temperature of at least 1400°F in no more than eight seconds after the at least one coil is subjected to the threshold current.
- FIG. 2 is a cross-sectional view of the gas safety valve assembly of FIG. 1 in an open position.
- FIG. 3 is a cross-sectional view of the gas safety valve assembly of FIG. 1 in the open position of FIG. 2 in which a tapered sleeve with a metering orifice has been removed;
- FIG. 6 is a template circuit configured to energize a hot surface igniter to two different energization states and which may be provided with a number of different circuit components useful for providing various indications of the state of a burner and controlling its operation;
- FIG. 7 is the template circuit of FIG. 6 modified to hold open a gas safety valve assembly comprising a direct current coil for holding the valve assembly open;
- FIG. 8 is an example of a hold-open circuit comprising a hot surface igniter and an alternating current coil for holding open a gas safety valve assembly;
- FIG. 9 is a illustrative depiction of voltage versus time for the capacitor input voltages in the hold-open circuit of FIG. 4 superimposed on the diode output voltage for the hold-open circuit;
- FIG. 10B is a graph depicting simulation current versus time data for the hot surface igniter in the hold-open circuit of FIG. 4 when operating at full power;
- FIG. 11 A is a graph depicting simulation voltage versus time data for the input voltage to the hot surface igniter in the hold-open circuit of FIG. 4 when operating at reduced power;
- FIG. 1 ID is a graph depicting simulation current versus time data for the direct current coil in the hold-open circuit of FIG. 4 when operating at reduced power;
- FIG. 12B is a graph depicting simulation current versus time data for the hot surface igniter in the hold-open circuit of FIG. 5 when operating at full power;
- FIG. 13 A is a graph depicting simulation voltage versus time data for the input voltage to the hot surface igniter in the hold-open circuit of FIG. 5 when operating at reduced power;
- FIG.13B is a graph depicting simulation current versus time data for the hot surface igniter in the hold-open circuit of FIG. 5 when operating at reduced power;
- FIG. 16B is a graph depicting simulation current versus time data for the input current to the hot surface igniters in the hold-open circuit of FIG. 14 and the hold-open circuit of FIG. 15 when it is operating at full power;
- FIG. 16D is a graph depicting simulation current versus time data for the direct current coil in the hold-open circuit of FIG. 14 and the hold-open circuit of FIG. 15 when it is operating at full power;
- FIG. 17A is a graph depicting simulation voltage versus time data for the input voltage to the hot surface igniter in the hold-open circuit of FIG. 15 when operating at reduced power;
- FIG. 17B is a graph depicting simulation current versus time data for the hot surface igniter in the hold-open circuit of FIG. 15 when operating at reduced power
- FIG. 17C is a graph depicting simulation voltage versus time data for the input voltage to the resistor in the hold-open circuit of FIG. 15 when operating at reduced power
- the hold open circuit causes the valve to close if a hot surface igniter used to ignite the burner is not energized sufficiently to reach (or maintain) a surface temperature at or above the autoignition temperature of the cooking gas, thereby reducing the likelihood that gas will unintentionally flow to an unlit burner.
- the igniter is energized by a source of alternating current
- the at least one coil is a direct current coil that only holds the valve open when subjected to a threshold direct current.
- the hold open circuit is configured to supply the threshold direct current to the at least one coil only when the igniter is supplied with a current sufficient to cause a surface of the igniter to reach an autoignition temperature of the cooking gas.
- a tapered sleeve 28 with an inlet metering orifice 29 is provided and includes an outlet 31 through which gas may pass when a valve disk 36 is unseated (FIG. 2) from a shoulder 45 of an axial fluid passage 43. Not all of orifice 29 is visible in FIGS. 1 and 2, but gas inlet 22 is in fluid communication with orifice 29.
- a shaft engagement surface 38 is provided on the valve disk 36 and is engaged by a shaft 44 (FIG. 2) that runs through the tapered sleeve 28 along the lengthwise (/) axis of the gas safety valve assembly 20.
- Shaft 44 is operatively connected to a gas knob stem 26 (the knob is removed in the figures) that is axially depressible in the distal direction along the lengthwise (/) axis of the cooking gas safety valve assembly 20. Depressing the gas knob stem 26 axially in the distal direction causes the shaft 44 to move the valve disk 36 distally along the lengthwise (I) axis and out of engagement with axial fluid passage 43 shoulder 45.
- the shaft 44 has a diameter along the radial axis r that is narrower than the diameter of the axial fluid passage 43 at shoulder 45, and distally of the shoulder 45.
- the fluid passage 43 has a diameter along the radial axis r that is larger than the diameter of the open area defined radially within shoulder 45.
- the valve disk 36 is connected to a distal valve shaft 32 which is in turn connected to a magnetic disk 30 that is housed in electromagnet housing 41.
- Electromagnet housing 41 houses a direct current coil 40 wrapped around a corresponding magnetic core 42. Multiple coils each wrapped around their own respective core may also be provided.
- the valve disk 36 is biased in the proximal direction along the length / axis by spring 34 which is attached to the proximal end of electromagnet housing 41.
- the distal valve shaft 32 runs through the spring 34 and through a hole (not shown) in the proximal end of the electromagnet housing 41.
- valve disk 36 is biased away from electromagnet housing 41 by biasing spring 34 and into engagement with shoulder 45 of axial fluid passage 43.
- the distal end 47 of shaft 44 engages the shaft engagement surface 38 of valve disk 36 and displaces the valve disk 36 in the distal direction along the length / axis to the open position of FIG. 2.
- the displacement of the valve disk 36 along the length / axis also displaces distal valve shaft 32 in the distal direction along the length / axis, thereby causing the magnetic disk 30 to be distally displaced into engagement with the magnetic core 42.
- the direct current coil 40 When a threshold current is provided to the direct current coil 40, the resulting magnetic force will hold the valve’s 21 magnetic disk 30 into engagement with the magnetic core 42 even if the user releases the gas knob stem 26. Without the magnetic force, releasing the gas knob stem 26 would cause the biasing force of spring 34 to urge valve disk 36 in the proximal direction along the length / axis and into engagement with the axial fluid passage channel shoulder 45, which in turn would cause shaft engagement surface 38 to urge shaft 44 in the proximal direction along the length / axis. As long as the direct current through the coil 40 remains above the threshold current characteristic of the gas safety valve assembly 20, the magnetic force will hold the valve’s magnetic disk 30 into engagement with the magnetic core 42, thereby keeping the valve 21 in the open position of FIG. 2.
- the magnetic field generated by direct current coil 40 is strong enough to hold magnetic disk 30 into engagement with magnetic core 42 but is not strong enough to pull the magnetic disk 30 into engagement with magnetic core 42.
- the flame detection scheme typically uses a thermocouple to generate a direct current for the coil 40 when a flame is present.
- Ceramic hot surface igniters useful in connection with the gas valve assemblies described herein include those described in U.S. Patent Application No. 16/366,479, the entirety of which is hereby incorporated by reference.
- the preferred ceramic hot surface igniters 52 described herein are generally in the shape of a rectangular cube and include two major facets, two minor facets, a top and a bottom.
- the major facets are defined by the first (length) and second (width) longest dimensions of the ceramic hot surface igniter body.
- the minor facets are defined by the first (length) and third (thickness) longest dimensions of the igniter body.
- the igniter bodies also include a top surface and a bottom surface which are defined by the second (width) and third (thickness) longest dimensions of the igniter body.
- the ceramic hot surface igniter 52 may have a positive or negative temperature coefficient of resistance. However, positive temperature coefficients of resistance are preferred.
- the igniter tiles are ceramic and preferably comprise silicon nitride.
- the conductive ink circuit is disposed between the tiles and generates heat when energized.
- the ceramic tiles are electrically insulating but sufficiently thermally conductive to reach the outer surface temperature necessary to ignite combustible mixtures of air and gases selected from natural gas, propane, butane, butane 1400 (a butane and air mixture with a heating value of 1400 Btu/ft 3 ), and mixtures thereof, within the desired period of time.
- the ceramic hot surface igniters 52 described herein when subjected to a potential difference of 120V AC (rms), reach a surface temperature of at least 1400°F, preferably no less than 1800°F, more preferably no less than 2100°F, and even more preferably no less than 2130°F. These temperatures are preferably reached in no more than eight seconds, more preferably reached in no more than six seconds, and still more preferably, reached in no more than four seconds after the 120V AC (rms) potential difference is applied.
- the surface temperature of the ceramic hot surface igniters herein does not exceed 2600°F, preferably does not exceed 2550°F, more preferably does not exceed 2500°F, and still more preferably 2450°F at any time after a full wave 132V AC (rms) potential difference is applied to the igniter, including after a steady-state temperature is reached.
- the ceramic hot surface igniters described herein when subjected to a potential difference of 102V AC (rms), reach a surface temperature of at least 1400°F, preferably at least 1800°F, and still more preferably at least 2100°F in no more than seventeen, preferably more than ten, and more preferably no more than about seven seconds after the 102V AC (rms) potential difference is first applied. These temperatures are preferably reached in no more than four seconds and are more preferably reached in no more than three seconds.
- ceramic hot surface igniters 52 used in the gas heating systems described herein are prepared by sintering ceramic compositions.
- the tiles used to form the igniter 52 (not including conductive ink circuit) have a room temperature resistivity that is no less than 10 12 W-cm, preferably no less than 10 13 W-cm, and more preferably, no less than 10 14 W-cm.
- the tiles have a thermal shock value in accordance with ASTM C-1525 of no less than 900°F, preferably no less than 950°F, and more preferably, no less than 1000°F.
- the conductive ink comprising the conductive ink circuit has a (post-sintering) room temperature resistivity of from about 1.4xl0 4 W-crn to about 4.5xl0 4 W-crn, preferably from about 1.8xl0 4 W-crn to about 4. lx 10 4 W-crn, and more preferably from about 2.2xl0 4 W-crn to about 3.7xl0 4 W-crn.
- resistivity p at a given temperature T is related to resistance R at the same temperature T in accordance with the well-known formula:
- R Resistance in ohms (W) at temperature ;
- T Temperature (°F or °C);
- A cross-sectional area (cm 2 ) of conductive ink circuit perpendicular to the direction of current flow;
- the ceramic bodies comprising the ceramic hot surface igniters 52 herein preferably comprise silicon nitride and a rare earth oxide sintering aid, wherein the rare earth element is one or more of ytterbium, yttrium, scandium, and lanthanum.
- the sintering aids may be provided as co-dopants selected from the foregoing rare earth oxides and one or more of silica, alumina, and magnesia.
- a sintering aid protective agent is also preferably included which also enhances densification.
- a preferred sintering aid protective agent is molybdenum disilicide.
- the rare earth oxide sintering aid (with or without the co-dopant) is preferably present in an amount ranging from about 2 to about 15 percent by weight , more preferably from about 8 to about 14 percent by weight, and still more preferably from about 12 to about 14 percent by weight of the ceramic body.
- Molybdenum disilicide is preferably present in an amount ranging from about 3 to about 7 percent, more preferably from about 4 to about 7 percent, and still more preferably from about 5.5 to about 6.5 percent by weight of the ceramic body.
- the balance is silicon nitride.
- the conductive ink circuit is preferably printed onto the face of one of the ceramic tiles to yield a ceramic hot surface igniter(post-sintering) room temperature resistance (RTR) of from about 60 W to about 120 W, preferably from about 70 W to about 110 W , and more preferably from about 80 W to about 100 W.
- RTR room temperature resistance
- the ceramic hot surface igniter high temperature resistance (HTR) over the temperature range 2138°F to 2700°F is generally from about 300W to about 500W, preferably from about 400W to about 480W, and more preferably from about 430W to about 450W.
- the conductive ink in the igniter 52 should comprise tungsten carbide in an amount ranging from about 20 to about 80 percent, preferably from about 30 percent to about 80 percent, and more preferably from about 70 to about 75 percent by weight of the ink.
- Silicon nitride is preferably provided in an amount ranging from about 15 to about 40 percent, preferably from about 15 to about 30 percent, and more preferably from about 18 to about 25 percent by weight of the ink.
- the same sintering aids or co-dopants described for the ceramic body are also preferably included in an amount ranging from about 0.02 to about 6 percent, preferably from about 1 to about 5 percent, and more preferably from about 2 to about 4 percent by weight of the ink.
- the valve assembly 20 is manually actuatable to an open position (FIG. 2) using gas knob stem 26 as described previously.
- the direct current coil 40 is energized to a current that exceeds a threshold direct current while the valve disk 36 is in the open position of FIG. 2, the magnetic force of the direct current coil 40 holds the valve disk 36 open by holding magnetic disk 30 into engagement with magnetic core 42 without the need for the user to continue to depress gas knob stem 26.
- the threshold direct current is the RMS value of the time-varying current.
- the hold open circuit 50 includes hot surface igniter 52 and direct current coil 40.
- the hot surface igniter 52 is in electrical communication with the direct current coil 40 such that when the direct current coil 40 is subjected to a current having the threshold current value, a surface of the igniter 52 reaches at least an autoignition temperature of the cooking gas. Providing an igniter 52 that only reaches the gas autoignition temperature when the direct current coil 40 is at or below threshold current better ensures that gas is shut-off to the burner when the igniter is not hot enough to ignite the cooking gas.
- thermocouples which have significant dead time or lag time may be eliminated, which significantly reduces the amount of time during which the user must depress the gas knob stem 26 in the distal direction along the length / axis to keep the gas valve assembly in the open condition (of FIG. 2).
- the hot surface igniter 52 is powered by an alternating current source 51.
- the alternating current supplied by alternating current source 51 to direct current coil 40 is converted to a time-varying direct current.
- direct current refers to a current having one polarity.
- a “direct current” may have a constant or time-varying value as long as it has one polarity.
- the hold-open circuit 50 is configured to store electric potential when the alternating current source cycle is one polarity and to make the electric potential available for use by the direct current coil 40 when the alternating current source cycle is the opposite polarity.
- another switch would be provided to selectively energize the hold-open circuit 50 in response to the depression of gas knob stem 26 in the distal direction along the length / axis (FIG. 2).
- the alternating current source 51 is in selective electrical communication with the hot surface igniter 52 and the direct current coil 40.
- the hot surface igniter 52 is in a series-parallel combination with the direct current coil 40.
- series-parallel and parallel- series refer to components that are not strictly in a series or parallel relationship with one another.
- the term “series” as used to describe the relationship between two components of an electrical circuit means one current flows in turn through each of the components.
- parallel as used to describe the relationship between two components of an electrical circuit means that the current divides between the components and then later reunites. Referring to FIG. 4, a portion of the current flowing through igniter 52 will flow through the direct current coil 40, another portion of the current flowing through igniter 52 will flow through resistor 56, and the two currents will re-unite.
- the alternating current supplied to the hot surface igniter 52 is rectified, and preferably half-wave rectified.
- diodes allow current of only one polarity to flow.
- Diode 64 is in a series-parallel combination with hot surface igniter 52 as a portion of the current flowing through diode 64 during the portion of the AC cycle in which the diode is forward biased will also flow through the hot surface igniter 52.
- Diode 64 is not placed directly in series with hot surface igniter 52 because the current flowing from diode 64 to igniter 52 would drop to zero during each half AC cycle, causing the direct current coil 40 to release the valve disk 36 to the closed position of FIG. 1 when the current crosses the zero pole.
- capacitors are provided which charge when diode 64 is forward-biased and discharge when diode 64 is reverse-biased.
- the diode 64 voltage and current rating are preferably selected to balance cost with the circuit 50 lifetime as lower voltage or current ratings will tend to decrease the lifetime of circuit 50.
- the respective RMS current or voltage value is the DC value that has an effect equivalent to the time-varying value.
- Tl time value (seconds) at the beginning of a period
- T2 time value (seconds) at the end of the period beginning at Tl.
- Vrms is the root-mean-square voltage (volts) of the function v(t)
- T2 time value (seconds) at the end of the period beginning at Tl; and irms is the root-mean-square voltage (volts) of the function i (t)
- Capacitor 58 and 60 help to smooth the direct current ripple voltage and increase the root mean square (RMS) voltage seen by the igniter 52 and the direct current coil 40 after rectification.
- Capacitor 60 is in selective electrical communication with hot surface igniter 52 and direct current coil 40.
- Switch 62 is in series with capacitor 60. When switch 62 is open, capacitor 60 is disconnected from the hold open circuit 50 and is not in electrical communication with either hot surface igniter 52 or direct current coil 40, i.e., only capacitor 58 reduces the ripple factor.
- switch 62 is closed and in contact with pole 63, capacitor 60 is in electrical communication with both hot surface igniter 52 and direct current coil 40.
- FIG. 9 depicts how capacitor 58 alone or in parallel with capacitor 60 (when switch 62 is closed) smooths the ripple voltage produced by diode 64.
- the rectified waveform in FIG. 9 is the output voltage signal from diode 64, which is also the input voltage to hot surface igniter 52 and at node N52.
- capacitor 58 is charging (as is capacitor 60 if switch 62 is closed) until it reaches its saturation voltage or until the AC source reaches its peak voltage.
- the hot surface igniter 52 input voltage tracks the AC wave form from AC source 51. As the AC source reaches its peak voltage and begins to fall below the capacitor 58 saturation voltage, capacitor 58 begins to discharge and supplies current to hot surface igniter 52 as indicated by the upper line segments in FIG. 9. Once the capacitor 58 voltage drops below the AC source voltage, capacitor 58 again begins to charge. As a result, hot surface igniter 52 sees the voltage represented by the upper graph in FIG. 9 instead of seeing the rectified voltage output from diode 64, thereby smoothing the ripple of the rectified wave form.
- the resulting voltages and currents seen by the hot surface igniter 52 and the direct current coil 40 are time-varying direct current voltages and currents, which enable the direct current coil 40 to hold the valve disk 36 (FIG. 2) open despite the AC source reversing polarity every half cycle.
- the total capacitance of circuit 50 increases, it “smooths” or dampens the ripple.
- switch 62 When switch 62 is closed, the total capacitance is the sum of the capacitances of capacitor 58 and capacitor 60.
- switch 62 When switch 62 is open, the total capacitance is the capacitance of capacitor 58.
- Equation (2c) shows that as the total capacitance Ctotai increases, the spread (AV) between the maximum and minimum voltages seen by hot surface igniter 52 decreases:
- circuit 50 when circuit 50 is in reduced power mode, as the capacitance of capacitor 60 decreases, the igniter 52 input voltage at node N52 will show more ripple (become “less flat”), and the RMS current through igniter 52 will decrease, causing igniter 52 to reach a lower steady-state temperature.
- the direct current coil 40 tends to have a much lower resistance and inductance than the other circuit components. Thus, the selection of those properties for the coil 40 tends to be less critical to the overall performance of circuit 50.
- switch 62 When switch 62 is closed, the hot surface igniter 52 is in full-power mode. When switch 62 is open, hot surface igniter 52 is in reduced power mode. Full power mode is preferably used during an ignition operation.
- Reduced power mode is preferably used during a cooking operation and provides a means of reigniting the cooking gas in the event of a flame out.
- capacitors 58 and 60 act as a single capacitor having a total capacitance that equals the sum of each of their respective capacitances, meaning that the parallel combination is equivalent to a single capacitor having a capacitance equal to the sum of both capacitances.
- the capacitance values of capacitors 58 and 60 will affect the percentage of full power that is achieved during reduced power operation. In certain examples, releasing the gas valve stem 26 after the direct current coil 40 has latched in the open position of FIG. 2 will cause switch 62 to open and place circuit 50 in a reduced power mode.
- the power provided to igniter 52 in the reduced power mode is from about 70 percent to about 90 percent, preferably from about 75 percent to about 85 percent, and more preferably from about 78 percent to about 82 percent of the power provided to igniter 52 in a full power mode.
- the hot surface igniter 52 is not directly in series with the direct current coil 40 because the threshold current required to hold the valve assembly 20 open is less than the hot surface igniter 52 current required for the igniter surface to reach the autoignition temperature of the cooking gas.
- Resistor 56 is a shunt resistor that makes circuit 50 more sensitive and more responsive by shunting current away from direct current coil 40, which causes direct current coil 40 to shut off- and valve 21 to close — at a higher current than would otherwise be required in the absence of resistor 56.
- the igniter 52 may receive significantly more current than the threshold current for direct current coil 40 to magnetically hold open the valve assembly 20 (FIGS. 1-3).
- the resistance of shunt resistor 56 may be selected to provide a margin of safety between the igniter 52 current at which the igniter 52 reaches the cooking gas autoignition temperature and the trigger current at which the direct current coil 40 holds open the valve 21.
- Resistor 54 is provided to provide an additional voltage drop between the igniter 52 and the coil 40.
- Fuse 66 provides an extra layer of protection in the event that the shunt resistor 56 fails. The higher the current rating of fuse 66, the longer the circuit 50 will take to turn off in the event of a catastrophic failure . However, too low a rating may cause the fuse to undesirably blow during normal circuit 50 operation.
- the hold open circuit of FIG. 4 can be described as several equivalent circuits comprising various series and parallel combinations of components.
- Fuse, 66, resistor 54 and direct current coil 40 form a first series combination that forms a first parallel combination with shunt resistor 56.
- the first parallel combination forms a second series combination with hot surface igniter 52.
- Capacitors 58 and 60 may have exemplary values ranging from about 15pF to about 30pF, preferably from about 18pF to about 25pF, and more preferably from about 20pF to about 24pF.
- Direct current coil 40 has a threshold (rms) current ranging from about 30mA to about 90mA, preferably from about 40 mA to about 80 mA, and more preferably from about 50 mA to about 70 mA.
- Resistors 54 and 56 may have exemplary resistance values ranging from about 20W to about 40W, preferably from about 25W to about 35W, and more preferably from about 28W to about 32W.
- Fuse 66 may be rated, for example, for about 0.5A to about 1.5A, preferably from about 0.6A to about 1.3 A, and more preferably from about 0.8A to about 1.2A.
- Hot surface igniter 52 comprises a silicon ceramic body with a rare earth sintering aid and a molybdenum disilicide sintering aid protective agent.
- the rare earth oxide sintering aid is present in an amount ranging from about 12 to about 14 percent of the ceramic body by weight.
- the molybdenum disilicide sintering aid protective agent is present in an amount ranging from about 5.5 percent to about 6.5 percent by weight of the ceramic body.
- the balance (79.5 percent to about 82.5 percent by weight of the ceramic body) is silicon nitride.
- the conductive ink in the igniter 52 comprises tungsten carbide in an amount ranging from about 70 to about 75 percent by weight of the ink.
- Silicon nitride is provided in an amount ranging from about 18 to about 25 percent by weight of the ink.
- the same sintering aids or co-dopants described for the ceramic body are also included in an amount ranging about 2 to about 4 percent by weight of the ink.
- the thickness of the conductive ink circuit of the hot surface igniter (taken along the thickness axis) is not more than about 0.002 inches, preferably not more than about 0.0015 inches, and more preferably, not less than about 0.0004 inches and not more than about 0.0009 inches.
- Capacitors 58 and 60 have respective capacitance values of 22pF.
- Resistors 54 and 56 have resistance values of 30W.
- Direct current coil 40 has an inductance value of 0.0074mH.
- FIG. 10A depicts the input voltage at igniter 52 in volts versus time.
- Circuit 50 is operated in a full power mode in which switch 62 is closed.
- the capacitors 58 and 60 each have a capacitance of 22 pF and together act like a single capacitor with a capacitance of 44pF.
- the voltage signal seen by the igniter has an rms value of 130V, higher than that of the AC source signal owing to the smoothing effect of the capacitors on the ripple produced by diode 64 .
- FIG. 10B shows the current through igniter 52 and has a similar pattern with an rms value of 267 mA. At these voltage and current values, the igniter high temperature resistance would be about 471 W, and the estimated igniter surface temperature would reach about 2430°F at steady-state.
- FIGS. IOC and 10D show the voltage output from the igniter 52 and the current received by direct current coil 40, respectively. As would be expected, the waveforms have a shape similar to those of FIGS. 10A and 10B. However, the rms output voltage from the igniter 52 is 4.4V. The rms current to the direct current coil 40 is 201mA, which is sufficient to latch direct current coil 40 and cooking gas safety valve assembly 20 in the open position of FIG. 2.
- FIGS. 1 lC-1 ID show the reduced power mode case for the igniter 52 output voltage and the direct current coil 40 current.
- the average igniter 52 output rms voltage value is 4.1V.
- the average direct current coil 40 rms current is 185 mA. At these estimated current and voltage values, the igniter 52 would reach a surface temperature of about 2150°F at steady-state.
- FIG. 5 a portion of another exemplary cooking gas safety apparatus is depicted.
- the cooking gas safety apparatus comprises a hold open circuit 70 and cooking gas safety valve assembly 20, which includes direct current coil 40 (shown in the figure).
- hold open circuit 70 is powered by a source of alternating current 71 and converts it to a time-varying direct current so that known gas taps with direct current coils like coil 40 may be used.
- Hot surface igniter 52 is in selective electrical communication with direct current coil 40 depending on the state of Zener diode 72 (described below).
- Hold open circuit 50 of FIG. 4 uses two parallel capacitors, one of which is selectively connectable to the circuit 50 to provide full and reduced power modes for the igniter 52.
- hold open circuit 70 of FIG. 5 uses two parallel resistors 82 and 84, one of which (84) is selectively connectable to the hold open circuit (via switch 86) to provide full and reduced power modes. Resistors 82 and 84 are in parallel with one another when switch 86 is closed. When switch 86 is open, resistor 84 is not in electrical communication with the source of alternating current 71 and is effectively out of the hold open circuit 70.
- the parallel combination of resistors 82 and 84 is equivalent to a single resistor with a resistance that equals the product of their resistances divided by the sum of their resistances. The combined resistance will always be lower than each of the individual resistances.
- closing switch 86 places circuit 70 in full power mode
- opening switch 86 places circuit 70 in reduced power mode.
- Full power mode is preferably used during an ignition operation.
- Reduced power mode is preferably used during a cooking operation and provides a means of reigniting the cooking gas in the event of a flame out.
- the power provided to igniter 52 in the reduced power mode is from about 70 percent to about 90 percent, preferably from about 75 percent to about 85 percent, and more preferably from about 78 percent to about 82 percent of the power provided to igniter 52 in a full power mode.
- releasing the gas valve stem 26 after the direct current coil 40 has latched in the open position of FIG. 2 will cause switch 86 to open (to place circuit 70 in a reduced power cooking mode). Otherwise, switch 86 will remain closed.
- Direct current coil 40 is in series with a Zener diode 72 and fuse 78 to form a first series combination. The first series combination forms a first parallel combination with resistor 80.
- the second parallel combination of resistors 82 and 84 is in series with the first parallel combination to form a second series combination.
- the second series combination forms a third series combination with hot surface igniter 52.
- the third series combination and capacitor 74 form a third parallel combination that is in series with diode 76 and fuse 88.
- the second series combination consists of the first parallel combination and resistor 82 alone (i.e., without resistor 84).
- resistor 82 determines how hot igniter 52 will get in reduced power mode and impacts the igniter 52 temperature in full power mode.
- resistor 84 allows more current to flow through the circuit 70, causing the igniter 52 to get hotter in full power mode. Increased values of the resistance of resistor 84 will tend to decrease the power dissipated by igniter 52 in full power mode, whereas decreased resistance values of resistor 84 will tend to increase the power dissipated by igniter 52 in full power mode.
- Capacitor 74 is not selectively connected to the hold open circuit 70 but rather remains in electrical communication with the hot surface igniter 52 and direct current coil 40 at all times.
- capacitor 74 When diode 76 is forward-biased, capacitor 74 will charge until it reaches its saturation voltage. Once the capacitor is at its saturation voltage, if the AC source 71 voltage drops below the saturation voltage, capacitor 74 will begin discharging until the AC voltage exceeds the capacitor 74 voltage, at which point capacitor 74 will begin charging again.
- increasing values of the capacitance of capacitor 74 will flatten the ripple in the igniter 52 input voltage at node N52 in both the full and reduced power modes of operation and will also lower the AC supply voltage at which the valve assembly 20 releases to the closed position of FIG.
- the direct current coil 40 will still see the threshold current necessary to hold the valve disk 36 in the open position of FIG. 2.
- the power dissipated by the igniter 52 will increase in both the full and reduced power modes at higher capacitance values relative to lower ones.
- Resistor 80 acts as a current set resistor. As the current through igniter 52 increases, the voltage at resistor 80 increases. When the voltage at resistor 80 reaches the breakdown voltage of Zener diode 72, direct current coil 40 will receive current. Fuse 78 provides an extra layer of protection for direct current coil 40 in the event that resistor 80 fails. At excessively higher current ratings, direct current coil 40 may fail to close when circuit 70 fails. If the fuse 78 current rating is too low, the direct current coil 40 may shut valve 21 during normal operation. Fuse 88 provides overall circuit protection.
- hold open circuit 70 includes a Zener diode 72 in series with direct current coil 40.
- the Zener diode 72 is operated in reverse-biased mode. When the voltage input to the Zener diode drops below the Zener breakdown voltage, it stops allowing current to flow to the direct current coil 40, causing it to release valve magnetic disk 30 so that it is biased to the closed position of FIG. 1.
- the Zener diode 72 acts as a low voltage switch that ensures the direct current coil 40 does not hold open the valve disk 36 when the igniter 52 is not hot enough to ignite cooking gas.
- Hold open circuit 70 beneficially includes several features that prevent valve assembly 20 from remaining open in the case of circuit component failures. For example, if diode 76 fails by shorting, alternating current will flow through the direct current coil 40, causing it to release. Because the valve assembly 20 is a hold open valve assembly, gas will cease to flow to the burner(s) unless and until manual actuation of the gas knob stem 26 is performed. If diode 76 fails open, the direct current coil 40 will cease to generate a magnetic field, and valve assembly 20 will fail to the closed position of FIG.
- capacitor 74 fails by shorting, all the current will flow through capacitor 74 causing fuse 88 to blow and the valve assembly 20 to fail to the closed position of FIG. 1. If capacitor 74 fails open, at 60Hz on the AC signal, the current to the direct current coil will drop to zero, causing the valve assembly 20 to fail to the closed position of FIG. 1. [0101] If igniter 52 fails by shorting, too much current will flow though the circuit 70 and fuse 78 will blow, causing the valve assembly 20 to fail to the closed position of FIG. 1. If igniter 52 fails open, no current will reach the direct current coil 40, again causing the valve assembly 20 to shut off the flow of gas to the burner(s) by failing to the closed position of FIG. 1.
- resistor 82 fails open with switch 86 open, nothing will happen because there will be no closed path for current flow through direct current coil 40. If resistor 82 fails by shorting with switch 86 open or closed, igniter 52 will see a large spike in current, causing it to heat up significantly, which could lead to an igniter 52 failure. If resistor 82 fails open with switch 86 closed, igniter 52 will be operable in reduced power mode only. If resistor 84 fails open with switch 86 open or closed, igniter 52 will operate in reduced power mode only. If resistor 84 fails closed with switch 86 closed, the igniter 52 will see a large spike in current, causing it to heat up significantly, which may lead to an igniter 52 failure.
- the resistance values of resistors 82 and 84 may be decreased, which will increase the current flowing through igniter 52.
- the capacitance value for capacitor 74 may be increased. Increasing the capacitance of capacitor 74 provides more stored electrical energy when capacitor 74 discharges (i.e., when the output voltage from diode 76 falls below the saturation voltage of capacitor 74). As a result, the rms voltage seen by the igniter 52 increases, thereby increasing its surface temperature.
- capacitor 74 may have exemplary capacitance values ranging from about 60pF to about 80pF, preferably from about 65 pF to about 75 pF, and more preferably from about 66pF to about 70pF.
- Direct current coil 40 has a threshold (rms) current ranging from about 30mA to about 90mA, preferably from about 40 mA to about 80 mA, and more preferably from about 50 mA to about 70 mA.
- Direct current coil 40 also has an inductance ranging from about 0.005mH to about O.OlOmH, preferably from about 0.006mH to about 0.009mH, and more preferably from about 0.007mH to about 0.008mH.
- resistor 80 may have exemplary resistance values ranging from about 65 W to about 95 W, preferably from about 70 W to about 90 W, and more preferably from about 75 W to about 85 W. Increased resistance values for resistor 80 will tend to decrease the release voltage (i.e., the resistor 80 input voltage required for the direct current coil 40 to generate a magnetic field sufficient to hold the valve assembly 20 in the open position of FIG. 2) of the direct current coil 40 by allowing more current to flow through the coil 40 a given input voltage to resistor 80.
- Fuse 88 may be rated, as an example, for about 0.5A to about 1.5A, preferably from about 0.6A to about 1.3 A, and more preferably from about 0.8A to about 1.2A.
- Fuse 78 may be rated, as an example, from about 100mA to about 300mA, preferably from about 150mA to about 250mA, and more preferably from about 180mA to about 220mA.
- FIGS. 12C and 12D show the voltage output from the igniter 52 (i.e., the input voltage at resistor 80) and the current received by direct current coil 40, respectively.
- the waveforms have a shape similar to those of FIGS. 12A and 12B.
- the igniter 52 output rms voltage is 14.1 V
- the rms current to the direct current coil is 100 mA, which is sufficient to latch direct current coil 40 and cooking gas safety valve assembly 20 in the open position of FIG. 2.
- FIGS. 13A-13D are simulation results in reduced power mode, i.e., with switch 86 open.
- a reduced power mode is preferably used following ignition and during a cooking operation as a way of preventing flame outs while reducing energy costs and extending the life of igniter 52 relative to operating igniter 52 in a constant full power mode.
- FIG. 13 A shows the igniter 52 input voltage. The wave form is similar to that of FIG. 12A. However, the igniter 52 input rms voltage is 143.2 V. Referring to FIG. 13B, the igniter 52 rms current is 253 mA. At these estimated current and voltage values, the igniter 52 would have a high temperature resistance of about 446 W and would reach a surface temperature of about 2260°F at steady state.
- FIGS. 13C-13D show the reduced power mode case for the igniter 52 output voltage and the direct current coil 40 current.
- the average rms current of the direct current coil 40 is about 85 mA, and the igniter 52 output rms voltage value is 30.5V.
- Hold open circuits 50 and 70 are particularly suited for situations where the igniter 52 may be energized and remain part of the hold open circuit but receive insufficient current to reach the autoignition temperature of the cooking gas. However, it has been found that with certain igniters 52 that scenario is less likely. In such cases, if the igniter 52 fails to reach the autoignition temperature, the circuit 50 or 70 will have failed as an open circuit.
- FIG. 14 a portion of another exemplary cooking gas safety apparatus is depicted which comprises a single mode valve driver hold-open circuit 130.
- Circuit 130 is powered by a source of alternating current 131.
- Hold-open circuit 130 converts the alternating-current to a time- varying direct current so that known gas taps with direct current coils like coil 40 may be used.
- an additional switch would be provided to selectively connect the source of alternating current 131 to the remainder of hold-open circuit 130 when a user actuates the valve assembly 20 by depressing and turning the gas knob stem 26.
- Hot surface igniter 52 is in electrical communication with direct current coil 40.
- the term “single mode” refers to the fact that hold-open circuit 130 has a full power mode but no reduced power mode. Thus, igniter 52 can reignite the cooking gas following a flame out by remaining at full power.
- Capacitor 136 smooths the ripple in the DC signal provided by diode 132 When diode 132 is forward-biased, capacitor 136 will charge until it reaches is saturation voltage, at which point charging stops. When the diode 132 voltage drops below the saturation voltage of capacitor 136, capacitor 136 will begin to discharge until the AC voltage exceeds the capacitor 136 voltage, at which point it will start charging again.
- Capacitor 136 has a capacitance value of from about 20pF to about 40pF, preferably from about 25pF to about 35pF, and more preferably from about 28pF to about 32pF. As the capacitance of capacitor 136 increases, the igniter 52 input voltage at node N52 will tend to flatten (show “less ripple”).
- the direct current coil 40 has an inductance ranging from about 6mH to about 9mH, preferably from about 6.5mH to about 8.5mH, and more preferably from about 7.0mH to about 8.0mH.
- a hold-open circuit 130 as shown in FIG. 15 is provided.
- Hot surface igniter 52 is as described in Example 1.
- Capacitor 136 has a capacitance of 30 pF.
- Direct current coil 40 has an inductance of 7.5 mH.
- the circuit is simulated with a 120VAC (rms) 60 Hz voltage source signal.
- FIG. 16A depicts the input voltage at igniter 52 in volts versus time at node N52.
- the input voltage signal seen by the igniter 52 has an rms value of 118V.
- FIG. 16B shows the current through igniter 52 and has an rms value of 259mA.
- the igniter 52 would have a high temperature resistance of about 457 W, and the igniter 52 surface temperature would reach about 2340°F at steady-state
- FIGS. 16C and 16D show the voltage output from the igniter 52 and the current received by direct current coil 40, respectively. As would be expected, the waveforms have a shape similar to those of FIGS. 16C and 16D.
- the rms current to the direct current coil 40 is 259 mA, which is sufficient to latch direct current coil 40 and cooking gas safety valve assembly 20 in the open position of FIG. 2.
- FIG. 15 an exemplary portion of a cooking gas safety apparatus is depicted which comprises a dual mode valve driver hold-open circuit 140.
- the hold-open circuit 140 may be operated in full and reduced power modes.
- the power provided to igniter 52 in the reduced power mode is from about 70 percent to about 90 percent, preferably from about 75 percent to about 85 percent, and more preferably from about 78 percent to about 82 percent of the power provided to igniter 52 in a full power mode.
- Alternating current source 141 supplies alternating current to diode 140 which converts the alternating current to a time-varying direct current.
- Capacitors 146 and 148 are provided and are in parallel with one another when switch 150 is closed to electrically connect capacitor 148 to the remainder of hold-open circuit 140.
- Capacitor 146 smooths or flattens the ripple in the input voltage and current to igniter 52 (i.e., at node N52) when hold open circuit 140 is in either the full or reduced power modes.
- Capacitor 148 smooths or flattens the ripple in the input voltage and current to igniter 52 (i.e., at node N52) when hold open circuit 140 is in the full power mode.
- capacitors 146 and 148 When switch 150 is closed, the two parallel capacitors 146 and 148 act as a single capacitor having a capacitance equal to the sum of their respective capacitance values. When switch 150 is open, capacitor 148 is not in the circuit and the total capacitance of the parallel combination of capacitors 146 and 148 equals the capacitance of capacitor 146. In certain exemplary implementations, capacitors 146 and 148 have capacitance values that range from about 10pF to about 20pF, preferably from about 12 pF to about 18pF, and more preferably from about 14pF to about 16pF. Direct current coil 40 has the inductance values described previously. When in full power mode, as the capacitance of either or both capacitors 146 and 148 increases, the igniter 52 input voltage and current tend to have less ripple (become flatter), whereas at lower values the converse is true.
- Hot surface igniter 52 is in series with direct current coil 40.
- switch 150 When switch 150 is open, capacitor 146 forms a parallel combination with the series combination of igniter 52 and direct current coil 40.
- switch 150 When switch 150 is closed, the parallel combination of capacitors 146 and 148 forms a parallel combination with the series combination of igniter 52 and direct current coil 40.
- igniter 52 has a high temperature resistance of about 457 W, and the estimated igniter surface temperature would reach about 2330°F at steady-state [0125]
- FIGS. 16C and 16D show the voltage output from the igniter 52 and the current received by direct current coil 40, respectively when hold-open circuit 140 is operated in full power mode. As would be expected, the waveforms have a shape similar to those of FIGS. 16C and 16D.
- the rms current to the direct current coil 40 is 259 mA, which is sufficient to latch direct current coil 40 and cooking gas safety valve assembly 20 in the open position of FIG. 2.
- a hot surface igniter as described in Example 1 is provided and which has a room temperature resistance of 87W.
- the igniter is placed in hold-open circuit 140 having the component values previously described and subjected to a 120 VAC rms source voltage.
- the time in seconds required to reach 1800°F and 2138°F is provided in Table 4:
- thermocouple introduces a significant amount of lag time because of the dynamics of the thermocouple’s response to the ignited flame.
- Circuits 50, 70, 130, and 140 instead rely on the electrical condition of the igniter 52 to indicate that ignition has occurred or will occur quickly enough to allow gas valve 21 to remain open after the user releases the gas knob. This is possible, at least in part, because of the superior time to ignition temperature properties of the hot surface igniters disclosed herein as suitable for use as igniter 52 relative to known hot surface igniters.
- hot surface igniter 52 is not operatively connected to a thermocouple of a flame sensor.
- hot surface igniter 52 as opposed to a spark igniter, to ignite cooktop burner gas is that the igniter can stay continuously energized (at full or reduced power) to provide ignition in the event of a flame-out. This property of hot surface igniters also makes a number of other features possible.
- a template circuit 90 which comprises a hot surface igniter 52.
- FIG. 6 does not show a hold-open circuit or a gas valve with a hold- open coil.
- a gas valve would be provided, and the circuit 90 would be configured such that when the gas valve is actuated, hot surface igniter 52 would be energized via switch 94 to coordinate the flow of gas to the burner with the supply of electricity to the igniter 52.
- Diode 92 is selectively connectable to the circuit 90 via switch 94. When switch 94 is in contact with switch pole 96, diode 92 is connected to circuit 90 and half-wave rectifies the current supplied to igniter 52.
- a number of sensors or indicators may also be used in positions 102 and 104 to document information about the electrical status of igniter 52.
- the sensors or indicators may be used alone or in combination with one another.
- a timer may be provided which accumulates the total time the igniter 52 is energized. The energization time data may then be used to determine how much of the expected igniter 52 life remains so that the igniter 52 may be replaced before failing.
- Such collected information may also be transmitted wirelessly by wi-fi, Bluetooth, and other known wireless communication technologies to a user’s smart phone, a personal computer, a laptop, or a server to provide information about the status of the igniter 52 remotely.
- Audible indicators may also be used in positions 102 and 104.
- a pot sensor may also be provided.
- a pot sensor determines when a pot is present on the burner (e.g., by sensing a weight change).
- the pot sensor may include or be operatively connected to a pressure switch or a plunger that completes circuit 90 only when a pot is present on the burner, which may help prevent fires.
- hold-open circuit 110 is similar to that of FIG. 4.
- Direct current coil 40 is part of a gas safety valve assembly 20 of FIGS. 1 and 2.
- Various sensors and indicators may be used at positions 114 and 116.
- Hold-open circuit 110 comprises a diode 130 that functions similarly to diode 64 of FIG. 4.
- Parallel capacitors 120 and 124 smooth the ripple voltage of diode 130 when switch 126 contacts pole 128 (full power mode).
- Capacitor 120 smooths the ripple voltage in reduced power mode (with switch 126 open).
- Resistor 122 is in series with direct current coil 40 and limits the current received by direct current coil 40.
- Shunt resistor 118 shunts the excess current needed to run igniter 52 relative to what is required to hold open the cooking gas safety valve assembly 20 (FIG. 2).
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Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
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EP21831645.3A EP4176206A1 (en) | 2020-07-01 | 2021-06-30 | Cooktop gas safety valve hold open circuit with ceramic heater |
CA3177140A CA3177140A1 (en) | 2020-07-01 | 2021-06-30 | Cooktop gas safety valve hold open circuit with ceramic heater |
JP2022576870A JP2023531886A (en) | 2020-07-01 | 2021-06-30 | Gas safety valve open holding circuit for stove using ceramic heater |
CN202180039417.7A CN115667802A (en) | 2020-07-01 | 2021-06-30 | Gas safety valve opening keeping circuit of cooking range surface with ceramic heater |
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US202063047088P | 2020-07-01 | 2020-07-01 | |
US63/047,088 | 2020-07-01 |
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PCT/US2021/039785 WO2022006213A1 (en) | 2020-07-01 | 2021-06-30 | Cooktop gas safety valve hold open circuit with ceramic heater |
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US (1) | US20220003419A1 (en) |
EP (1) | EP4176206A1 (en) |
JP (1) | JP2023531886A (en) |
CN (1) | CN115667802A (en) |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4865539A (en) * | 1988-08-23 | 1989-09-12 | Robertshaw Controls Company | Fuel control unit for a gas furnace and method of making the same |
US6474492B2 (en) * | 2001-02-22 | 2002-11-05 | Saint-Gobain Ceramics And Plastics, Inc. | Multiple hot zone igniters |
US20050269420A1 (en) * | 2004-06-08 | 2005-12-08 | Donnelly Donald E | Apparatus and methods for operating a gas valve |
US20190301741A1 (en) * | 2018-03-27 | 2019-10-03 | SCP Holdings, LLC | Hot surface igniters for cooktops |
-
2021
- 2021-06-30 US US17/363,232 patent/US20220003419A1/en active Pending
- 2021-06-30 CA CA3177140A patent/CA3177140A1/en active Pending
- 2021-06-30 CN CN202180039417.7A patent/CN115667802A/en active Pending
- 2021-06-30 EP EP21831645.3A patent/EP4176206A1/en active Pending
- 2021-06-30 JP JP2022576870A patent/JP2023531886A/en active Pending
- 2021-06-30 WO PCT/US2021/039785 patent/WO2022006213A1/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4865539A (en) * | 1988-08-23 | 1989-09-12 | Robertshaw Controls Company | Fuel control unit for a gas furnace and method of making the same |
US6474492B2 (en) * | 2001-02-22 | 2002-11-05 | Saint-Gobain Ceramics And Plastics, Inc. | Multiple hot zone igniters |
US20050269420A1 (en) * | 2004-06-08 | 2005-12-08 | Donnelly Donald E | Apparatus and methods for operating a gas valve |
US20190301741A1 (en) * | 2018-03-27 | 2019-10-03 | SCP Holdings, LLC | Hot surface igniters for cooktops |
Also Published As
Publication number | Publication date |
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CA3177140A1 (en) | 2022-01-06 |
CN115667802A (en) | 2023-01-31 |
US20220003419A1 (en) | 2022-01-06 |
EP4176206A1 (en) | 2023-05-10 |
JP2023531886A (en) | 2023-07-26 |
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