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
• • 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
  • F23N5/102—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2227/00—Ignition or checking
  • F23N2227/02—Starting or ignition cycles
• • 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
  • F23N2227/30—Ignition circuits for pilot burners
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2227/00—Ignition or checking
  • F23N2227/36—Spark ignition, e.g. by means of a high voltage

Definitions

• the invention relates to a method for igniting a gas stream and a circuit arrangement for carrying out this method, as can be used in particular in gas control fittings for a gas heating furnace.
• the ignition device for igniting gases is described in US Pat. No. 5,722,823 A.
• the ignition device has a magnet coil which actuates a gas valve, an igniter for the electrical ignition of the gas flow and a remote control which is connected to the magnet coil and the ignition via a low-voltage line.
• the remote control includes a power supply and a timer for the timed provision of low voltage.
• a voltage for holding the magnet insert is provided via a power supply unit.
• the ignition takes place via a piezoelectric spark ignition.
• the power supply is switched off when the thermal current provided by a thermocouple is sufficient to hold the ignition safety valve in the open position.
• DE 93 07 895 U describes a multi-function valve with a thermoelectric fuse for gas burners of heating systems.
• Multi-function valve uses the existing mains power supply of a room to operate it.
• a solenoid valve is excited via a push button, which opens the ignition safety valve.
• the gas flow is ignited.
• a thermocouple located in the area of the ignited gas flame is heated and brings a magnet insert into the excited state via the resulting thermal current.
• the magnet holds an armature and thus also the ignition safety valve connected to the armature in the open position. Now the push button can be released and the solenoid valve can be de-energized.
• the invention is based on the problem of developing a method for fully automatic ignition of a gas stream and a circuit arrangement for carrying out this method which have such a low power consumption that an integrable voltage source can be used while ensuring a sufficient service life. Furthermore, the structure should be as simple and inexpensive as possible.
• the armature On account of the ignition safety magnet activated by the holding current, the armature is held in this position after it has been installed and via an ignition transformer via an ignition capacitor connected ignition electrode in a known manner generates an ignition spark for igniting the outflowing gas. Subsequently, further ignition processes are initiated in that the ignition capacitor is recharged and a new ignition spark is generated after charging. Ignition is ended after a predetermined time. The holding current flowing from the voltage source to the ignition fuse magnet is interrupted and the circuit existing between the ignition fuse magnet and the thermocouple is closed again via the relay.
• thermocouple there is an advantageous embodiment of the method if the presence of a thermal voltage is measured, further ignition processes, as described above, being initiated in the absence of thermal voltage. Ignition is stopped if there is detectable thermal voltage. As soon as electronically from the measured thermal voltage If the calculated thermal current is sufficient to hold the armature on the ignition fuse magnet, the holding current flowing from the voltage source to the ignition fuse magnet is interrupted and the circuit existing between the ignition fuse magnet and the thermocouple is closed again via the relay.
• a higher alternating voltage is generated from the direct voltage provided by the voltage source by using a power oscillator instead of the converter and the storage capacitor only when the ignition process is initiated to a first stage of a multiple cascade connected downstream of the power oscillator is switched, whereupon the storage capacitor and the ignition capacitor electrically conductively connected to the second stage of the multiple cascade are charged to predetermined higher DC voltages by means of the higher AC voltage via the cascade circuit.
• the power oscillator is switched off and switched on again when further ignition processes are initiated.
• the voltage source consists of a battery, the dimensions of which can be made so small that they are located together with the electronic control unit in the housing of a receiver part Remote control
• the holding current provided by the voltage source for holding the armature can flow simultaneously via the ignition safety magnet and the relay, with an additional current being generated briefly at the time the circuit between the ignition safety magnet and thermocouple is closed in order to reliably prevent that the armature when switching the relay due to the brief power interruption position of the switching contacts of the relay drops.
• the voltage of the holding current made available to the ignition safety magnet by the voltage source is converted into the millivolt range via an additional transverter.
• a method step which, after a defined period of time, additionally interrupts the excitation of the ignition safety magnet via the voltage source by one or more independent, time-controlled safety shutdowns connected in series.
• Fig. 1 is a schematic representation of the circuit arrangement
• Fig. 2 is a detailed representation of the power oscillator
• Fig. 3 shows a detailed representation of the analog amplifier.
• the exemplary circuit arrangement according to the invention shown in FIG. 1 for carrying out the method for igniting a gas stream is used in a gas control valve.
• This gas control valve is a switching and control device, which is preferably intended for installation in a gas-heated stove or the like. It enables the operation and monitoring of a burner by controlling the amount of gas flowing to the burner.
• the gas control valve has a pilot burner 1 and an ignition safety valve 2. The structure and function of the pilot burner 1 and the ignition safety valve 2 are familiar to the person skilled in the art and are therefore not explained in more detail here.
• a microcomputer module serves as the electronic control unit and, in this exemplary embodiment, is located together with a voltage source 10 in a separate, location-independent housing (not shown) of the receiver part of a remote control.
• a voltage source 10 in this case size R6, serve as voltage source 10.
• the first stage of the cascade 12 serves to control and supply the downstream storage capacitor C1.
• an electromagnet 5 which, as shown schematically in the illustration, serves to actuate a known ignition protection valve 2. Due to the short-term load, a thermally undersized so-called pulse magnet 5 is sufficient.
• the second stage of the cascade 13 is used to control and supply the secondary ignition capacitor C2, which is part of an ignition device which is known per se and is therefore not explained in more detail here.
• the ignition capacitor C2 can be controlled by the microcomputer module for ignition via a port C.
• the second stage of the cascade 13 is connected to an element 14 for voltage monitoring.
• the element 14 serves to limit the maximum voltage that occurs in order to prevent components from being destroyed. Additional voltage monitoring for the storage capacitor C1 can be dispensed with here, since after the ignition capacitor C2 has been charged, the storage capacitor C1 can also be charged.
• Port D is used to report back to the microcomputer module.
• the circuit of the power oscillator 11 used is shown in detail in FIG. 2.
• the power oscillator 11 consists of a CMOS circuit 15 with at least four gates, which is known per se to the person skilled in the art. These gates can be NOR gates, NAND gates, simple negators or the like. Subordinate to them is a complementary field effect power stage 16, which is followed by an LC series resonant circuit consisting of coil L1 and RF capacitor C3. An RC element serves as a so-called phase shifter 19 for feedback and phase adjustment.
• an ignition safety magnet 6 belonging to the ignition safety valve 2 is connected to a thermocouple 4.
• the circuit breaker of a monostable relay 17 is additionally arranged in this circuit, whereas in the excited state this circuit is open and the ignition safety magnet 6 is energized by the voltage source 10 formed by the batteries.
• a switching element in this case a transistor T1, which can be controlled by the microcomputer module via port G, is connected on the one hand to the voltage source 10 and on the other hand to the relay 17.
• a resistor R1 is additionally arranged in parallel with relay 17, since the holding current required for ignition safety magnet 6 is higher than the current flowing through relay 17.
• a transistor T2 and a transistor T3 are connected to this circuit. While the transistor T2, which is preceded by a resistor R3, is connected to the negative pole of the voltage source 10 and can be controlled by the microcomputer module via the port F, the transistor T3 is connected to the positive pole of the voltage source 10 and can be connected via the port E by the microcomputer module can be controlled.
• an analog amplifier 20 is connected in parallel to the thermocouple 4 in the circuit arrangement.
• This analog amplifier 20 has the task of measuring, amplifying and converting a direct voltage of the thermocouple 4 that occurs in the millivolt range and converting it into a variable that can be processed by the microcomputer module. Since the DC amplifiers which are otherwise customary for such cases on the one hand require an additional auxiliary voltage above the operating voltage and on the other have drift deviations, for example due to temperature influences, the analog amplifier 20 is designed as an AC voltage amplifier.
• a field effect transistor T4 which can be controlled by the microcomputer module via port L and a resistor R2 form a controllable voltage divider.
• the voltage divider is followed by a pre-amplifier V1 and a post-amplifier V2, each of which is assigned a coupling capacitor C4 / C5.
• the reference potential is formed by the plus voltage in order to eliminate fluctuations in the on-board voltage.
• the reference potential is formed by ground in the post-amplifier V2.
• Both amplifiers V1 / V2 and a trigger TR are put into operation by the microcomputer module via port K since they are deactivated as a power saving measure when not in use.
• the trigger TR located behind the post-amplifier V2 is in turn connected to the microcomputer module via port I.
• the command to ignite is given to the microcomputer module via the remote control.
• the analog amplifier 20 activated via port K checks whether a thermal voltage is present at the thermocouple 4 and the corresponding information is sent via port I to the microcomputer module. While there is a thermal voltage, which is synonymous with a burning pilot flame, the ignition process is interrupted, when there is no thermal voltage, the voltage divider of the analog amplifier 20 is controlled by the microcomputer module via port L. By switching the voltage divider once, the DC voltage present at the thermocouple 4 at this point in time is converted into an AC voltage pulse. The pulse reaches the preamplifier V1 via the coupling capacitor C4.
• the signal coming from the pre-amplifier V1 is coupled via the coupling capacitor C5 to the post-amplifier V2 and amplified again.
• This analog signal coming from the post-amplifier V2 is digitized by the trigger TR at defined trigger points, as can be seen in the diagram associated with FIG. 3.
• the curve of the voltage U over time t is plotted in the diagram.
• the trigger TR is used at a predetermined voltage level SE Initiation of the pulse signal IS at the time TL a first trigger point TR1 and when the voltage of the pulse signal IS drops a second trigger point TR2, to which a time TE is assigned.
• the time interval between the two times TL and TE is a measurement signal MS.
• the measurement signal MS obtained in this way from the existing thermal voltage reaches the microcomputer module via port I for evaluation.
• the length of the measurement signal MS is directly proportional to the thermal voltage present at the thermocouple 4.
• the ignition process While there is a thermal voltage, i.e. of an already burning pilot flame, the ignition process is terminated, the thermal oscillator 11 is activated in the absence of a thermal voltage by the microcomputer module via port J and the storage capacitor C1 is connected via port A to the first stage 12 of the multiple cascade.
• the resonant circuit begins to oscillate via the feedback element, i.e. the resonant circuit becomes the self-oscillating and frequency-determining power oscillator 11.
• This alternating voltage is used to charge the storage capacitor C1 and the ignition capacitor C2 with the aid of the two cascade stages 12/13 of the multiple cascade until the element 14 used for voltage monitoring and limitation of the maximum voltage occurring responds and sends a signal to the microcomputer module via port D, which then switches off the power oscillator 11 via the port J.
• the time-controlled safety shutdowns 18 are activated via the port M and the ignition safety magnet 6 is supplied with a holding current coming from the voltage source 10 via the transistor T1 controlled by port G by energizing the relay 17 and thus the circuit between the ignition safety magnet 6 and the thermocouple 4 is opened.
• the storage capacitor C1 is suddenly discharged.
• the storage capacitor C1 is then separated from the cascade stage 12 via port A.
• the pulse magnet 5 is briefly excited by this current surge and a plunger 7 is moved against the force of a closing spring 8 until the armature 3 comes to rest on the ignition safety magnet 6. Due to the flowing holding current, the armature 3 is held in this position and thus the ignition safety valve 2 in the open position.
• the gas can flow through the gas control valve to pilot burner 1.
• the excitation of the ignition safety magnet 6 via the voltage source 10 is additionally interrupted by one or more independent and time-controlled safety shutdowns 18 and the ignition safety valve 2 does not remain in the Open position, but is closed again by the closing spring 8.
• the ignition device is activated via port C by the microcomputer module, the ignition capacitor C2 discharges and the ignition spark 9 jumps at the ignition electrode 9, as a result of which the escaping gas is ignited.
• the analog amplifier 20 is activated via the ports K and L and a check is carried out to determine whether there is already a detectable voltage on the thermocouple 4 due to the beginning of heating by the burning pilot flame, i.e. at least approx. 1 mV is present.
• thermocouple 4 If the minimum voltage is present, of course no further ignition processes are initiated, but the existing open circuit voltage of the thermocouple 4 is checked further until the size of the current electronically calculated therefrom is sufficient as a holding current for the ignition safety magnet 6.
• the analog amplifier 20 is then deactivated via port K and the current flowing from the voltage source 10 to the ignition protection magnet 6 is interrupted via port G.
• the relay 17 is de-energized and the switching contacts of the relay 17 close the circuit between the thermocouple 4 and the ignition safety magnet 6.
• the armature 3 is now held by the thermal current.
• the transistor T2 is briefly activated via the port F at the time of switching and an additional one is also briefly activated via the resistor R3 Generates electricity that the above Falling of the anchor is prevented with certainty.
• the command to switch off is given to the microcomputer module via the remote control.
• port G and port E By briefly activating port G and port E, a current surge is sent through the relay 17, bypassing the safety shutdowns 18 and the ignition safety magnet 6, the switching contacts of which thus briefly lift off.
• the holding current flowing between thermocouple 4 and ignition safety magnet 6 is thus interrupted.
• the armature 3 is no longer held by the ignition safety magnet 6 and the ignition safety valve 2 closes under the action of the closing spring 8.
• the gas supply to the pilot burner 1 and, of course, to the main burner (not shown) is interrupted and the gas flame extinguishes.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Control Of Combustion (AREA)
• Electrically Driven Valve-Operating Means (AREA)
• Magnetically Actuated Valves (AREA)

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• 2003
  • 2003-02-13 DE DE10305928A patent/DE10305928B3/de not_active Expired - Fee Related
• 2004
  • 2004-02-12 DK DK04710374.2T patent/DK1592923T3/da active
  • 2004-02-12 WO PCT/EP2004/001300 patent/WO2004072555A1/de active Application Filing
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• 2006
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