MXPA99004352A - Electric lighter for - Google Patents

Abstract

The present invention relates to an electric lighter for gas (40) wherein a discharge generating circuit (45) has input terminals (41, 42) that are connected to a supply source (43), and at least one exit terminal (3) to generate the sparks. The gas lighter has a filter (70) to eliminate electromagnetic noise and in turn a single capacitor (71) having a first terminal that communicates with a reference potential (73), and a second terminal that communicates with a (42) of the input terminals (41, 42) by means of the resistor. (fig

Description

ELECTRIC LIGHTER FOR GAS The present invention relates to an electric lighter for gas, which can be applied, for example, to a gas stove that is used in the kitchen. The gas stoves that are known, are adapted with built-in electric gas lighters, which work manually to produce sparks and ignite the gas flames in the stove. One type of gas stove with an electric gas lighter (Figure 1), comprises gas metal burners 2, each provided with a respective electrode 3. Located on the side of the burner 2 and electrically isolated with respect to the metal surface to ground 4 that supports the burners. When in operation, the electric gas lighter produces a spark between each electrode 3 and the respective burner 2, to ignite the flame of the burner supplied with gas. Figure 1 shows a complete circuit diagram of a known type of electric gas lighter. In addition to the electrodes 3, the gas lighter comprises a first and second terminal 7, 8 which is connected to a supply line, for example to an alternating main line (not shown), closing a switch (not shown); and an electric shock generating circuit 5 interposed between the input terminals 7, 8 and the electrodes 3, and to produce sparks at the electrodes 3. The circuit 5 comprises a resistor 9 having a first terminal connected to the output terminal 7, and a second terminal connected to the anode of a rectification diode 10, whose cathode is connected to a first node 11. The circuit 5 also comprises a capacitor 12 having a first terminal connected to the node 11, and a second terminal connected to a node 13, which in turn is connected to a second input terminal 8. The circuit 5 also comprises a device of voltage discharge 15 having a first terminal connected to the node 11, and a second terminal connected to a first terminal 16a of a primary coil 16 of a transformer 17. The coil of the transformer 17 has a second input terminal 16b connected to the node 13 , and a transformer 17 also comprising two identical secondary coils 18, each of which has much more turns than the primary coil 16. The terminals of each secondary coil 18 are connected to the respective electrodes 3. The gas lighter operates from the Following way: When the switch (not shown) is closed to connect the gas lighter circuit to the alternating supply line, the voltage of the alternating main lines is rectified by means of the diode 10 and a rectified voltage is applied to charge the capacitor 12. When the voltage at the terminals of the capacitor reaches a threshold value VTH equal to the ignition threshold value of the arrester , the transformer 17 and the capacitor 12 are connected, and the capacitor 12 is discharged by means of the primary coil 16. A discharge current Isc of extremely high intensity (for example a peak 150-280 A) is then generated and flows through the primary coil 16, to the terminals, from which a discharge voltage VI is generated. (for example 400 V) during the transient discharge phenomenon (which lasts a few microseconds). The discharge voltage VI induces, at the terminals of the secondary coils 18, a voltage V2 much greater than VI (for example 28 kV) and which is applied to the electrodes 3. For each secondary coil 18, the voltage V2 is sufficient to produce sparks between each electrode 3 and the metal burner 2, which is grounded. Lighters for gas of the aforementioned type have the drawback of generating, at the outlet (ie toward the main supply lines) and during the transient discharge phenomenon, severe electromagnetic noise above the limits established by European standards ( EN55014 and subsequent).

A proposed solution to the problem is to adapt the gas lighter to an electronic filter to reduce the electromagnetic noise at the outlet and thus obtain a lighter for low noise gas, as shown in Figure 2. In addition to the components described above (indicated using the same reference numerals), a low noise gas lighter comprises an electronic filter 20 interposed between terminals 7, 8 and a circuit 5a equivalent to circuit 5 but having no resistor 9. Filter 20 comprises a first decoupling resistor 25a having a first terminal connected to the terminal 7 and a second terminal connected to the node 22 communicating with the anode of the diode 10 and with a first terminal of the capacitor 21a, having a second terminal connected to a reference potential (to ground). The filter 20 also comprises a second decoupling resistor 25b, having a first terminal connected to the node 23 communicating with the node 13 and with a first terminal of a capacitor 21b, having a second terminal connected to the reference potential (a Earth) . The capacitors 21a and 21b are then located between the respective nodes 22 and 23 and a common node 24 that functions as ground. The filter 20 defines a preferred path by which the electromagnetic energy that occurs during the transient discharge phenomenon of the capacitor 12 is discharged. More specifically, said energy is transmitted by the capacitors 21a and 21b directly to ground 24 to reduce electromagnetic emissions that are produced by the circuit to the main supply lines. Although the filter 20 is in fact provided to reduce the level of noise generated during the operation, well below the prescribed limit, the gas lighters adapted with filters 20 do not present any inconvenience.

Although minimum for each gas lighter, the expense of providing the filter with two capacitors is far from insignificant on a mass production scale, such as in the household appliance industry. It is an object of the present invention to provide an electric igniter for gas which is highly direct, and which at the same time is provided to eliminate the drawbacks associated with gas lighters of the type described above. According to the present invention, an electric gas lighter is provided, as mentioned in Claim 1. A non-limited embodiment of the present invention will be described by means of an example with reference to the accompanying drawings, in which: which: Figure 1 shows a schematic electrical diagram of a known electric igniter for gas without filter; Figure 2 shows a schematic electrical diagram of a known electric lighter for gas, adapted to a filter; Figure 3 shows a schematic electrical diagram of an electric gas lighter showing a filter according to the teachings of the present invention. Figure 3 shows a gas lighter 40 comprising a first and second input terminal 41, 42 which are connected to an alternate supply line 43 when closing a switch 44; and an electric shock generating circuit 45 interposed between the input terminals 41, 42 and the electrodes 3, and to produce sparks at the electrodes 3. The circuit 45 comprises a resistor 47 having a first terminal connected to the terminal 41, and a second terminal connected to the anode of a rectifying diode 48, which cathode is connected to a first node 50. The circuit 45 also comprises a capacitor 52 having a first terminal connected to the node 50, and a second terminal connected to the node 53. The circuit 45 also comprises a resistor 55 parallel to the capacitor 52; and a known discharger 57 (for example a hi-energy and solid-state Sidac gas tube) having a first terminal connected to node 50, and a second terminal connected to a first terminal 60a of a primary coil 60 of a transformer 61. The primary coil 60 of the transformer 61 has a second input terminal 60b connected to the node 53, and a transformer 61 also comprises two identical secondary coils 62, each of them has much more turns than the primary coil 60. The terminals of each secondary coil 62 are connected to respective electrodes 3, each one in front and at a short distance from a metal portion of a respective burner 2. A filter 70 comprises a single capacitor C capacitor 71, which has a first terminal connected to a reference potential (ground) 73, and a second terminal that communicates with the node 53 by means of an electrical line 54, the which also communicates directly with the terminal 60b of the primary coil 60. The second terminal of the capacitor 71 also communicates with the input terminal 42 by means of a resistor 65 of resistance R. Preferentially but not exclusively, the capacitance C of the capacitor 71 is in nanofarads (for example ranges between 1 and 4.7 nanofarads); the resistance R is in tens of kilohms (for example it is approximately 15 kilohms); and the filter 70 opes in the frequency range of 150 kHz to 300 MHz and has an average attenuation of approximately 20 dB.

In actual use, when switch 44 is closed, the voltage of the main lines is applied to the terminals 41 and 42, so that a rectified voltage is applied to charge the capacitor 52. When the voltage at the terminals of the capacitor 52 reaches a threshold value equal to the ignition threshold value of the arrester 57, the transformer 60 and the capacitor 52 are connected , and the capacitor 52 is discharged by means of the primary coil 60. Therefore, a discharge current of extremely high intensity is generated and flows through the primary coil 60, at the terminals, from which a voltage of discharge (for example 400 V) during the transient discharge phenomenon (which lasts a few microseconds). The discharge voltage induces, at the terminals of the secondary coils 62, a voltage much greater than the discharge voltage and which is applied to the electrodes 3. A spark 80 is then generated between each electrode 3 and the outer body of the burner respective 2, and is accompanied by instantaneous current flow between the two burners 2 of each pair of electrodes 3, and through the metal surface that supports and grounds the burners. The advantages of the filter 70 are as follows. By using a single capacitor, opposed to the two, not only is the lighter for gas simplified, but it is provided to reduce production time and cost, which in terms of mass production, provides considerable savings, even at Eliminate a single component The filter of two capacitors of the gas lighter, described with reference to Figure 2, was based on the preconceived idea that a filter of two capacitors was the only possible way to effectively reduce electromagnetic noise, which was considered impossible use a filter with a single capacitor. In real events, the gas-lighter tests, according to the invention, have shown the effectiveness of the filter 70 to be equal, if not greater, than the filter of the two capacitors in Figure 2, and that most of the of the electromagnetic noise flows along the line 54 adapted to the filter 70. As such, being adapted along the line 54, extending directly between the terminal 60b of the primary coil 60 and the input terminal 42, the filter 70 is provided to block most electromagnetic noise. Obviously, changes can be made to the electric lighter for gas described and illustrated herein, however without departing from the scope of the present invention.

Claims (6)

1. CLAIMS 1. • An electric gas lighter where a discharge generator circuit comprises the input terminals, which are connected to a supply source; and at least one output terminal to generate sparks; said gas lighter also comprises a filter for filtering the electromagnetic noise; Which is characterized in that said filter comprises a single capacitor having a first terminal communicating with a reference potential, and a second terminal communicating with one of the input terminals, by means of the first major resistance lines.
2. 2. . A gas lighter as recited in Claim 1, wherein said discharge generating circuit comprises: - Main capacitor lines connected to said input terminals by means of main rectification lines; Main discharge lines connected to said main lines of the capacitor to discharge the accumulated current in said main lines of the capacitor, in the primary coil of a transformer that has at least one secondary coil that communicates with the output terminal.
3. 3. A gas lighter, as mentioned in claim 2, characterized in that the filter is located along a line extending directly between a terminal of the primary coil and one of the input terminals.
4. 4 # A gas lighter, as mentioned in Claim 2 or 3, characterized in that it comprises secondary main lines of resistance, interposed between one of the terminals and the main rectification line.
5. 5. < A lighter for gas, as mentioned in one of claims 2 to 4, characterized by comprising main third resistance lines, parallel to said main lines of the capacitor.
6. 6. A gas lighter as mentioned in one of the preceding Claims, characterized in that said capacitor has a capacitance C in nanofarads, and the main resistance lines have a resistance (R) in tens of kilohms. 7. "A gas lighter, as mentioned in any of the preceding Claims, characterized in that the filter operates in the frequency range of 150 kHz to 30 a MHz. • A gas lighter, as mentioned in any of the preceding Claims, characterized in that the filter has an average attenuation of approximately 20 dB. . An electric igniter for gas, described and illustrated substantially with reference to the accompanying drawings.