ES2311185T3 - GAS BURNER WITH A SUPPLY CIRCUIT OF A SAFETY VALVE FOR THE IGNITION OF SUCH GAS BURNER. - Google Patents

Abstract

Safety valve power supply circuit for the ignition of a gas burner, said safety valve (2) being powered by a flame detecting thermocouple (3). The power supply circuit (1) comprises conditioning means (4) for converting an input signal (E) into an output signal (S) able to maintain the safety valve (2) open, and said input signal (E) is generated by the energy accumulated in a capacitor (5), said capacitor (5) being charged when the gas burner is activated.

Description

Gas burner with a power circuit of a safety valve for igniting said burner of gas.

Technical sector

The present invention relates to a burner of gas comprising a safety valve and a circuit of power fed by a thermocouple.

Prior state of the art

Safety valves are known powered by thermocouples for use in gas burners. He thermocouple keeps the safety valve open as far as That exists flame. In case the flame disappears the valve security closes, thus cutting off the gas supply. The group safety formed by the safety valve and the thermocouple gives place to an intrinsically safe device, since any type of failure in said security group causes the closure of the safety valve and therefore the cut of the supply of gas.

A problem with these safety valves is that, when the gas burner is lit, time goes by determined until the thermocouple is able to hold the valve Open security alone. A first solution to this inconvenient is to make the user, acting on the gas burner knob to turn it on, hold that knob press and hold the safety valve open long enough for the thermocouple to acquire the minimum temperature needed to be able to maintain the safety valve open while there is a flame.

A second solution is to add a auxiliary power circuit that provides the valve with security the energy needed to keep it open when the gas burner is activated.

EP1113227A2 describes a device for the ignition of a gas burner comprising a valve security. Said device comprises a power circuit together with the safety valve that keeps said safety valve after activation of the gas burner. Saying power circuit is connected to the mains voltage through a switch controlled by a timer. In this way, the power circuit is connected to the mains voltage during the time necessary for the thermocouple to operate the valve Security alone.

In the described device, a failure in the switch or on any of the timer components can make the power circuit permanently connected to the mains voltage, with the consequent problem of lack of security because of the risk that this entails for the Username.

EP1113227A2 solves this problem of lack of safety by adding a fuse that blows in case the time the power circuit is connected to the mains voltage exceeds a predetermined maximum time. This solution has the disadvantage that it is difficult to establish which has if said predetermined maximum time. Another problem is that When the fuse blows, it must be replaced.

DE2123458A1 discloses a power circuit of a safety valve. Said circuit comprises a thermocouple. which is not connected directly to the safety valve, and a capacitor that acts as a timer or as a switch temporary acting on a relay.

US4505253A describes a water heater with a control circuit comprising a capacitor and a circuit of discharge for said capacitor including a switch that connects the capacitor to the power source in a rest position and when the switch is activated connect the capacitor to a solenoid that activates a safety valve associated with the thermocouple A grip element is used to maintain a stem in an intermediate position in which the switch is activated after a command is released.

DE3724084A1 discloses a gas burner according to the preamble of claim 1.

Exhibition of the invention

The object of the invention is to provide a gas burner with a valve feed circuit of safety for the ignition of a gas burner that provides safety against failures of the circuit itself.

The power circuit, which applies to safety valves powered by a thermocouple detector flame, comprises means for conditioning an input signal to turn it into an output signal suitable for keeping open the safety valve, such that said input signal is generated from the energy accumulated in a capacitor, said capacitor charging at the moment when the gas burner.

Therefore, the energy supplied to the safety valve after activation of the burner will be the energy  accumulated in a capacitor, and not the energy supplied from of the mains voltage. Thus, it is achieved that failures in the circuit of supply do not assume that the safety valve is maintained open indefinitely, since once the energy is used up accumulated in the condenser the power circuit could not Continue to keep the safety valve open.

Moreover, the power circuit of The invention is a simple and low cost circuit.

These and other features and advantages of the invention will become apparent in view of the figures and of the Detailed description of the invention.

Description of the drawings

Fig. 1 is a schematic view of a First embodiment of the invention.

Fig. 2 is a schematic view of a second embodiment of the invention.

Fig. 3 is a schematic view of the embodiment of Fig. 2 for a plurality of valves security.

Fig. 4 is a block circuit of the conditioning means of the circuit of the invention.

Fig. 5 is a first embodiment of the conditioning means of the circuit of the invention.

Fig. 6 is a second embodiment of the conditioning means of the circuit of the invention.

Fig. 7 is a third embodiment of the conditioning means of the circuit of the invention.

Detailed statement of the invention

With reference to figure 1, the circuit of supply 1, which acts a safety valve 2 and which is powered by a thermocouple 3 flame detector, comprises means of conditioning 4 to convert an input signal E into a S output signal suitable for keeping the safety valve open 2. Said input signal E is generated from the energy accumulated in a condenser 5.

Said capacitor 5 is charged at the moment in the The gas burner is activated. In this first embodiment, the circuit 1 comprises a switch 6 that connects the capacitor 5 to the mains voltage Vr at the moment in which the user activates the burner, disconnecting it immediately after. More concretely, the user, to activate the burner, press a knob 7, the capacitor 5 is connected to the voltage via switch 6 of network Vr at the moment in which the control 7 is kept pressed. Circuit 1 also comprises a spark generator 8 which is also activated by switch 6.

In a second embodiment of the invention, shown in figure 2, circuit 1 comprises a switch 6 ' which connects the capacitor 5 alternately to the mains voltage Vr and to the conditioning means 4. Switch 6 'connects the capacitor 5 at the mains voltage Vr at the instant in which the user activates the burner, and immediately after, connects it to the conditioning means 4.

As in the first embodiment, the user, to activate the burner, press a knob 7, connecting by means of the switch 6 'the capacitor 5 to the mains voltage Vr in the moment in which the control 7 is held down.

With reference now to figure 3, when the circuit 1 feeds a plurality of safety valves 2, 2a, 2b, ... and 2n, said circuit 1 comprises a switch 6 ', 6'a, 6'b, ... and 6'n for each safety valve 2, 2a, 2b, ... and 2n. Said switches 6 ', 6'a, 6'b, ... and 6'n are connected, according to is shown in figure 3, such that the capacitor 5 is charge when any of the burners is activated, and said condenser 5 connects to the conditioning means 4 only if none of the switches 6 ', 6'a, 6'b, ... and 6'n connect the capacitor 5 with the mains voltage Vr.

With reference to figure 4, the means of conditioning comprise a regulator block 10 that receives the input signal E, an oscillator block 11, a transformer 12 and a rectifier 13 that generates the output signal S.

The conditioning means 4 comprise also a rectifier and limiter block 9 that is used for the capacitor charge 5. As shown in the embodiments of Figures 5, 6 and 7, the rectifier and limiter block 9 comprises a zener diode D1 with a transistor Q1 connected in emitter follower, such that said transistor Q1 conducts only until the capacitor 5 reaches a voltage determined Vc.

The three embodiments of the means of conditioning 4 shown in figures 5, 6 and 7 comprise a oscillator block 11 that receives a signal from capacitor 5, a transformer 12 that receives the output signal from said oscillator 11, and a rectifier 13 that receives the output signal from the transformer 12 and generates the output signal S that receives the corresponding safety valve 2.

The embodiments of Figures 5 and 6 they also comprise a regulator block 10 by which it is generated a decreasing voltage from the input signal E. The block oscillator 11 receives said decreasing voltage. In this way, the energy supplied by circuit 1 to the valve corresponding security 2 is greater at the beginning and decreases progressively

In the embodiment of Figure 5, the rectifier 13 comprises a diode D for each safety valve 2. In the embodiment of Figure 6, on the other hand, rectifier 13 it comprises, instead of diodes D, a bipolar transistor Q for each safety valve 2. In this embodiment the transformer 12 It comprises two windings: a first winding 12a that feeds the safety valve and a second winding 12b by means of which excites the base of each transistor Q.

Using bipolar transistors Q instead of diodes D, the voltage drop of 0.6 V in the diodes is reduced to 0.15 V in the transistors, thus reducing losses in the same proportion and therefore a capacitor 5 of a capacity between two and three times less.

In the embodiment of Figure 7, the rectifier 13 comprises a low MOSFET transistor Q ' resistance between source and drain for each safety valve 2. MOSFET Q 'transistors need a generation circuit of door signal 14. In this embodiment, transformer 12 it also comprises a second winding 12b, in this case for power the door signal generation circuit 14. With MOSFET transistors, the voltage drop in them is reduced up to 10 mV, thus reducing losses with respect to the two previous embodiments and thus allowing the use of a capacitor 5 of a smaller capacity.

In this last embodiment, it can be done work to transformer 12 in inductance mode. In this way, when the primary of said transformer 12 receives energy, the MOSFET transistors Q 'are in cut. When the Primary power supply, the MOSFET Q 'transistors enter conduction as a result of the reaction of transformer 12 to release its magnetic energy.

The operation in inductance mode allows, as seen in figure 7, dispense with the regulator block 10 and make the oscillator block 11 receive the signal from E input directly. In this way, the losses that occur in the regulator block 10 they are eliminated.

Claims (13)

1. Gas burner comprising a safety valve (2), a thermocouple (3) flame detector, and a supply circuit of the safety valve for the ignition of the gas burner, said safety valve (2) being directly fed by the thermocouple (3) flame detector, and the power circuit (1) comprising a capacitor (5) that is charged with a mains voltage (Vr), obtaining from the energy accumulated in said capacitor (5), due to said load, an electrical signal (E) that is used to temporarily supply said safety valve (3) to keep it open, said capacitor charging (5) being carried out by momentarily activating a switch (6, 6 ') to temporarily connect the capacitor (5) to the mains voltage (Vr), said switch activation (6, 6 ') occurring simultaneously with the activation of the gas burner, characterized in that the energy supplied to the safety valve (2) is the energy accumulated in the capacitor (5), adapted by means of the conditioning means (4), said conditioning means (4) converting the electrical signal (E) obtained from the energy accumulated in the condenser (5) into an electrical signal outlet (S) that is applied directly to said safety valve (2) to feed it, and to keep it open. 2. Gas burner according to claim 1, in where said capacitor (5) is always connected to the means of conditioning (4). 3. Gas burner according to claim 1, in wherein said switch (6 ') is a switch (6') arranged for connect the capacitor (5) alternately to the mains voltage (Vr) or to the conditioning means (4), the capacitor (5) to the mains voltage (Vr), to charge it, when the switch (6 ') is momentarily activated, and when the condenser (5) to the conditioning means (4) when the switch (6 ') is not activated, or in a rest position, to allow its discharge when the capacitor (5) is charged. 4. Gas burner according to any of the previous claims, comprising a command (7) for activating  the gas burner, said command (7) acting on said switch (6.6 ') to activate it momentarily when said command (7) is held momentarily. 5. Gas burner according to claim 4, comprising a spark generator (8) that is connected to the mains voltage (Vr) when said switch (6, 6 ') is activated, to generate a spark that produces burner ignition. 6. Gas burner according to claims 3 or 4 when it depends on claim 3, wherein said circuit feeds a plurality of safety valves (2, 2a, 2b, ..., 2n) and comprises a switch (6 ', 6'a, 6'b, ..., 6'n) for each valve safety (2, 2a, 2b, ..., 2n), said switches being (6 ', 6'a, 6'b, ..., 6'n) connected in such a way that the capacitor (5) is charged when any of the burners is activated, and said condenser (5) is connected to the conditioning means (4) only if none of the switches (6 ', 6'a, 6'b, ..., 6'n) connect the capacitor (5) to the mains voltage (Vr). 7. Gas burner according to any of the previous claims, comprising a rectifier block and limiter (9) for capacitor charging (5). 8. Gas burner according to claim 7, in where the rectifier and limiter block (9) comprises a diode zener (D1) with a transistor (Q1) connected in emitter follower, such that said transistor (Q1) conducts only until the capacitor (5) reaches a certain voltage (Vc). 9. Gas burner according to any of the previous claims, wherein the means of conditioning (4) comprise an oscillating block (11) that receives a signal from the capacitor (5), a transformer (12) receiving the output signal of said oscillator (11), and a rectifier (13) that receives the output signal from the transformer (12) and generates the output signal (S) received by the valve corresponding security (2). 10. Gas burner according to claim 9, wherein the conditioning means (4) also comprise a regulator block (10) by which a voltage is generated decreasing from the input signal (E), receiving the oscillating block (11) said decreasing voltage. 11. Gas burner according to claim 10, wherein the rectifier (13) comprises a diode (D) for each safety valve (2). 12. Gas burner according to claim 10, wherein the rectifier (13) comprises a bipolar transistor (Q) for each safety valve (2), comprising the transformer (12) a second winding (12b) whereby the base of the each transistor (Q). 13. Gas burner according to claims 9 or 10, wherein the rectifier (13) comprises a MOSFET transistor (Q ') of low resistance between source and drain, for each valve safety (2) and a door signal generation circuit (14), the transformer (12) comprising a second winding (12b) by means of which said signal generation circuit is fed Door (14).