JPS6133396Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a burner that is used for heating hot water, etc. and is capable of switching between gas combustion and oil combustion with a single burner, and relates to a safety device for the burner. It is.

In this type of dual-purpose burner, if one fuel is being burned while switching to the other, a large amount of fuel will be supplied to the high-temperature combustion chamber, causing explosive ignition, which is extremely dangerous. . The present invention prevents explosion and ignition by stopping combustion when the fuel is mistakenly switched during combustion, and will be specifically explained below based on an embodiment shown in the drawings.

Reference numeral 1 denotes a burner circuit connected in series with a power supply via an operating switch 2 and a normally closed contact 3 of a safety relay described below, and a transformer 23 connected to the burner circuit via a normally open contact 22 of a blower motor 19 and a relay 29 described later.
The gas solenoid valve 4 and the oil pump 5 are connected to each other, and a switch 6 for supplying different types of fuel is provided which can arbitrarily switch the energization to the gas solenoid valve 4 and the oil pump 5. 7 is a wind pressure switch, and 8 is a pre-purge circuit, which reduces the output voltage of the comparator 10 by charging the capacitor 9 after a set time. Reference numeral 11 denotes a thermo circuit, which changes the output voltage of the comparator 14 to high or low by changing the voltage divided by the variable resistor 12 and thermistor 13, and controls the transistors 15 and 16 to be in a cutoff state or a conduction state. Reference numeral 17 denotes a pre-check circuit that is energized by the conduction of the transistor 16, and this circuit checks for conduction breakdown of the transistor 19, which is controlled by the burner control circuit 18 at the next stage.
The contact point 3 is opened by operating the burner control circuit 18. Under normal conditions, for example, the contact point 21 is closed after a certain period of time to energize the burner control circuit 18. Incidentally, when the burner control circuit 18 detects ignition, it keeps the transistor 19 in a conductive state and switches on the relay 29.
This allows the ON operation to continue. A transistor 24 shortens the thermistor 13 during prepurge to prevent the transistor 16 from conducting. Reference numeral 25 denotes a prohibition circuit according to the present invention, which has a parallel circuit of capacitors 27 and 28 that are selectively energized by a changeover switch 26 that is interlocked with the supply changeover means 6, and the fixed contact side of the changeover switch 26 is connected to a pre-purge circuit. 8 power supply line, and a parallel circuit is connected to the base of transistor 24. 30 is a check circuit for the transistor 19; 31 and 32 are discharge paths of capacitors 27 and 28, respectively. 33 is a capacitor connected to the base of the transistor 19.

The present invention has the above configuration, and the operation switch 2
When the power is turned on, the blower motor 19 is energized to blow air, and when the air pressure switch detects air blowing, the capacitor 9 of the pre-purge circuit 8 is charged, and after a certain period of time, the output voltage of the comparator 10 decreases and the transistor 24 is cut off, and therefore transistors 15 and 16 of the thermocircuit 11 are both conductive, energizing the pre-check circuit 17. At this time, the check circuit 29 is conductive, that is, when the transistor 19 is conductive, the safety relay 20 is activated. , if the transistor 19 is in the cutoff state, the contact 21 is closed, the burner control circuit 18 is energized, the relay 29 is activated, the contact 22 is closed, and the gas solenoid valve 4 and the transistor 23 are connected, for example. The gas is combusted by energizing it.

In other words, the combustion sequence in the present invention is that first a pre-purge is performed, then a pre-check is performed, then combustion starts, and the thermo circuit 11 is turned off.
After operation, a pre-check is performed and then combustion is performed.

Now, to explain what happens if you accidentally switch to oil combustion during gas combustion, selector switch 26
is switched in conjunction with the supply switching means, so when the switch 26 switches to the capacitor 27, initially the capacitor 27 has no charge, so the transistor 24
The base potential of capacitor 27 rises and becomes conductive, thus shorting the thermistor 13 and cutting off transistors 15 and 16. However, as time passes, the charging voltage of capacitor 27 rises and transistor 24 becomes conductive.
The base potential of transistors 15 and 16 also decreases.
becomes conductive again. Then, due to the conduction of the transistor 16, the pre-check circuit 17 is made conductive, and the transistor 19 is checked again. By the way, the above-mentioned charging of the capacitor 27 is carried out in an extremely short period of time, and therefore the cut-off of the transistor 16 is instantaneous.Therefore, when the transistor 19 is checked again by the pre-check circuit, the transistor 19 absorbs the charge of the capacitor 33. Since it is not completely discharged, it is in a conductive state, and the check circuit 30 becomes conductive, the safety relay 20 is activated, and the contact 3
It opens and stops combustion.

Note that the above-mentioned safe operation is limited to the time of combustion (in this embodiment, after the pre-purge is completed), and since the ON-OFF interval of the thermo circuit is long during normal thermo operation, the capacitor 33 is sufficiently discharged when checking again. Since transistor 19 is in a cut-off state, no safe operation is performed.

As described above, according to the present invention, it is possible to completely prevent explosions and ignitions caused by fuel switching during combustion in a burner that uses different types of fuels, and it is possible to provide an extremely safe burner of this type. .

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram showing an embodiment of the present invention. 6... Supply switching means, 25... Prohibition circuit.

Claims (1)

[Scope of utility model registration request] A device that can be used for different types of fuels, characterized by having a means for switching the supply of different types of fuels, and having an inhibition circuit that cuts off electricity to the burner control circuit and stops combustion in conjunction with the switching operation of the switching unit during combustion. Safety device in burner.