JPS6133408Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a gas combustion device with an electromagnetic safety valve, and more specifically, it is operated by an electromotive force generated in a thermocouple disposed within the flame of a pilot burner. The present invention relates to a gas combustion device with an electromagnetic safety valve, which is operated by an electromotive force not generated in an oxygen concentration difference sensor disposed within the flame after ignition, and is provided with an electromagnetic safety valve that opens and holds gas supply passages to the two burners.

[Prior art]

In general, gas combustion equipment with an electromagnetic safety valve was developed to prevent incomplete combustion from continuing by stopping the gas supply to both burners when incomplete combustion occurs in the main burner. occur sometimes
The oxygen concentration difference caused by CO generates an electromotive force in the oxygen concentration difference sensor, and this electromotive force closes the electromagnetic safety valve to stop gas supply to both burners. For this reason, in conventional gas combustion devices of this type, if an abnormality occurs in the oxygen concentration difference sensor itself, the electromagnetic safety valve cannot be closed even if incomplete combustion occurs in the main burner, resulting in a malfunction. Complete combustion continues, and in this respect it cannot be said that safety (fail-safety) is sufficient.

In order to deal with such problems, the applicant filed a
-125439 (Utility Model Publication No. 60-42264) has been filed for the following gas combustion device with an electromagnetic safety valve. In other words, the device is activated by an electromotive force generated in a thermocouple placed within the flame of the pilot burner, and after the main burner is ignited, it is activated by an electromotive force generated in an oxygen concentration difference sensor placed within the flame. An electromagnetic safety valve is provided to keep gas supply passages to both burners open, and the oxygen concentration difference sensor is arranged at a location that generates an electromotive force during normal combustion in the flame of the main burner but does not generate an electromotive force during abnormal combustion. A normally closed switch that is connected in series to the thermocouple and opened in conjunction with the gas supply operation to the main burner is connected in series to the thermocouple, the oxygen concentration difference sensor, and the electromagnetic coil of the electromagnetic safety valve. It is characterized in that the connection circuit is connected in parallel to the oxygen concentration difference sensor.

[Problem that the invention attempts to solve]

By the way, the oxygen concentration difference sensor used in the gas combustion device described above is equipped with an oxygen concentration cell made of an oxygen ion conductive solid electrolyte such as zirconia and electrode layers such as porous platinum coated on both sides. This reduces the internal resistance from about 100MΩ to about 20Ω, and when a difference in oxygen concentration occurs between the two electrode layers after reaching a predetermined temperature, an electromotive force of 700mv to 800mv is generated. In addition, in this type of oxygen concentration difference sensor, as shown in Fig. 3, two
The electromotive force value E stabilizes in about 3 seconds, but the current value I does not stabilize until about 10 to 15 seconds. That is, it takes a considerable amount of time to activate this type of oxygen concentration difference sensor. Therefore, in the gas combustion device with an electromagnetic safety valve,
Incomplete combustion occurring in the main burner cannot be detected until the oxygen concentration difference sensor becomes active.

[Means for solving problems]

The present invention has been made in order to deal with such problems, and is based on the above-mentioned oxygen concentration difference sensor in the gas combustion apparatus with an electromagnetic safety valve, which is related to the applicant's earlier application, and which generates an electromotive force during normal combustion in the flame of the main burner. In addition, the sensor is disposed in a location where no electromotive force is generated during abnormal combustion, and a portion of the sensor is located in or near the flame of the pilot burner at a location that is preheated by the pilot burner.

[Functions and effects of the idea]

According to this configuration, the oxygen concentration difference sensor becomes active in a very short time after the main burner is ignited by the action of the pilot burner. Therefore, incomplete combustion of the main burner can be detected immediately after ignition, and this is compatible with the fact that the electromagnetic safety valve is activated by the thermocouple that detects the flame of the pilot burner before the sensor is activated. With regard to dust, the safety of this type of gas combustion apparatus with an electromagnetic safety valve can be further improved.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings. FIG. 1 shows an example of a gas combustion apparatus with an electromagnetic safety valve according to the present invention. This gas combustion device with an electromagnetic safety valve (hereinafter sometimes simply referred to as a gas combustion device) is built into a gas water heater, and the main gas passage 12 which is the gas supply passage to the main burner 11 has a pilot gas passage. 13 are branched. Further, an electromagnetic safety valve 20 is interposed in the main gas passage 12 at a position upstream from the pilot gas passage 13.
An automatic on-off valve 30 is interposed at a downstream side of the valve 3. The electromagnetic safety valve 20 includes an electromagnet 21 and a suction plate 2.
2 and a valve body 23, and a spring 26 that urges the operation rod 24 upward in the figure to seat the valve body 23 on the valve seat 25. When pushed, the upstream side of the main gas passage 12 is opened, and when a magnetic force is generated in the electromagnet 21 in this state, the operating rod 24 is attracted and held. Further, the automatic opening/closing valve 30 is connected to the water supply passage 14.
The actuating rod 31 is connected to the diaphragm of the hydraulic response device 15 installed in the valve, and the spring 33 urges the actuating rod 31 to the right in the figure to seat the valve body 31a on the valve seat 32. Exchanger 1
The downstream side of the main gas passage 12 is opened by supplying water to the main gas passage 6.

Accordingly, the electromagnet 21 of the electromagnetic safety valve 20 is equipped with an electromagnetic coil 21a having a large number of turns and a small resistance value per turn, which is a conventional electromagnet of this type. This electromagnetic coil 21a constitutes a part of the control circuit 40 of the electromagnetic safety valve 20, and as shown in FIG. The other end is connected to the (-) pole side of an oxygen concentration difference sensor 42 disposed within the flame of the main burner 11. The oxygen concentration difference sensor 42 is located at the boundary between the inner flame and the outer flame in the flame of the main burner 11 during normal combustion, and is also arranged at a position where a part of the lower surface of the sensor also contacts the flame of the pilot burner 17. It is set up. As a result, the oxygen concentration difference sensor 42 is preheated by the pilot burner 17, and during normal combustion of the main burner 11, the lower surface of the sensor is exposed to the inner flame and the upper surface of the sensor is exposed to the outer flame, which is caused by the difference in oxygen concentration between the inner and outer flames. Electricity is generated, and when the combustion is incomplete, the inner flame extends and the sensor,
Both sides are enveloped in internal flame, reducing or eliminating the electromotive force. The (+) pole side of the oxygen concentration difference sensor 42 is connected to the (-) pole side of the thermocouple 41, and the electromagnetic coil 21a, the thermocouple 41, and the oxygen concentration difference sensor 42 are connected in series with each other. In addition,
The thermocouple 41 is commonly used as a pilot observation sensor for this type of gas combustion apparatus, and has characteristics of an internal resistance of about 10 mΩ and an electromotive force of about 25 mV.

On the other hand, an actuation piece 31b is fixed to the actuation rod 31 of the automatic opening/closing valve 30.
A normally closed switch 43 is provided which is opened and closed by. This normally closed switch 43 is connected to the heat exchanger 1
The automatic opening/closing valve 30 is configured to be opened at the same time as the main gas passage 12 is opened by supplying water to the main gas passage 12. It is connected in parallel to the sensor 42. Further, a capacitor 44 is connected in parallel to the oxygen concentration difference sensor 42 and the normally closed switch 43 between the series-connected circuits.

In the gas combustion device configured in this way,
When not in use, the main gas passage 12 is closed by the electromagnetic safety valve 20 and the automatic on-off valve 30, and the normally closed switch 43 is closed. In this state,
When the gas main valve (not shown) is opened and the operating rod 24 of the electromagnetic safety valve 20 is pushed against the spring 26, the upstream side of the main gas passage 12 is opened and gas is supplied to the pilot burner 17 through the pilot gas passage 13. The igniter is activated and the pilot burner 17 is ignited.
As a result, the thermocouple 41 is heated to generate an electromotive force, and an exciting current is passed through the closed circuit of the thermocouple 41, the electromagnetic coil 21a, and the normally closed switch 43, and the electromagnet 21 is excited. As a result, the electromagnetic safety valve 2
The operating rod 24 of 0 is attracted and held by the electromagnet 21, and the main gas passage 12 is held open. During this time, the oxygen concentration difference sensor 42 is preheated by the pilot burner 17. Note that during this time, the oxygen concentration difference sensor 42 does not reach an active state and its internal resistance is large, so the thermocouple 41 and the electromagnetic coil 21a
And the closed circuit of the oxygen concentration difference sensor 42 is not energized. Next, when water is supplied to the heat exchanger 16, the automatic opening/closing valve 30 is activated to open the downstream side of the main gas passage 12, and gas is supplied to the main burner 11. Therefore, the main burner 11 is ignited by the pilot burner 17, and the oxygen concentration difference sensor 42, which has been preheated by the pilot burner 17, is heated during normal combustion and becomes active in a short time.
Note that the normally closed spring 43 is opened by the operation of the automatic opening/closing valve 30, but the oxygen concentration difference sensor 4
2 becomes active, a circuit is formed in which the capacitor 44 is charged from the thermocouple 41, an exciting current is applied to the electromagnetic coil 21a, and the electromagnetic safety valve 20 is connected to the upstream side of the main gas passage 12. Hold the side open. When the oxygen concentration difference sensor 42 becomes active, an excitation current is applied to the closed circuit of the oxygen concentration difference sensor 42, the thermocouple 41, and the electromagnetic coil 21a. As a result, due to the difference in internal resistance and generated electromotive force between the oxygen concentration difference sensor 42 and the thermocouple 41, the operating rod 24 of the electromagnetic safety valve 20 is attracted and held by the electromagnet 21 mainly by the electromotive force of the oxygen concentration difference sensor 42. , the main gas passage 12 is kept open. Further, when the water supply to the heat exchanger 16 is stopped in order to extinguish only the main burner 11, the automatic on-off valve 30 is closed and the normally closed switch 43 is closed. Therefore, an excitation current is applied to the closed circuit of the thermocouple 41, the electromagnetic coil 21a, and the normally closed switch 43 by the electromotive force generated in the thermocouple 41, and the upstream side of the main gas passage 12 is held open to open the pilot burner 17. Only ignition is maintained. Note that the delay in the closing operation of the normally closed switch 43 that occurs at this time, sudden and short-term fluctuations in the electromotive force of the oxygen concentration difference sensor 42 due to wind, etc. are compensated for by the discharge of the capacitor 44; In the gas combustion apparatus, when incomplete combustion occurs in the main burner 11, the electromotive force generated by the oxygen concentration difference sensor 42 disappears, and the closed circuit of the oxygen concentration difference sensor 42, thermocouple 41, and electromagnetic coil 21a is closed. It becomes energized. Therefore, the main gas passage 12 is closed by the electromagnetic safety valve 20, and subsequent incomplete combustion is blocked.

By the way, in the gas combustion apparatus, the oxygen concentration difference sensor 42 is disposed so that a part of the lower surface of the sensor contacts the flame of the pilot burner 17, so that the oxygen concentration difference sensor 42 is preheated by the pilot burner 17. After the main burner 11 is ignited, it becomes active in a very short time. Therefore, incomplete combustion of the main burner 11 can be detected quickly after the main burner 11 is ignited, and the oxygen concentration difference sensor 4
Coupled with the fact that the electromagnetic safety valve 40 is operated by the thermocouple 41 before the active state of 2,
The safety of this type of gas combustion device can be further improved.

Note that the present invention is not limited to the above-mentioned type of gas combustion device, but is operated by an electromotive force generated in a thermocouple placed within the flame of a pilot burner, and an oxygen concentration difference sensor placed within the flame after the main burner ignites. The present invention can be implemented in various types of gas combustion apparatuses equipped with electromagnetic safety valves, which are operated by an electromotive force generated in the electromagnetic force and keep open the gas supply passages to the two burners.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of a gas combustion device according to the present invention, Fig. 2 is a control circuit diagram of an electromagnetic safety valve in the gas combustion device, and Fig. 3 is a line showing the activation state of the oxygen concentration difference sensor over time. It is a diagram. Explanation of symbols, 11... Main burner, 12...
Main gas passage, 17...Pilot burner, 2
0...Solenoid safety valve, 21...Electromagnet, 21a...
Electromagnetic coil, 40... Control circuit, 41... Thermocouple, 42... Oxygen concentration difference sensor, 43... Normally closed switch.

Claims (1)

[Scope of utility model registration request] It is actuated by the electromotive force generated in a thermocouple placed within the flame of the pilot burner, and after the main burner ignites, it is actuated by the electromotive force generated in the oxygen concentration difference sensor placed within the flame, supplying gas to both burners. The oxygen concentration difference sensor is provided with an electromagnetic safety valve that keeps the passage open, and the oxygen concentration difference sensor is disposed in a part that generates an electromotive force during normal combustion in the flame of the main burner but does not generate an electromotive force during abnormal combustion. A portion of the sensor is located in or near the flame of the pilot burner at a location that is preheated by the burner, and the sensor is connected in series to the thermocouple, and is linked to the gas supply operation to the main burner. A gas combustion device with an electromagnetic safety valve, wherein a normally closed switch that is opened when the oxygen concentration sensor is opened is connected in parallel to the oxygen concentration sensor in a series connection circuit of the thermocouple, the oxygen concentration difference sensor, and the electromagnetic coil of the electromagnetic safety valve.