JPH0424290Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a safety device for forced air premix burners and other all-primary air burners.

(Prior Art) Conventionally, this type of device has a high-temperature fuse installed in the head of the gas burner, and when the primary air becomes excessive and flashback occurs, the fuse blows out and an on-off valve is installed in the gas supply path. It is known that a thermocouple for detecting high temperature is used in place of the fuse, and the heat-sensitive part of the thermocouple faces the combustion surface of the burner, and the cold junction faces the mixing part. It is also known that when a back flame is generated, the cold junction is heated and the on-off valve is closed so that a predetermined electromotive force cannot be obtained from the thermocouple. A combustion case containing a built-in pneumatic burner is housed, and a mixture of gas ejected from a nozzle at the end of a gas supply path and air discharged from a fan in an arbitrary ratio is supplied to the burner. The burner undergoes complete primary combustion, and a thermocouple for detecting low temperature is placed at the suction port of the fan, and when combustion exhaust leaks from the combustion casing into the combustor main body, the hot air is detected by the thermocouple and the switch is opened/closed. There are also known devices in which the valve is closed.

(Problems to be Solved by the Invention) However, in the conventional device described above, when detecting both the occurrence of flashback and combustion exhaust leakage from the combustion casing, temperature detection means must be provided individually. When detecting the combustion exhaust leak at the suction port of the fan, the intake air and the combustion exhaust are not sufficiently mixed, so the combustion exhaust must be able to touch the heat sensitive part of the thermocouple installed at the suction port. Moreover, since the flow velocity of the combustion exhaust gas is low at the suction port, there is a problem in that heat cannot be transferred well to the heat-sensitive section.

(Means for Solving the Problems) In order to solve the above problems, the present invention includes a combustion case in which a primary air burner is built in the combustor main body,
A fan for supplying a mixture of fuel gas and primary air to the burner is housed, and an intake port is provided in which a space formed between the combustion casing and the combustor main body serves as an intake passage to the fan. Prohibits the supply of fuel gas to the fan when the internal temperature of the burner detected by a temperature detection means provided in the combustor body and located near the air-fuel mixture supply port inside the burner is equal to or higher than a predetermined value. It is characterized by having a shutoff valve.

(Function) The present invention has the above-mentioned configuration. According to this, when a gas with a fast burning rate, such as 6C gas, is used, if for some reason the amount of primary air supplied exceeds the amount of gas supplied, A flashback phenomenon occurs and a flashback occurs in the head of the burner, but the temperature rise in the mixing section due to this flashback is immediately detected by the temperature detection means, and the supply of fuel gas is prohibited based on the detected temperature. ,
The flashback does not continue, therefore, the flashback does not reach the fan, and the fan's blades and motor are not damaged.

Furthermore, if the combustion casing is damaged and the internal combustion exhaust leaks, the combustion exhaust will leak between the combustion casing and the combustor main body, that is, into the intake passage of the fan, so it will leak out of the combustor main body. It is inhaled into the fan along with the air without being released into the air. After being uniformly mixed with air in the fan, the mixture is supplied to the burner, and the temperature detection means disposed near the mixture supply port of the burner where the flow velocity of the mixture is high is detected by the combustion exhaust gas. When a temperature rise due to contamination is detected, the supply of combustion gas is stopped in the same way as above, ensuring safety.

(Example) Next, an example in which the present invention is applied to a gas water heater will be described based on the drawings.

In the drawings, reference numeral 1 denotes a gas water heater main body having an intake port 2 at the top and an exhaust pipe 3 at the top, and inside the main body 1, a heat exchanger 4 and a burner 5 for heating the heat exchanger 4 are provided in the middle of the main body 1. , a fan 6 for supplying primary air, which is combustion air, to the burner 5 in the lower part thereof,
A combustion case 8 having an exhaust port 7 connected to the exhaust pipe 3 is housed in the upper part of the interior, and the water sent from the water supply pipe 9 on the upstream side of the heat exchanger 4 is heated in the heat exchanger 4. Hot water at a set temperature is obtained from a hot water outlet pipe 10 on the downstream side of a heat exchanger 4, and combustion exhaust gas in a combustion case 8 is discharged to the outside via an exhaust pipe 3. In the figure, reference numeral 11 indicates a gas supply path in which a nozzle 11a at the tip faces the suction port of the fan 6 for supplying gas to the burner 5, and an electromagnetic proportional control valve 12 is interposed in the gas supply path 11. .

The amount of gas supplied to the burner 5 and the amount of air supplied to the burner 5 are controlled to increase or decrease by a general combustion control device 13 equipped with an operational amplifier. Solenoid proportional control valve 1 according to the magnitude of the difference signal between
This is done by changing the opening degree of the fan 2 and the rotation speed of the fan 6.

Here, in the present invention, a temperature sensor 15 for detecting the temperature inside the burner 5 is provided in the vicinity of the air-fuel mixture supply port in the burner 5, that is, in the mixing part 5b, and an on-off valve 16 interposed in the gas supply path 11 is provided. The temperature sensor 1
The valve is closed when the temperature sensor 5 detects a predetermined low temperature.
5 is composed of a thermistor that detects a predetermined temperature set to a relatively low temperature, and the on-off valve 16 is composed of an electromagnetic on-off valve interposed on the upstream side of the electromagnetic proportional control valve 12 in the gas supply path 11. , inputting a temperature detection signal from the thermistor to the combustion control device 13,
When this temperature detection signal reaches the above-mentioned predetermined temperature, for example, 80 degrees Celsius or higher, in other words, the temperature exceeds a temperature that may damage the fan 6 due to the flashback phenomenon, or when combustion exhaust gas leaks from the combustion casing 8. At this time, the combustion control device 13 immediately stops energizing the coil of the electromagnetic on-off valve, closes the electromagnetic on-off valve, and stops the supply of gas to the burner 5.

In the illustrated embodiment, a thermistor is used as the temperature detector 15, but the present invention is not limited to this, and any device capable of detecting the relatively low predetermined temperature may be used, such as a low-temperature fuse or a thermocouple for low-temperature detection.

(Effects of the Invention) As described above, according to the present invention, the occurrence of the flashback phenomenon and the leakage of combustion exhaust due to damage to the combustion casing can be detected with one temperature detection means. In addition, it is possible to detect combustion exhaust gas leaking from the combustion casing without releasing it outside the combustor body, and it is more reliable than the conventional method of detecting the leakage at the fan suction port. Can be detected.

[Brief explanation of the drawing]

The drawings are explanatory diagrams showing one example of implementation of the present invention. 1... Gas water heater main body (combustor main body), 5...
All primary air burner, 5b...mixing section, 6...fan, 11...gas supply path, 11a...nozzle,
15...Temperature detector, 16...Opening/closing valve.

Claims (1)

[Scope of utility model registration request] In a combustor body that houses a combustion case housing an all-primary air burner and a fan that supplies a mixture of fuel gas and primary air to the burner, the combustion case and the combustor main body are connected to each other. An intake port is provided in the combustor main body, with a space formed therebetween serving as an intake passage to the fan, and a temperature inside the burner is detected by a temperature detection means disposed near the mixture supply port inside the burner. A safety device for an all-primary air burner using forced air supply, comprising a shutoff valve that prohibits the supply of fuel gas to the fan when the temperature is above a predetermined value.