JPS6215623Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a gas fan heater that prevents the sound of extinguishing due to backfire during extinguishing without reducing the amount of air intake, and allows stable and clean primary air to be taken in. This invention relates to a gas fan heater capable of sustaining a combustion action.

Conventionally, Bunsen burners have been used for atmospheric pressure combustion in instantaneous water heaters, bathtubs, and the like. However, as products such as fan heaters that blow hot air from the outlet through the combustion chamber were developed and came into general use, some gases with relatively fast combustion speeds could cause backfire when extinguishing a fire. This has caused inconveniences such as the sound of extinguishing the fire. This is because when the combustion chamber is under positive pressure due to the convection fan, the flame is forced into the burner flame hole under negative pressure when extinguishing. Therefore, it has been proposed to reduce the amount of air taken into the burner from the nozzle to lower the combustion speed and make flashback more difficult. It has inherent disadvantages that may cause stability phenomena, etc., and also requires an operation and mechanism to reduce the amount of air intake, making it inconvenient in terms of structure and handling.

On the other hand, since the primary air intake port for supplying air to the Bunsen burner in the combustion chamber is provided outside the heat shielding partition plate, air that does not pass through the air filter is used as primary air. Therefore, when used for a long period of time, the primary air intake may become clogged with dust, and the primary air volume may be affected due to differences in the performance of the blower. The destabilization of the amount of air is also one of the factors that greatly promotes incomplete combustion and flame instability during fire extinguishing as described above.

Therefore, this idea was devised in consideration of the above circumstances, and by connecting the combustion chamber and the vicinity of the nozzle of the Bunsen burner through a pressure equalization chamber without reducing the amount of air intake, it is possible to An object of the present invention is to provide a gas fan heater that eliminates the generation of extinguishing noise due to backfire.

An embodiment of this invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is the main casing of the gas fan heater. A blower 4 consisting of a convection fan 3 rotated by a motor 2 is arranged at the bottom of the casing 1, and a combustion chamber 5 is defined in the center of the casing 1. will be accomplished. A ventilation passage 6 is provided on the back side of the combustion chamber 5. Further, an air outlet 7 equipped with a louver is formed at the upper front surface of the casing 1 . Combustion chamber 5
A Bunsen burner 9 is disposed below. This Bunsen burner 9 has a nozzle section 8 and a flame hole section 11, and fuel is supplied from the nozzle section. Here, the gas fuel includes fuel obtained by gasifying petroleum.

In the Bunsen burner 9, the nozzle part 8
The fuel gas from the burner and the surrounding primary air are taken in through the burner air intake port 10, mixed in the mixing pipe section, and then blown out to form a flame 12 in the flame hole section 11.

Reference numeral 13 denotes a pressure equalizing chamber or a pressure equalizing passage, which connects the combustion chamber 5 and the nozzle portion 8 in terms of pressure. It is formed by protruding the lower part of No. 14 laterally in a U-shape. That is, this U-shaped protruding part is formed in the pressure equalizing chamber 13, and the nozzle part 8 is positioned in the pressure equalizing chamber 13 by a nozzle holder fixed to the side thereof, and the nozzle part 8 is The nozzle opening is opened near the burner air intake port 10.

Further, the air taken in by the blower 4 through the air filter 16 installed in the intake port 15 opened at the rear surface of the lower part of the casing 1 passes through the air passage 6 provided at the rear surface of the combustion chamber 5, and further passes through the air filter 16 provided at the rear surface of the combustion chamber 5. The air is introduced into air introduction portions 17 provided on the left and right sides of the combustion chamber 5. That is, air introduction part 1
The air introduced into the combustion chamber 7 is guided downward to the burner air intake port 10 and used as primary air, and is also guided to the upper part of the combustion chamber 5 and used as secondary air to achieve complete combustion. There is. For this reason,
The nozzle portion 8 and the burner air intake port 10 are provided inside the partition plate 14.

The hot air that has passed through the combustion chamber 5 is blown into the room through the hot air outlet 7.

Reference numeral 18 designates control devices such as electromagnetic valves and governors, and further includes an operating section 19 and an electronic control box 20. A heat shield plate 21 has the function of partitioning the combustion chamber 5 and thermally protecting the control device 18 and the operating section 19.

Next, the function of the pressure equalization chamber 13 will be explained. here,
The pressure inside the combustion chamber 5 is Pc, and the pressure inside the pressure equalization chamber 13 is
If P'c is set, if the flow caused by the convection fan 3 does not have much influence on the vicinity of the nozzle part 8, then
During steady combustion, both are almost in an equilibrium state,
Pc〓P′c. If the phenomenon of decrease in the pressure inside the combustion chamber 5 is transmitted to the burner air intake port 10 with a delay from the time τ _pff required for the residual gas to cease to be ejected from the nozzle part 8 after the fuel gas is cut off (propagation is at the speed of sound). , let this time be τ _p ), and the pressure decreases while maintaining the relationship Pc<P′c, so the flame 12
The fire will be extinguished almost like a lift, and there will be no backfire.

Pi: fuel gas pressure, Pa: atmospheric pressure, Vp: piping volume from the shutoff valve to the nozzle section, Cd: flow coefficient of nozzle section 8, An: nozzle hole area of nozzle section 8, Rf
(〓Rg): gas constant, Tf: gas temperature, g: gravitational acceleration, γ: gas specific weight, L: pressure propagation distance,
K: Fuel gas specific heat ratio, Tg: Hot air temperature Therefore, by appropriately setting the pressure propagation distance L, the condition of τ _p > τ _pff can be obtained, and Pc <P'c
becomes. In addition, if the pressure propagation distance L is short and an appropriate distance cannot be set, τ _p 〓τ _pff , but in this case, Pc 〓P'c, and Bunsen burner 9 can be used as a normal atmospheric pressure burner. Since it is used, Pc>P′c will never occur, so there is no extinguishing sound and there is no problem.

Therefore, since the combustion chamber 5 and the nozzle section 8 are pressure-communicated via the pressure equalization chamber 13, the same positive pressure Pc is applied to the combustion chamber 5, that is, the flame hole section 11 and the vicinity of the nozzle section 8. Therefore, if a normal burner is used as an atmospheric pressure burner, the same phenomenon will occur as if it were used at atmospheric pressure.
There is no extinguishing sound caused by backfire.

By creating an equal pressure state in this way, even if the flame becomes temporarily unstable for some reason during combustion other than during extinguishing, the relationship Pc = P'c is always maintained, preventing backfire. It is extremely safe without any damage.

In addition, conventionally, primary air was taken in from outside the partition plate 14, but the air that has passed through the air filter 16 is once introduced into the air introduction portions 17 provided on the left and right sides of the combustion chamber 5, and this is the primary air. Since it is used as secondary air, clean air with little dust can be used for combustion, making it possible to always create a stable flame 12.

In addition, although the air blown by the blower 4 has the effect of sucking up the combustion waste gas, the effect of the unstable performance of the blower 4 is that the burner flame opening and the burner air intake are both in the same room, so the effect of suction is more than before. Being less susceptible is also more effective in stabilizing the flame 12, and this also applies when extinguishing the flame.

As explained above, since the pressure equalization chamber is provided in the nozzle section to communicate pressure between the combustion chamber and the nozzle section, extinguishing noise caused by backfire during extinguishing can be generated without reducing the amount of air intake. can be prevented. In addition, if the primary air and secondary air for combustion that have passed through the air filter are introduced into the air inlets provided on the left and right sides of the combustion chamber, clogging of the burner air intake by dust particles will be extremely reduced, and the blower will A stable flame can be formed without affecting performance.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway view showing an embodiment of the gas fan heater according to this invention, and FIG.
It is a sectional view taken along the - line in the figure. DESCRIPTION OF SYMBOLS 1... Casing, 2... Motor, 3... Convection fan, 4... Blower, 5... Combustion chamber, 6... Air duct, 7... Air outlet, 8... Nozzle part, 9... Bunsen burner , 10...burner air intake, 11
...flame hole part, 12 ... flame, 13 ... pressure equalization chamber, 1
4... Partition plate, 15... Intake port, 16... Air filter, 17... Air introduction section, 18... Control equipment, 19... Operation section, 20... Electronic control box, 21... Heat shield plate .

Claims (1)

[Scope of utility model registration request] A gas fan heater in which a combustion chamber opened in a casing is arranged in the casing, and a nozzle part of a Bunsen burner with a flame hole part facing into the combustion chamber faces into the casing, A gas fan heater characterized in that a pressure equalizing passage is provided that communicates pressure between a nozzle portion and the combustion chamber.