JPH0330771B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a forced combustion device that detects combustion conditions and controls combustion.

[Prior art] In combustion devices such as household water heaters, the state of the gas flame is detected by an electrode-type flame rod, and the air-fuel ratio is detected by a thermocouple-type temperature-sensitive member. It is designed to ensure safety during combustion.

[Problems to be solved by the invention] In this way, safety has been attempted, but since unstable thermofluid is used as fuel, in recent years, there has been a need to prepare for the unlikely event of a malfunction. It is hoped that a device that will further enhance safety will be developed.

This invention is a forced combustion device created with a lot of ingenuity to meet this expectation, and it is said that even in the unlikely event that abnormal combustion is caused by a malfunction, it can be avoided, further enhancing safety. The purpose is to demonstrate excellent effects.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a forced combustion device having a group of small craters G and having a horizontally arranged combustion plate 4 whose outer periphery is fitted with a refractory frame 43. , the upper end of the refractory frame 43 is a projecting portion 43a directed toward the center, a heat-sensitive element Th is embedded in a portion located between the projecting part 43a and the combustion plate 4, and the heat-sensitive element Th A configuration is adopted in which the fuel supply to the device is stopped when the refractory frame 43 detects an abnormal temperature rise.

[Operations and Effects of the Invention] The upper end of the refractory frame 43 is a projecting portion 43a directed toward the center, and a heat-sensitive element Th is embedded in a portion located between the projecting portion 43a and the combustion plate 4. .

When abnormal combustion occurs, the heat-sensitive element Th receives a large temperature difference between normal combustion and abnormal combustion, quickly detects abnormal combustion, and stops supplying combustion to the device, thereby ensuring safety.

[Example] Fig. 1 and Fig. 2 show an instantaneous gas water heater incorporating the combustion device of the present invention.

This instantaneous gas water heater includes a combustion box 10 whose interior is a combustion chamber, a forced-air gas combustion device (burner) 1 of a primary air combustion type that completely burns only with primary air, and an upper part of the combustion box 10. A group of plate fins 21 arranged in
a heat exchanger with a combustion box 10 and a burner 1
The water heater case 3 is provided with an outside air inlet 31 in the lower part of the side wall, and a control device 5 for the burner 1.

The combustion box 10 is provided with an exhaust port 10A communicating with the exhaust pipe 11 at the upper end, is open at the lower end, and is provided with a mixing box 14 whose interior is a mixing chamber 1A for fuel gas and air to close the lower end opening. It is being A combustion plate 4 made of ceramic and having a group of small nozzles G is placed on a flange 12 formed at the upper end of the mixing box 14.

A blower 13 for supplying air and a gas pipe 17 having an injection port 15 are attached to the mixing box 14, and constitute the burner 1 described above.

In this embodiment, the small crater group G of the combustion plate 4 has holes of different diameters, and the frequency of vibration generated in each hole during combustion is dispersed to prevent resonance and reduce noise. . The combustion plate 4 is attached as follows. That is, a ceramic refractory frame 43 serving as a flame-holding wall is fitted around the outer peripheral edge of the combustion plate 4. The upper end of this refractory frame 43 forms a projecting portion 43a oriented toward the center. Further, a frame-shaped fixture 45 is fitted onto the fireproof frame 43, and a flange 45C formed thereon is sandwiched between the flange 10B of the combustion box 10 and the flange 12 of the mixing box 14. The fireproof frame 43
A heat-sensitive element Th made of, for example, a bimetal is entirely buried in a portion located between the protruding portion 43a and the combustion plate 4. This heat-sensitive element Th is connected to an electromagnetic main valve (not shown) via a lead wire. For this reason, when an accident such as abnormal combustion occurs, the bimetal, which transmits heat from the flame to the heat-sensitive element Th through the flame-holding wall, operates and closes the main valve. Such abnormal combustion can also be detected by the flame rod 6 and the temperature sensing member 59, which will be described later, but we assume the case where both the flame rod 6 and the temperature sensing member 59 break down for some reason. However, serious accidents can be avoided by using the heat-sensitive element Th. This, so to speak, ensures safety in two stages, and safety is further reinforced. At this time, the projecting portion 4 on the flame-holding wall
In 3a, the temperature actually rises from 700℃ in normal conditions to 750℃ or 800℃ in abnormal conditions, whereas the temperature in the part where the heat-sensitive element Th of the flame-holding wall is located is 600℃ in normal conditions.
The temperature ranges from around 750°C to 800°C during abnormal conditions. In addition, placing the heat-sensitive element Th in the part of the flame-holding wall that is subject to large temperature differences is advantageous in terms of temperature sensing agility, and also because abnormal combustion can be easily detected when the temperature difference is large. Based on. Further, by providing the projecting portion 43a on the flame stabilizing wall, flame stabilization is improved in that the flame does not spread out and is restrained by the flame stabilizing wall. Generally, during combustion,
The flame stabilizing wall around the combustion plate 4 is susceptible to the temperature increasing action and is in a high temperature state. Furthermore, since the flame stabilization of the flame stabilizing wall is improved by the protruding portion 43a, the heat retaining property of the flame stabilizing wall is further improved.

Due to the synergistic effect of this temperature raising effect and the heat retention effect, the flame stabilizing wall reaches a high temperature as shown in the above value, and the heat sensitive element
This is why Th is agile in terms of temperature sensing.

Furthermore, since the surface of the projecting portion 43a that faces the flame has a gently curved shape, it not only has the effect of reinforcing the flame-holding wall, but also allows the projecting portion to form a right angle during molding. In contrast, it is easier to mold, and the flow of thermal fluid is smoother, which is advantageous in terms of thermal efficiency. Further, as the flow of the thermal fluid becomes smoother, the noise generated due to the flow is suppressed.

On the other hand, the control device 5 includes a flame rod 6 consisting of a pair of electrodes 6a and 6b provided on the upper surface of the combustion plate 4 in order to detect the presence or absence of flame in the combustion device 1, a safety valve 51, a flow rate control valve 53, the combustion Two 2 ignition devices installed on the top surface of the plate 4
pole sparkers 55, 57 and the safety valve 51,
A control circuit 50 that controls the flow rate control valve 53, the two-pole sparkers 55, 57, and the motor M of the blower 13, and generates an output that automatically closes the safety valve 51 when the flame rod 6 detects a misfire or ignition error. Be prepared.

Furthermore, a through hole 58 is formed in the center of the combustion plate 4, and the through hole 58 passes through the combustion plate 4 vertically.
A temperature sensing member 59 consisting of a thermocouple is installed within the chamber 8 . For this purpose, the temperature sensing member 59 senses the temperature state of the flame and appropriately adjusts the opening and closing conditions of the air intake to maintain a predetermined air-fuel ratio.

FIGS. 3 and 4 show two other embodiments, one of which uses a heat-sensitive element as shown in FIG.
Th has a heat conducting part Tc made of metal or the like at one end, and one end of this heat conducting part Tc is buried in the flame stabilizing wall so that it is substantially flush with the circumferential surface thereof, and is placed against the combustion plate 4. It is exposed.

In the remaining example, as shown in FIG. 4, in the heat-sensitive element Th, a needle-shaped probing portion P protrudes in the direction of the combustion plate 4 from the heat conducting portion Tc embedded in the flame-holding wall. In this way, the sacrifice of flame stabilization of the flame stabilizing wall can be kept to a minimum compared to the example shown in FIG. It is. in this case,
The probe portion P may also serve as a part of the sparker electrode or flame rod in order to reduce the number of parts.

Incidentally, the small nozzle groups G of the combustion plate 4 are not limited to those with different diameters, but may be composed of ones with the same diameter.
Further, although the fireproof frame 43 is formed separately from the combustion plate 4 in order to improve thermal shock resistance, it is not prohibited to form them integrally. Furthermore, the heat-sensitive element Th may be a dish-shaped thermal response plate, a temperature fuse, or a thermistor. In addition,
The present invention is applicable not only to instantaneous gas water heaters but also to combustion devices in general, and can be implemented with various modifications without departing from the gist of the invention.

[Brief explanation of drawings]

Fig. 1 is a schematic vertical sectional view of the whole, Fig. 2 is a perspective view of the main part, Fig. 3 is a longitudinal sectional view of the main part showing another embodiment, and Fig. 4 is a longitudinal sectional view of the main part showing another embodiment. This is a diagram equivalent to Figure 3. In the figure, 4... combustion plate, G... small crater group, 43...
...Fireproof frame, 43a... Projection, Th... Heat-sensitive element.

Claims (1)

[Claims] 1. In a forced combustion device having a small crater group G and having a horizontally arranged combustion plate 4 whose outer periphery is fitted with a refractory frame 43, the upper end of the refractory frame 43 is directed toward the center. A heat-sensitive element Th is embedded in a portion located between the projecting part 43a and the combustion plate 4, and when the heat-sensitive element Th detects an abnormal temperature rise of the refractory frame 43, the device A forced combustion device characterized by stopping fuel supply to.