TW201741599A - Gas stove the raising amount of the measured temperature is periodically obtained, so that the backfire can be detected according to the raising amount exceeding a backfire threshold value - Google Patents

Abstract

This invention provides a gas stove in which a temperature sensor is utilized for detecting a backfire having a smaller temperature raising amount and capable of avoiding a false detection. A cover member is disposed for covering a mixing tube of a stove burner, and a temperature sensor disposed in the cover member is utilized for measuring a temperature at the inner side. The raising amount of the measured temperature is periodically obtained within a determined defining period, so that the backfire can be detected according to the raising amount exceeding a backfire threshold value. The backfire threshold value is set according to the temperature at the inner side of the cover member. As such, through changing the backfire threshold value, under a situation of the backfire occurring while the temperature at the inner side of the cover member being lower and the measured temperature raising amount being higher, and under a situation of the backfire occurring while the temperature at the inner side of the cover member becoming hotter and the measured temperature raising amount being smaller, the backfire can be detected according to the raising amount exceeding the backfire threshold value. Moreover, the backfire threshold value, under the situation of the temperature at the inner side of the cover member being lower, can be set to be greater than the backfire threshold value under the situation of being hotter, so that the false detection can be avoided.

Description

Gas stove

The present invention relates to a gas furnace having a temperature sensor for detecting abnormal combustion of fuel gas supplied to a burner of a stove.

A gas furnace that burns fuel gas in a stove burner to heat a cooking vessel such as a pan is widely used. The stove burner includes a burner body having a plurality of burner ports and a mixing tube extending from the burner body. The fuel gas supplied through the gas passage is ejected from the nozzle to the open end on the upstream side of the mixing pipe, and flows into the mixing pipe while sucking the primary air for combustion. Then, the mixed gas of the fuel gas and the primary air passing through the mixing tube is ejected from the crater, and when ignited by the spark plug, the mixed gas starts to burn to form a flame on the outside of the crater.

In such a stove burner, abnormal combustion of the supplied fuel gas sometimes occurs. For example, there is a case where, when adjusting (attenuating) the firepower of the stove burner, if the burning speed is faster than the discharge speed of the mixed gas, the flame sneaks from the fire port into the inside of the burner of the stove, and the fuel gas injected from the nozzle is mixed. The phenomenon of continued combustion in the tube (hereinafter referred to as tempering). In addition, when the crater is blocked due to overflow of the broth or the like from the cooking container, the fuel gas leaks from the open end side of the mixing tube, and the flame is ignited by the leaking fuel gas to generate a flame. The phenomenon of diffusion inside the gas furnace (hereinafter referred to as reverse blasting).

Therefore, in order to detect tempering and reverse blasting, it is proposed to provide a thermocouple in advance in the vicinity of the opening end of the mixing tube (Patent Document 1). When tempering or reverse blasting occurs, the thermocouple is heated to generate an electromotive force. Therefore, by shutting off the gas shutoff valve of the gas passage by the electromotive force, abnormal combustion can be stopped. In addition, there is a case where a temperature sensor is used instead of a thermocouple. The temperature rise amount in the fixed period is monitored in advance, and when the temperature rise amount exceeds the threshold value, abnormal combustion is detected, and the gas shutoff valve that closes the gas passage is controlled.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-28428

However, in the gas furnace using the temperature sensor to detect abnormal combustion of the fuel gas as described above, when the supply amount of the fuel gas is set to be small (the firepower of the burner of the stove is small), it is difficult to detect tempering. Such a problem. This is due to the following reasons. First, even if tempering occurs inside the mixing tube, the amount of temperature rise measured by the temperature sensor provided outside the mixing tube is smaller than that of the reverse injection generated from the open end of the mixing tube. Further, the tempering occurs not only in a state where the peripheral temperature of the mixing tube is low shortly after ignition of the burner, but also occurs in a state where the periphery of the mixing tube becomes hot as the burner of the furnace continues to burn. ,because Therefore, especially when tempering occurs in a state of becoming hot, the amount of temperature rise is further reduced and it is difficult to detect tempering.

The present invention has been made in view of the above problems in the prior art, and an object of the invention is to provide a gas furnace capable of detecting tempering with a small temperature rise amount and suppressing erroneous detection using a temperature sensor.

In order to solve the above problems, the gas furnace of the present invention adopts the following structure. That is, a gas furnace equipped with a burner burner including a burner body having a plurality of burner ports and a mixing pipe extending from the burner body, when fuel gas supplied through the gas passage is sprayed from the nozzle to the aforementioned mixing When the open end of the tube is opened, the mixed gas of the fuel gas and the primary air flowing from the open end is ejected from the fire port through the mixing tube, wherein the gas furnace includes a cover that covers the mixing tube and opens the opening The end is accommodated on the inner side; the temperature sensor is attached to the cover to measure the temperature of the inner side of the cover; and the judging unit periodically obtains the rise of the measured temperature of the temperature sensor within a predetermined determination period And determining whether the amount of rise exceeds a predetermined tempering threshold; and the gas shutoff unit cuts off the supply of the fuel gas when the determination unit determines that the amount of rise exceeds the tempering threshold. And a determination reference setting unit that sets the tempering threshold according to a temperature inside the cover.

In the gas furnace of the present invention, by changing the tempering threshold according to the temperature of the inside of the cover, it is possible to return not only in a state where the temperature inside the cover is low, but also after the ignition of the burner is started. When the amount of rise in the measured temperature is large, the amount of rise can be based on the amount of rise When the tempering threshold is exceeded and tempering is detected, and the tempering occurs in a state where the inside of the cover is heated and the furnace burner continues to burn, and the amount of increase in the measurement temperature is small, the amount of increase can be exceeded according to the amount of rise. The tempering threshold is detected and tempering is detected.

In addition, since the tempering threshold in a state where the temperature inside the cover is low is set to be larger than the tempering threshold in a state where the inside of the cover is heated, it is possible to suppress the increase in the measured temperature without tempering. An erroneous detection such as tempering is determined to exceed the tempering threshold.

In the gas furnace of the present invention, the tempering threshold is set not only according to the temperature inside the cover, but also the determination period may be further set according to the temperature inside the cover.

When tempering occurs in a state where the temperature inside the cover is low, the measured temperature rises sharply with the tempering, and it takes time to accurately grasp the amount of rise, whereas when it is inside the cover, it becomes When tempering occurs in a hot state, the measured temperature immediately converges as the tempering rises to a saturated state. Therefore, by changing the determination period according to the temperature of the inner side of the cover, in the state where the temperature inside the cover is low, it is possible to ensure a judgment period sufficient to accurately grasp the rise amount of the measured temperature as the temper rises, by making the occurrence not occur. The difference between the amount of rise during normal combustion of tempering and the amount of rise when tempering occurs increases, and erroneous detection can be suppressed. Further, in a state where the inside of the cover is heated, the tempering can be quickly detected by shortening the determination period.

Further, any one of the mixing tube and the cover of the gas furnace of the present invention may be provided with a heat transfer portion that transfers heat from the mixing tube to the cover by contacting any one of the mixing tube and the cover. .

In this way, when the mixing tube is heated by the tempering, the heat is transmitted to the cover through the heat transfer portion, so that the tempering can be produced as compared with the case where the heat transfer portion is not provided. The raw heat is quickly reflected on the temperature inside the cover (measured temperature of the temperature sensor). As a result, by using the temperature sensor attached to the cover, not only the detection accuracy of the reverse jet can be improved, but also the detection accuracy of the tempering can be improved.

Further, in the gas furnace of the present invention described above, the cover may be formed of a material having a thermal conductivity greater than that of the mixing tube.

In this way, compared with the case where the same material is used to form the cover, the thermal conductivity is improved, and the heat generated by the tempering is easily reacted to the temperature inside the cover, so that it is easy to measure based on the temperature sensor. The amount of temperature rise is used to detect tempering.

According to the above technical means, the present invention provides a gas furnace capable of detecting tempering with a small amount of temperature rise using a temperature sensor and suppressing erroneous detection, thereby performing control of a gas shutoff valve that closes the gas passage.

1‧‧‧ gas stove

2‧‧‧The main body of the stove

3‧‧‧ top board

4‧‧‧burner burner

5‧‧‧Fire support

6‧‧‧Operation knob

10‧‧‧burner body

11‧‧‧Main burner unit

12‧‧‧Deputy Burner Division

13‧‧‧ furnace body

14‧‧‧Main burner head

15‧‧‧Sub burner head

16‧‧‧Main burner crater

17‧‧‧Sub burner burner

18‧‧‧Main burner mixing tube

19‧‧‧Sub burner mixed tube

20‧‧‧Air conditioning unit

21‧‧‧Air conditioning unit

22‧‧‧Air inlet

23‧‧‧Air inlet

24‧‧‧Loading Department

25‧‧‧Loading Department

26‧‧‧Main burner gas piping

27‧‧‧Sub burner gas piping

27a‧‧‧Nozzles

30‧‧ hood

31‧‧‧ fixing screws

32‧‧‧Temperature Sensor

40‧‧‧ gas source piping

41‧‧‧ gas shut-off valve

42‧‧‧Flow regulating valve

50‧‧‧Control Department

Fig. 1 is a perspective view showing the appearance of the gas burner 1 of the present embodiment.

FIG. 2 is a perspective view showing the stove burner 4 mounted in the gas burner 1.

Fig. 3 is a perspective view showing the cover 30 of the present embodiment.

FIG. 4 is an explanatory view showing an example of abnormal combustion of the fuel gas generated in the stove burner 4.

[Fig. 5] is a view showing that the sub-combustor mixing tube 19 is produced based on the amount of rise in the temperature inside the cover. An illustration of an example of a raw temper.

Fig. 6 is a flowchart showing the tempering detection processing executed by the control unit 50 of the present embodiment.

FIG. 7 is a flowchart of the determination criterion setting process executed in the temper detection processing.

FIG. 8 is an explanatory view showing an example of detecting whether or not tempering occurs in the sub-combustor mixing pipe 19 in the gas furnace 1 of the present embodiment in accordance with the tempering detection process.

FIG. 9 is an explanatory view showing an example of detecting whether or not tempering has occurred in the sub-combustor mixing tube 19 in the gas furnace 1 of the first modification.

FIG. 10 is an explanatory diagram for comparing the temperature rise amount ΔT of the inside temperature in the cover during the change determination period.

FIG. 11 is a flowchart of the determination criterion setting process executed by the control unit 50 according to the second modification.

Fig. 1 is a perspective view showing the appearance of a gas burner 1 of the present embodiment. The gas furnace 1 of the present embodiment includes: a cooker body 2 formed in a thin box shape with an upper surface side open; a top plate 3 placed on the stove body 2 and covering the upper surface of the stove body 2; Furnace burners 4R, 4L, the upper portion of which is disposed to protrude from a through hole formed in the top plate 3; and fire supports 5R, 5L which are disposed on the upper surface of the top plate 3 around the burners 4R, 4L to Used to place cooking vessels such as pots.

Further, on the top plate 3, operation knobs 6R, 6L are provided corresponding to the burners 4R, 4L, respectively, and the operation knobs 6R, 6L are used for operation by the user during ignition, firepower adjustment, and the like. When the operation knobs 6R and 6L are pressed downward and rotated in a predetermined direction (counterclockwise direction in this embodiment), the fuel gas is supplied to the stove burners 4R and 4L, and is used by a fuel (not shown). The spark plug is ignited. Thereafter, when the rotation angles of the operation knobs 6R, 6L are changed, the supply amount of the fuel gas is changed, and the heating power of the stove burners 4R, 4L can be adjusted. In addition, the structure and shape of the stove burner 4R on the right side and the stove burner 4L on the left side are basically the same. Therefore, if it is not necessary to particularly distinguish between the right side and the left side, it is only expressed as the stove burner 4 .

FIG. 2 is a perspective view showing the stove burner 4 mounted in the gas burner 1. The stove burner 4 of the present embodiment as shown in the figure is a so-called main and sub-burner having a double structure in which a main burner portion 11 having an annular shape and a sub-combustor portion 12 disposed inside the main combustor portion 11 are provided. The combustor main body 10 constituting the main burner portion 11 and the sub-burner portion 12 includes a furnace body 13, a main burner head portion 14 having a circular shape, a sub-burner head portion 15 having a circular shape, and the like, wherein the furnace body 13 is formed. There is a ring-shaped main burner mixing chamber and a sub-combustor mixing chamber, not shown, the main burner head 14 covers the upper opening of the main burner mixing chamber and is placed on the furnace body 13, and the sub-burner head 15 The upper opening of the sub-combustor mixing chamber is covered and placed on the furnace body 13.

On the lower surface of the outer peripheral wall of the main burner head 14 (the surface placed on the furnace body 13), a plurality of grooves (fire groove) are radially formed with respect to the center of the main burner head portion 14 when When the main burner head 14 is placed on the furnace body 13, a plurality of burner ports 16 are formed by a plurality of burner grooves and the upper surface of the furnace body 13 in communication with the main burner mixing chamber. Similarly, on the lower surface of the outer peripheral wall of the sub-burner head 15, a plurality of crater grooves are radially formed with respect to the center of the sub-burner head 15, and the sub-burner head 15 is placed in the furnace. At the time of the body 13, a plurality of sub-combustor burners 17 communicating with the sub-combustor mixing chamber are formed by the plurality of burner grooves and the upper surface of the furnace body 13.

Further, a main burner mixing pipe 18 communicating with the main burner mixing chamber and a sub-combustor mixing pipe 19 communicating with the sub-combustor mixing chamber are provided extending from the furnace body 13. The main burner mixing pipe 18 and the sub-combustor mixing pipe 19 of the present embodiment are combined with the furnace body 13 by casting using iron. Body formation. An air conditioning device 20 is provided at the open end of the main burner mixing pipe 18 on the side opposite to the furnace body 13, and the opening degree of the air inflow port 22 can be adjusted. When the fuel gas supplied through the main burner gas pipe 26 is injected to the open end of the main combustor mixing pipe 18, it flows into the main combustor mixing pipe 18 while sucking the primary air for combustion from the air inflow port 22. Further, since the mixed gas of the fuel gas and the primary air that has passed through the main burner mixing pipe 18 is supplied to the main combustor mixing chamber and ejected from the main combustor burner 16, the mixing is started when a spark is emitted from a spark plug (not shown). The combustion of the gas forms a flame on the outside of the burner burner 16 of the main burner.

Similarly, an air conditioning device 21 is provided at the open end of the sub-combustor mixing pipe 19 on the side opposite to the furnace body 13, and the opening degree of the air inflow port 23 can be adjusted. Further, the sub-combustor mixing pipe 19 is shorter than the main combustor mixing pipe 18, and the open end of the sub-combustor mixing pipe 19 is located closer to the furnace body 13 than the open end of the main combustor mixing pipe 18. When the fuel gas supplied through the sub-combustor gas pipe 27 is injected to the open end of the sub-combustor mixing pipe 19, it flows into the sub-combustor mixing pipe 19 together with the primary air taken in from the air inflow port 23, and is mixed by the sub-combustor. The mixed gas of the tube 19 is discharged from the sub-combustor burner 17 through the sub-combustor mixing chamber. In the main burner head portion 14 of the present embodiment, a slit for burn-in (not shown) is formed, and the slit for the burn-through is extended from the main burner portion 11 side to the side of the sub-burner portion 12, thereby being used in the sub-burner. The portion 12 starts combustion of the mixed gas to form a flame outside the sub-combustor burner 17 .

Further, in the gas burner 1 of the present embodiment, a cover 30 covering the main burner mixing pipe 18 and the sub-combustor mixing pipe 19 is provided. Fig. 3 is a perspective view showing the cover 30 of the present embodiment. First, the cover 30 in the state before mounting is shown in (a) of FIG. The cover 30 bends the right and left ends of the substantially rectangular upper surface portion of the aluminum flat plate downward by sheet metal working using an aluminum flat plate to form left and right side faces and the front end and the rear end of the substantially rectangular upper surface portion of the aluminum flat plate. Also bent down Folded to form a box shape surrounding the circumference.

On the other hand, the placing portions 24 and 25 placed on the cover 30 are respectively provided on the main burner mixing pipe 18 and the sub-combustor mixing pipe 19 of the present embodiment so as to protrude upward, and the placing portions 24 and 25 are placed. The upper end is formed to be flat. In a state in which the cover 30 is placed on the mounting portion 24 of the main burner mixing tube 18 and the mounting portion 25 of the sub-combustor mixing tube 19, the upper surface portion of the cover 30 is fixed by fastening by a fixing screw 31. Further, the placing portions 24 and 25 of the present embodiment correspond to the "heat transfer portion" of the present invention.

The state after the cover 30 is attached is shown in the table of (b) of FIG. Further, in the drawing, in order to be able to see the main burner mixing tube 18 and the sub-combustor mixing tube 19, the cover 30 is indicated by a broken line through the cover 30. As shown, the open end of the main burner mixing pipe 18 and the open end of the sub-combustor mixing pipe 19 are disposed inside the cover 30. Further, a temperature sensor 32 for measuring the temperature inside is attached to the cover 30, and the temperature sensor 32 of the present embodiment uses a thermistor whose resistance changes according to a change in temperature. In the illustrated example, the tip end of the temperature sensor 32 is inserted through the side surface portion of the cover 30 adjacent to the sub-combustor mixing tube 19, which is adjacent to the outside of the open end of the sub-combustor mixing tube 19.

In the stove burner 4 described above, abnormal combustion of the supplied fuel gas may occur. FIG. 4 is an explanatory view showing an example of abnormal combustion of the fuel gas generated in the stove burner 4. In the figure, a cross section obtained by cutting the sub-combustor mixing tube 19 in a horizontal plane is shown. Further, the cross section of the main burner mixing pipe 18 is omitted, but the basic structure is the same as that of the sub-combustor mixing pipe 19. As described above, the fuel gas is supplied to the sub-combustor mixing pipe 19 through the sub-combustor gas pipe 27, and the sub-combustor gas pipe 27 and the main burner gas pipe 26 are branched from the one gas source pipe 40 on the upstream side.

The gas source pipe 40 is provided with a gas for opening and closing the gas source pipe 40. The body shutoff valve 41 and a flow rate adjusting valve 42 for regulating the flow rate of the fuel gas passing through the gas source pipe 40. The gas shutoff valve 41 is electrically connected to the control unit 50, and is controlled to be opened and closed by the control unit 50. The flow rate adjusting valve 42 is connected to the operation knob 6 on the top plate 3 via a shaft (not shown), and adjusts the flow rate of the fuel gas in accordance with the rotation of the operation knob 6, thereby changing the heating power of the stove burner 4. Further, in the present embodiment, the main burner gas piping 26, the sub-combustor gas piping 27, and the gas source piping 40 correspond to the "gas passage" of the present invention.

When the gas shutoff valve 41 and the flow rate adjusting valve 42 are opened to supply the fuel gas to the sub-combustor gas pipe 27, the fuel gas is injected from the nozzle 27a at the tip end of the sub-combustor gas pipe 27 to the open end of the sub-combustor mixing pipe 19. And, it mixes with the primary air which flows in from the air inlet 23, and it mixes by the sub-combustor mixing tube 19. Further, the combustion which forms the flame on the outside of the sub-combustor burner 17 by igniting the mixed gas discharged from the sub-combustor burner 17 through the sub-combustor mixing chamber is normal combustion. In the same manner, the fuel gas supplied to the main burner gas pipe 26 is injected to the open end of the main combustor mixing pipe 18, but the supply amount of the fuel gas supplied to the main combustor mixing pipe 18 is set to be more than The supply amount of the fuel gas supplied from the sub-combustor mixing pipe 19.

On the other hand, when the sub-combustor burner 17 is clogged due to overflow of the soup or the like from the cooking container placed on the fire support 5, since the mixed gas cannot be ejected from the sub-combustor burner 17, The fuel gas injected from the nozzle 27a of the sub-combustor gas pipe 27 leaks from the air inflow port 23, and when the leaked fuel gas is ignited, as shown in FIG. 4(a), the ejected from the air inflow port 23 occurs. The phenomenon of flame (hereinafter referred to as reverse spray). Further, the reverse injection is generated not only in the air inflow port 23 of the sub-combustor mixing pipe 19, but also in the air inflow port 22 of the main burner mixing pipe 18 when the main burner port 16 is blocked. As above, The open end of the main burner mixing pipe 18 and the open end of the sub-combustor mixing pipe 19 are disposed inside the cover 30, and the heat of the flame diffused by the reverse spray is suffocated inside the cover 30, and therefore, the temperature sensor 32 is heated sharply. The control unit 50 is electrically connected to the temperature sensor 32, and can detect that a reverse spray has occurred based on the measured temperature of the temperature sensor 32. Further, when detecting that the reverse injection has occurred, the control unit 50 forcibly turns off the flame by closing the gas shutoff valve 41.

Further, there is a case where the flame is discharged from the sub-combustor when the discharge speed of the mixed gas is lower than the burning speed when the heating of the stove burner 4 is performed, and the sub-burner head 15 is placed obliquely with respect to the furnace body 13 17 is sneaked into the inside of the stove burner 4, and as shown in FIG. 4(b), the fuel gas injected from the nozzle 27a of the sub-combustor gas pipe 27 is burned in the sub-combustor mixing pipe 19 (hereinafter referred to as back). fire). In particular, in a fuel gas having a high burning rate such as a gas having a large hydrogen component, tempering is likely to occur. Further, the tempering is not limited to being generated in the sub-combustor mixing pipe 19, and the main burner mixing pipe 18 may be similarly generated. Further, once tempering occurs, the combustion is maintained until the supply of the fuel gas is stopped, and the main burner mixing pipe 18 and the sub-combustor mixing pipe 19 are heated, thereby covering the main combustor mixing pipe 18 and the sub-combustor mixing pipe 19 The temperature inside the cover 30 (hereinafter referred to as the inside temperature of the cover) rises. When the control unit 50 detects that tempering has occurred based on the amount of increase in the measured temperature of the temperature sensor 32, the control unit 50 closes the gas shutoff valve 41 to forcibly turn off the flame.

As described above, in the gas burner 1 of the present embodiment, the main burner mixing pipe 18 is provided with the placing portion 24, and the sub-combustor mixing pipe is provided with the placing portion 25, and the cover 30 is placed (contacted). It is fixed in the state of the mounting parts 24 and 25. Therefore, when the main burner mixing pipe 18 and the sub-combustor mixing pipe 19 are heated by tempering, the heat is transmitted to the cover 30 via the placing portions 24 and 25. Thereby, compared with the case where the mounting parts 24 and 25 are not provided, the heat generated by tempering can be made fast. The temperature sensor 32 mounted on the cover 30 is quickly reflected on the temperature in the cover (measured temperature of the temperature sensor 32), and not only the occurrence of the reverse spray but also the occurrence of tempering can be detected. In particular, in the sub-combustor mixing pipe 19, since the supply amount of the fuel gas is smaller than that of the main combustor mixing pipe 18, the amount of heat generation during tempering is also small, and it is difficult to detect the occurrence of tempering. However, by bringing the placing portion 25 into contact with the cover 30 and transferring heat to the cover 30, the amount of increase in temperature measured by the temperature sensor 32 can be increased, and it can be detected that the sub-combustor mixing tube 19 is returned. fire.

Further, the cover 30 of the present embodiment is formed of an aluminum flat plate (thermal conductivity: 236 W/(m.K)), and uses iron in the same manner as the sub-combustor mixing tube 19 and the main burner mixing tube 18 (thermal conductivity: 84 W/ (m.K)) Since the thermal conductivity can be improved as compared with the case where the cover 30 is formed, it is easy to detect the tempering based on the amount of increase in the temperature measured by the temperature sensor 32.

Further, in the gas burner 1 of the present embodiment, the placing portions 24 and 25 are provided in the main burner mixing pipe 18 and the sub-combustor mixing pipe 19, and the placing portions 24 and 25 are in contact with the cover 30, but they may be On the contrary, on the side of the cover 30, a contact portion respectively protruding toward the main burner mixing pipe 18 and the sub-combustor mixing pipe 19 is provided in advance so that the contact portion contacts the main burner mixing pipe 18 and the sub-burner. The state of the mixing tube 19 fixes the cover 30 in advance.

Further, in the gas burner 1 of the present embodiment, the reverse burner and the tempering of the main burner mixing pipe 18 and the sub-combustor mixing pipe 19 are detected by one temperature sensor 32, but a plurality of the plurality of temperature sensors 32 may be provided. Temperature sensor 32. For example, it is also possible to detect the reverse spray and temper at the main burner mixing tube 18 by using the temperature sensor 32 attached to the side portion of the cover 30 on the side of the main burner mixing tube 18, using the cover 30. The reverse spray and tempering at the sub-combustor mixing pipe 19 is detected by the temperature sensor 32 of the side portion on the side of the sub-combustor mixing tube 19. On the other hand, in the present embodiment, one temperature is utilized. When the sensor 32 detects both the main burner mixing tube 18 and the sub-combustor mixing tube 19, the temperature sensor 32 is attached to the side portion of the cover 30 on the side of the sub-combustor mixing tube 19 side in advance. It is easy to detect the tempering at the sub-combustor mixing pipe 19 which is less than the main burner mixing pipe 18 when the tempering heat is small.

FIG. 5 is an explanatory view showing an example of detecting tempering generated in the sub-combustor mixing pipe 19 based on the amount of rise in the temperature inside the cover. In the graph of Fig. 5, the time is taken as the horizontal axis, and the temperature is taken as the vertical axis, and the change in the temperature inside the cover in the case where the burner 4 is normally burned is indicated by a one-dot chain line, which is indicated by a solid line. The change in the temperature inside the hood when the sub-combustor mixing tube 19 is tempered. In addition, the temperature inside the cover is the temperature measured by the temperature sensor 32.

First, an example in which tempering occurs in a state in which the temperature inside the cover 30 is low (for example, 25 ° C) shortly after the ignition of the oven burner 4 is performed is shown in (a) of FIG. 5 . In a state where the temperature inside the cover 30 is low, when the stove burner 4 is normally burned, the temperature inside the cover is gradually increased by the radiant heat from the burner 4 of the stove. On the other hand, when the sub-combustor mixing pipe 19 is tempered, the sub-combustor mixing pipe 19 is heated, whereby the temperature inside the cover 30 covering the sub-combustor mixing pipe 19 is greatly increased as compared with the normal combustion. . Therefore, the temperature increase amount ΔT in the fixed period Δt (for example, 5 minutes) is obtained, and the temperature increase amount ΔT can be exceeded by a predetermined tempering threshold value (larger than the temperature increase amount at the time of normal combustion). It is detected that tempering occurs in the sub-combustor mixing tube 19.

Further, in (a) of FIG. 5, for the sake of comparison, the change in the temperature inside the cover when the main burner mixing tube 18 is tempered is indicated by a broken line. As described above, in the main burner mixing pipe 18 in which the amount of fuel gas supplied is larger than that of the sub-combustor mixing pipe 19, the amount of heat generated during tempering is large, and the amount of rise in the temperature inside the cover is also large, and therefore, the secondary combustion is performed. Compared with the mixing tube 19, it is easy to check The temper is measured.

On the other hand, in (b) of FIG. 5, an example in which tempering occurs in a state in which the inside of the cover 30 is heated by the combustion of the stove burner 4 (for example, 80 ° C) is shown. When the temperature inside the cover 30 of FIG. 5(a) is lower than the state in which the temperature inside the cover 30 is low, even if the sub-combustor mixing tube 19 is tempered, the temperature inside the cover is fixed. The temperature rise amount ΔT in the period Δt is also small. Therefore, sometimes the temperature increase amount ΔT does not exceed the tempering threshold value, so that it is difficult to detect the tempering at the sub-combustor mixing tube 19. In this case, if the tempering threshold is lowered in advance, the tempering does not occur in a state where the temperature inside the cover 30 is low, but the temperature rise amount ΔT is likely to exceed the tempering threshold and is erroneously detected. Get out of the fire. In addition, in FIG. 5(b), the case where the tempering occurs in the main burner mixing pipe 18 is omitted, but the temperature in the cover rises as the tempering of the sub-combustor mixing pipe 19 rises. ΔT is smaller than the temperature increase amount ΔT in which the temperature in the cover rises in accordance with the tempering of the main burner mixing tube 18, so that it is difficult to detect tempering.

Therefore, in the gas furnace 1 of the present embodiment, the control unit 50 performs the tempering detection processing as follows, so that not only the generation of the sub-combustion mixing tube 19 in the state where the temperature inside the cover 30 is low can be detected. The tempering can also detect the tempering generated in the sub-combustor mixing pipe 19 in a state where the inside of the cover 30 is heated.

Fig. 6 is a flowchart showing the tempering detection processing executed by the control unit 50 of the present embodiment. The flaming detection process is started by the user of the gas burner 1 operating the operation knob 6 to ignite the stove burner 4. In the tempering detection processing, first, the temperature inside the hood at the time of ignition of the stove burner 4 is measured by the temperature sensor 32 (step 100). Then, processing for determining the tempering criterion based on the measured inside temperature of the hood (hereinafter referred to as determination criterion setting processing) is executed.

FIG. 7 is a flow of judgment criterion setting processing executed in the temper detection processing Figure. In the judgment reference setting processing, first, it is judged whether or not the temperature inside the cover measured by the temperature sensor 32 is less than 80 ° C (step 130). Then, when the temperature inside the cover is less than 80 ° C (step 130: YES), the tempering threshold is set to the first threshold (23 ° C in the present embodiment) (step 132).

On the other hand, when the inside temperature in the cover is 80 ° C or higher (step 130: NO), it is next determined whether or not the temperature inside the cover is less than 110 ° C (step 134). Then, when the temperature in the cover is 80 ° C or more and less than 110 ° C (step 134: YES), the tempering threshold is set to be smaller than the first threshold (13 ° C in the present embodiment) ( Step 136).

On the other hand, when the inside temperature of the cover is 110° C. or higher (step 134: No), the tempering threshold is set to a third threshold smaller than the second threshold (in the present embodiment, 4° C.) (step) 138). After the tempering threshold is set in accordance with the inside temperature of the hood as described above, the determination reference setting processing of FIG. 7 is ended and the tempering detection processing of FIG. 6 is returned. Further, in the present embodiment, the control unit 50 that sets the tempering threshold value in accordance with the temperature inside the cover corresponds to the "judgment criterion setting means" of the present invention.

In the tempering detection processing, when returning from the determination criterion setting processing (step 102), next, it is determined whether or not a predetermined sampling time has elapsed since the measurement of the temperature inside the hood (15 seconds in this embodiment) (Step 104). In the gas burner 1 of the present embodiment, the temperature inside the cover is measured every time the sampling time elapses, and in the case where the sampling time has not elapsed (step 104: NO), the standby is continued until the sampling time elapses.

Thereafter, when the sampling time has elapsed (step 104: YES), the temperature inside the cover is measured by the temperature sensor 32 (step 106), and it is determined whether the measured temperature inside the cover is a predetermined cutoff temperature (in the present embodiment). The middle is 155 ° C) or more (step 108). When the temperature inside the cover is equal to or higher than the cutoff temperature (step 108: YES), it is determined that the inside of the cover 30 is at a high temperature and is different due to a certain difference. Normally (for example, when the main burner mixing pipe 18 or the sub-combustor mixing pipe 19 is reversely sprayed), it is in a dangerous state, and the gas shutoff valve 41 is closed to forcibly turn off the flame (step 110), and then the process of FIG. 6 is ended. Fire detection processing.

On the other hand, when the inside temperature in the cover is smaller than the cutoff temperature (step 108: NO), the amount of increase in the inside temperature of the cover with respect to the reference time is obtained (step 112). As described above, in the gas furnace 1 of the present embodiment, the temperature inside the cover is measured every time the sampling time (15 seconds) elapses, but the time when the temperature in the cover is measured last time is not used as the reference time, but will be traced back. The time of the predetermined judgment period (5 minutes in the present embodiment) is used as the reference time. In addition, when the elapsed time from the ignition of the stove burner 4 does not reach the determination period, the timing at the time of ignition of the stove burner 4 is used as the reference time.

Then, after the amount of increase in the inside temperature of the hood measured in step 106 is obtained with respect to the inside temperature measured at the reference time, it is determined whether or not the amount of increase in the acquisition exceeds the tempering threshold set at the reference time (step 114). ). As a result, when the amount of rise in the temperature inside the cover exceeds the tempering threshold (step 114: YES), it is determined that tempering has occurred, and the gas shutoff valve 41 is closed to forcibly turn off (step 110), and then the end of FIG. 6 is ended. Tempering detection processing. Further, in the present embodiment, the control unit 50 that determines whether or not the amount of rise in the temperature inside the cover exceeds the tempering threshold corresponds to the "judging means" of the present invention. Further, the control unit 50 that performs the control of closing the gas shutoff valve 41 corresponds to the "gas shutoff unit" of the present invention.

On the other hand, when the amount of rise in the temperature inside the cover does not exceed the tempering threshold (step 114: NO), the determination reference setting process is executed in accordance with the inside temperature measured in step 106 (step 116). In the determination criterion setting processing of this step 116, the same processing as the determination criterion setting processing (see FIG. 7) of the above-described step 102 is executed. That is, according to step 106 The tempering threshold is set to one of the first threshold, the second threshold, and the third threshold in accordance with the measured inside temperature of the hood.

Next, it is judged whether or not the furnace burner 4 is stopped by the operation of the operation knob 6 (step 118). Then, when the combustion is continued (step 118: NO), the process returns to step 104, and after the sampling time elapses, the inside temperature of the cover is measured again, and the subsequent processes are repeated. Therefore, the tempering threshold set in step 116 can be used when tempering is judged in step 114 performed at the time after the elapse of the determination period (5 minutes).

While the tempering is not detected, the furnace burner 4 is stopped by the operation of the operation knob 6 (step 118: YES), and the tempering detection processing of FIG. 6 is ended.

FIG. 8 is an explanatory view showing an example of detecting whether or not tempering occurs in the sub-combustor mixing pipe 19 in the gas burner 1 of the present embodiment in accordance with the tempering detection process. In the graph of Fig. 8, the temperature inside the cover at the reference time is the horizontal axis, and the temperature rise amount ΔT in the determination period (5 minutes) of the temperature inside the cover with respect to the reference time is the vertical axis, and the one-dot chain line is used. The temperature rise amount ΔT in the case where the temperature in the cover is normally burned by the stove burner 4 is indicated by a solid line, and the temperature rise amount ΔT in the case where the temperature in the cover is tempered in the sub-combustor mixing pipe 19 is indicated by a solid line. In addition, the broken line indicates the tempering threshold set based on the inside temperature of the cover at the reference time.

As shown in the figure, when the stove burner 4 is normally combusted and when the sub-combustor mixing tube 19 is tempered, the temperature in the cover is higher than the temperature in the cover at the reference time, and the temperature rise in the cover relative to the reference time is ΔT. The smaller. Further, the higher the temperature inside the cover at the reference time, the temperature rise amount ΔT with respect to the reference time during normal combustion, and the temperature increase amount ΔT with respect to the reference time when the temperature inside the cover is tempered. The smaller the gap.

Therefore, in the gas burner 1 of the present embodiment, as described above, the tempering threshold value is set based on the inside temperature of the cover at the reference time, and if the inside temperature of the cover is less than 80 ° C, the tempering threshold is set to the first threshold value, if the inside of the hood When the temperature is 80° C. or more and less than 110° C., the tempering threshold is set to be smaller than the first threshold, and when the inside temperature is 110° C. or higher, the tempering threshold is set to be smaller than the second threshold. 3 threshold. The first threshold value is set in advance to be larger than the maximum value of the temperature increase amount ΔT at the time of normal combustion and the temperature increase amount ΔT at the time of tempering when the in-hood temperature at the reference time is less than 80° C. The minimum value is small (23 ° C in this embodiment). Similarly, the second threshold value is set to be larger than the maximum value of the temperature increase amount ΔT at the time of normal combustion in the range from 80 ° C to 110 ° C at the reference time and higher than the temperature rise when tempering occurs. The value of the minimum value of the amount ΔT is small (13° C. in the present embodiment), and the third threshold value is set to a temperature increase amount Δ at the time of normal combustion when the in-hood temperature at the reference time is 110° C. or higher. The maximum value of T is large and smaller than the minimum value of the temperature increase amount ΔT at the time of tempering (4 ° C in the present embodiment).

In the gas furnace 1 of the present embodiment, by changing the tempering threshold value according to the temperature inside the cover at the reference time, not only the temperature inside the cover 30 but also the temperature inside the cover 30 can be short after the ignition of the stove burner 4 is performed. When tempering occurs in the state, it is possible to detect tempering in the sub-combustor mixing pipe 19 based on the temperature rise amount ΔT in the inside of the hood during the determination period exceeding the tempering threshold value, and the inside of the hood 30 along with the stove When tempering occurs in a state in which the burner 4 continues to burn and is heated, the tempering in the sub-combustor mixing pipe 19 can be detected based on the temperature increase amount ΔT in the determination period exceeding the tempering threshold value.

In addition, the tempering threshold value on the low temperature side of the cover inner temperature at the reference time (the state in which the temperature inside the cover 30 is low) is set to be higher than the high temperature side of the cover inner temperature at the reference time (the inside of the cover 30 is heated) The tempering threshold of the state, therefore, can suppress the tempering but does not occur The temperature rise amount ΔT exceeds the tempering threshold value and the tempering is detected erroneously.

The gas furnace 1 of the present embodiment described above also has the following modifications. Hereinafter, a modification will be described focusing on differences from the above embodiment. In the description of the modifications, the same components as those in the above-described embodiment are denoted by the same reference numerals, and their description is omitted.

FIG. 9 is an explanatory view showing an example in which the tempering in the sub-combustor mixing tube 19 is detected in the gas furnace 1 of the first modification. In the same manner as in FIG. 8, the temperature inside the cover at the reference time is the horizontal axis, and the temperature increase amount ΔT in the determination period (5 minutes) of the temperature inside the cover with respect to the reference time is taken as the vertical axis. The temperature rise amount ΔT in the case where the temperature inside the cover is normally burned in the furnace burner 4 is indicated by a one-dot chain line, and the temperature in the case where the temperature inside the cover is tempered in the sub-combustor mixing pipe 19 is indicated by a solid line. The amount of rise △T. Further, in the gas furnace 1 of the above-described embodiment, the tempering threshold is set in a step of dividing into three stages (first threshold, second threshold, and third threshold) in accordance with the inside temperature of the reference time. In the gas furnace 1 of the first modification, as shown by a broken line in the figure, the tempering threshold value is linearly set in accordance with the inside temperature of the cover at the reference time.

The straight line illustrated by the broken line in Fig. 9 is obtained by determining the temperature rise amount ΔT at the time of normal combustion and the temperature at the time of tempering for the inside temperature of the cover at each reference time (for example, every 10 ° C). The intermediate value between the rise amounts ΔT is set in consideration of safety, and the threshold value which is lowered from the intermediate value is set, and these threshold values are further approximated by the one-time expression. In the gas furnace 1 of the first modification, the determination criterion setting process (step 102, step 116) in the tempering detection process shown in FIG. 6 is set with reference to the first approximation formula indicated by the broken line in FIG. The tempering threshold corresponding to the temperature inside the hood at the reference time.

In the gas furnace 1 of the first modification, the tempering threshold is changed linearly according to the temperature inside the hood at the reference time, and the tempering threshold is changed in a stepwise manner. In particular, since the tempering threshold can be set to be large on the low temperature side of the inside temperature of the cover at the reference time, it is possible to suppress the occurrence of tempering when the temperature increase amount ΔT exceeds the tempering threshold value without suppressing tempering. Misdetection. On the other hand, since the tempering threshold can be set to be small on the high temperature side of the inside temperature of the cover at the reference time, it is possible to suppress the occurrence of tempering, but the temperature increase amount ΔT does not exceed the tempering threshold and cannot be determined to occur back. Undetected situation like fire.

Further, in the above-described embodiment, the determination period for obtaining the temperature increase amount ΔT of the inside temperature of the cover is set to 5 minutes. However, the present invention is not limited thereto, and the determination period may be set based on the inside temperature of the cover at the reference time. FIG. 10 is an explanatory diagram for comparing the temperature increase amount ΔT of the inside temperature in the cover during the change determination period. In the graph of Fig. 10, the temperature inside the cover at the reference time is the horizontal axis, and the temperature increase amount ΔT in the determination period of the temperature inside the cover with respect to the reference time is the vertical axis, indicating that the temperature inside the cover is mixed in the sub-burner. The temperature rise amount ΔT when the tube 19 is tempered is indicated by a solid line when the determination period is set to 5 minutes, and the case where the determination period is set to 3 minutes by a chain double-dashed line.

As shown in the figure, when the inside temperature in the cover at the reference time is less than 70 ° C, if the determination period is set to 3 minutes, the temperature increase amount ΔT of the inside temperature of the cover becomes substantially constant (peak). In other words, when the temperature in the cover at the reference time is less than 70 ° C, when the sub-combustor mixing tube 19 is tempered, the temperature in the cover will be more than 3 minutes from the occurrence of tempering with the tempering. The time has risen sharply. On the other hand, when the inside temperature in the cover at the reference time is 70° C. or higher, the temperature increase amount ΔT of the inside temperature of the cover when the determination time is set to 5 minutes and the case where the determination time is set to 3 minutes are used. There is no large difference in the temperature rise amount ΔT of the inside temperature of the cover. In other words, when the temperature in the cover at the reference time is 70 ° C or higher, even if the sub-combustor mixing tube 19 is tempered, the temperature inside the cover immediately converges with the increase in the tempering, and the tempering occurs spontaneously. Within 3 minutes Is in a saturated state.

FIG. 11 is a flowchart of the determination criterion setting process (step 102, step 116 of FIG. 6) executed by the control unit 50 according to the second modification. In the determination criterion setting process of the second modification, first, the tempering threshold is set based on the inside temperature measured by the temperature sensor 32 (step 150). In the process of this step 150, the inside temperature of the cover may be set in a stepwise manner according to the tempering threshold value as in the above embodiment, or the inside temperature of the cover may be set in a straight line as in the first modification.

Next, it is judged whether or not the temperature inside the cover measured by the temperature sensor 32 is less than 70 ° C (step 152). When the temperature inside the cover is less than 70 ° C (step 152: YES), the determination period is set to the first period (5 minutes in the second modification) (step 154).

On the other hand, when the inside temperature of the cover is 70° C. or higher (step 152 : No), the determination period is set to be the second period shorter than the first period (3 minutes in the second modification) (step 156) ). After the determination period based on the in-cover temperature setting as described above, the determination criterion setting processing of FIG. 11 is ended, and the tempering detection processing of FIG. 6 is returned. Then, in the process of step 112 performed at the time after the set determination period elapses, the temperature increase amount in the cover temperature with respect to the reference time at which the determination period is set is obtained.

In the gas furnace 1 of the second modification, the determination period is changed by the temperature in the inside of the cover at the reference time, and the low temperature side of the inside of the cover (the temperature inside the cover 30 is low) can be ensured. When the temperature rise amount ΔT during the tempering rise is accurately grasped, the difference between the temperature increase amount ΔT at the time of normal combustion and the temperature increase amount ΔT at the time of tempering becomes large, Can suppress false detection. Further, in the high temperature side of the inside temperature of the cover (in a state where the inside of the cover 30 is heated), the temperature inside the cover immediately saturates as the tempering rises. Therefore, by shortening the determination period, it is possible to quickly detect the occurrence of tempering. .

The gas furnace 1 of the present embodiment and the modifications are described above, but the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the spirit and scope of the invention.

For example, in the above-described embodiment and the modification, the stove burner 4 is a so-called main and sub-burner having a double structure including the main burner portion 11 and the sub-combustor portion 12. However, in a single burner that does not have the sub-burner unit 12, tempering sometimes occurs, and in particular, in a state where the heating power is set weakly (the amount of fuel gas supplied is small), the temperature inside the cover varies with The amount of rise in tempering rise is small, and therefore, the present invention can be preferably applied to detect tempering.

In the second modification, the determination period is set such that the steps are divided into two stages (the first period and the second period). However, the present invention is not limited thereto, and may be based on the temperature inside the cover. The judgment period is set in a straight line.

Claims (4)

A gas burner equipped with a burner burner including a burner body having a plurality of burner ports and a mixing pipe extending from the burner body, wherein fuel gas supplied through the gas passage is sprayed from the nozzle to the mixing tube At the open end, the mixed gas of the fuel gas and the primary air flowing in from the open end is ejected from the fire port through the mixing tube. The gas furnace includes a cover that covers the mixing tube and accommodates the open end. a temperature sensor is attached to the cover to measure the temperature inside the cover; and a determination unit periodically obtains a rise amount of the temperature of the temperature sensor within a predetermined determination period, and Determining whether the amount of rise exceeds a predetermined tempering threshold; and the gas shutoff unit cuts off supply of the fuel gas when the determination unit determines that the amount of rise exceeds the tempering threshold; And the determination criterion setting unit sets the tempering threshold value based on the temperature inside the cover. The gas furnace according to the first aspect of the invention, wherein the determination criterion setting unit sets the tempering threshold value not only based on a temperature inside the cover but also sets the determination period based on a temperature inside the cover. The gas furnace according to claim 1 or 2, wherein any one of the mixing tube and the cover is provided in contact with any one of the mixing tube and the cover to heat The mixing tube is delivered to the heat transfer portion of the cover. The gas burner according to claim 3, wherein the cover is formed of a material having a thermal conductivity greater than a thermal conductivity of the mixing tube.