JP7432475B2 - Gas stove - Google Patents

Description

The present invention relates to a gas stove equipped with a double burner in which two annular burners are coaxially arranged.

Double burners in which two annular burners are coaxially arranged (for example, parent-child burners in which a parent burner and a child burner with a maximum firepower smaller than the parent burner are coaxially arranged) are widely used. There is. In a gas stove equipped with this double burner, fuel gas is supplied to only one burner of the double burner (in the case of a parent-child burner, the child burner), and that burner burns the fuel gas independently (hereinafter referred to as "single burner"). combustion state), and a state where fuel gas is supplied to the two burners of a double burner (the main burner and the child burner in the case of a parent-child burner), and the two burners burn the fuel gas at the same time (hereinafter referred to as the "simultaneous combustion state"). It is possible to switch between. For this reason, in gas stoves equipped with dual burners, one burner (in the case of a parent-child burner, the child burner) burns independently while the required heat power is small, and when a large amount of heat is required, the two burners (parent-child burner) burn independently. In the case of a burner, by switching to a simultaneous combustion state of a parent burner and a child burner, it is possible to achieve a wide range of thermal power (Patent Document 1).

Japanese Patent Application Publication No. 10-073256

However, the above-mentioned conventional gas stove equipped with a double burner has a problem in that it is difficult to evenly heat the bottom of the cooking container. For example, in the case of a parent-child burner, which is a typical double burner, when heating with low heat, the child burner forms a small flame and heats it, so the flame mainly burns around the center of the bottom of the cooking container. The area near the center can be heated, but the area near the outer edge of the bottom of the cooking container cannot be heated. Conversely, when heating with high heat, the main burner and child burner form a flame, but the main burner forms a larger flame than the child burner and mainly burns the area around the outer edge of the bottom of the cooking container. , the vicinity of the outer edge can be sufficiently heated, but the vicinity of the center cannot be sufficiently heated. As a result, the bottom of the cooking container is heated unevenly depending on the heating power, making it difficult to evenly heat the bottom of the cooking container.

This invention was made in order to solve the above-mentioned problems that the conventional technology has, and its purpose is to provide a gas stove that can evenly heat the bottom of a cooking container using a double burner. shall be.

In order to solve the above-mentioned problems, the gas stove of the present invention employs the following configuration. That is,
In a gas stove that heats the bottom of a cooking container, it is equipped with a double burner in which two annular burners are coaxially arranged.
a fuel gas supply passage that supplies fuel gas to the two burners of the double burner;
a gas flow rate adjusting means provided in the fuel gas supply passage and adjusting a total gas flow rate of the fuel gas supplied to the two burners of the double burner;
a set thermal power acquisition means for acquiring a set thermal power set by a user of the gas stove;
control means for controlling the gas flow rate adjusting means so that the total gas flow rate is a gas flow rate corresponding to the set thermal power;
Distribution ratio changing means, which is provided in the fuel gas supply passage downstream of the gas flow rate adjusting means, and changes the distribution ratio of the fuel gas between one burner and the other burner of the double burner. Equipped with and
The control means is characterized in that it is possible to periodically increase or decrease the distribution ratio of the fuel gas while the set thermal power is maintained.

In the gas stove of the present invention, the bottom of the cooking vessel is heated using the double burners arranged coaxially with the two annular burners, and the double burners are provided with a fuel gas supply passage. Fuel gas is supplied from The fuel gas supply passage is equipped with a gas flow rate adjustment means, and the gas flow rate of the fuel gas supplied to the double burner is controlled to a gas flow rate according to the set thermal power set by the user of the gas stove. . The fuel gas is distributed to the two burners of the double burner and then burned in each burner to heat the bottom of the cooking vessel. Here, in the gas stove of the present invention, while the set thermal power is maintained and the fuel gas is combusted in the two burners of the double burner, the distribution ratio of the fuel gas distributed to the two burners is periodically adjusted. It is possible to increase or decrease the amount.

When burning fuel gas in the two burners of a double burner, if the distribution ratio of the fuel gas distributed to the two burners is different, a large flame is formed in one burner and a small flame is formed in the other burner. A flame is formed. Also, as the flame becomes larger, the heating position of the bottom of the cooking vessel moves outward, and as the flame becomes smaller, the heating position moves inward. Thus, a burner forming a large flame heats a location outside the bottom of the cooking vessel, and a burner forming a small flame heats a location inside the bottom of the cooking vessel. Since a large flame has a stronger firepower than a small flame, the bottom of the cooking container is heated mainly at the outer side, which is the position heated by the large flame. In addition, if the difference in the distribution ratio between the two burners is increased, the difference in the size of the flames formed between the two burners will also be increased, and accordingly, the position of the bottom of the cooking vessel that is mainly heated will be on the outside. Move to. Conversely, if you reduce the difference in the distribution ratio between the two burners, the difference in flame size between the two burners will become smaller, and the location at the bottom of the cooking vessel that is primarily heated will move inward. do. For this reason, if the distribution ratio is increased or decreased periodically, the position of the bottom of the cooking container that is mainly heated will shift periodically, making it possible to heat the bottom of the cooking container evenly. Can be done. Further, even if the distribution ratio of fuel gas to the two burners is periodically increased or decreased, it is possible to avoid a situation in which the thermal power for heating the bottom of the cooking container fluctuates in terms of the double burner as a whole.

Moreover, in the gas stove of the present invention described above, one burner of the double burner may be used as a master burner, and the other burner of the double burner may be used as a child burner whose maximum thermal power is smaller than that of the main burner.

Since the parent burner has a greater maximum firepower than the child burners, a larger flame is formed in the parent burner than in the child burners. Therefore, the position where the bottom of the cooking vessel is primarily heated is determined by the position at which the flame of the parent burner heats the bottom of the cooking vessel. If the distribution ratio is changed in the direction of decreasing the fuel gas supplied to the main burner, the flame of the main burner will become smaller, so the position where the bottom of the cooking vessel is mainly heated will be towards the center of the bottom of the cooking vessel. Move to. Conversely, if you change the distribution ratio in the direction of increasing fuel gas to the main burner, the flame of the main burner will become larger, and the position where the bottom of the cooking vessel is mainly heated will shift toward the outer edge of the bottom of the cooking vessel. Moving. For this reason, if the distribution ratio is increased or decreased periodically, the position where the bottom of the cooking container is mainly heated will shift periodically, making it possible to heat the bottom of the cooking container evenly. Can be done.

Moreover, in the gas stove of the present invention described above, a predetermined lower limit gas flow rate may be set for at least one of the two burners of the double burner. When increasing or decreasing the distribution ratio of fuel gas, the distribution ratio is increased or decreased within a range in which the gas flow rate of fuel gas to the burner for which the lower limit gas flow rate is set among the two burners does not fall below the lower limit gas flow rate. You can also do this.

Generally, when the gas flow rate of fuel gas supplied to a burner becomes too small, it becomes difficult to stably burn the fuel gas in that burner. Therefore, for at least one of the two burners of a double burner, the lower limit gas flow rate that allows stable combustion of fuel gas is determined, and the gas flow rate to that burner does not fall below the lower limit gas flow rate. If the distribution ratio is increased or decreased, it becomes possible to stably burn the fuel gas even when the distribution ratio is increased or decreased.

Further, in the gas stove of the present invention described above, the size of the cooking container placed on the trivet may be detected. When the fuel gas distribution ratio is periodically increased or decreased, the gas flow rate of the fuel gas for any burner of the double burner exceeds the upper limit gas flow rate determined according to the size of the cooking vessel. The distribution ratio may be increased or decreased within a certain range.

If you change the distribution ratio to increase the amount of fuel gas to either burner of a double burner, the flame of that burner will become larger, so depending on the size of the cooking vessel, the flame may overflow from the cooking vessel. (a so-called flame overflow situation) may occur. Furthermore, if the size of the cooking container is known, the upper limit gas flow rate (hereinafter referred to as upper limit gas flow rate) that does not cause an overflowing state can be determined in advance. Therefore, the size of the cooking container on the trivet is detected in advance so that the gas flow rate of fuel gas does not exceed the upper limit gas flow rate determined according to the size of the cooking container for any burner of the double burner. By increasing or decreasing the distribution ratio within this range, it is possible to prevent a flame overflow situation from occurring.

In addition, in the gas stove of the present invention described above, when the set thermal power is changed by the user of the gas stove, the fuel gas distribution ratio is maintained at a predetermined standard distribution ratio for a predetermined time, and then the fuel gas distribution ratio is set during that holding time. The distribution ratio may be periodically increased or decreased when the thermal power is not changed.

In this way, it is possible to avoid the situation where the fuel gas distribution ratio increases or decreases while the user of the gas stove is adjusting the set heat power, so the user can easily set the desired set heat power. becomes possible.

Furthermore, in the gas stove of the present invention described above, the distribution ratio may be increased or decreased periodically.

The two burners of a dual burner do not necessarily heat the bottom of the cooking vessel in the same way, even when burning the same gas flow rate of fuel gas. For example, if the two burners in a double burner have different distances to the bottom of the cooking vessel, the burner with a greater distance to the bottom will be less efficient at heating the bottom of the cooking vessel than the burner with a shorter distance. It often happens. Alternatively, if the distances to the trivet are different between the two burners, the distance to the trivet is longer because the burner that is closer to the trivet is more likely to absorb some of the heat from burning fuel gas to the trivet. They are often less efficient at heating the bottom of the cooking vessel than burners. In addition, the two burners of a double burner mainly heat different parts of the bottom of the cooking vessel, so the lower efficiency burner mainly heats the part and the higher efficiency burner mainly heats the part. There is a possibility that a temperature difference may occur between the two. Therefore, the distribution ratio is periodically increased or decreased in such a manner that the time ratio at which the distribution ratio increases with respect to the median value of the increasing or decreasing distribution ratio is different from the time ratio at which the distribution ratio becomes smaller with respect to the median value. This results in a distribution ratio in which the gas flow rate to the less efficient burners heating the bottom of the cooking vessel is greater than the gas flow rate to the more efficient burners (thus a distribution ratio that primarily heats with the less efficient burners). For , the time ratio should be larger, and conversely, the distribution ratio where the gas flow rate to the high efficiency burner is larger than the gas flow rate to the low efficiency burner (therefore, the distribution ratio where heating is mainly performed by the high efficiency burner) For this, the time ratio can be made smaller. As a result, among the two burners of a double burner, the heating time ratio is increased for the part that is heated mainly using the burner with low efficiency, and the ratio of heating time is increased for the part that is heated mainly using the burner with high efficiency. Since the heating time ratio can be made smaller, it is possible to prevent a temperature difference from occurring at the bottom of the cooking container.

Furthermore, in the gas stove of the present invention described above, the total gas flow rate may also be increased or decreased in synchronization with the cycle of increasing or decreasing the distribution ratio.

As mentioned above, the two burners of a double burner differ in the part of the bottom of the cooking vessel that they mainly heat, and furthermore, the two burners may have different efficiencies in heating the bottom of the cooking vessel. be. For this reason, when heating the bottom of the cooking vessel while increasing or decreasing the distribution ratio, the distribution ratio that increases the gas flow rate to the high-efficiency burner (therefore, the distribution ratio that mainly uses the high-efficiency burner for heating) There is a possibility that a temperature difference may occur between the heated part and the part heated with a distribution ratio in which the gas flow rate to the low-efficiency burner is increased (therefore, a distribution ratio in which the low-efficiency burner is mainly used for heating). There is. Therefore, by increasing/decreasing the total gas flow rate in synchronization with the cycle of increasing/decreasing the distribution ratio, when the gas flow rate to the burners with low efficiency increases, the total gas flow rate increases, and the gas flow rate to the high efficiency burners increases. Decrease the total gas flow rate as it increases. In this way, an increase or decrease in the efficiency of heating the bottom of the cooking container can be canceled out by an increase or decrease in the total gas flow rate, so it is possible to prevent a temperature difference from occurring at the bottom of the cooking container.

Moreover, in the gas stove of the present invention described above, two burners of a double burner may be arranged one above the other.

In this way, the size of the double burner can be made smaller than when one of the two burners of the double burner is arranged inside the other burner. As a result, it becomes possible to realize a gas stove that can heat even small cooking containers.

FIG. 1 is a perspective view showing the external shape of a gas stove 1 according to a first embodiment. FIG. 2 is a perspective view showing the rough shape of a parent-child burner 10 mounted on the gas stove 1 of the first embodiment. 2 is an exploded view showing the internal structure of a burner body 11b and a burner cap 20 of the parent-child burner 10. FIG. FIG. 2 is an explanatory diagram showing how fuel gas is distributed to a parent burner 10P and a child burner 10C in accordance with a user's setting firepower in a general gas stove 1 equipped with a parent and child burner 10. FIG. 2 is an explanatory diagram showing the reason why the bottom of the cooking container is unevenly heated depending on the setting heat power in a general gas stove 1 equipped with a parent-child burner 10. FIG. 2 is an explanatory diagram showing the reason why the gas stove 1 of the first embodiment is able to heat the bottom of the cooking container evenly. FIG. 2 is an explanatory diagram showing how the gas stove 1 of the first embodiment supplies fuel gas to the main burner 10P and the child burner 10C according to the set thermal power. The gas stove 1 of the first embodiment is a flowchart of a distribution ratio control process in which the distribution ratio of fuel gas to the main burner 10P and the child burner 10C is controlled according to the set thermal power. FIG. 2 is an explanatory diagram illustrating a manner in which the gas stove 1 of the first embodiment changes the distribution ratio of fuel gas to the main burner 10P and the child burner 10C. FIG. 7 is an explanatory diagram illustrating another manner in which the gas stove 1 of the first embodiment changes the distribution ratio of fuel gas to the main burner 10P and the child burner 10C. FIG. 2 is a perspective view showing the external shape of a gas stove 1 according to a second embodiment. FIG. 7 is an explanatory diagram showing how the gas stove 1 of the second embodiment supplies fuel gas to the main burner 10P and the child burner 10C in consideration of the size of the cooking container. It is a flowchart which shows the first half of the distribution ratio control process performed by the gas stove 1 of 2nd Example. It is a flowchart which shows the latter half of the distribution ratio control process performed by the gas stove 1 of 2nd Example. It is an explanatory view about parent-child burner 10 mounted in gas stove 1 of a 1st modification. It is an explanatory view about parent-child burner 10 mounted in gas stove 1 of a 2nd modification. It is an explanatory view showing how gas stove 1 of a third modification supplies fuel gas to main burner 10P and child burner 10C according to the set thermal power.

A. First example:
FIG. 1 is a perspective view showing the external appearance of a gas stove 1 according to a first embodiment in which a parent-child burner 10 is mounted. The gas stove 1 illustrated in FIG. 1 is a built-in type gas stove 1 that is installed by being fitted into the countertop of a system kitchen (not shown), and is installed to cover the box-shaped stove body 2 and the open top surface of the stove body 2. It is equipped with a top plate 3.

Inside the stove body 2, two parent-child burners 10, in which a parent burner and a child burner (to be described later) are combined in two upper and lower stages, are housed side by side. The upper part protrudes from the formed insertion hole. Further, a trivet 4 is installed on the top plate 3 so as to surround the protruding upper part of each parent and child burner 10, and by placing a cooking container such as a pot on the trivet 4, the cooking container can be opened from below. It is possible to heat with parent-child burner 10. Furthermore, the parent-child burner 10 has a built-in temperature sensor 5 penetrating through the center. The temperature sensor 5 is urged upward by a biasing spring (not shown), and the upper part of the temperature sensor 5 protrudes from the center of the upper surface of the parent-child burner 10. When a cooking container is placed on the trivet 4, the bottom surface of the cooking container pushes down the temperature sensor 5, so that the top end of the temperature sensor 5 comes into contact with the bottom surface of the cooking container, and the temperature of the cooking container is detected. becomes possible. Note that the parent-child burner 10 is one aspect of the "double burner" in the present invention.

Further, a grill door 7 is provided at the front of the gas stove 1, and a grill compartment and grill burner (not shown) are mounted behind the grill door 7. On the right side of the grill door 7, two stove operation buttons 8 are provided corresponding to the two parent and child burners 10, and the user of the gas stove 1 can operate either of the stove operation buttons 8 to control the operation. The parent-child burner 10 can be ignited, extinguished, and the firepower can be adjusted. Further, a grill operation button 9 is provided on the left side of the grill door 7, and by operating the grill operation button 9, the user can ignite or extinguish the grill burner, or adjust the firepower. be able to.

FIG. 2 is a perspective view showing the rough shape of the parent-child burner 10 of this embodiment. As illustrated, the parent-child burner 10 includes a burner body 11 formed by combining sheet metal members, and a burner cap 20 having a substantially cylindrical shape. The burner body 11 includes a burner body 11b having a substantially cylindrical shape, a master mixing tube 12 connected to the burner body 11b, and a child mixing tube 13 having a smaller diameter than the master mixing tube 12 and connected to the burner body 11b. has been done. Further, a burner cap 20 is placed on the burner body 11b. Furthermore, an insertion hole 20h is formed in the center of the burner cap 20, and the temperature sensor 5 described above with reference to FIG. 1 is inserted into this insertion hole 20h.

The burner cap 20 is a member divided into upper and lower parts, and is formed by casting or die-casting using an aluminum alloy or brass. Hereinafter, the upper member constituting the burner cap 20 will be referred to as an upper cap part 21, and the lower member will be referred to as a lower cap part 22. When the upper cap part 21 is placed on the lower cap part 22 as shown, a plurality of upper flame ports 21f are formed on the outer peripheral surface of the upper cap part 21, as shown in an enlarged view in FIG. Furthermore, a plurality of lower flame ports 22f are formed on the outer peripheral surface of the lower cap portion 22. The upper cap part 21 and the lower cap part 22 are assembled at positions where the upper burner ports 21f and the lower burner ports 22f are alternated.

Furthermore, when the burner cap 20 is placed on the burner body 11b, a plurality of small flame ports (hereinafter referred to as child flame ports 22u) are formed between the lower cap portion 22 and the burner body 11b. ing. As will be described later, a space to which the master mixing tube 12 is connected and a space to which the child mixing tube 13 is connected are formed inside the burner body 11b. A child flame opening 22u formed between the lower cap portion 22 and the burner body 11b communicates with a space to which the child mixing tube 13 is connected. Further, an upper burner port 21f formed in the upper cap portion 21 and a lower burner port 22f formed in the lower cap portion 22 communicate with a space to which the parent mixing tube 12 is connected. Therefore, as will be described later, when fuel gas is supplied to the child mixing tube 13, the fuel gas flows out from the child flame port 22u, and when fuel gas is supplied to the parent mixing tube 12, the fuel gas flows out from the top flame port 21f. And it will flow out from the lower flame port 22f.

Fuel gas is supplied to the parent mixing tube 12 and the child mixing tube 13 in the following manner. First, the side of the parent mixing tube 12 that is not connected to the burner body 11b is an open end 12o, and the side of the child mixing tube 13 that is not connected to the burner body 11b is an open end 13o. A gas injection nozzle 43p is provided at a position facing the opening end 12o of the parent mixing tube 12, and a gas injection nozzle 43c is provided at a position facing the opening end 13o of the child mixing tube 13. In the following, the gas injection nozzle 43p provided on the parent mixing pipe 12 side will be referred to as the "parent side gas injection nozzle 43p", and the gas injection nozzle 43c provided on the child mixing pipe 13 side will be referred to as the "child side gas injection nozzle 43p". Sometimes referred to as "injection nozzle 43c." A connection pipe 40p is connected to the parent gas injection nozzle 43p, and a connection pipe 40c is connected to the child gas injection nozzle 43c. These two connection pipes 40p and 40c are branched from the gas supply pipe 40.

When fuel gas is supplied to the gas supply pipe 40, the fuel gas is branched into the connecting pipe 40p and the connecting pipe 40c, and is supplied to the parent side gas injection nozzle 43p and the child side gas injection nozzle 43c. Then, when the fuel gas is injected from the parent-side gas injection nozzle 43p toward the open end 12o of the parent mixing tube 12, the fuel gas flows into the parent mixing tube 12 while drawing in surrounding air due to the ejector effect. After being mixed with air in the mixing tube 12, it flows out from the upper burner port 21f and the lower burner port 22f. Similarly, when fuel gas is injected from the child-side gas injection nozzle 43c toward the open end 13o of the child mixing tube 13, the fuel gas flows into the child mixing tube 13 while drawing in surrounding air due to the ejector effect. After being mixed with air in the child mixing tube 13, it flows out from the child flame opening 22u.

Further, a gas flow rate control valve 41 is installed in the middle of the gas supply pipe 40 to adjust the gas flow rate of the fuel gas. Furthermore, a resistance adjustment valve 42p for adjusting the passage resistance of the connecting pipe 40p is installed in the middle of the connecting pipe 40p that supplies fuel gas to the parent mixing pipe 12, and supplies fuel gas to the child mixing pipe 13. A resistance adjustment valve 42c is installed in the middle of the connecting pipe 40c to adjust the passage resistance of the connecting pipe 40c. Hereinafter, the resistance adjustment valve 42p attached to the connection pipe 40p will be referred to as the "parent side resistance adjustment valve 42p", and the resistance adjustment valve 42c attached to the connection pipe 40c will be referred to as the "child side resistance adjustment valve 42c". Furthermore, the resistance adjustment valve 42p and the resistance adjustment valve 42c may be collectively referred to simply as the resistance adjustment valve 42. Further, as the gas flow rate control valve 41, the parent side resistance control valve 42p, and the child side resistance control valve 42c, various well-known valves capable of adjusting the valve opening degree continuously or in multiple steps may be used. However, in the first embodiment, a flow control valve is used which is driven by a stepping motor and whose opening degree can be finely adjusted.

In this embodiment, the gas supply pipe 40, the connection pipe 40p, and the connection pipe 40c correspond to the "fuel gas supply passage" in the present invention. Further, the flow rate of the fuel gas flowing through the gas supply pipe 40 corresponds to the "total gas flow rate" in the present invention, and the gas flow rate control valve 41 provided in the gas supply pipe 40 corresponds to the "gas flow rate control means" in the present invention. corresponds to Furthermore, the resistance adjustment valve 42 (namely, the resistance adjustment valve 42p and the resistance adjustment valve 42c) corresponds to the "distribution ratio changing means" in the present invention.

Further, a spark plug 30 and a flame sensor 32 are provided in the burner body 11 in close proximity to the outer circumferential surface of the burner body 11b, and the spark plug 30 and the flame sensor 32 are connected to the control section 50. Further, above the spark plug 30, an ignition target 31 is provided to protrude from the outer peripheral surface of the burner cap 20. The control unit 50 fully closes the parent resistance control valve 42p provided on the connection pipe 40p, and then opens the gas flow control valve 41 while discharging sparks from the ignition plug 30 toward the ignition target 31. When this happens, fuel gas flows out from the child flame port 22u, and the fuel gas is ignited to start combustion. The flame sensor 32 is capable of detecting the flame generated in the child flame port 22u, and the control unit 50 recognizes that combustion has started by detecting the flame in the child flame port 22u. Can be done. Furthermore, when the parent side resistance adjustment valve 42p is opened in this state, fuel gas also flows out from the upper flame port 21f and the lower flame port 22f, and the fuel gas is ignited by the flame of the child flame port 22u. , combustion is also started at the upper burner port 21f and the lower burner port 22f. Further, the stove operation button 8 and the grill operation button 9 are connected to the control section 50. For this reason, the control unit 50 is able to obtain the set thermal power set by the user of the gas stove 1 using the stove operation button 8 or the grill operation button 9. Then, the control unit 50 controls the gas flow rate adjustment valve 41 so that the gas flow rate of the fuel gas flowing through the gas supply pipe 40 becomes a gas flow rate corresponding to the set thermal power. Note that the control unit 50 of this embodiment acquires the set thermal power set to the stove operation button 8 and controls the operation of the gas flow rate control valve 41 and the resistance control valve 42, so that It corresponds to "set firepower acquisition means" and "control means".

As shown in FIG. 2, the upper burner port 21f and the lower burner port 22f are set to have a larger opening area than the child burner port 22u. Furthermore, the parent mixing tube 12 that communicates with the upper burner port 21f and the lower burner port 22f inside the burner body 11 is also formed to have a large diameter, as does the child mixing tube 13 that communicates with the child burner port 22u. . Therefore, the upper burner port 21f and the lower burner port 22f can combust a larger amount of fuel gas than the child burner port 22u, thereby generating large thermal power. Therefore, the parent-child burner 10 burns fuel gas at the secondary burner port 22u while the required thermal power is small, and when large thermal power is required, the fuel gas is burned at the upper burner port 21f and the lower burner port 22f. It is used in a way that causes it to burn. For this reason, the part of the child burner 22u in the parent-child burner 10 is called the "child burner 10C", and the part of the upper burner 21f and the lower part 22f in the parent-child burner 10 is called the "parent burner 10P". It is called.

As shown in FIG. 2, in the parent-child burner 10 of this embodiment, the parent burner 10P and the child burner 10C are arranged on the same axis in two stages, upper and lower. The burners 10C do not necessarily have to be arranged in two stages, upper and lower. For example, the parent-child burner 10 may be a parent-child burner 10 in which a child burner 10C having a smaller diameter than the parent burner 10P is arranged inside the annular parent burner 10P. . Further, the parent-child burner 10 of the present embodiment has a two-tiered burner port by arranging the upper burner port 21f and the lower burner port 22f in a staggered manner in the parent burner 10P, but the present invention is not limited to this. , the upper burner port 21f and the lower burner port 22f of the main burner 10P may be arranged in a vertically aligned state to form a single-stage burner port.

FIG. 3 is an exploded view showing the internal structure of the burner body 11b and burner cap 20 of the parent-child burner 10. As illustrated, the upper end of the approximately cylindrical burner body 11b is bent inward to form an annular mounting surface 11a on which the burner cap 20 is mounted. Further, a cylindrical central cylinder 14 is provided upright inside the burner body 11b, and an annular mixing chamber 16 is formed between the burner body 11b and the central cylinder 14 to which the mixed gas is supplied. has been done.

Furthermore, a substantially cylindrical partition cylinder 15 is provided between the burner body 11b and the central cylinder 14, and the mixing chamber 16 is separated from the space inside the partition cylinder 15 by this partition cylinder 15. and a space outside the partition cylinder 15. The space inside the partition cylinder 15 becomes a parent mixing chamber 16p, which will be described later, and the space outside the partition cylinder 15 becomes a child mixing chamber 16c, which will be described later. The partition cylinder 15 is formed of a sheet metal member like the burner body 11b, and after the upper end side of the cylindrical shape is bent inward, the inside side is bent downward to form a short cylindrical fitting surface 15a. is formed.

As described above, the burner cap 20 includes the upper cap part 21 and the lower cap part 22. The lower cap part 22 is placed on the mounting surface 11a of the burner body 11b, and the upper cap part 21 is placed on the lower cap portion 22. As shown in the figure, the lower cap portion 22 is a substantially annular member, and a cylindrical partition wall tube 22a is vertically provided downward from the inner edge portion. Furthermore, a plurality of lower grooves 22b are formed radially with respect to the center of the lower cap portion 22 on the lower surface of the outer edge portion (the surface that contacts the mounting surface 11a of the burner body 11b).

Further, an upward cylindrical wall 22c that protrudes upward in a cylindrical shape is provided on the outer edge portion of the lower cap portion 22, and an upward cylindrical wall 22c is provided on the upper end surface of the upward cylindrical wall 22c. A plurality of lower grooves 22d are formed radially from the center of the wall 22c. Note that the lower groove 22d is not provided at a position facing the plurality of claws of the trivet 4. In addition, an ignition target 31 is protruded from the outer peripheral surface of the upward cylindrical wall 22c at a position above the spark plug 30 described above.

On the other hand, the upper cap portion 21 is formed in an annular shape, and has a cylindrical inner tube (not shown) extending downward from the inner edge portion. Further, a cylindrical downward cylindrical wall 21a is provided downward from the outer edge portion, and the lower end surface of the downward cylindrical wall 21a is radially disposed with respect to the center of the downward cylindrical wall 21a. A plurality of upper grooves 21b are formed. Note that the upper groove 21b is not provided at a position facing the plurality of claws of the trivet 4, similarly to the lower groove 22d described above.

The upper cap part 21 and the lower cap part 22 are assembled in such a way that the upper groove 21b of the upper cap part 21 and the lower groove 22d of the lower cap part 22 do not overlap. Therefore, when the burner cap 20 is formed by combining the upper cap part 21 and the lower cap part 22, the upper flame port 21f is formed in the part where the upper groove 21b opens on the outer peripheral surface of the downward cylindrical wall 21a. A lower flame port 22f is formed in a portion where the lower groove 22d opens to the outer circumferential surface of the upward cylindrical wall 22c (see FIG. 2). Moreover, since the upper groove 21b and the lower groove 22d are positioned so as not to overlap, the upper flame outlet 21f and the lower flame outlet 22f are formed at alternate positions.

When placing the burner cap 20 on the burner body 11b, first insert the partition tube 22a that hangs downward from the inner edge of the lower cap part 22 into the inside of the fitting surface 15a of the partition tube 15. At the same time, the burner cap 20 is lowered while inserting an inner cylinder (not shown) hanging downward from the inner edge portion of the upper cap part 21 into the inside of the central cylinder body 14. Then, the lower groove 22b formed on the lower surface of the outer edge portion of the lower cap portion 22 comes into contact with the mounting surface 11a of the burner body 11b, and the burner cap 20 is mounted on the burner body 11b.

When the burner cap 20 is placed on the burner body 11b, the partition cylinder 22a of the lower cap part 22 fits into the fitting surface 15a of the partition cylinder 15, and the inner cylinder (not shown) of the upper cap part 21 fits into the center cylinder. It is in a state where it fits into the inner peripheral surface of the upper part of the body 14. As a result, a child mixing chamber 16c surrounded by the partition cylinder 15, the burner body 11b, and the lower cap part 22 is formed on the outside of the partition cylinder 15. This child mixing chamber 16c communicates with the child mixing tube 13. Further, inside the partition cylinder 15, a parent mixing chamber 16p is formed, which is surrounded by the central cylinder 14, the partition cylinder 15, the partition cylinder 22a, and the upper cap part 21. This parent mixing chamber 16p communicates with the parent mixing tube 12.

The two stove operation buttons 8 (see FIG. 1) mounted on the front of the gas stove 1 are connected to the control section 50 shown in FIG. A valve 41 is also connected. When the user of the gas stove 1 sets the thermal power used for cooking by operating the stove operation button 8, the control unit 50 acquires the thermal power (set thermal power) set by the user. Then, the fuel gas is combusted in the parent-child burner 10 by controlling the operations of the gas flow rate control valve 41 and the resistance control valve 42 (namely, the resistance control valve 42p and the resistance control valve 42c) according to the set thermal power.

For example, when the thermal power set by the user is small, the gas flow rate control valve 41 is controlled to reduce the gas flow rate of the fuel gas passing through the gas supply pipe 40, and the resistance control valves 42p and 42c are controlled. Thus, the fuel gas from the gas supply pipe 40 is supplied to the child burner 10C, but not to the main burner 10P. By doing so, it is possible to control the child burner 10C to a state in which the fuel gas is combusted alone (independent combustion state). When the set thermal power is large, the gas flow rate control valve 41 is controlled to increase the gas flow rate of the fuel gas passing through the gas supply pipe 40, and the resistance control valve 42p and the resistance control valve 42c are controlled to increase the gas flow rate. Fuel gas from the supply pipe 40 is supplied to the main burner 10P and the child burner 10C. By doing so, the main burner 10P and the child burner 10C can be brought into a state in which the fuel gas is combusted at the same time (simultaneous combustion state). In this way, by switching between the independent combustion state of the child burner 10C and the simultaneous combustion state of the main burner 10P and the child burner 10C, a wide range of firepower from small to large firepower can be achieved depending on the firepower set by the user. can be realized.

However, simply switching the single combustion state of the child burner 10C to the simultaneous combustion state of the main burner 10P and the child burner 10C makes it possible to cook with high heat, but it does not heat the bottom of the cooking container evenly. The problem is that it cannot be done. Therefore, in the gas stove 1 of the first embodiment, while the main burner 10P and the child burner 10C are burning fuel gas at the same time, the distribution ratio for distributing the fuel gas between the main burner 10P and the child burner 10C is periodically increased or decreased. By doing so, the bottom of the cooking container is heated evenly. In preparation for explaining why this is possible, we will explain how fuel gas is distributed to the parent burner 10P and child burner 10C in a general gas stove 1 equipped with parent and child burners 10, depending on the heating power set by the user. do.

FIG. 4 is an explanatory diagram showing how fuel gas is supplied to the parent burner 10P and the child burner 10C according to the heating power set by the user in a general gas stove 1 equipped with the parent and child burners 10. The horizontal axis in the figure represents the gas flow rate of the fuel gas supplied to the slave burner 10C, and the vertical axis in the figure represents the gas flow rate of the fuel gas supplied to the main burner 10P. In this way, if the gas flow rate to the child burner 10C and the gas flow rate to the parent burner 10P are set on orthogonal coordinate axes, the operating state of the parent and child burner 10 can be represented by coordinate points, and as a result of changes in the set thermal power. Changes in operating conditions can be expressed as movement of coordinate points. In the general gas stove 1, as the user increases the set firepower, the coordinate points move as follows.

Point a shown in FIG. 4 represents the coordinate point when the set firepower is the minimum. As described above, in the parent-child burner 10, the child burner 10C burns the fuel gas independently at low thermal power, so the gas flow rate to the parent burner 10P becomes zero. Further, the child burner 10C has a lower limit gas flow rate (lower limit gas flow rate) that allows stable combustion of the fuel gas. Therefore, when the set thermal power is the minimum, the operating state of the parent and child burners 10 is the coordinate point represented by point a where the gas flow rate of the parent burner 10P is 0 and the gas flow rate to the child burner 10C is the lower limit gas flow rate. becomes. In addition, in FIG. 4, the lower limit gas flow rate of the slave burner 10C is indicated by a chain line. Furthermore, for the parent burner 10P, there is also a lower limit gas flow rate at which fuel gas can be stably combusted, and in FIG. 4, the lower limit gas flow rate for the parent burner 10P is indicated by a chain double-dashed line.

When the user increases the set thermal power from the minimum thermal power, the gas flow rate (total gas flow rate) passing through the gas flow rate control valve 41 is increased while keeping the gas flow rate to the main burner 10P at 0. Therefore, the gas flow rate to the child burner 10C increases by the amount that the total gas flow rate increases, and the coordinate point representing the operating state of the parent and child burner 10 is the coordinate point in FIG. Move to. In FIG. 4, the thick solid arrow extending rightward from point a represents the movement of the coordinate point as the set firepower increases.

When the thermal power set by the user exceeds a predetermined threshold thermal power, the state is switched from the independent combustion state of the child burner 10C to the simultaneous combustion state of the main burner 10P and the child burner 10C. In FIG. 4, dotted arrows indicate how the parent-child burner 10 switches from the independent combustion state of the child burner 10C to the simultaneous combustion state of the parent burner 10P and the child burner 10C. Point b, which is the starting point of the arrow, represents a state of independent combustion by the child burner 10C, and point c, which is the end point of the arrow, represents a state of simultaneous combustion by the main burner 10P and child burner 10C.

Here, point c has the following coordinates. First, the gas flow rate of the fuel gas to the child burner 10C is the lower limit gas flow rate of the child burner 10C. Further, the total gas flow rate, which is the sum of the gas flow rate to the child burner 10C and the gas flow rate to the parent burner 10P, is equal to the gas flow rate to the child burner 10C at point b. Therefore, even if there is a jump from point b to point c, the thermal power of the parent and child burners 10 as a whole increases or decreases by simply distributing the fuel gas that was previously supplied to the child burner 10C to the parent burner 10P and the child burner 10C. There's nothing to do. Note that the gas flow rate to the parent burner 10P at point c is larger than the lower limit gas flow rate of the parent burner 10P indicated by the two-dot chain line in FIG. 4, so the parent burner 10P stably supplies fuel gas at point c. It is possible to burn it.

In addition, in the general parent-child burner 10, the resistance adjustment valve 42c (see FIG. 2) is not mounted on the connection pipe 40c on the child side, and the resistance adjustment valve 42p (see FIG. 2) is not installed on the connection pipe 40p on the parent side. ) instead, a simple on-off valve is installed. If the on-off valve mounted on the connection pipe 40p on the parent side is closed, the child burner 10C can achieve an independent combustion state, and if the on-off valve is opened, the main burner 10P and the child burner A simultaneous combustion state of 10C can be realized. The fuel gas distribution ratio between the main burner 10P and the child burner 10C in the simultaneous combustion state is determined by the passage resistance from the parent side connection pipe 40p to the main burner 10P and from the child side connection pipe 40c to the child burner 10C. It has a fixed distribution ratio determined by the ratio between the path resistance and the path resistance.

Note that hereinafter, the distribution ratio will be expressed as the ratio of the gas flow rate to the child burner 10C in the total gas flow rate. For example, at point c in FIG. 4, about 15% of the total gas flow rate is supplied to the child burner 10C, so the distribution ratio at this time is 0.15. Moreover, this method of expressing the distribution ratio focuses on the child burner 10C and expresses the ratio of the gas flow rate distributed to the child burner 10C. However, the method of expressing the distribution ratio by focusing on the child burner 10C is not necessarily common. Therefore, when the total gas flow rate is 10, the distribution ratio can be expressed by the ratio of "gas flow rate to main burner 10P" and "gas flow rate to child burner 10C", which can be used in combination as necessary. shall be. For example, when a distribution ratio of 0.15 is expressed as a ratio of "gas flow rate to the main burner 10P" and "gas flow rate to the child burner 10C", it becomes 8.5:1.5.

When the user further increases the set thermal power after switching to the simultaneous combustion state of the main burner 10P and the child burner 10C, the gas flow rate passing through the gas flow rate control valve 41 is increased. As a result, the gas flow rates of the main burner 10P and the child burner 10C increase simultaneously. In the conventional parent-child burner 10, the distribution ratio of fuel gas to the parent burner 10P and child burner 10C is determined by the passage resistance from the parent side connection pipe 40p to the parent burner 10P and from the child side connection pipe 40c to the child burner 10C. It is determined by the ratio between the path resistance and the path resistance. Therefore, even while the gas flow rates of the main burner 10P and the child burner 10C increase simultaneously, the distribution ratio of fuel gas remains the same as the distribution ratio at point c (typically, the distribution ratio is 0.15). . Then, as the heating power set by the user increases, the gas flow rate of the main burner 10P and the child burner 10C increases while maintaining the distribution ratio, until the gas flow rate of the main burner 10P reaches the maximum flow rate at point d. When this temperature is reached, the parent-child burner 10 reaches its maximum firepower state. In FIG. 4, the thick solid arrow extending from point c to point d represents how the coordinate point moves on a straight line with a distribution ratio of 0.15 as the set thermal power increases.

In a conventionally used general gas stove, a parent-child burner 10 is operated in the manner shown in FIG. For this reason, the portions of the bottom of the cooking container that are heated by the parent and child burners 10 are unevenly distributed, and the unevenly heated portions change depending on the user's setting of the heating power. The problem arises that it is difficult to heat and cook the food according to the instructions. The reasons why these problems occur are as follows.

FIG. 5 is an explanatory diagram showing how a common gas stove equipped with a parent-child burner 10 heats the bottom of a cooking container. FIG. 5(a) shows a state in which heating is performed with a small thermal power corresponding to the vicinity of point c in FIG. 4. As described above using FIG. 4, near point c, the gas flow rate to the main burner 10P and the child burner 10C is small, so a small flame is formed in the main burner 10P and the child burner 10C. Therefore, as shown in FIG. 5(a), the flame Fp of the main burner 10P and the flame Fc of the child burner 10C cannot heat the vicinity of the outer edge of the bottom of the cooking container, but only heat the vicinity of the center. It turns out.

FIG. 5(b) shows a state in which heating is performed at a medium heating power corresponding to the midpoint between point c and point d in FIG. When the set thermal power is increased, the gas flow rate supplied to the main burner 10P and the child burner 10C increases, so that the flame Fp of the main burner 10P and the flame Fc of the child burner 10C become larger. Therefore, when changing from a low heat power state to a medium heat power state, the position heated by the flame Fp of the main burner 10P moves from near the center to the outside. In addition, the flame Fc of the child burner 10C also becomes large, but the size of the flame Fc of the child burner 10C is smaller than the flame Fp of the parent burner 10P, so the position where the bottom of the cooking vessel is heated is mainly from the parent burner 10P. This is the position heated by the flame Fp.

FIG. 5(c) shows a state in which heating is performed with a large thermal power corresponding to the vicinity of point d in FIG. 4. When the set thermal power is increased to near the maximum thermal power, the gas flow rate to the main burner 10P and the child burner 10C further increases, so that the flame Fp of the main burner 10P and the flame Fc of the child burner 10C also become larger. For this reason, when the high thermal power is set, the position heated by the flame Fp of the main burner 10P moves further outward. At this time, the flame Fc of the child burner 10C also becomes large, but the position where the bottom of the cooking vessel is heated is mainly the position heated by the flame Fp of the main burner 10P. In the example shown in FIG. 5(c), the flame Fp of the main burner 10P heats the outer edge portion of the bottom of the cooking container.

As described above, in conventional general gas stoves, the size of the flame formed in the main burner 10P and the child burner 10C changes depending on the setting firepower set by the user, and when the size of the flame changes, the main burner The position where the 10P flame Fp heats the bottom of the cooking container changes. Therefore, no matter what heat power is set, a portion of the bottom of the cooking container will be heated. For these reasons, it is difficult to heat the bottom of the cooking container evenly with conventional gas stoves. In addition, not only is the bottom of the cooking container partially heated, but the heating position moves depending on the set firepower.In this respect, conventional gas stoves need improvement. It is thought that there are points. On the other hand, in the gas stove 1 of the first embodiment, by distributing the fuel gas to the main burner 10P and the child burner 10C as follows, it is possible to evenly heat the bottom of the cooking container. ing. Furthermore, since the bottom of the cooking container can be heated evenly, there is naturally no possibility that the heated position will shift depending on the set heating power.

FIG. 6 is an explanatory diagram showing the principle by which the gas stove 1 of the first embodiment can evenly heat the bottom of the cooking container. FIG. 6 shows how flames are formed in the main burner 10P and the child burners 10C when the distribution ratio of fuel gas is varied while keeping the total gas flow rate to the main burner 10P and the child burners 10C constant. represents.

The white circles shown in FIG. 6 are set when the fuel gas distribution ratio is around 0.1 (that is, "gas flow rate to main burner 10P": "gas flow rate to slave burner 10C" = 9:1). It represents the state of being. When the distribution ratio is set to around 0.1, about 90% of the fuel gas of the total gas flow rate is supplied to the parent burner 10P, so a large flame Fp is formed in the parent burner 10P. In FIG. 6, above the white circle mark, it is shown that a large flame Fp is formed in the main burner 10P.

The diagonally shaded circles in FIG. 6 indicate a fuel gas distribution ratio of 0.3 (i.e., "gas flow rate to main burner 10P": "gas flow rate to slave burner 10C" = 7:3). ) represents the case where it is set near. When the distribution ratio is set to around 0.3, the gas flow rate to the parent burner 10P is reduced compared to when it is set to around 0.1, so the flame Fp formed in the parent burner 10P becomes smaller. On the other hand, since the gas flow rate to the child burner 10C increases, the flame Fc of the child burner 10C becomes larger. However, even in this case, the main burner 10P is supplied with more than twice as much fuel gas as the child burner 10C, so a larger flame is formed in the main burner 10P than in the child burner 10C. Above the diagonally shaded circle in FIG. 6, a flame Fp formed in the main burner 10P and a flame Fc formed in the child burner 10C are shown when the distribution ratio is set to around 0.3. ing.

The black circles shown in Fig. 6 are set when the fuel gas distribution ratio is around 0.5 (that is, "gas flow rate to main burner 10P": "gas flow rate to child burner 10C" = 5:5). This represents the case where When the distribution ratio is set to around 0.5, the gas flow rate to the parent burner 10P is further reduced than when the distribution ratio is 0.3, so the flame Fp formed in the parent burner 10P is further reduced. Further, since substantially the same amount of fuel gas is supplied to the main burner 10P and the child burner 10C, a flame Fc of substantially the same size as the main burner 10P is also formed in the child burner 10C. In FIG. 6, a flame Fp formed in the main burner 10P and a flame Fc formed in the child burner 10C are shown above the black circle when the distribution ratio is set to around 0.5.

As is clear from FIG. 6, when the distribution ratio is decreased, the heating position at the bottom of the cooking vessel moves outward, and when the distribution ratio is increased, the heating position is moved inward. From this, it is possible to evenly heat the bottom of the cooking container by periodically changing the distribution ratio to the main burner 10P and child burner 10C while heating at the set firepower set by the user. It is thought that it will become. For example, as shown by the thick dashed arrow in Figure 6, by gradually increasing the distribution ratio from around 0.1 to around 0.5, the heating position of the bottom of the cooking container can be changed from around the outer edge to around the center. It can be moved slowly up to. After that, as shown by the thick dashed-dotted arrow in FIG. can be moved slowly. By heating the bottom of the cooking container while changing the distribution ratio in this way, it becomes possible to heat the bottom evenly. Furthermore, even if the distribution ratio is changed, the total gas flow rate that is the sum of the gas flow rate of the parent burner 10P and the gas flow rate of the child burner 10C does not change, so the thermal power of the parent and child burner 10 does not change. The above is the basic idea that enables the gas stove 1 of the first embodiment to evenly heat the bottom of the cooking container.

In addition, in FIG. 6, the reason why the distribution ratio is not made larger than 0.5 is that when the distribution ratio becomes 0.5, the size of the flame Fp formed in the main burner 10P and the size of the flame Fp formed in the child burner 10C are different. This is because the size of the flame Fc becomes almost the same. That is, in a range where the distribution ratio is smaller than 0.5, the flame Fp of the main burner 10P is larger than the flame Fc of the child burner 10C, so the heating position at the bottom of the cooking container is mainly determined by the flame Fp of the main burner 10P. has been done. Therefore, the smaller the flame Fp of the parent burner 10P is made by increasing the distribution ratio, the more the heating position at the bottom of the cooking container can be moved inward. However, when the distribution ratio becomes larger than 0.5, the flame Fc of the child burner 10C becomes larger than the flame Fp of the main burner 10P, so even if the flame Fp of the main burner 10P is made small, the flame Fc of the child burner 10C becomes larger than the flame Fp of the main burner 10P. This is because the heating position cannot be moved inward. On the contrary, as the flame Fc of the child burner 10C becomes larger, the heating position at the bottom of the cooking container may move outward.

However, the flame Fp of the main burner 10P is formed at a position closer to the bottom of the cooking vessel than the flame Fc of the child burner 10C, so if the flame sizes are the same, the effect on the heating position of the cooking vessel will be , the flame Fp of the parent burner 10P is larger than the flame Fc of the child burner 10C. Therefore, even after the distribution ratio reaches 0.5, if the distribution ratio is a little (for example, about 0.05), the heating position at the bottom of the cooking container can be moved inward by increasing the distribution ratio. Is possible. Further, depending on the positional relationship between the parent burner 10P and the child burner 10C, there is a possibility that the distribution ratio may be further increased (for example, about 0.9). If the distribution ratio is increased, the gas flow rate to the parent burner 10P becomes smaller, so depending on the total gas flow rate, the gas flow rate to the parent burner 10P may become smaller than the lower limit gas flow rate. Therefore, when increasing the distribution ratio, the distribution ratio may be increased as long as the gas flow rate to the parent burner 10P does not become smaller than the lower limit gas flow rate.

FIG. 7 shows how the gas stove 1 of the first embodiment evenly heats the bottom of the cooking container by controlling the distribution ratio of fuel gas to the main burner 10P and child burner 10C based on the above-mentioned concept. FIG. In FIG. 7, as in the case of FIG. 4, by plotting the gas flow rate of the child burner 10C on the horizontal axis and the gas flow rate of the parent burner 10P on the vertical axis, the gas flow rate to the parent burner 10P and the child burner 10C is The state of change is expressed by the movement of coordinate points.

In addition, in FIG. 7, multiple dot-dashed straight lines are displayed downward to the right, but these straight lines represent the total gas flow rate that is the sum of the gas flow rate of the main burner 10P and the gas flow rate of the child burner 10C. It represents a straight line (hereinafter referred to as a line of equal firing power) where is constant. If the coordinate points representing the gas flow rates to the parent burner 10P and the child burner 10C are moved along the constant thermal power lines, the thermal power generated by the parent and child burners 10 as a whole does not change. In addition, in FIG. 7, there are a plurality of solid straight lines pointing upward to the right, but these straight lines are straight lines (hereinafter referred to as straight lines) in which the distribution ratio of fuel gas to the main burner 10P and the child burner 10C are constant. , equal distribution ratio line). If the coordinate point moves along the equal distribution ratio line, the distribution ratio will not change, but if the coordinate point moves across the equal distribution ratio line, the distribution ratio will change. Furthermore, among the plurality of equal distribution ratio lines, the straight line shown as a thick solid line is a straight line with a distribution ratio of a value similar to that of a conventional general gas stove (in this example, the distribution ratio is 0.15). . In the following, the distribution ratio indicated by this straight line will be referred to as the "standard distribution ratio."

Also in the gas stove 1 of the first embodiment, when switching from the independent combustion state of the child burner 10C to the simultaneous combustion state of the parent burner 10P and the child burner 10C, the coordinate points indicating the operating state of the parent and child burners 10 are as shown in FIG. This will be point c. This point c is a coordinate point where the distribution ratio between the main burner 10P and the child burner 10C is the standard distribution ratio, and the gas flow rate to the child burner 10C is the lower limit gas flow rate. This is the same coordinate point as point c in FIG. Also, in the gas stove 1 of the first embodiment, as the user increases the set thermal power, the coordinate point moves from point c toward the upper right on the thick solid equal distribution ratio line. Further, when the user decreases the set firepower, the coordinate point moves toward the lower left on the equal distribution ratio line. As a result of the user adjusting the firepower in this way, it is assumed that the coordinate point has finally moved to point e.

Then, in the gas stove 1 of the first embodiment, the coordinate point is now reciprocated along the constant thermal power line passing through point e. In the example shown in FIG. 7, the distribution ratio is gradually increased from 0.15 toward 0.5, as indicated by the thick broken line arrow in the figure, and the distribution ratio is gradually increased from 0.15 to 0.5. When the point f of No. 5 is reached, the distribution ratio is gradually decreased as shown by the thick dashed-dotted arrow in the figure. The smaller the distribution ratio, the smaller the gas flow rate of the child burner 10C. Then, when the gas flow rate of the child burner 10C decreases to the lower limit gas flow rate and the coordinate point reaches point g, the distribution ratio is increased again as indicated by the thick broken line arrow in the figure. In this way, by periodically varying the distribution ratio along the constant heating power line, it becomes possible to evenly heat the bottom of the cooking container for the reason described above using FIG. 6. In addition, when changing the distribution ratio, the distribution ratio is changed along the equal heating power line passing through point e corresponding to the heating power set by the user of the gas stove 1, so that The firepower set by the user is maintained. Therefore, it is possible to evenly heat the bottom of the cooking container using the heating power set by the user.

FIG. 8 shows how the gas stove 1 of the first embodiment adjusts the distribution ratio of fuel gas to the main burner 10P and the child burner 10C in order to evenly heat the bottom of the cooking container with the set firepower set by the user. 12 is a flowchart of distribution ratio control processing to be controlled. Note that this process is executed by the control unit 50 (see FIG. 2) installed in the gas stove 1 of the first embodiment. Further, in parallel with this process, the control unit 50 controls the gas flow rate control valve 41 according to the heating power set by the user, and ignites the fuel gas using the ignition plug 30 (see FIG. 2). Processing is also being carried out.

As shown in FIG. 8, in the distribution ratio control process, first, it is determined whether the parent-child burner 10 is in combustion operation (STEP 1). Since the control unit 50 of the gas stove 1 concurrently executes the process for causing the parent-child burner 10 to perform combustion operation, it can easily determine whether or not the parent-child burner 10 is in combustion operation. As a result, if the combustion operation is not in progress (STEP 1: no), by repeating the same judgment in STEP 1, the main burner 10 enters a standby state until the combustion operation of the parent-child burner 10 starts.

After that, when the combustion operation of the parent-child burner 10 is started, it is determined "yes" in STEP 1, and it is determined whether the set thermal power set by the user is larger than a predetermined threshold thermal power (STEP 2). Here, the threshold thermal power is the thermal power used to determine whether to operate the parent-child burner 10 in a combustion state with the child burner 10C alone or in a simultaneous combustion state with the parent burner 10P and the child burner 10C. . That is, if the set thermal power is smaller than the threshold thermal power, it is determined whether the child burner 10C is in an independent combustion state, and if the set thermal power is larger than the threshold thermal power, the main burner 10P and the child burner 10C are to be operated in a simultaneous combustion state. be done. Since the stove operation button 8 used by the user to set the set heat power is connected to the control unit 50, the control unit 50 can recognize the set heat set by the user.

As a result, if the thermal power set by the user is smaller than the threshold thermal power (STEP 2: no), the distribution ratio of fuel gas to the main burner 10P and child burner 10C is controlled to 1.0 (STEP 3). The control unit 50 fully closes the resistance adjustment valve 42p mounted on the parent side connection pipe 40p, and fully opens the resistance adjustment valve 42c installed on the child side connection pipe 40c. Control the ratio to 1.0.

After controlling the distribution ratio to 1.0 in this way (STEP 3), it is again determined whether the combustion operation is in progress (STEP 1). If the fuel operation has been stopped by the user, it is determined that the combustion operation is not in progress (STEP 1: no), and thereafter, the same determination in STEP 1 is repeated to wait until the combustion operation is started. On the other hand, if the combustion operation is in progress (STEP 1: yes), it is determined again whether the set thermal power is greater than the threshold thermal power (STEP 2). As a result, if the set thermal power is smaller than the threshold thermal power (STEP 2: no), the process returns to STEP 1 and repeats the above-described operation while controlling the distribution ratio to 1.0 (STEP 3).

On the other hand, if the set firepower is larger than the threshold firepower (STEP 2: yes), then it is determined whether a predetermined holding time has elapsed since the set firepower was set to that firepower ( STEP 4). In the first embodiment, the holding time is set to 5 seconds. Immediately after the user sets the set firepower, the retention time has not yet elapsed, so it is determined "no" in STEP 4, and in this case, the distribution ratio is changed to the standard distribution ratio (No. In one embodiment, it is controlled to 0.15) (STEP 5). The control unit 50 controls the distribution ratio to the standard distribution ratio by controlling the parent resistance adjustment valve 42p and the child resistance adjustment valve 42c to be fully open. Moreover, by doing this, the parent-child burner 10 enters a simultaneous combustion state of the parent burner 10P and the child burner 10C.

In this way, even when the distribution ratio is controlled to the standard distribution ratio (STEP 5), in the same way as when the distribution ratio is controlled to 1.0 in STEP 3, after determining whether or not combustion operation is in progress again (STEP 1), the following sequence of steps is performed. Repeat the judgment and operation. Then, while repeating these judgments and operations, if it is determined that the holding time has elapsed since the set firepower was set to a firepower greater than the threshold firepower (STEP 4: yes), this time, the secondary burner 10C The lower limit value of the distribution ratio is calculated such that the lower limit gas flow rate is the lower limit gas flow rate (STEP 6). The lower limit value of the distribution ratio is the following value.

Referring to FIG. 7, after the coordinate point moves to point e by the user of gas stove 1 increasing the set heating power, the distribution ratio changes by moving the coordinate point on the iso-heating power line passing through point e. It is increasing and decreasing. As the distribution ratio decreases, the gas flow rate of the child burner 10C also decreases, and when the distribution ratio is decreased until the coordinate point reaches point g, the gas flow rate of the child burner 10C reaches the lower limit gas flow rate. The distribution ratio at this point g becomes the lower limit value of the distribution ratio. Since the lower limit value of the distribution ratio is the distribution ratio at which the gas flow rate of the child burner 10C is the lower limit gas flow rate,
(Lower limit value of distribution ratio) = (lower limit gas flow rate of child burner 10C) / (total gas flow rate)
It can be calculated by Here, the total gas flow rate is the total gas flow rate corresponding to the isothermic power line passing through point e. Although the "lower limit gas flow rate of the secondary burner 10C" in the above formula is a fixed value, the "total gas flow rate" increases or decreases depending on the set thermal power set by the user. Therefore, in STEP 6, the lower limit value of the distribution ratio is calculated using the above formula according to the set thermal power set by the user.

After calculating the lower limit value of the distribution ratio in this way, the upper limit value of the distribution ratio is calculated (STEP 7). Here, the upper limit value of the distribution ratio is the distribution ratio at which the gas flow rate of the child burner 10C becomes the maximum gas flow rate MaxC. In FIG. 7, when considering the intersection of the isothermic power line passing through point e and the straight line of gas flow rate = MaxC of the child burner 10C, the distribution ratio at the intersection becomes the upper limit value of the distribution ratio. The upper limit value of the distribution ratio is the distribution ratio at which the gas flow rate of the child burner 10C is the maximum gas flow rate MaxC, so
(Upper limit of distribution ratio) = (Maximum gas flow rate of child burner 10C) / (Total gas flow rate)
It can be calculated by The "maximum gas flow rate of child burner 10C" in the above formula is a fixed value, but the "total gas flow rate" increases or decreases depending on the set thermal power, so in STEP 7, calculate the upper limit of the distribution ratio according to the set thermal power. .

Next, it is determined whether the calculated upper limit of the distribution ratio is greater than 0.5 (STEP 8). As described above using FIG. 6, when the distribution ratio becomes 0.5, the size of the flame Fp formed in the main burner 10P and the size of the flame Fc formed in the child burner 10C are almost the same. In the gas stove 1 of the first embodiment, the increase in the distribution ratio is limited to 0.5. Therefore, even if the calculated upper limit of the distribution ratio is greater than 0.5, it is necessary to prevent the distribution ratio from increasing beyond 0.5. Therefore, in STEP 8, it is determined whether the calculated upper limit of the distribution ratio is greater than 0.5. If the calculated upper limit value is greater than 0.5 (STEP 8: yes), the distribution ratio fluctuation range is set to a range from the previously calculated lower limit value to 0.5 (STEP 9). ). On the other hand, if the upper limit calculated in STEP 7 is smaller than 0.5 (STEP 8: no), the range from the lower limit calculated in STEP 6 to the upper limit calculated in STEP 7 is Set the range (STEP 10).

After setting the variation range of the fuel gas distribution ratio in this way, by controlling the valve opening degree of the parent side resistance control valve 42p and the valve opening degree of the child side resistance control valve 42c, the main burner 10P and the child burner 10C are controlled. The distribution ratio of fuel gas supplied to the fuel gas is periodically varied within a set range (STEP 11). Furthermore, the manner in which the distribution ratio is periodically varied may be a manner set in advance. For example, as illustrated in FIG. 9(a), the distribution ratio may be varied continuously over time, or as illustrated in FIG. 9(b), the distribution ratio may be changed in stages. It may be varied in such a manner that it changes.

After starting to vary the distribution ratio as described above, it is determined whether the set thermal power has been changed by the user of the gas stove 1 or whether the combustion operation has been stopped (STEP 12). If the set thermal power has not been changed and the combustion operation has not been stopped (STEP 12: no), by repeating the same judgment in STEP 12, it will be in a standby state until the set thermal power is changed or the combustion operation is stopped. . As a result, if either the set thermal power is changed or the combustion operation is stopped (STEP 12: yes), the variation of the distribution ratio is stopped (STEP 13).

After finishing changing the distribution ratio, the process returns to the beginning and it is determined whether the combustion operation is in progress (STEP 1). If the reason for ending the variation of the distribution ratio is that the combustion operation was stopped by the user, it is determined that the combustion operation is not in progress (STEP 1: no), and in this case, the same determination in STEP 1 is repeated. This puts it in a standby state.

On the other hand, if the reason for ending the variation of the distribution ratio is that the set thermal power has been changed by the user, it will be determined that combustion operation is in progress (STEP 1: yes), and the setting firepower has been changed by the user. It is determined whether the set thermal power is greater than the threshold thermal power (STEP 2). As a result, if the set thermal power is smaller than the threshold thermal power (STEP 2: no), the distribution ratio is changed to 1.0 (STEP 3), and independent combustion by the child burner 10C is started.
On the other hand, if the set firepower is greater than the threshold firepower (STEP 2: yes), it is determined whether a predetermined holding time has elapsed at the set firepower (STEP 4), and if the holding time has not elapsed ( STEP 4: no), the distribution ratio is controlled to the standard distribution ratio (STEP 5), and if the holding time has elapsed (STEP 4: yes), variation of the distribution ratio is started (STEP 6 to STEP 11).

In the gas stove 1 of the first embodiment, by executing the distribution ratio control process as described above, it becomes possible to evenly heat the bottom of the cooking container using the parent-child burner 10. Further, even while the distribution ratio is changing, the heating power set by the user is maintained, so that the user can heat with the heating power intended by the user, similar to a conventional general gas stove.

As described above, in the gas stove 1 of the first embodiment, even when the distribution ratio of fuel gas to the main burner 10P and the child burner 10C is periodically increased or decreased, the gas is generated in the main burner 10P and the child burner 10C. The total firepower is maintained at a constant firepower. However, the flame Fc of the child burner 10C is formed at a position farther from the bottom of the cooking container than the flame Fp of the parent burner 10P. Therefore, the thermal power of the child burner 10C tends to be less easily transmitted to the cooking container than the thermal power of the main burner 10P. In other words, even if the heat generated by the parent and child burners 10 is the same when the distribution ratio is small and large, the heat transmitted to the cooking container is different when the distribution ratio is large (the flame Fc of the child burner 10C is large). As a result, the heating efficiency of the parent-child burner 10 tends to decrease. As a result, the heating efficiency of the parent-child burner 10 is lower near the center of the cooking container, which is heated when the distribution ratio is increased, compared to the vicinity of the outer edge of the cooking container, which is heated when the distribution ratio is decreased, and the heating efficiency of the cooking container is lower. There is a possibility that the temperature may become low. Therefore, when changing the distribution ratio, the decrease in heating efficiency may be compensated for by changing the distribution ratio in such a manner as to increase the time ratio during which the distribution ratio takes a large value.

FIG. 10 is an explanatory diagram illustrating a variation mode in which the time ratio in which the distribution ratio takes a large value increases. FIG. 10(a) exemplifies a variation mode when the distribution ratio is continuously changed. With respect to the median distribution ratio indicated by the dashed line in the figure, the larger the distribution ratio, the larger the time ratio, and the smaller the distribution ratio, the smaller the time ratio. Further, FIG. 10(b) shows an example of a variation mode in which the distribution ratio is changed in stages. In this case as well, with respect to the median distribution ratio indicated by the dashed line in the figure, as the distribution ratio increases, the time ratio also increases, and as the distribution ratio decreases, the time ratio also decreases. Therefore, instead of the variation mode described above using FIG. 9, a variation mode as illustrated in FIG. 10 is stored, and when starting the variation of the distribution ratio in STEP 11 of FIG. It may be made to vary by. This makes it possible to compensate for differences in heating efficiency due to differences in distribution ratio, making it possible to heat the bottom of the cooking container more evenly.

B. Second example:
In the gas stove 1 of the first embodiment described above, after a predetermined holding time (for example, 5 seconds) has elapsed after starting heating at the set firepower set by the user, the main burner 10P and the child burner 10C are turned off. The distribution ratio of fuel gas is periodically varied. By doing so, the size of the flame Fp of the main burner 10P can be changed periodically, and the bottom of the cooking container can be heated evenly. However, if the size of the cooking container is small, when the flame Fp of the main burner 10P becomes large, the flame may overflow from the cooking container (a so-called flame overflow state). Therefore, the size of the cooking container may be detected in advance, and when changing the distribution ratio of fuel gas, the distribution ratio may be varied within a range that does not cause the flame Fp of the main burner 10P to overflow. good. The gas stove 1 of the second embodiment will be described below.

FIG. 11 is a perspective view showing the external shape of the gas stove 1 of the second embodiment. The gas stove 1 of the second embodiment illustrated in FIG. 11 is different from the gas stove 1 of the first embodiment described above using FIG. 1 in that a plurality of cooking container detection sensors 6 are mounted on the top plate 3. Although different, other points are the same as the gas stove 1 of the first embodiment. Therefore, in the second embodiment, the explanations of the same configurations as those in the first embodiment are omitted by using the same numbering as in the first embodiment.

As shown in FIG. 11, a plurality of cooking container detection sensors 6 are mounted on the top plate 3 of the gas stove 1 of the second embodiment radially from the center position of the parent-child burner 10. Although an optical sensor, an ultrasonic sensor, or the like can be used as the cooking container detection sensor 6, an ultrasonic sensor is used in the gas stove 1 of the second embodiment. In addition, in FIG. 11, three cooking container detection sensors 6 are arranged in each row of cooking container detection sensors 6 arranged radially, but a larger number of cooking container detection sensors 6 are shown. 6 may be placed. In each row, the distance from the center position of the parent-child burner 10 to each cooking container detection sensor 6 is different, but when comparing the rows, the distance from the center position of the parent-child burner 10 to the corresponding cooking container detection sensor 6 is different. are the same.

These cooking container detection sensors 6 are connected to a control section 50 (see FIG. 2). Therefore, when a cooking container is placed on the trivet 4, the control unit 50 can detect the size of the cooking container based on the outputs of the plurality of cooking container detection sensors 6. For example, if the cooking container placed on the trivet 4 is a medium-diameter cooking container, the outermost cooking container detection sensor 6 from the center position of the parent-child burner 10 will be located outside the cooking container. . Therefore, even if ultrasonic waves are emitted upward from the cooking container detection sensor 6, the ultrasonic waves will pass through the outside of the cooking container and will not be reflected back, so the cooking container detection sensor 6 cannot detect the cooking container.

On the other hand, the inner cooking container detection sensor 6 is in a state where the bottom surface of the cooking container exists above. Therefore, when ultrasonic waves are emitted upward from the cooking container detection sensor 6, the ultrasonic waves are reflected from the bottom of the cooking container and returned, so that the cooking container detection sensor 6 can detect the cooking container. From this, if the outermost cooking container detection sensor 6 from the center position of the parent-child burner 10 cannot detect the cooking container, but the inner cooking container detection sensor 6 can detect the cooking container, the It can be determined that a medium-sized cooking container is placed there.

Even when a small-diameter or large-diameter cooking container is placed on the trivet 4, the size of the cooking container can be determined in the same manner. For example, if the innermost cooking container detection sensor 6 can detect a cooking container, but the outermost cooking container detection sensor 6 cannot detect a cooking container, the cooking container on the trivet 4 is determined to be a small diameter cooking container. be able to. Further, if the outermost cooking container detection sensor 6 can also detect the cooking container, it can be determined that the cooking container on the trivet 4 is a large diameter cooking container.

In the above, the cooking container detection sensor 6 is an ultrasonic sensor, and by emitting ultrasonic waves from the cooking container detection sensor 6 and detecting the ultrasonic waves reflected by the cooking container and returned by the cooking container detection sensor 6, The explanation has been made assuming that the cooking container is detected. However, by employing an optical sensor as the cooking container detection sensor 6, emitting light upward from the cooking container detection sensor 6, and detecting the light reflected by the cooking container and returned by the cooking container detection sensor 6. , a cooking container may be detected. Alternatively, the size of the cooking container may be detected by the user of the gas stove 1 taking an image of the cooking container placed on the trivet 4, and the control unit 50 acquiring and analyzing the image. good. Note that the cooking container detection sensor 6 of the second embodiment corresponds to the "detection means" in the present invention.

Regardless of which method is used, if the size of the cooking container placed on the trivet 4 can be detected, it is possible to estimate the gas flow rate of the main burner 10P when the flame overflows. Therefore, if the distribution ratio of fuel gas is varied within the range where the gas flow rate of the main burner 10P does not exceed the gas flow rate that causes a flame overflow condition, a flame overflow condition will occur due to the variation in the distribution ratio. can be avoided.

FIG. 12 is an explanatory diagram showing how the gas stove 1 of the second embodiment controls the distribution ratio of fuel gas to the main burner 10P and the child burner 10C based on the above-mentioned concept. In FIG. 12, a broken line indicating the gas flow rate (hereinafter referred to as upper limit gas flow rate) at which the flame Fp of the main burner 10P becomes overflowing is added to FIG. 7 shown for the gas stove 1 of the first embodiment.

In FIG. 12, as in FIG. 7 described above, when the user of the gas stove 1 adjusts the set firepower, the coordinate point indicating the operating state of the parent-child burner 10 moves on the equal distribution ratio line shown by the thick solid line in the figure. do. Then, if the coordinate point is at point e when the user completes the thermal power adjustment, the distribution ratio of the fuel gas is changed so that the coordinate point moves back and forth along the constant thermal power line passing through point e. become.

When increasing the distribution ratio, the distribution ratio is gradually increased from the standard distribution ratio to a distribution ratio of 0.5, as indicated by the thick broken line arrow in the figure. When the distribution ratio reaches point f, where the distribution ratio is 0.5, the distribution ratio is gradually decreased as indicated by the thick dashed line arrow in the figure. The smaller the distribution ratio, the larger the gas flow rate of the parent burner 10P. Then, when the coordinate point reaches point h, the gas flow rate of the parent burner 10P reaches the upper limit gas flow rate at which there is a risk of flame overflow. Therefore, by increasing the distribution ratio again, the coordinate point is moved from point h toward point f. In this way, it is possible to heat the bottom of the cooking container evenly by varying the distribution ratio within a range that does not overflow with flames.

In the example shown in FIG. 12, the lower limit value of the distribution ratio is the distribution ratio at which the gas flow rate distributed to the parent burner 10P is the gas flow rate (that is, the upper limit gas flow rate) at which a flame overflow condition occurs in the parent burner 10P. The ratio is determined. However, the value of the upper limit gas flow rate increases as the cooking vessel becomes larger. Therefore, if the cooking container is sufficiently large, the lower limit value of the distribution ratio will be limited not by the upper limit gas flow rate of the master burner 10P but by the lower limit gas flow rate of the child burner 10C (as in FIG. 7 described above). Become.

13 and 14 are flowcharts of the distribution ratio control process executed by the control unit 50 installed in the gas stove 1 of the second embodiment. The distribution ratio control process of the second embodiment shown in FIGS. 13 and 14 differs from the distribution ratio control process of the first embodiment described above with reference to FIG. 8 in that the size of the cooking container is detected to determine the distribution ratio. The difference is that the lower limit of is calculated, but other aspects are the same. Therefore, the distribution ratio control process of the second embodiment will be described below, focusing on the differences from the first embodiment.

As shown in FIG. 13, in the distribution ratio control process of the second embodiment as well, it is first determined whether or not the parent-child burner 10 is in combustion operation (STEP 51). As a result, if the combustion operation is not in progress (STEP 51: no), by repeating the same determination in STEP 51, the main burner 10 enters a standby state until the combustion operation of the parent-child burner 10 starts.

When the combustion operation of the parent-child burner 10 is started, it is determined "yes" in STEP 51, and it is determined whether the set thermal power is larger than a predetermined threshold thermal power (STEP 52). As a result, if the set thermal power is smaller than the threshold thermal power (STEP 52: no), the fuel gas distribution ratio is controlled to 1.0 (STEP 53), and the process returns to the beginning to determine whether combustion operation is in progress again. Determine (STEP 51). On the other hand, if the set firepower is larger than the threshold firepower (STEP 52: yes), it is determined whether a predetermined holding time (for example, 5 seconds) has elapsed at the set firepower (STEP 54).

As a result, if the holding time has not yet elapsed (STEP 54: no), the distribution ratio is controlled to the standard distribution ratio (STEP 55). Subsequently, in the distribution ratio control process of the second embodiment, the size of the cooking container placed on the trivet 4 is detected (STEP 56). As described above using FIG. 11, the size of the cooking container can be detected using the cooking container detection sensor 6 mounted on the top plate 3.

Even when the distribution ratio is controlled to the standard distribution ratio (STEP 55), in the same way as when the distribution ratio is set to 1.0 in STEP 53, it is determined again whether or not combustion operation is in progress (STEP 51), and a series of subsequent determinations are made. and repeat the operation. While repeating these judgments and operations, if it is judged that the holding time has elapsed (STEP 54: yes), the upper limit gas flow rate of the main burner 10P corresponding to the size of the cooking container detected in STEP 56 is determined. Acquire (STEP 57). The upper limit gas flow rate of the parent burner 10P is the gas flow rate at which the parent burner 10P becomes overflowing with flames. The size of the flame Fp of the main burner 10P increases as the gas flow rate increases, so if the size of the cooking container is known, it is possible to determine the gas flow rate at which the main burner 10P becomes overflowing with flames. In STEP 57, the upper limit gas flow rate for the size of the cooking container detected in STEP 56 is acquired.

Subsequently, the lower limit value (first lower limit value) of the distribution ratio corresponding to the upper limit gas flow rate of the parent burner 10P obtained in this way is calculated (STEP 58). The first lower limit value is the distribution ratio at which the gas flow rate distributed to the parent burner 10P is the upper limit gas flow rate out of the total gas flow rate corresponding to the set thermal power.
(1st lower limit value) = (upper limit gas flow rate of parent burner 10P) / (total gas flow rate)
It can be calculated by

After calculating the first lower limit value of the distribution ratio in this way, the lower limit value (second lower limit value) of the distribution ratio corresponding to the lower limit gas flow rate of the child burner 10C is calculated (STEP 59). The second lower limit value is the distribution ratio at which the gas flow rate distributed to the slave burner 10C is the lower limit gas flow rate out of the total gas flow rate corresponding to the set thermal power.
(2nd lower limit value) = (lower limit gas flow rate of child burner 10C) / (total gas flow rate)
It can be calculated by

Subsequently, it is determined whether the first lower limit value calculated in STEP 58 is larger than the second lower limit value calculated in STEP 59 (STEP 60). That is, as described above using FIG. 12, the lower limit of the range in which the distribution ratio is varied is determined by the upper limit gas flow rate at which the flame Fp of the main burner 10P is overflowing, and when it is determined by the upper limit gas flow rate at which the flame Fp of the master burner 10P is stable. There are cases where it is determined by the lower limit gas flow rate that allows combustion to continue. Therefore, by comparing the first lower limit value calculated from the upper limit gas flow rate of the parent burner 10P and the second lower limit value calculated from the lower limit gas flow rate of the child burner 10C, which one is the lower limit value of the variation range of the distribution ratio. judge whether it will happen. As a result, if the first lower limit value is larger than the second lower limit value (STEP 60: yes), the first lower limit value is set as the lower limit value of the variation range (STEP 61). On the other hand, if the first lower limit value is smaller than the second lower limit value (STEP 60: no), the second lower limit value is set as the lower limit value of the variation range (STEP 62).

Once the lower limit value of the variation range for varying the distribution ratio is set in this way, the upper limit value of the distribution ratio at which the slave burner 10C reaches the maximum gas flow rate MaxC is calculated (STEP 63). Similar to the first embodiment described above using FIG. 7, the upper limit of the distribution ratio at which the slave burner 10C reaches the maximum gas flow rate MaxC is:
(Upper limit of distribution ratio) = (Maximum gas flow rate of child burner 10C) / (Total gas flow rate)
It can be calculated by

Subsequently, it is determined whether the calculated upper limit value of the distribution ratio is greater than 0.5 (STEP 64 in FIG. 14). As a result, if the upper limit value of the distribution ratio is larger than 0.5 (STEP 64: yes), change the range of fluctuation of the distribution ratio from the lower limit value set in STEP 61 or STEP 62 of FIG. 13 to 0.5. (STEP 65). On the other hand, if the upper limit value calculated in STEP 63 is smaller than 0.5 (STEP 64: no), from the lower limit value set in STEP 61 or STEP 62 in FIG. 13 to the upper limit value calculated in STEP 63. The range is set as the variation range of the distribution ratio (STEP 66).

After setting the variation range of the fuel gas distribution ratio in this way, the distribution ratio is periodically varied within the set range (STEP 67). As a mode of periodically changing the distribution ratio, the mode illustrated in FIG. 9 or FIG. 10 can be used. After starting to change the distribution ratio, it is determined whether the set thermal power has been changed by the user of gas stove 1 or whether the combustion operation has been stopped (STEP 68). If it has not been stopped (STEP 68: no), the same judgment in STEP 68 is repeated to enter a standby state.

As a result, if either the set thermal power is changed or the combustion operation is stopped (STEP 68: yes), after stopping the fluctuation of the distribution ratio (STEP 69), the process returns to the beginning and the combustion operation is stopped. It is determined whether or not (STEP 51 in FIG. 13). In the gas stove 1 of the second embodiment, by executing the distribution ratio control process as described above, it is possible to uniformly heat the bottom of the cooking container without causing a flame overflow condition.

C. Variant example:
There are several modifications to the first and second embodiments described above. Below, the differences between these modified examples and the first and second embodiments will be briefly explained.

C-1. First modification:
In the first and second embodiments described above, by controlling the resistance adjustment valve 42p mounted on the parent side connection pipe 40p and the resistance adjustment valve 42c mounted on the child side connection pipe 40c, The explanation has been made assuming that the distribution ratio of fuel gas to the main burner 10P and the child burner 10C is changed. However, the resistance adjustment valve 42p on the parent side and the resistance adjustment valve 42c on the child side merely change the distribution ratio of fuel gas to the parent burner 10P and the child burner 10C. Therefore, instead of mounting the resistance adjustment valve 42p on the connection pipe 40p on the parent side and mounting the resistance adjustment valve 42c on the connection pipe 40c on the child side, the gas supply pipe 40 connects the connection pipe 40p on the parent side and the child side. A distribution valve for changing the distribution ratio of fuel gas may be provided at a position where the fuel gas branches into the pipe 40c.

FIG. 15 shows a parent-child burner 10 of a first modification that includes such a distribution valve 45. The parent-child burner 10 of the first modification is different from the parent-child burners 10 of the first and second embodiments described above with reference to FIG. , a distribution valve 45 is used, but other points are the same as the first and second embodiments.

The distribution valve 45 is a well-known distribution valve with one inlet port, two outlet ports, and an internally moving valve body. In the distribution valve 45, when the built-in valve body is moved, the opening area of one outflow port increases, and the opening area of the other outflow port decreases accordingly. A gas supply pipe 40 is connected to the inflow port, a parent side connection pipe 40p is connected to one outflow port, and a child side connection pipe 40c is connected to the other outflow port. The control unit 50 can control the position of the valve body of the distribution valve 45.

In the parent-child burner 10 of the first modification, the control unit 50 controls the position of the valve body of the distribution valve 45 to control the fuel gas flowing into the distribution valve 45 from the gas supply pipe 40 at an appropriate ratio. , can be distributed to the parent side connection pipe 40p and the child side connection pipe 40c. As a result, by periodically varying the distribution ratio in the same manner as in the first and second embodiments described above, it is possible to evenly heat the bottom of the cooking container.

C-2. Second variant:
Furthermore, in the first and second embodiments described above, the gas flow rate control valve 41 mounted on the gas supply pipe 40 controls the total gas flow rate of the fuel gas, and the gas flow rate control valve 41 mounted on the parent side connecting pipe 40p The explanation has been made assuming that the resistance adjustment valve 42p and the resistance adjustment valve 42c mounted on the child side connecting pipe 40c control the distribution ratio of the fuel gas. Therefore, the gas flow rate supplied to the main burner 10P is controlled by the gas flow rate control valve 41 and the resistance control valve 42p, and the gas flow rate supplied to the slave burner 10C is controlled by the gas flow rate control valve 41 and the resistance control valve 42c. will be done.

However, if the resistance adjustment valve 42p on the parent side is provided with a function to adjust the gas flow rate to the parent burner 10P, and the resistance adjustment valve 42c on the child side is provided with a function to adjust the gas flow rate to the child burner 10C, the gas The flow rate control valve 41 can also be made unnecessary.

FIG. 16 shows such a parent-child burner 10 of a second modification. The parent-child burner 10 of the second modification is different from the parent-child burner 10 of the first and second embodiments described above using FIG. 2 in that the gas supply pipe 40 is not equipped with the gas flow rate control valve 41 It's different. In the parent-child burner 10 of this second modification, it is possible to independently increase or decrease the gas flow rate to the parent burner 10P and the gas flow rate to the child burner 10C. By appropriately controlling the valve 42c, it is possible to operate the valve 42c in the same manner as in the first embodiment or the second embodiment. Note that the resistance adjustment valve 42p and the resistance adjustment valve 42c of the second modified example described above correspond to the "distribution ratio changing means" and the "gas flow rate adjustment means" in the present invention.

C-3. Third variation:
In the first and second embodiments described above, it has been explained that once the set thermal power is set by the user, the distribution ratio is varied while maintaining the set thermal power. However, as described above, when the distribution ratio is small, the flame Fp of the main burner 10P formed at a position far from the cooking vessel is large, but the flame Fp of the child burner 10C formed at a position near the cooking vessel is large. Since the flame Fc becomes smaller, the heating efficiency tends to decrease. Conversely, when the distribution ratio is large, the flame Fp of the main burner 10P formed far from the cooking container is small, but the flame Fc of the child burner 10C formed near the cooking container is large. Therefore, heating efficiency tends to increase. For the above reasons, the temperature of the part of the bottom of the cooking container that is heated when the distribution ratio is small (the flame Fp of the main burner 10P is large) tends to be difficult to rise due to low heating efficiency. arise. On the other hand, in the area that is heated when the distribution ratio is large (the flame Fc of the child burner 10C is large), the temperature tends to rise because the heating efficiency is high, and there is a possibility that temperature distribution will occur at the bottom of the cooking container. There is.

Therefore, instead of varying the distribution ratio while maintaining the set firepower set by the user, if the distribution ratio is small, the firepower will be greater than the set firepower, and if the distribution ratio is large, the firepower will be greater than the set firepower. The distribution ratio may be varied by decreasing the amount.

FIG. 17 is an explanatory diagram showing how the gas stove 1 of the third modified example changes the distribution ratio. In FIG. 17 as well, similarly to FIG. 7 shown for the gas stove 1 of the first embodiment, the distribution ratio is varied from point e corresponding to the set thermal power set by the user. However, in FIG. 7 described above, the distribution ratio is varied between points f and g on the iso-power line passing through point e, whereas in FIG. The distribution ratio is varied between points i and j that are outside the range. As the distribution ratio increases from the distribution ratio at point e (standard distribution ratio), the coordinate points move away in the direction in which the total gas flow rate decreases, and as the distribution ratio decreases from the standard distribution ratio, the total gas flow rate increases. The coordinate points move away from each other in the direction that increases.

In this way, even if the heating efficiency of the parent-child burner 10 changes by varying the distribution ratio, if the distribution ratio increases and the heating efficiency increases, the total gas flow rate is reduced (therefore, the parent-child burner 10 The increase in heating efficiency can be compensated for by reducing the generated thermal power. Furthermore, when the distribution ratio becomes smaller and the heating efficiency decreases, the decrease in heating efficiency can be compensated for by increasing the total gas flow rate (thus increasing the thermal power generated by the parent-child burner 10). As a result, it is possible to avoid the possibility that a slight temperature distribution may occur at the bottom of the cooking container.

Although the gas stove 1 equipped with the parent-child burner 10 of various embodiments and modifications has been described above, the present invention is not limited to the embodiments and modifications described above, and various modifications may be made without departing from the gist thereof. It is possible to implement it in the following manner.

For example, in the various embodiments and various modifications described above, the parent-child burner 10 including the parent burner 10P and the child burner 10C having a smaller maximum thermal power than the parent burner 10P is described as being mounted on the gas stove 1. However, instead of the parent-child burner 10, the gas stove 1 may be a gas stove 1 equipped with a double burner in which two burners of the same size and maximum thermal power are arranged one above the other.

1... Gas stove, 2... Stove body, 3... Top plate, 4... Trivet,
5...Temperature sensor, 6...Cooking container detection sensor, 7...Grill door,
8... Stove operation button, 9... Grill operation button, 10... Parent-child burner,
10C...child burner, 10P...main burner, 11...burner body,
11a... Placement surface, 11b... Burner body, 12... Parent mixing tube,
12o...open end, 13...child mixing tube, 13o...open end, 14...center cylindrical body,
15... Cylindrical body, 15a... Fitting surface, 16... Mixing chamber, 16c... Child mixing chamber,
16p... Parent mixing chamber, 20... Burner cap, 20h... Insertion hole,
21...Upper cap portion, 21a...Downward cylindrical wall, 21b...Upper groove,
21f... Upper flame port, 22... Lower cap portion, 22a... Partition tube,
22b...lower groove, 22c...upward cylindrical wall, 22d...lower groove,
22f...lower flame outlet, 22u...child flame outlet, 30...spark plug,
31... Ignition target, 32... Flame sensor, 40... Gas supply pipe,
40c...connection pipe, 40p...connection pipe, 41...gas flow rate control valve,
42c...Resistance adjustment valve, 42p...Resistance adjustment valve, 43c...Gas injection nozzle,
43p...Gas injection nozzle, 45...Distribution valve, 50...Control unit.

Claims (8)

In a gas stove that heats the bottom of a cooking container, it is equipped with a double burner in which two annular burners are coaxially arranged.
a fuel gas supply passage that supplies fuel gas to the two burners of the double burner;
a gas flow rate adjusting means provided in the fuel gas supply passage and adjusting a total gas flow rate of the fuel gas supplied to the two burners of the double burner;
a set thermal power acquisition means for acquiring a set thermal power set by a user of the gas stove;
control means for controlling the gas flow rate adjusting means so that the total gas flow rate is a gas flow rate corresponding to the set thermal power;
Distribution ratio changing means, which is provided in the fuel gas supply passage downstream of the gas flow rate adjusting means, and changes the distribution ratio of the fuel gas between one burner and the other burner of the double burner. Equipped with and
The gas stove, wherein the control means is capable of periodically increasing/decreasing the distribution ratio of the fuel gas while the set thermal power is maintained. The gas stove according to claim 1,
The double burner is a parent-child burner in which a parent burner is mounted as the one burner, and a child burner having a smaller maximum thermal power than the parent burner is mounted as the other burner. The gas stove according to claim 1 or 2,
A predetermined lower limit gas flow rate is set for at least one of the two burners of the double burner,
The control means increases or decreases the distribution ratio within a range in which a gas flow rate of the fuel gas to the burner for which the lower limit gas flow rate is set among the two burners of the double burner does not fall below the lower limit gas flow rate. A gas stove characterized in that the distribution ratio changing means is controlled so as to. In the gas stove according to any one of claims 1 to 3,
a trivet on which the cooking container is placed;
and detection means for detecting the size of the cooking container placed on the trivet,
The control means is configured to increase or decrease the distribution ratio for any burner of the double burner within a range in which the gas flow rate of the fuel gas does not exceed an upper limit gas flow rate depending on the size of the cooking container. A gas stove characterized by controlling the distribution ratio changing means. The gas stove according to any one of claims 1 to 4,
When the set thermal power is changed, the control means maintains the distribution ratio of the fuel gas at a predetermined standard distribution ratio for a predetermined holding time, and then the set thermal power is not changed during the holding time. In this case, the distribution ratio is periodically increased or decreased. The gas stove according to any one of claims 1 to 5,
The control means adjusts the distribution ratio in such a manner that a time ratio in which the distribution ratio increases with respect to a median value of the distribution ratio that increases or decreases and a time ratio in which the distribution ratio decreases with respect to the median value are different. A gas stove characterized in that the distribution ratio changing means is controlled to increase or decrease the distribution ratio. The gas stove according to any one of claims 1 to 5,
The gas stove, wherein the control means controls the gas flow rate adjusting means so that the total gas flow rate also increases or decreases in synchronization with a cycle in which the distribution ratio increases or decreases. The gas stove according to any one of claims 1 to 7,
The two burners of the double burner are arranged one above the other. A gas stove characterized in that the two burners are arranged one above the other.

Images