JP7489860B2 - Gas stove - Google Patents

Description

The present invention relates to a gas stove equipped with a parent-child burner, in which a parent burner and a child burner with a lower maximum heat output than the parent burner are arranged on the same axis.

Parent-child burners, in which a parent burner and a child burner with a lower maximum firepower than the parent burner are arranged on the same axis, are widely used. A gas stove equipped with such parent-child burners can achieve a wide range of firepower by switching between a state in which the child burner burns alone (single combustion state) and a state in which the parent burner and child burner burn simultaneously (simultaneous combustion state). Here, switching between the single combustion state and the simultaneous combustion state is achieved as follows. First, the gas supply passage that supplies fuel gas to the parent and child burners is branched into two connecting passages along the way, one connecting passage is connected directly to the child burner, and the other connecting passage is connected to the parent burner via an opening and closing valve. In this way, when the opening and closing valve is closed, fuel gas is not supplied to the parent burner, so the child burner burns alone, but when the opening and closing valve is opened, fuel gas is also supplied to the parent burner, so the parent burner and child burner burn simultaneously. In addition, the flow rate of gas supplied to the parent burner and child burner is adjusted using a gas flow control valve provided in the gas supply passage upstream of the branching position.

A gas stove equipped with such parent and child burners can achieve a wide range of heat power from low to high, but if the cooking container to be heated is small in diameter, the flame will overflow from the bottom of the cooking container (a so-called flame overflow state). When the flame overflows, the cooking container cannot be heated efficiently, and the handle of the cooking container may become hot due to the flame, causing discomfort to the user. To avoid such problems, a technology has been proposed that detects the size of the cooking container and limits the maximum heat power of the gas stove (Patent Document 1).

JP 2001-201053 A

However, with the above-mentioned proposed technology, the maximum heat output is limited by the size of the cooking vessel, meaning that the advantage of the parent-child burner, which is the wide range of heat output, cannot be utilized.

This invention was made to solve the above-mentioned problems with the conventional technology, and aims to provide a gas stove that can prevent flame overflow without limiting the maximum heat output of the parent and child burners.

In order to solve the above problems, the first gas stove of the present invention adopts the following configuration.
A gas stove for heating a cooking vessel using a parent-child burner in which a parent burner and a child burner having a lower maximum heat output than the parent burner are arranged on the same axis,
a gas supply passage that supplies fuel gas to the parent and child burners and branches into two connection passages at a branching position, one of the connection passages being connected to the parent burner and the other of the connection passages being connected to the child burner;
a gas flow rate adjusting means provided in the gas supply passage upstream of the branching position to adjust a flow rate of the fuel gas;
a distribution ratio changing means provided at the branching position or in the two connecting passages, for changing a distribution ratio of the fuel gas between the parent burner and the child burner;
A control means for controlling the gas flow rate adjusting means and the distribution ratio changing means in response to a heat setting set by a user of the gas stove ;
A trivet on which the cooking vessel is placed;
a flame overflow state monitoring means for monitoring whether or not the flame formed by the parent burner overflows from the cooking vessel;
Equipped with
The control means is characterized in that, when the flame overflow state is detected, it is capable of controlling the distribution ratio changing means so that the distribution ratio to the child burners increases as the set fire power increases.

In the first gas stove of the present invention, the gas supply passage for supplying fuel gas branches into two connecting passages, one of which is connected to the parent burner and the other to the child burner. The flow rate of the fuel gas flowing through the gas supply passage and the distribution ratio of the fuel gas to the parent burner and the child burner are controlled according to the set fire power set by the user of the gas stove. The presence or absence of a flame overflow state in which the flame formed by the parent burner overflows the cooking container on the trivet is monitored, and if a flame overflow state is detected, the distribution ratio to the child burner can be increased as the set fire power increases.

If the distribution ratio to the child burners is increased, the child burner flame becomes larger, and the parent burner flame becomes smaller accordingly. Therefore , if a flame overflow state in which the parent burner flame overflows the cooking vessel is detected , by increasing the distribution ratio of fuel gas to the child burners, it is possible to prevent the flame overflow state by reducing the flame of the parent burner. In addition, since the parent burner flame is reduced by increasing the distribution ratio to the child burners, reducing the flame of the parent burner increases the flame of the child burner by that amount. Therefore, the overall firepower of the parent and child burners is not reduced, and the maximum firepower is not limited.

In addition, in the first gas stove of the present invention described above, when increasing the distribution ratio to the child burner, the distribution ratio to the child burner may be increased while maintaining the total gas flow rate of the fuel gas supplied to the parent burner and the child burner.

In this way, even if the flame of the parent burner is made smaller to eliminate the flame overflow condition in the parent burner, the total flame power of the parent burner and the child burners does not change, so the user of the gas stove will not feel uncomfortable.

In order to solve the above-mentioned problems, the second gas stove of the present invention adopts the following configuration.
A gas stove for heating a cooking vessel using a parent-child burner in which a parent burner and a child burner having a lower maximum heat output than the parent burner are arranged on the same axis,
a gas supply passage that supplies fuel gas to the parent and child burners and branches into two connection passages at a branching position, one of the connection passages being connected to the parent burner and the other of the connection passages being connected to the child burner;
a gas flow rate adjusting means provided in the gas supply passage upstream of the branching position to adjust a flow rate of the fuel gas;
a distribution ratio changing means provided at the branching position or in the two connecting passages, for changing a distribution ratio of the fuel gas between the parent burner and the child burner;
A control means for controlling the gas flow rate adjusting means and the distribution ratio changing means in response to a heat setting set by a user of the gas stove;
A trivet on which the cooking vessel is placed;
A detection means for detecting the size of a cooking vessel placed on the trivet;
a flame overflow power determining means for determining a flame overflow power, which is the set flame power at which the flame formed by the parent burner overflows from the cooking vessel, based on the size of the cooking vessel;
Equipped with
The control means is characterized in that, when the set fire power exceeds the flame overflow fire power, the control means is capable of controlling the distribution ratio changing means so that the gas flow rate to the parent burner is maintained at the gas flow rate at the flame overflow fire power even if the set fire power increases .

In the second gas stove of the present invention, the flame overflow power is determined based on the size of the cooking vessel. If the set flame overflow power exceeds the flame overflow power, the gas flow rate to the parent burner is maintained at the gas flow rate at the flame overflow power by increasing the distribution ratio to the child burners. In this way, it is possible to prevent the flame overflow state without monitoring whether it occurs or not.

In order to solve the above-mentioned problems, the third gas stove of the present invention adopts the following configuration.
A gas stove for heating a cooking vessel using a parent-child burner in which a parent burner and a child burner having a lower maximum heat output than the parent burner are arranged on the same axis,
a gas supply passage that supplies fuel gas to the parent and child burners and branches into two connection passages at a branching position, one of the connection passages being connected to the parent burner and the other of the connection passages being connected to the child burner;
a gas flow rate adjusting means provided in the gas supply passage upstream of the branching position to adjust a flow rate of the fuel gas;
a distribution ratio changing means provided at the branching position or in the two connecting passages, for changing a distribution ratio of the fuel gas between the parent burner and the child burner;
a control means for controlling the gas flow rate adjusting means and the distribution ratio changing means in response to a heat setting set by a user of the gas stove;
Equipped with
The control means
When the set heating power is equal to or lower than a predetermined threshold value, the distribution ratio changing means is controlled so that the distribution ratio to the parent burner increases as the set heating power increases;
When the set fire power is greater than the threshold value, the distribution ratio changing means is controlled so that the distribution ratio to the child burners increases as the set fire power increases .

In the third gas stove of the present invention, when the set fire power is smaller than a predetermined threshold, the distribution ratio to the parent burner increases as the set fire power increases, but when the set fire power is larger than the threshold, the distribution ratio to the child burners increases as the set fire power increases. In this way, it is possible to prevent a flame overflow state from occurring when the set fire power exceeds the threshold.

Furthermore, in the first to third gas stoves of the present invention described above, at least the air flow rate of the primary air supplied to the parent burner may be made adjustable, and when the distribution ratio of the fuel gas is changed, the air flow rate of the primary air may also be adjusted.

When the fuel gas distribution ratio to the child burners is increased, the child burner's flame becomes larger, interfering with the parent burner's flame, and the parent burner in particular tends to have a shortage of secondary air used to burn the fuel gas, making it impossible to burn the fuel gas efficiently. Even in such cases, if the amount of primary air is increased, the shortage of secondary air can be compensated for, making it possible to burn the fuel gas efficiently.

1 is a perspective view showing the external shape of a gas stove 1 equipped with a parent-child burner 10 of a first embodiment. FIG. FIG. 2 is a perspective view showing the general shape of the parent-child burner 10 of the first embodiment. 1 is an exploded assembly diagram showing the internal structure of the burner body 11b and burner cap 20 of the parent-child burner 10 of the first embodiment. 1 is an explanatory diagram showing how the gas stove 1 of the first embodiment controls the gas flow rate of fuel gas supplied to the parent burner 10P and the child burner 10C according to the set heat when the cooking vessel has a large diameter. FIG. 1 is an explanatory diagram showing how the gas stove 1 of the first embodiment controls the gas flow rate of fuel gas supplied to the parent burner 10P and the child burner 10C according to the set heat when the cooking vessel has a small diameter. FIG. An explanatory diagram showing another manner in which the gas stove 1 of the first embodiment controls the gas flow rate of the fuel gas supplied to the parent burner 10P and the child burner 10C according to the set fire power when the cooking vessel has a small diameter. 10 is a perspective view showing the external shape of a gas stove 1 equipped with a parent-child burner 10 of a second embodiment. FIG. An explanatory diagram showing how the gas stove 1 of the second embodiment controls the gas flow rate of fuel gas supplied to the parent burner 10P and the child burner 10C according to the set fire power when the cooking vessel has a small diameter. 13 is an explanatory diagram showing how the control unit 50 of the gas stove 1 of the second embodiment sets the opening degree of the parent opening/closing valve 42p and the child opening/closing valve 42c according to the set heat power. FIG. FIG. 2 is an explanatory diagram of a parent-child burner 10 according to a first modified example. 1 is an explanatory diagram showing interference between a flame Fp of a parent burner 10P and a flame Fc of a child burner 10C. An explanatory diagram of a variable damper 70 mounted on a parent-child burner 10 of a second modified example. FIG. 13 is an explanatory diagram of a third modified example of a parent-child burner 10 equipped with a combustion fan 80.

A. First embodiment:
Fig. 1 is a perspective view showing the external shape of a gas stove 1 equipped with a parent-child burner 10 of the first embodiment. The gas stove 1 shown in Fig. 1 is a built-in type gas stove that is fitted into the countertop of a system kitchen (not shown) and includes a box-shaped stove body 2 and a top plate 3 that is installed to cover the open top surface of the stove body 2.

Inside the stove body 2, two parent-child burners 10, which are a combination of a parent burner and a child burner described later, are arranged side by side, and the upper parts of these parent-child burners 10 protrude from insertion holes formed in the top plate 3. In addition, a trivet 4 is installed on the top plate 3 so as to surround the protruding parts of the upper parts of each parent-child burner 10. By placing a cooking container such as a pot on the trivet 4, the cooking container can be heated from below by the parent-child burner 10. Furthermore, the parent-child burner 10 has a temperature sensor 5 built in, penetrating the center. The temperature sensor 5 is biased 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 presses down on the temperature sensor 5, so that the upper end of the temperature sensor 5 abuts against the bottom surface of the cooking container, making it possible to detect the temperature of the cooking container.

A grill door 7 is provided on the front of the gas stove 1, and a grill chamber and grill burners (not shown) are mounted behind the grill door 7. Two stove operation buttons 8 corresponding to the two parent and child burners 10 are provided to the right of the grill door 7, and the user of the gas stove 1 can ignite, extinguish, or adjust the flame power of the corresponding parent and child burner 10 by operating one of the stove operation buttons 8. A grill operation button 9 is provided on the left of the grill door 7, and the user can ignite, extinguish, or adjust the flame power of the grill burner by operating the grill operation button 9.

Furthermore, a range hood 60 is installed above the gas stove 1, and the range hood 60 is equipped with a camera 61 that takes pictures of the parent and child burners 10 from above, and a flame overflow state monitoring unit 62. The camera 61 outputs images taken during cooking with the parent and child burners 10 to the flame overflow state monitoring unit 62, which analyzes the images received from the camera 61 to monitor whether the flame of the parent and child burners 10 is overflowing from the cooking vessel during cooking. When the flame overflow state monitoring unit 62 determines that the flame is overflowing from the cooking vessel, it transmits a message to that effect to the gas stove 1 via wireless communication.

The flame overflow state monitoring unit 62 in this embodiment corresponds to the "flame overflow monitoring means" of the present invention. In the first embodiment, the flame overflow state monitoring unit 62 is mounted on the range hood 60, but it may be mounted on the gas stove 1. Furthermore, the camera 61 may also be mounted on the top plate 3 of the gas stove 1. Alternatively, instead of mounting the camera 61, the flame overflow state monitoring unit 62 may obtain an image taken by an external device such as a smartphone to determine whether or not a flame is overflowing from the cooking vessel.

Figure 2 is a perspective view showing the general shape of the parent-child burner 10 of this embodiment. As shown in the figure, 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 parent mixing tube 12 connected to the burner body 11b, and a child mixing tube 13 having a smaller diameter than the parent mixing tube 12 and connected to the burner body 11b. The 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 Figure 1 is inserted into this insertion hole 20h.

The burner cap 20 is a member divided into upper and lower two sections, and is formed by casting or die casting using aluminum alloy or brass. Hereinafter, the upper member constituting the burner cap 20 will be referred to as the upper cap part 21, and the lower member will be referred to as the lower cap part 22. When the upper cap part 21 is placed on the lower cap part 22 as shown in the figure, as shown in an enlarged view in Figure 2, a plurality of upper flame ports 21f are formed on the outer peripheral surface of the upper cap part 21, and further, a plurality of lower flame ports 22f are formed on the outer peripheral surface of the lower cap part 22. The upper cap part 21 and the lower cap part 22 are combined in a position where the upper flame ports 21f and the lower flame ports 22f are staggered.

When the burner cap 20 is placed on the burner body 11b, multiple small flame ports (hereinafter, child flame ports 22u) are formed between the lower cap portion 22 and the burner body 11b. As described later, inside the burner body 11b, a space to which the parent mixing tube 12 is connected and a space to which the child mixing tube 13 is connected are formed. The child flame port 22u formed between the lower cap portion 22 and the burner body 11b is connected to the space to which the child mixing tube 13 is connected. In addition, the upper flame port 21f formed in the upper cap portion 21 and the lower flame port 22f formed in the lower cap portion 22 are connected to the space to which the parent mixing tube 12 is connected. Therefore, as 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 upper flame port 21f and the lower flame port 22f.

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

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

In addition, a gas flow rate control valve 41 for adjusting the gas flow rate of the fuel gas is attached to the middle of the gas supply pipe 40. Furthermore, an on-off valve 42p for adjusting the passage resistance of the connection pipe 40p is attached to the middle of the connection pipe 40p that supplies fuel gas to the parent mixing tube 12, and an on-off valve 42c for adjusting the passage resistance of the connection pipe 40c is attached to the middle of the connection pipe 40c that supplies fuel gas to the child mixing tube 13. Hereinafter, the on-off valve 42p attached to the connection pipe 40p is referred to as the "parent side on-off valve 42p", the on-off valve 42c attached to the connection pipe 40c is referred to as the "child side on-off valve 42c", and further, the on-off valve 42p and the on-off valve 42c may be collectively referred to simply as the on-off valve 42. In addition, various well-known valves capable of adjusting the gas flow rate continuously or in multiple stages can be used as the gas flow rate control valve 41, the parent on-off valve 42p, and the child on-off valve 42c, but in the first embodiment, a flow rate control valve driven by a stepping motor is used.

In this embodiment, the gas supply pipe 40 corresponds to the "gas supply passage" in the present invention, and the connection pipes 40p and 40c correspond to the "connection passage" in the present invention. The gas flow rate control valve 41 in this embodiment corresponds to the "gas flow rate control means" in the present invention, and the opening/closing valve 42 in this embodiment corresponds to the "distribution ratio changing means" in the present invention.

In addition, the burner body 11 is provided with an ignition plug 30 and a flame sensor 32 in close proximity to the outer circumferential surface of the burner body 11b, and the ignition plug 30 and the flame sensor 32 are connected to the control unit 50. Furthermore, an ignition target 31 is protruding from the outer circumferential surface of the burner cap 20 above the ignition plug 30. The control unit 50 fully closes the parent side opening and closing valve 42p provided on the connecting pipe 40p, and then opens the gas flow control valve 41 while discharging a spark from the ignition plug 30 toward the ignition target 31, causing fuel gas to flow out from the child flame port 22u, which is ignited and combustion begins. The flame sensor 32 is capable of detecting a flame generated in the child flame port 22u, and the control unit 50 can recognize that combustion has begun by detecting the flame in the child flame port 22u. Furthermore, when the parent on-off 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, and combustion also begins in the upper flame port 21f and the lower flame port 22f. Note that the control unit 50 of this embodiment corresponds to the "control means" of the present invention, since it controls the operation of the gas flow rate adjustment valve 41 and the on-off valve 42.

As shown in FIG. 2, the upper flame port 21f and the lower flame port 22f are set to have a larger opening area than the child flame port 22u. In addition, the parent mixing tube 12 communicating with the upper flame port 21f and the lower flame port 22f inside the burner body 11, and the child mixing tube 13 communicating with the child flame port 22u are also formed with a large diameter. Therefore, the upper flame port 21f and the lower flame port 22f can burn a larger amount of fuel gas than the child flame port 22u to generate a large firepower. Therefore, the parent-child burner 10 is used in such a way that while the required firepower is small, fuel gas is burned in the child flame port 22u, and when a large firepower is required, fuel gas is also burned in the upper flame port 21f and the lower flame port 22f. For this reason, the child flame nozzle 22u portion of the parent-child burner 10 is referred to as the "child burner 10C," and the upper flame nozzle 21f and lower flame nozzle 22f portions of the parent-child burner 10 are referred to as the "parent burner 10P."

As shown in FIG. 2, the parent-child burner 10 of this embodiment has a parent burner 10P and a child burner 10C arranged in two tiers, one above the other, on the same axis. However, the parent burner 10P and the child burner 10C do not necessarily have to be arranged in two tiers, and the parent burner 10 may have a child burner 10C with a smaller diameter than the parent burner 10P arranged inside the parent burner 10P, which has a circular ring shape. In addition, the parent-child burner 10 of this embodiment has two tiers of flame ports by arranging the upper flame port 21f and the lower flame port 22f of the parent burner 10P in a staggered manner, but this is not limited to the above, and the upper flame port 21f and the lower flame port 22f of the parent burner 10P may be arranged in a vertically aligned state to form a single tier of flame ports.

Figure 3 is an exploded view showing the internal structure of the burner body 11b and burner cap 20 of the parent-child burner 10 of the first embodiment. As shown in the figure, the burner body 11b, which is substantially cylindrical, has an upper end bent inward to form an annular mounting surface 11a on which the burner cap 20 is mounted. In addition, a cylindrical central cylinder 14 is erected inside the burner body 11b, and an annular mixing chamber 16 to which mixed gas is supplied is formed between the burner body 11b and the central cylinder 14.

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

As described above, the burner cap 20 comprises an upper cap portion 21 and a lower cap portion 22, with the lower cap portion 22 placed on the mounting surface 11a of the burner body 11b, and the upper cap portion 21 placed on the lower cap portion 22. As shown in the figure, the lower cap portion 22 is a substantially annular member, with a cylindrical partition wall tube 22a suspended downward from the inner edge portion. Furthermore, a plurality of lower grooves 22b are formed radially from the center of the lower cap portion 22 on the lower surface of the outer edge portion (the surface that abuts against the mounting surface 11a of the burner body 11b).

The outer edge of the lower cap portion 22 is provided with an upward cylindrical wall 22c that protrudes upward in a cylindrical shape, and the upper end surface of the upward cylindrical wall 22c is formed with a plurality of lower grooves 22d that are radially arranged from the center of the upward cylindrical wall 22c. The lower grooves 22d are not provided in a position that faces the multiple prongs of the trivet 4. In addition, an ignition target 31 protrudes from the outer peripheral surface of the upward cylindrical wall 22c at a position above the above-mentioned ignition plug 30.

On the other hand, the upper cap portion 21 is formed in a circular ring shape, and a cylindrical inner tube (not shown) is suspended downward from the inner edge portion. Furthermore, a cylindrical downward cylindrical wall 21a is provided downward from the outer edge portion, and a plurality of upper grooves 21b are formed radially from the center of the downward cylindrical wall 21a on the lower end surface of the downward cylindrical wall 21a. Note that the upper grooves 21b are not provided in a position facing the plurality of claws of the trivet 4, similar to the above-mentioned lower grooves 22d.

The upper cap part 21 and the lower cap part 22 are assembled in a state where the upper groove 21b of the upper cap part 21 and the lower groove 22d of the lower cap part 22 are positioned so that they do not overlap. Therefore, when the upper cap part 21 and the lower cap part 22 are assembled to form the burner cap 20, an upper flame port 21f is formed where the upper groove 21b opens to the outer peripheral surface of the downward cylindrical wall 21a, and a lower flame port 22f is formed where the lower groove 22d opens to the outer peripheral surface of the upward cylindrical wall 22c (see Figure 2). In addition, since the upper groove 21b and the lower groove 22d are positioned so that they do not overlap, the upper flame port 21f and the lower flame port 22f are formed in alternating positions.

When placing the burner cap 20 on the burner body 11b, first, the partition tube 22a hanging down from the inner edge of the lower cap part 22 is inserted inside the fitting surface 15a of the partition cylinder 15, while the inner tube (not shown) hanging down from the inner edge of the upper cap part 21 is inserted inside the central cylinder 14, and the burner cap 20 is lowered. Then, the lower groove 22b formed on the underside of the outer edge of the lower cap part 22 comes into contact with the mounting surface 11a of the burner body 11b, and the burner cap 20 is placed 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 inner peripheral surface of the upper part of the central cylinder 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 is connected to the child mixing tube 13. In addition, a parent mixing chamber 16p surrounded by the central cylinder 14, the partition cylinder 15, the partition cylinder 15, the partition cylinder 22a, and the upper cap part 21 is formed on the inside of the partition cylinder 15. This parent mixing chamber 16p is connected to 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 unit 50 shown in FIG. 2, and the on-off valve 42 and the gas flow rate control valve 41 are also connected to the control unit 50. When the user of the gas stove 1 operates the stove operation button 8 to set the heat to be used for cooking, the control unit 50 acquires the heat (set heat) set by the user. Then, the operation of the gas flow rate control valve 41 and the on-off valve 42 is controlled according to the set heat, so that the fuel gas is burned in the parent and child burners 10. For example, when the set heat is small, the parent on-off valve 42p is closed and the child on-off valve 42c is opened, so that the parent burner 10P is not used and the child burner 10C is burned in a single combustion state. When the set heat is large, the parent on-off valve 42p is also opened, so that the parent burner 10P and the child burner 10C are burned in a simultaneous combustion state. This makes it possible to achieve a wide range of heat levels, from low to high, depending on the heat level set by the user.

However, if the cooking vessel placed on the trivet 4 is small in diameter, realizing the heat power set by the user will cause the flame to overflow from the cooking vessel, making it impossible to heat the cooking vessel efficiently. Therefore, it has been proposed to limit the maximum heat power when the cooking vessel is small in diameter so that the flame does not overflow from the cooking vessel, but limiting the maximum heat power would undermine the advantage of the parent-child burner 10, which can achieve a wide range of heat powers.

In response to this, the control unit 50 of the first embodiment is capable of controlling the fuel gas distribution ratio between the parent burner 10P and the child burner 10C using the on-off valve 42p and on-off valve 42c, and by appropriately controlling the distribution ratio according to the heat power set by the user, even a small-diameter cooking vessel can be heated with high heat without overflowing the flames. In the following, a method is described in which the control unit 50 of the first embodiment controls the fuel gas distribution ratio between the parent burner 10P and the child burner 10C according to the heat power set by the user to make this possible.

Figure 4 is an explanatory diagram of how the control unit 50 of the first embodiment controls the distribution ratio of fuel gas between the parent burner 10P and the child burner 10C according to the heat set by the user when the cooking vessel placed on the trivet 4 is a large-diameter cooking vessel. The horizontal axis of Figure 4 represents the heat set by the user, and the vertical axis represents the gas flow rate of the fuel gas. It is customary to represent the gas flow rate of the fuel gas not by the weight or volume of the fuel gas passing through per unit time, but by the amount of heat generated when the passing fuel gas is burned. In response to this, in Figure 4, the gas flow rate of the fuel gas is displayed as an input (kcal/h) that represents the amount of heat generated by the fuel gas per unit time. In addition, in Figure 4, the reason why "total input" is displayed instead of simply an input is because the fuel gas is distributed to the parent burner 10P and the child burner 10C, and the total input (i.e., the input of the parent and child burners 10 as a whole) is represented. Furthermore, the shaded portion in FIG. 4 represents the gas flow rate supplied to the child burner 10C. Therefore, the remaining portion after subtracting the shaded portion from the total input is the gas flow rate supplied to the parent burner 10P.

As shown in FIG. 4, when the set firepower set by the user is within the range from the minimum value Smin to the specified threshold value S1, all the fuel gas is supplied to the child burner 10C. Therefore, the total input is the gas flow rate supplied to the child burner 10C. This situation can be realized by fully closing the parent-side on-off valve 42p mounted on the parent-side connecting pipe 40p, and controlling the child-side on-off valve 42c mounted on the child-side connecting pipe 40c to a half-open state between the fully closed state and the fully open state. In this state, the parent-child burner 10 is in a single combustion state in which the child burner 10C burns the fuel gas alone. Then, when the user increases the set firepower within the range up to the threshold value S1, the gas flow control valve 41 increases the gas flow rate of the fuel gas accordingly, and as a result, the firepower of the child burner 10C increases.

Figure 4 conceptually shows the flame Fc formed by the sub burner 10C in the single combustion state. As shown in the figure, the flow rate of the burning gas is small in the single combustion state, so a large flame Fc is not formed by the sub burner 10C, and the flame does not overflow from the cooking container (flame overflow state).

When the flame power set by the user becomes greater than a predetermined threshold value S1, the control unit 50 fully opens the parent on-off valve 42p, so that fuel gas is also supplied to the parent burner 10P. At this time, the child on-off valve 42c remains half-open, but the fuel gas that was previously supplied only to the child burner 10C is now distributed to the parent burner 10P and child burner 10C, causing a sudden drop in the gas flow rate to the child burner 10C. In addition, the distribution ratio of fuel gas between the parent burner 10P and child burner 10C at this time is a constant value determined by the ratio of the passage resistance of the entire passage that supplies fuel gas to the parent burner 10P to the passage resistance of the entire passage that supplies fuel gas to the child burner 10C.

Furthermore, as a result of fuel gas being supplied to the parent burner 10P and the child burner 10C in this manner, the parent and child burners 10 enter a simultaneous combustion state in which fuel gas is burned simultaneously in the parent burner 10P and the child burner 10C. Even in the simultaneous combustion state, if the user increases the set firepower, the gas flow control valve 41 increases the gas flow rate of the fuel gas, and accordingly, the gas flow rates to the parent burner 10P and the child burner 10C increase while maintaining the distribution ratio. As a result, the flame Fp formed on the parent burner 10P and the flame Fc formed on the child burner 10C become larger as the set firepower increases.

Figure 4 conceptually shows how the flame Fp formed on the parent burner 10P and the flame Fc formed on the child burner 10C in a simultaneous combustion state become larger as the set fire power increases. Also, a larger flame Fp is formed on the parent burner 10P than on the child burner 10C in response to the distribution of more fuel gas to the parent burner 10P than to the child burner 10C. Then, when the set fire power reaches the maximum value Smax, the flame Fp of the parent burner 10P and the flame Fc of the child burner 10C become the largest. However, if the cooking vessel above the trivet 4 has a sufficiently large diameter, the flame Fp of the parent burner 10P will not overflow from the cooking vessel even when the set fire power reaches the maximum value Smax.

The above describes a method in which the control unit 50 controls the gas flow rate of the fuel gas supplied to the parent burner 10P and the child burner 10C according to the set fire power when the cooking vessel placed on the trivet 4 is a large-diameter cooking vessel that does not become flame-overflowing even at the maximum set fire power. Although a conventional general parent-child burner is not equipped with a child-side opening and closing valve 42c, the gas flow rate to the parent burner 10P and the child burner 10C is controlled in a similar manner according to the set fire power in the general parent-child burner. That is, the control unit 50 of the first embodiment controls the gas flow rate to the parent burner 10P and the child burner 10C in the same manner as the conventional general parent-child burner, unless the cooking vessel is large-diameter and does not become flame-overflowing. However, if the cooking vessel placed on the trivet 4 is a small-diameter cooking vessel, controlling the gas flow rate to the parent burner 10P and the child burner 10C in the same manner as the conventional general parent-child burner (the manner shown in FIG. 4) will result in flame-overflowing. Therefore, in the first embodiment, when a small-diameter cooking vessel is placed on the trivet 4, the control unit 50 controls the gas flow rate to the parent burner 10P and the child burner 10C in the following manner.

Figure 5 is an explanatory diagram of how the control unit 50 of the first embodiment controls the gas flow rate of fuel gas to the parent burner 10P and the child burner 10C according to the set fire power when the cooking vessel placed on the trivet 4 is a small-diameter cooking vessel. When the set fire power set by the user is within the range from the minimum value Smin to the specified threshold value S1, all fuel gas is supplied to the child burner 10C, as in Figure 4 described above. Therefore, when the set fire power is in the range from the minimum value Smin to the specified threshold value S1, the parent and child burners 10 are in a single combustion state. Also, the opening and closing valve 42c on the child side at this time is in a half-open state.

When the set fire power becomes greater than the threshold value S1, as in FIG. 4 described above, the parent on-off valve 42p opens fully, and as a result, the parent burner 10P and the child burner 10C burn fuel gas simultaneously, resulting in a simultaneous combustion state. At this stage, the child on-off valve 42c remains half-open. Also, the distribution ratio of fuel gas between the parent burner 10P and the child burner 10C is the same as in FIG. 4.

When the user increases the set heat, the gas flow rate of the fuel gas passing through the gas flow control valve 41 increases, and the gas flow rate to the parent burner 10P and the child burner 10C increases accordingly, causing the flame Fp of the parent burner 10P and the flame Fc of the child burner 10C to grow larger. Eventually, the flame Fp of the parent burner 10P overflows from the cooking vessel, resulting in a flame overflow state.

As described above with reference to FIG. 1, in the gas stove 1 of the first embodiment, the presence or absence of flame overflow is monitored by the camera 61 mounted on the range hood 60 and the flame overflow state monitoring unit 62, and when the flame overflow state monitoring unit 62 detects a flame overflow state, it wirelessly transmits that information to the control unit 50. This allows the control unit 50 to detect that a flame overflow state has occurred. The set fire power that results in a flame overflow state differs depending on the size of the cooking vessel, but in FIG. 5, the flame overflow state occurs when the set fire power reaches S2.

When the control unit 50 of the first embodiment detects a flame overflow state, it closes the parent on-off valve 42p, which was in a fully open state, by a predetermined constant opening degree, thereby reducing the gas flow rate supplied to the parent burner 10P. Then, the gas flow rate to the child burner 10C increases by the amount of the reduction in the gas flow rate to the parent burner 10P. As a result, the flame Fp of the parent burner 10P, which had overflowed from the cooking vessel, becomes smaller. In addition, since the flame overflow state is detected while the user is gradually increasing the set flame power, the flame overflow state can be eliminated by simply reducing the flame Fp of the parent burner 10P a little. In addition, the flame Fc of the child burner 10C becomes larger, but since the flame Fc of the child burner 10C is originally small, the flame overflow state does not occur even if it becomes larger.

Figure 5 shows how the gas flow rate of the parent burner 10P decreases and the gas flow rate of the child burner 10C increases accordingly when the flame overflow state is detected at the stage when the set fire power reaches S2. Also, it conceptually shows how the flame Fp of the parent burner 10P becomes smaller and the flame Fc of the child burner 10C becomes larger by changing the gas flow rates of the parent burner 10P and child burner 10C in this way, eliminating the flame overflow state. Note that the parent burner 10P and child burner 10C are supplied with fuel gas that has passed through the gas flow control valve 41, and the parent side opening/closing valve 42p and child side opening/closing valve 42c simply change the distribution ratio of the fuel gas between the parent burner 10P and child burner 10C. Therefore, the fire power of the parent and child burners 10 does not change before and after the flame overflow state is eliminated.

If the user further increases the set firepower after eliminating the flame overflow state in this way, the gas flow rate passing through the gas flow rate control valve 41 is increased in accordance with the increase in the set firepower, thereby increasing the firepower of the parent and child burners 10 as a whole. However, if the flame Fp of the parent burner 10P becomes larger as a result of this, a flame overflow state will occur, so in order to keep the gas flow rate to the parent burner 10P constant, the parent side opening and closing valve 42p is closed little by little, and the child side opening and closing valve 42c is opened little by little, thereby increasing the gas flow rate to the child burner 10C. In this way, it is possible to increase the firepower of the parent and child burners 10 as a whole while preventing the flame Fp of the parent burner 10P from overflowing the cooking vessel.

At this time, the flame Fc of the child burner 10C becomes larger, but since the flame Fc of the child burner 10C is small to begin with, it will not overflow the cooking vessel even if it becomes a little larger. In addition, since the parent burner 10P is located above the child burner 10C (i.e., closer to the cooking vessel), if the flame Fp of the parent burner 10P becomes larger, it is likely to come into contact with the bottom of the cooking vessel and be guided radially outward, resulting in a flame overflow state. In contrast, the flame Fc of the child burner 10C is formed at a position far from the bottom of the cooking vessel, so the flame Fc is less likely to come into contact with the bottom of the cooking vessel and therefore is less likely to become a flame overflow state. Therefore, even if the flame Fc of the child burner 10C is made larger, it is possible to avoid a situation in which a flame overflow state occurs.

Figure 5 shows how, as the set firepower increases further from S2, the gas flow rate of the child burner 10C is increased while the gas flow rate of the parent burner 10P is kept constant. By doing this, the flame Fc of the child burner 10C is enlarged while the flame Fp of the parent burner 10P is kept large enough to prevent flame overflow, thereby increasing the firepower of the parent and child burners 10 as a whole.

The above description assumes that when a small-diameter cooking vessel is placed on the trivet 4, the user gradually increases the set heat. Of course, the user does not necessarily increase the set heat gradually. For example, there may be a sudden change from the single combustion state of the child burner 10C to a set heat higher than the set heat S2 that results in the flame overflow state shown in Figure 5. In such a case, the control unit 50 controls the parent opening/closing valve 42p and the child opening/closing valve 42c as follows.

Figure 6 is an explanatory diagram showing how the control unit 50 resolves the flame overflow state when the user suddenly increases the set firepower from the single combustion state of the child burner 10C, resulting in a flame overflow state. In the illustrated example, a case is shown in which the set firepower suddenly increases from the single combustion state of the child burner 10C to S3, which is larger than S2 at which the flame overflow state occurs. In the single combustion state of the child burner 10C, flame overflow does not occur. Therefore, as in the case of the large-diameter cooking vessel described above using Figure 4, the control unit 50 fully opens the parent-side opening/closing valve 42p in response to the increase in the set firepower to S3, which is larger than the predetermined threshold value S1, and further increases the gas flow rate using the gas flow rate control valve 41 to the gas flow rate corresponding to the set firepower S3. In addition, since the child-side opening/closing valve 42c remains in a half-destroyed state, the fuel gas that has passed through the gas flow rate control valve 41 is distributed in the same ratio as the fuel gas is distributed to the parent burner 10P and the child burner 10C in the simultaneous combustion state of Figure 4. Therefore, immediately after the set fire power is increased to S3, the parent and child burners 10 will burn fuel gas at point P shown in Figure 6.

As explained with reference to FIG. 4, if the cooking vessel placed on the trivet 4 has a large diameter, the flame overflow state will not occur even if the fuel gas is burned at point P, but if the cooking vessel has a small diameter, the flame overflow state will occur (see FIG. 5). Then, the control unit 50 recognizes that the flame overflow state has occurred through notification from the flame overflow state monitoring unit 62, and gradually closes the parent-side on-off valve 42p and gradually opens the child-side on-off valve 42c. As a result, the flame Fp of the parent burner 10P gradually becomes smaller, and the flame Fc of the child burner 10C gradually becomes larger. During this time, the gas flow rate passing through the gas flow rate control valve 41 does not change, so the total input (i.e., the total value of the gas flow rate to the parent burner 10P and the child burner 10C) does not change, and the fire power of the parent and child burners 10 as a whole is kept constant. By continuing this process until the flame overflow state monitoring unit 62 no longer detects the flame overflow state, the parent and child burners 10 will eventually burn the fuel gas at point Q in FIG. 6. The black arrows in FIG. 6 represent the path along which the control unit 50 moves the position where the fuel gas is burned to eliminate the flame overflow condition.

After the flame overflow state is thus eliminated, the parent on-off valve 42p and the child on-off valve 42c can be controlled so that the gas flow rate to the parent burner 10P is constant, as described above with reference to FIG. 5. Alternatively, the gas flow rate of the gas flow rate control valve 41 can be controlled according to the heat set by the user, and each time a flame overflow state occurs as a result, the flame overflow can be eliminated as described above with reference to FIG. 6.

B. Second embodiment:
In the above-mentioned first embodiment, when it is detected that the flame is overflowing from the cooking vessel, the distribution ratio of fuel gas to the child burner 10C is increased to eliminate the flame overflow state while maintaining the overall firepower of the parent and child burners 10. However, if the size of the cooking vessel is known, the set firepower at which the flame overflow state occurs can be estimated. Therefore, for a firepower greater than the set firepower estimated to cause the flame overflow state, the distribution ratio of fuel gas to the child burner 10C may be increased from the beginning. Even in this way, the flame overflow state can be prevented without reducing the overall firepower of the parent and child burners 10. Below, such a second embodiment will be described.

Figure 7 is a perspective view showing the external shape of a gas stove 1 equipped with a parent and child burner 10 of the second embodiment. The gas stove 1 of the second embodiment illustrated in Figure 7 differs from the gas stove 1 of the first embodiment described above with reference to Figure 1 in that it does not have a camera 61 or a flame overflow state monitoring unit 62, but instead has multiple cooking vessel detection sensors 6 mounted on the top plate 3, but is otherwise similar to the gas stove 1 of the first embodiment. Therefore, in the second embodiment, the same configuration as the first embodiment will not be described by sharing the same numbering as the first embodiment.

As shown in FIG. 7, the top plate 3 of the gas stove 1 of the second embodiment is equipped with multiple cooking vessel detection sensors 6 arranged radially from the center position of the parent and child burners 10. The cooking vessel detection sensors 6 may be optical sensors or ultrasonic sensors, but ultrasonic sensors are used in the second embodiment. In FIG. 7, the rows of the radially arranged cooking vessel detection sensors 6 are shown as having three cooking vessel detection sensors 6, but more cooking vessel detection sensors 6 may be arranged. In addition, the distance from the center position of the parent and child burners 10 to each cooking vessel detection sensor 6 differs in each row, but when comparing the rows, the distance from the center position of the parent and child burners 10 to the corresponding cooking vessel detection sensor 6 is the same.

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

In contrast, the cooking vessel detection sensor 6 on the inside has the bottom surface of the cooking vessel above it. Therefore, when ultrasonic waves are emitted upward from the cooking vessel detection sensor 6, the ultrasonic waves are reflected by the bottom surface of the cooking vessel and return, allowing the cooking vessel detection sensor 6 to detect the cooking vessel. For this reason, if the cooking vessel detection sensor 6 on the outermost side from the center position of the parent and child burners 10 cannot detect a cooking vessel, but the cooking vessel detection sensor 6 on the inner side can detect a cooking vessel, it can be determined that a medium-sized cooking vessel is placed on the trivet 4.

When a cooking vessel with a small or large diameter is placed on the trivet 4, the size of the cooking vessel can be determined in the same manner. For example, if the innermost cooking vessel detection sensor 6 can detect the cooking vessel, but the outermost cooking vessel detection sensor 6 cannot, the cooking vessel on the trivet 4 can be determined to be a small-diameter cooking vessel. Also, if the outermost cooking vessel detection sensor 6 can detect the cooking vessel, the cooking vessel on the trivet 4 can be determined to be a large-diameter cooking vessel. In the above, the cooking vessel detection sensor 6 is an ultrasonic sensor, and the cooking vessel is detected by emitting ultrasonic waves from the cooking vessel detection sensor 6, which are reflected by the cooking vessel and returned and detected by the cooking vessel detection sensor 6. However, a light sensor may be used as the cooking vessel detection sensor 6, and the cooking vessel may be detected by emitting light upward from the cooking vessel detection sensor 6, which is reflected by the cooking vessel and returned and detected by the cooking vessel detection sensor 6.

By using the above method, if the size of the cooking container placed on the trivet 4 is known, it is possible to determine whether or not a flame overflow state will occur, and if a flame overflow state will occur, it is possible to estimate the set fire power at which the flame overflow state will occur. Then, if the fire power is greater than the set fire power estimated to cause the flame overflow state, the distribution ratio of fuel gas to the sub-burner 10C can be increased to prevent the flame overflow state from occurring.

Figure 8 is an explanatory diagram showing how the control unit 50 of the second embodiment controls the distribution ratio of fuel gas to the parent burner 10P and the child burner 10C in accordance with the size of the cooking container placed on the trivet 4 so as to prevent a flame overflow state. The set fire power S4 shown in Figure 8 is the set fire power estimated to result in a flame overflow state. The set fire power that results in a flame overflow state can be estimated as follows.

First, when the flame overflow state is not taken into consideration, the control unit 50 distributes the fuel gas to the parent burner 10P and the child burner 10C at the distribution ratio described above with reference to FIG. 4. That is, while the set fire power is smaller than a predetermined threshold value S1, all the fuel gas is distributed to the child burner 10C, but when the set fire power becomes larger than the threshold value S1, the fuel gas is distributed at a constant ratio to the parent burner 10P and the child burner 10C. Therefore, if the set fire power is determined, the gas flow rate of the fuel gas distributed to the parent burner 10P is determined, and if the gas flow rate to the parent burner 10P is determined, the size of the flame Fp formed by the parent burner 10P is also roughly determined. From this, if the size of the cooking vessel is known, the set fire power that will cause the flame overflow state in that cooking vessel can be estimated. The set fire power S4 in FIG. 8 is the set fire power that is estimated to cause the flame overflow state determined in this way.

The set fire power S4 in the second embodiment corresponds to the "flame overflow fire power" in the present invention. The control unit 50 in the second embodiment detects the size of the cooking vessel based on the output of the cooking vessel detection sensor 6 and estimates the set fire power at which the flame overflows, and therefore corresponds to the "detection means" and "flame overflow fire power determination means" in the present invention.

As long as the set fire power set by the user is smaller than the set fire power S4, it is believed that the flame will not overflow, so the control unit 50 distributes fuel gas to the parent burner 10P and the child burner 10C in the manner described above with reference to FIG. 4. Therefore, the flame of the parent and child burners 10 becomes larger as the set fire power increases, but the flame will not overflow unless it exceeds the set fire power S4.

In contrast, when the set firepower exceeds S4, the control unit 50 controls the gas flow rate of the fuel gas supplied to the parent burner 10P so as to maintain the gas flow rate at the set firepower S4. Of course, as the set firepower increases from S4, the gas flow rate passing through the gas flow control valve 41 also increases from the state when the set firepower was set to S4, but the increased gas flow rate is supplied exclusively to the child burner 10C. To achieve this, the parent on-off valve 42p should be gradually closed and the child on-off valve 42c should be gradually opened as the set firepower increases from S4.

In addition, in the second embodiment, since it is not possible to detect a flame overflow state, it is not possible to detect the occurrence of a flame overflow state and correct the opening degree of the parent on-off valve 42p and the child on-off valve 42c. Therefore, when the control unit 50 in the second embodiment determines the set heat power S4 that will result in a flame overflow state based on the size of the cooking vessel, it pre-sets the opening degree of the parent on-off valve 42p and the child on-off valve 42c for the set heat power.

9 is an explanatory diagram of the state in which the control unit 50 of the second embodiment sets the opening degree of the parent-side on-off valve 42p and the child-side on-off valve 42c in correspondence with the set fire power. The set fire power S4 in FIG. 9 is the set fire power that results in a flame overflow state estimated based on the size of the cooking vessel. When the set fire power is between the minimum value Smin and a predetermined threshold value S1, the parent-side on-off valve 42p is set to a fully closed state, and the child-side on-off valve 42c is set to a half-open state with a predetermined opening degree. Also, when the set fire power is between S1 and S4, the parent-side on-off valve 42p is set to a fully open state, and the child-side on-off valve 42c is left in a half-open state. Then, when the set fire power is between S4 and the maximum value Smax, the opening degree of the parent-side on-off valve 42p is set to decrease at a constant gradient from the fully open state as the set fire power increases, and the opening degree of the child-side on-off valve 42c is set to increase at a constant gradient from the half-open state. The gradient at which the opening of the parent on-off valve 42p is decreased and the gradient at which the opening of the child on-off valve 42c is increased can be determined experimentally in advance. Alternatively, the opening can be changed according to an experimentally determined curve rather than a fixed gradient.

In this way, if the opening degree of the parent on-off valve 42p and the child on-off valve 42c is determined and stored for the set fire power, the fuel gas can be distributed to the parent burner 10P and the child burner 10C in the manner shown in FIG. 8. Therefore, even if the fire power is set to a value greater than the set fire power S4 that is estimated to cause a flame overflow state, the flame Fp of the parent burner 10P will not be larger than the flame Fp formed by the set fire power S4, so that a flame overflow state can be avoided. In addition, as the set fire power increases, the flame Fc of the child burner 10C becomes larger, so that the parent and child burners 10 as a whole can generate the set fire power.

In the above-mentioned second embodiment, the cooking container detection sensor 6 is used to detect the size of the cooking container. However, as in the above-mentioned first embodiment, the size of the cooking container may be detected based on an image of the cooking container taken by a camera mounted on the range hood 60 or the top plate 3 (or an image taken by a smartphone by the user of the gas stove 1).

In the second embodiment described above, when the size of the cooking vessel is detected, the set fire power S4 at which the flame overflows is estimated, and when the value of the fire power set by the user exceeds S4, the distribution ratio of the fuel gas to the child burner 10C is increased as the set fire power increases. However, if the size of the cooking vessel is known, it is possible to determine a distribution ratio at which the flame Fp of the parent burner 10P does not become a flame overflow state even when the set fire power reaches the maximum value Smax. Therefore, when the value of the fire power set by the user exceeds S1 (i.e., when the parent burner 10P and the child burner 10C are in a simultaneous combustion state), the distribution ratio of the fuel gas to the child burner 10C may be set to a distribution ratio determined based on the size of the cooking vessel (a distribution ratio at which the flame Fp of the parent burner 10P does not become a flame overflow state even at the set fire power Smax). This also prevents the flame Fp of the parent burner 10P from becoming a flame overflow state.

C. Modifications:
There are several variations of the first and second embodiments described above, which will be briefly described below.

C-1. First modified example:
In the above-mentioned first and second embodiments, the gas supply pipe 40 is branched into a parent-side connection pipe 40p and a child-side connection pipe 40c, and the parent-side connection pipe 40p is equipped with an on-off valve 42p, and the child-side connection pipe 40c is equipped with an on-off valve 42c. However, the parent-side on-off valve 42p and the child-side on-off valve 42c only change the ratio at which the fuel gas supplied from the gas supply pipe 40 is distributed to the parent burner 10P and the child burner 10C. Therefore, instead of mounting the on-off valve 42p on the parent-side connection pipe 40p and mounting the on-off valve 42c on the child-side connection pipe 40c, a distribution valve that changes the distribution ratio of the fuel gas may be provided at the position where the gas supply pipe 40 branches into the parent-side connection pipe 40p and the child-side connection pipe 40c.

Figure 10 shows a parent-child burner 10 of a first modified example that is equipped with such a distribution valve 45. The parent-child burner 10 of the first modified example differs from the parent-child burner 10 of the first and second embodiments described above with reference to Figure 2 in that the parent-side opening/closing valve 42p and the child-side opening/closing valve 42c are changed to distribution valves 45, but is otherwise similar to the first and second embodiments.

The distribution valve 45 is a well-known distribution valve that has one inlet port and two outlet ports and has a valve body that moves inside. When the built-in valve body of the distribution valve 45 is moved, the opening area of one outlet port increases and the opening area of the other outlet port decreases accordingly. A gas supply pipe 40 is connected to the inlet port, a parent side connection pipe 40p is connected to one outlet port, and a child side connection pipe 40c is connected to the other outlet port. The control unit 50 is capable of controlling the position of the valve body of the distribution valve 45.

In the parent-child burner 10 of the first modified example, the control unit 50 controls the position of the valve body of the distribution valve 45, so that the fuel gas flowing from the gas supply pipe 40 into the distribution valve 45 can be distributed in an appropriate ratio to the parent-side connecting pipe 40p and the child-side connecting pipe 40c. As a result, it is possible to prevent the parent-child burner 10 from entering a flame overflow state by a mechanism similar to that of the first and second embodiments described above.

C-2. Second modified example:
In the first and second embodiments described above, when the firepower is greater than the set firepower at which the flame overflows, the flame Fp of the parent burner 10P is kept large enough not to cause the flame overflow, and the flame Fc of the child burner 10C is enlarged, thereby increasing the firepower of the parent and child burners 10 as a whole. As a result, the flame interference between the parent burner 10P and the child burner 10C is likely to occur. In particular, as illustrated in FIG. 11, the flame Fp of the parent burner 10P is surrounded by the flame Fc of the child burner 10C, so that the secondary air for burning the fuel gas is likely to be insufficient, and the fuel gas cannot be burned efficiently. Therefore, a variable damper 70 for adjusting the air flow rate of the primary air may be mounted on the opening end 12o of the parent mixing tube 12 (and the opening end 13o of the child mixing tube 13).

Figure 12 is an explanatory diagram of the variable damper 70 mounted on the parent mixing tube 12 of the parent-child burner 10 of the second modified example. As shown in the figure, the variable damper 70 includes a fixed damper 71 with a short cylindrical shape and a bottom that is attached to the open end 12o (see Figure 2) of the parent mixing tube 12, a rotating damper 72 that is formed slightly larger than the fixed damper 71 and is attached in a state covering the fixed damper 71, and an actuator 73 that rotates the rotating damper 72.

The circular bottom 71a of the fixed damper 71 has a through hole 71c through which the gas injection nozzle 43p (see FIG. 2) is inserted, and on both sides of the through hole 71c, there are air intakes 71b for taking in primary air into the parent mixing tube 12. The circular bottom 72a of the rotary damper 72 has a through hole 72c through which the gas injection nozzle 43p is inserted, and on both sides of the through hole 72c, there are air intakes 72b for taking in primary air into the parent mixing tube 12. The air intake 71b of the fixed damper 71 and the air intake 72b of the rotary damper 72 are formed at positions where they at least partially overlap, so that the primary air flows into the parent mixing tube 12 from the overlapping portion of the air intake 71b and the air intake 72b. In the following, the overlapping portion of the air intake 71b and the air intake 72b may be referred to as the "primary air intake."

The fixed damper 71 is fixed to the parent mixing tube 12, but the rotary damper 72 is attached so as to be rotatable while sliding relative to the fixed damper 71. Furthermore, a gear (not shown) is formed on the outer peripheral side of the rotary damper 72, and a drive gear 73g of the actuator 73 is fitted to this gear. The actuator 73 is connected to the control unit 50, and the control unit 50 drives the actuator 73 to change the rotational position of the rotary damper 72 relative to the fixed damper 71, thereby making it possible to change the area of the portion where the air intake 71b of the fixed damper 71 and the air intake 72b of the rotary damper 72 overlap (the primary air intake). Then, by changing the area of the primary air intake, it becomes possible to change the flow rate of the primary air. In the second modified example, a step motor is used as the actuator 73, but various well-known servo motors can be used as long as the rotational position can be controlled by the control unit 50. In addition, in the second modified example, the variable damper 70 is installed only on the parent mixing tube 12, but the variable damper 70 may also be installed on the open end 13o of the child mixing tube 13 (see FIG. 2).

In the first and second embodiments described above, if the flame of the child burner 10C is enlarged to avoid flame overflow, the secondary air for burning the fuel gas in the parent burner 10P becomes insufficient (see FIG. 11), making it difficult to burn the fuel gas efficiently. In contrast, in the parent-child burner 10 of the second modified example described above, a variable damper 70 is mounted on the open end 12o (see FIG. 2) of the parent mixing tube 12, so that the flow rate of the primary air is increased by rotating the rotary damper 72 to increase the area of the primary air intake (the portion where the air intake 71b and the air intake 72b overlap), thereby compensating for the shortage of secondary air and enabling the fuel gas to be burned efficiently.

In addition, when the flame Fc of the child burner 10C is enlarged, interference with the flame Fp of the parent burner 10P causes a shortage of secondary air in the child burner 10C as well. Therefore, if the child mixing tube 13 is also equipped with the variable damper 70 described above, the shortage of secondary air can be compensated for by increasing the primary air, making it possible to burn the fuel gas efficiently. The variable damper 70 of the second modified example corresponds to the "primary air flow rate adjustment means" in this invention.

C-3. Third Modification:
In the above-mentioned second modified example, the variable damper 70 is mounted on the parent mixing tube 12 (and the child mixing tube 13) to compensate for the shortage of secondary air. However, as shown in Fig. 13, the combustion fan 80 and the open end 12o of the parent mixing tube 12 may be connected by a blower duct 81 to supply primary air from the combustion fan 80. In this way, the flow rate of the primary air can be controlled by controlling the rotation speed of the combustion fan 80 with the control unit 50. Therefore, even if the secondary air tends to be insufficient, the flow rate of the primary air can be increased to compensate for the shortage of secondary air, thereby making it possible to efficiently combust the fuel gas in the parent burner 10P.

In FIG. 13, the blower duct 81 is connected only to the parent mixing tube 12 to supply primary air from the combustion fan 80, but the blower duct 81 may also be connected to the child mixing tube 13, or a separate combustion fan 80 may be provided to supply primary air to the child mixing tube 13 as well. In this way, even if the child burner 10C is running low on secondary air, the secondary air can be supplemented by increasing the amount of primary air, making it possible to efficiently burn fuel gas in the child burner 10C as well.

The above describes the gas stove 1 equipped with parent and child burners 10 in various embodiments and various modified examples, but the present invention is not limited to the above embodiments and modified examples, and can be implemented in various forms without departing from the gist of the invention.

1...Gas stove, 2...Stove body, 3...Tabletop, 4...Trivet,
5... temperature sensor, 6... cooking container detection sensor, 7... grill door,
8... stove operation button; 9... grill operation button; 10... parent and child burners;
10C...child burner, 10P...parent burner, 11...burner body,
11a... mounting surface, 11b... burner body, 12... parent mixing tube,
12o...open end, 13...sub-mixer tube, 13o...open end, 14...central cylinder,
15: Partition cylinder; 15a: Fitting surface; 16: Mixing chamber; 16c: Sub-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 cylinder,
22b...lower groove, 22c...upward cylindrical wall, 22d...lower groove,
22f...lower flame port, 22u...sub-flame port, 30...ignition plug,
31: ignition target; 32: flame sensor; 40: gas supply pipe;
40c, 40p...connecting pipes, 41...gas flow control valve, 30...ignition plug,
42, 42c, 42p...on-off valve; 43c, 43p...gas injection nozzle;
45...distribution valve, 50...control unit, 60...range hood, 61...camera,
62: Flame overflow state monitoring unit; 70: Variable damper; 71: Fixed damper;
71a... bottom portion, 71b... air intake port, 71c... insertion hole,
72...rotary damper; 72a...bottom; 72b...air intake;
72c...insertion hole, 73...actuator, 73g...driving gear,
80...combustion fan, 81...air duct.

Claims (5)

A gas stove for heating a cooking vessel using a parent-child burner in which a parent burner and a child burner having a lower maximum heat output than the parent burner are arranged on the same axis,
a gas supply passage that supplies fuel gas to the parent and child burners and branches into two connection passages at a branching position, one of the connection passages being connected to the parent burner and the other of the connection passages being connected to the child burner;
a gas flow rate adjusting means provided in the gas supply passage upstream of the branching position to adjust a flow rate of the fuel gas;
a distribution ratio changing means provided at the branching position or in the two connecting passages, for changing a distribution ratio of the fuel gas between the parent burner and the child burner;
A control means for controlling the gas flow rate adjusting means and the distribution ratio changing means in response to a heat setting set by a user of the gas stove ;
A trivet on which the cooking vessel is placed;
a flame overflow state monitoring means for monitoring whether or not the flame formed by the parent burner overflows from the cooking vessel;
Equipped with
The gas stove is characterized in that the control means is capable of controlling the distribution ratio change means so that the distribution ratio to the child burners increases as the set fire power increases when the flame overflow state is detected . The gas stove according to claim 1,
A gas stove characterized in that, when increasing the distribution ratio to the child burner, the control means increases the distribution ratio to the child burner while maintaining the total gas flow rate of the fuel gas supplied to the parent burner and the child burner . A gas stove for heating a cooking vessel using a parent-child burner in which a parent burner and a child burner having a lower maximum heat output than the parent burner are arranged on the same axis,
a gas supply passage that supplies fuel gas to the parent and child burners and branches into two connection passages at a branching position, one of the connection passages being connected to the parent burner and the other of the connection passages being connected to the child burner;
a gas flow rate adjusting means provided in the gas supply passage upstream of the branching position to adjust a flow rate of the fuel gas;
a distribution ratio changing means provided at the branching position or in the two connecting passages, for changing a distribution ratio of the fuel gas between the parent burner and the child burner;
A control means for controlling the gas flow rate adjusting means and the distribution ratio changing means in response to a heat setting set by a user of the gas stove;
A trivet on which the cooking vessel is placed;
A detection means for detecting the size of a cooking vessel placed on the trivet;
a flame overflow power determining means for determining a flame overflow power, which is the set flame power at which the flame formed by the parent burner overflows from the cooking vessel, based on the size of the cooking vessel;
Equipped with
This gas stove is characterized in that the control means is capable of controlling the distribution ratio change means so that the gas flow rate to the parent burner is maintained at the gas flow rate at the flame overflow power even if the set fire power increases when the set fire power exceeds the flame overflow power . A gas stove for heating a cooking vessel using a parent-child burner in which a parent burner and a child burner having a lower maximum heat output than the parent burner are arranged on the same axis,
a gas supply passage that supplies fuel gas to the parent and child burners and branches into two connection passages at a branching position, one of the connection passages being connected to the parent burner and the other of the connection passages being connected to the child burner;
a gas flow rate adjusting means provided in the gas supply passage upstream of the branching position to adjust a flow rate of the fuel gas;
a distribution ratio changing means provided at the branching position or in the two connecting passages, for changing a distribution ratio of the fuel gas between the parent burner and the child burner;
a control means for controlling the gas flow rate adjusting means and the distribution ratio changing means in response to a heat setting set by a user of the gas stove;
Equipped with
The control means
When the set heating power is equal to or lower than a predetermined threshold value, the distribution ratio changing means is controlled so that the distribution ratio to the parent burner increases as the set heating power increases;
A gas stove characterized in that, when the set fire power is greater than the threshold value, the distribution ratio changing means is controlled so that the distribution ratio to the child burners increases as the set fire power increases . The gas stove according to any one of claims 1 to 4,
a primary air flow rate adjusting means for adjusting the air flow rate of primary air supplied to at least the parent burner;
The gas stove according to claim 1, wherein the control means adjusts the flow rate of the primary air using the primary air flow rate adjustment means when changing the distribution ratio of the fuel gas.

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