Gas stove

Abstract

The present application provides a gas stove which can quickly and reliably detect backfire generated by either of a main burner and a sub burner using one thermosensitive element. The stove has a cover which houses an opening of a main burner mixing pipe having the main burner and a sub burner mixing pipe of the stove burner on the inside, and a thermosensitive element is provided at a portion in the cover near the opening of the sub burner mixing pipe. The cover is provided with an upper surface plate which integrally covers the upper side of the opening of the main burner mixing pipe and the upper side of the opening of the sub burner mixing pipe, a blocking wall which is vertically arranged at an acute angle with respect to the extending arrangement direction of the main burner mixing pipe and faces the opening of the main burner mixing pipe on the side away from the sub burner mixing pipe, and a guide wall which extends from the side edge of the blocking wall towards the direction where the thermosensitive element is located and is vertically arranged at an acute angle with respect to the extending arrangement direction of the main burner mixing pipe and faces the opening of the main burner mixing pipe.

Description

Technical Field

[0001] This invention relates to a gas stove that uses a stove burner having a main burner and a secondary burner to burn a mixture of fuel gas and air to heat cooking containers. Background Technology

[0002] Gas stoves, which use burners to burn a mixture of fuel gas and air to heat cooking containers such as pots, are becoming increasingly popular. A burner consists of a burner body with multiple flame nozzles and a mixing tube connected at one end to the burner body and having an opening at the other end. When fuel gas supplied from the gas passage is injected from a nozzle into the opening of the mixing tube, the fuel gas draws in surrounding air as it flows into the mixing tube. Then, when the fuel gas and air mixture formed in the mixing tube is ejected from the flame nozzles and ignited by a spark plug, the mixture begins to burn, heating the cooking container.

[0003] In such gas stoves, if more than 95% of the flame nozzles are blocked by spilled broth when cooking, a phenomenon sometimes occurs where the flame sprays out from the opening of the mixing tube (hereinafter referred to as backflow). If backflow occurs, the gas stove will burn out. Therefore, a solution has been proposed to detect backflow by pre-installing a thermistor near the opening of the mixing tube (for example, Patent Document 1). When backflow occurs, the thermistor is heated by the flame sprayed from the opening of the mixing tube. Therefore, if the thermistor detects an abnormal temperature rise, it cuts off the gas passage and stops the supply of fuel gas.

[0004] Furthermore, in stove burners, there are known types that have a main burner and an auxiliary burner with a smaller flame than the main burner. This type of stove burner has a main burner mixing tube connected to the main burner and an auxiliary burner mixing tube connected to the auxiliary burner. Additionally, the gas passage branches into two, and fuel gas is injected from nozzles at the top of each branched gas passage into the openings of both the main burner mixing tube and the auxiliary burner mixing tube. In this case, more fuel gas is supplied to the main burner than to the auxiliary burner.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2003-28428 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In a gas stove that uses a burner with a main burner and an auxiliary burner to burn a gas mixture, either the main burner or the auxiliary burner may backflow. Therefore, in the technology of Patent Document 1, there is a problem that two thermistors are required. The reason for this is that if only one thermistor is used, there is a possibility that backflow from one burner cannot be detected, or that there is a detection delay.

[0010] The present invention was made to address the aforementioned problems in the prior art, and its object is to provide a gas stove that, although using a single thermal element, can quickly and reliably detect backflow generated in either the main burner or the auxiliary burner.

[0011] Solution for solving the problem

[0012] To address the aforementioned issues, the gas stove of the present invention employs the following structure. That is,

[0013] A gas stove burner equipped with a main burner and an auxiliary burner with a smaller flame than the main burner, wherein fuel gas is injected from nozzles at the top of each branch of the gas passage into the opening at the end of the main burner mixing pipe extending from the main burner and into the opening at the end of the auxiliary burner mixing pipe extending in a direction different from the main burner mixing pipe. The mixture of fuel gas and air passes through the main burner mixing pipe and exits from multiple flame ports of the main burner. Furthermore, the mixture passes through the auxiliary burner mixing pipe and exits from multiple flame ports of the auxiliary burner, causing combustion to heat the cooking container. This gas stove is characterized by...

[0014] The gas stove has the following features:

[0015] A cover, which houses the openings of the main burner mixing tube and the auxiliary burner mixing tube on its inner side; and

[0016] A thermal element, located within the enclosure near the opening of the auxiliary burner mixing tube.

[0017] The cover has:

[0018] The upper surface plate integrally covers the area above the opening of the main burner mixing tube and the area above the opening of the auxiliary burner mixing tube;

[0019] A sealing wall, which is erected at an acute angle relative to the extending direction of the main burner mixing tube on the side away from the auxiliary burner mixing tube, and faces the opening of the main burner mixing tube; and

[0020] The guide wall is arranged from the side edge of the sealing wall toward the direction of the heat-sensitive element facing the opening of the main burner mixing tube, and is erected at an acute angle relative to the extension direction of the main burner mixing tube.

[0021] In cases of backflow occurring in the auxiliary burner with a smaller flame, although the flame ejected from the opening of the auxiliary burner mixing tube is small, the backflow flame easily reaches the heat-sensitive element because the heat-sensitive element is located near the opening of the auxiliary burner mixing tube. The heat-sensitive element is heated, allowing for rapid and reliable detection of backflow on the auxiliary burner side. On the other hand, the opening of the main burner mixing tube is far from the heat-sensitive element and faces a triangular-shaped stagnation space surrounded by the upper surface plate of the shroud, the sealing wall, and the guide wall. When backflow occurs in the main burner, in addition to unburned gas produced by incomplete combustion, fuel gas injected from the nozzles of the branch lines on the main burner side also leaks from the opening of the main burner mixing tube in the extending direction. Therefore, by arranging the sealing wall at an acute angle relative to the extending direction of the main burner mixing tube, compared to arranging it at an obtuse angle, the diffusion of unburned gas and fuel gas along the sealing wall can be suppressed. Similarly, by arranging the guide wall at an acute angle relative to the extension direction of the main burner mixing tube, compared to an obtuse angle arrangement, the diffusion of unburned gas and fuel gas along the guide wall can be suppressed. Therefore, unburned gas and fuel gas tend to accumulate in the stagnation space, where they momentarily ignite. Consequently, the flame diffuses from the stagnation space along the guide wall towards the auxiliary burner mixing tube side. In this way, the backflow flame from the main burner is guided by the guide wall of the cover to the thermistor element, which is then heated, enabling rapid and reliable detection of backflow on the main burner side. Thus, in the gas stove of the present invention, using a single thermistor element located within the cover, rapid and reliable detection can be achieved regardless of whether backflow occurs in the main burner or the auxiliary burner.

[0022] In the gas stove of the present invention described above, the angle between the sealing wall and the guide wall can also be set to an acute angle.

[0023] In this way, if the angle between the sealing wall and the guide wall is set to an acute angle in advance, unburned gas and fuel gas become easier to accumulate in the stagnation space compared to the case where it is set to an obtuse angle in advance. This ensures the momentum of the flame spreading from the stagnation space to the mixing tube side of the auxiliary burner, thereby improving the accuracy of reaching the heat-sensitive element.

[0024] In the gas stove of the present invention described above, an auxiliary wall may be provided on the cover, which is opposite to the guide wall, and a heat-sensitive element is located between the auxiliary wall and the guide wall, so that the gap between the guide wall and the auxiliary wall narrows as it moves closer to the heat-sensitive element from the mixing tube side of the main burner.

[0025] In this way, for the back-injected flame of the main burner, it travels from the stagnation space through the space between the guide wall and the auxiliary wall toward the heat-sensitive element. As the gap between the guide wall and the auxiliary wall narrows, the flame is concentrated and its momentum increases. Therefore, the accuracy of reaching the heat-sensitive element can be improved, and the speed of reaching the heat-sensitive element can be accelerated.

[0026] Alternatively, in such a gas stove of the present invention, a blocking wall may be provided on the cover, which is arranged opposite to the guide wall from the side edge of the blocking wall on the side opposite to the guide wall.

[0027] In the reverse injection on the main burner side, if the unburned gas and fuel gas accumulated in the stagnation space are combusted momentarily, the flame will spread from the stagnation space along the sealing wall in the opposite direction to the guide wall, but the flame spread can be blocked by the blocking wall.

[0028] Alternatively, in the gas stove of the present invention described above, an electromagnetic safety valve may be included, which opens and closes the portion of the gas passage upstream of the branch portion, and uses a bimetallic thermal switch whose contacts change from a closed state to an open state as a predetermined temperature rise as a thermal element, and connects the bimetallic thermal switch in series to a power supply circuit that supplies power from a self-powered source to maintain the open state of the electromagnetic safety valve.

[0029] In this way, the bimetallic thermal switch is heated by the backflow flame, causing its contacts to open. This allows for direct disconnection of the power supply to the solenoid safety valve, enabling it to close quickly. Furthermore, since there is no need for an electrical unit to detect backflow, the product cost of the gas stove can be reduced.

[0030] In the gas stove of the present invention described above, a thermocouple may also be installed facing the flame opening, and the thermoelectric potential generated by the thermocouple may be used as the power source for the electromagnetic safety valve.

[0031] As is well known, thermocouples generate thermoelectric potential when heated. Therefore, the ignition of a stove burner can be detected based on the thermoelectric potential generated by the thermocouple facing the flame. Furthermore, if the thermoelectric potential generated by this thermocouple is used as a power source to maintain the open state of the electromagnetic safety valve, no additional power source is required. Therefore, the gas stove can be used without any restrictions on power supply. Attached Figure Description

[0032] Figure 1 This is a perspective view showing the appearance of the gas stove 1 in this embodiment.

[0033] Figure 2 This is a perspective view showing the stove burner 10 assembled in the gas stove 1.

[0034] Figure 3 This is a perspective view showing the structure for detecting backflow in the gas stove 1 of this embodiment.

[0035] Figure 4 This is a top view showing the positional relationship between the main burner mixing tube 13, the auxiliary burner mixing tube 14, and the shroud 30 of this embodiment, as viewed from above.

[0036] Figure 5 This is an explanatory diagram illustrating the detection of backflow using a bimetallic thermal switch 32 in the event that backflow occurs in either the main burner 11 or the auxiliary burner 12.

[0037] Figure 6 This is an explanatory diagram showing the circuit structure of the gas stove 1 in this embodiment, including the bimetallic thermal switch 32.

[0038] Explanation of reference numerals in the attached figures

[0039] 1. Gas stove; 2. Stove body; 3. Top plate; 5. Soup tray; 6. Burner support; 7. Control button; 8. Control lever; 10. Stove burner; 11. Main burner; 11a. Main burner flame nozzle; 12. Auxiliary burner; 12a. Auxiliary burner flame nozzle; 13. Main burner mixing pipe; 13a. Opening; 14. Auxiliary burner mixing pipe; 14a. First opening; 14b. Second opening; 20. Gas piping; 20a. Main burner branch pipe; 20b. Auxiliary burner branch pipe; 21. Electromagnetic safety valve; 22. Flow regulating valve; 23. Switching valve; 30. Cover; 30a. Upper surface plate; 30b. Left side wall (blocking wall); 30c. Right side wall; 30d. Front surface wall (guide wall); 30e. Rear surface wall (auxiliary wall); 30f. Back side wall (blocking wall); 30g. Connecting wall; 32. Bimetallic thermal switch; 40. Inlet chamber; 41. Outlet chamber; 42. Valve orifice; 43. Valve seat; 44. Valve body; 45. Solenoid; 46. First force-applying spring; 47. Rod; 48. Second force-applying spring; 50. Thermocouple; S. Retention space. Detailed Implementation

[0040] Figure 1 This is a perspective view showing the appearance of the gas stove 1 in this embodiment. The gas stove 1 in this embodiment is a single-burner stove with a single burner 10 for burning fuel gas. It has a box-shaped stove body 2 with an opening on the upper surface and a top plate 3 that covers the upper surface of the stove body 2. The upper part of the burner 10 protrudes approximately from the center of the top plate 3.

[0041] An annular soup tray 5 is installed at the opening formed in the top plate 3, and the upper part of the stove burner 10 passes through a through hole on the inner side of the soup tray 5. A fire support 6 for placing cooking containers such as pots is provided on the top plate 3, and this fire support 6 surrounds the soup tray 5. The cooking containers above are heated by combustion in the stove burner 10. In the event of spillage from the cooking containers, the spilled soup can be collected in the soup tray 5.

[0042] The front surface of the gas stove 1 is equipped with an operation button 7 that can be pressed by the user and an operation lever 8 that can be slid left and right. The user can ignite the stove burner 10 by pressing the operation button 7 and extinguish the flame by pressing it again. In addition, the user can reduce the flame by moving the operation lever 8 to the left and increase the flame by moving the operation lever 8 to the right.

[0043] Figure 2 This is a perspective view showing the stove burner 10 assembled in the gas stove 1. As shown, the stove burner 10 of this embodiment has a dual structure of a main burner and an auxiliary burner, consisting of a main burner 11 in the shape of a ring and a circular auxiliary burner 12 disposed above the inner side of the main burner 11. A main burner mixing chamber (not shown) in the shape of a ring is formed inside the main burner 11, and a plurality of main burner flame ports 11a communicating with the main burner mixing chamber open on the outer peripheral surface of the main burner 11. Similarly, a circular auxiliary burner mixing chamber (not shown) is formed inside the auxiliary burner 12, and a plurality of auxiliary burner flame ports 12a communicating with the auxiliary burner mixing chamber open on the outer peripheral surface of the auxiliary burner 12.

[0044] The main burner mixing tube 13, which communicates with the main burner mixing chamber, extends from the main burner 11 in a generally horizontal direction. In this embodiment, the main burner mixing tube 13 is integrally formed between the two metal plates, formed by stamping stainless steel sheets, and hermetically joined together. Furthermore, an opening 13a with an enlarged passage diameter is provided at the end of the main burner mixing tube 13.

[0045] An auxiliary burner mixing pipe 14 extends from the auxiliary burner 12 and communicates with the auxiliary burner mixing chamber. In this embodiment, the auxiliary burner mixing pipe 14 is formed by bending a pipe member at approximately a right angle, with its vertical portion penetrating the inner side of the main burner 11. Furthermore, at the end of the horizontal portion of the auxiliary burner mixing pipe 14, a first opening 14a is formed while maintaining a constant passage diameter, and on the circumferential surface (… Figure 2 A rectangular second opening 14b is provided through the lower surface of the main burner mixing pipe 13. In addition, the end of the auxiliary burner mixing pipe 14 may also be provided with an opening with an enlarged passage diameter, similar to the main burner mixing pipe 13.

[0046] In the gas stove 1 of this embodiment, in order to suppress the height (thickness) of the stove body 2, the horizontal portions of the main burner mixing pipe 13 and the auxiliary burner mixing pipe 14 cannot be arranged to overlap vertically. Therefore, the auxiliary burner mixing pipe 14 extends in a direction different from that of the main burner mixing pipe 13, offset horizontally. Figure 2 In this example, the auxiliary burner mixing tube 14 extends to the right relative to the main burner mixing tube 13, and as a result, the ends (openings 13a) of the main burner mixing tube 13 and the ends (first openings 14a and second openings 14b) of the auxiliary burner mixing tube 14 are separated to the left and right.

[0047] The gas piping 20 that guides fuel gas to the stove burner 10 is equipped with an electromagnetic safety valve 21 for opening and closing the gas piping 20 and a flow regulating valve 22 for regulating the flow rate of the fuel gas. As described later, the electromagnetic safety valve 21 can be opened by pressing the operating button 7. In addition, the flow regulating valve 22 can be adjusted in conjunction with the sliding operation of the operating lever 8. Furthermore, the gas piping 20 branches into a main burner branch pipe 20a and an auxiliary burner branch pipe 20b downstream of the flow regulating valve 22. In this embodiment, the main burner branch pipe 20a is equipped with a switching valve 23. By closing the switching valve 23, the main burner 11 can be extinguished, and only the auxiliary burner 12 can burn. In addition, the gas piping 20 of this embodiment corresponds to the "gas passage" of the present invention, and the main burner branch pipe 20a and the auxiliary burner branch pipe 20b of this embodiment correspond to the "branch path" of the present invention.

[0048] In the illustrated example, the gas pipe 20 branches near the end of the auxiliary burner mixing pipe 14, and the main burner branch pipe 20a is routed toward the main burner mixing pipe 13. Fuel gas is injected from a nozzle (not shown) at the top toward the opening 13a of the main burner mixing pipe 13. The injected fuel gas, through the injection effect, draws in surrounding air and flows into the main burner mixing pipe 13. The mixture of fuel gas and air passing through the main burner mixing pipe 13 is supplied to the main burner mixing chamber and ejected from the main burner flame port 11a. Then, when ignited using a spark plug (not shown), combustion of the mixture begins, forming a flame outside the main burner flame port 11a.

[0049] Furthermore, when fuel gas is injected from a nozzle (not shown) at the top of the auxiliary burner branch pipe 20b (branched from the gas pipe 20) toward the first opening 14a of the auxiliary burner mixing pipe 14, air is entrained from the second opening 14b. The mixture of fuel gas and air passing through the auxiliary burner mixing pipe 14 is supplied to the auxiliary burner mixing chamber and ejected from the auxiliary burner flame port 12a. Then, combustion of the mixture is initiated by ignition, and a flame is formed outside the auxiliary burner flame port 12a. In addition, in the stove burner 10 of this embodiment, the amount of fuel gas supplied to the auxiliary burner mixing pipe 14 is set to be less than the amount of fuel gas supplied to the main burner mixing pipe 13, corresponding to the smaller flame intensity of the auxiliary burner 12 compared to the main burner 11.

[0050] In this gas stove 1, when cooking liquid spills from the cooking container on the burner 6, it may splash onto the main burner 11 and the auxiliary burner 12. Furthermore, when the spilled liquid blocks approximately 95% or more of the flame openings 11a and 12a of the main burner and auxiliary burner, the fuel gas ejected from the nozzle flows backward and leaks from the opening 13a of the main burner mixing pipe 13 or the first opening 14a or the second opening 14b of the auxiliary burner mixing pipe 14, resulting in flame ejection from the openings 13a, 14a, or 14b (hereinafter referred to as backflow). If backflow occurs, important components inside the stove body 2 may burn, or the stainless steel top plate 3 may be scorched and discolored. Therefore, in order to quickly and reliably detect backflow, the gas stove 1 of this embodiment employs the following structure.

[0051] Figure 3 This is a perspective view showing the structure used for detecting backflow in the gas stove 1 of this embodiment. First, in Figure 3 (a) shows the enlarged view of the end sides of the main burner mixing tube 13 and the auxiliary burner mixing tube 14. In the gas stove 1 of this embodiment, as described above, the auxiliary burner mixing tube 14 extends to the right without overlapping the main burner mixing tube 13, and the ends of the main burner mixing tube 13 and the auxiliary burner mixing tube 14 are separated to the left and right. Furthermore, as shown, the gas stove 1 has a cover 30 that houses the opening 13a of the end of the main burner mixing tube 13, the first opening 14a and the second opening 14b of the end of the auxiliary burner mixing tube 14 inside the cover 30. Inside the cover 30, a bimetallic thermal switch 32, serving as a temperature-sensing element, is disposed near (above) the first opening 14a and the second opening 14b. Furthermore, in Figure 3 In the diagram, the interior is visible through a viewing shield 30. Furthermore, the circuit structure, including the bimetallic thermal switch 32, will be described later using other accompanying drawings.

[0052] In this embodiment, the cover 30 is formed, for example, by sheet metal processing of a metal sheet such as galvanized steel sheet. The upper surface plate 30a, shaped like an inverted letter L, integrally covers the area above the opening 13a of the main burner mixing pipe 13 and the areas above the first opening 14a and the second opening 14b of the auxiliary burner mixing pipe 14. The left end (main burner mixing pipe 13 side) of the upper surface plate 30a in the figure is bent downward to form a left side wall 30b, and the right end (auxiliary burner mixing pipe 14 side) is bent downward to form a right side wall 30c. A mounting portion is provided at the lower end of the left side wall 30b and the right side wall 30c, which is bent horizontally and provided in a base (not shown) inside the stove body 2.

[0053] Furthermore, on the front side of the cover 30 in the figure, the leading edge of the upper surface plate 30a is bent downward to form a front surface wall 30d. Below this front surface wall 30d, a gap is provided relative to the base for accommodating the main burner branch pipe 20a and the auxiliary burner branch pipe 20b. In this embodiment, the front surface wall 30d has a fixing part on the auxiliary burner mixing pipe 14 side for fixing the bimetallic thermal switch 32.

[0054] Furthermore, on the inside of cover 30 in the diagram, such as Figure 3 As shown by the dashed line in (b), the rear edge of the upper surface plate 30a is bent downward to form: a rear surface wall 30e adjacent to the right side wall 30c and opposite to the front surface wall 30d; a back surface wall 30f adjacent to the left side wall 30b and opposite to the front surface wall 30d and located behind the rear surface wall 30e; and a connecting wall 30g connecting the rear surface wall 30e and the back surface wall 30f and opposite to the left side wall 30b.

[0055] By using such a cover 30 to pre-cover the opening 13a of the main burner mixing tube 13 and the first opening 14a and the second opening 14b of the auxiliary burner mixing tube 14, the spread of flames ejected from the openings 13a, 14a and 14b within the stove body 2 can be suppressed, regardless of whether backflow occurs in the main burner 11 or the auxiliary burner 12.

[0056] Figure 4 This is a top view showing the positional relationship between the main burner mixing tube 13, the auxiliary burner mixing tube 14, and the shroud 30 of this embodiment, as viewed from above. In this embodiment, the left side wall 30b of the shroud 30 is erected at an acute angle (40 degrees in the illustrated example) relative to the extension direction of the main burner mixing tube 13, indicated by the dashed arrow in the figure, on the side away from the auxiliary burner mixing tube 14, and faces the opening 13a of the main burner mixing tube 13. Furthermore, the left side wall 30b of this embodiment corresponds to the "sealing wall" of the present invention.

[0057] The front surface wall 30d, adjacent to the left side wall 30b, is similarly positioned facing the opening 13a of the main burner mixing tube 13, extending from the side edge of the left side wall 30b towards the end of the auxiliary burner mixing tube 14 (bimetallic thermal switch 32), and is vertically positioned at an acute angle (40 degrees in the illustrated example) relative to the extending direction of the main burner mixing tube 13. Furthermore, the angle between the left side wall 30b and the front surface wall 30d is also an acute angle (80 degrees in the illustrated example). In addition, the front surface wall 30d of this embodiment corresponds to the "guide wall" of the present invention.

[0058] The rear surface wall 30e, adjacent to the right side wall 30c and opposite to the front surface wall 30d, is not parallel to the front surface wall 30d. The gap between the front surface wall 30d and the rear surface wall 30e narrows as it approaches the bimetallic thermal switch 32 from the main burner mixing tube 13 side. Furthermore, the rear surface wall 30f, adjacent to the left side wall 30b and opposite to the front surface wall 30d, is arranged approximately perpendicularly to the left side wall 30b from the side opposite to the front surface wall 30d. In this embodiment, the rear surface wall 30e corresponds to the "auxiliary wall" of the present invention, and the rear surface wall 30f corresponds to the "blocking wall" of the present invention.

[0059] Figure 5 This diagram illustrates the use of a bimetallic thermal switch 32 to detect backflow when either the main burner 11 or the auxiliary burner 12 occurs. The diagram shows an enlarged view of the inner side of the shroud 30 from a top perspective. Firstly, in the case of backflow in the auxiliary burner 12, as mentioned earlier, the amount of fuel gas supplied to the auxiliary burner 12 is less than that supplied to the main burner 11. Therefore, the flame ejected from the first opening 14a and the second opening 14b (mainly the second opening 14b) of the auxiliary burner mixing tube 14 is smaller. However, since the bimetallic thermal switch 32 of this embodiment is located near (above) the first opening 14a and the second opening 14b, the backflow flame from the auxiliary burner 12 easily reaches the bimetallic thermal switch 32, which is then heated, enabling rapid and reliable detection of backflow on the auxiliary burner 12 side. Furthermore, the blank arrows in the diagram schematically indicate the backflow flame diffusing into the shroud 30.

[0060] On the other hand, in the case of backflow occurring in the main burner 11, the flame ejected from the opening 13a of the main burner mixing tube 13 is larger than that from the auxiliary burner 12. However, since the bimetallic thermal switch 32 is located away from the opening 13a, the shroud 30 is used to guide the backflowing flame. When backflow occurs due to blockage of the main burner flame opening 11a, in addition to unburned gas produced by incomplete combustion, fuel gas injected from the nozzle of the main burner distribution pipe 20a also leaks from the opening 13a toward the extension direction of the main burner mixing tube 13. In this embodiment, the opening 13a opens toward the triangular stagnation space S surrounded by the upper surface plate 30a, the left side wall 30b, and the front surface wall 30d of the shroud 30. Furthermore, by arranging the left side wall 30b at an acute angle relative to the extension direction of the main burner mixing tube 13, the diffusion of unburned gas and fuel gas along the left side wall 30b can be suppressed compared to the case where it is arranged at an obtuse angle. Similarly, by arranging the front surface wall 30d at an acute angle relative to the extension direction of the main burner mixing tube 13, compared to an obtuse angle arrangement, the diffusion of unburned gas and fuel gas along the front surface wall 30d can be suppressed. Therefore, unburned gas and fuel gas tend to accumulate in the stagnation space S, where they combust momentarily. As a result, the flame diffuses from the stagnation space S along the front surface wall 30d toward the auxiliary burner mixing tube 14. In this way, the backfire flame from the main burner 11 is guided by the shroud 30 (front surface wall 30d) to the bimetallic thermal switch 32, which is then heated, thereby enabling rapid and reliable detection of backfire on the main burner 11 side.

[0061] Furthermore, in the cover 30 of this embodiment, the angle between the left side wall 30b and the front surface wall 30d is set to an acute angle. Compared with the case where it is set to an obtuse angle, unburned gas and fuel gas become easier to accumulate in the stagnation space S. As a result, the momentum of the flame diffusing from the stagnation space S to the side of the auxiliary burner mixing tube 14 can be ensured. Therefore, the arrival accuracy toward the bimetallic thermal switch 32 can be improved.

[0062] As described above, in the gas stove 1 of this embodiment, a bimetallic thermal switch 32 provided inside the cover 30 is used to quickly and reliably detect backflow in either the main burner 11 or the auxiliary burner 12.

[0063] Furthermore, in the cover 30 of this embodiment, a rear surface wall 30e is provided opposite to the front surface wall 30d. The bimetallic thermal switch 32 is located between the front surface wall 30d and the rear surface wall 30e, and the gap between the front surface wall 30d and the rear surface wall 30e narrows as it approaches the bimetallic thermal switch 32 from the main burner mixing tube 13 side. For the backflow flame from the main burner 11 side, it passes through the space S between the front surface wall 30d and the rear surface wall 30e and moves towards the bimetallic thermal switch 32. Because the gap between the front surface wall 30d and the rear surface wall 30e narrows, the flame is concentrated and its momentum increases. Therefore, the accuracy of reaching the bimetallic thermal switch 32 can be improved, and the arrival speed can be accelerated.

[0064] Furthermore, in the cover 30 of this embodiment, a back wall 30f is provided, which is adjacent to the left side wall 30b and opposite to the front surface wall 30d. In the back injection on the main burner 11 side, if the unburned gas and fuel gas accumulated in the stagnation space S are momentarily combusted, although the flame spreads from the stagnation space S along the left side wall 30b in the opposite direction to the front surface wall 30d, the back wall 30f can be used to block the spread of the flame. In addition, a connecting wall 30g is provided, which connects the back wall 30f and the rear surface wall 30e. The flame, which has nowhere to go because it is blocked by the back wall 30f and the connecting wall 30g, spreads along the rear surface wall 30e to the auxiliary burner mixing tube 14 side. Therefore, the accuracy of the flame from the back injection on the main burner 11 side reaching the bimetallic thermal switch 32 can be further improved.

[0065] Figure 6 This is an explanatory diagram showing the circuit structure of the gas stove 1 of this embodiment, including the bimetallic thermal switch 32. As shown, the bimetallic thermal switch 32 of this embodiment is connected in series in the circuit that connects the thermocouple 50 and the electromagnetic safety valve 21 that controls the gas piping 20. For the thermocouple 50, in order to detect the flame (ignition) of the auxiliary burner 12, its temperature measuring contact at the top is positioned facing one of the auxiliary burner flame ports 12a.

[0066] The electromagnetic safety valve 21 has an inlet chamber 40 connected to the upstream side of a gas piping 20 and an outlet chamber 41 connected to the downstream side of the gas piping 20. A valve seat 43 with a valve hole 42 is provided between the inlet chamber 40 and the outlet chamber 41. A valve body 44 is provided in the inlet chamber 40, which closes the valve hole 42 by abutting against the valve seat 43. The valve body 44 is fixed to the movable shaft of the solenoid 45 and is forced by a first force-applying spring 46 in the direction of abutting against the valve seat 43. The figure shows the closed state with the valve body 44 abutting against the valve seat 43. Even if the solenoid 45 is energized, it cannot move the valve body 44 away from the valve seat 43, but it can use electromagnetic force to keep the valve body 44, which has been separated from the valve seat 43 by external force, in the open state.

[0067] Additionally, the electromagnetic safety valve 21 is provided with a rod 47 that can slide along the same axis as the movable axis of the solenoid 45. This rod 47 is used to transmit the pressing operation of the operating button 7 from the outlet chamber 41 side to the valve body 44. The rod 47 is not fixed to the valve body 44 and is exerted with force by the second force-applying spring 48 in a direction away from the valve body 44 (to the right in the figure).

[0068] When the user presses the operation button 7 to ignite the stove burner 10, the lever 47 overcomes the force of the second force-applying spring 48 and is pressed into the valve body 44. Furthermore, the lever 47, abutting against the valve body 44, overcomes the force of the first force-applying spring 46, causing the valve body 44 to move away from the valve seat 43, thereby opening the electromagnetic safety valve 21. Thus, when the electromagnetic safety valve 21 is open, fuel gas is supplied to the stove burner 10, and combustion of the mixed gas begins in the auxiliary burner 12. The flame emitted from the auxiliary burner flame port 12a heats the tip of the thermocouple 50.

[0069] As is well known, thermocouple 50 generates a thermoelectric electromotive force when heated, and this thermoelectric electromotive force is supplied to the solenoid 45 of the electromagnetic safety valve 21 connected to thermocouple 50. Therefore, even after the operation button 7 is released and the rod 47 is moved away from the valve body 44 by the force of the second force-applying spring 48, the electromagnetic safety valve 21 can still be kept open by the electromagnetic force of the solenoid 45 in the energized state.

[0070] In this embodiment, the bimetallic thermal switch 32 is connected in series with a circuit that supplies the thermoelectric potential of the thermocouple 50 to the electromagnetic safety valve 21. As described above, if backflow occurs in either the main burner 11 or the auxiliary burner 12, and its flame reaches the bimetallic thermal switch 32, the contacts of the heated bimetallic thermal switch 32 change from a closed state to an open state as the predetermined temperature rises, thereby detecting the backflow. Thus, when the contacts of the bimetallic thermal switch 32 become open, the thermoelectric potential of the thermocouple 50 supplied to the solenoid 45 of the electromagnetic safety valve 21 is cut off, and therefore, the electromagnetic safety valve 21 becomes closed, rapidly stopping the supply of fuel gas to the stove burner 10.

[0071] The gas stove 1 of this embodiment has been described above, but the present invention is not limited to the above embodiment and can be implemented in various ways without departing from its spirit.

[0072] For example, in the aforementioned embodiment, the angle between the left side wall 30b and the front surface wall 30d is set to an acute angle. However, if the left side wall 30b and the right side wall 30c are respectively arranged at acute angles relative to the extension direction of the main burner mixing tube 13, the angle between the left side wall 30b and the front surface wall 30d can also be an obtuse angle. However, if the angle between the left side wall 30b and the front surface wall 30d is preset to an acute angle as in the aforementioned embodiment, unburned gas and fuel gas become easier to accumulate in the retention space S compared to the case where it is set to an obtuse angle, which can improve the accuracy of the backflow flame from the main burner 11 reaching the bimetallic thermal switch 32 from the retention space S. Such an angle between the left side wall 30b and the front surface wall 30d is particularly preferably in the range of 60 degrees to 90 degrees. In addition, the connection portion between the left side wall 30b and the front surface wall 30d does not necessarily have to be an angle, and can also be made curved (with rounded corners).

[0073] Furthermore, in the aforementioned embodiment, a bimetallic thermal switch 32 was used as the thermal element. However, the thermal element is not limited to this; it could also be a temperature sensor with a thermistor. The resistance of the thermistor changes according to temperature. Therefore, in the electrical unit connected to the temperature sensor, the occurrence of backflow is determined based on the resistance value (temperature detection value), and the power supply to the solenoid safety valve 21 is stopped according to the instruction from the electrical unit, thereby closing the solenoid safety valve 21. However, if a bimetallic thermal switch 32 is used as the thermal element as in the aforementioned embodiment, the bimetallic thermal switch 32 is heated by the backflow flame, causing its contacts to open. This allows the power supply to the solenoid safety valve 21 to be directly cut off, enabling the solenoid safety valve 21 to close quickly. In addition, since an electrical unit is not required, the product cost of the gas stove 1 can be reduced.

[0074] Furthermore, in the aforementioned embodiment, the thermoelectric potential supplied by the thermocouple 50 is used as a power source to maintain the open state of the electromagnetic safety valve 21. However, the power source is not limited to this; it can also be a dry cell battery or a commercial power source. However, if the thermoelectric potential generated by the thermocouple 50, which is used to detect the flame (ignition) of the auxiliary burner 12, is used as a power source to maintain the open state of the electromagnetic safety valve 21, as in the aforementioned embodiment, no additional power source is required. Therefore, the gas stove 1 can be used without any limitations in terms of power supply.

Claims

1. A gas stove equipped with a main burner and an auxiliary burner with a smaller flame than the main burner, wherein if fuel gas is injected from nozzles at the top of each branch path (which branches into two) into an opening at the end of a main burner mixing pipe extending from the main burner and into an opening at the end of an auxiliary burner mixing pipe extending in a direction different from the main burner mixing pipe, a mixture of fuel gas and air is ejected through the main burner mixing pipe and from a plurality of flame ports of the main burner, and the mixture is ejected through the auxiliary burner mixing pipe and from a plurality of flame ports of the auxiliary burner, causing the mixture to burn and heat a cooking container, the gas stove being characterized in that… The gas stove has the following features: A cover, which houses the openings of the main burner mixing tube and the auxiliary burner mixing tube on its inner side; and A thermal element, located within the enclosure near the opening of the auxiliary burner mixing tube. The cover has: The upper surface plate integrally covers the area above the opening of the main burner mixing tube and the area above the opening of the auxiliary burner mixing tube; A sealing wall, which is erected at an acute angle relative to the extending direction of the main burner mixing tube on the side away from the auxiliary burner mixing tube, and faces the opening of the main burner mixing tube; and The guide wall is arranged from the side edge of the sealing wall toward the direction of the heat-sensitive element facing the opening of the main burner mixing tube, and is erected at an acute angle relative to the extension direction of the main burner mixing tube.

2. The gas stove according to claim 1, characterized in that, The angle between the blocking wall and the guiding wall is an acute angle.

3. The gas stove according to claim 1 or 2, characterized in that, The cover has an auxiliary wall opposite to the guide wall, and the thermal element is located between the auxiliary wall and the guide wall. The gap between the guide wall and the auxiliary wall narrows as it moves closer to the thermistor element from the mixing tube side of the main burner.

4. The gas stove according to claim 1 or 2, characterized in that, The cover has a blocking wall that is disposed opposite to the guide wall from a side edge of the blocking wall on the side opposite to the guide wall.

5. The gas stove according to claim 1 or 2, characterized in that, The gas stove has an electromagnetic safety valve, which opens and closes the upstream portion of the gas passage compared to the branch section. The thermal element is a bimetallic thermal switch whose contacts change from a closed state to an open state as the predetermined temperature rises. The bimetallic thermal switch is connected in series to the power supply circuit that supplies power to maintain the open state of the electromagnetic safety valve.

6. The gas stove according to claim 5, characterized in that, A thermocouple is installed facing the flame port of the auxiliary burner. The power source is the thermoelectric potential generated by the thermocouple.

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