Gas burner and heating cooker

Abstract

To provide a gas burner which includes a burner body 4 rising from the downstream end of a gas inflow pipe 3 into which fuel gas is supplied from a gas nozzle 32, and a burner head 5 placed on the burner body 4, the burner body 4 having a distribution chamber 42 inside, into which gas flows via the gas inflow pipe 3, the burner head 5 having an annular wall 51 exposed to the outer peripheral face of the burner head, the annular wall being provided with a plurality of burner ports spaced therefrom in the peripheral direction for jetting gas from the distribution chamber 42, capable of preventing back-fire to the gas nozzle 32 in the case of igniting operation in the state of forgetting to mount the burner head 5 on the burner body 4.SOLUTION: In the distribution chamber 42 or the gas inflow pipe 3, a back-fire suppression member 43 is provided having a ventilation part 431 where gas passes.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas burner having a burner body rising from the downstream end of a gas inlet pipe and a burner head placed on the burner body, and a cooking appliance equipped with this gas burner. [Background technology]

[0002] Originally, in this type of gas burner, the burner body has a distribution chamber inside into which gas flows in through a gas inlet pipe, and the burner head has an annular wall exposed on the outer surface of the burner head, and this annular wall has multiple flame holes spaced circumferentially to eject gas from the distribution chamber.

[0003] As a countermeasure against flashback, a stack of partition plates is arranged in the burner head with gaps in the vertical direction, and gas from the distribution chamber is ejected from the flame holes through the gaps between the partition plates of the stack, as disclosed in Patent Document 1. In this case, flashback can be prevented by making the gaps between the partition plates equal to or smaller than the quenching distance.

[0004] The burner head can be removed from the burner body for cleaning. Therefore, after cleaning, the user may forget to attach the burner head to the burner body and then perform the ignition operation. In this case, the stack of partition plates installed in the burner head as in the conventional example is useless. Furthermore, if the fuel gas is a gas with a high combustion rate, such as hydrogen gas, backfire may occur through the distribution chamber in the burner body and the gas inlet pipe to the gas nozzle at the upstream end of the gas inlet pipe, potentially causing the gas nozzle to burn out. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-124271 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above, the present invention aims to provide a gas burner that can prevent backfire up to the gas nozzle when the ignition operation is performed with the burner head left attached to the burner body, and a heating cooker equipped with this gas burner. [Means for solving the problem]

[0007] In order to solve the above problems, the first invention of the present application is a gas burner comprising a burner body rising from the downstream end of a gas inlet pipe and a burner head placed on the burner body, wherein the burner body has a distribution chamber inside into which gas flows in via the gas inlet pipe, and the burner head has an annular wall exposed to the outer surface of the burner head, and this annular wall has a plurality of flame holes spaced apart circumferentially to eject gas from the distribution chamber, and wherein a flashback suppression member having a ventilation section through which gas passes is provided in the distribution chamber or the gas inlet pipe. A second invention of the present application is a cooking device characterized by including the gas burner of the first invention.

[0008] According to the present invention (first invention), even if the burner head is not attached to the burner body and ignition is performed, flashback is prevented by the flashback suppression member provided in the distribution chamber in the burner body or in the gas inlet pipe. Therefore, flashback can be prevented up to the gas nozzle facing the upstream end of the gas inlet pipe, and the risk of burning out the gas nozzle can be eliminated.

[0009] In the present invention, the flashback suppression member is preferably made of a sheet metal member having a plurality of small holes formed therein to serve as ventilation portions, thereby reducing the cost of the flashback suppression member.

[0010] Furthermore, in the present invention, the distribution chamber is composed of a lower distribution chamber into which gas flows from the gas inlet pipe and an upper distribution chamber located above the lower distribution chamber. The upper distribution chamber is surrounded by an annular upper distribution chamber bottom portion having a lower distribution chamber communication port communicating with the lower distribution chamber, an upper distribution chamber outer wall portion erected on the outer periphery of the upper distribution chamber bottom portion, and an upper distribution chamber inner wall portion erected on the inner periphery of the upper distribution chamber bottom portion. The flashback suppression member is preferably installed on the bottom portion of the upper distribution chamber so that the vent is located above the lower distribution chamber communication port. According to this, when the burner head is installed on the burner body and the ignition operation is performed without attaching the burner head to the burner body, the location of the flame is generally between the outer wall portion and the inner wall portion of the upper distribution chamber, away from the bottom portion of the upper distribution chamber. Therefore, the flashback suppression member installed on the bottom portion of the upper distribution chamber is less likely to be directly burned by the flame, preventing thermal deformation of the flashback suppression member. Therefore, there is no risk of a gap being created between the flashback suppression member and the bottom surface of the upper distribution chamber due to thermal deformation of the flashback suppression member, which would impair the flashback suppression effect.

[0011] Furthermore, when the flashback suppression member is installed on the bottom surface of the upper distribution chamber, it is desirable to provide a positioning means for positioning the flashback suppression member relative to the upper distribution chamber. This prevents the vent of the flashback suppression member from shifting from a position above the lower distribution chamber communication port, ensuring that gas can flow from the lower distribution chamber to the upper distribution chamber via the vent.

[0012] Furthermore, it is desirable to interpose a heat insulating material with a lower thermal conductivity than the material of the burner body between the bottom of the upper distribution chamber and the flashback suppression member. This allows the heat conduction from the burner body to the flashback suppression member to be suppressed by the heat insulating material, and thermal deformation of the flashback suppression member can be more effectively prevented.

[0013] Furthermore, in the present invention, if the gas flowing in from the gas inlet pipe is fuel gas that is not mixed with primary air and is ejected from the flame holes for diffusion combustion, flashback can be more effectively suppressed even if the fuel gas is hydrogen gas. [Brief explanation of the drawings]

[0014] [Figure 1]1 is a perspective view of a main part of a cooking device equipped with a gas burner according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional side view taken along line II-II in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional front view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional plan view taken along line IV-IV in FIG. 2. [Figure 5] FIG. 2 is an exploded perspective view of the gas burner according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] 1 to 3 show a cooking appliance equipped with a gas burner A according to an embodiment of the present invention. The cooking appliance has a top plate 1 that covers the top surface of a cooking appliance body (not shown). A trivet 2 having a plurality of trivet claws 21 is placed on the top plate 1 so as to surround a burner opening 11 that faces the gas burner A opened in the top plate 1. The gas burner A is also provided with an ignition electrode Aa and a thermocouple Ab for flame detection.

[0016] The gas burner A comprises an annular burner body 4 supported by a support frame 12 fixed to the cooking appliance body and rising from the downstream end of a gas inlet pipe 3 located under the top plate 1 toward a burner opening 11, and an annular burner head 5 placed on the burner body 4. The upstream end of the gas inlet pipe 3 is connected to a gas outlet 31a of a casing 31 of a valve unit for fuel gas. A gas nozzle 32 for injecting fuel gas is provided at the downstream end of the valve unit, which communicates with the gas outlet 31a. Therefore, the gas flowing into the gas inlet pipe 3 is fuel gas without primary air being mixed in. Hydrogen gas is used as the fuel gas. Note that "hydrogen" includes not only pure hydrogen but also hydrogen containing small amounts of additives for flavoring, etc.

[0017] A port portion 41 is protrudingly formed at one location around the lower periphery of the burner body 4. The port portion 41 has a connection port 41a for a joint 33 provided at the downstream end of the gas inlet pipe 3. The burner body 4 has an annular distribution chamber 42 inside, into which gas (fuel gas) flows from the gas inlet pipe 3. The burner head 5 has an annular wall 51 exposed to the outer circumferential surface of the burner head 5. This annular wall 51 has a plurality of flame holes 52 spaced apart in the circumferential direction, through which the gas (fuel gas) from the distribution chamber 42 is ejected. The fuel gas is ejected from the flame holes 52 and undergoes diffusion combustion. Small flame holes 52a for flame stabilization and flame transfer are provided between circumferentially adjacent flame holes 52, 52. The burner head 5 also has a distribution passage 53 inside, which distributes gas from the distribution chamber 42 to the flame holes 52 and the small flame holes 52a.

[0018] As shown in Figure 4, the burner holes 52 are formed so that the opening area of ​​the burner holes relative to the outer peripheral surface of the annular wall 51 is larger than the opening area of ​​the burner holes relative to the inner peripheral surface of the annular wall 51. This makes the density of gas ejected from the burner holes 52 (amount of gas per unit area) on the outer peripheral surface side of the annular wall 51 lower than the density of gas flowing into the burner holes 52 on the inner peripheral surface side of the annular wall 51. The lower density of the ejected gas reduces the energy density at the burner holes 52 during ignition, thereby reducing the noise during ignition. In this embodiment, the circumferential length of the burner holes 52 is longer on the outer peripheral surface side of the annular wall 51 than on the inner peripheral surface side. However, it is also possible to make the vertical width of the burner holes 52 larger on the outer peripheral surface side of the annular wall 51 than on the inner peripheral surface side, so that the opening area of ​​the burner holes relative to the outer peripheral surface of the annular wall 51 is larger than the opening area of ​​the burner holes relative to the inner peripheral surface of the annular wall 51.

[0019] The structure of the burner head 5 will be described in more detail with reference to Figure 5. The burner head 5 is composed of three upper and lower members: an annular lower member 5L that contacts the burner body 4, an annular intermediate member 5M that is placed on the lower member 5L, and an annular upper member 5U that covers the intermediate member 5M from above. These three members 5L, 5M, and 5U are fastened together by short screws 5a at two circumferential positions near the inner periphery to form the burner head 5. The assembled burner head 5 is then fastened to the burner body 4 by long screws 5b at two circumferential positions near the inner periphery that are in a different phase from the short screws 5a.

[0020] An outer cylindrical portion 5La and an inner cylindrical portion 5Lb are vertically disposed on the lower surface of the lower member 5L, and are fitted to the outer and inner peripheries of the burner body 4. The lower member 5L is also formed with a plurality of arc-shaped through-holes 531 at intervals in the circumferential direction, which penetrate in the vertical direction and communicate with the distribution chamber 42. The upper portions of the through-holes 531 are continuously annular in the circumferential direction.

[0021] The upper surface of the intermediate member 5M is provided with the above-mentioned annular wall 51, which is located on the outer periphery and has the flame holes 52, and furthermore, a downwardly recessed annular groove 532 is formed between the annular wall 51 and the inner half. The intermediate member 5M also has a plurality of communicating holes 533, which are arc-shaped in plan view and open to the inner periphery of the groove 532, formed at intervals in the circumferential direction and communicate with the through hole 531 of the lower member 5L. The distribution passage 53 is composed of the through hole 531, the communicating holes 533, and the groove 532.

[0022] In the gas burner A of this embodiment, as described above, fuel gas is ejected from the flame holes 52 for diffusion combustion, so that flashback into the interior of the burner can be suppressed during combustion, even if the fuel gas is hydrogen gas. However, since the distribution passage 53 and the distribution chamber 42 are replaced with air when not in use, when fuel gas flows in from the gas inlet pipe 3 during ignition, a mixture of fuel gas and air is generated in the distribution passage 53 and the distribution chamber 42, which may cause flashback inside the burner. Therefore, in this embodiment, a flashback suppression member 54 is provided in the distribution passage 53 so that gas passing through the flashback suppression member 54 is distributed to the flame holes 52. The flashback suppression member 54 is made of a porous material made of metal or ceramic.

[0023] Furthermore, when wind blows toward the burner holes 52 from the outside, the wind may pass from one burner hole 52 to another burner hole 52 through the space inside the burner head 5, causing a flashback. Therefore, in this embodiment, an annular flashback suppression member 54 is installed in the recessed groove 532 of the distribution path 53 so that its outer circumferential surface abuts against the inner circumferential surface of the annular wall 51. In this way, the flashback suppression member 54 functions as an obstacle that prevents wind from passing through the space inside the burner head 5, making it possible to suppress flashbacks caused by the passing of wind.

[0024] The burner head 5 is provided with a plurality of stopper portions 55 spaced apart in the circumferential direction, positioned in the recessed groove 532 of the intermediate member 5M and abutting the inner peripheral surface of the flashback suppression member 54. By providing the stopper portions 55 in this manner, even if a user inserts a rod-shaped cleaning tool for cleaning the flame hole into the flame hole 52 during maintenance to push the flashback suppression member 54 inward, the flashback suppression member 54 will not fall off into the burner.

[0025] Furthermore, if a rod-shaped cleaning tool for cleaning the flame holes is inserted too forcefully into the flame holes 52, a hole may be created in the flashback suppression member 54. Therefore, the stopper portion 55 is provided at a circumferential position that coincides with the flame holes 52. With this, even if a hole is created in the flashback suppression member 54 as described above, the hole will be blocked by the stopper portion 55, and the flashback suppression effect will not be impaired. The circumferential length of the stopper portion 55 is slightly longer than the circumferential length of the flame holes 52 on the inner circumferential surface of the annular wall 51. Furthermore, because a cleaning tool cannot be inserted too forcefully into the small flame holes 52a, the stopper portion 55 is not provided at a circumferential position that coincides with the small flame holes 52a.

[0026] Incidentally, for cleaning purposes, the burner head 5 may be removed from the burner body 4 by loosening the fastening with the long screw 5b. After cleaning, the user may perform an ignition operation while forgetting to attach the burner head 5 to the burner body 4. In this case, there is a risk that a backfire will occur through the distribution chamber 42 in the burner body 4 and the gas inlet pipe 3 to the gas nozzle 32, causing the gas nozzle 32 to burn out.

[0027] Therefore, in this embodiment, a second flashback suppression member 43 having a ventilation portion through which gas passes is provided in the distribution chamber 42. With this, even if the ignition operation is performed with the burner head 5 forgotten to be attached to the burner body 4, the flashback is blocked by the second flashback suppression member 43, preventing flashback up to the gas nozzle 32 and eliminating the risk of burning out the gas nozzle 32. Note that although the second flashback suppression member 43 can also be made of a porous body like the above-mentioned flashback suppression member 54, in this embodiment, in order to reduce costs, the second flashback suppression member 43 is made of a sheet metal member having a plurality of small holes 431 formed therein, which serve as ventilation portions and have a hole diameter (for example, 0.6 mm) equal to or smaller than the quenching distance.

[0028] Here, the distribution chamber 42 is composed of a lower distribution chamber 421 into which gas flows in from the gas inlet pipe 3, and a wide upper distribution chamber 422 located above the lower distribution chamber 421. The upper distribution chamber 422 is surrounded by an annular upper distribution chamber bottom 4221 having a lower distribution chamber communication port 4221a communicating with the lower distribution chamber 421, an upper distribution chamber outer peripheral wall 4222 erected on the outer periphery of the upper distribution chamber bottom 4221, and an upper distribution chamber inner peripheral wall 4223 erected on the inner periphery of the upper distribution chamber bottom 4221. The second flashback suppression member 43 is laid on the upper distribution chamber bottom 4221 so that a small hole 431 serving as a vent is located above the lower distribution chamber communication port 4221a, and in this state is fastened to the burner body 4 with a plurality of screws 432.

[0029] According to this, when the burner head 5 is forgotten to be attached to the burner body 4 and an ignition operation is performed, the location of the flame that occurs, except for the initial stage of ignition, is generally the area between the outer peripheral wall 4222 and the inner peripheral wall 4223 of the upper distribution chamber 422, which is far from the upper distribution chamber bottom 4221. Therefore, the second flashback suppression member 43 installed on the upper distribution chamber bottom 4221 is less likely to be directly burned by the flame, and thermal deformation of the second flashback suppression member 43 can be prevented. Therefore, there is no risk of a gap being created between the upper distribution chamber bottom 4221 due to thermal deformation of the second flashback suppression member 43, which would impair the flashback suppression effect.

[0030] This embodiment further includes a positioning means 44 for positioning the second flashback suppression member 43 relative to the upper distribution chamber 422. The positioning means 44 is composed of notches 441 formed at two locations around the inner periphery of the second flashback suppression member 43 and ridges 442 protruding from two locations around the outer periphery of the upper distribution chamber inner peripheral wall portion 4223. The ridges 442 are engaged with the notches 441 to position the second flashback suppression member 43 relative to the upper distribution chamber 422. Positioning the second flashback suppression member 43 in this manner prevents the small hole 431, which serves as a vent, from shifting from a position above the lower distribution chamber communication port 4221a, ensuring that gas can flow reliably from the lower distribution chamber 421 to the upper distribution chamber 422 through the small hole 431.

[0031] Furthermore, a heat insulating material 45 having a lower thermal conductivity than the material (e.g., aluminum alloy) of the burner body 4 is interposed between the upper distribution chamber bottom portion 4221 and the second flashback suppression member 43. This makes it possible to suppress heat conduction from the burner body 4 to the second flashback suppression member 43 by the heat insulating material 45, thereby more effectively preventing thermal deformation of the second flashback suppression member 43.

[0032] Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited thereto. For example, in the above embodiment, the gas burner A is a diffusion combustion burner, but it is also possible to use a premixing burner in which the gas inlet pipe 3 is a mixing pipe type and a mixture of fuel gas and primary air is ejected from the flame holes 52. However, when hydrogen gas is used as the fuel gas, it is desirable to use a diffusion combustion burner in order to suppress flashback. Furthermore, in the above embodiment, the second flashback suppression member 43 is disposed in the distribution chamber 42 in the burner body 4, but it is also possible to dispose the second flashback suppression member 43 in the gas inlet pipe 3. [Explanation of symbols]

[0033] A...gas burner, 3...gas inlet pipe, 4...burner body, 42...distribution chamber, 421...lower distribution chamber, 422...upper distribution chamber, 4221...bottom surface of upper distribution chamber, 4221a...lower distribution chamber communication port, 4222...outer outer wall of upper distribution chamber, 4223...inner outer wall of upper distribution chamber, 43...second flashback suppression member (flashback suppression member), 431...small hole, 44...positioning means, 45...insulating material, 5...burner head, 51...annular wall, 52...flame hole.

Claims

1. A gas burner comprising a burner body rising from the downstream end of a gas inlet pipe and a burner head mounted on the burner body, wherein the burner body has a distribution chamber therein into which gas flows via the gas inlet pipe, and the burner head has an annular wall exposed on the outer circumferential surface of the burner head, and a plurality of flame holes for ejecting gas from the distribution chamber are provided at intervals in the circumferential direction on the annular wall, 1. A gas burner comprising: a flashback suppression member having a vent portion through which gas passes, disposed in a distribution chamber or a gas inlet pipe.

2. 2. The gas burner according to claim 1, wherein the flashback suppression member is made of a metal plate member having a plurality of small holes formed therein to serve as the ventilation portion.

3. The gas burner according to claim 1, characterized in that the distribution chamber is composed of a lower distribution chamber into which gas flows in from the gas inlet pipe and an upper distribution chamber located above the lower distribution chamber, and the upper distribution chamber is surrounded by an annular upper distribution chamber bottom portion having a lower distribution chamber communication port communicating with the lower distribution chamber, an upper distribution chamber outer wall portion erected on the outer periphery of the upper distribution chamber bottom portion, and an upper distribution chamber inner wall portion erected on the inner periphery of the upper distribution chamber bottom portion, and the flashback suppression member is laid on the bottom portion of the upper distribution chamber so that the ventilation portion is located above the lower distribution chamber communication port.

4. 4. A gas burner according to claim 3, further comprising positioning means for positioning said flashback suppression member relative to said upper distribution chamber.

5. 4. The gas burner according to claim 3, wherein a heat insulating material having a lower thermal conductivity than a material forming said burner body is interposed between said bottom surface of said upper distribution chamber and said flashback suppression member.

6. 2. A gas burner according to claim 1, wherein the gas flowing in from said gas inlet pipe is fuel gas not mixed with primary air, and the fuel gas is ejected from said flame holes to cause diffusion combustion.

7. A cooking device comprising the gas burner according to any one of claims 1 to 6.

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