Gas burner and heat cooker

Abstract

To provide a gas burner having a burner body 4 and a burner head 5 on the burner body 4, the burner body 4 having therein a distribution chamber 42 into which gas flows via a gas inlet pipe, and the burner head 5 having a burner port 51 opening on an outer peripheral face of the burner head 5 and a distribution passage 52 for distributing the gas from the distribution chamber 42 into the burner port 51, in which an entry of boil-over into the distribution chamber 42 is suppressed and a deterioration in burner performance due to accumulation of the boil-over is prevented.SOLUTION: The distribution passage 52 has a radially expansion part 522 that expands in a radial direction from an inflow part 521 in a radially inward direction in which the gas from the distribution chamber 42 flows toward the burner port 51. The radially expansion part 522 has an inner passage part 522a, an outer passage part 522b, and an intermediate passage part 522c. On at least a part in a radial direction of a lower face of the inner passage part 522a, a portion positioned above a height of a portion positioned at the uppermost of a lower face of the outer passage part 522b is provided.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas burner including 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 including this gas burner. [Background technology]

[0002] A known example of this type of gas burner is described in Patent Document 1. This burner has a burner body with a distribution chamber inside, into which gas flows via a gas inlet pipe, and a burner head with a plurality of flame holes spaced apart in the circumferential direction and opening on the outer circumferential surface of the burner head, and a distribution passage that distributes gas from the distribution chamber to the flame holes. The distribution passage extends upward from the distribution chamber, and the flame holes are in contact with the outer circumferential surface of the distribution passage.

[0003] In such gas burners, if boil-over occurs, the boil-over may enter the burner head through the flame holes. The boil-over that enters the burner head then falls down through the distribution passage into the distribution chamber in the burner body. In this case, the distribution chamber is difficult to clean, so boil-over accumulates in the distribution chamber, deteriorating the combustion performance of the gas burner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-124271 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, the present invention aims to provide a gas burner and a heating cooker equipped with this gas burner that can prevent boil-over from entering the distribution chamber within the burner body, thereby avoiding deterioration of combustion performance due to the accumulation of boil-over. [Means for solving the problem]

[0006] In order to solve the above problems, a first invention of the present application provides 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 inside into which gas flows via the gas inlet pipe; the burner head has a plurality of flame holes that open on the outer peripheral surface of the burner head and are spaced apart in the circumferential direction; and a distribution passage that distributes gas from the distribution chamber to the flame holes, wherein the distribution passage has an inlet portion on the radially inner side into which gas flows from the distribution chamber, and a radially expanding portion that expands radially from the inlet portion toward the flame holes, and the radially expanding portion has an inner passage portion near the first portion, an outer passage portion near the flame holes, and an intermediate passage portion connecting the inner passage portion and the outer passage portion, and wherein at least a radial part of the lower surface of the inner passage portion is provided that is located higher than the height of the uppermost part of the lower surface of the outer passage portion. A second invention of the present application is a cooking device characterized by including the gas burner of the first invention.

[0007] According to this invention (first invention), even if boil-over enters the outer passage part of the radially expanding part of the distribution passage from the burner holes, the boil-over is blocked by the higher part of the lower surface of the inner passage part of the radially expanding part, preventing the boil-over from entering the inlet part of the distribution passage and the distribution chamber in the burner body.The boil-over remains near the burner holes, which are easy to clean, and it is possible to avoid deterioration of the combustion performance of the gas burner due to boil-over accumulation in the distribution chamber in the burner body, which is difficult to clean.

[0008] In addition, in the present invention, it is desirable that the entire lower surface of the inner passage portion of the radially expanding portion of the distribution passage be positioned above the height of the upper edge of the burner hole, thereby more effectively preventing boil-over from passing over the inner passage portion and entering the distribution chamber from the inlet portion of the distribution passage.

[0009] Furthermore, in the present invention, it is desirable that the burner head has an eave portion that projects radially outward above the burner holes, and that a downwardly extending annular first hanging wall portion be suspended from the outer periphery of the underside of the eave portion. This prevents boil-over that falls onto the burner head from flowing around the outer periphery of the burner head and into the burner holes. The height of the lower end of the first hanging wall portion should be higher than the height of the upper edge of the burner holes so that the flame formed in the burner holes does not hit the first hanging wall portion.

[0010] In this case, it is desirable to provide a downwardly extending annular second hanging wall portion hanging down from the underside of the eaves portion, positioned radially inward from the first hanging wall portion. The height of the lower end of the second hanging wall portion is above the height of the upper edge of the burner hole but below the height of the lower end of the first hanging wall portion. This allows the first and second hanging wall portions to doubly prevent boil-over from getting around the burner hole, improving the effectiveness of preventing boil-over from entering the burner hole.

[0011] When hydrogen gas, which has a high combustion rate, is used as the fuel gas, a flashback suppression member must be incorporated into the burner head to suppress flashback. However, if the flashback suppression member is clogged with boil-over liquid, the gas cannot be properly distributed to the flame holes, resulting in ignition failure. Therefore, in the present invention, the entire lower surface of the inner passage portion of the radially expanding portion of the distribution passage is positioned above the height of the upper edge of the flame holes. If the inner passage portion or the distribution passage has a vertical passage portion extending upward from the distribution chamber toward the inlet portion, it is desirable to install a flashback suppression member made of a porous material made of metal or ceramic in the vertical passage portion so that the gas passing through the flashback suppression member is distributed to the flame holes. This prevents boil-over liquid from penetrating into the area where the flashback suppression member is located. Therefore, the flashback suppression member is not clogged with boil-over liquid, preventing ignition failure.

[0012] Furthermore, in this case, 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 to cause diffusion combustion, stable combustion performance can be ensured even if the fuel gas is hydrogen gas. [Brief explanation of the drawings]

[0013] [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. 2 is an exploded perspective view of the gas burner according to the embodiment. [Figure 4] FIG. 10 is an enlarged cross-sectional view of a main part of a gas burner according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1 and 2 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.

[0015] The gas burner A comprises a 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 a 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.

[0016] 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 formed therein 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 also has a plurality of flame holes 51 that open onto the outer circumferential surface of the burner head 5 and are spaced apart in the circumferential direction, and a distribution passage 52 that distributes the fuel gas from the distribution chamber 42 to these flame holes 51. The fuel gas is then ejected from the flame holes 51 and diffused and combusted.

[0017] The structure of the burner head 5 will be explained in more detail with reference to Figure 3. The burner head 5 is composed of two upper and lower members: a lower member 5L that contacts the burner body 4, and an upper member 5U that is placed on the lower member 5L. These two members 5L and 5U are fastened together at three circumferential locations with short screws 5a to assemble the burner head 5. The assembled burner head 5 is then fastened to the burner body 4 with long screws 5b at three circumferential locations that are out of phase with the short screws 5a. After fastening the burner head 5 to the burner body 4, a cover plate 6 is placed on the upper member 5U to conceal the short screws 5a and long screws 5b.

[0018] The distribution passage 52 has a radially inward inlet portion 521 into which gas flows from the distribution chamber 42 in the burner body 4, and a radially expanding portion 522 that expands radially from the inlet portion 521 toward the flame holes 51. A cylindrical through-hole that penetrates vertically and communicates with the distribution chamber 42 is formed in the lower member 5L. This through-hole forms a vertical passage portion 523 that is one of the components of the distribution passage 52 and extends upward from the distribution chamber 42 toward the inlet portion 521. Furthermore, connecting portions 523a that connect the outer peripheral wall and inner peripheral wall of the through-hole are provided at multiple locations circumferentially in the lower part of the through-hole. The radially expanding portion 522 is also defined between the lower member 5L and the upper member 5U. The radially expanding portion 522 has an inner passage portion 522a closer to the inlet portion 521, an outer passage portion 522b closer to the burner holes 51, and an intermediate passage portion 522c connecting the inner passage portion 522a and the outer passage portion 522b.

[0019] More specifically, the upper surface portion of the lower member 5L radially outward from the inlet portion 521 is formed in a stepped shape, with the portion of this upper surface near the inlet portion 521 being higher and the outer periphery of this upper surface being lower. Multiple stepped protrusions 5La, which are lowered radially outward, are provided at intervals in the circumferential direction on the outer periphery of this upper surface portion. An annular wall 5Ua that contacts the upper surfaces of all of the stepped protrusions 5La is vertically provided on the outer periphery of the lower surface of the upper member 5U. An inner passage portion 522a is defined between the portion of the upper surface portion of the lower member 5L radially outward from the inlet portion 521 near the inlet portion 521 and the lower surface of the upper member 5U. The gaps between the stepped protrusions 5La, 5La, covered by the annular wall 5Ua, define, from radially inward, an intermediate passage portion 522c, an outer passage portion 522b, and a flame hole 51 at the radially outer end. Here, the entire lower surface of the inner passage portion 522a is located higher than the height of the upper edge of the burner hole 51, and naturally the entire lower surface of the inner passage portion 522a is located higher than the height of the uppermost portion of the lower surface of the outer passage portion 522b. In this embodiment, since the outer passage portion 522b is horizontal, the entire lower surface of the outer passage portion 522b is the uppermost portion of the lower surface. In addition, the intermediate passage portion 522c is inclined downward from the inner passage portion 522a toward the outer passage portion 522b.

[0020] According to this embodiment, even if boil-over enters the outer passage portion 522b of the radially expanding portion 522 of the distribution passage 52 from the flame holes 51, the boil-over is blocked outside the inner passage portion 522a, the underside of which is located higher than the height of the underside of the outer passage portion 522b, and the boil-over can be prevented from entering the inner passage portion 522a, the inlet portion 521 of the distribution passage 52, the vertical passage portion 523, or the distribution chamber 42 in the burner body 4. The boil-over remains in the outer passage portion 522b near the flame holes 51, which is easy to clean, and it is possible to avoid a deterioration in the combustion performance of the gas burner A due to the accumulation of boil-over in the vertical passage portion 523 of the distribution passage 52 and the distribution chamber 42 in the burner body 4, which are difficult to clean.

[0021] Furthermore, in this embodiment, the burner head 5 is provided with an eave portion 53 that extends radially outward above the flame holes 51. Specifically, the outer periphery of the upper member 5U of the burner head 5 extends radially outward beyond the flame holes 51 to form the eave portion 53. A downwardly extending annular first hanging wall portion 531 is suspended from the outer periphery of the underside of the eave portion 53. This causes boil-over that flows down the outer periphery of the burner head 5 to drip from the lower end of the first hanging wall portion 531, preventing the boil-over from reaching the flame holes 51.

[0022] Further, an annular second hanging wall portion 532 extending downward is suspended from the underside of overhanging portion 53, positioned radially inward from first hanging wall portion 531. This allows first hanging wall portion 531 and second hanging wall portion 532 to doubly prevent boil-over from getting around to burner hole 51, improving the effectiveness of preventing boil-over from entering burner hole 51. The height of the lower ends of first and second hanging wall portions 531, 532 is higher than the height of the upper edge of burner hole 51 so that the flame formed in burner hole 51 does not come into contact with them. The height of the lower end of second hanging wall portion 532 is equal to or lower than the height of the lower end of first hanging wall portion 531.

[0023] In the gas burner A of this embodiment, as described above, fuel gas is ejected from the flame holes 51 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 52 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 operation, a mixture of fuel gas and air is generated in the distribution passage 52 and the distribution chamber 42, which may cause flashback inside the burner. Therefore, in this embodiment, an annular flashback suppression member 54 is provided in the inner passage portion 522a so that gas that passes through the flashback suppression member 54 is distributed to the flame holes 51.

[0024] The flashback suppression member 54 is made of a porous material made of metal or ceramic. Specifically, the flashback suppression member 54 is made of a porous material with numerous minute gaps equal to or smaller than the quenching distance, such as a sintered body made by sintering a laminate of metal fibers or metal beads, a knitted body made by knitting metal fibers, or porous ceramic. Furthermore, a plurality of protrusions 5Lb are provided at intervals in the circumferential direction on the inner periphery of the upper surface portion of the lower member 5L of the burner head 5, which faces the inner passage portion 522a, to abut against the inner periphery of the flashback suppression member 54 and position the flashback suppression member 54.

[0025] If boil-over seeps into and clogs flashback suppression member 54, gas cannot be distributed properly to flame holes 51, resulting in ignition failure. However, in this embodiment, flashback suppression member 54 is disposed in inner passage portion 522a, the entire lower surface of which is located above the height of the upper edge of flame holes 51, and therefore boil-over can be prevented from seeping into the area where flashback suppression member 54 is disposed. Therefore, flashback suppression member 54 will not become clogged due to boil-over seepage, and ignition failure can be prevented.

[0026] 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 second flashback suppression member 43 is installed on the bottom surface of the upper distribution chamber 422 so that a small hole 431 is located directly above the lower distribution chamber 421, and in this state is fastened to the burner body 4 with a plurality of screws 432.

[0029] 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. However, 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 51. However, when hydrogen gas is used as the fuel gas, a diffusion combustion burner is desirable in order to suppress flashback. Furthermore, in the above embodiment, the flashback suppression member 54 is interposed in the inner passage portion 522a of the radially expanding portion 522 of the distribution passage 52. However, as shown in FIG. 4, it is also possible to interpose the flashback suppression member 54 in the vertical passage portion 523 of the distribution passage 52.

[0030] Furthermore, in the above embodiment, the entire lower surface of the inner passage portion 522a of the radially expanding portion 522 of the distribution passage 52 is located higher than the height of the upper edges of the flame holes 51, but this is not essential, and it is sufficient that at least a part of the lower surface of the inner passage portion 522a in the radial direction is provided with a portion that is located higher than the height of the uppermost portion of the lower surface of the outer passage portion 522b. For example, as shown in Fig. 4, if the inner passage portion 522a and the outer passage portion 522b are each inclined upward toward the outside in the radial direction, it is sufficient that the radially outer end of the lower surface of the inner passage portion 522a is located higher than the height of the radially outer end, which is the uppermost portion of the lower surface of the outer passage portion 522b. Alternatively, the intermediate passage portion 522c may be located at the lowest position, the outer passage portion 522b may have an inclined portion inclined upward radially outward from the intermediate passage portion 522c, and the inner passage portion 522a may have an inclined portion inclined upward radially inward from the intermediate passage portion 522c to a position higher than the upper end of the inclined portion of the outer passage portion 522b, so that the entire radially expanding portion 522 has a V-shaped bent downward. [Explanation of symbols]

[0031] A...gas burner, 3...gas inlet pipe, 4...burner body, 42...distribution chamber, 5...burner head, 51...flame hole, 52...distribution passage, 521...inlet section, 522...radial expansion section, 522a...inner passage section, 522b...outer passage section, 522c...intermediate passage section, 523...vertical passage section, 53...eaves section, 531...first hanging wall section, 532...second hanging wall section, 54...flashback suppression member.

Claims

1. A gas burner comprising: a burner body rising from a 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 a plurality of flame holes that open on the outer peripheral surface of the burner head and are spaced apart in the circumferential direction, and a distribution passage that distributes gas from the distribution chamber to the flame holes, a distribution passage having an inlet portion on the radially inner side into which gas flows from the distribution chamber, and a radially expanding portion that expands radially from the inlet portion toward the burner holes, and the radially expanding portion having an inner passage portion near the inlet portion, an outer passage portion near the burner holes, and an intermediate passage portion connecting the inner passage portion and the outer passage portion, and a portion located higher than the height of the uppermost portion of the lower surface of the outer passage portion is provided on at least a radial part of the lower surface of the inner passage portion.

2. 2. A gas burner according to claim 1, wherein the entire lower surface of said inner passage portion is located above the height of the upper edge of said flame hole.

3. 3. A gas burner according to claim 1, wherein the burner head has a visor portion extending radially outward above the flame hole, and a ring-shaped first hanging wall portion extending downward is attached to the outer periphery of the lower surface of the visor portion, and the height of the lower end of the first hanging wall portion is higher than the height of the upper edge of the flame hole.

4. 4. The gas burner according to claim 3, wherein a downwardly extending annular second hanging wall portion is suspended from the underside of the eave portion, positioned radially inward from the first hanging wall portion, and the height of the lower end of the second hanging wall portion is above the height of the upper edge of the flame hole and is below the height of the lower end of the first hanging wall portion.

5. 3. A gas burner according to claim 2, wherein a flashback suppression member made of a porous material made of metal or ceramic is interposed in the inner passage portion, and gas passing through the flashback suppression member is distributed to the flame holes.

6. 3. A gas burner according to claim 2, wherein the distribution passage has a vertical passage portion extending upward from the distribution chamber toward the inlet portion, and a flashback suppression member made of a porous material made of metal or ceramic is interposed in the vertical passage portion, and the gas passing through the flashback suppression member is distributed to the flame holes.

7. 7. A gas burner according to claim 5, wherein the gas flowing in from the gas inlet pipe is fuel gas not mixed with primary air, and the fuel gas is ejected from the flame holes to cause diffusion combustion.

8. A cooking device comprising the gas burner according to any one of claims 1, 2, 5 and 6.

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