Gas burner, and heat-cooking apparatus

Abstract

In a gas burner (A) that includes a burner body (4), and a burner head (5) placed on the burner body and having therein a distribution chamber (42), the burner head having a plurality of flame holes (51) that is opened in an outer circumferential surface of the burner head, and a distribution passage (52), the gas burner can suppress the entry of the boiling-over into the distribution chamber and avoid the deterioration of the combustion performance due to the accumulation of the boiling-over. The distribution passage has a radial-direction spreading part (522) that spread in a radial direction from an inlet part (521), in which a gas flows from a distribution chamber (42) and which is positioned inward in the radial direction, toward each of a plurality of flame holes (51). The radial-direction spreading part has an inside passage part (522a), an outside passage part (522b), and an intermediate passage part (522c). With at least one part in the radial direction of a lower surface of the inside passage part, a part that is positioned upward from a height of a part that is positioned at the uppermost of a lower surface of the outside passage part is provided.

Description

Technical Field

[0001] The invention relates to a gas burner that includes a burner body standing up from a downstream end of a gas inlet pipe and a burner head placed on the burner body, and to a heat-cooking apparatus that includes the gas burner.Background Art

[0002] Conventionally, such a gas burner as described in Patent Document No. 1, for example, has been known as this type. The conventionally known gas burner has a burner body having therein a distribution chamber into which a gas flows through a gas inlet pipe, and a burner head having a plurality of flame holes, which opens at an outer circumferential surface of the burner head and is provided at intervals in a circumferential direction, and a distribution passage that distributes the gas from the distribution chamber to each of the flame holes. In addition, a distribution passage extends upward from the distribution chamber, and each flame hole comes into contact with an outer circumferential surface of the distribution passage.

[0003] In such a gas burner, when boiling-over occurs, the boiling-over sometimes enters the burner head from the flame holes. Then, the boiling-over that enters the burner head drops onto the distribution chamber in the burner head through the distribution passage. In this case, since it is difficult to clean the distribution chamber, the boiling-over will accumulate in the distribution chamber, resulting in deterioration of a combustion performance of the gas burner. A related gas burner having the features specified in the preamble of claim 1 is known from Patent Document No. 2.References

[0004] Patent Document No. 1: JP2021-124271 A Patent Document No. 2: US 2023 / 228416 A1 Summary of Invention Technical Problems

[0005] In view of the foregoing problem, the invention provides a gas burner that can suppress the entry of the boiling-over into the distribution chamber in the burner body and avoid the deterioration of the combustion performance due to the accumulation of the boiling-over, and a heat-cooking apparatus that includes the gas burner.Solution to Problems

[0006] In order to solve the aforementioned problem, a first invention presupposes a gas burner A, including, a burner body 4 standing up from a downstream end of a gas inlet pipe 3, the burner body having therein a distribution chamber 42 in which a gas flows through the gas inlet pipe; and a burner head 5 placed on the burner body, the burner head having a plurality of flame holes 51 that are opened in an outer circumferential surface of the burner head and provided at intervals in a circumferential direction, and a distribution passage 52 that distributes the gas from the distribution chamber to each of the flame holes. In the gas burner, the distribution passage has an inlet part 521 in which the gas flows from the distribution chamber and which is positioned inward in a radial direction, and a radial-direction spreading part 522 that spreads in the radial direction from the inlet part to each flame hole, the radial-direction spreading part having an inside passage part 522a near the inlet part, an outside passage part 522b near the flame holes, and an intermediate passage part 522c connecting the inside passage part with the outside passage part. According to the invention, in the gas burner, at least one portion in the radial direction of a lower surface of the inside passage part is positioned upward from a height of an uppermost portion of a lower surface of the outside passage part. In other words, with at least one part in the radial direction of a lower surface of the inside passage part, a part that is positioned upward from a height of a part that is positioned at the uppermost of a lower surface of the outside passage part is provided.

[0007] A second invention provides a heat-cooking apparatus that includes the aforementioned gas burner of the first invention.

[0008] According to the invention (a first invention), even if the boiling-over enters from each flame hole into the outside passage part of the radial-direction spreading part of the distribution passage, the boiling-over can be blocked at a high part of the lower surface of the inside passage part of the radial-direction spreading part. Accordingly, it can be suppressed that the boiling-over enters the inlet part of the distribution passage and the distribution chamber in the burner body. The boiling-over stays in a part near each flame hole, where it is easy to clean. As a result, it is possible to prevent deterioration of a combustion performance of the gas burner due to accumulation of the boiling-over in the distribution chamber in the burner body, which is difficult to clean.

[0009] In addition, in the invention, it is desirable that an entire lower surface of the inside passage part of the radial-direction spreading part in the distribution passage is positioned upward from a height of an upper edge of each flame hole. According to this, the penetration of the boiling-over from the inlet part of the distribution passage into the distribution chamber beyond the inside passage part can be suppressed more effectively.

[0010] Furthermore, in the invention, it is desirable that the burner head has an eave part 53 extending outward in the radial direction above each flame hole, and an annular first hanging wall part 531 extending downward is suspended at an outer circumferential part of a lower surface of the eave part. According to this, the boiling-over that dropped onto the burner head can be prevented from running through the outer circumferential part of the burner head and around to each flame hole. It should be noted that a height of a lower end of the first hanging wall part should be set upward from the upper edge of each flame hole so that a flame formed in each flame hole cannot come into contact with the first hanging wall part.

[0011] In this case, it is desirable that an annular second hanging wall part 532, which is positioned more inward in the radial direction than the first hanging wall part and extends downward, is suspended at the lower surface of the eave part. It should be noted that a height of a lower end of the second hanging wall part should be set higher than the height of the upper edge of each flame hole and should be set equal to or lower than that of the lower end of the first hanging wall part. According to this, the issue that running of the boiling-over around to each flame hole can be doubly suppressed by the first and second hanging wall parts. As a result, the effects of preventing the entry of the boiling-over into each flame hole can be improved.

[0012] Meanwhile, in a case where hydrogen, which has a faster combustion speed, is used as a fuel gas, it is necessary to assemble a backfire suppressing member 54 in the burner head to suppress backfire. However, if clogging occurs due to the penetration of the boiling-over into the backfire suppressing member, the gas will be difficult to be adequately distributed, resulting in ignition failure. In view of the foregoing, in the invention, in a case where the entire lower surface of the inside passage part of the radial-direction spreading part of the distribution passage is positioned more upward than the upper edge of each flame hole, and where the distribution passage has a vertical-direction passage part 523 that extends upward from the distribution chamber toward the inlet part, it is desirable that the backfire suppressing member, which is constituted by a porous body consisting of a metal or a ceramic, is interposed in the inside passage part or in the vertical-direction passage part, and is configured that the gas passed through the backfire suppressing member is distributed to each flame hole. According to this, the boiling-over can be suppressed to penetrate into a disposed part of the backfire suppressing member. Therefore, the backfire suppressing member is not clogged by the penetration of the boiling-over, and the ignition failure can be prevented.

[0013] Furthermore, in this case, the gas burner is configured that when the gas flowing from the gas inlet pipe is used as the fuel gas, which is not mixed with primary air, and the fuel gas is ejected from each flame hole and diffusely combusted, even though the fuel gas is hydrogen, it is possible to ensure a stable combustion performance.Brief Description of the Drawings

[0014] FIG. 1 is a perspective view of a major part of a heat-cooking apparatus including a gas burner of an embodiment of the invention. FIG. 2 is a cross-sectional view cut at II-II of FIG. 1. FIG. 3 is a perspective view showing a disassembled state of the gas burner in the embodiment. FIG. 4 is an enlarged cross-sectional view of a major of a gas burner in another embodiment. Description of Embodiments

[0015] FIGS. 1, 2 show a heat-cooking apparatus that includes a gas burner A of an embodiment of the invention. The heat-cooking apparatus A has a top plate 1 covering an upper surface of an apparatus body omitted to show. A trivet 2 having a plurality of trivet pawls 21 is placed on the top plate 1 to surround a burner opening 11 that is opened in the top plate 1 and makes the gas burner A faced. In addition, an ignition electrode Aa and a thermocouple Ab for detecting a flame are attached to the gas burner A.

[0016] The gas burner A includes a burner body 4 that stands up from a downstream end of the gas inlet pipe 3 that is disposed below the top plate 1 toward the burner opening 11 and is supported by a supporting frame 12 fixed to the apparatus body, and a burner head 5 placed on the burner body 4. An upstream end of the gas inlet pipe 3 is connected to a gas outlet part 31a of a casing 31 of a valve unit for fuel gas. A gas nozzle 32 ejecting the fuel gas is provided at a downstream end part, which communicates with the gas outlet part 31a, of the valve unit. Therefore, a gas flowing in the gas inlet pipe 3 becomes a fuel gas that is not mixed with primary air. Hydrogen is used as a fuel gas. It should be noted that "hydrogen" includes not only pure hydrogen but also mixtures containing small amounts of additives for odorization or the like.

[0017] From one portion around a lower part of the burner body 4, a port part 41 is protruded, in which a connecting opening 41a for a joint 33 that is provided at a downstream end of the gas inlet pipe 3 is formed. The burner body 4 has therein an annular distribution chamber 42 in which the gas (fuel gas) from the gas inlet pipe 3 flows. In addition, the burner head 5 has a plurality of flame holes 51, each of which opens in an outer circumferential surface of the burner head 5 and is provided at intervals in a circumferential direction 4, and a distribution passage 52 that distributes the fuel gas from the distribution chamber 42 to each of the flame holes 51. Then, the fuel gas ejects from each flame hole 51 and combusts diffusely.

[0018] With reference also to FIG. 3, a structure of the burner head 5 is described in more detail. The burner head 5 is constituted by two members arranged in a vertical direction, one of which a lower member 5L coming into contact with the burner body 4 and the other of which is an upper member 5U placed on the lower member 5L. These two members 5L, 5U are fastened with a short screw 5a at three portions in the circumferential direction to be assembled as a burner head 5. The assembled burner head 5 is fastened to the burner body 4 with a long screw 5b at three portions in the circumferential direction. Topology of three portions at which the long screw 5b is screwed is different from that of the three portions at which the short screw 5a is screwed. After fastening the burner head 5 to the burner body 4, a covering plate 6 is placed on the upper member 5U, and both the short screws 5a and the long screws 5b are concealed.

[0019] A distribution passage 52 has an inlet part 521 in which the gas from the distribution chamber 42 in the burner body 4 flows and which is positioned inward in a radial direction, and a radial-direction spreading part 522 that spreads in the radial direction from the inlet part 521 toward each flame hole 51. A tubular through-hole that communicates to the distribution chamber 42 and pierces vertically is formed in the lower member 5L, and a vertical-direction passage part 523 that extends upward from the distribution chamber 42 toward the inlet part 521 and is one of the constituent elements of the distribution passage 52 is constituted by the through-hole. It should be noted that at a plurality of portions in the circumferential direction at a lower part in the through-hole, connecting portions 523a that connect an outer circumferential wall and an inner circumferential wall of the through-hole are provided. In addition, the radial-direction spreading part 522 is defined between the lower member 5L and the upper member 5U. The radial-direction spreading part 522 has an inside passage part 522a near the inlet part 521, an outside passage part 522b near the flame holes 51, and an intermediate passage part 522c connecting the inside passage part 522a and the outside passage part 522b.

[0020] More specifically, an upper-surface part of the lower member 5L, which is positioned on an outer side in the radial direction from the inlet part 521, is formed into a stepped shape of which a part near the inlet part 521 of the upper-surface part is high and an outer circumferential part of the upper-surface part is lowered, and a plurality of stepped projection parts 5La, of which an outer side in the radial direction is lowered, is provided at the outer circumferential part of the upper-surface part at intervals in the circumferential direction. In addition, an annular wall 5Ua that comes into contact with upper surfaces of all the stepped projection parts 5La is suspended from the outer circumferential part of a lower surface of the upper member 5U. Then, it is configured that the inside passage part 522a is defined between a part near the inlet part 521of the upper-surface part of the lower member 5L on a more outer side in the radial direction than the inlet part 521 and the lower surface of the upper member 5U. Furthermore, the intermediate passage part 522c, the outside passage part 522b, and each flame hole 51 positioned at an outer end in the radial direction are constituted in a subsequence from an inner side in the radial direction by a clearance that is positioned between adjacent stepped projection parts 5La, 5La that are covered by the annular wall 5Ua. Here, an entire lower surface of the inside passage part 522a is positioned more upward from a height of an upper edge of each flame hole 51. Naturally, the entire lower-surface of the inside passage part 522a is positioned upward from a height of a part, which is positioned at an uppermost position, of a lower surface of the outside passage part 522b. It should be noted that in the embodiment, the outside passage part 522b is positioned horizontally. Therefore, the entire lower-surface of the outside passage part 522b is a part that is positioned at an uppermost position in the lower surface thereof. In addition, the intermediate passage part 522c is inclined downward from the inside passage part 522a to the outside passage part 522b.

[0021] According to the embodiment, even if the boiling-over enters from each flame hole 51 into outside passage part 522b of the radial-direction spreading part 522 of the distribution passage 52, the boiling-over is blocked on the outer side of the inside passage part 522a, of which the lower surface is positioned upward from the height of the lower surface of the outside passage part 522b. Accordingly, it can be suppressed that the boiling-over enters the inside passage part 522a, the inlet part 521 of the distribution passage 52, the vertical-direction passage part 523, and the distribution chamber 42 in the burner body 4. The boiling-over stays in the outside passage part 522b near the flame holes 51, where it is easy to clean. As a result, it is possible to prevent deterioration of a combustion performance of the gas burner A due to accumulation of the boiling-over in the vertical-direction passage part 523 of the distribution passage 52 and the distribution chamber 42 in the burner body 4, where it is difficult to clean.

[0022] In addition, in the embodiment, an eave part 53 extending outward in the radial direction above each flame hole 51 is provided with the burner head 5. Specifically, the eave part 53 is constituted by extending an outer circumferential part of the upper member 5U of the burner head 5 outward in the radial direction from each flame hole 51. Then, an annular first hanging wall part 531 extending downward is suspended at the outer circumferential part of a lower surface of the eave part 53. This allows the boiling-over to run down through an outer circumferential part of the burner head 5 and to drop from the lower end of the first hanging wall part 531. Therefore, it can be prevented the boing-over from running around to each flame hole 51.

[0023] Furthermore, an annular second hanging wall part 532 that is positioned more inward in the radial direction than the first hanging wall part 531 and extends downward is suspended at the lower surface of the eave part 53. According to this, running around to each flame hole 51 of the boiling-over can be doubly suppressed by the first hanging wall part 531 and the second hanging wall part 532. As a result, the effect of preventing the entry of the boiling-over into each flame hole 51can be improved. It should be noted that a height of a lower end of each of the first and second hanging wall parts 531, 532 is positioned upward from the height of the upper edge of each flame hole 51 so that a flame formed in each flame hole 51 does not come into contact with either of first and second hanging walls 531, 532. In addition, the height of the lower end of the second hanging wall part 532 is equal to or lower than the height of the lower end of the first hanging wall part 531.

[0024] Meanwhile, in the gas burner A of the embodiment, as aforementioned, since the fuel gas is caused to eject from each flame hole 51 and is combusted diffusely, even if the fuel gas is hydrogen, backfire toward an inside of the gas burner A during combustion can be suppressed. However, since the inner spaces of the distribution passage 52 and distribution chamber 42 that are not in use are replaced with air, if the fuel gas flows in the inner spaces from the gas inlet pipe 3 due to an ignition operation, an air-fuel mixture of the fuel gas with air is produced in the distribution passage 52 and distribution chamber 42, and there is feasibility that the backfire toward the inside of the gas burner A occurs. Therefore, the embodiment is configured that an annular backfire suppressing member 54 is interposed in the inside passage part 522a to distribute the gas passing through the backfire suppressing member 54 to each flame hole 51.

[0025] The backfire suppressing member 54 is constituted by a porous body consisting of a metal or a ceramic. Specifically, the backfire suppressing member 54 is constituted by the porous body with innumerable minute-clearances equal to or smaller than a fire-extinguishing distance, such as a sintered body by sintering a laminated body of metal fibers or metal beads, a knitted body by knitting metal fibers into a knitted shape, or a porous ceramic. In addition, a plurality of protruding parts 5Lb, each of which comes into contact with an inner circumferential surface of the backfire suppressing member 54 to position the backfire suppressing member 54, is provided with an inner circumferential part of the upper-surface part, which faces an inside passage part 522a, of the lower member 5L of the burner head 5 at intervals in the circumferential direction.

[0026] Here, if the boiling-over penetrates into the backfire suppressing member 54 and clogging occurs, the gas cannot be adequately distributed to each flame hole 51, resulting in ignition failure. However, in the embodiment, since the backfire suppressing member 54 is interposed in the inside passage part 522a of which the entire lower surface is positioned upward from the height of the upper edge of each flame hole 51, the boiling-over can be suppressed from entering a disposed part of the backfire suppressing member 54. Therefore, clogging of the backfire suppressing member 54 due to the penetration of the boiling-over does not occur, thus preventing the ignition failure.

[0027] Incidentally, for cleaning, the burner head 5 is sometimes removed from the burner body 4 by loosening the long screws 5b. After cleaning, a user may attempt the ignition operation in a state where the user forgets to reattach the burner head 5 to the burner body 4. In this case, there is an issue that the backfire passes through the distribution chamber 42 in the burner body 4 and the inside of the gas inlet pipe 3, reaches the gas nozzle 32, and causes the gas nozzle 32 to be damaged by burning.

[0028] Therefore, in the embodiment, a second backfire-suppressing member 43 having a ventilation part through which the gas passes is provided in the distribution chamber 42. According to this, even if the ignition operation is performed in the state where the burner head 5 is forgotten to attach to the burner body 4, the backfire is blocked by the second backfire-suppressing member 43. Accordingly, the backfire can be prevented from reaching the gas nozzle 32, thereby eliminating a risk of damage to the gas nozzle 32 due to burning. It should be noted that although the second backfire-suppressing member 43 may be made of a porous body like the aforementioned backfire suppressing member 54, in the embodiment, the second backfire-suppressing member 43 is constituted by a sheet-metal member having a plurality of small holes 431 to reduce cost. Each of the small holes 431 functions as the ventilation part, and a hole diameter is equal to or smaller than the fire-extinguishing distance (for example, 0.6mm).

[0029] Here, the distribution chamber 42 is constituted by a lower distribution chamber 421 into which the gas flows from the gas inlet pipe 3 and a wider upper distribution chamber 422 that is positioned above the lower distribution chamber 421. Then, the second backfire-suppressing member 43 is laid on a bottom surface of the upper distribution chamber 422 so that each small hole 431 is positioned at a just upper part of the lower distribution chamber 421, and, in this state, is fastened to the burner body 4 with a plurality of screws 432.

[0030] The embodiment of the invention is described referring to the figures in the above. However, the invention is not limited to the embodiment. For example, in the aforementioned embodiment, although the gas burner A is a burner of a diffusion combustion type, provided that the gas inlet pipe 3 is of a mixing-pipe type, the burner may be of a premixing type in which an air-fuel mixture of the fuel gas with air ejects from each flame hole 51. However, in a case where hydrogen is used as a fuel gas, it is desirable that the burner is of the diffusion combustion type in view of suppressing the backfire. In addition, in the aforementioned embodiment, although a backfire suppressing member 54 is interposed in the inside passage part 522a of the radial-direction spreading part 522 of the distribution passage 52, alternatively, it may be possible that, as shown in FIG. 4, the backfire suppressing member 54 is interposed in the vertical-direction passage part 523 of the distribution passage 52.

[0031] Furthermore, in the aforementioned embodiment, although the entire lower surface of the inside passage part 522a of the radial-direction spreading part 522 of the distribution passage 52 is positioned upward from the height of the upper edge of each flame hole 51, this is not essential. It is sufficient that at least a portion in the radial direction of the lower surface of the inside passage part 522a is positioned upward from the height of the portion positioned at the uppermost position of the lower surface of the outside passage part 522b. For example, as shown in FIG. 4, in a case where the inside passage part 522a and the outside passage part 522b are inclined upward so as to be directed outward in the radial direction, respectively, it is sufficient that an outer-side end part in the radial direction of the lower surface of the inside passage part 522a is positioned upward from the height of the outer-side end in the radial direction that is the part positioned at the upmost position in the lower surface of the outside passage part 522b. In addition, it may also be possible for an entire radial-direction spreading part 522 to be formed into a downwardly curved shape that is V-shaped. In this case, the entire the radial-direction spreading part 522 has the following structure: the intermediate passage part 522c is positioned at the lowest position; the outside passage part 522b has an inclined part that is inclined upwardly to the outside in the radial direction from the intermediate passage part 522c; and the inside passage part 522a has an inclined part that is upwardly inclined and extends toward the inner side in the radial direction from the intermediate passage part 522c to a position higher than the upper end of the inclined part of the outside passage part 522b.Explanation of symbols

[0032] AGas burner 3Gas inlet pipe 4Burner body 42Distribution chamber 5Burner head 51Flame hole 52Distribution passage 521Inlet part 522Radial-direction spreading part 522aInside passage part 522bOutside passage part 522cIntermediate passage part 523Vertical-direction passage part 53Eave part 531First hanging wall part 532Second hanging wall part 54Backfire suppressing member

Examples

Embodiment Construction

[0015]FIGS. 1, 2 show a heat-cooking apparatus that includes a gas burner A of an embodiment of the invention. The heat-cooking apparatus A has a top plate 1 covering an upper surface of an apparatus body omitted to show. A trivet 2 having a plurality of trivet pawls 21 is placed on the top plate 1 to surround a burner opening 11 that is opened in the top plate 1 and makes the gas burner A faced. In addition, an ignition electrode Aa and a thermocouple Ab for detecting a flame are attached to the gas burner A.

[0016]The gas burner A includes a burner body 4 that stands up from a downstream end of the gas inlet pipe 3 that is disposed below the top plate 1 toward the burner opening 11 and is supported by a supporting frame 12 fixed to the apparatus body, and a burner head 5 placed on the burner body 4. An upstream end of the gas inlet pipe 3 is connected to a gas outlet part 31a of a casing 31 of a valve unit for fuel gas. A gas nozzle 32 ejecting the fuel gas is provided at a downstr...

Technical Field

[0001] The invention relates to a gas burner that includes a burner body standing up from a downstream end of a gas inlet pipe and a burner head placed on the burner body, and to a heat-cooking apparatus that includes the gas burner.Background Art

[0002] Conventionally, such a gas burner as described in Patent Document No. 1, for example, has been known as this type. The conventionally known gas burner has a burner body having therein a distribution chamber into which a gas flows through a gas inlet pipe, and a burner head having a plurality of flame holes, which opens at an outer circumferential surface of the burner head and is provided at intervals in a circumferential direction, and a distribution passage that distributes the gas from the distribution chamber to each of the flame holes. In addition, a distribution passage extends upward from the distribution chamber, and each flame hole comes into contact with an outer circumferential surface of the distribution passage.

[0003] In such a gas burner, when boiling-over occurs, the boiling-over sometimes enters the burner head from the flame holes. Then, the boiling-over that enters the burner head drops onto the distribution chamber in the burner head through the distribution passage. In this case, since it is difficult to clean the distribution chamber, the boiling-over will accumulate in the distribution chamber, resulting in deterioration of a combustion performance of the gas burner. A related gas burner having the features specified in the preamble of claim 1 is known from Patent Document No. 2.References

[0004] Patent Document No. 1: JP2021-124271 A Patent Document No. 2: US 2023 / 228416 A1 Summary of Invention Technical Problems

[0005] In view of the foregoing problem, the invention provides a gas burner that can suppress the entry of the boiling-over into the distribution chamber in the burner body and avoid the deterioration of the combustion performance due to the accumulation of the boiling-over, and a heat-cooking apparatus that includes the gas burner.Solution to Problems

[0006] In order to solve the aforementioned problem, a first invention presupposes a gas burner A, including, a burner body 4 standing up from a downstream end of a gas inlet pipe 3, the burner body having therein a distribution chamber 42 in which a gas flows through the gas inlet pipe; and a burner head 5 placed on the burner body, the burner head having a plurality of flame holes 51 that are opened in an outer circumferential surface of the burner head and provided at intervals in a circumferential direction, and a distribution passage 52 that distributes the gas from the distribution chamber to each of the flame holes. In the gas burner, the distribution passage has an inlet part 521 in which the gas flows from the distribution chamber and which is positioned inward in a radial direction, and a radial-direction spreading part 522 that spreads in the radial direction from the inlet part to each flame hole, the radial-direction spreading part having an inside passage part 522a near the inlet part, an outside passage part 522b near the flame holes, and an intermediate passage part 522c connecting the inside passage part with the outside passage part. According to the invention, in the gas burner, at least one portion in the radial direction of a lower surface of the inside passage part is positioned upward from a height of an uppermost portion of a lower surface of the outside passage part. In other words, with at least one part in the radial direction of a lower surface of the inside passage part, a part that is positioned upward from a height of a part that is positioned at the uppermost of a lower surface of the outside passage part is provided.

[0007] A second invention provides a heat-cooking apparatus that includes the aforementioned gas burner of the first invention.

[0008] According to the invention (a first invention), even if the boiling-over enters from each flame hole into the outside passage part of the radial-direction spreading part of the distribution passage, the boiling-over can be blocked at a high part of the lower surface of the inside passage part of the radial-direction spreading part. Accordingly, it can be suppressed that the boiling-over enters the inlet part of the distribution passage and the distribution chamber in the burner body. The boiling-over stays in a part near each flame hole, where it is easy to clean. As a result, it is possible to prevent deterioration of a combustion performance of the gas burner due to accumulation of the boiling-over in the distribution chamber in the burner body, which is difficult to clean.

[0009] In addition, in the invention, it is desirable that an entire lower surface of the inside passage part of the radial-direction spreading part in the distribution passage is positioned upward from a height of an upper edge of each flame hole. According to this, the penetration of the boiling-over from the inlet part of the distribution passage into the distribution chamber beyond the inside passage part can be suppressed more effectively.

[0010] Furthermore, in the invention, it is desirable that the burner head has an eave part 53 extending outward in the radial direction above each flame hole, and an annular first hanging wall part 531 extending downward is suspended at an outer circumferential part of a lower surface of the eave part. According to this, the boiling-over that dropped onto the burner head can be prevented from running through the outer circumferential part of the burner head and around to each flame hole. It should be noted that a height of a lower end of the first hanging wall part should be set upward from the upper edge of each flame hole so that a flame formed in each flame hole cannot come into contact with the first hanging wall part.

[0011] In this case, it is desirable that an annular second hanging wall part 532, which is positioned more inward in the radial direction than the first hanging wall part and extends downward, is suspended at the lower surface of the eave part. It should be noted that a height of a lower end of the second hanging wall part should be set higher than the height of the upper edge of each flame hole and should be set equal to or lower than that of the lower end of the first hanging wall part. According to this, the issue that running of the boiling-over around to each flame hole can be doubly suppressed by the first and second hanging wall parts. As a result, the effects of preventing the entry of the boiling-over into each flame hole can be improved.

[0012] Meanwhile, in a case where hydrogen, which has a faster combustion speed, is used as a fuel gas, it is necessary to assemble a backfire suppressing member 54 in the burner head to suppress backfire. However, if clogging occurs due to the penetration of the boiling-over into the backfire suppressing member, the gas will be difficult to be adequately distributed, resulting in ignition failure. In view of the foregoing, in the invention, in a case where the entire lower surface of the inside passage part of the radial-direction spreading part of the distribution passage is positioned more upward than the upper edge of each flame hole, and where the distribution passage has a vertical-direction passage part 523 that extends upward from the distribution chamber toward the inlet part, it is desirable that the backfire suppressing member, which is constituted by a porous body consisting of a metal or a ceramic, is interposed in the inside passage part or in the vertical-direction passage part, and is configured that the gas passed through the backfire suppressing member is distributed to each flame hole. According to this, the boiling-over can be suppressed to penetrate into a disposed part of the backfire suppressing member. Therefore, the backfire suppressing member is not clogged by the penetration of the boiling-over, and the ignition failure can be prevented.

[0013] Furthermore, in this case, the gas burner is configured that when the gas flowing from the gas inlet pipe is used as the fuel gas, which is not mixed with primary air, and the fuel gas is ejected from each flame hole and diffusely combusted, even though the fuel gas is hydrogen, it is possible to ensure a stable combustion performance.Brief Description of the Drawings

[0014] FIG. 1 is a perspective view of a major part of a heat-cooking apparatus including a gas burner of an embodiment of the invention. FIG. 2 is a cross-sectional view cut at II-II of FIG. 1. FIG. 3 is a perspective view showing a disassembled state of the gas burner in the embodiment. FIG. 4 is an enlarged cross-sectional view of a major of a gas burner in another embodiment. Description of Embodiments

[0015] FIGS. 1, 2 show a heat-cooking apparatus that includes a gas burner A of an embodiment of the invention. The heat-cooking apparatus A has a top plate 1 covering an upper surface of an apparatus body omitted to show. A trivet 2 having a plurality of trivet pawls 21 is placed on the top plate 1 to surround a burner opening 11 that is opened in the top plate 1 and makes the gas burner A faced. In addition, an ignition electrode Aa and a thermocouple Ab for detecting a flame are attached to the gas burner A.

[0016] The gas burner A includes a burner body 4 that stands up from a downstream end of the gas inlet pipe 3 that is disposed below the top plate 1 toward the burner opening 11 and is supported by a supporting frame 12 fixed to the apparatus body, and a burner head 5 placed on the burner body 4. An upstream end of the gas inlet pipe 3 is connected to a gas outlet part 31a of a casing 31 of a valve unit for fuel gas. A gas nozzle 32 ejecting the fuel gas is provided at a downstream end part, which communicates with the gas outlet part 31a, of the valve unit. Therefore, a gas flowing in the gas inlet pipe 3 becomes a fuel gas that is not mixed with primary air. Hydrogen is used as a fuel gas. It should be noted that "hydrogen" includes not only pure hydrogen but also mixtures containing small amounts of additives for odorization or the like.

[0017] From one portion around a lower part of the burner body 4, a port part 41 is protruded, in which a connecting opening 41a for a joint 33 that is provided at a downstream end of the gas inlet pipe 3 is formed. The burner body 4 has therein an annular distribution chamber 42 in which the gas (fuel gas) from the gas inlet pipe 3 flows. In addition, the burner head 5 has a plurality of flame holes 51, each of which opens in an outer circumferential surface of the burner head 5 and is provided at intervals in a circumferential direction 4, and a distribution passage 52 that distributes the fuel gas from the distribution chamber 42 to each of the flame holes 51. Then, the fuel gas ejects from each flame hole 51 and combusts diffusely.

[0018] With reference also to FIG. 3, a structure of the burner head 5 is described in more detail. The burner head 5 is constituted by two members arranged in a vertical direction, one of which a lower member 5L coming into contact with the burner body 4 and the other of which is an upper member 5U placed on the lower member 5L. These two members 5L, 5U are fastened with a short screw 5a at three portions in the circumferential direction to be assembled as a burner head 5. The assembled burner head 5 is fastened to the burner body 4 with a long screw 5b at three portions in the circumferential direction. Topology of three portions at which the long screw 5b is screwed is different from that of the three portions at which the short screw 5a is screwed. After fastening the burner head 5 to the burner body 4, a covering plate 6 is placed on the upper member 5U, and both the short screws 5a and the long screws 5b are concealed.

[0019] A distribution passage 52 has an inlet part 521 in which the gas from the distribution chamber 42 in the burner body 4 flows and which is positioned inward in a radial direction, and a radial-direction spreading part 522 that spreads in the radial direction from the inlet part 521 toward each flame hole 51. A tubular through-hole that communicates to the distribution chamber 42 and pierces vertically is formed in the lower member 5L, and a vertical-direction passage part 523 that extends upward from the distribution chamber 42 toward the inlet part 521 and is one of the constituent elements of the distribution passage 52 is constituted by the through-hole. It should be noted that at a plurality of portions in the circumferential direction at a lower part in the through-hole, connecting portions 523a that connect an outer circumferential wall and an inner circumferential wall of the through-hole are provided. In addition, the radial-direction spreading part 522 is defined between the lower member 5L and the upper member 5U. The radial-direction spreading part 522 has an inside passage part 522a near the inlet part 521, an outside passage part 522b near the flame holes 51, and an intermediate passage part 522c connecting the inside passage part 522a and the outside passage part 522b.

[0020] More specifically, an upper-surface part of the lower member 5L, which is positioned on an outer side in the radial direction from the inlet part 521, is formed into a stepped shape of which a part near the inlet part 521 of the upper-surface part is high and an outer circumferential part of the upper-surface part is lowered, and a plurality of stepped projection parts 5La, of which an outer side in the radial direction is lowered, is provided at the outer circumferential part of the upper-surface part at intervals in the circumferential direction. In addition, an annular wall 5Ua that comes into contact with upper surfaces of all the stepped projection parts 5La is suspended from the outer circumferential part of a lower surface of the upper member 5U. Then, it is configured that the inside passage part 522a is defined between a part near the inlet part 521of the upper-surface part of the lower member 5L on a more outer side in the radial direction than the inlet part 521 and the lower surface of the upper member 5U. Furthermore, the intermediate passage part 522c, the outside passage part 522b, and each flame hole 51 positioned at an outer end in the radial direction are constituted in a subsequence from an inner side in the radial direction by a clearance that is positioned between adjacent stepped projection parts 5La, 5La that are covered by the annular wall 5Ua. Here, an entire lower surface of the inside passage part 522a is positioned more upward from a height of an upper edge of each flame hole 51. Naturally, the entire lower-surface of the inside passage part 522a is positioned upward from a height of a part, which is positioned at an uppermost position, of a lower surface of the outside passage part 522b. It should be noted that in the embodiment, the outside passage part 522b is positioned horizontally. Therefore, the entire lower-surface of the outside passage part 522b is a part that is positioned at an uppermost position in the lower surface thereof. In addition, the intermediate passage part 522c is inclined downward from the inside passage part 522a to the outside passage part 522b.

[0021] According to the embodiment, even if the boiling-over enters from each flame hole 51 into outside passage part 522b of the radial-direction spreading part 522 of the distribution passage 52, the boiling-over is blocked on the outer side of the inside passage part 522a, of which the lower surface is positioned upward from the height of the lower surface of the outside passage part 522b. Accordingly, it can be suppressed that the boiling-over enters the inside passage part 522a, the inlet part 521 of the distribution passage 52, the vertical-direction passage part 523, and the distribution chamber 42 in the burner body 4. The boiling-over stays in the outside passage part 522b near the flame holes 51, where it is easy to clean. As a result, it is possible to prevent deterioration of a combustion performance of the gas burner A due to accumulation of the boiling-over in the vertical-direction passage part 523 of the distribution passage 52 and the distribution chamber 42 in the burner body 4, where it is difficult to clean.

[0022] In addition, in the embodiment, an eave part 53 extending outward in the radial direction above each flame hole 51 is provided with the burner head 5. Specifically, the eave part 53 is constituted by extending an outer circumferential part of the upper member 5U of the burner head 5 outward in the radial direction from each flame hole 51. Then, an annular first hanging wall part 531 extending downward is suspended at the outer circumferential part of a lower surface of the eave part 53. This allows the boiling-over to run down through an outer circumferential part of the burner head 5 and to drop from the lower end of the first hanging wall part 531. Therefore, it can be prevented the boing-over from running around to each flame hole 51.

[0023] Furthermore, an annular second hanging wall part 532 that is positioned more inward in the radial direction than the first hanging wall part 531 and extends downward is suspended at the lower surface of the eave part 53. According to this, running around to each flame hole 51 of the boiling-over can be doubly suppressed by the first hanging wall part 531 and the second hanging wall part 532. As a result, the effect of preventing the entry of the boiling-over into each flame hole 51can be improved. It should be noted that a height of a lower end of each of the first and second hanging wall parts 531, 532 is positioned upward from the height of the upper edge of each flame hole 51 so that a flame formed in each flame hole 51 does not come into contact with either of first and second hanging walls 531, 532. In addition, the height of the lower end of the second hanging wall part 532 is equal to or lower than the height of the lower end of the first hanging wall part 531.

[0024] Meanwhile, in the gas burner A of the embodiment, as aforementioned, since the fuel gas is caused to eject from each flame hole 51 and is combusted diffusely, even if the fuel gas is hydrogen, backfire toward an inside of the gas burner A during combustion can be suppressed. However, since the inner spaces of the distribution passage 52 and distribution chamber 42 that are not in use are replaced with air, if the fuel gas flows in the inner spaces from the gas inlet pipe 3 due to an ignition operation, an air-fuel mixture of the fuel gas with air is produced in the distribution passage 52 and distribution chamber 42, and there is feasibility that the backfire toward the inside of the gas burner A occurs. Therefore, the embodiment is configured that an annular backfire suppressing member 54 is interposed in the inside passage part 522a to distribute the gas passing through the backfire suppressing member 54 to each flame hole 51.

[0025] The backfire suppressing member 54 is constituted by a porous body consisting of a metal or a ceramic. Specifically, the backfire suppressing member 54 is constituted by the porous body with innumerable minute-clearances equal to or smaller than a fire-extinguishing distance, such as a sintered body by sintering a laminated body of metal fibers or metal beads, a knitted body by knitting metal fibers into a knitted shape, or a porous ceramic. In addition, a plurality of protruding parts 5Lb, each of which comes into contact with an inner circumferential surface of the backfire suppressing member 54 to position the backfire suppressing member 54, is provided with an inner circumferential part of the upper-surface part, which faces an inside passage part 522a, of the lower member 5L of the burner head 5 at intervals in the circumferential direction.

[0026] Here, if the boiling-over penetrates into the backfire suppressing member 54 and clogging occurs, the gas cannot be adequately distributed to each flame hole 51, resulting in ignition failure. However, in the embodiment, since the backfire suppressing member 54 is interposed in the inside passage part 522a of which the entire lower surface is positioned upward from the height of the upper edge of each flame hole 51, the boiling-over can be suppressed from entering a disposed part of the backfire suppressing member 54. Therefore, clogging of the backfire suppressing member 54 due to the penetration of the boiling-over does not occur, thus preventing the ignition failure.

[0027] Incidentally, for cleaning, the burner head 5 is sometimes removed from the burner body 4 by loosening the long screws 5b. After cleaning, a user may attempt the ignition operation in a state where the user forgets to reattach the burner head 5 to the burner body 4. In this case, there is an issue that the backfire passes through the distribution chamber 42 in the burner body 4 and the inside of the gas inlet pipe 3, reaches the gas nozzle 32, and causes the gas nozzle 32 to be damaged by burning.

[0028] Therefore, in the embodiment, a second backfire-suppressing member 43 having a ventilation part through which the gas passes is provided in the distribution chamber 42. According to this, even if the ignition operation is performed in the state where the burner head 5 is forgotten to attach to the burner body 4, the backfire is blocked by the second backfire-suppressing member 43. Accordingly, the backfire can be prevented from reaching the gas nozzle 32, thereby eliminating a risk of damage to the gas nozzle 32 due to burning. It should be noted that although the second backfire-suppressing member 43 may be made of a porous body like the aforementioned backfire suppressing member 54, in the embodiment, the second backfire-suppressing member 43 is constituted by a sheet-metal member having a plurality of small holes 431 to reduce cost. Each of the small holes 431 functions as the ventilation part, and a hole diameter is equal to or smaller than the fire-extinguishing distance (for example, 0.6mm).

[0029] Here, the distribution chamber 42 is constituted by a lower distribution chamber 421 into which the gas flows from the gas inlet pipe 3 and a wider upper distribution chamber 422 that is positioned above the lower distribution chamber 421. Then, the second backfire-suppressing member 43 is laid on a bottom surface of the upper distribution chamber 422 so that each small hole 431 is positioned at a just upper part of the lower distribution chamber 421, and, in this state, is fastened to the burner body 4 with a plurality of screws 432.

[0030] The embodiment of the invention is described referring to the figures in the above. However, the invention is not limited to the embodiment. For example, in the aforementioned embodiment, although the gas burner A is a burner of a diffusion combustion type, provided that the gas inlet pipe 3 is of a mixing-pipe type, the burner may be of a premixing type in which an air-fuel mixture of the fuel gas with air ejects from each flame hole 51. However, in a case where hydrogen is used as a fuel gas, it is desirable that the burner is of the diffusion combustion type in view of suppressing the backfire. In addition, in the aforementioned embodiment, although a backfire suppressing member 54 is interposed in the inside passage part 522a of the radial-direction spreading part 522 of the distribution passage 52, alternatively, it may be possible that, as shown in FIG. 4, the backfire suppressing member 54 is interposed in the vertical-direction passage part 523 of the distribution passage 52.

[0031] Furthermore, in the aforementioned embodiment, although the entire lower surface of the inside passage part 522a of the radial-direction spreading part 522 of the distribution passage 52 is positioned upward from the height of the upper edge of each flame hole 51, this is not essential. It is sufficient that at least a portion in the radial direction of the lower surface of the inside passage part 522a is positioned upward from the height of the portion positioned at the uppermost position of the lower surface of the outside passage part 522b. For example, as shown in FIG. 4, in a case where the inside passage part 522a and the outside passage part 522b are inclined upward so as to be directed outward in the radial direction, respectively, it is sufficient that an outer-side end part in the radial direction of the lower surface of the inside passage part 522a is positioned upward from the height of the outer-side end in the radial direction that is the part positioned at the upmost position in the lower surface of the outside passage part 522b. In addition, it may also be possible for an entire radial-direction spreading part 522 to be formed into a downwardly curved shape that is V-shaped. In this case, the entire the radial-direction spreading part 522 has the following structure: the intermediate passage part 522c is positioned at the lowest position; the outside passage part 522b has an inclined part that is inclined upwardly to the outside in the radial direction from the intermediate passage part 522c; and the inside passage part 522a has an inclined part that is upwardly inclined and extends toward the inner side in the radial direction from the intermediate passage part 522c to a position higher than the upper end of the inclined part of the outside passage part 522b.Explanation of symbols

[0032] AGas burner 3Gas inlet pipe 4Burner body 42Distribution chamber 5Burner head 51Flame hole 52Distribution passage 521Inlet part 522Radial-direction spreading part 522aInside passage part 522bOutside passage part 522cIntermediate passage part 523Vertical-direction passage part 53Eave part 531First hanging wall part 532Second hanging wall part 54Backfire suppressing member

Examples

Embodiment Construction

[0015]FIGS. 1, 2 show a heat-cooking apparatus that includes a gas burner A of an embodiment of the invention. The heat-cooking apparatus A has a top plate 1 covering an upper surface of an apparatus body omitted to show. A trivet 2 having a plurality of trivet pawls 21 is placed on the top plate 1 to surround a burner opening 11 that is opened in the top plate 1 and makes the gas burner A faced. In addition, an ignition electrode Aa and a thermocouple Ab for detecting a flame are attached to the gas burner A.

[0016]The gas burner A includes a burner body 4 that stands up from a downstream end of the gas inlet pipe 3 that is disposed below the top plate 1 toward the burner opening 11 and is supported by a supporting frame 12 fixed to the apparatus body, and a burner head 5 placed on the burner body 4. An upstream end of the gas inlet pipe 3 is connected to a gas outlet part 31a of a casing 31 of a valve unit for fuel gas. A gas nozzle 32 ejecting the fuel gas is provided at a downstr...

Claims

1. A gas burner (A), comprising, a burner body (4) standing up from a downstream end of a gas inlet pipe (3), the burner body having therein a distribution chamber (42) in which a gas flows from the gas inlet pipe; and a burner head (5) placed on the burner body, the burner head having a plurality of flame holes (51) that are opened in an outer circumferential surface of the burner head and provided at intervals in a circumferential direction, and a distribution passage (52) that distributes the gas from the distribution chamber to each of the flame holes, wherein the distribution passage has an inlet part (521) in which the gas flows from the distribution chamber and which is positioned inward in a radial direction, and a radial-direction spreading part (522) that spreads in the radial direction from the inlet part to each flame hole, and wherein the radial-direction spreading part has an inside passage part (522a) near the inlet part, an outside passage part (522b) near the flame holes, and an intermediate passage part (522c) connecting the inside passage part with the outside passage part, characterized in that at least one portion in the radial direction of a lower surface of the inside passage part (522a) is positioned upward from a height of an uppermost portion of a lower surface of the outside passage part (522b).

2. The gas burner as claimed in claim 1, wherein an entire lower surface of the inside passage part is positioned upward from a height of an upper edge of each flame hole.

3. The gas burner as claimed in claim 1 or 2, wherein the burner head has an eave part (53) extending outward in the radial direction above each flame hole, and an annular first hanging wall part (531) extending downward is suspended at an outer circumferential part of a lower surface of the eave part.

4. The gas burner as claimed in claim 3, wherein an annular second hanging wall part (532), which is positioned more inward in the radial direction than the first hanging wall part and extends downward, is suspended at the lower surface of the eave part, and a height of a lower end of the second hanging part is set higher than the height of the upper edge of each flame hole and is set equal to or lower than that of a lower end of the first hanging wall part.

5. The gas burner as claimed in claim 2, wherein a backfire suppressing member (54) that is constituted by a porous body consisting of a metal or a ceramic is interposed in the inside passage part and is configured that the gas passed through the backfire suppressing member is distributed to each flame hole.

6. The gas burner as claimed in claim 2, wherein the distribution passage has a vertical-direction passage part (523) that extends upward from the distribution chamber toward the inlet part, and wherein a backfire suppressing member (54) that is constituted by a porous body consisting of a metal or a ceramic is interposed in the vertical-direction passage part and is configured that the gas passed through the backfire suppressing member is distributed to each flame hole.

7. The gas burner as claimed in claim 5 or 6, wherein the gas burner is configured that the gas flowing from the gas inlet pipe is used as a fuel gas, which is not mixed with primary air, and that the fuel gas is ejected from each flame hole and is diffusely combusted.

8. A heat-cooking apparatus comprising the gas burner as claimed in any of claims 1 to 7.

Images