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, and a burner head 5 placed on the burner body 4, the burner body 4 having a distribution chamber 42 inside, into which fuel 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 52a spaced therefrom in the peripheral direction for jetting fuel gas from the distribution chamber 42 to cause diffusion burning, capable of suppressing a deviation from the regulated maximum thermal power of actual maximum thermal power.SOLUTION: In the distribution chamber 42, a flow control plate 43 is provided having a plurality of ventilation holes 431 through which fuel gas flowing from the gas inflow pipe 3 passes to the burner head 5. The maximum thermal power of the gas burner is regulated by the total opening area of the ventilation holes 431.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas burner suitable for using hydrogen gas as fuel gas, which includes a burner body rising from the downstream end of a gas inlet pipe and a burner head placed on the burner body, and to a cooking appliance equipped with this gas burner. [Background technology]

[0002] Originally, this type of gas burner had a burner body with a distribution chamber inside, into which gas flows via a gas inlet pipe, and a burner head with an annular wall exposed on the outer periphery of the burner head, with a plurality of flame holes spaced apart in the circumferential direction to eject the gas from the distribution chamber. Furthermore, when hydrogen gas is used as the fuel gas, it is necessary to take measures against flashback because of the extremely fast combustion speed.

[0003] As a countermeasure against such flashbacks, 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 system, flashbacks can be prevented by making the gaps between the partition plates equal to or smaller than the quenching distance.

[0004] In the conventional gas burner described above, the maximum heating power of the gas burner is determined by the maximum amount of fuel gas injected from the gas nozzle located at the upstream end of the gas inlet pipe. However, the fuel gas injected from the gas nozzle experiences pressure loss before being ejected from the flame holes in the burner head. Pressure loss also occurs within the gas inlet pipe. Variations in pressure loss within the gas inlet pipe due to manufacturing tolerances of the gas inlet pipe can cause the actual maximum heating power to deviate from the specified maximum heating power, which corresponds to the maximum amount of fuel gas injected from the gas nozzle.

[0005] In the gas burner described in Patent Document 1, the gas flowing in from the gas inlet pipe is a mixture of fuel gas and primary air. However, when hydrogen gas is used as the fuel gas, it is desirable to prevent flashback by ejecting the fuel gas from the flame holes as fuel gas that is not mixed with primary air, as is well known. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-124271 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above, the present invention aims to provide a gas burner that employs a diffusion combustion method and that can minimize the deviation of the actual maximum heating power from the specified maximum heating power, as well as a heating cooker equipped with this gas burner. [Means for solving the problem]

[0008] 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 mounted on the burner body, wherein the burner body has a distribution chamber inside into which gas flows in through the gas inlet pipe, and the burner head has an annular wall exposed to the outer circumferential surface of the burner head, and this annular wall is provided with a plurality of flame holes spaced apart in the circumferential direction for ejecting gas from the distribution chamber, 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 for diffusion combustion, and the distribution chamber is provided with a flow rate adjustment plate having a plurality of vent holes through which the gas flowing in from the gas inlet pipe passes toward the burner head, and the maximum firepower of the gas burner is determined by the total opening area of ​​the vent holes. A second invention of the present application is a cooking device characterized by including the gas burner of the first invention.

[0009] According to the present invention (first invention), the maximum heating power is determined downstream of the gas inlet pipe without being affected by pressure loss in the gas inlet pipe. Therefore, pressure loss in the gas inlet pipe does not affect the deviation of the actual maximum heating power. Therefore, the deviation of the actual maximum heating power from the specified maximum heating power can be kept small.

[0010] In addition, in the present invention, the gas 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. It is preferable that the flow rate adjustment plate be installed on the upper distribution chamber bottom portion so that the vent hole is located above the lower distribution chamber communication port. This arrangement positions the flow rate adjustment plate directly below the burner head, thereby reducing pressure loss from the flow rate adjustment plate to the burner holes. Therefore, even if there is variation in pressure loss from the flow rate adjustment plate to the burner holes, the range of this variation is small, and the deviation of the actual maximum heating power from the specified maximum heating power can be minimized.

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

[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 flow rate adjusting plate. This will prevent thermal deformation of the flow rate adjusting plate due to heat conduction from the burner body to the plate. Therefore, there is no risk of a gap being created between the plate and the bottom of the upper distribution chamber due to thermal deformation of the plate, which would result in excessive maximum heating power.

[0013] In addition, when the flow rate adjusting plate is laid on the bottom surface of the upper distribution chamber, the lower distribution chamber communication port is opened annularly on the bottom surface of the upper distribution chamber, and the vent holes are arranged annularly concentric with the lower distribution chamber communication port, it is desirable to form the vent holes so that the passage resistance of the fuel gas in a predetermined circumferential range centered on the circumferential part of the flow rate adjusting plate that coincides with the gas inlet pipe is larger than the passage resistance of the fuel gas in the part of the flow rate adjusting plate outside this circumferential range. This suppresses an increase in the amount of gas passing through the above-mentioned predetermined circumferential range close to the gas inlet pipe of the flow rate adjusting plate, thereby making the flame power distribution in the circumferential direction of the burner head uniform.

[0014] In the present invention, the diameter of the vent hole is preferably set to be equal to or less than the quenching distance, so that even if a flashback occurs within the burner body, the flashback can be prevented from progressing upstream of the flow rate adjusting plate. [Brief explanation of the drawings]

[0015] [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

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Incidentally, 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.

[0025] 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.

[0026] 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.

[0027] However, if the maximum heating power of the gas burner A is determined by the maximum amount of fuel gas injected from the gas nozzle 32, as described above, variations in pressure loss in the gas inlet pipe 3 due to manufacturing tolerances of the gas inlet pipe 3 may cause the actual maximum heating power to deviate from the specified maximum heating power corresponding to the maximum amount of fuel gas injected from the gas nozzle 32. To address this issue, in this embodiment, a flow rate adjusting plate 43 having a plurality of vent holes 431 through which gas flowing in from the gas inlet pipe 3 passes toward the burner head 5 is provided in the distribution chamber 42 in the burner body 4. The maximum heating power of the gas burner A is determined by the total opening area of ​​the vent holes 431. In other words, once the gas pressure upstream of the flow rate adjusting plate 43 increases to a predetermined pressure and the amount of gas passing through the flow rate adjusting plate 43 reaches an amount equivalent to the maximum heating power, the amount of gas passing through the flow rate adjusting plate 43 will no longer increase even if the gas pressure upstream of the flow rate adjusting plate 43 further increases from the predetermined pressure.

[0028] According to this, the maximum heating power is determined downstream of the gas inflow pipe 3 without being affected by pressure loss in the gas inflow pipe 3. Therefore, the pressure loss in the gas inflow pipe 3 does not affect the deviation of the actual maximum heating power. Therefore, the deviation of the actual maximum heating power from the specified maximum heating power can be kept small.

[0029] 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 in which a lower distribution chamber communication port 4221a communicating with the lower distribution chamber 421 is opened, 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 flow rate adjustment plate 43 is laid on the upper distribution chamber bottom 4221 so that the vent hole 431 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.

[0030] This means that the flow rate adjusting plate 43 is disposed directly below the burner head 5, reducing the pressure loss between the flow rate adjusting plate 43 and the burner holes 52. Therefore, even if there is variation in the pressure loss between the flow rate adjusting plate 43 and the burner holes 52, the range of this variation is small, and the deviation of the actual maximum heating power from the specified maximum heating power can be kept small.

[0031] In this embodiment, a positioning means 44 is further provided to position the flow rate adjustment plate 43 relative to the upper distribution chamber 422. The positioning means 44 is composed of notches 441 formed at two locations around the inner peripheral edge of the flow rate adjustment plate 43 and protrusions 442 protruding from two locations around the outer peripheral surface of the upper distribution chamber peripheral wall portion 4223. The notches 441 are engaged with the protrusions 442, thereby positioning the flow rate adjustment plate 43 relative to the upper distribution chamber 42. By positioning the flow rate adjustment plate 43 in this manner, the vent hole 431 does not deviate from a position above the lower distribution chamber communication port 4221a, and gas can reliably flow from the lower distribution chamber 421 to the upper distribution chamber 422 through the vent hole 431.

[0032] Furthermore, in this embodiment, 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 surface 4221 and the flow rate adjusting plate 43. This makes it possible to suppress heat conduction from the burner body 4 to the flow rate adjusting plate 43 by the heat insulating material 45, thereby preventing thermal deformation of the flow rate adjusting plate 43. Therefore, thermal deformation of the second flashback suppression member 54 does not create a gap between the upper distribution chamber bottom surface 4221 and the second flashback suppression member 54, preventing the maximum heating power from becoming excessive.

[0033] 5, the lower distribution chamber communication port 4221a is formed in an annular shape in the upper distribution chamber bottom portion 4221, and the vent holes 431 are arranged in an annular shape concentric with the lower distribution chamber communication port 4221a. The vent holes 431 are formed so that the gas passage resistance in a predetermined circumferential range 43a centered on the circumferential portion of the flow rate adjusting plate 43 that coincides with the gas inlet pipe 3, i.e., the connection port 41a, is greater than the gas passage resistance in a portion of the flow rate adjusting plate 43 outside this circumferential range 43a. Specifically, although not explicitly shown in the drawings, the diameter of the vent holes 431 in the predetermined circumferential range 43a is made smaller than the vent holes 431 outside this circumferential range 43a, or the arrangement pitch of the vent holes 431 in the predetermined circumferential range 43a is made wider than the arrangement pitch of the vent holes 431 outside this circumferential range 43a, so that the gas passage resistance in the predetermined circumferential range 43a is greater.

[0034] Gas from the gas inlet pipe 3 tends to flow more in a predetermined circumferential range 43a, which is a portion of the flow rate adjusting plate 43 close to the gas inlet pipe 3. However, by increasing the gas passage resistance in the predetermined circumferential range 43a, the increase in the amount of gas passing through this circumferential range 43a is suppressed, and the thermal power distribution in the circumferential direction of the burner head 5 can be made uniform.

[0035] 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.

[0036] Therefore, the diameter of the vent holes 431 of the flow rate adjusting plate 43 is set to, for example, 0.6 mm, which is less than the quenching distance. With this, even if the ignition operation is performed while the burner head 5 is not attached to the burner body 4, flashback is blocked by the flow rate adjusting plate 43, preventing flashback up to the gas nozzle 32 and eliminating the risk of the gas nozzle 32 being burned.

[0037] Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to this and can be implemented with various modifications within the scope of the invention. [Explanation of symbols]

[0038] 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 peripheral wall of upper distribution chamber, 4223...inner peripheral wall of upper distribution chamber, 43...flow rate adjustment plate, 431...vent, 44...positioning means, 45...insulation 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 inside into which gas flows in via the gas inlet pipe, and the burner head has an annular wall exposed to the outer circumferential surface of the burner head, and this annular wall has a plurality of flame holes spaced apart in the circumferential direction for ejecting gas from the distribution chamber, and 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, A gas burner characterized in that a flow rate adjusting plate having a plurality of vent holes through which gas flowing in from the gas inlet pipe passes toward the burner head is provided in the distribution chamber, and the maximum firepower of the gas burner is determined by the total opening area of ​​the vent holes.

2. The gas burner according to claim 1, characterized in that the gas 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, and the upper distribution chamber is surrounded by an annular upper distribution chamber bottom surface 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 surface portion, and an upper distribution chamber inner wall portion erected on the inner periphery of the upper distribution chamber bottom surface portion, and the flow rate adjustment plate is laid on the bottom surface of the upper distribution chamber so that the air hole is located above the lower distribution chamber communication port.

3. 3. A gas burner according to claim 2, further comprising positioning means for positioning said flow rate adjusting plate relative to said upper distribution chamber.

4. 3. The gas burner according to claim 2, 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 flow rate adjusting plate.

5. 3. A gas burner according to claim 2, wherein the lower distribution chamber communication port is opened in an annular shape on the bottom surface of the upper distribution chamber, and the air vents are arranged in an annular shape concentric with the lower distribution chamber communication port, and the air vents are formed so that the gas passage resistance in a predetermined circumferential range centered on the circumferential part of the flow rate adjusting plate that coincides with the gas inlet pipe is greater than the gas passage resistance in the part of the flow rate adjusting plate outside this circumferential range.

6. 2. The gas burner according to claim 1, wherein the diameter of said vent hole is set to be equal to or smaller than the quenching distance.

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

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