WO2022007287A1

WO2022007287A1 - Burner cap of burner

Info

Publication number: WO2022007287A1
Application number: PCT/CN2020/128563
Authority: WO
Inventors: 苏勇杰; 刘华荣; 陈相权; 潘叶江
Original assignee: 华帝股份有限公司
Priority date: 2020-07-06
Filing date: 2020-11-13
Publication date: 2022-01-13
Also published as: CN111964058A

Abstract

A burner cap of a burner, comprising a burner cap body (1) and a gas carding device (2). The burner cap body (1) is provided with a gas cavity (101) opened downward and multiple main fire holes (102); the main fire holes (102) are communicated with the gas cavity (101); the gas carding device (2) is provided in the gas cavity (101) or at the opening of the gas cavity (101); the gas carding device (2) comprises connecting portions (21) and carding portions (22); the carding portions (22) are provided with several flow guide sheets (23) distributed in the circumferential direction thereof; the flow guide sheets (23) are obliquely provided on a horizontal plane; a pore (201) is formed between two adjacent flow guide sheets (23). The device can reduce back fire and reduce noise, achieving an effect of carding gas.

Description

a burner cap

technical field

The invention relates to the technical field of cookers, in particular to a combing gas device for a gas cooker.

Background technique

The combustion system of a domestic gas stove is mainly composed of a burner head and a fire cover. The premixed gas passes through the gas channel of the burner head to reach the fire cover and burns through the combustion holes. Existing burners on the market have different gas speeds through the gas channel of the burner to reach the various positions of the fire cover, which will lead to inconsistent combustion flame states, affect the appearance, and even affect the combustion performance.

technical problem

In addition, the existing burners usually do not have a structural design to reduce backfire and noise, and are prone to backfire and flameout noise, which affects the user experience.

technical solutions

The present invention aims to solve one of the problems existing in the related art at least to a certain extent. To this end, the present invention proposes a burner fire cover, which can not only comb the gas, but also reduce backfire and noise, and improve the user experience. Use experience. According to a kind of burner fire cover provided above, it is realized by the following technical solutions:

A burner fire cover includes a fire cover body, the fire cover body is provided with a downwardly open gas cavity and a plurality of main fire holes, the main fire holes are communicated with the gas cavity, and the fire cover also includes a gas cavity for reducing backflow. A combing gas device for fire and noise reduction, the combing gas device is arranged inside or at the opening of the gas cavity, and the combing gas device is provided with a plurality of inclined pores, and the pores communicate with the interior of the gas cavity and the opening. external.

In some embodiments, the fire cover body and the gas cavity are annular structures; the combing gas device includes a connecting part and a combing part, and the connecting part is respectively connected with the inner ring wall and the outer ring of the gas cavity. The inner ring and the outer ring whose walls are abutted, the carding part is located between the inner ring and the outer ring; the aperture is arranged on the carding part.

In the first embodiment, the carding portion is provided with several guide fins distributed along the circumferential direction thereof, the guide fins are inclined on the horizontal plane, and a gap is formed between two adjacent guide fins. described pores.

In the second embodiment, the deflector is formed by partially punching and cutting the combing part and then folding it up or down, and the deflector is formed between each deflector and the combing part. porosity.

In some embodiments, the number of the guide vanes is 60-80, and all the guide vanes are evenly distributed along the circumferential direction of the carding portion.

In some embodiments, the angle β between the guide vane and the horizontal plane is 15°˜60°.

In some embodiments, the connecting portion is provided with a positioning structure, and a limiting structure corresponding to the positioning structure is provided on the inner ring wall and/or the inner ring wall of the gas cavity, and the limiting structure is the same as that of the positioning structure. The positioning structures are matched and clamped.

In a third embodiment, the carding portion is provided with a plurality of hollow protrusions with openings distributed along the circumference thereof, and the openings form the pores.

In some embodiments, the hollowed-out protrusions are integrally punched outward from a part of the combing portion, and the edges of the hollowed-out protrusions are cut and separated from the carding portion to form the opening.

In some embodiments, the protruding portion of the hollowed-out protrusion is an arc-shaped surface or a spherical surface that protrudes upward or downward.

In some embodiments, the number of the hollowed-out protrusions is 60-80, and all the hollowed-out protrusions are evenly distributed along the circumferential direction of the carding portion.

beneficial effect

Compared with the prior art, the present invention at least includes the following beneficial effects: the gas combing device of the present invention has a simple and ingenious structure, and on the one hand, achieves the effect of combing the gas and changing the flow direction of the gas, and changing the gas from the burner head to achieve the effect of The airflow path of the burner cover is conducive to the full and uniform mixing of gas and air, making the combustion more complete and improving the combustion conditions; on the other hand, it can reduce the probability of backfire, reduce the noise of flameout, and improve the user experience.

Description of drawings

Figure 1 is a schematic structural diagram of the first combing gas device installed in a fire cover in Embodiment 1 of the present invention;

Fig. 2 is a schematic exploded view of the structure of the first combing gas device and the fire cover in Embodiment 1 of the present invention;

3 is a top view of the first combing gas device in Embodiment 1 of the present invention;

4 is a cross-sectional view of the first combing gas device in Embodiment 1 of the present invention;

Fig. 5 is a schematic structural diagram of the second combing part of the combing gas device in Embodiment 2 of the present invention;

Fig. 6 is a schematic structural diagram of the third combing part of the combing gas device in Embodiment 3 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments may be combined with each other in the case of no conflict.

Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific details disclosed below. Example limitations.

In the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrally connected; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication between the two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

实施例Example 1 1

As shown in Figures 1-4, a burner fire cover includes a fire cover body 1. The fire cover body 1 is provided with a downwardly opening gas cavity 101 and a plurality of main fire holes 102. The main fire holes 102 communicate with the gas cavity 101. . Among them, it also includes a combing gas device 2 for reducing tempering and noise. The combing gas device 2 is arranged inside or at the opening of the gas cavity 101, and the combing gas device 2 is provided with a number of inclined pores 201 for gas to pass through, One end of the hole 201 is connected to the inside of the gas chamber 101, and the other end is connected to the outside of the gas chamber 101, so that the gas chamber 101 can communicate with the burner head through the hole 101. By setting the inclined hole 201, the fire cover is prevented to a certain extent. The gas outside the main body 1 is transmitted vertically downward from the gas cavity 101 to the inside of the burner head, so as to reduce the noise of tempering and flameout. In addition, when the gas is transmitted vertically upward from the burner head to the combing gas device 2, it is redistributed to achieve the effect of combing the gas, and when the gas flows through the pores 201, its flow direction will be bent, so that the flow path of the gas changes, Then it flows to the inside of the gas chamber 101 of the fire cover body 1, and finally flows out from the main fire hole 102 and burns.

It can be seen that the burner fire cover of the present embodiment has a simple and ingenious structure of the combing gas device 2 . On the one hand, it achieves the effect of combing the gas and changing the gas flow direction, and changes the gas flow path from the burner burner head to the fire cover body 1 . , which is conducive to the full and uniform mixing of the gas and the air, making the combustion more sufficient and improving the combustion conditions; on the other hand, in the event of a flameout, the combing gas device 2 can effectively prevent the gas from the outside of the fire cover body 1 from entering the burner head. Thereby, the purpose of reducing the probability of tempering and reducing the noise of flameout can be achieved, and the user experience can be improved.

Preferably, a plurality of pores 201 are arranged on the combing gas device 2 at uniform intervals along the circumferential direction, so that the combing gas device 2 can evenly distribute the gas, and at the same time, the flow rate of the combing gas reaching the main fire holes 102 is guaranteed to ensure the flow rate of each main fire hole 102. Consistent flow rate improves combustion conditions and flame stabilization.

As shown in Figures 2-4, specifically, the fire cover body 1 and the gas chamber 101 are annular structures, the combing gas device 2 includes a connecting portion 21 and a combing portion 22, and the connecting portion 21 is disposed in the gas chamber 101 and is an inner ring 211 and the outer ring 212, the inner ring 211 and the outer ring 212 are in contact with the inner ring wall and the outer ring wall of the gas chamber 101 respectively to prevent the gas from passing through the gap between the connecting part 21 and the ring wall of the gas chamber 101, and the connection is lifted. Air tightness between the part 21 and the ring wall of the gas chamber 101 . The combing part 22 is arranged between the inner ring 211 and the outer ring 212, and the inner and outer sides of the combing part 22 are connected to the inner ring 211 and the outer ring 212 respectively. The pores 201, through the connecting part 21, realize the connection of the combing parts 22, which makes the assembly and disassembly of the combing gas device 2 simpler and more convenient. When the gas chamber 101 is inside the gas chamber 101, the flow path of the gas is changed and extended under the restriction of the combing part 22, and at the same time, it is more difficult for the gas outside the fire cover body 1 to enter the inside of the burner head , so as to achieve the effect of reducing tempering and flameout noise.

In other embodiments, the combing gas device 2 can also be arranged at the opening of the gas chamber 101, that is, at the bottom of the fire cover body 1. During installation, the upper end surfaces of the inner ring 211 and the outer ring 212 abut the gas chamber respectively. The lower end face of the inner ring wall and the lower end face of the outer ring wall 101, the combing part 22 is arranged between the inner ring 211 and the outer ring 212, and the combing part 22 is provided with a hole 201 connecting the gas cavity 101 and the burner head.

Preferably, the carding portion 22 is provided with several guide fins 23 distributed along its circumferential direction, the guide fins 23 are inclined on the horizontal plane, and pores 201 are formed between two adjacent guide fins 221. In this embodiment, all the guide fins 23 and the pores 201 between two adjacent guide fins 221 together constitute the carding portion 22 . Therefore, the guide fins 221 are designed to be inclined on the horizontal plane, so that the guide fins 221 not only play a guiding role in the flow of gas, but also effectively prevent the gas from the outside of the fire cover body 1 from entering the interior of the burner head, thereby reducing The effect of tempering and flameout noise; on the other hand, any two adjacent baffles 23 form the opposite side walls of the same hole 201, so not only does it not need to open additional holes 201, it saves manufacturing processes, reduces manufacturing costs, and is conducive to improving the company's products competitiveness.

Preferably, the number of guide vanes 23 is 60-80, and all the guide vanes 23 are evenly distributed along the circumferential direction of the carding portion 22, so as to ensure that the carding portion 22 has a high porosity, and improve the unit air intake rate and the air flow rate. The gas combing effect is ensured, and the equidistant between two adjacent pores 201 is ensured, so that the gas flow rate of the outer fire cover body 1 is consistent, the uniform gas distribution effect is achieved, and the combustion working condition and flame stability are improved. In this embodiment, the inclination directions of all the guide vanes 23 are the same, so that the inclination directions of each hole 201 can be the same, so as to avoid the interference of the air flow out of the two adjacent holes 201, and achieve the mute effect.

Preferably, the inside and outside of the guide vane 23 are fixedly connected to the inner ring 211 and the outer ring 212 respectively, and the angle β between the guide vane 23 and the horizontal plane is 15°-60°, so that the The included angle β between the central axis and the horizontal plane is 15°-60°, which can effectively ensure the blocking effect of the deflector 23 and each hole 201, even if the gas outside the fire cover body 1 is more difficult to enter through the combing part 22 To the inside of the burner burner head, to avoid tempering and flameout noise; in addition, when the gas flows vertically upward from the burner burner head and flows through the combing part 22, the flow direction is bent under the limitation of the guide plate 23 and the pores 201, Therefore, the gas flows into the gas chamber 101 in a direction not perpendicular to the horizontal plane. More preferably, the angle β between the guide vane 23 and the horizontal plane is 30°˜50°.

In other embodiments, the number, inclination angle and shape of the baffles 23 can be adjusted according to the actual size of the fire cover body 11. The guide vanes 23 can also be designed to be rotatably connected to the connecting portion 21, and each guide vane 23 can be rotated around the radial direction of the connecting portion 21, so that the inclination angle of each guide vane 23 can be adjusted according to the actual situation. At the same time, it can reduce the assembly precision requirements of the guide vane 23, reduce assembly difficulty and cost, and improve production efficiency and product competitiveness.

As shown in Figure 3-4, specifically, the height of the inner ring 211 is greater than the height of the outer ring 212, the height of the outer ring 212 is smaller than the height of the carding part 22 or the guide vane 23 in the vertical direction, and the inner side wall of the outer ring 212 It is fixedly connected with the lower end of each guide vane 23, so that when the gas flows through the pores 201, it can flow out from the radial gap between the two adjacent guide vanes 23, which is not only beneficial to increase the distance between the pores 201 and the gas cavity 101 The contact area can also save the manufacturing materials of the outer ring 212 and reduce the manufacturing cost of the combing gas device 2 .

As shown in Figures 2-4, further, the connecting portion 21 is provided with a positioning structure 202, and a limiting structure 103 corresponding to the positioning structure 202 is provided on the inner ring wall and/or the inner ring wall of the gas chamber 101, and the The structure 103 cooperates with the positioning structure 202 and is clamped. Specifically, a positioning structure 202 is provided on the outer side wall of the outer ring 212 away from the inner ring 211 , and a positioning structure 202 is provided on the inner side wall of the inner ring 211 away from the outer ring 212 . The ring walls are provided with limit structures 103 , so that the limit structures 103 and the positioning structures 202 are matched and clamped, so that the combing gas device 2 can be installed inside the gas chamber 101 more stably and reliably.

In this embodiment, the positioning structure 202 is a positioning protrusion, four positioning protrusions are provided at circumferential intervals on the outer side wall of the outer ring 212 away from the inner ring 211 , and the inner side wall of the inner ring 211 away from the outer ring 212 is circumferentially spaced Four positioning protrusions are provided. In the same radial direction, the positioning protrusions located on the inner ring 211 and the positioning protrusions located on the outer ring 212 form a pair. The limiting structure 103 is a limiting groove. Correspondingly, four limiting grooves are respectively provided on the inner ring wall and the inner ring wall of the gas chamber 101, and the two limiting grooves form a pair in the same radial direction. Therefore, the connection between the combing gas device 2 and the gas chamber 101 is made more stable and reliable through the cooperation of the four pairs of positioning protrusions and the four pairs of limiting grooves.

In other embodiments, the setting positions of the positioning protrusions may be reversed with the setting positions of the limiting grooves, and the number of the positioning protrusions and the limiting grooves may also be adjusted according to the actual situation.

实施例Example 22

As shown in FIG. 5 , the difference between this embodiment and Embodiment 1 is that the structure of the combing part 22 of the combing gas device is different. Specifically, the combing part 22 is a combing plate with an annular structure. The combing plate is provided with a number of guide fins 23 distributed along its circumferential direction. The guide fins 23 are arranged obliquely on the horizontal plane. Pores 201 are formed between 221 . When the gas is transmitted vertically upward from the burner head to the combing part 22, its flow direction is bent under the limitation of the guide plate 23 and flows out from the pores 201, so as to achieve the effect of combing the gas and changing the flow direction of the gas, prolonging the combustion process of the gas. The burner head reaches the air flow path of the fire cover body, which is conducive to the full and uniform mixing of the gas and the air, making the combustion more sufficient and improving the combustion conditions. In addition, in the event of a flameout, the gas combing plate and the deflector 23 can effectively prevent the gas from the outside of the fire cover body from entering the interior of the burner head, so as to achieve the purpose of reducing the probability of tempering and the noise of flameout, and improving the user experience.

Preferably, the baffles 23 are formed by partially punching and cutting the air comb plate and then folded up or down, and a hole 201 is formed between each baffle plate 23 and the air comb plate. It can be seen that the structure of the carding portion 22 is simple, which not only facilitates the rapid processing and forming of the guide fins 23, but also saves the connection process between each guide fin 23 and the inner ring and the outer ring in Example 1, thereby improving production efficiency and reducing manufacturing cost.

In this embodiment, the number of the guide fins 23 is 60-80, and all the guide fins 23 are evenly spaced along the circumferential direction of the comb plate, and all the guide fins 23 are inclined clockwise or counterclockwise. It is arranged to prevent the mutual interference of the gas flowing out from the two adjacent pores 201, and at the same time, it can also achieve uniform gas distribution, ensure that the gas flow rate of the fire cover body is consistent, improve the combustion stability, and achieve the effect of stabilizing the flame and reducing the combustion noise. . Preferably, the angle between the air guide plate 23 and the air combing plate is 15°˜60°, so that the limiting effect of the air combing plate and the air guiding plate 23 makes it more difficult for the gas outside the fire cover to pass through the combing part 22 Enter into the furnace head to avoid tempering and reduce flameout noise; the gaps between the three edges of the deflector 23 and the comb gas plate constitute pores 201, which increases the unit gas outlet area and makes the gas distribution more uniform , to improve combustion sufficiency and flame stability.

It can be seen that, compared with Embodiment 1, the combing gas device of this embodiment has a simpler structure, which is more conducive to the rapid processing and forming of the combing part 22 of the combing gas device, and the assembly requirements of the combing part 22 are lower, which reduces the manufacturing difficulty and cost. , to further enhance the competitiveness of products.

In other embodiments, the combing gas device can also omit the connecting parts (ie the inner ring and the outer ring) as described in Embodiment 1. When the combing part 22 is installed inside the gas cavity of the fire cover body, the The inner and outer sides of the gas chamber respectively abut on the inner and outer ring walls of the gas chamber as described in Embodiment 1. At the same time, the inner and outer sides of the combing portion 22 are provided with positioning structures. The inner and outer ring walls of the gas chamber are correspondingly provided. There is a limit structure matched with the positioning structure and clamped. When the combing part 22 is installed at the bottom of the gas chamber of the fire cover body, the inner and outer sides of the top surface of the combing part 22 are in contact with the lower end surface of the inner ring wall and the lower end surface of the inner ring wall of the gas chamber respectively, and the combing part 22 is clamped in the Between the flame cover body and the burner head.

实施例Example 33

As shown in FIG. 6 , the difference between this embodiment and Embodiment 2 is that the structure of the combing part 22 of the combing gas device is different. Specifically, the combing part 22 is a combing plate with an annular structure. Several hollow protrusions 203 with openings 204 are arranged on the combing plate along its circumferential direction. The openings 204 form pores 201. A hollowed-out protrusion 203 with an opening 204 is arranged on it, so that when the gas is transmitted vertically upward from the burner and flows through the hollowed-out protrusion 203, the flow path of the gas is changed under the limitation of the hollowed-out protrusion 203 so that the gas flow is not perpendicular to the horizontal plane. The gas outlet flows into the gas cavity of the fire cover body; at the same time, when the gas outside the fire cover enters the gas cavity of the fire cover body, it is more difficult to enter the furnace head due to the blocking effect of the comb gas plate and the hollow protrusion 203. , so as to achieve the effect of reducing tempering and flameout noise.

Preferably, the hollow protrusions 203 are integrally stamped outward from a part of the air comb plate, and the edges of the hollow protrusions 203 are cut and separated from the air comb plate to form openings 204, which facilitates the rapid prototyping of the hollow protrusions 203 and the pores 201. More preferably, the convex portion of the hollow protrusion 203 is an arc-shaped surface or a spherical surface that protrudes upward or downward. In this embodiment, the convex part of the hollow protrusion 203 is a spherical surface that protrudes upwards, so that the gas flow direction is bent at a larger angle, and at the same time, it is more difficult for the gas outside the fire cover to enter the inside of the burner head, so as to lift the gas flow. blocking effect. The number of the hollow protrusions 203 is 60-80, and all the hollow protrusions 203 are evenly distributed along the circumferential direction of the air combing plate.

It can be seen that by designing the convex part of the hollow protrusion 203 as an arc surface or a spherical surface, the blocking effect of the hollow protrusion 203 is better, which is beneficial to further reduce the noise of tempering and flameout; The gas flow direction is changed from vertical upward to the circumferential direction of the combing plate, and flows out tangentially from the pores 201, so that the bending degree of the gas outlet direction is larger, and the gas outlet direction of the gas can be stabilized.

In other embodiments, the combing gas device can also omit the connecting parts (ie the inner ring and the outer ring). When the combing part 22 is installed inside the gas chamber of the fire cover body, the inner and outer sides of the combing part 22 abut respectively, such as: The inner and outer ring walls of the gas chamber described in Example 1, meanwhile, the inner and outer sides of the combing portion 22 are provided with positioning structures, and the inner ring wall and the inner ring wall of the gas chamber are correspondingly provided with clips matched with the positioning structures. connected limit structure. When the combing part 22 is installed at the bottom of the gas chamber of the fire cover body, the inner and outer sides of the top surface of the combing part 22 are in contact with the lower end surface of the inner ring wall and the lower end surface of the inner ring wall of the gas chamber respectively, and the combing part 22 is clamped in the Between the flame cover body and the burner head.

In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiment", etc. means that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in the present invention at least one embodiment or example of . In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the parent features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. Substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

A burner fire cover, comprising a fire cover body (1), the fire cover body (1) is provided with a downwardly opening gas cavity (101) and a plurality of main fire holes (102), the main fire holes (102) ) communicates with the gas chamber (101), and is characterized in that it further comprises a combing gas device (2) for reducing tempering and noise, and the combing gas device (2) is arranged in the gas chamber (101) The inside or opening of the gas combing device (2) is provided with a number of inclined pores (201), and the pores (201) communicate with the inside and the outside of the gas cavity (101).

2. A burner fire cover according to claim 1, characterized in that the fire cover body (1) and the gas chamber (101) are annular structures; the combing gas device (2) comprises a connecting part (21) ) and a combing part (22), the connecting part (21) is an inner ring (211) and an outer ring (212) respectively abutting against the inner ring wall and the outer ring wall of the gas chamber (101). The combing part (22) is located between the inner ring (211) and the outer ring (212); the pores (201) are arranged in the combing part (22).
A burner fire cover according to claim 2, characterized in that, the combing portion (22) is provided with a plurality of guide fins (23) distributed along its circumferential direction, and the guide fins (23) The holes ( 201 ) are formed between two adjacent flow guide sheets ( 221 ).
A burner cap according to claim 3, characterized in that, the deflector (23) is formed by partially punching and cutting the combing portion (22) and then folding up or down, and each The pores (201) are formed between each of the guide vanes (23) and the carding portion (22).
A burner fire cover according to claim 3 or 4, characterized in that, the number of the guide fins (23) is 60-80, and all the guide fins (23) are arranged along the carding The circumferential direction of the part (22) is evenly distributed.
A burner fire cover according to claim 3 or 4, characterized in that the angle β between the guide plate (23) and the horizontal plane is 15°-60°.
The burner cap according to claim 2, characterized in that, the connecting portion (21) is provided with a positioning structure (202), and the inner ring wall and/or the inner ring of the gas chamber (101) is provided with a positioning structure (202). The wall is provided with a limiting structure (103) corresponding to the positioning structure (202), and the limiting structure (103) is matched with the positioning structure (202) for a snap connection.
A burner cap according to claim 2, characterized in that, the combing portion (22) is provided with a plurality of hollow protrusions (203) with openings (204) distributed along the circumference thereof, and the openings (204) The pores (201) are formed.
A burner fire cover according to claim 8, characterized in that the hollow protrusions (203) are integrally stamped outward from a part of the combing portion (22), and the hollow protrusions (203) The edge of the carding portion (22) is cut and separated to form the opening (204).
A burner fire cover according to claim 8, characterized in that, the convex part of the hollow protrusion (203) is an arc-shaped surface or a spherical surface that protrudes upward or downward.
A burner fire cover according to claim 8, characterized in that, the number of the hollowed-out protrusions (203) is 60-80, and all the hollowed-out protrusions (203) are along the combing portion (203). 22) is evenly distributed in the circumferential direction.