CN113494709A

CN113494709A - Heat shield for stove and gas stove with same

Info

Publication number: CN113494709A
Application number: CN202010203789.6A
Authority: CN
Inventors: 郭达; 李林; 俞瑜; 郑军妹
Original assignee: Ningbo Fotile Kitchen Ware Co Ltd
Current assignee: Ningbo Fotile Kitchen Ware Co Ltd
Priority date: 2020-03-20
Filing date: 2020-03-20
Publication date: 2021-10-12
Anticipated expiration: 2040-03-20
Also published as: CN113494709B

Abstract

The invention relates to a heat shield for a stove and a gas stove applying the heat shield, which are characterized in that: including the annular cover body, the central authorities of the cover body form annular chamber, its characterized in that: the cover body is also provided with a lower layer cover, a preheating cavity is formed between the lower layer cover and the cover body, an air supplementing opening for communicating the annular cavity and the preheating cavity is locally arranged on the inner side wall of the lower layer cover, and an air inlet part for allowing external air to flow into the preheating cavity is arranged on the outer side wall or the bottom wall of the cover body.

Description

Heat shield for stove and gas stove with same

Technical Field

The invention relates to the technical field of household kitchen utensils, in particular to a heat shield with good heat insulation effect for a stove and a gas stove with the heat shield.

Background

In the actual use process of the existing gas stove, because a pot is placed on a pot support for heating, and a certain space interval is formed between the pot and a burner, the heat energy generated by gas combustion is used for heating the pot, and a considerable part of the heat energy is dissipated to the surrounding environment, so that energy waste is caused; in order to solve the above problems, in recent years, there have been some heat collecting and energy concentrating covers in China, such as "the energy concentrating ring for the gas stove and the gas stove with the same" disclosed in chinese patent CN203404823U, the energy concentrating ring is an energy saving component surrounding the periphery of the burner, for the gas stove with the energy concentrating ring, the lateral secondary air supplied to the burner is further affected due to the blocking of the energy concentrating ring, in addition, the gas stove with the energy concentrating ring is applied, the secondary air supplementary channel is the lateral air intake, although the secondary air can be preheated when flowing through the secondary air supplementary channel of the energy concentrating ring, the preheating effect of the secondary air is not good due to the small preheating surface, so the applicant provides a heat insulating cover for the gas stove of chinese invention patent No. ZL 201821338317.6(CN209459017U) and discloses a heat insulating cover for the gas stove with the heat insulating cover, this kitchen is with heat exchanger that separates is including the annular cover body, the central authorities of the cover body are formed with the annular chamber, the cover body is double-deck and has cavity, its characterized in that: the cover body is formed the intercommunication has been seted up along circumference interval on the inside wall of annular chamber the annular chamber with the venthole of cavity, the cover body then has seted up on lateral wall or diapire and has supplied the inflow of outside air the inlet port of cavity, in order to ensure that the side direction secondary air that the heat exchanger provides for the combustor is smooth and easy and the capacity for the kitchen, the inlet port is connected with outside air feed portion, and this air feed portion can be the air-blower preferentially.

The above patent applications disclose that the secondary air is effectively preheated for sufficient combustion, but in addition to the secondary air, the gas range burner needs to supplement the primary air when injecting the gas for sufficient combustion, and also needs to further improve the existing heat shield for the range in order to preheat the primary air.

Disclosure of Invention

A first technical problem to be solved by the present invention is to provide a heat shield for a range, which can supply preheated primary air to a burner, in view of the above-mentioned prior art.

The second technical problem to be solved by the present invention is to provide a gas stove using the heat insulation cover for stove in view of the above prior art.

The technical scheme adopted by the invention for solving the first technical problem is as follows: this kitchen is with heat exchanger that separates, including the annular cover body, the central authorities of the cover body form annular chamber, its characterized in that: the cover body is also provided with a lower layer cover, the lower layer cover and the cover body are provided with a preheating cavity, the inner side wall of the annular cavity of the lower layer cover is locally provided with an air supplementing opening for communicating the annular cavity with the preheating cavity, and the outer side wall or the bottom wall of the cover body is provided with an air inlet part for external air to flow into the preheating cavity.

In order to enable the air flowing out of the air supply opening to be preheated air, at least one partition is preferably arranged in the lower layer cover, and the partition can separate the air supply opening and the preheating cavity into two relatively independent spaces.

The structure of separator can have the multiple, from simple structure's angle, preferably, the separator is including two blocks of curb plates that vertical interval set up, have between two blocks of curb plates and communicate preheat the cavity with the clearance in moisturizing mouth. The preheating cavity and the air supplementing port are separated by the aid of the two side plates, the preheating cavity is a relatively closed cavity, air can be preheated better, air driving the preheating cavity can be preheated under the injection effect of the injection pipe of the combustor and then flows out to the air supplementing port through gaps, and the preheated air enters the corresponding injection pipe as primary air and fuel gas together when being injected.

In order to better realize that the air driving the preheating cavity can flow out to the air supply opening through the gap faster after being preheated under the injection action of the injection pipe of the combustor, preferably, the air supply opening is more sunken than the preheating cavity, and the air supply opening is adjacent to the gap and is provided with a flow guide slope gradually inclining towards the air supply opening from top to bottom.

In order to better preheat the air entering the preheating cavity through the air inlet part, the bottom wall of the lower layer cover preferably comprises a first bottom wall corresponding to the preheating cavity, and the upper surface of the first bottom wall is provided with first preheating grooves arranged at intervals in the radial direction and second preheating grooves arranged at intervals in the circumferential direction.

In order to better realize better energy gathering effect, preferably, the cover body is of a double-layer structure and comprises an upper layer cover and a middle layer cover, an annular seam is formed between the lower layer cover and the middle layer cover and forms the air inlet part, and the lower layer cover is circumferentially spaced from at least two connecting ribs extending towards the middle layer cover. The lower layer cover and the middle layer cover are connected in a point contact mode through the connecting ribs, so that the phenomenon that the gas stove panel is overheated due to the fact that the combustion heat of the cover body generated in the combustion process of the combustor is conducted downwards to the lower layer cover and then conducted to the gas stove panel can be avoided.

In order to better support the pot, the upper surface of the upper layer cover is preferably provided with pot supporting feet along the circumferential direction.

To solve the second technical problem, preferably, the present invention provides a gas cooker with the heat shield for cookers, including a gas cooker panel and a burner, where the burner includes:

a base;

the inner ring fire cover is arranged above the base, and an inner ring gas mixing chamber is formed between the inner ring fire cover and the base;

the inner injection pipe comprises an air inlet end and an air outlet end, and the air outlet end of the inner injection pipe is communicated with the inner ring air mixing chamber;

the method is characterized in that:

the annular cavity of the heat shield surrounds the combustor and is placed on a gas stove panel, and the air supply opening of the shield body is aligned with the air outlet end of the inner injection pipe.

In order to better realize the fire outlet uniformity of the outer ring fire cover, the outer ring fire cover further comprises an outer ring fire cover and an outer injection pipe, the outer ring fire cover is also arranged on the base, an outer ring gas mixing chamber is formed between the outer ring fire cover and the base, the outer ring gas mixing chamber comprises an inner ring wall, an outer ring wall and a bottom ring wall which is connected with the inner ring wall and the outer ring wall, the bottom ring wall is provided with at least one lower notch, the gas outlet end of the outer injection pipe is communicated with the lower notch, and the lower notch is covered with a flow equalizing plate. The arrangement of the uniform flow plate can enhance that the fuel gas flowing out through the outer injection pipe flows into the outer ring gas mixing chamber more uniformly.

In order to enhance the injection capability of the burner and improve the combustion efficiency, the number of the outer injectors is two, preferably, the lower recess has a partition part, the partition part divides the lower recess of the bottom ring wall into a first lower recess and a second lower recess, the first lower recess has a first slope part inclined towards the partition part, the second lower recess has a second slope part inclined towards the partition part, correspondingly, the outer injector comprises a first outer injector with an air outlet end communicated with the first lower recess and a second outer injector with an air outlet end communicated with the second lower recess.

In order to realize the combustion efficiency of the outer ring fire cover, preferably, a first flow distributing plate covers the first lower notch, the first flow distributing plate includes a first closed portion corresponding to the first slope portion and a first open portion corresponding to the first lower notch except the first closed portion, the first open portion has at least two first through holes, and the first closed portion gradually inclines upward from the partition portion to the first open portion. The first closing part serves to guide the mixture of the gas and the primary air, which is discharged from the first outer injector, into the first opening part more quickly, and since the first opening part has at least two through holes, the gas and the primary air can flow more uniformly to the outer ring gas mixing chamber due to the first opening part.

Similarly, the second lower recess is covered with a second flow equalizing plate, the second flow equalizing plate comprises a second closed portion corresponding to the second slope portion and a second open portion corresponding to the second closed portion at the second lower recess, the second open portion comprises at least two second through holes, and the second closed portion gradually inclines upwards from the separating portion to the second open portion. The second closed portion serves to guide the mixture of the fuel gas and the primary air, which is discharged from the second outer injector, into the second open portion more quickly, and since the second open portion has at least two through holes, the fuel gas and the primary air can flow more uniformly toward the outer ring gas mixing chamber due to the second open portion.

Compared with the prior art, the gas stove has the advantages that air flowing in from the air inlet part of the heat shield for the stove enters the preheating cavity of the heat shield and can be effectively preheated, the preheated air can flow out of the air supplementing port under the injection effect of the burner and then enters the injection pipe of the burner to provide preheated primary air, and further the utilization rate of gas is effectively improved.

Drawings

FIG. 1 is a schematic view of a heat shield for a cooking range according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is a schematic view of a lower mask according to an embodiment of the present invention;

FIG. 4 is a schematic view of a burner according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view of FIG. 4;

FIG. 6 is an exploded view of FIG. 4;

FIG. 7 is a schematic structural diagram of an outer ring air mixing chamber according to an embodiment of the present invention;

FIG. 8 is a schematic structural view of a first flow distributing plate according to an embodiment of the present invention;

fig. 9 is a schematic structural view of a second flow equalizing plate according to an embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

As shown in FIGS. 1 to 9, the preferred embodiment of the present invention is shown. The stove of this embodiment is with separating heat exchanger is including annular cover body 1, the central authorities of the cover body 1 are formed with annular chamber 11, the cover body 1 still has lower floor's cover 12, lower floor's cover 12 is formed with preheating cavity 13 with the cover body 1, lower floor's cover 12 is provided with the air supplement mouth 14 that feeds through annular chamber 11 and preheating cavity 13 on the inside wall that forms annular chamber 11 partially, cover body 1 then sets up the inlet portion 15 that supplies the external air to flow into preheating cavity 13 on lateral wall or diapire, the air that flows in from the inlet portion 15 of stove with separating heat exchanger gets into and can be effectively preheated in preheating cavity 13 of separating heat exchanger, the air after preheating can be flowed out the air supplement mouth by combustor 4's injection effect down, thereby get into in combustor 4's the injection pipe in order to provide the primary air after preheating, and then improve gas utilization ratio effectively.

In particular, in order to make the air flowing out from the air supply opening 14 be preheated air, at least one partition 2 is arranged in the lower layer cover 12, the partition 2 can separate the air supply opening 14 and the preheating cavity 13 into two relatively independent spaces, wherein the structure of the separating element 2 can be various, and from the viewpoint of simple structure, preferably, the separating element 2 comprises two side plates which are vertically arranged at intervals, a gap 21 which is communicated with the preheating cavity 13 and the air supply opening 14 is arranged between the two side plates, the preheating cavity 13 and the air supply opening 14 can be separated by the two side plates, the preheating cavity 13 is a relatively closed cavity, so that air can be preheated better, the air driving the preheating cavity 13 can be preheated under the injection effect of the injection pipe of the combustor 4 and then flows out to the air supply opening 14 through the gap 21, and the preheated air enters together with fuel gas as primary air when being injected into the corresponding injection pipe. In addition, in order to better realize that the air driving the preheating cavity 13 can flow out to the air supply opening 14 through the gap 21 faster after being preheated under the injection effect of the injection pipe of the combustor 4, and the air supply opening 14 sinks more than the preheating cavity 13, the air supply opening 14 is provided with a flow guiding slope 141 gradually inclining towards the air supply opening 14 from top to bottom adjacent to the gap 21. Wherein the bottom wall of the lower shield 12 includes a first bottom wall 121 corresponding to the preheating cavity 13, the upper surface of the first bottom wall 121 has first preheating grooves 1211 arranged at intervals along the radial direction and second preheating grooves 1212 arranged at intervals along the circumferential direction, and the first preheating grooves 1211 and the second preheating grooves 1212 are arranged in a crossed manner to enable the air to stay in the preheating cavity 13 for a longer time, so that the preheating efficiency is higher. In order to better realize a better energy gathering effect, the cover body 1 in the embodiment has a double-layer structure and comprises an upper layer cover 101 and a middle layer cover 102, an annular seam 103 is formed between the lower layer cover 12 and the middle layer cover 102, the annular seam 103 forms an air inlet part 15, at least two connecting ribs 104 are formed on the lower layer cover 12 and extend towards the middle layer cover 102 at intervals along the circumferential direction, the lower layer cover 12 and the middle layer cover 102 are connected in a point contact mode through the connecting ribs 104, and therefore the phenomenon that the gas stove panel is overheated due to the fact that combustion heat generated by the cover body 1 in the combustion process of the combustor 4 is conducted downwards to the lower layer cover 12 and then conducted to the gas stove panel is avoided. Finally, in order to better support the pot, the upper surface of the upper cover 101 is provided with pot feet 1011 along the circumferential direction.

In addition, the gas range includes the gas range panel (not shown in the figure) and burner 4, the burner 4 includes the base 41, set up above the base 41, and form inner ring fire lid 42 and inner injection pipe 44 of the gas mixing chamber 43 with the base 41, the inner injection pipe 44 includes leading-in end 441 and leading-out end 442, the leading-out end 442 of the inner injection pipe 44 is communicated with inner ring gas mixing chamber 43, and the annular chamber 11 of the heat shield surrounds the burner 4 and rests on the gas range panel, the air supplement port 14 of the cover body 1 is aligned with leading-out end 442 of the inner injection pipe 44 and set up, the gas range can utilize the preheated air that the heat shield setting up on the panel of cooking utensils outflows to be injected together with gas by the injection pipe, thus has raised the gas combustion efficiency effectively. In order to better realize the fire outlet uniformity of the outer ring fire cover 45, the fire outlet device further comprises an outer ring fire cover 45 and an outer injection pipe 46, the outer ring fire cover 45 is also arranged on the base 41, an outer ring air mixing chamber 47 is formed between the outer ring fire cover 45 and the base 41, the outer ring air mixing chamber 47 comprises an inner ring wall 471, an outer ring wall 472 and a bottom ring wall 473 connecting the inner ring wall 471 and the outer ring wall 472, the bottom ring wall 473 is provided with at least one lower notch 4731, the air outlet end 461 of the outer injection pipe 46 is communicated with the lower notch 4731, the lower notch 4731 is covered with a flow equalizing plate 5, and the arrangement of the flow equalizing plate 5 can enhance that the gas flowing out through the outer injection pipe 46 flows into the outer ring air mixing chamber 47 more uniformly. In order to enhance the injecting capability of the burner 4 and improve the combustion efficiency, the number of the outer injectors is two, and for this purpose, preferably, the lower recess 4731 has a partition portion 4731b, the partition portion 4731b divides the lower recess 4731 of the bottom ring wall 473 into a first lower recess 4732 and a second lower recess 4733, the first lower recess 4732 has a first slope portion 4732a inclined toward the partition portion 4731b, the second lower recess 4733 has a second slope portion 4733a inclined toward the partition portion 4731b, and correspondingly, the outer injector includes a first outer injector 6 having an air outlet end 461 communicating with the first lower recess 4732 and a second outer injector 70 having an air outlet end 461 communicating with the second lower recess 4733. In order to realize the combustion efficiency of the outer ring fire cover 45, the first lower notch 4732 is covered with a first flow distributing plate 5, the first flow distributing plate 5 includes a first closed portion 5a corresponding to the first slope portion 4732a and a first open portion 5b corresponding to the first lower notch 4732 except the first closed portion 5a, the first open portion 5b has at least two first through holes 51b, and the first closed portion 5a is gradually inclined upward from the partition portion 4731b toward the first open portion 5b, the first closed portion 5a serves to guide the mixture of the gas and the primary air injected from the first outer injector 6 into the first open portion 5b more quickly, and the gas and the primary air can more uniformly flow toward the outer ring gas mixing chamber 47 due to the first open portion 5b having at least two through holes. Similarly, the second lower notch 4733 is covered with a second flow distribution plate 7, the second flow distribution plate 7 includes a second closed portion 7a corresponding to the second slope 4733a and a second open portion 7b corresponding to the second lower notch 4733 except for the second closed portion 7a, the second open portion 7b has at least two second through holes 71b, and the second closed portion 7a is gradually inclined upward from the partition portion 4731b toward the second open portion 7b, the second closed portion 7a serves to guide the mixture of the gas and the primary air, which is extracted from the second outer injector 70, into the second open portion 7b more quickly, and since the second open portion 7b has at least two through holes, the gas and the primary air can more uniformly flow toward the outer ring gas mixing chamber 47 due to the second open portion 7 b.

The heat shield is a three-layer shield formed by a two-layer structure shield body 1 formed by an upper layer shield 101 and a middle layer shield 102 and a lower layer shield 12 together, wherein the heat storage material is arranged in the shield body 1 formed by the upper layer shield 101 and the middle layer shield 102 to achieve better energy gathering effect, an annular seam 103 forming an air inlet part 15 is formed between the lower layer shield 12 and the middle layer shield 102, at least two connecting ribs 104 extending towards the middle layer shield 102 along the circumferential direction of the lower layer shield 12 at intervals are connected with the lower layer shield 12 and the middle layer shield 102 in a point contact mode through the connecting ribs 104, so that the phenomenon that combustion heat generated by the shield body 1 in the combustion process of a combustor 4 is downwards conducted to the lower layer shield 12 and then conducted to a gas stove panel to cause gas stove panel overheating can be avoided, the heat shield further comprises a preheating cavity 13 and an air supplement opening 14 which are in fluid communication through a gap 21, when the heat shield is placed on the gas stove panel by surrounding the burner 4 through the annular cavity 11, the air supply port of the heat shield sinks more than the preheating cavity 13, and the air supply port 14 of the heat shield is aligned with the air outlet port 442 of the inner injection pipe 44, the gas stove can utilize the preheated primary air flowing out of the heat shield arranged on the stove panel to be injected together with the gas by the injection pipe, so as to effectively improve the combustion efficiency of the gas, finally, in order to improve the combustion efficiency of the outer ring fire cover 45, the outer ring fire cover 45 of the embodiment is the infrared burner 4, wherein in order to enhance the injection capability of the burner 4 and improve the combustion efficiency, the outer injector and the outer injection pipe 46 corresponding to the infrared burner 4 are divided into two, namely a first outer injection pipe 46a and a second outer injection pipe 46b, for this reason, the outer ring fire cover 45 is used for improving the mixing of the primary air in the outer ring gas mixing chamber 47, the outer ring air mixing chamber 47 is provided with a lower notch 4731 directly connected with the air outlet end 461 of the outer injection pipe 46 and is provided with a separating part 4731b, the separating part 4731b separates the lower notch 4731 of the bottom ring wall 473 into a first lower notch 4732 and a second lower notch 4733, and the gas and the primary air flowing out of the first outer injection pipe 46a and the second outer injection pipe 46b respectively flow around the outer ring air mixing chamber 47 in the clockwise direction and the anticlockwise direction under the action of the first lower notch 4732 and the second lower notch 4733, and the gas and the primary air are finally mixed better in the outer ring air mixing chamber 47 under the action of the first flow equalizing plate 5 and the second flow equalizing plate 7.

Claims

1. A heat shield for a cooking stove comprises an annular shield body (1), wherein an annular cavity (11) is formed in the center of the shield body (1), and the heat shield is characterized in that: the cover body (1) still has lower floor's cover (12), lower floor cover (12) with the cover body (1) is formed with preheats cavity (13), lower floor cover (12) are forming the intercommunication has been seted up locally on the inside wall of annular chamber (11) with mend wind gap (14) of preheating cavity (13), cover body (1) then set up on lateral wall or diapire and supply the outside air to flow in preheat air inlet portion (15) of cavity (13).

2. The cooktop heat shield of claim 1, wherein: at least one separator (2) is arranged in the lower layer cover (12), and the air supply opening (14) and the preheating cavity (13) can be separated into two relatively independent spaces by the separator (2).

3. The cooktop heat shield of claim 2, wherein: the separator (2) comprises two side plates which are vertically arranged at intervals, and a gap (21) which is communicated with the preheating cavity (13) and the air supply opening (14) is arranged between the two side plates.

4. The cooktop heat shield of claim 3, wherein: the air supply opening (14) sinks more than the preheating cavity (13), and a flow guiding slope (141) gradually inclining towards the air supply opening (14) from top to bottom is arranged on the air supply opening (14) and close to the gap (21).

5. The cooktop heat shield of claim 4, wherein: the bottom wall of the lower layer cover (12) comprises a first bottom wall (121) corresponding to the preheating cavity (13), and the upper surface of the first bottom wall (121) is provided with first preheating grooves (1211) arranged at intervals along the radial direction and second preheating grooves (1212) arranged at intervals along the circumferential direction.

6. The heat shield for a cooktop according to any one of claims 1 to 5, wherein: the cover body (1) is of a double-layer structure and comprises an upper layer cover (101) and a middle layer cover (102), an annular gap (103) is formed between the lower layer cover (12) and the middle layer cover (102), the annular gap (103) forms the air inlet part (15), and the lower layer cover (12) circumferentially and alternately extends towards the middle layer cover (102) through at least two connecting ribs (104).

7. The cooktop heat shield of claim 6, wherein: and pot support legs (1011) are arranged on the upper surface of the upper layer cover (101) along the circumferential direction.

8. A gas range using the heat shield of any one of claims 1 to 7, comprising a gas range panel (3) and a burner (4), wherein the burner (4) comprises:

a base (41);

the inner ring fire cover (42) is arranged above the base (41) and forms an inner ring gas mixing chamber (43) with the base (41);

the inner injection pipe (44) comprises an air inlet end (441) and an air outlet end (442), and the air outlet end (442) of the inner injection pipe (44) is communicated with the inner ring air mixing chamber (43);

the method is characterized in that:

the annular cavity (11) of the heat shield surrounds the burner (4) and rests on the gas stove panel (3), and the air supply opening (14) of the shield body (1) is aligned with the air outlet end (442) of the inner injection pipe (44).

9. The gas range of claim 8, wherein: the flame-retardant rubber sealing ring is characterized by further comprising an outer ring flame cover (45) and an outer injection pipe (46), wherein the outer ring flame cover (45) is also arranged on the base (41), an outer ring air mixing chamber (47) is formed between the outer ring flame cover and the base (41), the outer ring air mixing chamber (47) comprises an inner ring wall (471), an outer ring wall (472) and a bottom ring wall (473) which is connected with the inner ring wall (471) and the outer ring wall (472), the bottom ring wall (473) is provided with at least one lower notch (4731), an air outlet end (461) of the outer injection pipe (46) is communicated with the lower notch (4731), and the lower notch (4731) is covered with a flow homogenizing plate (5).

10. The gas range of claim 9, wherein: the lower notch (4731) is provided with a partition part (4731b), the partition part (4731b) divides the lower notch (4731) of the bottom ring wall (473) into a first lower notch (4732) and a second lower notch (4733), the first lower notch (4732) is provided with a first slope part (4732a) inclined towards the partition part (4731b), the second lower notch (4733) is provided with a second slope part (4733a) inclined towards the partition part (4731b), correspondingly, the outer ejector comprises a first outer ejector (6) with an air outlet end (461) communicated with the first lower notch (4732) and a second outer ejector (70) with an air outlet end (461) communicated with the second lower notch (4733).

11. The gas range of claim 10, wherein: the first lower notch (4732) is covered with a first flow distributing plate (5), the first flow distributing plate (5) comprises a first closed part (5a) corresponding to the first slope part (4732a) and a first open part (5b) corresponding to the first lower notch (4732) except the first closed part (5a), the first open part (5b) is provided with at least two first through holes (51b), and the first closed part (5a) gradually inclines upwards from the separating part (4731b) to the first open part (5 b).

12. Gas range according to claim 10 or 11, characterized in that: the second lower notch (4733) is covered with a second flow distributing plate (7), the second flow distributing plate (7) comprises a second closed part (7a) corresponding to the second slope part (4733a) and a second open part (7b) corresponding to the second closed part (7a) in the second lower notch (4733), the second open part (7b) is provided with at least two second through holes (71b), and the second closed part (7a) gradually inclines upwards from the separating part (4731b) to the second open part (7 b).