阅读说明：本技术 火焰筒及燃气轮机 (Flame tube and gas turbine ) 是由 静大亮 李珊珊 张哲铭 刘江帆 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种火焰筒及燃气轮机,包括筒体和多个肋片,筒体内设有燃气通道；多个肋片设在筒体的外周壁上,多个肋片沿着筒体的周向间隔排布,筒体上设有第一外周轮廓线和第二外周轮廓线,第一外周轮廓线和第二外周轮廓线间隔布置,多个肋片均设在第一外周轮廓线和第二外周轮廓线之间,且多个肋片的第一端位于筒体的第一外周轮廓线上,多个肋片的第二端位于筒体的第二外周轮廓线上,肋片的第一端和肋片的第二端在筒体的第一端至筒体的第二端的方向上错位布置,肋片的第一端和肋片的第二端之间具有在筒体的外周壁上的最短曲线,肋片沿着最短曲线延伸。本发明的火焰筒,具有较好的冷却效果,较高的冷却效率,且延长了燃气轮机的使用寿命。(The invention discloses a flame tube and a gas turbine, which comprise a tube body and a plurality of fins, wherein a gas channel is arranged in the tube body; a plurality of fins are established on the periphery wall of barrel, a plurality of fins are arranged along the circumference interval of barrel, be equipped with first periphery contour line and second periphery contour line on the barrel, first periphery contour line and second periphery contour line interval arrangement, a plurality of fins are all established between first periphery contour line and second periphery contour line, and the first end of a plurality of fins is located the first periphery contour line of barrel, the second end of a plurality of fins is located the second periphery contour line of barrel, the first end of fin and the second end of fin staggered arrangement in the direction of the first end of barrel to the second end of barrel, the shortest curve on the periphery wall of barrel has between the first end of fin and the second end of fin, the fin extends along the shortest curve. The flame tube has the advantages of good cooling effect and high cooling efficiency, and the service life of the gas turbine is prolonged.)

1. A flame tube, comprising:

a cylinder having a gas passage for hot gas to flow through, the cylinder having a first end and a second end, the first end of the cylinder being adapted for the hot gas to flow into the gas passage and the second end of the cylinder being adapted for the hot gas to flow out of the gas passage;

a plurality of fin, it is a plurality of the fin is established on the periphery wall of barrel, it is a plurality of the fin is along the circumference interval of barrel arranges, the fin has first end and second end, be equipped with first periphery contour line and second periphery contour line on the barrel, first periphery contour line with the second periphery contour line is along following the first end of barrel extremely the direction interval arrangement of the second end of barrel, it is a plurality of the fin is all established first periphery contour line with between the second periphery contour line, and it is a plurality of the first end of fin is located on the first periphery contour line of barrel, it is a plurality of the second end of fin is located on the second periphery contour line of barrel, the first end of fin with the second end of fin is in the first end of barrel extremely staggered arrangement in the direction of the second end of barrel, the first end of fin with have between the second end of fin be in the shortest on the periphery wall of barrel A curve, said ribs extending along said shortest curve.

2. The liner according to claim 1, wherein an angle α between a tangential direction of the shortest curve and a cross-section of the barrel is less than 90 degrees.

3. The flame tube according to claim 1, wherein a plurality of the fins are arranged in parallel at intervals, and a central angle β of the outer peripheral wall of the cylinder between two adjacent fins is 4 to 10 degrees.

4. The combustor basket of claim 1, wherein the barrel includes a first section and a second section, the first section and the second section being located between the first peripheral contour and the second peripheral contour, the first section having a peripheral side airflow velocity that is less than the second section, the first section having a peripheral side rib height dimension H1 that is greater than the second section having a peripheral side rib height dimension H2.

5. The liner as set forth in claim 4 wherein the first peripheral rib has a height dimension H1 of 0.8 mm to 1.2 mm.

6. The combustor basket of claim 1, wherein a height profile of at least some of the fins along a direction of extension of the fins or a cross-section of at least some of the fins is one or a combination of serrated, merlony, and laced.

7. The combustor basket of claim 1, wherein the fins have a width dimension W of 0.5 mm to 1.5 mm.

8. The combustor basket of claim 1, wherein the spacing L between two adjacent ribs on the outer peripheral wall of the basket body is 5 mm to 20 mm.

9. The flame holder of any of claims 1-8, wherein the fin has first and second oppositely disposed sides, each of the first and second sides extending in a direction of extension of the fin, the first side angled and smoothly connected to the peripheral wall of the barrel, and the second side angled and smoothly connected to the peripheral wall of the barrel.

10. A gas turbine engine comprising a combustor basket according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of cooling of flame tubes, in particular to a flame tube and a gas turbine.

Background

The combustion chamber of the gas turbine is internally provided with a fuel injection device, a flame tube, a transition section and the like, the fuel injection device is used for injecting fuel to the flame tube and mixing and burning the fuel and gas in the combustion chamber, and hot combustion gas generated by burning is conveyed to the turbine through the flame tube and the transition section. Since the liner needs to operate at high temperature conditions, the liner needs to be cooled efficiently to meet expected service life requirements. However, in the related art, the cooling effect of the flame tube has a large difference in different working states of different gas turbines, especially for a low-load point, the flow speed in the outer annular cavity of the flame tube is low, and a strong high-temperature region still exists in a part of regions, so that the cooling effect is reduced, and the service life of the gas turbine is influenced.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.

Therefore, the embodiment of the invention provides the flame tube, which has a good cooling effect and a high cooling efficiency, and the service life of the gas turbine is prolonged.

The embodiment of the invention also provides a gas turbine applying the flame tube.

A flame tube according to an embodiment of the invention includes: a cylinder having a gas passage for hot gas to flow through, the cylinder having a first end and a second end, the first end of the cylinder being adapted for the hot gas to flow into the gas passage and the second end of the cylinder being adapted for the hot gas to flow out of the gas passage; a plurality of fin, it is a plurality of the fin is established on the periphery wall of barrel, it is a plurality of the fin is along the circumference interval of barrel arranges, the fin has first end and second end, be equipped with first periphery contour line and second periphery contour line on the barrel, first periphery contour line with the second periphery contour line is along following the first end of barrel extremely the direction interval arrangement of the second end of barrel, it is a plurality of the fin is all established first periphery contour line with between the second periphery contour line, and it is a plurality of the first end of fin is located on the first periphery contour line of barrel, it is a plurality of the second end of fin is located on the second periphery contour line of barrel, the first end of fin with the second end of fin is in the first end of barrel extremely staggered arrangement in the direction of the second end of barrel, the first end of fin with have between the second end of fin be in the shortest on the periphery wall of barrel A curve, said ribs extending along said shortest curve.

According to the flame tube disclosed by the embodiment of the invention, the flame tube has a better cooling effect and higher cooling efficiency, and the service life of the gas turbine is prolonged.

In some embodiments, the angle α between the tangent of the shortest curve and the cross-section of the barrel is less than 90 degrees.

In some embodiments, a plurality of the fins are arranged in parallel at intervals, and a central angle β corresponding to the outer peripheral wall of the cylinder between two adjacent fins is 4 to 10 degrees.

In some embodiments, the cartridge includes a first section and a second section, the first section and the second section being located between the first peripheral contour and the second peripheral contour, the first section having a peripheral side with an airflow velocity that is less than an airflow velocity of a peripheral side of the second section, the first section having a peripheral side rib height dimension H1 that is greater than a peripheral side rib height dimension H2 of the second section.

In some embodiments, the first peripheral side rib has a height dimension H1 of 0.8 mm to 1.2 mm.

In some embodiments, a height profile of at least a portion of the fins along an extending direction of the fins or a cross-section of at least a portion of the fins is one or a combination of saw-tooth shape, city wall shape, and lace shape.

In some embodiments, the width dimension W of the ribs is 0.5 mm to 1.5 mm.

In some embodiments, the distance L between two adjacent ribs on the outer circumferential wall of the cylinder is 5 mm to 20 mm.

In some embodiments, the rib has a first side face and a second side face which are oppositely arranged, the first side face and the second side face both extend along the extending direction of the rib, the first side face and the peripheral wall of the cylinder body form an included angle and are smoothly connected, and the second side face and the peripheral wall of the cylinder body form an included angle and are smoothly connected.

The gas turbine according to the embodiment of the invention comprises a flame tube, wherein the flame tube is the flame tube in any one of the embodiments.

Drawings

FIG. 1 is a perspective view of the overall structure of a flame tube according to an embodiment of the invention.

FIG. 2 is a schematic side view of the liner of FIG. 1.

Fig. 3 is a partially enlarged schematic view at a in fig. 2.

Fig. 4 is a schematic cross-sectional view at a-a in fig. 2.

Fig. 5 is a partially enlarged schematic view at B in fig. 4.

Fig. 6 is a schematic cross-sectional view at B-B in fig. 2.

Fig. 7 is a partially enlarged schematic view at C in fig. 6.

Fig. 8 is a partially enlarged schematic view at C in fig. 6 according to another embodiment of the present invention.

FIG. 9 is a schematic view of a serrated rib in accordance with an embodiment of the present invention.

FIG. 10 is a schematic view of a city wall fin according to an embodiment of the invention.

FIG. 11 is a schematic view of a lace-like rib according to an embodiment of the present invention.

FIG. 12 is a schematic diagram of a combination rib according to an embodiment of the present invention.

Reference numerals:

a cylinder body 1; a gas channel 11; a first peripheral contour line 12; a second peripheral outline 13;

a rib 2; a first side 21; a second side 22; rib outer peripheral surfaces 23; a flow guide groove 24.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

As shown in fig. 1 to 8, the flame tube according to the embodiment of the present invention includes a cylindrical body 1 and a plurality of ribs 2.

A gas channel 11 for hot gas circulation is arranged in the cylinder body 1, the cylinder body 1 is provided with a first end and a second end, the first end of the cylinder body 1 is suitable for hot gas to flow into the gas channel 11, and the second end of the cylinder body 1 is suitable for hot gas to flow out of the gas channel 11.

Specifically, as shown in fig. 1 and fig. 2, a gas channel 11 is provided in the cylinder 1, the first end of the cylinder 1 is the front end of the cylinder 1, and the second end of the cylinder 1 is the rear end of the cylinder 1, during use, hot gas can flow into the gas channel 11 from the front end of the cylinder 1, and then flow out from the rear end of the cylinder 1.

The plurality of fins 2 are arranged on the peripheral wall of the cylinder 1, the plurality of fins 2 are arranged at intervals along the circumferential direction of the cylinder 1, the fins 2 have a first end and a second end, the cylinder 1 is provided with a first peripheral contour line 12 and a second peripheral contour line 13, the first peripheral contour line 12 and the second peripheral contour line 13 are arranged at intervals along the direction from the first end of the cylinder 1 to the second end of the cylinder 1, the plurality of fins 2 are all arranged between the first peripheral contour line 12 and the second peripheral contour line 13, the first ends of the plurality of fins 2 are positioned on the first peripheral contour line 12 of the cylinder 1, the second ends of the plurality of fins 2 are positioned on the second peripheral contour line 13 of the cylinder 1, the first ends of the fins 2 and the second ends of the fins 2 are arranged in a staggered manner in the direction from the first end of the cylinder 1 to the second end of the cylinder 1, and the shortest curve on the peripheral wall of the cylinder 1 is arranged between the first ends of the fins 2 and the second ends of the fins 2, the ribs 2 extend along the shortest curve.

Specifically, as shown in fig. 1 and 2, the outer peripheral wall of the cylinder 1 has a first outer peripheral contour line 12 and a second outer peripheral contour line 13, it should be noted that the first outer peripheral contour line 12 and the second outer peripheral contour line 13 may be virtual contour lines which are both virtual contour lines on the outer peripheral wall of the cylinder 1, and the first outer peripheral contour line 12 and the second outer peripheral contour line 13 are both extended and closed into a circle along the circumferential direction of the cylinder 1, wherein the first outer peripheral contour line 12 and the second outer peripheral contour line 13 are arranged at intervals along the front-to-rear direction, and wherein the second outer peripheral contour line 13 is located at the rear side of the first outer peripheral contour line 12.

The plurality of fins 2 are each provided between the first outer peripheral contour line 12 and the second outer peripheral contour line 13, and the plurality of fins 2 are arranged at intervals along the circumferential direction of the cylinder 1. As shown in fig. 2, a first end of each of the fins 2 is a front end of the fin 2, a second end of each of the fins 2 is a rear end of the fin 2, and the first end of the fin 2 and the second end of the fin 2 are arranged in a staggered manner in a front-rear direction by a certain angle, that is, the first end of the fin 2 and the second end of the fin 2 are not opposite to each other in the front-rear direction. The first ends of the fins 2 and the second ends of the fins 2 can be regarded as two points on the outer peripheral wall of the cylinder 1, the two points having a shortest distance on the outer peripheral wall of the cylinder 1, the shortest distance being a curve, each of the fins 2 being arranged extending along the shortest distance between the first end of the fin 2 and the second end of the fin 2, i.e., the fins 2 on the outer peripheral wall of the cylinder 1 are arranged obliquely with respect to the axial direction of the cylinder 1.

In the present embodiment, the main flow on the outer peripheral side of the flame tube flows in the rear-to-front direction.

According to the flame tube of the embodiment of the invention, the downstream of the rib outer peripheral surface 23 can form the separation vortex, and the separation vortex can destroy the main flow structure of the outer side surface of the flame tube, so that the heat exchange of the outer peripheral side of the flame tube can be enhanced. In addition, as shown in fig. 8, a guide groove 24 is formed between the spirally wound fins 2 and the flame tube, turbulence is formed in the guide groove 24, the guide groove 24 is separated by the fins 2, the turbulence in the guide groove 24 is relatively independent and does not interfere with each other, when a local main flow changes, a turbulence structure in the adjacent guide groove 24 is not affected, and therefore, the cooling effect is more stable. The fins 2 arranged obliquely can increase the contact area between the fins 2 and the main flow, further increasing the cooling efficiency.

In addition, because the fins 2 extend along the shortest distance between the first ends of the fins 2 and the second ends of the fins 2, on one hand, the arrangement form of the fins 2 can be simplified, and the consumable material of the fins 2 is reduced, so that the cost of the flame tube is reduced, and on the other hand, the flow guide grooves 24 formed between two adjacent fins 2 are more in accordance with the fluid design, thereby being beneficial to accelerating the flow velocity of the airflow in the flow guide grooves 24 and further improving the cooling effect of the flame tube.

Due to the improvement of the cooling effect and the cooling efficiency of the flame tube, the flame tube has better operation stability and longer service life in the use process, thereby prolonging the service life of the gas turbine.

In some embodiments, the angle α between the tangent of the shortest curve and the cross-section of the barrel 1 is less than 90 degrees. Specifically, as shown in fig. 3, the tangential direction of the shortest curve is the tangential direction of each point on the shortest curve, for example, the first end of the rib 2 can be regarded as a point on the outer peripheral wall of the cylinder 1, the tangential direction of the point can be regarded as the extending direction of the rib 2 in fig. 3, the tangential direction of the point and the cross section of the cylinder 1 form an included angle α, and the included angle α can be any value less than 90 degrees, for example, the included angle α can be 3 degrees, 5 degrees, 10 degrees, 15 degrees, 25 degrees, 34 degrees, 60 degrees, 78 degrees, 88 degrees, and the like.

It should be noted that the included angles α between the tangential direction of any point on the shortest curve and the cross section (the section plane perpendicular to the front-back direction) of the cylinder 1 are all smaller than 90 degrees.

In some embodiments, the plurality of fins 2 are arranged in parallel at intervals, and the central angle β of the outer circumferential wall of the cylinder 1 between two adjacent fins 2 is 4 to 10 degrees. Specifically, as shown in fig. 4 and 5, on the cross section of the cylinder 1, the cross section of two adjacent fins 2 has a central angle β therebetween, and the central angle β may be any value from 4 degrees to 10 degrees, for example, the central angle β may be 4 degrees, 5 degrees, 6 degrees, 7 degrees, 8 degrees, 9 degrees, 10 degrees, and the like. The central angle beta is selected in the above numerical range, on the one hand, the condition that the distribution density of the fins 2 on the periphery side of the cylinder body 1 is smaller due to the overlarge diversion groove 24 can be avoided, further, the condition that the cooling effect of the flame tube is poor due to the small distribution density of the fins 2 is avoided, on the other hand, the size of the cross section of the diversion groove 24 is controlled within a reasonable range, so that the flow velocity in the diversion groove 24 and the generated turbulence effect can be guaranteed, and the further promotion of the cooling effect and the cooling efficiency of the flame tube is facilitated.

In some embodiments, the cartridge 1 comprises a first section and a second section, the first section and the second section being located between the first peripheral contour 12 and the second peripheral contour 13, the airflow velocity on the peripheral side of the first section being less than the airflow velocity on the peripheral side of the second section, the height dimension H1 of the fins 2 on the peripheral side of the first section being greater than the height dimension H2 of the fins 2 on the peripheral side of the second section.

Specifically, as shown in fig. 2, the barrel 1 may include a first section (not shown) and a second section (not shown) in the front-to-rear direction, both of which are axial sections of the barrel 1, during use of the liner, the gas flow rate at the outer periphery of the first segment is less than the gas flow rate at the outer periphery of the second segment, it being noted that the position of the first and second segments may be determined empirically and/or by means of sensor monitoring, for example, in the design stage, the flame tube may be first installed in the combustion chamber, and then a plurality of sensors may be provided on the outer circumferential side of the flame tube, the sensors may sense the air flow velocity, and then simulating the operation condition of the gas turbine, and confirming the position of the first section on the cylinder body 1 by monitoring the air flow speed of each section of the cylinder body 1, wherein the rest positions on the cylinder body 1 except the first section can be regarded as the second section.

As shown in fig. 8, the height dimension H1 of the element 2 corresponding to the first segment is greater than the height dimension H2 of the element 2 corresponding to the second segment. The larger the height dimension of the fins 2, the more remarkable the turbulent flow effect of the fins 2, and the better the cooling effect and cooling efficiency at that point, whereby the cooling performance under the condition of the load (low flow rate) on the outer peripheral side of the cylinder 11 can be improved by increasing the height dimension H1 of the first-stage outer peripheral-side fins 2.

In some embodiments, the first section is plural, the second section is plural, and the plural first sections and the plural second sections are alternately arranged in a direction from the first end of the barrel 1 to the second end of the barrel 1.

Specifically, the outer peripheral side of the cylinder 1 may have a plurality of load positions (low flow rate positions), and correspondingly, the cylinder 1 has a plurality of first segments arranged at intervals along the extending direction of the cylinder 1. It should be noted that, except the first section, the cylinder 1 can be regarded as the second section, and therefore, the plurality of first sections and the plurality of second sections are alternately arranged one by one along the extending direction of the cylinder 1. Therefore, each position on the outer circumferential side of the flame tube can be ensured to have a good cooling effect.

In some embodiments, the height of the fins 2 on the outer periphery of the first section varies along the extension of the fins 2.

Specifically, the height dimension H of the first-stage outer circumferential-side fins 2 may be gradually larger, smaller, or first larger and then smaller in the front-to-rear direction. Because the height dimension of the fins 2 gradually changes along with the extension direction of the fins 2, the disturbance of the main flow structure can be further increased due to the change of the height dimension, and a disturbed flow and a secondary flow vortex are formed, so that the cooling efficiency of the flame tube is further improved. Due to the enhanced cooling effect and cooling efficiency of the combustor basket, the service life of the combustor basket is increased and the operation is more stable, thereby facilitating the extension of the service life of the gas turbine.

In some embodiments, the height dimension H1 of the first peripheral rib section 2 is 0.8 mm to 1.2 mm.

Specifically, as shown in fig. 8, the height dimension H1 of the fins 2 on the outer peripheral side of the first stage may be any value between 0.8 mm and 1.2 mm, for example, the height dimension H1 may be 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, or the like. The height H1 is designed in the above-mentioned range to achieve a turbulent flow effect on the one hand and to avoid the situation that the fins 2 are high enough to disturb the main flow on the other hand.

In some embodiments, the height profile of at least a part of the fins 2 in the extension direction of the fins 2 or the cross-section of at least a part of the fins 2 is one or a combination of saw-tooth, city wall, lace.

Specifically, as shown in fig. 7 and 8, the cross section of the rib 2 is shown in the figure, the height section of the extending direction of the rib 2 is a section perpendicular to the cross section of the rib 2, and the section of the extending direction of the rib 2 may be one of a saw-tooth shape, a city wall shape and a lace shape, or a combination of two or more of the saw-tooth shape, the city wall shape and the lace shape, as shown in fig. 9 to 12. Similarly, the cross section of the rib 2 may be one of a saw-tooth shape, a city wall shape and a lace shape, or a combination of two or more of a saw-tooth shape, a city wall shape and a lace shape, as shown in fig. 9 to 12.

Therefore, the turbulent flow of the main flow structure can be further enhanced, and the cooling effect and the cooling efficiency are further enhanced.

In some embodiments, the width dimension W of the fins 2 is 0.5 mm to 1.5 mm. Specifically, as shown in fig. 7, the width dimension W of the rib 2 may be any value between 0.5 mm and 1.5 mm, for example, the width dimension W may be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc.

In some embodiments, the distance L between two adjacent fins 2 on the outer circumferential wall of the cylinder 1 is 5 mm to 20 mm. Specifically, as shown in fig. 7, the pitch L of the ribs 2 may be any value between 5 mm and 20 mm, for example, the pitch L may be 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 17 mm, 18 mm, 19 mm, 20 mm, and the like.

In some embodiments, the fins 2 have a first side 21 and a second side 22 arranged oppositely, the first side 21 and the second side 22 both extend along the extension direction of the fins 2, the first side 21 is angled and smoothly connected with the peripheral wall of the cylinder 1, and the second side 22 is angled and smoothly connected with the peripheral wall of the cylinder 1.

Specifically, as shown in fig. 8, the first side 21 is a front side of the rib 2, the second side 22 is a rear side of the rib 2, the first side 21 and the second side 22 are spirally wound on an outer circumferential side of the cylinder 1, the first side 21 is substantially perpendicular to an outer circumferential wall of the cylinder 1, the first side 21 is in rounded transition with the outer circumferential wall of the cylinder 1, the second side 22 is substantially perpendicular to the outer circumferential wall of the cylinder 1, and the second side 22 is in rounded transition with the outer circumferential wall of the cylinder 1. From this, on the one hand can guarantee the joint strength of fin 2 and barrel 1, on the other hand has still avoided the condition that produces the dead angle in the water conservancy diversion recess 24 for the torrent in the water conservancy diversion recess 24 can smoothly flow, is favorable to improving the heat dissipation.

A gas turbine according to an embodiment of the present invention is described below.

According to the embodiment of the invention, the gas turbine comprises the flame tube, and the flame tube can be the flame tube described in the embodiment. Specifically, the gas turbine comprises a combustion chamber, a flame tube, a fuel injection device and a transition section, wherein the flame tube is arranged in the combustion chamber, the fuel injection device is arranged at the front end of the flame tube, the transition section is connected to the rear end of the flame tube, the transition section is a transition pipe, and the transition section is connected between the flame tube and the turbine. Part of air compressed by the air compressor flows from back to front along the peripheral side of the flame tube, exchanges heat with the tube body and the fins on the peripheral side of the flame tube, and then cools the flame tube, returns back to flow into the flame tube through the front end device of the flame tube, and is mixed with fuel sprayed by the fuel spraying device for combustion.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.