阅读说明：本技术 一种内嵌管式蜂窝填充薄壁结构的梯度吸能装置 (Gradient energy absorption device of embedded pipe type honeycomb filling thin-wall structure ) 是由 谢素超 汪浩 冯哲骏 刘项 马闻 井坤坤 于 2021-07-08 设计创作，主要内容包括：本发明公开了一种内嵌管式蜂窝填充薄壁结构的梯度吸能装置,其包括：薄壁管和蜂窝块。蜂窝块内嵌填充管,利用填充管的材质和数量上的差异形成阶梯吸能效果。同时,在蜂窝块的孔洞中嵌有填充管,蜂窝块在压缩过程中,各胞元折叠变形,在完全致密化后内部仍然保持了大量六边形规则空隙,将填充管嵌入蜂窝块,能够充分利用这些空隙,同时根据填充管与蜂窝胞元的耦合作用,内嵌结构整体的吸能能力大于蜂窝块吸能能力与填充管吸能能力的总和,从而能够有效提升结构整体的吸能性能。不仅如此,由于各蜂窝块内填充管的长度、材质、数量和排布方式不同,导致各横切面内填充管的吸能能力存在差异,从而进一步细化阶梯吸能效果。(The invention discloses a gradient energy absorption device of an embedded tubular honeycomb filling thin-wall structure, which comprises: thin walled tubes and honeycomb blocks. The honeycomb block is embedded with a filling pipe, and a step energy absorption effect is formed by utilizing the difference of the material and the quantity of the filling pipe. Meanwhile, filling pipes are embedded in holes of the honeycomb block, each cell element is folded and deformed in the compression process of the honeycomb block, a large number of regular hexagonal gaps are still kept inside the honeycomb block after the honeycomb block is completely densified, the filling pipes are embedded into the honeycomb block, the gaps can be fully utilized, and meanwhile, according to the coupling effect of the filling pipes and the honeycomb cell elements, the integral energy absorption capacity of the embedded structure is larger than the sum of the energy absorption capacity of the honeycomb block and the energy absorption capacity of the filling pipes, so that the integral energy absorption performance of the structure can be effectively improved. Moreover, because the length, the material, the quantity and the arrangement mode of the filling pipes in each honeycomb block are different, the energy absorption capacity of the filling pipes in each cross section is different, and the stepped energy absorption effect is further refined.)

1. The utility model provides an embedded tubular honeycomb fills thin wall structure's gradient energy-absorbing device which characterized in that includes: a thin-walled tube (1) and a honeycomb block (2);

the thin-walled tube (1) is a cylindrical shell extending longitudinally, a plurality of parallel holes extending longitudinally are formed in the honeycomb block (2), and filling tubes are embedded in the holes; the honeycomb blocks (2) with at least two lengths are filled in the thin-walled tube (1) along the extending direction of the thin-walled tube (1), and the honeycomb blocks (2) on the same cross section have the same length;

the thin-walled tube (1) and the honeycomb block (2) can be compressed and deformed when being subjected to longitudinal extrusion.

2. The gradient energy absorption device of the embedded pipe type honeycomb filling thin-wall structure is characterized in that the honeycomb blocks (2) comprise long honeycomb blocks (21) and short honeycomb blocks (22), and the honeycomb blocks (2) on the same cross section form a honeycomb block group; the front section of the thin-walled tube (1) is filled with a plurality of long honeycomb block groups, and the rear section of the thin-walled tube is filled with a plurality of short honeycomb block groups.

3. The gradient energy absorption device of the embedded pipe type honeycomb filling thin-wall structure is characterized in that the holes are in a regular hexagon shape, and the holes penetrate through the honeycomb block (2).

4. The gradient energy absorption device of the embedded pipe type honeycomb filled thin-wall structure is characterized in that a front end pipe cover of the thin-wall pipe (1) is provided with a front end plate (11), and a rear end pipe cover is provided with a rear end plate (12); and partition plates (13) are arranged among the honeycomb block groups.

5. The gradient energy absorption device of the embedded pipe type honeycomb filled thin-wall structure according to claim 4, characterized by further comprising a guide rod (3) with one end penetrating into the thin-wall pipe (1);

the rear end plate (12) and the partition plate (13) are both provided with guide holes (14); one end of the guide rod (3) penetrates through the guide hole (14) from back to front and then abuts against the front end plate (11).

6. The gradient energy absorption device of the embedded pipe type honeycomb filling thin-wall structure is characterized in that the guide rod (3) is H-shaped steel or I-shaped steel; the honeycomb blocks (2) are symmetrically distributed along the guide rod (3).

7. The gradient energy absorption device of the embedded tubular honeycomb filled thin-wall structure as recited in claim 2, characterized in that the filling tube comprises a long tube (41); the long pipes (41) are embedded in the holes of the long honeycomb blocks (21), and the long pipes (41) in the long honeycomb blocks (21) are arranged in the same honeycomb block group.

8. The gradient energy absorption device of an embedded pipe type honeycomb filling thin-wall structure as claimed in claim 7, wherein the number of the long pipes (41) in each long honeycomb block group increases from the front end to the rear end.

9. The gradient energy absorption device of an embedded tube type honeycomb filling thin-wall structure as claimed in claim 8, wherein the long tube (41) is a carbon fiber reinforced composite material circular tube, and the long tube (41) is as long as the long honeycomb block (21).

10. The gradient energy absorption device of the embedded tubular honeycomb filled thin-wall structure according to claim 2, characterized in that the filling tube comprises a short tube (42); the short pipes (42) are embedded in the holes of the short honeycomb blocks (22), and the short pipes (42) in the short honeycomb blocks (22) in the same honeycomb block group are arranged in the same mode.

11. The gradient energy absorption device of an embedded pipe type honeycomb filling thin-wall structure according to claim 10, characterized in that the number of the short pipes (42) in each short honeycomb block group is increased from the front end to the rear end.

12. The gradient energy absorption device of an embedded pipe type honeycomb filling thin-wall structure according to claim 11, characterized in that the short pipe (42) is an aluminum round pipe, and the short pipe (42) is as long as the short honeycomb block (22).

13. The gradient energy absorption device of the embedded pipe type honeycomb filling thin-wall structure according to any one of claims 4 to 6, characterized in that a climbing prevention tooth (15) is installed on one surface of the front end plate (11) far away from the thin-wall pipe (1), and a plurality of transverse tooth grooves are formed on one surface of the climbing prevention tooth (15) far away from the front end plate (11).

14. The gradient energy absorption device of an embedded pipe type honeycomb filling thin-wall structure according to any one of claims 1 to 12, characterized in that an induction groove (16) is formed at a front end pipe orifice of the thin-wall pipe (1).

Technical Field

The invention mainly relates to the technical field of energy absorption devices, in particular to a gradient energy absorption device with an embedded tubular honeycomb filling thin-wall structure.

Background

With the rapid development of the rail transit industry in China in recent years, the running speed of trains is continuously improved, and the safety problem of the trains is more and more emphasized. Once a collision accident occurs to the train, huge casualties can be brought, so that the passive safety protection capability of the train is particularly important. The special energy absorption device is widely applied to an energy dissipation system in the traffic field, can convert kinetic energy in a collision and impact process into structural plastic deformation energy, and is generally arranged at the front end of a vehicle to absorb most collision kinetic energy when collision occurs so as to reduce casualties to the maximum extent in order to improve the passive safety protection capability of a train.

The metal thin-wall structure is widely applied to a special energy absorption device as an energy absorption structure with low cost, high strength-weight ratio and high energy absorption efficiency, but with the improvement of the collision safety speed standard, a single thin-wall structure is difficult to meet the energy consumption requirement under the high standard, a light high-strength honeycomb structure is used as a core material to be filled in the thin-wall structure, and the energy absorption device formed by combining the honeycomb filled metal thin-wall structures is known as a light high-efficiency special energy absorption device with high stroke ratio.

In the design of the crash resistance of a railway vehicle, the energy absorption structure is generally expected to have multi-stage ladder energy absorption capacity, and the sequential deformation of the train structure from front to back in low-speed to high-speed collision is met through the gradient energy absorption design of a coupler buffer device, the energy absorption device, a vehicle end easy-deformation area and a passenger room, so that the safety of passengers is protected to the maximum extent. Similarly, in order to obtain a more excellent energy absorption effect, it is also desirable to achieve multi-level gradient deformation energy absorption inside the energy absorption device, so that the impact of the collision can be further reduced. However, the energy absorption device in the prior art is often single in structure and cannot achieve a controllable multi-stage energy absorption effect.

Disclosure of Invention

The invention mainly aims to overcome the defects in the prior art and solve the problem that the conventional energy absorption device cannot achieve a controllable multistage energy absorption effect.

In order to achieve the purpose, the invention discloses a gradient energy absorption device of an embedded tubular honeycomb filling thin-wall structure, which comprises: thin wall tubes and honeycomb blocks;

the thin-wall pipe is a cylindrical shell extending longitudinally, the honeycomb block is provided with a plurality of parallel holes extending longitudinally, and filling pipes are embedded in the holes; the honeycomb blocks with at least two lengths are filled in the thin-wall pipe along the extending direction of the thin-wall pipe, and the lengths of the honeycomb blocks on the same cross section are consistent;

the thin-walled tube and the honeycomb block can be compressed and deformed when being subjected to longitudinal extrusion.

As a further improvement of the above technical solution:

the honeycomb blocks comprise long honeycomb blocks and short honeycomb blocks, and the honeycomb blocks positioned on the same cross section form a honeycomb block group; the front section of the thin-walled tube is filled with a plurality of long honeycomb block groups, and the rear section of the thin-walled tube is filled with a plurality of short honeycomb block groups.

The holes are regular hexagons and penetrate through the honeycomb blocks.

The front end pipe orifice cover of the thin-walled pipe is provided with a front end plate, and the rear end pipe orifice cover is provided with a rear end plate; and partition plates are arranged among the honeycomb block groups.

The energy absorption device also comprises a guide rod with one end penetrating through the thin-wall pipe;

the rear end plate and the partition plate are both provided with guide holes; one end of the guide rod penetrates through the guide hole from back to front and then abuts against the front end plate.

The guide rod is H-shaped steel or I-shaped steel; the honeycomb blocks are symmetrically distributed along the guide rod.

The filling tube comprises a long tube; the long honeycomb block is characterized in that the long pipes are embedded in the holes of the long honeycomb block and are arranged in the same honeycomb block group.

The number of the long tubes in each long honeycomb block group is sequentially increased from the front end to the rear end.

The long pipe is a carbon fiber reinforced composite material circular pipe, and is as long as the long honeycomb block.

The fill tube comprises a short tube; the short pipes are embedded in the holes of the short honeycomb blocks, and the short pipes in the short honeycomb blocks in the same honeycomb block group are arranged consistently.

In each short honeycomb block group, the number of the short pipes is increased from the front end to the rear end in sequence.

The short pipe is an aluminum circular pipe, and the short pipe is as long as the short honeycomb block.

The front end plate is far away from one side of the thin-walled tube is provided with anti-climbing teeth, and the anti-climbing teeth are away from one side of the front end plate to form a plurality of transverse tooth grooves.

An inducing groove is formed at the front end pipe orifice of the thin-wall pipe.

Compared with the prior art, the invention has the advantages that:

the honeycomb block is embedded with a filling pipe, and a step energy absorption effect is formed by utilizing the difference of the material and the quantity of the filling pipe. Meanwhile, in order to further improve the energy absorption effect, filling pipes are embedded in holes of the honeycomb block, each cell element is folded and deformed in the compression process of the honeycomb block, a large number of regular hexagonal gaps are still kept inside the honeycomb block after the honeycomb block is completely densified, the filling pipes are embedded into the honeycomb block, the gaps can be fully utilized, and meanwhile, according to the coupling effect of the filling pipes and the honeycomb cell elements, the integral energy absorption capacity of the embedded structure is greater than the sum of the energy absorption capacity of the honeycomb block and the energy absorption capacity of the filling pipes, so that the integral energy absorption performance of the structure can be effectively improved. Moreover, because the length, the material, the quantity and the arrangement mode of the filling pipes in each honeycomb block are different, the energy absorption capacity of the filling pipes in each cross section is different, and the stepped energy absorption effect is further refined.

Drawings

FIG. 1 is a schematic structural diagram of a gradient energy absorption device with an embedded tubular honeycomb filled thin-wall structure according to the present invention;

FIG. 2 is an exploded view of the gradient energy absorber with an embedded tubular honeycomb filled thin-wall structure according to the present invention;

FIG. 3 is a schematic diagram of a partial explosion of a gradient energy absorption device with an embedded tubular honeycomb filled thin-wall structure according to the present invention;

FIG. 4 is a schematic view of arrangement of long pipes and short pipes in a honeycomb block;

FIG. 5 is a schematic view of the impact compression process of the gradient energy absorption device with an embedded tubular honeycomb filled thin-wall structure according to the present invention;

FIG. 6 is a schematic diagram showing the comparison between the gradient energy absorption device of the embedded tubular honeycomb filled thin-wall structure of the present invention and the energy absorption of the prior art;

fig. 7 is a schematic view of the mounting position on the vehicle body.

The reference numerals in the figures denote: 1. a thin-walled tube; 11. a front end plate; 12. a rear end plate; 13. a partition plate; 14. a guide hole; 15. anti-climbing teeth; 16. a guiding groove; 2. a honeycomb block; 21. a long honeycomb block; 22. a short honeycomb block; 3. a guide bar; 41. a long tube; 42. a short pipe; 5. an energy absorbing device.

Detailed Description

The invention will be described in further detail below with reference to the drawings and specific examples.

The invention discloses a gradient energy absorption device with an embedded tubular honeycomb filling thin-wall structure.

As shown in fig. 1 to 6, the gradient energy absorption device of the embedded tubular honeycomb filled thin-wall structure of the embodiment includes: a thin-walled tube 1 and a honeycomb block 2;

the thin-wall pipe 1 is a columnar shell extending longitudinally, the honeycomb block 2 is provided with a plurality of parallel holes extending longitudinally, and filling pipes are embedded in the holes; the honeycomb blocks 2 with at least two lengths are filled in the thin-walled tube 1 along the extending direction of the thin-walled tube 1, and the lengths of the honeycomb blocks 2 on the same cross section are consistent;

the thin-wall pipe 1 and the honeycomb block 2 can be compressed and deformed when being subjected to longitudinal extrusion.

Through the honeycomb piece 2 of filling different length in thin wall pipe 1, and at the embedded filler pipe in hole, utilize the material of filler pipe and difference in quantity to form the ladder energy-absorbing effect, honeycomb piece 2 is in compression process, each cell folding deformation, inside a large amount of hexagonal regular gaps still kept after complete densification, imbed honeycomb piece 2 with the filler pipe, can make full use of these gaps, simultaneously according to the coupling effect of filler pipe and honeycomb cell, the holistic energy-absorbing ability of embedded structure is greater than the total of 2 energy-absorbing ability of honeycomb piece and filler pipe energy-absorbing ability, thereby can effectively promote the holistic energy-absorbing performance of structure. Moreover, because the length, the material, the quantity and the arrangement mode of the filling pipes in each honeycomb block 2 are different, the energy absorption capacity of the filling pipes in each cross section is different, and the stepped energy absorption effect is further refined.

Referring to fig. 2, in the present embodiment, the honeycomb block 2 includes a long honeycomb block 21 and a short honeycomb block 22, and the honeycomb blocks 2 located on the same cross section form a honeycomb block group; the front section of the thin-wall pipe 1 is filled with a plurality of long honeycomb block groups, and the rear section is filled with a plurality of short honeycomb block groups.

In order to further enhance controllability and avoid stress unevenness caused by disordered compression of the honeycomb blocks 2, the long honeycomb blocks 21 and the short honeycomb blocks 22 are respectively positioned on different cross sections, and when impact force is transmitted along the longitudinal direction, stress of each cross section is basically consistent, so that compression processes of the honeycomb blocks 2 on each cross section are basically the same. Moreover, the compression resistance of the short honeycomb blocks 22 is superior to that of the long honeycomb blocks 21, the long honeycomb block groups are arranged at the front section, and the short honeycomb block groups are arranged at the rear section, so that the effect of sequential compression from front to back can be realized.

In this embodiment, the holes are regular hexagons and penetrate through the honeycomb block 2.

Set the hole to regular hexagon and can exert honeycomb's steady energy-absorbing characteristic to the at utmost, when assaulting the emergence, the compression process of honeycomb piece 2 is steady relatively, more can promote the security performance.

In the embodiment, the front end pipe orifice cover of the thin-walled pipe 1 is provided with a front end plate 11, and the rear end pipe orifice cover is provided with a rear end plate 12; partition plates 13 are arranged between the honeycomb block groups.

Although each honeycomb block group is composed of honeycomb blocks 2 with the same length, the honeycomb blocks 2 with the same specification can also bring compression random deformation response due to the difference in actual processing, in order to further enhance the compression synchronism of each honeycomb block group, a front end plate 11 is arranged at the front end pipe opening cover of the thin-wall pipe 1, a rear end plate 12 is arranged at the rear end pipe opening cover, and a partition plate 13 is arranged between each honeycomb block group. The front end plate 11, the rear end plate 12 and the partition plate 13 are made of rigid materials and are arranged perpendicular to the extending direction of the honeycomb block 2, and after impact force acts on the front end plate 11, the front end plate 11 can disperse the impact force to the thin walls of the holes of the adjacent honeycomb blocks 2, so that the stress of the honeycomb blocks 2 is adjusted to be more uniform. In a similar way, the partition plates 13 can also realize the same function, so that the stress of each stage of honeycomb plate group is optimized, and the stable compression is realized.

In the embodiment, the energy absorption device also comprises a guide rod 3 with one end penetrating through the thin-wall pipe 1;

the rear end plate 12 and the partition plate 13 are both formed with guide holes 14; one end of the guide rod 3 is respectively connected with the front end plate 11 after passing through the guide hole 14 from back to front.

When impact occurs, the thin-wall pipe 1 and the honeycomb block 2 are compressed, the thin-wall pipe 1 and the honeycomb block 2 lose support in the transverse direction, and the compression direction is deviated from the longitudinal direction probably due to uneven stress, so that the transmission of force is influenced, and the energy absorption effect is poor due to the heaviest weight. In order to control the compression always in the longitudinal direction, a guide bar 3 is provided in the energy absorption device. The guide rods 3 are arranged along the longitudinal direction and do not participate in compression, and when impact occurs, the guide rods are always arranged along the longitudinal direction to provide transverse support for the thin-wall pipe 1 and the honeycomb block 2, so that the compression direction can be controlled not to deviate.

In this embodiment, the guide bar 3 is H-shaped steel or i-shaped steel; the honeycomb blocks 2 are symmetrically distributed along the guide rods 3.

The H-shaped steel or I-shaped steel has good mechanical properties, is easy to produce and process, and the honeycomb blocks 2 are symmetrically arranged along the guide rod 3, so that the overall stress is more balanced.

In this embodiment, the filling tube comprises a long tube 41; the long pipes 41 are embedded in the holes of the long honeycomb block 21, and the long pipes 41 in the long honeycomb block 21 in the same honeycomb block group are arranged in a consistent manner.

The long tubes 41 with the same number and the same arrangement mode can basically keep the same mechanical property, and in order to balance the stress of each honeycomb block group as much as possible, the long tubes 41 are uniformly arranged in the long honeycomb blocks 21 in the same group.

In this embodiment, the number of the long tubes 41 in each long honeycomb block group increases from the front end to the rear end.

The greater the number of the long tubes 41, the greater the resistance to the impact force. In order to achieve the effect of sequential compression from front to back, the number of the long tubes 41 in each long honeycomb block group increases progressively from the front end to the back end.

In this embodiment, the long tube 41 is a carbon fiber reinforced composite material circular tube, and the long tube 41 is as long as the long honeycomb block 21.

Carbon fiber reinforced Composites (CFRP) are composites formed using carbon fibers or carbon fiber fabrics as a reinforcement and a resin, ceramic, metal, cement, carbon, rubber, or the like as a matrix. The material has high specific strength and specific rigidity in a plurality of light-weight materials, and the light-weight effect is very obvious. However, the number of the embedded parts cannot be increased without an upper limit, and when the mass fraction of the long tube 41 exceeds a certain range, the smooth energy absorption characteristic of the long honeycomb block 21 starts to be affected.

In this embodiment, the fill tube includes a stub 42; short pipes 42 are embedded in the holes of the short honeycomb blocks 22, and the short pipes 42 in the short honeycomb blocks 22 in the same honeycomb block group are arranged in the same manner.

The short tubes 42 with the same number and the same arrangement mode can basically keep the same mechanical property, and in order to balance the stress of each honeycomb block group as much as possible, the short tubes 42 are uniformly arranged in the short honeycomb blocks 22 in the same group.

In this embodiment, in each short honeycomb block group, the number of short tubes 42 increases from the front end to the back end.

The greater the number of short tubes 42, the greater the resistance to impact forces. In order to achieve the effect of sequential compression from front to back, the number of the short tubes 42 in each short honeycomb block group is sequentially increased from the front end to the back end.

In this embodiment, the short tube 42 is an aluminum circular tube, and the short tube 42 has the same length as the short honeycomb block 22.

When all the cell elements of the honeycomb block are almost fully embedded with the aluminum circular tube, the good energy absorption characteristic of the honeycomb block can still be kept, and the energy absorption is greatly improved and can even reach ten times. However, this construction is also limited in that aluminum round tubes are susceptible to euler deformation during compression and therefore can only be used for short honeycomb blocks 22.

Preferably, the number of the long cell block groups is 6, and each long cell block group comprises 2 long cell blocks 21; the short honeycomb block group has 6 groups, and each section of honeycomb block group contains 2 short honeycomb blocks 22.

The 6 groups of long honeycomb block groups are embedded with a plurality of long pipes 41 according to the dispersion from the front to the back in sequence, the 6 groups of short honeycomb block groups are embedded with a plurality of short pipes 42 according to the dispersion from the front to the back in sequence, and the honeycomb block groups are separated by the partition plates 13, and the long pipes 41 and the short pipes 42 are different in material, so that 2 large energy level gradients which are distinguished by the long honeycomb block groups and the short honeycomb block groups are formed, and 12 small energy level gradients are distinguished due to the length difference of the long pipes 41 and the short pipes 42, thereby realizing a multistage controllable ladder energy absorption mode. Moreover, the invention can form more energy absorption modes by adjusting the arrangement scheme of the honeycomb blocks 2 and the filling pipes according to actual needs.

Preferably, the long pipe 41 is in a distributed form and the short pipe 42 is in a centrally distributed form.

The carbon fiber reinforced composite material circular tube is in disperse distribution in the honeycomb block 2 and can be coupled with more honeycomb walls, so that the carbon fiber reinforced composite material circular tube has better energy absorption performance, the aluminum circular tube is in concentrated distribution in the honeycomb block, and the deformation mode can be changed in quality, so that the carbon fiber reinforced composite material circular tube can have very large and stable energy absorption performance.

According to the invention, the embedded density and mass fraction of the filling pipes in the honeycomb blocks are controlled, so that different impact yield forces are obtained for all levels of honeycomb block groups, and the effect of sequentially absorbing energy from front to back of all levels of stairs is realized in the impact process. The invention also changes the use method that the honeycomb material is only used as the core material in the traditional energy absorption structure, further exploits the internal space of the honeycomb block 2, uses the honeycomb block 2 as the intermediate carrier, and embeds the filling tube while the thin-wall tube 1 wraps the outside, thereby realizing the controllable ladder energy absorption level in the energy absorption device. The 2 large energy level gradients respectively correspond to low-speed impact energy absorption and high-speed impact energy absorption, and a plurality of small energy level gradients are further divided in the large energy level gradients, so that the system can further adapt to different impact speeds, and the passive safety protection capability of the railway vehicle is effectively improved.

In this embodiment, the surface of the front end plate 11, which is far away from the thin-walled tube 1, is provided with the anti-climbing teeth 15, and the surface of the anti-climbing teeth 15, which is far away from the front end plate 11, is provided with a plurality of transverse tooth sockets.

When the collision happens, the anti-climbing teeth 15 of the adjacent carriages are mutually meshed, so that mutual restriction is realized, and the phenomenon of climbing can be effectively avoided.

In this embodiment, a guide groove 16 is formed at the front end opening of the thin-walled tube 1.

By providing the induction groove 16, the initial deformation of the thin-walled tube 1 at the time of impact can be effectively induced, thereby guiding the transmission of force.

Referring to fig. 7, 2 energy absorbing devices 5 are mounted at the end of the underframe structure of the car body of the rail car, and are symmetrically arranged along the center line with the underframe structure at the end.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make numerous possible variations and modifications to the present invention, or modify equivalent embodiments to equivalent variations, without departing from the scope of the invention, using the teachings disclosed above. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention should fall within the protection scope of the technical scheme of the present invention, unless the technical spirit of the present invention departs from the content of the technical scheme of the present invention.