US20210302133A1

US20210302133A1 - Intelligent moving shooting target

Info

Publication number: US20210302133A1
Application number: US17/149,768
Authority: US
Inventors: Xunrong Chen
Original assignee: Aomeiqi Electronic Technology Co Ltd
Current assignee: Aomeiqi Electronic Technology Co Ltd
Priority date: 2020-03-24
Filing date: 2021-01-15
Publication date: 2021-09-30
Also published as: CN212119007U

Abstract

An intelligent moving shooting target includes a shooting target base, a shooting target frame and a net rack. The shooting target base includes a driving base, a driven base and connecting tubes. Both ends of the connecting tubes are detachably connected with sidewalls of the driving base and the driven base. Lower ends of the driving base and the driven base are provided with wheels. A driving device is provided in the driving base. The driving device is connected with the wheels at the lower end of the driving base, and drives motion of the wheels at the lower end of the driving base. The shooting target frame is detachably mounted vertically on the shooting target base, and includes several horizontal tubes, vertical tubes, and connectors. The net rack is detachably mounted on the shooting target frame.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of Chinese Patent Application No. 202020394048.6 filed on Mar. 24, 2020, the contents of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present application relates to the field of shooting games and toys, in particular to an intelligent moving shooting target.

BACKGROUND TECHNOLOGY

Shooting games have always been children's favorite games. Toy guns, toy bows and arrows are very popular among children, and are generally used in games and sports activities. The market has many bullet-shooting toy guns, toy bows and arrows, and other shooting toys with targets to create a sense of reality, thereby making the shooting games more attractive to children. The existing shooting game targets are generally fixed targets and would not automatically move. Thus, its shooting difficulty is low and its game experience is poor. Accidental injury by a bullet that is shot out can easily occur when the target is being moved manually.
Therefore, it is necessary to provide an intelligent moving shooting target to solve the above technical problems.

SUMMARY

The present application provides an intelligent moving shooting target. A moving and detachable shooting target base, a detachable shooting target frame mounted on the shooting target base, and a detachable net rack mounted on the shooting target frame as a shooting target are used to solve the problems of the shooting target in the existing technology. Existing shooting targets are immovable, complicated in structure, occupying large space, non-detachable, inconvenience in carrying, and unreasonable in distribution of various components.
In order to solve the above technical problems, the technical scheme of the present disclosure is an intelligent moving shooting target including:

- a shooting target base, the shooting target base including a driving base, a driven base, and connecting tubes, both ends of the connecting tubes are detachably connected with sidewalls of the driving base and the driven base, lower ends of the driving base and the driven base are provided with wheels, a driving device is provided in the driving base, the driving device is connected with the wheels at the lower end of the driving base, and drives motion of the wheels at the lower end of the driving base;
- a shooting target frame having a rectangular frame structure and being detachably mounted vertically on the shooting target base, the shooting target frame including several horizontal tubes, vertical tubes, and connectors, the horizontal tubes of the frame and the vertical tubes of the frame are jointed together by the connectors for support and fixation; and
- a net rack being rectangular in shape and detachably mounted on the shooting target frame, and having a middle zone provided with a net pocket, the net pocket is used to collect an object that is shot out.

In the intelligent moving shooting target mentioned in the present application, a center and two ends of upper ends of the shooting target base are provided with first sockets, two ends of the sidewalls of the shooting target base are provided with second sockets, the shooting target frame being detachably inserted into the first sockets at corresponding positions on the driving base and the driven base, the connecting tubes being detachably inserted into the second sockets at corresponding positions on the driving base and the driven base.
In the intelligent moving shooting target mentioned in the present application, the first sockets have an inner diameter that is slightly larger than an outer diameter of the vertical tubes of the frame, projected first ribs are provided in the first sockets, the second sockets have an inner diameter that is slightly larger than an outer diameter of the connecting tubes, projected second ribs are provided in the second sockets, the first ribs are used for clamping the vertical tubes of the frame, and the second ribs are used for clamping the connecting tubes.
In the intelligent moving shooting target mentioned in the present application, the edges of the net rack are provided with connecting sleeves, and the connecting sleeves are wrapped around and connected to the shooting target frame.
In the intelligent moving shooting target mentioned in the present application, the driving device includes a drive power source mounted in the driving base for providing power source, a circuit board fixed in the driving base by screws for controlling a circuit, a motor mounted in the driving base for providing motive power, an axle provided in the driving base and connected to the wheels for driving the wheels to rotate, a gear set connected to an output end of the motor and the axle for power transmission, and a fixing frame for fixing the motor, the gear set, and the axle in the driving base.
In the intelligent moving shooting target mentioned in the present application, the driving base includes an upper housing and a base plate, the upper housing and the base plate are connected by screws, the base plate is provided with two rectangular through-holes at positions that correspond to the wheels.
In the intelligent moving shooting target mentioned in the present application, a rib plate is provided in the upper housing, the rib plate is provided with a first groove, the fixing frame is provided with a second groove, the motor is fitted in the first groove, the second groove of the fixing frame laid over the motor, and the fixing frame is fixedly connected to the upper housing by screws.
In the intelligent moving shooting target mentioned in the present application, the driving base is provided with a switch, the switch is connected to the circuit board, the switch is provided with three gear positions, including a shutdown gear and two moving gears, each of which having a different mode of motion.
In the intelligent moving shooting target mentioned in the present application, the intelligent moving shooting target includes a remote control, the driving base is provided with a receiver, the receiver is connected to the circuit board, the remote control is used to control time-delay starting and instant shutdown of the intelligent moving shooting target.
In the intelligent moving shooting target mentioned in the present application, the vertical tubes of the frame are hollow tubes disposed in a vertical direction, the horizontal tubes of the frame are hollow tubes disposed in a horizontal direction, the connectors include two-way connectors and three-way connectors; wherein the shooting target frame is divided into upper, middle and lower layers, lower ends of the vertical tubes of the frame in the lower layer are detachably mounted on the shooting target base, both ends of the horizontal tube of the frame in the lower layer are connected to upper ends of the vertical tubes of the frame in the lower layer, lower ends of the vertical tubes of the frame in the middle layer are connected to the vertical tubes of the frame in the lower layer and the horizontal tube of the frame in the lower layer by the three-way connectors, both ends of the horizontal tube of the frame in the middle layer are connected to upper ends of the vertical tubes of the frame in the middle layer, and lower ends of the vertical tubes of the frame in the upper layer are connected to the vertical tubes of the frame in the middle layer and the horizontal tube of the frame in the middle layer by the three-way connectors, both ends of the horizontal tube of the frame in the upper layer are connected to upper ends of the vertical tubes of the frame in the upper layer by the two-way connectors.
Compared with the existing technology, the beneficial effects of the present disclosure are: through the use of a moving and detachable shooting target base, a detachable shooting target frame provided on the shooting target base, and a detachable net rack provided on the shooting target frame, the intelligent moving shooting target of the present application can increase the difficulty of the shooting game and provide a good gaming experience. It is simple in structure, easy to disassemble, occupying a small space and easy to carry.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly explain the embodiment of the present disclosure or the technical scheme in the existing technology, the following is a brief description of the drawings to be used in the embodiment, and the drawings described below are only the corresponding drawings of some implementing examples of the present disclosure.

FIG. 1 is a front view of an intelligent moving shooting target of the present application.

FIG. 2 shows the structure of the intelligent moving shooting target of the present application after removal of a net rack.

FIG. 3 is a right side view of the intelligent moving shooting target of the present application.

FIG. 4 is a top view of the intelligent moving shooting target of the present application.

FIG. 5 is a left side view of a driving base of the intelligent moving shooting target of the present application.

FIG. 6 is a diagram of the structure of a first socket of the intelligent moving shooting target of the present application.

FIG. 7 is a diagram of the structure of an upper housing and a driving device of the intelligent moving shooting target of the present application.

FIG. 8 is a diagram of the structure of a base plate of the intelligent moving shooting target of the present application.

FIG. 9 is a diagram of the structure of a rib plate of the intelligent moving shooting target of the present application.

FIG. 10 is a front view of a fixing frame of the intelligent moving shooting target of the present application.

FIG. 11 is an elevated view of the fixing frame of the intelligent moving shooting target of the present application.

Among them, 1—shooting target base, 2—shooting target frame, 3—net rack, 11—driving base, 12—driven base, 13—connecting tube, 14—wheel, 15—first socket, 16—second socket, 17—switch, 18—power source box, 19—receiver, 21—vertical tube of the frame, 22—horizontal tube of the frame, 23—three—way connector, 24—two-way connector, 31—net pocket, 32—connecting sleeve, 111—upper housing, 112—base plate, 113—circuit board, 114—axle, 115—fixing frame, 116—motor, 117—gear set, 118—rib plate, 151—first rib, 1121—through hole, 1151—second groove, 1152—motor shaft opening, 1181—first groove.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following will be combined with the drawings of the embodiments of the present application, and the technical scheme of the embodiments of the present application will be described clearly and completely. It is clear that the embodiments described are only some of the embodiments of the present disclosure, and not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without making creative labour belong to the scope of protection of the present disclosure.
The directional terms mentioned in the present application, such as “upper”, “lower”, “front”, “rear”, “left”, “right”, “inside”, “outside”, “side”, “top” and “bottom”, are only references to the orientation in the drawings, and the directional terms are used to describe and understand the present disclosure, and not to limit the present disclosure.
The terms “first” and “second” in the present application are used only for descriptive purposes and cannot be understood as indicating or implying relative importance and not a restriction in the order.
In the present application, unless otherwise expressly specified and defined, the terms “connect”, “mount”, “joint” and “fix” should be interpreted broadly. For example, they may be fixedly connected, or detachably connected, or integrated. They may be mechanically connected or electrically connected. They may be directly connected or indirectly connected through an intermediary. It may be internal communication of two elements, or interaction relationship of two elements. For a person having ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific situation.
The existing shooting game targets are generally fixed targets and would not automatically move. Thus, its shooting difficulty is low and its game experience is poor. Accidental injury by a bullet that is shot out may easily occur when the target is being moved manually. The moving shooting targets in the existing technology are usually complicated in structure, occupying large space, non-detachable, and inconvenience in carrying.
The following is a preferred embodiment of an intelligent moving shooting target provided in the present application that can solve the above technical problems.
Referring to FIGS. 1, 2, 3 and 4, FIG. 1 is a front view of the intelligent moving shooting target of the present application, FIG. 2 shows the structure of the intelligent moving shooting target of the present application after removal of the net rack, FIG. 3 is a right side view of the intelligent moving shooting target of the present application, and FIG. 4 is a top view of the intelligent moving shooting target of the present application.
In the figures, elements with similar structure are represented by the same reference number.
The present application provides an intelligent moving shooting target, which includes a shooting target base 1, a shooting target frame 2, and a net rack 3.
Among them, the shooting target base 1 includes a driving base 11, a driven base 12, and connecting tubes 13. Both ends of the connecting tubes 13 can be detachably connected with the sidewalls of the driving base 11 and the driven base 12. The lower ends of the driving base 11 and the driven base 12 are provided with wheels 14. The driving base 11 is provided with a driving device. The driving device is connected with the wheels 14 at the lower end of the driving base 11, and drives the motion of the wheels 14 at the lower end of the driving base 11.
The shooting target frame 2 has a rectangular frame structure and can be detachably mounted vertically on the shooting target base 1. The shooting target frame 2 includes several horizontal tubes 22, vertical tubes 21, and connectors. The horizontal tubes 22 of the frame and the vertical tubes 21 of the frame are jointed together by the connectors for support and fixation. The vertical tubes 21 of the frame are hollow tubes disposed in a vertical direction, and the horizontal tubes 22 of the frame are hollow tubes disposed in a horizontal direction. The connectors include two-way connectors 24 and three-way connectors 23. The shooting target frame 2 is divided into upper, middle and lower layers. The lower ends of the vertical tubes 21 of the frame in the lower layer can be detachably mounted on the shooting target base 1. Both ends of the horizontal tube 22 of the frame in the lower layer are connected to the upper ends of the vertical tubes 21 of the frame in the lower layer. The lower ends of the vertical tubes 21 of the frame in the middle layer are connected to the vertical tubes 21 of the frame in the lower layer and the horizontal tube 22 of the frame in the lower layer by the three-way connectors 23. Both ends of the horizontal tube 22 of the frame in the middle layer are connected to the upper ends of the vertical tubes 21 of the frame in the middle layer, and the lower ends of the vertical tubes 21 of the frame in the upper layer are connected to the vertical tubes 21 of the frame in the middle layer and the horizontal tube 22 of the frame in the middle layer by the three-way connectors 23. Both ends of the horizontal tube 22 of the frame in the upper layer are connected to the upper ends of the vertical tubes 21 of the frame in the upper layer by the two-way connectors 24.
The net rack 3 is rectangular in shape and is detachably mounted on the shooting target frame 2. The net rack 3 has a middle zone provided with a net pocket 31. The net pocket 31 is used to collect an object that is shot out. The edges of the net rack 3 are provided with connecting sleeves 32, and the connecting sleeves 32 are wrapped around and connected to the shooting target frame 2. The connecting sleeves 32 are sleeved on the horizontal tubes 22 of the frame and the vertical tubes 21 of the frame. The connecting sleeve 32 at a shorter side of the net rack 3 is provided with a hook-and-loop fastener. When the connecting sleeve 32 with the hook-and-loop fastener is mounted at the top of a three-layer shooting target frame 2, the horizontal tube 22 of the frame in the lower layer is inserted in the connecting sleeve 32, and the vertical tubes 21 of the frame in the middle layer and the vertical tubes 21 of the frame in the upper layer are inserted in the connecting sleeves. The connecting sleeve 32 with the hook-and-loop fastener is finally installed. The hook-and-loop fastener is first unfastened, passed through the horizontal tube 22 of the frame in the upper layer, and then the hoop-and-loop fastener is fastened. Finally, the connecting sleeve 32 with the hook-and-loop fastener is connected. This facilitates a smooth installation of the net rack 3 on the shooting target frame 2.
Through the use of a moving and detachable shooting target base 1, a detachable shooting target frame 2 provided on the shooting target base 1, and a detachable net rack 3 provided on the shooting target frame 2 as a shooting target, it can increase the difficulty of the shooting game and provide a good game experience. It is simple in structure, easy to disassemble, occupying a small space and portable.
Referring to FIGS. 4, 5 and 6, FIG. 5 is a left side view of the driving base of the intelligent moving shooting target of the present application, and FIG. 6 is a diagram of the structure of the first socket of the intelligent moving shooting target of the present application.
A center and two ends of the upper ends of the shooting target base 1 are provided with first sockets 15. Two ends of the sidewalls of the shooting target base 1 are provided with second sockets 16. The shooting target frame 2 can be detachably inserted into the first sockets 15 at corresponding positions on the driving base 11 and the driven base 12. The connecting tubes 13 can be detachably inserted into the second sockets 16 at corresponding positions on the driving base 11 and the driven base 12. The first sockets 15 have an inner diameter that is slightly larger than an outer diameter of the vertical tubes 21 of the frame. Projected first ribs 151 are provided in the first sockets 15. The upper ends of the first ribs 151 are provided with barbs. The vertical tubes 21 of the frame are elastic. When the vertical tubes 21 of the frame are inserted into the first sockets 15, the vertical tubes 21 of the frame are squeezed by the first ribs 151, and slight deformation is formed so that the connection is tighter. The second sockets 16 have an inner diameter that is slightly larger than an outer diameter of the connecting tubes 13. Projected second ribs are provided in the second sockets 16. The structure of the first ribs 151 and the structure of the second ribs are similar. The first ribs 151 are used for clamping the vertical tubes 21 of the frame, and the second ribs are used for clamping the connecting tubes 13.
Referring to FIGS. 4 and 7, FIG. 7 is a diagram of the structure of the upper housing and the driving device of the intelligent moving shooting target of the present application. The driving device includes a drive power source, a circuit board 113, a motor 116, an axle 114, a gear set 117 and a fixing frame 115. A power source box 18 is mounted in the driving base 11. The drive power source can be replaceably provided in the power source box 18 for providing power source. The circuit board 113 is fixed in the driving base 11 by screws for controlling a circuit. The motor 116 is mounted in the driving base 11 for providing motive power. The axle 114 is provided in the driving base 11 and connected to the wheels 14 for driving the wheels 14 to rotate. The gear set 117 is connected to an output end of the motor 116 and the axle 114 for power transmission. The fixing frame 115 is used for fixing the motor 116, the gear set 117, and the axle 114 in the driving base 11.
Referring to FIGS. 8, 9, 10 and 11, FIG. 8 is a diagram of the structure of the base plate of the intelligent moving shooting target of the present application, FIG. 9 is a diagram of the structure of the rib plate of the intelligent moving shooting target of the present application, FIG. 10 is a front view of the fixing frame of the intelligent moving shooting target of the present application, and FIG. 11 is an elevated view of the fixing frame of the intelligent moving shooting target of the present application.
The driving base 11 includes an upper housing 111 and a base plate 112. The upper housing 111 and the base plate 112 are connected by screws. The base plate 112 is provided with two rectangular through-holes 1121 at positions that correspond to the wheels 14. A rib plate 118 is provided in the upper housing 111. The rib plate 118 is provided with a first groove 1181, and the fixing frame 115 is provided with a second groove 1151. The sidewalls of the second groove 1151 are provided with motor shaft openings 1152. The motor 116 is fitted in the first groove 1181. The second groove 1151 of the fixing frame 115 is laid over the motor 116. The output end of the motor 116 is connected with the gear set 117 in the fixing frame 115 through the motor shaft openings 1152. The fixing frame 115 is fixedly connected to the upper housing 111 by screws.
Referring to FIGS. 4 and 7, the driving base 11 is provided with a switch 17. The switch 17 is connected to the circuit board 113. The switch 17 is provided with three gear positions, including a shutdown gear and two moving gears, each of which having a different mode of motion. When the moving gear near the shutdown gear is switched on, the intelligent moving shooting target first moves a distance to the left and then automatically turns around and moves to the right, moves a distance to the right and then automatically turns around and moves to the left, and back and forth. When the moving gear far away from the shutdown gear is switched on, the intelligent moving shooting target first moves a distance to the left, pauses for a moment and then automatically turns around and moves to the right, and moves a distance to the right, pauses for a moment and then automatically turns around and moves to the left, and back and forth. The intelligent moving shooting target includes a remote control. The driving base 11 is provided with a receiver 19. The receiver 19 is connected to the circuit board 113. The remote control is used to control time-delay starting and instant shutdown of the intelligent moving shooting target.
The working principle of the present disclosure is that the connecting tubes 13 are inserted into the second sockets 16 on the sidewalls of the driving base 11 and the driven base 12. The vertical tubes 21 of the frame in the lower layer are inserted into the first sockets 15 at corresponding positions on the driving base 11 and the driven base 12. The horizontal tube 22 of the frame in the lower layer is passed through the connecting sleeve 32 at the lower end of the net rack 3. The two ends of the horizontal tube 22 of the frame in the lower layer are connected with the upper ends of the vertical tubes 21 of the frame in the lower layer through the three-way connectors 23. The vertical tubes 21 of the frame in the middle layer are inserted into the connecting sleeves 32 on two sides of the net rack 3. The vertical tubes 21 of the frame in the middle layer are connected with the horizontal tube 22 of the frame in the lower layer and the vertical tubes 21 of the frame in the lower layer through the three-way connectors 23. The two ends of the horizontal tube 22 of the frame in the middle layer are connected with the upper ends of the vertical tubes 21 of the frame in the middle layer through the three-way connectors 23. The vertical tubes 21 of the frame in the upper layer are inserted into the connecting sleeves 32 on the two sides of the net rack 3. The lower ends of the vertical tubes 21 of the frame in the upper layer are connected with the horizontal tube 22 of the frame in the middle layer and the upper ends of the vertical tubes 21 of the frame in the middle layer through the three-way connectors 23. The horizontal tube 22 of the frame in the upper layer is connected with the upper ends of the vertical tubes 21 of the frame in the upper layer through the two-way connectors 24. A hook-and-loop fastener of the connecting sleeve 32 at the upper end of the net rack 3 is unfastened, passed through the horizontal tube 22 of the frame in the upper layer, and then the hoop-and-loop fastener is fastened.
When the switch on the driving base 11 is switched to the moving gears, the intelligent moving shooting target starts to move. The remote control is used to control time-delay starting and instant shutdown of the intelligent moving shooting target.
In this way, the assembly and working process of a preferred embodiment of the intelligent moving shooting target is completed.
In summary, although a preferred embodiment of the present disclosure has been disclosed above, the above-mentioned preferred embodiment is not used to limit the present disclosure. A person having ordinary skill in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Hence, the scope of protection of the present disclosure is defined according to the claims.

Claims

What is claimed is:

1. An intelligent moving shooting target, comprising:

a shooting target base, the shooting target base comprising a driving base, a driven base and connecting tubes, wherein both ends of the connecting tubes are detachably connected with sidewalls of the driving base and the driven base, lower ends of the driving base and the driven base are provided with wheels, a driving device is provided in the driving base, the driving device is connected with the wheels at the lower end of the driving base and drives motion of the wheels at the lower end of the driving base;

a shooting target frame having a rectangular frame structure and being detachably mounted vertically on the shooting target base, the shooting target frame comprising several horizontal tubes, vertical tubes, and connectors, the horizontal tubes of the frame and the vertical tubes of the frame are jointed together by the connectors for support and fixation; and

a net rack being rectangular in shape and detachably mounted on the shooting target frame, and having a middle zone provided with a net pocket, the net pocket being used to collect an object that is shot out.

2. The intelligent moving shooting target according to claim 1, wherein a center and two ends of upper ends of the shooting target base are provided with first sockets, two ends of the sidewalls of the shooting target base are provided with second sockets, the shooting target frame being detachably inserted into the first sockets at corresponding positions on the driving base and the driven base, the connecting tubes being detachably inserted into the second sockets at corresponding positions on the driving base and the driven base.

3. The intelligent moving shooting target according to claim 2, wherein the first sockets have an inner diameter that is slightly larger than an outer diameter of the vertical tubes of the frame, projected first ribs are provided in the first sockets, the second sockets have an inner diameter that is slightly larger than an outer diameter of the connecting tubes, projected second ribs are provided in the second sockets, the first ribs are used for clamping the vertical tubes of the frame, and the second ribs are used for clamping the connecting tubes.

4. The intelligent moving shooting target according to claim 1, wherein edges of the net rack are provided with connecting sleeves, and the connecting sleeves are wrapped around and connected to the shooting target frame.

5. The intelligent moving shooting target according to claim 1, wherein the driving device comprises:

a drive power source mounted in the driving base for providing power source;

a circuit board fixed in the driving base by screws for controlling a circuit;

a motor mounted in the driving base for providing motive power;

an axle provided in the driving base and connected to the wheels for driving the wheels to rotate;

a gear set connected to an output end of the motor and the axle for power transmission; and

a fixing frame for fixing the motor, the gear set, and the axle in the driving base.

6. The intelligent moving shooting target according to claim 5, wherein the driving base comprises an upper housing and a base plate, the upper housing and the base plate are connected by screws, the base plate is provided with two rectangular through-holes at positions that correspond to the wheels.

7. The intelligent moving shooting target according to claim 6, wherein a rib plate is provided in the upper housing, the rib plate is provided with a first groove, the fixing frame is provided with a second groove, the motor is fitted in the first groove, the second groove of the fixing frame laid over the motor, and the fixing frame is fixedly connected to the upper housing by screws.

8. The intelligent moving shooting target according to claim 5, wherein the driving base is provided with a switch, the switch is connected to the circuit board, the switch is provided with three gear positions, including a shutdown gear and two moving gears, each of which having a different mode of motion.

9. The intelligent moving shooting target according to claim 5, wherein the intelligent moving shooting target comprises a remote control, the driving base is provided with a receiver, the receiver is connected to the circuit board, the remote control is used to control time-delay starting and instant shutdown of the intelligent moving shooting target.

10. The intelligent moving shooting target according to claim 1, wherein the vertical tubes of the frame are hollow tubes disposed in a vertical direction, the horizontal tubes of the frame are hollow tubes disposed in a horizontal direction, the connectors include two-way connectors and three-way connectors;

wherein the shooting target frame is divided into upper, middle and lower layers, lower ends of the vertical tubes of the frame in the lower layer are detachably mounted on the shooting target base, both ends of the horizontal tube of the frame in the lower layer are connected to upper ends of the vertical tubes of the frame in the lower layer, lower ends of the vertical tubes of the frame in the middle layer are connected to the vertical tubes of the frame in the lower layer and the horizontal tube of the frame in the lower layer by the three-way connectors, both ends of the horizontal tube of the frame in the middle layer are connected to upper ends of the vertical tubes of the frame in the middle layer, and lower ends of the vertical tubes of the frame in the upper layer are connected to the vertical tubes of the frame in the middle layer and the horizontal tube of the frame in the middle layer by the three-way connectors, and both ends of the horizontal tube of the frame in the upper layer are connected to upper ends of the vertical tubes of the frame in the upper layer by the two-way connectors.