An integrated folding container structure and door structure and body structure thereof

Abstract

An integrated folding container structure, a door structure and a box structure thereof, comprising door frames arranged at both ends of the box, a connecting rod mechanism connecting the two door frames and a door body mounted on the inner side of the door frame; a top beam, a top column, a vertical column, a bottom column and a bottom beam arranged from top to bottom together form a square door frame, and two pairs of left and right opening top doors, middle doors and bottom doors are sequentially mounted on the inner side of the door frame from top to bottom; the two ends of the vertical column and the bottom column are hingedly arranged, so that the door body can be folded after each part is rotated into the box body; the overall height of the empty container after folding is about one third of that in the unfolded state, which is convenient for storage and can reduce storage costs, and can also facilitate the transportation of more empty containers by ships to reduce transportation costs, and can also improve the wind resistance of the empty container and reduce the safety risk.

Description

TECHNICAL FIELD

[0001] The present application relates to a container for freight transportation, in particular to a folding container structure, and a door structure and a body structure of the integrated folding container. BACKGROUND

[0002] A container is a commonly used freight transportation tool, which is a cuboid structure and has openable doors at one or both ends of the cuboid. The existing containers are generally fixed structures, and multiple containers are stacked together in use to improve the loading capacity of the transportation equipment (such as a ship). However, when the transportation equipment returns after transporting goods to the destination, the containers are often in an empty state, resulting in a cost close to that of the delivery process, and also severely limiting the loading capacity of the transportation equipment. In addition, the containers still occupy the same storage space after unloading the goods, which also affects the storage capacity of the freight yard. Furthermore, the empty containers have poor wind resistance in the storage state, and there is a high safety hazard in typhoon weather.

[0003] At present, in order to reduce the storage and transportation cost of the empty container, some foldable containers have appeared, but the folding degree of the existing foldable containers is low, and the folded container still needs to occupy a large amount of space, which cannot effectively reduce the storage and transportation cost. SUMMARY

[0004] The purpose of the present application is to provide an integrated folding container structure with high folding degree and convenient operation, and a door structure and a body structure of the integrated folding container.

[0005] The door structure of the integrated folding container of the present application comprises door frames arranged at both ends of the container body, and door bodies installed on the inner side of the door frames. The door frame comprises a top beam and a bottom beam arranged opposite to each other and horizontally, a top column, a vertical column and a bottom column vertically arranged between the two ends of the top beam and the bottom beam, the top end of the top column is fixedly installed at the bottom of the top beam, the bottom end of the bottom column is hingedly connected with the end of the bottom beam, and the two ends of the vertical column are hingedly connected with the top column and the bottom column respectively. The door body comprises a top door, a middle door and a bottom door respectively installed on the top column, the vertical column and the bottom column, the horizontal height of the bottom of the middle door is higher than the hinged end of the vertical column and the bottom column, the horizontal height of the top of the bottom door is lower than the hinged end of the vertical column and the bottom column, and a liftable door bar is further installed on the bottom door.

[0006] The integrated folding container box structure comprises door frames arranged at two ends respectively, and a connecting rod mechanism connecting the two door frames; the door frame comprises a top beam and a bottom beam arranged opposite and horizontally, and a top column, a vertical column and a bottom column arranged vertically between the two ends of the top beam and the bottom beam, the top end of the top column is fixedly installed at the bottom of the top beam, the bottom end of the bottom column is hingedly connected with the end of the bottom beam, and the two ends of the vertical column are hingedly connected with the top column and the bottom column respectively; the connecting rod mechanism comprises a top rod connected between the ends of the top beam, a bottom rod connected between the ends of the bottom beam, and an upper support rod, a vertical column support rod and a lower support rod connected between the hingedly connected ends of the top column and the vertical column, the hingedly connected ends of the vertical column and the bottom column, and the hingedly connected ends of the bottom column and the bottom beam respectively.

[0007] The integrated folding container box structure comprises door frames arranged at two ends respectively, and a connecting rod mechanism connecting the two door frames; the door frame comprises a top beam and a bottom beam arranged opposite and horizontally, and a top column, a vertical column and a bottom column arranged vertically between the two ends of the top beam and the bottom beam, the top end of the top column is fixedly installed at the bottom of the top beam, the bottom end of the bottom column is hingedly connected with the end of the bottom beam, and the two ends of the vertical column are hingedly connected with the top column and the bottom column respectively; the connecting rod mechanism comprises a top rod connected between the ends of the top beam, a bottom rod connected between the ends of the bottom beam, and an upper support rod, a vertical column support rod and a lower support rod connected between the hingedly connected ends of the top column and the vertical column, the hingedly connected ends of the vertical column and the bottom column, and the hingedly connected ends of the bottom column and the bottom beam respectively.

[0008] The integrated folding container box structure comprises door frames arranged at two ends respectively, and a connecting rod mechanism connecting the two door frames; the door frame comprises a top beam and a bottom beam arranged opposite and horizontally, and a top column, a vertical column and a bottom column arranged vertically between the two ends of the top beam and the bottom beam, the top end of the top column is fixedly installed at the bottom of the top beam, the bottom end of the bottom column is hingedly connected with the end of the bottom beam, and the two ends of the vertical column are hingedly connected with the top column and the bottom column respectively; the connecting rod mechanism comprises a top rod connected between the ends of the top beam, a bottom rod connected between the ends of the bottom beam, and an upper support rod, a vertical column support rod and a lower support rod connected between the hingedly connected ends of the top column and the vertical column, the hingedly connected ends of the vertical column and the bottom column, and the hingedly connected ends of the bottom column and the bottom beam respectively.

[0009] The integrated folding container structure, the door structure and the box structure thereof, the top beam, the top column, the vertical column, the bottom column and the bottom beam arranged from top to bottom jointly form a square door frame, two pairs of left and right opposite top doors, middle doors and bottom doors are sequentially arranged from top to bottom on the inner side of the door frame, and a gap is left between the middle door and the bottom door, the door bar installed on the bottom door can shield the gap after being moved up to contact with the middle door, and the gap can be exposed again after the door bar is retracted into the bottom door. When the container needs to be folded, the container is lifted by lifting equipment (such as a crane), then the door bar is retracted into the bottom door to expose the gap between the middle door and the bottom door, thereby providing space for subsequent folding operation; then, the top door, the middle door and the bottom door are rotated around the top column, the vertical column and the bottom column respectively and are turned inwards to the inner wall of the container body for locking; then, the top column, the vertical column and the bottom column are rotated inwards around the mutual hinge ends thereof until the vertical column is rotated to a parallel state, thereby completing the folding of the door frame and the door body; at the same time, the upper support rod, the vertical column support rod and the lower support rod of the box structure are also rotated and folded, thereby completing the folding of the entire container; when the container needs to be unfolded, the reverse operation is performed until the top door, the middle door and the bottom door are closed again, and the gap between the middle door and the bottom door is shielded by the door bar; in addition, the top door can remain unrotated into the box body and remain in a closed state, so that the folded container can also remain in a closed state.

[0010] In the integrated folding container door structure, the inner side of the top beam and the top column fixedly installed thereon corresponds to the top space of the container, which can be used for the top door and also provides a space for the lower components to flow out when folded; the appropriate gap left between the middle door and the bottom door can ensure the space requirement of the folding operation of the vertical column and the bottom column, and can shield the gap by the door bar when the container is unfolded, so as to ensure the integrity of the door body and meet the use requirement; the arrangement of the six pairs of opposite doors improves the problems of large volume, large weight and inability to fold of a single door body. The integrated folding container with the door structure and the box structure can fold the overall height of the empty container to about one third of the unfolded state, greatly improves the folding degree of the container, reduces the storage cost, facilitates the transportation of more empty containers by ships, reduces the transportation cost, improves the wind resistance of the empty container and reduces the safety risk. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 、 2 is a structural schematic view of the integrated folding container door structure.

[0012] Figure 3 is a structural schematic view of the middle door and the upper door groove thereof.

[0013] Figure 4、 5 Fig. 4 is a structural diagram of the lock and the upper and lower locking grooves.

[0014] Figure 6 Fig. 5 is a structural diagram of the connection between the door frame and the door body.

[0015] Figures 7-9 Figs. 6 and 7 are structural diagrams of the door body rotating to different positions relative to the door frame.

[0016] Figure 10 Fig. 8 is a structural diagram of an integrated folding container body structure.

[0017] Figure 11 Fig. 9 is a partial structural diagram of the integrated folding container body structure. DETAILED DESCRIPTION

[0018] An integrated folding container door structure comprises door frames arranged at both ends of a container body and door bodies installed on the inner sides of the door frames. The door frame comprises a top beam 11 and a bottom beam 12 arranged opposite to each other and horizontally, and a top column 13, a vertical column 14 and a bottom column 15 arranged vertically between both ends of the top beam and the bottom beam. The top end of the top column is fixedly installed on the bottom of the top beam, the bottom end of the bottom column is hingedly connected with the end of the bottom beam, and both ends of the vertical column are hingedly connected with the top column and the bottom column, respectively. The door body comprises a top door 21, a middle door 22 and a bottom door 23 installed on the top column, the vertical column and the bottom column, respectively, and the horizontal height of the bottom of the middle door is higher than the hinged end of the vertical column and the bottom column, the horizontal height of the top of the bottom door is lower than the hinged end of the vertical column and the bottom column, and a liftable door bar 24 is further installed on the bottom door.

[0019] The top beam, the top column, the vertical column, the bottom column and the bottom beam from top to bottom together form a square door frame, and two pairs of left and right opening top doors, middle doors and bottom doors are sequentially installed inside the door frame from top to bottom, and a gap is left between the middle door and the bottom door, and the door bar installed on the bottom door can block the gap after moving up to contact the middle door, and the door bar can also expose the gap again after being retracted into the bottom door. When the container needs to be folded, the container is lifted by lifting equipment, then the door bar is retracted into the bottom door to expose the gap between the middle door and the bottom door, thereby providing space for subsequent folding operation; then, the top door, the middle door and the bottom door are respectively rotated around the top column, the vertical column and the bottom column and turned inward to the inner wall of the container body for locking; then, the top column, the vertical column and the bottom column are rotated inward around their mutually hinged ends until the vertical column is rotated to a parallel state, thereby completing the folding of the door frame and the door body; in addition, the top door can also remain unrotated into the container body and remain in a closed state, so that the folded container can also remain in a closed state; when the container needs to be unfolded, the reverse operation is performed and finally the gap is blocked by the door bar, so that the top door, the middle door, the door bar and the bottom door together form a complete door body to block the door hole on the door frame. In the integrated folding container door structure, the inner side of the top beam and the top column fixedly installed thereon corresponds to the top space of the container, which can be used for the top door and also provides space for the lower parts to flow out when folded; the appropriate gap left between the middle door and the bottom door can ensure the space requirement of the vertical column and the bottom column folding operation, and when the container is unfolded, the door bar can be used to block the gap to ensure the integrity of the door body and meet the use requirement; the arrangement of six pairs of opening doors improves the problems of large size, heavy weight and inability to fold of a single door body.

[0020] The integral folding container door structure is provided with a lifting opening 16 on the top beam 11 for connecting a lifting device, so that the lifting device can lift the container, thereby facilitating folding or unfolding of the container. The door bolt mechanism includes a top door bolt 31 mounted on the door post for fixing the top door on the top beam 11, a middle door bolt 32 for fixing the middle door on the top door, a bottom door bolt 33 for fixing the bottom door on the bottom beam, a door post locking bolt 34 for lifting and fixing the door post on the bottom column 15, a door post connecting bolt 35 for connecting two door posts, and a door post positioning bolt 36 for fixing the door post 24 and the middle door 22. In addition, the side plate of the bottom of the middle door 22 towards the door post 24 is provided with a door groove 25 for inserting the top of the door post. The door body is fixed by the door bolt mechanism. When the container door needs to be folded, the door post locking bolt and the door post connecting bolt are released, the door post is lowered and folded into the bottom door, the middle door bolt and the bottom door bolt are opened to make the middle door and the bottom door rotate into the container, then the top door bolt is opened to make the top door rotate into the container, and the door body and the container can be folded. When the container is unfolded and the door body needs to be locked, the top door and the bottom door are fixed on the top beam and the bottom beam by the top door bolt and the bottom door bolt, the middle door is fixed by the middle door bolt, the door post is lifted and inserted into the door groove of the middle door, the door post is fixed by the door post locking bolt, and the two door posts are fixed by the door post connecting bolt. When the door post is lifted, the door post and the middle door can be fixed by the door post positioning bolt for preliminary positioning and fixing, thereby improving the positioning accuracy and the stability of the closed door body.

[0021] As shown in Figure 4 、 5 , the outer bottom of the top column 13 is hinged with a lock catch 41, the end of the lock catch is provided with a lock hook 42, the outer top of the upright column 14 and the outer side of the end of the bottom beam 12 are respectively provided with an upper lock slot 43 and a lower lock slot 44 for inserting and fixing the lock hook. As shown in Figure 4 、 5 , after the container is folded and the door body is rotated into the container, the lock catch is rotated to make the lock hook disengage from the upper lock slot, and the upright column can be folded. After folding is completed, the lock catch is rotated to make the lock hook inserted into the lower lock slot, thereby locking the folded state. When the folded container is unfolded, the lock hook of the lock catch is inserted into the upper lock slot, the top column and the upright column are fixed, thereby making the container more stably unfolded.

[0022] As shown in Figure 6As shown, the cross-sectional shape of the top post 13, the vertical post 14 and the bottom post 15 at the hinged end between the top door 21, the middle door 22 and the bottom door 23 is rectangular, and the center of the rectangle is provided with a hinge post 51, and a stop block 52 is arranged between the hinge post and the side of the top post, the vertical post or the bottom post facing the inside of the container body, and the side of the top post, the vertical post or the bottom post away from the inside of the container body extends to the stop block to form a hinge groove 53; the hinge plate 54 is fixedly arranged on the top door, the middle door and the bottom door; and the hinge block 55 is arranged, and the two ends of the hinge block are respectively hinged to the hinge post and the hinge plate; thus, the hinge plate and the hinge block form more diversified degrees of freedom of the hinge, so that the top door, the middle door or the bottom door can be conveniently hidden inside the top post, the vertical post or the bottom post when the container is folded, and the door body can also be opened outward when the container is unfolded, so as to facilitate the carrying of goods. Specifically, the cross-sectional shape of the stop block 52 is triangular, one corner of the triangle is connected with the hinge post 51, the other corner has a gap between the opposite sides of the two top posts / two vertical posts / two bottom posts, and the remaining corner is arranged at the end of the opposite sides of the two top posts / two vertical posts / two bottom posts and extends to the side of the top post / vertical post / bottom post away from the inside of the container body by a certain length, and the extending end is arranged between the hinge post and the side of the top post / vertical post / bottom post facing the inside of the container body; and the cross-sectional shape of the hinge block 55 is "7" shape, and the two ends of the "7" shape are respectively hinged to the hinge post and the hinge plate 54, and the inner side of the "7" shape of the hinge block is matched with the corner of the triangular stop block facing the inside of the door frame. As shown in Figure 7 the inner side of the "7" shape of the hinge block is matched with one corner of the stop block, and the hinge plate is parallel to the inside of the door frame, so that the door body is in the closed position; when the door body needs to be folded, the door body is rotated to the inside of the container as shown in Figure 8 the hinge plate faces the inside of the container, and the door body is hidden by the door frame; and when the container is used normally and the door body needs to be opened, the door body is rotated to the outside of the container as shown in Figure 9 so that the door body is matched to the outer wall of the container, so as not to affect the carrying of goods and avoid colliding with personnel or equipment. Thus, the top door, the middle door or the bottom door can be extremely conveniently and accurately hidden inside the top post, the vertical post or the bottom post, so as to ensure the accuracy and convenience of the folding of the container.

[0023] The application relates to a one-piece folding container body structure, which comprises door frames arranged at two ends respectively, and a connecting rod mechanism connecting the two door frames; the door frame comprises a top beam 11 and a bottom beam 12 arranged horizontally and oppositely, and a top column 13, a vertical column 14 and a bottom column 15 arranged vertically between the two ends of the top beam and the bottom beam; the top end of the top column is fixedly arranged at the bottom of the top beam, the bottom end of the bottom column is hingedly connected with the end of the bottom beam, and the two ends of the vertical column are hingedly connected with the top column and the bottom column respectively; the connecting rod mechanism comprises a top rod 61 connected between the ends of the top beam, a bottom rod 62 connected between the ends of the bottom beam, and an upper supporting rod 63, a vertical column supporting rod 64 and a lower supporting rod 65 connected between the hinged ends of the top column and the vertical column, the hinged ends of the vertical column and the bottom column and the hinged ends of the bottom column and the bottom beam respectively; in addition, a top plate and a bottom plate are arranged between the two top rods 61 and the two bottom rods 62 respectively, and an outer plate (not shown) is arranged between the top rod and the upper supporting rod 63, the upper supporting rod and the vertical column supporting rod 64 and the vertical column supporting rod and the lower supporting rod 65 respectively.

[0024] The one-piece folding container body structure connects the door frames at two ends through the top rod, the bottom rod, the upper supporting rod, the vertical column supporting rod and the lower supporting rod, and the main frame of the container body is formed, and then the outer plate is arranged on the frame as the wall of the container, so that the structure is simple and the folding can be effectively matched with the door structure.

[0025] The one-piece folding container body structure is provided with a rotating shaft 7 at the hinged end between the top column 13, the vertical column 14 and the bottom column 15, one end of the rotating shaft penetrates through the hinged end and is connected with the upper supporting rod 63, the vertical column supporting rod 64 or the lower supporting rod 65, so that each rod body rotates with the folding operation, thereby improving the folding convenience and accuracy.

[0026] The application relates to a one-piece folding container structure, which comprises door frames arranged at two ends of a container body respectively, a connecting rod mechanism connecting the two door frames, and a door body arranged on the inner side of the door frame; the door frame comprises a top beam 11 and a bottom beam 12 arranged horizontally and oppositely, and a top column 13, a vertical column 14 and a bottom column 15 arranged vertically between the two ends of the top beam and the bottom beam; the top end of the top column is fixedly arranged at the bottom of the top beam, the bottom end of the bottom column is hingedly connected with the end of the bottom beam, and the two ends of the vertical column are hingedly connected with the top column and the bottom column respectively; the door body comprises a top door 21, a middle door 22 and a bottom door 23 arranged on the top column, the vertical column and the bottom column respectively, the horizontal height of the bottom of the middle door is higher than the hinged end of the vertical column and the bottom column, the horizontal height of the top of the bottom door is lower than the hinged end of the vertical column and the bottom column, and a liftable door bar 24 is arranged on the bottom door; the connecting rod mechanism comprises a top rod 61 connected between the ends of the top beam, a bottom rod 62 connected between the ends of the bottom beam, and an upper supporting rod 63, a vertical column supporting rod 64 and a lower supporting rod 65 connected between the hinged ends of the top column and the vertical column, the hinged ends of the vertical column and the bottom column and the hinged ends of the bottom column and the bottom beam respectively.

[0027] The integrated folding container structure can fold the door body to the inside of the box body, and then fold the door frame and the box body, so that the overall height of the empty container can be folded to about one third of the unfolded state, greatly improving the folding degree of the container, facilitating storage and reducing storage costs, facilitating the transportation of more empty containers by ships to reduce transportation costs, and improving the wind resistance of the empty container and reducing safety risks.

Claims

1. An integrated folding container door structure, comprising door frames arranged at both ends of a container body, and a door body installed on the inner side of the door frames; characterized in that: The door frame comprises upper and lower opposite and transversely arranged top beam (11) and bottom beam (12), top beam and bottom beam are vertically arranged between two ends of top post (13), stand (14) and bottom post (15) respectively, the top end of top post is fixedly installed on the bottom of top beam, the bottom end of bottom post is hinged with the end of bottom beam, the two ends of stand are respectively hinged with top post and bottom post; The door body comprises top door (21), middle door (22) and bottom door (23) respectively installed on top post, stand and bottom post, and the horizontal height of the bottom of middle door is higher than the hinge end of stand and bottom post, the horizontal height of the top of bottom door is lower than the hinge end of stand and bottom post, and the bottom door is further provided with a liftable door bar (24); The gap is left between the middle door and the bottom door, the door bar is lifted to contact with the middle door and block the gap, and the door bar is lowered into the bottom door and exposes the gap.

2. The one-piece folding shipping container door structure of claim 1, wherein: There are door bolt mechanisms for fixing top door (21), middle door (22), bottom door (23) and door bar (24) respectively; It comprises top door bolt (31) installed on door bar for fixing top door on top beam (11), middle door bolt (32) for fixing middle door on top door, bottom door bolt (33) for fixing bottom door on bottom beam, and door bar locking bolt (34) for lifting and fixing door bar (24) on bottom post (15).

3. The one-piece folding shipping container door structure of claim 2, wherein: There are door bar connecting bolts (35) connecting two door bars, and door bar positioning bolts (36) fixing door bar (24) and middle door (22) to each other.

4. The one-piece folding shipping container door structure of claim 1, wherein: The side plate of the bottom of middle door (22) towards door bar (24) is provided with door slot (25) for inserting the top of door bar.

5. The one-piece folding shipping container door structure of claim 1, wherein: The outer side bottom of top post (13) is hinged with lock catch (41), the end of lock catch is provided with lock hook (42), the outer side top of stand (14) and the outer side of the end of bottom beam (12) are respectively provided with upper lock slot (43) and lower lock slot (44) for inserting and fixing lock hook.

6. The one-piece folding shipping container door structure of claim 1, wherein: The cross-sectional shape of top post (13), stand (14) and bottom post (15) is rectangular at the hinge end between top door (21), middle door (22) and bottom door (23), the center of the rectangle is provided with hinge post (51), the hinge post and the side of top post, stand or bottom post towards the inside of container body are provided with stop block (52), the side of top post, stand or bottom post away from the inside of container body extends to the stop block to form empty hinge slot (53); Top door, middle door and bottom door are fixedly installed with hinge plate (54); There are hinge blocks (55), the two ends of hinge block are respectively hinged with hinge post and hinge plate.

7. The one-piece folding shipping container door structure of claim 6, wherein: The cross-sectional shape of stop block (52) is triangular, one angle of the triangle is connected with hinge post (51), the other angle leaves a gap between the opposite sides of two top posts / two stands / two bottom posts, and the remaining angle is arranged at the end of the opposite side of two top posts / two stands / two bottom posts and extends to the side of top post / stand / bottom post away from the inside of container body for a certain length; The cross-sectional shape of hinge block (55) is "7" shape, the two ends of "7" shape are respectively hinged with hinge post and hinge plate (54), and the inside of "7" shape of hinge block is matched with the angle of triangular stop block towards the inside of door frame.

8. The one-piece folding container door structure according to any one of claims 1-7, installed on a one-piece folding container body structure, the one-piece folding container body structure comprising door frames respectively arranged at two ends, and a connecting link mechanism connecting the two door frames, characterized in that: The door frame comprises upper and lower top beams (11) and bottom beams (12) arranged transversely, top posts (13), vertical posts (14) and bottom posts (15) arranged vertically between the two ends of the top beams and the bottom beams, the top ends of the top posts are fixedly installed at the bottom of the top beams, the bottom ends of the bottom posts are hingedly connected with the end portions of the bottom beams, the two ends of the vertical posts are hingedly connected with the top posts and the bottom posts respectively; the connecting rod mechanism comprises top rods (61) connected between the end portions of the top beams, bottom rods (62) connected between the end portions of the bottom beams, and upper support rods (63), vertical support rods (64) and lower support rods (65) connected between the hingedly connected ends of the top posts and the vertical posts, the hingedly connected ends of the vertical posts and the bottom posts and the hingedly connected ends of the bottom posts and the bottom beams respectively.

9. The one-piece folding shipping container door structure of claim 8, wherein: A rotating shaft (7) is arranged at the hingedly connected end between the top post (13), the vertical post (14) and the bottom post (15), one end of the rotating shaft penetrates through the hingedly connected end and is connected with the upper support rod (63), the vertical support rod (64) or the lower support rod (65).

10. An integrated folding container structure comprising door frames arranged at both ends of a box body, a connecting rod mechanism connecting the two door frames, and door bodies installed on the inner sides of the door frames, characterized in that: The door frame comprises upper and lower top beams (11) and bottom beams (12) arranged transversely, top posts (13), vertical posts (14) and bottom posts (15) arranged vertically between the two ends of the top beams and the bottom beams, the top ends of the top posts are fixedly installed at the bottom of the top beams, the bottom ends of the bottom posts are hingedly connected with the end portions of the bottom beams, the two ends of the vertical posts are hingedly connected with the top posts and the bottom posts respectively; the door body comprises top doors (21), middle doors (22) and bottom doors (23) installed on the top posts, the vertical posts and the bottom posts respectively, the horizontal height of the bottom portion of the middle doors is higher than the hingedly connected ends of the vertical posts and the bottom posts, the horizontal height of the top portion of the bottom doors is lower than the hingedly connected ends of the vertical posts and the bottom posts, and a liftable door bar (24) is further installed on the bottom doors; a gap is left between the middle doors and the bottom doors, the door bar is lifted to contact the middle doors and shield the gap, and the door bar is lowered into the bottom doors and exposes the gap; the connecting rod mechanism comprises top rods (61) connected between the end portions of the top beams, bottom rods (62) connected between the end portions of the bottom beams, and upper support rods (63), vertical support rods (64) and lower support rods (65) connected between the hingedly connected ends of the top posts and the vertical posts, the hingedly connected ends of the vertical posts and the bottom posts and the hingedly connected ends of the bottom posts and the bottom beams respectively.

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