Modular low-drag, towed van and method of use

Abstract

The application discloses a modular low-wind-resistance trailer van and a use method, and belongs to the technical field of trailers, which comprises a left surrounding assembly and a right surrounding assembly, a front protruding surrounding assembly installed at the front ends of the left surrounding assembly and the right surrounding assembly, and a tail door assembly installed at the rear ends of the left surrounding assembly and the right surrounding assembly. Lower ends of the left surrounding assembly and the right surrounding assembly are provided with bottom frame crossbeams, and upper ends are provided with roof crossbeams. The tail door assembly is composed of an outer frame, a split frame and a lower opening door arranged from outside to inside in sequence. The outer frame and the split frame are hinged through side portions, and the split frame and the lower opening door are hinged through lower portions. A bolt lock assembly is arranged in the lower opening door. An internal split locking assembly is arranged in the split frame, and the split locking assembly is interlocked with the bolt lock assembly. The application solves the problems of large wind resistance coefficient, large maintenance difficulty and single opening mode of the tail door of the existing trailer van.

Description

Technical Field

[0001] This invention belongs to the field of trailer technology, specifically relating to a modular, low-drag towable van and its usage method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Trailer-mounted box trailers, with their large loading capacity and flexible use, have become essential equipment in logistics transportation and special cargo transshipment. Currently, the trailer body structure of these trailers mainly relies on two traditional manufacturing processes: one is a rigid frame structure welded from large steel beams, and the other is an integrated body formed by integral molding using composite materials such as fiberglass. However, the front end of these bodies often adopts a flat or slightly curved transition, resulting in a high drag coefficient, which is detrimental to energy conservation and emission reduction. When partial damage occurs to the body, the existing structure needs to be cut, welded, or completely replaced, making repair processes complex and difficult, affecting vehicle uptime and service life. Furthermore, the tailgate structure of existing trailer-mounted trailers has a single function, supporting only a limited number of opening or usage modes, making it difficult to adapt to diverse loading and unloading needs in different scenarios, resulting in extremely low applicability and efficiency in complex operating environments. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a modular, low-drag towable van and its usage method, solving the issues of high drag coefficient, difficult maintenance, and limited tailgate opening methods in existing vans.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a modular low-drag towable van, comprising: an A-type towing frame, a front convex assembly, a left convex assembly, a right convex assembly, and a tailgate assembly; the front convex assembly is generally U-shaped with its pointed corners facing forward and is installed at the front end of the left convex assembly and the right convex assembly; the tailgate assembly is installed at the rear end of the left convex assembly and the right convex assembly; a bottom frame crossbeam is provided at the lower end of the left convex assembly and the right convex assembly, and a roof crossbeam is provided at the upper end of the left convex assembly and the right convex assembly;

[0007] The tailgate assembly consists of an outer frame, a split frame, and a bottom door arranged sequentially from the outside in. The outer frame and the split frame are hinged at the sides, and the split frame and the bottom door are hinged at the bottom. A bolt lock assembly is installed in the bottom door. An upper bolt and a lower bolt are respectively provided on both sides of the drive gear of the bolt lock assembly. The upper bolt passes through the split upper hole on the split frame and is inserted into the fixed upper hole on the outer frame. The lower bolt passes through the split lower hole on the split frame and is inserted into the fixed lower hole on the outer frame. A split locking assembly is provided inside the split frame, and the split locking assembly is interlocked with the bolt lock assembly.

[0008] As a further implementation, the split locking assembly is disposed on one side of the split lower hole. The split locking assembly consists of a hinge shaft, a Z-shaped lever, a torsion spring, and a locking pin. The Z-shaped lever is mounted on the split frame via the hinge shaft. The torsion spring is disposed between the Z-shaped lever and the split frame. One end of the Z-shaped lever is provided with a locking pin, and the other end is provided with a driving part. When the lower pin is fully withdrawn from the split lower hole, the driving part abuts against the end of the lower pin, and the locking pin is inserted into the locking hole provided on the split frame and the outer frame under the action of the torsion spring. After the lower pin is inserted into the split lower hole, the driving part abuts against the side of the lower pin, and the locking pin is withdrawn from the locking hole under the action of the lower pin.

[0009] As a further implementation, a rack is provided at the end of the upper and lower pins near the drive gear, and the rack meshes with the drive gear.

[0010] As a further implementation, the left and right side assemblies are respectively constructed from slender square tubes riveted together to form a planar frame; the A-type traction frame is constructed from square tubes welded into a triangular load-bearing frame; and the bottom frame beam and roof beam are slender square tube structures.

[0011] As a further implementation, the front bulkhead assembly, left bulkhead assembly, right bulkhead assembly, and tailgate assembly are riveted together by the bottom frame crossbeam and the roof crossbeam to form a complete rectangular vehicle frame.

[0012] As a further implementation, the A-type traction frame is connected to the bottom frame beam by riveting or high-strength bolts.

[0013] As a further implementation, the slender square tubes used in the left enclosure assembly, right enclosure assembly and front bulge assembly are aluminum alloy square tubes or high-strength steel square tubes.

[0014] As a further implementation, the A-type tow frame, front bulkhead assembly, left bulkhead assembly, right bulkhead assembly, bottom frame crossbeam, and roof crossbeam are connected to the skin using rivet fasteners.

[0015] As a further implementation, the drive gear is also fixedly connected to an operating handle, and the door panel of the downward-opening door is provided with a locking mechanism that engages the operating handle.

[0016] Secondly, the present invention also provides a method for using a modular, low-drag towable van, comprising the following steps:

[0017] When the bottom-opening door is opened, the operating handle drives the drive gear, which in turn drives the upper and lower pins. The upper pin disengages from the fixed upper hole and the split upper hole, and the lower pin disengages from the fixed lower hole and the split lower hole. During this process, the Z-shaped lever, under the action of the torsion spring, causes the locking pin to gradually move towards and insert into the locking hole. When the upper and lower pins are completely disengaged from the fixed upper hole and the split upper hole, the bottom-opening door can be opened. When the bottom-opening door is closed, the drive gear rotates in the opposite direction, and the upper pin inserts into the fixed upper hole and the split upper hole, while the lower pin inserts into the fixed lower hole and the split lower hole, thus locking the door. During this process, the lower pin pushes the drive part of the Z-shaped lever until it inserts into the fixed lower hole. At this point, the lower pin disengages from the drive part of the Z-shaped lever, keeping the locking pin disengaged from the locking hole.

[0018] When the swing door is opened, the drive gear moves the upper and lower pins. When the upper and lower pins disengage from the fixed upper and lower holes, the swing door is opened. When the swing door is closed, the drive gear rotates in the opposite direction, causing the upper and lower pins to insert into the fixed upper and lower holes, thus locking the door.

[0019] Compared with the prior art, the advantages and positive effects of this invention are:

[0020] This invention divides the van into an A-type towing frame, a front convex assembly, a left convex assembly, a right convex assembly, and a tailgate assembly. This modular structure allows for easy disassembly and replacement of any damaged component, resulting in a short maintenance cycle and low cost. The front convex assembly employs a U-shaped design, effectively guiding and dividing airflow. Compared to traditional flat-front vans, this significantly reduces air resistance at high speeds, thereby saving fuel consumption for the tractor unit. Simultaneously, the convex structure itself provides effective usable space, increasing cargo loading capacity. The bottom-opening door is equipped with a bolt lock assembly. The bolt lock assembly has an upper bolt and a lower bolt on either side of the drive gear. The upper bolt passes through the upper opening hole on the double-opening frame and inserts into the upper fixing hole on the outer frame. The lower bolt passes through the lower opening hole on the double-opening frame and inserts into the lower fixing hole on the outer frame. A double-opening locking assembly is installed inside the double-opening frame and interlocks with it. Through the linkage design of the double-opening locking assembly and the bolt lock assembly, when one of the swing or bottom-opening modes is activated, the other opening mode is mechanically locked. That is, when performing a bottom-opening operation, the bolt lock assembly locks the double-opening frame to the outer frame to prevent accidental swing opening; when performing a swing door operation, the double-opening locking assembly locks the double-opening frame to the bottom-opening door to prevent the bottom-opening mode from being activated, ensuring the safety and reliability of the operation process.

[0021] The front bumper assembly, left side assembly, right side assembly, and tailgate assembly of this invention are riveted together by the bottom frame crossbeam and roof crossbeam. The A-type tow frame is connected to the bottom frame crossbeam by riveting or high-strength bolts. Welded and riveted components are used for connection. The A-type tow frame, which bears concentrated stress, is designed as a welded component to ensure its structural strength and rigidity. The left and right side assemblies, which constitute the main body of the vehicle, are designed as riveted components. Utilizing the toughness of the riveted joints, the impact and vibration stress from road conditions are effectively absorbed and dispersed, improving the fatigue resistance and reliability of the entire vehicle structure. Simultaneously, the riveted connection has the advantages of vibration resistance and anti-loosening, making it particularly suitable for trailers that are frequently subjected to bumps. The riveting operation is fast and low-noise, significantly improving assembly efficiency. The left side assembly, right side assembly, front bumper assembly, bottom frame crossbeam, and roof crossbeam can all be disassembled into slender square tubes and frames for transport as individual parts, greatly saving transportation space and reducing logistics costs. Once at the destination, assembly can be completed by riveting using only simple tools and ordinary workers, without relying on complex welding processes and equipment. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a three-dimensional schematic diagram of the overall structure of the van of the present invention;

[0024] Figure 2 This is an exploded view of the main assembly components of the present invention;

[0025] Figure 3 This is a schematic diagram illustrating the present invention packaged and transported in disassembled form;

[0026] Figure 4 This is a schematic diagram of the tailgate assembly of the present invention;

[0027] Figure 5 This is a schematic diagram of the tailgate assembly of the present invention with a downward opening mechanism;

[0028] Figure 6 This is a schematic diagram of the structure of the locking and bolt locking assembly and the bolt locking assembly of the present invention.

[0029] In the diagram: 1. Type A towing frame; 2. Front bulkhead assembly; 21. Left front bulkhead; 22. Right front bulkhead; 3. Left bulkhead assembly; 31. Lower beam square tube; 32. Side beam vertical brace; 33. Upper beam square tube; 34. Column; 4. Right bulkhead assembly; 5. Tailgate assembly; 501. Outer frame; 502. Split frame; 503. Lower door; 504. Drive gear; 505. Upper pin; 506. Lower pin; 507. Split upper hole; 508. Fixed upper hole; 509. Split lower hole; 510. Fixed lower hole; 511. Z-shaped lever; 512. Torsion spring; 513. Locking pin; 514. Locking hole; 6. Bottom frame crossbeam; 7. Roof crossbeam; 8. Rivet; 9. Suspension tire assembly. Detailed Implementation

[0030] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Example 1

[0033] This embodiment provides a modular, low-drag towable van, such as... Figure 1 , Figure 2 , Figure 4 , Figure 5 and Figure 6As shown, the vehicle includes: an A-type towing frame 1, a front convex assembly 2, a left convex assembly 3, a right convex assembly 4, and a tailgate assembly 5. The front convex assembly 2 has a U-shaped structure with its pointed corners facing forward and is installed at the front end of the left convex assembly 3 and the right convex assembly 4. The tailgate assembly 5 is installed at the rear end of the left convex assembly 3 and the right convex assembly 4. The lower end of the left convex assembly 3 and the right convex assembly 4 is provided with a bottom frame crossbeam 6, and the upper end of the left convex assembly 3 and the right convex assembly 4 is provided with a roof crossbeam 7. The modular structure allows for easy disassembly and replacement of any damaged component, resulting in a short maintenance cycle and low cost. The unique U-shaped front convex design effectively guides and divides airflow, significantly reducing air resistance at high speeds compared to traditional flat-head cargo boxes, thereby saving fuel consumption of the tractor. At the same time, the front convex structure itself is an effective usable space, increasing the loading volume of goods.

[0034] The tailgate assembly 5 consists of an outer frame 501, a split frame 502, and a bottom door 503 arranged sequentially from the outside to the inside. The outer frame 501 and the split frame 502 are hinged at the side, and the split frame 502 and the bottom door 503 are hinged at the bottom. A bolt lock assembly is provided in the bottom door 503. An upper bolt 505 and a lower bolt 506 are respectively provided on both sides of the drive gear 504 of the bolt lock assembly. The upper bolt 505 passes through the split upper hole 507 on the split frame 502 and is inserted into the fixing upper hole 508 on the outer frame 501. The lower bolt 506 passes through the split lower hole 509 on the split frame 502 and is inserted into the fixing lower hole 510 on the outer frame 501. A split locking assembly is provided inside the split frame 502, and the split locking assembly is interlocked with the bolt lock assembly. Through the linkage design of the double-opening locking component and the bolt lock component, when one of the swing or bottom-opening modes is activated, the other opening mode is mechanically locked. That is, when the bottom-opening door 503 is operated, the bolt lock component will lock the double-opening frame 502 and the outer frame 501 to prevent the swing opening from happening unexpectedly; when the swing door is operated, the double-opening locking component will lock the double-opening frame 502 and the bottom-opening door 503 to prevent the bottom-opening mode from being opened, thus ensuring the safety and reliability of the operation process.

[0035] As a further implementation method, such as Figure 6As shown, the split locking assembly is disposed on one side of the split lower hole 509. The split locking assembly consists of a hinge shaft, a Z-shaped lever 511, a torsion spring 512, and a locking pin 513. The Z-shaped lever 511 is mounted in the split frame 502 via the hinge shaft. The torsion spring 512 is disposed between the Z-shaped lever 511 and the split frame 502. One end of the Z-shaped lever 511 is provided with a locking pin 513, and the other end is provided with a driving part. When the lower pin 506 is fully withdrawn from the split lower hole 509, the driving part abuts against the end of the lower pin 506, and the locking pin 513 is inserted into the locking hole 514 provided on the split frame 502 and the outer frame 501 under the action of the torsion spring 512; after the lower pin 506 is inserted into the split lower hole 509, the driving part abuts against the side of the lower pin 506, and the locking pin 513 is withdrawn from the locking hole 514 under the action of the lower pin 506.

[0036] As a further implementation, a rack is provided at one end of the upper pin 505 and the lower pin 506 near the drive gear 504. The rack meshes with the drive gear 504 to drive the upper pin 505 and the lower pin 506 to move, thereby unlocking and locking.

[0037] As a further implementation, the left side assembly 3 and the right side assembly 4 are respectively constructed from slender square tubes riveted together to form a planar frame; the A-type tow frame 1 is constructed from square tubes welded into a triangular load-bearing frame; the front bumper assembly 2, the left side assembly 3, the right side assembly 4, and the tailgate assembly 5 are riveted together by the bottom frame crossbeam 6 and the roof crossbeam 7 to form a complete rectangular cargo box frame; a suspension tire assembly 9 is installed below the bottom frame crossbeam 6. The A-type tow frame 1 is connected to the bottom frame crossbeam 6 by riveting or high-strength bolts. The system employs a combination of welded and riveted components for connection. The A-type tow frame 1, which bears concentrated stress, is designed as a welded component to ensure its structural strength and rigidity. The left and right side assemblies 3 and 4, which constitute the main body of the trailer, are designed as riveted components. Utilizing the toughness of the riveted joints, the system effectively absorbs and disperses the impact and vibration stress from road conditions, improving the fatigue resistance and reliability of the entire vehicle structure. Furthermore, the riveted connection offers advantages such as vibration resistance and prevention of loosening, making it particularly suitable for trailers frequently subjected to bumpy conditions. The riveting operation is fast and low-noise, significantly improving assembly efficiency.

[0038] As a further implementation, the slender square tubes used in the left side assembly 3, right side assembly 4, and front bumper assembly 2 are made of aluminum alloy or high-strength steel; the bottom frame crossbeam 6 and roof crossbeam 7 are also slender square tube structures. The left side assembly 3, right side assembly 4, front bumper assembly 2, bottom frame crossbeam 6, and roof crossbeam 7 can all be disassembled into slender square tubes and frames for transport as individual parts, greatly saving transportation space and reducing logistics costs. Upon arrival at the destination, assembly can be completed by riveting using only simple tools and ordinary workers, without relying on complex welding processes and equipment, making it particularly suitable for both individual parts export and assembly modes.

[0039] As a further implementation, the A-type traction frame 1, the front bulkhead assembly 2, the left bulkhead assembly 3, the right bulkhead assembly 4, the bottom frame crossbeam 6, and the roof crossbeam 7 are connected to the skin using rivet fasteners.

[0040] As a further implementation, the drive gear 504 is also fixedly connected to an operating handle, and the door panel of the downward-opening door 503 is provided with a locking mechanism that engages the operating handle.

[0041] The A-type tow frame 1 is made of high-strength rectangular steel pipe and welded to form a triangular frame structure similar to an aircraft skeleton to ensure its traction strength and rigidity. The two symmetrical parts of the front boom assembly 2 are welded together after being positioned on the tooling to ensure accuracy. They are riveted together by rivets 8 to form a complete U-shaped frame with the sharp corners facing forward, which is the front boom assembly 2.

[0042] like Figure 3 As shown, during transportation, the welded A-type tow frame 1, left front convex section 21, right front convex section 22, the slender square tubes forming the left and right convex sections 3 and 4, as well as the square tubes for other beams and the loose parts of the tailgate assembly 5, are compactly packed into one or more cubic cargo boxes, such as... Figure 3 As shown, this greatly saves container space.

[0043] During assembly at the destination:

[0044] Using the A-type towing frame 1 as a base, the left front bumper 21 and the right front bumper 22 are connected by high-strength rivets 8 to form a front bumper assembly 2 and fixed to the A-type towing frame 1. At the same time, the slender square tubes that make up the left side assembly 3 and the right side assembly 4, including the lower beam square tube 31, the side beam vertical support 32, the upper beam square tube 33, and the column 34, are assembled by rivets 8 to form the left and right side assemblies 4. Then, the left and right side assemblies 4 are respectively connected to the A-type towing frame 1 and the front bumper assembly 2. The bottom frame crossbeams 6 are evenly distributed and connected at the bottom of the left side assembly 3 and the right side assembly 4, and the roof crossbeams 7 are evenly distributed and connected at the top of the left side assembly 3 and the right side assembly 4. The tailgate assembly 5 is then assembled and connected, thus forming a preliminary vehicle frame. The user then connects the inner and outer skins and suspension components to assemble a complete towable van.

[0045] Example 2

[0046] This embodiment provides a method for using a modular, low-drag towable van, including the following steps:

[0047] When the bottom-opening door 503 is opened, the operating handle drives the drive gear 504, which in turn drives the upper pin 505 and the lower pin 506. The upper pin 505 disengages from the fixed upper hole 508 and the split upper hole 507, and the lower pin 506 disengages from the fixed lower hole 510 and the split lower hole 509. During this process, the Z-shaped lever 511, under the action of the torsion spring 512, causes the locking pin 513 to gradually move towards and be inserted into the locking hole 514. When the upper pin 505 and the lower pin 506 are completely disengaged from the fixed upper hole 508 and the split upper hole 507... Afterwards, the bottom-opening door 503 can be opened; when the bottom-opening door 503 is closed, the drive gear 504 rotates in the opposite direction, the upper pin 505 is inserted into the fixed upper hole 508 and the split upper hole 507, and the lower pin 506 is inserted into the fixed lower hole 510 and the split lower hole 509, thus achieving locking; during this process, the lower pin 506 pushes the drive part of the Z-shaped lever 511 until the lower pin 506 is inserted into the fixed lower hole 510, at which point the lower pin 506 disengages from the drive part of the Z-shaped lever 511, and keeps the locking pin in the state of disengaging from the locking hole 514;

[0048] When the swing door is opened, the drive gear 504 drives the upper pin 505 and the lower pin 506 to move. When the upper pin 505 and the lower pin 506 disengage from the fixed upper hole 508 and the fixed lower hole 510, the swing door is opened. When the swing door is closed, the drive gear 504 rotates in the opposite direction, causing the upper pin 505 and the lower pin 506 to insert into the fixed upper hole 508 and the fixed lower hole 510, thus locking the door.

[0049] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A modular, low-drag towable van, characterized in that, include: The vehicle comprises an A-type tow bracket, a front bumper assembly, a left side assembly, a right side assembly, and a tailgate assembly. The front bumper assembly has a U-shaped structure with its pointed corners facing forward and is installed at the front end of the left and right side assemblies. The tailgate assembly is installed at the rear end of the left and right side assemblies. The lower end of the left and right side assemblies is provided with a bottom frame crossbeam, and the upper end of the left and right side assemblies is provided with a roof crossbeam. The A-type tow bracket is located at the front end of the bottom frame crossbeam. The tailgate assembly comprises an outer frame, a double-leaf frame, and a lower door arranged sequentially from the outside in. The outer frame and the double-leaf frame are hinged at the sides, and the double-leaf frame and the lower door are hinged at the bottom. A bolt lock assembly is installed in the lower door. An upper bolt and a lower bolt are respectively provided on both sides of the drive gear of the bolt lock assembly. The upper bolt passes through the upper opening hole on the double-leaf frame and inserts into the upper fixing hole on the outer frame; the lower bolt passes through the lower opening hole on the double-leaf frame and inserts into the lower fixing hole on the outer frame. A double-leaf locking assembly is installed inside the double-leaf frame, and the double-leaf locking assembly interlocks with the bolt lock assembly. The double-leaf locking assembly is located within the double-leaf frame. On one side of the lower hole, the split locking assembly consists of a hinge shaft, a Z-shaped lever, a torsion spring, and a locking pin. The Z-shaped lever is mounted on the split frame via the hinge shaft. The torsion spring is provided between the Z-shaped lever and the split frame. One end of the Z-shaped lever is provided with a locking pin, and the other end is provided with a driving part. When the lower pin is fully withdrawn from the split lower hole, the driving part abuts against the end of the lower pin, and the locking pin is inserted into the locking hole provided on the split frame and the outer frame under the action of the torsion spring. After the lower pin is inserted into the split lower hole, the driving part abuts against the side of the lower pin, and the locking pin is withdrawn from the locking hole under the action of the lower pin. The left and right side assemblies are respectively formed by riveting slender square tubes to create a planar frame; the A-type traction frame is formed by welding square tubes into a triangular load-bearing frame; the bottom frame crossbeam and the roof crossbeam are slender square tube structures. The front bumper assembly, left side assembly, right side assembly, and tailgate assembly are riveted together by the bottom frame crossbeam and the roof crossbeam to form a complete rectangular vehicle frame.

2. The modular low-drag trailer as described in claim 1, characterized in that, The upper and lower pins are provided with racks at the ends near the drive gear, and the racks mesh with the drive gear.

3. The modular, low-drag trailer as described in claim 1, characterized in that, The A-type traction frame is connected to the bottom frame beam by riveting or high-strength bolts.

4. A modular, low-drag trailer as described in claim 3, characterized in that, The slender square tubes used in the left enclosure assembly, right enclosure assembly, and front bumper assembly are aluminum alloy square tubes or high-strength steel square tubes.

5. A modular, low-drag trailer as described in claim 1, characterized in that, The A-type tow frame, front bumper assembly, left bumper assembly, right bumper assembly, bottom frame crossbeam, and roof crossbeam are connected to the skin using rivet fasteners.

6. A modular, low-drag trailer as described in claim 1, characterized in that, The drive gear is also fixedly connected to an operating handle, and the door panel of the downward-opening door is provided with a locking mechanism that engages the operating handle.

7. The method of using a modular low-drag trailer as described in any one of claims 1-6, characterized in that, Includes the following steps: When the bottom-opening door is opened, the operating handle drives the drive gear, which in turn drives the upper and lower pins. The upper pin disengages from the fixed upper hole and the split upper hole, and the lower pin disengages from the fixed lower hole and the split lower hole. During this process, the Z-shaped lever, under the action of the torsion spring, causes the locking pin to gradually move towards and insert into the locking hole. When the upper and lower pins are completely disengaged from the fixed upper hole and the split upper hole, the bottom-opening door can be opened. When the bottom-opening door is closed, the drive gear rotates in the opposite direction, and the upper pin inserts into the fixed upper hole and the split upper hole, while the lower pin inserts into the fixed lower hole and the split lower hole, thus locking the door. During this process, the lower pin pushes the drive part of the Z-shaped lever until it inserts into the fixed lower hole. At this point, the lower pin disengages from the drive part of the Z-shaped lever, keeping the locking pin disengaged from the locking hole. When the swing door is opened, the drive gear moves the upper and lower pins. When the upper and lower pins disengage from the fixed upper and lower holes, the swing door is opened. When the swing door is closed, the drive gear rotates in the opposite direction, causing the upper and lower pins to insert into the fixed upper and lower holes, thus locking the door.

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