Tail brake device

Abstract

The utility model relates to a tail gate device. The tail gate device comprises a waist box, an opening and closing mechanism, a connecting mechanism and a gate, the waist box is used for being arranged at the section position of a flow channel, the connecting mechanism is arranged on the waist box, the gate is movably arranged in the waist box, the opening and closing mechanism is installed on the connecting mechanism, the opening and closing mechanism is connected with the gate, and the opening and closing mechanism is used for driving the gate to close or open the flow channel. The opening and closing mechanism comprises an oil cylinder, a connecting rod and a piston assembly, the oil cylinder is detachably connected with the connecting mechanism, one end of the connecting rod is movably arranged on the oil cylinder, the other end of the connecting rod is connected with the gate, and the piston assembly is arranged at the end, located on one side of the oil cylinder, of the connecting rod. The tail gate device has the advantages that maintenance is convenient and fast, the workload is reduced, and the maintenance efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of water gate equipment, and in particular to a tail gate device. Background Art

[0002] The sustainable operation of sluice equipment is the most basic requirement to ensure economic benefits, and the regular maintenance of sluice equipment is the guarantee for the continuous operation of sluice equipment. Pumped storage power stations especially require the sustainable operation of equipment. The simultaneous shutdown of multiple units is a serious production accident, which will have a serious impact on the economy and the power grid.

[0003] Generally, a tail gate device is set on the flow channel to close or open the flow channel, and the piston seal inside it needs to be replaced regularly. However, the conventional maintenance mode requires the entire opening and closing mechanism to be disassembled from the gate, which will damage the seal between the waist box and the sealing top cover during the maintenance, and the water in the flow channel needs to be emptied in advance, which will also affect the normal operation of other flow channels during the maintenance process. After the replacement is completed, the flow channel needs to be filled with water and pressure treatment, which prolongs the maintenance cycle. Therefore, the traditional tail gate device has the disadvantages of cumbersome maintenance, inconvenient operation, and low maintenance efficiency when replacing the seal ring. Summary of the invention

[0004] Based on this, it is necessary to provide a tail gate device to address the problems of cumbersome maintenance, inconvenient operation and low maintenance efficiency when replacing the sealing ring of the tail gate device.

[0005] A tail gate device comprises a waist box, an opening and closing mechanism, a connecting mechanism and a gate, wherein the waist box is used to be arranged at a cross-sectional position of a flow channel, the connecting mechanism is arranged on the waist box, the gate is movably arranged in the waist box, the opening and closing mechanism is installed on the connecting mechanism, the opening and closing mechanism is connected to the gate, and the opening and closing mechanism is used to drive the gate to close or open the flow channel;

[0006] The opening and closing mechanism includes a cylinder, a connecting rod and a piston assembly. The cylinder is detachably connected to the connecting mechanism. One end of the connecting rod is movably arranged on the cylinder, and the other end of the connecting rod is connected to the gate. The piston assembly is arranged at the end of the connecting rod located on one side of the cylinder.

[0007] In one embodiment, the waist box includes a sealed top cover, which is movably covered on the top of the waist box, and the opening and closing mechanism passes through the sealed top cover and is connected to the gate.

[0008] In one embodiment, the connecting mechanism includes a base and a lower cover, the base is mounted on the sealing top cover, the lower cover is detachably mounted on the base, the oil cylinder is detachably mounted on the lower cover, the oil cylinder is provided with an oil chamber, one end of the connecting rod is provided with a piston assembly and is movably arranged in the oil chamber, the other end of the connecting rod passes through the lower cover, the base and the sealing top cover and is connected to the gate, and there is a gap H between the piston assembly and the lower cover.

[0009] In one embodiment, the base and the lower cover are detachably connected via a first fastener, and the lower cover and the oil cylinder are detachably connected via a second fastener.

[0010] In one embodiment, the piston assembly includes a first piston and a second piston, the connecting rod is provided with a first step at one end where the piston assembly is installed, the first piston is sleeved on the first step, the connecting rod is further provided with a second step between the first step and the end face of the connecting rod, the second piston is sleeved on the second step, and the second piston abuts against the first piston.

[0011] In one embodiment, the piston assembly also includes a first sealing ring, a second sealing ring, a third sealing ring, a fourth sealing ring and a plurality of guide bands, wherein the first sealing ring is arranged between the first piston and the connecting rod, the second sealing ring is arranged on the outer side surface of the first piston, the third sealing ring is arranged between the second piston and the connecting rod, the fourth sealing ring is arranged on the outer side surface of the second piston, and a plurality of guide bands are arranged on the outer side surfaces of the first piston and the second piston.

[0012] In one embodiment, a first sealing member is provided at the connection between the sealing top cover and the waist box, and a second sealing member is provided at the connection between the waist box and the gate.

[0013] In one embodiment, the tail gate device further includes a gate locking mechanism, which is disposed on the sealing top cover and is used to lock the position of the gate.

[0014] In one of the embodiments, the oil cylinder is provided with an oil port, and the oil port is communicated with the oil chamber.

[0015] In one of the embodiments, the oil cylinder is further provided with a lifting lug, and the lifting lug is used to connect a device for suspending the oil cylinder.

[0016] The above-mentioned tail gate device drives the gate to move up and down in the waist box by setting an opening and closing mechanism, thereby closing or opening the flow channel, and a sealing top cover is set on the waist box to prevent the flow channel from flowing into the machine room. Specifically, the oil cylinder of the opening and closing mechanism is detachably installed on the connecting mechanism, and when the sealing ring of the piston assembly needs to be replaced, the gate is freely dropped to the bottom by gravity, and then the oil cylinder is disconnected from the connecting mechanism, and the oil cylinder is suspended from the connecting mechanism to separate the piston assembly from the oil cylinder, and then the sealing ring on the piston assembly is replaced to complete the maintenance process. The tail gate device described in the present application can replace the piston sealing ring of the tail gate device without removing the seal, emptying the flow channel, and affecting the normal operation of other flow channels, which has the advantages of convenient maintenance and improved maintenance efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a schematic diagram of the installation of the tailgate device described in an embodiment of the present application.

[0018] FIG. 2 is a schematic diagram of the structure of the tailgate device described in an embodiment of the present application.

[0019] FIG. 3 is an enlarged cross-sectional view of the tailgate device according to an embodiment of the present application.

[0020] FIG. 4 is a schematic diagram of the dismantling of the tailgate device described in an embodiment of the present application.

[0021] FIG. 5 is a schematic diagram of further dismantling of the tailgate device described in the embodiment of the present application.

[0022] FIG. 6 is a schematic structural diagram of a piston assembly of a tail brake device according to an embodiment of the present application.

[0023] Figure numbers: 110, waist box; 120, sealing top cover; 200, opening and closing mechanism; 210, oil cylinder; 210A, oil chamber; 211, oil port; 212, lifting ear; 220, piston assembly; 221, first piston; 222, second piston; 223, first sealing ring; 224, second sealing ring; 225, third sealing ring; 226, fourth sealing ring; 227, guide belt; 230, connecting rod; 231, first step; 232, second step; 300, connecting mechanism; 310, base; 311, first fastener; 320, lower cover; 321, second fastener; 330, support; 400, gate; 500, gate locking mechanism. DETAILED DESCRIPTION

[0024] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0025] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0026] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0027] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0028] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0029] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0030] Referring to Figures 1 and 2, Figure 1 shows an installation schematic diagram of a tail gate device in an embodiment of the present application, and Figure 2 shows a structural schematic diagram of a tail gate device in an embodiment of the present application. The tail gate device provided in an embodiment of the present application includes a waist box 110, a sealing top cover 120, an opening and closing mechanism 200, a connecting mechanism 300 and a gate 400. The waist box 110 is used to be set at a cross-sectional position of the flow channel, the sealing top cover 120 can be movably covered on the top of the waist box 110, the connecting mechanism 300 is arranged on the sealing top cover 120, the gate 400 can be movably arranged in the waist box 110, the opening and closing mechanism 200 is installed on the connecting mechanism 300, and the opening and closing mechanism 200 passes through the sealing top cover 120 to be connected with the gate 400, and the opening and closing mechanism 200 is used to drive the gate 400 to close or open the flow channel. Specifically, the opening and closing mechanism 200 includes a cylinder 210, a connecting rod 230 and a piston assembly 220. The cylinder 210 is detachably connected to the connecting mechanism 300. One end of the connecting rod 230 is movably arranged on the cylinder 210, and the other end of the connecting rod 230 is connected to the gate 400. The piston assembly 220 is arranged at the end of the connecting rod 230 on one side of the cylinder 210.

[0031] The tail gate device described in the embodiment of the present application drives the gate 400 to move up and down in the waist box 110 by setting the opening and closing mechanism 200, so that the gate 400 closes or opens the flow channel, and the sealing top cover 120 covers the top of the waist box 110 to prevent the flow channel from flowing into the machine room where the tail gate device is placed. Specifically, the oil cylinder 210 of the opening and closing mechanism 200 is detachably installed on the connecting mechanism 300 in the vertical direction. When the sealing ring of the piston assembly 220 needs to be replaced, the gate 400 is freely dropped to the bottom of the waist box 110 by gravity, and then the oil cylinder 210 is disconnected from the connecting mechanism 300, and the oil cylinder 210 is suspended from the connecting mechanism 300, so that the piston assembly 220 is separated from the oil cylinder 210, and then the sealing ring on the piston assembly 220 is replaced to complete the maintenance process.

[0032] The tail gate device described in the embodiment of the present application is detachably connected to the oil cylinder 210 by setting a connecting mechanism 300, so that during maintenance, only the oil cylinder 210 needs to be removed to complete the replacement of the sealing chamber of the piston assembly 220. The piston sealing ring of the tail gate device can be replaced without removing the seal, draining the water in the flow channel, and affecting the normal operation of other flow channels. It has the advantages of convenient maintenance and improved maintenance efficiency.

[0033] In combination with Figure 3, Figure 3 shows an enlarged sectional view of the tail gate device in an embodiment of the present application. In some embodiments, the connecting mechanism 300 includes a base 310 and a lower cover 320. The base 310 is installed on the sealing top cover 120, and the lower cover 320 is detachably installed on the base 310. The cylinder 210 is detachably installed on the lower cover 320. The cylinder 210 is provided with an oil chamber 210A. The connecting rod 230 is provided with one end of the piston assembly 220 movably arranged in the oil chamber 210A, and the other end of the connecting rod 230 passes through the lower cover 320, the base 310 and the sealing top cover 120 and is connected to the gate 400. There is a gap H between the piston assembly 220 and the lower cover 320. By setting the base 310 on the sealing top cover 120, the lower cover 320 is detachably mounted on the base 310, so that the connecting rod 230 is sealed through the lower cover 320 and passes into the waist box 110 to connect with the gate 400, thereby preventing the water in the flow channel from gushing out along with the connecting rod 230. The oil cylinder 210 is detachably mounted on the lower cover 320. When replacing the sealing ring, the lower cover 320 is disconnected from the oil cylinder 210, and the oil cylinder 210 can be disassembled to maintain and replace the piston assembly 220, which has the advantage of convenient operation. It should be noted that due to the gap H between the piston assembly 220 and the lower cover 320, when the lower cover 320 and the oil cylinder 210 are hoisted as a whole, in order to prevent the lower cover 320 from hitting the piston assembly 220, the maximum hoisting distance needs to be less than the gap H.

[0034] In an optional embodiment, as shown in FIG. 4 and FIG. 5 , the base 310 and the lower cover 320 are detachably connected via a first fastener 311, and the lower cover 320 and the oil cylinder 210 are detachably connected via a second fastener 321. In one example, the base 310 is provided with a first threaded countersunk hole, the lower cover 320 is provided with a first through hole at a position corresponding to the first threaded countersunk hole, the first fastener 311 is a screw or a bolt, and the first fastener 311 is installed downwardly into the first threaded countersunk hole through the first through hole; the oil cylinder 210 is provided with a second threaded countersunk hole, the lower cover 320 is provided with a second through hole at a position corresponding to the second threaded countersunk hole, the second fastener 321 is a screw or a bolt, and the second fastener 321 is installed upwardly into the second threaded countersunk hole through the second through hole. Since the second fastener 321 is installed between the base 310 and the lower cover 320, the lower cover 320 and the oil cylinder 210 need to be lifted as a whole before the second fastener 321 can be removed. When lifting the lower cover 320 and the oil cylinder 210, the maximum lifting distance needs to be less than the gap H. After lifting, a support member 330 can be placed between the base 310 and the lower cover 320 to facilitate the disassembly of the second fastener 321. After removing the second fastener 321, the oil cylinder 210 can be lifted alone, thereby replacing the sealing ring of the piston assembly 220.

[0035] In an optional embodiment, as shown in FIG6 , the piston assembly 220 includes a first piston 221 and a second piston 222, and the connecting rod 230 is provided with a first step 231 at one end where the piston assembly 220 is installed, and the first piston 221 is sleeved on the first step 231. The connecting rod 230 is also provided with a second step 232 between the first step 231 and the end face of the connecting rod 230, and the second piston 222 is sleeved on the second step 232, and the second piston 222 abuts against the first piston 221, that is, the second piston 222 is arranged at the end position. By arranging the first step 231 and the second step 232 on the connecting rod 230, the first piston 221 and the second piston 222 are respectively clamped on the first step 231 and the second step 232, so that the first piston 221 and the second piston 222 can be conveniently installed and positioned. Specifically, the second piston 222 at the end is a load-bearing piston, which is used to withstand the oil pressure in the oil cylinder 210.

[0036] In an optional embodiment, as shown in FIG6 , the piston assembly 220 further includes a first sealing ring 223, a second sealing ring 224, a third sealing ring 225, a fourth sealing ring 226, and a plurality of guide bands 227. The first sealing ring 223 is disposed between the first piston 221 and the connecting rod 230, the second sealing ring 224 is disposed on the outer side of the first piston 221, the third sealing ring 225 is disposed between the second piston 222 and the connecting rod 230, the fourth sealing ring 226 is disposed on the outer side of the second piston 222, and a plurality of guide bands 227 are disposed on the outer side of the first piston 221 and the second piston 222. In one example, the first sealing ring 223 and the third sealing ring 225 are O-rings, the second sealing ring 224 is a V-shaped combined sealing ring, and the fourth sealing ring 226 is a coaxial combined sealing ring. By providing the first sealing ring 223, the second sealing ring 224, the third sealing ring 225, the fourth sealing ring 226 and a plurality of guide belts 227, the first piston 221 and the second piston 222 are in close contact with the inner wall of the cylinder 210, thereby avoiding leakage of the oil in the cylinder 210, and having the advantages of stable movement, leakage prevention and reduced wear.

[0037] In an optional embodiment, a first seal is provided at the connection between the sealing top cover 120 and the waist box 110, and a second seal is provided at the connection between the waist box 110 and the gate 400. By providing the first seal, the sealing top cover 120 can be sealed to prevent water in the flow channel from flowing in through the gap of the sealing top cover 120 to cause damage to the equipment, thereby ensuring stable operation of the equipment. A second seal is provided between the waist box 110 and the gate 400, so that when the gate 400 is closed, water in the flow channel cannot flow through the gap between the gate 400 and the waist box 110, thereby ensuring the stability of the equipment operation.

[0038] In an optional embodiment, as shown in FIG1 , the tailgate device further includes a gate locking mechanism 500, which is disposed on the sealing top cover 120 and is used to lock the position of the gate 400. In order to fix the gate 400 at the same position after the opening and closing mechanism 200 has adjusted its position, the gate locking mechanism 500 is provided to complete the locking.

[0039] In an optional embodiment, as shown in FIG3 , the oil cylinder 210 is provided with an oil port 211, and the oil port 211 is connected to the oil chamber 210A. By providing the oil port 211 to be connected to the oil chamber 210A, when the sealing ring needs to be replaced, the oil in the oil cylinder 210 is pumped out, and the oil port 211 is connected to the atmosphere, so that air is introduced into the oil chamber 210A, so that the piston assembly 220 and the connecting rod 210 automatically slide to the lowest part under the traction of the gate 400's own weight, so that the oil cylinder 210 can be easily disassembled.

[0040] In an optional embodiment, as shown in FIG2 , the oil cylinder 210 is further provided with a lifting lug 212, and the lifting lug 212 is used to connect a device for suspending the oil cylinder 210. During the process of replacing the sealing ring, the oil cylinder 210 needs to be lifted by an external device, and by providing the lifting lug 212, a rope can be fixed to the lifting lug 212, thereby conveniently lifting the oil cylinder 210.

[0041] On the other hand, the present application also provides a method for replacing a piston sealing ring of a tail gate device, using the tail gate device described in any of the above embodiments, comprising the following steps:

[0042] S100: closing the gate 400 to a fully closed state;

[0043] S200: lifting the lower cover 320 of the connection mechanism 300 and the oil cylinder 210 together to separate from the base 310 of the connection mechanism 300, with the lifting height being less than the gap H;

[0044] S300: placing a support member 330 between the lower cover 320 and the base 310;

[0045] S400: lifting the oil cylinder 210 and separating it from the lower cover 320, so that the piston assembly 220 is separated from the oil cylinder 210;

[0046] S500: Replace the sealing ring on the piston assembly 220;

[0047] S600: After the replacement is completed, the oil cylinder 210 is installed on the lower cover 320 , and after the support member 330 is taken out, the lower cover 320 is installed on the base 310 .

[0048] The method for replacing the piston seal ring of the tail gate device described in the present application is to let the gate 400 fall freely to the bottom of the waist box 110 by gravity, then disconnect the oil cylinder 210 from the connecting mechanism 300, detach the oil cylinder 210 from the connecting mechanism 300, and then replace the seal ring on the piston assembly 220 to complete the maintenance process. By setting the connecting mechanism 300 to detachably connect the oil cylinder 210, only the oil cylinder 210 needs to be removed during maintenance to complete the replacement of the sealing chamber of the piston assembly 220. The piston seal ring of the tail gate device can be replaced without removing the seal, emptying the water in the flow channel, and affecting the normal operation of other flow channels, which has the advantages of convenient maintenance, reduced workload, and improved maintenance efficiency.

[0049] The tailgate device described in the embodiment of the present application has the following beneficial effects:

[0050] 1. The connecting mechanism 300 is provided to detachably connect the oil cylinder 210, so that during maintenance, only the oil cylinder 210 needs to be removed to complete the replacement of the sealing chamber of the piston assembly 220. The piston sealing ring of the tail gate device can be replaced without removing the seal, draining the water in the flow channel, and affecting the normal operation of other flow channels, which has the advantages of convenient maintenance, reduced workload, and improved maintenance efficiency.

[0051] 2. By setting the base 310 on the sealing top cover 120, the lower cover 320 is detachably installed on the base 310, so that the connecting rod 230 is sealed through the lower cover 320 to pass into the waist box 110 and connect with the gate 400, avoiding the water in the flow channel from gushing out along with the connecting rod 230, thereby ensuring the stable operation of the equipment.

[0052] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0053] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A tailgate device, characterized in that: The invention comprises a waist box (110), an opening and closing mechanism (200), a connecting mechanism (300) and a gate (400), wherein the waist box (110) is used to be arranged at a cross-sectional position of a flow channel, the connecting mechanism (300) is arranged on the waist box (110), the gate (400) is movably arranged in the waist box (110), the opening and closing mechanism (200) is installed on the connecting mechanism (300), the opening and closing mechanism (200) is connected to the gate (400), and the opening and closing mechanism (200) is used to drive the gate (400) to close or open the flow channel; The opening and closing mechanism (200) comprises an oil cylinder (210), a connecting rod (230) and a piston assembly (220); the oil cylinder (210) is detachably connected to the connecting mechanism (300); one end of the connecting rod (230) is movably arranged on the oil cylinder (210); the other end of the connecting rod (230) is connected to the gate (400); and the piston assembly (220) is arranged at an end of the connecting rod (230) located on one side of the oil cylinder (210).

2. The tailgate device according to claim 1, characterized in that: The waist box (110) comprises a sealing top cover (120), the sealing top cover (120) is movably covered on the top of the waist box (110), and the opening and closing mechanism (200) passes through the sealing top cover (120) and is connected to the gate (400).

3. The tailgate device according to claim 2, characterized in that: The connecting mechanism (300) comprises a base (310) and a lower cover (320); the base (310) is mounted on the sealing top cover (120); the lower cover (320) is detachably mounted on the base (310); the oil cylinder (210) is detachably mounted on the lower cover (320); the oil cylinder (210) is provided with an oil chamber (210A); the connecting rod (230) is provided with a piston assembly (220) and one end is movably arranged in the oil chamber (210A); the other end of the connecting rod (230) passes through the lower cover (320), the base (310) and the sealing top cover (120) to be connected to the gate (400); and a gap H is provided between the piston assembly (220) and the lower cover (320).

4. The tailgate device according to claim 3, characterized in that: The base (310) and the lower cover (320) are detachably connected via a first fastener (311), and the lower cover (320) and the oil cylinder (210) are detachably connected via a second fastener (321).

5. The tailgate device according to any one of claims 1 to 4, characterized in that: The piston assembly (220) comprises a first piston (221) and a second piston (222); the connecting rod (230) is provided with a first step (231) at one end on which the piston assembly (220) is mounted; the first piston (221) is sleeved on the first step (231); the connecting rod (230) is further provided with a second step (232) between the first step (231) and an end surface of the connecting rod (230); the second piston (222) is sleeved on the second step (232), and the second piston (222) abuts against the first piston (221).

6. The tailgate device according to claim 5, characterized in that: The piston assembly (220) further comprises a first sealing ring (223), a second sealing ring (224), a third sealing ring (225), a fourth sealing ring (226) and a plurality of guide bands (227); the first sealing ring (223) is arranged between the first piston (221) and the connecting rod (230); the second sealing ring (224) is arranged on the outer side surface of the first piston (221); the third sealing ring (225) is arranged between the second piston (222) and the connecting rod (230); the fourth sealing ring (226) is arranged on the outer side surface of the second piston (222); and the plurality of guide bands (227) are arranged on the outer side surfaces of the first piston (221) and the second piston (222).

7. The tailgate device according to claim 2, characterized in that: A first sealing member is provided at the connection between the sealing top cover (120) and the waist box (110), and a second sealing member is provided at the connection between the waist box (110) and the gate (400).

8. The tailgate device according to claim 2, characterized in that: The tailgate device further comprises a gate locking mechanism (500), wherein the gate locking mechanism (500) is arranged on the sealing top cover (120), and the gate locking mechanism (500) is used to lock the position of the gate (400).

9. The tailgate device according to claim 3, characterized in that: The oil cylinder (210) is provided with an oil port (211), and the oil port (211) is communicated with the oil chamber (210A).

10. The tailgate device according to claim 1, characterized in that: The oil cylinder (210) is also provided with a lifting lug (212), and the lifting lug (212) is used to connect a device for suspending the oil cylinder (210).

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