A coal bin sub-bunker flow-aiding device

Abstract

The present application relates to raw coal feeding technology field, especially a kind of raw coal bunker sub-bunker flow aid, including, cleaning component, including bunker, with the installation pipeline being connected with the bunker, and the cleaning assembly being set in the installation pipeline;Adjusting component, including the bifurcated pipeline being communicated with the installation pipeline, the lifting assembly being set in the bifurcated pipeline, and the opening and closing assembly being connected with the lifting assembly;And, installation component, including the positioning slot being opened on the bifurcated pipeline, with the positioning slot being connected with the top plate, and with the dismounting assembly being connected with the top plate, air source is punched into bunker by installation pipeline with high-pressure air, high-pressure air will piston head top open, while high-pressure air is sprayed along the fitting slope of piston head and installation pipeline, can be swept and collected 360 ° omnidirectionally, adjusting component can be unfolded or folded, change the area of high-pressure air flow in installation pipeline, and then high-pressure air flow rate can be changed.

Description

Technical Field

[0001] This invention relates to the field of raw coal feeding technology, and in particular to a raw coal bunker silo distribution and flow aid device. Background Technology

[0002] Blockages, bulging, and arching are common problems in silos and chutes. The main solutions are vibrating motors and air cannons. The motor works by using high-frequency vibration to clear blockages, while the air cannon works by releasing high-pressure gas to break up blockages.

[0003] The main problem with vibratory motors is that they operate passively. Specifically, the motor only starts working when there is a blockage signal. Often, by this time, the material has already been accumulating in the silo for a long time, and the vibration simply cannot clear the material. Sometimes, the more it vibrates, the more solid the material becomes. Air cannons, on the other hand, are basically operated manually on-site. They are activated when a blockage is detected. Air cannons can be effective in large silos. However, the disadvantage is that the high-pressure gas blown by the air cannon is sprayed forward, resulting in a smaller impact range and lower efficiency. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] Given that the existing methods described above cannot effectively solve the problem of material blockage, this invention is proposed.

[0006] Therefore, the purpose of this invention is to provide a raw coal bunker distribution and flow aid device.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a raw coal bunker silo flow aid device, comprising a cleaning component, including a silo, an installation pipe connected to the silo, and a cleaning assembly disposed within the installation pipe;

[0008] The adjusting component includes a branch pipe communicating with the installation pipe, a lifting assembly disposed within the branch pipe, and an opening / closing assembly connected to the lifting assembly; and,

[0009] The installation components include a positioning groove formed on the branch pipe, a top plate connected to the positioning groove, and a disassembly assembly connected to the top plate.

[0010] As a preferred embodiment of the raw coal bunker distribution and flow aid device of the present invention, the cleaning component includes a fixed plate disposed on the inner wall of the installation pipe, a sliding rod connected to the fixed plate, a piston head connected to one end of the sliding rod, an adjusting bolt connected to the other end of the sliding rod, and a return spring disposed on the periphery of the sliding rod.

[0011] As a preferred embodiment of the raw coal bunker flow aid device of the present invention, the fixed plate is provided with a plurality of flow holes, the piston head is provided with a contacting inclined surface on the side that is in contact with the installation pipe, the other end of the sliding rod is provided with a thread, and the sliding rod is connected to the adjusting bolt through the thread.

[0012] As a preferred embodiment of the raw coal bunker flow aid device of the present invention, the lifting assembly includes a sealing plate that fits against the inner wall of the branch pipe, a mounting frame connected to the sealing plate, an elastic gasket disposed at the bottom of the mounting frame, a first hinge seat connected to the mounting frame, a transmission rod connected to the first hinge seat, a second hinge seat connected to the transmission rod, and a lifting plate connected to the second hinge seat.

[0013] As a preferred embodiment of the raw coal bunker distribution and flow aid device of the present invention, the mounting frame and the lifting plate are both provided with arched openings, and two sets of the first hinge seat, the second hinge seat, and the transmission rod are provided, which cooperate with the mounting frame and the lifting plate to form a simple parallelogram.

[0014] As a preferred embodiment of the raw coal bunker distribution and flow aid device of the present invention, the opening and closing assembly includes a first rotating rod rotatably connected to the mounting frame, a third hinge seat connected to the first rotating rod, a connecting rod connected to the third hinge seat, an auxiliary rod connected to the connecting rod, a fourth hinge seat connected to the auxiliary rod, a second rotating rod connected to the fourth hinge seat, and an opening and closing piece connected to the second rotating rod.

[0015] In a preferred embodiment of the raw coal bunker distribution and flow aid device of the present invention, the opening and closing plate is connected to the lifting plate, and two sets of opening and closing components are provided, which are symmetrically arranged about the lifting plate.

[0016] As a preferred embodiment of the raw coal bunker distribution and flow aid device of the present invention, the disassembly and assembly assembly includes a passage hole opened on the top plate, a receiving cavity opened in the top plate, a limiting spring disposed in the receiving cavity, a limiting plate connected to the limiting spring, a through hole opened on the limiting plate, a pull plate connected to the sealing plate, and an unlocking plate used in conjunction with the pull plate.

[0017] As a preferred embodiment of the raw coal bunker flow aid device of the present invention, two passage holes and two through holes are provided, the passage holes are connected to the receiving cavity, and the pull plate and the unlocking plate are located in different passage holes and through holes respectively.

[0018] As a preferred embodiment of the raw coal bunker distribution and flow aid device of the present invention, wherein: the limiting plate is provided with a displacement inclined surface, the pull plate and the unlocking plate are respectively provided with a squeezing inclined surface, and the bottom end of the unlocking plate is provided with a limiting protrusion.

[0019] The beneficial effects of the present invention are as follows: In the present invention, the air source injects high-pressure air into the hopper through the installation pipe. The high-pressure air pushes open the piston head, and at the same time, the high-pressure air is sprayed out along the inclined surface of the piston head and the installation pipe, which can clean the collected material in all directions in 360°. The adjustment component can be unfolded or folded to change the area of ​​high-pressure air circulation in the installation pipe, thereby changing the high-pressure air flow rate and achieving the need to change the impact force as required. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of a coal bunker distribution and flow aid device.

[0022] Figure 2 This is a schematic diagram of a cross-section of a raw coal bunker distribution and flow aid device.

[0023] Figure 3 This is a schematic diagram of a cleaning component of a raw coal bunker distribution and flow aid device.

[0024] Figure 4 This is a schematic diagram showing the unfolding of the lifting and opening / closing components of a raw coal bunker distribution and flow aid device.

[0025] Figure 5 This is a schematic diagram showing the folding of the lifting and opening / closing components of a raw coal bunker distribution and flow aid device.

[0026] Figure 6 This is a schematic diagram of the assembly and disassembly components of a raw coal bunker distribution and flow aid device.

[0027] Figure 7 This is a cross-sectional schematic diagram of the assembly and disassembly components of a raw coal bunker distribution and flow aid device. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0032] Example 1

[0033] Reference Figures 1-3 This is the first embodiment of the present invention. This embodiment provides a raw coal bunker silo flow aid device, including a cleaning component 100, including a silo 101, wherein the silo 101 is a discharge silo 101 or other part that is prone to blockage, an installation pipe 102 connected to the silo 101, wherein the installation pipe 102 and the silo 101 can be connected by means of flange or screw locking, etc., and the end of the installation pipe 102 away from the silo 101 is provided with an internal thread to facilitate connection with an air source or air supply pipe, and a cleaning component 103 disposed in the installation pipe 102, wherein the cleaning component 103 completes the material clearing by the impact of high pressure gas;

[0034] Adjustment component 200 includes a branch pipe 201 connected to installation pipe 102, wherein lifting component 202 and opening / closing component 203 are installed and disassembled in installation pipe 102 through branch pipe 201. Lifting component 202 is installed in branch pipe 201, wherein operating lifting component 202 changes the position of opening / closing component 203, thereby installing opening / closing component 203 in installation pipe 102. Opening / closing component 203 connected to lifting component 202 can be unfolded or folded. By adjusting the folding angle of opening / closing component 203, the area of ​​high-pressure air flow in installation pipe 102 is controlled, thereby changing the flow rate of high-pressure air.

[0035] The mounting component 300 includes a positioning groove 301 formed on the branch pipe 201, through which the top plate 302 can be quickly installed on the branch pipe 201. The top plate 302 connected to the positioning groove 301 can provide protection for the adjusting component 200 to avoid accidental damage. The disassembly and assembly component 303 connected to the top plate 302 is used for quick operation of the adjusting component 200.

[0036] Specifically, the cleaning component 103 includes a fixing plate 103a fixed to the inner wall of the installation pipe 102. The fixing plate 103a guides the movement of the sliding rod 103b. When high-pressure air flows in the installation pipe 102, the sliding rod 103b connected to the fixing plate 103a will be pushed to move. A piston head 103c is connected to one end of the sliding rod 103b. The movement of the sliding rod 103b will cause the piston head 103c to move and separate from the installation pipe 102. An adjusting bolt 103d is connected to the other end of the sliding rod 103b. Rotating the adjusting bolt 103d can adjust the elastic coefficient of the return spring 103e, thereby changing the return speed of the sliding rod 103b and the piston head 103c. The return spring 103e is set on the periphery of the sliding rod 103b.

[0037] Furthermore, the fixed plate 103a has several flow holes 103f, which are used to ensure the normal flow of high-pressure air. The piston head 103c has a contact slope on the side that is in contact with the installation pipe 102, which can improve the sealing degree and increase the contact area between the piston head 103c and the installation pipe 102, so that the installation pipe 102 can better withstand the force of the piston head 103c when it rebounds. The piston head 103c is made of mold steel. After the piston head 103c is reset, it can effectively protect the parts inside the installation pipe 102 and prevent materials from entering the installation pipe 102. The other end of the sliding rod 103b is provided with threads. The sliding rod 103b is connected to the adjusting bolt 103d through the threads. One end of the return spring 103e abuts against the fixed plate 103a, and the other end abuts against the adjusting bolt 103d. The length of the return spring 103e can be adjusted by rotating the adjusting bolt 103d.

[0038] Operation process: Multiple units of this device are installed on the silo 101 to ensure all-round unblocking of the silo 101. The installation pipe 102 is connected to the air source. During installation, the elasticity of the return spring 103e can be adjusted in advance by operating the adjusting bolt 103d. During use, high-pressure air enters the installation pipe 102 and contacts the piston head 103c through the flow hole 103f on the fixed plate 103a. The high-pressure air pushes the piston head 103c and the sliding rod 103b. At this time, the return spring 103e is compressed, the piston head 103c separates from the installation pipe 102, and the high-pressure air is sprayed onto the material in the silo 101 through the gap between the piston head 103c and the installation pipe 102. Areas prone to material accumulation are swept 360° without dead angles to complete the unblocking work. The air source is intermittently supplied with air. When the air is exhausted, the return spring 103e returns to its original state, driving the sliding rod 103b and piston head 103c to reset. After the piston head 103c resets, it can effectively protect the parts inside the installation pipe 102 and prevent materials from entering the installation pipe 102. Even if a small amount of material enters, it will be blown out in the next air blowing. The operation of the cleaning component 100 can be automatically controlled. The matching control system can adjust the gas pulse, interval and circulation time according to the site conditions. The air sweeping device starts working when the material is moving to prevent the material from gradually accumulating.

[0039] Example 2

[0040] Reference Figures 4-5 This is the second embodiment of the present invention. Unlike the first embodiment, the lifting assembly 202 includes a sealing plate 202a that fits against the inner wall of the branch pipe 201. The sealing plate 202a can slide along the branch pipe 201 and also has a sealing function to prevent high-pressure air from being ejected from the branch pipe 201. A mounting bracket 202b is connected to the sealing plate 202a, providing space for the installation of other parts. An elastic gasket 202c is disposed at the bottom of the mounting bracket 202b. When the sealing plate 202a, along with the mounting bracket 202b, moves down to the bottom, the elastic gasket 202c contacts the mounting pipe 102. A first hinge seat 202d is connected to the mounting bracket 202b. A transmission rod 202e is connected to the first hinge seat 202d. A second hinge seat 202f is connected to the transmission rod 202e. A lifting plate 202g is connected to the second hinge seat 202f.

[0041] Specifically, both the mounting frame 202b and the lifting plate 202g have arched openings, through which the sliding rod 103b passes. Two sets of first hinge seats 202d, second hinge seats 202f, and transmission rods 202e are provided, which, together with the mounting frame 202b and the lifting plate 202g, form a simple parallelogram. As the sealing plate 202a moves down with the mounting frame 202b, the lifting plate 202g first contacts the installation pipe 102. As the mounting frame 202b continues to move down, the lifting plate 202g moves along the length of the installation pipe 102 through the cooperation between the first hinge seat 202d, the second hinge seat 202f, and the transmission rod 202e.

[0042] Furthermore, the opening and closing assembly 203 includes a first rotating rod 203a rotatably connected to the mounting frame 202b, a third hinge seat 203b connected to the first rotating rod 203a, a connecting rod 203c connected to the third hinge seat 203b, an auxiliary rod 203d rotatably connected to the connecting rod 203c, a fourth hinge seat 203e connected to the auxiliary rod 203d, a second rotating rod 203f connected to the fourth hinge seat 203e, and an opening and closing plate 203g connected to the second rotating rod 203f. When the positions of the mounting frame 202b and the lifting plate 202g change, the mounting frame 202b will pull the opening and closing plate 203g through the connecting rod 203c and the auxiliary rod 203d, thereby controlling the opening and closing of the plate.

[0043] Furthermore, the opening and closing plate 203g is rotatably connected to the lifting plate 202g. Two sets of opening and closing components 203 are provided and are symmetrically arranged about the lifting plate 202g. The opening and closing plate 203g is aligned on the lifting plate 202g to adjust the area of ​​high-pressure air circulation in the installation pipe 102.

[0044] The rest of the structure is the same as in Example 1.

[0045] Operation process: Since the mounting plate, lifting plate 202g, and transmission rod 202e are simple parallelograms, in their natural state, the lifting plate 202g is located at the lower position. The downward movement of the sealing plate 202a will simultaneously drive the mounting frame 202b downward. The lifting plate 202g first contacts the installation pipe 102. As the mounting frame 202b continues to move downward along the branch pipe 201, the engagement between the first hinge seat 202d, the second hinge seat 202f, and the transmission rod 202e will cause the lifting plate 202g to move along the length of the installation pipe 102 until the elastic gasket 202c contacts the installation pipe 102. When the mounting frame 202b moves downward along the branch pipe 201 and the lifting plate 202g moves horizontally along the installation pipe 102, the... As the connecting rod 203c and auxiliary rod 203d gradually change from an inclined state to a horizontal state, the first rotating rod 203a and the second rotating rod 203f rotate the auxiliary connecting rod 203c and auxiliary rod 203d to a horizontal state. Since the total length of the connecting rod 203c and auxiliary rod 203d remains unchanged, their projection length on the horizontal plane gradually increases, causing the opening and closing piece 203g to rotate around the lifting plate 202g, thereby changing from a folded state to an unfolded state. This reduces the area of ​​high-pressure air circulation in the installation pipe 102 and accelerates the high-pressure air flow rate. Similarly, moving the mounting bracket 202b upward along the branch pipe 201 will cause the opening and closing piece 203g to change from an unfolded state to a folded state, expanding the area of ​​high-pressure air circulation in the installation pipe 102.

[0046] Example 3

[0047] Reference Figures 6-7 This is the third embodiment of the present invention. Unlike the previous embodiments, the disassembly / assembly assembly 303 includes a passage hole 303a on the top plate 302, a pull-out plate 303f and an unlocking plate 303g passing through the passage hole 303a and the through hole 303e, a receiving cavity 303b within the top plate 302, a limiting spring 303c within the receiving cavity 303b, a limiting plate 303d connected to the limiting spring 303c (used to limit the pull-out plate 303f), a through hole 303e on the limiting plate 303d, a pull-out plate 303f fixedly connected to the sealing plate 202a (operating the pull-out plate 303f can move the sealing plate 202a up and down), and an unlocking plate 303g used in conjunction with the pull-out plate 303f (the unlocking plate 303g is only slidably connected to the through hole 303e on the limiting plate 303d).

[0048] Specifically, there are two passage holes 303a and two through holes 303e. The passage hole 303a is connected to the receiving cavity 303b. The pull plate 303f and the unlocking plate 303g are located in different passage holes 303a and through holes 303e, respectively.

[0049] Furthermore, the limiting plate 303d has a displacement ramp, the pull plate 303f has two extrusion ramps to form a limiting groove that matches the left end of the limiting plate 303d, the unlocking plate 303g has an extrusion ramp on its side, and the bottom end of the unlocking plate 303g has a limiting protrusion. The limiting protrusion can prevent the unlocking plate 303g from disengaging from the limiting plate 303d when it moves upward.

[0050] The rest of the structure is the same as in Example 2.

[0051] Operation process: When in use, first move the unlocking plate 303g upward. The pressing slope on the unlocking plate 303g cooperates with the displacement slope to make the limiting plate 303d move towards the limiting spring 303c. At this time, the limiting spring 303c is compressed, and the limiting plate 303d separates from the pull plate 303f. By operating the pull plate 303f, the sealing plate 202a can be moved up and down, thereby controlling the deformation of the adjusting component 200. Move the unlocking plate 303g downward. At this time, the limiting spring 303c resets, so that the limiting plate 303d abuts against the pull plate 303f, thereby limiting the limiting plate 303d and preventing the adjusting component 200 from being accidentally deformed.

[0052] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure performing the function described herein, and not only structural equivalents but also equivalent structures. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0053] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the invention as currently considered, or those features that are not relevant to implementing the invention) may be omitted.

[0054] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0055] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A raw coal bunker distribution and flow aid device, characterized in that: include, The cleaning component (100) includes a hopper (101), an installation pipe (102) connected to the hopper (101), and a cleaning assembly (103) disposed in the installation pipe (102). The cleaning assembly (103) includes a fixed plate (103a) disposed on the inner wall of the installation pipe (102), a sliding rod (103b) connected to the fixed plate (103a), a piston head (103c) connected to one end of the sliding rod (103b), an adjusting bolt (103d) connected to the other end of the sliding rod (103b), and a return spring (103e) disposed around the sliding rod (103b). The fixed plate (103a) is provided with several flow holes (103f), the piston head (103c) is provided with a contacting slope on the side that is in contact with the installation pipe (102), the other end of the sliding rod (103b) is provided with a thread, and the sliding rod (103b) is connected to the adjusting bolt (103d) through the thread. The adjusting component (200) includes a branch pipe (201) communicating with the installation pipe (102), a lifting assembly (202) disposed in the branch pipe (201), and an opening and closing assembly (203) connected to the lifting assembly (202). The lifting assembly (202) includes a sealing plate (202a) that fits against the inner wall of the branch pipe (201), a mounting bracket (202b) connected to the sealing plate (202a), an elastic gasket (202c) disposed at the bottom of the mounting bracket (202b), a first hinge seat (202d) connected to the mounting bracket (202b), a transmission rod (202e) connected to the first hinge seat (202d), a second hinge seat (202f) connected to the transmission rod (202e), and a lifting plate (202g) connected to the second hinge seat (202f). Both the mounting frame (202b) and the lifting plate (202g) are provided with arched openings. The first hinge seat (202d), the second hinge seat (202f), and the transmission rod (202e) are provided in two sets, and together with the mounting frame (202b) and the lifting plate (202g), they form a simple parallelogram. The opening and closing assembly (203) includes a first rotating rod (203a) rotatably connected to the mounting bracket (202b), a third hinge seat (203b) connected to the first rotating rod (203a), a connecting rod (203c) connected to the third hinge seat (203b), an auxiliary rod (203d) connected to the connecting rod (203c), a fourth hinge seat (203e) connected to the auxiliary rod (203d), a second rotating rod (203f) connected to the fourth hinge seat (203e), and an opening and closing piece (203g) connected to the second rotating rod (203f). The opening / closing plate (203g) is connected to the lifting plate (202g), and two sets of the opening / closing assembly (203) are provided, symmetrically arranged about the lifting plate (202g); and, The mounting component (300) includes a positioning groove (301) formed on the branch pipe (201), a top plate (302) connected to the positioning groove (301), and a disassembly assembly (303) connected to the top plate (302).

2. The raw coal bunker distribution and flow aid device as described in claim 1, characterized in that: The disassembly and assembly assembly (303) includes a passage hole (303a) on the top plate (302), a receiving cavity (303b) in the top plate (302), a limiting spring (303c) in the receiving cavity (303b), a limiting plate (303d) connected to the limiting spring (303c), a through hole (303e) on the limiting plate (303d), a pull plate (303f) connected to the sealing plate (202a), and an unlocking plate (303g) used in conjunction with the pull plate (303f).

3. The raw coal bunker distribution and flow aid device as described in claim 2, characterized in that: There are two passage holes (303a) and two through holes (303e). The passage hole (303a) is connected to the receiving cavity (303b). The pull plate (303f) and the unlocking plate (303g) are located in different passage holes (303a) and through holes (303e), respectively.

4. The raw coal bunker distribution and flow aid device as described in claim 3, characterized in that: The limiting plate (303d) has a displacement ramp, the pull plate (303f) and the unlocking plate (303g) are respectively provided with a pressing ramp, and the bottom end of the unlocking plate (303g) is provided with a limiting protrusion.

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