Protective cover, multi-stage air filtering system and working machine

Abstract

The utility model provides a protective cover, multistage air filtration system and operation machinery, including: a hood provided with a protective space for accommodating an air filter, the hood being provided with a mounting hole corresponding to an air inlet of the air filter, the mounting hole being shared by at least two air inlet pipes of the air filter; the movable sealing plate is movably mounted on the hood, the hood is provided with a limiting block corresponding to the mounting hole, the limiting block is used for limiting the movable sealing plate to a working position or a transportation position, a pipe passing hole is defined by the mounting hole and the movable sealing plate located at the working position, the pipe passing hole is used for allowing an air inlet pipe to pass through, and the movable sealing plate located at the transportation position seals the mounting hole. The movable sealing plate and the hood are designed to be installed in sequence instead of being integrated, installation of the air inlet pipe and the clamp can be greatly facilitated, an additional rainproof structure does not need to be added during transportation, the transportation state and the working state can be switched only by adjusting the movable sealing plate relative to the hood, and operation is easy.

Description

Technical Field

[0001] The utility model belongs to the technical field of engineering machinery, and in particular relates to a protective cover, a multi-stage air filtering system and an operating machinery. Background Art

[0002] In the multi-stage air filtration system of the excavator, the air is generally filtered by the oil bath pre-filter and then filtered by the air filter before reaching the engine. The oil bath pre-filter is large in size and the bottom needs to be frequently disassembled to replace the filter oil, so it is generally installed outside the hood body, while the air filter is generally installed inside the hood body. Therefore, when installing the intake pipe and clamp between the oil bath pre-filter and the air filter, it is necessary to operate inside the hood body to install the intake pipe and clamp inside the hood body, but the internal space of the hood body is small and the field of vision is poor, making it inconvenient to install.

[0003] In the prior art, a hole slightly larger than the outer diameter of the air intake pipe is generally directly opened on the cover body, and the air intake pipe enters the cover body through the hole to connect to the air filter. During the transportation of the excavator, the oil bath pre-filter and the air intake pipe need to be removed. If no protective measures are taken at this time, rainwater will enter the air filter through the hole in the cover body, thereby damaging the air filter. As a result, additional rain protection devices need to be added or removed during the transportation and operation of the excavator, which is complicated to operate. Utility Model Content

[0004] The main purpose of the utility model is to provide a protective cover, a multi-stage air filtering system and an operating machine, aiming to solve the technical problems in the prior art that the multi-stage air filtering system is inconvenient to install and easy to be damaged.

[0005] In order to achieve the above-mentioned purpose, the utility model provides a protective cover for a multi-stage air filtration system with an air filter, the protective cover comprising: a hood, provided with a protective space for accommodating the air filter, the hood having a mounting hole corresponding to the air inlet of the air filter, the mounting hole being used for being shared by at least two air inlet pipes of the air filter; a movable sealing plate movably mounted on the hood, the hood having a limiting block corresponding to the mounting hole, the limiting block being used for limiting the movable sealing plate to a working position or a transport position, the mounting hole and the movable sealing plate located at the working position forming a pipe through hole, the pipe through hole being used for the air inlet pipe to pass through, and the movable sealing plate located at the transport position sealing the mounting hole.

[0006] In an embodiment of the utility model, the movable covering plate includes a plate body and a limiting column arranged at the bottom of the plate body, and the hood also includes a crossbeam installed in the mounting hole, the crossbeam is provided with a limiting groove for the limiting column to extend into, the limiting block is located in the limiting groove and is provided with a rotation notch for limiting the limiting column.

[0007] In an embodiment of the utility model, an operating handle is arranged on the top of the plate body, and the limiting column is arranged corresponding to the end of the operating handle.

[0008] In an embodiment of the utility model, the movable sealing plate further comprises a limiting plate connected to the limiting column, and the limiting plate is provided with a limiting surface for contacting with the limiting block surface.

[0009] In an embodiment of the utility model, the protective cover also includes a locking gasket which is sleeved on the outside of the limit column, and a lock hole for inserting a locking pin is provided at one end of the limit column away from the movable sealing plate, and the locking gasket is used to abut against the limit block and the limit plate under the pressure of the locking pin.

[0010] In an embodiment of the utility model, the movable sealing plate includes an inner recess and an outer protrusion. The inner recess located at the working position cooperates with the mounting hole to form the pipe hole, and the outer protrusion located at the transport position seals the mounting hole. The number of the inner recesses is used to correspond to the number of the intake pipes, and the number of the inner recesses is consistent with the number of the outer protrusions.

[0011] In an embodiment of the utility model, the movable covering plate is used to be connected to the hood through a connecting piece, and a first opening groove and a second opening groove are provided on the movable covering plate. The first opening groove located in the working position is clamped with the connecting piece, and the second opening groove located in the transport position is clamped with the connecting piece.

[0012] The utility model also provides a multi-stage air filtration system, which includes a pre-filter, an air filter and the protective cover as described above, and the air inlet of the air filter is connected to the pre-filter through an air inlet pipe.

[0013] In an embodiment of the utility model, the multi-stage air filtration system further comprises a protective sleeve, which is snap-fitted into the pipe hole and used to protect the air intake pipe.

[0014] The utility model also provides an operating machine, which comprises the multi-stage air filtering system as described above.

[0015] Through the above technical solution, the protective cover provided by the embodiment of the utility model has the following beneficial effects:

[0016] When a protective cover is used to assemble a multi-stage air filtration system, the hood, air filter, and pre-filter are first fixed, the air filter is installed in the protective space of the hood, the pre-filter is installed outside the hood, and then the air filter and the pre-filter are connected with an air intake pipe, and finally the air intake pipe is fixed with a clamp. One mounting hole is shared by at least two air intake pipes. Compared with the method of opening a hole for each air intake pipe separately in the prior art, the size of the mounting hole can be larger, which is convenient for the hand to directly enter the protective space from above to assemble the air intake pipe and the clamp. When the multi-stage air filtration system needs to work, a movable sealing plate can be installed, and the limit block on the hood can limit the movable sealing plate to the working position, so that the movable sealing plate and the hole wall of the mounting hole form a pipe hole for the air intake pipe to pass through. When the multi-stage air filtration system needs to be transported, the pre-filter and the air intake pipe can be removed, and the movable sealing plate can be rotated relative to the hood to the transportation position, so that the limit block limits the movable sealing plate to the transportation position, and the movable sealing plate completely seals the mounting hole, which can prevent rainwater from entering the air filter. The movable sealing plate and the hood in the utility model are designed to be installed one after the other rather than as one piece, which greatly facilitates the installation of the air intake pipe and the clamp. During installation, the hand can directly enter the protective space inside the hood from above through the installation hole to assemble the air intake pipe and the clamp. There is enough space and no other parts to block it, which is convenient for installation. No additional rainproof structure is required during transportation. Only the movable sealing plate needs to be adjusted relative to the hood to switch between the transportation and working states, which is simple to operate.

[0017] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the accompanying drawings:

[0019] Figure 1 It is a partial schematic diagram of a multi-stage air filtration system according to one embodiment of the utility model;

[0020] Figure 2 It is a schematic diagram of the working state structure of a multi-stage air filtration system according to one embodiment of the utility model;

[0021] Figure 3 It is a schematic diagram of the transport state structure of a multi-stage air filtration system according to one embodiment of the utility model;

[0022] Figure 4 It is a partial structural schematic diagram of a protective cover according to an embodiment of the utility model;

[0023] Figure 5 It is a schematic diagram of the cross-sectional structure of a protective cover according to one embodiment of the utility model;

[0024] Figure 6 It is a schematic structural diagram of a movable sealing plate of a protective cover in one embodiment of the utility model at a certain viewing angle;

[0025] Figure 7 It is a schematic structural diagram of the movable sealing plate of the protective cover in one embodiment of the utility model under another viewing angle.

[0026] Description of Reference Numerals

[0027] Label Name Label Name

[0028] 100 protective cover 25 outer convex part

[0029] 1 Hood 26 First opening slot

[0030] 11 Protective space 27 Second opening slot

[0031] 12 Mounting hole 3 Locking washer

[0032] 121 waist hole arc 4 connector

[0033] 13 Limit block 5 Lock pin

[0034] 14 Beam 200 Multi-stage Air Filtration System

[0035] 141 Limiting groove 210 Air filter

[0036] 2 Movable sealing plate 220 Pre-filter

[0037] 21 Limiting column 230 Intake pipe

[0038] 22 Operating handle 240 Clamp

[0039] 23 limit plate 250 protective cover

[0040] 24 Concave part DETAILED DESCRIPTION

[0041] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] The protective cover according to the present invention is described below with reference to the accompanying drawings.

[0043] like Figures 1 to 7As shown, a multi-stage air filtration system 200 with an air filter 210, the protective cover 100 includes a hood 1 and a movable sealing plate 2, the hood 1 is provided with a protective space 11 for accommodating the air filter 210, the hood 1 is provided with a mounting hole 12 corresponding to the air inlet of the air filter 210, the mounting hole 12 is used for being shared by at least two air inlet pipes 230 of the air filter 210; the movable sealing plate 2 is movably mounted on the hood 1, the hood 1 is provided with a limiting block 13 corresponding to the mounting hole 12, the limiting block 13 is used to limit the movable sealing plate 2 to a working position or a transport position, the mounting hole 12 and the movable sealing plate 2 located at the working position form a pipe through hole, the pipe through hole is used for the air inlet pipe 230 to pass through, and the movable sealing plate 2 located at the transport position seals the mounting hole 12.

[0044] It can be understood that the protective cover 100 in this embodiment is mainly used for the multi-stage air filtration system 200 of the excavator. The pre-filter 220 of the multi-stage air filtration system 200 can be connected to the air inlet of the air filter 210 through the air inlet pipe 230. The pre-filter 220 and the air filter 210 can both adopt the air filtration structure in the prior art. The number of air inlets can be set according to actual use requirements. The number of air inlet pipes 230 is consistent with the number of air inlets and is connected one by one. The pre-filter 220 can be installed outside the hood 1, and a clamp 240 for fixing the air inlet pipe 230 can be provided in the protective space 11.

[0045] When the protective cover 100 in this embodiment is used to assemble the multi-stage air filtration system 200, the hood 1, the air filter 210, and the pre-filter 220 are first fixed, the air filter 210 is installed in the protective space 11 of the hood 1, and the pre-filter 220 is installed outside the hood 1, and then the air filter 210 and the pre-filter 220 are connected by the air intake pipe 230, and finally the air intake pipe 230 is fixed by the clamp 240. One mounting hole 12 is shared by at least two air intake pipes 230. Compared with the method of opening a hole for each air intake pipe 230 separately in the prior art, the size of the mounting hole 12 can be larger, which is convenient for the hand to directly enter the protective space 11 from above to assemble the air intake pipe 230 and the clamp 240. When the multi-stage air filtration system 200 needs to work, the movable sealing plate 2 can be installed, and the limit block 13 on the hood 1 can limit the movable sealing plate 2 to the working position, so that the movable sealing plate 2 and the hole wall of the mounting hole 12 form a through-hole for the air intake pipe 230 to pass through. When the multi-stage air filtration system 200 needs to be transported, the pre-filter 220 and the air intake pipe 230 can be removed, and the movable sealing plate 2 can be rotated to the transportation position relative to the hood 1, so that the limit block 13 limits the movable sealing plate 2 to the transportation position, and the movable sealing plate 2 completely seals the mounting hole 12, which can prevent rainwater from entering the air filter 210. The movable sealing plate 2 and the hood 1 in this embodiment are designed to be installed one after another rather than as a whole, which can greatly facilitate the installation of the air intake pipe 230 and the clamp 240. During installation, the hand can directly enter the protective space 11 inside the hood 1 from above through the mounting hole 12 to assemble the air intake pipe 230 and the clamp 240. There is enough space and no other parts blocking it, which is convenient for installation. There is no need to add additional rainproof structure during transportation. You only need to adjust the movable cover plate 2 relative to the machine cover 1 to switch between the transportation and working states. The operation is simple.

[0046] In one embodiment, the movable cover plate 2 includes a plate body and a limiting column 21 disposed at the bottom of the plate body, the hood 1 also includes a crossbeam 14 installed in the mounting hole 12, the crossbeam 14 is provided with a limiting groove 141 for the limiting column 21 to extend into, the limiting block 13 is located in the limiting groove 141 and is provided with a rotation notch for limiting the limiting column 21. Figures 1 to 4 As shown, the mounting hole 12 in this embodiment is in the shape of an elongated strip, the crossbeam 14 is located in the spatial position of the mounting hole 12, and penetrates the mounting hole 12 in the front-to-back direction, the limiting groove 141 is opened in the middle of the crossbeam 14, and the limiting groove 141 and the limiting column 21 match in shape, the limiting column 21 can be cylindrical, the limiting block 13 can abut the limiting column 21, and the length of the limiting column 21 is greater than the depth of the limiting groove 141, and the limiting column 21 can penetrate the limiting groove 141. The limiting column 21 is located at the center of the movable sealing plate 2, and the movable sealing plate 2 can be adjusted relative to the hood 1 by rotation, so that the limiting column 21 is always located in the limiting groove 141.

[0047] In one embodiment, an operating handle 22 is provided on the top of the plate body, and the limiting column 21 is provided corresponding to the end of the operating handle 22. The plate body is a centrally symmetrical structure, the operating handle 22 is on one side of the plate body, and the limiting column 21 is located on the other side of the plate body. The operating handle 22 exposed to the hood 1 can be easily operated by hand, and the cross section of the operating handle 22 is U-shaped. The limiting column 21 provided corresponding to the operating handle 22 can facilitate the operator to visually grasp the position of the limiting column 21, thereby judging whether the limiting column 21 is inserted into the limiting groove 141.

[0048] like Figures 4 to 7 As shown, the movable sealing plate 2 also includes a limiting plate 23 connected to the limiting column 21, and the limiting plate 23 is provided with a limiting surface for contacting the limiting block 13. The limiting plate 23 is in the shape of a thin plate, and the limiting surface can contact the limiting block 13, ensuring the contact area between the limiting plate 23 and the limiting block 13, and improving the limiting stability. The limiting plate 23 in this embodiment is provided with a 90-degree rotation notch, which can make the movable sealing plate 2 only rotate 90 degrees, and the starting position and the end position of the rotation of the movable sealing plate 2 correspond to the two functions of the movable sealing plate 2. The limiting plate 23, the operating handle 22 and the limiting column 21 can be integrally formed into the movable sealing plate 2, and the limiting plate 23, the operating handle 22 and the limiting column 21 move synchronously. By rotating the operating handle 22, the limiting plate 23 on the operating handle 22 can be limited by the limiting block 13 in the direction and range of rotation, so that the plate body can only rotate 90 degrees.

[0049] Specifically, the protective cover 100 further includes a locking washer 3 sleeved outside the limiting column 21, and a locking hole for inserting a locking pin 5 is provided at one end of the limiting column 21 away from the movable sealing plate 2, and the locking washer 3 is used to abut against the limiting block 13 and the limiting plate 23 under the pressure of the locking pin 5. After the rotation center axis of the operating handle 22 is inserted into the limiting groove 141 on the crossbeam 14, the locking washer 3 and the locking pin 5 can be installed in sequence from top to bottom at the lower end of the limiting column 21, so that the locking washer 3 abuts against the limiting block 13 and the limiting plate 23 at the same time under the pressure of the locking pin, thereby improving the connection stability of the hood 1 and the movable sealing plate 2.

[0050] In one embodiment, the movable sealing plate 2 includes an inner concave portion 24 and an outer convex portion 25. The inner concave portion 24 located at the working position cooperates with the mounting hole 12 to enclose the pipe hole, and the outer convex portion 25 located at the transport position seals the mounting hole 12. The number of the inner concave portions 24 is used to correspond to the number of the intake pipes 230, and the number of the inner concave portions 24 and the outer convex portions 25 are the same. Figures 1 to 3 As shown, Figure 2 The multi-stage air filtration system 200 is in working condition. Figure 3The multi-stage air filtration system 200 is in the transport state, the number of the inner recess 24 and the outer protrusion 25 are both two, and the inner recess 24 and the outer protrusion 25 are arranged crosswise with each other. When the state conversion is required, only the movable cover plate 2 needs to be rotated. The half-concave and half-convex structure of the movable cover plate 2 enables it to be used in both the working and transport states of the multi-stage air filtration system 200. In other embodiments, the number of the inner recess 24 and the outer protrusion 25 can be set according to actual use requirements.

[0051] like Figure 1 As shown, the mounting hole 12 is a waist hole with a waist hole arc 121, and the center of the waist hole arc 121 is used to correspond to the axis of the air inlet. In this embodiment, the mounting hole 12 is located at the top of the hood 1, and the number of air inlets is two. The two ends of the mounting hole 12 in the length direction are provided with waist hole arcs 121. The distance between the centers of the waist hole arcs 121 is equal to the distance between the axes of the two air inlets. The diameter of the waist hole arc 121 is larger than the outer diameter of the air inlet pipe 230, which can facilitate the connection between the movable sealing plate 2 and the hood 1. In this embodiment, through a large waist hole, it is convenient for the hand to directly reach into the interior of the hood 1 from above to assemble the air inlet pipe 230 and the clamp 240.

[0052] like Figure 6 As shown, the movable cover plate 2 is used to connect with the hood 1 through the connecting member 4. The movable cover plate 2 is provided with a first opening groove 26 and a second opening groove 27. The first opening groove 26 located at the working position clamps the connecting member 4, and the second opening groove 27 located at the transport position clamps the connecting member 4. The connecting member 4 in this embodiment may be a bolt or a screw, and the hood 1 may be provided with a threaded hole. The connecting member 4 and the hood 1 are threadedly connected. The first opening groove 26 and the second opening groove 27 are both arc-shaped grooves and are symmetrically arranged along the center line of the movable cover plate 2. During the rotation of the movable cover plate 2 relative to the hood 1, the connecting member 4 is fixed relative to the hood 1, and can be switched back and forth in the first opening groove 26 and the second opening groove 27 through the inner recess 24. When the multi-stage air filtration system 200 needs to change its state, for example, from a working state to a transport state, or from a transport state to a working state, the movable cover plate 2 is rotated, and the connecting member 4 does not need to be removed. The connecting member 4 only needs to be loosened to form a movable space between the connecting member 4 and the hood 1 for the movable cover plate 2 to pass through. After the rotation is completed, the bolts can be tightened, which can facilitate the state conversion operation.

[0053] The utility model also proposes a multi-stage air filtration system 200, which includes a pre-filter 220, an air filter 210 and the protective cover 100 as described above, and the air inlet of the air filter 210 is connected to the pre-filter 220 through an air inlet pipe 230. The pre-filter 220 in this embodiment is installed outside the protective cover 100, and the air filter 210 is installed in the protective space 11. The pre-filter 220 and the air filter 210 can be connected through the air inlet pipe 230. The specific structure of the protective cover 100 refers to the above embodiment. Since the multi-stage air filtration system 200 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0054] In the embodiment of the utility model, the multi-stage air filtration system 200 further includes a protective sleeve 250, which is clamped in the pipe hole and used to protect the air intake pipe 230. The protective sleeve 250 in this embodiment can be a flexible sleeve. When the multi-stage air filtration system 200 is in a working state, the protective sleeve 250 is clamped in the pipe hole and sleeved on the outside of the air intake pipe 230, which can prevent the air intake pipe 230 from colliding or wearing with the hood 1 and the movable sealing plate 2 due to vibration.

[0055] The utility model also provides a working machine, the working machine includes the multi-stage air filtration system 200 as described above, and the specific structure of the multi-stage air filtration system 200 refers to the above embodiment. Since the working machine adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here. In one embodiment, the working machine can be an excavator with a multi-stage air filtration system 200.

[0056] In the description of the present invention, it should be understood that the terms "first" and "second" 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 the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0057] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; 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 the present invention can be understood according to specific circumstances.

[0058] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0059] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A protective cover for a multi-stage air filtration system (200) with an air filter (210), characterized in that: The protective cover (100) comprises: A hood (1) is provided with a protective space (11) for accommodating the air filter (210); the hood (1) is provided with a mounting hole (12) corresponding to an air inlet of the air filter (210); the mounting hole (12) is used for being shared by at least two air inlet pipes (230) of the air filter (210); A movable sealing plate (2) is movably mounted on the hood (1); a limit block (13) is provided on the hood (1) corresponding to the mounting hole (12); the limit block (13) is used to limit the movable sealing plate (2) to a working position or a transport position; the mounting hole (12) and the movable sealing plate (2) at the working position form a pipe hole; the pipe hole is used for the air intake pipe (230) to pass through; the movable sealing plate (2) at the transport position seals the mounting hole (12).

2. The protective cover according to claim 1, characterized in that: The movable sealing plate (2) includes a plate body and a limiting column (21) arranged at the bottom of the plate body, and the hood (1) also includes a crossbeam (14) installed in the installation hole (12), and the crossbeam (14) is provided with a limiting groove (141) for the limiting column (21) to extend into, and the limiting block (13) is located in the limiting groove (141) and is provided with a rotation notch for limiting the limiting column (21).

3. The protective cover according to claim 2, characterized in that: An operating handle (22) is arranged on the top of the plate body, and the limiting column (21) is arranged corresponding to the end of the operating handle (22).

4. The protective cover according to claim 2, characterized in that: The movable sealing plate (2) further comprises a limiting plate (23) connected to the limiting column (21), and the limiting plate (23) is provided with a limiting surface for surface contact with the limiting block (13).

5. The protective cover according to claim 4, characterized in that: The protective cover (100) also includes a locking gasket (3) sleeved on the outside of the limiting column (21), and a locking hole for inserting a locking pin (5) is provided at one end of the limiting column (21) away from the movable sealing plate (2), and the locking gasket (3) is used to abut the limiting block (13) and the limiting plate (23) under the pressure of the locking pin (5).

6. The protective cover according to any one of claims 1 to 5, characterized in that: The movable sealing plate (2) includes an inner recess (24) and an outer protrusion (25). The inner recess (24) located in the working position cooperates with the mounting hole (12) to form the pipe hole, and the outer protrusion (25) located in the transport position seals the mounting hole (12). The number of the inner recess (24) is used to correspond to the number of the intake pipes (230), and the number of the inner recess (24) and the number of the outer protrusion (25) are consistent.

7. The protective cover according to any one of claims 1 to 5, characterized in that: The movable cover plate (2) is used to be connected to the hood (1) via a connecting piece (4); a first opening groove (26) and a second opening groove (27) are provided on the movable cover plate (2); the first opening groove (26) located at the working position is clamped to the connecting piece (4), and the second opening groove (27) located at the transport position is clamped to the connecting piece (4).

8. A multi-stage air filtration system, characterized in that: The multi-stage air filtration system (200) comprises a pre-filter (220), an air filter (210) and the protective cover (100) according to any one of claims 1 to 7, and an air inlet of the air filter (210) is connected to the pre-filter (220) via an air inlet pipe (230).

9. The multi-stage air filtration system according to claim 8, characterized in that: The multi-stage air filtration system (200) further comprises a protective sleeve (250), wherein the protective sleeve (250) is snap-fitted into the pipe hole and is used to protect the air intake pipe (230).

10. A working machine, characterized in that: The working machine comprises the multi-stage air filtration system (200) according to claim 8 or 9.

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