Air filter assembly for engine of vehicle and engineering machinery

Abstract

The utility model relates to an air filter assembly for an engine of a vehicle and engineering machinery. The air filter assembly comprises an air filter tank, a primary filter element, a secondary filter element and a self-driving device. The air filter tank is provided with an inlet and an outlet; the first-stage filter element and the second-stage filter element are arranged in the air filter tank in a spaced manner, so that the internal space of the air filter tank is divided into an upstream space, a middle space and a downstream space; the primary filter element can move between a first position and a second position, so that the upstream space is directly communicated with the intermediate space or indirectly communicated with the intermediate space through the primary filter element; the secondary filter element is fixedly arranged in the air filter tank; and the self-driving device is configured to drive the primary filter element to move between the first position and the second position according to the pressure in the downstream space. According to the air filter assembly disclosed by the utility model, the replacement and maintenance period of the first-stage filter element and the second-stage filter element can be prolonged under the condition that the air inlet resistance is reduced as much as possible.

Description

Technical Field

[0001] The utility model relates to an air filtering technology for an engine, in particular to an air filter assembly for an engine of a vehicle and an engineering machine comprising the air filter assembly. Background Art

[0002] The engine is an important and precise component in a vehicle. To avoid damage to the engine, an air filter assembly dedicated to the engine is usually provided to remove impurities that may be carried in the air that is about to enter the engine. The air filter assembly of the prior art usually includes a filter element fixedly installed in an air filter tank. The air filter assembly of a small-displacement engine generally includes a single-layer filter element, which is conducive to reducing the intake resistance, but the disadvantage is that in order to ensure the cleanliness of the air filter, the replacement cycle of the filter element is short; the air filter assembly of a large-displacement engine generally includes a double-layer filter element, thereby extending the replacement cycle of the filter element, but the disadvantage is that when the first filter element along the intake direction is severely blocked and cannot be replaced in time, a large intake resistance will be generated, thereby causing accelerated deterioration of fuel consumption and power. Utility Model Content

[0003] The purpose of the present invention is to solve at least one of the above problems and / or other problems existing in the prior art.

[0004] To achieve the above-mentioned purpose, according to one aspect of the utility model, an air filter assembly for an engine of a vehicle is provided, the air filter assembly comprising an air filter tank, a primary filter element and a secondary filter element. The air filter tank has an inlet and an outlet; the primary filter element and the secondary filter element are arranged in the air filter tank at intervals to separate the internal space of the air filter tank into an upstream space near the inlet, an intermediate space between the primary filter element and the secondary filter element, and a downstream space near the outlet. The primary filter element is arranged in the air filter tank in a manner that can move between a first position and a second position. In the first position, the upstream space is connected to the intermediate space via the primary filter element, and in the second position, the upstream space is directly connected to the intermediate space. The secondary filter element is fixedly arranged in the air filter tank. According to the utility model, the air filter assembly also includes a self-driving device, which is configured to drive the primary filter element according to the pressure in the downstream space so that the primary filter element moves between the first position and the second position.

[0005] According to one embodiment of the utility model, the primary filter element is pivotally installed in the air filter tank so as to be able to change the angle of the primary filter element relative to the central axis of the air filter tank under the drive of the self-driving device.

[0006] According to one embodiment of the utility model, the primary filter element includes a primary filter element seat, a primary filter element body installed in the primary filter element seat, and two primary filter element brackets relatively installed on the inner circumferential wall of the air filter tank, and the primary filter element seat is pivotally connected to the two primary filter element brackets, wherein, when the primary filter element is in a first position, the primary filter element seat forms a first angle with the central axis of the air filter tank, and together with the two primary filter element brackets forms a contour that fits the cross-sectional contour of the internal space of the air filter tank.

[0007] According to one embodiment of the utility model, the primary filter element seat has an arc portion and a flat portion which are respectively arranged opposite to each other, and the two primary filter element brackets each include an arc portion for abutting against the inner circumferential wall of the air filter tank and a flat surface for engaging the flat portion.

[0008] According to one embodiment of the utility model, the primary filter element seat has two relatively arranged primary filter element shafts, which are used to connect a primary filter element bracket respectively; the self-driving device is connected to the edge end of the primary filter element seat, and the primary filter element shaft is arranged offset toward the edge end relative to the center axis.

[0009] According to one embodiment of the utility model, the first-stage filter element bracket has a rotating hole for receiving the first-stage filter element shaft; the first-stage filter element seat is detachably provided with a shaft bracket, and the shaft bracket cooperates with the rotating hole to carry the first-stage filter element shaft.

[0010] According to one embodiment of the utility model, the self-driving device is configured to drive the primary filter element to a second position, in which the primary filter element seat forms a second angle with the central axis of the air filter tank, and the second angle is smaller than the first angle.

[0011] According to one embodiment of the utility model, the self-driving device includes a pressure cylinder, a push rod and a connecting rod assembly, the pressure cylinder is connected to the downstream space of the air filter tank, one end of the push rod is connected to the pressure cylinder, and the other end is connected to the edge end of the first-stage filter element seat through the connecting rod assembly.

[0012] According to one embodiment of the utility model, the pressure cylinder is arranged on the outside of the air filter tank, and the connecting rod assembly includes a first connecting rod, a second connecting rod, a third connecting rod and a fourth connecting rod which are hingedly connected in sequence, the first connecting rod is connected to the top rod in a length-adjustable manner, and the fourth connecting rod is connected to the first-stage filter element seat.

[0013] On the other hand, the utility model provides an engineering machine, which includes the air filter assembly as described above.

[0014] For the air filter assembly of the utility model, when the primary filter element is not blocked, the primary filter element is in the first position and participates in filtering the air entering the air filter tank together with the secondary filter element. After the primary filter element is blocked, the primary filter element is moved to the second position by the self-driving device so that the primary filter element does not participate in filtering, so that the air entering the air filter tank is filtered only by the secondary filter element, and the replacement and maintenance cycle of the primary filter element and the secondary filter element is extended while ensuring that the intake resistance is reduced as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The features and advantages of the present invention will be clearly understood through the detailed description provided below with reference to the accompanying drawings. It should be understood that the following drawings are merely schematic and not necessarily drawn to scale, and thus cannot be regarded as limiting the present invention, wherein:

[0016] Figure 1 A cross-sectional view of an air filter assembly according to an exemplary embodiment of the present invention is shown, wherein the primary filter element is in a first position;

[0017] Figure 2 Show Figure 1 A schematic diagram of the air filter assembly shown with the primary filter element in the second position;

[0018] Figure 3 Show Figure 1 A schematic diagram showing the components of the air filter assembly in an exploded state;

[0019] Figure 4 Show Figure 1 A cross-sectional view of the air filter assembly from another angle. DETAILED DESCRIPTION

[0020] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, many specific details are set forth so that those skilled in the art can more fully understand and implement the present invention. However, it is obvious to those skilled in the art that the implementation of the present invention may not have some of these specific details. In addition, it should be understood that the present invention is not limited to the specific embodiments described. On the contrary, any combination of the features and elements described below may be considered to implement the present invention, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims unless clearly stated in the claims.

[0021] In the following, terms such as "first", "second", etc. are used to describe the elements of the present application. These terms are only used to distinguish the various elements, and are not used to limit the nature, order or number of these elements. The terms "including" and "having" are used to express an open-ended inclusive meaning, and mean that there may be additional elements / components in addition to the listed elements / components.

[0022] Figure 1 and Figure 2 1 shows a schematic cross-sectional view of an air filter assembly according to an embodiment of the utility model, wherein the primary filter element is in a first state or first position and a second state or second position, respectively. Figure 1 and Figure 2 As shown, the air filter assembly according to this embodiment may include an air filter tank 1, a primary filter element 2, a secondary filter element 3 and a self-driving device 4. The air filter tank 1 is a cylindrical structure as a whole, and has an inlet 11 and an outlet 12 at the two axial ends of the cylindrical structure. The primary filter element 2 and the secondary filter element 3 are arranged in the air filter tank 1 in sequence and spaced apart from each other along the flow direction H of the air in the air filter tank 1 (that is, the direction from the inlet 11 to the outlet 12), and the primary filter element 2 is spaced apart from the inlet 11, and the secondary filter element 3 is spaced apart from the outlet 12, thereby dividing the internal space of the air filter tank 1 into an upstream space 13, an intermediate space 14 and a downstream space 15. The upstream space 13 is located between the primary filter element 2 and the inlet 11, the intermediate space 14 is located between the primary filter element 2 and the secondary filter element 3, and the downstream space 15 is located between the secondary filter element 3 and the outlet 12.

[0023] In the embodiment shown in the figure, the air filter tank 1 includes a tank body with a cylindrical shape and openings at both ends and two end covers respectively arranged at both ends of the tank body, and these end covers are fixed to the tank body by locking buckles. An inlet 11 is arranged in the middle of one end cover (the end cover on the right side of the figure), and an outlet 12 is arranged in the middle of the other end cover (the end cover on the left side of the figure). The inlet 11 and the outlet 12 are arranged relatively on the central axis of the tank body, and their diameters are smaller than the diameter of the tank body. Of course, the specific structure of the air filter tank 1 is not limited to the embodiment shown in the figure.

[0024] The primary filter element 2 is movably arranged in the empty filter tank 1 so as to be able to Figure 1 The first position shown is transformed to Figure 2 The second position shown. When the primary filter element 2 is in Figure 1 In the first position shown, the periphery of the primary filter element 2 is completely in contact with the inner wall of the air filter tank 1, and air can only pass through the primary filter element 2 from the upstream space 13 into the intermediate space 14. Figure 2 In the second position shown, the opposite sides of the primary filter element 2 ( Figure 1-2The upper and lower edges of the air filter cartridge 1 are separated from the inner peripheral wall of the air filter cartridge 1 to form a free air intake passage 5, so that the air in the upstream space 13 can enter the intermediate space 14 through the air intake passage 5 without passing through the primary filter cartridge 2. The secondary filter cartridge 3 is detachably fixed in the air filter cartridge 1 and remains stationary.

[0025] The self-driving device 4 can be configured to drive the primary filter element 2 according to the pressure in the downstream space 15, so that it moves from the first position toward the second position (or from the second position toward the first position), thereby making the upstream space 13 and the intermediate space 14 correspondingly switch between the two states of direct connection and connection via the primary filter element 2.

[0026] Preferably, the primary filter element 2 is pivotally mounted in the air filter tank 1, and can change its angle relative to the central axis of the air filter tank 1 under the drive of the self-driving device 4. Specifically, when the primary filter element 2 is in its first position, it forms a first angle α (the angle measured on the upstream side of the primary filter element 2 relative to the air flow direction) relative to the central axis of the air filter tank 1. The first angle α is advantageously less than 90°, which means that the primary filter element 2 is installed tilted toward the inlet 11 in its initial position (i.e., the first position). In this way, the primary filter element 2 can be driven by the self-driving device 4, for example, to rotate in a direction that reduces the first angle α, and can have a certain pre-rotation angle before rotation to prevent the upper left side and the lower right side of the primary filter element 2 from interfering with the air filter tank 1 during rotation.

[0027] Of course, the primary filter element 2 can also be installed in the air filter tank 1 in other movable ways, as long as the primary filter element 2 can be moved from a state or position that completely isolates the upstream space 13 and the middle space 14 to a state or position that allows the upstream space 13 and the middle space 14 to be freely connected.

[0028] according to Figure 3In the embodiment shown, the primary filter element 2 may include a primary filter element seat 21, a primary filter element body 22 installed in the primary filter element seat 21, and two primary filter element brackets 23 relatively installed on the inner peripheral wall of the air filter tank 1. The primary filter element seat 21 may have an oblong shape as a whole, and may include a flat portion and an arc portion respectively arranged opposite to each other. The flat portion may include two opposite straight edges, and the arc portion may include two opposite arc edges connecting the two straight edges at both ends of the two straight edges, thereby forming a concave cavity for accommodating the primary filter element body 22 as a whole. The shape of the primary filter element body 22 may be adapted to the shape of the concave cavity of the primary filter element seat 21. The two flat portions of the primary filter element seat 21 may be rotatably connected to the two primary filter element brackets 23 respectively, and may be fitted thereto when the primary filter element 2 is in the first position, thereby jointly forming a profile adapted to the cross-sectional profile of the internal space of the air filter tank 1, so that at this time, air can only enter the intermediate space 14 from the upstream space 13 through the primary filter element 2.

[0029] Continue to refer Figure 3 , wherein a primary filter element support 23 is shown, and the primary filter element support 23 can be fixed on the inner peripheral wall of the air filter tank 1, and forms a first angle α with the central axis of the air filter tank 1. The primary filter element support 23 may include an arc portion and a flat surface, and the flat surface may fit with a flat portion of the primary filter element seat 21 in a face-to-face manner. Another primary filter element support not shown may have a structure symmetrical to the illustrated primary filter element support 23, so that when the primary filter element 2 is in the first position, they and the primary filter element seat 21 (especially the arc portion thereof) together form an overall profile that fits with the inner peripheral wall of the air filter tank 1 in the entire circumferential direction.

[0030] Still refer to Figure 3 , the primary filter element support 23 may be provided with a rotation hole 231 offset toward the top side relative to the central axis on its flat surface, so as to receive the primary filter element shaft 24 correspondingly arranged on the primary filter element 2. To this end, the primary filter element 2 may include two symmetrically arranged primary filter element shafts 24, which may be respectively arranged on the two flat parts of the primary filter element seat 21. By inserting each primary filter element shaft 24 into the corresponding rotation hole 231, the primary filter element seat 21 is rotationally connected to the two primary filter element supports 23, and the self-driving device 4 is connected to the edge end of the top side (or bottom side) of the primary filter element seat 21 (for example, the top end or bottom end of one of the arc parts of the primary filter element seat 21), the self-driving device 4 can push or pull the primary filter element 2 to move it from the first position to the second position or vice versa.

[0031] Preferably, if Figure 3As shown, the rotation hole 231 on the primary filter element support 23 can be in the form of an elongated hole, which extends from the side of the primary filter element support 23 facing the inlet 11 along the axial direction and radial direction of the air filter tank 1 in at least part of the thickness of the primary filter element support 23. In this embodiment, the primary filter element 2 can also include an axis support 25 that can cooperate with the elongated hole, and the axis support 25 can have a shape and size that matches the primary filter element shaft 23, thereby carrying the primary filter element shaft 24 inserted into the elongated hole. The axis support 25 can be detachably mounted on the primary filter element seat 21, so that when the primary filter element 2 needs to be replaced, the end cover at the inlet 11 and the axis support 25 can be removed, and then the primary filter element 2 can be pulled out of the empty filter tank 1.

[0032] The secondary filter element 3 may have a similar structure to the primary filter element 2, that is, it includes a secondary filter element body, a secondary filter element seat and two secondary filter element brackets. Figure 3 As can be seen in the figure, unlike the primary filter element 2, the secondary filter element 3 includes two pairs (i.e., four) of secondary filter element shafts and two shaft brackets, which facilitates the secondary filter element 3 to be fixedly installed in the empty filter tank 1. Moreover, each secondary filter element bracket is provided with two side-by-side rotation holes.

[0033] Back to Figure 2 When the primary filter element 2 needs to be moved from the first position to the second position, for example, when the primary filter element 2 is blocked, the self-driving device 4 can push the primary filter element 2 to move the top edge of the primary filter element 2 to the right, thereby reducing the angle between the primary filter element 2 and the central axis of the empty filter tank 1, and changing the angle to a smaller second angle β. This makes the arc portion of the primary filter element seat 21 separate from the inner circumferential wall of the corresponding empty filter tank 1, thereby forming an air intake channel 5 for air to flow through between the two, so that the air can be filtered only through the secondary filter element 3, avoiding the reduction of air flow due to the blockage of the primary filter element.

[0034] Figure 4An embodiment of a self-driving device 4 is shown. The self-driving device 4 may include a pressure cylinder 41, a push rod 42, a connecting rod assembly 43 and an elastic member 44. The pressure cylinder 41 is in an integral columnar shape and has a closed cavity structure. The pressure cylinder 41 may be closed at one end by a bolt 45 screwed into the pressure cylinder 46 through a nut 46. The push rod 42 is assembled in the pressure cylinder 41 and extends from the pressure cylinder 41 at one end, and a piston portion 421 is provided at the other end, and the piston portion 421 divides the inner cavity of the pressure cylinder 41 into a rod cavity 411 and a rodless cavity 412 in the pressure cylinder 41. The rodless cavity 412 is connected to the downstream space 15 of the air filter tank 1 via a pressure pipe 6 in the form of a hose. The elastic member 44 may be a spring and is arranged in the rodless cavity 412, one end of which abuts or is connected to the axial end of the pressure cylinder 41, and the other end abuts or is connected to the piston portion 421. The elastic member 44 is slightly compressed in the initial state, and the initial position of the piston portion 421 is maintained by the elastic force of the elastic member 44 and the air pressure of the downstream space 15. One end of the connecting rod assembly 43 is connected to the end of the push rod 42 that is away from the piston portion 421, and the other end is connected to the edge end of the primary filter element seat 21. When the primary filter element 2 is blocked, the air pressure in the downstream space 15 decreases to form a negative pressure, which is transmitted to the rodless chamber 412 of the pressure cylinder 41 through the pressure tube 6, so that the piston portion 421 of the push rod 42 can move toward the direction close to the pressure tube 6 (to the left in the figure), which can further compress the elastic member 44, thereby pushing the push rod 42 and then pushing the primary filter element 2 through the connecting rod assembly 43.

[0035] like Figure 3 and Figure 4 As shown, in this embodiment, the pressure cylinder 41 is arranged on the outside of the air filter tank 1. The connecting rod assembly 43 may include a first connecting rod 431, a second connecting rod 432, a third connecting rod 433 and a fourth connecting rod 434 which are hinged in sequence. The end of the first connecting rod 431 which is away from the second connecting rod 432 is connected to the top rod 42, the third connecting rod 433 passes through the air filter tank 1, and the end of the fourth connecting rod 434 which is away from the third connecting rod 433 is connected to the edge end of the top side or the bottom side of the primary filter element seat 21.

[0036] In order to conveniently match the setting position of the pressure cylinder 41 with the position (first position and / or second position) of the primary filter element 2, as shown in FIG. Figure 3 and Figure 4 As shown, the connection end of the first connecting rod 431 with the push rod 42 is provided with an internal thread, and the connection end of the push rod 42 with the first connecting rod 431 is provided with an external thread. The self-driving device 4 may also include a locking nut 7 threadedly connected to the push rod 42. By adjusting the matching positions of the locking nut 7, the push rod 42 and the first connecting rod 431, it can be ensured that the two movable extreme positions of the piston part 421 in the pressure cylinder 41 are respectively adapted to the first position and the second position of the primary filter element 2.

[0037] The utility model also provides an engineering machine comprising the air filter assembly. The air filter assembly can be arranged at the air intake front end of the engine of the engineering machine, thereby facilitating smaller air intake resistance and longer filter element replacement cycle.

[0038] Industrial Applicability

[0039] The air filter assembly of the utility model is particularly suitable for engineering machinery with an engine. However, it should be understood that the air filter assembly can also be used for other equipment that needs to filter air, such as a motor vehicle with a gasoline engine or a diesel engine.

[0040] Below Figure 1-4 Taking the illustrated embodiment as an example, the working process of the air filter assembly according to the utility model is briefly described.

[0041] When the primary filter element body 22 of the primary filter element 2 is not blocked, during the process of air entering the air filter tank 1, the pressure of the downstream space 15 is slightly lower than the pressure of the upstream space 13, and the elastic member 44 is slightly compressed. The compression force of the elastic member 44 and the negative pressure in the air filter tank 1 generate a pre-tightening force on the primary filter element 2 through the push rod 42 and the connecting rod assembly 43, so that the primary filter element 2 is in a state as shown in FIG. Figure 1 The first position shown is in contact with the inner wall of the air filter tank 1. At this time, the air entering the upstream space 13 of the air filter tank 1 from the inlet 11 can only enter the middle space 14 through the primary filter element body 22, and enter the downstream space 15 through the secondary filter element body of the secondary filter element 3.

[0042] When the primary filter element body 22 of the primary filter element 2 is seriously blocked, the amount of air passing through the primary filter element body 22 is reduced, so that the negative pressure in the downstream space 15 of the air filter tank 1 is further increased. The increased negative pressure is transmitted to the rodless chamber 412 of the pressure cylinder 41 through the pressure pipe 6, so that the push rod 42 moves to the left side in the figure, thereby pulling the first connecting rod 431 to move to the left side. Figure 2 The second connecting rod 432 rotates counterclockwise and presses down the third connecting rod 433, so that the third connecting rod 433 rotates clockwise and can push the fourth connecting rod 434 to rotate clockwise. This pushes the primary filter element seat 21 to rotate in the direction (clockwise) that reduces the first angle α, resulting in the formation of an air intake channel 5 between the primary filter element seat 21 and the inner peripheral wall of the air filter tank 1. The air directly enters the intermediate space 14 through the air intake channel 5, and enters the downstream space 15 through the filtration of the secondary filter element body of the secondary filter element 3.

[0043] When the amount of air entering the downstream space 15 increases and the negative pressure therein is reduced to a certain extent, the top rod 42 of the self-driving device 4 can be pushed by the elastic member 44 to slightly return (i.e., to the Figure 1-2The connecting rod assembly 43 drives the primary filter element seat 21 to rotate counterclockwise, that is, to move toward the first position of the primary filter element 2 (the second angle β becomes larger at this time), causing the air inlet passage 5 to become smaller, and then reducing the amount of air entering the downstream space 15 and increasing the negative pressure therein, until equilibrium is reached again and the primary filter element 2 remains in the second position again. In this way, an adaptive control is formed.

[0044] It can be understood that the second position of the primary filter element 2 is variable, and the second position includes a plurality of position sets corresponding to different values ​​of the second angle β. In addition, the first position of the primary filter element 2 is substantially constant, and the first position corresponds to a state in which the primary filter element seat 21 is completely in contact with the primary filter element bracket 23 and the inner circumferential wall of the air filter tank 1.

[0045] exist Figure 1-4 In the illustrated embodiment, the limit position of the leftward movement of the push rod 42 can be advantageously limited by adjusting the length of the bolt 45 extending into the pressure cylinder 41, thereby limiting the limit value of the second position of the primary filter element 2, that is, the minimum value of the second angle β.

[0046] When the filter element (e.g., the primary filter element 2) of the air filter assembly according to the present invention needs to be replaced, the locking buckle can be unlocked to separate the end cover with the inlet 11 from the tank body of the air filter tank 1. Thus, the primary filter element seat 21 together with the primary filter element body 22 can be taken out from the tank body of the air filter tank 1 to replace the filter element.

[0047] As described above, according to the air filter assembly of the utility model, when the primary filter element 2 is not blocked, the primary filter element 2 is in the first position and participates in filtering the air entering the air filter tank 1 together with the secondary filter element 3. After the primary filter element 2 is blocked, the primary filter element 2 is opened by the self-driving device 4 and placed in the second position, thereby making the upstream space 13 of the air filter tank 1 directly connected with the middle space 14, and the air can enter the middle space 15 through the air intake channel 5 formed between the primary filter element 2 and the inner peripheral wall of the air filter tank 1, and the primary filter element 2 does not participate in the filtering, and the air entering the air filter tank 1 is only filtered by the secondary filter element 2, which ensures that the air intake resistance is reduced as much as possible, and the replacement and maintenance cycle of the primary filter element 2 and the secondary filter element 3 is extended.

[0048] For those skilled in the art, various modifications and variations may be made to the embodiments disclosed above without departing from the scope or spirit of the utility model. Other embodiments of the utility model will be apparent to those skilled in the art from the practice of the utility model disclosed in this specification. This specification and the examples disclosed therein should be considered to be illustrative only, and the true scope of the utility model is specified by the appended claims and their equivalents.

Claims

1. An air filter assembly for an engine of a vehicle, comprising: An empty filter tank (1), the empty filter tank (1) having an inlet (11) and an outlet (12); a primary filter element (2) and a secondary filter element (3), wherein the primary filter element (2) and the secondary filter element (3) are arranged in a spaced relationship within the empty filter tank (1) so as to divide the internal space of the empty filter tank (1) into an upstream space (13) close to the inlet (11), an intermediate space (14) between the primary filter element and the secondary filter element, and a downstream space (15) close to the outlet (12); It is characterized in that The primary filter element (2) is movably arranged in the air filter tank (1) between a first position and a second position. In the first position, the upstream space (13) is connected to the intermediate space (14) via the primary filter element (2). In the second position, the upstream space (13) is directly connected to the intermediate space (14). The secondary filter element (3) is fixedly arranged in the empty filter tank (1). The air filter assembly further comprises a self-driving device (4), wherein the self-driving device (4) is configured to drive the primary filter element (2) according to the pressure in the downstream space (15) so as to move the primary filter element (2) between a first position and a second position.

2. The air filter assembly according to claim 1, characterized in that: The primary filter element (2) is pivotally mounted in the air filter tank (1) so as to be able to change the angle of the primary filter element (2) relative to the central axis of the air filter tank (1) under the drive of the self-driving device (4).

3. The air filter assembly according to claim 2, characterized in that: The primary filter element (2) comprises a primary filter element seat (21), a primary filter element body (22) installed in the primary filter element seat (21), and two primary filter element brackets (23) relatively installed on the inner peripheral wall of the air filter tank (1), wherein the primary filter element seat (21) is pivotally connected to the two primary filter element brackets (23), wherein when the primary filter element (2) is in a first position, the primary filter element seat (21) forms a first angle (α) with the central axis of the air filter tank (1), and together with the two primary filter element brackets (23) forms a contour that fits the cross-sectional contour of the internal space of the air filter tank (1).

4. The air filter assembly according to claim 3, characterized in that: The primary filter element seat (21) has an arc portion and a flat portion which are arranged opposite to each other, and the two primary filter element brackets (23) each include an arc portion for abutting against the inner peripheral wall of the empty filter tank (1) and a flat surface for engaging with the flat portion.

5. The air filter assembly according to claim 3, characterized in that: The primary filter element seat (21) has two oppositely arranged primary filter element shafts (24) for respectively connecting to a primary filter element bracket (23); the self-driving device (4) is connected to the edge end of the primary filter element seat (21), and the primary filter element shaft (24) is arranged offset toward the edge end relative to the central axis.

6. The air filter assembly according to claim 5, characterized in that: The primary filter element support (23) has a rotation hole (231) for receiving the primary filter element shaft (24); a detachable shaft support (25) is provided on the primary filter element seat (21), and the shaft support (25) cooperates with the rotation hole (231) to carry the primary filter element shaft (24).

7. The air filter assembly according to claim 5, characterized in that: The self-driving device (4) is configured to drive the primary filter element (2) to a second position, so that in the second position, the primary filter element seat (21) forms a second angle (β) with the central axis of the air filter tank (1), and the second angle (β) is smaller than the first angle (α).

8. The air filter assembly according to claim 7, characterized in that: The self-driving device (4) comprises a pressure cylinder (41), a push rod (42) and a connecting rod assembly (43); the pressure cylinder (41) is connected to the downstream space (15) of the air filter tank (1); one end of the push rod (42) is connected to the pressure cylinder (41), and the other end is connected to the edge end of the primary filter element seat (21) through the connecting rod assembly (43).

9. The air filter assembly according to claim 8, characterized in that: The pressure cylinder (41) is arranged on the outer side of the air filter tank (1), and the connecting rod assembly (43) includes a first connecting rod (431), a second connecting rod (432), a third connecting rod (433) and a fourth connecting rod (434) which are hingedly connected in sequence, the first connecting rod (431) is connected to the top rod (42) in a length-adjustable manner, and the fourth connecting rod (434) is connected to the first-stage filter element seat (21).

10. An engineering machine, characterized in that: It comprises an air filter assembly according to any one of claims 1-9.

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