CN219531085U - Coarse filtering mechanism of fresh air system - Google Patents

Abstract

The utility model relates to a coarse filtering mechanism of a fresh air system, and belongs to the technical field of fresh air systems. The rough filtering mechanism of the fresh air system comprises a housing, a mounting plate, rough filtering units and limiting components, wherein the mounting plate is arranged in the housing and is provided with a plurality of mounting openings, each mounting opening is detachably embedded with the rough filtering unit, at least two opposite angles of each rough filtering unit are limited by the limiting components, the limiting components are rotatably arranged on the mounting plate and used for pressing the angles of the rough filtering units, and the rough filtering units can be locked or unlocked in the rotation process of the limiting components. According to the coarse filtering mechanism of the fresh air system, provided by the utility model, the plurality of independent coarse filtering units are used for filtering, each coarse filtering unit is limited by the limiting component, and the limiting component can limit or release the limitation of the coarse filtering unit when moving, so that the coarse filtering unit is overhauled, replaced, cleaned and the like, the maintenance cost can be reduced, and the operation is simple and convenient.

Description

Coarse filtering mechanism of fresh air system

Technical Field

The utility model belongs to the technical field of fresh air systems, and particularly relates to a coarse filtering mechanism of a fresh air system.

Background

In large places such as markets and supermarkets, a large fresh air system is needed to be used, external air enters the room after being filtered, and indoor dirty air is discharged through an exhaust system, for example, the patent number is CN201620073726.2, the patent of the utility model named as a hybrid fresh air machine and the patent number is CN202020424740.9, the utility model of the utility model named as a self-cleaning fresh air device of a filter screen is generally of a whole structure, the area is large, the whole filter screen needs to be detached during replacement, the space of the fresh air system is relatively narrow, the replacement is troublesome, and particularly, a coarse filter mechanism is replaced and cleaned frequently.

Disclosure of Invention

In view of the above, the present utility model aims to provide a coarse filtration mechanism of a fresh air system, which filters by a plurality of independent coarse filtration units, wherein each coarse filtration unit is limited by a limiting component, and the limiting component can limit or release the limiting of the coarse filtration unit when moving, so that the coarse filtration unit is overhauled, replaced, cleaned, etc., and the maintenance cost can be reduced, and the operation is simple and convenient.

The technical scheme of the utility model is as follows:

the utility model provides a coarse filtering mechanism of a fresh air system, which comprises a housing, a mounting plate, coarse filtering units and limiting components, wherein the mounting plate is arranged in the housing and is provided with a plurality of mounting openings, each mounting opening is detachably embedded with the coarse filtering unit, at least two opposite corners of each coarse filtering unit are limited by the limiting components, the limiting components are rotatably arranged on the mounting plate and are used for pressing the corners of the coarse filtering units, and the coarse filtering units can be locked or unlocked in the rotation process of the limiting components.

As an alternative to the above embodiments, the limiting assembly includes a limiting shaft rotatably and axially slidably disposed on the mounting plate, the limiting shaft being disposed adjacent to an angle of the coarse filter unit, a limiting head fixed to the limiting shaft so that the limiting head can be moved closer to or farther from the coarse filter unit, and a limiting spring sleeved on the limiting shaft and having a tendency to move closer to the coarse filter unit.

As an alternative to the foregoing embodiment, the limiting shaft penetrates through the mounting plate, the limiting shaft includes a first end and a second end that are located at two sides of the mounting plate, the limiting head is fixedly connected with the first end, and two ends of the limiting spring are respectively abutted to the second end and the mounting plate.

As an alternative to the above embodiment, the second end of the limiting shaft is provided with a threaded section and a limiting member, the limiting member is in threaded engagement with the threaded section, two ends of the limiting spring are respectively abutted against the limiting member and the mounting plate, and the position of the limiting member on the limiting shaft is adjustable so as to change the pretightening force of the limiting spring.

As an alternative to the above embodiment, the limiting head is disposed in a V-shape, and both end portions of the limiting head are bent toward the coarse filtration unit so as to extend into the mounting opening and abut against the coarse filtration unit.

As an alternative to the above embodiments, the defining head further comprises a pull ring, which is provided at one side of the defining head, to enable a user to pull the defining head to move.

As an alternative to the above embodiments, the housing includes a case and an access door, one side of the housing is provided with an access opening, and the access door is movably provided to the housing and is used to open or close the access opening.

As an alternative to the above embodiment, the inner side of each mounting opening is provided with a step, and the coarse filtration unit includes a frame, and the frame is embedded in the mounting opening and abuts against the step.

As the alternative scheme of above-mentioned embodiment, coarse filtration unit still includes the silica gel strip, all be provided with around the frame the silica gel strip, the silica gel strip is followed the edge of frame stretches out, so that the frame embedding when the installing port, the silica gel strip warp and with the laminating of the internal surface of installing port.

As an alternative to the above embodiment, the coarse filtration unit further includes a filtration member, the filtration member is disposed on one side of the frame, the filtration member includes a plurality of filtration bags, the plurality of filtration bags are vertically flat and distributed side by side, and the openings of the filtration bags face outwards.

The beneficial effects of the utility model are as follows:

according to the coarse filtering mechanism of the fresh air system, provided by the utility model, the plurality of independent coarse filtering units are used for filtering, each coarse filtering unit is limited by the limiting component, and the limiting component can limit or release the limitation of the coarse filtering unit when moving, so that the coarse filtering unit is overhauled, replaced, cleaned and the like, the maintenance cost can be reduced, and the operation is simple and convenient.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. The above and other objects, features and advantages of the present utility model will become more apparent from the accompanying drawings. Like reference numerals refer to like parts throughout the several views of the drawings. The drawings are not intended to be drawn to scale, with emphasis instead being placed upon illustrating the principles of the utility model.

Fig. 1 is a schematic structural diagram of a coarse filtering mechanism of a fresh air system according to an embodiment of the present utility model;

fig. 2 is a schematic structural diagram II of a coarse filtering mechanism of a fresh air system according to an embodiment of the present utility model;

fig. 3 is a schematic structural diagram III of a coarse filtering mechanism of a fresh air system according to an embodiment of the present utility model;

FIG. 4 is a cross-sectional view A-A of FIG. 3;

FIG. 5 is a schematic structural view of a mounting plate of a coarse filtration mechanism according to an embodiment of the present utility model;

fig. 6 is a schematic structural diagram of a coarse filtration unit of the coarse filtration mechanism according to an embodiment of the present utility model;

fig. 7 is a schematic diagram of a coarse filtration unit of a coarse filtration mechanism according to a second embodiment of the present utility model;

FIG. 8 is a schematic diagram of a defining assembly of a coarse filtration mechanism according to an embodiment of the present utility model;

FIG. 9 is a schematic diagram II of a defining assembly of a coarse filtration mechanism according to an embodiment of the present utility model;

fig. 10 is a B-B cross-sectional view of fig. 9.

Icon: 10-a coarse filtration mechanism; 11-a housing; 12-mounting plates; 13-a coarse filtration unit; 14-defining an assembly; 110-a housing; 111-access door; 112-an access port; 120-mounting port; 121-steps; 130-frame; 131-a filter; 132-a silica gel strip; 140-defining an axis; 141-defining a head; 142-define a spring; 143-a bend; 144-thread segments; 145-defining piece.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

Furthermore, the terms "first," "second," and the like, are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

Referring to fig. 1-4, an embodiment of the present utility model provides a coarse filtering mechanism 10 of a fresh air system, where the fresh air system is mainly used in places such as markets, and the coarse filtering mechanism 10 is used as a part of the fresh air system, and is mainly used for primarily filtering air flow, so as to filter impurities such as particles in the air flow, and in addition, the fresh air system may further include a fine filtering mechanism, a fan module, and the like. The novel air system is mainly used for air intake, the front end of the novel air system can be communicated with an air intake pipeline, the air intake pipeline is communicated with the outside, the rear end of the novel air system can be communicated with an indoor pipeline, and when the novel air system works, the outside air can be introduced into the indoor pipeline through the air intake pipeline. The exhaust of indoor air can be realized through an exhaust system to realize indoor air exchange, and of course, the exhaust system and the fresh air system of the embodiment are independent two parts.

The coarse filtration mechanism 10 is mainly composed of a housing 11, a mounting plate 12, a coarse filtration unit 13, and a limiting assembly 14, and the structure of each part is discussed in detail below.

The casing 11 functions to form an air flow passage, and the shape of the casing 11 is not limited, and may be, for example, a circular tubular structure or the like, and in this embodiment, the casing 11 adopts a rectangular tubular structure with an air flow passage inside.

The dimensions of the housing 11 may be set as required, and may be large or small, and in general, the height of the housing 11 may be about 2m in a fresh air system used in places such as a mall. The housing 11 includes a case 110 and an access door 111, one side of the housing 11 is provided with an access port 112, and the access door 111 is movably provided to the housing 11 and is used to open or close the access port 112. After the user closes the access door 111, the access door 112 may be closed by using a lock or a latch, thereby forming a closed air flow channel; after the user opens the access door 111, the user can perform maintenance, replacement, and the like for the national rating system and the like inside the housing 11.

The mounting plate 12 is provided in the housing 11, the air flow passage is divided into two areas by the mounting plate 12, the mounting plate 12 may be made of steel plate, aluminum alloy plate, or the like, and the thickness of the mounting plate 12 is not limited.

Referring to fig. 5, the mounting plate 12 has a plurality of mounting openings 120, and the openings 120 can communicate two regions of the airflow path to allow airflow from one region to another region through the openings 120. The shape of the mounting port 120 is not limited, and for example, the mounting port 120 is a square hole, a circular hole, or the like, and in this embodiment, the mounting port 120 is a square hole. In this embodiment, the arrangement manner of the plurality of mounting ports 120 may be rectangular array distribution, however, in other embodiments, the plurality of mounting ports 120 may be arranged in other manners.

Each mounting opening 120 is correspondingly provided with a coarse filtration unit 13, and the coarse filtration unit 13 is detachably embedded in the corresponding mounting opening 120, and the coarse filtration unit 13 and the mounting opening 120 may be embedded in the following manner, but not limited to: the inner side of each mounting opening 120 is provided with a step 121, the step 121 is recessed inwards, and as shown in fig. 6 and 7, the coarse filtration unit 13 comprises a frame 130 and a filtration member 131, and the filtration member 131 is arranged on one side of the frame 130. After the coarse filtration unit 13 is embedded in the mounting opening 120, the frame 130 is embedded in the mounting opening 120 and is abutted against the step 121, the step 121 can limit the front and rear movable range of the frame 130, and the periphery of the mounting opening 120 can limit the movable range of the frame 130 towards the periphery.

The air flow may be via the filter bag, and in order to prevent the air flow from passing through the gap between the rim 130 and the mounting port 120, in some embodiments, the following technical scheme may be adopted: the coarse filtration unit 13 further comprises a silica gel strip 132, the silica gel strip 132 is arranged around the frame 130, and the silica gel strip 132 extends out from the edge of the frame 130, so that when the frame 130 is embedded into the mounting opening 120, the silica gel strip 132 deforms and is attached to the inner surface of the mounting opening 120.

The installation manner of the silica gel strip 132 and the frame 130 can adopt, but is not limited to, the following schemes: the frame 130 includes four framework, and four framework are rectangle head and tail connection, and every framework all is provided with the mounting groove of bar, and the cross-section of mounting groove can be T shape, and silica gel strip 132 is rectangular shape and has certain width, and in the mounting groove was located in slidable ground in one side of silica gel strip 132, a portion of silica gel strip 132 stretches out from the mounting groove. The silica gel strip 132 can elastically deform, when the frame 130 is installed at the installation opening 120, because the silica gel strip 132 is closer to the side wall of the installation opening 120 relative to the frame 130, the silica gel strip 132 contacts with the side wall of the installation opening 120 and elastically deforms, so that the silica gel strip 132 completely seals the gap between the frame 130 and the installation opening 120, prevents the air flow from passing through the gap, and ensures that the air flow is sufficiently filtered.

The filter 131 may have a structure in the prior art, for example, the filter 131 may have a plate-like structure, or the following scheme may be adopted: the filter member 131 includes a plurality of filter bags, which may be paper bags, filter screens, or the like. The filter bag is vertically flat, vertical setting makes the filter bag be difficult for sagging, and a plurality of filter bag distributes side by side, and the opening of filter bag outwards, and the flow direction of air current is used for the standard, and the air current can get into in the filter bag from the opening promptly towards the upper reaches opening of air current to the filter bag.

The coarse filter units 13 are replaced and cleaned more frequently, and if conventional fixing means such as bolting are used, the disassembly and assembly are complicated, and in this embodiment, the coarse filter units 13 are rectangular overall, and at least two opposite corners of each coarse filter unit 13 are defined by the defining components 14, for example, two opposite corners of the coarse filter unit 13 are defined by the defining components 14, or three or four corners of the coarse filter unit 13 are defined by the defining components 14. The limiting assembly 14 is rotatably disposed on the mounting plate 12, and the limiting assembly 14 has different states during rotation: the limiting assembly 14 presses the corners of the rim 130 of the coarse filter unit 13, locking the coarse filter unit 13, and the coarse filter unit 13 cannot be detached from the mounting opening 120; the restricting assembly 14 is disengaged from the rim 130 of the coarse filter unit 13 to unlock the coarse filter unit 13, and the coarse filter unit 13 is detachable from the mounting opening 120. The coarse filtration unit 13 can be locked or unlocked by manually controlling the limiting assembly 14 to rotate, and the operation is simple and convenient, and time and labor are saved.

The structure of the limiting assembly 14 is not limited, and in this embodiment, the following may be adopted, but not limited to: referring to fig. 8-10, the limiting assembly 14 includes a limiting shaft 140, a limiting head 141, and a limiting spring 142.

The defining shaft 140 may have a rod-like structure, and the defining shaft 140 penetrates the mounting plate 12 in the thickness direction of the mounting plate 12, and the defining shaft 140 has a first end and a second end, wherein the first end and the second end are located at both sides of the mounting plate 12, respectively, the first end being located upstream, and the second end being located downstream.

Each limiting assembly 14 is arranged adjacent to one of the corners of one coarse filtration unit 13, the mounting plate 12 is provided with a mounting hole, the mounting hole is a round hole, the limiting shaft 140 is a round rod, the limiting shaft 140 is inserted into the mounting hole, the limiting shaft 140 can rotate around the axis of the limiting shaft 140 and can slide axially along the limiting shaft 140, the structure is common, the first end and the second end can limit the moving range of the limiting shaft 140 in the axial sliding process of the limiting shaft 140, for example, the first end and the second end are both provided with limiting parts, and the diameter of the limiting parts is larger than that of the mounting hole.

The limiting head 141 and the limiting shaft 140 are fixed, and the connection manner of the limiting head 141 and the limiting shaft 140 is not limited, for example, the limiting head 141 and the limiting shaft 140 are integrally formed, welded and fixed, etc., so that the limiting head 141 can move along with the limiting shaft 140, and when the limiting shaft 140 drives the limiting head 141 to slide along the axial direction, the limiting head 141 can be close to or far away from the coarse filtration unit 13. When the defining head 141 approaches the coarse filtration unit 13, the defining head 141 can press the rim 130; when the defining head 141 is distanced from the coarse filter unit 13, the defining head 141 can be rotated about the axis of the defining shaft 140, so that the defining head 141 can be rotated to a position that does not interfere with removal of the rim 130, and thus the coarse filter unit 13 can be removed from the mounting opening 120. After the new coarse filtration unit 13 is replaced or the cleaning is completed, the limiting head 141 may be rotated reversely, so that the limiting head 141 presses the rim 130, thereby fixing the coarse filtration unit 13.

The limiting spring 142 is sleeved on the limiting shaft 140, and the limiting spring 142 enables the limiting head 141 to have a trend of approaching the coarse filter unit 13. The mode of the limiting spring 142 is not limited, and for example, the limiting spring 142 is a compression spring, a tension spring, a torsion spring, or the like, and the setting position of the limiting spring 142 is different according to the mode of the limiting spring 142, which can be referred to the prior art. In the present embodiment, the limiting spring 142 employs a compression spring, and both ends of the limiting spring 142 are respectively abutted against the second end and the mounting plate 12. When the limiting shaft 140 is pulled upstream, the limiting head 141 can be far away from the frame 130, at this time, the limiting spring 142 is compressed under the pressure of the second end, and after the limiting head 141 is released, the limiting spring 142 can push the second end to reset, so that the limiting head 141 is pressed against the frame 130.

In other embodiments, the following scheme may also be employed: the limiting shaft 140 is only slidable in the axial direction relative to the mounting plate 12, but not rotatable about its own axis, in which case the limiting head 141 is rotatable about the limiting shaft 140, for example, the first section of the limiting shaft 140 is provided in a stepped shaft shape, the limiting head 141 is provided with a circular limiting hole, the limiting shaft 140 is inserted into the limiting hole, and the limiting head 141 is rotatable about the axis of the limiting shaft 140 with the limiting shaft 140 stationary. Note that, the movement between the limiting head 141 and the limiting shaft 140 in the axial direction is not limited, and for example, the limiting head 141 may be movable in the axial direction with respect to the limiting shaft 140 or may not be movable in the axial direction with respect to the limiting shaft 140.

In use, the elastic force of the limiting spring 142 may be too large or too small, if the elastic force of the limiting spring 142 is too large, it is difficult to pull the limiting head 141, and if the elastic force of the limiting spring 142 is too small, it is impossible to ensure that the limiting head 141 is pressed against the frame 130, so in this embodiment, the following improvement scheme is provided: the second end of the defining shaft 140 is provided with a threaded section 144 and a defining member 145, the defining member 145 being in threaded engagement with the threaded section 144, the position of the defining member 145 on the defining shaft 140 being changeable by screwing the defining member 145. In this embodiment, the threaded section 144 extends inwardly from one end of the limiting shaft 140 in a blind hole shape, the threaded section 144 is provided with an internal thread, and the limiting member 145 adopts a limiting bolt which is inserted into the threaded section 144 and is in threaded engagement with the internal thread. In other embodiments, the threaded section 144 may also be provided with external threads, and the limiter 145 may be a limiter nut that is threaded onto the threaded section 144.

Both ends of the limiting spring 142 are respectively abutted against the limiting member 145 and the mounting plate 12, and the pretightening force of the limiting spring 142 can be changed by adjusting the position of the limiting member 145. Taking the limiting spring 142 as a compression spring for example, the limiting assembly 14 is not subjected to an external force: when the limiting member 145 approaches the mounting plate 12, the initial pre-tightening force of the limiting spring 142 increases, so that the limiting head 141 can be pressed against the frame 130; when the limiter 145 is moved away from the mounting plate 12, the initial preload of the limiter spring 142 is reduced, enabling the limiter head 141 to be pulled more easily off of the bezel 130.

The shape of the defining head 141 is not limited, and in the present embodiment, the following may be adopted but is not limited: the defining heads 141 are arranged in a V-shape, and one defining head 141 may correspond to the corner of two adjacent coarse filtration units 13. The number of confining assemblies 14 can be reduced, reducing costs.

The two ends of the limiting head 141 are bent toward the coarse filtration unit 13, when the limiting assembly 14 is in the locking position, the bending portion 143 of the limiting head 141 can extend into the mounting opening 120 and abut against the coarse filtration unit 13, and the bending portion 143 can prevent the limiting head 141 from rotating abnormally, because after the limiting head 141 presses the frame 130, the bending portion 143 extends into the mounting opening 120 and is limited by the side wall of the mounting opening 120, and if the limiting head 141 rotates, the bending portion 143 abuts against the side wall of the mounting opening 120 and cannot rotate further.

In addition, in order to enhance the strength of the defining head 141, a reinforcing portion may be provided on the defining head 141, the reinforcing portion being bent toward one side of the defining head 141, and a bending direction of the reinforcing portion being opposite to that of the bending portion 143.

To facilitate user operation of the confinement assembly 14, the following may also be employed: the defining head 141 further includes a pull ring, the size of which is not limited, and preferably, a finger of a user can be inserted into the pull ring, and the pull ring is provided at one side of the defining head 141 so that the user can pinch the pull ring or hook the pull ring using the finger to pull the defining head 141 to move.

The installation method of the coarse filtration mechanism 10 provided in the present embodiment is as follows:

pulling the limiting head 141 to separate the bending part 143 of the limiting head 141 from the mounting opening 120, and at this time, the limiting spring 142 is gradually compressed;

the limiting head 141 is rotated so that the bending part 143 is no longer opposite to the mounting opening 120, and at this time, the bending part 143 is opposite to the mounting plate 12;

releasing the defining head 141, the defining spring 142 pushing the defining head 141 toward the mounting plate 12 until the bent portion 143 of the defining head 141 abuts the mounting plate 12;

the coarse filtration unit 13 is embedded in the mounting opening 120, at this time, the frame 130 butts against the step 121, and the periphery of the frame 130 is limited by the side wall of the mounting opening 120;

pulling the defining head 141 to disengage the bending portion 143 of the defining head 141 from the mounting plate 12, at which time the defining spring 142 is gradually compressed;

the limiting head 141 is rotated to make the bending part 143 opposite to the mounting opening 120;

the limiting head 141 is released, and the limiting spring 142 pushes the limiting head 141 to move toward the frame 130 until the bending portion 143 of the limiting head 141 abuts against the frame 130.

The steps may be increased, decreased, modified, and the order adjusted according to the structure of the coarse filtration mechanism 10.

The method for removing the coarse filtration mechanism 10 may refer to the above-mentioned partial steps, and will not be described herein.

The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims (10)

1. The utility model provides a coarse filtration mechanism of new trend system, its characterized in that includes housing, mounting panel, coarse filtration unit and limiting component, the mounting panel set up in the housing and have a plurality of installing port, every the installing port is all detachably inlayed and is equipped with coarse filtration unit, every at least two relative angles of coarse filtration unit are limited by limiting component, limiting component rotationally set up in the mounting panel and be used for pressing the angle of coarse filtration unit, limiting component rotates the in-process can lock or unblock coarse filtration unit.

2. The coarse filtration mechanism of the fresh air system of claim 1, wherein the limiting assembly includes a limiting shaft, a limiting head, and a limiting spring, the limiting shaft being axially slidably disposed on the mounting plate, the limiting shaft being disposed adjacent to an angle of the coarse filtration unit, the limiting head being fixed to the limiting shaft, the limiting head being rotatable relative to the limiting shaft or both being rotatable to enable the limiting head to approach or separate from the coarse filtration unit, the limiting spring being nested on the limiting shaft and the limiting head having a tendency to approach the coarse filtration unit.

3. The coarse filtration mechanism of claim 2 wherein the limiting shaft extends through the mounting plate, the limiting shaft includes a first end and a second end on opposite sides of the mounting plate, the limiting head is fixedly connected to the first end, and two ends of the limiting spring are respectively abutted to the second end and the mounting plate.

4. The coarse filtration mechanism of claim 3 wherein the second end of the limiting shaft is provided with a threaded section and a limiting member, the limiting member is in threaded engagement with the threaded section, two ends of the limiting spring are respectively abutted against the limiting member and the mounting plate, and the position of the limiting member on the limiting shaft is adjustable to change the pretightening force of the limiting spring.

5. The coarse filtration mechanism of claim 2 wherein the defining head is V-shaped and both ends of the defining head are bent toward the coarse filtration unit to extend into the mounting opening and against the coarse filtration unit.

6. The coarse filtration mechanism of the fresh air system of claim 2, wherein the defining head further comprises a pull ring disposed on one side of the defining head to enable a user to pull the defining head.

7. The coarse filtration mechanism of the fresh air system according to claim 1, wherein the housing includes a housing and an access door, one side of the housing being provided with an access opening, the access door being movably provided to the housing and for opening or closing the access opening.

8. The coarse filtration mechanism of any one of claims 1-7, wherein a step is provided on an inner side of each of the mounting openings, the coarse filtration unit including a rim embedded in the mounting opening and abutting the step.

9. The coarse filtration mechanism of claim 8, wherein the coarse filtration unit further comprises a strip of silicone, the strips of silicone are disposed around the rim, the strips of silicone extend from the rim, such that when the rim is inserted into the mounting opening, the strips of silicone deform and conform to the inner surface of the mounting opening.

10. The coarse filtration mechanism of claim 8 wherein the coarse filtration unit further comprises a filter element disposed on one side of the frame, the filter element comprising a plurality of filter bags vertically arranged in a flattened and side-by-side configuration with the openings of the filter bags facing outwardly.