Drying device for mineral aggregate detection

Abstract

The utility model discloses a drying device for mineral aggregate detection, which relates to the technical field of mineral detection and comprises a supporting component, a drying component and a driving component. A rotatable filter shell is arranged in the first cavity; a first air hole, a second air hole and a third air hole are sequentially formed in the side wall of the filter shell from top to bottom, the second air hole is located on the perpendicular bisector of the connecting line between the first air hole and the third air hole, the third air hole is located under the first air hole, and the second air hole is not located under the first air hole. The driving assembly is used for driving the filter shell to rotate; the drying assembly is used for blowing hot air flow into the filter shell; the second air hole is located on the perpendicular bisector of the connecting line between the first air hole and the third air hole, and in the rotating process of the filter shell, the midpoint of the connecting line between the first air hole and the third air hole and the second air hole alternately pass through the end of the exhaust pipe, so that staggered air inflow of the filter shell is achieved, the blowing and drying uniformity is improved, the drying area is increased, and the drying efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of mineral detection, in particular to a drying device for mineral material detection. Background Art

[0002] Ore is a mineral aggregate from which useful components can be extracted or which has certain properties that can be utilized. It can be divided into metal ore and non-metal ore. Ore is the original ore without any additives.

[0003] Mineral material testing items usually include element identification, phase analysis, particle size analysis, compression test, whiteness, moisture, radioactivity, density, gloss, etc. Before testing mineral materials, they usually need to be dried to remove surface moisture to avoid affecting the test results.

[0004] Traditional general-purpose dryers usually use fixed trays, the mineral materials to be tested are placed on the trays, and the hot air blower blows hot air to the trays and the mineral materials to be tested from fixed positions on one or both sides. The fixed-point hot air flow acts on the block mineral materials, which will cause the local temperature of the mineral materials to increase sharply, forming a temperature difference, and then destroying the internal structure of the mineral materials, such as cracks. Summary of the invention

[0005] In order to overcome the problem existing in the above background technology that "fixed-point drying causes a sudden increase in the local temperature of the mineral material, forms a temperature difference, and further destroys the internal structure of the mineral material", the utility model provides a drying device for mineral material detection.

[0006] The technical solution adopted by the utility model to solve the above technical problems is:

[0007] A drying device for mineral material detection, comprising a supporting assembly, a drying assembly and a driving assembly; the supporting assembly comprises a shell, the top surface of which is provided with a cover body that can be flipped open and closed; the shell is provided with a first cavity and a second cavity, the first cavity is provided with a rotatable filter shell; the drying assembly and the driving assembly are both installed in the second cavity, and the driving assembly is connected to the filter shell; the first cavity is provided with an inclined bottom surface; the filter shell is in the shape of a topless cylinder; the side wall of the filter shell is provided with a first air hole, a second air hole and a third air hole in sequence from top to bottom, and the bottom surface of the filter shell is provided with a fourth air hole; the second air hole is located on the mid-perpendicular line of the line connecting the first air hole and the third air hole, and the third air hole is located directly below the first air hole, and the second air hole is located not directly below the first air hole; the drying assembly comprises a hot air blower, and the hot air blower is provided with an exhaust pipe, and the exhaust pipe points to the second air hole.

[0008] As a further optimization solution of the utility model, a first bending portion is provided at the position of the first air hole, a second bending portion is provided at the position of the third air hole, and the adjacent first bending portion and the second bending portion are arranged in an eight-shaped shape.

[0009] As a further optimization solution of the utility model, a first protrusion and a second protrusion are respectively provided on the upper and lower sides of the second air hole, and the adjacent first protrusions and second protrusions are arranged in an eight-shaped shape.

[0010] As a further optimization solution of the present utility model, the first bending portion and the second bending portion are arranged on the upper and lower sides of the exhaust pipe; the first protrusion and the second protrusion are respectively arranged on the upper and lower sides of the exhaust pipe.

[0011] As a further optimization solution of the present invention, a first baffle is provided between adjacent first bending portions and first protrusions; and a second baffle is provided between adjacent second bending portions and second protrusions.

[0012] As a further optimization solution of the present invention, the first bent portion, the second bent portion, the first protrusion and the second protrusion are respectively connected to the side wall of the filter housing.

[0013] As a further optimization solution of the utility model, an annular transmission fin is provided on the top of the filter housing side wall, a thrust ball bearing is pressed on the lower surface of the transmission fin, and the thrust ball bearing is connected to the housing.

[0014] As a further optimization solution of the utility model, the outer edge of the transmission fin is provided with transmission teeth, and the driving assembly includes a driving motor and a driving gear connected to each other, and the driving gear is meshed with the transmission teeth.

[0015] As a further optimization solution of the present utility model, the drive motor is installed on the top of the inner wall of the second cavity.

[0016] As a further optimization scheme of the present utility model, a plurality of first air holes are provided and are arranged in a circular array along the side wall of the filter housing; a plurality of second air holes are provided and are arranged in a circular array along the side wall of the filter housing; a plurality of third air holes are provided and are arranged in a circular array along the side wall of the filter housing.

[0017] In summary, the utility model is beneficial in that: a drying device for mineral material detection includes a support component, a drying component and a driving component; a rotatable filter shell is provided in the first cavity; the side wall of the filter shell is provided with a first air hole, a second air hole and a third air hole in sequence from top to bottom, the second air hole is located on the midpoint of the line connecting the first air hole and the third air hole, and the third air hole is located directly below the first air hole, and the second air hole is located not directly below the first air hole. The utility model has a simple structure and reliable functions. The support component plays a structural support role, the driving component is used to drive the filter shell to rotate, and the drying component is used to blow hot air into the filter shell; the second air hole is located on the midpoint of the line connecting the first air hole and the third air hole. During the rotation of the filter shell, the midpoint of the line connecting the first air hole and the third air hole and the second air hole alternately pass through the end position of the exhaust pipe, so as to realize the staggered air intake of the filter shell, improve the uniformity of blowing and drying, increase the drying area, and improve the drying efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present application is further described below with reference to the accompanying drawings:

[0019] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0020] Figure 2 It is a schematic diagram of the supporting component structure;

[0021] Figure 3 Schematic diagram of filter housing structure;

[0022] Figure 4 This is a schematic diagram of the hot air blower installation location;

[0023] Figure 5 is a schematic diagram of the positional relationship among the first pore, the second pore and the third pore;

[0024] Figure 6 This is a schematic diagram of the state of the hot air blower blowing the second air hole;

[0025] Figure 7 A schematic diagram of the state of the hot air blower blowing the first air hole and the third air hole;

[0026] Figure 8 It is a schematic diagram of the position and structure of the first bending part and the second bending part;

[0027] Fig. 9 A schematic diagram of the position and structure of the first protrusion and the second protrusion;

[0028] Fig.10 A schematic diagram of the position and structure of the first baffle and the second baffle;

[0029] Fig.11 It is the installation position and structure diagram of the drive component;

[0030] Fig.12 for Fig.11 A partial enlarged schematic diagram in the middle.

[0031] Description of reference numerals:

[0032] In the figure,

[0033] 1. Support assembly; 11. Shell; 111. First cavity; 1111. Inclined bottom surface; 1112. Drain port; 112. Second cavity; 12. Cover; 13. Filter housing; 130. High pressure area; 131. First air hole; 1311. First bending portion; 132. Second air hole; 1321. First protrusion; 13211. First baffle; 1322. Second protrusion; 13221. Second baffle; 133. Third air hole; 1331. Second bending portion; 134. Fourth air hole; 135. Transmission fin; 14. Air outlet; 15. Thrust ball bearing; 136. Position limiting convex ring;

[0034] 2. Drying assembly; 21. Hot air blower; 211. Exhaust pipe; 212. Intake pipe;

[0035] 3. Driving assembly; 31. Driving motor; 32. Driving gear. DETAILED DESCRIPTION

[0036] Based on the above structural features of the present application, the implementation methods of the present application are further described:

[0037] Reference Figures 1 to 12 This embodiment provides a drying device for mineral material detection, comprising a support assembly 1, a drying assembly 2 and a driving assembly 3. The support assembly 1 is used to play a structural support role; the drying assembly 2 is used to blow hot air to the mineral material to be detected to achieve drying; the driving assembly 3 is used to realize the rotation of the mineral material to avoid drying dead corners.

[0038] Reference Figure 1 to Figure 3 The support assembly 1 includes a shell 11, and a cover 12 that can be flipped open and closed is provided on the top surface of the shell 11. One end of the cover 12 is connected to the shell 11 by a hinge, and the end of the cover 12 away from the hinge is detachably connected to the shell 11 by a spring buckle. The shell 11 is provided with a first cavity 111 and a second cavity 112, and the first cavity 111 and the second cavity 112 are respectively arranged on the left and right sides of the shell 11. A filter housing 13 that can rotate horizontally is provided in the first cavity 111; the drying assembly 2 and the driving assembly 3 are both installed in the second cavity 112, and the driving assembly 3 is connected to the filter housing 13.

[0039] Reference Figure 1-2The first cavity 111 is provided with an inclined bottom surface 1111; one end of the inclined bottom surface 1111 away from the second cavity 112 is inclined downward, and a drain port 1112 is provided at the lower end of the inclined bottom surface 1111. The drain port 1112 is opened on the side wall of the housing 11, and the drain port 1112 is connected to the lower end of the first cavity 111. Liquid water dripping from the filter housing 13 flows along the inclined bottom surface 1111 and is finally discharged through the drain port 1112, so as to avoid water accumulation in the first cavity 111.

[0040] Reference Figure 2 An air outlet 14 is provided on the side wall of the housing 11 away from the second cavity 112 , and the air outlet 14 is communicated with the first cavity 111 . The air outlet 14 is used to discharge the humid air in the first cavity 111 .

[0041] Reference Figure 3 to Figure 5 The filter housing 13 is in the shape of a cylinder with no top and a bottom; the side wall of the filter housing 13 is provided with a first air hole 131, a second air hole 132 and a third air hole 133 from top to bottom, and the bottom surface of the filter housing 13 is provided with a fourth air hole 134. The first air hole 131, the second air hole 132, the third air hole 133 and the fourth air hole 134 are all used to discharge the gaseous water in the measured mineral material in the filter housing 13, and the gaseous water is further discharged from the first cavity 111 through the air outlet 14; the liquid water in the measured mineral material drips from the filter housing 13 to the inclined bottom surface 1111 through the fourth air hole 134, and the liquid water is further discharged from the first cavity 111 through the drain port 1112.

[0042] Reference Figure 5 The second air hole 132 is located on the perpendicular midline of the line connecting the first air hole 131 and the third air hole 133 , and the third air hole 133 is located directly below the first air hole 131 , and the second air hole 132 is located not directly below the first air hole 131 .

[0043] Reference Figure 4 The drying component 2 includes a hot air blower 21, which is provided with an exhaust pipe 211 and an intake pipe 212. The intake pipe 212 penetrates the outer wall of the shell 11 of the second cavity 112 and is connected with the outside. The exhaust pipe 211 penetrates the shell 11 between the first cavity 111 and the second cavity 112 and is connected with the first cavity 111. The exhaust pipe 211 points to the second air hole 132, and the exhaust pipe 211 and the second air hole 132 are located at the same height.

[0044] Reference Figures 4 to 7During the rotation of the filter housing 13, the midpoint of the line between the first air hole 131 and the third air hole 133 and the second air hole 132 alternately pass through the end position of the exhaust pipe 211 to achieve staggered air intake of the filter housing 13. The staggered air intake includes: state ①, most of the hot air flows into the filter housing 13 through the first air hole 131 and the third air hole 133, and a small part of the hot air flows into the filter housing 13 through the second air hole 132; state ②, most of the hot air flows into the filter housing 13 through the second air hole 132, and a small part of the hot air flows into the filter housing 13 through the first air hole 131 and the third air hole 133. State ① and state ② are performed alternately to realize the change of air flow size in the first air hole 131, the second air hole 132 and the third air hole 133, improve the uniformity of blowing and drying, and avoid the single-point centralized blowing and drying in traditional technology; since the heights of the first air hole 131, the second air hole 132 and the third air hole 133 are different, it is possible to dry the measured mineral materials at different heights, thereby increasing the drying area and improving the drying efficiency.

[0045] Reference Figure 7 and Figure 8 A first bending portion 1311 is provided at the position of the first air hole 131, and a second bending portion 1331 is provided at the position of the third air hole 133. The adjacent first bending portions 1311 and second bending portions 1331 are arranged in an eight-shaped shape. The first bending portion 1311 and the second bending portion are used to guide the hot air flow.

[0046] Reference Figure 6 and Fig. 9 The second air hole 132 is provided with a first protrusion 1321 and a second protrusion 1322 at the upper and lower sides, respectively, and the adjacent first protrusions 1321 and second protrusions 1322 are arranged in an eight-shaped shape. The first protrusion 1321 and the second protrusion 1322 are used to guide the hot air flow.

[0047] Reference Figure 6 to Figure 9 The first bending portion 1311 and the second bending portion 1331 are respectively disposed on the upper and lower sides of the exhaust pipe 211 ; the first protrusion 1321 and the second protrusion 1322 are respectively disposed on the upper and lower sides of the exhaust pipe 211 .

[0048] Reference Figure 6 to Figure 9 The first bending portion 1311, the second bending portion 1331, the first protrusion 1321 and the second protrusion 1322 are respectively fixedly connected to the side wall of the filter housing 13. The first bending portion 1311, the second bending portion 1331 and the filter housing 13 are formed by integral punching and bending; the first protrusion 1321, the second protrusion 1322 and the filter housing 13 are formed by integral deep drawing. The upper end of the first bending portion 1311 is connected to the top edge of the first air hole 131, and the lower end of the second bending portion 1331 is connected to the bottom edge of the third air hole 133. The first bending portion 1311 and the second bending portion 1331 are both convex.

[0049] Reference Figure 6 and Figure 7 The first bending portion 1311 is used to increase the resistance of the hot air flow to the upward flow, and the second bending portion 1331 is used to increase the resistance of the hot air flow to the downward flow, so that as much hot air as possible can flow into the first air hole 131 and the third air hole 133; the first protrusion 1321 is used to increase the resistance of the hot air flow to the upward flow, and the second protrusion 1322 is used to increase the resistance of the hot air flow to the downward flow, so that as much hot air as possible can flow into the second air hole 132.

[0050] Reference Fig.10 A first baffle 13211 is provided between the adjacent first bend 1311 and the first protrusion 1321, and the two ends of the first baffle 1321 are respectively sealed and fixedly connected (for example, welded) with the first bend 1311 and the first protrusion 1321; a second baffle 13221 is provided between the adjacent second bend 1331 and the second protrusion 1322, and the two ends of the second baffle 13221 are respectively sealed and fixedly connected (for example, welded) with the second bend 1331 and the second protrusion 1322. The first baffle 13211 is sealed and fixedly connected (for example, welded) with the filter housing 13, and the second baffle 13221 is sealed and fixedly connected (for example, welded) with the filter housing 13. Figure 6 , Figure 7 and Fig.10 When the hot air blower 21 blows hot air toward the filter housing 13, the air pressure outside the first air hole 131, the second air hole 132 and the third air hole 133 gradually increases under the obstruction of the first bending portion 1311, the second bending portion 1331, the first protrusion 1321, the second protrusion 1322, the first baffle 13211 and the second baffle 13221, thereby forming a high-pressure area 130, so as to facilitate the hot air flow to flow into the inner cavity of the filter housing 13 through the first air hole 131, the second air hole 132 and the third air hole 133, reduce the loss of hot air through the gap between the outer wall of the filter housing 13 and the inner wall of the first cavity 111, and improve the utilization rate of hot air.

[0051] Reference Fig.11 and Fig.12 , an annular transmission fin 135 is provided on the top of the side wall of the filter housing 13 (for example, through an integrated fixed connection), and a thrust ball bearing 15 is pressed on the lower surface of the transmission fin 135, and the thrust ball bearing 15 is connected to the housing 11. The thrust ball bearing 15 includes an upper ring body and a lower ring body connected by balls, and the lower ring body is fixedly mounted on the upper surface of the housing 11 around the top of the first cavity 111 by bolts, and the transmission fin 135 is naturally pressed on the upper ring body. A rotating shaft is installed at the center of the bottom surface of the filter housing 13 by bolts, and a sleeve adapted to the rotating shaft is installed on the bottom surface of the first cavity 111 by bolts.

[0052] Reference Fig.12The outer edge of the transmission fin 135 is provided with a transmission tooth, and the driving assembly 3 includes a driving motor 31 and a driving gear 32 connected to each other, and the driving gear 32 is meshed with the transmission tooth. The driving motor 31 can drive the filter housing 13 to rotate through the driving gear 32, and the hot air flow is blown on the surface of the measured mineral material rotating with the filter housing 13, so as to increase the drying area of ​​the measured mineral material and improve the drying efficiency and effect.

[0053] Reference Fig.12 The drive motor 31 is installed on the top of the inner wall of the second cavity 112, the housing of the drive motor 31 is fixedly connected to the inner wall of the second cavity 112 by bolts, the drive motor 31 is arranged longitudinally, and the output shaft of the drive motor 31 is fixedly connected to the drive gear 32 by bolts or keys. The drive gear 32 is a bevel gear, and the transmission teeth of the transmission fin 135 are pressed on the oblique upper side of the bevel gear to facilitate the removal and installation of the filter housing 13.

[0054] Reference Fig.12 The outer wall of the filter housing 13 is fixed with a limiting convex ring 136 by bolts, and the limiting convex ring 136 is located at the lower surface of the transmission fin 135. The outer diameter of the limiting convex ring 136 is 1-5 mm smaller than the inner diameter of the thrust ball bearing 15, so as to reduce the shaking amplitude of the filter housing 13 during the rotation process, improve the rotation stability, and thus reduce the collision damage of the filter housing 13 caused by shaking.

[0055] During removal, the user lifts the filter housing 13 upwards and can pull the filter housing 13 out of the first cavity 111 .

[0056] During installation, the user places the filter housing 13 downwardly in the first cavity 111 , inserts the shaft into the shaft sleeve, presses the transmission fins 135 onto the upper surface of the upper ring body, and meshes the transmission teeth with the driving gear 32 .

[0057] A plurality of first air holes 131 are provided and arranged in a circular array along the side wall of the filter housing 13 ; a plurality of second air holes 132 are provided and arranged in a circular array along the side wall of the filter housing 13 ; a plurality of third air holes 133 are provided and arranged in a circular array along the side wall of the filter housing 13 .

[0058] Usage steps: ① Install the filter housing 13 in the first cavity 111; ② Place the mineral material to be tested in the filter housing 13 and snap on the cover 12; ③ Start the drive motor 31 and the hot air blower 21. The drive motor 31 drives the filter housing 13 and the mineral material to be tested to rotate at the same speed and in the same direction. The hot air blower 21 blows hot air into the filter housing 13 to achieve drying; ④ Turn off the hot air blower 21 and the drive motor 31, and open the cover 12 to dissipate heat; ⑤ Take out the filter housing 13, and further take out the mineral material to be tested.

[0059] The utility model further includes an electrical cabinet, which is fixedly mounted on the inner wall of the second cavity 112 by bolts; the drive motor 31 and the hot air blower 21 are respectively connected to the electrical cabinet by wires and signal lines; the electrical cabinet is respectively connected to the external power supply and the external computer by wires and signal lines, and the computer controls the start and stop of the drive motor 31 and the hot air blower 21 in the utility model through the electrical cabinet. The hot air blower 21 is a blower with a built-in electric heating wire, which is a conventional existing technology in the industry, and the specific structure is not repeated.

[0060] The filter housing 13 and the casing 11 are made of stainless steel to avoid rust.

[0061] The utility model has a simple structure and reliable functions. The support component 1 plays a structural supporting role, the driving component 3 is used to drive the filter housing 13 to rotate, and the drying component 2 is used to blow hot air into the filter housing 13; the second air hole 132 is located on the midpoint of the line between the first air hole 131 and the third air hole 133. During the rotation of the filter housing 13, the midpoint of the line between the first air hole 131 and the third air hole 133 and the second air hole 132 alternately pass through the end position of the exhaust pipe 211, thereby realizing staggered air intake of the filter housing 13, improving the uniformity of blowing and drying, increasing the drying area, and improving the drying efficiency.

[0062] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "up", "down", "left" and "right" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0063] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, or a connection through an intermediate medium, or the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] To sum up, for those skilled in the art, according to the guidance of the present invention, without departing from the principle and spirit of the present invention, the changes, modifications, replacements and deformations made to the present invention still fall within the protection scope of the present invention.

Claims

1. A drying device for mineral material detection, characterized in that: It comprises a supporting component (1), a drying component (2) and a driving component (3); The support assembly (1) comprises a shell (11), the top surface of the shell (11) being provided with a cover (12) capable of being flipped open and closed; the shell (11) being provided with a first cavity (111) and a second cavity (112), a rotatable filter housing (13) being provided in the first cavity (111); the drying assembly (2) and the driving assembly (3) are both installed in the second cavity (112), and the driving assembly (3) is connected to the filter housing (13); The first cavity (111) is provided with an inclined bottom surface (1111); The filter housing (13) is in the shape of a cylinder without a top; the side wall of the filter housing (13) is provided with a first air hole (131), a second air hole (132) and a third air hole (133) in order from top to bottom, and the bottom surface of the filter housing (13) is provided with a fourth air hole (134); the second air hole (132) is located on the perpendicular midline of the line connecting the first air hole (131) and the third air hole (133), and the third air hole (133) is located directly below the first air hole (131), and the second air hole (132) is located not directly below the first air hole (131); The drying component (2) comprises a hot air blower (21), wherein the hot air blower (21) is provided with an exhaust pipe (211), and the exhaust pipe (211) points to the second air hole (132).

2. The drying device for mineral material detection according to claim 1, characterized in that: A first bending portion (1311) is provided at the position of the first air hole (131), a second bending portion (1331) is provided at the position of the third air hole (133), and the adjacent first bending portions (1311) and second bending portions (1331) are arranged in an eight-shaped shape.

3. The drying device for mineral material detection according to claim 2, characterized in that: A first protrusion (1321) and a second protrusion (1322) are respectively provided on the upper and lower sides of the second air hole (132), and adjacent first protrusions (1321) and second protrusions (1322) are arranged in an eight-shaped shape.

4. The drying device for mineral material detection according to claim 3, characterized in that: The first bending portion (1311) and the second bending portion (1331) are respectively arranged on the upper and lower sides of the exhaust pipe (211); and the first protrusion (1321) and the second protrusion (1322) are respectively arranged on the upper and lower sides of the exhaust pipe (211).

5. The drying device for mineral material detection according to claim 4, characterized in that: A first baffle (13211) is provided between adjacent first bending portions (1311) and first protrusions (1321); and a second baffle (13221) is provided between adjacent second bending portions (1331) and second protrusions (1322).

6. The drying device for mineral material detection according to claim 5, characterized in that: The first bent portion (1311), the second bent portion (1331), the first protrusion (1321), and the second protrusion (1322) are respectively connected to the side wall of the filter housing (13).

7. The drying device for mineral material detection according to claim 6, characterized in that: An annular transmission fin (135) is provided on the top of the side wall of the filter housing (13), a thrust ball bearing (15) is pressed onto the lower surface of the transmission fin (135), and the thrust ball bearing (15) is connected to the housing (11).

8. The drying device for mineral material detection according to claim 7, characterized in that: The outer edge of the transmission fin (135) is provided with transmission teeth, and the driving assembly (3) comprises a driving motor (31) and a driving gear (32) which are connected to each other, and the driving gear (32) is meshed with the transmission teeth.

9. The drying device for mineral material detection according to claim 8, characterized in that: The driving motor (31) is mounted on the top of the inner wall of the second cavity (112).

10. The drying device for mineral material detection according to any one of claims 1 to 9, characterized in that: A plurality of the first air holes (131) are provided and are arranged in a circular array along the side wall of the filter housing (13); a plurality of the second air holes (132) are provided and are arranged in a circular array along the side wall of the filter housing (13); and a plurality of the third air holes (133) are provided and are arranged in a circular array along the side wall of the filter housing (13).

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