filter unit

Abstract

This product provides a filter unit that facilitates maintenance work such as dust removal and suppresses dust dispersion. [Solution] The filter unit has a bottomed casing 50 that extends cylindrically along a central axis 90, a filter that extends cylindrically in the axial direction within the internal space of the casing, a lid that covers the opening of the casing 50, and a protective plate 80. The inlet 510 opens on the inner circumferential surface of the casing 50, allowing gas containing dust to flow into the space outside the filter. The outlet opens on the bottom surface of the casing 50, allowing the gas that has passed through the filter to flow out to the outside. The protective plate holder 55 is located on the side of the inlet 510 inside the casing 50 and extends in the axial direction. The protective plate 80 is movable in the axial direction between the inner circumferential surface of the casing 50 and the protective plate holder 55. When the protective plate 80 faces the inlet 510 in the radial direction, the protective plate 80 covers the space radially inside the inlet and has a gap between it and the inlet 510 in the radial direction.

Description

Technical Field

[0001] The present invention relates to a filter unit that filters dust in gas with a filter.

Background Art

[0002] Conventionally, there has been known an apparatus that processes a material composed of powder or granules (hereinafter referred to as "powder and granular material") using an air flow. For example, apparatuses for drying powder and granular material by a heated air flow, apparatuses for conveying powder and granular material by an air flow, and the like are known. This type of apparatus is provided with a filter unit for removing fine dust including powder and granular material mixed in the air flow.

[0003] When a filter unit is in use, if dust or high-temperature gas directly collides with the filter, or if dust or gas unevenly collides with a specific part of the filter for a long period of time, this may lead to damage or clogging of the filter. Accordingly, Patent Document 1 discloses a structure that can prevent dust or gas from directly colliding with the side surface of the filter or unevenly colliding with a specific part of the filter.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] In the dust collector of Patent Document 1, a filter (12) is vertically provided on the bottom surface of a cover plate (9) that partitions the inside and outside of a machine body (1). An upper end opening (12a) of the filter (12) opens on the upper surface of the cover plate (9). A protection cylinder (10) is also vertically provided on the bottom surface of the cover plate (9) toward the outside of the filter (12). A passage gap (11) for causing dust-containing air sucked from an attachment port (4) to swirl along the periphery of the protection cylinder (10) is formed between the peripheral surface of the protection cylinder (10) and the inner wall surface of the machine body (1).

[0006] In the dust collector of Patent Document 1, a protective cylinder (10) is provided on the outside of the filter (12), which prevents dust-laden air sucked in from the mounting port (4) from directly colliding with the filter (12) or colliding unevenly with specific parts of the filter (12). On the other hand, with repeated use of the dust collector, dust adheres to and accumulates on the circumferential surface of the protective cylinder (10) and the inner wall surface of the machine body (1). For this reason, it is necessary to remove the cover plate (9) at regular intervals to remove this dust. In addition, it may be necessary to remove and clean or replace components such as the filter (12). However, since the protective cylinder (10) is fixed to the bottom surface of the cover plate (9) together with the filter (12), there is a risk of dust scattering when the cover plate (9) is removed to remove the dust.

[0007] This invention has been made in view of these circumstances, and aims to provide a filter unit that allows for easy removal and cleaning of dust, maintenance work such as replacement of components, and suppression of dust dispersion. [Means for solving the problem]

[0008] To solve the above problems, the first invention of the present application provides a filter unit capable of filtering dust in a gas with a filter and discharging the gas that has passed through the filter, comprising a bottomed casing, the filter, a lid, and a protective plate. The casing extends cylindrically around a central axis along the central axis. The filter is housed in the internal space of the casing, has a plurality of filter holes with a diameter smaller than the dust, and extends cylindrically parallel to the central axis. The lid covers the opening of the casing. The protective plate is arranged in the internal space of the casing along a part of the inner circumferential surface of the casing. The internal space of the casing is partitioned by the filter into an outer space of the filter and an inner space of the filter. The casing also has a filter holding portion, an inlet, an outlet, and a protective plate holding portion. The filter holding portion holds the filter in the internal space of the casing parallel to the central axis. The inlet opens to the inner surface of the casing and allows the gas containing the dust to flow into the outer space of the filter. The outlet opens to the bottom or inner surface of the casing and allows the gas that has passed through the filter to flow out from the inner space of the filter. The protective plate holder is located on the side of the inlet when the casing is viewed in the axial direction and extends in the axial direction. The protective plate is movable in the axial direction between the inner surface of the casing and the protective plate holder. When the protective plate faces the inlet in the radial direction, the protective plate covers the space radially inside the inlet and has a gap between it and the inlet in the radial direction.

[0009] The second invention of this application is a filter unit of the first invention, wherein the protective plate is flat.

[0010] The third invention of this application is a filter unit according to the first or second invention, further comprising a ventilation hole on the side of the inlet that communicates the inlet with a space radially inward of the protective plate when the protective plate faces the inlet radially.

[0011] The fourth invention of this application is a filter unit of the third invention, wherein when the protective plate faces the inlet in the radial direction, the total area of ​​the communication points that connect the space radially inside the protective plate with the space radially outside the protective plate is greater than the opening area of ​​the inlet.

[0012] The fifth invention of this application is a filter unit of the first invention, wherein the protective plate has a labyrinth structure in which a plurality of members are arranged while overlapping each other in the radial direction.

[0013] The sixth invention of this application is a filter unit of the first invention, wherein the protective plate has a tray shape in which its end is inclined toward the central axis.

[0014] The seventh invention of this application is a filter unit of the first invention, wherein the protective plate has a curved plate shape that conforms to the inner circumferential surface of the casing.

[0015] The eighth invention of this application is a filter unit according to any one of the first to seventh inventions, wherein the dust includes resin pellets which are raw materials for resin molded products. [Effects of the Invention]

[0016] According to the first to eighth inventions of this application, the inlet can be exposed by removing the lid as a separate unit and sliding a protective plate, which is separate from the lid, in the axial direction. This makes it easy to remove dust adhering to or accumulated near the inlet, and to perform maintenance work such as cleaning the inside of the casing and replacing components. Furthermore, it is possible to suppress the scattering of dust when performing these operations.

[0017] In particular, according to the second invention of this application, protective plates can be easily manufactured.

[0018] In particular, according to the third and fourth inventions of this application, the gas that flows into the internal space of the casing through the inlet can be flowed more smoothly radially inward from the protective plate.

[0019] In particular, according to the fifth invention of the present application, the flow of gas that has flowed into the inner space of the casing through the inlet can be dispersed, and the flow velocity of the gas can be further reduced before the gas reaches the filter. This makes it possible to further reduce the load applied to the filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [Figure 1] It is a diagram conceptually showing the configuration of a drying device. [Figure 2] It is a block diagram showing the connection between a control unit and each part. [Figure 3] It is a side view of a filter unit. [Figure 4] It is a front view of a filter unit. [Figure 5] It is an exploded perspective view of a filter unit. [Figure 6] It is a longitudinal sectional view of a filter unit. [Figure 7] It is a partial perspective view of a protection plate holding portion and a protection plate. [Figure 8] It is a partial longitudinal sectional view of a filter unit. [Figure 9] It is a longitudinal sectional view of a filter unit according to a first modified example. [Figure 10] It is a longitudinal sectional view of a filter unit according to a second modified example. [Figure 11] It is a longitudinal sectional view of a filter unit according to a third modified example. MODES FOR CARRYING OUT THE INVENTION

[0021] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. The constituent elements described in this embodiment are merely illustrative, and are not intended to limit the scope of the present invention only thereto. In addition, in the drawings, for easy understanding, the dimensions and numbers of respective parts may be exaggerated or simplified as necessary. Further, in order to prevent the drawings from becoming complicated, hatching may be omitted in some cases.

[0022] <1. Overall configuration of the drying equipment> Figure 1 is a conceptual diagram showing the configuration of a drying apparatus 1 having a filter unit 32 according to one embodiment of the present invention. This drying apparatus 1 is used, for example, in the molding process of plastic products to dry resin pellets 9, which are granular materials. In other words, the resin pellets 9 are used as raw materials for resin molded products such as plastics.

[0023] As shown in Figure 1, the drying apparatus 1 comprises a storage tank 10, a material supply mechanism 20, an airflow circulation mechanism 30, and a control unit 40. The drying apparatus 1 supplies resin pellets 9, which are the raw material, from the material supply mechanism 20 to the storage tank 10, dries the resin pellets 9 inside the storage tank 10, and then discharges the dried resin pellets 9 to the subsequent injection molding machine 2. However, the subsequent device is not limited to an injection molding machine, and may be other devices such as an extrusion molding machine, a blow molding machine, or a compression molding machine.

[0024] The storage tank 10 is a container for storing and drying resin pellets 9 in its internal space. As shown in Figure 1, the storage tank 10 has a substantially cylindrical side wall portion 11, a funnel-shaped bottom portion 12 that gradually narrows downward from the lower end of the side wall portion 11, and a top plate portion 13 that covers the upper part of the storage tank 10. Inside the storage tank 10, there is a space for storing and heating / drying the resin pellets 9. The shape of the storage tank 10 may be other shapes. For example, the shape of the side wall portion 11 may be a rectangular cylinder.

[0025] A supply hopper 21, described later, is installed above the top plate 13. The supply hopper 21 is connected to the storage tank 10 via an inlet 14 provided on the top plate 13 of the storage tank 10. The inlet 14 can be opened and closed manually or automatically by an operator. The downstream end of a supply pipe 22, described later, is also connected to the supply hopper 21. When supplying resin pellets 9 to the storage tank 10, the resin pellets 9 are supplied from the supply pipe 22 to the inside of the storage tank 10 via the supply hopper 21.

[0026] Furthermore, below the bottom 12, there is a discharge pipe (not shown) for discharging the dried resin pellets 9 from the storage tank 10 to the injection molding machine 2 below. The discharge pipe is connected to the storage tank 10 via an outlet 15 provided in the bottom 12. The discharge pipe is also equipped with a valve that switches the outlet 15 between an open state and a closed state. When the valve is opened, the resin pellets 9 in the storage tank 10 are discharged to the injection molding machine 2 through the outlet 15. On the other hand, when the valve is closed, the discharge of resin pellets 9 from the storage tank 10 is stopped.

[0027] The material supply mechanism 20 is a mechanism for supplying resin pellets 9 before drying into the storage tank 10. The material supply mechanism 20 in this embodiment includes a supply hopper 21, a supply pipe 22, a supply tank 23, and a transport blower 24.

[0028] The supply hopper 21 is a container that temporarily holds the resin pellets 9 before they are supplied to the storage tank 10. As described above, the supply hopper 21 is connected to the storage tank 10 via an inlet 14 provided on the top plate 13 of the storage tank 10. The downstream end of the supply pipe 22 is connected to the side of the supply hopper 21. The upstream end of the supply pipe 22 is connected to the supply tank 23. The supply tank 23 contains the undried resin pellets 9 that will be used as raw material.

[0029] For example, a known blower having multiple blades is used for the transport blower 24. The transport blower 24 is connected to the supply hopper 21 via piping 25. A perforated metal plate 211 is provided at the connection between the supply hopper 21 and the piping 25. The perforated metal plate 211 has multiple through holes that restrict the passage of resin pellets 9 while allowing the passage of gas.

[0030] When the transport blower 24 is driven, the rotation of multiple blades generates an airflow that draws gas in from the piping 25 and discharges it to the outside. As a result, the resin pellets 9 in the supply tank 23, which is the raw material source, are transported by air to the supply hopper 21 via the supply pipe 22 (see arrow D1 in Figure 1). At this time, the movement of the resin pellets 9 from the supply hopper 21 to the piping 25 is blocked by the perforated metal plate 211. Therefore, the resin pellets 9 are stored in the supply hopper 21 without flowing into the piping 25.

[0031] After the resin pellets 9 are stored in the supply hopper 21, when the inlet 14 is opened and the airflow is stopped, gravity causes the resin pellets 9 in the supply hopper 21 to fall through the inlet 14 into the storage tank 10. In this way, the material supply mechanism 20 intermittently supplies (batch supply) resin pellets 9 into the storage tank 10 by repeatedly generating and stopping the airflow.

[0032] However, the method of supplying the resin pellets 9 to the storage tank 10 does not necessarily have to be batch supply as described above. For example, the resin pellets 9 may be continuously supplied into the storage tank 10 by suction using negative pressure. Alternatively, an operator may directly put the resin pellets 9 into the storage tank 10.

[0033] The airflow circulation mechanism 30 is a mechanism that circulates gas in order to supply hot air for drying into the storage tank 10. In this embodiment, the airflow circulation mechanism 30 circulates the gas by supplying dry, high-temperature gas into the storage tank 10 and then heating and drying the gas discharged from the storage tank 10 again before supplying it back to the storage tank 10. As shown in Figure 1, the airflow circulation mechanism 30 includes an airflow circulation path 31, a filter unit 32, a cooler 33, a drying blower 34, a moisture adsorption unit 35, and a heating unit 36.

[0034] The airflow circulation path 31 is a pipe that forms a circulation path for circulating gas. The upstream end of the airflow circulation path 31 is connected to a suction port 16 provided on the upper part of the side wall 11 of the storage tank 10. The suction port 16 communicates with the internal space of the storage tank 10. The downstream end of the airflow circulation path 31 penetrates the side wall 11 of the storage tank 10 and opens in the internal space of the storage tank 10, forming an outlet 17. Along the path of the airflow circulation path 31, from upstream to downstream, a filter unit 32, a cooler 33, a drying blower 34, a moisture adsorption unit 35, and a heating unit 36 ​​are provided.

[0035] For example, a known blower having multiple blades is used as the drying blower 34. When the drying blower 34 is driven, the rotation of the multiple blades generates an airflow in the airflow circulation path 31 from the suction port 16 to the outlet port 17 (see arrow D2 in Figure 1). As a result, the gas in the storage tank 10 is drawn into the airflow circulation path 31 from the suction port 16.

[0036] At that time, fine dust (including resin pellets 9) in the gas drawn from the storage tank 10 into the airflow circulation path 31 is collected by the filter unit 32. This prevents dust from being drawn into equipment located downstream of the filter unit 32 and causing malfunctions. The more detailed structure of the filter unit 32 will be described later.

[0037] The cooler 33 cools the gas drawn from the storage tank 10 into the airflow circulation path 31 by known methods such as heat exchange. As a result, the gas that has passed through the cooler 33 is in a state where moisture can be easily removed.

[0038] The moisture adsorption unit 35 is a device that adsorbs (dehumidifies) moisture contained in the gas after it has been cooled in the cooler 33. Various known devices, such as those using a honeycomb-shaped ceramic body, can be used for the moisture adsorption unit 35. When using a honeycomb-shaped ceramic body, the ceramic body should contain zeolite, which has the property of adsorbing moisture.

[0039] The heating unit 36 ​​heats the gas that has been dehumidified in the moisture adsorption unit 35 using a known device such as an electric heater. In other words, the heating unit 36 ​​heats the gas flowing through the airflow circulation path 31. As a result, the gas that passes through the heating unit 36 ​​becomes hot air. The gas, which has become dry hot air after passing through the moisture adsorption unit 35 and the heating unit 36, is then blown out from the outlet 17 into the internal space of the storage tank 10.

[0040] The dry, hot air blown out from the outlet 17 diffuses into the storage tank 10 through the gaps between the resin pellets 9 stored inside the tank. As a result, the moisture contained in the resin pellets 9 is transferred to the dry, hot air. Consequently, the resin pellets 9 dry out.

[0041] The gas from which moisture has been absorbed from the resin pellets 9 is drawn back into the airflow circulation path 31 via the suction port 16, and then dust particles in the gas are collected in the filter unit 32. After passing through the filter unit 32, the gas is cooled again in the cooler 33, dehumidified in the moisture adsorption unit 35, and then heated in the heating unit 36 ​​before being sent into the storage tank 10. Through this gas circulation, the drying process of the resin pellets 9 proceeds in the storage tank 10. However, the gas from which moisture has been absorbed from the resin pellets 9 may not be circulated after being drawn into the airflow circulation path 31 via the suction port 16, but instead passed through the filter unit 32 and was discharged to the outside. In other words, the airflow circulation path 31 may be used as an exhaust pipe instead of a circulation path. In this case, the cooler 33 and moisture adsorption unit 35 can be omitted.

[0042] The control unit 40 is a unit for controlling the operation of each part within the drying apparatus 1. Figure 2 is a block diagram showing the connections between the control unit 40 and each part within the drying apparatus 1. As shown in Figure 2, the control unit 40 is electrically connected to the transport blower 24, cooler 33, drying blower 34, moisture adsorption unit 35, and heating unit 36, respectively. The control unit 40 may be composed of a computer having a processing unit such as a CPU and memory, or it may be composed of an electrical circuit. The control unit 40 controls the operation of each of the above parts based on a preset program or an external input signal. This allows the drying process of the resin pellets 9 in the drying apparatus 1 to proceed. However, the transport blower 24 and the drying blower 34 may be disconnected from the control unit 40 and operated manually by an operator.

[0043] <2. Detailed structure of the filter unit> Next, the more detailed structure of the filter unit 32 will be described. In the following, the direction parallel to the central axis 90 of the casing 50, which will be described later, will be referred to as the "axial direction," the direction perpendicular to the central axis 90 will be referred to as the "radial direction," and the direction along the arc centered on the central axis 90 will be referred to as the "circumferential direction." Furthermore, in this application, "parallel direction" includes substantially parallel directions, and "perpendicular direction" also includes substantially orthogonal directions.

[0044] Furthermore, within the "axial direction," the side opposite to the bottom plate portion 52 of the casing 50, which will be described later, is referred to as the "one axial side," and the side with the bottom plate portion 52 is referred to as the "other axial side." Also, within the "radial direction," the side of the casing 50 that approaches the central axis 90 is referred to as the "radial inner side," and the side that moves away from the central axis 90 is referred to as the "radial outer side."

[0045] As described above, the filter unit 32 is a device for collecting dust in the gas drawn in from the storage tank 10 via the airflow circulation path 31. The dust includes resin pellets 9 (powder and granules) mixed in with the gas flowing from the storage tank 10 via the airflow circulation path 31, and may also contain dust and other particles.

[0046] Figure 3 is a side view of the filter unit 32. Figure 4 is a front view of the filter unit 32 viewed from one side in the axial direction. Figure 5 is an exploded perspective view of the filter unit 32. Figure 6 is a longitudinal cross-sectional view of the filter unit 32 viewed from position BB in Figure 4. Note that in Figures 5 and 6, the multiple filter holes of the filter 70, which will be described later, are not shown. As shown in Figures 3 to 6, the filter unit 32 has a bottomed casing 50, a lid 60, a cylindrical filter 70 housed in the internal space of the casing 50, and a protective plate 80 arranged in the internal space of the casing 50.

[0047] The filter 70 is housed inside the casing 50. In this embodiment, the filter 70 is, for example, a dust collection filter made of a resin such as polyethylene terephthalate (PET) or cloth. However, the filter 70 may be a high-performance filter such as a HEPA filter or ULPA filter, or a cartridge filter. In this embodiment, the shape of the filter 70 is cylindrical. As will be described in detail later, the filter 70 is arranged in the internal space of the casing 50 such that the central axis of the filter 70 and the central axis 90 of the casing 50 are parallel. That is, the filter 70 extends in a cylindrical shape parallel to the central axis 90.

[0048] The filter 70 has a repeating ridged shape (pleats) in the circumferential direction, which is not shown in the illustration. The filter 70 is formed, for example, by curving a bellows-shaped dust collection sheet into a cylindrical shape. In addition, a plurality of filter holes, not shown in the illustration, are formed on the surface of the filter 70. Each of the plurality of filter holes penetrates the filter 70 in the thickness direction. The diameter of each filter hole is smaller than the diameter of the dust (e.g., resin pellets 9).

[0049] The casing 50 is a hollow metal frame. The casing 50 is formed, for example, by applying a blackening treatment to the surface of a frame made of steel material for rust prevention. The casing 50 has a side portion 51 and a bottom plate portion 52. The side portion 51 extends cylindrically around the central axis 90 along the central axis 90. The bottom plate portion 52 is a plate-shaped member that covers the other axial end of the side portion 51. That is, the casing 50 has a bottomed shape that extends cylindrically around the central axis 90 along the central axis 90. As shown in Figure 6, below, the radially inner end face of the side portion 51 will be referred to as the "inner circumferential surface 511 of the casing 50", and the axial end face of the bottom plate portion 52 will be referred to as the "bottom surface 521 of the casing 50".

[0050] An inlet 510 is provided on the inner circumferential surface 511 of the casing 50. In this embodiment, the inlet 510 opens at the lower part of the inner circumferential surface 511 of the casing 50. The inlet 510 connects the internal space of the casing 50 to the external space. One end of the upstream connecting pipe 91, which is a circular pipe, is connected to the inlet 510. The other end of the upstream connecting pipe 91 is connected to the airflow circulation path 31, which is located upstream of the filter unit 32 in the gas circulation path. As a result, the gas flowing through the airflow circulation path 31 flows into the internal space of the casing 50 through the inlet 510.

[0051] An outlet 520 is provided on the bottom surface 521 of the casing 50. In this embodiment, the outlet 520 opens near the center of the bottom surface 521 of the casing 50. The outlet 520 connects the internal space of the casing 50 with the external space. One end of a downstream connecting pipe 92, which is an L-shaped bent circular pipe, is connected to the outlet 520. The other end of the downstream connecting pipe 92 is connected to an airflow circulation path 31 located downstream of the filter unit 32 in the gas circulation path. As a result, the gas that has passed through the internal space of the casing 50 flows out into the airflow circulation path 31 via the outlet 520.

[0052] Furthermore, the internal space of the casing 50 is provided with a filter holding section 53, a lid holding section 54, and a protective plate holding section 55.

[0053] The filter holding portion 53 is a member that holds the filter 70 in the internal space of the casing 50. As shown in Figures 5 and 6, the filter holding portion 53 in this embodiment extends in a flat plate shape in the longitudinal direction, and its longitudinal direction is parallel to the axial direction. The other end of the filter holding portion 53 in the axial direction is fixed to the bottom surface 521 of the casing 50, for example, by adhesive or welding. The filter holding portion 53 is also fixed to the bottom surface 521 while traversing the outlet 520. Furthermore, the radial outer surface 531 of the filter holding portion 53 is parallel to the central axis 90. The inner circumferential surface of the cylindrical filter 70 is supported by the radial outer surface 531 of the filter holding portion 53. As a result, as described above, the filter holding portion 53 holds the filter 70 in the internal space of the casing 50 parallel to the central axis 90.

[0054] When the filter 70 is housed in the internal space of the casing 50 and the lid 60 is attached to the casing 50, one axial end of the filter 70 adheres tightly to the other axial end face of the lid 60 via the first packing 71. Also, when the filter 70 is housed in the internal space of the casing 50 and the lid 60 is attached to the casing 50, the other axial end of the filter 70 adheres tightly to the bottom surface 521 of the casing 50 via the second packing 72. As a result, the internal space of the casing 50 is divided by the filter 70 into an outer space and an inner space.

[0055] Furthermore, when the filter 70 is housed in the internal space of the casing 50 and the lid 60 is attached to the casing 50, the inlet 510 provided on the inner circumferential surface 511 of the casing 50 is located radially outward from the filter 70. That is, the inlet 510 is located in the outer space of the filter 70. Also, when the filter 70 is housed in the internal space of the casing 50 and the lid 60 is attached to the casing 50, the outlet 520 provided on the bottom surface 521 of the casing 50 is located radially inward from the filter 70. That is, the outlet 520 is located in the inner space of the filter 70. However, if the structure of the filter 70 is different from the above, the outlet 520 may open onto the inner circumferential surface 511 of the casing 50, as long as it is located in the inner space of the filter 70. That is, the outlet 520 may open onto the bottom surface 521 or the inner circumferential surface 511 of the casing 50.

[0056] The dust-containing gas drawn from the storage tank 10 into the airflow circulation path 31 flows into the space outside the filter 70 in the internal space of the casing 50 via the upstream connecting pipe 91 and inlet 510 of the filter unit 32. In other words, the inlet 510 allows the dust-containing gas to flow into the space outside the filter 70. The dust contained in the gas is then filtered by the filter 70, and only the gas flows into the internal space of the filter 70 through the filter holes formed on the surface of the filter 70. Furthermore, the gas that has flowed into the internal space of the filter 70 flows out from the internal space of the filter 70 to the external space of the casing 50 via the outlet 520 and the downstream connecting pipe 92. In other words, the outlet 520 allows the gas that has passed through the filter 70 to flow out from the internal space of the filter 70. In other words, the filter unit 32 is capable of filtering dust in the gas with the filter 70 and allowing the gas that has passed through the filter 70 to flow out.

[0057] A lid holder 54 is fixed to one axial end of the filter holder 53. The lid holder 54 has a hollow structure. A small opening, a small opening 540, is formed on the axial end face of the lid holder 54. The small opening 540 communicates with the hollow portion of the lid holder 54.

[0058] The lid 60 is a flat plate-shaped member that covers a large opening 550, which is a large opening at one end of the casing 50 on one axial side. The lid 60 has a mounting portion 61. The mounting portion 61 has a handle portion 611 and an engaging portion 612. The handle portion 611 and the engaging portion 612 are connected to each other in the axial direction. The handle portion 611 is a so-called "knob" that protrudes to one side in the axial direction. The engaging portion 612 protrudes in a T-shape to the other side in the axial direction. The tip of the engaging portion 612 passes through a small opening 540 of the lid holding portion 54 and is located in the hollow portion of the lid holding portion 54. As a result, the lid 60 has a so-called "turn-lock structure" that allows it to be attached to and detached from the casing 50 by rotating the handle portion 611 in the circumferential direction and changing the circumferential angle of the engaging portion 612. However, the lid 60 may be detachable from the casing 50 by other structures such as a bolt and nut fastening structure or a clip fitting structure. When the lid 60 is attached to the casing 50, the peripheral edge of the lid 60 is in close contact with one axial end of the casing 50 via the third packing 62.

[0059] Figure 7 is a partial perspective view illustrating the structure of the protective plate holder 55 and the protective plate 80. In Figure 7, the casing 50 is shown as a dashed line for ease of understanding. Figure 8 is a partial longitudinal cross-sectional view of the lower part of the filter unit 32 as viewed from position AA in Figure 3. As shown in Figures 7 and 8, the protective plate holder 55 has a first axial extension 551, a second axial extension 552, and a connecting portion 553. The first axial extension 551, the second axial extension 552, and the connecting portion 553 each extend substantially horizontally and in a flat plate shape. However, the first axial extension 551, the second axial extension 552, and the connecting portion 553 do not overlap radially with the inlet 510.

[0060] The first axial extension portion 551 and the second axial extension portion 552 are each fixed to the inner circumferential surface 511 of the casing 50, for example, by adhesive or welding. When the filter unit 32 is viewed horizontally from one axial side, the first axial extension portion 551 is located to the right of the inlet 510 and extends in the axial direction. When the filter unit 32 is viewed horizontally from one axial side, the second axial extension portion 552 is located to the left of the inlet 510 and extends in the axial direction. In other words, when the casing 50 is viewed in the axial direction, the protective plate holding portion 55 is located on the side of the inlet 510 and extends in the axial direction.

[0061] The connecting portion 553 extends in a direction perpendicular to the axial direction on the other axial side of the inlet 510. The connecting portion 553 connects the first axial extension portion 551 and the second axial extension portion 552. As a result, as shown in Figures 7 and 8, an arc-shaped space 500 is formed in the internal space of the casing 50 on the side closer to the inlet 510 than the protective plate holding portion 55. The arc-shaped space 500 is the space enclosed by the protective plate holding portion 55 and the inner circumferential surface 511 of the casing 50.

[0062] The protective plate 80 in this embodiment is a member that extends substantially horizontally and in a flat shape. That is, the protective plate 80 in this embodiment is flat. By making the protective plate 80 flat, it can be easily manufactured. This reduces the manufacturing cost of the protective plate 80. The protective plate 80 is formed from a metal such as stainless steel or iron. The protective plate 80 may also be formed by applying a blackening treatment to the surface of a steel material for rust prevention, similar to the casing 50. A tab 81 is provided at one end of the protective plate 80 on the axial side, allowing an operator to easily grasp and move the protective plate 80.

[0063] As shown in Figures 7 and 8, the protective plate 80 is positioned in the arc-shaped space 500. That is, the protective plate 80 is positioned along a portion of the inner circumferential surface 511 of the casing 50. When viewed radially, the outer shape of the protective plate 80 is smaller than the outer shape of the protective plate holder 55. As a result, the protective plate 80 is axially movable radially inward from the inner circumferential surface 511 of the casing 50 and radially outward from the protective plate holder 55. That is, the protective plate 80 is axially movable between the inner circumferential surface 511 of the casing 50 and the protective plate holder 55. In this embodiment, the protective plate 80 is also axially movable above the inner circumferential surface 511 of the casing 50 and below the protective plate holder 55. An operator can pull the tab 81 of the protective plate 80 to shift the protective plate 80 axially to one side of the arc-shaped space 500. Furthermore, the worker can press the tab 81 of the protective plate 80 to position the protective plate 80 in the arc-shaped space 500, so that it faces the inlet 510.

[0064] When the protective plate 80 and the inlet 510 are viewed radially, the outer shape of the protective plate 80 is sufficiently larger than the outer shape of the inlet 510. As a result, when the protective plate 80 faces the inlet 510 radially, when the protective plate 80 and the inlet 510 are viewed radially, the inlet 510 completely overlaps the protective plate 80 radially. That is, when the protective plate 80 faces the inlet 510 radially, the protective plate 80 covers the space radially inside the inlet 510. As a result, when the protective plate 80 faces the inlet 510 radially, the dust-containing gas (which may be at a high temperature) that has flowed into the internal space of the casing 50 through the inlet 510 first collides with the protective plate 80, thus preventing it from directly colliding with the filter 70. In addition, since the dust-containing gas collides with the protective plate 80 and is dispersed, it is prevented from colliding with specific parts of the filter 70. As a result, damage to the filter 70 and clogging can be suppressed.

[0065] Furthermore, since the protective plate 80 is supported by the inner circumferential surface 511 of the casing 50, when the protective plate 80 faces the inlet 510 radially, there is a gap d between the protective plate 80 and the inlet 510 in the radial direction. As a result, the gas containing dust flows into the internal space of the casing 50 without being obstructed by the protective plate 80 after passing through the inlet 510. The incoming gas containing dust then flows through one axial end or the other axial end of the arc-shaped space 500 into the space radially inward from the protective plate 80 and the protective plate holder 55.

[0066] Furthermore, as shown in Figure 7, the protective plate holder 55 has upper recesses 555R and 555L. The upper recess 555R is the portion that is recessed from the right end of the first axial extension 551 toward the left when the protective plate holder 55 is viewed horizontally from one axial side. The upper recess 555L is the portion that is recessed from the left end of the second axial extension 552 toward the right when the protective plate holder 55 is viewed horizontally from one axial side.

[0067] Furthermore, as shown in Figure 7, the protective plate 80 has lower recesses 82R and 82L. The lower recess 82R is the portion that is recessed from the right end of the protective plate 80 toward the left when the protective plate 80 is viewed horizontally from one side in the axial direction. The lower recess 82L is the portion that is recessed from the left end of the protective plate 80 toward the right when the protective plate 80 is viewed horizontally from one side in the axial direction.

[0068] When the protective plate 80 faces the inlet 510 radially, the upper recess 555R of the protective plate holding portion 55 overlaps radially with the lower recess 82R of the protective plate 80. As a result, the inlet 510, which is radially outward from the protective plate 80, and the space radially inward from the protective plate holding portion 55 are connected. That is, as shown in Figure 8, the gap between the lower recess 82R and the inner circumferential surface 511 of the casing 50, and the gap between the upper recess 555R and the inner circumferential surface 511 of the casing 50 form a ventilation hole 560R that connects the space radially inward from the protective plate 80 with the inlet 510.

[0069] Furthermore, when the protective plate 80 faces the inlet 510 radially, the upper recess 555L of the protective plate holding portion 55 overlaps radially with the lower recess 82L of the protective plate 80. As a result, the inlet 510, which is radially outward from the protective plate 80, and the space radially inward from the protective plate holding portion 55 are connected. That is, as shown in Figure 8, the gap between the lower recess 82L and the inner circumferential surface 511 of the casing 50, and the gap between the upper recess 555L and the inner circumferential surface 511 of the casing 50 form a ventilation hole 560L that connects the space radially inward from the protective plate 80 with the inlet 510.

[0070] In other words, when the protective plate 80 faces the inlet 510 radially, the filter unit 32 further has vent holes 560R and 560L on the side of the inlet 510 that connect the inlet 510 to a space radially inward of the protective plate 80. This allows the gas containing dust that has flowed into the internal space of the casing 50 through the inlet 510 to flow more smoothly through the vent holes 560R and 560L to the space radially inward of the protective plate 80.

[0071] As described above, in this embodiment, the dust-containing gas that flows into the arc-shaped space 500 in the internal space of the casing 50 via the inlet 510 flows into the space radially inward of the protective plate 80 through the axial end of the arc-shaped space 500, the other axial end of the arc-shaped space 500, the ventilation hole 560R, or the ventilation hole 560L. In other words, the axial end of the arc-shaped space 500, the other axial end of the arc-shaped space 500, the ventilation hole 560R, and the ventilation hole 560L are "communication points" that connect the space radially inward of the protective plate 80 with the space radially outward of the protective plate 80.

[0072] Furthermore, the area of ​​one axial end of the arc-shaped space 500, the area of ​​the other axial end of the arc-shaped space 500, the cross-sectional area of ​​the ventilation hole 560R, and the cross-sectional area of ​​the ventilation hole 560L each constitute the "communication area" of the communication point, which connects the space radially inside the protective plate 80 with the space radially outside the protective plate 80, respectively. When the protective plate 80 faces the inlet 510 radially, the sum of the communication areas of these communication points is greater than the opening area of ​​the inlet 510 on the inner circumferential surface 511 of the casing 50. As a result, the gas containing dust that flows into the internal space of the casing 50 through the inlet 510 can flow more smoothly through these communication points to the space radially inside the protective plate 80 without accumulating in the arc-shaped space 500.

[0073] When the drying apparatus 1 having such a filter unit 32 is repeatedly driven, dust may adhere to or accumulate in the internal space of the casing 50, mainly around the inlet 510. For this reason, it is necessary to remove the lid 60 at regular intervals to remove this dust. It may also be necessary to remove and clean or replace components such as the filter 70. In this embodiment, the inlet 510 can be exposed by removing the lid 60 by itself and sliding the protective plate 80, which is separate from the lid 60, in the axial direction. This makes it easy to remove dust that has adhered to or accumulated around the inlet 510, and to perform maintenance work such as cleaning the inside of the casing 50 and replacing components. Furthermore, it is possible to suppress the scattering of dust when performing these operations.

[0074] <3. Variant> Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment.

[0075] Figure 9 is a longitudinal cross-sectional view of the filter unit 32 according to the first modified example, cut by a plane perpendicular to the central axis 90. However, the protective plate holding portion 55 is not shown in Figures 9 to 11, which will be described later. As shown in the modified example of Figure 9, the protective plate 80 may have a tray shape in which the ends 83R and 83L of the protective plate 80 are inclined toward the central axis 90. This allows the protective plate 80 to hold dust when it is located at the bottom of the internal space of the casing 50, similar to the above embodiment. As a result, dust can be collected more easily when performing maintenance work such as removing dust that has adhered to or accumulated near the inlet 510.

[0076] Figure 10 is a longitudinal cross-sectional view of the filter unit 32 according to the second modified example, cut by a plane perpendicular to the central axis 90. As shown in the modified example in Figure 10, the protective plate 80 may have a curved plate shape that follows the inner circumferential surface 511 of the casing 50. By giving the protective plate 80 such a shape, the protective plate 80 can be easily manufactured. This reduces the manufacturing cost of the protective plate 80.

[0077] Figure 11 is a longitudinal cross-sectional view of the filter unit 32 according to the third modified example, cut by a plane perpendicular to the central axis 90. As shown in the modified example in Figure 11, the protective plate 80 may have a labyrinth structure in which multiple members (in the modified example in Figure 11, multiple members 85 that are substantially horizontal and spread out in a flat plate shape) are arranged while overlapping each other radially. This disperses the flow of gas that has entered the internal space of the casing 50 through the inlet 510, or further reduces the flow velocity of the gas, so that it can reach the filter 70. This further reduces the load on the filter 70. The protective plate 80 may also have stepped shapes or the like to disperse the flow of gas that has entered the internal space of the casing 50 through the inlet 510, or further reduce the flow velocity of the gas.

[0078] Furthermore, in the above embodiment, upper recesses 555R and 555L were provided in the protective plate holding portion 55 and lower recesses 82R and 82L were provided in the protective plate 80 in order to form ventilation holes 560R and 560L that connect the space radially inward of the protective plate 80 with the inlet 510. However, punching holes and / or mesh holes may be provided in the protective plate holding portion 55 and / or the protective plate 80 in order to form ventilation holes that connect the space radially inward of the protective plate 80 with the inlet 510.

[0079] Furthermore, in the above embodiments and modifications, the filter unit 32 was used in a drying apparatus 1 that dries powders and granules with heated dry gas. However, the filter unit 32 may also be used in devices that transport powders and granules by airflow, or in devices that perform processing other than drying using airflow.

[0080] Furthermore, in the above embodiment, a transport blower and a drying blower were used as the airflow source. However, instead of these, compressed air or gas cylinders may be used to generate airflow.

[0081] Furthermore, the detailed configuration of the drying apparatus, including the filter unit, may differ from the configuration shown in the figures of this application. For example, the order in which the equipment installed along the airflow circulation path is arranged may differ from that shown in Figure 1, and some equipment, such as the moisture adsorption unit, may be omitted.

[0082] Furthermore, the drying apparatus may be designed to process powders and granules other than resin pellets. For example, instead of resin pellets, it may process powders and granules used in various fields such as pharmaceuticals, chemical products, food products, and building materials. The dust contained in the gas that passes through such an apparatus may be collected by a filter unit.

[0083] Furthermore, the elements that appear in the above embodiments and modifications may be combined as appropriate, to the extent that no contradictions arise. [Explanation of Symbols]

[0084] 1 Drying device 9. Resin pellets 10 Storage tanks 16 Suction port 17 Air outlet 30 Airflow circulation mechanism 31 Airflow circulation path 32 filter units 33 Cooler 34 Drying blower 35 Moisture adsorption unit 36 Heating section 40 Control Unit 50 Casing 51 Side section (of the casing) 52 Bottom plate (of the casing) 53 Filter holding section 54 Lid holding part 55 Protective plate holding part 60 Lid 61 Mounting part 70 filters 71 First packing 72. Second packing 80 Protection plate 81 tabs 85 components 90 center axis 500 Arc-shaped space 510 Inlet 511 Inner surface (of the casing) 520 Outlet 521 Bottom (of the casing) 551 (Protective plate) First axial extension 552 Second axial extension (of the protective plate) 553 (Connecting part of protective plate) 560L ventilation holes 560R ventilation holes d gap

Claims

1. A filter unit capable of filtering dust in a gas using a filter and discharging the gas that has passed through the filter, A bottomed casing extending cylindrically along the central axis around the central axis, The filter, housed in the internal space of the casing, has multiple filter holes with a diameter smaller than the dust particles, and extends in a cylindrical shape parallel to the central axis, A lid that covers the opening of the casing, Within the internal space of the casing, a protective plate is arranged along a part of the inner circumferential surface of the casing, It has, The internal space of the casing is divided by the filter into an external space and an internal space of the filter. The casing is, Within the internal space of the casing, a filter holding portion holds the filter parallel to the central axis, An inlet is provided which opens on the inner circumferential surface of the casing and allows the gas containing the dust to flow into the outer space of the filter, An outlet opening on the bottom surface or inner surface of the casing, which allows the gas that has passed through the filter to flow out from the inner space of the filter, When the casing is viewed in the axial direction, it has a protective plate holding portion located on the side of the inlet and extending in the axial direction, It has, The protective plate is movable in the axial direction between the inner circumferential surface of the casing and the protective plate holding portion. A filter unit in which, when the protective plate faces the inlet radially, the protective plate covers the space radially inside the inlet and has a gap radially between it and the inlet.

2. A filter unit according to claim 1, The aforementioned protective plate is flat, in the filter unit.

3. The filter unit according to claim 2, When the protective plate faces the inlet radially, a vent hole is provided on the side of the inlet that connects the space radially inward of the protective plate with the inlet. A filter unit further comprising the following.

4. The filter unit according to claim 3, A filter unit in which, when the protective plate faces the inlet in the radial direction, the total area of ​​the communication points that connect the space radially inside the protective plate with the space radially outside the protective plate is greater than the opening area of ​​the inlet.

5. A filter unit according to claim 1, The protective plate is a filter unit having a labyrinth structure in which multiple members are arranged while overlapping each other in the radial direction.

6. A filter unit according to claim 1, The protective plate is a filter unit having a tray shape in which its end is inclined toward the central axis.

7. A filter unit according to claim 1, The protective plate is a filter unit having a curved plate shape that conforms to the inner circumferential surface of the casing.

8. A filter unit according to any one of claims 1 to 7, The aforementioned dust is a filter unit containing resin pellets, which are raw materials for resin molded products.

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