JP2013128902A - Dust collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dust collector which is made compact and made to have a high dust collection rate and from which mine dust is not discharged accidentally together with gas.SOLUTION: In the dust collector 10, an isolation plate 20 is arranged between the bottom surface 12c of a cylindrical part 12 and the opening 16a of an exhaust port 16. On the inner wall surface 12a of the cylindrical part 12 above the isolation plate 20, a plurality of collection plates 22 are arranged while having an angle in the direction opposite to such a direction that the gas made to flow from an intake port 14 is whirled in the cylindrical part 12. The mine dust is made to collide with the inner wall surface 12a of the cylindrical part 12 or the collection plates 22 and fall in a dust collection space 24 by gravity. Since the isolation plate 20 prevents the mine dust, which is accumulated in the dust collection space 24, from being sucked in the exhaust port 16, the dust collector 10 is made to have the high dust collection rate and can prevent the mine dust from being discharged accidently.

Description

  The present invention is a cyclone-type dust collector (hereinafter sometimes simply referred to as “dust collector”) that removes and collects solids such as dust (hereinafter simply referred to as “dust”) in the gas. About.

  Cyclone-type dust collectors have a simple structure and can separate gas containing dust into dust and gas, so they are widely used in all fields where dust is generated. Improvements have been made. Examples of the dust collector include the following.

Shoko 59-53860 JP-A-9-155239 JP2010-184165

In Patent Document 1, a gas intake port is provided in the tangential direction of the upper portion of the cylindrical portion of the dust collector, and a gas exhaust port is provided in the central portion of the upper surface, and is tapered to be connected to the lower portion of the cylindrical portion. Shown is a general dust collecting device composed of a conical part and a dust collecting box that collects dust connected to the lower part of the conical part, and fins that are protrusions are provided on the inner wall surface of this dust collecting box It is described.
The principle of such a dust collector is that a high-pressure gas flowing from the intake port is caused to flow along the inner wall surface of the cylindrical portion, thereby causing a downward swirling airflow, pressing the dust against the wall surface using centrifugal force, and friction By gradually reducing the speed of dust, the dust falling along the wall surface of the cone portion by gravity is collected in a dust collection box below the cone portion. Since the gas flow inside the cyclone type dust collector during operation is well known, a detailed description is omitted, but a brief description is as follows. The gas flowing into the dust collector from the intake port flows along the inner wall surface of the cylindrical part and at the same time tries to diffuse into the dust collector. It will go down in the device. Moreover, coupled with the fact that gravity acting on the dust contained in the gas acts downward, the airflow becomes a downward swirling airflow along the inner wall surface of the dust collector, and reaches the lower part of the dust collector Or in the middle, it turns into an upward swirling airflow flowing in the center of the dust collector. Therefore, the gas exits from the exhaust port provided in the central portion of the upper surface of the cylindrical portion of the dust collector. The longer the conical part used in the dust collector, the faster the gas swirl speed and the function of increasing the centrifugal force, but it contributes to the problem that the size of the dust collector increases accordingly. .
Then, the dust collector which the height of the dust collector without a cone part like the cited reference 2 was made low is proposed. According to the cited document 2, the resistance caused by increasing the gas turning speed by eliminating the conical part and providing the partition plate provided with the air holes between the cylindrical part and the dust collection box having a larger diameter than the cylindrical part. It is said that the dust collector can be reduced in size.
However, even the dust collector as in the cited document 2 requires the height of the cylindrical portion and the dust collection box, and part of the dust rides on the rising swirl airflow or accumulates in the dust collection box. There is a problem that a part of the dust is sucked in the direction of the cylindrical portion where the pressure is low, passes through the hole of the partition plate, and is discharged to the outside from the exhaust port.
Further, in Cited Document 3, there is a dust collecting device including a cylindrical portion, which is a shield that prevents dust accumulated on the bottom of the cylindrical portion from being discharged from the exhaust port in the vicinity of the inside of the bottom surface of the cylindrical portion. A small dust collector having a high dust collection rate provided with a member is disclosed.
However, in the dust collector of Cited Document 3, it is difficult to drop the dust below the shielding member. This is because when dust is a fine particle, it is difficult to receive centrifugal force, so it cannot be pressed against the wall surface of the cylindrical part and the speed can be reduced sufficiently by friction, and it rotates along the wall surface of the cylindrical part. Because it will continue. As a result, there is a problem that a part of such dust rides on the upward swirling airflow and is discharged to the outside from the exhaust port.

  In view of the above-described problems of the prior art, an object of the present invention is to provide a dust collector that is compact, has a high dust collection rate, and does not accidentally discharge dust together with gas.

  The present invention relates to a cylindrical portion having an intake port tangentially connected to the upper portion of the side wall, a cylindrical exhaust port provided at the center of the upper surface, an outer diameter of the exhaust port, and an inner diameter of the cylindrical portion. A shield plate having a small diameter and a collecting plate, and the shield plate is provided between the bottom surface of the cylindrical portion and the opening of the exhaust port, and the collecting plate is located above the shield plate. The above problem has been solved by a dust collector characterized in that the inner wall surface of the cylindrical portion is provided with an angle in a direction opposite to the swirling direction of the gas flowing in from the intake port.

  Further, as in claim 2, it is preferable that the collecting plate is provided within a range of 45 to 60 degrees between the normal to the inner diameter of the cylindrical portion and the collecting plate. .

  Moreover, it is preferable that it is a triangular shape which the width of a collection board becomes wide toward the downward direction of a cylindrical part like Claim 3.

  Moreover, it is preferable to make it the structure which the shielding board protrudes upwards toward the center of a cylindrical part like Claim 4, and the bottom face of a cylindrical part is toward the center of a cylindrical part like Claim 5. It is good to set it as the structure which protrudes upwards.

  Further, as in claim 6, the dust discharge port is provided on the side wall of the cylindrical portion below the blocking plate in the tangential direction of the cylindrical portion in the same direction as the swirling direction of the gas flowing in from the intake port. Is preferred.

  According to a seventh aspect of the present invention, the collecting plate is provided on the blocking plate with a gap between the inner wall surface of the cylindrical portion, the blocking plate is pivotally supported by the shaft, and the swirl of the gas flowing in from the intake port It is preferable that the direction of rotation is slower than the turning speed of the gas.

  According to the present invention, the blocking plate having a diameter equal to or larger than the outer diameter of the exhaust port and smaller than the inner diameter of the cylindrical portion is provided between the bottom surface of the cylindrical portion and the opening portion of the exhaust port, and the collecting plate is The inner wall surface of the cylindrical portion above the blocking plate is provided with an angle in a direction opposite to the swirling direction of the gas flowing in from the intake port, so that the high-pressure gas flowing from the intake port The contained dust collides with the collecting plate when it is pressed against the inner wall surface by the centrifugal force and moves along the inner wall surface or when moving toward the inner wall surface. The dust that collides with the collecting plate loses its speed, falls along the wall surface due to gravity, and collects between the bottom surface of the cylindrical portion and the lower surface of the shielding plate from the gap between the inner wall of the cylindrical portion and the shielding plate. Accumulate in the dust space. In this way, the speed of the dust can be lost by colliding the dust against the collecting plate without reducing the speed of the dust by pressing against the inner wall surface and friction with the inner wall surface, so that it is difficult to receive centrifugal force. Even fine particles can be reliably guided to the dust collection space. That is, the dust collection rate can be significantly increased.

  According to a second aspect of the present invention, the collecting plate is provided on the inner wall surface of the cylindrical portion so that the angle between the normal to the inner diameter of the cylindrical portion and the collecting plate is within a range of 45 degrees to 60 degrees. Is preferred. This is because if the angle is less than 45 degrees, the resistance to the collection plate by the swirling airflow increases, which may cause unexpected damage to the collection plate. If the angle is more than 60 degrees, the dust collection rate decreases. In addition, because the blocking plate prevents the dust collected in the dust collection space from being sucked upward from the blocking plate in a low pressure state, the dust is discharged together with the gas exhausted from the exhaust port. Can be prevented. Further, unlike the conventional dust collector, the dust collector of the present invention does not need to be provided with a conical portion or a dust collection box, so that the height dimension can be made compact.

  Further, as described in claim 3, by making the width of the collecting plate into a triangular shape that becomes wider toward the bottom of the cylindrical portion, the resistance to the collecting plate due to the downward swirling airflow can be reduced, and Breakage of the collecting plate can be prevented.

  Further, as described in claim 4, when the blocking plate protrudes upward toward the center of the cylindrical portion, an excessive ascending swirling air flow in the dust collector is obtained as compared with a flat blocking plate. Generation can be suppressed, and dust can be reliably prevented from being accidentally discharged from the exhaust port.

  In addition, as described in claim 5, when the bottom surface of the cylindrical portion protrudes upward toward the center of the cylindrical portion, the dust accumulated in the dust collection space is centered in the dust collection space of the cylindrical portion. It can prevent moving to a part.

  According to a sixth aspect of the present invention, the dust discharge port is provided on the side wall of the cylindrical portion below the blocking plate in the tangential direction of the cylindrical portion in the same direction as the swirling direction of the gas flowing in from the intake port. If it is set as a structure, the dust which collected in the dust collection space can be collected in a discharge port using the downward swirl | vortex airflow and centrifugal force which arise in a dust collector, and can be discharged | emitted out of a dust collector as it is.

  According to a seventh aspect of the present invention, the collecting plate is provided on the blocking plate with a gap between the inner wall surface of the cylindrical portion, the blocking plate is pivotally supported by the shaft, and the swirl of the gas flowing in from the intake port If the collecting plate moves along the inner wall surface of the cylindrical portion if it rotates in the direction slower than the gas swirling speed, the collecting plate is provided on the inner wall surface of the cylindrical portion. As compared with the above, dust can be prevented from being clogged between the collecting plate and the inner wall surface of the cylindrical portion. At this time, since the collecting plate rotates in the same direction as the swirling direction of the gas flowing in from the intake port, the resistance to the collecting plate by the descending swirling airflow can be further reduced.

The longitudinal cross-sectional view of the front view of the dust collector of 1st Embodiment of this invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. The longitudinal cross-sectional view of the front view of the dust collector of 2nd Embodiment of this invention. FIG. 4 is a sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. The longitudinal cross-sectional view of the front view of the dust collector of 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. However, the present invention is not limited to this embodiment.

  FIG. 1 shows a dust collector 10 according to a first embodiment of the present invention. The dust collector 10 has a cylindrical portion 12, an intake port 14 is connected to the upper portion of the side wall of the cylindrical portion 12 in the tangential direction of the cylindrical portion 12, and a central portion of the upper surface 12 b of the cylindrical portion 12 is A cylindrical exhaust port 16 is provided. Further, a blocking plate 20 is provided between the bottom surface 12 c of the cylindrical portion 12 and the opening portion 16 a of the exhaust port 16, and a plurality of collections are provided on the inner wall surface 12 a of the cylindrical portion 12 above the blocking plate 20. A plate 22 is provided. Further, the cylindrical portion 12 has a dust collection space 24 between the shielding plate 20 and the bottom surface 12c, and a dust discharge port 18 is provided in the tangential direction of the side wall of the cylindrical portion 12 below the shielding plate 20. Yes.

  If the position of the blocking plate 20 is too close to the opening 16a of the exhaust port 16, the gas is not exhausted well. Further, since there is a gap 24a between the blocking plate 20 and the inner wall surface 12a, the dust colliding with the inner wall surface 12a and the collecting plate 22 falls into the dust collection space 24 through the gap 24a. become. The blocking plate 20 is attached to the bottom surface 12c by a leg portion 21.

  The collection plate 22 has a quadrangular shape, and as shown in FIG. 2, the plurality of collection plates 22 are attached in an angled direction in the same direction with respect to the inner wall surface 12 a of the cylindrical portion 12. The angled direction is a direction opposite to the direction in which the gas flowing from the intake port 14 (see FIG. 1) swirls in the cylindrical portion 12. By doing so, the resistance applied to the collection plate 22 by the downward swirling airflow of the gas flowing from the intake port 14 can be reduced as compared with the case where the collection plate 22 is not angled with respect to the inner wall surface 12a, that is, when it is attached at a right angle. It can be made small, and the damage of the collecting plate 22 due to the resistance can be prevented. In addition, the attachment angle with respect to the inner wall surface 12a of the collection board 22 is the angle between the normal X with respect to the internal diameter of the cylindrical part 12, and the collection board 22 from the relationship between the resistance concerning the collection board 22, and a dust collection rate. It is preferable to set α to 45 degrees to 60 degrees. This is because if the angle α is smaller than 45 degrees, the resistance to the collecting plate 22 increases, and if it is larger than 60 degrees, the dust collection rate decreases. In addition, the larger the size of the collecting plate 22, the larger the area where the dust collides, but since the resistance applied to the collecting plate 22 is increased, it hinders the downward swirling airflow of the gas, and the collecting plate. 22 is likely to be damaged. On the other hand, when the collecting plate is made smaller, the resistance applied to the collecting plate 22 can be reduced, but the area where the dust collides becomes smaller and the dust collecting rate becomes lower. Further, although a single collecting plate 22 may be considered, at least four on the inner peripheral surface 12a of the cylindrical portion 12 every 90 degrees from the viewpoint of improving the dust collection rate, preferably as shown in FIG. In addition, 12 sheets are preferably provided every 30 degrees.

  The discharge port 18 shown in FIG. 1 is attached in the tangential direction of the side wall of the cylindrical portion 12 below the blocking plate 20. In this case, the tangential direction is the direction of the downward swirling airflow of the gas flowing from the intake port 14. Is in the same direction. When the dust collector 10 is in operation, when the gas flows from the intake port 14 and starts turning, the air in the dust collector 10 also starts turning in the same direction. Accordingly, a swirling airflow is generated in the dust collection space 24. By utilizing the swirling airflow and centrifugal force generated in the dust collection space 24, the dust accumulated in the dust collection space 24 can be collected in the discharge port 18, so that the dust can be automatically discharged from the discharge port 18. . Note that a rotary valve (not shown) is connected to the tip of the discharge port 18 so that gas can be prevented from being exhausted from the discharge port 18, so that only dust accumulated in the dust collection space 24 can be prevented. Can be taken out from the outlet 18. In the embodiment of the present invention, the configuration in which the discharge port 18 is provided is described. However, the dust collection space 24 portion of the cylindrical portion 12 can be attached or detached, or a dust outlet is provided in a part of the bottom surface 12c. Needless to say, well-known dust discharging means can be applied.

  FIG. 3 shows a dust collector 10a according to a second embodiment of the present invention. Since the basic structure of the dust collector 10a is the same as that of the dust collector 10, description of the same part is abbreviate | omitted.

  The collection plate 22a of the dust collector 10a has a triangular shape whose width becomes wider toward the lower side of the cylindrical portion 12. By carrying out like this, compared with the square-shaped collection board 22 like the dust collector 10, coexistence of making resistance to the collection board 22a by a descending swirl air flow small, and raising the dust collection rate of dust. Can be achieved. That is, the effect of centrifugal force can be maximized without interfering with the downward swirling airflow of the gas flowing from the intake port 14.

  Further, the blocking plate 20 a and the bottom surface 12 c protrude upward toward the center of the cylindrical portion 12. By setting it as such a structure, generation | occurrence | production of the excessive ascending swirl | vortex airflow in the dust collector 10a can be suppressed compared with the thing with the planar shielding board 20a, and dust is discharged | emitted from the exhaust port 16 accidentally. This can be surely prevented. Further, by adopting a configuration like the bottom surface 12 c, dust accumulated in the dust collection space 24 can be prevented from moving to the central portion in the dust collection space 24 of the cylindrical portion 12, and the swirl in the dust collection space 24 can be prevented. It becomes easy to collect dust at the discharge port 18 by utilizing the airflow and centrifugal force. In the dust collector 10 a, both the blocking plate 20 a and the bottom surface 12 c protrude upward toward the center of the cylindrical portion 12, but either the blocking plate 20 a or the bottom surface 12 c is at the center of the cylindrical portion 12. It is good also as a structure which protrudes upwards.

  Further, in the dust collector 10a, the blocking plate 20a is provided between the bottom surface 12c of the cylindrical portion 12 and the opening 16a of the exhaust port 16 by connecting one end of the collecting plate 22a. Even if the leg portion 21 is not provided like the shielding plate 20 in the dust collector 10, the point is that the shielding plate 20 a may be provided between the bottom surface 12 c and the opening 16 a of the exhaust port 16.

Next, the operation of the dust collector of the present invention will be described with reference to FIGS.
In FIG. 3, the arrow represents the flow of gas flowing through the dust collector 10a during operation. The gas containing dust flowing from the air inlet 14 flows along the inner wall surface 12a of the cylindrical portion 12 and simultaneously diffuses into the cylindrical portion 12, but the upper surface 12b of the cylindrical portion 12 becomes a wall, so that the cylinder Heading below section 12. Further, coupled with the action of gravity acting on the dust contained in the gas, the airflow becomes a downward swirling airflow toward the bottom surface 12 c of the cylindrical portion 12. At the same time, the air inside the cylindrical portion 12 starts to turn in the same direction as the downward swirling airflow, so that the swirling airflow is also generated in the dust collection space 24. Further, since the descending swirl airflow turns into the ascending swirl airflow at the central portion in the cylindrical portion 12 at the central portion on the blocking plate 20a of the cylindrical portion 12, the gas is finally exhausted from the exhaust port 16. become. At this time, the pressure above the blocking plate 20a in the cylindrical portion 12 is lower than that of the dust collection space 24. However, since there is the blocking plate 20a, dust accumulated in the dust collection space 24 is exhausted from the exhaust port 16. Can be prevented. Note that a blower is used to send gas to the intake port or to suck it from the exhaust port. However, since this is a well-known technique in a dust collector, its description is omitted.

  As shown in FIG. 4, the dust D (only a part of which is illustrated) moves in the direction of the arrow attached to the dust D by the action of the downward swirling airflow and the centrifugal force. The dust D collides with the collecting plate 22a or is pressed against the inner wall surface 12a of the cylindrical portion 12 and moves while decelerating along the inner wall surface 12a. Here, since the collecting plate 22a is attached to the inner wall surface 12a of the cylindrical portion 12 with an angle in a direction opposite to the direction in which the gas turns as indicated by the arrow, the dust D is collected. A large amount is collected in the β portion between the collecting plate 22a and the inner wall surface 12a. Since these dusts D lose their speed and are no longer affected by the centrifugal force, they fall by gravity to the dust collection space 24 shown in FIG. 3 through the gap 24a between the blocking plate 20a and the inner wall surface 12a.

  FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 3 and shows the state of the dust collection space 24 during operation. As shown in FIG. 5, dust D (only a part of which is dropped in the dust collection space 24 is moved in the direction of the arrow attached to the dust D on the bottom surface 12 c by the swirling airflow in the direction of the arrow. Therefore, it is collected on the inner wall surface 12a side of the cylindrical portion 12 by the action of the swirling airflow and centrifugal force. In addition, since the discharge port 18 is provided in the tangential direction of the cylindrical portion 12 in the same direction as the direction of the swirling airflow indicated by the arrow, dust D is generated in the discharge port 18 by the action of the swirling airflow and centrifugal force. It will automatically accumulate. Since the dust D accumulated in the discharge port 18 has a force directed outward from the discharge port 18, a rotary valve (not shown) is attached to the tip of the discharge port 18 to leak gas in the dust collector 10 a. By making it not, only the dust D can be discharged automatically. That is, since the dust D can be continuously discharged, the dust collector 10a can be continuously operated without requiring manual removal of the dust D by collecting the dust D in the dust collection space 24.

  Finally, FIG. 6 shows a dust collector 10b according to a third embodiment of the present invention. The dust collector 10b is provided on the blocking plate 20b with a gap between the collecting plate 22b and the inner wall surface 12a of the cylindrical portion 12. This gap is preferably as narrow as possible in order to increase the dust collection rate. The blocking plate 20b is rotatably supported by a shaft 26, and is rotated slower than the gas turning speed in the turning direction of the gas flowing in from the intake port 14 by a control means (not shown). The control means includes, for example, a gas swirl speed and motor rotation speed sensor, and a controller that can set the latter slower than the former. The shaft 26 is connected to a motor (not shown), and the shaft 26 is swung by the motor. For example, the rotation of the shaft 26 is suppressed by the resistance to the collecting plate 22b of the descending swirling airflow by using a control mechanism that rotates slower than the speed or a brake mechanism. It is only necessary that the can be rotated slower than the gas turning speed. In addition, as shown in FIG. 6, when extending the axis | shaft 26 to the exterior of the cylindrical part 12, between the axis | shaft 26 and the bottom face 12c is sealed with the sealing member which is not shown in figure. Moreover, in FIG. 6, although the shape of the bottom face 12c, the shielding board 20b, and the collection board 22b has shown the thing similar to the thing of the dust collector 10a, it is good also as a thing similar to the thing of the dust collector 10a. Good.

  Next, the state during operation of the dust collector 10b will be described. Since the gas flow is the same as in the case of the dust collectors 10 and 10a, description thereof will be omitted. First, when a gas containing dust is flowed from the intake port 14, the shaft 26 of the dust collector 10b is controlled so as to rotate slower than the swirling speed of the gas, so the dust contained in the gas is It collides with the collecting plate 22b moving along the inner wall 12a. And the dust which collided with the collection board 22b loses speed, and it accumulates in the dust collection space 24 from the clearance gap 24a between the inner wall 12a of the cylindrical part 12, and the shielding board 20b by gravity. For this reason, in the dust collector 10b, the resistance to the collection plate 22b by the downward swirling airflow can be reduced while realizing a dust collection rate equivalent to that of the dust collectors 10 and 10a. Further, since the shaft 26 rotates and the collection plate 22b moves along the inner wall 12a, dust is clogged between the collection plate 22b and the inner wall 12a as compared with the configuration of the dust collectors 10 and 10a. This can be prevented.

  As described above, according to the present invention, it is possible to provide a compact dust collector that does not require a conical portion or a dust collection box as in the conventional dust collector, and the collecting plate is an inner wall surface of the cylindrical portion. In addition, it is installed in a state where the gas flowing from the intake port is angled in a direction opposite to the direction in which the gas swirls in the dust collector, so that the dust collection rate can be significantly increased compared to the conventional one. In addition, it is possible to prevent the dust accumulated in the dust collection space from being sucked into the discharge port by the blocking plate. In addition, by providing the dust discharge port on the side wall of the cylindrical part below the blocking plate in the tangential direction of the cylindrical part in the same direction as the swirling direction of the gas flowing in from the intake port, the swirling airflow generated in the dust collection space In addition, dust can be automatically discharged out of the dust collector using the force of centrifugal force.

DESCRIPTION OF SYMBOLS 10, 10a Dust collector 12 Cylindrical part 12a Inner wall surface 12b Upper surface 12c Bottom surface 14 Intake port 16 Exhaust port 18 Outlet port 20, 20a Shut-off plate 22, 22a Collection plate 26 Axis

Claims (7)

A cylindrical portion having a suction port connected to the upper portion of the side wall in a tangential direction and a cylindrical exhaust port provided at the center of the upper surface, the outer diameter of the exhaust port being larger than the inner diameter of the cylindrical portion, and smaller than the inner diameter of the cylindrical portion A barrier plate and a collecting plate;
The blocking plate is provided between the bottom surface of the cylindrical portion and the opening of the exhaust port;
The collecting plate is provided on the inner wall surface of the cylindrical portion above the blocking plate in an angled direction in a direction opposite to the swirling direction of the gas flowing in from the intake port. To
Dust collector.   2. The dust collector according to claim 1, wherein the collection plate is provided within a range of 45 to 60 degrees between a normal to the inner diameter of the cylindrical portion and the collection plate.   The dust collector according to claim 1 or 2, wherein the collecting plate has a triangular shape in which a width of the collecting plate becomes wider toward a lower side of the cylindrical portion.   The dust collector according to claim 1, wherein the blocking plate protrudes upward toward the center of the cylindrical portion.   The dust collector according to any one of claims 1 to 4, wherein a bottom surface of the cylindrical portion protrudes upward toward a center of the cylindrical portion.   The dust discharge port is provided in the tangential direction of the cylindrical portion in the same direction as the swirling direction of the gas flowing in from the intake port on the side wall of the cylindrical portion below the blocking plate. Any dust collector. The collecting plate is provided on the blocking plate with a gap between the cylindrical wall and the inner wall surface;
The dust collector according to any one of claims 1 to 6, wherein the blocking plate is pivotally supported by a shaft and rotates in a swirling direction of the gas flowing in from the intake port at a speed lower than a swirling speed of the gas. .

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