JP7499302B2 - Attachment and airflow outlet structure - Google Patents

Description

The present invention relates to an attachment that is attached to the outlet of a blower device, and to the structure of the airflow outlet of the blower device.

Conventionally, the structure of the air outlet of a blower device has been such that a flow path is provided around the central flow path of the outlet, and a layered airflow is interposed between the airflow blown out from the central flow path and the outside air, thereby suppressing contact between the airflow blown out from the central flow path and the outside air. An example of such a blower device is the blowing structure described in Patent Document 1. In the blower device described in Patent Document 1, an airflow with a slower flow rate than the airflow blown out from the central tube is blown out around the airflow, thereby suppressing contact between the airflow blown out from the central tube and the outside air.

Patent No. 5071318

If the flow rate of the airflow blowing out from the center is small, even if the surrounding area is covered with a layered airflow, the speed of the central airflow and the distance it can reach are limited. On the other hand, if the flow rate of the airflow blowing out from the central flow path is large, the airflow that covers the surrounding area cannot be sufficiently secured, and the effect of covering it with a layered airflow is limited.

The present invention has been made to solve the above problems, and its main objective is to provide an attachment and air outlet structure that can suppress the deceleration of the blown airflow while ensuring a sufficient flow rate of the blown airflow.

The first configuration is an attachment whose rear side is attached to the airflow outlet and passes the airflow from the rear side to the front side, and has a front opening which is an opening on the front side and a rear opening which is an opening on the rear side, and is equipped with a central tube part through which the airflow can pass from the rear opening to the front opening, a limiting part which is provided around the rear opening of the central tube part and limits the passage of the airflow, and a plurality of holes provided in the limiting part and spaced apart from each other which penetrate the limiting part from the rear side to the front side.

In the first configuration, the holes penetrating the restricting portion are spaced apart from each other, so that the ratio of the airflow passing through the holes to the total airflow blown into the attachment is reduced. That is, more airflow flows into the rear opening of the central tube, and the flow rate of the first airflow, which is the airflow blown out from the front opening of the central tube, increases. On the other hand, when the holes are spaced apart from each other, a gap is created between the second airflow, which is the airflow blown out from the holes. When the outside air in the gap comes into contact with the first airflow, the first airflow may be significantly slowed down. In this regard, since the restricting portion is provided around the rear opening of the central tube, the second airflow diffuses and reaches the periphery of the front opening of the central tube. As a result, when the first airflow blows out from the front opening, the periphery of the first airflow is covered by the second airflow, and contact between the first airflow and the outside air can be further suppressed. Therefore, the flow rate of the first airflow can be secured while the deceleration of the first airflow can be suitably suppressed.

The second configuration includes, in addition to the first configuration, a guide section that guides the airflow passing through the hole toward the periphery of the front opening of the central tube section.

The second airflow blown out of the hole diffuses and reaches the periphery of the front opening of the central tube. In this case, if the second airflow diffuses excessively, it is not possible to ensure that a sufficient amount of the second airflow reaches the periphery of the front opening. In this regard, the second configuration is provided with a guide section that guides the second airflow to the periphery of the front opening of the central tube, and therefore it is possible to suppress the diffusion of the second airflow. This ensures a sufficient flow rate of the second airflow when it merges with the first airflow, and it is possible to suitably suppress the deceleration of the first airflow that occurs when the first airflow comes into contact with the outside air.

In the third configuration, in addition to the first or second configuration, the rear opening of the central tube and the rear end of the restriction section are positioned on a virtual plane perpendicular to the direction of the airflow.

In the third configuration, the airflow that reaches the rear end of the restrictor and does not pass through the hole is more likely to flow into the rear opening of the central tube. This allows the flow rate of the first airflow to be increased.

In the fourth configuration, in addition to any of the first to third configurations, the shape of the central cylinder is a truncated cone cylinder whose inner diameter decreases from the rear opening to the front opening.

Since the speed of the first airflow increases inversely proportional to the flow path area, the fourth configuration can increase the flow rate of the first airflow being blown out.

In the fifth configuration, in addition to the fourth configuration, the shape of the limiting portion is an annular plate that shares a central axis with the central tube portion.

In the fifth configuration, the second airflow blown out from the holes provided in the annular plate-shaped restricting portion becomes an annular layer that covers the entire circumference of the front opening of the central tube portion. This makes it possible to more effectively suppress the deceleration of the first airflow caused by contact between the first airflow and the outside air.

In the sixth configuration, in addition to the fifth configuration, the shape of the hole is curved along the outer circumferential surface of the central tube portion when viewed from the front.

In the sixth configuration, when the second airflow reaches the periphery of the front opening, it is easier to form a circular layer. Therefore, it is possible to more effectively suppress the deceleration of the first airflow caused by contact between the first airflow and the outside air.

In the seventh configuration, in addition to the sixth configuration, the shape of the inner end portion, which is the end portion on the central axis side of the hole, is an arc that follows the outer circumferential surface of the central cylinder portion.

In the seventh configuration, the second airflow blown out of the hole travels along the outer circumferential surface of the central tube to the periphery of the front opening. This makes it more difficult for outside air to get between the first and second airflows when the second airflow reaches the front opening, and makes it possible to more effectively suppress deceleration caused by contact between the first airflow and the outside air.

In the eighth configuration, in addition to the seventh configuration, the shape of the outer end, which is the end on the outer periphery of the hole, is an arc with a larger central angle than the inner end.

The second airflow blowing out from the holes tends to diffuse outward as it approaches the outer end, so the layer of the second airflow between the outer ends of two holes that are close in the circumferential direction tends to become thinner. In this regard, in the eighth configuration, the outer end is an arc with a larger central angle than the inner end, so the flow rate of the second airflow blowing out from the outer end side can be increased, and the thickness of the annular layer around the front opening of the central tube can be sufficiently ensured.

In the ninth configuration, in addition to the eighth configuration, the total arc length of the outer ends is greater than the circumference of the front opening.

In the ninth configuration, even if the second airflow blown out of the hole maintains its shape when it reaches the front opening, the second airflow that forms an annular layer can cover the entire circumference of the front opening. This makes it possible to more effectively suppress the deceleration caused by contact between the first airflow and the outside air.

In the tenth configuration, in addition to any of the sixth to ninth configurations, the area of the hole is approximately equal to the area between a pair of circumferentially adjacent holes when viewed from the front.

If the area of the hole becomes excessively large, the flow rate of the first airflow will decrease. In this regard, the tenth configuration can ensure a sufficient area between the holes, allowing more airflow to flow into the central tube.

The eleventh configuration includes any one of the first to tenth configurations, and further includes a vortexing section that rotates the airflow passing through the inside of the central tube section around the central axis of the central tube section.

When the airflow is a vortex, the flow speed increases toward the center of the vortex and decreases toward the end of the vortex. In this case, the end of the vortex slows down as it comes into contact with the outside air, but the center of the vortex is protected by the vortex on the end side and deceleration is suppressed. In the eleventh configuration, it is possible to make the first airflow a vortex, and since the outer periphery of the vortex is covered by the second airflow, it is possible to better maintain the speed of the center of the first airflow, which is a vortex.

In the twelfth configuration, in addition to any one of the fifth to tenth configurations, the central tube portion has a plurality of plate-shaped fins that connect the central axis and the inner peripheral surface from the front opening side to the rear opening side, and the fins are curved in the same circumferential direction.

In the twelfth configuration, curved fins are provided inside the central tube, so that the first airflow passing through the inside of the central tube can be made into a vortex that rotates around the central axis, and the speed of the first airflow on the central side can be better maintained.

The thirteenth configuration is an outlet structure that allows gas to pass from the inlet side to the outlet side, and has a front opening which is an opening on the inlet side of the gas and a rear opening which is an opening on the outlet side of the gas, and is equipped with a central tube portion through which gas can pass from the rear opening to the front opening, a limiting portion provided around the rear opening of the central tube portion to limit the passage of gas, and a plurality of holes provided in the limiting portion and spaced apart from one another that penetrate the limiting portion from the rear side to the front side.

This thirteenth configuration can achieve effects similar to those of the first configuration.

FIG. 2 is a diagram showing the overall configuration of the blower device. FIG. 2 is a perspective view of the front side of the attachment according to the first embodiment. FIG. 2 is a perspective view of the rear side of the attachment according to the first embodiment. FIG. 2 is a front view of the attachment according to the first embodiment. FIG. 2 is a rear view of the attachment according to the first embodiment. FIG. 2 is a top view of the attachment according to the first embodiment. FIG. 2 is a cross-sectional view of the attachment according to the first embodiment taken along line AA. FIG. 5 is an enlarged view of FIG. FIG. 4 is a cross-sectional view showing an airflow passing through the attachment according to the first embodiment. 4 is an enlarged front view of an airflow passing through the attachment according to the first embodiment; FIG. FIG. 11 is a front view of the attachment according to the second embodiment. FIG. 11 is a rear view of the attachment according to the second embodiment. FIG. 5 is a cross-sectional view taken along line BB of the attachment according to the second embodiment.

Each embodiment will be described below with reference to the drawings. Note that in the following embodiments, parts that are identical or equivalent to each other are given the same reference numerals in the drawings, and the explanations of the parts with the same reference numerals are incorporated herein.

First, the overall configuration of the air blowing system to which the attachment according to this embodiment is attached will be described with reference to FIG. 1. The air blowing device 100 of the air blowing system rotates a fan provided inside to generate an airflow. The airflow generated by the air blowing device 100 is supplied through a cylindrical duct 101 connected to the air blowing device 100. A plurality of openings are provided on the side of the duct 101, and a plurality of cylindrical flexible ducts 102 with bellows-shaped sides are attached to each of the openings. Since the flexible ducts 102 are bellows-shaped, the blowing direction of the airflow can be changed by bending them. The attachment 10 according to this embodiment is attached to the tip of each flexible duct 102. The inner diameter of the flexible duct 102 to which the attachment 10 according to this embodiment is attached is about 100 mm to about 150 mm, and the flow speed of the airflow passing through the flexible duct 102 is assumed to be 10 to 20 m/s. Furthermore, because the inner diameter of the flexible duct 102 and the airflow velocity are these values, the airflow blown into the attachment 10 and the airflow blown out from the attachment 10 are turbulent.

The specific structure of the attachment 10 according to this embodiment will be described with reference to Figures 2 to 6. In the following description, when the attachment 10 is attached to the tip of the flexible duct 102, the flexible duct 102 side, i.e., the side where the airflow flows into the attachment 10, will be referred to as the back side, and the opposite side, i.e., the side where the airflow blows out, will be referred to as the front side. In the following description, the front side can be referred to as the front side and the back side can be referred to as the back side, so both the direction from the front to the back and the opposite direction may be referred to as the front-to-rear direction.

The attachment 10 has a cylindrical outer tubular portion 11 with a substantially uniform thickness. The outer diameter of the outer tubular portion 11 is substantially equal to the inner diameter of the flexible duct 102 to which it is intended to be attached. On the outside of the outer tubular portion 11, a connecting tubular portion 12 is provided, which has a larger diameter than the outer tubular portion 11 and shares a common central axis. The inner diameter of the connecting tubular portion 12 is larger than the outer diameter of the flexible duct 102 to which it is intended to be attached. The front end of the connecting tubular portion 12 and the front end of the outer tubular portion 11 are located on an imaginary plane perpendicular to the central axis.

The outer tubular portion 11 and the connecting tubular portion 12 are connected at the front end of the outer tubular portion by a connecting portion 13, which is a ring of approximately uniform thickness. This connecting portion 13 is perpendicular to the central axis, and shares a common center with the outer tubular portion 11 and the connecting tubular portion 12 when viewed from the front. The inner diameter of this connecting portion 13 is equal to the inner diameter of the outer tubular portion 11, and the outer diameter of the connecting portion 13 is equal to the outer diameter of the connecting tubular portion 12.

The side of the connecting tube portion 12 is provided with a notch 14 consisting of a pair of linear holes that are approximately parallel to the central axis and of equal length, and a linear hole that connects the front ends of the pair of linear holes. One notch 14 is provided on each of the upper and lower faces of the connecting tube portion 12, at opposing positions. By providing this notch 14, a rectangular burr 15 with an open front side is provided on the upper and lower faces of the connecting tube portion 12. The tip side of this burr 15, i.e. the front side, is warped inward, i.e. toward the outer peripheral tube portion 11.

A truncated cone-shaped inlet flow passage 16 is provided on the inner circumference of the rear end of the outer tubular portion 11, with the diameter decreasing from the rear end of the outer tubular portion 11 towards the front side. This inlet flow passage 16 shares a central axis with the outer tubular portion 11, and the angle between the central axis and the generatrix of the inlet flow passage 16 is 30 degrees. The length of the inlet flow passage 16 in the front-to-rear direction is approximately half that of the outer tubular portion 11 in the front-to-rear direction. The thickness of the side surface of the inlet flow passage 16 is approximately uniform.

A flange portion 17 is provided at the tip of the introduction flow passage 16 in the shape of a circular ring plate and with a substantially uniform thickness. This flange portion 17 is perpendicular to the central axis of the outer circumferential cylindrical portion 11, and the center of the flange portion 17 coincides with the central axis of the outer circumferential cylindrical portion 17. In other words, both the inner and outer circumferences of the flange portion 17 are concentric with the outer circumferential cylindrical portion 11 when viewed from the front.

The inner circumference of the flange portion 17 is provided with a central cylinder portion 18 in the shape of a truncated cone cylinder, the diameter of which decreases from the flange portion 17 toward the front side. This central cylinder portion 18 also shares a central axis with the outer peripheral cylinder portion 11, and the angle of the generatrix of the central cylinder portion 18 with respect to the central axis is 30 degrees. The front opening 18a, which is the opening on the front side of the central cylinder portion 18, is located on the same imaginary plane as the front of the connection portion 13. The length of the central cylinder portion 18 in the front-to-rear direction is approximately half that of the outer peripheral cylinder portion 11 in the front-to-rear direction. In addition, the thickness of the side surface of the central cylinder portion 18 is approximately uniform. The rear opening 18b, which is the opening on the rear side of the central cylinder portion 18, and the rear surface of the flange portion 17 are located on a common imaginary plane perpendicular to the central axis, and the rear opening 18b of the central cylinder portion 18 and the flange portion 17 share an opening.

The flange portion 17 has a plurality of holes 19 that penetrate in the front-rear direction and are spaced apart from one another. The inner end 19a, which is the end of the hole 19 on the central axis side, is an arc that follows the outer periphery of the rear opening 18b of the central cylinder portion 18 in a front view. The inner end 19a of the hole 19 is at a constant distance from the central axis in the front-rear direction. In other words, the inner end 19a of the hole 19 is an arc-shaped curved surface that is parallel to the central axis.

The outer end 19b, which is the end on the outer periphery of the hole 19, shares a center line with the inner end 19a in a front view and is an arc with a larger central angle than the inner end 19a. This outer end 19b is linear in the front-to-rear direction and continues with the inner circumferential surface of the introduction flow passage 16. In other words, the distance from the central axis of the outer end 19b gradually decreases from the back side to the front side. Therefore, the height of the hole 19 in the direction perpendicular to the central axis gradually decreases from the back side to the front side.

The circumferential ends of the holes 19 are each a straight line connecting the inner end 19a and the outer end 19b. As described above, the central angle of the outer end 19b is larger than the central angle of the inner end 19a, so that in a front view, the intersection s1 of the imaginary lines passing through the circumferential ends of one hole 19 is closer to the hole 19 than the center s of the attachment 10.

In the hole 19 configured in this manner, the total arc length of the outer end 19b is made larger than the outer circumference of the front opening 18a of the central tube portion 18. The arc lengths of the inner end 19a and the outer end 19b are determined so that the area of the hole 19 in a front view is equal to the area sandwiched between a pair of holes 19 adjacent in the circumferential direction. Even if an error occurs in manufacturing, the areas can be said to be equal. In this embodiment, 14 holes 19 are provided.

Five fins 20 are provided on the inner peripheral surface of the central tube 16, connecting the central axis of the central tube 16 to the inner peripheral surface and dividing the space inside the central tube 16. The fins 20 are of the same shape and are spaced equally apart from each other. In other words, the fins 20 divide the space inside the central tube 16 into five equal parts.

The fin 20 is a plate of approximately uniform thickness, and is curved at a predetermined curvature in the circumferential direction. This curvature is constant from the front side to the back side of the fin 20. Because the diameter of the central tube portion 16 increases from the front side to the back side, the connection portions between the fin 20 and the inner peripheral surface of the central tube portion 16 each form a curve that bends in the same direction.

The attachment 10 described above is attached to the tip of the flexible duct 102 by inserting the tip of the flexible duct 102 between the outer circumferential tube portion 11 and the connecting tube portion 12. At this time, the camber 14 provided on the connecting tube portion 12 catches on the bellows of the flexible duct 102, preventing the flexible duct 102 from coming loose from the tip.

Next, a case where the attachment 10 is attached to the tip of the flexible duct 102 and air flows from the rear side of the attachment 10 to the front side will be described with reference to Figures 9 and 10. In Figures 9 and 10, the arrows indicate the direction of the airflow.

The airflow blown out from the blower 100 passes through the main duct 101 and the flexible duct 102 and reaches the rear side of the attachment 10. The airflow that reaches the rear side of the attachment 10 is guided by the inlet tube 16 toward the central axis of the attachment 10, and toward the opening 18b on the rear side of the central tube 18 and the rear side of the flange 17. At this time, the flow path area of the inlet tube 16 becomes smaller toward the front side, so the airflow that reaches the opening 18b on the rear side of the central tube 18 and the rear side of the flange 17 has a faster flow rate than the airflow passing through the flexible duct 102. The inlet tube 16 has the function of guiding the airflow toward the central axis of the attachment 10, and can therefore be called a guide section.

Part of the airflow that reaches the rear side of the flange portion 17 passes through the hole 19 and is blown out from the front side of the hole 19 as a second airflow. At this time, since the outer end 19b of the hole 19 is linearly connected to the inner circumferential surface of the inlet flow passage 16, the second airflow blows out while maintaining a state of heading in the central axis direction of the attachment 10. In addition, since the height of the hole 19 in the direction perpendicular to the central axis becomes smaller from the rear side to the front side, the second airflow blowing out from the hole 19 is faster than when it flows into the hole 19. In addition, since the outer end 19b of the hole 19 has the function of guiding the airflow toward the central axis direction of the attachment 10, it can be called a guide portion, similar to the inlet tube portion 16.

The second airflow blown out from the holes 19 is an airflow guided toward the central axis by the introduction tube portion 16 and the outer end portion 19b of the holes 19, so it flows along the outer periphery of the central tube portion 18 toward the periphery of the front opening 18a. As shown in FIG. 8, the second airflows blown out from adjacent holes 19 in the circumferential direction merge before reaching the front opening 18, forming an annular airflow that covers the entire circumference of the front opening 18a.

Meanwhile, the airflow that reaches the rear side of the flange portion 17 and does not pass through the holes 18 merges with the airflow that reaches the rear opening 18b of the central tube portion 18 and flows into the central tube portion 18. The central tube portion 18 has a gradually decreasing flow area, similar to the introduction tube portion 16, so the flow speed increases in inverse proportion to the flow area. In other words, the first airflow is blown out from the front opening 18a with a faster flow speed than the second airflow. In addition, the fins 20 provided inside the central tube portion 18 turn the airflow into a vortex that rotates around the central axis of the attachment 10, and blows out from the front opening 18a of the central tube portion 18.

In this way, the first airflow blown out from the front opening 18a is surrounded by the annular second airflow blown out from the hole 19. When airflows with different flow speeds come into contact, the airflow accelerates or decelerates at the boundary so that the relative speed between the airflows becomes zero. Therefore, although the first airflow slows down when it comes into contact with the second airflow, the second airflow also flows in the same direction as the first airflow, and therefore the deceleration caused by the first airflow coming into contact with the second airflow is smaller than the deceleration caused by the first airflow coming into contact with the outside air. This reduces the deceleration of the first airflow, allowing the airflow blown out from the front of the attachment to reach farther.

The effects of the attachment 10 according to the present embodiment described above will now be explained in relation to each component of the attachment 10.

- Since the holes 19 are provided at intervals in the flange portion 17, the ratio of the airflow passing through the holes 19 to the total airflow blown into the attachment 10 is reduced. Therefore, more airflow flows into the rear opening 18b of the central tube portion 18, and the flow rate of the first airflow blown out from the front opening 18a can be increased. On the other hand, if the holes 19 are provided at intervals from each other, gaps will be created between the second airflow, which is the airflow blown out from the holes 19. In this regard, since the flange portion 17 is provided around the rear opening 18b of the central tube portion 18, the second airflow will diffuse and reach the periphery of the front opening 18a of the central tube portion 18. As a result, when the first airflow blows out from the front opening 18a, the periphery of the first airflow is covered by the second airflow, and contact between the first airflow and the outside air can be further suppressed. Therefore, the flow rate of the first airflow can be secured while the deceleration of the first airflow can be suitably suppressed.

The second airflow blown out of the hole 19 diffuses and reaches the periphery of the front opening 18a of the central tube portion 18. In this case, if the second airflow diffuses excessively, there is a risk that the second airflow reaching the periphery of the front opening 18a may not be sufficiently secured. In this respect, the truncated cone-shaped introduction tube portion 16 guides the airflow flowing into the hole 19 toward the central axis, and the outer end portion 19b of the hole 19 is inclined toward the central axis, so that the diffusion of the second airflow can be suppressed. This ensures a sufficient flow rate of the second airflow when it merges with the first airflow, and can effectively suppress the deceleration of the first airflow caused by the first airflow coming into contact with the outside air.

- Because the rear opening 18b of the central tube portion 18 and the rear of the flange portion 17 are located on a common imaginary plane perpendicular to the central axis, airflow that reaches the rear side of the flange portion 17 and does not pass through the hole 19 is more likely to flow into the rear opening 18b of the central tube portion 18. This makes it possible to increase the flow rate of the first airflow.

- The central tube portion 18 is shaped like a truncated cone, which makes it possible to increase the speed of the first airflow blowing out from the front opening 18a of the central tube portion 18.

- Because the holes 19 are spaced apart around the circumference of the annular flange portion 17, the second airflow blowing out of the holes 19 tends to form an annular layer before it reaches the front opening of the central tube portion 18. This allows the second airflow to cover the entire circumference of the first airflow, and more effectively suppresses the deceleration of the first airflow caused by contact between the first airflow and the outside air.

- The inner end 19a of the hole 19 is shaped to follow the outer peripheral surface of the central tube portion 18, so the second airflow blowing out of the hole 19 flows around the front opening 18a along the outer peripheral surface of the central tube portion 18. This makes it more difficult for outside air to get between the first and second airflows when the second airflow reaches the front opening 18a, and makes it possible to more effectively suppress deceleration caused by contact between the first airflow and the outside air.

The second airflow blowing out from the holes 19 tends to diffuse outward toward the outer end 19b, so the layer of the second airflow between the outer ends 19b of two holes 19 that are close in the circumferential direction tends to become thin. In this regard, because the outer end 19b is an arc with a larger central angle than the inner end 19a, the flow rate of the second airflow blowing out from the outer end 19b side can be increased, and the thickness of the annular layer between the holes 19 can be ensured.

- The total length of the outer ends 19b of the holes 19 is greater than the outer circumference of the front opening 18a, so that when the second airflow blown out of the holes 19 reaches the front opening 18, even if it maintains the shape it had when it was blown out, the second airflow becomes an annular airflow that surrounds the entire circumference of the front opening 18a. This makes it possible to more effectively suppress the deceleration caused by contact between the first airflow and the outside air.

- If the total length of the outer ends 19b of the holes 19 is made larger than the outer circumference of the front opening 18a, the area of the holes 19 will be excessively large, and it will be impossible to ensure a sufficient amount of airflow flowing into the central tube portion 18. In this regard, because the area of the holes 19 and the area between the holes 19 are made equal, it is possible to ensure a sufficient amount of airflow flowing into the central tube portion 18.

- When the airflow is a vortex, the flow speed increases toward the center of the vortex and decreases toward the end of the vortex. In this case, the end of the vortex slows down as it comes into contact with the outside air, but the center of the vortex is protected by the vortex on the end side and deceleration is suppressed. In this embodiment, fins 20 are provided on the central tube portion 18, making it possible to make the first airflow a vortex, and the outer periphery of the vortex is covered by the second airflow, making it possible to better maintain the speed of the center of the first airflow, which is a vortex.

- When manufacturing resin molded products, etc., it is difficult to provide a member with a curvature that changes in the front-to-rear direction inside a cylindrical member. In this regard, the circumferential curvature of the fin 20 is constant from the front opening 18a side to the rear opening 18b side, so it can be easily manufactured even when the attachment 10 is made of resin, etc.

Second Embodiment
An attachment 110 according to this embodiment will be described with reference to Figures 11 to 13. The attachment according to this embodiment is attached to the tip of a flexible duct 102 when in use, similarly to the first embodiment.

In the attachment 110 of this embodiment, the outer circumferential tube portion 111, the connecting tube portion 112, the connecting portion 113, the notch 114, and the barb 115 are the same as those in the first embodiment, so their description will be omitted.

In the attachment 110 according to this embodiment, unlike the first embodiment, there is no introduction tube portion 16, and instead a ring-shaped flange portion 117 is provided on the inner circumference of the rear end of the outer circumferential tube portion 111. As in the first embodiment, this flange portion 117 is perpendicular to the central axis of the outer circumferential tube portion 111, and the center of the flange portion 117 coincides with the central axis of the outer circumferential tube portion 17.

The inner circumference of the flange portion 117 is provided with a central cylinder portion 118 in the shape of a truncated cone cylinder, the diameter of which decreases from the flange portion 117 toward the front side. This central cylinder portion 118 also shares a central axis with the outer peripheral cylinder portion 111, and the angle of the generatrix of the central cylinder portion 118 with respect to the central axis is 30 degrees. The front opening 118a, which is the opening on the front side of the central cylinder portion 118, is located on the same imaginary plane as the front of the connection portion 113. The length of the central cylinder portion 118 in the front-to-rear direction is approximately equal to that of the outer peripheral cylinder portion 111 in the front-to-rear direction. In addition, the thickness of the side surface of the central cylinder portion 118 is approximately uniform. The rear opening 118b, which is the opening on the rear side of the central cylinder portion 118, and the rear surface of the flange portion 117 are located on a common imaginary plane perpendicular to the central axis, and the rear opening 118b of the central cylinder portion 118 and the flange portion 117 share an opening.

As in the first embodiment, the flange portion 117 has a plurality of holes 119 that penetrate in the front-rear direction and are spaced apart from each other. The inner end 119a, which is the end on the central axis side of the hole 119, is an arc that follows the outer periphery of the rear opening 18b of the central flow passage 118 in a front view. Furthermore, the end 119a on the central axis side of the hole 119 is at a constant distance from the central axis in the front-rear direction. In other words, the end 119a on the central side of the hole 119 is an arc-shaped curved surface parallel to the central axis. In other words, the end 19a on the central side of the hole 119 is an arc-shaped curved surface parallel to the central axis.

The outer end 119b, which is the end on the outer periphery of the hole 119, shares a center line with the inner end 119a in a front view, and is an arc with a larger central angle than the inner end 119a. This outer end 119b is inclined toward the central axis from the rear end side to the front side. Therefore, the height in the direction perpendicular to the central axis of the hole 119 decreases from the rear side to the front side. In addition, a pair of side ends 19c, which are the ends in the circumferential direction of the hole 19, are each straight lines connecting the inner end 19a and the outer end 19b.

In the hole 119 thus configured, as in the first embodiment, the total arc length of the outer end 119b is greater than the outer circumference of the front opening 118a of the central tube portion 118. In addition, the arc length of the inner end 119a and the outer end 119b is set so that the area of the hole 119 in a front view is equal to the area sandwiched between a pair of holes 119 adjacent in the circumferential direction.

With the above configuration, the attachment 110 of this embodiment achieves effects similar to those of the first embodiment.

<Modification>
The structures of the attachments 10 and 110 are not limited to those shown in the embodiment, and may be modified as appropriate to have a common function. Examples of modified functions of the attachments according to the embodiment include the following.

- In the embodiment, the attachment 10, 110 is attached to the tip of the flexible duct 102, but the attachment target of the attachment 10, 110 is not limited to the flexible duct 102, but may be any gas outlet. In this case, the shapes of the outer circumferential tube portion 11, 111 and the connecting tube portion 12, 112 may be changed according to the attachment target. Also, the attachment 10, 110 may not be provided with the connecting tube portion 12, 112, and the outer circumferential surface of the outer circumferential tube portion 11, 111 may be attached to the inner circumferential surface of the gas outlet.

- In the embodiment, the shape of the central tube portion 18, 118 is a truncated cone tube, but the shape of the central tube portion 18, 118 may be a cylinder, a truncated pyramid tube, or a polygonal tube. Even in this case, the second airflow blown out from the hole diffuses around the central tube portion 18, 118 while heading toward the front periphery of the central tube portion 18, 118, so that an effect similar to that of the embodiment can be obtained. Similarly, the shape of the introduction tube portion 16 may be a cylinder, a truncated pyramid tube, or a polygonal tube.

- The shape of the holes 19, 119 is not limited to that shown in the embodiment. For example, the inner end 19a, 119a and the outer end 19b, 119b of the hole may be arc-shaped with equal central angles, or the central angle of the inner end 19a, 119a may be larger than the central angle of the outer end 19b, 119b. Furthermore, the shape of the holes 19, 119 may be semicircular, circular, etc.

- In each embodiment, a flange portion 17, 117 is provided and a hole 19, 119 is provided in the flange portion 17, 117, but the flange portion 17, 117 may not be provided and a hole may be provided in the side of the truncated cone-shaped central tube portion 18, 118. Even in this case, a part of the airflow flowing in from the back surface of the attachment 10, 110 passes through the hole and is blown out as a second airflow, and reaches the periphery of the front opening of the central tube portion 18, 118 along the outer surface of the central tube portion 18, 118. In addition, the airflow that does not pass through the hole is blown out as a first airflow from the front opening 18a, 118a of the central tube portion 18, 118, so that an effect equivalent to each embodiment is achieved.

- In the embodiment, the shape of the fins 20, 120 provided inside the central cylinder portion 18, 118 is not limited to that shown in the embodiment, and may be any shape that can generate a vortex that rotates the first airflow around the central axis of the central cylinder portion 18, 118. For example, the circumferential curvature of the fins 20, 120 may be gradually increased from the back side to the front side. Also, in the embodiment, the fins 20, 120 are connected on the central axis of the central cylinder portion 18, 118 and divide the interior of the central cylinder portion 18, 118 equally. However, the fins 20, 120 may not be connected on the central axis, and may protrude from the inner circumferential surface of the central cylinder portion 18, 118 to a range not reaching the central axis.

- In the embodiment, the attachment 10, 100 is connected to the tip of the flexible duct 102, but the gas outlet at the tip of the flexible duct or the like may be provided with a structure similar to the attachment 10, 100 of the embodiment. Specifically, the tip of the gas outlet may be similar to the outer circumferential tube portion, and an introduction tube portion, a flange portion, a central tube portion 18, etc. may be provided inside it.

- In the embodiment, the arc length of the inner end 19a and the outer end 19b of the hole 19 is determined so that the area of the hole 19 in a front view is equal to the area sandwiched between a pair of adjacent holes 19 in the circumferential direction, but this is not limited to the above. As long as the area of the hole 19 in a front view is similar to the area sandwiched between a pair of adjacent holes 19 in the circumferential direction, an effect equivalent to that of the embodiment can be obtained. Also, even if one area is about half the area of the other, a certain effect can be obtained in terms of suppressing the deceleration of the first airflow while ensuring the flow rate of the first airflow.

- In the embodiment, the inner diameter of the flexible duct 102 and the flow rate of the air flow passing through the flexible duct 102 are specified, but this is merely an example and can be applied to flexible ducts 102 of various sizes, and the flow rate of the air flow within the flexible duct 102 is not limited to the embodiment. In such a case, the size of the attachment 10, 100 may be selected to match the size of the flexible duct 102 to which it is to be attached.

- In the embodiment, the attachment 10, 100 is connected to the tip of the flexible duct 102, but the connection target of the attachment 10, 100 is not limited to this, and the attachment 10, 100 can also be attached to a cylindrical outlet other than the flexible duct 102. The attachment 10, 100 can also be attached to the airflow outlet of a wall surface, equipment, etc., in which case the attachment 10, 100 can be provided with an attachment structure corresponding to the airflow outlet to which it is to be attached.

10...attachment, 11...outer cylindrical portion, 16...introduction cylindrical portion, 17...flange portion, 18...central cylindrical portion, 18a...front opening, 18b...rear opening, 19...hole, 19a...inner end portion, 19b...outer end portion, 20...fin 110...attachment, 111...outer cylindrical portion, 117...flange portion, 118...central cylindrical portion, 118a...front opening, 118b...rear opening, 119...hole, 119a...inner end portion, 119b...outer end portion, 120...fin

Claims (5)

An attachment having a rear side attached to an airflow outlet and passing the airflow from the rear side to a front side,
a central cylinder portion having a front opening which is an opening on the front side and a rear opening which is an opening on the rear side, the central cylinder portion allowing the airflow to pass from the rear opening to the front opening;
a limiting portion provided around the entire periphery of the rear opening of the central tube portion and limiting the passage of the airflow;
a plurality of holes provided in the limiting portion, penetrating the limiting portion from the rear side to the front side, the holes being spaced apart from one another;
the rear opening of the central tube portion and the rear end of the restriction portion are located on a virtual plane perpendicular to the direction of travel of the airflow ,
An attachment , wherein a cylindrical guide portion having a diameter that decreases from the rear side to the front side is provided on the rear side of the restricting portion. An attachment having a rear side attached to a tip of a cylindrical duct having a bellows-shaped outer surface, and allowing an airflow blown out of the duct to pass from the rear side to a front side,
a central cylinder portion having a front opening which is an opening on the front side and a rear opening which is an opening on the rear side, the central cylinder portion allowing the airflow to pass from the rear opening to the front opening;
a limiting portion provided around the entire periphery of the rear opening of the central tube portion and limiting the passage of the airflow;
A plurality of holes are provided in the limiting portion, the holes penetrate the limiting portion from the rear side to the front side, and are provided at intervals from each other ;
A cylindrical outer circumferential cylinder portion provided on an outer circumferential side of the limiting portion;
a cylindrical connecting tube portion provided on an outer circumferential side of the outer circumferential tube portion;
a ridge provided on the connecting tube portion and curved toward the outer circumferential tube portion,
the rear opening of the central tube portion and the rear end of the restriction portion are located on a virtual plane perpendicular to the direction of travel of the airflow ,
The attachment is configured such that the tip of the duct is inserted between the outer circumferential tubular portion and the connecting tubular portion, and the barb is hooked onto the bellows of the duct. The limiting portion further includes a cylindrical outer circumferential cylindrical portion provided on an outer circumferential side of the limiting portion,
The attachment according to claim 1 , wherein an inner surface of the outer circumferential tube portion that is closer to the front side than the limiting portion is located outer circumferentially than the hole without overlapping with a front surface of the hole. the central cylinder portion has a truncated cone shape whose inner diameter decreases from the rear opening toward the front opening,
The attachment according to any one of claims 1 to 3, wherein the limiting portion is an annular plate that shares a central axis with the central tube portion. An airflow outlet structure comprising the attachment according to any one of claims 1 to 4 , which allows airflow to pass from a rear side to a front side.