JP5255490B2 - Fan casing - Google Patents

Description

  The present invention provides a casing main body that houses a rotationally driven impeller, a front wall having a suction port for sucking gas along the direction of the rotational axis of the impeller, a rear wall disposed opposite to the front wall, A flow channel is formed between the front wall and the rear wall and the outer periphery of the impeller accommodated therein to flow gas toward a blowout opening that opens in a part of the impeller in the rotational direction. A circumferential inner wall, and the circumferential inner wall has a tongue portion having a minimum distance from the outer periphery of the impeller, and a blowout flow path to the blowout port that is continuous with the flow flow path. The present invention relates to a fan casing in which a continuous portion continuous with a flow path wall is a circulation end, and the flow path width of the flow channel is sequentially increased from the circulation start end to the circulation end.

  The fan including the fan casing as described above sucks gas (for example, air) from the suction port along the rotational axis direction of the impeller, and the sucked gas is centrifugally directed from the inside of the impeller toward the outer periphery. It is configured as a centrifugal fan that causes the discharged air to flow out from the air outlet.

In the casing body, gas is sucked in from the suction port along the rotational axis of the impeller, but when the static pressure is high, the pressure in the flow channel increases, and the gas flows from the gap between the impeller and the front wall to the suction port side. May leak out and the gas may flow back to the outside through the suction port.
Therefore, in the conventional fan casing, a convex portion protruding inward from the inner wall of the front wall is provided between the suction port and the inner circumferential wall, and this convex portion is the entire circumference of the circular suction port. (See, for example, Patent Document 1). In the fan casing described in Patent Document 1, even if the pressure in the flow channel increases, the gas flow to the suction port side can be blocked by the convex portion, and the gas flows back to the outside through the suction port. Can be prevented.

JP 2004-68644 A

  In the fan casing described in Patent Document 1, since the convex portion is arranged over the entire circumference of the circular suction port, the air flowing between the suction port and the convex portion is impellered by the convex portion. It is inhibited from flowing outward in the radial direction of the vehicle. Thereby, the air flowing between the suction port and the convex portion continues to flow around the entire circumference of the circular suction port and is not easily guided toward the blowout port. Therefore, the flow rate of air that can be guided to the air outlet is reduced with respect to the flow rate of air sucked from the air inlet, and the power consumption of the motor increases when the target flow rate gas is blown out from the air outlet.

  The present invention has been made in view of the above-described problems, and a purpose of the present invention is to effectively guide air sucked from the suction port to the blow-out port while preventing a backflow of gas to the suction port. It is in providing a casing for use.

In order to achieve this object, the fan casing according to the present invention is characterized in that the casing body that houses the rotationally driven impeller has a suction port for sucking gas along the rotational axis direction of the impeller. An opening is provided in a part in the rotational direction of the impeller between a front wall, a rear wall disposed opposite to the front wall, and an outer periphery of the impeller accommodated by connecting the front wall and the rear wall. A circulating inner wall for forming a flow channel for allowing gas to flow toward the outlet, and the circulating inner wall has a tongue portion having a minimum distance from the outer periphery of the impeller as a circumferential start end and the flow channel. The continuous portion that continues to the blowout flow path wall that forms the blowout flow path to the blowout outlet is the circulation end, and the flow passage width of the flow channel is sequentially increased from the turn start end to the turn end. In the fan casing,
A convex portion projects inward from the inner wall of the front wall between the suction port and the circumferential inner wall, and the convex portion passes through the tongue portion in the rotational direction of the impeller, and the suction port is circular. than tangent of the mouth and projected starting the downstream side in the rotation direction of the impeller, and the gas flowing between said inlet and said convex portion is allowed to flow toward the outlet acceptable With the position as a projecting end, it extends in the rotational direction of the impeller from the projecting start end to the projecting end ,
The protruding start end of the convex portion is provided at a position downstream of the tongue portion in the rotational direction of the impeller .

According to the above characteristic configuration, even if the pressure in the flow channel increases, the gas flow to the suction port side can be blocked by the convex portion provided between the suction port and the inner circumferential wall. The convex portion extends from the projecting start end to the projecting end, and is not provided over the entire circumference of the suction port. The convex portion by the projecting starting the downstream side in the rotation direction of the impeller than the tangent line of the circular inlet through the tongue, in the vicinity of tongue pressure of the flow passage is increased , It is possible to eliminate the convex portion. Thereby, it can prevent that the pressure in a flow path becomes still higher by the presence of a convex part, and it becomes easy to produce the backflow to a suction inlet. Moreover, since the convex part has the allowable position which allows the gas flowing between the suction port and the convex part to flow toward the blower outlet, it flows between the suction port and the convex part. The flow of the gas toward the outlet is not hindered by the convex portion, and the gas can be appropriately flowed toward the outlet.
As described above, while preventing the backflow of gas to the suction port, the air sucked from the suction port can be effectively guided to the outlet, and the power consumption of the motor is reduced when the target flow rate of gas is blown from the outlet. A fan casing capable of achieving the above can be realized.
Furthermore, since the protrusion start end of the convex portion is provided at a position downstream of the tongue in the rotational direction of the impeller, air can be more effectively guided to the outlet.

The fan casing according to the present invention is further characterized in that the protruding start end of the convex portion is downstream of the tangent in the rotational direction of the impeller, and the end of rotation of the inner wall of the rotation and the suction port Of the angles formed by the straight line connecting the center and the straight line connecting the protruding start end of the convex portion and the center of the suction port, the angle formed by the two straight lines on the side including the outlet is between the two straight lines. It is in the point arrange | positioned in the position which will be within 90 degree | times.

  According to the above characteristic configuration, it is possible to eliminate the convex portion over the entire vicinity of the tongue portion where the pressure in the flow channel increases. Therefore, the pressure in the flow channel is further increased due to the presence of the convex portion, and it is possible to accurately prevent the backflow to the suction port. In addition, there is a flow in which the gas flows toward the air outlet between the suction port and the convex portion, and the pressure at the protruding start end can be made lower than the pressure near the tongue, and this pressure difference causes the tongue to Since the gas in the vicinity of the portion can flow between the suction port and the convex portion, the backflow to the suction port in the vicinity of the tongue can be prevented from this point. By preventing the backflow to the suction port in this way, it is possible to accurately prevent the generation of noise caused by a collision with the outer periphery of the impeller when backflowing to the suction port.

  A further characteristic configuration of the fan casing according to the present invention is that the projecting end of the convex portion is disposed with the circumferential end of the circumferential inner wall as the allowable position.

  According to the above characteristic configuration, the circulation end of the circulation inner wall is the termination of the flow channel. Therefore, the pressure in the flow channel is increased by setting the projecting termination of the convex portion as the circulation termination of the circulation inner wall. While effectively preventing the backflow to the suction port at the convex portion, it is possible to eliminate the convex portion in the outlet flow path. Thereby, the gas which flows between the suction port and the convex portion can be guided to the blowout flow path and can be accurately flowed toward the blowout port while effectively preventing the backflow to the suction port.

  A further characteristic configuration of the fan casing according to the present invention is that the distance between the suction port and the convex portion is configured such that the protruding end side of the convex portion is larger than the protruding start end side. is there.

According to the above characteristic configuration, in the flow path between the suction port and the convex portion, the pressure at the projecting end side is lower than the projecting start end side. The gas in between can be made to flow accurately toward the outlet.
The fan casing according to the present invention is
In the casing body, the gas sucked through the intake opening that opens in a part of the rotation direction of the impeller on the outside of the front wall circulates in the same direction as the rotation direction of the impeller to the suction port. A circulation channel that flows toward the end, and an introduction unit that is disposed at a terminal portion of the circulation channel and introduces the gas that has flowed in the circulation channel to the suction port,
The circumferential flow path is formed between the circumferential flow path walls erected on the front side from the front wall, and the side away from the front wall in the rotational axis direction of the impeller is opened,
Suitably adopting a configuration in which the introduction portion applies a force along the rotational axis direction of the impeller to the gas that has reached the suction port along the circulation channel and introduces the gas into the suction port. Is possible.

Perspective view of the casing body as seen from the front side Perspective view of the casing body viewed from the rear side Sectional view of the casing body taken longitudinally along the rotational axis direction of the impeller The figure which shows the casing body seen from the front side The figure which shows the casing body seen from the back side in the state where the back wall was removed The figure which shows the casing main body seen from the back side in the state which removed the rear wall and the impeller Side view of the casing body viewed from the direction in which the air outlet opens Perspective view of the casing body as seen from the front side Perspective view of the casing body viewed from the rear side The figure which shows the casing main body seen from the back side in the state which removed the rear wall and the impeller The figure which shows the casing main body seen from the back side in the state which removed the rear wall and the impeller

An embodiment of a fan provided with a fan casing according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 6, the fan 1 includes an impeller 2 that is rotationally driven by a motor (not shown), and a casing body that accommodates the impeller 2 by forming a suction port 3 and an outlet 4. 5. The suction port 3 opens along the rotational axis direction X of the impeller 2 (hereinafter simply referred to as “rotational axis direction X”), and the blowout port 4 rotates in the rotational direction Y of the impeller 2 (hereinafter referred to as “rotational axis direction X”). , Simply abbreviated as rotation direction Y). The impeller 2 is provided with a plurality of blades 2a arranged side by side on the periphery, and is a suction plate having one end opened in the rotational axis direction X and a bottom plate closed at the other end. The impeller 2 is housed in the housing space in such a manner that the suction portion faces the front wall 8 of the casing body 5 and the bottom plate faces the rear wall 13 of the casing body 5. Thereby, the air sucked from the suction port 3 is taken into the impeller 2 through the suction portion of the impeller 2, and the air inside the impeller 2 is centrifugally driven by the blades 2a by the rotational drive and the bottom plate of the impeller 2. It is configured to be leaked.

  The fan 1 sucks air (gas) from the suction port 3 along the rotational axis direction X, and causes the sucked air to flow out in the centrifugal direction from the inside of the impeller 2 to the outer periphery. The centrifugal fan is blown out from the outlet 4. For example, such a fan 1 is used as a fan for a ventilation fan.

  The fan casing according to the present invention is configured by a casing body 5 formed in a rectangular parallelepiped, and the casing body 5 includes an intake side forming portion 6 that forms an intake structure for sucking air at the suction port 3. A blow-out side forming portion 7 that forms a blow-out structure for blowing out air sucked in from the blow-out opening 3 from the blow-out opening 4 is provided. In the casing body 5, the suction side forming portion 6 is formed in front of the front wall 8 (left side in FIGS. 1 to 3) with respect to the front wall 8 in which the air inlet 4 is formed in the rotation axis direction X. The blowing side forming portion 7 is formed on the rear side (right side in FIGS. 1 to 3) of the front wall 8.

  FIG. 1 mainly shows the suction side forming part 6, shows an exploded perspective view of the casing body 5 as seen from the front side of the suction port 3, and FIG. 2 mainly shows the outlet side forming part 7. The exploded perspective view of casing body 5 seen from the back side of inlet 3 is shown. FIG. 3 shows a cross-sectional view of the casing body 5 as viewed from the side when the casing body 5 is longitudinally cut along the rotational axis direction X. 4 is a view showing the casing body 5 as seen from the front side of the suction port 3, and FIG. 5 is a view showing the casing body 5 as seen from the rear side of the suction port 3 with the rear wall 13 removed. FIG. 6 is a view showing the casing body 5 as seen from the rear side of the suction port 3 with the rear wall 13 and the impeller 2 removed.

(Suction side forming part)
The suction side forming part 6 is integrally formed on the outer side (front side) from the outer wall of the front wall 8. The suction side forming portion 6 is caused to flow in the suction passage 9 for sucking air, the circulation passage 10 for flowing the air sucked in the suction opening 9 toward the suction port 3, and the circulation passage 10. And an introduction portion 11 for introducing the air into the suction port 3.

The intake opening 9 opens to a part of the rotation direction Y (the left side in FIG. 4) outside the front wall 8, and is disposed outside the suction port 3 in the radial direction of the impeller 2.
The circulation channel 10 is formed in a spiral shape that circulates the air taken in through the intake opening 9 in the same direction as the rotation direction Y and flows toward the suction port 3. And the circulation channel | path 10 becomes a shape which approaches the suction inlet 3 fundamentally, and the flow path width is comprised narrowly, so that the side which approaches the suction inlet 3 is approached. The circumferential flow path 10 is formed between the circumferential flow path walls 12 erected on the outer side (front side) from the front wall 8, and the side away from the front wall 8 in the rotational axis direction X is open. Thereby, air can be sucked along the rotational axis direction X even in the middle of the circulation flow path 10, and a larger amount of air can be flowed to the suction port 3.

  The introduction part 11 is disposed at the terminal part of the circulation channel 10 and introduces the air that has flowed in the circulation channel 10 into the suction port 3. The introduction portion 11 is continuous from the opening end portion of the suction port 3 continuously to the circumferential flow channel wall 12 positioned on the radially outer side of the suction port 3 among the pair of circumferential flow channel walls 12 forming the circumferential flow channel 10. It is formed in the shape of a wall extending on the side, and its tip extends to the vicinity of the center of the suction port 3. The introduction part 11 is formed in a curved shape along the rotation direction Y from the distal end side toward the proximal end side. As a result, the introduction part 11 applies a force along the rotational axis direction X to the air that has flowed in the circulation channel 10 to positively introduce the air into the circulation channel 10. The air thus flowed is introduced into the suction port 3.

  Thus, by providing the intake opening 9, the circulation channel 10, and the introduction unit 11, the air sucked through the intake opening 9 flows along the circulation channel 10, and the flow velocity of the air in the rotation direction Y Can be made to flow to the suction port 3. And since the air which flowed in the circulation channel 10 is given the force along the rotation axis direction X by the introduction part 11 and is actively flowed to the suction port 3 side, the air in the suction port 3 While increasing the amount of suction, air with an increased flow rate can be pushed into the suction port 3. Thereby, when blowing out the flow volume of the same air from the blower outlet 4, even if it does not set the rotational speed of the impeller 2 to a high rotational speed, the force which pushes more air into the suction inlet 3 can be inhaled, The power consumption of the motor can be reduced. As a result, for example, the fan 1 that can achieve a high static pressure (for example, 200 to 300 Pa) and a high flow rate (for example, 100 m <3> / h) can be configured.

[Blow-off side forming part]
The blow-out side forming portion 7 is connected between the rear wall 13 opposed to the front wall 8 and the outer periphery of the impeller 2 housed in the casing body 5 by connecting the front wall 8 and the rear wall 13. And a circulating inner wall 15 for forming a flow passage 14 for allowing air to flow toward the bottom.
The rear wall 13 is formed separately from the front wall 8 in a plate shape, and an accommodation space for accommodating the impeller 2 between the front wall 8 and the rear wall 13 is formed. The impeller 2 accommodated in the accommodating space has the rotation axis of the impeller 2 and the center of the suction port 3 aligned with each other, and is separated from the bell mouth portion 19 of the suction port 3 by a set distance (for example, 2 mm). Has been placed.
The circling inner wall 15 is composed of a straight standing wall integrally formed on the inner side (rear side) of the front wall 8 and surrounds the outer periphery of the impeller 2 accommodated in the accommodating space. A flow channel 14 is formed between the outer periphery. As shown in FIG. 5, the inner circumferential wall 15 is formed in a shape that draws an enlarged curve (for example, an involute curve) that sequentially increases the flow path width of the flow channel 14 from the circulation start end S <b> 1 toward the circulation end S <b> 2. Then, the circulating inner wall 15 forms the blowing passage 17 to the outlet 4 continuously from the flow passage 14 with the tongue portion 16 having the smallest distance from the outer periphery of the impeller 2 as the starting end S1. A continuous portion R continuing to the blowout flow path wall 18 is defined as a circulation end S2.

(Convex)
Next, the structure of the convex part 20 which is the characteristic structure of this embodiment is demonstrated based on FIG.3 and FIG.6. In this fan 1, the inner wall of the front wall 8 is formed in a flat shape. However, as shown in FIGS. 3 and 6, the inner wall of the front wall 8 is interposed between the suction port 3 and the rotating inner wall 15 (see FIG. On the right side in FIG.
The convex portion 20 extends in the rotation direction Y from the protrusion start end T1 to the protrusion end T2, and is not disposed over the entire circumference of the rotation direction Y, and a part of the rotation direction Y is opened. . And the convex part 20 makes the downstream side of the rotation direction Y the protrusion start end T1 rather than the tangent L1 of the circular shaped suction inlet 3 which passes the tongue part 16 toward the rotation direction Y, and the suction inlet 3 and the convex part 20 A permissible position that allows the air flowing between the two to flow toward the air outlet 4 is defined as a projecting end T2. The protrusion start end T1 of the protrusion 20 is downstream of the tangent L1 in the rotation direction Y, and a straight line L2 connecting the rotation end S2 of the rotation inner wall 15 and the center P of the suction port 3 and the protrusion start end T1 of the protrusion 20. And an angle α formed by a straight line L3 connecting the center P of the suction port 3 is disposed at a position where the angle α is not less than 0 degrees and not more than 90 degrees. The protruding end T2 of the convex portion 20 is disposed with the circumferential end S2 of the circumferential inner wall 15 as an allowable position. Moreover, the convex part 20 is formed in the shape which draws the expansion curve (for example, involute curve) located in the radial direction outer side of the impeller 2 toward the protrusion termination | terminus T2 from the protrusion start end T1. Thereby, the distance (distance in the radial direction of the impeller 2) between the suction port 3 and the convex portion 20 is configured such that the protruding end T2 side of the convex portion 20 is larger than the protruding start end T1 side. .

  By providing such a convex portion 20, air flowing between the suction port 3 and the convex portion 20 is blown out while preventing a back flow to the suction port 3 even when the pressure of the flow passage 14 increases. The flow can be positively made to flow in the flow path 17, and the air can be made to flow toward the outlet 4 through the blow-out flow path 17. Moreover, since the convex portion 20 does not exist in the tongue portion 16 and the region adjacent to the upstream side in the rotational direction Y from the tongue portion 16, the presence of the convex portion 20 prevents further increase in the pressure of the flow passage 14. Thus, it is possible to prevent the backflow to the suction port 3 from being easily generated. Further, the distance between the suction port 3 and the convex portion 20 (the distance in the radial direction of the impeller 2) is larger on the protruding end T2 side of the convex portion 20 than on the protruding start end T1 side. The pressure difference is utilized not only for the air flowing between the protrusion 20 and the convex portion 20, but also for the tongue 16 adjacent to the protrusion start end T1 and the air that has flowed out to the region adjacent to the upstream side in the rotational direction Y. Thus, it is possible to positively flow through the space between the suction port 3 and the convex portion 20 toward the protruding end T2 of the convex portion 20. Therefore, the air flowing between the suction port 3 and the convex portion 20 is effectively prevented while preventing the backflow to the suction port 3 in the region adjacent to the tongue portion 16 and the upstream side in the rotational direction Y. It can be made to flow toward the blower outlet 4.

(Blowout channel)
In this fan 1, as shown in FIG. 5, the blowout flow path 17 is formed continuously with the flow flow path 14, and is formed in a straight line shape from the end portion of the flow flow path 14 toward the blowout outlet 4. Yes. The blowout flow path 17 is continuously connected between the outer periphery of the impeller 2 and the blowout flow path wall 18, and is connected to the connection wall 21 and the blowout flow path wall 18 connected from the tongue 16 toward the blowout port 4. Is formed between.

  As shown in FIG. 7, the blowout flow path wall 18 is formed continuously with the circulating inner wall 15, and is configured by a straight standing wall like the rotating inner wall 15. On the other hand, the facing portion 16a facing the blowout flow path wall 18 in the tongue portion 16 is closer to the front wall 8 on the side away from the front wall 8 in the rotational axis direction X (lower side in FIG. 6). It is formed in an inclined shape that is farther from the outlet flow path wall 18 than the side. FIG. 7 shows a side surface portion of the casing body 5 when the inner side of the casing body 5 is viewed from the direction in which the air outlet 4 opens. As a result, the flow path portion where the tongue portion 16 and the blow flow path wall 18 face each other in the blow flow path 17 is closer to the front wall 8 on the side away from the front wall 8 in the rotational axis direction X. Also, the channel width is large. Further, as shown in FIGS. 5 and 6, the connecting wall 21 is formed in an inclined shape in which the distance from the blowing channel wall 18 increases toward the side closer to the blowing port 4.

  By providing such a blowout flow path 17, even if a large amount of air flows on the side away from the side approaching the front wall 8 in the rotation axis direction X, the blowout flow path according to the flow rate difference of the air The flow path width can be 17 and air can be flowed while reducing the pressure loss. Moreover, as described above, since a large amount of air can be sucked from the suction port 3 by the circulation channel 10 and the introduction portion 11, a larger amount of air is provided on the side away from the side approaching the front wall 8 in the rotational axis direction X. However, even a larger amount of air can smoothly flow through the blowout flow path 17 and be led to the blowout port 4. And since the distance between the connection wall 21 and the blowing flow path wall 18 is so large that it approaches the blower outlet 4, the air which flows through the blower flow path 17 can be actively guide | induced to the blower outlet 4. FIG. it can. Further, since the tongue portion 16 is formed in an inclined shape, the time until the air that has flowed out to the outer periphery of the impeller 2 hits the tongue portion 16 is gradually increased from the side approaching the front wall 8 to the side away from it. Therefore, a phase difference is generated in the sound generated when air hits the tongue portion 16, and the sounds generated by each other interfere with each other, thereby suppressing the generation of noise.

〔the flow of air〕
As shown by the arrows in FIG. 1 and FIG. 8, the air taken in through the intake opening 9 is swirled in the circulation channel 10 to reach the introduction part 11, and the introduction part 11 sucks the suction port 3. To be introduced. As shown by the arrows in FIGS. 2 and 9, the air introduced into the suction port 3 flows in the flow channel 14 along the rotation direction Y and flows toward the outlet 4 through the outlet channel 17. And blown out from the outlet 4.
Here, since air is blown out from the blower outlet 4 through the blowout flow path 17, more air is supplied from the suction port 3 in the vicinity of the region adjacent to the upstream side in the rotational direction Y with respect to the location of the blowout flow path 17. Will be sucked. Therefore, the introduction portion 11 is disposed in the vicinity of the region adjacent to the upstream side in the rotation direction Y with respect to the location where the blowout flow path 17 is disposed, and is disposed in a region where a large amount of air is sucked from the suction port 3. Has been. For example, as shown in FIG. 10, the introduction portion 11 includes a straight line L4 connecting the tongue portion 16 and the center P of the suction port 3 and the arrangement position of the introduction portion 11 (the center position of the introduction portion 11 in the rotation direction Y). An angle β formed by a straight line L5 connecting the center P of the suction port 3 is disposed at a position where the angle β is not less than 0 degrees and not more than 90 degrees.

(Partition section)
As described above, air flows through the circulation channel 10 outside the front wall 8, and air flows due to the rotational drive of the impeller 2 inside the front wall 8. Therefore, as shown in FIGS. 4 and 6, a partition 22 is provided in the suction port 3 to partition the air flow inside the front wall 8 and the air flow outside the front wall 8. The partition part 22 is configured in a plate shape extending inward from the opening end of the suction port 3. And the partition part 22 is arrange | positioned on the opposite side of the introducing | transducing part 11 and the rotation direction Y. FIG. As a result, the outside and the inside of the front wall 8 are communicated with each other through the suction port 3, but the suction port 3 is connected to the front wall by the partition portion 22 at a place away from the place where the introduction part 11 is disposed in the rotation direction Y. 8 and the inside of the front wall 8 can be divided. Therefore, the partition part 22 can prevent the air flowing in the circulation channel 10 from being short-circuited in the middle and being sucked from the suction port 3. On the contrary, it is possible to prevent the air inside the front wall 8 from flowing back to the outside of the front wall 8 through the suction port 3 by the partition portion 22. Thereby, the flow of air in the rotational direction Y by the circulation channel 10 outside the front wall 8 and the flow of air in the rotational direction Y by the rotational drive of the impeller 2 inside the front wall 8 interfere with each other. Can be suppressed by the partition portion 22. Therefore, a larger amount of air can be sucked in at the suction port 3, and the air sucked in at the suction port 3 can be efficiently flowed to the flow channel 14 by the rotational drive of the impeller 2. Air can be flowed toward the outlet 4.

As shown in FIG. 11, on the side facing the inner side of the front wall 8 of the partition portion 22, the first negative pressure region 23 is located on the downstream side in the air flow direction toward the air outlet 4 (on the downstream side in the rotational direction Y). The first negative pressure region forming part 24 is formed. For example, on the upstream side in the air flow direction toward the outlet 4 with respect to the partition portion 22 when air collides with the partition portion 22 (a region adjacent to the downstream side in the rotational direction Y with respect to the partition portion 22). A vortex flow W1 may occur. Since the first negative pressure region 23 is formed in the first negative pressure region forming part 24, air can be actively flowed into the first negative pressure region 23 using the negative pressure. Thereby, generation | occurrence | production of the vortex | eddy_current W1 can be suppressed and it can prevent that air stops flowing smoothly by the vortex | eddy_current W1.
Moreover, the partition part 22 is formed in the shape extended from the arrangement | positioning location of the 1st negative pressure area | region formation part 24 to the downstream of the flow direction of the air which goes to the blower outlet 4 (downstream side of the rotation direction Y). As a result, the air that has flowed to the first negative pressure region 23 flows toward the outlet 4 while being guided by the partition portion 22, and the air can smoothly flow toward the outlet 4. it can.

[Second negative pressure region forming section]
As shown in FIG. 11, on the side facing the inner side of the front wall 8 of the introduction portion 11, the second negative pressure region 25 is located downstream in the flow direction of air toward the blowout port 4 (downstream in the rotational direction Y). The second negative pressure region forming part 26 is formed. Similarly to the first negative pressure region forming unit 24 described above, the second negative pressure region forming unit 26 is also downstream of the air flow direction toward the outlet 4 with respect to the introducing unit 11 (rotates with respect to the introducing unit 11). Even if there is a possibility that the vortex W2 is generated in the region adjacent to the downstream side in the direction Y), the air is positively caused to flow into the second negative pressure region 25 by using the negative pressure. Generation | occurrence | production is suppressed and it is prevented that air stops flowing smoothly with the eddy current W2.

[Another embodiment]
Below, another embodiment which concerns on the structure of the convex part of the casing for fans of this invention is described.
(A) In the above-described embodiment, the convex portion 20 protrudes to the inside of the casing body 5 at the end. For example, the tip of the convex portion 20 is radially outward in the cross-sectional view shown in FIG. It can be made into the shape which protrudes to the 15 side.
Thereby, it is possible to more appropriately suppress the air repelled radially inward by the circulating inner wall 15 from returning to the suction port 3 beyond the convex portion 20.

(B) In the said embodiment, although the convex part 20 shall be arrange | positioned in the involute shape in the side view in which the convex part 20 shown in FIG. 6 is provided, it is also possible to make shapes other than an involute shape separately. Good. For example, in the circumferential direction of the circumferential inner wall 15 (the Y direction in FIG. 6), the bell mouth portion 19 of the suction port 3 is surrounded and the vicinity of the portion facing the air outlet 4 is open. be able to.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used as a fan casing that can effectively guide the air sucked from the suction port to the blowout port while preventing the backflow of gas to the suction port.

DESCRIPTION OF SYMBOLS 1 Fan 2 Impeller 3 Suction inlet 4 Outlet 5 Casing main body 8 Front wall 10 Circulation flow path 12 Circulation flow path wall 13 Rear wall 14 Flow flow path 15 Circulation inner wall 16 Tongue part 17 Outflow flow path 18 Outflow flow path wall 20 Convex Part P Suction port center S1 Circumference start end S2 Circumference end T1 Projection start end T2 Projection end R Continuous portion L1 Tangent line L2 of the suction port passing through the tongue portion in the rotational direction of the impeller Straight line L3 connecting the protrusion start end of the convex portion and the center of the suction port X The direction of the rotational axis of the impeller Y The direction of rotation of the impeller

Claims (5)

A casing body that accommodates a rotationally driven impeller includes a front wall having a suction port for sucking gas along the direction of the rotational axis of the impeller, a rear wall disposed opposite to the front wall, and the front wall, A circulating inner wall that forms a flow channel that allows gas to flow toward a blowout opening that opens in a part of the rotation direction of the impeller between the rear wall and the outer periphery of the impeller accommodated. Prepared,
The inner circumferential wall is continuous with a blowout channel wall that forms a blowout channel to the blower outlet, with a tongue portion having a minimum distance from the outer periphery of the impeller as a circumferential start end. A fan casing in which a continuous portion is a circulation end, and the flow passage width of the flow channel is sequentially increased from the circulation start end toward the circulation end,
A convex portion is projected inward from the inner wall of the front wall between the suction port and the inner circumferential wall,
The convex portion, rather than tangent of the circular said inlet through said tongue portion toward the rotation direction of the impeller and protrude starting the downstream side in the rotation direction of the impeller, and, with the inlet With the allowable position allowing the gas flowing between the protrusions to flow toward the blowout port as a protruding end, it extends in the rotational direction of the impeller from the protruding start end to the protruding end,
A fan casing in which a protruding start end of the convex portion is provided at a position downstream of the tongue in the rotational direction of the impeller . The projecting start end of the convex part is downstream of the tangent in the rotational direction of the impeller, and a straight line connecting the circulation end of the circumferential inner wall and the center of the suction port, the projecting start end of the convex part, and the The angle formed by the straight line connecting the center of the suction port and the straight line on the side including the outlet between the straight lines is disposed at a position where the angle is within 90 degrees. The fan casing as described in 1.   3. The fan casing according to claim 1, wherein the protruding end of the convex portion is disposed with the rotation end of the inner wall as the allowable position.   The fan casing according to any one of claims 1 to 3, wherein a distance between the suction port and the convex portion is configured such that a protruding end side of the convex portion is larger than a protruding start end side. .   In the casing body, the gas sucked through the intake opening that opens in a part of the rotation direction of the impeller on the outside of the front wall circulates in the same direction as the rotation direction of the impeller to the suction port. A circulation channel that flows toward the end, and an introduction unit that is disposed at a terminal portion of the circulation channel and introduces the gas that has flowed in the circulation channel to the suction port,
  The circumferential flow path is formed between the circumferential flow path walls erected on the front side from the front wall, and the side away from the front wall in the rotational axis direction of the impeller is opened,
  The said introduction part gives the force which follows the rotation axial center direction of the said impeller to the gas which reached the said suction inlet along the said circumference flow path, and introduces the said gas to the said suction inlet. The fan casing according to any one of the preceding claims.

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