JP2010236371A - Axial blower, air conditioner and ventilator - Google Patents

Abstract

An axial blower that improves noise and efficiency by reducing a jet airflow generated in a gap between an outer peripheral edge of a blade and a bell mouth, and an air conditioner and a ventilation fan using the axial blower.
The axial blower of the present invention is provided with a bell mouth 5 on the outer periphery of an impeller 4 composed of a plurality of blades 13 of a forward wing type. The bell mouth 5 has a throttle part 52 formed facing the outer periphery of the impeller 4 so as to partition the suction area and the blowout area of the blower, and a suction side opening part 51 that widens the suction side of the throttle part 52. And a blowing side opening 53 that expands the blowing side. The diaphragm 52 is necessary between the first diaphragm 52 a that forms the minimum gap n between the outer peripheral edge R of the blade 13 and the outer peripheral edge R of the blade 13. The second throttle part 52b forms a gap having a dimension larger than the minimum dimension n, and the second throttle part 52b is formed on the outlet side of the first throttle part 52a.
[Selection] Figure 2

Description

  The present invention relates to the structure of an axial blower (propeller fan).

  An axial blower is generally used as an outdoor unit for an air conditioner or a blower for a ventilation fan. Here, the typical structural example of the outdoor unit for air conditioners which employ | adopted the general axial flow fan as an air blower is shown in FIGS.

  As shown in these drawings, a general outdoor unit for an air conditioner has a heat exchanger 2 disposed in a main body casing 1 having air suction ports 1 a and 1 b, and the air flow downstream side of the heat exchanger 2. The blower 3 is disposed at the air outlet (in this conventional example, the front air outlet). This air blower 3 is comprised from the axial-flow fan which consists of the impeller 4 and the bellmouth 5, and the fan guard 6 located in the blowing side (front side) of an axial-flow fan.

  Further, as shown in FIG. 9, the main body casing 1 is divided into left and right by a partition plate 7, and a side having a large space is a heat exchange chamber 8, and a side having a small space is a machine chamber 9. Air suction ports 1 a and 1 b are formed on the back and side surfaces of the main casing 1 that forms the back and side surfaces of the heat exchange chamber 8. The heat exchanger 2 is formed in an L shape and is disposed in the heat exchange chamber 8 so as to face the air suction ports 1a and 1b. On the other hand, the machine room 9 is provided with a compressor 11 and other components.

  The impeller 4 constituting the axial blower is formed integrally with the hub 14 so that the plurality of blades 13 are supported on the outer periphery of the hub 14 as can be seen from the impeller plan view of FIG. The blades 13 are formed in a forward wing shape in which the position of the outer peripheral edge is positioned forward in the rotational direction F with respect to the position of the hub-side base end S (that is, the inner peripheral edge) at the front edge 13a and the rear edge 13b. Has been. The hub 14 forms a rotation center of the impeller 4 and is connected and fixed to a drive shaft 12a of a fan motor 12 that rotationally drives the impeller 4. The fan motor 12 is supported and fixed to a fan motor mounting bracket (not shown) provided on the downstream side of the heat exchanger 2.

  The bell mouth 5 is formed on the outer periphery of the impeller 4 so as to partition the suction region X and the blowout region Y of the impeller 4. The bell mouth 5 and the fan guard 6 are attached to the front plate of the main casing 1.

The general outdoor unit for an air conditioner equipped with the axial blower configured as described above has the following problems.
That is, when the impeller 4 having a blade structure as shown in FIG. 10 rotates, an air flow α that flows from the high pressure surface 13d side to the low pressure surface 13e side on the outer peripheral edge R side of the blade 13 is generated. The airflow α forms a blade tip vortex β as shown in FIGS. 11 and 12. As shown in FIGS. 12 and 13, the turbulence of the discharge air flow caused by the blade tip vortex β is laminated and gradually grows as it goes to the downstream side. It interferes with the pressure surface 13d of the blade 13, the inner peripheral surface of the bell mouth 5, or the fan guard 6 that is a downstream structure of the axial fan. This further increases noise. Further, the blade tip vortex β away from the suction surface 13e of the blade 13 is further disturbed by the interference with the adjacent blade 13 as described above, and is emitted to the downstream side. Will do.

  Such a phenomenon becomes particularly remarkable when the chord length of the blade 13 is shortened in order to reduce the weight of the impeller 4 and reduce the cost. That is, when the chord length is shortened, as shown in FIG. 14, the original cascade effect of the blade 13 is reduced, and the blade tip vortex β is likely to move away from the suction surface 13e. For this reason, the blade tip vortex β interferes with the adjacent blades 13 earlier than in the case of FIG. 13, and noise is more likely to increase.

  Therefore, as a method for suppressing the blade tip vortex β as described above, as shown in FIGS. 15 to 17, in the impeller 4, the outer peripheral end of the blade 13 is negative starting from a predetermined position Q in the radial direction. There has been proposed one in which a bent portion 13c that is bent in a V shape toward the pressure surface side is formed (see, for example, Patent Document 1). Moreover, in the thing in this patent document 1, the bending part 13c is the bending part 13c with respect to the tangent of the center side part in the predetermined position Q while gradually increasing the width dimension W from the front edge 13a side to the rear edge 13b side. The bending angle θ (see FIG. 16) is increased.

  According to such a configuration, as shown in FIG. 18, the air flow α on the pressure surface 13d side of the blade 13 smoothly flows into the negative pressure surface 13e along the bent portion 13c, and the generated blade tip The vortex diameter of the vortex β is small and stable, and the air flow γ toward the blade outer periphery on the suction surface 13e side does not interfere with the blade tip vortex β. Further, since the width dimension W of the bent portion 13c is increased corresponding to the vortex diameter of the blade tip vortex β that increases from the leading edge 13a side to the trailing edge 13b side, the stabilizing effect by the bent portion 13c is improved. It is exhibited smoothly over the entire region from 13a to the rear edge 13b. For this reason, the generated blade tip vortex β is unlikely to be separated from the suction surface 13e. Further, since the predetermined position Q in the radial direction of the blade 13 is reliably determined as the starting point of the leakage of the air flow α from the pressure surface 13d side to the negative pressure surface 13e side, the amount of leakage of the air flow α is constant, The resulting tip vortex β is stabilized. Further, since the bending angle θ of the bent portion 13c is increased corresponding to the vortex diameter of the blade tip vortex β that increases from the leading edge 13a side to the trailing edge 13b side, the stabilization of the blade tip vortex β is promoted. The scale of the blade tip vortex β can be reduced.

  At the same time, a vertical vortex δ is generated on the pressure surface 13d side of the bent portion 13c due to the separation occurring after the predetermined position Q for determining the starting point. As a result, as shown in FIG. 19, a longitudinal vortex (cancellation vortex) δ generated by a certain blade 13 and a blade 13 adjacent to this blade 13 are located on the front side in the rotational direction F of the impeller 4. The generated blade tip vortex β is separated from the blade surface in the vicinity of the rear edge 13b of each blade 13, and collides in a countercurrent state as shown in FIG. 19, for example, and cancels each other. Further, the vertical vortex δ and the blade tip vortex β cancel each other in this way, so that the discharge vortex in the downstream direction is effectively suppressed.

Special table 2003-72948 gazette

  As described above, the conventional axial blower described in Patent Document 1 effectively stabilizes the vortex by bending the outer peripheral side end of the blade 13 to the negative pressure surface 13e side, and in the downstream direction. The discharge vortex is effectively suppressed.

  By the way, as for the said conventional axial flow fan, as shown in FIG. 20, the bellmouth 5 is formed in the same shape as a general axial flow fan. That is, the bell mouth 5 has a throttle part 52 formed so as to face the outer periphery of the impeller 4 so as to partition the suction area X and the blowout area Y of the blower, and the suction that widens the suction side of the throttle part 52 It has the side opening part 51 and the blowing side opening part 53 which expands the blowing side of this aperture | diaphragm | squeeze part 52. As shown in FIG. The throttle portion 52 is formed as a simple cylindrical hole, and the outer peripheral edge R of the blade 13 is prevented from contacting the bell mouth 5 with the outer peripheral edge R of the operating blade 13. A gap g having a minimum dimension n is formed between the two. The minimum required dimension n includes tolerances that allow for manufacturing errors of the bell mouth 5 and the blades 13 and deformation of the blades 13 due to centrifugal force when the impeller 4 rotates.

  However, since the gap g is a region where the pressure difference between the pressure surface 13d and the negative pressure surface 13e is maximum, as shown in FIG. 21, a very fast leak airflow (hereinafter referred to as jet airflow J and Will occur). The jet air flow J joins the blade tip vortex β and strengthens the blade tip vortex β, so that the loss due to the blade tip vortex β is increased. Further, when this jet airflow J passes through the gap g between the outer peripheral edge R of the blade 13 and the bell mouth 5, it also creates a large turbulence and becomes a factor that increases the noise of the blower.

  Thus, the conventional axial blower has not taken any special measures for reducing the noise caused by the gap g between the bell mouth 5 and the outer peripheral edge R of the blade 13. Therefore, the conventional axial blower still has room for noise improvement in this respect.

  The present invention has been made paying attention to such problems existing in the prior art, and improves noise and efficiency by reducing the jet air flow generated in the gap between the outer peripheral edge of the blade and the bell mouth. An object of the present invention is to provide an axial fan. Moreover, an object of this invention is to provide the outdoor unit for air conditioners and a ventilation fan using such an axial flow fan.

  An axial blower according to the present invention includes an impeller in which a plurality of forward blades are provided on an outer peripheral surface of a hub serving as a rotation center, and a bell mouth provided on the outer periphery of the impeller. Is a throttle part formed opposite to the outer periphery of the impeller so as to partition the suction area and the blowout area of the blower, the suction side opening part that widens the suction side of the throttle part, and the blowout of the throttle part A blow-off side opening that widens the side, and the throttle portion has a minimum dimension between the outer peripheral edge of the blade so that the outer peripheral edge of the blade does not contact the bell mouth during operation. The first throttle part that forms a gap and the second throttle part that forms a gap larger than the necessary minimum dimension between the outer peripheral edge of the blade, and the second throttle part is the first throttle part. It is formed on the outlet side of the throttle part.

  According to the axial blower according to the present invention having such a structural feature, the outer peripheral edge of the blade does not contact the bell mouth during operation between the bell mouth and the outer peripheral edge of the blade. In order to do so, since the first throttle part that forms the gap of the minimum necessary size is formed, the suction area and the suction area can be partitioned from the blower area. In addition, the gap with the necessary minimum dimension is set based on the same idea as the gap with the necessary minimum dimension formed between the bell mouth and the outer peripheral edge of the blade in the conventional axial fan. Things can be used. Therefore, the minimum required dimensions include tolerances that allow for manufacturing errors of the bell mouth and the blades, and deformation of the blades due to the centrifugal force when the impeller rotates, as described above. In addition, when the axial dimension of the bell mouth configured as described above is the same as the axial dimension of the conventional bell mouth, the axial dimension of the first restrictor is reduced by forming the second restrictor. . As a result, the area of the outer peripheral edge of the first constriction part and the outer peripheral edge of the blade that wraps is reduced from the pressure surface side of the blade to the negative pressure surface side. The leaking jet stream becomes slow, and the function of increasing the tip vortex by the jet stream becomes weak. For this reason, a blade tip vortex becomes small and the efficiency of an axial blower increases. In addition, since the jet airflow becomes slow, noise caused by the jet airflow is reduced.

  The second diaphragm portion may be formed on a cylindrical surface parallel to the rotation center axis. Even if comprised in this way, the backflow from the blowing side of a blower to the suction side can be prevented. In addition, since the area of the outer peripheral edge of the blade that wraps with the first throttle part that forms the gap of the minimum necessary dimension between the outer peripheral edge of the blade and the pressure surface side of the blade is reduced. It is possible to slow the jet air leaking into the air. Thereby, the efficiency of the blower can be improved and the noise caused by the jet airflow can be reduced.

  Moreover, the said 2nd aperture | diaphragm | squeezing part is good also as what is formed in the surface which spreads conically toward the blowing side opening part. Even if comprised in this way, the backflow from the blowing side of a blower to the suction side can be prevented. In addition, since the area of the outer peripheral edge of the blade that wraps with the first throttle part that forms the gap of the minimum necessary dimension between the outer peripheral edge of the blade and the pressure surface side of the blade is reduced. It is possible to slow the jet air leaking into the air. Thereby, the efficiency of the blower can be improved and the noise caused by the jet airflow can be reduced.

  The impeller may be arranged such that the axial position of the outer peripheral edge of the trailing edge of the blade substantially coincides with the boundary position between the second throttle portion and the outlet side opening in the bell mouth. preferable. If comprised in this way, since the blowing air current blown so that it may spread from the outer peripheral side of a wing | blade trailing edge may come along the blowing side opening part of a bell mouth, and a blowing air current will decelerate smoothly, the static pressure of a fan Improvements can be made.

  Moreover, it is preferable that the blowing side opening is formed in a conical surface extending to the blowing side, and the blowing side opening can be formed so as to spread on the blowing side by a curved surface such as an arc. However, if configured in this way, the curved surface may protrude with respect to the flow of the blown airflow blown out from the trailing edge of the blade, which may hinder the formation of a smooth airflow. This point conical shape can avoid this fear. Therefore, the blown airflow is blown out so as to diffuse smoothly.

  The outer peripheral end of the blade is formed with a bent portion that is bent toward the suction side, and the width of the bent portion in the radial direction is increased from the front edge toward the rear edge. It is preferable that If comprised in this way, the stabilization effect | action of the blade tip vortex by a bending part and the discharge | release vortex suppression action to a downstream will be added, and the efficiency improvement and noise suppression effect of a fan will improve.

  Moreover, the air conditioner and the ventilating fan according to the present invention are characterized by using the axial flow fan configured as described above as a blower. When such an axial blower is used, since the axial blower is highly efficient and low noise, the efficiency of the air conditioner and the exhaust fan can be improved and the noise can be reduced.

  According to the axial blower according to the present invention, the axial dimension of the throttle part of the bell mouth that forms a gap with the minimum necessary dimension between the outer peripheral edge of the blade is reduced, so that the throttle part is wrapped around the throttle part. The area of the outer peripheral edge of the blade to be reduced becomes smaller. As a result, the jet airflow that leaks from the pressure surface side to the suction surface side in the gap of the minimum necessary size and the periphery thereof becomes slow, and the tip vortex can be reduced. Thereby, while being able to improve the efficiency of an air blower, the noise by jet airflow can be reduced.

It is the schematic cross section which showed the impeller by the rotation locus | trajectory of the axial-flow fan which concerns on embodiment of this invention. It is an enlarged view of the clearance gap formation part of the bell mouth in FIG. 1, and the outer peripheral edge of a blade | wing. It is explanatory drawing which shows the suppression effect | action of the jet airflow in a coaxial air blower. It is a perspective view of the impeller of a coaxial flow blower. It is a top view of the impeller of a coaxial flow blower. It is an enlarged view of the part which forms the clearance gap between a bell mouth and the outer peripheral edge of a blade | wing regarding the axial-flow fan which concerns on a modification. It is a front view of the outdoor unit for air conditioners which employ | adopted the conventional general axial flow fan. It is a longitudinal cross-sectional view of the outdoor unit. It is a horizontal sectional view of the outdoor unit. It is a top view of the impeller of the conventional general axial flow fan mounted in the outdoor unit. It is explanatory drawing which showed the blade tip vortex generation | occurrence | production mechanism in the conventional general axial flow fan on sectional drawing of a blade | wing. It is explanatory drawing which showed on the perspective view of a fan the blade tip vortex generation | occurrence | production mechanism in the same general axial fan. It is the schematic which showed the blade edge vortex interference phenomenon between the adjacent blades of the blade | wing of the same general axial fan. It is the schematic which showed the tip vortex interference phenomenon between adjacent blades in the case of shortening the chord length of a blade | wing in the same general axial flow fan. It is a perspective view of the impeller of the axial-flow fan which concerns on the other conventional example which improved the blade tip vortex. It is sectional drawing which showed the radial direction distribution of the blade | wing of a coaxial flow fan, and the cross section in the same position of a blade | wing, Comprising: (a) is sectional drawing on the line (on the A line in FIG. 17) along a front edge, (B) is a cross-sectional view on the line connecting the center points of the chord lines (on line B in FIG. 17), and (c) is a cross-sectional view on the line along the trailing edge (on line C in FIG. 17). It is a top view of the blade | wing of a coaxial flow fan. It is explanatory drawing which shows the reduction | restoration effect | action of a blade tip vortex and discharge | release vortex in a coaxial flow fan. It is a development view for explanation showing the discharge vortex cancellation action in a coaxial flow blower. It is the schematic cross section which showed the impeller of the coaxial flow blower with the rotation locus. It is explanatory drawing which shows the influence by the jet airflow in a coaxial flow fan.

  An axial blower according to an embodiment of the present invention will be described with reference to FIGS. In addition, in the following description, when describing the part which is common with the conventional axial-flow fan and the air conditioner, the same reference numerals as those in the above description are attached. Moreover, in FIG. 1 to FIG. 5, parts that are the same as those of a conventional axial blower or air conditioner are denoted by the same reference numerals.

  The axial blower according to the present embodiment can be used as a blower such as an air conditioner or a ventilating fan. In this embodiment, the air having the structure as shown in FIGS. It shall be used for outdoor unit for harmony machine. That is, the outdoor unit for an air conditioner is configured such that the main body casing 1 is divided into left and right by the partition plate 7, one is a heat exchange chamber 8 and the other is a machine chamber 9. Air suction ports 1 a and 1 b are formed on the back and side surfaces of the main body casing 1, which are side surfaces, and the blower 3 is installed at the air outlet on the front side of the heat exchange chamber 8.

  Moreover, the blower 3 is the same as what is employ | adopted as the said air conditioner, The fan guard 6 located in the blower side (front side) of the axial-flow fan which consists of the impeller 4 and the bellmouth 5, and an axial-flow fan. It shall be comprised from these.

The axial blower is composed of an impeller 4 and a bell mouth 5 as shown in FIG.
The impeller 4 is shown in FIGS. 1 to 5, and like the conventional general one, the hub 14 and the resin are integrally molded so that the plurality of blades 13 are supported on the outer peripheral surface of the cylindrical hub 14. It is formed by. Further, the blade 13 is a forward wing type in which the position of the outer peripheral edge is positioned forward in the rotational direction F from the position of the hub-side base end S (that is, the inner peripheral edge) at each of the front edge 13a and the rear edge 13b. (See FIGS. 3 to 5).

  The blade 13 is slightly different in specific dimensions and shape as compared with the above-described conventional one shown in FIGS. 15 to 19, but the outer peripheral end portion starts from a predetermined position Q in the radial direction. This is the same in that it includes a bent portion 13c that is bent in a V shape toward the suction surface side. Further, the bent portion 13c gradually increases the radial width W from the front edge 13a side to the rear edge 13b side, and increases the bending angle θ of the bent portion 13c with respect to the tangent of the center side portion at the predetermined position Q. This is the same as the conventional one.

  On the other hand, the bell mouth 5 is formed on the outer periphery of the impeller 4 so as to partition the suction region X and the blowout region Y of the impeller 4 as shown in FIG. Further, the bell mouth 5 has a throttle part 52 formed so as to oppose the outer periphery of the impeller 4 so as to partition the suction area X and the blowout area Y of the blower, and the suction that widens the suction side of the throttle part 52 It has the side opening part 51 and the blowing side opening part 53 which expands the blowing side of this aperture | diaphragm | squeeze part 52. As shown in FIG.

  In the present embodiment, the restricting portion 52 has a minimum dimension n between the outer peripheral edge R of the blade 13 and the outer peripheral edge R so that the outer peripheral edge R of the blade 13 does not contact the bell mouth 5 during operation. The first throttle part 52a that forms a gap g of the second blade and the second throttle part 52b that forms a gap larger than the necessary minimum dimension n between the outer peripheral edge R of the blade 13 and the first throttle part 52a. . Here, the minimum gap n of the dimension n is a minimum gap n of the dimension n formed between the bell mouth 5 and the outer peripheral edge R of the blade 13 in a conventional general axial fan. It is set with the same idea. That is, the minimum required dimension n includes tolerances that allow for manufacturing errors of the bell mouth 5 and the blades 13 and deformation of the blades 13 due to centrifugal force when the impeller 4 rotates.

  The second throttle portion 52b is formed on a cylindrical surface parallel to the rotation center axis O, and is formed on the outlet side of the first throttle portion 52a. On the other hand, the first diaphragm 52a is also formed on a cylindrical surface parallel to the rotation center axis O, but has a shorter axial dimension than the second diaphragm 52b.

  In this embodiment, the suction side opening 51 is a curved surface having a curved longitudinal sectional shape and is continuous with the first throttle part 52a, and is formed so as to expand the first throttle part 52a to the suction side. Yes. Further, the blowing side opening 53 is continuous with the second throttle part 52b at a surface whose longitudinal cross-sectional shape expands in a tapered shape toward the blowing side, that is, a surface expanding in a conical shape, and the second throttle part 52b is expanded toward the blowing side. It is formed to open. Further, the boundary between the second diaphragm 52b and the first diaphragm 52a is formed to be continuous with a small curved surface.

  Further, the relative positional relationship between the bell mouth 5 and the impeller 4 in the axial direction is such that the outer peripheral edge Rb of the rear edge 13b of the impeller 4 is blown out from the second throttle portion 52b of the bell mouth 5 as shown in FIG. It is set to coincide with the boundary with the side opening 53.

Next, the operation of the axial blower according to this embodiment will be described.
When the impeller 4 is rotated by the drive of the motor, the axial blower having the above configuration generates a pressure difference between the suction region X and the blowout region Y of the impeller 4, and air flows from the suction region X toward the blowout region Y. Is sent out.

  At this time, on the outer peripheral edge R side of the blade 13, the blade tip vortex β generated by the air flow α that circulates from the pressure surface 13 d side to the negative pressure surface 13 e side is similar to the conventional one. The amount of leakage of the air flow α is made constant by the bent portion 13c bent in a V shape from the predetermined position Q in the radial direction toward the suction surface side, and the vortex diameter is reduced and stabilized. Further, the blade tip vortex β acts so as to cancel each other by the collision with the longitudinal vortex δ generated by the separation generated after the predetermined position Q on the pressure surface 13d side of the bent portion 13c at the rear in the rotation direction.

  On the other hand, between the bell mouth 5 and the impeller 4, as shown by arrows in FIG. 2, the air sucked from the outer peripheral side of the impeller 4 is a curved surface having a large curvature radius in the suction side opening 51 of the bell mouth 5. As a result, the air flows along the curved surface of the suction side opening 51 and is sucked.

  Further, in the gap g having the minimum required dimension n formed between the first throttle portion 52a of the bell mouth 5 and the outer peripheral edge R of the blade 13, as shown in FIG. Since the pressure difference with the pressure surface 13e becomes the maximum region, a very fast leak airflow (jet airflow J) is generated. However, since the second diaphragm portion 52b is formed, the axial dimension of the first diaphragm portion 52a is smaller than that of the conventional one, so that the outer peripheral edges of the first diaphragm portion 52a and the blade 13 are formed. The overlap dimension with R becomes small, and the jet airflow J generated there is weaker than the conventional one. For this reason, the influence of the jet airflow J on the blade tip vortex β is reduced, the blade tip vortex β is reduced, and the efficiency of the axial fan is increased. Moreover, since the jet airflow J becomes slow, the noise caused by the jet airflow J is reduced.

  Moreover, in the blowing side opening part 53 between the bell mouth 5 and the impeller 4, since the blowing side opening part 53 is comprised so that a cross-sectional cone may spread, the air which blows off from the impeller 4 to radial direction Flows along the conical blowout side opening 53 to achieve a smooth flow.

As described above, according to the axial fan according to the present embodiment, the following effects can be obtained.
(1) Between the bell mouth 5 and the outer peripheral edge R of the blade 13, in order to prevent the outer peripheral edge R of the blade 13 from contacting the bell mouth 5 during operation, Since the first throttle part 52a that forms the gap g is formed, the blowout area Y and the suction area X of the blower can be partitioned.

  (2) Since the overlap dimension between the first narrowed portion 52a forming the gap g having the minimum necessary dimension n and the outer peripheral edge R of the blade 13 is small, the jet airflow J generated in the gap g is larger than that of the conventional one. It becomes weaker and has less influence on the tip vortex β. As a result, the efficiency of the axial blower is improved and the noise caused by the jet airflow J is reduced.

(3) Since the blowout side opening 53 of the bell mouth 5 is configured to expand in a conical section, the blowout in the radial direction from the impeller 4 is smoothly performed.
(4) In the impeller 4, the position in the axial direction of the outer peripheral edge Rb of the trailing edge 13 b of the blade 13 is substantially coincident with the boundary position between the second throttle portion 52 b and the outlet side opening 53 in the bell mouth 5. Is arranged. Therefore, since the blown air flow blown out from the impeller 4 so as to spread on the outer peripheral side is along the blow-side opening 53 of the bell mouth 5, the blown air flow is smoothly decelerated, so that the static pressure of the blower is improved. Can be planned.

  (5) A bent portion 13c that is bent toward the suction surface side is formed at the outer peripheral end portion of the blade 13, and the radial width W of the bent portion 13c increases from the front edge 13a toward the rear edge 13b. Thus, the stabilizing effect of the blade tip vortex β by the bent portion 13c and the action of suppressing the discharge vortex to the downstream side are added to improve the efficiency and reduce the noise of the blower.

  (6) Moreover, since the air conditioner and ventilation fan which concern on this invention use the axial flow fan comprised as mentioned above as an air blower, according to the efficiency improvement and noise reduction of an axial flow fan, an air conditioner and a ventilation fan Efficiency and noise reduction.

(Modification)
The above embodiment can be modified as follows.
The second throttle portion 52b is formed on a cylindrical surface parallel to the rotation center axis O, but as shown in FIG. 6, it is formed on a surface that extends conically toward the outlet side opening 53. It is good as it is. Even if comprised in this way, the backflow from the blowing side of a blower to the suction side can be prevented. Moreover, since the area | region of the outer periphery edge R of the blade | wing 13 which overlaps with the 1st aperture | diaphragm | squeeze part 52a which forms the clearance gap g of the minimum necessary dimension between the outer periphery edge R of the blade | wing 13 becomes small, the pressure of the blade | wing 13 The jet airflow J leaking from the surface 13d side to the negative pressure surface 13e side can be slowed. Thereby, the efficiency of the blower can be improved and the noise caused by the jet airflow J can be reduced.

-In above-mentioned embodiment, although the suction side opening part 51 is formed in the curved surface of a big curvature radius, you may make this into a conical surface.
-Although the blowing side opening part 53 is formed in the cone shape in the said embodiment, it can also be formed so that this may spread on the blowing side with curved surfaces, such as a circular arc. However, in the case of such a configuration, there is a possibility that the curved surface protrudes with respect to the flow of the blown air flow blown out from the trailing edge 13b of the blade 13 and obstructs the formation of a smooth air flow. This point conical shape can avoid this fear.

  In the previous embodiment, the position in the axial direction of the outer peripheral edge Rb of the trailing edge 13 b of the blade 13 is substantially coincident with the boundary position between the second throttle portion 52 b and the outlet side opening 53 in the bell mouth 5. However, the present invention includes those not arranged at such positions. However, when the position in the axial direction of the outer peripheral edge Rb of the rear edge 13b is on the suction side from the boundary position between the second throttle part 52b and the outlet side opening 53, the outer edge Rb of the rear edge 13b is blown out. There is a possibility that the airflow spreading in the radial direction interferes with the second throttle part 52b to generate turbulence and increase the blowing sound. Further, when the axial position of the outer peripheral edge Rb of the rear edge 13b is on the outlet side from the boundary position between the second throttle part 52b and the outlet side opening 53, the rear edge 13b is blown from the outer peripheral edge Rb of the rear edge 13b. There is a possibility that the airflow spreading outward in the radial direction interferes with the induced airflow generated by the main blown airflow and the blowing sound increases.

  -Although this invention can be applied also to what does not form the bending part 13c in the outer peripheral edge part of the blade | wing 13, the direction in which the bending part 13c is formed is a viewpoint from the viewpoint of the noise reduction of a fan, and an efficiency improvement. preferable.

  The axial blower according to the present invention reduces noise and power increase due to jet airflow in a wide range of flow rates, so it can be used not only for outdoor units of air conditioners but also for various devices such as ventilators and air purifiers. Widely used.

  g ... gap, n ... dimension, β ... blade tip vortex, J ... jet airflow, O ... rotation center axis, Q ... (radial direction) predetermined position, R ... outer edge, Rb ... outer edge Edge, W ... Width dimension, X ... Suction area, Y ... Blowout area, 3 ... Blower, 4 ... Impeller, 5 ... Belmouth, 13 ... Vane, 13a ... Front edge, 13b ... Rear edge, 13c ... Bending part , 13d ... pressure surface, 13e ... negative pressure surface, 14 ... hub, 51 ... suction side opening, 52 ... throttle part, 52a ... first throttle part, 52b ... second throttle part, 53 ... blowout side opening part.

Claims (8)

An impeller in which a plurality of forward wing type blades are provided on the outer peripheral surface of the hub serving as a rotation center, and a bell mouth provided on the outer periphery of the impeller,
The bell mouth includes a throttle portion formed to face the outer periphery of the impeller so as to partition the suction region and the blowout region of the blower, a suction side opening portion that widens the suction side of the throttle portion, and the throttle A blowing side opening that widens the blowing side of the part,
The throttle portion includes a first throttle portion that forms a gap with a minimum size between the outer peripheral edge of the blade and the outer peripheral edge of the blade so that the outer peripheral edge of the blade does not contact the bell mouth during operation. A second throttle part that forms a gap larger than the necessary minimum dimension with the edge, and the second throttle part is formed on the outlet side of the first throttle part. Axial flow blower.   The axial blower according to claim 1, wherein the second throttle part is formed on a cylindrical surface parallel to the rotation center axis.   The axial blower according to claim 1, wherein the second throttle portion is formed on a surface that expands in a conical shape toward the outlet side opening.   The impeller is arranged such that the axial position of the outer peripheral edge of the trailing edge of the blade is substantially coincident with the boundary position between the second throttle portion and the outlet side opening in the bell mouth. The axial blower according to any one of claims 1 to 3.   The axial blower according to any one of claims 1 to 4, wherein the blowout side opening is formed in a conical surface extending to the blowout side.   A bent portion that is bent toward the suction surface side is formed at the outer peripheral end portion of the blade, and further, the radial width of the bent portion is formed so as to increase from the front edge toward the rear edge. The axial-flow fan according to any one of claims 1 to 5.   The air conditioner which used the axial-flow fan of any one of Claims 1-6 as an air blower of an outdoor unit.   The ventilation fan which used the axial-flow fan of any one of Claims 1-6 as an air blower.

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