JP6073605B2 - Centrifugal blower - Google Patents

Description

  The present invention relates to a centrifugal blower in which a fan having a plurality of blades is accommodated between a bottom plate and a rim in a scroll casing, and more particularly to a fan using a fan whose inner diameter becomes smaller toward the bottom plate side.

  Conventionally, for example, a centrifugal blower used for a vehicle air conditioner or the like stores a fan configured by providing a plurality of blades (wings) between a bottom plate fixed to a rotating shaft and an annular rim in a scroll casing, A spiral flow path is formed around the fan in the scroll casing. When the fan is rotated by the electric motor, air inside the blade in the radial direction is discharged to the outside in the radial direction, so that air is sucked from the suction port formed on one end side in the axial direction of the rotating shaft, and the spiral flow It blows out of a scroll casing from the blower outlet formed in the downstream through the path.

  In this case, if a large amount of air flows between the winding end and the winding start of the spiral flow path, the air flow rate decreases and the specific noise increases, so the scroll casing is wound from the winding end of the spiral flow path. A tongue portion that suppresses the inflow of air to the beginning is formed. In addition, a curved bell mouth is formed around the suction port to introduce air into the fan (impeller) (see, for example, Patent Document 1).

  In the case of Patent Document 1, each blade (blade) extends in parallel with the rotating shaft of the electric motor, but the inner diameter (the length of a line passing between the inner ends of the blades through the center of the rotating shaft). There is also a fan that uses a fan that gradually decreases from the rim side toward the bottom plate side (see, for example, Patent Document 2). When such a fan is used, the flow of air (blade air) flowing in from the suction port becomes easier to flow into the bottom plate as it is because the inner end side of the blade is inclined, and as a result, the flow velocity flowing out from the blade Is made uniform. Compared to a fan in which the blade extends in parallel with the rotating shaft of the electric motor as in Patent Document 1, the flow rate of air flowing out from the bottom plate side is reduced, and the generation of vortices is reduced. , Noise is reduced.

  In addition, the inlet angle at the inlet (inner end) of the blade substantially matches the inflow angle of the air sucked from the suction port and flowing into the blade (the direction when the air flows into the blade and the extending direction of the blade are substantially orthogonal ). In other words, since air sucked from the suction port flows at an angle close to perpendicular to the blades, air turbulence hardly occurs between the blades, and noise is reduced.

JP 2008-280939 A Japanese Patent Publication No. 7-94838

  Here, the noise generated when the air blown from the fan collides with the tongue is a problem. The reason will be described with reference to the schematic diagram of FIG. In the case of a fan in which each blade (blade) extends in parallel with the rotating shaft of the electric motor as in Patent Document 1, when the velocity distribution of the air flowing out from the fan is viewed, generally the electric motor side (see FIG. The speed on the bottom plate side indicated by LWR in 8 is higher. In addition, since the air flow flowing out from the fan includes many vortices, noise is generated when the vortex collides with the tongue.

  On the other hand, in the case of a normal tongue 100 whose tip is parallel to the rotating shaft of the electric motor, a corner 100A on the suction port side (indicated by UPR in FIG. 8) of the tongue 100 and a corner on the electric motor side (LWR) In 100B, a stagnation area exists. For this reason, shearing turbulence due to the flow of air flowing out from the fan and this stagnation region and noise due to the secondary flow are generated, so that the noise caused by the tongue increases as a whole, combined with the above-described vortex noise There was a problem.

  Also, there is a problem with noise when air flows from the bell mouth to the fan. This will be described with reference to the schematic diagram of FIG. In FIG. 16, a bell mouth 103 is formed around a suction port 102 formed in the scroll casing 101 on one end side of the rotation shaft, and each blade 106 is connected to the rotation shaft of the electric motor as in Patent Document 1 described above. In the case of the fan 104 extending in parallel, the flow of air flowing in from the bell mouth 103 due to the rotation of the fan 104 flows toward the lower side of the blade 106 (on the electric motor side) and is concentrated.

  On the other hand, above the blade 106 (on the suction port side), there is almost no inflow into the blade 106 due to peeling at the tip of the bell mouth 103, and the blade 106 is in a stagnation state (FIG. 16). For this reason, the air flow concentrated below the blade 106 has a locally high flow velocity distribution. In the case of this kind of centrifugal blower, noise increases in proportion to the sixth power of the air flow rate (Lighthill theory).

  The present invention has been made to solve the conventional technical problem, and in a centrifugal blower using a fan whose inner diameter becomes smaller toward the bottom plate side, a tongue portion and a bell mouth formed on a scroll casing The object is to effectively suppress noise caused by the shape of the.

In order to solve the above-mentioned problem, the centrifugal blower of the invention of claim 1 includes a bottom plate fixed to the rotating shaft, a plurality of blades whose bases are fixed to the outer periphery of the bottom plate, and coaxial with the bottom plate. A fan that is provided and has an annular rim that connects the tip of the blade, the inner diameter of which becomes smaller toward the bottom plate side, and a scroll that houses the fan and has a suction port on one end side in the axial direction of the rotating shaft Rotating the tongue, comprising a casing, a spiral channel formed around the fan in the scroll casing, and a tongue that suppresses the inflow of air from the end of winding of the spiral channel to the start of winding portion of the other axial end of the shaft is inclined so that the dimensions overhanging reverse rotation direction of the fan is increased toward the other axial end of the rotary shaft, the tongue When the dimension in the axial direction of the rotary shaft is H and the dimension in the axial direction of the rotary shaft from the end on the other end side in the axial direction of the rotary shaft of the tongue is Z1, 0.2 ≦ Z1 /H≦0.6 .

The centrifugal blower of the invention of claim 2 is characterized in that in the above invention, Z1 / H = 0.4.

In the centrifugal blower of the invention of claim 3 , in each of the above inventions, the dimension of the portion of the tongue portion on the one end side in the axial direction of the rotating shaft increases in the anti-rotation direction of the fan toward the one end side in the axial direction of the rotating shaft. It is characterized by tilting.

According to a fourth aspect of the present invention, the centrifugal blower of the present invention has the dimension H in the axial direction of the rotating shaft of the tongue portion in the above invention, and one axial end of the rotating shaft of the tongue portion from the end portion on the other axial end side of the rotating shaft of the tongue portion. When the dimension in the axial direction of the rotating shaft up to the point at which it starts to project on the side is Z2, 0.4 ≦ Z2 / H ≦ 0.9.

The centrifugal blower of the invention of claim 5 is characterized in that Z2 / H = 0.6 in the above invention.

The centrifugal blower of the invention of claim 6 is characterized in that, in each of the above inventions, the end portion of the tongue portion and the corner portion of the point where the protrusion starts are smoothly curved.

In the centrifugal blower of the invention of claim 7 , in each of the above inventions, the scroll casing around the suction port is formed with a standing wall, and the surface of the standing wall on the suction port side is curved like a bell mouth, The dimension from the shaft center to the inner end of the blade is Rf1, the dimension from the shaft center of the rotating shaft to the tip of the surface on the suction port side of the standing wall is R1, and the dimension of the surface on the suction port side of the standing wall from the shaft center of the rotating shaft When the dimension to the inner end is R2, 1 ≦ R1 / Rf1 ≦ 1.1 and 0.94 ≦ R2 / R1 ≦ 1 are satisfied.

The centrifugal blower according to an eighth aspect of the present invention is the above-described invention, wherein R1 / Rf1 = 1.06 and R2 / R1 = 0.98, or R1 / Rf1 = 1.06, and R2 / R1 = 0.95. It is characterized by that.

The centrifugal blower of the invention of claim 9 is provided with a bottom plate fixed to the rotating shaft, a plurality of blades having a base fixed to the outer periphery of the bottom plate, and coaxially provided with the bottom plate, A fan composed of an annular rim to be connected and having an inner diameter that decreases toward the bottom plate, a scroll casing that houses the fan and has a suction port on one end side in the axial direction of the rotating shaft, and the inside of the scroll casing The scroll casing around the suction port is formed with an upright wall, and the surface of the upright wall on the suction port side is curved in a bell mouth shape. Rf1 is the dimension from the axis center of the blade to the inner end of the blade, R1 is the dimension from the axis center of the rotating shaft to the tip of the surface on the suction port side of the upright wall, and the axis of the rotating shaft When the heart has the dimensions to the inner end of the inlet-side surface of the upright wall and R2, R1 / Rf1 = 1.06, and, R2 / R1 = 0.98, or, R1 / Rf1 = 1.06, And R2 / R1 = 0.95.

A centrifugal blower according to a tenth aspect of the present invention includes a blower outlet positioned downstream of the end of winding of the spiral flow passage in each of the above-described inventions, and the height in the axial direction of the rotation axis of the scroll casing is the height of the spiral flow passage. It is characterized by gradually expanding from the beginning of winding toward the outlet.

  According to the first aspect of the present invention, the bottom plate fixed to the rotating shaft, the plurality of blades whose bases are fixed to the outer periphery of the bottom plate, the coaxially provided with the bottom plate, and connecting the tip portions of the blades A scroll casing having a suction port on one end side in the axial direction of the rotating shaft, and a fan in the scroll casing. In a centrifugal blower including a spiral flow path configured around the spiral passage and a tongue that suppresses the inflow of air from the end of winding of the spiral flow path to the start of winding, the axial direction of the rotation axis of the tongue, etc. Since the end portion is inclined so that the dimension of the fan projecting in the counter-rotating direction increases toward the other axial end of the rotating shaft, the rotating shaft of the tongue is increased. Stagnation region disappears occurring in the corner in the other axial end side and thereby possible to reduce the noise due to shear turbulence and secondary flows occur.

  In addition, since the inner diameter of the fan is set smaller toward the bottom plate side, the air flow (blade air) flowing in from the suction port is tilted on the inner end side of the blade, so that the bottom plate side ( As a result, the flow velocity flowing out from the blade is made uniform from the bottom plate side to the rim side (one axial end side of the rotating shaft). Thereby, the noise is reduced by reducing the flow velocity of the air flowing out from the bottom plate side and reducing the generation of vortices.

  In addition, the inlet angle at the inlet (inner end) of the blade substantially matches the inflow angle of the air sucked from the suction port and flowing into the blade (the direction when the air flows into the blade and the extending direction of the blade are substantially orthogonal ). As a result, the air sucked from the suction port flows in at an angle close to perpendicular to the blades, so that air turbulence hardly occurs between the blades, and noise is reduced.

In particular, when the dimension in the axial direction of the rotating shaft of the tongue is H, and the dimension in the axial direction of the rotating shaft from the end of the other end in the axial direction of the rotating shaft of the tongue is Z1, 0 Since 2 ≦ Z1 / H ≦ 0.6, it is possible to effectively reduce noise. By setting Z1 / H = 0.4 as in the second aspect of the invention, more effective noise reduction can be achieved. It becomes possible to plan.

Further, as in the third aspect of the invention, the portion of the tongue portion on the one end side in the axial direction of the rotating shaft is also inclined so that the dimension protruding in the counter-rotating direction of the fan increases toward the one end side in the axial direction of the rotating shaft. For example, the stagnation region generated at the corner on one end side in the axial direction of the rotating shaft of the tongue portion can be eliminated to further reduce noise.

  In particular, the inner diameter of the fan is reduced toward the bottom plate side, and the air velocity distribution from the bottom plate side to the rim side of the blade is smaller than that of the fan in which the blade extends in parallel with the rotating shaft of the electric motor. Therefore, by inclining both the portion on the other end side in the axial direction of the rotation axis of the tongue portion and the portion on the one end side, the shape of the tongue portion conforms to the velocity distribution. Thereby, the noise in a tongue part is reduced more effectively compared with the fan with which a braid | blade extends in parallel with the rotating shaft of an electric motor.

In this case, the dimension in the axial direction of the rotating shaft of the tongue portion is H as in the invention of claim 4 , and the end portion on the other end side in the axial direction of the rotating shaft of the tongue portion projects from one end side in the axial direction of the rotating shaft of the tongue portion. When the dimension in the axial direction of the rotating shaft up to the starting point is Z2, if 0.4 ≦ Z2 / H ≦ 0.9, noise can be reduced more effectively, and Z2 as in the invention of claim 5 By setting /H=0.6, the most effective noise reduction can be realized.

Furthermore, if the end portion of the tongue and the corner portion where the protrusion starts are curved smoothly as in the invention of claim 6 , further noise reduction can be expected.

According to the seventh aspect of the present invention, the rising wall is formed in the scroll casing around the suction port, and the surface on the suction port side of the standing wall is curved in a bell mouth shape, and the blade is formed from the shaft center of the rotating shaft. Rf1 is the dimension from the axis center of the rotating shaft to the tip of the surface on the suction port side of the upright wall, R1 is the dimension from the axis center of the rotating shaft to the inner end of the surface on the suction port side of the standing wall When the dimension is R2, since 1 ≦ R1 / Rf1 ≦ 1.1 and 0.94 ≦ R2 / R1 ≦ 1, the air flowing from the suction port due to the rotation of the fan is raised by the Coanda effect. It flows along the bell mouth-shaped surface on the suction port side, and easily flows into one axial end side of the rotating shaft of the blade.

  As a result, the inflowing air does not concentrate on the other axial end side of the blade rotation shaft, and the air flow rate becomes uniform between the blades in the axial direction of the blade rotation shaft. Accordingly, since the high speed is locally eliminated, noise is reduced.

If R1 / Rf1 = 1.06 and R2 / R1 = 0.98 as in the invention of claim 8 , the noise can be suppressed most, R1 / Rf1 = 1.06, and If R2 / R1 = 0.95, the operating efficiency can be maintained in a good state.

According to the invention of claim 9, a bottom plate fixed to the rotating shaft, a plurality of blades having a base fixed to the outer periphery of the bottom plate, and a tip of the blade provided coaxially with the bottom plate A fan having an inner diameter that decreases toward the bottom plate, a scroll casing that houses the fan and has a suction port on one end side in the axial direction of the rotating shaft, and the inside of the scroll casing The scroll casing around the suction port is formed with a standing wall, and the surface on the suction port side of the standing wall is curved in a bell mouth shape and rotates. The dimension from the axis center of the shaft to the inner end of the blade is Rf1, the dimension from the axis center of the rotating shaft to the tip of the surface on the suction port side of the standing wall is R1, the axis of the rotating shaft R1 / Rf1 = 1.06 and R2 / R1 = 0.98, or R1 / Rf1 = 1.06, where R2 is the dimension from the center to the inner end of the surface on the suction port side of the standing wall Since R2 / R1 = 0.95, the air flowing in from the suction port due to the rotation of the fan flows along the bell mouth surface on the suction port side of the upright wall due to the Coanda effect, and the rotation axis of the blade It becomes easy to flow into the axial direction one end side. As a result, the inflowing air does not concentrate on the other axial end side of the blade rotation shaft, and the air flow rate becomes uniform between the blades in the axial direction of the blade rotation shaft. Accordingly, since the high speed is locally eliminated, noise is reduced. By setting R1 / Rf1 = 1.06 and R2 / R1 = 0.98, the noise can be suppressed most, R1 / Rf1 = 1.06, and R2 / R1 = 0. .95 makes it possible to maintain the driving efficiency in a good state.

According to the invention of claim 10 , in each of the above inventions, the air outlet is provided downstream of the end of winding of the spiral flow path, and the height in the axial direction of the rotation axis of the scroll casing is the spiral flow path. Since it gradually expands from the beginning of winding toward the outlet, it flows out of the fan from the bottom plate side (the other axial end of the rotating shaft) of the blade to the rim side (one axial end of the rotating shaft) The speed of the air on the rim side, which has increased in speed due to the uniform air speed distribution, tends to decrease.

  That is, the air flowing out from the rim side of the fan is made uniform by decreasing the inner diameter of the fan toward the bottom plate side, and the blade is higher than the fan extending in parallel with the rotating shaft of the electric motor. Since the speed decreases smoothly after exiting the spiral flow path in the scroll casing, the effect of reducing noise by further increasing the height of the scroll casing in the axial direction can be further improved. You will be able to enjoy it.

It is a perspective view of a centrifugal blower to which the present invention is applied. It is a side view of the centrifugal blower of FIG. It is a vertical side view of the centrifugal blower of FIG. It is a plane sectional view of the centrifugal blower of FIG. It is the sectional view on the AA line of FIG. The dimension in the axial direction of the rotating shaft of the tongue portion is H, and the dimension in the axial direction of the rotating shaft from the end portion on the other end side in the axial direction of the rotating shaft of the tongue portion to the point where it begins to project on the other end side in the axial direction of the rotating shaft. It is the figure which measured the relationship between Z1 / H and specific noise when it was set to Z1. Relationship between Z2 / H and specific noise when the dimension in the axial direction of the rotating shaft from the end on the other axial end of the rotating shaft of the tongue portion to the point at which it begins to project on one axial end of the rotating shaft is Z2. It is the figure which measured. When the tip of the tongue is parallel to the rotating shaft and the blade is a fan extending in parallel to the rotating shaft of the electric motor, it is a schematic diagram showing the flow of air flowing out from the fan and the stagnation region. . The fan in the present invention when the axial direction other end side and one end side portion of the rotating shaft of the tongue portion are respectively inclined so that the dimension protruding in the counter-rotating direction of the fan increases toward the other end side and the one end side. It is a schematic diagram which shows the flow of the air which flows out out of. The blade is electrically driven when the axially opposite end and one end of the rotating shaft of the tongue are inclined so that the dimension of the fan protruding in the counter-rotating direction increases toward the other end and one end. It is a schematic diagram which shows the flow of the air which flows out from the fan extended in parallel with the rotating shaft of a motor. It is a figure explaining the specific noise reduction effect in the case of FIG. It is an expansion vertical side view of the suction inlet part of the centrifugal blower of FIG. It is the figure which measured the relationship between L / D, specific noise, and fan efficiency when the diameter of a fan is D and the standing dimension of the standing wall around a suction inlet is L. R1 / Rf1 and specific noise and fan when the dimension from the axis center of the rotating shaft to the inner end of the blade is Rf1, and the dimension from the axis center of the rotating shaft to the tip of the surface on the suction port side of the standing wall is R1 It is the figure which measured the relationship of efficiency. It is the figure which measured the relationship between R2 / R1, specific noise, and fan efficiency when the dimension from the axial center of a rotating shaft to the inner end of the surface by the side of the suction port of a standing wall is set to R2. It is a schematic diagram of the inlet port part which shows the flow of the air which flows in into the fan from which a braid | blade extends in parallel with the rotating shaft of an electric motor from a normal bell mouth-shaped inlet port. It is a schematic diagram of a suction port portion showing a flow of air flowing from the suction port into the fan in the present invention when a standing wall is formed around and the surface on the suction port side is formed in a bell mouth shape. A suction port portion that shows the flow of air that flows from the suction port into the fan that extends parallel to the rotation axis of the electric motor when the standing wall is configured around and the surface on the suction port side is a bell mouth shape. It is a schematic diagram. It is a figure explaining the flow of the air in the scroll casing which flowed out to the spiral flow path from the fan.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The centrifugal blower 1 of an Example is used for the ventilation unit of a vehicle air conditioner, and is arrange | positioned between the inside-and-outside air switching damper which is not shown in figure, and a heat exchanger (evaporator).

  1 to 4, the centrifugal blower 1 includes an electric motor 2 serving as a driving unit, an inverted frustoconical fan 3 that is rotationally driven by the electric motor 2, and a scroll casing 4. The fan 3 has a bottom plate 6, and a substantially conical cone portion 6 </ b> A bulging in the axial direction of the fan 3 is formed at the center of the bottom plate 6. A boss portion 6B is formed at the center of the cone portion 6A, and the boss portion 6B is fitted to the rotating shaft 7 of the electric motor 2.

  The outer periphery of the bottom plate 6 has a bowl shape, and the base ends of a plurality of blades (wings) 8 are fixed on the outer periphery. These blades 8 are arranged concentrically around the rotating shaft 7 of the electric motor 2. A predetermined interval is secured between these blades 8, and the tip of the blade 8 is connected by an annular rim 9 provided coaxially with the bottom plate 6.

  In particular, the fan 3 according to the present invention is such that the inner diameter (the length of a line extending between the inner ends of the blades 8 through the axial center of the rotating shaft 7) gradually decreases from the rim 9 side toward the bottom plate 6 side. Designed (Figure 3).

  And this fan 3 is accommodated in the said scroll casing 4 made from hard resin, for example, and the scroll casing 4 comprises a part of duct of the said ventilation unit. That is, the scroll casing 4 has a suction port 11, an air outlet 12, and an internal flow path, and the fan 3 is inserted in the internal flow path.

  The scroll casing 4 has an outer peripheral wall 13 positioned in the radial direction of the fan 3, and the air outlet 12 opens at the end of the outer peripheral wall 13. As shown in FIGS. 1, 2, and 4, the outer peripheral wall 13 includes a scroll wall portion 14 extending in a predetermined spiral shape, and the scroll wall portion 14 extends from the beginning of the spiral to the rotation direction of the fan 3. As the angle increases, the radial distance from the center of the rotation shaft 7 (the center of the fan 3) is gradually increased.

  The outer peripheral wall 13 further includes a tongue portion 16 located at the beginning of the spiral winding, a flat surface portion 17 continuous to the outside of the tongue portion 16, and a tangential portion 18 continuous at the end of the spiral winding. The air outlet 12 is formed between the end portions of the flat portion 17. The outer peripheral wall 13 defines a spiral flow path 19 extending spirally around the fan 3, and the spiral flow path 19 constitutes a part of the flow path inside the scroll casing 4.

  Further, the radial distance between the outer peripheral wall 13 and the fan 3 is the smallest at the tongue portion 16, and the tongue portion 16 is located at the upstream end of the spiral flow passage 19 and is wound around the spiral flow passage 19. It plays the role of suppressing the inflow of air from the end to the beginning of winding. The details of the tongue 16 will be described later. And the said blower outlet 12 is located in the downstream end of the winding end of this spiral flow path 19. FIG.

  1 to 3, the scroll casing 4 has a first end wall 21 positioned on one end side (tip side) in the axial direction of the rotary shaft 7 and the other end side in the axial direction of the rotary shaft 7 (electric motor 2). The outer peripheral wall 13 extends between the outer edges of the first end wall 21 and the second end wall 22, and forms the spiral channel 19 together therewith.

  The second end wall 22 on the electric motor 2 side is a wall parallel to a plane orthogonal to the axis of the fan 3 (axial direction of the rotating shaft 7), and the second end wall 22 of the bottom plate 6 of the fan 3 is viewed from the axial direction of the fan 3. Located in the vicinity. A motor mounting hole 24 into which the main body 23 of the electric motor 2 is fitted is formed in the second end wall 22, and the wall of the second end wall 22 surrounding the motor mounting hole 24 faces the bottom plate 6 of the fan 3. In addition, a wall located on the downstream side of the spiral flow path 19 that extends from the tangential portion 18 and the flat portion 17 extends.

  On the other hand, the suction port 11 is formed in the first end wall 21 located on one end side in the axial direction of the rotary shaft 7, and the suction port 11 is positioned coaxially with the fan 3. Around the suction port 11, the upright wall 26 is shaped so that it stands up substantially perpendicularly (in the axial direction of the rotary shaft 7) in the direction away from the fan 3 from the first end wall 21, and then is folded back toward the suction port 11. The surface of the standing wall 26 on the suction port 11 side is curved like a bell mouth. Hereinafter, this curved portion is referred to as a bell mouth 27. The suction port 11 is formed inside the bell mouth 27, and the inner diameter thereof is set smaller than the inner diameter of the rim 9. Details of the bell mouth 27 will be described later.

  Further, the height of the first end wall 21 in the axial direction of the rotating shaft 7 (the distance from the second end wall 22) is blown from the beginning of the spiral flow path 19 as shown in FIGS. It is inclined at a predetermined angle so as to gradually expand toward the outlet 12. Thereby, the flow path cross-sectional area of the spiral flow path 19 is configured to gradually expand from the upstream (start of winding) to the downstream (end of winding).

  When electric power is supplied to the electric motor 2 of the centrifugal blower 1, the electric motor 2 drives the fan 3 to rotate clockwise in FIG. When the fan 3 is driven and the blades 8 are rotated, the blades 8 push out the air within the interval defined between the blades 8 to the outside in the radial direction. Thereby, the air flow which goes to radial direction outer side through a space | interval from the radial inside of the fan 3 is produced | generated. Along with the generation of this air flow, air flows into the scroll casing 4 through the bell mouth 27 of the suction port 11, and this inflowed air is the distance between the blades 8 of the fan 3, the spiral channel 19 and the outlet. 12 flows out of the scroll casing 4.

  At this time, the tongue portion 16 is present at the beginning of the spiral flow path 19, and the radial distance between the outer peripheral wall 13 and the fan 3 is set to be the smallest in the tongue portion 16. Inflow of air from the winding end to the winding start of the flow channel 19 is suppressed. Thereby, the fall of the ventilation volume and the increase of a specific noise by many air distribute | circulating between a winding end side and a winding start side will be eliminated.

  Here, as shown in FIG. 16, in the case of a fan in which the blade extends in parallel with the rotating shaft of the electric motor, the air flowing in from the suction port flows toward the bottom plate of the fan blade and is concentrated. In the case of the fan 3 as in the present invention, where the inner diameter gradually decreases toward the bottom plate side, the air flow (blade air) flowing in from the suction port 11 is inclined on the inner end side of the blade 8. It becomes easy to flow into the bottom plate 6 side as it is. Therefore, the flow velocity flowing out from the blade 8 is made uniform from the bottom plate 6 side to the rim 9 side as compared with a fan (see FIG. 16) in which the blade extends in parallel with the rotating shaft of the electric motor. Note that the flow velocity of the air flowing out from the fan 3 has a circumferential component and a radial component, but both components are made uniform. Thereby, the noise is reduced by reducing the flow velocity of the air flowing out from the bottom plate 6 side and reducing the generation of vortices.

  Further, since the inner diameter of the fan 3 gradually decreases toward the bottom plate 6, the inlet angle at the inlet portion (inner end) of the blade 8 is larger than the inlet angle of the air sucked from the suction port 11 and flowing into the blade 8. They are substantially matched (the direction when air flows into the blade 8 and the extending direction of the blade are substantially orthogonal). As a result, air sucked from the suction port 11 flows into the blade 8 at an angle close to perpendicular to the blade 8, so that air turbulence hardly occurs between the blades 8, and noise is reduced.

  The height of the first end wall 21 of the scroll casing 4 in the axial direction of the rotary shaft 7 (distance between the second end wall 22) gradually increases from the beginning of the spiral flow path 19 toward the outlet 12. The effect of inclining at a predetermined angle so as to expand will be described in detail later.

(Shape of tongue 16)
Next, the shape of the tongue portion 16 of the scroll casing 4 according to the embodiment will be described with reference to FIGS. The inventor examined the shape of the tongue 16 in order to reduce the noise. 5 shows a cross-sectional view taken along line AA of FIG. 4, and FIGS. 6, 7 and 11 show the verification results. 9 and 10 are schematic diagrams for explaining the verification results.

  As described above, the velocity distribution of the air flowing out from the fan in which the blade extends in parallel with the rotating shaft of the electric motor is higher on the electric motor side (the bottom plate side indicated by LWR in FIGS. 8 and 10). Become. The air flow flowing out from the fan 3 includes many vortices. On the other hand, in the case of the fan 3 as in the present invention in which the inner diameter gradually decreases toward the bottom plate side, the velocity distribution of the air flowing out from the fan 3 is more uniform from the bottom plate 6 side to the rim 9 side of the blade 8. It becomes.

  However, although there are few vortices in the flow, noise is generated when the vortex collides with the tongue 16. 8 is a normal tongue 100 whose tip is parallel to the rotating shaft 7 of the electric motor 2, the corner 100A on the suction port side (indicated by UPR in FIG. 8) of the tongue 100 is provided. Then, a stagnation region is inevitably generated in the corner 100B on the electric motor 2 side (LWR). For this reason, shear disturbance due to interference between the air flow flowing out from the fan 3 and this stagnation region and noise due to the secondary flow are generated, so that noise caused by the tongue 16 is generated together with the above-described vortex noise. .

  Therefore, first, the counterclockwise direction of the fan 3 (counterclockwise in FIG. 4) is directed to the second end wall 22 side (the other end side in the axial direction of the rotating shaft 7) of the tongue 16 toward the second end wall 22 side. An attempt was made to form the first overhanging portion 16A inclined so as to increase the size of the overhanging direction). And the specific noise at the time of changing the shape of this 1st overhang | projection part 16A was measured. In changing the shape, as shown in FIG. 5, the dimension of the tongue 16 in the axial direction of the rotating shaft 7 is H (that is, the overall dimension of the tongue 16 in the axial direction of the rotating shaft 7). The dimension in the axial direction of the rotary shaft 7 from the end portion P1 on the second end wall 22 side (the other axial end side of the rotary shaft 7) to the point P2 at which the second end wall 22 starts to project is Z1 (that is, the first 1 dimension of the overhang portion 16A in the axial direction of the rotary shaft 7).

  The change in the specific noise when the ratio Z1 / H of the dimension Z1 in the axial direction of the rotary shaft 7 of the first overhanging portion 16A with respect to the overall dimension H in the axial direction of the rotary shaft 7 of the tongue portion 16 is changed. Measured. The result is shown in FIG. By forming the first overhanging portion 16A, the stagnation region (100B in FIG. 8) at the corner on the electric motor 2 side indicated by LWR in FIG. 9 disappears, so that the specific noise is compared with the case where Z1 / H = 0. However, it is particularly good in the range of 0.2 to 0.6 (0.2 ≦ Z1 / H ≦ 0.6), and the specific noise is the smallest when Z1 / H = 0.4. It was found to be −0.8 dB. Therefore, in the present invention, Z1 / H is set to 0.4.

  Next, without forming the first overhanging portion 16A, the portion on the first end wall 21 side (one axial end side of the rotating shaft 7) of the tongue portion 16 is directed toward the first end wall 21 side. An attempt was made to form the second overhanging portion 16B inclined so that the dimension of the fan 3 protruding in the counter-rotating direction (counterclockwise direction in FIG. 4) increases. And the specific noise at the time of changing the shape of this 2nd overhang | projection part 16B similarly was measured. In addition, when changing the shape, as shown in FIG. 5, the protruding portion starts from the end P <b> 1 on the second end wall 22 side (the other end side in the axial direction of the rotating shaft 7) of the tongue 16 on the first end wall 21 side. The dimension in the axial direction of the rotating shaft 7 up to P3 was defined as Z2 (that is, the overall dimension in the axial direction of the rotating shaft 7 of the tongue portion 16−the dimension in the axial direction of the rotating shaft 7 of the second overhanging portion 16B).

  And Z2 with respect to the overall dimension H in the axial direction of the rotary shaft 7 of the tongue 16 (the overall dimension in the axial direction of the rotary shaft 7 of the tongue 16-the dimension in the axial direction of the rotary shaft 7 of the second overhanging portion 16B). The change in the specific noise when the ratio Z2 / H was changed was measured. The result is shown in FIG. By forming the second overhanging portion 16B, the stagnation region (100A in FIG. 8) at the corner on the suction port 11 side indicated by UPR in FIG. 9 disappears, so that the specific noise is compared with the case of Z2 / H = 1. However, it is particularly good in the range of 0.4 to 0.9 (0.4 ≦ Z2 / H ≦ 0.9), and the specific noise is the smallest when Z2 / H = 0.6. It was found to be −0.65 dB. Therefore, in the present invention, Z2 / H is set to 0.6.

  And both the said 1st overhang | projection part 16A and the 2nd overhang | projection part 16B were formed in the tongue part 16 like the Example shown in FIG. 5, and those dimensional ratios Z1 / H and Z2 / H were changed. The amount of reduction in specific noise in this case is shown in FIG. As is clear from this figure, when the dimensional ratios Z1 / H and Z2 / H are the most favorable values, that is, Z1 / H = 0.4 and Z2 / H = 0.6, It was found that the specific noise reduction amount was −1.20 dB, which was the largest reduction amount.

  This is because both the stagnation regions 100A and 100B shown in FIG. 8 have disappeared as shown in FIG. 9 due to the formation of the first and second overhang portions 16A and 16B. Further, by forming both the first overhanging portion 16A and the second overhanging portion 16B as compared with the case where the blade as shown in FIG. 10 extends in parallel with the rotating shaft of the electric motor, this tongue The shape of the portion 16 is more in line with the velocity distribution of the air flowing out from the fan 3. As a result, the noise in the tongue 16 having such a shape as compared with a fan in which the blade extends in parallel with the rotating shaft of the electric motor (similar measurement, the reduction amount of the specific noise was -0.52 dB). Is considered to be more effectively reduced.

  Note that the end portion P1 of the tongue portion 16 shown in FIG. 5, the end portion on the suction port 11 side (indicated by P4), and the points P2 and P3 at which the overhang portions 16A and 16B start to stick are obtuse angles, but the corner portions. Become. Therefore, there is a concern that turbulence will occur when air collides with this corner, but if the corners formed at these points P1 to P4 are smoothly curved and connected, they will occur when the air collides with them. Disturbance can be suppressed and further noise reduction can be realized.

(Shape of standing wall 26 and bell mouth 27)
Next, the shape of the upright wall 26 and the bell mouth 27 of the scroll casing 4 according to the embodiment will be described with reference to FIGS. The inventor verified whether or not noise due to air flowing into the fan 3 could be reduced by the shape of the standing wall 26 and the bell mouth 27. FIG. 12 is an enlarged vertical side view of the inlet 11 portion of the scroll casing 4, and FIGS. 13 to 15 show the verification results. 16 to 18 are schematic diagrams for explaining the verification results.

  As described above, in the case of a fan in which the blade extends in parallel with the rotating shaft of the electric motor, the flow of air flowing from the suction port inside the bell mouth due to the rotation of the fan is caused by the base side of the blade (the bottom plate with the electric motor). Side) and concentrate. In the case of a normal bell mouth as shown in FIG. 16, almost no inflow to the blade 106 occurs due to separation at the tip of the bell mouth 103 on the suction port 102 side of the blade 106, and the blade 106 is in a stagnation state. Therefore, the air flow concentrated on the base side of the blade 106 has a locally high flow velocity distribution, leading to an increase in noise proportional to the sixth power of the air flow velocity.

  Therefore, in the fan 3 as in the present invention, first, the standing wall 26 as in the embodiment was formed around the suction port 11, and the height dimension L was changed to measure the specific noise and the fan efficiency. FIG. 13 shows the results. Here, L is a dimension in which the standing wall 26 rises from the first end wall 21, D is a diameter of the fan 3 (a dimension of a line passing between the outer ends of the blades 8 through the axial center of the boss portion 6B), Changes in specific noise and fan efficiency were measured when the ratio L / D of the standing dimension L of the standing wall 26 to the fan diameter D (maximum diameter) was changed.

  As is clear from FIG. 13, it was found that when L / D is in the range of 0 to 0.3, specific noise decreases and fan efficiency improves as L / D increases. In particular, the specific noise had a reduction effect of -2.3 dB in the measurement range. This is because the upright wall 26 is high, and the curved vertical dimension of the bell mouth 27 is increased, and the air flowing in from the suction port 11 flows along the bell mouth 27 by the Coanda effect, and the blade of the fan 3 as shown in FIG. As compared with the fan 104 in which the blade 106 as shown in FIG. 18 extends in parallel with the rotating shaft of the electric motor. The inlet angle at the inlet (inner end) of the blade 8 more closely matches the inflow angle of the air sucked from the suction port 11 and flowing into the blade 8 (the direction when the air flows into the blade 8 and the extension of the blade 8) This is presumably because the direction is closer to the right angle than the blade 106 of FIG. 18 indicated by a broken line in FIG.

  That is, it is considered that the air flow rate is made uniform between the blades 8 in the longitudinal direction of the blades 8 (the axial direction of the rotary shaft 7), the portion where the high speed is locally eliminated, and the noise is reduced. . However, even if it is better to have a larger L / D, if the standing dimension L of the standing wall 26 is too large, it will lead to an increase in the dimension of the centrifugal blower 1 itself, so there is naturally a limit.

  Thus, although it turned out that the bellmouth 27 when the standing wall 26 is formed upright is effective, the shape of the bellmouth 27 itself was also verified. Factors in this case include a dimension (inner dimension of the fan 3) Rf1 from the axis center of the rotating shaft 7 to the inner end of the blade 8, and a bell mouth 27 (the suction port 11 of the upright wall 26) from the axis center of the rotating shaft 7. Side surface) to the tip (end of the fan 3 side) (inner dimension of the tip of the bell mouth 27) R1 and the dimension from the center of the rotation shaft 7 to the inner end of the bell mouth 27 (the bell mouth 27). Minimum internal dimension) R2 was adopted.

  First, specific noise and fan efficiency were measured when the ratio R1 / Rf1 of the inner dimension R1 of the tip of the bell mouth 27 to the inner dimension Rf1 of the fan 3 was changed. The result is shown in FIG. In this figure, the vertical line of R1 / Rf1 = 1.13 indicated by a bold line indicates the limit point due to the minimum gap dimension with the rim 9. If R1 is further increased, the bell mouth 27 and the rim 9 Must be set below this value.

  As is clear from this figure, the specific noise is reduced most at R1 / Rf1 = 1.06, and the fan efficiency is highest at R1 / Rf1 = 1.06, both of which deteriorate before and after. It becomes a trend. This is considered to be because when R1 becomes larger than Rf1, the amount of air flowing along the bell mouth 27 leaks to the outside of the rim 9 from the gap between the tip of the bell mouth 27 and the blade 8. It is done. Therefore, it can be seen that it is preferable to set R1 / Rf1 within a range of 1 to 1.1 (1 ≦ R1 / Rf1 ≦ 1.1) that does not deteriorate greatly, and in the embodiment, noise and fan efficiency are the best. R1 / Rf1 = 1.06 was set.

  Next, specific noise and fan efficiency were measured when the ratio R2 / R1 of the minimum inner dimension R2 of the bell mouth 27 to the inner dimension R1 of the tip of the bell mouth 27 was changed. The result is shown in FIG. From this figure, when R2 / R1 is in the range of 0.9 to 1.02, the specific noise R2 / R1 = 0.98 is the most reduced, and the fan efficiency is highest at R2 / R1 = 0.95. After that, both tend to get worse. Therefore, it can be seen that R2 / R1 may be set in a range of 0.94 to 1 (0.94 ≦ R2 / R1 ≦ 1).

  Therefore, in the embodiment, R2 / R1 = 0.98 is set when emphasizing noise reduction, and R2 / R1 = 0.95 is set when emphasizing fan efficiency. This is because the shape of the fan 3 makes it easier for air to enter the suction port 11 side of the blade 8, so that it is better to have the air wrap around the rim 9 along the bell mouth 27. Conceivable.

(Shape of scroll casing 4)
Here, when a fan whose blade extends parallel to the rotating shaft of the electric motor is housed in a normal scroll casing, the air flowing in from the bell mouth of the suction port flows toward the bottom plate of the fan blade and concentrates. Therefore, the flow rate of the air flowing out from the fan tends to be higher on the bottom plate side than on the rim side. However, the flow velocity of the air flowing out of the fan has a component in the circumferential direction and a component in the radial direction, and the component in the circumferential direction tends to be high on the rim side and low on the bottom plate side. The radial component is higher on the bottom plate side and lower on the rim side. From such a situation, a secondary flow from the bottom plate side toward the rim side along the outer peripheral wall of the scroll casing is generated in the spiral flow path in the scroll casing, and noise increases and efficiency decreases. Become.

  On the other hand, in the case of the fan 3 according to the present invention in which the inner diameter is gradually decreased toward the bottom plate 6 side as shown in FIG. 19, the velocity distribution of the air flowing out from the fan 3 is made uniform between the rim 9 and the bottom plate 6 side. Is done. This has the effect of reducing noise as described above, but the air speed on the rim 9 side is higher than that of the fan 104 as shown in FIG.

  Smoothly reducing the increased air flow leads to further noise reduction, but the height in the axial direction of the rotating shaft 7 is from the beginning of the spiral flow path 19 to the outlet 12 as in the embodiment. If the scroll casing 4 gradually enlarged toward the rim is used, the speed of the air flowing out from the rim 9 side of the fan 3 is discharged into the spiral channel 19 in the scroll casing 4 using the enlarged space. , Will come down smoothly. Thereby, the effect of noise reduction by enlarging the height in the axial direction of the rotating shaft 7 of the scroll casing 4 can be further enjoyed.

  As a result of the measurement, when the fan 104 as shown in FIG. 16 is housed in the scroll casing 4 of the present invention, the reduction amount of the specific noise is −1.0 dB, compared with the fan 3 and the scroll as in the present invention. In the case of the casing 4, the effect was further improved to -1.8 dB.

  With the configuration described above in detail, the specific noise is 2 by the upright wall 26 and the bell mouth 27 of the embodiment as compared with the specific noise when the fan 3 according to the present invention is housed in a normal scroll casing (FIGS. 8 and 16). .26 dB decrease. Further, in addition to this, when the height of the first end wall 21 in the axial direction of the rotating shaft 7 is gradually increased from the winding start of the spiral channel 19 toward the outlet 12, in the case of a normal scroll casing The specific noise decreased by 4.09 dB. Furthermore, in addition to them, it was confirmed that when the shape of the tongue portion 16 was the same as that of the above embodiment, the specific noise was reduced by 4.95 dB compared to the case of the normal scroll casing.

  On the other hand, in the case of the fan 104 as shown in FIG. 16, the noise reduction value is 1.92 dB for the standing wall and the bell mouth, 2.89 dB when the first end wall 21 is enlarged, and the shape of the tongue 16 is changed. When further added, it was 3.13 dB. That is, it is clear that a great noise reduction effect is exhibited by using the fan 3 as in the present invention whose inner diameter becomes smaller toward the bottom plate 6 side and designing the structure of the scroll casing 4 as in the present invention. became.

DESCRIPTION OF SYMBOLS 1 Centrifugal blower 2 Electric motor 3 Fan 4 Scroll casing 6 Bottom plate 7 Rotating shaft 8 Blade 9 Rim 11 Suction port 12 Air outlet 16 Tongue part 16A First overhang part 16B Second overhang part 19 Spiral flow path 21 1st End wall 22 Second end wall 26 Standing wall 27 Bellmouth

Claims (10)

A bottom plate fixed to the rotating shaft, a plurality of blades whose bases are fixed to the outer periphery of the bottom plate, and an annular rim that is provided coaxially with the bottom plate and connects the tip portions of the blades. A fan whose inner diameter becomes smaller toward the bottom plate side,
A scroll casing that houses the fan and has a suction port on one axial end side of the rotating shaft;
A spiral flow path configured around the fan in the scroll casing;
A tongue that suppresses inflow of air from the winding end to the winding start of the spiral flow path,
Portion of the other axial end of the rotary shaft of the tongue, the dimensions overhanging reverse rotation direction of the fan is inclined so as to increase toward the other axial end of the rotary shaft, wherein the tongue When the dimension in the axial direction of the rotating shaft of the rotating shaft is H, and the dimension in the axial direction of the rotating shaft from the end of the tongue portion on the other end side in the axial direction of the rotating shaft to Z
0.2 ≦ Z1 / H ≦ 0.6
Centrifugal blower characterized by being said. The centrifugal blower according to claim 1, wherein Z1 / H = 0.4. A portion of the tongue portion on one end side in the axial direction of the rotating shaft is also inclined so that the dimension of the tongue projecting in the counter-rotating direction increases toward the one end side in the axial direction of the rotating shaft. The centrifugal blower according to claim 1 or 2. The dimension of the tongue portion in the axial direction of the rotating shaft is H, and from the end portion of the tongue portion on the other end side in the axial direction of the rotating shaft to the point at which the tongue portion starts to project on one end side in the axial direction of the rotating shaft. When the dimension in the axial direction of the rotating shaft is Z2,
0.4 ≦ Z2 / H ≦ 0.9
The centrifugal blower according to claim 3, wherein The centrifugal blower according to claim 4, wherein Z2 / H = 0.6. The centrifugal blower according to any one of claims 1 to 5, wherein an end portion of the tongue portion and a corner portion at a point where overhanging starts to be smoothly curved. A standing wall is formed in the scroll casing around the suction port, and the surface of the standing wall on the suction port side is curved like a bell mouth,
The dimension from the axial center of the rotating shaft to the inner end of the blade is Rf1, the dimension from the axial center of the rotating shaft to the tip of the surface on the suction port side of the standing wall is R1, and from the axial center of the rotating shaft When the dimension to the inner end of the surface on the suction port side of the standing wall is R2,
1 ≦ R1 / Rf1 ≦ 1.1,
and,
0.94 ≦ R2 / R1 ≦ 1
The centrifugal blower according to any one of claims 1 to 6, wherein the centrifugal blower is provided. R1 / Rf1 = 1.06 and R2 / R1 = 0.98,
Or
R1 / Rf1 = 1.06 and R2 / R1 = 0.95
The centrifugal blower according to claim 7, wherein A bottom plate fixed to the rotating shaft, a plurality of blades whose bases are fixed to the outer periphery of the bottom plate, and an annular rim that is provided coaxially with the bottom plate and connects the tip portions of the blades. A fan whose inner diameter becomes smaller toward the bottom plate side,
A scroll casing that houses the fan and has a suction port on one axial end side of the rotating shaft;
A spiral flow path configured around the fan in the scroll casing,
A standing wall is formed in the scroll casing around the suction port, and the surface of the standing wall on the suction port side is curved like a bell mouth,
The dimension from the axial center of the rotating shaft to the inner end of the blade is Rf1, the dimension from the axial center of the rotating shaft to the tip of the surface on the suction port side of the standing wall is R1, and from the axial center of the rotating shaft When the dimension to the inner end of the surface on the suction port side of the standing wall is R2,
R1 / Rf1 = 1.06 and R2 / R1 = 0.98,
Or
R1 / Rf1 = 1.06 and R2 / R1 = 0.95
A centrifugal blower characterized by that. A blower outlet located downstream of the end of winding of the spiral flow path;
The height in the axial direction of the rotating shaft of the scroll casing gradually increases from the beginning of winding of the spiral channel toward the outlet. The centrifugal blower described in the crab.

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