JP2008232049A - Centrifugal impeller and centrifugal blower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal impeller in which a direction of a blade front edge and an air inflow direction are less different from each other and its manufacturing method is easy and further an air sending capability can be improved. <P>SOLUTION: There is provided a centrifugal impeller 1 characterized in that a blade center line 9 of a blade cross-section 8 of an arbitrary plane perpendicular to a rotational shaft 3 is convex relatively to a rotational direction and a blade 7 is upright in a direction of the rotational shaft 3 and besides with respect to an inlet blade angle, a main plate 2 side is smaller than a shroud 6 side. In the centrifugal impeller 1, a manufacturing method of the blade is easy. Then, the inlet blade angle and an air inflow angle are made less different from each other to restrain exfoliation of the blade front edge 15, thereby allowing a centrifugal impeller 1 capable of improving the air sending capability to be acquired. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a centrifugal impeller and a centrifugal blower used for, for example, an air-conditioning blower or a ventilation blower.

  Conventionally, this type of centrifugal impeller includes a disk-shaped main plate having a rotation shaft at the center, and a donut-shaped shroud disposed so as to face the main plate with an air passage interval around the rotation shaft, There has been known one provided with a plurality of blades sandwiched between the main plate and the shroud and arranged in an annular shape (for example, see Patent Document 1).

  Hereinafter, the centrifugal impeller will be described with reference to FIG.

  As shown in the figure, the centrifugal impeller 101 is spaced apart in the circumferential direction between a main plate 102 to be rotated, an annular shroud 106 provided at a position facing the main plate 102, and the main plate 102 and the shroud 106. The front edge 104 which is provided open and is an end portion on the inner peripheral side is composed of a plurality of blades 103 inclined toward the rotation direction side.

In the above configuration, when the centrifugal impeller 101 rotates, air is sucked by the centrifugal impeller 101 through the bell mouth 109 and then sent out to the outer peripheral side of the centrifugal impeller 101. At this time, the position of the joining end portion on the shroud 106 side with respect to the joining end portion on the main plate 102 side of the blade 103 is shifted and offset from the front edge 104 to the rear edge 105 in the rotational direction side, thereby leading to the leading edge 104. Since the end on the side of the shroud 106 is inclined toward the rotation direction, it is possible to suppress separation on the rear side in the rotation direction that occurs during rotation.
Japanese Patent Laid-Open No. 2003-206872

  In such a conventional centrifugal impeller, there is a problem that air blowing performance is deteriorated because separation occurs when there is a difference between the direction of the leading edge of the blade and the inflow direction of air.

  Furthermore, in the centrifugal impeller shown in Patent Document 1, it is possible to suppress separation that occurs during rotation, but the position of the joining end portion with the shroud 106 side is smaller than the joining end portion with the main plate 102 side of the blade. Since the front edge 104 and the rear edge 105 are shifted and offset in the rotational direction, there is a problem that the manufacture is difficult, and it is required to improve the blowing performance without requiring a difficult manufacture. .

  The present invention solves such a conventional problem, and there is little difference between the direction of the leading edge of the blade and the inflow direction of the air, that is, the air flow does not separate from the blade, and the manufacturing method is It is an object to provide a centrifugal impeller that is easy and can improve the blowing performance.

  In order to achieve the above object, the centrifugal impeller of the present invention has a disk-shaped main plate having a rotation shaft at the center, and a donut-like shape arranged so as to be opposed to the main plate with an air passage interval around the rotation shaft. A centrifugal blade having a shroud, a plurality of blades sandwiched between a main plate and a shroud and arranged in an annular shape, and having a blade center line in a cross section of an arbitrary plane perpendicular to the rotation axis convex to the rotation direction In the car, the blade entrance angle formed by the intersection of the blade curved surface and the arbitrary cylindrical surface centering on the rotation axis is parallel to the rotation axis, and the tangent line between the rotation direction side circumferential tangent of the blade leading edge and the blade center line is The centrifugal impeller is characterized in that the main plate side is smaller than the shroud side.

  The flow sucked by the rotation of the impeller has an air inflow angle formed by an air inflow direction component on a plane perpendicular to the rotation axis and a circumferential tangent on the rotation direction side, and reaches the blade leading edge. At the blade leading edge, the closer to the main plate, the smaller the air volume and the greater the radial speed, so the air inlet angle on the main plate tends to be smaller than the air inlet angle on the shroud side. Therefore, by this means, since the difference between the blade inlet angle and the air inflow angle is reduced, the flow can be smoothly taken in from the blade leading edge, and the performance is improved. Further, since the blade has a simple shape curved only in the rotation direction, the manufacturing method is easy.

  Another means is a centrifugal impeller characterized in that the trailing edge of the blade is parallel to the rotation axis.

  By this means, when compared with the same blade outer diameter, the surface area of the blade is maximized, and more air can be sent to the outer peripheral side of the centrifugal impeller.

  Another means is a centrifugal impeller having a blade whose difference between the blade inlet angle on the shroud side and the blade inlet angle on the main plate side is more than 0 ° and not more than 15 °.

  By this means, an effective blade inlet angle can be set with respect to the air inflow angle, and the air blowing performance can be improved. Moreover, since the joint part of a braid | blade and a main board can be lengthened as much as possible, the intensity | strength which resists the centrifugal force by rotation can be maintained.

  Another means is a centrifugal impeller characterized in that the blade inlet angle is equal to the air inflow angle at an arbitrary blade cross section.

  By this means, separation / collision due to the difference between the air inlet angle and the blade inlet angle can be mitigated by making the blade inlet angle equal to the air inlet angle, thereby improving the blowing performance.

  Another means is a development view in the circumferential direction of a blade expanded so that the center line of an arbitrary blade cross section is a straight line, and the centrifugal impeller is characterized in that the leading edge is a straight line. is there.

  By this means, the blade inlet angle can be reduced as it approaches the main plate side from the shroud side, and the rate of reduction can be changed by adjusting the inclination. Thus, an effective blade entrance angle can be set.

  Another means is a centrifugal impeller characterized in that the blade inner diameter on the main plate side suddenly expands with an arbitrary blade cross section as a boundary.

  By this means, it is possible to prevent a change in flow caused by an obstacle that may exist in the center of the main plate from adversely affecting the blade.

  Another means is a centrifugal impeller characterized in that the inner diameter of the shroud is not more than the inner diameter of the blade.

  By this means, it is possible to suppress the performance from being deteriorated because the sucked flow collides with the blade.

  Another means is a centrifugal impeller having a blade whose arbitrary blade cross-sectional shape is an airfoil.

  By this means, the flow can be sent out more smoothly to the outer peripheral side of the centrifugal impeller, and the performance is improved.

  Another means is a centrifugal impeller characterized by an arbitrary blade cross-sectional shape and a large front edge.

  By this means, it is possible to suppress the occurrence of peeling due to the change in the air flow rate and the change in the air inflow angle depending on the use state of the centrifugal impeller.

  Another means is a centrifugal blower including a centrifugal impeller and a scroll casing that guides the discharge flow of the centrifugal impeller to the discharge port in a spiral shape.

  By this means, the discharge flow sent to the outer peripheral side of the centrifugal impeller by the rotation of the centrifugal impeller can be efficiently guided to the discharge port by the scroll casing.

  According to the present invention, there is little difference between the direction of the leading edge of the blade and the inflow direction of the air, that is, the air flow is not separated from the blade, the manufacturing method is easy, and the blowing performance can be improved. Can be provided.

  The invention according to claim 1 of the present invention includes a disc-shaped main plate having a rotation shaft at the center thereof, a donut-shaped shroud disposed so as to face the main plate with the air passage spacing around the rotation shaft, and the main plate A centrifugal impeller having a plurality of blades sandwiched between a blade and a shroud and arranged in an annular shape, and having a blade centerline in a cross section of an arbitrary plane perpendicular to the rotation axis having a convex shape with respect to the rotation direction. The intersecting line between the curved surface and any cylindrical surface centering on the rotation axis is parallel to the rotation axis, and the blade entrance angle formed by the tangent line between the rotation direction side circumferential tangent of the blade leading edge and the blade center line is larger than the shroud side. It is a centrifugal impeller characterized by a small main plate side, and the blade inlet angle has the same property as the tendency of the air inlet angle on the main plate side to be smaller than the air inlet angle on the shroud side, so the flow is smooth Blur It can be incorporated from de front edge, without causing peeling from the blade of the airflow has the effect of improving performance. Further, since the blade has a simple shape curved only in the rotation direction, it has an effect that it can be easily manufactured.

  In addition, the centrifugal impeller is characterized in that the trailing edge of the blade is parallel to the rotation axis. When compared with the same blade outer diameter, the blade surface area is maximized, and more air is supplied to the centrifugal blade. It has the effect | action that it can send out to the vehicle outer peripheral side.

  In addition, the centrifugal impeller has a blade in which the difference between the blade inlet angle on the shroud side and the blade inlet angle on the main plate side is greater than 0 ° and not more than 15 °. It can set, and has the effect | action that a ventilation performance can be improved. Moreover, since the joint part of a braid | blade and a main board can be lengthened as much as possible, it has the effect | action that the intensity | strength which resists the centrifugal force by rotation can be maintained.

  In addition, the centrifugal impeller is characterized in that the blade inlet angle is equal to the air inlet angle at any blade cross section, and the blade inlet angle is determined by the separation and collision caused by the difference between the air inlet angle and the blade inlet angle. It can be mitigated by making it equal to the air inflow angle, and has the effect of improving the blowing performance.

  Further, the blade is expanded in the circumferential direction so that the center line of the arbitrary blade cross section becomes a straight line, and is a centrifugal impeller characterized in that the leading edge is a straight line. The blade inlet angle can be reduced as it approaches the main plate side, and the rate of reduction can be changed by adjusting the slope, so that the effective blade inlet for various air inflow angle trends. It has an effect that a corner can be set.

  In addition, it is a centrifugal impeller characterized by a sudden expansion of the inner diameter of the blade on the main plate side at any blade cross-section, preventing changes in flow caused by obstacles from adversely affecting the blade. Has the effect of being able to

  In addition, the centrifugal impeller is characterized in that the inner diameter of the shroud is equal to or less than the inner diameter of the blade, and has an effect that it is possible to suppress deterioration in performance because the sucked flow collides with the blade.

  In addition, it is a centrifugal impeller having a blade whose shape of an arbitrary blade cross section is an airfoil, and can flow smoothly to the outer peripheral side of the centrifugal impeller, and has an effect of improving performance. .

  In addition, it is a centrifugal impeller characterized by an arbitrary blade cross-sectional shape and a large leading edge, and the air flow rate changes depending on the use state of the centrifugal impeller, and the air inflow angle changes. It has the effect of preventing the occurrence of peeling due to.

  Further, the centrifugal impeller and the centrifugal blower provided with a scroll casing for guiding the discharge flow of the centrifugal impeller to the discharge port in a spiral shape, and the discharge flow sent to the outer peripheral side of the centrifugal impeller by the rotation of the centrifugal impeller Can be efficiently guided to the discharge port by the scroll casing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a plan view and a side view of a centrifugal impeller in Embodiment 1 of the present invention.

  In FIG. 1, a centrifugal impeller 1 of the present invention is opposed to a disk-shaped main plate 2 having a diameter of 257 mm and a thickness of 3 mm having a rotation shaft 3 at the center, and the main plate 2 through the air passage 4 with the rotation shaft 3 as the center. A donut-shaped shroud 6 having a suction port 5 with an outer diameter of 257 mm, an inner diameter of 142 mm, and a thickness of 2 mm, and a plate of 2 mm thickness between the main plate 2 and the shroud 6, and seven annularly spaced at regular intervals And a blade 7 sandwiched between the two. The airway outlet interval H is 82 mm. The blade 7 has a shape in which a blade center line 9 of a blade cross section 8 formed by an arbitrary plane perpendicular to the rotation shaft 3 is convex with respect to the rotation direction 10. FIG. 2 shows a detailed view of the blade shape. From FIG. 2, the rotation direction side blade intersection line 12 and the reverse rotation direction side blade intersection line 13, which are intersection lines between an arbitrary cylindrical surface 11 centering on the rotation axis 3 and the blade 7, are parallel to the rotation axis 3. The blade 7 has a shape standing upright in the direction of the rotary shaft 3.

  At this time, the shroud joint blade inner diameter Dbi1 at the joint portion with the shroud 6 is 142 mm, the main plate joint portion blade inner diameter Dbi2 at the joint portion with the main plate 2 is 150 mm, and the blade inner diameter is larger toward the main plate 2 side. The inner diameter of the blade is larger than the inner diameter of the shroud. The blade outer diameter Dbo is 229 mm, and the blade trailing edge 14 is parallel to the rotating shaft 3. Here, FIG. 3 shows a detailed view of the blade inlet angle. In FIG. 3, the blade entrance angle formed by the blade front edge 15 and the circumferential tangent line 16 on the rotational direction 10 side and the blade center line tangent line 17 is α1 = 16 ° on the shroud 6 side, and α2 = 12 ° on the main plate 2 side. The relationship of α1> α2 is established. The difference Δα between α1 and α2 is 4 °.

  Here, the manufacturing process of the blade is shown in FIG. 4 (a) and 4 (b), the blade 7 cuts the material into a rectangular plate 18, and the front edge side 19 to be the blade leading edge 15 is connected to the main plate 2 side from the shroud side 20 connected to the shroud 6. The main plate edge 21 to be connected is cut as a front edge cutting line 22 and the shroud edge 20 is cut as indicated by 23 along the shape of the shroud 6. In FIG. It is manufactured by bending 9 in only one direction so that 9 is a convex arc with respect to the rotation direction 10.

  FIG. 5 shows a detailed view of the air inflow angle. In FIG. 5, an angle formed by the air inflow speed 24 and the circumferential tangent line 16 is defined as an air inflow angle γ. The air inflow velocity 24 has a radial inflow velocity component 25. The air sucked by the rotation of the centrifugal impeller 1 is guided to the shroud 6 side as the air outside the suction port 5 and toward the main plate 2 side as the air closer to the center of the suction port 5, so that the air reaches the main plate 2 side. Hateful. Therefore, since the air flow rate on the main plate 2 side is smaller at the blade leading edge 15 than at the shroud 6 side, the radial inflow velocity component 25 is smaller at the main plate 2 side than at the shroud 6 side. The 2 side is smaller.

  In the above configuration, when the centrifugal impeller 1 rotates around the rotation shaft 3, the centrifugal impeller 1 is sucked in through the air inlet 4 by the pressure increasing action caused by the rotation of the blade 7 of the centrifugal impeller 1 and passes through the air passage 4. It is discharged to the outer peripheral side.

  At this time, there is a relationship of α1> α2 at the shroud side blade inlet angle α1 and the main plate side blade inlet angle α2, and the air inflow angle γ is smaller on the main plate 2 side than on the shroud 6 side. There is little difference from the angle γ, separation at the blade leading edge 15 can be suppressed, and the flow can be smoothly taken from the blade leading edge 15 to improve the blowing performance.

  Since the blade 7 is manufactured by cutting each side of the rectangular plate 18 of material and bending it in only one direction, the blade 7 is easy to manufacture, and an easy process of cutting the side that becomes the blade leading edge 15 is performed. Only the blade inlet angle can be adjusted. The outline of the blade 7 shown in FIG. 1 has a meridional shape that is a projection view of the rotation direction 10, and in order for the blade leading edge 15 to be a straight line in the meridional shape as shown in FIG. The front edge 19 serving as the front edge needs to be curved like a front edge cutting line 22. The processing of the front edge 19 varies depending on the tendency of the air inflow angle γ, but the same effect can be obtained by a simple process of cutting along the front edge 1 straight line 26.

  Further, since the blade trailing edge 14 is parallel to the rotary shaft 3, the maximum blade surface area is taken. Therefore, since the work amount per blade 7 is large, the air blowing performance is improved.

  Further, the difference in the air inflow angle γ between the shroud 6 side and the main plate 2 side varies depending on the size and use state of the centrifugal impeller 1, and the difference is larger than 0 ° and not more than 15 ° in a general centrifugal impeller. is there. Therefore, by setting the blade inlet angle difference Δα within this range, an effective blade inlet angle can be set with respect to the air inflow angle γ, and the performance can be improved. Further, if the main plate side blade inlet angle α2 is decreased to increase the blade inlet angle difference Δα, the length of the joint portion between the blade 7 and the main plate 2 is shortened. Therefore, since the length of the joint portion between the blade 7 and the main plate 2 can be made as long as possible by suppressing the difference Δα in the blade entrance angle to 15 ° or less, the strength that can withstand centrifugal force due to rotation can be maintained. .

  Further, the air blowing performance is further improved by making the blade inlet angle equal to the air inflow angle γ.

  The inner diameter of the shroud 6 is 142 mm, the shroud joint blade inner diameter Dbi 1 is 142 mm, the main plate joint section blade inner diameter Dbi 2 is 150 mm, and the blade inner diameter is larger than the inner diameter of the shroud 6. A decrease in performance due to a collision can be suppressed.

  Further, by making the shape of the blade cross section 8 into an airfoil like the blade cross section 8 shown in FIG. 6, the flow can be more smoothly sent to the outer peripheral side of the centrifugal impeller 1 and further improvement of the air blowing performance is expected. it can. When the dimension of the airfoil is an arc length L1, the maximum thickness T is preferably 0.04 to 0.05 arc length L1, and the maximum thickness position Xt is 0.3 to 0.5 arc length L1 from the front edge. Is desirable.

  Further, as shown in FIG. 7A, when the blade leading edge 15 is bent to the opposite side of the rotational direction 10 to increase the thickness of the blade leading edge 15 in the blade transverse section 8, as shown in FIG. Generation | occurrence | production of peeling by the air inflow angle (gamma) changing with the use conditions of 1 can be suppressed, and the ventilation performance improvement can be anticipated further. The thickness increase dimension Δt is preferably 0.01 to 0.05 chord length L2, and the thickness increase width M is preferably 0.02 to 0.1 chord length L2 with respect to the chord length L2. Furthermore, it is preferable that the shape is a smooth curve. It should be noted that the same effect can be obtained by increasing the thickness on the rotational direction side as shown in FIG. 7 (b) or increasing the thickness on both sides as shown in FIG. 7 (c).

(Embodiment 2)
The same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 8 is a plan view and a side view of the centrifugal impeller in Embodiment 2 of the present invention. 8, the centrifugal impeller 1 of the present invention includes a disk-shaped main plate 2 having a diameter of 257 mm and a thickness of 3 mm, a cylindrical shape having a diameter of 60 mm and a height of 5 mm at the center of the main plate 2, and the motor rotating shaft 27 and the main plate 2. It has the structure which has the boss | hub 28 for connecting.

  FIG. 9 shows a manufacturing process of the blade 7 in the present invention. In FIG. 9A, the blade 7 cuts the material into a rectangular plate 18, cuts the front edge side 19 which becomes the blade leading edge 15 by the straight line a29 and the straight line b30, and shrouds the shroud side 20 which becomes the shroud 6 side. 6 is cut along the shroud side cutting line 23 so as to be curved in only one direction so that the blade center line 9 becomes a convex arc with respect to the rotation direction 10 in FIG. And the inner diameter of the blade suddenly expands at the blade leading edge 15. The rapid expansion means that the inner diameter is enlarged to such an extent that a change in flow by the boss 28 does not affect the blade 7, and the inner diameter is enlarged by about 20 to 30% of the diameter of the boss 28.

  In the above configuration, when the centrifugal impeller 1 rotates around the rotation shaft 3, the centrifugal impeller 1 is sucked in through the air inlet 4 by the pressure increasing action caused by the rotation of the blade 7 of the centrifugal impeller 1 and passes through the air passage 4. It is discharged to the outer peripheral side. At this time, when the sucked flow reaches the boss 28, the flow changes along the shape of the boss 28.

  At this time, a boss 28 for connecting the rotary shaft 3 and the main plate 2 exists in the center of the main plate 2, and the flow that reaches the vicinity changes along its shape, and the change in the flow field reaches the blade leading edge 15. If it reaches, there is a possibility that the air blowing performance is lowered. Therefore, by rapidly expanding the inner diameter of the blade, it is possible to prevent a change in flow caused by the boss 28 from adversely affecting the blade 7. It should be noted that the processing shape of the leading edge 19 that becomes the blade leading edge 15 is desirably an appropriate shape depending on the flow state changed depending on the shape and dimensions of the boss 28, and is a combination of a plurality of straight lines and curves. Also good.

(Embodiment 3)
The same parts as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 10 is a perspective view of a centrifugal fan according to Embodiment 3 of the present invention. In FIG. 10, the centrifugal blower 31 of the present invention includes an outer frame surrounding the centrifugal impeller 1, an outer frame suction port 32 centering on the rotation shaft 3, and a front plate 33 covering the shroud 6 side and a main plate 2 side. A back plate 34 to cover, a scroll plate 35 covering the outer peripheral side of the centrifugal impeller 1, a front plate edge 36 of the front plate 33, a back plate edge 37 of the back plate 34, and a scroll plate edge 38 of the scroll plate 35. It is the structure provided with the spiral scroll casing 40 formed from the discharge port 39 comprised by this.

  In the above-described configuration, when the centrifugal impeller 1 rotates around the rotation shaft 3, air is sucked from the outer frame suction port 32 by the pressure increasing action caused by the rotation of the blade 7 of the centrifugal impeller 1, and the outer periphery of the centrifugal impeller 1. The air discharged to the side is guided to the discharge port 39 by the scroll casing 40.

  At this time, since the air sent to the outer peripheral side of the centrifugal impeller 1 by the rotation of the centrifugal impeller 1 can be efficiently guided to the discharge port 39 by the scroll casing 40, the blowing performance is improved.

  The present invention provides a centrifugal impeller in which the difference between the direction of the blade leading edge and the air inflow direction is small, the manufacturing method is easy, and the air blowing efficiency can be improved.

The figure which shows the centrifugal impeller of Embodiment 1 of this invention ((a) The top view of the centrifugal impeller, (b) The side view of the centrifugal impeller) The figure which shows the blade shape of Embodiment 1 of this invention. The figure which shows the blade entrance angle of Embodiment 1 of this invention The figure which shows the manufacture process of the braid | blade of Embodiment 1 of this invention ((a) Side view of the blade, (b) The top view of the blade, (c) One direction so that the blade may become a convex circular arc. Plan view in a curved state only) The figure which shows the air inflow angle of Embodiment 1 of this invention The figure which shows the airfoil blade cross section of Embodiment 1 of this invention The figure which shows the braid | blade cross section which enlarged the thickness of the front edge part of Embodiment 1 of this invention ((a) The figure which shows the increase in the reverse rotation direction side thickness of the braid | blade cross section, (b) The rotation direction of the braid | blade cross section The figure which shows the increase in the thickness of the side, (c) The figure which shows the increase in the thickness on both sides of the same blade cross section) The figure which shows the centrifugal impeller of Embodiment 2 of this invention ((a) The top view of the centrifugal impeller, (b) The side view of the centrifugal impeller) The figure which shows the manufacture process of the braid | blade of Embodiment 2 of this invention ((a) Side view of the braid | blade, (b) Plan view of the braid | blade, (c) One direction so that the braid | blade may become a convex circular arc. Plan view in a curved state only) The figure which shows the centrifugal blower of Embodiment 3 of this invention ((a) The top view of the centrifugal blower, (b) The side view of the centrifugal blower) The figure which shows the conventional centrifugal impeller ((a) The perspective view of the centrifugal impeller, (b) The enlarged view of the blade of the centrifugal impeller)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Centrifugal impeller 2 Main plate 3 Rotating shaft 4 Air passage 5 Suction port 6 Shroud 7 Blade H Air passage exit interval 8 Blade cross section 9 Blade center line 10 Rotation direction 11 Cylindrical surface 12 Rotation direction side blade crossing 13 Reverse rotation direction side Blade crossing line Dbi1 Shroud joint blade inner diameter Dbi2 Main plate joint blade inner diameter Dbo Blade outer diameter 14 Blade trailing edge 15 Blade front edge 16 Circumferential tangent line 17 Blade center line tangent line α1 Shroud side blade inlet angle α2 Main plate side blade inlet angle Δα Blade Difference in entrance angle 18 Rectangular plate 19 Front edge 20 Shroud side 21 Main plate side 22 Front edge cutting line 23 Shroud side cutting line 24 Air inflow speed γ Air inflow angle 25 Radial inflow speed component 26 Front edge 1 straight line L1 Arc length T Maximum thickness Xt Maximum thickness position L2 String length Δt Seen increasing size M thickness increment 27 motor rotation shaft 28 boss 29 line a
30 straight line b
31 Centrifugal Blower 32 Outer Frame Suction Port 33 Front Plate 34 Back Plate 35 Scroll Plate 36 Front Plate Edge 37 Rear Plate Edge 38 Scroll Plate Edge 39 Discharge Port 40 Scroll Casing

Claims (10)

Sandwiched between the main plate and the shroud, a disk-shaped main plate having a rotation shaft at the center, a donut-shaped shroud disposed so as to face the main plate with an air passage interval centered on the rotation shaft A centrifugal impeller having a plurality of blades arranged in an annular shape, and a blade center line of a cross section of an arbitrary plane perpendicular to the rotation axis is convex with respect to the rotation direction, the blade curved surface and the rotation axis The intersecting line of an arbitrary cylindrical surface as a center is parallel to the rotation axis, and the blade entrance angle formed by the tangent line between the rotation direction side circumferential tangent of the blade leading edge and the blade center line is greater on the main plate side than on the shroud side. Centrifugal impeller characterized by being small. 2. The centrifugal impeller according to claim 1, wherein the trailing edge of the blade is parallel to the rotation axis. The centrifugal impeller according to claim 1 or 2, further comprising a blade having a difference between a blade inlet angle on the shroud side and a blade inlet angle on the main plate side that is greater than 0 ° and equal to or less than 15 °. The centrifugal impeller according to any one of claims 1 to 3, wherein a blade inlet angle is equal to an air inflow angle at an arbitrary blade cross section. The centrifugal blade according to any one of claims 1 to 4, wherein the blade is expanded in a circumferential direction so that a center line of an arbitrary blade cross section is a straight line, and a leading edge is a straight line. car. The centrifugal impeller according to any one of claims 1 to 4, wherein the blade inner diameter on the main plate side suddenly expands at an arbitrary blade cross section. The centrifugal impeller according to any one of claims 1 to 6, wherein the inner diameter of the shroud is equal to or less than the inner diameter of the blade. The centrifugal impeller according to any one of claims 1 to 7, which has a blade whose arbitrary blade cross-sectional shape is an airfoil. The centrifugal impeller according to any one of claims 1 to 7, wherein the blade has an arbitrary blade cross-sectional shape and the leading edge has a large thickness. A centrifugal blower comprising: the centrifugal impeller according to any one of claims 1 to 9; and a scroll casing that guides a discharge flow of the centrifugal impeller to a discharge port in a spiral shape.

Images