JP2000009083A - Impeller - Google Patents

Abstract

(57) [Problem] It is an object of the present invention to reduce ventilation efficiency and increase noise due to a separation flow generated between blades of a multi-blade blower. SOLUTION: The impeller of the present invention has a configuration in which a blade 4 is annularly disposed on a main plate and the other end is supported by a sub plate.
Is a blade shape in a cross section cut by a plane perpendicular to the rotation axis,
A substantially semicircular projection 19 is provided on the rear side 15 of the front edge 13. For this reason, the leading edge radius becomes large, and even if the inflow angle of the flow and the inlet angle of the blade slightly shift, a wraparound flow at the leading edge 13 is likely to occur. Therefore, even if the inflow angle slightly changes depending on the flow condition, abrupt separation at the leading edge 13 can be suppressed, so that performance can be maintained over a wide operating point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-blade blower used for home air conditioners and the like, and more particularly to a resin-molded impeller.

[0002]

2. Description of the Related Art A conventional multi-blade blower of this type has a structure in which an impeller is housed in a spiral casing 1 as shown in FIG. As shown in FIG. 7, the impeller 2 has a structure in which the blades 4 are annularly arranged on the main plate 3, and the other end is held by the sub plate 5. The shape of the sub-plate 5 is often a ring shape for integrally forming the impeller. A boss 6 is provided at the center of the main plate 3, and a drive shaft 8 of a motor 7 is provided.
Is linked to A suction port 9 is provided on a casing surface of the impeller 2 opposite to the sub-plate 5, and a bell mouth 10 is formed so that air can flow in smoothly. A discharge port 11 is formed at an end of the casing 1.

In such a configuration, by rotating the impeller in the direction of arrow 12 using a motor, the air sucked from the suction port 9 is blown out from the impeller 2 in the centrifugal direction, and the flow is transmitted through the casing 1. To perform the operation of blowing out from the discharge port 11 in one direction.

As the blades of this impeller, airfoils having a certain thickness distribution are often used as shown in FIG.
13 is the leading edge at the flow entry side and 14 is the trailing edge at the flow exit end. Leading edge 13 and trailing edge 14
Is a length of the blade and is called a chord. There are various famous airfoils such as the NACA airfoil, but the most commonly used airfoil for multi-blade blowers is shown in Fig. 8.
As shown in FIG. 2, the arc of the leading edge 13 and the arc of the trailing edge 14 are connected by arcs on the back side 15 and the ventral side 16, respectively. The curve 17 connecting the center of the wing thickness is also an arc, which is called a warp line. Also, the leading edge 13,
The radius of the arc forming the trailing edge 14 is called the leading edge radius and the trailing edge radius. The simple airfoil is thickest at the center of the wing and thinner at both ends. The distance between the chord and the warp line is referred to as a warp height H. In the case of a simple airfoil, the warp height is greatest at the center of the chord.

The angle β1 between the warp line 17 and the circumferential direction at the front edge 13 is the entrance angle, and the warp line 1 is
The angle β2 formed by 7 and the circumferential direction is called an exit angle. In a general multi-blade fan of this type, the inlet angle β1 is set to 80 to 90 degrees, and the outlet angle β2 is set to 160 to 170 degrees.

[0006]

However, in the conventional multi-blade blower described above, there is a problem that the flow does not sufficiently follow the blade and large separation occurs, thereby lowering the blowing efficiency and increasing noise. That is, as shown in FIG. 8, the back surface of the blade 4 is largely curved, but the flow is not completely along the blade 4 and separates near the center of the chord where the warp height H is the largest. A peeling area 18 is formed. The flow between the blades of the impeller is expected to ideally all flow along the blade surface, but in practice,
Such peeling has occurred. Where and what kind of separation area occurs depends on the shape of the blades and the operating point of the blower and cannot be unconditionally determined. However, a large difference between the inflow flow at the leading edge 13 and the entrance angle β1 causes large separation. Become a factor. That is, since the inlet angle β1 is set at 80 to 90 degrees, if the relative velocity of the inflow is substantially in the radial direction, the inflow will flow smoothly along the blade. However, in the case of this type of multi-blade blower, the angle of the inflow is often smaller than the inlet angle β1, so that
The flow is pressed against the abdominal surface 16 of the blade 4, and separation occurs on the back surface of the blade as shown in FIG. 8. This is more remarkable as the chord L is shorter and the blades 4 are more curved.

The separation region 18 is a region in which turbulence is strong and vortices are concentrated. The separation region 18 causes noise, narrows an effective flow path between the blades, and increases the passage resistance. Has become.

[0008]

In order to solve the above-mentioned problems, a multi-blade blower according to the present invention comprises a sub-plate in which a plurality of blades are annularly arranged on a main plate and the other end of the blades is connected. The blade has a configuration in which a blade shape in a cross section taken along a plane perpendicular to the rotation axis is provided with a substantially semicircular convex portion on the back side of the front edge.

According to the above invention, since the substantially semicircular convex portion is provided on the back side of the front edge of the blade, the thickness of the front edge is increased and the radius of the front edge is increased. If the leading edge radius is increased, peeling is less likely to occur even if the entrance angle β1 and the inflow angle slightly deviate. For example, in the case of a blade having a very small leading edge radius, that is, a blade having a sharp leading edge, a slight deviation between the inflow angle and the entrance angle may cause separation. When the flow near the leading edge is considered in detail, in order to flow without separation, it is necessary to flow at a very high speed and turn around rapidly. However, such a flow does not actually occur, and the wraparound is insufficient to separate from the blade surface and separate.

However, when the leading edge has a large radius, it flows along the leading edge, so that the blade can go around the back side. That is, the flow velocity and the direction change of the wraparound flow become gentle. Therefore, even if the inflow angle slightly changes depending on the flow condition, the rapid separation at the leading edge can be suppressed, and the performance can be maintained over a wide operating point.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An impeller according to a first aspect of the present invention includes a sub-plate in which a plurality of blades are annularly arranged on a main plate and the other end of the blade is connected to the sub-plate. The blade shape in a cross section cut along a plane perpendicular to the axis has a substantially semicircular convex portion on the back side of the front edge.

According to the above configuration, since the radius of the leading edge is increased by providing the substantially semicircular convex portion on the back side of the leading edge, even if the inflow angle of the flow and the inlet angle of the blade slightly deviate, the leading edge becomes larger. A wraparound flow at the edge is likely to occur. For this reason, even if the inflow angle slightly changes depending on the flow conditions, it is possible to suppress abrupt separation at the leading edge, so that performance can be maintained over a wide operating point.

In the impeller according to the second aspect of the present invention, the radius of curvature of the substantially semicircular convex portion is set to be 2 times the radius of curvature of the front edge on the ventral surface side.
2. The method according to claim 1, wherein the number is twice or more.

According to a third aspect of the present invention, there is provided an impeller including a plurality of blades arranged in a ring on a main plate, and a sub-plate connecting the other ends of the blades, wherein the blades are perpendicular to a rotation axis. The blade shape in the cross section cut along the plane has at least one recess between the leading edge and the maximum warped position and on the back side.

According to the above construction, at least one concave portion is provided between the leading edge on the back side of the blade and the maximum warpage position, and the negative pressure due to the circulating flow and the mixing effect of the flow at that portion cause the back surface of the blade. The effect of suppressing flow separation on the side is obtained. Therefore, even if the inflow angle slightly changes depending on the flow condition, the separation on the back side can be suppressed, and the performance can be maintained over a wide operating point.

In the impeller according to a fourth aspect of the present invention, the inner diameter of the blade on the main plate side is smaller than that of the sub-plate side, and the position of the concave portion is closer to the maximum warp position on the main plate side. It is.

According to the above configuration, a so-called tapered blade is formed in which the chord of the blade is longer toward the main plate. The tapered blade has a short chord on the sub-plate side serving as a suction port and a wide opening, and the main plate side serving as a main flow has a long chord blade to efficiently blow air. By changing the position of the concave portion on the blade rear side between the main plate side and the sub-plate side, it is possible to provide the concave portion even in the case of a resin integrally molded blade. Therefore, even if the inflow angle slightly changes depending on the flow condition, the separation on the back side can be suppressed, and the performance can be maintained over a wide operating point.

The impeller according to claim 5 of the present invention is the impeller according to claim 3, wherein the blade has an inner diameter smaller on the main plate side than on the sub plate side, and the number of the concave portions is different on the main plate side and the sub plate side. is there.

According to the above configuration, a large number of concave portions are provided in the blade portion having a long chord on the main plate side, and the number can be reduced on the sub-plate side having a short chord. By changing the number of recesses according to the length of the chord, the effect of preventing peeling can be effectively utilized, and the performance can be maintained over a wide operating point.

According to a sixth aspect of the present invention, there is provided an impeller comprising: a plurality of blades arranged in a ring on a main plate; and a sub-plate connecting the other ends of the blades, wherein the blades are perpendicular to a rotation axis. The blade shape in the cross section cut along the plane has a flat portion substantially parallel to the chord on a part of the back side.

According to the above configuration, the swelling on the back side of the blade is reduced and the flow path between the blades is widened, so that not only the air volume performance can be improved, but also the separation on the trailing edge side of the back side of the blade hardly occurs. . In addition, since the area becomes smaller even when it occurs, the performance degradation can be reduced.

The impeller according to a seventh aspect of the present invention is the impeller according to the sixth aspect, wherein the blade has a substantially semicircular convex portion on the back side of the front edge.

The impeller according to claim 8 of the present invention is the impeller according to claim 6, wherein the blade has at least one concave portion on the back side between the front edge and the maximum warpage position.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. Components common to the conventional example are denoted by the same reference numerals.

(Embodiment 1) FIG. 1 is an enlarged view of a blade of an impeller according to Embodiment 1 of the present invention. As in the conventional example, the blades 4 of the impeller housed in the spiral casing are arranged in an annular shape on the main plate, and have a structure in which the other end is supported by a sub plate. The shape of the blade 4 is such that a substantially semicircular convex portion 19 is provided on the rear side 15 of the front edge 13. Feather 4
Is formed so as to extend between the main plate and the sub-plate, the three-dimensional shape of the substantially semicircular projection 19 is a substantially semicircular column provided on the back side of the front edge 13 of the blade 4.

The flow of the airflow around the blade 4 will be described. As shown in FIG. 1, the flow flowing from the leading edge 13 is
The water flows separately from the rear surface 15 and the abdominal surface 16 of the blade 4, and flows out from the trailing edge 14. At this time, the angle flowing into the blade 4 is determined by the absolute speed of the flow and the rotation speed of the impeller. In general, it is often the angle from the abdominal surface of the blade 4 to the rear surface.

Next, the operation of the substantially semicircular projection 19 will be described. By providing the substantially semicircular convex portion 19 on the back side 15 of the front edge 13, the front edge radius increases,
The effect of smooth flow of the flow from the abdominal surface to the back surface is obtained. In addition, a small recess 20 formed by the rear edge of the blade and the rear edge of the substantially semicircular projection 19 has a rear side 1.
A secondary flow is formed which stabilizes the flow of 5. Depression 20
The secondary flow formed is a minute circulating flow, and the flow on the back side of the blade is drawn by the vortex, so that separation is suppressed.

As described above, even if the flow inflow angle and the inlet angle of the blade 4 are different from each other, the flow smoothly proceeds to the rear side along the substantially semicircular convex portion 19 and the concave 2 on the rear side.
The formation of the secondary flow at 0 suppresses separation at the back surface 15. Therefore, the peeling area 21 formed on the back side of the trailing edge 14 is extremely small, and high performance with low noise and large air volume can be maintained. Further, since the substantially semicircular convex portion 19 is provided only on the back side of the front edge 13 and is not provided on the unnecessary abdominal surface side, the effective flow path at the front edge can be widened, and the inflow resistance can be reduced. Can be suppressed. Note that a clear effect can be obtained by setting the radius of curvature of the substantially semicircular convex portion to be at least twice the radius of the leading edge on the abdominal surface side without the convex portion.

(Embodiment 2) FIG. 2 is an enlarged view of a blade of an impeller according to Embodiment 2 of the present invention. As in the first embodiment, the impeller has a structure in which the blades 4 are arranged in an annular shape on the main plate, and the other end is supported by the sub plate. The blade 4 has at least one recess 22 formed between the front edge 13 and the maximum warped position and on the back side 15. When viewed in three dimensions, the recess 22 is a groove provided on the back side 15 of the blade 4, that is, a groove extending from the main plate side to the sub plate side.
The flow state around the blade 4 is the same as that described in the first embodiment.

Next, the operation of the recess 22 will be described.
A secondary flow is formed in the recess 22 by the airflow flowing on the back side 15. This secondary flow is a stable circulating flow swirling in the concave portion 22 and has an effect of suppressing separation of the flow on the rear side 15. Because, in order for the flow to separate in the vicinity of the concave portion, it is necessary to break the stable circulating flow of the concave portion 22, which requires a correspondingly large amount of energy.

By the action of the concave portion 22 provided on the back side of the blade as described above, the separation on the back side 15 between the blade front edge 13 and the maximum warpage position is suppressed. Therefore, the peeling area 21 formed on the back side of the trailing edge 14 is extremely small, and high performance with low noise and large air volume can be maintained.

(Embodiment 3) FIG. 3 is an enlarged view of a blade of an impeller according to Embodiment 3 of the present invention. As in the first embodiment, the impeller has a structure in which the blades 4 are arranged in an annular shape on the main plate, and the other end is supported by the sub plate. In this impeller, the inner diameter of the blade 4 on the main plate side is smaller than that of the sub-plate side, and has a concave portion 23 on the back side as in the second embodiment. If the inner diameter of the blade 4 is Rh on the main plate side and Rs on the sub plate side, Rs> Rh. Therefore, if the front edge on the main plate side is 24,
The leading edge on the sub-plate side is 25, and the middle leading edge is 26. Here, the warp line 17 extends from the main plate side to the sub plate side.
Is constant, so that the entrance angle β1 on the main plate side and the entrance angle β3 on the auxiliary plate side have different values. As described above, the tapered blades having different blade inner diameters on the main plate side and the sub-plate side reduce inflow resistance by expanding the sub-plate side serving as an inlet, and utilize a long chord on the main plate side serving as a main flow of the flow. To provide effective blowing.

The concave portion 23 provided on the rear side is closer to the maximum warp position on the main plate side, and closer to the front edge on the sub-plate side. The function of the concave portion 23 is the same as that described in the second embodiment, and the secondary flow formed in the concave portion 23 has an effect of suppressing the separation on the rear surface side. Here, the recess 23
By changing the position in the chord direction where the is provided between the main plate side and the sub plate side, the concave portion 23 can be formed so as to overlap in the span direction as shown in FIG.

As described above, the concave portions 23 are used so as to overlap in the span direction by using the constant warp line 17 from the main plate side to the sub plate side.
By providing the blades, the blades have no twist in the span direction, so that the integral molding of the resin is facilitated. By being able to be integrally molded, not only can production be simplified,
There is an effect that a strong product can be obtained in terms of strength.

(Embodiment 4) FIG. 4 is an enlarged view of a blade of an impeller according to Embodiment 4 of the present invention. As in the first embodiment, the impeller has a structure in which the blades 4 are arranged in an annular shape on the main plate, and the other end is supported by the sub plate. In this impeller, the inner diameter of the blade 4 on the main plate side is smaller than that of the sub-plate side, and has a concave portion 23 on the back side as in the third embodiment. When the inner diameter of the blade 4 is Rh on the main plate side and Rs on the sub plate side, the point of Rs> Rh and the effect of the tapered blade are the same as those of the fourth embodiment. The difference from the fourth embodiment is the number of concave portions provided on the back side.

Concave portions 23 and 27 are provided on the back side. The concave portion 23 is formed over the entire span from the main plate side to the sub plate side, but the concave portion 27 is cut off from the main plate side to the sub plate side. When viewed three-dimensionally, these recesses are several grooves provided on the back side of the blade 4.

The functions of the recesses 23 and 27 are the same as those described in the second embodiment, and the secondary flow formed in the recesses 23 and 27 has the effect of suppressing the separation on the back side. Here, by providing not only the concave portion 23 over the entire span but also the concave portion 27 halfway on the main plate side,
Since the recess can be provided closer to the front edge,
It becomes possible to suppress peeling near the leading edge.

As described above, the concave portions 2 are used so as to overlap in the span direction by using the constant warp line 17 from the main plate side to the sub plate side.
By providing the blades 3 and 27, the blades have no twist in the span direction, so that the resin can be integrally molded, and the concave portion 27 is added near the leading edge to effectively suppress the peeling near the leading edge. Can be.

(Embodiment 5) FIG. 5 is an enlarged view of a blade of an impeller according to Embodiment 5 of the present invention. As in the first embodiment, the structure of the impeller is annularly arranged on the main plate, and the other end is supported by the sub plate. The blade 4 has a shape having a flat portion 28 substantially parallel to the chord on a part of the back side.

According to the above configuration, the swelling on the back side of the blade is reduced and the flow path between the blades is widened, so that not only the air volume performance can be improved, but also the separation on the trailing edge side of the back side of the blade hardly occurs. . Further, even when it occurs, the peeled area 21 becomes smaller, so that an increase in noise and the like can be suppressed.

By providing a substantially semicircular convex portion on the back side of the front edge 13 or providing a concave portion on the contrary,
Since the same peeling suppressing effect as described in Examples 1 to 4 can be obtained, the performance can be further improved.

[0042]

As described above, according to the impeller of the present invention,
Since the radius of the front edge is increased by providing the substantially semicircular convex portion on the back side of the front edge, a wraparound flow at the front edge is likely to occur, so that separation at the front edge can be suppressed,
The effect is that the performance is maintained over a wide operating point.

Further, by providing at least one concave portion between the leading edge on the back side of the blade and the maximum warping position, the negative pressure and the mixing effect of the flow due to the circulating flow at that portion provide
The effect of suppressing flow separation on the blade back side and maintaining high performance over a wide operating point is obtained.

Further, by adopting a so-called tapered blade in which the chord of the blade is longer toward the main plate side, and by changing the position of the concave portion on the back surface side of the blade between the main plate side and the sub-plate side, the integrally molded blade is made of resin. In this case, it is also possible to provide a concave portion, and it is possible to suppress peeling on the back side while utilizing the high performance of the tapered blade.

In addition, tapered blades are employed, and
By changing the number of recesses according to the length of the chord, such as reducing the number of recesses on the subplate side with a short chord The prevention effect can be effectively utilized.

Further, by providing a flat portion substantially parallel to the chord on a part of the back side of the blade, the flow path between the blades is expanded, so that not only the air volume performance can be improved, but also the blade rear side. On the trailing edge side, and the effect of reducing performance degradation is obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a blade of an impeller according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of an impeller blade according to a second embodiment of the present invention.

FIG. 3 is an enlarged view of an impeller blade according to a third embodiment of the present invention.

FIG. 4 is an enlarged view of an impeller blade according to a fourth embodiment of the present invention.

FIG. 5 is an enlarged view of an impeller blade according to a fifth embodiment of the present invention.

FIG. 6 is a plan view of a conventional multi-blade blower.

FIG. 7 is a longitudinal sectional view of a conventional multi-blade fan.

FIG. 8 is an enlarged view of a blade of an impeller in a conventional multi-blade blower.

[Explanation of symbols]

 Reference Signs List 1 casing 2 impeller 3 main plate 4 blade 5 sub plate 13 front edge 14 rear edge 17 warp line 19 convex portion 22 concave portion 24 main plate side front edge 25 sub plate side front edge 26 intermediate portion front edge 28 flat portion

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H031 AA00 AA03 BA02 CA02 3H033 AA02 AA18 BB02 BB06 CC01 DD04 DD06 DD09 DD12 DD25 DD26 DD27 DD30 EE06 EE08

Claims (8)

[Claims] 1. A plurality of blades are annularly arranged on a main plate, and a sub plate connecting the other ends of the blades is provided. The blades have a blade shape in a cross section cut along a plane perpendicular to a rotation axis. An impeller of a multi-blade blower having a substantially semicircular convex portion on the back side of a front edge. 2. The impeller of a multi-blade blower according to claim 1, wherein the radius of curvature of the substantially semicircular convex portion is at least twice as large as the radius of curvature of the front edge on the ventral side. 3. A plurality of blades are arranged in an annular shape on a main plate, and a sub plate connecting the other ends of the blades is provided, wherein the blades have a blade shape in a cross section cut along a plane perpendicular to a rotation axis. An impeller for a multi-blade blower having at least one concave portion between a leading edge and a maximum warped position and on a back side. 4. The impeller of a multi-blade blower according to claim 3, wherein the inner diameter of the blade on the main plate side is smaller than that of the sub-plate side, and the position of the concave portion is closer to the maximum warp position toward the main plate. 5. The impeller for a multi-blade blower according to claim 3, wherein the blade has an inner diameter smaller on the main plate side than on the sub plate side, and the number of the concave portions is different between the main plate side and the sub plate side. 6. A blade having a plurality of blades arranged in an annular shape on a main plate and a sub-plate connecting the other ends of the blades, wherein the blades have a blade shape in a cross section cut along a plane perpendicular to a rotation axis. An impeller of a multi-blade blower having a flat portion substantially parallel to the chord on a part on the rear side. 7. The impeller for a multi-blade blower according to claim 6, wherein the blade has a substantially semicircular convex portion on the back side of the front edge. 8. The impeller of a multi-blade blower according to claim 6, wherein the blade shape has at least one concave portion between the front edge and the maximum warpage position and on the back side.