JPH0921398A - Centrifugal blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a reverse flow at the tips of the vanes, and to improve the air blasting property, by forming a baffle plate whose diameter is contracted gradually toward the tips of the vanes, and making the outer diameter of the large diameter end of the baffle plate smaller than the inner diameter of the small diameter part of a shroud. SOLUTION: On the outer periphery of the tip 13a of each vane 13 at the suction side of an operating fluid such as the air, a shroud 14 of a divergent cylindrical form bending continuously from the vertical surface to the horizontal surface is fitted from the outer side and fixed concentrically. At the intermediate part of each vane 13 between the shroud 14 and a substrate 12, a hanging bell form of baffle plate 15 is provided concentrically to the vane line. The baffle plate 15 is formed in the hanging bell form at the intermediate part in the axial direction of the vanes 13, expanding in a trampet form to the lower side by a recessed arc surface 15a projecting to the inner side, and both ends in the axial direction are opened. The suction air is led in to the shroud 14 and the baffle plate 15, and the ventilating passages between the vanes 13, and discharged to the outer side from the recessed arc surface 15a of the baffle plate 15. Consequently, the reverse flow at the tips of the vanes 13 can be prevented so as to improve the air blasting property.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal blower suitable as a fan for an air conditioner.

[0002]

2. Description of the Related Art Conventionally, as an example of this type of centrifugal blower, one having a structure shown in FIG. 7 is known. The centrifugal blower 1 is rotatably accommodated in, for example, a spiral casing (not shown), is long on the outer peripheral portion of one surface of the disk-shaped substrate 2, and is long in the direction parallel to the axis of the substrate 2. A large number of arcuate blades 3 inclined forward with respect to the rotation direction are arranged annularly at a predetermined interval in the circumferential direction. A ring 4 is concentrically fixed to the substrate 2 at the tip of each blade 3 opposite to the substrate 2.

A boss portion 2a is formed in the axial center portion of the substrate 2, and a rotary shaft of a motor (not shown) is connected to the boss portion 2a to rotate in a predetermined direction, whereby an arrow in the drawing As shown in FIG. 5, a working fluid such as air is sucked from the inner peripheral side of the tip end of each blade 3, and is discharged outward from the gap between the blades 3 in the centrifugal direction.

[0004]

However, in the conventional centrifugal blower 1 as described above, the axial direction (longitudinal direction) from the air suction side tip of each blade 3, that is, the tip of each blade 3 (upper end in FIG. 7). For example, at the tip of about 25 to 40% of the total length downward, the air flow on the discharge side flows backward with respect to the flow of other parts, reducing the aerodynamic efficiency and reducing the centrifugal blower 1 However, there is a problem that the air blowing performance is deteriorated.

Therefore, in recent years, the centrifugal blower 1 shown in FIG.
A is proposed. This centrifugal blower 1A is characterized in that the blade tip portion is formed as a mixed flow fan portion. That is, in this centrifugal blower 1A, an annular shroud 6 is concentrically provided at the tip end portion of each blade 3 on the outer peripheral side of the bell mouth 5 for guiding the suction air flow into the inner peripheral portion of the blade row. Further, a plurality of auxiliary blades 3a are arranged on the shroud 6 at a required pitch in the circumferential direction to form an auxiliary mixed flow fan portion, and in particular, the air blowing performance of the blade tip portion is improved.

However, in this centrifugal blower 1A, although the blowing performance of the blade tip portion is improved, since the blade 3 and the auxiliary blade 3a are independent of each other, it is necessary to mold and assemble them separately. Therefore, there are problems that the number of manufacturing steps is large, the assembling workability is low, and the assembling accuracy is not always easy to maintain.

Therefore, an object of the present invention is to provide a centrifugal blower which can improve both blowing performance and manufacturing workability and can easily maintain the assembly accuracy.

[0008]

According to a first aspect of the present invention, there is provided a substrate which is rotated around an axis and an identical cross section which is annularly arranged on one surface of the substrate at a predetermined interval in the circumferential direction. A plurality of shaped blades and are arranged so as to circumferentially connect adjacent blades at the tip of these blade rows, and a concave arc that is convex inward from the inner end to the outer end of each blade A shroud that is curved by the surface and gradually reduces in diameter toward the tip of each blade,
The blades are arranged so as to connect adjacent blades in the circumferential direction in the blade row intermediate portion between the shroud and the substrate, and are convex inward from the inner end to the outer end of each blade. An air guide plate that is curved by the concave arc surface and that gradually reduces its diameter toward the tip of each blade, and forms the large-diameter end outer diameter of the baffle plate to be smaller than the small-diameter end inner diameter of the shroud. doing.

According to a second aspect of the present invention, there is provided a substrate which is rotated about an axis, and a plurality of blades having the same cross-sectional shape which are annularly arranged on one surface of the substrate at a predetermined interval in the circumferential direction. The blades are arranged so as to connect adjacent blades in the circumferential direction at the tip of the blade row, and are curved inward from the inner end to the outer end of each blade by a concave arc surface, The shroud is gradually reduced in diameter toward the tip of each blade, and the blades are arranged so as to circumferentially connect adjacent blades in the blade row intermediate portion between the shroud and the substrate. And a wind guide plate that is curved inwardly from the inner end toward the outer end of the concave arc surface and that gradually reduces in diameter toward the tip of each blade. Is divided into two parts in the axial direction, and the mounting positions of the one end and the other end of the blade are circumferentially separated from each other. Shifting to constitute.

Here, the substrate is formed, for example, in an annular shape or a disk shape, and the blade is made of, for example, a vertically long arcuate plate which is curved so as to project in an arc shape in the rotation direction. To about 25 to 40% of the total length.
Both the shroud and the baffle plate are cylindrical bodies each having an opening at both ends whose longitudinal cross section is substantially trapezoidal, and the side peripheral surface thereof is formed as a concave arc surface.

[0011]

In each of the first and second aspects of the invention, the working fluid such as air sucked inward from the blade tip portion is guided to the outer peripheral side between the blades along the concave arc surface of the baffle plate. Therefore, it is possible to effectively prevent the backflow from occurring in the flow at the tip of the blade row and stabilize the air flow. Therefore, the fan efficiency and the flow rate characteristic at the tip of the blade row can be improved, which in turn can improve the air blowing performance of the centrifugal fan as a whole.

Since the blades have the same sectional shape in the direction perpendicular to the axis, the blades and the substrate, or the blades and the baffle plate can be integrally formed by injection molding of synthetic resin or the like.

Therefore, the number of manufacturing steps can be reduced to improve the manufacturing workability, and the assembling accuracy can be easily maintained.

Further, according to the invention of claim 1, since the large diameter end outer diameter of the baffle plate is formed to be smaller than the small diameter end inner diameter of the shroud, the baffle plate and the shroud are arranged in the axial direction of each blade. There is no overlap.

Therefore, since each blade, shroud, and air guide plate can be easily integrally formed by injection molding of synthetic resin, the centrifugal blower can be assembled only by the step of assembling this integrally formed product on the substrate. Therefore, the manufacturing workability can be improved and the assembling accuracy can be easily maintained.

According to a second aspect of the present invention, each blade is divided into one end portion (upper portion) and the other end portion (lower portion) around the baffle plate, and the two blades are arranged so as to be offset from each other in the circumferential direction. Therefore, the phases of these two wings during rotation are different. Therefore, it is possible to reduce the narrow band sound generated by the velocity loss region of the wake behind the blade. That is, the quietness can be improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 6, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a vertical cross-sectional view of a first embodiment of the present invention. In the drawing, a centrifugal blower 11 connects a rotating shaft of a fan motor (not shown) to the shaft center of a disk-shaped or annular substrate 12. The boss portion 12a is formed so that the boss portion 12a can be rotated about its axis O.

The substrate 12 has a large number of blades 13 made of vertically elongated arc-shaped plates in the figure on the outer peripheral edge of one surface (the upper surface in FIG. 1) of the substrate 12.
Are arranged in an annular shape at a predetermined interval in the circumferential direction. The blades 13 are arranged in parallel to the axis O of the substrate 12 and have the same cross-sectional shape in the direction perpendicular to the axis. Moreover, the substrate 12 is inclined forward with respect to the predetermined rotation direction.

Then, a divergent cylindrical shroud 14 is provided on the outer circumference of the suction-side tip portion 13a of the working fluid such as air of each blade 13.
Is fitted and fixed. That is, about 25 to 4 of the total length from the air suction side tip of each blade 13 (upper end in FIG. 1).
The outer corner portion of the tip portion 13a up to 0% is cut off with an inwardly convex concave arc surface 13b which continuously curves from a vertical surface to a horizontal plane,
The concave arc surface 1 is formed on the outer peripheral surface of each of these 13 concave arc surfaces 13b.
A concave arc surface conforming to 3b spreads downwardly in FIG. 1 in a trumpet shape, and a divergent cylindrical shroud 14 that continuously curves from a vertical surface to a horizontal surface is concentrically fitted and fixed. There is.

Also, the shroud 14 of each blade 13 and the substrate 1
A bell-shaped wind guide plate 15 is concentrically arranged in the blade row at an intermediate portion between the two.

The baffle plate 15 is an axially intermediate portion of each blade 13 and has a concave arc surface 1 which is convex inward from its inner end toward its outer end.
It is formed in a bell shape that expands downward in FIG. 1 in a trumpet shape by 5a, and both ends in the axial direction (upper and lower ends in FIG. 1) are opened.

An inverted bell-shaped bell mouth 16 is concentrically arranged above the shroud 14 in FIG. The bell mouth 16 forms a suction port 16a for sucking a working fluid such as air inward of the blade row, and the diameter-reduced lower end portion of the bell mouth 16 slightly extends toward the inner peripheral side of the shroud 14 and terminates. A slight gap is provided in the radial direction between the outer peripheral surface of the terminal end portion and the inner peripheral surface of the upper end portion of the shroud 14 in the figure.

Therefore, when the substrate 12 is rotated around the axis by a fan motor (not shown), the air is guided by the inner bell mouth 16 as shown by the arrow in FIG. It is sucked into the inner circumference of the 13th row of blades. In addition, the sucked air is
Is introduced into the shroud 14 and the air guide plate 15 and the air passages between the adjacent blades 13 at the tip end of the air guide plate 1.
5 is guided by the concave arc surface 15a and discharged outward in the centrifugal direction. Therefore, the backflow at the tip portion of each blade 13 is effectively prevented, the blast is stabilized, and the blast flow rate is increased. As a result, the blowing performance of the centrifugal blower 11 as a whole can be improved.

FIG. 2 shows the blower characteristics of the centrifugal blower 11 of the present embodiment thus constructed and the conventional centrifugal blower 1 shown in FIG. 7 under the same conditions, and the solid line in FIG. The blast characteristic of the embodiment is shown, and the broken line shows the blast characteristic of the conventional example.

As shown in FIG. 2, the centrifugal blower 1 of this embodiment
It has been found that the fan No. 1 has both higher fan efficiency and flow rate characteristics than the conventional centrifugal fan 1, and has improved air blowing performance.

Since the blades 13 have the same sectional shape in the direction perpendicular to the axis, the blades 13 and the substrate 12, or the blades 13 and the baffle plate 15 or the shroud 14 are integrally molded by injection molding of synthetic resin or the like. can do.

Therefore, the number of manufacturing steps can be reduced to improve the manufacturing workability, and the assembling accuracy can be easily maintained.

FIG. 3 is a longitudinal sectional view of a main part of a centrifugal blower 11A according to a second embodiment of the present invention, and FIG. 4 is a plan view of the main part. The centrifugal blower 11A has a large-diameter opening of the baffle plate 15. The outer diameter of the end (the lower end in FIG. 3) is reduced to be equal to or smaller than the inner diameter of the small-diameter open end of the shroud 14, and the outside of the baffle plate 15 that overlaps the shroud 14 in the axial direction of each blade 13 is shown by the broken line in FIG. It is characterized in that the end portion 15b is deleted.

Therefore, the baffle plate 15 and the shroud 14
Since there is no portion in which the blades 13 overlap each other in the axial direction, the blades 13, the shroud 14, and the baffle plate 15 can be easily integrally formed by injection molding of synthetic resin.
As a result, the centrifugal blower 11A can be assembled and manufactured only by the step of assembling this integrally molded product on the substrate 13.
Therefore, the manufacturing workability can be improved and the assembling accuracy can be easily maintained.

FIG. 5 is a plan view of a main portion of a centrifugal blower 11B according to a third embodiment of the present invention, and FIG. 6 is a view showing both a vertical sectional view and a perspective view thereof. The centrifugal blower 11B has a baffle plate. 1
5, each blade 13 is divided into an upper portion 13c and a lower portion 13d, and the upper blade 13c and the lower blade 13d are arranged so as to be displaced from each other in the circumferential direction by a predetermined amount, thereby rotating the both blades 13c and 13d. It is characterized in that it is configured so that the phases of time are different.

As a result, it is possible to reduce the narrow band sound generated by the velocity loss region in the wake of each blade 13 during the rotation of the centrifugal blower 11B. That is, the quietness can be improved.

[0033]

As described above, in each of the first and second aspects of the present invention, the working fluid such as air sucked inward in the blade tip portion is moved along the concave arc surface of the baffle plate to each blade. Since it can be guided to the outer peripheral side of the blade, it is possible to effectively prevent the backflow from occurring in the flow at the tip of the blade row and to stabilize the blown air. Therefore, the fan efficiency and the flow rate characteristic at the tip of the blade row can be improved, which in turn can improve the air blowing performance of the centrifugal fan as a whole.

Since the blades have the same sectional shape in the direction perpendicular to the axis, the blades and the substrate, or the blades and the baffle plate can be integrally formed by injection molding of synthetic resin or the like.

Therefore, the number of manufacturing steps can be reduced to improve the manufacturing workability, and the assembling accuracy can be easily maintained.

Further, in the invention of claim 1, the large diameter end outer diameter of the baffle plate is formed smaller than the small diameter end inner diameter of the shroud. Therefore, the baffle plate and the shroud are arranged in the axial direction of each blade. There is no overlap.

Therefore, since each blade, shroud, and air guide plate can be easily integrally formed by injection molding of synthetic resin, the centrifugal blower can be manufactured only by the step of assembling this integrally formed product on the substrate. . For this,
The manufacturing workability can be improved, and the assembling accuracy can be easily maintained.

According to the second aspect of the present invention, each blade is divided into one end portion (upper portion) and the other end portion (lower portion) around the baffle plate, and both blades are arranged so as to be offset from each other in the circumferential direction. Therefore, the phases of these two wings during rotation are different. Therefore, it is possible to reduce the narrow band sound generated by the velocity loss region of the wake behind the blade. That is, the quietness can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a centrifugal blower according to a first embodiment of the present invention.

FIG. 2 is a graph showing the fan characteristics of the first embodiment shown in FIG. 1 in comparison with those of the conventional example.

FIG. 3 is a longitudinal sectional view of a main part of a second embodiment of the present invention.

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a plan view of an essential part of a third embodiment of the present invention.

FIG. 6 is a diagram showing both a vertical cross-sectional view and a perspective view of FIG. 5;

FIG. 7 is a perspective view of a conventional centrifugal blower.

FIG. 8 is a partial cross-sectional view of another centrifugal blower.

[Explanation of symbols]

 11, 11A, 11B Centrifugal blower 12 Substrate 12a Substrate boss portion 13 Blade 13a Blade tip 13c Upper blade 13d Lower blade 14 Shroud 15 Wind guide 16 Bell mouth 16a Suction port O Shaft center

Claims (2)

[Claims] 1. A substrate rotated about an axis, a plurality of blades having the same cross-sectional shape and annularly arranged on one surface of the substrate at predetermined intervals in the circumferential direction, and the blade row tips. Are arranged so as to connect adjacent blades in the circumferential direction to each other, and are curved inward from the inner end of each blade toward the outer end by a concave arc surface, and to the tip of each blade. The shroud is gradually reduced in diameter, and the blades are arranged so as to circumferentially connect adjacent blades in the blade row intermediate portion between the shroud and the substrate. An air guide plate that is curved inward toward the end by a concave arc surface and that gradually reduces its diameter toward the tip of each blade, and the large-diameter end outer diameter of the air guide plate is set to the shroud. The centrifugal blower is characterized in that it has a smaller diameter than the inner diameter of the small diameter end. 2. A substrate rotated about an axis, a plurality of blades having the same cross-section and annularly arranged on one surface of the substrate at a predetermined interval in the circumferential direction, and the blade row tips. Are arranged so as to connect adjacent blades in the circumferential direction to each other, and are curved inward from the inner end of each blade toward the outer end by a concave arc surface, and to the tip of each blade. The shroud is gradually reduced in diameter, and the blades are arranged so as to circumferentially connect adjacent blades in the blade row intermediate portion between the shroud and the substrate. An air guide plate that is curved inwardly toward the end by a concave arc surface and that gradually reduces its diameter toward the tip of each blade, and each of the blades is centered around the air guide plate. The blade is divided into two parts each in the same direction, and the mounting positions of its one end and the other end of the blade are offset from each other in the circumferential direction. Centrifugal blower characterized by.