JP2004360579A - Centrifugal blower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal blower capable of reducing kinds as compared with a conventional centrifugal blower without deteriorating performance. <P>SOLUTION: The centrifugal blower BB having an impeller 2 built in a volute casing 1 is provided with a discharging passage 1b provided in the casing 1 in such a manner that an axial direction center line 3 of an outlet 1c passes through an axial line of the impeller 2, and a speed reducing part 4 formed to bend outward to gradually expand a flow passage thereof along a discharging direction of fluid and efficiently reducing speed of fluid flowing inside of the same adjacently to the outlet 1c of the discharging passage 1b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a centrifugal blower provided with a spiral casing used for air conditioning equipment or ventilation equipment.
[0002]
Problems to be solved by the prior art and the invention
FIG. 5 is a diagram showing a configuration of a conventional centrifugal blower having a spiral casing. The centrifugal blower B includes a casing 10 and an impeller 11 housed in a spiral chamber of the casing 10. A predetermined distance is set between the axial center line 12 of the discharge port 10a of the casing 10 and a center line CL1 passing through the axis of the impeller 11 and in the same direction as the axial direction of the discharge port 10a (hereinafter, referred to as a first center line). They are separated and parallel.
[0003]
At the discharge port 10a of the casing 10 of the centrifugal blower B, the flow of the fluid flowing on the outer peripheral side is faster than the flow of the fluid flowing on the inner peripheral side. Therefore, when the bending direction of the pipe connected to the discharge port 10a is the same direction as the rotation direction of the impeller 11, the fluid flows along the bending of the pipe, so that a large pressure loss does not occur. If the direction is opposite to the direction of rotation of the impeller 11, the fluid in the fast flowing portion affects and causes a large pressure loss in the bent portion of the pipe. Thus, there is a problem that a predetermined air volume cannot be obtained.
[0004]
On the other hand, in the related art, as shown in FIGS. 6A and 6B, even when the fluid is discharged in the same direction (upward in the drawing), the bending of the pipe connected to the discharge port 10a of the casing 10 is made. Two types of impellers 11 having different rotation directions (clockwise or counterclockwise) and casings 10 corresponding thereto are prepared for each direction.
[0005]
The casing 10 is installed on a base 14 of the centrifugal blower B together with a motor 15 for driving the impeller 11. When the rotation direction of the impeller 11 is the same and only the fluid discharge direction 13 is changed, as shown in FIGS. 6A, 6C and 6E, the same casing 10 is connected to the axis of the discharge port 10a. It is installed on the base 14 so that the direction center line 12 substantially matches the discharge direction 13 of each fluid (upward, leftward, and rightward in the figure). However, since the shapes of the portions of the casing 10 to be attached to the base 14 are different from each other, it is necessary to prepare three types of bases 14 corresponding to the discharge direction 13 of the fluid.
[0006]
Similarly, when the rotation direction of the impeller 11 is different from the above, as shown in FIGS. 6B, 6D, and 6F, the same casing 10 has the axial center line 12 of the discharge port 10a, respectively. Is installed on the base 14 so as to substantially coincide with the fluid discharge direction 13 (upward, leftward, and rightward in the figure). Also in this case, it is necessary to prepare three types of bases 14 as in the above case.
[0007]
As described above, conventionally, it is necessary to prepare at least six types of centrifugal blowers B having the same performance. Therefore, there is a problem that productivity of the centrifugal blower B deteriorates and inventory management becomes complicated.
[0008]
To cope with this, for example, as shown in FIG. 7A, the casing 10 of the conventional centrifugal blower B shown by a two-dot chain line is replaced with the axial center line 12 of the discharge port 10a. 11 is arranged on the base 14 so as to approach the first center line CL1. Further, an elbow joint 16 is attached to the discharge port 10a of the casing 10 such that the axial center line 12 of the discharge port 10a of the casing 10 coincides with the first center line CL1 of the impeller 11. Thereby, the axial center line 12a of the discharge port 16a newly formed at the end of the elbow joint 16 coincides with the first center line CL1 of the impeller 11.
[0009]
As a result, the above-mentioned fast flowing fluid approaches the vicinity of the center of the new discharge port 16a, and the pipe connected to this discharge port 16a is bent in the same direction as the rotation direction of the impeller 11. In addition, even if it is bent in the opposite direction, it is difficult for the fluid to separate at the bent portion. As a result, it is possible to prevent a large pressure loss from occurring.
[0010]
However, in this case, since the elbow joint 16 is newly attached to the discharge port 10a of the casing 10, there is a problem that the casing 10 becomes larger and the pressure loss becomes larger as compared with the related art.
[0011]
On the other hand, in the centrifugal blower B2 disclosed in Patent Document 1, the casing 10 has an axial centerline 12 of the discharge port 10a of the first centerline of the impeller 11, as shown in FIG. A portion 17 near the discharge port 10a of the casing 10 is formed in such a shape as to be cut away so as to approach the CL1 and face in the same direction. Thus, as described above, the axial center line 12a of the newly formed discharge port 10b approaches the first center line CL1 of the impeller 11 without providing the elbow joint 16 at the discharge port 10a of the casing 10. Turn in the same direction.
[0012]
Thus, as described above, the size of the centrifugal blower B2 does not increase. However, since the diffuser portion 18 of the centrifugal blower B2 is short, the flow velocity in this portion 18 cannot be sufficiently reduced, and there is a problem that the pressure loss in this portion 18 increases and the performance of the centrifugal blower B2 decreases.
[0013]
Specifically, as shown in FIG. 8, a curve L2 of the air flow-static pressure of the centrifugal blower shown in FIG. 7B is the same as the air flow-static pressure curve L1 of the conventional centrifugal blower. In the direction in which the static pressure decreases. As a result, there is a problem that a predetermined air volume cannot be obtained at a predetermined static pressure.
[0014]
On the other hand, by increasing the length of the diffuser section 18, it is possible to suppress an increase in pressure loss.
[0015]
Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a centrifugal blower that can reduce the number of types compared to a conventional centrifugal blower without lowering performance. .
[0016]
[Patent Document 1]
JP-A-11-294393 (FIG. 1)
[0017]
[Means for Solving the Problems]
The present invention is a centrifugal blower incorporating an impeller in a spiral casing, wherein the casing has a discharge passage provided such that an axial centerline of a discharge port of the impeller passes through the axis of the impeller. In the vicinity of the discharge port of the discharge passage, the flow path is formed by curving outward so that the fluid is gradually expanded along the discharge direction, and a deceleration part for efficiently decelerating the fluid flowing inside the discharge passage. Is provided.
[0018]
According to this configuration, at the discharge port of the discharge passage of the centrifugal blower, the fluid having a high flow rate can approach the vicinity of the central portion, and the fluid flowing therethrough can be decelerated efficiently. Therefore, even if the pipe connected to the discharge passage is bent in the same direction as the rotation direction of the impeller or in the opposite direction, separation of the fluid or the like is less likely to occur at the bent portion, and no large pressure loss occurs. . Thereby, the rotation direction of the impeller of the centrifugal blower can be changed from the conventional two types to one type without lowering the performance of the centrifugal blower.
[0019]
Further, the deceleration portions may be formed on both sides in the same direction as the axial direction of the impeller near the discharge port of the discharge passage.
[0020]
Generally, the inner surfaces on both sides in the radial direction of the impeller near the discharge port of the discharge passage of the centrifugal blower are formed along the spiral shape of the casing, so that a large pressure loss does not occur in this portion. On the other hand, near the discharge port of the discharge passage of the centrifugal blower, the inner surface on both sides in the axial direction of the impeller, the width of the discharge port of the discharge passage of the centrifugal blower in the same direction as the axial direction of the impeller, Since the casing is larger than the width dimension in the same direction as the axial direction of the impeller, the casing is formed such that the distance between the inner surfaces gradually increases toward the discharge port. Therefore, the fluid flowing in the discharge passage may be separated from the inner surface of the discharge passage, and a large pressure loss may occur. Therefore, in the present invention, in order to prevent this, a speed reduction unit is provided in this portion. As a result, an increase in pressure loss can be prevented, so that a decrease in performance of the centrifugal blower can be prevented.
[0021]
Further, it is desirable that the deceleration portion is formed such that the radius of curvature of the curved portion is 5 to 20% of the inner diameter of the discharge port of the discharge passage.
[0022]
According to this configuration, the fluid flowing in the discharge passage of the centrifugal blower is efficiently decelerated in the reduction section. As a result, an increase in pressure loss can be prevented, so that a decrease in performance of the centrifugal blower can be prevented. If the radius of curvature of the curved portion of the speed reduction portion is less than 5% of the inner diameter of the discharge port of the discharge passage, the speed reduction portion is too short to efficiently decelerate the fluid. If the radius of curvature of the curved portion of the deceleration portion exceeds 20% of the inner diameter of the discharge port of the discharge passage, the casing becomes large.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a diagram showing a basic configuration example of a centrifugal blower according to an embodiment of the present invention, where (a) is a front view, (b) is a plan view, and (c) is an AA line part of (b). It is sectional drawing. FIG. 2 is a partial cross-sectional view taken along line X1-X1 to X4-X4 in FIG. FIG. 3 is a graph showing the relationship between the air volume (horizontal axis) and the static pressure (vertical axis) of the centrifugal blower. FIG. 4 is a diagram showing types of completed centrifugal blowers according to one embodiment of the present invention.
[0025]
As shown in FIG. 1A, the centrifugal blower BB includes a spiral casing 1 and an impeller 2 installed in a spiral chamber 1a of the casing 1. The casing 1 is provided with a discharge passage 1b formed so that the flow path expands from the outlet of the spiral chamber 1a. As shown in FIG. 1B, the cross section of the flow path of the spiral chamber 1a is substantially rectangular, and the cross section of the flow path gradually changes from the spiral chamber 1a to a circular shape through the circulation passage 1b, and the discharge passage 1b discharges. The outlet 1c has a circular shape.
[0026]
The axial center line 3 of the discharge port 1c substantially coincides with a center line (hereinafter, referred to as a first center line) CL1 passing through the axis of the impeller 2 and in the same direction as the axial direction of the discharge port 1c. ing. That is, the axial center line 3 passes through the axis of the impeller 2.
[0027]
Thereby, the fluid having a high flow rate can be brought close to the vicinity of the center of the discharge port 1c of the centrifugal blower BB. As a result, even if the pipe (not shown) connected to the discharge port 1c is bent in the same direction as the rotation direction of the impeller 2 or in the opposite direction, it is difficult for the fluid to be separated at the bent portion. Therefore, it is possible to prevent a large pressure loss from occurring. As described above, the rotation direction of the impeller 2 can be unified from the conventional two types to one type.
[0028]
More specifically, as shown in FIG. 1 (c), the discharge passage 1b has a speed reducing portion 4 for efficiently decelerating the fluid flowing inside, and a width direction of the casing 1 in the axial direction of the discharge passage 1b. (This is the same direction as the axial direction of the impeller 2. See the reference symbol W in FIG. 1B.) The inclined portion 5 formed by enlarging at the spread angle δ1 and the inclined portion 5 and the reduction portion 4 And a connecting portion 6 formed to be curved radially inward with a radius of curvature 2R for communication. The spread angle δ1 of the inclined portion 5 is set in advance so that the fluid does not peel off in the inclined portion 5.
[0029]
As shown in FIG. 1B, the deceleration unit 4 is provided on both sides in the width direction of the casing 1 (the hatched portion in FIG. 1B) near the discharge port 1c of the discharge passage 1b of the centrifugal blower BB. Is formed. As shown in FIG. 1C, the deceleration unit 4 has a predetermined radius of curvature R symmetrically with respect to the axial center line 3 of the discharge port 1c in a cross-sectional view taken along the line AA in FIG. And is formed to be curved radially outward.
[0030]
Further, as shown in FIGS. 2A to 2E, the radius of curvature of the curved deceleration unit 4 is X1-X1, X2-X2, AA, X3-X3, and X4- of FIG. They are R1, R2, R, R3, and R4, respectively, in a cross-sectional view taken along line X4. These have a relationship of R1>R2> R and R4>R3> R. That is, as the position in the sectional view moves away from the center of the discharge port 1c to the left or right (in the direction perpendicular to the width direction of the casing 1), the radius of curvature of the reduction unit 4 corresponding to the position gradually increases. The left and right ends of the speed reducer 4 are respectively continuous with portions 7 excluding the speed reducer 4 near the discharge port 1c of the discharge passage 1b.
[0031]
Here, it is desirable that the radius of curvature R of the deceleration section 4 is set to 0.05D to 0.2D (D is the inner diameter of the discharge port 1c of the discharge passage 1b). This is because, when the radius of curvature R of the speed reduction unit 4 is less than 5% of the inner diameter D of the discharge port 1c of the discharge passage 1b, the speed reduction unit 4 is too short to efficiently decelerate the fluid. Further, when the radius of curvature R of the speed reduction portion 4 exceeds 20% of the inner diameter D of the discharge port 1c, the casing 1 becomes large. Further, it is desirable to set the height H2 in the axial direction of the speed reducer 4 to 0.05D to 0.2D corresponding to the radius of curvature R of the speed reducer 4.
[0032]
Note that the curve of the deceleration unit 4 is actually set in advance by experiments or the like according to the air volume of the centrifugal blower, the type of fluid to be blown, and the like.
[0033]
In the deceleration section 4, the fluid flowing therethrough is efficiently decelerated, so that the axial distance of the discharge passage 1b required to decelerate the fluid can be set smaller than in the past. Conversely, when the speed reduction unit 4 is not provided in the vicinity of the discharge port 1c, the distance needs to be increased.
[0034]
More specifically, a height H from a center line (hereinafter, referred to as a second center line) CL2 passing through the axis of the impeller 2 and substantially parallel to the discharge port 1c to the discharge port 1c is, for example, the inner diameter of the discharge port 1c. D can be set to 1.5 times or less.
[0035]
As described above, the casing 1 of the centrifugal blower BB according to the present embodiment can be made more compact than the conventional one.
[0036]
Further, the inner diameter D of the discharge port 1c may be the same as the inner diameter D1 of the suction port 8 of the casing 1. Thereby, the types of the pipes connected to these can be unified.
[0037]
Further, here, the axial center line 3 of the discharge port 1c of the discharge passage 1b of the casing 1 is made to coincide with the first center line CL1 of the impeller 2, but the arrangement of pipes connected to the discharge port 1c. May be set so as to substantially coincide with the second center line CL2 of the impeller 2.
[0038]
【Example】
Hereinafter, the present invention will be described in detail based on examples.
〔Example〕
As shown in FIG. 1, the centrifugal blower BB includes a spiral casing 1 and an impeller 2 installed in a spiral chamber 1 a of the casing 1. The axial centerline 3 of the discharge port 1c of the discharge passage 1b of the casing 1 substantially coincides with the vertical centerline CL1 of the impeller 2. The speed reducer 4 is provided near the discharge port 1c.
[0039]
In the centrifugal blower BB, the height H of the discharge port 1c from the second center line CL2 of the impeller 2 to the inside diameter D of the discharge port 1a of the casing 1 is 0.95D, and the radius of curvature R of the reduction section 4 is R. = 0.07D, the height H2 of the reduction section 4 = 0.07D, and the spread angle δ1 of the discharge passage 1b = 28 °.
[Comparative Example 1]
In Comparative Example 1, as shown in FIG. 5, the center of the casing in the same direction as the axial direction of the discharge port 10a passes through the axial centerline 12 of the discharge port 10a of the casing 10 and the axis of the impeller 11 with respect to the embodiment. The line (hereinafter referred to as a vertical center line) CL1 is parallel to a predetermined distance, is not provided with the deceleration section, and has an inner diameter D2 (approximately 0.85D) of the discharge port 10a of the casing 10. ) Is different from the height H3 = 0.92D2 from the second center line CL2 of the impeller 11 to the discharge port 10a. Others are the same as the embodiment.
[Comparative Example 2]
As shown in FIG. 7B, the comparative example 2 is different from the embodiment in that the comparative example 2 does not include the deceleration unit. Therefore, as shown by the two-dot chain line in FIG. 1C, the spread angle δ1 of the discharge passage 1b is widened from 28 ° to 30 °. Others are the same as the embodiment.
[Evaluation of properties]
Using the centrifugal blowers of the above Examples, Comparative Examples 1 and 2, the performance of the centrifugal blowers was measured and evaluated. The result is shown in FIG. In the figure, symbols L1, L2, and L3 are performance curves corresponding to Comparative Example 1, Comparative Example 2, and Example, respectively.
[0040]
As shown in FIG. 3, when comparing the comparative example 1 (performance curve L1) and the example (performance curve L3), it can be seen that the performance of the example is not significantly lower than that of the comparative example 1. Thus, it can be said that the example has the same performance as the comparative example 1. Further, as described above, the centrifugal blower of the present embodiment does not need to prepare many types corresponding to the arrangement of the pipes connected to the discharge port 10a, unlike the centrifugal blower of Comparative Example 1. More specifically, as shown in FIG. 4, the number of completed centrifugal blowers of the present embodiment can be reduced from six types to three types.
[0041]
On the other hand, in Comparative Example 2, the number of types of centrifugal blowers can be reduced as in the example, but the performance of the centrifugal blowers is reduced as shown in FIG. In particular, in the high air volume region of the centrifugal blower, the static pressure of Comparative Example 2 (performance curve L2) is significantly lower than that of the example (performance curve L3), and a large pressure loss occurs. This is because the fluid flowing through the discharge passage 1b is not sufficiently decelerated because the speed reduction portion 4 is not provided in the discharge passage 1b, and the spread angle δ1 of the discharge passage 1b is increased from 28 ° to 30 °. This is considered to be due to the fact that fluid separation and the like easily occur on the inner surface of the discharge passage 1b. Thus, it is understood that the provision of the speed reducer 4 in the discharge passage 1b of the centrifugal blower BB is effective in reducing the pressure loss.
[0042]
The above-described embodiment is an example, and various changes can be made without departing from the spirit of the present invention, and the present invention is not limited to the above-described embodiment.
[0043]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, a kind can be reduced compared with the conventional centrifugal blower, without deteriorating the performance of a centrifugal blower. As a result, the productivity of the centrifugal blower is improved, and inventory management is also facilitated.
[Brief description of the drawings]
FIG. 1 is a diagram showing a basic configuration example of a centrifugal blower according to an embodiment of the present invention, wherein (a) is a front view, (b) is a plan view, and (c) is an AA line of (b). It is a partial sectional view.
FIG. 2 is a partial sectional view taken along line X1-X1 to X4-X4 of FIG.
FIG. 3 is a graph showing a relationship between a flow rate of a centrifugal blower and a static pressure.
FIG. 4 is a diagram showing types of completed centrifugal blowers according to one embodiment of the present invention.
FIG. 5 is a diagram showing a configuration of a conventional centrifugal blower having a spiral casing.
FIG. 6 is a view showing the types of finished products of the conventional centrifugal blower.
FIG. 7 is a diagram showing the performance of a conventional centrifugal blower.
FIG. 8 is a diagram showing the performance of a conventional centrifugal blower.
[Explanation of symbols]
Reference Signs List 1 casing 1b discharge passage 2 impeller 3 axial center line of discharge port of discharge passage 4 reduction unit BB centrifugal blower CL1 first center line of impeller CL2 second center line of impeller

Claims (3)

A centrifugal blower having a built-in impeller in a spiral casing,
A discharge passage provided in the casing such that an axial center line of the discharge port passes through an axis of the impeller;
A deceleration section formed in the vicinity of the discharge port of the discharge passage so that the flow path is curved outward so as to gradually expand the fluid in the discharge direction, and for efficiently decelerating the fluid flowing inside the discharge passage. And a centrifugal blower. 2. The centrifugal blower according to claim 1, wherein the deceleration portions are formed on both sides in the same direction as the axial direction of the impeller, near the discharge port of the discharge passage. 3. 3. The centrifugal blower according to claim 1, wherein the deceleration portion is formed such that a radius of curvature of a curved portion is 5 to 20% of an inner diameter of a discharge port of the discharge passage. 4.

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