JP4590167B2 - Centrifugal blower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a centrifugal blower including a spiral casing used for air conditioning equipment or ventilation equipment.
[0002]
[Background Art and Problems to be Solved by the Invention]
FIG. 5 is a diagram illustrating a configuration of a centrifugal blower including a conventional spiral casing. The centrifugal blower B includes a casing 10 and an impeller 11 built in the spiral chamber of the casing 10. The axial center line 12 of the discharge port 10a of the casing 10 and the center line (hereinafter referred to as the first 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 have a predetermined distance. They are parallel to each other.
[0003]
In 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, but the bending of the pipe When the direction is opposite to the rotation direction of the impeller 11, the fluid in the fast-flowing portion is affected, and a large pressure loss is generated in the bent portion of the pipe. Thereby, there is a problem that a predetermined air volume cannot be obtained.
[0004]
In contrast, conventionally, as shown in FIGS. 6A and 6B, even when the fluid is discharged in the same direction (upward in the figure), the curve of the pipe connected to the discharge port 10a of the casing 10 is bent. Two types of impellers 11 having different rotation directions (clockwise or counterclockwise) and casings 10 corresponding thereto are prepared corresponding to the directions.
[0005]
The casing 10 is installed on the base 14 of the centrifugal blower B together with a motor 15 that drives 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 shaft of the discharge port 10a. The direction center line 12 is installed on the base 14 so as to substantially coincide with each fluid discharge direction 13 (upward, leftward, and rightward in the figure). However, since the shape of the part attached to the base 14 of the casing 10 is different, it is necessary to prepare three types of bases 14 corresponding to the fluid discharge direction 13.
[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 an axial center line 12 of the discharge port 10a. Are 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 described above.
[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 the productivity of the centrifugal blower B is deteriorated and inventory management is complicated.
[0008]
Therefore, in order to cope with this, for example, as shown in FIG. 7A, the casing 10 of the conventional centrifugal blower B indicated by a two-dot chain line is arranged such that the axial center line 12 of the discharge port 10a has the impeller. 11 is arranged on the base 14 so as to approach the first center line CL1. Further, the elbow joint 16 is attached to the discharge port 10a of the casing 10 so 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-described fluid having a fast flow approaches the vicinity of the center of the new discharge port 16a, and even if the pipe connected to the discharge port 16a is bent in the same direction as the rotation direction of the impeller 11. Even when bent in the opposite direction, fluid peeling or the like hardly occurs 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 than the conventional case.
[0011]
On the other hand, in the centrifugal blower B2 disclosed in Patent Document 1, the casing 10 has a first center line of the impeller 11 in which the axial center line 12 of the discharge port 10a is, as shown in FIG. It is formed in a shape such that a portion 17 in the vicinity of the discharge port 10a of the casing 10 is scraped off so as to approach the CL1 and face in the same direction. As a result, the axial centerline 12a of the newly formed discharge port 10b approaches the first centerline CL1 of the impeller 11 without providing the elbow joint 16 at the discharge port 10a of the casing 10 as described above. Look in the same direction.
[0012]
Thereby, as above-mentioned, centrifugal blower B2 does not become large. However, since the diffuser portion 18 of the centrifugal blower B2 is shortened, the flow velocity in the portion 18 cannot be sufficiently reduced, and there is a problem that the pressure loss of the portion 18 increases and the performance of the centrifugal blower B2 is lowered.
[0013]
Specifically, as shown in FIG. 8, the flow rate-static pressure curve L2 of the centrifugal blower shown in FIG. 7B is the same as the flow rate-static pressure curve L1 of the conventional centrifugal blower. In contrast, the static pressure shifts in the direction of decreasing. 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 portion 18, it is possible to suppress an increase in pressure loss, but there is a problem that the centrifugal fan becomes larger as described above.
[0015]
Then, this invention was made | formed in order to solve the above problem, and it aims at providing the centrifugal blower which can reduce a kind compared with the conventional centrifugal blower, without reducing performance. .
[0016]
[Patent Document 1]
JP 11-294393 A (FIG. 1)
[0017]
[Means for Solving the Problems]
The present invention is a centrifugal blower incorporating an impeller in a spiral casing, the discharge passage provided in the casing such that the axial center line of the discharge port passes through the axis of the impeller, Near each discharge port of the discharge passage and on both sides in the same direction as the axial direction of the impeller, the flow path is formed to curve outward so that the fluid gradually expands along the discharge direction. And a speed reducer for efficiently decelerating the fluid flowing inside. The discharge passage communicates the inclined portion formed by expanding at a predetermined angle toward the width direction of the casing, which is the axial direction of the impeller, and the inclined portion and the speed reduction portion. And a communication portion that is curved inward in the radial direction.
[0018]
According to this configuration, at the discharge port of the discharge passage of the centrifugal blower, a fast-flowing fluid can be brought close to the central portion, and the fluid flowing therein can be efficiently decelerated. Therefore, even if the pipe connected to the discharge passage is bent in the same direction as the rotation direction of the impeller or bent in the opposite direction, fluid separation or the like hardly occurs at the bent portion, and no large pressure loss occurs. . Thereby, the rotation direction of the impeller of a centrifugal blower can be made into one type from the conventional two types, without reducing the performance of a centrifugal blower.
[0020]
In general, the inner surfaces of both sides in the radial direction of the impeller in the vicinity of the discharge port of the discharge passage of the centrifugal blower are formed along the spiral shape of the casing, so that no large pressure loss occurs in this portion. On the other hand, the inner surface of the both sides in the axial direction of the impeller near the discharge port of the discharge passage of the centrifugal blower has a width dimension in the same direction as the axial direction of the impeller of the discharge passage of the centrifugal blower, Since the casing is larger than the width dimension in the same direction as the axial direction of the impeller, the separation distance between both inner surfaces is formed so as to gradually increase toward the discharge port. Therefore, the fluid flowing in the discharge passage may be peeled off 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 deceleration portion is provided in this portion. Thereby, since the increase in pressure loss can be prevented, it becomes possible to prevent the performance of a centrifugal blower from deteriorating.
[0021]
Further, it is desirable that the speed reducing portion is formed so that the curvature radius 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 deceleration unit. Thereby, since the increase in pressure loss can be prevented, it becomes possible to prevent the performance of a centrifugal blower from deteriorating. When the radius of curvature of the curved portion of the speed reducing portion is less than 5% of the inner diameter of the discharge port of the discharge passage, the speed reducing portion is too short to efficiently decelerate the fluid. Further, when the curvature radius 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]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a diagram illustrating 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 portion of (b). It is sectional drawing. FIG. 2 is a partial cross-sectional view taken along line X1-X1 to X4-X4 of 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 finished products of the centrifugal blower according to the 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 1 a of the casing 1. The casing 1 includes 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 flow passage cross section of the spiral chamber 1a is substantially rectangular, and the flow passage cross section gradually changes to a circular shape from the spiral chamber 1a through the flow passage 1b, and the discharge passage 1b discharges. The exit 1c is circular.
[0026]
The axial center line 3 of the discharge port 1c passes through the axis of the impeller 2 and substantially coincides with a center line CL1 (hereinafter referred to as a first center line) CL1 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 with a fast flow can be brought close to the central portion of the discharge port 1c of the centrifugal blower BB. As a result, even if a pipe (not shown) connected to the discharge port 1c is bent in the same direction as the rotation direction of the impeller 2 or bent in the opposite direction, fluid separation or the like hardly occurs at this 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. 1C, the discharge passage 1b includes a speed reducing portion 4 for efficiently decelerating the fluid flowing inside, and the width direction of the casing 1 in the axial direction of the discharge passage 1b. (In the same direction as the axial direction of the impeller 2; see the symbol W in FIG. 1B.) And a connecting portion 6 that is curved at a radius of curvature 2R inward in the radial direction 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 speed reducing portion 4 is disposed on both sides in the width direction of the casing 1 (shaded portions in FIG. 1B) in the vicinity of the discharge port 1c of the discharge passage 1b of the centrifugal blower BB. Is formed. As shown in FIG. 1C, the speed reduction portion 4 has a predetermined radius of curvature R symmetrically with respect to the axial center line 3 of the discharge port 1c in the cross-sectional view taken along the line AA in FIG. And curved outward in the radial direction.
[0030]
Further, as shown in FIGS. 2 (a) to 2 (e), the curvature radius of the curved deceleration portion 4 is X1-X1, X2-X2, AA, X3-X3, X4- in FIG. 1 (b). They are R1, R2, R, R3, and R4, respectively, in the X4 sectional view. These have a relationship of R1>R2> R and R4>R3> R. That is, as the position of the cross-sectional view moves away from the center of the discharge port 1c to the left and right (direction perpendicular to the width direction of the casing 1), the radius of curvature of the speed reduction unit 4 corresponding to the position gradually increases. And the right-and-left end of this deceleration part 4 is continued to the site | part 7 except the deceleration part 4 of the discharge passage 1b vicinity of the discharge outlet 1c, respectively.
[0031]
Here, it is desirable that the curvature radius R of the speed reducing portion 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 part 4 is less than 5% of the inner diameter D of the discharge port 1c of the discharge passage 1b, the speed reduction part 4 is too short to efficiently reduce the fluid. Moreover, it is because the casing 1 becomes large when the curvature radius R of the deceleration part 4 exceeds 20% of the internal diameter D of the discharge outlet 1c. Further, it is desirable to set the axial height H2 of the speed reducing portion 4 to 0.05D to 0.2D corresponding to the radius of curvature R of the speed reducing portion 4.
[0032]
Note that the curved 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]
Since the fluid flowing through the speed reduction unit 4 is efficiently decelerated, the axial distance of the discharge passage 1b necessary for decelerating the fluid can be set smaller than in the prior art. In other words, when the speed reduction part 4 is not provided near the discharge port 1c, it is necessary to increase the distance.
[0034]
More specifically, the height H from the center line (hereinafter referred to as the 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. It can be set to 1.5 times or less of D.
[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 1 c may be the same as the inner diameter D1 of the suction port 8 of the casing 1. Thereby, the kind of piping connected to these can also be unified.
[0037]
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 piping connected to the discharge port 1c is arranged. Accordingly, it 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 center line 3 of the discharge port 1 c of the discharge passage 1 b of the casing 1 substantially coincides with the vertical center line CL 1 of the impeller 2. A deceleration unit 4 is provided in the vicinity of the discharge port 1c.
[0039]
In this centrifugal blower BB, the height H = 0.95D of the discharge port 1c from the second center line CL2 of the impeller 2 with respect to the inner diameter D of the discharge port 1a of the casing 1, and the radius of curvature R of the speed reduction unit 4 = 0.07D, the height H2 of the deceleration unit 4 = 0.07D, and the spread angle δ1 of the discharge passage 1b is set to 28 °.
[Comparative Example 1]
As shown in FIG. 5, the first comparative example has a center in the same direction as the axial direction of the discharge port 10 a through the axial center line 12 of the discharge port 10 a of the casing 10 and the axis of the impeller 11. A line (hereinafter referred to as a vertical center line) CL1 parallel to each other at a predetermined distance, not including the speed reduction portion, and an inner diameter D2 (approximately 0.85D) of the discharge port 10a of the casing 10 ), The height H3 from the second center line CL2 of the impeller 11 to the discharge port 10a is set to 0.92D2. Others are the same as the embodiment.
[Comparative Example 2]
As shown in FIG. 7B, the second comparative example is different from the first embodiment in that the speed reduction portion is not provided. Therefore, as shown by a two-dot chain line in FIG. 1C, the above-described 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 blower 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 Comparative Example 1 (performance curve L1) is compared with the Example (performance curve L3), it can be seen that the performance of the Example is not significantly reduced compared to Comparative Example 1. Thereby, it can be said that an Example is equivalent to the performance of the comparative example 1. Moreover, as described above, the centrifugal blower of the present embodiment does not need to be prepared in many types corresponding to the arrangement of the pipes connected to the discharge port 10a, unlike the centrifugal blower of Comparative Example 1. Specifically, as shown in FIG. 4, the types of finished products of the centrifugal blower of the present embodiment can be reduced from the conventional six types to three types.
[0041]
On the other hand, Comparative Example 2 can reduce the type of centrifugal blower as in the example, but the performance of the centrifugal blower is degraded 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 greatly reduced with respect to the example (performance curve L3), resulting in a large pressure loss. This is because the above-described discharge passage 1b is not provided with the speed reducing portion 4, so that the fluid flowing therein is not sufficiently decelerated, and the spread angle δ1 of the discharge passage 1b is increased from 28 ° to 30 °. Therefore, it is considered that fluid separation or the like is likely to occur on the inner surface of the discharge passage 1b. Thereby, it turns out that providing the deceleration part 4 in the discharge channel | path 1b of centrifugal blower BB is effective in reducing a pressure loss.
[0042]
The above-described embodiment is an example, and various modifications are possible without departing from the spirit of the present invention. The present invention is not limited to the above-described embodiment.
[0043]
【The invention's effect】
According to this invention, a kind can be reduced compared with the conventional centrifugal blower, without reducing the performance of a centrifugal blower. As a result, the productivity of the centrifugal fan is improved and inventory management is 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, where (a) is a front view, (b) is a plan view, and (c) is an AA line in (b). It is a fragmentary sectional view.
2 is a partial cross-sectional view taken along line X1-X1 to X4-X4 of FIG.
FIG. 3 is a graph showing the relationship between the air volume of a centrifugal blower and static pressure.
FIG. 4 is a view showing types of finished products of the centrifugal blower according to the embodiment of the present invention.
FIG. 5 is a diagram showing a configuration of a centrifugal blower including a conventional spiral casing.
FIG. 6 is a view showing types of finished products of a 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]
DESCRIPTION OF SYMBOLS 1 Casing 1b Discharge channel | path 2 Impeller 3 Axial direction centerline 4 of discharge port of discharge passage Deceleration part BB Centrifugal blower CL1 1st centerline CL2 of impeller 2nd centerline of impeller

Claims (3)

A centrifugal blower with a built-in impeller in a spiral casing,
A discharge passage provided in the casing such that the axial center line of the discharge port passes through the axis of the impeller;
In the vicinity of the discharge port of the discharge passage and on both sides in the same direction as the axial direction of the impeller , the flow path is formed to be curved outward so that the fluid gradually expands along the discharge direction. And a decelerating part for decelerating the fluid flowing inside,
The discharge passage is an inclined portion formed by expanding at a predetermined angle toward the width direction of the casing, which is the axial direction of the impeller, and a radial direction for connecting the inclined portion and the speed reduction portion. A centrifugal blower comprising a connecting portion that is curved inward. The centrifugal blower according to claim 1 , wherein the speed reducing portion is formed such that a curvature radius of a curved portion is 5 to 20% of an inner diameter of a discharge port of the discharge passage. The radius of curvature of the curved portion of the speed reduction portion gradually increases from the center of the discharge port in the direction perpendicular to the width direction of the casing, and both the direction of the speed reduction portion in the direction perpendicular to the width direction of the casing are increased. The centrifugal blower according to claim 1 or 2 , wherein the end is formed so as to be continuous with a portion of the discharge passage in the vicinity of the discharge port excluding the speed reduction portion.

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