JP2004339997A - Blower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blower capable of reducing noise without lowering largely breathing efficiency. <P>SOLUTION: The case 12 of the blower 10 is formed with an air discharging flow path 19 protruding, from an end of an introducing guiding path 18 formed so as to go around along an inside wall, to the tangential direction of a centrifugal fan 11. In a portion at a rotational direction side of the centrifugal fan 11 in the bottom of the air discharging flow path 19, an outside wall of the case 12 is formed into a tongue-shaped portion 20 that is formed nearly U-shaped. When the position of the tongue-shaped portion 20 is defined as position 0°, a nearly triangular shielding piece 21 is provided in a manner protruding from the opening edge of an inlet 17 at a shifted position by 90°away from the defined position of 0°in the rotating direction of the centrifugal fan 11 with a rotating shaft C defined as the center, and in a manner protruding from a position within the range of±15°of the shifted position, to the rotating shaft C (the center of the inlet 17). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a blower, and more particularly, to a reduction in noise of a blower fan used in a vehicle air conditioner or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a blower used in a vehicle air conditioner or the like, as shown in FIG. 11, a centrifugal fan 1 for blowing air taken in from a rotation axis direction to a radially outward direction, and the centrifugal fan 1 are housed. 1 is provided with a suction port 2 for introducing air, and a cylindrical container-like case 4 in which an air flow path 3 through which air blown from the centrifugal fan 1 flows is formed along an inner wall (for example, Patent Reference 1). The case 4 is formed with a cylindrical discharge port 5 extending outward from the air flow path 3 toward the tangential direction of the outer periphery of the case, and the air flow path 3 is substantially swirled toward the discharge port. It has a shape. In particular, the case 4 has a tongue-shaped boundary portion (hereinafter, referred to as a tongue portion) in which a gap between the discharge port 5 and the case 4 adjacent to the discharge port 5 on the fan rotation direction side is narrow. A projecting wall 6 projecting toward the inside of the case is formed over the spiral end side (near the discharge portion). By forming the protruding wall 6, noise of the blower is reduced.
[0003]
Further, as another blower, there is known a blower in which a part of a suction port is covered with a closing plate in the vicinity of a tongue where a gap between an outer circumferential surface of a centrifugal fan and an inner circumferential surface of a case is narrowed near a discharge port. (For example, see Patent Documents 2 and 3).
[0004]
[Patent Document 1]
JP 2001-50193 A (Page 2, FIG. 2)
[0005]
[Patent Document 2]
JP 2001-82394 A (Page 3, FIG. 1)
[0006]
[Patent Document 3]
JP-A-2001-140793 (page 3, FIG. 3)
[0007]
[Problems to be solved by the invention]
However, in the above-described related art, in any case, the noise generation location in the blower is not specified. In the blower described in Patent Document 1, although the flow of the air blown to the discharge port 5 is controlled by the protruding wall, noise caused by the air flow sucked from the suction port 2 in the rotation axis direction can be suppressed. Can not. In Patent Document 2, since the suction port is closed with a closing plate at a spread angle of 90 ° or more in the vicinity of the tongue, the flow rate decreases due to a suction obstacle, the flow is deviated, and the suction area decreases. However, there is a problem that noise increases due to the increase in the flow velocity accompanying the above. Further, in Patent Document 3, since the air control plate protrudes inward from the suction port of the case, the centrifugal fan facing the air control plate does not substantially contribute to the suction of air. There is a problem that the intake efficiency of the centrifugal fan is reduced.
[0008]
Therefore, an object of the present invention is to provide a blower that can achieve low noise without significantly lowering the intake efficiency.
[0009]
[Means for Solving the Problems]
The invention according to claim 1, wherein a plurality of blades are arranged so as to surround the rotating shaft in parallel with the rotating shaft, and a centrifugal fan that sucks air from the axial direction of the rotating shaft and blows out radially outward; The centrifugal fan is housed, and a suction port for sucking air from one side of the rotating shaft of the centrifugal fan is formed, and the air blown out of the centrifugal fan is moved along the inner wall surface of the centrifugal fan, A case having an introduction guide path for guiding to a tangentially protruding air discharge flow path, and at an opening edge of the suction port, an end position of the air discharge flow path on the rotation direction side of the centrifugal fan, When the tongue is set to 0 ° with respect to the line connecting the rotation axis, a sector shape forming an angle of ± 22.5 ° from a position forming 90 ° toward the downstream side in the rotation direction with the rotation axis as the rotation center. Within the range of the opening edge Toward serial rotary shaft, characterized in that the formation of the shielding piece extending.
[0010]
According to the first aspect of the present invention, with respect to a line connecting an end position of the air discharge flow path on the rotation direction side of the centrifugal fan and the rotation axis, the rotation axis is the rotation center and the rotation direction downstream side. The main sound source located near the “90 ° position”, that is, at the position of the wing row existing at the position where the local fast flow interferes with the wing row, by forming the shielding piece at 90 ° The noise can be suppressed by blocking the air with the shielding piece. In addition, a shielding piece extending toward the rotation axis is formed within a sector shape forming an angle of ± 22.5 ° from the “90 ° position”, thereby suppressing an increase in static pressure while suppressing noise. Can be reduced.
[0011]
The invention according to claim 2 is the blower according to claim 1, wherein the shielding piece is within a deployment angle of 45 ° with the rotation axis as a vertex.
[0012]
The invention according to claim 3 is the blower according to claim 1 or 2, wherein the shielding piece is inclined in a suction direction of the suction port from an opening edge of the suction port toward a tip end side. It is characterized by being provided.
[0013]
According to a fourth aspect of the present invention, in the blower according to the third aspect, the distal end of the shielding piece sucks a distance of 1/10 or less of an outer diameter of the centrifugal fan from an opening end of the suction port. It is characterized by being located on the direction side.
[0014]
The invention according to claim 5 is the blower according to any one of claims 1 to 4, wherein the shielding piece is integrally formed with a rib for preventing bending of the shielding piece. It is characterized by having.
[0015]
【The invention's effect】
According to the first aspect of the present invention, since the shielding piece is formed at a position where the suction flow is locally high at a position 90 ° from the center position of the tongue radius, the scroll is stable from here to the tongue. The main flow near the outlet is also stabilized, so that the fluctuating noise can be eliminated and the noise level can be reduced.
[0016]
According to the second aspect of the present invention, by suppressing the deployment angle to within 45 °, it is possible to secure the flow rate of the intake air.
[0017]
According to the third and fourth aspects of the present invention, it is possible to improve the air flow by setting the shielding piece obliquely.
[0018]
According to the fifth aspect of the invention, by forming the rib integrally with the shielding piece, it is possible to prevent the durability of the shielding piece and prevent vibration.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, details of a blower according to the present invention will be described based on an embodiment shown in the drawings. The blower described here is used, for example, in a vehicle air conditioner.
[0020]
(Embodiment)
1 to 4 show a blower according to a first embodiment of the present invention. FIG. 1 is a front view showing a blower of the present embodiment, FIG. 2 is a perspective view showing a centrifugal fan, FIG. 3 is a longitudinal sectional view of the blower, and FIG. 4 is a sectional view taken along line AA of FIG.
[0021]
As shown in FIGS. 1 and 2, the blower 10 according to the present embodiment includes a cylindrical centrifugal fan 11, a substantially cylindrical case 12, and a motor 13 that drives the centrifugal fan 11 to rotate. Have been.
[0022]
As shown in FIGS. 2 and 4, the centrifugal fan 11 has a rotating plate 14 having a substantially circular shape at the center thereof and a large number of blades erected on the peripheral edge of the rotating substrate 14 at equal intervals. 15 and an annular blade connection plate 16 formed integrally with the upper ends of these many blades 15 to form a centrifugal multi-blade fan. Note that a shaft insertion opening 14A into which a drive shaft 13A of the motor 13 fixed to the case 12 is inserted and fixed is formed in the center of the rotating substrate 14.
[0023]
As shown in the vertical sectional view of FIG. 3, the case 12 houses the centrifugal fan 11 and has a circular inlet 17 formed on one side surface of the rotation axis C of the centrifugal fan 11. In addition, the case 12 is formed with an introduction guide path 18 that circulates one turn in a spiral shape from a narrow flow path to a gradually wide flow path so as to surround the stored centrifugal fan 11. Further, the case 12 is formed with an air discharge flow path 19 protruding from the end of the introduction guide path 18 in the tangential direction of the centrifugal fan 11. The intersection of the flow path wall 19 a of the air discharge flow path 19 and the outer wall of the case 12 is connected by an arc to form a tongue 20. The radius of the arc of the tongue 20 (the tongue radius r) is a range represented by the formula 0.04 <r / D <0.06 when the fan outer diameter D is used. In this embodiment, since the tongue radius is r = 0.05D (fan outer diameter is 160 mm), it is formed with r = 8 mm.
[0024]
When the center position of the tongue portion radius r of the tongue portion 20 is set to 0 °, the 90 ° from the opening edge of the suction port 17 at a position shifted by 90 ° in the rotation direction of the centrifugal fan 11 about the rotation axis C. A substantially triangular shielding piece 21 protrudes from a position within a range of ± 15 ° toward the rotation axis C (the center of the suction port 17). The shielding piece 21 affects the air sucked in the direction of the rotation axis C toward the suction port 17 and also affects the airflow on the centrifugal fan 11 side inside the shielding piece 21.
[0025]
[Blower noise generation mechanism]
Here, a mechanism of noise generation of the blower will be described. In this description, a blower 10A having a general structure without the shielding piece 21 is used as the blower. This is because the structure of the blower according to the present invention can be realized as a noise countermeasure by knowing such a noise generation mechanism of the blower 10A. The configuration of the blower 10A is the same as that of the above-described blower 10 of the present embodiment except that the blower 10A does not include the shielding piece 21. Therefore, each part will be described with the same reference numeral.
[0026]
First, when the blower 10A is rotationally driven, the outlet pressure in the air discharge flow path 19 increases, so that a part of the air flow from the centrifugal fan 11 is pushed back, and a part of the air flow from the tongue 20 (0 ° position). While re-entering the row of wings 15, the recirculating flow leaking into the introduction guideway 18 again through the row of wings 15 downstream thereof becomes a universal flow (see FIG. 6).
[0027]
Then, in the tongue portion 20, airflow from above cannot flow in, and as shown in FIG. 6, stagnation occurs, forming a very unstable region. The flow released from the stagnation starts to flow into the scroll strongly and stably from around the 90 ° position. In the stagnation portion, the flow stagnates and violently oscillates depending on whether it flows to the exit side or the scroll side with the tongue as a boundary. This oscillation also swings the exit main flow, and the oscillating main flow and the rotating impeller Causes collision noise to generate loud noise. When the main flow and the cascade interfere with each other, noise is generated from the blade surface at a blade passing frequency called blade passing noise. In general, it has been confirmed that the noise of a blower is generated at the sixth power of the flow velocity. From the basic theory of fluid noise, the noise proportional to the sixth power is generated by the generated vortex acting on nearby walls and amplified. In the case of the impeller, the blade surface is the main occurrence site. At this time, if the main flow is oscillating, not only the blade passing frequency but also various noises are generated from the wing surface at the oscillating cycle. In fact, it was confirmed by sound source exploration that the cascade near the outlet had unstable and loud noise.Similarly, the flow near the outlet was also fluctuating. ing.
[0028]
The present invention is configured based on the noise generation mechanism of the blower as described above. That is, as in the blower 10 of the present embodiment described above, the shielding piece 21 is formed at a portion where the suction flow is locally high at the “90 ° position”, so that it is stable from here to the tongue. As a result, stagnation is reduced and stabilized, and as a result, the main flow near the outlet is also stabilized, so that fluctuating noise is eliminated and the noise level can be reduced. In an actual experiment, as described in the above description of the mechanism, the noise could be reduced by disposing the shielding piece 21 near the “90 ° position”.
[0029]
FIG. 7 is a graph showing the result of examining the noise suppression effect when the shielding piece 21 formed in the present embodiment is provided at each position of the suction port 17. In the graph of FIG. 7, the horizontal axis indicates the angular position in the rotation direction of the centrifugal fan 11 from the tongue (position of 0 °), and the vertical axis indicates the noise level (dB). The rotation condition of the centrifugal fan 11 was set so that the rotation speed was 2200 rpm when there was no load.
[0030]
It can be seen from the graph of FIG. 7 that the noise level can be significantly reduced by disposing the shielding piece 21 at a position of 90 °. In addition, it can be seen from the figure that the noise level is reduced even if the shielding piece 21 is arranged at the position of 0 °.
[0031]
Based on the results shown in FIG. 7, in the blower according to the present invention, the shielding piece 21 is arranged and formed at a position 90 ° in the rotation direction of the centrifugal fan 11 from the tongue (0 ° position) at the suction port 17. By doing so, the noise level of the blower 10 can be reduced. In addition, from the result shown in FIG. 7, since the noise level can be reduced even if the shielding piece 21 is arranged at the position of 0 °, the shielding piece is also placed at the position of 0 ° in addition to the position of 90 °. An additional configuration may be used. However, since the noise level can be significantly reduced by disposing the shielding piece 21 at the position of 90 °, considering that the ventilation resistance at the suction port 17 is increased, the shielding position at the position of 0 ° is considered. The necessity of providing a piece is judged to be low.
[0032]
Next, a description will be given of the noise suppression effect of the blower 10 according to the present embodiment by the development angle of the shielding piece 21 (the spread angle of the shielding piece 21 as viewed from the rotation axis of the centrifugal fan 11: see FIG. 3). FIG. 8 is a graph confirming the noise suppressing effect and the static pressure increasing effect of the centrifugal fan 11 depending on the deployment angle of the shielding piece 21. From this graph, it can be seen that if the deployment angle of the shielding piece 21 is too large, the noise will rather increase and the performance of the centrifugal fan 11 will also decrease. Here, it can be understood that, in order to reduce the noise by 5% or more with respect to the current product as shown in FIGS. . That is, in order to reduce noise while minimizing performance degradation, it is necessary to keep the development angle within 45 °.
[0033]
(Other embodiments)
As described above, the embodiments of the present invention have been described. However, it should not be understood that the description and drawings constituting a part of the disclosure of the above embodiments limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.
[0034]
For example, in the above-described embodiment, the shielding piece 21 is protruded toward the center so as to be parallel to the opening surface of the suction port 17. However, as shown in FIG. (The centrifugal fan 11 side) may be formed, and a reinforcing rib 21 </ b> B may be integrally formed in the center of the upper surface in the radial direction of the suction port 17. It is preferable that the distance d from the opening surface of the suction port 17 of the distal end portion of the shielding piece 21A is located on the suction direction side by a distance equal to or less than 1/10 of the outer diameter of the centrifugal fan 11. In this manner, by inclining the shielding piece 21A toward the centrifugal fan 11, the resistance of the drawn airflow can be reduced.
[0035]
In the above-described embodiment, the shielding piece 21 is formed in a fan shape (substantially triangular) toward the rotation axis of the centrifugal fan 11, but may be formed in a substantially trapezoidal shape like a shielding piece 21C shown in FIG. Of course.
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of a blower according to the present invention.
FIG. 2 is a perspective view showing a centrifugal fan of the blower according to the present embodiment.
FIG. 3 is a longitudinal sectional view of the blower according to the present embodiment.
FIG. 4 is a sectional view taken along line AA of FIG. 1;
FIG. 5 is a perspective view showing an air flow of a current product.
FIG. 6 is a front view showing an air flow of a current product.
FIG. 7 is a graph showing a noise suppression effect of a shielding piece in the blower according to the present embodiment.
FIG. 8 is a graph showing a relationship between a development angle of a shielding piece and a noise amount in the blower according to the present embodiment.
FIG. 9 is a main part perspective view showing another embodiment of the blower according to the present invention.
FIG. 10 is a main part perspective view showing another embodiment of the blower according to the present invention.
FIG. 11 is a front view showing a configuration of a conventional blower.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Blower 11 Centrifugal fan 12 Case 13 Motor 15 Blade 17 Inlet 18 Induction guideway 19 Air discharge flow path 20 Tongue (0 ° position)
21, 21A, 21C Shielding piece 21B Reinforcing rib

Claims (5)

A plurality of wings (15) are arranged so as to be parallel to the rotation axis (C) and surround the rotation axis (C), and to inhale air from the axial direction of the rotation axis (C) and to blow out radially outward. A centrifugal fan (11), and a suction port (17) that houses the centrifugal fan (11) and that sucks air from one side of the rotating shaft (C) of the centrifugal fan (11) are formed; A case having an introduction guideway (18) for guiding air blown out from the centrifugal fan (11) along an inner wall surface to an air discharge flow path (19) protruding in a tangential direction of the centrifugal fan (11). (12)
With respect to a line connecting an end position of the air discharge flow path (19) on the rotation direction side of the centrifugal fan (11) and the rotation axis (C) at an opening edge of the suction port (17), Assuming that the tongue is at 0 °, the opening edge is within a fan-shaped range at an angle of ± 22.5 ° from a position at 90 ° to the downstream side in the rotation direction about the rotation axis (C) as the center of rotation. A blower (10), characterized in that a shielding piece (21) extending from the to the rotation axis (C) is formed. The blower (10) according to claim 1, wherein:
The blower (10), wherein the shielding piece (21) has a deployment angle of 45 ° or less with the rotation axis as a vertex. A blower (10) according to claim 1 or claim 2,
The blower (10), wherein the shielding piece (21A) is provided to be inclined in a suction direction of the suction port (17) from an opening edge of the suction port (17) toward a tip end side. The blower (10) according to claim 3, wherein:
The distal end of the shielding piece (21A) is located on the suction direction side at a distance of 1/10 or less of the outer diameter of the centrifugal fan (11) from the open end of the suction port (17). Blower (10). A blower (10) according to any of the preceding claims, wherein:
A blower (10), wherein a rib (21B) for preventing bending of the shielding piece (21A) is formed integrally with the shielding piece (21A).

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