JP5409557B2 - Centrifugal blower - Google Patents

Description

  The present invention relates to a centrifugal blower provided with a scroll casing for vehicle air conditioning.

A centrifugal blower used for an air conditioner for automobiles is disclosed in Patent Document 1, for example. Fig.1 (a) is sectional drawing in alignment with the axial direction of the centrifugal blower disclosed by patent document 1, (b) is a front view, (c) is a plane sectional view.
Such a conventional centrifugal blower includes a multi-blade fan 16 having a large number of blades 2, a motor 34 to which the multi-blade fan 16 is attached to an output shaft 33, and the multi-blade fan 16 accommodated therein and a large number of both. And a casing 31 having a scroll chamber 30 formed in a spiral shape on the outer peripheral side of the blade fan. The scroll chamber 30 is formed in a spiral shape in which the passage gradually expands from the tongue 1a of the casing 31 toward the discharge port. In general, the rotation center O of the multiblade fan is the center of the scroll chamber. When the tongue portion 1a is arcuate, strictly speaking, the angular position indicated by the center of curvature is the winding start portion (starting point of the spiral casing), but the tongue portion is not necessarily arcuate. The part and the winding start part will be described as being the same (the same applies to the description of the present invention below. The starting point of the circumferential angle φ described later is the center of curvature).

  The casing 31 has a suction port 13 on one surface in the axial direction of the multiblade fan 16. When the motor 34 rotates, the multiblade fan 16 sucks air from the suction port 13 into the center of the multiblade fan 16. Air is given kinetic energy (dynamic pressure) by the multi-blade fan after being sucked into the center of the multi-blade fan, and a part of the dynamic pressure is converted into static pressure in the casing while passing through the scroll chamber 30. And discharged from the discharge port.

  According to the prior art disclosed in Patent Document 1, it is possible to reduce noise accompanying backflow generation in the vicinity of the tongue 16. That is, the starting point 21a of the step 21 coincides with the winding start portion, that is, the circumferential angle φ from the winding start portion is 0 °, and the end point 21c of the step 21 has the circumferential angle φ from the winding start portion. It is 10 °. In this prior art, the end point 21c of the step 21 is defined as the starting point of the chamber part 35, and the starting point of the chamber part 35 is θ = 10 °.

  Although this conventional technique aims to reduce noise caused by the occurrence of backflow, a step for rapidly expanding the shape of the bottom surface of the scroll chamber is provided, and the scroll chamber passage is rapidly expanded. Noise reduction effect could not be obtained.

JP 2004-360497 A

  In view of the above problems, the present invention provides a centrifugal blower having a scroll casing for air conditioning of a vehicle having a low noise effect.

In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that a plurality of blades (2) are arranged at regular intervals in the circumferential direction to form an impeller, and an air intake port is provided above the impeller in the axial direction. (13) is a multi-blade fan (16) provided with a fan exit angle (A) of the multi-blade fan (16) within an angle range of 20 ° to 75 °, and When the outer diameter of the multiblade fan (16) is D, the multiblade fan (16) having an impeller width (d) within a range of 0.05 to 0.15D, and the multiblade fan (16 ) Around the winding start portion (1a), the scroll chamber (30) surrounded by a spiral casing (31) whose swirl spread angle is in the range of 2 ° to 6 °, The chamber bottom (14, 11) of the scroll chamber (30) moves downward in the axial direction along with the expansion of the spiral. In the centrifugal blower having a spiral scroll chamber (30) that gradually expands and gradually increases in flow path area from the winding start portion (1a) toward the discharge port (20), the bottom surface portion ( the winding start portion of the 14, 11) in (1a), the initial inclination angle theta ₀ toward the axially downwardly, Ri angular range der within 5.2 ° to 27.5 °, the chamber bottom portion (14 11), with the inclined sectional shape changing portion (2a) as a boundary, the steeply inclined chamber bottom surface portion (14) from the winding start portion (1a) to the inclined sectional shape changing portion (2a), and the inclined sectional shape It comprises a gently inclined chamber bottom surface portion (11) from the changing portion (2a) to the discharge port (20), and the inclined sectional shape changing portion (2a) is wound around the shaft of the impeller. The angle (φ) formed in the circumferential direction from the start portion (1a) is 30 to 60 °. And within the range of 0.2 to 0.5H with respect to the overall height H of the blades of the multi-blade fan, in the axial direction downward from the position of the bottom surface portion of the winding start portion (1a). It is in the range position (H2) .

  This improves the flow between the blades and the generation of vortices by changing the shape of the bottom surface of the chamber, and guides the reverse flow to the bottom surface of the chamber and allows the air flow causing noise to enter between the blades. Can be prevented. Moreover, since the backflow is prevented and the generation of vortices at the bottom of the room is reduced, the effects of noise reduction and fan efficiency can be obtained.

The invention of claim 2 is characterized in that, in the invention of claim 1 , the steeply inclined chamber bottom surface portion (14) is constituted by a plurality of linear cross-sectional shapes. Thereby, the change of the flow in the inclined cross-sectional shape change part can be made smoother.

The invention of claim 3 is characterized in that, in the invention of claim 1 , the steeply inclined chamber bottom surface portion (14) is formed of a curved cross-sectional shape. Thereby, the change of the flow in the inclined cross-sectional shape change part can be made smoother.

The invention of claim 4 is the invention according to any one of claims 1 to 3 , wherein the winding is performed around the shaft of the impeller from the winding start portion (1a) to the discharge port (20). The width W1 of the upper surface of the scroll chamber (30) is smaller than the width W2 of the chamber bottom surface portions (14, 11) at an arbitrary angle (φ) formed in the circumferential direction from the start portion (1a). To do. As a result, the downward flow becomes stronger, the upward flow becomes weaker, and the reverse flow does not flow between the blades. For this reason, since there is no collision with the intake air flow, noise is reduced.

  In addition, the code | symbol attached | subjected above is an example which shows a corresponding relationship with the specific embodiment as described in embodiment mentioned later.

(A) is sectional drawing which follows the axial direction of the centrifugal blower disclosed by patent document 1, (b) is a front view, (c) is a plane sectional view. It is sectional drawing of the centrifugal blower in one Embodiment of this invention. It is sectional drawing which looked at the wing | blade in one Embodiment of this invention from the axial direction of the impeller. It is explanatory drawing explaining the flow between blades in a centrifugal blower, (a) shows the suction | inhalation airflow when the chamber bottom face part of the scroll chamber 30 is not expanded below, (b) It is explanatory drawing which shows an intake air flow when a chamber bottom face part is expanded below. (A) is a graph which shows the relationship between initial inclination angle (theta) ₀ and fan efficiency in one Embodiment of this invention, (b) is a graph which shows the relationship between initial inclination angle (theta) ₀ and noise. . (A) is a graph which shows the relationship between the circumferential direction angle (phi) of the inclination cross-sectional shape change part 2a and fan efficiency in another embodiment of this invention, (b) is the circumference | surroundings of the inclination cross-section shape change part 2a. It is a graph which shows the relationship between direction angle (phi) and noise. (A) is the state of the air flow in the vicinity of the tongue when the steeply inclined chamber bottom surface portion 14 is extremely steeply inclined like a step, and (b) is the case where the steeply inclined chamber bottom surface portion 14 is the present invention. It is explanatory drawing explaining the state of the airflow of the tongue part vicinity. It is an example which displayed the relationship of (phi) and H2 of one Embodiment of this invention. (A) is a graph showing the relationship between the flow coefficient and fan efficiency, comparing the embodiment of the present invention of FIG. 8 with a comparative example, and (b) is an embodiment of the present invention of FIG. Is a graph showing the relationship between the flow coefficient and specific noise in comparison with the comparative example. (A), (b) It is explanatory drawing which shows other embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. About each embodiment, the same code | symbol is attached | subjected to the part of the same structure, and the description is abbreviate | omitted. Similarly, with respect to the prior art, parts having the same configuration are denoted by the same reference numerals and description thereof is omitted.

FIG. 2 is a cross-sectional view of a centrifugal blower according to an embodiment of the present invention.
The centrifugal blower (so-called centrifugal blower) includes a multi-blade fan 16 having a large number of blades 2, a motor 34 to which the multi-blade fan 16 is mounted, and the multi-blade fan 16 inside the casing 31, A casing 31 (hereinafter referred to as a scroll casing) having a scroll chamber 30 formed in a spiral shape is provided on the outer peripheral side of the multiblade fan.
The multi-wing fan here is also called a sirocco fan. The casing 31 having the scroll chamber 30 is called a scroll casing.

  The casing 31 has a suction port 13 on one surface in the axial direction of the multiblade fan 16. When the motor 34 rotates, the multiblade fan 16 sucks air from the suction port 13 into the center of the multiblade fan 16. In the centrifugal blower, air is given kinetic energy (dynamic pressure) by the multi-blade fan after being sucked into the center of the multi-blade fan, and a part of the dynamic pressure in the casing passes through the scroll chamber 30. It is converted into static pressure and discharged from the discharge port 20.

  In the centrifugal blower according to the embodiment of the present invention, the shape of the spiral forming the crawl casing is an angular range in which the spiral spread angle is within a range of 2 ° to 6 ° starting from the winding start portion 1a. The swirl divergence angle is described by a logarithmic spiral function or the like (for example, see paragraph 0033 of JP-A-2004-270777, paragraph 0045 of JP-A-2003-193998, etc.).

  A large number of blades 2 are arranged at regular intervals in the circumferential direction to form an impeller, and an air suction port 13 is provided above the impeller in the axial direction. The impeller refers to a portion of the multi-blade fan 16 in which a large number of blades 2 are arranged in a cylindrical shape in parallel at regular intervals in the circumferential direction. The axis of the impeller refers to the rotation center O (also referred to as the rotation axis O) of the multiblade fan 16. The electric motor 34 is a driving unit that rotationally drives the multiblade fan 16, and the electric motor 34 is fixed to a casing 31 that houses the multiblade fan 16. In FIG. 2, H indicates the overall height of the impeller (including the upper impeller ring).

  FIG. 3 is a cross-sectional view of a blade according to an embodiment of the present invention as viewed from the axial direction of the impeller. As shown in FIG. 3, the angle between the tangential direction at the outlet tip of the blade 2 and the direction perpendicular to the line connecting the outlet tip T of the blade 2 and the rotation center O is the fan outlet angle A. In one embodiment of the present invention, the fan exit angle A is in the range of 20 ° to 75 °. The distance connecting the outlet tip T of the blade 2 and the rotation center O indicates the outer diameter D of the multiblade fan 16. The impeller width d is a difference in locus radius between the outlet tip T and the inner tip T ′ of the blade 2. In one embodiment of the present invention, the impeller width d is in the range of 0.05 to 0.15 D, where D is the outer diameter of the multiblade fan 16.

  The casing 31 is formed in a substantially spiral shape so that the rotation axis O of the multiblade fan 16 is positioned on the center axis L of the scroll chamber. A suction port 13 for introducing air is formed in one end of the casing 31 in the axial direction of the rotary shaft O (on the opposite side to the motor 34, here, upward). Is provided with a bell mouth for smoothly guiding the intake air to the multi-blade fan 16.

  Until now, as a cause of noise in the centrifugal blower, interference between the backflow air and the intake air flow generated in the vicinity of the winding start portion is known in the scroll casing. In the present invention, by studying the reverse flow between the blades in detail, the inventors have focused on the fact that the noise generation source accompanying the reverse flow is mainly in the flow between the blades. 4A and 4B are explanatory views for explaining the flow between the blades in the centrifugal blower, in which FIG. 4A shows the intake air flow when the bottom surface of the scroll chamber 30 does not expand downward, and FIG. It is explanatory drawing which shows an intake air flow when the chamber bottom face part of the scroll chamber 30 is expanded below.

In the case of FIG. 4A, the upward flow is strong, and the reverse flow flows between the blades. On the other hand, in the case of FIG. 4B, the downward flow becomes strong, the upward flow becomes weak, and the reverse flow does not flow between the blades. This eliminates the collision with the intake air flow, and thus reduces noise.
And it turned out that the flow between blades can be improved by further changing the casing shape, in particular, the shape of the bottom surface portion of the scroll chamber 30 with respect to the prior art. Hereinafter, the chamber bottom portion of the scroll chamber 30 formed in a spiral shape on the outer peripheral side of the multiblade fan will be described with reference to FIG. In the scroll chamber 30, the chamber bottom surfaces 14 and 11 of the scroll chamber 30 gradually expand downward in the axial direction along with the expansion of the spiral, and the flow path area gradually increases from the winding start portion 1 a toward the discharge port 20.

In one embodiment of the present invention, the chamber bottom surface portions 14 and 11 have a steeply inclined chamber bottom surface portion 14 from the winding start portion 1a to the inclined cross sectional shape change portion 2a, and an inclined cross sectional shape, with the inclined cross sectional shape changing portion 2a as a boundary. It comprises a gently inclined chamber bottom surface portion 11 from the changing portion 2 a to the discharge port 20.
Then, the initial inclination angle θ _{0 at} the winding start portion 1a of the bottom surface portions 14 and 11 (expressed as an illustrative example, the inner cylindrical wall surface (40 in FIG. 2) in the vicinity of the bottom surface portion 14 inside the scroll chamber 30). , The angle formed with the vertical plane with respect to the rotation axis O when projected and deployed on the bottom surface of the chamber (see θ _{0 in} FIG. 2) is an angle range within 5.2 ° to 27.5 °, preferably The angle range is from 6.9 ° to 27.5 °. As a result, it was found that fan efficiency and noise were improved.
FIG. 5A is a graph showing the relationship between the initial inclination angle θ ₀ and fan efficiency in one embodiment of the present invention, and FIG. 5B is a graph showing the relationship between the initial inclination angle θ ₀ and noise. It is. Thus, a clear effect is produced when the initial inclination angle θ ₀ is in the angle range of 5.2 ° to 27.5 °.

  In another embodiment of the present invention, when the circumferential angle of the inclined cross-sectional shape changing portion 2a from the winding start portion is φ (measured around the rotation axis O), the circumferential angle φ of the inclined cross-sectional shape changing portion 2a is The inclined cross-sectional shape changing portion 2a is within an angular range within 30 to 60 ° in the circumferential direction from the winding start portion 1a, and the multi-blade fan is positioned downward in the axial direction from the position on the bottom surface portion of the winding start portion 1a. You may make it exist in the range position (H2) within 0.2-0.5H with respect to the impeller total height H. FIG. 6A is a graph showing the relationship between the circumferential angle φ of the inclined cross-sectional shape changing portion 2a and the fan efficiency in another embodiment of the present invention, and FIG. 6B is an inclined cross-sectional shape changing portion 2a. It is a graph which shows the relationship between the circumferential direction angle (phi) of this, and noise. Thus, a clear effect occurs when the circumferential angle φ of the inclined cross-sectional shape changing portion 2a is within an angle range of 30 to 60 °.

A mechanism for suppressing noise generation in the above embodiment will be described. FIG. 7A shows a state of air flow in the vicinity of the tongue when the steeply inclined chamber bottom surface portion 14 is extremely steeply inclined like a step, and FIG. 7B shows the steeply inclined chamber bottom surface portion 14 according to the present invention. It is explanatory drawing explaining the state of the airflow of the tongue part vicinity in the case of. When the steeply inclined chamber bottom surface portion 14 as shown in FIG. 7A is extremely steep, such as a step, a large number of vortices are generated, which causes a decrease in fan efficiency and noise. On the other hand, as shown in FIG. 7A, when the initial inclination angle θ ₀ is in an angle range of 5.2 ° to 27.5 °, the streamline changes smoothly and flows. Disturbance does not occur. In FIG. 2, W <b> 2 indicates the radial width of the bottom surface portions 14 and 11 of the scroll chamber 30, and W <b> 1 indicates the outlet tip T of the blade 2 (the outermost periphery of the multiblade fan 16) and the top surface of the scroll chamber 30. The distance from the outermost inner surface of 10 is said. If W2 is larger than W1 in all φ, the flow is not disturbed and is effective. W2 is preferably about 10 to 30% smaller than W1.

FIG. 8 is an example displaying the relationship between φ and H2 in one embodiment of the present invention. Reference numeral 101 is a comparative example in which the bottom surface of the chamber changes at a constant inclination without the inclined cross-sectional shape changing portion 2a. FIG. 9A is a graph showing the relationship between the flow coefficient and the fan efficiency by comparing the embodiment of the present invention of FIG. 8 with a comparative example, and FIG. 9B is a graph of the present invention of FIG. It is the graph which showed the relationship between a flow coefficient and a specific noise, comparing embodiment with a comparative example. The definition and test method of specific noise, flow coefficient, etc. conform to JIS.
In an example of the embodiment of the present invention, the inclined section shape changing portion 2a is at φ = 45 °. The embodiment of FIG. 8 is a typical case side shape of the present embodiment. The shape of the bottom surface of the chamber is changed from the beginning of winding 1a over the inclined cross-sectional shape changing portion 2a to form the steeply inclined bottom surface portion 14, and the flow passage cross-sectional area of the case is rapidly expanding. The winding start 1a is φ = 0 °, and the inclined sectional shape changing portion 2a is φ = 45 °. From the inclined cross-sectional shape changing portion 2a to the discharge outlet 20 at the end of winding, a gently inclined chamber bottom surface portion 11 having a shape that gently spreads downward is provided. As shown in FIG. 9, the effect in the use region is recognized as compared with the case of the bottom surface portion of the comparative example of FIG. 8.

  The wind flow discharged from the multiblade fan 16 collides with the tongue and suddenly changes the direction of the flow. However, the flow is induced toward the bottom by the effect of the steeply inclined chamber bottom 14 and causes the noise. It prevents entry into the space. As a result of the study by the present applicant, it is known that when the flow between the blades is quantitatively measured, noise is generated due to the influence of the back flow between the blades in a specific range (0 to 45 °). It is known that the flow in the case has the largest peripheral speed component accompanying the rotation of the multiblade fan. In order to prevent a back flow between the blades that are the source of the noise source with respect to the peripheral speed component, a particularly effective effect can be obtained when the position of the inclined cross-sectional shape changing portion 2a is in the range of 30 to 60 °. Was confirmed by experiments. When φ = 0 to 30 °, the flow is suddenly changed to the bottom of the chamber, so the performance is not improved. On the other hand, if φ = 60 ° or more, the backflow cannot be guided well to the bottom of the case, and no effect is produced.

10 (a) and 10 (b) are explanatory views showing another embodiment of the present invention.
In another embodiment of the present invention shown in FIG. 10A, the steeply inclined chamber bottom surface portion 14 from the winding start portion 1a to the inclined cross-sectional shape changing portion 2a is configured with a plurality of linear cross-sectional shapes. Although there are two stages here, a plurality of stages may be used. In another embodiment of the present invention shown in FIG. 10B, the steeply inclined chamber bottom surface portion 14 from the winding start portion 1a to the inclined cross-sectional shape changing portion 2a is configured with a curved cross-sectional shape. Here, it is an example constituted by a straight line and an arc. In either case of FIGS. 10A and 10B, the requirements of the invention of claim 1 are satisfied. In addition, the gently inclined chamber bottom surface portion 11 from the inclined sectional shape changing portion 2a to the discharge port 20 may be similarly configured with a plurality of linear sectional shapes.

2 Blades 11 Slowly inclined chamber bottom surface 13 Suction port 14 Steeply inclined chamber bottom surface 16 Multiblade fan 20 Discharge port 30 Scroll chamber 31 Casing

Claims (4)

A multiblade fan (16) in which a large number of blades (2) are arranged at regular intervals in the circumferential direction to form an impeller, and an air suction port (13) is provided above the impeller in the axial direction. When the fan exit angle (A) of the multiblade fan (16) is in an angle range of 20 ° to 75 ° and the outer diameter of the multiblade fan (16) is D. , A multiblade fan (16) having an impeller width (d) within a range of 0.05 to 0.15D, and a spiral around the multiblade fan (16) with a winding start portion (1a) as a starting point A scroll chamber (30) surrounded by a spiral casing (31) having an expansion angle within a range of 2 ° to 6 °, and the bottom surface portion of the scroll chamber (30) along with the expansion of the spiral ( 14, 11) gradually expands downward in the axial direction and discharges from the winding start portion (1a). In a centrifugal blower comprising a mouth (20) facing gradually spiral scroll chamber that the flow area is expanded (30), a
In the winding start portion of the chamber bottom part (14,11) (1a), the initial inclination angle theta ₀ toward the axially downwardly, Ri angular range der within 5.2 ° to 27.5 °,
The chamber bottom surface portion (14, 11) is a steeply inclined chamber bottom surface portion (14) from the winding start portion (1a) to the inclined cross sectional shape change portion (2a) with the inclined cross sectional shape change portion (2a) as a boundary. And a gently inclined chamber bottom surface portion (11) from the inclined sectional shape changing portion (2a) to the discharge port (20),
The angle (φ) that the inclined cross-sectional shape changing portion (2a) forms in the circumferential direction from the winding start portion (1a) with respect to the axis of the impeller is an angle range within 30 to 60 °, And in the range position (H2) within 0.2-0.5H with respect to the impeller total height H of the said multiblade fan from the position of the chamber bottom face in the said winding start part (1a) below in the said axial direction. A centrifugal blower characterized by that. The centrifugal blower according to claim 1 , wherein the steeply inclined chamber bottom surface portion (14) is constituted by a plurality of linear cross-sectional shapes. The centrifugal blower according to claim 1 , wherein the steeply inclined chamber bottom surface portion (14) has a curved cross-sectional shape. From the winding start portion (1a) to the discharge port (20), at an arbitrary angle (φ) formed in the circumferential direction from the winding start portion (1a) with respect to the shaft of the impeller,
The centrifugal blower according to any one of claims 1 to 3 , wherein a width W1 of an upper surface of the scroll chamber (30) is smaller than a width W2 of the chamber bottom surface portion (14, 11).

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