Blower and combustion device equipped with same

Abstract

To provide a blower device capable of properly reducing noise, and a combustion apparatus comprising the same.SOLUTION: There is provided a blower device A that comprises an impeller I which is housed in a casing 2 and made to rotate, wherein the impeller I has a plurality of blades 5 forming a plurality of inter-blade flow passages 61 and a center space part 60, and when the impeller I rotates, air flowing in the center space part 60 through an intake port 24 of the casing 2 flows outward in the plurality of inter-blade flow passages 61. Each of the blades 5 comprises, as noise reduction means for reducing noise generated when the air passes through the plurality of inter-blade flow passages 61; a plurality of first uneven parts 51 which are recessed on the side of a first surface 5a between the first and a second surfaces 5a, 5b corresponding to both top and reverse surfaces of the blade 5, and also projected on the side of the other second surface 5b; and a plurality of second uneven parts 52 which are recessed on the side of the second surface 5b and projected on the side of the first surface 5a to the contrary.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a blower such as a centrifugal blower, and a combustion apparatus equipped with the same. [Background technology]

[0002] The present applicant has previously proposed specific examples of blowers described in Patent Documents 1 to 3. The blower devices described in these documents have an impeller housed in a casing and rotatably driven by a motor. The casing has an air intake port and an air outlet port. The impeller has a plurality of blades arranged at intervals in the circumferential direction, and a region closer to the center than the plurality of blades forms a central space that communicates with inter-blade flow passages formed between the plurality of blades. When the impeller rotates, air flows from the outside of the casing into the central space of the impeller through the air intake port, passes through the inter-blade flow passages, and flows out around the periphery of the impeller before reaching the air outlet port and being discharged from the air outlet port to the outside of the casing.

[0003] However, the above-mentioned conventional technology has room for improvement as follows.

[0004] Quietness (low noise) is often a required performance feature of a blower. However, the blower with the above-described configuration uses centrifugal force generated when the multiple blades of the impeller rotate to forcibly flow air toward the outer periphery of the impeller in the inter-blade passages of the impeller, resulting in a relatively loud noise caused by this airflow. Therefore, it is desirable to improve this feature.

[0005] Patent Document 4 describes a means for reducing the noise described above by providing dimples on one side of each blade of an impeller. This method generates small-scale turbulence at the dimpled locations when air flows along the one side of each blade, suppressing the separation of the airflow from the one side, thereby reducing the blower noise caused by the separation of the airflow. However, it is difficult to achieve sufficient quietness with this effect alone, and further improvement in the noise reduction effect is desired. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-110526 A [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-150472 [Patent Document 3] Japanese Patent Application Publication No. 2020-133495 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-133254 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention was conceived in light of the above-mentioned circumstances, and its object is to provide a blower device that can appropriately reduce noise, and a combustion device equipped with the same. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following technical solutions.

[0009] A first aspect of the present invention provides a blower comprising: a casing having an intake port and an exhaust port; and an impeller housed in the casing and rotated; the impeller having a plurality of blades arranged at intervals in the circumferential direction to form a plurality of inter-blade passages, and a region closer to the center than the plurality of blades forming a central space communicating with the plurality of inter-blade passages; and when the impeller rotates, air that has flowed into the central space via the intake port passes through the plurality of inter-blade passages to a radially outward side of the impeller. The blower comprises: a first surface and a second surface corresponding to the front and back surfaces of each blade, each of which has a plurality of first concave-convex portions that are concave on the first surface side and convex on the other second surface side; and a second surface that is convex on the second surface side and concave on the first surface side, as means for reducing noise generated when air passes through the plurality of inter-blade passages. The plurality of first and second uneven portions are arranged in a plurality of rows in the radial direction and width direction of the impeller, which intersect with each other, and the rows of the plurality of first uneven portions and the rows of the plurality of second uneven portions are arranged in a staggered arrangement, with their positions shifted from each other in the radial direction and the width direction. It is characterized by the following.

[0010] This configuration provides the following effects. That is, each blade of the impeller is provided with a plurality of first and second uneven portions, each of which is concave on one side and convex on the other side of the front and rear surfaces (first and second surfaces) of each blade. The concave portion of one side creates a so-called dimple effect, suppressing airflow separation and suppressing Karman vortices. The convex portion of the other side can also create an effect similar to or similar to the dimple effect of the concave portion. Thus, the presence of the plurality of first and second uneven portions can reduce noise generated when the impeller rotates and air flows through the inter-blade flow passages. These first and second uneven portions are provided on both sides (first and second surfaces) of each impeller blade. This provides a superior noise reduction effect and improved quietness compared to, for example, Patent Document 4, in which the uneven portions are provided on only one surface. Furthermore, according to the present invention, the cross-sectional shapes of the first and second uneven portions provided on each blade can be symmetrical or nearly symmetrical to each other. This prevents warping and allows each blade to accurately maintain its shape. Unlike the present invention, if each blade were provided with only the first uneven portion, each blade would have only concave regions on the first surface and only convex regions on the second surface, making it prone to warping and other deformations. However, according to the present invention, such defects can be appropriately avoided. Furthermore, with this configuration, the multiple first and second uneven portions provided on each blade of the impeller are arranged in a manner that effectively acts on the airflow in the inter-blade flow passages, which is even more preferable in terms of enhancing the noise reduction effect.

[0011] In the present invention, preferably, each of the blades is made of a metal plate, and each of the first and second uneven portions is a pressed portion.

[0012] With this configuration, the first and second uneven portions of each blade can be formed relatively easily by press working. Because press working is performed on both surfaces (first and second surfaces) of each blade, warping deformation of each blade can be prevented.

[0013] In the present invention, preferably, each of the first and second uneven portions has a concave spherical surface on one side and a convex spherical surface on the other side, the concave spherical area has a circular shape in front view with a diameter of 1.0 to 3.0 mm, and the depth of the deepest part is 0.4 mm or more.

[0014] The present inventors have conducted repeated tests on the relationship between the shape and size of the first and second uneven portions and the noise reduction effect, and have found that the above configuration provides a superior noise reduction effect, which can be understood from the contents described below with reference to Table 1.

[0017] In the present invention, preferably, the total front-view projected area of ​​the plurality of first and second uneven portions in each blade is greater than the total area of ​​the non-uneven portions sandwiched between the plurality of first and second uneven portions.

[0018] According to this configuration, the first and second uneven portions are arranged at a high density so that the area of ​​the non-uneven portion sandwiched between the first and second uneven portions is small, thereby further enhancing the noise reduction effect achieved by utilizing the first and second uneven portions.

[0019] In the present invention, preferably, the total front-view projected area of ​​the plurality of first and second uneven portions and the non-uneven portions sandwiched between them in each blade exceeds half the area of ​​each of the first and second surfaces of each blade.

[0020] According to this configuration, the plurality of first and second uneven portions are provided over a wide range of each blade, so that a sufficient noise reduction effect can be expected.

[0021] In the present invention, preferably, the impeller further includes a plurality of auxiliary blades located radially outward of the impeller between the plurality of blades to divide the inter-blade flow passage into a plurality of regions in the circumferential direction, and the plurality of first and second uneven portions are also provided on each of the auxiliary blades.

[0022] This configuration provides the following effects. That is, when the blades of an impeller are arranged radially, for example, the inter-blade passages become wider as they move radially outward. Therefore, when air flows through the wider portions of the inter-blade passages, there may be a large amount of air that does not flow near both sides (first and second surfaces) of each blade and does not flow near the locations where the first and second uneven portions are formed, which can cause noise. In contrast, with the above-described configuration, the auxiliary blades are arranged in the locations of such airflows, and it is possible to further achieve a noise reduction effect by utilizing the first and second uneven portions provided on these auxiliary blades.

[0023] A combustion apparatus provided by a second aspect of the present invention is a combustion apparatus comprising a burner and a blower for supplying combustion gas to the burner, characterized in that the blower provided by the first aspect of the present invention is used as the blower.

[0024] According to this configuration, the same effects as those described for the blower provided by the first aspect of the present invention can be obtained.

[0025] Other features and advantages of the present invention will become more apparent from the following description of the preferred embodiments of the invention, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view showing an example of a blower according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the blower shown in FIG. [Figure 3] FIG. 2 is a perspective view of an impeller of the blower shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. [Figure 5] FIG. 5 is a front view of the blades of the impeller shown in FIGS. 3 and 4. [Figure 6] (a) is a cross-sectional view taken along line VIa-VIa in FIG. 5, (b) is a cross-sectional view taken along line VIb-VIb in FIG. 5, (c) is a cross-sectional view taken along line VIc-VIc in FIG. 5, and (d) is an enlarged cross-sectional view of a portion of (a). [Figure 7] 3 is a cross-sectional view of a main part showing an example of a combustion device configured with the air blower shown in FIGS. 1 and 2 and a hot water supply device configured using this combustion device. FIG. [Figure 8] FIG. 4 is a partially cutaway plan view showing another example of an impeller according to the present invention. [Figure 9] 9(a) is a front view of the auxiliary blade of the impeller shown in FIG. 8, (b) is a cross-sectional view taken along line IXb-IXb of (a), and (c) is a cross-sectional view taken along line IXc-IXc of (a). DETAILED DESCRIPTION OF THE INVENTION

[0027] Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0028] The air blower A shown in Figures 1 and 2 is a centrifugal type and includes an impeller I, a casing 2 that houses the impeller I, and a motor M for driving and rotating the impeller I. Each blade 5 of the impeller I is provided with a plurality of first and second uneven portions (stepped portions) 51, 52, which will be described later.

[0029] The casing 2 includes a front wall 21 having an air intake port 24 formed therein, a rear wall 22 facing the front wall 21 at a distance, and a peripheral wall 20. A motor mounting plate 23, to which a motor M is screwed, is attached to the rear wall 22 using screws 90. The motor mounting plate 23 closes an opening 22a provided in the rear wall 22 for inserting and removing the impeller I. The peripheral wall 20 surrounds the outer periphery of the impeller I and forms an air outlet 4a at its upper portion. An air flow path 4 is formed between the outer periphery of the impeller I and the peripheral wall 20, which guides air flowing out from an inter-blade flow path 61 of the impeller I (described later) to the air outlet 4a.

[0030] As clearly shown in FIGS. 2 to 4, the impeller I includes a front shroud 12, a rear shroud 13, and a plurality of blades 5. The blades 5 are arranged radially at intervals in the circumferential direction of the impeller I and extend in a substantially straight line in the radial direction of the impeller I, and the blower A of this embodiment is configured as a radial fan. Inter-blade flow paths 61 are formed between the blades 5, and a region closer to the center of the impeller I than the blades 5 forms a central space 60 that communicates with the inter-blade flow paths 61.

[0031] The front shroud 12 is a hollow disk with an intake opening formed in the center. The rear shroud 13 is a disk with approximately the same outer diameter as the front shroud 12. The blades 5 are sandwiched and fixed between the front shroud 12 and the rear shroud 13. As shown in FIG. 5 , for example, this fixing means employs a means for inserting a plurality of crimping protrusions 59 provided on the front and rear portions (top and bottom in FIG. 5 ) of each blade 5 into a plurality of holes 12a, 13a provided in the front shroud 12 and the rear shroud 13 for crimping.

[0032] The center of the rear shroud 13 is attached to the drive shaft 30 of the motor M using a nut member 31 or the like, which allows the impeller I to rotate freely using the motor M. When the impeller I rotates, air outside the casing 2 flows from the air intake 24 into the central space 60, then flows through the multiple inter-blade flow passages 61 to the radially outward side of the impeller I and out into the air flow passage 4, and then flows out of the casing 2 from the air outlet 4a.

[0033] As shown in FIGS. 5 and 6, each blade 5 has a plurality of inter-blade flow passages 61 through which air flows. A plurality of first and second uneven portions 51, 52 are provided as a means for reducing noise generated when the vehicle passes through the area (in FIG. 5, the first uneven portion 51 has a dotted pattern, and the second uneven portion 52 does not have a dotted pattern). Here, when both the front and back surfaces of the blade 5 are the first and second surfaces 5a, 5b, the first uneven portion 51 has a concave spherical surface with an appropriate radius of curvature Ra (see FIG. 6(d)) on the first surface 5a side, and a convex spherical surface corresponding to the concave spherical surface on the second surface 5b side. Preferably, the peripheral edge of the concave spherical surface is rounded with an appropriate radius of curvature Rb. More preferably, the radius of curvature Rb is smaller than the plate thickness t. By appropriately reducing the radius of curvature Rb, the shape of the concave spherical surface can be made sharper, thereby improving the dimple effect described below. On the other hand, the second uneven portion 52 is symmetrical to the first uneven portion 51, with the second surface 5b being a concave spherical surface and the first surface 5a being a convex spherical surface, unlike the first uneven portion 51.

[0034] Specific examples of the sizes of the first and second uneven portions 51, 52 will be described later, but these are sizes that can produce a dimple effect or an effect similar to this on the airflow. These are also pressed portions formed by applying press processing (step pressing) to each metallic blade 5 from both sides in the thickness direction.

[0035] 5, the first and second uneven portions 51, 52 are arranged in a staggered pattern. More specifically, the first and second uneven portions 51, 52 are arranged in multiple rows in the radial and width directions of the impeller I, and the multiple rows of the first uneven portions 51 and the multiple rows of the second uneven portions 52 are arranged alternately with a positional shift in both the radial and width directions.

[0036] Furthermore, the first and second uneven portions 51, 52 are densely arranged so that their total projected area a1 (not the area of ​​the three-dimensional components of the concave and convex spherical surfaces) when viewed from the front is larger than the total area a2 of the non-uneven portions (flat regions) between the first and second uneven portions 51, 52. Preferably, the total area (a1 + a2) of the projected area when viewed from the front of the first and second uneven portions 51, 52 and the non-uneven portions sandwiched between the first and second uneven portions 51, 52 exceeds half the area of ​​each of the first and second surfaces 5a, 5b of the blade 5.

[0037] The above-described blower A is used as a component of a combustion device C as shown in FIG. The combustion device C shown in the figure includes a burner 8 housed in a case 80 and a blower A attached to the case 80 so as to be able to supply combustion air to the burner 8. The hot water supply device WH includes a heat exchanger 9 that uses the combustion gas generated by the burner 8 to heat hot water.

[0038] Next, the operation of the above-mentioned blower A will be described.

[0039] First, as described above, when the impeller I is rotated by the motor M, external air flows into the central space 60 of the impeller I from the air intake 24, and then passes radially outward through each inter-blade flow path 61 to flow into the air flow path 4, and then flows out of the casing 2 from the air outlet 4a. In contrast, each blade 5 of the impeller I is provided with a plurality of first and second uneven portions 51, 52, one surface of which is a concave spherical surface and the other surface of which is a convex spherical surface. The concave spherical surface produces a dimple effect, as described below, which provides a noise reduction effect.

[0040] That is, when air flows along each blade 5, small-scale turbulence is generated at the locations where the concave spherical surfaces of the first and second uneven portions 51, 52 are formed, and the laminar boundary layer that flows along the first and second surfaces 5a, 5b, that is, the front and back surfaces of each blade 5, becomes more likely to become a turbulent boundary layer. As a result, the air flow along the first and second surfaces 5a, 5b of each blade 5 is less likely to separate from the first and second surfaces 5a, 5b, and the regular generation of Karman vortices is also less likely to occur. As a result, the noise of the air flow is reduced, and the quietness of the blower A can be improved. On the other hand, the same effect as described above can be obtained at the locations where the convex spherical surfaces of the first and second uneven portions 51, 52 are formed, making it possible to reduce noise caused by airflow.

[0041] In this embodiment, the first and second uneven portions 51, 52 that produce the noise reduction effect described above are provided on both the front and back surfaces (first and second surfaces 5a, 5b) of each blade 5, making it possible to achieve a significantly excellent noise reduction effect.

[0042] The inventors fabricated a prototype similar to the above-described blower device A and conducted an experiment to determine the relationship between the shape and size of the first and second uneven portions 51, 52 and the noise reduction effect. As a result, the experimental data shown in Table 1 below was obtained. [Table 1]

[0043] The data in Table 1 shows the sound pressure levels (A-weighted (auditory weighting)) when the first and second uneven portions 51, 52 are configured with a concave spherical surface on one side and a convex spherical surface on the other side, and the depth d of the deepest part of the concave spherical surface is changed in stages from 0.1 to 0.5. The arrangement of the first and second uneven portions 51, 52 is the same as the arrangement shown in Figure 5, and the other configurations of each part and the operating conditions of the blower A are the same. The plate thickness t of the blades 5 is 0.4 mm.

[0044] As shown in Table 1, when the depth d of the deepest part of the concave spherical surface is 0.4 mm or more, the noise reduction effect is clearly superior to when it is less than that. Furthermore, when such experiments were conducted by changing the diameter D of the concave spherical surface in a front view, experimental results showing a similar tendency to those in Table 1 were obtained in the range of diameter D of 1.0 to 3.0 mm, which is a circular shape in a front view. Furthermore, although not shown in Table 1, it was found that the thickness t of the plate does not have a significant effect on the noise reduction effect. Therefore, when the first and second uneven portions 51, 52 have a concave spherical surface on one side and a convex spherical surface on the other side, and the concave spherical area is within the range of a circular shape in front view with a diameter D of 1.0 to 3.0 mm, it is preferable that the depth d of the deepest part is 0.4 mm or more.

[0045] According to the blower A of this embodiment, the first and second uneven portions 51, 52 provided on each blade 5 are symmetrical to each other, which prevents warping and other deformations from occurring in each blade 5 and ensures that each blade 5 accurately maintains its shape. If each blade 5 were provided with, for example, only the first uneven portion 51, there would be a risk of warping and deformation in each blade 5, but according to this embodiment, it is possible to eliminate such a risk.

[0046] 8 and 9 show another embodiment of the present invention. In these figures, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as in the above embodiment, and redundant explanations will be omitted. Abbreviated.

[0047] The impeller Ia shown in Fig. 8 is equipped with a plurality of support blades 5A. The length of each support blade 5A in the radial direction of the impeller Ia is shorter than that of each blade 5, and each support blade 5A is located radially outward of the impeller Ia within the spaces between the plurality of blades 5 (inter-blade passages 61). As a result, the radially outward region of each inter-blade passage 61 is divided into two by each support blade 5A (note that, unlike this embodiment, it is also possible to provide each inter-blade passage 61 with a plurality of support blades 5A, thereby dividing each inter-blade passage 61 into three or more regions). Although not shown in Fig. 8, each support blade 5A is also provided with a plurality of first and second uneven portions 51, 52, as shown in Fig. 9. The total number of the plurality of first and second uneven portions 51, 52 provided on each support blade 5A differs, but they are basically arranged in a staggered pattern similar to that shown in Fig. 5.

[0048] The multiple blades 5 of the impeller Ia are arranged radially, and the inter-blade passages 61 are wider toward the radially outer sides of the impeller Ia. Therefore, when air flows through the wider portions of the inter-blade passages 61, much of the air does not flow near the first and second uneven portions 51, 52 provided on each blade 5, which can increase noise. In contrast, according to this embodiment, air flows near the first and second uneven portions 51, 52 provided on the support blade 5A in the wider portions, thereby achieving a noise reduction effect using the first and second uneven portions 51, 52.

[0049] The present invention is not limited to the above-described embodiment, and the specific configurations of the blower device and combustion device according to the present invention can be freely designed and modified in various ways within the intended scope of the present invention.

[0050] Although preferred specific examples of the shapes and sizes of the first and second uneven portions have been described with reference to Table 1, they are not limited to these specific examples, and the specific shapes, sizes, total numbers, arrangements, etc. can be changed in various ways. In essence, the first and second uneven portions in the present invention function as means for reducing noise generated when air passes through a plurality of inter-blade flow passages, and the first uneven portion may be concave on the first surface side of each blade of the impeller and convex on the second surface side. The second uneven portion may be the opposite of the first uneven portion, being concave on the second surface side and convex on the first surface side. The first and second uneven portions can be formed by pressing the metal blades, or they can be molded integrally with the resin blades. There is no specific method for forming the first and second uneven portions.

[0051] The blower device of the above-described embodiment is configured as a radial fan in which each of the multiple blades extends linearly in the radial direction, but alternatively, it can also be configured as, for example, a turbofan in which each of the multiple blades is curved.

[0052] The blower device according to the present invention can be used for purposes other than as a component of a combustion device. The combustion device according to the present invention is not limited to a water heater, and can be configured as a combustion device for heating, for example, and the purpose and use of combustion are not limited. [Explanation of symbols]

[0053] A. Blower C. Combustion device I Impeller Medium motor 2 Casing 24 Air intake 4 Air Flow Channel 4a Air outlet 5 Feathers 5A auxiliary blade 5a, 5b First and second surfaces (of the blade) 51, 52 First and second uneven portions 60 Central space 61 Blade passage

Claims

1. a casing having an air intake and an air outlet; an impeller that is accommodated in the casing and rotated; The impeller has a plurality of blades arranged at intervals in the circumferential direction to form a plurality of inter-blade flow passages, and a region closer to the center than the plurality of blades forms a central space portion that communicates with the plurality of inter-blade flow passages, a blower configured such that, when the impeller rotates, air flowing into the central space through the air intake passes through the plurality of inter-blade flow passages toward a radially outward side of the impeller, Each of the blades is provided with a plurality of first concave-convex portions that are concave on the first surface side and convex on the other second surface side of a first and second surface corresponding to the front and back surfaces of the blade, as means for reducing noise generated when air passes through the plurality of inter-blade flow passages, and convex-convex portions that are convex on the second surface side and concave on the first surface side, respectively; and a blower device characterized in that the plurality of first and second uneven portions are arranged in multiple rows in the radial and width directions of the impeller that intersect with each other, and the rows of the plurality of first uneven portions and the rows of the plurality of second uneven portions are arranged in a staggered pattern in which they are alternately aligned with a positional shift in the radial and width directions.

2. The blower device according to claim 1, The air blower, wherein each of the blades is made of a metal plate, and each of the first and second uneven portions is a pressed portion.

3. The blower device according to claim 1 or 2, each of the first and second concave and convex portions has a concave spherical surface on one side and a convex spherical surface on the other side; The concave spherical region has a circular shape in front view with a diameter of 1.0 to 3.0 mm and a depth at its deepest point of 0.4 mm or more.

4. The air blower according to any one of claims 1 to 3, A blower device, wherein the total front-view projected area of ​​the plurality of first and second uneven portions on each blade is greater than the total area of ​​the non-uneven portions sandwiched between the plurality of first and second uneven portions.

5. The air blower according to any one of claims 1 to 4, a blower device in which the total front-view projected area of ​​the plurality of first and second uneven portions and the non-uneven portions sandwiched between them on each blade exceeds half of the area of ​​each of the first and second surfaces of each blade.

6. The air blower according to any one of claims 1 to 5, the impeller further includes a plurality of auxiliary blades that are located radially outward of the impeller among the plurality of blades and divide the inter-blade flow passage into a plurality of regions in the circumferential direction, The plurality of first and second uneven portions are also provided on each of the support blades.

7. A combustion device comprising a burner and a blower for supplying combustion gas to the burner, A combustion device, characterized in that the blower device according to any one of claims 1 to 6 is used as the blower device.

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