Blower

Abstract

To provide a blower capable of preventing a reduction in the fan performance by preventing the rotation of an impeller from being impaired by the existence of foreign matters.SOLUTION: A blower (100) includes a casing (110) having an intake port (114) on one end side in an axial direction and an exhaust port (140x) on another end side in the axial direction, an impeller (130) arranged inside the casing (110) and having a plurality of blades (133), and a plurality of ribs (140) provided on an inner peripheral face (113n) of the casing (110) while extending from the intake port side to the exhaust port side, and opposed to the blades (133). The number of the blades (133) is smaller than the number of the ribs (140), and the number of the ribs (140) is non-integral times the number of the blades (133).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a blower used for a cooling fan or the like.

Background Art

[0002] Conventionally, in an axial flow blower (hereinafter simply referred to as a "blower"), it includes a casing having an intake port on one end side in the axial direction and an exhaust port on the other end side, and an impeller disposed inside the casing.

[0003] In this type of blower, the impeller has a plurality of blades on the outer peripheral portion of the hub, and by rotating these plurality of blades together with the hub, air can be sucked from the intake port of the casing and discharged from the exhaust port.

[0004] Also, in this type of blower, it is known that the closer the gap between the inner peripheral surface of the casing and the blades of the impeller is, the better the static pressure-air volume performance. Generally, the radial gap (hereinafter referred to as the "radial gap") between the inner peripheral surface of the casing and the blades is designed to be 1 mm or less.

[0005] Also, in a cooling fan, a cooling air guide groove is formed on the inner peripheral surface of the impeller housing chamber of the fan casing, and the presence of the cooling air guide groove reduces the ventilation resistance to the blowing side of the cooling air and guides it, increasing the ventilation volume of the cooling air without generating a vortex and improving the cooling performance (see, for example, Patent Document 1).

[0006] Also, in an axial flow blower, a plurality of protrusions are provided on the inner peripheral surface of the casing, and by rectifying the airflow flowing along the inner peripheral surface of the casing so as to be directed toward the exhaust port side, air with high straightness is discharged from the exhaust port, and diffusion of the entire discharged air is suppressed (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0007] Patent Document 1 Japanese Patent Application Laid-Open No. 2000-130399 Patent Document 2 Japanese Patent No. 6183852 Summary of the Invention Problems to be Solved by the Invention

[0008] However, although the cooling fan of Patent Document 1 and the axial flow fan of Patent Document 2 do not particularly specify the radial clearance between the inner peripheral surface of the casing and the blades, it is generally assumed to be 1 mm or less. In this case, soil, sand, oil, or sludge may enter the clearance, or water droplets existing in the clearance may freeze in a low-temperature environment such as below the freezing point. The presence of these foreign substances may suppress the rotation of the impeller.

[0009] In view of the above points, an example of the problem of the present invention is to realize a blower that can prevent the rotation of the impeller from being impaired by the presence of foreign substances and prevent a decrease in fan performance. Means for Solving the Problems

[0010] The blower of the present invention includes a casing having an air inlet on one end side in the axial direction and an air outlet on the other end side in the axial direction, an impeller disposed inside the casing and having a plurality of blades, and a plurality of ribs provided so as to extend from the air inlet side to the air outlet side with respect to the inner peripheral surface of the casing and facing the blades. The number of blades is less than the number of ribs, and the number of ribs is a non-integer multiple of the number of blades. Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0012] <Embodiment> Hereinafter, an example of the present invention, this embodiment, will be described with reference to the drawings. FIG. 1 is a perspective view showing the overall configuration of a blower according to this embodiment which is an example of the present invention. FIG. 2 is a plan view showing the configuration when viewed from the intake port side of the blower according to this embodiment which is an example of the present invention. FIG. 3 is a plan view showing the configuration when viewed from the exhaust port side of the blower according to this embodiment which is an example of the present invention. FIG. 4 is a plan view showing the number of ribs facing the blades of the impeller in the blower according to this embodiment which is an example of the present invention, when viewed from the intake port side.

[0013] FIG. 5 is a table showing the relationships (A) and (B) between the number of ribs and the number of blades of the impeller in the blower according to this embodiment which is an example of the present invention. FIG. 6 is a plan view (A) and a partial enlarged perspective view (B) for explaining the separation portion between the ribs in the blower according to this embodiment which is an example of the present invention. FIG. 7 is a perspective view (A) showing the maximum thickness w2 of the blade and a perspective view (B) showing the width w1 of the tip of the rib in the blower according to this embodiment which is an example of the present invention.

[0014] FIG. 8 is a perspective view (A) and (B) showing the relationship between adjacent ribs in the blower according to this embodiment which is an example of the present invention. FIG. 9 is a perspective view showing the positional relationship between the intake port and the end portion on the intake port side of the rib in the blower according to this embodiment which is an example of the present invention. FIG. 10 is a perspective view showing the angle between the intake port and the end portion on the intake port side of the rib in the blower according to this embodiment which is an example of the present invention.

[0015] In the description of this embodiment, for the sake of convenience of explanation, the direction of arrow a along the axis X is taken as one end side or the intake port side, and the direction of arrow b along the axis X is taken as the other end side or the exhaust port side. Here, the direction of arrow ab is referred to as the axis X direction. Also, the direction of arrow cd is referred to as the radial direction, the direction of arrow c away from the axis X is referred to as the outer side or one side of the radial direction, and the direction of arrow d approaching the axis X is referred to as the inner side or the other side of the radial direction.

[0016] <Overview of the Blower in the Present Invention> In the blower according to the embodiment of the present invention, the closer the gap between the inner peripheral surface of the casing and the blades of the impeller is, the better the static pressure-air volume performance. Therefore, an attempt is made to make the gap between the inner peripheral surface of the casing and the blades of the impeller as narrow as possible. However, in this case, there is a risk that foreign matter may get into the gap between the inner peripheral surface of the casing and the blades, making it impossible to rotate.

[0017] Therefore, in the blower of the present invention, an attempt is made to reduce the narrow area where foreign matter may get in as much as possible while maintaining the static pressure-air volume performance. For this purpose, the blower of the present invention is provided with a plurality of ribs that narrow the gap between the inner peripheral surface of the casing and the blades of the impeller with respect to the inner peripheral surface of the casing, and a separation portion where the ribs do not exist is provided between the ribs adjacent to each other in order to suppress the intrusion of foreign matter.

[0018] <Blower> As shown in FIGS. 1 to 4, the blower 100 according to the present embodiment is a fan motor that sends air from the intake port side (arrow a direction) to the exhaust port side (arrow b direction) along the axis X (arrow ab direction), and has an overall cylindrical shape that is substantially square in plan view. The blower 100 has a casing 110 and an impeller 130 disposed inside the casing 110.

[0019] <Impeller> The impeller 130 has a cylindrical hub 131 disposed at the center and a plurality of (in this case, for example, seven) blades 133 protruding radially outward (arrow c direction) from the outer peripheral surface of the hub 131.

[0020] Incidentally, in the impeller 130, the hub 131 and the blades 133 are integrally formed by injection molding of a synthetic resin such as polybutylene terephthalate reinforced with, for example, glass fiber. Note that the impeller 130 may be formed of other materials such as metal materials.

[0021] At the center of the hub 131, on the exhaust port side (in the direction of arrow b), a shaft fixed to the hub 131 is rotatably supported by a motor (not shown) provided in the inner space of the hub 131. Examples of bearings that rotatably support the shaft in the motor include, but are not limited to, rolling bearings, sliding bearings, and hydrodynamic bearings.

[0022] An outer rotor type motor composed of a stator and a rotor is provided in the inner space of the hub 131. The motor is composed of, for example, a brushless DC motor or the like. In the blower 100, by sequentially supplying current to the coils of the stator from a power supply unit (not shown) at a predetermined timing, the rotor, the hub 131 fixed integrally with the rotor, and the blades 133 are rotated.

[0023] The plurality of blades 133 are integrally fixed to the outer peripheral surface of the hub 131 in a state of being gradually inclined from the end on the intake port side (in the direction of arrow a) to the end on the exhaust port side (in the direction of arrow b). Further, the blades 133 are inclined so as to gradually approach the intake port side (in the direction of arrow a) as they go in the rotation direction of the impeller 130 (counterclockwise direction when viewed from the intake port side (in the direction of arrow a)). Here, the plurality of blades 133 are provided on the outer peripheral surface of the hub 131 in a total of seven pieces at regular intervals, but the number is not limited to this, and any other arbitrary number may be used.

[0024] The blade 133 has a substantially trapezoidal shape in plan view, and is arranged such that the outermost peripheral edge 133s and the inner peripheral surface 113n in the impeller housing portion 113 are close to each other. The peripheral edge 133s of the blade 133 is arc-shaped and follows the arc-shaped curved surface of the inner peripheral surface 113n in the impeller housing portion 113. Therefore, the distance between the peripheral edge 133s of the blade 133 and the inner peripheral surface 113n in the impeller housing portion 113 is uniform. In practice, the gap between the inner peripheral surface 113n of the impeller housing portion 113 and the peripheral edge 133s of the blade 133 is set to, for example, 1 mm or less.

[0025] <Casing> The casing 110 of the blower 100 has a casing main body portion 111 having a rectangular tube shape in a plan view and a cylindrical impeller housing portion 113 provided at the center of the casing main body portion 111.

[0026] Note that the casing main body portion 111 and the impeller housing portion 113 of the casing 110 are integrally formed by injection molding of a synthetic resin such as polybutylene terephthalate reinforced with, for example, glass fiber. However, it is not limited to this, and the casing 110 may be formed of other metal materials or the like.

[0027] The casing main body portion 111 of the casing 110 is provided with through holes 111h through which bolts (not shown) for attaching to a predetermined device or housing are inserted at its four corners. The impeller housing portion 113 of the casing 110 is a cylindrical body having an inner diameter large enough to accommodate the impeller 130 inside.

[0028] As shown in FIG. 3, the casing main body portion 111 has four spokes 115 for supporting the impeller 130 on the exhaust port side (in the direction of arrow b) and a circular support plate 116 on which the impeller 130 is placed. In the casing main body portion 111, the four spokes 115 and the support plate 116 are integrally formed.

[0029] In this case, since the number of spokes 115 of the casing main body portion 111 is an even number of four, the number of blades 133 of the impeller 130 is set to an odd number of seven. This is because resonance occurs at a specific frequency and noise is generated when the number of spokes 115 is the same as the number of blades 133 or the number of blades 133 is an integer multiple of the number of spokes 115. In order to avoid this in advance, the number of spokes 115 and the number of blades 133 are made not to be the same number or an integer multiple.

[0030] As shown in Fig. 2, the impeller housing portion 113 has an air inlet 114 formed by an inclined surface for introducing air from an opening end surface 113e, which is an annular flat end surface on the air inlet side (in the direction of arrow a), into the inner space of the impeller housing portion 113.

[0031] This air inlet 114 has an annular shape connected to the opening end surface 113e, and is an inclined surface that slopes so as to gradually reduce in diameter from the opening end surface 113e of the impeller housing portion 113 toward the inner peripheral surface 113n of the impeller housing portion 113. That is, the air inlet 114 is a frustum of a cone.

[0032] The impeller housing portion 113 has an exhaust port at the end on the exhaust port side (in the direction of arrow b). However, the exhaust port is merely a circular end surface 140x (Fig. 10) on the exhaust port side (in the direction of arrow b) of the inner peripheral surface 113n of the impeller housing portion 113, and is not a particularly inclined surface like the air inlet 114.

[0033] <Rib> As shown in Figs. 1 and 4, a plurality of ribs 140 are provided on the inner peripheral surface 113n of the impeller housing portion 113 so as to extend from the air inlet side (in the direction of arrow a) to the exhaust port side (in the direction of arrow b).

[0034] The plurality of ribs 140 are arranged at regular intervals in the circumferential direction with respect to the inner peripheral surface 113n of the impeller housing portion 113, and face the circumferential edge 133s on the outer peripheral side of the blades 133 in the impeller 130.

[0035] Also, the ribs 140 are inclined so as to fall in the direction opposite to the rotation direction of the impeller 130 (the counterclockwise direction indicated by the white arrow). In other words, the ribs 140 are inclined from the air inlet side (in the direction of arrow a) to the exhaust port side (in the direction of arrow b) as they go in the rotation direction of the impeller 130. The ribs 140 are arranged on the inner peripheral surface 113n of the impeller housing portion 113 in a state where adjacent ribs 140 are parallel to each other.

[0036] <Relationship between rib and blade> In this case, the blower 100 has seven blades 133 of the impeller 130 and has 16 ribs 140 in the impeller housing portion 113 of the casing 110. Thus, in the blower 100, for example, the number of blades 133 is made less than the number of ribs 140 and is an integer equal to or greater than one-third of the number of ribs 140.

[0037] As a result, in the blower 100 (FIG. 4), there are 12 ribs 140 (surrounded by broken-line circles) at positions facing the peripheral edge 133s of the blade 133 and 4 ribs 140 at positions not facing the peripheral edge 133s of the blade 133. However, in the blower 100, depending on the stop position of the impeller 130, the number of ribs 140 facing the peripheral edge 133s of the blade 133 may vary by about one.

[0038] In the blower 100 in this case, compared to the case where the radial gap with the peripheral edge 133s of the blade 133 is close within 1 mm over the entire circumference of the inner peripheral surface 113n of the impeller housing portion 113, the number of ribs 140 facing the peripheral edge 133s of the blade 133 with a radial gap of 1 mm or less can be up to 13. In that case, at least one rib 140 does not face the blade 133 in the radial direction. Thus, in the blower 100, the risk of foreign matter intervening between the rib 140 and the peripheral edge 133s of the blade 133 can be reduced compared to the prior art.

[0039] Furthermore, in the blower 100, since a plurality of ribs 140 are arranged at regular intervals in the circumferential direction on the inner peripheral surface 113n of the impeller housing portion 113, in this case, there are five blades 133 arranged to face two ribs 140 and two blades 133 arranged to face only one rib 140. That is, the number of ribs 140 facing one blade 133 in the radial direction is two or less, and at least one blade 133 has one rib 140 facing it in the radial direction.

[0040] That is, in the blower 100, since two ribs 140 do not face all the blades 133, the risk of foreign matter getting caught between the rib 140 and the peripheral edge 133s of the blade 133 can be further reduced.

[0041] Incidentally, it is not necessary to limit the number of blades 133 of the impeller 130 to 7 and the number of ribs 140 to 16, and the number of blades 133 is an integer of 1 / 3 or more of the number of ribs 140. For example, the number of blades 133 can be 12 and the number of ribs 140 can be 20, or the number of blades 133 can be 7 and the number of ribs 140 can be 12. Alternatively, the number of blades 133 may be an integer of 1 / 2 or more of the number of ribs 140.

[0042] Note that the relationship between the number of blades 133 and the number of ribs 140 is not limited to this, and it is sufficient that the number of blades 133 is less than the number of ribs 140. That is, if the number of locations where the rib 140 and the peripheral edge 133s of the blade 133 are arranged to face each other can be reduced, the risk of foreign matter getting caught in the gap between the inner peripheral surface 113n of the impeller housing portion 113 and the blade 133 can be reduced compared to the conventional case. Therefore, the number of blades 133 may be 1 / 3 or more or less than the number of ribs 140, or 1 / 2 or more or less than the number of ribs 140.

[0043] In this way, in the blower 100, by setting the number of ribs 140 and the number of blades 133 so that there are portions of the plurality of ribs 140 that do not face the peripheral edge 133s of the blade 133, the risk of foreign matter getting caught between the rib 140 and the peripheral edge 133s of the blade 133 can be reduced.

[0044] Thus, in the blower 100, since there are a plurality of ribs 140 with a small gap from the peripheral edge 133s of the blade 133, it is possible to prevent the rotation of the impeller 130 from being suppressed while maintaining the static pressure - air volume performance without degrading it compared to the conventional case.

[0045] In addition, in the blower 100, when the number of ribs 140 is even, it is preferable that the number of blades 133 is odd, and when the number of ribs 140 is odd, the number of blades 133 is even.

[0046] This is because when the number of ribs 140 is the same as the number of blades 133, or when the number of ribs 140 is an integer multiple of the number of blades 133, resonance occurs at a specific frequency, generating a large amount of noise.

[0047] However, for the combinations of even and odd, or odd and even, it is not absolute. If noise due to resonance does not occur by arranging the ribs 140 unevenly with respect to the inner peripheral surface 113n of the impeller housing portion 113, combinations of even and even, or odd and odd may also be used.

[0048] For example, for the combination of even and odd, as shown in FIG. 5(A), when the number of ribs 140 is even (for example, 20, 16, 12), combinations where the number of blades 133 is odd (12 (exception), 9, 7, 5) can be considered.

[0049] Here, when there are 20 ribs 140 and 12 blades 133, although the number of ribs 140 is even, the number of blades 133 is also even. This is because when there are 20 ribs 140, instead of having 11 blades 133 which is more than half of 20, one additional blade 133 is added to the already formed 11 blades 133 to make 12 blades 133, and the arrangement of the blades 133 is made uneven.

[0050] In this way, by adding one blade 133 to the 11 blades 133 evenly arranged on the outer peripheral surface of the impeller 130 and making the arrangement of the 12 blades 133 overall uneven, the blower 100 can achieve an imbalance in the arrangement of the ribs 140 and the blades 133, preventing the generation of noise due to resonance.

[0051] That is, the blower 100 can prevent noise from occurring at a specific frequency by making the number of blades 133 less than the number of ribs 140, not making the number of ribs 140 and the number of blades 133 the same, and ensuring that the number of ribs 140 is not an integer multiple of the number of blades 133.

[0052] For reference, as shown in Fig. 5(A), when the number of ribs 140 is 20 and the number of blades 133 is 9, the number of ribs 140 is even while the number of blades 133 is odd. In this case, the number of blades 133 is less than or equal to half of the number of ribs 140.

[0053] Furthermore, as shown in Fig. 5(A), when the number of ribs 140 is 16 and the number of blades 133 is 7 or 5, the number of ribs 140 is even while the number of blades 133 is odd. In this case, when the number of blades 133 is 7, it is more than or equal to half of the number of ribs 140, and when the number of blades 133 is 5, it is more than or equal to one-third of the number of ribs 140. Similarly, the same pattern applies when the number of ribs 140 is 12.

[0054] On the other hand, for the combination of odd and even numbers, as shown in Fig. 5(B), when the number of ribs 140 is odd (e.g., 21, 15, 9), combinations where the number of blades 133 is even (12, 8, 6) can be considered.

[0055] Here, when the number of ribs 140 is 21 and the number of blades 133 is 12 or 8, the number of ribs 140 is odd while the number of blades 133 is even. When the number of blades 133 is 12, it is more than or equal to half of the number of ribs 140, and when the number of blades 133 is 8, it is less than half of the number of ribs 140.

[0056] Similarly, when there are 15 ribs 140 and the number of blades 133 is 12 or 8, the number of ribs 140 is odd while the number of blades 133 is even. Also, the number of blades 133 being 12 is more than half of the number of ribs 140, and the number of blades 133 being 8 is more than half of the number of ribs 140. Similarly, the following is the same pattern when the number of ribs 140 is 9.

[0057] In the blower 100, not only the relationship between the number of ribs 140 and the number of blades 133 is considered, but also the relationship and arrangement between the number of spokes 115 and the number of ribs 140 are taken into account. Specifically, in the casing main body 111 (Fig. 3), generally, the number of spokes 115 is generally formed of 3 or 4, and the number of ribs 140 is an integer multiple of the number of spokes 115.

[0058] This is because it is easier to evenly arrange the ribs 140 of the impeller accommodating portion 113 between the spokes 115 of the casing main body 111 by injection molding of the mold, and it is easier to form so that the spokes 115 and the ribs 140 do not spatially overlap along the axial direction X.

[0059] Therefore, in the blower 100, if the number of ribs 140 is an integer multiple of the number of spokes 115, for example, 4 spokes 115 and, for example, 16 ribs 140 can be arranged neatly.

[0060] Specifically, as shown in Fig. 3, in the casing main body 111, 4 spokes 115 are provided at equal intervals, and 4 ribs 140 are respectively provided along the circumferential direction between two adjacent spokes 115. By doing so, the blower 100 can be arranged in a well-balanced manner without the spokes 115 and the ribs 140 spatially overlapping in the axial direction X.

[0061] As shown in FIGS. 6(A) and 6(B), the rib 140 has a cross-sectional mountain shape that gradually rises from the inner peripheral surface 113n of the impeller housing portion 113 toward the axis X. The rib 140 includes a first concave portion 141 having a cross-sectional concave shape that gradually rises from the inner peripheral surface 113n of the impeller housing portion 113, a convex portion 142 having a cross-sectional convex shape joined to an end portion 141e of the first concave portion 141 and serving as a tip portion facing the circumferential edge 133s of the blade 133, and a second concave portion 143 having a cross-sectional concave shape joined to an end portion 142e of the convex portion 142 and gradually descending toward the inner peripheral surface 113n of the impeller housing portion 113.

[0062] The first concave portion 141 of the rib 140 is a curved surface that is arcuately concave in cross section. The convex portion 142 of the rib 140 is an arcuate curved surface that protrudes arcuately in cross section. The second concave portion 142 of the rib 140 is a curved surface that is arcuately concave in cross section, similar to the first concave portion 141.

[0063] Subsequently, as shown in FIGS. 7(A) and 7(B), the relationship between the maximum thickness w2 in the vicinity of the circumferential edge 133s of the blade 133 and the circumferential width w1 of the convex portion (tip portion) 142 of the rib 140 will be described.

[0064] The blade 133 is not uniform in thickness as a whole. As shown in FIG. 7(A), the blade 133 gradually becomes thinner from the central portion thereof toward the circumferential side edges 133e and 133f, and the central portion has the maximum thickness w2.

[0065] On one hand, the circumferential width w1 of the convex portion 142 in the rib 140 is the straight-line distance when the end 141e of the first concave portion 141 and the end 142e of the convex portion 142 are connected by a straight line along the circumferential direction. That is, the width w1 of the convex portion 142 which is the tip of the rib 140 is the straight-line distance connecting the end 141e which is the first boundary line between the first concave portion 141 and the convex portion 142, and the end 142e which is the second boundary line serving as the boundary between the convex portion 142 and the second concave portion 143. In the blower 100, the width w1 of this rib 140 is constant and does not change at any portion in the axial X direction. Note that the width w1 of the rib 140 may vary depending on the position in the axial X direction.

[0066] In the blower 100, the width w1 of the convex portion 142 of the rib 140 is smaller than the maximum thickness w2 of the blade 133. Thereby, in the blower 100, although the radial clearance between the convex portion 142 of the rib 140 and the circumferential edge 133s of the blade 133 is close to 1 mm or less, the range (area) where the rib 140 and the blade 133 face each other in the circumferential direction becomes small, and the risk of foreign matter intervening in the clearance between the two can be further reduced.

[0067] Also, as shown in FIG. 6, the portion between the convex portion 142 of one rib 140 and the convex portion 142 of the other rib 140 adjacent to each other in the circumferential direction is a portion including the inner peripheral surface 113n of the impeller housing portion 113. However, in order to distinguish this portion from the rib 140, the portion between the convex portion 142 of one rib 140 and the convex portion 142 of the other rib 140 shall be called the separation portion 145.

[0068] The plurality of separation portions 145 in the impeller housing portion 113 is the length D1 (FIG. 7(B)) connecting the end 141e in one rib 140 and the end 142e in the other rib 140 adjacent in the forward direction of the rotation direction of the impeller 130 along the circumferential direction. In other words, it can also be said to be the length between the convex portion 142 in one rib 140 and the convex portion 142 in the other rib 140.

[0069] The plurality of spaced portions 145 existing on the inner peripheral surface 113n of the impeller housing portion 113 exist alternately due to the presence of the plurality of ribs 140, and the circumferential length D1 thereof is longer than the width w1 of the convex portion 142 of the rib 140, that is, the circumferential length.

[0070] In this case, in the impeller housing portion 113, of the inner peripheral surface 113n, the area occupied by the spaced portions 145 between the plurality of ribs 140 is 70% or more of the whole. However, it is not limited to this, and by reducing the number of ribs 140 or reducing the width w1 of the convex portion 142 of the rib 140, the area occupied by the spaced portions 145 may be 80% or more, or 90% or more of the whole.

[0071] Incidentally, in the rib 140, the minimum radial clearance between the ridge portion 142s (FIGS. 6 and 7) that is the top of the convex portion 142 and the peripheral edge 133s of the blade 133 is 1 mm or less, and the radial interval between the peripheral edge 133s of the blade 133 and the inner peripheral surface 113n of the impeller housing portion 113 is preferably 3 mm or more.

[0072] The reason is that if the radial clearance between the peripheral edge 133s of the blade 133 is 1 mm or less, it is possible to prevent a decrease in the static pressure-air volume performance as in the conventional case. Further, if the radial interval between the peripheral edge 133s of the blade 133 and the inner peripheral surface 113n of the impeller housing portion 113 is 3 mm or more, it is possible to reduce the risk of foreign matter intervening in the gap and prevent the rotation of the impeller 130 from being suppressed.

[0073] By the way, as shown in FIG. 8(A), the two adjacent inclined ribs 140 are arranged on the inner peripheral surface 113n of the impeller housing portion 113 in a parallel state with each other, but preferably, the circumferential interval between the rib 140 and the rib 140 is further reduced.

[0074] The reason is that in the blower 100, if the interval between the rib 140 and the rib 140 is large, there is a risk that the air flowing from the intake port side to the exhaust port side by the blade 133 of the impeller 13 may flow backward.

[0075] Specifically, as shown in FIG. 8(B), it is preferable that the end portion 143g on the intake port side (in the direction of arrow a) of the second recess 143 in one rib 140 and the end portion 141g on the exhaust port side (in the direction of arrow b) of the first recess 141 in the other rib 140 spatially overlap in the axial X direction (in the direction of arrow ab). By doing so, in the blower 100, it is possible to suppress the backflow of air passing between two adjacent ribs 140 in the impeller housing portion 113.

[0076] However, when forming a plurality of ribs 140 in the impeller housing portion 113 of the casing 110 by injection molding, it is necessary to consider extracting the casing 110 as a molded product from the mold. Therefore, in that case, it is preferable that the second recess 143 in one rib 140 and the end portion 141g on the exhaust port side (in the direction of arrow b) of the first recess 141 in the other rib 140 do not spatially overlap in the axial X direction (in the direction of arrow ab).

[0077] Incidentally, as shown in FIG. 9, the plurality of ribs 140 protrude toward the blades 133 of the impeller 130 and are in a state of facing the peripheral edge 133s of the blades 133. However, the ribs 140 extend toward the front side in the rotation direction of the impeller 130 as they go from the intake port side (in the direction of arrow a) to the exhaust port side (in the direction of arrow b), while the peripheral edge 133s of the blades 133 obliquely extends toward the rear side in the rotation direction of the impeller 130 as it goes from the intake port side (in the direction of arrow a) to the exhaust port side (in the direction of arrow b). Therefore, the ribs 140 and the blades 133 face each other so as to cross each other.

[0078] Also, regarding the top portion on the intake port side (in the direction of arrow a) of the peripheral edge 133s of the blade 133 (the portion surrounded by the broken-line circle in FIG. 9), it faces the intake port 114 of the impeller housing portion 113 but does not face the rib 140.

[0079] That is, most of the peripheral edge 133s of the blade 133 will face the rib 140, but at the top (the portion surrounded by the dashed circle) of the peripheral edge 133s of the blade 133 on the air inlet side (in the direction of arrow a), it does not face the rib 140 and only faces the air inlet 114 of the impeller housing portion 113. As a result, in the blower 100, the air inflow is not hindered by that much, so that a decrease in the static pressure - air volume performance of the blower 100 can be suppressed. At the same time, in the blower 100, the area where foreign matter may be interposed between the rib 140 and the blade 133 can be reduced.

[0080] Furthermore, as shown in FIG. 10, the inclined end face 140t of the rib 140 on the air inlet side (in the direction of arrow a) is inclined from the air inlet side (in the direction of arrow a) toward the air outlet side (in the direction of arrow b) and is flush with the inclined air inlet 114 in the impeller housing portion 113.

[0081] Specifically, the air inlet 114 of the impeller housing portion 113 has an inclination angle of angle α from the opening end face 113e toward the end face 140t of the rib 140, and the end face 140t of the rib 140 also has an inclination angle of angle α from the air inlet side (in the direction of arrow a) toward the air outlet side (in the direction of arrow b).

[0082] As a result, in the blower 100, when air is sucked into the impeller housing portion 113 from the outside through the air inlet 114, the air does not strongly collide with the end face 140t of the rib 140, so that the air flow is not disturbed and the air can be efficiently discharged from the air outlet side (in the direction of arrow b).

[0083] Incidentally, for the end face 140x of the rib 140 on the air outlet side, since it serves as the air outlet and air is not sucked from there, it does not have to be inclined with respect to the horizontal direction orthogonal to the axis X direction (in the direction of arrows ab).

[0084] In the above configuration, the blower 100 is provided with a plurality of ribs 140 facing the blades 133 on the inner peripheral surface 113n of the impeller housing portion 113 of the casing 110, and the combination and arrangement of the number of ribs 140 and the number of blades 133 are determined so that not all of the plurality of ribs 140 are arranged to face the blades 133 of the impeller 130.

[0085] As a result, in the blower 100, the presence of the plurality of ribs 140 can suppress the decrease in the static pressure-air volume performance caused by the impeller 130, and since it is possible to avoid a state where all of the plurality of ribs 140 are arranged to face the peripheral edge 133s of the blade 133, the risk of foreign matter intervening in the gap between the rib 140 and the blade 133 can be significantly reduced compared to the prior art.

[0086] Further, in the blower 100, the area occupied by the separation portions 145 between the plurality of ribs 140 in the inner peripheral surface 113n of the impeller housing portion 113 is at least 70% or more of the whole, and by increasing the area not facing the ribs 140, the risk of foreign matter intervening in the gap between the rib 140 and the blade 133 can be significantly reduced compared to the prior art.

[0087] In particular, in the blower 100, in a low temperature environment such as below freezing (for example, about minus 20 degrees Celsius), although ice due to freezing may intervene as foreign matter between the rib 140 provided on the inner peripheral surface 113n of the impeller housing portion 113 and the peripheral edge 133s of the blade 133, since there are few locations where the rib 140 and the blade 133 face each other and the facing area is small, it is possible to rotate the impeller 130 by the motor, and malfunction can be prevented.

[0088] <Other Embodiments> The above has described the blower of the present invention with preferred embodiments, but the blower of the present invention is not limited to the configuration of the blower 100 disclosed in the above embodiments. In the above-described embodiment, the case where the rib 140 that bulges in a cross-sectional mountain shape is provided on the inner peripheral surface 113n of the impeller housing portion 113 has been described, but ribs having other cross-sectional shapes such as a rectangular cross-section, a trapezoidal cross-section, a triangular cross-section, and an arcuate cross-section may be provided.

[0089] Also, in the embodiment of the present invention, the case where the radial gap between the rib 140 and the peripheral edge 133s of the blade 133 is set to 1 mm or less and the radial interval between the inner peripheral surface 113n of the impeller housing portion 113 and the peripheral edge 133s of the blade 133 is set to 3 mm or more has been described.

[0090] However, the present invention is not limited to this. In the trade-off relationship between the static pressure - air volume performance and the risk of foreign matter intervening, when giving priority to the static pressure - air volume performance, the radial gap between the rib 140 and the peripheral edge 133s of the blade 133 is 1 mm or less, and the radial interval between the inner peripheral surface 113n of the impeller housing portion 113 and the peripheral edge 133s of the blade 133 is less than 3 mm. When giving priority to preventing the intervention of foreign matter, the radial gap between the rib 140 and the peripheral edge 133s of the blade 133 is 1 mm or more, and the radial interval between the inner peripheral surface 113n of the impeller housing portion 113 and the peripheral edge 133s of the blade 133 is 3 mm or more. Various combinations may be set.

[0091] In addition, those skilled in the art can appropriately modify the blower of the present invention and change the combinations of various configurations according to conventionally known knowledge. As long as the configuration of the present invention is still provided by such changes, of course, it is included in the scope of the present invention.

Explanation of Reference Numerals

[0092] 100…Blower, 110…Casing, 111…Casing main body, 111h…Through hole, 113…Impeller housing, 113e…Open end face, 113n…Inner peripheral surface, 114…Air inlet, 115…Spoke, 116…Support plate, 130…Impeller, 131…Hub, 133…Blades, 133e, 133f…Side edges, 133s…Peripheral edge, 140…Rib, 140t…End face, 140x…End face, 141…First recess, 141g…End, 142…Protrusion 142 (tip), 142s…Ridge, 143…Second recess, 143g…End, 145…Separation part, D1…Length, w1…Width, w2…Maximum thickness.

Claims

1. A casing having an air inlet on one end side in the axial direction and an air outlet on the other end side in the axial direction, An impeller disposed inside the casing and having a plurality of blades, A plurality of ribs provided so as to extend from the air inlet side to the air outlet side with respect to the inner peripheral surface of the casing and facing the blades, Comprising, The number of the blades is less than the number of the ribs, The number of the ribs is a non-integer multiple of the number of the blades A blower.

2. When the number of the ribs is even or odd, the number of the blades is odd or even The blower according to claim 1.

3. The number of the ribs facing one of the blades is 2 or less, The blower according to claim 1 or 2.

4. At least one of the blades has one rib facing it in the radial direction The blower according to claim 3.

5. The width of the tip of the rib facing the blade is smaller than the maximum thickness of the blade, The blower according to claim 1.

6. The rib has a cross-sectional mountain shape gradually rising from the inner peripheral surface of the casing, and has a first concave portion rising from the inner peripheral surface, a convex portion joined to an end of the first concave portion, and a second concave portion joined to the convex portion and falling toward the inner peripheral surface, The blower according to claim 1.

7. The width of the tip of the rib is the straight-line distance connecting a first boundary line that is the boundary between the first concave portion and the convex portion and a second boundary line that is the boundary between the convex portion and the second concave portion, and a separation portion is formed between the convex portions of the ribs adjacent to each other in the circumferential direction, and the length of the separation portion in the circumferential direction is longer than the width of the tip of the rib, The blower according to claim 6.

8. The rib extends in an inclined state from the air inlet side to the air outlet side, and the end of one rib adjacent to the other rib on the air inlet side is spatially overlapped with the other rib in the axial direction The blower according to claim 1.

9. The end of the rib on the air inlet side has an end face continuous with the inclined face forming the air inlet in the casing, the blower according to claim 1.

10. The casing has a plurality of spokes for rotatably supporting the impeller, When the number of the spokes is even or odd, the number of the ribs is also even or odd, The blower according to claim 1 or 7.

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