Blower

Abstract

The present invention realizes a blower capable of preventing the rotation of an impeller from being impaired due to the existence of foreign matter and preventing deterioration of fan performance.　A blower (100) of the present invention comprises: 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) disposed inside the casing (110) and having a plurality of blades (133); and a plurality of ribs (140) provided on an inner peripheral surface (113n) of the casing (110) to extend from the intake port side to the exhaust port side, and facing the blades (133). The number of blades (133) is less than the number of ribs (140), and the number of ribs (140) is a non-integral multiple of the number of blades (133).

Description

blower

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

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

[0003] In this type of blower, the impeller has multiple blades on the outer periphery of a hub, and these multiple blades rotate together with the hub, allowing air to be drawn in through the intake port of the casing and expelled through the exhaust port.

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

[0005] Furthermore, in a cooling fan, a cooling air guide groove is formed on the inner peripheral surface of the impeller housing of the fan casing, and the existence of this cooling air guide groove guides the cooling air to the outlet side with reduced ventilation resistance, thereby increasing the amount of cooling air passing through without generating vortices and improving cooling performance (see, for example, Patent Document 1).

[0006] Furthermore, in an axial flow fan, a fan has been proposed in which multiple protrusions are provided on the inner peripheral surface of the casing to straighten the airflow flowing along the inner peripheral surface of the casing so that it flows toward the exhaust port, thereby discharging air with a high degree of straightness from the exhaust port and suppressing the diffusion of the entire exhaust air (see, for example, Patent Document 2).

[0007] JP 2000-130399 A Japanese Patent No. 6183852 A

[0008] However, in the cooling fan of Patent Document 1 and the axial flow blower of Patent Document 2, although the radial gap between the inner peripheral surface of the casing and the blades is not specifically stated, it is assumed to be a typical gap of 1 mm or less. In this case, soil, sand, oil, or sludge may get into the gap, or water droplets in the gap may freeze in low-temperature environments such as below freezing, and the presence of these foreign objects may inhibit the rotation of the impeller.

[0009] In view of the above, an object of the present invention is to provide a blower that can prevent impeded rotation of the impeller due to the presence of foreign matter and prevent a decrease in fan performance.

[0010] The blower of the present invention comprises a casing having an intake port at one axial end and an exhaust port at the other axial end, an impeller arranged inside the casing and having a plurality of blades, and a plurality of ribs extending from the intake port side to the exhaust port side on the inner surface of the casing and facing the blades, wherein 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.

[0011] 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 of the blower according to this embodiment, which is an example of the present invention, as seen from the intake port side. FIG. 3 is a plan view showing the configuration of the blower according to this embodiment, which is an example of the present invention, as seen from the exhaust port side. FIG. 4 is a plan view showing the number of ribs facing the impeller blades in the blower according to this embodiment, which is an example of the present invention, as seen from the intake port side. FIG. 5 is a table showing the relationship (A) and (B) between the number of ribs and the number of impeller blades in the blower according to this embodiment, which is an example of the present invention. FIG. 6 is a plan view (A) and a partially enlarged perspective view (B) used to explain gaps between 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 blades in the blower according to this embodiment, which is an example of the present invention, and a perspective view (B) showing the width w1 of the tip of the rib. FIG. 8 is a perspective view (A) and a perspective view (B) showing the relationship between adjacent ribs in the blower according to this embodiment, which is an example of the present invention. 1 is a perspective view showing the positional relationship between an intake port and an end of a rib on the intake port side in a blower according to this embodiment which is an example of the present invention, and an angle between the intake port and an end of a rib on the intake port side in a blower according to this embodiment which is an example of the present invention.

[0012] <Embodiment> Hereinafter, an embodiment of the present invention 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 of a blower according to this embodiment, which is an example of the present invention, as viewed from the intake side. Fig. 3 is a plan view showing the configuration of a blower according to this embodiment, which is an example of the present invention, as viewed from the exhaust side. Fig. 4 is a plan view showing the number of ribs facing the impeller blades in a blower according to this embodiment, which is an example of the present invention, as viewed from the intake side.

[0013] Fig. 5 is a table showing the relationship (A) and (B) between the number of ribs and the number of blades of the impeller in a blower according to this embodiment, which is an example of the present invention. Fig. 6 is a plan view (A) and a partially enlarged perspective view (B) for explaining the gaps between the ribs in a 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 blades in a blower according to this embodiment, which is an example of the present invention, and a perspective view (B) showing the width w1 of the tip of the rib.

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

[0015] For convenience of explanation, in the description of this embodiment, the direction of arrow a along the axis X is referred to as one end side or intake port side, and the direction of arrow b along the axis X is referred to as the other end side or exhaust port side. Here, the direction of arrows ab is referred to as the axial X direction. Furthermore, the directions of arrows cd and d are referred to as the radial direction, with the direction of arrow c away from the axis X being referred to as the outer side or one radial side, and the direction of arrow d approaching the axis X being referred to as the inner side or other radial side.

[0016] <Outline of the blower of the present invention> In the blower of the embodiment of the present invention, the narrower the gap between the inner surface of the casing and the impeller blades, the better the static pressure-air volume performance, so an attempt is made to narrow the gap between the inner surface of the casing and the impeller blades as much as possible, but in that case, there is a risk that foreign matter will become trapped in the gap between the inner surface of the casing and the blades, making it impossible to rotate.

[0017] Therefore, the blower of the present invention aims to minimize the narrow areas where foreign matter can get in while maintaining static pressure-air volume performance.To achieve this, the blower of the present invention provides the inner peripheral surface of the casing with multiple ribs that narrow the gap between the inner peripheral surface and the impeller blades, and provides separation areas between adjacent ribs where no such ribs exist to prevent foreign matter from getting in.

[0018] 1 to 4 , the blower 100 according to this embodiment is a fan motor that blows air along an axis X (direction of arrows a and b) from an intake port side (direction of arrow a) to an exhaust port side (direction of arrow b), and has an overall cylindrical shape that is roughly square in a 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 located in the center and a plurality of (in this case, for example, seven) blades 133 that protrude radially outward (in the direction of arrow c) from the outer circumferential surface of the hub 131.

[0020] The impeller 130 is formed by injection molding synthetic resin such as glass fiber-reinforced polybutylene terephthalate, with the hub 131 and the blades 133 being integrally formed. The impeller 130 may also be formed from other materials such as metal.

[0021] At the center of the hub 131, on the exhaust port side (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. The shaft of the motor can be rotatably supported by, but not limited to, a rolling bearing, a sliding bearing, a fluid dynamic bearing, or the like.

[0022] An outer rotor motor consisting of a stator and a rotor is provided in the space inside hub 131. The motor may be, for example, a brushless DC motor. In blower 100, current is supplied sequentially to the stator coils at predetermined timings from a power supply (not shown), thereby rotating the rotor, hub 131 fixed integrally with the rotor, and blades 133.

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

[0024] The blades 133 have a generally trapezoidal shape in a plan view, and are arranged so that their outermost peripheral edges 133s are close to the inner peripheral surface 113n of the impeller accommodating portion 113. The peripheral edges 133s of the blades 133 are arc-shaped and follow the arc-shaped curve of the inner peripheral surface 113n of the impeller accommodating portion 113. Therefore, the distance between the peripheral edges 133s of the blades 133 and the inner peripheral surface 113n of the impeller accommodating portion 113 is uniform. In practice, the gap between the inner peripheral surface 113n of the impeller accommodating portion 113 and the peripheral edges 133s of the blades 133 is set to, for example, 1 mm or less.

[0025] <Casing> Casing 110 of blower 100 has a casing main body 111 formed in a square cylindrical shape in a plan view, and a cylindrical impeller housing portion 113 provided in the center of casing main body 111.

[0026] The casing body 111 and the impeller housing 113 of the casing 110 are integrally formed by injection molding of a synthetic resin such as polybutylene terephthalate reinforced with glass fiber, but the present invention is not limited to this, and the casing 110 may be formed of other metal materials.

[0027] Casing body 111 of casing 110 has through holes 111h at its four corners, through which bolts (not shown) are inserted for attachment to a predetermined device or housing. Impeller accommodating portion 113 of casing 110 is a cylindrical body having an inner diameter large enough to accommodate impeller 130 therein.

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

[0029] In this case, because the casing main body 111 has an even number of spokes 115 (four), the impeller 130 has an odd number of seven blades 133. This is because if the number of spokes 115 and the number of blades 133 were the same, or if the number of blades 133 were an integer multiple of the number of spokes 115, resonance would occur at a specific frequency, generating noise. To prevent this from happening, the number of spokes 115 and the number of blades 133 are not the same or an integer multiple.

[0030] As shown in Figure 2, the impeller accommodating section 113 has an intake port 114 consisting of an inclined surface for introducing air into the inner space of the impeller accommodating section 113 from an opening end surface 113e consisting of a flat, annular end surface on the intake port side (direction of arrow a).

[0031] This air intake port 114 has an annular shape connected to the opening end face 113e, and is an inclined surface that is inclined so that the diameter gradually decreases from the opening end face 113e of the impeller accommodating portion 113 toward the inner circumferential surface 113n of the impeller accommodating portion 113. In other words, the air intake port 114 is a truncated cone surface.

[0032] Impeller housing 113 has an exhaust port at its end on the exhaust port side (arrow b direction). However, the exhaust port is merely a circular end surface 140x (FIG. 10) on inner circumferential surface 113n of impeller housing 113 on the exhaust port side (arrow b direction), and is not a particularly inclined surface like intake port 114.

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

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

[0035] Furthermore, the ribs 140 are inclined so that the entire rib 140 tilts in the direction opposite to the rotation direction (counterclockwise direction indicated by the white arrow) of the impeller 130. In other words, the ribs 140 are inclined from the intake port side (direction of arrow a) to the exhaust port side (direction of arrow b) as they move in the rotation direction of the impeller 130. The ribs 140 are arranged on the inner circumferential surface 113n of the impeller accommodating portion 113 with adjacent ribs 140 parallel to each other.

[0036] <Relationship Between Ribs and Blades> In this case, blower 100 has seven blades 133 on impeller 130 and sixteen ribs 140 on impeller housing portion 113 in casing 110. In this way, blower 100 has, for example, the number of blades 133 made smaller than the number of ribs 140, and made an integer equal to or greater than one-third of the number of ribs 140.

[0037] As a result, in blower 100 ( FIG. 4 ), there are 12 ribs 140 (encircled by dashed circles) that face the peripheral edge 133s of blades 133, and 4 ribs 140 that do not face the peripheral edge 133s of blades 133. However, in blower 100, the number of ribs 140 that face the peripheral edge 133s of blades 133 may vary by approximately one depending on the stopping position of impeller 130.

[0038] In this case, compared to when the radial gap between the ribs 140 and the peripheral edge 133s of the blades 133 is 1 mm or less and the ribs 140 are close to each other over the entire inner circumferential surface 113n of the impeller housing 113, there may be up to 13 ribs 140 that face the peripheral edge 133s of the blades 133 with a radial gap of 1 mm or less. In this case, at least one rib 140 does not face the blade 133 in the radial direction. In this way, the blower 100 can reduce the risk of foreign matter becoming trapped between the rib 140 and the peripheral edge 133s of the blades 133 compared to conventional blower configurations.

[0039] Furthermore, in blower 100, multiple ribs 140 are arranged at regular intervals in the circumferential direction on inner peripheral surface 113n of impeller housing 113, so 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. In other words, the number of ribs 140 facing one blade 133 in the radial direction is two or less, and at least one blade 133 is faced with one rib 140 in the radial direction.

[0040] In other words, in the blower 100, two ribs 140 do not face every blade 133, so the risk of foreign matter getting between the rib 140 and the peripheral edge 133s of the blade 133 can be further reduced.

[0041] Incidentally, the number of blades 133 does not have to be limited to an integer equal to or greater than 1 / 3 of the number of ribs 140, such as seven blades 133 and sixteen ribs 140 of the impeller 130. For example, the number of blades 133 may be twelve blades 133 and twenty ribs 140, or seven blades 133 and twelve ribs 140, such that the number of blades 133 is an integer equal to or greater than half the number of ribs 140.

[0042] The relationship between the number of blades 133 and the number of ribs 140 is not limited to these, and it is sufficient that the number of blades 133 is smaller than the number of ribs 140. In other words, if it is possible to reduce the number of locations where the ribs 140 and the peripheral edges 133s of the blades 133 are arranged to face each other, it is possible to reduce the risk of foreign matter being trapped in the gap between the inner circumferential surface 113n of the impeller accommodating portion 113 and the blades 133 compared to the conventional case. Therefore, the number of blades 133 may be more than or less than one-third, or more than or less than one-half, of 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 multiple ribs 140 that do not face the peripheral edge 133s of the blade 133, the risk of foreign matter becoming trapped between the rib 140 and the peripheral edge 133s of the blade 133 can be reduced.

[0044] Thus, in the blower 100, there are multiple ribs 140 with small gaps between them and the peripheral edges 133s of the blades 133, so that the static pressure-air volume performance can be maintained without any reduction compared to conventional blower 100, and the rotation of the impeller 130 can also be prevented from being inhibited.

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

[0046] This is because if the number of ribs 140 is the same as the number of blades 133, or if the number of ribs 140 is an integer multiple of the number of blades 133, resonance occurs at a specific frequency, resulting in loud noise.

[0047] However, the combination of even numbers and odd numbers, or the combination of odd numbers and even numbers, is not absolute, and as long as noise due to resonance is not generated by, for example, arranging the ribs 140 unevenly on the inner surface 113n of the impeller accommodating section 113, the combination of even numbers and odd numbers or the combination of odd numbers may be used.

[0048] For example, regarding the combination of even and odd numbers, as shown in FIG. 5(A), when the number of ribs 140 is an even number (e.g., 20, 16, or 12), the number of blades 133 can be an odd number (12 (exception), 9, 7, or 5).

[0049] Here, when there are 20 ribs 140 and 12 blades 133, the number of ribs 140 is an even number, but the number of blades 133 is also an even number. This is because, when there are 20 ribs 140, there should be 11 blades 133, which is more than half of that number, but one blade is added to the 11 blades 133 already formed, making the total number 12, and the arrangement of the blades 133 is uneven.

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

[0051] In other words, the blower 100 has fewer blades 133 than ribs 140, and the number of ribs 140 is not the same as the number of blades 133, and the number of ribs 140 is not an integer multiple of the number of blades 133, thereby preventing noise from occurring at specific frequencies.

[0052] For reference, as shown in Figure 5 (A), when there are 20 ribs 140 and 9 blades 133, the number of ribs 140 is an even number, but the number of blades 133 is an odd number. In this case, the number of blades 133 is less than half the number of ribs 140.

[0053] 5A, when there are 16 ribs 140 and 7 or 5 blades 133, the number of ribs 140 is an even number while the number of blades 133 is an odd number, but in this case, when the number of blades 133 is 7, it is more than 1 / 2 of the number of ribs 140, and when the number of blades 133 is 5, it is more than 1 / 3 of the number of ribs 140. Below, the same pattern applies when the number of ribs 140 is 12.

[0054] On the other hand, with regard to combinations of odd and even numbers, as shown in Figure 5 (B), when the number of ribs 140 is an odd number (for example, 21, 15, or 9), combinations in which the number of blades 133 is an even number (12, 8, or 6) are possible.

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

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

[0057] In addition, in blower 100, consideration is given not only to the relationship between the number of ribs 140 and the number of blades 133, but also to the relationship and arrangement between the number of spokes 115 and the number of ribs 140. Specifically, casing main body 111 (FIG. 3) generally has three or four spokes 115, and the number of ribs 140 is an integer multiple of the number of spokes 115.

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

[0059] Therefore, in the blower 100, if the number of ribs 140 is an integer multiple of the number of spokes 115, for example, four spokes 115 and, for example, sixteen ribs 140 can be arranged in a comfortable manner.

[0060] 3, four spokes 115 are provided at equal intervals in the casing main body 111, and four ribs 140 are provided circumferentially between each pair of adjacent spokes 115. This allows the blower 100 to be well-balanced in arrangement such that the spokes 115 and the ribs 140 do not overlap spatially in the axial direction X.

[0061] 6(A) and 6(B), the rib 140 has a mountain-shaped cross section that gradually rises from the inner circumferential surface 113n of the impeller accommodating portion 113 toward the axis X. The rib 140 has a first recess 141 having a concave cross section that gradually rises from the inner circumferential surface 113n of the impeller accommodating portion 113, a convex cross section that is joined to an end 141e of the first recess 141 and serves as a tip that faces the peripheral edge 133s of the blade 133, and a second recess 143 having a concave cross section that is joined to an end 142e of the convex cross section that gradually falls toward the inner circumferential surface 113n of the impeller accommodating portion 113.

[0062] The first recess 141 in the rib 140 is a curved surface that is recessed in an arc shape in cross section. The protrusion 142 in the rib 140 is a curved surface that protrudes in an arc shape in cross section. The second recess 143 in the rib 140, like the first recess 141, is a curved surface that is recessed in an arc shape in cross section.

[0063] Next, as shown in Figures 7(A) and (B), the relationship between the maximum thickness w2 near the peripheral edge 133s of the blade 133 and the circumferential width w1 of the protrusion (tip) 142 of the rib 140 will be described.

[0064] The thickness of the blade 133 is not uniform throughout, but rather gradually becomes thinner from the center of the blade 133 toward the circumferential side edges 133e and 133f, as shown in Figure 7(A), with the central portion having the maximum thickness w2.

[0065] On the other hand, the circumferential width w1 of the protrusion 142 of the rib 140 is the linear distance between the end 141e of the first recess 141 and the end 142e of the protrusion 142 in the circumferential direction. That is, the width w1 of the protrusion 142 at the tip of the rib 140 is the linear distance between the end 141e, which is the first boundary between the first recess 141 and the protrusion 142, and the end 142e, which is the second boundary between the protrusion 142 and the second recess 143. In the blower 100, the width w1 of the rib 140 is constant regardless of the position 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 blower 100, width w1 of protrusion 142 of rib 140 is smaller than maximum thickness w2 of blade 133. As a result, in blower 100, although the radial gap between protrusion 142 of rib 140 and peripheral edge 133s of blade 133 is close at 1 mm or less, the range (area) over which rib 140 and blade 133 face each other in the circumferential direction is smaller, thereby further reducing the risk of foreign matter becoming trapped in the gap between them.

[0067] As shown in Figure 6, the area between the convex portion 142 of one rib 140 and the convex portion 142 of the other rib 140 that are adjacent to each other in the circumferential direction is a portion that includes the inner surface 113n of the impeller accommodating portion 113, but in order to distinguish this area from the ribs 140, the area between the convex portion 142 of one rib 140 and the convex portion 142 of the other rib 140 will be called a separation portion 145.

[0068] The plurality of spaced portions 145 in the impeller accommodating portion 113 have a length D1 ( FIG. 7B ) that is a length that connects an end portion 141 e of one rib 140 with an end portion 142 e of the other rib 140 that is adjacent to the end portion 141 e in the forward direction of the rotation of the impeller 130. In other words, it can also be said that the length D1 is the length between the protrusion 142 of one rib 140 and the protrusion 142 of the other rib 140.

[0069] The multiple gaps 145 present on the inner surface 113n of the impeller accommodating section 113 are alternately arranged due to the presence of multiple ribs 140, and their circumferential length D1 is longer than the width w1, i.e., the circumferential length, of the convex portion 142 of the rib 140.

[0070] In this case, the area of ​​the inner circumferential surface 113n of the impeller accommodating portion 113 occupied by the separation portions 145 between the plurality of ribs 140 is 70% or more of the entire area. However, this is not limited to this, and the area occupied by the separation portions 145 may be 80% or more, or 90% or more of the entire area by reducing the number of ribs 140 or by reducing the width w1 of the protrusions 142 of the ribs 140.

[0071] Incidentally, in the rib 140, it is preferable that the minimum radial gap between the ridge portion 142s (Figures 6 and 7) that forms the top of the convex portion 142 and the peripheral edge 133s of the blade 133 is 1 mm or less, and that the radial distance between the peripheral edge 133s of the blade 133 and the inner surface 113n of the impeller accommodating portion 113 is 3 mm or more.

[0072] The reason for this is that if the radial gap between the peripheral edge 133s of the blades 133 is 1 mm or less, it is possible to prevent a decrease in static pressure-air volume performance, as in the conventional case. Also, if the radial gap between the peripheral edge 133s of the blades 133 and the inner circumferential surface 113n of the impeller accommodating portion 113 is 3 mm or more, it is possible to reduce the risk of foreign matter getting caught in the gap, and to prevent the rotation of the impeller 130 from being inhibited.

[0073] As shown in Figure 8 (A), two adjacent inclined ribs 140 are arranged parallel to each other on the inner surface 113n of the impeller accommodating section 113, but it is preferable to make the circumferential spacing between the ribs 140 even closer.

[0074] The reason for this is that if the spacing between the ribs 140 in the blower 100 is large, the air flowing from the intake port side to the exhaust port side by the blades 133 of the impeller 130 may flow backward.

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

[0076] However, when forming the multiple ribs 140 in the impeller accommodating portion 113 of the casing 110 by injection molding, it is necessary to take into consideration the fact that the casing 110 will be extracted as a molded product from the mold. Therefore, in this 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 direction of axis X (in the direction of arrows ab).

[0077] 9, the multiple ribs 140 protrude toward the blades 133 of the impeller 130 and face peripheral edges 133s of the blades 133. However, while the ribs 140 extend forward in the rotation direction of the impeller 130 from the intake port side (direction of arrow a) toward the exhaust port side (direction of arrow b), the peripheral edges 133s of the blades 133 extend obliquely backward in the rotation direction of the impeller 130 from the intake port side (direction of arrow a) toward the exhaust port side (direction of arrow b), so the ribs 140 and the blades 133 face each other and intersect with each other.

[0078] Furthermore, the top portion (the portion surrounded by the dashed circle in Figure 9) of the peripheral edge 133s of the blade 133 on the intake port side (direction of arrow a) faces the intake port 114 of the impeller accommodating section 113, but does not face the rib 140.

[0079] That is, most of the peripheral edge 133s of the blade 133 faces the rib 140, but the top (portion surrounded by the dashed circle) of the peripheral edge 133s of the blade 133 on the intake port side (direction of arrow a) does not face the rib 140, but faces only the intake port 114 of the impeller housing 113. This prevents the inflow of air from being impeded to that extent in the blower 100, thereby suppressing a decrease in the static pressure-air volume performance of the blower 100. At the same time, the blower 100 also reduces the area between the rib 140 and the blade 133 where foreign matter may be trapped.

[0080] Furthermore, as shown in Figure 10, the inclined end face 140t on the intake port side (direction of arrow a) of the rib 140 is inclined from the intake port side (direction of arrow a) toward the exhaust port side (direction of arrow b), and is connected flush with the inclined intake port 114 in the impeller accommodating section 113.

[0081] Specifically, the intake port 114 of the impeller accommodating section 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 intake port side (direction of arrow a) toward the exhaust port side (direction of arrow b).

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

[0083] Incidentally, the end face 140x of the rib 140 on the exhaust port side does not need to be inclined with respect to the horizontal direction perpendicular to the axial X direction (arrow ab direction) because it serves as an exhaust port and does not draw air therethrough.

[0084] In the above configuration, the blower 100 has a plurality of ribs 140 that face the blades 133 on the inner surface 113n of the impeller accommodating section 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 positioned opposite the blades 133 of the impeller 130.

[0085] As a result, in the blower 100, the presence of the multiple ribs 140 can suppress a decrease in the static pressure-air volume performance of the impeller 130, and it is possible to avoid a situation where all of the multiple ribs 140 are positioned opposite the peripheral edge 133s of the blades 133, thereby significantly reducing the risk of foreign matter becoming trapped in the gap between the ribs 140 and the blades 133 compared to conventional cases.

[0086] Furthermore, in the blower 100, the area of ​​the inner surface 113n of the impeller accommodating section 113 occupied by the separation sections 145 between the multiple ribs 140 is at least 70% of the total area, and by increasing the area that does not face the ribs 140, the risk of foreign matter getting caught in the gap between the ribs 140 and the blades 133 can be significantly reduced compared to conventional cases.

[0087] In particular, in the case of blower 100, in low-temperature environments such as below freezing (for example, around minus 20 degrees), ice may freeze and become trapped as foreign matter between ribs 140 provided on the inner surface 113n of impeller accommodating section 113 and the peripheral edge 133s of blades 133, but since there are few points where ribs 140 and blades 133 face each other and the facing area is small, it is possible to rotate impeller 130 using a motor, thereby preventing malfunctions.

[0088] Other Embodiments Although the blower of the present invention has been described above with reference to preferred embodiments, the blower of the present invention is not limited to the configuration of blower 100 disclosed in the above embodiment. In the above embodiment, the case where rib 140 having a protruding mountain-shaped cross section is provided on inner circumferential surface 113n of 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, or an arc cross section, may also be provided.

[0089] In addition, in the embodiment of the present invention, the radial gap between the rib 140 and the peripheral edge 133s of the blade 133 is described as being 1 mm or less, and the radial distance between the inner surface 113n of the impeller accommodating portion 113 and the peripheral edge 133s of the blade 133 is described as being 3 mm or more.

[0090] However, the present invention is not limited to this, and various combinations may be set, such as setting the radial gap between the rib 140 and the peripheral edge 133s of the blade 133 to 1 mm or less and the radial distance between the inner surface 113n of the impeller accommodating section 113 and the peripheral edge 133s of the blade 133 to less than 3 mm when prioritizing static pressure-air volume performance in the trade-off relationship between static pressure-air volume performance and the risk of foreign matter getting in the way, or setting the radial gap between the rib 140 and the peripheral edge 133s of the blade 133 to 1 mm or more and the radial distance between the inner surface 113n of the impeller accommodating section 113 and the peripheral edge 133s of the blade 133 to 3 mm or more when prioritizing preventing foreign matter getting in the way.

[0091] In addition, those skilled in the art can appropriately modify the blower of the present invention and change the combination of various components in accordance with conventional knowledge. As long as such modifications still include the components of the present invention, they are of course included in the scope of the present invention.

[0092] 100...blower, 110...casing, 111...casing main body, 111h...through hole, 113...impeller accommodating section, 113e...opening end surface, 113n...inner peripheral surface, 114...air intake port, 115...spokes, 116...support plate, 130...impeller, 131...hub, 133...blade, 133e, 133f...side edge, 133s...peripheral edge, 140...rib, 140t...end surface, 140x...end surface, 141...first recess, 141g...end, 142...protruding portion 142 (tip), 142s...ridge portion, 143...second recess, 143g...end, 145...separation portion, D1...length, w1...width, w2...maximum thickness.

Claims

1. A blower comprising: a casing having an intake port at one axial end and an exhaust port at the other axial end; an impeller arranged inside the casing and having a plurality of blades; and a plurality of ribs provided on the inner peripheral surface of the casing so as to extend from the intake port side to the exhaust port side and facing the blades, wherein the number of the blades is less than the number of the ribs, and the number of the ribs is a non-integer multiple of the number of the blades.

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

3. The blower according to claim 1 or 2, wherein the number of said ribs facing each of said blades is two or less.

4. The blower according to claim 3, wherein at least one of the blades has one rib opposed thereto in the radial direction.

5. The blower according to claim 1, wherein the width of the tip of each of the ribs that faces the blade is smaller than the maximum thickness of the blade.

6. A blower as claimed in claim 1, wherein said rib has a mountain-shaped cross section that rises gradually from the inner peripheral surface of said casing, and has a first recess rising from said inner peripheral surface, a convex portion joined to an end of said first recess, and a second recess joined to said convex portion and rising down towards said inner peripheral surface.

7. A blower as described in claim 6, wherein the width of the tip of the rib is a straight-line distance connecting a first boundary line that is the boundary between the first recess and the protrusion, and a second boundary line that is the boundary between the protrusion and the second recess, and a separation portion is formed between the protrusions of the ribs that are 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.

8. The blower according to claim 7, wherein an area of ​​the inner circumferential surface of the casing that is occupied by the separated portion is 70% or more of the entire inner circumferential surface.

9. A blower as described in claim 1, wherein the ribs extend at an angle from the intake port side to the exhaust port side, and the end of one adjacent rib on the intake port side spatially overlaps with the end of the other adjacent rib in the axial direction.

10. The blower according to claim 1, wherein the end of the rib on the intake port side has an end face that is continuous with an inclined surface that forms the intake port in the casing.

11. The blower according to claim 1, wherein the number of the blades is an integer equal to or greater than 1 / 3 of the number of the ribs.

12. The blower according to claim 11, wherein the number of the blades is an integer equal to or greater than half the number of the ribs.

13. A blower as claimed in claim 1 or 7, wherein the casing has a plurality of spokes for rotatably supporting the impeller, and when the number of the spokes is an even or odd number, the number of the ribs is also an even or odd number.

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