US20180023587A1

US20180023587A1 - Centrifugal Fan

Info

Publication number: US20180023587A1
Application number: US15/643,777
Authority: US
Inventors: Takako OTSUKA
Original assignee: MinebeaMitsumi Inc
Current assignee: MinebeaMitsumi Inc
Priority date: 2016-07-19
Filing date: 2017-07-07
Publication date: 2018-01-25

Abstract

There is provided a centrifugal fan capable of minimizing variations of the vent flow amount of the gas in the direction of the height of the vent.

The centrifugal fan 1 of the present invention includes a housing 10 including an intake port 11 a and an impeller 20 arranged inside the housing 10, including a base part 21 and a plurality of vanes 25, wherein the intake port 11 a takes in gas on one end portion side in the rotary axis direction 33, a face of the base part 21 on a side of the intake port 11 a includes a gradient face 22 inclined toward a rotary shaft 33 and the intake port 11 a, the plurality of vanes 25 are provided at the gradient face 22, and the width of the vanes 22 in the radial direction is increased from the intake port 11 a side toward the gradient face 22.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Applications No. 2016-141811 and No. 2016-141813, both filed on Jul. 19, 2016, which are hereby incorporated by reference in their entirety.

BACKGROUND

Technical Field

The present invention relates to a centrifugal fan.

Background

Conventionally, a centrifugal fan has been known, in which an impeller provided in a housing is rotated by a motor, thereby to take in gas from an intake port for taking in gas such as air provided on an upper face or lower face of the housing and to send out the taken-in gas from a vent provided on a side of the housing (see Japanese Patent Laid-Open No. 2013-53634).
Incidentally, for a centrifugal fan, an impeller whose height is comparatively lower with respect to its diameter is used, and the height of the vent of the housing is also approximately equal to or slightly higher than the height of the impeller.
If a higher vent is required, the height of the impeller is to be increased as the height of the vent is increased. However, merely increasing the height of the impeller in response to the height of the vent causes a problem and does not lead to a uniform vent flow amount of the gas in the direction of the height of the vent.
With the above circumstances taken into consideration, the object of the present invention is to provide a centrifugal fan capable of minimizing variations of the vent flow amount of the gas in the direction of the height of the vent.

SUMMARY

In order to achieve the above object, it is understood that the present invention has the following configurations.
(1) The centrifugal fan according to the present invention comprises a housing including an intake port, and an impeller arranged inside the housing, including a base part and a plurality of vanes, wherein the intake port takes in gas on one end portion side in the rotary axis direction, a face of the base part on a side of the intake port comprises a gradient face inclined toward a rotary shaft and the intake port, the plurality of vanes are provided at the gradient face, and the width of the vanes in the radial direction is increased from the intake port side toward the gradient face.
(2) In the above configuration (1), the ratio H/W is equal to or larger than 0.55, wherein H [mm] is a length of the impeller in the rotary axis direction and, W [mm] is a length of the impeller in the radial direction.
(3) In the above configuration (1) or (2), the length of the impeller in the radial direction is from 30 mm to 110 mm.
(4) In any one of the above configurations (1) to (3), D2 is equal to or smaller than D1×0.9, wherein D1 [mm] is a distance of the inner shape of the inside of the plurality of vanes on the intake port side and, D2 [mm] is a distance of the inner shape of the inside of the plurality of vanes on the base part side.
(5) In the above configuration (4), the distance D2 [mm] is equal to or larger than the distance D1×0.4 [mm].
(6) In any one of the above configurations (1) to (5), the height of the top portion of the gradient face is smaller than a height of the center of the impeller.
(7) In any one of the above configurations (1) to (6), the vanes have an identical curvature radius in the rotary axis direction and the inner end portion of the vane extends consecutively from the intake port side to the base part side in the radial direction.
(8) In any one of the above configurations (1) to (7), the impeller has a ring part coupling end portions of the plurality of vanes on the intake port side and the outer peripheral part of the base part is inside the inner peripheral part of the ring part in the radial direction.
(9) In any one of the above configurations (1) to (8), the outer peripheral part of the plurality of vanes extends in the rotary axis direction.
(10) In any one of the above configurations (1) to (9), comprising a motor including a rotary shaft coupled with the impeller, wherein the base part comprises a first face on the intake port side and a second face opposite side to the first face, and the second face is a gradient face.
According to the present invention, it is possible to provide a centrifugal fan capable of minimizing variations of the vent flow amount of the gas in the direction of the height of the vent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a centrifugal fan according to the first embodiment of the present invention.

FIG. 2 is a perspective view showing a centrifugal fan with a cover part removed according to the first embodiment of the present invention.

FIG. 3 is a top view showing an impeller seen from a side which serves as the intake port side according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing an impeller seen from the direction B, which is cut along the A-A line shown in FIG. 3.

FIG. 5 is a top view showing a motor for rotating an impeller of a centrifugal fan according to the first and second embodiments of the present invention.

FIG. 6 is a perspective view showing a centrifugal fan according to the second embodiment of the present invention.

FIG. 7 is a perspective view showing a centrifugal fan with a cover part removed according to the second embodiment of the present invention.

FIG. 8 is a top view showing an impeller seen from a side which serves as the intake port side according to the second embodiment of the present invention.

FIG. 9 is a sectional view showing an impeller seen from the direction B, which is cut along the A-A line shown in FIG. 8.

FIG. 10 is a top view showing a centrifugal fan seen from the intake port side according to the first embodiment of the present invention.

FIG. 11 is a sectional view for explaining a variation of an impeller according to the second embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, the first embodiment of the present invention will be explained in detail on the basis of FIGS. 1 to 5, and the second embodiment of the present invention will be explained in detail on the basis of FIGS. 5 to 11.
The same components have the same reference numerals throughout the entire explanation regarding the embodiments.

First Embodiment

FIG. 1 is a perspective view showing a centrifugal fan 1 according to the first embodiment of the present invention.
The arrow T in FIG. 1 indicates a rotary direction of an impeller 20, and a Z-axis indicates a rotary axis direction.
As shown in FIG. 1, the centrifugal fan 1 comprises a housing 10 with an intake port 11 a on the one end portion side in the rotary axis direction Z, for taking in gas such as air and an impeller 20 contained in the housing 10.

(Housing)

The housing 10 comprises a bottom part 12 and a cover part 11 covering the impeller 20 arranged on the bottom part 12.
The cover part 11 has a cover 11 b with an inner peripheral part forming an opening and a side wall part 11 c enclosing an outer peripheral part of the impeller 20 along the outer periphery of the cover 11 b.
The opening formed in the inner peripheral part of the cover 11 b is the intake port 11 a, and is formed in the shape of a circle.
Further, the housing 10 has a vent 13.
The vent 13 is formed by a part of the cover part 11 extending in the circumferential direction and a part of the bottom part 12.
In the peripheral direction, the part of this cover part 11 extends from a part of the impeller 20 in the direction orthogonal to the rotary axis direction Z.
FIG. 2 is a perspective view showing the centrifugal fan 1 with the cover part 11 removed.
In FIG. 2 as well, the arrow T indicates the rotary direction of the impeller 20, as in FIG. 1.
As shown in FIG. 2, the bottom part 12 has a step part 12 a along the outer shape of the cover part 11.
This step part 12 a is formed by being lowered by one step inwards from the outer peripheral part of the bottom part 12.
This step part 12 a is provided to facilitate positioning when attaching the cover part 11.
Further, the bottom part 12 has a hole part 12 b. A screw passes through the hole part 12 b at the time of fixing the cover part 11 to the bottom part 12.
Meanwhile, as shown in FIG. 1, the cover part 11 has a fixing part 11 d provided integrally with the side wall part 11 c so that the fixing part 11 d extends outwards from the side wall part 11 c.
This fixing part 11 d is provided with a hole part 11 da corresponding to the hole part 12 b.
The cover part 11 is arranged on the bottom part 12, so that the hole part 11 da of the cover part 11 is positioned on or above the hole part 12 b of the bottom part 12.
Thus, a screw (or a bolt is also useful) is formed to pass through the hole part 12 b of the bottom part 12 and the hole part 11 da of the cover part 11, thereby to screw a nut with the tip of the screw, so that the cover part 11 can be fixed to the bottom part 12.
It is also possible to spirally form a groove beforehand, with which a screw is screwed, on the inner peripheral face of the hole part 12 b of the bottom part 12, and to screw a screw in the hole part 12 b, thereby to fix the cover part 11 with respect to the bottom part 12.

(Impeller)

As shown in FIG. 2, the impeller 20 comprises a base part 21 and a plurality of vanes 25.
The face of the base part 21 on the side of the intake port 11 a is a gradient face 22 (see FIG. 4) inclined toward the rotary shaft and the intake port 11 a.
The base part 21 is arranged opposite the intake port 11 a (see FIG. 1) of the housing 10.
Further, the plurality of vanes 25 are provided at the face (see the gradient face 22 in FIG. 4) of the base part 21 as the side of the intake port 11 a, and are provided in the rotary direction.
FIG. 3 is a top view showing the impeller 20 seen from the side of the intake port 11 a, and FIG. 4 is a sectional view showing the impeller 20 seen from the direction B, which is cut along the A-A line in FIG. 3.
The upper side in FIG. 4 is the side of the intake port 11 a of the housing 10.
In the impeller 20, the ratio H/W is equal to or larger than 0.55, where H [(mm] is its length in the rotary axis direction Z (see FIG. 1) and W [mm] is its length in the radial direction.
Concretely, as shown in FIG. 4, the length W [mm] of the impeller 20 in the radial direction is from 30 mm to 110 mm (for example, the length W [mm] in the radial direction is about 70 mm), and the ratio H/W obtained by dividing the length H [mm](hereinafter, this length of the impeller 20 in the rotary axis direction Z is regarded as the direction of height) of the impeller 20 in the rotary axis direction Z by the length W [mm] in the radial direction is about 0.6.
The height of the impeller 20 in the present embodiment is larger than the height of the impeller with the ratio H/W of less than 0.5, and the height of the vent 13 is increased correspondingly.
The length W [(mm] of the impeller 20 in the radial direction is approximately equal to the outer diameter (the diameter of the circle formed by connecting the respective outer end portions of the plurality of vanes 25) of the outer peripheral part 25 c connecting the outer end portions of the plurality of vanes 25 in the radial direction (as to the outer peripheral part 25 c, see FIG. 2).
Further, the outer diameter of this plurality of vanes 25 is substantially identical at any position in the height direction of the impeller 20. Concretely, the difference in outer diameter among the plurality of vanes 25 is +5% as the upper limit and −5% as the lower limit with respect to the size of a predetermined outer diameter, while the difference is preferably within a range between +5% as the upper limit and −5% as the lower limit.
Hereinafter, the respective components of the impeller 20 will be explained more concretely.
As shown in FIG. 4, the base part 21 comprises an annular part 21 a, a gradient part 21 b and a fixing part 21 c.
The annular part 21 a, the gradient part 21 b and the fixing part 21 c are connected integrally.
The annular part 21 a is arranged on the outer peripheral part side of the base part 21.
The inclined part 21 b extends from the inner peripheral part of the annular part 21 a to the center, while the inclined part 21 b is inclined toward the intake port 11 a (see the upper side in FIG. 4) of the housing 10.
The fixing part 21 c is arranged on the most central side (the center of the base part) with respect to the annular part 21 a.
Further, the fixing part 21 c is used for fixing a rotary shaft 33 of a motor 30 (see FIG. 5).
The base part 21 may be formed by the gradient part 21 b arranged on the outer peripheral part side of the base part 21 and the fixing part 21 c arranged at the center of the base part, with the annular part 21 a omitted.
At the center part of the fixing part 21 c, there is provided a hole part 21 ca, into which the rotary shaft 33 (see FIG. 5) of the motor 30 (see FIG. 5) is inserted.
Into this hole part 21 ca, the rotary shaft 33 of the motor 30 is inserted and fixed.
The rotary shaft 33 of the motor 30 fixed to the fixing part 21 c rotates to rotate the impeller 20 with the fixing part 21 c.
The plurality of vanes 25 comprises a first face 25 a for receiving gas and a second face 25 b opposite the first face 25 a in the rotary direction, while the first face 25 a and the second face 25 b are opposed to each other between the adjacent vanes 25.
As shown in FIG. 4, the width of the first face 25 a of the plurality of vanes 25 in the radial direction is increased from the side of the intake port 11 a (the upper side in FIG. 4) of the housing 10 toward the side of the base part 21, and the area of the first face 25 a for receiving gas is comparatively large.
In the present embodiment, as shown in FIG. 4, the second face 25 b also has an area that increases from the side of the intake port 11 a (the upper side in FIG. 4) of the housing 10 toward the side of the base part 21.
D2 [mm] is equal to or smaller than D1×0.9 [mm], where D1 [mm] is the longest distance of the inner shape for connecting the inner end portions of the plurality of vanes 25 on the side of the intake port 11 a (hereinafter referred to as the inner shape D1 [mm] in a certain case), and D2 [mm] is the longest distance of the inner shape for connecting the inner end portions of the plurality of vanes 25 on the side of the base part 21 (hereinafter referred to as the inner shape D2 [mm] in a certain case).
In the present embodiment, as shown by the dot-line circle X in FIG. 3, the inner shape formed by connecting the inner end portions of the plurality of vanes 25 on the side of the intake port 11 a is a circle.
In this way, the distance D1 [mm] is the diameter of the inner peripheral part connecting the inner end portions of the plurality of vanes 25 on the side of the intake port 11 a.
Similarly, as shown by the dot-line circle Y in FIG. 3, the inner shape formed by connecting the inner end portions of the plurality of vanes 25 on the side of the base part 21 is a circle.
In this way, the distance D2 [mm] is the diameter of the inner peripheral part connecting the inner end portions of the plurality of vanes 25 on the side of the base part 21.
A more specific explanation will be made below. As shown in FIG. 3, when seen from the side which serves as the side of the intake port 11 a of the housing 10 (top viewing), the intake port side inner diameter (the inner diameter of the circle X drawn by the dotted line) for connecting the respective inner peripheral parts of the plurality of vanes 25 on the side of the intake port 11 a is called D1 [mm] (see FIG. 4), and the base part side inner diameter (the inner diameter of the circle Y drawn by the dotted line) for connecting the respective inner peripheral parts of the plurality of vanes 25 on the side of the base part 21 is called D2 [mm] (see FIG. 4).
The base part side inner diameter D2 [mm] is set to be equal to or smaller than the intake port side inner diameter D1×0.9 [mm].
Further, from the side of the intake port 11 a toward the side of the base part 21, the width of the first face 25 a of the vane 25 in the radial direction is configured to be increased.
In the present embodiment, from the side of the intake port 11 a toward the side of the base part 21, the width of the second face 25 b of the vane 25 in the radial direction is also configured to be increased.
In the rotary axis direction, the width (in the radial direction) of the end portions of the vanes 25 on the side of the base part 21 is larger than the width (in the radial direction) of the end portions of the vanes 25 on the side of the intake port 11 a, and further the width (in the radial direction) of the end portions of the vanes 25 on the side of the base part 21 is larger than the width (in the radial direction) of the vanes 25 at the intermediate position between the intake port 11 a and the base part 21.
For example, one example where the length W [mm] in the radial direction of the impeller 20 is about 70 mm is assumed. When the intake port side inner diameter D1 [mm] is about 60 mm and the base part side inner diameter D2 [mm] is about 46 mm, the relationship between the base part side inner diameter D2 [mm] and the intake port inner diameter D1 [mm] is: D2 [mm]=D1×0.77 [mm].
Further, as shown in FIG. 4, the end portions of the vanes 25 on the side of the base part 21 are provided on the gradient face 22 of the base part 21.
As described above, by increasing the intake port side inner diameter D1, the area of the vane 25 of the impeller 20 on the side of the intake port 11 a of the housing 10 for receiving the gas is decreased, while the width (on the intake port side) of the internal space provided inside the plurality of vanes 25 is increased.
Moreover, by decreasing the base part side inner diameter D2, the area of the vane 25 for receiving the gas is increased toward the side of the base part 21, while the width (on the base part side) of the internal space inside of the plurality of vanes 25 is decreased.
Due to the above configuration, since the width of the internal space on the side of the intake port 11 a is large, the gas flowing can pass through the internal space without being taken into the housing 10 on the way to reach the side of the base part 21, so that the gas can be taken into the housing 10 on the side of the base part 21.
Namely, a part of the gas passing through the center of this internal space is not taken into the housing 10 by the vanes 25 and flows to the side of the base part 21.
Further, combined with the configuration where the width (in the radial direction) of the vanes 25 on the side of the base part 21 is larger than the width (in the radial direction) of the vanes 25 on the side of the intake port 11 a, the suction force for suctioning the gas becomes more intense from the side of the intake port 11 a toward the side of the base part 21. Therefore, the gas can be successfully taken to the side of the base part 21.
Further, as the width (in the radial direction) of the internal space becomes smaller toward the side of the base part 21, the gas flowing in the internal space is successively taken into the housing 10 by the vanes 25.
Further, on the side of the base part 21, the gas is smoothly guided along the gradient face 22 to the side of the vanes 25, and therefore the gas is efficiently taken into the housing 10 on the side of the base part 21.
Therefore, even if the height of the impeller 20 is comparatively large, the gas is suctioned up to the side of the base part 21 and the gas can be sufficiently taken into the housing 10 from the side of the base part 21, so that the internal pressure inside the housing 10 is made uniform in the rotary axis direction and the gas flowing through the housing 10 blows from the vent 13 not in a one-sided manner, but in a uniform manner.
Meanwhile, in the centrifugal fan where the height of the impeller is merely increased, the greater the height of the impeller becomes, the more insufficient the suction force for taking in the gas up to the base part side in the internal space is.
Due to this, the gas flowing through the internal space to reach the base part side is disadvantageously taken into the housing by the vanes, so that, in some cases, the gas for being taken into the housing runs short on the base part side.
In this case, the gas is not sufficiently taken to the bottom side in the housing, and the internal pressure on the bottom side in the housing is lowered.
Further, in the centrifugal fan, the distance from the housing, into the housing the gas being taken, to the vent for blowing the gas is not far.
Moreover, the gas is released at the vent and the flow velocity of the gas is lowered as the gas nears the vent.
With these circumstances combined with each other, the gas leans to the bottom side of the housing based on the distribution of the internal pressure and, then, the gas is to blow out from the vent.
In this manner, at the vent, the blow flow rate of the gas increases toward the bottom side.
Thus, by realizing the configuration of the impeller 20 in the present embodiment, even if the impeller 20 is tall, the internal pressure inside the housing 10 in the rotary axis direction can be formed uniform and it is possible to prevent the above-mentioned problem such that the gas blows out from the vent more on the bottom side of the housing if the height of the impeller is merely increased.
Further, the base part side inner diameter D2 [mm] is preferably equal to or larger than the intake port side inner diameter D1×0.4 [mm] in that the gas can be taken up to the side of the base part 21.
From the viewpoint of preventing the intake amount of the gas from running short too much, D1 [mm] is preferably equal to or larger than W×0.7 [mm], where D1 [mm] is the intake port side inner diameter for connecting the insides of the plurality of vanes 25 on the side of the intake port 11 a of the housing 10 and W [mm] is the length in the radial direction of the impeller 20.
Further, as shown in FIG. 4, the gradient face 22 of the base part 21 is preferably configured such that the position h of the top portion in the rotary axis direction, nearest to the side of the intake port 11 a of the housing 10 lies under the central MH of the impeller 20 to prevent the internal space on the side of the base part 21 from becoming too small.
Meanwhile, even if the vent 13 is required to be higher in a centrifugal fan, the height of the centrifugal fan itself needs to be low and therefore the height of the centrifugal fan as a whole needs to be lowered as much as possible.
Then, as shown in FIG. 4, the gradient part 21 b between the annular part 21 a and the fixing part 21 c of the base part 21 may be configured such that the rear face (second face) arranged opposite the gradient face 22 (first face) is also a gradient face 23 with a substantially identical inclination as that of the gradient face 22. As a case of having the substantially identical inclination, for example, the difference between the gradient angle of the gradient face 23 and the gradient angle of the gradient face 22 lies within the ranges of e.g. +5% as an upper limit and −5% as a lower limit.
Specifically, as shown in FIG. 5, a face 31 of the motor 30 (a face 31 of a motor body part 32) facing the base part 21 is formed to be along the gradient face 23 which is a rear face of the base part 21. Further, at least a part or the whole of the motor body part 32 is contained in the space inside of the gradient part 21 b of the base part 21.
By the above-described configuration, the height of the whole centrifugal fan 1 including the motor 30 is preferably reduced.
The concrete drive mechanism of the motor 30 is identical to that of a general motor, and the motor body part 32 includes a stator and a rotor for configuring a motor driving part. As shown in FIG. 5, the rotary shaft 33 of the rotor is derived from the center of the face 31 of the motor body part 32 facing the base part 21 and, from the part of the motor body part 32 opposite this side for the rotary shaft 33 being derived, a pair of power supply terminals 34 is derived to supply electric power to the motor 30.
As explained with reference to FIG. 4, the rotary shaft 33 of the rotor is fixed to the hole part 21 ca of the fixing part 21 c provided on the central side of the base part 21.
The method for fixing the rotary shaft 33 to the hole part 21 ca is not particularly limited. For example, it is possible to form a screw groove in the hole part 21 ca and form a screw groove screwing with the screw groove at the tip of the rotary shaft 33. Moreover, press-fitting as well as adhesion-fitting may be adopted.
The shape, etc. of the impeller 20 has been concretely explained in detail so far. From the viewpoint of the manufacturing costs, the impeller 20 is preferably configured in such a manner that the base part 21 and the vanes 25, etc. are integrally molded by a material such a resin. When the impeller 20 is produced by injection molding and the like, it is necessary to consider beforehand the shape of the impeller 20 which can be removed after molding from the mold used for the integral molding. Hereinafter, the shape of the impeller 20 based on this viewpoint will be explained.
As described above, the height of the impeller 20 in the present embodiment is large and therefore the vanes 25 may be deformed in some cases due to wind pressure.
In order to prevent such deformation, as shown in FIG. 2, the impeller 20 according to the present embodiment has a ring part 26 connecting the outer peripheral sides of the end portions of the plurality of vanes 25 on the side of the intake port 11 a of the housing 10.
However, when the ring part 26 and the base part 21 are arranged so that they overlap each other, designing a mold becomes difficult.
Then, as shown in FIGS. 3 and 4, the outer periphery 24 (outer peripheral part) of the base part 21 is arranged nearer to the central side (the inside in the radial direction) than the inner periphery 26 a (inner peripheral part) of the ring part 26.
Namely, the outer diameter of the base part 21 is designed smaller than the inner diameter of the ring part 26.
Further, as clarified in FIG. 3, the vanes 25 are configured in such a manner that the inner end portions 27 of the vanes 25 as the inside of the impeller 20 are arranged nearer to the center toward the side of the base part 21 and are consecutively connected from the side of the intake port 11 a to the side of the base part 21, for increasing the area of the vanes 25 for receiving the gas, in order to maintain the same curvature radius as the section of the vanes 25 on the side of the intake port 11 a of the housing 10.
Namely, the vanes 25 have a substantially identical curvature radius at any position in the height direction of the impeller 20, and the vanes 25 have the inner end portions 27 as the inside of the impeller 20 consecutively connected from the side of the intake port 11 a of the housing 10 toward the side of the base part 21 in the radial direction. As the substantially identical curvature radiuses, for example, the difference between the curvature radius of the vanes 25 on the side of the intake port 11 a and the curvature radius of the vanes 25 on the side of the base part 21 is within the range of +5% as the upper limit and −5% as the lower limit.
Then, the vanes 25 have an approximately equal thickness at any position in the height direction of the impeller 20, and all the vanes 25 are designed in the same manner, so that the pitches on the base part 21 in the rotary direction are approximately equivalent to each other. As an example in which the thicknesses are approximately equal to each other or the pitches are almost equal to each other, the difference between the thicknesses and the difference between the pitches are within the ranges of +5% as the upper limit and −5% as the lower limit.
By adopting the above configuration, after two molds, i.e. a first mold provided on the side of the intake port 11 a of the housing 10 and a second mold provided on the side of the base part 21 are put together and resin is injected into these molds to mold the impeller 20, there is nothing interfering with the molds in the removal direction (for example, the direction of the intake port 11 a for the first mold and the direction of the base part 21 for the second mold) at the time of removing the first and second molds, so that the molds can be successfully removed.
Thus, from the viewpoint of moldability, it is preferable that the vanes 25 have the approximately same curvature radius at any position in the height direction of the impeller 20, and the inner end portions 27 as the inside of the impeller 20 are consecutively connected from the side of the intake port 11 a of the housing 10 toward the side of the base part 21, while the outer diameter of the base part 21 is smaller than the inner diameter of the ring part 26.
However, if the ring part 26 is manufactured beforehand as a separate component and is ultrasonic-welded later to connect the vanes 25, the outer diameter of the base part 21 does not need to be smaller than the inner diameter of the ring part 26. If the impeller 20 is manufactured without performing the integral molding as described above, the above configuration does not necessarily need to be adopted.

Second Embodiment

The centrifugal fan of the second embodiment differs from the centrifugal fan of the first embodiment in that the centrifugal fan of the second embodiment comprises first and second rings. Hereinafter, the second embodiment will be explained and, in the second embodiment, explanation about the same configurations as those in the first embodiment will be omitted.
The vanes 25 of the centrifugal fan 1 are formed to extend from the base part 21 to the intake port 11 a (the upper side in FIG. 9), while the centrifugal force and the wind pressure applying to the vanes 25 work in the direction crossing the extending direction (rotary axis direction Z) of the vanes 25 and therefore work as a force deflecting the vanes 25.
In order to prevent deflection from occurring in the vanes 25 due to the above force deflecting the vanes, as shown in FIGS. 8 and 9, the first ring part 26 for annularly connecting the end portions of the vanes 25 is provided at the end portions of the vanes 25 arranged opposite the base part 21.
This first ring part 26 connects the end portions of the plurality of vanes 25.
In this manner, it is difficult for deflection to occur at the vanes 25 and damage to the vanes 25 does not occur readily.
As shown in FIG. 9, further, in order to prevent damage of the vanes 25, the second ring part 27 is provided to be arranged in the intermediate part of the vanes 25 from the side of the base part 21 toward the first ring part 26, thereby to annularly connect the vanes 25.
This second ring part 27 connects the intermediate parts of the plurality of vanes 25.
Concretely, in order to increase the height of the impeller 20, the vanes 25 extend in the height direction of the impeller 20. The vanes 25 are likely to be damaged in the middle in the height direction of the impeller 20, because the vanes 25 are mutually connected by the first ring part 26 on the side opposite the base part 21.
Therefore, the second ring part 27 is provided within the range of ⅓ on the middle of the height H [mm] of the impeller 20 (within the range from the position of H/6 mm toward the side of the intake port 11 a to H/6 mm toward the side of the base part 21, with the center in the height direction of the impeller 20 regarded as the base).
In other words, when the impeller 20 is divided into three regions, i.e. each respective to ⅓ in the direction (height direction) of the rotary shaft 33 and the three regions are regarded as the first region, the second region and the third region in this order from the side of the base part 21, the second ring part 27 is provided in the second region.
For example, in the resin molding using the mold, it is sometimes difficult to integrally mold the impeller 20 due to problems regarding removal of the mold if the above second ring part 27 is provided. In this case, a preliminary component with the vanes 25 and the second ring part 27 integrally molded is manufactured. Subsequently, the base part 21 and the first ring part 26 manufactured beforehand as the separate components are integrated with the preliminary component by ultrasonic fusing, bonding, etc.
As described above, the second ring part 27 is provided in the intermediate part of the vanes 25 from the side of the base part 21 to the first ring part 26 to annularly connect the vanes 25, so as to prevent deflection of the vanes 25 in this intermediate part and thus to prevent the vanes 25 from being damaged.
This second ring part 27 is likely to be a factor that inhibits the flow of the gas when the gas is taken into the housing 10.
Then, in the present embodiment, as shown in FIG. 9, a connection part 27 a of the second ring part 27 is arranged between the plurality of vanes 25.
The thickness of the connection part 27 a of the second ring part 27 for connecting the vanes 25 is smaller inside in the radial direction than the thickness outside in the radial direction, thereby to prevent the flow of the gas toward the housing 10 from being inhibited.
Concretely, the face 27 aa of the connection part 27 a oriented to the side of the intake port 11 a is a gradient face that nears the side of the base part 21 toward the inside in the radial direction.
Further, the face 27 ab of the connection part 27 a oriented to the side of the base part 21 is a gradient face that nears the side of the intake port 11 a toward the inside in the radial direction.
Therefore, the section of the connection part 27 a assumes the shape of a steeple that tapers toward the inside in the radial direction, so that no extra resistance is generated against the flowing gas.
In the present embodiment, the center line 27 c (see FIG. 9) passing through the center of the section of the connection part 27 a is approximately orthogonal to the rotary axis direction Z (see FIG. 6).
However, only either of the face 27 aa oriented to the side of the intake port 11 a of the connection part 27 a or the face 27 ab oriented to the side of the base part 21 of the connection part 27 a may be used as the above gradient face, and the remaining face may be used as a non-gradient face (a plane approximately orthogonal to the rotary axis direction Z). In this case, the section of the connection part 27 a assumes the shape of the triangle approximate to the right-angled triangle that tapers toward the inside in the radial direction. Even if the section of the connection part 27 a is triangular as described above, it is possible to prevent generation of extra resistance against the flowing gas.
Namely, in the radial direction, the thickness of the outer end portion of the connection part 27 a for connecting the vanes 25 is large, and therefore the second ring part 27 has the connection strength. Further, the thickness of the connection part 27 a is formed to become gradually smaller from the outer end portion to the inner end portion of the connection part 27 a in the radial direction. Therefore, extra resistance is prevented from being generated against the flowing gas.
Further, in the present embodiment, the size (e.g. the diameter) of the outer periphery of the second ring part 27 in the radial direction is approximately equal to the size (e.g. the diameter) of the outer periphery of the vane 25. While not limited to this size, for the reason as stated below, the size may be set to be smaller than the size (e.g. the diameter) of the outer periphery of the vanes 25.
In other words, the outer peripheral part of the second ring part 27 in the radial direction may be at the same position or on the inner side with respect to the outer end portions of the vanes 25.
As used herein, the outer periphery of the vanes 25 means a circumference obtained by connecting the outer end portions of the plurality of vanes 25.
Similarly, the inner periphery of the vanes 25 means a circumference obtained by connecting the inner end portions of the plurality of vanes 25.
The reason therefor will be concretely explained with reference to FIG. 10.
FIG. 10 is a top view showing the centrifugal fan 1 seen from the side of the intake port 11 a.
In FIG. 10 as well, the arrow T indicates the rotary direction of the impeller 20, as shown in FIGS. 6 and 7.
As shown in FIG. 10, the gas (such as air) from the side of the intake port 11 a is taken into the housing 10 by the vanes 25, as shown by the dot arrow, flows in the housing 10 toward the side of the vent 13, and discharges from the vent 13.
In the region X shown in FIG. 10, when there is a gap between the impeller 20 and the housing 10, a part of the gas (such as air) flowing toward the side of the vent 13 flows back into the inside of the housing 10 again.
If such flow is allowed, the force to output the gas (such as air) from the vent 13 is weakened and therefore the airflow-static pressure characteristic is lowered.
Thus, in this region X, it is preferable that the vanes 25 are arranged as near to the housing 10 as possible, thereby to reduce the gap between the vanes 25 and the housing 10.
However, if the diameter of the outer periphery of the second ring part 27 is larger than the diameter of the outer diameter of the respective vanes 25, the impeller 20 needs to be positioned in such a manner that the second ring part 27 does not contact the housing 10, and, disadvantageously, the gap between the vanes 25 and the housing 10 becomes correspondingly larger.
Therefore, the diameter of the outer periphery of the second ring part 27 may be configured to be approximately equal to or smaller than the diameter of the outer periphery of the vanes 25, so that the vanes 25 can be arranged as near to the housing 10 as possible.
Namely, the outer peripheral part of the second ring part 27 in the radial direction may be at the same position as the outer end portions of the vanes 25 or inside these outer end portions, lest the outer peripheral part of the second ring part 27 be arranged outside the outer end portions of the vanes 25.
Meanwhile, when the second ring part 27 protrudes further inside than the inner periphery that connects the radial inner sides of the vanes 25, namely, protrudes into the internal space enclosed by the vanes 25, the flow of the gas flowing through this internal space from the side of the intake port 11 a to the side of the base part 21 is sometimes inhibited.
Therefore, the diameter of the inner periphery of the second ring part 27 in the radial direction may be approximately equal to or larger than the diameter of the inner periphery of the vanes 25. In this case, the inner end portion of the second ring part 27 in the radial direction does not protrude into the internal space enclosed by the vanes 25.
As shown in FIG. 9, the diameter of the outer periphery of the vanes 25 is approximately equal to the outer diameter W [mm] of the impeller 20 and is from about 30 mm to 110 mm. The diameter D [mm] (identical on the sides of the intake port 11 a and the base part 21) of the inner periphery for connecting the insides of the vanes 25 in the radial direction has the relationship of W×0.9 [mm]≧D [mm]≧W×0.4 [mm], where W [mm] is the outer diameter of the impeller 20, so that the gas can be successfully taken up to the side of the base part 21.
FIG. 11 is a sectional view, as FIG. 9, for explaining a variation of the impeller 20.
As shown in FIG. 11, at the connection part 27 a constituting the second ring part 27, the diameter Y2 of the inner periphery (also referred to as the inner periphery of the second ring part 27 in the radial inside) for connecting the radial insides is larger than the diameter Y1 of the outer periphery of the base part 21.
Further, at the connection part 27 a constituting the second ring part 27, the diameter Y3 of the outer periphery (also referred to as the outer periphery of the radial exterior of the second ring part 27) is smaller than the diameter Y4 of the inner periphery for connecting the radial interior of the first ring part 26.
By realizing the above configuration, the impeller 20 is molded to have a structure where resin is injected into the space inside the mold to form the impeller 20 in such a manner that the two molds on the sides of the intake port 11 a (the upper side in FIG. 11) and the base part 21 (the lower side in FIG. 11) are coupled, and thereafter the molds can be removed from the molded impeller 20. Therefore, the base part 21, the vanes 25, the first ring part 26 and the second ring part 27 can be integrally molded by means of injection molding, etc.
In this case, though the connection part 27 a alone does not assume the shape of a ring, the connection part 27 a including the parts of the vanes 25 connected by the connection part 27 a assumes the shape of a ring. Therefore, it should be interpreted that the second ring part 27 in the present invention has the part that is configured to be ringed with the second ring part 27 alone, and also configured to include the parts of the vanes 25 and to annularly connect the vanes 25 including the parts of the vanes 25. The same applies to the first ring part 26.
The features of the centrifugal fan in the second embodiment are summarized as follows.
(1) A centrifugal fan of the present invention comprises a rotary shaft and an impeller, the impeller comprising a base part, vanes provided above the base part in the rotary direction, a first ring part for connecting the end portions of the vanes arranged opposite the base part, and a second ring part for connecting the intermediate parts of the vanes between the base part and the first ring part, wherein the second ring part has the connection parts between vanes, where the thickness of the connection parts on the inside in the radial direction is smaller than the thickness of the connection parts on the outside.
(2) In the above configuration (1), the impeller has the ratio H/W of equal to or larger than 0.55, where H [mm] is a height of the impeller and W [mm] is an outer diameter of the impeller.
(3) In the above configuration (1) or (2), the second ring part has the connection parts whose thickness become smaller from the outside to the inside in the radial direction.
(4) In any one of the above configurations (1) to (3), the outer peripheral part of the second ring part in the radial direction is at the same position or on the inside with respect to the end portions of the vanes on the outside.
(5) In any one of the above configurations (1) to (4), the impeller is equally divided into three regions, each respective to ⅓ in the rotary axis direction and when the three regions are regarded as the first region, the second region and the third region in this order from the side of the base part, the second ring part is provided in the second region.
When increasing the height of the vent of the centrifugal fan, the length of the vanes in the height direction of the impeller can be increased by increasing the height of the impeller. In this case, the vanes are subject to damage in some cases due to centrifugal force and wind pressure. The centrifugal fan of the second embodiment has first and second rings capable of avoiding vane damage.
The present invention has been explained based on the embodiments. The present invention is not limited to the above embodiments and can be varied as long as it does not deviate from the gist of the present invention, which is evident to the skilled person from the attached claims.

Claims

What is claimed is:

1. A centrifugal fan, comprising:

a housing including an intake port; and

an impeller arranged inside the housing, including a base part and a plurality of vanes, wherein

the intake port takes in gas on one end portion side in the rotary axis direction,

a face of the base part on a side of the intake port comprises a gradient face inclined toward a rotary shaft and the intake port,

the plurality of vanes are provided at the gradient face, and

the width of the vanes in the radial direction is increased from the intake port side toward the gradient face.

2. The centrifugal fan according to claim 1, wherein

the ratio H/W is equal to or larger than 0.55, wherein

H [mm] is a length of the impeller in the rotary axis direction and,

W [mm] is a length of the impeller in the radial direction.

3. The centrifugal fan according to claim 1, wherein

the length of the impeller in the radial direction is from 30 mm to 110 mm.

4. The centrifugal fan according to claim 1, wherein

D2 is equal to or smaller than D1×0.9, wherein

D1 [mm] is a distance of the inner shape of the inside of the plurality of vanes on the intake port side and,

D2 [mm] is a distance of the inner shape of the inside of the plurality of vanes on the base part side.

5. The centrifugal fan according to claim 4, wherein

the distance D2 [mm] is equal to or larger than the distance D1×0.4 [mm].

6. The centrifugal fan according to claim 1, wherein

the height of the top portion of the gradient face is smaller than a height of the center of the impeller.

7. The centrifugal fan according to claim 1, wherein

the vanes have an identical curvature radius in the rotary axis direction and

the inner end portion of the vane extends consecutively from the intake port side to the base part side in the radial direction.

8. The centrifugal fan according to claim 1, wherein

the impeller has a ring part coupling end portions of the plurality of vanes on the intake port side and

the outer peripheral part of the base part is inside the inner peripheral part of the ring part in the radial direction.

9. The centrifugal fan according to claim 1, wherein

the outer peripheral part of the plurality of vanes extends in the rotary axis direction.

10. The centrifugal fan according to claim 1, comprising

a motor including a rotary shaft coupled with the impeller, wherein

the base part comprises a first face on the intake port side and a second face on an opposite side to the first face, and

the second face is a gradient face.