This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2011-063107, filed on Mar. 22, 2011, the entire contents of which are incorporated herein by reference.
The embodiment discussed herein is directed to an axial blower.
An axial blower is used for cooling electronic equipments in many cases. An amount of heat generated by parts incorporated in an electronic equipment tends to increase, and it is necessary to improve a cooling effect of an axial blower. In order to improve a cooling effect, it is suggested to increase a revolution speed of the axial blower or stacking a plurality of axial blowers in an axial direction to increase a fan pressure or velocity pressure.
It is known that an operation sound generated by an axial blower, when the axial blower is operated, increases in proportion to a fifth or sixth power of a revolution speed. Accordingly, if the revolution speed of the axial flower is increased, the operation sound is also increased.
Here, when an electronic equipment is used in an ordinary office or home, there may be a problem that an operation sound of an axial blower incorporated in the electronic equipment causes an undesirable noise. Thus, it is desirable to reduce an operation sound of an axial blower. Therefore, it is suggested to reduce an operation sound by adopting an axial blower of a contra-rotating type and devising shapes of a moving vane and a stationary vane (for example, refer to Japanese Patent Publication No. 4128194).
Generally, an axial blower is designed to be operated at a target operating point which is set in accordance with a system impedance of the equipment into which the axial blower is incorporated. The target operating point is an operating condition acquired as an intersection of the system impedance of the equipment into which the axial blower is incorporated and a static pressure-air flow amount characteristic of the axial blower. When the axial blower is operating at the target operating point, the aerodynamic property of the axial blower is at the highest. Thus, the operation sound is made as small as possible by using an axial blower of which operation sound becomes small when the axial blower is operated at the target operating point.
However, in a case where a system impedance of the equipment slightly varies when the axial blower is incorporated into the equipment, the actual operating point of the axial blower is shifted from the target operating point. As a result, it is possible that the operation sound of the axial blower is increased. Such a shift of the actual operating point can be adjusted by changing a structure of the axial blower to cause the operating point of the axial blower to match the actual system impedance of the equipment. For example, the target operating point can be shifted by changing the shapes of a moving vane and/or a stationary vane.
However, in order to change the shapes of the moving vane and the stationary vane of an axial blower to match a system impedance of an equipment, it is necessary to prepare many moving vanes having different shapes and many casings constituting stationary vane having different shapes so as to perform an adjustment while incorporating axial blowers equipped with moving vanes and stationary vanes having different shapes. Such an operation takes a long time, thereby increasing a cost. Additionally, it is necessary to prepare many molds for molding the moving vanes and the casings to prepare the moving vanes and stationary vanes having different shapes, which may require an extremely large cost.
According to an aspect of the invention, an axial blower includes: a moving vane generating air flow by rotation; a casing accommodating said moving vane; and an adapter detachably attached to the casing, the adapter including a fitting part to be fit to an inner surface of the casing, the adapter forming a protrusion or a step on the inner surface of the casing.
The object and advantages of the embodiment will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary explanatory only and are not restrictive of the invention, as claimed.
Preferred embodiments of the present invention will be explained with reference to the accompanying drawings.
The inventors found that an operation sound generated by an axial blower such as, for example, an axial fan can be reduced by generating turbulence in air flow inside a casing of the axial blower by providing a protrusion or step on an inner surface of the casing.
In
In the axial blower illustrated in
The step or protrusion for generating turbulence can be provided by, for example, molding the casing 2 so that the step or protrusion is formed in the inner surface 2a of the casing 2. However, when the step or protrusion is integrally formed as a part of the casing 2, the entire casing 2 must be replaced with a different casing in order to change a shape of the protrusion or a height (level difference) of the step. Thus, the inventors considered that such an inconvenience can be omitted by providing the protrusion or step by attaching an adapter on the inner surface 2a of the casing 2 while maintaining the inner surface 2a of the casing 2 to be a cylindrical form.
The axial blower 10 illustrated in
In the structure illustrated in
When the fitting part 20a of the adapter 20 is fitted to the inner surface 12a of the casing 12 as illustrated in
The position of the tip of the fitting part 20a is a position where the stopper part 20b bumps into the flange part 10a of the axial blower 10. Thus, by providing the stopper part 20b on one end side of the fitting part 20a, the tip of the fitting part 20a can be positioned with high accuracy in the casing 12. That is, by merely inserting the fitting part 20a into the casing 12 until the stopper part 20b bumps into the flange 10a of the axial blower 10, the tip of the fitting part 20a can be positioned with high accuracy, thereby forming the step at an accurate position on the inner surface 12a of the casing 12.
The height and shape of the step are not limited to that illustrated in
Although the adapter 20 illustrated in
Here, a turning flow of air may be generated in the vicinity of the inner surface 12a of the casing 12 due to rotation of the moving vane 16. In such a case, if the strip parts 20Bf are formed by the slits 20Be extending in the axial direction as is in the adapter 20B illustrated in
It should be noted that, as illustrated in
A description is given below, with reference to
First, a characteristic of an axial blower to be incorporated into an equipment is acquired (step S1), and a system impedance of the equipment (a resistance loss with respect to an air flow in the equipment) is acquired (step S2). Then, an operating point, at which the axial blower is operated when the axial blower is incorporated in the equipment, is acquired, and an operation sound (noise) of the axial blower being operated at the acquired operating point is acquired (step S3). Then, it is determined whether the operation sound acquired in the step S3 is equal to or smaller than an allowable value (step S4). If the operation sound is equal to or smaller than the allowable value, a determination is made that there is no need to improve the operation sound (noise) and the axial blower is made as a completed product without change (step S5). On the other hand, if the operation sound exceeds the allowable value, a determination is made that an improvement in the operating sound (noise) is necessary and the above-mentioned turbulence generating step or protrusion is formed (step S7). In this connection, various adapters for forming the turbulence generating step or protrusion are prepared beforehand (step S6). After attaching one of the adapters to the axial blower, the axial blower is incorporated into the equipment and an operation sound is checked. If the operation sound (noise) is equal to or smaller than the allowable value, the axial blower in which the adapter has been incorporated is made as a completed product (step S5).
According to the above-mentioned procedure of selecting an adapter, adapters having various shapes are prepared beforehand, and an optimum one of the adapters can be found by checking an operation sound while changing the adapters incorporated in the axial blower. At this time, the turbulence generating step or protrusion can be formed easily at an accurate position by merely inserting and attaching the adapters to the casing of the axial blower. Moreover, because the adapters are merely inserted into and fitted to the casing, the adapter can be exchanged easily to the adapter having a different shape, which enables easy selection of an appropriate adapter within a short time.
A description is given of an effect of formation of the above-mentioned turbulence generating step or protrusion on the inner surface of the casing. In the above-mentioned embodiment, the turbulence generating step or protrusion is formed in a single stage axial blower (a single fan) as an axial blower. However, the turbulence generating step may be formed in a contra-rotating type axial blower (contra-rotating type fan) having moving vanes arranged in two stages in an axial direction. For example, turbulence may be generated in the vicinity of the moving vane of the second (rear) stage by forming the turbulence generating step or protrusion at a position between the moving vanes that rotates opposite directions to each other in the contra-rotating type axial blower in order to reduce an operation sound of the contra-rotating type axial blower. Usually, the contra-rotating type axial blower can be divided between a front stage blower and a rear stage blower. In such a case, the adapter may be inserted into the rear stage blower having the rear stage moving vane from a side of a support part. Alternatively, the adapter may be inserted into the rear stage blower having the rear stage moving vane from an open side (a side through which air flows out).
In
On the other hand,
As indicated in
All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed a being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relates to a showing of the superiority and inferiority of the invention. Although the embodiment(s) of the present invention(s) has(have) been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
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2011-063107 | Mar 2011 | JP | national |