JP2011179420A - Blower device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blower device which suppresses noise by adjusting the natural frequency of legs to prevent the same from having a value approximate to the frequency of vibration of a motor. <P>SOLUTION: The blower device includes fan blades 5 extending in a centrifugal direction from the outer peripheral face of a hub having the outer peripheral face of a cylindrical shape, a drive part supporting and driving the fan blades 5, and a fan frame 2a supporting the drive part and having an inlet opening 4. The fan frame 2a includes the legs 9a-9c connecting the inner peripheral end on a drive part side of the inlet opening 4 to the outer peripheral end and slits 10 are formed on the outer peripheral end side of the fan frame 2a for allowing extension of the legs 9a-9c. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a blower device used in a cooling device for a heating element such as a CPU mounted inside a housing of an electronic device, for example.

  As a conventional air blower, there is one as shown in (Patent Document 1), and the diameter of the air inlet provided in the fan frame depends on the relationship between the air volume flowing into the fan case from the air inlet and the static pressure. It was limited to a certain range. That is, when used for cooling the heat generating component, it is necessary to provide a large diameter of the intake port in order to secure the air volume required for cooling the heat generating component. However, if the intake port is too large, the static pressure becomes low, and it cannot be mounted on a device with a high mounting density or a device with a narrow dew. Therefore, the diameter of the air intake is limited to a certain range that achieves both airflow and static pressure. Therefore, the length of the foot connecting the fan frame and the motor is also linked to the diameter of the air intake. It was provided with the same diameter.

JP 2001-057493 A

  However, if the length of the diameter of the foot that connects the motor unit that drives the fan blade and the fan frame is limited within a certain range, the rigidity of the foot is increased. As a result, the natural frequency of the foot becomes a value close to the frequency of the vibration caused by the magnetic poles depending on the number of rotations of the motor, and the vibration of the motor is resonated and amplified by the fan frame, and the noise problem of equipment that is incorporated as noise due to vibration Was causing.

  Therefore, the present invention has been made in view of the above problems, and a blower capable of preventing noise from being close to a value close to the vibration frequency of the motor by adjusting the natural frequency of the foot, and to suppress noise. The purpose is to provide.

  Accordingly, the present invention has been made to solve the above problems, and a fan blade extending in a centrifugal direction from an outer peripheral surface of a hub portion having a cylindrical outer peripheral surface, and a drive unit for supporting and driving the fan blade, A fan frame that supports the drive unit and has an intake port, and the fan frame connects the drive unit side inner peripheral end of the intake port and an outer peripheral end facing the inner peripheral end. The air blower is characterized in that a notch for extending the foot is provided on the outer peripheral end of the fan frame.

  With the above configuration, the present invention can adjust the natural frequency of the foot by reducing the rigidity by extending the foot and increasing the diameter. As a result, the noise can be suppressed by preventing the value from being close to the vibration frequency of the motor.

The perspective view seen from the fan frame side of the centrifugal fan apparatus in a present Example The perspective view seen from the fan blade side of the centrifugal fan apparatus in a present Example (A) Top view of the fan frame in this embodiment, (b) Cross-sectional view of the fan frame in this embodiment Enlarged view of the connecting portion between the foot and the fan frame in region A of FIG. The figure which showed the relationship between the magnitude | size Wd of the diameter of a foot | foot part and the natural frequency of a foot | foot part in a present Example. The figure which showed the relationship between the rotational speed of a motor at the time of changing the diameter of the foot part in a present Example, and a sound pressure. The figure which showed the relationship between the width | variety Ws of a foot part and the natural frequency of a foot part in a present Example. The figure which showed the relationship between the thickness Wt of the foot part in this Example, and the natural frequency of a foot part (A) A top view of a fan frame provided with a cut parallel to the longitudinal direction of the foot and a cut at a substantially right angle in this embodiment, (b) a plurality of layers around the entire air inlet in this embodiment. Top view of fan frame with cuts

  According to the first aspect of the present invention, a fan blade extending in a centrifugal direction from an outer peripheral surface of a hub portion having a cylindrical outer peripheral surface, a drive unit that supports and drives the fan blade, a drive unit that supports the drive unit, and an intake port The fan frame includes a foot portion that connects the inner peripheral end portion of the intake port on the drive unit side and the outer peripheral end portion facing the inner peripheral end portion, on the outer peripheral end side of the fan frame. The blower is characterized by a notch that extends the foot part, and by extending the foot part and increasing the diameter, the rigidity can be lowered and the natural frequency of the foot part can be adjusted. The noise can be suppressed by preventing the frequency from being close to the vibration frequency of the motor.

  The invention described in claim 2 is the air blower device according to claim 1, wherein the diameter of the air inlet is 34 mm to 36 mm, and prevents the value from being close to the vibration frequency of the motor. Becomes easier and noise can be further suppressed.

  The invention described in claim 3 is the air blower device according to claim 2, wherein the foot portion has a diameter of 40 mm to 44 mm, and can appropriately adjust the natural frequency of the foot portion. The noise can be suppressed more effectively by preventing the frequency from being close to the vibration frequency of the motor.

Embodiments of the present invention will be described below with reference to the drawings.
(Example)
In the present embodiment, a case where the blower of the present invention is used for cooling a heating fixture will be described.

  FIG. 1 is a perspective view of a centrifugal fan device according to the present embodiment as viewed from the fan frame side. The fan case 2 of the centrifugal fan device 1 includes a fan frame 2a located at the lower part and a fan cover (not shown) located at the upper part. Here, the bottom surface and the side surface of the fan frame 2a are integrally formed by resin molding or aluminum alloy die casting. An exhaust port 3 for exhausting the intake air is disposed on one side surface, and an intake port 4 is disposed on the bottom surface. The fan cover is formed into a plate shape by stamping or resin molding of a metal material such as aluminum or stainless steel, and a substantially circular intake port 4 for sucking air is disposed at the center thereof. .

  And the fan blade 5 is arrange | positioned so that it may be pinched | interposed and accommodated between the fan frame 2a and a fan cover.

  FIG. 2 is a perspective view of the centrifugal fan device according to this embodiment as viewed from the fan blade side. In FIG. 2, the fan blade 5 includes a hub portion 6 having a cylindrical outer peripheral surface and a plurality of blade portions 7 extending radially from the outer peripheral surface in the centrifugal direction. The motor part is provided inside the hub part 6.

  The fan blade 5 is rotationally driven by the motor unit, and the surface shape in the rotation axis direction in a predetermined region of the surface (positive pressure surface) in the rotation direction of the blade unit 7 is such that both end portions in the vertical direction of the blade unit 7 are The blade portion 7 has a shape located on the rotational direction side with respect to the central portion. Further, an upper annular plate 8 that is continuously connected to the upper end portion in the rotation axis direction is provided on the outer peripheral portion of the blade portion 7.

  When the fan blade 5 rotates at a high speed, from the air inlet 4 disposed in the center of the fan cover so as to face the upper surface of the hub portion 6 and the air inlet 4 disposed on the bottom surface of the fan frame 2a. Air is inhaled. At that time, the air is sucked in from the direction of the rotation axis (not shown) of the fan blade 5 to be described later, and the sucked air is further rotated in the fan case 2 by the rotational movement of the blade portions 7. The direction of the wind is changed. Therefore, most of the sucked air collides with the inner walls of the frame 2a and the cover 2b, and the air is sent along the inner walls in the same direction as the rotation direction of the fan blades 5 to be exhausted from the exhaust port 3. The

  Next, the fan frame 2a that is a feature of the present invention will be described in detail.

  FIG. 3A is a top view of the fan frame in the present embodiment, and FIG. 3B is a cross-sectional view of the fan frame in the present embodiment. FIG. 4 is an enlarged view of a connecting portion between the foot and the fan frame in the region A of FIG.

  The foot portions 9 a, 9 b, and 9 c are the end portions of the air inlet 4 and face the connection hole 11, and the inner drive end side inner peripheral end portion 14 on the connection hole 11 side that connects the motor portion and the fan frame 2 a. The outer end 13 of the air inlet 4 is connected. The fan frame 2 a supports a motor unit that supports the fan blade 5. By providing the fan frame 2 a with a notch 10 that extends the foot portions 9 a to 9 c, the diameter Wd of the foot portions 9 a to 9 c is made larger than the diameter of the outer end portion 13 of the air inlet 4. The fan frame 2a is connected to the motor unit through the connection hole 11, and is connected to the fan cover through a plurality of connection units 12 provided.

  Moreover, as shown to Fig.3 (a), it is preferable to provide the leg parts 9a-9c so that the connection part 12 may not be arrange | positioned on the extension line | wire of the longitudinal direction of the leg parts 9a-9c. That is, the vibration of the motor part is transmitted through the foot parts 9a to 9c along the longitudinal direction of the foot parts 9a to 9c. It gets bigger. Therefore, by arranging the connecting portion 12 other than on the extension line in the longitudinal direction of the foot portions 9a to 9c as in the present embodiment, it is possible to further suppress an increase in noise due to motor vibration.

  Further, the shape of the notch 10 is parallel to the longitudinal direction of the legs 9a to 9c as shown in FIG. 4, thereby simplifying the mold for molding and facilitating manufacture, but is not necessarily parallel in this way. There is no need. That is, by making the length of the foot portions 9 a to 9 c longer than the distance between the drive portion side inner peripheral end portion 14 and the outer peripheral end portion 13 of the intake port 4 by the notch 10, the rigidity of the foot portions 9 a to 9 c is achieved. As long as the natural frequency of the feet 9a to 9c can be adjusted. For example, you may form so that the notch 10 may spread toward the outer side like the figure in the vicinity of the part connected with the fan frame 2a. With this configuration, the connection between the foot portions 9a to 9c and the fan frame 2a can be made strong without affecting the fixed frequency of the foot portions 9a to 9c. Therefore, the angle α of the notch 10 at the connecting portion between the foot portions 9a to 9c and the fan frame 2a is preferably about 0 to 60 degrees, and the width d is about 1 mm to 5 mm in this embodiment. When the angle α of the notch 10 is as small as about 0 to 30 degrees (in this embodiment, the width d is about 1 mm), the area of the intake port 4 hardly changes and the static pressure hardly changes. Even a high device or a device having a narrow flow path can inhale at a high static pressure that does not affect the device. Further, when the angle α of the notch 10 is as large as approximately 30 to 60 degrees (in this embodiment, the width d is approximately 5 mm), generation of cavity noise can be suppressed. Cavity noise is noise that occurs when wind passes over a narrow groove, causing the wind to vortex in the groove.

  In the present embodiment, the diameter of the outer end portion 13 of the air inlet 4 is 35 mm, but the diameter of the air inlet 4 is not limited to 35 mm because it depends on the size of the fan blade 5. For example, as a cooling device for an electric device of a notebook PC, the diameter of the outer end portion 13 of the intake port 4 is generally 30 mm to 46 mm, or a cooling device of other sizes may be used. In FIG. 3, Wd represents the diameter of a circle connecting the ends of the feet 9a to 9c where the feet 9a to 9c are connected to the fan frame 2a, Ws is the width of the feet 9a to 9c, and Wt is the foot. The thickness of the parts 9a-9c is shown.

  Next, the relationship between the natural frequency of the feet 9a to 9c and the vibration frequency of the motor unit will be described. The motor unit includes a rotor and a stator. The rotor is provided with a blade portion 7 of the fan blade 5 and a rotor magnet provided with a plurality of magnetic poles on the inner periphery. The stator is provided with a metal electronic steel sheet, in which a winding is wound around an insulator and insert-molded so as to be inserted into the insulator. In order to rotate the rotor, the stator is turned on / off according to the magnetic poles of the rotor magnet, thereby generating vertical vibrations in the thrust direction of the rotor (direction parallel to the rotation axis of the rotor) due to magnetic force fluctuations.

  Therefore, the fundamental frequency of the vibration frequency of the motor is expressed as the number of rotations of the motor multiplied by the magnetic pole of the rotor magnet. When the frequency that is an integral multiple of the fundamental frequency and the natural frequency of the legs 9a to 9c are close to each other, the vibration of the motor is resonated and amplified by the fan frame 2a, and noise due to the vibration increases. Normally, resonance and amplification are not a problem in the fundamental frequency band, and resonance and amplification become the largest when the frequency of 2 to 3 times the fundamental frequency and the natural frequency of the legs 9a to 9c are close to each other. End up. Therefore, it is important to set the natural frequency of the feet 9a to 9c to a value away from a frequency that is two to three times the fundamental frequency.

  In general, when the motor rotates at, for example, 2000 to 6000 r / min, the fundamental frequency of the vibration frequency of the motor is 133 to 400 Hz. As described above, in this band, the vibration of the motor is resonated and amplified by the fan frame 2a, and noise due to the vibration is rarely a problem. In this case, it is necessary to keep the natural frequency of the legs 9a to 9c away from 500 to 1200 Hz, which is 2 to 3 times the fundamental frequency.

  Next, the relationship between the diameter Wd of the legs 9a to 9c and the natural frequency will be described. FIG. 5 is a diagram showing the relationship between the diameter Wd of the foot and the natural frequency of the foot in this example. In addition, the graph a in FIG. 5 is the case where the foot portions 9a to 9c have a width of 3 mm and a thickness of 1.2 mm. In this embodiment, the material of the foot portions 9a to 9c is a resin such as PBT. Graph b shows a case where the width of the foot portions 9a to 9c is 3 mm and the thickness is 0.4 mm. In the embodiment, the material of the foot portions 9a to 9c is an iron material such as SECC, for example.

  When the length of the foot portions 9a to 9c is increased, the rigidity of the foot portions 9a to 9c is generally lowered, and the natural frequency is lowered. Moreover, when the length of the foot portions 9a to 9c is shortened, the rigidity of the foot portions 9a to 9c is generally increased, and the natural frequency is increased. This is because the natural frequency is proportional to the square root of rigidity (spring constant). That is, for example, the wavelength of vibration transmitted from the motor unit to the feet 9a to 9c is determined by the length of the feet 9a to 9c, and the longer the feet 9a to 9c, the longer the wavelength. Since the speed does not change, the natural frequency is lowered.

  Therefore, as shown in FIG. 5, the natural frequency of the feet 9a to 9c decreases as the diameter Wd of the feet 9a to 9c increases.

  As described above, the diameters of the legs 9a to 9c are provided with the notches 10 to extend the length, thereby preventing the vibration of the motor part from being resonated and amplified by the fan frame 2a and becoming noise due to the vibration.

  FIG. 6 is a diagram showing the relationship between the rotational speed of the motor and the sound pressure when the diameter of the foot in this embodiment is changed. In the graph shown in FIG. 6, the widths Ws of the legs 9a to 9c are 1 mm, the thickness Wt is 1.2 mm, and the diameter of the intake port 4 is 35 mm.

  A graph “a” in FIG. 6 is a state in which the diameter of the legs 9 a to 9 c is 35 mm equal to the diameter of the air inlet 4 and the notch 10 is not provided. In this case, compared with the graphs b to e when the notches 10 are provided and the legs 9a to 9c are lengthened, the vibration of the motor is clearly resonated and amplified by the fan frame 2a, and the noise due to the vibration is increased. I understand that.

  The graph b shows that the diameter of the legs 9a to 9c is 40 mm, which is 5 mm larger than the diameter of the air inlet 4, and it can be seen that the vibration of the motor is stable without much resonance and amplification in the fan frame 2a. Graph c shows that the diameter of legs 9a to 9c is 44 mm, which is 9 mm larger than the diameter of intake port 4, and motor vibration is stable without much resonance and amplification in fan frame 2a as in graph b. Recognize. Graph d is 46 mm in which the diameter of feet 9 a to 9 c is 11 mm larger than the diameter of inlet 4, and the noise is smaller than in graph a, but the motor revolves and amplifies slightly at a rotational speed of about 4300 r / min. I understand that At other rotational speeds, the vibration of the motor is stable without much resonance and amplification in the fan frame 2a. Further, in the graph e, the diameter of the feet 9a to 9c is 48 mm, which is 13 mm larger than the diameter of the intake port 4, and the noise is smaller than the graph a as in the graph d, but the motor rotation speed is about 4400 r / min. It can be seen that resonance and amplification occur. At other rotational speeds, the vibration of the motor is stable without much resonance and amplification in the fan frame 2a. Further, as a whole, it can be seen that the sound pressure is small when the diameter of the foot portions 9a to 9c is 40 mm or 44 mm at any rotational speed of the motor. This result is the same not only when the diameter of the intake port 4 is 35 mm but also when it is 34 to 36 mm, and the sound pressure is small when the diameter of the legs 9 a to 9 c is 40 mm or 44 mm. Further, when the diameter of the intake port 4 is 34 to 36 mm, it is easy to prevent a value close to the vibration frequency of the motor, and noise can be further suppressed.

  Further, the natural frequency of the legs 9a to 9c does not depend only on the length of the diameter Wd but also depends on the width Ws and the thickness Wt.

  FIG. 7 is a diagram showing the relationship between the foot width Ws and the natural frequency of the foot in this example, and this graph shows that the thickness Wt of the feet 9a to 9c is 1.2 mm, the diameter Wd is 35 mm, Each case of 40 mm and 46 mm is shown. FIG. 8 is a diagram showing the relationship between the foot thickness Wt and the natural frequency of the foot in this example. This graph shows the foot portions 9a to 9c having a diameter Wd of 40 mm and a width Ws of 3 mm. Show the case.

  As can be seen from FIG. 7, the natural frequency of the foot portions 9a to 9c becomes smaller as the width Ws of the foot portions 9a to 9c is smaller. This is because the smaller the width Ws of the foot portions 9a to 9c, the smaller the rigidity of the foot portions 9a to 9c. Further, as can be seen from FIG. 8, the natural frequency of the feet 9a to 9c becomes smaller as the thickness Wt of the feet 9a to 9c is smaller. This is because the smaller the thickness Wt of the foot portions 9a to 9c, the smaller the rigidity of the foot portions 9a to 9c.

  Next, another form of the foot portions 9a to 9c and the cut 10 will be described. FIG. 9A is a top view of a fan frame provided with a notch parallel to the longitudinal direction of the foot portion and a notch substantially perpendicular to this embodiment, and FIG. 9B shows the intake air in this embodiment. It is a top view of the fan frame which provided the notch | incision so that it might become multiple layers around the circumference | surroundings of an opening | mouth.

  As shown in FIG. 9 (a), by providing the notch 10 parallel to the longitudinal direction of the foot portions 9a to 9c and the notch 10 substantially perpendicular to the foot portion 9a to 9c, the motor portion is transmitted in the longitudinal direction of the foot portions 9a to 9c. By changing the direction of the vibration in a substantially right angle direction, it is possible to make it difficult to be transmitted to the outside of the fan frame 2 a and the connection portion 12. As a result, noise caused by vibration of the motor portion of the fan frame 2a can be reduced. Moreover, since the form of FIG. 9A is very easy to mold like the form of FIG. 3A described above, the manufacture is simplified. Further, as shown in FIG. 9B, by providing the notches 10 so as to form a plurality of layers around the entire periphery of the intake port 4, vibrations transmitted from the motor unit in the longitudinal direction of the feet 9 a to 9 c are absorbed. By changing the direction toward the entire periphery, it is possible to make it difficult to be transmitted to the outside of the fan frame 2a and the connection portion 12. As a result, noise caused by vibration of the motor portion of the fan frame 2a can be reduced. Moreover, it is preferable to provide so that the connection part 12 may not be arrange | positioned on the extension line | wire of the longitudinal direction of the leg parts 9a-9c, regardless of what form.

  As described above, the length of the diameter Wd of the foot portions 9a to 9c is made longer than the diameter of the outer end portion 13 of the intake port 4 by making the notch 10 in the connecting portion between the foot portions 9a to 9b and the fan frame 2a. It can comprise, can reduce rigidity and can reduce the natural frequency of the leg parts 9a-9c. By adopting such a configuration, it is possible to prevent the natural frequency of the legs 9a to 9c from becoming close to a value that is an integral multiple of the fundamental frequency of the vibration of the motor, and the vibration of the motor is resonated and amplified by the fan frame 2a. It is possible to prevent noise from vibration.

  According to the blower of the present invention, the rigidity of the foot can be reduced by increasing the diameter of the foot, and the natural frequency of the foot can be made lower than the vibration frequency of the motor to suppress noise. It is useful as a blower for cooling an electronic device such as a PC.

DESCRIPTION OF SYMBOLS 1 Centrifugal fan apparatus 2 Fan case 2a Fan frame 3 Exhaust port 4 Intake port 5 Fan blade 6 Hub part 7 Blade part 8 Ring plate 9a, 9b, 9c Foot part 10 Cut

Claims (3)

A fan blade extending in the centrifugal direction from the outer peripheral surface of the hub portion having a cylindrical outer peripheral surface;
A drive unit for supporting and driving the fan blade;
A fan frame that supports the drive unit and has an air inlet;
The fan frame includes a foot portion that connects the drive portion side inner peripheral end portion of the intake port and an outer peripheral end portion facing the inner peripheral end portion,
A blower characterized in that a notch for extending the foot portion is formed on the outer peripheral end portion side of the fan frame. The blower according to claim 1, wherein the diameter of the air inlet is 34 mm to 36 mm. The blower according to claim 2, wherein the foot has a diameter of 40 mm to 44 mm.

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