JP2014015908A - Blower unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blower unit capable of reducing electromagnetic noise with a simple constitution without a need of an additional member for sound insulation.SOLUTION: A blower unit 1 comprises: a fan to which multiple blades are fixed; a motor 7 to the motor shaft of which the fan is mounted, and that is housed in a motor case; and a blower case 2 in which the fan and the motor are built, and that forms an air passage and forms an outer shape. At a motor bottom on an opposite output side of the motor shaft, the motor case is fixed immediately to the blower case 2 by plural screws 6. The plural screws 6 are arranged on an almost circumference from a motor center. A portion of the blower case 2 surrounded by plural screw fixing sections is constituted by a rib 30 comprising a rib extending from the motor center in a circumferential direction and radial ribs extending in a radial direction. The rib 30 is pressure-welded to a motor lower section, and restrains resonance of the motor 7 and the blower case 2 by a spring property of the rib 30.

Description

  The present invention relates to a blower unit in which a motor and a fan are integrated and housed in a case.

  In a motor used for a vehicle-mounted blower unit or the like, the rotor is rotated by appropriately switching the magnetic force between the stator and the rotor. When this magnetic force is switched, magnetic vibration is generated in the rotation direction of the motor, and electromagnetic noise is generated due to the magnetic vibration. The frequency of the electromagnetic noise of the motor is determined by the alternating frequency of the magnetic force, that is, the frequency of the AC voltage applied to the motor. When electromagnetic noise is generated in the motor, the electromagnetic noise is amplified by resonance between the motor and the blower case that houses the motor, and may become noise having a large peak at a specific frequency fm as shown in FIG. In FIG. 8, when the level of electromagnetic noise at resonance exceeds the level of background noise, electromagnetic noise becomes a big problem.

  Then, the structure which attaches a stator part to an outer case via vibration-proof rubber, prevents that a vibration transmits to an outer box by vibration-proof rubber, and reduces electromagnetic noise (resonance sound) is proposed ( For example, see Patent Document 1).

JP 2005-299432 A

  However, in the configuration proposed in Patent Document 1, an additional member for soundproofing such as a vibration proof rubber is required, which is a factor that hinders downsizing and cost reduction of the blower unit.

  The present invention solves the above-described problems, and an object of the present invention is to provide a blower unit that does not require an additional member for soundproofing and can reduce electromagnetic noise with a simple configuration.

  In order to achieve the above object, a blower unit of the present invention includes a fan having a large number of blades fixed thereto, a motor mounted on a motor shaft and housed in a motor case, a fan and a motor built in, and an air In the blower unit comprising a blower case that forms a passage and an outer shape, the motor case is fixed directly to the blower case with a plurality of screws at the bottom of the motor on the side opposite to the output side of the motor shaft. The screw is arranged approximately on the circumference from the motor center, and the portion surrounded by the plurality of screw fixing portions of the blower case extends in the radial direction with an annular rib extending in the circumferential direction from the motor center portion. It is composed of radial ribs, and the ribs are pressed against the lower part of the motor, and the resonance between the motor and the blower case is suppressed by the spring property of the ribs.

  With such a configuration, the spring is provided in the blower case at the bottom of the motor so that the motor is pressed in the electromagnetic vibration direction and resonance between the blower case and the motor is suppressed. For this reason, an additional member for soundproofing is not required, and electromagnetic noise of the blower unit can be reduced with a simple configuration.

  According to the present invention, it is possible to provide a blower unit capable of reducing electromagnetic noise with a simple configuration without requiring an additional member for soundproofing.

The perspective view of the blower unit in embodiment of this invention Cross-sectional view of XZ plane seen from direction A of the blower unit Sectional view of XY plane seen from B direction of the blower knit Perspective view of the blower case of the blower unit Bottom view of the blower case of the same blower unit Two-dimensional vibration characteristics diagram of the motor bottom of the blower unit The figure which shows the noise measurement result of the blower unit Illustration for explaining electromagnetic noise of motor

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the effects of the present invention are not limited to the following examples.

(Embodiment)
The structure of the blower unit 1 in this Embodiment is demonstrated with reference to FIGS. 1 is a perspective view of a blower unit according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the blower unit taken along the XZ plane viewed from the A direction, and FIG. 3 is an X- view viewed from the B direction of the blower unit. It is sectional drawing of a Y surface. In the present embodiment, an in-vehicle blower unit for cooling a battery will be described as an example.

  The blower unit 1 has a blower case 2 made of resin, a motor 7 and a fan 3 housed in the blower case 2. The blower case 2 is configured by connecting a blower upper case 2 a and a blower lower case 2 b with a hook 8. On the output side of the motor shaft 22 of the motor 7, a fan 3 for blowing air to which a large number of blades 14 are fixed is connected. The blower case 2 forms an air passage 10 on the outer periphery of the fan 3 and forms the outer shape of the blower unit 1. The motor case 15 (case lid 15 b) is directly fixed to the lower blower case 2 b by three screws 6 at the motor bottom portion on the opposite side of the motor shaft 22. A plurality of ribs 30 having spring properties are formed in pressure contact with the motor 7 on the motor bottom side of the blower lower case 2b, and the motor 7 is urged upward by the ribs 30 (Y direction). The blower lower case 2b is provided with a fixed mounting foot 5 for mounting the blower unit 1 to a mounting base (not shown).

  The blower unit 1 includes an intake port 9 (FIG. 3) that opens upward (Y-axis direction) in the direction of the motor shaft 22. Further, the blower unit 1 includes a jet port 4 that opens in a direction orthogonal to the motor shaft 22 (X-axis direction). When the motor 7 rotates, the fan 3 rotates through the motor shaft 22 and sucks outside air from the air inlet 9, and the sucked outside air is blown out from the outlet 4 through the air passage 10 to cool the battery.

  Next, the internal structure of the blower unit 1 will be described in detail with reference to FIG. In the present embodiment, an example of an inner rotor type brushless motor in which a rotor is rotatably disposed on the inner peripheral side of a stator will be described.

  As shown in FIG. 3, the motor 7 includes a stator 11, a rotor 12, a circuit board 13, and a motor case 15. The motor case 15 is made of metal and includes a case main body 15a having an opening on the motor bottom side and a case lid 15b that closes the opening. A stator 11, a rotor 12, and a circuit board 13 are accommodated in the motor case 15. In the present embodiment, the side on which the case lid 15b is arranged is described as the bottom side, and the opposite side is described as the upper side or the head side.

  A rotor 12 is inserted on the inner peripheral side of the stator 11 through a gap. The rotor 12 holds a cylindrical permanent magnet 20 on the outer periphery of the rotor frame 19 and is disposed so as to be rotatable around a motor shaft 22 supported by a bearing 21. The bearing 21 is fixed to the case body 15a. Further, one end portion of the motor shaft 22 is rotatably supported by a thrust plate 23 disposed at the center portion of the case lid 15b. The motor shaft 22 passes through the top surface of the bearing 21 and the case main body 15a, and the other end of the motor shaft 22 projects to the head side as an output shaft. It is attached. A rotor frame 19 is fixed to the motor shaft 22. The permanent magnet 20 fixed to the outer peripheral side of the rotor frame 19 is disposed so as to face the tip surface of the salient pole of the stator core 17. The permanent magnet 20 is magnetized at equal intervals in the circumferential direction so that S poles and N poles are alternately arranged.

  Further, the circuit board 13 built in the motor case 15 is mounted with a drive control circuit for controlling the motor 7 and for energizing and driving the winding 18.

  By supplying a power supply voltage and a control signal from the outside to the motor 7 configured as described above, a drive current flows through the winding 18 by the control circuit and the drive circuit of the circuit board 13, and a predetermined value is output from the stator core 17. An alternating magnetic field with a frequency is generated. The alternating magnetic field from the stator core 17 and the magnetic field from the permanent magnet 20 generate an attractive force and a repulsive force according to the polarities of the magnetic fields, and the rotor 12 rotates around the motor shaft 22 by these forces. The fan 3 connected to the motor shaft 22 rotates in conjunction with the rotation of the rotor 12. At this time, electromagnetic vibration corresponding to the alternating frequency of the alternating magnetic field is generated. Then, the electromagnetic noise vibration of the motor may be amplified by resonating with the natural vibration of the structural system of the motor case 15 or the blower case 2, resulting in a large electromagnetic noise. The magnitude of the electromagnetic noise is affected by the material and structure of the motor case 15 and the blower case 2 or the mounting structure of the motor case 15 and the blower case 2.

  A large number of blades 14 are formed along the outer periphery of the fan 3. The case main body 15a and the case lid 15b are fixed by a blower lower case 2b and screws 6 in the vicinity of the outer periphery thereof. An air passage 10 is formed on the outer periphery of the fan 3 of the blower unit 1 configured as described above, and external air sucked from the intake port 9 is ejected from the ejection port 4 via the air passage 10. The

Next, a detailed configuration of the blower case 2 will be described with reference to FIGS. 4 and 5.
FIG. 4 is a perspective view of a blower case of the blower unit in the embodiment of the present invention, and FIG. 5 is a bottom view of the blower case.

  As shown in FIGS. 4 and 5, a rib 30 is formed on the bottom side of the lower blower case 2b. The rib 30 includes annular ribs 30a and 30k and a plurality of radial ribs 30b to 30j. The rib 30a extends in the circumferential direction from the central portion of the motor 7 and is formed in an annular shape. The rib 30k extends in the circumferential direction, and is formed in a concentric ring shape on the outer side of the rib 30a. The ribs 30b to 30j extend in the radial direction so as to connect the annular ribs 30a and the ribs 30k, and are formed radially at substantially equal intervals. A region 32 surrounded by the inner periphery of the rib 30a and a region 33 surrounded by the rib 30a, the rib 30k, and the ribs 30b to 30j are hollow, and thus the rib 30 has a spring property. The rib 30 is formed so as to be surrounded by three screw fixing portions 31a to 31c. These ribs 30a to 30k are in pressure contact with the bottom of the motor 7, and the resonance between the motor 7 and the blower case 2 is suppressed by the spring property of the ribs 30a to 30k. Note that the shape of the ribs 30 and the number of screw fixing portions 31 are not limited to those in the present embodiment, and may be any structure that has a spring property and suppresses resonance between the motor 7 and the blower case 2.

  Next, the effect of providing the spring-like rib 30 on the bottom side of the blower lower case 2b will be described in comparison with a conventional blower lower case. When an alternating current whose polarity alternates at a predetermined frequency flows through the winding 18 of the stator 11, an alternating magnetic field is generated in the stator core 17 as described above. The alternating magnetic field acts on the magnetic field from the permanent magnet 20 of the rotor 12 to rotate the rotor 12, and electromagnetic vibration corresponding to the frequency of the alternating magnetic field is generated. This electromagnetic vibration resonates with the natural vibration of the structural system such as the motor case 15 and the blower case 2 to generate electromagnetic noise.

  FIG. 6 is a two-dimensional vibration characteristic diagram of the bottom of the motor 7. In FIG. 6, the deformation amount (μm) of vibration of 4.872 KHz in the height direction, that is, the direction of the motor shaft 22 (Y direction) is shown as contour lines. As shown in FIG. 6, the motor 7 is a two-dimensional vibration in which vertical vibrations (Y-axis vibration) are generated alternately on the left and right sides about the axis A (X-axis direction) passing through the bottom center of the motor 7. Has vibration mode. That is, in the two-dimensional vibration mode as shown in FIG. 6, when the left side of the motor 7 is moving in the T direction (head direction), the right side of the motor 7 is moving in the B direction (bottom direction), When the left side moves in the B direction, the right side vibrates so as to move in the T direction.

FIG. 7 is a diagram illustrating frequency characteristics of electromagnetic noise of the blower unit according to the present embodiment. In FIG. 7, the horizontal axis represents frequency (KHz), and the vertical axis represents sound pressure level (dB). The upper characteristic graph shows the case where the conventional blower lower case is used, and the lower characteristic graph shows the case where the blower lower case 2b of the present embodiment is used. The characteristic graph on the left shows the case where the air volume is 52 m ³ / h and the static pressure is 34.2 Pa (case A), and the characteristic graph on the right shows the case where the air volume is 60 m ³ / h and the static pressure is 45.6 Pa (case B). ). The numerical values in each characteristic graph are the average sound pressure level in the upper row, the peak frequency and the sound pressure level at that time in the lower row. Here, the conventional blower lower case has the same shape as the blower lower case 2b of the present embodiment, and does not have the rib 30 at the bottom.

  As shown in FIG. 7, in case A, when a conventional lower blower case is used, the peak frequency of electromagnetic noise is 4.84 KHz and the noise level is 3.78 dB. On the other hand, when the lower blower case 2b of the present embodiment is used, the peak frequency of electromagnetic noise is 4.95 KHz and the noise level is -1.07 dB. That is, when the lower blower case 2b of the present embodiment is used, the noise level at the peak frequency is improved by 4.85 db as compared with the case where the conventional lower blower case is used.

  Similarly, in case B, when a conventional lower blower case is used, the peak frequency of electromagnetic noise is 4.85 KHz and the noise level is 3.74 dB. On the other hand, when the lower blower case 2b of the present embodiment is used, the peak frequency of electromagnetic noise is 4.95 KHz and the noise level is -2.87 dB. That is, when the lower blower case 2b of the present embodiment is used, the noise level at the peak frequency is improved by 6.61 dB compared to the case where the conventional lower blower case is used.

  This is because the lower case 2b of the present embodiment in the two-dimensional vibration mode shown in FIG. 6 has a spring-like rib 30 formed on the bottom side of the motor 7 so that it is in the B direction. One side that vibrates at a time is always pressed in the head direction (Y direction). Thereby, the deformation amount by the electromagnetic vibration of the motor 7 is reduced, and the resonance between the motor 7 and the blower case 2 is suppressed. As a result, electromagnetic noise caused by electromagnetic vibration is reduced. Further, the degree of improvement of electromagnetic noise by the rib 30 varies depending on the material of the blower case 2 and the shape of the rib 30.

  As described above, according to the blower unit of the present invention, the spring bottom rib provided on the bottom side of the blower case is pressed against the motor bottom, so that the motor bottom is pressed in the electromagnetic vibration direction and the blower case and the motor Resonance is suppressed. For this reason, an additional member for soundproofing is not required, and electromagnetic noise of the blower unit can be reduced with a simple configuration.

  The present invention can be widely used to suppress noise having a peak at a specific frequency in a device that resonates with the vibration of the motor and the structural system other than the above-described on-vehicle cooling blower.

DESCRIPTION OF SYMBOLS 1 Blower unit 2 Blower case 2a Blower upper case 2b Blower lower case 3 Fan 4 Spout 5 Fixed mounting foot 6, 6a-6c Screw 7 Motor 8 Hook 9 Air inlet 10 Air passage 11 Stator 12 Rotor 13 Circuit board 14 Blade 15 Motor Case 15a Case body 15b Case lid 17 Stator core 18 Winding 19 Rotor frame 20 Permanent magnet 21 Bearing 22 Motor shaft 23 Thrust plate 30, 30a-30k Rib 31, 31a-31c Screw fixing part 32, 33 region

Claims (4)

A fan with a large number of blades fixed,
A motor mounted on a motor shaft and housed in a motor case;
In the blower unit comprising the fan and the motor, and a blower case that forms an air passage and forms an outer shape,
The motor case is fixed directly to the blower case with a plurality of screws at the bottom of the motor on the side opposite to the output side of the motor shaft, and the plurality of screws are disposed substantially on the circumference from the motor center. A portion of the case surrounded by the plurality of screw fixing portions is configured by an annular rib extending in the circumferential direction from the motor central portion and a radial rib extending in the radial direction, and the rib is formed by the motor. A blower unit, wherein the blower unit is pressed against a lower portion and suppresses resonance between the motor and the blower case by the spring property of the rib. The blower unit according to claim 1, wherein the blower case includes a blower upper case and a blower lower case, and the rib is formed in the blower lower case. The blower unit according to claim 1 or 2, wherein the motor case is made of metal, and the blower case is made of resin. The blower unit according to claim 1, wherein the motor is an inner rotor type brushless motor.

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