JP2008115790A - Rotating machine - Google Patents

Abstract

The present invention provides a rotating machine that can secure sufficient cooling performance in both forward and reverse rotational directions and can reduce noise generated by a fan.
A fan formed of a disk-shaped hub that also serves as a boss fixed to a rotating shaft and a plurality of blades provided radially on a flat plate surface of the hub is connected to the rotating machine outside the stator frame of the rotating machine. In the rotating machine for forward and reverse bi-directional rotation, which is attached to the shaft end of the rotating shaft and covered with a fan cover, and cooling air is blown to the outer peripheral wall of the stator frame by the fan to cool the rotating machine. The fan blades are slanted in the height direction with the leading edge on the rotating shaft side being blunt, the width is narrowed from the proximal side to the distal side in the height direction and the radial direction, and the radial direction The shape is symmetrical with respect to the center line.
[Selection] Figure 2

Description

  The present invention is applied to a rotating machine in which a fan is attached to a rotating shaft of a rotating machine that rotates forward and reversely, and the fan is cooled by sending air to the outer periphery of a stator frame of the rotating machine. It relates to an improvement to reduce.

  Here, a full-closed outer fan induction motor will be described as an example of a rotating machine for both forward and reverse rotation.

  7 and 8 show a conventional fully-enclosed external fan induction motor as disclosed in Patent Documents 1 and 2. FIG. FIG. 7 is a front view including a partial cross-section thereof, and FIG. 8 is a side view including a partial cross-section viewed from the non-driving side. In these drawings, a rotating shaft 2 that holds a rotor 1 is rotatably supported by both end brackets 5 of a stator frame 4 that holds a stator 3 via bearings 6 and extends to the outside of the stator frame 4. A fan 7 is attached to the opposite end of the rotating shaft 2 on the side opposite to the driving side. The fan 7 has a peripheral wall attached to the stator frame 4 and is covered with a fan cover 9 having an intake port 8 on the side wall. The fan 7 rotates integrally with the rotating shaft 2 and blows the cooling air sucked from the intake port 8 to the outer periphery of the stator frame 4 to cool the rotating machine.

Since the fan 7 is used for both forward and reverse rotations, it constitutes a paddle-type centrifugal fan formed by providing a plurality of flat plate-like blades 11 radially on the flat plate surface of the disk-like hub 10 at a predetermined interval. Further, the air inlet 8 of the fan cover 9 can be constituted by a plurality of concentric fan-shaped openings 8a as shown in FIG. 8 and a plurality of concentric small holes 8b as shown in FIG. .
JP 2000-050574 A JP 2003-180051 A

  The fan in the conventional rotating machine is a paddle type fan in which a plurality of flat blades are vertically provided in a radial direction on a flat surface of a disk-shaped hub. In addition, although the air can be blown at a high pressure, there is a problem that the air blowing efficiency is low and the noise is large.

  This is considered to be due to the following reasons.

  That is, in the case of a paddle type fan, as shown in FIG. 9, the air flowing into the inlet portion inside the blades 11 of the fan 7 has an axial flow velocity, but the blades 11 rotate and rotate in the circumferential direction. Therefore, the combined (relative) flow of air flowing into the wing is a flow having a circumferential flow velocity. For this reason, in the case of a paddle type fan in which the angle of the leading edge of the blade inlet is 90 degrees, the inflowing air flows so as to collide with the wall, and a large backward vortex flow in the rear in the blade rotation direction. It is considered that the development region occurs and the air flow between the blades is disturbed, so that the air blowing efficiency is lowered and the generation of noise is increased.

  Further, when the air inlet 8 of the fan cover 9 is constituted by a plurality of concentric fan-shaped openings 8a as shown in FIG. 8, the air flow deviation generated by the radial grid and the fan blades 11 interfere with each other. In particular, the noise level of the blade passing noise component (number of blades × rotation speed (rps)) increases. For this reason, a fan cover 9 provided with a porous intake port in which small holes 8b are arranged at equal intervals on the circumference of a plurality of concentric circles as shown in FIG. 10 may be used. The reduction effect was not obtained.

  In order to solve such problems in the conventional apparatus, the present invention provides a rotating machine that can secure sufficient cooling performance in both the forward and reverse rotational directions and can reduce noise generated by a fan. Is an issue.

  In order to solve the above-mentioned problems, the present invention provides a fan formed of a disk-shaped hub that also serves as a boss fixed to a rotating shaft and a plurality of blades provided radially on the flat plate surface of the hub. It is attached to the shaft end of the rotating shaft of the rotating machine outside the child frame, covered with a fan cover, and the fan is used to cool the rotating machine by blowing cooling air to the outer peripheral wall of the stator frame. In the rotating machine for rotating in opposite directions, the fan blades are inclined in the height direction with the leading edge on the rotating shaft side being blunt, and the width is increased from the proximal side to the distal side in the height direction and the radial direction. The shape is narrower toward the center and symmetric with respect to the center line in the radial direction (claim 1).

  In the rotating machine according to claim 1, the end surface of the blade in the direction of the rotation axis is a flat surface, and the inner diameter Dj between the blades opposed to the diameter Di of the fan with respect to the diameter Di of the air inlet formed in the fan cover. The ratio (Dj / Di) is preferably 0.8 to 1.0.

  As described above, according to the present invention, the shape of the blade of the fan in the rotary machine is blunted at the front edge on the rotating shaft side of the blade serving as the air inlet, and the blade width is set to the proximal end in the radial direction and the height direction. By making the shape narrower from the side toward the tip side, the air flow at the front edge of the wing becomes smooth and the rear vortex development area can be narrowed, so that the blowing efficiency can be improved and the generation of noise is reduced can do. Further, by making the blades symmetrical with respect to the center line in the radial direction of the hub, the blade can be used for both forward and reverse rotations.

  Embodiments of the present invention will be described below based on examples shown in the drawings.

  1 to 4 show an embodiment of the present invention. FIG. 1 is a front sectional view of an essential part thereof, FIG. 2 is a front view of a fan used in the present invention, and FIG. FIG. 4 is a sectional view taken along line bb of FIG. 2.

  In these drawings, a rotating shaft 2 that holds a rotor 1 is rotatably supported by brackets 5 at both ends of a stator frame 4 that holds a stator 3 via bearings 6, and is disposed outside the stator frame 4. A fan 20 is attached to the opposite end of the extended rotating shaft 2 on the driving side. The fan 20 is covered with a fan cover 9 having an outer peripheral wall attached to the stator frame 4 and a porous air inlet 8 on the side wall. The configuration in which the fan 20 rotates integrally with the rotary shaft 2 and blows the cooling air sucked from the intake port 8 to the outer peripheral wall of the stator frame 4 to cool the rotating machine is the same as that of the conventional apparatus.

  As shown in FIG. 2, the fan 20 includes a disk-shaped hub 21 and a plurality of blades 22 arranged radially on the flat surface of the side surface of the hub 21 at a predetermined pitch. Each wing 22 is configured symmetrically with respect to a radial center line l passing through the center of the hub 21, and the front edges 23 facing each other in the diametrical direction of the hub are blunt like an arc in a plan view. It has a shape (see FIG. 2) and is formed in a conical surface shape inclined at an inclination angle α (see FIG. 3) with respect to the height direction (direction perpendicular to the flat plate surface of the hub 21). The side plates 24 of the blades 22 are similarly inclined in the height direction at an inclination angle β as shown in FIG. 4, and the width in the radial direction of the blades is the blade width angle from the center side to the outer peripheral direction as shown in FIG. The shape is narrowed by θ.

  The inclination angle α of the leading edge 23 of the blade is preferably set to 50 to 70 °, the inclination angle β of the side plate 24 is set to about 10 °, and the blade width angle θ is preferably set to about 10 °.

  As described above, the shape of the blades 22 is such that the front edge 23 of the blades 22 serving as the inlet of the outside air of the fan 20 is blunted and the blade width is narrowed toward the outer periphery. By using a shape with an inclination angle so that the height of the blade becomes thinner in the height direction, it is possible to narrow the rear vortex development region of the wing, thereby reducing the generation of fan noise and the radial center line. By being symmetrical with respect to, it can be used for both forward and reverse rotation.

  The side plate 24 of the wing 22 may not be a flat surface but may be a curved surface that bulges outward so that the radial cross section is a smooth arc with the axis of the rotation shaft as the apex.

  In the fan 20, the end face 25 of the blade 22 (the end face in the axial direction facing the side wall provided with the air inlet 8 of the fan cover 9 when attached to the rotating machine) is used as the side wall face of the fan cover 9. If the planes are parallel, the sealing effect of the gap in the axial direction of the rotation axis between the blade 22 and the fan cover 9 can be enhanced, so that the air on the positive pressure side ahead in the rotation direction of the blade gets over the blade and The amount of wraparound to the rear side, which is a negative pressure, is reduced, and it is possible to suppress the expansion of the rear vortex development region generated behind the blade. For this reason, since the main flow area where the flow of the airflow between the blades is smooth can be widened, it is possible to further reduce the generation of noise.

  Further, the ratio Dj / the distance Dj (refer to FIG. 2) between the diametrically opposed blades at the inlet of the fan 20 in the rotating machine (refer to FIG. 2) and the diameter Di of the air inlet 8 of the fan cover 9 When the blades 22 are arranged on the hub 21 so that Di is 0.8 to 1.0, the air blowing efficiency can be kept high. Strictly speaking, the inter-blade distance Dj is set to the distance between the center points of the arcs of the front edge of the axial end face 25 of the wing 22 facing in the diametrical direction.

  In accordance with the present invention, a test was carried out to measure the level of noise generated when rotating at a constant (3600 rpm) rotation speed for a rotating machine equipped with a fan having a constant outer diameter and various Dj / Di values. The results are shown in FIG. In FIG. 5, the horizontal axis represents Dj / Di, and the vertical axis represents the noise level (dB) corresponding thereto.

As shown in FIG. 5, when the outer diameter of the fan 20 is constant, when Dj / Di is larger than 1.0, the blade length L (see FIG. 3) increases, and there is no decrease in the air flow rate. Since the front edge of the wing is located outside the air inlet 8 of the fan cover 9, the effect of making the front edge blunt is lost, so the noise reduction effect is reduced and the noise level is increased. It can be seen from FIG. 5 that when Dj / Di is smaller than 0.8, the diameter of the inlet portion of the fan is reduced, so that not only the air flow is reduced and the cooling effect is lowered, but also the noise level is increased. The
Therefore, in order to obtain a large noise reduction effect while keeping the fan blowing efficiency high, it is optimal to select the fan Dj / Di value between 0.8 and 1.0.

  Furthermore, FIG. 6 shows the noise when a noise measurement test is performed at a rotational speed of 60 rps on a rotating machine equipped with a fan 20 according to the present invention having six blades and Dj / Di set to 0.9. These frequency characteristics are shown together with those of the conventional apparatus.

  The characteristic line A in FIG. 6 shows the measurement result of the embodiment of the present invention, and the characteristic line B shows the measurement result of the conventional apparatus. When the characteristic lines A and B are compared, the peak value of the noise level at 6 × 60 = 360 Hz, which is a passing noise component of the blades 22 of the fan 20, and 720 Hz, 1080 Hz, which is an integral multiple thereof, is more according to the present invention. It can be seen that the noise level of the wide band of 1 kHz or more generated by random eddy currents is smaller than that by the conventional apparatus, and that the noise reduction effect by the present invention is high. .

  As described above, according to the present invention, in a rotary machine that is cooled by a fan attached to the rotary shaft of the rotary machine, the flow of air in the fan is smoothed to suppress pressure fluctuations, thereby reducing the amount of air blown. In addition, the noise of the fan can be reduced, so that the cooling effect of the rotating machine can be enhanced and the noise can be reduced.

It is a principal part longitudinal cross-sectional view of the fully enclosed fan-shaped rotary electric machine by the Example of this invention. It is a front view of the fan used for an Example in this invention. It is sectional drawing of the aa line | wire of the wing | blade in FIG. It is sectional drawing of the bb line of the wing | blade in FIG. It is a characteristic diagram which shows the relationship of the noise with respect to the value of Dj / Di of the fan of the rotary machine by the Example of this invention. It is a characteristic diagram which shows the frequency characteristic of the noise of the rotary machine by the Example of this invention, and the conventional rotary machine. It is a front view including the partial cross section of the conventional fully enclosed fan-shaped rotary electric machine. It is a side view including the partial cross section of the conventional fully enclosed outside fan-shaped rotary electric machine. It is explanatory drawing of the ventilation operation | movement of the conventional fan. It is a perspective view which shows the fan cover of the other type used for a rotary machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotor 2 Rotating shaft 3 Stator 4 Stator frame 7 Rotating blade 8 Inlet 9 Fan cover 20 Fan 21 Hub 22 Blade 23 Blade front edge 24 Blade side plate 25 Blade end face

Claims (3)

  A fan formed by a disk-shaped hub that also serves as a boss fixed to the rotating shaft and a plurality of blades provided radially on the flat plate surface of the hub is connected to the rotating shaft of the rotating machine outside the stator frame of the rotating machine. In the rotating machine for forward / reverse bidirectional rotation in which the rotating machine is attached to the shaft end and covered with a fan cover, and cooling air is blown to the outer peripheral wall of the stator frame by the fan to cool the rotating machine. The blade is slanted in the height direction with a blunt leading edge on the rotating shaft side, its width narrows in the height direction and the radial direction from the proximal side to the distal side, and becomes a radial center line. A rotating machine characterized by having a symmetrical shape.   2. The rotating machine according to claim 1, wherein an end surface of the blade in the direction of the rotation axis is a flat surface.   3. The rotating machine according to claim 1, wherein a ratio (Dj / Di) of an inner diameter Dj between blades facing each other in a diameter direction of the fan to a diameter Di of an air inlet formed in the fan cover is 0.8 to 1. .. A rotating machine characterized in that it is 0.

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