JPH07288944A - Ventilation-noise preventing structure of induction motor - Google Patents

Abstract

PURPOSE:To prevent a whiz noise from being generated due to a passage noise by a method wherein an air stream which is generated by the fan action of a rotor bar is prevented from passing the end part of a stator coil. CONSTITUTION:A stator core 3 is provided with a rotor bar 4, and an end ring 8 is connected to the end part of the rotor bar 4. A stator slot in a stator core 6 is provided with a stator coil 7, a wedge 20 is mounted on, and attached to, the stator slot, and the stator coil 7 is fixed. The wedge 20 at an end part protrudes from the edge of the stator core 6, the length in the axial direction of a protruding part outside the core is nearly equal to the length of a part which protrudes from the end part of the rotor core 3 out of the rotor bar 4, and the adjacent parts outside the cores are overlapped in the circumferential direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to prevention of ventilation noise of an induction motor and prevents generation of ventilation noise and improves cooling capacity.

[0002]

2. Description of the Related Art FIG. 7 shows a squirrel cage induction motor 1. As shown in the figure, in the squirrel-cage induction motor 1, a rotor core 3 is fixed to a shaft 2, and the rotor core 3 is provided with a rotor bar 4. A stator core 6 is fixed to the frame 5, and the stator core 6 is provided with a stator coil 7.

An end ring 8 is connected to the end portion of the rotor bar 4, as shown in FIG. 8 in which the end portions of the iron cores 3 and 6 are further enlarged and in FIG. 9 which is a sectional view of the rotor as seen from the inner peripheral side. Has been done. Further, a wedge 9 is driven into the slot provided with the stator coil 7, and a spacer 10 for preventing ventilation noise is provided between the stator coils 7 protruding from the end of the iron core.

The wedge 9 is provided in each stator slot to hold the stator coil 7 in the stator slot. The thickness (radial length) of the wedge 9 is 1.6 [mm], and the length per one (axial length) is 100 to 150.
[Mm], and the number of the cores, which is commensurate with the core lamination length (axial core length), is installed in the slots.

The spacers 10 arranged between the stator coils 7 are made of an insulating material, specifically, felt. The spacer 10 is arranged in a section that extends in the axial direction from the end surface of the iron core 6 over a length corresponding to the axial length of the portion of the rotor bar 4 from the end surface of the iron core 3 to the end ring 8. Note that, as shown in FIG. 10, since the mutual spacing of the stator coils 7 is different between the inner diameter side and the outer diameter side,
The spacer 10 installed here needs to be attached with care so that no gap is generated.

In high-speed machines (two-pole machines and four-pole machines) and large-capacity machines, if the spacer 10 is not provided, the wind generated by the fan action of the rotor bar 4 causes ventilation noise at the end of the stator coil 7 ( Wind noise) occurs. Frequency f of the ventilation sound, the number of N ₂ of rotor bars 4, when the rotational speed and rpm, f = a _{(N 2 × rpm) / 60} [H Z]. When the spacer 10 is provided, the wind caused by the fan action of the rotor bar 4 can be prevented from passing through the end portion of the stator coil 7, so that ventilation noise can be prevented.

The conditions for providing the spacer 10 differ depending on the noise specifications, but normally the wind speed of the rotor is 45 [m / sec].
The spacer 10 is installed when the distance exceeds.

[0008]

By the way, in the above prior art, the spacer 1 is provided between the stator coils 7 to prevent ventilation noise.
Since 0 is provided, there is a drawback that the cooling surface area of the stator coil 7 is reduced and the temperature rise is increased.

[0009]

In order to solve the above problems, according to the present invention, a rotor core is provided with a rotor bar, an end ring is connected to the rotor bar, and a stator slot of the stator core is provided. In an induction motor in which a stator coil is provided, and a wedge is attached to a stator slot to fix the stator coil, the wedge at the end of the wedge is projected from the end surface of the stator iron core, and the iron core of the protruding wedge is provided. The axial length of the outer part is approximately equal to the length of the rotor bar from the end face of the stator core to the end ring, and the outer parts of the protruding wedge core are overlapped with each other in the circumferential direction. Characterize.

[0010]

According to the present invention, the wind generated by the fan action of the rotor bar is blocked by the outer portion of the iron core of the wedge and does not pass through the end of the stator coil, so that the generation of ventilation noise can be prevented.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an iron core portion of a squirrel cage induction motor according to an embodiment of the present invention, and FIG. 2 shows the rotor of the embodiment as seen from the inner peripheral side. As shown in both figures, the rotor core 3 is provided with a rotor bar 4, and an end ring 8 is connected to an end portion of the rotor bar 4. On the other hand, a stator coil 7 is provided in a stator slot of the stator core 6, and a wedge 20 is driven into the stator slot to hold the stator coil 7.

Of the wedges, the one to be inserted into the back of the stator slot has the same rectangular shape as the conventional one, but the wedge 20 used at both ends is used.
Is L-shaped as shown in FIG. In the wedges 20 used at both ends, the width (circumferential length) of the inner core portion 20a that enters the stator slot of the stator core 6 is equal to the width of the stator slot, and the outer core protruding from the end surface of the stator core 6 The width W _{out of the} portion 20b is set to be slightly larger than the slot pitch τ _S. Therefore, as shown in FIGS. 4 and 5 (VV cross section in FIG. 4), the adjacent wedges 20 are overlapped at the outer core portion 20b, and the overlap margin K is set to 1 to 3 [mm]. Further, the length (axial length) of the outer core portion 20b of the wedge 20 is made equal to the axial length of the portion of the rotor bar 4 extending from the end surface of the rotor core 3 to the end ring 8.

In this embodiment, when the stator is impregnated with resin, the overlapping portion of the wedge 20 on the outer core portion 20b is firmly bonded by the resin. In this embodiment, the spacer which has been conventionally used is not used.

In the above-described embodiment, the outer core portions 20b of the wedges 20 are overlapped and connected to each other to form a cylindrical member. The cylindrical member formed of the outer core portion 20b has the rotor bar 4 protruding from the end of the rotor core 3,
It will be surrounded from the outer peripheral side. Therefore, the wind generated by the fan action of the rotor bar 4 is blocked by the cylindrical member (outer core portion 20b) and does not pass through the end portion of the stator coil 7, so that a ventilation noise (wind noise) is generated. It can be prevented.

Further, since the spacer is not required, the cooling surface area of the stator coil 7 is increased and the coil temperature is lowered. It was noted that the spacers had to be attached so as not to create a gap (see FIG. 10), but the wedges 20 were simply attached to the conventional work, and the assembly work was simple.

The wedge is not limited to the L-shape but may be a T-shape wedge 21 as shown in FIG. In short, the wedges may have any shape as long as the width of the wedge outside the core is wider than the slot pitch and adjacent to each other.

[0018]

According to the present invention as specifically described in connection with the above embodiments, the outer core portions of the wedges overlap each other in the circumferential direction, and the outer core portions form the rotor bars outside the core. Since it is surrounded from the outer peripheral side, the wind due to the fan action of the rotor bar does not pass through the stator coil end portion, and the generation of ventilation noise is eliminated.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing the rotor of the embodiment as viewed from the inner peripheral side.

FIG. 3 is a configuration diagram showing a wedge of the embodiment.

FIG. 4 is a configuration diagram showing a wedge of the embodiment.

FIG. 5 is a sectional view showing an overlapping state of wedges.

FIG. 6 is a configuration diagram showing another example of a wedge.

FIG. 7 is a configuration diagram showing an induction motor.

FIG. 8 is a configuration diagram showing a conventional technique.

FIG. 9 is a configuration diagram showing a conventional rotor as viewed from the inner peripheral side.

FIG. 10 is a configuration diagram showing a conventional technique.

[Explanation of symbols]

 1 Squirrel cage induction motor 2 Shaft 3 Rotor iron core 4 Rotor bar 5 Frame 6 Stator iron core 7 Stator coil 8 End ring 9 Wedge 10 Spacer 20,21 Wedge 20a Iron core inner part 20b Iron core outer part

Claims (1)

[Claims] 1. A rotor core is provided with a rotor bar, an end ring is connected to the rotor bar, a stator coil is provided in a stator slot of the stator core, and a wedge is attached to the stator slot. In an induction motor with a fixed stator coil, the wedge at the end of the wedge is projected from the end surface of the stator core, and the axial length of the protruding wedge outside the core is the rotor core end surface of the rotor bar. A structure for preventing draft noise of an induction motor, which is approximately equal to the length of the portion from the end ring to the end ring, and the outer portions of the iron core of the protruding wedge overlap each other adjacent to each other in the circumferential direction.