JP2000060059A - Rotating electric machine - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce vibration of a rotating electric machine and reduce noise due to the vibration. In AA, a high-rigidity portion includes a terminal box base (5).
Vibration modes other than a multiple of 5 can be suppressed at the five locations of the attachment portions E1, E2, G1, G2 of the leg 6 and the reinforcing ribs 9a and 9d. In BB, the high-rigidity portions are arcs H1, H2, I
Vibration modes other than a multiple of 2 can be suppressed at four places, i. In CC, six reinforcing ribs 9a, 9b, 9c, 9d, 9e, 9f are arranged, and vibration modes other than a multiple of 3 can be suppressed. Therefore, vibrations other than the vibration mode of 30 having the least common multiple of 2, 3, and 5 can be suppressed, and the displacement due to the vibration can be extremely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating electric machine, and more particularly to reduction of electromagnetic vibration and noise.

[0002]

2. Description of the Related Art The magnetomotive force distribution of a stator winding of a rotating electric machine has a distribution in which a spatial harmonic is superimposed on a sine wave (fundamental wave), and this distribution varies with time in proportion to the stator current. In addition, since the openings of the windings and the teeth of the iron core are alternately provided at substantially equal intervals on the inner diameter side of the stator, the magnetic permeance distribution of the stator also has ripples whose periods are slots of the stator. Therefore, the magnetic flux density that the stator creates in the air gap is
Since the product is the product of the stator magnetomotive force distribution and the stator magnetic permeance, the magnetic flux density has a spatial harmonic component.

When the rotating electric machine is an induction motor, rotor bars are arranged on the rotor core at substantially equal intervals. The rotor bar is electrically shorted by an end ring at the axial end of the rotor.

In the rotor bar, a rotating magnetic field generated by the stator and an induced current generated by the rotating motion of the rotor are generated. The magnetomotive force distribution created by this induced current is a distribution in which harmonic components are superimposed on a sine wave. Therefore, the magnetic flux density created by the rotor in the air gap also has ripples, and the magnetic flux density itself rotates, so that the magnetic flux density varies with time.

The magnetic flux density in the air gap is a composite of the magnetic flux density generated by the stator and the magnetic flux density generated by the rotor. And fluctuates over time.

Since the magnetic flux density has a harmonic component in the air gap, the electromagnetic force acting on the stator also generates a harmonic component.

Also, when the rotor is a permanent magnet rotor having a permanent magnet, the permanent magnet also generates a harmonic component in the same manner as the induced current of the rotor bar generates a magnetomotive force having a harmonic component. Forming a rotating magnetic field. Therefore, when the permanent magnet rotor rotates, electromagnetic pulsation in the radial direction occurs.

The main cause of the electromagnetic noise of the motor is the annular vibration of the stator. The radial electromagnetic force acting on the stator causes annular vibration of the stator, and the annular vibration of the stator propagates to the stator frame on the outer peripheral side of the stator, and the stator frame vibrates to produce sound. In particular, when the spatial order and frequency of the electromagnetic force harmonic component in the radial direction match the resonance mode and resonance frequency of the stator, the stator resonates and generates large noise. In the resonance mode having a low spatial order, the vibration displacement increases, and the noise increases.

Japanese Patent Application Laid-Open No. 9-322469 describes that weights are attached to the bottom and side walls of a stator frame main body to reduce the vibration of the stator frame.

Japanese Patent Application Laid-Open No. 7-203657 discloses that in order to maintain the strength of the stator frame, the stator has a projection whose circumferential position is changed for each of a plurality of blocks divided in the axial direction. Is described.

In Japanese Patent Application Laid-Open No. 5-304742, a spring rod is intensively disposed at a portion of a stator core which is a node of an annular vibration mode, and a core support plate is also a node of an annular vibration mode. It is described that an arc-shaped notch is provided in a portion to prevent magnetic vibration of the stator core from being transmitted to the stator frame.

[0012]

In the prior art in which a weight is attached to the stator frame, the weight of the motor itself increases,
In addition, the number of steps for attaching the weight increases.

In the prior art having a protrusion for each stator block, the protrusions are provided intermittently in the axial direction.
In a medium-sized and large-sized rotating electric machine, when receiving a reaction force of torque during rotation, the protrusion of the stator core does not have sufficient strength against a tangential force of the stator. Therefore, although the vibration is reduced, the function of the protrusion to improve the mechanical strength of the rotating electric machine is small. Even in the prior art in which the spring rod is provided on the stator core, the strength of the spring rod itself is small, so that the function of the spring rod to improve the mechanical strength of the rotating electric machine is small.

An object of the present invention is to reduce vibration of a rotating electric machine and reduce noise due to the vibration.

[0015]

A feature of the present invention to achieve the above object is that a high rigid member in the axial direction and a high rigid member in the circumferential direction are provided on the outer peripheral side of the stator frame of the rotating electric machine. The number of high-rigidity members is different depending on the axial direction.

In the stator frame, vibration occurs only in a vibration mode corresponding to the number of axially high-rigidity members. In other words,
Vibration other than the vibration mode corresponding to the number of axially rigid members does not occur. According to the feature of the present invention, since the number of axially high-rigidity members is different in the axial direction, the mode of vibration generated in the stator frame is different in the axial direction, that is, the vibration mode in which the vibration is suppressed in the axial direction is different. . Furthermore, vibrations in vibration modes other than the least common multiple of each vibration mode corresponding to the number of axially high rigidity members in the axial direction are also suppressed. As compared with the case where the number of axially high-rigidity members in the axial direction is fixed, the stator frame as a whole has more vibration modes in which vibration is suppressed, and thus the vibration of the stator frame is further reduced. Therefore,
Vibration of the rotating electric machine can be reduced, and noise due to the vibration can be reduced.

Further, a terminal box pedestal, a hanger or a leg may be provided on the axially high rigidity member or the circumferential high rigidity member.
The terminal box pedestal, the hanger or the leg may also serve as the axially high rigidity member or the circumferential high rigidity member.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a rotating electric machine having a stator and a stator frame, the smaller the order of the resonance mode of the stator, the smaller the order.
Vibration displacement increases.

In order to provide strength to the tangential force of the stator, an axially continuous stator support is provided on the outer peripheral surface of the stator core to support the stator on the stator frame. Via the stator support, the annular vibration of the stator is uniformly transmitted to the stator frame. When the stator frame coincides with the resonance mode, large vibrations are generated and noise is increased. Since the stator support is provided, no measures can be taken to avoid resonance on the outer peripheral surface of the stator core. Therefore, it is necessary to take measures to avoid resonance in the stator frame.

The vibration mode of the stator frame will be described. FIG. 5 is a schematic diagram of the vibration mode. FIG. 5A shows a stator frame 1.
(Vibration mode m = 2). The right drawing of FIG. 5A shows the circumference of the stator frame developed on a straight line. There are two wavelengths on the circumference. Therefore, the number of vibration nodes 18 is four. Similarly, FIGS. 5B and 5C are schematic diagrams of the vibration modes m = 3 and m = 4. The number of nodes of the vibration nodes is 6, 8 in each of the vibration modes m = 3 and m = 4. That is, assuming that the number of vibration nodes is k with respect to the vibration mode number m, the following relational expression holds.

K = 2m Equation (1) In addition, when the driving power supply frequency changes at the time of starting or stopping the variable speed rotating electric machine or the constant speed rotating electric machine, a vibration mode having a different shape appears at a certain resonance frequency. Therefore, a structure of the stator frame that suppresses a plurality of vibration modes is required.

Next, the relationship between the vibration mode of the stator frame and the high-rigidity member will be described with reference to FIGS. FIG. 6 is a schematic diagram of the vibration when the vibration mode m = 2 when the high rigidity members 17 are provided at four locations on the stator frame 1. When an external force such as an electromagnetic force propagates to the stator frame, the high-rigidity member becomes a node of vibration. Therefore, when the number of high rigid members of the stator is k, the number of vibration modes n (integer) is a natural number 1 and is expressed by the following equation.

N = (1/2) k Equation (2) Accordingly, if the vibration mode m = 2, if the number of the high rigid members is four in the circumferential direction on the stator frame, the vibration When the number of nodes is a multiple of four, the high-rigidity member 17 becomes a node of the vibration, so that the vibration cannot be suppressed. Therefore, the number of the high rigidity members 17 is set to six as shown in FIG. From equation (2), the number n of vibration modes whose amplitude increases becomes a multiple of three. Vibration modes that are not a multiple of 3 such as vibration mode m = 2 or vibration mode m = 4 can be suppressed.

However, as shown in FIG. 8, when the vibration mode is a multiple of 3, one or more vibration waves can be generated in the circumferential direction of the high-rigidity member, so that the vibration in the vibration mode is suppressed. Can not do. Here, FIG. 8 is a schematic perspective view of the vibration mode. In general, if k uniform high-rigidity members are provided in the axial direction, the vibration of the vibration mode n represented by the equation (2) cannot be suppressed.

Therefore, means for solving the above problem is shown in FIGS.
This will be described with reference to FIG. FIG. 9 is a schematic diagram of a stator frame. This is an example in which the arrangement and the number of high-rigidity members are changed depending on the axial direction. FIG. 10 is a sectional view taken along the line PP in FIG. Since the number of the high-rigidity members 17 is five in the cross section PP, there is an effect that vibration can be suppressed except in a vibration mode that is a multiple of five. Here, both ends of the high rigidity member 17e are connected to the circumferential reinforcing rib 19a and the bracket 2a in order to increase rigidity. Similarly, at least one other end of the other high-rigidity member is connected to the high-rigidity member of the circumferential reinforcing rib or the bracket.

FIG. 11 shows a cross section QQ. Since the number of high rigidity members is six in the cross section QQ, vibrations other than the vibration mode which is a multiple of three can be suppressed. FIG. 12 shows a cross section RR. Since the number of the high-rigidity members is four in the cross section RR, vibrations other than the vibration mode which is a multiple of 2 can be suppressed. In this case, vibrations other than 2 or 3 or a multiple of 5 can be suppressed. That is, vibrations other than a multiple of 30, which is the least common multiple of 2, 3, and 5, can be suppressed. Since the vibration amplitude is inversely proportional to the fourth power of the number of vibration modes, the vibration mode having a multiple of 30 has a very small vibration amplitude.

Therefore, the number of high-rigidity members is k1, k
2,..., Kj, n1,
Vibrations in vibration modes other than the least common multiple of n2,..., nj can be suppressed. Here, j is the number obtained by dividing the stator frame in the axial direction by the circumferential reinforcing member. As a means for increasing the rigidity, there is a means for increasing the thickness of the stator frame of the terminal box pedestal and legs of the power supply, the suspenders and the reinforcing ribs. Or
In order for the stator to withstand sufficient torque reaction force, the stator can be fitted to the stator frame, or the stator can be fixed using a stator support material approximately the same length as the stator stacking thickness. Connect to stator frame.

(Embodiment) FIG. 1 shows an external view of a rotating electric machine according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line AA of FIG. Brackets 2a and 2b are provided before and after the stator frame 1. The lower part of the stator frame 1 is provided with legs 6. A terminal box 4 is provided above the stator frame 1 via a terminal box base 5. A hanging tool 8 having a hanging tool hole 10 is attached to a side surface of the stator frame 1. Further stator frame 1
A reinforcing rib 9 is provided along the axial direction. Both ends of the reinforcing rib 9 are connected to either the bracket 2 or the hanger 8 or the leg 6. In the present embodiment, the suspension, the terminal box pedestal, and the legs also serve as high rigidity members.

In FIG. 2, there is a shaft 3 at the center,
The rotor 13 is connected to the shaft. Air gap 1
2 there is a stator 11. The stator 11 is connected and supported to the stator frame 1 by a fitting structure. In the AA cross section, the portions having high rigidity are the terminal box pedestal 5 and the mounting portions of the legs 6, E1, E2 and G1, G2, and the reinforcing ribs 9a and 9d. The vibration mode can be suppressed.

FIG. 3 shows a cross section taken along line BB of FIG. The hanging tool 8 having the hanging tool holes 10a and 10b is connected to the stator frame 1 by arcs H1 and H2 and I1 and I2. Accordingly, in the BB cross section of the stator frame, the high rigidity portions are arcs H1 and H
2 and I1, I2 and reinforcing ribs 9c and 9f.
Vibration modes other than a multiple of 2 can be suppressed.

FIG. 4 shows a cross section taken along line CC of FIG. Six reinforcing ribs 9a, 9b, 9c, 9d, 9e, 9 are provided on the stator frame 1.
This is a structure in which f is arranged. Therefore, vibration modes other than a multiple of 3 can be suppressed.

In this embodiment, the arrangement and the number of the high-rigidity sections of the electric motor are different depending on the axial direction. Therefore, in the present embodiment, since vibrations other than the vibration mode of 30 which is the least common multiple of 2 and 3, 5 can be suppressed, there is an effect that displacement due to vibration can be extremely reduced.

In this embodiment, since the hanging member, the terminal box pedestal, and the legs also serve as high rigidity members, the number of reinforcing ribs can be reduced.

The arrangement and number of the high-rigidity members may be changed depending on the axial direction of the stator frame.

[0035]

According to the present invention, vibration modes in which vibration is suppressed in the axial direction are different, and vibration modes other than the least common multiple of each vibration mode corresponding to the number of axially high rigid members in the axial direction are different. Is also suppressed, so that the number of vibration modes in which the vibration is suppressed increases in the whole stator frame, and the vibration of the stator frame is further reduced. Therefore, vibration of the rotating electric machine can be reduced, and noise due to the vibration can be reduced.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a rotating electric machine according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view taken along the line CC of FIG. 1;

FIG. 5 is a schematic diagram of a vibration mode.

FIG. 6 is a diagram illustrating a vibration mode m when four high-rigidity members 17 are provided.
FIG. 4 is a schematic diagram of vibration when = 2.

FIG. 7 is a schematic view of a stator frame in a case where six high-rigidity members 17 are provided.

FIG. 8 shows a vibration mode m when the number of the high-rigidity members 17 is six.
FIG. 4 is a schematic perspective view of vibration when = 3.

FIG. 9 is a schematic diagram of a stator frame.

FIG. 10 is a sectional view taken along line PP of FIG. 9;

FIG. 11 is a sectional view taken along line QQ in FIG. 9;

FIG. 12 is a sectional view taken along line RR of FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stator frame, 2 ... Front bracket, 3 ... Shaft, 4 ...
Terminal box, 5: Base for terminal box, 6: Leg, 7: Fan cover, 8: Hanging tool, 9: Reinforcing rib, 10: Hanging tool hole, 11
... stator, 12 ... air gap, 13 ... rotor, 14 ...
Stator support, 15: pedestal for hanging tool, 16: leg side plate, 1
7: High rigidity member, 18: Vibration node, 19: circumferential rib.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shiobata ▲ Hiro ▼ Nori Kachimachi, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (72) Inventor Motoya Ito 7-1-1, Omikamachi, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Kaoru Kawabata 7-1, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Hiroyuki Mikami 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Research Laboratory F-term (reference) 5H002 AA04 AA08 AB04 5H605 AA04 AA05 BB01 BB05 BB10 CC01 CC02 CC03 CC06 DD39 EC11 FF01

Claims (2)

[Claims] 1. A rotating electric machine having a stator frame that supports a stator from outside, wherein the stator frame has an axially high-rigidity member that is long in the axial direction of the rotating electric machine, and a circumference that extends in a circumferential direction of the rotating electric machine. A rotating electrical machine comprising: a high-rigidity member on the outer peripheral side of the stator frame; and the number of the high-rigidity members in the axial direction varies depending on the axial direction. 2. The rotating electric machine according to claim 1, wherein a terminal box pedestal, a hanger or a leg is provided on the axially high rigidity member or the circumferential high rigidity member.