JPH08107650A - Rotary electric machine - Google Patents

Abstract

PURPOSE: To change the natural frequency of an entire electric motor by varying the stiffness of a heat exchanger or the wind tunnel for taking in external air for cooling and the mounting part of an electric motor frame. CONSTITUTION: A heat exchanger 17 is clamped to a frame 12 by utilizing a hard rubber 18, a metal spacer 20 which is adjusted to a length where the hard rubber slightly contracts, and a screw hole 22 which is provided at the frame 12 of an electric motor by a bolt 19 via a fixing device 21 of a heat exchanger 17. Two drill holes 24 and 24a are provided in addition to a drill hole 23 for passing the clamping bolt 19 are provided at the fixing device 21 of the heat exchanger 17 and mounting stiffness adjustment bolts 26 and 26a are clamped to the screw holes 25 and 25a which are provided at the heat exchanger. The stiffness when the heat exchanger 187 is displaced to a lower part changes from a high stiffness due to the deformation of metal to a low stiffness supported by a hard rubber 18, thus avoiding resonance state corresponding to the installation state of a shipped destination and achieving a quiet operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of vibration characteristics of a rotary electric machine equipped with a heat exchanger or a wind tunnel.

[0002]

2. Description of the Related Art An electric motor with a heat exchanger shown in FIGS. 8 and 9 will be described as an example. In FIG. 8, 1 is a stator iron core,
Stored in frame 2. A rotor core 3 is fitted to the shaft 4, supported by bearings 5 and 5a, and attached to the frame 2 via bearing brackets 6 and 6a. 7
The heat exchanger is a hard rubber 8 on the frame 2 as shown in FIG.
It is fixed with a bolt 9 through. In particular, the number of bolts for the attachment of the heat exchanger 7 and the frame 2 is determined so that there is no problem in strength, and the bolts of the designed number are always used for fastening.

Since the electric motor generally operates quietly, the unbalance of the rotary shaft 4 is corrected and the exciting force of the rotational frequency component is reduced as much as possible. However, in reality, since a slight imbalance remains, some exciting force of the rotational speed component exists.

On the other hand, when the natural frequency of the entire motor system coincides with the rotation frequency, the vibration response sensitivity increases and the operating vibration of the motor increases. Therefore, a design is performed in which the natural frequency is detuned from the rotation frequency, and the natural frequency is measured on the foundation of the factory at the time of factory shipment to confirm that the natural frequency is detuned before shipment.

[0005]

However, the installation rigidity of the motor to which the product is shipped often differs from the rigidity of the evaluation foundation of the factory. In particular, due to recent trends in weight reduction and size reduction and material cost reduction, the electric motor installation base of the shipping destination has become weak, and the natural frequency of the electric motor installation system tends to decrease. Therefore, even though the natural frequency and the excitation frequency are detuned, the natural frequency matches the excitation frequency of the electric motor and resonates due to the installed state of the electric motor at the shipping destination. May increase the driving vibration of. In such a case, as a means for quietening the operation of the electric motor, it is necessary to reinforce the installation base of the electric motor or the frame 2 of the electric motor to change the natural frequency of the electric motor installation system. However, these reinforcements require a large design change and welding of members, and there is a problem that the change cost and period are lost. Therefore, the resonance phenomenon is easily avoided to reduce the operating vibration of the motor. A method was desired.

The present invention has been made in view of the above circumstances, and provides an electric motor having a structure capable of changing the natural frequency of the entire electric motor system and capable of avoiding a resonance state and performing quiet operation. The purpose is to do.

[0007]

The electric motor of the present invention is characterized in that the rigidity of the attachment portion of the wind tunnel and the electric motor frame for taking in the outside air for heat exchanger or cooling is variable.

[0008]

According to the above structure, the natural frequency of the entire system of the electric conductor can be freely changed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 7 by taking an electric motor with a heat exchanger as an example as in the case of the conventional example. FIG. 1 is a cross-sectional view showing a main part of a joint portion between a heat exchanger and an electric motor frame as seen from a direction perpendicular to a rotating shaft, and FIG. 2 is a cross-sectional view showing a main portion of the same joint portion as seen from an axial direction.
In the figure, 12 is a frame of an electric motor, 17 is a heat exchanger, which is a coupling portion of the heat exchanger 17 fixed to the frame 12 (a circular portion 30 surrounded by a chain line in FIG. 8), a hard rubber 18 and this hard The heat exchanger 17 is fixed by the bolt 19 through the metal spacer 20 whose length is adjusted so that the rubber 18 contracts slightly and the fixing device 21 of the heat exchanger, by using the screw hole 22 provided in the frame 12 of the electric motor. It is tightened. The fixing device 21 of the heat exchanger 17 is provided with a tightening bolt 19
There are two drill holes 24, 24a other than the drill hole 23 through which the screw holes 25, 25a provided in the heat exchanger 17 are provided.
The mounting rigidity adjusting bolts 26, 26a are fastened to the. It should be noted that these coupling portions are provided at several locations on both sides of the heat exchanger 17 symmetrically with respect to the axial length of the shaft 4. (Four corners fixed in principle) According to the above configuration,
The rigidity of the mounting portion when the heat exchanger 17 is displaced downward is
The shrinkage rigidity of the spacer 20, the flexural rigidity of the fixing device 21 of the heat exchanger, and the tensile rigidity of the mounting rigidity adjusting bolts 26, 26a basically have high rigidity due to the deformation of the metal part. Conversely, the mounting rigidity when the heat exchanger 17 is displaced upward is determined by the tensile rigidity of the tightening bolt 19 and the heat exchanger 17
The combination of the flexural rigidity of the fixing device 21 basically has high rigidity due to the deformation of the metal part.

However, the mounting rigidity adjusting bolts 26, 26
By removing a, the rigidity when the heat exchanger 17 is displaced upwards hardly changes. However, the rigidity of the downward displacement changes from a relatively high rigidity state due to the deformation of the metal to a relatively low rigidity state supported by the hard rubber 18. Therefore, the rigidity of the mounting portion is reduced as a whole, and the natural frequency of the entire electric machine system can be changed.

FIG. 3 is a calculation model for evaluating the vibration characteristics of the electric motor with a heat exchanger. The symbols in the figure are: m1: weight of frame including stator core and bearing bracket, m2: heat exchanger Weight, m3: weight of rotor, k1: installation rigidity of electric motor, k2: mounting rigidity of heat exchanger, k3: supporting rigidity of rotor. 4 to 6 show the results of calculation of the natural frequency of the entire electric machine system using this model.

FIG. 4 shows an example at the time of evaluation in a factory. M1 = 4000 [kgf], m2 = 500 [kgf], m3 = 700 [kgf], k1 = 100000 [kgf / mm], k2 = 4500 [kgf] / Mm], k3 = 10000 [kgf / mm], the modes from the 1st to the 3rd are shown, and the frame 12, the heat exchanger 17 and the rotor of the electric motor are regarded as mass points and are displayed graphically. is there.

The second mode diagram of FIG. 4 will be described. The mass point 4-2-1 representing the frame 2 including the stator iron core 1 and the bearing brackets 6 and 6a is designated by the spring having the installation rigidity K1 of the electric motor with respect to the foundation 4-2-0.

The mass point 4-2-1 representing the heat exchanger is connected to the mass point 4-2-1 by a spring having a mounting rigidity K2 of the heat exchanger. The mass point 4-2-3 representing the rotor is connected to the mass point 4-2-1 by a spring having a supporting rigidity K3 of the rotor.

For example, in the case of a two-pole electric motor in which vibration is a particular problem, the vibration frequency component of the rotational imbalance is 50 or 60 [Hz], but the data at the factory evaluation shown in FIG. The number is 45.3 [H in the 1st mode.
z], 2nd, 55.5 [Hz], and 3rd mode, 88 [Hz], which are detuned from the excitation frequencies of 50 and 60 [Hz], respectively.

Next, assuming that this electric motor is installed on the relatively flexible base of the shipping destination, k1 = 5000 [k
gf / mm] (other parameters are the same), and the result of calculating the natural frequency of the entire motor system is shown in FIG. In this state, the natural frequency of the secondary mode is 49.7 [Hz]
In the 50 [Hz] area, a resonance state occurs and driving vibration increases, which is a dangerous state.

FIG. 6 shows a state in which the mounting rigidity adjusting bolts 26, 26a of the heat exchanger described in this embodiment are removed.
k1 = 5000 [kgf / mm], k2 = 2700 [k
gf / mm] (other parameters are the same as the calculation in FIG. 4), and is 49.6 [Hz] in the secondary mode.
Changes to 38.6 [Hz], and resonance can be avoided. Resonance of natural frequencies of other modes does not occur.
With the operation described above, it is possible to provide the electric motor that can avoid the resonance state and perform quiet operation.

In the present embodiment, the electric motor with a heat exchanger is used for explanation, but the present invention can be applied to an electric motor having a wind tunnel for taking in outside air, and is not limited to the electric motor, but is also applicable to general rotating machines such as generators. It can also be applied to electric machines.
Further, in this embodiment, the tightening bolt 1 for mounting the heat exchanger
Although the mounting rigidity adjusting bolts 26 and 26a are arranged for 9 respectively, the mounting rigidity adjusting bolts 26 and 26a are configured to have a large number by only the tightening bolt 19 and the hard rubber 18.
26a and the tightening bolt 19 in combination, and only the tightening bolt 19 is arranged, for example, 1: 2, 1: 3, 1: 4.
Like a small number and a large number of combinations. Alternatively, the former is placed at the four corners of the combination and the latter is placed at the center. Furthermore, the former is in the four corners, and the former and the latter are in the middle: 1: 2, 1:
Make it like 3: 1: 4. Further, in the combination so far, within the range where there is no problem in terms of mounting strength, the bolts of the former and the latter are reduced and, as shown in FIG. 7, in the drill hole 27 on the heat exchanger for inserting the tightening bolt 19, It is also possible to use a method in which the lid 28 made of a metal or a polymer material is provided and the natural frequency of the entire electric motor system is varied.

[0019]

As described above, according to the present invention, the natural frequency of the entire system of the electric conductor can be easily changed, so that the resonance state can be avoided in accordance with the installation state of the shipping destination, and the silence can be suppressed. It is possible to provide an electric motor that can perform various operations.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of a coupling portion between a heat exchanger and a rotating electrical machine frame according to the present invention,

FIG. 2 is a cross-sectional view showing a main part of a coupling portion between a heat exchanger and a rotating electrical machine frame according to the present invention,

FIG. 3 is a diagram showing a vibration characteristic evaluation model of a rotary electric machine with a heat exchanger,

FIG. 4 is a vibration characteristic evaluation result diagram of a rotating electric machine at a factory test,

FIG. 5 is a vibration characteristic evaluation result diagram of a rotating electric machine on a relatively flexible structure base at a shipping destination,

6 is a vibration characteristic evaluation result diagram after adjusting mounting rigidity according to the present invention, FIG.

FIG. 7 is a cross-sectional view showing a state in which a part of the tightening bolt according to the present invention is covered with a lid,

FIG. 8 is a sectional view of a conventional rotary electric machine,

FIG. 9 is a view corresponding to FIG. 1 of a conventional example.

[Explanation of symbols]

2, 12 ... Frame, 4 ... Rotation axis,
7, 17 ... Heat exchanger, 8, 18 ... Hard rubber, 9, 19 ... Tightening bolts, 21
... Fixing device for heat exchanger, 26, 26a ... Mounting rigidity adjusting bolt, 28 ... Lid.

Claims (4)

[Claims] 1. A pipe ventilation type heat exchanger for exchanging heat without mixing the outside air for cooling and the inside air, or a rotating electric machine on which a wind tunnel provided for guiding the outside air for cooling is installed. The electric machine according to claim 1, wherein the heat exchanger or the wind tunnel is combined with a tightening bolt and a mounting rigidity adjusting bolt, and is tightened and fixed to a frame through a fixing device to change the natural frequency of the entire rotating electric machine system. . 2. The combination of the tightening bolt and the mounting rigidity adjusting bolt is a large number in the former and a small number in the latter.
The rotating electric machine as described. 3. The rotary electric machine according to claim 1, wherein the combination of the tightening bolt and the mounting rigidity adjusting bolt is symmetrical in the axial direction of the rotary shaft. 4. The rotating electric machine according to claim 1, wherein the number of the tightening bolts and the mounting rigidity adjusting bolts is variable, and a lid is planted in a space hole without both bolts.