JPS639253Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an AC motor that prevents vibration and noise from occurring during rotation.

Normally, an AC motor as shown in FIG. It is designed and assembled to be. However, due to the accuracy of the parts such as the bracket 4 and the bearings 5 and 6, and variations during assembly, the gap length t also varies to some extent. Then,
Vibration and noise occur under certain conditions.

That is _, assuming that _{the direction} of the tension F _{1 of} the belt ₇ is to _the right in _{FIG . 2}・l ₃ /l ₂ +l ₃ (sinωt) ^2Here , as shown in Figure 2, F ₁ is approximately constant over time, F ₂ is proportional to the square of the magnetic flux, and F ₂ ∝
(sinωt) ² and changes over time. In addition, ω=
2πf, f=power frequency.

In the above configuration, F ₁・(l ₁ +l ₂ +l ₃ )<F ₂・l ₃
Under these conditions, F ₃ becomes positive and negative repeatedly as shown by the dotted line in Figure 2. In other words, when the force F ₂ at the gap length _{t 1 is} biased more toward the opposite side by approximately 180 degrees with respect to the direction of the belt tension F 1, that is, when the force F _{2 at the gap length t 1} is more biased toward the opposite side than the gap length t ₂ in the same direction as the belt tension F 1, If the gap length t ₁ is short t ₁ > t ₂ and F ₁ is positive, then
The waveform changes when F ₂ is on the negative side. Therefore, the rotating shaft 3 vibrates as indicated by the dotted line _F3 in FIG. 2, and the impact with the bearing 5 causes abnormal vibrations and noise.

Therefore, the magnetic attraction force between the stator 2 and the rotor 1 is set in the same direction as the belt, that is, F ₃
By setting ≧0, vibration and noise can be reduced as much as possible.

The present invention was developed in view of the above points, and by narrowing the gap length between the rotor and stator on the side in the same direction as the tension and widening it on the opposite side, at least the bearing that directly receives the tension can be exposed to repeated positive and negative forces. This was done so that it would not be affected.

An embodiment of the present invention will be described below with reference to FIG. Note that the same parts as in FIG. 1 are given the same reference numerals.

Reference numeral 2 denotes a stator, and the stator 2 is fixed with bolts 10, with mounting holes 8 near the outer periphery aligned with mounting holes 9 of the bracket 4. Further, bearings 5 and 6 are provided approximately at the center of the bracket 4.
A rotating shaft 3 integral with the rotor 1 is pivotally supported. A pulley 11 is fixed to the end of the rotating shaft 3, and a tension _F1 is applied to the belt 7 in a certain direction.

In this case, the bearing 5 that directly receives the tension F ₁
The gap length in the same direction as the belt tension F ₁ on the side closer to is t ₂₁ , the opposite side is t ₁₁ , and the other bearing 6
When the gap length in the same direction as the belt tension F ₁ on the side closer to is t ₂₂ and the gap length on the opposite side is t ₁₂ , t ₁₁ > t ₁₂ , t ₁₂
The configuration is such that <t ₂₂ .

As a first concrete method for achieving such a configuration, the mounting position 12 of one bearing 5 of the bracket 4 is shifted from the center in the same direction as the belt tension _F1 , and the mounting position 12 of the other bearing 6 is shifted from the center. 13
is shifted in the opposite direction to the belt tension _F1 to slightly tilt the rotating shaft 3. In this way, the force F ₃ of the bearing 5 is only in the right direction in the figure, and the force F ₄ of the bearing 6 is only in the left direction in the figure.
Regarding 6, vibration and noise are prevented.

The second method is to accurately set the positions of the bearings 5 and 6 and the stator mounting holes 9 and 9 of the bracket 4,
The positions of the mounting holes 8 on the left and right sides of the stator 2 are slightly different, and the gap lengths t ₁ and t ₂ in FIG. 1 are made different on the left and right sides. In other words, contrary to Fig. 1, the gap length t ₂ in the same direction as the belt tension F ₁ is narrowed,
Increase the gap length t ₁ on the opposite side. In the case of this second method, since the force F ₄ and the magnetic attraction force F ₂₂ of the other bearing 6 are in opposite directions, there is no vibration and noise prevention effect on this other bearing 6, but one of the Since the bearing 5 accounts for most of the vibration and noise generation, this alone has a considerable effect.

By the way, in the case of the AC motor of a washing machine, the set gap length t is 0.3 mm, but the deviation is about 10% of that.
It is enough.

Incidentally, the magnetic attraction force is expressed by the following so-called Behrend equation, and it is preferable that the eccentric distance be as small as possible.

Magnetic attraction force = 1/25・S (B/1000) ² Δ/δ Here, S is the gap area, B is the effective value of the magnetic flux density, Δ is the eccentricity size, and δ is the average value of the gap. .

In the embodiment described above, it is preferable that the direction of the belt tension _F1 and the eccentric direction of the bearing 5 substantially coincide with each other, but they may be within a certain range, for example, about 90 degrees. Furthermore, it is effective within a 180 degree range.

As mentioned above, in this invention, the gap between the stator and rotor is made eccentric in the direction of the load, so vibrations and
Noise can be prevented as much as possible. Moreover, unlike conventional methods, there is no need to increase component precision and assembly precision, so it can be provided at an extremely low cost, and when put into practical use, its effects are tremendous.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional AC motor, FIG. 2 is an explanatory diagram of the forces of each part, and FIG. 3 is an explanatory diagram of an embodiment of the AC motor according to the present invention. 1... Rotor, 2... Stator, 3... Rotating shaft, 4... Bracket, 5, 6... Bearing, 7...
Belt, 8... Stator mounting hole, 9... Bracket mounting hole, 10... Bolt, 11... Pulley, 12, 13... Bearing mounting position.

Claims (1)

[Claims for Utility Model Registration] (1) In an electric motor that drives a load on which a force acts in a direction substantially perpendicular to the rotating shaft, the gap length between the stator and rotor is determined by the force exerted by the load on the bearing side near the load. An AC motor characterized by being narrow in approximately the same direction and wide in the opposite direction. (2) The alternating current motor according to claim 1, wherein the gap length on the side far from the load is widened in substantially the same direction as the force exerted by the load and narrowed on the opposite side. (3) The alternating current motor according to claim 1 or 2, wherein at least one of the mounting positions of the stator and the bearing in the bracket is offset from the center. (4) The AC motor according to claim 1 or 2 of the utility model registration claim, in which the mounting position of the bracket on the stator is shifted from the center. (5) The AC motor according to claim 1, 2, 3, or 4 of the utility model registration claim, in which the direction of the force due to the load and the direction in which the gap length is shifted are within a range of approximately 90 degrees. .