JP2011083155A - Vibration reduction motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the problem with a motor, wherein a magnetic flux passing a gap during operation causes electromagnetic force between a stator core and a rotor core, a frame tends to deform when a mode order of the electromagnetic force is low, causing vibration, and large vibration and noise are generated if the frequency of electromagnetic force is identical with or close to the intrinsic oscillation frequency of the frame depending on operation condition. <P>SOLUTION: The vibration of a frame of a motor is reduced by deviating, in circumferential direction, an end of one of the stator core and the rotor core relative to the other end so that the electromagnetic mode is canceled. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a motor, and reduces vibration of a frame during operation.

  The motor is composed of a stator core, a rotor core, a coil, a shaft, and a frame.

  When the motor is operated, electromagnetic force acts on the stator core and the rotor core due to the magnetic flux passing through the gap, causing the frame to vibrate. FIG. 3 shows a mechanism in which the frame vibrates due to electromagnetic force and generates noise.

  The electromagnetic force acting on the stator core increases at a location where the gap has a high magnetic flux density, that is, a location where there is a magnetic pole. The electromagnetic force works to narrow the gap, and the stator core is pulled inward, so the iron core is deformed. Since the electromagnetic force is smaller in the place without the magnetic pole than in the place with the magnetic pole, the stator core deforms outward, contrary to the action of narrowing the gap near the magnetic pole. The distribution of electromagnetic force that deforms the stator core is represented by a mode corresponding to the number of forces that pull the core inward. The case where two places are pulled as shown in FIG. 4 is referred to as mode 2 or secondary mode. Similarly, when there are three places, mode 3 is set.

  In the case of a distributed winding motor, since the magnetomotive force distribution is a distribution close to a sine wave, the magnetic pole strength is equal between the N pole where the magnetic flux exits the iron core and the S pole where the magnetic flux enters the iron core. Therefore, an electromagnetic force mode equal to the number of poles is generated.

  In the case of a concentrated winding motor, each phase winding is wound around one tooth, so the magnetomotive force distribution is not sinusoidal. Taking the instant at which the U-phase current is maximum in the three-phase winding as an example, when the U-phase current is maximum, 1/2 current flows in the other V-phase and W-phase. Comparing the strengths of the magnetic poles, when the U-phase teeth make the N pole, the V-phase and W-phase teeth each make the S pole of 1/2 strength. Therefore, at this moment, the only place where the electromagnetic force is working is the U-phase teeth, and the mode generates an electromagnetic force mode of the order of 1/2 the number of poles.

  When the mode order of electromagnetic force is low, the frame is easily deformed, which causes vibration. Further, when the frequency of the electromagnetic force coincides with or is close to the natural frequency of the frame depending on the operating conditions, large vibration and noise are generated.

  A motor with a small number of poles generates a low-order electromagnetic force mode, so that vibration and noise are likely to occur. In addition, it is necessary to consider a higher-order electromagnetic force mode for a large machine compared to a small machine.

  As a method for reducing the vibration of the frame due to the electromagnetic force, a method of increasing the rigidity of the frame, changing the natural frequency by processing or adding material to the frame, and the like is known as a conventional technique.

JP 2002-171718 A

Induction machine electromagnetic noise analysis technical investigation special committee, “The Institute of Electrical Engineers of Japan Technical Report No. 1048”, Institute of Electrical Engineers of Japan, 2006, p. 4

  However, since the conventional technique is a vibration reduction method for the generated electromagnetic force mode, there is a problem that the generated electromagnetic force mode itself cannot be reduced.

According to the invention of claim 1,
In motors such as AC motors and DC motors, motors that reduce frame vibration by shifting one end of the stator core and rotor core in the circumferential direction so as to cancel the electromagnetic force mode relative to the other end .

According to the invention of claim 2,
The motor according to claim 1, wherein an angle at which the iron core is shifted is an electrical angle of 90 degrees.

According to the invention of claim 3,
2. The motor according to claim 1, wherein an angle at which the iron core is shifted is an electrical angle of 180 degrees.

The main feature of the present invention is that one end of the stator core and the rotor core is shifted in the circumferential direction with respect to the other end in order to prevent the electromagnetic force mode from being generated in the motor.
For example, the stator core and the rotor core may be shifted in the circumferential direction with the central portion of the thickness being the boundary. The low-order electromagnetic force mode can be shifted in the circumferential direction so as to cancel out, and the vibration of the frame and the noise generated by the vibration can be reduced.

  Since the motor of the present invention has two iron cores having different positional relations in the circumferential direction, there is an advantage that the phase of the generated electromagnetic force mode is shifted.

  The vibration of the frame can be reduced by shifting the iron core so that the low-order electromagnetic force mode that causes the vibration is canceled. By reducing the vibration of the frame, it is possible to reduce the noise generated by the vibration.

  In addition to induction motors, synchronous motors, and switched reluctance motors, the present invention can also be applied to DC motors.

  Since a mode having an order twice that of the canceled mode order is generated, it is difficult to reduce the vibration caused by the high-order mode in a large machine that has a problem up to the high-order mode.

Explanatory drawing which showed the iron core structure. Explanatory drawing which showed the cross section of the motor. Explanatory drawing which showed the mechanism in which vibration and noise generate. Explanatory drawing which showed the mode order. An explanatory view showing an electromagnetic force mode when the present invention is applied to a four-pole distributed winding motor. Explanatory drawing which showed the electromagnetic force mode when this invention is applied to a 6 pole concentrated winding motor.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing the structure of an iron core and a coil. FIG. 2 is a cross-sectional view of the present invention.

  The stator core and the rotor core are divided into two at the center of the stack. The two cores are a pair of the stator core 1a and the rotor core 2a, and a pair of the stator core 1b and the rotor core 2b. have. The set of the stator core 1b and the rotor core 2b is shifted from the set of the stator core 1a and the rotor core 2a so as to have a phase difference in the circumferential direction. A phase difference occurs in the mode.

  Based on the set of the stator core 1a and the rotor core 2a, the set of the stator core 1b and the rotor core 2b is shifted by the same angle so that the mode causing the vibration is canceled.

  In order to shift the phase of the electromagnetic force, the position of the coil 3 is changed, for example, in a twisted manner between the two iron cores.

  FIG. 5 is a diagram showing an electromagnetic force mode when the method of the present invention is applied to a 4-pole distributed winding motor. In the distributed winding, an electromagnetic force mode equal to the number of poles is generated. Therefore, since a quadruple mode is generated in a 4-pole distributed winding induction motor or a permanent magnet synchronous motor, a set of a stator core 1b and a rotor core 2b is used instead of a set of the stator core 1a and the rotor core 2a. By shifting the electrical angle by 90 degrees, the fourth-order modes generated by the two iron cores having different positional relationships are canceled each other.

  In the case of the induction motor, the secondary conductor of the rotor connects the rotor core 2a and the rotor core 2b so as to change the position in the same manner as the coil. Alternatively, end rings are provided at both ends of each iron core.

  When the mode order causing vibration is equal to the number of poles, the iron core can be canceled by shifting the electrical angle by 90 degrees.

  FIG. 6 is a diagram showing an electromagnetic force mode when the method of the present invention is applied to a 6-pole concentrated winding motor. In the concentrated winding, an electromagnetic force mode of the order of 1/2 the number of poles is generated. Since the concentrated winding 6-pole permanent magnet synchronous motor generates the tertiary mode, the stator core 1b and the rotor core 2b are shifted by an electrical angle of 180 degrees with respect to the set of the stator core 1a and the rotor core 2a. Thus, the tertiary modes generated by the two iron cores having different positional relations cancel each other.

  When the mode order causing vibration is equal to ½ of the number of poles, the iron core can be canceled by shifting the electrical angle by 180 degrees.

  According to the present invention, since vibration and noise during motor driving can be reduced, the present invention can be effectively used for many industrial devices.

1, 1a, 1b Stator core 2, 2a, 2b Rotor core 3 Coil 4 Coil end 5 Shaft 6 Frame 7 Electromagnetic force mode of 4-pole distributed winding motor stator core 1a and rotor core 2a 8 4 poles Electromagnetic force mode of the set of the stator core 1b and the rotor core 2b of the distributed winding motor 9 Electromagnetic force mode of the set of the stator core 1a of the 6-pole concentrated winding motor and the rotor core 2a 10 Stator of the 6-pole concentrated winding motor Electromagnetic force mode of the set of iron core 1b and rotor core 2b

Claims (3)

  In motors such as AC motors and DC motors, the vibration of the frame is reduced by shifting one end of the stator core and rotor core in the circumferential direction so as to cancel the electromagnetic force mode with respect to the other end. A motor characterized by   2. The motor according to claim 1, wherein an angle at which the iron core is shifted is an electrical angle of 90 degrees. 2. The motor according to claim 1, wherein an angle at which the iron core is shifted is an electrical angle of 180 degrees.

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