JPS6321188Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a permanent magnet rotor that can significantly improve the starting characteristics of a synchronous motor used in continuous rotation. The present invention relates to a permanent magnet rotor that is elastically supported so as to be able to vibrate.

As is well known, a permanent magnet rotor type synchronous motor uses a rotating magnetic field created by energizing the stator windings and a synchronous torque generated by the interaction with the magnetic poles of the permanent magnet rotor to generate a permanent motor. This is a motor in which the magnet rotor rotates at a synchronous speed. In addition,
In the present invention, the term "synchronous motor" is used to refer to a broad concept that includes step motors (step motors) that basically apply the same operating principle.

By the way, when the synchronous speed is high and the inertia of the rotor is large to some extent, or even if the inertia of the rotor itself is small to some extent but the inertia of the load carried by the rotor shaft is large to some extent, a narrowly defined synchronous motor that uses only permanent magnets as the rotor Even if the power switch is turned on, only vibration torque is generated and there is no starting torque. This is because even the maximum torque of the motor cannot accelerate the rotor to synchronous speed within a short period of time. However, if the power supply frequency is low, synchronous speed can be reached instantaneously.
A frequency-controlled permanent magnet synchronous motor takes advantage of this and starts the motor by sweeping the power supply frequency from a low frequency to a predetermined frequency. However, such speed control requires expensive electronic equipment.

Note that the same applies to the step motor. A step motor differs from a synchronous motor in the narrow sense in that it has a small rotor inertia and has multiple poles with a small spacing between magnetic poles so that it can be started with only synchronous torque. It will not start unless the startup circuit is activated, and it will be difficult to start even if the load is large beyond a certain level.

In a narrowly defined synchronous motor, in order to solve the above-mentioned difficulty in starting, the stator yoke is attached to the inner surface of the external bracket with an elastic support, so that the stator yoke can vibrate in the circumferential direction. Some have also been devised. However, the stator side has a large moment of inertia and is difficult to vibrate, requires considerable force to vibrate, and is difficult to vibrate only in the circumferential direction.

The present invention was developed in view of the actual state of the prior art, and its purpose is to:
An object of the present invention is to provide a permanent magnet rotor for a synchronous motor which has an extremely simple structure and is much easier to start than conventional ones.

That is, as shown in FIG. 1, for example, a conventional permanent magnet rotor includes a ring-shaped permanent magnet 1, a shaft 2, and an intervening member 3 (a rotor ring made of aluminum or hard plastic), which are press-fitted or bonded together. It was fixedly integrated by
The present invention is characterized in that a cushion material made of a polymeric material is used as an intervening member instead of a rigid rotor ring, and thereby a ring-shaped permanent magnet is supported so as to be able to rotate and vibrate with respect to the shaft.

The present invention will be explained in more detail below. FIG. 2 is a partially cutaway perspective view showing an embodiment of the permanent magnet rotor according to the present invention. A ring-shaped permanent magnet rotor 11 and a shaft 1 located at its central axis.
A cushion material 13a made of a polymeric material such as rubber or polyurethane foam is used as an intervening member that connects the parts 2 and 2. End disks 14 and 15 having a diameter slightly smaller than the inner diameter of the ring-shaped permanent magnet 11 are disposed on the shaft 12 at intervals approximately equal to the height of the ring-shaped permanent magnet 11, and are covered with the ring-shaped permanent magnet 11. Then, the interior space is filled with cushion material 13a. That is, the shaft 12 is elastically coupled to the ring-shaped permanent magnet 11 via the cushion material 13a, but is not bonded to the end discs 14, 15. However, this relationship is reversed, that is, the ring-shaped permanent magnet 11 is elastically coupled to the shaft 12 via the cushion material 13a, and the end disc 14,
15 may be in a non-adhesive state. Therefore, even if the shaft 12 is fixed, the ring-shaped permanent magnet 11 can rotate and vibrate around the shaft. The end disks 14 and 15 serve as guides for the trajectory of the rotational vibration of the ring-shaped permanent magnet 11, preventing unnecessary vibration in the radial direction, and even when the shaft 12 is arranged horizontally, the shaft 1
2 from eccentricity, and the cushion material 13
It also functions as a mold for filling a. Of course, the cushion material 13a is formed in advance,
It is also free to assemble by gluing or the like.

When a permanent magnet rotor with such a structure is incorporated into a synchronous motor, even if the load is large, the moment of inertia during rotational vibration of the ring-shaped permanent magnet 11 is extremely small, and therefore the shaft 12 is
Even if the ring-shaped permanent magnet 11 does not move much, it vibrates in the circumferential direction, and when the direction and timing of the elastic restoring force when the cushion material 13a is elastically deformed and the synchronizing torque match, the two strengthen each other and generate an extremely A large torque is generated, and the entire rotor rotates at an accelerated rate, leading to synchronous rotation. Therefore, startup becomes extremely easy.

This situation will become even clearer from the torque-frequency characteristic curve diagram in FIG. In the figure,
The broken line A shows the starting characteristic using the rotor of the conventional structure shown in Fig. 1, that is, the load torque of a motor that can be started in a completely one-to-one correspondence with the input signal frequency. Yes, dashed line B
is a continuous characteristic, that is, the relationship between the escape frequency at which a synchronously operating motor loses synchronization and the load torque. On the other hand, when the rotor having the structure according to the embodiment of the present invention is used, the starting characteristic greatly extends into the continuous rotation region as shown by curve C, and becomes a characteristic that is extremely close to the continuous rotational characteristic. In other words, even when carrying the same load, the product of this invention can be started at a higher frequency than the conventional product, and within the substantially expanded starting characteristic range (indicated by diagonal lines and symbol D). For example, even if the product is outside the startup characteristic range of conventional products, it can be restarted without using a restart circuit.

Therefore, the present invention, upon startup or restart,
When a step motor is used for constant-speed rotation applications where it does not necessarily have to rotate completely in one-to-one synchronization with clock pulses, it is suitable for use as a phono motor, for example. Of course, it can also be applied to ordinary synchronous motors.

Since the present invention is a permanent magnet rotor as described above, the structure is extremely simple, and since the permanent magnet is supported on the shaft so that it can rotate and vibrate freely, it is much easier to start up than conventional methods, and it is substantially The starting characteristics can be greatly expanded, and there are excellent practical effects such as no need for a special restart circuit when restarting.

The inner surface of the cushion material is fixed to the shaft, and the outer surface is fixed to the permanent magnet, so vibration in the axial direction is prevented, and end plates that fit into the permanent magnets are arranged on the end surfaces of the cushion material. Unnecessary vibration in the radial direction is prevented. In other words, only rotational vibration is allowed between the permanent magnet and the shaft, so there is no risk of the rotor colliding with the stator and causing noise or damage, and since the rotor and stator can be placed close together, motor efficiency can be improved. There is an effect that can be done.

Since the cushion material is uniformly provided over the entire circumference and exhibits viscoelastic behavior, it is possible to perform smooth rotational motion in response to the pulsating flow drive of the synchronous motor.

No special stopper member or the like is provided between the permanent magnet and the shaft, and there is no particular limit to the range in which rotational vibration can occur. It depends exclusively on the performance of the cushion material. Therefore, the stopper member does not collide with other members and generate noise when starting or stopping, and smooth starting is performed. This also leads to the ability to widen the torque range and drive frequency range, which brings about the extremely favorable effect of being able to use a motor with the same specifications under various operating conditions.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional rotor, and FIG. 2 is a partially cutaway perspective view of an embodiment of the rotor according to the present invention.
Figure 3 is a comparison song of the characteristics of the conventional product and the product of the present invention. 11...Ring-shaped permanent magnet, 12...Shaft, 13a...Cushion material.

Claims (1)

[Scope of utility model registration request] In a permanent magnet rotor in which a ring-shaped permanent magnet and a shaft located at its central axis are connected by an intervening member, the intervening member is a cushion material made of a polymeric material, and the inner surface thereof is connected to the shaft. A synchronous motor in which the outer surfaces are each fixed to a ring-shaped permanent magnet, an end plate that fits into the ring-shaped permanent magnet is arranged on the end surface, and the ring-shaped permanent magnet is supported with respect to a shaft so as to be able to rotate and vibrate freely. Permanent magnet rotor of motor.