JPS6233827B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a synchronous motor, and particularly to a synchronous motor in which a stator and a rotor face each other face to face.

[Background Art] Conventional synchronous motors are configured to reduce mechanical loss, and because this motor has a large output despite its small inertia, it is likely to cause twitching during no-load rotation. , and was a source of vibration and noise. The main reason for this is that when the rotor torque is large and the rotor is light, the response becomes faster, so the rotor turns too much due to an overshoot phenomenon and the brakes are momentarily applied. In other words, there was a tendency to overdamping, one bumping occurred per pitch of the magnetic pole teeth, and the vibration was large.

By the way, in a so-called face-to-face type synchronous motor in which the stator and rotor face each other, mechanical loss occurs on the thrust face because the rotor magnetic pole face and the stator magnetic pole face attract each other. The loss is in a state where the vibration torque is consumed and absorbed, making it easier to obtain stable rotation.
However, even in this case, when the gap between the rotor and stator becomes large, the suction force decreases and the mechanical loss on the thrust surface is extremely reduced, making it impossible to control the cocking and eventually causing disturbances. I was getting used to it. On the other hand, even if the air gap between the rotor and stator is appropriate, when used in a high-temperature atmosphere (for example, 80°C or higher), the viscosity of the lubricating oil will drop significantly and mechanical loss will decrease. Therefore, the locking control ability also decreases, eventually causing disturbances.

When such disturbance occurs, if an appropriate load is applied to the rotor, an appropriate mechanical loss will occur and stable rotation will be obtained. For this reason, there have conventionally been some devices that apply mechanical friction to the rotor shaft by bringing a spring into contact with the rotor shaft. However, since the static friction increases, the starting torque is consumed, resulting in a smaller starting torque, and the contact part of the spring wears out, making it impossible to maintain the same state over a long period of time. It had the disadvantage of being close to

[Object of the Invention] The present invention has been made in view of the above-mentioned reasons, and its purpose is to reduce twitching (uneven rotation, irregular adjustment, etc.) by applying a magnetic brake, and to increase the stable rotational voltage range. The goal is to provide a synchronous motor that can be expanded.

[Disclosure of the Invention] The synchronous motor of the present invention is a surface-facing type synchronous motor that has a U-shaped tip portion of a stator bent in a U-shape, and has an arc along the circumferential surface of a rotor, and An arc-shaped magnet having a thickness that protrudes from both the upper and lower surfaces of the rotor is magnetized in the vertical direction and fixed in such a way that it is close to the rotor in the radial direction and protrudes from both the upper and lower surfaces of the rotor when viewed from the side. It is characterized by

According to the present invention, by intersecting the magnetic flux of the arc-shaped magnets in the thickness direction of the rotor, a magnetic brake can be applied to the rotor according to the rotational speed of the rotor, thereby causing uneven rotation. This makes it possible to expand the stable rotational voltage range by reducing disturbances (such as disturbances).

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

Reference numeral 1 denotes a stator, which is made by bending a magnetic plate material into a U-shape, and has multipolar magnetic pole teeth 2 attached to its upper surface (one of two opposing surfaces). Reference numeral 3 denotes a rotor made of permanent magnets, in which different poles are alternately magnetized in the circumferential direction, and the stator 1 is arranged so that the magnetic pole surface faces the multipolar magnetic pole teeth 2.
It is set up opposite. 4 is a bearing made of a sintered alloy and impregnated with lubricating oil. A cylinder 5 made of a magnetic material is press-fitted into the center hole of the coil frame 6 to form a central magnetic path, and the bearing 4 is press-fitted into the center hole of the cylinder itself.
A coil 13 is wound around the coil frame 6, and both ends thereof are connected to terminals 12 provided on the coil frame 6. 7
is an outer frame made of synthetic resin, and has a coil frame accommodating portion approximately in the center.

Then, the coil frame 6 is inserted and housed in the outer frame 7,
With these upper and lower surfaces aligned, insert the stator 1 from the side, and insert the shaft 8 fixed to the rotor 3 into the bearing 4.
Insert into. Reference numeral 9 denotes a cover made of synthetic resin, on the inside of which an arcuate magnet 10 (described later) is fixed, and the rotor 3 is
A synchronous motor as shown in FIG. 2 is constructed by attaching it to the outer frame 7 so as to protect it. Note that a protrusion 11 may be provided on the inside of the cover 9, and the protrusion 11 may be inserted and locked into a hole provided in the stator 1. Specifically, a guide protrusion 14 for the stator 1 is provided on the upper side wall of the outer frame 7,
An inclined surface 15 is provided on the side where the stator 1 is inserted to facilitate the insertion work. Furthermore, the stator 1 is provided with a convex portion 16, and when inserted into the coil frame 6, the convex portion 16
6 and the inclined surface 15 come into contact with each other, the stator 1 is pushed out, and the tip 17 of the stator 1 touches the upper end 1 of the cylinder 5.
8 , the upper end portion 18 fits into the central hole 19 of the stator 1 due to the spring action of the stator 1 , and the convex portion 16 fits into the groove 20 of the outer frame 7 .

Next, the arcuate magnet 10 will be explained in detail. The arc-shaped magnet 10 is made of, for example, ferrite, has an arc along the circumferential surface of the rotor 3, and has a thickness that projects from both the upper and lower surfaces of the rotor 3. This arc length is equal to three magnetic poles of the stator 1. Further, the arc-shaped magnet 10 has N and S poles magnetized in the upper and lower thickness direction (same direction as the thickness of the rotor 3), and the U-shaped tip of the stator 1 adjacent to the rotor 3 in the radial direction. 1 (at a position corresponding to point A in FIG. 1), and is fixed to the inside of the cover 9 so that both upper and lower end surfaces protrude from both upper and lower surfaces of the rotor 3 when viewed from the side. Note that the arc-shaped magnet 10 is attached to the stator 1
It may be fixed on the U-shaped tip of the.

The magnetic flux generated by the arcuate magnet 10 flows from its north pole to the south pole of the rotor 3 and returns to the south pole. On the other hand, the magnetic flux generated by the rotor 3 returns from its north pole to its north pole through the south pole, the air gap, the magnetic pole teeth 2 of the stator 1, and the air gap. Therefore, the arc-shaped magnet 10
The magnetic flux caused by the rotor 3 intersects with the magnetic flux caused by the rotor 3, and when the rotor 3 rotates, it acts on the rotor 3 as a magnetic braking force. Further, the magnitude of this magnetic braking force is determined according to the rotational speed of the rotor 3.

Looking microscopically at the rotational state of this type of synchronous motor during operation, the relationship between the rotation angle and rolling time of the rotor 3 is pulsating as shown by curve a in Figure 5, and this pulsation is If it becomes too large, it will cause disturbances, but by applying an appropriate load to it, it will become like the curve b in Figure 5, which will reduce the twitching and allow smooth rotation. Therefore, by applying a brake to the movement of the rotor 3 as shown in curve a in FIG. 5 when there is no brake element, curve b is obtained. Furthermore, the fifth
Straight line c in the figure represents the synchronous speed.

FIG. 6 shows the relationship between the voltage applied to the motor and the air gap between the magnetic pole teeth 2 of the stator 1 and the magnetic pole faces of the rotor 3. The motor rotates stably and synchronously within the range shown by the solid line. FIG. 6a shows a case where there is no brake element, for example, when the gap length is 0.3 mm, when the applied voltage is increased and reaches point 21, synchronous pull-in is performed and stable synchronous rotation is obtained. When the applied voltage is further increased and reaches point 22, the oscillation increases and eventually disorder occurs and synchronous rotation is no longer possible, and when point 23 is reached, the state returns to synchronous rotation again. If the air gap length is reduced to about 0.2 mm, the force with which the magnetic pole surface of the rotor 3 is attracted to the magnetic pole teeth 2 of the stator 1 increases, and mechanical loss on the thrust surface increases, resulting in points 21' to 21'. Stable rotation can be obtained within an applied voltage range of 24'. Furthermore, if this gap length is made extremely small, the thrust loss becomes excessive, the starting voltage becomes high as shown at point 21'', and the stable rotational voltage range becomes narrow.

FIG. 6b shows the present invention, that is, the case where a magnetic brake element using an arcuate magnet 10 is added. The magnitude of the magnetic brake by the arc-shaped magnet 10 is determined according to the rotational speed of the rotor 3, so static friction at the time of starting is irrelevant, and therefore the starting voltage is the same as when there is no brake element. Furthermore, when the rotor 3 rotates, a magnetic braking force of a magnitude corresponding to the rotational speed is applied to the rotor 3, so if the air gap length is up to about 0.4 mm, it is possible to prevent cocking even between points 22 and 23. It rotates stably, and the voltage that causes disturbances on the high voltage side also increases. In other words, the present invention can reduce twitching (uneven rotation, irregular adjustment, etc.) and expand the stable rotational voltage range.
In addition, vibration and noise can also be reduced by reducing twitching. Furthermore, when providing the arc-shaped magnet 10, there is no need to make any changes to the structure of the electric motor.

Note that when manufacturing variations are considered, it is desirable that the gap length be as large as possible. In order to obtain a desired magnetic braking force, the optimum value is selected by changing the shape of the arc-shaped magnet 10 or by adjusting the position between the arc-shaped magnet 10 and the rotor 3. That is, regarding the shape, to increase the magnetic braking force, the arc length is lengthened, and to decrease it, the arc length is shortened, and regarding position adjustment, to increase the magnetic braking force, the arc-shaped magnets 10 are moved closer and made smaller. will cause them to defect. The vertical thickness of the arc-shaped magnet 10 is important in order to intersect its magnetic flux in the thickness direction of the rotor 3, but since the range of the air gap length cannot be set so large, the thickness of the rotor 3 ends up being It will be about 1.5 to 3 times the size.

[Effects of the Invention] The synchronous motor of the present invention is a surface-facing type synchronous motor, which has an arc along the circumferential surface of the rotor on the U-shaped tip of the stator bent in a U-shape, and An arc-shaped magnet having a thickness that protrudes from both the upper and lower surfaces of the rotor is magnetized in the vertical direction and fixed in such a way that it is close to the rotor in the radial direction and protrudes from both the upper and lower surfaces of the rotor when viewed from the side. Because the magnetic flux of the arc-shaped magnet intersects in the thickness direction of the rotor, a magnetic brake is applied to the rotor according to the rotational speed of the rotor, which causes uneven rotation and irregular rotation. etc.), which expands the stable rotational voltage range.In addition, vibration and noise can also be reduced by reducing cocking, and furthermore, the provision of arc-shaped magnets does not require any changes to the structure of the motor. It has the advantage that there is no need to add

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing one embodiment of the present invention, FIG. 2 is a cross-sectional view of the same as seen from the side, and FIG.
The figure is a plan view, FIG. 4 is a perspective view showing the relative position of the rotor and the arc-shaped magnet, FIG. A is a model without a magnetic brake, and b is a model with the proposed magnetic brake added. DESCRIPTION OF SYMBOLS 1... Stator, 2... Multi-pole magnetic pole tooth, 3... Rotor, 10... Arc-shaped magnet, 17... Tip part.

Claims (1)

[Claims] 1. A synchronous motor in which multi-polar magnetic teeth are attached to the upper surface of a stator bent in a U-shape, and a rotor is disposed so that the multi-pole magnetized magnetic pole face faces the multi-polar magnetic teeth. , an arc-shaped magnet having an arc along the circumferential surface of the rotor on the U-shaped tip of the stator and having a thickness protruding from both upper and lower surfaces of the rotor is magnetized in the vertical direction. A synchronous motor characterized by being fixed to a rotor in a manner that is close to the rotor in a radial direction and protrudes from both upper and lower surfaces of the rotor in a side view.