JPS5837787B2 - small motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small inductor type motor that continuously rotates a two-pole rotor.

The applicant of this application previously filed patent application No. 1151 filed in 1975.
In No. 99 "Small Motor", two salient poles are provided on each of a pair of stator magnetic pole plates facing each other with the rotor in between, and a cut arrow part that almost occupies the space between the two salient poles is recessed, and this cut arrow part is attached to the rotor. The maximum gap is approximately equal to the radius of the rotor.

This configuration makes it possible to realize a self-starting continuous rotation motor, which equalizes the force acting on the rotor when energized, allowing the rotor to rotate smoothly despite the small number of magnetic poles and enable low input drive. did.

However, in this prior invention, if the rotor is placed at the geometric center of the salient poles, there is a possibility that the rotor will stop with its poles matching the line passing through the center of the notch, although the probability is low. In such cases, the rotor cannot be started even if there is input to the coil.

This is the dead point. The present invention further improves this prior invention, and aims at preventing the occurrence of dead points, increasing torque, and smoothing the rotation of the rotor.

Before explaining the present invention, the above-mentioned invention of the prior application, which is the premise thereof, will be explained.

As shown in FIG. 1, the stator 1 has a substantially U-shape with a pair of legs extending parallel to each other.

The tips of both legs 1a, la of this stator 1 are stator magnetic pole plates 2, 3, and a permanent magnet rotor 4 magnetized to N, 82 poles is rotatably arranged between them. An excitation coil 5 is attached to the section.

Both stator magnetic pole plates 2 and 3 each have two salient poles 2a.
, 2b and 3a > 3b, each salient pole 2a,
2b, 3a, 3b are arranged symmetrically around the rotor 4 at approximately equal intervals.

Notches 2C and 3C are recessed between salient poles 2a and 2b and between salient poles 3a and 3b, and these notches 2C and 3C are provided between salient poles 2a and 2b or between salient poles 3a and 3b. is formed large enough to occupy an angular range slightly smaller than its opening angle.

In this example, the notches 2C and 3C are recessed in an arc shape, the radius of the arc is approximately equal to the radius of the rotor 4, and the centers R and R are located near the outer periphery of the rotor 4 on line CC.

The C-C line is the salient pole 2a, 2b or the salient pole 3a, 3b
This is a straight line that passes through the center of the rotor 4 at approximately equal distance from the center of the rotor 4.

When there is no input to the coil 5, the N and S poles of the rotor 4 are located on the A-A line or the B-B line connecting the salient poles 2a and 3a or the salient poles 2b and 3b with respect to the stator magnetic pole plates 2 and 3. and come to a stable standstill.

That is, when no current is applied, each salient pole 2a, 2b, 3a
, 3b exert static torque on the rotor 4 as shown in Figure 7A.

The angle θ is a clockwise angle from a line parallel to the legs 1a, 1a and passing through the center of the rotor 4 to a pole of the rotor 4 in FIG.

The static torque of the stator magnetic pole plates 2, 3 as a whole to the rotor 4 is the sum of the static torques of the salient poles 2a, 2b, 3a, 3b, as shown in FIG. 7B.

In FIG. 7B, the arrow drawn in the static torque curve indicates the pole of the rotor 4 (N
Either pole or south pole may be used.

) is within an angular range of 45° on both sides of the salient pole 2b, which means that the rotor receives static torque toward the salient pole 2b and eventually comes to a stable standstill opposite the salient pole 2b. ing.

The same applies to the other salient poles 2a, 3a, 3b, and the rotor 4 is stably stationary at a position where its N and S poles face the salient poles 2a, 3a or 2b, 3b.

Therefore, the A-A line or the B-B line connecting the salient poles 2a and 3a or the salient poles 2b and 3b becomes the static stability line of the rotor 4 when no current is applied.

On the other hand, considering the stator magnetic pole plates 2 and 3 in the energized state, the entire stator magnetic pole plates 2 and 3 are alternately excited to the north pole or the south pole.

That is, not only the salient poles 2a, 2b, 3a, and 3b are partially excited, but also the notched portions 2c and 3c between them are similarly excited.

Then, the salient poles 2a, 2b, the notch 2C, and the salient poles 2a, 2
b, notch 2C, salient poles 3a, 3b, and notch 3c are C
Since it is located symmetrically with respect to the -C line, when looking at the stator magnetic pole plates 2 and 3 as a whole, the C-C line becomes the dynamic magnetic center line when energized.

Next, a transient state in which the rotor 4 reaches steady rotation from the stationary state shown in FIG. 1 will be explained.

In FIG. 1, when the first pulse is applied to the coil 5 and the stator magnetic pole plates 2 and 3 are excited to the S and N poles, respectively, as shown in FIG. 2b and 3b, but the stator magnetic pole plate 2
, 3 is also repulsed by the entire body and swings counterclockwise.

The next pulse arrives before the rotor 4 has oscillated only to the position indicated by the broken line, and the stator magnetic pole plates 2 and 3 are reversely excited to the north and south poles as shown in FIG.

Then, the rotor 4 is largely influenced by the salient poles 2b and 3b, and is also attracted by the entire stake magnetic pole plates 2 and 3, so that it is pulled back clockwise.

At this time, the rotor 4 oscillates more than the previous maximum deflection angle, and when it reaches the maximum deflection position (the broken line position in Figure 3), the stator magnetic pole plates 2 and 3 are moved by the next pulse as shown in Figure 4. It is reversely excited to S pole and N pole.

In Fig. 4, the rotor 4 receives a clockwise force from the salient poles 2b + 3b and their vicinity, but receives a counterclockwise rotational force from other parts of the stator magnetic pole plates 2 and 3, and the total In this case, the latter force exceeds the former force, and the rotor 4 swings counterclockwise.

The rotor 4 receives a braking force from the salient pole 2 b t 3 b until the pole passes the salient pole 2 b t 3 b, but from the moment the rotor 4 passes the salient pole 2 b , 3 b , this salient pole 2 b r 3 It also receives a counterclockwise force from b and swings as shown by the broken line.

In this way, the rotor 4 repeatedly oscillates each time a reversal pulse arrives, and the oscillation angle gradually increases.

Then, the poles of the rotor 4 finally cross the C-C line, which is the dynamic magnetic center line, as shown in FIG.
, 3 are excited to the S and N poles, and when this state is reached, the rotor 4 begins to rotate clockwise.

In FIG. 5, the rotor 4 initially has salient poles 2a,
3a receives the braking force, but the stator magnetic pole plates 2 and 3
The sum of the clockwise force received from other parts of the rotor 4 and the clockwise inertia force of the rotor 4 when the rotor 4 reaches the position shown in FIG. 5 exceeds the braking force, and the rotor 4 rotates clockwise. When the rotor 4 passes through the salient poles 2a and 3a, it is also repelled from the salient poles 2a and 3a and receives a clockwise force.

As the poles of the rotor 4 approach the salient poles 3b and 2b, they receive the suction force from the salient poles 3b and 2b, causing a clockwise rotational force (7 J [] speed), and the poles of the rotor 4 After passing through b and 2 b, it now receives a braking force due to suction.

As shown in FIG. 6, when the rotor 4 rotates, the stator magnetic pole plates 2 and 3 are reversely excited to the north and south poles, and the rotor 4 enters a steady rotation state in the clockwise direction.

In this steady rotation state, the polarity of the input signal to the coil 5 shown in FIG. 1 is reversed at an angular timing when the rotor 4 faces or slightly passes the salient poles 2a and 3a.

In order to effectively obtain the self-starting operation of the rotor 4 as described above, in this embodiment, the inverting input frequency to the coil 5 is
It is made to approximately match the natural frequency of the rotor 4 based on the static magnetic coupling force between the stator magnetic pole plates 2, 3 and the rotor 4 when no current is applied.

With this, it is possible to cause the rotor 4 to resonantly oscillate at the time of startup and gradually increase its deflection angle by inputting a small current.

Note that the rotational direction of the rotor 4 in this motor is determined by the rotational direction when the rotor 4 crosses the dynamic magnetic center line (C-C line) when swinging, so it is not necessarily constant.

By the way, if we consider the steady rotation of the rotor 4 in the clockwise direction, as mentioned above, during this steady rotation, the rotor 4 rotates at a timing when the poles of the rotor 4 face or slightly pass the salient poles 2a and 3a (8th B). 8A), the stator pole plates 2, 3 are subjected to a dynamic torque relative to the rotor 4 as shown by the solid line in FIG. 8A.

This dynamic torque is a virtual torque obtained only by energizing the coil 5 without considering the static torque of the stator magnetic pole plates 2 and 3.

In reality, the static torque of the stator pole plates 2, 3 affects the rotor 4.

This static torque affects the rotor 4 little by little due to the existence of the real poles 2a, 2b, 3a, 3b and the notches 2c, 3c, and the dynamic torque that actually acts effectively on the rotor 4 is shown in FIG. become that way.

In FIG. 9, the left hatched area acts as a driving force for rotation of the rotor 4, and the right hatched area acts as a braking force for the rotor 4.

In the small motor configured as described above, when the rotor 4 is placed at the geometric center of the salient poles 2 a + 2 b + 3 a t 3 b, although the probability is low, the rotor 4
may stop on the C-C line when no power is applied.
In such a case, the rotor 4 cannot be started even if there is an input to the coil.

This is the dead point.

In addition, the stator 1 which induces magnetic flux to the stator magnetic pole plates 2 and 3
Normally, the stator 1 has at least a small portion extending in the C-C line direction, but in this case, the stator 1 is U-shaped, and its legs 1a, 1a extend in a direction perpendicular to the C-C line. ing.

Therefore, due to the relationship of the magnetic flux guiding path by this U-shaped stator 1, the magnetic flux from the salient poles 2 b and 3 a on the side of the legs la and 1 a is somewhat stronger than that of the salient poles 2 a > 3 b on the opposite side. Become.

Therefore, if the rotor 4 is arranged at the geometric center of the salient poles 2a, 2b, 3a, 3b, the salient poles 2a, 2b
, 3a, 3b, an imbalance occurs in the force acting on the rotor 4, which causes the rotor 4 to oscillate in the radial direction, which impedes smooth rotation of the rotor and also makes it impossible to extract high torque.

Therefore, in the present invention, as shown in FIG.
A point P shifted by a distance V in the direction away from the coil 5 from the geometric center O of a, 2b, 3a, and 3b was set as the rotation center of the rotor.

In the embodiment shown in FIG. 10, parts corresponding to the small-sized motor of the prior invention shown in FIG.

In this way, by slightly offsetting the center of the rotor 4, each salient pole 2a t 2b ? 3a
, 3b and the rotor 4, the salient poles 2a, 3b approach the rotor 4 by the distance that the salient pole 2b t3a moves away from the rotor 4, so when no current is applied, the rotor 4 It receives more static magnetic attraction force from the salient poles 2 a t 3 b.

Even if the rotor 4 tries to stand still along the magnetic pole C line, it is difficult to maintain the balance of static magnetic force at that position because it is close to the salient poles 2a and 3b, and for this reason, the A/
It will come to a standstill along either the A/line or the B/B/ line.

That is, the probability of dead points occurring is reduced.

To explain this in more detail, each salient pole 2a,
2b, 3a, and 3b exert static torque on the rotor 4 as shown in Figure 11A.

The static torque of the stator magnetic pole plates 3, 4 as a whole to the rotor 4 is the sum of the static torques of the salient poles 2a, 2b, 3a, 3b, as shown in FIG. 11B.

Comparing these FIGS. 11A and 11B with the above-mentioned FIGS. 7A and 7B, the torques due to the salient poles 2 a and 3 b are small, and the torques due to the salient poles 3 a and 2 b are small ( 11A), the angle 90 that may result in a dead point as shown in FIG. 11B.
The slope of the torque curve becomes steep at the 270° position and the 270° angle position, and in the vicinity of these angles, the variation in Φ torque per angle is larger in the case shown in Fig. 11B of the present invention than in the case shown in Fig. 7B of the prior invention.

This means that because the torque near the C/C/ line changes suddenly due to a slight difference in angle, the probability of stopping along the C'-C' line is extremely small if the balance of static magnetic force is maintained. It shows that.

In other words, it is effective in eliminating dead points.

On the other hand, to explain the energized state, the salient poles 2 b > 3 a that generate strong magnetic flux move away from the rotor 4, and the salient poles 2 a and 3 b that generate weak magnetic flux approach the rotor 4. Salient poles 2a, 2b, 3a, 3
The dynamic magnetic action of b on the rotor 4 is equalized.

Therefore, the acceleration force and braking force that the rotor 4 receives during its rotation are received equally and in a well-balanced manner by all the salient poles 2a, 2b + 32, 3b, so the rotation of the rotor 4 becomes smoother and the torque is reduced. In addition, the rotor no longer wanders in the radial direction due to unbalanced dynamic magnetic action from each salient pole, reducing axial loss.

Measurement results confirming this are shown in FIGS. 12 and 13.

FIG. 12 is a characteristic diagram showing the relationship between input voltage and torque.

Curve a is the characteristic of the motor having the configuration shown in Figure 10, and curve b is the characteristic of the motor having the configuration shown in Figure 1, both of which use a stator with the dimensions shown in Figure 14 and have a rotor diameter of zO mm. .

In curve a, a motor is used in which the deviation amount V between the center O of the four salient poles and the center P of the rotor is 0.3 mm IJ meters.

Further, in curve b, a motor whose centers O and P coincide is used.

The rotation speed of the rotor is 3 revolutions per second.

The input waveform to the coil is 1.5cm as shown in Figure 15.
As shown in the inverted input waveform of , one cycle is 125 milliseconds, and was measured by changing the voltage from 1.3 to 1.7.

As is clear from this characteristic curve, the characteristic curve a of the motor (invention) shown in Figure 10 is the same as that of the motor (before improvement) shown in Figure 1.
Compared to characteristic curve b, torque improvement was observed at any input voltage.

Also, Figure 13 shows 1 drive voltage (7) and dead point (
12 is a graph showing the relationship between the occurrence rate of DP) and the probability of not rotating, that is, the occurrence rate of DP, which was measured by repeatedly turning on and off under the same conditions as in FIG. 12.

Curve C is the DP generation rate of the motor shown in Figure 10 (invention), and curve d is the DP generation rate of the motor shown in Figure 1 (before improvement).

As is clear from this relationship diagram, the motor of the present invention has a significantly lower dead point occurrence rate than the motor before the improvement. For example, when the input voltage is 1.5 to 1.7 V, the dead point The occurrence rate is 0. Or it can be seen that it is almost 0.

As described in detail above, according to the present invention, each of the pair of stator magnetic pole plates connected to the U-shaped yoke has two salient poles, and the distance between the two salient poles is approximately In a small motor in which a large occupying notch is recessed and each salient pole is positioned at approximately equal intervals on the circumference, the center of the rotor is connected to the coil (or By simply shifting the rotor 4 in the direction away from the yoke, it is possible to reduce the number of situations in which the rotor 4 stops at a dead point, and in addition, the rotation of the rotor 4 can be made even smoother, and the torque can be improved.

[Brief explanation of drawings]

Figures 1 to 9 relate to the small motor of the prior invention, which is the basis of the present invention; Figure 1 is a plan view thereof, and Figure 2 is a plan view thereof;
6 are explanatory diagrams of the operation, FIG. 7A is a characteristic diagram showing the static torque provided to the rotor by each salient pole of the stator magnetic pole plate, and FIG. 7B is a characteristic diagram showing the static torque (each salient) of the stator magnetic pole plate as a whole to the rotor Fig. 8A is a characteristic diagram showing the dynamic virtual torque of the stator magnetic pole plate when energized is superimposed on the static torque, Fig. 8B is an input signal waveform diagram, and Fig. 9 The figure is a characteristic diagram showing the effective torque which is the sum of the dynamic virtual torque and the static torque in FIG. 8A. 10 to 15 relate to a small motor improved according to the present invention, in which FIG. 10 is a plan view, and FIG. 11A is a characteristic diagram showing the static torque provided to the rotor by each salient pole of the stator magnetic pole plate. Fig. 11B is a characteristic diagram showing the static torque (sum of static torque due to each salient pole) for the rotor as a whole of the stator magnetic poles, Fig. 12 is a torque characteristic diagram,
Figure 13 is a diagram showing the relationship between voltage and dead point occurrence rate.
FIG. 4 is a plan view of the stake used in the measurements in FIGS. 12 and 13, and FIG. 15 is an input waveform diagram of the same. DESCRIPTION OF SYMBOLS 1... Stator, 1a... Stator leg, 2, 3... Stator magnetic pole plate, 2a,
2b, 3a, 3b... Salient pole, 2C, 3
C...Notch, 4...Rotor, 5...
... Coil, O ... Geometric center of salient pole arrangement, P ... Center of rotor, ■ ... Displacement between center O and center P.

Claims (1)

[Scope of Claims] Consisting of a permanent magnet rotor magnetized to 1N, 82 poles, a stator having a pair of stator magnetic pole plates facing each other with this rotor in between, and a coil for exciting this stator; In a small synchronous motor in which a motor is continuously driven to rotate, each stator magnetic pole plate is formed at each end of both legs extending in parallel of a U-shaped stator. Each of the two salient poles is formed so as to be located at approximately equal intervals on the circumference, and the maximum gap between the two salient poles of each stator magnetic pole plate that substantially occupies the space therebetween and with respect to the rotor is formed. A notch substantially equal to the radius of the rotor is recessed, and the center of the rotor is located at a position offset from the geometric center of the four salient poles in a direction away from the coil. small motor.