JPS62236349A - Dc motor - Google Patents

Abstract

PURPOSE:To eliminate the dead point of a rotor for a DC motor by providing magnetic flux strain means so that composite rotary torque generated by first and second phase coils becomes a predetermined electric angle or larger. CONSTITUTION:The densities of a magnetic flux crossing first and second coils 10a, 10b, 11a, 11b are so deformed that composite rotary torque generated by the forward and backward currents of the coils 10a, 10b, 11a, 11b becomes 180 deg. or larger of electric angle. The magnetic flux is generated by pairs of magnets 7a, 8a of a main pole and magnets 7b, 8b of an interpole. A position detecting ringlike permanent magnet 18 is mounted on the motor axial ends of the permanent magnets 7a, 7b, 8a, 8b. An angle formed of the forward and backward paths of the coils 10a, 10b, 11a, 11b is formed smaller than the widths of the poles 7a, 8a. The coils 10a, 10b, 11a, 11b are energized in the predetermined portion of a region that the rotary torque becomes 180 deg. or larger.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC motor that is equipped with at least two first and second phase coils and is driven to rotate by sequentially switching and energizing these coils. It is particularly suitable for application to brushless DC motors.

Conventionally, common energization methods for brushless DC motors include 3-phase 1-phase energization, 2-phase bidirectional energization, and 4-phase 2-phase energization. Figure 1A shows the rotor L and stator 3-phase coil L of a conventional 3-phase 2-pole brushless DC motor with 3-phase 1-phase energization system.
, , L, , and L3. FIG. Further, FIG. 1B is a waveform diagram showing the switching state of energization of each coil L1, L2, and L3. Further, FIG. 1C is a graph showing the torque generated in the rotor 1 by switching the energization of each coil. In addition, in FIG. 1A, in order to simplify the explanation, it is assumed that the permanent magnet Loco 1 is fixed and the coils L, , L2, L:l move relative to the mouth 1. .

Further, the rotor 1 and the coils Ll', Lz, and L3 are each shown expanded in a straight line.

In FIG. 1A, a sinusoidal magnetic field is formed by the alternating NS permanent magnets of the rotor 1. Each coil L
+, Lz, and L3 are each wound over approximately 180' electrical angle (ie, the width of one N or S permanent magnet). And these coils Ll, Lt,,L
, are arranged with a phase difference of 120 degrees in electrical angle.

Now, when the front end of coil L is at position θ1 (time t
, ), energization of this coil LI is started as shown in FIG. 1B. Note that the front end of the coil LL is, for example, the front end of the coil L.
1. When current is passed in the direction shown in Figure 1A, the forward path portion (or return path portion) of the coil generates torque in the positive direction on the motor rotor due to the magnetic flux of the N pole (or S pole). 6. +LT: I, I5. ka48
o7゜yo3yo1□0. .

The energization is continued until the rotation reaches the position θ2 (time tz). Therefore, as shown in FIG. 1C, from 1 to t2
Torque is generated by the current in the coil and the magnetic flux of the rotor 1.

When the front end of the coil L reaches the position θ2 (time tz), the current to the coil L1 is cut off, as shown in FIG. 1B. At this time, the front end of the coil L2 reaches the position θ1, and energization of the coil L2 is started from this time t2. The coil L2 is energized until the coil L2 rotates by 120 degrees in electrical angle and its front end reaches the position θ2 (time ts). As a result, the current in the coil 2 and the magnetic field of the rotor 1 cause t!, as shown in FIG. 1C. Torque is generated between t and t.

And coil, similarly for time t, to t4
Electricity is applied until this point, and torque is generated during this time.

In this way, between time points t1 and t4, each coil L1,
Lz and L3 are rotated by 360 degrees in electrical angle, and during this period, the energization of each coil is switched by 120 degrees in electrical angle to generate the positive torque shown in FIG. 1C.

Note that the rear ends of the coils LI, L2, and L are interlinked with S-pole magnetic flux during the respective energization periods, and the return path portion (or outbound portion) of the coils flowing through this rear end portion.
The current generates a torque in the same direction as the rotational torque at the front end of the coil.

In this way, in the case of a brushless morph with 3-phase 1-phase energization, it is necessary to switch the current three times within each 360° electrical interval. Therefore, three position detection elements are required to detect the rotation angle of the rotor 1.

That is, as shown in FIG. 1A, each coil LISLmL,
Three position detection elements are required to detect the timing at which the front end of the front end passes through the sections from θ to θ2, respectively. In this case, each of the three position detection elements has three
Since they have a relative positional relationship with each other in relation to the phase coils, the pin and
The notches must be adjusted, which increases the number of assembly steps. It is also possible to make a module by adjusting these position detection elements by 1 in advance and storing them in one pan cage, but in this case, one module can only be used for one type of brushless morph with the same Rogue diameter. There are drawbacks.

Further, three switch circuits (switching transistors) for three phases are required for current switching. Further, although not explained in detail, in the case of 4-phase 2-phase current flow, two position detection elements are required, and it is necessary to perform four same current switches in an interval of 360" electrical angle. In addition, in the case of two-phase bidirectional energization, two position detection elements are required, and the electrical angle 360
Current switching is required four times in the range of . In this case, eight switch circuits are required to supply current in both positive and negative directions.

Furthermore, if we consider a conventional two-phase, one-phase current type brushless morph in which the current is switched twice in an electrical angle section of 360°, in this case as well, the first
A sinusoidal magnetic field similar to that shown in Fig. A is formed by the rotor 1. Also, coiled, and Lz are each 18 in electrical angle.
It is wound with a winding angle of 0°. Also, this coil L+ and Lz
are arranged with a phase difference of 180 electrical degrees.

When the front end of the coil L1 is at the position θ1 (time t), current is started to flow through the coil L1 as shown in FIG. 2B. And the coil L1 is approximately 180 in electrical angle.
When the front end reaches the position θ2 (time tz) after rotating by 0.0°, the current supply is cut off. Next, at this time t2,
Its front end is θ.

The coil L2 that has reached the position is energized. Then, the coil 2 is energized until it rotates 180 degrees in electrical angle and its front end reaches the position 02 (time t3). Then coil in the same way.

and L2 are alternately switched and energized every 180 electrical degrees.

In this case, the switch signal for coiling and energizing 2 is as follows:
Since it can be formed from the inverted signal of the switch signal that energizes the coil L1, only one rotational position detector is required. Further, it is sufficient to have two switch circuits for current switching.

However, in this case, a torque as shown in Fig. 2C is generated.As is clear from Fig. 2C, in this case, at the electrical angle positions of 0° and 180°, the coil L,
, L2, no torque is generated because the magnetic field at this position is almost zero. Therefore, if the rotor 1 stops at these positions, the motor will not be started. Further, even if the rotor 1 stops near these electrical angles of 0° and 180°, the motor will not be started if there is a load on the motor. Therefore, it has conventionally been common knowledge that such a brushless motor cannot be realized unless some kind of starting torque generating means is provided. Moreover, even if a starting torque generating means is provided, as shown in FIG.

It was thought that Sopul would be quite large.

The inventor of the present invention has succeeded in breaking through the strong preconceptions described above by configuring the device as follows.

That is, the present invention comprises at least two first and second phase coils and at least two pole first and second magnetic flux generating means, and is rotationally driven by sequentially switching and energizing these coils. In the DC motor, the magnetic flux distortion means for distorting the density of the magnetic flux interlinked with the first and second coils is connected to the main pole N of the first and second magnetic flux generating means.
and the main pole S, and the angle formed by the center of the outward path portion and the center of the return path portion involved in torque generation of each of the first and second phase coils. The width of the main pole N or S is made smaller than the width of the main pole N or S, so that the composite rotational torque in a predetermined direction generated by the current flowing through the outgoing path portion and the returning path portion of each of the coils is 180° or more in electrical angle. The rotational torque is 1.
A current switching means is provided to sequentially switch the energization of the coils of each phase so that the respective coils are energized in a predetermined portion within a region of 80 degrees or more.

With this configuration, there is no part where the rotational torque is zero over 360 degrees in electrical angle, that is, there is no dead center of the rotor. Therefore, even when carrying out two-phase one-phase energization, for example, a special starting torque is required. This eliminates the need to provide a generating means.

Note that in the above description, the center of the outgoing path portion and the incoming path portion refers to the geometric average position of the plurality of conductors forming each of the outgoing path portion and the incoming path portion.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is an axial longitudinal cross-sectional view showing a first embodiment in which the present invention is applied to a two-phase, two-pole brushless DC motor of an outer rotor type and a two-phase, one-phase energization system. 4 is a sectional view taken along the line IV--IV in FIG. 3.

As shown in FIG. 3, a shaft support 3 having a cylindrical portion is fixed to one side of the side plate 2 having a substantially triangular shape. A bearing 4 is fitted in the center of the side plate 2, and a bearing 5 is fitted in the tip of the shaft support 3. A motor rotation shaft 6 is inserted through these bearings 4.5.

As shown in FIG. 3, one end of this motor rotating shaft 6 projects outward from the side plate 4 and is used, for example, to drive a head drum of a VTR. A cup-shaped rotor 1 constituting a rotor yoke is screwed to the other end of the rotating shaft 6. As shown in FIG.
A pair of permanent magnets 7a, 7b with a north pole (N pole) and a pair of permanent magnets 8a, 8b with a main pole (N pole) and a complementary pole (S pole) are attached, respectively. The main pole permanent magnets 7a and 7b each extend at a position angle of, for example, approximately 140 degrees with respect to the motor axis. Note that the position angle is a geometric angle between two points on the rotor or stator with respect to the motor shaft, and the electrical angle is the position angle multiplied by the number of pole pairs of the motor. However, in the following explanation, the electrical angle is calculated without including the permanent magnets 7b and 8b of the commutating poles in the number of pole pairs of the motor. Further, the permanent magnets 7b and 8b of the commutating poles each have a position angle of approximately 40 degrees, for example. The permanent magnets 7a and 7b of the main pole and the counter pole form a pair to form an electrical angle of 180°, and the permanent magnets 8a and 8b of the main pole and the counter pole form a pair to form an electrical angle of 180°. It consists of electrical angles.

''' Furthermore, the respective permanent magnets 7a, 7b, 8a,
8b are each magnetized in the thickness direction so that their inner surfaces form the magnetic poles shown in FIG. Further, a ring-shaped permanent magnet 18 for detecting the rotational phase of the rotor 1 is fixed to the end face of these permanent magnets in the axial direction of the motor, as shown by the dotted line in FIG. This permanent magnet 18 is magnetized in the axial direction of the motor, that is, in the thickness direction of the magnet, so that its N and S poles are symmetrical in position angle by 180 degrees.

A cylindrical stator core 9 is fixed to the outer periphery of the shaft support 3. On the surface of this identifier core 9, A-phase and B-phase stator coils 10 and 11 are arranged almost symmetrically with a phase difference of 180'' as shown in FIG. The coil 11 is wound so that the opening angle (winding pitch) between the outward path 10a and the return path 10b is approximately 120°, and the coil 11 is also wound such that the opening angle between the outward path 11a and the return path 11b is approximately 120°. The outer circumferential surfaces of these coils 10.11 are connected to the inner circumferential surfaces of the permanent magnets 7a, 7b, 8a, and 8b with a minimum allowable gap left in the radial direction. facing.

The end of the shaft support 3 on the side plate 2 side is formed into a ring shape and is fixed to the side plate 2. In the vicinity of this ring-shaped portion, the phase side plate 2 has a circuit board 12 having a central opening.
is fixed via a ring-shaped attachment member 13 made of synthetic resin. This circuit board 12 includes a stator coil 10
．． Circuit element 1 constituting a drive circuit for exciting 11
4 is installed. A lead wire (not shown) of the coil 10.11 is connected to this drive circuit. Further, a position detection dice 15 such as a Hall element for detecting the rotational phase of the rotor 1 is attached to a predetermined portion of the circuit board 12 facing the rotation locus of the permanent magnet 18. The excitation current flowing through the coils 10 and 11 is sequentially switched based on the detection signal obtained from the position detection dice 15.

Next, the operation of the brushless DC motor shown in FIGS. 3 and 4 will be explained based on FIGS. 5A to 5E. Furthermore, the fifth
Figure A is a simplified diagram of Figure 4 for explaining the operating principle of the brushless morph shown in Figures 4 and 3, and Figure 5B is a diagram of the magnetic flux density (magnetic field) of the magnetic flux interlinking with each coil 1o, 11. Graphs, Figure 5c is a graph for explaining the composite torque generated by the A-phase coil 10, Figure 5D is a graph representing the torque generated in the rotor by switching the energization of each coil, and Figure 5E is a graph for explaining the combined torque generated by the A-phase coil 10. FIG. 3 is a waveform diagram showing current switching.

In FIG. 5A, the outgoing paths 10a and lla and the incoming paths Job and l of the A-phase and B-phase coils 10.11 shown in FIG.
Only one tree of the average central part of lb is shown. Regarding the positional relationship between the rotor 1 and the coils 10°11, the outgoing path 10a of the coil 10 is located between the main pole permanent magnets 7a and 8.
The state at the interface with a is shown. The magnetic flux from each magnet 7a, 7b, 8a, 8b passes from the north pole magnet to the identifier core 9, as shown by the dotted line in FIG.
It enters the pole magnet, passes through the yoke of rotor 1, and returns to the north pole magnet. In this case, the position θ of the outward path 10a of the coil IO. With the starting point (0°), permanent magnets 7a, 7b, 8a, 8b
The magnetic flux density Bg of the air gap between and the stator core 9 is expressed as:
The result will be as shown in Figure 5B. However, in FIG. 5B, only the density of the magnetic flux in the radial direction of the motor involved in torque generation is shown, and the direction from the magnet to the identifier core 9 is defined as the positive direction.

As shown in Figure 5A, 0°, 140°, 180.22
At the 0° position, the direction of the magnetic flux is reversed, and near this position, the magnetic flux in the radial direction of the motor, which is involved in torque generation and interlinks with the coil, is decreasing. and each magnet 7
The magnetic flux density increases as it approaches the center of each of a, 7b, and 8a18b. For this reason, the magnetic flux density Bg has a substantially sinusoidal distribution within the range of each permanent magnet, as shown in FIG. 5B. Further, in the range of 180 degrees in electrical angle, an asymmetrical distribution of magnetic flux is formed between the main pole permanent magnets 7a, 8a and the counter pole permanent magnets 7b, 8b. That is, in one region of the reversed portion of the north pole and the south pole of the main magnetic pole, the level of magnetic flux density is reduced at each part of the south pole and the north pole.

・'I3, A[O:+ 4 /L/ 10 c:M 5
AtM&:;Rt71ii1° current, that is, forward path 10a
It is assumed that a current flows from the back surface of the drawing toward the front surface, and a current flows from the front surface of the drawing toward the back surface in the return path 10b. When an external force is applied to the motor rotating shaft 6 to rotate the rotor 1 in the direction of the arrow F in FIG. The torque (reaction of the force acting on the current) is as shown by the solid line a in FIG. 5C, as can be easily considered based on Fleming's left-hand rule. That is, a torque T substantially similar to the magnetic flux density Bg shown in FIG. 5B is generated.

Next, regarding the return path tob of the coil 10, this return path 10
Assume that b is located at the same position as the outbound route 10a.

Then, since the direction of the current is opposite to that of the outgoing path 10a, a torque (dotted chain line b') generated by turning the solid line a in FIG. 5C about the X axis is generated. In reality, there is an angular difference of approximately 120° between the outward path 10a and the return path 10b, so the torque generated in the rotor 1 by the current in the return path tab is at point bi in FIG. 5C.
As shown in b, it is obtained by translating the dashed-dotted line 120 degrees to the right. Therefore, the outgoing path 10 of the A-phase coil 10
The resultant torque generated in the rotor 1 by a and the return path 10b is shown in Fig. 5C! It will look like A. That is, Habo 13
Torque in the positive direction (direction W in FIG. 5) is generated in a section spanning an electrical angle of 220° (180° or more) from 2° to 352°.

Therefore, a predetermined section within the electrical angle range of 220 degrees (for example, approximately θr shown in FIG. 5C) where torque in the positive direction occurs
1 in electrical angle from (150”) to θ y (330”)
In the 80° section S), if the A-phase coil 10 and the B-phase coil 11 are energized alternately by 180° electrical angle, the motor rotates in the W direction in FIG. 5A. In this case, the B-phase coil 11 is the A-phase coil lO
Since they are arranged almost symmetrically and have a phase difference of 180 degrees in electrical angle, the torque characteristics due to the B-phase coil 11 are almost the same as those shown in FIG. 5C. Therefore, if the current between the A-phase coil 10 and the B-phase coil 11 is switched every 180 degrees of electrical angle as shown in FIG. 5E, there will be a portion where the torque is zero over 360 degrees of electrical angle, as shown in FIG. 5D. torque characteristics can be obtained. Note that the timing of current switching between the A phase and the B phase does not have to be strictly divided into equal intervals of 180 degrees.

For example, the A phase may be energized at 190° and the B phase may be energized at 170°.

The rotational position of the rotor 1 for switching the current of the brushless morph in this embodiment is detected by one position detection element 15, as shown in FIG.

That is, by detecting the timing of the rotation angle θ1 to 02 of the rotor 1 in FIG. 5C, the current switching signal shown in FIG. 5E can be generated for the coil 10. Further, the coil 11 can be formed using an inverted signal of this position detection element. Such a position detection element may be, for example, a magnetically sensitive element such as a Hall element. Alternatively, a pair of light-emitting element and light-receiving element may be used, and a notch may be provided in a part of the rotation locus of the rotor, so that light is blocked from θ1 to 02, and light is transmitted from θ2 to 01. Good too.

Note that the position detecting element detects a predetermined point in a 360° electrical angle section, and a predetermined timing signal forming circuit is activated according to the output signal of the position detecting element to detect the current from θ to θ2. The switching timing may also be determined.

In the brushless morph of this embodiment, as shown by the dotted line in FIG.
is installed. This permanent magnet 18 is magnetized so that the north pole and the south pole are at a position angle of 180°. The boundary between N and S is approximately 150° and 33°.
It is at the 0° position.

FIG. 6A shows an example of a two-phase two-pole brushless smoke drive circuit of this embodiment. Moreover, FIG. 6B is a waveform diagram showing the output voltage of the position detection element of FIG. 6A. In FIG. 6A, the position detecting element 15 is, for example, a Hall element, and the output terminal A of this Hall element is connected to the permanent magnet 1 of the rotor 1.
The N and S poles of 8 generate an output voltage as shown in a of FIG. 6B, and the output terminal B generates an output voltage as shown in b (dotted line) of FIG. 6B. The output signal a of the position detection element 15 is supplied to the switching transistor 17a via the transistor 16a. and time 1 in Figure 6B.
．． This transistor 17a is turned on during the period from t2 to t2, and the coil 10 is energized.

In addition, the output signal of the position detection element 15 is the transistor 16.
The signal is supplied to the switching transistor 17b via the transistor 17b. The transistor 17b is turned on from time t1 to t2, and the coil 11 is energized. As a result, as shown in FIG. 5E, the coils 10 and 11 are alternately energized by approximately 180 degrees in electrical angle.

If another magnetic sensing element or photocoupler is used, the output signals of these detection elements are used to energize one phase (for example, coil 10), and the energization of other phases (for example, coil 11) is determined by the output of the detection element. A signal obtained by inverting the signal may be used.

In the embodiment shown in FIGS. 3 to 6 above, the angle of the permanent magnets 7a and 8a is 140°, and the angle of the permanent magnets 7b and 8b is 40°.
, the winding pitch of coil 10.11 (outward path 10a, lla
The opening angle between the return path 10b and the return path 10b and llb is set to 120', but these angles can be changed in various ways. In addition, by adjusting the direction of magnetization of each of the permanent magnets 7a, 7b, 8a, and 8b, the tips of the magnetic flux density graph shown in FIG. It is also possible.

The winding pitch (opening angle between the outward and return paths) of each of the coils 10 and 11 is 1. As in the above example, the main pole permanent magnet 7a
, 8a should be smaller than those in the magnetic poles. This makes it possible to reduce the dip in torque that occurs approximately at the center of the combined torque when the torques of the outward and return paths of the coil are combined, thereby reducing torque ripple.

Furthermore, the magnetization strength of each magnet 7a, 7b, 8a, 8b can be changed, for example, the permanent magnets 7b, 8b of the interpolation
The strength of the magnetic field caused by this may be made small as shown by the solid line a in FIG. In this case, the combined torque of the coils 1O and 11 is as shown by the solid line A in FIG. 7, and the torque ripple can be reduced more than in the case shown in FIG. 5C.

Next, FIGS. 8A to 8D show a second embodiment of the present invention, in which FIG. 8A is a cross-sectional view of a brushless morph similar to FIG. 4, and FIG. 8B is a cross-sectional view similar to FIG. 5B. The graph of magnetic flux density, FIG. 8C, is a graph similar to FIG. 5C showing the resultant torque produced by the A-phase coil, and FIG. 8D is a graph similar to FIG. 5D, showing the torque produced in the rotor of the brushless morph.

As shown in FIG. 8A, the south-pole and north-pole magnets 7.8 each extend approximately 140 degrees relative to the motor axis. and the permanent magnet 7b of the commutating pole in FIGS. 4 and 5A.
, the 80° portion corresponding to 8b is the gap portion 2 without a magnet.
It is 0. Therefore, in this gap portion 20, the magnetic flux in the radial direction (from the rotor 1 to the stator core 9 or the opposite direction) that is involved in the rotational torque of the rotor 1 is eliminated. Therefore, the density Bg of the magnetic flux interlinking with the coil 10.1] is as shown in Figure 8B.
0''), a region where the magnetic flux density is approximately zero and flat occurs.

In Figure 8A, the A-phase and B-phase coils 10.11
The winding pitch of each is approximately 100 degrees in electrical angle. Therefore, in the same way as in FIG. 5C, the forward path 1 of the A-phase coil 10 is
The torque generated in the rotor 1 by the current 0a and the interlinkage magnetic flux of this coil is as shown by the solid line a in FIG. 8C. Further, the torque generated by the current in the return path 10b of the coil 10 is as indicated by the dotted line in FIG. 8C. And this outward journey 10
The resultant torque generated by a and the return path 10b is as shown by a solid line A, and therefore, a torque in the positive direction is generated by the current of the A-phase coil IO in an area extending over 180 degrees in electrical angle. Moreover, the B-phase coil 11 is symmetrical with the A-phase (180
8), the torque shown in FIG. 8D can be obtained by sequentially switching the energization between the A phase and the B phase by approximately 180 degrees in electrical angle. According to this embodiment, as is clear from FIG. 8D, the conventional 7.
j 3-phase 1-phase energization system f7)) 7L, 7 characteristics 0 Fig. 10) The torque clip can be made even smaller.

Next, FIGS. 9A, 9B, 10A, and 10B show a modification of the second embodiment described above. 9th
In FIG. 8A, the magnet 7.8 is extended to the gap 20 in FIG. 8A, and the portion of the magnet 7.8 corresponding to the gap 20 is thinned to form a recess 21. In this case as well, the recess 2
In the part No. 1, the magnetic flux involved in torque generation is not completely zero, but it is decreasing. Therefore, coil 10
．． The density Bg of the magnetic flux interlinking with 11 is as shown in FIG. 9B, and similarly to FIG. 8C, a positive torque over 180° in electrical angle is generated. Note that the gap portion 2 in Figure 8A
The recesses 21 in FIGS. 0 and 9A may be filled with a non-magnetic material having a small relative magnetic susceptibility.

Figures 10A and 10B show the cases of 4-pole and 6-pole brushless morphs, respectively, and 10AIQ has 4-pole magnets 7A, 7B, 8A, 8B, the first phase coil IOA,
IOB and second phase coils 11A and IIB are provided. Also, in Fig. 10A, six-pole magnets 7A, 7B,
7C, 8A, 8B, 8C and the first phase coil IOA,
IOB.

10C and second phase coil 11A, t IB, ilC
and is provided. In the case of FIG. 8A, since there is a gap in a part of the magnet of the rotor 1, a problem arises in that the rotation of the rotor 1 becomes unbalanced. However, when using 4 or 6 poles as shown in Figure 10A or 10B,
Void portion 20a, 20b or 20a, 20b, 20c
can be arranged approximately symmetrically with respect to the axis, so that the moment of the rotor caused by the torque can be made uniform.

FIGS. 11A and 11B show a third embodiment of the present invention. As shown in FIG. ttA, the permanent magnets 7.8 of this embodiment are attached over 180 degrees in electrical angle. A notch 22 having a predetermined angle (for example, 80°) is formed in the rotor 1 at one boundary with the magnet 7.8. For this reason, a portion of the magnetic path is missing at the notch 22. Therefore, the density of the magnetic flux acting on the coils 10, II decreases in the portion corresponding to the notch 22, as shown in FIG. 11B. Therefore, as in FIG. 8C, a torque in the positive direction extending over 180 degrees in electrical angle is generated. Note that notch 2 in Figure 11A
2 may be filled with a non-magnetic material.

FIGS. 12A and 12B show a fourth embodiment of the present invention. As shown in FIG. 12A, each electrical angle 18
A ferromagnetic shield plate 23 having a predetermined angle is attached to the inner surface facing the stator core 9 at one boundary portion of the permanent magnet 7.8 extending over 0°. In this case, the magnetic flux generated from the magnet 7.8 in the region of this shield plate 23 is transmitted to the shield plate 23 as shown by the dotted line in FIG. 12A.
Since it is short-circuited at 3, there is no leakage to the outside. That is, the gap between the shield plate 23 and the stator core 9 is magnetically shielded, and almost no magnetic flux exists. Therefore, the magnetic flux density Bg becomes almost zero in the region where the shield plate 23 exists, as shown in FIG. 12B. Therefore, it is possible to generate torque in the positive direction over an electrical angle of 180° or more in the same manner as shown in FIG. 8C.

FIGS. 13A and 13B show a fifth embodiment of the present invention. In FIG. 13A, a yoke 2 formed of a ferromagnetic material (for example, iron) is shown in the air gap 20 of FIG. 8A.
It has a structure filled with 4. In this case, yoke 2
In the portion 4, a magnetic path shown by the dotted line in FIG. 13A is formed. Therefore, as shown in Figure 13B, the magnetic flux density B
g becomes a curve almost similar to that shown in FIG. 5B. That is, almost the same effect as in the case where the commutating magnets 7a and 7b shown in FIG. 5A are provided can be obtained. As a result, it is possible to generate a positive torque of 180 degrees or more in electrical angle, similar to that shown in FIG. 5C.

Next, FIGS. 14A and 14B show a sixth embodiment of the present invention. In FIG. 14A, four interpolated permanent magnets 7b, 7c and 8b, 8c are provided with north and south poles alternately. Therefore, in the graph of the magnetic flux density Bg acting on the coils 10 and 11, as shown in FIG. 14B, irregularities corresponding to these commutating poles occur around an electrical angle of 180°. Therefore, even with this structure, it is possible to generate a positive torque of 180 degrees or more in electrical angle. Furthermore, it is also possible to provide a larger number of commutating poles.

Further, in FIG. 14A, a structure in which the permanent magnet 7C18c of the commutating pole is not provided, and that part is filled with a gap or a non-magnetic material is also possible. In this case, the magnetic flux density Bg at that portion becomes as shown by the dotted line in FIG. 14B, and a torque in the positive direction of 180 degrees or more in electrical angle can be generated. Also, when the magnet 7C18C is filled with a ferromagnetic material, a graph of magnetic flux density almost similar to the solid line in FIG. 14B is obtained.

Note that in the structure of the fifth Arg4, the magnet 7 in FIG. 14A
The notch 22 shown in FIG. 11A or the shield plate 23 shown in FIG. 12A may be provided in the regions corresponding to 8c and 8c. In this case, a graph of magnetic flux density almost similar to the dotted line in FIG. 14B is obtained.

Next, FIGS. 15A and 15B show a seventh embodiment of the present invention. In FIG. 15A, an anisotropic magnet 25 integrally formed in a cylindrical shape is used as a magnet attached to the rotor 1, and is magnetized into four poles as shown in FIG. 15A. Assuming that the magnetic domains are aligned in the downward direction H as shown by the vertical line in Figure 15A, in the magnetic flux decreases significantly. Therefore, by using such an anisotropic magnet 25, it is possible to generate a forward torque of 180 degrees or more in electrical angle by the current in one coil.

Note that the configuration shown in FIG. 15A can be applied only to a two-phase, four-pole brushless morph. Further, even if an anisotropic magnet 25 whose anisotropy direction is radial is used, a distribution of magnetic flux density Bg similar to that shown in FIG. 15B can be formed by changing the strength of magnetization.

To summarize the effects obtained by the two-phase, one-phase energizing type brushless DC motor according to the above-described embodiment, it is possible to eliminate the portion where the rotational torque is zero over 360" in electrical angle, that is, the dead center of the rotor. In addition, the current of the coils of each phase can be switched using one position detection element, and rotational torque can be generated by using only two switch circuits (switching transistors) for switching the current, so it is possible to Compared to a brushless morph drive circuit, the number of circuit elements can be greatly reduced.As a result, the cost of the drive circuit can be reduced, reliability can be improved because there are no circuit elements, and the drive circuit can be made smaller. be able to.

In particular, since the structure of the drive circuit becomes very simple, it is easy to house the drive circuit including the position detection element and the switching transistor in one package and integrate it into an IC. Furthermore, since only one position detecting element is required, it is necessary to adjust the positional relationship between each phase of the coil and the relative positional relationship between each element, unlike conventional brushless morphs that use multiple position detecting elements. There is no. Therefore, the position of the position detection element can be easily adjusted, and the number of assembly steps can be reduced.

In addition, since there is only one position detection element, there is no need to use a module with multiple position detection elements in one package as in the past, and the diameter of the rotor can be the same for various brushless morphs. position detection elements can be used, and parts can be easily standardized.

Although the present invention has been described above based on the embodiments thereof, various modifications can be made to the present invention based on the technical idea thereof.

For example, in the embodiment described above, an outer rotor type brushless smoke was explained, but the present invention can also be applied to an inner rotor type brushless morph. Further, the number of poles of the rotor 1 may be increased. The present invention is also applicable to DC brush motors. Furthermore, the present invention is also applicable to an axial air gap type motor in which a stator coil and a low-grade permanent magnet face each other in the axial direction of the motor.

Further, in the above embodiment, the angle α formed by the forward path portion and the return path portion of each of the A-phase and B-phase coils is 180 in electrical angle.
If the barrel is made so that the temperature is less than ° = '1,
The central angle of the portion along the circumferential direction of the motor (hereinafter referred to as the circumferential portion) connecting the outward path portion and the return path portion of each coil was set to be α. However, if the position angle of α is α′, then the angle of the circumferential portion is α′
The supplementary angle β (β is the position angle, α′+β=360@) may be used. For example, in the case of a two-phase, two-pole system, as shown in FIG. 16A, the angle α formed by the forward and backward portions of the A-phase coil 10 (solid line) and the B-phase coil 11 (dotted chain line) is 1.
206 (α'=120'), the central angle of each circumferential portion of the A-phase and B-phase coils is 360'-120°=2
40". In this case, the A phase and B phase
The phase coils 1O111 are wound with a phase difference of 180@.

Also, the angle α ('r!1 air angle) formed by the outgoing and returning portions of the A-phase and B-phase coils is 360° x m + α (
m: positive integer). In this case, for example, the 8th C
Since the torque curve due to the outgoing and returning portions of the A-phase coil indicated by the solid line a or point Hb in the figure is relatively shifted by 360'Xm, the resultant torque generated by the outward and returning portions of the A-phase coil is It is similar to the solid line A in Figure 8C, and it is possible to generate torque in the positive direction in an area extending over 180" in electrical angle. In this case, if the number of poles of the motor is n, each of the A-phase and B-phase coils The angle formed by the forward path portion and the return path portion is the circumferential direction portion of the A-phase and B-phase square coils, as described above.

Figure 16B shows the case of 2-phase 4-pole when α=100'', in which the A-phase coils IOA, 10B (l[) and the B-phase coils IIA, IIB (dotted chain lines) are 130° (260 ), and the A-phase coil I shown by the solid line
OA and JOB are 3 electrical degrees apart from each other as shown in Figure 16R.
The A-phase and B-phase coils IOA, IIA, IOB, and 11B are arranged with a phase difference of 60"(180" in phase angle), and the coils IOA, IIA, IOB, and 11B are arranged at a position of 180' in electrical angle (900" in position angle). They are arranged in phase difference.

The present invention provides the first and second phase coils such that the composite rotational torque generated by the forward current and return current of the first and second phase coils is 180'' or more in electrical angle.
A magnetic flux distortion means for distorting the density of the magnetic flux interlinking with the coil is provided on one side of the reversal region of the main pole NS of the magnetic flux generation means, and the angle formed by the outward path portion and the return path portion of the coil is set to be smaller than the width of the main pole. The coils are made smaller, and the energization that is sequentially applied to each coil is performed in a predetermined portion within a region where the rotational torque L is 180' or more. Therefore, it is possible to eliminate the portion where the rotational torque is zero over 360" in electrical angle, that is, the dead center of the rotor. Therefore, according to the present invention, energization switching can be performed using only one position detection element. Even when two-phase and one-phase energization is performed, there is no need to provide a special starting torque generating means.

In addition, by reducing the opening angle between the outgoing and returning paths of the coil with respect to the magnetic pole of the main pole, the drop in torque that occurs approximately in the middle of the composite torque due to the sum of the outgoing and returning currents is reduced, and the torque is increased. A two-phase DC motor with less ripple can be obtained.

[Brief explanation of drawings]

Figure 1A shows the three-phase coils L1, Lx, and Lx of the conventional three-phase and one-phase brushless DC motor.
Figure 1B is an explanatory diagram showing the relative positional relationship with coils L+ and L! , L3, and FIG. 1C is a graph showing the torque generated in the rotor by switching the energization of each coil. Figure 2A is an explanatory diagram showing the relative positional relationship between the rotor of a conventional two-phase, one-phase brushless DC motor and the two-phase coils L, , L2 of the stationary coil 7,
Waveform diagram showing switching state of energization of Shiri, L, 2nd waveform diagram
Figure C is a graph showing the torque generated in the rotor by switching the energization of each coil. FIG. 3 is an axial longitudinal cross-sectional view showing a first embodiment in which the present invention is applied to a two-phase, two-pole brushless DC motor with an outer rotor type and a two-phase, one-phase energization method. IV-
5A is a simplified diagram of FIG. 4 to explain the operating principle of the brushless DC motor shown in FIGS. 3 and 4, and FIG. 5B is the magnetic flux density of the magnetic flux interlinking with each coil. Figure 5C is a graph for explaining the composite torque generated by the A-phase coil, Figure 5D is a graph representing the torque generated between the two coils by switching the current of each coil of a brushless DC motor, and Figure 5E is a graph for explaining the composite torque generated by the A-phase coil. are A phase and B
A waveform diagram showing phase current switching, FIG. 6A is a circuit diagram showing an example of a drive circuit for a two-phase, two-pole brushless DC motor of the present invention, and FIG. 6B is a waveform showing the output voltage of the position detection element in FIG. 6A. 7 is a graph similar to FIG. 5C when the strength of magnetization of the permanent magnet of the interpole is changed. 8A to 8D show a second embodiment of the present invention, FIG. 8A is a sectional view of a brushless DC motor similar to that in FIG. 4, and FIG. 8B is a graph of magnetic flux density similar to that in FIG. 5B. , 8th
Fig. C is a graph similar to Fig. 5C showing the composite torque generated by the A-phase coil, and Fig. 8D is a graph similar to Fig. 5D showing the torque generated in the rotor of the brushless DC motor. Figures 9A, 9B, 10A and 10B are
Fig. 9A is a cross-sectional view similar to Fig. 8A, Fig. 9B is a graph of magnetic flux density, and Figs. 10A and 10B show a 4-pole and 6-pole brushless DC motor, respectively. FIG. 8A is a cross-sectional view similar to FIG. 8A shown in FIG. 11A, 11B to 15A, and 15B show third to seventh embodiments of the present invention, and FIGS. 11A to 15
Figure A is a sectional view of a brushless DC motor similar to Figure 5A, and Figures 11B to 15B are Figures 11A to 15A, respectively.
FIG. 5B is a graph of magnetic flux density similar to the corresponding FIG. 5B; 16A and 16B are cross-sectional views similar to FIG. 8A showing an eighth embodiment of the present invention. In addition, in the symbols used in the drawings, 1.-----.--.---1 rotor'-7a,
7b, 8a, 8b - - - - - - - - - Permanent magnet 9 - - - - - - - Stator core 10, 1
1...Stator coil 15...---
−−・−・−・−Position detection element 20・−・−−−−
−−・・−・・−Gap part 2 t−−−−−−−1・
・−−−−−−−−1 recess 22・−−−−1・・−・−
--One・----It is completely lacking.

Claims (1)

[Claims] A direct current device comprising at least two first and second phase coils and at least two-pole first and second magnetic flux generating means, and rotationally driven by sequentially switching and energizing these coils. In the motor, the magnetic flux distortion means for distorting the density of magnetic flux interlinked with the first and second coils is arranged in an inversion region between the main poles N and S of the first and second magnetic flux generating means. The angle formed by the center of the outward path portion and the center of the return path portion, which are involved in torque generation of each of the first and second phase coils, is smaller than the width of the main pole N or S. As a result, the composite rotational torque in a predetermined direction generated by the current flowing through the outward path portion and the return path portion of each of the coils is configured to be 180° or more in electrical angle, and the rotational torque is 180° or more. A DC motor provided with a current switching means for sequentially switching the energization of the coils of each phase so that the respective coils are energized in a predetermined portion within the region.