JPS6387145A - Coil for dc motor - Google Patents

Abstract

PURPOSE:To reduce the fluctuation of torque, by making a winding width to the internal side larger than a winding width to the external side, based on virtual lines at both the ends of a theoretical electrical open angle pi at each unit coil pole of a stator coil. CONSTITUTION:One side main-surface of a rotor magnet 1 having magnetic poles N and poles S which are magnetized alternately and uniformly in the circumferential direction is firmly fitted on a rotor plate 2, and the rotor plate 2 is firmly fitted on a rotary shaft 4 via a sleeve 3. In the meantime, a flattened coil 9 made of a unit coil 1A plane-set in the circumferential direction is set between the rotor magnet 1 and a confronted yoke 8, to be confronted with each other. The unit coil pole 1A is composed so that a winding width b to the internal side may be larger than a winding width (a)to the external side of the unit coil pole 1A at a working radius section 13, based on virtual lines 12 at both the ends of a theoretical electrical open angle pi at the unit coil pole according to the quantity of the magnetic poles, and is wound up so that a relation b/a = 2 may be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coil for a flat DC brushless motor.

(Prior Art) With the recent miniaturization of electronic devices, this type of small motor has various uses, and is used in rotating systems such as tape recorders and video cameras.

Furthermore, there is a demand for a motor that takes advantage of the small size feature and has less uneven rotation and less torque fluctuation. Further, preferably, by using a coil in which a patterned conductor is formed on one or both main surfaces of a flat substrate by etching, plating, etc., as the armature coil, the flat brushless structure can be further improved. motor can be provided.

In this type of DC motor, a stator (armature) coil is placed opposite a disc-shaped rotor magnet with multiple poles made by magnetizing N poles and 58I alternately and equally in the circumferential direction. . In each of these armature coils, unit coil poles are arranged in a plane on the circumference according to the number of phases, and the winding width of the coil poles is determined by the theoretical electrical opening angle of the unit coil poles corresponding to the number of magnetic poles P. With reference to the imaginary lines at both ends of the dowel, the outer winding width a and the inner winding width S of the windings of the unit coil poles in the operating radius are set to be equal to each other. The back electromotive pattern generated by the magnet is determined by the magnetic field pattern generated by the magnet, so a trapezoidal wave-like magnetic field pattern produces a trapezoidal wave-like back electromotive pattern, which in turn results in a trapezoidal wave-like torque pattern.

Therefore, in order to obtain a motor with less torque fluctuation, it is necessary to take measures such that the magnetic field pattern generated by the magnet becomes sinusoidal in the coil portion. For this purpose, for example, the coil is divided into multiple phases, and the current flowing through each phase coil of the multiple phase coils is controlled in a predetermined waveform. In addition,
Torque fluctuations were reduced by appropriately combining the torques generated by each phase coil.

For example, a two-phase coil may be driven in a sine wave with an electrical angle shift of π/2, and a three-phase coil may be driven in a sine wave with an electrical angle shift of π/3 or 2/3π. In this case, the magnetic field pattern needs to be sinusoidal, and in order to make the 6n field pattern sinusoidal, it is necessary to perform irregular magnetization such as making the magnet into a star shape or narrowing the magnetization width. Alternatively, attempts were made to widen the distance between the magnet and the coil.

[Problem that the invention seeks to solve]

However, as mentioned above, if the magnet is magnetized irregularly,
Alternatively, widening the distance between the magnet and the coil not only makes it impossible to fully utilize the energy of the magnet, but also has the drawback of making it difficult to make the device smaller and thinner.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and provide a coil for a DC brushless motor that is flat, has high torque, and has extremely low torque fluctuations while fully utilizing the energy of the magnet. It is in.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the present invention, in order to make the back electromotive pattern generated by the coil sinusoidal, the magnetization is made irregular as in the past, and the magnet The unit coil poles are arranged on a plane on the circumference according to the number of phases without taking measures such as increasing the distance between the coil and the coil, and the winding width of the winding in each unit coil pole is equal to the number of magnetic poles P. Based on the imaginary lines at both ends of the theoretical electrical opening angle π of the unit coil pole corresponding to the magnetic pole of , b/a is at least 1.2 or more, preferably 1.4 or more, so that the back electromotive pattern generated by the coil becomes sinusoidal.

[For production]

According to the present invention, the winding width of the winding at each unit coil pole of the stator coil is set to the outer side in the operating radius portion with reference to the imaginary line at both ends of the theoretical electrical opening angle π of the unit coil corresponding to the number of magnetic poles P. Since each inward winding width is not equal and the width of each inward winding is widened, even a trapezoidal magnetic field pattern produces a back emf pattern that is close to a sine wave, creating a sinusoidal magnetic field pattern. The same effect can be obtained.

Roughly speaking, the unit coil pole is divided into multiple phases, and the current flowing through the winding of the unit coil pole for each phase of these multiple phase unit coil poles is determined by the theoretical electrical open circuit of the unit coil pole corresponding to the number of magnetic poles P. By commutating at a timing corresponding to the angle π and, in addition, appropriately combining the torques generated by each unit coil pole, torque fluctuations can be extremely reduced. In this case, by making the current a sine wave, it is possible to further reduce torque fluctuations.

Furthermore, in the present invention, by increasing the winding width of the inward winding described above, the effective portion for torque generation increases, so that there is an effect of increasing the generated torque.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a DC brushless motor to which an embodiment of the DC brushless motor coil according to the present invention is applied.

Here, l is a rotor magnet having eight magnetic poles Is and IN, in which N poles and S poles are magnetized alternately and equally in the circumferential direction, as shown in FIG. This rotor magnet 1
One main surface of the rotor plate 2 is fixed to the rotor plate 2. This rotor plate 2 is fixed to a rotating shaft 4 via a sleeve 3. One end of this rotating shaft 4 is pivotally connected to a bearing 6 fixed to a center hole of a housing 5, and the other end is connected via a pivot bearing 7.
It is attracted to the opposing yoke 8 by the magnetic force of the rotor magnet l.

On the other main surface of the rotor magnet l, a flat coil 9 configured by six unit coils 9A arranged in a plane in the circumferential direction as shown in FIG. The rotor magnet l is disposed opposite to the rotor magnet l with a predetermined distance therebetween.

As described above, a motor having a flat structure as shown in FIG. 1 is constructed.

FIG. 4(A) shows an example of the winding state of the winding in the unit coil pole of the conventional system, and is based on the virtual line 10 at both ends of the theoretical electrical opening angle π of the unit coil pole IB corresponding to the number of magnetic poles P. In this case, the outer winding width a of the unit coil ilB in the operating radius portion 11 is equal to the inner winding width a.

On the other hand, FIG. 4(B) shows an example of the winding state of the unit coil pole IA of the present invention, and shows lI! ! 8i Based on the virtual line 12 at both ends of the theoretical electrical opening angle π of the unit coil pole corresponding to the number P, the winding width inward from the outside winding width a of the unit coil pole IA in the operating radius portion 13 is determined. Broadly composed, b/a
= 2 wrapped.

Here, if the unit coil pole A is a winding in which a patterned conductor is formed on one or both main surfaces of a flat board using etching or plating, an effective wire that contributes to torque generation can be used. Since the length of the coil can be increased, the thickness of the coil can also be reduced.

The thickness of the unit coil pole IA is determined by effectively using the magnetic end of the magnet.
In order to realize thinning, it is effective to make the thickness 0.9 mm or less, preferably 0.7 mm or less.

Further, although it is possible to form the unit coil pole IA into a comb-wave pattern, a spiral pattern is preferable in order to efficiently arrange a multiphase pattern on the same plane.

Here, the thickness of the rotor magnet 1 is 1.5 mm.

The distance between the rotor magnet l and the opposing yoke 8 is 1.2 m.
m, and if a coil 9 with a thickness of 0.91 is placed at a distance of 0.3 mm1li from the rotor magnet 1, the coil 9
The magnetic field pattern at the mounting position is the fifth in the circumferential direction.
The result is similar to the trapezoidal wave shown in the figure.

Under this condition, the back electromotive pattern of the coil according to the conventional winding method shown in FIG. 4(8) becomes a trapezoidal waveform as shown in FIG. 6(A). When the coil of this winding method is divided into three phases and shifted by π/3 or 2π/3 in electrical angle and driven at the timing shown in Fig. 6(B), Fig. 6(C) shows curve 14. A torque pattern as shown was obtained. On the other hand, when such a coil was driven during glue timing in FIG. 6 ([1)], a torque pattern as shown by curve 15 in FIG. 6 (E) was obtained.

Under the same conditions, the back electromotive pattern of the coil according to the present invention shown in FIG. 4(B) becomes close to a sine wave as shown in FIG. 7(A). If this coil is divided into three phases and shifted in electrical angle by π/3 or 2π/3 and driven at the timing shown in Fig. 7(B), the torque as shown by curve 16 in Fig. 7(C) will be obtained. A pattern was obtained. On the other hand, when such a coil was driven at the timing shown in FIG. 7(D), a torque pattern as shown by curve 17 in FIG. 7(E) was obtained.

Here, the curve 14 in FIG. 6(C), the curve 16 in FIG. 7(C), the curve 15 in FIG. 6(E), and the curve 15 in FIG. 7(E)
Even when compared with the curve 17 in FIG. 7, it can be seen that the torque fluctuations in FIGS. 7(C) and 7(E) are smaller.

In other words, the unit coil poles are arranged in a plane on the circumference according to the number of phases, and the winding width of the unit coil pole is based on the imaginary line at both ends of the theoretical electrical opening angle π of the unit coil pole corresponding to the number of magnetic poles P. In the coil according to the present invention, the inward winding width is set to be wider than the outward winding width a at the operating radius.
Torque fluctuations can be extremely reduced.

Figure 8 shows unit coil poles arranged in a plane on the circumference according to the number of phases, and the operating radius section with reference to the virtual line at both ends of the ideal electrical opening angle π of the unit coil pole corresponding to the number P of 61 poles. It shows the torque fluctuation rate with respect to the ratio b/a of the outer winding width a and the inner winding width
) or when driving at the timing shown in FIG. 7(B), curve 19 is the result when driving at the timing shown in FIG. 6(D) or FIG. 7(D). As is clear from FIG. 8, when the ratio b/a of the inward winding width to the outward winding width a is 1.2 or more, the torque fluctuation rate increases based on the above-mentioned imaginary line. It can be seen that the torque fluctuation rate becomes small, particularly preferably when the value is 1.4 or more, the torque fluctuation rate becomes extremely small.

〔Effect of the invention〕

As is clear from the above, according to the present invention, the unit coil poles are arranged in a plane on the circumference according to the number of phases, and the winding width of the unit coil pole is the theoretical electric potential of the unit coil corresponding to the number of magnetic poles P. Using the imaginary lines at both ends of the opening angle π as a reference, the winding width inward from the imaginary line at the operating radius is wider than the winding width a toward the outside, and the unit coil poles are set according to multiple phases. Separate by
The current flowing through the windings of the unit coil poles for each phase of these multiple phase unit coil poles is commutated at a timing corresponding to the theoretical electrical opening angle π of the unit coil pole corresponding to the number of magnetic poles P, and in addition, By appropriately combining the torques generated by each unit coil pole, torque fluctuations are extremely reduced.

In this case, by making the current a sine wave, it is possible to further reduce torque fluctuations.

Furthermore, in the present invention, by increasing the winding width of the inward winding described above, the effective portion for torque generation increases, so that there is an effect of increasing the generated torque.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of a DC motor with a flat structure using an embodiment of the coil of the present invention, Fig. 2 is a plan view showing an example of the magnetization of the rotor magnet, and Fig. 3 is the FIG. 4 is a plan view showing one embodiment of the coil (
A) and (B) are explanatory diagrams of the coil winding states in the conventional example and the embodiment of the present invention, respectively. Fig. 5 is a magnetic field pattern diagram of the embodiment of the present invention. Fig. 6 (A)
, (B) and ([1) and (C) and (E) are respectively a back electromotive pattern diagram, a timing chart of coil energization, and a timing chart of coil energization when using the conventional coil shown in FIG. Torque pattern diagram, Figure 7 (A), (B) and (D
) and (C) and (E) are respectively shown in Figure 5 (8).
FIG. 8 is a back electromotive pattern diagram, a coil energization timing chart, and a torque pattern diagram when using the coil of the embodiment of the present invention shown in FIG. l... Rotor magnet, Is, IN... Magnetic pole, 2... Rotor plate, 3... Sleeve, 4... Rotating shaft, 5... Housing, 6... Bearing, 7... ... Pivot receiver, 8... Opposing yoke, 9... Flat coil, 9A, 9B... Unit coil, 10, 12... Virtual line of theoretical electrical opening angle π, 11, 13
... Operating radius portion, 14-17... Torque fluctuation curve, 18.19... Torque fluctuation rate curve. Cross-sectional view of motor Fig. 1 Fig. 2 Fig. 6 (B) IL Torque pattern diagram of A row Fig. 6 (C) IQ N timing + yard Fig. 6 (D) Torque pattern diagram of the A-row A row in the previous figure 6 (E)
) Out to the ward τπ ding 1 Ding in τ 2 shaku rotation row - , ne, 屓 5 go to gaffe beggar 9n torque pattern diagram Fig. 7 (E)

Claims (1)

[Claims] 1) Opposed to a disc-shaped rotor magnet having 2P magnetic poles (P is an integer of 2 or more) in which N and S poles are magnetized alternately and equally in the circumferential direction. , in a stator coil for a flat DC brushless motor in which unit coil poles of m (m is an integer of 2 or more) phases are arranged in a plane, the unit coil poles are arranged in a plane in the circumferential direction according to the number of phases, The winding width of the unit coil pole is set to the outside of the imaginary line of the unit coil pole in the operating radius portion, with reference to the imaginary line at both ends of the theoretical electrical opening angle π of the unit coil pole corresponding to the number of magnetic poles P. The winding width b of the inner winding is set to be wider than the winding width a of the winding, b
A coil for a flat DC brushless motor, characterized in that /a is determined to be at least 1.2 or more. 2) A DC motor coil according to claim 1, wherein the b/a is set to be 1.4 or more.