JPH0767264B2 - Brushless motor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a small brushless DC motor.

As is well known, conventional brushless motors have a coil on the stator side and a magnet on the rotor side, and the rotational position of the magnet is detected by a detection element such as a Hall element. The current flowing through the coil is controlled.

Problems to be Solved by the Invention Since the conventional brushless motor is configured as described above, it has the following drawbacks.

(1) Since the heavy magnet rotates, the inertia is large.

(2) A magnet position detecting element is required.

(3) A drive circuit for switching the coil current according to the position of the magnet is required.

(4) Switching noise occurs when switching the coil current.

Means for Solving the Problems The present invention relates to a stator comprising at least a two-pole magnet and at least one first coil which is provided on a boundary between magnetic poles of the magnet and is supplied with an AC power source. A brushless motor was configured with a mover which is arranged at a predetermined distance from the magnet and faces the magnet, and which has at least two second coils each having a diode connected between both ends thereof.

Action Mutual induction action occurs between the first coil and the second coil, and the fact that the coupling coefficient of the two coils changes depending on the positional relationship between the two coils allows the magnet and the first coil to be separated. The mover including the second coil can be moved with respect to the provided stator.

Embodiment FIG. 1 and FIG. 2 show a first embodiment of the present invention.

In the figure, a stator 1 is composed of, for example, a ring-shaped magnet 2 magnetized to have 6 poles and, for example, three coils 3 ₁ , 3 ₂ and 3 ₃ . The coil 3 ₁ to 3 _3, when the rotor 4 described later is rotated in the arrow a direction, the magnetic poles of Magunetsuto 2 is placed on the boundary of transition to the S-pole from along connexion N pole in the direction of arrow a It is fixed. Lead wires led out from both ends of each of the coils 3 _{1 to} 3 ₃ are connected to an AC power source 6 via a variable resistor 5 for speed control. In this case the coil
3 _{1 to} 3 ₃ may be connected in parallel as shown, or may be connected in series.

The rotor 4 includes a coil fixing plate 8 made of a non-magnetic plate such as a disk-shaped plastic, and four coils 9 ₁ , 9 ₂ , 9 ₃ , 9 arranged on the coil fixing plate 8. _4, four diodes for connecting the ends of the coils 91 _to 93 ₄ 1
It is composed of 0 ₁ , 10 ₂ , 10 ₃ , and 10 ₄ and a rotary shaft 11. The coil fixing plate 8 and the coils 3 _{1 to} 3 ₃ are arranged via a predetermined gear d. The Above the coil 9 _to 93 _4, provided in a state in which the magnetic plate 7 made of iron plate or the like is fixed to the coil 9 _to 93 ₄ via a predetermined Giyatsupu l, forms a magnetic path of Magunetsuto 2 is doing.

Next, FIGS. 3 and 4 schematically show the operating principle of the motor. In these figures, reference numeral 3 designates the coils 3 _{1 to} 3 ₃ ,
Reference numeral 9 represents the coils 9 _{1 to} 9 ₄ , respectively. Similarly, reference numeral 10 in FIG. ₄ represents the diodes 10 ₁ to 10 ₄ .

Next, the AC power source 6 shown in FIG.
Although the current is supplied from the device, the reference numeral B ₂ shown in FIG. 3 indicates an alternating magnetic field generated by this current. Reference numeral B ₁ is a static magnetic field generated by the magnet 2.

By the way, when the coil 9 on the side of the rotor 4 occupies the position shown in FIG. 3A, the coil 9 is not in a position facing the coil 3 on the side of the stator 1 and is therefore affected by the alternating magnetic field B _2. There is no such thing. Therefore, no alternating pressure is induced in the coil 9.

Next, as shown in FIG. 3B, when the coil 9 of the rotor 4 faces the coil 3 of the stator 1, the alternating magnetic field B ₂ generated due to the alternating current flowing through the coil 3 is linked to the coil 9, As a result, an alternating voltage is induced in the coil 9.

In this case, since the diode 10 is inserted between both ends of the coil 9 as described above, even if the alternating voltage is generated in the coil 9, the current I flows only in one direction as shown in FIG. ).

As a result of the current I and the magnetic field B ₁ generated by the magnet 2 interlinking, a force F acts on the coil 9 in the direction of the arrow as shown in FIG. As a result, the coil 9 moves in the arrow direction. Then, when it moves to the position of FIG. 3C, the coil 9 stops receiving the magnetic field B ₂ again and stops.

That is, to summarize the above, the coil 3 arranged on the side of the stator 1 is a means necessary for transmitting electric power to the coil 9 on the side of the rotor 4, and the magnet 2 is connected to the coil. It is a means necessary to give the acting force F.

However because the force F is generated only when the coil 9 is located above the coil 3, a plurality of coil 3 ₁ As Figure 1
~ 3 ₃ and coils 9 _{1 to} 9 ₄ are provided so that at least _one coil of coils 9 _{1 to} 9 _{4 is} always above at least one coil of coils 3 _{1 to} 3 _3. By arranging
A rotating force can be obtained by continuously generating a force.
In order to obtain a continuous rotational force, the minimum number of coils on the stator side is one, and the number of coils on the rotor side is required to be two or more. The magnet 2 used is one magnetized with two or more poles.

FIG. 5 shows a second embodiment of the present invention.

In the brushless motor according to the first embodiment described above, the rotor 4 rotates only in the direction of arrow a in FIG. In this embodiment, it is possible to rotate in the opposite direction to the a direction together with the a direction. The stator 1 is newly provided with coils 3 ₄ , 3 ₅ , and 3 ₆ together with the coils 3 _{1 to} 3 ₃ . These coils 3 _{4 to} 3 ₆ have magnetic poles indicated by arrows a between the coils 3 _{1 to} 3 _3.
It is placed on the boundary (see FIG. 1) that changes from the S pole to the N pole along the direction. These coils 3 _{4-3 6} is connected is connected in parallel or in series with each other are not shown to the AC power supply 6. The structure of the rotor 4 is exactly the same as that shown in FIG.

Next Stated using the FIG. 3 in the case of the coil 3 _{4-3 6,} is because the position of the N and S poles in the figure interchanged in this case, the direction of the magnetic field B ₁ is reverse As a result, the direction of the force F is opposite to that shown in the figure. Therefore, the coil 9 moves in the opposite direction. Incidentally, connected via the switch to the forward rotation coil 3 ₁ to 3 ₃ and the reverse rotation coil 3 _{4-3 6} to a common AC power supply 6, configured to switch the switch in response to the direction of rotation be able to. Further, in order to rotate the rotor 4 in the opposite direction, the diodes 10 ₁ to 1 in FIG.
0 by changing the _fourth orientation, the direction of the current I may be made in the reverse direction.

According to the motors of the first and second embodiments described above, the following operational effects can be obtained.

(1) Since no magnet is used for the rotating body 4, the rotating body becomes light in weight, and thus a motor with low inertia and good response can be obtained.

(2) No rotor position detector is required.

(3) Since it can be driven simply by connecting an AC power source, a drive circuit is not required. Therefore, in addition to the above (2), a small and inexpensive motor can be obtained.

(4) No switching noise is generated.

(5) If the PWM signal is used as the alternating current, the rotation of the motor can be controlled.

(6) Maximum efficiency can be obtained by selecting the frequency of the AC power supply as the resonance frequency of the coil.

FIG. 6 shows the third embodiment in principle, and is a case where the present invention is applied to a linear motor for linearly moving the coil 9.

The magnet 2 is magnetized in a linear direction as shown in the figure, coils 3 ₁ and 3 ₂ are arranged on the boundary from the N pole to the S pole, and the AC power source 6 is connected. The coil 9 to which the diode 10 is connected is placed above the magnet 2. When the coil 9 as shown above the coil 3 _1, unidirectional current I flows force F to occur. The moving distance can be further extended by further increasing the number of coils on the moving body side and the stator side. A coil for reverse movement may be provided between the coils 3 _{1 and} 3 ₂ . Further, the magnet 2 may be formed in a cylindrical shape instead of a flat shape as shown in FIG.

EFFECTS OF THE INVENTION Since the mover using the second coil is lightweight, it is possible to obtain a motor having low inertia and good responsiveness.
Further, since a device for detecting the position of the mover is not required and the device can be driven simply by connecting an AC power source, a drive circuit is not required. Therefore, a small and inexpensive motor can be obtained. Further, no switching noise is generated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention, and FIG.
The drawings are side views, FIGS. 3 and 4 are principle views of operation, FIG. 5 is a perspective view of a stator showing a second embodiment of the present invention, and FIG. 6 is a principle view showing the third embodiment. FIG. In the reference numerals used in the drawings, 1 ... stator 2 ... magnet 3 _{1 to} 3 ₆ ... coil (first coil) 4 ... rotor (mover) 9 _{1 to} 9 ₄ ... coil ( Second coil) 10 ₁ to 10 ₄ It is a diode.

Claims (1)

[Claims] 1. A stator comprising a magnet having at least two poles and at least one first coil provided on a boundary between magnetic poles of the magnet and supplied with AC power, and a predetermined distance from the magnet. 2. A brushless motor, characterized in that it comprises a mover composed of at least two second coils arranged opposite to the magnet and having a diode connected between both ends thereof.