JPH0690536A - Brushless motor - Google Patents

Abstract

PURPOSE:To permit high-speed rotation and realize a miniaturized and high- output brushless motor by a method wherein intermediate terminals are provided in a stator constituted of 3n pieces of driving coils forming respective conductive phases while driving transistors are connected to the intermediate terminals. CONSTITUTION:Intermediate terminals are provided in driving coil group L1a-L3b of respective conductive phases consisting of U-phase, V-phase and W-phase while the intermediate terminals are connected to the collectors of driving transistors Q4, Q5, Q6 and current is conducted through both terminals of the driving coils L1a-L3b upon normal rotation. Upon high-speed rotation, the current is conducted through one side of the driving coils L1a-L3b and the intermediate terminals. According to this method, a brushless motor, capable of changing the torque characteristics of the motor, capable of effecting high- speed rotation, miniaturized and having a high output, can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-output and high-speed rotation brushless motor used as a drive source in the fields of information and sound.

[0002]

2. Description of the Related Art In recent years, brushless motors have come to be used more and more with the downsizing and thinning of products, and the demand for high-output type motors is also increasing with higher functionality.

FIG. 5 is a sectional view of a conventional brushless motor. Reference numeral 1 is a shaft, 2 is a rotor boss that is press-fitted and fixed to the shaft 1, 3 is a permanent magnet in which fan-shaped N and S poles are alternately magnetized, 4 is a rotor frame made of a magnetic material that fixes the permanent magnet 3, and 5 is a rotor frame. A sub-rotor yoke that forms a magnetic circuit with the permanent magnet 3 and that rotates integrally and faces each other;
6 is a metal, 7 is a thrust receiver, and 8 is a housing that rotatably supports the shaft 1. 19 is a stator,
The drive coil 19a is integrally molded.

As shown in FIG. 6, the drive coil 19a of the stator 19 has six coils L1a, L2a, L3a, L1b, L2b, and L3b, each having an angular pitch of 60 degrees, arranged adjacent to each other in a ring shape. A terminal 19c is formed outside the stator 19. FIG. 7 is a wiring diagram of the drive coil. When the drive coils L1a and L1b are connected in series, U
The phase is established and is connected to the terminal 19c1. The terminal 19c1 is connected to the collector of the drive transistor Q11.
Similarly, the drive coils L2a and L2b are connected in series to form a V phase and are connected to the terminal 19c2. Terminal 19c
2 is connected to the collector of the drive transistor Q12. The drive coils L3a and L3b are connected in series to form a W phase and are connected to the terminal 19c3. The terminal 19c3 is connected to the collector of the drive transistor Q13. The bases of the drive transistors Q11, Q12 and Q13 are connected to the control circuit 23. The other ends of the U-phase, V-phase, and W-phase drive coils are commonly connected and connected to the terminal 19c4, and are connected to the power supply together with the control circuit 23.

[0005]

However, in such a conventional brushless motor, the relationship between the rotational speed of the motor and the torque characteristic is uniquely determined as shown in (Equation 1), and the high torque characteristic and the high speed characteristic are obtained. There is a problem that it is difficult to achieve both rotation.

[0006]

[Equation 1]

The present invention has been made in view of such problems of the conventional brushless motor, and an object thereof is to provide a small-sized and high-output brushless motor capable of high-speed rotation.

[0008]

In order to achieve this object, the brushless motor of the present invention forms each energized phase.
An intermediate terminal is provided on the stator composed of n driving coils,
The drive transistor is connected to the intermediate terminal.

[0009]

With this configuration, when electric current is applied to both ends of the drive coil during normal rotation, the torque characteristic of the motor is proportional to the number of windings, and is a proportional expression of (Equation 2).

[0010]

[Equation 2]

On the other hand, when one end of the drive coil and the intermediate terminal are energized, the torque characteristic of the motor can be changed by the ratio of (Equation 3) due to the decrease in the number of windings of the drive coil. Therefore, the number of rotations can be increased.

[0012]

[Equation 3]

As a result, a brushless motor that can rotate at high speed, is small, and has a high output can be constructed.

[0014]

1 is a sectional view showing the structure of a brushless motor according to an embodiment of the present invention. Here, the same members as those in the conventional example have the same numbers. As shown in FIG. 2, the brushless motor of this embodiment is provided with a stator 9 in which a drive coil 9a is integrally formed in a disk shape. A terminal 9c is formed outside the stator 9. As shown in FIG. 2, the drive coil 9a of the stator 9 has six coils L1a, L2a, L3a, L1b and L2 each having an angular pitch of 60 °.
b and L3b are arranged adjacent to each other in a ring shape.

The coils L1a to L3b of the drive coil 9a thus constructed are connected in series with U-phase drive coil groups L1a and L1b as shown in FIG. 3 and are connected to the terminal 9c1, and the collector of the drive transistor Q1. Connected to. The middle point of connection between the drive coils L1a and L1b is the terminal 9c4.
Connected to the collector of the drive transistor Q4. Similarly, the V-phase drive coil groups L2a and L2b are connected in series and connected to the terminal 9c2 and to the collector of the drive transistor Q2. Drive coils L2a and L
The midpoint of connection of 2b is connected to the terminal 9c5, and is connected to the collector of the drive transistor Q5. The W-phase drive coil groups L3a and L3b are connected in series, connected to the terminal 9c3, and connected to the collector of the drive transistor Q3. The midpoint of the connection between the drive coils L3a and L3b is connected to the terminal 9c6 and the collector of the drive transistor Q6.
The other ends of the coils L1a, L2a, L3a are commonly connected and connected to the terminal 9c7. The bases of the drive transistors Q1 to Q6 are connected to the control circuit 13, and switching is performed so that the drive transistors Q1, Q2 and Q3 are energized during normal rotation and the drive transistors Q4, Q5 and Q6 are energized during high speed rotation.

As described above, in the brushless motor according to the present invention, in addition to the normal rotation in which both ends of the drive coil are energized, the midpoint of the drive coil is energized as shown in FIG. The number of windings in each energized phase can be reduced to one half, and since the winding diameter does not change, the DC resistance of the drive coil can be reduced to one half, so that the torque characteristics of the motor can be reduced to one half. Therefore, the number of rotations can be doubled while maintaining the same starting torque.

In the embodiment, the stator 9 is formed integrally, but if the drive coil 9a is formed by the plating method or the etching method and the sheet stator is fixed with the insulating material, it is thinner than the integrally formed stator and the number of parts is smaller. The motor can have less

Further, in the present embodiment, the terminal is provided at the midpoint of the drive coil, but by providing the terminal from an arbitrary position of the drive coil, a motor having an arbitrary torque characteristic can be realized.

[0019]

As described above, according to the present invention, the drive coil group of each energized phase is provided with the intermediate terminal and the drive transistor is connected to energize both ends of the drive coil during normal rotation. At high speed rotation, the torque characteristics of the motor can be changed by energizing one end and the intermediate terminal of the drive coil, and a brushless motor that can rotate at high speed and is compact and has high output can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a brushless motor according to an embodiment of the present invention.

FIG. 2 is a front view of a stator according to an embodiment of the present invention.

FIG. 3 is a diagram showing an electrical configuration for driving a stator coil according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram of a brushless motor according to an embodiment of the present invention.

FIG. 5 is a sectional view of a conventional brushless motor.

FIG. 6 is a front view of a conventional stator.

FIG. 7 is a diagram showing an electrical configuration for driving a conventional stator coil.

[Explanation of symbols]

 1 Shaft 2 Rotor Boss 3 Permanent Magnet 4 Rotor Frame 5 Sub-Rotor Yoke 6 Metal 7 Thrust Receiver 8 Housing 9 Stator 9a Drive Coil 9c Terminal 13 Control Circuit

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[Procedure amendment]

[Submission date] October 12, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. A rotor having a permanent magnet having 2 m poles in which N poles and S poles are alternately magnetized, a rotor frame made of a magnetic material for fixing the permanent magnets, and the rotor being rotatably held. A brushless motor comprising: a bracket; and a stator having an intermediate terminal provided in a group of 3n drive coils forming each energized phase.