JPS6380748A - Brushless motor - Google Patents

Abstract

PURPOSE:To eliminate the laminated core of a stator thereby to reduce the size of a whole motor by forming a permanent magnet rotor in a columnar shape, and composing the stator of a winding aligned at a predetermined electric angle with a cylindrical yoke. CONSTITUTION:A permanent magnet rotor 1 is formed in a columnar shape having a rotor shaft 2 as a center and disposed at the center. A stator 4 is composed of windings 5 aligned circumferentially through a predetermined gap on the outer periphery of the rotor 1, a yoke 6 disposed on the outer periphery of the winding 5 and magnetic pieces 7. The windings 5 are so aligned that the electric center angle of one side between adjacent windings becomes approx. 140-150 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a brushless motor using a magnetically sensitive element such as a Hall element.

[Background Art] This type of brushless electric motor generally has a permanent magnet rotor A disposed on the outside as shown in FIG. A permanent magnet part C is attached to the rotor shaft at the center of the bottom. A stator G consisting of a laminated iron core E and a winding F is disposed inside the rotor A.

H is a bearing stand and J is a bearing.

The applicant of the present application, who has been researching this type of brushless electric motor, proposed a novel stator structure in the conventional type as shown in FIG. 8 in Japanese Patent Application No. 59-477016. In other words, this stator G has a laminated iron core E having a wide magnetic pole W and an intermediate magnetic pole N, with an electrical center angle of about 140° on one side between them, and a base of each magnetic pole W, N. It consists of a wound wire. L is a magnetically sensitive element consisting of a Hall element.

In such a general brushless motor or the brushless motor proposed earlier, if you secure the space for the bearing stand H and the space in ml and m2 for the magnetic path of the laminated core E, the motor It was difficult to reduce the outer diameter to 15 mm or less, and there was a limit to further miniaturization.

[Object of the Invention] The present invention has been made in view of the above reasons, and its object is to provide a brushless electric motor that can be downsized.

[Disclosure of the Invention] The brushless motor of the present invention includes a permanent magnet rotor, a stator, a magnetically sensitive element, and a drive circuit, in which a permanent magnet rotor is centrally mounted on the rotor shaft. The stator is formed into a cylindrical shape and arranged at the center, and the stator has windings arranged in parallel in the circumferential direction along the outer circumferential surface with a predetermined gap between the stator and the outer circumferential surface of the permanent magnet rotor. , consisting of a cylindrical yoke located on the outer periphery of the winding, and a magnetic piece located at the circumferential center of one of the windings and facing the permanent magnet rotor, and furthermore, It is characterized in that the matching S wires are arranged in parallel so that the electrical center angle on one side is about 140 to 150 degrees.

According to the present invention, the laminated core of the stator that conventional motors have is no longer necessary, and there is no need to secure a dedicated space in the radial direction for the bearing stand, so that the entire motor can be significantly downsized.

(Example) An example of the present invention will be described below based on FIGS. 1 to 6.

1 is a permanent magnet rotor in which different poles (N pole, S pole) are magnetized alternately and at equal intervals, and the rotor shaft 2 is formed in a cylindrical shape with the rotor shaft 2 provided at the center of the permanent magnet part 3. The number of poles of the zero rotor 1 is two in this embodiment, but it may be four.
Further, the magnetization distribution of the magnetic poles is sinusoidal in the circumferential direction.

4 is a winding 5. The stator is composed of a yoke 6, magnetic pieces 7, etc., and the rotor is rotated by passing a current in a predetermined direction through the windings 5 provided corresponding to the magnetic poles of the rotor 1 (two in this example). Apply rotational force to 1.

The winding 5 consists of a first winding 5a and a second wire 5b, and is arranged in parallel in the circumferential direction along the outer circumferential surface of the permanent magnet rotor 1 with a predetermined gap g interposed therebetween. . Note that the number of windings 5 may be four in principle. Each of the windings 5a and 5b has an axial winding weight approximately equal to the axial length of the permanent magnet rotor 1, and a winding weight in the circumferential direction of the outer peripheral surface of the permanent magnet rotor 1 of approximately 140 mm at the center angle.
It is wound along its outer circumferential surface so that the angle ranges from 150° to 150°, that is, so that its planar view is arcuate, and there is almost no space at the center of the winding. The electrical center angle on one side between the adjacent windings 5a and 5b is 140 to 15.
Each winding 5a so that the angle is 0°.

5b are arranged in parallel so that their one side end surfaces are in contact with each other. in particular,
As shown in FIG. 3, it is solidified into a cylindrical shape using a resin casting agent or the like. In other words, both windings 5a and 5b are not point symmetrical. Further, it is preferable that the winding 5 is bifilar wound for thermal relaxation.

The yoke 6 has a substantially cylindrical shape, with its inner diameter substantially equal to the outer diameter of the cylindrical solidified winding 5.

More specifically, the thickness t of the cylindrical portion is ensured to such an extent that the magnetic flux of the rotor 1 and the winding 5 is not saturated, the axial length of the cylindrical portion is longer than that of the rotor 1, and the cylindrical portion is A lid portion 6a is provided at the upper end of the shaped portion, and a bearing 6b is mounted at the center of the lid portion 6a. Then, the winding 5 is fixed to the inner circumferential surface by adhesive or the like so that the winding weight in the axial direction corresponds to the permanent magnet rotor l in the axial direction.

The magnetic piece 7 has a fan-shaped plate shape, and is located, for example, at the circumferential center of the first winding 5a, with its tip facing the end surface of the permanent magnet rotor 1, and its base end facing inside the yoke 6. Tangent to the circumference 1
It is fixed by attaching it or caulking it. Of course, the upper end surface may be fixed to the lid part 6a (FIG. 4). The magnetic piece 7 is
When no current flows through the winding 5, the center of the N pole or S pole of the rotor 1 is attracted to bring the rotor 1 to a stable stop. This determines the rotation direction of the rotor 1.

Reference numeral 8 denotes a base, which is approximately disk-shaped, with a bearing 8a in the center.
is installed, and the insertion hole 8b for the lead wire for the magnetically sensitive element, which will be described later.
has.

Reference numeral 9 denotes a magnetic sensing element for detecting the polarity of the rotor 1. For example, a Hall element is used, and the detection part is provided on the stator 4 or the base 8 so as to face the outer peripheral surface of the rotor 1. This magnetically sensitive element 9 outputs a detection signal when facing the north pole.

Reference numeral 10 denotes a drive circuit that controls the current direction of the winding 5 based on a detection signal from the magnetically sensitive element 9. The drive circuit 10 is configured as shown in FIG. 5, and includes three transistors Q1. Q2. Q3
is turned on and off to cause current to flow through either of the two parallel winding groups LL and L2.

When the winding 5 is a bifilar winding, both winding groups LL.

Both the first winding 5a and the second winding 5b are present in L2.

Thus, the stator 4 and the base 8 are joined so that the rotor shaft 2 is supported by the bearings 6b and Bb, and as a result, the rotor 1 is placed in the center and the electric motor is assembled.

(Operation) The operation will be explained based on FIG. 5 and FIGS. 6(a) to (f).

(a) shows a state in which no voltage is applied to the drive circuit 10 and therefore no current flows through the winding 5, and the N pole or S pole of the rotor 1 (
In FIG. 6, the center of the S pole is attracted to the magnetic piece 7 and is stably stopped.

When a voltage is applied to the drive circuit 10 in this state, the magnetic sensing element 9 does not output a detection signal because it faces the S pole, and therefore the current passes through the resistors R1 and R3 and the diode D to the transistor Q2. Current flows into the base, turning it on, and current flows through winding group L2. As a result, as shown in (b), the first
An S pole is generated in the winding 5a, and an N pole is generated in the second winding 5b. Therefore, the polarity of rotor 1 and winding 5 become the same, and they repel each other, causing rotor 1 to rotate counterclockwise.
As it rotates as shown in (d) and (e), the suction force is also applied, and it reaches the position shown in (f), which has been rotated 180 degrees.

In (f), since the magnetically sensitive element 9 faces the N pole, it outputs a detection signal and turns on the transistor Q3. Therefore, the current flows through the resistors R1, R3 and the transistor Q3 to the base of the transistor Q1 and turns it on. It turns on and current flows through the winding group L1. As a result, as shown in (f), the first winding 5a
An N pole is generated in the second winding 5b, and an S pole is generated in the second winding 5b, and the rotor 1 continues to rotate in the same manner.

Note that if the winding 5 is not a bifilar winding, the winding group L
1 may be used as the first winding 5a, and the winding group L2 may be used as the second winding 5b.

In such an electric motor, there is no need for the laminated core of the stator that conventional motors have, and there is no need to secure a dedicated space in the radial direction for the bearing stand, so that the entire electric motor can be significantly downsized. Further, since the winding 5 only needs to be wound instead of being wound around the laminated core as in the conventional case, the winding process is facilitated. Furthermore, by providing the magnetic piece 7, reliable one-way activation is guaranteed, and in addition, the direction of rotation can be easily changed by changing the mounting position of the magnetic piece 7.

[Effects of the Invention] In the brushless electric motor of the present invention, the permanent magnet rotor is formed into a cylindrical shape with a rotor shaft at the center and arranged at the center, and the stator is arranged on the outer peripheral surface of the permanent magnet rotor. a cylindrical yoke located on the outer periphery of the winding; and a cylindrical yoke located on the outer periphery of the winding; It is composed of a magnetic piece located at the center and facing the permanent magnet rotor, and the adjacent windings are arranged in parallel so that the electrical center angle on one side is approximately 140 to 150'. This eliminates the need for the laminated core of the stator that the conventional motor had, and also eliminates the need to secure a dedicated space in the radial direction for the bearing stand, making it possible to significantly downsize the entire electric motor.

[Brief explanation of the drawing]

FIG. 1 shows a second embodiment of the present invention, and A in FIG.
-A sectional view, Figure 2 is a longitudinal sectional view, Figure 3 is a perspective view of the winding, Figure 4 is a perspective view of the stator, and Figure 5 is a circuit diagram of the drive circuit. , FIGS. 6(a) to 6(f) are explanatory diagrams of its operation, FIG. 7 is a vertical sectional view of a general example, and FIG. 8 is a plan view of the previously proposed one. 1- Rotor, 4- Stator, 5- Winding, 6- Yoke,
7-Magnetic piece, 9-Magnetic sensing element, 10-Drive circuit 0g
- Predetermined gap.

Claims (1)

[Claims] (1) Rotation by passing current in a predetermined direction through a permanent magnet rotor in which different poles are magnetized alternately and at equal intervals, and windings provided corresponding to each pole of the permanent magnet rotor. A brushless brush comprising a stator that applies rotational force to a rotor, a magnetically sensitive element that detects the polarity of the permanent magnet rotor, and a drive circuit that controls the current direction of the winding based on a detection signal of the magnetically sensitive element. In the electric motor, the permanent magnet rotor is formed into a cylindrical shape with a rotor shaft at the center and is disposed at the center, and the stator has a predetermined gap between it and the outer peripheral surface of the permanent magnet rotor. a cylindrical yoke located on the outer periphery of the winding; a cylindrical yoke located at the circumferential center of any one of the windings; A brushless motor is composed of magnetic pieces provided to face a magnet rotor, and the adjacent windings are arranged in parallel so that the electrical center angle on one side is about 140 to 150°.