JPS63287353A - Brushless motor - Google Patents

Abstract

PURPOSE:To simplify a composition and set it to be a thinner type, by forming each pair of large and small almost-ring-trapezoidal pole pieces saliently, and by setting the electrical angle of 160 deg. to arrange windings on the external side surfaces of the respective pole pieces. CONSTITUTION:A brushless motor is composed of a rotor and a stator, and the rotor is composed of a rotor yoke 2 with the closed upper surface, and of a disc-formed permanent magnet 1 fitted on the lower surface of the rotor yoke 2. So far as the stator is concerned, in the direction of the upper surface circumference of a disc-formed stator yoke 7, pole pieces 5a, 5b are integrally projected. Besides, an angle r formed with the center of the stator yoke 7 (the center of the brushless motor) and the center of both the pole pieces 5a, 5b is set to be the electrical angle of 160 deg., and is saliently formed. On the outer periphery of the respective pole pieces 5a, 5b, coil bobbins 6a, 6b are arranged, and windings 4a, 4b are arranged. Besides, a position detecting element 8 is set, and a printed board 9 is set on the bottom surface of a housing 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention: 1. Field of the Invention The present invention relates to a one-way self-starting brushless motor.

1. Background Art FIG. 7 shows a cross-sectional view of a conventional brushless motor used in a 77-inch motor or the like. FIG. 7 shows an outer rotor, in which a permanent magnet 22 is attached to the inner surface of a cylindrical rotor yoke 21, and a shaft 23 is attached to the center of the rotor yoke 21. The shaft 23 is supported by two bearings 26 via a cylindrical bearing pedestal 25 fixed to a case 24, and a stator 28 having a winding 27 wound thereon is disposed around the outer periphery of the bearing pedestal 25. It is.

In addition, the present applicant has already filed an application (vf'yA 1986-5
4859), but as shown in Figure 8,
Stators 28 with unique shapes have already been provided. Many of these conventional brushless motors take the form of an outer rotor as shown in FIG.
With such a structure, it is difficult to form a thin brushless motor.

FIG. 9 shows the stator side of a thin brushless motor that faces each other in the axial direction, and in such cases, a three-phase self-starting system is generally used. In Fig. 9, stator yaw 2
Three magnetic pole pieces 30 are formed on two upper surfaces, and these magnetic pole pieces 3
A winding 31 is provided around the outer periphery of the wire 0. Also, each volume #a31
A position detection element 32 is arranged between them. Such ninth
In the conventional example shown in the figure, three position detection elements 32 are required, and therefore, six power transistors are required in the drive circuit according to the number of position detection elements 32, which makes the circuit more complicated. There was also a problem that the cost was high.

[Object of the Invention 1] The present invention has been provided in view of the above-mentioned points, and provides a brushless motor that has a simple structure and can be made thin.

DISCLOSURE OF THE INVENTION 1 (Structure) The present invention provides a rotor having a disk-shaped permanent magnet in which different magnetic poles are magnetized alternately and at equal intervals, and a +i? a stator made of a magnetic material and having windings disposed face to face with the rotor; a position detection element for detecting the polarity of the magnetic poles of the rotor; In a brushless motor that is equipped with a drive circuit that rotationally drives the rotor by controlling the flowing current, two types of roughly circular rings, large and small, are arranged on the same circumference of the stator, one side facing the rotor side, and the other. A pair of trapezoidal magnetic poles are formed protruding from each other, and the center of the rotor and
By setting the angle between the circumferential center of the stator and the circumferential center of two types of adjacent magnetic pole pieces to be approximately 160 degrees in electrical angle, and placing the windings on the outer surface of each magnetic pole piece, the axial surfaces can be opposed. The smaller magnetic pole piece and the larger magnetic pole piece of the stator, which are stable at the center position with the magnetic pole of the permanent magnet of the rotor when not energized, are connected to the magnetic pole of the permanent a-stone using a position detection element. The polarity is detected and the magnet is excited in a direction that repels the magnetic poles of the permanent magnet. Furthermore, the polarity of the magnetic poles of the permanent magnet as the rotor rotates is detected by a position detection element, and the magnetic poles of the stator are distinguished from the magnetic poles of the permanent magnet. It is characterized by being able to self-start in one direction by excitation in the direction of repulsion.

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

The configuration of the brushless motor of this embodiment will be explained with reference to FIGS. 1 to 3. A brushless motor is composed of a rotor and a stator, and the rotor is composed of a rotor yoke 2 whose upper surface is open, and a disk-shaped permanent magnet 1 attached to the lower surface of the rotor yoke 2. There is. The permanent magnet 1 is axially magnetized in the circumferential direction with north and south poles spaced at equal intervals. A pongee 3 is provided at the center of the rotor yoke 2, and 140 two of the above-mentioned permanent magnets 1 are arranged IM in the axial direction. The stator is constructed as follows. That is, magnetic pole pieces 5a and 5b are integrally formed to protrude in the circumferential direction of the upper surface of the disc-shaped stator yoke 7. These magnetic pole pieces 5a, 51+ are tA1
As shown in FIG. 3 and FIG. 3, a pair of large magnetic pole pieces 5
a, 5 a and a small pair of magnetic pole pieces 5 b, 5 b
is formed. The magnetic pole piece 5a has a substantially annular trapezoid shape,
The angle α (#electrical angle) when viewed from the center of the stator yaw 27 on both sides of the magnetic pole piece 5a is approximately 140°, and the other magnetic pole piece 5b is formed at an angle β when viewed from the center of the stator yoke 7. (#
The electrical angle) is approximately 100°. Furthermore, the angle γ between the center of the stator yoke 7, that is, the center of the brushless motor, and the centers of both magnetic pole pieces 5a and 5b is set to approximately 160 degrees in electrical angle. These four magnetic pole pieces 5a,
51 is formed on the same circumference of the upper surface of the stator yoke 7 by drawing or the like so as to protrude to the extent of arithmetic.

An annular trapezoidal coil bobbin 6a, 61+ made of insulating resin is arranged on the outer periphery of each magnetic pole piece 5a, 5b, so as to cover the circumferential side of the magnetic pole piece 5a, 5b. . 8 wires 4a and 41+ are similarly formed in an annular trapezoid shape, and when fixing 8JQ 411.4 b,
Winding wire 411. - It is a 6q configuration so that N+ is lower than the upper end surface of the magnetic pole pieces 5a and 5b. The windings 4α and 4 are inserted and fixed onto the circumferential surfaces of the magnetic pole pieces 5a and 5h provided with the coil bobbin '3a+61+. Only one position detection element 8 made of a Hall IC for detecting the magnetic pole position of the permanent magnet 1 is disposed on the upper surface of the open solid electronic yoke 7 of both magnetic pole pieces 5a and 5b. A printed board 9 on which a drive circuit 13 is mounted is disposed on the bottom surface of the substantially disc-shaped housing 12, and a stator seek 7 is disposed on the upper surface side of this printed board 9. Large protruding parts such as transistors and capacitors of the drive circuit 13 mounted on the printed circuit board 9 are arranged at positions where they can be accommodated in the cavities 14 inside the magnetic pole pieces 5 a and 5 b, as shown in FIG. The cylindrical ring holder 10 is aligned with the center of the stator yoke 7 and fixed by press-fitting or caulking into a hole bored in the center. Bearings 11 are arranged above and below inside the bearing stand 10, and pivotally support the shaft 3 of the rotor gee 22.

As shown in Fig. 5, the windings 114m and 4b are wound with a pie 7 airer, and the windings 4m and 4b are wound on a 6m coil bobbin.
.

After inserting and fixing into the coil 6b, two sets of adjacent windings 4a and 4b are connected in series so that the current flows in opposite directions to each other (group A, group B), and then group A is connected in series. Two sets of coils in 8 groups are connected in parallel throughout the motor, and 2
Different types of coils L, , L, are formed. Furthermore, when forming the drive circuit 13 shown in FIG.
1 and L2 are connected so that the current direction is opposite.

As shown in FIG. 4, the drive circuit 13 receives the output of the position detection element 8 with a transistor Q3, and receives the output of the position detection element 8 through a transistor Q, which is connected in series to the fills L, , L2.
,.

Q2 is turned on and off alternately to excite the coils L, L2, and magnetize the magnetic pole pieces 51+, 51+ to the N pole or the S pole.

Next, the rotation operation will be explained based on FIG. 154 and FIG. FIG. 6(a) shows the stable position of the permanent magnet 1 of the rotor when no current is applied. The center of either the N or S pole of the permanent magnet 1, in this case the center of the S pole, stably stops at the center position of the small magnetic pole piece 5b. Here, when energized, the position detection element 8 detects the N pole of the permanent magnet 1,
Transistors Q and Ql are turned on, coiled, and a current flows through them. Therefore, an N pole is generated in the magnetic pole 5a and an S pole is generated in the magnetic pole 5b. It starts to start automatically. FIG. 6(b)(c)(d) and
The rotor continues to rotate in the same counterclockwise direction due to the repulsion and attraction of the magnetic fields generated by the magnetic pole pieces 5 m and 5 b and the magnetic field of the permanent magnet 1, and when it reaches the position Wl shown in FIG. 6(e), the position detection element 8
detects the S pole of permanent magnet 1, the output voltage becomes 0 state, transistors Q3jQ1 are turned off, and transistor Q
2 is turned on, and current flows through the fill L2. At this time, take the coil L2 wound on the pie 7 filler winding 1. is equivalent to a current flowing in the opposite direction, so each magnetic pole piece 5a, 5
The magnetic field generated at b is opposite, and the magnetic pole 5ml: S pole,
A north pole is generated in the magnetic pole piece 5b, and rotation in the same direction can be maintained due to the repulsive force with the magnetic field of the permanent magnet 1.

In such a brushless motor, the magnetic pole pieces 5a, 5
b can be easily formed by drawing the material of the stator yoke 7, etc., and the magnetic pole pieces 5a and 5b are provided in two sizes, large and small, and their positions are shifted from an electrical angle of 180° to approximately 160°.
Since the stator is assembled by inserting the @@4a, 4b wound around the circumferential side of the magnetic pole pieces 5a, 5b, the work is extremely simple, and the position detection element 8, one hole rC, power transistor Q1. Since only two Q2s are required, the price is also low. Furthermore, since the axial surfaces face each other, it can be made thin. In addition, although the example has been explained using a four-pole type, the same applies to a 2n-pole type.

[Effect of the Invention 1] As described above, the present invention includes a rotor having a disk-shaped permanent magnet in which different magnetic poles are magnetized alternately and at equal intervals, and a winding arranged face-to-face with the Tsubagi rotor. a stator made of a magnetic material, a position detection element that detects the polarity of the magnetic pole of the rotor, and a drive that rotationally drives the rotor by controlling the current flowing through the windings based on the output of the position detection element. In a brushless motor comprising a circuit, a pair of substantially annular trapezoid-shaped magnetic pole pieces of two sizes, large and small, are formed protrudingly formed on the same circumference on one surface of the stator facing the rotor side, and the center of the rotor is The angle formed by the center of the stator in the circumferential direction of two types of adjacent magnetic poles, large and small, is set to approximately 160 degrees in electrical angle, and the windings are arranged on the outer surface of each magnetic pole. The smaller and larger magnetic poles of the stator are axially opposed to each other, and are stable at the center position with the magnetic poles of the permanent magnets of the rotor when not energized. Detects the polarity of the magnetic pole of the permanent magnet and excite it in a direction that repels the magnetic pole of the permanent magnet.Furthermore, the polarity of the magnetic pole of the permanent magnet as the rotor rotates is detected by a 1N detection element to change the magnetic pole of the stator to the permanent magnet. By excitation in a direction that repels the magnetic poles of the stator, self-starting in one direction can be achieved. Large and small 2
A pair of MM magnetic poles each having a substantially annular trapezoid shape are formed to protrude, and the angle between the center of the rotor and the center of two adjacent large and small magnetic poles in the circumferential direction of the stator is approximately 160 degrees in electrical angle. By setting the winding to the outer surface of each magnetic pole,
This has the effect of easily providing a thin brushless motor with an extremely simple structure.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts of an embodiment of the present invention, FIG. 2 is a sectional view of the entire same as above, FIG. 3 is an exploded perspective view of the entire same as above, and FIG.
Figure 5 is an explanatory diagram of the same 8-line circuit; Figure 6 is an operational explanatory diagram showing the rotation principle of the same;
Fig. 7 is a cross-sectional view of the entire conventional example, Fig. 8 is a plan view of the main part showing the features of the conventional method as above, and Fig. 9 is a main part showing the main part of the conventional example of a three-phase axial surface facing type brushless motor. FIG. 1 is a permanent magnet, 2 is a rotor yoke, 4 a + 4 b is a winding, 5 a and '5 b are magnetic pole pieces, 7 is a stator yoke, 8 is a position detection element, and 13 is a drive circuit. Agent Patent Attorney Ishi 1) 艮 7 2 4 ton 6 (.) (b) (c) (d) (e) 7m

Claims (1)

[Claims] (1) A rotor having a disk-shaped permanent magnet in which different magnetic poles are magnetized alternately and at equal intervals, and a stator made of a magnetic material and having windings arranged face-to-face with the rotor. and,
A brushless motor comprising a position detection element that detects the polarity of the magnetic poles of the rotor, and a drive circuit that rotationally drives the rotor by controlling the current flowing through the windings based on the output of the position detection element. Pairs of substantially annular trapezoidal magnetic poles of two sizes, large and small, are formed protrudingly on the same circumference on one surface facing the rotor, and the center of the rotor and the stator of the adjacent two types of large and small magnetic poles are formed. What is claimed is: 1. A brushless motor, characterized in that the angle formed by the center in the circumferential direction of the brushless motor is approximately 160 electrical degrees, and windings are arranged on the outer surface of each magnetic pole.