JPS62225156A - Thin type brushless motor - Google Patents

Abstract

PURPOSE:To increase effective utilization of magnetic flux and to improve torque of a motor, by a method wherein a protrusive step portion having the same contour as that of each coil is provided at an upper surface of a stator yoke where the coils are held. CONSTITUTION:A stator is constituted by that a coil 3 of sector form is arranged in ring form on a print circuit board 2 whose base is a stator yoke l. A disk-shaped rotor is arranged in opposition to an upper surface of the stator through a gap. A protorusive step portion 13 having substantially the same contour as that of each coil 3 is provided on the upper surface of the stator yoke 3 where the coils are held. According to the protrusive step portion 13, flux of a permanent magnet which passes through a space outside of the coil and does not contribute to generation og torque can be interlinked with the coil 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a thin brushless motor in which a disk-shaped rotor is opposed to a flat-plate stator.

[Background Art 1 tjS2 Figure shows the structure of this type of motor made by Jumei, in which the stator A has a plurality of fan-shaped coils 3 arranged in a ring on a printed wiring board 2 whose base material is a flat stator yoke 1. On the printed wiring board 2 are printed wiring between each fill 3, a speed control coil 4, etc., and a cable 6 (not shown) is connected to a terminal 5 formed on one end edge. K
The zero rotor B, which is connected to the im switching circuit and the power source, has a disk-shaped permanent magnet 7 that is magnetized radially and alternately, and a force-shaped rotor yoke 8 that holds this permanent magnet 7. The permanent magnet 7 of the stator A faces the upper surface of the coil 3 of the rotor B with a gap therebetween. 10 is a magnetically sensitive element such as a Hall element that detects the position of rotor B; 11 is a bearing fixed to stator A; and 12 is rotor yoke 8.
This is a permanent magnet for speed control fixed to the periphery of the

FIG. 3(a) is a layout diagram of each coil 3 of the motor in FIG. 2,
(b) is a sectional view of the frequency #1 portion in (a), (c) is an explanatory diagram of the magnetized state of the permanent magnet 7, and FIG. , Lc electrical connection diagram (,
) and each coil L a eLb, L by the current switching circuit.
This figure shows a waveform diagram (IJ) of the fill excitation currents 1a, Ib, and rc supplied to the fill excitation currents 1a, 1b, and rc, and here, an example of a 3-phase 6-pole configuration is shown.

However, the above conventional structure has the following problems.

FIG. 5 shows the distribution state of the magnetic flux φ of the permanent magnet 7 during non-excitation, but since the stator yoke 1 is flat, the path of this magnetic flux φ is not related to the arrangement of the coil 3. Therefore, in FIG. 3 (α), the magnetic flux passing through the outer portion (indicated by diagonal lines) of each coil 3 does not contribute to the generation of torque. In other words, if the shape of each coil 3 is a perfect sector, the area of this shaded area can be set to zero, but in reality each coil 3 is shaped like a rice ball, so Accordingly, the effective utilization rate of the magnetic flux φ generated from the permanent magnet 7 decreases, and the output becomes low relative to the size of the motor.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned problems, and its purpose is to increase the effective utilization rate of the magnetic flux of the permanent magnets in this type of thin brushless motor. The goal is to improve data output.

[Disclosure 1 of the Invention] Therefore, the thin brushless motor according to the present invention has a stator A which is formed by disposing a plurality of substantially fan-shaped coils 3 in an annular manner on a printed wiring board 2 having a flat stator yoke 1 as a base material. ,
A disk-shaped rotor B which is magnetized radially in alternating NS directions and which is disposed opposite to the upper surface of the stator A through a gap, and a magnetic sensor which is disposed on the printed wiring board 2 and which detects the position of the rotor B. The coil 3 is activated by the output of the cord 10 and the magnetically sensitive element 10.
A thin brushless motor equipped with a current switching circuit that switches the current of the stator yoke 1, in which a convex stepped portion 13 having approximately the same outline as each coil 3 is provided on the upper surface of the stator yoke 1 at a portion where the coils 3 are placed. This convex stepped portion 13 has an r! which has the same shape as the center hole 14 of the coil 3 on the inside.
! The one-step portion 15 may or may not be provided.

With this configuration, the magnetic flux of the permanent magnet 7 that passes through the space outside the coil 3 and does not contribute to the generation of torque because the coil 3 is not completely fan-shaped can be linked to the coil 3, and the magnetic flux The effective utilization rate can be increased.

Embodiment FIG. 1 shows an embodiment of the present invention, which has the same structure as the conventional thin brushless motor shown in FIG.
A convex step ff1s13 having approximately the same outline as each coil 3 is provided on the upper surface of the stator yoke 1, which is the base material of the printed wiring board 2, at a portion where the filler 3 is placed. In this embodiment, a four-step portion 15 having the same shape as the center hole 14 of the coil 3 is provided at the center of the convex step portion 13, and this I! The magnetically sensitive element 10 is arranged in the first step part 15, and the magnetically sensitive element 1
Although the concave groove 16 through which the lead wire of 0 is passed is provided in the convex step 13, if the magnetic sensing element 10 is placed outside the coil 3,
There is no need to provide the recessed step portion 15.

shi・early＋・−11-Shimafu Iken tenri straight shu IPi/1
．． Since the magnetic flux φ caused by the permanent magnet 57 is concentrated on the convex step portion 13 with low magnetic resistance, the wasted magnetic flux φ passing through the shaded area in Fig. 3 can be eliminated. It is.

[Effects of the Invention 1] As described above, the present invention provides a stator in which "rice ball" shaped coils are arranged in a ring on a flat stator yoke;
A thin plastic smoker equipped with a permanent magnet rotor placed opposite the stator, in which a convex step with approximately the same outline as each coil is provided on the upper surface of the stator yoke where the coils are placed. Therefore, the coil is not completely fan-shaped.
Due to its "rice ball" shape, the magnetic flux of the permanent magnet that passes through the outside of the coil and does not contribute to torque generation can be concentrated in the coil, thereby increasing the effective utilization rate of magnetic flux and improving the motor torque. It has the advantage of being able to do something, α.

[Brief explanation of drawings]

FIG. 3 (a) is a top view of the main parts as above, (b) is a sectional view of main parts as above, (c) is an enlarged sectional view of main parts as above, Pt54 figure (a) is an electrical connection diagram as above, (b) ) is a current waveform diagram same as above, and FIG. 5 is a magnetic flux distribution diagram of the permanent magnet same as above. 1 is a stator yoke, 2 is a printed wiring board, 3 is a coil,
4 is a speed control coil, 5 is a terminal section, 6 is a cable, 7
8 is a permanent magnet, 8 is a rotor yoke, 9 is a rotor shaft, 10 is a magnetic sensing element, 11 is a bearing stand, 12 is a permanent magnet for speed control, 13 is a convex step, 14 is a center hole, and 15 is a concave step. Part, 16
is a concave groove. Agent Patent Attorney Ishi 1) Choshichi (b) ρ (C)

Claims (1)

[Claims] (1) A stator consisting of a plurality of substantially sector-shaped coils arranged in a ring on a printed wiring board with a flat stator yoke as a base material, and a stator with NS magnetized alternately in a radial manner and with an air gap on the top surface of the stator. A disc-shaped rotor that is arranged to face each other via a magnetically sensitive element that detects the position of the rotor that is arranged on a printed wiring board, and a current switching circuit that switches the current of the coil according to the output of the magnetically sensitive element. What is claimed is: 1. A thin brushless motor comprising: a convex stepped portion having substantially the same outline as each coil on a portion of the upper surface of the stator yoke on which the coils are mounted.