JPS6181162A - Brushless motor - Google Patents

Abstract

PURPOSE:To inexpensively obtain a brushless motor of lightweight with a simple structure by disposing salient poles of a stator at an obtuse angle, forming one pole width approx. 1/2 of the other, and converting by a current converter the magnetic flux direction of the stator. CONSTITUTION:A 2-pole salient pole stator 3 is secured to the periphery of a cylindrical support 2 fixed to a body casing 1, and armature windings 6 are formed on both poles 4, 5. A rotational shaft 8 is held through a bearing 7 inside the support 2, and a cup-shaped yoke 9 and a permanent magnet 10 are secured thereto to form a rotor. The magnet 10 is magnetized at two poles at an equal interval of N- and S-poles, a stator is composed of the wide pole 4 of a pole width D1 and the narrow pole 5 of 1/2 of width D2 of the pole 4, and the narrow width side is further displaced at 20-40 deg. in the rotating direction. A magnetic responsive element 11 for detecting the passing polarity of the rotor pole is mounted in the 90 deg. rotating direction side of the side side, a current converter is controlled by the output of the element 11 to supply alternately the current to the windings 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a two-pole brushless motor that uses a magnetically sensitive element such as a Hall element for position detection.

[Background technology] In recent years, a brushless DC motor using a magnetically sensitive element has been developed as shown in the figure, in order to eliminate the wear and tear of the brushes that tend to occur when using battery power. ing. This type of motor rotates a permanent magnet rotor on the outside or inside of a salient pole type stator with two-phase electromagnetic windings, but two-phase DC power! In order to eliminate the torque dead center peculiar to l1lfi, a cylindrical permanent magnet 12 consisting of a 4-pole part and an 8-pole part is used as the rotor, and the stator has a winding between the main poles 13. A commutative pole 14 without a winding is provided at , to generate an auxiliary torque having a period of 172 of the fundamental wave, and as shown in FIG. 2π)
By configuring the motor so that the auxiliary torque T2 takes a maximum value on the plus side (rotation direction side), a self-starting characteristic is provided. However, this method has the problem that the permanent magnet rotor has a complicated structure and is not easy to magnetize, and the strength of the magnetic poles in the flff1 portion easily deteriorates.Additionally, the stator has the same number of complementary poles as main poles. However, there is a problem in that it is difficult to make it smaller and lighter.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned problems, and its purpose is to have a self-starting function equivalent to the above-mentioned conventional example, and to have a rotary stator and a hydraulic magnet. The structure of the device is extremely simple, and the small size of the device provides a brushless electric device suitable for use as a device.

[Disclosure of the Invention 1 The brushless electric rock of the present invention has a two-pole permanent magnet rotor in which different magnetic poles are magnetized at equal intervals, and the center lines of both magnetic poles form an angle of 140 to 160 degrees. The width of the magnetic pole of the other 4
It is controlled by a two-pole convex plastic stator formed to be 0 to 60%, a magnetic sensing element attached to the stator and detecting the polarity of the rotor magnetic pole passing through, and a magnetic sensing element (2
) It consists of a current switching circuit that alternately switches the direction of the magnetic flux of the stator winding.It is a combination of one magnetic sensing element and a two-pole stator, which simplifies the mechanical structure and electric circuit. This is because the self-starting characteristic is obtained by the shape of the salient magnetic pole.

1 and 2 show one embodiment of the present invention. In FIGS. 1(a) and 1(b), a two-pole salient pole type stator 3 made of a laminated iron core is fixed around a cylindrical support 2 fixed to a main body casing 1, with both magnetic poles. 4
and 5 are connected in series with bifilar-wound two-phase armature windings 6, and currents in opposite directions are alternately supplied to both phases. The cylindrical support 21 has a rotating shaft 8 held therein through a bearing 7, and a cup-shaped yoke fixed to one end of the rotating shaft 8 and a cylindrical permanent magnet 10 fixed to the inner peripheral surface of the cup-shaped yoke. A rotor is constructed by these. As shown in figure (b), the permanent magnet 10 has a two-pole configuration and is magnetized at equal intervals NS#' on the circumferential surface (1), while the stator has wide magnetic poles 4 with a large magnetic pole width D1.
and a narrow magnetic pole S whose magnetic pole width D2 is approximately 1/2 that of the wide magnetic pole, and the narrow magnetic poles 5 are deviated from equally spaced positions by 20 degrees to 40 degrees in the direction of rotation. I'm forced to.

In addition, a magnetically sensitive element 11 for detecting the polarity of the passing rotor is installed at a location approximately 9 ( ) degrees away from the center line of the wide 6a pole 4 in the rotational direction. The power of element 11 is controlled by the current switching circuit shown in the figure (c>i), and the two windings of the stator In other words, the Hall element 11 as a magnetic sensing element outputs a signal only when one polarity (Nti in this embodiment) is detected, and the trunk current Q, By turning on, the transnostar Q is turned on, Q2 is turned off, the S pole is detected, and the trunk is turned off. The current is switched between winding, winding, and winding.

Next, the operation of the brushless electric melting according to the present invention will be explained with reference to FIG. When no current flows through L of winding &i6 and L2, the rotor is stopped in either the state shown in the figure (ai or Figure 1 (b)), and the N pole of the rotor is connected to the narrow magnetic pole 5. Yes
In this case, the almost center portions of the S poles are facing each other. In other words, the magnetic flux at this time is only that generated from the permanent magnet, and the induced magnetic charge can move freely in the wide magnetic pole 4, but there is not much freedom in the narrow magnetic pole 5. The rotor is stopped in a regulated positional relationship. Next volume! 6A6I: When an electric current is applied to both magnetic poles 4 and 5, the magnetization due to the armature current is heavier than the magnetization due to the permanent magnet, and the center of magnetization of the wide magnetic pole 4 is approximately the center of the magnetic pole. As the rotor moves to Since the S pole is detected, the transnostar Q2 is turned on, current flows through the winding, magnetic pole 4 is excited to the S pole, magnetic pole 5 is excited to Nli, and the rotor rotates forward (clockwise). It passes through the position shown in the figure (b) and is further attracted in the clockwise rotation direction until it reaches the position shown in the figure (c). At the second position, the N pole of the Hall element or the rotor is detected and the winding L2 is transferred to Ll. Since the current is switched, the rotor is repelled again as shown in Figure (d), and can continue rotating in the same manner as above.

FIG. 3 shows the operating characteristics of the brushless electric rock of the present invention. In the same figure, the torque curve T1, which is based only on the interaction between the magnetic flux caused by the armature current and the rotor, is switched to the fundamental wave every half cycle and becomes the upper half waveform.
The auxiliary torque curve T2 due to the interaction between the permanent magnet and the stator salient magnetic poles in the state of zero K preelectric rat is the fundamental wave T1
The point θ1θ that has a period twice that of , cuts the coordinate axis from positive to negative
2 is the stable stopping point. If the magnetic poles of the stator were provided at equal intervals, this stable stopping point would coincide with the zero point of the fundamental wave T1, but by deflecting the narrow magnetic pole 5, the auxiliary torque curve T2 can be rotated in the forward direction. shift in the direction,
Therefore, the stable stopping points θ, θ2 are located slightly to the right of the zero point of the fundamental wave T1, and the resultant torque curves T, +T are always positive curves with no dead center.

In this way, at startup, that is, when the armature current is zero, the rotor stops at a position slightly rotated in the forward rotation direction, as shown in Fig. 2(a), because the narrow magnetic poles 5 are equally spaced. This is an effect achieved by deviating from the spacing position and reducing the magnetic pole width.

[Effect 1 of the Invention As described above, the present invention provides a two-pole electric rock having the simplest configuration as an electric motor, in which the salient magnetic poles of the stator are arranged so as to form an obtuse angle with each other, and the magnetic pole width of J is A current switching circuit controlled by a magnetically sensitive element is formed at approximately 172 mm in length so as to switch the magnetic flux direction of the stator.
A circuit that switches two-phase electric current can be constructed extremely easily using a single magnetic sensing element, and there is no need to provide commutative poles on the stator or configure the permanent magnet with 41i 8 poles as in the past. This has the advantage that a brushless electric motor with a simple structure and light weight can be realized at low cost.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the brushless electric motor of the present invention; (a) is a longitudinal cross-sectional view, (b) is a cross-sectional view of main parts, (c) is a circuit diagram, and Figure 2 (a) ( bHc) (d) is a cross-sectional view of the main part showing the operation of the same as above, FIG. 3 is an operation characteristic diagram of the same as above, FIG.
b) is a schematic plan view of the stator. 1 is a main body casing, 2 is a cylindrical support, 3 is a salient pole type stator, 4 is a wide magnetic pole, 5 is a narrow magnetic pole, 6 is an armature winding,
7 is a bearing, 8 is a rotating shaft, 9 is a cup-shaped yoke, 1
0 is a permanent magnet, and 11 is a magnetic sensing element. Agent Patent Attorney Ishi 1) Chief 7th 21st °. )(b) 1 to 3 figures

Claims (1)

[Claims] (1) A two-pole permanent magnet rotor with different magnetic poles magnetized at equal intervals, the center lines of both magnetic poles forming an angle of 140 to 160 degrees, and the width of one magnetic pole being 40 to 60% of the other. A two-pole convex-pole stator is formed so that A brushless electric motor characterized by comprising a current switching circuit that alternately switches between.