JPS61185055A - Small-sized motor - Google Patents

Abstract

PURPOSE:To suppress a noise and a vibration by providing a slope on a tooth of a stator core, and eliminating an abrupt change of an air gap, thereby reducing a cogging generating point. CONSTITUTION:A stator core 7 has salient poles of teeth 8, and the salient pole has a single stator winding 12. A slope 15 for preventing the abrupt change of an air gap is formed on the tooth 8 to the rotor 1. The energization of the winding 12 is controlled on the basis of the output of a single position detector for detecting the rotating position of the rotor 1. The slope 15 continues the prescribed gradient at the difference of an air gap between a wide portion 13 and a narrow portion 15. This slope 15 may be formed to be a curved shape.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a DC brushless motor, and is particularly aimed at reducing the size and noise.

(b) Conventional technology A conventional example of such a motor is [Fractton
al and 5ubfractional H
orsepower Electric Moto
rsJ, CYRIL G.

There is something like the one described on page 281 of VEINOTT. This is a DC brushless motor equipped with a rotor having four magnetic poles and a stator having four teeth, and the air gap between the magnet and the teeth changes into two stages: wide and narrow.

(c) Problems to be Solved by the Invention In the above motor, cogging occurs at the air gap change point and the polarity change point, which causes noise and vibration when the motor is driven. Furthermore, since a mechanical contact piece is used as a position detector, there are problems such as electromagnetic noise generated from this contact point.

In view of these problems, the present invention provides a small motor that reduces cogging and suppresses noise and vibration during driving.

(b) Means for Solving the Problems The small motor of the present invention has the same number of teeth as the number of poles of the magnet on the rotor, and the magnets and teeth are arranged so that the rotor stops at a fixed position when no current is applied. In a salient pole type DC brushless motor that changes the air gap to wide and narrow multiple stages, the slope part provided on the teeth to prevent sudden changes in the air gap and the adjacent teeth have different polarities and are connected in a single phase. a stator winding, a single position detection element that detects the rotational position of the rotor, and a control unit that switches the direction of energization to the stator winding based on the output of this position detection element. It is.

(E) Effect When a small motor is constructed in this manner, the number of points where cogging occurs can be reduced, and noise and vibration can be suppressed. Further, by using the position detection element, electromagnetic noise generated in the contact piece of the position detector can also be suppressed.

Embodiments Below, embodiments of the present invention will be explained based on the drawings. First, in FIG. ), (4), (5)
, (6). (7) is the stator core, 4
Teeth (8), (9), (1 [, αυ) have salient poles.

This salient pole has a single stator winding circle with terminals (P) (Q), and this stator winding (1z) has teeth (8), (11 ) Rotor (1) side is 8
The rotor (1) side of the pole toner (l), tooth (9), and aυ is the N pole (
The state shown in FIG. 1) is reached. When a current is applied to the terminals (Q-terminal P), the polarities of the teeth (8) to αB are reversed to the state shown in FIG. Figure 2 is a partially enlarged view of the stator core (7) shown in Figure 1 (e.g. teeth (8)).
Components that are the same as those in FIG. 1 are designated by the same reference numerals. 0 in the figure is a wide part, and the air gap (1) between the rotor (1) side surface of the tooth (8) and the rotor (1) is wide. I is the narrow part, rotor (1) of teeth (8) 1i11
1 and the rotor (1) (i is narrower. (Is is the slope part, wide part αj and narrow part Q!1
9 continues with a constant slope (n)'. According to experiments, cogging can be sufficiently suppressed when this slope section is set to the following relationship, where T is the width of the slope.

n=(1-m)/T≦1/3 Note that this slope portion α9 is not limited to a straight line shape, but may be a curved shape.

αG is a position detection element, and is made up of, for example, a Hall element, a Hall IC1 magnetic diode, or the like.

In this way, the air gap between the rotor (1) side of the teeth (8) to the rotor (1) of the stator core (7) is divided into two stages, the wide part and the narrow part α. For example, it is generally known that when the stator winding α2 is no longer energized, the rotor (1) stops in the state shown in FIG. 1 or in a state rotated by 90°. This is a permanent magnet (3) attached to the rotor (1).
This is the rotational position where the suction and repulsion forces of teeth (8) to aυ of teeth (8) to (6) are balanced.

FIG. 3 is an electric circuit diagram showing a control section for switching the direction of current supply to the stator winding l, and the same components as in FIG. 1 are given the same reference numerals. In the figure, 0η is a DC power supply and a constant voltage diode.
) and Cυ are stabilized and supplied to the position detection element αe. 2 is a comparator, and the output is switched to H (the voltage of the DC power supply (17)) or L (the voltage is 0'') in response to a signal from the position detection element (1!19).

That is, when the position detection element (161) detects the S pole, it outputs an H level, and when it detects an N pole, it outputs an L level.

(C) to (A) are switching transistors constituting a single-phase inverter circuit, and are PNP type, NPN type, PNP type, and NPN type transistors, respectively. The (2-gradient pace terminal) of this switching transistor is connected to the output terminal of the comparator, and the collector terminals are connected to each other, and the terminal (Q) of the stator winding CLz is connected to this connection point. Transistor (c), (a)
The pace terminal is connected to the terminal Q of the stator winding a2, and the stator winding (13 terminals) is connected to the connection point where the collector terminals are connected.

Note that (5) to (2) are resistances for biasing the switching transistors (c) to (a).

(G) is a transistor that controls the supply of DC power to the single-phase inverter circuit, and is in a cutoff state when the output of the comparator (to) is at H level, and is in a conductive state when it is at L level. This comparator □□□ and the comparator (137) are housed in the same package. The g inverting input terminal (→ is the resistance (40, (4υ)
The timer (42) starts measuring time when an H level voltage is applied to the terminal (IN), and after about 1 to 2 seconds it is connected to the terminal (OUT) of the timer (42).
OUT) outputs an H level pulse.

Therefore, this comparator (to) outputs an H level when the voltage detected by overcurrent detection resistor C31 becomes higher than the voltage generated at the connection point of resistors (40, (41)).At the same time, the comparator (to) outputs an H level. Positive feedback is applied to the inverting input terminal (→) and the overcurrent detection resistor is 0! Even if the voltage generated by IK becomes small, the comparator
(to) maintains the H level output. In other words, the voltage applied to the non-inverting input terminal (4) by positive feedback is applied to the resistor (4G,
The feedback resistor is set to be somewhat higher than the voltage generated at the connection point (41).

Also, at the same time that the output of comparator ■ becomes H level voltage, timer (421) starts timing, and this timer (4a is about 1 to
After 2 seconds, a nearly H level pulse is output to the inverting input terminal (→) of the comparator (to), so the output of this comparator (to) is L.
Switch to level.

When driving the small motor shown in FIG. 1 using the control section configured as described above, if the rotor (1) is stopped in the state shown in FIG. When the pole is detected, the output of comparator (2) becomes H level. As a result, the switching transistors C4) and (C) are turned on, and a current flows to the terminal (Q) of the stator winding Q7J.
Since the polarity of is as shown in FIG. 1, the rotor (1) starts to rotate clockwise due to the attraction and repulsion action of the magnet. After that, when the rotor (1) rotates and the detected value of the position detection element wire switches from the S pole to the N pole, the polarity of the teeth (8) to aυ will be in a state opposite to that shown in Fig. 1. . This newly generated magnetic field and rotor (1)
Clockwise rotation is maintained with the rotational inertia of . Hereafter rotor (1)
The current direction of the stator winding Q7J is switched in accordance with the rotation of the rotor (1), thereby maintaining continuous rotation of the rotor (1).

Thereafter, when the load on the motor increases or the motor becomes locked, an overcurrent flows through the switching transistors (A) to (A). This overcurrent is detected by an overcurrent detection resistor 09, and when this value exceeds a predetermined value, the output of the comparator becomes H level, and the transistor turns off. As a result, the stator winding (121) is de-energized, so the rotor (1) stops in the state shown in Figure 1 or in the state in which it has rotated 90'.After about 1 to 2 seconds, the timer (42
1 times up and an H level output is given to the inverting input terminal of the comparator (to), the output of this comparator becomes L.
level, and the transistor (to) turns on.

That is, based on the stopped position of the rotor (1), energization of the stator winding α is restarted in the same manner as described above.

Note that this operation is similar when the rotor (11) gets caught at the start of energization of the motor and the motor does not start smoothly.

When the rotor (1) is continuously rotating like this,
The rotor (1) is connected between the teeth (8) and aυ of the stator core (7).
Cogging will occur if the magnetic poles of the teeth (8) to (1υ) wide part (13, narrow part 0) pass, but cogging will be sufficiently suppressed by the slope part a!19. It is possible.

FIG. 4 is a front view of main parts showing another embodiment of the motor according to the present invention, and the same components as in FIG. 1 are given the same reference numerals. (43 is the stator core with 4 teeth (44) to 07
) has salient poles. As shown in the partially enlarged view of FIG. 5, this salient pole, for example, the salient pole (c) has a wide part (48) where the air gap with the rotor (1) is wide, and a narrow part (41) where the air gap is narrow. A slope part ■ where the wide part and the narrow part (491) continue at a constant slope, and a narrow part (491) where the air gap is narrow.
The end portion 611 is different from the end portion 611.

Even when the shape of the teeth 0→ to 0η is as shown in FIG. 5, this motor can be driven in the same manner as above using the electric circuit shown in FIG. 3, so a description thereof will be omitted.

(G) Effects of the Invention The small-sized motor of the present invention is a salient pole type DC brushless motor that has the same number of teeth as the number of poles of the rotor magnet, and the air gap between the magnet and the teeth is varied in multiple steps, wide and narrow. In a motor, a gradient section provided on the teeth to prevent sudden changes in the air gap, a single stator winding in which adjacent teeth have different polarities and are connected in a single phase, and the rotational position of the rotor. Equipped with a single position detection element that detects the position detection element and a control unit that switches the current direction to the stator winding based on the output of this position detection element, it suppresses cogging that occurs due to the difference in the air gap between the two stages, wide and narrow. This makes it possible to provide a small motor with low vibration and noise.

[Brief explanation of drawings]

Fig. 1 is a front view of essential parts of a small motor showing an embodiment of the present invention, Fig. 2 is a partially enlarged view of Fig. 1, and Fig. 3 is an electric circuit diagram showing an embodiment of a control section used in the present invention. , FIG. 4 is a front view of essential parts of a small motor showing another embodiment of the present invention, and FIG. 5 is a partially enlarged view of FIG. 4. (1)...Rotor, (3) to (6)...Magnet,
(7)...Stator core, (8) to aυ...teeth, 0ri...stator winding, αri...wide part, α...
Narrow part, (Is...gradient part. Applicant Sanyo Electric Co., Ltd. and one other representative Patent attorney Shizuo Sano Figure 5

Claims (2)

[Claims] (1) In a salient-pole type DC brushless motor that has the same number of teeth as the number of poles of the rotor magnet, and the air gap between the magnet and the teeth is varied in multiple steps, wide and narrow, the A slope section that prevents sudden changes in the gap, a single stator winding in which adjacent teeth have different polarities and are connected in a single phase, and a single position detection element that detects the rotational position of the rotor. What is claimed is: 1. A small motor comprising: and a control unit that switches the direction of energization to the stator winding based on the output of the position detection element. (2) The small motor according to claim 1, wherein the slope of the slope portion is 1/3 or less.