JPH05176514A - Brushless motor - Google Patents

Abstract

PURPOSE:To make it possible to heighten a revolving characteristic very much even in either forward or reverse case. CONSTITUTION:In a stator 1 winding a coil 3 on the peripheries of pole teeth 1b projected and formed inward from a cylindrical base 1a, a rotor having permanent magnets 7a to which heteropolars are alternately arranged, magnetic sensitive elements 8 (8a, 8a, 8a, 8b, 8b and 8b) and a brushless motor including a driving circuit controlling power to the coil by detection signals of the magnetic sensitive elements, to of the magnetic sensitive elements 8 are arranged to the circumferential center of the pole teeth 1b at around an electrical angle of + or -20 deg., so that one or other of the two positioned on the opposite side is operated in accordance with the revolving direction of the rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless electric motor which is an inner rotor type and is capable of forward and reverse rotation.

[0002]

2. Description of the Related Art A brushless electric motor of this type is shown in FIGS.
In general, the stator 1, the rotor 4, the magnetic sensitive element 8 and a drive circuit (not shown) are the main constituent members. The stator 1 has a cylindrical base body 1a and a plurality of (eg, six) projecting inwardly from the cylindrical base body 1a.
, And a coil 3 wound around the magnetic pole teeth via an insulating member 2. The rotor 4 includes a rotor shaft 5, a yoke 6 made of a magnetic material fixed to the rotor shaft 5, and fixed to the outer periphery of the yoke 6 and facing the end faces of the magnetic pole teeth, for example, four segment magnets 7a, 7a, Has a permanent magnet 7 made of. The segment magnets 7a, 7a, -are arranged so that the different poles are alternately located. The magnetically sensitive element 8 is located at 3 consecutive positions.
The magnetic pole teeth 1b are arranged to detect the position of the rotor 4.
9 is a cylindrical case for fixing the outer periphery of the stator 1 by press fitting, etc., 10 and 10 are bearing bases fixed to both ends of the case 9,
Reference numerals 11 and 11 denote bearings mounted on the bearing bases 10 and 10 to rotatably support the rotor shaft 5.

As described above, the magnetic poleless motor is magnetic by virtue of the fact that the six magnetic pole teeth 1b and the four segment magnets 7a and the three magnetic sensitive elements 8 are arranged on the three magnetic pole teeth 1b. A full-wave drive of the Y connection in which the sensitive element 8 is arranged at an electrical angle of 120 ° with respect to the rotor 4 is performed. Then, the magnetically sensitive element 8 detects the position of the rotor 4 and controls the energization of the coil 3 by the detection signal to drive the rotor 4. Also,
During forward and reverse rotation, the magnetic sensitive element 8 has the same positional relationship, and therefore the same characteristics can be obtained.

[0004]

By the way, when the rotational characteristics of such a brushless motor are measured and examined, the magnetically sensitive element 8 is located at the center of the magnetic pole teeth 1b in the rotational direction of the rotor 4. It has been found that the rotation characteristics are maximized when they are positioned on the opposite side of the rotation direction by an electrical angle of about 20 °. In other words, the rotation characteristics of the above-described brushless electric motor are not so good.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a brushless electric motor which has extremely improved rotation characteristics in both forward and reverse rotations.

[0006]

In order to solve the above problems, a brushless electric motor of the present invention has a cylindrical base body and magnetic pole teeth projecting inward from the cylindrical base body and an insulating member between the magnetic pole teeth. A coil with a coil wound around it, a rotor with permanent magnets with alternating opposite poles, a magnetically sensitive element that detects the rotor position, and a coil with a detection signal from the magnetically sensitive element. In a brushless motor including a drive circuit to be controlled, two magnetic responsive elements are arranged at an electrical angle of about ± 20 ° with respect to the circumferential center of the magnetic pole teeth, and the opposite side is provided depending on the rotational direction of the rotor. It is configured such that the one located at is activated.

[0007]

According to this structure, the magnetically sensitive element operates at the position where the characteristics are best, regardless of whether the rotor rotates in the forward or reverse direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The members having the same basic functions as those of the conventional example are designated by the same reference numerals.

Reference numeral 1 denotes a stator, which is a cylindrical base body 1a formed by punching and laminating, and a plurality of (six in this embodiment) magnetic pole teeth 1b, 1b,-which are formed to project inward from the cylindrical base body 1a. And the coils 3, 3, wound around the magnetic pole teeth 1b, 1b, ─ via the insulating member 2.
Have ─. The magnetic pole teeth 1b are located at equal intervals in the circumferential direction, their tips spread symmetrically in the circumferential direction, and the inner end surface forms a curved surface corresponding to the outer peripheral surface of the rotor described later. There is.

Reference numeral 4 denotes a rotor, which has a rotor shaft 5 and a rotor shaft 5
A permanent magnet 7 composed of a yoke 6 made of a magnetic material and fixed to the outer circumference of the yoke 6 and a plurality of (four in this embodiment) segment magnets 7a, 7a, which are fixed to the outer periphery of the yoke 6 and face the end faces of the magnetic pole teeth.
Have. The segment magnets 7a, 7a, ... Are arranged so that the different poles are alternately located. Therefore, the inner end surface of the magnetic pole tooth 1b described above faces the outer peripheral surfaces of the segment magnets 7a, 7a, with a predetermined interval.

Reference numeral 8 is a magnetic sensitive element composed of a Hall element or the like, which detects the position of the rotor 4 in the same manner as the conventional one, but in this embodiment, three magnetic pole teeth 1b, 1b,
Two are provided for each 1b. Specifically, each magnetic pole tooth 1b
The element for normal rotation 8a is disposed at an electrical angle of about ± 20 ° with respect to the center of the circumferential direction of, and is located on the opposite side to the arrow CW direction (this is the positive rotation direction). , 8a, 8a, and elements that are displaced in the arrow CW direction are elements for reverse rotation 8b, 8b, 8b
Then their adjacent electrical angles are 120 °, respectively.

Reference numeral 9 denotes a case, which has a cylindrical shape and which fixes the outer periphery of the stator 1 by press fitting or the like. Bearings 10 and 10 are fixed to both ends of the case 9. 11,11 are bearings and bearing base 1
It is attached to 0 and 10 to rotatably support the rotor shaft 5.

FIG. 3 shows a drive circuit, which is a device for each forward and reverse rotation.
8a, 8a, 8a, 8b, 8b, 8b are AND circuit AN via amplifier AMP.
It is connected to D, and forward and reverse rotation direction signals CW / CCW are also input to this AND circuit AND. This rotation direction signal CW / CCW
Is a positive / negative signal, and the positive / negative signals to the positive rotation elements 8a, 8a, 8a and the reverse rotation elements 8b, 8b, 8b are inverted by the inverter IN. The AND circuit AND connected to the corresponding forward / reverse rotation elements 8a, 8b is connected to the OR circuit OR corresponding to each phase U, V, W of the coil 3. Therefore, when the forward rotation direction signal CW is input, only the detection signals of the forward rotation elements 8a, 8a, 8a are detected, and when the reverse rotation direction signal CCW is input, only the detection signals of the reverse rotation elements 8b, 8b, 8b. Is input to the OR circuit OR, and the rotor 4 can be rotated in a desired direction. And the magnetic sensitive element 8 at that time
Is an electrical angle on the opposite side of the rotor 4 depending on the direction of rotation.
Since they are deviated by about 20 °, the current value is small, the efficiency of increasing the torque is maximized, and the rotation characteristics are greatly improved.

In the embodiment, the magnetic pole teeth are six and the segment magnets are four and the phase is three, but these may be appropriately changed. Further, the magnetic sensitive element has been described as being arranged on the end faces of the magnetic pole teeth, but the point is that the magnetic sensitive element may be appropriately arranged by another method as long as the positional relationship in the rotation direction is the same.

[0015]

According to the brushless motor of the present invention, the magnetic sensitive element operates at the position where the characteristics are the best regardless of whether the rotor rotates in the forward or reverse direction, so that the current value is small and the torque is small. The increasing efficiency is maximized and the rotation characteristics are greatly improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a main part perspective view showing a positional relationship between the rotor and the magnetically sensitive element.

FIG. 3 is a drive circuit diagram thereof.

FIG. 4 is a cross-sectional view showing a conventional example.

FIG. 5 is a vertical sectional view thereof.

FIG. 6 is a main part perspective view showing a positional relationship between the rotor and the magnetically sensitive element.

[Explanation of symbols]

 1 Stator 1a Stator's cylindrical base 1b Stator's magnetic pole teeth 2 Insulation member 3 Coil 4 Rotor 5 Rotor shaft 6 Yoke 7 Permanent magnet 8 Magneto-sensitive element 8a, 8a, 8a Forward magnetic sensing element 8b , 8b, 8b Magnetically sensitive element for reverse rotation

Claims (1)

[Claims] 1. A stator having a cylindrical base body, magnetic pole teeth protruding inward from the cylindrical base body, and a coil wound around the magnetic pole teeth via an insulating member, a rotor shaft, and a rotor shaft. A rotor having a fixed magnetic material yoke and a permanent magnet fixed to the outer circumference of the yoke and facing the end faces of the magnetic pole teeth,
In a brushless motor including a magnetic sensitive element for detecting the position of a rotor and a drive circuit for controlling energization of a coil by a detection signal of the magnetic sensitive element, the magnetic sensitive element is electrically connected to the center of the magnetic pole teeth in the circumferential direction. Two brushless electric motors are arranged at an angle of ± 20 ° so that the one located on the opposite side operates depending on the rotating direction of the rotor.