JPH0197155A - Three-phase half-wave type one-sensor driven brushless motor - Google Patents

Abstract

PURPOSE:To make a 0-level section for magnet position detection and to obtain a stable position detection signal, by externally arranging a Hall sensor farther than the outside edge in the diametrical direction of a rotor frame in a state facing the outside circumference of a magnet. CONSTITUTION:A magnet 5 is mounted to an inside circumference 1a of a rotor frame 1. The outside circumferential surface 5a of the magnet 5 is partially projected to the outside edge in the diametrical direction of the rotor frame 1. Facing the section fronting onto outside the outside circumferential surface 5a of the magnet, a Hall sensor 2 is arranged in a predetermined position on the outside farther than the outside edge in the diametrical direction of the rotor frame 1. By the section where the magnet 5 is covered with the rotor frame 1, a 0-level section for a rotor position detection is made.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a 3-phase, 11-wave, 1-sensor driven brushless motor.

(Prior Art) Conventionally, this type of motor has a Hall sensor (12) for rotor position detection arranged inside the rotor frame (11) in the radial direction, as shown in FIG. A magnet Is) is provided on the inner surface of the peripheral wall of (II), and a celadon track for driving and a dedicated magnetized track for detecting the rotor position are formed on this magnet (15), and this magnetized track for rotor position detection is provided. The rotor position detection signal was obtained by applying complicated magnetization to the rotor using the Hall sensor (12).

More specifically, as shown in FIG. 4, the rotor position detection magnetized track (T) is partially magnetized with the opposite polarity to the drive magnetized track (1), and the drive in this celadon portion is A "0" level portion (p) is created by partially canceling the magnetization of the magnetized trunk, and this "0" level portion (p) is detected by the Hall sensor (2).

(Problems to be Solved by the Invention) Therefore, in the case of the conventional example described in (h) above, in order to obtain a stable rotor position detection signal, in addition to the magnetic properties of the magnet (15), the rotor frame (11) and the magnet ( 15
) or =J of each component such as the Hall sensor (12)
It was necessary to strictly set the legal accuracy and mounting position relationship. Another drawback of this type of motor is that its dimensions change significantly in the direction perpendicular to the motor axis, which directly affects the positional relationship between the magnet (+5) and the Hall sensor (12), resulting in significant changes in motor characteristics. had. Furthermore, since the Hall sensor (I2) is installed inside the rotor frame (11), it is necessarily located near the core (14), and therefore the magnetic feedback from the core (14) is Accordingly, the above “0” part (
There was also the problem that the level of p) fluctuated.

The present invention was made in order to solve the conventional problems mentioned above, and does not require strict component precision or assembly precision, is easy to manufacture, and can reduce costs, while providing a stable rotor. The second objective is to be able to reliably obtain a position detection signal.

(Means for Solving the Problems) The technical means of the present invention for achieving the object as described in I- is provided with a Hall sensor for rotor position detection and a rotor frame holding a magnet inside. The present invention is characterized in that the Hall sensor is disposed outside a radially outer end of the rotor frame so as to face the outer circumferential surface of the magnet.

(Function)] - According to the technical means of the Mud Water invention, since the Hall sensor is located outside the radial outer end of the rotor frame, there is no magnetic feedback from the core arranged within the rotor frame. In addition, the rotor frame is interposed between the "0" level part of the magnet for detecting the rotor position and the Hall sensor. In other words, when viewed from the Hall sensor, '
Since the 0" level part is covered by the rotor frame,
A completely stable level signal with no fluctuations can be obtained.

Furthermore, if the Hall sensor is installed vertically on the outer periphery of the rotor frame, the gap between the magnet and the Hall sensor can be maintained, so fluctuations in motor characteristics are extremely small.

(Example) Hereinafter, an example of a three-phase half-wave one-sensor drive brushless motor according to the present invention will be described in detail based on the drawings. In Fig. 1, (ri) is a rotor frame, (2) is a Hall sensor for detecting the rotor position, the rotor frame (1) is arranged at the end of the motor shaft (3), and the core ( 4
) and a magnet (5) are housed therein. The rotor frame (1) has a cylindrical shape with one end open, and has a plurality of notches (8) in its peripheral wall (la).
are formed at predetermined intervals, and the magnets (5) are attached along the inner surface of the peripheral wall (1a). In this installed state, the outer periphery (5a) of the magnet (5) partially protrudes to the radially outer end of the rotor frame through each notch (6), and the outer periphery (5a) of the magnet (
The Hall sensor (2) is disposed at a predetermined position outside the radially outer end of the rotor frame (1), facing the outside facing portion of the rotor frame (1).

As shown in FIG. 2(A), the magnet (5) is
Multi-pole magnetization for driving is applied from the inside, for example, a total of 12 poles including N and S poles, which makes the magnet (
5) The outer peripheral surface side is also magnetized to the same polarity as the inner side. The outer periphery (5a) of the magnet I-(5) magnetized in this way is the peripheral wall (5a) remaining between the notches ffl<(G) of the rotor frame (1).
The peripheral wall (Ia) is covered by the peripheral wall (Ia), and magnetism is blocked by the peripheral wall (Ia). Therefore, as shown in FIG. 2(B), when this magnetic shielding portion (p') faces the Hall sensor (2), the sensor output waveform is completely stabilized at the "0" level.

(Effects of the Invention) As explained above, according to the present invention, the Hall sensor is disposed outside the radial outer end of the rotor frame, facing the outer peripheral surface of the magnet, so that the magnet is attached to the rotor frame. By being covered, it is possible to create a "0" level part for position detection of this magnet,
Therefore, an almost completely stable position detection signal can be obtained. In addition, the man-hours required for celadon production are reduced, and magnetic feedback from the core is completely eliminated. Furthermore, since the detection direction of the Hall sensor coincides with the radial direction of the rotor frame, even if the magnet position changes due to dimensional changes in the rotor frame, etc. in the direction perpendicular to the motor axis, the magnet position remains stable regardless of this. The combination of these effects, such as the ability to perform position detection, makes it possible to easily manufacture and reduce costs, while also making it possible to reliably obtain a stable rotor position detection signal. .

[Brief explanation of the drawing]

Figure 1 and Figures 2 (A) and (B) show an embodiment of the present invention, Figure 1 is a partially cutaway sectional view, and Figure 2 (A) is a section line - H in Figure 1. End view along Figure 2 (B)
FIG. 2 is an explanatory diagram showing the Hall sensor output. 3 and 4 show a conventional example, with FIG. 3 being a partially cutaway sectional view, and FIG. 4 being an explanatory diagram showing the Hall sensor output. (+)...Rotor frame, (Ia)...Peripheral wall of rotor frame, (2)...Hall sensor, (5)...
・Magnet, (5a)...outer periphery of the magnet, (
6)...Notch. Figure 1. lli c+-17V-A Fig. 2 (A) Fig. 2 CB) Fig. 3

Claims (2)

[Claims] (1) A Hall sensor for detecting the rotor position and a rotor frame holding a magnet inside, the Hall sensor being placed outside the radial outer end of the rotor frame with the Hall sensor facing the outer peripheral surface of the magnet. A three-phase, half-wave, one-sensor drive brushless motor characterized by the following arrangement. (2) A plurality of notches are formed in the peripheral wall of the rotor frame, and the outer circumferential surface of the magnet partially protrudes to the outer end of the rotor frame in the radial direction through each of the notches. A three-phase, half-wave, one-sensor drive brushless motor according to claim 1, wherein said magnet is magnetized from inside or outside to obtain a signal.