JPS59201670A - Dc motor - Google Patents

Abstract

PURPOSE:To enable to accurately detect the rotating position of a rotor even when the rotor fluctuates radially by using a detector having a gap, through which a projection of a rotary plate can pass in noncontact manner. CONSTITUTION:A detector 4 is made of a U-shaped sectional pulse transducer, and a rotor 2 can pass a central gap without contact. When a high frequency current is flowed to the detector 4, the rotary plate 2 is rotated, and the projection passes the gap of the detector 4, an eddy current is generated by the rotor 2, thereby stopping the internal oscillation of the detector 4. When the recess of the rotary plate 4 passes the gap of the detector 4, the oscillation of the detector 4 is again started.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to commutation of DC motors, such as brushless DC motors.

A conventional device of this type is shown in FIG.

In the figure, (1) is a rotor made of magnetic material 2, for example iron, (2) is a rotary plate that rotates with the rotor (1) and has a protrusion around the rotor (1), and (3) is a stator made of magnetic material 9, for example iron. , (4a), (4b), and (4c) are fixed to the outer stator (3) and arranged at a predetermined distance from the protrusions of the two-turn plate (2). The detector (5) is radially magnetized and detects the rotor (11
Magnets 2, e.g. permanent magnets, are fixed around the circumference of the stator with alternating polarity.(6) is a cross section of the winding fixed to the inner stator (7), and current flows through this winding By the way.

Apply rotational torque to the rotor (1). Inner stake (
7) is fixed to the outer stator (3). In the figure.

The arrow indicates the direction of the magnetic field created by the permanent magnet (5).

Next, the operation will be explained. By the permanent magnet (5),
Around the windings (6) of the inner stator (7) there are magnetic fields with alternating directions, as indicated by the arrows in FIG. The direction of this magnetic field rotates as the rotor (1) rotates, so in order to accelerate the rotor (1) in a certain direction, the current flowing through the second winding (6) must be controlled according to changes in this magnetic field. There is a need. For this reason, for example, three detectors (4a), (4b), and (4c) are arranged on the outer stator (3) at intervals different from the intervals between the protrusions of the rotary plate (2). If we check the combination of detection outputs of the overflow state at each position and determine the direction of the current flowing through the inner stator (force winding) according to this output, torque will always be applied to the rotor (1) in a fixed direction. These detectors (4a) and (4b)
, (4c), when a high-frequency current is applied and a conductor such as a protrusion of the rotating plate (2) approaches as shown in FIG. 4) Oscillation stops. Also, as shown in FIG. 2(b).

When the cage of the rotating plate (2) approaches, the oscillation of the detector (4) starts again, and by detecting the voltage of the detector (4), the rotational position of the rotating plate (2) can be determined. I can do it.

Since the conventional DC motor is configured as above, 2
A detector (
4) Even if the protrusion of the two-rotation plate (2) approaches the detector (4), the oscillation of the detector (4) will not stop. Conversely, if the entire rotor (1) and rotating plate (2) come close to the detector, the cage part of the two rotating plates (2) will move closer to the detector (
4), the oscillation of the detector (4) stops.

In this way, a situation occurs in which the output of the detector (4) does not show the value that it should show. Since such a phenomenon often occurs when the rigidity of the bearing is low relative to 2 rotations, there is a drawback that the rotational position of the rotor supported by a magnetic bearing or the like having relatively low rigidity cannot be detected.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and the detector has a gap through which the protrusion of the one-rotation plate can pass through without contact, and the detector is arranged on both sides of this gap. By detecting the protrusions with a device, the rotational position of the rotor can be accurately detected even when the rotor is whirling in the radial direction.

The purpose is to provide a DC motor that can be commutated.

The invention will now be explained with reference to the drawings.

FIGS. 3(a) and 3(b) are perspective views showing the rectifying action of a DC motor according to an embodiment of the present invention.

In the figure, (4) is a detector consisting of, for example, a pulse transducer with a U-shaped cross section, through which a rotating body (2) can pass without contact.

A high-frequency current is applied to the detector (4), and the two-rotation plate (2) rotates, causing the protrusion to rotate as shown in Figure 3(a).
), an eddy current is generated by the two rotating body (2), and the internal oscillation of the detector (4) stops. Also, the third
As shown in Figure (b), when the cage part of the nine-turn plate (2) passes through the gap of the detector (4), the oscillation of the detector (4) starts again. Even if the rotor (1) and rotating plate (2) rotate and move in the radial direction in this way, the projection of the two rotating plates (2) can pass through the gap between the detector (4) without contact. Ba.

The convex shape of the rotating plate (2) can always be detected.

In the above embodiment, a case was shown in which the rotating plate (2) has a convex shape in the axial direction, but even if there is a convex shape in the radial direction as shown in FIG. 4) By configuring the gap so that the protrusion of the rotary plate (2) can pass therethrough without contact, the same effects as in the above embodiment can be obtained.

The housing detector is composed of one light-emitting element and one light-receiving element, and is arranged so as to sandwich the protrusion of a rotating plate (2) in a non-contact manner, and detects the passage of the protrusion by the interruption of light. A similar effect can be expected by using the container (4).

As described above, according to the present invention, the rotor is cylindrical and has magnets magnetized in the radial direction and having alternating polarity on the circumference, and is made of a magnetic material, and the rotor is arranged at a predetermined distance from the magnets. A stator made of a magnetic material having windings arranged in an annular shape facing each other, and a rotating plate having a convex shape around the periphery and rotating together with the rotation of the rotor.

A detector is fixed to the stator and detects the rotational position of the rotary plate, and the direction of the current in the winding is controlled according to the output of the detector to rotate the rotor and the rotary plate in a fixed direction. In the DC motor, the detector has a gap through which the protrusion of the rotary plate can pass through without contact, and the protrusion is detected by the detectors placed on both sides of this gap, so that the rotor Even when the rotor moves in the radial direction, the rotational position of the rotor can be detected, and there is an effect that a DC motor that can be commutated can be provided.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing the relationship between the detector and rotating plate of a conventional DC motor, Figures 2 (a) and (b) are explanatory diagrams showing the operation of a conventional DC motor, and Figure 3 (a). , (b) is a perspective view showing a rotary plate and a detector of a DC motor according to one embodiment of the present invention, and FIG. 4 is a perspective view showing a rotary plate and a detector according to another embodiment of the present invention. In the figure, (1) is the rotor, (2) is the rotating plate, (3
), (7) is the stator, (41, (4a), (
4b), (4c) is the detector, (5) is the magnet, (6)
indicates a winding. In addition, in FIG. 1, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 3 (a) Figure 4

Claims (1)

[Claims] (11) A cylindrical rotor having magnets magnetized in the radial direction and having alternating polarity on the circumference, and made of a magnetic material. A stator made of a magnetic material and having windings arranged in an annular manner.A rotary plate having a convex periphery and rotating with the rotation of the rotor, and a rotary plate fixed to the stator to control the rotational position of the rotary plate. A DC motor includes a detector for detecting current flow in the winding, and controls the direction of the current in the winding according to the output of the detector to rotate the rotor and the rotating plate in a fixed direction. A DC motor characterized in that the protrusion has a gap through which the protrusion can pass without contact, and the protrusion is detected by detectors placed on both sides of the gap. (2) The detector has a U-shaped cross section. (3) The DC motor according to claim 1, wherein the protrusion of the rotary plate is detected by a voltage change when the protrusion of the rotary plate passes through the gap when a high-frequency current is passed through the gap. The detector is composed of two light-emitting elements and a light-receiving element, and when the protrusion of the rotary plate passes through the gap, the protrusion is detected by blocking the light. The DC motor described in item 1.