JPH06165453A - Actuator - Google Patents

Abstract

PURPOSE:To obtain a stable torque at low cost by providing a winding that excites perpendicularly to the rotation center axis of a rotor and an electrode to flow current in the rotor in parallel with the rotation center axis. CONSTITUTION:An outer stator component 10a and inner stator component 10b, which are cylindrical parts coaxial with a shaft 1, are provided so that they contact respectively the outer periphery and inner periphery of the shaft 1 and hollow cylindrical frame 3. Windings 9a and 9b are wound around the inner and outer periphery of the hollow cylindrical frame 3. A ring-shaped electrode 5b coaxial with the shaft 1, a rotary component 4 held and fixed to a holding shaft 8, and ring-shaped electrodes 5a, 5a' coaxial with, but different in diameter from, the shaft 1, are inserted in this order into the hollow part of the hollow cylindrical frame 3. This eliminates the need of bonding a permanent magnet, fixing with resin, and molding, reducing the man-hour and cost for assembly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator utilizing a magnetic field, and more particularly to an actuator having a structure of a brushless type DC motor which does not utilize a permanent magnet.

[0002]

2. Description of the Related Art Generally, a DC motor is constructed as shown in FIG.
A field magnet side using electromagnets or permanent magnets 71a, 71b that generate field is used as a stator, and an armature side having a winding 73 in a slot of an iron core 72 made of a high magnetic permeability material is a rotor. It has a structure. The rotor receives a force according to Fleming's left-hand rule when a current flows through the winding 73 in the magnetic field, but the rotor does not rotate if the direction of the current remains in one direction. Therefore, the brush 75 mechanically switches the direction of the current flowing through the winding 73 to generate a rotational torque so that a force (= Lorentz force) acts on the rotor in the same direction. This DC motor is easy to control because it can obtain a large torque and a torque that is proportional to the amount of current flowing, but since it uses a brush to supply the current, it can stably supply a large current. Difficult to maintain and also requires brush maintenance. In order to eliminate this drawback, there is a DC motor called a brushless type. This brushless DC motor is the same in principle as the above DC motor, but the field magnet side that uses a permanent magnet to remove the brush is the rotor, the armature side is the stator, and the rotor position is detected. The electric current is electrically switched by the detection by means.

[0003]

In the brushless DC motor described above, since the permanent magnets that are sintered are used, the brushless DC motors are vulnerable to impact, and the permanent magnets may be damaged during assembly or transportation, resulting in defective products. . In order to prevent this, it is necessary to take measures such as protecting the surface of the permanent magnet with a resin, but there is a drawback in that costs such as molding, material cost, and man-hour are required when protecting the surface with the resin. In addition, the current supplied to generate the rotating torque is switched electrically, but at that time, the supply current waveform, the armature reaction, the change of the gap permeance of the gap between the rotor and the stator, etc. There is a problem that the output torque waveform pulsates due to the magnetic imbalance. The present invention has been made under the circumstances described above, and an object of the present invention is to provide an actuator that can obtain a stable rotational torque at low cost.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an actuator using a magnetic field, and more particularly to an actuator having a structure of a brushless type DC electric motor which does not use a permanent magnet. It is achieved by providing a rotor in the shape of a rotor, windings that are excited in a direction perpendicular to the central axis of rotation of the rotor, and electrodes that allow current to flow in the rotor in a direction parallel to the central axis of rotation.

[0005]

In the present invention, since the current is supplied in one direction so that the rotational torque is applied to the rotor in the magnetic flux in the direction perpendicular to the central axis of rotation, the current is supplied without using the brush. The rotational torque according to Fleming's left-hand rule can be obtained only by controlling.

[0006]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a partial sectional view showing an example of the actuator of the present invention, and FIG. 2 is a sectional view taken along the line AA ′. Further, FIG. 3 is a partial cross-sectional perspective view of the extracted rotor portion. This actuator has a structure in which the shaft 1, the retainer 2, the retaining shaft 8, the nut 14, the ring material 15, and the rotor structure 4 are the rotor 20, and the other parts are the stators. First, the rotor 20 will be described. A retainer 2 is fitted to the shaft body 1, and a retainer shaft 8 that retains and fixes the rotor component 4 is retained and fixed to the retainer 2. The holding shaft 8 has a shape in which a plurality of (8 in the figure) rods are inserted through a ring material 15 that is concentric with the shaft body 1. Further, one end of the rod member holds and fixes the cylindrical rotor structure 4 concentric with the shaft body 1, and the other end of the rod member is held and fixed by the cage 2.

Next, the stator will be described. The outer stator structure 10a and the inner stator structure 10b, which are concentric circular cylinders with the shaft body 1 and are made of a high magnetic permeability material, are the outer peripheral part of the hollow cylindrical casing 3 concentric with the shaft body 1. And the inner peripheral portion are respectively in contact with each other. Windings 9a and 9b are wound around the inner and outer peripheral portions of the hollow cylindrical casing 3. The outer stator structure 10a includes flanges 11b and 1
1c, and the internal stator structure 10b is fitted to the flange 11c. The flange 11b is fixed to the flange 11a with a bolt 13, and the flange 11a
And 11c are fitted to the shaft body 1 via bearings 12a and 12b. In the outer stator structure 10a and the inner stator structure 10b, the windings 9a and 9b are arranged in the hollow cylindrical casing 3
The magnetic flux excited by the windings 9a and 9b and the role of reducing the leakage of the magnetic flux to the outside. And the hollow cylindrical housing 3
In the hollow part of the electrode 5 is a ring-shaped electrode 5 which is concentric with the shaft 1.
b, a ring-shaped electrode 5a having a different diameter from the rotor component 4 and the shaft 1 which are held and fixed to the holding shaft 8 and which are concentric circular.
5a 'is inserted in this order. The electrodes 5a and 5a 'are arranged so as to sandwich the inner and outer peripheral portions of the ring material 15 with the seal member 6 interposed therebetween. The hollow portion of the hollow cylindrical casing 3 is filled with the conductive liquid 7, and is sealed by the seal member 6 so that the conductive liquid 7 does not leak to the outside from the ring member 15 that is the movable portion. .

FIG. 4 is a perspective view of the rotor structure 4 and a partially enlarged view thereof. The rotor structure 4 is provided with a plurality of minute holes 31 for penetrating the conductive liquid in parallel with the central axis of rotation and a hole 32 for allowing the rod material of the holding shaft 8 to pass therethrough. As the conductive liquid 7 permeates the permeation hole 31,
It can be considered as if a plurality of conducting wires were wired in parallel to the central axis of rotation. FIG. 5 is a partial cross-sectional perspective view of the hollow cylindrical housing 3 including the rotor structure 4. The electrodes 5a, 5a 'and 5b are fixed to the hollow cylindrical casing 3 and are electrically insulated in the absence of the conductive liquid 7, but normally the hollow portion of the hollow cylindrical casing 3 is electrically conductive. Since the liquid is filled with the ionic liquid 7, when an electric current is passed between the electrodes 5a, 5a ′ and 5b, an electric current is passed through the conductive liquid permeation hole 31 of the rotor structure 4. FIG. 6 shows a hollow cylindrical casing 3 and windings 9a, 9
It is the perspective view which showed the positional relationship of b. The windings 9a and 9b facing each other with the hollow cylindrical casing 3 in between are paired with each other to form a magnetic dipole.

FIG. 7 is a sectional perspective view for explaining the principle of rotation torque generation. The rotor operates according to Fleming's left-hand rule when a current flows in the conductive liquid permeation hole 31 of the rotor structure 4 filled with the conductive liquid 7 in the magnetic field generated by the windings 9a and 9b. Receive F. At this time, the windings 9a and 9b
The magnetic flux B is always outward or inward in the radial direction with respect to the rotation axis depending on the direction of the electric current flowing through the electric field. Further, since the direction of the electric current I flows between the electrodes 5a and 5b in one direction, the force F It always works only in the direction that rotates the rotor. Therefore, the rotational force can be obtained mechanically like a DC motor and without electrically switching the current like a brushless DC motor. Here, in order to generate a high rotational torque, the current I supplied to the rotor may be increased or the magnetic flux density B of the opposing winding of the stator may be increased. The supply current I can be increased by increasing the current capacity of the control amplifier, and the magnetic flux density B can be increased by increasing the number of windings or increasing the exciting current. Moreover, when a superconducting winding using a superconducting material is used, a large magnetic field (magnetic flux density) B is generated. If you control the critical temperature of the superconducting winding so that a permanent current flows,
Only the initial excitation current is supplied, and no current is supplied to the opposing winding.

The present invention is not limited to the embodiment shown in FIGS. 1 to 7, and for example, the rotor structure 4 in which the conductive liquid 7 is permeated is regarded as a mover, and the current Considering the flowing direction, it can be used as a linear actuator. Further, in the above-described embodiments of FIGS. 1 to 7, the windings 9a and 9b facing each other with the hollow cylindrical housing 3 interposed therebetween form a total of four pairs of magnetic dipoles. The magnetic dipole may be formed by using a plurality of pairs of dipole type windings.

[0011]

As described above, according to the actuator of the present invention, since the work of adhering the permanent magnet, fixing with resin, molding, etc. is omitted, the man-hours for assembling can be reduced and the cost can be reduced. Can be planned. Further, since the conductive liquid is used, there is no demagnetization at the time of high motor load, a large current can be stably supplied, controllability can be improved, and pulsation of the output torque waveform can be reduced. In addition, since a portion through which a large current flows is a liquid, it can be circulated and cooled, and heat generation can be suppressed. Furthermore, if a molded resin or the like is used as the yoke portion of the rotor, the rotor can have a low inertia, and the response can be improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an example of an actuator of the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is a partial cross-sectional perspective view of a rotor portion of the actuator of the present invention.

FIG. 4 is a perspective view of a rotor structure of an actuator of the present invention and a partially enlarged view thereof.

FIG. 5 is a partial cross-sectional perspective view of a hollow cylindrical casing including the rotor structure of the actuator of the present invention.

FIG. 6 is a perspective view showing the positional relationship between the hollow cylindrical housing and the winding wire of the actuator of the present invention.

FIG. 7 is a sectional perspective view illustrating the principle of rotational torque generation of the actuator of the present invention.

FIG. 8 is a cross-sectional view showing an example of a general DC motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shaft 2 Cage 3 Hollow cylindrical housing 4 Rotor constituent 5a, 5b Electrode 6 Seal member 7 Conductive liquid 8 Holding shaft 9a, 9b Winding 10a, 10b Stator constituent 11a, 11b, 11c Flange 12a , 12b Bearing 13 Screw 14 Nut 15 Ring material 20 Rotor 31 Conductive liquid permeation hole 32 Holding shaft hole

Claims (2)

[Claims] 1. A cylindrical rotor, a winding for exciting the rotor in a direction perpendicular to a rotation center axis of the rotor, and an electrode for flowing a current in the rotor in a direction parallel to the rotation center axis. An actuator characterized by the following. 2. The actuator according to claim 1, wherein the rotor has minute holes penetrating in a direction parallel to the central axis of rotation and is immersed in a conductive liquid.