JPH0623213U - Magnetic actuator - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to sufficiently meet the above requirement that the moving distance is several cm and the second resonance frequency obtained by the Bode diagram is 4 KHz or more, and a stable stationary position can be easily obtained when no current is applied. In the provision of actuators. [Structure] A rotor rotatably provided around a fixed shaft, at least one permanent magnet (A) provided in the vicinity of the rotation shaft and not in contact with the rotor, and in the vicinity of the tip of the rotor, At least one permanent magnet (B) or electromagnet (C) provided in non-contact with the rotor, and the permanent magnet (B)
Alternatively, a magnetic actuator composed of an electromagnet (D) sandwiching the electromagnet (C) with the rotor tip, and two magnetic poles of which are arranged so as to sandwich the rotor tip. [Effect] The second resonance frequency obtained from the Bode diagram is 4 KHz or more, and a stable stationary position can be easily obtained when there is no power supply.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic actuator used for various OA equipment.

[0002]

[Prior art]

 Rotary type, bearing-supported actuators that are capable of high-speed movement and have a simple structure are widely used for magnetic actuators used in various OA equipment and having a travel distance of several mm to several cm. A typical example is a head positioning actuator for a magnetic disk device or a small optical disk device. This magnetic actuator has a moving coil type actuator in which the permanent magnet is stationary and the coil interlocks, and a moving magnet type actuator in which the coil is stationary and the permanent magnet moves. Motion coil type actuators are mainly used because there is a sense of security due to the track record of use.

In recent years, there has been an increasing demand for improvement of micro positioning accuracy when a magnetic disk or an actuator of a robot is operated at high speed, and a second resonance frequency of 4 KHz or more obtained from a Bode diagram is required. Has been. However, the second resonance frequency of the conventional moving coil type or moving magnet type magnetic actuator having a moving distance of several mm to several cm is 1 to 3 KHz, and in order to move a large rotation angle range, It has the drawback that the stable stationary position when no power is supplied cannot be determined by the magnetic circuit alone.

[0004]

[Problems to be solved by the device]

 The purpose of the present invention is to provide a magnetic actuator that can sufficiently meet the above-mentioned requirement that the second resonance frequency is 4 KHz or more obtained by a Bode diagram with a moving distance of several cm, and that a stable stationary position can be easily obtained when no current is applied. Is provided.

[0005]

[Means for Solving the Problems] As a result of various studies, the present inventors have adopted a lighter rotor instead of the copper coil for the rotating movable part in a configuration in which there is a stable stationary position when no power is supplied. We devised a rotating magnetic actuator. That is, the magnetic actuator of the present invention which solves the above-mentioned problems includes a rotor rotatably provided around a fixed shaft, and at least one permanent magnet (provided in the vicinity of the rotary shaft and not in contact with the rotor). A), at least one permanent magnet (B) or electromagnet (C) provided in the vicinity of the tip of the rotor without contacting the rotor, and the permanent magnet (B) or electromagnet (C). A ferromagnet (E) having a coercive force of less than 10 oersted, which is composed of an electromagnet (D) sandwiched between the tip and the two magnetic poles so as to sandwich the tip of the rotor. And / or having a coercive force of less than 1/10 of the maximum value of the magnetic field applied by the permanent magnet, which is a ferromagnetic substance having a magnetic flux of 10 oersteds or more (F), or (E) and / or (F ) Part of the rotor A permanent magnet is used as a permanent magnet (A), or a permanent magnet with a shield made by using (E) and / or (F) above is used. is there.

[0006]

[Action]

 According to the study results of the present inventors, there are two causes that the second resonance frequency is not high in the rotary type. One is the moment of inertia of the moving body. The main material of the coil used in the motion coil type magnetic actuator is copper, and its density is 8.9 g / cm3, which is heavy, and the smaller the size, the smaller the positioning accuracy during high-speed operation (hereinafter simply referred to as "positioning accuracy"). Is disadvantageous in improving. The other is that the high-frequency magnetic field is not used for the rotation of the moving body, but is used for the abnormal resonance of the parts that make up the moving body, which is the root cause of the complexity of the structure of the moving body and overcurrent. It is the main cause.

Since the structure is simplified by adopting the structure of the actuator of the present invention, it is possible to prevent the occurrence of parasitic vibration due to a structural factor, and additionally, it is possible to generate the eddy current in the rotor. Since it is made as small as possible, parasitic vibration due to eddy current is unlikely to occur. As a result, the positioning accuracy can be improved.

The rotor of the present invention needs to be built in a magnetic actuator as a rotor so that a sufficient torque can be obtained when an electric current is passed through the coil. The generated lines of magnetic force must be able to flow through, the saturation magnetization must be large, and the magnetization must not change so much even when a current is applied to the coil. Therefore, the rotor of the present invention is a ferromagnetic material (E) having a coercive force of less than 10 oersteds and / or a ferromagnetic material of 10 oersteds or more, and the maximum value of the magnetic field applied by the permanent magnet is 10 times. It is necessary to manufacture with a material (F) having a coercive force of less than one-third.

As the permanent magnet (A) used in the present invention, it is desirable to use a stronger one in order to increase the rotating torque, and for example, a NdFeB sintered magnet or the like is preferable. Further, a shield made by using the above materials (E) and / or (F) may be attached to the permanent magnet. This is because the magnetic flux can be prevented from leaking outside the system.

The present invention will be further described below with reference to a device example. FIG. 1 is an example of the present invention. A rotor 3 rotatably mounted on a rotary shaft 1 by a bearing 2 and a rotor 3 in the vicinity of the rotary shaft 1 are in non-contact with the rotor 3 and the rotor 3 side is N-side. A permanent magnet (A) 4 provided so as to have a pole, a permanent magnet (B) 6 provided near the tip 5 of the rotor 3 so that the rotor 3 side has an S pole, and a permanent magnet ( B) A magnetic actuator comprising an electromagnet 8 which is provided so as to enclose 6 and both poles 7 and 7 ′ of which are arranged on both sides of the rotor 3, and the rotor 3 includes a bolt made of a non-magnetic material such as aluminum. An aluminum arm 10 is attached by a nut 9. Then, light functional components (not shown) such as an optical sensor element and a magnetic head are fixed to the tip of the arm 10 for various applications.

In this example, the permanent magnet (A) 4 is made of NdFeB sintered magnet having an energy product of about 45 MGOe, and the permanent magnet (B) 6 is made of a bonded magnet having an energy product of about 10 MGOe. Bearing The material of the bearing 2 is a low-priced commercial product that is roughly made of iron-based alloy parts, but it is also possible to use the same material as the rotor 3 by selecting the material. The main part of the rotor 3 is made of silicon steel with a maximum coercive force of 0.6 Oe in all directions. However, even if this is changed to a material with a coercive force of 10 Oe or more, including carbon steel, the characteristics are outstanding. No deterioration is seen.

In the non-energized state, the position where the magnetic fluxes generated by the permanent magnets (A) 4 and (B) 6 are connected through the rotor 3 is the energy stable position (the position shown in FIG. 1). Even if the rotor 3 is intentionally shifted, it will return to its original position as if the elastic spring returned to its original stable position. Therefore, the position of the rotor shown in FIG. 1 is the center position of rotation corresponding to the input current of this actuator = 0 (ampere). In this example, a part of the magnetic flux generated from the N pole of the permanent magnet (A) 4 penetrates the iron core 11 of the electromagnet 8 and is dispersed left and right, but since this magnetic flux is symmetrical, the rotor is not energized. There is no action to swing 3. When the coil 12 of the electromagnet 8 is energized, the magnetic flux generated from the iron core becomes asymmetric, and the rotor 3 rotates to a new stable position determined by the direction and magnitude of the current flowing through the coil 12.

FIG. 2 shows a magnetic actuator in which a fixed insert 13 made of duralumin is attached to a rotor 3 made of silicon steel, and the rest is the same as that of FIG. Although the structure of the rotor 3 has become complicated due to the mounting of the fixed insertion part 13, in this example, the fixed insertion part 13 extends in the direction toward the rotor tip end in a form almost parallel to the magnetic field lines passing from the bearing 2 through the rotor 3. Since it has a different structure, it is less susceptible to parasitic vibration during rotation like the case of the voice coil type.

FIG. 3 shows a permanent magnet (A) 4 of the magnetic actuator of the embodiment shown in FIG. 2, in which a shield 14 made of silicon steel is arranged and most of the magnetic flux is confined in the shield 14. By adopting such a structure, the entire device including the magnetic actuator can be downsized, and it can be used also in a device such as a magnetic disk device which does not like leakage magnetic flux. The embodiment of FIG. 4 is one in which the rotatable angle range of the rotor 3 is widened by using four permanent magnets, and the two permanent magnets (A) 15, (A) ′ are brought close to the bearing. 15 'is provided and two permanent magnets (B) 16, (B) '16' are arranged near the rotor tip portion, and 14 is a silicon steel plate for preventing the divergence of magnetic flux.

The embodiment of FIG. 5 uses an electromagnet (C) 17 instead of the permanent magnets (B) 16 and (B) '16' near the tip of the rotor 3 of the embodiment of FIG. By changing the magnitude of the current flowing through the coil 18 of the electromagnet 17, the stable position of the rotor 3 and the maximum rotational deflection angle are controlled.

In addition, as a result of actually measuring the vibration characteristics in the various examples of the present invention, it is found that the second resonance frequency is 4 KHz or more and 7 KHz or less, which is a magnetic actuator that achieves the object of the present invention. It was

As described above, in the magnetic actuator of the present invention, a strong permanent magnet such as NdF eB sintered magnet is used as the permanent magnet (A), and the rotor made of the above material is saturated with magnetization or close to it. It is possible to generate a large torque by magnetizing the magnet to a magnetic moment that is almost the same as that of a permanent magnet. Moreover, the rotor design is simple, and it is possible to contribute to the torque generation from the bearing of the rotor to the maximum diameter part of the rotor, except for the non-magnetic material part, and there is a stable position when no current is applied. Therefore, it is easy to control. Moreover, the smaller the overall size, the less the magnetic flux leaks out of the permanent magnet, and the entire soft magnetic material is easily magnetized to the maximum extent, making it easier to design.

[0018]

[Effect of device]

 In the magnetic actuator of the present invention, a rotor having a simple structure and a light weight is used as a rotor, and the rotor is magnetically held by a permanent magnet that sandwiches the rotor when no electricity is applied to the driving electromagnet, or a permanent magnet and an electromagnetic stone. Therefore, the second resonance frequency obtained from the Bode diagram becomes 4 KHz or more, and a stable stationary position can be easily obtained when there is no power supply.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a magnetic actuator of the present invention.

FIG. 2 is a conceptual diagram of a magnetic actuator in which a fixed insert made of duralumin is attached to the rotor of the magnetic actuator of FIG.

FIG. 3 is a conceptual diagram of a magnetic actuator in which a shield is arranged on a permanent magnet of the magnetic actuator of FIG.

FIG. 4 is a conceptual diagram of a magnetic actuator in which the rotatable angular range of a rotor is widened by using four permanent magnets.

5 is a conceptual diagram of a magnetic actuator using an electromagnet instead of a permanent magnet near a rotor tip portion of the magnetic actuator of FIG.

[Explanation of symbols]

1 --- Rotary shaft, 2 --- Bearing, 3 --- Rotor, 4-
--- Permanent magnet (A), 5 --- tip part, 6 --- Permanent magnet (B), 7,7 '--- pole, 8 ---- electromagnet, 9 ---
-Bolts and nuts, 10 --- arms, 11 --- iron cores, 12 --- coils, 13 --- fixed insert parts, 14
--- Shield, 15 --- Permanent magnet (A), 15'-
--- Permanent magnet (A), 16 --- Permanent magnet (B), 1
6 '--- permanent magnet (B)', 17 --- electromagnet (C), 18 --- coil

Claims (3)

[Scope of utility model registration request] 1. A rotor rotatably provided around a fixed shaft, at least one permanent magnet (A) provided in the vicinity of the rotary shaft and not in contact with the rotor, and near the tip of the rotor. And at least one permanent magnet (B) or electromagnet (C) provided in non-contact with the rotor, and the permanent magnet (B) or electromagnet (C) sandwiched by the rotor tip,
A magnetic actuator composed of an electromagnet (D) arranged such that the two magnetic poles sandwich the tip of the rotor. 2. The magnetic actuator according to claim 1, wherein the rotor is a ferromagnetic material (E) having a coercive force of less than 10 oersted and / or a ferromagnetic material having a coercive force of 10 oersted or more, which is applied by a permanent magnet. Use one that has a coercive force less than 1/10 of the maximum value of the magnetic field (F), or one in which a part of the rotor composed of (E) and / or (F) is replaced with a non-magnetic material. Magnetic actuator characterized by: 3. The magnetic actuator according to claim 1, wherein the permanent magnet (A) is a permanent magnet to which a shield formed by using the (E) and / or (F) is joined. is there.