JPH06133523A - Actuator - Google Patents

Abstract

PURPOSE:To provide a high output downsized voice coil type linear actuator in which the output shaft can be controlled highly accurately. CONSTITUTION:A pair of permanent ring magnets 2, 2 are incorporated, while opposing the same poles to each other, in a yoke comprising a pair of board type side yoke parts 4, 4 and a cylindrical yoke part 5 for connecting them integrally. A movable coil 6 is disposed between the cylindrical yoke part 5 and the outer peripheral end faces of pole pieces 3, 3 and fitted to the outer periphery of the pole piece thus increasing the cross-sectional area of the magnet while reducing leakage flux to the outside of the magnetic circuit and enhancing the flux density in the air gap efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil motor type linear actuator, in which a magnetic circuit unit and a coil unit are integrated, and a precision positioning device, an NC control device for hydraulic and pneumatic valves, a robot arm, and an assembling device. The present invention relates to a small high-performance actuator that can be used in various applications such as.

[0002]

2. Description of the Related Art A voice coil motor (Voice Co
il Motor) is a motor in which only the movable coil part moves in the magnetic field created by the magnet. It is also called a movable coil type, and the rotary motion required for linear motion with a general rotary motor is linear motion. It is a linear motor that does not require a mechanism to convert to.

In the voice coil motor, the movable part is composed of a coil and a bobbin supporting the coil and is lightweight, and since only the movable coil part makes a linear motion in a strong magnetic field, the shaft output speed is extremely high. Characterized by being fast,
In addition, a closed loop system is required to control the voice coil motor, and the control system is slightly more complicated than open loop systems such as stepping motors, but the output is completely proportional to the input current and precise control is possible. There are many advantages such as a small coil inductance, excellent electrical response, smooth control without cogging and torque ripple. Conventionally, such voice coil motors have been mainly used in hard disk drives (HD
D) It has been used for head positioning of devices.

[0004]

The present inventor has previously developed a voice coil type linear actuator in which the features and advantages of the voice coil motor as described above can be easily applied in various industrial fields. 3, a pair of cylindrical members 21 and 22 having different outer diameters are coaxially arranged, one end portions thereof are connected so as to be able to conduct, and arranged between a pair of end plates 20 and 20 to form an outer cylindrical member 21 of the yoke member. A magnetic circuit for generating a static magnetic field in a required space having a cylindrical permanent magnet 23 attached to the inner peripheral surface thereof, and a movable coil 25 arranged in the space.
And the end plate 20,
An output shaft 26 and a movable coil 2 which are rotatably supported by 20
An actuator having a structure in which 5 are connected and integrated by a bobbin 24 is completed. (JP-A-4-101657)

Further, in the above invention, the magnetic circuit portion and the movable coil portion are integrated into a required frame through a bearing, and the movable coil is moved to one end of the output shaft 26 integrated with the movable coil 25. A position sensor for confirming the position, for example, a differential transformer, a position sensor such as an encoder, or a speed sensor for confirming the moving speed of the moving coil is integrated with the frame, and the controlled object is provided at the other end of the output shaft, For example, it is an actuator characterized by connecting a hydraulic valve or the like.

The actuator having this structure can perform high-speed and high-precision positioning, and can be used in various applications such as a precision positioning device, a hydraulic and pneumatic valve NC control device, a robot arm, and an assembly device. However, in recent years, there has been a demand for a linear actuator that is smaller, has higher output, and can control the output shaft with higher accuracy.

It is an object of the present invention to provide a voice coil type linear actuator which is capable of controlling an output shaft with high precision and has a small size and high output.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a pair of ring-shaped permanent magnets having a predetermined air gap, the magnetic poles arranged opposite to each other, and magnetic pole pieces fixed to the air gap side end surface are provided on the other end surface of each permanent magnet. It is built in a yoke consisting of a pair of disc-shaped side yokes arranged in a pair and a cylindrical yoke that connects and integrates these side yokes, and can be moved directly through the side yokes in the axial direction of the ring-shaped permanent magnet. The output shaft is disposed in the coil, and the coil support that connects the output shaft and the movable coil disposed between the inner peripheral surface of the cylindrical yoke portion and the outer peripheral surfaces of the pair of magnetic pole pieces is disposed in the space. It is a characteristic actuator.

The present invention provides a compact and high-power voice coil type actuator applicable to various industrial equipment.
By configuring the pair of permanent magnets so that the same magnetic poles are arranged to face each other, as in the case of a so-called inner magnet type speaker,
Further, by arranging the movable coil between the cylindrical yoke portion and the outer peripheral end face of the magnetic pole piece and covering the outer periphery of the magnetic pole piece,
It is possible to increase the cross-sectional area of the magnet, reduce leakage of the magnetic flux to the outside of the magnetic circuit, and efficiently improve the magnetic flux density of the air gap.

Further, in the present invention, for example, a coil support for connecting and integrating a movable coil and an output shaft arranged so as to be linearly movable in the axial direction at the center of the yoke is fixed to the air gap facing magnetic pole faces of the pair of permanent magnets. The conventional apparatus shown in FIG. 3 has a supporting portion for passing the inner cylindrical member 22 which is a part of the yoke in the bobbin 24 and receiving the shaft 26 by adopting the structure in which the magnetic pole pieces are arranged between the pole pieces. However, in the present invention, the configurations of the coil support and the yoke are simplified, the configuration of the entire apparatus can be simplified, and the manufacturing can be facilitated.

Further, according to the structure of the present invention, the length of the yoke can be shortened as compared with the conventional device, the magnetic flux from the magnetic circuit can be efficiently utilized, and the moving range of the output shaft is formed between the pair of magnetic pole pieces. Also, because the required space was provided, the device was significantly downsized.

The actuator of the present invention is provided with a position sensor such as a differential transformer or an encoder for confirming the moving position of the movable coil at one end of the output shaft connected and integrated with the movable coil, or of the movable coil. By arranging a speed sensor to check the moving speed,
The accuracy of the device can be improved. Further, a controlled object such as a hydraulic valve may be connected to the other end of the output shaft. It is also possible to attach a sensor for confirming the operating status of the controlled object and control the output shaft based on this signal.

The objects to be controlled include HDD devices, precision positioning devices for workpieces, measured objects, NC control devices for hydraulic and pneumatic valves, assembly devices for assembly lines, robot arms, bonding devices, etc. According to various uses, various kinds of actuator masses, strokes, coils, permanent magnets and the like can be selected to be applied to any of them.

[0014]

The operation of the actuator according to the present invention will be described in detail with reference to the drawings. 1A is a partially longitudinal explanatory view showing an embodiment of an actuator according to the present invention, and FIG. 1B is an XY vertical sectional view in the same A. FIG.

A pair of ring-shaped permanent magnets 2 are arranged so as to face each other to form a predetermined gap 1, and a ring-shaped magnetic pole piece 3 is fixed to the gap-side end surface of the ring-shaped permanent magnet 2. A pair of disc-shaped side yoke portions 4, 4 are fixed to the other end surface of the ring-shaped permanent magnet 2, and the side yoke portions 4, 4 are connected and integrated by a cylindrical tubular yoke portion 5.

That is, since the ring-shaped permanent magnet 2 and the ring-shaped magnetic pole piece 3 are surrounded by the disk-shaped side yoke portions 4 and 4 and the cylindrical yoke portion 5, leakage from the ring-shaped permanent magnet 2 is caused. The magnetic flux can be reduced. The configuration of the yoke composed of the disk-shaped side yoke portions 4 and 4 and the tubular yoke portion 5 surrounds the magnetic field generation source so that a static magnetic field is generated between the outer peripheral end surface of the magnetic pole piece 3 and the inner peripheral surface of the tubular yoke portion 5. , It can be selected as appropriate in consideration of assembling workability.

The movable coil 6 is located in the static magnetic field between the cylindrical yoke portion 5 and the outer peripheral end surfaces of the magnetic pole pieces 3 and 3, and is arranged on the outer peripheral surfaces of the magnetic pole pieces 3 and 3 so as to be externally mounted. Further, the output shaft 8 is arranged so as to be linearly movable through the bearings 9 through the disc-shaped side yoke portions 4 and 4 in the central axis direction of the pair of ring-shaped permanent magnets 2 and 2, and further in the shape of a disc. The coil support 7 is disposed in the space 1 so that the output shaft 8 and the movable coil 6 are connected and integrated. Therefore, the output shaft 8 can be moved linearly within the moving range of the coil support 7 in the gap 1. The coil support 7 is made of a non-magnetic material and may have any shape as long as it can be placed in the gap 1. The output shaft 8 is also made of a non-magnetic material.
Various shapes can be adopted depending on the application of the actuator. Therefore, as described above, the output shaft 8 can also be arranged in any axial direction in addition to the side yoke portions 4 and 4 penetrating in the central axis direction of the ring-shaped permanent magnets 2 and 2. The bearing 9 arranged on the surface of the side yoke portion facing the output shaft to smoothly reciprocate the output shaft may have any structure, but various structures such as a conventional linear ball bearing and an oil-impregnated metal bearing can be selected. .

The movable coil 6 is mounted on the magnetic pole pieces 3 and 3 at a position where a static magnetic field is generated between the inner peripheral surface of the cylindrical yoke portion 5 and the outer peripheral end surface of the magnetic pole piece, and the yoke support portion 7 is provided. It is configured to be connected to the output shaft 8 via. When power is supplied to the movable coil 6 via the lead wire 10, an axial thrust is generated in the movable coil 6 and transmitted to the output shaft 8 via the coil support 7. The lead wire 10 for energizing the movable coil 6 is guided from the movable coil 6 to the center of the yoke along the coil support 7, passes through the notch of the output shaft 8 and passes through the hollow portion of the output shaft 8 at the center of the yoke, Communicating to the outside. Since the lead wire 10 feeding the movable coil 6 is guided to the coil support 7 and passed through the hollow output shaft 8 to the outside of the device, even if the movable coil and the coil support 7 rotate, the conventional lead wire 10 is not provided. Unlike the actuator of (1), the lead wire is not broken or bent, and a means for preventing it is not necessary. Therefore, the structure of the power feeding unit is simplified and the reliability of the actuator is increased.

Ferrite magnets, alnico magnets, and rare earth cobalt magnets can be used for the pair of ring-shaped permanent magnets 2 serving as the magnetic field generation source of this actuator, and especially R is a resource centered on Nd or Pr. By using abundant light rare earths and using an R-Fe-B system permanent magnet that contains B and Fe as main components and has an extremely high energy product of 30 MGOe or more, it is possible to significantly reduce the size and output. . The ring-shaped permanent magnet 2 does not necessarily have to be a unitary body, and may be appropriately selected such as one in which a plurality of permanent magnet blocks are laminated in the axial direction, one in which a plurality of bow-shaped permanent magnets are combined, and the like. By arranging the permanent magnets 2 in a configuration such as an inner magnet type speaker type, it is possible to effectively use the entire inner surface of the side yoke.

The size of the magnetic pole piece 3 fixed to the pair of ring-shaped permanent magnets 2 may be about the same as that of the ring-shaped permanent magnet 2, and is appropriately selected according to the size and material of the permanent magnet 2. As shown in FIG. 2, in consideration of the axial thickness of the moving coil 7 and the moving range of the moving coil 7, that is, the moving range of the output shaft 8, the moving coil facing surface is extended in the direction of the permanent magnet 2. You can also

The apparatus is constructed so as to be sealed by the disc-shaped side yoke portions 4 and 4 and the tubular yoke portion 5.
As shown in A of FIG. 1, by forming one or more holes 11 on the side surface of the disk-shaped coil support body 7, it is possible to avoid air resistance when the coil support body 7 reciprocates in the axial direction. Yes, you can exercise smoothly. In addition, there is an advantage that the weight of the device can be reduced by forming the hole 11.

In the actuator according to the present invention, the magnetic field source does not directly face the movable coil, but the movable coil 6 is arranged in the static magnetic field between the inner peripheral surface of the cylindrical yoke portion 5 and the outer peripheral end surface of the magnetic pole piece 3. As a result, it is possible to effectively utilize the entire inner surface of the board-shaped side yoke portions 4 and 4, and to narrow the gap between the cylindrical yoke portion 5 and the magnetic pole pieces 3 and the magnetic pole pieces 3 and 3 to leak outside the magnetic circuit. The magnetic flux can be reduced. Within the range of this condition, a pair of permanent magnets having the same magnetic poles opposed to each other and having magnetic pole pieces fixed thereto, and a side yoke fixed to the other end surface and connected and integrated at a cylindrical yoke portion, according to an object to be controlled, A movable coil arranged between the cylindrical yoke portion and the outer peripheral end surface of the magnetic pole piece and an output shaft arranged between the magnetic pole pieces and movable linearly in the axial direction are connected and integrated by a coil support. Any configuration can be adopted.

[0023]

EXAMPLE The actuator of the present invention shown in FIG. 1A was used for comparison with the conventional device shown in FIG. When the thrust per unit volume and the thrust per unit weight were compared under the same conditions, the thrust per unit volume was 3 times as good, and the thrust per unit weight was 1.8 times as good.

[0024]

According to the present invention, a ring-shaped permanent magnet is provided in a yoke composed of a pair of disc-shaped side yoke parts arranged on the other end surface of each permanent magnet and a cylindrical yoke part for connecting and integrating these side yokes. The built-in structure simplifies the structures of the coil bobbin and the yoke, and makes it possible to downsize the device and facilitate manufacturing. Further, while increasing the magnet cross-sectional area, it is possible to reduce the leakage magnetic flux to the outside of the magnetic circuit, and efficiently increase the gap magnetic flux density between the inner peripheral surface of the cylindrical yoke portion where the movable coil is arranged and the outer peripheral end surface of the pole piece. Therefore, an actuator with high output can be obtained.

[Brief description of drawings]

FIG. 1 is a partially vertical explanatory view showing an embodiment of an actuator according to the present invention, and FIG. 1B is an XY vertical sectional view in the same A;

FIG. 2 is a longitudinal sectional explanatory view of a main part showing another embodiment of the actuator according to the present invention.

FIG. 3 is a partially longitudinal explanatory view showing a configuration example of a conventional actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air gap 2 Ring-shaped permanent magnet 3 Magnetic pole piece 4 Board-shaped side yoke part 5 Cylindrical yoke part 6 Moving coil 7 Coil support 8 Output shaft 9 Bearing 10 Lead wire 11 Hole 20 End plate 21, 22 Cylindrical material 23 Permanent magnet 24 Bobbin 25 Moving coil 26 Output shaft

Claims (1)

[Claims] 1. A pair of disc-shaped sides in which a pair of ring-shaped permanent magnets are formed on a second end face of each permanent magnet, with a predetermined gap being formed so that the same magnetic poles are arranged to face each other, and pole pieces are fixed to the gap-side end faces. The output shaft is built in a yoke composed of a yoke part and a cylindrical yoke part for connecting and integrating these side yokes, and the output shaft is arranged so as to be linearly movable through the side yoke part in the axial direction of the ring-shaped permanent magnet. An actuator characterized in that a coil support that connects a movable coil arranged between the inner peripheral surface of the cylindrical yoke portion and the outer peripheral surfaces of the pair of magnetic pole pieces to the output shaft is arranged in the gap.