JP2012191817A - Electromagnetic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic actuator which has a member contributing to an operation for returning a needle to an initial position, can suppress deformation of the member and can be highly efficiently operated by small current by suppressing flux leakage.SOLUTION: A leaf spring is connected via a space in a needle 1 between a stator 2 and a bearing unit disposed in the space inside the needle 1. The leaf spring supports rotation of the needle 1 around the x-axis, the y-axis and their combining axis. Electromagnets 3 on an upper stage side and electromagnets 3 on a lower stage side are excited so as to have the same polarity in the same rotating angle position viewed in the z-axis direction. When all of the electromagnets 3 on the lower stage side are excited at a current value i, all of the electromagnets 3 on the upper stage side are excited at a current value i+i. Each of cores of the electromagnets 3 on the upper and lower stage sides has an inner peripheral face opposing to the outer peripheral face of the needle 1 and having a shape along the outer peripheral face.

Description

  The present invention relates to an electromagnetic actuator that can be driven with multiple degrees of freedom.

  Patent Document 1 discloses a three-degree-of-freedom spherical electromagnetic actuator that can be driven in all directions on a spherical surface and is expected to be applied to drive a shoulder joint and eyeball of a robot.

  The electromagnetic actuator includes a mover and a stator that generates rotational torque about the mover about three axes (x-axis, y-axis, and z-axis). The mover includes four magnetic bodies divided along a circumferential direction parallel to the xy plane, and four permanent magnets inserted between these magnetic bodies at 90 ° intervals. The stator is disposed on the outer peripheral side of the mover via a predetermined air gap, and is divided into upper and lower parts along the z-axis direction. Each stator is formed of a magnetic material of the same material having six magnetic poles. By controlling the polarity of each magnetic pole, the movable element is rotated 360 ° around the z axis, the x axis and the y axis. Can be rotated over a predetermined angular range (see, for example, paragraph [0017] of the specification of Patent Document 1).

JP 2009-130957 A

  However, in the electromagnetic actuator having the above configuration, there is a limit on the rotation range of the mover around the x-axis and the y-axis. Therefore, when the mover is rotated beyond this limit, the mover returns to the initial position. There is an inconvenience that it cannot be restored.

  In particular, when the electromagnetic actuator is applied to a joint part of a transport robot or the like, it receives a moment resulting from the weight of the transported body or an external force applied to the arm, so that the x-axis, the y-axis, or a combination thereof is applied to the mover. A mechanical rotational torque acts around the shaft. When the mover rotates beyond the predetermined angle range due to this rotational torque, the mover may not be able to return to the return position by the electromagnetic torque generated by the stator. In this case, the intended function of the joint by the electromagnetic actuator cannot be performed, resulting in a malfunction of the transport robot.

  Therefore, in order to allow the mover to return to the initial position, it is conceivable to connect the stator and the mover with a spring. However, when the stiffness of the spring is too low, there is a problem that the spring is bent due to the weight of the mover and the mover cannot perform a desired operation.

  Further, even an electromagnetic actuator having a mover that performs such a special movement is required to be able to operate with a small amount of current with high efficiency by suppressing leakage magnetic flux.

  In view of the circumstances as described above, an object of the present invention is to mount a member that contributes to the operation of returning the mover to the initial position, and to suppress the bending of the member and further suppress the leakage magnetic flux. It is an object of the present invention to provide an electromagnetic actuator that can operate with low current and high efficiency.

In order to achieve the above object, an electromagnetic actuator according to an aspect of the present invention includes:
The first and second movable parts, the first movable part, the second movable part, and the first movable part and the second movable part so as to form a space between the first movable part and the second movable part. A mover having an output shaft for coaxially connecting the child parts;
A first electromagnet group disposed around the mover; and a second electromagnet disposed around the mover so as to correspond to the first electromagnet group in a direction along the output shaft. Each of the first and second electromagnet groups has an inner peripheral surface along the outer peripheral surface facing the outer peripheral surface of the mover, and the first and second A first torque centered on the output shaft, a second torque centered on the axis orthogonal to the output shaft, and a translational thrust in the direction along the output shaft, A stator generated in the mover;
A bearing unit provided in the space of the mover and supporting the rotation of the mover by the first torque;
A support member that is connected between the stator and the bearing unit via the space of the mover and supports the rotation of the mover by the second torque.

  The first torque is generated by generating magnetic fluxes in different directions in at least two of the electromagnets of the first electromagnet group of the stator (and at least two of the electromagnets of the second electromagnet group), respectively. Can be generated. Thereby, the needle | mover can rotate centering | focusing on an output shaft. Also, at least one electromagnet of the first electromagnet group, and at least one electromagnet of the second electromagnet group arranged at a rotation angle position different from the rotation angle position of the electromagnet as viewed in the direction of the output shaft. In addition, the second torque can be generated by applying currents of different values for excitation. As a result, the mover can rotate (tilt or swing) around the output shaft.

  The bearing unit supports the rotation of the mover by the first torque. On the other hand, since the support member is connected between the stator and the bearing unit, the support member supports the rotation of the mover by the second torque, and can particularly contribute to the return operation of the mover to the initial position. .

  Here, if the support member is too low in rigidity, even if bending may occur due to the weight of the mover, the translational thrust in the direction along the output axis by the first and second electromagnet groups is used. By doing so, the occurrence of the bending can be suppressed. That is, when the output shaft direction is the gravitational direction, the first and second electromagnet groups are controlled so that the translational thrust is generated in the direction opposite to the gravitational direction of the mover. The child can be returned to the initial position.

  In addition, a strict design of the support member is not required, for example, the allowable range of bending of the support member is made as small as possible.

  Furthermore, when the mover is rotated by the second torque of the mover, since the bending of the support member is suppressed, the elastic force due to the bending does not become a disturbance when the movement of the mover is controlled. Thus, the mover can be rotated.

  Furthermore, since the mover can not only rotate the mover by the first and second torques but also translate the mover in the direction along the output shaft, the application range of the electromagnetic actuator can be expanded. Can do.

  Further, in the present invention, the first and second electromagnet groups each have an inner peripheral surface along the outer peripheral surface facing the outer peripheral surface of the mover, so that the mover performs a rotation operation and a translation operation. Sometimes, the outer peripheral surface of the mover and the inner peripheral surfaces of the first and second electromagnet groups can each maintain a desired gap with high accuracy, and the gap can be kept as narrow as possible. . As a result, it is possible to realize an electromagnetic actuator that can suppress the generation of leakage magnetic flux in the gap and operate with high efficiency with a small current.

  The support member may be a leaf spring disposed in a plane perpendicular to the output shaft. When the support member is a leaf spring, the thickness of the space formed between the first and second movable parts can be reduced in the output axis direction. Thereby, thickness reduction of an electromagnetic actuator is realizable.

  As described above, according to the present invention, it is possible to realize an electromagnetic actuator in which the support member that contributes to the operation of returning the mover to the initial position is mounted and the deflection of the support member can be suppressed. Further, it is possible to operate with high efficiency with a small current while suppressing the leakage magnetic flux.

FIG. 1 is a plan view showing an electromagnetic actuator according to an embodiment of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. 1 (the same applies to the BB line or the CC line). FIG. 3 is a plan view showing the electromagnetic actuator in a state in which the first and second movable parts of the movable element are omitted in order to explain the leaf spring. 4 is a cross-sectional view showing a state in which the mover has rotated (tilted) around the x-axis from the state shown in FIG. 5A to 5C are diagrams for explaining the operation principle of the electromagnetic actuator according to the present embodiment. 6A and 6B are diagrams for explaining the operation principle for suppressing the occurrence of bending of the leaf spring.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Configuration of electromagnetic actuator]
FIG. 1 is a plan view showing an electromagnetic actuator according to an embodiment of the present invention. 2 is a cross-sectional view taken along the line AA in FIG. 1 (the same applies to the BB line or the CC line). FIG. 1 illustrates the electromagnetic actuator 100 in an xyz space having an x axis, a y axis, and a z axis that are orthogonal to each other. An electromagnetic actuator 100 according to an embodiment of the present invention is configured as a kind of a spherical actuator that can rotationally drive a mover about each of an x-axis, a y-axis, and a z-axis.

  The electromagnetic actuator 100 includes a mover 1 and a stator 2. The mover 1 includes four permanent magnetic bodies 11 that are divided along the circumferential direction in the xy plane, and four permanent magnets inserted at equal pitches (90 ° intervals) between two adjacent magnetic bodies 11. And a magnet 12 (for example, Br = 1.4T). That is, the mover 1 has two magnetic pole pairs in the circumferential direction. The permanent magnet 12 is magnetized in the direction of the arrow d shown in FIG.

  The stator 2 includes a cylindrical frame 21 that forms a wall on the outer peripheral side, and a plurality of electromagnets 3 that are provided on the frame 21 and drive the mover 1. These electromagnets 3 include a core 32 and a coil 31 wound around the core 32. Six electromagnets 3 are provided in each of the upper and lower stages. The plurality of upper electromagnets 3 (first electromagnet group) and the plurality of lower electromagnets 3 (second electromagnet group) are arranged so as to be symmetrical in the z-axis direction.

  The cores 32 are attached to the inner peripheral surface side of the frame 21 at equal pitches (60 ° intervals as viewed in the z-axis direction) so as to protrude toward the mover 1. The tip surface of the magnetic pole 321 that is the end portion of the core 32 faces the outer peripheral surface of the mover 1.

  The current supplied to each coil 31 can be controlled independently, whereby the amount of excitation in each of the 12 magnetic poles 321 can also be controlled independently.

  As shown in FIG. 2, the mover 1 includes a first mover portion 13, a second mover portion 14, and the first mover portion 13 and the second mover portion 14 connected coaxially. And an output shaft 15. The output shaft 15 connects the first movable element 13 and the second movable element 14 so as to form a space D between them.

  The first movable part 13 and the second movable part 14 have the same configuration, and are provided between the four divided magnetic bodies 11 and these magnetic bodies 11 as described above. Each has four permanent magnets 12. The magnetic body 11 of the first mover portion 13 and the magnetic body 11 of the second mover portion 14 are respectively arranged at the same angular position when viewed in the z-axis direction. Further, the permanent magnet 12 of the first mover portion 13 and the permanent magnet 12 of the second mover portion 14 are respectively disposed at the same angular position when viewed in the z-axis direction.

  The thicknesses of the outer peripheral portions of the first and second mover portions 13 and 14 in the z-axis direction are formed to be thicker than the thicknesses of the inner peripheral portions in the z-axis direction, respectively. Thereby, the space D is divided into an inner peripheral space D1 having a wide width in the z-axis direction and an outer peripheral space D2 having a narrow width in the z-axis direction.

  The side surfaces of the first movable part 13 and the second movable part 14 are part of a spherical surface, and the first movable part 13 and the core 32 of the core 32 correspond to the spherical surfaces. Each of the surfaces facing the second movable part 14 is also a spherical surface.

  The bearing unit 4 of the output shaft 15 is provided in the inner circumferential space D1 that is the center of the output shaft 15 in the z-axis direction. The bearing unit 4 includes a bearing 41 that rotatably supports the output shaft 15 around the z axis, and a bearing holder 42 that holds the bearing unit 4.

  A leaf spring 5 as a support member is connected between the frame 21 of the stator 2 and the bearing unit 4 via a space D. The leaf spring 5 has a function of supporting the rotation of the mover 1 around the x axis, the y axis, or the combined axis thereof.

  FIG. 3 is a plan view showing the electromagnetic actuator 100 in a state where the first and second mover portions 13 and 14 of the mover 1 and the upper electromagnets 3 shown in FIG. 2 are omitted. The outer shape of the leaf spring 5 is circular. As described above, the outer peripheral edge 51 of the leaf spring 5 is connected and fixed to the frame 21, and the inner peripheral edge 52 is connected and fixed to the bearing unit 4.

  The leaf spring 5 is formed with two arc-shaped slits 54 and two arc-shaped slits 55 arranged on the outer peripheral side of the slits 54. The direction in which the slits 54 are arranged is, for example, a direction along the y-axis, and a connecting portion 53 x is formed between the ends of the slits 54. The direction in which the outer peripheral slits 55 are arranged is, for example, a direction along the x-axis, and a connecting portion 53 y is formed between the end portions of the slits 54. As a result, the mover 1 (see FIG. 2) can rotate around the x axis with the connecting portion 53x as the rotation center, and can rotate around the y axis with the connecting portion 53y as the rotation center.

  The material of the leaf spring 5 is a non-magnetic material such as stainless steel, aluminum, or resin, but may be a magnetic material.

  FIG. 4 is a cross-sectional view showing a state where the mover 1 is rotated (tilted) around the x-axis from the state shown in FIG. The same applies to the y axis. As shown in this figure, the mover 1 (the output shaft 15, the first mover part 13, and the second mover part 14) rotates integrally with the bearing unit 4. Further, according to the plate spring 5 having such a configuration, the mover 1 can be rotated around the combined axis of the x and y axes by appropriately adjusting the rigidity thereof.

  As shown in FIG. 2, the inner peripheral surface 35a of the upper electromagnets 3 (first electromagnet group) and the inner peripheral surface 35b of the lower electromagnets 3 (second electromagnet group) The first movable piece 13 and the second movable piece 14 of the movable piece 1 are opposed to the outer peripheral surfaces 131 and 141, respectively. The shape of the inner peripheral surface 35a corresponds to the shape of the outer peripheral surface 131, and the shape of the inner peripheral surface 35b corresponds to the shape of the outer peripheral surface 141.

  Specifically, the outer peripheral surfaces 131 and 141 and the inner peripheral surfaces 35a and 35b are partially spherical. With such a configuration, when the mover 1 performs a rotating operation or a translational operation, the outer peripheral surfaces 131 and 141 of the mover 1 and the inner peripheral surfaces 35a and 35b of the electromagnet 3 are each accurately formed with an expected gap. And the gap can be kept as narrow as possible. As a result, it is possible to realize an electromagnetic actuator that can suppress the generation of leakage magnetic flux in the gap and operate with high efficiency with a small current.

  The shape of the outer peripheral surfaces 131 and 141 and the inner peripheral surfaces 35a and 35b is not limited to a part of a spherical surface, but may be a secondary part such as a part of an elliptical surface, a part of a hyperboloid, or a part of an elliptical paraboloid. It may be a part of a curved surface.

[Operation principle of electromagnetic actuator]
Hereinafter, the operation principle of the electromagnetic actuator 100 will be described.

  First, the principle of operation for rotational movement around the x-axis will be described. FIG. 5A shows a cross section perpendicular to the x-axis shown in FIG. 1, that is, a cross section taken along line AA. Here, there are four magnetic poles 321 in the cross section along the line AA. Further, the magnetic body 11 facing these four magnetic poles 321 exhibits S-pole magnetism depending on the magnetization direction of the permanent magnet 12.

  Now, when the coil 31 is excited so that the magnetic pole shown in FIG. 5A appears, the mover 1 can obtain torque (that is, electromagnetic torque) in the direction of the arrow in the figure. When the current of the coil 31 is reversed, the mover 1 obtains torque in the direction opposite to that shown in FIG. The amount of torque in the rotation around the x axis can be controlled by adjusting the amount of current to the coil 31 wound around the core 32 existing in the cross section along the line AA.

  Next, the rotational movement around the y-axis will be described with reference to FIG. FIG. 5B shows a cross section obtained by rotating the cross section along the line AA by 60 ° around the z axis, that is, a cross section along the line BB or CC line. Here, also in the cross section taken along the line BB and the line CC, there are four magnetic poles 321 in the cross section. Further, the magnetic body 11 facing the four magnetic poles 321 exhibits N-pole magnetism depending on the magnetization direction of the permanent magnet 12.

  Note that the y-axis is a line located between the BB line and the CC line in FIG. 1, but the magnetic pole 321 in the BB line section and the magnetic pole 321 in the CC line section are Since the respective polarities are controlled so as to have the same polarity, the principle of operation can be explained with one figure shown in FIG.

  Now, when the coil 31 is excited so that the magnetic pole shown in FIG. 5B appears, the mover 1 can obtain torque in the direction of the arrow in the figure. Further, when the current of the coil 31 is reversed, the mover 1 obtains torque in the direction opposite to that in FIG. That is, if the same magnitude of torque is applied by the same action in both the BB line cross section and the CC line cross section, the resultant force acting on the mover becomes a rotational torque around the y axis. The amount of torque in the rotation around the y-axis can be controlled by adjusting the amount of current to the coil 31 wound around the core 32 existing in the cross section taken along the line BB or the line CC.

  Finally, the operation principle of rotation around the z axis will be described with reference to FIG. FIG. 5C shows a cross-sectional view perpendicular to the z-axis. Now, the coil 31 is excited so that the magnetic pole shown in FIG. 5C appears, that is, the coil 31 is excited so that the electromagnets 180 degrees apart in the direction around the z-axis are in phase, and the mover 1 Can obtain torque in the direction of the arrow in the figure. If the same magnetic pole is generated for each of the two stators arranged along the z axis, no torque is generated on the axes other than the z axis. Further, when the current of the coil 31 is reversed, the mover 1 obtains torque in the opposite direction. The amount of torque in the rotation around the z axis can be controlled by adjusting the amount of current to the coil 31 wound around the core 32.

  As described above, the mover 1 can rotate (tilt or swing) around the x-axis or the y-axis as described with reference to FIGS. 5 (A) and 5 (B). The movable element 1 can be returned to the initial position because the leaf spring 5 is attached as described above. Further, as described above, by appropriately adjusting the rigidity of the leaf spring 5, the movable element 1 can be rotated around the combined axis of the x and y axes.

  Here, even if the leaf spring 5 is bent, the occurrence of the bending can be suppressed as follows. 6A is a plan view for explaining the principle of operation, and FIG. 6B is a cross-sectional view taken along the line AA in FIG. 6A.

For example, as shown in FIG. 6A, it is assumed that each electromagnet 3 is excited so as to have a magnetic pole as illustrated. The upper electromagnet 3 and the lower electromagnet 3 are excited so as to have the same polarity at the same rotation angle position when viewed in the z-axis direction. In the present embodiment, as shown in FIG. 6B, when all the lower electromagnets 3 are excited with the current value i _0, they are excited with the current values i ₀ + i of all the upper electromagnets 3. The That is, the difference in current value for exciting the electromagnet 3 between the lower side and the upper side is i. In this manner, the bias current i is applied to the upper electromagnet 3 so to speak, so that the bending of the leaf spring 5 is cancelled (currently, the direction of gravity is the downward direction in the z-axis direction). A translational thrust can be generated in the child 1. The current value i can be set in advance according to the design of the leaf spring 5 and other members. Thereby, the position of the needle | mover 1 can be kept at an initial position.

  In addition, a strict design of the leaf spring 5 is not required, such as making the allowable range of bending of the leaf spring 5 as small as possible.

  Further, since the bending of the leaf spring 5 is suppressed when the mover 1 rotates around the xy axis, the elastic force due to the bending does not become a disturbance when the movement of the mover 1 is controlled. Can be rotated.

  Furthermore, by appropriately controlling the bias current value, the mover 1 can be translated not only in the z-axis and xy-axis but also in the direction along the z-axis. That is, the application range of the electromagnetic actuator 100 can be expanded by driving the mover 1 so that the mover 1 is intentionally separated from the initial position. For example, when the electromagnetic actuator 100 is applied to a joint device of a robot arm for transfer, the position of the transfer object in the z-axis direction can be finely adjusted.

[Other embodiments]
The embodiment according to the present invention is not limited to the embodiment described above, and other various embodiments are realized.

  The shape, size, and the like of the output shaft 15, the frame 21, the leaf spring 5, and the first and second mover portions 13 and 14 of the mover 1 can be appropriately changed. For example, the shape, arrangement, number, etc. of the slits of the leaf spring 5 can be appropriately changed. Alternatively, a plurality of rectangular leaf springs may be provided instead of the single leaf spring 5. Although the thickness of the electromagnetic actuator 100 in the output axis direction is increased, a plurality of coil springs may be provided instead of the leaf spring 5.

  For example, a configuration in which the tilt angle of the mover 1 around the xy axis and the distance of translational movement in the z-axis direction may be detected using a sensor. In this case, for example, an optical sensor provided on the output shaft 15 or the like can be used as the sensor.

  The method for generating the translational thrust in the mover 1 is not limited to the form shown in FIG. For example, the lower-stage and upper-stage electromagnets 3 at the rotation angle positions when viewed in the z-axis direction may be excited so as to have different magnetic poles. For example, when viewed along the line AA in FIG. 6B, the two electromagnets 3 on the upper stage side are excited so as to have an N pole, and the two electromagnets 3 on the lower stage side become an S pole. Also by such a method, the translation movement of the needle | mover 1 is attained. Or you may combine such a method and the method by control of the electric current value shown in FIG.6 (B).

  The number and arrangement of the electromagnets 3 are not limited to the above embodiment, and can be changed as appropriate.

The supporting member that supports the rotation of the movable element 1 around the x-axis, the y-axis, or the combined axis thereof, that is, the tilting of the movable element 1 is not limited to the leaf spring 5. For example, it may be rubber. When the support member is not a thin member such as a leaf spring but a member having a thickness in the z-axis direction, the shape and size of the outer peripheral space D2 (see FIG. 2) and the like are appropriately designed according to the thickness. It only has to be done.
Alternatively, the support member is not limited to a member that is intentionally given an elastic force by the designer at the time of design, and is a member that can support the tilting operation and deforms following the tilting (elastic deformation). Any member can be used as long as it does.

D: Space 1 ... Movable element 2 ... Stator 3 ... Electromagnet 4 ... Bearing unit 5 ... Leaf spring (corresponding to support member)
DESCRIPTION OF SYMBOLS 13 ... 1st needle | mover part 14 ... 2nd needle | mover part 15 ... Output shaft 100 ... Electromagnetic actuator

Claims (2)

The first and second movable parts, the first movable part, the second movable part, and the first movable part and the second movable part so as to form a space between the first movable part and the second movable part. A mover having an output shaft for coaxially connecting the child parts;
A first electromagnet group disposed around the mover; and a second electromagnet disposed around the mover so as to correspond to the first electromagnet group in a direction along the output shaft. Each of the first and second electromagnet groups has an inner peripheral surface along the outer peripheral surface facing the outer peripheral surface of the mover, and the first and second A first torque centered on the output shaft, a second torque centered on the axis orthogonal to the output shaft, and a translational thrust in the direction along the output shaft, A stator generated in the mover;
A bearing unit provided in the space of the mover and supporting the rotation of the mover by the first torque;
A support member connected between the stator and the bearing unit via the space of the mover, and supporting the rotation of the mover by the second torque;
An electromagnetic actuator comprising: The electromagnetic actuator according to claim 1,
The support member is an electromagnetic actuator that is a leaf spring disposed in a plane perpendicular to the output shaft.

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