JP2002064967A - Electromagnetic linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic linear actuator realizing a high propulsion and enabling the dimensional reduction. SOLUTION: A 1st inner yoke 20, a 1st coil 14, a middle yoke 12, a 2nd coil 16 and a 2nd inner yoke 22 are attached axially in this order to an inner wall of an outer yoke 10. A 1st permanent magnet 28 and a 2nd permanent magnet 30 magnetized radially are attached to a core 26 which is a magnetic unit so as to have the polarities of the 1st and 2nd permanent magnets 28 and 30 opposite to each other. A magnetic gap 32 is formed between the 1st inner yoke 20 and the core 26, a magnetic gap 44 is formed between the 2nd inner yoke 22 and the core 26 and magnetic gaps 43 and 55 are formed between the outer surfaces of the 1st and 2nd permanent magnets 28 and 30 and the middle yoke 12. Magnetic paths 62, 64, 66 and 68 formed by applying currents to the 1st and 2nd coils 14 and 16 pass through the middle yoke 12 but do not pass the coils 14 and 16, so that a high propulsion can be obtained. Further, by increasing the thickness of the middle yoke 12, a large stroke can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic linear actuator for converting electric energy into reciprocating kinetic energy by electromagnetic action.

[0002]

2. Description of the Related Art A conventional electromagnetic linear actuator has a core in which a permanent magnet is fixed at an axial center position inside a cylindrical coil, and the core is reciprocated with respect to the coil by applying a current to the coil. It was done. Conventionally known electromagnetic linear actuators are disclosed in, for example,
FIG. 5 shows a conventionally known electromagnetic linear actuator, which is provided in, for example, Japanese Patent No. 196832 and Japanese Patent No. 2582032.

In FIG. 5, a cylindrical first coil 72, a second coil 74, and a third coil 76 are arranged on an inner wall of a cylindrical outer yoke 70 as a fixing member in the axial direction from top to bottom. Fixed. A movable member 78 is provided at the axial center position of the first coil 72, the second coil 74, and the third coil 76 so as to be able to reciprocate. The movable member 78 includes a core 80 such as a plunger, and a cylindrical side yoke 82, a cylindrical first permanent magnet 84, a cylindrical side yoke provided on the outer surface of the core 80 so as to be axially adjacent to each other in the axial direction from top to bottom. A center yoke 86, a cylindrical second permanent magnet 88, and a cylindrical side yoke 90, three yokes 82, 86, 90 and two permanent magnets 84, 88 are connected to the core 80 by an E-ring 92. It is fixed to. A magnetic gap 94 is formed between the outer surfaces of the first permanent magnet 84 and the second permanent magnet 88 and the outer yoke 70.

The first coil 72, the second coil 74, and the third coil 76 are connected so that currents alternately flow in different directions. That is, the directions of the currents of the first coil 72 and the third coil 76 and the direction of the current of the second coil 74 are set in opposite directions. The first permanent magnet 84 and the second permanent magnet 88 use rare earth permanent magnets. The first permanent magnet 84 and the second permanent magnet 88 are magnetized in the axial direction, and a position close to each other is arranged on an N pole, and a position away from each other is arranged on an S pole.

Here, a current is passed from the front side to the back side of the drawing in the first coil 72 and the third coil 76,
In the second coil 74, current flows from the back side of the drawing to the front side. As a result, two magnetic paths are formed. The first magnetic path 96 is formed by the outer yoke 70 → the first coil 72.
→ A side yoke 82 → a first permanent magnet 84 → a center yoke 86 → a second coil 74 → a loop of the outer yoke 70 is formed. The second magnetic path 98 is connected to the outer yoke 70 →
Third coil 76 → side yoke 90 → second permanent magnet 88
→ A center yoke 86 → a second coil 74 → a loop of the outer yoke 70 is formed.

When the current flows through the first coil 72, the second coil 74, and the third coil 76, a thrust (upward force in FIG. 5) based on Fleming's left hand rule is applied to the coil 7.
2, 74, 76, but the coils 72, 74, 76
Is fixed to the outer yoke 70, which is a fixing member, so that the reaction force is generated by the first permanent magnet 84 and the second permanent magnet 88.
5, a thrust for moving the core 80 (movable member 78) downward in FIG. Conversely, when a current flowing from the back side of the drawing to the front side flows through the first coil 72 and the third coil 76 and a current flowing from the front side to the back side of the drawing flows through the second coil 74, the core 80 (movable member 78) flows through the core 80 (movable member 78). In FIG. 5, a thrust for moving upward works in FIG.

[0007]

In the conventional electromagnetic linear actuator, the magnetic paths 96, 98 are formed by the coils 72, 74,
76, the magnetic resistance is increased, the magnetic flux is reduced, and a sufficient thrust cannot be obtained despite the use of rare earth permanent magnets.
In the conventional electromagnetic linear actuator, when the stroke is further increased, the axial length of the first permanent magnet 84 and the second permanent magnet 88 that are magnetized in the axial direction must be increased. The length in the axial direction was long.

The present invention has been made in view of the above points, and has as its object to provide an electromagnetic linear actuator which can obtain high thrust and can be downsized.

[0009]

In order to achieve the above object, an electromagnetic linear actuator according to the present invention comprises a coil inside a cylindrical outer yoke, and has a core in the axial direction at the axial center of the coil. In the electromagnetic linear actuator which is provided so as to be movable, a permanent magnet is fixed outside the core, and the core is reciprocated by energizing the coil, the coil is disposed at an interval in the axial direction of the outer yoke. Composed of a coil and a second coil,
A mid yoke as a magnetic body is provided at an intermediate position between the first coil and the second coil, and a first yoke as a magnetic body fixed to the outer yoke at a position opposite to the mid yoke about the first coil. An inner yoke, a second inner yoke as a magnetic material fixed to the outer yoke at a position opposite to the mid yoke about the second coil, wherein the core is made of a magnetic material, The inner yoke forms a magnetic air gap with the core, the second inner yoke forms a magnetic air gap with the core, and the first permanent magnet and the second permanent magnet, which contact or approach the permanent magnet with each other. The first permanent magnet and the second permanent magnet are magnetized in the radial direction and the magnetic poles are arranged at different positions from each other,
A magnetic gap is formed between the outer surface of the first permanent magnet and the outer surface of the second permanent magnet and the mid yoke.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the electromagnetic linear actuator according to the present invention, and shows a state in which a coil is not energized. A first coil 14 and a second coil 16 are axially fixed to an inner wall of a cylindrical outer yoke 10 as a fixing member with a mid yoke 12 interposed therebetween. The first coil 14 and the second coil 16 are
The wires are connected so that currents flow in different directions. A first inner yoke 20 is provided on the opposite side of the mid yoke 12 about the first coil 14, and the first inner yoke 20 is fixed to an inner wall of the cylindrical outer yoke 10. A second inner yoke 22 is provided on the opposite side of the mid yoke 12 about the second coil 16, and the second inner yoke 22 is fixed to the inner wall of the cylindrical outer yoke 10.

Two coils 14 and 16 and three yokes 1
At the axial center position of the cylindrical outer yoke 10 having the inner members 2, 20, 22 fixed to the inner wall, the movable member 24 is moved in the axial direction.
Are reciprocally movable. The movable member 24 has a core 26 made of a magnetic material, and a cylindrical first permanent magnet 28 and a cylindrical second permanent magnet 30 fixedly joined to each other on the outer surface of the core 26. These first permanent magnets 2
8 and the cylindrical second permanent magnet 30 are made of rare earth permanent magnets. The first permanent magnet 28 and the second permanent magnet 30 are each magnetized in the axial direction in the radial direction, and the first permanent magnet 28 has an S pole on the inner wall side and an N pole on the outer wall side, and a second permanent magnet. Reference numeral 30 denotes an N pole on the inner wall side and an S pole on the outer wall side. That is, the outer and inner magnetic poles of the adjacent first permanent magnet 28 and second permanent magnet 30 in the radial direction are set to be different.

The first inner yoke 20 has a magnetic air gap 32.
A first protruding portion 34 that is close to the core 26 through the mid yoke 1
A first step portion 36 extending in the axial direction toward the two sides.
The first protrusion 34 has a first facing surface 38 facing the first permanent magnet 28 on a side surface. The first step portion 36 has a first step portion facing surface 40 that faces the outer surface of the first permanent magnet 28 via the magnetic gap 39. A first space 42 is formed by the first facing surface 38, the first step facing surface 40, the outer surface of the core 26, and the first permanent magnet 28. The first permanent magnet 28 can enter and exit the first space 42. Also,
The outer surface of the first permanent magnet 28 and the free tip of the mid yoke 12 face each other via the magnetic gap 43.

The second inner yoke 22 has a magnetic air gap 44.
A second protruding portion 46 that is close to the core 26 through the mid yoke 1
And a second step portion 48 extending in the axial direction toward the two sides.
The side surface of the second protrusion 46 has a second facing surface 50 facing the second permanent magnet 30. The second step portion 48 has a second step portion facing surface 52 that faces the outer surface of the second permanent magnet 30 via the magnetic gap 51. The second space 54 is formed by the second facing surface 50, the second step facing surface 54, the outer surface of the core 26, and the second permanent magnet 30. The second permanent magnet 30 can enter and exit the second space 54. Also,
The outer surface of the second permanent magnet 30 and the free tip of the mid yoke 12 face each other via the magnetic gap 55.

When no current is applied to the first coil 14 and the second coil 16 as shown in FIG. 1, the first permanent magnet 28 → the mid yoke 12 → the second permanent magnet 30 → the core 26 → the first permanent magnet 28 is formed. In this state, the first permanent magnet 28 and the second permanent magnet 3
The zero bonding surface is located at the center of the thickness of the mid yoke 12. In the state of FIG. 1, a magnetic path 58 of the first permanent magnet 28 → the first inner yoke 20 → the core 26 → the first permanent magnet 28 is further formed, and the second permanent magnet 30 → the core 2
A magnetic path 60 of 6 → second inner yoke 22 → second permanent magnet 30 is formed.

In the state shown in FIG.
The outer surface of the first permanent magnet 28 and the first step facing surface 40 facing each other have a sufficient overlap length L1. Similarly, the outer surface of the second permanent magnet 30 facing through the magnetic gap 51 and the second step facing surface 52 have a sufficient overlap length L2. The facing length L1 and the facing length L2 are set to be the same length.

Next, from the state of FIG. 1, a current flows in the first coil 14 from the back side of FIG. 1 to the front side, and a current flows in the second coil 16 from the front side of FIG. FIG. 2 shows a state in which this current flows. Thereby, a magnetic path 62 is formed around the first coil 14 and a magnetic path 64 is formed around the second coil 16. The magnetic path 62 extends from the outer yoke 10 to the first inner yoke 2
0 → core 26 → first permanent magnet 28 → mid yoke 12 →
A loop of the outer yoke 10 is formed. The magnetic path 64
The outer yoke 10 → the second inner yoke 22 → the second permanent magnet 30 → the core 26 → the first permanent magnet 28 → the mid yoke 12 → the loop of the outer yoke 10 is formed.

When the first coil 14 and the second coil 16 are energized, the first permanent magnet 28 and the mid yoke 12 through which the magnetic paths 62 and 64 pass are attracted. Thus, a downward thrust is generated in the core 26 from the state of FIG. 1, and the core 26, the first permanent magnet 28, and the second permanent magnet 30 move downward, and the state of FIG. 2 is obtained.

In the state of FIG. 2, the second permanent magnet 30
And the second step portion facing surface 52 overlap with a sufficient length. In FIG. 2, the first permanent magnet 2
The joint surface between the second permanent magnet 8 and the second permanent magnet 30 is set to have a portion that overlaps (L3) in the radial direction with the mid yoke 12. Thereby, the magnetic path 5 shown in FIG.
6 (first permanent magnet 28 → mid yoke 12 → second permanent magnet 30 → core 26 → first permanent magnet 28) is also formed in the state of FIG. In addition, the outer peripheral surface of the first permanent magnet 28 and the first step portion opposing surface 40 are set so as to have a portion that overlaps (L4) in the radial direction. Thereby, the magnetic path 58 (first permanent magnet 28 → first inner yoke 20 → core 26 → first permanent magnet 28) shown in FIG.
Is formed also in the state of FIG. These magnetic paths 5
6 and the magnetic path 58 are formed from the state of FIG.
When the power supply to the second coil 16 is stopped, the magnetic path 56 and the magnetic path 58 return the core 26 to the state shown in FIG.

Next, a current flows in the first coil 14 from the front side to the back side in FIG. 1, and a current flows in the second coil 16 from the back side to the front side in FIG. FIG. 3 shows a state in which the current flows. Thereby, the first coil 14
A magnetic path 66 is formed around the second coil 16.
A magnetic path 68 is formed around. The magnetic path 66 is formed by the outer yoke 10 → the mid yoke 12 → the second permanent magnet 30 → the core 26 → the first permanent magnet 28 → the first inner yoke 20 →
A loop of the outer yoke 10 is formed. The magnetic path 68 is
A loop of the outer yoke 10 → the mid yoke 12 → the second permanent magnet 30 → the core 26 → the second inner yoke 22 → the outer yoke 10 is formed.

The energization of the first coil 14 and the second coil 16 attracts the second permanent magnet 30 and the mid yoke 12 through which the magnetic paths 66 and 68 pass. Thus, an upward thrust is generated in the core 26 from the state of FIG. 1, and the core 26, the first permanent magnet 28, and the second permanent magnet 30 move upward, and the state of FIG. 3 is obtained.

In the state shown in FIG. 3, the first permanent magnet 28
And the first step portion facing surface 40 overlap with a sufficient length. Also in FIG. 3, the joint surface between the first permanent magnet 28 and the second permanent magnet 30 is the mid yoke 1
2 is set so as to have a portion overlapping (L5) in the radial direction. Thus, the magnetic path 56 (first permanent magnet 28 → mid yoke 12 → second permanent magnet 30 → core 26 → first permanent magnet 28) shown in FIG. 1 is formed even in the state of FIG. Further, the outer peripheral surface of the second permanent magnet 30 and the second step portion opposing surface 52 are set to have a portion that overlaps (L6) in the radial direction. Thereby, the magnetic path 60 (second permanent magnet 30) shown in FIG.
→ core 26 → second inner yoke 22 → second permanent magnet 3
0) is formed even in the state of FIG. The formation of the magnetic path 56 and the magnetic path 60 is such that when the power supply to the first coil 14 and the second coil 16 is stopped from the state of FIG. This is for the function of returning to the state of 1.

In the present invention configured as described above, as shown in FIGS. 2 and 3, the magnetic paths 62, 64, 66, and 68 formed when the first coil 14 and the second coil 16 are energized,
It passes through the permanent magnets 28 and 30, the mid yoke 12 and the inner yokes 20 and 22, but does not pass through the coils 14 and 16. This is because the magnetic paths 62, 64, 66, 68
Is made possible through the mid yoke 12 provided between the first coil 14 and the second coil 16.
Therefore, in the present invention, the magnetic resistance is smaller than that in the conventional case where the magnetic path passes through the coil, and a decrease in the magnetic flux can be prevented. Therefore, the present invention can obtain a larger thrust than the conventional one. Here, FIG. 4 shows a comparison of the thrust between the present invention and the conventional example. FIG. 4 shows that the present invention can obtain a thrust twice or more as compared with the conventional example.

In the present invention, even in the state shown in FIGS. 2 and 3, the joint surface between the first permanent magnet 28 and the second permanent magnet 30 and the mid yoke 12 are set so as to have a portion which overlaps in the radial direction. is there. At this time, if the thickness of the mid yoke 12 is increased, the stroke of the core 26 can be increased. That is, in order to increase the stroke, the length of the pair of permanent magnets in which the magnetic poles are arranged in the axial direction had to be increased in the conventional example. You just need to make it thicker. As a result, even if the same stroke is obtained, the present invention can be made smaller than the conventional example.

In the above description, the first permanent magnet 28 and the second permanent magnet 30 are joined, but they may be attached via a thin member between them. Although the first permanent magnet 28 and the second permanent magnet 30 are cylindrical, the first permanent magnet 28 and the second permanent magnet 30 may be segment-shaped magnets.

[0025]

As described above, according to the electromagnetic linear actuator according to the present invention, the magnetic flux is prevented from being reduced by forming a magnetic path passing through the permanent magnet and the yoke, avoiding the coil. The thrust could be increased more. Further, in the present invention, the stroke of the core can be increased by increasing the thickness of the mid yoke, so that the size can be reduced compared to the conventional example in which the stroke is increased by increasing the length of the permanent magnet in the magnetic pole direction. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an electromagnetic linear actuator according to the present invention, showing a state in which no current flows through a coil.

FIG. 2 is a cross-sectional view showing a state in which a current in one direction flows through the coil from the state of FIG.

FIG. 3 is a cross-sectional view showing a state in which a current flows in the coil in the other direction from the state of FIG.

FIG. 4 is a characteristic diagram showing a relationship between stroke and thrust between the present invention and a conventional example.

FIG. 5 is a sectional view showing a conventional electromagnetic linear actuator.

[Explanation of symbols]

 Reference Signs List 10 outer yoke 12 mid yoke 14 first coil 16 second coil 20 first inner yoke 22 second inner yoke 26 core 28 first permanent magnet 30 second permanent magnet 32 gap 39 gap 43 gap 44 gap 51 gap 55 gap

Continued on the front page F term (reference) 5H633 BB08 GG02 GG04 GG13 HH03 HH05 HH13 HH27 HH28 5H641 BB06 BB14 BB19 GG02 GG12 HH03 HH05 HH07 HH14 HH19 HH20

Claims (3)

[Claims] A coil is provided inside a cylindrical outer yoke, a core is movably provided in the axial direction at a position of an axial center of the coil, and a permanent magnet is fixed outside the core.
In an electromagnetic linear actuator that reciprocates the core by energizing the coil, the coil includes a first coil and a second coil arranged at intervals in an axial direction of an outer yoke, and the first coil and the second coil are arranged. A mid yoke as a magnetic body is provided at an intermediate position between the two coils, and a first inner yoke as a magnetic body fixed to the outer yoke is provided at a position opposite to the mid yoke with respect to the first coil. A second inner yoke as a magnetic material fixed to the outer yoke at a position opposite to the mid yoke with the second coil as a center, wherein the core is formed of a magnetic material, and the first inner yoke is provided with the core. A magnetic gap is formed between the cores, and the second inner yoke forms a magnetic gap between the core and the core. The first permanent magnet and the second permanent magnet are touched or brought close to each other, the first permanent magnet and the second permanent magnet are magnetized in the radial direction, and the magnetic poles are arranged at different positions from each other. An electromagnetic linear actuator, wherein a magnetic gap is formed between the outer surface of the first permanent magnet and the outer surface of the second permanent magnet and the mid yoke. 2. The magnetic air gap between the first permanent magnet and the second permanent magnet and the mid yoke is in a radial direction regardless of whether the first coil and the second coil are energized or de-energized. 2. The electromagnetic linear actuator according to claim 1, wherein the electromagnetic linear actuator has an overlapping portion. 3. A magnetic gap in which the first permanent magnet radially overlaps with the first inner yoke in both the energized state and the de-energized state of the first coil and the second coil. 3. The electromagnetic linear actuator according to claim 1, wherein the second permanent magnet has a magnetic air gap radially overlapping the second inner yoke.