JPH0794323A - Equivalent poleless bidirectional linear solenoid with permanent magnet - Google Patents

Abstract

(57) [Summary] [Objective] It is an object to provide a bidirectional linear solenoid with a permanent magnet that operates equivalently to a non-polar type. [Structure] A cylindrical magnet 11 is magnetized to north and south poles in a radial direction at a substantially central portion of a shaft 12 that can move left and right.
To form a plunger portion 10, and cylindrical poles 15 and 16 are arranged on the outer periphery of the plunger portion 10 via a gap 19 having a gap length l. The inner circumference of the cylindrical poles 15 and 16 and the plunger Magnetic gaps 17 and 18 having a gap length δ are formed between the outer periphery of the portion 10. [Effect] The position of the cylindrical magnet 11 is from x> l / 2 to x
Even if it moves to <(L-1 / 2), the attraction force of the plunger portion 10 to the cylindrical poles 15 and 16 is balanced, and no attraction force acts on the plunger portion 10, so that it is equivalently non-polar. Has the effect of becoming a state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional linear solenoid having a permanent magnet, which operates equivalently to a non-polar type.

[0002]

2. Description of the Related Art Conventionally, a bidirectional linear solenoid is used to change the direction of energization to a coil, move the plunger left and right, and when the energization is cut off, the plunger does not have a holding force and is in a free state. A nonpolar bidirectional linear solenoid is disclosed in Japanese Patent Application Laid-Open No. 4-287902 (Japanese Patent Application No. 2-327).
No. 635) nonpolar bidirectional linear solenoid.

[0003]

However, since this is characterized in that the permanent magnet is not used and is made non-polar, the bidirectional linear solenoid which is equivalently non-polarized even if the permanent magnet is used. Has not been realized yet.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to provide a bidirectional linear solenoid that uses a permanent magnet and is equivalently non-polar. That is, the cylindrical magnet 11 magnetized to the north and south poles in the radial direction is fixed to substantially the center of the shaft 12 that can move to the left and right, and the plunger portion 10
And the outer circumferences of the side yokes 13 and 14 made of a soft magnetic material, in which the cylindrical poles 15 and 16 project and face each other, are fixed to the outer circumference of the plunger portion 10 by a yoke 20 made of a soft magnetic material. . Thus, the cylindrical pole 15
And a gap 19 having a gap length 1 between the protruding end faces of 16 and
The inner circumference of the cylindrical poles 15 and 16 and the plunger portion 10
This is because the magnetic gaps 17 and 18 having the gap length δ are formed between the outer circumference and the outer circumference.

[0005]

When the coil 24 is not energized, the cylindrical pole 1
5 and 16 and the suction force acting between the plunger portion 10 cause the plunger portion 10 to move to the cylindrical poles 15 and 16 respectively.
It acts to suck inside.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings will be described in detail below. Figure 1
FIG. 2 is a sectional side view of an equivalent non-polar bidirectional linear solenoid having a permanent magnet of the present invention, and FIG. In FIGS. 1 and 2, 11 is, for example, neodymium (N
d), a cylindrical magnet having a relatively large coercive force, such as an anisotropic sintered magnet containing iron (Fe) and boron (B) as the main components, is anisotropic in the radial direction, and is magnetized. There is. That is, N,
S is the magnetic pole. Reference numeral 12 denotes a shaft made of a non-magnetic material or a magnetic material, and the cylindrical magnet 11 is fixed to the outer periphery of the substantially central portion thereof by means such as bonding to form the plunger portion 10. Reference numerals 13 and 14 denote side yokes made of a soft magnetic material. Cylindrical poles 15 and 16 are made to face each other and project, and a void 19 having a void length 1 is formed between the projecting end faces. The inner circumferences of the cylindrical poles 15 and 16 are opposed to the cylindrical magnet 11 of the plunger portion 10 via magnetic air gaps 17 and 18, respectively, to form a magnetic air gap length δ. 20
Is a yoke made of a soft magnetic material, and side yokes 13 and 1
The outer periphery of 4 is fixed by means such as caulking. 21,21
Is a bearing case made of non-magnetic material, 22 and 22 are linear ball bearings, and both end portions 2 of the shaft 12 are
The shaft 12 can be slid while supporting the magnets 3 and 23 and maintaining the magnetic gap length δ. 24 is a coil wound around the cylindrical poles 15 and 16;
Is a lead wire of the coil 24. Figure 3 shows Shaft 1
When 2 is a non-magnetic material, it is the figure which showed the situation where the magnetic force line of each part passes, and the code | symbol of each part is the same as FIG.1 and FIG.2. In FIG. 3, a solid arrow indicates a pattern through which magnetic force lines generated by the cylindrical magnet 11 pass, and a dotted arrow indicates the coil 24.
FIG. 4 shows a pattern of magnetic force lines generated when a direct current is applied in the directions shown in FIGS. 1 and 3. In the state of FIG. 3, if the magnetic potential of the outer circumference of the cylindrical magnet 11 is Φ, the magnetic flux density B due to the cylindrical magnet 11 in the magnetic gaps 17 and 18 is B.
Is as in equation 1.

[0007]

[Equation 1]

The attraction force acting on the cylindrical magnet 11 of the plunger portion 10 is the magnetic flux density in the magnetic gaps 31 and 32 between the tips of the cylindrical poles 15 and 16 and the cylindrical magnet 11, respectively B ₃₁ and B _32. And the outer diameter of the plunger portion 10, that is, the outer diameter of the cylindrical magnet 11 is D (D ≧ δ) and the proportional constant is K ₁ , and in the magnetic gap 31, Φ ₃₁ is replaced by the magnetic gap 31.
As the magnetic potential of the cylindrical magnet 11 at, the force of the formula 2 acts so as to attract the plunger portion 10 into the cylindrical pole 15 (leftward in FIG. 3), and in the magnetic gap 32, Φ ₃₂ becomes the magnetic gap 32. As the magnetic potential of the cylindrical magnet 11 at, the force of the equation 3 works so as to attract the plunger portion 10 into the cylindrical pole 16 (to the right in FIG. 3).

[0009]

[Equation 2]

[0010]

[Equation 3]

Next, in FIGS. 1 and 3, when a direct current i is applied to the coil 24 in the direction shown in the drawing, a magnetomotive force H _i shown in Equation 4 is generated, where N is the number of windings of the coil 24.

[0012]

[Equation 4]

If the magnetic permeability of the yoke 20 and the side yokes 13 and 14 is sufficiently larger than that of air, and the magnetic resistance of the magnetic circuit from the cylindrical poles 16 to 15 is R _i , the recoil permeability of the cylindrical magnet 11 will be described. Since the magnetic susceptibility of the above-mentioned material is μ _r ≈1.05, which is almost the same as that of air, it can be assumed that R _i is constant regardless of the position of the cylindrical magnet 11. If the magnetic flux densities due to the direct current i in the magnetic gaps 31 and 32 are b ₃₁ and b ₃₂ , respectively, the proportional constant is K
_{2 is the same} as the number 5.

[0014]

[Equation 5]

In the magnetic gap 31, B ₃₁ and b ₃₁ are added, and in the magnetic gap 32, B ₃₂ and b ₃₂ are subtracted, so that the force acting to move the plunger portion 10 to the left in the figure is positive. As a result, the total suction force F _t is as shown in Formula 6.

[0016]

[Equation 6]

When the direction of the direct current i is converted, B ₃₁ and b ₃₁ are subtracted in the magnetic air gap 31, B ₃₂ and b ₃₂ are added in the magnetic air gap 32, and the plunger portion 10 is moved to the right in the figure. The force −F _t shown in Formula 7 that acts to act is exerted.

[0018]

[Equation 7]

That is, the solenoid shown in FIG. 1 operates as a bidirectional linear solenoid. FIG. 4 shows the plunger unit 1.
0 is a front view showing another embodiment of No. 0, and the reference numerals are the same as those in FIG. In the figure, the cylindrical magnet 11 of the plunger portion 10 is divided into four equal parts in the circumferential direction, generally n (n ≧ 2). 5 and 6 are a side sectional view and a front view showing another embodiment of the plunger portion 10. In the figure, 12 is a shaft, 41 is a cylindrical magnet, and 42 is a cylinder made of a soft magnetic material, which is fixed to the outer periphery of the cylindrical magnet 41 by means such as adhesion to form the plunger portion 10. Further, in the structures of FIGS. 5 and 6, the cylindrical magnet 41 may be divided into n (n ≧ 2) equal parts in the circumferential direction.

[0020]

The magnetic potential .PHI. On the outer circumference of the cylindrical magnet 11 can be magnetized substantially constant except for the vicinity of both end surfaces by appropriately selecting the magnetizing method. If the length of the cylindrical magnet 11 is L and the distance from the center plane Y-Y of the cylindrical poles 15 and 16 to the right end of the cylindrical magnet 11 is x, then x≈l / 2
And x> l / 2 to x except near x≈ (L-1 / 2)
Even if it moves to <(L-1 / 2), B ₃₁ ≈B ₃₂ . Therefore, during this period, the attraction force F ₃₁ expressed by the equation 2 and the attraction force F ₃₂ expressed by the equation 3 are balanced, and the plunger portion 1
No suction force works on 0. That is, there is an effect that the plunger portion 10 is equivalently brought into a nonpolar state. When the cylindrical magnet 11 is x ≦ l / 2, especially x≈l / 2, the force for moving the cylindrical magnet 11 to the right in FIGS. 1 and 3 becomes abnormally large, and x ≧ (L−l / 2) Especially x≈ (L-
1/2), the force for moving the cylindrical magnet 11 to the left in FIGS. 1 and 3 becomes abnormally large. Figure 7
The horizontal axis x, vertical axis as _{F t,} a diagram illustrating a relationship _{F t} and x, the positive direction of _{F t} is 1 and 3 the plunger portion 10
Is a force that works to move to the left. The solid line F _t in FIG. 7 represents the attractive force generated when the coil 24 is not energized, that is, only by the cylindrical magnet 11.
Further, in FIG. 7, the attraction force when a DC current of + i and a current of −i are applied to the coil 24 is also shown by a dotted line. When the cylindrical magnet 11 has a ring shape as shown in FIG. 2,
In order to magnetize as shown in the figure, a special magnetizing jig is required, but if it is divided into n (n ≧ 2) as shown in FIG. 4, it can be easily magnetized by an ordinary magnetizer. effective. The magnetic field Φ of the outer circumference of the cylindrical magnet 11 can be magnetized substantially constant except for the vicinity of both end surfaces by appropriately selecting the magnetizing method, but the magnetic field Φ due to variations in the material inside the magnet, etc. It may be difficult to completely eliminate the variation in Φ. In such a case, when the outer circumference of the cylindrical magnet 41 is covered with a cylinder 42 of a soft magnetic material having a large magnetic permeability as shown in FIGS.
Has the effect that the surface magnetic potential of is constant except for the vicinity of both end faces.

[Brief description of drawings]

FIG. 1 is a side sectional view of an equivalent nonpolar bidirectional linear solenoid having a permanent magnet of the present invention.

FIG. 2 is a sectional view taken along the arrow in FIG.

FIG. 3 is a diagram showing a situation in which a magnetic line of force of each portion passes when the shaft 12 is made of a non-magnetic material.

FIG. 4 is a front view showing another embodiment of the plunger portion 10.

FIG. 5 is a side sectional view showing another embodiment of the plunger portion 10.

FIG. 6 is a front view showing another embodiment of the plunger section 10.

FIG. 7 is a diagram showing a relationship between F _t and x.

[Explanation of symbols]

 10 Plunger part 11 Cylindrical magnet 12 Shaft 13,14 Side yoke 15,16 Cylindrical pole 17,18 Magnetic air gap 19 Air gap 20 Yoke 22,22 Linear ball bearing 24 Coil 31,32 Magnetic air gap 41 Cylindrical magnet 42 Cylindrical

Claims (3)

[Claims] 1. A cylindrical magnet 1 which is magnetized into N and S poles in a semi-phantom direction at a substantially central portion of a shaft 12 which is movable left and right.
The side yoke 13 is made of a soft magnetic material. The side yoke 13 is made of a soft magnetic material.
The outer circumferences of and 14 are fixed by a yoke 20 made of a soft magnetic material. Thus, a void 19 having a void length 1 is formed between the protruding end faces of the cylindrical poles 15 and 16, and the cylindrical poles 15 and 1
The gap length δ between the inner circumference of 6 and the outer circumference of the plunger portion 10
Magnetic gaps 17 and 18 of
Equivalent poleless bidirectional linear solenoid with permanent magnet. 2. The permanent magnet according to claim 1, wherein the cylindrical magnet 11 of the plunger portion 10 is divided into n (n ≧ 2) equal parts in the circumferential direction. Has an equivalent non-polar bidirectional linear solenoid. 3. The permanent magnet according to claim 1, characterized in that the plunger part (10) is constituted by fixing a cylinder (42) made of a soft magnetic material to the outer circumference of a cylindrical magnet (41). , Equivalent nonpolar bidirectional linear solenoid.