JP2015053805A - Magnetic circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic circuit improved in assembly accuracy.SOLUTION: A magnetic circuit 2 is specified as a novel magnetic circuit that can be substituted in place of an old magnetic circuit mainly composed of a sintered magnet based on a neodymium magnet. In addition to an occupation region of a sintered magnet of the old magnetic circuit, the magnetic circuit 2 includes the amount of a plastic magnet 21 based on the neodymium magnet extending over an occupation region of an inner yoke. With the magnetic circuit 2, not only a plastic magnet 21 can be obtained by injection molding using synthetic resin containing powder of neodymium, but also the plastic magnet 21 is integrally molded with an outer yoke 23 by the injection molding. Shortage of an amount of total magnetic flux in comparison with an amount of magnetic flux by the same amount of the sintered magnet is compensated by increase in the plastic magnet.

Description

  The present invention relates to a magnetic circuit formed by combining a plurality of parts including a magnet.

  Patent Document 1 discloses a configuration of a magnetic circuit including five parts including a magnet. An intermediate member is joined to the upper and lower surfaces of the magnet, an inner yoke is joined to the upper intermediate member, and an outer yoke is joined to the lower intermediate member. The gap between the inner yoke and outer yoke is called a gap. When a coil is arranged in the gap and current is supplied to the coil in the magnetic field, electromagnetic force is generated in the direction of the thumb according to Fleming's left-hand rule. The actuator is moved by the electromagnetic force, and for example, a tactile feedback function that gives a reaction force to the switch operation can be obtained.

JP-A-10-340809 (paragraphs [0034] and [FIG. 6])

  Since the coil is arranged in the gap portion, it is essential to ensure the clearance between the coil and the yoke. However, since the magnetic circuit is composed of a plurality of parts, a high accuracy is required for each part tolerance and assembly tolerance, and there is a problem that it must be cleared.

  The present invention has been made paying attention to such problems, and an object thereof is to provide a magnetic circuit capable of increasing the assembly accuracy.

  A magnetic circuit that solves the above problem is a magnetic circuit formed by combining a plurality of parts including a magnet, and a plastic magnet is integrally formed with the other parts as the magnet to form the magnetic circuit, and the same amount of sintered magnet The gist is to supplement the shortage of the total magnetic flux with respect to the amount of plastic magnets.

  According to this configuration, the assembly accuracy can be increased by integrally molding a plurality of parts including the plastic magnet. However, if the sintered magnet is simply replaced with a plastic magnet, the value of the total magnetic flux decreases in comparison with the same amount, which causes a reduction in the generated force of the actuator. In this case, the shortage of the total magnetic flux can be compensated by increasing the amount of the plastic magnet.

  With respect to the magnetic circuit, the magnetic circuit is defined as a new magnetic circuit that replaces an old magnetic circuit formed by combining a sintered magnet and an inner yoke and an outer yoke made of a magnetic material. In addition, the plastic magnet may be provided in an amount that covers the area occupied by the inner yoke.

According to this configuration, it is possible to improve the assembly accuracy by integral molding while maintaining the actuator generating force by the three-component old magnetic circuit.
Regarding the magnetic circuit, the magnetic circuit is defined as a new magnetic circuit that replaces an old magnetic circuit formed by combining a sintered magnet and an inner yoke and an outer yoke made of a magnetic material, In addition to both of the occupied areas of the inner yoke, an amount of the plastic magnet that covers a partial area of the outer yoke may be provided.

According to this configuration, it is possible to improve the assembly accuracy by integral molding while maintaining the actuator generating force by the three-component old magnetic circuit.
When a current is supplied to a coil arranged in a magnetic field generated by the magnetic circuit, the magnetic circuit is allowed to move by an electromagnetic force generated in the direction of the thumb in accordance with Fleming's left-hand rule. A shaft hole through which a mandrel that allows movement of the magnetic circuit by force may be provided.

  According to this configuration, positioning is facilitated by passing the mandrel through the shaft hole of the magnetic circuit.

  According to the present invention, the assembly accuracy can be increased.

The disassembled perspective view which shows the principal part structure of the actuator containing the magnetic circuit by 1st Embodiment. Sectional drawing which shows the structure of an old magnetic circuit. Sectional drawing which shows the orientation in an old magnetic circuit. Sectional drawing which shows the structure of the magnetic circuit by 1st Embodiment with orientation. The table | surface which compares and shows the residual magnetic flux density for every magnet. Sectional drawing which shows the structure of the magnetic circuit by 2nd Embodiment with orientation. Sectional drawing which shows the structure of the magnetic circuit by 3rd Embodiment with orientation.

(First embodiment)
Hereinafter, a first embodiment of the magnetic circuit will be described.
As shown in FIG. 1, the magnetic circuit 2 constitutes an actuator 1 together with a coil ASSY 3. The magnetic circuit 2 is defined as a new magnetic circuit that replaces the old magnetic circuit mainly composed of sintered magnets.

  As shown in FIG. 2, the old magnetic circuit 2F includes a sintered magnet 21F made of a neodymium magnet, an inner yoke 22F and an outer yoke 23F made of a magnetic material. The outer yoke 23F serving as a base has a disk-shaped bottom wall and a peripheral wall along the outer edge, and has a substantially U-shaped cross section. A sintered magnet 21F is bonded to the center of the inner bottom surface of the outer yoke 23F. The sintered magnet 21F has a disk shape that is slightly smaller than the bottom wall of the outer yoke 23F. An inner yoke 22F having a disk shape with the same diameter is bonded to the upper surface of the sintered magnet 21F. A gap between the outer peripheral surfaces of the sintered magnet 21F and the inner yoke 22F and the inner peripheral surface of the peripheral wall of the outer yoke 23F is defined as a gap 24F.

  As shown in FIG. 3, the old magnetic circuit 2 </ b> F is set to an orientation obtained in the direction of the magnetic field from the bottom to the top of the sintered magnet 21 </ b> F. The magnetic field generated by the sintered magnet 21F is guided from the inner yoke 22F to the peripheral wall of the outer yoke 23F via the gap 24F, and finally reaches the sintered magnet 21F from the bottom wall following the shape of the outer yoke 23F.

As shown in FIG. 4, the magnetic circuit 2 replaced with the old magnetic circuit 2F includes a plastic magnet 21 made of a neodymium magnet in an amount extending to the occupied area of the inner yoke 22F in addition to the occupied area of the sintered magnet 21F of the old magnetic circuit 2F. It has. In the magnetic circuit 2, the plastic magnet 21 is obtained by injection molding using a synthetic resin containing neodymium powder, and the plastic magnet 21 is integrally formed with the outer yoke 23 equivalent to the outer yoke 23F by the injection molding. A gap between the outer peripheral surface of the plastic magnet 21 and the inner peripheral surface of the peripheral wall of the outer yoke 23 is defined as a gap 24 equivalent to the gap 24F. The magnetic circuit 2 is set to have an orientation in which the direction of the magnetic field is obtained from the bottom to the top near the radial center of the plastic magnet 21 and the direction of the magnetic field is obtained from the inside to the outside at the top of the plastic magnet 21. ing. The magnetic field generated by the plastic magnet 21 is guided from the outer periphery of the plastic magnet 21 to the peripheral wall of the outer yoke 23 via the gap 24, and finally reaches the plastic magnet 21 from the bottom wall following the shape of the outer yoke 23.

  As shown in FIG. 5, when the residual magnetic flux density for each magnet is compared, the value of the neodymium magnet (plastic magnet 21) by bond is smaller than that of the neodymium magnet by sintering (sintered magnet 21F). That is, if the sintered magnet is simply replaced with a plastic magnet, the value of the total magnetic flux decreases in comparison with the same amount. For this reason, in this example, in addition to the occupied area of the sintered magnet 21F of the old magnetic circuit 2F, the amount of the plastic magnet 21 extending to the occupied area of the inner yoke 22F is used. Thereby, the shortage of the total magnetic flux amount with respect to the same amount of sintered magnet is compensated by the increase amount of the plastic magnet. In addition to the distribution of the magnets derived from the amount of the plastic magnets 21, the orientation of the plastic magnets 21 compensates for the shortage of the total magnetic flux amount for the same amount of sintered magnets.

  Returning to FIG. 1, the coil ASSY 3 mainly includes the coil 32 wound around the bobbin 31. The inner diameter of the bobbin 31 is slightly larger than the outer diameter of the plastic magnet 21, and the outer diameter of the coil 32 is slightly smaller than the inner diameter of the peripheral wall of the outer yoke 23. As a result, the coil 32 is arranged in the gap 24 with a clearance between the bobbin 31 and the plastic magnet 21 and between the coil 32 and the peripheral wall of the outer yoke 23. When a current is supplied from a current source (not shown) to the coil 32 in the magnetic field, an electromagnetic force is generated in the direction of the thumb according to Fleming's left-hand rule.

  Referring to FIG. 4, in the vicinity of the left gap 24, the direction of the magnetic field is a direction from right to left, so that the direction of the current supplied to the coil 32 is a direction from the front to the back of the page. Assuming that, electromagnetic force is generated in the direction from bottom to top. On the other hand, in the vicinity of the right gap 24, the direction of the magnetic field is the direction from left to right, and the direction of the current supplied to the coil 32 is the direction from the back to the front of the page based on the above assumption. Therefore, an electromagnetic force is generated in the same direction from the bottom to the top. As a result, the magnetic circuit 2 and the coil ASSY 3 relatively linearly move up and down by the electromagnetic force. For example, in the configuration in which the magnetic circuit 2 can be displaced while the coil ASSY 3 is fixed, the magnetic circuit 2 performs a downward movement from the top to the bottom in a manner against the direction of the electromagnetic force from the bottom to the top. On the other hand, in the configuration in which the coil ASSY 3 can be displaced while the magnetic circuit 2 is fixed, the coil ASSY 3 moves upward from the bottom in a manner that follows the direction of the electromagnetic force from the bottom to the top.

Next, the operation of the magnetic circuit 2 will be described.
The magnetic circuit 2 is formed by integrally molding a plastic magnet 21 and an outer yoke 23 by injection molding. For this reason, even if the assembling accuracy depends on the dimensional tolerance of the molding die, high accuracy can be easily cleared as compared with the old magnetic circuit 2F in which a plurality of components are individually manufactured and each component is assembled by bonding. As a result, the gap 24 in which the coil 32 is disposed is optimized, and a necessary and sufficient clearance is ensured between the coil 32 and the coil 32.

As described above, according to the first embodiment, the following effects can be obtained.
(1) By integrally molding a plurality of parts including the plastic magnet 21, assembly accuracy can be increased.

  (2) The magnetic circuit 2 includes the plastic magnet 21 in an amount extending over the area occupied by the inner yoke 22F in addition to the area occupied by the sintered magnet 21F. Therefore, the assembly accuracy can be increased by integral molding while maintaining the actuator generating force by the old magnetic circuit 2F having the three-part configuration.

  (3) The plastic magnet 21 made of neodymium magnet was integrally formed with other parts to form the magnetic circuit 2, and the shortage of the total magnetic flux with respect to the same amount of sintered magnet was compensated by the increase in the plastic magnet. Therefore, the assembly accuracy can be improved by integral molding, and the generated force of the actuator 1 can be made equivalent to that of the old magnetic circuit 2F using the sintered magnet 21F.

(4) The actuator generation force can be maintained by the distribution and orientation of the plastic magnet 21.
(Second Embodiment)
Next, a second embodiment of the magnetic circuit will be described.

  As shown in FIG. 6, the magnetic circuit 2A is defined as a new magnetic circuit that replaces the old magnetic circuit 2F. The magnetic circuit 2A includes a plastic magnet 21A made of a neodymium magnet in an amount extending over a partial region of the outer yoke 23F, in addition to both the occupation region of the sintered magnet 21F and the occupation region of the inner yoke 22F. That is, the plastic magnet 21 </ b> A occupies a partial region of the peripheral wall of the outer yoke 23 in addition to the region occupied by the plastic magnet 21 according to the first embodiment. The magnetic circuit 2A is integrally formed by injection molding. For convenience, an area equivalent to the outer yoke 23 including the area occupied by the plastic magnet 21A is defined as the outer yoke 23A. A gap 24A equivalent to the gap 24 is also defined. Of the peripheral wall of the outer yoke 23A, the portion occupied by the plastic magnet 21A is set to the orientation in which the direction of the magnetic field is obtained from the top to the bottom. As a result, the magnet is increased with the addition of the above-mentioned part, and the shortage of the total magnetic flux with respect to the same amount of the sintered magnet is compensated by the orientation of the part, and the actuator is higher than in the first embodiment. Generating power is obtained.

As described above, according to the second embodiment, in addition to the same effects as the effects (1) to (4) according to the first embodiment, the following effects can be achieved.
(5) The magnetic circuit 2A includes the plastic magnet 21A in an amount extending over a partial region of the outer yoke 23F in addition to both the occupied region of the sintered magnet 21F and the occupied region of the inner yoke 22F. Therefore, the assembly accuracy can be increased by integral molding while maintaining the actuator generating force by the old magnetic circuit 2F having the three-part configuration.

(Third embodiment)
Next, a third embodiment of the magnetic circuit will be described.
As shown in FIG. 7, the magnetic circuit 2B has an outer shape equivalent to that of the old magnetic circuit 2F, and includes a shaft hole 20B penetrating in the vertical direction at the radial center. A mandrel (not shown) provided in the coil ASSY 3 and disposed at the center in the radial direction of the bobbin 31 is passed through the shaft hole 20B. Thereby, the movement of the magnetic circuit 2B or the coil ASSY3 by the electromagnetic force is allowed. The magnetic circuit 2B includes a region excluding the region of the shaft hole 20B from the region corresponding to the three regions of the occupied region of the sintered magnet 21F, the occupied region of the inner yoke 22F, and a partial region of the bottom wall of the outer yoke 23F, There is provided a plastic magnet 21B made of a neodymium magnet in an amount extending over a partial region of the peripheral wall of the outer yoke 23F. That is, the plastic magnet 21B occupies the area excluding the area of the shaft hole 20B from the area corresponding to both the occupied area of the plastic magnet 21A according to the second embodiment and the partial area of the bottom wall of the outer yoke 23A. . Magnetic circuit 2
B is integrally formed by injection molding. For convenience, an area equivalent to the outer yoke 23 including the area occupied by the plastic magnet 21B is defined as the outer yoke 23B. A gap 24B equivalent to the gap 24 is also defined. In the portion occupied by the plastic magnet 21B in the bottom wall of the outer yoke 23B, the direction of the magnetic field is obtained from the outside to the inside, and the orientation is set such that the direction of the magnetic field is obtained from the bottom to the top. . As a result, the shortage of the magnet amount due to the shaft hole 20B is compensated with the addition of the above portion, and the shortage of the total magnetic flux amount with respect to the same amount of sintered magnet is also compensated by the orientation of the portion. An actuator generating force equivalent to that of the embodiment can be obtained.

As described above, according to the third embodiment, in addition to the same effects as the effects (1) to (5) according to the above embodiments, the following effects can be achieved.
(6) Positioning is facilitated by passing the mandrel through the shaft hole 20B of the magnetic circuit 2B.

It should be noted that each of the above embodiments can be modified and embodied as follows.
-About 3rd Embodiment, you may omit the plastic magnet 21B of the surrounding wall of the outer yoke 23B. In this case, an actuator generating force equivalent to that of the first embodiment can be obtained.

  As a new magnetic circuit that replaces the old magnetic circuit 2F mainly composed of the sintered magnet 21F made of a neodymium magnet, it may be embodied as a magnetic circuit mainly made of a plastic magnet made of a samarium iron magnet.

  As shown in FIG. 5, the value of the residual magnetic flux density of the samarium iron magnet (plastic magnet) by bonding is smaller than that of the neodymium magnet (sintered magnet 21F) by sintering. That is, simply replacing the sintered neodymium magnet with a samarium iron magnet made of bond will reduce the value of the total magnetic flux in the same amount of comparison. Therefore, following the above embodiments, a plastic magnet made of samarium iron magnet is integrally molded with other parts to form a magnetic circuit, and the shortage of the total magnetic flux with respect to the same amount of sintered magnet is increased by the increase of the plastic magnet. It is possible to replace the old magnetic circuit 2F by making up for this.

  According to this configuration, the assembling accuracy is improved by integral molding, and the generation force of the actuator can be made equal to that of the old magnetic circuit using the sintered magnet, and the weight can be reduced. In the case of a samarium iron magnet, the specific gravity is about 1/4 that of iron.

Next, technical ideas that can be grasped from the above embodiments and other examples will be described.
(B) In a magnetic circuit, the magnetic circuit is defined as a new magnetic circuit that replaces an old magnetic circuit formed by combining a plurality of parts including sintered magnets made of neodymium magnets, and plastic magnets made of neodymium magnets are replaced with other parts. And the magnetic circuit was formed as a single piece, and the shortage of the total magnetic flux for the same amount of sintered magnet was compensated by the increase in the amount of plastic magnet.

According to this configuration, the assembly accuracy can be increased by integral molding, and the generated force of the actuator can be made equivalent to that of the old magnetic circuit using the sintered magnet.
(B) In the magnetic circuit, the magnetic circuit is defined as a new magnetic circuit that replaces the old magnetic circuit formed by combining a plurality of parts including sintered magnets made of neodymium magnets, and plastic magnets made of samarium iron magnets. The shortage of the total magnetic flux for the same amount of sintered magnet was compensated by the increase in plastic magnet while forming the magnetic circuit integrally with the parts.

According to this configuration, the assembling accuracy is improved by integral molding, and the generation force of the actuator can be made equal to that of the old magnetic circuit using the sintered magnet, and the weight can be reduced. In the case of a samarium iron magnet, the specific gravity is about 1/4 that of iron.

  (C) In the magnetic circuit, the shortage of the total magnetic flux with respect to the same amount of sintered magnets should be compensated by both the distribution of magnets derived from the amount of plastic magnets and the orientation of magnets derived from the direction of the magnetic field.

  According to this configuration, the actuator generating force can be maintained by the distribution and orientation of the magnets.

  DESCRIPTION OF SYMBOLS 1 ... Actuator, 2A, 2B ... Magnetic circuit, 3 ... Coil ASSY, 20B ... Shaft hole, 21, 21A, 21B ... Plastic magnet (magnet), 23, 23A, 23B ... Outer yoke, 24, 24A, 24B ... Gap, 31 ... bobbin, 32 ... coil.

Claims (4)

In a magnetic circuit formed by combining a plurality of parts including a magnet,
A magnetic circuit characterized in that a plastic magnet is integrally formed with other parts as the magnet to form the magnetic circuit, and an insufficient amount of the total magnetic flux with respect to the same amount of sintered magnet is compensated by an increase of the plastic magnet. The magnetic circuit is defined as a new magnetic circuit that replaces an old magnetic circuit formed by combining a sintered magnet and an inner yoke and an outer yoke made of a magnetic material.
The magnetic circuit according to claim 1, further comprising an amount of the plastic magnet extending to an area occupied by the inner yoke in addition to the area occupied by the sintered magnet. The magnetic circuit is defined as a new magnetic circuit that replaces an old magnetic circuit formed by combining a sintered magnet and an inner yoke and an outer yoke made of a magnetic material.
2. The magnetic circuit according to claim 1, comprising an amount of the plastic magnet extending to a partial region of the outer yoke in addition to both the occupied region of the sintered magnet and the occupied region of the inner yoke. When a current is supplied to a coil arranged in a magnetic field generated by the magnetic circuit, the movement is allowed by the electromagnetic force generated in the direction of the thumb according to Fleming's left-hand rule, or the magnetic circuit The magnetic circuit as described in any one of Claims 1-3 provided with the axial hole through which the mandrel which accept | permits the motion of this.