JPS5915448Y2 - magnetic circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to improvements in magnetic circuits used for vibration exciters and motors.

Conventionally, this type of magnetic circuit, as shown in Figs. 1 and 2, consists of a soft magnetic cylindrical pole piece 2 having a disk-shaped yoke 1 at the bottom, and a ring magnetized in the radial direction disposed outside of the soft magnetic cylindrical pole piece 2. A permanent magnet 3 having a shape of
It consists of a cylindrical yoke 4 whose lower inner circumferential surface is connected to the outer circumferential surface of a disk-shaped yoke 1 and which accommodates a permanent magnet.

Then, a radial magnetic field is formed in the cylindrical gap 5 between the inner peripheral surface of the permanent magnet 3 and the outer peripheral surface of the cylindrical pole piece 2, and the cylindrical magnetic pole piece 2, the disc-shaped yoke 1, and the cylindrical yoke 4 are Through this, a magnetic retention path is formed that reaches the permanent magnet 3.

It is well known that 6 is a moving coil placed in the air gap 5, and that the electromagnetic action of the current flowing inside the coil and the magnetic field formed in the air gap generates and utilizes a driving force in the axial direction of the coil. It is as follows.

Such devices are often used for driving magnetic disk devices and magnetic heads, and recently there has been a demand for devices with particularly high speed, high responsiveness, and high stability.

Therefore, a large current is applied to the moving coil 6, and the air gap 5
Magnetic circuits with high magnetic flux density have been used.

However, in the conventional magnetic circuit described above, the outer periphery of the permanent magnet 3 is surrounded by the cylindrical yoke 4, so the cooling effect of the magnet is extremely poor, and the temperature of the magnet rises due to the heat generated by the moving coil 6 due to energization. The magnetic flux density of the air gap 5 varies greatly depending on the temperature coefficient of the air gap 5, which affects the stability and reliability of the driving force.

Furthermore, the above-mentioned permanent magnet 3 is usually divided into two parts in the circumferential direction.
In order to use a combination of more than one fan-shaped permanent magnet 3',
It is difficult to magnetize the fan-shaped permanent magnet 3' after it is assembled into a circuit, and it is also not easy to magnetize the sector-shaped permanent magnet 3' in the radial direction and to incorporate it into the circuit.

In order to solve the above-mentioned problems, this invention aims to create a magnetic circuit that stably improves the driving force with excellent heat dissipation, and is easy to magnetize and assemble. Intended for circuits.

That is, in the above-mentioned magnetic circuit, this invention consists of a cylindrical magnetic pole piece with a plate-shaped yoke connected to the bottom surface, and a cylindrical magnetic pole piece that is made of a regular polygon and has a circular hole that can be loosely inserted by forming a gap around the outer periphery of the cylindrical magnetic pole piece. A regular polygonal columnar magnetic pole piece arranged coaxially with the magnetic pole piece, a permanent magnet magnetized in the plate thickness direction attached to each side with an adjacent gap in the circumferential direction of the regular polygonal columnar magnetic pole piece, and a plate-shaped permanent magnet. This is a magnetic circuit consisting of a plate-shaped yoke of a cylindrical pole piece attached to the outer side surface and a yoke connected to the cylindrical pole piece.

This idea involves loosely inserting a cylindrical pole piece into the inner hole of a regular polygonal pole piece with a gap, and attaching plate-shaped permanent magnets magnetized in the thickness direction to each side of the outer periphery of the regular polygonal pole piece. Permanent magnets are arranged in layers around the outer periphery of a cylindrical pole piece that is connected to a plate-shaped yoke.

Therefore, a magnetic circuit can be constructed without using permanent magnets magnetized in the radial direction as in the past, and assembly is easy.Moreover, the plate-shaped permanent magnets, which are easy to magnetize, are placed in the circumferential direction of the regular polygonal pole piece. Since they are attached to each side with a gap, heat radiation is not hindered even when the outer yoke is connected to each plate-shaped permanent magnet, which has the advantage of stably improving the driving force.

This invention will be explained in detail below based on drawings of embodiments.

The embodiment of this invention shown in FIGS. 3 and 4 shows a case where a regular hexagonal pole is used as the regular polygonal pole piece, and a rectangular plate is used as the outer yoke.

The cylindrical magnetic pole piece 2 is arranged upright in the center of the regular hexagonal plate-shaped yoke 11.

The regular hexagonal columnar magnetic pole piece 8 is a regular hexagonal columnar body provided with a circular hole 7 in the center into which the cylindrical magnetic pole piece 2 can be loosely inserted with a predetermined gap 5 provided therebetween.

The plate-shaped permanent magnet 13 is a rectangular permanent magnet magnetized in the direction of its plate thickness.

Further, the outer yoke 14 is larger than the plate-shaped permanent magnet 13.
It is composed of rectangular plates.

In the magnetic circuit, a regular hexagonal pole piece 8 is coaxially arranged around a cylindrical pole piece 2, and plate-shaped permanent magnets 13 are attached to each side surface 9 of the outer periphery of the regular hexagonal pole piece 8. A predetermined gap a is provided between the plate-shaped permanent magnets 13 on the side surface 9, outer yokes 14 are arranged and fixed on the outer surfaces 10 of the plate-shaped permanent magnets 13, and the lower part 15' of each outer yoke 14 is Hexagonal plate yoke 1
The moving coil 6 is inserted into the gap 5 formed in the circular hole 7 of the regular hexagonal pole piece 8. There is.

The magnetic circuit in the above embodiment uses a hexagonal columnar magnetic pole piece with a plate-shaped permanent magnet divided into six sections and a plate-shaped yoke, instead of the conventional ring-shaped permanent magnet and the cylindrical yoke that closely surrounds the ring-shaped permanent magnet. Cooling gaps a and a' are provided between the adjacent plate-shaped permanent magnets and between the plate-shaped yokes. This further improves the characteristics of the driving force by suppressing changes in the magnetic flux density of the magnet.

In the embodiment, the magnetic pole piece is described as having a regular hexagonal column shape, but it goes without saying that it can be made into any regular polygonal column, and that a wide variety of yoke shapes can be used.

In addition, since rectangular magnets are used, the magnetization of these plate magnets can be done in the direction parallel to the thickness. There is no need to use a magnet, and even with the same magnet length, it can be carried out more easily with less magnetizing force.

Furthermore, since a high-performance magnetic circuit requires a large magnetizing force, for example when rare earth magnets are used, the magnetic circuit of this invention is more advantageous, and furthermore, the assembly of the magnetic circuit is much easier than the conventional one. Become.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of a conventional magnetic circuit, Fig. 2 is a plan view thereof, Fig. 3 is a longitudinal sectional front view of the magnetic circuit of this invention, Fig. 4 is a plan view thereof, and Fig. 5 is a rectangular plate. FIG. 3 is a perspective view of a shaped permanent magnet and a yoke portion. In the figure, 2...Cylindrical magnetic pole piece, 5...Gap, 7...Circular hole, 8...Regular hexagonal columnar magnetic pole piece, 11...・Regular hexagonal plate yoke, 14・・・・・・
Outer yoke, 13...Plate permanent magnet, aa'...
····gap.

Claims (1)

[Scope of utility model registration request] A magnetic circuit in which a magnetic field in the radial direction is formed in the gap by permanent magnets arranged in layers with a cylindrical magnetic pole piece forming an air gap around the outer periphery of the cylindrical magnetic pole piece, a cylindrical magnetic pole piece having a plate-shaped yoke connected to the bottom surface; A regular polygonal pole piece that is made of a regular polygonal prism, has a circular hole that can be loosely inserted by forming a gap around the outer periphery, and is arranged coaxially with the cylindrical pole piece, and a gap adjacent to the regular polygonal pole piece in the circumferential direction. It consists of a plate-shaped permanent magnet magnetized in the thickness direction, which is attached to each side of the plate, and a yoke which is attached to the outer side of the plate-shaped permanent magnet and connected to the plate-shaped yoke of the cylindrical pole piece magnetic circuit.