JPH0429303A - Tubular multipolar permanent magnet - Google Patents

Abstract

PURPOSE:To use an easy-to-process component, to reduce the number of assembly and to reduce cogging torque without requiring a magnetic pole of a complicated configuration by providing grooves corresponding to the number of magnetic poles in an outer peripheral surface of a tubular permanent magnet. CONSTITUTION:Multipolar magnet is realized in an outer peripheral surface of a tubular permanent magnet which has a shaft for rotation at a center of a tubular permanent magnet 1, or has a tubular component composed of a soft magnetic material or a component of non-magnetic material in an inner peripheral surface and consists of a shaft. Grooves 2 corresponding to magnetic poles are provided to an outer peripheral surface. Thereby, it is possible to use an easy-to-process component and to manufacture a single phase synchronous motor of reduced assembly manhours and a dc motor of reduced cogging torque without requiring magnetic pole of complicated shape as a conventional one.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a cylindrical multi-polar magnetized permanent magnet used in the rotor of a single-phase synchronous motor that rotates only in a specific direction or a DC motor with reduced cogging torque. Regarding.

[Prior Art] Conventional single-phase synchronous motors using cylindrical multi-pole magnetized permanent magnets are known, such as those made in Japanese Patent Publication No. 1983-1983, in which the magnetic poles of the stator are shaped like sawtooth teeth to rotate in a specific direction. Ta.

In addition, in DC motors in which permanent magnets are bonded together for each magnetic pole to form a rotor, magnetic flux concentrates on adjacent permanent magnet parts and cogging torque increases, so it is necessary to create gaps between adjacent parts or chamfer the permanent magnets. They were made to form a groove shape when bonded together.

[Problems to be Solved by the Invention] However, the method according to the prior art as described above has a problem in that processing is difficult in manufacturing the magnetic pole shape of a stator having a complicated shape.

Furthermore, the bonding method has the problem that it takes a lot of man-hours to assemble the rotor.

Therefore, the present invention is intended to solve these problems, and its purpose is to use components that can be easily machined and to eliminate the need for magnetic poles with complicated shapes as in the past. Another object of the present invention is to provide a cylindrical multipolar magnetized permanent magnet that can be used to manufacture a single-phase synchronous motor with reduced assembly man-hours and a DC motor with reduced cogging torque.

[Measures for Solving the Problems 8] In order to solve the above problems, the cylindrical multipolar magnetized permanent magnet of the present invention has an axis for rotation in the center of the cylindrical permanent magnet, or A cylindrical multi-polar magnet, which has a cylindrical component made of a soft magnetic material or a component made of a non-magnetic material, and has a shaft and is magnetized with multiple poles on the outer peripheral surface of the cylindrical permanent magnet. The magnetic permanent magnet is characterized by having grooves in the number corresponding to the number of magnetized poles on the outer circumferential surface.

[Example] Embodiments of the present invention will be described below based on the drawings.

Nd - commonly called resin bonded rare earth permanent magnet
A cylindrical permanent magnet having an outer diameter of 18 mm and an inner diameter of 15 mm was obtained by extruding a mixture of Fe-based (neodymium iron) permanent magnet powder and a thermosetting epoxy resin as a binder using an extrusion molding device.

The extrusion mold is provided with 10 equally spaced convex protrusions, and 10 grooves with a U-shaped cross section are simultaneously formed on the outer peripheral surface of the molded cylindrical permanent magnet.

In this example, amorphous flake-like permanent magnet powder was used, but SmCo-based (samaryum cobalt) powder was used.
By molding permanent magnet powder using a magnetic field extrusion molding device that generates a radial orienting magnetic field, a radially anisotropic permanent magnet that generates high magnetic flux density in the outer circumferential direction can be obtained.

Furthermore, if a thermoplastic nylon resin is used as the binding material, a cylindrical permanent magnet can be obtained simply by cooling after molding.

Next, after cutting into lengths of 8 mm, the epoxy resin used as the binding material is heated and solidified, and as shown in Fig. φ15 x inner diameter φ
A yoke ring 3 made of a soft magnetic material with a length of 14×8IllI11 was inscribed and fixed with adhesive, and further fixed to the shaft 5 with a plastic spacer 4 to form a rotor for use in a single-phase synchronous motor.

Since the permanent magnet is cylindrical, it can be inserted and fixed with adhesive, making it easier to assemble than pasting together the magnetic poles.

In order to magnetize 10 poles on the outer periphery of the rotor manufactured as described above, using the grooves of the rotor as positioning, insert the 10-pole magnetizing yoke so that it corresponds to the position of the magnetic poles, and use the oil capacitor bank. Magnetization was performed using a pulse magnetization power supply.

As shown in Fig. 2, a 10-pole magnetized rotor is rotated using a shaft 5, and a Hall probe is inserted into the rotor's multi-pole magnetized cylindrical permanent magnet 1 using a commercially available Gauss meter and a Hall blower 7. The curve of the surface magnetic flux density measured by contacting the outer peripheral surface is shown with the vertical axis representing the amount of change in magnetic flux and the horizontal axis representing the rotational displacement.

The curve of the surface magnetic flux density of a normal cylindrical permanent magnet without grooves is approximately sinusoidal as shown in Figure 3(a), or when the cylindrical permanent magnet has a thin wall thickness and a wide magnetic pole width. As shown in (b), the waveform has a shape close to a trapezoid with a slightly flat center, and the position of the waveform center coincides with the position of the maximum value of the surface magnetic flux density, as shown by the broken lines.

However, in the cylindrical multipolar magnetized permanent magnet of the present invention shown in Fig. 2, the position of the maximum value on the surface magnetic flux density curve (indicated by the solid line) is the waveform of the N and S poles, respectively, as shown by the broken line. Regular deviations from the center position in a specific direction.

This is because the groove portion of the cylindrical permanent magnet and the magnetic pole portion of the 10-pole magnetizing yoke are shifted at a specific angle and correspond to each other during multi-pole magnetization.

Note that the amount of deviation can be arbitrarily determined by positioning the magnetic pole position of the magnetizing yoke and the position of the arm of the rotor.

However, if the amount of deviation is increased to the maximum position of the surface magnetic flux density, the magnetic flux will decrease.

Further, if the wall thickness of the cylindrical permanent magnet is thinner than the magnetic pole width, the surface magnetic flux increases at adjacent magnetic pole portions as shown in FIG. 4, causing problems such as increased cogging torque and generation of vibration.

In the cylindrical multipolar magnetized permanent magnet of the present invention, the position of the electric wire wound around the multipolar magnetized yoke, that is, N or S
When magnetized with the pole switching position facing the rotor groove, the surface magnetic flux density at the above-mentioned portion decreases, and the magnetization distribution has the waveform shown in Figure 3 (a) or (b), resulting in a cogging torque. Decrease.

The rotor formed and multipole magnetized as described above was set in a pair of upper and lower stators called claw poles of a PM stepping motor and one excitation coil, and a rotation test was conducted.

The claw pole of a PM stepping motor has a trapezoidal or rectangular pole tooth shape, is not complicated in shape, is produced in large numbers, and is common in processing technology.

The pole teeth of the claw pole used this time had a trapezoidal shape with a slightly tapered tip, and each of the five pole teeth were interlocked alternately to form a total of 10 pairs of upper and lower stators.

Furthermore, a bipolar excitation coil is placed inside the stator, and the cylindrical multipolar magnetized permanent magnet of the present invention described above is used.
The polarized rotor was set in the stator, the bearings were fixed at both ends with end plates, and the smooth rotation of the rotor was confirmed by turning the shaft.

A single-phase synchronous motor consisting of half of the components of the assembled PM type stepping motor has a surface of a cylindrical multipolar magnetized permanent magnet when no external load is applied to the rotor or when the applied load is removed. Since the position of the maximum value of magnetic flux density is shifted in a specific direction, the center of the area of the N or S pole, which is slightly closer to the groove than the position of the maximum value, is stabilized at a point opposite to the pole teeth of the claw pole.

If the magnetic poles generated on the pole teeth of the claw pole by the current flowing through the excitation coil are different from the magnetic poles of the opposing rotor, they will be attracted to each other and no rotational movement will occur.

However, in the case of the same polarity, the rotor will repel and rotate by one magnetic pole, and will be attracted to the upper and lower opposite pole teeth next to the magnetic poles that were previously facing each other, and will stop.

The direction of rotation at this time is always in a specific direction because the position of the maximum value of the surface magnetic flux density of the cylindrical multipolar magnetized permanent magnet used in the rotor is shifted in a specific direction.

A drive circuit was connected, and a rectangular wave drive current with alternating current direction was passed through the excitation coil to observe the rotation state.

The rotor using the cylindrical multipolar magnetized permanent magnet of the present invention is
Rotates smoothly in a constant direction from low speed range, synchronizes even when the frequency of switching the drive current direction is high, and has approximately 600 Orp.
It continued to rotate in the same direction until it lost synchronization at m.

[Effects of the Invention] As described above, the cylindrical multipolar magnetized permanent magnet of the present invention has an axis for rotation in the center of the cylindrical permanent magnet, or has a soft magnetic material on the inner peripheral surface. A cylindrical multipolar magnetized permanent magnet having a cylindrical component made of or a component made of a non-magnetic material, and the outer peripheral surface of the cylindrical permanent magnet configured with a shaft is magnetized with multiple poles. By having grooves in the number corresponding to the number of magnetized poles on the outer circumferential surface described above, components that can be easily machined are used, and magnetic poles with complicated shapes as in the past are not required. This has the effect of providing a cylindrical multipolar magnetized permanent magnet that can be used to manufacture a single-phase synchronous motor with reduced assembly man-hours and a DC motor with reduced cogging torque.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cylindrical multipolar magnetized permanent magnet of the present invention. FIG. 2 is a diagram showing a surface magnetic flux density curve of a rotor using the cylindrical multipolar magnetized permanent magnet of the present invention. FIGS. 3(a) and 3(b) are diagrams showing the curves of the surface magnetic flux density of a normal cylindrical multipolar magnetized permanent magnet. FIG. 4 is a diagram showing a surface magnetic flux density curve of a cylindrical multipolar magnetized permanent magnet with a thin magnet wall. 1. Cylindrical permanent magnet 2. Groove 3. Yoke ring 4. Spacer 5. One or more shafts.

Claims (1)

[Claims] A cylindrical permanent magnet that has a shaft for rotation in its center, or has a cylindrical component made of a soft magnetic material or a component made of a non-magnetic material on its inner peripheral surface, and has a shaft. In a cylindrical multi-polar magnetized permanent magnet formed by magnetizing a cylindrical permanent magnet with multiple poles on its outer circumferential surface, the outer circumferential surface of the cylindrical permanent magnet has a number of grooves corresponding to the number of magnetized poles. A cylindrical multipolar magnetized permanent magnet.