JPH01128506A - Magnetizing device - Google Patents

Abstract

PURPOSE:To enable a magnetic member disposed inside the permanent magnet to be magnetized to the depths thereof, to increase the life, and to enable a magnetizing pitch to be provided up to 1mm or so with fineness and with high accuracy, by employing a specific structure in which a plurality of channels are provided on the magnet facing surface of the magnetic member, and each of the channels has a narrow entrance section and has the cross section substantially in an OMEGA-shaped configuration, so that while the width of the entrance section is smaller than the diameter of a coil member for magnetization, the size thereof is adapted to press fitting. CONSTITUTION:A magnetic yoke 20 comprises a magnet facing surface 20a which is substantially close to the internal peripheral surface of a ring-shaped permanent magnet, and on which a plurality of channels 22 are formed axially at regular intervals. Each of the channels 22 has a narrow entrance section and has the cross section in anOMEGA-shaft configuration, very nearly, so that the width of the entrance section is relatively small compared with the diameter of a coil member 24. Now, after the coil member 24 is forced to be pushed into the channel 22 through the entrance section, the channel is for the remaining space thereof filled with resin 26 or the like to fix the coil member 24 thereto. While the shape of the coil member 24 is changed a little in being forced to be pushed into the channel 20, the coil member 24 recovers the original shape in the channel 22 and is securely fixed. Therefore, even if a magnetizing current is caused to flow through the coil member 24 to apply an outward force thereto, the coil member 24 is hardly moved. Moreover, since the coil member 24 is disposed in the somewhat inner position to the magnet facing surface, the diameter thereof can be enlarged, and a large current can be caused to flow therethrough.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for magnetizing a ring-shaped permanent magnet used in a rotor for a small motor, and more specifically, to a device for magnetizing a ring-shaped permanent magnet used in a rotor for a small motor. This invention relates to a magnetizing device in which a groove for accommodating the formed magnetizing coil wire has a substantially Ω-shaped cross section, thereby making it difficult for the coil wire to move toward the magnet during celadon magnetization.

[Prior Art] For example, in a PM (permanent magnet) type stepping motor, a ring-shaped permanent magnet made of ferrite or the like is magnetized with multiple poles and used for the rotor. When magnetizing a ring-shaped permanent magnet with multiple poles (magnetization pitch of about 20 mm or less), a magnetization yoke having a groove for storing a coil wire on a surface facing the magnet is used.

An example of the prior art is shown in FIG. 5, which shows a zero magnetization yoke 10 which is a device for magnetizing the inner peripheral surface of a ring-shaped permanent magnet.
has a cylindrical shape and includes a magnet facing surface 10a that is substantially in close contact with the inner circumferential surface of a ring-shaped permanent magnet (not shown) to be magnetized,
A plurality of (eight in this case) grooves 12 are provided on the magnet facing surface 10a.
A coil wire 14 coated with insulation is housed in the groove 12 and fixed by filling with epoxy resin 16 or the like as shown in the enlarged view.

This groove 12 has a simple rectangular cross section, a semicircular shape, or a U-shaped cross section.
This is a letter-shaped groove, and the coil wire 14 is fixed at a position as close to the permanent magnet as possible.

Then, by attaching an unmagnetized permanent magnet to the outer circumferential side of the magnetizing yoke 10 and passing a predetermined current through the coil wire 14,
A magnetic field strong enough to reach saturation magnetic flux is applied to the permanent magnet to magnetize it.

[Problems to be Solved by the Invention] Particularly in such multi-pole magnetization, there is a problem that the coil wire 14 generates heat due to continuous magnetization or large current for saturated magnetization of the permanent magnet. Although a water passage is provided in the yoke 10 and cooling water is passed through it for cooling, the temperature near the coil wire 14 still rises considerably. As a result, the coil wire can be inserted into the groove 12! Epoxy resin 1 fixing 4
6 etc. are softened, and the coil wire 14 is thermally expanded.

When a magnetizing current flows through the coil wire 14, a magnetic field is generated, and force is applied to the coil wire 14. Additionally, force is applied to the coil wire 14 due to the impact of the magnetizing current. The direction of this force is toward the outside of the magnetizing yoke 10 (i.e., toward the inner circumferential side of the magnet in the case of magnetizing the inner circumferential surface of a permanent magnet), as shown by the arrow F in FIG. 14 is the direction coming out from the groove 12.

As described above, the magnetizing yoke 10 is designed to have a small clearance so as to come as close to the permanent magnet as possible, and each time a permanent magnet is attached, it comes into contact with the epoxy resin 16 and wears it out. For this reason, if magnetization is performed many times, the epoxy resin 16 will be gradually scraped off, and the insulation coating of the coil wire 14 will be damaged, causing arcing and making it unusable.

Also, since the coil wire 14 moves within the groove 12 during magnetization,
The accuracy of the magnetizing pinch also gradually decreases. In even more severe cases, the coil wire 14 and the epoxy resin 16 may be damaged by the groove 12.
In some cases, the permanent magnet protrudes significantly from the magnetizing yoke 10, making it impossible to attach the permanent magnet to the magnetizing yoke 10.

For these reasons, according to current general data, the lifespan of conventional magnetizing devices is limited to several thousand to several tens of thousands of cycles.

Furthermore, in the conventional device as described above, it is difficult to pass a large current in consideration of device life, and therefore it is difficult to magnetize the permanent magnet deep into the permanent magnet.

The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, to make it possible to magnetize deep parts of a permanent magnet by flowing a large current, to have a long life, and to make it possible to finely magnetize the pitch to about 111 with high accuracy. 'An object of the present invention is to provide a magnetizing device.

[Means for Solving the Problems] The present invention, which can achieve the above objects, comprises a magnetizing yoke in which a plurality of grooves are formed on the surface facing the magnet, and a magnetizing yoke embedded in the grooves. The groove has a substantially Ω-shaped cross section with a narrow entrance part, and the width of the artificial part is slightly narrower than the diameter of the coil wire in its natural state, but it can be press-fitted. This is a magnetizing device set to the dimensions.

As the material for embedding and fixing the magnetizing coil wire in the groove of the magnetizing yoke, epoxy resin or the like as used in the past can be used.

r effect] In the present invention, the groove formed in the magnetizing yoke has an almost Ω-shaped cross section with a narrow entrance, and the width of the entrance is slightly narrower than the diameter of the coil wire in its natural state. Therefore, when the coil wire is forcibly pushed into the groove, it is stored in the groove while being slightly deformed. The coil wire housed in the groove returns to its natural state from the deformed state during the insertion process. Then, it is firmly held by filling it with resin or the like. Accordingly, the narrow entrance portion prevents movement of the magnet under the force generated by the application of a normal magnetizing current and keeps it within the groove.

As described above, in the present invention, since the coil wire becomes difficult to move, a large current can be passed, and there is less wear on the resin, etc., and the life of the device is significantly extended.

Incidentally, the configuration of the present invention can withstand magnetization tens of thousands to hundreds of thousands of times, and has a lifespan of about 10 times longer than that of conventional devices.

In the present invention, since the coil wire is moved away from the magnet facing surface by the amount at the entrance of the groove, the efficiency may decrease slightly if the magnetizing current is small, but in reality, the coil wire can be made thicker and a large current can flow. Therefore, it is possible to magnetize deep from the magnet surface.

[Example] FIG. 1 is an explanatory diagram showing an example of a magnetizing device according to the present invention, and is an example of inner circumferential surface magnetization. The 0-magnetized yoke 20, whose overall configuration may be almost the same as that of the prior art shown in FIG. Magnet facing surface 20a
It has a structure in which a plurality of (eight in this embodiment) grooves 22 are formed in the magnet facing surface 20a at equal intervals in the axial direction, and one turn of magnetizing coil wire 2 is placed in the grooves 22.
4 is stored and fixed by filling with epoxy resin 26 or the like. As the coil wire 24, one having good arc resistance and having an insulating coating such as glass wool is used.

The main difference between the present invention and the prior art is that the magnetizing yoke 2
This is a cross-sectional shape of a groove 22 formed in the magnet facing surface 20a of No. 0. The groove 22 has a substantially Ω-shaped cross section with a narrow entrance, and the width of the entrance is slightly narrower than the diameter of the coil wire in its natural state. Of course, since the coil wire 24 is pushed through the inlet, the width of the inlet is set to such a size that the coil wire 24 can be inserted into the coil wire 24 by forcefully pushing it.

The inner part of the groove 22 in which the coil wire 24 is housed has a slightly larger and almost similar shape than the coil wire 24.

With this structure, when the coil wire material 24 is pushed in, it will be in a slightly deformed state, but after being stored in the groove 22, it will return to its original natural shape and will be fixed with the epoxy resin 26 or the like. Therefore, even if a magnetizing current is supplied and an outward force is applied, movement is blocked at the entrance, and the groove 2
In 2, there is almost no movement.

Further, since the coil wire 24 is housed in a position slightly recessed from the magnet facing surface, its wire diameter can be increased. Since the coil wire 24 can be made thicker and more difficult to move, it is possible to pass a larger current than in the conventional device.

FIG. 2 is a sectional view showing another embodiment of the present invention. This embodiment is an example in which the outer peripheral surface of a ring-shaped permanent magnet is magnetized. The inner peripheral surface of the ring-shaped magnetized yoke 30 is the magnet facing surface 30
a, on which a plurality of grooves 32 are formed, and the grooves 32
A two-turn coil wire 34 is buried therein. Here again, the groove 32 has a substantially Ω-shaped cross section with a constricted entrance.

However, in this embodiment, two coil wires 34 are arranged in the radial direction on each of the good conductors 32, and the shape of the grooves 32 is also shaped accordingly.

Although not shown in FIG. 2, the groove 32 is actually filled with epoxy resin or the like to fix the coil wire 34, as in the previous embodiment.

Even in this case, the coil wire 3 housed within 'a32
4 is subjected to a force in the direction of the outer peripheral surface of the magnet (in other words, toward the center in FIG.
held within.

Next, the magnetizing characteristics of the magnetizing device according to the present invention and the prior art are shown in FIG. 3, which shows the relationship between the magnetizing voltage on the horizontal axis and the total amount of magnetic flux on the vertical axis.

In the present invention, since the coil source wire is housed at a position slightly recessed from the magnet facing surface, the total amount of magnetic flux generated is slightly lower than in the conventional device in the region where the magnetizing voltage is low. However, if a sufficient magnetizing voltage is applied, the total amount of magnetic flux will be approximately the same as that of the conventional device, and sufficient saturation magnetization can be achieved.

In fact, it is superior to conventional devices in that it allows the coil wire to be made thicker, and because the wire does not move easily, it is possible to flow a large current, and it can magnetize deep into the permanent magnet.

Regarding the lifespan of the magnetizing device, as shown in Fig. 4, the conventional device has a magnet saturation current of soo.

When a current of about A is applied, the maximum number of magnetizations is several thousand to several tens of thousands of times, whereas in the device of the present invention, as shown in FIG. Withstands multiple times of magnetization.

[Effect of the Invention 1] As described above, the present invention has a coil wire storage groove formed on the magnet facing surface of the magnetizing yoke, which has a substantially Ω-shaped cross section with a slightly narrowed entrance, but the magnetizing pitch is A thick coil wire can be used even in a narrow space, and the wire does not move easily during magnetization, and as a result, a large current can flow.
It becomes possible to perform good magnetization of the permanent magnet even deeply.

Furthermore, as mentioned above, the movement of the coil wire is hindered by the entrance of the groove, making it difficult for it to move in the direction of the magnet. There is less wear on the fixing resin, and the service life can be significantly extended.Of course, it is also possible to almost prevent the occurrence of a situation where the permanent magnet cannot be attached to the magnetizing device due to thermal expansion of the coil wire.

Furthermore, as described above, since the coil wire is difficult to move, the magnetization pitch can be narrowed, and the precision of magnetization can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of a magnetizing yoke according to the present invention, FIG. 2 is a cross-sectional view showing another embodiment of the present invention, and FIG. 3 is a diagram showing the relationship between magnetizing voltage and total magnetic flux. FIG. 4 is an explanatory diagram showing the difference in service life between the conventional device and the device of the present invention, and FIG. 5 is a sectional view showing an example of the conventional magnetizing device. ! 0. 20. 30... Magnetizing yoke, 10a. 20a, 30a... magnet facing surface, 12, 22° 32.
...Groove, 14.24.34...Coil wire, 16.2
6...Epoxy resin. Patent applicant: Fuji Electrochemical Co., Ltd. Agent: Minoru Shigemi Figure 1 Figure 5 - Figure 2 Figure 3 Figure WE4

Claims (1)

[Claims] 1. In a magnetizing yoke having a plurality of grooves formed on a surface facing the magnet, and a magnetizing coil wire buried in the groove, the groove has a narrow cross section of approximately Ω at its entrance.
1. A magnetizing device characterized in that the width of the inlet portion is narrower than the diameter of the coil wire in its natural state, but has a size that allows press-fitting.