JPS5868911A - Cooling method for electromagnet - Google Patents

Abstract

PURPOSE:To raise the cooling efficiency of a coil and reduce the same in volume, by filling the space between the turns of an excitation coil with a magnetic fluid obtained by dispersing ferromagnetic particles into a solvent so as to be colloidal. CONSTITUTION:Ferromagnetic particles, such as magnetite, manganese ferrite, nickel ferrite, cobalt ferrite, manganese-zinc ferrite, nickel-zinc ferrite, barium ferrite and so forth, having a particle diameter of 100-200Angstrom are coated with a long-chain unsaturated fatty acid surface-active agent, such as oleic acid and linolic acid. The coated ferromagnetic particles are dispersed into a solvent, such as a fatty hydrocarbon, aromatic hydrocarbon and water, by employing an anionic or nonionic surface-active agent, thereby to prepare a colloidal solution. The solution is filled in the space 8 in a coil 7 wound on a bobbin 6. This permits the heat generated inside the coil to be easily conducted to the surface thereof, so that it becomes unnecessary to provide any cooling plate.

Description

[Detailed description of the invention] The present invention relates to a method for cooling an electromagnet.

The conventional method for cooling an electromagnet is to insert a steel heat sink 4 at an appropriate interval between the coils 30 wound around the bobbin 2 on the pole piece 1, as shown in FIG. , or a method is adopted in which this heat sink is water-cooled. However, these cooling methods have the disadvantage that the volume inside the bobbin is bulky and water cooling piping is required.

The present invention has been devised to eliminate this drawback. Therefore, in the electromagnet cooling method of the present invention, in an electromagnet formed by winding an excitation coil around an iron core, This is characterized in that the space is filled with a magnetic fluid in which ferromagnetic particles are dispersed in a solvent to form a cotetraid body, thereby improving the cooling efficiency of the excitation coil.

Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings.

An example is shown in FIG. To explain with reference to the figure, numeral 5 is a pole piece of an electromagnet, 6 is a bobbin of an excitation coil, and 7 is a winding of an excitation coil. The key point of the present invention is that the space between the windings 7 of the coil is filled with magnetic fluid 8. In this magnetic fluid, ferromagnetic particles such as 100 to 200 μm of i-gnetite, i-ganfetzite, nickel ferrite, cobalt ferrite, i-magnetic lead ferrite, nickel-zinc ferrite, barium fetuite, etc. are added to the magnetic fluid. The long-chain structure is coated with a saturated fatty acid surfactant, and then dispersed in a solvent such as aliphatic hydrocarbon, aromatic hydrocarbon, or water using an anionic or nonionic surfactant. Lloyd's solution is used. Unlike ordinary suspensions, such cotetraid solutions have excellent dispersibility and do not cause solid-liquid separation such as sedimentation or aggregation due to K such as gravity or magnetic fields.

In this embodiment configured as described above, the thermal conductivity of the magnetic fluid 8 is about 1Q-'W/as・d, and it is 1Q-'W/as・d.
0 W/Q11-1! Since it is one order of magnitude larger than
The heat generated inside the coil can be easily conducted to the surface, thereby improving heat dissipation. Therefore, there is no need to insert a conventional cooling plate between the coils, and the volume of the coil portion can be reduced by several to ten-odd percent.

Note that the magnetic fluid filled in the coil is held by the adhesion force due to capillary action to the winding and the residual magnetism of the pole piece O.

Next, as an actual example, FIG. 4 shows the cooling performance of the electromagnet shown in FIG. TS3 when it is filled with magnetic fluid and when it is not filled with magnetic fluid. Note that each coil in Figure li3 had 1000 turns, and the excitation current was 10A.

C. Curve B shows the temperature rise when filled with magnetic fluid, and curve B shows the 1 degree rise when no magnetic fluid is filled.
K showed me. As shown in Figure 1, when the magnetic fluid is filled, the temperature is about 15C lower than when it is not filled, and the effect can be seen. Figure 5 shows the results of measuring the difference in magnetic field when the electromagnet shown in Figure 3 is filled with magnetic fluid and when it is not filled. , song 118 shows the case where the magnetic fluid is not filled. As shown in the figure, filling the Kai fluid has almost no effect on the magnitude of the magnetic field generated in relation to the pole piece. However, there is a tendency for the uniformity of the magnetic field to increase slightly near the center, but this is preferable because the area where a uniform magnetic field can be formed can be increased.

As explained above, the method for cooling an electromagnet of the present invention is to efficiently cool the coil by filling the space between the windings of the coil with magnetic fluid. It can also be reduced to a 6-round shape.

[Brief explanation of drawings]

@ Figure 1 is an explanatory diagram explaining the conventional cooling method for electromagnets, Figure 2 is a cross-sectional diagram of an electromagnet using the cooling method according to the present invention, Figure 6 is an explanatory diagram of the electromagnet used for characteristic comparison, and Figure 4 Figure 5 and Figure 5 compare the characteristics of the electromagnet shown in dX3 diagram with and without filling with magnetic fluid. Figure 4 is a cooling characteristic diagram, I! Diagram I5 is a magnetic field characteristic diagram. 5... Pole piece, 6... Bobbin, 7... Coil winding, 8... Magnetic fluid. Fujitsu Limited Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney 1) Male Patent Attorney Akiyuki Yamaguchi Figure 1 Figure 2

Claims (1)

[Claims] t In an electromagnet formed by winding an excitation coil around an iron core, the space between the excitation coil O windings is filled with a magnetic fluid in which ferromagnetic particles are dispersed in a solvent to form a ':Iw oid shape, and the excitation # 4; An electromagnet cooling method characterized by improving the cooling efficiency of the electromagnet.