JPS6244503Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a sealing structure for preventing cracks in the excitation coil resin sealing material of an electromagnetic clutch/brake. A conventional method of sealing an excitation coil of an electromagnetic clutch/brake will be described with reference to the drawings. In Figure 1, 1 is a yoke, 2 is an excitation coil, and 3 is a resin sealing material. After installing the excitation coil 2 wound around the yoke 1, the gap between the yoke 1 and the excitation coil 2 is sealed with resin. A material 3 was sealed, and the excitation coil 2 and yoke 1 were heat-cured and fixed together. Such a sealing structure is intended to dissipate heat from the excitation coil 2 and to prevent moisture absorption in order to maintain insulation. However, in the conventional sealing structure as described above, in large excitation coils that require a large amount of resin sealing material, or in excitation coils for applications that involve rapid temperature changes, thermal expansion between the resin sealing material and the metal material Due to the difference in coefficients, there were problems in that the resin sealing material would clutch, scattering fragments, and easily absorb moisture, impairing its insulation properties. In order to solve this problem, it is necessary to eliminate the difference in the coefficient of thermal expansion between the resin sealing material and the metal material, but even with the latest resin compounding technology, the difference between the two is obvious and it is not possible to solve the problem. As long as it maintains good encapsulation workability,
The coefficient of thermal expansion of the resin sealing material is changed to that of the metal material.
Although it is possible to approximate them within a certain range, it is impossible to make the coefficients of thermal expansion of both the same. The present invention eliminates the above-mentioned basic drawbacks and provides a sealing structure with excellent crack resistance that is suitable for sealing large-sized excitation coils and excitation coils for applications involving rapid temperature changes. The purpose is to The present invention will be described below with reference to an embodiment shown in FIG. First, as in the conventional method, the excitation coil 2 wound around the yoke 1 is installed, and then the resin sealing material 3 is sealed in the gap between the yoke 1 and the excitation coil 2. Next, a fiber material 4 such as synthetic fibers with good permeability such as polyester fiber, inorganic nonwoven fabric such as glass fiber, mat, or cloth is attached to the surface of the resin sealing material 3, and the resin is contained in the fiber material. After infiltration and forming a composite layer of resin and fibers on the surface of the resin sealing material, the excitation coil 2 and yoke 1 are fixed together by heat curing. An electromagnetic clutch (rated voltage: DC36V, rated capacity:
56W, yoke outer diameter: 300mmφ) and an electromagnetic clutch with the same specifications as the conventional sealed structure, and conducted the following experiments. After the test clutch was placed in a large cryogenic chamber at -30°C, the excitation coil was overexcited from the outside. That is, as shown by A in FIG. 3, a voltage approximately five times the rated voltage was applied every two hours. As a result, the temperature of the excitation coil repeatedly changed from -30°C to +80°C, as shown by B in Figure 3. When we investigated the resin sealing material by repeating such a heat circle 500 times, we found that cracks occurred in five places in the conventional sealing structure, as shown in Table 1 below. However, the sealing structure according to the present invention did not cause any cracks.

[Table] As shown in Table 1 above, the clutch according to the present invention has significantly improved crack resistance compared to clutches with conventional structures, and despite the severe test conditions, the clutch of the present invention has significantly improved crack resistance. There was no occurrence of this, and it was confirmed that the quality was stable. As mentioned above, the excitation coil sealing structure of the electromagnetic clutch/brake according to the present invention can be used for large excitation coils or excitation coils for applications involving rapid temperature changes, which cannot be achieved with conventional sealing structures. Since it is possible to completely prevent the occurrence of cracks in the unused resin sealing material, there is an extremely excellent effect in that it is possible to manufacture excitation coils for electromagnetic clutches and brakes of extremely stable quality.

[Brief explanation of the drawing]

Fig. 1 is a left half sectional view showing the excitation coil sealing structure of a conventional electromagnetic clutch/brake, Fig. 2 is a left half sectional view showing an embodiment of the present invention, and Fig. 3 is a sectional view of the left half showing the excitation coil sealing structure of a conventional electromagnetic clutch/brake. It is a graph which shows a cycle and a temperature cycle of an excitation coil. 1: Yoke, 2: Excitation coil, 3: Resin sealing material, 4: Fiber material.

Claims (1)

[Scope of utility model registration request] A fiber material 4 such as a synthetic or inorganic nonwoven fabric, mat, or cloth with good permeability is attached to the surface of the resin sealing material 3 sealed in the gap between the yoke 1 and the excitation coil 2. An excitation coil sealing structure for electromagnetic clutches and brakes whose surface is coated with a composite layer of resin and fiber.