JPS6457702A - Coil device - Google Patents

Abstract

PURPOSE:To prevent the dispersion of inductance values at every product by inserting a cylindrical elastic body, into which magnetic powder is mixed, into an air core section in a coil and respectively bringing both ends of the elastic body into pressure-contact with the inwall surfaces of ferrite cores. CONSTITUTION:A cylindrical elastic body 8 into which magnetic powder is mixed is inserted into an air core section 1b in a bobbin 1, and the size of the elastic body 8 is designed at a value slightly longer than the height of a housing space formed by ferrite cores 6 and 7. The bobbin 1, a coil 2 and the elastic body 8 are housed between the ferrite cores 6 and 7, and the ferrite cores 6 and 7 are fixed mutually with adhesives, etc. Since the elastic body 8 is designed at the slightly longer value, both ends of the elastic body 8 are in pressure-contact respectively with the inwall surfaces of the ferrite cores 6, 7, and the displacement of the size of a wall section 7b in the ferrite core 7 is absorbed by the elastic force of the elastic body 8 even when the size of the wall section 7b is to some extent displaced, thus generating no gap in all sections between the ferrite cores 6 and 7, between the ferrite core 6 and the elastic body 8 and between the ferrite core 7 and the elastic body 8.