Electric coil arrangement

摘要

A rectangular box-shaped coil carrier(15) with wire windings(13) is held in a housing(23) with a free space above the windings filled by a cast polymer(25). The outer periphery of the coil carrier has rounded corners(27) rising above the upper level of the cast material. Curvature of the outer face of each rounded corner is such that the risk of fracture in the cast polymer and initiating from the corners of the coil carrier is avoided. The upper side of the coil core(17) inside the coil carrier(15) is also covered by cast material(25). Upper edges of the coil carrier sidewalls are immersed in the cast material and only the rounded corners(27) project above the cast material surface. Cast material fills gaps between the outer periphery of the coil carrier and the coil winding(13) and between the inner periphery of the coil carrier and coil core. Spaces between the coil wire layers are also filled. The coil is wound so that all radial winding layers have the same number of winding layers above one another in the axial direction of the coil. A connecting punched metal strip has one end for connecting to the coil wire end and a plug contact end for external connection. Plastic is injected around the entire metal strip apart from the two ends. The plastic may be used to attach the metal strip onto the inside of the coil carrier. A seal at the external connecting end prevents oil penetration. In a design variation the coil arrangement is mounted in a housing and the conductive metal strip passes through a passage between the coil unit and coil housing. A section of the metal strip is enclosed by a cast material which seals the passage against subsequent penetration by the casting material surrounding the windings. An independent claim is included for a process for injecting an insulating plastic around a conductive metal strip in which the strip is held at one or more axial positions on both sides by a spring tensioned core which each press towards the metal strip. When plastic is injected each core is pushed back against the springs by the melt pressure this allowing the area of metal strip held by the cores to be covered by casting material.