Denso Corporation

Tomohiro Teramachi

Shinji Usami

Tadahiro Kurasawa

A magnet switch which may be employed in automotive engine starters is provided. The magnet switch includes a stationary magnetic core made up of a disc assembly and a core body. The disc assembly is made of a stack of annular plate members superposed on each other. Each of the plate members has an opening through which a terminal lead of a magnetic coil extends. The core body has a boss with an edge which is plastically deformed outwardly in the radius direction thereof or staked to create an elastic nip which retains the stack of the plate members firmly on the core body. This structure ensures the joint between the disc assembly and the core body to withstand mechanical impact exerted on the magnetic core and stability in operation of the magnet switch without increasing a total production cost of the magnetic switch.

Magnet switch with magnetic core designed to ensure stability in operation thereof

In an electromagnet switch, a stationary iron core is composed mainly of a base part and a disk part. The base part is faced to a plunger and the disk part is forcedly inserted and fixed to a boss part formed in the base part. The disk part is composed of a metal plate of ferromagnetic substance (iron plate) and another substance plate (made of resin or rubber and the like, for example,) of a smaller spring constant or a larger damping coefficient than that of the metal plate. The metal plate and another substance plate are laminated. Another substance plate absorbs or reduces the impact force when the plunger is electromagnetically attracted toward and collides with the base part. The propagation of a large impact noise or crashing sound is thereby suppressed, and as a result the impact noise can be reduced.

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Kariya, Japan

Tomohiro Teramachi