Abstract: A valve operating system for an internal combustion engine includes a valve-opening electromagnet and a valve-closing electromagnet for exhibiting an electromagnetic force for attracting an armature to operate an engine valve, and a valve-opening resilient means and a valve-closing resilient means for maintaining the armature at a predetermined neutral position during deenergization of the electromagnets. In each electromagnet, a coil is inserted between inner and outer yokes which are disposed in the form of a double-cylinder such that they open at their ends opposed to the armature and are magnetically coupled to each other at their ends opposite from the armature, and the coil is positioned so that the coil protrudes from at least one of the yokes toward the armature. The armature has an annular accommodating portion provided in a surface thereof opposed to each the electromagnets and capable of accommodating that portion of the coil which protrudes from the yoke.

Abstract: A fault diagnosis method and apparatus for a control system that includes a plurality of actuators and a plurality of sensors for controlling the operation of the actuators in accordance with the output signals of the sensors, wherein even in the case where a fault occurs in any of the actuators or any of the sensors constituting the nucleus of the system, the faulty point can be easily and inexpensively identified. In the fault diagnosis, the transmission characteristics between the individual actuators and the individual sensors are measured. On the basis of the measurements, a fault is decided on for all the transmission paths between the individual actuators and the individual sensors, thereby estimating a faulty point from the pattern of the fault decision of the transmission paths.