Abstract: An insulator composition of foamed synthetic resin is supplied to an extruder 3, and the synthetic resin is extruded onto a wire 4a continuously supplied to the extruder 3 at a temperature higher than or equal to a foaming temperature, to cover the wire 4a with the insulator composition. Then, the wire 4a covered with the insulator composition is solidified by cooling in a water-cooling trough 6 movable towards and away from the extruder 3 in a direction of supply of the wire 4a. In this operation, an outer diameter D and a capacitance C of the insulator composition are controlled such that when the water-cooling trough 6 reaches its movable limit, either a deviation .DELTA.D of a detection value of the outer diameter D from its target preset value or a deviation .DELTA.C of a detection value of the capacitance C from its target preset value is selected as a deviation (.DELTA.D or .DELTA.

Abstract: A device for detecting a change in internal pressure of a cylinder includes a cylinder head, an ignition plug threadingly fitted into a plug insertion hole of the cylinder head. An annular piezoelectric sensor is secured in the plug insertion hole by screwing the plug into the insertion hole. The sensor has such an outer periphery that, when the ignition plug is screwed into the plug hole, a part of the outer periphery of the sensor placed is brought into engagement with an inside periphery of the plug hole and is thereby prevented from being further rotated in the screwing direction. By using a gasket having the same relative shape to the periphery of the plug insertion hole as that of the above sensor, rotation of the sensor can be prevented even when the sensor does not have such a relative shape.

Abstract: A retaining ring is provided for temporarily holding a pressure sensor in place within a spark plug attaching hole prior to installation of a spark plug. The retaining ring is resiliently deformed into a stressed positioned to attach itself to a circumferential wall of the spark plug attaching hole. In one embodiment, a gasket is adapted to serve also as such a retaining ring.

Abstract: A tool is provided for loosening or tightening a spark plug while interposing a gasket and a pressure sensor between the spark plug and a cylinder head. The tool consists of concentric, relatively rotatable inner and outer cylinders. The inner cylinder is engageable with the spark plug for rotation together therewith and for loosening or tightening the same. The outer cylinder is lockingly engageable with a cylinder head by means of an axial projection of the outer cylinder and a groove of the cylinder head. The outer cylinder is further lockingly engageable with the gasket by means of a locking leg of the outer cylinder and a peripheral cut of the gasket. The gasket is thus lockingly engageable with the cylinder head by way of the outer cylinder for preventing the pressure sensor from rotating relative to the cylinder head when the spark plug is loosened or tightened.

Abstract: A data processing system having a channel processing device provided with an input/output device which requires input/output interrupt. The channel processing device responding to a request for input/output interrupt, propagating the request for input/output interrupt to a central processing unit, and reporting the state of the input/output device to the central processing unit.