Abstract: The invention provides a charged filter material composed of a combination of polyester fiber and polyolefin fiber, which can exhibit high particle collection efficiency with low pressure loss, and further provides a charged filter material which is self-extinguishing in the combustibility classification according to JIS D 1201 (1977) “method of combustibility test for organic materials disposed in automobile compartment” and which does not generate dioxins at the time of incineration. Disclosed is a friction-charged filter material comprising at least 20 mass % of polyester fiber containing a phosphinic acid compound and/or sulfonic acid compound and at least 30 mass % of polyolefin fiber, as well as the above-described friction-charged filter material wherein the polyester fiber comprises a phosphinic acid compound and/or sulfonic acid compound copolymerized with a polyester molecular chain.

Abstract: It is intended to provide an electret filter which has a large surface charge density, sustains stable electret properties over a long time even in a high-temperature atmosphere and yet degrades to reduce its volume when buried for disposal; and a process for producing the same. The molar ratio of an L-lactic acid monomer to a D-lactic acid monomer ranges from 100 to 85:0 to 15 or 0 to 15:85 to 100. An electret filter having a surface charge density of 1.2×10?9 C/cm2 or more can be obtained by crystallizing by heating at a temperature from the glass transition temperature to the melting point and then, while heating to 60 to 140° C., applying a direct current corona electrical field to thereby cool to 40° C. or lower under.

Abstract: A failure detection system for an air-to-fuel ratio control system includes a exhaust gas monitor positioned upstream of a catalytic converter for monitoring an emission content of exhaust gas based on which an air-to-fuel ratio is feedback controlled so as to be maintained at a desired ratio. The system has another exhaust gas monitor positioned downstream of the catalytic converter for monitoring an emission content of exhaust gas passed through the catalytic converter. Functional failures of the exhaust gas monitor of the air-to-fuel ratio control system is judged to be present on the basis of detected emission contents only when a predetermined threshold amount of intake air is detected.

Abstract: A failure detection system for an air-to-fuel ratio control system includes a exhaust gas monitor positioned upstream of a catalytic converter for monitoring an emission content of exhaust gas based on which an air-to-fuel ratio is feedback controlled so as to be maintained at a desired ratio. The system has another exhaust gas monitor positioned downstream of the catalytic converter for monitoring an emission content of exhaust gas passed through the catalytic converter. Functional failures of the exhaust gas monitor of the air-to-fuel ratio control system is judged to be present on the basis of detected emission contents only when a predetermined threshold amount of intake air is detected.

Abstract: An engine control system for an internal combustion system changes an initially set control value either to a specified control value suitable for a grade of gasoline having a low octane rating when an engine operating condition is in a first operating zone for knocking detection ranging over a specific engine load and under a specific engine speed or to another specified value suitable for another grade of gasoline having a high octane rating when an engine operating condition is in a second operating zone for knocking detection ranging over the specific engine speed. Grades of gasoline delivered to the internal combustion engine are discriminated based on the frequency of knockings continually detected by a knock sensor. Gasoline delivered to the internal combustion engine is regarded as having a high octane rating when the frequency of knockings is at low level or as having a low octane rating when when the frequency of knockings is at a high level.