Abstract: The abnormality diagnosis system 1 of a downstream side air-fuel ratio detection device 41, 42, comprises an air-fuel ratio control part 71 controlling an air-fuel ratio of an air-fuel mixture, an abnormality judgment part 72 judging abnormality of the downstream side air-fuel ratio detection device based on a characteristic of change of output of the downstream side air-fuel ratio detection device when the air-fuel ratio control part makes the air-fuel ratio of the air-fuel mixture change, and an oxygen change calculation part 73 calculating an amount of change of an oxygen storage amount of the catalyst when the air-fuel ratio control part makes the air-fuel ratio of the air-fuel mixture change. The abnormality judgment part does not judge abnormality of the downstream side air-fuel ratio detection device when the amount of change of the oxygen storage amount is less than a lower limit threshold value.

Abstract: An abnormality detection device for an air-fuel ratio detection device arranged downstream of a filter is equipped with an abnormality detection unit that detects an abnormality in the air-fuel ratio detection device based on output change characteristics of the air-fuel ratio detection device during fuel cutoff control for stopping the supply of fuel to a combustion chamber of an internal combustion engine, and a combustion determination unit that determines whether or not a combustion amount of particulate matter in a filter during fuel cutoff control is larger than a predetermined amount. The abnormality detection unit prohibits detection of an abnormality in the air-fuel ratio detection device when the combustion determination unit determines that the combustion amount is larger than the predetermined amount.

Abstract: An abnormality detection device for an air-fuel ratio detection device arranged downstream of a filter is equipped with an abnormality detection unit that detects an abnormality in the air-fuel ratio detection device based on output change characteristics of the air-fuel ratio detection device during fuel cutoff control for stopping the supply of fuel to a combustion chamber of an internal combustion engine, and a combustion determination unit that determines whether or not a combustion amount of particulate matter in a filter during fuel cutoff control is larger than a predetermined amount. The abnormality detection unit prohibits detection of an abnormality in the air-fuel ratio detection device when the combustion determination unit determines that the combustion amount is larger than the predetermined amount.

Abstract: The abnormality diagnosis system 1 of a downstream side air-fuel ratio detection device 41, 42, comprises an air-fuel ratio control part 71 controlling an air-fuel ratio of an air-fuel mixture, an abnormality judgment part 72 judging abnormality of the downstream side air-fuel ratio detection device based on a characteristic of change of output of the downstream side air-fuel ratio detection device when the air-fuel ratio control part makes the air-fuel ratio of the air-fuel mixture change, and an oxygen change calculation part 73 calculating an amount of change of an oxygen storage amount of the catalyst when the air-fuel ratio control part makes the air-fuel ratio of the air-fuel mixture change. The abnormality judgment part does not judge abnormality of the downstream side air-fuel ratio detection device when the amount of change of the oxygen storage amount is less than a lower limit threshold value.

Abstract: In order to achieve stable combustion in an internal combustion engine, the engine includes a fuel injection valve having a first nozzle hole and a second nozzle hole, and an spark plug disposed at a position through which the swirling flow flows, and which is at the downstream side of the flow of the swirling flow from an extension line of the first nozzle hole and at the upstream side of the flow of the swirling flow from an extension line of the second nozzle hole, for igniting a spray of fuel injected from the fuel injection valve, wherein the first nozzle hole and the second nozzle hole are formed in such a manner that the shortest distance from the extension line of the first nozzle hole to the spark plug becomes longer than the shortest distance from the extension line of the second nozzle hole to the spark plug.

Abstract: An internal-combustion engine includes: a direct fuel injector directly injecting fuel into a combustion chamber; and a control device. The control device performs: presumption processing that presumes, based on an operating condition of the internal-combustion engine, that a thermoplastic deposit is formed on an injection hole portion of the direct fuel injector; temperature control processing that increases a temperature of the injection hole portion when the thermoplastic deposit is presumed to be formed; and first removal processing that injects the fuel from the direct fuel injector after the temperature control processing.

Abstract: An internal-combustion engine includes: a direct fuel injector directly injecting fuel into a combustion chamber; and a control device. The control device performs: presumption processing that presumes, based on an operating condition of the internal-combustion engine, that a thermoplastic deposit is formed on an injection hole portion of the direct fuel injector; temperature control processing that increases a temperature of the injection hole portion when the thermoplastic deposit is presumed to be formed; and first removal processing that injects the fuel from the direct fuel injector after the temperature control processing.

Abstract: Stable combustion is achieved in an internal combustion engine, in cases where an air stream has occurred in a cylinder. The engine includes a fuel injection valve having a first nozzle hole and a second nozzle hole, and an spark plug disposed at a position through which the swirling flow flows, and which is at the downstream side of the flow of the swirling flow from an extension line of the first nozzle hole and at the upstream side of the flow of the swirling flow from an extension line of the second nozzle hole, for igniting a spray of fuel injected from the fuel injection valve, wherein the first nozzle hole and the second nozzle hole are formed in such a manner that the shortest distance from the extension line of the first nozzle hole to the spark plug becomes longer than the shortest distance from the extension line of the second nozzle hole to the spark plug.