Abstract: A misfire detection device for an engine, includes: a misfire detection part for detecting a misfire state in at least one cylinder of the engine; an effective misfire determination part for determining, on the basis of an unburned parameter that is an indicator of an unburned fuel concentration in an exhaust gas duct, a risk of unburned fuel in the exhaust gas duct burning, when the misfire detection part detects the misfire state; and an engine stop processing control part for performing stop processing of the engine on the basis of a determination result in the effective misfire determination part.

Abstract: A fuel injection valve has a first groove cut in a peripheral surface of a needle valve and second grooves cut in a seat surface of a nozzle tip. The first groove is provided so that the needle valve is rotated by flow of the fuel in the first groove caused by a reciprocating motion of the needle valve, and upper and lower ends of the first groove are opened to the outside so that the fuel can be introduced into the groove. The second grooves are twisted or tilted in the same direction as the rotating direction of the needle valve and are cut along the circumferential direction of the nozzle tip. The second grooves have an edge part for scraping off solid matters into the second grooves in cooperation with the tip seat surface of the needle valve by the rotation of the needle valve.

Abstract: A fuel injection valve in which, even in an engine in which a fuel containing many foreign matters is used, pinching of solid foreign matters, such as impurities, dirt and dust, and combustion residues, in a sliding part on the outer periphery of a needle valve, the tip of the needle valve, and a seat of a nozzle tip, malfunction an seizure of the needle valve due to such containing, and poor combustion due to irregular injection are prevented from occurring. The fuel injection valve has a first groove cut in the periphery surface of the needle valve and the second grooves cut in a seat surface of the nozzle tip. The first groove is provided so that the needle valve is rotated by flow of the fuel in the first groove caused by reciprocating motion of the needle valve, and the upper and lower ends of the first groove are opened to the outside so that a part of fuel can be introduced in to the groove.

Abstract: A fuel injection valve in which, even in an engine in which a fuel containing many foreign matters is used, pinching of solid foreign matters, such as impurities, dirt and dust, and combustion residues, in a sliding part on the outer periphery of a needle valve, the tip of the needle valve, and a seat of a nozzle tip, malfunction an seizure of the needle valve due to such containing, and poor combustion due to irregular injection are prevented from occurring. The fuel injection valve has a first groove cut in the periphery surface of the needle valve and the second grooves cut in a seat surface of the nozzle tip. The first groove is provided so that the needle valve is rotated by flow of the fuel in the first groove caused by reciprocating motion of the needle valve, and the upper and lower ends of the first groove are opened to the outside so that a part of fuel can be introduced in to the groove.