Abstract: A straddled vehicle engine unit including an internal combustion engine and a misfire detection device. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit and a misfire determination unit. The misfire determination unit includes first to third determination units. The first determination unit determines whether or not the crankshaft rotation speed fluctuation physical quantity acquired by the crankshaft rotation speed fluctuation physical quantity acquisition unit is greater than a set physical quantity determination reference. The second determination unit determines whether or not a fluctuation pattern constituted by a physical quantity and the crankshaft rotation speed fluctuation physical quantity acquired at least before or after the physical quantity falls within a set misfire pattern range.

Abstract: A straddled vehicle engine unit including an internal combustion engine and a misfire detection device. The internal combustion engine has a crankshaft, and a crank angle signal output unit that periodically outputs a crank angle signal in accordance with rotation of the crankshaft. The internal combustion engine is configured to repeat at least two kinds of strokes on a cycle of every 720-degree rotation of the crankshaft. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit configured to acquire a physical quantity related to an amount of fluctuation in a rotation speed of the crankshaft in one kind of stroke, out of the at least two kinds of strokes, based on the crank angle signal from the crank angle signal output unit, and a misfire determination unit configured to perform a misfire determination in response to each acquisition of the crankshaft rotation speed fluctuation physical quantity.

Abstract: A straddled vehicle engine unit including an internal combustion engine and a misfire detection device. The internal combustion engine has a crankshaft, and a crank angle signal output unit that periodically outputs a crank angle signal in accordance with rotation of the crankshaft. The internal combustion engine is configured to repeat at least two kinds of strokes on a cycle of every 720-degree rotation of the crankshaft. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit configured to acquire a physical quantity related to an amount of fluctuation in a rotation speed of the crankshaft in one kind of stroke, out of the at least two kinds of strokes, based on the crank angle signal from the crank angle signal output unit, and a misfire determination unit configured to perform a misfire determination in response to each acquisition of the crankshaft rotation speed fluctuation physical quantity.

Abstract: A straddled vehicle engine unit including an internal combustion engine and a misfire detection device. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit and a misfire determination unit. The misfire determination unit includes first to third determination units. The first determination unit determines whether or not the crankshaft rotation speed fluctuation physical quantity acquired by the crankshaft rotation speed fluctuation physical quantity acquisition unit is greater than a set physical quantity determination reference. The second determination unit determines whether or not a fluctuation pattern constituted by a physical quantity and the crankshaft rotation speed fluctuation physical quantity acquired at least before or after the physical quantity falls within a set misfire pattern range.

Abstract: An engine unit includes an internal combustion engine and a misfire detection device. The misfire detection device includes a rough road traveling determination unit that: (a) determines a rough road traveling state based on a distribution state of a crankshaft rotation speed fluctuation physical quantity acquired by a crankshaft rotation speed fluctuation physical quantity acquisition unit, or (b) includes a vehicle traveling state detection unit for detecting a physical quantity in relation to a vehicle traveling state except the crankshaft rotation speed fluctuation physical quantity, and determines a rough road traveling state based on a detection result obtained by the vehicle traveling state detection unit; and suspends a determination of a misfire in the internal combustion engine based on a determination result obtained by the rough road traveling determination unit.

Abstract: An object is to provide a misfire detection device and a vehicle with an enhanced detection reliability. A misfire detection device includes: a rotation speed acquisition unit configured to acquire a rotation speed of a rotator rotated by a four-stroke engine; a misfire determination unit configured to determine the presence or absence of a misfire in the four-stroke engine based on the rotation speed of the rotator acquired by the rotation speed acquisition unit; and a periodic fluctuation detection unit configured to detect a periodic fluctuation contained in a rotation fluctuation of the four-stroke engine based on a rotation speed acquired by the rotation speed acquisition unit, the periodic fluctuation being repeated on a circulation cycle of at least one element of a wrapping transmission element or a plurality of transmission wheels, the periodic fluctuation having a plurality of extreme values within the circulation cycle of the one element.

Abstract: An unequal-interval combustion engine misfire-determination device determines whether a misfire has occurred in an unequal-interval combustion engine including a plurality of cylinders in which combustion occurs at unequal intervals.

Abstract: A misfire determination device includes: a combustion fluctuation canceled value acquisition unit that acquires a first combustion fluctuation canceled value corresponding to a first angle position and a second combustion fluctuation canceled value corresponding to a second angle position; a combustion fluctuation manifested value calculation unit that calculates a first fluctuation manifested value by removing the first combustion fluctuation canceled value from a rotation speed at the first angle position, and calculates a second fluctuation manifested value by removing the second combustion fluctuation canceled value from a rotation speed at the second angle position; a first-order difference calculation unit that calculates a first-order difference between the first fluctuation manifested value and the second fluctuation manifested value; and a specific cylinder misfire determination unit that determines a misfire in a specific cylinder by using the first-order difference.

Abstract: The present teaching aims to provide: a cam angle sensor fault diagnosis apparatus for straddled vehicle, capable of detecting a fault of a cam angle sensor installed in a straddled vehicle and guessing a fault place; an engine system; and a straddled vehicle.

Abstract: A control device for a rotating element rotated by a four-stroke engine has a high degree of freedom in the choice of an apparatus to which the control device is applicable. The control device includes a rotation speed acquisition unit configured to obtain a rotation speed of the rotating element rotated by the four-stroke engine, and an undulation detection unit configured to, based on the rotation speed obtained by the rotation speed acquisition unit, detect a periodic undulation contained in a rotation fluctuation of the four-stroke engine, the periodic undulation having an angular period longer than a crank angle corresponding to four strokes.

Abstract: An engine unit includes an internal combustion engine and a misfire detection device. The misfire detection device includes a rough road traveling determination unit that: (a) determines a rough road traveling state based on a distribution state of a crankshaft rotation speed fluctuation physical quantity acquired by a crankshaft rotation speed fluctuation physical quantity acquisition unit, or (b) includes a vehicle traveling state detection unit for detecting a physical quantity in relation to a vehicle traveling state except the crankshaft rotation speed fluctuation physical quantity, and determines a rough road traveling state based on a detection result obtained by the vehicle traveling state detection unit; and suspends a determination of a misfire in the internal combustion engine based on a determination result obtained by the rough road traveling determination unit.

Abstract: A misfire determination device includes: a combustion fluctuation canceled value acquisition unit that acquires a first combustion fluctuation canceled value corresponding to a first angle position and a second combustion fluctuation canceled value corresponding to a second angle position; a combustion fluctuation manifested value calculation unit that calculates a first fluctuation manifested value by removing the first combustion fluctuation canceled value from a rotation speed at the first angle position, and calculates a second fluctuation manifested value by removing the second combustion fluctuation canceled value from a rotation speed at the second angle position; a first-order difference calculation unit that calculates a first-order difference between the first fluctuation manifested value and the second fluctuation manifested value; and a specific cylinder misfire determination unit that determines a misfire in a specific cylinder by using the first-order difference.

Abstract: An unequal-interval combustion engine misfire-determination device determines whether a misfire has occurred in an unequal-interval combustion engine including a plurality of cylinders in which combustion occurs at unequal intervals.

Abstract: An object is to provide a misfire detection device and a vehicle with an enhanced detection reliability. A misfire detection device includes: a rotation speed acquisition unit configured to acquire a rotation speed of a rotator rotated by a four-stroke engine; a misfire determination unit configured to determine the presence or absence of a misfire in the four-stroke engine based on the rotation speed of the rotator acquired by the rotation speed acquisition unit; and a periodic fluctuation detection unit configured to detect a periodic fluctuation contained in a rotation fluctuation of the four-stroke engine based on a rotation speed acquired by the rotation speed acquisition unit, the periodic fluctuation being repeated on a circulation cycle of at least one element of a wrapping transmission element or a plurality of transmission wheels, the periodic fluctuation having a plurality of extreme values within the circulation cycle of the one element.

Abstract: The present teaching aims to provide: a cam angle sensor fault diagnosis apparatus for straddled vehicle, capable of detecting a fault of a cam angle sensor installed in a straddled vehicle and guessing a fault place; an engine system; and a straddled vehicle.

Abstract: A control device for a rotating element rotated by a four-stroke engine has a high degree of freedom in the choice of an apparatus to which the control device is applicable. The control device includes a rotation speed acquisition unit configured to obtain a rotation speed of the rotating element rotated by the four-stroke engine, and an undulation detection unit configured to, based on the rotation speed obtained by the rotation speed acquisition unit, detect a periodic undulation contained in a rotation fluctuation of the four-stroke engine, the periodic undulation having an angular period longer than a crank angle corresponding to four strokes.

Abstract: An angular interval between a piston top dead center of one of two cylinders of an engine and a piston top dead center of the other one of the two cylinders is not a quotient of 360° CA divided by an integer number. A timing rotor is rotated synchronously with a crankshaft of the engine and includes a plurality of teeth that are arranged at equal intervals, each of which is set as a predetermined quotient of the angular interval divided by a corresponding integer number.

Abstract: An angular interval between a piston top dead center of one of two cylinders of an engine and a piston top dead center of the other one of the two cylinders is not a quotient of 360° CA divided by an integer number. A timing rotor is rotated synchronously with a crankshaft of the engine and includes a plurality of teeth that are arranged at equal intervals, each of which is set as a predetermined quotient of the angular interval divided by a corresponding integer number.