Abstract: A crankshaft for a V-type six-cylinder engine is equipped with first through sixth crankpins, first through fourth crank journals, and first through ninth arms for connecting the crank pins and the crank journals to each other. Of the first through ninth arms, the third arm and the seventh arm respectively have surplus weight portions (inclusive of counterweights) whose centers of gravity are situated respectively in a direction substantially opposite the first crank pin and the sixth crank pin.

Abstract: A crankshaft for a V-type six-cylinder engine is equipped with first through sixth crank pins, first through fourth crank journals, and first through ninth arms for connecting the crank pins and the crank journals to each other. Of the first through ninth arms, the fifth arm is equipped with no counterweight, and the first through third arms and the seventh through ninth arms are each equipped with a counterweight.

Abstract: A crankshaft for a V-type six-cylinder engine is equipped with first through sixth crankpins, first through fourth crank journals, and first through ninth arms for connecting the crank pins and the crank journals to each other. Of the first through ninth arms, the third arm and the seventh arm respectively have surplus weight portions (inclusive of counterweights) whose centers of gravity are situated respectively in a direction substantially opposite the first crank pin and the sixth crank pin.

Abstract: The bottom surface 18 of the cylinder head 10 is formed by an intake-side bottom surface 18a and an exhaust-side bottom surface 18b on which an intake port 13 and an exhaust port 15 are formed respectively. Further, a first wall 19 formed between an intake-side water jacket 16 and the intake-side bottom surface 18a is larger in thickness than a second wall 20 formed between an exhaust-side water jacket 17 and the exhaust-side bottom surface 18b. This structure can reduce an amount of HC included in exhaust gas.

Abstract: A valve gear for an internal combustion engine capable of promptly switching the position of a piston in a rocker arm to thereby change the engine operating condition with a satisfactory response, even in a low rotation region in which an adequate amount of oil discharged from an oil pump cannot be expected. Depending on positions of pistons slidably fitted in low-speed and high-speed cylinder portions provided in an intake driven rocker arm, a low-speed or high-speed drive rocker arm is selectively operated to press a corresponding one of the pistons. The piston in the low-speed cylinder portion switched in a low rotation region is made smaller in diameter than the piston in the high-speed cylinder portion, to be enabled to be promptly switched.

Abstract: A valve gear with a cylinder suspending mechanism of an internal combustion engine, whose entire valve gear mechanism is downsized by efficiently arranging the configuration of the valve gear including the cylinder suspending mechanism. A low-speed drive rocker arm and a high-speed drive rocker arm are disposed in front and at the rear of an intake driven rocker arm so that pistons of low-speed and high-speed cylinder portions arranged side by side in the intake driven rocker arm may be pressed by operating operation arm portions extending from the respective drive rocker arms, to thereby arrange the low-speed and high-speed cylinder portions and the low-speed and high-speed drive rocker arms around the intake driven rocker arm to gather in one place.

Abstract: A structure for a camshaft includes a cam angle detecting element arranged to face a cam angle sensor and supported in a cantilever manner by a cam journal on the outer side of the cam journal. An extension journal between the cam journal and the cam angle detecting element is enlarged toward the cam journal such that the external diameter on the side of the cam journal may be larger than the external diameter on the side of the cam angle detecting element.

Abstract: The bottom surface 18 of the cylinder head 10 is formed by an intake-side bottom surface 18a and an exhaust-side bottom surface 18b on which an intake port 13 and an exhaust port 15 are formed respectively. Further, a first wall 19 formed between an intake-side water jacket 16 and the intake-side bottom surface 18a is larger in thickness than a second wall 20 formed between an exhaust-side water jacket 17 and the exhaust-side bottom surface 18b. This structure can reduce an amount of HC included in exhaust gas.

Abstract: A valve gear with a cylinder suspending mechanism of an internal combustion engine, whose entire valve gear mechanism is downsized by efficiently arranging the configuration of the valve gear including the cylinder suspending mechanism. A low-speed drive rocker arm and a high-speed drive rocker arm are disposed in front and at the rear of an intake driven rocker arm so that pistons of low-speed and high-speed cylinder portions arranged side by side in the intake driven rocker arm may be pressed by operating operation arm portions extending from the respective drive rocker arms, to thereby arrange the low-speed and high-speed cylinder portions and the low-speed and high-speed drive rocker arms around the intake driven rocker arm to gather in one place.

Abstract: A valve gear for an internal combustion engine capable of promptly switching the position of a piston in a rocker arm to thereby change the engine operating condition with a satisfactory response, even in a low rotation region in which an adequate amount of oil discharged from an oil pump cannot be expected. Depending on positions of pistons slidably fitted in low-speed and high-speed cylinder portions provided in an intake driven rocker arm, a low-speed or high-speed drive rocker arm is selectively operated to press a corresponding one of the pistons. The piston in the low-speed cylinder portion switched in a low rotation region is made smaller in diameter than the piston in the high-speed cylinder portion, to be enabled to be promptly switched.

Abstract: A structure for a camshaft includes a cam angle detecting element arranged to face a cam angle sensor and supported in a cantilever manner by a cam journal on the outer side of the cam journal. An extension journal between the cam journal and the cam angle detecting element is enlarged toward the cam journal such that the external diameter on the side of the cam journal may be larger than the external diameter on the side of the cam angle detecting element.