Abstract: An oil passage structure of a dry sump engine includes an oil recovery passage, at least one first communicating hole, and a first oil suction passage. The oil recovery passage extends in a direction in which a cylinder bank extends and is disposed so that at least part of the oil recovery passage is located outward of an external lower end portion of a valve gear chamber of a cylinder head along a junction between a side wall portion of the cylinder head and a bottom surface of the valve gear chamber in a state where the dry sump engine is mounted on a vehicle in an inclined manner. The at least one first communicating hole is provided in the side wall portion so as to connect the valve gear chamber of the cylinder head and the oil recovery passage.

Abstract: An oil passage structure of a dry sump engine includes an oil recovery passage, at least one first communicating hole, and a first oil suction passage. The oil recovery passage extends in a direction in which a cylinder bank extends and is disposed so that at least part of the oil recovery passage is located outward of an external lower end portion of a valve gear chamber of a cylinder head along a junction between a side wall portion of the cylinder head and a bottom surface of the valve gear chamber in a state where the dry sump engine is mounted on a vehicle in an inclined manner. The at least one first communicating hole is provided in the side wall portion so as to connect the valve gear chamber of the cylinder head and the oil recovery passage.

Abstract: A balancer housing (30) consists of an upper housing (32) and a lower housing (31), and receives a pair of rotatably supported balancer shafts (11, 21) therein. An oil strainer mounting portion (37) is formed as a cylindrical wall extending downward from a bottom wall of the lower housing, and an inlet passage (67) leading to an inlet end of an oil pump (60) extends along a length of the balancer shafts adjacent to the oil strainer mounting portion. A communication passage consisting of a pair of circular holes (66) arranged along an axial line of the inlet passage is passed through a wall separating an interior of the oil strainer mounting portion with the inlet passage. The two holes provides an adequate cross sectional area without increasing the height of the balancer housing.

Abstract: In a balancer device (10) including a pair of balancer shafts (11, 21), the radial bearings (41-44) for the balancer shafts are formed solely in the balancer housing (30) and/or an integral extension (52) thereof. Because a pump cover (56) provided separately from the balancer housing does not include a radial bearing for either balancer shaft, the pump cover is not required to be attached to the balancer housing when machining the radial bearing bores in the balancer housing so that the manufacturing process is simplified, and the coaxiality of the bearing halves for each balancer shaft can be ensured without difficulty as opposed to the case where the pump cover is provided with a bearing bore which is required to be aligned with the corresponding bearing bore of the balancer housing.

Abstract: A relief device includes a relief housing constituted by a relief inflow portion, a valve passage portion, a recess, and an oil discharge portion having a relief hole; a relief valve having a small-diameter portion between a first large-diameter portion and a second large-diameter portion; and a spring elastically biasing the relief valve toward the relief inflow portion. The recess is formed at a position that is closer to the relief inflow portion side than to the oil discharge portion, the axial length of the recess is larger than the axial length of the first large-diameter portion of the relief valve, and the shortest axial distance between the recess and the relief hole is less than the axial length of the small-diameter portion.

Abstract: A balancer housing (30) consists of an upper housing (32) and a lower housing (31), and receives a pair of rotatably supported balancer shafts (11, 21) therein. An oil strainer mounting portion (37) is formed as a cylindrical wall extending downward from a bottom wall of the lower housing, and an inlet passage (67) leading to an inlet end of an oil pump (60) extends along a length of the balancer shafts adjacent to the oil strainer mounting portion. A communication passage consisting of a pair of circular holes (66) arranged along an axial line of the inlet passage is passed through a wall separating an interior of the oil strainer mounting portion with the inlet passage. The two holes provides an adequate cross sectional area without increasing the height of the balancer housing.

Abstract: A relief device includes a relief housing constituted by a relief inflow portion, a valve passage portion, a recess, and an oil discharge portion having a relief hole; a relief valve having a small-diameter portion between a first large-diameter portion and a second large-diameter portion; and a spring elastically biasing the relief valve toward the relief inflow portion. The recess is formed at a position that is closer to the relief inflow portion side than to the oil discharge portion, the axial length of the recess is larger than the axial length of the first large-diameter portion of the relief valve, and the shortest axial distance between the recess and the relief hole is less than the axial length of the small-diameter portion.

Abstract: A tensioner device 14 for an engine 1 comprises a support member 16, a blade shoe 17 coming into sliding contact with a timing chain 11 having a base end section 17a held by a cylinder block 3 and a tip end section 17b supported by the support member 16, and a leaf spring 18 held by the blade shoe 1 for pressing the blade shoe 17 against the timing chain 11 elastically. The support member 16 is formed integrally with the cylinder block 3. The tip end section 17b comes into sliding contact with a guide surface 16a formed on the support member 16 to be supported.

Abstract: The interior of a chain case 23 accommodating therein a chain-sprocket mechanism (a sprocket 12 and a silent chain 14)provided for rotating a crankshaft 11 and camshafts 5 in an interlocking fashion and a tensioner shoe 18 for applying a predetermined tension to a slack side of a chain or a guide shoe 19 for preventing the run-out of the chain on a stretched side thereof is partitioned by providing a rib 27, 28 so as to protrude from at least either of an end face of an engine E and an inner surface of a chain cover 22 joined to the end face with distal end edges of the ribs being directed toward sides 18a, 18b of the tensioner shoe or the guide shoe that are perpendicular to the crankshaft.