Abstract: A first balancer shaft includes a shaft extension portion extending forward, to which a driven sprocket is attached. A case member includes a first bearing portion supporting the balancer shaft near its weight portions and rotational gear and a second bearing portion supporting the same near its driven sprocket. The case member includes an upper case coupled to a cylinder block and a lower case facing to the upper case, and there is provided a case extension portion extending forward at the upper case. The first bearing portion is configured of a hole formed by half-split portions of the both cases and the second bearing portion is configured of a hole formed integrally at the case extension portion.

Abstract: A first balancer shaft includes a shaft extension portion extending forward, to which a driven sprocket is attached. A case member includes a first bearing portion supporting the balancer shaft near its weight portions and rotational gear and a second bearing portion supporting the same near its driven sprocket. The case member includes an upper case coupled to a cylinder block and a lower case facing to the upper case, and there is provided a case extension portion extending forward at the upper case. The first bearing portion is configured of a hole formed by half-split portions of the both cases and the second bearing portion is configured of a hole formed integrally at the case extension portion.

Abstract: A balancer case (21) is coupled to the lower portion of a cylinder block (10) through turrets (12) made of a material having almost the same coefficient of linear expansion as that of a crankshaft (11) and balancer shaft (22).

Abstract: An internal combustion engine having a reinforced cylinder block, a skirt portion integrally formed therewith at a lower portion thereof, a plurality of bearings received therein, a crank shaft journaled in the bearings, a plurality of bearing caps secured to the bearings, and front and rear covers formed at front and rear portions of the cylinder block, respectively, and having respective openings through which the crank shaft extends. In order to reinforce the cylinder block, a reinforcing member is secured to a lower surface of the skirt portion of the cylinder block and to a lower surface of the rear cover. At least two first bolts for fastening the reinforcing member to the lower surface of the rear cover are provided on opposite sides of the rear cover while at least two second bolts for fastening the reinforcing member to a bearing cap for a rearmost bearing of the bearings are placed within a pitch of the first bolts in a direction transversely of the cylinder block.

Abstract: A balancer shaft for use in a multicylinder engine comprises a balance weight part formed to be eccentric in relation to a rotation axis of the balancer shaft and disposed along the alignment of cylinders in a cylinder block, an elongated shaft part extending from the balance weight part along the alignment of cylinders, a driving device provided on an end portion of the elongated shaft part for transmitting the rotation of a crank shaft in the cylinder block to the balancer shaft, a first journal provided on the end portion of said elongated shaft part, a second journal provided on a central portion of the balance weight part, and a third journal provided on an end portion of the balance weight part. The first, second and third journals are supported respectively by first, second and third bearing portions provided in the cylinder block.