The present invention relates to a power train or plant structure of a vehicle, which has an engine mounted in a vehicle body with a bore center axis of the cylinder inclining downwardly towards a cylinder head with respect to horizontal plane of the vehicle.
In a front-wheel drive vehicle or a four-wheel drive vehicle in which an engine is transversely mounted in the front portion of a vehicle body, a transmission is normally transversely mounted with respect to the vehicle body to be adjacent to the engine. A drive shaft (axle) for front wheels is mounted to extend parallel to the transmission in the back-and-forth direction or the up-and-down direction of the vehicle body, and the rotating force of the engine is transmitted to the drive shaft through the transmission.
However, in the above-mentioned prior art, the transmission is mounted to extend parallel to a crankshaft of the engine, and an angle defined between the central axis of each cylinder of the engine and a line connecting the center of rotation of the crankshaft and the center of the transmission is set to be 90.degree. or less so as to prevent interference between a cylinder block and the transmission. The crankshaft of the engine is normally located at the lowermost position of the engine. For this reason, when the engine is mounted, so that the bore center axis of each cylinder is perpendicular to the ground, the center of the transmission is located at substantially the same level as that of the bore center axis of the crankshaft or higher. More specifically, the transmission is located at a considerably low level with respect to the engine and the vehicle body. Even when the engine is slanted, the slant angle is as small as about 35.degree. to 45.degree.. For this reason, it is impossible to shift the transmission to a position considerably higher than the crankshaft. The drive shaft for the front wheels is mounted below the transmission or is mounted to extend parallel to the transmission in the back-and-forth direction of the vehicle body.
Of the above-mentioned arrangements, when the drive shaft is mounted below the transmission like in the former arrangement, the position of the drive shaft is further shifted below the transmission which is originally mounted at a low level. Therefore, the total height of a power train as a combination of the engine,, the transmission, and the drive shaft is increased, resulting in a high engine-hood line.
When the drive shaft for the front wheels is mounted to extend parallel to the transmission in the back-and-forth direction of the vehicle body as in the latter arrangement, since the crankshaft, the transmission, and the drive shaft are juxtaposed in the back-and-forth direction of the vehicle body, they are arranged to extend in the back-and-forth direction, resulting in an increase in back-and-forth length of the power train.