Abstract: An arrangement for supporting a crankshaft in a multicylinder engien comprises a plurality of bulkheads provided in a cylinder block of the engine to be arranged at predetermined intervals along an axis of the crankshaft disposed in the cylinder block, a plurality of bearing caps each coupled with a lower end of one of the bulkheads by a cap bolt screwed into the bulkhead through a part of the bearing cap relatively close to the bulkhead so as to constitute a bearing portion for supporting the crankshaft in conjunction with the bulkhead, a beam structure extending along the axis of the crankshaft to interconnect therethrough adjacent two of the bearing caps, and a reinforcing structure coupled with the beam structure with a plurality of clamped spots generally arranged in the direction along which the crankshaft extends and also coupled with each of side skirt portions of the cylinder block with a plurality of clamped spots generally arranged in the direction along which the crankshaft extends.

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.

Abstract: An oil pan structure of generally rectangular cup-like configuration having a rear end adapted to be connected with a clutch housing, which comprises reinforcement wall structure formed with the oil pan structure so as to protrude away from the rear end towards the clutch housing. The reinforcement wall structure defines a space between the rear end of the oil pan structure and the clutch housing when the oil pan structure is secured to the clutch housing, and has a portion cut away to define an access opening communicated with the space The access opening is located immediately below at least one bolt receiving boss formed in the rear end of the oil pan structure for the passage of a fitting bolt used to connect the oil pan structure from below to a cylinder block. The oil pan structure also comprises a cover member removably fitted to the reinforcement wall structure for closing the access opening.

Abstract: In an engine cooling structure in which a water pump for causing a cooling water or coolant to flow in a watercool engine is located at or near one end portion of a cylinder block in the direction of the cylinder alignment, coolant passages include a main coolant passage disposed in a cylinder head and the cylinder block, a radiator circulating passage leading the cooling water from the water pump through an engine body to a radiator core, a by-pass passage by-passing the radiator core, and a heater circulating passage leading the cooling water from the engine body to an air-conditioning heater. The radiator circulating passage and the by-pass passage are arranged so as to switch by a thermostat valve. The by-pass passage and/or the heater circulating passage are or is constructed so as to have a coolant return passage disposed in the cylinder block extending in the direction of the cylinder alignment.

Abstract: A cylinder block construction of an engine having a pair of balancer shafts provided at its opposite sides, in which the cylinder block is formed with a pair of bearing boss portions for supporting the balancer shafts, respectively. The cylinder block construction includes a pair of mounting portions for securing a pair of engine mounts to the cylinder block, respectively, which are, respectively, provided, in the vicinity of the bearing boss portions, at opposite side walls of the cylinder block so as to be integrally formed with the bearing boss portions.

Abstract: A cylinder block is provided with a balancer case for accommodating a balance shaft. A blowby passage communicating the interior of the crankcase and the interior of the cylinder head for returning blowby to the intake system is provided to extend through a side wall of the cylinder block and the interior of the balancer case, the interior of the balancer case forming a part of the blowby passage.

Abstract: An internal combustion engine having a pair of balancing shafts carrying eccentric balancing weights and driven in a direction of counterbalancing effects of reciprocating parts. Each balancing shaft is positioned to extend in parallel with the crankshaft and supported by bearings of which upper portions are defined by deck portions formed in the cylinder block. Compact arrangements can be accomplished by the locations of the balancing shafts.

Abstract: A rotary piston engine having an exhaust port device in the rotor housing. The exhaust port device includes a single exhaust port formed in the rotor housing and an insert located in the exhaust port. The insert has a hollow body and partition walls separating the trailing part of the port opening into three sub-parts. The central one of the sub-parts is covered by a cover wall so that the port area is gradually increased to suppress exhaust noise. The insert can be rapidly brought into a high temperature during engine start so that the exhaust gas purifying system can rapidly be activated.