The invention relates to a power unit, in particular for a hybrid vehicle, having a two-cylinder reciprocating piston engine which comprises two pistons guided in two cylinders in a tandem arrangement and two counter-rotating crankshafts connected to the pistons by connecting rods and having an alternator that can rotate in the opposite direction to the first crankshaft and in the same direction as the second crankshaft. The invention is characterized in that the alternator is in driving engagement with at least the first crankshaft via a traction mechanism and comprises a counterbalance, wherein the first crankshaft is connected via a timing chain or a timing belt to a balancing shaft which carries a further balancing mass. The invention also relates to a vehicle, in particular a hybrid vehicle, having such a power unit.

An idle gear assembly comprises an outer ring having gear teeth formed on an external surface thereof and engaged with a crank gear and any one of the left and right balance gears. A bearing includes an inner member and an outer member in a radial direction of the bearing and a plurality of rolling bodies disposed between the inner member and the outer member. A ring has elasticity in a radial direction thereof. A hub has a flange, which is in contact with the bearing, and a penetration hole. The flange and the penetration hole are formed at one side of the hub in an axial direction. A nut is inserted through another side and mounted at a hollow portion of the ring. A bolt is inserted through the insertion hole of the bearing, the penetration hole, and the nut and fixes the bearing and the hub.

In a vehicle power unit having an internal combustion engine, a pair of power transmission gears for transmitting rotation of a crank shaft to a balancer shaft is arranged between a crankcase and a crankcase cover, and a fluid pump is provided on a power transmission gear shaft supporting a power transmission gear, by which the backlash between the crank shaft and the balancer shaft is reduced and the friction and the noise of the gears are restrained while achieving downsizing of the gears of the crank shaft and the balancer, weight reduction and downsizing of the power unit.

A balancer device includes a housing fixed to an internal combustion engine, a roller bearing disposed in the housing, a balancer shaft rotatably supported in the housing by the roller bearing, a balancer weight integrally mounted on the balancer shaft and rotatably accommodated in an weight accommodation room of the housing, an introduction part that introduces a lubricating oil from the outside to the inside of the weight accommodation room, and a discharge part that provides communication between the inside and the outside of the weight accommodation room and discharges the lubricating oil from the inside of the weight accommodation room, wherein herein the roller bearing is arranged to face the weight accommodation room.

An engine assembly having a cover for catching oil splatted by crankshaft gear and a balance shaft gear is provided. The crankshaft gear is mechanically coupled to the balance shaft gear. The balance shaft gear may be partially submerged in a pool of oil formed at the bottom of the crankcase housing. The cover includes a first cover portion having a back wall and a pair of side walls extending along a top portion and a bottom portion. The top portion covers a respective portion of a circumferential edge of the crankshaft gear. The bottom portion a respective portion of a circumferential edge of the balance shaft gear. Accordingly, oil splattered by the crankshaft gear and the balance shaft gear is caught by the cover, reducing oil entrainment and increasing oil pumping efficiency. Further, the cover helps prevent oil mist from escaping the system so as to reduce oil consumption.

A bearing cap according to one embodiment of this disclosure includes: a concave part that supports a crankshaft of an internal combustion engine; first bosses that are disposed one on each side of the concave part and each have a first bolt hole; and second bosses that are disposed one on each side of a bearing cap main body having the concave part and the first bosses so as to flank the bearing cap main body and each have a second bolt hole. The bearing cap is fixed to a first member of the internal combustion engine by first bolts inserted into the first bolt holes, and to a second member of the internal combustion engine by second bolts inserted into the second bolt holes. At least the pair of second bosses have higher rigidity than a frame.

Methods and systems are provided for an engine housing assembly. In one example, an engine housing assembly comprises an engine housing component, the housing component at least partially defining a first bore for receiving a first shaft and at least partially defining a second bore for receiving a second shaft; and a reinforcement member cast into the housing, the reinforcement member having a lower coefficient of thermal expansion than the housing component, wherein the reinforcement member at least partially surrounds the first and second bores. A method of manufacturing the engine housing assembly is also provided.

A system for providing power to a vehicle includes a combustion engine having a low number of cylinders. A mechanically driven charging mechanism is attached to the combustion engine to provide pressurized air to the combustion engine and generate increased power. The combustion engine includes a 2nd order mass balance shaft that is operatively coupled to a crankshaft of the engine. The 2nd order mass balance shaft rotates at a higher speed than the crankshaft and counters inertial forces generated by the pistons of the engine. A compressor of the mechanically driven charging mechanism is attached to the 2nd order mass balance shaft, such that the mechanically driven charging mechanism is mechanically driven by rotation of the 2nd order mass balance shaft. The high speed of the 2nd order mass balance shaft drives the compressor of the mechanically driven charging mechanism.

A balancer shaft includes a shaft body, a driven gear, a fixed member fixed to the shaft body, and an elastic member located between the driven gear and the fixed body. A projection projects from the driven gear. The fixed member includes an accommodation recess accommodating the projection. The elastic member is arranged in the accommodation recess adjacent to the projection. The projection includes an abutment side surface, which includes an outer end. The outer end and the elastic member are spaced apart in the circumferential direction by a first distance when the abutment side surface and the elastic member are in abutment without elastically deforming the elastic member. The first distance is greater than a maximum value of an elastic deformation amount of the elastic member in the circumferential direction when the elastic member is pressed between the projection and a wall of the accommodation recess.

An engine balancing system includes an engine body. At least two slider-crank mechanisms are provided inside the engine body. One of the slider-crank mechanisms is arranged opposite to the other slider-crank mechanism. A slider in one of the slider-crank mechanisms is moved at a speed and acceleration similar to a speed and acceleration of a slider in the other slider-crank mechanism. The slider-crank mechanism includes a connecting rod and a crankshaft with a crank. One end of one of the slider-crank mechanisms and one end of the other slider-crank mechanism are connected to the same crankshaft through the crank. The balancing system can effectively eliminate first-order, second-order and higher-order vibrations generated during engine operation, thus reducing the probability of equipment damage.