A reciprocating internal combustion engine includes at least one piston, which is operatively connected by two connecting rods having two crankshafts rotating in opposite directions and running parallel to each other, which crankshafts are oriented in an upright manner to a horizontal water line of a boat, and an internal combustion engine housing of the internal combustion engine is composed of at least a cylinder crank housing and a cylinder head, having inlet and outlet valves, and is bounded by an upper end face and a bottom end face. To optimize the internal combustion engine, a joint ventilation system has an oil separating device provided with an oil pre-separator and a main oil separator, via which, when operating the internal combustion engine, a mixture of oil and leaking gas, resulting in a crankcase of the cylinder crank housing, reaches, by way of a discharge line extending adjacent to the upper end face, the oil pre-separator, from where the mixture of oil and leaking gas is led into the main oil separator and there is separated into the components of oil and leaking gas. The oil flows into an oil pan connecting at the bottom end face and the leaking gas near the upper end face flows into an intake system of the internal combustion engine.

An internal combustion engine, includes a cylinder; a piston supported in the cylinder for linear displacement, wherein the piston is operatively connected with a crankshaft of the internal combustion engine via a piston rod; a linear motor including a stator and a rotor, wherein the stator has an independently operable stator element assigned to the cylinder and partially surrounding the piston in circumferential direction with respect to a longitudinal center axis of the cylinder, wherein the rotor is assigned to or forms a part of the piston, and wherein the linear motor being operable for exerting on the piston a compensation force directed in radial direction.

An internal combustion engine, includes a cylinder; a piston supported in the cylinder for linear displacement, wherein the piston is operatively connected with a crankshaft of the internal combustion engine via a piston rod; a linear motor including a stator and a rotor, wherein the stator has an independently operable stator element assigned to the cylinder and partially surrounding the piston in circumferential direction with respect to a longitudinal center axis of the cylinder, wherein the rotor is assigned to or forms a part of the piston, and wherein the linear motor being operable for exerting on the piston a compensation force directed in radial direction.

A motorcycle has a crankcase containing a crank shaft and a balancer shaft, and a cylinder and a cylinder head positioned above the crankcase, and an exhaust pipe extends from the cylinder head. The balancer shaft is positioned in front of the crank shaft, and the crankcase has a balancer shaft housing supporting the balancer shaft thereinside, and has a recessed part depressed rearward in a front end center part of the balancer shaft housing. The balancer shaft has balancer shaft weights apart from each other in one side and in the other side in an axis direction.

A moment-cancelling, four-stroke engine is disclosed. The engine includes a first cylinder having a first piston and a second cylinder having a second piston, a first crankshaft operably connected to the first piston and a second crankshaft operably connected to the second piston. The first crankshaft rotates in a first direction and the second crankshaft rotates in a second direction that is opposite the first direction to cancel the moments applied to the engine and reduce engine vibration.

Methods and systems are provided for the design and manufacture of a crankshaft of a piston internal combustion engine. In one example, a crankshaft comprises a crankshaft throw, the crankshaft throw comprising a crankpin and crank webs. The crank webs are formed asymmetrically in a region of the crankpin with respect to a plane intersecting an axis of rotation of the crankshaft and a center axis of the crankpin, such that the breaking strength of the crankshaft throw is increased at a crankshaft angle of rotation which differs from the top dead center position of a piston to which the crankpin is coupled, and at which the piston exerts a maximum combustion-induced force on the crankpin.

Methods and systems are provided for the design and manufacture of a crankshaft of a piston internal combustion engine. In one example, a crankshaft comprises a crankshaft throw, the crankshaft throw comprising a crankpin and crank webs. The crank webs are formed asymmetrically in a region of the crankpin with respect to a plane intersecting an axis of rotation of the crankshaft and a center axis of the crankpin, such that the breaking strength of the crankshaft throw is increased at a crankshaft angle of rotation which differs from the top dead center position of a piston to which the crankpin is coupled, and at which the piston exerts a maximum combustion-induced force on the crankpin.

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.

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.

The invention relates to a power unit, in particular for a hybrid vehicle, including a reciprocating-piston engine and at least one generator drivingly connected to the engine, wherein the engine has at least two pistons guided in at least two cylinders in a tandem arrangement, and two crankshafts, which are connected to the pistons by connection rods that run in opposite directions, and are mechanically coupled in the same phase. The engine includes a hub-hub connection with a first connection joining a first hub to a second hub such that an angular position between the first hub and the second hub is continuously adjustable on installation. The hub-hub connection also has a second connection in the form of a connection disk configured, dimensioned and arranged with support surfaces on each of which the first hub and the second hub rest. The connection disk has a matrix with hard material elements embedded therein, in particular diamond chips, which are arranged in the support surfaces for frictional engagement of the hubs.