A powertrain includes a housing and a crankshaft-balancing assembly that is at least partially disposed inside the housing. The crankshaft-balancing assembly includes a crankshaft rotatable about a longitudinal axis. The crankshaft-balancing assembly further includes a drive member secured to the crankshaft. The crankshaft-balancing assembly also includes a first shaft rotatable about a first pivot axis. The first shaft is rotatable in response to rotation of the crankshaft. The crankshaft-balancing assembly includes a weight member that extends from the first shaft. The weight member is positioned along the first shaft to balance the crankshaft during rotation of the crankshaft and the first shaft. The crankshaft-balancing assembly also includes a drive member that surrounds the first shaft and a portion of the weight member. The drive member of the first shaft defines a void that opposes the portion of the weight member.

An internal combustion engine that includes an oil baffle in the oil sump. The internal combustion engine may include a crankcase comprising an oil sump containing an oil reservoir, a crankshaft, and an oil baffle positioned within the oil sump. The crankshaft may be a vertical crankshaft and a first balance shaft may extend upward from the oil baffle. The crankshaft may be positioned within the oil baffle and a drivetrain may, also optionally, be positioned in the oil baffle. The internal combustion engine may be configured such that the oil reservoir has a first oil level when the internal combustion engine is off and a second oil level when the internal combustion engine is running at normal operating conditions. The first oil level is above a floor of the oil baffle. The second oil level may, also, be above the floor of the oil baffle.

A machine having a reciprocating slider crank mechanism, wherein an axis of a crankshaft, an axis of a first balancer shaft and an axis of a second balancer shaft are not arranged on the same plane, wherein vibration is highly controlled. The machine includes the reciprocating slider crank mechanism configured so as to satisfy setting formulae below:

U.sub.Cr=U.sub.P0.5

.sub.Cr=180

U.sub.B(Fr)={U1B(Fr).sup.++U2B(Fr).sup.2}.sup.1/2

U1.sub.B(Fr)=U.sub.P0. 5{Lx.sub.B(Rr)/(Lx.sub.B(Rr)Lx.sub.B(Fr))}

U2.sub.B(Fr)=U.sub.P0.5{Ly.sub.B/(Lx.sub.B(Rr)Lx.sub.B(Fr))}

.sub.B(Fr)=180arctan(U2.sub.B(Fr)/U1.sub.B(Fr))

U.sub.B(Rr)={U1.sub.B(Rr).sup.2+U2.sub.B(Rr).sup.2}.sup.1/2

U1.sub.B(Rr)=U.sub.P0.5{Lx.sub.B(Fr)/(Lx.sub.B(Fr)Lx.sub.B(Rr))}

U2.sub.B(Rr)=U2.sub.B(Fr)

.sub.B(Rr)=180arctan(U2.sub.B(Rr)/U1.sub.B(Rr)).

An offset in-line four cylinder engine has reduced vibration generated by a secondary inertia couple based on lateral pressures from pistons. A reference line passes through a shaft center of a crankshaft and is parallel or substantially parallel to cylinder axes of four cylinders as viewed in the axial direction of the crankshaft. As viewed in the axial direction of the crankshaft, the direction in which the reference line extends is referred to as first direction, and the direction perpendicular to the first direction is referred to as second direction. A distance between the shaft center of a first balancer shaft and the reference line as measured in the second direction is different from the distance between the shaft center of a second balancer shaft and the reference line as measured in the second direction, or a magnitude of a first unbalancing portion is different from a magnitude of the second unbalancing portion.

A four-stroke internal combustion engine including variable compression ratio comprises a crankcase including a crankshaft having a crankpin and being supported by the crankcase and rotatable with respect thereto about a crankshaft axis, a connecting rod including a big end and a small end, a crank member being rotatably mounted on the crankpin, and comprising at least a bearing portion which is eccentrically disposed with respect to the crankpin, a crank member drive system for rotating the crank member at a rotation frequency with respect to the crankcase which is half of that of the crankshaft, and a control system for operating the engine with repetitive cycles, wherein the compression ratio in the compression stroke is changed. The control system is configured to interrupt the repetitive cycles by rotating the crankshaft an additional single revolution between two successive combustion strokes for switching between a high and low compression ratio.

Variable counterweight apparatuses, systems and methods. The variable counterweight system includes at least one rotatable actuator, a first variable counterweight assembly, and a second variable counterweight assembly. The first variable counterweight assembly is rotatably coupled to the rotatable actuator to rotate about a first axis. The first variable counterweight assembly is configured to geometrically reconfigure so as to change a first variable counterweight assembly center of gravity position with respect to the first variable counterweight assembly. The second variable counterweight assembly is rotatably coupled to the rotatable actuator to rotate about a second axis. The second variable counterweight assembly is configured to geometrically reconfigure so as to change a second variable counterweight assembly center of gravity position with respect to the second variable counterweight assembly.

An internal combustion engine that includes an oil baffle in the oil sump. The internal combustion engine may include a crankcase comprising an oil sump containing an oil reservoir, a crankshaft, and an oil baffle positioned within the oil sump. The crankshaft may be a vertical crankshaft and a first balance shaft may extend upward from the oil baffle. The crankshaft may be positioned within the oil baffle and a drivetrain may, also optionally, be positioned in the oil baffle. The internal combustion engine may be configured such that the oil reservoir has a first oil level when the internal combustion engine is off and a second oil level when the internal combustion engine is running at normal operating conditions. The first oil level is above a floor of the oil baffle. The second oil level may, also, be above the floor of the oil baffle.

There is provided a balancer device of an engine, configured to reduce rotation vibrations of the engine. A crankshaft is provided with a primary drive gear. A countershaft is provided with a primary driven gear meshed with the primary drive gear. A plurality of balancer shafts are provided with balancer driven gears meshed with the primary drive gear.

Provided is a balancer device for an internal combustion engine capable of effectively decreasing gear rattle between gears of a drive mechanism. A balancer drive gear and a balancer driven gear are arranged on a second end side of a drive-side balancer shaft and a second end side of a driven-side balancer shaft, respectively, and an oil pump is arranged on a first end side of the driven-side balancer shaft via the drive mechanism.

An engine includes a crankshaft rotatable about a crank axis, and at least one balance shaft rotatable about a respective balance axis. The balance shaft rotates about the balance axis to balance the engine during rotation of the crankshaft about the crank axis. A torque transmitting mechanism is selectively moveable between an engaged position and a disengaged position. When the torque transmitting mechanism is disposed in the engaged position, the torque transmitting mechanism connects the crankshaft and the balance shaft in torque communication for rotating the balance shaft with the crankshaft to balance the engine, and when disposed in the disengaged position, the torque transmitting mechanism disconnects torque communication between the crankshaft and the balance shaft for not rotating the balance shaft with the crankshaft as the crankshaft rotates about the crank axis, to reduce spin losses of the engine.