Patent ID: 8757123

Claim:
An internal combustion engine, comprising: a first cylinder having a central axis; a second cylinder having a central axis parallel to the central axis of the first cylinder; a unitary crankshaft situated between the two cylinders and having at least five journals and four webs: a front main journal having a central axis collinear with an axis of rotation of the crankshaft; a rear main journal having a central axis collinear with the axis of rotation of the crankshaft; a central eccentric journal; a front eccentric journal between the front main journal and the central eccentric journal; a rear eccentric journal between the rear main journal and the central eccentric journal; a front outer web located between the front main journal and the front eccentric journal; a front inner web located between the front eccentric journal and the central eccentric journal; a rear inner web located between the central eccentric journal and the rear eccentric journal; a rear outer web located between the rear eccentric journal and the rear main journal; wherein: a central axis of the front and rear eccentric journals is offset from the axis of rotation by an outer crank throw; a central axis of the central journal is offset from the axis of rotation by an inner crank throw; the front and rear eccentric journals are substantially equally phased; and the central eccentric journal is asymmetrically phased with respect to the front and rear eccentric journals; the engine further comprising: a first piston disposed in the first cylinder and coupled to the central eccentric journal via a first pushrod; a second piston disposed in the second cylinder and coupled to the central eccentric journal via a second pushrod; a third piston disposed in the first cylinder and coupled to the front eccentric journal via a first pullrod and coupled to the rear eccentric journal via a second pullrod; and a fourth piston disposed in the second cylinder and coupled to the front eccentric journal via a third pullrod and coupled to the rear eccentric journal via a fourth pullrod, wherein: reciprocation of the pistons, the pushrods, and the pullrods generates an unbalanced inertia force; the front inner web includes a first counterweight; the rear inner web includes a second counterweight; the first and second counterweights cause the center of gravity to be displaced from the axis of rotation of the crankshaft to at least partially counteract the unbalanced inertia force; a crankshaft pulley coupled to the crankshaft; an accessory pulley counter rotating at the same speed as the crankshaft pulley with the crankshaft pulley and the accessory pulley engaged via a flexible member; an accessory shaft and an accessory coupled to and rotating with the accessory pulley; and a counterweight coupled to the accessory shaft.