Engine trigger wheel

An engine having a crankshaft located within a cylinder block of the engine, the crankshaft having a number of counterweights to provide dynamic balancing of the crankshaft in use including an end counterweight located in close proximity to one end wall of the cylinder block, where an end of the crankshaft extending exterior to the end wall includes a flywheel flange, the end counterweight having a recess formed therein in which is mounted an engine trigger wheel, wherein the trigger wheel is angularly positioned and has an out-of-balance mass sufficient to compensate for an out-of-balance effect of material lost from the end counterweight due to the recess, and a cylindrical rim portion of the trigger wheel extends away from the one end wall of the cylinder block, away from the flywheel flange, in a direction parallel to an axis of rotation of the trigger wheel;

• wherein the trigger wheel is stamped from a single piece of steel comprising a central annular portion and the cylindrical rim portion which is turned over from the central annular portion, the cylindrical rim portion arranged around an outer periphery of the central annular portion and extending outward from the central annular portion in the direction parallel to the axis of rotation of the trigger wheel, the cylindrical rim portion overlying the end counterweight and spaced apart from the end counterweight, around an entire circumference of the trigger wheel, by a gap, and having a plurality of circumferentially spaced apart trigger teeth, and the central annular portion having a plurality of apertures formed therein to move a center of mass of the trigger wheel away from the axis of rotation of the trigger wheel, the plurality of apertures circumferentially spaced apart from one another around the central annular portion on a side of the central annular portion that is not aligned with a first portion of the end counterweight that extends farther outward, radially in a direction of an axis of rotation of the crankshaft, than a remaining portion of the end counterweight, and a central aperture that fits on a circumferentially extending inner wall of the recess of the end counterweight, wherein there are a number of circumferentially spaced, stamped apertures in the cylindrical rim portion and each of the trigger teeth is formed by a land between two adjacent apertures, and where the central annular portion includes a number of circumferentially spaced fixing holes used to fasten the trigger wheel to the crankshaft.

A crankshaft for an engine, comprising:

• a flywheel flange arranged at one end of the crankshaft, the flywheel flange arranged outside an end wall of a cylinder block in which the crankshaft is rotationally supported;
• an asymmetrical end counterweight arranged proximate to the flywheel flange and interior to the end wall, the end counterweight including a first portion that extends further outward in a radial direction, relative to a longitudinal axis of the crankshaft, than a second portion of the end counterweight;
• and
• a unitary engine trigger wheel, comprising:
• a central annular portion that is annular with an inner edge defined by a central aperture of the central annular portion, the central aperture centered on an axis of rotation of the trigger wheel, and an outer peripheral edge;
• and
• a cylindrical rim portion arranged around an outer periphery of the central annular portion and bent over from the central annular portion, the cylindrical rim portion having circumferentially spaced apart trigger teeth, the central annular portion including a plurality of apertures to move a center of mass of the trigger wheel away from the axis of rotation of the trigger wheel, the plurality of apertures arranged on a side of the central annular portion that is aligned with the second portion of the end counterweight and does not overlap the first portion of the end counterweight in a direction of the axis of rotation of the trigger wheel, each of the trigger teeth formed by a land between two adjacent apertures of a number of stamped apertures spaced apart in the cylindrical rim portion, where the cylindrical rim portion extends outward from the central annular portion, in the direction of the axis of rotation of the trigger wheel and where a length of each of the trigger teeth, in the direction of the axis of rotation of the trigger wheel, is longer than a thickness of the central annular portion, where a thickness of the cylindrical rim portion is equal to the thickness of the central annular portion, and where the outer peripheral edge of the central annular portion is aligned with an outer surface of the cylindrical rim portion, the outer surface of the cylindrical rim portion spaced away from, in a direction perpendicular to the axis of rotation of the trigger wheel, an outer circumferential edge of the end counterweight, via a gap that is maintained around an entirety of a circumference of each of the end counterweight and the trigger wheel, the gap arranged between the outer circumferential edge of the end counterweight and the outer surface of the cylindrical rim portion.