Internal combustion engine

An internal combustion engine comprising:

• a crankcase that defines a crank chamber;
• a crankshaft that is rotatably supported on the crankcase via a pair of bearings and has a crank housed in the crank chamber;
• a to-be-detected body that is housed in the crank chamber and is supported on the crankshaft;
• and
• a detection sensor that is made to face a trajectory of the to-be-detected body and detects movement of the to-be-detected body to generate a pulse signal,
• wherein the to-be-detected body is disposed on an inner side of the bearing, and
• wherein the crank comprises:
• a first crank web that has a crank weight and a first shaft supported on one of the bearings so that they can rotate around the rotational axis and that supports the to-be-detected body;
• a second crank web that has a crank weight and a second shaft supported on the other of the bearings so that they can rotate around the rotational axis and that supports a centrifugal oil filter;
• and
• a crank pin that is disposed at a position displaced from the rotational axis of the crankshaft, links the first crank web and the second crank web to each other, and is linked to a connecting rod.