There is provided a lubricating structure for a power transmission mechanism in which a crankshaft is coupled to a piston disposed in a cylinder bore and in which power is transmitted from the crankshaft to a camshaft. The lubricating structure includes: an idler gear that is configured to transmit power from the crankshaft to the camshaft; and an idler gear shaft that supports the idler gear via a bearing. One end portion of the idler gear shaft protrudes into the cylinder bore, and an oil passage configured to guide oil from the cylinder bore to the bearing is formed in the idler gear shaft.

Provided is an internal combustion engine having an oil circulating structure wherein oil used to lubricate valve operating members in the cylinder head drops onto an oil pan, and the oil accumulated therein is drawn up to the cylinder head again. Each on corners of the squire bottom face inside the cylinder head of the internal combustion engine, an oil dropping hole is provided to allow the oil used to lubricate valve operating members to flow thereinto. Also provided is an oil channel communicating with one or more of the oil dropping hole at the bottom thereof to guide the oil toward the driving gear transmitting the driving force of the engine.

Provided is an internal combustion engine having an oil circulating structure wherein oil used to lubricate valve operating members in the cylinder head drops onto an oil pan, and the oil accumulated therein is drawn up to the cylinder head again. Each on corners of the squire bottom face inside the cylinder head of the internal combustion engine, an oil dropping hole is provided to allow the oil used to lubricate valve operating members to flow thereinto. Also provided is an oil channel communicating with one or more of the oil dropping hole at the bottom thereof to guide the oil toward the driving gear transmitting the driving force of the engine.

There is provided a lubricating structure for a power transmission mechanism in which a crankshaft is coupled to a piston disposed in a cylinder bore and in which power is transmitted from the crankshaft to a camshaft. The lubricating structure includes: an idler gear that is configured to transmit power from the crankshaft to the camshaft; and an idler gear shaft that supports the idler gear via a bearing. One end portion of the idler gear shaft protrudes into the cylinder bore, and an oil passage configured to guide oil from the cylinder bore to the bearing is formed in the idler gear shaft.

Provided is an internal combustion engine having an oil circulating structure wherein oil used to lubricate valve operating members in the cylinder head drops onto an oil pan, and the oil accumulated therein is drawn up to the cylinder head again. Each on corners of the squire bottom face inside the cylinder head of the internal combustion engine, an oil dropping hole is provided to allow the oil used to lubricate valve operating members to flow thereinto. Also provided is an oil channel communicating with one or more of the oil dropping hole at the bottom thereof to guide the oil toward the driving gear transmitting the driving force of the engine.

Provided is an internal combustion engine having an oil circulating structure wherein oil used to lubricate valve operating members in the cylinder head drops onto an oil pan, and the oil accumulated therein is drawn up to the cylinder head again. Each on corners of the squire bottom face inside the cylinder head of the internal combustion engine, an oil dropping hole is provided to allow the oil used to lubricate valve operating members to flow thereinto. Also provided is an oil channel communicating with one or more of the oil dropping hole at the bottom thereof to guide the oil toward the driving gear transmitting the driving force of the engine.

An automotive driveline unit housing can be that of a power transfer unit (PTU), a final drive unit (FDU), or a rear drive unit (RDU). The automotive driveline unit housing has a lubricant feed passage spanning from an inlet to an outlet. The outlet can be situated near a seal of the automotive driveline unit, near a bearing of the unit, near both the seal and bearing, or near another component. The lubricant feed passage can have a flow restrictor located near its outlet. When the unit is in a connected state, lubricant is received in the lubricant feed passage via a spinning gear of the unit. The received lubricant trickles through the flow restrictor. And when the unit is in a disconnected state, lubricant continues to trickle through the flow restrictor, even though lubricant may no longer be received in the lubricant feed passage via the gear.

An automotive driveline unit housing can be that of a power transfer unit (PTU), a final drive unit (FDU), or a rear drive unit (RDU). The automotive driveline unit housing has a lubricant feed passage spanning from an inlet to an outlet. The outlet can be situated near a seal of the automotive driveline unit, near a bearing of the unit, near both the seal and bearing, or near another component. The lubricant feed passage can have a flow restrictor located near its outlet. When the unit is in a connected state, lubricant is received in the lubricant feed passage via a spinning gear of the unit. The received lubricant trickles through the flow restrictor. And when the unit is in a disconnected state, lubricant continues to trickle through the flow restrictor, even though lubricant may no longer be received in the lubricant feed passage via the gear.

An air-cooled engine capable of enhancing detection precision of a temperature sensor includes a crankcase, a crankshaft, a fan case, and an engine cooling fan. The installation direction of the crankshaft defines the front and rear direction. The fan case is provided in a front part of the crankcase, and the engine cooling fan is accommodated in the fan case. The air-cooled engine includes a cooling wind passage, a wind passage terminal end wall, an oil splashing device, and a temperature sensor. The wind passage terminal end wall is provided in a rear end of the cooling wind passage, the oil splashing device is provided on the rear side of the wind passage terminal end wall and formed to splash engine oil in the crankcase onto the wind passage terminal end wall, and the temperature sensor is attached to a front part of the wind passage terminal end wall.

An air-cooled engine capable of enhancing detection precision of a temperature sensor includes a crankcase, a crankshaft, a fan case, and an engine cooling fan. The installation direction of the crankshaft defines the front and rear direction. The fan case is provided in a front part of the crankcase, and the engine cooling fan is accommodated in the fan case. The air-cooled engine includes a cooling wind passage, a wind passage terminal end wall, an oil splashing device, and a temperature sensor. The wind passage terminal end wall is provided in a rear end of the cooling wind passage, the oil splashing device is provided on the rear side of the wind passage terminal end wall and formed to splash engine oil in the crankcase onto the wind passage terminal end wall, and the temperature sensor is attached to a front part of the wind passage terminal end wall.