1. Technical Field
The disclosure relates to a system and method for heating engine oil of an internal combustion engine.
2. Background
Within the context of the present disclosure, the expression “internal combustion engine” encompasses diesel engines, spark-ignition engines and engines of any other suitable combustion mode.
Internal combustion engines typically have a cylinder block with a plurality of cylinders coupled to a cylinder head to form combustion chambers.
A piston is provided in each cylinder of an internal combustion engine guided in an axially movable manner within the cylinder or a cylinder liner. The cylinder liner, cylinder head and piston crown delimit the combustion chamber associated with one cylinder. The piston crown forms a part of the combustion chamber and, together with the piston rings, seals off the combustion chamber with respect to the crankcase to limit combustion gases from entering the crankcase and to limit oil passing into the combustion chamber.
The piston serves to transmit the gas forces generated by the combustion to the crankshaft. The piston is articulatedly connected by a piston pin to a connecting rod, which in turn is movably mounted on the crankshaft.
The crankshaft, which is mounted in the crankcase, absorbs the connecting rod forces, which are composed of the gas forces as a result of the fuel combustion in the combustion chamber and the mass forces as a result of the non-uniform movement of the engine parts. The reciprocating movement of the pistons is transformed into a rotating rotational movement of the crankshaft. The crankshaft transmits the torque to the drivetrain. A part of the energy transmitted to the crankshaft is used for driving auxiliary units such as the oil pump and the alternator, and/or serves for driving the camshaft and therefore for actuating the valve drive.
Generally, and within the context of the present disclosure, the upper portion of the crankcase is formed by the cylinder block. The crankcase is complemented by a lower crankcase portion which can be mounted on the upper crankcase portion and which serves as an oil pan. To hold the lower crankcase portion, the upper crankcase portion has a flange surface. In general, to seal off the oil pan or the crankcase with respect to the environment, a seal is provided in or on the flange surface. The connection between the crankcase portions is often provided by bolts.
To hold and mount the crankshaft, bearing saddles are formed in the upper crankshaft portion and one piece of a two-piece sleeve bearing is mounted in the bearing saddle. Typically, a bearing cap is coupled to the crankcase and the other part of the two-piece sleeve bearing is mounted in the bearing cap. The crankshaft is mounted in the region of the crankshaft journals which are arranged spaced apart from one another along the crankshaft axis and are generally formed as thickened shaft shoulders. In an alternative embodiment, the crankshaft rides directly upon the parent metal of the cylinder block and the bearing cap, i.e., without a separate sleeve bearing. The bearing surfaces in the bearing saddle and the bearing cap upon which the journal of the crankshaft rides is supplied engine oil to provide a load-bearing lubricating film.
To supply the bearings with oil, a pump for feeding engine oil to the at least two bearings is provided, with the pump supplying engine oil via a supply duct to a main oil gallery, from which ducts lead to the at least two bearings. In some engines, the supply duct leads from the pump through the cylinder block to the main oil gallery. To form the main oil gallery, a main supply duct is often provided which is aligned generally along the longitudinal axis of the crankshaft. The main supply duct may be arranged above or below the crankshaft in the crankcase or else may be integrated into the crankshaft.
An oil pump provides a sufficiently large feed flow at a sufficiently high oil pressure in the supply system, in particular to the main oil gallery. In some engines, a permanent oil supply to the at least two bearings is not supplied. In particular if the oil supply of the bearings is connected or interacts with a further oil supply for example via the main oil gallery, a permanent oil supply to the bearings is not supplied. Instead, a merely regular, but not continuous, oil supply to the bearings is supplied to limit pressure drop in the system.
Oil is supplied also to bearings associated with a camshaft. The camshaft may be cradled in a plurality of bearing saddles provided in the cylinder head and a plurality of bearing caps that couple to the cylinder head to hold the camshaft in place. The camshaft may ride on the parent material of the cylinder head and the bearing cap or upon a two-piece sleeve bearing provided in the bearing saddle and bearing cap.
An oil supply to bearings associated with the camshaft is supplied. The camshaft is also conventionally supplied with lubricating oil, for which purpose a supply duct is provided. In some systems, a duct branches off from the main oil gallery extending through the cylinder block and, in the case of overhead camshafts, and extending into the cylinder head.
Fuel consumption of the internal combustion engine is affected by the friction in the crankshaft and camshaft bearings. The friction depends on the viscosity, and therefore the temperature of the engine oil.
On account of the limited petroleum reserves, it is desirable to minimize fuel consumption in internal combustion engines. A lesser fuel consumption contributes also to lower emission of regulated pollutants as wells as carbon dioxide. It is desirable to raise the temperature of the lubricating oil quickly after a cold start of the engine to reduce friction.