After passing the oil filter, some of the oil is supplied to the main bearings of the crankshaft through various channels in the cylinder block and through holes. Through the holes in the crankshaft, the oil is supplied to the connecting rod bearings of the crankshaft. Lubrication of the cylinder walls and the lower part of the piston crown is carried out mainly by splashing. A special hole is provided in the piston head of the connecting rod and in the piston pin bushing for lubricating the piston pin.
Some of the oil, after passing through the oil filter through the holes in the cylinder block, is directed to the cylinder head for lubrication:
- driven gear of the intake camshaft;
- camshaft bearing journals;
- fists;
- valve tappets and valve stems;
- leading gear of the exhaust camshaft.
After performing its functions, the oil returns to the sump under the force of gravity (by gravity).
To control the oil level in the crankcase, a dipstick is installed on one side of the oil pump housing.
Oil pump
The oil pump takes oil from the engine sump through the oil intake and delivers it under pressure to various friction units. The oil intake with a mesh filter is located in front of the oil pump inlet. The oil pump itself is a trochoid pump. Inside it are the leading and driven rotors with internal gearing, which rotate in the same direction. Since the axes of the leading and driven rotors are offset from each other, the space between both rotors changes as they rotate. Oil is sucked into the pump when the space between the rotors expands, and is pumped when the space between the rotors narrows.
Oil pressure regulator (pressure reducing valve)
At high rotation speeds, the amount of oil supplied by the oil pump is excessive compared to the amount required to lubricate the friction pairs. Oil pressure regulator (pressure reducing valve) prevents excess oil supply. At low rotation speeds, the regulator valve closes the bypass channel under the action of the spring. But at high rotation speeds, the oil pressure increases sharply, the force of the oil pressure overcomes the force of the spring, and the regulator valve opens. Excess oil returns to the sump through the valve.
Oil filter
Oil filter - full-flow type with replaceable paper filter element. Metal particles (wear products), airborne dirt particles, carbon particles and other types of contaminants can enter the oil during use, causing increased engine wear or clogging (narrowing of channels) oil lines, preventing the circulation of oil. An oil filter installed in the oil line allows these particles to be retained as the oil passes through it. The filter is installed on the outside of the engine, which makes it relatively easy to replace the filter element. A bypass valve is installed in front of the filter element, which opens when the pressure in front of the filter increases, which occurs when the filter element is clogged with contaminants. The bypass valve opens when the oil pressure force exceeds the force of the valve spring. In this case, the oil passes through a bypass channel, bypassing the oil filter, and is directed directly into the main oil line of the engine.
(The text is taken from the specified website: «Toyotaman.ru»)