Description of the mechanical part of Mazda RF-CDT, MZR-CD engines
The RF-CDT and MZR-CD engines are in-line, four-cylinder, 16-valve diesel engines with an overhead camshaft and liquid cooling. Engine capacity – 2.0 liters. The numbering of the cylinders is from the crankshaft pulley.
The MZR-CD engine is based on the RF engine and is a modification of it. The release of this generation of engines began in June 2002, they were first installed on Mazda 6 (first generation) and Mazda MPV (second generation) cars..
The main distinguishing feature of this generation of engines was the use of Denso Common Rail systems and a variable geometry of the blades on them..
This description is for the RF-CDT engine. MZR-CD engine may have design differences.
The steel crankshaft is five-bearing with eight counterweights mounted on the extension of the crankshaft cheeks. Oil is supplied to the crankshaft main journals from the side of the cylinder block. Oil is supplied to the crank pins of the crankshaft through channels from the main journals.
On the toe of the engine crankshaft, a gear pulley of the timing gear drive, an oil pump drive gear and mounted drive pulley is installed. Thrust half rings are installed in the support of the third root neck. The main bearing caps are made separate. Main bearing shells made of aluminum alloy.
Crankshaft. 1 – gear wheel of the oil pump drive, 2 – upper bearings of the main bearings, 3 – upper thrust half ring, 4 – the lower thrust half ring, 5 – lower bearings of the main bearings, 6 – covers of the main bearings, 7 – fillet.
1 – bushing of the upper head of the connecting rod, 2 – connecting rod,
3 – the upper liner of the connecting rod bearing,
4 – the bottom liner of the connecting rod bearing,
5 – installation pins, 6 – mounting bolts,
7 – a cover of the lower head of a rod.
The cylinder block is cast iron. The wall thickness of the cylinder block is reduced, and the stiffness of the cylinder block is increased by increasing its height. The cylinder block is sleeveless. In order to improve cooling and reduce oil consumption due to burnout, cross-shaped channels are made in the cylinder block through which coolant circulates, and oil channels are also provided in the cylinder block for lubricating the crankshaft, connecting rods, pistons, oil supply to the oil nozzles and to the cylinder head.
Connecting rods and pistons
The connecting rods of this engine are made of carbon steel stamping. Mounting pins are made in the cover of the lower head of the connecting rod for proper installation of the cover.
Connecting rod bearing shells are made of aluminum alloy having good anti-corrosion properties and fatigue resistance characteristics.
The pistons of this engine are made of aluminum alloy with good parameters of heat resistance and thermal conductivity. The combustion chamber is undivided, w – shaped, made by a groove in the piston head. The piston pin is made of special steel. Channels for cooling the piston are made in the piston head. Special cast inserts are installed in the piston that prevent thermal expansion of the piston, making it possible to make a minimum clearance between the cylinder and the piston.
To reduce weight and improve thermal conductivity, the cylinder head is made of aluminum alloy. Single camshaft timing (SOHC). A dynamic vibration damper is mounted on the camshaft pulley. Timing is driven by a timing belt from the crankshaft. The valve is driven from the camshaft through the rocker arms and axles. Valves are made of heat resistant steel. A groove is made on the exhaust valve to remove soot from the walls of the valve guide sleeve. Valve guides are cast from cast iron, which helps to reduce wear. The guide bushings of the intake and exhaust valves are the same. Valve springs have turns with the same pitch along the entire length.
To reduce vibration and better sound insulation, the cylinder head cover and the cap support are made of aluminum alloy. A camshaft position sensor is installed at the front of the cylinder head cover support.
Timing gear drive. 1 – tensioner pulley, 2 – race pulley-
camshaft, 3 – timing belt, 4 – camshaft,
5 – rocker arm, 6 – valve drive axle, 7 – fuel pump pulley, 8 – intermediate roller, 9 – crankshaft gear pulley, 10 – timing belt tensioner, 11 – coolant pump pulley, 12 – nozzle hole.
1 – oil filler cap, 2 – camshaft position sensor.
In the cylinder head, to improve the air supply to the cylinders and to clean the cylinders, two inlet and outlet ports for each cylinder are made. The geometry of the inlet ports is optimally selected to ensure sufficient turbulence in the air flow over the entire range of crankshaft rotational speeds and to reduce pumping losses at the inlet, which helps to improve the completeness of fuel combustion.
These engines use a closed-type liquid cooling system with forced circulation of coolant. The coolant pump is driven by a timing belt.
The thermostat with a bypass valve is located in the inlet pipe of the coolant and is designed to maintain the optimum temperature in the cooling system by letting the coolant in a small or large (through the radiator) cooling circle.
The engine uses a lubrication system with full-flow oil cleaning and with the supply of oil under pressure to the main moving parts and components of the engine.
Trochoid type oil pump. Inside it are located leading and driven rotors with internal gearing, which rotate in one direction. The drive is carried out from the gear mounted on the crankshaft.
Cooling system diagram.
Lubrication system diagram.
The oil filter is attached to the oil cooler and is located vertically below. An oil cooler is installed between the cylinder block and the oil filter to reduce the temperature of the oil and extend the life of the engine oil in the engine lubrication system.
Bushin Sergey, Legion-Avtodata
© 1999 – 2010 Legion Avtodata
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