Flow of engine oil from the accumulator
Accumulator (1) provides lubrication to the turbochargers' bearings during shutdown when the engine oil pressure is reduced but the turbocharger's wheels are still rotating. This helps increase the service life of the turbochargers.
After start-up, engine oil pressure rises and pressurized oil from the engine block flows upward through adapter (2). Some of the oil flows through tubes and hoses to both turbochargers. The remainder of the oil flows through a hose to the accumulator.
The accumulator has a chamber (3) that is filled with nitrogen gas. Valve (4) is used to fill the chamber and the valve is used to measure the pressure in the chamber.
Piston (5) is moved by differential pressures. Nitrogen gas in the upper part of the chamber pushes down on the piston. During engine operation, the engine oil pressure becomes greater than the nitrogen gas pressure. Pressurized engine oil pushes the piston upward. The lower portion of the chamber fills with oil until the pressure of the oil and the pressure of the nitrogen gas are equalized.
The piston's outer diameter is sealed in order to prevent the flow of gas or oil between the upper and lower portions of the chamber. The lower portion of the chamber remains filled with oil during engine operation.
When the engine shuts down, the pressure of the nitrogen gas becomes greater than the pressure of the engine oil. The piston is pushed downward and the oil is forced out of the chamber back through the adapter.
The adapter has a check valve that closes the oil passage from the cylinder block. This prevents the oil from draining into the cylinder block. The oil is directed to both turbochargers. After the turbocharger bearings are lubricated, the oil drains from the turbochargers into the rear housing.
Oil from the accumulator continues to lubricate the turbochargers until the nitrogen gas pushes the piston to the fully downward position and the supply of oil from the chamber is exhausted.