EDGE AS. -HD 3564596 - Caterpillar

Illustration 1 g02388696
Turbocharger accumulator system (rear engine view) (1) Accumulator (2) Check valve (3) Tube (4) TurbochargerAccumulator (1) stores pressurized engine oil that is used for lubrication of turbocharger shaft bearings in turbocharger (4). Pressurized engine oil is supplied to the accumulator through tube (3) from the engine oil gallery. Check valve (2) prevents engine oil from flowing back into the crankcase after engine shutdown.
Illustration 2 g02389136
Cutaway of the accumulator (5) Oil chamber (6) O-ring seals (7) Piston (8) Dry nitrogen chamber (9) ValveThe accumulator consists of two main chambers that are separated by piston (7). O-ring seals (6) are used to seal the ends of the accumulator and to seal the piston between the chambers. The piston is allowed to move within the cylinder of the accumulator according to the amount of oil pressure that is placed on the system. Oil chamber (5) fills as the pressure of the engine oil rises and the pressure of the nitrogen gas is overcome. The dry nitrogen chamber (8) is pressurized with a charge of nitrogen gas prior to installation onto the engine. Valve (9) is used to service the accumulator by recharging the unit with nitrogen gas, as necessary.As the engine is cranked, engine oil pressure rises within the oil gallery of the engine. Pressurized oil from the oil pump is directed through the oil supply tube, through the check valve, into the accumulator. A quantity of pressurized engine oil is continuously stored in the accumulator during engine operation.The oil chamber accepts a variable amount of pressurized oil while the engine is running. The piston is moved in the cylinder by the differential pressures that exist between the two chambers. As the oil pressure from the engine overtakes the pressure of the nitrogen gas, the piston compresses the nitrogen gas. As the piston moves downward in the cylinder of the accumulator, a larger volume of oil flows into the oil chamber. An equilibrium between the pressure in the two chambers is created and potential energy is stored in the accumulator.When the engine shuts down, the pressure of the nitrogen gas overcomes the reduced engine oil pressure. The piston is pushed upward by the potential energy stored in the nitrogen gas and the oil is forced out of the upper chamber. As the oil line to the turbocharger is pressurized by the accumulator, the check valve closes off the oil supply line to the oil gallery. The volume of engine oil that is stored in the accumulator flows directly to the turbocharger shaft bearings for lubrication. After lubricating the turbocharger shaft bearings, the oil drains into the crankcase through tubing into the rear housing.