Common faults and treatment methods of automobile engine turbochargers?

Update:17-06-2021
Summary:

Automobile engine exhaust gas turbocharger (hereinafter […]

Automobile engine exhaust gas turbocharger (hereinafter referred to as supercharger) is a very sophisticated device, which is widely used in power equipment such as engineering machinery and generator sets. On the basis of not changing the basic structure of the diesel engine, the supercharger can increase The power is 30% or more, which reduces fuel consumption by about 5%, and receives good economic benefits. However, the supercharger often fails to achieve the expected use effect due to improper installation and use during its use. Now, based on the structural principle of the supercharger, the common faults of the supercharger are analyzed.

The supercharger uses the exhaust gas discharged from the exhaust pipe to drive the turbine to rotate at a high speed. At the same time, the compressor impeller is driven to rotate at a high speed through the rotor shaft. Its speed can reach 50000~230,000r/min. The high-speed rotating compressor impeller increases the intake air. Pressure, the density of the air entering the cylinder is greatly increased, and the power of the diesel engine is improved. Turbocharger is an important part used to increase engine power and reduce exhaust emissions. Due to improper use, maintenance and maintenance, it is easy to malfunction and cause the engine to fail to work normally. This article introduces some common faults and treatment methods of turbochargers as follows:

  1 The turbocharger leaks oil
   Phenomenon 1: The oil consumption is large, but the exhaust smoke is normal and the power is not reduced.
   Reason: This situation is generally caused by oil leakage.

Approach:
   (1) First, check whether the external oil pipes of the engine lubrication system (including the inlet and return pipes of the turbocharger) are leaking;
   (2) Check whether the exhaust gas outlet of the turbocharger is organic oil. If there is organic oil, it can be judged that the seal ring at one end of the turbine is damaged, and the seal ring should be replaced.

   Phenomenon 2: High oil consumption, blue smoke from exhaust, but no drop in power.
   Reason: Due to the oil leakage at the compressor end of the turbocharger, the engine oil enters the combustion chamber through the engine intake pipe and is burned. There are several possibilities:
   (1) The oil return pipe of the turbocharger is not unblocked, and the oil accumulates too much in the middle support of the rotor assembly, and flows into the compressor impeller along the rotor shaft.
   (2) After the seal ring or oil slinger near the end of the compressor impeller is damaged, the oil enters the impeller chamber from this, and then enters the combustion chamber through the inlet tube along with the pressurized indoor air.

Approach:
   (1) Open the air outlet of the compressor or the straight pipe (rubber hose) of the engine's air intake, and check whether the oil is adhered to the nozzle or the pipe wall. If yes, please check if the return pipe of the turbocharger is unblocked. If it is not unblocked, it is caused by excessive oil accumulation at the intermediate support. The oil return pipe should be dredged and reinstalled.
   (2) If it is unblocked, it is caused by damage to the seal ring or slinger ring at one end of the impeller, and the supercharger should be disassembled for repair.

   Phenomenon 3: Large oil consumption, blue smoke or black smoke from exhaust, and power drop.
the reason:
   (1) The gap between the piston and the cylinder is worn too much, and the oil rushes into the combustion chamber and is burned.
   (2) In the process of air being sucked in by the supercharger, the air flow encounters greater resistance. (Such as the air filter is blocked, the air inlet hose is sucked and deformed or flattened, etc.), the pressure at the air inlet of the compressor is low, causing oil to leak into the compressor and enter the combustion chamber along with the compressed air to be burned.

Approach:
   (1) Check whether there is inorganic oil in the wall of the straight air inlet hose and whether it is squashed, so that the air flow is blocked or the air filter element is blocked.
   (2) If the pipe mouth and pipe wall have organic oil, the air filter element should be cleaned or replaced.
  2 There is a metal rubbing sound

   Phenomenon: black smoke from exhaust, power drop, and abnormal noise from the supercharger.
the reason:
   (1) If there is a metal friction sound, it is caused by the excessive wear of the turbocharger rotor bearing or thrust bearing, and the friction between the impeller and the turbocharger shell.
   (2) If it is not the sound of metal friction but the sound of airflow, it is the rotating sound produced by the high-speed rotation of the turbocharger rotor, or the air leakage caused by the poor connection at the inlet and exhaust ports.

Approach:
   (1) The former should be repaired by replacing damaged spare parts according to wear and tear.
   (2) The latter should be carefully distinguished and targeted solutions.

  3 Supercharger bearing is damaged
   Phenomenon: the supercharger bearing is damaged, the engine power is reduced, the oil consumption is high, black smoke is emitted, and the supercharger cannot work in severe cases.
the reason:
   (1) Lubricating oil pressure and flow are insufficient.
  A. Insufficient lubricating oil supply for turbocharger journals and thrust bearings;
  B. There is insufficient lubricating oil to keep the rotor journal and the bearing floating;
  C. The turbocharger has been running at high speed, but the lubricating oil has not been supplied in time.
   (2) Sundries or sand enter the lubrication system.
   (3) The engine oil is oxidized and deteriorated.
  A. Diesel engine oil is overheated, and too much gas is passing between the piston and the cylinder wall;
  B. Cooling water leaks into the oil;
  C. Improper selection of engine oil, and failure to change engine oil regularly as required.
Approach:
   (1) Check whether the lubricating oil pressure is normal and whether the oil quantity meets the requirements.
   (2) Regularly replace the lubricating oil according to the specified requirements and ensure that the lubricating oil is clean.
   (3) Use lubricating oil in strict accordance with the regulations and do not mix them.
   (4) Avoid working the engine at high temperatures and maintain the engine's normal operating temperature.

   If the above phenomenon occurs, disassemble the turbocharger for cleaning and replace the corresponding parts. When oil leakage of the turbocharger is found, it is necessary to check whether the return pipe of the turbocharger and the ventilation pipe of the diesel engine are blocked, and whether the oil cooler is working properly. When the engine oil is found to be sludge-like, the engine oil and the engine oil filter should be replaced immediately in accordance with the regulations. Only in this way can the turbocharger be eliminated and ensure that it works in good conditions.

  4 Shorten the service life of the turbocharger

   (1) The installation is incorrect. According to the requirements, when installing the turbocharger, the floating bearing should be filled with oil first to avoid that the oil cannot be supplied to the floating bearing in time when the engine is started, causing dry grinding and damaging the floating bearing.
   (2) Incorrect startup. After the supercharged engine is started, it must be idle for a few minutes to ensure that the supercharger can run at high speed after the oil reaches the floating bearing.
   (3) The shutdown is incorrect. Before stopping, run at idle speed for a few minutes to make the supercharger rotor gradually decelerate and cool down. When the engine stops suddenly, the oil supply stops, and the rotor rotates at a high speed under the action of inertia. At this time, the floating bearing will wear out due to the high temperature and lack of oil, or even ablate.
   (4) The oil selection is incorrect. The thermal load and mechanical load of the engine equipped with a supercharger are greatly increased. The lubricating oil is required to have good viscosity-temperature characteristics, oxidation resistance and wear resistance, and good quality oil must be selected.
In view of the above failures, when installing and using the turbocharger, you should strictly follow the instructions for the correct operation; regularly check and clean the air filter to ensure unobstructed air intake; regularly remove the sludge on the compressor impeller, and check the turbocharger at the same time The use of the compressor impeller fixing screws and blades at the price of the actuator can prevent the impeller from falling off and causing major accidents; use the oil from the regular manufacturer that meets the use standards, and operate the engine start and stop in accordance with the operating procedures to avoid long-term idling of the engine.

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