A turbocharger is actually an air compressor that compresses air to increase the amount of incoming air. It uses the inertial momentum of the exhaust gas from the engine to push the turbine in the turbine room, and the turbine drives the coaxial impeller, which presses the air sent by the air filter pipe to pressurize it into the cylinder. When the engine speed increases, the exhaust gas discharge speed and turbine speed also increase synchronously, and the impeller compresses more air into the cylinder. The increase of air pressure and density can burn more fuel, and the corresponding increase of fuel quantity and adjustment of engine speed can increase the output power of the engine.

Structure principle

First of all, about the structure of the turbocharger, exhaust gas turbocharger is mainly composed of pump wheel and turbine, of course, there are some other control components. The pump wheel is connected to the turbine by a shaft, the rotor. Exhaust gas from the engine drives the pump wheel, which turns the turbine, which pressurizes the intake system. Turbocharger installed on the exhaust side of the engine, so the working temperature of the supercharger is very high, and the supercharger rotor speed at work is very high, can achieve the similar RPM, high rotation speed and temperature makes common mechanical needle or ball bearing cannot work for the rotor, so the whole floating bearing widely used turbocharger, the engine oil for lubrication, There is also coolant for the supercharger cooling. In the past, turbochargers are mostly used in diesel engines, because gasoline and diesel combustion methods are not the same, so the engine with a turbocharger form is also different. Gasoline engine is different from diesel engine, it is not air into the cylinder, but the mixture of gasoline and air, too much pressure is easy to deignite. Therefore, the installation of turbochargers must avoid deflagration, which involves two related issues, one is high temperature control, the other is ignition time control.

After forced pressurization, the temperature and pressure of gasoline engine compression and combustion will increase, and the deflagration tendency will increase. In addition, the exhaust temperature of gasoline engine is higher than that of diesel engine, and it is not suitable to increase the overlap Angle of the valve (the time when the inlet and exhaust doors open at the same time) to strengthen the cooling of the exhaust, and reduce the compression ratio will cause inadequate combustion. In addition, the speed of gasoline engine is higher than that of diesel engine, and the change of air flow is large, which is easy to cause the turbocharger reaction lag. In view of a series of problems in the use of turbocharger in gasoline engines, engineers have made specific improvements one by one, so that gasoline engines can also use exhaust gas turbocharger.

Cold machine

The temperature increases, which not only affects the inflation efficiency, but also easily produces deflagration. Therefore, it is necessary to install the equipment to reduce the intake temperature, which is the intercooler. It is installed between the outlet of the turbocharger and the inlet pipe to cool the air entering the cylinder. An intercooler is like a radiator. It is cooled by wind or water, and the heat of the air escapes into the atmosphere by cooling. According TO THE test, THE good performance of the intercooler can not only make the engine compression ratio can maintain a certain value without deflation, but also reduce the temperature can improve the intake pressure, further improve the effective power of the engine.

The impeller

Due to the wide speed range of the gasoline engine and the large variation of air flow, the appearance of the compressor impeller of the turbocharger is a complex three-way curved ultra-thin-walled impeller, which generally has 12 to 30 blades, arranged in a radial linear curve, and the blade thickness is below 0.5 mm. It is made of aluminum by special casting method. The shape of the blade directly affects the performance of the turbocharged engine. The more reasonable the impeller shape Angle, the lighter the weight, the more sensitive the impeller start, the turbocharger's inherent defect "reaction lag" is also smaller.

Deflagration sensor

In addition to lowering the temperature to reduce the possibility of deflagration outside, but also knock transducer, and its role is in produce deflagration, feel abnormal vibration sensor information feedback immediately to the engine ECU (electronic control unit) control system, will be slightly delayed ignition timing, do not produce deflagration back to normal when the ignition timing.

Other

Because the speed of car gasoline engine is higher than that of diesel engine, the air flow rate is fast and the range of change is large, so its turbocharger has higher requirements. Electronic injection system has been widely used in modern car engines. With the cooperation of electronic control technology and new materials, turbochargers will be increasingly widely used in gasoline engines.

Exhaust gas turbochargers used in cars all adopt single inlet turbine housing, that is to say, only the pressure energy of exhaust gas exhaust is used, and no other auxiliary energy is needed. Due to the large speed range of car engine, the exhaust gas turbocharger must be equipped with a regulating device, so that the engine can obtain a relatively constant pressurization pressure within a certain speed range. In addition, gasoline engine is ignited ignition, its compression ratio is limited in a certain range, too high will cause deflagration. Therefore, there should be deflagration detection and control mechanism to adjust the ignition advance Angle at any time.

The exhaust gas turbocharger of the car is generally installed near the exhaust pipe, and the turbine and impeller are respectively installed in the turbine room and supercharger. The two are coaxial rigid connection and synchronous rotation.

When pressurization is not required, such as at idle or when there is a threat of deflagration, a portion of the exhaust escapes through the bypass valve and does not enter the turbocharger. When the engine reaches 2,000 revolutions per minute, the solenoid valve closes the bypass valve and directs the exhaust flow to the turbine side, turning the turbine. Another design is to adjust the Angle of the turbine blade and adjust the speed of the turbine through the change of the resistance, so as to change the boost amount.

Cooling the air causes it to shrink, increase density, cram more air into the same volume, and prevent deflagration. Therefore, turbochargers of cars are equipped with intercoolers, which are generally cooled by air, installed in front of the engine radiator, next to it or in a separate position, and cooled by the car's head-on air flow or its own fan.

The key component of turbocharger is bearing. This type of bearing named according to the lubrication form is called "full floating bearing", the working speed is very high, the working environment is bad. Therefore, it is very important to ensure lubrication. If the oil supply is slow due to low oil pressure, the bearing will be damaged and the turbocharger will fail. This kind of failure will not occur in normal engine starting, but if the engine starts for the first time after changing the oil and oil filter, it will produce slow oil supply phenomenon, so that the bearing lacks oil lubrication. In this case, after starting to idle for about 3 minutes, can not directly increase the speed to the start speed of the turbocharger. Similarly, do not make the engine stop immediately after high speed and uphill, to make the engine continue to idle for about 1 minute, so that the turbocharger bearing will not lack of oil. Therefore, the driver of the turbocharger car must follow the instructions of the manufacturer, and pay great attention to the quality of the oil. It is not appropriate to operate the turbocharger car as a general car.

Points for attention:

Since the turbocharger often works at high speed and high temperature, the temperature of the turbocharger exhaust gas turbine end is about 600℃, and the rotor of the supercharger rotates at a high speed of 8000-11000R /min. Therefore, in order to ensure the normal work of the supercharger, the following points should be paid attention to in use:

Don't start the engine then drive right away

After the engine is started, especially in winter, it should be allowed to run at idle speed for a period of time so that the lubricating oil can fully lubricate the bearing before the supercharger rotor runs at high speed. So just after the start of the must not blast the throttle, in order to prevent damage to the supercharger oil seal. Do not turn off the engine immediately after running for a long time at high speed. When the engine is working, a part of the oil is supplied to the turbocharger rotor bearings for lubrication and cooling. After running the engine suddenly stop, oil pressure rapidly reduced to zero, the supercharger turbo spread to middle part of the high temperature and bearing shell heat cannot take away quickly, while the turbocharger rotor was still under the effect of inertia at high speed, therefore, if all of a sudden stop, the engine heat engine condition will cause the turbocharger stranded within the oil overheating and damage of bearing and shaft. In particular, to prevent the sudden flameout after a few feet of the throttle.

Keep clean when removing the supercharger, to keep clean, the pipe joint must be plugged with a clean cloth, to prevent debris into the supercharger, damage to the rotor. Attention should be paid not to damage the impeller during maintenance. If the impeller needs to be replaced, the dynamic balance test should be done. After reloading, remove the plug.

To be cleaned

Because the supercharger is often operated at high temperature, its lubricating oil pipeline due to high temperature, internal oil is easy to have part of the coking, which will cause insufficient lubrication of the supercharger bearing damage. Therefore, the lubricating oil line should be cleaned after a period of operation.

Pay attention to maintenance

Before the car and after the car, the connection of each airway pipe should be checked to prevent the failure of the supercharger caused by loosening and falling off and the air short circuit entering the cylinder.

It can be seen that after the engine is pressurized, the structure of the parts is strengthened. In terms of use and maintenance, it is necessary to strengthen the compulsory maintenance of the engine and pay attention to the correct operation method.

Fault handling

Turbocharger is an important component used to increase engine power and reduce exhaust emissions. Due to improper use, maintenance and maintenance, it is prone to failure, resulting in the engine can not work normally. In this paper, some common turbocharger faults and treatment methods are introduced as follows:

The spill

Phenomenon 1: 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.

Treatment method:

1. First of all, check whether the engine lubrication system external oil pipe (including the supercharger inlet and return pipe) leaks oil;

2. Check the supercharger exhaust outlet for oil. If there is oil, it can be determined that the seal ring at one end of the turbine is damaged, and this seal ring should be replaced.

Phenomenon two: large oil consumption, exhaust blue smoke, but the power does not decline.

Cause: Due to the leakage of the supercharger pressure end, the oil through the engine inlet pipe into the combustion chamber is burned off, there are the following possibilities:

1. The supercharger return pipe is not smooth, the oil in the middle of the rotor assembly support where the accumulation is too much, along the rotor shaft into the compressor impeller.

2. Close to the pressure gas impeller end of the sealing ring or oil ring damage, the oil into the impeller chamber, and then with the indoor pressurized air into the tube into the combustion chamber.

Treatment method:

1. Open the compressor outlet or engine intake straight pipe (rubber hose), watch the port, pipe wall adhesion oil. If yes, please check whether the supercharger return pipe is unblocked. If it is not smooth, it is caused by excessive oil accumulation at the middle support, and the return pipe should be dredged and reassembled.

2. Such as smooth, it is due to the impeller end sealing ring or oil ring damage caused by the disassembly of the supercharger repair.

Phenomenon three: large oil consumption, exhaust smoke blue or black smoke, and power decline.

The reason:

1. The gap between the piston and the cylinder is too worn and the oil escapes into the combustion chamber and burns off.

2. In the process of air inhalation by the supercharger, the air flow meets greater resistance. (such as air filter plug, air intake hose is suction deformation or flattening, etc.), the pressure at the compressor inlet is low, resulting in oil leakage into the compressor, with the compressed air into the combustion chamber to burn.

Treatment method:

1. Check whether there is oil in the wall of the inlet straight tube, whether it is flattened, so that the air flow is blocked or the air filter element is blocked.

2. If there is oil in the pipe mouth and wall, the air filter element should be cleaned or replaced.

There was the sound of metal scraping

Phenomenon: exhaust black smoke, power decline, and the supercharger has abnormal sound.

The reason:

1. If there is metal friction sound, is the supercharger rotor bearing or thrust bearing wear too much, impeller and supercharger shell friction.

2. If it is not metal friction sound, but the sound of air flow, it is due to the high-speed rotation of the supercharger rotor, the rotating sound generated, or the leakage phenomenon caused by the poor connection of the inlet and exhaust interface.

Treatment method:

(1) The former shall be repaired by replacing the damaged spare parts according to the wear condition.

2. The latter should be carefully differentiated and targeted solutions.

Bearing damage

Phenomenon: supercharger bearing damage, engine power decline, high oil consumption, black smoke, serious supercharger can not work.

The reason:

1. Insufficient lubricating oil pressure and flow.

A. Insufficient supply of lubricating oil for supercharger journal and thrust bearing;

B. Insufficient lubricating oil to keep the rotor journal and bearing floating;

C. The supercharger has been running at high speed, but the lubricating oil is not supplied in time.

2. Debris or sediment into the lubrication system.

3. Oil oxidation deterioration.

A. Diesel oil overheating, from the piston and cylinder wall channeling too much gas;

B. Cooling water leakage into the oil;

C. Improper oil selection and failure to change the oil regularly as required.

Treatment method:

1. Check whether the lubricating oil pressure is normal and the oil quantity meets the requirements.

2. According to the requirements of the regulations, change the lubricating oil regularly, and ensure the cleaning of lubricating oil.

3. In strict accordance with the requirements of the regulations, the use of lubricating oil, do not mix.

4. Avoid engine operating at high temperature and maintain normal engine operating temperature.

Maintenance error:

Mistake one: Change the oil at will

In the "drink" oil, turbochargers are indeed more "delicate", in addition to the amount of ordinary naturally aspirated engine is larger than some, the requirements for oil are higher. Because the design of turbocharger is different from that of naturally inspired engine, its main rotating shaft adopts floating design, and the main rotating shaft is filled with oil between the turbine body and the main rotating shaft. The whole main rotating shaft depends on lubricating oil for heat dissipation and lubrication, while the inferior oil has high viscosity and poor fluidity, so it cannot play a good role. It is recommended that the owner increase some investment in this area and replace the all-synthetic oil for the vehicle.

Misunderstanding two: to the destination immediately flameout

After a long time of high load operation, the owner must idle for a few minutes before shutting down the engine, so that the parts can be effectively cooled and lubricated. The behavior of immediately stalling the car will make the vehicle often in a high speed idling state, the problem is the same as sudden acceleration, will damage the bearing of the vehicle.

Mistake three: a start on the throttle

Can improve the speed in a short time is a major feature of turbocharged cars, but this does not mean that the owner can be rude to the car, in fact, just after the start of the throttle is easy to damage the supercharger oil seal. Turbocharged engine revolution is very high, after starting the vehicle, can not hurry to step on the accelerator pedal, should be idle for 3-5 minutes, so that the oil pump has enough time to transport the oil to each part of the turbocharger, at the same time, after the oil temperature slowly rises, the fluidity is better, at this time, the speed will be "like a duck to water".

The difference between twin and single turbines is:

1. Double turbine refers to two turbochargers, while single turbine has only one turbocharger;

2, the use of twin turbine bed expansion system from an independent turbocharger, mostly to alleviate the "lag phenomenon";

3. Turbocharging is single turbocharging, divided into mechanical turbocharging, exhaust turbocharging and compound turbocharging;

4. Turbo charging mainly uses turbo charging.

In daily life, we contact most is the single turbocharger. Its biggest advantage is low price, but at the same time there is the problem of "lag". Especially when the car is driving at low speed, when the exhaust is not enough to drive the turbine to drive the compressor, it is clear that there is some "meat" in the car. For high-end models, a single-turbine, double-vortex turbocharger can be installed, which is similar to a regular turbocharger but with the addition of a discarded pipe to reduce turbo lag. The existence of double turbine make up for the deficiency of the single turbo lag, using two independent turbocharger, the turbocharger of interference from the engine speed is decided by many factors, one of the most important is the turbocharger blade inertia, inertia small leaves decreased in speed, namely the vehicle at low speed can also drive the turbine.

YTM Motor produces turbochargers mainly in a variety of construction machinery and car engines.

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