What is the function of the exhaust bypass valve on the turbocharger? What are its control methods?

2019-10-08 14:00:45

Nowadays, more and more small displacement turbocharged engines are used in automobiles. Its advantage is that the engine power and torque can be greatly increased without increasing engine displacement. The price of turbocharger actuator is also appropriate. But the turbocharger also has a lot of shortcomings: at low speed, the turbocharger is insufficient and the turbocharger is hysteretic; at high speed, the turbocharger will be over-charged. In order to overcome such shortcomings, bypass valves are designed on the supercharger to control the supercharger pressure.


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1. The working principle of bypass valve turbocharger:


At high speed and high load, the bypass valve of turbocharger opens, some exhaust gas enters the exhaust pipe directly through the bypass valve, releases some exhaust gas, and reduces the turbine speed, so as to control the pressure of turbocharger.


There are two control modes of bypass valve turbocharger, one is mechanical (vacuum) control, which is usually used in truck diesel engines, the other is electronic control, which is usually used in cars.


2. Structure and Working Principle of Mechanical Control Bypass Valve


Mechanical control bypass valve mainly consists of control chamber, pull rod, bypass valve and so on. The left side of diaphragm in bypass valve actuator passes through pressurized gas.


1. When the engine runs at low speed, the compressor outlet pressure is low. The bypass valve closes under the action of the return spring. The exhaust gas from the engine passes through the turbocharger's turbine end, which improves the turbocharger's speed, generates a larger intake pressure, improves the intake volume and improves the low-speed performance of the engine.


2. When the engine runs at high speed, the burst pressure after supercharging exceeds the prescribed value. The supercharged gas lifts the diaphragm in the exhaust actuator, drives the pull rod of the bypass valve to move, and opens the exhaust bypass valve. Therefore, some exhaust gases are discharged directly from the exhaust bypass without passing the turbocharger turbine end, so that the turbine inlet flow is made. Reduce the volume, pressure, turbocharger speed, reduce the pressure of the turbocharger.


3. Structure and Working Principle of Electronic Control Bypass Valve


The opening and closing of the exhaust bypass valve is controlled by the boost pressure control solenoid valve controlled by the ECU of the electronic control unit. The ECU monitors the working condition of the engine and compares it with the internal preset parameters to control the opening time of the solenoid valve, so as to change the opening of the exhaust bypass valve, control the exhaust bypass flux and regulate the pressurization pressure.


4. Notes for the use of bypass valve turbochargers:


1. The pre-tightening pressure setting and calibration of the spring in the bypass valve actuator are carried out on the equipment specially designed and calibrated by the manufacturer. The user can not adjust and change at will.


2. Do not use the push rod outside the bypass valve supercharger assembly as a handle to move the supercharger assembly, so as to avoid affecting the sensitivity and reliability of the bypass valve actuator.


WUXI SHENGYI TURBO is a professional enterprise producing turbocharger and turbo repair partshas more than 300 turbocharger models for vehicles application as Garrett, Hitachi, Toyota, Mitsubishi, Benz, BMW, Audi, Ford, Jeep, Dongfeng .etc. Our turbochargers offer direct replacements to OEM models, also offer customized solutions to our customers. We adopt vanguard technology positively from home and abroad, and have established the long-term technical cooperation with many well-known enterprises. We have passed ISO9001:2000 in September, 2004. Now we own the floor space 5800 square meters. There are more than 50 workers including more than 10 technical staff who has the senior or intermediate title and more than 30 first-line workers who have rich experience in turbocharger. For more information please contact us info@syturbo.com

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