Working principle of bypass valve of automobile turbocharger
Working principle of bypass valve of automobile turbocharger
First, the working principle of the bypass valve turbocharger:
At high speed and high load, the bypass valve of the turbocharger accessories is opened, part of the exhaust gas directly enters the exhaust pipe through the bypass valve, part of the exhaust gas is released, and the turbine speed is reduced, thereby controlling the supercharging pressure. There are two control methods for bypass valve turbochargers, one is mechanical (vacuum) control, which is usually used in truck diesel engines; the other is electronic control, which is usually used in cars.
Second. The structure and working principle of mechanical control bypass valve type:
The mechanically controlled bypass valve is mainly composed of a control air chamber, a pull rod, a bypass valve, etc. The left side of the diaphragm of the bypass valve actuator passes the pressurized gas.
1. When the engine is running at low speed, the outlet pressure of the compressor is low, the bypass valve is closed under the action of the return spring, and all the exhaust gas discharged from the engine passes through the turbine end of the supercharger, thereby increasing the speed of the turbine, which can generate The larger intake boost pressure increases the intake air volume and improves the low-speed performance of the engine.
2. When the engine is running at high speed, the supercharged intake pressure exceeds the specified value, and the supercharged gas lifts the diaphragm in the exhaust actuator, drives the bypass valve rod to move, and opens the exhaust bypass valve, so Part of the exhaust gas does not pass through the turbine end of the supercharger, and is directly discharged into the atmosphere from the exhaust bypass channel, which reduces the inlet flow of the turbine, the pressure, and the speed of the supercharger, reducing the supercharging pressure.
Third. The structure and working principle of the electronically controlled bypass valve type:
The opening and closing of the exhaust bypass valve is controlled by the boost pressure control solenoid valve controlled by the electronic control unit ECU. The electronic control unit ECU monitors the working condition of the engine, compares it with the internal preset parameters, and controls the opening time of the solenoid valve accordingly, so as to change the opening of the exhaust bypass valve, control the exhaust bypass flow, and accurately. The purpose of regulating boost pressure.
