How to adjust the pressure of turbocharger?

It is the simplest, lowest cost and very effective method to set the intake and exhaust bypass valve in the automobile turbocharger system. Controlling the diaphragm in the diaphragm box to divide the diaphragm box into an upper chamber and a lower chamber, wherein the upper chamber is an air chamber and is communicated with the outlet of the compressor through a communication pipe; The lower cavity is a diaphragm spring cavity, the diaphragm spring acts on the diaphragm, and the diaphragm is connected with the exhaust bypass valve through a connecting rod. When the outlet pressure of the compressor, that is, the boosting pressure, is lower than the limited value, the diaphragm moves up under the action of the diaphragm spring and drives the connecting rod to close the exhaust bypass valve; When the boost pressure exceeds the limit value, the boost pressure overcomes the diaphragm spring force, pushes the diaphragm downward, and drives the connecting rod to open the exhaust bypass valve, so that part of the exhaust gas directly enters the exhaust manifold without passing through the turbine, thus achieving the purpose of controlling the boost pressure and the turbine speed.

On some engines, the opening and closing of the exhaust bypass valve is controlled by a solenoid valve, which is controlled by an electronic control unit. According to the working condition of the engine, the electronic control unit determines the target boost pressure from the pre-stored boost pressure map, compares it with the actual boost pressure detected by the boost pressure sensor, and then changes the duty ratio of the pulse signal according to the difference to control the opening and closing of the solenoid valve, thereby changing the opening time of the solenoid valve, further changing the opening of the exhaust bypass valve and controlling the exhaust bypass flow, thus accurately adjusting the boost pressure. Exhaust bypass valve has been widely used in turbocharged automobile engines.

The exhaust energy of ordinary turbocharged engine at full load is very considerable, but at low engine speed, the exhaust energy is pitiful. At this time, the turbocharger cannot reach the working speed due to insufficient driving force. In this way, the turbocharger will not work at low speed, and the dynamic performance of the turbocharged engine will even be worse than that of the naturally aspirated engine with the same displacement. This is the phenomenon of turbine hysteresis.