Velocity density method and throttle speed method

According to the air quantity detection method, it is necessary to measure the air quantity entering the engine to classify the electronically controlled gasoline injection system. According to the different ways of detecting the amount of inhaled air, it can be divided into direct and indirect categories:

1, direct detection mode is also called mass flow mode;

(1) mass flow mode. There are L-type (volume type) and LH-type sensors for directly measuring the volume or mass of air entering the cylinder. L-type sensor has vane air flow sensor or Kalman vortex air flow sensor. By measuring the amount of air entering the cylinder, the physical quantity is converted into an electrical signal and sent to the ECU, and the ECU calculates the fuel injection amount corresponding to the amount of air. Bosch Company calls this type L-Jetronic electronically controlled gasoline injection system. LH sensor is a hot-wire or hot-film air flow sensor, which directly measures the air quality entering the cylinder and converts it into an electrical signal and sends it to ECU, which controls the corresponding fuel injection quantity to ensure the best air-fuel ratio.

2. Indirect detection methods can be divided into speed-density method and throttle-speed method.

(1) Velocity-density model. This method uses the relationship between engine speed and intake pipe pressure to measure the amount of air sucked into the cylinder, and then controls the fuel injection amount.

(2) Throttle speed mode. In this way, the amount of air sucked into the cylinder is measured according to the throttle opening and engine speed, and then the fuel injection amount is controlled. However, due to the complex functional relationship between air volume and throttle opening and speed, it is difficult to measure accurately, and this control method is basically eliminated.