Development of Capacitor Energy Storage High-speed Solenoid Valve Drive Circuit

Development of Capacitor Energy Storage Type High Speed u200bu200bSolenoid Valve Drive Circuit:

High pressure common rail fuel injection system is one of the development directions of diesel engines. The system ensures the engine's requirements for fuel injection timing, precise fuel injection volume and ideal fuel injection rate by controlling the common rail pressure of the fuel and the rapid opening and closing of the fuel injector. The key actuator is a high-speed solenoid valve, and its current response characteristics determine that its drive circuit should meet the following basic requirements.

1. The strong excitation of the energy before the solenoid control valve is opened. The power drive module should inject energy into the solenoid valve at the highest possible rate to ensure that the solenoid control valve generates enough electromagnetic force during the opening process to shorten the opening response time .

2. After the electromagnetic control valve is opened, because the working air gap is small, the magnetic circuit reluctance is very low, and the electromagnetic coil can generate a large enough electromagnetic force to ensure the reliability of the electromagnetic control valve with a small holding current. Turn on. A small holding current can reduce energy consumption, reduce coil heating, and at the same time facilitate the rapid closing of the solenoid control valve.

To sum up, the design of solenoid valve drive circuit requires that the corresponding ideal drive current be maintained during the different working stages of the solenoid valve.

Currently common solenoid valve drive circuits are roughly divided into four types: adjustable resistance type, dual voltage type, pulse width modulation type and dual voltage pulse width modulation type.

Among them, the adjustable resistance drive circuit has a simple structure but high power consumption, and the dual-voltage drive circuit has reduced power consumption but is still not ideal. Both the pulse width modulation type and the dual voltage pulse width modulation type use PWM to control the solenoid valve holding current, which greatly reduces the power consumption. Compared with the pulse width modulation type, the advantage of the dual voltage pulse width modulation type is that the solenoid valve maintains the current provided by the battery, which reduces the load of the DC/DC boost circuit.

However, the common problem of the above-mentioned driving circuits is that it is difficult to ensure the normal opening of the solenoid valve when the injection pulse width sequence overlaps. This is because when the two injection signals overlap in phase, the conduction of one of the solenoid valves will cause the voltage of the DC/DC boost circuit to drop instantaneously, and the voltage at this time will not be able to guarantee the normal opening of the other solenoid valve.

In the background of the subject of this article, the front and rear cylinders of the diesel high-pressure common rail rotor engine are equipped with dual injectors, that is, the pilot injector and the main injector are independently controlled, and the two injectors are partly working The injection timing overlaps. Therefore, it is necessary to design and develop a new type of drive circuit to ensure that the injector can work normally in this part of the situation, that is, to ensure the injection timing and precise injection volume.