How to achieve stable power output for automotive components (high-pressure common rail components)
The high-pressure common rail system relies on the collaborative cooperation of various core components to ensure stable power output of the engine under different operating conditions through stable oil pressure, correct injection control, and other methods. The functions and collaborative working principles of each component are as follows:
The high-pressure common rail system relies on the collaborative cooperation of various core components to ensure stable power output of the engine under different operating conditions through stable oil pressure, correct injection control, and other methods. The functions and collaborative working principles of each component are as follows:
1. High pressure oil pump: stable oil supply, suitable for working conditions and requirements
High pressure fuel pumps often use three cylinder radial piston pumps, which can generate high-pressure fuel up to 135MPa. Its fuel supply design will meet the various operating conditions of the engine, such as the fluctuation demand of fuel supply during starting and acceleration. And it adapts to the working conditions through pressure regulating solenoid valves and oil pressure unit control. When the fuel injection quantity is small, one oil pressure unit will be closed to reduce the fuel supply, which not only avoids power loss but also stabilizes the fuel supply pressure. At the same time, its oil pressure cam is designed according to the principle of low peak torque, with even load, which not only reduces operating noise but also ensures a smooth oil supply process, laying the foundation for stable power.
2. Common rail chamber (common rail pipe): stabilize oil pressure and eliminate pressure fluctuations
The common rail chamber is equivalent to the "accumulator" of high-pressure fuel, which can store the fuel delivered by the high-pressure fuel pump and eliminate pressure fluctuations, controlling pressure fluctuations below 5MPa. It separates the generation of fuel injection pressure from the injection process, decoupling the pressure inside the high-pressure fuel pipe from the engine speed. Regardless of whether the engine is idling at low speed or running at high speed, the common rail chamber can maintain a stable high pressure, solving the problem of large changes in fuel supply pressure with speed in traditional diesel engines, ensuring stable fuel injection pressure under various operating conditions, and thus ensuring smooth power output. In addition, the pressure sensor on the common rail pipe will monitor the pressure in real time, and the pressure limiter can quickly release pressure when the pressure is abnormal, further ensuring stable oil pressure.
3. Electronic fuel injector: correctly controlling injection and optimizing combustion efficiency
This is a key component to ensure power stability, controlled by the ECU, and the injection related parameters are correctly controlled through the opening and closing of the solenoid valve. On the one hand, it can achieve flexible coordination of pre injection, main injection, and post injection. Pre injection can preheat the combustion chamber, shorten the ignition delay period of main injection, reduce engine vibration, and improve cold start performance; The main injection adjusts the rate to complete combustion within the effective crankshaft angle, ensuring power output; Post injection can promote secondary combustion and improve combustion adequacy. On the other hand, the control chamber volume and control orifice are designed correctly, which allows the needle valve to respond quickly, achieve rapid fuel cut-off, avoid incomplete fuel combustion, ensure power stability, and reduce power waste. At the same time, the extremely small spray holes can improve the fuel atomization effect, and with a suitable combustion chamber structure, it can make combustion more uniform and avoid power fluctuations caused by uneven combustion.
4. High pressure oil pipe: Balanced oil supply, reducing pressure loss
The high-pressure oil pipe, as a channel connecting the common rail pipe and the fuel injector, has strict design standards. The length of the high-pressure oil pipes in each cylinder should be as equal and as short as possible, so that each injector can obtain the same injection pressure, reduce the deviation of injection quantity in each cylinder, and avoid power imbalance caused by insufficient or excessive fuel supply in individual cylinders. At the same time, it can withstand high-pressure fuel shock, ensuring rapid establishment of common rail pressure during start-up, reducing pressure drop and pressure fluctuations during fuel flow, ensuring stable fuel delivery process, and assisting in synchronized power output of each cylinder.
5. Electronic Control Unit (ECU) and Sensors: Intelligent Control, Real time Adaptation to Operating Conditions
ECU is equivalent to the "brain" of the entire system, equipped with various sensors to receive real-time engine operating signals, such as speed, load, etc., and quickly calculate fuel injection parameters. It controls the fuel injection quantity correctly by controlling the opening time of the injector solenoid valve, and can also adjust the injection timing and the interval between pre injection, post injection, and main injection. For example, when operating at low speeds and low loads, adjust to a suitable small fuel injection quantity and injection rhythm; When operating at high speeds and high loads, increase the fuel injection quantity and optimize the injection rate to ensure that the engine can achieve matching power output under different operating conditions and maintain a stable state at all times.
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