The valve timing adjustment mechanism of automobile engines, also known as the continuously variable valve timing system, is an important technology in the field of modern automobile engineering.
1. This system has been widely used in high-performance engines. Through a sophisticated control and execution system, it can adjust the phase of the engine cam or the valve lift to optimize the engine's valve timing process.
2. The timing angle of the valve has a significant impact on the economy and power performance of the engine. At high speeds, the intake volume and efficiency can be increased by making full use of the intake inertia, so the valve opens early and closes later; at low speeds, the situation is just the opposite. At present, most modern engines use this technology.
3. For a piston four-stroke engine, the four strokes of intake, compression, power and exhaust are crucial. Among them, we pay special attention to the impact of the valve opening degree on the engine intake. The basic principle of cylinder intake is "negative pressure", that is, the difference in gas pressure inside and outside the cylinder. When the engine is running at low speed, in order to avoid the pressure balance inside and outside the cylinder, resulting in reduced negative pressure and insufficient intake, the opening degree of the valve needs to be precisely controlled, usually using a short stroke method; when running at high speed, in order to ensure that the engine can intake air smoothly, a larger valve lift is required.
4. In order to solve the challenges faced by engineers in balancing the torque characteristics of the engine at low speed and the power characteristics of the engine at high speed, variable valve timing technology came into being. This technology can flexibly adjust the valve lift according to the operating state of the engine, thereby ensuring high torque at low speed and high power output at high speed.