What is the principle of BMW's variable valve lift?
4 Answers
At different engine speeds, the requirements for valve lift vary significantly. At low speeds, due to the small intake air volume, if the valve lift is too large, it will not be able to generate sufficient intake vacuum. After the fuel injector sprays fuel, it cannot fully mix with the inhaled air, resulting in low combustion efficiency, a significant reduction in low-speed torque, and increased emissions. Here is additional information: Roller-type valve tappets The contact surface between the roller-type valve tappet and the intermediate push rod is a sloping platform, where rolling friction occurs to reduce mechanical losses. Additionally, the tappets and push rods are divided into different grades, and components of the same grade are always installed on the same cylinder.
BMW's variable valve lift, known as Valvetronic, is essentially a smart design in BMW engines. It uses a small electric motor to adjust the height of the valve lift, unlike traditional engines that rely solely on the throttle to control air intake. This allows the valves to vary like a dimmer switch, giving the engine more freedom in air intake, reducing energy loss, and providing smoother acceleration. When driving, you'll notice quicker response and better fuel efficiency. I've studied this system—the principle involves the motor altering the camshaft's amplitude through a lever mechanism. When the valves open wider, more air enters; when they open less, air intake is reduced, achieving stepless adjustment. This design is common in BMW's N-series engines, enhancing overall efficiency. Remember, it makes the engine quieter and more efficient at low speeds while delivering strong performance at high speeds—a true piece of cutting-edge tech.
As a BMW owner, my experience with variable valve lift is quite intuitive. The acceleration is crisp when driving, with an immediate push-back feeling when stepping on the gas, making overtaking incredibly satisfying. It's also fuel-efficient, typically staying under 8 liters per 100 km on the highway. Technically, it optimizes airflow by adjusting valve opening, reducing the workload on the throttle. Having driven BMWs for ten years, I find this system reliable with few issues. Regular maintenance, like oil changes and keeping an eye on small sensors, is key. Overall, this technology enhances both driving pleasure and fuel economy, making daily use hassle-free.
Variable valve lift is a core technology in BMW engines, directly controlling the valve opening height. Simply put, it uses an electric motor to adjust in real-time, allowing the valves to open wider or narrower as needed. This design originated from the early 2000s BMW 7 Series, aiming to make the engine more efficient and fuel-saving. Compared to fixed valve systems, it precisely regulates air intake and reduces idle waste. The most notable highlight is the smooth acceleration when driving. The principle isn't complex, but its implementation is highly precise, ensuring reliability.
