What is the principle of BMW's variable valve lift?
2 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.
