Running stability of the hottest automobile engine

Running stability of automobile engine

how to choose the number of cylinders of automobile engine? Why are some brands of engines with the same number of cylinders very quiet, while some brands have obvious vibration

generally speaking, the more cylinders, the more stable the operation, and the higher the price of the engine. At that time, the polyether polyol unit with an annual output of about 15000 tons and the small paint raw material production unit will also be more expensive. In the past, for example, the revival plug internal combustion engine, the fuel burns in the cylinder, pushing the piston to do work, so that the car can overcome the resistance. If the engine wants to run continuously, it must have a cycle, which operates repeatedly according to the actions of suction, compression, work and exhaust. Among them, suction, compression and exhaust are power consuming. Generally, the piston of each cylinder of a four stroke engine goes back and forth four times, that is, the crank needs to rotate for two weeks to do work once. Therefore, it is difficult to work with only one cylinder. Just like when we step on bicycles, it's hard to step on one foot

anyone who has stepped on a bicycle knows that when the pedal moves from top to bottom, the foot can use up force, but when the pedal moves from bottom to top, the foot can't use up force. It depends on inertia to make the car move continuously. In fact, the most effective position for cycling is only about 90 degrees, as shown in the figure. Even though there is a large amount of polyurethane in the interior of two legged cars, some positions in the middle are still empty and rely on inertia to maintain movement. The same is true of engines. If the number of cylinders is relatively small, power discontinuities will occur, affecting the stability of operation

if two people step on a bike, the situation is different. The time of exerting force on the four feet can be evenly distributed at the interval of 90 degrees. The four 90 degrees are exactly one week, and the power will not be interrupted

one cylinder of a four stroke automobile engine works once, corresponding to two cycles of crank rotation, i.e. 720 degrees. Therefore, generally, the crankshaft phase angle of 4-cylinder engine is 180 degrees, that of 6-cylinder engine is 120 degrees, and that of 8-cylinder engine is 90 degrees. The more cylinders there are, the smaller the interval angle between the front and back work in turn, the less power interruption will occur, and the better the stability of operation

however, why are the operating conditions of engines with the same number of cylinders very different? Multi cylinder is an important condition for the smooth operation of the engine, but it is not the only condition. In fact, there are many reasons that affect the vibration of the engine, among which the inertia force is an important factor

the high-speed moving parts in the engine will produce a large inertial force, causing severe vibration of the engine. Although the dynamic balance method can be used to reduce the dynamic pressure caused by the inertia force on the bearing for the components rotating with a fixed axis, the internal torque will be generated due to the rotating inertia force when the number of cylinders is large and the crankshaft is long, which will bend the crankshaft and affect the running stability. Therefore, now the cylinders of high-speed engines with more than 6 cylinders are mostly arranged in a V-shape to shorten the length of the crankshaft

for components with non fixed axis rotation, such as the inertia force generated by the movement of the piston and connecting rod in the crank connecting rod mechanism cannot be balanced inside the component, and the existence of these inertia forces will cause the engine to shake. The balance of this type of inertia force is called "the balance of the mechanism on the base", which involves more complex technologies. In addition, for multi cylinder engines, the structural differences, the manufacturing dimension and processing errors of various parts and the uniformity of material density will affect the stability of the vehicle plastic frame interior weight reduction and low-carbon machine

the balance of inertia force is a key issue in engine design and manufacturing. Only through careful design and accurate testing means can the influence of inertia force be minimized. The difference of brands here is also that FRP bridges are reducing or even eliminating the protection needs, which is improving the attraction of composite materials. (end)