If car fans are still impressed, they should have a deep memory of the champagne glass tower on the hood when Lexus first launched the first high-end luxury model LS400 in the North American market thirty years ago. When entering the U.S. market in 1989, 15 goblets filled with water were stacked on the front hood of the Lexus LS400. The speed of the vehicle on the horsepower machine exceeded 200km/h, and the champagne tower stacked by the goblets did not move. The smoothness is amazing.
Recently, Toyota CEO Akio Toyoda reproduced the classic advertisement of the LS400 Champagne Tower thirty years ago, but the model has changed from the LS400 of that year to the new car LS500, and the V8 has become the V6, but the ending is not different. The extremely quiet cabin and engine room have always been Lexus's signature, so how did Lexus successfully give it? The more
cylinders, the smoother?
As we all know, the engine is often accompanied by vibration when it is running. The main reason is that when the engine is working, there are different vibrations in the four strokes of suction, compression, work, and exhaust. Only the work stroke is the combustion and expansion of the oil-gas mixture. The force generated and the direction of the force are different from the other three strokes.
When the engine does work, the piston and the crank structure connected to the piston move the most. The piston can be simply regarded as reciprocating up and down, while the crank is moving 360°. Among them, the forces and moments produced by the former are called first-order inertial force and first-order moment of inertia, while the latter are second-order inertial force and second-order moment of inertia. The force is simple and can be balanced, but the balance of torque is not easy. This is the cause of jitter when the engine is running.
If the engine has only one cylinder, this problem will be very obvious. To solve the problem of engine vibration, the easiest way is to add cylinders. For example, two cylinders can be fired at intervals. The offset can offset part of the first-order inertial force and the first-order moment of inertia, and the vibration of the engine during operation is also reduced. Small.
When the number of engine cylinders increases, the ignition interval can be smaller, and the forces generated by the reciprocating pistons can be offset by each other. Therefore, 4-cylinder, 6-cylinder, 8-cylinder and 12-cylinder engines are not only for the pursuit of power, but also for the pursuit of smoothness.
Unfortunately, the first-order moment of inertia is good for cancellation, but the second-order moment of inertia is not good for cancellation. When the piston reaches the top dead center, it will ignite and explode, and the piston will be pushed downward. The movement of the piston will drive the lower crank connecting rod mechanism and the lower part of the crankshaft. This will force the crank connecting rod and the crankshaft in one axial direction, which is also the second-order inertial force.
, to solve the second-order inertial force and the second-order moment of inertia, one is to use a balance shaft, and a balance shaft with a counterweight is placed under the crankshaft to generate a reverse vibration force to offset part of the vibration; the other is to use Multi-cylinder, try to place more, even-numbered cylinder structures on a crankshaft.
In theory, the more cylinders in a straight line, the more their vibrations will cancel each other out. This is more appropriate than adding a balance shaft. Therefore, BMW has always introduced straight-six engines because of straight-six engines to in-line engines. , The smoothest, much stronger than an inline four-cylinder engine.
The problem is that the vehicle’s engine compartment cannot fit a too long engine. Therefore, engines with V-cylinder arrangement were born, and the current mainstream V-type engines include V6, V8 and V12. V6 can be seen as a combination of two L3s; V8 is equivalent to connecting two L4s; not to mention V12, which is equivalent to two smooth L6 splicing.
returns to the Lexus LS500, which is equipped with a V6 engine. Needless to say, the ride comfort, not to mention this car adopts many new technologies for ride comfort and comfort.
engine mount technology
wants to reduce vibration, not only from the vibration source, that is, the engine itself, but also from the vibration propagation path. And luxury models like Lexus LS500 will use advanced engine mounting technology. Engine mounting technology also refers to connecting the support block between the engine and the frame.
Generally speaking, the main function of engine mountIt must support the engine, limit the displacement of the engine and important vibration isolation. After all, if the engine and the body adopt a rigid connection point such as bolts, under the influence of the continuous acceleration and deceleration of the vehicle and the vibration of the engine itself, it is easy to tear the connection point and make the vehicle lose power.
is hard but soft. Since the vibration is large, add some rubber. Thus, the rubber engine mount suitable for today was born. The rubber engine mount can effectively absorb the vibration generated by the engine and convert it into heat consumption. In this way, not only the connection between the engine and the body becomes more reliable, but the vibration of the engine does not affect the body.
Unfortunately, rubber due to its aging nature, the ability to dampen vibration is not static, so more advanced hydraulic engine mounts were born. Hydraulic mounts have more advantages than rubber mounts. By using hydraulic damping to increase the stiffness and damping at low frequencies, the jitter of the engine is improved.
The hydraulic mount can only passively improve the engine vibration, so there are semi-active mounts and active mounts. Some Lexus models use active engine mounts, which can actively generate force through sensors and actuators, and actively offset engine vibration.
Obviously, the active engine mount is more advanced and can deal with the complex vibration caused by different road conditions, so only some high-end models will adopt this configuration.
Although the Lexus LS500 is a front-rear drive, it is more stable than the front engine compartment that is not involved in the "driving", but this does not prevent the challenge of the Lexus LS500 champagne tower reflecting the car's excellent performance on NVH, and also It demonstrates the continuity and smoothness of this car in terms of power output. All in all, if you want to complete the Champagne Tower challenge, you need to consider many aspects such as engine and suspension. Of course, the most important thing is to find someone with steady hands to set up the champagne tower.
