1. Noise
vehicle noise, that is, when the cars on the road, the internal combustion engine, horn, tires, etc. will issue a large number of human beings do not like the sound. Serious car noise affect human health. In recent years, the city of motor vehicles increased rapidly, traffic noise pollution environmental phenomena accompanied by increasingly prominent. Experts believe that the greatest harm to the automotive environment is noise pollution. In fact, the city’s most clamorous noise should belong to the first row of car horns. Walking in the street, a steady stream of cars brought bursts of shrill horns, are the same whether you’re in the office, classroom, hospital, home, horn can not let your ears quiet.
Noise Source car body structure vibration excited by the path
①; air vibration
touchdown station ② wheel aroused;
③ body through turbulent atmosphere generated;
④ vibration and exhaust gas of the engine intake;
⑤ driveline vibrations excited mutual movement;
⑥ friction brake and the rim;
⑦ air-conditioning fan and the like.
1, engine noise: the engine of the vehicle is a source of noise, which noise generation is different as different engine speed (primarily through: front fender, hood, baffle wall, the exhaust pipe to produce and delivery).
2, road noise: road noise is high-speed driving when the wind cut into the form of noise and vibration generated by the travel drive chassis, as well as the impact of gravel road chassis will generate noise, which is the main road noise sources (primarily through: four doors, trunk, front fender, and front wheel arcing transfer).
3, tire noise: the vehicle tire noise at high speeds, the tire and the road surface friction generated, depending on the road condition determined larger size tire noise, tire noise worse road conditions, further mixed with asphalt dirt road tire noise appears very different (mainly by: four doors, trunk, front fender, and front wheel arcing transfer).
4, wind noise: wind noise means a vaporCar traveling at high speed during the oncoming wind pressure has exceeded seal drag into the car door is generated, the faster the traveling speed, the greater the wind noise (mainly by: four sealing gap, comprising the entire steel sheet produced and delivery).
5, resonance noise and other: a vehicle body itself is like a box, and the sound itself, and the overlapping nature of refraction, when the voice incoming vehicle, such as no sound absorbing and sound absorbing material and blocking, noise and will continue to refractometer overlap, resonance noise is formed (mainly through: into the car noise superimposed reflections).
car noise problem has two aspects: the car interior noise and external noise. The former affect the passengers in the car, which affect the exterior environment. Vehicle noise is the root of urban traffic noise, all countries attach great importance to the environmental protection department to develop a standard to allow the car noise, and improve the standard gradually modified over time, car noise standards of our code-named GB1496-79. Currently, high-speed traveling of vehicle exterior noise is mainly touchdown tire noise, vibration and vehicle noise is mainly noise boundary layer body structure.
significance Noise car
size
vehicle noise measure an important indicator of the level of quality of the car, so the car noise prevention is also an important topic in the world auto industry.
There are a variety of
car noise source, such as an engine, transmission, drive axle, shaft, compartments, windows, tires, relays, speakers, sound and so will generate noise. Some of these noises are produced by passive, active and some are occurring (e.g., artificial horn press). But the main source of only two aspects, one is the engine, the tires and the other is that they are passive occurred, as long as the car is running will produce noise.
In various engine noise, engine noise is the main surface of the radiation. Surface Noise combustion noise and the engine is made of two types of mechanical noise, combustion noise and mechanical vibration generated in the engine. Refers to combustion noise cylinder combustion pressure by way of the piston, connecting rod, crankshaft, such as a cylinder outward radiation noise generated, mechanical noise refers to the mechanical vibration noise between the movement of the piston, gears, and other mechanisms valve member from the impact. Generally, the combustion noise dominates at low speed, the mechanical noise dominates at high speed. The two are closely related, influence each other. practice shows that,Reduce vibration is a fundamental measure to reduce noise. Increase the stiffness and damping of the engine structure, a method of reducing vibration of the surface, which can reduce noise.
tire rolling noise generated in the road is great. The study showed that on a dry road, when the car reaches 100 km per hour, tire noise has become an important source of noise of vehicle noise. In wet road surface, even if the vehicle speed is low tire noise will mask other noise is the main noise source. Tire noise from the pumping effect and the tire vibrations. It refers to a so-called pumping effect, causing deformation of the tire when the tire is rolling at high speed, so that the air between the tire tread and the road surface light squeeze pressure, as the rolling of the tire is released, and the air from the contact surface of the tire, such continuous pressing release, the air burst out noise but noise faster the speed, the more severe the greater the vehicle noise. Tire vibrations and tire stiffness and damping related increase in stiffness (e.g., increasing the number of plies in the tire), the damping is reduced, the vibration of the tire will increase, noise also big. To reduce the noise of the tire tread can adopt a variety of patterns pitch, high damping rubber material, a good load balance adjustment of the tire to reduce the self-excited vibration.