1, the dynamics of the car
The power of a car depends mainly on engine performance and driveline characteristics. It is usually measured in terms of maximum speed, acceleration time, and maximum climbing grade.
(1) Maximum speed: The maximum speed (km/h) that a car can achieve on a well-ground road (concrete or asphalt). The maximum speed of a typical truck is 80~110km/h. The maximum speed of up to 200km/h.
(2) Acceleration time: Acceleration time of the car is usually measured by the acceleration time of starting and passing acceleration. The short acceleration time means that the car's acceleration capability is good, and the average speed is high. The starting acceleration time in situ means that the car is powered by 1 The time required to reach a predetermined distance or vehicle speed after shifting to the highest gear with one or two speeds, and with the maximum acceleration strength. The number of seconds from 0 to 400 m generally indicates the acceleration capability of the vehicle's starting position. Acceleration time refers to the time required to accelerate to a certain high speed from the full speed of 30km/h with the highest gear or with the high gear.
(3) Maximum climbing grade: The maximum climbing grade of a car refers to the maximum climbing degree of a block on a good road when the car is fully loaded. The so-called slope refers to the ratio of the vertical height of the ramp to the horizontal length of the ramp. Percentage expresses. The maximum grade means the car's climbing ability. The maximum grade of the truck is 30%, which is about 16.5. The higher the maximum speed of the car, the shorter the acceleration time, the greater the maximum grade, the car The better the dynamic performance.
2. The fuel economy of the car
The fuel economy is usually used under certain operating conditions. The fuel consumption of a hundred kilometers of a car or a certain amount of fuel can be measured by the mileage of the car. China's fuel economy index is 100 kilometers of fuel consumption, which is 100 kilometers. The amount of oil is measured in units of L/100km, such as Santana 3000. The fuel consumption is 7.OL/100km. Some countries in the US, UK, etc. use mile/gal (mile/gal) for evaluation.
3. Braking of the car
The braking performance of a car is mainly related to the performance of the braking mechanism, the mechanical characteristics of the tire, the road conditions, the driving condition of the automobile, and the braking operation. The general needs are evaluated in the following ways.
Brake energy release. It refers to the ability of a car to rapidly reduce its speed until it stops. It is evaluated by braking distance at a certain initial speed, braking deceleration or braking. The braking distance is the most intuitive, and it has a direct effect on driving safety. Relationship, the driver can control the braking intensity according to the estimated parking distance. Therefore, the technical parameters of the braking system need to use the braking distance of the car to represent the system. The relevant functional departments usually also establish the safety according to the braking distance. Regulations. Braking deceleration and braking time are indispensable for analyzing and studying the braking process. In order to facilitate vehicle inspection, brake knives are also commonly used to evaluate the braking performance of vehicles. It is the most basic evaluation of braking performance. index.
The constantity of the braking performance refers to the thermal stability of the braking performance when the car is braked at a high speed and braked repeatedly for a short time and continuously under a long slope. The brake temperature rises during braking, and the friction coefficient decreases. , The braking capacity of the car is reduced. This phenomenon is called braking heat retreat.
Directional stability during braking. Normally refers to a motor knife that maintains straight running or a predetermined curve during braking. Braking is a vehicle with good stability. It can maintain straight running or pressing during braking. 1. Curved roads will not cause sideways slippage or loss of steering ability.
Brake deviation is the phenomenon of automatic or inward bias when the vehicle is driving in a straight line. This is mainly due to the fact that the braking force of the wheel (especially the steering wheel) is not equal to that caused by the brake. It is generally adjusted. , Maintenance can be eliminated. "Motor Vehicle Operational Safety Technical Conditions" stipulates: When using braking force to check the braking performance of the vehicle, the difference between the front axle left and right wheel braking force shall not exceed 5%; the difference between the rear axle left and right wheels shall not be greater than 8 %'. Its purpose is to prevent the occurrence of brake deviation.
4. Handling and stability of the car
The handling and stability of a vehicle depends on both the structural parameters of the vehicle and the many factors such as the driving environment and the road environment. If the stability is lost, it will cause the car to skid and tip over. The loss of control stability will cause the car to lose control. The same is the main performance of modern cars.
5. Car ride comfort
The smoothness of driving involves the statistical regularity of road irregularities, the vibration characteristics of the car suspension, seats, etc., and the human body's response to vibrations. The advantages and disadvantages of ride comfort will affect vehicle dynamics, handling stability and passability, as well as impact. The working reliability of auto bodies and the fatigue life of components are one of the main properties of automobiles. The evaluation index of ride comfort is usually evaluated after weighted calculation of vibration frequency and vibration acceleration.
6. Passability of cars
Assessing the parameters of the car's passing parameters, such as geometrical parameters and bearing and traction parameters, is also related to the structural factors of cars, convenience factors, and the real-life performance of the car. There is a minimum ground clearance for geometrical parameters. Approach angle, departure angle, longitudinal pass radius, transverse pass radius, minimum turning radius, etc.
