When the car body designer gets the task of product design, the outline dimensions (length, width and height) in the detail table are indispensable, but there are also several important parameters, which are also very important or even indispensable for the vehicle designer. .
Among these important parameters, the most important is the "ground clearance". According to the definition, the ground clearance refers to the vehicle support plane (X plane) and the middle area on the vehicle (parallel to the Y plane and the part contained between two planes that are equidistant from each other. The distance between the two planes is on the same axis. 80% of the minimum distance between the inner edges of the wheels at both ends), this definition explanation may be confusing and incomprehensible to readers who do not have the concept of geometric coordinates.
In fact, it's very simple. You can see from the illustration that the orange area shown in the figure is the ground clearance area, to the effect that it refers to the distance between the ground and the rigid object at the bottom of the vehicle.WhilecarThe "minimum ground clearance" in the parameter table refers to the distance between the ground in the orange area and the lowest point of the rigid object at the bottom of the vehicle. In other words, the minimum ground clearance reflects the ability of the car to pass obstacles or uneven ground without collision. Don't underestimate the minimum ground clearance. Its fixed value is reasonable and unreasonable, which directly affects the vehicle's passability and appearance coordination. The minimum ground clearance should take into account the passability of the unloading platform during the transportation and the possibility that the car will not collide when it is close to the edge of the general sidewalk. If sales are restricted to a certain country or region, the local road quality should also be considered. At the same time, the value of the minimum ground clearance is limited, which is related to the function of the model and aerodynamics. For example, the minimum ground clearance of a sports car will be relatively small, while the minimum ground clearance of an SUV will be relatively large. If you arbitrarily increase or decrease the minimum ground clearance regardless of the type of vehicle, the performance of the car will be affected, and the appearance of the whole car will appear uncoordinated and look awkward.
Since the ground clearance of a car is the distance between the ground and the rigid object of the vehicle chassis, that is, it contains the contour line of the lower part of the car body, so it is also related to the car's approach angle, departure angle, longitudinal passing angle, floor height and other parameters. . Some cars emphasize these parameters in the introduction of technical performance. For example, cars with off-road performance such as SUVs require higher passing ability, so the approach angle, departure angle, etc. must be indicated; as a car, approach angle and departure angle are required. The angle is more reflected in the appearance of appreciation.
The approach angle refers to the horizontal plane (ground) and the front wheel when the vehicle is statically loaded.TiresThe maximum included angle between the planes of the outer edges, and any parts fixed to the vehicle in front of the front axle must not be below this plane (see illustration mark 1).
Departure angle refers to the horizontal plane (ground) and the cut to the rear wheel when the vehicle is statically loadedTiresThe maximum included angle between the planes of the outer edges, and any parts fixed to the vehicle behind the rear axle must not be below this plane (see illustration mark 3).
Longitudinal passing angle refers to the smallest acute angle between the horizontal plane (ground) and the two planes that cut the outer edges of the front and rear tires when the vehicle is under static load (see illustration mark 2).
Floor height refers to the vertical distance from the car body floor to the ground when the vehicle is under static load.
Make sure that the ground clearance also includesFuel tankThe height, the lowest contour line of the engine, etc., can be said to involve many aspects of the body design, which is the key to "move everything".
The height value of the ground clearance of the car is not static, it depends on the load condition. Therefore, the determination of the ground clearance also depends on the change of the load, and the ground clearance should be considered according to the maximum value of the load change. Therefore, the weight concept of the car is also involved here. The load condition of the car is divided into two situations, one is the empty weight, which includes the equipment on the car and the standard tools on the car. The other is the design weight, which refers to the sum of the empty weight and the load on the seat, that is, the weight of the car when it is loaded. The design is set according to relevant standards. According to the German and Chinese standards, the weight of each passenger in the car is set to 68 kg, plus each person is set to put 7 kg of luggage in the trunk. For example, Shanghai POLO 1.4L sedan, with 5 passengers, its technical parameters indicate automatic transmission vehicle's curb weight (net weight) 1140 kg, full load weight 1515 kg; manual transmission vehicle's curb weight (net weight) 1,100 kg, full load weight 1475 kg. All are formulated in accordance with Sino-German standards.
It can be seen from the above that some parameters on the car are very critical, and they often involve other aspects, such as ground clearance, front and rear axle mass (weight), wheelbase, etc., which basically constitute the overall layout of the car. As long as these values are compared, the type and variety of the car can be judged.
Explanation: "Weight" should be "quality" as a formal term in automotive engineering. This website is for the sake of popularization, and at the same time, it avoids confusing people's usual "quality". Therefore, in the "Technical Talk" and "Car" column introduction performance tables of this website, "weight" is written instead of "quality".
Che Huitong
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