The lightweighting of automobiles has long been a new topic in the world. Passenger cars are the same, as are commercial vehicles. However, in China, due to the existence of overloaded reality, heavy-duty trucks have long been the main direction of development. Lightweight technology has long been neglected. With the strict implementation of the policy of restricting over-loading and weight-based charging, lightweight products have gradually become the focus of users and manufacturers. Before the user buys a car, he no longer asks "how many tons can be pulled", but "how many tons are heavier". However, the current understanding of weight reduction by heavy truck users and the promotion of lightweighting by heavy truck manufacturers are only to reduce the weight of vehicles and to pull cargoes in the event of a limited load. This is a misunderstanding. Lightweight design is not only to save materials, reduce self-weight, and increase the load quality; more importantly, it aims to reduce energy consumption, reduce emissions, improve operational efficiency, and drive safety.
To reduce the weight of vehicles, there are mainly the following measures:
1, using a variable cross-section leaf spring structure leaf spring
Because the leaf springs are all metal parts, the weight is very large, and the weight of the leaf springs is reduced, which is also an important measure for reducing the quality of the rigging. The variable cross-section leaf spring is composed of several leaf springs of variable cross-section in the longitudinal direction. Variable leaf springs not only reduce weight, but also improve ride comfort and service life by reducing friction between leaf springs. In addition, the use of rubber suspension or air suspension can also reduce the weight of the suspension system.
2, using a single frame frame beam
Compared with leaf springs, the weight of the frame is greater, and the weight of the frame is effectively reduced, which will greatly reduce the overall quality of the vehicle. With the improvement of design level, manufacturing process, and improvement of material properties, single-layer frames are fully qualified under standard load conditions. Due to the severe overloading of heavy trucks in China, it was almost unimaginable to use monolayers for heavy trucks before 2008. After 2008, domestic manufacturers began to launch their lightweight products one after another. The frame uses a single-layer beam structure.
3, use of composite materials
The cab is the assembly with the most composite materials, especially the outer cover: the front panel, angled panels, fenders, bumpers, and even the top cover, all using a large number of composite materials. On the one hand, this effectively reduces the weight of the entire vehicle. On the other hand, due to the good formability of the composite material, the molding structure can be more complex, more beautiful, and more accurate in size than the metal stamping. At present, domestic heavy trucks still prefer the cab structure of an all-steel structure, which is mainly related to the harsh working environment of heavy trucks in China: heavy trucks are faced with too many tests and injuries, and it is difficult to repair composite materials after they are damaged, which improves the maintenance of the entire vehicle. cost. However, from the perspective of new products introduced by heavy truck manufacturers in recent years, the proportion of composite materials used in vehicles is gradually increasing, and the use of a large amount of composite materials is an inevitable trend.
4, using aluminum alloy material
Aluminum alloys have a lower density than steel, so aluminum alloy materials, including sheet metal parts and castings, can be used where some composite materials cannot be replaced.
Aluminum alloy sheet metal parts are the most representative of the fuel tank, aluminum alloy tank material, not only reduce the weight, and the oil tank is not easy to rust, eliminating the trouble of regular cleaning. The body can also use aluminum alloy instead of cold rolled steel. In order to reduce its own weight, American heavy trucks use aluminum alloys to make cars. Due to the poor welding performance of aluminum alloys, they can only be riveted. Therefore, the US long heavy trucks we see are all rivets.
The rim, engine body, transmission body, etc., can also be cast aluminum alloys in a large amount, which can minimize the weight while ensuring sufficient strength and rigidity.
5. Use high-strength steel
In places where other materials cannot be replaced and only steel materials can be used, high-strength steel plates can be used to reduce the thickness of the steel plates and reduce the weight. High-strength steels can be used for cold-rolled steel sheets used to make bodywork and hot-rolled steel sheets for frame construction. In European and American heavy trucks, almost 100% of steel used in heavy trucks is high-strength steel. In the past, the proportion of high-strength steel plates used in domestic heavy trucks was relatively small, and they have been widely used in recent years. Even the cars of dump trucks have begun to use high-strength steel plates to improve the strength of the car and reduce its own weight.
6, use tailor welded plate
The cab is stamped and welded with steel plates. Due to the different structure and force conditions of different parts, different grades of sheet metal parts also use different grades of steel plates. The cab of a heavy truck may use dozens of different grades and grades. Thickness of the steel plate. However, with the development of CAE technology, through simulation experiments and analysis, it is possible to calculate the stress of different parts of the same sheet metal part. In order to reduce the unnecessary thickness of some parts, laser tailor-welding technology came into being. Laser welding technology is to combine two or more steel plates with different surface treatments, different steel types, and different thicknesses into one steel plate by laser welding. This kind of steel plate becomes a tailor welded plate. Tailor-welded panels are currently used in passenger cars, and the technology is very mature. Many of our familiar auto brands are widely used in their automotive products, but in commercial vehicles, especially the Volkswagen, GM, Ford, Toyota, and Honda. It is not used in heavy trucks. As the heavy truck is more sensitive to its own weight, the application prospect of the tailored welded plate on the heavy truck is extensive.
7, using castings
Due to limitations of materials and manufacturing processes, traditional parts of the punched and welded structure can only be of equal thickness. In order to ensure the overall strength and rigidity of the parts, the punched and welded parts are often heavy. The structural parts can be analyzed by CAE through finite element software to optimize the structure. According to the force conditions of each part, the complex variable thickness and variable cross-section structure are designed to maximize the reduction of unnecessary Local thickness, which greatly reduces the weight of parts.
8, using vacuum tires and ultra-wide tires
To reduce the weight of the vehicle, the tire can not be underestimated. The use of vacuum tires and extra-wide tires can also reduce the weight to some extent.
Compared with conventional tires, vacuum tires not only reduce the number of inner tires, but also reduce the structure of the rims. The entire vehicle is replaced with a vacuum tire, and the reduced weight is very objective. In addition, vacuum tires have a small resistance to travel and can reduce fuel consumption to some extent.
The driving wheels of heavy trucks generally use double tires. If they are replaced with ultra-wide single tires, not only can the number of tires be reduced, but the number of rims can also be reduced, and the weight loss effect is very significant. In addition, the ground area of ​​an ultra-wide single tire is not smaller than that of a double tire. Besides reducing its own weight, it can also improve running stability and avoid the phenomenon of “gesture†of the dual tires.
9, integration of parts functions, reduce the number of parts
In addition, integrating the functions of parts, integrating multiple parts and components, achieving multi-functional parts, reducing the number of parts, and making the structure more compact, it can also reduce the weight of the vehicle to some extent. Such as: the tank and the table pedal combination, the tank and SCR urea tank combination.
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