In the previous article, “Weight is equal to safety? After seeing these examples, I found myself hit by a face.” We have already shared with you the question of vehicle weight. Actually, with the demand for energy saving and emission reduction of automobiles More and more rigorous, lightweighting has become a very important consideration for brands when developing new vehicles. With the development of automobiles, the body size continues to increase, the safety factor continues to increase, the configuration becomes more and more abundant, and the structure becomes more and more complex. , but also to maintain a reasonable weight, is not simply a matter of a few pieces of iron can be completed. It can be said that lightweight means and effects, truly reflects the core technology gap between the R & D brands.
Before we talk about lightweighting, we first talk about what is the use of lightweighting.
Why WHY
Reduced fuel consumption
The most direct effect of lightweighting is fuel consumption reduction. According to currently recognized research results, the general automobile quality is reduced by 10%, fuel efficiency can be increased by 6% to 8%; every 100 kg of vehicle quality is reduced, 100 km Fuel consumption can be reduced by 0.3-0.5L. For increasingly stringent environmental protection requirements, and consumers are increasingly sensitive to fuel consumption, effectively reducing vehicle weight can significantly increase the competitiveness of the models.
Mileage increase
For electric vehicles, cruising range can be said to be lifeline-like. In general, the battery life of electric vehicles depends on the battery capacity on the vehicle body, and the battery capacity depends on the number of batteries. Therefore, the battery life is longer. Electric vehicles usually have more batteries and they are heavier. However, the heavier the vehicle body weight is, the greater the inertia of the vehicle is, the more energy the motor needs to provide for acceleration and braking, and the more serious the power consumption, the shorter the mileage of the electric vehicle. .
The body's lightweight and electric vehicle's life have a very close relationship.
In addition, with the increase of mileage, the fuel consumption of traditional fuel vehicles will gradually decrease, and the weight of vehicles will gradually decrease. However, electric vehicles will not lose weight as the power consumption decreases, and they will continue to push heavily when the power voltage drops. The body of the vehicle, the energy consumption situation will be further deteriorated. Therefore, to reduce the weight of the body, for the electric vehicle to enhance the cruising range has a very positive significance.
Increased comfort and handling
In general, the lower the mass of the body, the lower the inertia of the body and the more agile the maneuvers can be. In addition, the lighter body does not need to be supported by very stiff springs and suspensions, so a softer chassis can be used. Setting, shock absorption performance will be better, ride more comfortable.
How do HOW
Here, everyone knows the benefits of lightweighting. But lightweighting is not something that can be done simply by adding or subtracting materials. Today's cars are getting larger and larger, with more and more configurations, and safety requirements are increasing. The higher it is, the more difficult it is to achieve lightweighting under this precondition. However, many car companies are seeking some effective lightweight measures. Let's take a look at what they actually do.
Replace lightweight materials
At present, the production of automotive white-body materials is the use of low-carbon steel cold-rolled steel. Low-carbon steel is more cost-effective, but not rigid, and the density is also slightly larger, so many depots began to try to use a variety of materials to replace it. The first choice is high-strength steels (ie thermoformed steels). High-strength steels increase the rigidity of the material. As a result, the plates can be made thinner, and the use of less raw materials can naturally reduce the weight of the car. Of course, these high-strength steels are even stronger. High, but not tough enough, and the cost is higher, it is more suitable for some key parts to pay off the rigidity.
The Audi A8L uses aluminum as the main manufacturing material for the frame, but the thermoforming steel (purple section) is used for the structural strength. Since this material is a patented product and the price is very high, although the performance is excellent, only Will be used in key parts.
Another kind of material is aluminum alloy. Now many automakers are beginning to seek to use aluminum alloy instead of traditional low-carbon steel as the manufacturing material of the white body. For example, brands such as Mercedes-Benz, Jaguar, Audi, Honda, etc. have all launched aluminum. Bodywork. Relative to steel, aluminum alloys have better toughness, lower density, but less rigidity. So now more depots are also seeking to use high-strength steels and aluminum alloys as the main manufacturing materials for body-in-white to meet rigidity at the same time. , Energy absorption and light weight requirements.
The first generation of NSX was the first car in Japan to use an all-aluminum frame, while the second-generation NSX also adopted the design of an aluminum frame.
Jaguar, known for its athletic genes, also insists on the use of aluminum frame design.
The third kind of material is the use of various composite materials. Simply put, carbon fiber, plastics and other chemical materials are used. First of all, carbon fiber, not to mention those with annual output of only ten or twenty units of carbon fiber mono-shell super-run , talk about production models. The earliest use of carbon fiber to manufacture the entire frame should be BMWi3 and i8. And in the new generation of the 7 series, it also uses carbon fiber to make the roof beam structure and the B-pillar and C-pillar, the bottom side of the enclosure, Central channel and rear support.
BMW i8 and i3 test field for BMW Carbon Fiber Frame.
The Audi R8 uses an all-aluminium frame, but high-strength carbon fiber components (black parts) are used in the seat back, saddle and B-pillar sections.
In addition to BMW, the second-generation Audi R8 and fifth-generation A8 also use carbon fiber as one of the frame materials. Of course, there are many brands seeking to use carbon fiber wheels to reduce the unsprung mass impact on performance, including Ford. , General and other companies.
As the so-called (round a kilogram, 10 kilograms on wheels), reducing the unsprung mass has a huge leap in driving quality, so many high-end and performance brands have begun to study the use of carbon fiber rim products. The picture shows the use of GT350R Carbon fiber wheels, 40% lighter than the average size of the aluminum alloy wheels, provided by the Australian Carbon Revolution, single price of 20,000 euros.
Similarly, many brands are also studying the use of plastics to make the tailgate. However, the cost of manufacturing carbon fiber is relatively expensive, and how to effectively combine with other metal components is also a big problem.
Previously, LotusElan used glass fiber to make the body shell, and later Smart used plastic to make the body shell, which is a word 'light'.
Optimize the lightweight design of the body structure
Many brands are now developing new architectures and new platforms. In addition to increasing the general rate of platform components and reducing production costs between different models, the design of the platform can be optimized as much as possible. Lightweighting is also an important goal.
The Toyota TNGA new architecture, in addition to improving the general rate of platform components, lightweight design is also a focus.
The development of new platforms and new architectures can adopt a large number of modular integration designs. Different modules are used to optimize the structural topology to reduce unnecessary materials, reduce wall thickness, and reduce the number of parts, thereby achieving lightweight objectives. For example, Toyota's latest TNGA architecture, component design is more compact, the center of gravity down, improve the lightweight effect, maximize the core performance of the vehicle. At the same time use a large number of general-purpose parts, the initial general ratio of 20% to 30%, will eventually reach 70% to 80%.
Using advanced manufacturing process technology
The manufacturing process mentioned here does not exert the effect of light weight per se, but the manufacturing process is improved, and the materials and structures can achieve the best results, so that the above-mentioned lighter materials can be used, and the reinforcing components and material can be reduced. The amount used to achieve lightweight effect. For example, laser welding, roll forming to ensure the safety of the entire vehicle structure. Such as Cadillac on the use of original resistance welding process, BMW and other laser welding, etc., to achieve steel and aluminum welding.
Cadillac's innovative resistance welding process can achieve better aluminum alloy welding strength.
In addition, the use of high-strength steel thermoforming, high pressure forming and other ways to enhance the mechanical properties of the structure. Using structural adhesive bonding, material riveting and other technologies, you can achieve high-strength connections between the material components.
Jaguar's all-aluminum frame uses a large number of riveting and gluing techniques. In addition to providing connection strength comparable to that of welding, by optimizing the riveting position, it is also possible to reduce the amount of rivets by reducing the number of rivets and indirectly reduce the weight.
The new BMW 7 Series frame is reinforced with carbon fiber car roof beams and door frames. Different materials are connected using riveting methods.
All of these production processes are the basis for all light weight measures. For example, the all-aluminum frame used by Jaguar uses high-strength adhesives and rivets.
to sum up
It can be said that lightweighting has become an important factor for many vehicle manufacturers to open up the technological gap, and many self-owned brands with strong forward-looking attitudes have begun to invest a great deal of capital in lightening. BAIC New Energy has built a new energy source for BAIC. The Dresden Lightweight Technology Center develops and develops multi-material lightweight vehicles, key bodies of carbon fiber composite materials, chassis components, etc.; Geely Group has gradually approached Europe in the design of aluminum alloys, plastics, and lightweight structures. Mainstream level.
