Understand electric vehicle chassis construction

Chassis system includes suspension, braking, steering and other subsystems. In the traditional sense, it affects the comfort, safety and handling of the vehicle, and for new energy vehicles, its influence is more profound.

The chassis system of new energy vehicles needs to adapt to the diversity of on-board energy, suitable for highly integrated system modules, while not limiting the design of the interior space and external modeling of the car.

General requirements for new materials, new processes and stability of chassis parts

Lightweight and new materials

One of the development directions of automobile chassis in the future is lightweight, and the demand for light alloy materials and high strength steel will increase greatly in the future. Chassis for the use of aluminum alloy will be more and more; The demand for magnesium alloys is also increasing. However, it is also necessary to continuously study some new designs to meet the needs of light weight of auto parts.

stability

The stability of chassis parts is the basis of automobile safety. To achieve the performance of strength, flexibility, fatigue resistance and damage resistance, the application of automobile frame and axle for pipe hydroforming technology will be more and more frequent. The pressure processing technology is developing towards high efficiency, automatic reduction of automobile weight and cost.

casting

Chassis castings are developing to high performance, thin wall, light weight, precise (accurate) size and excellent machinability. Casting production process to clean, waste recycling, high efficiency, energy saving, material saving, environmental protection of green casting direction.

machining

The mechanical cutting technology of chassis parts has abandoned the traditional mode and developed into the survival mode of production line characterized by flexible technology. High efficiency, precision, flexibility and automation are the main trends of machining technology change. High-speed processing technology, agile manufacturing technology, intelligent processing technology, green processing technology, etc., will be rapidly developed.

Surface treatment

The protective electroplating of automobile parts has been developed from the original single galvanized passivation process to the zinc alloy coating with better corrosion resistance, heat resistance, low hydrogen brittleness, good workability and environmental protection properties and chromium-free dallol process. While the corrosion resistance of the coating is greatly improved, the direction of good heat resistance and low friction coefficient of the coating is developed.

Environmental protection requirements

In the field of chassis, with the continuous improvement of environmental protection requirements, at present, the world's major automobile companies are focusing on the development of environmentally friendly parts, such as low rolling resistance tires, green tires, wheel balance block without lead, no chromium six new parts coating technology, electric steering system, believe that in the near future, chassis technology will be more and more broad in the direction of environmental protection.

Modern automobile chassis is electronic

With the application of various automotive electronic auxiliary functions in chassis, the active safety and driving comfort of vehicles have been significantly improved. These systems include ABS/ASR/ESP integrated control system, Adaptive Cruise control system (ACC), Parking Assist system (PLA), lane departure and driver warning system, tire pressure monitoring system (TPMS), and adjustable damping control system (ADC). With the chassis electronic control system to more and more electronic, intelligent, network direction development. 

Chassis design requirements

 

The key consideration of chassis design is to meet the performance indicators of the vehicle. Automobile should have the basic performance can be summarized as power, economy, braking, stability, ride comfort, safety and durability. Generally speaking, chassis engineering includes front and rear suspension, steering system, brake system and wheel design configuration. The performance of the vehicle directly related to these systems are braking, operating stability and ride comfort. The suspension components of the chassis should be firm enough, and whether the design is in place directly affects the force of the body of the frame, and the chassis design is also related to the durability.

Chassis design requirements

 

 

         

        

New energy vehicle chassis design characteristics

 

The chassis design of new energy vehicles is very different from that of traditional fuel vehicles. First of all, the body design has greater freedom. Now the chassis is more and more flat. For good air mobility, the bottom is generally flat. The body is separated from it, so the design freedom of the body becomes greater. Second, the interior space is increased. Now with integrated design concepts, including electrified ESPs, electrified designs are becoming higher and higher, reducing the number of components and thereby reducing the space on the chassis to free up internal space. Third, due to the higher degree of systematic design, fewer and fewer products, production, maintenance is also greatly simplified. Fourth, the battery pack is now fixed at the bottom of the chassis, and the weight and axis are very low, which also increases the maneuverability of the vehicle.

Three aspects should be considered in the chassis design of new energy vehicles

First, the application of vehicle chassis design platform, that is, in chassis design, including chassis design of the framework, as well as its sub-systems need to remain unchanged. Secondly, the subsystem of automobile chassis should be improved appropriately according to the original frame. For the design of the chassis, it is necessary not only to install the vacuum power pump, but also to adjust the frame properly to improve the vacuum source. Of course, also change the new powertrain reducer interface. On the basis of the completion of the parts design, CAE analysis method should be used for the suspension system to reduce the noise. Thirdly, the layout of the rear cabin of the car body will change with the new design scheme adopted by the subsystem. After a series of detailed accounting of the load and the quality of the car, the safety factor of the suspension system is guaranteed. Otherwise, it is necessary to reset the sub-system. At this time, it is necessary to adjust the task of the suspension system. Analyzing the distribution of the front axle load and the rear axle load of the new energy vehicle, it will be found that the parameters of the suspension system should be redesigned. Determine the suspension four-wheel positioning parameters, using Adams analysis to determine, but it is best to ensure that the original design scheme, combined with the actual, so as to effectively save the development cycle, reduce the cost of development.

New energy vehicles maintain the load-bearing body

New energy vehicles to maintain the bearing type of body, is that many cars will use this design. Since the subframe can not bear the relevant functions of the body mass, it is necessary to determine the mounting point in the design of the powertrain components. In the suspension design of the body, to conduct quantitative analysis of the body, CAE analysis method can be adopted, which can avoid the overall layout difficulties caused by the non-standard suspension design space to a certain extent. Since the chassis can form a relatively large frame, the bearing capacity of the chassis is enhanced, in which all the power systems can be laid. Therefore, in the early stage of the design of new energy vehicles, it is necessary to plan the components, which can not only improve the simplicity of the overall layout, but also reduce the overall quality of the body with the reduction of the center of gravity.

Electronic control braking

Automobile braking system is a series of special devices that apply certain pressure to a certain part of the automobile, mainly the wheel, so as to force it to brake. The main thing is to stay safe and change the speed of the car. Unlike traditional automotive braking systems, electric vehicles cannot use the motor as a vacuum source, so the power of braking is naturally a difficulty. Today's more widespread solution is to use a vacuum booster as a booster actuator, and an electric vacuum pump as a vacuum power source, but this also has some drawbacks. As a result, a new source of power -- electricity -- has been adopted. Bosch, a well-known auto parts supplier, has released an electro-mechanical booster called the iBooster. The invention of auto parts has brought many new functions that can be intelligent. It uses electronic technology to realize braking through electronic control. Its response time is also three times faster than conventional car braking systems.

Steering mode selection

The steering system of a conventional fuel vehicle requires the engine to drive, which provides hydraulic power. But now fuel cars are also electric power steering, or EPS, EPS is very important for electric vehicles. Using EPS with ECU controller, active control can be achieved, that is, the driver does not control the steering wheel, let the car automatically turn. You can do things like automatic parking, which is innovative. Steering wheel is an important part of driving a car and an important tool for perceiving road conditions when driving a car. Different drivers may have different requirements for the steering wheel, but generally they want to be light and not light, that is, they can transmit some sense of the road. This feature really adds to the car's personalized options.

Highly controlled suspension

When it comes to uneven roads, drivers may have hoped that the chassis of their car would adjust to the level of the road. For electric cars, the water involvement of electric motors is better than that of conventional engines. In the modification market, there are already pneumatic suspension that can achieve active control of the lift. It is mainly through the electric control air pump to air bag shock absorbent inflating or deflating, to achieve the rise and fall of suspension height. But this method will destroy the original car interior styling and interior trim. On the basis of intelligent large screen, and then configure a set of electronic pneumatic suspension, in fact, you can realize the adjustment of suspension height.