From the brake system to see the new energy vehicle "oil to electricity" advanced

Posted 2020-04-30 08:50:30 +0000 UTC

With the rapid popularization of new energy vehicles, the performance of automobile brake directly affects the power recovery performance of the vehicle at work, and determines the endurance of the vehicle, so it becomes an important focus of the development of new energy vehicles. In order to let you better understand the principle behind the brake, today, the author will carry out a detailed analysis around "brake energy recovery". The braking system of traditional fuel vehicles is not suitable for pure electric vehicles. First of all, before understanding the braking energy recovery system of new energy vehicles, let's understand the braking principle of traditional fuel vehicles. It is mainly composed of brake master cylinder, vacuum booster, brake disc and other parts. Its working principle adopts "friction braking", that is, great friction is generated in the braking process, and the kinetic energy of the vehicle is converted into heat energy consumption, so as to achieve the purpose of reducing speed. However, a large amount of energy generated by this process can not be recovered, resulting in an increase in fuel consumption. Compared with the traditional fuel vehicles, the brake system has not only friction braking, but also a unique brake energy recovery system, which can effectively recycle the energy wasted in the friction braking of fuel vehicles. The principle can help the vehicle slide / brake, the kinetic energy generated on the wheel is transmitted to the motor through the transmission system, the motor works in the way of power generation, and charges the power battery, so as to realize the energy recycling, guarantee the vehicle to reduce energy consumption, and then extend the endurance mileage. At the same time, the brake torque of the motor can be applied to the driving wheel through the transmission system to achieve deceleration and parking. In the current new energy market, although most of the braking systems of the products are also equipped with corresponding energy recovery systems, they are basically based on the existing structure of the traditional fuel vehicle, and are technically improved. They are generally divided into service braking system, parking braking system and auxiliary braking system. As shown in the figure below, they keep the original vacuum booster and relevant pipelines of the fuel vehicle, and then connect the other end with the electronic vacuum booster pump. When the sensor detects that the vacuum degree of the booster is insufficient, the electronic vacuum pump starts to work and maintain the vacuum environment. In this way, they ensure that the vacuum booster can provide assistance for the driver as before. Like the popular pure electric vehicle on the market, the braking system of geometry a and aion s adopts the above similar processing methods, and the vehicle is braked through the configuration of ESC, vacuum pump and vacuum booster. However, the defect of the scheme is that the working stability of the electronic vacuum pump is insufficient, the brake failure is easy to occur, and the service life is short. More importantly, like the vacuum booster in the fuel vehicle braking system, it will lead to energy waste when the vehicle brakes and decelerates, which will affect the energy recovery efficiency, and can not effectively extend the range. The braking energy recovery system adopted by aion s and geometry a, which is more intelligent, will become a "must" for high-quality pure electric products. The author believes that the braking energy recovery system, based on the existing structure of traditional fuel vehicles and technical improvement, is only for cost saving, not the best solution to the braking problem of new energy vehicles. If a booster device is designed between the brake pedal and the brake master cylinder to replace the traditional vacuum booster, it can eliminate the dependence of the brake system on vacuum completely. Among the major international accessory manufacturers, the third generation IEB system of Mobis, the IPB intelligent integrated braking system of Bosch and the integrated dynamic braking (IDB) module of Wandu are the leading intelligent braking system configurations in the industry. Among them, the new energy leader in the Chinese brand camp will carry the Bosch IPB intelligent integrated braking system for the first time for its future flagship model, BYD Han. In the joint venture brand camp, Beijing Hyundai, which has the status of "leader in new energy field of joint venture", has provided its first pure electric car, festa, and the first pure electric SUV, oncino pure electric, with the third generation IEB system of modern Mobis, which helps the vehicle bring more real endurance performance. Compared with geometry a and aion s of the same level, it has a great advantage. Specifically, the third generation IEB system equipped with festa pure electric has the advantages of high integration, lightweight and fast response compared with the traditional brake system of pure electric products. Among them, the weight is reduced by 3.1kg; the parts are reduced from 3 to 1; the reaction time of hydraulic pipeline is greatly reduced from 0.37s to 0.24s Behind this series of figures, the model has greatly improved the energy recovery efficiency and laid a solid foundation for extending the endurance. (the third generation IEB system is equipped for festa pure electric / oncino pure electric) (the brake system adopted by aion s and geometry a) at the same time, the system allows the driver to step on the brake pedal, not to transmit "force", but to transmit electrical signals to the intelligent booster. According to the state of the driver's operation of the brake pedal, it intelligently detects the change of the stroke position when the pedal is depressed, so as to determine the total demand of the brake force at the wheel end. Combined with the current power battery power, vehicle speed and energy recovery level, it intelligently distributes the hydraulic pressing force and regenerative braking force, so as to convert the energy generated by sliding into electric energy and store it again. How to apply the energy recovery system to the vehicle models, each family shows its own way. The most representative is the design of the energy recovery paddle used by the pure electric power of festa. The paddle is located under the steering wheel, and the recovery level is set to 0, 1, 2 and 3. The driver can easily recover the energy by "left plus right minus". If the road conditions permit, the driver can pull the left paddle and keep it still, which can also help the vehicle to achieve a slow stop at a certain distance. The whole process is efficient and convenient, and will not cause any trouble to the driver on the way. In contrast, geometry a adopts the three-level energy recovery settings of "weak, medium and strong", and the driver needs to adjust through the virtual touch button on the central control. In my opinion, this function is not as rich as the pure electric power of festa, and it is not as user-friendly as the pure electric power of festa in operation experience. In the last moment, the development of new energy vehicles in China is faster and faster, and pure electric vehicles begin to enter thousands of households. Electric vehicles will become an important means of transportation for our travel in the next decade or even longer. But we need to keep sober. The brake energy recovery system, which is based on the existing structure of the traditional fuel vehicle, has not been able to solve the problem of more energy waste in the actual driving process of the vehicle, and the intelligent and electronic brake system is the trend of the development of pure electric products. For example, the festa pure electric system mentioned in the article, whether it is the third generation IEB system or the function of energy recovery paddle, has carried out efficient deduction of energy recovery, and has also pushed the "fast forward" key for the technical innovation of pure electric energy recovery. This is worth learning from other competitors.

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