First of all, before the official results of the investigation are available, our following analysis is based on existing materials and some judgments given by industry insiders.
Recently, the Xiaomi SU7 track hit the hot list for the first time.
It is reported that the accident occurred on the Tianma Track, and after the party drove the Xiaomi SU7 Max for five laps, the brake pads were worn out, resulting in the inability to brake effectively in the last corner, and finally the vehicle rushed off the track and crashed into the guardrail. Fortunately, the driver adjusted the impact point in time after the vehicle lost control, and chose the tire wall as the impact object, reducing the impact force. Despite this, the impact still triggered the deployment of the front airbags, but the driver was not injured, which reflects the good performance of the Xiaomi SU7 in terms of safety.
The person mentioned in the video that he needed to apply the brakes about seven times during a lap of the track, for a total of 40 brakes, which led to rapid wear and tear of the brake pads. The speed of the accident was 174 km/h, but the impact speed was reduced to about 55 km/h due to the single-piston braking system at the rear wheels, the vehicle's kinetic energy recovery system and the cushioning of the sand. The party stressed that the Xiaomi SU7 Max was not a racing design, and the design of the brake pads was not defective, but the use in extreme conditions such as the track led to wear and tear.
Relevant information shows that Xiaomi SU7 uses Bosch DPB2.0 intelligent decoupling braking system (Decoupled Power Brake) + ESP10.0, which is a set of fully decoupled brake-by-wire scheme. In this system, the brake pedal and the braking system are not mechanically coupled, but are controlled by an electronic control system. If a node in the electronic control system fails, it can cause the brake pedal to lose its braking effect, even if the brake pedal still feels normal.
Whether there is an electronic control node failure in the video, it is not clear, but the blogger reported in the video that there was feedback when the brake pedal was pressed, but it could not be braked, which is also a disadvantage of the intelligent decoupling braking system.
However, the intelligent decoupled braking system also has many advantages, especially in the field of new energy vehicles and autonomous driving.
First of all, the intelligent decoupling braking system can effectively recover braking energy and convert it into electrical energy for storage, thereby improving the energy efficiency of the vehicle and greatly improving the range of the model, which is especially important for electric and hybrid vehicles, because it helps to extend the range of the battery. This is followed by a more precise and fast braking response, which enables shorter braking distances and better vehicle stability in the event of an emergency. Third, it can reduce the noise and vibration in the braking process, electric vehicles are not better than fuel vehicles, without the engine, any abnormal noise will have clear feedback, so the intelligent decoupling braking system can provide a more comfortable driving experience. The fourth is to help reduce the weight of the vehicle and save space.
To sum up, the intelligent decoupling braking system provides an advanced braking solution for Hyundai through its efficient energy recovery, excellent safety performance, good driving experience and high adaptability to future technology, which is widely used by a large number of car companies, such as domestic car companies Zeekr 001, NIO ES6, GAC Aion LX and other models.
For this accident, some professionals have analyzed that Xiaomi SU7 uses NAO material brake pads, which is a better choice in ordinary civilian vehicles, and can provide good braking performance and comfortable driving experience. However, in extreme track conditions, such brake pads may not be able to withstand sustained heavy use. Although the Xiaomi SU7 has an achievement of 3 seconds and 000 acceleration in the actual test, it is not suitable for running on the track.
On the track, due to the high speed of the vehicle and frequent sudden braking, the braking system generates a lot of heat due to friction, causing the temperature of the brake pads and brake discs to rise sharply. When the temperature exceeds a certain threshold, the coefficient of friction of the brake pads decreases, a phenomenon known as brake thermal attenuation. In this case, the wear of the brake pads can accelerate, and even a fire may occur. Some bloggers observed that the brake pad caught fire when conducting 22 consecutive extreme tests of 100 kilometers of full braking, but the braking distance did not increase significantly, indicating that the braking system of Xiaomi SU7 has large design redundancy in daily use.
The brake pads used in racing cars are significantly different from those used in regular passenger cars in terms of material, design and performance. Racing brake pads need to maintain high performance under extreme conditions, such as high speeds, high temperatures and continuous braking, which place higher demands on the material and construction of the brake pads.
Racing brake pads are typically made of high-performance friction materials, such as carbon-ceramic composites, resin composites of steel and aramid fibers, etc. These materials are able to provide a high coefficient of friction while having good heat and wear resistance. For example, the brake pads of an F1 car are capable of working at temperatures of more than 1,000 degrees Celsius, while the brake pads of an average passenger car generally operate at a temperature of around 100 degrees. In addition, the brake discs of F1 cars have a large number of air vents and non-powered cold air devices to help cool the brake pads and discs. In addition, racing brake pads have a high coefficient of friction and are able to provide strong braking power in the event of emergency braking.
Xiaomi SU7 is not equipped with special brake pads for racing, and the body design does not design a large number of vents and cooling devices for tires and brake pads, so there will definitely be problems with running on the track for a long time.
Xiaomi's official suggestion is that for the most severe and extreme track conditions, the vehicle needs to be reconditioned, and it is not appropriate to use the original configuration directly on the track.