01
Safety first, comfort second
Car seats mainly include many different types of parts such as frames, electrical structures, and foam covers. Among them, the seat frame is the most important component in car seat safety. It is like a human skeleton, carrying seat foam, cover, electrical parts, plastic parts and other parts that are similar to "flesh and blood". It is also the core part that bears load, transmits torque and increases stability.
The LIL car series seats use the same platform frame as BBA, a mainstream luxury car, and Volvo, a brand known for its safety, laying a good foundation for seat safety. The performance of these skeletons is relatively better, but of course the cost is also high. The LI car seat R&D team believes that it is worth paying a higher cost to better ensure the safety of the seat. We also need to provide reassuring protection for our occupants even where we can’t see it.
"Although every OEM is now improving the comfort of seats, and LI has done an excellent job in this regard, we have always been aware that there is a certain natural contradiction between safety and comfort, and we require all The design must be based on safety, and then consider comfort,” Zhixing said.
He took the anti-submarine structure of the seat as an example. As the name suggests, the function of the anti-submarine structure is to reduce the risk of the seat belt sliding from the pelvic area into the abdomen of the occupant when a collision occurs, causing squeezing damage to the internal organs. This is particularly useful for women and smaller crew members, who are more likely to dive due to their small size and weight.
In other words, "When a vehicle encounters a collision, the human body will move forward on the seat due to inertia and sink downward at the same time. At this time, if there is an anti-submarine beam in the seat to hold the buttocks, it can prevent the buttocks from moving too much "
Zhixing mentioned, “We know that some Japanese cars will place the second-row anti-submarine beams very low, so that the foam can be made very thick and the ride will be very comfortable, but safety must be compromised. And Although the LI product also focuses on comfort, it will not compromise on safety. "
First of all, we fully considered the energy generated when the entire vehicle collided, and selected large-sized EPP (Expanded polypropylene, a new type of foam plastic with excellent performance) as a support. We repeatedly adjusted the EPP in multiple rounds during the later verification. The layout position, hardness, and density are required to meet the crash test performance requirements. Then, we combined the comfort of the seat to finally complete the shape design and structural design, ensuring safety while providing comfort.
After many users buy a new car, they add various decorative and protective items to their car, especially seat covers to protect the seats from wear and stains. Zhixing would like to remind more users that while seat covers bring convenience, they may also bring certain safety risks. "Although the seat cover is soft, it destroys the structural form of the seat, which may cause the direction and magnitude of the force on the occupants to change when the vehicle encounters a collision, increasing the risk of injury. The greater hazard is that the seat Seat covers will affect the deployment of airbags, so it is recommended not to use seat covers.”
Li Auto's seats have been fully verified for wear resistance through import and export, and there is absolutely no problem with wear resistance. "The comfort of seat covers is generally not as good as genuine leather, and the stain resistance is less important than safety." Shitu, the person in charge of seat technology, said that as a professional R&D worker of seats, he uses his own car Seat covers will not be used.
In addition to passing the safety and performance verification within the regulations with high scores, we will also consider more special working conditions encountered by users in actual use, such as the situation where there are three people in the second row. "We will use two 95th percentile fake A person (95% of the people in the crowd are smaller than this size) and an 05 dummy (female dummy) simulate a scene in which two tall men and a woman (child) sit in the back row. The greater the mass, the more likely they are to sit opposite each other. The requirements for chair strength are even more stringent.”
"For another example, if the rear backrest is folded down, and the suitcase will fall directly onto the front seat back when the vehicle collides, is the strength of the seat strong enough to support the seat without being damaged or causing any major damage? displacement, thus endangering the safety of the driver and co-pilot. This needs to be verified by the trunk collision test. The current national standards and American standards do not mandate that the front seats undergo this test. Only we and those who pay more attention to safety. Car companies such as Volvo will have this kind of self-requirement.”
02
Flagship-level products must provide flagship-level security
American scientists studied hundreds of car accidents that resulted in the death of drivers and found that without wearing seat belts, it only takes 0.7 seconds for a car traveling at 88 kilometers per hour to crash and kill the driver.
Seat belts are a lifeline. It has become common knowledge that driving without seat belts is dangerous and illegal, but rear seat belts are still often ignored. In a report in 2020, a Hangzhou high-speed traffic police captain said that from the investigation and prosecution, the rate of rear-seat passengers wearing seat belts was less than 30%. Many rear seat passengers said they never knew they had to wear seat belts in the back seat.
In order to remind the occupants to fasten their seat belts, there is generally a seat belt reminder device SBR (Safety Belt Reminder) in the front row of the vehicle. We are well aware of the importance of rear seat belts and want to remind the whole family to maintain safety awareness at all times, so we have installed SBRs in the first, second and third rows. “As long as the passengers in the second and third rows do not wear seat belts, the front seat driver can to remind rear seat passengers to fasten their seat belts before setting off," said Gao Feng, head of passive safety in the cockpit department.
The three-point safety belt currently used in the industry was invented by Volvo engineer Niels Bolling in 1959. It has evolved to this day. A complete safety belt includes a retractor, height adjuster, lock buckle, and PLP pretensioner. device. Among them, the retractor and lock are necessary, while the height adjuster and PLP pretensioning device require additional investment by the enterprise.
PLP pretensioner, the full name is pyrotechnic lap pretensioner, which can be literally translated as pyrotechnic belt pretensioner. Its function is to ignite and detonate in the event of a collision, tightening the seat belt webbing and pulling the occupant's buttocks and legs back into the seat.
Gao Feng introduced: "In both the main driver and passenger driver of the Ideal L car series, we have installed PLP preload devices, and they are in 'double preload' mode, that is, waist preload and shoulder preload. When a collision occurs, the first thing is to Tighten the shoulders to fix the upper torso on the seat, then tighten the waist to fix the hips and legs on the seat to better lock the human body and the seat through two pre-tightening forces in two directions. Provide protection.”
"We believe that flagship-level products must provide flagship-level airbag configurations, so they are not promoted as a focus." Gao Feng said that Li Auto has done a lot of research and development verification work in terms of airbag configuration selection. The series comes standard with side airbags for the front and second rows, as well as through-type side air curtains extending to the third row, ensuring 360° all-round protection for the occupants in the car.
In front of the passenger seat of the Li L9, there is a 15.7-inch car-grade OLED screen. The traditional airbag deployment method cannot meet the passive safety requirements of vehicle airbag deployment. Li Auto's first patented passenger airbag technology, through detailed early research and development and repeated tests, can ensure that the passenger is fully protected when the airbag deploys and ensures the integrity of the passenger screen to avoid secondary injuries.
The passenger side airbags of Ideal L series models are all specially designed. On the basis of traditional airbags, the sides are further widened, allowing the front airbag and side air curtains to form a 90° annular protection, forming better support and protection for the head. , to prevent people from sliding into the gap between the airbag and the door. In the event of a small offset collision, no matter how the occupant's head slides, it will always be within the protection range of the airbag, providing better protection.
“The protection range of the side curtain air curtains of Ideal L series models is very sufficient. The air curtains cover below the door waistline and cover the entire door glass to ensure that the occupant’s head and body do not hit any hard interior, and at the same time prevent The occupant's head is tilted too far to reduce damage to the neck. "
03
The origin of outstanding details: How can we empathize without personal experience?
Pony, an engineer specializing in occupant protection, believes that the motivation to delve into details comes from personal pain. "We have seen many cases related to seat safety, in which users were injured in collisions. Based on these life experiences, we will think about whether it is possible for us to avoid similar accidents and whether it is possible to do better than other companies. ?”
"Once it is closely related to life, all details will become a crucial event, worthy of 200% attention and maximum effort." Zhixing said about the seams of the seat cover. Since the airbag is installed in the seat, it is closely related to the frame and surface. When the sleeves are connected, we need to soften the seams on the opposite sleeves and use weaker sewing threads so that the seams break immediately when exploded to ensure that the airbags can explode at the specified time and angle along the correct designed route. The foamed splash should not exceed the standard, and should be sufficiently softened without affecting the appearance and daily use. There are countless examples of this dedication to excellence in detail throughout this business.
Pony found that many friends around him found it troublesome to install child safety seats and were unwilling to install them, but this would seriously affect the safety of young children in cars. "To this end, we equip the second and third rows of ISOFIX safety seat interfaces as standard to provide a safer riding environment for children. Parents only need to put the child seats in the second row and push them backwards to quickly complete the installation. We We conducted extensive tests on the length and installation angle of ISOFIX metal hooks, and selected more than a dozen common child seats on the market for repeated testing and optimization, and finally achieved such a simpler and more convenient installation method. "Pony has experienced installation for his own children. Child seats are a terrifying experience that requires so much effort that one breaks into a sweat. He is extremely proud of the optimized design of the ISOFIX safety seat interfaces for the second and third rows.
We have also worked with child seat brands to develop a child forgetting function - once a child is forgotten in the car and the owner locks the car and leaves, the vehicle will sound a siren and push a reminder through the Li Auto App.
Whiplash is one of the most common injuries sustained in a rear-end car accident. Statistics show that in 26% of rear-end collisions, the heads or necks of drivers and passengers will be injured. In view of the "whiplash" injuries to the occupant's neck caused by rear-end collisions, the collision safety team also conducted as many as 16 rounds of FEA (finite element analysis) and 8 rounds of physical verification to analyze and solve every small problem. , more than 50 rounds of plan derivation were conducted, just to ensure that the damage of each user during a collision can be minimized. Seat R&D engineer Feng Ge said, "In the case of a sudden rear-end collision, theoretically it is not easy for the occupant's head, chest, abdomen and legs to be seriously injured, but even if there is a slight possibility of risk, we don't want to let it go."
In order to avoid "whiplash" safety hazards, Ideal also insists on using two-way headrests. For this reason, it has been misunderstood by some users and is considered to be not "luxurious" enough.
Zhixing explained: "The main function of the headrest is to protect the neck. In order to improve comfort, the four-way headrest with the function of moving forward and backward will generally move backward to increase the gap value behind the head and exceed the design state. In this case , in the event of a collision, the headrest's protective effect on the neck is reduced, and neck injuries will increase, while the two-way headrest 'forces' the customer's neck and head to be fixed in a safer position. "
Users often add neck pillows to their headrests in order to be more comfortable. "It's actually very dangerous. 'Whiplash' during a rear-end collision will increase the risk of neck injury. When a collision occurs, what we need to support is the head to prevent it." The head is thrown back, not the neck, which is why the ideal headrest comes standard with comfortable soft pillows," said Wei Hong, cockpit and exterior simulation engineer.
"For our seat safety team, 100% safety is not enough. We have to achieve 120% performance to be considered qualified. Such self-requirements do not allow us to be imitators. We must go deep into seat safety When it comes to sex and comfort research and development, you have to have the final say and control your own destiny. This is the meaning of our team's existence.
Although the preparation is complicated, we dare not save labor, and although the taste is expensive, we dare not reduce material resources.
At Li Auto, we always insist that safety is the greatest luxury.
These hidden designs and invisible "kung fu" on ideal car seats can protect every family member in the car at critical moments, but we sincerely hope that they will never be put to use.
Post time: May-14-2024