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[YesAuto technology] I believe that when driving a school to learn a car, the first thing the coach said to us is to wear seat belts. How important are seat belts? With the innovation of active and passive safety technology of automobiles and the upgrading of airbag technology, have the seat belts become tasteless in a collision accident? What secrets are hidden behind the seat belts that we don’t know? With these questions in mind, we then go back to the age of the seat belt and revisit those things about it.

Before talking about seat belts, we first understand a set of data. According to statistics from relevant departments, in recent years, the fatality rate of drivers without seat belts is about 37.7 times that of seat belt accidents. There is no doubt about the facts. The data proves that despite the application of various automobile safety technologies such as airbags, if you don't wear a seat belt, the chances of death are still very high.

– A traffic accident occurred at the 27 second position in the video, and the occupants in the car were thrown out because they did not wear a seat belt

It can be said that the seat belt is one of the most basic and important safety configurations in a car. And where does such a great design inspiration come from? Let's start with the invention of the seat belt.

■ The seat belt fell from the sky?

The seat belt was born long before Karl Benz invented the car. In the early nineteenth century, the British engineer George Cayley invented the seat belt. But in 1885, Edward J. Claghorn of New York registered George Cayley’s invention as his patent. However, the seat belts at that time were far from the seat belts in our cars today. The seat belts at that time were called : A device with hooks and other fixtures specially designed for fixing the human body.

■ The birth of the standard three-point seat belt

Later, humans began to realize that seat belts are not only needed on airplanes, but also on automobiles. In 1955, Ford Motor made the seat belt configuration as an option, and the first model with a standard seat belt was the Saab 93 GT750.

Although more and more cars are equipped with seat belts, the seat belts installed on the car at that time were all two-point seat belts tied to the waist. Due to design defects, this kind of seat belt still has safety hazards. When the car is emergency When braking or colliding, it is unavoidable that the driver's head hits the steering wheel or windshield, causing casualties.

It was not until 1959 that Volvo engineer Nils Bohlin invented the three-point seat belt. This invention has far-reaching influence. From its birth to today, it has saved people's lives in tens of thousands of accidents. Moreover, it was rated as one of the eight most important inventions of the past 100 years by the German Patent Office.

Since the three-point seat belt did not receive much attention after its introduction, in 1963, Volvo tried to vigorously promote the three-point seat belt in the United States and other markets. They conducted a series of safety tests and the results showed that vehicles using this three-point seat belt In the event of a collision, it can greatly reduce the chances of injuries and deaths of people in the car.

Nils Bohlin's three-point seat belt later developed into our standard three-point seat belt. It is worth mentioning that Volvo did not exclusively share the invention of the three-point seat belt, but shared it with the world. Any car factory can use this patented technology for free. This approach has won global praise.

– Introduction to seat belt history

The birth of the retractor roughly determines the basic structure of the future three-point seat belt. Today, decades later, all automobile manufacturers have adopted this three-point seat belt.

■ In addition to the standard three-point seat belt, what else?

● Two-point safety belt

The early two-point seat belts have not been completely eliminated in this era. At present, the two-point seat belt is more common in the middle of the rear of passenger cars and on ordinary buses. Due to cost and other factors, these passenger cars There is no three-point type, and there is no retractor, just a webbing tied to the waist of the passenger.

● Four-point, five-point and other multi-point safety belts

Compared with ordinary cars, racing cars have higher requirements for seat belts, and the inertia force caused by braking and turning during the competition is greater and more frequent. In order to better protect the driver and help the driver to drive, four-point, five-point or even six-point seat belts are used on the car.

Although the multi-point seat belt is more troublesome than the three-point type, it is not troublesome to unfasten the seat belt, because the multi-point seat belt is generally combined with a quick-release device, and all the seat belts at all points will be released at the same time by pressing a button. .

Multi-point seat belts are not only used in racing cars, but also in child safety seats. Compared with the multi-point seat belts on racing cars, the seat belts used by children are equipped with soft protective pads on the parts that are attached to the body and are stressed.

Compared with standard three-point seat belts, two-point and multi-point seat belts have a common disadvantage that there is no retractor, which means that they must manually adjust the length of the seat belt.

■ Why can't we pull out the seat belt quickly?

We may all have this experience. The more anxious we are after getting in the car, the more anxious we will be to pull out the seat belt. This is due to the fact that we are pulling too fast and the locking mechanism inside the seat belt is locked. Let's start with the structure of the three-point seat belt and analyze why it locks.

The seat belt is a passive safety system composed of seat belt webbing, retractor, buckle, insert plate and other components. When it comes to seat belts, the first thing we think of is this seat belt webbing.

What is often invisible is the key, just as the core component of the seat belt is the retractor hidden in the B-pillar. The invention of the retractor eliminates the need for humans to manually adjust the length of the seat belt.

Unlike spring-driven retractors, motor-driven retractors have more practical functions. Mercedes-Benz C200L is one of the application cases.

– The following video will show you the process of automatically adjusting the seat belt length:

■ Under what circumstances will the seat belt lock?

In emergency braking or downhill, the seat belt can also achieve a mechanical locking function. This is the simplest and most reliable way to protect the driver by using the principle of inertia. In addition, there are also electronic locks on higher-end models. Compared with mechanical locks, it can provide protection under more driving conditions.

In the event of a collision, are these seat belt locking functions protecting us? Please see our technical interpretation of seat belts in collisions.

■ How do seat belts protect us during a collision?

Most people think that at the moment of a collision, the seat belt only protects us through the above-mentioned locking function. In fact, this is not the case. Except for low-end cars such as microfacers, most of our cars today are pre-tightened seat belts with collision pre-tightening function.

■ How do seat belts achieve collision pre-tensioning?

Most of the current pre-tensioned seat belts are deflagration type. This type of seat belt uses the principle of gas deflagration. Its deflagration device is composed of a gas initiator, a gas generating agent, a duct, a piston, a driving wheel, and the like. The deflagration pre-tightening seat belt drive retractor has various structures, such as steel ball type, rope type, rack and pinion type and so on.

The response time of the deflagration pre-tightening seat belt is extremely fast. Taking the steel ball type as an example, the whole process from sensing the occurrence of a collision to realizing the pre-tightening of the seat belt only takes a few thousandths of a second. But its collision preload function is irreversible and can only be used once. When this kind of seat belt exerts a collision pre-tensioning function or reaches the replacement period, it must be replaced. Generally, the cost of replacing a seat belt assembly ranges from several hundred yuan.

■ Will deflagration pre-tensioned seat belts strangle people?

The deflagration pre-tightened seat belt uses the seat belt force limiter to control the force of the seat belt on the human body and avoid the excessive restraint force from strangling people. The principle is to use the torsion principle of the force limiting shaft.

● Another design to reduce the restraint force during collision

The front row of most cars can rely on the joint action of seat belts and airbags to alleviate the impact of a collision, while the protection of rear passengers is relatively weak. Considering this problem, Ford has developed an airbag seat belt for the rear, which can minimize the chance of occupants being strangled in a collision. In 2011, this configuration will be available on the back seat of the Ford Explorer.

– In the future, the new Mercedes-Benz E-Class will also be equipped with airbag seat belts

Having said that, you may want to ask whether we can only feel the credit of the pre-tightened seat belt when we encounter a collision. Of course not, there is a kind of pre-tensioned seat belt that can not only play a role in a collision, but also show its “ability” in daily driving, that is, the electronic pre-tensioned seat belt mentioned below.

■ Electronic pre-tensioned seat belts are used in non-collision situations

Compared with the deflagration type pre-tensioning seat belt, the biggest difference of the electronic type is that its pre-tensioning control mechanism is no longer a gas generating agent but a direct drive by a servo motor. Due to the characteristics of the motor drive, the pre-tensioning process of the seat belt is reversible and can be realized many times. At the same time, it also means that the electronic pre-tensioned seat belt can not only be used in the event of a collision, but also can be tightened without a collision to perform more functions.

It is emphasized that we call the tightening of the electronic pre-tensioned seat belt during a collision as the pre-tightening function, and the tightening in a non-collision is called the automatic tightening. The tightening principle is: when the electronic control unit detects that the vehicle acceleration sensor and other equipment reach the trigger condition, it will send the tightening signal to the control device of the retractor, and then it will stimulate the servo motor to execute the tightening command to complete the tightening. Tight effect.

● TRW’s latest electronic pre-tightening seat belt technology

TRW Automobile Group is currently the seat belt supplier behind many automobile brands. At TRW’s latest technology exhibition, we saw its technical achievements in seat belts. Its seat belt system not only has the advantages of ordinary electronic type, but also features that it combines pre-tensioned seat belts with active safety systems such as the vehicle's automatic brakes, making the seat belts more “smart” to protect the occupants in the car .

TRW’s latest set of pre-tightened seat belts consists of an active seat belt buckle lifter ABL (Active Buckle Lifter) and an active control retractor ACR (Active Control Retractor).

We can understand its principle through the following small video.

Similarly, you can use the following video to understand what special technologies Tianhe pre-tightened seat belts have in actual road applications.

Edit summary:

From the simplest belt tied around the waist to the seat belt system incorporating more safety technology, from incomplete protection during collision to active electronic tightening in non-collision situations, more than a century of evolution has allowed seat belts To hold us more “smartly” in the dark, make the car more like a creature with the consciousness of actively protecting us. We may not pay too much attention to the changes in this “silent dedication” seat belt in the car. Some drivers even regard it as a burden and never wear it, but when a collision occurs, the seat belt protects our lives. Vital. So I warn everyone: Get on the road safely, please wear your seat belt! (Photo/Editor Xia Zhimeng of Auto Home)