The principle of car seat belts. The seat belt can be folded, and when not fastened, the body can easily tilt forward. However, when a vehicle collides and the human body quickly rolls forward, the seat belt will suddenly tighten and the human body will be tightly fixed.
Traditional seat belt devices have a stop wheel. If the seat belt is quickly pulled, for example, in a car accident, due to the rapid rotation of the seat belt roller, the internal clip will be removed by centrifugal force, which will quickly cause the seat belt to be locked and the person to be fixed to the chair on the seat. When a person is already protected by an airbag, the seat belt will relax and avoid squeezing the person's ribs. To achieve the goal of ensuring the safety of drivers and passengers through a series of actions mentioned above.
The internal structure of the seat belt device varies depending on the model level and complexity. More advanced seat belts also have pre tensioning devices and tension limiters. You can quickly pull the car seat belt and lock it because there is an inertia block in the seat belt. When the speed reaches a certain acceleration greater than or equal to 2.0g, lock the internal ratchet and internal gear. This type of lock is called driver sensitive. There is also a type of car motion sensitivity that is used when the car is up, down or rolling.
Seat belt structure
The safety belt consists of a webbing and a retractor, a buckle, a guide device, a height adjustment mechanism, a tensioner, and a locking device. The safety belt retractor can be slowly pulled, and fast pulling is the locking principle.
In the seat belt system, the seat belt is connected to the retractor. The core component of the retractor is the reel, which is connected to one end of the seat belt. Inside the retractor, the spring provides rotational force (or torque) to the reel to rotate and tighten the loose seat belt. When pulling out the seat belt, the reel rotates counterclockwise and the connected spring also rotates in the same direction.
The following is a schematic diagram of the design that locks and rolls when the car hits something. When the car comes to a sudden stop, inertia will cause the pendulum to swing forward. Push the pawl on the other end of the pendulum upwards, and the pawl catches one of the ratchet teeth, preventing the gear from rotating counterclockwise, thereby preventing the connected reel from rotating. When the seat belt is released after being impacted, the gear rotates clockwise, the weight resets, and the pawl and ratchet separate.
The tractor locking system is triggered by the movement of the seat belt. The hanging plate is equipped with a weighted swing link. When the scroll rotates slowly, the swinging link will not swing. The spring holds it in its original position. However, when the seat belt is forcefully pulled, centrifugal force will drive the weighted end of the swing link to swing outward. The slender rocker pushes the cam on the outer shell of the retractor. The cam is connected to the rotating pawl through a sliding pin. When the cam moves to the left, the sliding key moves along the groove of the pawl. This moves the pawl counterclockwise into the rotating ratchet connected to the reel. The ratchet is stuck on the gear teeth and cannot rotate counterclockwise. I found a similar animation form online, which is relatively simple. You can also refer to it, because when a collision occurs, car movement will trigger the retractor to immediately lock the seat belt, and the seat belt movement trigger is the impulse of passengers to move forward after the collision. The seat belt only moves when the seat belt is activated, so the action of the car moving trigger type is faster than the action of the seat belt moving trigger.