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Produced by Huxiu Automobile Group

Author: Xiao Man

Header Image丨Visual China

"Ah!" With a loud shout, Zhou Hongyi's "hehe" before closing the car door changed to "no hehe".

The cause of the incident was that Xiao Yong, deputy general manager of GAC Aion, introduced to Zhou Hongyi that the Haobo HT gull-wing door has an anti-pinching design, prompting Zhou Hongyi to actually put his hand in the door gap and press the door closing button, becoming the first person to "test the pinching experience" of the car door with his hands.

It can be said that one really dares to speak, and the other really dares to try it.

So the question is, why do car doors with anti-pinch design still pinch your hands? What is the technical principle behind the anti-pinch design of car doors? Why can't the fancy door designs of electric vehicles today take a step further in terms of safety?

Car door anti-pinch finger, don't be too credulous

Before analyzing why Zhou Hongyi's hand was pinched by the car door, we need to first understand Haobo HT's anti-pinch solution.

It is reported that the anti-pinch function of Haobo gull-wing doors consists of two parts: one is the Hall anti-pinch function; the other is the anti-pinch rubber strip. Among them, the former plays the main role in anti-pinch during the door closing process, and the latter only plays a supplementary role.

The so-called "Hall anti-pinch" uses the magnetic field changes generated when the magnetic ring on the motor rotor shaft rotates to generate a corresponding square wave signal in the Hall sensor. After obtaining the motor's speed and position, the software algorithm can be combined to identify the speed/acceleration changes of the motor. When the change reaches a certain threshold, combined with filtering and anti-pinch algorithms, it can be determined that the current door is blocked by external forces, resulting in a reduction in speed, triggering anti-pinch.

This Hall effect anti-pinch solution is mostly used in car window design, and has relatively mature application standards. Generally speaking, the Hall effect anti-pinch solution can perform normally when encountering large obstacles (such as human body, arms, legs, boxes, etc.) at the maximum movement radius of the door, that is, at the bottom edge of the tailgate.

"If the car door encounters resistance during closing, the resistance will be transmitted to the strut. When the strut encounters the resistance of the lever arm, a large current will be generated. The signal will be transmitted to the gull-wing door controller, which will then stop the door." said Xu Zehui.

The reason why Zhou Hongyi's hand was pinched happened to hit two key points that affect the anti-pinch function. First, Zhou Hongyi stretched out his hand to test at the scissor angle. Due to the short force arm and close to the sensor blind spot, the Hall-induced current mutation was small and the anti-pinch effect was not obvious. Second, it is difficult for the sensor to quickly sense and identify small objects such as fingers, and it is impossible to perform current reversal.

With the double buffs stacked on top of each other, it was a blessing in disguise that Zhou Hongyi was able to keep his hand.

Zhou Hongyi later said that when testing the car door, he saw the door gradually close and pulled his hand down to avoid being completely caught. But if he hadn't pulled his hand down, the story might have ended differently. Zhou Hongyi placed his finger close to the door hinge, so the force exerted by the door on his hand was much greater than 100N. This principle is equivalent to "squeezing a walnut through the door gap."

Although Haobo HT has arranged anti-pinch strips on the outer edge of the door, its working principle is that the anti-pinch strip has different resistance values ​​in normal state and under pressure state, and the change in resistance value can be detected to identify whether the anti-pinch strip is squeezed. But the problem is,If you wait until the anti-pinch rubber strip is squeezed and deformed, your hand will most likely have been pinched.

It is not uncommon for a person to get his hand caught in a car door, but it is not common for someone to "willingly" put his hand in a car door like Zhou Hongyi did. Although Zhou Hongyi made a wrong demonstration, he indirectly conveyed a key point - "the technology of anti-pinch in car doors cannot identify 100% accurately."

However, anti-pinch recognition is only one aspect. The Haobo HT gull-wing door cannot achieve "anti-pinch" in the true sense. It is essentially determined by the characteristics of the electric suction door. Electric suction and anti-pinch are inherently contradictory.

The dangerous "last 6mm"

Electric suction doors are not a new technical configuration. As early as the 1990s, the Mercedes-Benz S-Class sedan W140 had already used electric suction doors. However, in recent years, with the continuous accumulation of new energy vehicles, this configuration originally used in luxury models has been transferred to mid-to-high-end models by more and more car companies, including Ideal L series (part), Haobo HT, NIO ET5 and other models all use electric suction doors.

From the structural point of view, the core components of the electric suction door include electric motors, electromagnetic coils, sensors, etc. There is an electromagnetic coil installed in the door frame. When the door is not completely closed, current passes through the electromagnetic coil, thereby forming an electromagnetic field. When the electromagnetic field of the door is close to the body of the car, the door is completely locked by the electric motor.

The car door has two gears: half-locked and fully locked. When the car door is pushed to the half-locked position (generally about 6mm away from the door lock), the sensing device will receive a signal and then trigger the motor to pull the wire until the lock tongue in the fully locked position flips over to achieve complete locking.

In fact, the relationship between electric suction and anti-pinch is a false proposition. The principle of electric suction design is that it is necessary to overcome a certain resistance when the car door approaches the door lock to close the door. If the anti-pinch device is installed, the car door cannot be closed.

From a functional perspective, electric suction doors have certain advantages over traditional physical door closing methods. The smaller closing vibration of electric suction doors can avoid the potential displacement of some interior rubber and plastic parts, and ensure the stability of electronic components.

It is an indisputable fact that electric suction doors have hidden safety hazards, and the suction force of electric suction doors during closing should not be underestimated. In some evaluation videos, objects such as ham sausages were instantly clamped off, and even hard objects such as chicken feet were crushed after being clamped by the electric suction door and taken out. It is not difficult to imagine the consequences of being accidentally clamped by the electric suction door.

In recent years, accidents involving "electric suction doors pinching fingers" have occurred from time to time. First, a BMW owner had his finger pinched off, and then an Ideal owner had his finger pinched. Despite many painful lessons, there is still no solution to the problem of electric suction doors pinching fingers in the market. Consumers are only reminded in the user manual of the precautions when using electric suction doors.

Therefore, no matter how car companies claim the "door anti-pinch" function, it is not possible to completely prevent pinching.

Doors are an important part of vehicle safety, but they are often overlooked in daily use. Today's new energy vehicles have come up with all kinds of door features, whether it's the electric suction doors that were originally part of luxury cars being moved down to mid-to-high-end models, or falcon-wing doors, scissor doors, gull-wing doors and other door shapes.

But no matter what form it takes, safety is always the first priority.The upgrades brought by the configuration are intended to allow car owners to enjoy the convenience brought by the new functions, rather than for the so-called "face project", which invisibly increases the possibility of causing harm to car owners.

In addition to promoting the upgrades that door configurations bring to the experience, automakers also need to inform consumers in a more specific and comprehensive manner how to use them correctly and avoid potential dangers in advance.