What was the earliest car door like?
When karl benz first invented the car, it was a three-wheeled car with no doors at all. It looks like human tricycles in the street. Without a door, there is naturally no need for a lock, so the earliest cars didn't have a lock.
With the improvement of people's requirements for comfort, the car slowly appeared a complete compartment that can shelter from the wind and rain, and later gradually became a door lock. But the early locks were completely different from the present ones. The paper "Overview of the Development of Automotive Electronic Locks" published by Li and others in the magazine "Automotive Electrical Appliances" is shared with you.
As mentioned above, it was not until the end of the 1920s that simple mechanical locks appeared on cars for safety and theft prevention. There is little difference between this mechanical lock and the door lock. It can almost be said that it is directly transplanted from the indoor door lock to the door. There is no two-stage locking function, nothing, door bolt.
Due to the continuous improvement of automobile performance, the safety requirements of body parts are getting higher and higher, and the card door lock with 2-gear locking position appears. Now this design has been formulated as a standard by many countries in the world.
Zhou's paper "Accelerating the Step of Eliminating Hook-spring Car Door Locks-Recommend the above patented product TL- 1 Card-type Car Door Locks" published in Automobile and Accessories magazine. Standards of developed countries and regions such as the United States, Europe and Australia. It is stipulated that the car door lock must have two locking positions.
GB 15086-20 13 "Performance Requirements and Test Methods for Automobile Door Locks and Door Clips". It is also mentioned that the common hinged door locks in family cars need full lock and half lock.
Why did you change it like this?
The reason why it should be designed as the second gear lock position is mainly for safety. It's not the designer who deliberately wants to disgust us, but "alas!" This is the only way to shut it down. People have no bad taste, and they can't be shut up without hard work.
Prevent the door from accidentally disengaging.
This paper introduces Zhou's paper "A Preliminary Study on the Technical Level of Foreign Automobile Door Locks in 1980s" published in Foreign Automobile Magazine. What is the purpose of adding a semi-lock? It's not really off. When the car is driving and the door leaves the full lock position, the semi-lock can also play a certain role in insurance.
It's like: when you take out the garbage, you put two garbage bags. In case the garbage bag inside is broken, it won't leak all over the floor. That's what happened. "Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo, Cuckoo.
Or the open door hit the electric car next to it, didn't it? Then we can't order takeout, can we? All this is not good, more locks. According to the national standard mentioned just now, even if the door is in the semi-locked position, it must be able to withstand the lateral and longitudinal loads of 4500N N.
Suppose an adult weighs 70kg, and the semi-locked position can bear the weight of 6 people, which is much more. In case the door accidentally leaves the fully locked position, there will be no immediate danger.
If the door is not closed
In addition, the semi-lock position can also avoid some accidents when closing the door, which leads to the situation that the door is not closed properly. The paper written by Jiang Mingming of Anhui University of Science and Technology is shared with you, which is mentioned in "Research on Structural Optimization of Passenger Car Door Sealing Strip".
The portability of closing the door is related to the lock, hinge, stopper, self-weight, air pressure resistance effect and sealing system. The compression force of the sealing strip accounts for 30% to 50% of the overall closing force.
The paper published by Liu Liang and others in Enterprise Technology and Development also looks at the evaluation method and influencing factors of automobile door closing force, and gives the same truth. The compression load of automobile sealing strip is 8N/ 100mm, so it is assumed that the perimeter of the door is 4m, one frame, right? Then the compressive force of the optical band is 320 Newton.
It is almost equivalent to hanging a big suitcase full of things outside the car door. If other resistances are included, the total resistance when closing the door can even reach more than1000 n.
So, if you want to close the door, you must use some force. If it is only a light area, even if there is no second lock, the door may not be closed. In this case, the semi-locked position can still ensure a certain degree of security.
It's not easy to understand, is it I've said a lot. I tell you, if you think it's tired or difficult to close the door like this, do a small experiment yourself. If you lower the window, isn't there no pressure? Is there wind to ventilate? It closes with a slight turn. You can try.
How should I turn it off?
We don't want to damage the parts of the car, but we want to close the door tightly. Where are the skills and routines? Just now, the paper "Evaluation method and influencing factors of automobile door closing force" has been mentioned above.
Under normal circumstances, under the premise of satisfying the sealing performance, the closing speed range is generally 1m/s, and the error is 0.2m/s. The closer the closing speed is to 1m/s, the better the closing force of the vehicle.
What is the so-called "closing speed"? This is the speed near the door handle when the door is about to close completely. Assuming that the maximum door opening is 70 and the door length is 1m, it is reasonable to open the door to the maximum before closing it, and the force used is about 1 and 2s.
The specific strength of each car is different. In the parking lot or when ensuring safety, you can do experiments and feel it. That is 1, 2, almost 2 seconds to complete the closing action, just right.
It must be closed with some force to ensure safety.
So generally speaking, it takes a little force to design the door to the second gear locking position, and 2s is enough, mainly to ensure safety.
On the one hand, it has better sealing performance, and on the other hand, it prevents falling off. It is definitely not the designer who is in a bad mood, or designed it to disgust us when he is lovelorn today. There is no such thing.