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  7. Haitiansheng "flame" Jeep Freeman...

[YesAuto Technology] Airtight, damp, hot, sweaty, this is how I felt 40 hours after receiving an invitation to Sanya, the place where the “Haitian Shengyan” is produced, but unfortunately, I was not at that “party” Body”, but in a Jeep Freeman engineering prototype that has been exposed to the sun for 3 hours. Why am I in that car? Please continue to look down.

Why did I come to Sanya?

If you have seen my colleague Zhang Ge's test drive experience on a plateau with an average altitude of more than 4000 meters (click to review), you will understand the origin of this freeman with a “leopard” paint-test Stage trial installation. The meaning of their existence is to run around and test their reliability under various extreme conditions. After climbing the mountains, it's time for them to go to the “sea of fire”.

The annual average temperature in Sanya is 25.4 degrees Celsius, and the annual sunshine duration reaches 2563 hours. There are more than 300 days of sunshine in 365 days a year, which is basically the rhythm of “sea and sky.” At the same time, it belongs to the tropical ocean monsoon climate, which takes into account both high temperature and high humidity. If you have been to Sanya or live on the beach, you must know the feeling of stickiness all over the body all the time, and this is what this freeman wants feel.

The two Freeman trial vehicles will stay in Sanya for a few weeks and undergo a test of at least 5000km. This includes the reliability test, dynamic test, air conditioning system test, etc. of the vehicle under high temperature and high humidity environment. I will walk with these test engineers in front of me to experience the test of the air-conditioning system.

How do they test? Data analysis + subjective feelings

1. Data analysis: the data is accurate to 0.0001

This is the scene I saw when I opened the door to get into this freeman. Although it was the first time I saw it, I was not surprised. In my mind, it should look like this inside a test vehicle during the verification phase. .

These seemingly messy “wires” are detectors used to test the temperature inside the car. They are distributed on the four air outlets on the center console, above and below the front and co-pilot seats, above and below the heads and feet of the rear passengers, and on the roof and back. Sight glass, and engine compartment.

Each detector is composed of two metal wires, which are divided into positive and negative poles, and sense temperature through current. Generally, the set temperature of our car air conditioner is accurate to 0.5 degrees Celsius, but in the engineer’s measurement, this accuracy is divided into two aspects: one is the measurement temperature accuracy of the sensor, and the second is the acquisition temperature accuracy of the device, the sensor It will be accurate to 0.1 degrees Celsius, and the device collection is retained to four decimal places, which is 0.0001 degrees Celsius.

Of course, today's test is mainly for overall control. When a more subdivided air conditioning team comes, there will be more than 40 sensors in the cabin. Because the interior of the car is a constantly changing temperature field, in order to investigate the temperature of the position where the occupant may ride, they will place temperature sensors on the head, left and right shoulders, left and right hands, left and right knees and legs of the occupant; The total number of sensors arranged in the car will reach more than 100.

2. Subjective feeling: just to make you more comfortable

The data will collect the temperature points of some key parts of each position where the occupant may ride, such as head, feet, knees, etc. This part is to investigate the air outlet temperature of the air conditioner, and more importantly, to examine the occupant's activities Ride comfort in the area, which is also the fundamental purpose of air conditioning testing.

The road test mainly depends on subjective evaluation, and each level (comfort level) is also clearly defined. Everyone who participates in the road test is to be calibrated. The temperature data is auxiliary. For example, if a certain location feels cold, the engineer will call out the temperature data of this part, compare its absolute value and trend, and see if it is below the comfortable temperature zone.

22 degrees Celsius is a temperature tested by engineers, and both comfort and constant temperature ability are very good. It means that you can set it to this temperature directly when you get on the car. Even in extremely hot weather, you don’t need to set the air conditioner to the coldest first. , And then adjust to a comfortable temperature. How to make the air conditioning system cool quickly and achieve it in one step requires constant testing and repeated debugging by engineers to summarize the control logic behind it.

The head is the most important when air conditioning, not only because there are many sensory organs here, but also about 50% of the body's heat is emitted from the head, especially the hair follicle at the root of the human body is the largest radiator. Therefore, when the wind direction is ok, the air conditioner will be comfortable for the head, and other parts will be hot to adjust.

Of course, there may be cases where the head feels comfortable, and other parts of the body such as feet, knees, or arms that are exposed to the sun may feel overheated. However, because the cold air sinks naturally, if the head is comfortable and other places are hot, you can try to increase the cooling to achieve a balance. If the head feels too cold, usually the air outlet is blowing directly to the face. In this case, try to adjust the wind direction to see if it can achieve a balance. In short, the air conditioner must have the ability to maximize the comfort of passengers.

There is no big “body” here, only engineers who want to undress

In fact, of all the tests I followed, the one that I looked forward to most was the 3-hour exposure test. Hmm, enter the ad—”Sun! Just put it here for 180 days.”

Especially in the hot summer, when the car door is opened after the car has been exposed to the sun, I don't think many people are willing to sit in. Generally, we open the window in advance, or repeatedly open and close the door to let the hot air in the car roll away quickly. However, the engineers we tested this time were quite different from what we did. They opened the door, got in quickly, and then hurriedly closed the door for fear that a little hot air would escape.

Isn't this self-abuse? At least in my eyes, it is like this, but there is no way this is work. Of course, I also followed the engineer into this Jeep Freeman that had been exposed to the sun at noon. The first feeling is like a cannon punch with fire from Ryu in Street Fighter on the face (if anyone has ever actually suffered this punch).

This kind of rushing heat is the most memorable. Looking back at that time, it feels a bit like: disgust and disgust, something you can't avoid but you have to bite the bullet. And I found that the “thing” of heat has stamina. After a few seconds of my face adapting to it, the feeling on my body began to come, two words-stuffy and hot! Many people are willing to compare the feeling at this time with a sauna. This is definitely an exaggerated description, because there is no such thing as a scoop of water and charcoal in the car.

After exposure to the sun, the engineer will start the vehicle and idling, put the air conditioning system into working condition, and record the data. After that, this Jeep will do tests on urban road cooling, high-speed road cooling, cooling rate, stable temperature, and stability. Because, in different driving conditions such as cities and high speeds, the engine speed and vehicle speed are different, which is also an influencing factor for the air conditioner, because the compressor speed of refrigeration is related to the engine speed.

This process is boring, because there are only a few things that can be done (in my opinion): constant acceleration, braking, creeping, accelerating, braking, and driving at a constant speed. But it is this boring test that can make our driving more comfortable and safer.

Why is it related to safety? An engineer told me: During the winter test, the car was full of people and kept talking. The outside temperature was as low as -23 degrees Celsius and the humidity was high. The glass had frosted when the car was driving at high speed. Relatively rare and difficult to reproduce working conditions (the driver’s vital capacity is also very large and continues to speak). The engineers immediately modified the defrosting parameters in the control logic, re-released the software version, and verified the changes in the related electronic system, which successfully solved the problem.

After an afternoon of tests under different working conditions, the sun is not so hot anymore, and today's test work has also come to an end. At this point, my high temperature test experience is over. When I opened the door and walked out of the car, the damp air of Sanya immediately hugged me again. I struggled to look back at the Freeman who had not closed the door…

Looked at the swimming pool behind the hotel lobby again, and walked away decisively!

Written at the end:

I only experienced the Jeep Freeman road test one day, but their test was to traverse the four seasons and measured almost all the temperature zones that car owners can encounter. From the extremely low temperature in Heihe/Harbin in winter (the lowest is -38 degrees Celsius), to the 36 degrees Celsius in Sanya in summer, including the 0-25 degrees Celsius in spring and autumn, and the high humidity above 80%, they have their footprints. Even though they did not experience the hottest summer months from June to August due to the limitation of the vehicle development node, they also spent high test expenses in the environmental simulation laboratory to simulate extremely high temperature conditions of 35 to 43 degrees Celsius. The comfort of the vehicle air conditioner is not only for extreme working conditions, but also to ensure that the user experience engineers have tested almost all the temperature zones that can be experienced in the country. (Photo/Text/Photographed by Guo Feng, Car Home)