In recent years, everyone's awareness of energy conservation and emission reduction has increased unprecedentedly, and I recently encountered such a brain question:
"Why are no consumers paying attention to the thermal insulation performance of car bodies?"
The questioner's point of view is: "Especially for electric vehicles, if good insulation glass and insulation body materials are used, it only takes relatively little energy to open the air conditioner in summer to maintain coolness, and only a relatively small amount of energy is needed for heating in winter, which is also a means of saving electrical energy." ”
The car was a moving house, and I think he probably referenced the architectural design. If you look at the house in the northeast, the wall is generally designed to be thick, and the use of double-layer glass can prevent external cold air from entering the room, and also ensure that the indoor heating will not be lost.
So the question seems to be a brain hole, but in fact, it is quite scientific, and the car air conditioning power is between 3 and 5 kilowatts, calculated according to the summer use of 2h, almost consume 6 to 10 kWh of electricity. Air conditioners, as a large energy consumer, if there is a body insulation design, it will definitely help save energy.
Cars really have to learn from
We look at it from a long enough time period that cars do borrow architectural design, such as double glazing and sun blinds have become common on B-class cars. Sunshades naturally needless to say, double-layer glass because of the dry air layer sandwiched in the middle, can cut off air convection and conduction, with heat insulation and sound insulation effect.
However, strictly speaking, double glazing was used for safety reasons, allegedly related to the windshield rupture accident of Henry Ford Sr.
In the 1930s, Henry Ford, the founder of Ford Motor Co., was slightly injured by a shattered windshield fragment, which prompted Ford to invent laminated safety glass.
There are similar "surprises", since the 1970s, the body of the car is made of galvanized steel sheet, so that the body will not be used for three or five years before corrosion, the life is more than doubled. Just like the tin house is prone to rust and leakage, the lifting of the body steel plate indirectly provides a guarantee for the durability of the car's thermal insulation.
Of course, it can be understood, after all, until 1954, General Motors first installed a combination of cold and warm air conditioning on nash brand cars, which basically has the function of controlling the temperature and humidity in the car.
In the early years, cars were also designed with openable triangular windows, which played a big role in ventilating the interior of the car and increasing the wind resistance as much as possible without driving the doors and windows. The air conditioning configuration we are accustomed to now is actually only popular for more than two decades.
So with the development of the times, is there a targeted thermal insulation design?
Obviously, the engineers noticed this problem, and for the performance of the car insulation design, the modern automotive engineering design concept really formed a set of rules and test methods.
The key to thermal insulation design is "tightness"
Although the car is not to build a house, the car is a piece of steel plate spliced together by means of welding, gluing and other means, corresponding to the construction of the house, bricks are steel plates, cement is the adhesive. This enlightens everyone that ensuring tightness is the key to improving the level of insulation.
If you compare the old car of the 90s with the new car of the present, you will find that the term "rat hole" is much less. This is because with the improvement of process and manufacturing level, the use of sealant in the overlapping part increases, the reasonable allocation of tolerances and data optimization, the body has basically eliminated more than 5mm rat holes.
In addition, new cars also use more and more sealing strips, which are widely used in areas such as four doors and two covers and sunroofs to fill the gap between body parts. Of course, the sealing strip is not once and for all, it is recommended that everyone should regularly check the sealing strip, whether it has hardened, deteriorated, broken, cracked and broken.
"Four doors and two covers" is a collective name for four doors + front engine cover + trunk cover. Sealant according to the material is divided into dense glue, sponge glue and hard rubber three kinds, rubber material of the sealant strip in waterproof, sealing, anti-aging, sound insulation effect are superior to the other two.
In order to ensure the convenience of car installation and painting, the body will inevitably reserve many holes, and some holes will leak smoke or air if they are not blocked well after use.
How to improve this problem, in addition to plugging holes, there is also a "bypass sealing" design, in short, to add expansion film to the key areas to block.
This film is very clever, it has the characteristics of heating will expand, coating electrophoresis temperature is low will not expand, so it does not affect the electrophoresis liquid to cover the entire body, to ensure corrosion protection. When it enters the electrophoretic drying chamber, the temperature rises, and it immediately expands and fills the entire cavity, achieving the effect of sealing.
With so many solutions, it will definitely take an evaluation test to perfect it in the end. Therefore, engineers designed the crew compartment air tightness test. For example, we have heard of the use of smoke to judge the shape of the streamlined design, study the improvement of wind resistance, in fact, there is also a crew compartment smoke test in the car. Or simply add pressure directly to the car to judge the pressure leakage of the whole vehicle.
Usually the set value is the internal and external pressure difference of 250pa, this pressure value is the pressure value when the airflow of the air conditioning system reaches the middle and high levels, so it is still very representative.
Can you further improve the level of insulation?
From the perspective of technical means, the current thermal insulation technology focuses on the following means:
Use sun blinds, sunscreens and other means to reduce heat radiation;
Use various sealing means to seal the gap and reduce thermal convection;
Double-layer glass and other means are used to reduce heat conduction and heat convection.
The above mentioned concepts have been formed and matured more than a decade ago, if there are any improvements now, it is that the measurement methods are more scientific, accurate, and the improvement of structural technical details.
For example, the body pressure relief valve reconciles the relationship between the air tightness of the vehicle and the amount of leakage. The body pressure relief valve is a one-way air valve used to release excessive pressure in the cabin, which ensures that the interior of the car is not too stuffy due to too high air tightness.
So why do we rarely hear about insulation technology now? And there are no special new methods emerging.
This is because the interior of the car is too tight, which is not necessarily a good thing. The most intuitive reason is obviously that the input cost balance has been broken. Of course, these configurations, like sun blinds, if they can be equipped, are definitely the best. But it increases the risk of door noise, so the control accuracy requirements are more stringent. This shows that the various parts of the car are a systematic project, in fact, when calculating costs, we can not simply estimate the cost of a single piece.
Sun blinds are parts that are prone to abnormal noise.
In addition, in order to maintain the high point of tightness, it is possible to break other designs, such as reducing the process hole, which may lead to electrophoretic paint not being able to completely cover the body, corrosion resistance will be reduced, or the use of more sealing materials will bring about weight gain problems.
Moreover, in the cold winter and summer, there is an increase in fuel consumption, everyone has already done a good job of psychological construction, if the cost increases, but the energy-saving effect is still not prominent, the manufacturer will certainly be cautious to adopt.
The words are not rough. I have to say that compared with the high return on investment brought about by the configuration of science and technology, in fact, the more traditional and mechanical things look, the lower the return on investment ratio. Of course, this is one of the reasons why luxury brands can open up the gap.
Asteron summary
Let's return to the opening question – "Why are no consumers concerned about the thermal insulation of car bodies?" ”
Do you think this question is brain-opening?
I don't think you'll feel that way anymore. Seemingly brain-hole questions, engineers have long been paying attention to and proposing a series of solutions. Obviously, we consumers will not pay attention to the thermal insulation performance of the car body when buying a car, because it belongs to the invisible and untouchable indicators, and the impact on the car is not very large, even if it is an automotive engineer, I am afraid that it is not a duty counterpart, and I do not know that there are also vehicle air tightness requirements.
But if you look at this brain hole problem carefully, I think it still has discussion value, which shows that everyone's awareness of energy conservation and emission reduction is getting stronger and stronger, and the details that everyone did not pay attention to before have also been paid attention to. This also warns auto companies that while advancing in science and technology, the improvement of traditional technology will not fall behind, otherwise consumers will knock you.
Figure | Network and Yaston live shooting
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