TU-TESL

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I believe that when you hear the words Quattro, 4matic and xDrive, you will know that it is a car that is not easy to get into trouble. In this era of rapid development of electric vehicles, a variety of new terms emerge in endlessly. For example, extreme four-wheel drive, e-four, double motor all wheel drive and so on. Although they have various names, they are all tough roles. However, for the diehard powder of the internal combustion engine, the four-wheel electric vehicle is a waste, similar to the feeling of "it's useless to see". Today, we will talk about whether this idea is right or wrong from two aspects of mechanical structure and actual experience. Let's start with a user perspective. At present, electric vehicle users are most concerned about two factors: price and endurance mileage. Because four-wheel drive is almost expensive, in this extremely sensitive market segment, it is not a key consideration at this stage, so the vehicle performance is put in a very secondary position. Even so, there are still a small number of performance oriented vehicles in the electric vehicle market. These models are often four-wheel drive systems, such as performance series, es8 / ES6 performance version, Tang ev600d, and a ion LX 80D, which are very performance oriented vehicles. In this way, users who don't buy a car will ask, how different is the driving experience of these electric four-wheel drive vehicles with high prices from that of two drive vehicles? In fact, the driving experience of these vehicles in the daily urban road is not very different, I think there are two main points. First, the most intense feeling is that the acceleration is really fierce and the back pushing is extremely strong, because the acceleration time of these models is within 5S, and the linear acceleration ability can really match a large ticket. Second, the stability of the electric four-wheel drive vehicle will be slightly better than that of the two-wheel drive vehicle, especially on the slippery or low adhesion road. Besides, you can hardly feel the difference between a four-wheel drive and a two-wheel drive. Although the ultimate goal of both is to realize the four-wheel drive function, the four-wheel drive structure of fuel vehicles and electric vehicles is quite different. Traditional fuel vehicles are divided into three types: time-sharing four-wheel drive, timely four-wheel drive and full-time four-wheel drive. Among them, full-time four-wheel drive means that the four wheels have power under any circumstances, but the power distribution of each wheel will be distributed according to different situations; the time-sharing four-wheel drive is controlled manually, and the driving force of the four wheels is the same when the four-wheel drive is connected, which cannot be changed; the timely four-wheel drive means that the four-wheel drive is given when necessary, usually two-wheel drive is the main driving force. But no matter which form, there is only one power source, that is, in the front cabin, and it needs to rely on the transfer gears, transmission shafts, differentials and other transmission components with complex structure to realize four-wheel drive. Different power distribution modes create different driving modes. The power source of electric vehicles can be more than one. At present, the commonly used way is to install a driving motor on the front and rear axle respectively, and two motors control the front and rear wheels independently to realize four-wheel drive, which is the most essential difference between fuel four-wheel drive and electric four-wheel drive. The biggest advantage of dual motor four-wheel drive is that it can realize all kinds of driving modes through system control, including full-time four-wheel drive, time sharing four-wheel drive, timely four-wheel drive, front drive and rear drive, which can be said to change if you want. Many manufacturers call it intelligent four-wheel drive. But not all cars have the same front and rear motor power. Some cars have different power between the two motors. ECU distributes torque to the front and rear wheels under different road conditions, which is a relatively advanced full-time four-wheel drive. Since it's a four-wheel drive system, you will naturally think of the off-road problem. As for whether we can cross-country or not, let's first draw a conclusion. At present, electric four-wheel drive is mainly used to deal with rain and snow or light cross-country sections, not designed for extreme road conditions. It's very different from the hard off-road vehicles in your impression. There are two reasons for not being able to cross-country seriously. First of all, many people are saying that the electric four-wheel drive is not reliable. No power means that the four-wheel drive fails. But this is an obvious question. Can you drive a fuel car without fuel? Let alone four-wheel drive. Of course, the four-wheel drive of electric vehicles is subject to the battery power, and there is a certain gap between the endurance and fuel vehicles. The fuel is easy to carry, but the power battery can't be carried for backup. The lack of power can only be solved by charging, especially in the field, don't even think about charging the power battery. Secondly, we should also be clear that many hard-working off-road vehicles are used in extreme environment, and the maturity and safety of electric four-wheel drive need to be verified. For example, when passing through the wading road section, it is very easy to form a safety hazard for the electric four-wheel drive system with more circuit structure. In addition, a higher ground clearance is required to pass the off-road road section, and the traditional fuel off-road vehicle has great advantages even in the original state of a plain vehicle, let alone a car with a raised modification. However, due to a large number of groups installed in the chassis, the ground clearance of the electric vehicle is only a little higher than that of the car, and there is no advantage compared with the fuel off-road vehicle in terms of trafficability, especially when the battery pack is severely squeezed or deformed, the safety remains to be verified. To sum up, at this stage, in addition to improving vehicle performance, electric four-wheel drive is mainly used to cope with the deterioration of road conditions when the natural conditions such as rain and snow change, that is, to enhance stability. In the future, it will certainly make a difference in off-road aspects, but it is not the time yet. At least after the electric vehicle enters the mature period, manufacturers will have the energy to spend more attention on the handling performance and off-road performance. As mentioned just now, the four-wheel drive formed by double motors may not be the real appearance in the future. Now it is just a transitional stage. Theoretically, one power source per round is the ultimate state of four-wheel drive technology, which is often referred to as hub motor. Its biggest feature is to integrate the drive, transmission and braking devices into the wheel hub, omitting the transmission parts such as clutch, transmission, transmission shaft, differential, transfer case, etc. because the wheel hub motor has the characteristics of independent driving of a single wheel, it can be easily realized in the form of front drive, rear drive or four-wheel drive. One power source per wheel can also make the vehicle react faster and more efficiently without taking up more space, but the problem is that the cost is too high. At present, there are no mass production models using this technology, more of them are on test models and modified vehicles. Of course, the electric four-wheel drive technology is relatively new and not very mature, so the performance of the electric four-wheel drive of different manufacturers is also very different, but the electric four-wheel drive is not useless, the most intuitive feeling is to bring sufficient acceleration performance and enhance stability to the car owners. There are also some criticisms about the electric four-wheel drive, such as the durability and safety of the four-wheel drive system, which need to be known through long-term use. It is the right choice to be hopeful about the electric four-wheel drive.