Brothers, Xiaomi SU7 is going to the Nürburgring to set lap times!
Just a few days ago, Carscoops (an overseas website similar to Autohome) posted a message about Xiaomi SU7 setting lap times at the Nürburgring track.
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You know what, as soon as this rice car came under the lens of foreign media, its temperament immediately changed.
This rear wing, this paint, plus the title “Beats Porsche Taycan”, really gives me the feeling of watching the battle between Porsche and Tesla at the Nürburgring.
From all indications, it can be seen that this SU7 is most likely the high-performance version that has not yet been launched. It has a fixed rear wing, wider wheels (the width of the rear wheels may be the 315 previously leaked) and stronger performance.
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The maximum speed even reached 311 km/h.
It’s really fast.
The motor it uses may be the V8s motor with a maximum speed of 27200rpm/min.
This time, the car was photographed doing laps at the Nürburgring Nordschleife, which should be considered the first unofficial appearance of this high-performance motor.
To know how powerful this motor is, just go back and watch the SU7 launch conference.
There was nothing written on the huge screen, just a huge rotation speed data, and it was also called a super motor.
Once this data is put into mass production, it will directly become the number one in mass-produced motors among domestic and even global automobile companies.
Someone will definitely ask, what is the use of this motor's maximum speed?
Because it's not just Xiaomi. New forces like Zeekr and Zhiji will more or less compare this data during their press conferences.
If you can do 10,000, I will do 15,000. Can you also do 15,000? Then I will go straight for 30,000.
It seems that whoever is taller is more awesome.
Look how excited Mr. Lei is. After he became the first, the corners of his mouth are harder to suppress than AK.
But… Can you at least tell us why we need to roll? ヽ(｀Д?)?
Indeed, compared with the configurations that everyone cares about, such as battery life and intelligent driving, the motor speed in the corner may not seem impressive on the surface. But for electric vehicles, it is almost equivalent to the gearbox for gasoline vehicles. In fact, it is a major issue related to the power output of the car.
After all, when it comes to trams, everyone’s first impression should be that they accelerate very quickly, but as time goes by, it’s easy to run out of power.
Indeed, weak acceleration in the middle and late stages is a common problem of most electric vehicles at present, and this is determined by the output characteristics of the electric motor.
First of all, we need to understand a concept. Under the premise that most electric vehicles do not have a shifting mechanism like a gearbox, the speed of the motor, that is, how fast the motor can rotate, actually represents how fast the wheels can rotate.
The conversion formula is roughly like this:
Vehicle speed = speed * π * wheel diameter / 60 * gear ratio
Except for the rotational speed and vehicle speed, the rest are fixed values, so to put it simply, the higher the rotational speed, the faster the car runs.
Don’t feel sleepy, follow my train of thought!
After understanding the relationship between rotational speed and vehicle speed, let's look at a picture like this.
This is a curve showing the torque output of the motor as it changes with the speed. The horizontal axis is the speed, which can be simply understood as the speed of the car. The vertical axis is the torque, which actually refers to the amount of force the car can exert.
It can be seen that when the speed reaches a constant value, the torque of the motor will drop gradually.
To translate it, after reaching a certain speed, the car has no power. It accelerates slowly and has no power, which is what everyone calls the weak rear end.
OK, now if you are an electric drive engineer and want to solve the problem of being unable to continue driving halfway, your method must be: ________.
Who said to replace the motor with an engine? Drag it out!
You must either increase the speed so that the maximum torque output platform can extend as far to the right as possible to cover more vehicle speeds.
Or it can be like the Porsche Taycan, the speed does not need to be too high, 16000rpm/min is enough, but the motor must be equipped with a small gearbox, like the engine, to increase the power at high speed by changing the output gear ratio.
This is why manufacturers are competing fiercely on the highest speed.
If you think about it, you will know that this kind of technology that can make up for the basic shortcomings is definitely not something that can be achieved just by talking.
The engineering problems that need to be solved are basically extremely difficult.
It can even be said thatBeing able to increase the rotational speed without sacrificing other performance basically means that a company is powerful enough.
For example, when something is spinning faster and faster, the most worrying issue is definitely the centrifugal force.
Centrifugal force = mass * angular velocity? * radius
Even if the speed increases only a little, the centrifugal force will increase at a square rate.
A permanent magnet synchronous motor of conventional size will receive a centrifugal force of 130,000 Newtons at 5,000 revolutions per minute, which is equivalent to a force of more than ten tons pulling it. The strength requirements for the rotor are extremely high.
The solution is to use ultra-high-strength silicon steel sheets (the rotor of the motor is composed of many stacked silicon steel sheets) to make the rotor itself harder.
The rotor and stator of the motor are actually stacked up like this.
The second is to wrap a circle of high-strength material around the rotor. For example, the solutions of Tesla and Xiaomi are to wrap a circle of carbon fiber material around the outside of the rotor.
Wrap the rotor like a fence to prevent it from falling apart while spinning.
This is not the end. In addition to centrifugal force, another big problem when the motor rotates fast is that it will heat up. This will not only waste the battery power, but also make the permanent magnet in the motor lose its magnetism, affecting the performance of the motor, and in serious cases, it may even burn out the motor.
How to cool it down? It is not realistic to blow it with a fan. Although it is feasible to use the wind to dissipate heat like a gasoline car, it is basically used to dissipate heat for the battery. If you want to dissipate heat, you can only start from the motor itself.
Most car companies design oil circuits inside the stator of the motor. Since oil itself is not conductive and has a strong ability to dissipate heat, it is definitely the easiest to simply soak the stator of the motor in oil.
The more abnormal car companies, seeing that the stator is oiled, will either make some grooves in the rotor as well, thus the oil-cooled rotor comes into being.
The one in the middle is the oil passage inside the rotor
At this point, my friends will surely say, it seems that these technologies are not very difficult, isn’t it just a piece of cake to increase the speed of a motor?
Indeed, it seems that these technologies are not difficult to disassemble separately, but the chassis of electric vehicles is not as spacious as that of fuel vehicles. There is a large and heavy battery pack placed there. Therefore, the motor must be small and light enough when designing, so as to improve the performance of the whole vehicle without affecting the space inside the vehicle and the size of the battery pack.
Putting so many designs together and making it small and light, doesn’t it feel like the difficulty of research and development has increased suddenly?
So, looking at the manufacturers around the world now, the ones that can really make electric motors short and powerful are either those whose cars are expensive or those whose companies are large. What does that mean? They just have a lot of money to squander.
For example, the high-end new American brand Lucid has a motor that can reach 19,500 rpm/min. The entire assembly is so large and weighs only about 31 kilograms. But the peak output power can reach 500 kW, which is more than 600 horsepower.
The price is naturally very high. The version using this motor starts at at least $100,000, which is basically the same price as the 911.
At the beginning, the high-performance version of Xiaomi equipped with V8s motor is rumored to cost 400,000 to 500,000 yuan. According to Xiaomi's usual low profit margin style, the cost of this car may be really high.
After saying so much, do you have a general understanding of why motors need to run at high speeds?
To put it simply, the reason why car companies increase the speed is essentially to make us drive with more power and more enjoyable.
This is certainly a good thing, but I think that while increasing the speed, data such as battery life and energy consumption that affect the convenience of using the car are also worthy of attention.
After all, just as high-performance gasoline cars consume more fuel, high-power, high-speed motors will also consume more electricity.
For example, a certain new force car model was previously nicknamed “Electric Luxgen” by everyone. The reason is that its super-powerful rear axle motor is powerful, but its energy consumption is also really not low.
If I had to choose, I would rather it had less power, lower energy consumption, longer battery life, and it would also be convenient to charge it less often in daily life.
So at this stage, I think this kind of 20,000-30,000 rpm motor is suitable as a brand's technical label and placed on top models. After all, it is expensive, and those who can afford it will not care about the electricity bill, right?
Should it be made standard on all models? Or forget it, I have to wait until late at night when the battery is low to charge, it’s not suitable, not suitable…
Oh, by the way, do you think Xiaomi can beat the new Porsche Taycan Turbo GT in the Nürburgring?