Hello, everyone, I am the president of the Electric Vehicle Commune.
In the President's Tucki P7 interest group, the friends had a heated discussion about whether to choose a larger 19-inch wheel hub.
there is only one reason to choose it: it looks good!
and to be honest, the optional price of 5, yuan has raised the temperament to a higher level, and it has also been upgraded from Maxxis VS5 tire to Michelin PS4, which is fully worth the ticket price.
In fact, when Tucki P7 was just launched, the NEDC battery life of the 76 really attracted the attention of many friends.
However, because it is the lowest version, it is not equipped with L2 autopilot system, and the configuration is not high enough, so not many riders choose it, only 2%.
However, the number 76 was dug out bit by bit by details:
First, the L2 autopilot module, which consumes electricity, was abandoned, and the weight was reduced by 25kg, which reduced the power consumption at low speed. In addition, the low wind resistance hub cover can reduce the power consumption at high speed, which has achieved this achievement of long battery life.
That is to say, when P7 was just released, it used the official certification method, which increased the battery life by an additional 5 kilometers!
in addition to the official, there are many "indigenous methods" for old drivers in the private sector.
For example, put on a lower rolling resistance tire with better economy, or push the tire pressure higher, or even throw away the vehicle tools behind ... It is said that the oldest driver can run 1 kilometers longer than NEDC!
Is the old driver's method really so magical? What are the doorways in this?
today, the president will have a good talk with you.
actually in Tesla Model? When it was first listed, many foreign friends had already tested how big the battery life gap was with or without hub cover.
However, judging from the results, it is quite metaphysical:
An electric rental company in Germany can improve the real endurance by 2.6% at a speed of 15km/h; The test result of a broadcaster shows that the power consumption is reduced by 4.1% at the speed of 112 km/h.
as for the more authoritative Car magazine car? and? Driver, the conclusion is that under the environment of 6℃ and 2.8Bar tire pressure, the speed of 8, 113 and 145 can run 3.2%, 2.8% and 4.7% more respectively.
if this is a Tesla Model with a long rear-drive life? 3, can improve the battery life of 2-3 kilometers!
it's no wonder that new energy vehicles such as Tucki P7 and BYD Han are not stingy with the cost of this small hub cover-improved endurance, but it's real!
of course, it's not just the hubcap that can improve the endurance.
for most models, the tire pressure for inflating the tires according to the instruction manual is generally between 2.3 and 2.6.
and Tesla Model? 3, we used the 2.9Bar tire pressure far beyond other brands, making the tire more "drum" and harder! It is said that it can increase the cruising range by 1% compared with the tire pressure of 2.3Bar.
there are Model, too? S car owners reported in the forum that the power consumption has soared from 2 to around 23 after replacing a bigger wheel hub.
the president can't help but be curious: it seems that all the problems point to the two chief culprits, the wheel hub and the tire. Besides, it seems to be related to friction?
However, the following case is even more wonderful:
On the Internet, there are many geometric A owners who criticize the tire size.
perhaps for aesthetic reasons, compared with the mid-low model, the top model of Geometry A has directly upgraded its hub from 16 inches to 18 inches, which is 2 inches larger.
according to the previous Tesla Model? According to the owner of S, the battery life should be reduced.
however, the endurance of the high and low models of Geometry A is exactly the same!
is this related to the 1mm tire size reduction complained by car owners?
To know why, the president has to tell you a little bit about why the car runs. According to the knowledge of middle school physics, when the force is balanced, the object will remain static or move at a uniform speed.
I believe that although you have returned a lot of things to your physics teacher, you should still remember the most basic knowledge:
(Don't be afraid, you won't really talk about these two formulas)
Don't be scared by the formulas:
If you want to change an object from a static state to a moving state, you need to push it. This force is called traction. The greater the traction, the faster the acceleration.
Of course, this traction should not be too small, just like the strength of a 3-year-old child is not enough to push the car.
wait, why is this? Obviously, the vehicle should move, right?
Do you still remember why the small slider in high school physics doesn't move? Why does it stop by itself when you slide for a certain distance?
-because there is something called frictional resistance.
at any time, the vehicle will be subjected to a relatively large resistance, so that it can stop after the power is cut off, or it tends to stop during driving.
otherwise, all the cars parked on the roadside will drift around under various forces like the Tesla Roadster in space.
so it's easy to move the car forward, as long as the traction is greater than the resistance.
and this resistance is actually not a simple force, but it is actually a strong man group composed of four forces!
The names of these four strong men are rolling resistance, air resistance, breaking resistance and accelerating resistance.
Therefore, various skills to make electric vehicles go further are essentially trying to reduce one or more of these four forces.
interestingly, these four resistances have different sizes in different environments!
Let's take the rolling resistance as an extreme point, which is as follows:
Although the tire is round, due to the action of gravity, the area where the tire touches the ground is not round, but a rectangle.
therefore, the tire pressure warning mark on the dashboard will be like this, and the bottom is the state that the tire touches the ground.
So, in this kind of linear acceleration race, thousands of horsepower racing cars will even make the tires wave!
the wavy tire is not round, and the rolling resistance will naturally be very large.
under normal circumstances, the greater the contact area between the road surface and the tire, the greater the friction and the greater the rolling resistance. Like aion? S with a tire width of 235 is much more resistant than Geometry A with a tire width of 195.
-this is also the reason why the geometric endurance is excellent, but the tire width is being spit out.
in addition to rolling resistance, there is also air resistance, which is actually what we often say about wind resistance.
I believe many people have had the experience of sticking their hands out of the window when they were young, and they will be yelled at by their parents. What you feel is the strength of this strong man with air resistance.
(dangerous action, please don't imitate)
The strength of a strong man with air resistance is not only related to the wind resistance coefficient that car companies like to publicize, but also related to the area hit by the wind! Just as we usually run with our hands open in the wind, we will be more tired than normal running.
but the more important point is actually speed: every time the speed is increased, the wind resistance will increase exponentially. Double the speed and triple the air resistance!
at the speed of 8km/h, the strong traction man needs to take out 6% of himself to overcome the wind resistance.
that is to say, the more vehicles hit the wind and run faster, the stronger the air resistance is.
The third resistance is uphill resistance. Its essence is the same as climbing stairs. We need defying gravity to climb uphill.
the last one is acceleration resistance, which is similar to rolling resistance.
The difference between them is that the rolling resistance mainly exists in the rolling process of the tire, and only by turning the tire can the vehicle move forward;
The acceleration resistance exists in the motor, half axle, differential and other parts that rotate inside the vehicle. Only when they turn first can they drive the tires to turn.
there is another part, which is the work done to overcome the inertia force.
is it particularly hard to understand? Let's imagine:
You are pushing a cart forward at a constant speed. If you push it faster, will there be more force on your hand?
at this time, the acceleration resistance is at work.
moreover, the heavier the vehicle, the faster the acceleration, and the greater the acceleration resistance.
So, in essence, the daily state of the car is these three kinds:
More traction-acceleration;
the resistance is stronger-slow down;
traction and rolling resistance are equal-uniform.
the traction is related to the motor of the car, and we can't change it, so the only way to make the car go far is to find ways to reduce the four resistances mentioned above.
With regard to the approximate proportion of these resistances in power consumption, the President made a list for the large and simple families:
Urban roads
Expressway
Power consumption reasons?
Proportion
What is the reason for power consumption?
proportion
rolling resistance
2%
rolling resistance
25%
air resistance
5%
air resistance
6%
acceleration resistance
75%
acceleration resistance
15%.
in urban roads, it is mainly to accelerate the resistance output; In high-speed road conditions, the main force is air resistance.
the simplest and most direct way is to weaken the air resistance first. After all, it is the chief culprit of the shrinking high-speed battery life.
so Tesla Model? 3. Tucki P7, BYD Han and other models all adopt low wind resistance wheel hub covers to reduce the wind resistance coefficient and improve the endurance.
it is not difficult to weaken the rolling resistance. Just reduce the grounding area as much as possible!
this goal can be achieved by replacing the wheel hub with a smaller size, using a narrower tire, or using a low rolling resistance tire with a more economical formula.
although the power consumption of urban roads is generally lower than that of high-speed roads, the mileage of vehicles in cities will be longer.
Therefore, the acceleration resistance that often appears in stop-and-go is also the object that needs to be taken care of.
But there is no good way to accelerate the resistance-the only way is to lose weight.
the car is hard to reduce, so you have to start from yourself.
if you can lose 1kg, you can save electricity by weakening the acceleration resistance, and the effect is about … .5-1%.
but losing weight can not only weaken the acceleration resistance, but also weaken the rolling resistance. The effect is almost ... .5-1%.
if these two are rounded up, they add up to a cruising range of more than ten kilometers.
of course, if you put less junk in the car, you may be able to improve it.
To sum up, if you want to improve the endurance, you must do these things:
By installing a hub cover or not installing unnecessary ribbons on the car, you can reduce the air resistance;
reduce the rolling resistance by reducing the grounding area and reducing the weight;
Reduce the acceleration resistance by reducing weight and accelerating as slowly as possible.
as long as the strength of the resistance strong man is reduced as much as possible, there is not so much traction, and the endurance can be naturally improved.
So, is it true that the old driver claims that he can run 1 kilometers longer than NEDC?
Let's assume a car with a cruising range of about 65km, which is roughly an account:
By installing the official wheel hub cover, it will be improved by 3%;
by increasing the tire pressure by .3Bar, it will be increased by 5%;
By replacing the 2-inch wheel hub, including weight reduction, it will be improved by 5%;
Try to lose weight by 1kg again, and improve by 2% ...
Theoretically, NEDC endurance can be increased by 65x15% = 97.5km. Rounding it off, it seems that 1km is not impossible.
But the president seems to have found the biggest gap between himself and the old driver-weight!
forget it, I'm going to lose weight.
This article comes from the author of Chejia, car home, and does not represent car home's standpoint.