What are the secrets of the car fuel tank?

There are roughly six "little secrets" in the car fuel tank-there is only one thing to pay attention to when refueling:

Knowledge of automobile fuel tank matters needing attention in automobile refueling

There are many discussions about how to refuel the car, among which at least five knowledge points are needed by novice drivers.

The first thing to know is the volume of the fuel tank, which will be marked in the user manual (automobile manual), but the marked volume is only "safe volume", and there is actually redundancy about 2L. This design has caused many misunderstandings. Let's analyze them one by one.

The concept of durability When driving, do you feel that the first half of the scale (the first half of the fuel tank) is more durable, but the second half of the fuel tank doesn't seem to be "fire-resistant"?

Actually, this is not an illusion, but a fact. The reason for this phenomenon lies in the special design of the fuel tank. The fuel tank shape of the family car instead of walking is not very regular. Unlike the truck fuel tank, the metal fuel tank is designed as a barrel. These oil tanks can be roughly divided into single funnel type or double-cavity saddle type (the two cavities are connected), and their basic characteristics are "big top and small bottom"; That is to say, the upper part itself is larger, but the amount of oil in the oil slick test can only be measured according to the vertical height, so the upper part of the tank oil is more "durable" and has a larger base.

The key point is to assume that the scale indication is 100%, and the upper half box is actually 60%; The remaining oil in the second half of the fuel tank needs to ensure a certain margin, which means that 40% can't be used up completely; Therefore, after the scale line reaches the center line, it is basically not far from refueling preparation.

There is also an important knowledge point here: how many kilometers can the car travel after the indicator light is on? In fact, the reserve capacity standards of all brands of production vehicles are basically "12.5%", and only 27.5% of the oil in the lower part of the fuel tank actually belongs to the "no prompt" normal use standard. So what is the battery life of this remaining proportion?

Simple calculation:

80L volume-40L volume of medium-sized car-small car

The allowance of two cars of different grades is 10/5L, which seems to be a big gap. But the actual cruising range will actually be equal, because the large-capacity car is of course an oversized car, and the maintenance quality will be higher. To put it bluntly, the fuel consumption will be higher, so the remaining 10L will leave a cruising range of about 100 km. If you drive on urban roads, it will be 60/80 kilometers.

The fuel consumption of light compact cars is always low, and it can easily reach 5L/ 100km at high speed cruising. Similarly, urban roads with complex road conditions should be appropriately increased. Therefore, for the target cruising range, the remaining fuel quantity of cars of various sizes and grades is basically the same. It is recommended to refuel within 30-50 kilometers to prevent the fuel from breaking down when encountering a gas station.

(The knowledge points in the first section are tank volume and remaining oil. Let's learn about the oil system and the "fuel-saving mode" of refueling. )

There are two common misunderstandings about fuel tanks, namely:

Adding half a tank of oil saves fuel, and the oil tank has little damage to the oil pump.

Both statements are wrong! Taking the ordinary scooter with 50L (liter) volume as a reference, how much can you actually lose weight under the condition of ensuring that there is only 25L fuel in the car? The density of gasoline can fluctuate within the range of 0.70-0.78 g/cm3. Taking the average value of "1l = 740g" as a reference, reducing the filling amount of 25L can reduce the weight of18.5kg. ..

The fuel consumption standard of light vehicles is roughly [-1kg/1km =-0.00005l], so reducing the fuel consumption of 18.5kg is equivalent to reducing the fuel consumption of 0.00925L. However, based on the 200 km half-tank oil life, the reduction base of half-tank oil is only 0. 1.85 L L L, but the frequency of refueling is much higher. According to the standard of 5 kilometers to and from the gas station, the fuel consumption is 0. 1L/ 1km. Did you consume 0.5L of fuel when refueling? Is it meaningful compared with the fuel saving standard of reducing half a tank of oil?

Important: Will the oil pump be damaged after the indicator light of the oil meter is on?

In fact, it really won't, because the essence of the oil pump is just a motor, and the role of the "pump" is to pressurize the fluid; It is said that there is no essential difference between the white oil pump and the filter pump used in fish tanks, and it is really not easy to be damaged on the premise that they are both motors.

Because the rotor and stator of the motor are not in contact, the rotor is suspended and fixed; In operation, only the rotor bearing of the motor is worn, but the degree of wear is very low, and the heat energy generated is also low. This is why the motor for electric vehicles need not worry about high temperature, and the oil pump will use high-quality materials, so even after the oil is completely cut off, it is no problem to turn off the motor of the vehicle for a while.

Knowledge points: the oil suction port of the oil pump will be at the bottom of the oil tank, and the saddle-shaped main and auxiliary oil pumps are no exception; Therefore, as long as there is oil in the fuel tank during driving, the oil pump can continuously pump oil from the bottom. In other words, as long as the vehicle is not turned off, there will always be fluid flowing in the oil pump, which will dissipate heat during the flow.

Therefore, when the fuel tank is low, the oil pump will not be pumped, but it is still necessary to pay attention to refueling in advance when driving on the expressway; Because the shortest interval between service areas (internal gas stations) is only about 30 kilometers, but the longest can still reach about 65 kilometers. If there is a problem in the service area, it may break down during driving. The problem is not getting injured in a car accident-it will affect driving safety.

(The knowledge in the second section is the fuel-saving way of oil pump and refueling. In short, just fill it up directly, but not too slowly. )

The best way to limit refueling is to slow down directly and shorten the frequency of entering and leaving the gas station to save fuel; But the limit of refueling should also be mastered. The highest standards are suggested as follows.

Fix the locking baffle of refueling gun, automatically refuel until it bounces off, and manually refuel until it bounces off for the second time.

As mentioned above, the calibrated volume of the fuel tank is a safe volume, and there is actually some room left; In this section of air, fuel can be added to the second bounce, and the remaining section of air will still not hurt the car. However, don't try to refuel after refueling, or the carbon tank system may be damaged.

The fuel tank is not absolutely sealed, because gasoline is a highly volatile fuel, which will volatilize gasoline vapor in the environment of tens of degrees below zero. Changing from liquid to gas is the expansion of molecules, and the volume of gasoline vapor will become larger. To put it bluntly, it will "support" the fuel tank from the inside.

If the oil tank is completely sealed, it may be damaged, so it is necessary to design a constant pressure ventilation system, that is, a carbon tank; At the top of the fuel tank, the pipeline connecting the remaining volume (between spaces) is connected to the carbon tank, and the gasoline vapor flows from the pipeline to the carbon tank, and the activated carbon will adsorb the fuel and exhaust the air; After the engine is started, the negative pressure generated by the air intake system sucks air from the breathing hole of the carbon canister, which drives the fuel to participate in combustion.

Knowledge points: it can be filled in any season, even in summer. It is precisely because of the carbon canister system that volatile fuel will not damage the fuel tank and will not be wasted-unless the parking time is too long, even in winter, natural volatilization will be reduced.

The knowledge of automobile fuel tank and oil circuit also needs to know whether it needs cleaning, but it doesn't need to be cleaned with some solvents. Because there is a "fuel filter" in the oil system, its function is to filter the impurities in the fuel, and the oil pump pumps oil from the bottom, so the impurities cannot be hidden. The key point is that the replacement cycle of the filter element is 300/50,000 km, and the replacement cost is relatively low, with the lowest 100 yuan or more, and no solvent is needed.

(The knowledge points in the third section are refueling mode and carbon canister system)

Knowledge 1: some fuel tanks are on the left and some are on the right; The reason is that different cars have different design habits, because in the Commonwealth and Japan, the steering wheel is on the right (right rudder) and vehicles drive on the left; When parking, you should also stay on the left, so of course, the gas filler should also stay on the left. In the early days, there was a portable fuel tank. If you refuel on the left side of the road, you don't have to worry about being hit by a vehicle driving on the right.

On the contrary, mainstream left-hand drive vehicles should put the gas filler on the right side, because there are "right-hand drive" and parking regulations; Because there are many brands of joint venture vehicles, we can see two kinds of vehicles with design habits. The fuel filler can be observed from the symbol of the fuel indicator, and the arrow points in the direction of the fuel filler.

2. The fuel tank of passenger car engineering plastic is not simple, but a very reasonable safety design; Because the clearance between these vehicles and the ground is very low, if the bottom is propped up during the collision, the metal fuel tank may grind sparks and ignite the vehicles. At best, the engineering plastic oil tank will only grind out high temperature, and it can't be an open flame. This is the reason why this material is widely used. Instead, it is a passenger car with a metal fuel tank, which is simply equipped.

It is also reasonable for trucks to use metal fuel tanks. First of all, the ground clearance is high, and the reserves are often thousands of liters. Engineering plastic materials cannot guarantee that such a large weight will not deform during driving.

Some trucks have two fuel tanks. What design is this? This kind of fuel tank is called double-cavity fuel tank, and the two cavities are separated. The chamber is used to charge diesel oil in winter. This kind of diesel oil is expensive, but its freezing point is low. To put it bluntly, it can prevent freezing. The filling of the large cavity is 0 # diesel oil, which is cheaper but easy to freeze. Winter begins with a small oil tank. No.0 diesel oil can be melted by exhaust high temperature or electric heating rod. Use a large fuel tank after melting to save the cost of car use.

That's all the fuel tanks. All the basic knowledge points are here.