Knowledge point-the function of electronic fan
True or false: For whom does the electric fan cool down?
Water tank engine
Most novice drivers think that electric fans are used to cool water tanks, but have you considered the drag coefficient? The biggest resistance when the car moves forward is wind resistance, because there is no dead angle around the empty ground, and the car moving forward is equivalent to constantly "pushing away" the static air, otherwise the air will become the resistance of the car. If you let the electric fan blow forward at this time, is it equal to slowing down? The answer is obviously yes, so the electronic fan will not blow forward, so how does the water tank dissipate heat?
Keywords: air cooling! The car's middle net (air intake grille) is engraved with spaces. When the car is driving, air will enter the engine compartment through the carved gap, which will continuously cool the water tank. At this time, the rotating electronic fan mainly plays the role of "turning flow", and at the same time, the electronic fan will blow backwards to realize heat dissipation from outside to inside for the engine block. Even if two sets of electric fans run at the same time, it is no exception in theory. This is the core function of the electric fan, so it is not difficult to understand why it is "intermittent".
Ambient temperature and water circulation cooling system
Fuel-fueled cars are equipped with [internal combustion engines]. Its principle is that the fuel burns in the cylinder to generate heat energy, and then converts the heat energy into mechanical energy-heat energy is the source power of the vehicle, so it is very important to ensure that the heat energy is not excessively lost and convert more heat energy into mechanical energy (effective work). According to the second law of thermodynamics, thermal energy will be conducted from high-temperature environment or objects to low-temperature objects in disorder, which means that low-temperature objects will absorb heat. Then, if the temperature of the engine block and circulating antifreeze coolant is too low, it will absorb heat energy. Should electronic fans run at the same time? Refer to the picture group below.
Figure 1: Mechanical structure of engine block
Figure 2: Anti-freezing cooling water circulation system
After starting the engine to reach the warm-up state through normal driving, although the engine will generate high temperature when running, and the circulation of coolant is enough to ensure the constant temperature of the engine in the "low load state", it is still necessary to cooperate with a group of electronic fans to dissipate heat from the outside. At this time, if two groups of electronic fans work at the same time, external air cooling will reduce the body temperature below the optimal ideal temperature standard; The engine block with low temperature absorbs the heat energy generated by combustion, which leads to the decrease of engine power. In order to compensate the power, it is necessary to increase the driving speed, and high-speed driving will inevitably increase fuel consumption.
"Double-fan operation" requires the engine to have a high operating load, otherwise the engine block can not control the temperature ideally through coolant circulation. For example, in the hot summer, when the air-conditioning switch is turned on in the congested road section, the compression of the air-conditioning switch will actively improve the idle speed and running speed, and the high temperature baking on the ground will make the body temperature very high, so two groups of electronic fans run at the same time. Similarly, the temperature of the engine block will be very high when driving on the highway for a long time. At this time, two sets of electronic fans need to run at the same time to ensure that the engine does not heat up.
Summary &; On the contrary, if you drive in the cold winter with tens of degrees below zero, the electronic fan will not rotate and the temperature of antifreeze coolant will not rise (it is difficult to raise the water temperature). At this time, many large trucks will block the air intake grille with "wind shields" to reduce the natural cooling of the body by cold air. Only in this way can there be warm air after the water temperature rises. In this state, if two groups of electric fans rotate together, will the water temperature rise?
If the water temperature cannot be raised, it will continue to absorb the heat energy of the engine for a long time. In fact, the torque is reduced by temperature, (torque × rotational speed ÷9549)× 1.36= horsepower. Because the temperature drops, the torque can only get reasonable horsepower (power) by increasing the speed-the fuel consumption will rise again. This is why electric fans need to "run alternately". The electronic control system uses a temperature sensor to control the alternation of electronic fans. Did you get a look at him?
Million car purchase subsidy