If you look closely at the middle net of the new car now, you will find that more and more new cars are beginning to use the active grille that "shuts up". In various car reviews, the introduction of the active grille is nothing more than to make the vehicle have a faster hot car speed in the cold winter. But in fact, the advantages of the active grille are much more than that!
Before introducing the many advantages of active grilles, let's take a look at how they work. In fact, compared to other functions on the car, the working principle of the active grille can be said to be simple to explode, it is like the shutters in our home, but the motor controls the opening and closing, and there is almost no gap after closing.
In operating logic, the active grille is usually controlled by a driving computer (ECU). It can be roughly understood that when the engine is in a low temperature environment that needs to be heated up, or when the engine load is low and there is no too high heat dissipation demand, the ECU will close the active grille to "keep warm" the engine. When the engine's operating temperature is higher than ideal, the ECU opens the active grille to help cool down the engine by introducing cool airflow. As for the timing of opening and closing, the ECU will refer to the coolant temperature of the engine, the oil temperature, the ambient temperature and the speed of the vehicle when driving. In addition, if the vehicle's air conditioning system has external circulation turned on, the active grille will usually also be turned on to provide more fresh air to the air conditioning system.
After introducing the working principle and logic of the active grille, let's take a look at what it can do to help our vehicles!
In fact, in addition to helping the engine keep warm and heat up quickly, the active grille can also help the engine reduce fuel consumption by increasing the heating speed and reducing the wind resistance, and we will introduce it to you in turn.
First of all, the active intake grille can achieve a fuel-saving effect, mainly by increasing the engine's warming speed. This is because after the engine is started in the cold engine state, due to the lower temperature in the cylinder, gasoline cannot be quickly mixed with air by volatilization like in the hot engine state. At this time, the lower gasoline content in the oil-gas mixture will make it difficult to ignite itself. Therefore, in order to ensure that the oil-gas mixture can be ignited normally and then drive the piston to do work, the ECU will increase the gasoline content in the oil-gas mixture by injecting more fuel.
As the engine continues to work, the temperature in the cylinder rises, the volatility of the gasoline injected into the cylinder will be significantly improved, and it will be better mixed with the air inside the engine, so the ECU can stop the instruction of multi-injection. Seeing this, I believe everyone understands that if we can shorten the warm-up time of the engine, it is equivalent to shortening the time of more fuel injection, and the fuel consumption of the vehicle is naturally low. This difference in fuel consumption is especially noticeable in winter scenarios where the heat engine time is obviously lengthened.
In order to shorten the heating time and reduce the amount of fuel injected by compensatory gasoline, the active intake grille that can be controlled to open and close came into being. When the active intake grille is closed, it can avoid the cold air from the low temperature in winter from entering the engine compartment to the greatest extent, and force heat dissipation on the engine. It's like in the cold winter, if you want to make the interior warmer, you must close the doors and windows. And the active grille here is equivalent to the doors and windows of our home.
Not only that, the faster heating speed brought by the active intake grille will also accelerate the heating speed of the oil, and it should be known that the viscosity and fluidity of the oil are closely related to the temperature, and in the low temperature environment, the oil will show an extremely viscous state, which will lead to a decline in fluidity. As the temperature rises, the oil becomes thinner and the fluidity becomes better. Because the oil is in constant contact with many components in the engine cylinder, the oil with better fluidity will also reduce the operating resistance of the engine itself to a certain extent, thereby reducing fuel consumption.
According to a survey report by SAE American Society of Automotive Engineers, after 10 hours of stationary 10 hours in an environment of minus 24 °C and then driving at a speed of 40 km/h for 30 minutes, the engine oil temperature equipped with active intake grille is 5 °C higher than that of models without active intake grille, while the transmission oil temperature will be 4.4 °C higher. In addition, the average temperature in the cabin has also increased from 36.6 °C to 40 °C. It can be seen that the active intake grille can indeed shorten the warm-up time of the powertrain, so that the engine and gearbox can reach the normal working temperature of about 90 ° C as soon as possible.
In terms of fuel consumption, according to the SAE American Society of Automotive Engineers research report, in the environment of minus 7 ° C neDC fuel consumption cycle test, models with active grille save about 7% of fuel compared to unequipped models. In order to avoid the simulation data of NEDC's bench testing not being accurate enough, SAE also conducted actual road tests, and the final measured data differed from the bench data by only about 0.3%. It can be seen that the active intake grille can indeed play a role in improving the fuel economy of the vehicle at low temperatures.
SaE Society of Automotive Engineers in addition to testing at minus 7 °C, found that the active grille can improve the fuel economy of the vehicle, they also conducted a NEDC bench test with an ambient temperature of 25 ° C, the experimental results showed that even in warm environments, the active grille can also improve the fuel economy of about 2%. The increase in fuel consumption in this part is mainly due to the reduction of the wind resistance of the whole vehicle after the active intake grille is closed.
You know, when the vehicle is driving at high speed, the air hitting the front of the car will flow backwards from the three directions of the roof, the cabin, and the bottom of the car. In order to reduce the wind resistance of the roof, the current cars basically adopt the streamlined roof design that everyone is accustomed to, so that air can flow through the roof faster and smoother. In the bottom part of the car, today's new cars are basically covered by a large area of flat skid plate, so that the chassis as far as possible to present a flat state, for the rapid passage of air to provide a flat "runway".
Sandwiched between the roof and the bottom of the car, the front facing the wind is very awkward. Because when the air flow passes through the intake grille into the cabin and flows through the coolant radiator, turbocharged engine intercooler and other heat dissipation devices, it is bound to collide with the scale structure inside the radiator, causing a large deceleration and increasing the wind resistance. This is not the end, because when the airflow enters the cabin, the only exit is the opening at the bottom of the cabin, and once the airflow flows out of the bottom of the cabin, it will collide with the airflow that was originally driving at high speed in the chassis, which in turn affects the gas flow speed in the chassis area and increases the air resistance. Therefore, if the vehicle is equipped with an active grille configuration that can be completely closed at high speed and partially closed at medium and high speed, the air flow into the cabin will be greatly reduced, which is equivalent to reducing the confluence resistance of the cabin airflow and the chassis airflow, thereby reducing the wind resistance of the vehicle.
It is precisely because the cabin airflow will have a great impact on the resistance of the vehicle, so the electric vehicle with relatively small heat dissipation pressure without exception uses an almost completely closed intake grille design to reduce the power consumption level of the vehicle when driving.
According to sae American Society of Automotive Engineers test data, at a speed of 80km/h, the vehicle closing the active grille can reduce the wind resistance coefficient of 0.011Cd for the vehicle, although this value does not look much, but according to the wind resistance formula: wind resistance = wind resistance coefficient × speed × air density × Windward area × 1/2 It can be seen that when the slight change in the wind resistance coefficient is multiplied by the speed, it will have a great impact on the wind resistance. Therefore, as shown in the figure above, as the speed of the vehicle increases, the effect of the active intake grille on the reduction of energy consumption will increase exponentially. For example, at a speed of 80km/h, closing the grille can reduce the power consumption of the vehicle by 0.185kW, and at 105km/h, closing the grille can reduce the power consumption by 0.407kW. Calculated according to 1 kW = 1.36 horsepower, the equivalent of the active grille can reduce the power waste of 0.55 horsepower for the engine at a speed of 105 km/h. In other words, if the grille is turned off when the vehicle is traveling at a speed of 105 km/h, the engine can maintain the vehicle at a speed of 105 km/h even if it is reduced by 0.55 horsepower.
This saves 0.55 horsepower consumption, according to SAE's actual tests of the American Society of Automotive Engineers, can reduce the fuel consumption of the vehicle by 3% at a speed of 105km/h, which is equivalent to a car with a high-speed cruising of 6L/100km, and the fuel consumption can be reduced to 5.82L/100km after closing the active intake grille. It is precisely because the active intake grille can show excellent fuel saving effect at high speed, so the general car companies will set the closing speed of the active intake grille to 80km/h.
The faster warm-up speed brought about by turning off the active grille can not only reduce fuel consumption, but also help passengers in the car to blow warm air earlier in the cold winter. This is because the working principle of car warm air is to blow the heat of the coolant transferred to the heat exchanger into the car through the air conditioning fan, and the coolant is the liquid circulating around the engine, so if the engine can heat up quickly, the coolant can naturally heat up quickly with the engine. This more comfortable warm air experience brought by the active grille will be more pronounced in the farther north as the perception becomes. This is also why active grilles are more likely to appear in luxury cars where user experience is paramount.
According to the experimental data of a domestic automobile manufacturer, the same car in the winter, if there is no active intake grille, the specified time (the specific time manufacturer did not clearly disclose) the car in the idle, urban road conditions and high-speed road conditions under the air conditioning heat exchanger coolant temperature of 56.3 °C, 74.3 °C and 88.6 °C, respectively. After the active intake grille is installed, the coolant temperature is increased by 5.9 °C, 3.2 °C and 1.3 °C, respectively, which will be closer to the normal operating temperature of the coolant of 90 °C.
Since the temperature of the air conditioner is directly determined by the coolant temperature, the average temperature in the car has also increased significantly after the active grille has been installed. Among them, under the winter idling conditions, the temperature inside the car within the specified time is increased from 24.0 °C to 25.6 °C; in the urban road conditions, the temperature is increased from 19.5 °C to 21.8 °C (the temperature in the car is lower than the idle speed in the urban driving condition, because after the vehicle is driven, part of the heat in the car will be taken away by the cold wind from the outside world); and in the high-speed road conditions with large engine load, because the heat generated by the engine itself is already very large, even if there is no active grille, The interior temperature of the car also reached 28.7 °C, and after the addition of the active grille, the temperature inside the car was slightly increased to 29.1 °C. It can be seen that the active grille is indeed conducive to the heating of warm winds in winter. (The data here only means that the active grille is conducive to the warm wind heating in winter, and does not mean that the higher the temperature, the better, the human body's winter comfort room temperature is about 24 ° C, and it is felt that heat can lower the warm air)
In addition to fuel saving and faster supply of warm air in winter, the active grille can also alleviate the low temperature cold protection of the CVT transmission to some extent. Previously, we have explained to you that in order to avoid the CVT gearbox's unique cone wheel + steel belt drive form in the transmission oil temperature is low, the protection performance is not enough when the wear occurs, so the ECU will limit the power output of the engine in the gearbox cold state, and eventually lead to the problem of "dry roaring and not leaving" when the vehicle is opened.
At present, a certain brand of car that uses the most CVT gearbox, in order to increase the heating speed of the CVT gearbox, so the engine cooling system and the CVT transmission cooling system are connected together, trying to use the heat of the engine to heat the gearbox. Although this method can indeed increase the heating rate of the transmission oil when the external ambient temperature is high. However, if it is a cold winter of more than ten degrees below zero, because the cold wind will collide head-on with the water tank, resulting in forced cooling of the coolant in the water tank, if the amount of air is too large, it is possible to cause the coolant temperature to rise for a long time, and even the problem of dragging down the transmission oil heating up in the opposite direction.
Therefore, if the brand can be equipped with an active grille configuration for the vehicle, it can effectively shorten the warm-up time of the engine, increase the temperature of the coolant, and then heat the transmission oil through the cooling system of the engine and the CVT transmission in series, so that the driver can get rid of the "cold protection" as soon as possible.
Through the introduction of this article, I believe that everyone has learned the advantages of this inconspicuous "blind" on the car, which can not only reduce fuel consumption by reducing wind resistance or shortening the speed of the engine heater, but also allow users to blow warm air as soon as possible in the cold winter, and get rid of the cold protection of the CVT gearbox. While saving the cost of use for car owners, it also improves the user experience. Nowadays, under the increasingly stringent situation of global fuel consumption regulations, the active grille is no longer the exclusive luxury brand that pays attention to user experience and the hybrid model with extremely slow heat engine speed, so I believe that it will not be long before everyone can feel the charm of this "blind".