The development of China’s automobile industry is getting faster and faster. Private cars have entered every household in china. Therefore, people’s requirements for cars are constantly increasing, and the performance of cars is the focus of people’s attention. This paper mainly analyzes the influence of different openings of active air intake grille (AGS) on the performance of the whole vehicle in detail through qualitative and quantitative analysis methods. The active air intake grille can effectively reduce the heating time and greatly reduce fuel consumption in low temperature conditions; when the car is driving at high speed, the use of active air intake grille can effectively reduce the wind resistance of the car and improve the power performance.
Even if the air conditioner is in cooling function, the active air intake grille can be controlled to be at an appropriate opening to reduce wind resistance. In addition, the active air intake grille can also effectively improve the heating performance of the air conditioner. Through the optimization of the control strategy, the active air intake grille can effectively improve the economy of the whole vehicle, thereby achieving the purpose of improving the power of the car.
Keywords: automobile; active air intake grille; research;
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Introduction: As the main door of the car, the air intake grille is mainly used to draw air into the front of the car and dissipate the heat of the engine cooling system. The air intake grilles of different manufacturers are the most important factor in determining the front end. At present, the air intake grilles of most models on the market are fully closed and fully opened, and external cooling air can enter and leave the front of the vehicle through the air intake grille at any time. This will increase the time required for the engine to reach the optimal temperature range when the car is cold started. This will increase the wear of the engine at low temperatures, which is not conducive to meeting national emission and energy efficiency standards.
Advantages of active air intake grilles
In recent years, active air intake grilles have become a growing fuel economy technology in the automotive industry. The front grille is appropriately adjusted according to driving conditions and the measured values of engine oil temperature, water temperature, intake temperature, air conditioning system status and other parameter information. AGS is used to reduce heating time and reduce fuel consumption at low temperatures. AGS is used to reduce wind resistance when driving at high speeds to improve vehicle power, and when the air conditioner is in cooling mode, the opening of AGS is adjusted accordingly to reduce wind resistance.
In addition, AGS can significantly improve the thermal efficiency of the air conditioner. The intelligent air intake grille changes the air resistance by changing the amount of air in the vehicle, which in turn affects the cooling effect, air resistance and radiant heat of the engine and the comfort of the vehicle. Vehicle.
As the country has proposed new standards for automobile fuel economy, many automakers have recognized the importance of AGS in reducing fuel economy. After extensive research and development conducted by AGS, its use will become commonplace in the future. Active air intake grilles are relatively cheap, have obvious fuel economy, and are widely used in the European and North American automobile markets.
By intelligently controlling the opening of the front air intake while driving, the purpose of controlling the amount of cooling air entering the engine room, reducing the internal circulation resistance while driving, and improving the fuel economy of the vehicle is achieved. At the same time, the active air intake grille system can reduce emissions during engine warm-up and improve the engine efficiency of the vehicle. It has been used in overseas mid-to-high-end models, while the use of domestic independent brands is still in a blank stage.
Reduction of aerodynamic drag
AGS mainly improves the aerodynamic characteristics of the vehicle by controlling the flow rate of cooling air. The design function of the cooling system is as follows: even under the worst driving conditions, it must provide sufficient cooling capacity to cool the engine. Therefore, under all other driving conditions, especially on the road, too much cooling air will flow, resulting in drag. When sailing, the radiator grille can be closed to reduce wind resistance and reduce fuel consumption and carbon dioxide emissions.
Cold start and warm-up performance optimization
In recent years, AGS has proposed cold start optimization and preheating, which has attracted increasing attention from automakers, such as improved engine preheating and heat storage capacity in the cabin after the engine is turned off. By shortening the preheating phase, the engine heats up faster and emits less carbon dioxide. It can also melt the windshield and keep the cabin warm faster. The AGS system is an important part of the concept of thermoacoustic engine compartment packaging.
Optimizing vehicle thermal performance
The directionality of the AGS baffle reduces turbulence in the air entering the front of the vehicle and directs air to the radiator, which can increase radiator ventilation and improve efficiency. Completely deactivating AGS, especially in cold weather, while maintaining maximum engine temperature, reduces engine heat generation and improves engine efficiency by reducing airflow through the engine compartment.
Design method of active air intake grille
Closed blades achieve minimum air leakage and optimize driving resistance
When the blades are closed, the cooling airflow is blocked, thereby reducing air resistance. This can be achieved by placing a condensation point forward of the wind to control the air flow around the vehicle instead of cooling the engine components and the cabin. The blade itself and the components around it should have the best possible density. Used with an AGS connected to the cooler air intake. During the AGS design phase, the location of the air intake in the vehicle needs to take into account the possibility of collision and the low drag of the pedestrian module. The inlet of the two-stage injection mold can meet the above design requirements. In order to achieve the aerodynamic goals of the vehicle manufacturer in the vehicle, the requirements for minimum air leakage, packaging space, temperature and other requirements must be considered.
Rapid design method for air leakage
A preliminary estimate of the expected air leakage of the AGS module can be made in the early stages of AGS design. This calculation uses the static final element method and the forces applied on the blade are the same as at the second assumed vehicle speed. If the blade is deformed, the air gap caused by the wind load can be measured, which can be used to calculate the leakage mass flow when the blade is closed. The additional leakage when the blade is closed is caused by the required distance and is independent of the wind speed. The extent of the leakage can be determined by calculating the flow rate of the closed and open wings.
The influence of the blade opening angle on the airflow
When the blade is open, the adverse effect on the AGS cooling airflow must be minimized. The installation of AGS using the most common and economical form of rotating blades will gradually reduce the previously acceptable opening area. Components that block the airflow can be scaled down or optimized to reduce adverse effects.
Compact design of drive motor
As a drive device for rotating the blades and transmitting the driving force, the drive motor needs to be compact and have high torque so that the system can work properly under harsh conditions such as glaze and mud. AGS systems can choose between different drives: In the past, passive systems with fixed magnets were used, but they were abandoned due to low aircraft returns. Vacuum actuators are also used in the same application, but due to limited vacuum availability, the necessary piping, tanks, etc. are not competitive. However, the additional power consumption affects fuel consumption, so the drive motor must be designed with low energy consumption.
Next-generation drive motor technology
Despite the increase in performance and all other requirements, the inevitable trend is to replace the first-generation DC motors and the second-generation stepper motors with brushless motors. The disadvantage of stepper motors is that power consumption and load are independent of each other. This disadvantage is solved in the next-generation BLDC products, and its effect varies with the load.
Conclusion
Nowadays, more and more automakers are adopting AGS to improve aerodynamics and fuel economy, and they are becoming more and more aware of the additional benefits provided by AGS. In the future, the use of AGS will be expanded to include hybrid vehicles with gasoline and diesel engines and electric vehicles. The use of AGS can not only improve aerodynamic efficiency, but also control the cooling process of the battery. The next step is to combine AGS with other insulating components in the engine to improve fuel economy.
