All you need to know about this type of motors.
Gasoline engines with direct fuel injection motorists and assessed differently: some consider them an example of technological excellence, others fear it like the plague and ready to abandon them at the stage of choosing a car. Understand the design and find out what is love and hate direct injection.
What’s the difference schemes with direct injection
Gasoline internal combustion engines with direct injection have begun to enter the domestic market in the early 2000’s and has now become an indispensable attribute of any more or less modern car of the middle or upper price segment. In other words, they have long been a reality and will remain so until humanity’s transition to a fundamentally different vehicle, with which now the majority of experts see electric cars.
The main difference from the traditional system of the distributed injection scheme with direct injection is that gasoline it is not the intake manifold, and directly into the cylinders. Thus, the combustion chamber receives not ready air-fuel mixture, and “live” fuel, wherein the mixing is performed in the motor.
Why is it necessary
The question of creation of system of direct injection, the engineers attended to in the second half of the nineteenth century, however, to bring to mass serial production are relatively recent. First, the market received motors family Mitsubishi GDI, and then pulled up, and all the other world-famous brands — Volkswagen, GM, Toyota, Mercedes, BMW, Ford, Peugeot/Citroen, Renault, Mazda and even Hyundai.
The trick is that the scheme with the direct distributed injection allows extremely finely and accurately control the process of mixing and to force the gasoline engine to work on the incredibly poor fuel-air mixture. If the normal engines typically operate at a ratio of gasoline to air in the ratio of 1:14, the motors with direct injection in some modes, leave at 1:20 or even 1:40. It is easy to guess that this allows them to burn much less fuel. The processes of mixture formation in real time and the use of multiple modes increases the power and dynamic performance and improves the sustainability of the power unit.
Manufacturers of these engines lead a very eloquent data: fuel consumption reduced by an average of 20-25%, and thrust and power increase by 10-15%. And all this with a small displacement, use of recycling systems and the post-combustion exhaust according to the strictest environmental regulations and the possibility of use in internal combustion engine multi-stage turbocharging. In short, no motors!
And all anything, Yes the use of direct injection schemes entail extremely high requirements, not only to the design of the power unit, but also to the fuel pump and quality of fuel and lubricants, injectors and electrical, most other vital units of the car.
To achieve a proper education of the mixture by direct injection extremely difficult. For this “brains” of the machine are supplied by several management programs with different cycle and a pile of high-precision sensors. And for the atomization of the fuel charge of a special vortex nozzle working at high pressure, which, in turn, the car is equipped with high-performance fuel pumps, similar to those used in diesel schemes (if conventional pumps develop about 3-4 ATM, these provide 50-130). Of course, the components of such systems must be incredibly technologically advanced and high quality, designed for long service life. The observance of these conditions allows for more effective spraying the fuel, it is better to mix it with air and competently dispose of the mixture at different engine operating conditions.
Being unloaded (for example, in idling), direct injection engine is operating in stratified mode the mixture formation, the mixture is maximally depleted, but remains of sufficient quality and fit for work. In this mode, the throttle valve is widely opened, and the inlet vanes are in the closed condition. The fuel is injected late in the compression stroke in the region of the spark plug, where whirls and flammable. Homogeneous mixing allows you to mix the power required for uniform engine loads and transient conditions. At maximum load open throttle, and the intake channels, and the fuel is still injected during the intake stroke. At the same time, if possible, and burnt with the exhaust gases, which improves environmental performance without compromising the motor.
All of this requires refinement of the geometry of the combustion chamber, increasing the compression ratio to 1:12-14, the use of more complicated and expensive catalyst, high-performance injector with powerful solenoids, and high-performance multi-mode fuel pump.
The pros and cons
The main disadvantage of the system of direct fuel injection is a General decrease of reliability: even during minor failures or breakages of any component of such engine begins to “act up” to stall, to sneeze, not to reach full capacity, light icon on the dashboard and in every possible way to hint the owner.
Another equally important drawback is the cost of this unit is a sophisticated device, requiring special attention and control to all systems, including the system power supply, ignition, release, and electronics.
Sensitivity to fuel quality is another fat minus, which is willing to put up not every car owner. Buying a car with direct injection system, you are guaranteed to start an extremely careful approach to the selection of dressings: filled with cheap fuels, alas, will not succeed. And it’s not that these motors need a special octane — some of them have learned to work even on 92-m gasoline or alcohol, but the contents of low-quality gasoline sulfur, phosphorus, iron and other impurities, impede the normal operation of the internal combustion engine.
Finally, to deter from buying the car with the engine maybe the high cost of spare parts and maintenance. Cheap high-tech parts are not, the requirements to oils, filters and other “consumables” are also on the rise.
But all this pales against the backdrop of the pros:
It is the engines with direct injection are the most technologically advanced, fuel efficient, light and traction. They are ideal for use in busy urban areas (in the mirror modes of the internal combustion engine with direct injection the most economical), in addition, they allow to increase the oil change interval and have extended life due to the reduction of carbon deposits (this is achieved programmatically maximise the efficient burning of the fuel / air mixture). However, all this can only be achieved with extremely careful attention to the car and proper maintenance.
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