In search of a way to improve the system of distributed injection engineers have come to the conclusion that it is better to put it straight into the cylinders to optimize the combustion of the fuel, not the intake manifold. This idea has led to the emergence of a new generation of injection systems. History of direct fuel injection
History of direct fuel injection
The inventor of the direct injection system is considered to be the French engineer and car industrialist Leon Levassan. It has installed the first system of this kind on the V8 aircraft engine as a pilot, in order to solve the main problem of self-driving internal combustion engines-violations of the work of the injection at the time of the coup. In 1907, the engine was equipped with the Antoinette VII.
The first direct injection system was developed by Bosch, and it was installed for the first time on cars of the now defunct German brands Goliath and Gutbrod in 1952.
In the seventies fuelled by the fuel crisis, AMC has developed its own direct injection system, which was subsequently equipped with car engines of the same name. The system was called SCFI. Around the same years, Ford produced its own development called ProCo.
In modern car industry, first actively promoted the direct injection of Mitsubishi in 1996
The systems had a number of shortcomings and, after the end of the crisis, interest in direct injection fell. The next wave of development was mid-nineties.
The first actively promoted the direct injection of Mitsubishi in 1996 by installing GDI on a 4G93 Galant four-cylinder engine.
In 2000, it was probably the most famous direct injection system of the Volkswagen-Audi group
Toyota has released its own D4 system to the Japanese domestic market in 1998. In 1999, the Renault IDE system was introduced.
In 2000, the FSI system was introduced (and TFSI in the case of the turbine engine) Volkswagen-Audi group.
In the future, all the world's largest producers presented their systems in one form or another. Direct injection remains a highly relevant topic in view of the interest in saving and stringent environmental standards in modern automobiles.
How direct fuel injection works
Direct injection is a kind of distributed injection used in the most advanced two-stroke and four-stroke internal combustion engines.
The system was most widely distributed in modern diesel engines, as diesel fuel is heavier than petrol, and the problem of combustion optimization is more relevant
In direct injection systems, the fuel is first accumulated in the high pressure line (higher than in the ordinary injection systems) and then by injector injectors are injected directly into the cylinders, that is, into the combustion chamber, where the air is already pummeled.
In direct injection, the fuel-air mixture is intentionally impoverished, which contributes to the efficiency of the engine. At the same time, the problem of reducing capacity is solved by more efficient spraying of fuel. One and the same amount of fuel, depending on the size of the spray, spraying when spraying is different. Small drops, mingle with the air, form a mist in the combustion chamber, in which the flame spreads evenly. The fuel in such spraying is burned almost without the residue, and the combustion products are barely left. In this combustion, the lower dose of the fuel gives the same heat as the high dose for spraying with relatively large drops. The recent study on combustion optimization has continued. The most promising area is the development of the post-secondary injection. The fuel at the post-secondary injection falls into the combustion chamber with very little intervals. This algorithm led to additional optimization of fuel combustion.
The only lack of direct injection is the complexity of the design and the increase in the cost of the components. Producers have to debug the system after the start of sales
Additional savings are achieved through accurate fuel dosing and the opening of nozzles at a specified time. Thanks to computer control, the moment and period of opening of the nozzles may vary rapidly depending on the current engine load.
Direct injection systems focus on the dosage of fuel, so the role of the throttle in the composition of the mix is gradually phased out. In fact, in systems like Valvestronic, VVEL, Nissan, Valvematic, Toyota or Fiat MultiAir, the throttle valve has ceased to be the main instrument regulating the flow of air into the combustion chamber. In addition to the fuel dosing system, the throttle function has been partly taken over by the system of intelligent control of the gas distribution phases.
The direct injection of the gasoline and diesel engine is brought closer together in a constructive way
The use of direct injection of fuel has enabled the introduction of different injection and ignition control programmes to control the operation of the regime in the main modes, usually at three-idling speed (and close to them), traffic under heavy load, and small load movement. In each of these modes, the amount of fuel in the mixture varies. In the mode of deliberately depleted mixture, the greatest efficiency is achieved, in the stoichiometric (i.e. close to the optimum) positive thrust with the average load, in the force-engine develops maximum power. During the driving, the engine control unit constantly changes these modes, depending on the situation.
Direct injection regimes
The lean mode is used when the engine load is minimal, with constant or decreasing speed.
Normal, so-called stoichiometric (optimum) ratio of mass of air and petrol in the combustion chamber required for the successful ignition and combustion of the fuel-air mixture-14.7:1. However, in the situations described above, that is, when engine speed is fast or gradually slowing, it can be done without harming the engine in favor of less fuel. Thus, in the depleted mixture, the amount of air may reach 65 (and sometimes more) by one share of the fuel.
The complex system of direct injection increases the probability of failure. The recall of vehicles equipped with this type of injection
The stoichiometric regime shall be used if the constant load on the engine is steady. In this mode, air and fuel mix in an ideal proportion, which contributes to complete combustion.
The fuel content of the mixture has been slightly exceeded in forced mode. This contributes to the development of maximum capacity, which is useful, for example, for a loaded car in a mountain.
