Direct Injection and Its Advantages

Direct injection is not unfamiliar to Chinese consumers any more. With popularity of the technology, more and more consumers benefit from the technology. However, in China, direct injection is mainly used in turbo charged engines. 

 

The full name of direct injection is engine fuel in cylinder direct injection, DI in short. Direct injection means that fuel injection is carried out directly inside cylinder, which is different from general engines whose injection nozzles are located before inlet valves. 

 

In general gasoline engines, gasoline is injected into inlet manifold, forming gas mixture with air, then entering into cylinder for being burned. Due to the distance between injection nozzle and cylinder, concentration of gas mixture is easily influenced by airflow and on-off of inlet valve. So the theoretical air-fuel ratio is impossible to be realized. Direct injection engines do not have the shortcoming. Through precise control of computer, fuel is directly injected into cylinder in form of high pressure, realizing precise control of mixture between air and fuel and injection timing, making gas mixture be burned more sufficiently. Highly improve energy efficiency, and highly improving energy efficiency.

 

In terms of engines applied with direction injection technology, the working temperature is higher than that of general engines. So the technology has higher requirements for cylinder and cooling system. Nowadays, newly developed direct injection engines adopt aluminum alloy cylinder which has better cooling performance. In addition to ensuring the strength, those engines also use enhanced cooling system. Nevertheless, the engines have higher thermal efficiency. 

 

Direction injection has higher requirements for fuel and manufacturing technique of engines. So in China, only a few of naturally aspired gasoline engines use the technology, such as Honda Accord, Mazda Atenza and Toyota Camery. 

 

Advantages of direct injection: 

1. Direct injection engines have less fuel consumption while high power;

2. Air-fuel ratio can reach to 40:1 (the air-fuel ratio of general engines is only 15:1);

3. Compression ratio can reach as high as 12:1. Compared with general engines, power and torque are improved by 10%.