Suoraruiskutusta

Suoraruiskutus, in automotive engineering commonly translated as direct fuel injection, is a method of delivering fuel directly into the combustion chamber of an internal combustion engine under high pressure. It contrasts with port or indirect injection, where fuel is introduced into the intake port or a pre-chamber. The Finnish term is used for both gasoline and diesel direct injection systems.

In gasoline engines, suoraruiskutus (gasoline direct injection, GDI) sprays fuel directly into the combustion chamber, allowing precise control of the air–fuel mixture and the possibility of stratified charging at light loads. In diesel engines, direct injection is standard, injecting fuel directly into the cylinder where it auto-ignites under high compression. Modern systems use advanced high-pressure pumps and electronically controlled injectors, often integrated with turbocharging and exhaust aftertreatment.

The main advantages of suoraruiskutus include higher thermal efficiency, improved power and torque, and better fuel economy under certain operating conditions. It also enables flexible combustion strategies and reduced throttling losses. Disadvantages include greater system complexity and cost, stricter tolerances for injectors and fuel pumps, and potential issues such as carbon buildup on intake valves in gasoline engines and higher nitrogen oxide and particulate emissions without proper aftertreatment.

Historically, direct injection has roots in early engine research, with diesel engines adopting it extensively and gasoline direct injection gaining prominence from the late 20th century onward. Today, suoraruiskutus is widely used in modern engines, often in combination with turbocharging, variable valve timing, and particulate and NOx control technologies to meet emissions standards.