Automotive Temperature Control and Dynamics

The amount of time it takes to inject a specific amount of fuel, controlled by injector opening size and pressure difference between intake manifold and fuel supply.

A type of fuel injector where an electromagnetic coil opens and closes the fuel flow.

The small, movable part in a solenoid injector that controls fuel flow.

The opening in a fuel injector that sprays fuel into the engine.

The electronic control unit that manages engine functions, including fuel injection timing.

A fuel injection system where injectors spray fuel directly into the engine's intake ports, near the intake valves.

The process of injecting fuel into the engine during cold engine conditions to help it start and warm up.

The timing of fuel injection, controlled by the ECU to optimize engine performance.

Direct injection allows for precise control of fuel distribution within the cylinder by mixing fuel with only a portion of air, creating a stratified fuel-air mixture.

Direct injection minimizes the delay between fuel injection and combustion, enabling faster and more precise mixture preparation for varying engine demands.

Direct injection allows for leaner overall operation while maintaining a rich mixture near the spark plug, improving fuel efficiency.

Fuel vaporization within the cylinder cools the air charge, allowing for higher compression ratios in direct injection engines.

Direct injection engines have a higher volumetric efficiency, meaning they can induct more air, leading to increased torque.

Direct injection offers tighter control of fuel mixture, especially in stratified lean operation, leading to improved fuel consumption.

Direct injection systems cost more due to the higher injection pressure required.

Direct injection engines can have a higher tendency to produce particulate matter (PM) in the cylinder.

In direct injection (DI) engines, fuel is injected directly into the combustion chamber, unlike port injection (MPI) where fuel is injected into the intake manifold.

DI engines need higher fuel pressure (up to 200 bar) compared to MPI engines (typically around 5 bar), causing a shorter injection time for fuel delivery.

DI engines operate with a shorter injection time, only needing half a crankshaft revolution for a homogeneous mixture, compared to two revolutions in MPI.

Multi-hole injectors in DI engines ensure a stable spray angle, facilitating better fuel evaporation and mixture preparation.

DI engines can produce higher particulate emissions compared to modern standards due to fuel injection directly into the combustion chamber.

To reduce particulate emissions in DI engines, particulate filters are employed to trap and remove soot particles from the exhaust.

DI engines require a high-pressure fuel delivery system to quickly deliver fuel to the injectors, consisting of a high-pressure pump, fuel rail, sensor, and pressure-control valve.

In a demand-controlled DI fuel delivery system, the high-pressure pump delivers only the exact amount of fuel needed, eliminating excess fuel and improving fuel efficiency.

A combustion process where fuel and air are premixed before ignition, resulting in lower temperatures and reduced emissions. Often occurs with lean mixtures, where air is in excess compared to fuel.

A diagram that visualizes the relationship between local equivalence ratio (fuel to air ratio) and local temperature during combustion. It helps to understand the formation of soot and NOx emissions.

A common combustion process where fuel and air mix inside the cylinder, leading to higher temperatures and significant soot and NOx emissions.

Exhaust gas recirculation (EGR) refers to diverting a portion of exhaust gases back into the intake system, which helps lower combustion temperatures and NOx emissions.

A combustion strategy where ignition occurs after a considerable delay following fuel injection, allowing for a more controlled and homogeneous burn. This technique is often used in LTC engines.

The time it takes for injected fuel to ignite in a diesel engine.

A measure of how easily a diesel fuel ignites. Higher cetane numbers mean easier ignition, leading to smoother combustion.

A type of fuel derived from plants or animal fats, often blended with regular diesel.

The rate at which fuel burns in an engine, influenced by factors like fuel-air mixing and injection rate.

The process by which fuel and air mix in a diesel engine, affecting the temperature and efficiency of combustion

The model that explains how combustion occurs in a diesel engine, taking into account fuel spray, flame development, and heat release.

The process of introducing fuel into the combustion chamber, highly influenced by factors like timing and injection rate.

The rate at which fuel is injected into the combustion chamber, influencing the burning rate and combustion intensity.

In diesel engines, combustion happens due to the high temperature and pressure inside the cylinder when fuel is injected. The fuel mixes with air, and how quickly this happens controls how the fuel burns.

A key difference between diesel (CI) and gasoline (SI) engines is how the fuel and air mix before burning. In diesel, the mixture is uneven and there's no risk of knocking (rapid, uncontrolled burning) like in gasoline engines.

Diesel engines can handle much higher compression ratios (15 to 21) than gasoline engines. This helps them convert fuel into power more efficiently.

Diesel engines are designed to withstand high cylinder pressures (up to 230 bar). This is because 'knocking' is not their limiting factor like in gasoline engines.

The time between when fuel is injected (SOI) and when it starts burning (SOC) is called the 'ignition delay'. For smooth operation, this delay needs to be short and consistent.

The 'cetane number' is a measure of how easily a fuel ignites. Diesel fuels need high cetane numbers to keep the ignition delay short and prevent excessive pressure.

Diesel engines don't use a throttle to control engine power like gasoline engines. Instead, they change the amount of fuel injected into the cylinder per cycle.

If too much fuel is injected in a diesel engine, it can lead to excessive soot formation. This limits the engine's ability to burn fuel efficiently.