How do diesel motors work

Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Under the Hood. Types of Engines. The diesel engine was invented in by Rudolf Diesel who then patented his new invention in Auto Fuel Economy Does a diesel engine equal fuel cost savings? Cite This! Print Citation. Try Our Crossword Puzzle! What Is the Missing Number? Diesel exhaust filler: This port is for filling the diesel exhaust fluid tank.

Diesel exhaust fluid DEF tank: This tank holds diesel exhaust fluid, an aqueous urea solution, which is injected into the exhaust stream during selective catalytic reduction. Electronic control module ECM : The ECM controls the fuel mixture, ignition timing, and emissions system; monitors the operation of the vehicle; safeguards the engine from abuse; and detects and troubleshoots problems.

Fuel filler: A nozzle from a fuel dispenser attaches to the receptacle on the vehicle to fill the tank. Fuel line: A metal tube or flexible hose or a combination of these transfers fuel from the tank to the engine's fuel injection system.

The walls of a diesel engine block are normally far thicker than a block designed for a petrol engine, and they have more bracing webs to provide extra strength and to absorb stresses. Apart from being stronger, the heavy-duty block can also reduce noise more effectively.

Pistons, connecting rods , crankshafts and bearing caps have to be made stronger than their petrol engine counterparts. The cylinder head design has to be very different because of the fuel injectors and also because of the shape of its combustion and swirl chambers. For any internal combustion engine to operate smoothly and efficiently, the fuel and air need to be properly mixed. The problems of mixing fuel and air are particularly great in a diesel engine, where the air and fuel are introduced at different times during the cycle and have to be mixed inside the cylinders.

There are two main approaches direct injection and indirect injection. Traditionally, indirect injection has been used because this is the simplest way of introducing turbulence so that the injected fuel spray mixes well with the highly compressed air in the combustion chamber.

In an indirect injection engine there is a small spiral swirl chamber also called a pre-combustion chamber into which the injector squirts the fuel before it reaches the main combustion chamber itself. The swirl chamber creates turbulence in the fuel so that it mixes better with the air in the combustion chamber.

The drawback with this system is that the swirl chamber effectively becomes part of the combustion chamber. This means that the combustion chamber as a whole is irregularly shaped, causing combustion problems and hampering efficiency.

A direct injection engine does not have a swirl chamber into which the fuel is injected - the fuel goes straight into the combustion chamber instead. Engineers have to pay very careful attention to the design of the combustion chamber in the piston crown to ensure that it creates enough turbulence. A diesel engine is not throttled like a petrol engine, so the amount of air sucked in at any particular engine speed is always the same.

Engine speed is regulated purely by the amount of fuel squirted into the combustion chamber - with more fuel in the chamber, combustion is fiercer and more power is produced. The accelerator pedal is connected to the metering unit of the engine's injection system rather than to the throttle butterfly as with a petrol engine. The engine then only has to use a small amount of fuel before it comes to a halt. In fact, diesel engines come to rest more quickly than petrol engines because the much higher compression has a greater slowing-down effect on the engine.

As with petrol engines, diesel engines are started by being turned with an electric motor , which begins the compression-ignition cycle. When cold, however, diesel engines are difficult to start, simply because.