Request a Password

Delivery Valves: The Role They Play in Diesel Engines

Posted by Scott Goldfarb on

Diesel engines have two types of diesel delivery valves: intake valves and exhaust valves. Delivery valves move gas and fuel mixtures in and out of the cylinders of a diesel engine. Both types have a vital role to play in keeping your engine working at pique performance levels. Let’s examine the differences between the two valves and how they work to create power and energy in a diesel engine.

Delivery Valve Overview

The intake valve is the diesel fuel valve that opens to allow the fuel and air mixture to flow into the cylinders of the engine. The intake valve then seals, and while the exhaust valve is still also sealed, the fuel and air mixture is compressed, where it reaches extremely high temperatures before combusting and igniting. After the combustion occurs, the exhaust valve opens to allow the exhaust gases to exit the chamber of the cylinder. The exhaust valve then closes when the intake valve opens again to repeat the process.

A valve train arrangement connects a crankshaft and a camshaft of the engine. A geared mechanism (such as a timing chain or timing belt) transfers motion between the crankshaft and the camshaft.

The intake and exhaust valves are situated above the cylinder. As a camshaft rotates, it forces the valves open by pushing them downward into the cylinder. When the camshaft rotates more the springs on the valves bring them back up to a tight, sealed position.

The mere movement of the valves creates energy that is strong enough to move the crankshaft, which in turn creates the energy needed to move a large vehicle at high speeds, or power a large boat through the ocean. There are four cycles the cylinder and valves go through as the piston lowers and rises two times each. Let's dive deeper into the cycles the valves go through to create such power.

The Intake Cycle

The first cycle is the intake cycle. When the intake cylinder piston cycles downward, it draws the fuel and air mixture into the cylinder by creating negative pressure. The intake valve stays open until the piston reaches bottom dead center, which is the lowest point in the cylinder.

The Compression Cycle

The second cycle is the compression cycle, where the intake valve is closed to seal off the cylinder while the piston rises to top dead center, which is the highest position. This movement compresses the fuel and air mixture. The compression serves multiple purposes. It increases the temperature of the fuel and air mixture, which helps the burning to be more efficient. It also creates a higher pressure for the piston when the fuel is ignited.

During the compression cycle, additional fuel is injected through the diesel fuel injection pump situated between the intake valve and the exhaust valve.

The Power Cycle

The third cycle is the power cycle. The injection of the fuel into the compressed fuel and air mixture that was already in the cylinder causes the fuel and air mixture to ignite and explode, and that explosion forces the piston back down to the bottom dead center. The movement of the piston downward from the force of the explosion transfers energy from the chemical energy of the explosion to the movement of the crankshaft the piston is connected to.

The Exhaust Cycle

The fourth cycle is the exhaust cycle, where the piston rises again, but this time with the exhaust valve open. The intake valve is closed, which, combined with the force of the rising piston, forces the exhaust gases out of the exhaust valve and into the exhaust manifold.

When the piston is at the top of the cylinder at the end of the exhaust cycle, the exhaust valve closes again and the intake valve opens again, starting the intake cycle and the process for that cylinder all over again.

An engine with multiple cylinders has the cylinders synched so they are each in a different cycle at a different time, which smoothly powers the engine. An intricate design and the precise electrical timing of ignition signals combine to create the sophisticated sequencing of all the different movements.

If you are in the market, you can find parts for any diesel engine on our website, including delivery valves for sale. Because of the very precise calibration the engine needs in this area, it is best to leave any work done on diesel pump parts to experienced professionals.



Leave a comment

Please note, comments must be approved before they are published


Stay up to date with our best deals by signing up for our email specials.

Weekly Specials
Join Our Newsletter
Save 10% on your next order