Diesel engines have been used for transportation and industrial power for generations due to their durability and efficiency. The injection pump is a vital component of these powerful machines that determines their efficiency, performance, and reliability. However, there are different types of injection pumps in diesel engines, each with unique characteristics that differentiate them from one another.
With advancements in technology, the engineering and manufacturing of injection pumps have evolved. Significant improvements have been made from manually controlled systems to modern electric common rail systems to increase fuel efficiency, control emissions, and enhance engine performance.
So, we will discuss the various types of fuel pumps in diesel engines and how they function. Understanding these components is crucial for diesel enthusiasts, technicians, and anyone who relies on diesel-powered machinery.
Source: shutterstock.com/ Photo Contributor:Â Ivanka Kunianska
What Is an Injection Pump in a Diesel Engine?
It is the central component responsible for precisely delivered fuel that maintains a rhythm or timing. It keeps the engine running as smoothly as possible. This orchestrated fuel delivery is vital for the engine’s operation as it directly impacts the housing's efficiency, emissions, and power output. So, the injection pumps act as the engine's heartbeat that powers the entire system.
By managing the timing and the delivery of the amount of fuel needed to gain the desired power, a diesel fuel injection pump can ensure the engine operates at peak performance. Simultaneously, this simple pump does the job of both the ignition system and the throttle needed in gasoline engines.
However, troubleshooting a gasoline engine can quickly become a tiring task. It involves checking several components, including fuel, compression, and spark, to identify the issue and ensure the engine runs smoothly. Yet, diesel engines do not need an ignition system, making it one less issue to worry about.
How does an injection pump work?
A diesel pump and petrol engine are responsible for utilizing an internal combustion system to power the vehicle. They have a mixture of air and fuel that, once ignited, deliver a force with enough explosive power to ultimately get the wheels on a vehicle moving.
However, the similarity between gasoline-powered and diesel engines ends there, as how the fuel mixture is ignited is vastly different. Unlike a gasoline engine, the diesel engine does not require spark plugs for fuel ignition. This is because, in diesel engines, the fuel is ignited using extremely compressed air provided by the injection pump.
In the ignition phase, pressure remains constant as volume starts to expand. The volume and pressure decrease once the engine is ignited, ultimately powering the car. This phase is also known as the power stroke. However, the volume remains constant at its highest level in the exhaust phase as the cycle begins anew once the air is drawn in for compressing in the first phase.
In order to restrain the amount of diesel fuel and air entering each chamber, some valves serve as limitations for the mixture. This allows maximum fuel efficiency and no wasted material.
Types of Injection Pumps in Diesel Engines
Generally, how injection pumps work depends on the types of injection pump you use, as there are several different kinds. While each fuel pump works differently, they all serve the same purpose: moving fuel through the system and into the combustion chamber.Â
We have the best quality on the market if you need a new or remanufactured fuel injection pump for your diesel engine or another component. Or, if you have any concerns about any diesel engine parts, you can always reach out to us.
So, how many types of fuel pumps are there in the diesel engines? We will cover four types of injection pumps in diesel engines. They are the following ones:
- Distributor (Rotary) fuel injection pump
- Inline-injection (Jerk) fuel injection pump
- Continuous pump
- High-pressure common rail pump
Distributor (Rotary) fuel injection pump
As you might gather from the name, a rotary pump has more of a smaller circular design. These pumps are the earliest forms used in diesel engines and are considered highly durable and sustainable.
The distributor pump’s main feature is its injection system. The pump works when the plunger directs all fuel into each chamber and places it around each pump shaft. Once the pump shaft rotates, the plunger will press the fuel through the chamber to the ignition timing.
Furthermore, this type of pump is controlled electronically by various sensors. This includes:
- An electronic control unit
- An actuator
The control unit is responsible for calculating the optimum levels for the engine’s running condition and sending signals to the actuator. Then, the actuator controls the timing and amount of fuel injected accordingly with the signals it receives from the control unit.
Inline injection (Jerk) fuel pump
Unlike rotary pumps, inline injection pumps have the output lines in a straight line. This type of pump aligns with the engine cylinders in their number of fuel pressure mechanisms. The inline injection pumps are primarily used for medium to large-sized vehicles and construction machinery.
Each cylinder in the engine has a pump and a plunger combination connected to it. Once the diesel fuel enters the pump, one end directs it toward the chamber where combustion occurs, and the other is where the plunger is located.
The plunger moves back and forth, and with this motion, it leaves an opening for the fuel to enter the combustion chamber while moving backward. However, moving forward creates enough force to compress the air in the chamber, creating heat. This heat is kept in a rapidly shrinking space, which drives up pressure and temperature, thus causing ignition almost instantly.
Continuous pump
The continuous pump is the latest type of diesel engine injection pump. It’s likely the most widely used and applied one today due to its durability and efficiency. Generally, you can find this pump applied to direct injection systems.
The continuous pump is the smallest and has the most concise form out of all the pumps we’ll mention. This is because this particular pump has very few functions. Its primary responsibility is to increase fuel pressure stably at high pressure and generate by 30,000 – 40,000 PSI.
Furthermore, this type of pump is also responsible for regulating the timing and volume of sprayed fuel. The pump will suppress the fuel and hold the pressure at the applied limit. The continuous pump works like a water pump with a turbine, even though some kinds only use membranes.
High-pressure common rail pump
A high-pressure common rail pump has a slightly different design from the rotary and inline injection pumps. Based on its unique design, this pump is a system with a high-pressure circuit.
The high-pressure common rail pump is manufactured with revolving pistols, as well as an inlet and one or two outlets. In the design, the outlets are connected to a rail that supplies the pressure to the system. So, unlike the inline or rotary pump, which covers the amount of pressure applied, the rail handles the pressure in the common rail pump, and the ECU takes care of the fuel distribution.
Ultimately, the standard rail pump’s only duty is ensuring maximum fuel pressure so that the fuel can be atomized once the ECU opens the injector.
Source: shutterstock.com/ Photo Contributor:Â Warut Wetsanarut
Conclusion
Injection pumps are vital in a diesel engine's fuel delivery system, ensuring a smooth ride, engine power, and efficiency. These pumps are responsible for precisely delivering, metering, and timing the diesel fuel into the engine’s combustion chambers.
Choosing the right pump out of the various types of injection pumps in diesel engines may be of even higher importance. This decision may influence your engine's power output, fuel efficiency, emissions, and longevity.
While technology advances, common rail and continuous systems may have become increasingly popular in the modern world due to their control and precision. However, traditional designs such as rotary and inline pumps continue to serve effectively, with simplicity and reliability as the highest values.
