High-pressure fuel pump (HPF): what it is, types, features

The high-pressure fuel pump (HPF) is an important element of the supply of gasoline and diesel engines. It supplies fuel to the injectors of the engine strictly at a certain moment and extremely accurately dose it. Let's consider the main features and types of high-pressure fuel pumps.

Features of the fuel pump

At first, the pump that creates high pressure was installed only in diesel engines. In gasoline engines, the high-pressure fuel pump (HPP) was used in systems with direct injection, because it requires the correct pressure and high accuracy of fuel delivery in time.

The high-pressure pump has a complex design. The main working elements are the piston and the sleeve. When the piston moves in the sleeve, high pressure is created. These two parts must be very precisely matched to ensure a complete seal. The movement of the piston forces fuel into the engine system.

There are other elements involved in the design of a high-pressure fuel pump (HPF):

• A centrifugal clutch controls the flow of fuel at a certain point.
• All-mode regulator of the fuel system of the machine precisely determines what volume of fuel-air mixture is required.
• The electronically controlled high-pressure fuel pump (HPF) is synchronized with sensors that determine when fuel should be delivered.

All of these components operate simultaneously and harmoniously. This allows the engine to run productively.

The high-pressure fuel pump (HPF) is located under the hood near or on the engine. A low-powered low-pressure fuel pump is connected to it. The peculiarity of the operation of the high-pressure fuel pump (HPF) is that not the entire fuel-air mixture enters the injectors, but only certain doses. Excess fuel is removed through the drain valve and flows back into the system. The fuel injector works with increased loads and is sensitive to fuel quality. The fuel must be free of water impurities and various abrasive particles.

Types of fuel injectors

According to the type of piston drive, the high-pressure fuel pump is of three types:

• Mechanical.
• Pneumatic.
• Hydraulic.

Mechanical systems are rarely used, as they have a low level of safety. Pneumatic and hydraulic fuel pumps are installed in passenger cars.

Types of high-pressure fuel pumps (HPF) depending on the design:

• Multi-plunger fuel injectors are connected to the machine's electronic control unit and sensors. Thanks to this, the fuel delivery torque is accurately calculated according to the position of the gas pedal, engine crankshaft speed and other indicators. This system stabilizes the fuel combustion process, reduces the amplitude of engine idling fluctuations and reduces fuel consumption.
• High-pressure distribution pumps are compact. They have high fuel delivery accuracy. However, the plungers wear out quickly.
• Trunk injection pumps use the Common Rail fuel delivery system. Before the fuel arrives at the injector, it accumulates in a special section of the system and is under high pressure. Thanks to this, the fuel injection time is maximally shortened and occurs instantly as soon as the system detects the right moment with the help of sensors. The fuel is delivered in small droplets. This system provides conditions for fuel to burn more completely, increasing efficiency.
• In-line fuel injectors are now installed only in trucks. The system is compatible with lower quality fuel.

If high-pressure fuel pumps (HPF) are operated correctly, they last a long time. It is necessary to use fuel suitable for the pump model, perform timely maintenance and use quality lubricants.