Bosch Unit Pump

1.Product Introduction

The Bosch unit pump, also known as a unit injector or a pump/injector, is a type of fuel injection system commonly used in diesel engines. It combines the functions of both a fuel pump and an injector into a single unit, hence the name “unit pump.” This design allows for more precise control of fuel injection timing and quantity.

The Bosch unit pump operates by using a camshaft-driven plunger pump integrated with an electronically controlled injector. Here’s a general overview of how it works:

1. Fuel Pumping: The unit pump draws fuel from the fuel tank and pressurizes it to a high level, typically in the range of 1,000 to 2,000 bar (14,500 to 29,000 psi). This high-pressure fuel is supplied to the injector portion of the unit pump.
2. Injection Timing and Quantity Control: The injector part of the unit pump is responsible for injecting precise amounts of fuel into the engine’s combustion chambers at the correct timing. This is achieved by electronically controlling the opening and closing of the injector needle, which is actuated by the high-pressure fuel supplied by the pump.
3. High Pressure Accumulation: The unit pump design incorporates a high-pressure accumulator, which helps maintain a constant pressure at the injector for consistent fuel delivery. The accumulator stores excess fuel pressure and ensures that the injector receives fuel at the desired pressure, even during rapid injection events.