Among PT fuel pumps, PT(G) fuel pump is the most basic fuel pump, and its structure is the most representative. On the basis of PT(G) fuel pump, Cummins Engine Company has developed many types of fuel pumps, such as PT(G)-AFC, PT(G)-EFC, PT(G)-VS and PT(G)-VS-AFC.
PT(G) fuel pump is mainly composed of gear pump, shock absorber, throttle shaft, governor and stop valve.
In order to meet the requirements of supercharged engine, make the fuel supply pressure of fuel pump change with the supercharged pressure of engine, and avoid excessive smoke when the engine is at low speed, Cummins Engine Company developed PT(G)-AFC fuel pump on the basis of PT (G) fuel pump.
PT(G)-EFC fuel pump is based on PT(G) fuel pump, and EFC electronic fuel control valve is added, which is mainly used for various generator sets.
Power devices with large load variation and wide working speed range, such as large trucks, tractors, construction machinery, etc. The fuel pump governor is often required to control the engine at all working speeds, that is, the fuel pump is required to adopt a full range governor. The PT(G)-VS fuel pump developed by adding VS governor (mechanical centrifugal governor) to the basic PT (G) fuel pump is the fuel pump that meets this requirement. In order to control the emission and smoke when the engine working conditions change, an AFC device can be added to the PT(G)-VS fuel pump to form the PT(G)-VS-AFC fuel pump. The unique PT fuel system applied in 1954 is a patent of Cummins. These include:
P- refers to the fuel pressure output by PT fuel pump.
T- refers to the effective time for the fuel injector to allow fuel to flow into the oil cup.
Basic principle of PT fuel system;
PT fuel pump adjusts the appropriate fuel pressure (P) according to the different working conditions of the engine, and it flows into the oil cup of the injector within the effective time (T) determined by the injector under this working condition. In this way, the amount of circulating oil (Q) flowing into the oil cup depends on the fuel pressure (P) and the flow time (T), that is, Q ∝ P * T. Because the metering hole of the injector is unchanged, it is called PT fuel system.
Step time control-step time control