The Pumping Process of A Type Fuel Injection Pump in Diesel Engines

The fuel injection pump assembly is usually composed of components such as the fuel injection pump and speed controller installed together as a whole. Among them, the governor is a component that can guarantee the low-speed operation of the diesel engine and limit the maximum speed, and ensure that there is a certain relationship between the injection amount and the speed.

The A-type fuel injection pump body of the diesel engine is an integral type, made of aluminum alloy hard mold casting. Its structure is compact, small in size, and lightweight. There is a window on the side of the pump body, and the bottom is closed with a cover plate. Both the side cover and the bottom cover are fixed with bolts, making the disassembly, adjustment, and maintenance of the fuel injection pump extremely convenient.

The process of oil inlet, pressure, and return of the fuel injection pump is as follows:

1. Oil inlet process: When the plunger moves from the bottom dead center to below the oil inlet hole, the fuel fills the pump chamber under vacuum suction and pressure from the fuel transfer pump.

2. Oil pressure process: When the plunger moves up from the bottom dead center to close the oil inlet hole, the fuel pressure in the pump oil chamber will suddenly increase, and the oil outlet valve will be pushed open to inject high-pressure oil into the high-pressure oil pipe.

3. Oil return process: When the plunger moves up to the spiral groove line or inclined groove line higher than the lower edge of the oil inlet hole, high-pressure oil flows back to the low-pressure oil chamber at high speed through the straight groove or central hole on the plunger. Due to the sharp drop in oil pressure inside the pump chamber, the oil outlet quickly returns to its original position under the action of the spring and residual pressure, and the oil pump stops supplying oil. The plunger continues to rise until the top dead center, which is a return oil process.

4. During the full upward movement of the plunger, h includes the preparatory stroke, the pressure reducing belt stroke, the effective stroke, and the remaining stroke.

Plunger preparatory stroke h1: The distance traveled by the plunger when it rises from the bottom dead center to its upper end face and completely closes the oil inlet hole.

Plunger pressure reducing belt stroke h2: The distance the plunger moves from the end of the preparatory stroke to the opening of the oil outlet valve is called the pressure reducing belt stroke.

The effective stroke of the plunger h3: The distance that the plunger moves from the opening of the oil outlet valve to the opening of the return hole on the spiral or inclined groove of the plunger is called the effective stroke of the plunger.

Remaining stroke h4: The distance the plunger moves from the end of its effective stroke to the top dead center is called the remaining stroke.

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