QX43-020/21-016R Bucher gear pump in stock

QX43-020/21-016R Bucher gear pump in stock

Principles of Machinery

Oil absorption pressure oil

The suction and pressure of the high-pressure oil pump and fuel injection pump are achieved by the reciprocating motion of the plunger in the plunger sleeve. When the plunger is in the lower position, the two oil holes on the plunger sleeve are opened, and the inner cavity of the plunger sleeve is connected to the oil passage in the pump body, quickly filling the oil chamber with fuel. When the cam hits the roller of the roller body, the plunger rises. Move upwards from the plunger until the oil hole is blocked by the upper end face of the plunger. During this period, due to the movement of the plunger, fuel is squeezed out of the oil chamber and flows into the oil passage. So this lift is called the pre trip. When the plunger blocks the oil hole, the oil pressure process begins. The plunger moves upwards, causing a sharp increase in oil pressure in the oil chamber. When the pressure exceeds the spring force of the fuel outlet valve and the upper oil pressure, the fuel outlet valve is pushed out, and the fuel is pressurized into the fuel pipe and sent to the injector.

The moment when the oil inlet hole on the plunger sleeve is blocked by the upper end face of the plunger is called the theoretical oil supply starting point. When the plunger continues to move upward, the oil supply also continues, and the oil pressure process continues until the spiral bevel on the plunger opens the plunger sleeve return hole. When the oil hole is opened, high-pressure oil flows back from the oil chamber through the longitudinal groove on the plunger and the return hole on the plunger sleeve to the oil passage in the pump body. At this time, the oil pressure in the plunger sleeve oil chamber rapidly decreases, and the oil outlet valve falls back to the valve seat under the action of the spring and high-pressure oil pipe, and the injector immediately stops spraying oil. At this point, although the plunger continues to rise, the fuel supply has been terminated. The moment when the oil return hole on the plunger sleeve is opened by the inclined edge of the plunger is called the theoretical oil supply endpoint. During the entire process of upward movement of the plunger, only the middle stroke is the oil pressure process, and this stroke is called the effective stroke of the plunger. Oil quantity regulation

In order to meet the requirements of diesel engine load, the fuel supply of the fuel injection pump must be able to be adjusted within the range of maximum fuel supply (full load) to zero fuel supply (parking). The adjustment of fuel supply is achieved by simultaneously rotating all plungers of the fuel injection pump through the gear rod and rotating sleeve. When the plunger rotates, the start time of oil supply remains unchanged, while the end time of oil supply changes due to the change in the position of the plunger sleeve return hole caused by the inclined edge of the plunger. As the angle of rotation of the plunger varies, the effective stroke of the plunger also varies, resulting in a change in the fuel supply.

The larger the angle of rotation of the plunger for the non oil supply position 1, the greater the distance from the upper end face of the plunger to the inclined edge of the opening plunger sleeve return hole, and the greater the oil supply. If the angle of rotation of the plunger is small, the oil cut-off starts earlier and the oil supply is also small. When the diesel engine is stopped, the fuel must be cut off. To do this, the longitudinal groove on the plunger can be turned to face the oil return hole on the plunger sleeve. At this point, throughout the entire plunger stroke, the fuel inside the plunger sleeve flows back to the oil passage through the longitudinal groove and return hole, without any oil pressure process, so the fuel supply is equal to zero. When the plunger rotates, the method of adjusting the fuel supply by changing the timing of the fuel supply endpoint is called the fuel supply endpoint adjustment method.

The fuel supply of the oil pump should meet the needs of the diesel engine under various working conditions. According to the requirements of the diesel engine, the oil pump should ensure that the fuel supply start time of each cylinder is the same, that is, the fuel supply advance angle * of each cylinder. It should also ensure that the fuel supply duration is the same, and the fuel supply should start quickly and stop quickly to avoid dripping. Depending on the form of the combustion chamber and the method of forming the mixture, the fuel pump must provide fuel with sufficient pressure to the injector to ensure good atomization quality.

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