oil absorption

The oil absorption and pressurization of the fuel injection pump are completed by the reciprocating motion of the plunger in the plunger sleeve. When the plunger is in the low position, two oil holes in the plunger sleeve are opened, and the inner cavity of the plunger sleeve is communicated with the oil passage in the pump body, so that the fuel quickly fills the oil chamber. When the cam pushes the roller of the roller body, the plunger rises. Move upward from the beginning of the plunger until the oil hole is blocked by the upper end face of the plunger. During this time, due to the movement of the plunger, the fuel is squeezed out of the oil chamber and flows to the oil passage. So this promotion is called preview. When the plunger blocks the oil hole, the oil pressing process begins. When the plunger rises, the oil pressure in the oil chamber rises sharply. When the pressure exceeds the spring force and upper limit oil pressure of the oil outlet valve, the oil outlet valve is pushed open, and the fuel is pressed into the oil pipe and sent to the injector.

The moment when the oil inlet hole on the plunger sleeve is completely 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 will continue and the oil pressing process will continue until the spiral inclined surface on the plunger is separated from the oil return hole of the plunger sleeve. When the oil hole is opened, high-pressure oil will flow back from the oil chamber to the oil passage in the pump body through the longitudinal groove on the plunger and the oil return hole on the plunger sleeve. At this time, the oil pressure in the plunger sleeve oil chamber drops rapidly, and the oil outlet valve falls back to the valve seat under the action of the spring and the oil pressure in the high-pressure oil pipe, and the injector immediately stops injecting oil. At this time, although the plunger continues to go up, the oil supply has been terminated. The moment when the oil return hole on the plunger sleeve is opened by the hypotenuse of the plunger is called the theoretical oil supply end point. In the whole process of upward movement of the plunger, only the middle stroke is the oil pressing process, which 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 fuel injection pump must be adjustable within the range of maximum fuel supply (full load) to zero fuel supply (shutdown). The adjustment of fuel supply is realized by rotating all the plungers of the fuel injection pump simultaneously through the rack and rotating sleeve. When the plunger rotates, the start time of oil supply remains unchanged, while the end time of oil supply changes because the oblique side of the plunger changes the position of the oil return hole of the plunger sleeve. With the different rotation angle of the plunger, the effective stroke of the plunger is also different, so the oil supply also changes.

The greater the rotation angle of the plunger to the no-oil-supply position 1, the greater the distance between the upper end face of the plunger and the hypotenuse opening the oil return hole of the plunger sleeve, and the greater the oil supply. If the rotation angle of the plunger is smaller, the oil cut-off starts earlier and the oil supply is less. When the diesel engine stops, the oil must be cut off. Therefore, the longitudinal groove on the plunger can be turned to the oil return hole on the plunger sleeve. At this time, in the whole plunger stroke, the fuel in the plunger sleeve always flows to the oil return channel through the longitudinal groove and the oil return hole, and there is no oil pressure process, so the oil supply is equal to zero. When the plunger rotates, the oil supply is adjusted by changing the time of the oil supply end point. This method is called fuel supply terminal adjustment method.

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

Oil pump is a portable compact pump. An oil pump is proposed, which has a housing made of an aluminum-containing material and a movable molded part arranged in the housing, wherein the movable molded part is at least partially made of a sinterable material containing at least one austenitic iron-based alloy, and the thermal expansion coefficient of the molded part made of the sinterable material is at least 60% of that of the housing.