The mechanical principle of oil pump
Oil suction pressure oil
The oil suction and oil pressure of the injection pump are completed by the reciprocating movement of the plunger in the plunger sleeve. When the plunger is located in the lower position, the two oil holes on the plunger sleeve are opened, and the inner cavity of the plunger sleeve is communicated with the oil passage in the pump body, and the fuel is quickly filled with the oil chamber. When the CAM rests on 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 period of 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 lift is called pretravel. When the plunger blocks the oil hole, the oil pressing process begins. When the plunger goes up, the oil pressure in the oil chamber rises sharply. When the pressure exceeds the spring spring of the oil outlet valve and the upper oil pressure, the oil valve is pushed out, and the fuel is pressed into the oil pipe and sent to the fuel injector.
The time 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 continues, and the oil pressure process continues until the helical bevel on the plunger opens the oil hole. When the oil hole is opened, the high-pressure oil flows from the oil chamber through the longitudinal groove on the plunger and the oil return hole on the plunger sleeve to the oil passage in the pump body. At this time, the oil pressure of the plunger sleeve oil chamber decreases rapidly, the oil outlet valve falls back to the valve seat under the action of oil pressure in the spring and high pressure tubing, and the injector immediately stops spraying oil. At this time, although the plunger continues to rise, the oil supply has been terminated. The moment when the oil return hole on the plunger sleeve is opened by the bevel side of the plunger is called the theoretical oil supply end point. In the whole process of the upward movement of the plunger, only the middle part of the stroke is the oil pressure process, which is called the effective stroke of the plunger.
Fuel control
In order to meet the requirements of the diesel engine load, the fuel supply of the fuel injection pump must be able to adjust within the range of the maximum fuel supply (full load) to the zero fuel supply (stop). The adjustment of the fuel supply is realized by the tooth rod and the rotating sleeve to make all the plungers of the fuel injection pump rotate at the same time. When the plunger rotates, the oil supply start time is unchanged, and the oil supply end time is changed due to the change in the position of the oil return hole of the plunger sleeve on the bevel side of the plunger. With the different Angle of rotation of the plunger, the effective stroke of the plunger is different, and the oil supply is also changed.
The greater the Angle of rotation of the plunger for no oil supply level 1, the greater the distance between the upper end face of the plunger and the hypotenuse of the oil return hole of the open plug sleeve, 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 smaller. When the diesel engine is stopped, the oil must be cut off. For this reason, the longitudinal groove on the plunger can be turned to the oil return hole directly opposite the plunger sleeve. At this time, in the whole plunger stroke, the fuel in the plunger sleeve has been flowing back to the oil channel through the longitudinal groove and the oil return hole, there is no oil pressure process, so the oil supply is equal to zero. When the plunger rotates, the time to change the oil supply end point is used to adjust the oil supply, which is called the oil supply end point adjustment method.
The oil supply of the oil pump should meet the needs of the diesel engine in various working conditions, according to the requirements of the diesel engine, the oil pump should ensure that the oil supply of each cylinder starts at the same time, that is, the oil supply advance Angle is consistent, should also ensure that the oil supply duration is the same, and the oil supply should start quickly, stop the oil quickly and neatly, to avoid dripping. Depending on the form of the combustion chamber and the method of mixture formation, the oil pump must provide fuel with sufficient pressure to the injector to ensure good atomization quality.
Zhuo Meng Shanghai Auto Co., Ltd. is committed to selling MG&MAUXS auto parts welcome to buy.
