At present, the plunger type fuel injection pumps made in China are generally divided into I, II, III series and A, B, P, Z series pumps. The following is the introduction of the construction and characteristics of the I pump:
As shown in Fig. 1, the No.1 injection pump is a general structure diagram of the No. I injection pump of a four-cylinder diesel engine. It is composed of four parts: the sub-pump, the fuel quantity control mechanism, the transmission mechanism and the pump body.
As shown in figure 2. and the cylindrical surface of the upper part of the plunger is provided with a left-to-right chute of 45 degrees, a small hole is arranged on the west road, and the small hole is communicated with the small hole in the center of the plunger. the middle of the plunger is provided with a shallow small ring groove, and a small amount of diesel oil can be stored so as to lubricate the friction surface between the plunger and the plunger sleeve. the plunger sleeve is provided with two small holes at the same height, the oil return hole is close to the side of the chute, and the other side is an oil inlet hole. After the plunger sleeve is loaded into the oil pump body, in order to ensure the correct position of the two oil holes, the plunger sleeve is prevented from rotating at the time of operation, the upper part of the plunger sleeve is provided with a small groove, and the positioning screw is used for positioning. the upper part of the plunger sleeve is an oil outlet valve and an oil outlet valve compact seat. the seal between the oil outlet valve seat and the upper end surface of the plunger sleeve is ensured by the machining precision, and the oil outlet valve seat is pressed on the plunger sleeve through a copper gasket through a copper gasket. The tightening torque of the oil outlet valve seat is 50-70N · m, and the washer can be crushed too large.
For the four-cylinder fuel injection pump, there are four regulating forks on the same fuel supply rod, and four adjusting forks are fastened with screws, and the adjusting arm ball heads at the tail end of the plunger of each sub-pump are fastened with screws. When the rod is moved, the four plungers are rotated simultaneously, which changes the fuel supply quantity of each cylinder. When the diesel engine is working, the fuel supply rod is automatically controlled by the governor, and the fuel supply is automatically adjusted according to the change of the external load. If the pump supply is not suitable and need to be adjusted, the locking screw of the adjusting fork can be loosened so that the adjusting fork can move a certain distance on the oil supply rod.
Is mainly composed of a driving gear, a cam shaft and a roller body. the driving gear is driven by the crankshaft through an idle gear. The main function of the transmission mechanism is to push the plunger to move up, while the plunger is in the form of an elastic force against the plunger spring.
The eccentric wheel on the camshaft is used to drive the oil pump through which the drive disk of the governor is fixed to the other end of the camshaft to transmit power to the governor. The two ends of the camshaft are supported by a tapered roller bearing.
The structure of the roller body is shown in figure 3. It consists of roller body, roller and adjustment block. The inner set of rollers has roller bushings, which can be rotated relative to each other, and roller bushing can also be rotated on the roller shaft. The roller body is arranged in the vertical hole of the lower body of the fuel injection pump, the axial long hole is opened on one side of the roller body, and the rear end of the positioning screw extends into the hole. The roller body is mainly to ensure the accuracy of the starting time of fuel supply, and to the multi-cylinder diesel engine, to ensure the consistency of the fuel supply time of each cylinder. The guaranteed position is the height from the lower part of the roller to the plane on the adjustment pad. When the relative position of camshaft gear and crankshaft gear is fixed, the bigger H is, the earlier the plunger closes the intake hole and the earlier the fuel supply begins. The adjustment pad has been adjusted when the fuel injection pump is out of the factory and is not interchangeable at will.
The pump body is divided into two parts, the upper body of the fuel injection pump is used to install the plunger coupling and the oil supply valve coupling, the lower body is used to install the camshaft, the roller body and the oil pump, etc.
An oil channel is arranged in the upper body of the fuel injection pump, and is communicated with an annular oil groove outside the plunger sleeve. and the annular oil groove is communicated with an oil return hole on the plunger sleeve. The low-pressure oil supplied by the fuel transfer pump enters the oil passage through the oil inlet pipe joint. The diesel pressure in the oil channel is controlled by the oil return valve installed in the oil return pipe joint, and is generally required to be in the range of 5 ~ 10KPA. The oil pressure is too low, and when the plunger is down, the diesel oil can not quickly enter the upper oil chamber of the plunger through the oil inlet hole. When the amount of oil is too large to increase the oil pressure, the excess diesel will top the oil return valve to flow into the diesel fine filter.
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