There are two main types of distributed fuel injection pumps: axial compression (VE-dispensing pumps from Bosch, Germany) and radial compression (DPA dispensing pumps from CAV, UK).
Currently, the single-piston VE distribution pump occupies an absolute share of high-speed diesel engines for vehicles.
Compared with the plunger type fuel injection pump, the distributed fuel injection pump has the following characteristics:
1) The distribution pump has a compact structure, a small number of parts, a small volume, and a light weight. The governor and the automatic advancement angle of the fuel supply angle are all installed in the pump body.
2) The distribution pump cam has a small lift, which is beneficial to meet the requirements of high-speed diesel engines.
3) Only one pair of plunger couples is needed, so it is easy to ensure the uniformity of oil supply in each cylinder and the consistency of oil supply timing.
4) The moving parts of the distribution pump are lubricated and cooled by the diesel in the pump body. Therefore, the cleanliness of the diesel oil is very high. When the engine is working under heavy load for a long time, the diesel temperature is high and the plunger is easy to bite.
5) For the multi-cylinder machine, the camshaft of the oil pump rotates one revolution, the plunger reciprocates several times, the linear speed is high, and the plunger is easy to bite. In short, the distributed fuel injection pump has high requirements on the quality of diesel fuel, and no water is allowed.
First, VE type distribution pump structure
1. Composition: As shown in Figure 5-24, the VE type distribution pump consists of a drive mechanism, a two-stage slide type oil pump, a high-pressure distribution pump head and an electromagnetic oil-disconnect valve. Mechanical governor and hydraulic oil supply The automatic advance angle advanceer is also installed in the pump body. The camshaft end faces of the drive shaft are respectively connected to the coupling by the convex keys, and the inner hole of the stationary roller frame serves as a bearing hole of the coupling. There are four rollers (four cylinders) on the roller frame, and the pin shaft is connected with the roller frame.
2. When the drive shaft rotates, the coupling and the end cam disc rotate in the same direction. Since the end cam disc is pressed against the roller frame by the plunger return spring, the end cam forces the roller to rotate and makes the end cam disc act as the shaft. Move back and forth in a straight line. The end cam disc is embedded in the opening slot of the dispensing plunger disc by the driving pin, and the plunger resets the plunger against the end cam disc, thereby driving the dispensing plunger to rotate, and the cam profile causes the dispensing plunger to While rotating, it also makes a reciprocating linear motion. The distribution plunger has an axial center oil hole.
3, radial through the drain hole
4, four oil inlet tanks (four cylinder machine), one fuel distribution hole
5. The pressure on the outer circumference balances the undercutting groove. The center oil hole is connected to the drain hole
The plunger sleeve has an oil inlet and four distribution oil passages (four cylinder machine)