Piston pump oil bodies, including the two sets of precision coupling: plunger (plunger) + plunger sleeve (barrel) constitute Plunger (plunger and barrel assembly) (Figure 5-11), the oil valve (delivery valve ) and the oil valve seat (delivery valve seat) constitute the outlet valve pieces (delivery valve assembly
Plunger and plunger sleeve are a pair of precision coupling, can not be exchanged by the pair, after grinding, requires high precision and finish and good wear resistance, the radial clearance was 0.002 ~ 0.003mm
Cut surface of a cylindrical piston head chute, and through the radial hole, the top of the axial hole and connected, its purpose is to change the cycle of fuel supply; plunger wear a system, a forward, back hole, both with the pump Low oil on the body lumen, the plunger into the pump upper body suit, the application of positioning screw positioning.
The location of the plunger head chute different ways to change the fuel supply are also different.
Outlet valve and the oil valve seat is also a pair of precision coupling, paired grinding are not interchangeable, with the gap of its 0.01mm.
Outlet valve is a one-way valve, under pressure in the spring, the upper conical valve seat surface and close match, its role in the suspension, it will be the top high-pressure plunger cavity with insulated tubing, pressure tubing to prevent the oil back into the fuel pump inside the.
The lower part of the valve was cross sections, both driven, but also by diesel. A conical valve under a small cylindrical surface, known as the decompression zone, its role is to end in the oil supply to high-pressure hydraulic tubing declined rapidly, to avoid the holes produced drip phenomenon. When the ring into the valve seat quickly when the volume is increased to above, the pressure decreases rapidly, Minting quickly.
Work, the fuel injection pump cam on the cam and plunger under the action of the spring, forcing the plunger for the upper and lower reciprocating motion, thus completing the task of pumping the oil, pump oil can be divided into three phases.
Into the oil process
When the cam bumps turn over, the role of force in the spring, the plunger moves downward, the plunger upper space (known as the pumping chamber) of vacuum created when the plunger on the end to put on the progress of the plunger hole opened, filled with the oil channel in the upper body pump diesel into the pumping chamber by the hole, the plunger movement to the next stop point, feed the end.
Oil process
When the camshaft to the cam roller from the top of the bulge body, the plunger spring is compressed, the plunger upward, fuel pressure, part of the upper body fuel injection pump oil through hole flow back into the cavity. When the plunger cover the top hole of the upper edge of the sleeve upward mobility, because the plunger and the sleeve with a small gap (0.0015-0.0025mm) to the oil pump plunger at the top of a sealed chamber into the oil chamber, column Cyprus continues to rise, the hydraulic pump oil chamber increased rapidly, pumping pressure> the valve spring force + high pressure oil remaining pressure, open the outlet valve, high pressure diesel fuel through a valve into the high-pressure pipeline, through the injector injected into the combustion chamber.
Back to oil process
Plunger up oil, when the plunger up to the chute (suspension side) and the sleeve on the back hole connected, the pump oil chamber low-pressure oil line will be in the head with the plunger hole and radial holes and the skewed communications, oil pressure suddenly dropped, the valve spring force role in the rapidly closing, stop the oil supply. Since then even up the plunger, when the cam bumps turn over, under the action of the spring, plunger it down. At this time began the next cycle.
Conclusion: By the above discussion, the following conclusions
① The total stroke reciprocating piston L is constant, the decision by the cam lift.
② plunger fuel supply amount per cycle depends on oil trip trip from camshaft control of oil is variable.
③ start time does not change oil change oil change schedule.
④ Turn the end of the plunger may be time to change the oil, thus changing the fuel supply.
3. Domestic Series Piston Pump
Domestic Series Piston mainly A, B, P, Z and the Ⅰ, Ⅱ, Ⅲ number series. Series is based on single-cylinder diesel engine power range of different requirements on the fuel supply to the plunger stroke, the pump cylinder center distance and structural type, based on each with different size piston diameter accompanied by, the composition of several species in a working cycle ranging from the fuel pump inside the fuel supply to meet the needs of a variety of diesel engines.
Domestic series fuel injection pump working principle and structure of the same type to A-type pump as an example describes the construction of Injection Pump and principle. Piston consists of four major components: Cylinder, fuel adjustment mechanism, drive mechanism and pump