fuel pump, also known as high-pressure pump, is an extremely important part of an engine fuel system, the fuel pressure and provide an appropriate fuel source for the fuel system, so that efficient operation.
1. Structure fuel pump
Usually the main fuel injection pump of the camshaft, the roller body, the plunger and plunger barrel, a plunger spring, with the ring gear sleeve rotates, the oil valve and the valve compression pipe joint seat and other components.
the cam shaft is a cylindrical rod-like body structure, a number of sets of upper cam, the valve responsible for the drive, the camshaft is equal to the length of the cylinder group. One end of the camshaft drive wheel and the other end is a bearing supporting point.
axis of the roller body is a shaped part, comprising two parts, the top is an adjusting screw screwed into the nut portion and insurance, has a lower end mounted on the needle roller bearing. The roller is the drive element between the cam and the plunger, generally subjected to an axial force, and the roller itself is subjected to lateral thrust.
the plunger and the plunger sleeve is a precision coupling injection pump, the diametrical clearance is only 0.001-0.003mm, if necessary replaced, the replacement of only one pair of the pair, notThey have replaced separately they carefully processed, from each spotting.
2. Classification fuel pump
according to the fuel injection pump can be divided into the overall structure and synthesis of the pump unit pump (overall pump).
1, the single pump
comprising a single pump plunger, and the two sets of major components of the monomer itself, without the pump camshaft, with some even rollers of the drive component. Single pump because it is mounted at a position close to a head is relatively easy, so greatly reducing the length of the high-pressure pipeline, those currently bore power 200mm or more, a plurality of such monomers using a pump on low speed diesel engines.
2. Synthesis of the pump
Synthesis of each of the cylinders in fuel injection pump 1 has a set of elements that the camshaft by the pump body corresponding to the respective cam drive, and a pump in the same column number of coupling member mounting the cylinder plug equivalents.
according to the fuel injection pump can also be divided cylinder row-line manner, distribution type, monomer type and other three categories.
Commonly used injection pump of the diesel engine are: A pump type, B-type pump, P-type pump, VE pumps and the like. The first three genera piston; VE dispensing pump is the pump rotor.
3. The fuel injection pump works
1, and the suction pressure during oil
Suction and pressure oil injection pump to achieve reciprocating movement of the plunger by the plunger jacket. When the plunger is in position beneath the plunger sleeve two hole is opened, the plunger comprising a pump body and an oil chamber communicating passage, the fuel chamber quickly filled with oil. When the top of the cam roller to the roller body, a plunger rise.
to start the upward movement of the plunger from the hole the front end surface of the plunger is blocked until this period is called the pre-lift stroke, here with the movement of the plunger, fuel oil is extruded from the chamber, the flow of oil Road. The plunger upward, sharp rise in oil chamber oil pressure. When the pressure exceeds the spring force of the valve and the upper hydraulic oil, the oil valve is opened on the top, to the fuel injector is pressed into the tubing. At this time, the plunger hole is blocked, the oil pressure in the process. The plunger sleeve into the hole on the end face of the plunger completely blocked supply starting time point referred theory.
to continue upward movement of the plunger, fuel supply has been continued, the process continues until the oil pressure on the plunger so that the helical oblique opening when the plunger back until the sleeve hole, when a hole is opened, high pressure oil from the oil chamber via the longitudinal grooves of the plunger sleeve and the plunger back into the oil return hole of the oil pump body passage. At this time, the hydraulic oil chamber of the barrel decreases rapidly, oil in the valve spring and the oil pressure in the high pressure tubing falling back seat, immediately injector to stop fuel injection. Although this time the plunger still continue upward, but the supply has been terminated.
the plunger is put back in time the plunger hole theory called oblique open end oil. Suction and pressure oil in the process, with the upward movement of the plunger throughout the process, only the middle section of the oil pressure of the process is called an effective stroke of the plunger.
2, fuel adjustment
The fuel injection pump supply is not fixed, is adjusted in the maximum amount of oil (full load) to the fuel supply amount in the range of zero (stop) of of the diesel engine to meet the changing requirements of the load. By the toothed rod, the rotation of the injection pump piston sleeve so that all achieved while rotating the oil supply amount regulating.
When the plunger is rotated, the start time of oil change, the final fuelingA time, due to changes in the hypotenuse of the plunger sets back the plunger hole location and change. With a different angle of rotation of the plunger, the effective stroke of the plunger is different, and therefore the amount of fuel supply is also changed.
is not greater fuel position of the plunger angle of rotation, the end face of the plunger to the open Zhu greater oblique hole from the back of the plug sleeve, the greater the amount of fuel supply; if column the plug rotation angle is small, the fuel cut start earlier, the amount of oil is small.
When parking the diesel engine fuel cut, for this purpose, the longitudinal grooves on the plunger opposite the plunger can be put to the oil return hole. In this case, the entire stroke of the plunger, the plunger sleeve through the longitudinal grooves have fuel, oil return passage back into the hole, there is no oil pressure process, so that the oil supply amount is zero.
When the plunger is rotated, the end point by changing the amount of oil supply amount to adjust the timing, this method is called the end of the oil supply adjusting method. Further, in order to get the other method of adjusting a position oblique to change the plunger.
injection pumps for diesel engines is ldquo; heart rdquo ;, fuel pump problems lead directly to engine working properly, so the fuel pump must be carried out routine maintenance and upkeep, and needs special attention in the choice of fuel quality the amount.