The
injection pump is called the "heart" of the diesel generator set,
which shows the importance of the fuel injection pump of the diesel generator
unit. It is the most important component of the diesel fuel supply system. Its
function is to increase the pressure of the diesel generator set and to supply
fuel to the fuel chamber on a regular and quantitative basis according to the
requirements of the working process of the diesel generator set.
The
main structure of the 4, 6, and 12-cylinder fuel injection pump is basically
the same (as shown in FIGS. 1 and 2) except the number of cylinders, and is a
multi-cylinder composite type. It is composed of the fuel injection pump body,
the sub-pump, the transmission mechanism and the oil quantity control
mechanism.
Each
pump mainly consists of oil supply valve tight seat, oil supply valve spring,
oil supply valve couple, plunger coupling, spring upper seat, spring lower
seat, plunger spring, oil quantity control sleeve, adjusting gear, rolling
wheel parts and so on, as shown in figure 3.
Above
illustration:
1-
oil outlet valve tight seat; 2-oil valve spring; 3-oil outlet valve coupling;
4-sleeve positioning nail; 5-lock screw; 6-oil quantity control sleeve;
7-spring upper seat; 8-plunger spring; 9-spring lower seat; Keywords 10- oil
level screw; 11- pump body; 12- adjusting tooth rod; 13- outlet screw; 14- oil
limiting screw; 15- plunger coupling; 16- timing adjusting screw; 17- timing
adjusting nut; 18- adjusting gasket; 19- roller body assembly; 20- Shaft cover
parts; 21- Camshaft.
The
oil supply valve couple part is the relief type oil delivery valve. Plunger
coupling and oil supply valve pair are mutually developed, the user is
absolutely not allowed to replace the single piece in repair, disassembly and
replacement.
The
oil supply principle of the fuel injection pump of the diesel generator set is
shown in Figure 4. When the plunger is in the lower stop position, the two oil
holes on the plunger sleeve are open, the space on the upper part of the
plunger is communicated with the oil channel in the oil pump body, and the
inner cavity of the plunger sleeve is filled with fuel, as shown in Fig. 5a. As
the plunger moves upward, a portion of the fuel is squeezed and poured into the
oil passage, which process continues until the top surface of the plunger
passes over the upper edge of the oil hole, as shown in FIG. 5b.
Since then the
plunger continues to move upward, the fuel pressure in the chamber increases
sharply, the oil delivery valve is opened, and the fuel is pressed into the high
pressure tubing through the tight seat of the oil delivery valve. As the
plunger continues to move up, the fuel pressure of the high pressure tubing and
injector is greatly increased.
When the pressure exceeds the opening pressure
of the injector, the injector needle valve opens itself and the high pressure
fuel begins to be injected into the combustion chamber, as shown in figure 5c.
The plunger feed continues until the screw edge of the plunger reaches the
lower edge of the plunger casing hole, as shown in figure 5d. When the oil hole
of the plunger sleeve is opened, the injector fuel injector stops.
The
high-pressure fuel oil flows back to the low pressure chamber of the pump body
through the oil holes in the plunger's straight grooves and plunger sleeve. As
shown in figure 5e, the space above the plunger and the pressure in the tubing
are reduced, and the oil supply valve falls to the valve seat under the action
of the spring. When the plunger moves downward under the action of the spring,
the space above the plunger in the plunger sleeve is filled with fuel again,
ready for the next working cycle.
The
amount of oil in the injection pump of the diesel generator set depends on the
relative position of the plunger and the plunger sleeve, and rotating the
plunger can control the fuel supply. When adjusting the movement of the tooth
rod, the gear ring and the oil quantity control cylinder drive the plunger to
rotate. If the plunger rotates to the right, the oil supply increases and the
oil supply decreases, as shown in figure 5fg. Once the plunger tank is
connected to the oil hole of the plunger sleeve, stop the oil supply, as shown
in figure 5 h.
A-down
check point, oil filling; b-oil completion, start oil supply; c-oil supply
process; d-oil supply end, start return oil; etop check point, return oil; f-
partial oil supply; g-maximum oil supply; h- stop oil supply.
The
12 cylinder B injection pump used in 12V135 power station diesel engine is also
equipped with a buffer above its front surface. As shown in figure 6, the
buffer consists of a shell, a piston, a spring seat, a fuel regulating screw, a
refueling and discharging screw, and so on.
1-buffer
housing; 2-buffer piston; 3-spring; 4-oil drain plug; 5-adjusting screw;
6-filler plug; 7-connecting rod
During
use, the user should often rotate the screw plug to check to make sure the
buffer is filled with lubricating oil. When the oil pump rack moves along with
the buffer piston through the connecting rod mounted on the top of the rack,
the oil in the upper and lower cavity of the buffer automatically reflows back
through the needle valve hole of the screw, which plays a buffer role and
stabilizes the rotational speed. The position of the adjusting screw shall be
sealed by the factory during the bench test.
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