2.1
Gear system and valve mechanism of Weichai Power Generation Diesel Engine
The valve mechanism
comprises camshaft gear, camshaft, tappet, push rod and valve train, and it
adopts a structure of overhead valve and underneath camshaft.
Camshaft gear1 is driven
by crankshaft gear 6 through idle gear 2, and crankshaft gear 6 also drive fuel
injection pump 3 through idle gear 2.The gears should be assembled according to
the paired engagement marks. Each gear is marked with “.”, and the gears must
be assembled with “.” marks aligned to ensure that the valve timing and fuel
supply time are correct, as shown in Figure 2-1.
Driven by the camshaft
gear, the camshaft controlsthe opening and closing of intake and exhaust valves
according to certain valve timing through the tappet and push rod.
2.2
Lubricating system
Lubricating system
consists of oil strainer, oil pump, oil filter and all internal pipes. The
diesel engine adopts a combined lubrication method: pressure lubrication and
splash lubrication.For crankshaft main bearing, connecting rod bearing,
camshaft bearing and rockshaft and other parts, pressure lubrication is
adopted.Besides, some kinematic pairs, such as cylinder liner and piston,
piston pin and connecting rod, and piston pin seat, valve and valve guide, gear
and other parts rely on splash lubrication.
Oil is intake by oil
pump through filter screen, and compressed into oil filter.Filtered oil
lubricates the crankshaft main bearing, camshaft bearing and rocker arm bearing
through engine block main oil gallery.Lubricate the connecting rod bearing
through oil gallery in the crankshaft.
Oil filter adopts a
totally-closed spin-on type, during operation, if filter element is blocked,
the safety valve will automatically open and make oil flow into main oil
gallery directly, but at this moment, it has lost its function of filtration,
therefore, it is required to timely replace filter elements of oil filter
according to "Technical Maintenance" requirements. A pressure
regulating valve is set in the oil filter, which can adjust pressure in the
main oil gallery, maintaining it within the range of (200~500) kPa.
2.3
Fuel system
Fuel system consists of
fuel tank, coarse fuel filter, fuel delivery pump, diesel filter, fuel pump and
fuel injector.The diesel enters into fuel delivery pump through coarse fuel
filter, and it is delivered by the fuel delivery pump to the diesel filter;
after further filtration, it enters into fuel pump, and the high-pressure fuel
that comes out of fuel pump is injected into combustion room by the fuel
injector; the low-pressure fuel that comes out of fuel pump and the diesel that
leaks out of needle valve couple at port of fuel injector flow back to fuel
tank, as is shown in Figure 2-2.
1. fuel return pipe; 2.
high-pressure fuel pipe; 3. diesel filter; 4. fuel tank; 5. fuel filter; 6.
fuel injection pump
The fuel delivery pump
is of single-functional piston type, and installed on the outer side of fuel
injection pump, it is driven by the eccentric gear on the camshaft of fuel
injection pump, what's more, there is a manual fuel pump on the fuel delivery
pump, before start-up of diesel engine, loosen the bleeder screw, and unscrew
the manual fuel pump handle, tilt it up and down reciprocally to pump fuel and
exhaust the air, making the whole fuel pump filled up with fuel.After finishing
the air bleeding, the handle should be screw up, in order to avoid fuel
leakage.
Diesel filter is used for
separating mechanical impurities in the diesel, and reducing wearing of plunger
couple and nipple needle valve couple.Blockage or damage of filter element, it
is necessary to replace it.
The fuel injection pump
is a BQ pump, electronic governor.The fuel injection pump is driven by fuel
injection pump timing gear, through the fuel injection pump camshaft, idler
wheel and tappet, making the plunger move reciprocally in the plunger liner.
The control mechanism which changes the fuel volume is made up of adjusting
pull rod, shifting fork and adjusting arm pressed on the plunger, and the
position of pull rod is controlled by the governor, when the pull rod move
forward, the fuel supply raises, otherwise, declines.
Before delivery of
engine out of factory, the fuel injection pump has been adjusted and
lead-sealed by manufacturer; users shall not disassemble it at will.When it is
necessary to disassemble or repair, adjusting test should be conducted on test
bench for fuel pump.
The fuel injector is of
P Series, which is compressed up by a compression bolt and a flat clamp, the
height of nozzle sticking out of cylinder head bottom surface can be adjusted
with a gasket.The fuel injector should be maintained as specified in these
instructions, in which, the needle valve couple are ground in pair, when
disassembling, they shall not be exchanged, and should be kept clean.
2.4
Cooling system
The cooling system is
forced circulation water cooling, as is shown in Figure 2-3.
It includes radiator,
water pump, fan, and thermostat and so on.When the temperature of cooling water
in engine block is lower than 73°C, the thermostat does not open, and the
cooling water is circulating inside the engine (namely small circulation), making
the temperature of water in the engine rise rapidly so that the engine reaches
thermostability as soon as possible. When the temperature of cooling water
reaches 80°C, the thermostat gradually opens, at the same time, the small
circulation is closed. Cooling water enters into radiator through thermostat,
reenters water pump after cooled by fan, and then enters engine block,
fulfilling the big circulation.
This engine adopts
centrifugal water pump, and the water pump adopts self-lubricating inner integral
ball bearing, so no need to fill in lubricating grease. During use, when the
water seal is worn, and there is serious water leakage in the water hole below
the water pump body, it is necessary to replace the water seal.
2.5
Electric appliance
Electric system includes
storage battery, starter, alternator, relay governor, electric lock, preheating
start-up switch and ammeter, etc.
The alternator is of
JFWZ13 (14V/25A, in-built governor and reserved speed sensor binding post) AC
shunt excitation alternator.It is formed by rectifying three-phase alternator
and silicon diode, connect the negative electrode to the earth, never connect
in the opposite direction; otherwise, the alternator will be damaged.
The starter is a series
excitation DC motor(12V/3kW) of type QDJ1408L-P.The once continuous service
time of starter shall not be longer than 10s, and the interval between twice
start-ups is 2 min, if consecutive 3 times of start-ups all fail, it is
necessary to check and troubleshoot. For the overhaul and troubleshooting
methods of starter, please refer to "Operation and Maintenance
Instructions for Starter".
The storage battery is
of type 6Q-140, and voltage is 12V. Before use, the storage battery should be
initially charged by filling in battery solution according to the
specification.During use of the storage battery, please note that:
1. Frequently check the
height of battery solution at least once a week, when the height is lower than
(10~15) mm, it is necessary to add distilled water or other purified water, and
it is forbidden to use well water or river water.
2. Normally keep
unblocked the small air hole in the nut cover over the port of solution, and
the outer surface of battery should be kept clean and dry.
3. Normally keep the
quantity of electric charge of storage battery not less than 75%.When the
storage battery is discharged by up to 50%, and then it's time to charge it.
The discharging degree of storage battery can be check by aerometer or
discharging instrument.
4. If any used storage
battery will not be used again temporarily, before parking, it should be fully
charged, and be recharged once a month after that.In the parking period, do not
pour out the battery solution.
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