Damage Characteristics of Diesel Generator Camshaft
by Starlight Generator dieselgeneratortech1. Diesel
generator set cam face wear
When the camshaft is at rated
speed, the linear speed is up to 1.3 m/s. During the oil supply process of
driving the plunger upward, the friction and pressure of the cam surface are
quite large due to the compression pressure of the fuel and the spring
pressure. When the point of death is turned, the back side of the cam is
subjected to the impact of the elastic force. Therefore, there are different degrees
of wear on both sides of the cam, especially on the side of the cam lift, in
addition to the wear, and a little fatigue pit. When the cam wears up to 0.3
mm, it will obviously affect the accuracy of the oil supply time and the fuel
injection continuous angle, resulting in poor engine fire, power and economy.
When there is a pit in the surface of the genset cam, the surface roughness
will decrease, and if it continues to be used, it will accelerate the wear.
2. Diesel
generator set camshaft neck wear
The journal and the inner ring of
the ball bearing are tightly fitted and generally do not wear. After the
individual shafts wear out, the radial clearance is increased, which affects
the speed regulation performance of the engine.
3. Diesel
generator set cam keyway wear
Generally, it is not common. In some cases,
the installation of the transmission bushing is loose, so that the impact
occurs during operation and wear. After wear, the oil supply time will lag
behind.
4. Diesel
generator set camshaft broken
The broken part is mostly on the
tapered cylinder of the shaft head. This is because a small number of camshafts
have inherent defects during manufacture, fatigue wear during operation, and
finally lead to breakage or jamming or breaking of the plunger, causing the
camshaft transmission torque to rise significantly, exceeding the permissible
stress of the camshaft, due to the conical head taper. The section of the part
is small and it is easy to break here.
Common damage causes and
maintenance methods for camshafts of diesel generator sets
Damage to the camshaft of the
diesel generator set will directly affect the timing of the valve timing and
fuel supply timing of the diesel generator set, and damage the normal operation
of the generator set in severe cases. Therefore, it is very important to
eliminate the cause of the damage of the cam surface of the diesel generator
set and reduce the failure rate. The reasons for the damage of the diesel
generator set are analyzed, and the maintenance method of the camshaft is
discussed to improve the maintenance quality of the camshaft of the fuel
injection pump of the diesel generator set.
Common
causes of damage to camshafts of diesel generator sets
1. When the oil pump is
assembled, if the axis of the push rod is deflected during the assembly
process, the roller and the camshaft cam are not in line contact, but a point
contact occurs, resulting in uneven force, causing the roller to roll poorly,
resulting in the roller and the cam. Work surface wear is intensified.
2. The lower body of the fuel
injection pump and the cam are pressure-lubricated, and the oil is supplied to
the lower body of the pump through the hollow bolt, the small copper pipe for
supplying oil, and the joint body, and the cam and the roller are lubricated,
which is often caused by the blockage of the hollow bolt, the small copper pipe
and the joint body. The oil is not smooth, the heat generated by the cam and
the roller can not be lost in time, initially causing the cam and the roller to
be injured. The roller copper sleeve is worn out of excess, and the roller
rolling on the cam causes the impact on the roller, which aggravates the wear
of the copper sleeve and the positioning pin, sometimes Causes the copper
sleeve to lock on the pin. Sliding friction occurs between the roller and the
cam, as the roller forms an irregular ellipse and the top of the cam is
severely damaged.
3. The clearance between the
valve body and the push rod is too large. Due to improper fitting of the push
rod, the clearance between the valve body and the push rod is too large, and
the clearance between the push rod and the roller pin is too large, which can
cause the guide pin to be poorly guided, and the roller axis and the cam axis
are deviated, resulting in deviation The gas distribution roller is indexed at
a small angle to injure the camshaft valve cam.
Diesel
generator set camshaft inspection method
1. Check the axial clearance of
the camshaft, press the camshaft end, tilt the cam axial side, adjust the hands
to "0", and then move the cam shaft to the other side. The indication
value of the hands is the axial direction. The gap (0. 05~0. 15 mm is normal).
If the axial clearance exceeds the specified value, it can be adjusted by
replacing the adjustment spacers of different thicknesses. If the axial
clearance is too large, replace the thinner gasket; if the axial clearance is
too small, replace the thicker gasket. If the camshaft is left at 0. 05 mm, the
right gasket (thickness is also 0. 05 mm) is taken out and placed on the left.
2. Check the camshaft curvature.
If the degree of curvature exceeds 0.05 mm, the method of cold pressing should
be used for repeated straightening. It is not advisable to use a hammer (hand
hammer) to hard-hit. There are only two cases of camshaft bending: one is the
bending of the central part of the camshaft; the other is the bending of the
end of the camshaft (the end connected to the automatic oil feeder), which is
equipped with a gear-driven type of oil supply. When the automatic advancer is
used, the front end of the camshaft is most often bent. This kind of bending
makes the tapered roller bearing set at the front end of the camshaft the most
powerful, which makes the bearing race "out of the circle", the
bearing cover loose and outward, the camshaft turbulence increases, the cam,
the tappet ball The wear of the timing gears that mesh with each other in the
gearbox is accelerated. In severe cases, the bearing roller support frame may
be broken, the lubricating oil in the pump may leak from the loose bearing
cover edge, the timing gear may be cracked, etc., therefore, the cam The
bending of the shaft must be straightened in time.
3. Check the journal at the oil
seal of the camshaft. If the depth of the groove is more than 0. 10 mm, repair
repair is required. Check the cooperation of the camshaft keyway and the
semicircle key. Check the camshaft taper and threads. If it is rough or
damaged, use a stone to grind or replace the camshaft. Check the cam on the
camshaft and replace the camshaft if it is damaged, deformed or severely worn.
The amount of cam wear should not exceed 0.5 mm. Check the radial runout of the
camshaft. If it exceeds 0.5 mm, it should be cold-pressed. Check the camshaft
axial clearance. If it exceeds 0.15 mm, adjust or replace the camshaft.
4. Grinding the cam profile and
roller, the roller and cam profile ensure uniform contact during assembly; the
pusher body and the pump lower body should be carefully cleaned before
inspection and check whether the roller surface is pocked or scratched, and its
rotation and roller axle whether the up and down movement is flexible and
whether the gap is too large.
Sponsor Ads
Created on Nov 19th 2018 20:58. Viewed 291 times.