1.Wear
of piston ring groove
The piston ring moves in
the ring groove, so that the piston ring groove is subject to the maximum wear
in the height direction, so that it becomes a ladder or trapezoid. The main reason
of wear is the unit pressure of piston ring on the groove wall and the
influence of high temperature. The wear rate of ring groove depends on the
roughness of piston ring plane and the structure of piston to a great extent.
Solutions: When the wear
of the piston ring groove is widened and the side clearance of the piston ring
is greater than the specified allowable value, the piston ring groove can be
turned on the lathe according to the enlarged piston ring.
2.Wear
of piston pin seat hole
The wear of piston pin
seat hole is generally smaller than that of piston ring groove. The wear rate
depends on the roughness of piston pin hole and the fit between piston pin and
pin hole. Due to the action of gas pressure and inertia force, the wear of
piston pin seat hole is not round, and the biggest wear occurs in the direction
perpendicular to the piston crown.
Solutions: When the wear
of the piston pin seat hole exceeds the specified value, the pin hole shall be
reamed to the repair size with a reamer, and an enlarged piston pin shall be
equipped.
The selection and
matching of piston pin shall be based on the inner diameter of the worn pin
hole, and the enlarged piston pin (generally 0.025-0.05mm larger than the inner
diameter of the pin hole) which is similar to the inner diameter shall be
selected. If you still feel loose when selecting the largest piston pin, you
should re select the piston. The
selected piston pin is new, and its conicity and out of roundness shall not
exceed 0.005mm. For multi cylinder diesel engines, the quality difference of piston
pin of each cylinder shall not exceed 10g. The interference between piston pin
and pin seat hole shall be 0.025-0.04mm under normal temperature (15-25
degrees).
3.Wear
of piston skirt
When the piston is in
normal operation, its skirt is perpendicular to the piston pin seat hole, due
to the effect of side pressure, the cylinder wall is directly rubbed, and the
surface of the cylinder has regular wispy wear marks. When the piston is
working, its head seldom contacts the cylinder wall because of the piston ring,
because of the strong heat on the top, the metal is also thick and easy to
expand. Although the skirt is in contact with the cylinder wall, its unit
pressure is not large, and the lubrication condition is good, so the wear is
also small. Because of the side pressure produced when the piston and
connecting rod run at high speed, the piston will form radial wear.
Therefore, the
measurement of piston availability depends on the increased clearance between
the piston and the cylinder wall. The increase of clearance will aggravate the
wear of piston and cylinder wall. The rotating speed is unstable, the power
decreases, the oil consumption increases, and the exhaust gas emits blue smoke.
Solutions: When the wear
of the piston skirt, the out of roundness and taper of the piston skirt are
greater than the specified value, they should be replaced.
Generally, the piston
can be inspected by observation and judgement after being damaged. When the
exhaust pipe of diesel engine emits blue smoke and the power drops, most of the
faults occur in the ring groove or piston ring; when the engine is idling, the
air leakage in the crankcase can be heard. It is difficult to repair the
piston. When the piston is seriously worn, burnt or broken, it should be replaced
with a new piston of the same model.
If the piston of diesel generator set fails, it will hinder the normal operation of the unit.
Therefore, if you find the piston fault of the unit, you must repair it in
time.
Starlight Power is a manufacturer of power generating set in Jiangsu China, founded in 1974. We are not only provide technical problem solutions, but also supply high quality diesel generator set (20kw-3000kw), if you have purchase plan, do not hesitate to contact us by email sales@dieselgeneratortech.com, we will guide you to select the most suitable genset.
Comments
Post a Comment