FIELD OF INVENTION
This invention relates to improved piston of diesel engine. This invention is
particularly directed to piston of four stroke diesel engine'for reducing friction
of piston skirt with no compromise on guidance.
It is known to have been provided four stroke diesel engine with piston. In the
four stroke diesel engine (as shown in fig. I), one cycle is selected from the
following four stages.
1. Suction stroke - Piston moves from Top dead centre to bottom dead
centre and air is sucked into the cylinder.
2. Compression stroke- Piston moves from bottom dead centre to centre
with intake valve closed and air is compressed.
3. Power stroke- Diesel is injected into the cylinder at high pressure leading
to burning of diesel and movement of the piston from top dead centre to
bottom dead centre producing power.
4. Exhaust stroke- Exhaust gases are thrown out of cylinder as piston
moves from bottom dead centre to top dead centre.
Fig. 1 indicates the following:-
Intake stroke (I), compression stroke (2)' power stroke (3), exhaust stroke (4),
Inlet valve (5)' exhaust valve (6), fuel injector (7) and spray of diesel through
nozzle (8).
The piston skirt profile comprises a barrel shape with a linear drop and ovality
in horizontal plane.
As can be seen from the vertical profile (in fig. 1 ') the linear drop is continuous
and smooth in nature.
OBJECTS OF THE INVENTION
The primary object of the present invention is to provide improved piston of
diesel engine which reduces friction of piston skirt and power loss.
Another object of the present invention is to provide improved piston of diesel
engine which reduces fuel consumption in engine and COz emissions.
Further object of the present invention is to provide improved piston of diesel
engine which is efficient and reliable.
Yet another object of the present invention is to provide improved piston of
diesel engine with improved SFC.
SUMMARY OF THE INVENTION
According to this invention, there is provided an improved piston of diesel
engine comprising of atleast one slot on anti thrust side of piston .skirt to
reduce sliding friction between piston and liner.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings and wherein:
Fig. 1 shows: diesel engine in four stroke.
Fig. 1' shows: skirt profile of piston according to prior art.
Fig. 2 shows: piston skirt profile with special slot(s) on anti thrust side (ATS).
Fig. 3 shows: piston skirt profile with special slot(s) on trQst side (TS) and anti
thrust side (ATS).
19 GEC 20%
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS:-
This invention discloses an improved piston of diesel engine. Said piston
comprising of a plurality of special slots on anti thrust side of pist~ns kirt to
reduce sliding friction between piston and liner. Further, the slots can be
provided in a unique asymmetrical combination on thrust and anti thrust side.
This provision leads to improvement in fuel consumption in engines and
reduction of carbon dioxide emissions.
Piston skirt comprising a barrel profile in cold condition so as to become almost
cylindrical in hot condition due to uneven expansion of piston material.
Since the guidance of the piston in liner is critical for proper functioning of
piston rings as well as to achieve performance parameters like blow by, low oil
consumption and reduction in slap sound.
Normally the piston skirt profile is symmetric in nature with linear drop in
vertical direction and oval in horizontal direction as shown in fig. 2.
Reference may be made to fig. 2, wherein atleast one special slot
(Depression)(S) is provided on anti thrust side (ATS) of the'piston skirt so as to
reduce sliding friction between the piston and liner.
In another embodiment as shown in fig. 3, a plurality of special depressions are
provided on both Thrust and ATS sides in unequal number. This is provided
considering the load applicability on TS and ATS sides.
However, in another embodiment of present invention, the special depressions
(S) can be provided on both thrust and anti thrust sides in equal number.
The special depression can be parabolic or any other curve in the master
I
profile. The depression could be atleast one in number. These depression can
be on both Thrust and Anti thrust side depending on peak cylinder pressure.
Alternatively, it can only be on anti thrust side.
These depressions result in reduced friction of skirt zone and also reduced fuel
consumption.
It is to be noted that the present invention is susceptible to modifications,
adaptations and changes by those skilled in the art. . Such variant
embodiments employing the concepts and features of this invention are
intended to be within the scope of the present invention, which is further set
1 forth under the following claims:
WE CLAIM:
1. An improved piston of diesel engine comprising of atleast one slot on anti
thrust side of piston skirt to reduce sliding friction between piston and
liner.
2. An improved piston of diesel engine as claimed in claim 1, wherein the
slot (s) can be provided in a unique asymmetrical combination on thrust
and anti thrust side of piston.
3. An improved piston of diesel engine as claimed in claim 1 or 2, wherein
the slot (S) can be provided in equal number on both thrust and anti
thrust side of piston.
4. An improved piston of diesel engine as claimed in any of the preceding
claims, wherein the slot (depression) can be any curve such as parabolic.
5. An improved piston of diesel engine as claimed in any of the preceding
claims, which results in reduced friction of skirt zone and also reduced
fuel consumption, thereby reducing emission of carbon dioxide.
6. An improved piston of diesel engine substantially as herein described
with reference to the accompanying drawings.