FIELD OF INVENTION
This invention relates to an improved piston liner kit used in the locomotives.
PRIOR ART
The piston assembly known in the art comprises of a piston functioning inside a chromium-plated liner. The liner is held in the engine block by a sleeve with two sealing rings between liner and sleeve with higher interference. The piston is of composite type with Aluminum body and steel cap clamped together by a single bolt. The piston is provided with five rings, out of which three rings provided in the body and two are in the steel cap.
However, the above said piston liner kit is associated with some draw backs listed herein below:
Seizure / failure of the pistons due to higher interference between liner and the sleeve and engine block.
- Higher interference causes collapse of the liner due to constriction
and resulting in major damages/ failures.
- Chrome peel off in the liner due to defective chrome plating or
during working conditions.
- Failure of liner and pistons assembly due to chrome peel off.
- Abrasion i.e. wear of piston groove, ring and liner etc due to the
*peel off/ *wear off of the chromium plating in the liner or Svear off
of the Ferrox fillings of the top ring and higher secondary
movement of piston 85 piston rings due to excessive clearance
between the piston and cylinder liner.
OBJECT8 OF THE INVENTION
The primary object of the present invention is to propose an improved piston liner kit used in the locomotives, which overcomes all the drawbacks associated with the prior art.
Another object of the present invention is to propose an improved piston liner kit used in the locomotives so as to improve performance of engine and increase life expectancy of components namely piston, ring and liner etc.
Further object of the present invention is to propose an improved piston liner kit used in the locomotives, which is efficient and also simple in construction.
SUMMARY OF THE INVENTION
According to this invention there is provided an improved piston liner kit used in the locomotives comprising of a liner held by a sleeve in the engine block with almost zero interference. The liner is non plated and high hardened one, housing a composite piston having a Aluminum piston body clamped with steel cap by a single bolt., The liner is provided with three sealing rings out of which two " O" sealing rings are accommodated in the bottom portion of liner lower OD . Another sealing ring is a flat one provided above the two "O" rings on the liner lower OD. These three sealing rings hold the liner with sleeves against zero interference. This also avoids the water leakage between liner and sleeve.
The piston of this invention is provided with three grooves accommodated with a ring pack in the crown zone.
STATEMENT OF INVENTION
According to this invention there is provided an improved piston liner kit used in the locomotives comprising of a liner held by a sleeve wherein the liner housing a composite piston having a piston body with a cap, the cap is provided with at least three grooves accommodated with a ring pack in which the liner comprises of three grooves on liner Lower OD, out of which top groove is provided with a flat sealing ring and remaining grooves with regular "O" rings.
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: Sectional view of piston body and its cap.
Fig. 2 shows: Liner of the present invention
Fig. 3 shows: Sleeve of the present invention
Fig. 4 shows: Fire ring of the present invention
Fig. 5 shows: Sealing ring used in the present invention
Fig. 6 shows: Top ring of the ring pack used in the present invention
Fig. 7 shows: Second ring of the ring pack
Fig. 8 shows: Third/last ring of the ring pack with coil spring.
DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
According to this invention, there is provided an improved piston liner kit used in the locomotives comprising of a composite piston with a profile as shown in Fig. 1 having an Aluminium body (1) with a cap (2) wherein the cap is provided with three grooves (3) so as to accommodate piston ring pack therein. The body is secured to the cap by means of a single stretch bolt (4), washer (6) and pin (7). Further, a fire ring (Fig.4) having a slightly smaller inner diameter than the cylinder bore and is inserted into the top part of the cylinder liner. The piston is also reduced diameter at the top, to maintain adequate clearance with fire ring. The bottom edge of the fire ring scrapes down the carbon deposits on the piston top flange. By this effect, carbon polishing on the liner surface can also be avoided and as a result, wear on the piston ring running surface is also reduced. Which results in reduction of Lube oil consumption and wear of liner and piston ring radial. The bottom edge of the fire ring scrapes down the carbon deposits. This helps in avoiding liner bore polishing to remove carbon deposit there from and also helps in reduction of wear of piston ring running surface.
As an additional effect of the fire ring, performances relating to the cylinder liner and the piston rings can be kept stable for long term since gas pressure on top of the compression rings can be kept as primary condition even after long-term operation. This is because it controls thickness of carbon on the piston top land, i.e. clearance between cylinder liner and piston top land remains constant.
The kit of the present invention comprising of a sleeve (Fig. 3) housing a liner (Fig.2) containing the said piston with less interference between the
liner and sleeve to avoid constriction which may lead to collapse. The liner is provided with three groves on lower OD, out of which two accommodate O-sealing ring in the 2nd and 3rd grooves. The third groove is located in the upper zone of liner lower outer diameter, which is projected out from the sleeve. One additional flat sealing ring as shown in fig. 5 is provided to secure the liner with sleeve and also to prevent the leakage of water past the liner.
The Crown portion of the piston is provided with a different profile and dimensional value of its groove as compared to the known art. The cap with three grooves serve the same purpose as that of prior art with the help of a ring pack comprising of a Top ring (fig. 6), middle ring (fig. 7) and oil ring (fig. 8).
The top ring is chrome ceramic coated for better wear resistance, scuff resistance and longer life.
The middle ring is chromium-plated ring and the oil ring accommodates a coil spring.
The combination of three rings helps in achieving excellent wear resistance and economy.
The selection of material for the liner depends upon two factors namely; correct bore surface character, and strength and fatigue resistance.
Centrifugal castings of high alloy cast iron can meet both of said requirements. Therefore, it is adopted for the present invention. However, it is to be noted that, liner surface is plain without any coating or even hardening process.
As per the calculated values, the piston liner clearance is reduced to 250microns compared to prior art where it is maintained at 400microns. This helps in reducing piston secondary movement. To accommodate this, liner bore dia is reduced by 150 microns. Reduction in the piston liner clearance leads to a significant reduction in piston secondary movement resulting in atleast 30% reduction of friction work. However, expected wear reduction is more than 30% as the wear pattern is not linear with the friction work.
The present invention offers reasonably acceptable and lower LOG values as compared to contemporary designs of the engine of same size and application.
The piston liner kit of the present invention can be used with the existing engine block with ease.
Effects of the present invention are as follows;
• Less lube oil consumption due to less wear of piston rings and
liner and also due to reduced secondary movement.
• Stable lube oil consumption performance for long term operation.
• Less maintenance efforts due to less contamination of exhaust
system (exhaust valves, exhaust pipes, TC) and less lube oil
consumption.
• Longer maintenance intervals.
• Longer life time of components.
• Lesser lube to fuel ratio.
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 forth under the following claims:-

WE CLAIM:
1. An improved piston liner kit used in the locomotives comprising of
a liner held by a sleeve wherein the liner housing a composite
piston having a piston body with a cap, the cap is provided with
atleast three grooves accommodated with a ring pack in which the
liner comprises of three grooves on liner Lower OD, out of which
top groove is provided with a flat sealing ring and remaining
grooves with regular "O" rings.
2. An improved piston liner kit used in the locomotives as claimed in
claim 1 wherein the kit comprises of a fire ring inserted into the
upper portion of the liner.
3. An improved piston liner kit used in the locomotives as claimed in
claim 1 or 2 wherein the ring pack comprising of three rings.
4. An improved piston liner kit used in the locomotives as claimed in
claim 3 wherein the three rings having a top ring, which is chrome
ceramic coated, middle ring, which is chromium plated tapered
ring and oil ring accommodating a coil spring.
5. An improved piston liner kit used in the locomotives as claimed in
any of the preceeding claims wherein the liner is not provided with
any coating.
6. An improved piston liner kit used in the locomotives substantially
as herein described with reference to the accompanying drawings.