DESC:Field of the invention
The present invention relates to a cylinder liner of combustion engines.

Background of the invention
Engine liner, also known as cylinder sleeve or liner is a very critical component especially in diesel engines. Many parameters of engine performance are related to the performance and/or physical condition of a liner. A major problem observed in the liners is cavitation, which may lead to severe damage to the liners including sudden blocking/seizure of the engine. Cavitation is a critical phenomenon wherein the outer surface of the liner gets corroded, mainly due to its contact with water or cooling liquid running around it through galleries (cavities) in the engine block. This decay may be severe and result in through holes exposing inside of the liner (which is combustion chamber) to the outer water-gallery, thus allowing water/coolant getting into the liner, that may lead the engine to suddenly stop functioning without any alarm. The problem is generally discovered during major engine repair that includes disassembling the head and removing the pistons.
Cavitation is usually not detected till the damage has caused a detrimental failure during its duty-cycle in the field. In cavitation, the engine liners are punctured due to bursting of bubbles formed during linear vibrations. The known reasons of cavitation include continuous erosion, mixing of water in oil, lack of lubrication, and improper cooling. It is noted that mixing of water in the oil ultimately results in improper lubrication and improper cooling. The engine stalls due to lack of cooling and lubrication. The problem of engine cavitation is typically observed in diesel engines for example, tractor engines. The only known solution to address the engine cavitation is the replacement of the destroyed liners with new identical liners.
The damage caused by cavitation erosion of diesel engine cylinder liner is a major problem for today’s engine manufacturers. Cross corrosion is a combination of mechanical and chemical action that causes corrosion. The corrosion forms an oxide layer on the liner wall. However, when the bubble collapses the oxide layer of corrosion might be removed. The combined effect of corrosion and erosion increases the damage rate over that from these processes acting separately.
Further, vibrations in the cylinder liner are induced by piston slap. Another cause of vibration is the flexing of cylinder wall due to high cylinder pressures experienced in the diesel engine ignition. The cavitation erosion is caused by excess in harmonic vibrations of the engine and in some cases by loose fitting of liners that result in last formation and implosion of small vapour bubbles within the coolant which attach the cylinder liner wall. Cavitation corrosion damage can completely penetrate the liner wall and result in coolant leakage into the combustion chamber creating the hazardous situation.
Hence, there is a need of a liner that can address at least one of the problems related to the cavitation of liners as discussed above.

SUMMARY OF THE INVENTION
Accordingly, in the first aspect, the present invention provides a liner of a combustion engine comprising a tubular body having a longitudinal axis and an undulated profile formed on one of the ends of the tubular body. According to the present invention, said undulated profile is defined by having a plurality of projections and a plurality of cuts at the end of said liner.
According to an embodiment of the present invention, the tubular body has a working area and a non-working area and the plurality of projections are provided at the end of the non-working area of the tubular body for reducing vibrations in the liner.
According to a preferable embodiment of the present invention, the projections are provided in the bottom end of the liner by providing the plurality of cuts in the tubular body of conventional length of the liner.
According to the preferable embodiment of the invention, a number of projections and cuts on the tubular body are same.
According to the present invention, a profile of the projections and depressions is a known geometrical shape, including U-shaped, “V” shape, wave shape.
According to the preferable embodiment of the present invention, a total arc length of projections is equal to half of the circumference of the liner.
In the second aspect, the present invention provides a combustion engine comprising at least one liner of the first aspect of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS:
The features, aspects and other advantages of the present invention can be better understood when the following description is read with reference to the accompanying drawings, wherein:
FIG.1 is a perspective of a liner in accordance with a preferred embodiment of the present invention;
FIG. 2 is a bottom view of the liner of the FIG. 1 showing a plurality of equidistant cuts defined in a bottom end of the liner; and
FIG. 3A and 3B is an enlarged view of a cut/depression and a projection of the liner of the FIG. 1 according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION:
The present invention in general provides a liner for a combustion engine of reciprocating piston. The liner comprises a tubular body having a longitudinal axis and defining a working area and a non-working area wherein a plurality of projections are provided at the bottom end of the non working area of the liner for reducing vibrations in the liner. According to the present invention, each projection provided on the non-working area of the liner acts as as a cantilever beam structure, reduces deformation in the liner and absorb strain energy which results in lesser vibrations of liner.
According to the present invention, the projections are provided in the bottom end of the liner by providing the cuts/depression in the cylinders without increasing the conventional length of the liner. Alternatively, the projections can be provided beyond the conventional length of the liner.
The embodiments of the invention shown and discussed herein are merely illustrative of modes of application of the present invention. References to details in this discussion are not intended to limit the scope of the claims to the said details, or to the figures used to illustrate the invention.
Now referring to FIGS. 1-3, the liner 100 of the present invention includes a plurality of equidistant through projections 106 defined at the bottom end 104 of the liner to address the problem of vibration and cavitation thereby to address the problem associated with sudden engine failure due to cavitation. Each projection of the liner acts as a cantilever beam, thereby reduce the vibrations. Resulting in reducing the problem of cavitation associated with the vibrations.
Referring to Figs. 1 and 2, a cylindrical liner 100 in accordance with a preferred embodiment of the present invention is shown. The liner 100 extends from a top end 102 to a bottom end 104. The liner 100 includes a plurality of projections 106 and cuts 107 that are defined at the bottom end 104 of the liner. The projections 106 are defined along the circumference of the bottom end of the liner 100. The projections 106 are preferably through cuts having a “U” shape.
In this preferred embodiment, the projections 106 are positioned on the bottom end 104 in such a way that the projections 106 are equidistant along the circumference of the bottom end 104 of the liner 100. The projections 106 are preferably defined using known manufacturing process in the art such as casting and machining.
Referring to FIG. 3A shows an enlarged view of the depression or cut 107 in accordance with the present invention and referring to FIG. 3B shows an enlarged view of the projection 106 in accordance with the present invention are shown. According to the present invention, dimensions of the projections and depressions/cuts depends on the vibration study in the particular combustion machine. According to the preferable embodiment of the present invention, the number of projections and depressions are same and can have similar dimensions. Alternatively, the dimensions of the projections and the depressions/cuts can be different. The liner shown in the Figures 1 and 2 has eight projections and eight cuts/depressions. However, the liner may have two or more projections depending upon the type of the combustion machine
A total arc length of projections can be equal to or more than half of the circumference of the liner. The total length of the projection is calculated as below
Total Length= N X L
Wherein,
N= Number of the projections; and
L= Arc length of a projection.
According to an embodiment of the present invention, a preferable profile of the projections and depressions is U-shaped. Alternatively, the profile can be of any known geometrical shape in accordance with the requirement such as “V” shape, wave shape etc.
It is to be understood that the invention is not limited in its application to the details of construction of the liner set forth in the description or as illustrated in the drawings. The projections acting as a cantilever beam can be easily understood by a person skilled in the arts. Further, a non working area and working area of the liner can be easily understood by the person skilled in the art. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways, including coating the liners with chrome, nickel, ceramic and the like. A person skilled in the art can be easily understood that any suitable material including but not limited to cast iron, aluminium, iron alloyed with chromium, vanadium and molybdenum etc. with/without plating can be used for manufacturing the liner of the present invention and the invention of the present invention cannot be limited to any material of constructions. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this invention is based may readily be utilized as a basis for the designing of other structures, methods and apparatus for carrying out the several purposes of the present invention.
The following example illustrates a liner having specific dimension manufactured according to the present invention as claimed and described, but is not limiting the invention the invention to the said dimensions thereof:
Example 1:
To carry out the experiment of vibration data collection, a diesel engine set up having four pistons was built in the laboratory and equipped with the necessary sensors to study vibrations and accelerometer. In the experiments, the liners were meshed with liner brick elements of the engine set up such that the liners were radially supported at the crankcase guiding location and vertically supported at the collar, bottom surface for dynamic analysis to study the dynamic behavior of the liners including the projections in accordance with the present invention. Tests were simulated based on the following observations:
1) Large acceleration takes place in the sweeping of speed from low idle to high idle within 2 seconds of time;
2) Also at 75 % load condition highest dominant frequencies and highest respective amplitude has been observed compared to other loading conditions
3) Engine cooling water contamination (Max. Chloride content, hardness) is able to decide which is severe enough to simulate field coolant qualities which lead to damage of liner by cavitation.
Accordingly, test cycle was derived and tests were conducted for 500hrs using the engine setup as discussed above. The cylinder liners of the present invention and the standard liner were tested on the setup. The cylinder liners of the present invention which were tested, each was having a length 173 mm along the axis-X. Each of the projections were defined in an inverted ‘U’ shape such that the height (H) of the respective projection was approximately 12mm and the end-to-end width of the cut was approximately 16mm. The radius (R) of the curvature of the projections 106 was approximately 4mm. The bottom end 104 of the liner 100 had 8 equidistant through projections 106.
In the first test, maximum displacements decided from three Acceleration data on the condition monitoring of the diesel cylinder liners based on the cylinder block surface vibration measured and used to prepare test load cycle for third and fourth liners to simulate the loading pattern as experienced in field operation. The deviations were measured for third and fourth liners as it was observed that maximum vibrations takes place at the said liners in the engine. Following Parameters monitored during Cavitation Testing: -
1) Engine Speed, Load - Continuous
2) Water temperature - Continuous
3) Engine oil pressure - Continuous
4) Exhaust Temp. - Continuous
5) Water condition - Daily
Liner cavitation (by dissembling of engine) - Every 250 hrs.
Table 1 shows a comparison of the acceleration data at standard deviations measured at Liner 3, Liner 4 and crankcase block for different engine and at different loads:

Table 1
Further, after 500 hrs of test, it was observed that clear cavitation marks on the standard liner and no cavitation on the liner of the present invention.
The conclusion of the test was that advantageous presence of the projections resulted in less vibration on the major thrust side and minor thrust side, preferably in the cavitation locations, relative to the known standard liners in the prior art.
,CLAIMS:WE CLAIM:
1. A liner of a combustion engine, comprising:
a tubular body having a longitudinal axis; and
an undulated profile formed at one of the ends of the tubular body, said undulated profile defined by having a plurality of projections and a plurality of cuts provided at the end of said liner.

2. The lines as claimed in claim 1, wherein the tubular body has a working area and a non-working area wherein the plurality of projections are provided at a bottom end of the non working area of the liner for reducing vibrations in the liner.

3. The liner as claimed in claim 1, wherein the projections are provided at the bottom end of the liner by providing the plurality of cuts in the tubular body of a conventional length of the liner.

4. The liner as claimed in claim 1, wherein the projections are provided at the bottom end of the liner extending beyond a conventional length of the liner.
5. The liner as claimed in claim 1, wherein number of projections and cuts are same.

6. The liner as claimed in claim 1, wherein a profile of the projections and depressions is a known geometrical shape, including U-shaped, “V” shape, wave shape.

7. The liner as claimed in claim 1, wherein dimensions of the projection and cut are similar.

8. The liner as claimed in one of the preceding claims 1 - 7, wherein a total arc length of projections is equal to or more than a half of the circumference of the liner.

9. A combusition engine comprising at least one line as claimed in one of the preceding claims 1-8 for reducing vibrations.
Dated this 29th day of November, 2014
FOR MAHINDRA & MAHINDRA LIMITED
By their Agent

(GIRISH VIJAYANAND SHETH) (IN/PA 1022)
KRISHNA & SAURASTRI ASSOCIATES