The present disclosure relates to oil supply systems for hydraulic lash adjustments.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
Hydraulic lash: The term 'hydraulic lash' mentioned in the description refers to an increase or a decrease in the clearance maintained between the components of a valve train, especially the rocker arm and the valve stem of the valve train, due to wear and tear, or due to thermal expansion and contraction of the components of the valve train. The hydraulic lash causes an increase or decrease in the effective length of the valve train, which impacts the performance of the engine.
Hydraulic lash adjuster: The term 'hydraulic lash adjuster' mentioned in the description refers to a device or an arrangement that would enable the lash to be adjusted and therefore neutralize it, thereby improving the performance of the engine.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
An engine cylinder head is provided with a valve train having a plurality of rocker arms attached thereto. Each rocker arm is provided with a hydraulic lash adjuster, commonly known as a lifter. The rocker arm includes an oil passage which connects the rocker arm to the lash adjuster. The lash adjuster is configured to regularize the effective length of the valve train during a positive lash or a negative lash either by expansion or contracting a plunger of the lash adjuster. In

particular, for the expansion of the plunger, it is necessary to supply pressurized oil into the hydraulic lash adjuster.
Conventionally, pressurized oil is provided from a sump via an oil gallery formed in the cylinder head. The oil gallery connects the oil gallery to a camshaft opening, of the crankcase structure, through which the oil trickles in. The camshaft opening is configured to receive a camshaft therein. The camshaft comprises a pair of end bearings and a plurality of cam lobes separated by bearing journals provided therebetween. Each cam lobe is configured to rotate at half the revolution of the engine, to abut a rocker arm to open the valve. An oil hole is configured on the camshaft journal. When the camshaft journal rotates, the oil hole of the camshaft journal rotates there along to fluidly communicate with the oil passage of the rocker arm, and facilitate oil flow into the lash adjuster.
However, the flow of the oil into the camshaft opening depends on the engine speed. Hence, the oil flow into the oil passage occurs intermittently which may sometimes cause the hydraulic lash adjuster to be deprived of the oil supply, thereby preventing the hydraulic lash adjuster from neutralizing the positive lash.
There is therefore felt a need for an oil supply system that alleviates the aforementioned drawback.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide an oil supply system for hydraulic lash adjustment of a valve train.
Another object of the present disclosure is to provide an oil supply system for hydraulic lash adjustment of a valve train, which ensures continuous supply of oil for adjusting the hydraulic lash.

Yet another object of the present disclosure is to provide an oil supply system for hydraulic lash adjustment of a valve train, which has a simple configuration that can be installed in any type of valve train.
Still another object of the present disclosure is to provide an oil supply system for hydraulic lash adjustment of a valve train which is a cost-effective solution.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages an oil supply system for hydraulic lash adjustment of an engine valve train.
The oil supply system comprises a main oil gallery configured to be in fluid communication with an oil sump. The oil supply system further comprises a camshaft in fluid communication with the oil gallery. The camshaft comprises a plurality of cam lobes, end bearings, and at least one intermediate camshaft bearing journal. A groove is defined on the intermediate camshaft bearing journal. The groove is configured to receive the pressurized oil from the oil gallery and facilitate continuous flow thereof to enable hydraulic lash adjustment.
In an embodiment, the valve train comprises a plurality of rocker arms. Each rocker arm comprises an oil passage configured therein to facilitate fluid communication of the rocker arm with a hydraulic lash adjuster.
In an embodiment, the oil gallery includes a pump configured to pump the pressurized oil from the sump.
In another embodiment, a camshaft opening is configured in an engine crankcase. The camshaft opening is configured to receive the camshaft therein. The camshaft opening is configured to be in fluid communication with the oil gallery to enable the grooved camshaft to receive pressurized oil from the oil gallery.

In yet another embodiment, the groove forms an oil pocket to continuously supply pressurized oil irrespective of the valve timing.
In one embodiment, clearance between the camshaft opening and the groove ranges between 100 microns and 160 microns.
In another embodiment, ratio of diametrical dimension of the bearing journal to diametrical dimension of the groove ranges between 6 and 7.
In yet another embodiment, the depth of the groove ranges between 2mm and 7mm.
In still another embodiment, diameter of the oil gallery ranges between 8mm and 12mm.
In one embodiment, the pressurized oil is engine oil.
The present disclosure further envisages a multi-cylinder internal combustion engine comprising a cylinder head, a valve train provided in the cylinder head, a plurality of hydraulic lash adjusters, an oil sump containing pressurized oil, and an oil supply system for supplying pressurized oil to the hydraulic lash adjusters. The valve train has a plurality of rocker arms. Each hydraulic lash adjuster is in fluid communication with a rocker arm.
The oil supply system, of the multi-cylinder internal combustion engine, comprises a main oil gallery configured to be in fluid communication with an oil sump. The oil supply system further comprises a camshaft in fluid communication with the oil gallery. The camshaft comprises a plurality of cam lobes, end bearings, and at least one intermediate camshaft bearing journal. A groove is defined on the intermediate camshaft bearing journal. The groove is configured to receive the pressurized oil from the oil gallery and facilitate continuous flow thereof to enable hydraulic lash adjustment.
In an embodiment, the rocker arm has an oil passage configured therein. The oil passage is configured to facilitate fluid communication between the camshaft and the hydraulic lash adjuster.

In another embodiment, the multi-cylinder internal combustion engine includes a camshaft opening configured in an engine crankcase. The camshaft opening is configured to receive the camshaft therein. The camshaft opening is further configured to be in fluid communication with the oil gallery to enable the grooved camshaft to receive pressurized oil.
The present disclosure also envisages a vehicle having the oil supply system, as described in the present disclosure, for supplying pressurized oil to enable hydraulic lash adjustment of an engine valve train.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
An oil supply system, of the present disclosure, for hydraulic lash adjustment of an engine valve train will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a front view of the oil supply system of the present disclosure;
Figure 2 illustrates a cross-sectional view of the system of Figure 1;
Figure 3 illustrates an isometric view of an oil path, from the oil sump to an HLA, of the system of Figure 1;
Figure 4 illustrates a cross-sectional view of the oil supply system of the present disclosure;
Figure 5 illustrates an isometric view of a camshaft of the system of the present disclosure;
Figure 6 illustrates a side view of a camshaft of the system of the present disclosure; and
Figure 7 illustrates a side view of a rocker arm with an HLA provided therein.
LIST OF REFERENCE NUMERALS

5 crankshaft
10 engine cylinder head
20 rocker arm
30 oil sump
35 pump
40 hydraulic lash adjuster (HLA)
100 oil supply system
105 main oil gallery
110 camshaft
111 camshaft opening
112 cam lobe
114 end bearing j ournal
116 intermediate camshaft bearing journal
118 groove
120 crankshaft

125 external oil passage to HLA
127 suction strainer
129 oil filter
130 relief valve assembly
132 incoming oil gallery from pump
134 oil cooler
136 lube oil cooler to filter
138 lube oil pipe from filter to cooler
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a," "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," "including," and "having," are open ended transitional phrases and therefore specify the presence of stated features, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, operations, elements, components, and/or groups thereof.
When an element is referred to as being "mounted on," "engaged to," "connected to," or "coupled to" another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as "inner," "outer," "beneath," "below," "lower," "above," "upper," and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
An oil supply system (100), of the present disclosure, for hydraulic lash adjustment of an engine valve train will now be described with reference to Figure 1 through Figure 7.
An engine cylinder head (10) is provided with a valve train having a plurality of rocker arms (20) attached thereto. Each rocker arm (20) is provided with a hydraulic lash adjuster, commonly known as a lifter. The rocker arm (20) includes an oil passage which connects the rocker arm (20) to the lash adjuster. The lash

adjuster is configured to regularize the effective length of the valve train during a positive lash or a negative lash either by expansion or contracting a plunger of the lash adjuster. In particular, for the expansion of the plunger, it is necessary to supply pressurized oil into the hydraulic lash adjuster.
Conventionally, pressurized oil is provided from a sump (30) via a main oil gallery (105) formed in the cylinder head (10). The oil gallery (105) connects the oil gallery (105) to a camshaft opening (111), of the crankcase structure, through which the oil trickles in. The camshaft opening (111) is configured to receive a camshaft (110) therein. The camshaft (110) comprises a pair of end bearing journals (114) and a plurality of cam lobes (112) separated by intermediate bearing journals (116) provided therebetween. Each cam lobe (112) is configured to rotate at half revolution of the engine to abut a rocker arm (20) to open the valve. An oil hole is configured on the camshaft journal. When the camshaft journal rotates, the oil hole of the camshaft journal rotates there along to fluidly communicate with the oil passage of the rocker arm, and facilitate oil flow into the lash adjuster.
However, the flow of the oil into the camshaft opening (111) depends on the engine speed. More specifically, the hole in the camshaft journal enables oil supply to the lash adjuster for particular angle of camshaft rotation, typically 180deg. Hence, the oil flow into the oil passage occurs intermittently which may sometimes cause the hydraulic lash adjuster to be deprived of the oil supply, thereby preventing the hydraulic lash adjuster from neutralizing the positive lash.
There is therefore felt a need for an oil supply system (100) that alleviates the aforementioned drawback.
Figure 1 illustrates a front view of the oil supply system of the present disclosure;
Figure 2 illustrates a cross-sectional view of the system of Figure 1;
Figure 3 illustrates an isometric view of an oil path, from the oil sump to an HLA, of the system of Figure 1;

Figure 4 illustrates a cross-sectional top view of the oil supply system of the present disclosure;
Figure 5 illustrates an isometric view of a camshaft of the system of the present disclosure;
Figure 6 illustrates a side view of a camshaft of the system of the present disclosure; and
Figure 7 illustrates a side view of a rocker arm with an HLA provided therein.
The oil supply system (100) comprises a main oil gallery (105) configured in the cylinder head (10). The oil gallery (105) is configured to be in fluid communication with the sump (30) containing pressurized oil. The oil supply system (100) further comprises a camshaft (110) provided on the cylinder head (10). The camshaft (110) is configured to be in fluid communication with the oil gallery (105). The camshaft (110) comprises end bearing journals (114), and at least one intermediate camshaft bearing journal (116) having a groove (118) configured thereon. The groove (118) is configured to receive the pressurized oil from the oil gallery (105), and facilitate continuous flow of pressurized oil to enable hydraulic lash adjustment of the valve train.
More specifically, the groove (118) is configured to act as an oil pocket which receives the pressurized oil and can supply the oil to the rocker arm (20), and therefore to the hydraulic lash adjuster continuously irrespective of the valve timing.
In an embodiment, the groove (118) is machined on the bearing journal (116).
In an embodiment, the oil gallery (105) includes a pump configured to pump the pressurized oil from the sump (30). In another embodiment, the pressurized oil is engine oil. In yet another embodiment, the oil supplied to the lash adjuster has a predetermined pressure range varying between 1.2 bar and 2 bar.
In one embodiment, the system (100) includes a camshaft opening (111) configured in an engine crankcase. The camshaft opening (111) is configured to

receive the camshaft (110) therein. The camshaft opening (111) is configured to be in fluid communication with the oil gallery (105) to enable the grooved camshaft (110) to receive pressurized oil from the oil gallery (105).
In an embodiment, clearance between the camshaft opening (111) and the groove (118) ranges between 100 microns and 160 microns.
In another embodiment, the ratio of diametrical dimension of the bearing journal (116) to diametrical dimension of the groove (118) ranges between 6 and 7.
In yet another embodiment, the depth of the groove (118) ranges between 2mm and 7mm.
In still another embodiment, the diameter of the oil gallery (105) ranges between 8mm and 12mm.
The system (100) of the present disclosure, ensures that the continuous supply of oil to the hydraulic adjuster is provided by simply providing the groove on the
The present disclosure further envisages a multi-cylinder internal combustion engine comprising a cylinder head (10) and a valve train provided in the cylinder head (10). The valve train has a plurality of rocker arms (20). The engine further comprises a plurality of hydraulic lash adjusters. Each hydraulic lash adjuster is configured to be in fluid communication with a rocker arm (20). Additionally, the engine comprises a sump (30) containing pressurized oil, and an oil supply system (100) for supplying pressurized oil to the hydraulic lash adjuster.
The oil supply system (100) comprises a main oil gallery (105) configured in the cylinder head (10). The oil gallery (105) is configured to receive pressurized oil from the sump (30). The oil supply system (100) of the engine further comprises at least one camshaft (110) in fluid communication with the oil gallery (105). The camshaft (110) has at least a pair of cam lobes (112) and an intermediate camshaft bearing journal (116) having a groove (118) configured thereon. The groove (118) is configured to receive pressurized oil from the oil gallery (105), and facilitate

continuous flow of pressurized oil to enable hydraulic lash adjustment of the valve train.
In an embodiment, the rocker arm (20) has an oil passage configured therein. The oil passage is configured to facilitate fluid communication between the camshaft (110) and the hydraulic lash adjuster.
In one embodiment, the engine includes a camshaft opening (111) configured in an engine crankcase. The camshaft opening (111) is configured to receive the camshaft (110) therein. The camshaft opening (111) is further configured to be in fluid communication with the oil gallery (105) to enable the grooved camshaft (110) to receive pressurized oil.
The present disclosure further envisages a vehicle having an oil supply system (100), as described above, for supplying pressurized oil to enable hydraulic lash adjustment of an engine valve train.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of an oil supply system for hydraulic lash adjustment of a valve train, which:
• ensures continuous supply of oil for adjusting the hydraulic lash;
• has a simple configuration that can be installed in any type of valve train; and

• is a cost-effective solution.
The foregoing disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Any discussion of materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

CLAIM:

1. An oil supply system (100) for hydraulic lash adjustment of an engine
valve train, said system (100) comprising:
• a main oil gallery (105) configured to be in fluid communication with an oil sump (30);
• a camshaft (110), in fluid communication with said oil gallery (105), comprising a plurality of cam lobes (112), end bearing journals (114) and at least one intermediate camshaft bearing journal (116); and
• a groove (118), defined on said journal (116), configured to receive the pressurized oil from said oil gallery (105) and facilitate continuous flow thereof to enable hydraulic lash adjustment.

2. The oil supply system as claimed in claim 1, wherein said valve train comprises a plurality of rocker arms (20), each rocker arm (20) comprising an oil passage configured therein to facilitate fluid communication of the rocker arm (20) with a hydraulic lash adjuster.
3. The oil supply system (100) as claimed in claim 1, wherein said oil gallery (105) includes a pump configured to pump the pressurized oil from the sump (30).
4. The oil supply system (100) as claimed in claim 1, wherein a camshaft opening (111) is configured in an engine crankcase, said camshaft opening (111) being configured to receive said camshaft (110) therein, wherein said camshaft opening (111) is configured to be in fluid communication with said oil gallery (105) to enable said grooved camshaft (110) to receive pressurized oil from said oil gallery (105).

5. The oil supply system (100) as claimed in claim 1, wherein said groove (118) forms an oil pocket to continuously supply pressurized oil irrespective of the valve timing.
6. The oil supply system (100) as claimed in claim 1, wherein clearance between said camshaft opening (111) and said groove (118) ranges between 100 microns and 160 microns.
7. The oil supply system (100) as claimed in claim 1, wherein the ratio of diametrical dimension of said bearing journal (116) to diametrical dimension of said groove (118) ranges between 6 to 7.
8. The oil supply system (100) as claimed in claim 1, wherein the diameter of said groove (118) ranges between 2mm and 7mm.
9. The oil supply system (100) as claimed in claim 1, wherein the depth of said oil gallery (105) ranges between 8mm and 12mm.
10. The oil supply system (100) as claimed in claim 1, wherein the pressurized oil is engine oil.
11. A multi-cylinder internal combustion engine comprising:

• a cylinder head (10);
• a valve train provided in the cylinder head (10);
• a plurality of rocker arms (20) provided in said valve train;
• a plurality of hydraulic lash adjusters in fluid communication with the rocker arms (20);
• an oil sump (30); and
• an oil supply system (100) comprising:

o a main oil gallery (105) configured to be in fluid communication
with an oil sump (30); o a camshaft (110), in fluid communication with said oil gallery
(105), comprising a plurality of cam lobes (112), end bearing
journals (114) and at least one intermediate camshaft bearing
journal (116); and o a groove (118), defined on said journal (116), configured to receive
the pressurized oil from said oil gallery (105) and facilitate
continuous flow thereof to enable hydraulic lash adjustment of the
valve train.
12. The multi-cylinder internal combustion engine as claimed in claim 11, wherein said rocker arm (20) has an oil passage configured therein, the oil passage being configured to facilitate fluid communication between said camshaft (110) and a hydraulic lash adjuster.
13. The multi-cylinder internal combustion engine as claimed in claim 11, which includes a camshaft opening (111) configured in an engine crankcase, said camshaft opening (111) configured to receive said camshaft (110) therein, said camshaft opening (111) further configured to be in fluid communication with said oil gallery (105) to enable the grooved camshaft (110) to receive pressurized oil.
14. A vehicle having an oil supply system (100), as claimed in any one of the preceding claims, for supplying pressurized oil for hydraulic lash adjustment of an engine valve train.