DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10, rule 13]

TITLE:
“A LUBRICATION ARRANGEMENT FOR A CAM AND A CAM-FOLLOWER OF AN INTERNAL COMBUSTION ENGINE”

NAME AND ADDRESS OF THE APPLICANT:
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, INDIA.

Nationality: Indian

The following specification particularly describes the invention and the manner in which it is to be performed.
TECHNICAL FIELD

The present disclosure generally relates to an internal combustion engine. Particularly, but not exclusively, embodiments of the disclosure disclose a lubrication arrangement for a cam and a cam-follower of the internal combustion engine.

BACKGROUND OF THE DISCLOSURE
Internal combustion engines, such as those operating on a four-stroke principle, are provided with at least one intake valve and at least one exhaust valve. The intake and exhaust valves are disposed in intake and exhaust passages respectively. They are actuated to open and close the passages in order to control the flow of air and fuel into a combustion chamber of the engine and the flow of exhaust gases out of the combustion chamber. Various mechanisms exist to actuate the movement of the valves. One such mechanism includes a camshaft, a plurality of cams and cam follower, and a rocker mechanism. The valves are operated by a rocker mechanism which coverts rotary motion of the cam to linear motion of the valve. The rocker mechanism will comprise of a cam-follower for example roller-follower which follows the cam, and rocker arm carrying an adjuster screw which is pivoted to a rocker shaft. The adjuster screw will make contact with the valves for opening, and a spring provided in the valve will move the valves back to closed position. The camshaft is disposed for rotation in the cylinder head assembly of the engine, and is driven by a crankshaft through a timer belt. The plurality of cams is disposed on the camshaft for rotation therewith. The cam follower/roller follower will be connected to one end of the rocker arms. Rotation of the camshaft causes the cam to engage the cam follower such that the cam follower rotates and makes the oscillatory motion of rocker arm, thereby allows valve to an open position where the passage associated with the valve fluidly communicates with the combustion chamber. The spring biases the valve back to a closed position, thus preventing fluid communication between the passage and the combustion chamber.

During the operation, there is a lot of heat generated between the camshaft, cam and cam-follower due to frictional force because of contact of metal to metal surfaces. Such metal to metal contact of the cam and cam-follower cause wear and tear of the components and efficiency of the entire engine decreases. Also, ware of the cam and cam-followers requires frequent changing of the parts in the engine, thereby increases the maintenance cost of the engine. Hence, there is a need to overcome these limitations by avoiding wear and tear, and excess heat.
Conventionally, lubrication of different engine components are achieved by means of oil mist generated within engine housing. The oil mist coats engine components, and lubricates any surfaces of contact between them. This mist might not reach into upper regions of the housing below engine cover, i.e. where cam and followers are there. This can result in metal to metal contact between cam and followers leading to excessive wear, and need for frequent readjustment and replacement of parts.

In recent past, engine manefacturers have developed a system for lubricating some parts of the engine which are enclosed in the engine head cover. In such systems a lubrication oil will be supplied to the engine head cover through oil galleries, and then to different component’s such as cam shaft bearing surfaces, and rocker arm bearing surfaces through oil passages. However, even in such arrangements the lubrication oil is not supplied onto the cam and cam-follower contact surface. Hence, the problem associated with ware of the surfaces due to metal to metal contact is still remains unsolved.

In light of the foregoing discussion, it is necessary to develop a lubrication arrangement for a cam and a cam-follower of the internal combustion engine to overcome the one or more problems stated above.

SUMMARY OF THE DISCLOSURE

The shortcomings of the prior art are overcome and additional advantages are provided through the provision of system as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure there is provided a lubrication arrangement for an internal combustion engine. The arrangement comprising at least one cam shaft comprising a plurality of cams rotatably mounted in an engine head. A first rocker shaft and a second rocker shaft mounted parallel to the at least one cam shaft, wherein each of the first rocker shaft and second rocker shaft comprises a plurality of rocker arms pivotally mounted thereon and engaging the at least one cam shaft for actuating valves of the internal combustion engine. A first oil gallery fluidly connected to an engine head oil gallery, wherein the first oil gallery is configured to supply lubrication oil to the first rocker shaft and the second rocker shaft. Particularly, in the lubrication arrangement, at least one of the first rocker shaft and the second rocker shaft comprises a plurality of first radial holes for lubricating at least one of the cam and the cam-follower contact surfaces, wherein at least one of the plurality of radial holes are oriented towards the at least one of cam and cam-follower contact surface.

In an embodiment of the present disclosure, the engine head oil gallery is fluidly connected to second oil gallery of the internal combustion engine. The second oil gallery of the internal combustion engine is fluidly connected to oil sump. Further, the one oil pump is provided in between the oil sump and the second oil gallery.

In an embodiment of the present disclosure, the first and second rocker shafts comprises a plurality of second radial holes for lubricating cam bearing surfaces, and a plurality of third radial holes for lubricating rocker arm bearing surfaces.

In an embodiment of the present disclosure, the first and second rocker shafts are hollow shafts, and are concealed at both the ends. Further, the dimension of the plurality of first radial holes ranges from about 0.5mm to 2mm.

In an embodiment of the present disclosure, the engine head comprises a third oil gallery for supplying the oil collected in the engine head to the oil sump.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

OBJECTIVES OF THE DISCLOSURE

One object of the present disclosure is to provide a lubrication arrangement for a cam and a cam-follower of an internal combustion engine which effectively lubricates the contact surface between cam and cam-follower.

One object of the present disclosure is to provide disclosure is to provide a lubrication arrangement for a cam and a cam-follower of an internal combustion engine, which is simple in construction, and easy to assemble.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG. 1 illustrates a sectional side view of an internal combustion engine, in accordance to an embodiment of the present disclosure.

FIG. 2 illustrates another sectional side view of an internal combustion engine of FIG.1.

FIG. 3 illustrates a top view of an internal combustion engine of FIG.1.

FIG. 4 illustrates perspective view of a rocker shaft for the internal combustion engine, in accordance to some embodiment of the present disclosure.

FIG. 5 illustrates sectional view of the rocker shaft of FIG. 4.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

To overcome the drawbacks mentioned in the background, the present disclosure provides a lubrication arrangement for cam and cam follower of the internal combustion engine. Generally, Inlet and Exhaust valve opening in Internal Combustion (I.C) engines is brought about by a rocker arm pivoted on a rocker shaft. The first end of the rocker arm is provided with a cam-follower, and is set in oscillatory motion by a cam mounted on the cam-shaft and connected to it by a reciprocating push rod. The second end of rocker arm consists of an adjustable screw with a lock-nut to push the valve stem to bring about the opening and closing of valves. When the rotating cam reaches its peak position, the push rod pushes the first end of rocker arm about the rocker shaft which causes the adjustable screw in second end of rocker arm to come in contact with the spring-loaded valves. This causes opening of valves against spring force. When the cam rotates further and reaches the dwell position, the valves return to initial positions under the spring force. Hence, during the operation of the engine the cam-follower on each of the rocker arm makes rolling contact with the cam, thereby metal to metal contact will happen. Hence, the present disclosure provides a lubrication arrangement for cam and cam follower of the internal combustion engine which reduces ware due to metal to metal contact of the cam and the cam-follower.

The lubrication arrangement for cam and cam follower of the internal combustion engine comprises a first oil gallery fluidly connected to an engine head oil gallery for receiving the lubrication oil supplied to an engine head oil gallery from the main oil gallery of the engine. The first oil gallery comprise of two outlet ports fluidly connected to a first rocker shaft and a second rocker shaft. In an embodiment of the disclosure, the first and the second rocker shafts are hollow shafts and are configured as longitudinal oil flow paths. The first rocker shaft and the second rocker shaft are provided with a plurality of first radial holes for lubricating at least one of the cam and the cam-follower contact surfaces. The plurality of first radial holes are oriented towards the at least one of cam and cam-follower contact surface such that the lubrication oil flowing through the first and second rocker shafts will be impinged onto the contact surface of cam and cam-follower contact surface. Due to oil jet, mist environment will be created inside the head cover which will help to provide proper lubrication to cam lobe follower. This prevents metal-metal contact of the cam and cam-follower, thereby reduces the ware of components in the engine.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup system, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

Reference will now be made to figures which are exemplary embodiments of the present disclosure, as illustrated in the accompanying drawings. Where ever possible referral numerals will be used to refer to the same or like parts.

FIGS. 1-3 are exemplary embodiments of the present disclosure which illustrates sectional view and top view of the internal combustion engine (E). The internal combustion engine (E) includes a cylinder block having a bank of cylinders containing pistons connected with a crankshaft (not shown). A cylinder head also refereed as engine head (104) carries intake and exhaust valves (114) of the engine. The engine head (104) is configured to enclose the intake and exhaust valves (114) of the engine, along with cam drive mechanism. Further, a camshaft (103) is rotatably disposed in the cylinder head assembly (104) of the engine, and is driven by a crankshaft through suitable mechanism such as but not limiting to a timer belt. The cam shaft (103) is supported inside the engine head (104) through a plurality of camshaft bearings (not shown). In an embodiment of the disclosure, the cam shaft bearings are slider bearings such as but not limiting to journal bearing. The term journal bearing refereed herein refers to a bearing in which the shaft is separated from the bearing surface through a thin oil film, in other words due hydrodynamic lubrication. The cam shaft (103) is provided with a plurality of cams (101) alternatively referred as cam lobes for operating the inlet and exhaust valves (114) of the engine. The cams (101) rotates along with the cam shaft for operation of the valves (114) of the engine (E). In an embodiment of the present disclosure, the number cams (101) on the cam shaft (103) will be equivalent to the total number of inlet and exhaust valves (114) in the engine (E). Further, the cams (101) are oriented such that first set of the plurality of cams (101) are configured to operate the inlet valves (114), and the second set of the plurality of cams (101) configured to operate the exhaust valves (114).

As shown in FIG. 1 each of the inlet and exhaust valves (114) are operated by a rocker mechanism comprising a rocker arm (107) which carries adjusting screw which contacts a spring valve retainer of the valve, and cam-follower (102) at the other end. In an embodiment of the present disclosure, the cam-follower is a roller follower and makes rolling contact with the corresponding cam (101) on the cam shaft (103). The rocker arms (103) are held in an engine head (101) by a pair of rocker shafts (105 and 106). In an embodiment of the disclosure, the pair of rocker shafts is a first rocker shaft (105) and second rocker shaft (106) carrying rocker arms (107) of the inlet valves (114) and the exhaust valves (114) respectively. The first and the second rocker shafts (105 and 106) are mounted in the engine head (104) such that the axis of the first and the second rocker shafts (105 and 106) are parallel to the axis of the cam shaft (103). Each of the rocker arms (107) is pivoted on to the first and second rocker shafts (105 and 106) through a rocker shaft bearing (not shown). In an embodiment of the disclosure, the first and second rocker shafts (105 and 106) are configured as hollow shafts and are concealed at the ends. The hollow portion of the first and second rocker shafts (105 and 106) is configured as oil passage. As shown in FIG. 2 oil flow from main oil gallery of cylinder block to rocker shaft. Lubricant oil flows from main gallery also called as second oil gallery (111) of cylinder block to engine head oil gallery (109). Oil then flows through radial slot also called as first oil gallery (108) on camshaft bearing to the first and second rocker shafts (105 and 106). The lubrication arrangement (100) comprises an oil pump (not shown) in between the second oil gallery (111) and an oil sump (not shown). In an embodiment of the disclosure, the oil pump is a concentric pump, and is used for pressurising and supplying oil in the oil sump (not shown) to the engine oil galleries. Further, in some embodiments of the disclosure, an additional oil gallery along with oil filter is provided in between oil sump to second oil gallery to purify the oil stored in the sump.

Further, the engine head (104) is provisioned with an oil collection chamber for collecting the lubricating oil impinged on the engine components. A third oil gallery (not shown) is provisioned between oil collection chamber and the oil sump for supplying the lubrication oil back to the oil sump. In an embodiment of the disclosure, the lubrication oil flows through the third oil passage using gravitational force.

FIGS. 4 and 5 are exemplary embodiments of the present disclosure illustrating perspective view and sectional view of the first and second rocker shaft (105 and 106). The first and second rocker shafts (104 and 105) are configured as hollow shafts and are concealed at the ends. The hollow portion of the first and second rocker shafts (105 and 106) is configured as oil passage. The first and second rocker shafts (105 and 106) comprises a plurality of first radial holes (110) for lubricating at least one of the cam (101) and the cam-follower (102) contact surfaces (115). In an embodiment of the present disclosure, the number of first radial holes (110) in each of the first and second rocker shaft (105 and 106) is equal to number of cam and cam-follower contact surfaces (115). Further, each of the plurality of first radial holes (110) are oriented towards the at least one of cam (101) and cam-follower (102) contact surface (115) for impinging the lubrication oil on the corresponding cam (101) and cam-follower (102) contact surface (115) [shown in FIG. 1]. This results in formation of mist environment on the cam (101) and follower (102) which will help to provide proper lubrication to cam follower. This smoothens metal-metal contact of the cam and cam-follower, thereby reduces the ware of components in the engine. In an embodiment of the present disclosure, the diameter of the plurality of first radial holes (110) ranges from about 0.5mm to 2mm. In an exemplary embodiment, the plurality of first radial holes (110) are formed in 0.7mm diameter to lubricate camshaft and roller of rocker arm to avoid less oil pressure and improper lubrication of rocker arm roller (102) and cam (101).

Further, the first and second rocker shafts (105 and 106) are provisioned with a plurality of second radial holes (112) for lubrication of the camshaft bearing surfaces (not shown). In an embodiment of the present disclosure, the diameter of the plurality of second radial holes (112) ranges from about 3mm-5mm. In an embodiment of the present disclosure, the number of second radial holes (112) in each of the first and second rocker shaft (105 and 106) is equal to number of cam bearings. In addition, the first and second rocker shafts (104 and 105) are provisioned with third radial holes (113) for lubrication of the rocker arm bearing surfaces (not shown). In an embodiment of the present disclosure, the diameter of the plurality of third radial holes (113) ranges from about 1.5mm-4mm. In an embodiment of the present disclosure, the number of third radial holes (113) in each of the first and second rocker shaft (105 and 106) are equal to number of rocker arms (107) carried by each of the he first and second rocker shaft (105 and 106). The second and third radial holes (112 and 113) of the first and second rocker shafts (105 and 106) will inject the lubrication oil onto the camshaft bearing surface and the rocker arm bearing respectively.

The dimensions of the first, second and the third radial slots (110,112, and 113) given the present disclosure are exemplary embodiments of the disclosure. One skilled in the arts may vary the dimensions first, second and the third radial slots depending on various factors such as size of the engine, pressure of the oil, and the like. Hence, one should not consider the exemplary dimensions as limitation to the present disclosure.

Additionally, advantages of present disclosure are illustrated herein.
The present disclosure provides a lubrication arrangement for a cam and a cam-follower of an internal combustion engine which effectively lubricates the contact surface between cam and cam-follower thereby reduces the ware due rubbing of metallic surfaces. This provides long life cam follower by providing additional lubrication in contact area. This lubrication is to take care of effects of increased contact stresses due to high valve spring preload to sustain increased combustion chamber for turbocharged gasoline engine upgraded from base naturally aspirated engine for performance improvement.

The present disclosure provides a lubrication arrangement for a cam and a cam-follower of an internal combustion engine, which is in simple in construction, and easy to assemble. Also, the arrangement utilises existing rocker shaft as oil flow passage for lubricating the contact surface between cam and cam-follower thereby reduces the additional cost and parts in the internal combustion engine.

The present disclosure provides a lubrication arrangement for a cam and a cam-follower of an internal combustion engine, which improves oil film formation ratio on its rolling surface and make it possible to form an oil film thick to prevent metal to metal contact at rolling contact surface to prevent peeling and wear on the rolling surface of the roller irrespective of the roughness of mating cam surface. Thus life of the cam follower is increased.

Equivalents:

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Referral Numerals:

Reference Number Description
100 Lubrication arrangement
101 Cam
102 Cam-follower
103 Cam shaft
104 Engine head
105 First rocker shaft
106 Second rocker shaft
107 Rocker arm
108 First oil gallery
109 Engine head oil gallery
110 First radial hole
111 Second oil gallery
112 Second radial hole
113 Third radial hole
114 Valves
115 Contact surface
E Internal Combustion Engine, or Engine

,CLAIMS:We claim:

1. A lubrication arrangement (100) for an internal combustion engine (E), the arrangement (100) comprising:
at least one cam shaft (103) comprising a plurality of cams (101) rotatably mounted in an engine head (104);
a first rocker shaft (105) and a second rocker shaft (106) mounted parallel to the at least one cam shaft (103), wherein each of the first rocker shaft (105) and second rocker shaft (106) comprises a plurality of rocker arms (107) pivotally mounted thereon and engaging the at least one cam shaft (103) for actuating valves (114) of the internal combustion engine;
a first oil gallery (108) fluidly connected to an engine head oil gallery (109), wherein the first oil gallery (108) is configured to supply lubrication oil to the first rocker shaft (105) and the second rocker shaft (106);
characterized in that,
at least one of the first rocker shaft (105) and the second rocker shaft (106) comprises a plurality of first radial holes (110) oriented towards the at least one of cam (101) and cam-follower (102) for lubricating at least one of the cam (101) and the cam-follower (102) contact surfaces (115).

2. The arrangement (100) as claimed in claim 1, wherein the engine head oil gallery (109) is fluidly connected to second oil gallery (111) of the internal combustion engine (E).

3. The arrangement (100) as claimed in claim 2, wherein the second oil gallery (111) of the internal combustion engine is fluidly connected to oil sump.

4. The arrangement (100) as claimed in claim 3, wherein at least one oil pump is provided in between the oil sump and the second oil gallery (111).

5. The arrangement (100) as claimed in claim 1, wherein the first and second rocker shafts (105 and 106) comprises a plurality of second radial holes (112) for lubricating camshaft bearing surfaces.

6. The arrangement (100) as claimed in claim 1, wherein the first and second rocker shafts (105 and 106) comprises a plurality of third radial holes (113) for lubricating rocker arm bearing surfaces.

7. The arrangement (100) as claimed in claim 1, wherein the first and second rocker shafts (105 and 106) are hollow shafts, concealed at both ends thereof.

8. The arrangement (100) as claimed in claim 1, wherein dimension of the plurality of first radial holes (110) ranges from about 0.5mm to 2mm.

9. The arrangement (100) as claimed in claim 1, wherein the engine head (104) comprises a third oil gallery (114) for supplying the oil collected in the engine head (104) to the oil sump.

10. A vehicle comprising a lubrication arrangement (100) for cam and cam-follower of an internal combustion engine (E) as claimed in claim 1.

Dated this 10th Day of November, 2014 GOPINATH A.S.
IN/PA 1852
OF K&S PARTNERS
AGENT FOR THE APPLICANT