FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
A Novel Camshaft And Rocker Shaft Mounting Arrangement For An Internal Combustion Engine
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. Rajendra M. Petkar, Mr. Amar S.Bakare
both Indian Nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner
in which it is to be performed

FIELD OF INVENTION
This invention relates to an internal combustion engine and more particularly this relates to mounting arrangement of camshaft and rocker shaft on a separate base carrier.
BACKGROUND OF THE INVENTION
Internal combustion engines are provided with cam shaft for actuating inlet and exhaust valves through rocker arms as per required valve timing and rocker shaft for supporting said rocker arms.
Conventionally double overhead camshafts are provided directly on the cylinder head by mounting lower half portion of the camshaft bearing on to said cylinder head and the other half bearing portion is covered with a cam cap or a integral cam cap cover.
The drawbacks associated with said mounting arrangement is that in case of six or more fastening units per cylinder the complexity of cylinder head increases and the said cylinder head becomes large and heavy in order to provide access to all fasteners.
US 4612885 relates to camshaft bearing arrangement for an overhead cam engine. In its more particular aspect, this prior art relates to an arrangement for rotatably supporting first and second camshafts associated with the first and second series of plural valves for the combustion chamber of an internal combustion engine.


The drawbacks associated with the said prior art are
a. It does not have provision to support rocker shafts; hence it is very
difficult to maintain the relation with valve train.
b. It requires unit to be machined along with the cylinder head in order to
maintain interrelationship with the valve train.
OBJECTS OF THIS INVENTION
The main object of this invention is to provide a novel camshaft and rocker shaft mounting arrangement for an internal combustion engine which will result in providing compact cylinder head ensuring accessibility to cylinder head fasteners.
Yet another object of this invention is to provide a novel camshaft and rocker shaft mounting arrangement for an internal combustion engine with light weight materials.
Yet another object of this invention is to provide a novel camshaft and rocker shaft mounting arrangement for an internal combustion engine which is simple in construction and cost effective.
BRIEF DESCRIPTION OF INVENTION
Cam shaft and rocker shaft mounting arrangement in accordance with this invention basically comprises of base carrier, cam caps, cylinder head and fastening arrangements. Wherein said base carrier is having a provision for supporting lower portion of the camshaft bearings along its length on either sides, and is also provided with supporting bores along the length on either side. Said base carrier is also provided with reliefs to clear injectors and their supporting arrangements. Said cam caps are fastened to the said base carrier to


support upper bearings and locate cam shaft in bore. The base carrier is detachably attached on the cylinder head by threaded fastenings. Rocker shafts are mounted on the base carrier on its supporting bores. To this rocker shafts, rocker arms are attached which further operate the inlet and exhaust valves according to the valve timing. For lubrication, different passages have been provided in the base carrier.
The main benefit in machining comes from the fact that it can be machined independent of the head, this is possible as because the rocker bores and cam bores are housed in the same component.
Thus this arrangement provides an ease of machining and assembly of the camshaft and rocker shaft with the cylinder head.
Disassembly of the said unit provides access to the bolts connecting cylinder head to the cylinder block. This feature helps in achieving a compact cylinder head.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows the sectional front view of the mounting arrangement for the cam
shaft and rocker shaft inside the valve train assembly
Fig. 2 shows the isometric view of the base carrier for mounting cam shaft and
rocker shaft.
Fig. 3 shows the front view of the base carrier for mounting cam shaft and
rocker shaft.
Fig. 4 shows the top view of the base carrier for mounting of the cam shaft and
rocker shaft


DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawing, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.
In the embodiment illustrated in figure 1, valve actuating mechanism for only one engine cylinder has been shown, however it is understood that the same mechanism is used for actuating valves for rest of the cylinders, in case of a multicylinder engine.
Referring to the figure 1, Cam shaft (2) and rocker shaft (3) mounting arrangement in accordance with this invention basically comprises of base carrier (1), cam caps (4), cylinder head (12) and fastening arrangements (13). Wherein said base carrier (1) is having a provision (7) for supporting lower portion of the camshaft bearings along its length on either sides, and is also provided with supporting bores (6) along the length on either side. Said base carrier (1) is also provided with reliefs (5) & (9) in order to clear injectors and their supporting arrangements (not shown) respectively. Said cam caps (4) are fastened to the said base carrier (1) by fastenings (13) through holes (8), to support upper bearings and locate cam shaft (2) in bore. The base carrier (1) is detachably attached on the cylinder head (12) by threaded fastenings (13). Rocker shafts are mounted on the base carrier on its supporting bores (6). To this rocker shafts, rocker arms (11) are attached which further operate the inlet and exhaust valves according to the valve timing. For lubrication, different passages (10) have been provided in the base carrier (1).


The main benefit in machining comes from the fact that base carrier (1) can be machined independent of the head cylinder (12), this is possible as the rocker bores (6) and cam bores (7) are housed in the same component. Thus this arrangement provides an ease of machining and assembly of the camshaft and rocker shaft with the cylinder head (12). Disassembly of the said unit provides access to the fasteners (13) connecting cylinder head (12) to the cylinder block. This feature helps in achieving a compact cylinder head (12).
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such alterations and modifications be included in, so far as they come within the scope of the invention as claimed or the equivalents thereof.


We Claim
1. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine comprises of base carrier, cam caps, cylinder head and plurality of fastening means, wherein said base carrier is having a provision along its length for supporting lower portion of the camshaft bearings, said base carrier is provided with plurality of supporting bores for rocker shafts, plurality of relief s to clear injectors and their supporting arrangements, said cam caps are fastened to said base carrier to support upper portion of bearings and locate cam shaft in bore, said base carrier is detachably attached on the cylinder head.
2. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine as claimed in claim 1 wherein said base carrier is having a provision along its length for supporting lower portion of the camshaft bearings on either side.
3. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine as claimed in claim 1 wherein said base carrier is provided with plurality of supporting bores for rocker shafts along the length on either sides.
4. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine as claimed in claims 1 to 3 wherein said rocker shaft supports plurality of rocker arms to operate the inlet and exhaust valves according to the valve timing.
5. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine as claimed in claims 1 to 4 wherein said base carrier is


further provided with one or more passages for lubrication of cam shaft bearing.
6. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine as claimed in claims 1 to 5 wherein threaded fastenings are used.
7. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine as claimed in claims 1 to 6 wherein said cylinder head has got six or more bolt per cylinder.
8. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine as claimed in claims 1 to 7 wherein said base carrier is made of a light weight material.
9. Cam shaft and rocker shaft mounting arrangement for an internal combustion engine substantially as herein described with reference to accompanying drawings.




ABSTRACT
A Novel Camshaft And Rocker Shaft Mounting Arrangement For An Internal Combustion Engine
This invention relates to the base carrier for an internal combustion engine. The base carrier is basically a light weight component, which can be fastened on the cylinder head after the cylinder head bolts have been fastened to the requisite torque levels. Rocker shafts can also be mounted inside the base carrier. Various arrangements have also been provided inside the base carrier for guiding the fuel injector, injector mounting arrangement, mounting of the bearings supporting the camshaft, lubrication of these bearings and fixing the cam caps on the camshaft. The base carrier fits inside the cylinder head, and thus provides a light and compact arrangement for the mounting of rocker shaft and camshaft along with an additional advantage of ease in machining.