FIELD OF INVENTION

This invention relates to an improved cylinder head gasket to improve the
sealing in exhaust side oil return gallery.

PRIOR ART

Currently available cylinder head gasket used in the gasoline engine with
compression ratio (9.2:1) is provided with silicon beading to seal the oil return
gallery as shown in Fig. 1. This silicon beading is provided on the graphite
composite base material. However, when the compression ratio exceeds 10.0,
in durability testing of cylinder head gasket, this silicon beading is not able to
seal this joint properly causing oil leakage. Hence, it is required to develop ah
improved cylinder head gasket so as to overcome the problem of oil leakage
from exhaust side. Now, reference may be made to the following known arts:-

FR 2385905A1:- The cylinder head gasket according to the invention
comprising a material located between the sides of the metal edges of the
combustion chamber having an inner annular area of which the bonding
material surrounding seal is interrupted.

US 5890719A:- This discloses a gasket for interposition between a cylinder
head and block of an internal combustion engine. The gasket includes a metal
retainer member having generally planar first and second surfaces with at leas$
one cylinder bore opening formed therethrough and at least one fluid port
opening formed therethrough. One or more elastomeric members are attached
to the retainer about a corresponding one of the fluid port openings.

US 20030155720A1:- A gasket includes an intermediate layer having resilient
sealing beads flanked by stopper beads. The three-layer gasket, particularly
designed for heavy duty racing engines, provides a relatively robust cross-
section in web-areas between cylinder bore apertures. A thin bottom layer
includes wrap-around flanged portions. A thin top layer overlies the
intermediate layer, as well as the overlapping portions of the bottom layer.

US 201 10101625A1:- The present invention relates to a multi-layer steel
insert for a cylinder head gasket for an internal combustion engine. The
cylinder head gasket may be made from metal or a composite material, and i~
disposed between a cylinder head and a cylinder block. The MLS insert may be
located around at least one fluid passage aperture. The MLS insert has a first
outside layer and a second outside layer each comprising an upper surface and
a lower surface, an outer perimeter, an inner closed perimeter defining a fluid
aperture, and a bead.

OBJECTS OF THE INVENTION

The primary object of the present invention is to provide an improved cylinder
head gasket to improve the sealing in exhaust side oil return gallery which
overcomes disadvantages associated with the prior art.

Another object of the present invention is to provide an improved cylinder head
gasket to improve the sealing in exhaust side oil return gallery which is reliable
and efficient.

Further object of the present invention is to provide an improved cylinder head
gasket to improve the sealing in exhaust side oil return gallery which is cost
effective.
STATEMENT OF INVENTION

According to this invention, there is provided an improved cylinder head gasket
to improve the sealing in exhaust side oil return gallery disposed between
cylinder head and cylinder block wherein said cylinder head gasket comprising
of a plurality of oil return galleries provided with resilient material coated
metallic grommets on the exhaust side for better sealing and reliable joint
avoiding oil leakage.

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 accompanyin~
drawings and wherein:

Fig. 1 shows: conventional cylinder head gasket.

Fig. 1' shows: oil return gallery partially free from copper.

Fig. 2 shows: exploded view of cylinder head gasket assembly.

Fig. 3 shows: improved cylinder head gasket of the present invention.

Fig. 4 shows: sectional view of oil return galleries of the head gasket.

DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE

ACCOMPANYING DRAWINGS: -

Presently known cylinder head gasket used for the gasoline engine is indicated
in fig. 1. The gasoline engine having compression ratio of 9.2:1 is provided with
silicon beading (1) so as to seal the oil return gallery on exhaust side (2). This
silicon beading is provided on the graphite composite base material. However,
when the compression ratio exceeds 10.0, in durability testing of cylinder head
gasket, this silicon beading is not able to seal the joint efficiently leading to oil
leakage.
Therefore, the present invention is directed to an improved cylinder head
gasket of internal combustion gasoline engine to improve the sealing in exhaust
side oil return gallery so as to address the aforesaid disadvantages associated
with the existing cylinder head gasket.

Now, reference may be made to fig. 2-4. The improved cylinder head gasket (3)
of internal combustion gasoline engine to improve the sealing in exhaust side
oil return gallery comprising of a plurality of oil return galleries provided with
resilient material coated metallic grommets (6) on the exhaust side. Said
cylinder head gasket (3) is positioned between cylinder head (4) and cylinder
block (5).

The base material of said cylinder head gasket is preferably made of graphite so
as to make it cost effective.

The resilient material is such as rubber and the metallic grommet is made of
for ex. copper without restricting scope of the invention to the same.

Referring to fig. 4, which shows Graphite base material (7) provided with a
rubber coating (8) on copper grommet (9).

These copper grommets provide more reliable joints and avoid crushing of
graphite composite material during working of engine. However, the oil return
gallery area is partially free from copper (as shown in fig. 1') SO as to
accommodate expansion in high temperature. Partially free copper area is
located on a surface facing cylinder head. Cylinder head is made of aluminum
alloy and cylinder block is made of casting iron.

Rubber coating is provided on copper grommets (9) to enhance the micro level
surface sealing in oil return galleries.
Reference may be made to fig. 2 showing exploded view of cylinder head gasket
assembly in which cylinder head gasket provides a sealing joint between
cylinder head & cylinder block. Cylinder head is assembled on cylinder block
with the help of cylinder head bolts. Hot oil from Camshaft area returns back
from oil return galleries "A", "B" & "C" to pass through cylinder head gasket
galleries "D", "E" & "F", which finally goes to oil sump through cylinder block
gallery "G", "H" & "J".

Thus, this invention is directed to a rubber coated copper grommet on oil
return gallery passage of a composite graphite gasket in a gasoline engine with
compression ratio more than 10.0.

Generally for Gasoline engines having compression ratio more than 10.0, Multi
layer Steel (MLS) cylinder head gaskets are used. However, it is expensive du~
to steel. Hence, in this invention Composite graphite cylinder head gasket with
combination of metallic (Copper) grommets is used to meet the sealing
requirements and also to make it cost effective.

When compression ratio is high in gasoline engines, sealing requirements of
cylinder head gasket increases due to higher firing pressure & temperatures~
To improve sealing in oil return galleries of cylinder block & cylinder head joint
face, cylinder head gasket should be able to provide reliable joint to avoid oil
leakage. This sealing requirement is more severe in exhaust side of cylinder
head as compared to intake side due to higher exhausted gas temperatures.

In this invention to improve the sealing in exhaust side oil return galler~
cylinder head gasket is modified by adding rubber coated copper grommets.
These rubber coated copper grommets provide better sealing and reliable joint
to avoid oil leakage.
It is to be noted that, the grommet material (e.g. copper) to be used as oil
gallery side should be softer than the grommet material (e.g. steel) used at
cylinder bore side. The softer material grommet at oil gallery side ensures
lesser pressure at oil gallery side as compared to cylinder bore side which is
desired to avoid any bore to bore leakage. Further, resilient material coated
metallic grommets is also provided to form micro level surface sealing.

Advantageous Features

1. Better sealing ability in exhaust side oil return gallery due to presence 6f
copper grommets
2. Copper grommets avoid crushing of base material (Graphite composite)
during operation of engine.
3. Rubber coating present on copper grommets provides micro sealing on
* surface of cylinder head & cylinder block.
4. Cost effective as compared to metallic gasket
5. Light weight as compared to metallic gasket of same thickness.

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 cylinder head gasket to improve the sealing in exhaust side
oil return gallery disposed between cylinder head and cylinder block
wherein said cylinder head gasket comprising of a plurality of oil return
galleries provided with resilient material coated metallic grommets on the
exhaust side for better sealing and reliable joint avoiding oil leakage.
2. An improved cylinder head gasket as claimed in claim 1, wherein the
cylinder head gasket, base material of which is preferably made of
Graphite.
3. An improved cylinder head gasket as claimed in claim 1 or 2, wherein the
resilient material is such as rubber.
4. An improved cylinder head gasket as claimed in any of the preceding
claims, wherein the metallic grommet is preferably made of copper.
5. An improved cylinder head gasket as claimed in any of the precedin~g
claims, wherein the oil return gallery area is partially free from copper so
as to accommodate expansion in high temperature such as herein
described.
6. An improved cylinder head gasket as claimed in claim 5, wherein said
partially free area is located on a surface facing cylinder head.
7. An improved cylinder head gasket as claimed in any of the preceding
claims, wherein said gasoline engine is having compression ratio more
than 10.0.
8. An improved cylinder head gasket to improve the sealing in exhaust side
oil return gallery substantially as herein described with reference to th~
accompanying drawings.