Note: Descriptions are shown in the official language in which they were submitted.
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1 AN INTERFERENCE FIT CYLINDER LINER
This invention relates to an interference fit cylinder liner
for an internal combustion engine and more particularly to an
interference fit cylinder liner for high compression engines.
Background of the Invention
The use of cylinder liners in engine blocks has been known
for many years. The principle purpose of such liners is to
reduce the cost of remachining the cylinder bores of an engine
after a long period of operation. In addition, such liners aid
in sealing the engine head to the engine block and therefore help
in preventing combustion gases from leaking into other parts of
the engine. Two common examples of conventional cylinder liners
are taught in U.S. patent 2,617,401, issued in 1952 to Rippingille
and in U.S. patent 2,721,542, issued in 1955 to Sheppard. With
advances in technology, the internal pressures of combustion
engines has increased; and today, it is not uncommon to find
engines opera-ting with combustion pressures within the range of
10,000 to 20,000 kilo Pascals.
These higher combustion pressures have proven detrimental to
an engine's sealing gaskets and have also reduced the ability of
the conventional liners to seal off leaking combustion gases.
Such gas leakage is hazardous to an engine in that it affects the
operating performance, causes starting difficulty, reduces
engine compression and adversely affects the heat transferability
of the engine coolant.
Now an interrerence fit cylinder liner has been invented
which is capable of preventing combustion gases from leaking to
other parts of an engine. This new cylinder liner is particularly
useful in high compression engines, such as high pressure diese~
engines, where it is even more desirable to stop combustion gas
leakage.
The general object of this inven-tion is to provide an
interference fit cylinder liner for an internal combustion
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1 engine. A more specific object of this invention is to provide
an interference fit cylinder liner for high compression engines.
Another object of this invention is to provide an interfer-
ence fit cylinder liner which can prevent combustion gases from
leaking into other parts of an engine.
Still another object of this invention is to provide an
interference fit cylinder liner which will reduce the force
needed to clamp the engine head onto the engine block, especially
where high peak firing pressures are present.
Other objects and advantages of this invention will become
apparent to one skilled in the art based upon the ensuing descrip-
tion.
Summary of the Invention
Briefly, this invention relates to an interference fit
cylinder liner for use in an internal combustion engine. This
interference fit cylinder liner is constructed of a long hollow
cylindrical one-piece member which is open at both ends. The
inner surface of the liner is smooth and has a uniform diameter
so that a piston can reciprocate therein. At one end of the one-
piece cylindrical member is a thin wall portion which contains acircumferential convex cross-sectional contact surface which is
capable of being deflected inward. This thin wall portion extends
above the top surface of the cylinder block and con-tacts the
inner surface of the engine head. As the engine head, which
contains a circular pocket, is mounted to the engine block, the
thin wall portion of the cylinder liner is deflected inward.
This inward deflection, caused by the thin wall portion contacting
the inner circumferential surface of the circular pocket, produces
an interference fit between the engine head and the thin wall
portion of the cylinder liner. The interference fit is sufficient
to prevent the leakage of gases out of the combustion chamber and
into other parts of the engine, even when high peak firing pres-
sures are present.
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1 Brief Desc tion of the Drawings
Fig. l is a cross-sectional view of one embodiment of an
interference fit cylinder liner positioned in an engine block
with an attached engine head.
Fig. 2 is a perspective view of an interference fit cylinder
liner.
Detailed Description of the Invention
Referring now to Fig. l, an interference fit cylinder liner
lO is shown positioned in a cylinder block 14 of an internal com-
bustion engine. The internal combustion engine can be of eitherthe gasoline or diesel type and normally includes the cylinder
block 14, a cylinder head 16~ a cylinder head gasket 18 and a
piston 20. The cylinder head 16 is mounted to the cylinder block
14 by a plurality of mounting bolts (not shownl thereby closing
off one end of a cylinder bore 12. As shown, the cylinder head
16 contains a circular pocket 17 having an inner circumferential
surface 19 into which a portion of the interference fit cylinder
liner 10 extends.
The piston 20, which reciprocates within the cylinder
bore 12, is connected in a conventional manner by a connecting
rod 22 to a crankshaft, not shown. Surrounding the circumference
of the piston 20 are a series of piston rings, two of which are
depicted as 24 and 26. These piston rings, 24 and 26, are fitted
to the piston 20 and slidably contact an interior surface 30 of
the cylinder liner lO. The piston rings 24 and 26 serve to seal
in both the combustion gases and the compression pressures pro-
duced in a combustion chamber 28 as well as preventing oil con-
tained in the crankcase from leaking into the combustion chamber
28.
The interference fit cylinder liner 10, which can be either
a wet or a dry liner, is a long hollow cylindrical member open at
both ends as better seen in Fig. 2. This interference fit cylin-
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1 der liner 10 contains a smooth circular interior surface 30 of
substantially uniform diameter and a contour exterior surface 32.
As used through this application, the interference fit cylinder
liner 10 will be described as being in an upright position within
the cylinder block 14. This is strictly for explanation purposes
only and should not be viewed as a limitation since the interfer-
ence fit cylinder liner 10 can also be used in various types of
engines having slanted or horizontally aligned cylinder bores.
At the upper end of the interference fit cylinder liner 10
is a thin wall portion 34 having a circumferential convex cross-
sectional contact surface 36. The shape of thls contact surface
36 can be altered to include a spherical surface or a curved
sector surface. It is preferred that a bowed or geometrically
arcshaped configuration be used in order to obtain a good seal.
The thin wall portion 34, which is preferably resilient within
its elastic limit, can be deflected inward by mounting the cylin-
der head 16 to the cylinder block 14. As the inner circumferen-
tial surface 19 of the cylinder head 16 is forced down over the
thin wall portion 34, an interference fit is established. This
interference fit is also self-energized by the combustion pres-
sures within the combustion chamber 28. As the pressure increases,
due to detonation of the fuel mixture, the thin walled portion is
further forced against the cylinder head 16. This action creates
a tighter seal and is beneficial in preventing combustion gases
from leaking from the combustion chamber 28 to other parts of the
engine. In particular, the interference fit cylinder liner 10
can prevent the leakage of combustion gases in high compression
engines and in high pressure diesel engines. The leakage of such
combustion gases in an engine is detrimental in that it noticeably
affects the engine performance. Starting difficulties, reduced
engine compression and diminished heat transferability by the
engine coolant are but some of the frequently encountered problems.
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1 The interference fit cylinder liner 10 is tightly disposed
in the cylinder block 14 and is vertically retained in position
by a shoulder 38 which abuts a seat 40 of the cylinder block 14.
The shoulder 38 is located on the exterior surface 32 of the
interference fit cylinder liner 10. When the shoulder 38 is in
contact with the seat 40, the thin wall portion 34 will be above
the upper surface of the cylinder block 14. This position is
important because the circular pocket 17 of the cylinder head 16
must fit over the extending thin wall portion 34 and preferably
does not touch a top surface 42 of the interference fit cylinder
liner 10. If the cylinder head 16 contacted the top surface 42,
it could mushroom the interference fit cylinder liner 10, thereby
restricting the reciprocating action of the piston 20. Such
action could also cause the interference fit cylinder liner 10 to
buckle or be deformed out of round, thereby interfering with the
piston 20 and the piston rings 24 and 26~
In addition to the interference fit cylinder liner 10, a
sealing means 44, such as an elastomer ring, can be positioned
between the cylinder block 14 and the cylinder head 16. This
sealing means 44 should contact the exterior surface 32 of the
interference fit cylinder liner 10 just below the thin wall por-
tion 34. This sealing means 44 will provide a backup to prevent
leakage of any combustion gases which may seep past the contact
surface 36. The sealing means 44 can be any high temperature
elastic or rubber-like material. These include prefabricated or
liquid room temperature vulcanizing gaskets such as sold by Dow
Corning or General Electric.
Both the interference fit cylinder liner 10 and the cylinder
head 16 can contain chamfer corners to assist in positioning the
cylinder head 16 over the cylinder liner 10~ Other minor varia-
tions, such as the use of O-ring seals 46 and 48, as shown con-
tacting the lower extremities of the exterior surface 32 of the
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l interference fit cylinder liner 10, can be utiliæed if desired.
Example
For a standard size diesel engine having a peak firing pres-
sure between 3,500-21,000 kilo Pascals, a firing temperature
between 1,500-2,500F and a cylinder bore of approximately 130
millimeters, an interference fit cylinder liner 10 of the follow-
ing dimensions can be used. The interference fit cylinder liner
10 can be approximately 7-10 mm in wall thickness with the thin
wall portion 34 being a millimeter or two less. The interference
fit between the cylinder head 16 and the thin wall portion 34 can
be about .05-.25 mm, preferably .1-.2 mm. The length and diameter
of the interference fit cylinder liner 10 will depend upon the
piston stroke and diameter, The circumferential convex cross-
sectional contact surface 36 can be about 1-2 mm wide and should
be located about 5 mm down from the top surface 42.
While the invention has been described in conjunction with
a specific embodiment, it is to be understood that many alterna-
tives, modifications, and variations will be apparent to those
skilled in the art in light of the aforegoing description.
Accordingly, it is intended to embrace all such alternatives,
modifications, and variations which fall within the spirit and
scope of the appended claims.
