Note: Descriptions are shown in the official language in which they were submitted.
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Description
Unitary Removal of Engine
Cylinder Liner, Piston and Rod
Technical Field
The invention relates to removal of a cylinder
liner, piston, ring and rod from an engine, and more
particularly the invention relates to a method of
removing such engine co,nponents as a unit.
Background Art
Internal combustion engines commonly utilize
cylinder liners to define the bores in which the
pistons reciprocate. During operation of the engine,
the combustion process results in a carbon build-up or
wear step near the top or tne point of piston travel in
tne liner. This and other types of wear usually
necessitate replacement of the cylinder liners and
pistons after a period of time.
Removal of the liners, however, is complicated
by an interference fit between the liners and the
block. The interference fit is established, for
example, by 0-rings about the liners and it generally
increases because of the high temperatures and other
conditions of engine use. Heretofore, a liner without
air inlet ports therethrough has commonly been removed
by inserting a tool down into the bore which may then
be adjusted to grasp the end face of the liner. The
t.
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liner is then pulled from the block by applying
sufficient force on the tool to overcome any
interference fit.
A disadvantage of this practice is that the
piston must first be removed through the top of the
associated cylinder liner so that the tool may be
inserted in the liner. Performing these individual
steps is inconvenient and time consuming, particularly
where the carbon build-up or wear step is pronounced
and must first be removed by grinding in order to the
slide the piston out of the bore.
In two cycle engines where the liners have an
inlet port, it is known to insert into the liner a tool
which has a rod with two ends. Each of the ends are
positioned in opposite ports in the liner, and the
engine rotated to urge the associated piston against
the rod for dislocating the liner. This practice is
described in U.S. Patent 3,805,359 which issued to Webb
on April 23, 1974. U.S. Patent 3,945,104 which issued
to Brookover on March 23, 1976, shows another such tool
in which an impact device is slidable on the tool to
strike an anvil and break the liner loose. It will be
noted, however, that this type of removal practice
still requires separate steps to remove the piston and
rod.
The present invention is directed to
overcoming one or more of the above problems.
Disclosure of the Invention
In one aspect of the present invention, a
method is employed for removing a cylinder liner,
piston, ring and rod as a unit from an engine block.
The method includes inserting a tool in the bore of the
liner, expanding the tool against the liner and
establishing frictional contact between the tool and
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liner. The method further includes applying a force on
the tool and moving the tool with the liner relative to
the engine block, establishing at least a partial
vacuum in the liner above the piston, and then removing
as a unit the liner with the piston, ring and rod.
In another aspect of the present invention, a
method includes inserting a tool having a driver and
mandrel in the bore of the cylinder liner and moving
the piston against and urging the driver into an
aperture of the mandrel. The method further includes
applying a force on the mandrel in the direction of
piston travel and diametrically expanding the mandrel
into frictional engagement with the liner in response
to the driver being urged into the mandrel, and moving
the tool with the liner relative to the engine block.
At least a partial vacuum is established in the liner
above the piston, and the liner together with the
associated piston, ring and rod are removed as a unit.
In still another aspect of the invention, a
tool for removing a cylinder liner from an engine block
has a mandrel and a driver. The driver is insertable
into an aperture of the mandrel. Means is provided for
applying a force on the driver for moving the driver to
a preselected first position in an aperture of the
mandrel.
The cylinder liner, piston and other
associated components are removed as a unit to simplify
engine repair work. Removal as a unit obviates
separate operations which involve first removing the
piston through the liner and then insertion of a tool
to grab the underside of the liner in order to pull the
liner out of the block.
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~rief DescriPtion of the Drawings
Fig. 1 is a diagrammatic view of a portion of
an engine and a tool in place on the engine for
performing an embodiment of the method of the present
invention;
Fig. 2 is similar to Fig. 1, but illustrates
an intermediate step during the disclosed method;
Fig. 3 illustrates in detail the tool shown in
Fig. 1 which may be used to perform a method of the
present invention;
Fig. 4 is a view in cross-section of one
portion of the tool of Fig. 3 taken along line IV-IV of
Fig. 3;
Fig. 5 is a diagrammatic view of an embodiment
of the present invention showing a tool which may be
used to perform a method of the present invention; and
Fig. 6 is a diagrammatic end view in partial
section of the tool of Fig. 5.
~est Mode for Carrying Out the Invention
Referring to Fig. 1, a portion of an internal
combustion engine 10 is disclosed to illustrate a
"cylinder" of the engine. Disregarding for the moment
the tool 12, the engine has a block 14 in an opening of
which is located a cylinder liner 16 forming a cylinder
bore 18 of the engine. The outer surface 19 of the
cylinder liner is sized for a "pilot" fit with the
block opening and has 0-rings 20 positioned in grooves
on a lower portion of its outer surface. When the
liner is fitted to the block, the 0-rings establish an
interference fit on the lower step 24 of the block.
A piston 26 having a top surface 27 and with
rings 28 retained in grooves on its outer surface is
positioned in the cylinder bore 18. The piston
pivotally connects to a rod 32 by conventional means
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which includes a wrist pin 34. The rod is connected to
a crankshaft 37 by use of a rod cap 38. The engine
head (not shownJ fits over the top surface 35 of the
block 14. The construction and operation of such
5 engines are understood in the art and will not be
further explained.
Referring now particularly to Figs. 3 and 4,
an embodiment of a tool 12 which may be employed to
remove a cylinder liner, piston with one or more rings,
10 and rod in their assembled or operational relationship
is shown. The tool is diametrically adjustable such
that it can be inserted into the cylinder bore 18 even
where a carbon build-up or wear step is present on the
liner 16. The tool has two segments 40 which may be
15 described as single-tapered collets with slots 42 such
as are often used to make chucks for holding workpieces
during machining operations. The segments are
constructed of metal with the slots filled or sealed
with an elastomeric or plastic material identified by
20 reference numeral 44. Two tapered arbors 46 are
receivable in tapered openings 47 in the segments 40.
The arbors are of metal construction and each may be
slotted to receive a key for engagement with a slot in
its respective segment. A bolt 48 is positionable
25 through openings in the segments and arbors. One of
the arbors is counterbored to receive the bolt head
(see Figs. 1 and 2). The bolt is also positionable
through openings in a spacer 50 and oversized washer 52
and is at one end threadably engageable with a nut 54.
30 It will be seen that when the tool is assembled and the
nut is turned relative to the bolt, the tapered arbors
will be urged further into their respective tapered
openings causing the segments to expand diametrically.
The tool 12 of Figs. 3 and 4 is shown in Figs.
35 1 and 2 to, as later described, illustrate removal from
the engine 10 of a unit 58 defined to include the
cylinder liner 16, piston 26, rings 28 and rod 32
assembled together in their operational relationship.
Another embodiment of tool 12 is shown in
Figs. 5 and 6. That tool has a mandrel 60 with a
circumferential wall 62. The circumferential wall 62
has an outer surface 64 defining a diameter of the
mandrel and an inner surface 66, at least partly
tapered, defining an aperture 68. The aperture is
shown opening on first and second ends 69,70 of the
mandrel. The mandrel also has a plurality of slots 72
dividing the circumferential wall into segments 74 such
that diametrical expansion of the mandrel tends to
occur in response to forces exerted on the inner
surface. The slots preferably are symmetrically
located and extend substantially the length of the
mandrel so e~pansion will be essentially uniform. The
mandrel also desirably has its outer surface and second
end covered with a flexible, preferably elastomeric,
20 cover 76. A cap 78 having an opening 80 therethrough
is also positionable on the second end of the mandrel.
The tool 12 further has a driver 82 which has
a base 84 and a body portion 86 with tapered walls 88.
The tapered walls extend from the base and define a
frusto-conical shape. The body portion is insertable
into the aperture 68 from the first end 69 of the
mandrel 60. The driver also has an opening 90
therethrough which is at least partly threaded. The
base of the driver extends across the first end of the
mandrel when the body portion is positioned in the
mandrel.
Means 94 is provided for applying a force on
the driver 82 for moving the driver, once inserted into
the mandrel 60, to a preselected position in the
aperture 68 at which the body portion 86 urges against
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the inner surface 66 tending to enlarge the diameter of
the mandrel. The means includes a threaded rod 96 with
a nut 98 and a threaded portion 100 which engages with
the threaded portion of opening 90 of the driver so
that the driver may be "pulled" into position in the
mandrel by progressively tightening the nut against the
cap. It will be seen that the body portion is movable
to succeeding positions in the aperture because the
tapered wall of the body portion will slide along the
tapered inner surface 66 defining the aperture when
sufficient force is applied to the driver. At each
succeeding position the tapered walls of the body
portion will increasingly forcibly urge against the
inner surface tending to define a larger diameter of
the mandrel.
A tool 12 such as illustrated is inserted into
the cylinder bore 18 and expanded against the inner
walls of the cylinder liner 16 (Fig. 1). Expansion
establishes a frictional fit or contact between the
cylinder liner and the outer surface of the tool. For
example, with the tool of Figs. 3 and 4, the bolt 48 is
adjusted to establish frictional forces between the
tool and liner greater than those of the fit of the
liner in the bore 18. The tool of Fig. 5 also
facilitates this practice by adjustment of the nut 98.
Uniform diametrical expansion and metal-rubber
construction, characteristics of the illustrated tools,
substantially eliminate damage to the liner. A force
is subse~uently applied on the tool in a longitudinal
or axial direction relative to the liner. Because of
the frictional fit of the tool with the liner,
sufficient force on the tool "breaks" the interference
fit and the liner will move with the tool from its
position in the engine block 14 (Fig. 2). The liner is
thus removable from the block.
Sufficient force for removal may be applied to
the tool 12 by moving the piston 26 in the bore 18 and
engaging the piston with and urging it against the
bottom of the tool. The piston is moved by rotating
5 the crankshaft 37 with, for example, an engine turning
tool which engages the flywheel in much the same
fashion as the engine starter pinion. The force on the
tool 12 may also be applied on the top of either of the
described tools such as by positioning a bar across and
10 spaced from the top of the tool. The bar, for example,
may be supported by spacers resting on the top surface
35 of the block 14. For the tool of Fig. 3, a rod
passes through an opening in the bar with one end
attached to the tool and the other end threadably
15 engaged by a nut. The nut may be adjusted working
against the bar to raise the rod thereby applying a
lifting force to the tool. For the tool of Fig. 5, the
threaded rod 96 passes through the bar. An additional
nut is tightened against the cap 78 to hold the
20 threaded portion in place in the driver while nut 98 is
adjusted to provide the lifting force. Other devices
may also be used.
The tool 12 of Figs. 5 and 6 also facilitates
removing the unit 58 by using movement of the piston 26
25 to provide both the force for removal and the force for
expansion of the tool. At the outset, the mandrel 60
need only be held against movement in the cylinder
liner 16 with sufficient force to resist the tendency
of the mandrel to slide in the liner as the piston
30 initially moves against the driver. This force may be
established, for example, by use of the threaded rod 96
and nut 98 to diametrically expand the mandrel to a
preselected frictional engagement with the liner.
Thereafter, further piston movement progressively urges
35 the driver into the mandrel to succeeding positions,
:1240127
g
and the mandrel is expanded diametrically thereby
increasing the frictional force holding the tool in the
liner. Simultaneously, a force is also increasingly
exerted on the tool in the direction of piston travel
until the liner breaks loose in the bore 18. For the
above purpose, it is expected that the relative
tapering configurations and other aspects of the
mandrel and driver can be established by one skilled in
the art. Normally, the base 84 against which the
piston urges should be as large as possible to spread
out the forces applied.
For the engine 10 shown, movement of the tool
12 and liner 16 by the piston 26 or other device
applying the force need be only that sufficient to
break the interference fit of the 0-rings 20. In other
engine configurations more tool-liner movement may be
desirable or necessary depending upon the nature of the
interference fit of the liner and engine block 14.
At least a partial vacuum is to be established
in the liner 16 above the top surface 27 of the piston
26 to maintain the unit 58 intact for and during
removal. The tool 12 may be used throughout removal as
an air-tight covering with the vacuum being established
in the liner between the tool and piston. As an
example, expanding the tools shown also establishes an
air-tight fit or contact between the tool and liner to
facilitate forming the vacuum. Alternately, the tool
may be removed to be used on other cylinders or engines
with a cap being put in place on the top of the liner
to act as the air-tight covering. The cap, for
example, may be a plastic plug which simply fits snugly
into the bore 18 and "seals" against the liner's inner
surface. The vacuum is established between the plug
and the piston.
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Experience has shown that conditions for
generating sufficient vacuum may be established by
having the piston 26 in contact or closely adjacent the
tool 12 or cap prior to lifting the liner from the
block 14 (see Fig. 2). The vacuum is established from
the tendency of the piston to move downwardly when the
liner is lifted with the piston, rings 28 and
interconnected rod 32 unsupported.
It should be understood that the disclosed
method may be practiced with additional steps, and that
the order of steps may be varied as evident from the
discussion herein, without departing from the invention.
Industrial Applicability
It is believed removal of the unit 58 from the
engine block 14 is sufficiently clear from the above.
However, a brief discussion follows so that one may
more fully appreciate the advantages of servicing an
engine in the disclosed manner.
Initially, with the head of the engine 10
removed, it is desirable and may even be necessary to
rotate the crankshaft 37 and position the piston 26 at
a de~ired travel point in the cylinder bore 18 to
facilitate positioning the tool and completing the
removal process. The tool 12 is inserted into the bore
preferably far enough such that it will not be over the
carbon build-up or wear step.
Experience will indicate the desired initial
position of the piston for a particular engine and
tool. It is suggested that the piston be positioned
such that, at the time of lifting the liner from the
block, it will be adjacent or in contact with the tool
12, or cap if used, to facilitate establishing the
vacuum. Where the piston 26 is to be used to move the
tool 12 and liner 16, its initial position is
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preferably on the upstroke such that it will be
adjacent or in contact with the tool. This minimizes
the resistance to piston movement from air trapped by
the tool in bore 18 which must leak past the rings.
5 One practice which works well is to insert the tool in
the cylinder bore 18 and rest it on the piston. For
the tool of Fig. 3, the bottom segment 40 would rest on
the piston, while for the tool of Fig. 5, the base 84
of the driver 82 would rest thereon. This permits one
10 to simply rotate the crankshaft 34 to move the piston
and tool to desired positions prior to diametrically
expanding the tool, if necessary, and then to expand
the tool in co~tact with the piston to facilitate the
removal process.
The tool 12 is "expanded" to establish the
frictional fit. The air-tight fit is simultaneously
established without additional "sealing" such that the
tool may be satisfactorily used during the entire
removal process. It may be necessary for sufficient
20 vacuum, however, to use an O-ring at the head of the
bolt 48 in the tool of Fig. 3, or to otherwise prevent
air flow along the bolt. It will be noted that the
bolt head being recessed in the counterbore of the
arbor 46 eliminates piston damage from the bolt head 26
25 and holds the bolt from movement during tool
expansion. Also, the arbors 48 being keyed to their
respective segments 40 prevents relative movement
therebetween. In the tool of Fig. 5, the elastomeric
cover 76 performs the function of sealing to establish
30 the vacuum.
The cylinder liner 16 is next unseated to
break the interference fit by applying sufficient force
to the tool 12 as previously explained. If desired,
the tool may then be removed and used to unseat the
35 next liner on the engine for which a piston 26 is in
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proper position. A cap is fitted in the freed liner so
that the vacuum may be established for completing
removal. Otherwise, the tool is maintained in place.
Next, the rod cap 38 is removed and the liner or tool
where present grasped to pull the liner free of the
block 14. The oversized washer 52 shown with the tool
of Fig. 3 or the eye portion of the tool of Fig. 5, for
example, is a convenient point at which to connect the
tool being used to an overhead device if needed for
lifting purposes. With the partial vacuum, the piston
26, rings 28 and rod 32 will, without being supported,
move free of the engine 10 together with the liner for
removal as the unit 58 .
Other aspects, objects and advantages will
become apparent from a study of the specification,
drawings and appended claims.
