Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2185714
1 VALVE GUIDE INSERT
BACKGROUND OF THE INVENTION
The present invention relates to valve guide
inserts, and in particular to a valve guide insert shaped to
facilitate installation into a valve guide bore.
Valve guides in internal combustion engines can
become worn through extended use. This is especially true
when the valve guide is machined in a cylinder head cast
from iron or other nondurable material. Techniques have
been developed for reaming a worn guide and inserting a
thin-walled, tubular member formed from phosphor bronze or
similar material into the resultant bore to refurbish the
guide.
The first such technique is disclosed in United
'States Patent 3,828,756, issued to James Kammeraad and
assigned to the assignee of the present invention. The
technique includes forming a slitted tubular insert from a
flat sheet of phosphor bronze material and press-fitting the
insert into a reamed valve guide bore. The tubular member
is properly sized so that the slit is substantially closed
when the insert is fitted within the valve guide bore. A
tool is then forced down the insert to work the metal to
further seal the slit and also to form the surface of the
insert contacting the valve stem. In some inserts, spiral
grooves are formed on the surface contacting the valve stem
to provide a path for supplying lubricating oil to the
surface of the reciprocating valve stem.
An improvement to this insert is disclosed in
United States Patent 4,768,479, also issued to James
Kammeraad and assigned to the assignee of the present
invention. This patent teaches preforming on the interior
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1 surface of the thin-walled insert a series of discontinuous
spiral grooves. These grooves act as oil reservoirs,
furnishing oil to lubricate the reciprocating valve stem.
The discontinuous nature of them prevents any tendency of
the oil to flow through the insert into the combustion
chamber.
Use of these thin-walled, phosphor bronze valve
guide liners or inserts has become very popular, commencing
in the early-to-mid-1970s, since they provide improved
durability, improved heat transfer during operation of the
engine, and also since less material needs to be removed
from the engine cylinder head during reboring of the worn
valve guide. The use of thin-walled phosphor bronze inserts
has become so successful, in fact, that they are now being
installed in production engines at the factory to increase
the reliability of the valve guides.
One problem associated with the use of these
thin-walled valve guide inserts is the tendency to crush or
deform during installation. This tendency occurs not only
at the leading end of the insert which is initially being
driven into the valve guide bore, but at the trailing end as
well, since that is where the driving force is applied. The
thinner the insert, the more apt the installer is to
encounter this problem. The preformed discontinuous spiral
on the interior of the insert which is the subject of the
aforenoted United States Patent 4,768,479 has aggravated
this tendency, since the grooves which result from the
removal or displacement of material weaken the sidewalls
even further.
The traditional method of installation compensates
for this tendency to crush or deform by first encapsulating
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1 the insert in an installation sleeve having a funnel-like
opening through which the insert is initially forced to
radially compress it. The insert then traverses into a
section of the installation sleeve which has an inner
diameter basically equal to that of the valve guide bore
into which the insert is installed. The installation sleeve
is then placed over and in alignment with the valve guide
bore, and a punch-like tool used to force the insert from
the sleeve into the valve guide bore. The punch-like tool
has a leading mandrel or pilot having an outer diameter
approximately equaling the inner diameter of the compressed
insert. The driver section of the tool, which is integrally
formed and axially aligned with the mandrel has a
circumferential driving shoulder which flares from the
mandrel at a right angle and has an outer diameter slightly
less than the outer diameter of the.compressed insert and
the inner diameter of the valve guide bore. See Fig. 4 of
United States Patent 3,828,756. The mandrel and
installation sleeve restrain the insert from collapsing
under the force of the driving shoulder. This method of
installation, while effective, is somewhat time-consuming
and requires extreme care on the part of the operator to
insure that the installation sleeve directly overlies the
valve guide bore.
Another prior art method is to bevel or chamfer
the valve guide bore opening, and thus provide a funnel-like
surface to direct the thin-walled insert into the valve
guide bore during installation. The chamfered bore has been
used in conjunction with the installation sleeve of the type
discussed in United States Patent 3,828,756, the chamfer, in
this case, primarily functioning to reduce the degree of
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1 care which otherwise must be taken to insure that the
installation sleeve directly overlies the valve guide bore.
See Hungary Patent Publication 53831, filed May 16, 1989.
The chamfered bore has also been used in conjunction with an
installation sleeve which compresses only the top or driven
part of the insert, the lead end of the insert being
radially compressed by the chamfer and/or by an operator as
the lead end enters the valve guide bore. In either case,
chamfering the bore opening involves an extra manufacturing
step and a special reamer. Also, the chamfering operation
reams away material at the end of the valve guide bore which
ought to be retained, since it supports the valve stem at
the end of the valve guide bore where the lateral forces on
the valve stem are most pronounced. Compounding this
'prpblem is the fact that many chamfering operations are not
well controlled, leading to excessive material being
removed.
. The present disclosure provides a valve guide
insert for valve guides of internal combustion engines and
the like, which is capable of insertion into a valve guide
bore having a nonchamfered opening. The valve guide insert
includes a thin-walled, generally cylindrically-shaped,
metallic tube having ends. At least a section of the insert
central to the ends has an outer diameter substantially
equal to or slightly greater than the inner diameter of the
valve guide bore within which the insert is to be installed,
such that the insert, when positioned within said bore, will
be retained by a press fit. The central section of the
3o insert has an inner diameter about equal to or slightly
greater than the diameter of the valve stem which is to
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1 reciprocate therein, the inner and outer diameters of the
central section defining the approximate desired wall
thickness of the insert when installation and reworking are
complete.
At least one of the ends of the insert has a
reduced inner diameter and a reduced outer diameter relative
to the central section providing a tapered insertion section
adapted to lead the insert into said bore. The tapered
insertion section has a wall thickness substantially equal
to or greater than the wall thickness of the central
section, such that the tapered insertion section will not be
prone to crush during .installation of the insert into the
bore. According to a preferred embodiment of the
invention, the wall thickness of the tapered insertion
,section is such that when the tapered insertion section is
reworked after installation of the~insert into the bore to
bring the inner diameter thereof substantially equal to the
inner diameter of the central section, the outer diameter of
the tapered insertion section will be substantially equal to
the outer diameter of the central section.
In a narrower aspect, the valve guide insert
comprises a thin-walled, generally cylindrically-shaped,
metallic tube made of resilient material with a slit along
its length, the insert being sprung open slightly but
compressible to close the slit and to form the outside
diameter of the central section to be press-fit into the
valve guide bore. In the preferred embodiment, the valve
guide insert is made of phosphor bronze of about 0.018 inch
thickness or less.
Another aspect of the present disclosure comprises
a tool for inserting the above-noted valve guide inserts
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into a valve guide bore. The tool includes a mandrel or
pilot section and a driver section, the sections being
interconnected by a frusto-conical junction. The driver
section includes, adjacent the base of the frusto-conical
junction, a circumferential, square driving shoulder
adapted to engage and drive the bore-remote extremity of
the insert. The frusto-conical junction is adapted to
flex the taper from the valve guide bore-remote tapered
insertion section on the valve guide insert. This flexing
is accomplished within an installation sleeve having an
inner diameter sufficiently large to accommodate the
driving shoulder which is somewhat larger in diameter than
the valve guide bore.
Another aspect of the present disclosure provides a
process for making a valve guide insert having ends with
tapered insertion sections.
In accordance with a first aspect of the invention
there is provided, a valve guide insert for lining and
relining a valve guide of an internal combustion
engine, the engine including a valve having a valve
stem which is to reciprocate in the bore of the valve
guide, comprising:
a thin-walled, generally cylindrically shaped,
metallic tube having ends and a section intermediate to
the ends, said intermediate section having an outer
diameter substantially equal to or slightly greater
than the inner diameter of the valve guide bore within
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which said insert is to be installed so that said
insert, when positioned within said bore, will be
retained by a press fit, said intermediate section of
the insert having an inner diameter about equal to or
slightly greater than the diameter of the valve stem
which is to reciprocate therein, the inner and outer
diameters of said intermediate section defining the
approximate desired wall thickness of said insert when
installation is complete; and
at least one of said ends having a reduced inner
diameter and a reduced outer diameter relative to said
intermediate section, said at least one end providing a
tapered insertion section adapted to lead said insert
into the valve guide bore, said tapered insertion
section having a wall thickness substantially equal to
or slightly greater than the wall thickness of said
intermediate section such that said tapered insertion
section will not be prone to crush during installation
of said insert into the bore, whereby said insert can
be installed in a valve guide bore Having a
nonchamfered opening.
In accordance with a second aspect of the
invention there is provided a method for lining and
relining a valve guide bore of an internal combustion
engine comprising:
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providing an engine component including material
defining a valve guide bore and an opening to the valve
guide bore, the material defining the opening to the
- valve guide bore including a generally square lip;
providing a thin-walled valve guide insert
including an intermediate section and at least one end
having a reduced inner diameter and a reduced outer
diameter relative to the intermediate section defining
a tapered insertion section, the tapered insertion
section and the intermediate section defining a
substantially continuous wall thickness;
providing an installation tool for the valve guide
insert, the installation tool having a mandrel section
constructed to be inserted into said valve guide
insert;
placing the valve guide insert onto the mandrel
section of the installation tool;
aligning the valve guide insert with the valve
guide bore by inserting the tapered insertion section
of the one end of the valve guide insert partially into
the valve guide bore with the tapered insertion section
contacting the generally square lip of the valve guide
bore; and
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driving the valve guide insert into press-fit
engagement with the valve guide bore by use of the
installation tool, whereby the valve guide insert can
be inserted into the valve guide bore past the
generally square lip without being prone to crush
during installation of the valve guide insert into the
valve guide bore.
In accordance with a third aspect of the invention
there is provided, a process for forming a valve guide
insert for lining and relining a valve guide bore of an
internal combustion engine, comprising the steps of:
providing thin-walled flat stock having opposing
edges and a wall thickness of up to about 0.018 inches;
forming the flat stock into a cylindrical tube,
the cylindrical tube defining ends corresponding to the
opposing edges; and
crown forming a tapered insertion section having a
reduced inner diameter and a reduced outer diameter on
at least one of said ends, said step of crown forming
the tapered insertion section including forming the at
least one of said ends before, after, or concurrently
with the step of forming the flat stock into the
cylindrical tube.
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In accordance with a fourth aspect of the
invention there is provided, a process for forming a
- valve guide insert for lining and relining a valve
guide bore of an internal combustion engine, comprising
the steps of
providing flat stock having opposing edges and
made of phosphor bronze material;
forming the flat stock into a cylindrical tube
having a wall thickness of up to about 0.018 inches;
forming a tapered insertion section having a
reduced inner diameter and reduced outer diameter on at
least one end, said step of forming the tapered
insertion section including forming the at least one
end before forming the flat stock into the cylindrical
tube or forming the at least one end after forming the
flat stock into the cylindrical tube; and
crown forming both of the ends to form a tapered
insertion on both of the ends.
In accordance with a fifth aspect of the invention
there is provided, a process for forming a valve guide
insert for lining and relining a valve guide bore of an
internal combustion engine, comprising steps of:
providing flat stock having opposing edges and
made of phosphor bronze metal;
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forming the flat stock into a cylindrical tube
having a wall thickness of up to about 0.018 inches,
_ the cylindrical tube defining ends corresponding to the
opposing edges; and
forming a tapered insertion section having a
reduced inner diameter and a reduced outer diameter on
at least one of said ends, said step of forming the
tapered insertion section including forming the at
least one of said ends before forming the flat stock
into the cylindrical tube or forming the at least one
of said ends after forming the flat stock into the
cylindrical tube wherein the step of forming the
tapered insertion section is done simultaneously with
the step of forming the flat stock into a cylindrical
tube, and includes progressively stamping the flat
stock.
The embodiments of the invention will now be
described with reference to the accompanying drawings
wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side-elevational, cross-sectional view
of a value guide insert shown as installed in a valve
guide bore of an engine cylinder head;
Fig. 2 is a perspective view of the valve guide
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insert shown in Fig. 1 before installation;
Fig. 3 is a side cross-sectional view of the valve
guide insert shown in Fig. 2 but with the insert being
radially compressed to close the slit;
Fig. 4 is a fragmentary side view of the valve
guide insert shown in Fig. 2 positioned adjacent and in
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. 2185714
1 alignment with a valve guide bore and ready for insertion
therein;
Fig. 5 is a side cross-sectional view illustrating
the valve guide insert partially inserted into the valve
guide bore by a tool shown in Figs. 8-lI, the clearances
being emphasized for illustrative purposes;
Fig. 6 is a partial side cross-sectional view of a
second value guide insert;
Fig. 7 is a partial side cross-sectional view of a
third valve guide insert;
Fig. 8 is a side view of the driving member of a
tool embodying the invention used for inserting the valve guide
insert shown in Fig. 2 into a selected valve guide bore;
Fig. 9 is a side cross-sectional view of the tool
,far- installing a valve guide insert, the tool shown with a
valve guide insert being held thereon ready for insertion
into a valve guide bore:
Fig. 10 is an enlarged view of a portion of Fig. 9
with clearances being emphasized for illustrative purposes;
Fig. 11 is a fragmentary side cross-sectional view
of the valve guide insert after insertion of the valve guide
insert into the valve guide bore by the tool shown in Fig.
9;
Fig. 12 is a flow chart illustrating the steps of
installing a valve guide insert into a valve guide bore;
Figs. 13-15 are side cross-sectional views of
three embodiments of the guide insert blank material after
forming the edge portions thereof while the blank material
is substantially flat and before forming the cylindrical
shape of the insert;
218~7~~
1 Fig. 16 schematically illustrates a process
including use of a set of progressive forming dies for
forming the guide valve insert blank material into the
cylindrical shape of the valve guide insert;
Fig. 17 schematically illustrates roll-forming
rolls for forming the edges of the guide valve insert
material before use of the forming dies in Fig. 16;
Fig:' 18 is a side cross-sectional view of an
internal center pin and forming block for forming the ends
of the valve guide insert; and
Fig. 19 is a side cross-sectional view of an
external center pin and forming block for forming the ends
of the valve guide insert.
. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings and to Fig. 1 in
particular, a valve guide insert 10 is shown, insert 10 being
adapted for insertion into a nonchamfered valve guide bore 12 of an
overhead cylinder head 14 for an internal combustion engine (not
shown). Insert 10 is adapted for use in a cylinder head 14
with a valve guide bore 12 machined therein (Fig. 1).
Cylinder head 14 includes an exposed shoulder portion 32
located at one end of valve guide bore 12. Ordinarily, the
exposed shoulder 32 will be integrally cast with head 14 and
thereafter machined to proper dimensions. A valve stem 34
of valve 33 is passed through valve guide bore 12 during
assembly. A valve spring 36 encircles exposed shoulder
portion 32 of the valve guide assembly, and valve 33 is
conventionally retained with respect thereto by a pair of
valve keepers (not shown). Valve stem 34 extends downwardly
and terminates in a valve flange 38 adapted to seat against
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1 a valve seat 40. A suitable valve seat 40 is machined into
the lower surface of cylinder head 14. The valve opens into
an engine combustion chamber (not shown). Valve spring 36
retains the valve in a closed position with respect to seat
40 except when forced downwardly by a rocker arm (not shown)
or the like in proper operational sequence.
Valve guide insert 10 (Fig. 2) is a thin-walled,
cylindrically-shaped, metallic tubular member made of
phosphor bronze material, and includes a slit 18 extending
lengthwise from end 20 to opposing end 22 so that the insert
can be radially compressed and press-fit into valve guide
bore 12. Insert 10 includes tapered insertion sections 24,
26 formed inwardly at ends 20, 22 to facilitate insertion of
insert 10 into a nonchamfered valve guide bore 12 having a
square lip 28 (Fig. 1). Due to the thinness of the walls of
insert 10, the ability to introduce insert 10 into valve
guide bore 12 without abutting lip 28 or otherwise
interfering with the leading end 20 as insert 10 enters
valve guide bore 12 is particularly important in order to
avoid undesirably crushing or deforming insert 10. To this
end, the wall thickness is maintained throughout the length
of the insert, including at the tapered insertion sections
24, 26. This constant or near-constant wall thickness
preserves the structural integrity of tapered insertion
Sections 24, 26, discouraging crushing or deforming during
installation. This constant or near-constant wall thickness
also permits the insert to be reworked after installation to
bring its inner diameter (approximating the diameter of the
valve stem to reciprocate therein) and its outer diameter
(slightly greater than the inner diameter of the valve guide
bore 12) equal throughout its length as shown in Fig. 1.
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1 Full wall thickness at the extremities is important, since
these are typically the areas which will wear first.
Valve guide insert 10 (Figs. 2 and 3) is adapted
to be press-fit within valve guide bore 12 so that slit 18
is substantially closed after insert 10 is installed. Slit
18 is bounded by first and second offset edges 42 , 44 which
are preformed in a blank of flat stock before the tubular
shape of the insert is formed. The dimensions of the flat
stock are selected such that, after the insert is fitted
into the valve guide bore 12, slit 18 will be closed. The
blank is chosen with a particular thickness T and width to
form diameters D1 and D2. Diameter D1 is chosen for the
particular valve guide bore within which the insert is to be
installed, and diameter D2 is chosen so that it can be
'broached or otherwise worked to an inner diameter for
receiving the particular valve stem 34 desired. Diameter
D2, of course, must be such as to require that the insert be
press-fit into the bore and retained therein, at least in
part, by a tendency to radially expand. It is contemplated
that this wall thickness T can be any thickness desired, but
is preferably between about .010 and .025 inch, and most
preferably about .015 to .018 inch. A thinner wall thick-
ness T promotes improved heat transfer, as noted below.
Valve guide insert 10 includes a first finger
member 46 and a second finger member 48 defined by over-
lapping transverse edge portions 50, 52. Overlapping
transverse edge portions 50, 52 inhibit oil flow along the
seam 18 and also prevent skewing or twisting as the insert
10 is press-fit into valve guide bore 12. Valve guide
insert 10 also includes multiple offset spiral grooves 54
that retain oil along the interior length of insert lo. For
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1 further information on the general construction of such an
insert, reference is made to aforenoted United States Patent
3,828,415, issued August 13, 1974, entitled METHOD AND
APPARATUS FOR REBUILDING VALVE GUIDES; United States Patent
4,103,662, issued August 1, 1978, entitled INSERT FOR
REBUILDING VALVE GUIDES; and United States Patent 4,768,479,
issued September 6, 1988, entitled OIL-SEALING VALVE GUIDE
INSERT AND METHOD OF MANUFACTURE.
It is believed that grooves 54 affect the ease
with which insert 10 can be press-fit into valve guide bore
12 in at least two ways. Grooves 54 somewhat weaken the
sidewalls of the insert 10, rendering the insert more prone
to accordion-type collapse during the press-fitting
,operation. Also, grooves 54 affect the wall structure in a
way that increases the frictional resistance to insertion.
This is evidenced by the increased retention strength of
inserts having grooves over comparably-sized inserts without
grooves. For example, experimental test data has shown that
the retention strength of an insert with grooves installed
in a valve guide bore is about 20-50% or more above the
retention strength of a comparable insert without grooves.
The novel insert here described can be
installed with relative ease, whether or not it includes the
oil-retaining grooves 54. To this end, the liner is
provided at either end with a tapered insertion section 24,
26. A number of different geometric configurations-are
contemplated for this tapered insertion section. In insert
10 (Fig. 3), tapered insertion sections 24, 26 have
arcuately-shaped outer tapered surfaces 56, 58. In another
embodiment, an insert 10' (Fig. 6) includes tapered
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1 insertion sections 24', 26' having sonically-shaped outer
tapered surfaces 56', 58'. In still another embodiment, an
insert 10" (Fig. 7) includes tapered insertion sections 24",
26" having stepped outer surface 56", 58" with fore-
shortened, sonically-shaped wall portion 56A" and a
cylindrically nontapered terminal tip portion 56B":
In each of the inserts 10, 10' and 10", the wall
thickness T is substantially maintained throughout the
length of the tapered insertion sections. This is important
for two reasons. First, the tapered insertion sections take
the brunt of the press-fitting forces at both the valve
guide bore entry point and at the force application point.
The constant or near-constant wall thickness, in this
regard, insures that the tendency to crush at these
locations will be minimized during press-fitting
installation. Second, this constant or near-constant wall
thickness permits the insert to be reworked by broaching or
the like, after being press-fit into bore 12, so that the
insert will have a generally constant wall thickness
throughout its length. This insures maintenance of the
structural integrity of end sections 24, 26, since it is at
end sections 24, 26 where the greatest support for
reciprocating valve stem 34 is required.
Inserts 10, 10' and 10" advantageously can be
readily installed into a valve guide bore 12 having a square
lip 28. As shown in Fig. 4, end 20 of tapered insertion
section 24 of insert~l0 fits partially into valve guide
opening 30 as defined by lip 28. Insert 10 is then urged
fully into valve guide bore 12 with the walls of insert 10
following insertion section 24 into valve guide bore 12
(Fig. 5).
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1 Once fully inserted therein, the inside diameter
of insert 10 is reworked by broaching to accurately form the
inside diameter so that insert 10 as installed can properly
receive reciprocating valve stem 34 (Fig. 12). The
broaching process also reduces or eliminates air pockets
between insert 10 and valve guide bore 12, thus improving
heat transfer by reducing hot spots during operation of the
engine. Broaching, as noted, also reforms the tapered
insertion sections 24, 25 outwardly so that they assume the
configuration of Fig. 1, having a generally constant inner
and outer diameter throughout their length and being in
intimate contact with the walls of bore 12 throughout their
length. A broaching process and tool suitable for these
purposes is disclosed in United States Patent 4,573,340,
'issued March 4, 1986, entitled VALVE GUIDE LINER BROACH AND
TOOL. Inserts 10' and 10~~ can be similarly inserted.
Insert 10 (Figs. 2-3) includes identical tapered
insertion sections 24, 26, tapered inwardly at ends 20, 22,
respectively, to present inwardly tapered surfaces 56, 58,
respectively. It is contemplated that only one end of
insert 10 need have the tapered portion. However, by
tapering both ends, an operator using insert 10 need not be
concerned with aligning the wrong end of the insert adjacent
valve guide bore opening 30. It is also contemplated that
the insertion section will be about 1/8 of an inch long,
though other sizes can be used. The tapered insertion
section, as will be pointed out in detail, permits use of an
installation slee~ie 72 having a diameter greater than that
which could otherwise be used. This greater diameter, in
turn, permits use of an installation tool 68 which
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1 automatically compensates for the taper at the bore-remote
extremity during the press-fitting installation.
This installation tool 68 (Figs. 8-11) includes an
elongate driver member 70, and an insert installation sleeve
72 which fits over the end of elongate driver member 70 and
holds insert 10 thereon. Driver member 70 includes an
elongated mandrel or pilot section 74 in the shape of a rod,
an elongated driver section 76 which is also rod-like and
axially extends from mandrel 74, and a shank 77 mounted to
the rearward end of driver section 76.
Mandrel 74 includes a beveled leading end 78 to
assist in placing insert 10 thereonto. The body 80 of
mandrel 74 can be longer or shorter than the insert 10 which
it supports. In the illustrated example (Fig. 9), mandrel
74..is shorter than insert 10. Thus, formed end 24 extends
outwardly beyond mandrel 74 as shown in Fig. 9. Due to the
axial and radial strength of insert 10, this has not been a
problem during installation of the illustrated insert 10.
Mandrel 74 tapers outwardly in frusto-conical
fashion as indicated at 82 at.its junction with driver
section 76. Driver 76 includes a circumferential, square
driving shoulder 84 adjacent the widest part of junction 82.
Driving shoulder 84 is adapted to contact tapered insertion
section 26 of insert 10 and drive insert 10 into valve guide
bore 12. Outwardly tapered frusto-conical junction 82
begins about .25 inch or less from the face or driving
shoulder 84 of driver'section 76 and extends rearwardly at
an angle of about 5° or less.
Shank 7'7~ is axially aligned and integrally
interconnected to mandrel 74 and driver section 76. Shank
77 includes front and rear enlargements 86, 88, with a
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1 protrusion 90 extending rearwardly from rear enlargement 88,
Protrusion 90 provides a means for gripping and driving
elongate driver member 70 such as by an impact gun (not
shown), while enlargements 86, 88 provide an area for
grasping and aligning installation tool 68 with a selected
valve guide bore 12.
Installation sleeve 72 (Figs. 9, 10 and 11) of
installation tool 68 is a cylindrically-shaped member with a
bore 73. Sleeve 72 is slidingly positioned over driver
section 76 and mandrel 74 of driving member 70.
Installation sleeve 72 includes an enlarged midsection 92
for ease of grasping and an elongated tubular section 94.
Midsection 92 includes a necked forward portion 93 with
bore-abutting face 95. Necked portion 93 provides clear-
anees for casting interferences around valve guide bore 12
as installation tool 68 is used to press-fit insert 10 into
valve guide bore 12, while front face 95 abuts lip 28 as
insert 10 is press-fit into valve guide bore 12 (Fig. 11).
Installation sleeve 72 also includes a rearward end 102 on
tubular section 94 that is adapted to abut a forward end 104
of shank 77, as described below.
A coil spring 96 is positioned around tubular
section 94 of installation sleeve 72. The ends of spring 96
are retained by a first depression 98 on tubular section 94
adjacent enlarged midsection 92 and by a second depression
100 on front enlargement 86. Spring 96 biases installation
sleeve 72 forwardly on driver member 70 to a position
partially on mandrel 74 of driver member 70. Installation
sleeve 72 has a length about equal to driver section 76. As
insert 10 is press-fit into valve guide bore 12 (Fig. 11)
and reaches the desired home position, the rearward end 102
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1 of installation sleeve 72 abuts the forward end 104 of shank
77. Thus, installation tool 68 automatically sets or
controls the desired depth of the insert in valve guide bore
12.
As insert 10 is positioned on mandrel 74, junction
82 flexes the taper from tapered insertion section 26,
permitting square driving shoulder 84 to apply a
longitudinal, as opposed to a crushing, force on section 26,
thus driving the insert into the valve guide bore. The
outside diameter of mandrel body 80 is slightly less than
diameter D2 of liner 10. The inner diameter of installation
sleeve 72 is slightly greater than diameter D1 of insert 10.
The two diameters (of mandrel body 80 and installation
sleeve 72) are selected so as to provide clearance for
frusto-conical function 82 as well as adequate support for
liner 10 during installation as noted below. The relative
ease with which the insert can be forced into the valve
guide bore as a result of the provision of tapered insertion
section 24 permits the diameter of installation sleeve 72 to
be enlarged relative to previous installation sleeves, thus
. accommodating the increased diameter of junction 82 within
the sleeve.
To facilitate understanding of the invention
herein, the following example gives specific dimensions
illustrating one particular installation tool 68 for
installing a particular valve guide insert 10 in a
particular rebored valve guide bore 12: _-
EXAMPLE
Initially the exemplified valve guide 12 is
rebored to a maximum diameter of about .3735 inches. A
liner 10 is then chosen for installation in the valve guide
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21~~71~
1 to bring the valve guide bore diameter to an inner diameter
of about .3438 inches (i.e. 11/32 of an inch) for receiving
a particular valve stem 34. Specifically, liner 10 is
chosen with a wall thickness of about .016 inches and an
outer diameter larger than .3438 inches so that the inner
diameter of the liner after being press-fittingly installed
in valve guide bore 12 is about .3415 inches (before
broaching). This allows the inner diameter of the installed
insert to be later broached to the desired valve guide bore
diameter of .3438 inches, with at least .001 of phosphor
bronze material being moved by the broaching process. Liner
10 is chosen with a length as needed to fill valve guide
bore 12, which in this example is about 2.250 inches.
An appropriate tool 68 is chosen for installing
tha particular liner 10 noted above. In the given example,
the diameter of mandrel 74 of driver member 70 is about .328
inches and the length about 2.00 inches. Notably, the
length could be longer than insert 10 if desired. Outwardly
tapered junction 82 of the chosen driver member has a
maximum dimension of about .348 inches, and driver section
76 has an outer diameter of about .384 inches. Thus, driver
shoulder 84 has a width of about .018 (i.e. total width
dimension of .036 inches including both sides). Insert
installation sleeve 72 has an inner diameter of about .386
inches, and a length equal to the distance from driver
shoulder 84 to the forward end 104 of shank 77, which
distance is about 1.250 inches in the present example.
The selected liner 10 is placed on mandrel 74 so
that insertion section 26 rides up onto outwardly tapered
junction 82 to create an outer diameter at driver shoulder
84 of about .380 inches (i.e. the maximum dimension .348
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2185714
1 inches of junction 82 plus two wall thicknesses .016 of
insert 10). As insertion sleeve 72 is slid forwardly from
driver section 76 telescopingly onto insert l0, the taper is
removed from tapered insertion section 26 of liner 10 and
tapered insertion section 26 is forced to a substantially
longitudinally aligned position with the length of liner 10.
Also, liner 10 is held in a radially compressed condition so
that slit 18 is closed or near closed. Due
to the rigidity of the phosphor bronze material, slit 18 is
closed or near closed even along the part of insert l0 which
hangs outwardly from insertion sleeve 72 on mandrel 74.
Thus, insert 10 is held at an outer diameter of about .386
inches along its length which notably is slightly greater
than rebored valve guide bore 12 which has a diameter of
about .3735 in this example. However, tapered insertion
section 24 forms an inwardly tapered end that is adapted to
ramp into nonchamfered opening 30 of rebored valve guide
bore 12, as noted above and illustrated in Figs. 4, 5 and
11. As junction 82 enters valve guide bore 12 during
installation of insert 10 into bore 12, the junction 82 and
insert 10 combine to form a maximum diameter of .380. Since
valve guide bore 12 is only .3735 in diameter, this creates
an interference at lip 28 of valve guide bore 12. However,
this interference does not create a problem due to the short
length of junction 82, which is only about .250 inches or
less, and the low angle of junction 82, which is only about
5° or less.
As noted previously, the dimensions in the Example
are given only to facilitate an understanding of the
invention herein and are not to be limited by them.
By way of comparison, for a chamfered valve guide bore of
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218571
1 similar size to the valve guide in the example, prior known
tools used by the assignee of the present application would
most likely have a continuous outer diameter on the mandrel
of about .338, no tapered junction, and a continuous outer
diameter on the driver section of about .378 inches. The
prior sleeve holder would have an inner diameter of about
.381 inches.
Insert 10 can be manufactured in a number of
different ways. As illustrated in Fig. 16 the insert
material is first uncoiled from a coil of stock in
step 112, and spiral grooves 54 are formed in
,the material in step 113 such as is disclosed in the
aforenoted United States Patent 4,185,368. Insert blanks
are then stamped from the uncoiled stock in step 114 and the
general contour of end portions 24, 26 are formed along the
edges of the guide insert material in step 115.
Configurations 116, 118, 120 can be formed a number of
. different ways, such as by stamping, roll-farming and other
bending methods.
Three configurations of blanks formed in step 115
are illustrated in Figs. 13-15. Fig. 13 illustrates a
radiused insertion section 116, while Fig. 14 illustrates an
angled insertion section 118, and Fig. 15 illustrates a
stepped insertion section 120. These configurations 116,
118 and 120 correspond to inserts 10 (Fig. 3), insert 10~
(Fig. 6) and insert 10~~ (Fig. 7), respectively. F-iowever, it
is contemplated that a variety of different configurations
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2185~1~
1 of tapered insertion sections can be formed and still be
within the broader aspects of the inventions herein.
As shown in Fig. 16, a form fixture 110 is used to
form the tubular shape of insert 10 (or insert 10' or 10").
Presently, two strikes of the forming dies are used to fully
form the cylindrical shape of insert 10, although it is
contemplated that more or less can be used, or that sizing
dies can be used if necessary to properly shape insert l0.
In Fig. 16, angled lips 121 are used to represent the
to position of tapered insertion sections 24, 26 during the
forming process.
It is contemplated that roll-forming roller pairs
124 (Fig. 17) including an upper roller 126 and a lower
roller 128 can be used to perform step 115 and form edge
portions 116, 118, 120. Notably, roll-forming rollers 126,
128 can be used to form ends 116, i18, 120 on guide insert
material either before or after the uncoiled material is cut
into blanks in step 114.
Fig. 18 illustrates another method of forming
tapered insertion sections 24, 26. In Fig. 18, a guide
insert with a continuous diameter is supported from within
by a center pin 130. Center pin 130 has a midsection 132
with a large diameter for supporting the length of insert
10" at the inner diameter D2, and also includes a tip
section 134 having a reduced diameter for supporting the
inside of tapered insertion sections 24", 26" during the
forming process. To form insert 10", forming blocks 136,
138 are closed onto a cylindrically-shaped insert with
center pin 130 therein. A forming block or crowning block
140 is then pressed onto the tip section 134 of pin 130 to
form tapered insertion sections 24", 26". Forming block 140
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21~~7~4
1 includes a shaped bore 142 that engages the ends of the
insert and tip section 134 to crown the end of insert 10"
and form tapered end portions 24", 26'!~: Notably, insert 10"
includes slit 18 allowing insert l0" to spring open slightly
as pin 180 is axially removed from'insert 10". It is
contemplated that forming block 140 can be used
simultaneously with form fixture li0 (Fig. 16) or can be
used separately in a subsequent step.
Another method is illustrated in Fig. 19. This
embodiment includes features similar to the embodiment shown
on Fig. 18, and comparable components are denoted by a
numeral with a prime following the number. In this
embodiment, an end forming pin 144 is extended partially
into an end of a cylindrically-shaped insert and forming
1~ block 140' is introduced against the end of partially formed
.,
insert 10" and against closed forming blocks 136', 138'. As
forming block 140' crowns the end of insert 10", material is
forced toward pin 144 thus forming tapered insertion
sections 24", 26". Though only insert 10" is shown in Figs.
16-19, it is contemplated that any of inserts 10 or 10' can
be formed by these processes, and the particular devices
shown are for illustration only.
Having described insert 10 and variations thereof,
and installation tool 68 and also the process of forming
inserts, the uses and advantages
will become apparent to one of ordinary skill in the art.
Initially, insert 10 is formed by one of the aforementioned
processes utilizing generally standardized manufacturing
equipment to form coiled strip stock of phosphor bronze into
inserts 10. Multiple of these inserts are made with
particular thicknesses T, the inserts being radially
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2185'1 ~
1 compressible to close slit 18 and form particular diameters
D1 and D2 which are desired.
Once formed, an insert 10 of desired size and
configuration is selected and inserted onto mandrel 74 of a
properly-sized driver member 70 with tapered insertion
section 26 riding up onto outwardly tapered junction 82
(Fig. 9). Installation sleeve 72 is initially held over
driver section 76 with spring 96 compressed as insert 10 is
inserted onto mandrel 74. Installation sleeve 72 then
slides downward from driver section 76 to partially overlie
mandrel 74 and to partially overlie insert 10. In
particular, installation sleeve 72 slides over tapered
insertion section 26. As insert 10 is positioned on mandrel
74, junction 82 flexes the taper from tapered insertion
section 26, permitting square driving shoulder 84 to apply a
--
'longitudinal force on section 26 for driving the insert into
the valve guide bore.
With insert 10 thus held by installation sleeve 72
on driver member 70, insert 10 is ready to be installed.
Insert 10 is first aligned with valve guide bore 12 (Figs. 4
and 5), with leading tapered insertion section 24 placed
within the bore 12. Driver 70 is then driven downwardly
with an impact gun (not shown) or the like. Flat driving
surface 84 engages end 22 of insert to (Fig. 5) and drives
insert l0 into place. Installation sleeve 72 slides
upwardly on driver section 76 of shank 68 until it abuts the
face 104 of shank 68.' Thus, insert 10 is slidingly
installed in a press-fit condition into valve guide bore 12
at a predetermined depth (Fig. 11). Driving member 70 is
then withdrawn and another insert 10 is placed thereon. The
sequence is then repeated.
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a
1 Once all inserts are in place, each is reworked
such as by broaching to bring the insert into the
configuration shown in Fig. 1. This reworking process
insures not only that the insert will be seated fii-~nly
within the bore 12, but that its wall thickness will be
constant or near-constant throughout its length.
Changes and modifications in the specifically
described embodiments can be carried out without departing
from the scope of the invention which is intended to be
limited only by the scope of the appended claims.
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