U.S. patent application number 10/308696 was filed with the patent office on 2004-06-03 for valve stem seal assembly.
This patent application is currently assigned to DANA CORPORATION. Invention is credited to McArthy, Troy D..
Application Number | 20040104537 10/308696 |
Document ID | / |
Family ID | 32392814 |
Filed Date | 2004-06-03 |
United States Patent
Application |
20040104537 |
Kind Code |
A1 |
McArthy, Troy D. |
June 3, 2004 |
VALVE STEM SEAL ASSEMBLY
Abstract
A valve stem seal assembly incorporates a cylindrical retainer
having an axis and an upper end about which symmetrically and
circumferentially arranged, alternating first and second sets of
fingers have radially inwardly depending upper ends. The first set
of fingers is generally parallel to the axis and the upper ends are
generally perpendicular to the axis to engage a first exterior
annular groove of an elastomeric seal body. The first set of
fingers provides for axial attachment of the seal body to a top of
a valve guide. The second set of fingers is generally arcuate and
the upper ends extend radially inwardly to engage a second exterior
annular groove of the seal body. The second set of fingers
eliminates the need for a garter spring used by traditional valve
stem seal assemblies by generating a force to urge the sealing lip
against a reciprocating valve stem.
Inventors: |
McArthy, Troy D.; (Auburn,
IN) |
Correspondence
Address: |
RADER, FISHMAN & GRAUER PLLC
39533 WOODWARD AVENUE
SUITE 140
BLOOMFIELD HILLS
MI
48304-0610
US
|
Assignee: |
DANA CORPORATION
|
Family ID: |
32392814 |
Appl. No.: |
10/308696 |
Filed: |
December 2, 2002 |
Current U.S.
Class: |
277/502 |
Current CPC
Class: |
F01L 2301/00 20200501;
F01L 3/08 20130101; F02F 11/002 20130101 |
Class at
Publication: |
277/502 |
International
Class: |
F02F 011/00 |
Claims
What is claimed is:
1. A valve stem seal assembly adapted for installation atop of a
valve guide of an internal combustion engine for sealingly engaging
a valve stem reciprocally moveable through the valve guide, the
seal assembly comprising: a resilient annular seal body defining an
interior annular sealing lip adapted to engage the valve stem and
further including a first exterior annular groove and a second
exterior annular groove; a retainer defining a generally rigid
cylindrical body having an axis and including an upper body end and
a lower body end; a first set of fingers disposed from said lower
body end of said retainer and comprising radially inwardly
depending upper ends for engaging said first exterior annular
groove of said seal body to maintain said seal body axially against
a top surface of the valve guide; and a second set of fingers
disposed from said lower body end of said retainer and comprising
radially inwardly depending upper ends for engaging said second
exterior annular groove of said seal body to impart a
circumferential force to said sealing lip and to urge said sealing
lip against the reciprocally moveable valve stem.
2. The valve stem seal assembly, as in claim 1, wherein said second
set of fingers has a different length than said first set of
fingers.
3. The valve stem seal assembly, as in claim 1, wherein said first
set of fingers are generally parallel to said axis of said retainer
and said upper ends of said first set of fingers are generally
perpendicular to said axis for engaging said first exterior annular
groove of said seal body.
4. The valve stem seal assembly, as in claim 1, wherein said second
set of fingers are generally arcuate over the length of the fingers
resulting in said upper ends of said second set of fingers engaging
said second exterior annular groove of said seal body.
5. The valve stem seal assembly, as in claim 1, wherein said seal
body further comprises a lower circumferential flange defining a
bottom surface adapted to sealing engage the top surface of the
valve guide.
6. The valve stem seal assembly, as in claim 1, wherein said first
and second sets of fingers are circumferentially alternating, such
that each finger of said first set of fingers is bordered on each
side by one finger of said second set of fingers.
7. The valve stem seal assembly, as in claim 1, wherein said first
and second sets of fingers are circumferentially and symmetrically
arranged about said axis of said retainer.
8. The valve stem seal assembly, as in claim 1, wherein said upper
ends of said first and second sets of fingers are axially offset
from each other.
9. A valve stem seal assembly adapted for installation atop of a
valve guide of an internal combustion engine for sealingly engaging
a valve stem reciprocally moveable through the valve guide, the
seal assembly comprising: a retainer defining a generally rigid
cylindrical body having an axis and including an upper body end and
a lower body end; a resilient annular seal body defining an
interior annular sealing lip adapted to engage the valve stem and
further including a first exterior annular groove and a second
exterior annular groove wherein said first exterior annular groove
and said second exterior annular groove are axially offset; a first
set of fingers disposed from said lower body end of said retainer
and comprising radially inwardly depending upper ends for engaging
said first exterior annular groove of said seal body to maintain
said seal body axially against a top surface of the valve guide;
and a second set of fingers disposed from said lower body end of
said retainer and comprising radially inwardly depending upper ends
for engaging said second exterior annular groove of said seal body
to impart a circumferential force to said sealing lip and to urge
said sealing lip against the reciprocally moveable valve stem.
10. The valve stem seal assembly, as in claim 9, wherein said
second set of fingers has a different length than said first set of
fingers.
11. The valve stem seal assembly, as in claim 9, wherein said first
set of fingers are generally parallel to said axis of said retainer
and said upper ends of said first set of fingers are generally
perpendicular to said axis for engaging said first exterior annular
groove of said seal body.
12. The valve stem seal assembly, as in claim 9, wherein said
second set of fingers are generally arcuate over the length of the
fingers for adjusting said circumferential force applied to the
sealing lip.
13. The valve stem seal assembly, as in claim 9, wherein said seal
body further comprises a lower circumferential flange defining a
bottom surface adapted to sealing engage the top surface of the
valve guide.
14. The valve stem seal assembly, as in claim 9, wherein said first
and second sets of fingers are circumferentially and symmetrically
arranged about said axis of said retainer.
15. The valve stem seal assembly, as in claim 9, wherein said first
and second sets of fingers are circumferentially alternating, such
that each finger of said first set of fingers is bordered on each
side by one finger of said second set of fingers.
16. The valve stem seal assembly, as in claim 9, wherein said upper
ends of said first and second sets of fingers are axially offset
from each other.
17. The valve stem seal assembly, as in claim 9, wherein said first
set of fingers and said second set of fingers are radially offset
from each other about said axis of said retainer.
18. A valve stem seal assembly adapted for installation atop of a
valve guide of an internal combustion engine for sealingly engaging
a valve stem reciprocally moveable through the valve guide, the
seal assembly comprising: a retainer defining a generally rigid
cylindrical body having an axis and including an upper body end and
a lower body end; a resilient annular seal body defining an
interior annular sealing lip adapted to engage the valve stem and
further including a first exterior annular groove and a second
exterior annular groove wherein said first exterior annular groove
and said second exterior annular groove are axially offset; a first
set of fingers disposed from said lower body end of said retainer
and comprising radially inwardly depending upper ends for engaging
said first exterior annular groove of said seal body to maintain
said seal body axially against a top surface of the valve guide;
and a second set of fingers disposed from said lower body end of
said retainer and radially offset from said first set of fingers
about said axis of said retainer and further comprising radially
inwardly depending upper ends for engaging said second exterior
annular groove of said seal body to impart a circumferential force
to said sealing lip and to urge said sealing lip against the
reciprocally moveable valve stem.
Description
RELATED APPLICATIONS
[0001] The present invention is related to U.S. patent application
Ser. No. 09/792,971 filed on Feb. 26, 2001, the entire contents of
which are herein incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a valve stem seal
assemblies for use in internal combustion engines and in particular
to sealing media retainers for such seal assemblies.
BACKGROUND OF THE INVENTION
[0003] Those skilled in the art will appreciate the manner in which
intake and exhaust valves are employed in cylinder heads of
internal combustion engines. Such valves, supported for reciprocal
motion within valve guides, include integral elongated valve stems
extending away from the engine cylinder heads. The ends of the
valve stems interact with rotating cams for cyclic repeated opening
and closing of the valves against the force of valve return springs
during a combustion cycle. Obviously, in order to permit
unobstructed reciprocal movement of the valve stem in the valve
guide, some mechanical clearance must exist between the valve guide
and the moving valve stem. The valve stems thus move reciprocally
to and from the cylinder head, each within its individual valve
guide, and so-called valve stem seal assemblies are used to seal
against leakage of oil through a clearance path between each
annular engine valve guide and its associated valve stem.
[0004] Thus, as is well known, the intake port of a combustion
chamber is opened and closed by the reciprocating motion of at
least one intake valve, which in turn is driven by the rotary
motion of a cam, the latter being affixed to and rotatable with an
engine camshaft. The intake valve permits fuel mixed with air to
flow into the combustion chamber. In addition, an internal
combustion engine has at least one exhaust valve and associated
exhaust port for releasing expended combustion gases to the
atmosphere. Typically, intake and exhaust valves are of similar
construction and both include valve stems integrally affixed to the
valves.
[0005] In the typical engine, a valve stem seal assembly is fitted
over or atop each valve guide, wherein each assembly has a retainer
frictionally mounted to an associated valve guide, or is retained
in place via cooperation of a return spring and a retainer flange,
to assure attachment of the valve stem seal assembly within the
engine. Typically each valve stem seal assembly has two primary
parts; 1) an elastomeric oil seal positioned at one end to control
leakage of oil between the valve stem and the valve guide, and 2) a
structural cylindrical part called a retainer mounted atop of the
valve guide. In many cases, the retainer has a so-called bottom
flange that extends circumferentially about the bottom of the valve
guide for supporting the retainer on the cylinder head deck.
Additionally, traditionally manufactured elastomeric oil seals
include an exterior groove for receiving a "garter spring" as
described below.
[0006] Much progress has been achieved in the art of valve stem
seal assembly design and construction. However, several design
issues remain problematic for traditional valve stem seal
assemblies. For example, the number of parts associated with a
valve stem seal assembly has typically been the seal body and the
retainer. However, a third part, called a "garter spring" is often
disposed within a circumferential groove about the exterior of the
seal body to impart a hoop stress or force to engage the seal body
with the valve stem and prevent leakage of oil. The garter spring
is typically made of metal and adds additional cost to the seal
body assembly. An additional difficulty with traditional seal
assemblies is verification of proper installation. Use of the
garter spring with the retainer requires separate verification for
each part. This additional verification also adds to the cost of
the seal body assembly.
SUMMARY OF THE INVENTION
[0007] The inventors of the present invention have recognized these
and other problems associated with traditional valve stem seal
assemblies. To this end, the inventors have developed an improved
valve stem seal assembly that eliminates the need for an additional
garter spring while still securing a seal body to a top of a valve
guide and engaging a valve stem.
[0008] Specifically, the invention is a valve stem seal assembly
adapted for installation atop a valve guide of an internal
combustion engine for sealingly engaging a valve stem reciprocally
moveable through the valve guide. The valve stem seal assembly
comprises a resilient annular seal body defining an interior
annular sealing lip adapted to engage the valve stem and further
including first and second exterior annular grooves. The assembly
also comprises a retainer defining a generally rigid cylindrical
body with upper and lower body ends and further defining an axis.
Furthermore, the assembly includes a first set of fingers disposed
from the lower body end to the upper body end of the retainer. The
first set of fingers comprises radially inwardly depending upper
ends at the upper body end of the retainer for engaging the first
exterior annular groove of the seal body to maintain the seal body
axially against the top surface of the valve guide. Additionally, a
second set of fingers is disposed between the lower body end and
the upper body end of the retainer. The second set of finger
comprises radially inwardly depending upper ends for engaging the
second exterior annular groove of the seal body to impart a
circumferential force urging the sealing lip against of the
reciprocally moveable valve stem.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0010] FIG. 1 is a perspective view of the valve stem seal assembly
of the present invention;
[0011] FIG. 2 is a cross-sectional view of a resilient elastomeric
seal body of the valve stem seal assembly of FIG. 1, depicting
particular construction details of the seal body;
[0012] FIG. 3 is a top view of the retainer of the present
invention revealing particular construction details of the two sets
of alternating fingers;
[0013] FIG. 4 is a cross-sectional view of a retainer along lines
4-4 of FIG. 3, depicting dual sets of fingers as employed in the
valve stem seal assembly of the present invention;
[0014] FIG. 5 is a cut-away view of the valve stem seal assembly as
depicted in FIG. 1, revealing cross-sectional views of the
connective relationship between the elastomeric seal body and the
metallic retainer; and
[0015] FIG. 6 is an identical cross-sectional view of the valve
stem seal assembly of FIG. 5, shown however in sealing engagement
with a valve stem in accordance with the contemplated usage of the
present invention in an internal combustion engine, and
particularly showing the valve stem seal assembly supported atop a
valve guide through which the valve stem is reciprocally
moveable.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] Referring initially to FIG. 1, a valve stem seal assembly 10
is constructed to includes a resilient elastomeric seal body 12
supported in a rigid cylindrical retainer 14 having an axis A-A. As
best seen in FIG. 6, an internal combustion engine (not shown)
includes a valve guide 16 with a central opening therethrough. The
opening receives a reciprocating valve stem 18. To prevent the
escape of oil, the valve stem seal assembly 10 is positioned over
the valve guide 16 and engages the valve stem 18.
[0017] The resilient seal body 12, as best shown in FIG. 2, is
generally annular in shape and includes interior and exterior
surfaces 20 and 22, respectively. Within its interior surface 20,
the seal body 12 incorporates a circumferentially extending sealing
lip 24 for contacting the reciprocally moving valve stem 18 and
preventing leakage of oil. As shown in the preferred embodiment,
the seal body 12 may have only one sealing lip 24, but one skilled
in the art is aware of the advantages of having multiple sealing
lips engaging the valve stem 18. Furthermore, the exterior surface
22 of the seal body 12 includes a first exterior annular groove 26
and a second exterior annular groove 28. The grooves 26, 28 of the
seal body 12 are axially offset from each other along the axis A-A
with the second groove 28 being positioned higher than the first
groove 26.
[0018] The seal body 12 is supported atop the valve guide 16 and
contacts the valve stem 18 by the retainer 14. The retainer 14 is
generally rigid and is typically made from a metallic or plastic
material depending upon the rigidity and heat characteristics
needed as a result of engine demand. The retainer 14 includes a
first set of fingers 30 and a second set of fingers 32 extending
from a lower body end 34 to an upper body end 36 of the retainer
14. The first and second sets of finger 30, 32 each include upper
ends 38, 40 respectively. The upper ends 38, 40 are positioned at
the upper body end 36 of the retainer 14 and extend radially
inwardly to engage the grooves 26, 28 of the seal body 12. As best
seen in FIG. 5, the upper ends 38 of the first set of fingers 30
engage the first exterior annular groove 26, while the upper ends
40 of the second set of fingers 32 engage the second exterior
annular groove 28. Accordingly, because the grooves 26, 28 are
axially offset, the first and second sets of fingers 30, 32 are of
different lengths with the second set of fingers 32 preferably
generally longer than the first set of fingers 30.
[0019] The upper ends 38 of the first set of fingers 30 engage the
first groove 26 to maintain the seal body 12 axially against a top
surface 42 of the valve guide 16. The seal body 12 includes a lower
circumferential flange 44 having a bottom surface 46. The bottom
surface 46 of the seal body 12 contacts the top surface 42 of the
valve guide 16. The first set of fingers 30 in the first groove 26
exerts an inward and downward force upon the seal body 12 to
maintain contact between the bottom surface 46 of the seal body 12
and the top surface 42 of the valve guide 16. In accordance with
the present invention, the first set of fingers 30 is generally
parallel to the axis A-A of the retainer 14. The upper ends 38 of
the first set of fingers 30 are turned radially inward and are
generally perpendicular to the axis A-A of the retainer 14.
Although shown in FIG. 4 and described as a z-shape configuration,
the z-shape configuration of the first set of fingers 30 is only a
preferred embodiment and one skilled in the art may contemplate an
alternative shape to achieve the result of maintaining the seal
body 12 axially against the top surface 42 of the valve guide
16.
[0020] The upper ends 40 of the second set of fingers 32 engage the
second groove 28 to impart a circumferential force to the sealing
lip 24 of the seal body 12. The circumferential force urges the
sealing lip 24 against the reciprocally moveable valve stem 18,
thereby providing a seal between the sealing lip 24 of the seal
body 12 and the reciprocally moveable valve stem 18 to prevent the
leakage of oil. The circumferential force generated by the second
set of fingers 32 eliminates the need for a "garter spring" thereby
reducing the quantity of parts and improving assembly verification
techniques. In accordance with the present invention, the second
set of fingers 32 is generally arcuate over the length of the
fingers 32. The arcuate bend helps to engage the upper ends 38 of
the second set of fingers 32 in the second groove 28 thereby
axially offsetting the upper ends 38, 40 of the sets of fingers 30,
32. As described above, because the grooves 26, 28 are axially
offset, the second set of fingers 32 is a different length than the
first set of fingers 30. As a result of the difference in length
between the first and second set of fingers 30, 32, the bending
strain is more evenly distributed over a larger area of the seal
body 12. Accordingly, a more stable circumferential force is
applied to the sealing lip 24 of the seal body 12 under varying
engine heat cycles. Furthermore, to adjust the amount of
circumferential force applied to the sealing lip 24 of the seal
body 12, the arcuate bend can be adjusted during design and
manufacture of the valve stem seal assembly 10. Therefore, the
arcuate bend of the second set of fingers 32 provides a more
flexible design that is more suitably adapted for different
vehicles and engines. Again, as described and shown in the figures,
the second set of fingers is generally arcuate, however, the
arcuate shape is only a preferred embodiment and one skilled in the
art may contemplate an alternative design that achieves the
resulting circumferential force applied to the sealing lip 24 of
the seal body 12.
[0021] It will also be appreciated by those skilled in the art that
manufacture of the retainer 14 can be achieved in a variety of
ways. Referring to FIG. 3, it is apparent that the first set of
fingers 30 and second set of fingers 32 are circumferentially and
symmetrically arranged about the axis A-A of the retainer 14. In
the embodiments herein described it is, however, preferable that
the fingers of each set 30, 32 have circumferential spacing or gaps
48 between them. The gaps 48 are for the purpose of avoiding
frictional interference between movements of adjacent fingers of
sets 30, 32 during the working or useful life of the valve stem
seal assembly 10. The gaps 48 can be of a relatively small order of
magnitude, as will be appreciated by those skilled in the art. In
addition, this invention will accommodate other circumferential
arrangements of the fingers of each set 30, 32. Thus, for example,
the fingers of each set 30, 32 could be arranged so that there are
two fingers of the first set 30 positioned side-by-side followed by
two fingers of the second set 32 side-by-side. Such modified
arrangement as well as others are deemed herein to be feasible,
notwithstanding the described preferred embodiment which provides
the circumferentially alternating arrangement wherein each finger
of the first set 30 is bordered on each side by a finger of the
second set 32, as depicted in the Figures. Furthermore, in a
preferred arrangement, the first and second sets of fingers 30, 31
are radially offset from each other about the axis of the retainer
14.
[0022] It should be understood that the aforementioned and other
various alternatives to the embodiments of the invention described
herein may be employed in practicing the invention. It is intended
that the following claims define the scope of the invention and
that the method and apparatus within the scope of these claims and
their equivalents be covered thereby.
* * * * *