Information
-
Patent Grant
-
6701884
-
Patent Number
6,701,884
-
Date Filed
Friday, May 3, 200222 years ago
-
Date Issued
Tuesday, March 9, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Argenbright; Tony M.
- Ali; Hyder
Agents
- Michael Best & Friedrich LLP
-
CPC
-
US Classifications
Field of Search
US
- 123 195 C
- 123 1935
- 123 9027
- 123 9038
- 123 9031
- 123 9037
- 123 198 E
- 277 592
- 277 593
- 277 594
- 277 595
-
International Classifications
-
Abstract
An overhead cam motorcycle engine includes a cylinder head, a cam cover coupled to the cylinder head, a sealing gasket, and a substantially rigid insert. The cylinder head includes an aperture that is substantially axially aligned with an engine camshaft axis. The resilient gasket includes a sealing jacket that defines an opening. The gasket is positioned between the cylinder head and the cam cover such that the sealing jacket occupies the aperture. The insert is positioned in the opening in the sealing jacket to seal the cylinder head and cam cover interface.
Description
FIELD OF THE INVENTION
The invention relates to motorcycles, and more particularly to motorcycles having overhead cam engines.
BACKGROUND OF THE INVENTION
The use of overhead cam engines, and more particularly dual overhead cam engines, is well known in the motorcycle industry. Tolerance limits on the casting process used to form the cylinder head of an overhead cam engine make it necessary to ream the cam shaft bearing seats, which are integrally cast into the cylinder head. The reaming ensures the proper alignment and rotation of the camshafts inside the cam case. In order to ream the bearing seats in the relatively confined cylinder head casting, it is necessary to first cast or machine a semi-circular recess in the side wall of the cylinder head and in alignment with the bearing seats. The reaming bit then has an unobstructed path to perform its operation. Aside from facilitating the reaming operation, the semi-circular recess in the cylinder head serves no purpose and must be closed off when the cam cover is placed on the cylinder head.
Prior art dual overhead cam engines typically include a resilient sealing gasket at the split line between the cylinder head and the cam cover. The sealing gasket includes integral semi-circular or “half-moon” cam end cover portions that fit in the semi-circular recesses so that the cylinder head and the sealing gasket together form a substantially flat and continuous upper peripheral edge. The cam cover, which has a flat lower peripheral edge corresponding in shape to the upper peripheral edge of the sealing gasket, is then mounted on the cylinder head to enclose the cam shafts and define the upper portion of the cam case. The sealing gasket substantially seals the joint between the cylinder head and the cam cover.
SUMMARY OF THE INVENTION
Prior art cam case sealing gaskets suffer from various problems. The half-moon cam cover portions are typically molded from the same resilient, elastomeric material as the remainder of the sealing gasket. Because of their resilience, the cam end cover portions often provide a less than adequate seal between the cylinder head and the cam cover. Typically, silicone or other sealing materials must be used on the cam end cover portions, the cam cover, or both prior to mounting the cam cover on the cylinder head to ensure that the semi-circular recesses remain properly sealed. The sealing material may also need to be re-applied each time the cam cover is removed and then re-assembled. The elastomeric half-moon cam cover portions also tend to lack aesthetic appeal.
The present invention provides a motorcycle including a frame, an engine crankcase and cylinder assembly coupled to the frame, a cylinder head coupled to the crankcase and cylinder assembly, a cam cover coupled to the cylinder head, and a substantially rigid insert. The cylinder head includes a camshaft support surface and a cylinder head wall. The camshaft support surface defines a camshaft axis and the cylinder head wall partially defines an aperture that is substantially axially aligned with the camshaft axis. The cam cover cooperates with the cylinder head wall to further define the aperture, and the insert is positioned in the aperture.
The aperture includes a first boundary that is defined by the cylinder head, and a second boundary that is defined by the cam cover, and the insert includes a first profile corresponding to the first boundary, and a second profile corresponding to the second boundary. In some embodiments, the first and second profiles cooperate to define a semi-circular inner portion of the insert. In other embodiments, the first and second profiles cooperate to define a circular inner portion of the insert.
The motorcycle may also include a sealing jacket that surrounds the insert and engages the cylinder head and the cam cover. The sealing jacket may be integrally formed with a resilient sealing member that is positioned between the cylinder head and the cam cover. The insert may also include a substantially circular outer portion that overlies portions of the cylinder head wall and the cam cover.
The present invention also provides a method for sealing an interface between a cylinder head and a cam cover. The cylinder head includes a camshaft support surface that defines a camshaft axis, and a cylinder head wall that defines an aperture. The aperture is adjacent the interface and is substantially aligned with the camshaft axis. A substantially rigid insert is provided and a resilient sealing member including a resilient sealing jacket is positioned around the insert. The resilient sealing member is located between the cylinder head and the cam cover such that the resilient sealing jacket and the insert occupy the aperture.
The present invention also provides a method of making a sealing gasket and insert assembly for an overhead cam motorcycle engine. The method includes providing a rigid insert and a continuous sealing gasket that includes a sealing jacket defining an opening. The sealing gasket is positioned around the insert such that the insert is positioned in the opening and the sealing jacket substantially surrounds and retains the insert. The gasket may be molded around the insert or alternatively the insert may be pressed into the opening.
The present invention also provides a method for replacing a substantially rigid old insert having an inner portion received by an opening in a sealing gasket. The sealing gasket is positioned in an interface between a cylinder head and a cam cover of an overhead cam motorcycle engine, and the old insert has an outer portion overlying portions of the cylinder head and the cam cover. The method includes providing a substantially rigid replacement insert including an inner portion that is positionable within the opening. The old insert is removed from the opening; and the replacement insert is inserted into the opening. A replacement sealing gasket including an opening may also be provided and the replacement sealing gasket may be positioned in the interface in place of the original gasket.
The present invention also provides a method for replacing a sealing gasket positioned in an interface between a cylinder head and a cam cover of an overhead cam motorcycle engine. The sealing gasket includes an opening that receives an inner portion of a substantially rigid insert, and the insert has an outer portion overlying portions of the cylinder head and the cam cover. The method includes decoupling the cam cover from the cylinder head and removing the sealing gasket from the interface. The insert is removed from the sealing gasket opening and a replacement sealing gasket including an opening configured to receive the inner portion of the insert is provided. The inner portion of the insert is inserted into the opening of the replacement gasket, the replacement gasket is positioned in the interface, and the cam cover is recoupled to the cylinder head.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a side elevation view of a motorcycle embodying the present invention.
FIG. 2
is a side view of an internal combustion engine with a portion cut away.
FIG. 3
is an exploded view of a cylinder head and cam cover of the internal combustion engine.
FIG. 4
is section view of the cylinder head and cam cover taken along line IV—IV of FIG.
2
.
FIG. 5
is a perspective view of a cam end cover of the internal combustion engine.
FIG. 6
is a partial perspective view of a cam end seal of the internal combustion engine.
FIG. 7
is a top view of a cam cover seal and cam end cover of the internal combustion engine.
FIG. 8
is a section view taken along line VIII—VIII of FIG.
7
.
Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1
illustrates a motorcycle
10
including a frame
12
, an overhead cam internal combustion engine assembly
14
mounted to the frame
12
, front and rear wheels
16
,
18
supporting the frame
12
, a steering assembly
20
including handlebars
22
and a fork
24
mounted to the front wheel
16
and pivotal with respect to the frame
12
, and a swing arm
26
(partially hidden) interconnecting the rear wheel
18
to the frame
12
.
Referring to
FIGS. 2 and 3
, the illustrated engine assembly
14
is configured as a V-twin engine and includes an upper crankcase portion
28
having integrally-formed engine cylinders
30
,
32
that receive engine pistons (not shown). Cylinder heads
34
,
36
are secured to the engine cylinders
30
,
32
respectively and house various valve drive components for the internal-combustion engine
14
. In the illustrated embodiment, intake and exhaust camshafts as well as spring-loaded intake and exhaust valves (not shown) are positioned in each cylinder head
34
,
36
(only the cylinder head
34
being shown in FIG.
3
). The intake and exhaust camshafts engage cam followers to actuate the valves in a known manner.
The cylinder heads
34
,
36
cooperate with respective cam covers
38
,
40
to define a cam case or chamber, the cylinder heads
34
,
36
forming the lower portion of the cam case, and the cam covers
38
,
40
forming the upper portion of the cam case. The illustrated cam covers
38
,
40
are constructed of two parts and include base covers
38
a
,
40
a
, and cam gear covers
38
b
,
40
b
. The base covers
38
a
,
40
a
include a lower peripheral edge
42
that is configured to mate with an upper peripheral edge
44
of a respective cylinder head
34
,
36
to define a cam case interface. The cam covers
38
,
40
are fastened to the cylinder heads
34
,
36
with suitable bolts
46
. In addition, an opening
48
configured to receive a spark plug
50
is also formed in each base cover
38
a
,
40
a
. The cam gear covers
38
b
,
40
b
are secured to the base covers
38
a
,
40
a
by the bolts
46
, which also secure the entire cam covers
38
,
40
to the cylinder heads
34
,
36
, as well as by additional bolts
51
, which generally extend only into the base covers
38
a
,
40
a
. The cam gear covers
38
b
,
40
b
include arcuate chamber portions
52
that receive driving gears for the camshafts. A resilient seal
53
is positioned between the base covers
38
a
,
40
a
and the cam gear covers
38
b
,
40
b
. Some embodiments of the invention include cam covers
38
,
40
that are integrally formed as one piece and include the structural features of both the base covers
38
a
,
40
a
and the cam gear covers
38
b
,
40
b.
With respect to the features described further below, the construction and arrangement of the cylinder heads
34
,
36
and the cam covers
38
,
40
are substantially the same. As such, the following description will be presented only with respect to one cylinder head
34
and one cam cover
38
. A resilient sealing gasket
54
is positioned between the upper peripheral edge
44
of the cylinder head
34
and the lower peripheral edge
42
of the cam cover
38
to seal the interface. Formed in the cylinder head
34
are two sets of camshaft support surfaces
56
,
58
that are configured to rotatably support the camshafts. The support surfaces
56
,
58
are generally semi-circular and define camshaft axes
60
,
62
. The camshaft support surfaces
56
,
58
must be precisely formed and are therefore machined into the cylinder head
34
using suitable boring or milling tools. In order to machine the bearing support surfaces
56
,
58
, apertures
64
are provided in a cylinder head wall
66
. The apertures
64
are each aligned with a respective camshaft axis
60
,
62
such that the machine tools may be extended through the apertures
64
to machine the camshaft support surfaces
56
,
58
. As illustrated, the apertures
64
are substantially semi-circular and generally define recesses in, and have arcuate boundaries defined by, the upper peripheral edge
44
of the cylinder head
34
. In addition, the lower peripheral edge
42
of the cam cover
38
defines additional substantially linear boundaries of the apertures
64
when the cam cover
38
is coupled to the cylinder head
34
.
Referring to
FIGS. 4-6
, effective sealing of the cam case is achieved by providing substantially rigid inserts
68
(
FIG. 5
) positioned within the apertures
64
. The inserts
68
are preferably made of a metal such as aluminum, which has a modulus of elasticity of about 69 GPa (10×10
6
psi), however other metals having different moduli of elasticity are possible. In addition to metals, other substantially rigid fabrication materials (e.g. plastics) having flexural moduli of at least about 1 GPa (150 ksi) are possible as well. In a first embodiment, the inserts
68
include a substantially semi-circular inner portion
70
that is received by the apertures
64
. The inner portion
70
has a first arcuate profile that corresponds to the arcuate aperture boundary provided by the cylinder head
34
, and a second substantially linear profile that corresponds to the linear aperture boundary provided by the cam cover
36
. The inserts
68
also include a substantially circular outer portion
72
that overlies portions of the cylinder head wall
66
and the cam cover
38
.
To provide effective sealing around the inserts
68
, the sealing gasket
54
includes sealing jackets
74
(
FIG. 6
) that are adapted to receive and surround the inner portion
70
of the inserts
68
. The sealing jacket
74
includes a semi-circular opening
76
that receives the inner portion
70
and a resilient sealing strip
78
that is substantially continuous with the remainder of the sealing gasket
54
. A resilient sealing lug
80
extends around the sealing jacket
74
and is substantially continuous with the sealing strip
78
. In some embodiments, the lower peripheral edge
42
of the cam cover
38
includes a groove
82
that is adapted to receive the sealing strip
78
. The sealing jacket
74
also includes a resilient sealing flange or flap
84
that is positioned between the cam cover
38
and the outer portion
72
of the inserts
68
to further seal the interface and reduce and/or damp vibrations of the outer portion
72
during motorcycle operation.
To seal the apertures
64
, the inner portions
70
of each insert
68
are pressed into the openings
76
of the sealing jackets
74
and positioned, along with the sealing gasket
54
, between the base cover
38
a
and the cylinder head
34
such that the sealing jackets
74
and the inserts
68
occupy the apertures
64
as illustrated in FIG.
4
. Once the sealing gasket
54
and the inserts
68
are properly positioned on the cylinder head
34
, the cam cover
38
is secured to the cylinder head
34
using the bolts
46
. Thus, the inserts
68
occupy a majority of the apertures
64
, and the sealing lugs
80
seal the apertures
64
along the cylinder head
34
and the sealing strips
78
, and the sealing flaps
84
seal the apertures
64
along the cam cover
38
. For aesthetic purposes, the circular outer portion
72
of the insert
68
includes a raised circumferential collar
86
. However, as discussed below, the outer portion
72
may include other aesthetic features as well.
FIGS. 7 and 8
illustrate a second embodiment of the invention wherein the inserts
68
′ are substantially uniformly circular. The second embodiment is particularly well suited for a motorcycle having the cam cover
38
fabricated as a unitary piece as mentioned above. In this event, the cam cover
38
is provided with semi-circular apertures that are substantially mirror images of the apertures
64
in the cylinder head
34
and define recesses in the lower peripheral edge
42
of the cam cover
38
. The apertures in the cam cover
38
substantially oppose the semi-circular apertures
64
in the cylinder head
34
when the cam cover
38
is mounted to the cylinder head
34
. The opposed apertures in the cam cover
38
and the cylinder head
34
thus cooperate to define a single, substantially circular aperture communicating with the cam case.
As illustrated in
FIGS. 7 and 8
, the sealing gasket
54
′ may be molded directly around the inserts
68
′, thereby forming the sealing jacket
74
′. It should be appreciated that the previously-described sealing gasket
54
may also be molded directly around the inserts
68
. To seal the cam case, the sealing gasket
54
′ and the inserts
68
′ are positioned on the upper peripheral edge
44
of the cylinder head
34
, and the one piece cam cover
38
is secured to the cylinder head
34
such that circular inner portions
70
′ of the inserts
68
′ occupy the circular apertures, much the same way as the semi-circular inner portions
70
occupy the semi-circular apertures
64
. Similar to the first embodiment, the sealing jacket
74
′ includes a sealing strip
78
′ that seals the aperture along the cam cover
38
, and the insert
68
′ includes a circular outer portion
72
′ including a raised circumferential collar
86
′ for aesthetic appeal.
With the construction and arrangement of the embodiments described above, the sealing gasket
54
and the inserts
68
provide for the replacement of the inserts
68
and the gasket
54
either alone or in combination. For example, if an insert
68
becomes damaged, or if it is desired to replace the insert
68
with a new insert
68
or an alternate insert having a different aesthetic appearance, the cam cover
38
is removed from the cylinder head
34
and the gasket
54
and the inserts
68
are removed from the interface. The inserts
68
may then be removed from the openings
76
in the sealing jackets
74
and the new/alternate inserts are then inserted into the openings
76
. The gasket
54
, including the new/alternate inserts, is then repositioned in the interface and the cam cover
38
is recoupled to the cylinder head
34
. Alternatively, if the gasket
54
is worn or damaged but the inserts
68
are otherwise intact, a new gasket, similar to the old gasket
54
may be provided. The new gasket, having the same inserts
68
inserted therein, may then be installed in place of the old gasket
54
. Also, inserts
68
having differently shaped or contoured outer portions
72
, or outer portions
72
that display various icons or indicia thereon may be provided and installed to customize or otherwise alter the aesthetic appearance of the motorcycle
10
. With respect to the examples given above, the gasket
54
and insert
68
assembly potentially reduces the cost of replacing a worn, damaged, or otherwise unwanted gasket
54
or insert
68
because the components may be replaced independently of each other.
While the forgoing description has been presented with respect to an overhead cam V-twin engine, it should be appreciated that the teachings of the present invention are applicable to substantially any engine type requiring the sealing of apertures that may be positioned along various engine interfaces.
Various features of the invention are set forth in the following claims.
Claims
- 1. A motorcycle comprising:a frame; an engine crankcase and cylinder assembly coupled to the frame; a cylinder head coupled to the crankcase and cylinder assembly and including a camshaft support surface and a cylinder head wall, the camshaft support surface defining a camshaft axis and the cylinder head wall partially defining an aperture that is substantially axially aligned with the camshaft axis; a cam cover coupled to the cylinder head and cooperating with the cylinder head wall to further define the aperture; and a substantially rigid insert positioned in the aperture; and a sealing jacket that surrounds the insert and engages the cylinder head and the cam cover.
- 2. The motorcycle of claim 1, wherein the aperture is substantially semi-circular and the insert includes a substantially semi-circular inner portion received by the aperture.
- 3. The motorcycle of claim 1, wherein the aperture is substantially circular and the insert includes a substantially circular inner portion received by the aperture.
- 4. The motorcycle of claim 1, wherein the sealing jacket is integrally formed with a resilient sealing member positioned between the cylinder head and the cam cover.
- 5. The motorcycle of claim 1, wherein the insert includes a substantially circular outer portion that overlies portions of the cylinder head wall and the cam cover.
- 6. The motorcycle of claim 5, wherein the sealing jacket includes a flap portion positioned between the cam cover and the circular outer portion.
- 7. The motorcycle of claim 1, wherein the insert includes a substantially circular outer portion that overlies the cylinder head wall and the cam cover.
- 8. The motorcycle of claim 1, wherein the aperture includes a first boundary defined by the cylinder head and a second boundary defined by the cam cover, and the insert includes a first profile corresponding to the first boundary, and a second profile corresponding to the second boundary.
- 9. The motorcycle of claim 8, wherein the first and second profiles cooperate to define a semi-circular inner portion of the insert.
- 10. The motorcycle of claim 8, wherein the first and second profiles cooperate to define a circular inner portion of the insert.
- 11. A method for sealing an interface between a cylinder head and a cam cover, the cylinder head including a camshaft support surface defining a camshaft axis and a cylinder head wall defining an aperture, the aperture being adjacent the interface and substantially aligned with the camshaft axis, the method comprising:providing a substantially rigid insert; positioning a resilient sealing member including a resilient sealing jacket around the insert; and locating the resilient sealing member between the cylinder head and the cam cover such that the resilient sealing jacket and the insert occupy the aperture.
- 12. The method of claim 11, wherein the jacket includes an opening and positioning the resilient sealing member around the insert includes inserting a portion of the insert into the opening.
- 13. The method of claim 11, wherein locating the sealing member between the cylinder head and the cam cover includes positioning a substantially circular outer portion of the insert in overlying relation to portions of at least one of the cylinder head and the cam cover.
- 14. The method of claim 11, wherein locating the resilient sealing member between the cylinder head and the cam cover includes positioning a flap portion of the sealing jacket between an outer circular portion of the insert and the cam cover.
- 15. A sealing gasket and insert assembly for sealing an interface between a cylinder head and a cam cover of an overhead cam motorcycle engine, the sealing gasket and insert assembly comprising:a resilient sealing gasket positionable within the interface and including a sealing jacket; and a substantially rigid insert surrounded by and coupled to the sealing jacket.
- 16. The sealing gasket and insert assembly of claim 15, wherein the insert includes an outer portion positionable in overlying relation to portions of at least one of the cylinder head and the cam cover.
- 17. The sealing gasket and insert assembly of claim 15, wherein the sealing jacket is molded around the insert.
- 18. The sealing gasket and insert assembly of claim 15, wherein the sealing jacket includes an opening and the insert is positioned in the opening.
- 19. The sealing gasket and insert assembly of claim 15, wherein the insert further includes a substantially semi-circular inner portion.
- 20. A method of making a sealing gasket and insert assembly for an overhead cam motorcycle engine, the method comprising:providing a rigid insert; providing a sealing gasket including a sealing jacket, the sealing jacket defining an opening; and positioning the sealing gasket around the insert such that the sealing jacket substantially surrounds and retains the insert.
- 21. The method of claim 20, wherein positioning the sealing gasket around the insert includes molding the gasket around the insert.
- 22. The method of claim 20, wherein positioning the sealing gasket around the insert includes pressing the insert into the opening.
- 23. The method of claim 20, wherein the sealing jacket includes a flap portion, and wherein positioning the insert within the opening includes positioning an outer circular portion of the insert adjacent to the flap portion.
- 24. A method for replacing a substantially rigid old insert having an inner portion received by an opening in a sealing gasket, the sealing gasket positioned in an interface between a cylinder head and a cam cover of an overhead cam motorcycle engine, the method comprising:providing a substantially rigid replacement insert including an inner portion positionable within the opening; removing the old insert from the opening; and inserting the replacement insert into the opening.
- 25. The method of claim 24, wherein the old insert has an outer portion overlying portions of at least one of the cylinder head and the cam cover, and wherein inserting the replacement insert into the opening includes positioning an outer portion of the replacement insert in overlying relation to portions of at least one of the cylinder head and cam cover.
- 26. The method of claim 24, wherein removing the old insert includes decoupling the cam cover from the cylinder head and removing the sealing gasket from the interface.
- 27. The method of claim 24, further comprising providing a replacement sealing gasket including an opening and positioning the replacement sealing gasket in the interface.
- 28. The method of claim 24, further comprising aligning the replacement insert with a camshaft axis of the cylinder head.
- 29. A method for replacing a sealing gasket positioned in an interface between a cylinder head and a cam cover of an overhead cam motorcycle engine, the sealing gasket including an opening that receives an inner portion of a substantially rigid insert, the insert having an outer portion overlying portions of at least one of the cylinder head and the cam cover, the method comprising:decoupling the cam cover from the cylinder head; removing the sealing gasket from the interface; removing the insert from the sealing gasket opening; providing a replacement sealing gasket including an opening configured to receive the inner portion of the insert; inserting the inner portion into the opening of the replacement gasket; positioning the replacement gasket in the interface; and recoupling the cam cover to the cylinder head.
- 30. The method of claim 29, wherein inserting the inner portion into the opening of the replacement gasket includes positioning an outer portion of the insert in overlying relation to portions of the cylinder head and cam cover.
- 31. The method of claim 29, further comprising providing a replacement insert including an inner portion receivable by the opening of the replacement gasket.
- 32. The method of claim 29, further comprising aligning the insert with a camshaft axis of the cylinder head.
Priority Claims (1)
Number |
Date |
Country |
Kind |
101 21 947 |
May 2001 |
DE |
|
US Referenced Citations (6)
Foreign Referenced Citations (2)
Number |
Date |
Country |
63094059 |
Apr 1988 |
JP |
08218817 |
Aug 1996 |
JP |