Cam end cover and gasket assembly

Information

  • Patent Grant
  • 6701884
  • Patent Number
    6,701,884
  • Date Filed
    Friday, May 3, 2002
    22 years ago
  • Date Issued
    Tuesday, March 9, 2004
    20 years ago
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)
Number Name Date Kind
3625527 Brindle Dec 1971 A
4227705 Kuramoto Oct 1980 A
4396200 Ukai et al. Aug 1983 A
4951623 Jingu et al. Aug 1990 A
4970999 Jingu et al. Nov 1990 A
5199721 Schmitt Apr 1993 A
Foreign Referenced Citations (2)
Number Date Country
63094059 Apr 1988 JP
08218817 Aug 1996 JP