Internal combustion engine

Information

  • Patent Grant
  • 6708658
  • Patent Number
    6,708,658
  • Date Filed
    Wednesday, November 21, 2001
    23 years ago
  • Date Issued
    Tuesday, March 23, 2004
    20 years ago
Abstract
In an internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head, and rocker arms moved with the rotation of the camshaft and swingably carried on rocker shafts, a rocker shaft holder fastened and fixed to the bearing sections to support the rocker shafts is provided with accommodating recesses into each of which a portion of each of the bearing sections protrudes. Thus, the support rigidity of the rocker shafts can be enhanced and moreover, an increase in size of the engine can be avoided.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to an improvement of an internal combustion engine in which bearing sections rotatably carrying a camshaft are provided on a cylinder head, and rocker arms moved with the rotation of the camshaft and swingably carried on rocker shafts.




2. Description of the Related Art




Such internal combustion engines are conventionally known, for example, from Japanese Patent Application Laid-open Nos.6-17613 and 10-148113.




In the prior arts disclosed in the above Patent Applications, the rocker shafts are fixed to the bearing sections by bolts passed through the rocker shafts on one diametrical line and fastened to the bearing sections. Therefore, when the fastening of the bolts is only conducted, there is a possibility that the support rigidity of the rocker shafts is sufficient.




There is also an internal combustion engine already known, for example, from Japanese Patent No.2688732 and the like, in which rocker shafts are supported on a rocker shaft holder which includes a plurality of shaft-supporting sections fastened respectively to a plurality of bearing sections of a cylinder head for rotatably carrying a camshaft, and a connecting section connecting the shaft-supporting sections to one another. In this internal combustion engine, it is doubtful that the support rigidity of the rocker shafts is sufficient, because the rocker shafts are supported only by rocker shaft holder.




SUMMARY OF THE INVENTION




Accordingly, it is an object of the present invention to provide an internal combustion engine, wherein the support rigidity of the rocker shafts is enhanced sufficiently.




To achieve the above object, according to a first aspect and feature of the present invention, there is provided an internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head, and rocker arms moved with the rotation of the camshaft and swingably carried on rocker shafts, wherein a rocker shaft holder fastened and fixed to the bearing sections to support the rocker shafts is provided with accommodating recesses into each of which a portion of each of the bearing sections protrudes.




With such arrangement of the first feature, the rocker shaft holder is fastened and fixed to the bearing sections provided on the cylinder head to rotatably carry the camshaft, and the rocker shafts are supported on the rocker shaft holder, and hence, support rigidity of the rocker shafts can be enhanced. Moreover, the accommodating recesses are provided in the rocker shaft holder, and a portion of each of the bearing section protrudes into each of the recesses. Therefore, the fastening structure for the bearing sections and the rocker shaft holder can be formed compactly in a direction of axes of the cylinders, thereby avoiding an increase in size of the engine.




According to a second aspect and feature of the present invention, in addition to the first feature, a portion of each of the bearing sections protrudes into each of the accommodating recesses to avoid the contact with the rocker shaft holder. With such arrangement, it is possible to inhibit the vibration of the camshaft to utmost from being transmitted to the rocker shafts through the rocker shaft holder.




According to a third aspect and feature of the present invention, in addition to the second feature, the plurality of rocker shafts parallel to one another are supported on the rocker shaft holder, and the accommodating recesses are provided in the rocker shaft holder between the rocker shafts. With such arrangement, the fastening structure for the bearing sections and the rocker shaft holder can be formed further compactly in a direction of axes of the cylinders in such a manner that the distance between each of the rocker shafts and the camshaft can be shortened.




According to a fourth aspect and feature of the present invention, in addition to the third feature, the rocker shaft holder includes a plurality of shaft-supporting sections fastened to the plurality of bearing sections and provided with the accommodating recesses, respectively, and a connecting section which integrally connects at least portions of the shaft-supporting sections corresponding to the accommodating recesses to one another. According to a fifth aspect and feature of the present invention, in addition to the second feature, the rocker shaft holder includes a plurality of shaft-supporting sections fastened to the plurality of bearing sections and provided with the accommodating recesses, respectively, and a connecting section which integrally connects at least portions of the shaft-supporting sections corresponding to the accommodating recesses to one another.




With the arrangement of the fourth and fifth features, it is possible to avoid a reduction in rigidity of the rocker shaft holder, in spite of the provision of the accommodating recesses in the shaft-supporting sections.




According to a sixth aspect and feature of the present invention, in addition to the first feature, the plurality of rocker shafts parallel to the one another are supported on the rocker shaft holder, and the accommodating recesses are provided in the rocker shaft holder between the rocker shafts. With such arrangement, the fastening structure for the bearing sections and the rocker shaft holder can be formed further compactly in a direction of axes of the cylinders in such a manner that the distance between each of the rocker shafts and the camshaft can be shortened.




According to a seventh aspect and feature of the present invention, in addition to the sixth feature, the rocker shaft holder includes a plurality of shaft-supporting sections fastened to the plurality of bearing sections and provided with the accommodating recesses, respectively, and a connecting section which integrally connects at least portions of the shaft-supporting sections corresponding to the accommodating recesses to one another. According to an eighth aspect and feature of the present invention, in addition to the first feature, the rocker shaft holder includes a plurality of shaft-supporting sections fastened to the plurality of bearing sections and provided with the accommodating recesses, respectively, and a connecting section which integrally connects at least portions of the shaft-supporting sections corresponding to the accommodating recesses to one another.




With the arrangement of the seventh and eighth features, it is possible to avoid a reduction in rigidity of the rocker shaft holder, in spite of the provision of the accommodating recesses in the shaft-supporting sections.




To achieve the above object, according to a ninth aspect and feature of the present invention, there is provided an internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head; and a rocker shaft holder which includes a plurality of shaft-supporting sections fastened to the plurality of bearing sections, respectively, and a connecting section integrally connecting the shaft-supporting sections to one another and which supports a rocker shaft swingably carrying thereon rocker arms and moved with the rotation of the camshaft, wherein the rocker shaft is supported on the shaft-supporting sections and also on shaft-supporting intermediate portions which are integrally provided on the connecting section and each disposed between the adjacent shaft-supporting sections.




With such arrangement of the ninth feature, the shaft-supporting sections of the rocker shaft holder are fastened to the plurality of bearing sections provided integrally or separately on the cylinder head to rotatably carry the camshaft, respectively, and the rocker shaft is supported on the shaft-supporting sections and also on the shaft-supporting intermediate portions integrally provided on the connecting section of the rocker shaft holder and disposed between the plurality of shaft-supporting sections. Therefore, it is possible to sufficiently enhance the support rigidity of the rocker shaft.




According to a tenth aspect and feature of the present invention, in addition to the ninth feature, the rocker shaft supported on the shaft-supporting intermediate portions and another rocker shaft having an axis parallel to such rocker shaft are supported on the rocker shaft holder, and a roller in rolling contact with a cam provided on the camshaft is supported on each of rocker arms swingably carried on the other rocker shaft at locations corresponding to the shaft-supporting intermediate portions, so that they are opposed to the shaft-supporting intermediate portions, and each of the shaft-supporting intermediate portions is provided with a notch for avoiding the interference with the roller. With such arrangement, the rocker arms each having the roller can be disposed sufficiently in proximity to the rocker shaft in spite of the existence of the shaft-supporting intermediate portions, whereby a valve-operating device including the rocker arms and the rocker shafts can be constructed compactly.




According to an eleventh aspect and feature of the present invention, in addition to the tenth feature, rocker arms disposed adjacent the shaft-supporting intermediate portions are swingably carried on the rocker shaft supported on the shaft-supporting intermediate portions. With such arrangement, the axial movement of the rocker arms can be restricted by each of the shaft-supporting intermediate portions, and a part exclusively for restricting the axial movement of the rocker arms is not required and hence, the number of parts can be reduced.




According to a twelfth aspect and feature of the present invention, in addition to the eleventh feature, the rocker shaft holder is integrally provided with ribs which extend in a direction parallel to the axis of the rocker shaft and connects the shaft-supporting sections and the shaft-supporting intermediate portions to each other. With such arrangement, it is possible to enhance the rigidity of the rocker shaft holder, particularly, the rigidity of the shaft-supporting intermediate portions and in turn, to further enhance the support rigidity of the rocker shafts.




According to a thirteenth aspect and feature of the present invention, in addition to the eleventh feature, the rocker shaft holder has an oil sump defined in its upper surface, and lubricating oil passages provided therein for guiding a lubricating oil from the oil sump to slide portions between the shaft-supporting intermediate portions and the rocker arms adjoining the shaft-supporting intermediate portions. With such arrangement, the lubricating oil can be supplied to the slide portions between shaft-supporting intermediate portions and the rocker arms without need of a part other than the rocker shaft holder.




According to a fourteenth aspect and feature of the present invention, in addition to the tenth feature, the rocker shaft holder is integrally provided with ribs which extend in a direction parallel to the axis of the rocker shaft and connects the shaft-supporting sections and the shaft-supporting intermediate portions to each other. With such arrangement, it is possible to enhance the rigidity of the rocker shaft holder, particularly, the rigidity of the shaft-supporting intermediate portions and in turn, to further enhance the support rigidity of the rocker shafts.




According to a fifteenth aspect and feature of the present invention, in addition to the ninth feature, the rocker arms disposed adjacent the shaft-supporting intermediate portions are swingably carried on the rocker shaft supported on the shaft-supporting intermediate portions. With such arrangement, the axial movement of the rocker arms can be restricted by the shaft-supporting intermediate portions, and a part exclusively for restricting the axial movement of the rocker arm is not required and hence, the number of parts can be reduced.




According to a sixteenth aspect and feature of the present invention, in addition to the fifteenth feature, the rocker shaft holder is integrally provided with ribs which extend in a direction parallel to the axis of the rocker shaft and connects the shaft-supporting sections and the shaft-supporting intermediate portions to each other. With such arrangement, it is possible to enhance the rigidity of the rocker shaft holder, particularly, the rigidity of the shaft-supporting intermediate portions and in turn, to further enhance the support rigidity of the rocker shafts.




According to a seventeenth aspect and feature of the present invention, in addition to the fifteenth feature, the rocker shaft holder has an oil sump defined in its upper surface, and lubricating oil passages provided therein for guiding a lubricating oil from the oil sump to slide portions between the shaft-supporting intermediate portions and the rocker arms adjoining the shaft-supporting intermediate portions. With such arrangement, the lubricating oil can be supplied to the slide portions between shaft-supporting intermediate portions and the rocker arms without need of a part other than the rocker shaft holder.




According to an eighteenth aspect and feature of the present invention, in addition to the ninth feature, the rocker shaft holder is integrally provided with ribs which extend in a direction parallel to the axis of the rocker shaft and connects the shaft-supporting sections and the shaft-supporting intermediate portions to each other. With such arrangement, it is possible to enhance the rigidity of the rocker shaft holder, particularly, the rigidity of the shaft-supporting intermediate portions and in turn, to further enhance the support rigidity of the rocker shafts.




The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIGS. 1

to


12


show an embodiment of the present invention, wherein





FIG. 1

is a front view of a V-shaped multi-cylinder internal combustion engine to which the present invention is applied;





FIG. 2

is a plan view taken along a line


2





2


in

FIG. 1

with a head cover removed;





FIG. 3

is a plan view similar to

FIG. 2

, but showing the internal combustion engine with a rocker shaft holder and a camshaft being partially cut away;





FIG. 4

is a sectional view taken along a line


4





4


in

FIG. 2

;





FIG. 5

is a sectional view taken along a line


5





5


in

FIG. 2

;





FIG. 6

is a sectional view taken along a line


6





6


in

FIG. 2

;





FIG. 7

is an enlarged sectional view taken along a line


7





7


in

FIG. 6

;





FIG. 8

is an enlarged sectional view taken along a line


8





8


in

FIG. 4

;





FIG. 9

is a sectional view taken along a line


9





9


in

FIG. 8

;





FIG. 10

is an enlarged sectional view taken along a line


10





10


in

FIG. 2

;





FIG. 11

is a view of a passage-defining member, taken in a direction of an arrow


11


in

FIG. 10

; and





FIG. 12

is an enlarged sectional view taken along a line


12





12


in FIG.


2


.











DESCRIPTION OF THE PREFERRED EMBODIMENT




The present invention will now be described by way of an embodiment of the present invention with reference to

FIGS. 1

to


12


. Referring first to

FIG. 1

, a V-shaped multi-cylinder internal combustion engine E carried on a vehicle includes an engine block


15


having first and second cylinder arrays


14


A and


14


B disposed in a V-shape, cylinder heads


16


,


16


coupled to upper ends of the first and second cylinder arrays


14


A and


14


B, and head covers


17


,


17


coupled to the cylinder heads


16


,


16


. Three cylinder bores


18


are provided in a vertical arrangement as viewed on a paper sheet surface of

FIG. 1

in each of the first and second cylinder arrays


14


A and


14


B, and pistons


19


slidably received in the cylinder bores


18


are commonly connected to a single crankshaft


21


by connecting rods


20


, respectively.




The arrangement of the engine E on the side of the first cylinder array


14


A will be described with reference to

FIGS. 2

to


6


. Combustion chambers


22


are defined between the cylinder head


16


and the pistons


19


in the cylinder bores


18


. Provided in the cylinder head


16


at locations corresponding to the combustion chambers


22


are a pair of intake valve bores


23


capable of leading to the combustion chamber


22


, an intake port


24


leading commonly to the intake valve bores


23


and opening into one side of the cylinder head


16


, a pair of exhaust valve bores


25


capable of leading to the combustion chamber


22


, and an exhaust port


26


leading commonly to the exhaust valve bores


25


and opening into the other side of the cylinder head


16


. On the basis of the first and second cylinder arrays


14


A and


14


B forming the V-shape in combination with each other, the cylinder head


16


is disposed, inclined to one of the left and the right in a direction of arrangement of the cylinders, i.e., inclined so that the exhaust port


26


is at a location lower than the intake port


24


.




Stems of intake valve VI, VI as engine valves capable of individually opening and closing the intake valve bores


23


are slidably received in guide tubes


28


provided in the cylinder head


16


. Valve springs


30


for biasing the intake valves VI, VI in a closing direction are mounted between retainers


29


mounted at upper ends of the intake valves VI, VI and the cylinder head


16


. Stems of exhaust valves VE, VE as engine valves capable of individually opening and closing the exhaust valve bores


25


are slidably received in guide tubes


31


provided in the cylinder head


16


. Valve springs


33


for biasing the exhaust valves VE, VE in a closing direction are mounted between retainers


32


mounted at upper ends of the exhaust valves VE, VE and the cylinder head


16


.




The intake valves VI, VI and the exhaust valves VE, VE for every cylinder are opened and closed by a valve operating device


34


A. The valve operating device


34


A includes a camshaft


35


having an axis extending in the direction of arrangement of the cylinders, a pair of rocker shafts


36


and


37


having axes parallel to the camshaft


35


, driving rocker arms


38


and


39


and a free rocker arm


40


, which are swingably carried on one of the rocker shaft


36


for every cylinder, and driving rocker arms


41


,


41


and free rocker arms


42


,


42


, which are swingably carried on the other rocker shaft


37


for every cylinder.




A plurality of (four in the present embodiment) bearing sections


43


are integrally projectingly provided on the cylinder head


16


at distances in the direction of arrangement of the cylinders, so that the adjacent bearing sections sandwich each of the combustion chamber


22


therebetween, and the camshaft


35


is rotatably carried by the bearing sections


43


. Moreover, the camshaft


35


is operatively connected to the crankshaft


21


at a reduction ratio of 1/2.




The pair of the rocker shafts


36


and


37


are fixedly disposed above the camshaft


35


, and a rocker shaft holder


44


is fastened and fixed to upper surfaces of the bearing sections


43


to support the rocker shafts


36


and


37


.




Referring also to

FIG. 7

, the rocker shaft holder


44


includes shaft-supporting sections


44




a


corresponding to the plurality of bearing sections


43


, and a connecting section


44




b


for integrally connecting the shaft-supporting sections


44




a


together. The shaft-supporting sections


44




a


are fastened to the bearing sections


43


on opposite sides of the camshaft


35


by bolts


45


, respectively.




The pair of rocker shafts


36


and


37


are supported on the shaft-supporting sections


44




a


at locations where the camshaft


35


is disposed below and between the rocker shafts


36


and


37


. The rotation of the rocker shafts


36


and


37


about axes are inhibited by engagement of the bolts


45


for fastening the shaft-supporting sections


44




a


to the bearing sections


43


with a portion of an outer surface of each of the rocker shafts


36


and


37


, whereby the rocker shafts


36


and


37


are fixedly supported on the rocker shaft holder


44


.




A flat fastening seats


46


and


47


for fastening the rocker shaft holder


44


is formed on each of the bearing sections


43


on opposite sides of a portion which rotatably supports the camshaft


35


, and the bearing sections


43


are formed to bulge above and between the fastening seats


46


and


47


.




On the other hand, accommodating recesses


48


are provided in lower surfaces of the shaft-supporting sections


44




a


of the rocker shaft holder


44


at locations between the rocker shafts


36


and


37


, so that a portion of a central bulge of the bearing section


43


protrudes into each of the accommodating recesses


48


. The portion of the central bulge of the bearing section


43


is mounted to protrude into each of the accommodating recesses


48


in such a manner that the contact with the rocker shaft holder


44


is avoided, i.e., a gap


49


is defined between the accommodating recess


48


and the bearing section


43


.




Moreover, the connecting section


44




b


of the rocker shaft holder


44


for connecting the shaft-supporting portions


44




a


together is formed to integrally connect at least portions of the shaft-supporting sections


44




a


corresponding to the accommodating recesses


48


to one another.




The rocker shafts


36


and


37


are supported by the shaft-supporting sections


44




a


of the rocker shaft holder


44


, but the rocker shaft


37


on the side of the exhaust valves VE, VE is also supported by shaft-supporting intermediate portions


44




c


integrally provided on the connecting section


44




b


and disposed between the shaft-supporting sections


44




a.






Referring to

FIG. 8

, the driving rocker arms


38


and


39


and the free rocker arm


40


swingably carried on the rocker shaft


36


are disposed in such a manner that the free rocker shaft


40


is interposed between the driving rocker arms


38


and


39


. Tappet screws


54


,


54


are threadedly engaged into the rocker arms


38


and


39


, so that the advanced and retracted positions thereof can be adjusted, and the driving rocker arms


38


and


39


are operatively connected to the intake valves VI, VI by putting the tappet screws


54


,


54


into abutment against upper ends of the intake valves VI, VI.




The driving rocker arms


41


,


41


and the free rocker arms


42


,


42


swingably carried on the rocker shaft


37


are disposed in such a manner that they form pairs at locations spaced apart from each other in an axial direction of the rocker shaft


37


. Tappet screws


55


,


55


are threadedly engaged into the rocker arms


41


,


41


, so that the advanced and retracted positions thereof can be adjusted, and the rocker arms


41


,


41


are operatively connected to the exhaust valves VE, VE by putting the tappet screws


55


,


55


into abutment against upper ends of the exhaust valves VE, VE.




Moreover, the shaft-supporting intermediate portion


44




c


of the rocker shaft holder


44


is disposed between the driving rocker arms


41


,


41


, and the driving rocker arms


41


,


41


are disposed adjacent opposite sides of the shaft-supporting intermediate portion


44




c


in the axial direction of the rocker shaft


37


.




Plug insertion tubes


56


are mounted in the cylinder head


16


, so that they are disposed between the driving rocker arms


41


,


41


. Spark plugs


57


are inserted into the plug insertion tubes


56


and threadedly fitted in the cylinder head


16


to face the combustion chambers


22


.




Referring also to

FIG. 9

, the camshaft


35


is provided with a cam


62


with which a roller


58


supported on the free rocker arm


40


on the side of the intake valves VI, VI is brought into rolling contact, cams


63


,


63


with which rollers


59


,


59


supported on the free rocker arms


42


,


42


on the side of the exhaust valves VE, VE are brought into rolling contact, and a pair of cams


64


,


64


with which cam slippers


60


,


60


provided on the driving rocker arms


38


and


39


on the intake valves VI, VI and cam slippers


61


,


61


provided on the driving rocker arms


41


,


41


on the exhaust valves VE, VE are brought into sliding contact. The cams


62


,


63


,


63


,


64


,


64


are disposed, so that the cams


64


,


64


are interposed between the cam


62


central in the axial direction of the camshaft


35


and the cams


63


,


63


on opposite sides in the axial direction of the camshaft


35


.




Moreover, the cams


62


are provided at locations corresponding to the shaft-supporting intermediate portions


44




c


of the rocker shaft holder


44


, and the rollers


58


in rolling contact with the cams


62


are supported on the free rocker arms


40


on the intake valves VI, VI, so that they are opposed to the shaft-supporting intermediate portions


44




c


. On the other hand, the shaft-supporting intermediate portions


44




c


are provided with notches


53


for avoiding the interference with the rollers


58


, whereby each of the shaft-supporting intermediate portions


44




c


is formed into a substantially J-shape.




The cam


62


is formed to have a cam profile for opening and closing the intake valves VI, VI, and each of the cams


63


,


63


is formed to have a cam profile for opening and closing the exhaust valves VE, VE, but the cams


64


,


64


are formed, so that they substantially close the intake valves VI, VI and the exhaust valves VE, VE to bring them out of operation. Therefore, in a state in which the driving rocker arms


38


and


39


have been connected to the free rocker arm


40


, the intake valves VI, VI can be opened and closed, but in a state in which the connection of the driving rocker arms


38


and


39


to the free rocker arm


40


has been released, the intake valves VI, VI are in substantially closed states and out of operation. In a state in which the driving rocker arms


41


,


41


have been connected to the free rocker arms


42


,


42


, the exhaust valves VE, VE can be opened and closed, but in a state in which the connection of the driving rocker arms


41


,


41


to the free rocker arms


42


,


42


has been released, the exhaust valves VE, VE are in substantially closed states and out of operation.




A valve-operating characteristic changing mechanism


65


is provided in the driving rocker arms


38


and


39


and the free rocker arm


40


on the side of the intake valves VI, VI for changing the connection and disconnection of the driving rocker arms


38


and


39


to and from the free rocker arm


40


.




The valve-operating characteristic changing mechanism


65


includes a connecting pin


67


slidably received in the driving rocker arm


38


and the free rocker arm


40


with one end facing a first hydraulic pressure chamber


66


defined in the driving rocker arm


38


, a connecting pin


68


slidably received in the free rocker arm


40


and the driving rocker arm


39


with one end being in sliding contact with the other end of the connecting pin


67


, a pin


69


with one end being in sliding contact with the other end of the connecting pin


68


and with the other end facing a second hydraulic pressure chamber


70


defined in the driving rocker arm


39


, and a return spring


71


mounted between the driving rocker arm


38


and the connecting pin


67


and accommodated in the first hydraulic pressure chamber


66


.




In the valve-operating characteristic changing mechanism


65


, when a hydraulic pressure is applied to the first hydraulic pressure chamber


66


, the connecting pins


67


and


68


and the pin


69


connected together are moved to a position where the volume of the second hydraulic pressure chamber


70


is smallest, whereby the driving rocker arm


38


and the free rocker arm


40


are connected to each other by the connecting pin


67


, and the free rocker arm


40


and the driving rocker arm


39


are connected to each other by the connecting pin


68


, as shown in FIG.


8


. When a hydraulic pressure is applied to the second hydraulic pressure chamber


70


, the connecting pins


67


and


68


and the pin


69


connected together are moved to a position where the volume of the first hydraulic pressure chamber


66


is smallest, whereby the connection of the driving rocker arm


38


and the free rocker arm


40


is released, because contact faces of the connecting pins


67


and


68


exist between the driving rocker arm


38


and the free rocker arm


40


, and the connection of the free rocker arm


40


and the driving-rocker arm


39


is released, because contact faces of the connecting pin


68


and the pin


69


exist between the free rocker arm


40


and the driving rocker arm


39


.




In this manner, the valve-operating characteristic changing mechanism


65


changes the operating characteristic for the intake valves VI, VI by switching the connection and disconnection of the free rocker arm


40


to and from the driving rocker arms


38


and


39


by the alternative application of the hydraulic pressure to the first and second hydraulic pressure chambers


66


and


70


. The return spring


71


may merely exhibit a spring force enough to be able to avoid the chattering of each of the pins


67


,


68


and


69


in a state in which no hydraulic pressure is applied to any of the first and second hydraulic pressure chambers


66


and


70


in response to the stoppage of the operation of the engine E.




A dividing member


72


is received in the rocker shaft


36


for dividing the inside of the rocker shaft


36


into two portions, so that a first working oil passage


73


leading to the first hydraulic pressure chamber


66


and a second working oil passage


74


leading to the second hydraulic pressure chamber


70


are defined independently in the rocker shaft


36


by the dividing member


72


.




Valve-operating characteristic changing mechanisms


75


,


75


are provided in the driving rocker arms


41


,


41


and the free rocker arms


42


,


42


disposed adjacently to form pairs on the side of the exhaust valves VE, VE for changing the connection and disconnection of the driving rocker arms


41


,


41


to and from the free rocker arms


42


,


42


.




Each of the valve-operating characteristic changing mechanism


75


includes a connecting pin


77


slidably received in the driving rocker arm


41


and the free rocker arm


42


with one end facing a first hydraulic pressure chamber


76


defined in the driving rocker arm


41


, a pin


78


slidably received in the free rocker arm


42


with one end being in sliding contact with the other end of the connecting pin


77


and with other end facing a hydraulic pressure chamber


79


defined in the free rocker arm


42


, and a return spring


80


mounted between the driving rocker arm


41


and the connecting pin


77


and accommodated in the first hydraulic pressure chamber


76


.




In the valve-operating characteristic changing mechanism


75


, when a hydraulic pressure is applied to the first hydraulic pressure chamber


76


, the connecting pin


77


and the pin


78


connected to each other are moved to a position where the volume of the second hydraulic pressure chamber


79


is smallest, whereby the driving rocker arm


41


and the free rocker arm


42


, as shown in FIG.


8


. When a hydraulic pressure is applied to the second hydraulic pressure chamber


79


, the connecting pin


77


and the pin


78


connected to each other are moved to a position where the volume of the first hydraulic pressure chamber


76


is smallest, whereby the connection of the free rocker arm


42


and the driving rocker arm


41


is released, because contact faces of the connecting pin


77


and the pin


78


exist between the free rocker arm


42


and the driving rocker arm


41


.




In this manner, the valve-operating characteristic changing mechanism


75


changes the operating characteristic for the exhaust valves VE, VE by switching the connection and disconnection of the driving rocker arm


41


and the free rocker arm to and from each other by the alternative application of the hydraulic pressure to the first and second hydraulic pressure chambers


76


and


79


. The return spring


80


may merely exhibit a spring force enough to be able to avoid the chattering of each of the pins


77


and


78


in a state in which no hydraulic pressure is applied to any of the first and second hydraulic pressure chambers


76


and


79


in response to the stoppage of the operation of the engine E.




A dividing member


82


is received in the rocker shaft


37


for dividing the inside of the rocker shaft


37


into two portions, so that a first working oil passage


83


leading to the first hydraulic pressure chamber


76


and a second working oil passage


84


leading to the second hydraulic pressure chamber


79


are defined independently in the rocker shaft


37


by the dividing member


82


.




Lost motion springs


85


are mounted between the cylinder head


16


and the free rocker arms


40


for exhibiting a spring force for urging the free rocker arm


40


to the cam


62


of the camshaft


35


in a state in which the valve-operating characteristic changing mechanism


65


on the side of the intake valves VI, VI has released the connection of the free rocker arm


40


to the driving rocker arms


38


and


39


. A portion of each of the spring


85


is accommodated in each of bottomed holes


86


provided in the upper surface of the cylinder head


16


.




Lost motion springs


87


are mounted between the rocker shaft holder


44


and the free rocker arms


42


for exhibiting a spring force for urging the free rocker arms


42


,


42


to the cams


63


,


63


of the camshaft


35


in a state in which the valve-operating characteristic changing mechanisms


75


,


75


on the side of the exhaust valves VE, VE have released the connection of the free rocker arms


42


,


42


to the driving rocker arms


41


,


41


. Bottomed cylindrical tubes


88


are integrally provided on the connecting section


44




b


of the rocker shaft holder


44


to protrude upwards from the rocker shaft holder


44


, so that a portion of each of the springs


87


is accommodated in each of the bottomed cylindrical tubes


88


.




The lost motion springs


87


each having the portion accommodated in each of the bottomed cylindrical tubes


88


cannot be fallen from the rocker shaft holder


44


in a state in which the rocker shaft


37


swingably carrying the driving rocker arms


41


and the free rocker arms


42


has been supported in the rocker shaft holder


44


. Thus, the lost motion springs


87


can be retained on the rocker shaft holder


44


in an extremely simple structure in which they are only partially accommodated in the bottomed cylindrical tubes


88


.




Moreover, the bottomed cylindrical tubes


88


are integrally provided on the rocker shaft holder


44


to protrude therefrom, so that they are connected to the shaft-supporting sections


44




a


, and the rigidity of the shaft-supporting sections


44




a


and in turn the rigidity of the entire rocker shaft holder


44


can be increased by the bottomed cylindrical tubes


88


.




Referring also to

FIG. 10

, a hydraulic pressure control valve unit


90


is mounted to the cylinder head


16


at one end in the direction of arrangement of the cylinders for controlling the hydraulic pressure of the working oil supplied to the first working oil passages


73


and


83


and the second working oil passages


74


and


84


defined in the rocker shafts


36


and


37


.




The hydraulic pressure control valve unit


90


comprises a valve spool


91


mounted to the cylinder had


16


, and a solenoid valve


92


mounted to the spool valve


91


for controlling the switching operation of the spool valve


91


. A passage-defining member


93


is mounted on the cylinder head


16


between the spool valve


91


and the rocker shaft holder


44


, and one end of each of the rocker shafts


36


and


37


is fitted into the passage-defining member


93


.




Referring also to

FIG. 11

, the passage-defining member


93


is provided with a first communication oil passage


94


connecting the first working oil passages


73


and


83


in the rocker shafts


36


and


37


and the spool valve


91


to each other, and a second communication oil passage


95


connecting the second working oil passages


74


and


84


in the rocker shafts


36


and


37


and the spool valve


91


to each other. The spool valve


91


is capable of being switched between a first state in which it permits the working oil from a hydraulic pressure source (not shown) to be passed to the first communication oil passage


94


and thus to the first working oil passages


73


and


83


, and a second state in which it permits the working oil from the hydraulic pressure source to be passed to the second communication oil passage


95


and thus to the second working oil passages


74


and


84


.




Moreover, the spool valve


91


is designed to discharge a drain oil upon the switching thereof between the first and second states, and a drain oil passage


96


for guiding the drain oil is provided in an upper portion of the passage-defining member


93


.




On the other hand, an oil sump


97


is defined in the upper surface of the rocker shaft holder


44


, so that the oil scattered within the valve-operating chamber between the cylinder head


16


and the head cover


17


can be reserved in the oil sump.




The oil sump


97


includes a groove portion


98


extending in the direction of arrangement of the cylinders and substantially T-shaped groove branches


99


which are disposed between the pair of bottomed cylindrical tubes


88


,


88


at locations corresponding to the centers of the combustion chambers


22


and which are connected to the groove portion


98


. The groove branches


99


are formed, so that they are connected to the side of the groove portion


98


adjacent the exhaust valves VE, VE in order to guide the oil in the groove portion


98


toward the groove branches


99


, on the basis of the cylinder


16


being disposed, inclined so that the exhaust port


26


is located below the intake port


23


.




Referring also to

FIGS. 6 and 12

, a rib


101


is projectingly provided on the upper surface of the rocker shaft holder


44


to extend in the direction of arrangement of the cylinders. The rib


101


has a side face located below the groove portion


98


and connected flush to peripheral walls of ends of the groove branches


99


. The rib


101


connects those portions of the bottomed cylindrical tubes


88


,


88


disposed on opposite sides of the groove branches


99


, which are located at lower sides in a direction of inclination of the cylinder head


16


. The bottomed cylindrical rubes


88


,


88


and the rib


101


are disposed in a substantially U-shape to constitute a portion of the oil sump


97


, and the rib


101


is a wall defining a lowermost portion of the oil sump


97


.




Lubricating oil passages


100


are provided in the rocker shaft holder


44


to vertically extend through the connecting section


44




b


along the side face of the rib


101


adjacent the oil sump


97


. Upper ends of the lubricating oil passages


100


communicate in pairs with ends of the groove branches


99


which are portions of the oil sump


97


closer to the ribs


101


, i.e., with the oil sump


97


in a region surrounded by the bottomed cylindrical tubes


88


,


88


and the rib


101


.




The lubricating oil passages


100


forming each pair are disposed at locations where the shaft-supporting intermediate portion of the rocker shaft holder


44


is interposed between them. A lubricating oil is supplied from the lubricating oil passages


100


,


100


for lubricating slide portions between the shaft-supporting intermediate portion


44




c


and those


41


,


41


of the rocker arms


38


to


40


,


41


and


42


adjoining the shaft-supporting intermediate portion


44




c


, slide portions between the driving rocker arms


41


,


41


and the rocker shaft


37


and slide portions between the free rocker arms


42


,


42


adjoining the driving rocker arms


41


,


41


and the rocker shaft


37


.




A rib


102


is projectingly provided on the upper surface of the rocker shaft holder


44


to extend in the direction of arrangement of the cylinders, so that the oil sump


97


is interposed between the rib


101


and the rib


102


. Moreover, the ribs


101


and


102


are provided over the longitudinal entire length of the rocker shaft holder


44


, and the shaft-supporting sections


44




a


and the shaft-supporting intermediate portions


44




c


of the rocker shaft holder


44


are interconnected by the ribs


101


and


102


.




The drain oil discharged from the hydraulic pressure control valve unit


90


is also guided to the oil sump


97


, and an upper portion of the passage-defining member


93


interposed between the hydraulic pressure control valve unit


90


and the rocker shaft holder


44


is formed to permit the drain oil discharged from the hydraulic pressure control valve unit


90


to be delivered to the oil sump


97


.




More specifically, the upper portion of the passage-defining member


93


is provided with a recess


103


with which the drain oil passage


96


for guiding the drain oil from the hydraulic pressure control valve unit


90


communicate, and a substantially U-shaped guide


104


which opens upwards to guide the drain oil accumulated in the recess


103


toward the oil sump


97


. The guide


104


is extended from the passage-defining member


93


to above one end of the groove portion


98


of the oil sump


97


.




The arrangement of the second cylinder array


14


B is basically the same as the arrangement of the first cylinder array


14


A, but a valve-operating device


34


B for driving the intake valves VI and the exhaust valves VE provided in the cylinder head


16


on the second cylinder array


14


B is different from the valve-operating device


34


A on the first cylinder array


14


A in that the valve-operating device


34


B does not close the intake valves VI and the exhaust valves VE to stop their operation during operation of the engine E.




The operation of this embodiment will be described below. The bearing sections


43


rotatably carrying the camshaft


35


are projectingly provided on the cylinder head


16


at distances spaced apart from one another in the direction of arrangement of cylinders in such a manner that each of the combustion chambers


22


is defined between the adjacent bearing sections


43


. On the other hand, the rocker shafts


36


and


37


disposed above the camshaft


35


to swingably carry the rocker arms


38


,


39


,


40


,


41


and


42


rotated with the rotation of the camshaft


35


are fixedly supported by the rocker shaft holder


44


fastened to the bearing sections


43


and thus, the support rigidity of the rocker shaft


36


and


37


can be enhanced.




The rocker shaft holder


44


includes the shaft-supporting sections


44




a


fastened to the bearing sections


43


, and the connecting section


44




b


connecting the shaft-supporting sections


44




a


together, and the accommodating recesses


48


are provided in the lower surfaces of the shaft-supporting sections


44




a


, so that the bearing sections


43


partially protrude into the accommodating recesses


48


. Thus, the structure of fastening of the bearing sections


43


and the rocker shaft holder


44


to each other can be constructed compactly in the direction along the axes of the cylinder bores


18


to avoid an increase in size of the engine E. Moreover, the connecting section


44




b


integrally connects at least portions of the, shaft-supporting sections


44




a


corresponding to the accommodating recesses


48


to one another and hence, a reduction in rigidity of the rocker shaft holder


44


can be avoided in spite of the provision of the accommodating recesses


48


in the shaft-supporting sections


44




a.






The bearing sections


43


partially protrude into the accommodating recesses


48


to avoid the contact with the rocker shaft holder


44


and hence, it is possible to inhibit the vibration of the camshaft


35


to the utmost from being transmitted through the rocker shaft holder


44


to the rocker shafts


36


and


37


.




In addition, the pair of rocker shafts


36


and


37


parallel to each other are supported on the rocker shaft holder


44


, and the accommodating recesses


48


are provided in the rocker shaft holder


44


between the rocker shafts


36


and


37


. Thus, the structure of fastening between the bearing sections


43


and the rocker shaft holder


44


to each other can be constructed further compactly in the direction along the axes of the cylinder bores


18


in such a manner that the distances between the rocker shafts


36


and


37


and the camshaft


35


can be shortened.




The connecting section


44




b


of the rocker shaft holder


44


is integrally provided with the shaft-supporting intermediate portions


44




c


disposed between the shaft-supporting sections


44




a


, and one


37


of the rocker shafts


36


and


37


is supported not only by the shaft-supporting sections


44




a


but also by the shaft-supporting intermediate portions


44




c


. Thus, the support rigidity of the rocker shaft


37


can be enhanced sufficiently.




Additionally, the shaft-supporting intermediate portions


44




c


are provided with the notches


53


adapted to avoid the interference with the rollers


58


supported on the free rocker arm


40


on the side of the intake valves VI, VI and opposed to the shaft-supporting intermediate portions


44




c


, and the free rocker arm


40


provided with the roller


58


can be disposed in sufficient proximity to the rocker shaft


37


in spite of the existence of the shaft-supporting intermediate portions


44




c


, whereby the valve-operating devices


34


A and


34


B including the free rocker arm


40


and the rocker shaft


37


can be constructed compactly.




Moreover, the driving rocker arms


41


,


41


on the exhaust valves VE, VE are disposed adjacent the shaft-supporting intermediate portions


44




c


in the axial direction of the rocker shaft


37


. Therefore, it is possible to inhibit the axial movement of the driving rocker arm


41


by the shaft-supporting intermediate portions


44




c


and hence, a part exclusively for limiting the axial movement of the driving rocker arm


41


is nor required, leading to a reduction in number of parts.




The oil sump


97


is defined in the upper surface of the rocker shaft holder


44


, and the lubricating oil passages


100


are provided in the rocker shaft holder


44


, so that the lubricating oil can be supplied to the slide portions of the driving rocker arm


41


and the free rocker arm


42


which are two of the rocker arms


38


to


40


,


41


and


42


relative to the rocker shaft


37


and the slide portions between the shaft-supporting intermediate portions


44




c


and the driving rocker arm


41


. Therefore, the oil accumulated in the oil sump


97


can be reliably supplied from the oil sump through the lubricating oil passages


100


to the slide portions of the driving rocker arm


41


and the free rocker arm


42


relative to the rocker shaft


37


and the slide portions between the shaft-supporting intermediate portions


44




c


and the driving rocker arm


41


to positively lubricate such slide portions. Thus, a part exclusively for lubricating the slide portions between the driving rocker arm


41


and the free rocker arm


42


and the slide portions between the shaft-supporting intermediate portions


44




c


and the driving rocker arm


41


is not required, and the slide portions can be lubricated, while avoiding an increase in number of parts. Moreover, the oil sump


97


is defined in the upper surface of the rocker shaft holder


44


and hence, can be formed easily.




The oil sump


97


is formed in the upper surface of the rocker shaft holder


44


and provided with the groove portion


98


extending the direction of arrangement of the cylinders, and the groove branches


99


connected to the groove portion


98


. The rib


101


is projectingly provided in the rocker shaft holder


44


to extend in the direction of arrangement of the cylinders, and has the side face connected flush to a portion of the peripheral wall of the oil sump


97


, i.e., the peripheral walls of the ends of the groove branches


99


. In addition, the lubricating oil passages


100


are provided in the rocker shaft holder


44


in such manner that their upper ends communicate with a portion of the oil sump


97


closer to the rib


101


(the ends of the groove branches


99


in the present embodiment) and they extend through the rocker shaft holder


44


along the side face of the rib


101


adjacent the oil sump


97


. Therefore, it is possible to compensate for a reduction in rigidity of the rocker shaft holder


44


due to the provision of the lubricating oil passages


100


, while enabling the supplying of the oil in the oil sump


97


to each of the cylinders.




The cylinder head


16


is disposed in the inclined state with the exhaust port


26


located below the intake port, and the rib


101


is projectingly provided on the upper surface of the rocker shaft holder


44


below the groove portion


98


. Therefore, the rib


101


enhancing the rigidity of the rocker shaft holder


44


can function as the wall defining the lower portion of the oil sump


97


, and a larger amount of the oil can be positively stored on the upper surface of the rocker shaft holder


44


.




In addition, the rocker shaft holder


44


includes the bottomed cylindrical tubes


88


integrally provided on the upper surface thereof and having the lost motion springs


87


accommodated therein for biasing the free rocker arm


42


on the side of the exhaust valves VE, VE toward the cam


63


of the camshaft


35


, and the rib


101


also integrally provided on the upper surface thereof to connect the bottomed cylindrical tubes


88


to one another, and a portion of the oil sump


97


is defined by the bottomed cylindrical tubes


88


and the rib


101


. Therefore, it is possible to increase the rigidity of the rocker shaft holder


44


by the bottomed cylindrical tubes


88


and the rib


101


, and to define a portion of the oil sump


97


in the upper surface of the rocker shaft holder


44


. Particularly, as in the present embodiment, it is possible to further increase the rigidity of the rocker shaft holder


44


by interconnecting the bottomed cylindrical tubes


88


and the rib


101


to form a substantially U-shape.




The lubricating oil passages


100


are provided in the rocker shaft holder


44


in such manner that the upper ends of the lubricating oil passages


100


communicate with the oil sump


97


in the region surrounded by the bottomed cylindrical tubes


88


and the rib


101


, and hence, the upper ends of the lubricating oil passages


100


communicate with the portions having the increased rigidity. Therefore, it is possible to avoid a reduction in rigidity of the rocker shaft holder


44


due to the provision of the lubricating oil passages


100


.




The rib


102


is also projectingly provided on the upper surface of the rocker shaft holder


44


to extend in the direction of arrangement of the cylinders, so that the oil sump


97


is interposed between the ribs


101


and


102


. The rigidity of the rocker shaft holder


44


, and in turn the support rigidity of the rocker shafts


36


and


37


can be enhanced even by the rib


102


.




Further, since the ribs


101


and


102


connect the shaft-supporting sections


44




a


and the shaft-supporting intermediate portions


44




c


in the rocker holder


44


to one another, it is possible to enhance the rigidity of the rocker shaft holder


44


, particularly, the rigidity of the shaft-supporting intermediate portions


44




c


by the ribs


101


and


102


, and in turn to further enhance the support rigidity of the rocker shaft


37


.




The hydraulic pressure control valve unit


90


is mounted to the cylinder head


16


and capable of controlling the pressure of the working oil supplied to the valve-operating characteristic changing mechanism


65


provided in the rocker arms


38


to


40


on the intake valves VI, VI and the valve-operating characteristic changing mechanism


75


provided in the rocker arms


41


and


42


on the side of the exhaust valves VE, VE, and the drain oil discharged from the hydraulic pressure control valve unit


90


is guided to the oil sump


97


. Therefore, the drain oil discharged from the hydraulic pressure control valve unit


90


can be also passed to the slide portions of the rocker arms


41


and


42


on the side of the exhaust valves VE, VE and utilized to lubricate the slide portions, and hence, it is unnecessary to provide other special lubricating oil passages. Moreover, the hydraulic pressure control unit


90


discharges only the drain oil upon the switching operation of the valve-operating characteristic changing mechanisms


65


and


75


, and a reduction in pressure of the working oil supplied to the valve-operating characteristic changing mechanisms


65


and


75


cannot occur, and the responsiveness of the hydraulic pressure control valve unit


90


cannot be reduced, due to the utilization of the drain oil for the lubrication.




The passage-defining member


93


having the first and second communication passages


94


and


95


interconnecting the first working oil passages


73


and


83


and the second working oil passages


74


and


84


defined respectively in the rocker shafts


36


and


37


is interposed between the hydraulic pressure control valve unit


90


and the rocker shaft holder


44


, and the upper portion of the passage-defining member


93


is formed to enable the delivery of the drain oil to the oil sump


97


. Therefore, a part exclusively for delivering the drain oil between the hydraulic pressure control valve unit


90


and the oil sump


97


is not required.




Further, the upper portion of the passage-defining member


93


is provided with the recess


103


for receiving the drain oil from the hydraulic pressure control valve unit


90


, and the guide


104


for guiding the drain oil accumulated in the recess


103


toward the oil sump


97


. The guide


104


is extended from the passage-defining member


93


to above one end of the groove portion


98


of the oil sump


97


. Therefore, the drain oil can be reliably delivered from passage-defining member


93


to the oil sump


97


in the rocker shaft holder


44


, and a sufficient amount of the drain oil can be supplied to the oil sump


97


to perform the sufficient lubrication.




The bearing sections


43


are integrally provided on the cylinder head


16


in the above-described embodiment, but the present invention is also applicable to an internal combustion engine in which bearing sections separate from a cylinder head


16


are provided on the cylinder head


16


. In addition, the passage-defining member


93


separate from the hydraulic pressure control valve unit


90


is interposed between the hydraulic pressure control valve unit


90


and rocker shaft holder


44


in the embodiment, but the passage-defining member may be provided integrally on the hydraulic pressure control valve unit


90


and in this case, the number of parts can be reduced.




Although the embodiment of the present invention has been described in detail, it will be understood that the present invention is not limited to the above-described embodiments, and various modifications in design may be made without departing from the spirit and scope of the invention defined in the claims.



Claims
  • 1. An internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head, and rocker arms moved with the rotation of said camshaft and swingably carried on rocker shafts,wherein a rocker shaft holder fastened and fixed to said bearing sections to support said rocker shafts is provided with accommodating recesses into each of which a portion of each of said bearing sections protrudes.
  • 2. An internal combustion engine according to claim 1, wherein a portion of each of said bearing sections protrudes into each of said accommodating recesses to avoid the contact with said rocker shaft holder.
  • 3. An internal combustion engine according to claim 2, wherein the plurality of rocker shafts parallel to one another are supported on said rocker shaft holder, and said accommodating recesses are provided in said rocker shaft holder between said rocker shafts.
  • 4. An internal combustion engine according to claim 3, wherein said rocker shaft holder includes a plurality of shaft-supporting sections fastened to the plurality of bearing sections and provided with said accommodating recesses, respectively, and a connecting section which integrally connects at least portions of said shaft-supporting sections corresponding to said accommodating recesses to one another.
  • 5. An internal combustion engine according to claim 2, wherein said rocker shaft holder includes a plurality of shaft-supporting sections fastened to the plurality of bearing sections and provided with said accommodating recesses, respectively, and a connecting section which integrally connects at least portions of said shaft-supporting sections corresponding to said accommodating recesses to one another.
  • 6. An internal combustion engine according to claim 1, wherein the plurality of rocker shafts parallel to one another are supported on said rocker shaft holder, and said accommodating recesses are provided in said rocker shaft holder between said rocker shafts.
  • 7. An internal combustion engine according to claim 6, wherein said rocker shaft holder includes a plurality of shaft-supporting sections fastened to said plurality of bearing sections and provided with said accommodating recesses, respectively, and a connecting section which integrally connects at least portions of said shaft-supporting sections corresponding to said accommodating recesses to one another.
  • 8. An internal combustion engine according to claim 1, wherein said rocker shaft holder includes a plurality of shaft-supporting sections fastened to said plurality of bearing sections and provided with said accommodating recesses, respectively, and a connecting section which integrally connects at least portions of said shaft-supporting sections corresponding to said accommodating recesses to one another.
  • 9. An internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head; and a rocker shaft holder which includes a plurality of shaft-supporting sections fastened to upper surfaces of said plurality of bearing sections, respectively, and a connecting section integrally connecting said shaft-supporting sections to one another and which supports a rocker shaft swingably carrying thereon rocker arms and moved with the rotation of said camshaft,wherein said rocker shaft is supported on the shaft-supporting sections and also on shaft-supporting intermediate portions which are integrally provided on the connecting section and each disposed between the adjacent shaft-supporting sections.
  • 10. An internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head: and a rocker shaft holder which includes a plurality of shaft-supporting sections fastened to said plurality of bearing sections, respectively, and a connecting section integrally connecting said shaft-supporting sections to one another and which supports a rocker shaft swingably carrying thereon rocker arms and moved with the rotation of said camshaft,wherein said rocker shaft is supported on the shaft-supporting sections and also on shaft-supporting intermediate portions which are integrally provided on the connecting section and each disposed between the adjacent shaft-supporting sections, and wherein the rocker shaft supported on said shaft-supporting intermediate portions and another rocker shaft having an axis parallel to said rocker shaft are supported on said rocker shaft holder, and a roller in rolling contact with a cam provided on said camshaft is supported on each of rocker arms swingably carried on said other rocker shaft at locations corresponding to said shaft-supporting intermediate portions so that they are opposed to said shaft-supporting intermediate portions, and each of said shaft-supporting intermediate portions is provided with a notch for avoiding the interference with said roller.
  • 11. An internal combustion engine according to claim 10, wherein rocker arms disposed adjacent said shaft-supporting intermediate portions are swingably carried on the rocker shaft supported on said shaft-supporting intermediate portions.
  • 12. An internal combustion engine according to claim 11, wherein said rocker shaft: holder is integrally provided with ribs which extend in a direction parallel to the axis of said rocker shaft and connects said shaft-supporting sections and said shaft-supporting intermediate portions to each other.
  • 13. An internal combustion engine according to claim 11, wherein said rocker shaft holder has an oil sump defined in its upper surface, and lubricating oil passages provided therein for guiding a lubricating oil from said oil sump to slide portions between said shaft-supporting intermediate portions and said rocker arms adjoining said shaft-supporting intermediate portions.
  • 14. An internal combustion engine according to claim 10, wherein said rocker shaft holder is integrally provided with ribs which extend in a direction parallel to the axis of the rocker shaft and connects said shaft-supporting sections and said shaft-supporting intermediate portions to each other.
  • 15. An internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head: and a rocker shaft holder which includes a plurality of shaft-supporting sections fastened to said plurality of bearing sections, respectively, and a connecting section integrally connecting said shaft-supporting sections to one another and which supports a rocker shaft swingably carrying thereon rocker arms and moved with the rotation of said camshaft,wherein said rocker shaft is supported on the shaft-supporting sections and also on shaft-supporting intermediate portions which are integrally provided on the connecting section and each disposed between the adjacent shaft-supporting sections, and wherein the rocker arms disposed adjacent the shaft-supporting intermediate portions are swingably carried on said rocker shaft supported on said shaft-supporting intermediate portions.
  • 16. An internal combustion engine according to claim 15, wherein the rocker shaft holder is integrally provided with ribs which extend in a direction parallel to the axis of the rocker shaft and connects said shaft-supporting sections and said shaft-supporting intermediate portions to each other.
  • 17. An internal combustion engine according to claim 15, wherein said rocker shaft holder has an oil sump defined in its upper surface, and lubricating oil passages provided therein for guiding a lubricating oil from said oil sump to slide portions between said shaft-supporting intermediate portions and said rocker arms adjoining said shaft-supporting intermediate portions.
  • 18. An internal combustion engine including bearing sections rotatably carrying a camshaft and provided integrally or separately on a cylinder head; and a rocker shaft holder which includes a plurality of shaft-supporting sections fastened to said plurality of bearing sections, respectively, and a connecting section integrally connecting said shaft-supporting sections to one another and which supports a rocker shaft swingably carrying thereon rocker arms and moved with the rotation of said camshaft,wherein said rocker shaft is supported on the shaft-supporting section and also on shaft-supporting intermediate portions which are integrally provided on the connecting section and each disposed between the adjacent shaft-supporting sections, and wherein said rocker shaft holder is integrally provided with ribs which extend in a direction parallel to the axis of the rocker shaft and connects said shaft-supporting sections and said shaft-supporting intermediate portions to each other.
Priority Claims (1)
Number Date Country Kind
2000-355903 Nov 2000 JP
US Referenced Citations (5)
Number Name Date Kind
5339778 Reckzugel et al. Aug 1994 A
5617818 Luders Apr 1997 A
5651337 Regueiro Jul 1997 A
6098581 Buck et al. Aug 2000 A
6234126 Kaye May 2001 B1
Foreign Referenced Citations (4)
Number Date Country
6-17613 Jan 1994 JP
2688732 Aug 1997 JP
10-148113 Jun 1998 JP
WO 9928602 Jun 1999 WO
Non-Patent Literature Citations (1)
Entry
Takahashi et al., Lubricating Structure in Internal Combustion Engine, U.S. patent application Publication, US 2002/0062811 A1, May 30, 2002.