Abstract:
A roller rocker mounting mechanism for an internal combustion engine valve actuating mechanism includes a first rocker stand having a first locating boss and a second rocker stand having a second locating boss. An indexing link has a first portion separably attachable to the first locating boss and a second portion separably attachable to the second locating boss to connect the first rocker stand and the second rocker stand in a manner that prevents rotation of either rocker stand when the rocker stands are attached to the cylinder head.

Description:
[0001]    This application claims priority to U.S. Patent Application No. 60/368,535, to Daniel Jesel, filed Apr. 1, 2002, entitled Roller Rocker Mounting Mechanism, which application is incorporated by reference herein. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to internal combustion engine overhead valve rocker mechanisms.  
           [0003]    In certain pushrod type overhead valve engines, such as the Chevrolet® big block, the rocker arms will be attached to the head by a simple stud mechanism screwed into the head. The rocker stud will maintain the rocker in the desired position and allow the rocker to rock about the stud in response to movement from the attached pushrod to actuate the respective valve. However, the rocker stud cannot effectively prevent the rocker from rotating about a longitudinal axis of the rocker stud. Therefore, to prevent such rotation and the resulting misalignment of the rocker with the valve stem, pushrod guides are used in the engine to generally fix the positioning of the pushrods. The pushrods are allowed to move up and down in response to rotation of the camshaft but are prevented from substantial side-to-side movement. This general fixing of the pushrods by the pushrod guides helps prevent rotation of the rockers about the rocker studs.  
           [0004]    High performance versions of such engines will often use roller rocker arms. A rocker stand is mounted to the head, usually by bolting the stand to the same threaded bores as the rocker studs use. The rocker stand supports a shaft mounted transversely to the rocker stand mounting bolt and the roller rocker arms are mounted by roller bearings on the shaft. This roller bearing mounting of the rocker arm is more efficient and can better withstand higher actuating forces found in high performance engines than can a standard rocker arm. Since the rocker stands are mounted to the head by the single bolt, they are subject to rotation about the bolt. The shaft is usually fixed to the rocker stand at both ends and so the roller rocker arm will also rotate with the rocker stand about the mounting bolt. Therefore, some provision must be made to prevent rotation of each rocker stand and respective roller rocker.  
           [0005]    One approach to preventing rotation of the rocker stands has been to mount several roller rockers on an extended rocker stand. However, such rocker stands are complex, expensive to manufacture and not easily set up. Also, substantial machining of the cylinder head is required to accommodate such stands. See FIG. 7 (Prior Art) which shows a portion of such a known multiple rocker stand which supports four roller rockers, two of which are needed for each big block cylinder head.  
           [0006]    Another approach has been to bolt adjacent rocker arms together to prevent rotation. See FIG. 8 (Prior Art) which shows such a known pair of rocker assemblies  110  and  112 . Each of the rocker assemblies  110  and  112  include a tab  114  and  116 , respectively, which can be bolted together by bolt  118  to prevent rotation of the rocker stands. While this method is effective in preventing rotation of the rocker roller, it is also expensive as it requires different intake and exhaust rocker stands. Further, because of the canting of the rocker stands, if tight tolerances are not maintained, or the rocker stands are shimmed at all, the geometry of the two rocker stands with respect to each other can change enough such that the bolt  118  cannot be passed through one or both of the tabs to allow the rocker stands to be bolted together. This may then require further expensive and time-consuming machining of the rocker stands and/or cylinder head to provide the desired dimensions and tolerances.  
           [0007]    In addition, it has been found that many aftermarket cylinder heads are not machined to the proper dimensions. When roller rocker components having correct dimensions are installed on such cylinder heads, the components may not have the correct geometry to operate properly. Although the roller rocker components are correct and it is the cylinder head that is incorrect, the purchaser tends to assume the opposite, leading to poor customer relations that are unjustified for the supplier of the roller rocker components.  
           [0008]    Therefore, a simple, cost effective mechanism is needed for mounting rocker roller arms to a cylinder head while preventing rotation of the rocker roller arms about a rocker stand mounting bolt. Such a mechanism should be able to operate properly even when the dimensions of the cylinder head are beyond design tolerances.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention is a roller rocker mounting mechanism for mounting a roller rocker to a cylinder head. It includes an indexing link for accurately positioning and aligning a pair of identical rocker stands on adjacent rocker mounting bosses, allowing independent height adjustment of each rocker stand while preventing rotation of the rocker stands and the respective roller rockers. The mechanism is compact, simple and inexpensive to manufacture and allows a single rocker stand to be used for both intake and exhaust valves, as well as for various valve height configurations. This reduces the need for numerous rocker stand configurations of more complex and expensive configurations.  
           [0010]    It is a specific object of the present invention to provide a roller rocker mounting mechanism that prevents rotation of the rocker stand and roller rocker about mounting bolt axis.  
           [0011]    It is a further object of the present invention to provide a roller rocker mounting mechanism that utilizes and anti-rotationally connects a pair of identical or substantially identical rocker stands.  
           [0012]    It is a further object of the present invention to provide a roller rocker mounting mechanism that provides a simple, manual and independent height adjustment of each rocker stand of the mechanism by the engine assembler without requiring machining of any components.  
           [0013]    It is a further object of the present invention to provide a roller rocker mounting mechanism that allows a pair of separate rocker stands to be accurately aligned with one another.  
           [0014]    It is a further object of the present invention to provide a roller rocker mounting mechanism that allows use of a single configuration of rocker stand to be used for both intake and exhaust valves of an engine, as well as for different valve height configurations in the same or different engine(s).  
           [0015]    It is a further object of the present invention to provide a roller rocker mounting mechanism that can be used in different engine configurations by the simple change of an indexing link tying together two or more rocker stands.  
           [0016]    It is a further object of the present invention to provide a roller rocker mounting mechanism that is compact, simple and inexpensive to manufacture.  
           [0017]    It is a further object of the present invention to provide a roller rocker mounting mechanism that reduces the number of total components required to apply the mechanism to a variety of different engines.  
           [0018]    The invention is more fully described in combination with the accompanying drawings, in which, like reference numerals indicate like components. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 (Prior Art) is a partial perspective view of a Chevrolet® big block cylinder head:  
         [0020]    [0020]FIG. 2 is a perspective view of an indexing link of the present invention positioned on mounting bosses of the cylinder head of FIG. 1;  
         [0021]    [0021]FIG. 3 is a perspective view of a pair of rocker stands of the present invention mounted over the indexing link shown in FIG. 2;  
         [0022]    [0022]FIG. 4 shows a bottom perspective view of a pair of rocker stands engaged with the indexing link;  
         [0023]    [0023]FIG. 5 shows a pair of roller rockers mounted on the rocker stands shown in FIG. 3;  
         [0024]    [0024]FIGS. 6 a - e  show further views of the indexing link of the present invention;  
         [0025]    [0025]FIG. 7 (Prior Art) is a partial perspective view of a known multiple roller rocker stand; and  
         [0026]    [0026]FIG. 8 (Prior Art) is a perspective view of a known pair of roller rocker stands. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    [0027]FIG. 1 (Prior Art) shows a portion of a Chevrolet® big block cylinder head  10  with a plurality of intake valve assemblies  12  and exhaust valve assemblies  14  installed. As can be seen, the intake valves  12  are canted with respect to the exhaust valves  14 . A plurality of mounting bosses  16  are provided, each having a threaded bore  18  for mounting the intake rocker arms to the cylinder head  10 . In a conventional head with non-roller rocker arms, each intake rocker arm would be mounted to its respective mounting boss  16  by a rocker stud threaded into bore  18 . Similarly, a plurality of mounting bosses  20  are provided, each having a threaded bore  22  for mounting the exhaust rocker arms to the cylinder head  10 . As can be seen, the mounting bosses  18  are relatively lower than the mounting bosses  20 , as well as being canted similarly to the canting of the intake valves. This configuration of the cylinder head  10  is known, as are other details, which are not necessary to discuss herein.  
         [0028]    [0028]FIG. 2 shows a rocker arm indexing link  30  of the present invention positioned on adjacent mounting bosses  18  and  20 . The indexing link  30  includes an intake end  32 , an exhaust end  34  and an interconnecting bar  36 . Each of the ends has a generally circular outer shape to fit well within the conventionally machined areas of the cylinder head  10  forming the respective mounting bosses  18  and  20 . In this manner, additional machining of the cylinder head is not required to fit the indexing link  30 . The respective ends  32  and  34  include generally square or rectangular locating bores  38  and  40 , respectively. The locating bores  38  and  40  can also have other shapes. The use of appropriately aligned asymmetrical shapes for the bores  38  and  40 , and the respective locating bosses  52  can help assure correct assembly of the roller rocker mounting mechanism to the cylinder head  10 .  
         [0029]    In the preferred embodiment, the indexing link  30  is configured as a formed sheet metal stamping having a generally uniform thickness. Such a part is quick and inexpensive to manufacture. The indexing link is configured so that the intake end  32  and exhaust end  34  are canted and offset as to height the same as the mounting bosses  16  and  18  so that intake end  32  and exhaust end  34  position accurately and flatly over the respective mounting bosses  16  and  18  with axes of the locating bores  38  and  40  generally coincident with axes of the threaded bores  18  and  22 , respectively. However, it is not required that axes of the locating bores  38  and  40  be coincident with the axes of the threaded bores  18  and  22 . See also FIGS. 6 a - e  which show one embodiment of the indexing link  30  from a number of different perspectives.  
         [0030]    [0030]FIG. 3 shows a pair of rocker arm stands  42  mounted to the cylinder head  10  by a pair of mounting bolts  44 , engaging the respective threaded bores  18  and  22 . In the preferred embodiment, the rocker stands  42  are identical or substantively identical to one another, and so are given the same reference numeral. Each rocker stand  42  includes a central bore  46  for accommodating the mounting bolt  44  and a pair of mounting bosses  48  for engaging and mounting opposite ends of the rocker shaft  50  in a known manner. Each rocker stand  42  has an outwardly extending locating boss  52 , which in this embodiment is downwardly extending, i.e., extending toward the engine/cylinder head. The locating bosses  52  has the same general configuration as the locating bores  38  and  40  so as to engage the respective locating bores and be prevented from rotating with respect to the indexing link  30 . See FIG. 4, which shows a bottom view of the indexing link  30  with the locating bosses  52  of the two rocker stands  42  positioned in the respective locating bores  38  and  40 . The positioning and angle of the locating bores  38  and  40  is set to provide the correct positioning of the rocker stand  42  with respect to the cylinder head  10  when everything is assembled. The tolerances between the locating bosses and respective locating bores are preferably closely set so as to prevent any substantive rotation between the rocker stands  42  and the indexing link  30 . The respective locating bosses  52  can also be positioned elsewhere on the rocker stands  42  and the placement and configuration of the indexing link modified to appropriately interconnect the two rocker stands.  
         [0031]    In the preferred embodiment, the locating boss  52  of each rocker stand  42  is thicker than the thickness of the indexing link such that the indexing link is capable of axial movement along the locating bosses and does not alter a height of the rocker stand  42  when mounted to the respective mounting boss  16  and  20 . This also allows shims to be placed under the rocker stand  42  where necessary to adjust the height of the rocker stand  42  independently of the other rocker stand and without interference from the indexing link  30 . The use of appropriately aligned asymmetrical shapes for the bores  38  and  40 , and the respective locating bosses  52  can help assure correct assembly of the roller rocker mounting mechanism to the cylinder head  10 .  
         [0032]    [0032]FIG. 5 shows the cylinder head  10  with the rocker stands  42  for a single cylinder mounted and accurately positioned by the indexing link  30 . A rocker arm  54  is mounted on each rocker stand  42 , ready to actuate its respective valve. The present invention can also be used in engines having 3, 4 or more valves per cylinder.  
         [0033]    The present invention allows each rocker stand  42  to be independently adjusted to accommodate various valve heights and desired tolerances with respect to the cylinder head and other components of the valve train while preventing unwanted rotation of the rocker stand. Each rocker stand  42  can be identical and has a compact, relatively simple configuration, reducing inventory and manufacturing costs for different and more complex rocker stands. The indexing link is a simple, inexpensive formed metal stamping. The rocker stands  42  are preferably identical or substantially identical to each other, whether for the intake or exhaust valves, and are preferably machined from steel plate or bar stock. It is also contemplated that differently configured rocker stands can also be used in certain applications and still be aligned and anti-rotationally mounted as discussed above. The present invention can be used with most OEM and aftermarket cylinder heads without additional machining of the cylinder head or time-consuming set-up and can accommodate a range of out-of-tolerance dimensions of the cylinder head without requiring further machining of components. The customer will have fewer problems and will be less likely to unjustly blame the roller rocker components for the problems. The rocker arm stands  42  and indexing link  30  can be dimensioned and configured as necessary to be used on different engines.  
         [0034]    While the embodiment shown herein ties together an adjacent intake rocker stand and exhaust rocker stand, the indexing link can be configured where appropriate to tie together adjacent intake rocker arm stands, adjacent exhaust rocker arm stands non-adjacent rocker arm stands or even more than two rocker arm stands, whether intake, exhaust or both, where the construction of the cylinder head assembly would make such a configuration more appropriate. Although only shown with respect to the valve actuating mechanism for one cylinder, the present invention can multiplied as necessary for use with the remaining cylinders of a 2, 4, 6, 8, 10, 12 cylinder engine or an engine with any other number of cylinders.  
         [0035]    It is intended that various aspects of the embodiment(s) described above can be combined in different combinations to create different embodiments. Modifications can also be made to such embodiments without departing from the scope of the invention.