Abstract:
A system and method for reducing or eliminating the flexing of an engine rocker shaft at high RPM conditions. In one aspect of the invention, an elongated block stud is utilized in conjunction with a rocker shaft pillar mount to more securely hold the rocker shaft in position by having all forces transmitted to a block stud which is secured to the engine block. In a second aspect of the invention, a two-piece rocker shaft center support is utilized with the lowermost piece being secured to the cylinder head by a block stud threaded into the engine block. The rocker shaft thus is secured in position along its full length between each rocker arm no matter what cylinder head configuration is encountered.

Description:
BACKGROUND AND OBJECTS OF THE INVENTION 
     This invention is generally related to the internal combustion engine arts. 
     Specifically, the principles set forth herein are applicable to engines having a lower camshaft and pushrod configuration in conjunction with an upper rocker shaft location. 
     While the invention is specifically designed for modifying a Chrysler 440 or 340 C.I. engine, it will be appreciated by those of skill in the art that the described design has wide ranging utility in the engine arts. 
     It is known in the art that high-powered engines experience a significant loss of power at high RPM levels, i.e., on the order of 6,000-9,000 RPM. It now has been discovered in the development of the present invention that such high RPM power losses appear to be caused by cylinder head vibration or flexing which, in turn, is caused by flexing of the elongated rocker arm shaft at high RPM&#39;s. The elimination of the aforementioned high RPM power loss, in accordance with the present invention, therefore, comprises a major advance in the engine arts. 
     Accordingly, it is a principal object of the present invention to eliminate rocker shaft vibration and/or flexing at all engine operating levels, including high RPM conditions. 
     It is a further object of the invention to provide means wherein the elongated rocker shaft is more securely held in its intended position as contrasted with prior art systems. 
     It is also an object to provide a dual rocker shaft support system which readily is useable along cylinder heads of varying heights. The Chrysler 440 or 340 C.I. engine has such variable cylinder head height configurations as do other engines in the art. 
     Still another very important object of the invention is to provide supports for the rocker shaft between successive rocker arms on said shaft and, moreover, while said supports, in operation, are connected by studs to the cylinder block, they may be removed from said studs without disconnecting the combustion head from its attachment to said cylinder block, thereby preventing water leaks and the like. 
     These and other objects and advantages of the present invention will be apparent to those skilled in the art from the description which follows. 
     It has been known generally in the engine arts to utilize elongated bolts for the retention of rocker arm assemblies. However, the specific and advantageous structure of the present invention has not heretofore been demonstrated in the art. 
     PRIOR ART PATENTS 
     The most closely related prior art patents currently known to be pertinent to the present invention herein described are listed as follows: 
     U.S. Pat. No. 3,200,804 - Hensler, issued Aug. 17, 1965; U.S. Pat. No. 3,584,612 - Uflacker, issued June 15, 1971; and U.S. Pat. No. 4,612,885 - Yoshikawa, issued on Sept. 3, 1986. 
     The Hensler and Uflacker patents listed above show elongated bolt usages in conjunction with multiple rocker shaft engine designs. They do not, however, teach the elongated rocker shaft retention of the present invention. Nor do they teach the specific design of the present invention which utilizes a dual rocker shaft support system to account for the varying cylinder head heights of a high performance engine. 
     The Yoshikawa patent is related to overhead cam engines and teaches elongated bolt usages for the retention of intake and exhaust cam shafts. The Yoshikawa patent is not concerned with rocker shaft flexing which now has been discovered to be an apparent cause of power loss at high engine RPM. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary plan view of a typical cylinder head and block upon which supports for the rocker shaft are secured by studs to the cylinder block. 
     FIG. 2 is a vertical sectional view of the cylinder head and block taken on the line 2--2 of FIG. 1. 
     FIG. 3 is a vertical sectional view of the cylinder head and block taken on the line 3--3 of FIG. 1. 
     FIG. 4 is a vertical sectional view of the cylinder head and block of a conventional engine not adapted for high speeds and highlighting, by contrast, the changes afforded by the present invention. 
     FIG. 5 is an enlarged perspective view of one of the supports of the present invention which is bipartite and the parts are shown in partially separated position. 
     FIG. 6 is an enlarged perspective view of another support of the present invention which is unitary. 
     FIG. 7 is an enlarged perspective view of still another support of the present invention which is unitary but narrower in one dimension than the support shown in FIG. 6. 
     FIG. 8 is a fragmentary enlarged sectional view of the rocker shaft and a stud extending therethrough with adjacent oil passages. 
     FIG. 9 is a sectional fragmentary view taken on line 9--9 of FIG. 8. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     To provide a basis for the description of the present invention and especially to contrast it with conventional engine construction which is adapted to be modified to incorporate the present invention therein, attention is directed to FIG. 4 of the drawings in which an exemplary internal combustion engine is shown of a Chrysler 440 or 340 C.I. engine. In said figure, it will be seen that a cylinder block 10 is shown fragmentarily and upon which a sectional view of a combustion head 12 is mounted. Extending upward from the upper portion of combustion head 12 is a pillar mount 14 upon which a typical conventional rocker shaft 16 is supported and a threaded bolt 18 extends through a suitable aperture in the shaft 16 for threaded engagement with a bore 20 in the pillar mount 14. 
     At least certain sections of the combustion head 12 have internal cavities 22 for purposes of receiving cooling liquid and, as shown in FIG. 4, the section shown therein is evidence of a weakened portion 24 above which the pillar mount 14 extends to support rocker shaft 16. With this condition in mind, it can be seen that especially when an engine of this type is operated at very high speeds, such as those encountered in racing cars, the relatively weak support for the rocker shaft 16 induces flexing and vibrations in the shaft and the rocker arms 62 which are mounted thereon, thereby causing loss of power and erratic operation of the engine. The present invention primarily modifies the conventional construction shown in FIG. 4 in a manner best shown in sectional views in FIGS. 2 and 3, which modified structure is adequate to eliminate such flexing and vibration of the rocker shaft 16, details of which are now to be described. 
     Referring to FIGS. 1, 2 and 3, which illustrate the essential details of the invention, particular attention is directed to FIG. 1, which comprises a fragmentary one-half of the combustion head 12 and cylinder block 10 of a V-type internal combustion engine. This figure adequately discloses the basic principles of the present invention which comprises the addition of specially designed supports for the rocker shaft 16, these supports respectively being illustrated in FIGS. 2, 3 and 5-7. It will be understood that in adapting supports for the rocker shaft 16 to various locations along the combustion head 12, the aforementioned different sizes of mounts are required in order for the same to be supported suitably upon the combustion head. 
     Referring to FIG. 2, there is illustrated therein a unitary type of support 26, which, for part of its support, rests upon a machined surface 28, which is the lower part of a pillar mount 14. A positioning stud 30, which is threaded, preferably for its full length, extends through a bore in the rocker shaft 16 and the lower end of it is threaded into a bore 32, as well as a continuation of said threaded bore into the casting 34 of the combustion head 12. The support 26 has a precise bore 36 therethrough which is very closely commensurate with the diameter of the rocker shaft 16 in order to form a precise fit therebetween. 
     Support 26 is firmly clamped against the machined surface 28 of pillar mount 14 by the use of a washer 38 and a nut 40, which is tightened against the washer and support to form part of the securing means for the latter with respect to cylinder block 10. Additional support is afforded by providing an additional bore 42 in support 26 through which an elongated threaded stud 44 extends, the stud 44 having appreciable length and extending through a bore 46 in the combustion head 12 and, finally, is threaded into a threaded bore 48 in cylinder block 10, thereby firmly clamping support 26 of the rocker shaft 16 with respect to the cylinder block 10. 
     One additional feature of the invention comprises an additional nut 50 which is threaded on stud 44 against a washer 52 which abuts a prepared machined surface 54 that is formed on the combustion head 12, said nut and washer 50 and 52 being applied before the mount 26 is placed in operative position with respect to the threaded stud 44. A further nut 56 is threaded onto the upper end of stud 44 against washer 58 and thereby firmly clamps the mount 26 with respect to the cylinder block 10. 
     Referring to FIG. 3 wherein a different form of support is employed because of its location longitudinally along the combustion head 12, as shown in FIG. 1, the support 60, which is illustrated in detail in FIGS. 3 and 5, is bipartite. Referring to FIG. 1, it will be seen that supports of this type are positioned between each pair of rocker arms 62. Because of the nature of the casting comprising cylinder block 10 where the supports 60 are located, different securing means for such supports with respect to the same being firmly connected to combustion head 12 are employed. Referring particularly to FIG. 3, it will be seen that an elongated threaded stud 64 has the lower end thereof threaded into a threaded bore 66 in cylinder block 10 and extends upward therefrom through a bore 68 formed in the lower portion of the combustion head 12 and a machined surface 70 is formed on the combustion head 12 to receive a washer 72 and a nut 74, which is threaded onto the stud 64 and, when the nut 74 is tightened, it firmly connects the combustion head 12 to the cylinder block 10 and thereby prevents any leakage of water from the cooling system, even when the support 60 is detached from the engine, as in the case of the unitary support 26, shown in FIG. 2, when it is disconnected from the engine. 
     To adapt the bipartite support 60 to the rocker shaft 16 and because of the impossibility of extending the threaded stud 64 to a distance above the rocker shaft 16, it was found necessary to form the support 60 with an upper part 76 and a lower part 78, details of which are best shown in the exploded view shown in FIG. 5. The lower half 78 of support 60 has a lateral portion 80 on the lower portion of part 78, said lateral portion having a bore 82 extending therethrough through which the threaded stud 64 extends after the nut 74 has been tightened to clamp the combustion head firmly against the cylinder block 10. A nut 84 and washer 86 then are assembled upon the upper end of the threaded stud 64, thereby firmly clamping the lower part 78 of support 60 firmly against the tightened nut 74, thereby firmly connecting the lower part 78 of support 60 relative to the cylinder block 10. 
     Upper part 76 of the support 60 is firmly clamped against lower part 78 by means of threaded bolts 88, which respectively extend through suitable bores 90, see FIG. 5, and are threaded into threaded openings 92 in lower part 78 of support 60. The upper and lower parts 76 and 78 of support 60 also respectively are provided with one-half of a cylindrical opening 104 which accommodates the rocker shaft 16 for firm support thereof stationarily with respect to combustion head 12 by means of the various clamping arrangements described hereinabove. 
     All of the supports 26, 26&#39; and 60 are formed from heat-resistant aluminum in the preferred embodiments, one example of which is 70-75 T 6 aluminum. The rocker shaft 16 preferably is formed of high carbon steel, case hardened at its outer surface. The rocker arms 62 are of a rugged nature, highly capable of transmitting the force of pushrods 94, shown in phantom in FIGS. 2 and 3, to the valve stems 96 for purposes of compressing heavy duty type valve springs 98 which are substantially stronger than conventional valve springs used in standard engines not specifically adapted for racing purposes. 
     For purposes of distinguishing the various supports with respect to each other, it is considered that the supports 26 and 26&#39; are alternate supports and the intermediate supports 60 which are of a very narrow nature, are considered to be supports between said alternate supports, thereby defining terms used in the appended claims. Further, from FIG. 1, it will be seen that support 26 is wider in an axial direction of shaft 16 then supports 26&#39;, especially in view of the fact that the rocker shaft 16 usually is of a continuous nature and since the supports 26 are between pairs of the rocker arms 62, more support for the rocker shaft at the location of supports 26 is needed than at the ends of the shafts where narrower shaft supports 26&#39; are sufficient for purposes of the invention. 
     Hereinabove, it has been indicated that the rocker shaft 16 has an axially-extending cylindrical opening 100 therein for the transmission of liquid lubricant. Particularly in the location, such as shown in FIG. 2, where threaded studs 30 extend through shaft 16, if no provisions were made for the flow of the lubricant past such studs, desired lubrication would not occur. Accordingly, the present invention includes opposite undercut passages 102 through which the lubricant bypasses the stud 30, whereby ample lubrication can be effected throughout the entire length of the rocker shaft 16. 
     From the foregoing, it will be seen that because of the effective firm anchoring of the various supports 26, 26&#39; and 60 with respect to the combustion head and firmly and indirectly to said cylinder block, another advantage is made possible. It concerns the provision of changing the location of the bore in the several types of support for the rocker arm shaft which receive and support the same. Such variation of the position of said bore in the supports, in both horizontal and vertical directions with respect to the axis of the shaft, provides the possibility of variations in the geometry of the rocker arms, as well as valve lift, timing characteristics and the like. All of this is made possible without disturbing or changing the design of the cylinder block or the combustion head and the stud means for holding the two firmly connected; only changes in the design of the support are necessary. 
     In view of the foregoing, it is apparent that a relatively simple but highly advantageous support means for the rocker arm shaft are provided in several forms or embodiments, which render the rocker arm shaft free of any appreciable or detrimental flexing or vibration, whereby full power of the engine is produced, especially when operated at relatively high racing speeds, as well as at so-called normal speeds. 
     The foregoing description illustrates preferred embodiments of the invention. However, concepts employed may, based upon such description, be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly, as well as in the specific forms shown herein.