BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of an engine cylinder head including a shaft mounting device according to the present invention.
FIG. 2 is an elevational view of a portion of the cylinder head shown in FIG. 1, taken along the line 2-2 of FIG. 1.
FIG. 3 is a section view taken along the line 3-3 of FIG. 2.
FIG. 4 is a perspective view of the present shaft mounting device, in this case a camshaft cap, showing the underside of cap 22.
FIG. 5 illustrates a prior art camshaft cap.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIG. 1, cylinder head 10 has camshaft 14, which is maintained in contact with cylinder head 10 by means of a plurality of inventive shaft mounting devices, which are embodied as camshaft caps 22. As fully described below, oil needed for the operation of camshaft 14 is presented to mounting devices 22 by means of lubricant supply passages formed in cylinder head 10.
FIGS. 2 and 3 show a lubricant supply passage, 54, which is formed in cylinder head 10. Lubrication flowing up through passage 54 enters lubricant inlet port 58, which is formed in camshaft cap 22. It is noted that cap 22 has a mounting base, 30, which allows cap 22 to be securely attached to cylinder head 10 by means of screws 38. Cap 22 has a cap-shaped bearing body, 26, with a semi-circular bore, 50, formed therein. Bore 50 cooperates with bore 52 formed in cylinder head 10 to define a bearing surface for encircling a portion of camshaft 14. The portion of camshaft 14 which is encircled by camshaft retainer 22 includes two radially extending bores 46, which allow oil introduced to shaft mounting device 22 from lubricant supply passage 54 to eventually enter camshaft 14, and then to proceed along the length of longitudinal bore 42 (FIG. 3) which is formed in camshaft 14.
The elegance and simplicity of the present invention are fully displayed in FIG. 2, wherein hydraulic obstruction 66 is illustrated. Because the entirety of shaft mounting device 22, including hydraulic obstruction 66, as well as lubricant distribution channel 62, are formed in place during casting or sintering of device 22, the risks and expense of machining are eliminated. In that regard, it is well to note that machining risk includes the problem of under-machining passages, which may cause unwanted flow restriction.
In essence, hydraulic obstruction 66 functions as a weir, or flow regulator, extending partially into the upstream end of lubricant distribution channel 62. Hydraulic obstruction 66 is also shown in FIG. 4. It is easily seen from FIGS. 2 and 4 that the height and length of hydraulic obstruction 66 may be easily decreased during engine development work, so as to tune the flow of lubricant fluid passing from lubricant inlet port 58 to lubricant distribution channel 62. Note also that the adjustment of the size of hydraulic obstruction 66 during engine development may be accomplished with the use of simple grinding tools; unlike the situation with the prior art restrictor shown in FIG. 5, it is often not necessary to re-machine a separate oil restrictor, which must be then carefully cleaned of chips.
The problems encountered in manufacturing the prior art restrictor of FIG. 5 in large quantities are difficult to understate, given that the drillings required to manufacture the restrictor result in contamination, which, if not carefully removed during the manufacturing process, may cause subsequent damage, if not failure, of the very bearings which lubricant is meant to protect. This issue also arises with prior art bearing caps having machined oil distribution channels. As noted above, this difficulty is not an issue with the present inventive solution, which provides oil restriction in a robust, cost-effective manner.
Those skilled in the art will appreciate in view of this disclosure that the present shaft mounting device could be constructed from diecast metals, or sintered metal powders. Alternatively, various other materials, such as composite metallic and non-metallic materials could be employed.
While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.