Machine element or mechanism – Elements – Cams
Patent
1988-05-23
1990-01-23
Smith, Gary L.
Machine element or mechanism
Elements
Cams
74567, 74838, 474400, F16H 5304
Patent
active
048950459
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION OF INVENTION
This invention is directly, but not exclusively, concerned with the ability to vary the phase, or relative timing, of the inlet and exhaust valves of an internal combustion engine, and, more particularly, with providing means for realising timing variations in respect of single camshaft engines.
BACKGROUND OF THE INVENTION
The benefits of being able to effect such a variation when instigated according to engine speed and load etc., are torque increase, and emission reduction. Furthermore, fuel economy can be drammatically improved over the whole revolution range without power output penalties.
Variable valve timing has been proposed for some considerable time. However, the majority of the solutions proposed are quite complicated and usually require a twin-camshaft engine in order to be effective. The variable abilities rely upon the availability of separate camshafts for the inlet and exhaust valves. This means that by varying one (or both) shaft(s) relative to the other, an advance/retard situation can be realised thereby changing the overlap between the valve cycles and offering a wider "optimum" timing regime.
SUMMARY OF THE INVENTION
The present invention offers these abilities to twin camshaft layouts, but also, and more importantly, provides a means of realising timing variations in respect of single camshaft engines.
The present invention can be applied to single cylinder engines and those employing two or more cylinders. Furthermore, the invention can be used in conjunction with pumping and compressor devices or the like. The present invention can also be used (as herein described) with standard types of cam devices, or in conjunction with annular cams, shafts and followers, wherein the annular cams and/or the followers can be differentiated in the same way as intended for the standard external cams etc.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be more readily understood, embodiments thereof will now be described with reference to the accompanying drawings in which:
FIG. 1 shows an arrangement embodying the principles of the invention;
FIG. 2 shows a second embodiment of the invention;
FIG. 3 is a section on the line III--III of FIG. 2;
FIG. 4 is an end elevation of FIG. 3;
FIG. 5 is a further application of the principles embodying the invention;
FIG. 6 shows the principles of the inention applied to a differential camshaft having 3 cams per cylinder;
FIG. 7 shows the principles of the invention applied to an eight valve camshaft unit;
FIG. 8 shows an embodiment of the invention using cam action to replace a differential carrier;
FIG. 9 is a plan view of FIG. 8;
FIG. 10 is a view on the line Y/Y of FIG. 9;
FIG. 11 is a view on the line W/W of FIG. 10.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to the Figures, FIG. 1 shows two dams 9, 10, bearing located upon a camshaft 1 in free-running communication. It is assumed that the cams 9, 10 are able to rotate upon camshaft 1 but are restricted from all lateral movement.
A set of bevelled differential gearing a/b/c/d is provided between the two cams 9, 10 with the idler-bevels c, d mounted in free-running bearing location upon stub-axles 3, 4 and retained thereon by end-plates 7, 8. C and d are engaged with bevelled-gears a and b with gear a being fixed to, or part of cam sleeve-shaft 5 and bevelled-gear b being fixed to, or part of cam sleeve-shaft 6.
Cam 9 is fixed to, or part of, sleeve-shaft 5 and cam 10 is fixed to, or part of, sleeve-shaft 6.
It is assumed that shaft 1 is driven by way of a sprocket for example, in the usual way. However, any other suitable drive means could be used. The differential hub 2, being fixed to, or part of, camshaft 1, will, therefore, also be driven.
If the cam assembly 9/5/a were "locked" to shaft 1, then the whole assembly 1/2/3/4/5/6/7/8/9/10/a/b/c/d would rotate en masse. Therefore, if means were provided, whereby the assembly 9/5/a could be rotated relative to shaft 1, preferably in a controlled fashion, then the resultant differential action cr
REFERENCES:
patent: 1611063 (1926-12-01), Peiler
patent: 3633555 (1972-01-01), Raggi
patent: 4522085 (1985-06-01), Kane
LONRHO PLC
Saether F.
Smith Gary L.
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