Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1989-01-04
1989-10-10
Okonsky, David A.
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9031, 74568R, F01L 104, F01L 134
Patent
active
048724289
DESCRIPTION:
BRIEF SUMMARY
This invention relates to driving connections between two rotatable bodies having parallel but laterally-displacable axes of rotation, the first body being hollow and the second body being located within it. The invention applies particularly to connections in which the two bodies are both shafts, the first body being a hollow shaft and the second body--which is probably solid and the driving member of the combination--being located within it. The invention thus relates especially to mechanisms of the kind described in UK Patent number GB 2066361 B and European specification No. EP-A-0179581 which operate the valves of internal combustion engines, which are capable of varying the valve timing during operation to suit changes in operating conditions, and which make use of concentric rotatable shafts. UK Patent number GB 2066361 B shows a four cylinder in-line engine with the four inlet valves of the four cylinders offset relative to the four exhaust valves. This valve arrangement leaves space between the camshaft bearings of one cylinder and the corresponding bearings of the adjacent cylinder, and this space is used for the variable angular velocity mechanism which drives the short camshafts of both the cylinders. European specification No. EP-A-0179581 also describes a valve operating mechanism in which a hollow camshaft is driven by a solid shaft mounted within it, the axes of the two shafts remaining parallel at all times but being displaceable radially relative to each other. Each shaft carries a radial arm, the two arms being separated from each other in the axial direction, and one end of an axially-aligned pin is fixed to one arm. The other end of the pin engages centrally with a rectangular block which can slide up and down a radial slot formed in the second arm to accommodate relative radial movement of the axes of the two shafts.
However, present compact engine designs are now increasingly using inlet and exhaust valves which are in-line with the cylinder centres, both in engines with one inlet and one exhaust valve per cylinder and in engines with two inlet and two exhaust valves per cylinder. There is also a strong preference for the valve-operating cams to operate directly onto bucket tappets, instead of onto rockers or levers as in GB 2066361 B. Such designs leave very little space to accommodate the variable angular velocity mechanism. Similarly, the necessary axial gap (spanned by the pin) between the two radial arms in No. EP-A-0179581 requires space that can ill be afforded in a compact engine.
The present invention arises from appreciating the possibility of components of different geometry, making possible in turn a driving connection of greater axial compactness but with no less capacity for timing variation. The invention is defined by the claims, the disclosure of which is to be understood as included within the disclosure of this specification, and the invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a section through part of an internal combustion engine, taken in a plane including the axis of a camshaft;
FIG. 2 is a section through that camshaft and its associated driving member, taken in a plane at right angles to the camshaft axis, with the axes of the camshaft and its driving shaft coincident;
FIG. 3 is a similar view and shows the two cams carried by the camshaft;
FIG. 4 is similar to FIG. 2 but shows the maximum separation between the axes of the camshaft and driving shaft;
FIG. 5 is similar to part of FIG. 2 but is on a larger scale and includes further detail, and
FIG. 6 shows a modified design, viewed as if it were a section on the line VI--VI in FIG. 4.
In the sectional views of FIGS. 2-5 the customary cross-hatching of certain of the parts has been omitted, so as to avoid hiding lead lines and other detail. FIG. 1 shows an internal combustion engine including a first body in the form of a short, hollow camshaft 1, similar to those shown in UK Patent No. GB 2066361 B. Camshaft 1 carries two cams 5 and 6 whi
REFERENCES:
patent: Re31917 (1985-06-01), Mitchell
patent: 3010339 (1989-06-01), Brock
patent: 3491604 (1970-01-01), Levi
Automotive Engineering, vol. 88, No. 10, Oct. 1980, (Dallas, Tex., US), D. Scott et al: "Eccentric cam drive varies valve timing", pp. 120-124, see p. 122, lines 40-45; figures.
Lo Weilun
National Research Development Corporation
Okonsky David A.
LandOfFree
Improvements in or relating to driving connections between two r does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Improvements in or relating to driving connections between two r, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Improvements in or relating to driving connections between two r will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1950804