Valve mechanism for internal combustion engine

Details Valve mechanism for internal combustion engine Valve mechanism for internal combustion engine

2000-07-25

2001-04-03

McMahon, Marguerite (Department: 3747)

Internal-combustion engines

Particular piston and enclosing cylinder construction

Cylinder head

Reexamination Certificate

active

06209507

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a valve mechanism for an internal combustion engine and, more particularly, to an improved cylinder head and valve actuating system for an overhead camshaft internal combustion engine.
It is well recognized that the performance of internal combustion engines can be improved through the use of overhead valves operated by overhead mounted camshafts. When an overhead camshaft arrangement is employed, the cylinder head assembly trends to become much more complicated than with a conventional pushrod operated engine. This is because the cylinder head must, in addition to supporting the valves and the valve springs, provide support for the camshaft and for the actuators for the valves. Frequently, the valves are directly operated and this means that an arrangement must be provided for slidably supporting the thimble tappets that operate the individual valves from the camshaft.
If all of these functions are performed primarily by the cylinder head, then the cylinder head casting becomes extremely complicated. In addition, since it is necessary to machine the bearings for the camshaft provided by the cylinder head, and the bores for slidably supporting the tappets, than machining operations also add significantly to the cost of the cylinder head. Furthermore, there is the problem of assembly of all of components into such a unitary cylinder head assembly, and the problems of accessibility the various fasteners for securing the cylinder head to the cylinder block and the bearing caps to the cylinder head for journaling the camshaft. Of course, the problems mentioned above are complicated when the engine employs twin overhead camshafts.
It has been proposed, therefore, to employ a construction wherein the main cylinder head member itself does not have to perform all of these functions. For example, in U.S. Pat. No. 4,612,885, entitle Camshaft Bearing Arrangement For Overhead Cam Engine, issued Sep. 23, 1986, in the name of Masaaki Yoshikawa, and assigned to the assignee hereof, there is depicted a cylinder head arrangement wherein the main cylinder head assembly only supports the poppet valves for their movement and the return springs for the poppet valves. The camshafts and valve actuating tappets are supported in a separate cam carrier that is affixed to the cylinder head and thus can be machined and cast separately simplifying the aforenoted problems. However, with the arrangement shown in that Patent, the cam carrier forms the outer periphery of the cylinder head and the cam cover must sealingly engage it. In addition, the cam carrier must have a sealing arrangement around its outer periphery with the upper surface of the cylinder head to afford sealing. Hence, substantial addition machining operations are required.
It is, therefore, a principal object of this invention to provide an improved cylinder head assembly for an overhead camshaft internal combustion engine.
It is a further object of this invention to provide an improved cylinder head assembly for an overhead cam internal combustion engine wherein at least some of the valve actuating tappets and at least one of the camshafts are supported by a separate cam carrier member that is affixed to the cylinder head but in such a way that this cam carrier member need perform no sealing functions for the overall cylinder head assembly.
It is a further object of this invention to provide an improved and simplified cylinder head assembly for an internal combustion engine having an overhead camshaft wherein machining and assembly operations are considerably simplified.
In addition to the problems already noted, it is also desirable to ensure that the cam actuating tappets and camshafts are well lubricated. When a separate cam carrier member is provided, this can present additional difficulties in insuring that the camshafts are adequately lubricated as are the valve actuating tappets.
It is, therefore, a still further object of this invention to provide an improved cylinder head assembly including an improved arrangement for lubricating camshaft journals thereof.
SUMMARY OF THE INVENTION
A first feature of this invention is adapted to be embodied in a cylinder head assembly for an overhead camshaft engine that comprises a main cylinder head member which defines a lower sealing surface for sealing engagement with a cylinder block. At least one portion of the lower surface cooperating with a cylinder bore of the cylinder block to define a combustion chamber. The main cylinder head member further has an upper peripheral surface that surrounds a cam chamber and which is adapted to be sealingly engaged with a cam cover for enclosing the cam chamber. A cam and tappet carrier member is affixed to the main cylinder head member within the cam chamber. The cam and tappet carrier member defines at least one bearing surface for journaling a camshaft and at least one tappet bore for receiving at least one tappet actuated by the camshaft for operating a valve supported by the main cylinder head member.
Another feature of the invention is adapted to be embodied in an arrangement of the type described in the preceding paragraph. In accordance with this feature of the invention, the cam and tappet carrier member is formed with an oil gallery that extends along its length and which is served by an oil passage that extends through a lower surface of the cam and tappet carrier member for cooperating with an oil gallery formed in the cylinder head.


REFERENCES:
patent: 4612885 (1986-09-01), Yoshikawa
patent: 4637356 (1987-01-01), Kuroda
patent: 4637357 (1987-01-01), Ohmi
patent: 4785773 (1988-11-01), Schreiber et al.
patent: 4823747 (1989-04-01), Wagner et al.
patent: 5080057 (1992-01-01), Batzill et al.
patent: 5150675 (1992-09-01), Murata
patent: 5207197 (1993-05-01), Klingmann et al.
patent: 5213071 (1993-05-01), Iwata et al.

Affiliated with

Also associated with

Rating

Valve mechanism for internal combustion engine does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Valve mechanism for internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Valve mechanism for internal combustion engine will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2493566