Internal-combustion engines – Poppet valve operating mechanism – Tappet
Reexamination Certificate
2000-06-21
2001-07-10
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Tappet
C123S090510
Reexamination Certificate
active
06257189
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to guides for roller valve lifters for internal combustion engines to prevent rotation of the valve lifter about its axis.
2. Description of the Related Art
Valve lifters for internal combustion engines reciprocate within the engine block and through a lifter rod operate the intake and exhaust valves. The lower end of roller valve lifters includes a roller which engages a lobe upon the engine camshaft. By using a roller at the lower end of the valve lifter, friction between the lifter and camshaft is reduced providing superior engine performance. However, the lifter roller must rotate about an axis parallel to the axis of rotation of the camshaft and guide means must be used to properly maintain the orientation of the valve lifter in this respect.
Orientation of roller valve lifters to the camshaft is usually accomplished by forming a flat orientation surface on the valve lifter which is oriented to the axis of the valve lifter roller and cooperates with a guide engaging the lifter orientation surface to prevent rotation of the valve lifter about its axis. Usually, two parallel flat surfaces are defined upon each lifter located upon opposite sides of the lifter axis.
In the past, valve lifter guides for internal combustion engines to prevent valve lifter rotation have been formed of metal and include flats which correspond to the configuration of the lifter flats. The lifter reciprocates within the guide openings and the relationship between the guide openings and lifter flats prevents valve lifter rotation. The metal-to-metal contact between the valve lifters require clearances and the guides produce wear which increases the clearances between the moving parts, and excessive noise may be generated and improper cam lobe tracking can occur. Further, conventional metal valve lifter guides are relatively heavy, expensive to manufacture and assemble within the engine, and are prone to improper assembly if care is not taken.
Many of the aforementioned shortcomings of internal combustion engine valve lifter guides have been overcome by the applicants' roller valve guide shown in U.S. Pat. No. 5,088,455. The lifter guide shown in this patent is preferably formed of synthetic self-lubricating material and is inexpensive to manufacture, long wearing and easy to install. However, the valve lifter guide shown in U.S. Pat. No. 5,088,455 is of such a construction as to accommodate only certain types of internal combustion engines, and cannot readily be used with some types of V-block or straight engines.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a low cost effective anti-rotation guide for internal combustion engine valve lifters which may be readily used with V-block engines, and may readily be designed to accommodate various sizes of engines, even those in which the valve lifter bores are not centered upon a common centerline, and/or the lifters operate at differing angles relative to the engine block face.
Another object of the invention is to provide an anti-rotation valve lifter guide using a plurality of resilient fingers for engaging the valve lifter and preventing rotation thereof, the resiliency of the fingers insuring an effective engagement between the guide and the valve lifters.
Yet another object of the invention is to provide a versatile anti-rotation valve lifter guide utilizing resilient cantilever mounted fingers and wherein a valve push rod guide is mounted upon the fingers having alignment means to facilitate push rod assembly with the valve lifters.
SUMMARY OF THE INVENTION
The valve lifter guide of the invention can be formed of any material, including a polymer, stamped metal, ceramic or any material capable of being formed in the desired configuration. The guide must have a limited degree of resiliency, and from a cost and manufacturing standpoint, molding the valve lifter guide from a synthetic polymer is desirable.
The valve lifters in a V-block internal combustion engine are located within cylindrical guide bores obliquely related to the vertical. Half of the lifters are located on one side of the engine longitudinal axis, while the other half of the lifters are on the other side of the engine axis. A valve lifter guide in accord with the invention is associated with the valve lifters on both sides or banks of the engine and it is only necessary to install a single guide for association with all of the valve lifters used in a V-block engine arrangement.
The valve lifters with which the guide of the invention is used are of cylindrical configuration having a roller located at the lower end for engagement with the engine camshaft. At the upper end of the valve lifters, one or a pair of spaced parallel flat orientation surfaces are defined in diametrically opposed relationship, and one of these flat orientation surfaces is engaged by the guide along a linear line of engagement to prevent rotation of the valve lifter about its longitudinal axis. The upper end of the valve lifters are engaged by valve push rods which operate the engine's inlet and exhaust valves by a rocker arm assembly.
The valve lifter guide includes a central body of an elongated form having parallel lateral sides. The body includes engine attachment means, such as holes for receiving bolts or other mounting structure, whereby the guide may be firmly affixed to the engine block at a central location and the length of the guide body is parallel to the engine length.
A plurality of resilient cantilever supported fingers extend from each of the guide body lateral edges. These fingers are relatively stiff, but capable of limited resilient deflection relative to the body. The fingers are spaced from each other along the associated body lateral edge, and the length of adjacent fingers will normally be different in order to accommodate the location of the engaged valve lifter with which the finger is associated.
The outer end of each of the guide fingers is formed with a linear surface for engaging a flat valve lifter orientation surface. It is this linear engagement of the outer end of a finger with a valve lifter flat surface which prevents rotation of the valve lifter about its axis.
In the preferred embodiment of the invention, the finger valve lifter linear engaging surface is defined by forming the outer end of the guide fingers with a convex surface created by shaping the finger ends of a J-configuration wherein the end of the fingers extends away from the engine block. The convex surface defined by the J-configuration extends the width of the fingers defining a linear line of contact with the valve lifter flat orientation surface, and also, the length of the fingers is such that the finger ends will simultaneously engage the surface of the engine adjacent the guide bores in which the valve lifters are received. The resilient nature of the fingers permits this dual engagement of the fingers with the valve lifter and the engine block and, of course, the length of the fingers is accurately controlled during manufacture to permit this dual engagement of the finger ends.
As the convex J-configurations formed on the finger ends have a length parallel to the central valve guide body, and, in most cases, are of a width equal to the finger width, the resultant linear line of contact between the finger ends and the valve lifter flat guide surfaces effectively prevents rotation of the valve lifters.
In a variation of valve lifter guide utilizing the concepts of the invention, the ends of the fingers are formed with a flat surface which directly engages the valve lifter flat orientation surface. Additionally, aprons are defined on the end of the guide fingers extending from the fingers' flat surface whereby a valve lifter rod guide may be formed on each finger end to facilitate the assembly of valve lifter rods with the valve lifter ends. The valve lifter guides include an opening for receiving the valve lifter rods, and alignment structure, such as oblique surfaces, are defined on the rod g
Herioux Mark A.
Moretz Ralph D.
Lo Weilun
TMJ Properties, L.L.C.
Young & Basile P.C.
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