Anti-rotation guide for a roller follower valve lifter

An anti-rotation guide for preventing rotation of a roller follower valve lifter in an internal combustion engine. The guide has an outer surface for engaging an engine bore and an inner surface for slidably receiving the lifter. One end of the guide includes an anti-rotation feature for cooperating with a mating feature on the lifter, preferably flats although other configurations are contemplated within the scope of the invention. The anti-rotation feature may take any of a plurality of shapes, including but not limited to an arm and tang, a flap, and an orifice flat. The guide is installed from an opening in the engine bore proximate a camshaft disposed in the engine block. The cooperating features prevent axial rotation of a lifter within the sleeve but do not inhibit axial or reciprocal motion of the lifter.

TECHNICAL FIELD

The present invention relates to internal combustion engines; more particularly, to devices for preventing axial rotation of valve lifters; and most particularly, to a sleeved anti-rotation guide which prevents rotation of a roller follower valve lifter in an internal combustion engine.

BACKGROUND OF THE INVENTION

Hydraulic valve lifters and solid valve lifters, for use in internal combustion engines, are well known in the engine art. A valve lifter of this type, engaging a camshaft lobe at one end and a push-rod or valve stem at the other end, slides reciprocally in a bore of the engine block. The lifter, typically assembled from the top side of the engine block, engages a camshaft lobe via a camshaft follower end which preferably includes a roller. Unless suitably constrained by an anti-rotation guide, a roller follower lifter may rotate axially in its bore during reciprocation, thereby undesirably misaligning its roller follower from the associated cam lobe.

Lifter anti-rotation guides in the prior art are positioned on and secured to the top side surface of the engine block adjacent the lifter bore. When fastened to the engine block above the lifter, a closely-fitting aperture in the anti-rotation guide snuggly surrounds an end of the lifter exposed above the engine block opposite the roller follower end. A locating feature in the guide aperture, such as a flat or a keyway, mates with a similar feature in the lifter to prevent the lifter from rotating about its longitudinal axis during reciprocation. Since the prior art anti-rotation guide resides above the block and occupies significant space, it may interfere with other engine components such as the cylinder head and intake manifold. Typically, a lifter is installed into its bore from the top side of the engine, and the anti-rotation guide is attached to the engine following lifter installation.

However, in some engines where the camshaft is embedded deeply inside the engine block, it is not possible for the lifters to be assembled from the top side of the block, and it may even be undesirable for an end of the lifter to be exposed above the block to be gripped by an anti-rotation guide installed on the top of the block as in the prior art. In such engines, the lifters must be installed from the bottom side of an engine block. Because of space constraints on the bottom side of an engine block, a conventional, externally mounted anti-rotation aperture guide cannot be readily adapted for use on the bottom side of the block.

Therefore, what is needed in the art is a compact anti-rotation guide that fits inside an engine block as a non-rotatable sleeve between a lifter body and a lifter bore.

What is further needed in the art is a compact anti-rotation guide that can be assembled into an engine from the bottom side, or camshaft side, of an engine block.

What is further needed in the art is a compact anti-rotation guide that can be assembled into an engine block before the corresponding valve lifter is installed.

What is still further needed in the art is a compact anti-rotation guide that also permits oil to flow to a lash-control element of a hydraulic valve lifter.

What is still further needed in the art is a compact anti-rotation guide-element comprising a plurality of individual anti-rotation guides, the element being kittable in a pre-assembly step.

It is a principal object of the present invention to provide lifter anti-rotation means that permits installation of a valve lifter from the bottom side of an engine block.

SUMMARY OF THE INVENTION

The present invention provides an anti-rotation guide for either a hydraulic or non-hydraulic roller follower valve lifter for an internal combustion engine. The guide is prevented from rotation within an engine bore by being press-fitted or otherwise constrained.

Briefly described, a guide in accordance with the invention is a generally cylindrical element having a tubular sleeve portion with an outer surface for engaging an engine bore and an inner surface for slidably receiving a valve lifter. One end of the guide includes an anti-rotation feature for cooperating with a mating feature on the lifter. The mating features are preferably flats, although other configurations are contemplated within the scope of the invention. The cooperating features prevent axial rotation of a lifter within the sleeve but do not inhibit axial or reciprocal motion of the lifter. The anti-rotation feature may take any of a plurality of shapes, including but not limited to an arm and tang, a flap, and an orifice flat.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate a plurality of preferred embodiments of the invention, in a plurality of forms; however, such exemplifications are not to be construed as limiting the scope of the invention in any manner.

Referring toFIG. 1, there is shown a roller valve lifter assembly10of the present invention. Roller valve lifter assembly10includes roller valve lifter12, and anti-rotation guide30. Roller valve lifter12includes roller14, lifter body16, and seat18. Seat18may receive a pushrod28as shown inFIG. 1or alternatively and directly a valve stem27(without rocker arm assembly29) in known fashion. Anti-rotation guide30includes generally cylindrical sleeve portion32, outer surface34, inside surface36, first end38and second end40. Second end40includes an anti-rotation feature42which will be described in more detail below. Preferably, anti-rotation guide30is formed of metal or plastic and may be machined, molded or cast in known fashion.

Diameter (D) of outer surface34is selected to be press fitted into lifter bore26of engine block25from opening31of bore26. Optionally, (D) may be selected to allow a slip fit between sleeve portion32and bore26. If a slip fit relationship is selected, a means for preventing rotation of the guide in the bore, such as for example a key and keyway, must be provided. An alternative for preventing guide rotation in bore26is discussed below. Diameter (d) of inside surface36of guide30is selected to receive roller valve lifter12slip-fittedly, to permit body16of lifter12to reciprocate freely within the guide in an axial direction. As shown inFIG. 1, when roller valve lifter assembly10is assembled into bore26, anti-rotation guide30serves as an axial sleeve between lifter12and bore26to guide the axial reciprocation of, and prevent rotation of, lifter12within engine block25.

Still referring toFIG. 1, in operation, roller14rides on a cam lobe20of camshaft22of internal combustion engine24and is displaced thereby. Roller14translates the rotary motion of the camshaft22to axial reciprocal motion of lifter body16. The reciprocation of roller valve lifter12opens and closes valve23, through push-rod28, rocker arm29, and valve stem27, as is known in the art. The outer surface of lifter body16adjacent anti-rotation feature42includes an anti-rotation feature17for mating with feature42. Feature17is preferably one or more flats; however, other configurations capable of cooperating with sleeve feature42to prevent rotation of the lifter within the sleeve are fully comprehended by the scope of the invention.

The axial length of guide30, as shown inFIG. 1, may cause the anti-rotation feature42of the sleeve to extend above the surface of the engine block. In a currently-preferred embodiment, the length of guide30is selected such that anti-rotation feature42is contained within the length of block bore26, although the relative length of guide30is not limited within the scope of the invention.

Referring toFIGS. 2 and 3, guide30amay be conveniently provided in a ganged element70wherein a plurality of guides are formed conjointly for use with an equal number of lifters.

An advantage of element70, comprising in this currently-preferred embodiment two guides30a,is that the two guides may be injection molded together from a heat-and oil-resistant plastic and mounted to engine24via a single bolt (not shown) through bolt hole72in connecting web73. Hole72may be elongate, as shown inFIG. 4, to facilitate bolting of the guide to the engine block.

Another advantage is that two-guide element70also permits two appropriate lifters to be pre-assembled as a kit and then installed simultaneously into engine24.

Still another advantage is that, when two or more guides are ganged in this fashion, only a slip fit between sleeve portion32and bore26is needed since intermediate web73prevents rotation of the guides in their respective bores.

Still another advantage is that element70assures proper initial and continuing orientation of each lifter assembly10, and especially its roller14, with respect to its cam lobe20.

Referring toFIG. 4, in a second embodiment30bof an anti-rotation guide, anti-rotation feature42aincludes flaps53extending axially from second end40. When lifter12is assembled into the anti-rotation guide, at least one flat surface54is aligned with at least one flat17of lifter body16.

Still referring toFIG. 4, in a third embodiment30cof an anti-rotation guide, anti-rotation feature42bincludes orifice64disposed in second end40and opposing orifice flats66. When lifter12is assembled into the anti-rotation guide, opposing flats66are aligned with flats17of lifter body16. (For convenience in presentation, embodiments30band30care shown together in a single element70a,although in practice the element would likely comprise one or the other but not both.)

Referring toFIGS. 5 through 8, various views are shown of an individual anti-rotation guide30b,such as has already been shown in ganged form inFIG. 4, and the parts are so indicated.FIG. 5is an axial cross-sectional view, andFIG. 6is a similar axial cross-sectional view taken orthogonally to the view shown inFIG. 5.FIG. 7is a plan view of guide30b,andFIG. 8is a bottom view thereof. Note that guide inner surface36is preferably chamfered51at first end38to facilitate entry of lifter12into guide30during engine assembly.

Optionally, roller valve lifter12may include a hydraulic lash adjuster member (not shown). As is well known in the art, a means for communicating oil from an engine oil gallery to the hydraulic lash adjuster member is needed such as, for example, an oil feed orifice through the wall of body16of lifter12. Referring to FIGS.1,5,6, oil aperture48in sleeve portion32of guide30communicates oil from engine oil gallery50to the lash adjuster. The size of aperture30can be easily and selectively formed in sleeve32in order to accurately regulate the oil transferred to the lash adjuster member.