US20070221153A1

US20070221153A1 - High profile rocker arm assembly with offset valve lash adjuster

Info

Publication number: US20070221153A1
Application number: US11/725,814
Authority: US
Inventors: William Paul Curtis
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-21
Filing date: 2007-03-20
Publication date: 2007-09-27

Abstract

A high profile rocker arm assembly increases rocker arm strength, minimizes rocker arm weight and enables improved valve lash adjustment. The rocker arm assembly comprises a rocker arm, a cross shaft, and an externally mounted roller tip. The cross shaft incorporates certain offset structure so that when adjustment thereof is made, valve lash adjustment is quickly and easily achieved. This eliminates the need for an adjuster stud and nut on the rocker arm. Several different pillow blocks may function to operatively retain the device.

Description

PRIOR HISTORY

This non-provisional patent application claims the benefit of U.S. Provisional Patent Application No. 60/784,224, filed in the United States Patent and Trademark Office on Mar. 21, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention generally relates to a rocker arm assembly. More particularly, the present invention relates to a rocker arm assembly for enabling engine technicians to more quickly and efficiently make valve lash adjustment.
2. Description of the Prior Art
A normal maintenance item for most engines is valve adjustment. Also known as setting “valve clearance” or “valve lash,” this adjustment is an important maintenance item to insure lengthy, proper, and efficient operation of a four stroke engine. The valves in a four stroke engine open and close to allow intake air to flow into and exhaust gases to flow out of the engine. Often times a rocker/follower rides on the cam lobe (with the crankshaft and timing belt/chain turning the cams) and the rocker/follower thus actuates the valves. The cam has a “lump” for lift and a “base circle” for the duration of the engine rotation where the valve is closed. In order to insure that the valves close completely the “valve clearance” or “valve lash” is set so that there is a known clearance between the valves and the rocker arm.
The valve adjustment is important for two reasons. One, if the valves do not close properly, the engine can lose a substantial amount of power since the intake mixture will be “squeezed out” during the compression cycle (hence less mixture burned, less energy resulting from combustion). This might also result in burned valves as the exhaust valves depend partly on contact with the valve seat (head) for cooling. Second, if the valves do not open all the way, the engine will receive poor flow through the head (less mixture) and again lose power.
As the engine ages and more miles are put on it, the valve clearance can change. Repeated thermal cycling of the mechanism as well as mechanical wear will alter the adjustment slightly, resulting (typically) in increased clearance. This increase in clearance is usually characterized by an increased “ticking” at idle. Depending on the motor and the methodology, one may set this adjustment by measuring the clearance between the valve and rocker or the rocker and the cam. It will thus be understood that valve lash adjustment is required with respect to engine rocker arm systems.
Conventional stud mount rocker arm systems are economical to produce but due to the point of claiming, are too flexible and weak. Shaft mount rocker systems provide a rigid mount but with the added expense of necessary pillow blocks. More importantly, the shaft mount system adds reciprocating weight to the end of the rocker arm, reciprocating weight being the enemy of valve train lash.
U.S. Pat. No. 5,645,025 ('025 patent), which issued to Caya et al., discloses an Internal Combustion Engine. The '025 patent teaches an internal combustion engine comprising a cast cylinder head having as-cast alignment ribs that align a squared-off fulcrum in a rocker assembly. The rocker arm also has two substantially flat surfaces that engage the planar sides of the fulcrum to minimize lateral movement of the rocker arm. The fulcrum is received between the cast alignment ribs. The ribs are biased from a major axis to insure proper fulcrum alignment during assembly without the use of a jig. More particularly, the '025 patent teaches a rocker arm having a rocker body that rotates around a trunnion. The trunnion slips over a rocker stud. A nut screws onto the rocker stud to hold the rocker assembly in adjustment. This structural assembly is deficient since the clamping point or bending moment is on the bottom side of the nut, which is a distance away from the head casting.
United States Patent Application Publication No. 20050199205, authored by Curtis, discloses an Adjustable Rocker Arm Assembly for Easing Valve Lash Adjustment. The publication teaches a tubular mount system for a rocker arm which includes a rigid clamp at the base of the engine head is disclosed. Included is a pedestal mount/adjuster with external threads engageable with internal threads of a trunnion assembly cooperatively associated with a rocker arm whereby the rocker arm can be raised or lowered by turning the pedestal mount/adjuster, rotatably received by a rocker stud. This eliminates the need for an adjuster stud and nut on the rocker arm and a pillow block to hold the device together.
It will thus be seen from an inspection of the foregoing as well as other teachings commonly known in the art that the prior art does not teach a high profile adjustable rocker arm assembly comprising (1) a high profile rocker arm with sloped outer surface from the superior portion to the cross shaft-receiving bore and (2) a cross shaft comprising an offset cylindrical structure cooperatively associated with adjustment means, which when adjusted provides for valve lash adjustment. The prior art thus perceives a need for a high profile adjustable rocker arm assembly comprising (1) a high profile rocker arm with sloped outer surface from the superior portion to the cross shaft-receiving bore and (2) a cross shaft comprising an offset cylindrical structure cooperatively associated with adjustment means, which when adjusted provides for valve lash adjustment.

SUMMARY OF THE INVENTION

Disclosed is a tubular mount system for a rocker arm which provides a rigid clamp at the base of the engine head without adding an adjuster stud and nut on the rocker arm. Likewise, pillow blocks are not necessary while the device is held together with the strength of a stud. This system results in a rigid clamp without extra reciprocating weight while at the same time, providing ease of valve last adjustment.
Instead of a trunnion simply sliding over a rocker stud, the inside diameter of a trunnion or cross shaft assembly (comprising bearing means) is internally threaded to accept a tubular pedestal mount or adjustment tower (threaded externally) to threadably receive the trunnion or cross shaft assembly. Once threadably assembled, the tubular pedestal mount or adjustment tower receives the rocker stud, the assembly then being held in fixed securement adjacent the engine head by a retaining nut received by the distal end of the rocker stud. The clamping point of the adjustable rocker assembly is thus at the head casting. This structural configuration results in much more stability and durability that prior art configurations. Further, this structural assembly also allows for the valve adjustment to be made without adding an adjuster assembly to the pushrod cup of the rocker arm. This is accomplished by loosening the retaining nut and turning the pedestal mount or adjustment tower (which may be outfitted with a hex at its distal end). Since the tower is always securely clamped to the head casting, when it is turned one way or the other it raises or lowers the centerline of the rocker trunnion or cross shaft, which results in proper valve adjustment. The current invention further allows the engine builder to use different length valves and/or pushrods to change the rocker arm geometry or valve spring harmonics without machining the head or shimming the shaft assembly such as on a shaft style system.
The present invention may further comprise small oiling slots machined into the topside of the trunnions to allow oil a path to flow to the needle bearings. Oil is transferred through the pushrod and squirts out the orifice in the pushrod seat of the rocker. This oil lies on top of the trunnion. The oil slots of the present invention provide oil located in superior adjacency to the trunnion a pathway to lubricate the bearings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of my invention will become more evident from a consideration of the following brief description of my patent drawings, as follows:

FIG. 1 is a fragmentary side view of a generic internal combustion engine assembly showing a preferred embodiment of the adjustable rocker arm assembly showing a high profile rocker arm and adjustable cross shaft with portions of a pillow block assembly omitted.

FIG. 2 is a fragmentary side view of a prior art rocker arm assembly with low profile rocker arm and internally mounted roller tip.

FIG. 3 is a fragmentary side view of the rocker arm assembly of the present invention showing a high profile rocker arm and an externally mounted roller tip.

FIG. 4 is an end view of the high profile rocker arm of the present invention showing lateral sloping sides from a superior most portion thereof to a cross shaft-receiving mount thereof.

FIG. 5 is a side view of an externally mountable roller tip of the rocker arm assembly of the present invention.

FIG. 6 is an end view of the externally mountable roller tip of the rocker arm assembly of the present invention shown in FIG. 5.

FIG. 7 is an end view of the adjustable cross shaft of the rocker arm assembly of the present invention.

FIG. 8 is a longitudinal view of the adjustable cross shaft of the rocker arm assembly of the present invention.

FIG. 9 is a side view of a first alternative pillow block assembly for mounting the rocker arm assembly of the present invention to an internal combustion engine.

FIG. 10 is an end view of a first alternative pillow block assembly for mounting the rocker arm assembly of the present invention to an internal combustion engine.

FIG. 11 is a top plan view of a bottom portion of the first alternative pillow block assembly.

FIG. 12 is a top plan view of top portions portion of the first alternative pillow block assembly.

FIG. 13 is a profile view of a top portion of a second alternative pillow block assembly showing certain set screw structure for setting the cross shaft.

FIG. 14 is a cross-sectional view of the top portion of the second alternative pillow block assembly of FIG. 13 with set screw(s) omitted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, the preferred embodiment of the present invention concerns a rocker assembly for use in combination with an internal combustion engine assembly for generally improving engine performance and for enabling improved valve lash adjustment. As has been noted hereinabove, valve lash adjustment is often necessary for internal combustion engine assemblies since the most common materials utilized in the construction of internal combustion engines undergo cyclic thermal expansion and are further subject to wear. Accordingly, the valve lash or valve clearance must adjusted periodically to insure more proper function of the internal combustion engine.
The adjustable rocker arm assembly 10 of the present invention is usable in combination with an internal combustion engine assembly 11, certain generic portions of which are depicted in FIG. 1. The adjustable rocker arm assembly 10 is generally illustrated and referenced in FIGS. 1 and 2. An internal combustion engine typically comprises an engine head or cylinder head 90, a camshaft 91, a pushrod 92, and a valve 93, all as depicted and referenced in FIG. 1. As is commonly practiced, camshaft 91 is cooperatively associated with pushrod 92 for imparting motion thereto. In other words as a generic camshaft is rotated, cams integrally formed with the shaft operate to place a generic push rod into motion. It is contemplated that push rod 92 may be viewed as a generic push rod. Engine head or cylinder head 90 preferably comprises a female engine mount 94 as generally illustrated and referenced in FIG. 1.
Adjustable rocker arm assembly 10 preferably comprises a rocker arm 20 as illustrated and referenced in FIGS. 1, 3, and 4; a cross shaft assembly 30 as referenced in FIGS. 1 and 2; an externally mountable roller tip 40 as illustrated and referenced in FIGS. 1, 2, 3(a), 3(b), and 6; and a pillow block assembly 50 as illustrated and referenced in FIGS. 9 and 10. Pillow block assembly 50 preferably comprises a lower block section 51 as further illustrated and referenced in FIGS. 9-11; and at least one upper block section 52 as illustrated and referenced in FIGS. 9, 10, and 12. An alternative upper block section 53 is depicted in FIGS. 13 and 14, which block section 53 contemplates the incorporation of certain set screw means 54 for setting the cross shaft of the present invention.
Rocker arm 20 preferably comprises a rod end 21 as illustrated and referenced in FIG. 2; a valve end 22 as illustrated and referenced in FIGS. 2 and 3; and a shaft-receiving bore in which may be mounted certain bearing means 34 as illustrated and referenced in FIG. 2. The shaft-receiving bore inherently has a shaft axis 35 or rocker arm pivot axis 35 as referenced at a point in FIG. 2 (the axis extending into and out of the page). Prior art rocker arms 60 of the type generically depicted in FIG. 2 are typically designed with both strength and weight in mind.
In this regard, it is noted that the stronger the rocker arm, the heavier the weight. Conversely, the lighter the weight, the less sturdy the rocker arm. Rocker arm 20 attempts to maximize strength and minimize weight without sacrificing either desired property. In this regard, rocker arm 20 further comprises a relatively thin upper arm portion 23, a relatively thick shaft-receiving mount 24, and an outer rocker arm surface 25, which surface 25 slopes from upper arm portion 23 to mount 24 as generally depicted in FIG. 4, and as further referenced in FIG. 3. In this last regard, it is contemplated that the non-linear slope of the outer rocker arm surface may well function to localize or maximize rocker arm weight adjacent the rocker arm pivot axis for enhancing rocker arm action.
In keeping with the structural design with typical prior art rocker arms 60, it is noted that roller tips 61 are typically mounted internally relative to the valve end 62 generally due to the bulk of rocker arm 60 and particularly due to the width of valve end 62. Rocker arm 20 incorporates a relatively thin valve end 22 as a means to decrease rocker arm weight and in so doing, contemplates externally mountable roller tip 40.
Roller tip 40 is generally U-shaped as may be seen from an inspection of FIG. 6 and may be attached to valve end 22 via a pin 26, which pin 26 may also preferably comprise eccentric ends 27 (as referenced in FIG. 5) similar to that of the cross shaft 31 so that when the follower or roller tip 40 swivels, it may function to increase valve lift. The U-shaped roller tip 40 comprises opposing valve end-receiving arms as generally depicted in FIG. 6, which arms function to loosely sandwich or straddle valve end 22 therebetween for enabling roller tip swiveling type movement.
Roller tip 40 preferably comprises opposing planar valve-engaging surfaces 41 as depicted and referenced in FIG. 5, with a slight (0.272 inch) radius of curvature extending therebetween. It is contemplated that the valve-engaging surfaces and the radius of curvature are rockable upon a valve stem for enhancing valve actuation via the valve end 22.
It will be seen from an inspection of FIG. 3 that rod end 21 may preferably comprises a swiveling push rod socket 28, which socket 28 functions to receive push rod 92 via an eccentric pin 29. Eccentric pin 29 fastens push rod 92 to rocker arm 20, thereby allowing the socket to swivel eccentrically to enhance or increase the rocker arm ratio.
Cross shaft assembly 30 preferably comprises a cross shaft 31 as illustrated and referenced in FIGS. 1, 3, 7, and 8, and bearing means 34 (e.g. needle bearings). Cross shaft 31 preferably comprises a first shaft end 32 as depicted and referenced in FIGS. 7 and 8; a second shaft end 33 as depicted and referenced in FIG. 8; and a central shaft portion 35 as depicted and referenced in FIG. 8. It will be seen from a comparative inspection of the noted figures that first shaft end comprises certain adjustment-enabling structure (e.g. a male hex extension 36).
When the rocker arm assembly 20 requires valve lash adjustment, a tool (having hex-receiving structure) may be utilized to adjust cross shaft 31 by rotating cross shaft about the rocker arm pivot axis 35, markedly offset from first and second shaft ends 32 and 33. In other words, the rocker arm axis 35 is parallel to the rotatable shaft axis of cross shaft 31. This offset feature of first and second ends 32 and 33 enables valve lash adjustment requiring only slight adjusting movements, thus lessening the amount of labor involved to achieve proper valve lash.
Certain bearing lubrication means for lubricating the bearing means during operation of the internal combustion engine assembly may be further incorporated into the design of rocker arm assembly 10. In this regard, it is contemplated that the bearing lubrication means may be defined by some form of lubricant (such as oil) and lubricant-receiving slots (not specifically illustrated). The lubricant-receiving slots are preferably formed (machined) into cross shaft 31 in superior adjacency to the bearing means, thereby providing a lubricant conduit to the bearing means. The lubricant, as passed through the lubricant conduit, may thus function to lubricate the bearing means.
Push rod 92 is cooperatively associated with rod end 21 for imparting motion thereto and valve end 22 is cooperatively associated with valve 93 for imparting motion thereto. The internal combustion engine and adjustable rocker arm assembly 10 are typically constructed from thermally active, wearable materials thus requiring periodic valve lash adjustment. Thus, an adjustable rocker arm assembly for enabling valve lash adjustment is provisionally presented.
The adjustable rocker arm assembly may further be said to comprises a rocker arm, a cross shaft, a pedestal mount, and a stud assembly, the stud assembly comprising a stud and pedestal-retaining means, the stud comprising a stud axis, the stud being mounted to an engine head, the stud axis thus being fixed, the rocker arm comprising a pedestal-stud assembly-receiving gap and a shaft-receiving bore, the shaft-receiving bore having a shaft axis, the cross shaft comprising a pedestal-receiving bore, the pedestal-receiving bore comprising internal bore threads and a bore axis, the pedestal mount comprising a proximal pedestal end, a distal pedestal end, external pedestal threads, and a stud-receiving bore, the stud-receiving bore having a pedestal axis, the stud-receiving bore rotatably receiving the stud, the pedestal mount thus being adjustably mounted upon the stud, the pedestal axis thus being fixed, the proximal pedestal end engaging the engine head, the fixed stud axis and the fixed pedestal axis being collinear thus forming a fixed mount axis, the shaft-receiving bore receiving the cross shaft, the shaft axis and the bore axis being collinear thus forming a pivot axis, the rocker arm being pivotal about the pivot axis, the pedestal-receiving bore threadably receiving the pedestal mount, the cross shaft assembly and the rocker arm thus being adjustably mounted upon the pedestal mount, the pivot axis being fixed, the fixed mount axis being orthogonal to the fixed pivot axis, the pedestal-retaining means releasably securing the adjustable rocker arm assembly to the engine head, the pedestal-retaining means being operable for selectively releasing the pedestal mount for selective rotational movement, the pedestal mount thus being rotatable about the fixed mount axis for providing valve lash adjustment.
While the above description contains much specificity, this specificity should not be construed as limitations on the scope of the invention, but rather as an exemplification of the invention. Accordingly, although the invention has been described by reference to a preferred embodiment and at least one alternative embodiment, it is not intended that the novel assembly be limited thereby, but that modifications thereof are intended to be included as falling within the broad scope and spirit of the foregoing disclosure and the appended drawings.

Claims

1. A high profile rocker arm assembly, the high profile rocker arm assembly comprising a rocker arm, a cross shaft assembly, an externally mountable roller tip, and a rocker arm pivot axis, the rocker arm comprising a rod end, a valve end, a shaft-receiving bore, an upper arm portion, a shaft-receiving mount, and an outer rocker arm surface, the upper arm portion having an arm thickness, the shaft-receiving mount having a mount thickness, the arm thickness being lesser in magnitude than the mount thickness, the outer rocker arm surface sloping non-linearly intermediate the upper arm portion and the shaft-receiving mount, the roller tip being U-shaped and comprising valve end-receiving arms, the valve end being rotatably received intermediate the valve end-receiving arms, the rod end comprising a swiveling push rod socket, the cross shaft assembly comprising a cross shaft, the cross shaft comprising a first shaft end, a second shaft end, and a central shaft portion, a select shaft end comprising adjustment-enabling means, the adjustment-enabling means for rotatably enabling valve lash adjustment via the cross shaft, the adjustment-enabling means having an offset axis of rotation, the offset axis of rotation being parallel to and offset from the rocker arm axis, the offset shaft axis for easing valve lash adjustment.

2. The high profile rocker arm assembly of claim 1 wherein the roller tip comprises opposing planar valve-engaging surfaces and a radius of curvature, the radius of curvature extending intermediate the valve-engaging surfaces, the valve-engaging surfaces and the radius of curvature being rockable upon a valve stem for enhancing valve action via the valve end.

3. The high profile rocker arm assembly of claim 2 wherein a pin having eccentric ends rotatably attaches the valve end-receiving arms to the valve end, said eccentric ends for increasing valve lift.

4. The high profile rocker arm assembly of claim 1 wherein an eccentric pin fastens a push rod to the push rod socket, the eccentric pin for enhancing swivel action of the push rod socket, the enhanced swivel action for increasing rocker arm ratio.

5. The high profile rocker arm assembly of claim 1 comprising bearing lubrication means and bearing means, the bearing lubrication means for lubricating the bearing means.

6. A high profile rocker arm assembly, the high profile rocker arm assembly comprising a rocker arm, a cross shaft assembly, and a rocker arm pivot axis, the rocker arm comprises a rod end, a valve end, a shaft-receiving bore, an upper arm portion, a shaft-receiving mount, and an outer rocker arm surface, the upper arm portion having an arm thickness, the shaft-receiving mount having a mount thickness, the arm thickness being lesser in magnitude than the mount thickness and the outer rocker arm surface having a non-linear slope intermediate the upper arm portion and the shaft-receiving mount, the non-linear slope for localizing rocker arm weight adjacent the rocker arm pivot axis and enhancing rocker arm action.

7. The high profile rocker arm assembly of claim 6 comprising an externally mountable roller tip, the roller tip being U-shaped and comprising valve end-sandwiching arms, the valve end being rotatably received intermediate the valve end-receiving arms, the roller tip for enhancing valve action via the valve end.

8. The high profile rocker arm assembly of claim 7 wherein the roller tip comprises opposing planar valve-engaging surfaces and a radius of curvature, the radius of curvature extending intermediate the valve-engaging surfaces, the valve-engaging surfaces and the radius of curvature being rockable upon a valve stem for enhancing valve actuation via the valve end.

9. The high profile rocker arm assembly of claim 7 wherein a pin having eccentric ends rotatably attaches the valve end-receiving arms to the valve end, said eccentric ends for increasing valve lift.

10. The high profile rocker arm assembly of claim 6 wherein the rod end comprises a swiveling push rod socket, the swiveling push rod socket for increasing rocker arm ratio.

11. The high profile rocker arm assembly of claim 10 wherein an eccentric pin fastens a push rod to the push rod socket, the eccentric pin for enhancing swivel action of the push rod socket, the enhanced swivel action for increasing rocker arm ratio.

12. The high profile rocker arm assembly of claim 6 wherein cross shaft assembly comprising a cross shaft, the cross shaft comprising a first shaft end, a second shaft end, and a central shaft portion, a select shaft end comprising adjustment-enabling means, the adjustment-enabling means for rotatably enabling valve lash adjustment via the cross shaft, the adjustment-enabling means having an offset axis of rotation, the offset axis of rotation being offset from the rocker arm axis, the offset axis of rotation for easing valve lash adjustment.

13. The high profile rocker arm assembly of claim 6 comprising bearing lubrication means and bearing means, the bearing lubrication means for lubricating the bearing means.

14. A high profile rocker arm assembly, the high profile rocker arm assembly comprising a rocker arm and a rocker arm pivot axis, the rocker arm comprising a rod end, a valve end, an upper arm portion, a shaft-receiving mount, and an outer rocker arm surface, the upper arm portion having an arm thickness, the shaft-receiving mount having a mount thickness, the arm thickness having varied thickness relative to the mount thickness, the varied thickness for localizing rocker arm weight adjacent the rocker arm pivot axis.

15. The high profile rocker arm assembly of claim 14 wherein the outer rocker arm surface slopes intermediate the upper arm portion and the shaft-receiving mount.

16. The high profile rocker arm assembly of claim 15 wherein the outer rocker arm surface slopes non-linearly intermediate the upper arm portion and the shaft-receiving mount.

17. The high profile rocker arm assembly of claim 14 comprising an externally mountable roller tip, the roller tip being U-shaped and comprising valve end-sandwiching arms, the valve end being rotatably received intermediate the valve end-receiving arms.

18. The high profile rocker arm assembly of claim 14 wherein the rod end comprises a swiveling push rod socket, the swiveling push rod socket for increasing rocker arm ratio.

19. The high profile rocker arm assembly of claim 14 comprising a cross shaft assembly, the cross shaft assembly comprising a cross shaft, the cross shaft comprising an eccentric end, the eccentric shaft-adjusting end, the shaft-adjusting end having an offset axis of rotation, the offset axis of rotation being offset from the rocker arm axis, the offset axis of rotation for easing valve lash adjustment.

20. The high profile rocker arm assembly of claim 14 comprising means for enabling eccentric pivot action, said means for enhancing rocker arm action.