US 3754539 A
Device for use with a conventional engine rocker arm of the type pivoted between its ends by a spherical wall on the rocker arm, supported by a ball support on the engine, characterized by a spring urged member engaging the spherical wall, and maintaining it in stablized engagement with the ball support.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191 Bandimere Aug. 28, I97 3 ENGINE ROCKER ARM STABILIZER 1,797,105 3/1931 ShObiOm 23190.41 x 3,045,657 7/1962 Sampleiro 123/9042 X  Invenmr- Mm Bmdimmi 3276 Bent, 3,160,148 12/1964 Giacoea et a1. 123/9041 x Denver 80212 3,289,657 12/1966 Winter, Jr 123190.41 x 22 Filed: June 29 3,335,709 8/1967 Mikucki 123/9041 1 1 pp N05 267,583 Primary Exqmigrer-Al Lawrence Smith Attorney- Sheridan, K. F. Ross et al.  CI. 123/9041, 123/9035, 74/519  1111. c1. F011 l/16, F011 1/18 [571 STRACT  Field of Search 123/9041, 90.42, Device for use with a conventional e g e oc e a m 123/9043, 90,35; 74/519 of the type pivoted between its ends by a spherical wall on the rocker arm, supported by a ball support on the  R f ren Cited engine, characterized by a spring urged member engag- UNITED STATES PATENTS ing the spherical wall, and maintaining it in stablized 1,346,401 7/1920 E1118 123/9041 engagement the ban suppm' 1,478,679 12/1923 Shaw 123/90.41 7 C, 4 Wing Figures BACKGROUND OF THE INVENTION In push rod operated valve-in-hearl or I combustion engines, such as those employed in automotive vehicles, it has long been the practice to pivotally support the rocker arms, between their ends, on a fixed rocker arm shaft. Such shaft, being cylindrical, formed a bearing support for constraining the oscillation of the arm in a plane perpendicular to the shaft axis. Adjustment of valve clearance was usually attained by an adjustable length push rod or other suitable adjustment in the valve actuating mechanism.
More recently, the rocker arms on some engines have been superseded by a construction in which each arm is provided with a spherical socket between its ends which engages a ball support secured to the engine head. The ball support is disposed on a stud affixed to the engine head which passes through an elongated slot in the rocker arm socket, whereby it may oscillate relative to the ball support and stud. In this construction, the rocker arm is not positively restrained to oscillate in a plane, as in the former rocker-shaft construction, and may universally pivot in lateral directions on the ball support along with its principal v desired oscillation in a plane. V
This lack of constraint to oscillate the rocker arm in a plane, as in the shaft supported construction referred to, produces undesired backlash take-up between certain of the parts, producing premature wear thereon. For example, if the line of contact between the valve actuating end of the rocker arm is at an angle to the plane of the end of the valve stem, such end first strikes the valve stem at a point contact and thence rolls around its longitudinal axis into line contact therewith, the ball support permitting such motion. This produces non-uniform wear between the parts, as distinguished from a constant line contact during backlash take-up as normally occurs with the former shaft supported rocker arm construction referred to. As this wear increases, the end of the valve stem wears a cavity in thesurface of the valve contacting end of the rocker arm, further destroying the optimum rolling and sliding line contact, which eventually may beat a hole through such end, completely destroying the rock arm. in addition to the deleterious action referred to, the walls of the elongated slot scufi and beat the stud, producing undesired wear on both.
Another factor which contributes to the foregoing is the lack of maintaining the optimumbacklash or clearance in the linkage between the camshaft and the actuating end of the rocker arm which, as is well known, may occur at the various points at which the linkage members contact each other. Thus, in the most simplified form of linkage, the ball support may be periodically adjusted on its supporting stud to maintain the total clearance or backlash to specified tolerances. ln a more complicated linkage, a hydraulic lifter may be employed between the camshaft and the push rod which normally maintains zero backlash as wear increases. Hydraulic lifters, however, are subject to malfunction and may not maintain zero backlash in which event backlash or clearance may be present in the linkage in the same manner as the more simplified linkage referred to.
Since the opposite ends of the ball type rocker arm are substantially the same as a shaft supported rocker arm and since the latter was not subject to the wear conditions referred to, it appears logical to attribute such wear conditions to the ball support. It also appears logical that if the ball support could provide rocker arm oscillation in a plane, as distinguished from a somewhat universal type of oscillation, it should function and wear in a manner similar to that of the shaft supported rocker arm.
SUMMARY OF THE INVENTION It has been found that the beating action and wear referred to may be minimized by applying a slight frictional force on the spherical socket which aids it in remaining in a fixed plane of oscillation. This is attained by providing a spring urged spherical cup which engages the rocker arm ball socket wall on the side opposite to that where it engages the ball support. Thus, as the rocker arm oscillates relative to the ball, the ball and socket remain in contact and excess clearance does not occur therebetween, the clearance thus being at the ends of the rocker arm where it engages the valve stem and the push rod. Moreover, since the valve spring provides the only force for oscillating the rocker arm as the valve closes, the valve stem engaging end of the rocker arm tends to remain in contact with the valve stem with the clearance occuring principally at its opposite end where the push rod engages same. This is a desirable point for the clearance, moreover, since this end is usually better lubricated than the end which engages the end of the valve stem. Thus, as the ball-shaped upper end of the push rod moves away from the correspond: ing ball socket end of the push rod, the clearance space tends to fill with oil under pressure, forming an oil cushion. On the next opening of the valve, the push rod squeezes out excess oil in the clearance cushion before rocker arm oscillationbegins, thus minimizing valve action impact, noise and wear which would otherwise occur in the absence of an oil cushion at such locus.
ln addition to stabilizing the rocker arm to oscillate in a plane, the cup forms a seal where it engages the rocker arm which, in effect, prevents excessive oil leakage around the ball support and through the elongated slot. This is attained by providing a hole in the cup which fits the ball support stud. Thus, the cup is stationary and any leakage through the elongated slot mustflow between the outer surface of the rockerarm ball socket and the spherical surface of the cup which it engages. The cup is thus lubricated with a slight oil flow and also serves as a seal to maintain an optimum oil film or cushion between the rocker arm ball socketand,
the rocker arm ball support.
In accordance with the foregoing, one of the objects of the invention is to provide a stabilizing device for use with engine rocker arms of thetype supported for oscillation about a ball and socket type pivot.
Another object is to provide a frictional resistance 0 the rocker arm to constrain it to oscillate in a plane without lateral float or movement which deviates from such plane. 7
Another object is to provide an improved oil seal be tween a spherical rocker arm socket and its associated ball support.
A Another object is to provide a construction consisting of only two parts, one being a spring and the other a punched cup, both of which may be mass produced by automatic machinery ata minimum of cost.
A further object is to provide an accessory for existing engines which may be easily installed without any alterations thereto.
Still further objects, advantages, and salient features will become more apparent from the detailed description, the appended claims, and the accompanying drawing to now be briefly described.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a central longitudinal section through a conventional rocker arm and its associated mechanism, illustrating the environment in which the subject of the invention is associated;
FIG. 2 is a section taken on line 22, FIG. 1;
FIG. 3 is an enlarged plan of a friction cup shown in FIG. 1, forming one component of the subject of the invention; and
FIG. 4 is a section taken on line 4-4, FIG. 3, illustrating a spring forming the other component of the subject of the invention.
DESCRIPTION OF PREFERRED EMBODIMENT Referring now to thedrawing, cylinder head includes valve guide 12, valve stem 14, valve spring 16 and valve spring retainer cup 18. As will be understood, the valve stem is provided with a poppet type head which seats on an annular valve seat in the head, the illustration of which has been omitted to simplify the drawing. Rocker arm 20 is provided with a wall between its ends forming an inner concave spherical surface 22 and an outer convex spherical surface 24. A stud 26 is affixed to a boss 28, such as by a press fit, and a collar 30 having a convex spherical surface 32 is slideably carried by the stud and is axially adjustable therealong by a nut 34. A conventional hollow push rod 36 operates the rocker arm by a camshaft (not shown), the push rod having a spherical end 38 which engages a corresponding socket in the rocker arm. An oil hole 40 is provided through the socket just referred to through which oil is delivered under pressure to the inner volume of the rocker arm thus flooding same and lubricating the ball socket support. Overflow oil lubricates the end of the valve stem and also the valve guide. An elongated slot 42 in the rocker arm permits the rocker arm to oscillate relative to the stud. As so far described the construction is conventional.
The subject of the invention comprises a circular cup 44 and a spring 46. Cup 44 is provided with a concave spherical surface 48 which conforms to surface 24 on the rocker arm, these surfaces being urged together by conical spring 46, one end of which abuts boss 28 and the other end of which abuts the cup. The cup is preferably provided with a circular step or shoulder 50 which engages the top convolution of the spring thereby restraining the cup and spring againstrelative radial movement. A central aperture 52 in the cup snugly but slideably fits stud 26 so that the cup remains stationary as the rocker arm oscillates relative thereto.
1. Apparatus for use with an engine of the valve-inhead type having an oscillatable valve actuating rocker arm with a pivotal portion between the ends thereof, said portion being formed by a wall of substantially uniform thickness, forming an inner concave spherical surface and an outer convex spherical surface, the inner spherical surface adapted to engage a ball support affixed to the engine by a stud, said wall also having an elongated slot extending therethrough and surrounding said stud for permitting the rocker arm to oscillate relative to the ball support and the stud, comprising;
a.'a cup-shaped member having a concave spherical surface adapted to engage said outer convex spherical surface,
b. said member having an aperture extending therethrough for surrounding said stud and engageable therewith to prevent oscillation thereof relative to the rocker arm, and
c. a spring for urging the concave spherical surface of the cup-shaped member into engagement with the outer convex spherical surface on the rocker arm, providing frictional resistance therebetween and maintaining the inner concave spherical surface on the rocker arm in engagement with the ball support.
2. Apparatus in accordance with claim 1 wherein said spring is of the conical type adapted to surround said stud and having a larger diameter convolution at one end than at the other, said cup-shaped member being circular and having a circular shoulder adjacent its periphery, said larger convolution adapted to seat on said shoulder and prevent relative radial movement between the cup-shaped member and said larger convolution, thereby retaining the cup-shaped member an spring in axial alignment.
3. Apparatus in accordance with claim 2 wherein a smaller convolution at the other end of the spring is adapted to abut the engine cylinder head at a locus adjacent where the stud projects therefrom.
4. Apparatus in accordance with claim 3 wherein said locus is a boss projecting from the engine head to which the stud is affixed.
5. Apparatus in accordance with claim 1 in combination with said rocker arm.
6. Apparatus in accordance with claim 5 in combination with a valve adapted to be opened by one end of the rocker arm and a push rod adapted to actuate the other end of the rocker arm.
7. Apparatus in accordance with claim 6 wherein the actuating end of the push rod is ball shaped and engages a corresponding socket in the rocker arm, said push rod being hollow and through which pressurized oil is delivered between its ball-shaped end and the rocker arm socket engaged thereby, producing a discrete oil cushion therebetween adapted to be partially squeezed therefrom as the push rod reduces the accumulated clearance in the system, said cup-shaped member and said spring providing a frictional force on the rocker arm tending to maintain said inner spherical surface in contact with said ball support and the valve actuating end of the rocker arm in contact with the end of a valve stem actuated thereby, whereby the principal impact on the rocker arm during clearance take-up occurs at said oil cushion, thereby reducing impact at said valve actuating end tending to wear a cavity therein.