US 3138146 A
Description (OCR text may contain errors)
June 23, 1964 R. HUTCHISON 3,138,146
MEANS AND METHOD OF LOCATING ROCKER ARMS ON A ROCKER SHAFT Filed Nov. 20, 1962 Fig, 4 (PRIOR ART) INVENTOR.
JAMES R. HUTCH ISON United States Patent The present invention relates generally to automobile engines and more particularly to a means and method of locating rocker arms on a rocker shaft.
The primary object of this invention is to provide a rocker arm assembly wherein the rocker arms are located on a rocker shaft by positively locked retm'ning means without binding or unnecessary friction, so allowing the rocker arms to operate more efiiciently, particularly at high speeds.
Another object of this invention is to provide a rocker arm assembly wherein the retaining means is adjustable to permit the use of shims to align the rocker arms precisely with their respective valves.
A further object of this invention is to provide rocker arm retaining means which is adaptable to many different engines without requiring modifications to the engines.
Finally, it is an object to provide a rocker arm assembly of the aforementioned character which is simple and convenient to install and which will give generally eflicient and durable service.
With these and other objects definitely in view, this invention consists in the novel construction, combination and arrangement of elements and portions, as will be hereinafter fully described in the specification, particularly pointed out in the claims, and illustrated in the drawing which forms a material part of this disclosure, and in which:
FIGURE 1 is a side elevation view of part of a rocker arm assembly;
FIGURE 2 is an enlarged sectional view taken on 2-2 of FIGURE 1;
FIGURE 3 is a sectional view similar to FIGURE 2, with a modified retainer; and
FIGURE 4 is a side elevational view illustrating a prior art assembly.
Similiar characters of reference indicate similar or identical elements and portions throughout the specification and throughout the views of the drawing.
Prior Art Referring first to FIGURE 4, the assembly includes a rocker shaft supported in a plurality of spaced support bearings 12 which are fixed to the'engine 14, indicated fragmentarily in broken line. The particular location of the assembly and the configuration of the support hearings will vary with different engines, but the general arrangement is somewhat standardized. On each side of each support bearing 12 are rocker arms 16 which swing freely on the rocker shaft 10 and are held against the trunnions by compression springs 18 between pairs of the rocker arms. Since rocker arms are conventionally cast and the end faces are not usually machined to any degree of smoothness, there is considerable friction between the rocker arms and trunnions on one side, and the springs on the other side. This condition is aggravated by the pressure of the springs necessary to hold Patented June 23, 1964 the rocker arms in place. At low speeds the friction can be tolerated, but at high engine speeds, as in racing cars and other high speed vehicles, the friction causes losses in performance.
Improved Structure As illustrated in FIGURES 1 and 2, a rocker shaft 20 is supported in spaced support bearings 22 and rocker arms 24 are mounted on the shaft on opposite sides of said support bearings. The rocker arms 24 each have an actuating arm 26 on one side which is engaged by the usual push rod 28, indicated in broken line in FIGURE 2, and is actuated from the camshaft, not shown. On the other side is a valve operating arm 30 which engages a spring biased valve 32, also indicated in broken line, the arrangement being well known.
To hold the rocker arms 24 in place retainers 34 are used, each retainer comprising a thin flat block with a bore 36 to fit closely over rocker shaft 20. The retainer 34, as illustrated in FIGURE 2, has an extended portion 38 split by a slot 40 extending substantially radially from bore 36. The extended portion 38 is secured together by a lock screw 49 in the manner of a split clamp, so that the retainer can be clamped securely on rocker shaft 20. The retainers 34 can be adjusted to hold rocker arms 26 in place against support bearings 22, with allowancw for small but very necessary working clearances for free operation. If necessary shims can be used, as at 44-, to position the rocker arms precisely with the ends of arms 3i) properly aligned with the respective valves 32. In the prior art assembly the use of shims increases the pressure on the rocker arm separating springs and consequently increases working friction.
Modified Structure In the configuration illustrated in FIGURE 3, the general arrangement is as described above, but a modified form of retainer is used. This retainer 4-6 has a bore 48 to fit rocker shaft 2%) and is split transversely into an upper portion 50 and a lower portion 52, which are held together by lock screws 54 on opposite sides of the shaft. Retainer 46 can thus be applied to or removed from rocker shaft 20 without the need for disassembling the shaft and rocker arms. In fact the retainers 46 can be applied to a prior art assembly without removing the springs if necessary, the springs merely being compressed to allow insertion of the retainers, which are clamped in place to hold the rocker arms. The springs are then held between locked retainers and do not cause friction on the rocker arms.
With the fully adjustable, positive locking retainers precise clearances can be set and held to allow the rocker arms to operate freely yet without undesirable play. At high engine speeds this can result in added power and wear on the parts is decreased at all speeds.
It is understood that minor variation from the form I of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and
that the specification and drawings are to be considered References Cited in the file of this patent UNITED STATES PATENTS Belden Feb. 19, 1924 Coatalen Dec. 22, 1925 Jones July 10, 1928 Vincent Dec. 4, 1928 Andres Aug. 23, 1932 Avigdor July 25, 1939 Tebaldi Dec. 2, 1941 FOREIGN PATENTS Great Britain July 30, 1931 Mal