US2943612A - Valve gear - Google Patents

Description

July 5 1960 A. a; MIDDLER VALVE GEAR Filed Feb. 21, 1958 INVENTOR. A? 5 25/001. 5e BY e 41/ gg/awi U iedsme P t e VALVE GEAR Alexander G. Middler, Detroit, Mich., assignor to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Feb. 21, 1958, Ser. No. 716,584

3 Claims. (Cl. 123-90) This invention is concerned with an internal combustion engine valve gear and is especially concerned with a new and improved rocker pivot construction for inclusion in the valve train of overhead valve engines to provide a valve system in which friction is minimized. This invention is an improvement over that invention disclosed and claimed in United States Letters Patent No. 1,497,451 which issued on June 10, 1924.

An object of this invention is to provide a simply constructed rocker arm which utilizes a true rocking motion in place of the conventional pivot motion. In the past, rocker arms have generally been of the type which oscillated about a fixed pivot point. Assemblies of this construction are prevalent throughout the art.

The satisfactory operation of the usual rocker arm and the controlled oil consumption of the overhead valve engine depends considerably upon the tolerances existing between the rocker arm and the sleeve upon which it oscillates and the provision of an accurate supply of oil. The instant invention utilizes a rolling action as opposed to the sliding friction used in the prior art. The rocker underlies a fixed support and is positioned upon the support by projections on the rocker which engage projection receiving depressions in the support. The support requires little or no machining except for the projection receiving depressions as compared with the high surface finish which was required in the conventional sliding friction rocker arm shaft. The applicants improved rocker arm construction is capable of easy manufacture at a considerable reduction in cost to conventional rocker arms.

Another object of this invention is to provide a rocker arm which minimizes push rod whipping and holds to a minimum the scrubbing action of the rocker on the valve stem foot. Because of the rolling action of the rocker arm against the support, the rocker arm is moved laterally as it rocks so that both the push rod and the valve stem travel in a generally axial direction which avoids the relative whipping motion inherent in the push rods used in conventional sliding friction pivot rocker arms.

Still a further object of this invention is to provide a rocker arm movable about a support in a rolling motion wherein the closing and opening of the valve will be done at a slower rate when the valve is being seated or unseated thereby preventing pounding and battering of the valve seat due to the momentum of the valve. The change in velocity is permitted by a change in the lever arm length between the rocker arm push rod receiving portion and the cent-er of oscillation and the poppet valve actuating portion as the rocker arm moves about the surface of the fixed support.

Other objects and advantages of this invention will be made more apparent as this description proceeds, particularly when considered in connection with the accompanying drawings, wherein:

Figure 1 is a side elevation partly in section of a rocker arm and pivot construction incorporating. th applicants invention;

Figure 2 is a cross section taken on Figure 1;

Figure 3 is a side elevation view of a modification of Figure l, and

Figure 4 is a cross section taken on line 44. of Figure 3. V

Referring now to the drawings, and in particular Figures 1 and 2, the rocker arm is generally indicated at 10 and may be of the stamped, cast, brazed, or other wise fabricated design preferably of a channel shape. A convex bearing surface 11 is provided at one end of the rocker for contact with the valve stem (not shown) and a concave bearing surface 12 is provided at the opposite end for receiving the valve push rod (not shown). It is, of course, possible to change the surface to provide for an adjustable rocker arm bolt in event that fixed steel tappets are used. The depending sides 13. and 14 straddle the concave and convex bearing portions of the rocker to support the load on the rocker. The sides are joined by a web portion 15 which is in rolling contact with the fixed support. The web portion 15 in the area of the contact with the fixed support 23 is formed in the shape of an involute curve. Secured to each of the sides 13 and 14 are positioning tabs 16 which have a formed projection 17 extending above the uppermost portion of the rocker. A contact surface 18 is provided on each side of the projection 17.

The rocker 10 contacts the underside of fixed support 23. A pair of aligned projection receiving depressions 21, having mating surfaces 22 for engagement with the projection contact surfaces 18 is provided on the underside of the support. In the rocking motion of the rocker, the contact is between the underside of the fixed support 23 and the web 15 of the rocker guided in its rolling movement by the projection 17 and its surfaces 18 contacting the respective surfaces 22 of the support 23.

In Figures 3 and 4 a modified form of the construction is provided in the formation of the guide tab and projection and in its projection receiving depression in the fixed support. The rocker 24 is of a similar construction to the one shown in Figures 1 and 2 and has the convex bearing surface 26, concave bearing surface 27, and depending sides 28 and 29 joined by web 30. Instead of the projection tab 16 secured to the sides 13 and 14 as shown in Figures 1 and 2, the projection 31. is stamped from the sides 28 and 29 and is bent upwardly to project above the uppermost portion of the rocker arm. It is, of course, possible to stamp the projection 31 from the web portion 30 as well. Projection 31 is also provided with surfaces 32 on each side and is guided in the projection receiving depression 34- against mating surfaces 36 in channel shaped support 33. It is also to be noted that the web 30 takes the involute form in the area where contact is made with the fixed support 33.

In this type of construction where a rolling motion is utilized, there is no need for a positive supply of lubricant. Insofar as the projection tabs 17 and 31 are concerned, in their respective sliding movement in their respective projection receiving depressions 21 and 34, adequate lubrication is available in the form of oil vapors within the engine.

Although the embodiment disclosed shows the projection on the rocker and the projection receiving depression in the fixed support, it is contemplated and possible that the reverse may be utilized and that the projection may be placed on the support and the projection receiving depression in the rocker web. It is also contemplated that only one projection may be used instead of the two projections shown in the drawings.

It will be understood that the invention is not to be line 22 of ,Pjatented, July 5,

a q 3 limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined in the appended claims. a

What is claimed is:

, .1. Juan internal combustionengine, a stationary support, a rocker arm, said rocker arm having a web portion and a pair of. side portionsdepending from said web portion, said web portion having its upperside in rolling contact with the underside of said stationary support, said rocker arm having at least one guiding projection extending upwardly beyondthe web portion, said stationarysupport having at least one guiding projection receiving depression in the underside to receive said guiding projection, one of said stationary supports and said rocker arm web portions having an arcuate form in the area of contact between saidstationary support and said rocker arm web portionwhereby said rocker arm web portion rolls on the surface of said stationary support in a path determined by the movement of said guiding projection.

2. An improved rocker arm pivot support arrangement comprising a cylindrical support, a rocker arm underlying said support in abutting relationship, said rocker arm having a web portion and a pair of side portions depending from said web portion, said web portion having its upper side in rolling contact with the underside of said stationary cylindrical support, a positioning projection secured to each of said depending side portions and extending upwardly beyond said web portion, a positioning projection receiving depression in the underside of said stationary cylindrical support to receive each of said projections whereby said rocker arm rolls on the surface of the cylindrical support in a path determined by the movement of said guiding projections inside said guiding projection depressions.

3. In an overhead valve mechanism in an internal combustion engine, a rocker arm for actuating a poppet valve, said rocker arm having a web portion and a pair of side portions integral with and depending from said web portion, a fixed channel shaped support overlying and abutting said rocker arm, said rocker arm web portion having'an arcuate form in the area of contact between said support and said rocker arm web portion, a pair of positioning projections extending from said side portions vertically upwardly to project above the uppermost portion of the rocker arm web portion, a pair of positioning projection receiving depressions in the underside of said fixed support for receiving said projections whereby said rocker arm portion rolls on the surface of the fixed channel support in a manner determined by the movement of said guiding projections inside said guiding projection receiving depressions.

References Cited in the file of this patent UNITED STATES PATENTS 1,497,451 Kytlica June 10, 1924 1,605,722 Harper Nov. 2, 1926 1,699,658 Fagan Jan. 22, 1929 2,572,968 Bachle Oct. 30, 1951

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