US 3064635 A
Description (OCR text may contain errors)
Nov. 20, 1962 E. w. ROHRBACHER 3,
VALVE ROCKER MOUNTING Filed Feb. 21. 1961 INV EN TOR.
ATTO RNEY United States Patent Ofiice Patented Nov. 20, 1962 This invention relates to mounting of rockers such as used for operating poppet valves and the like in internal combustion engines, and particularly to such a mounting which promotes quiet operation and facilitates adjustment of the lost motion or lash required between the rocker operating parts to accommodate their thermal expansion during engine warm-up.
The principal object of the invention is to provide a resilient support for journaling the rocking movements of the rocker so that all such lash will be taken up when the parts of the operating system are cold, yet will accommodate thermal expansion of the parts during engine warmup to enable full return of the engine valve to its closed position at the completion of each operating cycle. The novel arrangement is particularly advantageous in providing such control of rockers of the so called stud mounted type disclosed in U.S. Reissue Patent 24,035 to Leach. Whereas the rocker therein has a fixed fulcrum axis and change in length of the valve stem and push rod during operation must be provided for as free lash when the engine is cold, or must be compensated by an automatically adjustable tappet or the like, I have so rearranged the journaling member for the rocker to be selfadjusting in the line of thrust to accomplish the desired result in a simple and economical manner. In accord ance with my invention, no self-adjusting tappet is used, and the initial adjustment of lash under cold engine conditions is made with reference to a stationary part of the engine.
The invention will be more clearly understood from the following description of a preferred embodiment thereof selected for purposes of illustration, having reference to the drawing, wherein:
FIGURE 1 is a sectional view of a portion of an internal combustion engine having the improved valve rocker mounting.
FIGURE 2 is an enlarged fragmentary view of the valve rocker mounting, with the parts sectioned and shown in their relative positions when all lash has been taken up.
FIGURE 3 is a View similar to FIGURE 2 with the parts in their relative positions prior to taking up the lash.
Referring now in detail to the drawings, there is shown in FIGURE 1 an engine cylinder block 1 in which is located a working cylinder 2 having the usual power piston 3. Closing the upper end of cylinder 2 is a cylinder head 4 in which a poppet valve 5 is slidably mounted, the latter being shown in the closed position. Suitably journaled in the cylinder block is a rotary cam 6 on which rides a reciprocable follower or tappet 7. Upward movement of the tappet is transmitted by a push rod 8 and rocker 9 to effect opening of the valve 5. A spring 10 is shown seated on the cylinder head 4 and connected to the valve to bias it to its closed position. The lubrication system of the engine may include w oil gallery 11 in the cylinder block, from which oil is conducted by a feed passage 12 to the guide bore 13 for the tappet 7. The tappet is, in turn, shown to be of hollow construction and having an external groove 14 registering with the passage 12 and connected with the interior of the tappet by a side port 15. The push rod 8 is shown to be tubular and engaging at its lower end with a centrally apertured seat 16 supported within the tappet above the port 15. The rocker 9 is shown as a sheet metal stamping, open upwardly to retain oil conducted to it from the tappet via the push rod, and the seat for the upper end of the push rod at this end of the rocker is apertured as at 17 for passage of oil thereinto. The opposite end of the rocker overlies the stem 18 of the poppet valve 5.
Intermediate its ends the rocker is provided at its fulcrum with an opening 19 extending therethrough in the line of thrust, and projecting through this opening with ample clearance to accommodate rocking movement of.
the rocker is a fixed member in the form of a stud 20 whose lower end is rigidly anchored as by a pressed fit in the cylinder head 4. Above the rocker the stud carries an abutment, shown in the form of a nut 21 adjustably threaded on the upper end of the stud. Below the nut and surrounding the opening 19 the rocker is provided with a bearing surface 22, and journaling this bearing surface during rocking movements of the rocker is an annular member 23 which is slidably supported on the stud 20. Means is also provided for resiliently biasing the journaling member 23 against the rocker, and this means in the form of a compression coil spring 24 surrounds the stud 20 and reacts against the nut 21. One or both of the nut 21 and member 23 are counterbored as indicated at 25 and 26, respectively, such that the spring 24 is enclosed thereby and when compressed to its predetermined minimum length (FIGURE 2) the nut and member 23 abut each other.
The spring 24 is selected to have suflicient stiifness that when the valve 5 is closed and the tappet 7 is in engagement with the base circle of the cam 6 (as shown in FIGURE 1) all lash between the valve, rocker, push rod and tappet is taken up. When the engine is cold the nut 21 may be adjustably positioned on the stud 20 to allow a clearance C (FIGURE 3) between it and the journaling member 23 each time the valve 5 reaches its closed position. This clearance C will be taken up at the start of each lift stroke of the cam 6, prior to opening of the valve 5. However, as the engine warms up and the overall length of the valve train increases, such increase is accommodated by compression of the spring 24. By selecting the clearance C of sufiicient value to accommodate such increase in the overall length of the valve train, complete closing of the valve 5 each time the tappet 7 returns to the base circle of the cam is assured.
Inasmuch as the spring 24 tends at all times to maintain the tappet in contact with the cam 6 and to eliminate all lash between the tappet and the valve 5, the clicking noise commonly experienced during the warmup period of engines not equipped with automatic lash adjusters is avoided. After engine starting, rapid expansion of the valve train parts occurs because the engine lubricating oil supplied from the gallery 11 passes into the tappet 7 and thence up through the push rod 8 into the rocker 9 from which the journaling member 23 and the bearing surface 22 are lubricated and the excess oil drains through the rocker opening 19 around the stud 20, warming these parts. Adjustment of the clearance C (FIGURE 3) by loosening or tightening.
the nut 21 when the engine is cold is greatly facilitated, by comparison with such adjustments conventionally made with a feeler gauge inserted between the valve stem 18 and the rocker, since the stud 20 carrying the nut 21 remains stationary during the adjustment.
While the invention has been disclosed in but a single physical embodiment for purposes of illustration, it is appreciated that various minor changes and rearrangements of the parts may be made without departing from the spirit and scope of the invention as defined in the following claims.
1. In a rocker mounting, a rocker having an opening ing surface of the rocker.
2. In a self-adjusting rocker mounting, a rocker having an opening extending therethrough in the line of thrust at the rocker fulcrum and a thrust bearing surface adjacent said. opening, a stud extending through said opening with clearance accommodating rocking movement of the rocker in operation, a nut threadedly engaging the stud opposite said thrust bearing surface, a mem- 'ber being slidable on said stud against said abutment under thrust of the rocker in operation, and a coil spring normally ber journaling said thrust bearing surface and slidably embracing the'stud between said thrust bearing surface and the nut, said member being slidable against said nut under thrust of the rockertin operation, and a coil spring interposed between said slidable member and the nut and biasing said slidable: member and the rocker axially of the stud away from said nut.
3. In a rocker mounting, a rocker, a member journaling the rocker for rocking movement, a stud slidably supporting said member for movement in response to rocker thrust, resilient means yieldably opposing rocking movement of the rocker in one direction, an abutment on the stud limiting sliding movement of the member, said memspacing said member and abutment longitudinally of the stud but yieldable to permit their engagement under the thrust imposed on the rocker in overcoming the opposition of said resilient means.
4. In a rocker mounting, a rocker having an opening extending therethrough in the line of thrust at the rocker fulcrum, a member journaling the rocker adjacent said opening for rocking movement, a stud extending through said opening and slidably supporting said member for movement therealong, resilient means opposin rocking movement of the rocker in one direction, an abutment on the stud limiting said movement of the member in the direction of rocker thrust, said member being slidable on the stud against said abutment under thrust of the rocker in operation, and a coil spring biasing the member to Ward the rocker from said abutment, said coil spring being yieldable under the thrust imposed on the member by the rocker in overcoming said resilient means.
5. The invention of claim 4, wherein one of said member and abutment surrounds said coil spring.
References Cited in'the file of this patent UNITED STATES PATENTS Re. 24, 035 Leach July 12, 1955 1,497,451 Kytlica June 10, 1924 1,699,657 Pagan Ian. 22, 1929 1,898,348 Dorer Feb. 21, 1933 2,718,219 Chayne et a1. Sept. 20, 1955 2,955,581 Fedak Oct. 11, 1960