US2934051A - Rocker adjusting mechanism - Google Patents

Description

April 26, 1960 c. M. DRI-:w

ROCHER ADJUSTING MEcHANsM 3 Sheets-Sheet l Filed May 28, 1956 '51k nu F1.

INVENTOR.

TTOP/VEY April 26, 1960 c. M. DREW ROCKER ADJUSTING MECHANISM 3 Sheets-Sheet 2 Filed May 28, 1956 April 26, 1960 c. M. DREW ROCKER ADJUSTING MECHANISM 5 Sheets-Sheet 3 Filed May 28, 1956 INVENTOR. fin/gaie? Z/Zfzz/ B Y Ai Trop/vif ROCKER ADJUSTING MECHANISM Application May 23, 1956, Serial No. 587,770

Claims. (Cl. 12S-90) This invention relates generally to a valve-operating train for use in an internal combustion engine and the like which includes a valve rocker and is particularly concerned with the fulcruming of the rocker and the vregulation of clearance in such a train.

In a valve train of the type concerned with here, the valve (usually a poppet valve) has a stem portion that extends from the cylinder block. A strong spring between a flange on the stem and the block urges the valve closed 0r onto its seat. By the aid of a cam arrangement operated from the engine shaft, a push rod transmits motion to one arm of a valve rocker having a second arm which is adapted to engage the top of the valve stem and push the valve off its seat against the biasing action of the valve spring. The dilerent components of such a train are subject to temperature changes which cause their lengths to vary. For this reasonit is common to allow slight clearance between the diierent components of the train when the engine is cold and include a clearance regulator or lash adjuster which automatically regulates or adjusts this clearance so that it is zero regardless of any temperature changes and consequent variations in lengths of the components of the train. Probably the most common present form of such an adjuster or regulator is the so-called hydraulic valve lifter which is usually located in a guide in the cylinder block between the push rod and camshaft of the engine.

One of the difficulties with the use of such regulators is their location which makes them relatively inaccessible for changing out, maintenance and repair since they are located well down in the engine block below the rocker arm and the push rod. Furthermore, due to the hydraulic fluid involved in the operation of hydraulic valve lifters they include a multiplicity of parts with rather critical lits between them. Since a lash adjuster located at the rocker arm pivot is in a relatively accessible position particularly when compared to the location of usual hydraulic valve lifters, it is proposed here to combine such an adjuster with the fulcrum for the rocker arm, land in order to cut down the number of parts and also eliminate the need for critical lits between such parts, make the adjuster mechanical rather than hydraulic. In addi- `tion, by combining a mechanical clearance regulator with the rocker fulcrum or pivot, the rocking movement of the rocker may be utilized to cause the regulator to properly function in a unique manner to be hereinafter set forth. It is, then, broadly an object of this invention to pro vide a clearance regulator or lash adjuster of an improved mechanical type at the rocker fulcrum. l It is a further object of the invention to provide a combination rocker arm fulcrum and clearance regulator which is adapted to be used in combination with the new States Patent y types of stamped dish-like rockers found in present high rice For a fuller understanding of the invention and the ob jects thereof reference is made to the accompanying de ,tailed description and drawings, in which:A

Figure 1 is a transverse sectional view through a portion of `an internal combustion engine whose valve-operating train includes a rockery and the novel combined fulcrum and clearance regulator in accordance with the invention.

Figure 2 is an enlarged fragmentary view of the engine and the rocker assembly of Figure 1 showing the parts in greater detail.

Figure 3 is an enlarged fragmentary view in section taken substantially on the line 3-3 of Figure 2 to show the relationship between the threads of the members of the rocker arm fulcrum. v

Figure 3a is a fragmentary view on an enlarged scale of portions of the mating threads of Figure 3, but with the members arranged in theoretical or hypothetical position to illustrate how the threads are formed so that diametrical or lateral clearance is provided between the members which enables them to move laterally relative to each other.

Figure 4 is a fragmentary view similar to Figure 2 with parts broken away and in section showing a modified version of the invention.

Figure 5 is another fragmentary view with parts broken away and in section showing a further modification.

Figure 6 is a view taken Isubstantially on the line 6 6 of Figure 5 showing a detail of the modilication of Figure 5.

Figure 7 is another modication of the invention.

vReferring now to the drawings, in Figure l the engine is illustrated as having a cylinder blockvand crankcase 1 in which a power piston 2 operates in a cylinder 3. The numeral 4 designates the engine cylinder head in which is reciprocably mounted a poppet valve 5 biased to its closed position by a return spring 6 and movable in the opening direction by a cylinder head mounted valve rocker 7 in response to upward movement of a push rod 8 operatively connecting the push rod to ran engine-driven cam 9 through a tappet 10. As seen by the embodiment of Figure 2, the rocker 7 is stamped into a cup-shaped form with a hole 11 in the bottom thereof extending in the direction ot thrust applied to the rocker by push rod 8 and the stem of the valve 5. Pressed `in the cylinder block 1 is the lower end of a stud 12 having a shank portion extending in the direction of thrust through the opening 11 in rocker arm 7. The upper end of shank 12 is threaded as at 13 and has screwed thereon a nut 14 provided with external threads 15 adjacent its lower end. A body member 16 telescopically associated with nut 14 and shank 12 is provided at its upper end with threads 17 and is threaded on the nut 14 so that an annular chamber 18 is formed around shank 12 between the threaded portions 15 and 17 and the bottom of the member 16. Member 16 is provided at its lower end with a spherical lconvex bearing surface 19 which cooperates with a similar spherical concave bearing surface 20 in the bottom of rocker 7 to define the rocking axis of the rocker.

Turning briey to Figures 3 and 3a which represent enlarged detail showings of the threads 15, 17 of Figure 2, it will be observed that there is lateral or diametrical clearance between the threads 15 which has been indicated by the symbol C. This' lateral or diametrical clearance C allows the members 12 and 16 to slide laterally on the helical threaded surfaces so as to take up the clearance in one or another direction for a purpose which will ap- :pear shortly.

Returning to Figure 2, it may -be seen that located in the annular chamber 18 is a helical coil spring 21 through which the shank 12 extends and whose lower end 2 2 extends axially and is anchored in a suitable holel tapped inthek bottom of the member 16. The upper end 23 of spring 21 also extends axially and is anchored in the lower end of the portionof the nut 14 carrying the threads 15 an axially extending passage- 24 whose diameter; is` larger thanthat ofthe end' 23 and communicates with a passageway 25 in communication with the threaded pontionsl', 17. Innaddition to 'the lateralv or diametric C clearance provided between the threads 15, 17 there is also providedlclearanceK between the surface Vdening. the opening in the bottom of the member 16 andthe outer cylindrical surface of the shank 12. Spring -21istorsionallyloaded' so that it tends to wind the body -or member" lfdownwardl'y on the-threads 15 ofthe nut 14. Lubricating oil is supplied from an oil gallery 26 in the'4 cylinder head 4to a *passage 27 in the shank 12 leading via' a port 28 to the chamber 18. The oil may 'then pass from the chamber 1S viathe passages 24 and 25 to the ' threads 15 and 17 so as to lubri'cate these threadsand allow Ithebody 16 to turn more easily on Vthe' nut 14. This same oil alsonds its way between the surfaces 19 and 26 so as to lubricate these latter surfaces. The operation of the combined fulcrum and clearance regulator is as follows: The function of the regulator is to main-tain a small load between the parts of the valve train when the cam follower is on the base circle of the cam. As the temperature and hence the expansion of the parts in the valve train increases the loadV between the various parts of the train would increase'if the adi juster could not compensate for the expansion of the parts until the load would `become as great asthe valve spring load. Any further expansion of the parts due to further increases in temperature would prevent vthe valve from seating-an extremely undesirable condition because ofthe consequent loss of engine power as well as burning of the valves, etc. Thermal contractionof the parts ofthe train tending to cause lash in the valve-operating train would irst remove the small inertia load and any further contraction would leave slack or lash between 'the parts of the valve train. When this happens the spring '21 in the adjuster, which then has no axial load on it,

cantake over and due to the. -torsional load thereon wind the'body downwards on the threads 15 and 17 so as to take up any slack or lash. So far, the operation of the adjuster is straight forward. AThe diicult part, however, of any mechanical lash adjuster is getting Vit to go in the opposite direction or leakdown so as to take care of 'too much expansion in the parts which would otherwise retain the valveV off its seat. 'The present invention provides compensation for any such expansionA because the small diametrical clearance C allows slipping to take place in these threads at the start of the valvelift cycle until this clearance C is closed in one direction. The rest of the slipping then takes place between the .rocker 'and-'the body until full valve lift is reached. At some pointl during valve closing slipping also takes place in the thread-s 15 and 17 in the V.opposite direction. The threads 15, 17 have a helix angle so that the body will just not screw down under .direct load; however, when the aforementioned slipping is taking placel as described the Ibody will sorew down a minute amount per cam revolution. The reason for this is easier to demonstrate than to describe but depend-s on the condition that when 'a -body'is dragged across a slightly inclined plane it tends Vthat the'lateral sliding which ,takes place between Athe threads 15, V17 is caused by the rocking action of the rocker 7'which tends to cock or move the body 16 laterally in one direction or theother relative .to thenut 'I4r dependingy on the directionof rocking of the rocker 17". .'lhismovement ofthe body '1,6 Arelative to the nut 14 is, of course, Ymadepossible by the aforementioned clearfances C" and K.

It is importantto realize that' itisV the rocking action ofthe rocker 7 as it rocks under the forces exerted by the push rod 8 and the valve stem 5 which causes the sliding movement between threads 15, 17 and makes this so-called leakdown possible to compensate for expansion of the parts in the valve train which might otherwise maintain the valve off its seat.

Turning now to the modification shown by Figure 4, like numerals are used to indicate like parts in this modication and the embodiment shown in Figure 1.. In Figure 4 it will be observed that the spring 2l has its endsl 22 and 23 anchored in the body 16 and nut 14 in the same manner as the embodiment shown in'Figure 2 except that there is no direct communication of oil to the loose threads 15, 17.

Again, as the case of 'the modification of Figure 4, like parts in the modication of Figure 5 of the embodiment shown in Figure 2 are indicated by the same numerals. t will be noted, however, that in the embodiments shown in Figures 2 and 4 the spring 21 is attached to the lbody 16 and the nut 14 by inserting the ends in-to small drilled holes. It has been found that these holes are hard to drill in production. Therefore, in the modiiication of Figure 5, the body 16 and nut 14 are provided with lower and upper cup-shaped depressions 29 and 50. The diameters of these cup-shaped depressions are less than the freeoutside 4diameter of the spring 21 so that the ends of the springs are compressed inwardly. In addition, the spring 21' has a right-hand spiral so that the twist in it tends to unwind it. This also helps to insure that the ends of the spring do not slip in the cups.

Figure 6 illustrates a further detail of the modification of Figure'S which comprises a retaining cap or piece 31 which snaps into place on the upper end of the body 16 so as to limit the body 16 from screwing down too far ont-he nut 14.

Again, in Figure 7, like numerals are used to designate like parts in the embodiments `shown in Figures 2, 4 and 5. ln this embodiment the lower end' of the spring 21 is frictionally seated in an upwardly facing cup-like depression 32 in the upper end of the body 16 which is again of lesser diameter than the `free outside diameter of spring 21. rIbis spring also 4has a right-hand spiral so that the twist -in it tends to unwind it. The upper end of spring 21 has an end 33 turned in and anchored in a tapped hole 34 in the upper end of nut 14, immediately below 4the cap 35 so that the spring acts as a retainer to prevent the body 16 from screwing down too far. In

the embodiment of Figure 7 oil is supplied to the center of the threads 15, 17 viaport 28 and annular clearance 36 and port 37 at the center of threads 15, 17 for more positive lubrication. These threads have a very high thread angle and a crown on the iiank of the nut thread Vto improve slipping between these threads.

Vbeing iixed, the other of said members being arranged to have a rocker mounted thereon so as to exert rthrust thereagainst in opposition to said resilient means, the

l other4 of said members being arranged to have such rocker 'oscillate thereon about a point iixed relative thereto so that vthemotion thereof causes cocking of said members in opposite directions relativeto each other and sliding movement between said threaded portionstending toitake up said diametrical clearance in one direction or the other and thereby induces relative axial adjustment between said members.

2. In combination with a rocker having an opening extending therethrough in the thrust direction, clearance regulator supporting means for the rocker comprising a rst threaded member extending through said opening with sufficient clearance to accommodate rocking movement of said rocker, a second threaded member telescopically associated with said first member and loosely threaded thereon through which said first member extends, said rocker and said second member having co-acting spherical bearing surfaces defining the rocking axis of said rocker, resilient means acting between said members tending to unthread them, said members having lateral clearance between the associated threaded portions thereof to allow the members to cock in opposite directions relative to each other such that the rocking action of said rocker on said second member through said spherical bearing surfaces causes cooking and consequent lateral sliding between said threaded portions which induces relative axial adjustment between said members.

3. In combination with a rocker having an opening extending therethrough in the thrust direction, a clearance regulator having combined therewith supporting means for the rocker comprising a first member extending through said opening with suicient clearance to accommodate rocking movement of said rocker, said first member having an enlarged externally threaded portion thereon beyond the thrust side of said rocker, a second member telescopically associated with said first member and having an upper internally threaded portion loosely threaded on said externally threaded portion and forming an annular chamber around said iirst member between said rocker and said threaded portions, said rocker and said second member having co-acting bearing surfaces defining the rocking axis of said rocker, said first member having an oil-conducting passage extending in the direction of thrust through said rocker, said first member having a port connecting said chamber to said passage, an oil passageway in said enlarged threaded portion communicating with said threaded portions and having an axially extending leg leading from said chamber, a helical coil spring around said first member in said chamber having an axially extending end of smaller diameter than the diameter of said axially extending leg and anchored therein, the opposite end of said spring being anchored to said second member, said spring being torsionally loaded so as to tend to unthread said members, said members having lateral clearance between the threaded prtions thereof to allow the members to cock in opposite directions relative to each other such that the rocking action of said rocker on said second member causes cocking and consequent lateral sliding between said threaded portions which induces relative axial adjustment between said members.

4. In combination with a rocker having an opening extending therethrough in the thrust direction, a clearance regulator having combined therewith supporting means for the rocker comprising a first member extending through said opening with su'icient clearance to accommodate rocking movement of said rocker, said first member having an enlarged externally threaded portion thereon beyond the thrust side of said rocker, a second member telescopically associated with said first member and having an upper internally threadedl portion loosely threaded on said externally threaded portion and forming an annular chamber around said rst member between said rocker and said threaded portions, said rocker and said second member having co-acting bearing surfaces defining the rocking axis of said rocker, an upwardly facing annular spring seat in the bottom of said second member around said first member, a downwardly facing annular spring seat at the bottom of said externally threaded portion, a helical coil spring in said chamber about said rst member of greater normal diameter than said spring seats having its opposite ends frictionally engaged in said seats and torsionally loaded so as to tend to unthread said members, said members having lateral clearance between the threaded portions thereof such that the rocking action of said rocker on said second member causes sliding between said threaded portions and induces relative axial adjustment between said members.

5. In combination with a rocker having an opening extending therethrough in the thrust direction, a clearance regulator having combined therewith supporting means for the rocker comprising a first member having a shank extending through said opening with sufiicient clearance to accommodate rocking movement of said rocker, said first member having an externally threaded portion on said shank beyond the thrust side of said rocker, a second member telescopically associated with said first member and having an upper externally threaded portion loosely threaded on said externally threaded portion, said rocker and said second member having co-acting bearing surfaces defining the rocking axis of said rocker, said first member having a cap thereon above said threaded portions, the upper end of said second member forming an annular upwardly facing spring seat above said threaded portions, a helical coil spring of larger normal diameter than said annular seat having a lower end fixed therein, the upper end of said spring abutting said cap and having a laterally extending end anchored in said first member immediately below said cap, said spring being torsionally loaded so as to tend to unthread said members, said members having lateral clearance between the threaded portions thereof such that the rocking action of said rocker on said second member causes sliding between said threaded portions and induces relative axial adjustment between said members.

References Cited in the le of this patent UNITED STATES PATENTS Chayne et al. Sept. 20, 1955

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