US2457943A - Rocker arm construction - Google Patents

Description

Jan. 4, 1949. G, VINCENT I 2,457,943

ROCKER ARM CONSTRUCTION Filed Nov. 13. 1945 v 2 Sheets-Shqec 1 31 1 32 6Q INVENTOR.

fess G Z/L'ncen Jan. 4, 1949.

G. VINCENT ROCKER ARM CONSTRUCTION 2 Sheets-Sheet 2 Filed NOV. 15, 1945 4 INVL'ZNTOR. (/2556 G Z/Lnw i Patented Jan. 4, 1949 ROCKER ARM CONSTRUCTION Jesse G. Vincent, Grosse Pointe, Mich, assignor to Packard Motor Car Company, Detroit, Mich., a

corporation of Michigan Application November 13, 1945, SerialNo. 628,018

' Claims.

1 I The invention relates generally to multicylinder internal combustion engines and more particularly to a rocker arm construction therefor.

Ina Rolls-Royce engine of the type now employed in airplanes and having the cylinders arranged in a line, the rocker arms for operating the intake and exhaustvalves are located over the cylinders. The entire engine iscompactly designed, and because of such compactness the rocker arms for the intake and exhaust valves of each cylinder are nested together to occupy a minimum of space.

The rocker arms are operated by cams on a shaft extending lengthwise of and over the cyl inder head casting, and such cams are constructed to provide a fairly large throw. Each cam therefore has a steep rise. The rocker arms heretofore used have had a slidingor rubbing contact with the cams, which, with the steep rise of the cam, resulted in undue wearon the rocker arm. To eliminate such wear, aroller mounted on the rocker arm may be employed; the roller thus providing a rolling contact instead of a rubbing contact, However, in attempting to mount a suitable roller on therocker arm, difficulty is encountered because of the nested arrangement of the arms. The arm itself requires some enlargement to provide space for the roller and at the same time maintain sufiicient strength in thearm. The roller also has to be adequately supported in the arm by means such as a pin or axle, and such pin must be retained in the rocker arm in fixed relation thereto without materially increasing the overall dimensions of the arm.

The general object of the invention is therefore to provide a novel rocker arm construction provided with a cam-engaging roller supported in the arm in such a manner that the over-all dimensions of the arm are not materially increased over the dimensions of the prior rollerless arm, so that the present arm may be substituted for the prior type without altering any other portions of the engine.

More specifically, it is an object to provide a rocker arm constuction provided with a camengaging roller supported in the arm by a pin or axle which is headless so as not to project beyond the side faces of the arm and which is so secured in the arm as to be rigidly retained therein without danger of shifting or loosening during operation of the engine.

may be readily manufactured and assembled.

A further object is to provide a novel rocker arm construction provided with a cam-engaging roller carried by a pin or axle rigidly retained in the arm and providing for adequatelubrication of the bearing for theroller.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which? Figure 1 is a fragmentary view of a portion of an engine provided with rocker arms embodying the features of the invention.

Fig. 2 is an enlarged sectional view taken on the line 22 of Fig. 1.

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 1. I

Fig. 4is a sectional view taken on the line 4-4 ofFig.3, I

In Fig. l, I have illustrated a portion of an internal combustion engine of the type herein contemplated, and in this figure there is shown a cylinder head In provided with a plurality of brackets II supporting a camshaft I2 and a pair of rocker arm supporting shafts I3. The camshaft I2 is mounted directly over the ends of the cylinders, while the rocker arm supporting shafts I3 are equally spaced from and are on opposite sides of the camshaft I2, the rocker arm. shafts I3 being positioned below the camshaft l2 toprovide a triangular arrangement therewith, as is apparent in Fig. 3. Carried by the shafts I3 are a plurality of rocker arms, indicated generally at I4, the rocker arms being arranged in pairs respectively mountedon thetwo shafts I3 and extending toward each other in an overlapping relation to actuate valves in the cylinder head II], the rocker arms being operated by cams I5 provided on the camshaft I2 and overlying the rocker arms I4.

The engine herein partially shown is compactly designed to occupy a minimum of space. As an incident to such compactness, the rocker arms I4 are nested together in pairs, as is apparent from an inspection of Figs; 1 and 4; The cams I5 in an engine of this type have a fairly large throw and therefore each cam has a steep riseor ramp forming the lobe of the cam. Heretofore, rocker arms have been so constructed as to have a rubbing contact with thecams and, because of such steep rise, the rubbing action produced undue wear on the rocker arms. Much of such wear can be eliminated by providing a roller on each rocker arm to contact with the cam so that a rolling contact would thereby be substituted for the rubbin action. However, because of the nested arrangement of the rocker arms, it was difficult to mount a roller on the arm both because of the added space required for the roller and because of the problems involved in suitably supporting the roller in the rocker arm.

The present rocker. arm construction is designed to eliminate these difficulties and provide a rocker-arm construction having an adequately supported roller arrangedso that the rocker arms herein disclosed may be substituted for the rocker arms heretofore employed without making any The dowel pin 35 similarly may be subjected to operational stresses and I, therefore, provide a means for retaining the dowel pin 35 in position. To this end, the axle is provided with an internal bore 36 and within the bore I insert a retaining pin 31 extending adjacent the inner end of the portion 38 dimensioned to have a press fit within change whatsoever in the general layout of the engine. To this end, each rocker arm (see Figs. 3

mounted on the shaft l3 and extending inwardly.

from each end of the hub 2| with their inner ends spaced as at 23. nects with its hub portion 2| adjacent one end of thelatter, as is apparent in Fig. 4, and extends fromthe upper side of the hub portion 2|, as is apparentin-Fig. 3. The arm member 23 extends transversely to the shaft l3 by which it is carried and toward the opposite-shaft l3. Each arm member isthus pivotally supported on a shaft I 3 and-extends into the space between the two shafts.- At its :free end, each arm member 2!! is provided with an adjustable tappet 23 threaded therein, the tappet being provided with a ball and socket connection with a valve actuating member 25. a

, From anginspection of Fig. 4, it will be noted that the arm members 20 of adjacent rocker arms are in a nested arrangement so that they can actuate the tappets 24 which are substantially in alignment transversely of the shafts I3.

The cam I5 for each rocker arm is positioned overthe-arm and located intermediate the ends of the latter. To provide for a roller in the arm to engage thecam l-5, each arm member 20 is provided with :a pair of spaced hub portions 30 intermediate its ends and thus providing a slot'3l extending vertically through the arm member 20. Mounted within the slot 3;! is the cam-engaging roller, indicatedat 32, the diameter of the roller 3-2 being preferably slightly greater than the diameter of the hub portions 30. 1

.-;Because of the nested arrangement of the two arms of each pair, as showninFig. 4, and the proximity of the arms to the brackets H (see Fig. 1),:no space is available for an axle for the roller. which protrudes beyond the side. faces of the arm member. Any axle utilized .for the roller thus must lie within the limit of the side faces ofthe arm member, that is, within the limit of the outer faces of the two hub portions .33. For this reason, I have provided an axle 33 (see Figs. 2 and 4) supported in the hub portions 30 and extending ,through the roller 32, the axle 33 having its end faces flush with the outer faces of the two hub portions 30. The roller 32 is rotatable relative to its axle 33 and preferably is provided with aninternal bushing 34 mounted-on the-axle 33.

3 The axlev 33 'must, of course, be held in fixed relation to the'ar-m member 20 so that it cannot shift relative thereto and, to this end, the axle is dimensioned so that it :has -a press fit within the :hub portions 30. Such press fit alone would be insufficient, under the stresses to which it is subjected, to maintain the axle in proper position. Adowel pin 35 is therefore :provided, extending-radially in the axle and one of thehub portions -30 and having a .press fit in the latter.

The arm member .23 conthe bore 36 of the axle so that it will be retained therein, and a reduced inner end 40 extending adjacent the inner end of the dowel pin 35.

The press fit of the axle within the hub portions 30 as well as the press fit of the dowel pin 35 within the hub portion may, of course, be suffic-ient in certain instances to prevent any shifting of either of these members. However, as a safety factor it is desirable to utilize the retaining means in the form of the pin 3i to prevent any chance of the dowel pin 35 shifting. So long as -the dowel pin 35 remains in place, the axle 33, of course, is prevented from shifting longitudin-ally or rotatively relatively to the hub portions 30. The retaining pin 31 can never be subjected toany substantial operational stresses that might tend to dislodge it, since the only stresses that could be placed-thereon would be due to aslight shifting of the dowel pin 35. However, the slight stresses resulting from any such shifting are tranve-rse to the axis of the pin. 31 and, therefore, would have. no material tendency to cause the pin 31 to shift. Thepress fit of the portion-38 of the pin3 l thus is sufficient to retain the pin within the axle. The construction is, therefore, such that, while the dowel pin, which holds the axle against any shifting movement, is subjected to operational stresses, the retaining pin- 31 is substantially free of stresses-of this character so that the various parts of the assembly will remain in their proper relation.

The dowel ,pin 35 .-is adapted to be inserted through passages provided for supplying oil to the bearing surfaces between the roller bushing 34 and the axle 33. Thus, each shaft 13 is pro vided with an internal bore 4| connected to a source -of oil under pressure. Within each hub portion 21, the shaft '33 is provided with a radial passage42 leading to -a longitudinally extending grooved-3 in the periphery of theshaft 13. The groove 4-3 extends across the space 23 between the inner ends of the two bushings-2L Thus, oil is supplied not only to the bearing surfaces within the hub portion 2|, :but also to the space 2-3 -be tween the two bushings (2 2.

Oil is adapted to be supplied to the-bearing surfaces of thebush-ingu and axle 33 from the space 23. To this end, adrilled passage 44 extends lengthwise-of thearm member 20 and tangentially intersects the space 23. The drilled passage 44 connects with a radial passage 45 :formed in the axle 33 inalignment with the dowel pin 35. The passagesyd l and 45 are somewhat larger than the dowel pin 35 so that the latter maybe inserted through the passages 44 and 45 when assembling thedowel pin, axle and arm member. The outer end-of the passage 44 may be-closed by-a threaded pl g 46- c The-bore-36 'withintl-ie axle-33 is utilized as a portion of the toil passage and thus does .not extend all the way through the axle 33 so that it leaves a closed end 50 therein. The-other end of the bore 36 is 'closed by the enlarged portion 38 of the retaining pin 31. The reduced .end of the retaining .pin '31,.prov'ides a closed annular space within the axle 33in communication with the oil passages 45and 44. Toconnect'this annular space with the bearing surfaces of the bushing 34 and axle 33, a radial passage 5| is provided in theaxle 33 withinthe roller 32. The radial passage5l extends to a longitudinal groove 52 provided in the periphery of the axle 33 and lying within the bushing 34. Thus, the various oil passages heretofore described provide ameans for supplying oil to the roller and, at the same time, provide space for inserting the dowel pin 35in the assembly of the parts. 1

It will be noted that the axle 33 has no head portion or the like which would protrude beyond the side faces of the hub portions 30. Thus, the entire assembly lies within the confines of the arm member 20 and, because of the dowel pin 35 and retainer pin 3l, the axle will be adequately retained in its proper position. By so constructing the axle, it has a uniform diameter throughout its length. It thus may be finished on a centerless grinder, facilitating manufacture thereof.

From the foregoing description, it will be apparent that the rocker arm construction herein disclosed may be substituted for rocker arms heretofore employed without necessitating any changes whatever except those in the arm itself. The arm provides a rolling contact with the cam which eliminates wear heretofore encountered and provides a smoothly operating construction.

I claim: l l i i l 1. A rocker arm construction of the character described comprising an arm member, a camengaging roller, an axle supporting said roller and extending transversely of said arm member with the ends of the axle lying within the limits of the side faces of said member, means for holding the axle against endwise and rotational movement relative to said member and subjected to operational stresses, and axially extending means in said axle mounted substantially free of operational stresses for preventing dislodgement of said first-mentioned means.

2. A rocker arm construction of the character described comprising an arm member having axially spaced hub portions, a cam-engaging roller positioned between said hub portions, a hollow axle mounted in said hub portions and supporting said roller, said axle and one of said hub portions having a radial oil passage, a dowel pin positioned diametrically opposite said oil passage and insortable therethrough, said dowel pin holding the axle against axial and rotational movement relative to said arm membenand means mounted in said axle for holding said dowel pin against dislodgement.

3. A rocker arm construction of the character described comprising an arm member having intermediate its ends a pair of axially spaced hub portions, a cam-engaging roller positioned between said hub portions, a hollow axle mounted in said hub portions and supporting said roller, said arm member and said axle having an oil passage extending longitudinally from one end of said arm member radially through one of said hub portions and said axle, a dowel pin positioned in alignment with said oil passage and insertable therethrough, said dowel pin extending through said axle and into said one hub portion to hold the axle against axial and rotational movement relative to said arm member, and means secured in said axle for preventing dislodgement of said dowel pin.

4. A rocker arm construction of the character described comprising an arm member having intermediate its ends a pair of axially spaced hub 6 portions; a cam engaging :roller positioned be tween said hub, portions, a hollow axle mounted in said hub portions "and supporting said roller, saidaxle being closed at one end and open at the other end,said. arm member and said axle having an oil passage extending longitudinally from one end of said arm member radially through one hub portion and said axle adjacent the closed end of the latter, a dowelpin positioned in alignment with said oil passage and insertable therethrough, said dowel pin extending from the hollow interior of said axle radially outward and into said one hub portion, said axle having a second radial oil passage extending from the interior of the axle to saidfroller, and a retaining pin secured in and closingthe open end of said axle and having a reduced inner end extending adjacent said. dowel pinto prevent dislodgement thereof and providingan annular spacezwithin said axle connecting said oil passages. l

5. A rocker arm construction of the character described comprising an arm member having intermediate its ends a pair of axially spaced hub portions and an. oil passage extending from one end of said arm member into one of said hub portions,,a cam-engaging roller positioned between said hub portions, a hollow axle mounted in said hub portions to support said roller and having a pairof oil passages connecting said roller with the oil passage in the arm member through the interior of said axle, means insert! able through the oil passage in the arm and through one of said pair of oil passages for holding the axle against axial and rotational move- I ment relative to the arm member, and means secured in the interior of said axle for preventing dislodgement of said first-mentioned means and shaped to provide space connecting said pair of oil passages in the axle.

6. A rocker arm construction of the character described comprising an elongated arm member having a bearing at one end adapted to be mounted on a rock shaft provided with oil supply passages, said arm member also having intermediate its ends a pair of spaced hub portions, a cam-engaging roller positioned between said hub portions, a hollow axle mounted in said hub portions and supporting said roller, said axle having oil passages for supplying oil to said roller, a dowel pin for holding the axle against axial and rotational movement relative to said hub portions, and means secured in said axle for preventing dislodgement of said dowel pin, said arm member having a longitudinal oil passage extending tangentially from said bearing to receive oil therefrom and into one of said hub portions to connect with the oil passages in said axle, said dowel pin being insertable through said longitudinal passage.

'7. A rocker arm construction of the character described comprising an arm member having an end portion provided with a bearing adapted to be mounted on a rock shaft and having a pair of spaced hub portions with an oil passage connecting said bearing with one of said hub portions, a cam-engaging roller positioned between said hub portions, an axle carrying said roller and mounted in said hub portions and having an oil passage comprising axially and radially extending portions connecting the oil passage in the arm with said roller, means insertable through the oil passage in the arm and through a radially eX- tending portion of the passage in the axle and into said one hub portion for holding the axle against axial and rotational movement, and

1 7 means secured in the axially extending portion of the oil passage in the axle for preventing .dislodgement of said first-mentioned means.

8. A rocker arm construction of the character described comprising an arm member having a pair of spaced hub portions and an .oil passage leading to one hub portion, an axle extending from one hub portion to the other, a cam-engaging roller rotatably mounted on saidaxle between said hub portions, said axle having a lon-v gitudinally extending oil groove in its periphery underlying said roller and an oil passage connecting said groove withthe oil passage in said arm member, means insertable through the oil passagein the arm member for holding the axle against axial and rotational movement relative to the arm member, and means secured in the oil passage in the axle to prevent dislodgement of said first-mentioned means, both of said means being shaped and positioned to permitfree flow of oil through said passages to said groove.

9. A device of the character described comprising an arm member having a slot, a cam-engaging roller positioned within said slot, a hollow axle supporting said roller and extending transversely through said member with a. press fit therein and with the ends of the axle flush with the side faces of the member, a dowel pin having a press fit in said member for holding the axle against endwise and rotational movement relative to said member, and a retaining pin mounted in said axle substantially free of operational stressesfo'r insuringagainst dislodgement of said dowel pin.

10. A .device of the character described com prising an arm member having a slot, a cam-engaging .rollerpositioned within said slot, a hollow axle supporting said roller and extendingtransversely through said member with a press fit thereinand with the ends of the axle flush with the .side faces of the member, a dowel pin havin a press fit in said member for holding the axle against endwise and rotational movement relative to said member, and a retaining pin for said dowel pin mounted with a press fit in said axle, said retaining pin extending transversely to said dowel pin and being mounted in said axle so as to be substantiallyfree of operational stresses.

JESSE G, VINCENT.

REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS Wienke Mar. 12, 1946

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