US2678641A

US2678641A - Adjustable cam follower

Info

Publication number: US2678641A
Application number: US146771A
Authority: US
Inventors: Ryder Elmer
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-02-28
Filing date: 1950-02-28
Publication date: 1954-05-18
Anticipated expiration: 1971-05-18

Description

May 18, 1954. E, RYDER 2,678,641

ADJUSTABLE CAM FOLLOWER Filed Feb. 28, 1950 Elmer? Ryde/9 Z/M HIE/5 Patented May 18, 1954 UNITED STA-l 12 Claims.

The present invention relates to improvements in mechanism for controlling the operation of cam actuated valves such as valves of thepoppettype used in internal combustion engines and the like.

It has heretofore been proposed to control the operation of internal combustion engine poppet valves by providing actuating cams of varying size or height to act selectively upon the valves for determining the duration of opening or closing of the valves. One of the principal problems encountered has been that in the transition from one cam area to another, the follower means of the valve and the cam have encountered or been subjected to an inefficient degree of friction and resistance to movement, detrimental. not only to the efficient operation of the mechanism, but also subjecting the interengaging relatively frictionally movable elements to undue wear and resultant rapid breakdown in proper operating relationf ships.

An important object of the present invention is to provide improved means for controlling camactuated valves and which is substantially free from frictional losses and wear by reason of affording smooth and easy transition from and between various selective actuating cam areas.

Another object of the invention is to provide a steerable valve-controlling cam follower device.

A further obiect of the invention is to provide an improved valve-controlling cam and adjust-r able follower combination.

Still another object of the invention is to provide improved means for controlling the operation of an internal combustion engine, or other piston and cylinder apparatus in which it is de-.

sirable to control the admission of fluid to the cylinder or exhaust fluid from the cylinder lor the degree of compression to be created within the cylinder by the piston. l

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments taken in conjunction with the accompanying drawings in which:

Figure 1 is a fragmentary, more or less schematic vertical sectional view through a portion of an internal combustion engine showing mechanism embodying the features of the present invention in use therein;

Figure 2 is a fragmental horizontal sectional detail view taken substantially on the line lI-II of Figure l;

f Figure 3 is a fragmentary vertical sectional detail view taken substantially on the line IIl---III-fy OfFigureLand E se Figure 4 is a more or less schematic vertical sectional view through a modied form of internal combustion engine embodying the features f the present invention.

As shown on the drawings:

By way of illustration, having reference to Figures 1, 2 and 3, the invention is shown as embodied in a more or less conventional internal combustion engine l@ including a water cooled block i i and having therein a cylinder I2 within which is operable reciprocably a piston I3. A water-jacketed cylinder head ill closes the cylinder l2 and affords a combustion chamber l5 thereabove. An intake port il into the combustion chamber l5 is controlled by a poppet valve i8 having an axial stem IS slidably reciprocable in a bearing guide 20 and normally maintained under yielding closing pressure by a coiled biasing compression spring 2 i. At its lower end the valve stern ES engages with a tappet 22.

Opening of the valve i8 enables a fuel charge from a manifold 23 to enter the combustion chamber i5 through the inlet l1 and after closing of the valve I8 compression of the fuel is effected by the piston i3 and the fuel is then exploded by a spark created by a spark plug 24 for driving the piston i3.

According to the present invention, the interval of opening of the valve i8 is controlled selectively and preferably throughout a uniform range of. selective increments for effecting economy at various speeds of operation of, or operating de. mands upon the engine. In this manner the. volume of the fuel charge drawn into the combustion chamber i5 and the cylinder l2 is regulated for economy and eiiiciency in operation throughout substantially the entire range of operating demands. To this end, the lower end portion of the tappet 22 which extends down into the chamber dei-ined by a lower crank case portion 2e of the engine block is formed with an enlarged foot 2'! having a broad lower face 28. Below the tappet foot 27 is a rotary cam shaft 29 carrying a cam 3Q upon which rides a cam iollower 3i interposed between the tappet foot 2l and the cam 3%. As the cam shaft 29 rotates inr the direction indicated by the directional arrow in Figure 1, the lobe of the cam periodically raises the follower Si and thereby the tappet 22 and the valve H3 in opposition to the biasing spring 2i in proper timed sequence coordinated with operation of the piston i3.

In order to control the interval of opening of the valve i8, the lobe of the cam 3b is of vary-- l ing Width throughout a substantial extent longi' tudinally of the cam shaft29, the cam being for this purpose of elongated form and longitudinally centered with respect to the axis of the tappet 22. Thus, one end of the lobe 3G is quite narrow so that when the follower 3| rides this narrow end of the cam the interval of opening of the valve |8 will be short. From the narrow end the cam gradually widens toward a substantial width at the opposite end, as best seen in Figures 1 and 2. Therefore, by'moving the follower 3i lengthwise of the actuating cam 3|), the interval of opening of the valve i8 can be controlled by gradual increments from a short interval to a rather long interval.

To accomplish movement of thel follower 3| longitudinally of the actuating cam 30, afollower actuating shaft 32 is provided to which the follower 3| is connected, the shaft'32 being mounted in parallel spaced relation to the cam shaft 29 inl appropriate bearings 33 in the crank case 25. Any suitable means may be provided for reciprocably moving the follower shaft 32, shown in Figure 2 as comprising an actuating lever mechanism 32a. Biasing means suchas a compression spring 34 may be provided to act upon the shaft 32 normally to urge it toward a given position, as for example, the position in which the follower 3i is disposed midway the ends of the valve actuating cam 30'.

In a convenient and practical form, the follower 3| comprises an arm 35 provided at one end with a follower head 37 which is transversely elongated to provide a platform upon which the tappet foot face 23 bears. The length of the head 31 is so related to the width of the tappet foot 21 that proper operating Contact between the tappet foot and the follower head will prevail throughout the range of control movement of the follower longitudinally of the valve actuating cam 30. Furthermore, since in the rotation of the cam 3G with the cam shaft 213, the follower 3l must move with a roclnng movement relative to the tappet foot 2l, the upper bearing surface of the follower head 3l is preferably formed convexly transversely of the head so as to maintain adequate contact with the central portion of the tappet foot face 28 in all relative positions.

of the tappet foot and the follower.

Friction between the valve actuating cam 3|] and the follower 3| is minimized in operation by equipping the follower with a roller 33. For this purpose the lower portion of the follower head 3l has a pair of spaced, downwardly extending journal ears 39 withinwhich trunnions `40 of the roller 38 are journaled. Thus, as the cam 36 rotates, the roller 33 rides thereon smoothly and substantially without friction.

Although relative rotation of the valve actuating cam 30 and the follower roller 38 proceeds substantially without friction, relative movement inlaxial directions of the cam and roller is highly resisted by the friction of the interengaging surfaces thereof. Accordingly, means are provided for steering the follower roller 38 into various positionsof adjustment longitudinally of the cam 30 by operation of the follower shifting shaft 32. Such means herein comprise a yoke 4E at the end of the follower arm 35 opposite the follower head 3l having substantially universal connection with the shifter shaft 32 through a collar 42 `rotatably engaged about the shaft 32 and having trunnions i3 rotatably journaled in the arms of the yoke 3|. The sleeve 42 is held against relative axial movement on the shaft 32 while permitting free rotary movement on the shaft by respective stop collars lill secured xedly on the shaft at the opposite ends of the sleeve. Through this arrangement, the follower arm 35 can rock relative to the shaft 32; and in the axial movement of the shaft 32 for shifting the follower 3| longitudinally of the valve actuating cam 30, the follower arm 35 can swing toward either respective side depending upon the direction of shifting of the shifter shaft, so that follower roller 38 is steered to ride by smooth transition and substantially without frictional resistance into the desired shifted or adjusted position on the cam 30. Swinging of the follower is indicated. by the dot dash and by the dot outline positions thereof seen in Figure 2 which show, re-

f. spectively, the positions of the follower at the beginning of shifting of the follower from positions toward opposite ends of the actuating cam 30 tothe median full line position illustrated. Thus, as the cam 33 rotates, within only a very few revolutions thereof, the follower will attain the adjusted positionto which it is steered by actuation of the shifter shaft 32.

In order to assist the steering action of the follower 3| and more particularly the smooth transitional movement of the roller 38 over the cam 30 in the shifting of the follower from `place to place longitudinally of the varying width lobe area' of the cam 33, the engagement periphery of the roller 38 is preferably convex in crosssection as best seen in Figure 3. Furthermore, the varying width peak of the lobe of the cam 39 is preferably convexly formed both transversely and longitudinally. Thereby, irrespective of the angular relationship of the cam 3|] and the roller 38 during operation, friction or resistance to relative rolling movement is eliminated in a practical sense irrespective of the contacting pressures involved due to spring loadings, mass dispositions, operating speeds and the like during operation; During operation, of course, due to the universal joint connection of the follower arm 35 with the shifter shaft 32. the follower arm will normally tend automatically to assume an unbiased position relative to the shifter shaft by reason of the reaction of `the surface of the cam 3U and the contacting surface of the roller 38 in the same manner that a freely swivelling wheel on a vehicle normally assumes a straight front to rear position when in relative travelling movement over .a surface. adjustment of the position of the follower roller 38 longitudinally of the lo-be of the cam 3|) shifting movement of the shifter shaft 32 effectingy angular' deviationin the desired direction from the free normal running relationship of the follower. causes the` follower to be steered into the desired adjusted position as it automatically assumes the free, unbiased running relationship of the roller 38 over the cam 30. It will be` appreciated, of course, that the respective convexities of the contacting surfaces of the cam lobe 30 and the follower rollerV 38 enhance the tendency of` they follower to move into any steered adjusted position relative to the cam. 1

Inasmuch as unsteered relative axial movement of the cam 30 and the follower roller 38 is'frictionally resisted to a very high degree, advantage can be taken of this fact to limit the rate of control transition or shifting of the follower 3|. This is especially desirable in an internal combustion engine for smoothness and uniformity of operation. To this end means are provided for limiting the swing of the follower arm 35 relative to the. shifter shaft or rod v32. To this end the follower arm 35 i's provided with Hence, in effecting.

5. stop means comprising a pair of lateral lugs 45 located at the sides of the bight of the yoke 4| and arranged to respectively engage with the adjacent ends of the swivel or universal sleeve 42 to delmit swinging movements of the follower arm. While for some purposes it may be desirable to permit a full range of swinging movement of the follower arm in both opposite directions as limited by the lugs 45, it may be best under certain circumstances, or in certain engines, or under certain operating conditions of any particular type of engine with which the device is used to further limit or restrict the range of swinging movement in either or both directions, or to effect a differential swinging of the follower arm in opposite directions. For this purpose, stop screws 41 may be provided which are threaded through the respective lugs 45 with their tips projectable beyond the sleeve-opposing faces of the lugs to any desired adjusted extent.

In order to retain the follower 3| and more especially the roller 33 against riding off of the opposite ends of the cam 30 at the extremes of position adjustment of the follower, stop means such as lugs 48 are preferably provided and which may comprise integral or attached mem-'bers properly located on the adjacent wall of the engine block defining or providing the crank case 25. As best seen in Figures 1 and 2, the stop lugs 48 are located adjacent to the opposite ends of the cam 3U for engagement by the follower arm 35. There is also, of course, a limit upon the respective opposite shifting movements of the shifter rod, or shaft 32, which can be accomplished in any preferred fashion, but in the pres "i ent instance results from the particular spacing between the journal lugs 33, or between the journal lug 33 nearest the end wall of the crank case and a bearing boss 33a provided for the rod or shaft 32 in said end wall.

Any possibility of slap between the follower 3| and the cam 35i during high speed operation is avoided by the provision of biasing means for holding the follower against the cam 39. Such biasing means comprises a coiled tension spring 49 hooked through an ear 50 on the underside of the follower arm 35. At its opposite, or lower end, the spring 49 is hooked onto the end of a link 5| which is pivotally secured at its lower end to the adjacent wall of the crank case 25 as for example, to a boss 52 provided for this purpose. The total length of the spring 49 and the pivoted link 5| is such as to enable ample accommodation of the biasing structure to the full range of shifting adjustment of the follower 3| and to avoid undue resistance to such shifting. By preference, the biasing spring and link are lo. cated to assume a directly vertical position when the follower 3| is at mid-point of adjustment range and which may be the optimum operating relationship of the engine controls for peak normal running eiiiciency of the engine. By having the biasing spring 49 and the link 5| thus centered, the biasing effect thereof will, in addition to the normal hold-down bias also tend to return the follower 3| normally toward the central operating position relative to the cam 39 following shifting of the follower in either direction from the central position.

In the modification shown in Figure 4 the steered valve control follower is shown as applied to an internal combustion engine employing over, head valves. In such an engine a water jacketed engine block 55 has one or more cylinders 51 within which are reciprocably operable respec- 6. tive pistons 58. A water jacketed cylinder head* 59 carries one or more poppet valves 60 controllingrespective ports 6|, in the instance shown comprising a fuel inlet port 6|. A coil spring 62 normally urges the valve 60 to closed relation. A rocker arm 63 has one end portion thereof in engagement with the end of the valve stem while the opposite end of the rocker arm carries a universal joint ball 64 engaging within a universal socket 65 of a transmission rod B1 which extends down into a crank case 68 wherein is appropriately located a cam shaft 69 havingy thereon a cam 'lo identical with the previously described cam 3|). A follower 1| operates between the cam 'lo and the transmission rod 61 in the same manner as the follower 3| and embodies the same structural and operating characteristics as the follower 3| except for the slight modification required for adapting the same for overhead valve control, In order to adapt the follower 1| for cooperation with the transmission rod 61, a head 12 :ls` provided formed with an upwardly-opening, rounded, concave socket 13 within which the rounded lower end of the transmission rod 61' bears. A roller 14 carried by the lower portion of the head 12 rides the cam 10. A follower arm i5 is attached by a universal swivel connection 'I1 identical with the swivel connection for the follower arm 35, to a shifter shaft or rod 18.' Stoplug means 19 may be provided on the arm l5, corresponding to the stop lug means 45. Likewise, end limit stop lugs 89 may be provided on the inside of the crank case 68. A hold-down and centering biasing spring 8| and a pivoting connecting link 82 for the follower 15 may also be provided. Operation of the follower 1I is the same as the follower 3|, and the universal connections of the transmission rod 61 with the rocker arm 63 and with the follower head 12 enables the transmission rod to accommodate itself to all shifted and shifting movements of the follower.

While the valve control of the present invention has been specifically illustrated in conjunction with forms of internal combustion engines, since in this field a wide range of usefulness is inherent, it should be understood that the valve. Y

control mechanism would also iind use in such apparatus as compressors, and in other apparatus where reciprocable, or poppet-type valves are used and in which the interval of valve opening is desirably variable for improved efliciency under various operating conditions and demands..

While for specific illustration, intake or inlet control has been described, it will be appreciatedl that exhaust control is equally within the con-- templation and scope of the present invention. In the same apparatus, both intake and exhaust valve control can be effected by the use of sepa-A rate control mechanisms according to the present invention.

It will be understood that modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

l. Valve control mechanism comprising .a rotary cam having an axially elongated lobe of gradually increasing width from one end to the other end of the lobe, a follower member comprising an arm pivotal about an axis substantially parallel to said cam and having a roller riding the cam and a surface vabove the roller for engagement by a valve actuating member,

ashaftiupon whichsaidarmis mountedmeans.

for. axially movingsaid shaft for shifting'the' followerarm, and means providing a swivel conn'ection between said shaft andsaid arm for steerably. swinging the arm to change the position of' the` roller axially of the cam.

i 2. Valve control mechanism comprising arotarycam having an axially elongated lobeof gradually increasing width from one end to the. other endof the lobe, a follower member comprising an 'armnhaving a roller riding the cam and a surface above and adjacent to the roller for engagement by a reciprocable valve actuating member, means for shifting the follower arm, means providing a swivel connection between saidishifting means and said. arm for steerably swinging the arm to change the positionof: the rolleiuaxiaily of the cam,.and means for limiting the:swinging` range of said arm;

3. Valve control mechanism comprising a rotary Acam having an axially elongated lobeof gradually increasing width fromtonel end tothe other: end of theV lobe, a follower member comprising `an arm mounted for pivotal movement about an axis parallel to said cam and having a roller riding the camand'an enlarged arcuate surface above the roller for engagement by a valve 'actuating member, means for shiftlngthe follower arm', means providing a swivel connectionibetweensaid shifting means and saidarm for `st-eerably swinging the arm to change" the position of the roller axiallyof the cam', and means. comprising spaced stop abutments located' adjacent to the respective ends ofI the rotary cam for limiting the' range of shifting movement of the'lfollower arm with respect.' to the ends of the cam lobe.

4,'In' combination in mechanism for controlling the operation of a reciprocable valve', a follower arm'havlng at one end a roller for riding upon a camhaving a lobe of progressively varying width and a portion above said roller for engagement by valve actuating means to be reciprocated' inthe riding of the roller over the cam during rotation of 'the cam, a shifter rod reciprocably mounted on an axis parallel to the axis of rotation ofthe cam, a yoke on said arm, a `swivel sleeve on said rod and having' a uni- -versall swivel connection with said yoke, and means-for selectivelyshifting the rod to change the angular attitude of the follower arm relative to therod and thereby steer the follower roller into selected' adjusted position relative tothe cam lobe.

5. In combination in mechanism for controlling-the operation of a reciprocable valve,a' follower arm having at one end a'roller forl riding upon a cam `having a lobe of progressively varyingfwidth and a portion above said roller' for engagement by valve actuating means to' be reciprocate'd in the riding of the roller overA theV cam during rotation of the cam, a shifter rod reclproeably mounted on anaxis parallel to the axis of rotation of the cam, a yoke on said arm, a'swivel sleeve on said rod and having a universal swivel connection with said yoke, and means for selectively shifting the rod to change the angular attitude ofthe follower arm relative to the rod and thereby steer the follower roller into selected adjusted position relative to the cam lobe, said arm having stop lug 'means adjacent to the bight of said yoke' and engageable with said sleeve to limit the range ofi angular attitude or swinging movementof the arm'with respect tothe shifter rod.

6. In. combination in mechanism for controlling,` the operation of a valve, valve actuating meansincluding a follower having a roller for riding upon a cam having a lobe of substantial length and progressively varying width, means comprising a member pivotally connected to said follower on a pivotal axis transverse to the axis of thecam for steering movement of said follower by: swinging aboutsaid pivotal axis into selected positionswith respect to said lobe throughout theflength of the lobe, and means for normally yieldably maintaining the follower in a central position relative to the length of the cam lobe.

7. Incombination in mechanism for controlling-the operation of a valve, valve actuating means including a follower having a roller for riding upon a cam having a lobe of substantial length vand progressively varying width, means comprising a member pivotally connected to said follower on a pivotal axis transverse to the axis or the cam for steering movement of said follower by swingingv about said pivotal axis into selected positions with respect to said lobe throughout thev length of the lobe, and means for normally yieldably maintaining `the follower in a central position relative to the length of the cam lobe, said means comprising a tension spring and a link pivoted on a xed pivot centered with respect to the cam lobe.

8. In combination in valve controlling mechanism,.a cam follower arm having a head including: means for engagement by a valve actuatin'g member and a roller for riding upon a rotary cam having a lobe of varying effective area, said arm being pivotally'mounted onan axially shiftable. shaft having an axis substantiallyparallel to said cam for steering movement longitudinally ofthe cam while riding on said cam and during movement of said arm when shifted by said shaft, and a springL acting on said' arm to urge said roller into positive'engagement' with the cam.

9. In combination in mechanism for controlling the operation of a poppet valve or the like, a rotary cam having a lobe elongated axially kthereof and of progressively varying width from end toend of the lobe, a follower having a head to be engaged by means for actuating the' valve and Valso having a roller riding said cam, said follower including an arm, a shifter adjacent the end of the arm opposite said head, means providingV a swivel connection between the shifter and said opposite end of the arm for effecting swinging movement of the arm upon actuation' of the shifter to steer said roller into selected position with respect to said cam lobe, and'means for normally urging said arm into a centered position with respect to said cam lobe.

10.' Inr combination in mechanism for controlling the operation of a poppet valve or the like. a'rotary cam having a lobe elongated axially thereof and of progressively varying width from end to. end of the lobe, a follower having a head to be engaged by means for actuating the valve and also having a roller riding said cam, said follower including an arm, a shifter adjacent the end of the arm opposite said head, means providing a swivel connection between the shifter and said opposite end of the arm for effecting swinging movement of the arm upon actuation of the shifter to steer said roller into selected position with respect to said cam lobe, and means for normally urging said arm into a centered position with respect to said cam lobe, said last mentioned-'means `comprising a tension spring 9 attached to said arm and a link attached to said spring and pivotally secured on a xed pivot spaced from and centered with respect to said lobe.

1l. In combination in mechanism for controlling the operation of a poppet valve, a tappet, said tappet having a foot provided with a broad downwardly facing surface, a rotary cam underlying said foot in spaced relation and having an elongated lobe of progressively varying width, a follower arm having a head underlying said foot and affording a bearing surface for said broad surface of said foot, said head surface being substantially elongated in the direction of elongation of said lobe, a roller carried by said head and riding said cam, a shifter adjacent the opposite end of said arm, and means effecting a swivel connection between said shifter and said opposite end of the arm for imparting steering angularity to said arm with respect to said lobe to cause said roller to ride into selected positions on said lobe to vary the duration of lifting of the tappet, said head slidably shifting relative to said tappet foot during the steering adjustment of the follower.

12. In combination in valve controlling mechanism, a valve actuator, an elongated rotaryl member of varying peripheral contour, a follower having a roller riding the periphery of the rotary member, said follower having a rst portion engaging said valve actuator and a second portion projecting clear of said rst portion, a member longitudinally pivotally supporting said second portion and carrying transverse pivot Y References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 807,835 Lyon Dec, 19, 1905 1,658,319 Wineman Feb. '7, 1928 1,688,164 Tarrant Oct. 16, 1928 2,137,081 Franke Nov. 15, 1938 2,266,077 Roan Dec. 16, 1941 2,397,511 Schreck Apr. 2, 1946 2,484,926 Bennet et al. Oct. 18, 1949 2,565,022 Hattink Aug. 21, 1951 FOREIGN PATENTS Number Country Date 388,123 France May 22, 1908 248,009 Germany May 3, 1915 551,726 Germany June 3, 1932