US 1666893 A
Description (OCR text may contain errors)
April 24, 19m
c. G. GARRARD 5 sneets-sheez 2 Filed Dec. 25. 1924 April124, 1928. A c. G. GARRARQ ."'MQHANISMLFOR PRODUCING CAM LIKE on SIMILAR IRREGULAR uo'rIoNs Filed Deo. 231924 s sheets-sheet s MMM Patented Apr. 24, 1928.
UNITEDl STATESr PATENT OFFICE.
cHAELEs'GEoRGE GARRARD, 0E LONDON, ENGLAND, ASSIGNoEro GEORGE STANLEY wALroLE, or LONDON, ENGLAND. i
MECHANISM FOR PRODUCING CAM-LIK OR SIMILAR IRR-EGrT-ILA'It MOTIONS.
Application filed December 23, 1924-, Serial No.y 757,598, yand in Great :Britain .Tune 5, 1924.
This invention relates to an improved mechanism for producing cam-like or simi-l lar intermittent motions.
As is well known a cam is a piece of mechanism which is used for changing a rotary motion into an intermittent reciprocating motion, and in this sense the motion pro duced by the device which is the subject ofy the present invention is cam-like. Thev invention can be applied to a very large va` riety of purposes for many of which cams have hitherto been used, and kit is mainly,
though by no means exclusively, intendedl for use in cases Where the desired movement r is to be effected against considerable pressure or 1n which frictional losses of energy are appreciable, and/or are to be avoided as ly to beveXerted, and losses of energy takey place, due to the friction between the cams and the surfaces contacting with them. The substitution of the present device for the cams enables considerable savings of energy to be effected, from which many advantages in operation accrue.
The device may also be utilized in printing presses, gold blocking presses, for operating the valves of internal combustion engines, and for many other purposes which need not be specified here.
According to the present invention the desired movement is produced by means of rolling bodies loosely mounted in a shaft or rotatable member and which roll on each other whilst the movement is being pro duced.
i In carrying the invention into effect ina convenient form, balls or cylindricalrollers are loosely mounted within atransverse slot of a rotatable shaft, mandril, vcage or the like, the outermost roller at each end of the slot protruding therefrom. The' excess of the diameter at the protruding balls over that of the shaft or cage should slightly exceed the distance of travel of the member to be actuated. In operation the said protruding rollers each bear against and roll on a roller track. In most 'cases of applying the invention one track is fastened to the frame of the machine and the other to t-he part to be moved relative thereto, but both tracks may be 'fastened to movable members.' The tracks may be either lflat or curved, their shape being designed'to give the intermittent motion of the character desired. Y* Three, five or other odd number of rollers are used. The intermediate roller or rollers, may if desired, be made of smaller diameter than the protruding rollers. The dimensions of the slot are such as to provide just sufficient clearance for the rollers to rotate freely each about its own aXis.
Vith an odd number of rollers, the motion of the rollers in 4contact with each other and with the twotracks isy pure rolling without.
rubbing or sliding. The invention is therefore particularly adapted to' produce inter-y mittenty cam-like movement under heavy ressure.`
Theballs ory rollers and *thev tracks are preferably made of hardened and .polished steel, as in ballbearing practice.
Any suitable means may be provided for retaining the rollers or balls within their slot and preventing them from falling out by gravity when owing to the position of the mandril, they are no longer supported by either of the tracks. For this purpose the edges o-f the slot maybe slightly turned over, or any other convenient means, not interfering with the rotation of the rollers, may be employed.
rIl append vention.
. Fig. l shows my cam device withone form of track.V c Y 2 shows the same structure with the drawings Aillustrating `the inrollerat right angles to its position of Fig.` 3 showsy a modification in which the upper track is a plane surface. y l
Fig. 4 is another modification showing cir-y cular tracks.
Fig. 5 is a still further. modification show# ing anotherform of track. g
Fig. 6 shows my invention applied toa valve structure.
Fig. 7 shows the invention applied to a press. fr a n In Figs. 1 and 2 the mechanism produces relative movement of two movable members', the two tracks have similar convex surfaces 6 over the operative portions, and a relatively rapidy movementA is produced. Fig.y 1 shows the two tracks or movableV members when closest together, Fig. 2 when furthest apart'.
In Fig. 3, the surface of the track 4 is similar to that in' Figs. 1 and 2, that of the track 5 is flat, and a slower movement is produced than that produced by the .mechanism of Figs. 1 and Q. One of the tracks 4 or 5 may be fixed to the frame ofthe machine', the rollers will then move aloi'i'g the slot when in operative action, as well as rolling on each other.
In Fig. 4 both tracks 4 and 5 are concave over the greater part of tlieir length at 6, andtheir interined'ia'te relative movement is very slow while the rollers are rolling on said concave parts, and very rapid when the 'rollers are rolling round the rounded cornersr.
In 5 the concave surface 6 of the track 4 is concentric' with the surface of the shaft 1, the concave surface 6 the track 5 is of `slightly greater radius of curv-ature and the relative movement produced is still slower thanu that given by' thev mechanismy of Fig. 4. The convex portions 7 ofl the two tracks are of much larger radius of curvature than in Fig. 4, and the correspending portion of the relative movement of the tracks 4 and 5 is more' gradual.
Fig. 6`I illustrates the inventionas applied in 4one form to operate the valves of an internal combustion engine.
Fig. 7 is a sectional view of an embossing or cutter crush machine operated by the in'- vention.
It will' be apparent that the improved mechanism can be put to many different uses and can be" compounded in various ways, thus for example, a n'iovement of the kind described can be utilized for operating the valves of internal combustion engines and the like or for" regularly operating. any desired assemblyA of reciprocating parts at regular and predet'ernii'ined intervals. In the ease of the valves ofa nmlti-cylinder engine the mandril can be provided with: a plurality of slots or holes arranged radially at vari-ous angles to `suit the desired timing and a separate set of rollers or balls will' be disposed within each slot or hole. The valve stein can' be arranged .in line soY as to project into the housingl for the mandril andI each valve stein willy then be' operated in turn whe-never the corresponding set of balls passes over' it.
Fig., 6 refersto an engine with overhead valves, and shows one convenient form' in which the invention may be carried into' ef rect. Many other arrangements arehowever possible. The shaft l is mounted. in a casing 8 fastened tothe valve casing or cylinder-head casting 10, which is fastened to or integral with the cylinder casting 11. The casing 8 is provided with acylindriealbore 9 coaxial with the shaft 1, on which the rollers 3 may roll with an easy fit. The fixedv tra-ck 4 is an adju-stable screw plug` and its operative contact surface G comprises a sphericalportmn of small radius. The movable track 5 is in the form of a guide piston or cap fastened to the end of' the valve stem 12and slidable in a vertical cylindrical bore 14 of the casing 8. The arrangement of the valve rod 12, cap 5land valve sp1-'ing' 15 is the usual well known one. The shaft is shown in an' aiigular position in which the valve is closed on its seating, and the rollers ance of the spring is transmitted' tlirough` 'the three rollers from the fixed' track 4 to the movable track 5, and that when the valve is full open and the `pressure greatest there is noA side pressure on any of the parts. In other positions of the4 valve during the opening or'vclosing movement there is only a slight side pressure ofthe movable track 5 onv t-he cylindrical bore 14, where r the sur face is ample, and of the two outerv balls 3' on; the walls of the slot 2; It is also t-o be observed that the valvey is opened and closed twice in each vrevolution of the shaft 4, which therefore ina four stroke cycle engine turns at one' fourth of they speed of the en'- gine crank shaft. l f
Further in a multi-cylinder engine, the slots 4, in the shaft 1 are ati different angles for each of the valves, and oneL setof` three rollers will be in operativel action'` between the fixed and' movable' tracks while other sets of rollers are rolling' on the bore 9i' of thevcasing. The ydevice therefore in" itself forms roller' bearings for the valve shaft 1, andno other bearings, exceptv to' locate the shaft longitudinally', are required.
Fig'. 6 shows the easenvitlr which thel in'- \f'e1`1tion'- can be adapted for overhead valves, doing away with tappet and levers and having extreinelly`7` light weight subjected' tothe cam motion, and aft the same time providing an' easy method' for adjusting thev valve clearance from the opposite side of the cam shaft to the valve' which is being opera-ted,
ywhich' adjustment can be made' while the also by the valve cap 5 ybeing similarly.V de- 4 signed and shaped.
The ball cam shaft 1 is not subjected to any pressure due to pushing open the valve, this pressure being betweenjthe adjusting screw and the valve cap, the ball cam shaft being subjected to torsion only and there fore requires supporting at the ends only,
the balls themselves supporting it right` along the housing ybore due to the fact that the holes for these three balls having to be bored at various angles around the shaft.
The relative timing betweenv valves and cylinders is fixed by the relative angles at practice.
which the slots in the cam shaft are bored, for the sets of balls or rollers. The bore must pass exact-ly across the centre of the shaft because this cam shaft requires to run at quarter engine speed, it having two positions at which valve is lifted. l
The bored hole into which the cam shaft is fitted should be of the same diameter as that over the three balls or rollers. The balls or rollers will then rotate at a continuous speed and Serve as a ball bearing support-- track 5 to the table 2O pivoted at 21 tothe frame.
The cam shaft 1 is shown in the position when the table is lifted yto its-extreme upper position, andthe work at` 22 is being pressed between the upper platen 23 fixed to the frame of the machine and the lower or movable platen 24 fastened to the table 20. The lowest position of the table 2O is determined by the movable track 5 resting on supports 25 in fixed relationshipto the frame, in which posit-ion the operative surface 6 of the track 5 is just clear of t-he surface ofthe cam shaft 1. The maximum pressure is exerted on the work when the mechanism is in or near the position shown in the drawings when 'a practically direct pressure'is `transmitted through the balls or rollers 3 from the fixed track 4 to the movable track 5 and thence to the Work at 22. Usual well known means are provided for adjusting the upper platen according to the thickness of the work and the pressureI to be exerted thereon, but these do not form any part of the presenty invention. In such machines the camshaft may be oscillated to and fro by a hand lever or operated in any other manner. l
1. A cam-like mechanism/for producing relative movement between two bodies from rthe rotational movement of a shaft, comprising two bodies, a cage on said shaft, said cage having a diametrical slot; an odd number of rollers, not less than three, loosely housed 1n saidslot, and tracks for saidrollers on said r-bodies, the' sum of the diameters ofthe rollers exceeding that of the cage and the rollers being adapted to roll upon they two roller tracks fixed relativelyto the said bodies.
2. Acam-like mechanism for producing movement of a machine part from the rota'- tional movement'of a shaft comprising two tracks forming part of the machlne, one being `fixed and the other movable, a cage 0n said shaft-having a diametrical slot; an odd f number of rollers, not less than three, loosely housed in said slot;`the sum of the diameters of the rollers exceeding that of the cage and the rollers being adapted to roll upon the fixed roller Vtrack in fixed relationship to the frame ofthe? machine and upon themovable roller track fixed relatively to the saidmaf chine part. 1
k3. A cam-like mechanism for operating embossing and cutter-crush machines v from the rotational movement of a shaft comprising a fixed and movable track on said machine, a` cage on said shaft having a dia-A metrical slot; an odd number, noty less than three', of `rollers looselyv housed in said slot; y the sum of the diameters ofthe rollers ex-l ceeding that of the cage and the rollers being adapted to roll upon the fixed roller track in fixed relationship with a stationary y pressurer member and vupon the movable vroller track' fixed yrelatively'to a movable Y pressure member of said machine. Y
4.*A'cam-like mechanism for producing the rotational movement of a shaft comprising a cage on said' shaft; a plurality of roll- I relative movement between two bodies from ers loosely housed in said cage; and roller ltracks fixed relatively to they said bodies; said cage being so constructed that the sum of the diameters of vthe rollers exceeds vthat of said cage so that' said rollers operate on said rollervtracks twice for each revolution of said cage.
. 5. In a cam-likestructure for producing intermittent harmonic motion from rotary motion, the combination With a cam surface of a rotating shaft, a cage on said shaft having a diametral slot therein and a plurality of rollers in said slot projecting above the surface of the cage, said rollers being adapti ed to move on said cam surface to exert a force thereon. Y
In testimony whereof, I have hereunto set my hand on 1924.
CHARLES GEORGE GARRARD.
this twelfth day of December,