US2414003A - Mechanical movements - Google Patents

Description

1947- T. H. THOMPSON MECHAN ICAL MOVEMENTS 4 Sheet-Sheet, 1

'Filed July 9, 1945 .[fivenivr TOM H. THOMPSON 2;; 7:219 aiiaf'neys Jan. 7, 1947. t 'T, H THOMPSQ 2,414,003-

MECHAN I CAL MOVEMENTS 1947- T. H. THOMPSON. 2,414,003

MECHANICAL MOVEMENiS Filed July 9, 1943 4 Sheets-Shet 3 Jan. 7, 1947. T. H. THOMPSON MECHANICAL MOVEMENTS Filed July 9, 1945 4 Sheets-Sheet 4 TOM H. THOMPSON 6y kzls azivrneys Patented Jan. 7, 1947 MECHANICAL MOVEMENTS Tom H. Thompson, Larchmont, N. Y., assignor to Builder-Thompson Engineering and Research Corporation, New York, N. Y., a corporation of Michigan Application July 9, 1943, Serial No. 494,071

8 Claims. (Cl. 74-571) This invention relates to mechanismand method adapted to convert rotary motion to or from reciprocatory motion by means of a straight-line motion, i. e., the motion of a connecting rod of theoretically unlimited length. The mechanism is of a type in which two circular eccentrics, one inside the other, are employed to cause the conversion. The object of the invention is to obtain adjustment of the length of the reciprocatory movement in a simple manner. It is characteristic of the invention that each of the two circular eccentrics above mentioned is itself divided into two eccentrics of equal lift and that the opposite rotation of the eccentrics in a pair gives the change in length of the reciprocatory motion while simultaneously the relatively opposed rotation of the inner and outer pairs of eccentrics causes-translation of the reciprocatory motion into rotary motion. It is also characteristic of the preferred form of the invention that when the lift of one of the eccentrics is changed, the lift of the other eccentric automatically adjusts itself to equality.

In my Patent No. 2,316,114, dated April 6, 1943, for a Machine element, there is shown a mechanism for translating rotary motion to or from reciprocatory motion by means of a straight-line movement which theretofore had been obtained by the well-known Scotch yoke. The two circular eccentrics, one inside the other, of that prior patent are embodied in the present invention, which may be considered an improvement upon that earlier invention. The subjects-matter of my pending-applications Ser. No. 481,336, filed.

March 31., 1943, and. Ser. No. 403,896, filed July 24, 1941, are also embodied in the mechanism shown in the present application.

' 'In straight-line motion mechanisms in which two circular eccentrics, one inside the other, are employed in connection with the conversion of rotary motion to or from reciprocatory motion,

.the two eccentrics revolve in opposite directions to give the reciprocatory motion. In the present specification the elements which go to make up the inner eccentric will be termed the primary eccentric assembly, and the elements which go to make up the outer eccentric will be termed the secondary eccentric assembly. The two eccentrics cooperate together to accumulate the total lift. The movement of each assembly as a unit with relation to the other assembly should be distinguished carefully in function from the movement of the elements within one assembly with relation to each other. in obtaining the variations in length of the part of the reciprocatory movement contributed by that assembly. It is this latter type of movement which is the primary object of the present invention.

In modern engines, pumps, compressors, brakes, torque converters, metering devices or other mechanisms where a mechanical movement such as above described is used, it is frequently desirable that the length of the reciprocatory move ment be variable. In some mechanisms itis even desirablethat the direction of an oscillation be reversed, as far as concerns its'timed relation to the rotary movement. If, for example, a mechanism of this type were employed in a pump, the time of projection of the pistons could sometimes be changed to advantage so as to cause the pump to push the water or other liquids in the reverse direction without stopping the drive of the-pump. Again, if the mechanical movement were em-jployed in a device such as an airplane engine, it would be possible to change the direction of rdtation of the propeller without stopping the engine. In the mechanism which I employ, the same elements which give the reciprocation are progressively used to reduce the lift or reciprocation to zero and then to increase the lift in the opposite direction. As shown, for example, in my saidprior application Ser. No. 481,336, the cylinders are arranged in a radial manner in a rotor. The rotation of the rotor need be merely relative to the shaft associated with the primary eccentric-that is to say, it may be the primary which will do the rotating, and the rotor containing the cylinders may be stationary. The present invention can be employed in either type of device.

Speaking generally, the present invention contemplates splitting the primary and secondary eccentric assemblies each into a pair of eccentrics. Each of these four elements is in itself an eccentric embracing 0r embraced by the companion element with which it goes to make up one eccentric pair.

In the drawings:

Fig. 1 is a view in elevation, partly broken away, of a rotary pump made in accordance with my invention, viewed from the control end;

Fig. 2 is a view in elevation of the control end plate of the pump of Fig. 1;

Fig. 3 is a view similar to Fig. 2 showing the parts adjusted for full stroke;

Fig.4 is a vertical view partly in section on th axis of the rotor through the pump of Fig. 1, taken on the line 4-4 of Fig. 1;

Fig. 5 is a view in vertical section in a plane normal to the axis of the rotor taken on the line 55: of Fig. 4;

Fig. 6 is a view in horizontal section of the pump of Fig. 1, seen along the axis of the rotor taken on .the line 6 of Fig. l, with the pump at zero stroke;

Fig. 7 is a view in vertical section similar to Fig. 5, showing the parts in full stroke;

Fig. 8 is a detail view of one piston and cylinder of Fig. '7, at another rotational position;

Figs. 9 to 11 inclusive show the means articulating the secondary assembly; Fig, 9 being an end view of the three eccentrics at zero stroke position; Fig. 10 being a view of the parts in side elevation at zero stroke; and Fig. 11 an end elevation of the parts at full'stroke;

Figs. 12 and 13 are diagrammatic views of the movements of the eccentrics and yoke about pump center, Fig. 12 showing the parts at .zero stroke, and Fig. 13 the same parts at the end of a stroke; the small dotted circle indicatingpump center.

The invention will be shown and described embodied in a pump, i. e., a device in which rotary motion is being converted into reciprocatory motion. In order to simplify the description of the machine, I will first describe .the movement of the parts when in motion during constant operation and while no adjustment of the stroke or lift is being made. Then I will draw attention to the mechanisms and connections which make it possible'to adjust the stroke.

It should be noted that the movements of the parts are relative and that while in the example shown in the drawings the primary eccentric assembly does not rotate when the machine is merely pumping, the cylinders and pistons rotate. In other words, the device, in analogy to the terminology for engines, is a rotary pump, i. e., the cylinders and pistons rotate about the pump center and the casing stands still. The invention, of course, is equally useful in a radial pump or engine, 1. e., one in which the cylinders do not rotate and the relative motion is obtained by rotation applied at the primary assembly. The principal parts of the easing are the drive end plate 301, the rotor .housing 302 and the control end plate 303 (see Fig. 6)

Mounted for rotation about pump center is a rotor 40 in which are six radial openings constituting the cylinders in which pistons 60 reciprocate radially. These Openings are distributed equi-angularly about pump center. The rotoris turned by a drive shaft 50 which passes freelythrough an opening in the drive end plate and is connected directly to the rotor by a flange 402.

The piston 50 in each cylinder is connected to a piston in the cylinder diametrically opposite to it. forming one unitary element, as can be seen in Fig. 5. As can be seen in this side elevation, the pistons and piston rods 602 are connected by a yoke 60! and the circular eccentrics which cause them to reciprocate are located in this yoke. This unitary structure can be termed the yoke element. The length of the element is such that when one'piston is fully retracted its mate is fully advanced. There are six istons in the preferred embodiment-shown in the drawings. The pistons arearranged in equi angular relation so that the cylinders .in the rotor are 60 apart. If a different number of pistons are used, the angle between two pistons will be different. The number of pistons should be even.

It will be seen thatthe yokes Bill and pistons As already mentioned, in the form of pump shown in the drawings the obtaining of the necessary reciprocatory motion involves the rotation of the rotor and pistons 00 and the holding stationary of the elements which are functionally at the other end of the machine element. These elements are the inner torsion equalizer shaft 10 and the primary inner eccentrics 80, which will be described next.

The eccentrics are divided into two pairs, the inner pair being known as the primary assembly. In this primary assembly the inner part is turned "inside out in a manner similar to that in which the primary is turned inside out in my application Ser. No. 403,896, above referred to. This is a source of simplicity of construction andwhat is probably even more importantcompactness. The primary inner eccentric consists of the round, so-called torsion equalizer shaft 10 held in an eccentric position with relation to pump center by two inner eccentrics 80 which support it at its ends. These two eccentrics 80 are keyed on the shaft 10 and are held in position by roller bearings 80! (Fig. 6) which in turn are supported by the end plate 305 and flange 402. The end plate 305 at the control end of the housing is bolted to the housing end plate 303 and can be seen in Figs. 2, 3, 4 and 6. Except when the stroke of the pump is being adjusted, there is no movement of the roller bearings BM in the stationary end plate 305. The flange 402 supporting the eccentric 80 at the drive end of the housing is bolted to the rotor 40 and the drive shaft and rotates with them. There are roller bearings 403 between .the outer shoulder of the flange 402 and the stationary drive end plate 3!" of the casing. The means for adjusting the stroke and which keeps the inner primary eccentric from turning at other times will be described later.

In the so-called reversal of the primary inner eccentric, the small torsion shaft 10 occupies only a. minimum diameter which makes it possible to have the primary outer eccentric 9E3 lie within the radial dimensions of theeccentrics 60. This outer eccentric 90 extends the complete distance between the two eccentrics and, like the eccentrics BU-except when the stroke or lift of the pump is being changed (as will be explained later)--turns with the torsion shaft i0 and the eccentrics 80. These elements, by turning ,in the one direction, combine with the secondary eccentric assembly turning in the opposite direction, to give the lift or stroke of the pump.

It will be noted that with the primary inner eccentric reversed and the primary outer eccentric member of straight uniform diameter, the eccentricity 0r lift transmitted to the secondary assembl does not occur around the center of the internal diameter of the secondary eccentric assembly, where the lobes of the latter element are spaced. When the stroke of the primary is be ing adjusted the torsion shaft 10 .moves up and down a predetermined center line of the pump.

As in the case of the primary eccentric, the secondary eccentric also is composed functional- -ly of two main elements-an inner and an outer eccentric. The inner part or element of the secondary eccentric may also be termed a main cam shaft. In the structure shown in Figs. 5 and 6 of the drawings, it is composed of two parts, a single ribbed unitary sleeve I00 and three eccentric lobes i0l for the pairs of pistons spaced around the element in equi-angular relation. These angularly spaced pistons are about 60 apart, as can also be seen, for example, in my application Ser. No. 403,896, above referred to. There is a space between each lobe and its neighbor in which to place articulating disks, to be described later.

In distinction to the inner secondary cam or eccentric cluster I00, the outer eccentrics'for the three pistons are separate from each other and each surrounds merely its own lobe of the inner part of the secondary eccentric. These outer eccentrics are designated in the drawings by the reference characters III], III, H2. If desired, roller bearings H3 can be placed between the outer secondary eccentrics H0, HI, H2 and the yoke 6M, and smaller roller bearings I M can be placed between the inner and outer secondary eccentrics.

It will be well at this point to review the general manner of operation of the four eccentrics which constitute the primary and secondary eccentrics. While each pair of eccentrics can be functionally considered as one eccentric in certain'respects, I shall call each pair of eccentrics and associated parts an eccentric assembly. When the stroke is not being changed, 1. e., adjusted or varied, the two eccentrics of the primary assembly turn relatively in one direction with a fixed lift, and the two eccentrics of the secondary assembly turn in the opposite direction with. a

.fixed but equal lift providing the cumulated or total lift. This causes reciprocation of the pistons. As long as one pair of the four eccentrics is so mounted that the eccentrics in that pair are not at liberty to turn with relation to each other,

it has been found that the eccentrics forming the 1 other assembly will not change their relation to each other. I have discovered that with the structure shown, despite the lack of direct connection between the parts, the lift of the primary and secondary eccentrics will automatically maintain equality if the two elements of one eccentric are rotated in opposite directions with relation to each other. Thus, for example, in the pump shown in the drawings if the parts 80 and 90 of the primary eccentric are turned slightly in opposite directions from the positions shown in Figs.

6 and '7, thereby changing the lift of the primary eccentric, the combined effect of the change in the primary and of the yoke opening 69! is simultaneously to cause the two parts of the secondary eccentric to rotate in opposite directions,

thereby equalizing their lift to that of theplimary eccentric. I believe it to be novel to have two cams or eccentrics, one inside the other, rotating in opposite directions to cause reciprocation of a third element, and at the same time to so construct each of those two eccentrics that the lift of the two eccentrics can be changed while the mechanism is continuing to cause reciprocation of the third element, and to do this in such a manner that the machine automatically keeps the lift of the two eccentrics equal.

I will now describe the mechanism which is the direct or primary means of adjusting or varying the stroke or lift of the pump. The fundamental requirement is that the two eccentrics which with their associated parts constitute the primary eccentric, may be rotated slightly in opposite directions. Since the two eccentrics are circular ec centrics, it will be seen that the cumulated lift of the primary will be changed. It will be changed, for one thing, in the maximum lift to be obtained from the primary assembly because the high points of the inner and outer eccentrics 8 0 and 9B are further separated than heretofore cams and torsion shaft l3 clockwise. mechanism to do this can be seen in Figs. 2 and It may be noted at this point by looking at Fig. 7

order that the reader may not be confused, it is pointed outthat the outer primary eccentric 9! and the elements 10 and 80 composing the primary inner eccentric are not rotated relatively to each other to give a higher lift than is shown in Figs. '7 and 13, and therefore the maximum theoretical lift of the primary will not occur. The effective lifts of the inner and outer eccentrics are equal.

Figs. l2and 13 are merely diagrammatic illustrations of the positions of the eccentrics and yokes at zero and full stroke of the embodiment of the invention shown in the drawings. These correspond to Figs. 9 and 11. The small dotted circle in each case is pump center and the smallest solid circle is the position of the inner torsion equalizer shaft 10 and of the inner primary eccentrics 80.

As already referred to, in the example shown in the drawings, the manual adjustment of the stroke of the pump is obtained by movement of the primary eccentric assembly only. The parts about to he described can be seen best in Figs. 1 to 4, and in Fig. 6. The manual adjustment is rotational in a plane normal to the drive shaft 50 and it is controllably obtained by rotation of the hand-wheel fill located on the upper end of a worm screw shaft 102 carried by a bracket 1&3

mounted on the outer end of the flange 364 on the control end plate 393 (Fig. 4). The rotation of the worm screw shaft 102 is translated into verti cal movement by means of a primary control block 164 threaded on theworm screw shaft and guided vertically by the bracket 563. This block is connected to the inner and outer eccentrics of the primary eccentric assembly by two arms 1'65, 106 which extend laterally on opposite sides of the screw shaft M2 at a level approximately opposite the center of the drive shaft 5%. Each of these arms provides the necessary turning adjustment for one of the eccentrics of the primary assembly. The angular movement of the eccentrics caused by these arms is equal. Thus the arm at the left of the screw shaft m2, as viewed in Fig. 1, connects with the outer primary eccentric 9i] and the right arm 16% serves to turn the inner eccentric cam 3&1 and torsion shaft H1. As can be seen in the vertical sectional view, Fig. 6, the left arm Hi5 has a horizontal slot 10? in which slides the outer end of a pin Hill mounted in a collar 139 which fits around the outer eccentric 99 and is keyed thereto by key l iii. There is an open slot H5 in the end plate 335 to permit the movement of the pin F98 without conflict with the end plate. It will be seen that unless the screw shaft 702 is turned, the primary control block Hi4, arm Hi5, collar led and key Hi3 will serve to hold the outer primary eccentric 99 against rotation, but that if the screw is turned, the resultant raising or lowering of the arm Hi5 will rotatethe eccentric. Lowering of the control block H14 will turn the eccentric counterclockwise, as viewed in Fig. 1. Correspondingly, lowering of the control block 164 will serve to turn the The '3 and in the .upper right-hand corner of Fig. 6.

There is a slot 10? in the arm 106 corresponding to the slot in the arm 195 and moving horizontally in that slot H3! is a pin l'l I fastened in the end of an arm H2 (see Figs. 2 and 3). This arm is mounted on the end of the torsion shaft '10 by a screw l 53 and is locked to the cam 80 at the right end of the machine by a pin 1 it (see Fig. 6). The screw 7 I3 and the pin H4 are on opposite sides of pump-center and swingingthe arm 1 I 2 causes rotation of the cam 89 and the torsion shaft 10 an equi-angular amount. The cam 80 at the other end of the torsion shaft is rigidly fastened on the shaft and therefore turns with the shaft and the first-mentioned cam 80. In Figs. 1, 2, 4 and 5 the parts are shown set at zero, the position in which no lift is caused by turning of the rotor 40. In Fig. 3 the block 194 is shown lowered to the maximum degree used in the machine, which corresponds with the position of the parts in Figs.

6 and '7.

As set forth in my previous applications, the mechanism herein used is a straight-line motion mechanism in which circular eccentrics are used that are mounted one inside the other and which occupy the entire space inside the element next outside of it. The outside eccentric of the secondary assembly fills the entire space inside its yoke 60!. With circular eccentrics so embraced, I have found that adjustment of the two eccentrics forming the primary assembly by means of turning the screw shaft 102 will cause the secondary assembly to adjust its eccentricity automatically to equal that of the primary. This, of course, simplifies the mechanism needed and only manual adjustment of the primary assembly is necessary to cause the entire apparatus to be adjusted to the new setting. (It is fundamental in straight-line motion mechanism that circular eccentrics be used inside one another with the lift of the primary and secondary means at all times equal.) I have found that this adjustment takes place in spite of the fact that one part of the secondary assembly rotates in one direction and the other part in the opposite direction. The mechanism shown in the drawings, however, does have dead center at the top and bottom positions of the rotor and for those positions it is advisable to provide means insuring that the direction of rotation of the eccentrics does not change. Thus it is possible at those dead center positions for the secondary assembly to go into greater or lesser lift positions. I have devised the following novel means of preventing this and overcoming other objections which will be mentioned as the description proceeds. In the first place, the outer eccentrics of the secondary assembly are kept in equi-angular relation to each other by the articulating means which will be described hereinafter, so that a common point on one, in the case of the mechanism shown in the drawings, is 120 away from the corresponding point at the neighboring outer eccentric, regardless of the position that any such outer eccentric is in with relation to the lobe of its inner eccentric. I also find that it is useful for the proper functioning of the mechanism to have the equal radial disposition of the cylinders about the periphery of the rotor. The fixed relation of the three lobes of the inner eccentric of the secondary assembly also performs a function in proper operation of the device, and with these features each secondary unit is helped past its dead center position by the other two units, and the adjustment of the eccentricity of any secondary unit to equal the adjustment of the primary assembly takes place automatically whether the pump is standing still or operating.

If we were dealing with a construction in which there was only one yoke Gill and one outer secondary eccentric, the secondary assembly would have to be adjusted simultaneously with the primary assembly by means connected to the secondary.

It will be obvious from the description heretofore given that the rotor turns in a clockwise direction as viewed in Fig. 5 and that as a result of that turning the pistons move radially back and forth in their cylinders between the bottom and top positions shown in Fig. 7. At the bottom and top positions the periphery of the rotor is in contact with filler pieces 504, 405 which present curved contact faces to the periphery of the rotor. As can be seen by comparing the positions of the parts in Fig. 7 and in Fig. 8, this separating of the plates around the periphery of the rotor inside the casing in the two parts makes it possible to give apumping action. As seen in Fig. 7, for example, there is a space outside between the rotor and the inside of the casing which is tapered from the inlet port 406 toward the filler pieces 494, 495, and the tapered structure exists between the filler pieces and the discharge outlet 467. It is believed that the operation of the device will be obvious from the description heretofore given, but it is desired to point out that the direction in which the liquid is pumped can be changed if the adjustment of stroke above described is carried to the opposite side of the zero position (pump center) shown in Figs. 1, 2, 4 and 5. Thus if the block 104 were screwed upwardly instead of downwardly, the torsion shaft it! would be moved in a straight line to the other side of pump center, causing the top piston in Fig. '7 to go to the top point of its stroke. It will be seen that there would be liquid in the cylinder as it is cut off from the discharge outlet dill by the filler piece 405 and that the subsequent movement of the cylinder would carry it into contact with the port 306 which theretofore was the intake port, and the piston would push the liquid out into that port. The effect of changing the timing of the pistons in this manner in a pump is to make it possible to change the direction in which the liquid is being pumped, without stopping the rotation of the drive shaft at all. The advantages and uses of such a construction will be obvious. This is especially true when it is taken in connection with the fact that the output of the pump can be varied. Similarly through a hydraulic torque converter the speed or direction of rotation of the drive shaft of the fluid motor can be varied. In other words, by simply changing the setting of the two eccentric elements of one of the eccentric assemblies in the mechanical movement, it is possible to go to any other portion of a complete cycle of movement.

Stated another way, my invention provides mean whereby a full stroke in one direction can be changed to zero stroke, passing through the zero point into a full stroke in the opposite direction while the machine is operating, without changing or altering the position of the driving means itself. In. this statement I am assuming that we are dealing with a pump of the type mentioned in the opening of the specification; and by driving means I refer to the drive shaft. The same principle will apply in the case of an engine.

There i another novel feature shown in the drawings. This is the articulation. As above mentioned, it will be noted that the outer elements of the secondary eccentric assembly for each piston element are free and independent of each other. (I have already pointed out that they have no fixed connection to the other elements of the secondary eccentric to which each one belongs.)

In placing three outer secondary cams upon a shaft consisting of three inner secondary cams at 120 relation to each other, these outer secondary cams must bear a constant rotational relation to each other at all times to insure the operation of the variable assembly. Thus where there are three outer secondary cams they should always b at 120 relation to each other, regardless of how the stroke resulting from the entire secondary assembly is varied. Owing to the fact that the lobes of the three outer elements of the secondary eccentric are set 120 apart, so that the outer eccentrics are turning about different centers, there are no points on the complemental faces of any two of the outer eccentrics opposite each other which remain in fixed relation to each other when the lift of the secondary eccentric is changed.

I have shown in Figs. 9, and 11 a form of means for articulating the outer secondary cams so that they are always 120 apart, regardless of their relation to the inner secondary cams, this mechanically preferable construction involving the use of diiferential disks and cranks. Thus in the side view of Fig. 10 the three secondary cams Hil, HI, H2 have differential disks H5 located between them which are free to rotate on the inner secondary member about the common center of that inner secondary member. These articulating differential disks rotate in relation to the inner secondary cam assembly one full revolution for every full revolution of the inner secondary eccentric member. tation is not at a uniform rate, its variable speed is governed by the relation of the cams with which it is joined by the cranks H6. This can be seen from Figs. 9 and 11. These cranks H6 are able to swing radially outward at one end as the diameter of the path of the outer secondary cams increases. It will be observed that there is a crank H6 from each cam to the adjacent diiferential disk I I5, and another crank from the differential disk to the cam ring eccentric 0n the other side or the disk. This construction takes care of itself automatically and keeps the lifts equal. The connections between disks and the eccentrics are necessary because the points of connection are not at the points of intersection of the lift lines of the two eccentrics, nor are they in common relation to the center lift line.

It will be seen that the pump which I have described i one which has no operating crank, and that I hav produced a variable pump in which two sets of two eccentrics each, with equal effective lift, by working simultaneously in oposite directions provide reciprocation of a third member, but at the same time the individual assemblies of the sets of eccentrics are variable at will with relation to each other in a very simple manner while the pump is working. It is always possible to vary the stroke and keep th effective eccentricity of one assembly to the other equal, as is necessary in a device of this type.

What I claim is:

1. In a straight-line mechanism for converting rotary motion to or from reciprocatory motion, a primary eccentric assembly comprising two co- While its rois operating circular eccentrics and means for adjusting said eccentrics to vary the lift caused thereby and for locking these two eccentrics in adjusted positions a secondary eccentric assembly acted upon by said primary eccentric assembly and comprising a unitary inner member having a plurality of eccentric lobes side by side spaced around the member equi-angularly and an outer eccentric on each lobe and means associated with the secondary assembly keeping said outer eccentrics spaced apart equi-angularly; reciprocating elements embracing said outer eccentrics and means guiding said reciprocating elements wherebyrelative rotation of the primary and-secondary assemblies in opposite directions causes conversion of motion, and adjustment of the locking means varies the lift of both primary and secondary assemblies equally.

2. In a straight-line harmonic motion mechanism for converting rotary motion to or from reciprocatory motion, driving and driven connections, cooperating primary and secondary eccentric assemblies and reciprocatory elements embracing the secondary eccentric assembly, said primary assembly comprising a pair of co-operating circular eccentrics and means adjustably controlling the relation of the two eccentrics relatively to each other, thereby controlling the lift of the assembly; said secondary assembly engaging said primary eccentric assembly and comprising a plurality of circular inner eccentrics in fixed equi-anguiar relation to each other about a common axis but lacking rigid connection to any other part of the machine, an outer circular eccentric surrounding each such inner eccentric and surrounded in turn by one of the driven or driving connections and means for guiding said connections in equi-angularly spaced paths of reciprocatory movement, whereby when the lift of the primary assembly is adjusted the secondary assembly automatically assumes equal lift.

3. In a straight-line harmonic motion mechanism for converting rotary motion to or from reciprocatory motion the combination of primary and secondary circular eccentric assemblies of equal lift adapted to act one on the other, the primary of said eccentric assemblies comprising two co-operating circular eccentrics and means associated with said primary eccentric assembly adjustably controlling the lift, the secondary of said eccentric assemblies lacking rigid connection to any other part of the mechanism and comprising a unitary element engaging said primary eccentric assembly and having a plurality of eccentrics rigidly fixed side by side with their lobes in equi-angular relation to each other about a common axis, a circular eccentric on each such lobe and a reciprocatory element surrounding each such eccentric, means guiding said reciprocatory element and means maintaining each eccentric on said lobes in fixed angular relation to the other eccentrics on said lobes, whereby when the lift of the primary eccentric assembly is changed by its adjustable control, the secondary assembly automatically equalizes its lift to that of the primary assembly.

4. In a straight-line harmonic motion mechanism for converting rotary motion to or from reciprocatory motion, primary and secondary pairs of co-operating circular eccentrics, means adapted to lock the primary pair of eccentrics together, said means also being adapted to adjust the lift of the said pair of eccentrics by rotating them in opposite directions, the secondary pair of eccentrics comprising an inner group of eccentrics with anagooa lobes arranged in fixed equi-angular relation to each other about a common axis and engaging one of said primary pair ofeccentrics and an outer eccentric group'consisting a circular eccentric surrounding each lobe of the inner eccentric group, in combination with a driving or driven connection embracing each outer eccentric, and means guiding said connections in equi-angularly spacedpaths of reciprocatory movement whereby when the lift of the primary assembly is adjusted the secondary assembly automatically equalizes its lift.

5. In a straight-line reciprocating mechanism adapted to'change rotary motion to or from reciprocatory motion, the provision of four circular eccentrics forming cooperating eccentric assemblies consisting of pairs of adjacent eccentries, the reciprocatory motion being functionally applied'or received at the periphery of one of said eccentrics, said pairs of adjacent eccentrics being constructed and arranged to have relatively opposite rotation as'units to give the conversion of motion to' or from reciprocatory motion, and

means adapted to cause movement of the two eccentrics of said pairs equally in' opposite directions with relation to each other for the purpose of changing the length of the reciprocatory movement.

6'. In a straight-line reciprocating mechanism for converting rotary motion to or from reciprocatorymotion, a primary eccentric assembly ad'- justabl'e as to its lift, a secondary or outer eccentric assembly comprising an inner member having a plurality of eccentric lobes side by side spaced around a center in fixed equi-angular relation, and an outer eccentric on each lobe, in combination with articulating means linking said outer eccentrics together in equi-angular relation 12 at all times, whereby the secondary assembly is maintained in proper timed relation.

7'. In a straight-linereciprocating mechanism for converting rota-ry'motion to or from reciprocatory motion, aprimary eccentric assembly adjustable as to its lift, a secondary or outer eccentric assembly comprising an inner member having a plurality of eccentric lobes side by side spaced arounda center in fixed equi-angular rela tion, and an outer eccentric on eachlobe, in combination' with means adapted to cause movement of theinner and outer eccentrics of the secondaryassembly with relation toeach other for thepurpose'of changing the lift of thesecondary assembly, and articulatingmeans holding said outer eccentrics together in'equi-angular relation when the-eccentrics are-rotating oppositely to the inner secondary member to change the lift.

8; In a straight-line mechanism for converting rotary motion to or from reciprocatory motion, the provision of four co-operating circular eccentrics forming primary and secondary eccentric assemblies of 'pairs of'eccentrics with 'said secondary eccentric assembly surrounding said primary eccentric assembly, a yoke surrounding an eccentric of said secondary assembly to and from which eccentric the reciprocatory motion is given or received, means guiding thereciprocatory movements of said yoke in combination with adjustable control means adapted to-adjust the-relative-positions of theprimary pair of eccentrics to each other and of the secondary pair of eccentrics to-each other and thereby adjust the lift, whereby the application of motion to the yoke will causerotation of one pair with a lift equal tothe lift ofthe-other pair of eccentrics.

TOM H. THOMPSON.

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