US1964900A - Gearing for performing movements with intercalated periods of standstill - Google Patents

Description

July 3, 1934. l H. ALT 1,964,900

GEARING FOR PERFORMING MOVEMENTS WITH INTERCALATED PERIODS OF STANDSTILL Filed Sept. 15, 1930 2 Sheets-Sheet. 1

H. ALT 1,964,900

GEARING FOR PERFORMING MOVEMENTS WITH INTERCALATED PERIODS OF STAN'DSTILL July 3, 1934.

Filed Sept. 15, 1930 2 Sheets-Sheet 2 Patented July 3, 1934 PATENT OFFICE GEARHNG FR lFlERlFRlWllNG MVlEll/HENTS WITH INTERCLATED l? E R ll 0 D S 0 1F STANDSTILL Hermann Alt, Klotzsclie, near Dresden, Germany Application September 15, 1930, Serial No. 482,123 In Germany September 18, 1929 Claims.

For performing movements into which periods of standstill are to be periodically inserted it is customary to make use of cam mechanism in which the curved parts that serve for producing 5 the periods of standstill are so designed as to be located centrically with respect to the axis of rotation of the cam. Gearings of this type suffer, however, also from that drawback from which all other cam mechanisms suer, viz. the diilO culty to manufacture accurate cams and the uncertainty of their action, as, unless double cams are used, it is necessary to press the follower roll firmly against the cam disk; furthermore, it is very difficult, if not impossible, to re-adjust l5 the individual periods of time for standstill and for motion, and finally, the cams are exposed to great wear and tear whereby the motions are rendered inaccurate.

The present invention relates to a gearing that is free from the above-mentioned drawbacks and makes it possible to perform 'movements of the kind stated solely with the employment of simple 'turnable joints, including sliding members. The invention depends on the fact that, as is known from the art of designing gearings, every point of a so-called coupling plane or link of an articulated quadrangle linkage describes a coupling curve as its locus. If a circular arc that corresponds to the curvature of that part of the curve is substituted for a part of this curve and if the point describing `the locus is connected with the centre of curvature of that circular arc by means of an articulated rod or link, then that centre of curvature when being guided in any desired way will be stationary while the coupling point passes through the part of the circular arc, but the remainder of its motion will be rectilinear or corresponding to its guide. There will be obtained in this way a movement or path of said point into which periods of standstill are periodically inserted.

It is, it is true, known in connection with centric coupling gears and centric crank gears to articulate a rod to a point lying either directly on the connecting rod or in the direct elongation of it, thelength of that rod corresponding to the radius of curvature of a portion of the curved path or locus described by the respective point of the coupling rod, so that the point at 50 the end of the rod performs amovernent with an inserted period of standstill. These known gearings are, however, suited solely for a certain special purpose, as in every case the connecting point lies either directly upon the couplingrod or in a direct elongation thereof.

The present invention utilizes the discovery that not only such points can be used which lie directly on the connecting rod or in a direct elongation thereof, so as to partake ofA its motion, but which that also other points which are connected with a rod moved in a plane or in space, but lie remote from that rod, can'be employed to attain the object in view. When making use of such points which lie remote from, or outside, the moved rod the advantage is attained that in order to obtain the desired motion it is necessary that a special gearing be designed or built into the respective machine, but any gearing a1- ready existing in that machine and serving for another purpose can be used, in that a point is selected from which the motion is to be transmitted and that that point is connected with a moved rod of the existing gearing.

The invention is illustrated diagrammatically and by way of example on the accompanying 76 drawings in which Figure 1 shows a constructional form of a gearing designed according to this invention, and Figure 2 shows a modification thereof. Fig. 3 shows a mechanical movement embodying the invention, in elevation; Fig. 4 80 is a'partly sectional end View of the same, and Fig. 5 is a diagram illustrating the motion produced.

In Fig. 1, A, B, C and D are the four points of connection of an articulated quadrilateral, the side A-D of which isstationary. B-C is the connecting link, and the plane to which this rod pertains is the coupling plane. The rod B-C must be assumed to be movable in this plane. When the rods A-B, B-C and C-D are moved, 90 every point of the rod describes a so-calledcoupling curve or locus. We will assume that E is a point which is rigidly connected with.the rod B-C. When the rod A-B is moved or turned completely round so as to make ne complete revolution, the rod C-D will perform a complete oscillation, that is to say, the point C will be moved first in the one direction and then in the reverse direction for a certain length of way, and the point E will describe an oblong or end or point F of said rod E-F is guided in any desired manner, but corresponding to the motion to be produced, in the example shown in Fig. 1 the end or point F is connected by a rod or link F-G with the stationary point G so that the point F describes short circular arcs having the point G as centre.

When the articulated quadrilateral is moved, that is to say, when the rod or, say, crank-arm A-B, is moved round, or rotated, the point E will describe the closed curve or coupling curve E, E, E and the point F will either oscillate or move completely round the point G, according to the lengths of the parts concerned. It will be obvious that if FG is very long, the point F will describe practically a straight line. But during that time in which the point E is moving from the point E to the point E", or reversely, depending on the direction of rotation of the rod or crank-arm A-B, the point F will not be moved; it will be at a standstill during that time, because the length E-F corresponds to the radius of curvature of the curve arc EE". The point F will, thus, alternaly oscillate and be stationary.

In Fig. 1 the curve B'-B corresponds to the curve portion E'-E, that is to say, while the point B is moving from the point B to the point B", the point E is moving from the point E' to the point E", and the point F will, thus, be at a standstill While the rod or crank-arm A-B is moving through that portion of its circular path which commences at B' and ends at B", or reversely, according to the direction of rotation of said rod or crank-arm.

In the coupling plane of any desired articulated quadrilateral innitely many points E and F that form pairs can be chosen. The choice of how the point F is to be guided must be accommodated to the individual cases. Although the dimensions of the articulated quadrilateral can be chosen at liberty, still, certain denite conditions depending on the particularities of the individudl cases can be responded to by suitably ascertaining or determining or choosing the dimensions of one or the other member, or all members, of the respective quadrilaterals. Instead of guiding the point F in a circular curve or in a circle it is also possible to guide it rectilinearly, in other words, in an arc of a circle of innite radius, in which case the rectilinear motions will alternate with periods of standstill. The extent of the move-1 ment of the point F, and the manner in which it is moved. depend, of course, upon the coupling curve and, thus, also upon the design of the articulated quadrilateral, furthermore upon the choice of the coupling point E.- If a definite motion for a point of a gearing is sought, then the shape of the corresponding articulated quadrilateral, the position o'f the coupling point E, and the manner of guiding the point F, can easily be found by a geometric construction or by trials or also by computation, always in such a way that denite prescribed periods of motion and periods of standstill result.

The point F can be guided also in any other desired manner and, therefore, for instance, any desired curved guide member may be used. It is also possible to guide the point F in such a Way that it is moved out of the plane of the drawings.

The constructional form of the gearing, as shown in Fig. i, can also be designed in such a manner that it is adjustable if this is necessary in any given practical case in which that gearing is to be employed. Thus, for instance, one or the other or all of the four members constituting the quadrilateral may be variable in length, or the point E may be shiftable, or the length of the rod E-F may be variable for instance in that the point F is located in a slot provided at the end of the rod or link extending from E to F, the arrangement being then such that the connecting point F can be xed in said slot after it has been shifted therein. If the active length E-F is re-adjusted, then the length of way on which the circular arc described by the point F can be regarded as corresponding with a certain portion of the closed curve will be correspondingly longer or shorter so that it is rendered possible to vary the duration of the periods of standstill. To sum up, it may be said that the following rte-adjustments are of particularly practical importance:

(a) Variation of the position of the point E in the coupling plane, or

(b) Variation of the length of the rod or link E-F, or

(c) Simultaneous variations according to (a) and (b).

Owing to these three possibilities of adjustment, the duration and the position of the individual periods of motion and of standstill may be varied in any desired manner, and besides there remains the possibility of obtaining further re-adjustments by varying the length of any one or of several of the members of the articulated quadrilateral. Such other re-adjustments can be carried out especially in'suclr cases in which the other possibilities, as mentioned under (a), (b) and (c) cannot be made use of for any reasons. Thus, by adjusting or re-adjusting the several members in the manners stated a gearing can be produced, the periods of standstill of which may be adjusted or re-adjusted just as required, and also the times at which the standstills take place relatively to the times of motion may be determined at will.

If two or more periods of standstill are required during one comple oscillation, coupling points are used that produce curves so shaped that they may be replaced at two or more places by circular arcs of the same radius. A constructional form of such a gearing is shown in Fig. 2. In this figure A1, Bi, Ci, Di denote the articulated gearing, and E: denotes the coupling point. curve which this point describes has two portions, viz, E3E4 and Eff-Es, for which circular arcs of the same radius can be substituted. The length Ez-Fz is equal to the length of that radius. The point Fa is also in this case connected with the stationary point G2, for instance by a rod or link lib-G2. With this constructional form the point Fu will come to a standstill while the point E: is passing through the curve portion Es-E4, as well as while it is passing through the curve portion Fs-Es.

Not in all cases will it be indispensably necessary to employ exactly the radius of curvature at the respective place or point of the coupling curve for the length of the rod or link E-F, or Es-Fz respectively. Departing therefrom a little upwardly or downwardly, this will cause a corresponding lengthening or shortening of the period or standstill. The position of rest will, theoretically, not oe accurate, it is true, but, nevertheless,it will be approximately correct and this will practically suice in many cases, or even be preferred. Ii that departure is somewhat great, there may result a shaking motion which can be produced intentionally and can be vutilized for The 1 certain technical purposes. Also in such cases the approximate length of the period of standstill may be so determined as to be in accordance with certain prescribed values, and may also be adjustable.

The considerations submitted in the rst part of this specification show that the gearing is not limited to the employment of articulated quadrilaterals. The phenomena dealt with are met with in any other moved rod, and it is, therefore, possible to make use, instead of the rod or link B-C, of any other moved rod and to connect this rod with a suitably chosen point, which, then, does not describe a coupling curve, but any other curve that constitutes its path. Especially, a point of a gearing of a machine, either an already existing one or one still in course of construction or building, that is to say, of a gearing, the movements of which are known, can be used as the starting point from which the periods of standstill are to be derived.

If the problem is to produce in a machine a plurality of movements with intercalated periods of standstill, all those movements can be derived from the same coupling plane of an articulated quadrilateral or from the corresponding rod plane or any other gearing, in that only corresponding points'of the coupling plane or of the rod plane with the appertaining path curves are used. It is, thus, by no means necessary to design a separate gearing for every separate or particular movement. It is possible to choose, besides the points E, with the aid of .which motions with intercalated periods of standstill are produced, also such other points in the same rod plane by which ordinarilyv motions without periods of standstill are produced. This entails great simplications, especially in the design and construction of automatic machines. Also great savings are obtained when the respective machines are mounted and adjusted, in that the respective gearings allow of a very great re-adjustability and can, thus, be accommodated to all practical requirements.

As has already been mentioned, the point F can be guided in any desired manner, according to the motion to be produced. A particular manner of guiding would be, for instance, that wherein the point G itself with which the point F is connected by the rod or link F-G would be moved. This rodfor link would perform in that case a movement in that during a certain prescribed time it would make a revolution around a temporarily stationary point F. But also the point G might be moved in a similar manner, that is to say, also this point might be driven by a point of the same rod plane or of another rod plane, the corresponding rod or link being again equal to the radius of curvature of the path curve of the point G withina certain range. In this case also the point G will perform a movement with intercalated periods of standstill. According as these periods coincide with those of the point F, or do not coincide with them, the rod F-G will for a certain period of time remain completely stationary, or will turn, in alternation with that period, around the stationarypoint F or the stationary point G.

Figs. 3 to 5 inclusive show the invention illustrated in the diagrammatic Figs. 1 and 2, as embodied in an actual mechanical movement which may be used for any desired purpose. In this constructional form, illustrated merely by Way of example, a designates a slide guided in a groove in the element b. To this slide a is secured a stud or pivot F, to which is pivoted a short link q. The other end of the link q is pivotally attached to a shaft or stud E, which is pivotally connected to one end of an L-shaped lever designated generally by the letter p. This L-shaped bar or link is guided pivotally by two other links, namely a link u pivoted at D to a stationary part of the mechanism, and pivoted at C to a point of the lever p, here shown as the angle or bend of said L-shaped lever. The other end of the L-shaped lever is pivotally connected as shown, to the crank pin or the like, B, which is carried by a crank n mounted upon a shaft A which is rotated to produce motion of the mechanism. Here the link q, whose length is E F, is of substantially the same length as the radius of curvature of a portion of the locus of the point E, so that during said part of the locus the slide a will remain substantially at rest, just as does the corresponding point F of Fig. 1. Fig.- 5 illustrates the said motion of the slide a in rectangular co-ordinates. The circle in which the center of the crank pin B moves is divided into twentyfour parts in Fig. 3, and these same parts are plotted as abscissas in Fig. 5, with the corresponding linear displacements of the slide a as ordinates. The slide a will be at its extreme right hand position at the point a0 of Fig. 5, corresponding to a position between 1 and 2 of the circle, will gradually move to the left till it reaches position bo, corresponding to position 9 of the circle, will then have a dwell or rest till c0 is reached, corresponding to position 12 of the circle, will proceed again through d0, to its maximum displacement e0 at position 19 and will then return to its initial position at a0.

I wish it to be understood that I do not limit myself merely to the details of the gearings described in the preceding pages, but many departures in the details are possible without departing from the subject matter of this invention.

I claimz- 1. A mechanical movement comprising a series of links pivoted to one another by means of more than three pivots, drive means for moving one of said links, whereby any point of said link will describe a locus peculiar thereto, a driven element, means pivotally vconnecting said driven element to a selected point of the said link, the said connecting means being of a length-substantially equal to the radius of curvature of a portion of the locus to thereby produce interposed periods of standstill, and means for guiding the driven element in a denite path.

2. A mechanical movement comprising a series of links pivoted to one another, drive means for moving one of saidlinks, a member rigidly secured to one of the links so as to partake of the motion thereof, whereby any lpoint of said member will describe a locus peculiar thereto, a driven element, means pivotally connecting said drivenI element vto a selected point of the said member, the said connecting means being of a length substantially equal to the radius of curvature of a portion of the locus to thereby produce interposed periods of standstill, and means for guiding the driven element in a definite path.

3. A mechanical movement comprising a series of links pivoted to one another, drive means for moving one of said links, whereby any point of said link will describe a locus peculiar thereto, a driven element, means pivotally connectingrsaid driven element to a selected point of the said link, to provide a locus having several separate portions of substantially the same curvature, the i lill] said connecting means being of a length substantially equal to the common radius of curvature of said separate portions of the locus to thereby produce interposed periods of standstill,

moving one of said links, a member rigidly secured to one of the links so as to partake of the motion thereof, and not in a straight line with said link, whereby any point of said member will describe a locus peculiar thereto, a driven element, means pivotally connecting said driven element to a selected point of the said member, the said connecting means being of a length substantially equal to the radius of curvature of a portion of the locus to thereby produce interposed periods of standstill, and means for guiding the driven element in a denite path.

HERMANN ALT.

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