US2393305A

US2393305A - Centrifugal pendulum

Info

Publication number: US2393305A
Application number: US510704A
Authority: US
Inventors: Birkigt Louis
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-04-07
Filing date: 1943-11-17
Publication date: 1946-01-22
Anticipated expiration: 1963-01-22
Also published as: BE453950A; GB577803A; CH251485A; GB604219A

Description

Patented Jan. 22, 1946 cEN'rRnUGAL PENDLUM 'e Louis Birkigt, Versoix,. nearl Geneva, Switzerland, assigner to Gilles Franois Sarazin, Saint-Prix` (Seine-et-.Ose`), France ApplcationfNovemherl', 1943, Serial No. 510,704 t In France April 7, 1943. e

22 Claims.

The-'present invention. relates to centrifugal= tion and tends, through its: reactions on the ro` tating part `uponlwhich it is mounted, to'opposethev perturbing displacementswhich would otherwisebeimparted to said rotating part as: a'result of this vibration;

It has already been proposed to make centrifugal pendulums in thev form of bilar pendulurns, in order tolavoid their oscillationproducing' a rotation .of Athe pendular mass about its center of gravityyand to havetheir frequency independent of the magnitude'of said mass. f

In the French Patents No. '724,234 and No. 783,734 and the French addition Patent No. 41,251 various solutions jhave been described for the suspension of the rpendular mass, through links either real or fictitious. v

The object ofthe present invention is to provide a centrifugal pendulum of the type above` stated which' is suspendedL in a manner better adapted tofmeet the Vrequirements of practice Y than'it was the-:case with the prior apparatus.

for suspending the pendularfmass are arranged in such manner that a given increase ofzthe centrifugal force due to the rotation of the rotating ypart uponwhich' the pendulum is mounted pro-l duces an' increase of the lengthof the theoretical pendulum equivalent to thev centrifugal vpendui Y lum that is being considered.

, Other features of the present invention will result from the following detailed description of some specic embodiments thereof. r f

Preferred embodiments of the present inven'- tion willbe'hereinafter described, with reference to the accompanying drawings, given merely by way of example, and in which: l, Fig. lA is .a diagrammaticalrviewin elevation of a centrifugal pendulum made according to the invention; y Y

lig..V 2 is a sectionalview on the line IIe-Il?v of Figli 'f Fig. 3 isr a'sectional view on a.v larger scale of a centrifugal pendulum made according to one embodiment of the invention;

Fig. L is a view, corresponding to Fig. 3,--partly in sectional view on the line IV`IV of Fig. 3 and partly in elevational view; Y

`Fig. 5 shows anotherembodiment of the invention,v being a sectional View on thev line V-fV ofFig. 6;' f Y e Fig.: 61 is a sectional view on the line VI-VIof Fig.5-; Y.

Fig. 'Z is a perspective view ofthe 4centrifugal pendulum of Figs.5 and 6;

4li'g. 8 is a perspectiveV view `of some elements of this pendulum prior to their assembly; y

Fig; 9 is a diagrammatical view of a pendulum made, according to th'e invention, in suchy manner that its pendular length can increase in accordance with thefcentrifugal force.

In thev following description, it will `be supposedy that it is desired to provide a bifllar centrifugal pendulum intended for instance for a torsional vibration damper for a driving shaft I. f

. This shaft- I is provided with a plate or disc r2 and this disc is connected to a pendular mass 3 through` at least two flexible links 4, each of which is applied at its ends on convex surfaces Sand E belonging respectively to' massff3 and Ydisc 2. y

These

surfaces

5 and 6 are arrangedin such manner that the links #remain always tangent thereto during the whole of the pendular oscillation, the maximum amplitude f which isA 2A.

Preferably, these surfaces are given the shape of ,equal surfacesof revolution about axes Band C, respectively fixed with respect to the pendular mass and to the disc carried by shaft l.

According to the invention, which is diagrammaticallyillustrated by Figs-1 and 2, raxes B and C are common lto thesurfaces that cooperate with the-right andA left flexible links of the rbifllar sus.-

pension. The surfaces 5 that belong to the pen- 'dular mass may then be given the shape of a complete surface of revolution, andtheY surfaces 6 that belong to disc 2 are given an identical shape. In this case links 4 can consist of loops passing around said surfaces, in a manner analogous to that of albeit passing around twopulleys of equal diameters. f f l It will be readily understood that,with such an arrangement, when mass 3 is given a pendular oscillatory movement, it remains constantly parallel to itself. In otherwords, the `movement it undergoes isof the translatory kind. l I

Links .4 caribe constitutedby wires or thin i bands, for instance of textile material (natural or artificial silk) or of metal either inthe form of wires orof steel or .other metal ribbons Mofa will be chosen in accordance with the natural period that the pendulum to obtain is to have for each revolution of shaft I.

Of course, links 4, instead of being in the form of complete loops, may be made each in the form of separate elements. The ends of these elements will then be fixed respectively to surfaces and 6 at points thereof such that, when the pendulum oscillates with the maximum amplitude 2A, said link elements still remain .tangentially applied against said surfaces.

I might also limit each of the surfaces in question to the arcs, corresponding to an angle 2A, along which, during the oscillation, moves the point of tangential contact of the link element with said surfaces.

I might also provide, for each link, centers B1, C1 and B2,C2 such that B1 and Bzon the one hand and C1 and C2 on the other hand do not coincide'. I n this case the distance from B1 to B2 must be equal to the distance from C1 to C2. Likewise, the distances from B1 to C1 and from B2 to C2 must be equal to each other and to the pendular length 1". y 'y A device embodying theserconditions is illustrated by'Figs, 3 and 4. y

If, as it is the case inthe arrangement shown by these figures, length r is smaller than the height of the arcs of surfaces 5 and B along which move the points of tangential contact'of links 4 therewith, these surfaces 5 and B are advantageously made as follows, as illustrated by said Figs. 3 and 4: They are given a comb-like structure, that is to say are-provided with teeth extending along the directrices of said surfaces and engagi-ng between one another with a certain play, For instance, a tooth or element 1 of one of the surfaces, say 5, passesl freely between two teeth or elements 8 of the other surface 6. In this case, the links will be given the shape of bands simultaneously in contact with portions of said teeth I and 8. Thus the pendular length r' can be made as small as it is desired with'reference to the common radius of surfaces 5 a-nd 5.

The fixation of bands 4 respectively to .the pendular mass 3 and the disc 2 carried by the shaft may, for instance, be obtained, as shown by Fig. 3, by means of screws such as 9 and Ill arranged to hold the ends of said bands 4 tightly against portions of

surfaces

5 and 6.

According to the embodiment illustrated by Figs.` 5 .to 8, the pendular mass is constituted by the superposition of three plates` which may for instance be obtained by merely cutting them by means of a press from steel plates. The two outer plates or discs, I9 and 2i), are made of the same thickness, a1, While the inner plate or disc 2l is made of a thicknessln substantially equal to two of ai. These three plates are suitably fixed together, for instance by means of rivets.

These plates or discs are given the general shape of semi-circles. But each of the outer plates I9 'and 20 is provided with projections at the respective ends of the diameter by which it is limited, thesek projections of the cylindrical periphery of the plate constituting the equivalent of the teeth 8 of the embodiment of Figs. 3 and 4. On the contrary, the inner plate 2I is bevelled at the ends of the diameter to which it is limited.

v'shaft' I for cooperating with the pendular mass thus formed is also made by the superposition of three plates similarto those above referred to, but which are preferably given slightly derent ,lthicknesses. For instance, if the teeth AIl are carried by the outer plates I9 and 20 of the pendular mass, the

outer plates

22 and 23 of the support Y will be made of a thickness ai greater than a1 by iii) some tenths of a millimeter, while the inner plate 24 of said support will be given a thickness b2 smaller than.b1 by some tenths of a millimeter.

In the embodiment illustrated by the drawings, inwhich the inner plate 2| of the pendular mass is bevelled at the ends of the diameter by which it is limited, lthe inner plate 24 of the support is provided, atV the ends of the diameter by which it is limited, with projections constituting the equivalent of teeth-1 of the embodiment of Figs. 3 and 4. 0n the contrary, the ends of the diameter edges of

plates

22 and 23 are bevelled so as to correspond tothe projections 8 of the plates I9 and 20 of the pendular mass. Thus, opposite each

tooth

1 or 8 there is provided a hollow space of corresponding width and shape, whereby, once thelinks 4 have been xed in position, for instance by fixation tothe middle plates 2I and 24, the pendular movement can take place freely.

The support constituted by the superposition of

plates

22, 23 and 24 can be xed through any suitable means to disc 2, for instance by means of the rivets 25 through which the plates in question are assembled together. Y

Whatever be the particular embodiment that is chosen, I obtain, according to the present invention, a bilar `centrifugal pendulum which is particularly simple and economic to manufacture. This pendulum is also very strong, owing to the fact that links 4, which are well guided by surfaces'Svand'G, are not subjected to important flections capable ofA breaking them.

vA centrifugal pendulum made as above described may also-involve the following feature, which may, in some cases, be used separately. According to this feature, the suspension means of thependular mass of the apparatus is ar.. ranged in such manner that agiven increase of the centrifugal force dueto the rotation of shaft I produces an increase ofthe pendular length r' of the pendulum.

For this purpose, in a construction of the type above described-for the obtainment of a bilar pendulum, I provide `each of the links 4 with an elastic system such that these links are given a' certain increase of length under the effect oiv a givenv increase of the centrifugal'force.

For instance, inzorder to obtain this result, instead ofxfxing these links in a rigid manner at both of their ends, they are elastically mounted at least at one of their ends, for instance that f which is secured to disc 2.

' An embodiment of such a device is shown by Fig. 9.

In this construction, one end, that located on the-side of disc 2, of each of the links 4 is xed to an arm II capable of pivoting about axis C through an angle D corresponding to an are of the surface B which lcoacts with the link 4 that isV being considered, said arc corresponding to angle D being located beyond the arc correspond ing to the maximum amplitude 2A.

" order to urge this-.arm Il vin 'the direction tending to shorten the-lengthef thecorrespon'tl- Y ing "link-4, there is -providedJa-spring |12 -of determined strength, whereby larm Il assumes `constantly lthe 4desired position under the opposed effects of spring l2 andthe pull exerted by .the centriiug-alforce-onlink 4. Advantageously, I synchronize the displacements of thek two armsv Il corresponding to ythe Samependulum, 'wherebyfboth of the links thereof are always of vthe same length. This `result is for instance obtained, as shown by Fig; 9, kby

Ameans foftwo rods I3 pivoted to each other about a vpin slidable in a symmetrically"V disposed slot.

Instead of leaving the :system 'thusrprovided free to work in such manner that, to every value of the centrifugal force, there -correspondsa well determined pendular length r', n it 'may be advantageous to provide means such that, when the centrifugal force gradually increases, the pendular length successively passes through given values f1, rz, r'a and stays at each Iof these values for a predetermined zone of vvariation of the centrifugal force. A, v v

` With this object in View, vfor instance, I x v(in the spindle of lever II a discV 'I4 vthefperiphe'ry'of which is provided with suitably located notches I5, while a resiliently locking member yIt pushed by aspri-ng .|1, is adapted :to engage into that of said notches which is passing opposite it.

'It will be readily understood that if member I6 is, for instance, engaged inthe nrst of these "notchesl `(positionshown by Fig. 9)., it remains therein 'as long as the centrifugal -force has-not reached a value capableof driving member I 6' out from ysaid notch by causing it'to slide alongxthe inclined edge thereof. When the centrifugal lforce exceeds this value, disc VI4 and'lever Irl are Vsuddenly caused to pass tothe next position, for

If necessary, and vin order to render the adjust ment system more sensitive, means may fbe provided for reducing the lfriction resulting'from the displacement that takes place between .links 4 and the surfaces along which'said links wind and unwind, when thependular length varies and said surfaces are fixed.

For this purpose, `for instance, I may provide rollers I8 or the like between each link 4 and the surface which supports it. Alternately,-l'. might arrange said surfaces in such manner as to have them pivoting asa whole about axis C when lever Il itself pivots. 1 v .Y In a general manner, while I have, in the above description, disclosed whatI deem: to be practical and ellicient embodiments of .my invention, it should be well understood that I do notk wish to be limited thereto as there might be changes made in the arrangement, disposition and'form of the parts without departing from the principle of the present invention as comprehended within lthe scope of the appended-claims. v

AWhat I claim vis :v

1; In combination with rotating means, 4a dynamlc vibration rhunpingl .device including a pendulum which comprises in combination, a supporting part, la `'penvzlular mass, at least v.two corresponding surfaces, one rigid with said supporting part and the other rigid with lsaid pendular mass, and twoflexiblelinks each secured at` one end to saidsupporting part and .atl the other-fend to said Ipendular mass so as each to pass around said two Asurfaces and to wind on one while .simultaneously unwinding from the other during pendular oscillation.

In' combination with rotating means, .a dynamicvibration damping device including a pendulum 'which comprises, `in combination, la

supporting part, a pendular mass, two pairs of Vcorresponding surfaces, each pair consisting of 'a surface rigid with said Vsupporting partand an equal surface rigidwith said pendular mass,'these two last mentioned surfaces being of revolution .about respective axes iixed to' Vsaid supporting vpart i and Vto :saidfmasa respectively, and'two flexible links each secured lat one end to `said supporting part. .and attheother end to said vpendular mass soY as each to pass aroundthe two surfaces of one pair and to windV on one of said two surfaces while simultaneously unwinding 'from the other during pendular oscillation.v i

3. In combination with rotating means, a dynamic vibration vdamping device including Aa pendulum which comprises, in combination, a supporting part, a pendular mass. two pairs of rvcorresponding surfacesyeach pairA consisting of a surface rigid `with said supporting part and a corresponding surface rigid with said pendular mass, the surfaces `rigid with the supporting part being elements of a surface of revolution about an axis'r fixed with. respect to said part, and the surfaces rigid with the pendular mass being equal elements of a surface of revolution about an axis .fixed with'respect to said mass, and -two flexible links each secured at one end to said supporting part and at the other yenduto said pendular mass soas each to pass around the two surfaces of" one pair land to winden oneof said .two surfaces while simultaneouslyv unwinding from the other during pendular oscillation.

4.. In combination with rotating Vmeans, a dynamic vibration damping device including a .pendulum which comprises,l in combination,

a supporting part, a pendular mass, two identical sur- Faces fof 4revolution one rigid with said supporting` partand the other rigid with said kpendular' mass, andilexiblemeans connecting said supporting part and said pendular mass in spaced relationship and disposed so as to pass around the two surfacesv and to wind on one While simultaneously unwinding from the other during pendular oscillation. Y

5. In combination with rotating means," a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, at least two corresponding surfacesone rigid with said vsupporting ,part and the. other rigid with said pendular mass, and two flexible elements each secured at one end to said supporting part Aand at the other end to said pendular mass so. as each to .pass aroundl the two surfaces and to wind on one .while simultaneously unwinding from the other during pendular oscillation. y I

6. In combination with rotating means, a dynamic Vvibration damping device including a pendulum whichV comprises, in combination, a supporting part, a pendular atl `least -two corresponding surfaces, one rigid v,with said supporting part and the other rigid with'said pendular mass, and two flexible bands each sependulum which comprisesin combination, a

supporting part, a pendular mass, at least two corresponding surfaces one rigid with said supporting part and the other rigidwith said pendular mass, and two flexible links each secured at one end to said supporting part and at the other end to said pendular mass so as each to pass around said two surfaces and to wind on one while simultaneously unwinding from the other during pendular oscillation, said links being respectively secured to said surfaces at points such that, for the maximum amplitude of oscillation, the links remain tangent to said surfaces.

8. In combination with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, two pairs of corresponding surfaces, each pair consisting of a surface rigid with said supporting part and a corresponding surface rigid with said pendular mass, and two flexible links each secured'at one end to said supporting part and at the other end to said pendular mass so as each to pass around the two surfaces of one pair and to wind on one of said surfaces while simultaneously unwinding from the other during pendular oscillation, each surface being limited to the portion along which moves the point of tangencyof the corresponding link thereon, for the maximum amplitude of oscillation.

9.,In combination with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, two pairs of ycorresponding surfaces, each pair consisting Y of a surface rigid with said supporting part and an equal surface rigid with said pendular mass, these two last mentioned surfaces being of revolution about respective axes fixed to said supporting part and to said mass, respectively, the disi tance between the axes of the surfaces rigid with the vsupporting part being equal to the distance between the axes of the surfaces rigid with the pendular mass, and two flexible links each secured at one end to said supporting part and at the other end 'to said pendular mass so as each to pass around the two surfaces of one pair and to wind on one of vsaidtwo surfaces while simultaneously unwinding from the other during pendular oscillation. l x

l0. In vcombination with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, two pairs of corresponding surfaces, each pair consisting of a surface rigid `with said supporting part and a corresponding surface rigid with said pendular mass, and two flexible links each secured at one end to said supporting part and at the other end to said pendular mass so as each to pass around the two surfaces of one pair and to windI on one of said surfaces while simultaneously unwinding from thev other during pendular oscillation, said surfaces being of comb-like structure, so that the teeth of one of themV engage freely between the .teeth of the corresponding one.

11,. In combination `with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part constituted by a plate the edge of which is of circular shape, extending over more than one semi-circle, a pendular mass constituted by a plate parallel to the rst mentioned plate and the edge of which is of circularshape, extending over more than onesemi-circle of the same diameter as the first mentioned one, and two flexible bands each secured at one end to the circular edge of one Aofsaid plates and at the other end. to the circular edge of the other plate so that each band is tangent to the edges of the two plates in suchrmanneras to wind on one of said edges whileA simultaneously unwinding from the other during pendular oscillation.

12. In combination with rotating means,v a dynamic vibration damping device including a pendulum which comprises, in combination, a 'part formed by three semi-circular discs assembled together side by side, the two outer discs including projections beyond the diameters that limit them so that their peripheries cover more than one semi-circle and the inner disc being bevelled at its ends so that its periphery covers less than one semi-circle, another part made of three semi-circular discs of the same diameter as the first mentioned discs assembled together side vby side, the two outer discs ybeing bevelled and the inner one provided .with projections, one of said composite parts forming the supporting part of the pendulum and the other the pendular mass, and atleast one flexible band each secured both 'to the'circular edge of one of said parts and to the circular edge of the other part, so as to wind on one of said edges while unwinding from the other during the pendular movement, the thicknesses of said discs 'being so chosen that the projectionsof` one disc can move freely in the spaces vcorresponding 'to the bevelled portions of the corresponding disc of the other part.

13. Inl combination with rotating means, a dynamic vibrationV damping device including a pendulum which comprises, in combination, a part formed by three semi-.circular discs assembled` together side by side, the two outer dises including projections beyond the diameters that limit them so that their peripheries cover more than one semi-circle and the inner disc being bevelled'at its ends so that its periphery covers less than one semi-circle, another part made of three semi-circular discsof the same diameter as theV rst mentionedr discs assembled together side by side, the two outer discs being bevelled and the inner one' provided with projections, one of said composite parts forming the'supporting part'of the pendulum and the other the pendular mass, and'two nexible bands each secured at one end to the circular edge of one of said parts and 'at thefother end to the circular edge of the other part, so -as to wind on one of said edges while unwinding from the other during f the pendular movement,'the thicknesses of said' discsbeing so chosen that the projections'of one disc can-move freely in the spaces corresponding to the bevelled portions of the corresponding'disc of the other `Part.

Y114. Incombination with rotating means,` a dynamic vibration damping device including' a -pendulum which comprises; in combination, a

part formed by three semi-circular discs assembled together side by side,`- :the'ztwo outer discs including projections beyond the diameters that limit them so that their peripheries cover more than one semi-circle and the inner disc being bevelled at its ends so that its periphery covers less than one semi-circle, another part made of three semi-circular discs of thesame diameter as the rst mentioned discs assembled together side by side, the two outer discs being bevelled and the inner one provided with projections, one of said composite parts forming the supporting part of the pendulum and the other the pendular mass, and two flexible bands each secured at one end to the circular edge of one of said parts and at the other end to the circular edge `of the other part, so as to wind on one of said edges while unwinding from the other during the pendular movement, the thickness of each of the outer discs of the first mentioned composite part being smaller than that of the corresponding disc of the other part, while theV thickness of the inner disc of the first mentioned part is greater than that of the inner disc of the other part, whereby the projections of one disc can move freely in the spaces corresponding tothe bevelled portions of the corresponding disc of the other part.

15. In combination with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, at least two corresponding surfaces, one rigid with said supporting part-and the other rigid with said pendular mass, and two flexible links each secured at one end to said supporting part and at the other end to said pendular mass so as each to pass around said two surfaces and to wind on one while simultaneously unwinding from the other during pendular oscillation, said links being adapted to produce increase of the pendular` radius when the centrifugal force increases.

16. In combination with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, at least two corresponding surfaces one rigid with said supporting part and the other rigid with said pendular mass, and two flexible links each secured 'at one end to said supporting part and at the other end to said pendular mass so as each to pass around said two surfaces and to wind on one while simultaneously unwinding from the other during pendular oscillation, said links being elastically secured to at least one of the'two parts to which they are secured at their ends so as to produce an increase of the pendular radius in response to an increase of the centrifugal force.

17. In combination with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, at least two corresponding surfaces, one of circular shape rigid with said supporting part and the other with said pendular mass, and two exible links each secured at one end elastically to said supporting part and at the other end rigidly to said pendular mass so as to pass around said two surfaces and to wind around one while' simultaneously unwinding from the other during pendular oscillation, the elastic securing of at least one link to said supporting part consisting of an arm pivoted about the center of the circular-shaped surface of said supporting part, with means for xing the end of said link to the end of said arm,

pendulum which comprises, in combination, a

supporting part, a pendular mass, at least two corresponding surfaces, one of circular shape rigid With said supporting part and the other with said pendular mass, and two flexible links each secured at one end elastically to said supporting part and at the other end rigidly to said pendular mass so as to pass around said'two surfaces and to wind around one while simultaneously unwinding from the other during pendular oscillation, the elastic securing of at least one link to said supporting part consisting of an arm pivoted about the center of the circular-shaped surface of said supporting part, with means for fixing the end of said link to the end of said arm, elastic means for yieldingly opposing the rotation of said arm under the action of the centrifugal force, and means for resiliently locking the rotation of said arm in predetermined angular positions thereof.

20. In combination with rotating means, a dynamic vibration damping device including a pendulum which comprises, in combination, a supporting part, a pendular mass, at least two correspending surfaces one rigid with said supporting part and the other rigid with said pendular mass, and two flexible links each secured at one end to said supporting part and at the other end to said pendular mass so as each to pass around said two surfaces and to wind on one while simultaneously unwinding from the other during pendular oscillation, said links being elastically secured to at least one of the two parts to which they are secured at their ends so Y as to produce an increase of the pendular radius in response to an increase of the centrifugal force, and means for reducing friction between each link and the corresponding surface of the supporting part upon sliding of one on the other.

21. In combination with rotating means, a dynamic vibration damping device including a pendulumwhich comprises, in combination, a supporting part, a pendular mass, at least two correspondinglsurfaces, one rigid withv said supporting part and the other rigid with said pendular mass, and two flexible links each secured at one end to said supporting part and at the other end to said pendular mass so as each to pass around said two surfaces and to wind on one While simultaneously unwinding from the other during pendular oscillation, said links being l adapted to produce increase yof the pendular ra- LOUIS BIRK'IGT.