Abstract:
A method for assembling a pendulum-type damping device ( 1 ) includes the steps of force-fitting a first end of the spacer ( 17 ) into an opening ( 26 ) of a first part ( 3   a ) of a pendulum mass ( 3 ). A support ( 2 ) is positioned so that the spacer ( 17 ) spans a corresponding opening of the support ( 2 ). A roller is positioned between the spacer ( 17 ) and the edge of the opening of the support ( 2 ). The second end ( 17   b ) of the spacer ( 17 ) is force fit into an opening ( 26 ) of a second part ( 3   b ) of the mass ( 3 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY 
     This application claims priority to Patent Application No. 1358154 filed in France on Aug. 23, 2013 of which disclosure is incorporated herein by reference and to which priority is claimed. 
     FIELD OF THE INVENTION 
     The invention relates to a method for assembling a pendulum-type damping device and a damping device assembled in accordance with the method. 
     BACKGROUND OF THE INVENTION 
     A device of this kind, also called a “pendulum oscillator” or “pendulum,” is intended in particular to be part of a transmission of a motor vehicle. 
     In a motor vehicle transmission, at least one torsion damping system is usually combined with a clutch capable of selectively connecting the engine to the gearbox. 
     A combustion engine exhibits irregularities due to the successive combustion events in the engine&#39;s cylinders, said irregularities varying in particular depending on the number of cylinders. 
     The damping system conventionally has springs and friction elements whose function is to filter vibrations due to rotational irregularities of the engine, and takes effect before engine torque is transmitted to the gearbox. This allows such vibrations to be prevented from entering the gearbox and causing shocks, noise, and undesirable acoustic impacts therein. 
     In order to improve filtration further, it is known to use a pendulum-type damping device in addition to the usual damping device. 
     The Applicant&#39;s patent application FR 2981714 discloses a pendulum-type damping device having an annular support intended to be rotationally driven around its axis, and pendulum masses mounted on the outer periphery of the support. Each mass has a pendulum motion imparted to it during operation, and has two parts mounted axially on either side of the support and connected by two spacers each spanning an opening of the support. A roller is mounted between a rolling track configured in each spacer and the edge of the corresponding opening of the support. 
     In reaction to rotational irregularities, each mass shifts so that its center of mass oscillates in pendulum fashion. The oscillation frequency of each mass is proportional to the rotation speed of the driving shaft; the corresponding multiple can assume, for example, a value close to the predominant harmonic order of the vibrations responsible for strong rotational inconsistencies at close to idle speed. 
     The spacers are fastened to the two parts of the mass by riveting. The heads of the rivets abut against the outer radial faces of the parts of the mass, i.e. against the faces opposite to the annular support, and thus protrude axially from said parts of the mass. The volume thereby swept out during operation is relatively large, so that surrounding parts need to be dimensioned accordingly. 
     The load-bearing section of the rivet is essentially weaker than the total cross section of the part to be connected, thus weaker than the force-fitted spacer. The shapes of the spacer are simpler and thus easier to manufacture. 
     SUMMARY OF THE INVENTION 
     The invention aims to overcome this disadvantage by proposing for this purpose a method for assembling a pendulum-type damping device having at least one pendulum mass mounted movably on a support, said mass having two parts disposed on either side of the support and connected by at least one spacer spanning an opening of the support, a roller being disposed between the spacer and the edge of said opening, wherein it has the steps of:
         (a) force-fitting a first end of the spacer into an opening of said first part;   (b) positioning the support so that the spacer spans the corresponding opening of the support;   (c) positioning the roller between the spacer and the edge of the opening of the support;   (d) force-fitting a second end of the spacer into an opening of a second part of the mass.       

     Force-fitting of each end of the spacer into an opening of one of the parts of the mass allows the overall dimensions of the mass to be reduced. Specifically, it is not necessary for the ends of the spacer to extend axially out of said openings. 
     The ends of the spacer are preferably fitted in such a way that they are flush with the outer surfaces of the parts of the masses, i.e. the surfaces opposite the support. 
     According to a characteristic of the invention, at least one of the ends of the spacer is then welded to the part of the mass. 
     According to a characteristic of the invention the spacer is positioned, with respect to the first part of the mass and/or with respect to the second part of the mass, with the aid of guidance studs. 
     This ensures proper positioning of the two parts of the mass and the spacer throughout assembly. 
     In particular, each part of the mass can be guided with respect to a first frame with the aid of at least one first guidance stud projecting from the first frame. 
     In addition, the first end of the spacer can be guided with respect to the first frame with the aid of at least one second guidance stud projecting from the first frame. 
     The second end of the spacer can furthermore be guided with respect to a second frame with the aid of at least one third guidance stud projecting from the second frame. 
     In this case the ends of the spacer can be force-fitted into the corresponding openings of the parts of the mass by bringing together the first and second frames abutting respectively against the first part and the second part of the mass. 
     Each frame thus comes into abutment against one of the parts of the mass so as to ensure fitting of the ends of the spacer into the openings of said parts. 
     According to another characteristic of the invention, the second guidance stud and/or the third guidance stud span the opening of the corresponding part of the mass during steps (a) and (d). 
     Preferably each part of the mass has a radially inner edge and a radially outer edge, the first frame having three first guidance studs, two of which are received in complementary receptacles of the radially inner edge of each part of the mass and one of which is received in a complementary receptacle of the radially outer edge of each part of the mass, or vice versa. 
     Each part of the mass is thus held in position on the first frame with the aid of the first guidance studs. 
     In addition, the spacer can have a radially inner edge and a radially outer edge, the first frame and second frame respectively having three second guidance studs and three third guidance studs, two of which are received in complementary receptacles at the radially inner edge of each spacer and one of which is received in a complementary receptacle at the radially outer edge of the spacer, or vice versa. 
     Advantageously, each end of the spacer has a curved radially inner edge and/or a curved radially outer edge, so that each end flexes when it is force-fitted into the opening of the first part and/or second part of the mass. 
     Similarly, each part of the mass can have a deformable region situated radially inwardly from the opening serving for force-fitting of the spacer, said region deforming upon force-fitting of the corresponding end of the spacer. 
     Lastly, the spacer can be equipped with at least one stop intended to come into abutment against the edge of the opening of the support during operation, i.e. upon movement of the masses with respect to the support. 
     The invention also relates to a pendulum-type damping device having at least one pendulum mass mounted movably on a support intended to be rotationally driven, said mass having two parts disposed on either side of the support and connected by at least one spacer spanning an opening of the support, a roller being disposed between the spacer and the edge of said opening, wherein the ends of the spacer are fastened to the two parts of the mass by force-fitting. 
     Preferably the ends of the spacer are flush with the outer surfaces of the parts of the masses, i.e. the surfaces opposite the support. 
     At least one of the ends of the spacer is also fastened to the part of the mass by welding in addition to force-fitting. In this case provision can be made to fit the end of the spacer to a depth just sufficient to hold the spacer in place on the part of the mass, then a weld is made at the joining point between the spacer and the part of the mass. 
     Preferably the end of the spacer is fitted so as to be flush with a face of the mass that is opposite another face of the same mass through which the spacer is introduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood, and other details, advantages, and characteristics of the invention will emerge, from the description below provided as a non-limiting example referring to the attached drawings, in which: 
         FIG. 1  is a perspective view of a pendulum-type damping device according to the invention; 
         FIG. 2  is a frontal view of a part of the device of  FIG. 1 ; 
         FIGS. 3 through 12  are views illustrating different successive steps of the method for assembling the device of  FIGS. 1 and 2  in accordance with the invention; 
         FIG. 13  is a frontal view of an end of a spacer, schematically illustrating the deformation of the latter upon force-fitting thereof; 
         FIG. 14  is a frontal view schematically illustrating the deformation of a part of the mass upon fitting of the spacer into the corresponding opening; 
         FIGS. 15 through 17  are frontal views illustrating three variants of the fitting of the spacer into a part of the mass; 
         FIGS. 18 and 19  are axial sectioned views of a part of a spacer and of a mass, illustrating two variant embodiments; 
         FIG. 20  is a perspective view of a spacer equipped with stop means according to a first embodiment; 
         FIGS. 21 and 22  are perspective views illustrating assembly of the spacer and of the stop means of  FIG. 20  onto the two parts of a mass; 
         FIG. 23  is a frontal view of a spacer equipped with stop means according to a second embodiment; 
         FIG. 24  is a perspective view of the assemblage of  FIG. 23 ; 
         FIGS. 25 and 26  are views that correspond respectively to  FIGS. 23 and 24  and illustrate a spacer equipped with stop means according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a pendulum-type damping device  1  according to the invention, having an annular support  2  on which masses  3  are movably mounted. 
     Annular support  2  has an inner annular part  4  connected to an outer annular part  5  by radially extending tabs  6 . The plane of inner annular part  4  is offset axially from that of outer annular part  5 . 
     The inner cylindrical surface of inner annular part  4  has an annular channel  7  opening radially inward. Inner annular part  4  furthermore has radial holes  9  opening into channel  7 . Lastly, inner annular part  4  has planar regions  10  at which radial holes  9  terminate. The channel receives a circlip that functions as an axial and angular stop. Each radial tab  6  has three holes  11  serving for the passage of rivets for fastening to a system for driving springs of the main damper. 
     In addition, outer annular part  5  of support  2  has six pairs of openings  12  ( FIG. 4 ). Each opening  12  has the general shape of an isosceles triangle whose vertices are rounded and whose base  13  is located radially inwardly. Vertex  14  opposite base  13  is curved, and forms a rolling track intended to interact with a roller  15 . 
     Semicircular recesses  16  are furthermore configured at the outer periphery of outer annular part  5 . More specifically, each recess  16  is situated circumferentially between the two openings  12  of a single pair. 
     Six masses  3  are mounted on outer annular part  5  of support  2 . Each mass  3  has a first part  3   a  and a second part  3   b  disposed axially on either side of support  2 , facing one another. The two parts  3   a ,  3   b  are connected to one another via two spacers  17 . 
     Each part  3   a ,  3   b  of mass  3  has a so-called “inner” radial face  18  ( FIG. 3 ) facing toward support  2 , and an outer radial face  19  ( FIG. 1 ) opposite to inner radial face  18 . In addition, each part  3   a ,  3   b  is in the shape of a circular arc and has a curved radially inner peripheral edge  20  and a curved radially outer peripheral edge  21 , connected by radial lateral edges  22 . Outer peripheral edge  21  has a semicircular recess  23  situated opposite one of the recesses  16  of outer annular part  5  of support  2  when mass is in the position depicted in  FIG. 1  (assembly position or initial position). 
     Inner peripheral edge  20  of each part has cutouts  24  at its circumferential ends. A semicircular recess  25  is moreover configured at each cutout  24 . 
     Lastly, each part  3   a ,  3   b  exhibits two openings  26  intended for assembly of spacers  17  by force-fitting. Each opening  26  is oblong in shape and has a globally rectilinear radially inner edge  27  and an arc-shaped radially outer edge  28 , connected by two rectilinear lateral edges  29 . The connecting regions between lateral edges  29  on the one hand and radially inner  27  and outer edges  28  on the other hand, are rounded. Radially outer edge  28  exhibits a rounded recess  30  in the middle part. Recess  30  also serves to detect the presence of the roller once assembly is complete. 
     Each spacer has a globally constant cross section over its entire length. More particularly, each spacer has a curved inner peripheral edge  31  and a curved outer peripheral edge  32  (see especially  FIG. 2 ). Outer peripheral edge  32  is concave and forms a rolling track for the corresponding roller  15 . Inner peripheral edge  31 , convex in shape, has two rounded recesses  33  at its circumferential ends. Each spacer  17  thus has, in a frontal view, two rounded lateral horns  34  at its outer peripheral edge  32  that become received in the two radially outer connecting regions  35  of the corresponding openings  26  (see especially  FIG. 2 ). The rounded shapes of horns  34  and of said connecting regions  35  are globally complementary. In addition, spaces  36  are formed by recesses  33  between spacer  17  and the edge of opening  26 . 
     The assembly of a pendulum-type damping device  1  of this kind, using a tool having a first frame  37  and a second frame  38 , will now be described. Each frame  37 ,  38  is annular in shape and extends substantially in a radial plane. 
     First frame  37  has six groups of three first guidance studs  39   a ,  39   b  and twelve groups of three second guidance studs  40   a ,  40   b  shorter in length than first studs  39   a ,  39   b.    
     Second frame  38  in turn has twelve groups of three third guidance studs  41   a ,  41   b . Third studs  41   a ,  41   b  have substantially the same length as second studs  40   a ,  40   b . All the guidance studs  39   a ,  39   b ,  40   a ,  40   b ,  41   a ,  41   b  are cylindrical, and their free ends can have chamfers. 
     During the assembly of pendulum-type damping device  1 , a first step consists in positioning first parts  3   a  of masses  3  on first frame  37  ( FIG. 3 ) so that outer faces  19  of parts  3   a ,  3   b  abut against face  42  of first frame  17 , studs  39   a  are engaged in recesses  25 , and studs  39   b  are engaged in recesses  23 . First part  3   a  is thus held in position by first guidance studs  39   a ,  39   b  and can only slide along them. 
     First ends  17   a  of spacers  17  are then positioned opposite openings  26  of first part  3   a . This positioning is facilitated by the fact that stud  40   b  comes into engagement in recess  30  and also comes into abutment against outer peripheral edge  32  of spacer  17 , and by the fact that studs  40   a  come into engagement in spaces  36  and come into abutment against spacer  17 . Spacer  17  is thus held in position by second guidance studs  40   a ,  40   b  and can only slide along them. 
     Support  2  is then placed so that one of the radial faces of radially outer annular part  5  abut against the so-called “inner” radial faces  18  of first parts  3   a  of masses  3  ( FIG. 4 ). During this step, stud  39   b  is engaged in recess  16  and studs  39   a  abut against edges  13  of openings  12 , more particularly at rounded vertices. Support  2  is thus held in position by first guidance studs  39   a ,  39   b  and can only slide along them. 
     Second parts  3   b  of masses  3  are then placed opposite first parts  3   a  so that studs  39   b  are engaged in recesses  23  of second parts  3   b , and so that studs  39   a  are engaged in recesses  25  of second parts  3   b  ( FIGS. 5 and 6 ). 
     Second frame  38  is then brought opposite first frame  37  ( FIG. 7 ). In the embodiment depicted in  FIGS. 6 to 12 , second frame  38  has a first annular plate  38   a  from which third guidance studs  41   a ,  41   b  extend, and a second annular plate  38   b  movable axially with respect to first annular plate  38   a . Second annular plate  38   b  has holes through which third guidance studs  41   a ,  41   b  pass, and holes through which first guidance studs  39   a ,  39   b  are intended to pass. 
     Second frame  38  is brought closer to first frame  37  until first guidance studs  39   a ,  39   b  pass through the corresponding holes of second plate  38   b . In this position, depicted in  FIG. 8 , the ends of third guidance studs  41   a  and  41   b  become inserted respectively into recesses  30  and into spaces  36  of second parts  3   b  of masses  3 . Third studs  41   a ,  41   b  are thus situated axially opposite second studs  40   a ,  40   b , and hold second end  17   b  of the spacer in position ( FIG. 8 ). The lengths of second studs  40   a ,  40   b  and third studs  41   a ,  41   b  are adapted accordingly, in particular allowing rollers  15  to be received between the ends of studs  40   b  and  41   b.    
     Second plate  38   b  is then lowered like a press so as to bring the two parts  3   a ,  3   b  of each mass  3  together, in order to force first ends  17   a  of spacers  17  to be introduced into openings  26  of first parts  3   a  of masses  3 , and second ends  17   b  of spacers  17  to be introduced into openings  26  of second parts  3   b  of masses  3  ( FIG. 9 ). This force-fitting requires deformation of each end  17   a ,  17   b  of spacer  17  and/or deformation of each part  3   a ,  3   b  of mass  6 , as will be described better below with reference to  FIGS. 13 and 14 . 
     Second plate  38   b  can then again be brought closer to first plate  38   a  ( FIG. 10 ), then the entire second frame  38  can be moved away from first frame  37  ( FIGS. 11 and 12 ) in order to release pendulum-type damping device  1  that has thus been assembled. 
     During force-fitting, first and second ends  17   a ,  17   b  of each spacer  17  can deform in response to the force exerted by the second plate.  FIG. 13  illustrates a cross section of one end of spacer  17  before force-fitting into the corresponding opening  26  (dashed line) and after force-fitting into opening  26  (solid line). The deformation has been deliberately exaggerated in this Figure. 
     In addition, during force-fitting, parts  3   a ,  3   b  of masses  3  can deform during force-fitting of the corresponding ends  17   a ,  17   b  of spacers  17 , in particular in the regions situated between radially inner edges  27  of openings  26  and radially inner edges  20  of parts  3   a ,  3   b .  FIG. 14  illustrates radially inner edge  27  of an opening  26  before force-fitting of spacer  17  (dashed line) and after force-fitting of spacer  17  (solid line). The deformation has been deliberately exaggerated in this Figure. 
     It is apparent that the shapes of spacers  17  and of openings  26  before assembly are adapted so as to produce the desired geometry after assembly, i.e. after deformation due to force-fitting. 
     As depicted in  FIG. 15 , the shapes of spacers  17  and of openings  26  can be such that after force-fitting, each end  17   a ,  17   b  of spacers  17  abuts against radially outer edge  28  of the corresponding opening  26  at lateral horns  34  of spacer  17  and at connecting regions  35  of opening  26 . 
     According to another embodiment depicted in  FIG. 16 , the shapes of spacers  17  and of openings  26  can be such that after force-fitting, each end  17   a ,  17   b  of spacers  17  abuts against radially outer edge  28  of the corresponding opening  26  at regions situated between lateral horns  34  and the middle region of radially outer edge  32  of spacer  17 . 
     According to yet another embodiment depicted in  FIG. 17 , the shapes of spacers  17  and of openings  26  can be such that after force-fitting, each end  17   a ,  17   b  of spacers  17  abuts against radially outer edge  28  of the corresponding opening  26  at the middle region of radially outer edge  32  of spacer  17 . In this case masses  3  have no recesses  30 . 
     In each of these embodiments, only the middle regions of radially inner edges  31  of spacers  17  abut against radially inner edges  27  of openings  26 . 
     Other embodiments are of course also possible. 
     In addition, as depicted in  FIGS. 18 and 19 , contour  44  of each opening  26  can be rounded or exhibit a chamfer at inner face  18  in order to facilitate insertion and fitting of the corresponding end  17   a  of spacer  17 . 
     The contour of end  17   a  of spacer  17  can likewise exhibit a chamfer  45  or a rounding so as to facilitate insertion or fitting thereof into the corresponding opening  26 . 
     The result is to limit contact pressures and to prevent chip formation or degradation of masses  3  during the assembly of pendulum-type damping device  1 . 
       FIGS. 20 to 22  show an embodiment in which each spacer  17  is equipped with two stops  46  made of elastomer. Each stop  46  extends axially and has two chamfered cylindrical ends  47  inserted into spaces  36 . Each stop  46  furthermore has a partly enlarged middle region  48  extending circumferentially beyond the corresponding horn  34  and inner edge  31 , capable of coming into abutment against the corresponding edge  12  of support  2 . 
     Note that stop  46  does not extend over the entire length of spacer  17 , so that spaces  36  situated axially on either side of each stop  46  still exist and permit insertion of the ends of studs  40   a  and  41   a  upon assembly of device  1 . 
       FIGS. 23 and 24  depict another embodiment in which each spacer  17  has a stop taking the shape of an elastomer strip  49  extending from one horn  34  to the other and running along radially inner side  31  of spacer  17 . Strip  49  is placed in the axially middle region of spacer  17  and has two domed ends  50  that snap into recesses  33  that are complementary in shape and placed below the horns in  FIG. 23 . In this embodiment, elastomer strip  49  can be produced independently of spacer  17  and then snapped into and/or fastened adhesively, for example, onto spacer  17 . 
     Note that as before, the reduced thickness (axial dimension) of elastomer strip  49  allows the retention of spaces  36  situated axially on either side of elastomer strip  49  for the purpose of inserting the ends of studs  40   a  and  41   a  upon assembly of device  1 . Studs  41   a  have a length greater than or less than the thickness of the mass, depending on geometry or on the presence of elastomer stops. The stops can furthermore be temporarily deformed by studs  41   a  during assembly, with no consequence for the product. 
       FIGS. 25 and 26  illustrate yet another embodiment of the invention, similar to that of  FIGS. 23 and 24  but differing from the latter in that ends  50  of strip  49  are not domed and snapped into recesses  33 . In this embodiment, elastomer strip is preferably overmolded onto spacer  17 . 
     Stops  46 ,  49  of this kind are intended to come into abutment against the edge of the corresponding opening  12  of support  2  in certain operating instances, in particular when the engine is being shut off or started, upon a gear change, and more generally in the event of jerking in the motor vehicle transmission. 
     After force-fitting, provision can also be made to perform welding of first ends  17   a  of spacers  17  at the join between first part  3   a  of mass  3  and second ends  17   b  of the same spacers. A weld of this kind allows a further improvement in the fastening of spacers  17  onto the two parts  3   a ,  3   b  of the masses. The welding will preferably be performed by laser. Welding of this kind can be considered for all the embodiments presented above.