Patent Publication Number: US-2012031226-A1

Title: Centrifugal force pendulum

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is filed under 35 U.S.C. §120 and §365(c) as a continuation of International Patent Application No. PCT/DE2010/000297 filed Mar. 18, 2010, which application claims priority from German Patent Application No. DE 10 2009 017 389.7 filed Apr. 14, 2009, which applications are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a centrifugal force pendulum. 
     BACKGROUND OF THE INVENTION 
     Centrifugal force pendulums of this kind are known, for example, from the published German Patent Application No. DE 10 2006 028 556 A1. This document describes a pendulum flange that is rotatable about an axis of rotation and may be part of a torsional vibration damper. The pendulum flange is provided with recesses on whose tracks rolling bodies roll. The rolling bodies roll in recesses of pendulum masses that are preferably arranged on both sides of the side surfaces of the pendulum flange, with two respective opposing pendulum flanges being connected to each other by connecting elements. The shape of the recesses in the pendulum flange and in the pendulum masses predetermines the deflection and the swinging angles of the pendulum masses relative to the pendulum flange. When torsional vibrations occur, the pendulum masses are deflected relative to the pendulum flange and act as a torsional vibration absorber due to their oscillating movement along a pendulum track. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a centrifugal force pendulum with improved ways of fixing the pendulum masses. 
     In accordance with the invention, a centrifugal force pendulum is arranged on a rotatable pendulum flange, for example, in the drive train of a motor vehicle. Pendulum masses, which can be moved to a limited extent in the radial direction and circumferential direction during the deflection thereof, are provided at the sides of the pendulum flange, for example, mutually opposing each other. Said opposing pendulum masses are fastened to each other by a connecting element, thus forming a pendulum mass pair. A bearing, which may advantageously be a rolling bearing or a journal bearing, is arranged on the connecting element. The bearing may also be a needle bearing, a roller bearing, or a ball bearing. This arrangement of the bearing on the connecting element is an improved way of attaching the pendulum masses to the pendulum flange. For instance, the number of required parts is reduced. 
     In accordance with one embodiment, the bearing rolls in the recess of the pendulum flange. An advantage of this attachment compared to the conventional way of fixing the pendulum masses is that lubrication between the rolling body and the track of the pendulum flange may be dispensed with. The centrifugal force in the rotating reference system of the pendulum flange causes a radially outward directed force to act on the bearing. Under these conditions, due to the mass inertia of the bearing, a torsional vibration of the pendulum flange causes a rolling movement in the recess of the pendulum flange. Due to the centrifugal force, this rolling movement occurs in the radially outward area of the recess on the rolling tracks. 
     Advantageously the connecting element to which the bearing and the pendulum masses are attached passes through the recess in the pendulum flange. Thus the pendulum masses are, for example, fixed to both sides of the connecting element and thus to both sides of the pendulum flange, for example, in complementary pairs. 
     In accordance with one embodiment, the shape of the recess in the pendulum flange defines the pendulum track of the pendulum mass, thus determining the movement of the pendulum mass with respect to the pendulum flange. For instance, due to the rolling movement of the bearing in the recess of the pendulum flange, the pendulum mass carries out a relative movement with respect to the pendulum flange. Consequently the recesses in the pendulum flange that are usually provided for the rolling movement of the rolling bodies can be dispensed with, thus increasing the mass of the pendulum mass and improving the absorbing effect of the centrifugal pendulum although the overall size remains the same. In addition, the pendulum mass does not require hardening, which would otherwise be necessary to increase its resistance to wear. Thus the manufacturing process is simplified. In particular, the shape of the recess can be used to influence the shape of the rolling movement of the bearing or of the pendulum mass relative to the pendulum flange. Moreover, the recess presents a limit to the rolling movement in the radial and circumferential directions. Thus the maximum angle of rotation of the pendulum mass relative to the pendulum flange can be predetermined 
     As viewed from a cross-sectional viewpoint of the pendulum flange, the shape of the recess is, for example, circular or semi-circular, the round region of the semicircle being advantageously arranged further outward than the straight region of the semicircle as viewed in the radial direction. The recess may also be kidney-shaped. An advantage of this shape is that at a transition from the rotating to the non-rotating pendulum flange, the bearing has a shorter fall in the recess as viewed in the radial direction. Thus the clunking sounds that may be created are reduced. 
     In accordance with one embodiment, the connecting element to which the bearing is attached is fixed to the pendulum mass by a rivet and/or screw connection or by an equivalent mechanical connection for fixing the connecting element to the pendulum mass. The connecting element itself may additionally act as a spacer pin and/or step-mounting pin of the pendulum masses arranged on both sides of the pendulum flange, thus potentially dispensing with separate spacer pins or step-mounting pins and further reducing the number of required parts. 
     In accordance with one embodiment of the invention, the centrifugal pendulum is included in a torsional vibration damper. The pendulum flange may be embodied as a functional part of the torsional vibration damper, for example as a damper flange or cover. 
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     Further advantages and advantageous embodiments of the invention will become apparent from the figures listed below and their descriptions. For reasons of clarity, the figures are not drawn to scale. 
       FIG. 1  is an elevational view of the recess of a centrifugal pendulum of the prior art; 
       FIG. 2  is an elevational view of one half of a centrifugal pendulum; 
       FIG. 3  is a cross-sectional view of the centrifugal pendulum of  FIG. 2  taken along the line  3 - 3  of  FIG. 2 ; 
       FIG. 4  is an elevational view of a pendulum flange with circular recesses; and 
       FIG. 5  is an elevational view of a pendulum flange with kidney-shaped recesses. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is an elevational view of a centrifugal pendulum  12  as it is known from the prior art. The centrifugal pendulum comprises a pendulum flange  12 . Pendulum masses  14  are fixed to the pendulum flange  12 . The pendulum masses  14  are movable to a limited extent and are preferably arranged in pairs of mutually opposing masses in the axial direction  50 . Movement of the pendulum masses is made possible by rolling bodies  16  that are guided in recesses  18  formed in the associated pendulum mass. Three spacer pins  20  are provided to fix the pendulum masses to the pendulum flange. In addition, axial contact elements  17 , preferably made of plastic, are arranged on the pendulum masses  14  to reduce the noise that occurs when the pendulum masses  14  contacts the pendulum flange  12  in the axial direction perpendicular to the plane of the drawing. 
       FIG. 2  is an elevational view of the centrifugal pendulum  10 . Connecting elements  22  are provided to fix the pendulum masses  14  to both sides of the pendulum flange  12 . Preferably two connecting elements  22  are provided for each pendulum mass  14 . The number of pendulum masses  14  may vary. 
     Due to this improved way of fixing the pendulum masses  14  to the pendulum flange  12 , the recesses  18  in the pendulum masses  14  and separate rolling bodies  16  may be dispensed with. Consequently, the pendulum mass  14  does not need to be hardened because it includes neither recesses  18  nor tracks for the rolling bodies  16 . Moreover, the volume of the pendulum mass  14  increases due to the elimination of the recesses  16  while the entire size of the device remains the same. This feature advantageously enhances the absorbing function of the centrifugal pendulum  10 . 
       FIG. 3  is a cross-sectional view of the centrifugal pendulum  10  along the line  3 - 3  shown in  FIG. 2 . The pendulum mass  14  is attached to the pendulum flange  12  by means of a connecting element  22 . A bearing  24 , in particular a rolling bearing or a journal bearing, is arranged on the connecting element  22 . The bearing may advantageously be located in a recess  34  of the pendulum flange  12 . In the rotating reference system of the pendulum flange  12  the centrifugal force creates a force acting in a radially outward direction on the pendulum mass  14 , the connecting element  22 , and thus on the bearing  24 . Under these conditions, a torsional vibration of the pendulum flange  12  may cause a rolling movement of the bearing  24  in the recess  34  of the pendulum flange  12  due to the mass inertia of the pendulum mass  14 . Due to the centrifugal force, this rolling movement takes place in the radially outer region of the recess  34  on the tracks  28 . 
     An advantage of this arrangement compared to the conventional way of fixing the pendulum masses  14  to the pendulum flange  12  is that no lubrication is necessary between the rolling body  16  and the track  28  of the pendulum flange  12 . The recess  34  and tracks  28  of the recess represent a limit to the rolling movement of the bearing  24  in the radial and circumferential directions. Advantageously, the connecting element  22 , to which the bearing  24  and the pendulum masses  14  are fixed, passes through the recess  34  in the pendulum flange  12 . The pendulum masses  14  are preferably arranged on both sides of the connecting element  22  and thus on both sides of the pendulum flange  12  in the axial direction, for example, arranged as a pendulum mass pair  32  formed by opposing pendulum masses. The connecting element  22  may, for example, be attached to the pendulum mass  14  by a rivet or screw connection  46  or a comparable method of attachment. The connecting element  22  is advantageously embodied as a spacer pin and/or step-mounting pin  30  to ensure secure fasting of the pendulum mass  14  to the connecting element. 
       FIGS. 4 and 5  represent a section of the pendulum flange  12  with two recesses  34  shown by way of example. The shape of the recess  36 , for example, defines the rolling movement of the bearing  24  fixed to the connecting element and in particular to the spacer pin  30 , thus defining the pendulum path of the connected pendulum mass (not illustrated in  FIG. 3 ) during the torsional vibration of the pendulum flange  12 . In one example, the cross-sectional shape of the recess  34  is circular  36  as shown in  FIG. 4 , thus causing the pendulum mass  14  to pass through a circular path on the track  28  relative to the pendulum flange  12  during the rolling movement of the bearing  24 . 
       FIG. 5  illustrates a further example in which the cross-section of the recess  34  is kidney-shaped  38 . Thus, the radial distance between the bearing  24  and the radially inner limiting surface  40  of the recess  34  is reduced, minimizing the radial drop of the bearing  24 . The result is a reduction of the noise that occurs when the centrifugal forces change spontaneously, for instance at a transition from the rotating to the non-rotating pendulum flange  12  and vice versa. 
     LIST OF REFERENCE NUMERALS 
       10  centrifugal pendulum 
       12  pendulum flange 
       14  pendulum mass 
       16  rolling body 
       17  contact element 
       18  recess in the pendulum mass 
       20  spacer pin 
       22  connecting element 
       24  bearing 
       28  track 
       30  spacer pin 
       32  pair of pendulum masses 
       34  recess 
       36  circular recess 
       38  kidney-shaped recess 
       40  radially inner limiting surface 
       50  axial direction