Abstract:
A centrifugal pendulum vibration absorber (CPVA) for absorbing torsional vibration created by operation of an engine includes a plurality of pendulums moveable with respect to a rotatable shaft. The pendulums are connected to the rotatable shaft by a plurality of pins that extend through apertures in the pendulum. The pendulums each move along a path defined by various drive line or powertrain parameters and characteristics. The path is implemented by contouring an active section of the apertures that engage the pins.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/299,757, filed on Jan. 29, 2010, which is hereby incorporated in its entirety herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a system for absorbing torsional vibration created by operation of an engine, and in particular to a system including a high performance centrifugal pendulum vibration absorber configured to absorb torsional vibrations created during engine operation. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0004]    Centrifugal Pendulum Vibration Absorbers (CPVAs) are typically used to reduce torsional vibrations in rotating machine components. For example, a rotating member such as a shaft includes several CPVAs, where each CPVA has a pendulum mass that oscillates as the shaft operates. The movement of the pendulum masses counteract torque fluctuations that are created as the shaft operates, which reduces the torsional vibration of the shaft. CPVAs can be designed such that the oscillation frequency of the pendulum mass matches the engine combustion frequency at any engine operating speed. The path of the center of mass of the pendulum has significant effect on the performance of a CPVA. Existing paths are typically circular or cycloidal. 
         [0005]    While current CPVAs achieve their intended purpose, there is room in the art to provide a CPVA having a pendulum mass path that is stable during rapid engine speed changes and that provides maximum vibration reduction. 
       SUMMARY 
       [0006]    A centrifugal pendulum vibration absorber (CPVA) for absorbing vibration created by operation of an engine includes a plurality of pendulums moveable with respect to a rotatable shaft. The pendulums are connected to the rotatable shaft by a plurality of pins that extend through apertures in the pendulum. The pendulums each move along a path defined by various drive line or powertrain parameters and characteristics. The path is implemented by contouring an active section of the apertures that engage the pins. 
         [0007]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0008]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
           [0009]      FIG. 1  is a schematic view of an exemplary CPVA according to the principles of the present invention; 
           [0010]      FIG. 2  is an enlarged view of a pendulum mass used in the CPVA shown in  FIG. 1 ; 
           [0011]      FIG. 3  is a coordinate system illustrating the path of the pendulum mass according to the principles of the present invention; and 
           [0012]      FIG. 4  is a schematic view of another exemplary CPVA according to the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. With reference to  FIG. 1 , a centrifugal pendulum vibration absorber (CPVA) is generally indicated by reference number  10 . The CPVA  10  includes a rotating engine shaft or plate  12  and a plurality of pendulum masses  14  that are moveably connected with the first plate  12 . The plate  12  is driven by an engine (not shown), or other torque producing machine to provide a driving torque to the plate  12 . Accordingly, the plate  12  is rotatable about an axis “A” concentric with the plate  12 . The plate  12  is any plate that mounts to an output shaft of an engine such as, for example, a flywheel or flexplate. The plate  12  is operable to transmit torque from the engine to another component within the motor vehicle, such as an axle shaft or transmission component. For example, the plate  12  may be connected to another rotatable plate or member (not shown) that is preferably part of a torque transmitting device such as, for example, a torque converter of an automatic transmission or a clutch of a manual transmission. However, it should be appreciated that the plate  12  may be connected to various other components within a powertrain drive line without departing from the scope of the present invention. 
         [0014]    The pendulum masses  14  are each moveably connected with the first plate  12 , where each of the pendulum masses  14  includes two apertures  16 A and  16 B located within the pendulum masses  14 . Corresponding pins  18  connected to the plate  12  are provided for each aperture  16 , where each aperture  16  receives one of the pins  18  therethrough. Each of the pins  18  have circular cross-sections with a radius of “r”. The apertures  16 A and  16 B are defined by an internal surface  20  of the pendulum mass  14  that includes a first surface or active section  22  and a second surface or passive section  24 . The active section  22  defines the path of the pendulum mass  16 , as will be described in greater detail below. The passive section  24  preferably has a straight contour, though other contours may be employed without departing from the scope of the present invention. Each of the plurality of pendulum masses  14  are circumferentially arranged in a substantially symmetrical pattern around the rotational axis “A” of the plate  12 . In the present embodiment, four pendulum masses  14  are included with the CPVA  10 , however those skilled in the art will appreciate that any number of pendulum masses  14  may be employed. 
         [0015]    When the plate  12  is at rest, the pendulum masses  14  each remain generally stationary and do not move substantially. However, each pendulum mass  14  oscillates or travels about the corresponding pins  18  when the plate  12  rotates about the axis “A”. For example, as the pendulum mass  14  travels about the corresponding pins  18 , a portion of an outer surface  26  of the pins  18  slides along the active section  22  of each aperture  16 A and  16 B. Accordingly, each pendulum mass  14  travels about a specific path that is determined by the contour of the active section  22  which controls the movement of the pendulum mass  14  about the corresponding pins  18 . The movement of the pendulum masses  14  along the paths counteract at least some of the torque fluctuations that are created as the engine operates, which thereby reduces torsional vibration. 
         [0016]    Turning to  FIG. 2 , the pendulum masses  14  will be described in greater detail with reference to one of the pendulum masses  14 , it being understood that each of the pendulum masses  14  are identical in the present embodiment. The pendulum mass  14  includes a center of mass “m”. Each of the apertures  16 A and  16 B are located equidistant and symmetrical from the center of mass “m”. In addition, each of the apertures  16 A and  16 B are identically shaped. 
         [0017]    Turning to  FIG. 3 , a coordinate system used to define the path of the center of mass “m” of the pendulum  14  during rotation of the plate  12  is illustrated. “A” is the rotational axis that is the center of the rotary motion of the plate  12 . A Cartesian coordinate (x, y) rotates with the plate  12 . The origin of the Cartesian coordinate is “o”. The distanced from the rotational axis “A” to “o” is defined by a constant “R”. The x axis of the Cartesian coordinate lays on the extended straight line connecting the points “A” and “o”. “m” is the center of mass of the pendulum mass  14 , as described above. “l” is the length of the straight line from the point “o” to center of mass “m”. φ is the angle between the x axis and the line “l”. Accordingly, φ is the angular displacement of the pendulum mass  14 . θ is the angular displacement of the plate  12 . The center of mass “m” of the pendulum mass  14  travels along a path “P”. 
         [0018]    The path “P” may be defined using the Cartesian coordinate system with the following equations (1) and (2): 
         [0000]        x=b (1 +k   1 φ 2   +k   2 φ 4 )cos(φ)  (1)
 
         [0000]        y=b (1 +k   1 φ 2   +k   2 φ 4 )sin(φ)  (2)
 
         [0019]    Alternatively, the path “P” may be defined using the distance “l” from the origin “o” of the Cartesian coordinate system using the following equation (3): 
         [0000]        l=b (1 +k   1 φ 2   +k   2 φ 4 )  (3)
 
         [0020]    In equations (1), (2), and (3), the variable “b” is employed to tune the CPVA  10 . The variable “b” is calculated using the following equation (4): 
         [0000]    
       
         
           
             
               
                 
                   
                     R 
                     b 
                   
                   = 
                   
                     λ 
                      
                     
                         
                     
                      
                     
                       n 
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
         [0021]    In equation (4), “n” is the engine torque oscillation order which is an integer that is defined as the number of engine torque oscillations per every engine revolution. The variable “R” is, as noted above, the distance between the rotational axis “A” of the plate  12  and the origin of the Cartesian coordinate system “o”. The variable λ has a value that preferably is between 1 to approximately 1.3. The actual value of λ is dependent on dynamic characteristics the drive line of the motor vehicle. λ is preferably determined through dynamic analysis using simulation models on the specific drive line within which the CPVA  10  is installed. 
         [0022]    In equations (1), (2), and (3), the variables “k 1 ” and “k 2 ” are based on the engine torque oscillation order “n” according to Table 1 below: 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Engine Order (n) 
                 Value of k 1   
                 Value of k 2   
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 2 
                 0.025 
                 −0.1 
               
               
                 3 
                 0.026 
                 −0.14 
               
               
                 4 
                 0.028 
                 −0.16 
               
               
                   
               
             
          
         
       
     
         [0023]    Returning to  FIG. 2 , in order to implement the path “P” of the pendulum mass  14 , the contour of the active section  22  for each of the apertures  16 A and  16 B is defined using either Cartesian coordinates x and y or by an angle φ and distance l from an origin point “o” of the Cartesian coordinate system. The active section  22  may be defined using a Cartesian coordinate system having an origin “o” a distance “R” from the center of rotation of the plate  12  and y axis of the Cartesian coordinate lays on the extended straight line connecting the center-point  28  and “o” the with the following equations (5) and (6) 
         [0000]    
       
         
           
             
               
                 
                   x 
                   = 
                   
                     
                       
                         b 
                          
                         
                           ( 
                           
                             1 
                             + 
                             
                               
                                 k 
                                 1 
                               
                                
                               
                                 ϕ 
                                 2 
                               
                             
                             + 
                             
                               
                                 k 
                                 2 
                               
                                
                               
                                 ϕ 
                                 4 
                               
                             
                           
                           ) 
                         
                       
                        
                       
                         cos 
                          
                         
                           ( 
                           ϕ 
                           ) 
                         
                       
                     
                     + 
                     
                       r 
                        
                       
                         
                           { 
                           
                             
                               
                                 b 
                                  
                                 
                                   ( 
                                   
                                     
                                       2 
                                        
                                       
                                         k 
                                         1 
                                       
                                        
                                       ϕ 
                                     
                                     + 
                                     
                                       4 
                                        
                                       
                                         k 
                                         2 
                                       
                                        
                                       
                                         ϕ 
                                         3 
                                       
                                     
                                   
                                   ) 
                                 
                               
                                
                               
                                 sin 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                             + 
                             
                               
                                 b 
                                  
                                 
                                   ( 
                                   
                                     1 
                                     + 
                                     
                                       
                                         k 
                                         1 
                                       
                                        
                                       
                                         ϕ 
                                         2 
                                       
                                     
                                     + 
                                     
                                       
                                         k 
                                         2 
                                       
                                        
                                       
                                         ϕ 
                                         4 
                                       
                                     
                                   
                                   ) 
                                 
                               
                                
                               
                                 cos 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                           
                           } 
                         
                         
                           
                             { 
                             
                               
                                 
                                   ( 
                                   
                                     b 
                                      
                                     
                                       ( 
                                       
                                         
                                           2 
                                            
                                           
                                             k 
                                             1 
                                           
                                            
                                           ϕ 
                                         
                                         + 
                                         
                                           4 
                                            
                                           
                                             k 
                                             2 
                                           
                                            
                                           
                                             ϕ 
                                             3 
                                           
                                         
                                       
                                       ) 
                                     
                                   
                                   ) 
                                 
                                 2 
                               
                               + 
                               
                                 
                                   
                                     
                                       b 
                                       2 
                                     
                                      
                                     
                                       ( 
                                       
                                         1 
                                         + 
                                         
                                           
                                             k 
                                             1 
                                           
                                            
                                           
                                             ϕ 
                                             2 
                                           
                                         
                                         + 
                                         
                                           
                                             k 
                                             2 
                                           
                                            
                                           
                                             ϕ 
                                             4 
                                           
                                         
                                       
                                       ) 
                                     
                                   
                                   2 
                                 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                             } 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
             
               
                 
                   y 
                   = 
                   
                     
                       
                         b 
                          
                         
                           ( 
                           
                             1 
                             + 
                             
                               
                                 k 
                                 1 
                               
                                
                               
                                 ϕ 
                                 2 
                               
                             
                             + 
                             
                               
                                 k 
                                 2 
                               
                                
                               
                                 ϕ 
                                 4 
                               
                             
                           
                           ) 
                         
                       
                        
                       
                         sin 
                          
                         
                           ( 
                           ϕ 
                           ) 
                         
                       
                     
                     + 
                     
                       r 
                        
                       
                         
                           - 
                           
                             { 
                             
                               
                                 
                                   b 
                                    
                                   
                                     ( 
                                     
                                       
                                         2 
                                          
                                         
                                           k 
                                           1 
                                         
                                          
                                         ϕ 
                                       
                                       + 
                                       
                                         4 
                                          
                                         
                                           k 
                                           2 
                                         
                                          
                                         
                                           ϕ 
                                           3 
                                         
                                       
                                     
                                     ) 
                                   
                                 
                                  
                                 
                                   cos 
                                    
                                   
                                     ( 
                                     ϕ 
                                     ) 
                                   
                                 
                               
                               - 
                               
                                 
                                   b 
                                    
                                   
                                     ( 
                                     
                                       1 
                                       + 
                                       
                                         
                                           k 
                                           1 
                                         
                                          
                                         
                                           ϕ 
                                           2 
                                         
                                       
                                       + 
                                       
                                         
                                           k 
                                           2 
                                         
                                          
                                         
                                           ϕ 
                                           4 
                                         
                                       
                                     
                                     ) 
                                   
                                 
                                  
                                 
                                   sin 
                                    
                                   
                                     ( 
                                     ϕ 
                                     ) 
                                   
                                 
                               
                             
                             } 
                           
                         
                         
                           
                             { 
                             
                               
                                 
                                   ( 
                                   
                                     b 
                                      
                                     
                                       ( 
                                       
                                         
                                           2 
                                            
                                           
                                             k 
                                             1 
                                           
                                            
                                           ϕ 
                                         
                                         + 
                                         
                                           4 
                                            
                                           
                                             k 
                                             2 
                                           
                                            
                                           
                                             ϕ 
                                             3 
                                           
                                         
                                       
                                       ) 
                                     
                                   
                                   ) 
                                 
                                 2 
                               
                               + 
                               
                                 
                                   
                                     
                                       b 
                                       2 
                                     
                                      
                                     
                                       ( 
                                       
                                         1 
                                         + 
                                         
                                           
                                             k 
                                             1 
                                           
                                            
                                           
                                             ϕ 
                                             2 
                                           
                                         
                                         + 
                                         
                                           
                                             k 
                                             2 
                                           
                                            
                                           
                                             ϕ 
                                             4 
                                           
                                         
                                       
                                       ) 
                                     
                                   
                                   2 
                                 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                             } 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
         [0024]    In equations (5) and (6), the variable “r” is the radius of the pins  18  as noted above. Alternatively, the active section  22  may be defined using the distance “l” from the origin “o” of the Cartesian coordinate system using the following equation (7): 
         [0000]        l=r+b (1 +k   1 φ 2   +k   2 φ 4 )  (7)
 
         [0025]    The pins  18  are located on the plate  12  such that when the pins  18  are at a center point  28  along the contour of the active section  22 , the distance from the center of mass “m” of each of the pendulum masses  14  to the rotational axis “A” or center of the plate  12  is equal to R+b. 
         [0026]    Turning to  FIG. 4 , an alternate CPVA that implements the path “P” of the center of mass “m” of the pendulum masses  14  is generally indicated by  10 ′. The CPVA  10 ′ is similar to the CPVA  10  and therefore like components are indicated by like reference numbers. However, plate  12  includes two apertures  30 A and  30 B and the pins  18  are replaces with rollers  32 . The rollers  32  are not fixedly connected to the plate  12 . The apertures  30 A and  30 B are in partial axial alignment with apertures  16 A and  16 B and have identical contours of their active sections  22 , though apertures  30 A and  30 B are mirror images of apertures  16 A and  16 B. The rollers  32  have a circular cross-section and a radius “r”. The rollers  32  ride on the active sections  22  of both the apertures  16 A and  30 A and  16 B and  30 B. The active sections  22  are formed in the same manner as those used in CPVA  10  described above and are defined by the following equations (8) and (9): 
         [0000]    
       
         
           
             
               
                 
                   x 
                   = 
                   
                     
                       
                         b 
                         2 
                       
                        
                       
                         ( 
                         
                           1 
                           + 
                           
                             
                               k 
                               1 
                             
                              
                             
                               ϕ 
                               2 
                             
                           
                           + 
                           
                             
                               k 
                               2 
                             
                              
                             
                               ϕ 
                               4 
                             
                           
                         
                         ) 
                       
                        
                       
                         cos 
                          
                         
                           ( 
                           ϕ 
                           ) 
                         
                       
                     
                     + 
                     
                       r 
                        
                       
                         
                           { 
                           
                             
                               
                                 b 
                                 2 
                               
                                
                               
                                 ( 
                                 
                                   
                                     2 
                                      
                                     
                                       k 
                                       1 
                                     
                                      
                                     ϕ 
                                   
                                   + 
                                   
                                     4 
                                      
                                     
                                       k 
                                       2 
                                     
                                      
                                     
                                       ϕ 
                                       3 
                                     
                                   
                                 
                                 ) 
                               
                                
                               
                                 sin 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                             + 
                             
                               
                                 b 
                                 2 
                               
                                
                               
                                 ( 
                                 
                                   1 
                                   + 
                                   
                                     
                                       k 
                                       1 
                                     
                                      
                                     
                                       ϕ 
                                       2 
                                     
                                   
                                   + 
                                   
                                     
                                       k 
                                       2 
                                     
                                      
                                     
                                       ϕ 
                                       4 
                                     
                                   
                                 
                                 ) 
                               
                                
                               
                                 cos 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                           
                           } 
                         
                         
                           
                             { 
                             
                               
                                 
                                   ( 
                                   
                                     
                                       b 
                                       2 
                                     
                                      
                                     
                                       ( 
                                       
                                         
                                           2 
                                            
                                           
                                             k 
                                             1 
                                           
                                            
                                           ϕ 
                                         
                                         + 
                                         
                                           4 
                                            
                                           
                                             k 
                                             2 
                                           
                                            
                                           
                                             ϕ 
                                             3 
                                           
                                         
                                       
                                       ) 
                                     
                                   
                                   ) 
                                 
                                 2 
                               
                               + 
                               
                                 
                                   
                                     ( 
                                     
                                       b 
                                       2 
                                     
                                     ) 
                                   
                                   2 
                                 
                                  
                                 
                                   
                                     ( 
                                     
                                       1 
                                       + 
                                       
                                         
                                           k 
                                           1 
                                         
                                          
                                         
                                           ϕ 
                                           2 
                                         
                                       
                                       + 
                                       
                                         
                                           k 
                                           2 
                                         
                                          
                                         
                                           ϕ 
                                           4 
                                         
                                       
                                     
                                     ) 
                                   
                                   2 
                                 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                             } 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   8 
                   ) 
                 
               
             
             
               
                 
                   y 
                   = 
                   
                     
                       
                         b 
                         2 
                       
                        
                       
                         ( 
                         
                           1 
                           + 
                           
                             
                               k 
                               1 
                             
                              
                             
                               ϕ 
                               2 
                             
                           
                           + 
                           
                             
                               k 
                               2 
                             
                              
                             
                               ϕ 
                               4 
                             
                           
                         
                         ) 
                       
                        
                       
                         sin 
                          
                         
                           ( 
                           ϕ 
                           ) 
                         
                       
                     
                     + 
                     
                       r 
                        
                       
                         
                           - 
                           
                             { 
                             
                               
                                 
                                   b 
                                   2 
                                 
                                  
                                 
                                   ( 
                                   
                                     
                                       2 
                                        
                                       
                                         k 
                                         1 
                                       
                                        
                                       ϕ 
                                     
                                     + 
                                     
                                       4 
                                        
                                       
                                         k 
                                         2 
                                       
                                        
                                       
                                         ϕ 
                                         3 
                                       
                                     
                                   
                                   ) 
                                 
                                  
                                 
                                   cos 
                                    
                                   
                                     ( 
                                     ϕ 
                                     ) 
                                   
                                 
                               
                               - 
                               
                                 
                                   b 
                                   2 
                                 
                                  
                                 
                                   ( 
                                   
                                     1 
                                     + 
                                     
                                       
                                         k 
                                         1 
                                       
                                        
                                       
                                         ϕ 
                                         2 
                                       
                                     
                                     + 
                                     
                                       
                                         k 
                                         2 
                                       
                                        
                                       
                                         ϕ 
                                         4 
                                       
                                     
                                   
                                   ) 
                                 
                                  
                                 
                                   sin 
                                    
                                   
                                     ( 
                                     ϕ 
                                     ) 
                                   
                                 
                               
                             
                             } 
                           
                         
                         
                           
                             { 
                             
                               
                                 
                                   ( 
                                   
                                     
                                       b 
                                       2 
                                     
                                      
                                     
                                       ( 
                                       
                                         
                                           2 
                                            
                                           
                                             k 
                                             1 
                                           
                                            
                                           ϕ 
                                         
                                         + 
                                         
                                           4 
                                            
                                           
                                             k 
                                             2 
                                           
                                            
                                           
                                             ϕ 
                                             3 
                                           
                                         
                                       
                                       ) 
                                     
                                   
                                   ) 
                                 
                                 2 
                               
                               + 
                               
                                 
                                   
                                     ( 
                                     
                                       b 
                                       2 
                                     
                                     ) 
                                   
                                   2 
                                 
                                  
                                 
                                   
                                     ( 
                                     
                                       1 
                                       + 
                                       
                                         
                                           k 
                                           1 
                                         
                                          
                                         
                                           ϕ 
                                           2 
                                         
                                       
                                       + 
                                       
                                         
                                           k 
                                           2 
                                         
                                          
                                         
                                           ϕ 
                                           4 
                                         
                                       
                                     
                                     ) 
                                   
                                   2 
                                 
                                  
                                 
                                   ( 
                                   ϕ 
                                   ) 
                                 
                               
                             
                             } 
                           
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
     
         [0027]    The active sections  22  of the apertures  30 A and  30 B are located on the plate  12  such that when the rollers  32  are in contact with the centers  28  of both apertures  16 A and  30 A and  16 B and  30 B, the distance from the center of mass “m” of the pendulum mass  14  to the rotational axis “A” or center of the plate  12  is equal to R+b. 
         [0028]    The path “P” described above provides an improved vibration reduction over circular and cycloidal paths. In addition, the path “P” allows for quick and stable transient response during rapid engine speed changes. 
         [0029]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.