Abstract:
The dual mass flywheel reduces torsional vibrations by being mounted between the engine and the transmission, The dual mass flywheel includes a primary mass configured to couple to a crankshaft, and a first drive plate coupled to said primary mass by disposing a main elastic member therebetween. A pair of second drive plates are coupled to said first drive plate by disposing an idle elastic member therebetween. A secondary mass is fixedly coupled to said pair of second drive plates.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to an apparatus for damping vibrations, and more particularly, to an apparatus for damping torsional vibrations that occur in a torque transmission process. The apparatus is installed between an end of an engine&#39;s crank shaft and a transmission.  
         BACKGROUND OF THE INVENTION  
         [0002]    In general, a dual mass flywheel includes a primary mass and a secondary mass which are relatively rotatable within a limited range and an elastic member for damping the torsional vibrations by being installed between the primary and secondary masses while transmitting a rotational force.  
           [0003]    Such dual mass flywheels play a role of damping the torsional vibrations which occur when transmitting torque. The vibrations are caused by a sudden increase or decrease in the number of revolutions of the engine—from the engine to the transmission.  
           [0004]    The primary mass engages an output element (for example, the crank shaft) of the engine and the secondary mass engages an input element of the transmission. The secondary mass and an input side of the transmission are engaged and disengaged through a clutch. In general, the primary mass and the secondary mass are connected by means of a spring.  
           [0005]    However, it is difficult to obtain optimal damping characteristics using current dual mass flywheels, where the optimal characteristics are based on the torque characteristics for each number of revolutions.  
         SUMMARY OF THE INVENTION  
         [0006]    An exemplary dual mass flywheel useful with the present invention includes a primary mass engagable with a crankshaft. A first drive plate is coupled to said primary mass by disposing a main elastic member therebetween. A pair of second drive plates are coupled to said first drive plate by disposing an idle elastic member therebetween. A secondary mass is fixedly coupled to said pair of second drive plates. The first drive plate has a first main elastic member recess formed in circumferential direction thereof. The dual mass flywheel further comprises a pair of covers enclosing the first drive plate on both sides of said first drive plate and fixedly coupled to said primary mass. The pair of covers each have a second main elastic member recess formed in circumferential direction thereof in a position corresponding to that of said first main elastic member recess of said first drive plate. The main elastic members is inserted into said main elastic member recess of said first drive plate and said second main elastic member recess of each of said covers at the same time so as to be compressed between said covers and said first drive plate.  
           [0007]    In addition, the first drive plate has a first stopper recess of arcuate-shape formed in a circumferential direction thereof and having a predetermined width. The dual mass flywheel further comprises a first stopper fixedly coupled between said pair of covers so as to be movable along said first stopper recess.  
           [0008]    Further, the first drive plate has a first idle elastic member recess formed in a circumferential direction thereof. The pair of second drive plates each have a second idle elastic member recess formed in a position corresponding to that of said first idle elastic member recess. The idle elastic member is inserted into said first and second idle elastic member recesses at the same time so as to be compressed between said first drive plate and said second drive plates.  
           [0009]    The idle elastic member preferably includes: a first idle spring; a pair of spring guides; and a second idle spring arranged between said pair of spring guides so as to elastically support said pair of spring guides.  
           [0010]    The first drive plate has a second stopper recess of arcuate-shape formed in a circumferential direction thereof and having a predetermined width. The dual mass flywheel further includes a second stopper fixedly coupled between said pair of second drive plates so as to be movable along said second stopper recess.  
           [0011]    A dual mass flywheel according to another embodiment of the present invention includes a primary mass configured to couple with a crankshaft. A secondary mass is coupled so as to be relatively rotatable with respect to said primary mass within a predetermined range. A first drive plate is coupled so as to be relatively rotatable with respect to said primary mass within a predetermined range. A first damping device disposed between said primary mass and said first drive plate. A second drive plate fixedly coupled to said secondary mass and coupled so as to be relatively rotatable with respect to said first drive plate within a predetermined range. A second damping device is disposed between said second drive plate and said first drive plate.  
           [0012]    Also, said first drive plate has a first spring recess formed in circumferential direction thereof. The first damping device also includes a pair of covers which are fixedly coupled to said primary mass and which each have a second spring recess formed in a position corresponding to that of said first spring recess, and a main spring which is inserted into said first and second recesses at the same time.  
           [0013]    In addition, first drive plate further includes a first stopper recess formed in a circumferential direction thereof. The first damping device further includes a first stopper fixedly coupled between said pair of covers and movably arranged in said first stopper recess. The first drive plate includes a third spring recess formed in a circumferential direction thereof. The second drive plate includes a fourth spring recess formed in a position corresponding to that of said third spring recess. The second damping device includes a first idle spring inserted into said third and fourth spring recesses at the same time, and a second idle spring inserted into said first idle spring and supported at their both sides by means of guides.  
           [0014]    The first drive plate further includes a second stopper recess formed in circumferential direction thereof. The dual mass flywheel further includes a second stopper fixedly coupled to said second drive plate and installed to be movable along said second stopper recess. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention:  
         [0016]    [0016]FIG. 1 is a perspective view showing a front side of a dual mass flywheel, according to a preferred embodiment of the present invention;  
         [0017]    [0017]FIG. 2 is a perspective view showing a rear side of a dual mass flywheel according to a preferred embodiment of the present invention;  
         [0018]    [0018]FIG. 3 is a sectional view of the dual mass flywheel according to the preferred embodiment of the present invention;  
         [0019]    [0019]FIG. 4 shows internal structure of the dual mass flywheel according to the preferred embodiment of the present invention; and  
         [0020]    FIGS.  5  to  7  show a first drive plate, a first drive plate cover and a second drive plate of the dual mass flywheel according to the preferred embodiment of the present invention, respectively. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    A preferred embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.  
         [0022]    As shown in FIGS. 1 and 2, a dual mass flywheel  100  according to a preferred embodiment of the present invention includes a primary mass  101  a secondary mass  103 , and a ring gear  105  arranged on an outer circumference of the primary mass  101 .  
         [0023]    [0023]FIG. 3 is a sectional view showing the internal structure of the dual mass flywheel  100  according to the preferred embodiment of the present invention. The primary mass  101  has a circular through hole at its center part and a hub  107  is inserted into the through hole. The primary mass  101  and the hub  107  are fixedly engaged with an engine crankshaft  111  by means of rivets  109 . Therefore, the primary mass  101  and the engine crankshaft  111  rotate around a rotational axis R-R as one piece.  
         [0024]    The primary mass  101  has a radially extending body part  113  and a flange part  115  extending in a direction parallel to the rotational axis R-R from a periphery of the body part  113 .  
         [0025]    As shown in FIG. 4, the primary mass  101  is connected a first drive plate  117  by disposing therebetween main springs  119  having a spring constant of a predetermined magnitude. The primary mass  101  is fixedly engaged to a pair of covers  121  by means of rivets  123 . As shown in FIGS. 4 and 6, the cover  121  is provided with a plurality of rivet holes  125  formed in a circumferential direction thereof. First stoppers  127  are arranged between the rivet holes  125  each facing the other of the pair of covers  121 . The first stoppers  127  include rivet holes  135 . The rivets  123  are inserted through the rivet holes  125  and  135  so that the first stoppers  127  are fixedly engaged between the pair of covers  121 . Although four stoppers  127  are shown in a preferred embodiment of the present invention, it should be appreciated that any suitable number of stoppers may be used.  
         [0026]    In addition, as shown in FIG. 6, four recesses  129  are formed in circumferential direction in the cover  121 , in which the main springs  119  are arranged. However, it should be apparent that any suitable number of main springs  119  and recesses  129  may be used.  
         [0027]    A first drive plate  117  is arranged between the pair of covers  121 . As shown in FIGS. 4 and 5, the first drive plate  117  is a circular plate. Spring recesses  131  of predetermined size and stopper recesses  133  of predetermined size are alternatingly formed in a circumferential direction of the first drive plate  117 . The spring recesses  131  of the first drive plate  117  and the recesses  129  of the cover  121  are formed in positions corresponding to each other and the main springs  119  are arranged in the two recesses  131  and  129 . Also, first stoppers  127  which are fixedly engaged between the covers  121  are movably arranged in the stopper recesses  133  formed in the first drive plate  117 .  
         [0028]    Since the pair of covers  121  are fixedly coupled to the primary mass  101 , where the primary mass  101  rotates, the covers  121  rotate together with the primary mass  101 . When the covers  121  rotate, the main springs  119  are compressed and, thereby, transmit a rotational force to the first drive plate  117 . At this time, the first stoppers  127  fixedly engaged between the pair of covers  121  are moved along the stopper recesses  133  formed in the first drive plate  117 .  
         [0029]    If the primary mass  101  and the first drive plate  117  rotate relative to each other and the first stoppers  127  reach an end of the stopper recesses  133 , then the primary mass  101  and the first drive plate  117  rotate as one piece. Limiting the stopper recesses  133  to a certain size as described above prevents the main springs  119  from being excessively compressed, thereby avoiding damaging the elastic force of the main springs  119 .  
         [0030]    A pair of second drive plates  137  are coupled to inside the first drive plate  117  by disposing therebetween first idle springs  139  and second idle springs  141 .  
         [0031]    As shown in FIG. 7, the second drive plates  137  have a plurality of rivet holes  143  formed around a circumferential direction thereof. The second drive plates  137  are fixedly coupled to a secondary mass  103  by means of rivets through the rivet holes  143 . The secondary mass  103  is coupled rotatably the hub  107  via a bearing with the primary mass  101 .  
         [0032]    A plurality of idle spring recesses  147  are formed inside the first drive plate  117  in circumferential direction thereof. A plurality of spring recesses  149  are formed in the second drive plate  137  in positions corresponding to the spring recesses  147  of the first drive plate  117 . The first idle springs  139  and the second idle springs  141  are arranged in the two spring recesses  147  and  149 .  
         [0033]    As shown in FIG. 4, the second idle springs  141  are arranged inside the first idle springs  139  and the spring constant of the second idle springs  141  has a value smaller than that of the spring constant of the first idle springs  139 . Furthermore, the spring constant of the first idle springs  139  has a value smaller than that of the spring constant of the main springs  119 .  
         [0034]    Both sides of the second idle springs  141  are supported by means of a pair of idle spring guides  151 . That is, the idle spring guides  151  are elastically supported by means of the second idle springs  141  and abut both ends of the two spring recesses  147  and  149 .  
         [0035]    The length of the first idle springs  139  in their equilibrium state is smaller than width of the two recesses  147  and  149 , and the idle spring guides  151  are inserted into both ends of the first idle springs  139 . Therefore, if a rotational angle occurs between the first drive plate  117  and the second drive plate  137 , the second idle springs  141  are first compressed to a certain degree or more, and thereafter the first idle springs  139  are compressed.  
         [0036]    Covers  153  are provided towards the outer side of the spring recesses  149  of the second drive plate  137 , extending in a circumferential direction thereof. Open chambers are formed between the covers  153  respectively formed in the recesses  149  of the pair of opposing second drive plates  137 . The first idle springs  139  and the second idle springs  141  are arranged in the chambers to prevent them from escaping the recesses  149 .  
         [0037]    Rivet holes  155  are formed between the spring recesses  149  in circumferential direction of the second drive plates  137 . Second stoppers  157  are coupled between the rivet holes  155  facing each of the pair of second drive plates  137 . In addition, in the first drive plates  117 , stopper recesses  159  are formed in circumferential direction of the first drive plate  117  which have a certain width and are provided in positions corresponding to the second stoppers  157 .  
         [0038]    When relative rotation occurs between the first drive plate  117  and the second drive plates  137 , the second stoppers  157  rotate along the stopper recesses  159 . When the relative rotational displacement is increased so that the second stoppers  157  abut an end of the stopper recesses  159 , the relative displacement is not further increased and the first drive plate  117  and the second drive plates  137  rotate as one piece.  
         [0039]    The dual mass flywheel installed between the crankshaft of the engine and the input side of the transmission transmits a rotational force from the engine to the transmission or vice versa. The dual mass flywheel effectively dampens the torsional vibration generated when transmitting the rotational force.  
         [0040]    Where an engine is driven for the first time, or where there is a sudden increase in the rotational speed of the engine, a difference in the rotational speeds between the primary mass  101 , coupled to the crankshaft, and the second mass  103 , connected to the input side of the transmission, occurs. Accordingly, a difference in rotational speed occurs between the pair of covers  121  fixedly coupled to the primary mass  101  and the first drive plate  117 . Consequently, a rotational angle is generated between the covers  121  and the first drive plate  117 . The plurality of main springs  119  disposed between the covers  121  and the first drive plate  117  are compressed and the rotational force is transmitted to the first drive plate  117 .  
         [0041]    When the first drive plate  117  rotates, the second idle springs  141  disposed between the first drive plate  117  and the second drive plates  137  are first compressed to transmit the rotational force to the second drive plates  137 . When the second idle springs  141  are compressed to a certain degree, the first idle springs  139  start to be compressed to transmit the rotational force to the second drive plates  137  and eventually to the secondary mass  103  fixedly engaged with the second drive plates  137 . At this time, the second idle springs  141  having smaller spring constant are first compressed and then the first idle springs  139  are compressed, thereby obtaining a stepwise damping effect.  
         [0042]    As described above, the dual mass flywheel according to the preferred embodiment of the present invention can efficiently perform damping so as to efficiently prevent a rattle noise or a booming phenomenon of the transmission. In addition, such a dual mass-flywheel can obtain a stepwise damping effect by means of the main springs and the first and second idle springs, even in the case of sudden torque changes.  
         [0043]    While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.