Patent Publication Number: US-9416845-B2

Title: Damper with torque limiter

Description:
TECHNICAL FIELD 
     The present invention relates to improvement of a damper with a torque limiter in which a mass ring is linked to a drive plate linked to an input shaft, a spring holder is linked to the mass ring via a torque limiter, a driven plate linked to an output shaft is disposed within the spring holder, and a damper spring is disposed so as to straddle the spring holder and the driven plate, the damper spring being compressed by relative rotation of the spring holder and the driven plate. 
     BACKGROUND ART 
     Such a damper with a torque limiter is arranged so that when a variation in torque occurs between the input shaft and the output shaft, the torque variation is absorbed by virtue of compressive deformation of the damper spring, and when excessive torque acts between the input shaft and the output shaft, transmission of torque is blocked by slipping of the torque limiter; such a damper with a torque limiter is already known, as disclosed in Patent Document 1 below. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: Japanese Patent Application Laid-open No. 2010-236601 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     In a conventional damper with a torque limiter, a spring holder is formed from a pair of mutually opposing holder plates; when these two holder plates are joined, a friction plate is added thereto, and the three are joined using a common rivet. Therefore, in such an arrangement, transmission of torque between the friction plate and the spring holder is mediated by the rivet, and since it is necessary for the rivet to have a strength that can withstand the transmission of torque, the diameter is inevitably increased, thus resulting in an increase in weight and cost. 
     The present invention has been accomplished in light of such circumstances, and it is an object thereof to provide a damper with a torque limiter in which a rivet providing a link between a pair of holder plates forming a spring holder does not carry the burden of torque transmission, thus enabling the diameter of the rivet to be made small and thereby enabling the weight and the cost to be reduced. 
     Means for Solving the Problems 
     In order to attain the above object, according to a first aspect of the present invention, there is provided a damper with a torque limiter in which a mass ring is linked to a drive plate linked to an input shaft, a spring holder is linked to the mass ring via a torque limiter, a driven plate linked to an output shaft is disposed within the spring holder, and a damper spring is disposed so as to straddle the spring holder and the driven plate, the damper spring being compressed by relative rotation of the spring holder and the driven plate, characterized in that the torque limiter is formed from an annular limiter housing that is formed on an inner peripheral side of the mass ring, a friction plate that has one side face frictionally engaging with one side face of the limiter housing, a pressure-applying plate that engages with the other side face of the friction plate and that is linked to the mass ring, and a limiter spring that is capable of urging the pressure-applying plate toward the friction plate side and generating a predetermined frictional torque between the friction plate and the mass ring and pressure-applying plate, the spring holder is formed from a pair of first and second holder plates that oppose each other so as to define a damper housing for housing the damper spring and the driven plate and that are joined to each other by a rivet, and the friction plate is formed integrally with the second holder plate. It should be noted here that the input shaft corresponds to a crankshaft  1  of an embodiment of the present invention, which will be described hereinafter. 
     Further, according to a second aspect of the present invention, in addition to the first aspect, a plurality of centering projections are formed on an outer peripheral face of the friction plate, the centering projections sliding on an inner peripheral face of the limiter housing so as to carry out centering of the friction plate with respect to the mass ring. 
     Furthermore, according to a third aspect of the present invention, in addition to the first or second aspect, the friction plate and the second holder plate are formed from a steel plate having a plate thickness that is smaller than that of the first holder plate, and a plurality of annular bent parts are formed on the second holder plate. 
     Effects of the Invention 
     In accordance with the first aspect of the present invention, since the torque limiter is formed from the annular limiter housing that is formed on the inner peripheral side of the mass ring, the friction plate that has one side face frictionally engaging with one side face of the limiter housing, the pressure-applying plate that frictionally engages with the other side face of the friction plate and that is linked to the mass ring, and the limiter spring that is capable of urging the pressure-applying plate toward the friction plate side and generating a predetermined frictional torque between the friction plate and the mass ring and pressure-applying plate, the spring holder is formed from the pair of first and second holder plates that oppose each other so as to define the damper housing housing the damper spring and the driven plate and that are joined to each other by means of the rivet, and the friction plate is formed integrally with the second holder plate, a torque that acts from the mass ring on the friction plate of the torque limiter is transmitted directly to the second holder plate and does not act on the rivet. Therefore, it is possible to join the first and second holder plates by means of the rivet, which has a relatively small diameter, thereby contributing to lightening of the weight and a reduction in cost. 
     In accordance with the second aspect of the present invention, since the plurality of centering projections, which slide on the inner peripheral face of the limiter housing so as to carry out centering of the friction plate with respect to the mass ring, are formed on the outer peripheral face of the friction plate, the friction plate, the spring holder, and the driven plate are individually centered with respect to the mass ring, and when the drive plate joined to the input shaft is joined to the mass ring during assembly, the input shaft and the hub of the driven plate are coaxially aligned, thus making it possible to easily and appropriately spline fit the output shaft, which is positioned coaxially with the input shaft, into the hub of the driven plate, and thereby improving the ease of assembly. 
     In accordance with the third aspect of the present invention, since the friction plate and the second holder plate are formed from a steel plate having a plate thickness that is smaller than that of the first holder plate, it is possible to decrease the axial dimension of the torque limiter, thus making the torque limiter compact. Moreover, although the second holder plate has a small plate thickness, it has the plurality of annular bent parts by which it is reinforced effectively, thus enabling a sufficient strength to be imparted to the spring holder in cooperation with the first holder plate, which has a large plate thickness, and this can also contribute to lightening of the weight of the spring holder. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view relating to an embodiment of the present invention (first embodiment). 
         FIG. 2  is a sectional view along line  2 - 2  in  FIG. 1  (first embodiment). 
         FIG. 3  is a sectional view along line  3 - 3  in  FIG. 2  (first embodiment). 
     
    
    
     EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS 
     
         
         D Damper with torque limiter 
           1  Input shaft (crankshaft) 
           2  Output shaft 
           3  Mass ring 
           4  Torque limiter 
           5  Spring holder 
           6  Damper spring 
           7  Drive plate 
           12  Limiter housing 
           13  Driven plate 
           15  Friction plate 
           16  Pressure-applying plate 
           17  Limiter spring 
           21  First holder plate 
           22  Second holder plate 
           23  Rivet 
           24  Damper housing 
           36  Centering projection 
       
    
     MODES FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention is explained below by reference to the attached drawings. 
     First Embodiment 
     In  FIG. 1  to  FIG. 3 , the power of a crankshaft  1  of an engine is transmitted to an output shaft  2 , which is connected to a clutch or a transmission, via a damper D with a torque limiter  4  of the present invention. 
     The damper D  4  includes a mass ring  3 , a torque limiter  4 , a spring holder  5 , a plurality of damper springs  6 , and a driven plate  13 . 
     A drive plate  7  is secured to one side face of the mass ring  3  by means of a bolt  9 , the drive plate  7  being joined to the crankshaft  1  by means of a bolt  8 . A pressure-receiving plate  10  is secured to the other side face of the mass ring  3  by means of a rivet  11 , an annular limiter housing  12  is defined between the pressure-receiving plate  10  and the mass ring  3 , the limiter housing  12  opening on the inner peripheral side of the mass ring  3 , and the torque limiter  4  is disposed in the limiter housing  12 . 
     The torque limiter  4  is formed from a friction plate  15  that is rotatably and slidably fitted into the limiter housing  12  and that is adjacent to the pressure-receiving plate  10 , a pressure-applying plate  16  that is disposed so as to sandwich the friction plate  15  in cooperation with the pressure-receiving plate  10 , and a plate-shaped limiter spring  17  that is provided in a compressed state in the limiter housing  12  in order to urge the pressure-applying plate  16  toward the friction plate  15  side with a predetermined set load. The pressure-applying plate  16  includes a transmission claw  16   a  at the inner peripheral edge, and this transmission claw  16   a  engages with a cutout  18  on an inner peripheral face of the mass ring  3  to thus link the pressure-applying plate  16  to the mass ring  3  in the rotational direction. Adhered to left and right faces of the friction plate  15  are linings  19  and  19  that frictionally engage with the pressure-receiving plate  10  and the pressure-applying plate  16 . 
     The spring holder  5  is formed from a pair of left and right first and second holder plates  21  and  22 , which oppose each other, the two holder plates  21  and  22  being joined to each other by means of a rivet  23  on the outer peripheral side and forming an annular damper housing  24  on the inner peripheral side. This damper housing  24  houses a plurality of peripherally-arranged damper springs  6 , which are coil springs, pairs of retainers  26  and  26  opposing each other and supporting opposite ends of the respective damper springs  6 , and the driven plate  13 , the driven plate  13  including in a central part a hub  13   a  spline joined to the output shaft  2 . 
     The first and second holder plates  21  and  22  are provided in the sliding direction with a plurality of sets of outside guide holes  27  and  28  arranged in the axial direction as pairs, the driven plate  13  is provided with an inside guide hole  29  disposed between the outside guide holes  27  and  28  of each set, and the pair of retainers  26  and  26  are slidably fitted so as to straddle the axially-arranged outside guide holes  27  and  28  and inside guide hole  29 . 
     Housed within the damper spring  6  provided in a compressed state between each pair of retainers  26  and  26  is a secondary damper spring  31 , made of rubber, which is compressed by means of the two retainers  26  and  26  when the damper spring  6  is compressively deformed by a predetermined amount. 
     Furthermore, first and second positioning rings  32  and  33  in sliding contact with opposite side faces of the driven plate  13  are spline joined to the inner peripheral end of each of the holder plates  21  and  22 , the first positioning ring  32  being rotatably fitted around an outer peripheral face of the hub  13   a . A lining may be adhered to faces of the first and second positioning rings  32  and  33  that are in sliding contact with the driven plate  13 . 
     As shown in  FIG. 2 , the first and second holder plates  21  and  22  are both made of steel plate, but the second holder plate  22  has a smaller plate thickness than that of the first holder plate  21  and includes a first side wall  22   a  covering one side face of the driven plate  13  on the outer peripheral side, a peripheral wall  22   b  bending in the axial direction from the outer peripheral end of the first side wall  22   a  and covering an outer peripheral face of the driven plate  13 , and a second side wall  22   c  bending in the radial direction from the extremity of the peripheral wall  22   b  and being superimposed on the first holder plate  21 ; a plurality of recessed parts  35 , which are radially inwardly recessed, are formed in the peripheral wall  22   b , and the second side wall  22   c  and the first holder plate  21  are joined by means of the rivet  23  in these recessed parts  35 . 
     The second side wall  22   c  extends further in the radially outward direction, and the extending part forms the friction plate  15 . That is, the friction plate  15  and the second holder plate  22  are formed integrally from the same steel plate. 
     A plurality of centering projections  36 , which rotatably and axially slidably engage with an inner peripheral face of the limiter housing  12 , are formed integrally with an outer peripheral face of the friction plate  15  so as to be arranged in the peripheral direction, thereby allowing each of the friction plate  15 , the spring holder  5 , which is integral with the friction plate  15 , and the hub  13   a , which is fitted into the first holder plate  21  via the first positioning ring  32 , to be centered with respect to the mass ring  3 . 
     The recessed part  35  projects on the damper housing  24  side as a drive side stopper projection  37 , and a driven side stopper projection  38  is formed on the outer periphery of the driven plate  13 , the driven side stopper projection  38  opposing the drive side stopper projection  37  across a predetermined distance in the peripheral direction. 
     The operation of this embodiment is now explained. 
     The power of the crankshaft  1  of the engine is transmitted to the output shaft  2  via, in sequence, the drive plate  7 , the mass ring  3 , the torque limiter  4  (the pressure-receiving plate  10 , the pressure-applying plate  16 , the friction plate  15 ), the spring holder  5 , one retainer  26 , the damper spring  6 , the other retainer  26 , and the driven plate  13 . In this process, when a variation in torque occurs due to variation in output of the engine or variation in the load on the output shaft  2  side, the spring holder  5  and the driven plate  13  rotate relative to each other, the outside guide holes  27  and  28  of the spring holder  5  and the inside guide hole  29  of the driven plate  13  are displaced from each other, and each damper spring  6  is subjected to compressive deformation from the pair of retainers  26  and  26  supporting opposite ends of the damper spring  6 , thus absorbing the torque variation. 
     When the damper spring  6  is compressed by a predetermined value or greater due to an increase in the torque variation, this time the secondary damper spring  31  on the inside of the damper spring  6  is compressed between the retainers  26  and  26 , thus absorbing the increased torque variation. 
     When relative rotation between the spring holder  5  and the driven plate  13  reaches a predetermined angle, the drive side stopper projection  37  of the spring holder  5  abuts against the driven side stopper projection  38  of the driven plate  13 , the relative rotation is stopped, and the crankshaft  1  and the output shaft  2  rotate as a unit. 
     Subsequently, when an excessive torque is applied between the crankshaft  1  and the output shaft  2 , in the torque limiter  4  slip occurs between the friction plate  15  and the pressure-receiving plate  10  and pressure-applying plate  16 , and transmission between the crankshaft  1  and the output shaft  2  is cut off, that is, relative rotation is allowed, thereby avoiding damage to the engine or the transmission device. 
     Since the first and second holder plates  21  and  22  forming the spring holder  5  are joined by means of the rivet  23 , and the second holder plate  22  is formed integrally with the friction plate  15  of the torque limiter  4 , the torque applied from the mass ring  3  to the friction plate  15  via the pressure-receiving plate  10  and the pressure-applying plate  16  is transmitted directly to the second holder plate  22  and does not act on the rivet  23 . Therefore, it is possible to join the first and second holder plates  21  and  22  by means of the rivet  23 , which has a relatively small diameter, thus contributing to lightening of the weight and a reduction in cost. 
     Furthermore, since the friction plate  15  and the second holder plate  22  are formed from a steel plate that has a smaller plate thickness than that of the first holder plate  21 , the axial dimension of the torque limiter  4  is reduced, thus contributing to making compact the torque limiter  4 , and consequently the mass ring  3  housing same. 
     Moreover, although the second holder plate  22  has a small plate thickness, it has the first and second side walls  22   a  and  22   c  and the peripheral wall  22   b , that have a plurality of annular bent parts and it is reinforced effectively thereby, and this can impart sufficient strength to the spring holder  5  in cooperation with the first holder plate  21 , which has a large plate thickness, thus contributing to lightening of the weight of the spring holder  5 . 
     Furthermore, since, due to the plurality of centering projections  36  rotatably and axially slidably engaging with the inner peripheral face of the limiter housing  12  being formed integrally with the outer peripheral face of the friction plate  15  so as to be arranged in the peripheral direction, the friction plate  15 , the spring holder  5 , and the hub  13   a  of the driven plate  13  are each centered with respect to the mass ring  3 , when the drive plate  7  joined to the crankshaft  1  is joined to the mass ring  3  during assembly, the crankshaft  1  and the hub  13   a  are coaxially aligned; therefore, the output shaft  2 , which is positioned coaxially with the crankshaft  1 , can easily and appropriately be spline fitted into the hub  13   a , thereby improving the ease of assembly. 
     The present invention is not limited to the above embodiment and may be modified in a variety of ways as long as the modifications do not depart from the spirit and scope thereof.