Torque fluctuation absorbing apparatus

A torque fluctuation absorbing apparatus absorbing a torsional vibration includes a plate member configured to be provided at a power transmission system and including a rolling guide surface, and a mass member rolling on the rolling guide surface of the plate member. The rolling guide surface includes plural first rolling guide surfaces each formed in an arc shape and provided radially inward relative to an outer circumferential portion of the plate member to be arranged in a circumferential direction and a second rolling guide surface allowing the mass member to roll on a locus which is different from a locus on the first rolling guide surface formed in the arc shape. Loci of the mass member are seamlessly switched from the locus in which the mass member rolls on the first rolling guide surface to the locus in which the mass member rolls on the second rolling guide surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2012-189083, filed on Aug. 29, 2012, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure generally relates to a torque fluctuation absorbing apparatus.

BACKGROUND DISCUSSION

A known torque fluctuation absorbing apparatus for absorbing a torsional vibration of a power transmission system is disclosed, for example, in JP2003-65392A (hereinafter referred to as Patent reference 1).

Patent reference 1 discloses a dynamic damper (torque fluctuation absorbing apparatus) which is mounted to a drive shaft (power transmission system) of a compressor and includes a pulley (plate member) having six equally spaced recessed portions in a circumferential direction and six rollers (mass members) housed in the recessed portions, respectively. Each of the recessed portions of the dynamic damper is formed in a substantially semicircular configuration. The dynamic damper disclosed in Patent reference 1 is configured to absorb the torsional vibration of the drive shaft by rolling the rollers in a pendular manner along an arc shaped rolling guide surface formed by an inner surface of the substantially semicircular recessed portion.

According to the dynamic damper (torque fluctuation absorbing apparatus) disclosed in Patent reference 1, in a case where the torsional vibration of the drive shaft (power transmission system) is assumed to be equal to or greater than a predetermined level, a rolling range of the roller (mass member) rolling along the arc shaped roller guide surface is assumed to be greater, which causes a drawback that the roller impacts with, or collides with an end portion of the arc shaped roller guide surface. Thus, according to the dynamic damper disclosed in Patent reference 1, noise is generated because of the roller impacting with the end portion of the roller guide surface when the torsional vibration of the drive shaft is assumed to be equal to or greater than the predetermined level.

A need thus exists for a torque fluctuation absorbing apparatus which is not susceptible to the drawback mentioned above.

SUMMARY

In light of the foregoing, a torque fluctuation absorbing apparatus absorbing a torsional vibration of a power transmission system in response to a torque fluctuation of an engine includes a plate member configured to be provided at the power transmission system and including a rolling guide surface, and a mass member rolling on the rolling guide surface of the plate member. The rolling guide surface includes plural first rolling guide surfaces each formed in an arc shape and provided radially inward relative to an outer circumferential portion of the plate member to be arranged in a circumferential direction and a second rolling guide surface allowing the mass member to roll on a locus which is different from a locus on the first rolling guide surface formed in the arc shape. Loci of the mass member are seamlessly switched from the locus in which the mass member rolls on the first rolling guide surface to the locus in which the mass member rolls on the second rolling guide surface.

DETAILED DESCRIPTION

Embodiments of a torque fluctuation absorbing apparatus will be explained with reference to illustrations of drawing figures as follows.

A construction of a torque fluctuation absorbing apparatus100according to a first embodiment will be explained with reference toFIGS. 1 to 6.

As illustrated inFIG. 1, the torque fluctuation absorbing apparatus100is provided within a housing110aof a transmission110, and is configured to absorb a torsional vibration of a crankshaft (i.e., serving as a power transmission system)120acaused in response to a torque fluctuation of an engine120. More particularly, the torque fluctuation absorbing apparatus100is mounted to a damper130provided within the housing110aof the transmission110, and the damper130is connected to the crankshaft120aof the engine120via an input shaft110b. The damper130is provided to absorb a torsional vibration of the crankshaft120acaused in response to the torque fluctuation of the engine120together with the torque fluctuation absorbing apparatus100. The crankshaft120aserves as an example of a power transmission system. Structures of the torque fluctuation absorbing apparatus100according to the first embodiment will be explained in detail hereinafter.

As illustrated inFIGS. 2 and 3, the torque fluctuation absorbing apparatus100includes a plate member1having a disc shape with hollow (donut shape) and mounted to the crankshaft120a(seeFIG. 1) via the damper130(seeFIG. 1), plural mass members2, and a pair of annular connection members3connecting the plural mass members from one another.

The plate member1made from metal plate member includes a circular hollow portion11penetrating in a plate thickness direction, and an accommodation portion12formed to be annularly recessed along an outer circumferential portion1a. As illustrated inFIGS. 2 to 4, the accommodation portion12is configured to accommodate the plural mass members2therewithin. Further, the accommodation portion12includes a rolling guide surfaces121formed by an inner side surface at the outer circumferential portion1a. The rolling guide surface121is configured to guide the mass member2to roll within the accommodation portion12. More particularly, as illustrated inFIGS. 3 to 5, the rolling guide surface121includes plural arc shaped first rolling guide surfaces121aand plural second rolling guide surfaces121bconnecting the adjacent first rolling guide surfaces121a. The first rolling guide surface121aserves as an example of an outer circumferential side rolling guide surface.

Each of the plural first rolling guide surfaces121aare formed in an arc shape protruding outward in a radial direction of the plate member1. Radius R1of curvature (seeFIG. 5) of the arc shaped first rolling guide surface121ais set at a radius of curvature with which the mass member2is allowed to resonate (i.e., radius of curvature with which the mass member2is likely to roll the most) when rolling on the first rolling guide surface121aat a torsional vibration with a predetermined order (i.e., torsional vibration with a predetermined frequency at which the mass member is likely to roll the most). Thus, by the rolling (resonance) of the mass member2on the first rolling guide surface121a, the torsional vibration with the predetermined order can be absorbed. Further, the plural first rolling guide surfaces121aare formed to be adjacent to one another via the second rolling guide surface121bin a circumferential direction of the plate member1. Further, the plural arc shaped first rolling guide surfaces121aare arranged radially inward relative to the outer circumferential portion1aof the plate member1in a circumferential direction. The plural second rolling guide surfaces121bare provided radially inward relative to the outer circumferential portion1aof the plate member1in the circumferential direction and is configured to roll the mass member2on a locus which is different from a rolling locus of the mass member2on the arc shaped first rolling guide surfaces121a. The plural second rolling guide surfaces121bare configured to guide the mass member2to move to the adjacent first rolling guide surface121awhen the mass member2moves from the first rolling guide surface121ato the adjacent first rolling guide surface121a.

As shown inFIG. 5, the first rolling guide surface121ais formed to have an arc shape with the radius R1of curvature, and the second rolling guide surface121bis formed to have a flat surface. Further, a connection portion121cof the first rolling guide surface121aand the second rolling guide surface121bis formed to have a curved surface so that the first rolling guide surface121awith the arced shape and the second rolling guide surface121bwith the flat surface are smoothly connected.

As illustrated inFIGS. 2 to 4, the accommodation portion12of the plate member1includes plural arc shaped inner circumferential side restriction surfaces122formed at an inner side portion at the inner circumferential side of the plate member1(inner side in a radial direction) provided at radially inward relative to the rolling guide surface121. The plural inner circumferential side restriction surfaces122are arranged in a circumferential direction to restrict the motion of the mass member2in a radially inward direction. More particularly, the inner circumferential side restriction surface122prevents the mass member2from falling (moving) equal to or greater than a predetermined amount (level) when the mass member2falls (moves) inward of the plate member1in a radial direction by a self-weight because the centrifugal force directed towards radially outward of the plate member1is assumed to be smaller when the rotation speed of the crankshaft120abecomes smaller. In a case where the rotation speed of the crankshaft120ais smaller, the plural mass members2integrally fall (move) because the mass members2are connected one another by means of the connection member3. Further, each of the plural inner circumferential side restriction surfaces122is formed in an arc shape protruding radially inward of the plate member1. Still further, as illustrated inFIGS. 4A to 4C, the plural inner circumferential side restriction surfaces122are equally spaced in a manner that each of the inner circumferential side restriction surface122is shifted by a half pitch relative to each of the plural arc shaped first rolling guide surfaces121ain a circumferential direction. That is, the second rolling guide surfaces121barranged between two of the arc shaped first rolling guide surfaces121awhich are adjacent to each other is positioned at a position corresponding to a center of the arc shaped inner circumferential side restriction surface122. Further, the arc shaped inner circumferential side restriction surface122includes a radius of curvature smaller than the radius R of curvature of the first rolling guide surface121a.

As illustrated inFIG. 6, a tapered portion123aprotruding towards the mass member2is formed on an inner bottom surface123of the accommodation portion12of the plate member1. The tapered portion123aincludes a substantially trapezoidal cross-section, and is seamlessly formed in a circumferential direction so as to be annularly formed in a planer view. The tapered portion123ais formed at a portion facing the annular connection member3which connects the plural mass members2. Further, a cover member124for preventing the mass member2from coming out the accommodation portion12is provided at a side opposite from the inner bottom surface123relative to the mass member2accommodated in the accommodation portion12. The cover member124is fixedly provided at the plate member1by means of, for example, a fastening member. Similarly to the inner bottom surface123, a tapered portion124aprotruding towards the mass member2is formed at the cover member124at a portion facing the connection member3. The tapered portion124aincludes a substantially trapezoidal cross-section, and is seamlessly formed in a circumferential direction so as to be annularly formed in a planer view. In those circumstances, alternatively, with a structure in which the mass member2is prevented from coming out from the accommodation portion12by a member provided adjacent to the torque fluctuation absorbing apparatus100(e.g., flywheel), the cover member124is not necessarily provided.

The mass member2made from a metal member is formed in a columnar configuration as illustrated inFIGS. 2 to 4C. As illustrated inFIGS. 3, 4A, 4B, 4C, and 6, the mass member2includes a cylindrical rolling surface21formed with an outer peripheral surface thereof. The mass member2is accommodated within the accommodation portion12in a manner that the rolling surface21faces the rolling guide surface121. The rolling surface21is guided by the rolling guide surface121to roll the mass member2. Further, as illustrated inFIG. 6, an anti-skid member21ais attached onto the rolling surface21so as to cover an outer periphery portion of the mass member2. The anti-skid member21ais made of resin (e.g., Nylon 6 or polycaprolactam (PA6), Nylon 66 (PA66)) and is provided to restrain the mass member2from skidding relative to the rolling guide surface121. Further, as illustrated inFIGS. 2, 3, 4A, 4B, 4C, and 6, a protrusion portion221is formed on the mass member2at each of opposite surfaces22which are arranged orthogonal to the rolling surface21of the mass member2. The protrusion portion221is cylindrically formed and is positioned at a center of a circular side surface22. The protrusion portion221serves as an example of a first engagement portion.

As illustrated inFIGS. 3 and 6, the annular connection members3serving as a pair are arranged to sandwich the mass member2at the opposite surfaces22. Further, as illustrated inFIGS. 2, 4A, 4B, and 4C, the connection member3connects the plural mass members2while retaining, or maintaining a state where the mass members2are equally spaced in a circumferential direction with a predetermined distance. Particularly, as illustrated inFIGS. 3, 4A, 4B, 4C, and 6, the connection member3includes plural hole portions31each of which is formed in an oblong, or oval shape (track shape) and to each of which the protrusion portion221of the mass member2is inserted to be engaged. The hole portion31serves as an example of a second engagement portion. The plural hole portions31are equally spaced in a circumferential direction and are formed penetrating through the connection member3in a plate-thickness direction. Further, the hole portion31which is formed in an oblong, or oval shape is formed extending in a radial direction of the plate member1. The protrusion portion221of the mass member2is engaged with the hole portion31in a manner that the protrusion portion221is movable in a radial direction. More particularly, the oblong, or oval shaped hole portion31allows the mass member2to move in a radial direction when the mass member2rolls at the first rolling guide surface121ain a pendular manner. Further, the hole portion31allows the mass member2to move radially inward while avoiding the protrusion portion221of the mass member2from contacting a radially inner end portion of the hole portion31and avoiding the mass member2from contacting the inner circumferential side restriction surfaces122.

The connection member3is made of resin (e.g., polyacetal) which excels in heat resistance and in abrasion resistance, and thus generation of a noise because of collision of the protrusion portion221of the mass member2with the hole portion31of the connection member3can be reduced compared to a construction in which the connection member3is made of metal. Further, as illustrated inFIG. 6, the connection member3includes a plate thickness which is greater than a protruding height of the protrusion portion221so that the protrusion portion221of the mass member2positioned in the hole portion31does not contact the inner bottom surface123of the plate member1and the cover member124.

According to the torque fluctuation absorbing apparatus100of the first embodiment, the torsional vibration with the predetermined order of the crankshaft120ais absorbed by the resonance caused by the rolling motion of the plural mass members2on the respective first rolling guide surfaces121aof the plate member1in a pendular manner. Further, according to the torque fluctuation absorbing apparatus100, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than a predetermined level, loci of the mass member2are seamlessly switched from a locus in which the mass member2rolls on the first rolling guide surface121ato a locus in which the mass member2rolls on the second rolling guide surface121b. Further, the torque fluctuation absorbing apparatus100is configured to further seamlessly switch the loci from the locus in which the mass member2rolls on the second rolling guide surface121bto the locus in which the mass member2rolls on the first rolling guide surface121aafter seamlessly switching the loci from the locus in which the mass member2rolls on the first rolling guide surface121ato the locus in which the mass member2rolls on the second rolling guide surface121b. That is, as illustrated inFIGS. 4A to 4C, the mass member2rolls on the first rolling guide surface121ain a pendular manner when the torsional vibration of the crankshaft120ais less than the predetermined level, and when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the mass member2moves from the first rolling guide surface121ato the adjacent first rolling guide surface121avia the second rolling guide surface121b.

Hereinafter, a rolling locus of the mass member2of the torque fluctuation absorbing apparatus100according to the first embodiment will be explained with reference toFIGS. 4an5.

In a case where the torsional vibration of the crankshaft120ais less than the predetermined level, the mass member2rolls on the first rolling guide surface121ain a pendular manner to absorb the torsional vibration with the predetermined order. When the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, as illustrated inFIGS. 4A and 4B, the rolling range of the mass member2at the first rolling guide surface121ais assumed to be greater so that the mass member2moves to the second rolling guide surface121b. The plural mass members2move while retaining the predetermined distance from one another by means of the connection member3. Further, at the second rolling guide surface121b, the mass member2is allowed to move radially inward of the plate member1while avoiding the protrusion portion221from contacting the inner end portion of the hole portion31of the connection member3. In those circumstances, the inward motion of the mass member2is restricted so that the mass member2does not contact the inner circumferential side restriction surface122. Thus, the mass member2rolls on a locus which does not largely move, or shift inwardly in a radial direction of the plate member1when rolling on the second rolling guide surface121b. Further, because the first rolling guide surface121aand the second rolling guide surface121bare smoothly connected by the connection portion121c(seeFIG. 5) with curved surface, the mass member2smoothly moves from the first rolling guide surface121ato the second rolling guide surface121b.

Then, the mass member2rolls on the second rolling guide surface121bwith flat surface to move to the adjacent first rolling guide surface121a. In those circumstances, because the second rolling guide surface121band the adjacent first rolling guide surface121aare smoothly connected by the connection portion121cwith curved surface, the mass member2smoothly moves from the second rolling guide surface121bto the adjacent first rolling guide surface121a. That is, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the rolling loci of the mass member2are seamlessly, or continuously switched from the locus in which the mass member2rolls on the first rolling guide surface121ato the locus in which the mass member2rolls on the second rolling guide surface121b, and are further seamlessly, or continuously switched from the locus in which the mass member2rolls on the second rolling guide surface121bto the locus in which the mass member2rolls on the first rolling guide surface121a. Further, during a period that the mass member2moves from the first rolling guide surface121ato the adjacent first rolling guide surface121avia the second rolling guide surface121b, the mass member2is constantly in contact with the rolling guide surface121(first and second rolling guide surfaces121a,121b) to roll thereon and does not come in contact with the inner circumferential side restriction surface122. Still further, the mass member2repeats the rolling motion from the first rolling guide surface121ato the adjacent first rolling guide surface121avia the second rolling guide surface121buntil the torsional vibration of the crankshaft120ais assumed to be less than the predetermined level.

According to the first embodiment, because the rolling loci of the mass member2can be smoothly transited from the locus in which the mass member2rolls on the first rolling guide surface121ato the second rolling guide surface121bby configuring that the loci of the mass member2are seamlessly, or continuously switched from the locus in which the mass member2rolls on the first rolling guide surface121aformed in an arced shape to the locus in which the mass member2rolls on the second rolling guide surface121bwhich is different from the locus in which the mass member2rolls on the first rolling guide surface121a, even when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the mass member2of the embodiment does not collide with an end portion of the rolling guide surface and a stopper member restricting a moving range of the mass member2. Thus, even when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the generation of the noise because of the collision of the mass member2can be restrained.

According to the construction in which the loci of the mass member2are seamlessly, or continuously switched from the locus in which the mass member2rolls on the first rolling guide surface121awhich is formed in an arced shape to the locus in which the mass member2rolls on the second rolling guide surface121bwhich is different from the first rolling guide surface121awhen the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, provided that the locus of the mass member2rolling on the second rolling guide surface121bis set to be linear or curved line which does not largely move, or shift radially inward of the plate member1, the mass member2is restrained from largely moving, or shifting radially inward of the plate member1after the loci of the mass member2are switched from the locus in which the mass member2rolls on the first rolling guide surface121ato the locus in which the mass member2rolls on the second rolling guide surface121b. In those circumstances, because a moving range of the mass member2in a radial direction of the plate member1can be restrained, the torque fluctuation absorbing apparatus100can be downsized by that level, and thus, in consequence, the generation of the noise because of the collision of the mass member2when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level can be restrained while downsizing the torque fluctuation absorbing apparatus100.

Further, according to the first embodiment, the loci of the mass member2are switched in a manner that the locus of the mass member2is further seamlessly, or continuously switched from the locus in which the mass member2rolls on the second rolling guide surface121bto the locus in which the mass member2rolls on the first rolling guide surface121aafter the loci of the mass member2are seamlessly, or continuously switched from the locus in which the mass member2rolls on the first rolling guide surface121ato the locus in which the mass member2rolls on the second rolling guide surface121b. Thus, in addition to seamlessly, or continuously switching the locus in which the mass member2rolls on the first rolling guide surface121ato the locus in which the mass member2rolls on the second rolling guide surface121b, because the loci are seamlessly, or continuously switched from the locus in which the mass member2rolls on the second rolling guide surface121bto the locus in which the mass member2rolls on the first rolling guide surface121a, the rolling locus of the mass member2can be smoothly transited in either cases where the rolling loci of the mass member2are switched from the locus in which the mass member2rolls on the first rolling guide surface121ato the second rolling guide surface121band where the rolling loci of the mass member2are switched from the locus in which the mass member2rolls on the second rolling guide surface121bto the locus in which the mass member2rolls on the first rolling guide surface121a. In consequence, even when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the generation of the noise, for example, by the collision of the mass member2with the end portion of the rolling guide surface and the stopper member can be further restrained.

Further, even when the rolling loci of the mass member2are changed from the locus in which the mass member2rolls on the first rolling guide surface121ato the locus in which the mass member2rolls on the second rolling guide surface121bin a case where the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the loci can be returned from the locus in which the mass member2rolls on the second rolling guide surface121bto the locus in which the mass member2rolls on the first rolling guide surface121areadily, thus, the torsional vibration of the crankshaft120acan be absorbed by the rolling of the mass member2returning to the first rolling guide surface121a.

According to the first embodiment, the plural first rolling guide surfaces121awhich are formed in arced shape of the plate member1are arranged to adjacent one another in a circumferential direction via the second rolling guide surface121b, and when the torsional vibration of the crankshaft120abecomes equal to or greater than the predetermined level, the mass member2moves to the adjacent first rolling guide surface121avia the second rolling guide surface121b. Accordingly, because the mass member2moves from the first rolling guide surface121ato the adjacent first rolling guide surface121ain the circumferential direction via the second rolling guide surface121bwhen the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the mass member2is moved while retaining, or maintaining a contact with the first rolling guide surface121a, the second rolling guide surface121b, and the adjacent first rolling guide surface121aalong the circumference direction of the plate member1. In consequence, even when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the mass member2is effectively restrained from largely moving, or shifting inward in a radial direction of the plate member1.

Further, according to the first embodiment, the plural arc shaped first rolling guide surfaces121awhich adjacent to one another in a circumferential direction are provided at an outer peripheral side of the plate member1, the second rolling guide surface121bis provided to connect the first rolling guide surfaces121awhich are adjacent each other, and the mass member2is guided to move to the adjacent first rolling guide surface121awhen the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level. Thus, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the mass member2is guided by the second rolling guide surface121bto smoothly move to the adjacent first rolling guide surface121a.

Further, according to the first embodiment, the plural arc shaped inner circumferential side restriction surfaces122arranged in a circumferential direction for restricting the motion of the mass member2in a radial direction can be provided at a radially inner side of the plate member1relative to the first rolling guide surface121a. Accordingly, because the inner circumferential side restriction surface122restricts the mass member2from moving radially inward of the plate member1even when the mass member2falls (moves) inward of the plate member1in a radial direction by a self-weight because the centrifugal force directed towards radially outward of the plate member1is assumed to be smaller when the rotation speed of the crankshaft120abecomes smaller, an increase of the moving range of the mass member2in a radial direction of the plate member1can be restrained.

Further, according to the first embodiment, the inner circumferential side restriction surface122is shifted by a half pitch relative to the first rolling guide surface121ain a circumferential direction. According to the foregoing construction, because a distance in a radial direction of the plate member1between the first rolling guide surface121aand the inner circumferential side restriction surface122is prevented from being partially excessively increased, a partial excessive increase of a falling distance (moving distance) of the mass member2when falling (moving) radially inward of the plate member1can be restrained. Accordingly, even when the mass member2falls, or moves to collide with the inner circumferential side restriction surface122(i.e., the motion of the mass member2is restricted), the noise caused by the collision can be reduced by the level of the shortened falling distance.

Further, according to the first embodiment, the annular connection member3connects the plural mass members2while retaining a state where the plural mass members2are equally spaced keeping a predetermined distance from one another. Thus, even when the mass member2moves from the first rolling guide surface121ato the adjacent first rolling guide surface121avia the second rolling guide surface121b, because the distances between the mass members2are retained by the connection member3, a contact, or collision of the adjacent mass members2can be prevented. Accordingly, the generation of the noise because of the collision is restrained.

Further, by connecting plural mass members by means of the annular connection member3, because the plural mass members2arranged in a circumferential direction can be connected as a bunch by the single connection member3, an increase in the number of parts can be restrained compared to a structure in which separate connection members are provided between respective adjacent mass members2. Further, because the adjacent mass members2are connected in a state where the mass members2are spaced keeping a small distance, or an interval from one another and the small distance can be retained, compared to a structure in which the connection member3is not provided, the distance, or interval between the adjacent mass members2can be reduced. Because the greater number of the mass members2can be provided according to the foregoing construction, accordingly, torsional vibration absorbing effects can be enhanced.

Further, according to the first embodiment, the protrusion portion221is provided at each of the plural mass members2, and the hole portions31to each of which each of the protrusion portions221of the plural mass members2engages to be movable in a radial direction of the plate member1are provided at the connection member3. Thus, with a simple construction of the protrusion portion221and the hole portion31, the distance, or interval between the mass members2can be retained while allowing the mass member2to move in a radial direction of the plate member1when the mass member2rolls.

Further, according to the first embodiment, the tapered portion123ais formed at the portion where the connection member3and the plate member1face each other. Thus, because an area of contact of the connection member3and the plate member1can be reduced, hysteresis loss caused by the sliding resistance between the connection member3and the plate member1can be reduced.

According to the first embodiment, the second rolling guide surface121bis formed to have a flat surface. Thus, compared to a structure in which the second rolling guide surface121bis formed to protrude radially inward of the plate member1, because the moving amount of the mass member2moving radially inward against the centrifugal force when rolling on, or passing or crossing the second rolling guide surface121bcan be reduced, the mass member2can be more readily moved to the adjacent first rolling guide surface121avia the second rolling guide surface121b.

Further, according to the first embodiment, the anti-skid member21ais provided to cover the outer periphery of the mass member2. Accordingly, because the anti-skid member21arestrains the mass member2from slipping when rolling on the first rolling guide surface121a, the subject torsional vibration with the predetermined order can be effectively absorbed.

First to seventh modified examples of the first embodiment will be explained as follows. As illustrated inFIG. 6, according to the first embodiment, the tapered portion123aand the tapered portion124aprotruding towards the mass member2are formed at the inner bottom surface123of the accommodation portion12of the plate member1and the cover member124, respectively. However, the construction may be modified as the first to fifth modified examples illustrated inFIGS. 7A to 7E, respectively.

More particularly, according to the first modified example illustrated inFIG. 7A, a tapered portion103bprotruding towards a plate member101a(cover member124b) is formed at a connection member103aat a portion facing the plate member101a(cover member124b). Further, according to the second modified example illustrated inFIG. 7B, a tapered portion103dwhich is recessed towards the mass member2is formed at a connection member103cat a portion facing the plate member101a(cover member124b). Further, according to a third modified example illustrated inFIG. 7C, a protrusion portion103fprotruding towards the plate member101a(cover member124b) is formed at a connection member103eat a portion facing the plate member101a(cover member124b). Still further, according to a fourth modified example illustrated inFIG. 7D, a tapered portion123cand a tapered portion124dwhich are recessed in opposite directions from the mass member2are formed at an inner bottom surface123bof the accommodation portion12of a plate member101band a cover member124c, respectively. Further, according to the fifth modified example illustrated inFIG. 7E, a protrusion portion123eand a protrusion portion124fwhich protrude towards the mass member2are formed at an inner bottom surface123dof the accommodation portion12of a plate member101cand a cover member124e, respectively.

Further, whereas the second rolling guide surface121bis formed to have a flat surface according to the first embodiment, alternatively, according to the sixth modified example of the first embodiment illustrated inFIG. 8, a second rolling guide surface121dis formed in an arced shape with a radius R2of curvature which is smaller than the radius R1of curvature of the first rolling guide surface121a. In those circumstances, the second rolling guide surface121dis formed in an arced shape protruding radially inward of the plate member. Further, a connection portion121eof the first rolling guide surface121aand the second rolling guide surface121dis formed with a curved surface so as to smoothly connect the first rolling guide surface121awhich is in the arced shape and the second rolling guide surface121dwhich is in the arced shape which protrude in an opposite direction to the protruding direction of the first rolling guide surface121a.

Further, whereas the connection member3and the mass member2are separately provided according to the first embodiment, alternatively, according to the seventh modified example of the first embodiment illustrated inFIG. 9, a pair of annular connection members103gand a mass member2aare integrally formed. Particularly, a clinching portion221bis formed by clinching a tip end portion of a protrusion portion221ain a state where the protrusion portion221aof the mass member2ais positioned, or inserted in the hole portion131of a connection member103g. The clinching portion221bprevents the connection member103gfrom falling, or disengaging from the mass member2aand integrally forms the mass member2aand the connection member103g. Accordingly, because the plural mass members2aand the annular connection members103gserving as a pair can be formed as one unit (i.e., as a sub-assembly), assembling workability, or assembling performance of the torque fluctuation absorbing apparatus can be enhanced. In those circumstances, the hole portion131serves as an example of a second engagement portion, and the protrusion portion221aserves as an example of a first engagement portion.

A torque fluctuation absorbing apparatus200according to a second embodiment of the disclosure will be explained with reference toFIGS. 10 to 14. According to the second embodiment, a second rolling guide surface215b(i.e., serving as a rolling guide surface) is configured so that a mass member202rolls thereon with a smaller turning radius compared to on an arc shaped first rolling guide surface215a(i.e., serving as a rolling guide surface).

As illustrated inFIGS. 10 to 12, the torque fluctuation absorbing apparatus200according to the second embodiment includes a plate member201which is formed in a disc shape with hollow (donut shape) and mounted to the crankshaft120a(seeFIG. 1) via the damper130(seeFIG. 1), and plural mass members202.

The plate member201made from a metal member formed in a plate shape includes a hollow portion211formed in a disc shape penetrating through in a plate thickness direction. Further, as illustrated inFIGS. 10, 11, and 13, a first recessed portion212(i.e., serving as a recessed portion) including an inner side surface configuration in which plural arcs are continuously arranged in a circumferential direction is formed at a first surface201aof the plate member201. Similarly, a second recessed portion213(i.e., serving as a recessed portion) including an inner side surface configuration in which plural arcs are continuously arranged in a circumferential direction is formed at a second surface201bof the plate member201. The first recessed portion212and the second recessed portion213serve as examples of a recessed portion. Further, as illustrated inFIGS. 11 to 13, the plate member201includes plural elliptical rolling guide hole214which penetrated through in a plate thickness direction. Further, the plate member201includes a rolling guide surface215for guiding the mass member202to roll. The rolling guide surface215includes plural arc shaped first rolling guide surfaces215awhich are configured with an inner surface of the first recessed portion212(second recessed portion213) and plural elliptical second rolling guide surfaces215bconfigured with an inner surface of the plural rolling guide holes214.

The plural first rolling guide surfaces215aare provided in a circumferential direction at radially inward relative to an outer peripheral portion201cof the plate member201so that the mass member202rolls thereon. Further, the plural first rolling guide surfaces215aare formed in an arc shape protruding radially outward of the plate member201. Still further, the second rolling guide surface215bis provided separately from the first rolling guide surface215aand is formed so that the mass member202rolls thereon on a locus which is different from a locus on the arc shaped first rolling guide surface215a. In those circumstances, the second rolling guide surface215bguides the mass member202to roll while restricting the motion of the mass member202towards radially inward (towards inner circumference) of the plate member201. More particularly, the second rolling guide surface215bis formed in a manner that the mass member202rolls thereon with a turning radius smaller than a turning radius on the arc shaped first rolling guide surface215a. Further, the elliptical second rolling guide surface215bis formed to be elongated in a circumferential direction of the plate member201and is formed to be shorter in a radial direction of the plate member201. That is, the elliptical second rolling guide surface215bis arranged so that a semi-minor axis is positioned along a radial direction of the plate member201and a semi-major axis is positioned along a direction perpendicular to the radial direction of the plate member201.

As illustrated inFIGS. 11 and 13, the mass member202includes a disc shaped first mass member portion202apositioned at the first surface201aof the plate member201, a disc shaped second mass member portion202bpositioned at the second surface201bof the plate member201, and a rolling shaft portion202cconnecting the first mass member portion202aand the second mass member portion202b. The first mass member portion202aand the second mass member portion202bserve as a first mass member and a second mass member, respectively.

The first mass member portion202aand the second mass member portion202bare made of metal. The first mass member portion202ais positioned inside the first recessed portion212of the plate member201and includes a first outer periphery rolling portion202drolling on the first rolling guide surface215aof the first recessed portion212. Further, the second mass member portion202bis positioned inside the second recessed portion213of the plate member201and includes a second outer periphery rolling portion202erolling on the first rolling guide surface215aof the second recessed portion213. The first outer periphery rolling portion202dand the second outer periphery rolling portion202eare formed in the same configuration (i.e., circumference length and thickness are the same). The first outer periphery rolling portion202dand the second outer periphery rolling portion202eserve as examples of an outer periphery rolling portion. Further, as illustrated inFIGS. 11 and 14, the first mass member portion202ais formed with a through hole202fin which the rolling shaft portion202cis inserted. Still further, as illustrated inFIG. 14, an enlarged diameter portion202gwhose inner diameter is enlarged is formed at an end portion of the through hole202fpositioned at a side opposite from a side where the second mass member portion202bis positioned.

As illustrated inFIGS. 13 and 14, a portion of the first mass member portion202a(second mass member portion202b) which faces the plate member201may be formed in a flat shape, however, in order to reduce a resistance when rolling, a tapered portion202h(tapered portion202i) protruding towards the plate member201is formed. The tapered portion202h(tapered portion202i) is formed in a frustum of cone, or circular truncated cone. As illustrated inFIG. 13, an anti-skid member21bis attached to the first outer periphery rolling portion202d(second outer periphery rolling portion202e) of the first mass member portion202a(second mass member portion202b) for covering an outer periphery of the first mass member portion202a(second mass member portion202b). The anti-skid member21bmade of resin (e.g., Nylon 6 or polycaprolactam (PA6), Nylon 66 (PA66)) is provided to restrain the first mass member portion202a(second mass member portion202b) from slipping relative to the first rolling guide surface215a. Further, a surface of the first mass member portion202a(second mass member portion202b) at a side opposite from the side facing the plate member201is formed to be flush with the first surface201a(second surface201b) of the plate member201in a state where the first mass member portion202a(second mass member portion202b) is positioned at the first recessed portion212(second recessed portion213).

The rolling shaft portion202cmade of metal is fixedly provided at the second mass member portion202bas illustrated inFIGS. 11 to 14. Further, the rolling shaft portion202cincludes a smaller diameter compared to a diameter of the first outer periphery rolling portion202d(second outer periphery rolling portion202e). Further, the rolling shaft portion202cis configured to roll on the elliptical second rolling guide surface215bformed by an inner surface of the rolling guide hole214in a state where the rolling shaft portion202cis positioned in the rolling guide hole214of the plate member201when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than a predetermined level. Further, as illustrated inFIG. 14, a stepped portion202jwhose diameter is smaller is formed at the rolling shaft portion202cso that a diameter of the rolling shaft portion202cat a tip end portion is assumed to be smaller than a diameter at a base portion.

Further, the rolling shaft portion202cis constructed to form a clinching portion202kby clinching a tip end portion of the rolling shaft portion202cin a state where the rolling shaft portion202cis positioned in the through hole202fof the first mass member portion202a. More particularly, the clinching portion202kis formed by inserting the rolling shaft portion202cinto the through hole202fof the first mass member portion202apositioned at the first surface201aof the plate member201and by clinch processing in a state where the rolling shaft portion202cis inserted from the second surface201bside of the plate member201to be positioned in the rolling guide hole214(seeFIG. 13). Accordingly, the first mass member portion202aand the second mass member portion202bare fixedly connected by the rolling shaft portion202cpositioned at the rolling guide hole214in a state where the first mass member portion202aand the second mass member portion202bare arranged at the side of the first surface201aof the plate member201and at the side of the second surface201bof the plate member201, respectively. Further, upon a contact of the first mass member portion202ato the stepped portion202jof the rolling shaft portion202c, the first mass member portion202aand the second mass member portion202bare connected by the rolling shaft portion202cwhile keeping a predetermined distance from one another. The predetermined distance between the first mass member portion202aand the second mass member portion202bis slightly longer than a plate thickness of a portion of the plate member201corresponding to a distance between the bottom surfaces of the first recessed portion212and the second recessed portion213. Further, the clinching portion202kof the rolling shaft portion202cis housed within the enlarged diameter portion202gof the first mass member portion202ato be flush with the first mass member portion202a.

As illustrated inFIG. 13, a noise reduction member21cmade of resin (e.g., Nylon 6 or polycaprolactam (PA6), Nylon 66 (PA66)) is attached to the rolling shaft portion202cto cover the outer periphery of the rolling shaft portion202c. The noise reduction member21cis provided to reduce the generation of the noise because of a collision of the rolling shaft portion202cand the second rolling guide surface215bin a case where the mass member202falls (moves) radially inward of the plate member201by self-weight when the centrifugal force towards the radially outer side of the plate member201is reduced due to lower rotation speed of the crankshaft120a.

With the foregoing construction, the torque fluctuation absorbing apparatus200according to the second embodiment is configured to absorb the torsional vibration with the predetermined order of the crankshaft120aby rolling the plural mass members202on the first rolling guide surface215aof the plate member201in a pendular manner to resonate. Further, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the loci of the mass member202is continuously, or seamlessly switched from a locus in which the mass member202rolls on the first rolling guide surface215ato a locus in which the mass member202rolls on the second rolling guide surface215b. Further, the torque fluctuation absorbing apparatus200is configured to further switch loci of the mass member202seamlessly, or continuously from the locus in which the mass member202rolls on the second rolling guide surface215bto the locus in which the mass member202rolls on the first rolling guide surface215aafter seamlessly, or continuously switching the loci of the mass member202from the locus in which the mass member202rolls on the first rolling guide surface215ato the locus in which the mass member202rolls on the second rolling guide surface215b.

A rolling locus of the mass member202of the torque fluctuation absorbing apparatus200according to the second embodiment will be explained hereinafter with reference toFIG. 12.

When the level of the torsional vibration of the crankshaft120ais lower than a predetermined level, the first outer periphery rolling portion202d(second outer periphery rolling portion202e(seeFIG. 13)) rolls in a pendular manner along the first rolling guide surface215ain a state where the first mass member portion202a(second mass member portion202b(seeFIG. 13)) of the mass member202is positioned at the first recessed portion212(second recessed portion213) of the plate member201. More particularly, when the level of the torsional vibration of the crankshaft120ais lower than the predetermined level, the mass member202rolls along the first rolling guide surface215ain a pendular manner within a range between a position indicated with (b) inFIG. 12at which the mass member202is moved by a predetermined angle α (e.g., 30 degrees) in a clockwise direction from a position indicated with (a) inFIG. 12where the mass member202is positioned at an outermost position in a radial direction of the plate member201and a position indicated with (c) inFIG. 12at which the mass member202is moved by a predetermined angle α (e.g., 30 degrees) in a counterclockwise direction (i.e., predetermined angle −α) from the position indicated with (a) inFIG. 12. That is, when the level of the torsional vibration of the crankshaft120ais lower than the predetermined level, the mass member202rolls along the first rolling guide surface215ain a pendular manner within the range between the position indicated with (b) and the position indicated with (c) inFIG. 12with the position indicated with (a) as a substantial center. In those circumstances, the mass member202absorbs the torsional vibration with the predetermined order of the crankshaft120aby rolling in a pendular manner without the rolling shaft portion202ccontacting the second rolling guide surface215bformed at an inner surface of the rolling guide hole214of the plate member201. The foregoing predetermined angle (predetermined angles α, −α, corresponding to, for example, 30 degrees, −30 degrees) corresponds to a rotation angle (moving angle) of the mass member202in a case where a center O of the arc shaped first rolling guide surface215ais defined as a reference.

On the other hand, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the rolling shaft portion202cof the mass member202rolls along the inner surface of the rolling guide hole214which structures the second rolling guide surface215b. More particularly, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the rolling range of the mass member202increases to move in a clockwise direction exceeding a position which is a predetermined angle α (i.e., position (b) inFIG. 12) from the position (a) shown inFIG. 12. In those circumstances, the rolling loci of the mass member202continuously, or seamlessly switch from a locus in which the first outer periphery rolling portion202d(second outer periphery rolling portion202e(seeFIG. 13)) rolls on the first rolling guide surface215ato a locus in which the rolling shaft portion202crolls on the second rolling guide surface215b. Then, by the rolling motion of the rolling shaft portion202crolling along the second rolling guide surface215b, the mass member202reaches the position (c) via the positions (d), (e), (f), (g), and (h) in the mentioned order in the clockwise direction from the position (b) inFIG. 12. After passing the position (b) inFIG. 12until reaching the position (c), the mass member202rolls without the first outer periphery rolling portion202d(second outer periphery rolling portion202e(seeFIG. 13)) contacting the first rolling guide surface215a. In those circumstances, the mass member202rolls on a locus with smaller turning radius by the second rolling guide surface215bcompared to on a locus when rolling on the arc shaped first rolling guide surface215a.

Thereafter, the rolling loci of the mass member202continuously, or seamlessly switch from the locus in which the rolling shaft portion202crolls on the second rolling guide surface215bto the locus in which the first outer periphery rolling portion202d(second outer periphery rolling portion202e(seeFIG. 13)) rolls on the first rolling guide surface125aat the position (c) inFIG. 12. Then, until the torsional vibration of the crankshaft120ais assumed to be less than the predetermined level, the loci are repeatedly switched between the locus in which the mass member202rolls on the first rolling guide surface215aand the locus in which the mass member202rolls on the second rolling guide surface215b. Depending on the direction of the torsional vibration of the crankshaft120a, the mass member202may exceed the position which is predetermined angle α in counterclockwise direction (i.e., predetermined angle −α) (i.e., position (c) inFIG. 12) from the position (a) inFIG. 12to reach the position (b) via the positions (h), (g), (f), (e), and (d) in the mentioned order in the counterclockwise direction inFIG. 12. Even in those circumstances, the rolling loci of the mass member202switch seamlessly, or continuously.

Other constructions of the second embodiment are common to the first embodiment.

According to the second embodiment, as described above, the second rolling guide surface215bis formed so that the mass member202rolls on the second rolling guide surface215bwith smaller turning radius compared to a case where the mass member202rolls on the arc shaped first rolling guide surface215a. Thus, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the rolling loci of the mass member202can be seamlessly, or continuously switched from the locus in which the mass member202rolls on the first rolling guide surface215ato the locus in which the mass member202rolls on the second rolling guide surface215bwith smaller turning radius compared to on the first rolling guide surface215a, thus, the mass member202rolls with smaller turning radius when the mass member202moves radially inward of the plate member201. Accordingly, an increase of the moving range of the mass member202in the radial direction of the plate member201can be effectively restrained.

Further, according to the second embodiment, as described above, the mass member202is provided with the first outer periphery rolling portion202d(second outer periphery rolling portion202e) rolling on the first rolling guide surface215aof the plate member201, and the rolling shaft portion202chaving an outer diameter smaller than an outer diameter of the first outer periphery rolling portion202d(second outer periphery rolling portion202e) of the mass member202and rolling on the second rolling guide surface215b. Accordingly, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the rolling loci of the mass member202switch from the locus in which the first outer periphery rolling portion202d(second outer periphery rolling portion202e) rolls on the first rolling guide surface215ato the locus in which the rolling shaft portion202chaving the smaller outer diameter than the first outer periphery rolling portion202d(second outer periphery rolling portion202e) rolls on the second rolling guide surface215bwith smaller turning radius compared to on the first rolling guide surface215a, thus, the mass member202can be rolled readily with smaller turning radius when the mass member202moves radially inward of the plate member201.

Further, according to the second embodiment, as described above, the second rolling guide surface215bis formed by the inner surface of the rolling guide hole214provided penetrating through the plate member201, and the first mass member portion202aand the second mass member portion202bare connected by the rolling shaft portion202cpositioned in the rolling guide hole214in a state where the first mass member portion202aand the second mass member portion202bare positioned at the first side and the second side of the plate member201, respectively. Accordingly, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the rolling shaft portion202cof the mass member202can be readily rolled along the second rolling guide surface215bformed by the inner surface of the rolling guide hole214of the plate member201.

Further, according to the second embodiment, as described above, the first mass member portion202a(second mass member portion202b) is constructed so that the first outer periphery rolling portion202d(second outer periphery rolling portion202e) rolls along the first rolling guide surface215ain a state where the first mass member portion202a(second mass member portion202b) is positioned in the first recessed portion212(second recessed portion213), and when the torsional vibration of the crankshaft210ais assumed to be equal to or greater than the predetermined level, the rolling shaft portion202crolls along the inner surface of the rolling guide hole214constructing the second rolling guide surface215b. Thus, when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the rolling loci of the mass member202can be continuously, or seamlessly transited from the locus in which the first outer periphery rolling portion202d(second outer periphery rolling portion202e) of the first mass member portion202a(second mass member portion202b) rolls on the first rolling guide surface215aof the first recessed portion212(second recessed portion213) to the locus in which the rolling shaft portion202crolls on the second rolling guide surface215bconstructed by the inner surface of the rolling guide hole214.

According to the second embodiment, as described above, the second rolling guide surface215bon which the rolling shaft portion202cof the mass member202rolls is formed in an elliptical shape which is shorter in a radial direction and longer in a circumferential direction of the plate member201. Thus, because the second rolling guide surface215bcan be defined to be shorter in the radial direction of the plate member201, the large motion of the mass member202in a radially inward direction of the plate member201can be more effectively restrained in a case where the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level.

Further, according to the second embodiment, as described above, the tapered portion202h(tapered portion202i) is formed on the mass member202at the portion where the first mass member portion202a(second mass member portion202b) and the plate member201face each other. Thus, because dimensions of an area of contact of the first mass member portion202a(second mass member portion202b) of the mass member202and the plate member201is reduced, hysteresis loss because of the sliding resistance between the first mass member portion202a(second mass member portion202b) of the mass member202and the plate member201can be reduced.

Further, according to the construction of the second embodiment, similar to the first embodiment, because the rolling loci of the mass member202can be smoothly transited from the locus in which the mass member202rolls on the first rolling guide surface215ato the locus in which the mass member202rolls on the second rolling guide surface215bby configuring to continuously, or seamlessly switch the rolling loci of the mass member202from the locus in which the mass member202rolls on the arc shaped first rolling guide surface215ato the locus in which the mass member202rolls on the second rolling guide surface215bwhose locus is different from the locus of the mass member202rolling on the first rolling guide surface215awhen the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level, the generation of the noise due to the collision of the mass member202can be restrained even when the torsional vibration of the crankshaft120ais assumed to be equal to or greater than the predetermined level.

Other effects and advantages of the second embodiment are the same with those of the first embodiment.

First to tenth modified examples of the second embodiment will be explained as follows. According to the second embodiment, as illustrated inFIG. 13, the tapered portion202h(tapered portion202i) protruding towards the plate member201is formed on the first mass member portion202a(second mass member portion202b). Alternatively, constructions according to the first to fifth modified examples of the second embodiment illustrated inFIGS. 15A to 15Emay be applied.

More particularly, according to the first modified example shown inFIG. 15A, a tapered portion301b(tapered portion301c) which is recessed in a frustum of cone shape, or in a circular truncated cone shape is formed on the plate member301aat a portion facing the first mass member portion302a(second mass member portion302b). Further, according to the second modified example illustrated inFIG. 15B, a tapered portion301e(tapered portion301f) protruding towards the first mass member portion302a(second mass member portion302b) in a frustum of cone shape, or in a circular truncated cone shape is formed on the plate member301dat a portion facing the first mass member portion302a(second mass member portion302b). Further, according to the third modified example illustrated inFIG. 15C, a tapered portion302e(tapered portion302f) recessed in a frustum of cone shape, or in a circular truncated cone shape is formed on the first mass member portion302c(second mass member portion302d) at a portion facing the plate member201. Still further, according to the fourth modified example illustrated inFIG. 15D, a protrusion portion302i(protrusion portion302j) protruding towards the plate member201is formed on the first mass member portion302g(second mass member portion302h) at a portion facing the plate member201, the protrusion portion302i(protrusion portion302j) is formed at the position close to the rolling shaft portion202c. Further, according to the fifth modified example illustrated inFIG. 15E, a protrusion portion301h(protrusion portion301i) protruding towards the first mass member portion302a(second mass member portion302b) is formed on the plate member301gat a portion facing the first mass member portion302a(second mass member portion302b). The first mass member portion302a,302c,302gserves as an example of a first mass member. The second mass member portion302b,302d,302hserves as an example of a second mass member.

Further, according to the second embodiment, the rolling guide hole214structuring the second rolling guide surface215bis formed in an elliptical configuration. Alternatively, constructions disclosed in the sixth to ninth modified examples of the second embodiment illustrated inFIGS. 16A to 16Dmay be applied.

Particularly, according to the sixth modified example illustrated inFIG. 16A, by forming a rolling guide hole214ain an oblong, or oval shape (track shape), a second rolling guide surface215cstructured with an inner surface of the rolling guide hole214ais formed in an oblong, or oval shape (track shape). Further, according to the seventh modified example illustrated inFIG. 16B, by forming a rolling guide hole214bin a circular, or ring shape (donut shape), a second rolling guide surface215dstructured by an inner surface of the rolling guide hole214bis formed in an elliptical configuration. Further, according to the eighth modified example illustrated inFIG. 16C, by forming the rolling guide hole214cin a substantially triangular shape (mountain like configuration), the second rolling guide surface215estructured with an inner surface of the rolling guide hole214cis formed in a substantially triangular shape (mountain like shape). Still further, according to the ninth modified example illustrated inFIG. 16D, by forming an inner surface of a rolling guide hole214din a heart like shape (curved oblong shape), a second rolling guide surface215fformed by the inner surface of a rolling guide hole214dis formed in a heart like shape (curved oblong shape).

According to the second embodiment, the second rolling guide surface215bstructured with an inner surface of the rolling guide hole214of the plate member201is provided. Alternatively, according to the tenth modified example of the second embodiment as illustrated inFIG. 17, plural protrusion portions301kformed in columnar shape are formed on a plate member301j, and a second rolling guide surface315a(i.e., serving as a rolling guide surface) is structured with an outer peripheral surface of the protrusion portion301k. In those circumstances, a mass member302kis formed with a through hole3021formed in an elliptical shape to which the protrusion portion301kcan be inserted. Then, when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level, rolling loci of the mass member302kis continuously, or seamlessly switched from a locus in which an outer periphery rolling portion302mof the mass member302krolls on a first rolling guide surface315b(i.e., serving as a rolling guide surface) of the plate member301jto a locus in which an inner surface rolling portion302nstructured with an inner surface of the through hole3021of the mass member302krolls on the second rolling guide surface315astructured with an outer periphery surface of the protrusion portion301kof the plate member301j.

The disclosed embodiments are mere examples and are not limited thereto.

For example, according to the first embodiment, the annular connection members3serving as a pair for connecting the plural mass members2is disclosed, however, the construction is not limited. Alternatively, only single annular connection member may be provided.

Further, according to the first embodiment, the protrusion portion221(first engagement portion) is provided at the mass member2and the hole portion31(second engagement portion) to which the protrusion portion221engages is provided at the connection member3, however, the construction is not limited. Alternatively, a hole portion may be provided at a mass member, and a protrusion portion which engages with the hole portion may be provided at a connection member.

According to the second embodiment, the first mass member portion202a(first mass member) and the second mass member portion202b(second mass member) are provided at the mass member202, however, the construction is not limited. Alternatively, only one of a first mass member portion (first mass member) and a second mass member portion (second mass member) may be provided at a mass member. In those circumstances, a recessed portion having a first rolling guide surface may be provided at only one of a first surface and a second surface of a plate member.

Further, according to first and second embodiments, the torque fluctuation absorbing apparatus is structured to absorb a torsional vibration of the crankshaft of the engine, however, the construction is not limited. Alternatively, a torque fluctuation absorbing apparatus may be constructed to absorb a torsional vibration of a power transmission system other than a crankshaft in response to a torque fluctuation of an engine.

Further, according to the first and second embodiments, the anti-skid member is provided to cover the outer periphery of the mass member, however, the construction is not limited. Alternatively, an anti-skid member may be provided at a rolling guide surface on which a mass member rolls without providing the anti-skid member onto the mass member. Further, alternatively, an anti-skid member may be provided at the both of a mass member and a rolling guide surface on which the mass member rolls.

Further, according to the first and second embodiments, the anti-skid member is made of resin, however, the construction is not limited. Alternatively, an anti-skid member may be made of material other than the resin, for example, the anti-skid member may be made from a rubber member.

According to the construction of the embodiment, the torque fluctuation absorbing apparatus absorbing the torsional vibration of the power transmission system (crankshaft120a) in response to a torque fluctuation of an engine includes the plate member (1,101a,101b,101c,201,301a,301d,301g,301j) configured to be provided at the power transmission system (120a) and including the rolling guide surface (121,215,315a,315b), and the mass member (2,202,302k) rolling on the rolling guide surface (121,215,315b) of the plate member (1,101a,101b,101c,201,301a,301d,301g,301j). The rolling guide surface (121,215,315b) includes plural first rolling guide surfaces (121a,215a,315b) each formed in an arc shape and provided radially inward relative to an outer circumferential portion of the plate member (1,101a,101b,101c,201,301a,301d,301g,301j) to be arranged in a circumferential direction and the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a) allowing the mass member (2,202,302k) to roll on a locus which is different from a locus on the first rolling guide surface (121a,215a,315b) formed in the arc shape. Loci of the mass member (2,202,302k) are seamlessly switched from the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) to the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a)

According to the torque fluctuation absorbing apparatus of the embodiment, when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, loci of the mass member (2,202,302k) are seamlessly switched from the locus in which the mass member (2,202,302k) rolls on the arc shaped first rolling guide surface (121a,215a,315b) to the locus, in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a), which is different from the first rolling guide surface (121a,215a,315b) to allow smooth transition of the rolling locus of the mass member (2,202,302k) from the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) to the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a). Thus, even when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, the mass member (2,202,302k) does not come to collide with an end portion of the rolling guide surface and a stopper member which restricts a moving range of the mass member (2,202,302k). Accordingly, even when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, generation of noise because of collisions of the mass member (2,202,302k) can be restrained.

According to the construction of the embodiment, the loci of the mass member (2,202,302k) are further seamlessly switched from the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a) to the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) after seamlessly switching from the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) to the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a).

According to the construction of the embodiment, in addition to seamlessly switching the loci of the mass member (2,202,302k) from the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) to the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a), because the loci of the mass member (2,202,302k) is seamlessly switched from the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a) to the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b), the rolling locus of the mass member (2,202,302k) can be smoothly transited in either cases where the rolling loci of the mass member (2,202,302k) are switched from the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) to the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface, and where the rolling loci of the mass member (2,202,302k) are switched from the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a) to the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b). In consequence, even when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, generation of the noise because of the collisions of the mass member (2,202,302k) with an end portion of the rolling guide surface and a stopper member can be further restrained. Further, because the loci can be readily returned from the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a) to the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) even when the rolling loci of the mass member (2,202,302k) transit from the locus in which the mass member (2,202,302k) rolls on the first rolling guide surface (121a,215a,315b) to the locus in which the mass member (2,202,302k) rolls on the second rolling guide surface (121b,121d,215b,215c,215d,215e,215f,315a) when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, the torsional vibration of the power transmission system (crankshaft120a) can be absorbed by the rolling of the mass member (2,202,302k) returning to the first rolling guide surface.

According to the construction of the embodiment, the plural first rolling guide surfaces (121a) each formed in the arc shape of the plate member (1,101a,101b,101c) are formed to be adjacent to one another in a circumferential direction via the second rolling guide surface (121b,121d). The mass member (2) moves to the adjacent first rolling guide surface (121a) via the second rolling guide surface (121b,121d) when a torsional vibration of the power transmission system (120a) is assumed to be equal to or greater than a predetermined level.

According to the construction of the embodiment, when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, the mass member (2) moves from the first rolling guide surface (121a) to the adjacent first rolling guide surface (121a) via the second rolling guide surface (121b,121d) in a circumferential direction, thus allowing the mass member (2) to move in a circumferential direction of the plate member (1,101a,101b,101c) while the mass member (2) being in contact with the first rolling guide surface (121a), the second rolling guide surface (121b,121d), and the adjacent first rolling guide surface (121a). In consequence, even when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, large motion, or shift of the mass member (2) in a radially inward direction of the plate member (1,101a,101b,101c) can be effectively restrained.

According to the construction of the embodiment, the plural first rolling guide surfaces (121a) include the plural arc shaped outer periphery side rolling guide surfaces (121a) arranged adjacent to one another in a circumferential direction at an outer periphery portion of the plate member (1,101a,101b,101c). The second rolling guide surface (121b,121d) is provided to connect the first rolling guide surfaces (121a) adjacent to each other and is configured to guide the mass member (2) to move to the adjacent outer periphery side rolling guide surface (121a) when the torsional vibration of the power transmission system (120a) is assumed to be equal to or greater than the predetermined level.

According to the construction of the embodiment, when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, the mass member (2) is guided by the second rolling guide surface (121b,121d) to smoothly move to the first rolling guide surface (121a).

According to the construction of the embodiment, the plate member (1,101a,101b,101c) includes the plural arc shaped inner circumferential side restriction surfaces (122) provided at an inner circumferential portion of the plate member (1,101a,101b,101c) provided radially inward relative to the outer periphery side rolling guide surface (121a), the inner circumferential side restriction surfaces (122) arranged in a circumferential direction and restricting the mass member (2) from moving in a radially inward direction.

According to the construction of the embodiment, even when the mass member (2) falls (moves) radially inward of the plate member (1,101a,101b,101c) by a self-weight because the centrifugal force directed towards radially outward of the plate member (1,101a,101b,101c) is assumed to be smaller when the rotation speed of the power transmission system (crankshaft120a) becomes smaller, because the inner circumferential side restriction surface (122) prevents the mass member (2) from moving in a radially inward of the plate member (1,101a,101b,101c), an increase in a moving range of the mass member (2) can be restrained in a radial direction of the plate member (1,101a,101b,101c).

According to the construction of the embodiment, each of the inner circumferential side restriction surfaces (122) and each of the outer periphery side rolling guide surfaces are (121a) shifted by a half pitch relative to each other in a circumferential direction.

According to the construction of the embodiment, because a distance in a radial direction of the plate member (1,101a,101b,101c) between the outer periphery side rolling guide surface (121a) and the inner circumferential side restriction surface (122) is prevented from being partially excessively increased, a partial excessive increase of a falling distance of the mass member (2) when falling (moving) radially inward of the plate member (1,101a,101b,101c) can be restrained. Accordingly, even when the mass member (2) falls to collide with (motion of the mass member is restricted by) the inner circumferential side restriction surface (122), a shorter falling distance reduces the noise caused by the collision.

According to the embodiment, the torque fluctuation absorbing apparatus includes the annular connection member (3,103a,103c,103e,103g) connecting the mentioned plural mass members (2) in a manner that the mass members (2) retain a predetermined distance from one another.

According to the construction of the embodiment, even when the mass member (2) moves from the first rolling guide surface (121a) to the adjacent first rolling guide surface (121a) via the second rolling guide surface (121b,121d), because the distance between the mass members is retained by the connection member (3,103a,103c,103e,103g), collisions of the adjacent mass members (2) can be prevented. Thus, the generation of the noise by the collision of the adjacent mass members can be restrained. Further, by connecting the plural mass members (2) by means of the annular connection member (3,103a,103c,103e,103g), the plural mass members (2) arranged in a circumferential direction can be integrally connected by the single connection member (3,103a,103c,103e,103g), which restrains an increase in the number of parts compared to a construction in which separate connection members are provided between two adjacent mass members, respectively. Further, because the adjacent mass members (2) are connected in a manner that a small distance is retained, or maintained therebetween, a distance between the adjacent mass members (2) can be reduced compared to a construction without the connection member (3,103a,103c,103e,103g). Thus, the greater number of mass members can be arranged, and absorbing effects of the torsional vibration can be enhanced.

According to the construction of the embodiment, each of the mentioned plural mass members (2) includes the first engagement portion (221,221a) formed with one of a protrusion portion and a hole portion, and the connection member (3,103a,103c,103e,103g) includes the plural second engagement portions (31,131) each of which is formed with the other of the protrusion portion and the hole portion and to each of which the first engagement portion (221,221a) of the mentioned plural mass members (2) engages to be movable in a radial direction of the plate member (1,101a,101b,101c).

According to the construction of the embodiment, by a simple construction of the first engagement portion formed with the protrusion portion (221,221a) (hole portion (31,131)) and the second engagement portion formed with the hole portion (31,131) (protrusion portion (221,221a)), the distance between the mass members can be retained readily while allowing the motion of the mass member (2) in the radial direction of the plate member (1,101a,101b,101c) when the mass member (2) rolls.

According to the construction of the embodiment, one of the connection member (3,103a,103c,103e,103g) and the plate member (1,101a,101b,101c) is formed with the tapered portion (103b,103d,123a,123c) or the protrusion portion (103f,123e) at a portion where the connection member (3,103a,103c,103e,103g) and the plate member (1,101a,101b,101c) face each other.

According to the construction of the embodiment, because a contact dimension of the connection member (3,103a,103c,103e,103g) and the plate member (1,101a,101b,101c) and a contacting radius of the contact portion can be reduced, hysteresis loss due to sliding resistance between the connection member (3,103a,103c,103e,103g) and the plate member (1,101a,101b,101c) can be reduced.

According to the construction of the embodiment, the second rolling guide surface (121b,121d) is formed in a flat surface.

According to the construction of the embodiment, because a moving amount of the mass member (2) when moving inwardly in a radial direction against the centrifugal force when crossing, or passing the second rolling guide surface (121b,121d) can be reduced, compared to a construction in which a second rolling guide surface protrudes inwardly in a radial direction of the plate member (1,101a,101b,101c), the mass member (2) is more readily moved to the adjacent first rolling guide surface (121a) via the second rolling guide surface (121b,121d).

According to the construction of the embodiment, the second rolling guide surface (215b,215c,215d,215e,215f,315a) is configured to allow the mass member (202,302k) to roll thereon with a smaller turning radius compared to on the arc shaped first rolling guide surface (215a,315b).

According to the construction of the embodiment, when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, because the rolling loci of the mass member (202,302k) can be seamlessly switched from the locus in which the mass member (202,302k) rolls on the first rolling guide surface (215a,315b) to the locus in which the mass member (202,302k) rolls on the second rolling guide surface (215b,215c,215d,215e,215f,315a) with smaller turning radius compared to on the first rolling guide surface (215a,315b), the mass member (202,302k) can be rolled with smaller turning radius when moving radially inward of the plate member (201,301a,301d,301g,301j). Accordingly, an increase in the moving range of the mass member (202,302k) can be effectively restrained in a radial direction of the plate member (201,301a,301d,301g,301j).

According to the construction of the embodiment, the mass member (202,302k) includes an outer periphery rolling portion (202e,202d,302m) rolling on the first rolling guide surface (215a,315b) of the plate member (201,301a,301d,301g,301j) and a rolling shaft portion (202c) having a smaller outer diameter than the outer periphery rolling portion (202e,202d,302m) of the mass member (202,302k) and rolling on the second rolling guide surface (215b,215c,215d,215e,215f,315a).

According to the construction of the embodiment, when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, because the rolling loci of the mass member (202,302k) are switched from the locus in which the outer periphery rolling portion (202e,202d,302m) rolls on the first rolling guide surface (215a,315b) to the locus in which the rolling shaft portion (202c) having smaller outer diameter than the outer periphery rolling portion (202e,202d,302m) rolls on the second rolling guide surface (215b,215c,215d,215e,215f,315a) on which the rolling shaft portion (202c) rolls with smaller turning radius than on the first rolling guide surface (215a,315b), the mass member (202,302k) can roll with smaller turning radius readily when the mass member (202,302k) moves radially inward of the plate member (201,301a,301d,301g,301j).

According to the construction of the embodiment, the mass member (202) includes at least one of the first mass member (202a) and the second mass member (202b). The second rolling guide surface (215b,215c,215d,215e,215f) is formed with an inner surface of a rolling guide hole (214,214a,214b,214c,214d) provided penetrating through the plate member (201). The mentioned at least one of the first mass member (202a) and the second mass member (202b) is connected to the rolling shaft portion (202c) positioned in the rolling guide hole (214,214a,214b,214c,214d) in a state where one of the first mass member (202a) and the second mass member (202b) of the mentioned at least one of the first mass member (202a) and the second mass member (202b) is positioned at one of a first side and a second side of the plate member (201) or in a state where the first mass member (202a) and the second mass member (202b) are positioned at either one of the first side and the second side of the plate member (201), respectively.

According to the construction of the embodiment, when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, the rolling shaft portion (202c) of the mass member (202) is allowed to roll along the second rolling guide surface (215b,215c,215d,215e,215f) constructed with the inner surface of the rolling guide hole (214,214a,214b,214c,214d) of the plate member (201) readily.

According to the construction of the embodiment, the plate member (201) includes the recessed portion (212,213) provided at at least one of the first surface (201a) and the second surface (201b) of the plate member (201) and including the first rolling guide surface (215a). The mentioned at least one of the first mass member (202a) and the second mass member (202b) includes the outer periphery rolling portion (202d,202e), the outer periphery rolling portion (202d,202e) of the mentioned at least one of the first mass member (202a) and the second mass member (202b) rolls along the first rolling guide surface (215a) in a state being positioned at the recessed portion (212,213). The rolling shaft portion (202c) rolls along an inner surface of the rolling guide hole (214,214a,214b,214c,214d) forming the second rolling guide surface (215b,215c,215d,215e,215f) when the torsional vibration of the power transmission system (120a) is assumed to be equal to or greater than the predetermined level.

According to the construction of the embodiment, when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level, the rolling loci of the mass member (202) can be seamlessly transited from the locus in which outer periphery rolling portion (202d,202e) of at least one of the first mass member (202a) and the second mass member (202b) rolls on the first rolling guide surface (215a) of the recessed portion of the plate member (201) to the locus in which the rolling shaft portion (202c) rolls on the second rolling guide surface (215b,215c,215d,215e,215f) constructed with the inner surface of the rolling guide hole (214,214a,214b,214c,214d).

According to the construction of the embodiment, the second rolling guide surface (215b,215c,215d,215e,215f) on which the rolling shaft portion (202c) of the mass member (202) rolls is formed in a configuration shorter in a radial direction and longer in a circumferential direction of the plate member (201).

According to the construction of the embodiment, because the second rolling guide surface (215b,215c,215d,215e,215f) can be formed even shorter in a radial direction of the plate member (201), large motion of the mass member (202) in a radially inward of the plate member (201) can be effectively restrained when the torsional vibration of the power transmission system (crankshaft120a) is assumed to be equal to or greater than the predetermined level.

According to the construction of the embodiment, one of the mass member (202) and the plate member (201) is formed with the tapered portion (202h,202i,301b,301c,301e,301f,302e,302f) or the protrusion portion (301h,3011,302i,302j) at a portion where the mass member (202) and the plate member (201) face each other.

According to the construction of the embodiment, because dimensions of an area of contact of the mass member (202) and the plate member (201) can be reduced, hysteresis loss because of the sliding resistance between the mass member (202) and the plate member (201) can be reduced.

According to the construction of the embodiment, the torque fluctuation absorbing apparatus includes the anti-skid member (21a,21b) mounted to cover the outer periphery of the mass member (2,202a,202b,302a,302b,302c,302d,302g,302h).

According to the construction of the embodiment, because the mass member (2,202) is restrained from slipping, or skidding when rolling on the first rolling guide surface (121a,215a) by means of the anti-skid member (21a,21b), the subject torsional vibration with predetermined order can be effectively absorbed.

According to the construction of the embodiment, generation of noise because of collision of the mass member when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level can be restrained.

When the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level, by setting the locus in which the mass member rolls on the second rolling guide surface so as not to largely displace, or move radially inward of the plate member seamlessly, or continuously switching the loci of the mass member from the locus in which the mass member rolls on the arc shaped first rolling guide surface to the locus in which the mass member rolls on the second rolling guide surface which is different from the locus in which the mass member rolls on the first rolling guide surface, deviation, or motion of the mass member in a radially inward direction of the plate member can be restrained after the loci of the mass member are switched from the locus in which the mass member rolls on the first rolling guide surface to the locus in which the mass member rolls on the second rolling guide surface. In those circumstances, because an increase in moving range of the mass member in a radial direction of the plate member can be restrained, the torque fluctuation absorbing apparatus can be downsized by that level, in consequence, generation of noise due to the collisions of the mass member when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level can be restrained while downsizing the torque fluctuation absorbing apparatus.

The torque fluctuation absorbing apparatus for absorbing torsional vibration of the power transmission system in response to torque fluctuation of the engine includes the plate member provided at the power transmission system and including the plural arc shaped rolling guide surfaces formed adjacent to one another in a circumferential direction, and the mass member rolling on the rolling guide surface of the plate member, wherein the plural arc shaped rolling guide surfaces of the plate member are configured to allow the mass member to move to the adjacent rolling guide surface when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level. According to the foregoing construction, because the mass member moves from the rolling guide surface to another rolling guide surface adjacent to the rolling guide surface when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level, the mass member is allowed to move in the circumferential direction of the plate member. In consequence, even when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level, the mass member is restrained from largely moving in a radially inward direction of the plate member. Thus, an increase in the moving range of the mass member in a radial direction of the plate member can be restrained, which allows downsizing the torque fluctuation absorbing apparatus.

According to the torque fluctuation absorbing apparatus, the plate member includes the recessed portion which is provided at the first surface of the plate member and including the plural arc shaped rolling guide surfaces, the mass member includes the outer periphery rolling portion which is configured to roll along the rolling guide surface while being positioned in the recessed portion, and the mass member is configured to move to the adjacent rolling guide surface when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level. According to the foregoing construction, when the torsional vibration of the power transmission system is assumed to be equal to or greater than the predetermined level, the mass member can be moved in a circumferential direction of the plate member readily.

The torque fluctuation absorbing apparatus further includes the annular connection member connecting the plural mass members while retaining a predetermined distance from each other. According to the foregoing construction, even when the mass member moves from the rolling guide surface to another rolling guide surface which is adjacent to the rolling guide surface in a circumferential direction, interval, or distance between the mass members can be retained by the connection member, thus, collisions of the adjacent mass members can be prevented. In consequence, generation of the noise because of the collision of the mass members can be restrained. Further, by connecting plural mass members by means of the annular connection member, the plural mass members arranged in the circumferential direction can be connected integrally with the single connection member, thus, compared to a construction in which separate connection members are provided for the adjacent mass members, respectively to connect between the adjacent mass members, an increase in the number of parts can be restrained. Further, because a state where the adjacent mass members are retained to be spaced with the constant interval, or distance, distance, or interval between the adjacent mass members can be reduced compared to a structure in which the connection member is not provided. Accordingly, because greater number of the mass member can be arranged, the torsional vibration absorbing effects can be enhanced.