Torque fluctuation inhibiting device

A torque fluctuation inhibiting device is disclosed. The device includes a mass body, centrifugal elements, guide members, and cam mechanisms. The mass body is rotatable in accordance with and relative to the rotor. The centrifugal elements are radially movable, and disposed to receive a centrifugal force by the rotor and the mass body. The guide members are provided on circumferential ends of each centrifugal element, and guide movement of each centrifugal element while supported by one of the rotor and the mass body. The cam mechanisms convert the centrifugal force into a circumferential force when a relative displacement occurs between the rotor and the mass body while the centrifugal force acts on each centrifugal element. The cam mechanisms each include a cam provided on the other of the rotor and the mass body, and a cam follower disposed on a straight line connecting the guide members in each centrifugal element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2018-114167, filed Jun. 15, 2018. The contents of that application are incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to a torque fluctuation inhibiting device, particularly to a torque fluctuation inhibiting device for inhibiting torque fluctuations in a rotor, to which a torque is inputted, and that is rotated about a rotational axis.

BACKGROUND ART

For example, a clutch device, including a damper device, and a torque converter are provided between an engine and a transmission in an automobile. For reduction in fuel consumption, the torque converter is provided with a lock-up device for mechanically transmitting a torque at a predetermined rotational speed or greater.

Japan Laid-open Patent Application Publication No. 2018-013153 describes a lock-up device including a torque fluctuation inhibiting device. The torque fluctuation inhibiting device described in Japan Laid-open Patent Application Publication No. 2018-013153 includes an inertia ring, a plurality of centrifugal elements and a plurality of cam mechanisms. The inertia ring is rotatable relative to a hub flange to which a torque is transmitted, and a centrifugal force acts on each centrifugal element in rotation of the hub flange and the inertia ring. Each cam mechanism includes a cam provided on the surface of each centrifugal element and a cam follower making contact with the cam.

In the device described in Japan Laid-open Patent Application Publication No. 2018-013153, when the hub flange and the inertia ring are displaced in a rotational direction by torque fluctuations, each cam mechanism is actuated in response to the centrifugal force acting on each centrifugal element, and converts the centrifugal force acting on each centrifugal element into a circumferential force directed to reduce the displacement between the hub flange and the inertia ring. Torque fluctuations are inhibited by this circumferential force.

In the aforementioned device described in Japan Laid-open Patent Application Publication No. 2018-013153, as shown inFIG. 9, two right-side guide rollers and two left-side guide rollers, i.e., two pairs of guide rollers are disposed to stably move each centrifugal element in a radial direction.

In the torque fluctuation inhibiting device described in Japan Laid-open Patent Application Publication No. 2018-013153, the hub flange is provided with a plurality of recessed portions in the outer peripheral part thereof. The recessed portions are opened radially outward. The centrifugal elements are accommodated in the recessed portions, respectively, while being radially movable therein. In such a configuration, gaps are produced between the both circumferential lateral parts of each centrifugal element and sidewalls opposed thereto in each recessed portion. The gaps cannot be eliminated due to the structure of the torque fluctuation inhibiting device.

With the aforementioned gaps between each centrifugal element and each recessed portion, each centrifugal element tilts during actuation of the torque fluctuation inhibiting device. In accordance with the tilt of each centrifugal element, the profile of the cam provided on the outer peripheral surface of each centrifugal element is displaced from a designed profile, whereby a desired torsional characteristic (a characteristic indicating a relation between an angle at which the hub flange and the inertia ring are rotated relative to each other and a torque transmitted between the hub flange and the inertia ring) cannot be obtained. Additionally, the timing of tilt of each centrifugal element depends on the frequency of torque fluctuations. This results in a drawback of fluctuations in torsional characteristics.

In view of the above, when two pairs of guide rollers are provided as shown in FIG. 9 of Japan Laid-open Patent Application Publication No. 2018-013153, tilt of each centrifugal element can be inhibited to some extent. However, installation of the two pairs of guide rollers requires an attachment space radially enlarged as much as possible.

BRIEF SUMMARY

It is an object of the present disclosure to inhibit tilt of a cam surface without radially enlarging an attachment space and obtain stable torsional characteristics.

(1) A torque fluctuation inhibiting device according to the present disclosure is a device for inhibiting torque fluctuations in a rotor to which a torque is inputted. The torque fluctuation inhibiting device includes a mass body, a plurality of centrifugal elements, a pair of guide members and a plurality of cam mechanisms. The mass body is disposed to be rotatable in accordance with the rotor and be rotatable relative to the rotor. The plurality of centrifugal elements are radially movable, and each of the plurality of centrifugal elements is disposed to receive a centrifugal force generated by rotation of the rotor and the mass body. The pair of guide members is provided on both circumferential ends of the each of the plurality of centrifugal elements, and guides movement of the each of the plurality of centrifugal elements while being supported by one of the rotor and the mass body. When a relative displacement is produced between the rotor and the mass body in a rotational direction while the centrifugal force is acting on the each of the plurality of centrifugal elements, the plurality of cam mechanisms each convert the centrifugal force into a circumferential force directed to reduce the relative displacement. The plurality of cam mechanisms each include a cam and a cam follower. The cam is provided on the other of the rotor and the mass body. The cam follower is moved along the cam, and is disposed on a straight line connecting the pair of guide members in the each of the plurality of centrifugal elements.

When a torque is inputted to the rotor in this device, the rotor and the mass body are rotated. When the torque inputted to the rotor does not fluctuate, relative displacement is not produced between the rotor and the mass body in the rotational direction. On the other hand, when the torque inputted to the rotor fluctuates, the relative displacement is produced between the mass body and the rotor in the rotational direction (the displacement will be hereinafter expressed as “rotational phase difference” on an as-needed basis) depending on the extent of torque fluctuations, because the mass body is disposed to be rotatable relative to the rotor.

When the rotor and the mass body are herein rotated, a centrifugal force acts on each centrifugal element. Then, when the relative displacement is produced between the rotor and the mass body in the rotational direction, each cam mechanism is actuated and converts the centrifugal force acting on each centrifugal element into a circumferential force. The circumferential force acts to reduce the relative displacement between the rotor and the mass body. Torque fluctuations are inhibited by the herein described actuation of each cam mechanism.

Moreover, the cam is herein provided on either the rotor or the mass body provided as a different member from each centrifugal element. Because of this, even in tilt of each centrifugal element, the cam is unlikely to change in profile, whereby it is possible to obtain relatively stable torsional characteristics. Especially, the cam follower is disposed on the straight line connecting the pair of guide members. Hence, even in tilt of each centrifugal element, ratio of change in, e.g., position of the cam follower with respect to the cam is reduced. Besides, movement of each centrifugal element is guided by the pair of guide members. Hence, a radial attachment space can be made compact.

(2) Preferably, each of the cam follower and the pair of guide members has a circular cross-section. Additionally, a center of the cam follower is located on a straight line connecting centers of the pair of guide members.

In this case, in tilt of each centrifugal element, each centrifugal element is configured to tilt about a fulcrum, i.e., the center of the cam follower. Because of this, even in tilt of each centrifugal element, fluctuation in contact point between the cam follower and the cam can be inhibited.

(3) Preferably, the center of the cam follower is located on a midpoint of the straight line connecting the centers of the pair of guide members.

In this case, even in tilt of each centrifugal element, fluctuation in contact point between the cam follower and the cam can be further inhibited.

(4) Preferably, the mass body has an annular shape. Additionally, the cam is provided on part of the mass body, and is a curved surface recessed radially outward in a circular-arc shape.

In this case, the cam is provided on the mass body. In other words, each centrifugal element provided with the cam follower is supported and guided by the rotor not by the mass body. Because of this, the amount of inertia of each centrifugal element is not added to that of the mass body. Therefore, the amount of inertia of the mass body is stabilized, and torsional characteristics are stabilized as well.

(5) Preferably, the cam follower is disposed to make contact with an outermost peripheral point on the cam while the rotor and the mass body are not being rotated relative to each other. Additionally, a contact point between the cam and the cam follower is constant regardless of a posture of the each of the plurality of centrifugal elements while the rotor and the mass body are not being rotated relative to each other.

Here, even in tilt of each centrifugal element, the contact point between the cam and the cam follower is constant. Because of this, in torsional characteristics, a stable characteristic is obtained when the torsion angle (an angle of relative rotation between the rotor and the mass body) is “0”.

(6) Preferably, the rotor includes a plurality of pairs of support portions protruding to an outer peripheral side. Additionally, the pair of guide members makes contact with circumferentially outer sides of each pair of the plurality of pairs of support portions, and is radially moved along the each pair of the plurality of pairs of support portions.

Here, the pair of guide members makes contact with the circumferentially outer sides of each pair of support portions, respectively. Because of this, in tilt of each centrifugal element, the pair of guide members makes contact with each pair of support portions, whereby each centrifugal element can be prevented from jumping out to the outer peripheral side. Additionally, when the pair of guide members makes contact with each pair of support portions, each centrifugal element does not tilt any more from the contact position. Moreover, each centrifugal element is moved while the pair of guide members interposes each pair of support portions therebetween. Hence, wobble does not occur between each centrifugal element and the rotor during movement of each centrifugal element.

(7) Preferably, the pair of guide members is a pair of guide rollers rotatably supported by the each of the plurality of centrifugal elements. In this case, movement of each centrifugal element is made smooth.

(8) Preferably, the cam follower is a roller rotatably supported by the each of the plurality of centrifugal elements. In this case, actuation of each cam mechanism is made smooth.

(9) Preferably, the each of the plurality of centrifugal elements has a circumferentially extending shape. Additionally, the each of the plurality of centrifugal elements includes an imbalance portion for setting a center of gravity thereof to deviate from a circumferential center thereof to one circumferential side.

In this case, the center of gravity of each centrifugal element deviates from the circumferential center of each centrifugal element. Because of this, each centrifugal element tilts in a predetermined direction whenever a centrifugal force acts on each centrifugal element. Then, each centrifugal element is configured to be radially moved, while keeping the tilt posture. Therefore, torsional characteristics can be inhibited from becoming unstable.

(10) Preferably, the each of the plurality of centrifugal elements includes a first plate and a second plate. The first and second plates are disposed in axial opposition to each other, and each extend circumferentially. Additionally, the pair of guide members each includes a pin fixing the first plate and the second plate, and a guide roller rotatably supported by the pin.

Overall, according to the present disclosure described above, it is possible to inhibit tilt of a cam surface without radially enlarging an attachment space and obtain stable torsional characteristics.

DETAILED DESCRIPTION

FIG. 1shows an example that a torque fluctuation inhibiting device according to a preferred embodiment of the present disclosure is applied to a lock-up device for a torque converter. Except for members related to the torque fluctuation inhibiting device, members composing the lock-up device and so forth are omitted inFIG. 1.FIGS. 2 to 4are views ofFIG. 1taken along different cross sections. It should be noted that the torque converter and the lock-up device are shown only in part inFIGS. 3 and 4. InFIG. 1, “O” indicates a rotational axis of the torque converter. On the other hand, for convenience of explanation, respective members inFIG. 1are schematically shown inFIGS. 5 and 6.

With reference toFIGS. 3 and 4, a torque converter1includes a front cover2, a torque converter body3, a lock-up device4and an output hub5. A torque is inputted to the front cover2from an engine. The torque converter body3includes an impeller7coupled to the front cover2, a turbine8and a stator (not shown in the drawings). The turbine8is coupled to the output hub5, and an input shaft of a transmission (not shown in the drawings) is capable of being spline-coupled to the inner peripheral part of the output hub5.

The lock-up device4includes a clutch part (not shown in the drawings), and is settable to a lock-up on state and a lock-up off state. In the lock-up on state, the torque inputted to the front cover2is transmitted to the output hub5through the lock-up device4without through the torque converter body3. On the other hand, in the lock-up off state, the torque inputted to the front cover2is transmitted to the output hub5through the torque converter body3.

The lock-up device4includes an input-side rotor (not shown in the drawings), a damper part10, a hub flange12(exemplary rotor) and a torque fluctuation inhibiting device14.

The damper part10is disposed between an input-side member and both the output hub5and the hub flange12. The damper part10includes a plurality of torsion springs. The damper part10transmits the torque, transmitted thereto from the input-side member, to an output side, and absorbs and attenuates torque fluctuations.

The hub flange12is coupled to an output side of the damper part10, while being coupled to the output hub5.

The torque fluctuation inhibiting device14will be explained with reference toFIGS. 1 to 4. It should be noted thatFIG. 1shows part of the hub flange12and the torque fluctuation inhibiting device14. As a whole, the part shown inFIG. 1is disposed in each of four positions aligned at equal angular intervals in a circumferential direction.

The torque fluctuation inhibiting device14includes an inertia ring20(exemplary mass body), four centrifugal elements21, four cam mechanisms22, and four pairs of guide rollers231and232(exemplary guide member), each pair of which is provided in each centrifugal element21.

The inertia ring20has an annular shape and includes four openings20ain the outer peripheral part thereof. The inertia ring20has a rotational axis that is the same as the rotational axis O of the hub flange12. The inertia ring20is rotatable in accordance with the hub flange12, and is also rotatable relative to the hub flange12.

The four openings20aare disposed at equal angular intervals in the circumferential direction so as to be set in corresponding positions to the four cam mechanisms22. Each opening20ahas a circumferentially extending shape. Each opening20ais provided with a curved surface20bon a circumferential middle part thereof. The curved surface20bis recessed radially outward in a circular-arc shape. The curved surface20bfunctions as a cam31(to be described) of each cam mechanism22.

It should be noted that a plurality of weights25are fixed to the inertia ring20so as to increase the inertia amount of the inertia ring20.

The hub flange12is a disc-shaped plate member including a hole12ain the middle part thereof. As shown inFIGS. 3 and 4, the hub flange12is disposed along a lateral surface of the inertia ring20. The inner peripheral part of the hub flange12is located on the inner peripheral side of the inertia ring20, while the end of the inner peripheral part thereof is coupled to the output hub5.

The hub flange12is provided with four pairs of guide protrusions121and122on the outer peripheral part thereof such that each pair of guide protrusions121and122is disposed in a corresponding position to each opening20aof the inertia ring20. In other words, the hub flange12includes four pairs of guide protrusions121and122. The guide protrusions121and122are shaped to protrude from the outer peripheral surface of the hub flange12further radially outward, and are set off in the axial direction (seeFIG. 4). In more detail, as shown inFIG. 2, each pair of guide protrusions121and122is disposed in each opening20aof the inertia ring20. A circumferentially outer part of each guide protrusion121,122is bent in part in the axial direction, and is provided as a support portion121a,122awith which each guide roller231,232makes contact.

As shown inFIGS. 1, 3 and 4, the hub flange12includes a plurality of positioning portions12bin the inner peripheral part thereof. The positioning portions12bare formed by cutting and raising part of the inner peripheral part of the hub flange12. An inner peripheral surface20cof the inertia ring20makes contact with the outer peripheral surfaces of the positioning portions12b, whereby the inertia ring20is radially positioned with respect to the hub flange12.

Each centrifugal element21is radially movable within each opening20aof the inertia ring20. Each centrifugal element21includes first and second plates211and212disposed in axial opposition to each other. The first and second plates211and212, each of which has a circumferentially extending shape, interpose the inertia ring20at the both circumferential ends thereof. Each of the first and second plates211and212is provided with a hole (a hole211afor the first plate211and a hole (not shown in the drawings) for the second plate212; example of imbalance portion) in one circumferential end thereof (i.e., only on one side). With the hole211aherein provided, the centrifugal element21shown inFIG. 1has a center of gravity G eccentric to an R1side in the circumferential direction (i.e., right side inFIG. 2).

It should be noted that similarly to the centrifugal element21shown inFIG. 1, another centrifugal element21, opposed to this centrifugal element21through the rotational axis O, also has the center of gravity G eccentric to the R1side in the circumferential direction. On the other hand, another pair of centrifugal elements21, displaced in position from the centrifugal element21shown inFIG. 1by an angle of 90 degrees, each has the center of gravity G eccentric to an R2side in the circumferential direction. Alternatively, all the four centrifugal elements21can have centers of gravity G eccentric to the same side in the circumferential direction.

As shown inFIG. 2, each centrifugal element21is provided with pins26on the both circumferential ends thereof so as to couple the first and second plates211and212to each other. A collar27is disposed on the outer peripheral part of each pin26so as to maintain an axial gap between the first and second plates211and212at a predetermined value. Additionally, each guide roller231,232is provided on the outer peripheral part of the collar27. It should be noted that in the present preferred embodiment, each guide roller231,232is made in the form of a miniature bearing.

The outer peripheral surface of each guide roller231,232is capable of making contact with the circumferentially outer lateral surface (the support portion121a,122a) of each guide protrusion121,122. Because of this, even when each centrifugal element21tilts, the pair of guide rollers231and232makes contact with the support portions121aand122a, respectively, whereby each centrifugal element21can be prevented from jumping out to the outer peripheral side. Additionally, when the guide rollers231and232make contact with the guide protrusions121and122, respectively, each centrifugal element21does not tilt any more from the contact position. Moreover, each centrifugal element21is moved while the pair of guide rollers231and232interposes the guide protrusions121and122therebetween. Hence, wobble does not occur between each centrifugal element21and the hub flange12during movement of each centrifugal element21.

Furthermore, a support pin28is fixed to the circumferentially middle part of each centrifugal element21. A cam follower30is rotatably attached to the outer periphery of the support pin28. The outer peripheral surface of the cam follower30makes contact with the cam31of the inertia ring20. In other words, the cam follower30is movable along the cam31. It should be noted that in the present preferred embodiment, the cam follower30is made in the form of a bearing.

As shown in a schematic diagram ofFIG. 5, the cam follower30and the pair of guide rollers231and232are disposed such that the center (C0) of the cam follower30is located on a straight line L connecting the centers (C1and C2) of the pair of guide rollers231and232. Additionally, the center C0of the cam follower30is located on the midpoint of the straight line L connecting the centers C1and C2of the pair of guide rollers231and232.

With the aforementioned layout, when the hub flange12and the inertia ring20are not being rotated relative to each other, the position of the cam follower30does not change regardless of the tilt conditions of each centrifugal element21as shown inFIG. 6with dashed two-dotted lines. In more detail, when the hub flange12and the inertia ring20are not being rotated relative to each other, the cam follower30makes contact with an outermost peripheral point C3on the cam31. At this time, with the aforementioned layout of the cam follower30and the pair of guide rollers231and232, the contact point C3between the cam follower30and the cam31becomes constant regardless of the posture of each centrifugal element21.

Each cam mechanism22is composed of the cam follower30and the cam31that corresponds to the circular-arc curved surface20bof the inertia ring20. As described above, the cam follower30makes contact with the cam31, and is moved along the cam31when the hub flange12and the inertia ring20are rotated relative to each other within a predetermined angular range.

Although described below in detail, when rotational phase difference is produced between the hub flange12and the inertia ring20by the contact between the roller30and the cam31, a centrifugal force generated in each centrifugal element21is converted into a circumferential force by which the rotational phase difference is reduced.

<Actuation of Cam Mechanism22>

Actuation of each cam mechanism22(inhibition of torque fluctuations) will be explained withFIGS. 5 and 7. In the lock-up on state, a torque transmitted to the front cover2is transmitted to the hub flange12through the damper part10.

When torque fluctuations do not exist in torque transmission, the hub flange12and the inertia ring20are rotated in the condition shown inFIG. 1. In this condition, the cam follower30in each cam mechanism22makes contact with the outermost peripheral position C3(circumferential middle position) on the cam31, and the rotational phase difference between the hub flange12and the inertia ring20is “0”.

As described above, the rotation-directional relative displacement between the hub flange12and the inertia ring20is referred to as “rotational phase difference”. InFIGS. 5 and 7, these terms indicate displacement between the circumferential middle position of the cam31and the center position of the cam follower30.

When torque fluctuations herein exist in torque transmission, rotational phase difference θ is produced between the hub flange12and the inertia ring20as shown inFIG. 7.

As shown inFIG. 7, when the rotational phase difference θ is produced between the hub flange12and the inertia ring20, the inertia ring20is relatively moved to, for instance, the left side (in an R2direction) inFIG. 7. At this time, a centrifugal force acts on each centrifugal element21(i.e., the cam follower30). Hence, a force to be received by the cam31formed on the inertia ring20from the cam follower30has a direction and a magnitude indicated by P0inFIG. 7. A first force component P1and a second force component P2are produced by the force P0. The first force component P1is directed in the circumferential direction, whereas the second force component P2is directed to move the inertia ring20radially outward.

Additionally, the first force component P1acts as a force to move the inertia ring20rightward (in an R1direction) inFIG. 7. In other words, a force directed to reduce the rotational phase difference between the hub flange12and the inertia ring20is supposed to act on the inertia ring20.

Moreover, the inertia ring20is immovable radially outward. Hence, each centrifugal element21, by which the cam follower30is supported, is supposed to be moved radially inward by a reaction force of the second force component P2.

It should be noted that when the rotational phase difference is reversely produced, the inertia ring20is relatively moved to the right side (in the R1direction) inFIG. 7. However, the aforementioned actuation principle is also true of this case.

As described above, when the rotational phase difference is produced between the hub flange12and the inertia ring20by torque fluctuations, the inertia ring20receives a force (first force component P1) directed to reduce the rotational phase difference between the both by the centrifugal force acting on each centrifugal element21and the working of each cam mechanism22. Torque fluctuations are inhibited by this force.

The aforementioned force inhibiting torque fluctuations varies in accordance with the centrifugal force, in other words, the rotational speed of the hub flange12, and also varies in accordance with the rotational phase difference and the shape of each cam31. Therefore, by suitably setting the shape of each cam31, characteristics of the torque fluctuation inhibiting device14can be made optimal in accordance with the specification of the engine and so forth.

For example, each cam31can be made in a shape that makes the first force component P1linearly vary in accordance with the rotational phase difference in a condition where the centrifugal force acting is constant. Alternatively, each cam31can be made in a shape that makes the first force component P1non-linearly vary in accordance with the rotational phase difference.

When a centrifugal force herein acts on each centrifugal element21, a rotational moment of inertia, oriented in a direction depicted with arrow M inFIG. 6, acts on each centrifugal element21. Specifically, as described above, the center of gravity G of each centrifugal element21is eccentric to the R1side in the rotational direction. Therefore, when the centrifugal force acts on each centrifugal element21, the rotational moment of inertia acts on each centrifugal element21in the counterclockwise direction about an axis including the center C0of the cam follower30(an axis arranged in parallel to the rotational axis of the hub flange12) as shown inFIG. 6. When the rotational moment of inertia (M) acts on each centrifugal element21, each centrifugal element21is changed in posture, and the pair of guide rollers231and232make contact with the circumferentially outer lateral surfaces of the protrusions121and122of the hub flange12, respectively.

As described above, when the rotational moment of inertia (M) acts on each centrifugal element21, the gaps between the guide rollers231and232of each first centrifugal element21and the protrusions121and122become “0”. Then, each centrifugal element21is supposed to be radially moved while keeping the posture described above. Consequently, each centrifugal element21is stabilized in posture during actuation of each cam mechanism22.

It should be noted that as described above, one pair of centrifugal elements21, opposed through the rotational axis, have centers of gravity eccentric to the same direction, whereas the other pair of centrifugal elements21have centers of gravity eccentric reversely to those of one pair of centrifugal elements21. Hence, similar torsional characteristics are obtained on the positive-side torsion angle and the negative-side torsion angle. On the other hand, when all the four centrifugal elements21are set to have centrifugal elements eccentric to the same direction, different torsional characteristics can be obtained.

FIG. 8is a chart showing exemplary torque fluctuation inhibiting characteristics. The horizontal axis indicates rotational speed, whereas the vertical axis indicates torque fluctuations (rotation velocity fluctuations). Characteristic Q1indicates a condition without installation of a device for inhibiting torque fluctuations; characteristic Q2indicates a condition with installation of a well-known dynamic damper device without any cam mechanism; and characteristic Q3indicates a condition with installation of the torque fluctuation inhibiting device14of the present preferred embodiment.

As is obvious fromFIG. 8, in an apparatus in which the well-known dynamic damper device without any cam mechanism is installed (characteristic Q2), torque fluctuations can be inhibited only in a specific rotational speed range. By contrast, in the condition with installation of the cam mechanisms22of the present preferred embodiment (characteristic Q3), torque fluctuations can be inhibited through the entire rotational speed ranges.

Other Preferred Embodiments

The present disclosure is not limited to the preferred embodiment described above, and a variety of changes or modifications can be made without departing from the scope of the present disclosure.

(a) In the aforementioned preferred embodiment, the cams are provided on the inertia ring, whereas the centrifugal elements are supported by the hub flange. Alternatively, the cams can be provided on the hub flange, whereas the centrifugal elements can be supported by the inertia ring.

(b) In the aforementioned preferred embodiment, the center C0of the cam follower30is set to be located on the straight line L connecting the centers C1and C2of the pair of guide rollers231and232. However, the layouts of the respective members are not limited to the above. As long as the center C0of the cam follower30is set to be located approximately on the straight line L, it is possible to obtain advantageous effects similar to those achieved as described above.

Furthermore, as long as the center C0of the cam follower30is set to be located approximately on the midpoint of the straight line L connecting the centers C1and C2of the pair of guide rollers231and232, it is possible to obtain advantageous effects similar to those achieved as described above.

(c) In the aforementioned preferred embodiment, each cam is made in the shape of a circular arc having a constant curvature. Alternatively, each cam can be made in the shape of a curve having a plurality of curvatures.

(d) In the aforementioned preferred embodiment, the present disclosure is applied to the lock-up device for the torque converter. However, the torque fluctuation inhibiting device of the present disclosure is also applicable to other power transmission devices. In this case, the torque fluctuation inhibiting device can be disposed in a variety of layouts.

Moreover, the torque fluctuation inhibiting device of the present disclosure can be further applied to a heretofore well-known dynamic damper device or a power transmission device provided with a pendulum-type damper device.

REFERENCE SIGNS LIST