A power transmission device includes a flywheel and a damper device. The flywheel includes a plurality of fixation holes. The damper device includes an input rotary member, an output rotary member, and a pair of first elastic members. The input rotary member and output rotary member each include a plurality of assembling holes disposed in corresponding positions to the plurality of fixation holes of the flywheel. The plurality of assembling holes are arranged in a circumferential direction such that two pairs of the assembling holes, each pair including two adjacent assembling holes, are each disposed at a larger interval than remaining assembling holes to produce a pair of accommodation spaces. A pair of first accommodation portions, accommodating the pair of first elastic members, is disposed radially outside the pair of accommodation spaces.

A damper device includes a first rotor, a second rotor, and an elastic coupling part elastically coupling the first and second rotors in a rotational direction. The elastic coupling part includes first and second elastic members that are each initially disposed in a compressed state in a neutral condition without relative rotation between the first rotor and the second rotor. The first elastic member is transitioned from the compressed state to a free state and then further compressed when torsion of the first rotor with respect to the second rotor is caused from the neutral condition to a first side in the rotational direction. The second elastic member is transitioned from the compressed state to the free state and then further compressed when the torsion of the first rotor with respect to the second rotor is caused from the neutral condition to a second side in the rotational direction.

A damper device includes first and second rotors, and an elastic coupling part elastically coupling the two rotors. The elastic coupling part includes first and second elastic members initially disposed in a compressed state in a neutral condition without relative rotation between the two rotors. The first elastic member is transitioned from the compressed state to a free state and then further compressed when torsion of the first rotor with respect to the second rotor is caused from the neutral condition to a first side. The second elastic member is transitioned from the compressed state to the free state and then further compressed when the torsion of the first rotor with respect to the second rotor is caused from the neutral condition to a second side. Each of the first and second elastic members is transitioned from a one-side contact state to a both-side contact state when actuated in compressed.

A spring seat installed in a damper device including a first rotor, a second rotor and a plurality of elastic members is disclosed. The spring seat includes an end surface support portion and an outer periphery support portion. The end surface support portion includes a recess on a radially middle part thereof. The recess is recessed toward at least one of the elastic members. The end surface support portion supports one end surface of the at least one of the elastic members. The end surface support portion is supported by a pressing surface of a first accommodation portion of the first rotor and a pressing surface of a second accommodation portion of the second rotor. The outer periphery support portion supports part of a radially outer part of the at least one of the elastic members.

A torsion damper disposed inside a coil spring is disclosed. The torsion damper includes a body and a groove. The body is made of resin. Besides, the body has a columnar shape. The groove is provided on the outer peripheral surface of the body.

In a damper device, a dynamic damper is coupled to a first intermediate member, first and second inner-side springs that act in series with each other are straight coil springs disposed between a second intermediate member and a driven member so that outward movement of the springs in a radial direction of the damper device is restricted at respective both ends, and a gap is formed between each body portion of the first and the second inner-side springs and the second intermediate member or a spring abutment portion of the driven member.

In a power transmission device, a dynamic damper is provided in a power transmission path having at least one damper disposed therein, and has an inertial rotating body that can rotate relative to a transmission rotating member forming part of the power transmission path, and a dynamic damper spring that can provide connection between the transmission rotating member and the inertial rotating body. A preset load is applied to the dynamic damper spring in a non-transmitting state of the power transmission path. The dynamic damper spring is supported on either one of the transmission rotating member and the inertial rotating body so as to apply the preset load to the dynamic damper spring in the non-transmitting state, and a gap is set in a rotational direction in the non-transmitting state between the dynamic damper spring and an other one of the transmission rotating member and the inertial rotating body.

A drive assembly for a vehicle drive train includes a base assembly including a base hub configured for non-rotatably connecting to an outer circumferential surface of a transmission input shaft. The base assembly includes a torsional damper fixed to the base hub. The torsional damper includes an input section and an output section drivingly connected by springs. The springs allow relative rotation between the input section and the output section. The output section of the torsional damper is non-rotatably fixed to the base hub. A hub assembly extension is configured for non-rotatably connecting to an engine crankshaft. The hub assembly extension is non-rotatably fixed to the input part of the torsional damper at an engine side of the torsional damper. The torsional damper allows relative rotation between the hub assembly extension and the base hub.

A damper assembly includes a driven plate, an intermediate plate, and elastic drive elements. The intermediate plate includes a radially outer base wall and opposite side walls. The elastic drive elements are interposed, between tabs of the driven plate and tabs of the intermediate plate to permit relative rotational movement therebetween. The elastic drive elements reside in cavities defined, in part, by a substantially annular radially inwardly facing surface of the intermediate plate. A first region of the radially inwardly facing surface in closest proximity to the elastic drive elements has a first radius. A second region of the radially inwardly facing surface axially interposed between the first region and the first side wall has a second radius that is greater than the first radius.

A damper assembly for a clutch, the damper assembly being configured to transfer torque from a driven plate of the clutch to an output shaft of the clutch, a torque transfer plate of the damper assembly including at least one surface coating configured to alter the acoustic properties of the torque transfer plate.