Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
1999-09-08
2001-09-04
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S213220
Reexamination Certificate
active
06283865
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a damper disk assembly. More specifically, the present invention relates to a damper disk assembly with a dampening mechanism having multiple stages, at least three stages of torsion characteristics.
2. Background Information
A clutch disk assembly used for a clutch of a car has a clutch function of engaging and/or disengaging a flywheel of an engine to a transmission shaft, and a dampening function of absorbing and dampening torsion vibrations transmitted from the flywheel. The clutch disk assembly basically includes a clutch engagement portion, a pair of input plates, a hub and an elastic portion. The pair of input plates is fixedly coupled to the clutch disk. The hub is disposed on an inner circumferential side of the input plate. The elastic portion elastically couples the hub and the input plates together for movement in a rotary or circular direction. Hereinafter, a dampening mechanism includes a pair of input plates, a hub, and an elastic portion.
When the clutch engagement portion is coupled with the flywheel, a torque is inputted to the clutch disk assembly from the flywheel. The torque is transmitted to the hub via the elastic portion, and then is outputted to the shaft extending from the transmission. When a torque fluctuation is input to the clutch disk assembly from the engine, a relative rotation is caused between the pair of input plates and the hub, and the elastic portion is compressed repeatedly in a rotating direction. In addition, the clutch disk assembly typically includes a friction mechanism. The friction mechanism is disposed between the input plates and the hub, and generates a friction resistance when the input plates rotate relatively with respect to the hub. The friction mechanism includes basically a plurality of washers and urging members.
In some conventional clutch disk assemblies, the torsion characteristics are configured to provide four stages for reducing noises and vibrations. The first stage provides a low rigidity, the second stage provides an intermediate rigidity, and third and fourth stages provide high rigidities. For providing the four stages, four kinds elastic members are disposed such that these are successively compressed in accordance with increase in a torsion angle. More specifically, the elastic members for the second, third and fourth stages are disposed in windows formed in a flange of a hub, and are configured to operate in parallel with each other between paired plates.
The friction mechanism is formed of, e.g., a first friction mechanism generating a low hysteresis torque in the first stage and a second friction mechanism which does not operate in the first stage, and generates a high hysteresis torque in the second, third and fourth stages.
According to the above structure, a magnitude of the hysteresis torque rapidly changes in addition to change in rigidity, for example, when the second stage starts (i.e., at a boundary between the first and second stages).
Minute vibrations during idling primarily act in the positive and negative first stages, and are absorbed by characteristics of a low rigidity and a low hysteresis torque. However, the vibrations which operate in the range of the positive and negative first stages may expand to the positive and negative second stages, and the vibrations may be rebounded at the positive and negative stage ends by walls of high hysteresis torques, e.g., in the second stages so that further disadvantageous vibrations (jumping phenomenon) may occur.
In view of the above, there exists a need for a dampening mechanism which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
SUMMARY OF THE INVENTION
An object of the invention is to provide a damper disk assembly with a dampening mechanism providing multiple stages in torsion characteristics, and particularly a mechanism in which rapid rising of a hysteresis torque is suppressed, and thereby noises and vibrations are suppressed.
A damper disk assembly according to the present invention includes a first rotary member, a second rotary member, and a dampening mechanism. The second rotary member is disposed relatively rotatably with respect to the first rotary member. The dampening mechanism is disposed between the first and second rotary members for transmitting a torque therebetween, and dampening torsional vibrations. The dampening mechanism includes a first elastic member, a second elastic member, a third elastic member, and a friction mechanism. The first elastic member is adapted to be compressed in a first stage of torsion characteristics. The second elastic member is adapted to be compressed only in a second stage of the torsion characteristics for providing a higher rigidity than that in the first stage. The third elastic member is disposed so as to operate in series with respect to the second elastic member. The friction mechanism is disposed so as to operate in parallel with respect to the third elastic member. A torque generated by the second elastic member is adapted to exceed a sum of an initial torque of the third elastic member and a hysteresis torque of the friction mechanism.
In the damper disk assembly of the present invention, mentioned above, when a torque is inputted to the first rotary member, for instance, the torque is transmitted to the second rotary member via the dampening mechanism. When the first and second rotary members rotate relatively to one another due to torsional vibrations, the first, second, and third elastic members in the dampening mechanism are compressed in a rotating direction, and a slip occurs in the friction mechanism. While the torsional angle is within the first stage of torsional characteristics, the first elastic member is compressed. While the torsional angle is within the second stage of torsional characteristics, the second elastic member is compressed, providing a higher rigidity than in the first stage. As the second elastic member is compressed in the second stage, the torque generated by the second elastic member exceeds a sum of an initial torque of the third elastic member and a hysteresis torque of the friction mechanism, whereby the third elastic member operates in series in the rotating direction with respect to the second elastic member, and a slip occurs in the friction mechanism. In other words, a slip occurs in the friction mechanism while the torsional angle is within the second stage, generating a higher hysteresis torque. Therefore, a hysteresis torque does not increase suddenly, allowing an efficient absorption of vibrations.
In accordance with another aspect of the present invention, the dampening mechanism of the damper disk assembly as discussed above, further comprising an intermediate member. The intermediate member is disposed so as to transmit a torque between the second and third elastic members. The first and second elastic members are disposed so as to transmit the torque between the first rotary member and the intermediate member. The third elastic member is disposed so as to transmit the torque between the intermediate member and the second rotary member. The first rotary member and the intermediate member form a stop mechanism having a predetermined space in a circumferential direction.
In the damper disk assembly of the present invention, mentioned above, once the first elastic member and the intermediate member contact each other, the second elastic member stops being compressed, and only the third elastic member keeps being compressed. The dampening mechanism generates a larger friction than the case where the second elastic member keeps being compressed by the friction mechanism.
In accordance with another aspect of the present invention, the damper disk assembly includes a first rotary member, a second rotary member, and a dampening mechanism. The second rotary member is disposed relatively rotatably with resp
Harada Takashi
Hashimoto Hideki
Ohshitamoto Shigetomo
Browne Lynne H.
Exedy Corporation
Shinjyu Global IP Counselors, LLP
Thompson Kenn
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