Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
2002-04-25
2004-01-13
Browne, Lynne H. (Department: 3679)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S205000, C192S211000, C192S213000
Reexamination Certificate
active
06676525
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a damper mechanism. More specifically, the present invention relates to a damper mechanism for transmitting a torque while absorbing and damping torsional vibrations.
2. Background Information
A damper mechanism used in a clutch disk assembly of a vehicle has, e.g., an input rotary member, an output rotary member, and an elastic coupling mechanism. The input rotary member is releasably coupled to an input flywheel. The output rotary member is coupled to an input shaft of a transmission. The elastic coupling mechanism elastically couples the rotary members in a rotating direction. The input rotary member is formed of a clutch disk and a pair of input plates fixed to the clutch disk. The output rotary member is formed of a hub, which is unrotatably and axially movably coupled to the transmission input shaft. The hub is formed of a cylindrical boss and a radial flange. The cylindrical boss is spline-engaged with the transmission input shaft, and the radial flange is formed around the boss. The elastic coupling mechanism is formed of a plurality of elastic member assemblies. Each elastic member assembly is formed of a single coil spring or a combination of the coil spring and seat members arranged on opposite ends of the coil spring. Each elastic member assembly is arranged in a window aperture formed in the flange, and is supported at its opposite ends in the rotating direction. Each elastic member assembly is supported in various directions by edges of windows formed in the input plate pair.
In the structure described above, when the input plate pair rotates relatively to the hub, the coil springs are compressed in the rotating direction between the input plates and the hub. Thereby, torsional vibrations supplied to the clutch disk assembly are absorbed and damped by the damper mechanism.
In general, noises generated from a drive system due to torsional vibrations can be classified into groups, each including noises during idling, noises during constant-speed driving, noises during acceleration and deceleration, and muffled or confined noises. For absorbing the torsional vibrations, which may cause these noises, it is therefore necessary to determine the appropriate torsion characteristics for the damper mechanism. Therefore, some conventional damper mechanisms have employed two-stage characteristics. A conventional two-stage damper mechanism achieves a low rigidity and a low hysteresis torque in a region of a small torsion angle for absorbing vibrations during idling. In these conventional two-stage characteristics, the region of high torsion angles may be divided into a region exhibiting an intermediate rigidity and a high hysteresis torque for absorbing muffled noises, as well as a region exhibiting a high rigidity and a high hysteresis torque for absorbing vibrations and noises during acceleration.
In an FF (Front-engine and Front-drive) vehicle, a drive system has a high rigidity so that a resonance point remains in a practical operation range even if the torsion rigidity is reduced for the purpose of improving performance relating to suppression of noises and vibrations. Characteristics of engine speed variations are different between the positive or acceleration side and the negative or deceleration side. In a conventional structure, however, no difference is present in the torsion characteristics between the positive and negative sides. Therefore, even if good damping characteristics can be realized on one side, good damping characteristics cannot be realized on the other side. Thus, good damping characteristics cannot be realized on both the sides.
In connection with the vibration damping performance relating to variations in rotation speed of the transmission with respect to the engine rotation speed, the hysteresis torque can suppress resonance on the positive side, but cannot achieve an adequate damping rate in a positive range lower than the resonance point and the whole negative range. Conversely, the low hysteresis torque can achieve adequate damping rates in the positive range lower than the resonance point and the whole negative range, but cause large variations in rotation speed at the positive resonance point. If the torsion characteristics on the positive side are similar to those on the negative side, and particularly if no difference is present in hysteresis torque between the positive and negative sides, it is impossible to provide torsional damping characteristics that are preferable over the whole operating range of the damper mechanism.
A structure in which the number of elastic members operating on the positive side is larger than the number of elastic members operating on the negative side is known. This structure can thereby provide a rigidity on the positive side that is different from a rigidity on the negative side. Additionally, a structure in which friction generated on the positive side by a friction generating mechanism is different in magnitude from that on the negative side is known as well. However, the friction generating mechanism requires a plurality of friction washers and conical springs, and thus requires a complicated structure formed of a large number of parts.
In view of the above, there exists a need for damper mechanism that 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 mechanism with a simplified structure that can achieve the preferable vibration damping characteristics by providing different torsion characteristics on the positive and negative sides.
According to a first aspect of the present invention, a damper mechanism includes a first rotary member, a second rotary member, a first elastic member, a second elastic member, and a friction generating mechanism. The second rotary member is rotatable with respect to the first rotary member. The first elastic member couples the first and second rotary members together in a rotating direction. The first elastic member is compressed in the rotating direction when relative rotation occurs between the first and second rotary members, and is compressed on positive and negative sides of torsion characteristics. The second elastic member couples the first and second rotary members together in the rotating direction. The second elastic member is compressed in the rotating direction when relative rotation occurs between the first and second rotary members, and is arranged to operate in parallel in the rotating direction with respect to the first elastic member. The second elastic member is compressed on the positive side of the torsion characteristics, and is compressed on the negative side of the torsion characteristics only in a range exceeding a predetermined torsion angle. The friction generating mechanism generates a friction resistance only when the second elastic member is compressed in the rotating direction.
According to the damper mechanism described above, when the first and second rotary members rotate relatively to each other, the first and second elastic members are compressed therebetween to provide predetermined torsion characteristics. On the positive side of the torsion characteristics, the first and second elastic members are compressed to provide a predetermined rigidity. Further, the friction generating mechanism generates friction in accordance with compression of the second elastic member. On the negative side of the torsion characteristics, only the first elastic member is compressed before the torsion angle exceeds a predetermined value. Thus, the second elastic member is not compressed, and the friction generating mechanism does not generate friction. Owing to the above operations, such characteristics can be achieved on the negative side that rigidity is low, and friction is not generated by the friction generating mechanism.
In sum
Exedy Corporation
Shinjyu Global IP Counselors, LLP
Thompson Kenn
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