Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
1999-12-09
2001-09-04
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S213120
Reexamination Certificate
active
06283866
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a dampening disk assembly. More specifically, the present invention relates to a dampening disk assembly having circumferential gaps for preventing a predetermined friction mechanism from operating when small vibrations occur in a greater torsion angular range of the torsion characteristics.
2. Background Information
A clutch disk assembly or dampening disk assembly is often used in a clutch of a vehicle. The clutch or dampening disk assembly has a clutch function for coupling and/or uncoupling a flywheel of the engine to the transmission shaft, and a dampening function for absorbing and dampening torsion vibrations transmitted from the flywheel. Generally, vibrations of a vehicle include rattling during idling, rattling during driving (due to acceleration and deceleration), and tip-in/tip-out (low frequency vibrations). The dampening function of a clutch or dampening disk assembly eliminates these rattling and vibrations.
Rattling during idling is a rattling noise from the transmission that occurs while the vehicle is for instance waiting for the signal, the gear is in neutral and the clutch pedal is let free. The rattling occurs because engine torque is small during idling, and combustion of the engine generates a relatively large torque. As a result, an input gear of the transmission and a counter gear collide into each other, and generate rattling noises.
Tip-in/tip-out rattling (low frequency vibrations) is a back and forth movement of a vehicle that occurs when the driver pushes or let go of the acceleration pedal suddenly. Tip-in/tip-out rattling occurs when the rigidity of the drive transmission is low. A torque transmitted to tires is transmitted back from the tires, and then the torque is retransmitted to the tires. As a result, the vehicle temporarily moves back and forth.
Rattling during idling also occurs when a torque transmitted in the clutch disk assembly is almost zero. To prevent this type of rattling during idling, the torsion rigidity of the clutch disk assembly should be low for such torque. On the other hand, the clutch disk assembly should have a higher rigidity to prevent tip-in/tip-out rattling.
In view of the aforementioned problems, there has been known a clutch or dampening disk assembly, which utilizes two kinds of springs to obtain two levels of torsion characteristics. In the lower torsion angular range, the clutch or dampening disk assembly has low torsion rigidity and low hysteresis torque, such that rattling during idling can be prevented. In the higher torsion angular range, the clutch or dampening disk assembly has high torsion rigidity and high hysteresis torque, such that front and back movements during tip-in/tip-out rattlings are sufficiently dampened.
There has also been known a dampening mechanism in which a friction mechanism is prevented from operating when small vibrations from fluctuations in engine combustion are transmitted in a higher torsion angular range, even though the friction mechanism is adapted to function in the higher torsion angular range. In this manner, the clutch disk assembly dampens small vibrations by generating small hysteresis torque.
In a conventional clutch disk assembly, a resin-made friction member is coupled to, for instance, a retaining plate, such that the friction member and the retaining plate are rotatable to each other within a predetermined angular range. Therefore, when small vibrations occur in the higher torsion angular range of the torsion characteristics, a cone spring slides against the retaining plate. Since the cone spring and the retaining plate are both made of metals, hysteresis torque generated in this case is not adjustable. As a result, hysteresis torque of certain types of vehicles is not adjusted to an adequate level for small vibrations.
In view of the above, there exists a need for a clutch or dampening disk assembly 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
It is an object of the present invention to provide a clutch or dampening disk assembly which allows an easy adjustment of the level of hysteresis torque generated during small vibrations.
In accordance with one aspect of the present invention, the dampening disk assembly comprises first and second input disk plate members, a hub, an intermediate disk plate member, a friction member, an urging member, intermediate mechanisms, a first elastic member and a second elastic member. The first and second input disk plate members are fixed to each other and are disposed in an axial direction with a gap there between. The hub is disposed on an inner circumferential side of the first and second input disk plate members. The intermediate disk plate member is disposed on an outer circumferential side of the hub and between the first and second input disk plate members in the axial direction. The friction member is disposed between the second input disk plate member and the intermediate disk plate member, and the friction member engages with the second input disk plate member, movably in the axial direction, so that torque may be input from the second input disk plate member. The urging member is disposed between the friction member and the second input disk plate member in the axial direction, and the urging member gives the friction member and the second input disk plate member resiliency in the axial direction. The first elastic member elastically couples the intermediate mechanisms with the hub in the rotational direction. The first elastic member is a member, which brings about low rigidity within a lower torsion angular range of torsion characteristics. The second elastic member elastically couples the first and second input disk plate members with the intermediate disk plate member in the rotational direction. The second elastic member is a member, which brings about high rigidity within a higher torsion angular range of torsion characteristics.
The intermediate mechanisms comprise a first intermediate member and a second intermediate member. The first intermediate member is disposed so as to contact the friction member from the axial direction. The second intermediate member is disposed between the first intermediate member and the intermediate disk plate member in the axial direction so as to transmit torque between the first intermediate member and the intermediate disk plate member. A predetermined gap, which prevents the friction member and the intermediate mechanisms from sliding against small torsion vibration within the higher torsion angular range, is provided with at least one of between the first intermediate member and the second intermediate member in the rotational direction and between the second intermediate member and the intermediate disk plate member in the rotational direction.
According to the dampening disk assembly as set forth above, when torque is input to the first and second input disk plate members, the torque is transmitted from the input disk plate members to the second elastic member, the intermediate disk plate member, the intermediate mechanisms, the first elastic member, and the hub in that order. Also, when torsion vibration is generated in the dampening disk assembly, the first and second input disk plate members rotate relatively to each other and the first and the second elastic members are compressed in the rotational direction between the input disk plate members. In this manner, various torsion vibrations is effectively absorbed and dampened.
The torsion characteristic of the dampening disk assembly will be explained using operation in which the hub is rotated in one direction relative to the first and second input disk plate members, which are fixed to other members. Within the lower torsion angular range, the first elastic member is compressed in the rotational direction and a low rigidity characteristic i
Fujioka Keisuke
Harada Takashi
Hashimoto Hideki
Binda Greg
Browne Lynne H.
Exedy Corporation
Shinjyu Global IP Counselors, LLP
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