Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
2000-06-09
2002-01-08
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S213000
Reexamination Certificate
active
06336867
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 and a damper disk assembly for absorbing or damping torsional vibrations in a power transmission system.
2. Background Information
Clutch disk assemblies used in vehicles have a clutch function for engaging and disengaging the assembly with a flywheel and to receive rotation from the flywheel. Clutch disk assemblies also have a damper function for absorbing and damping torque variations transmitted from the flywheel. These torque variations can also create vibrations.
Generally, vibrations of a vehicle include idling noises (rattle), driving noises (acceleration/deceleration rattle and muffled noises) and tip-in/tip-out (low frequency vibrations). The clutch disk assembly has the above damper function for removing these noises and vibrations.
The idling noises are rattling noises that emanate from a transmission when the transmission is in a neutral position, e.g., while waiting at traffic signals with a disengaged clutch pedal. These noises occur because engine torque is low in an engine idling range and engine combustion causes large torque variations.
The tip-in/tip-outs (low frequency vibrations) are large longitudinal vibrations of a vehicle which occur when a driver rapidly depresses or releases an accelerator. More specifically, excessive vibrations occur when a torque is supplied stepwise to the drive and transmission system. As a result, a torque transmitted to wheels is reversely transmitted from the wheels to the drive system so that an excessive return torque occurs in the wheels. Thereby, the vehicle body transitionally vibrates back-and-forth to a large extent.
Noises during idling are related to a torque region around zero in torsion characteristics of the clutch disk assembly. A lower torsional rigidity can effectively dampen the vibrations. Accordingly, a clutch disk assembly has been provided in which a low rigidity spring is used for achieving nonlinear torsion characteristics having two stages exhibiting low and high rigidities. This clutch disk assembly is configured to exhibit a low torsional rigidity and a low hysteresis torque in the first stages. Therefore, this clutch disk assembly can effectively prevent noises during idling.
As described above, it is necessary to maintain a low rigidity in the first stage and to maintain relatively high rigidities in the second and third stages. For achieving sufficient stop torque, a region of the largest rigidity is required in a region of the largest torsion angle.
A damper mechanism that achieves the aforementioned characteristics is already known. Such a damper mechanism has two kinds of springs that operate in series in the first stage, and two kinds of springs that operate in parallel to provide high rigidity when the torsion angle is large. For example, in a structure disclosed in Japanese Laid-Open Patent Publication No. 5-240302, two kinds of springs operate in series when the torsion angle is small. Further, the two kinds of springs operate in parallel when the torsion angle exceeds a predetermined value.
This damper mechanism includes clutch and retaining plates, a hub, a rotary member, a first elastic member, an intermediate member, and a second elastic member. The clutch and retaining plates are on an input side. The hub is on an output side. The rotary member is arranged between the clutch and retaining plates and the hub. The first elastic member elastically couples the hub and an intermediate member in the rotating direction. The second elastic member elastically couples the intermediate member to the clutch and retaining plates in the rotating direction.
The clutch and retaining plates are provided with compressing portions which are spaced predetermined distances from the circumferentially opposite ends of the first elastic member. Each of stop pins coupling the clutch and retaining plates together is spaced a predetermined distance from an edge of a recess formed in a flange of the hub. Owing to the above structure, when the hub is twisted in one direction with respect to the clutch and retaining plates, the first and second elastic members initially operate in series so that a characteristically low rigidity is achieved. When the torsion angle increases to a predetermined value, the intermediate member engages with the hub, and the compressing portions of the clutch and retaining plates come into contact with the first elastic member. Thereafter, the first elastic member is compressed between the hub and the input plate, and the second elastic member is compressed between the hub and the input plate. Thus, the first and second elastic members operate in parallel between the hub and the input plate. When the torsion angle further increases, the stop pin comes into contact with the edge of the recess in the flange of the hub so that the relative rotation stops.
In the structure described above, the first and second elastic members start to be compressed at the torsion angle of 0 degrees. Therefore, the circumferential space between the stop pin and the edge of the recess in the flange of the hub can excessively increase. More specifically, the recess in the flange must be circumferentially large. In this case, windows that are formed in the flange of the hub for accommodating the elastic members must be small with regards to their circumferential angle or number.
In the structure described above, all the loads of the first and second elastic members act on the hub and the input plate when the first and second elastic members are compressed in parallel. Therefore, the flange of the hub must have an increased strength.
In view of the above, there exists a need for damper mechanism and damper 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
An object of the present invention is to provide a damper mechanism, which can achieve characteristics of a low rigidity in a region of small torsional vibrations as well as characteristics of a high rigidity in a region of a large torsion angle, and which reduces a circumferential space in a relative rotation stop portion.
Another object of the present invention is to provide a damper mechanism, which can achieve a low rigidity in a region of small torsional vibrations as well as a high rigidity in a region of a large torsion angle, and which reduces a necessity for increasing a strength of the flange of the hub.
According to a first aspect of the present invention, a damper mechanism for absorbing and damping torsional vibrations in a rotating direction is provided. The damper mechanism includes a first rotary member, a second rotary member, an intermediate rotary member, a first elastic member, a second elastic member, a first relative rotation stop portion and a compressing portion. The second rotary member is rotatable with respect to the first rotary member. The intermediate rotary member is disposed between the first and second rotary members. The first elastic member is disposed between the first rotary member and the intermediate rotary member. The first elastic member is compressed when relative rotation occurs between the first rotary member and the intermediate rotary member. The second elastic member is disposed between the intermediate rotary member and the second rotary member. The second elastic member is compressed when relative rotation occurs between the intermediate rotary member and the second rotary member. The second elastic member is initially compressed in the rotating direction between the intermediate rotary member and the second rotary member to bear an initial load. The first relative rotation stop portion stops the relative rotation between the first rotary member and the intermediate rotary member when the torsion angle of the first rotary member with r
Binda Greg
Browne Lynne H.
Exedy Corporation
Shinjyu Global IP Counselors, LLP
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