192 clutches and power-stop control – Vortex-flow drive and clutch – Including drive-lockup clutch
Reexamination Certificate
1999-12-09
2001-07-31
Marmor, Charles A (Department: 3681)
192 clutches and power-stop control
Vortex-flow drive and clutch
Including drive-lockup clutch
C192S212000
Reexamination Certificate
active
06267213
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a lock-up mechanism of a torque converter. More specifically, the present invention relates to a lock-up damper arranged in a lock-up mechanism for mechanically transmitting torque from a rotatable input body to a rotatable output body of a torque converter.
2. Background Information
In general, the damper mechanism reduces vibrations transmitted from the rotatable input body to the rotatable output body, while transmitting torque from the rotatable input body to the rotatable output body. One example of such a damper mechanism is a damper arranged in a lock-up mechanism of a torque converter (hereinafter referred to as a lock-up damper).
The torque converter is a device that has three types of runners (i.e., an impeller, a turbine and a stator) and normally transmits torque via hydraulic fluid. The impeller is secured to a front cover, which is connected to the rotatable input body. Torque of the impeller is transmitted to the turbine via hydraulic fluid flowing from the impeller to the turbine through the stator. The torque is then transmitted from the turbine to the rotatable output body, which is connected to the turbine.
The lock-up mechanism is typically arranged between the turbine and the front cover. The lock-up mechanism mechanically connects the front cover to the turbine under predetermined conditions in order to transmit torque from the rotatable input body to the rotatable output body.
Such a lock-up mechanism typically includes a piston, a drive plate and a driven plate. The piston is arranged to be urged against the front cover of the torque converter. The drive plate and a driven plate is secured to the piston. The coil springs are supported partially by the drive plate. The driven plate is elastically coupled in a rotational direction to the piston via the coil springs and drive plate. The driven plate is secured to the turbine, which is connected to the rotatable output body. The drive plate, the coil springs and the driven plate further constitute components of a lock-up damper that dampens transmitted vibrations in the lock-up mechanism.
As the lock-up mechanism is activated, the piston is urged against the front cover so that the piston is initially dragged along the front cover. As the piston positively frictionally engages the front cover, torque is transmitted from the front cover to the piston. The torque is then transmitted from the piston to the turbine through the coil springs of the lock-up damper. During this process, the lock-up mechanism not only transmits the torque but also dampens torsional vibrations by providing the lock-up mechanism with coil springs. The torsional vibrations are dampened as the coil springs are repeatedly compressed and expanded between the drive plate and the driven plate. When the coil springs are compressed and expanded, the coil springs slide along the drive plate, which is secured to the piston.
Since there is a strong market demand for downsizing of the torque converter, it is desirable to have a smaller lock-up mechanism. To meet this requirement, in many cases, the drive plate and the driven plate are arranged to oppose each other, and the coil springs are arranged in receiving windows formed in the drive plate and the driven plate. Specifically, the opposite ends of the coil springs engage the opposite circumferential end surfaces of the corresponding receiving window of the drive plate. Also the opposite circumferential end surfaces of the corresponding receiving window of the driven plate engage the opposite ends of the coil springs. Thus, the coil springs elastically couple the drive plate and the driven plate in a circumferential direction.
When the torque converter is rotated, a centrifugal force is applied to the components of the lock-up damper. In addition to the centrifugal force, the drive plate and the driven plate also receive the reaction forces applied from the coil springs in a circumferential direction. The drive plate and driven plate should have enough strength to prevent any damage to them when these centrifugal and circumferential forces are applied to the plates.
As described above, the drive plate and the driven plate should have enough strength to withstand the described forces. It is also desired to reduce the weight of the drive plate and the weight of the driven plate to reduce the weight of the torque converter. However, since these plates have the receiving windows for receiving the coil springs as described before, relatively high stresses are naturally occur around the receiving windows of the drive plate and the driven plate.
In view of the above, there exists a need for a lock-up damper 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
Accordingly, it is an objective of the present invention to provide a lock-up damper that includes a drive plate (input member) and a driven plate (output member) both having reduced weight, while maintaining allowable stress values around their receiving windows (receiving openings).
In accordance with one aspect of the present invention, a lock-up damper is arranged in a lock-up mechanism of a torque converter for mechanically transmitting torque from the rotatable input body to a rotatable output body and includes an input member, an output member and an elastic member. The input member receives torque from the rotatable input body. The output member outputs torque to the rotatable output body. The elastic member is arranged between the input member and the output member. The input member and the output member both include a plurality of receiving openings. These receiving openings are arranged for receiving the elastic member. At least one of the input member and the output member has holes or cutouts positioned radially outward of the receiving openings for the purpose of weight reduction.
In accordance with another aspect of the present invention, a torque converter including a lock-up damper is provided such that when the torque converter is rotated, the centrifugal force is applied to the input member, the output member and the elastic member. As the lock-up mechanism is activated, the input member and the output member rotate or pivot relative to each other. This results in vibrations being transmitted from the rotatable input body to the rotatable output body. The elastic member or coil springs dampens these vibrations. At this point, the reaction force from the elastic member is applied to both the input member and the output member.
Therefore, the centrifugal force that is proportional to the weights of the input member and the output member is applied to both the input member and the output member. The centrifugal force of the elastic member at the respective receiving openings of the input member and the output member that presses radially outwardly on the receiving openings is also applied to both the input member and the output member. Finally, the reaction force from the elastic member is applied to both the input member and the output member. The input member and the output member must have enough strength to withstand these forces. It is especially important to limit the stresses within an allowable range around the receiving openings, where the maximum stress is readily generated by stress concentration.
In accordance with another aspect of the lock-up damper of the present invention, at least one of the input member and the output member has holes or cutouts positioned radially outwardly of the receiving openings for the elastic members. These holes or cutouts are positioned at locations to reduce the weight of the lock-up damper without substantially reducing the strength. With this arrangement, the weight of the lock-up damper is reduced. The presence of holes or cutouts may adversely reduce the rigidity at locations radially outward of the respectiv
Miura Hideki
Nakamura Takeyuki
Yamaguchi Mitsugu
Exedy Corporation
Marmor Charles A
Rodriguez Saul
Shinjyu Global IP Counselors, LLP
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