Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on... – Load responsive
Reexamination Certificate
2000-11-08
2002-09-03
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
Load responsive
C474S070000, C464S162000
Reexamination Certificate
active
06443864
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements in mechanisms or systems for transmission of torque between coaxial rotary parts. More particularly, the invention relates to improvements in mechanisms which can be utilized for the transmission of torque between coaxial rotary parts at least one of which is movable or should be free to move axially relative to the other part. Examples of structures in which. the torque transmitting mechanism of the present invention can be put to use are so-called continuously variable transmissions (CVT) wherein one of two adjustable pulleys or sheaves can transmit torque to the other pulley or sheave by way of an endless chain or belt. At least one of the pulleys has an axially fixed first flange which is secured to a driving or driven shaft and a second flange which is movable axially of the shaft toward and away from but should share the angular movements of the first flange.
Continuously variable transmissions are becoming increasingly popular for the transmission of torque in the power trains of motor vehicles, e.g., between a manually or automatically operable clutch and a differential for the front or rear wheels of the vehicle. As a rule, a continuously variable transmission (hereinafter called CVT for short) employs a first shaft which is driven by the prime mover (such as an internal combustion engine) in the power train of a motor vehicle and carries a first adjustable pulley, a second shaft which drives the differential and also carries an adjustable pulley, and an endless belt or chain which is trained over the pulleys. Each pulley has a first flange which is affixed to the respective shaft, and a second flange which is movable axially of the respective shaft toward and away from the associated axially fixed flange. The ratio of the CVT is changed by causing or permitting the axially movable flange of one pulley to move axially of the respective shaft toward the other flange of the one pulley simultaneously with a movement of the movable flange of the other pulley away from the axially fixed flange, or vice versa.
Several embodiments of continuously variable transmissions of the just outlined character are disclosed, for example, in commonly owned U.S. Pat. Nos. 5,295,915 (granted Mar. 22, 1994 to Friedmann for “CONTINUOUSLY VARIABLE SPEED TRANSMISSION”), 5,711,730 (granted Jan. 27, 1998 to Friedmann et al. for “TORQUE MONITORING APPARATUS”) and 5,725,447 (granted Mar. 10, 1998 to Friedmann et al. for “POWER TRAIN WITH INFINITELY VARIABLE RATIO TRANSMISSION”).
In a so-called wet-running CVT, the torque transmitting connection between each shaft and the axially movable flange of the respective pulley comprises rotation preventing means of the type employing teeth, splines and/or spheres. On the other hand, a dry-running CVT often employs one or more leaf springs which can yield to permit axial movements of one flange relative to the other flange but are intended to compel both flanges to rotate in the same direction. However, the angular position of the movable flange relative to the angular position of the other flange (i.e., of the flange which is held against axial movement relative to its shaft) varies while the leaf spring or springs permits or permit the axially movable flange to move axially toward or away from the other flange. Such angular displacement entails additional stressing of the endless flexible element, e.g., a chain of the type disclosed in U.S. Pat. No. 4,927,404 granted May 22, 1990 to Rattunde for “LINK CHAIN FOR AN INFINITELY VARIABLE CONE DRIVE DISK TRANSMISSION” or in U.S. Pat. No. 5,427,583 granted Jun. 27, 1995 to Wolf for “LOW-NOISE, TRIPLE SIDE BAR SPROCKET CHAIN FOR INFINITELY VARIABLE TRANSMISSION”.
The disclosure of the commonly owned copending German priority patent application Serial No. 199 53 580.9 (filed Nov. 8, 1999) and the disclosures of all US and foreign patents and patent applications identified in the specification of the present application are incorporated herein by reference.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a novel and improved torque transmitting mechanism or system which prevents the axially movable part of an adjustable pulley or the like from turning relative to the axially fixed part during axial movement toward and away from the axially fixed part without the need for the establishment of a direct rotation-preventing connection between the two parts.
Another object of the invention is to provide a torque transmitting mechanism which employs leaf springs or analogous components but in such a way that these components cannot compel the axially movable part to turn (even slightly) relative to the axially fixed part during movement of the axially movable part toward or away from the axially fixed part.
A further object of the invention is to provide a torque transmitting mechanism which is compact, simple and inexpensive but highly reliable for long periods of use, e.g., in the power trains of motor vehicles.
An additional object of the invention is to provide a continuously variable transmission which employs one or more torque transmitting mechanisms or systems of the above outlined character.
Still another object of the invention is to provide a novel and improved torque transmitting connection between a rotary shaft and a part (such as a conical flange of a pulley on the shaft) which should be free or compelled to rotate with the shaft but should be prevented from carrying out any, even slight, angular movements relative to the shaft.
A further object of the invention is to provide a novel and improved method of transmitting torque between coaxial parts one of which must be free to move axially of but must be compelled to invariably rotate with the other part.
Another object of the invention is to provide a novel and improved torque transmitting mechanism or system which employs leaf springs.
An additional object of the invention is to simplify but to simultaneously enhance the reliability of a torque transmitting connection between a driving or driven shaft and an axially movable part which shares all angular movements of the shaft.
Still another object of the invention is to provide a torque transmitting mechanism which can be employed in numerous existing types of dry-running continuously variable transmissions.
A further object of the invention is to provide novel and improved springs for use in mechanisms which serve to transmit torque between a first rotary part and a second rotary part that should be free to move axially of but should not turn relative to the first rotary part.
An additional object of the invention is to prevent excessive stressing of chains which are utilized to transmit torque between the pulleys of a continuously variable transmission.
SUMMARY OF THE INVENTION
One feature of the present invention resides in the provision of a mechanism which is designed to transmit torque between first and second members. These members are rotatable about a common axis and at least one thereof is movable relative to the other member in the direction of the common axis. The improved torque transmitting mechanism comprises first and second frames (such as polygonal, oval or circular frames) which spacedly surround the common axis when the mechanism is in use and at least one of which is deformable. The mechanism further comprises a plurality of means (e.g., rivets, threaded fasteners, snap-on fasteners or the like) which serve to secure at least two spaced-apart sections of the first frame for rotation with the first member, a plurality of means (e.g., rivets, threaded fasteners or any other suitable fasteners) for mounting at least two spaced-apart sections of the second frame for rotation with the second member, and a plurality of means (e.g., rivets and/or other suitable fasteners) for non-rotatably coupling the frames to each other at a plurality of locations each of which is disposed between one section of the first frame and one section of the second frame.
The securing means can alternate with the coupli
Bucci David A.
Darby & Darby
LuK Lamellen und Kupplungsbau GmbH
McAnulty Timothy
LandOfFree
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