Endless belt power transmission systems or components – Positive drive belt – Belt formed of rigid links
Reexamination Certificate
2000-09-07
2002-11-12
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Positive drive belt
Belt formed of rigid links
C474S215000
Reexamination Certificate
active
06478704
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to improvements in endless flexible torque transmitting devices, and more particularly to improvements in so-called link chains (also known as pintle chains) which can be trained over and can transmit torque between driving and driven rotary parts, for example, over two or more adjustable pulleys or sheaves forming part of an infinitely or continuously variable transmission (CVT) in the power train of a motor vehicle.
A link chain of the above outlined character normally comprises a series of composite links each of which extends transversely of the chain and each of which can comprise a group or array of plate-like components. The components have openings for pintles which extend transversely of the chain and each of which articulately connects two successive links to each other so that the thus coupled links can pivot with respect to one another. Reference may be had, for example, to 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”) and U.S. Pat. No. 4,927,404 (granted May 22, 1990 to Rattunde for “LINK CHAIN FOR AN INFINITELY VARIABLE CONE DRIVE DISK TRANSMISSION”). The disclosure of each and every US and foreign patent and patent application mentioned in the specification of the present application, as well as that of the commonly owned German priority application Serial No. 199 43 010.1 (filed Sep. 9, 1999), is incorporated herein by reference.
A feature of a continuously variable transmission (CVT) is that, at least within a certain range, it can be set to furnish any one of an infinite number of different speed ratios. For example, a CVT can be set to furnish any desired speed ratio between the output element (such as a crankshaft or a camshaft) of a prime mover (such as a combustion engine) of a motor vehicle and the axles of the front and/or rear wheels. This is accomplished by training an endless flexible element (such as a link chain or pintle chain) over a pair of adjustable pulleys each having an axially fixed and an axially adjustable conical flange. The ratio is changed by moving the adjustable flange of one pulley toward the adjacent coaxial axially fixed flange and by simultaneously moving the adjustable flange of the other pulley axially of and away from the respective axially fixed flange. The means for moving the axially movable or shiftable flanges relative to the respective axially fixed flanges often comprises fluid-operated (preferably hydraulic) cylinder and piston assemblies and a control unit which actuates the two assemblies simultaneously, i.e., one of the axially movable flanges moves toward while the other axially movable flange moves away from the associated axially fixed flange, or vice versa. Since the length of the link chain is fixed, the just described simultaneous adjustments of the two axially movable flanges necessarily result in a change of the transmission ratio as well as in uninterrupted transmission of torque in the course of the actual selection of a desired speed ratio.
German patent No. 696 00 141 T2 discloses a link chain wherein each link comprises several components and wherein neighboring links are articulately connected to each other by pintles each of which comprises a pair of elongated rocker elements. This chain has gained acceptance in the relevant industry. However, the patented chain exhibits certain drawbacks such as excessive vibration in actual use. Excessive vibration entails the generation of pronounced noise and adversely affects the reliability and safety of the CVT in actual use. Furthermore, the patented chain is rather bulky which limits its usefulness or necessitates extensive redesigning of parts which embody or cooperate with such transmission.
German patent No. 38 26 809 C1 discloses a modified link chain wherein the links employ components having different thicknesses (as measured transversely of the chain) and/or consisting of different materials. The purpose of such design is to account for the fact that the load upon the links varies as seen transversely of the chain. Thus, the load is normally higher at the marginal portions as well as at the central portion but is less in the regions between the central portion and the two marginal portions. The utilization of links having components of different thicknesses and/or being made of different materials is intended to compensate for the aforementioned variations of load. A drawback of the just described chain is that it also exhibits the tendency to carry out pronounced vibratory movements when in actual use; this adversely affects the smoothness of running as well as the safety of the CVT and results in the generation of excessive noise. In addition, the components of the composite links in the patented chain undergo pronounced deformation and/or exhibit other undesirable defects after a relatively short period of actual use.
German patent No. 198 55 582 A1 discloses a link chain wherein each link comprises several components, and pintles in the form of pairs of rocker elements serving to articulately connect neighboring links to each other. The end portions of the rocker elements of each pair are connected with safety devices in the form of clamps each of which contacts at least one selected rocker element. The purpose of the safety devices is to prevent axial displacements of the rocker elements transversely of the chain, i.e., in the longitudinal directions of the respective pairs of links. The safety devices are designed with a view to ensure reliable retention of the rocker elements against axial shifting, even in the event of stretching of the link chain. It has been ascertained that, though the just described patented link chain holds the rocker elements against axial shifting transversely of the chain, this chain still exhibits several drawbacks such as pronounced vibration in actual use and the afore-discussed undesirable consequences, e.g., the generation of noise, reduced stability and/or others.
OBJECTS OF THE INVENTION
An object of the invention is to provide a novel and improved link chain or pintle chain which is constructed and assembled in such a way that it is sturdier, safer, quieter and not bulkier than heretofore known chains.
Another object of the invention is to provide a simple and inexpensive link chain which can be utilized in existing continuously variable transmissions as a superior substitute for presently known and utilized link chains.
A further object of the present invention is to provide a link chain which comprises simple and inexpensive parts and which can be assembled in a time-saving manner.
An additional object of the instant invention is to provide novel and improved links for use in the above outlined chain.
Still another object of the invention is to provide novel and improved pintles for use in the above outlined link chain.
A further object of the invention is to provide a novel and improved method of making the constituents of and of assembling links for use in a chain of the above outlined character.
Another object of the invention is to provide a continuously variable transmission employing the above outlined link chain as a means for transmitting torque between adjustable pulleys.
An additional object of the invention is to provide a power train which embodies the improved transmission and can be utilized with advantage in motor vehicles and/or for other purposes.
SUMMARY OF THE INVENTION
One feature of the invention resides in the provision of an elongated chain, such as an endless chain which can be utilized with advantage in a continuously variable transmission (CVT), e.g., in the power train of a motor vehicle. The improved chain comprises a series of successive adjacent links each of which extends transversely of the chain whereas the series extends longitudinally (lengthwise) of the chain. Each link includes a group of neighboring substantially plate-like components each having a first side and a second side. The components of each group include outer component
Bucci David A.
Charles Marcus
Darby & Darby
LuK Lamellen und Kupplungsbau Beteiligungs KG
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