Endless belt power transmission systems or components – Pulley with belt-receiving groove formed by drive faces on...
Reexamination Certificate
1999-12-14
2001-11-27
Wright, Dirk (Department: 3682)
Endless belt power transmission systems or components
Pulley with belt-receiving groove formed by drive faces on...
C474S018000
Reexamination Certificate
active
06322466
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a continuously variable chain-belt transmission with cone-disk pulleys (pairs of conical disks) both at the torque-input side and at the torque-output side, an endless flexible torque-transmitting device (often referred to as a chain belt) as well as a device for damping audible noise that occurs as a side effect of transmitting a torque through the chain-belt transmission.
Several different versions within the category of chain-belt transmissions with conical disks are already known. The endless flexible torque-transmitting devices that are used to transmit a torque from the pair of conical disks at the torque-input side to the pair of conical disks at the torque-output side are, for example, link chains or bands of shear-stressed members that run on the conical disks. The link chains employed for this purpose include force-transfer elements with lateral end surfaces that are in frictional contact with the conical disks, thereby transmitting a torque from the pair of conical disks at the input side through the link chain to the pair of conical disks at the output side.
In an arrangement of this kind, the contact between the pairs of conical disks and the force-transfer elements occurs along a polygonal line, because the individual force-transfer elements are spaced apart from each other along the running direction of the chain. As the link chain runs around the pairs of conical disks, the end surfaces of the force transfer elements one after another enter into contact with the conical disks so that the continuous sequence of impacts of the force-transfer elements against the conical disks produces an acoustical resonance in the conical disks.
Given that each of the pairs of conical disks is arranged on a shaft that serves to transmit the torque, the sonic vibrations are propagated through the shafts, their bearings and the transmission housing to the outside and in the end also to the interior of any vehicle equipped with the known state-of-the-art chain-belt transmission.
To attenuate this kind of transmission noise, secondary measures have been employed until now, which included isolating the transmission housing or the chassis tunnel through coated housing components or isolating floor mats.
Another noise-damping measure, known from DE 197 43 675 A1, consists of shell-like elements arranged at the support areas of the conical disks where the space between the shell-like elements and the conical disks is occupied by a pressure fluid, e.g., by the existing oil that is used in the transmission. The concept of this known transmission also provides for a damping layer, e.g., in the form of a polymer layer between the shell-like element and the conical disk. Thus, the aforementioned known transmission represents an attempt to reduce the generation of noise by lessening the impulse transmitted by the link chain as it enters into contact with the conical disks.
OBJECT OF THE INVENTION
Departing from the known state of the art, the object of the present invention is to further develop the chain-belt transmission so that the noise from the impulses transmitted between the link chain and the pairs of conical disks is prevented from reaching the surrounding areas or that the sound propagation through the solid parts is at least significantly reduced.
SUMMARY OF THE INVENTION
To meet this objective, the invention provides a continuously variable chain-belt transmission with cone-disk pulleys (pairs of conical disks) both at the torque-input side and at the torque-output side, an endless flexible torque-transmitting device (often referred to as a chain belt) as well as a device for damping audible noise that occurs as a side effect of transmitting a torque through the chain-belt transmission, where the noise-damping device is arranged in the area of the bearings of at least one of the conical disks. In other words, a noise-damping device is provided in the places where the conical disks are supported in the chain-belt transmission, such as, e.g., an input shaft and/or an output shaft, the housing of the chain-belt transmission or at other contact interfaces between the conical disks and the other parts of the chain-belt transmission.
Arranging the noise-damping device at the bearings provides an acoustical isolation of the conical disks against the parts adjacent to the bearings and thus against all surrounding areas. This concept of active noise elimination prevents the sonic body vibrations caused by the impact of the force-transfer elements on the conical disks from reaching the surrounding area outside of the conical disks or at least significantly reduces the sound propagation through the solid body parts of the structure. According to the invention, the noise-damping device is arranged in the areas of the bearings of axially movable as well as axially fixed conical disks. The noise-damping device in the area of the bearings of the conical disks can be configured as a ring-shaped part of essentially U-shaped cross-section with a seating recess for a damper insert. The term “damper insert” is meant to cover any kind of material or any pair or combination of materials that will in each individual case have the effect of blocking or at least significantly reducing the sound propagation from the conical disks and their bearings to the surrounding structural parts.
According to a more advanced embodiment of the invention, the noise-damping device can be configured as a ring-shaped part of essentially U-shaped cross-section with a seating recess for a damper insert, in which the legs of the U-shaped cross-section have end portions that are angled towards the inside of the U, thus reaching at least partially around the damper insert that is positioned in the seating recess. This arrangement of containing the damper insert in the seating recess of the ring-shaped part provides a particularly high degree of compressive strength so that the rigidity of the conical disks is not affected in a negative way.
It can also be advantageous for the noise-damping device to be configured as a ring-shaped element with an essentially U-shaped cross-section that is open at one axial end and a seating recess for the damper insert. This configuration has the advantage that the damper insert can simply be pushed into the seating recess of the ring-shaped element, which meets the requirement for a simple assembly process.
The aforementioned damper insert can be configured as a single piece of material or it can have a layered structure. In other words, the damper insert can be made of a homogeneous material or as a sandwich structure of several layers which, e.g., could also consist of different materials in order to provide a damper insert capable of damping different input vibration spectra. Possible choices are that the sandwich structure has layers stacked radially from the inner to the outer radius of the ring-shaped element, or that the layers follow each other axially along the lengthwise direction of the ring-shaped element. It is also possible that the sandwich structure is layered both in the radial and axial direction.
According to the invention, the damper insert can be formed, e.g., of an elastomeric material and/or a rubber material and/or a metallic material (e.g., certain alloys) and/or a foam of the aforementioned materials. The choice of a foam for the damper insert has the advantage that it provides an easy installation process for the damper insert, especially in the case where the ring-shaped element has inward-angled legs, by simply injecting a foam of the aforementioned materials into the seating recess.
In accordance with the invention, the damper insert protrudes above the top level of the seating recess by a predetermined height gap so that, with the conical disk seated on the damper insert, there is no direct material contact between the preferably metallic conical disk and the disk bearings that are made of metal alloys.
With a movable conical disk, the arrangement can be such that the ring-shaped element has a damper insert con
Darby & Darby
LuK Getriebe-Systeme GmbH
Wright Dirk
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