Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Coil spring
Reexamination Certificate
1999-04-22
2001-10-09
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Coil spring
C192S201000, C192S213210, C192S213110, C464S054000, C464S084000, C464S061100
Reexamination Certificate
active
06299539
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a friction plate damper with a primary plate and a secondary plate, which interact with each other by means of a friction device, and a control device for the friction which is dependent on the speed of rotation.
2. Description of the Prior Art
A friction plate damper of this nature is known, from German Patent DE 196 11 268 A1. With this friction plate damper, a primary section supports a number of lamellar rings, arranged axially behind one another. These rings are capable of being moved, which in each case engage between axially movable lamellar rings connected to the secondary section. As a result the lamellar rings are pressed against each other by leaf springs having centrifugal weights exerting axial pressure, at the outer axial ends. As a result, a pressure force is exerted on the lamellar rings, which decreases as the speed of rotation decreases, with the result that the pressure force and therefore also the friction force reverts to zero once a critical speed of rotation is exceeded.
SUMMARY OF THE INVENTION
The centrifugal weights, however, require a relatively large space, thus, the space available for the damping springs is reduced. The objective of the invention is to provide a friction plate damper with a primary plate and a secondary plate, which interact by means of a friction device. In addition, a control device is provided for the friction, dependent on the speed of rotation, in which sufficient space is provided for damping springs.
As a solution, the invention proposes a friction plate damper of a generic nature, in which the friction device features a contact arrangement, to be imposed essentially radially. In addition, the friction control device comprises a spring element, which takes effect essentially radially on the contact arrangement.
In contrast with the known arrangements, in which the friction is controlled by means of axially imposed contact, this invention allows for the avoidance of a complex mechanism which occupy considerable space, taking effect radially and converting centrifugal forces into axial forces. Rather, the spring element can take effect directly on the contact arrangement, in which situation its pressure forces are defined by centrifugal forces and are dependent on the rotational speed without further measures being required.
To advantage, the contact arrangement is subjected to force by means of the spring element radially from outside, at low rotational speeds of the friction plate damper. At low rotational speeds, this incurs a high friction force and therefore a high degree of damping, which is necessary to avoid the rotational speed acceleration being excessive between the primary and secondary plates, in particular at resonance penetration.
At high rotational speeds, the spring element exerts centrifugal forces, so that the forces exerted on the contact arrangement, and therefore also the friction, are reduced. In this way, at high rotational speeds the damping is reduced in the desired manner. In addition, a relative movement, as far as possible free of friction, is guaranteed between the primary and secondary plates.
A particularly complex embodiment of this arrangement is obtained if the friction device interacts by way of friction with the secondary plate, at least at low rotational speed, and the primary plate is connected by way of a drive. In this context, it is understood that the drive connection between the friction device and the primary plate does not have to be a rigid connection. This can be provided for preference by way of a spring arrangement, e.g. also by means of the damping springs or by means of a coupling element dependant on the rotational speed.
To achieve these objects the invention includes a generic friction plate damper, in which the friction device interacts by way of friction with the secondary plate. The plate is mounted so that is capable of rotational movement in relation to the primary plate at least within a small angle. In addition, the friction control device comprises a coupling element, dependent on the rotational speed, between the primary plate and the friction device.
An arrangement of this nature also guarantees a compact structure for the friction plate damper. With the arrangements according to the prior art the forces required for the friction are created by the friction control device. Instead, in the present invention, the coupling element is rotational speed dependent, and requires only the forces required to carry the friction device in sympathy. For this reason it can be designed to be considerably more compact.
The rotationally-movable mounting of the friction device in relation to the primary plate provides a degree of freedom of the friction device in relation to the primary plate. This occurs when the coupling element, rotational speed dependent, releases the coupling of the primary plate and the friction device.
The rotational speed dependent coupling element preferably encompasses a spring element taking effect radially. In this way, this design can be realized more simply.
The radially effective spring element imposes force radially from the outside onto a contact arrangement of the friction device and/or of the primary plate. Thus, a rotational speed dependent coupling is created, which is released at high rotational speeds. As a result, in a relatively simple manner a high degree of damping at low rotational speeds, and a low degree of damping at high rotational speeds can be guaranteed. This result, as already explained, is desirable for this type of friction plate damper.
To achieve a reliable drive connection between the primary plate and the friction device, the radially effective spring element can be connected, for the purpose of rotational drive, by means of a carrier element of the primary plate or the friction device, with either the primary plate or the friction device.
Therefore, with this invention, it is not relevance whether the primary plate or the secondary plate is the driving element or the driven element of the friction plate damper. In addition to this, this invention can be used for other types of torsion vibration dampers.
A control device for the friction can be created in a simple manner by the friction plate damper featuring media which limit the relative rotation between friction device and secondary plate in at least one direction. In this way, the defined friction between the friction device and the secondary plate occurs only at this point between the friction device and the secondary plate, while rotational movements extending beyond this, between the primary plate and the secondary plate, and therefore also with other friction coefficients, can be encountered.
A simple arrangement to limit the relative position is attained if the limiting media encompass a stop on the friction device and a stop on the secondary plate, which come into mutual contact at a specific angle of rotation.
The radially effective spring element engages by friction with the contact arrangement, which is to be applied essentially radially. This has the advantage that it will lift off the contact device easily at the appropriate rotational speed. With this arrangement in particular, a friction displacement between the spring element and the contact arrangement is possible. Thus, for example, if a relatively high torque is applied, and a relative rotation between the friction device and the secondary plate is restricted, the friction device will be displaced in relation to the primary plate despite the spring element being in contact. This occurs at a relatively high resistance, which meets the requirement for attaining a high damping effect at low rotational speed and high torque values. As soon as the rotational speed exceeds a specific value, the spring element is released and the friction between the friction device and the primary plate drips to a desired low value.
An especially compact arrangement of a friction plate damper is created if the friction device encompasses a frict
Heidingsfeld Dietmar
Rohs Hans
Rohs Ulrich
Browne Lynne H.
Collard & Roe P.C.
Dunwoody Aaron M
Rohs Voigt Patentverwertungs-gesellschaft mbH
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