Machine element or mechanism – Elements – Flywheel – motion smoothing-type
Reexamination Certificate
1999-02-09
2002-02-05
Luong, Vinh T. (Department: 3682)
Machine element or mechanism
Elements
Flywheel, motion smoothing-type
C074S574300, C475S347000, C464S068800
Reexamination Certificate
active
06343527
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a coupling device with a centrifugal mass facing a drive train.
2. Discussion of the Prior Art
German reference DE 41 22 135 A1 describes (e.g., in
FIG. 1
) a coupling device in the form of a hydrodynamic torque converter, in which a centrifugal mass that faces the drive train consists of a radial flange. The radial flange runs radially outward from a bearing journal mounted via a holding means in the gear housing and is securely connected to the pump shell of the pump wheel. On the other hand, the turbine wheel forms, with an output shaft, an output-side centrifugal mass.
The radially inner bearing journal is embodied with an internal tooth system, which engages into an external tooth system on a drive shaft. The drive shaft also has an external tooth system at its other end, via which it engages into a corresponding internal tooth system on the crank shaft of an internal combustion engine. The drive shaft thus serves as a driving gear for the centrifugal mass facing the drive train.
Although a rotation-proof connection between the drive train and the centrifugal mass is thus established by the drive shaft, it is unavoidable, due to play in the tooth systems, that when torsional vibrations occur, there is rattling in the area of these tooth systems.
It is also problematic in this known coupling device that neither the holding means for the bearing journal nor the drive shaft ensures the axial attachment of the centrifugal mass that faces the drive train—and thus of the entire torque converter—to the crank shaft. As a result, the torque converter can carry out axial movements, which must be supported in the gearbox and could lead to damage there.
To avoid these problems, a plate that is elastic in the axial direction is usually screwed to the free end of the crank shaft of the drive train, as shown in FIG. 1 of German reference DE 32 22 119 C1. The plate, in the radially outer area, is also screwed to the drive-side centrifugal mass of the coupling device, which, in this case, is again a hydrodynamic torque converter. However, this solution is expensive, because the screw connection of the flexible plate to the centrifugal mass requires that threaded blocks, which serve to hold the screws, be distributed around and attached to the circumference at a certain distance from each other. Moreover, a screw connection of the flexible plate to the centrifugal mass of the coupling device is highly problematic due to cramped space conditions and difficult access.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a coupling device that can be attached to a drive train without play in the circumferential direction, and that has the least possible assembly expense.
Pursuant to this object, and others which will become apparent hereafter, one aspect of the present invention resides in a coupling device which has a driving gear that acts on a drive train and has a centrifugal mass facing the drive train which is in rotation-proof active connection with the driving gear. In accommodating fixture is provided on the centrifugal mass so as to face the driving gear. The accommodating fixture having a first toothed system. The driving gear has an axial shoulder embodied with a second tooth system on a side facing the accommodating fixture so that at least one tooth of the second tooth system engages into a space between two teeth of the first tooth system whereby the teeth of at least one of the two toothed systems are under radial prestress relative to the other toothed system.
Because the driving gear, which is attached to the drive train, e.g., the crank shaft, of an internal combustion engine, has an axial shoulder, on which is embodied at least one tooth of a tooth system that engages into a corresponding tooth system on an accommodating fixture attached to the centrifugal mass, a rotation-proof connection can be established between the accommodating fixture and the driving gear, and thus between the drive train and the centrifugal mass. Since at least one of the two tooth systems is under radial prestress relative to the other tooth system, the connection between the driving gear and the accommodating fixture is substantially without radial play. For example, when there is radial prestress of the tooth or teeth embodied on the axial shoulder of the driving gear, these teeth are pressed as deeply as possible into the tooth system of the accommodating fixture, so that a force-locking connection to the tooth system of the accommodating fixture is established. This works especially well when the tooth faces of both tooth systems are embodied with wedge-like surfaces, so that a tooth of the driving gear tooth system penetrates radially between two teeth of the tooth system of the accommodating fixture, for example, and is clamped at a predetermined penetration depth. When connected to each other in this fashion, the tooth systems of the driving gear and the accommodating fixture have no play between them, so that even during strong torsional vibrations no rattling can occur. In addition, due to the aforementioned clamping of the teeth of the driving gear in the tooth system of the accommodating fixture, an advantage results during the transmission of torque, namely, due to the torque, a circumferential force acts on the teeth. Because the teeth are engaged with each other without play, each tooth is supported in the circumferential direction, so that the tooth base is not loaded with a bending moment. Instead, each tooth needs only to be supported against transverse forces, so that the load remains limited. This advantage is especially important when the teeth of the driving gear tooth system are supportable by the teeth of an accommodating fixture that is embodied as a ring, for example, and thus has a tooth system whose form is stable in the circumferential direction. The advantage is especially great when the ring-shaped accommodating fixture surrounds the driving gear and is equipped with an internal tooth system, so that the radial prestress of the tooth system of the driving gear, upon rotation, is supplemented by centrifugal force, while the ring surrounding the tooth base of the tooth system on the accommodating fixture radially supports the teeth of the tooth system on the driving gear.
According to another embodiment of the invention, the driving gear tooth system has an axial protection means embodied, for example, as a claw with a radial holding device that engages into a radial depression on the accommodating fixture. When the radial holding device is embodied in wedge-like fashion, a clamping connection is again established with the matching radial depression in the accommodating fixture.
As noted above, the driving gear tooth system is radially prestressed relative to the accommodating fixture. To establish an engaged connection between the driving gear and the accommodating fixture when the accommodating fixture is moved onto the driving gear, an assembly mechanism is used. The assembly mechanism acts on the driving gear so that the axial shoulder of the driving gear is deformed against the prestress effect, so that the engaged connection between the driving gear and the accommodating fixture is established substantially without axial force. As soon as this connection is established, the activity of the assembly mechanism is terminated. This can be done either by removing the assembly mechanism completely from the driving gear or, if the assembly mechanism is to remain on the driving gear, by detaching the assembly mechanism so that it can no longer exert any influence on the driving gear tooth system.
Because the axial shoulder on an axially free end of the driving gear serves as the support surface for the assembly mechanism, the assembly mechanism needs to apply only a relatively small assembly force in the radial direction. This is due to the lever effect of the axially free end relative to the other end, which is attached to the radial flange of the driving gear. The asse
Cohen & Pontani, Lieberman & Pavane
Luong Vinh T.
Mannesmann Sachs AG
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