Rotary shafts – gudgeons – housings – and flexible couplings for ro – Miscellaneous
Reexamination Certificate
1999-08-05
2002-04-02
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Miscellaneous
C029S235000
Reexamination Certificate
active
06364781
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a coupling device having a flywheel mass which faces a drive and is connected to a driver.
2. Discussion of the Prior Art
German reference DE 41 22 135 A1 describes, as can be seen by way of example in FIG. 1, a coupling device in the form of a hydrodynamic torque converter, in which a flywheel mass which faces the drive is formed by a radial flange which runs radially outward from a bearing journal which is mounted in the transmission housing via a holder. The radial flange is firmly connected to the pump shell of the pump wheel. On the other hand, together with an output drive shaft, the turbine wheel forms a flywheel mass on the output-drive side.
Returning to the radially inner bearing journal, this is formed with an internal tooth system which engages in an external tooth system on a drive shaft. This drive shaft likewise has an external tooth system at the other end, via which it engages in a corresponding internal tooth system on the crankshaft of an internal combustion engine. This drive shaft is thus used as a driver for the flywheel mass which faces the drive.
Although the drive shaft produces a connection between the drive and the flywheel mass such that they rotate together, it is impossible, due to play in the tooth systems, to avoid rattling or chattering occurring in the region of these tooth systems when torsional oscillations occur.
A further problem with the known coupling device is that neither the mounting for the bearing journal nor the drive shaft ensure that the flywheel mass which faces the drive is secured axially, and thus that the entire torque converter is secured axially on the crankshaft. The torque converter could thus carry out axial movements which would have to be supported in the transmission and could lead to damage there.
In order to avoid the problems mentioned above, it is normal, as can be seen from FIG. 1 in German reference DE 32 22 119 C1, to which U.S. Pat. No. 4,523,916 corresponds for a plate which is elastic in the axial direction to be screwed detachably to the free end of the crankshaft of a drive. The plate, for its part, is screwed in the radially outer region to the flywheel mass, which faces the drive, of the coupling device, in the present case once again formed by a hydrodynamic torque converter. However, the solution is complex since, in order to screw the flexible plate to the flywheel mass, threaded blocks must be attached to the flywheel mass, at specific distances from one another and distributed around the circumference, these blocks being used to hold the screws. Furthermore, due to the confined physical space conditions and difficult access conditions, it is extremely difficult to screw the flexible plate to the corresponding flywheel mass of the coupling device.
SUMMARY OF THE INVENTION
The invention is based on the object of providing a coupling device that can be attached to a drive, with as little installation complexity as possible, and without any play in the circumferential direction.
As a result of the measure of designing the driver (which is attached to the drive, for example to the crank-shaft of an internal combustion engine) with an axial attachment, in the case of which at least one tooth of a tooth system engages in a corresponding tooth system on a holder which is attached to the flywheel mass, a connection is produced between the holder and the driver, and thus between the drive and the flywheel mass, such that they rotate together. Since at least one of the two tooth systems is subject to radial prestressing with respect to the other tooth system in each case, the connection between the driver and the holder essentially has no radial play. If, for example, the at least one tooth which is formed on the axial attachment of the driver is radially prestressed, this tooth is pressed radially as deeply as possible into the tooth system of the holder in order to allow a force-fitting joint to be produced with the tooth system of the holder. This operates particularly well if the tooth flanks of both tooth systems are each designed with a wedge surface so that, for example, in each case one tooth of the tooth system of the driver penetrates radially, like a wedge, between in each case two teeth of the tooth system of the holder, and is firmly clamped at a predetermined penetration depth. Connected to one another in such a way, there is no play between the tooth systems of the driver and holder, so that no chattering can occur even in the event of severe torsional oscillations. Furthermore, the firm clamping (described above) of the teeth of the driver in the tooth system of the holder when torque is being transmitted results in the following advantage: the torque results in a circumferential force acting on the teeth. Since, however, these teeth engage in one another without any play, each tooth is supported in the circumferential direction, so that the tooth base is not loaded with any bending torque. Instead of this, the tooth just needs to be supported against transverse forces, so that the load remains limited. This advantage is particularly important when the teeth of the tooth system of the driver can be supported on the teeth of a holder which is designed, for example as a ring and, in consequence, has a tooth system which is dimensionally stable in the circumferential direction. The advantage becomes particularly major if the annular holder encloses the driver and is provided with an internal tooth system so that the radial prestressing in the tooth system of the driver is supported during rotation by the centrifugal force, while the ring which encloses the tooth base of the tooth system on the holder radially supports the teeth of the tooth system of the driver.
The tooth system of the driver is assigned an axial securing device which is designed, for example, as a claw with a radial holder, in which case the radial holder engages in a radial depression on the holder. In the situation where this radial holder is designed in the form of a wedge, a clamped connection is once again produced with the matching shape of the radial depression in the holder.
As already described, the tooth system of the driver is radially prestressed with respect to the holder. In order to produce an engaged connection between the driver and the holder when the latter is being pushed onto the driver, an installation apparatus is used, which acts on the driver in such a way that its axial attachment is deformed against the influence of the prestressing such that the engaged connection between the driver and the holder is produced essentially without any axial forces. As soon as this connection has been produced, the influence of the installation apparatus is canceled. This can either be done by removing the installation apparatus completely from the driver or else, in the situation where the installation apparatus is left on the driver, it is released, so that it can no longer exert any influence on the tooth system of the driver.
The measure of using the axial attachment of the driver at an axially free end as a bearing surface for the installation apparatus means that, due to the lever effect of this free end with respect to its other end, which is attached to the radial flange of the driver, a relatively small installation force need be applied by the installation apparatus in the radial direction, in which case this installation force may be less than the prestressing force acting in the direction toward the tooth system of the holder. If the ratio of the installation force to the prestressing force is advantageous in a manner such as this, the prestressing force may be chosen to be sufficiently high so that axial movement between the driver and the holder can be constrained just by the friction force within the tooth system. It is thus possible to dispense with an additional axial securing device.
If an axial securing device is attached to the free end of the axial attachment for the connection between the driver and the holder, this axia
Binda Greg
Mannesmann Sachs AG
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