Self-aligning splined male shaft head and engagement method

Details Self-aligning splined male shaft head and engagement method Self-aligning splined male shaft head and engagement method

2001-03-16

2002-11-19

Binda, Greg (Department: 3679)

Rotary shafts, gudgeons, housings, and flexible couplings for ro

Shafting

With disparate device for coupling shaft to additional shaft...

C464S901000, C403S359400

Reexamination Certificate

active

06482094

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a male shaft head having spline teeth for engagement into a splined female hub or the like.
BACKGROUND INFORMATION
In many mechanical applications in various different technical fields, it is necessary to temporarily or releasably engage two rotatable members with each other. Predominantly this involves engaging a rotatable male shaft head into a rotatable female hub or other receiver opening. Throughout this specification, the term “hub” will be used generally to refer to any opening or recess adapted to receive a male shaft head therein. The engagement of the male shaft head into the female hub is commonly achieved by providing one or more axially longitudinally extending keys or spline teeth on the outer circumference of the shaft head, and corresponding spline grooves or keyways on the inner circumference of the hub. The splined shaft head further has corresponding spline grooves respectively between neighboring spline teeth, and the splined hub has spline teeth respectively between neighboring spline grooves. The spline teeth of the male shaft head slidingly engage with the corresponding spline grooves in the hub, so as to connect the shaft head with the hub in a rotation- or a torque-transmitting manner.
While the above described typical splined interconnection between the shaft head and the hub provides a good positive form-locking connection for torque transmission between the two components, it is generally difficult and problematic to achieve the connection Namely, in order to insert the splined male shaft head into the splined hub, the shaft head and the hub must be precisely aligned with each other in terms of their respective radial positions and in terms of their respective rotational positions. In other words, the center axis of the shaft head must be precisely aligned with the center axis of the hub, and the splined teeth of the shaft head must be precisely rotationally aligned with the corresponding spline grooves of the hub. Otherwise, it will not be possible to insert the shaft head into the hub, due to the blocking contact of the spline teeth of the two components with each other. Moreover, if there is only a slight misalignment between the two parts, in either the rotational or radial directions, the front edges of the spline teeth will suffer wear, which becomes cumulative over the course of repeatedly connecting and disconnecting the shaft head to and from mating splined hubs.
To address some of the above problems, it is also conventionally known to provide a splined shaft head with at least one spline tooth or a spline segment including plural spline teeth, which is spring-loaded and radially deflectable relative to the remaining body of the shaft head. As such a shaft head is inserted into the hub, the spring-loaded tooth or teeth will deflect radially inwardly against the spring-biasing force in order to allow some elastic play or yielding between this tooth or teeth of the shaft head and the hub. Thereby, the spring-loaded teeth are intended to click into place in the proper alignment with the spline grooves of the splined hub due to the biasing force of the spring that urges these teeth radially outwardly. Once the spring-loaded teeth are engaged properly in the spline grooves of the hub, the remaining fixed teeth will also be properly engaged into the corresponding spline grooves of the hub to establish the full torque transmitting engagement of the shaft head to the hub.
The above described spring-loaded shaft head, however, suffers several disadvantages and problems in actual use. Particularly, the spring-loaded tooth or teeth suffer rapid wear, because the spring-loaded arrangement thereof purposely allows for misalignment and play between the spline teeth of the shaft head and the spline grooves of the hub, and then urges the spring-loaded spline teeth into the proper alignment and engagement with the spline grooves of the hub with an elastic spring-load applied thereto. Also, the moveable spring-loaded arrangement of these teeth sometimes leads to jamming of the shaft head with an improper alignment relative to the hub. As a result of the loose or yielding arrangement, and especially further in view of the resulting wear and occasional jamming, the spring-loaded shaft head cannot ensure a high degree of precision and play-free engagement between the shaft head and the hub. As a further disadvantage, such a spring-loaded shaft head suffers high costs and effort with regard to the initial manufacturing and installation thereof, and in relation to ongoing maintenance and replacement thereof, especially in view of the assembly of separate moving parts that is required.
One field of application in which it is necessary to repeatedly couple and uncouple a shaft head with one or more mating hubs is in measuring the unbalance of rotating bodies and then carrying out a balancing of the rotating bodies. A particular example is the unbalance measuring and balancing of torque converters used in the drive trains of motor vehicles and the like. Before its final installation, a torque converter must be balanced to ensure proper and smooth operation thereof. Very generally, such a torque converter comprises inner parts including a turbine, a clutch plate and a stator arranged within an outer shell. The is inner parts have typically been pre-balanced during manufacturing and assembly thereof. The outer shell, however, needs to be balanced in a final balancing step. To achieve this, a balancing machine includes a first tooling that couples to the outer shell and a second tooling that couples to the inner parts and especially the turbine. Typically, the first tooling is connected to a lower drive, while the second tooling is connected to an upper drive, which then respectively rotate the outer shell and the inner parts respectively through the first tooling and the second tooling, about a vertical rotation axis.
For measuring the unbalance of the outer shell, the outer shell and the inner parts are both rotated together, by means of the first tooling and the second tooling as mentioned above. Hereby it is critical that the inner parts must be held very “still” relative to the outer shell. In other words, while the inner parts are freely rotatable relative to the outer shell, during the unbalance measuring, the inner parts must be rotated exactly in synchronism with the outer shell, so that there is no relative rotation between the inner parts and the outer shell. During this rotation, the unbalance of the torque converter unit is measured by any conventionally known method and means, generally based on the radial forces exerted by the rotating body as it rotates. Then, the inner parts are rotated or rotationally offset by 180° relative to the outer shell and thereafter once again the outer shell and inner parts are rotated together in perfect synchronism, and the overall unbalance of the torque converter unit is measured a second time. By comparing the two unbalance measurement results, the unbalance of the outer shell itself can be derived or calculated.
Then, the unbalance data are used to control a balancing procedure, for example by removing material from or adding material to the outer shell at appropriate locations to balance out the outer shell. A further unbalance measurement procedure, or so-called audit run, is carried out after performing the balance corrective steps to ensure that the balancing steps did actually achieve a proper balancing of the outer shell.
The above application of torque converter balancing places high demands on the splined shaft head of the second tooling that engages the inner parts of the torque converter. Namely, since this balancing operation must be carried out on every torque converter, the balancing equipment tooling, and particularly the splined shaft head, is repeatedly engaged with and disengaged from the respective splined openings or hubs of successive torque converters that are to be tested and balanced in a series production manner. This leads to rapid cumula

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