Joints and connections – Interfitted members – Longitudinally splined or fluted rod
Patent
1991-04-26
1993-05-25
Kundrat, Andrew V.
Joints and connections
Interfitted members
Longitudinally splined or fluted rod
403298, B25G 328
Patent
active
052134377
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is concerned with a serrated-shaft connection between a shaft and a hub with a large number of teeth that are located on the outer circumference of the shaft and on the inner circumference of the hub.
BRIEF DESCRIPTION OF THE PRIOR ART
In known toothed-shaft connections of this kind, the tooth profiles of the teeth of the shaft and the hub are made so that they are always equidistant or nearly equidistant from each other in the meshing zone. In such devices, the tooth profiles or edges are made in straight lines or are involuted in cross section, for example.
If such a known serrated-shaft connection is used in a compressive connection, no uniform compression can be achieved because of the usual toothing deviations. Instead, play or compression that is too high appears in the tolerance limit areas. If there is too much play between the teeth of the shaft and the hub, "frictional corrosion" forms and the connection works loose. If there is too little play--that is, if the compression is too great--the hub becomes locally overelongated. This results in difficulties, for example, when the serrated-shaft connection is used for fastening a detent to a shaft of a vehicle's gear box, because the connection is too loose or the detent's exterior toothing is stretched. Depending upon its cross section, the exterior toothing of the detent also goes partially out of round, which makes assembly and operation of the transmission much harder.
SUMMARY OF THE INVENTION
The object of the invention is to improve the precision of the synchronization of a known serrated-shaft connection without reducing its manufacturing tolerance.
That object is achieved by having the profiles or edges of the shaft teeth and the hub teeth bent differently in such a way that the profiles of the shaft teeth have distances above the top of the teeth that are different from those above the top of the hub teeth.
Owing to the construction of the tooth profiles according to the invention, the compression of the sides can be favorably influenced by selecting an appropriate size and method of securing the bent tooth flank in place and by selecting appropriate materials. Thus, discrepencies of tooth flank shape can be harmlessly compensated and deviations of tooth flank direction and spacing can be compensated for since the defective places resulting from overstraining of material can yield. As a result, the tooth profiles of the shaft and the hub can fit each other. The space between the teeth in the bottom of the hub becomes wider than before without modification of the profile. As a result, improper meshing with the shaft is prevented, and the serrated-shaft connection can be constructed more easily.
If a shaft with conventional toothing is used--with involuted profile, for example--it is advantageous if the tooth profiles of the hub's teeth are bent convexly in cross section. In this case, two convexly bent tooth profiles that can fit each other always meet each other.
The shape of the bent portion of the tooth profiles can be very simply produced geometrically as a section of an arc.
The midpoint of the bent portion of the tooth profiles of the hub teeth lies on the normal line that runs through the point of contact between the tooth profiles of the shaft and the hub. If a measuring device is used for indirect checking of the hub teeth's thickness and the measuring device is made of such a size that its midpoint also lies on the normal line, a precise equalization of the thickness of the hub teeth with the thickness of the shaft teeth is possible because the point of contact between the measuring device and the hub tooth profile coincides with the point of contact between the shaft tooth profile and hub tooth profile.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be explained in greater detail with the help of an embodiment that is represented in the accompanying drawing, in which;
FIG. 1 shows a partial cross section through the serrated-shaft connection according to the invention; and
REFERENCES:
patent: 1779805 (1930-10-01), Dunwoodie
patent: 3836272 (1974-09-01), Duer
patent: 4098096 (1978-07-01), Chard et al.
patent: 4681307 (1987-07-01), Leonard
patent: 4838832 (1989-06-01), Schmitt et al.
Kundrat Andrew V.
Zahnradfabrik Friedrichshafen AG
Zalkind Albert M.
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