Rotary shafts – gudgeons – housings – and flexible couplings for ro – Housing
Reexamination Certificate
1998-03-27
2001-04-03
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Housing
C464S905000
Reexamination Certificate
active
06210282
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an outer joint part of a constant velocity universal joint which comprises an externally cylindrical casing part whose inside is provided with tracks to allow the engagement of torque transmitting elements, and which further comprises a substantially annular flange part which is provided with a central inner recess and which is slid on to the casing part and connected thereto, as well as provided with circumferentially distributed fixing holes for threading on a counter flange.
An outer joint part of this type is known from DE 43 14 503 C1. Between fixing portions having circular-arc-shaped outer edges, there are provided concave connecting portions and which have a smaller radial dimension than the fixing portions. The casing part and flange part are joined by a continuous weld.
In the attempt to save weight, outer joint parts of the above-mentioned type become more and more thin-walled. In some cases, outer joint parts which used to be exclusively forgings or hot-formed parts are now produced from plate metal by cold forming processes.
Even if a suitable material is selected, such thin-walled outer joint parts are easily deformable. One of the main objectives of modern forming processes consists in finish-producing the guiding tracks of the outer joint parts in the course of the forming operation which, at most, are followed by surface treatment processes.
This method is risky in that during subsequent assembly of the flange parts, the casing part of the outer joint part may be subject to deformation resulting in inaccuracies in the previously accurately produced guiding tracks. The measures of providing increased accuracy in producing the flange parts or of machining the seat faces for the flange parts at the casing part, which would prevent this deformation, are undesirable because of the additional costs.
It is therefore the object of the present invention to provide an outer joint part of the initially mentioned type which makes use of the advantages of a cost-effective production process without allowing any defects in the dimensional accuracy of the guiding tracks during the assembly of the casing part and flange part.
SUMMARY OF THE INVENTION
The solutions proposed to achieve the above objective are all characterized in that the flange part comprises circumferentially distributed, individual, separate fixing portions which receive the fixing holes, and connecting portions which connect the fixing portions and have a greater flexibility than the fixing portions. Furthermore, according to a first embodiment, it is only in the region of the fixing portions where the flange part is welded to the casing part. According to a second embodiment, the connecting portions are provided with apertures or slots. According to a third embodiment, the connecting portions comprise parts whose wall thickness is reduced as compared to that of the fixing portions. According to a fourth embodiment, the connecting portions comprise folds which project from the plane of the fixing portions. In the case of the second and further embodiment, the flange part can be continuously welded to the casing part.
These methods make it possible to fully utilize the scope available for the lightweight construction of the casing part in respect of the strength values required in operation, and at the same time to ease the requirements in respect of production accuracy, shape of the flange part and production of the respective seat face at the casing part. Even if the conditions of fit are inaccurate, assembly is possible without any distortion occurring in the casing part. The inaccuracies are compensated for by deformations in the regions of the connecting portions. Even with relatively large production tolerances, classification of the casing parts and flange parts is not required. By connecting the casing part and flange part, the casing part acquires the stiffness needed in operation. After the flange part has been slid on to the casing part, the connecting portions, in the case of press fits, are able to reduce forces as a result of their flexibility and, in particular, to bias non-uniform forces by means of deformation.
The dimensions of the connecting portions can be reduced in such a way that they can be regarded entirely as means for connecting the individual fixing regions to one another, in order to facilitate assembly. The individual fixing regions are stiffened relative to one another by being welded to the casing part and by being fixed to a sufficiently stable counter-flange.
To reduce the forces during press-fit assembly, knobs are preferably provided in the inner recess of the flange part, which knobs project inwardly beyond a continuous contour, or to provide knobs at the casing part in the region of the seat face for the flange part, which knobs project beyond a continuous outer contour. Such knobs are more easily deformable than the connecting portions, so that part of the forces or peak forces occurring during assembly are reduced immediately. The gap existing between the contact points in the regions of the knobs is preferably closed by a weld. The knob height is preferably small enough to allow the gap to be closed by laser welding.
Special embodiments of the connecting portions are described in the sub-claims to whose contents reference is made hereby. In particular, reference is made to the special description of the drawing. The fixing portions may preferably comprise one or two fixing holes each. In a preferred embodiment, there should be provided three or more fixing portions.
REFERENCES:
patent: 4523916 (1985-06-01), Kizler et al.
patent: 5279522 (1994-01-01), Rouillot et al.
patent: 5407296 (1995-04-01), Brown
patent: 5676599 (1997-10-01), Ricks et al.
patent: 5857800 (1999-01-01), Nell
patent: 4314503 (1994-12-01), None
patent: 2200722 (1988-08-01), None
patent: 9116550 (1991-10-01), None
Binda Greg
Browne Lynne H.
GKN Lobro GmbH
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