Rotary shafts – gudgeons – housings – and flexible couplings for ro – Coupling accommodates drive between members having... – Coupling transmits torque via radially directed pin
Reexamination Certificate
1996-10-28
2001-02-06
Walsh, Donald P. (Department: 3653)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Coupling accommodates drive between members having...
Coupling transmits torque via radially directed pin
C464S011000, C464S136000, C277S377000
Reexamination Certificate
active
06183369
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a cross member unit for universal joints. The cross member unit has a cross member with four arms. Each two arms define a common longitudinal axis and each arm has an end face. A cylindrical bearing face adjoins the end face which, in turn, is followed by a sealing face and furthermore a seat portion. A bearing bush is provided per arm. The bearing bush includes a tubular, cylindrical casing whose inner face is designed as a running face. The bearing bush is arranged coaxially around the arm with an annular gap. The bearing bush has a base which covers the arm end face and the bearing bush open end includes a running face. Rolling contact members, in the form of rollers or needles, are rollingly arranged in the annular gap. The rollers or needles form a ring around the arm on the running face of the arm and on the inner face of the casing. An annular main seal is firmly inserted into the bearing bush from the open end. The seal includes at least one sealing lip to seal the sealing face of the arm. An annular preseal is arranged on the seat portion of the arm. The preseal includes a sealing lip to sealingly rest against the running face provided at the open end of the bearing bush.
A cross member unit is described in EP 03 21 076. Here, the main seal is fixed to the inner face of the bearing bush by means of a metallic carrier. The seal has two sealing lips. One lip sealingly rests against a cylindrical sealing face of the cross member arm. The other lip rests against a conically extending sealing face of the cross member arm. Furthermore, a preseal is provided in the form of an angle ring arranged on a cylindrical face of the arm. The cylindrical face adjoins the sealing face for the sealing lips of the main seal. The preseal extends over the outer face of the bearing bush by means of a leg which extends parallel to the inner face of the bearing bush. Together with an inwardly directed bead engaging a groove in the outer face of the bearing bush, the preseal forms a labyrinth seal. Friction contact does not exist between the bearing bush and the preseal. However, the preseal itself is positioned, through friction contact, on the associated seat portion of the arm of the cross member.
An improved embodiment of such sealing assemblies with a main seal and preseal for relubricatable cross member units is described in DE 88 05 833 U1. Here, the main seal is firmly inserted into the bearing bush and is provided with two sealing lips. The lips seal a cylindrical sealing face of the cross member. The preseal is arranged, via an annular portion, on a cylindrical portion of the cross member. The cylindrical portion constitutes an extension of the sealing face for the sealing lips of the main seal. The preseal is supported on a curved face, if viewed in the axial direction of the arm. Furthermore, starting from said first leg used for fixing the preseal on the arm, the preseal includes a second leg which is arranged at a radial distance, with reference to the longitudinal axis, and is connected to the first leg by a web. Also, the second leg externally extends over the bearing bush.
All the above embodiments are disadvantageous in that there is no defined seat for the preseal on the cross member arm. Thus, there may be an increase in wear and leakages may also occur. The preseal is able to rotate on the arm, which means that the preseal fit progressively loosens. It is possible for lubricant to leak out and if the seal moves on the seat face, it may be destroyed.
In the case of commercial vehicles, especially high performance vehicles, the objective is to reduce maintenance periods to a minimum. If possible, it is desirable to guarantee a predetermined maintenance-free service life. The service life, in the case of commercial vehicles, is approximately 1 million kilometers. In particular, this applies to vehicles with a permitted gross vehicle weight of more than fifteen (15) tons.
SUMMARY OF THE INVENTION
It is an object of the invention to propose a cross member unit for universal joints with improved service life. Thus, it is desirable to guarantee a high running performance for vehicles with driveshafts including universal joints with such cross member units.
In accordance with the invention, a seat portion of the arm includes a cylindrical seat portion. Starting from the seat portion, viewed in a section containing the longitudinal axis, a curved seat portion extends curve-like away from the longitudinal axis. The preseal has a bore which includes a first bore portion with at least one continuous bead which projects radially inwardly towards the longitudinal axis. The first portion positions the preseal on the seat portion in a pretensioned way. The first bore portion, in the unfitted or untensioned condition, leaves an open aperture which is smaller than the diameter of the cylindrical seat portion of the arm. Furthermore, the bore of the preseal includes a second bore portion adapted to the way in which the curved seat portion of the arm extends.
A firm fit is achieved by providing at least one bead arranged on the cylindrical seat portion. The pretension which holds the preseal on the cross member arm may be determined by the dimensions of the first bead. If one bead is not sufficient, it is possible to provide a plurality of beads arranged parallel relative to one another. In this way, static sealing is ensured between the preseal and the arm. Accordingly, the conditions of movement are clearly defined. The unit, which includes a cross member arm and preseal, moves relative to the bearing bush fixed in the yoke bore of the yoke arm in the region provided for a contact seal and in the region of the sealing lip which is in contact with a corresponding stop face at the open end of the bearing bush. It is thus possible to achieve clearly defined sealing conditions. Further, the preseal remains in its position even if axial forces occur, no positional changes occur in the axial direction which would have negative effects on the service life of the sealing lip, which has a sealing function relative to the bearing bush. In consequence, the pretensioning conditions remain constant at the sealing lip sealing the running face at the open end of the bearing bush. Furthermore, the shape of the seat portion ensures that the pretension cannot result in axial forces which may displace the preseal.
In addition, the preseal is slid into its end position on the seat portion. The end position is necessary to enable the sealing lip to assume its predetermined position relative to the running face at the bearing bush.
In a further embodiment of the invention, the second bore portion is arranged in a pretensioned way on the curved seat portion. However, because of the high pretension achieved by the beads, it is unable to displace the preseal. In a preferred embodiment, the first bore portion of the preseal is associated with two beads. To maintain the high pretension over a long period, it is also proposed that the preseal include an elastomer material and a metal reinforcement insert.
According to a further embodiment, the preseal is U-shaped in a sectional plane containing the longitudinal axis to ensure that the required pretensioning conditions of the preseal relative to the arm, on the one hand, and the required pretension of the sealing lip relative to the running face of the bearing bush, on the other hand, are independent of one another. The first leg closest to the longitudinal axis includes the bore. The bore positions the preseal on the seat portion of the arm. The outer second leg, connected to the first leg by a web, includes the sealing lip which is intended to rest against the stop face of the bearing bush.
To ensure that the preseal together with the bearing bush and the main seal can be fitted in one operation, in a further embodiment of the invention, the main seal includes an annular metallic carrier or a reinforcing insert which projects from an open end of the bearing bush in the direction of the preseal. The carrier or inse
Faulbecker Gerd
Meineke Manfred
Sedlmeier Rolf
GKN Automotive AG
Harness & Dickey & Pierce P.L.C.
Marcelo Emmanuel M.
Walsh Donald P.
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