Hub Bearing Unit Assembly

The present invention relates to bearing construction and more particularly to a hub bearing unit.

In conventional hub bearing units, the inner and outer race rings are unified by a fastening flange, and wherein rows of rolling elements are located between the races. The rolling elements are separated from one another by a cage, and seals for retaining a lubricant are applied. The bearing can be connected to a shaft or to part of the shaft. Such a bearing is described in the French patent specification 2.206.814, for example.

The present invention relates to such types of bearing assemblies, wherein a spline connection between the inner race and shaft is absent, with however optimum drive of the component connected to the inner race still assured. In addition, the proposed improvement provides a favorable stress distribution in the bearing race during loading.

In accordance with the invention, the part of the inner race opposite the flange and outside of the inner diameter -- the so-called head section or end race part -- is provided with elements by means of which the race ring is power transmittably connected to the shaft or to a part of the shaft. In this manner, the prime object is achieved since relatively expensive machining operations such as milling and finish machining of the internal splining on the inside diameter of the inner race as well as the external splining on the shaft itself is avoided, fastening elements being now located on the easily accessible and machinable head section of the bearing race. Moreover, the present invention allows the application of a smooth shaft.

In a preferable embodiment, the fastening elements comprise teeth into which the teeth of a ring-like element fitted over the shaft mesh, or into which teeth formed in the shoulder of a shaft, engage. This provides a reliable fastening of shaft and bearing parts in a simple manner.

The British patent specification No. 1.267.599 discloses a coupling assembly comprising a roller bearing with separated inner race rings, each being provided with teeth meshed or engaged into each other. However, this known assembly completely differs from the hub bearing unit assembly of the present invention in that the race rings herein are unified with fastening flanges to which various wheel parts can be attached directly. Such an assembly shows a different stress distribution in its race rings compared to the bearing parts as applied in the above cited prior art coupling assembly. In addition, the hub bearing unit assembly according to the invention comprises fewer different parts and is very simple in its shape.

According to another important embodiment, the part of the shaft which is connected to the bearing, and which, because of the relatively large inside diameter of the inner race, is provided with a fine thread and lock nut comprising an insert or thrust collar that fits against a smooth or rounded flange outer face. In this matter, clearance in the fastening element between the inner race and shaft can be eliminated by tightening the nut, and, simultaneously, a uniform stress distribution is achieved in the flange and the actual bearing race element.

The invention will now be described by way of an example and with reference to the accompanying drawing, which represents a bearing assembly comprising a bearing 1 and a shaft 2.

The bearing 1 comprises an inner race 3, which at one end passes over into a fastening flange, as well as an outer race 5, which also forms an integral unit with a fastening flange 6. Two rows of rolling elements 7 and 8, pair-off and are separated from one another by a cage 9, and are located between the two race rings 3 and 5. Seals 10 and 11, which are fastened in outer race 5 and are supported at the sealing ends 12 and 13, respectively, on the inner race 3, are attached between the inner and outer races 3, 5. The sealing end 12 rests on the so-called head section 3A of the inner race 3, while the sealing section 13 of seal 11 contacts the inner surface 3B of flange 4. It should be noted that the sealing part 12 can also be placed against the contact surface of the rolling elements 7 instead of against the head section 3A of the race 3 such that the head section 3A can fully be used as a coupling or fastening part 14. In this preferable embodiment, the fastening elements are teeth 14 which can have any suitable shape and preferably made of pressed metal powder like the race. The teeth 14, as shown, face outward from the inner race 3 in a direction paralleling the rotational axis of the shaft 2. The inner surface 3C of race 3 is smooth and rounded or smoothly passes over into the flange side 3D of flange 4. The fact that the radius of curvature R theoretically remains constant for various inside diameters D is favorable. The shaft 2, which is connected to the bearing 1, has a smooth shaft stub 15, which end 16 is provided with a fine thread 16A on which lock nut 17 and a ring 18 are applied. The ring 18 comprises a section 19, which has the same shape as the round or smooth transition section of the inner race 3, such that a relatively large contact area is formed between the ring 18 and transition section of the inner race 3 when the nut 17 is tightened. Tests indicated that, the inner race 3 has a favorable stress distribution, i.e. that high stress concentrations do not occur at the point of contact between the nut 17 and flange surface 3C, 3D when under load. Further, the shafts 2 comprises a shoulder 20 against which a ring 21 with teeth 21A is applied. The teeth 21A mesh into the teeth 14 of the inner race 3. Ringlike element 21 is shrunk fitted on the shaft stub 15, which provides fastening of the shaft to bearing 1 in a simple manner. According to the present invention, the shoulder 20 of shaft 2 itself can also be provided with teeth that mesh directly into the teeth 14 of the inner race 3 instead of having a ring-like element 21 which is shrunk fitted on the shaft stub 15 for fastening purposes.

Further, by using a fine thread 16A on the end part 16 of the shaft stub 15, clearance between the teeth 14 and 21A can be eliminated by tightening the nut 17. Nut 17 is locked against turning on the shaft stub 15 in a known manner, e.g. by a pin 22.

It should be noted that the present invention is not limited to the embodiment as represented, but that all embodiments of a shaft-bearing-arrangement according to the present invention are included that are characterized by a detachable, power-transmitting connection at the so-called head section or race ring end part of the bearing, while the inner race ring surface surrounding the shaft is principally not power transmittably connected to said shaft part.