IT201800004583A1 - HIGH PRECISION ANGULAR CONTACT ROLLING BEARING - Google Patents

Description

Description accompanying a patent application for industrial invention entitled: HIGH PRECISION ANGULAR CONTACT ROLLING BEARING

On behalf: Aktiebolaget SKF

5 by nationality: Swedish

based in: 415 50 Goteborg (SWEDEN)

Designated inventors: Franken, Mark (NL);

Greco, Feliciano (IT);

Wang, Jun (CN); And

10 Van den Kommer, Albert (NL)

DESCRIPTION

Technical Sector of the Invention

The present invention relates to a high precision 15 angular contact rolling bearing, in particular a bearing for machine tool spindles and / or other applications for which its use is recommended (for example, wheel hubs vehicles, electric motors, turbomolecular pumps, stabilizing gyroscopes for boats). By vehicle we mean a common motor vehicle, but also a high-performance 20-performance sports vehicle. The present invention is focused on improving the useful life of the lubricating grease present inside the bearing.

Technique Note

The wheel hubs of known types of motor vehicles, in particular sports motor vehicles, comprise an assembly which includes a rolling bearing 25 in angular contact with a single ring of elements of

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201800014-IT Dr. Mag. Ing. LUCA TEDESCHINI (9398) rolling. In applications such as machine tool spindles, high precision angular contact bearings are used due to the tight manufacturing tolerances necessary to guarantee the high performance required. The rolling bearing is generally mounted, 5 normally in groups or sets of identical bearings, on the spindle, intended as shaft and housing, of the machine tool which performs chip removal machining. The angular contact rolling bearing comprises a radially inner ring, a radially outer ring and a series of balls between the rings, held in position by a cage. 10 The lubrication of angular contact bearings is entrusted to the grease which is inserted in a certain percentage (normally around 15%) of the free volume present between the rings of the bearing around the crown of balls and the relative cages.

Bearings of this type, especially high-precision ones, suffer from a limited life 15 due to the exhaustion of grease, especially, as in the case of "premium" applications, when the speed exceeds the value around 1 , 5 million ndm (that is, number of revolutions per minute multiplied by the value of the mean diameter of the bearing).

A possible solution is that of "relubricating" the bearing, or 20 that of inserting new grease through holes suitably prepared on the radially outer ring of the bearing. This solution, apparently obvious, however, involves a series of disadvantages. In fact, such a procedure is complicated and expensive because it is necessary to provide at least one pump with the relative ducts in order to carry out the re-lubrication.

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201800014-IT Dr. Mag. Ing. LUCA TEDESCHINI (939B) There is therefore the need to define a new high precision angular contact bearing, for which the useful life of the grease is no longer a limit to the useful life of the entire bearing.

Summary of the Invention

5 The object of the present invention is to provide an angular contact rolling bearing which is free from the drawbacks described above. In particular, an aspect of the present invention relates to the arrangement of the grease inside an angular contact bearing, in particular with high precision. In this way the result of 10 prolonging the useful life of the grease is obtained even in applications characterized by high speed operation.

The solution consists in providing a reserve of fat in addition to the volume normally inserted. The grease is positioned in the space between the radially outer ring inlet and the cage 15 and in particular, in the volume available between one sphere and the next, up to near the beginning of the track. In this way, the grease releases the oil present inside it, providing lubrication of the bearing.

Advantageously, the fat reserve is the same amount as the volume of fat commonly fed into the cavity. Therefore, the volume of available grease 20 is doubled and consequently the useful life of the grease and of the bearing is increased without the need for any relubrication.

Even more advantageously, the grease reserve can be inserted in a circumferential groove positioned at the mouth 25 of the radially outer ring, made according to an embodiment

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201800014-EN Dr. Mag. Ing. LUCA TEDESCHINI (939B) different from the outer ring. In this way the overall volume of available fat is further increased.

According to the present invention, an angular contact rolling bearing is provided having the characteristics set out in the appended independent claim 5.

Further preferred and / or particularly advantageous embodiments of the invention are described according to the characteristics set out in the attached dependent claims.

Brief Description of the Drawings

10 The invention will now be described with reference to the attached drawings, which illustrate a non-limiting example of embodiment, in which:

Figure 1 is a section of the angular contact rolling bearing, according to an embodiment of the present invention, and

15 Figure 2 is a section of the angular contact rolling bearing, according to an alternative embodiment of the present invention.

Detailed Description

With reference to Figure 1, the number 30 indicates as a whole a rolling bearing with angular contact, in particular, a rolling bearing with angular contact and high precision for sports cars, provided with axial symmetry with respect to its axis X .

Throughout this description and the appended claims, the terms indicating the positions and directions, such as "radial" or "axial" must be understood as referring to the axis of rotation X. The terminology "axially"

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201800014-EN Dott. Mag. Ing. LUCA TEDESCHINI (939B) internal "or" axially external "refers to a condition of assembly of the bearing unit on the vehicle.

The rolling bearing 30 comprises a radially outer ring 31, stationary, provided with a radially outer raceway 5 32, a radially inner ring 34, rotatable, provided with a radially inner raceway 35. Both rings are of thickness il as small as possible to save weight. The minimum wall thickness of the radially outer ring 31 is about 4.5 mm, while the minimum wall thickness of the radially inner ring 34 10 is about 3.1 mm.

The rolling bearing 30 further comprises a ring of rolling bodies 33, in this example balls. The ring of rolling bodies is interposed between the radially external ring 31 and the radially internal ring 34. For simplicity of graphical representation, reference 15 33 will be attributed both to the individual balls and to the ring of balls.

Again for simplicity, the term "sphere" can be used as an example in the present description instead of the more generic term "rolling body" (and the same reference number will also be used in the attached drawings). It will always be understood that any other rolling body 33 may be used instead of the balls 20 (for example, rollers, conical rollers, rollers, etc.).

The rolling bodies 33 are held in position by a cage 36, made of plastic material. The bearing is lubricated with grease. For example, the lubricant used may be a liti soap grease. 25 Unlike known solutions, in addition to the volume of grease

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201800014-EN Dr. Mag. Ing. LUCA TEDESCHINI (9398) normally required by the specific application and which generally amounts to 15% of the volume available between the bearing rings, the proposed solution consists in providing an additional volume of grease 40 in addition to the volume normally inserted, so that the total volume 5 occupied by the grease is 25-30% of that available between the bearing rings, without prejudice to the volume occupied by the ball ring and the cage. The grease reservoir is positioned in the space between the mouth 37 of the radially outer ring 31 and the cage 36. In this way, the oil present in the grease leaks and lubricates the bearing.

Advantageously, the grease reserve is of the same amount as the volume of grease commonly introduced into the cavity, ie equal to 13-15% of the space available between the bearing rings, without prejudice to the volume occupied by the ring of balls and the cage. Therefore, the volume of available grease 15 is doubled and consequently the useful life of the grease and of the bearing is increased without the need for any relubrication.

The position in which to insert the grease reserve is the same in which the traditional volume of grease is inserted and in any case it is the position in which the grease tends to arrive, due to mechanical effects, in particular centrifugal ones.

Advantageously, the volume of additional grease 40 is positioned at the mouth of the outer ring, on the right in Figure 1, or on the opposite side with respect to the shoulder 38 of the radially outer ring 31 to 25 contain the crown of balls 33.

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201800014-EN <Dr. Mag. Ing. LUCA TEDESCHI NI (9398)> Preferably, but not exclusively, this solution can be used in angular contact bearings of the shielded type. In fact, if the bearing is mounted in a vertical direction, the shield retains the grease which would otherwise escape due to the force of gravity. Obviously, the same solution is also applicable to unshielded bearings.

Since the additional grease is introduced only in the volume between the mouth 37 of the radially outer ring 31 and the cage 36, the same position in which, as mentioned, the traditional quantity 10 is introduced, all the grease inside the bearing it will not be dispersed but will work and contribute to the extension of the useful life of the grease itself. By introducing more fat, the life of the fat will be further increased.

With reference to Figure 2, a preferred embodiment 15 of the invention is described. The rolling bearing 130 comprises a radially outer ring 131, stationary, a radially inner ring 34, rotating, and a ring of rolling bodies 33, also in this example balls. The radially outer ring 131 differs from that illustrated in Figure 1 in that it has a circumferential groove 132, 20 positioned at the mouth 37 of the radially outer ring 131 and on the opposite side with respect to the shoulder 38 of the outer ring 131. Obviously, the fat reserve can be inserted in the throat 132. The quantity of the fat reserve is further increased compared to the solution of figure 1, since an additional volume, 25 the volume of the throat 132, is made available for be filled with

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201800014-IT Dr. Mag. Ing. LUCA TEDESCHINI (939B) fat. With this solution, the total volume of grease reaches up to 45% of the volume available between the bearing rings (without prejudice to the volume occupied by the crown of balls and the cage) according to the configuration of figure 1, i.e. in the absence of the groove 132.

5 In addition to the ways of implementing the invention, as described above, it should be understood that there are numerous further variants. It must also be understood that said embodiments are only examples and do not limit the object of the invention, nor its applications, nor its possible configurations.

10 On the contrary, although the above description makes it possible for the skilled person to carry out the present invention at least according to an exemplary configuration thereof, it must be understood that numerous variations of the components described are conceivable, without thereby departing from the object of the invention, as defined in the 15 appended claims, interpreted literally and or according to their legal equivalents.

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201800014-EN <Dr. Mag. Ing. LUCA TEDESCHINI (9398)>

Claims (7)

R I V E N D I C A Z I O N I 1. Angular contact rolling bearing (30, 130) comprising a stationary radially outer ring (31, 131), a radially inner rotating ring (34), and a ring of 5 rolling bodies (33 ) interposed between the radially outer ring (31, 131) and the radially inner ring (34) and held in position by a cage (36), the rolling bearing (30, 130) being lubricated with grease, the whose volume is comprised between 13% and 15% of the available volume between the bearing rings, less the volume occupied by the ring of balls (33) 10 and the cage (36), the rolling bearing (30, 130) being characterized by the fact that it is provided with an additional volume of grease (40) so that the total volume occupied by the grease is between 25% and 45% of the available volume between the bearing rings, to less than 15 volum and occupied by the ring of balls (33) and the cage (36). 2. Angular contact rolling bearing (30, 130) according to claim 1, characterized by being of high precision. 3. Angular contact rolling bearing (30, 130) according to claim 1 or 2, characterized by the fact that the volume of additional grease (40) is comprised between 13% and 15% of the volume available between the bearing rings, minus the volume occupied by the ring of balls (33) and the cage (36). 4. Rolling bearing (30) with angular contact according to one 25 of the preceding claims, characterized by the fact that said volume and 1 201800014- I T Dot t. Mag. I ng. LUCA TEDESCHI NI (939B) additional grease (40) is positioned in the space including an opening (37) of the radially outer ring (31) and the cage (36). 5. Rolling bearing (130) with angular contact according to one of claims 1 to 3, characterized by the fact that said volume of 5 additional grease (40) is also positioned in a circumferential groove (132) , obtained in correspondence with the inlet (37) of the radially outer ring (131). 6. Angular contact rolling bearing (30, 130) according to claim 4 or 5, characterized by the fact that said volume of additional grease 10 (40) is positioned on the opposite side with respect to a shoulder (38) of the radially outer ring (31, 131). 7. Angular contact rolling bearing (30, 130) according to one of the preceding claims, characterized in that the bearing is provided with at least one shield. 15 p.i. Akt iebolaget SKF DR. MAG. I NG. LUCA TEDESCHINI (939B) 2 201800014- I T Dot t. Mag. I ng. LUCA TEDESCHI NI (939B)