Small cross-section bearing unit

Abstract

A small section bearing unit having a flanged outer race (20), an inner race (30) coaxial with said outer race (20) and with an axis of rotation (X), a plurality of rolling elements (40) arranged between said inner race (30) and said outer race (20) to allow the relative rotation of said inner race and said outer race about said axis (X), and sealing means (50) for preventing the entry of contaminants and at the same time preventing the leakage of lubricating grease from the inside of said bearing unit (10); said sealing means (50) being provided on each side (L) of said bearing unit (10) with a shaped sealing barrier (51) rotatably supported by said outer race (20) about said axis (X) and with a labyrinth seal (52) extending along a respective complex serpentine path (P) defined by the associated sealing barrier (51) and by said inner race (30).

Description

Technical Field

[0001] This invention relates to a bearing unit with a small cross-section. Background Technology

[0002] Known types of small-section bearing units are suitable for applications where the axial dimensions are very compact or where weight must be limited, and typically include: an outer ring; an inner ring; multiple rolling elements configured between the inner and outer rings to allow the inner and outer rings to rotate relative to each other about an axis of rotation; and sealing devices on each side of the bearing to prevent contaminants from entering the bearing unit while preventing grease from leaking from the interior of the bearing unit.

[0003] Because the bearing units of the above types can have very small axial dimensions, they can be advantageously used in marble cutting machines. The processing action of marble cutting machines generates very fine grinding dust, which can easily penetrate into the bearing unit, thereby significantly reducing the service life of the bearing unit. Summary of the Invention

[0004] The purpose of this invention is to provide a small cross-section bearing unit that, while maintaining its basic thinness, also has a long service life, especially when used in aggressive environments (such as marble cutting machine environments).

[0005] According to the present invention, a small cross-section bearing unit having the features set forth in the appended claims is provided. Attached Figure Description

[0006] The invention will now be described with reference to the accompanying drawings, which illustrate non-limiting examples of embodiments of the invention, in which:

[0007] Figure 1 This is a perspective view of a preferred embodiment of the small-section bearing unit according to the present invention;

[0008] Figure 2 Shown at a larger scale and in cross-section according to Figure 1 The bearing unit; and

[0009] Figure 3 It shows the proportion of the data according to the data. Figure 2 Details of the small cross-section bearing unit. Detailed Implementation

[0010] Reference Figure 1 and Figure 210 represents a bearing unit having a small cross-section and therefore a very compact axial dimension, and the bearing unit includes: a flanged outer ring 20; an inner ring 30 coaxial with the outer ring 20 and the axis of rotation X; and a plurality of rolling elements 40 (preferably balls) disposed between the inner ring 30 and the outer ring 20 to allow the inner ring 30 and the outer ring 20 to rotate relative to each other about the axis X.

[0011] Throughout this specification and in the claims, terms and expressions indicating position and direction (such as “radial,” “axial,” or “lateral”) shall be understood to refer to the axis of rotation X.

[0012] In the bearing unit 10 according to the invention, the flanged outer ring 20 is a rotating ring and is provided with a central radial inner raceway 21 for the rolling element 40. An annular recess 22 is provided on each side L of the bearing unit 10. The annular recess 22 opens radially toward the axis X and axially toward the outside of the bearing unit 10. It is formed in the flanged outer ring 20, extends from a corresponding outer annular surface 23 that defines the flanged outer ring 20 axially, and is defined radially toward the outside (outer side) of the outer ring 20 by a cylindrical surface 24, and axially toward the inside (i.e., toward the raceway 21) by an annular surface 25 transverse to the axis X. Two annular recesses 22 are arranged axially on opposite sides of the raceway 21 and are mirror images of each other.

[0013] In the bearing unit 10 according to the invention, the inner ring 30 is a non-rotating ring and is provided with a central radial outer raceway 31 for the rolling element 40, the central radial outer raceway 31 facing the raceway 21 radially. On each side L of the bearing unit 10, the inner ring 30 is defined axially by two annular surfaces 32 and 33, the annular surfaces 32 and 33 being continuously arranged from the outside of the bearing unit 10 toward the axis X, and the two surfaces 32 being axially recessed (inset) relative to the surface 33, the surface 33 being substantially aligned axially with the surface 23 of the outer ring 20. Furthermore, on each side L of the bearing unit 10, the inner ring 30 is defined radially by two cylindrical surfaces 34 and 35, which are continuously arranged from the outside of the bearing unit 10 toward the axis X. Two of these surfaces 35 are directly disposed on opposite sides of the raceway 31 and are defined axially toward the outside (outer side) of the bearing unit 10 by surface 32; while surface 34 is defined axially toward the outside of the bearing unit 10 by surface 33. Finally, again on each side L of the bearing unit 10 and as... Figure 3As shown more clearly in the diagram, the inner ring 30 includes cylindrical lateral grooves 36 formed axially across the surface 33 toward the interior of the bearing unit 10: each groove 36 is defined radially toward the interior (i.e., toward the axis X) by an associated surface 34, radially toward the exterior (i.e., the opposite side relative to the axis X) by a tapered surface 37, and finally axially toward the interior (or inner side) of the inner ring 30 by an annular surface 38, wherein the tapered surface 37 appears and gradually opens toward the associated surface 33, and the annular surface 38 is transverse to the axis X and intercepts surfaces 34 and 37 (or intersects with both surfaces 34 and 37), preferably but not necessarily, the annular surface 38 also connects to surfaces 34 and 37.

[0014] According to the invention, the small cross-section bearing unit 10 further includes a sealing device 50 for preventing contaminants from entering the interior of the small cross-section bearing unit 10 (i.e., between raceways 21 and 31 where the rolling element 40 travels) and for preventing grease from leaking out of the interior of the bearing unit 10 again. On each side L of the bearing unit 10, the sealing device 50 includes: a corresponding shaped screen 51, which is rotatably supported by an outer ring 20 about axis X; and a corresponding labyrinth seal 52, which, as will be described more clearly below, is defined by each screen 51 and an inner ring 30.

[0015] Each shield 51 includes two annular edges 53 and 54 having ends with a generally L-shaped cross section, wherein edge 53 is a radially outer edge and engages within an associated annular recess 22 such that it is keyed to an associated outer annular surface 23 and positioned axially against an associated annular surface 25, while edge 54 is a radially inner edge and freely (i.e., without any contact) inserts into an associated groove 36. Specifically, each edge 53 includes a corresponding cylindrical portion 55 and a corresponding flanged portion 56, the cylindrical portion 55 being bonded to the associated surface 23, the flanged portion 56 being transverse to (or tangential to) the axis X and arranged to axially abut against the associated annular surface 25, and each edge 54 including a corresponding flanged portion 57 and a corresponding cylindrical portion 59, the flanged portion 57 being transverse to the axis X, substantially coplanar with the associated surface 23 in the axial direction, and connected to the associated flanged portion 56 via a tapered portion 58, the cylindrical portion 59 being freely supported at the end of the flanged portion 57 opposite to the end connected to the tapered portion 58.

[0016] Each edge 53, together with the inner ring 30 (and particularly with the associated groove 36), defines a corresponding multi-stage labyrinth seal 52, which includes:

[0017] - The corresponding radial annular inner section ( / stage / step) and / or channel 61 communicate with the interior of the bearing unit and are axially defined by the associated flanged portion 57 and the associated surface 32.

[0018] - The corresponding radial cylindrical outer section and / or channel 62 communicates with the outside of the bearing unit and is radially defined by the associated cylindrical portion 59 and the associated surface 34, and

[0019] - The corresponding intermediate forming section and / or channel 63, between the associated annular channel 61 and the associated channel 62, and defined by the associated cylindrical portion 59 and by the associated surfaces 37 and 38.

[0020] Due to the specific construction of the bearing unit 10 and the shielding members 51, the segments and / or channels 61, 63, and 62 have very small openings, making them particularly difficult to penetrate ( / permeate), i.e., they have a high sealing capability capable of preventing contamination ( / decontaminants) from the outside of the bearing unit 10. Furthermore, the innovative construction of each shielding member 51 and its free positioning within the associated groove 36 results in a series of segments and / or channels 61, 63, and 62 along a relatively complex and particularly meandering path P, as mentioned so far, which is not only difficult to penetrate but also cannot be easily traversed by grease contained within the bearing unit 10, thus preventing any leakage of grease. Essentially, both the linear extension of the path P and the very small openings of the segments and / or channels 61, 63, and 62 contribute to the ability to retain grease within the bearing unit 10, because these two factors, characteristic of the invention, contribute to increasing the head loss of grease along the path P, i.e., helping to particularly prevent grease leakage from the bearing unit 10. It should also be emphasized that, during use, the sealing capability of each labyrinth seal 52 is further increased by the relative movement of the associated shaped shield 51, which is rotatably supported by the outer ring 20 about axis X, relative to the non-rotating (fixed) inner ring 30. This relative movement generates a centripetal force (or centripetal effect) at least within the segments and / or channels 61 and 63, which helps to push the grease into the interior of the bearing unit 10, thus preventing any grease leakage.

[0021] To further enhance the advantages of the invention, namely, particularly to further increase the grease retention capacity and the utilization of the relatively long extension of the path P, along the portion defined by surface 37, the channel 63 has a section inclined with an average inclination that decreases from the outside of the bearing unit 10 relative to the axis X, and further increases the force that pushes the grease into the interior of the bearing unit 10.

[0022] As can be clearly seen from the above, by creating a path P that advantageously utilizes the interconnection of each edge 54 with the associated groove 36 extending axially inside the inner ring 30, or more precisely, by creating a path P that advantageously utilizes the interconnection of the portion of edge 54 defined by portion 59 with the associated groove 36 extending axially inside the inner ring 30, a relatively long path P of the labyrinth seal 52 can be created without increasing the axial width of the bearing unit 10. Thus, the axial width remains particularly small and suitable for the intended use of the bearing unit 10.

[0023] It should be understood that many other variations are possible besides the embodiments of the invention described above. It must also be understood that the embodiments described are merely examples and do not limit the subject matter, application, or possible constructions of the invention. Rather, while the description provided above enables those skilled in the art to implement the invention at least in one example of its construction, it must be understood that many variations of the described components are possible without departing from the scope of the invention as defined in the appended claims, interpreted literally and / or according to their legal equivalents.

Claims

1. A small-section bearing unit, comprising a flanged outer ring (20), an inner ring (30) coaxial with the outer ring (20) and a rotation axis (X), a plurality of rolling elements (40) disposed between the inner ring (30) and the outer ring (20) to allow the inner ring and the outer ring to rotate relative to each other about the axis (X), and a sealing device (50) for preventing contaminants from entering and simultaneously preventing grease from leaking from the interior of the bearing unit (10); the bearing unit (10) is characterized in that the sealing device (50) comprises on each side (L) of the bearing unit (10): The molded sealing shield (51) is rotatably supported by the outer ring (20) about the axis (X); And the labyrinth seal (52), extending along a corresponding complex meandering path (P) defined by the associated sealing shield (51) and the inner ring (30), Each labyrinth seal (52) is a multi-segment labyrinth seal, the multi-segment labyrinth seal including a corresponding intermediate forming segment (63), the intermediate forming segment (63) being provided with a portion inclined relative to the axis (X) at an average inclination decreasing from the outside of the bearing unit (10), such that the distance between the tapered surface (37) of the inner ring defining the intermediate forming segment (63) and the radially outer surface of the radially inner end of the forming seal shield (51) varies with a value corresponding to the average inclination. The molded sealing shield (51) has an annular edge (53) on the radially outer side, the annular edge (53) being mounted in the annular recess (22) of the outer ring (20) and including a cylindrical portion (55) and a flanged portion (56), the cylindrical portion (55) abutting against the cylindrical surface (24) of the annular recess (22), the flanged portion (56) abutting against the radial annular surface (25) of the annular recess (22), and the axially outer end face of the cylindrical portion (55) being substantially aligned axially with the radially outer surface (23) of the outer ring (20).

2. The small cross-section bearing unit according to claim 1, characterized in that, The inner ring (30) includes a groove (36) on each side (L) of the bearing unit (10), the groove being formed across a first outer surface (32) of the inner ring (30) and defined radially toward the interior by a corresponding first cylindrical surface (34); the corresponding end of the associated shield (51) is combined with the inner ring (30) to define an associated path (P) and is freely inserted into the associated groove (36) to give the path (P) a complex and meandering construction.

3. The small cross-section bearing unit according to claim 2, characterized in that, Each labyrinth seal (52) includes a corresponding inner radial section (61) communicating with the interior of the bearing unit (10) and a corresponding outer radial section (62) communicating with the exterior of the bearing unit (10), the inner radial section and the outer radial section being arranged along the path (P) on opposite sides of the associated shaped section (63); the inner radial section (61), the outer radial section (62) and the shaped section (63) have very small openings and together contribute to extending the length of the path (P).

Images