Low-friction sealing device and associated rolling bearing

Abstract

Sealing device (1) for a rolling bearing (2), comprising a first shield (21) attached to a radial inner ring (4) of the bearing, a second shield (22) attached between a radial outer ring (5) of the bearing, at least one annular sealing element (23) and a substantially sleeve-shaped, annular, static sealing element (26) arranged between the first shield (21) and the radial inner ring (4) and interacting in a fluid-tight manner with a constant velocity joint (14), wherein the annular sealing element (26) has a side wall (28) provided radially on the inside with at least one groove (29) forming a channel (30) for a direct hydraulic connection between an annular chamber (7) bounded between the inner ring and the outer ring (4, 5) and an empty inner volume (33) of the annular static sealing element (26).

Description

[0001] The present invention relates to a low-friction sealing device, which is designed in particular for use in a wheel hub unit for a vehicle drive wheel, which is intended to be coupled with a constant velocity joint in operation. The invention also relates to a rolling bearing which is provided with such a sealing device and is designed to improve its efficiency. State of the art

[0002] A rolling bearing that forms a wheel hub unit for vehicles can comprise an inner ring that rotates during operation and an outer ring that remains stationary during operation.

[0003] In operation, a vehicle wheel is attached to the inner ring either directly – by means of a first mounting flange that is integrally formed with it – or indirectly – by means of suitable intermediate elements. The outer ring, on the other hand, is usually integrally attached to the vehicle's suspension column, for example by means of a second radial mounting flange that is integrally formed with it.

[0004] A radial annular space enclosed between the inner ring and the outer ring accommodates the rolling elements (for example, balls) which are designed to allow the inner ring and the outer ring to rotate freely relative to each other about a common axis of symmetry.

[0005] To protect the rolling elements from contaminants on the outside of the ring-shaped chamber, such as water, dust and mud, sealing devices are arranged between the inner ring and the outer ring.

[0006] In the case of a wheel hub assembly that may be coupled with a constant velocity joint, the wheel hub assembly, together with the constant velocity joint, forms an arrangement that is completely sealed by means of sealing devices located on both an outer side (outside of the vehicle) and an inner side (inside of the vehicle) of the wheel hub assembly and / or the rolling bearing that forms part of it and / or that substantially constitutes it. The inner sealing device must also be capable of sealing the grooved coupling between the constant velocity joint and the inner ring or spindle of the rolling bearing in a fluid-tight manner.

[0007] If a bearing of the wheel hub unit is assembled in a location with low atmospheric pressure (for example, in a factory located at high altitude), but is then tested or used on a vehicle located in a different location with different, higher pressure conditions (for example, at an altitude lower than where it was assembled, or vice versa), there will be an underpressure or overpressure within the assembled bearing / wheel hub unit compared to the ambient pressure.

[0008] This pressure difference between the bearing's internal volume and the outside atmosphere can lead to numerous disadvantages. For example, a negative pressure can cause increased friction and wear on the sealing lips of the seals that form part of the sealing device, since the atmospheric pressure (which is greater than the bearing's internal pressure) exerts a greater contact force on the sliding contact sealing lips. Conversely, the opposite condition can lead to an undesirable reduction in the contact pressure of the sliding contact lips, resulting in a decrease or loss of sealing capacity.

[0009] DE102018123126A1 attempts to solve this problem by arranging a plastic ring (15) between the seat for the sealing device on the outer ring or on the inner ring and the respective sealing section thereof, which is permeable to air but impermeable to moisture.

[0010] DE102018121469A1, on the other hand, provides for ventilation means that are attached above one of the components of the sealing device, which generally consist of a valve that is provided with a semi-permeable membrane.

[0011] US2022065290A1 even provides for the assembly of the wheel hub unit to be carried out in a sealed chamber.

[0012] All these known solutions are generally complex, expensive and not very efficient; moreover, they require additional elements or multiple process steps, such as assembly in a sealed chamber. Summary of the invention

[0013] The object of the present invention is to provide a sealing device for a rolling bearing and a rolling bearing for a wheel hub assembly equipped with such a sealing device, which do not have the disadvantages of the prior art, and in particular are able to achieve a hydraulic sealing effect without increasing the axial or radial dimensions and without using additional elements, which is independent of the possible pressure variations between the assembly location of the wheel hub unit and the assembly location of the transmission group, which consists of the wheel hub unit and a constant velocity joint coupled to it.

[0014] According to the invention, a sealing device for a rolling bearing and a rolling bearing that is associated with a vehicle wheel hub assembly and is equipped with such a sealing device are provided, as defined in the attached claims. Brief character description

[0015] Further distinctive features and advantages of the present invention will become clear from the following description of two non-limiting embodiments thereof, which are provided with reference to the accompanying drawings, in which: - Fig. Figure 1 shows a radially cut longitudinal view of a transmission group for vehicles in schematic form, consisting of a wheel hub unit and a constant velocity joint, wherein the wheel hub unit is provided with or consists of a rolling bearing according to the invention; - Fig. 2 in schematic form on a larger scale a detail of Fig. Figure 1 shows the constant velocity joint removed; - Fig. Figure 3 shows a schematic detail of a first embodiment of the sealing device according to the invention on a larger scale; - Fig. 4 in schematic form on a large scale the same detail as Fig. 2 shows, but realized in accordance with another embodiment of the sealing device according to the invention, with the constant velocity joint in the coupled position; and - Fig. 5 and Fig. 6 on a larger scale the same detail of Fig. Figure 2 shows, realized in accordance with two possible embodiments of the sealing device according to the invention. Detailed description

[0016] With regard to the Fig. 1 and Fig. 2 designates the reference numeral 1 as a whole a sealing device for a rolling bearing 2, which is designed in particular to form part of a wheel hub unit or arrangement of a generally known type, or consists of one in itself.

[0017] The rolling bearing 2 comprises an inner ring 4 which rotates in use, an outer ring 5 which is stationary in use, and several rolling elements 6 which are housed in a radial annular space or chamber 7 which is bounded between the inner ring 4 and the outer ring 5, so that the inner ring 4 and the outer ring 5 are freely rotatable about a common axis of symmetry A relative to each other.

[0018] In the illustrated, non-restrictive embodiment, the inner ring 4 is provided at its first axial end 8 with a radial flange 9, which extends radially from the inner ring 4 radially outwards to its outer side and faces a corresponding first end 10 of the outer ring 5.

[0019] In the non-restrictive example shown, the inner ring 4 also has a second end 11 ( Fig. 1) opposite the first end 8, to which a retaining ring or “ring piece” 12, forming an integral part of the inner ring 4, is integrally arranged. This end 11 is provided because the present invention is particularly applicable to a wheel hub assembly / unit 3 intended for a drive wheel of a vehicle, with a torque transmission device such as a grooved coupling 13, in the non-limiting example of the front or SFS type. The grooved coupling is connected to a constant velocity joint 14 of the known type (see Fig. 1) - only its external bell element is shown for easier illustration - against which it is held in a stably coupled manner by means of a screw 15 during use.

[0020] On the other hand, the outer ring 5 is integrally provided as one piece on the side opposite its end 10 with a radial flange 16, which extends radially on its outer side and which is designed to be integrally attached in use to a vehicle suspension column, which is known and not shown for the sake of simplicity. Fig. 2 is the constant velocity joint or CVJ shown as a thin dashed line.

[0021] In principle, the rolling bearing 2 shown is of the so-called “third generation” or “double flange” type and itself forms the entire wheel hub assembly 3. However, it is clear that, according to other non-limiting examples of embodiments not shown, the wheel hub assembly or unit 3 could comprise a normal known hub and spindle provided with the flange 9, to which the inner ring 4 is coupled in a known manner, without affecting the general nature of the description provided below. Similarly, the outer ring 5 could be without the flange 14 and configured to be attached to the suspension column 15 in a known manner.

[0022] The annular space or chamber 7 has open opposite axial ends 18 and 19 ( Fig. 1), which are sealed in a fluid-tight manner in use by opposing sealing devices, the end 18 by any known sealing device 20 (in Fig. 1 shown only schematically) and the end 19 through the sealing device 1 according to the invention.

[0023] The sealing device 1 ( Fig. 2 to 6) comprises a first annular shield 21, which is designed to be attached in a known manner, for example by positive locking, at an angle integral to a section or component of the radial inner ring 4 of the bearing 2, in the example shown to the ring piece 12, a second annular shield 22, which is designed to be attached in an angle integral manner in use in one piece to the radial outer ring 5 of the bearing 2 in a position facing the first shield 21, and at least one elastomeric sealing element 23, which is formed one piece with the second shield 22 and is provided with at least one elastically deformable first annular sealing lip 24, which interacts in engagement contact with a sliding / sliding contact surface 25 of the first shield 21.In the attached drawings, the ring-shaped lip 24 is shown in its undeformed state in order to illustrate the engagement arrangement with the surface 25 in a purely schematic way.

[0024] According to one aspect of the invention, the sealing device 1 also includes an annular static sealing element 26, which is essentially shaped as a sleeve and is designed to be inserted in use between the first shield 21 and the radial inner ring 4 (in the example shown, the ring piece 12) of the bearing 2 and to be connected radially to a constant velocity joint on its outer side in a fluid-tight manner.

[0025] The shields 21, 22 have a common axis of symmetry A, which in use coincides with the axis of symmetry of the inner ring 4 and the outer ring 5 of the rolling bearing 2.

[0026] The ring-shaped static sealing element 26 extends axially cantilevered from a first end face 27 of the first shield 21, opposite the second shield 22 and in use facing the constant velocity joint 14.

[0027] According to the main feature of the invention, a side wall 28 of the annular static sealing element 26 is radially provided on the inside with at least one groove 29 ( Fig. 3, Fig. 5 and Fig. 6) provided which is designed to accommodate a hydraulic connecting channel 30 ( Fig. 5 and Fig. 6) to form between a first surrounding volume 31, which adjoins a first end face 32 of the second shield 22, opposite the first shield 21 and the elastomeric sealing element 23, and which in the example shown corresponds to the inner volume which is free (of the spheres 6) from the radial chamber 7, and an empty inner volume 33 of the annular static sealing element 26, which is bounded all around by the side wall 28.

[0028] The groove 29 extends axially beyond the elastomeric sealing element 23 (and all its sealing lips, such as the lip 24) on the side of the first surface 32 of the second shield 22.

[0029] The first surrounding volume 31 is, as already mentioned, defined in use by the interior of the bearing 2, since the sealing device 1 is inserted in use between the inner ring 4 and the outer ring 5 of the bearing 2 in order to close the radial annular volume 7 limited between the inner ring 4 and the outer ring 5 of the bearing 2.

[0030] The groove 29 is also designed to be in direct hydraulic connection with the radial annular chamber 7 during use.

[0031] The empty internal volume 33 of the annular sealing element 26 is also designed to accommodate the constant velocity joint 14 during use.

[0032] According to preferred embodiments of the invention, the side wall 28 of the annular sealing element 26 comprises a first cylindrical annular section 34 which is designed to be angularly integrally connected in use with a radial outer surface 35 of the inner ring 4 (ring piece 12) of the bearing 2.

[0033] The side wall 28 of the annular sealing element 26 also includes a second annular section 36, opposite the first annular section 34 and extending axially outwards from the first cylindrical annular section 34 and terminating in an annular rim 37, which has an annular seal 38 attached to it ( Fig. 4), which is designed to interact radially on the outside of the constant velocity joint 14 in a fluid-tight manner during use.

[0034] The first shield 21 is attached radially to the outside of the annular sealing element 26, in particular to the first cylindrical annular section 34, which in turn, as already indicated above, is attached radially to the outside of the inner ring 4 by a positive fit.

[0035] The first cylindrical section 34 of the annular sealing element 26 has a diameter that is larger than a maximum radial extent of the second cylindrical annular section 36 of the annular sealing element 26.

[0036] In the examples shown, the second annular section 36 of the annular sealing element 26 is also cylindrical and has a diameter that is smaller than that of the first annular section 34 of the annular sealing element 26.

[0037] The annular sealing element 26, apart from the elastomeric seal 38 which is integrally attached to the annular rim 37, is made of metallic or in any case relatively rigid but elastically deformable material, so that the seal 38 can interact with the constant velocity joint 14 with a minimal amount of engagement.

[0038] The second annular section 36 of the annular sealing element 26 extends axially cantilevered from a radially oriented intermediate flange section 39 of the annular sealing element 26, which connects the first and the second annular sections 34, 36 of the annular sealing element 26.

[0039] According to the embodiment of Fig. 5 the at least one groove 29, which is designed to form the hydraulic connecting channel 30, extends axially over the entirety of a cylindrical inner side surface 40 of the first annular section 34 of the annular sealing element 26.

[0040] In a second embodiment ( Fig. 6) The at least one groove 29, which is designed to form a hydraulic connecting channel 30, extends not only axially over the entire axial extent of the radial inner surface 40 of the cylindrical section 34, but also extends radially, with continuity, with its axial section and with the cylindrical inner side surface 40 over a surface 41 of the radial flange section 39 of the annular sealing element 26, which faces its first annular section 34.

[0041] According to this embodiment, the surface 41 actually acts in contact with the inner ring 4, in this case against an annular, stepped end defined by the ring section 12, which serves as the end stop of the sealing element / inner ring coupling 26, 4. In the Fig. In the embodiment shown in 5, however, the surface 41 faces the aforementioned step-shaped end, which is defined by the ring piece 12, but is axially spaced away from it.

[0042] In both embodiments, the continuity of the hydraulic connection between the chamber 7 and the internal volume 33 of the axial annular section 36 of the sealing element 26 is therefore ensured.

[0043] The at least one groove 29, which is designed to form a hydraulic connecting channel 30, is preferably formed by plastic deformation stamping during the shaping of the annular sealing element 26 by means of molds.

[0044] The (axial section of the) at least one groove 29 preferably has two characteristic parameters: - axial length which is greater than that of the counter-surface section of the ring piece 12 on which the annular axial section 34 is attached; - (total) cross-sectional area, measured with the static sealing element 26 attached to the ring piece 12, which is greater than 0.0025 mm (corresponding to a square cross-section of 50 x 50 µm).

[0045] In the case of the in Fig. In the embodiment shown in Figure 6, the groove 29 continues, the area of ​​its cross-section still being larger than 0.0025 mm. 2 beyond the axial extension of the annular section 34 and beyond the stop zone formed by the surface 41, until it reaches the inner volume 33 and consequently the constant velocity joint 14 which is not yet coupled to the wheel hub unit 3 and communicates with the external ambient atmosphere.

[0046] From the above, it is clear that the invention also comprises a rolling bearing 2 for a wheel hub unit 3, comprising an inner ring 4 which rotates in use, an outer ring which is stationary in use, and several rolling elements 6 which are housed in a radial annular space 7 which is bounded between the inner ring 4 and the outer ring 5 in order to make the inner ring 4 and the outer ring 5 freely rotatable relative to each other about a common axis of symmetry A; wherein a first open end 19 of the radial annular chamber 7 is closed by a sealing device as described above;and wherein the at least one groove 29, which is formed radially on the inside of the side wall 28 of the annular static sealing element 26, is formed to form a channel 30 for a direct hydraulic connection between the radial annular chamber 7 and the empty inner volume 33 of the annular static sealing element 26, which is bounded radially on its inside by the second annular section 36, and consequently, when the constant velocity joint 14 is decoupled, with the external ambient atmosphere.

[0047] Finally, the invention also comprises a wheel hub unit / constant velocity joint assembly 3, 14, comprising: the rolling bearing 2 as defined above, which forms part of / constitutes the wheel hub unit 3; and a sealing device 1 in accordance with the one described above, which is arranged to close one end 19 of the radial annular chamber 7, which is bounded between the outer ring 5 and the inner ring 4 of the bearing 2 and faces the constant velocity joint 14; wherein the at least one groove 29, which is formed radially on the inside of the side wall 28 of the annular static sealing element 26, forms a channel 30 for a direct hydraulic connection between the radial annular chamber 7 and the inside of the second annular section 36 of the annular static sealing element 26.

[0048] This second annular section 36 is therefore open to the outside environment when the constant velocity joint 14 is not yet attached, allowing the air pressure inside the chamber 7 to be kept identical to the outside atmospheric pressure due to the channel 30, regardless of where the assembly of the bearing 2 or the wheel hub unit 3 is carried out.

[0049] Conversely, once the constant velocity joint 14 is coupled to the wheel hub unit 3, the chamber 7 is isolated from the outside atmosphere due to the static sealing effect exerted by the sealing element 26 by means of the annular seal 38, with the second annular section 36 being radially attached to the outside of the constant velocity joint 14 in a fluid-tight manner.

[0050] All objectives of the invention have thus been achieved. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102018123126A1

[0009] DE 102018121469A1

[0010] US 2022065290A1

[0011]

Claims

[1] Sealing device (1) for a rolling bearing (2), comprising a first annular shield (21) configured to be integrally attached at an angle to a component (12) of a radial inner ring (4) of the bearing in use, a second annular shield (22) configured to be integrally attached at an angle to a radial outer ring (5) of the rolling bearing in use, in a position facing the first shield, at least one elastomeric sealing element (23) formed integrally as one piece with the second shield (22) and provided with at least one elastically deformable first annular sealing lip (24) which engages in contact with a sliding surface (25) of the first shield (21), and an annular, static sealing element (26) which is essentially formed as a sleeve and configured to be inserted between the first shield (21) and the radial inner ring (4) of the bearing in use. to be,and to be connected radially to a constant velocity joint (24) in a fluid-tight manner, wherein the annular static sealing element (26) extends axially projecting from a first surface (27) of the first shield (21), opposite the second shield (22) and facing the constant velocity joint in use; , characterized by, that a side wall (28) of the annular sealing element (26) is provided radially on the inside with at least one groove (29) which is designed to form a channel (30) for hydraulic connection between a first surrounding volume (22) adjacent to a first end face (32) of the second shield (22), opposite the first shield and the elastomeric sealing element (23), and an empty inner volume (33) of the annular static sealing element (26) which is bounded by its side wall (28), wherein the groove (29) extends axially beyond the elastomeric sealing element (23) on the side of the first surface (32) of the second shield (22). [2] Sealing device according to claim 1, characterized by, that the first surrounding volume (31) in the insert is defined by the interior of the bearing (2), wherein the sealing device (1) in the insert is inserted between the inner ring (4) and the outer ring (5) of the bearing (2) to seal off a radial annular chamber (7) that is bounded between the inner ring (4) and the outer ring (5) of the bearing, wherein the groove (29) in the insert is in hydraulic communication with the radial annular chamber (7). [3] Sealing device according to claim 1 or 2, characterized by , that the empty internal volume (33) of the annular static sealing element (26) is designed to accommodate the constant velocity joint (14) during use. [4] Sealing device according to any one of the preceding claims 1 to 3, characterized by , that the side wall (28) of the annular sealing element (26) comprises: a first cylindrical annular section (34) designed to be angularly integrally connected in use to a radially outer side surface (35) of the inner ring (4) of the bearing; and a second annular section (36), opposite the first annular section (34), which extends axially outwards from the first cylindrical annular section (34) and terminates in an annular rim (37) with an annular seal (38) which is formed, to interact radially on the outside of the constant velocity joint (14) in a fluid-tight manner during use; wherein the first shield (21) is attached radially to the outside of the annular static sealing element (26) on its first cylindrical annular section (34). [5] Sealing device according to claim 4, characterized by, that the first cylindrical annular section (34) of the annular sealing element (26) has a diameter that is larger than a radial extent of the second annular section (36) of the annular sealing element (26); wherein the last extends axially projecting from a radially oriented flange section (39) of the annular sealing element (26) which connects the first and second annular sections (34, 36) of the annular sealing element. [6] Sealing device according to claim 5, characterized by , that the at least one groove (29) which is designed to form a hydraulic connecting channel (30) extends axially over the entirety of a cylindrical inner side surface (40) of the first annular section (34) of the annular sealing element. [7] Sealing device according to claim 6, characterized by, that the at least one groove (29) which is designed to form a hydraulic connecting channel (30) extends radially continuously with the cylindrical inner side surface (40) of the first annular section, also on a surface (41) of the radial flange section (39) of the annular sealing element which faces the first annular section (34) of the annular sealing element. [8] Sealing device according to any one of claims 4 to 7, characterized by, that the second annular section (36) of the annular sealing element (26) is cylindrical and has a diameter smaller than that of the first annular section (34) of the annular static sealing element (26); wherein the latter is made of a metallic or otherwise relatively rigid but elastically deformable material; wherein the at least one groove (29) is formed to create a hydraulic connecting channel (30) obtained by plastic deformation stamping. [9] Rolling bearing (2) for a wheel hub unit (3), comprising an inner ring (4) rotatable in use, an outer ring (5) stationary in use, and several rolling elements (6) housed in a radial annular space (7) bounded between the inner ring and the outer ring to allow the inner ring and the outer ring to rotate freely relative to each other about a common axis of symmetry (A); wherein a first open end (19) of the radial annular space (7) is closed by a sealing device (1) according to any one of the preceding claims 4 to 8; characterized by, that at least one groove (29) formed radially on the inside of the side wall (28) of the static annular sealing element is formed to form a channel (30) for a direct hydraulic connection between the radial annular chamber (7) and the empty inner volume (33) of the annular sealing element (26), which is radially bounded by the second annular section (36) of the side wall (28) of the annular sealing element. [10] Arrangement of a wheel hub unit (3) and a constant velocity joint (14) comprising the rolling bearing (2) according to claim 9, which forms part of / the wheel hub unit (3), and a sealing device (1) according to any one of claims 4 to 8, which is arranged to close one end (19) of the radial annular chamber (7) which is bounded between the outer ring (5) and the inner ring (4) of the bearing and faces the constant velocity joint (14); characterized by, that the at least one groove (29) which is obtained radially on the inside of the side wall (28) of the annular sealing element (26) forms a channel (30) for a direct hydraulic connection between the radial annular chamber (7) and the inside of the second annular section (36) of the annular sealing element (26), wherein the second annular section (36) is fitted radially on the outside of the constant velocity joint (14) in a fluid-tight manner.

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