High emission hub unit

Abstract

A hub unit (102) is provided with a radially outer ring (103) which is stationary during use, a radially inner ring (104) which rotates during use, at least one row of rolling elements (6) interposed between the radially outer ring and the radially inner ring, and a sealing assembly (101) interposed between the radially outer ring and the radially inner ring, which cooperates with the radially outer ring or with the radially inner ring to define a shield of at least one labyrinth seal (22, 122). The labyrinth seal does not have a circumferential symmetry, but comprises an upper portion (22) and a lower portion (122) with respect to an axis of symmetry (A) of the hub unit, and is provided with an angular interruption of the shield formed on the lower portion of the labyrinth seal corresponding to the lower side of the hub unit, so as to increase the outflow from the labyrinth seal of said labyrinth seal, which contributes to the gravitational discharge of the contaminants present inside the sealing assembly.

Description

Technical Field

[0001] This invention relates to a high-drainage vehicle wheel hub unit. Specifically, the wheel hub unit performs high emissions in the area of ​​the sealing assembly of the rolling bearings equipped with the wheel hub unit. Background Technology

[0002] A sealing assembly for a rolling bearing intended to mount a hub unit on the flange side supporting a wheel (so-called "outboard") (such as those described in US8303190 and US2012 / 0177315) consists of a so-called "box" seal. The "box" seal includes a first annular screen and a second annular screen, which have generally L-shaped radial sections and are mounted facing each other to define an annular chamber between the screens. Inside this annular chamber is a series of sealing lips that are mounted on a fixed annular washer (or liner / gasket) integral with one of the screens, which is typically intended to remain stationary during use. External contaminants (water, sludge, dust) entering this chamber are restricted by the special construction of the flange of one or two shields, which also cooperates in a very tight configuration with the outer or inner ring of the bearing and / or the hub element integral therewith, thus forming a labyrinth seal.

[0003] Improved sealing assemblies have been manufactured in which friction caused by sliding contact due to high lip interference has been reduced. Examples of these sealing assemblies are shown in... Figure 1 (As shown in the image) It is equipped with a proper labyrinth seal to ensure a seal against contaminants without the high interference of the sliding contact lip.

[0004] However, this known solution has problems associated with sludge and contaminant discharge. Under operating conditions, labyrinth seals are always affected by sludge flow, which typically seeps in from the top and sides. The sealing assembly is designed to prevent sludge from entering the first chamber of the labyrinth. However, because this sealing system is axially symmetrical, discharge from the lower side may be insufficient to allow sludge to exit the chamber. As a result, the sludge remains trapped, leading to unsatisfactory operation of the sealing assembly.

[0005] One solution to this problem is to use a larger "gap" in the labyrinth seal, for example, by designing one element of a labyrinth seal with a large radius of curvature and an inclination. This improves the drainage on the underside of the hub unit, but the volume of the receiving chamber of the labyrinth seal is reduced in 360 degrees, and therefore the sealing assembly is more easily filled with sludge.

[0006] Therefore, there is a need for a hub unit that can use the low-friction sealing assembly described above, and which is configured to allow high emissions of sludge and common contaminants without adversely affecting the containment capacity of the sealing assembly. Summary of the Invention

[0007] The object of the present invention is to provide a hub unit that does not have the above-mentioned disadvantages and can be provided with the low-friction sealing components or variations thereof as described above. They all share a common characteristic in any case: they operate with minimal interference from the sliding contact lip, and therefore they can also be defined as low-friction.

[0008] According to the present invention, a hub unit having the following characteristics is provided, the hub unit comprising: a radial outer ring, stationary during use; a radial inner ring, rotating during use and having a flange end opposite to the outer ring; at least one row of rolling elements, between the radial outer ring and the radial inner ring; and a sealing assembly, between the radial outer ring and the radial inner ring, wherein the sealing assembly cooperates with the radial outer ring or with the radial inner ring to define a shielding member of at least one labyrinth seal; wherein: the labyrinth seal does not have circumferential symmetry, but includes an upper portion and a lower portion relative to the axis of symmetry of the hub unit, and is provided with an angular interruption of the shielding member formed on the lower portion of the labyrinth seal corresponding to the lower side of the hub unit, thereby increasing the outflow portion of the labyrinth seal from the labyrinth seal itself, which helps to re-entrain contaminants present within the sealing assembly. Force discharge; - The sealing assembly includes: a first shield, stationary during use and having an annular gasket; and a second shield, rotatable during use and provided with a flange terminating at a right-angled bend; and - the radial outer ring has a radially outer surface, and the right-angled bend of the flange extends axially toward an annular groove formed on the radially outer surface of the outer ring between a first cylindrical portion of the radially outer surface of the outer ring and a second cylindrical portion adjacent to the first cylindrical portion, and the right-angled bend has a diameter larger than that of the first cylindrical portion, such that it defines the upper portion of the labyrinth seal with the radial outer ring; an angular interruption of the shield defined on the lower portion of the labyrinth seal by a flat portion of the first cylindrical portion, the interruption having a depth such that it almost eliminates the entire annular groove on the radially outer surface of the radial outer ring.

[0009] According to the present invention, a labyrinth seal assembly, between the outer ring of a hub unit that is stationary during use and the flange portion of a shield integrally formed with an inner ring that rotates during use, or according to a completely similar and dual variation, provides an interruption of the shielding member on the underside of the hub unit between the flange end of the inner ring and the shield integrally formed with the outer ring, thereby facilitating gravity discharge of sludge. Specifically, the labyrinth seal does not have circumferential symmetry, but instead includes an upper and lower portion with symmetrical axis relative to the hub unit, and provides an angular interruption of the shielding member on the lower portion of the labyrinth seal corresponding to the underside of the hub assembly, thereby increasing the outflow section of the labyrinth seal and (thereby) facilitating the gravity discharge of contaminants present within the seal assembly.

[0010] The interruption of the shielding element can be performed on the fixed portion of the bearing (e.g., on the radial outer ring). In this assembly, a discharge opening can be formed, for example, to allow water, sludge, and common contaminants to flow out of the bearing unit. The outflow must occur by gravity; therefore, this opening is positioned vertically on the bottom of the bearing and can extend to varying degrees around the axis. Attached Figure Description

[0011] The invention will now be described with reference to the accompanying drawings, which illustrate two non-limiting examples of embodiments of the invention, wherein:

[0012] - Figure 1 A sealing assembly according to the prior art is shown schematically and in radial section. This sealing assembly is applied to a hub unit of a type not yet known, and therefore only a portion of the hub unit is shown for the sake of a more concise illustration.

[0013] - Figure 2 It is shown schematically and in radial section according to Figure 1 The first embodiment of the present invention applied to a hub unit; and

[0014] - Figure 3 It is shown in schematic form Figure 2 The diagram shows a front view of three possible solutions for the implementation method. Detailed Implementation

[0015] Reference Figure 1 1 represents a low-friction sealing assembly, specifically designed for mounting on a wheel hub unit 2 of a vehicle, wherein the sealing assembly 1 forms an integral part of said unit during use. The description of this known solution as mentioned above is intended to aid in a better understanding of embodiments of the invention.

[0016] The known type of hub unit 2 includes: an outer ring 3, which is stationary during use; an inner ring 4, which rotates about an axis A during use, which is also the axis of symmetry between the rings 3 and 4; and at least one row of rolling elements 6, which are coaxial with each other between the outer ring 3 and the inner ring 4; the ring 4 has a flange end 5 opposite to the outer ring 3 and used to support the wheel.

[0017] The sealing assembly 1 can be inserted into the annular gap 7, which is defined between the rotating inner ring 4 and the stationary outer ring 3 of the hub 2, or more generally, between the rotating element 4 and the stationary element 3 of any known type of universal rolling bearing that forms part of or is integral with the hub unit 2.

[0018] The sealing assembly 1 is located between rings 3 and 4 and inserted into the annular space 7 to protect the rolling element 6 disposed between the fixed element 3 and the rotating element 4. The sealing assembly 1 includes: a first annular screen 10, formed by shearing and pressing a stainless steel sheet; a second annular screen 11, also formed by shearing and pressing a stainless steel sheet, configured to face the screen 10; and an annular gasket 9, made of one or more elastomeric materials, integrally mounted on the screen 11, and provided with a plurality of sealing lips 12, 13, 14, which cooperate with the screen 10 to seal the annular gap 7 and the rolling element 6 in a fluid-tight manner.

[0019] The shielding member 10 is provided with: a first sleeve (or tube) shaped or more generally cylindrical portion 15, which is integral with the rotating element 4 during use; and a first flange portion 16, which extends radially from the sleeve portion 15 on the opposite side of the axis A, and thus extends radially outward from one end 17 of the sleeve portion 15 facing the flange portion 5.

[0020] The shield 11 is provided with: a second sleeve-shaped or more generally cylindrical portion 18, which is integral with the fixing element 3 during use; and a second flange portion 19, which is mounted radially from the sleeve portion 18 on the opposite side of the flange portion 16 and is located facing the flange portion 16; thus, the flange portion 19 extends radially inward from the axial end 20 of the sleeve portion 18 toward axis A and toward the sleeve portion 15. In a non-limiting example of the embodiment shown, the axial end 20 of the sleeve portion 18 points toward the shield 10 and the flange end 5.

[0021] The lips 12 and 13 of the annular gasket 9 extend axially and radially toward the flange 16 in a direction away from the axis A, obliquely relative to the flange 19; furthermore, the flange 16 terminates on the opposite side of the sleeve portion 15 with its radially outer annular portion 21, which extends radially and axially outward outside the annular space 7 during use, such that it defines the first labyrinth seal 22 with the fixed element ( / stationary element) 3.

[0022] In this case, the flange 16 extends radially outward relative to the radially outer surface 23 of the ring 3 on the outer side of the annular space 7.

[0023] An annular portion 21 of the flange 16 is defined / formed by the edge of the flange 16, the edge being bent at a right angle and defining an L-shape facing the axis A in the radial cross section together with the rest of the flange 16.

[0024] During use, the right-angled curved edge 21, together with the flange 16 and the fixing element 3, defines the L-shaped channel 24 in the radial cross section. According to a key aspect of the invention, the L-shaped channel 24 has a substantially constant, but not necessarily identical, width in the radial and axial directions.

[0025] The channel 24 includes: a first branch 25 that forms a labyrinth seal 22 and is defined between the annular portion of the flange 16 or the right-angled curved edge 21 and the first cylindrical portion 26 of the side surface 23 of the outer ring 3; and a second branch 27 that is configured at right angles to the branch 25 and faces the rotating element or inner ring 4 and is defined between the flange 16 and the flat front surface 28 of the fixing element or outer ring 3.

[0026] L-shaped channel 24 appears in an annular recess 29, the concave surface of which points toward the curved edge 21 and is defined between the shield 11 and the lip 12; the lip 12 is the first radially outermost lip of the annular washer 9 (i.e., the lip furthest from axis A) and extends obliquely relative to the flange 16 in a direction away from the sleeve portion 15, so as to cooperate with the flange 16, thus the lip 12 and the flange 16 define a second labyrinth seal.

[0027] The flange 16 may have a central right-angle bend 31 that defines an L-shape in a radial cross-section, the L-shape being located on opposite sides of an L-shape defined by an edge 21 that is preferably bent at a right angle; the bend 31 is disposed at an outlet within an annular recess 29 of a constant-width L-shaped channel 24 and extends axially over the concave surface of the annular recess 29 to form a drip guide designed to guide any external contaminants passing through the first labyrinth seal 22 into the annular recess 29 during use.

[0028] The flange 16 terminates on one side of the sleeve 15 with a second annular portion, which is obliquely disposed relative to the sleeve 15 and extends axially from a portion of the first annular portion or edge 21 folded at a right angle, thereby defining a cavity 33 with a truncated conical shape on the opposite side of the sleeve 15, which is filled with a water-repellent substance 34 during use.

[0029] The third annular portion 35 of the flange portion 16 is disposed between the second annular portion and the preferably right-angled intermediate bend 31, and is formed as a flat annular portion that is designed to contact the axial shoulder 36 of the rotating element 4 (defined by the flange end 5 in the example shown) during use, and is designed instead to serve as an assembly shoulder for fitting the shield 10 onto the radially outer cylindrical side surface 37 of the rotating element defined by the inner ring 4.

[0030] Basically, the flange 16 is shaped to extend annularly away from the sleeve 15 in both the axial and radial directions (optional for the specific example shown), and then continues perpendicularly relative to the sleeve 15, with an annular portion 35 leaving the sleeve 15 only in the radial direction. The flange 16 moves back toward the sleeve 15 again through the bend 31, and then the flange 16 moves only in the radial direction away from the sleeve 15, which is parallel to the annular portion 35. The flange 16 terminates in a right-angled bend edge 21, which extends parallel to the sleeve 15 and is in a position facing the sleeve 15.

[0031] The lip 13 is a second lip of the annular washer 9 that travels in the radial direction, and according to the invention, the lip 13 cooperates with the annular portion in a fluid-sealing manner by sliding contact. The annular portion defines a conical sealing surface 38 toward the lip 13 and the shield 11. The conicity of the conical sealing surface 38 points toward the shield 11, that is, the conical sealing surface 38 converges toward axis A on the side where the shield 11 is located.

[0032] exist Figure 1 In order to better understand, the lip 13 is not shown to scale, and in the undeformed construction, the lip 13 is partially shown in shaded form.

[0033] The sealing assembly 1 also includes an annular groove 39 disposed on the fixing element 3. The annular groove 39 is formed on the side surface 23 of the fixing element or outer ring 3 (which is generally cylindrical) adjacent to the right-angled bend edge 21 and is defined in the axial direction by a bend 40. The groove 39 becomes deeper along the bend 40 in the direction toward the rotating element 4 and the axis A, and the annular groove 39 is then sequentially defined by a straight section 41 that defines an inclined surface. The depth of the groove 39 decreases to zero along the inclined surface.

[0034] The annular groove 39 is formed such that the concave surface of the curved portion 40 points to the side that any external contaminants may reach during use, as schematically shown by arrow K; preferably, as Figure 1As indicated by the solid line, the concave surface of the curved portion 40 points towards the opposite side of the rotating element 4. However, the groove 39 can have different forms, particularly if the expected direction of arrival of the contaminants is different, the groove 39 can have, for example, […]. Figure 1 The different forms are shown by the dashed lines in the diagram.

[0035] The third lip 14 of the annular gasket 9 is a so-called grease stop lip, which extends obliquely toward the sleeve portion 15. Preferably, the lip 14 cooperates with the sleeve portion 15 to form a seal 43 without sliding contact. However, the grease stop lip 14 may also be designed to slide on the sleeve portion 15.

[0036] Sleeve portion 15 and sleeve portion 18 are respectively defined by cylindrical mating surfaces 44 and 45, which are formed on the rotating element 4 and the fixed element 3 during use. Sleeve portion 18 is lined with an elastomeric material. An appropriate amount of waterproofing material is applied to surface 44 along the second annular portion of flange portion 16 to increase the sealing effect.

[0037] Reference Figure 2 102 indicates a hub unit equipped with the sealing assembly 101 as described above, which is entirely similar to the sealing assembly 1 described above. Therefore, details similar to or identical to those already described will not be further explained, and for those details, please refer to... Figure 1 All the icon numbers. For easier explanation, Figure 2 It includes two details: one (upper) detail involves the upper part of the hub unit, and the other (lower) detail involves the lower part of the unit.

[0038] The hub unit 102 includes: an outer ring 103 that is stationary during use; an inner ring 104 that rotates about an axis A during use, the axis A being the axis of symmetry between the rings 103 and 104; and at least one row of rolling elements 6 located between the coaxial outer ring 103 and inner ring 104.

[0039] Specifically, the sealing assembly 101 includes a shield 11 and a shield 10. Shield 11 is stationary during use and has an annular gasket 209, while shield 10 rotates during use. Shields 11 and 10 are more or less identical to the shields of the sealing assembly 1. In this configuration, the flange 16 also terminates at an edge 21 that bends at a right angle, which, together with the retaining element 103, defines a first labyrinth seal 22. Regarding the upper portion (upper), the retaining element (i.e., the radial outer ring 103) is formed to have the same profile as previously described for the outer ring 3. In particular, the side surface 23 can be identified, as described above, comprising a cylindrical portion 26 and an annular groove 39. This external shape of the radial outer ring 103 essentially acts as a deflector, preventing contaminant elements from directly entering the bearing interior and thus deflecting the flow of contaminant elements toward the flange end 105 of the radial inner ring 104, which rotates during use.

[0040] According to the invention, regarding the lower portion (bottom) of the hub unit, an interruption of the annular shielding on the lower side of the hub unit is defined by the flattening 126 of the first cylindrical portion 26 (as seen in the upper portion), the interruption having a depth such that it almost eliminates all the annular grooves 39 in the side surface 23 of the stationary element 103 (as seen again in the upper portion). In this way, the width of the lower portion 122 of the labyrinth seal in the lower portion of the hub unit will be greater than the width of the upper portion 22 of the labyrinth seal in the upper portion of the hub unit, thereby facilitating the drainage of water, sludge, and common contaminants by gravity.

[0041] Reference Figure 3 The flat portion 126 can have different angular widths depending on the specific operating conditions of the hub unit 102. In particular, a trade-off must be considered between a) limiting the entry of contaminants and b) allowing the evacuation of contaminants. According to the first aspect, the angular interruption of the shield must have the minimum possible width, especially if the structure of the vehicle with the hub unit facilitates the entry of sludge and other contaminants not only from above but also from the side. According to the other aspect, alternatively, it is clear that a larger angular width of the interruption in the shield is beneficial for the evacuation of contaminants. Preferably, for operating conditions where low contaminant accumulation is envisioned and therefore a smaller evacuation capacity is required, the angular width can be approximately 45° (the order of 45°). Figure 3 a). Alternatively, under more demanding operating conditions, this angle width can be approximately 120° ( Figure 3 b) or even up to 180° ( Figure 3c), thus involving the entire bottom of the labyrinth seal and hub unit.

[0042] In this way, better emissions can be achieved in areas with less exposure to contaminant ingress, but this is actually useful for allowing sludge discharge via simple gravity. The overall design achieves a balanced approach to preventing contaminant ingress into the upper and sides of the hub unit, while improving emissions performance regarding the bottom side of the bearing. This maximizes the performance of the hub unit with its low-friction labyrinth seal assembly under all operating conditions.

[0043] It should be understood that the present invention is not limited to the embodiments described and shown, which are considered as examples of embodiments of low-friction sealing assemblies, and further modifications may be made to these embodiments with respect to the form and configuration of the components and the details of the structure and assembly.

Claims

1. A hub unit (102), comprising: A radial outer ring (103) remains stationary during use; a radial inner ring (104) rotates during use and has a flange end (105) opposite to the outer ring (103); at least one row of rolling elements (6) is located between the radial outer ring and the radial inner ring; and a sealing assembly (101) is located between the radial outer ring (103) and the radial inner ring (104), and the sealing assembly (101) cooperates with the radial outer ring (103) or the radial inner ring (104) to define a shield for at least one labyrinth seal (22, 122). The hub unit (102) is characterized in that the labyrinth seal does not have circumferential symmetry, but includes an upper part (22) and a lower part (122) relative to the axis of symmetry (A) of the hub unit, and is provided with an angular interruption of the shielding member formed on the lower part (122) of the labyrinth seal corresponding to the lower side of the hub unit (102), thereby increasing the outflow portion of the labyrinth seal from the labyrinth seal itself, which helps the gravity discharge of contaminants present in the sealing assembly (101); - The sealing assembly (101) includes: a first shield (11) that is stationary during use and has an annular gasket (9); and a second shield (10) that rotates during use and is provided with a flange (16) terminating at a right-angled bend edge (21); and - The radial outer ring (103) has a radial outer surface (23), and the right-angled curved edge (21) of the flange (16) extends axially toward the annular groove (39) formed on the radial outer surface (23) of the radial outer ring (103) between a first cylindrical portion (26) of the radial outer surface of the outer ring and a second cylindrical portion (42) adjacent to the first cylindrical portion (26), and the right-angled curved edge (21) has a diameter larger than the diameter of the first cylindrical portion (26), such that it defines the upper part (22) of the labyrinth seal with the radial outer ring (103). An angular interruption of the shielding member on the lower part (122) of the labyrinth seal is defined by the flat portion (126) of the first cylindrical portion (26), the interruption having a depth such that it almost eliminates all the annular grooves (39) of the radially outer surface (23) of the radial outer ring (103).

2. The hub unit (102) according to claim 1, characterized in that, The angular width of the flat portion (126) of the radial outer ring (103) is approximately 45°, 120°, or 180°.

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