Radial inner ring element of hub provided with front teeth for transmitting torque

Abstract

The annular element (10) of the hub (1) is provided with front teeth (8) for transmitting torque; a plurality of teeth (16) extending radially between a first diameter (dext) and a second diameter (dmin) of the anterior tooth (8) and having a ridge (20); the first end (18) of the tooth (16) extends to a third diameter (dmaxround) of the anterior tooth (8) at which the tooth (16) has a maximum height; the second end (19) of the tooth (16) extends to a fourth diameter (dminround) of the anterior tooth (8) at which the tooth (16) has a minimum height; the ridge (20) has a stretch (23) at which the teeth (16) have a straight radial profile and a rounded ridge (20); a ratio between the third diameter and the first diameter is greater than 0.9.

Description

Technical Field

[0001] The present invention relates to a radially inner annular element of a wheel hub, in particular consisting of the inner ring (or part of the inner ring) of a rolling bearing forming the wheel hub or forming part of the wheel hub, the radially inner annular element being provided with front toothing forming side face splines for transmitting torque, in particular between the radially inner annular element of the wheel hub and a constant velocity joint of a vehicle transmission.

[0002] In particular, the present invention applies to a wheel hub in which the inner ring of a rolling bearing forms a stub axle, the wheel hub having a first flange end and a second end opposite the first end, the wheel hub including an upset collar designed to receive, by pressure and the resulting plastic deformation, the front teeth or side splines required for mechanical connection with a constant velocity joint forming part of the vehicle's driveline and for receiving the motion transmission from the constant velocity joint. Background Art

[0003] In a wheel hub of the aforementioned type, the front teeth are intended to couple the inner ring of the hub (i.e., the rolling bearing) with corresponding front teeth of the outer ring of a constant velocity joint in an abutment manner, thereby ensuring torque transmission from the constant velocity joint to the inner ring of the hub, which carries the vehicle's wheel via its flanged end. This coupling is described in US Pat. No. 4,893,960 A.

[0004] In this type of coupling, the increasingly greater amount of transmittable torque required in modern applications is primarily related to the radial and axial dimensions of the front teeth, since the width of the lateral surfaces of the flanks of the teeth that can transmit torque depends on these dimensions. Unfortunately, in the prior art, in order to increase these dimensions and, therefore, the transmittable torque, it was necessary to increase the radial outer diameter of the teeth (and, possibly, also the radial inner diameter of the teeth), and, consequently, to increase the radial outer diameter of the radially inner annular element of the hub that carries the front teeth, which results in an undesirable increase in the size and weight of the hub.

[0005] This problem is further exacerbated by the fact that the aforementioned front teeth (flank splines) are usually obtained by plastic deformation of a first annular portion of the inner ring of the rolling bearing (this first portion forming the stub axle of the hub) and of its collar, which is upset against a small inner ring (SIR) which is driven onto the stub axle of the hub and usually forms the second annular portion of the inner ring of the rolling bearing.

[0006] In fact, on the one hand, this configuration requires the inner ring and the upset collar to be thick enough to withstand the mechanical working stresses, thereby imposing dimensional limitations on the maximum permissible radial and axial dimensions of the front teeth. On the other hand, due to the non-optimized dimensions of the front teeth of the inner annular element of the hub and / or defects in the shape of the teeth, incorrect coupling between the front teeth of the inner annular element of the hub and the teeth of the constant velocity joint may occur during use, which may be related not only to the method used to form the teeth by plastic deformation, but also to the failure to optimize the dimensions of the teeth and / or the upset collar due to the aforementioned dimensional limitations. Summary of the Invention

[0007] The present invention therefore aims to provide a radially inner annular element for a wheel hub, in particular, the radially inner annular element being constituted by the inner ring (or a part of the inner ring) of a rolling bearing of the wheel hub, the radially inner annular element being provided with front toothing for transmitting torque, the radially inner annular element being free from the disadvantages of the prior art and in particular enabling the vehicle wheel hub to be manufactured with a relatively high transmittable torque while being smaller and lighter.

[0008] The present invention also aims to provide a driven wheel hub for a vehicle, i.e. a hub intended to receive a driving wheel of a vehicle, which driven wheel hub is smaller and lighter and has a greater maximum transmittable torque than hubs of the prior art for the same size.

[0009] The invention also aims to ensure a correctly "soft" coupling between the teeth of the wheel hub and the teeth of the constant velocity joint of the vehicle's transmission, when in use.

[0010] The invention therefore provides a radially inner annular element of a hub and an associated driven hub as defined in the appended claims, in particular consisting of at least a portion of an inner ring of a rolling bearing, the radially inner annular element being provided with front teeth for transmitting torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other features and advantages of the present invention are more clearly set forth in the following description of non-limiting embodiments of the invention provided with reference to the figures of the accompanying drawings, in which:

[0012] - Figure 1 is a schematic illustration of an elevational longitudinal section of a driven hub made in accordance with the invention, the driven hub being designed to be coupled, in use, to a constant velocity joint of a vehicle transmission via a torque transmission, both the vehicle transmission and the constant velocity joint being known and shown only schematically as a dashed block for simplicity;

[0013] - Figure 2 yes Figure 1A schematic enlarged view of a detail of a driven wheel hub of the vehicle in FIG, also in elevational longitudinal section;

[0014] - Figure 3 is a schematic diagram of a vertical longitudinal section of a second possible embodiment of a driven hub made according to the present invention;

[0015] - Figure 4 yes Figure 3 A schematic enlarged elevational longitudinal section of a detail of a driven wheel hub of a vehicle;

[0016] - Figure 5 Also made according to the present invention and formed Figure 3 A schematic diagram of an elevational longitudinal section of an end portion of a radially inner annular element of a portion of a wheel hub, also illustrating some key design measurements of the front teeth of the radially inner annular element for transmitting torque;

[0017] - Figure 6 is a purely graphic, schematic, perspective three-quarter front view of a portion of a front toothing for transmitting torque of a wheel hub made according to the invention; and

[0018] - Figure 7 yes Figure 6 Purely graphic view of the circumferential profile of the front teeth in . DETAILED DESCRIPTION

[0019] exist Figures 1 to 7 In the figure, reference numeral 1( Figure 1 and Figure 2 ) or 1b( Figure 3 and Figure 4 ) is used as a whole to represent the driven wheel hub of a vehicle made according to the present invention, as described in detail below.

[0020] Hub 1( Figure 1 ) is designed to be connected in use from a vehicle transmission 2 (known and Figure 1 The constant velocity joint 3 receives the driving torque and is known per se, forming part of the vehicle transmission 2 and is also only schematically shown as a dashed block for simplicity.

[0021] Hub 1 b is a possible variation of hub 1 and, except for the details described below, is substantially identical to hub 1. Therefore, except for the details mentioned above and described below, the description of hub 1 will also apply to hub 1 b.

[0022] The hub 1 comprises an outer ring 4 and an inner ring 6 , the outer ring 4 being intended, in use, to be fastened to a vehicle suspension upright (not shown) in a known manner, for example by means of a radially outer flange 5 .

[0023] The outer ring 4 and the inner ring 6 are connected together in a relatively rotatable manner by means of two rows of rolling elements 7 (e.g. balls), which are radially inserted between the rings 4 and 6 and engage a pair of suitable annular raceways formed on the rings 4 and 6, which are known and therefore not described in detail.

[0024] In use, the inner ring 6 can be operatively associated with the constant velocity joint 3 in a known manner by means of front teeth 8 preferably obtained on an annular collar 9 using a plastic deformation process (known and therefore not described).

[0025] In the non-limiting example shown, the inner ring 6 comprises a radially inner annular element 10 of the hub 1 and a small inner ring (SIR) 11 driven radially onto the outside of a front axial end 12 of the annular element 10 .

[0026] Therefore, the radially inner annular element 10 of the hub 1 constitutes the hub rolling bearing 13 ( Figure 1 and Figure 3 ) at least a portion of the inner ring 6.

[0027] In the non-limiting example embodiment shown, the rolling bearing 13 also constitutes the entire hub 1 itself, which is designed as a hub unit (of a completely known type) in which the outer ring 4 is provided with a radial flange 5, while the annular element 10 is provided with a second flange 15 at its axial end 14 opposite the front axial end 12, the second flange 15 being designed to receive a vehicle wheel (known and not shown for the sake of simplicity).

[0028] However, the radially inner annular element 10 is always spindle-shaped, even if (in a possible variant, not shown for the sake of simplicity, as this is obvious to a person skilled in the art) the radially inner annular element 10 is not part of a rolling bearing 13, in which case the small inner ring 11 (or 11b) will not be present and the inner ring 6 of the rolling bearing 13 will consist of a one-piece annular component coupled to two rows of rolling elements 7 and assembled only onto the radially outer lateral surface of the annular element 10, in which case the annular element 10 still has two opposite front ends 12 and 14, the end 14 being provided with a flange 15 and the end 12 being provided with an annular collar 9.

[0029] In the non-limiting example embodiment shown, the radially inner annular element 10 is part of the inner ring of a rolling bearing 13 and the annular collar 9 is obtained by upsetting a portion of the front end 12 against the small inner ring 11 (or 11b), thereby axially locking the small inner ring 11 (or 11b) to the radially inner annular spindle element 10 of the hub 1 and forming part of the inner ring 6.

[0030] The front teeth 8 are in any case always carried by / formed on an annular collar 9, which is carried / formed on the front axial end 12 and which is mounted radially on the outside of the annular element 10 by being upset / folded by plastic deformation against the small inner ring 11 / 11b or (in the aforementioned variant, not shown) against the entire inner ring 6 of the rolling bearing 13.

[0031] Furthermore, as mentioned above, the front teeth 8 are designed to couple with the mating flank splines / front teeth of the constant velocity joint 3 in use to transmit torque between the constant velocity joint 3 and the radially inner annular element 10 .

[0032] The front teeth 8 for transmitting torque formed on the first axial front end 12 of the ring element 10 (in this case formed on the collar 9 of the ring element 10) include a plurality of radial teeth 16 arranged around the symmetry axis A ( Figure 1 、 Figure 3 and Figure 5 ) are arranged in a row and extend radially between the following ( Figure 5 and Figure 6 ):

[0033] a first diameter d_ext of the front teeth 8 defined by the respective first radially outer ends 18 of the teeth 16 , and

[0034] A second diameter d_min of the front teeth 8 is defined by the respective second radially inner ends 19 of the teeth 16 .

[0035] Furthermore, the teeth 16 are delimited axially on the side opposite to the side facing the front end 12 of the annular element 10 or on the side opposite to the end 14 by respective ridges 20 ( Figure 5 ).

[0036] Reference Figure 5 , the ridge 20 of each tooth 16 comprises, in a plane radial to the axis A:

[0037] a radially outer first radial stretch 21 delimiting the first end 18 of the tooth 16 and having a first curvilinear profile in radial section; the radial stretch 21 extends radially inwardly to a third diameter d_max_round of the front tooth 8, at which the tooth 16 has a maximum height measured in the axial direction (i.e. parallel to the axis A);

[0038] a radially inner second radial stretch 22 delimiting the second end 19 of the tooth 16 and having a second curvilinear profile in radial section; the radial stretch 22 extends radially outwards to a fourth diameter d_min_round of the front tooth 8 at which the tooth 16 has a minimum height measured in the axial direction (i.e. parallel to the axis A);

[0039] The third radially stretched portion 23 is defined between the first radially stretched portion 21 and the second radially stretched portion 22 and connects the first end 18 and the second end 19 of the tooth 16 to each other.

[0040] According to one aspect of the invention, in the third radial stretch 23, the ridges 20 of the teeth 16 all have a substantially straight profile of length L, as seen in radial section. Figure 5 Clearly shown in.

[0041] Furthermore, an important aspect of the present invention is that, in combination with the above features, the first stretched portion 18 of the ridge 20 of the tooth 16 is designed such that the ratio between the third diameter and the first diameter of the front tooth 8 is greater than 0.9, i.e. such that the following is true:

[0042] [1]d_max_round / d_ext>0.9.

[0043] Furthermore, according to another non-minor aspect of the invention, in a plane perpendicular to and transverse to the axis of symmetry A, in this case consisting of Figure 7 The plane of the page in FIG. 2 shows that the spine 20 of the tooth 16 is completely rounded (i.e., substantially free of any flat portion) throughout the third stretch 23 and preferably forms a pair of substantially flat opposing flanks 24 ( Figure 7 ) are connected together by arcs, and the flanks 24 are arranged obliquely to converge radially with each other outwardly and toward the corresponding ridge 20.

[0044] The ridges 20 of the teeth 16 are arranged perpendicularly and transversely to the axis of symmetry A (in this case perpendicularly to the Figure 5A plane β that is in the page plane in the middle (i.e., the center line) and passes through the midpoint of the profile of the second radial stretch portion 22 of the ridge 20 forms a predetermined first angle α_top. According to one aspect of the present invention, the first angle α_top should be between 4 degrees and 10 degrees.

[0045] Furthermore, the front teeth 8 comprise a plurality of radial channel-shaped recesses 25 ( Figure 7 ), the recess 25 is located on the side (flank) of each tooth 16 to separate each tooth from the other teeth 16, and is configured to form a second predetermined angle α_valley with a plane β that is perpendicular to and transverse to the axis of symmetry A and passes through the midpoint of the profile of the second radial stretch portion 22 of the ridge 20. According to one aspect of the present invention, the second predetermined angle α_valley should also be between 4 degrees and 10 degrees.

[0046] Preferably, the profile of the stretching portion 22 is designed such that the second predetermined angle α_valley is greater than the first predetermined angle α_top.

[0047] The front tooth 8 has a design diameter d_design between said first diameter d_ext and said fourth diameter d_min_round of the tooth 8, as shown Figure 5 shown.

[0048] According to another aspect of the present invention, the ratio between the aforementioned second diameter d_min of the front teeth 8 and the design diameter d_design of the front teeth 8 should be less than 0.65, that is, the following should be true:

[0049] [2]d_min / d_design<0.65.

[0050] Similarly, according to another aspect of the present invention, the ratio between the aforementioned fourth diameter d_min_round of the front teeth 8 and the design diameter d_design of the front teeth should be less than 0.7; that is, the following should be true:

[0051] [3]d_min_round / d_design<0.7.

[0052] The design diameter d_design is known a priori, since it depends on the torque range to be transmitted. According to the preferred embodiment shown, it can be assumed that d_design is substantially equal to the difference between the aforementioned first diameter d_ext and the length L of the third stretch 23 of the ridge 20 of the tooth 16. However, the length L should be measured parallel to the straight profile of the third stretch 23 of the ridge 20 of the tooth 16, rather than perpendicular to the axis A.

[0053] Now refer to Figure 1 and Figure 2As already mentioned, the radially inner annular element 10 of the hub 1 is preferably a spindle-shaped stretch or portion of the inner ring 6 of the rolling bearing 13, the inner ring 6 of the rolling bearing 13 comprising a first annular raceway for the rolling elements 7 and a small inner ring 11 comprising a second annular raceway for the rolling elements 7 being driven on the inner ring 6.

[0054] The first front end 12 of the annular element 10 is constituted by / comprises an annular collar 9 which is upset against the small inner ring 11 so as to lock it and which is provided with front teeth 8 which are preferably formed by plastic deformation of the annular collar 9 during upset.

[0055] According to another non-minor aspect of the invention, the first end 27 of the small inner ring 11 faces in the same manner as the first end 12 of the annular element 10 and includes a flat front face 28 and an annular shallow recess 29 formed radially inside the flat front face 28 of the small inner ring 11.

[0056] In conjunction with this feature, the annular collar 9 is designed to be only partially housed within the annular recess 29 , radially engaging on the inside of the annular recess 29 with radial play and protruding axially from the annular recess 29 over at least all of the greater height of the teeth 16 .

[0057] This further reduces the axial dimension of the hub 1 on the one hand, and promotes the meshing of the front teeth 8 with the teeth of the constant velocity joint 3 on the other hand.

[0058] The form of the tooth 8 described and its dimensions based on key parameters determined experimentally by the applicant's technicians, torque transmission and the radial extension of the tooth 16 and the extension of the surface of the side 24 of the tooth 16 are maximized compared to similar conventionally formed teeth, without increasing the axial and radial dimensions of the tooth 8.

[0059] According to the invention, the correct engagement of the teeth 8 with the teeth of the constant velocity joint 3 is improved on the one hand by the fact that the radial extension L of the stretched portion 23 of the tooth 16 is designed to be large and completely rounded, and is also maximized by:

[0060] a) Reduce the diameter d_min_round where the top of the tooth 16 is completely rounded: d_min_round / d_design<0.70;

[0061] b) Increase the ratio between the maximum diameter where the teeth are rounded and the maximum outer diameter of the front teeth 8: ρ = d_max_round / d_ext > 0.90.

[0062] at last, Figure 3 and Figure 4 Variant 1b in Figure 1 and Figure 2 The embodiment is the same as that in FIG. 1 , except that the small inner ring 11 is replaced by a small inner ring 11b of a slightly different shape, which is the same as that already described for FIG. Figure 1 and Figure 2 Details similar or identical to those described in the embodiments herein are denoted by the same reference numerals.

[0063] In particular, the small inner ring 11b also includes an end 27 defined by a flat front face 28, but instead of the shallow recess 29 (which is absent in this variant), the small inner ring 11b has a stepped annular groove 30 formed radially outside the end 27. A known sealing assembly 31 is inserted between the outer ring 4 and the small inner ring 11b, and the annular groove 30 is used to precisely accommodate a speed detector (known and not shown for simplicity) at the front tooth 8 for transmitting torque when in use, thereby obtaining an improved signal.

[0064] All objects of the invention are thus achieved.

Claims

1. A radially inner annular element (10) of a wheel hub (1), said annular element (10) presenting an axis of symmetry (A) and provided with front teeth (8) for transmitting torque at a first axial front end (12) of said annular element (10), said front teeth (8) comprising a plurality of teeth (16), said plurality of teeth (16) being arranged in a row about said axis of symmetry (A) and extending radially between a first diameter (d_ext) of said front teeth (8) and a second diameter (d_min) of said front teeth (8), said first diameter (d_ext) being defined by respective first radially outer ends (18) of said teeth (16) and said second diameter (d_min) being defined by respective second radially inner ends (19) of said teeth; wherein The teeth (16) are axially defined by respective ridges (20), said ridges (20) comprising: a first radially outer stretch (21) delimiting the first end (18) of the tooth and presenting, in radial section, a first curvilinear profile, extending radially inwards to a third diameter (d_max_round) of the front tooth (8) at which the tooth (16) reaches its maximum height measured in the axial direction; a radially inner second radial stretch (22) delimiting the second end (19) of the tooth (16) and presenting a second curved profile in radial section, extending radially outwards to a fourth diameter (d_min_round) of the front tooth (8) at which the tooth (16) reaches a minimum height measured in the axial direction; and - a third radial stretch (23) defined between the first radial stretch (21) and the second radial stretch (22) and connecting the first end (18) and the second end (19) of the tooth to each other; characterized in that (a) the ridge (20) of the tooth has a substantially straight profile in radial cross-section and along the third stretch (23); (b) The first stretched portion (21) of the ridge (20) of the tooth (16) is configured such that a ratio of the third diameter to the first diameter of the front tooth (8) is greater than 0.

9.

2. The ring element according to claim 1, characterized in that In a plane perpendicular to and transverse to the axis of symmetry (A), the ridge (20) of the tooth (16) is completely rounded along the third stretch portion (23), preferably, the ridge (20) of the tooth (16) is formed along the third stretch portion (23) as an arc connecting a pair of substantially flat opposite side surfaces (24) of each tooth (16), and the pair of substantially flat opposite side surfaces (24) are configured obliquely so as to converge radially with each other outward and toward the ridge (20).

3. The ring element according to claim 1 or 2, characterized in that The ridge (20) of the tooth is configured to form a first predetermined angle (α_top) with a plane perpendicular to and transverse to the axis of symmetry (A) and passing through the midpoint of the profile of the second radial stretch (22) of the ridge (20) with a magnitude between 4 and 10 degrees.

4. Annular element according to any one of the preceding claims, characterized in that The front teeth (8) include a plurality of radial channel-shaped recesses (25) located on the side of each tooth (16) to separate the tooth (16) from the other teeth and configured to form a second predetermined angle (α_valley) with an amplitude between 4 and 10 degrees with a plane perpendicular to and transverse to the axis of symmetry (A) and passing through the midpoint of the profile of the second radial stretch (22) of the ridge (20).

5. The ring element according to claim 3 and 4, characterized in that The second preset angle (α_valley) is greater than the first preset angle (α_top).

6. Annular element according to any one of the preceding claims, characterized in that The front teeth (8) have a design diameter (d_design) value between the values ​​of the first diameter (d_ext) and the fourth diameter (d_min_round); and a ratio of the second diameter (d_min) to the design diameter (d_design) is less than 0.

65.

7. The ring element according to claim 6, characterized in that A ratio of the fourth diameter (d_min_round) to the design diameter (d_design) is less than 0.

7.

8. Annular element according to claims 6 and 7, characterized in that Said design diameter depends on the category of the torque interval to be transmitted and is preferably substantially equal to the difference between said first diameter (d_ext) and the length (L) of the third stretch (23) of the ridge (20) of the tooth measured parallel to the straight profile of the third stretch (23) of the ridge of the tooth.

9. Annular element (10) according to any one of the preceding claims, characterized in that The annular element (10) is part of an inner ring (6) of a rolling bearing (13), the inner ring (6) comprising a first annular raceway for a rolling element (7), and a small inner ring (11) comprising a second annular raceway for a rolling element (7) is mounted on the inner ring (6); a first front end (12) of the annular element (10) comprises an annular collar (9), the annular collar (9) being upset against the small inner ring (11) to lock the small inner ring (11), and being provided with front teeth (8), the front teeth (8) preferably being passed through the annular collar (9); the first end (27) of the small inner ring (11) faces the same side as the first end (12) of the annular element (10), and the first end (27) includes a flat front face (28) and an annular shallow recess (29) obtained radially on the inner side of the flat front face (28) of the insert ring (11); the annular collar (9) is partially accommodated in the annular shallow recess (29), is located radially on the inner side of the annular shallow recess (29), and protrudes axially to the outer side of the annular shallow recess (29).

10. A driven wheel hub (1) capable of being inserted into a vehicle transmission (2) to be coupled to a constant velocity joint (3) having side splines by torque transmission; wherein The wheel hub (1) comprises a rolling bearing (13), the rolling bearing (13) comprising an outer ring (6), a plurality of rolling elements (7) and an inner ring (6) carried by an annular element (10) according to any one of the preceding claims, or comprising an annular element (10) according to any one of the preceding claims and a small inner ring (11; 11b) mounted on the annular element (10), the outer ring (6) preferably being provided with a first flange (5) on the radial outside; the annular element (10) being spindle-shaped and having a second flange (15) at a second front end (14) of the annular element (10) opposite to the first front end (12), the second flange (15) being configured to receive a vehicle wheel; the first front end (12) presents an annular collar (9) supporting the front teeth (8), the annular collar (9) being configured to be splined to the side of the constant velocity joint (3) in use.

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