Motor vehicle wheel centering method and centered wheel assembly

Abstract

The present invention relates to a wheel centering method and a centered wheel assembly for a motor vehicle obtained according to said method. It comprises the following steps: a structural element is provided comprising a hub (10) having a support portion (14) and a centering portion (16) having an external diameter d and extending projecting from said support portion (14); a wheel is provided comprising an aluminum rim (22) having an axial bore (24) of diameter D, so as to be able to adjust said rim (22) against said circular support portion (14), while said centering portion (16) extends through said bore (24). A steel ring (30) is further provided having an internal diameter Di between said bore diameter D and said external diameter d, Di < D; and said steel ring (30) is inserted inside said bore (24). Figure to be published with the abstract: Fig. 5

Description

Title of the invention: Method for centering a motor vehicle wheel and centered wheel assembly

[0001] The present invention relates to a method for centering a motor vehicle wheel and to a centered wheel assembly.

[0002] Usually, motor vehicles include hubs on which the wheels are installed by means of their rim.

[0003] Thus, the hub has a circular axial support part and a cylindrical centering part with a circular directrix curve, or hub nose, which projects from the center of the circular axial support part.

[0004] The wheels comprise a rim having an axial bore, so as to be able to adjust the rim against the circular axial support portion, while the centering portion extends through the bore to radially adjust the rim relative to said hub.

[0005] When the rim is made of steel, the axial bore may have a diameter substantially equivalent to the diameter of the cylindrical centering part, excluding functional clearance, so that this cylindrical central part can pass through the bore and play its role of radial guidance. This provides satisfactory centering, making it possible to avoid excessive eccentricity. Indeed, the eccentricity of the wheel relative to its axis of rotation leads to the appearance of an "unbalance", which tends to cause vibrations and increase the wear rate of the rotating elements.

[0006] When the rim is made of aluminum, although the axial bore can be made with more precision, it is important that the inner edge of the rim is relatively spaced from the cylindrical central part to avoid possible galvanic coupling.

[0007] Indeed, the cylindrical central part is made of steel, and therefore contains essentially iron, whose electrochemical potential is far from that of aluminum. Therefore, if the rim is in contact with the central part, in the presence of water, the aluminum tends to corrode. Also, such a galvanic bridge between steel and aluminum tends to operate a "galvanic" weld.

[0008] Also, a problem which arises and which the present invention aims to solve is to provide a method of centering a wheel having an aluminum rim, on a steel hub, without however causing the inconveniences of galvanic coupling.

[0009] For this purpose, and according to a first object, a method for centering a motor vehicle wheel is proposed comprising the following steps: a motor vehicle structural element is provided comprising a hub, said hub having a circular axial support part and a cylindrical centering part with a directing curve circular having an external diameter d and extending projecting in the center of said circular axial support portion; a wheel is provided comprising an aluminum rim having an axial bore of bore diameter D greater than said external diameter d, so as to be able to adjust said rim against said circular axial support portion, while said centering portion extends through said bore to radially adjust said rim relative to said hub. A steel ring is further provided having an internal diameter between said bore diameter D and said external diameter d, Di < D; and said steel ring is inserted inside said bore.

[0010] Thus, a characteristic of the invention lies in the implementation of a steel ring between the cylindrical centering part of the hub and the bore of the rim. Also, the steel ring is pre-installed and centered inside the bore. In this way, the centering of the wheel relative to the hub, in other words the radial guidance, is carried out by the relative position of the steel ring and the cylindrical centering part.

[0011] Obviously, the internal diameter of the ring is strictly less than the bore diameter D.

[0012] It is then understood that no galvanic coupling occurs between the steel ring and the cylindrical centering part that it surrounds.

[0013] For example, the steel ring has an internal diameter Di between said external diameter d and the sum of the bore diameter D and the external diameter d, divided by two.

[0014] According to a particularly advantageous characteristic of the invention, said ring has a substantially radial slot. The slot may have a relatively large width, for example a few millimeters, so as to be able to grip the ring and reduce its diameter, thus facilitating its insertion inside the bore of the rim. The ring is made of an elastically deformable steel so as to be able to return to its original shape after being gripped.

[0015] Preferably, said ring has an internal surface provided with a boss. In other words, the width of the internal circular support surface of the ring is reduced. In this way, the contact surface of the ring against the centering part is reduced, which makes it easier to mount and dismount the wheel.

[0016] In addition, said ring has a cylindrical external surface and two flanks opposite each other defining two circular edges, and, preferably, one of said edges is chamfered. In this way, the ring can be applied against the rim so that the chamfer comes to bear against the edges of the bore. Then, by applying an axial force to the ring, the chamfer then forms a ramp and allows the ring to be tightened thanks to its radial slot. Thus, the ring can be forcefully engaged inside the bore.

[0017] According to a particularly advantageous embodiment of the invention, a groove is hollowed out inside said bore to accommodate said ring. In this way, the ring is inserted inside the bore so as to keep it in a fixed position relative to the rim. It is easy to insert the ring inside the groove by gripping it to reduce its diameter and by forcing it axially inside the bore up to the groove where it resumes its original diameter.

[0018] According to another embodiment, a shoulder is provided inside said bore to form an axial support for said ring. In this way, the ring is locked in translation inside the bore against the shoulder.

[0019] Preferably, a half-moon shaped groove is machined in front of said shoulder. In this way, after having engaged the ring inside the bore and having brought it to bear against the shoulder, a toric stop ring is engaged inside the half-moon shaped groove to trap the ring inside the bore.

[0020] According to another object, a motor vehicle centered wheel assembly is provided. The assembly comprises: a motor vehicle structural element comprising a hub, said hub having a circular axial support portion and a cylindrical centering portion with a circular directrix curve having an external diameter d and extending projecting from the center of said circular axial support portion; a wheel comprising an aluminum rim having an axial bore of bore diameter D greater than said external diameter d, said rim being adjusted against said circular axial support portion, while said centering portion extends through said bore to radially adjust said rim relative to said hub; and, a steel ring having an internal diameter Di between said bore diameter D and said external diameter d, Di < D, and said steel ring is inserted inside said bore.

[0021] This gives a wheel with an aluminum rim, which is perfectly centered on its hub, and without the inconvenience of galvanic coupling.

[0022] Preferably, said ring has a substantially radial slot. Such a split ring has all the advantages described above.

[0023] Furthermore, said rim has a groove hollowed out inside said bore to accommodate said ring. The ring is thus perfectly maintained in translation in an axial direction. In this way, it remains in a fixed position during wheel changes.

[0024] Other features and advantages of the invention will emerge from reading the description given below of particular embodiments of the invention, given for informational but non-limiting purposes, with reference to the appended drawings in which:

[0025] [Fig.l] is a partial schematic view in axial section of an element of the assembly according to the invention;

[0026] [Fig.2] is a partial schematic view in axial section of another element of the assembly in accordance with the invention according to a first mode of implementation;

[0027] [Fig.3] is a partial schematic detail view of the object of [Fig.2];

[0028] [Fig.4] is a schematic view of another detail of the object of [Fig.2];

[0029] [Fig.5] is a partial schematic view in axial section of the objects of [Fig.l] and [Fig.2] combined;

[0030] [Fig.6] is a partial schematic view in axial section of the object of [Fig.4] according to another mode of implementation;

[0031] [Fig.7] is a partial schematic view in axial section of the combination of the object of [Fig.6] and the object of [Fig.3]; and,

[0032] [Fig.8] is a partial schematic view in axial section of the combination of the object of [Fig.6] and the object of [Fig.3] according to another mode of implementation.

[0033] [Fig.l] shows in axial section, a hub 10 located at the end of a wheel shaft 12 and having an axis of symmetry A. The hub 10 has a circular axial support part 14, or flange, and a cylindrical centering part with a circular base 16, extending in projection at the center of the circular axial support part 14. The circular support part 14 and the cylindrical centering part 16 are made of steel.

[0034] The cylindrical centering part with a circular base 16, also called the “hub nose”, allows the centering of the wheel as will be explained in more detail below. Also, its axis of symmetry corresponds precisely to the axis of symmetry A of the hub 10 and its external diameter d, defined by its external cylindrical surface 15, is precise. Here, for example, it is 60 mm.

[0035] Furthermore, [Fig.l] shows two threads 18, 20 opposite each other and made in a direction parallel to the axis of symmetry A of the hub, through the circular axial support part 14. The circular support part 14 has other threads not appearing in [Fig.l].

[0036] [Fig. 2] partially illustrates, in axial section, the central part of an aluminum rim 22 of a motor vehicle wheel. It has an axis of circular symmetry S and a bore 24 centered on the axis of circular symmetry S.

[0037] Also, the rim 22 has, in [Fig.2], two diametrically opposed through-holes 26, 28 adapted to receive screwing elements as will be explained below. The rim has other holes, corresponding to said other threads, to be able to secure it perfectly to the circular support part 14.

[0038] The bore 24 has a diameter D, with a value of 68 mm in the example presented here and within a tolerance interval of 0.04 mm, corresponding to a machining tolerance and not to a stamping tolerance.

[0039] Furthermore, the rim 22, made of aluminum, is provided with a steel ring 30 inserted in the bore 24 as will be explained in more detail below with reference to [Fig.3].

[0040] [Fig. 3] shows in more detail the center of the rim 22, and more precisely the bore 24, freed from the steel ring 30. The bore 24 has a bearing, that is to say a relatively significant depth, greater than 5 mm, for example 8 mm. Also, a groove 32 is made inside the bore 24.

[0041] The groove 32 has a width, for example close to 5 mm and a depth of the order of 1 mm. It is of rectangular section. In addition, the groove 32 defines a groove rim 35.

[0042] Furthermore, the groove edge 35 extends towards the outside of the rim 22 by a chamfered entrance 29, the use of which will be specified in the remainder of the description.

[0043] Thus, the steel ring 30 as illustrated in perspective in [Fig.4] will be able to be housed inside the bore 24 in the groove 32 as will be explained below.

[0044] The steel ring 30 shown in [Fig.4] is of cross section, in other words of radial, rectangular section. It has an external cylindrical surface 31 defining an external diameter De and an opposite internal cylindrical surface 33, defining an internal diameter Di. In addition, the ring 30 has two opposite flanks 37, 39.

[0045] The steel ring 30 is preferably obtained from a cylindrical tube with a circular base obtained by fine turning, then cut to the required width.

[0046] Furthermore, it is split, and its slot 34 is more or less wide. In this case, it corresponds to a truncation defining two free ends facing each other 36, 38.

[0047] The ring 30 here has a width L of 5 mm and a radial thickness e of 4 mm. The tolerances on the thickness are 0.01 mm, i.e. the tolerance interval for the deviation of the inner and outer radii.

[0048] Also, the internal diameter Di is 60 mm in the example presented here and the external diameter De is 68 mm. The internal diameter Di is well between the diameter D of the bore 24 and the external diameter d of the centering part 16.

[0049] The internal diameter Di of the ring 30 is also between 60 mm and 64 mm, corresponding to the half-sum of the diameter D of the bore 24 and the external diameter d of the centering part 16.

[0050] Furthermore, the coaxiality defect of the inner diameters Di and outer diameters De is also 0.01 mm.

[0051] According to another example of implementation, the ring has a thickness of 3 mm and its internal diameter Di is 62 mm. The bore 24 retains the dimensions given above.

[0052] Thanks to the slot 34, the steel ring 30 is elastically deformable so that it can be gripped, while these two facing free ends 36, 38 move closer to each other. Its average diameter is then reduced and it can be inserted easily inside the bore 24 by crossing the rim 35 to be able to be released at the right of the groove 32 where it resumes its original shape.

[0053] [Fig.2] illustrates the ring 30 thus adjusted inside the groove 32. It is then held in a fixed position in the axial direction.

[0054] In this way, the rim 22 and more broadly the wheel can be adjusted on the hub 10, as illustrated in [Fig. 5]. The rim 22 is adjusted so as to engage the cylindrical centering part 16 through the bore 24. The cylindrical centering part 16 then makes it possible to guide the rim 22 radially by means of the steel ring 30 which is driven axially in sliding on the cylindrical surface 15 of the cylindrical centering part 16.

[0055] The rim 22 is then applied against the circular application part 14. And after aligning the orifices 26, 28 with the threads 18, 20 respectively, fixing screws 40, 42 are engaged through the orifices 26, 28 to screw them into the threads 18, 20.

[0056] This then results, taking into account the aforementioned tolerances, in an average eccentricity of 0.0 35 mm and a maximum eccentricity of 0.0 65 mm.

[0057] The steel ring 30 which naturally comes into contact with the cylindrical centering part 16, itself made of steel, does not induce any galvanic coupling since by nature, these two elements have the same electrochemical potential.

[0058] We will now refer to [Fig.6], which shows a cross-section of a steel ring 30' according to another embodiment. The elements of the object of [Fig.6] having the same functions as those of the object of [Fig.4] will have the same reference assigned a sign: "'".

[0059] Thus, the steel ring 30' has two opposite flanks 37', 39' and an external cylindrical surface 31' opposite an internal cylindrical surface 33'.

[0060] It will be observed, on the one hand, that the edge defined by the external cylindrical surface 31' and the flank 39' has been cut down to form a chamfer 46, and on the other hand, that the bearing surface of the internal cylindrical surface 33' has been reduced by the formation of a circular boss 48 in the center of the internal cylindrical surface 33'.

[0061] Thus, the steel ring 30' is applied against the rim 22 in such a way that the chamfer 46 comes to bear precisely against the chamfered entry 29 of the rim 22. And by forcing the ring 30' against the rim 22, the chamfered entry 29 then forms a ramp so that the ring 30' contracts and sees its diameter reduce as the ring 30' penetrates inside the bore 24, while the chamfer 46 is driven in friction against the chamfered entry 29.

[0062] When the ring 30' reaches the groove 32', then the ring 30' relaxes inside and returns to its original diameter, as illustrated in [Fig.7].

[0063] Of course, such an implementation must be carried out before mounting the wheel on the hub 10.

[0064] Also, thanks to the boss 48, the contact surface of the ring 30' with the circular axial support part 14 of the hub 10 is smaller. This characteristic makes it easier to disassemble and reassemble the wheel. And it does not in any way harm the centering qualities of the rim.

[0065] Reference will now be made to [Fig.8] illustrating another method of implementing a 22' rim, associated with the 30' steel ring as shown in [Fig.6].

[0066] Thus, the bore no longer has a groove, but simply a shoulder 50, against which the flank 39' of the ring 30' comes to bear axially.

[0067] In other words, according to this other embodiment, compared to the first, the rim 35 as illustrated in [Fig. 3] has disappeared. Thus, the steel ring 30' could be force-fitted into the bore 24' without significant contraction, until it abuts against the shoulder 50.

[0068] Furthermore, a half-moon groove 52 is provided at the entrance to the bore 24' in order to be able to carry an elastically deformable ring 54 there. This elastically deformable ring 54 is easily force-fitted inside the half-moon groove 52 and it makes it possible to maintain the ring 30' in a fixed position inside the bore 24'.

Claims

Claims

1. A method for centering a motor vehicle wheel comprising the following steps: - a motor vehicle structural element is provided comprising a hub (10), said hub having a circular axial support portion (14) and a cylindrical centering portion (16) made of steel, with a circular directrix curve having an external diameter d and extending projecting from the center of said circular axial support portion (14); - a wheel is provided comprising an aluminum rim (22) having an axial bore (24) of bore diameter D greater than said external diameter d, so as to be able to adjust said rim (22) against said circular axial support portion (14), while said centering portion (16) extends through said bore (24) to radially adjust said rim (22) relative to said hub (10);characterized in that a steel ring (30) is further provided having a substantially radial slot and an internal diameter Di between said bore diameter D and said external diameter d, Di < D; and in that said steel ring (30) is inserted inside said bore (24) between the cylindrical centering portion of the hub and the bore of the rim, whereby no galvanic coupling occurs between the steel ring (30) and the cylindrical centering portion (16) which it surrounds.;

2. Centering method according to claim 1, characterized in that said ring (30) has an internal surface provided with a boss (48).

3. Centering method according to claim 1 or 2, characterized in that said ring (30') has a cylindrical external surface (31') and two opposite flanks (37', 39') defining two circular edges, and in that one of said edges is chamfered.

4. Centering method according to any one of claims 1 to 3, characterized in that a groove (32) is hollowed out inside said bore (24) to accommodate said ring (30).

5. Centering method according to any one of claims 1 to 3, characterized in that a shoulder (50) is provided inside said bore (24) to form an axial support for said ring (30').

6. Centering method according to claim 5, characterized in that a half-moon groove (52) is machined in front of said shoulder (50).

7. A motor vehicle centered wheel assembly comprising: - a motor vehicle structural element comprising a hub (10), said hub having a circular axial support portion (14) and a cylindrical steel centering portion, with a circular directrix curve (16) having an external diameter d and extending projecting from the center of said circular axial support portion (14); - a wheel comprising an aluminum rim (22) having an axial bore (24) of bore diameter D greater than said external diameter d, said rim (22) being adjusted against said circular axial support portion (14), while said centering portion (16) extends through said bore (24) to radially adjust said rim relative to said hub (10);characterized in that it further comprises a steel ring (30) having an internal diameter Di between said bore diameter D and said external diameter d, Di < D, and in that said steel ring (30) has a substantially radial slot (34) for being inserted inside said bore (24) between the cylindrical centering part of the hub and the bore of the rim, whereby no galvanic coupling occurs between the steel ring (30) and the cylindrical centering part (16) which it surrounds.;

8. Assembly according to claim 7, characterized in that said rim (22) has a groove (32) hollowed out inside said bore (24) to accommodate said ring (30).