Adjustable center distance brake drum

Abstract

A brake drum (1) comprising a skirt, generally of revolution about a principal axis (A1) of rotation, and a discoidal portion extending generally perpendicularly to the axis of rotation, the discoidal portion comprising a plurality of threaded holes (2) adapted to receive screws for fixing a vehicle wheel, characterized in that each threaded hole is made in an eccentric part (3), which is received directly or indirectly via an intermediate eccentric support (4) in a bored bearing (14) formed in the discoidal portion of the drum, the eccentric parts being configured to be pivoted so as to vary the center distance. Figure from the abstract: Fig. 3

Description

Title of the invention: Adjustable center distance brake drum

[0001] This disclosure relates generally to the field of brake drums, and to the problem of fixing vehicle wheels to brake drums.

[0002] Vehicle wheels are fixed to brake drums by means of screws which are screwed into tapped holes provided in the brake drum.

[0003] Depending on the different possible configurations, 4 fixing screws, or 5 fixing screws, or even 3 fixing screws may be provided.

[0004] Furthermore, the number of screws is not the only variable, as the distance of the tapped holes from the wheel's axis of rotation differs from one technical platform to another. In practice, this is also referred to as the center-to-center distance of the holes, which corresponds to the diameter, namely twice the radius corresponding to the distance mentioned above.

[0005] The present invention relates more specifically to the optimization of the solution with respect to the technical diversity of the distance of the tapped holes from the axis. It should be noted that the wheel axle coincides with the drum axle.

[0006] The known solutions involve a drum variant for each of the distance values ​​of the tapped holes relative to the wheel axle.

[0007] In this context, the inventors sought to propose a solution to reduce technical diversity and to be able to mount wheels with different center distances on a drum with adaptable center distance.

[0008] To achieve this objective, the invention proposes a brake drum, comprising a skirt generally of revolution around a main axis of rotation, and a discoid portion generally extending perpendicularly to the axis of rotation, the discoid portion comprising a plurality of threaded holes suitable for receiving screws for fixing a vehicle wheel, characterized in that each threaded hole is made in an eccentric part, the eccentric part being received directly or indirectly in a bored bearing provided in the discoid portion, and configured to be pivoted in the bored bearing around a local axis parallel to the main axis.

[0009] Thanks to these arrangements, by means of a rotation of the eccentric part, it is possible to adjust the distance which separates the axis of the threaded hole from the main axis of the drum.

[0010] Thanks to the fact that, on the eccentric part, the axis of the threaded hole is offset relative to the axis of the cylindrical bearing received in the bored bearing, it is obtained that if the eccentric part is rotated, the axis of the threaded hole moves closer to or further from the axis of the wheel. Thanks to this trick, a given type of drum can accept wheels with different screw center distances.

[0011] It is noted that it is of course preferable that the rotations of all the eccentric parts be consistent.

[0012] It is noted that the so-called inner side of the drum is the one where the brake mechanism is arranged, the so-called outer side of the drum is the one on which the wheel rim rests.

[0013] The number of threaded holes can be 4 as in the main example illustrated, but of course the number of threaded holes can be 5 or can be 3.

[0014] According to an advantageous option, an eccentric intermediate support is advantageously provided, and the eccentric part is received in an auxiliary bearing of the eccentric intermediate support. The eccentric intermediate support is configured to be pivoted about a local auxiliary axis parallel to the main axis. In this configuration, it is the eccentric intermediate support that is received in the primary bearing bored in the discoidal portion of the drum.

[0015] This provides an additional degree of freedom which allows continuous adjustment between a minimum position and a maximum position while remaining in the same radial.

[0016] According to one embodiment, the eccentric part includes a support collar. This support collar rests against the inner side of the discoid portion to axially lock the eccentric part in position when a fixing screw is tightened in the threaded hole.

[0017] According to one embodiment, the eccentric intermediate support includes a support collar. In the configuration with two eccentric pieces, each of the pieces can be provided with a support collar whose function is similar to that described above.

[0018] According to an alternative embodiment to the collar, the eccentric part may have a taper that allows retention in the bearing. The taper, open towards the inward side, axially locks the eccentric part in the bearing when the wheel screws are tightened.

[0019] In the double eccentric part configuration, each of the parts may have a taper that allows its retention in the respective bearing.

[0020] According to one embodiment, the eccentric part, and where applicable the intermediate eccentric support when present, are flush with the external surface of the discoid portion of the drum.

[0021] The wheel rim rests, preferably flat, on the outer face of the discoid portion of the drum without interfering with any of the eccentric elements.

[0022] According to one embodiment, the number of threaded holes is 4. This is a very common configuration and for which we are looking for techno-economic optimizations.

[0023] Of course, the invention is applicable to configurations with 5 threaded / tapped holes and 5 screws, as well as to configurations with 3 threaded / tapped holes and 3 screws.

[0024] According to one embodiment, hollow shapes are provided on the eccentric part to allow the insertion of a tool intended to rotate the eccentric part.

[0025] This could be, for example, two small blind holes made on the external face of the eccentric part.

[0026] According to one embodiment, recessed shapes are provided on the eccentric intermediate support to allow the insertion of a tool for rotating the eccentric intermediate support. Here again, these could be, for example, two small blind holes made on the outer face of the eccentric part.

[0027] According to one embodiment, one or more angular reference points are provided on the eccentric part and / or the intermediate eccentric support.

[0028] When a mechanic or more generally an operator turns the eccentric part or the intermediate eccentric support, the angular reference marks allow him to reach a desired position, for example among others 90°, 45°, 180°, 135°.

[0029] The present invention also relates to a rear running gear of a motor vehicle comprising at least one brake drum as defined above.

[0030] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates a brake drum in front view, according to a first embodiment; - [Fig.2] schematically illustrates a brake drum in profile view and in cut ; - [Fig.3] schematically illustrates a brake drum in front view, according to a second embodiment; - [Fig. 4] schematically illustrates in perspective a partially exploded view relating to the second embodiment; - [Fig. 5] schematically illustrates four relative positions of the parts eccentrics; - [Fig. 6] schematically illustrates in profile and cross-section a detail area of the brake drum.

[0031] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0032] A motor vehicle includes running gear equipped with a braking system. We are interested here in running gear equipped with drum brakes.

[0033] This can typically be a rear running gear of a motor vehicle.

[0034] Figures show a brake drum labeled 1.

[0035] The brake drum 1 comprises a skirt 10 generally of revolution about a principal axis of rotation denoted Al, and a discoid portion 11 generally extending perpendicularly to the axis of rotation Al. The inner wall of the skirt forms a friction track on which the friction pads of the brake shoes can rub when the brake is activated.

[0036] The discoid portion 11 comprises an internal face 16 oriented towards the inside INT and an external face 15 oriented towards the outside EXT (see also [Fig.6]).

[0037] The general structure of a brake drum is known in itself and is therefore not described in detail here. Only the elements specific to the present invention will be explicitly presented.

[0038] As illustrated in Figures 1 and 2, the discoidal portion 11 of the drum 1 includes threaded holes 2, also called tapped holes. The number of tapped holes can be 4, as shown in the illustrations. The number of tapped holes can also be 5 or 3, and it is noted here that there is no limitation on the number of tapped holes considered in the present invention.

[0039] The drum 1 is adapted to receive a vehicle wheel, more specifically the rim 8 of this wheel, as shown in [Fig. 6]. As known, a wheel fixing screw, designated 7, is screwed into the tapped hole 2 provided in the drum 1.

[0040] According to a first embodiment shown in figures 1 and 2, at each threaded hole there is provided an eccentric piece 3 also called eccentric core in which the tapped hole 2 is formed. The eccentric piece is mounted in a bearing 13 formed in the discoid part of the drum.

[0041] The axis A2 of the tapped hole is offset relative to the axis A3 of the bearing. This offset creates an eccentricity, in other words, a non-concentricity, which allows, when the eccentric part is rotated, the axis of the hole A2 to be moved relative to the axis of the drum AL

[0042] In practice, this means that the drum 1 can be adapted to receive wheel rims with a different fixing hole spacing.

[0043] The distance of the tapped hole 2 from the axis Al of the drum is denoted RL

[0044] In most cases, RI can range from 40 mm to 60 mm, with a typical value around 50 mm.

[0045] In this first embodiment, it is noted that each eccentric part 3 is received directly in a bored bearing 13 of the drum.

[0046] Figure [1] shows three different positions of the eccentric parts 3, a first position represented in solid line (maximum RI), a second position represented in short dotted line and a third position represented in longer dotted line (minimum RI).

[0047] According to one embodiment, each eccentric part 3 includes a support collar 31. This support collar 31 butts against the inner face 16 of the drum when a fixing screw 7 exerts a pulling force outwards.

[0048] As illustrated in Figures 3 to 6, according to a second embodiment, each eccentric part 3 is received in an intermediate support 4. This intermediate support 4 is also eccentric. This intermediate support may be called an eccentric ring. The axis A3 of its inner bearing 41 is offset from the axis A4 of its outer bearing surface 43, thus creating a desired eccentricity.

[0049] The eccentric part 3 is received in an auxiliary bearing 41 of the intermediate eccentric support 4. The intermediate eccentric support 4 is received in a primary bearing 14 of the drum.

[0050] The eccentric intermediate support 4 is configured to be pivoted about a local auxiliary axis A4 parallel to the main axis AL

[0051] The eccentric intermediate support 4 is mounted with a pivot joint relative to the drum around an axis A4, by means of an external straight or slightly conical cylindrical bearing 43 received in the primary bearing 14.

[0052] The eccentric part 3 is mounted with a pivot joint relative to the intermediate eccentric support 4 around an axis A3, by means of an external straight cylindrical or slightly conical bearing surface 33.

[0053] Advantageously, recessed shapes 5 are provided on the eccentric part 3 to allow the insertion of a tool (not shown) for rotating the eccentric part. The tool in question may be a pair of pointed pliers such as circlip pliers.

[0054] As illustrated in [Fig.6], these may be small blind holes which are sufficient to insert the end of the clamp and allow a torque to be applied to turn the eccentric part.

[0055] Similarly, other hollow shapes 5 are provided on the eccentric intermediate support 4 to allow the insertion of a tool intended to rotate the eccentric intermediate support 4.

[0056] In addition, one or more angular markers 6 are provided on the eccentric part 3 and / or the intermediate eccentric support 4, which serve to indicate the angular position to the mechanic.

[0057] Advantageously, the eccentric piece 3, and the intermediate eccentric support 4 if present, are flush with the external surface 15 of the discoid portion of the drum (neither recessed nor protruding). This gives a smooth and clean appearance to the external face 15 of the discoid portion 1 of the drum, except for the small blind holes discussed above.

[0058] In [Fig.5], a fully downward setting is shown on the left, an intermediate median setting is shown in the second position from the left, and an fully upward setting is shown in the third position from the left, the two eccentric elements having been rotated 180° relative to the fully downward setting.

[0059] An example of an intermediate adjustment is shown on the far right where each of the eccentric elements has been rotated approximately 45° on either side of a fully upward position.

[0060] It is therefore noted that, with a solution with two eccentric parts, the center of the threaded hole can be moved to reach any position between two extreme positions along a given radial direction.

[0061] To return to the first embodiment with a single eccentric piece per threaded hole, it is also possible to obtain any distance between a minimum and a maximum, but this requires a coordinated movement of the four eccentric pieces and this causes a small angular offset of the set of holes as illustrated by the mixed axes slightly offset on [Fig.1].

[0062] In [Fig.6], a solution is shown where the two eccentric elements, namely the eccentric part 3 and the intermediate support 4, have a certain conicity with a cone opening directed inwards.

[0063] More specifically, the eccentric part 3 comprises an external conical bearing received in a conical bearing of corresponding shape of the intermediate support 4. It follows that the eccentric part is blocked in its axial translational movement to the right.

[0064] Similarly, the intermediate eccentric support 4 has a conical outer bearing surface received in the primary bearing formed in the drum, which also has a corresponding taper. The two eccentric parts are thus prevented from moving to the right when the screw 7 exerts a pulling force to the right.

[0065] The opening angle of the conicity can be relatively small, e.g. of the order of 5° to 10°, the parts in question being substantially inelastic, this is sufficient for the retention function.

[0066] In general, any solution for a pivot joint which allows rotation around the axis of the eccentric parts while preventing other translational and rotational movements may be suitable for the function proposed here.

[0067] It is noted that the thickness of the eccentric part and the intermediate eccentric support can be identical to the local thickness of the discoid portion of the drum. In the presence of an anti-shrinkage collar as discussed above, the thickness of the eccentric part 3 and the intermediate eccentric support 4 can be a few millimeters greater than the local thickness of the discoid portion of the drum.

[0068] The threaded hole 2 can have a diameter of 12 mm. In one possible embodiment, the outside diameter of the eccentric part 3 can range from 18 mm to 25 mm. In one possible embodiment, the outside diameter of the intermediate eccentric support 4 can range from 20 mm to 32 mm.

[0069] It should be noted that all the parts shown above are made of cast iron or steel.

Claims

Demands

1. Brake drum (1) comprising a skirt (10) generally of revolution about a principal axis (A1) of rotation, and a discoid portion (11) generally extending perpendicularly to the axis of rotation, the discoid portion comprising a plurality of threaded holes (2) adapted to receive fixing screws (7) of a vehicle wheel, characterized in that each threaded hole is made in an eccentric part (3), the eccentric part being received directly or indirectly in a bored bearing (14) provided in the discoid portion, and configured to be pivoted in the bored bearing about a local axis (A3) parallel to the principal axis.

2. Brake drum according to claim 1, characterized in that it provides an eccentric intermediate support (4), and the eccentric part (3) is received in an auxiliary bearing (41) of the eccentric intermediate support and the eccentric intermediate support is configured to be pivoted about a local auxiliary axis (A4) parallel to the main axis.

3. Brake drum according to any one of claims 1 to 2, characterized in that the eccentric part (3) includes a support flange (31).

4. Brake drum according to any one of claims 1 to 3, characterized in that the eccentric part (3), and where applicable the intermediate eccentric support (4) when present, are flush with the external surface of the discoid portion of the drum.

5. Brake drum according to any one of claims 1 to 3, characterized in that the eccentric part (3) has a taper which allows retention in the bearing.

6. Brake drum according to any one of claims 1 to 5, characterized in that the number of threaded holes (2) is 4.

7. Brake drum according to any one of claims 1 to 6, characterized in that it provides hollow shapes (5) on the eccentric part to allow insertion of a tool intended to rotate the eccentric part (3).

8. Brake drum according to claim 2, characterized in that it provides hollow shapes (5) on the eccentric intermediate support to allow insertion of a tool intended to rotate the eccentric intermediate support (4).

9. Brake drum according to any one of claims 1 to 8, characterized in that one or more angular markers (6) are provided on the eccentric part (3) and / or the intermediate eccentric support (4).

10. Rear running gear of a motor vehicle comprising at least one brake drum (1) according to any one of claims 1 to 9.

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