Brake disc for motor vehicle

Abstract

The invention relates to a brake disc (1) for a motor vehicle, the brake disc (1) comprising a disc-shaped plate forming a flange (11) which extends radially around a central hub (12), at least one friction layer forming a wear layer for the brake disc (1), the at least one friction layer being bonded to the disc-shaped plate (113) via a bonding layer, and a wear mark (14) housed in the at least one wear layer, the wear mark (14) being configured to gradually appear or disappear as the brake disc (1) wears, the wear mark (14) then forming a surface visual mark which extends along the flange (11) and indicates a level of wear of the wear layer. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: Brake disc for a motor vehicle

[0001] The technical context of the present invention is that of motor vehicle braking devices. More particularly, the invention relates to a brake disc equipped with a wear indicator.

[0002] In the prior art, brake discs are known which comprise a pair of mutually spaced annular discs which form two opposing flat brake contact surfaces. When such brake discs are implemented on a braking system for a motor vehicle, then, in the event of activation of the braking system, these opposing brake contact surfaces receive a braking force applied by a brake caliper via two opposing brake pads.

[0003] During braking, the brake discs then experience frictional forces and heat buildup. The brake pads and disc brake can wear out or be damaged due to thermal degradation and material fatigue caused by the cyclical application of friction braking. The total service life of the brake pads and discs cannot be accurately determined in advance because it depends on a number of variables, so it will be different for each vehicle and driver. For this reason, periodic inspection of the brake pads and discs is necessary.

[0004] As is known, brake pads include visual or audible indications to inform about the service life of the brake pads and their state of wear. Among these wear indicators, passive and metallic wear indicators are known, located on one side of the brake pad and which emit an audible sound when the brake pads are sufficiently worn to the point where the metallic indicators come into contact with the surface of the rotor during braking.

[0005] More complex active indicators are also known which include circuits which illuminate a warning indicator when the brake pads are excessively worn.

[0006] On the other hand, brake disc wear is not as easily detectable. And regular checking of the thickness of the brake disc makes it possible to determine whether it needs to be replaced or not. These known methods are not very accurate and do not make it easy to determine the remaining life of a brake disc.

[0007] In particular, such visual inspection is not appropriate because it is not possible to determine the thickness of the wear layer of known brake discs with the naked eye. The use of micrometers is also known in order to measure certain characteristics di very small dimensions of known brake discs. However, such inspections are expensive and require knowing a minimum acceptable thickness for each brake disc available on the market, which is not easy.

[0008] Finally, these verification methods are not easy to implement on used brake discs which may have more or less significant traces of rust which further complicate the determination of the remaining thickness of the brake disc as well as its wear.

[0009] The object of the present invention is to propose a new brake disc in order to respond at least to a large extent to the preceding problems and to further lead to other advantages.

[0010] Another aim of the invention is to make it possible to easily identify wear of the brake disc and to easily plan its replacement.

[0011] Another aim of the invention is to reduce the manufacturing and maintenance costs of brake discs, by optimizing the time of their replacement.

[0012] Another object of the invention is to simplify the manufacture of such brake discs.

[0013] According to a first aspect of the invention, at least one of the aforementioned objectives is achieved with a brake disc for a motor vehicle, the brake disc comprising:

[0014] - a discoidal plate forming a flange for the brake disc;

[0015] - at least one friction layer forming an upper wear layer of the disc brake, the at least one friction layer being bonded to the disc-shaped plate via a bonding layer bonding the at least one friction layer to the disc-shaped plate.

[0016] According to the invention, the brake disc comprises a wear mark housed in the at least one wear layer.

[0017] In the context of the present invention, the discoidal plate takes the form of an annular disc intended to be placed opposite a brake pad. Such a discoidal plate has the shape of an annular disc and comprises a central opening in order to mount the brake disc on a hub for example. The discoidal plate is typically formed from a metallic material having a very high modulus of elasticity, such as for example steel.

[0018] In the context of the present invention, the at least one friction layer is associated with the discoidal plate. In other words, the at least one friction layer is deposited on the discoidal plate in order to form a wear layer for the brake disc. Each at least one friction layer is composed of particularly hard materials which are deposited and aggregated on the discoidal plate. In the context of use of the brake disc according to the invention, the brake pad collaborates with the friction layer to perform braking, the brake pad being pressed against the friction layer in order to generate significant friction forces and to carry out when braking the motor vehicle. The material used for the at least one friction layer is of the hard material type, i.e. having a high Young's modulus, in order to reduce friction wear when the caliper compresses the brake pad against the brake disc. Advantageously, the brake disc according to the invention comprises two friction layers, superimposed on each other. The at least one friction layer makes it possible to increase the service life of the brake disc according to the invention.

[0019] In the context of the present invention, the at least one friction layer is bonded to the disc-shaped plate via the bonding layer. The bonding layer is located between the disc-shaped plate and the friction layer. The bonding layer is configured to allow the wear layer to be attached and fixed to the disc-shaped plate.

[0020] In the context of the present invention, the bonding layer and the at least one wear layer are obtained by a thermal spraying process, during which the material intended to form the wear layer or the bonding layer is present in the form of powders and is sprayed into a thermal source - typically a laser beam - in which thermal source the powdered material is then heated and then melted rapidly. This melting of material leads to the formation of droplets which are projected towards the surface of the discoidal plate on which they crush, propagate and solidify. This process thus makes it possible to form one or more successive layers of specific materials which are superimposed on the discoidal plate, thus forming the bonding layer and one or more wear layers.

[0021] In the context of the present invention, the wear mark takes the form of a conformation present at the most superficial wear layer of the brake disc according to the invention. The wear mark takes the form of a visual mark - visible or not on a new brake disc - which becomes increasingly visible as the brake disc wears and, in particular, its at least one wear layer. Thus, as the wear mark is housed in the wear layer, as the latter crumbles and disappears under the effect of friction with the brake pad, the wear mark becomes visible and makes it possible to measure efficiently and very quickly a state of wear of the brake disc according to the invention. Alternatively, the wear mark takes the form of a visual mark - visible on a new brake disc and which becomes less and less visible as the brake disc wears, and in particular its at least one wear layer.Thus, as the wear mark is housed in the wear layer, as it crumbles and disappears under the effect of friction with the brake pad, the wear mark also disappears progressively and proportionally to the wear of the outer flange, making it possible to measure. effectively and very quickly the state of wear of the brake disc according to the invention.

[0022] For this purpose, the wear mark comprises at least one conformation of the type of a protrusion or, preferably, of a depression resulting from a local and inhomogeneous variation of the material used to form the at least one wear layer, in comparison with said wear layer taken outside of said wear mark. This conformation - protrusion or depression - can thus wear or be made apparent depending on the level of wear of the brake disc.

[0023] Thus, the wear mark integrated directly into the wear layer of the brake disc according to the invention makes it possible to easily measure the wear of the brake disc and its wear layer. Its integration is easy and clever because it results in a local variation of the deposition of material forming the wear layer, thus making it possible to obtain the wear mark directly during the production of the brake disc according to the invention, and not during an additional shaping operation. Finally, the integration of such a wear mark on the brake disc according to the first aspect of the invention makes it possible, by better knowing the wear of the brake disc, to optimize the time of its replacement.

[0024] The brake disc according to the first aspect of the invention advantageously comprises at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:

[0025] - the wear mark is configured to appear as the disc brake is used and the at least one wear layer wears, the at least one wear layer crumbling differentially at the wear mark. Alternatively, the wear mark is configured to disappear as the brake disc is used and the at least one wear layer wears, the at least one wear layer crumbling differentially at the wear mark. According to a first alternative embodiment, compatible with either of the variants described above, the wear mark is configured to have a geometry different from that of the at least one wear layer when the brake disc according to the first aspect of the invention wears. By way of non-limiting examples, the wear mark comprises at least one protrusion or at least one depression housed in the wear layer, each at least one protrusion and / or each at least one depression forming a visual wear indicator.According to a second alternative embodiment or complementary to the first alternative embodiment, the wear mark comprises a mechanical property, such as for example hardness, different from that of the at least one wear layer taken outside said wear mark;

[0026] - the wear mark comprises a first wear indicator which has a depth which corresponds to a predetermined minimum usable thickness of the brake disc. In the context of the present invention, the depth is considered from a surface area of ​​the wear layer and in the direction of the discoidal plate. The surface area forms an external contact surface of the brake disc, intended to be pressed against the corresponding brake pad. This advantageous configuration makes it possible to easily determine the moment at which the brake disc according to the invention is no longer usable, the first indicator becoming apparent when the level of wear of the brake disc is lower than that associated with said first indicator, and the first indicator disappearing when the level of wear of the brake disc is higher than that associated with said first indicator;

[0027] - the wear mark possibly includes a second wear indicator located at a intermediate depth between the surface area of ​​the wear layer and the discoidal plate of the brake disc according to the invention. The second wear indicator provides an indication of the remaining acceptable service life of the brake disc according to the invention. Thus, for example, the second indicator becomes visible when the first indicator has disappeared and when the level of wear of the brake disc progresses, and the second indicator disappears when the level of wear of said brake disc reaches and exceeds the level corresponding to said second indicator;

[0028] - the wear mark extends along the brake disc. In other words, the mark wear mark has dimensions and shapes which are such that they extend in a surface manner on the brake disc. In other words, the wear mark is not a point indicator. In particular, the wear mark extends according to a curvilinear director profile. In a particularly advantageous manner, the director profile is of the spiral type. In the context of the invention, it is understood that the director profile has a spiral shape when said director profile winds around the axis of rotation of the brake disc according to the invention by extending radially - simultaneously with this winding - from the outside of the brake disc towards the inside of the brake disc, or vice versa. This advantageous configuration is particularly interesting because it makes it possible to optimize the operation of the brake disc with the associated brake pad, by avoiding a lack of contact in a given area of ​​the brake pad.Indeed, if the wear mark extended around the axis of rotation of the brake disc according to a circular director profile, then this wear mark would generate an absence of localized wear on the brake pad, thus leading to a malfunction or a reduction in the braking performance of the corresponding brake system; .

[0029] - generally, the wear mark has a variable radial extension in different given angular sectors of the brake disc. In the context of the present invention, the radial extension is measured from the axis of rotation of the brake disc and perpendicular to said axis of rotation; and the angular sector is taken angularly with respect to the axis of rotation;

[0030] - the spiral forming the wear mark has at least one clockwise winding or counterclockwise;

[0031] - the spiral has at least one step around an axis of rotation of the brake disc. In other words, the spiral forming the wear mark has at least one winding around the axis of rotation. For example, the pitch between two successive windings is at least 10 mm;

[0032] - according to a preferred embodiment of the invention, the wear mark comprises a groove which extends along the at least one friction layer. The groove thus forms a depression formed in the wear layer of the brake disc. Thus, as the brake disc wears, the groove becomes more and more apparent, thus measuring the progressive wear of the brake disc and making it possible to estimate the remaining service life for said brake disc. Advantageously, the groove forming the wear mark is formed directly at the time of manufacture of the wear layer, by locally modifying - that is to say along the director profile - the deposition parameters of the material forming said wear layer, so that said material is not aggregated and deposited along said director profile. Such a modification can for example be obtained by modifying the temperature of the laser so as not to cause local melting of the powders when said laser is located at the director profile.Thus, only along the director profile, the powders forming the wear layer will not be melted and will not be aggregated to the bonding layer, thus forming a local depression and, ultimately, the groove forming the wear mark. Of course, in the context of the present invention, it is possible to modulate the shapes and aspects, in order to give any shape, any geometry and any dimension to the wear mark thus formed; .

[0033] - the groove is delimited by a transverse “U” or “V” profile;

[0034] - the transverse profile of the groove is constant along the director profile;

[0035] - the groove has a depth at least equal to a third of the thickness of the at least one wear layer;

[0036] - optionally, the groove comprises at least one step in order to mark the second wear indicator mentioned above. Each step takes, for example, the form of a counterbore made on the profile of the groove in order to form a sidewalk indicating a particular depth of wear. Thus, by multiplying the number and / or the shape of the counterbores forming said indicators, it is possible to provide more precise information on the current wear of the brake disc during its use;

[0037] - according to a first embodiment, the groove is of the through type, said groove forming a groove which extends from a friction face of the at least one wear layer opposite the discoidal plate. In other words, even when the brake disc is new, i.e. unused, the groove is visible to the naked eye. This advantageous configuration makes it possible to become aware of the existence of such a wear indicator and to facilitate the use and replacement of the brake disc according to the invention;

[0038] - according to a second embodiment, the groove is embedded in the at least one wear layer, so that the groove forms a hollow channel extending into said wear layer. In other words, when the brake disc is new, i.e. not in use, the groove is invisible to the naked eye, it only appears when the brake disc begins to wear;

[0039] - the wear mark comprises a metallic deposit. In particular, the metallic deposit has a material resistant to high temperatures.

[0040] According to a second aspect of the invention, a brake system is proposed comprising:

[0041] - a brake disc according to the first aspect of the invention or according to one of any of its improvements, the brake disc being integral with a hub of a wheel of a motor vehicle;

[0042] - a brake pad located opposite the wear layer of the brake disc;

[0043] - a caliper configured to press the brake pad against the brake disc.

[0044] According to a third aspect of the invention, there is provided a motor vehicle comprising at least one wheel equipped with a braking system in accordance with the second aspect of the invention.

[0045] Various embodiments of the invention are provided, integrating according to all of their possible combinations the different optional characteristics set out here.

[0046] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0047] [Fig.l] illustrates a front view of an exemplary embodiment of a brake disc according to the first aspect of the invention;

[0048] [Fig.2] illustrates a cross-sectional and detailed view of the brake disc illustrated in [Fig.l] and according to a first example of embodiment of the wear mark;

[0049] [Fig.3] illustrates a cross-sectional and detailed view of the brake disc illustrated in [Fig.l] and according to a second example of embodiment of the wear mark;

[0050] [Fig.4] illustrates a cross-sectional and detailed view of the brake disc illustrated in [Fig.l] and according to a third example of embodiment of the wear mark.

[0051] Of course, the characteristics, variants and different embodiments of the invention can be associated with each other, according to various combinations, to the extent that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of characteristics described below in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0052] In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

[0053] In the figures, the elements common to several figures retain the same reference.

[0054] With reference to [Fig.l], the invention relates to a brake disc 1 for a motor vehicle, the brake disc 1 comprising:

[0055] - a central hub 12 comprising fixing elements 13 to a chassis of motor vehicle;

[0056] - a discoidal plate 113 forming a flange 11 for the brake disc 1. The discoidal plate 113 extending radially around a central means of the brake disc 1 so as to form a support flange 11 for brake calipers collaborating with the brake disc 1;

[0057] - at least one friction layer forming an upper wear layer 111 of the brake disc 1, the at least one friction layer being bonded to the discoidal plate 113 via a bonding layer 112 bonding the at least one friction layer to the discoidal plate 113. The wear layer 111 is superimposed on the discoidal plate 113, via the bonding layer 112 which ensures the fixing of the wear layer 111 on the discoidal plate 113;

[0058] - a wear mark 14 housed in the at least one wear layer 111. The mark wear mark 14 extends geometrically along the flange 11 formed by the discoidal plate 113, but the wear mark 14 is located at the level of the surface layers of said flange, that is to say at the level of the wear layer 111 itself. Generally speaking, in a direction taken perpendicular to the flange, that is to say parallel to the axis of rotation 01 of the brake disc 1, the wear mark 14 is located above the connecting layer 112.

[0059] As visible in [Fig.l], the wear mark 14 extends both radially and angularly around the axis of rotation 01, so as to reduce its interaction with the brake caliper when the brake disc 1 is used. In the example illustrated in [Fig.l], the wear mark 14 follows a director profile 141 which extends in a spiral shape around the axis of rotation 01. The spiral thus formed here comprises one to two windings, but the invention is not limiting on the number of windings. Similarly, in a radial direction, that is to say perpendicular to the axis of rotation 01, a pitch between two adjacent windings of the spiral can be taken in any way, according to the needs and the geometric constraints given by the flange 11 of the brake disc 1.

[0060] FIGURES 2 to 4 illustrate several examples of embodiments of such a wear marker 14. The technical characteristics described below can of course be combined with each other in the context of the present invention.

[0061] In FIGURES 2 to 4, the wear mark 14 takes the form of a groove, that is to say a depression, a localized material recess which extends into the wear layer 111 of the brake disc 1 according to the director profile 141 mentioned previously.

[0062] In FIGURES 2 and 3, the groove is through, that is to say that the groove is an opening on an upper face of the brake disc 1 forming a contact surface 110 with a brake caliper. In other words, an upper edge 144 of the groove forming the wear mark 14 coincides with the contact surface 110 of the brake disc 1. In these exemplary embodiments, the wear mark 14 is therefore immediately visible, even when the brake disc 1 is new and not in use. On the other hand, in [Fig. 4], the wear mark 14 is embedded in the wear layer 111, so that the upper edge 144 of the groove is located below the contact surface 110 of the brake disc 1. In other words, the upper edge 144 is located in an intermediate position between the connecting layer 112 and the contact surface 110, relative to a direction taken parallel to the axis of rotation 01.In this embodiment, when the brake disc 1 is new and not used, the wear mark 14 is invisible: it only appears when the brake disc 1 reaches a first level of wear.

[0063] Thus, the depth of the groove forming the wear mark 14 can be variable in the brake disc 1 according to the invention. Generally, the depth of the wear mark 14 is uniform along the brake disc 1, but the invention also provides a wear mark 14 inclined so that its depth is different at at least two distinct points of the brake disc 1 and its wear layer 111.

[0064] With reference to FIGURES 2, 3 and 4, the shape of the groove forming the wear mark 14 can be arbitrary. In the exemplary embodiment illustrated in [Fig.2], the groove forming the wear mark 14 has a trapezoidal shape, the lateral edges 142 being inclined relative to each other. In the exemplary embodiment illustrated in [Fig.4], the groove forming the wear mark 14 has a rectangular shape, the lateral edges 142 being parallel. Finally, in the exemplary embodiment illustrated in [Fig.3], the lateral edges 142 of the groove forming the wear mark 14 form a stepped structure. This configuration is particularly advantageous because it makes it possible to display intermediate visual indicators of the wear of the brake disc 1.

[0065] In summary, the invention relates to a brake disc 1 for a motor vehicle, the brake disc 1 comprising:

[0066] - a discoidal plate 113 forming a flange 11 which extends radially around a 12 central hub;

[0067] - at least one friction layer forming a wear layer 111 for the disc of brake 1, the at least one friction layer being linked to the disc-shaped plate 113 via a connecting layer 112;

[0068] - a wear mark 14 housed in the at least one wear layer 111, the mark wear mark 14 being configured to gradually appear or disappear as the brake disc 1 wears, the wear mark 14 then forming a surface visual mark which extends along the flange 11 and indicating a level of wear of the wear layer 111.

[0069] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the different characteristics, forms, variants and embodiments of the invention can be associated with each other in various combinations insofar as they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above can be combined with each other.

Claims

Claims

1. Brake disc (1) for a motor vehicle, the brake disc (1) comprising: - a disc-shaped plate (113) forming a flange (11) for the brake disc (1); - at least one friction layer forming an upper wear layer (111) of the brake disc (1), the at least one friction layer being bonded to the disc-shaped plate (113) via a bonding layer (112) bonding the at least one friction layer to the disc-shaped plate (113); characterized in that the brake disc (1) comprises a wear mark (14) housed in the at least one wear layer (111).

2. Brake disc (1) according to the preceding claim, in which the wear mark (14) extends according to a curvilinear director profile (141), the director profile (141) being of the spiral type.

3. A brake disc (1) according to any preceding claim, wherein the wear mark (14) comprises a groove which extends along the at least one friction layer.

4. Brake disc (1) according to the preceding claim, in which the groove is delimited by a transverse “U” or “V” shaped profile.

5. Brake disc (1) according to any one of claims 3 or 4, in which the groove is of the through type, said groove forming a groove which extends from a friction face of the at least one wear layer (111) opposite the discoidal plate (113).

6. A brake disc (1) according to any one of claims 3 or 4, wherein the groove is embedded in the at least one wear layer (111), such that the groove forms a hollow channel extending into said wear layer (111).

7. Brake disc (1) according to any one of the preceding claims, in which the wear mark (14) comprises a metallic deposit.

8. Brake disc (1) according to the preceding claim, in which the metallic deposit comprises a material resistant to high temperatures.

9. Brake system comprising: - a brake disc (1) according to any one of the preceding claims, the brake disc (1) being integral with a hub (12) of a wheel of a motor vehicle; - a brake pad located opposite the wear layer (111) of the brake disc (1); - a caliper configured to press the brake pad against the brake disc (1).

10. Motor vehicle comprising at least one wheel equipped with a brake system according to the preceding claim.

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