Brake disc for motor vehicle

Abstract

The invention relates to a brake disc (1) for a motor vehicle, the brake disc (1) comprising a discoidal 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 discoidal plate (113) by means of a bonding layer, and a wear indicator (14) housed in the at least one wear layer, the wear indicator (14) being configured to progressively appear or disappear as the brake disc (1) wears, the wear indicator (14) thus forming a surface visual marker 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 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 that form two opposing flat brake contact surfaces. When such brake discs are used in a motor vehicle braking system, then, upon 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 are subjected to frictional forces and heat buildup. The brake pads and disc brake can wear 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 precisely determined in advance because it depends on a number of variables, and will therefore differ 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 indicators to provide information on the remaining service life and wear level of the brake pads. Among these wear indicators are known passive metallic wear indicators located on one side of the brake pad that emit an audible sound when the brake pads are sufficiently worn to the point where the metallic indicators come into contact with the rotor surface during braking.

[0005] We also know of more complex active indicators which include circuits which light up a warning indicator when the brake pads are too worn.

[0006] On the other hand, brake disc wear is not as easily detectable. Regularly checking the brake disc thickness helps determine whether or not it needs replacing. These known methods are not very precise and do not allow for easy determination of the remaining service life of a brake disc.

[0007] In particular, such a 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 for measuring certain characteristics is also known. very small dimensional dimensions of known brake discs. However, such inspections are costly and require knowing a minimum acceptable thickness for each brake disc available on the market, which is not obvious.

[0008] Finally, these verification methods are not easy to implement on used brake discs which may show 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 present invention aims to provide a new brake disc in order to address at least largely the previous problems and to lead to other advantages.

[0010] Another object of the invention is to make it easy to identify wear on the brake disc and to be able to easily plan its replacement.

[0011] Another objective of the invention is to reduce the manufacturing and maintenance costs of brake discs, by optimizing the timing 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 of brake, at least one friction layer being linked to the discoidal plate via a bonding layer linking at least one friction layer to the discoidal plate.

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

[0017] In the context of the present invention, the disc-shaped mounting plate takes the form of an annular disc intended to be positioned opposite a brake pad. Such a disc-shaped mounting plate has the shape of an annular disc and includes a central opening for mounting the brake disc onto a hub, for example. The disc-shaped mounting plate is typically made of a metallic material having a very high modulus of elasticity, such as steel.

[0018] In the context of the present invention, at least one friction layer is associated with the disc plate. In other words, at least one friction layer is deposited on the disc plate to form a wear layer for the brake disc. Each at least one friction layer is composed of particularly hard materials that are deposited and bonded to the disc plate. In the context of using the brake disc according to the invention, the brake pad interacts with the friction layer to achieve braking. The brake pad is pressed against the friction layer to generate significant frictional forces and bring the motor vehicle to a stop. The material used for at least one friction layer is a hard material, i.e., one with a high Young's modulus, to reduce wear from friction when the caliper compresses the brake pad against the brake disc. Advantageously, the brake disc according to the invention comprises two friction layers, one superimposed on the other. This at least one friction layer increases the service life of the brake disc according to the invention.

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

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

[0021] In the context of the present invention, the wear indicator takes the form of a feature present in the outermost wear layer of the brake disc according to the invention. The wear indicator takes the form of a visual marker—visible or not on a new brake disc—which becomes increasingly visible as the brake disc wears, and in particular as at least one of its wear layers wears. Thus, since the wear indicator is embedded in the wear layer, as the latter wears away and disappears due to friction with the brake pad, the wear indicator becomes apparent and allows for an efficient and very rapid measurement of the brake disc's wear according to the invention. Alternatively, the wear indicator takes the form of a visual marker—visible on a new brake disc—which becomes less and less visible as the brake disc wears, and in particular as at least one of its wear layers wears.Thus, as the wear indicator is embedded in the wear layer, as the latter crumbles and disappears under the effect of friction with the brake pad, the wear indicator also disappears. progressive and proportional to the wear of the outer flange, allowing for efficient and very rapid measurement of the wear condition of the brake disc according to the invention.

[0022] To this end, the wear indicator comprises at least one protrusion or, preferably, a depression resulting from a local and inhomogeneous variation in the material used to form at least one wear layer, compared to said wear layer outside said wear indicator. This protrusion or depression can thus wear away or become apparent depending on the level of wear of the brake disc.

[0023] Thus, the wear indicator integrated directly into the wear layer of the brake disc according to the invention makes it easy to measure the wear of the brake disc and its wear layer. Its integration is simple and ingenious because it results in a local variation in the material deposit forming the wear layer, thereby allowing the wear indicator to be obtained directly during the manufacturing of the brake disc according to the invention, and not during an additional shaping operation. Finally, the integration of such a wear indicator on the brake disc according to the first aspect of the invention makes it possible, by better understanding the wear of the brake disc, to optimize the timing of its replacement.

[0024] The brake disc conforming 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 indicator is configured to appear as the disc of The brake is used and at least one wear layer wears away, with at least one wear layer eroding differentially at the wear indicator. Alternatively, the wear indicator is configured to disappear as the brake disc is used and at least one wear layer wears away, with at least one wear layer eroding differentially at the wear indicator. According to a first embodiment, compatible with either of the above-described embodiments, the wear indicator is configured to have a different geometry from that of at least one wear layer as the brake disc wears, in accordance with the first aspect of the invention. By way of non-limiting example, the wear indicator comprises at least one protrusion or at least one depression embedded 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 or complementary embodiment to the first embodiment, the wear marker has a mechanical property, such as hardness, different from that of at least one wear layer taken outside said wear marker; .

[0026] - the wear indicator includes 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 superficial area of ​​the wear layer towards the disc plate. The superficial area forms an external contact surface of the brake disc, intended to bear against the corresponding brake pad. This advantageous configuration makes it easy to determine when the brake disc according to the invention is no longer usable, the first indicator becoming visible when the wear level of the brake disc is less than that associated with said first indicator, and the first indicator disappearing when the wear level of the brake disc is greater than that associated with said first indicator;

[0027] - the wear indicator may include a second wear indicator located at an 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 wear level of the brake disc progresses, and the second indicator disappears when the wear level of said brake disc reaches and exceeds the level corresponding to said second indicator;

[0028] - the wear indicator extends along the brake disc. In other words, the indicator The wear indicator has dimensions and shapes such that it extends over the surface of the brake disc. In other words, the wear indicator is not a point indicator. In particular, the wear indicator extends along a curvilinear guide profile. Advantageously, the guide profile is spiral-shaped. In the context of the invention, it is understood that the guide profile has a spiral shape when said guide profile winds around the axis of rotation of the brake disc according to the invention, extending radially—simultaneously with this winding—from the outside of the brake disc to the inside of the brake disc, or vice versa. This advantageous configuration is particularly beneficial because it optimizes the operation of the brake disc with the associated brake pad, preventing a loss of contact in a given area of ​​the brake pad.Indeed, if the wear indicator extended around the axis of rotation of the brake disc according to a circular guide profile, then this wear indicator would generate a lack 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 speaking, the wear indicator has a variable radial extension in different given angular sectors of the brake disc. In the context of the In 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 indicator has at least one clockwise or counterclockwise;

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

[0032] - according to a preferred embodiment of the invention, the wear indicator comprises A groove extends along at least one friction layer. This groove creates a depression in the brake disc's wear layer. As the brake disc wears, the groove becomes increasingly prominent, thus measuring the progressive wear and allowing for an estimation of its remaining service life. Advantageously, the groove forming the wear indicator is created directly during the manufacturing of the wear layer by locally modifying—along the guide profile—the deposition parameters of the material forming the wear layer. This modification prevents the material from clumping and being deposited along the guide profile. Such a modification can be achieved, for example, by adjusting the laser temperature to prevent local melting of the powders when the laser is positioned at the guide profile.Thus, only along the guiding profile will the powders forming the wear layer not melt and not aggregate with the bonding layer, thereby forming a local depression and, ultimately, the groove forming the wear marker. Of course, in the context of the present invention, it is possible to modulate the shapes and appearances in order to give any shape, any geometry, and any size to the wear marker thus formed.

[0033] - the groove is delimited by a transverse profile in a "U" or "V" shape;

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

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

[0036] - optionally, the groove includes at least one bearing in order to mark the The second wear indicator mentioned earlier. Each bearing, for example, takes the form of a counterbore cut into the groove profile to form a raised edge indicating a particular wear depth. Thus, by increasing the number and / or shape of the counterbores forming these indicators, it is possible to provide more precise information regarding the ongoing wear of the brake disc during its use;

[0037] - according to a first embodiment, the groove is of the through type, said a groove forming a channel extending from a friction face of at least one wear layer opposite the disc 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 the existence of such a wear indicator readily apparent and facilitates the use and replacement of the brake disc according to the invention;

[0038] - according to a second embodiment, the groove is embedded in 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. unused, the groove is invisible to the naked eye; it only appears when the brake disc begins to wear;

[0039] - the wear indicator has a metallic deposit. In particular, the metallic deposit It contains a material resistant to high temperatures.

[0040] According to a second aspect of the invention, a braking 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 wheel hub 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, a motor vehicle is proposed comprising at least one wheel equipped with a braking system conforming to the second aspect of the invention.

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

[0046] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given with reference to the accompanying schematic drawings on the other hand, in which:

[0047] [Fig. 1] illustrates a front view of an example of an embodiment of a brake disc conforming to the first aspect of the invention;

[0048] [Fig.2] illustrates a cross-sectional and detailed view of the brake disc shown on the [Fig.l] and according to a first example of the realization of the wear marker;

[0049] [Fig.3] illustrates a cross-sectional and detailed view of the brake disc shown on the [Fig.l] and according to a second example of realization of the wear marker;

[0050] [Fig.4] illustrates a cross-sectional and detailed view of the brake disc shown on the [Fig.l] and according to a third example of the realization of the wear marker.

[0051] Of course, the features, variants, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features, described hereafter in isolation from the other described features, if this selection of features 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 are combinable 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. 1], 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, at least one friction layer being linked to the disc plate 113 via a bonding layer 112 linking at least one friction layer to the disc plate 113. The wear layer 111 is superimposed on the disc plate 113, via the bonding layer 112 which ensures the attachment of the wear layer 111 to the disc plate 113;

[0058] - a wear marker 14 housed in at least one wear layer 111. The marker The wear mark 14 extends geometrically along the flange 11 formed by the discoidal plate 113, but the wear indicator 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 indicator 14 is located above the bonding layer 112.

[0059] As can be seen in [Fig. 1], the wear indicator 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 the [Fig. 1], the wear indicator 14 follows a guide profile 141 which extends in a spiral shape around the axis of rotation 01. The spiral thus formed has one or two windings, but the invention is not limiting to the number of windings. Similarly, in a radial direction, i.e., perpendicular to the axis of rotation 01, the 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 the realization 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 marker 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 directional profile 141 mentioned previously.

[0062] In FIGURES 2 and 3, the groove is through-groove, that is, 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 indicator 14 coincides with the contact surface 110 of the brake disc 1. In these embodiments, the wear indicator 14 is therefore immediately visible, even when the brake disc 1 is new and unused. In contrast, in [Fig.4], the wear marker 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 bonding layer 112 and the contact surface 110, relative to a direction taken parallel to the axis of rotation 01.In this example, when brake disc 1 is new and unused, the wear indicator 14 is invisible: it only appears when brake disc 1 reaches a first level of wear.

[0063] Thus, the depth of the groove forming the wear indicator 14 can be variable in the brake disc 1 according to the invention. Generally, the depth of the wear indicator 14 is uniform along the brake disc 1, but the invention also provides for an inclined wear indicator 14 such that its depth differs at at least two distinct points on 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 indicator 14 can be arbitrary. In the embodiment illustrated in [Fig. 2], the groove forming the wear indicator 14 has a trapezoidal shape, with the lateral edges 142 inclined relative to each other. In the embodiment illustrated in [Fig. 4], the groove forming the wear indicator 14 has a rectangular shape, with the lateral edges 142 parallel. Finally, in the embodiment illustrated on In [Fig. 3], the lateral edges 142 of the groove forming the wear indicator 14 form a stepped structure. This configuration is particularly advantageous because it allows for intermediate visual indicators of brake disc wear 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 central hub 12;

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

[0068] - a wear marker 14 housed in at least one wear layer 111, the marker 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 marker 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 just described, and many modifications can be made to these examples without departing from the scope of the invention. In particular, the various features, forms, variants, and embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above are combinable.

Claims

Demands

1. Brake disc (1) for motor vehicle, the brake disc (1) comprising: - a discoidal 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 linked to the discoidal plate (113) by means of a bonding layer (112) linking the at least one friction layer to the discoidal plate (113); characterized in that the brake disc (1) comprises a wear marker (14) housed in the at least one wear layer (111), the wear marker (14) extending along a curvilinear directional profile (141), the directional profile (141) being of the spiral type having at least one pitch around an axis of rotation of the brake disc (1).

2. Brake disc (1) according to any one of the preceding claims, wherein the wear indicator (14) has a groove extending along at least one friction layer.

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

4. Brake disc (1) according to any one of claims 2 or 3, wherein the groove is of the through type, said groove forming a groove which extends from a friction face of at least one wear layer (111) opposite the disc plate (113).

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

6. Brake disc (1) according to any one of the preceding claims, wherein the wear marker (14) has a metallic deposit.

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

8. Braking system comprising:

9. - 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). Motor vehicle comprising at least one wheel equipped with a braking system according to the preceding claim.

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