Slanted air intake hole

Abstract

A brake pad includes a backing plate (1) having an inner surface (13) and a lining (2) secured to the inner surface (13), the lining (2) having a collection groove (3) opening onto a friction surface (26) of the lining (2), the backing plate having a suction hole (17) in fluid communication with the collection groove (3) and connected to a vacuum source, the collection groove (3) being extended at one end by a conduit (90) having an outer end (91) opening outside the friction surface (26), the conduit (90) forming a partial break with the collection groove (3). An inclination angle (δ) between the axis of the conduit (90) and the longitudinal axis (X) of the collection groove is non-zero and inclined such that airflow near the friction surface (26) of the lining (2) is not perpendicular to the friction surface.

Description

[Technical Field]

[0001] The present invention relates to a non-polluting braking system intended to be used in machines including rotating elements whose rotation it is desired to slow down, such as, for example, highway vehicles (cars, buses, trucks) or rail vehicles, and wind turbines. [Background technology]

[0002] In such braking systems, particles and dust are released by friction braking as a result of wear of the brake pads against the rotating elements, such as the vehicle wheels or the discs driven by the vehicle wheels. These particles dispersed in the surrounding environment are known to be harmful to personal health. Furthermore, with the increasing electrification of automobiles, there is an increasing need to treat dust resulting from wear in friction brake systems.

[0003] These particles and dust must therefore be captured before they are released into the surrounding environment. For this purpose, measures exist which consist in providing the lining of the disc brake or brake shoe pad with a groove connected to a vacuum source, in which the particles are evacuated and sucked in.

[0004] Thus, a brake pad 10 for a disc brake is known, comprising a backing plate 1 having an outer surface 14, an inner surface 13 and a side edge 11, and a lining 2 of friction material fixed to the inner surface 13, the lining 2 being defined by a friction surface 26, a mounting surface 20 and side edges formed by an inner edge 23, an outer edge 24, a trailing edge 21 and a leading edge 22. The lining 2 is provided with collection grooves 3 opening into the friction surface 26 and located near the trailing edge 21, and the backing plate 1 is provided with suction holes 17 in fluid communication with the collection grooves 3. The suction holes 17 are connected to a vacuum source via a fluid connection means.

[0005] However, as the lining wears during operation, a decrease in suction performance occurs. In fact, wear leads to an increase in linear load loss, which in turn forces a reduction in the flow rate of the vacuum source (e.g., turbine). This situation results in a decrease in the performance of the process of capturing particles and dust by the collection grooves.

[0006] In order to maintain constant catching performance even when the lining 2 wears, a brake pad is known in which one end of the collection groove 3 is extended by a straight pipe 90, the outer end 91 of which opens to the outside of the friction surface 26 through an inlet 911, and the inner end 92 of which opens to the collection groove 3 by an outlet 922 which forms a section break together with the groove 3, as described in Patent Document 1.

[0007] Such a pad is shown in Figures 13 to 16. In operation, the conduit 90 acts to reduce the pressure between the inlet of the conduit 911 and the collection channels 3 on either side of the conduit 90.

[0008] Optionally, the conduit 90 extends parallel to the friction surface 26 and the inner surface 13 and opens into a side edge, for example, side edge 23, as shown in Figures 13 to 15. Figure 13 is a top view of the pad. Figure 14 is a perspective view of the pad. Figure 15 is a cross-sectional view along groove 3 from Figure 14.

[0009] In another option, the conduits 90 extend perpendicular to the friction surface 26 and the inner surface 13, opening through the backing plate and onto the outer surface 14, as shown in Figure 16. This solution has the advantage that the conduits 90 can be drilled into the backing plate 1 during its manufacture, eliminating the need to form the conduits 90 in the lining 2. This simplifies and reduces the cost of manufacturing the pad 10.

[0010] Thus, a brake pad is known which includes a backing plate having an outer surface, an inner surface, and side edges, and a lining of friction material fixed to the inner surface, the lining being defined by the friction surface, a mounting surface, and side edges formed from the inner edge, the outer edge, the trailing edge, and the leading edge, the lining having at least one collection groove opening into the friction surface and located at least partially adjacent to the trailing edge, the backing plate including at least one suction hole in fluid communication with the at least one collection groove, the at least one suction hole being connected to a vacuum source via fluid communication means, the at least one collection groove being extended at at least one of its ends by a conduit whose outer end opens outside the friction surface by an inlet, and whose inner end opens into the at least one collection groove by an outlet forming a partial break with the at least one collection groove so that, during operation, a reduced pressure exists between the inlet of the conduit and the at least one collection groove passing through the conduit.

[0011] As mentioned above, the suction and capture of brake particles in the braking system is achieved by generating an air flow that enters the collection groove. Tests conducted by the inventors have shown that the greater the air velocity near the surface of the disc (or wheel), the better the effectiveness of particle capture. This means that the higher the air velocity along the friction surface of the lining, and therefore the higher the air flow rate, the more effective the particle suction.

[0012] However, to limit load losses and therefore the power of the suction source, the air flow rate into the groove must be reduced.There are therefore two competing needs. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] French Patent Application Publication No. 3076876 [Patent Document 2] French Patent Application Publication No. 3076876 [Patent Document 3] French Patent Application Publication No. 3057040 [Patent Document 4] International Publication No. 2020 / 074841 [Patent Document 5] German Patent Application Publication No. 102020107847 [Patent Document 6] French Patent Application Publication No. 3091912 [Patent Document 7] International Publication No. 2019 / 215402 [Patent Document 8] International Publication No. 2020 / 193775 Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention aims to propose a brake pad that serves to increase the speed of the air along the friction surface of the lining without increasing the flow rate of the air through the collection grooves. [Means for solving the problem]

[0015] This object is achieved in that the angle of inclination between the axis of the conduit and the longitudinal axis of the collection groove is non-zero, so that the air flow near the friction surface of the lining is not perpendicular to the friction surface.

[0016] These configurations ensure that the air flow passing through the grooves has a velocity distribution depending on the groove height, with a maximum along the friction surface of the lining, which optimizes the suction of particles in the grooves.

[0017] For example, the inclination angle may be resolved into a primary angle in a plane perpendicular to the plane of the friction surface and a secondary angle in the plane of the friction surface, the primary angle being measured in a positive direction from the plane of the friction surface towards said backing plate outside the groove around the outlet, the primary angle being included in the interval [0°, 135°].

[0018] For example, the secondary angle is zero.

[0019] For example, the outer end opens from one side of the edge.

[0020] For example, the conduits may extend through the backing plate and have their outer ends open at the outer surface or side edge of the backing plate.

[0021] For example, the at least one collection groove may consist of a single collection groove following the trailing edge.

[0022] For example, the collection groove continues to the leading edge.

[0023] For example, the collection grooves may have a C-shape or an E-shape or a circumferential shape and may run along the outer and / or inner edges.

[0024] For example, the tilt angle may be decomposed into a primary angle in a plane perpendicular to the plane of the friction surface and a secondary angle in the plane of the friction surface, where the secondary angle is measured positively from the plane outward from the collection groove in a trigonometric direction about an axis from the bottom to the top of the collection groove, and the secondary angle is not zero and is between -90° and 90°.

[0025] For example, the secondary angle is a negative value.

[0026] The invention will be better understood and its advantages will be more clearly appreciated on reading the following detailed description of embodiments given by way of non-limiting example, and in which reference is made to the accompanying drawings in which: [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a perspective view of a brake pad according to the present invention; [Figure 2] 2 is a cross-sectional view of the brake pad according to the present invention along the collection groove along line II-II of FIG. 1; [Figure 3] 10 is a cross-sectional view of a brake pad according to another embodiment of the present invention, taken along a collection groove, with the conduit opening to the side edge of the backing plate. [Figure 4] FIG. 10 is a cross-sectional view along a collection groove of a brake pad according to yet another embodiment of the present invention having conduits that open into the outer surface of the backing plate at a primary angle strictly less than 90°. [Figure 5] FIG. 10 is a cross-sectional view along a collection groove of a brake pad according to yet another embodiment of the present invention having conduits that open into the outer surface of the backing plate at a primary angle strictly greater than 90 degrees. [Figure 6] 1 is a perspective view of a brake system including a brake pad according to the present invention; [Figure 7] 10A-10C illustrate airflow through grooves for various values ​​of primary angle of the conduit of a brake pad according to the present invention. [Figure 8] 1 shows a brake pad according to the invention when the primary angle of the conduit is equal to 45° and the secondary angle θ is equal to 0°, 45° or 90°. [Figure 9] Air flow through the grooves is shown for a primary angle equal to 45° and a secondary angle equal to −50°. [Figure 10] Air flow through the grooves is shown for a primary angle equal to 45° and a secondary angle equal to 45°. [Figure 11] FIG. 10 is a perspective view of a brake pad according to another embodiment of the present invention having a C-shaped groove and a conduit at each end of the groove. [Figure 12] FIG. 10 is a top view of a brake pad according to yet another embodiment of the present invention. [Figure 13] FIG. 1 is a top view of a pad according to the prior art. [Figure 14] FIG. 1 is a perspective view of a pad according to the prior art. [Figure 15] 15 is a cross-sectional view of the brake pad from FIG. 14 taken along line XV-XV from FIG. 14 along the collection groove. [Figure 16] 15 is a cross-sectional view of the brake pad variation of FIG. 14 taken along a collection groove. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention relates to a brake pad 10 in a braking system for a rotating element 9 of a machine. The invention is described in the case where the machine is a road vehicle and the brake is a disc brake. However, the invention applies equally to brake pads for brake shoes that rub against the wheels, as used in vehicles on rails (railroads), or to brake pads used in any other industrial machine (for example in wind turbines). In all cases, braking of the rotating element of the machine is achieved by friction of the brake pad on this rotating element during rotation.

[0029] In a disc brake, braking is achieved by friction between a disc (rotating element) 9 fixed to the vehicle wheel and two brake pads 10 pressed against either side of the disc 9. The disc 9 extends in a main plane and has an axis A perpendicular to this plane as its axis of rotation. Each pad 10 extends in this main plane so that the thickness of the pad 10 extends along the axis A of rotation.

[0030] The disc 9 rotates about an axis of rotation A in a direction of rotation FW which defines a tangential direction T which is tangent to the circumference of the disc 9 and points in the direction of rotation FW, and a radial direction R which is perpendicular to the axis of rotation A in the main plane of the disc 9. These elements are shown in Figure 6 which shows a braking device mounted on the disc 9.

[0031] In the following description, the terms "inner" and "outer" refer to the edges or zones of the brake pad 10 (or its components) that are located closest and farthest, respectively, from the axis of rotation A, and the terms "front" and "rear" refer to the edges or zones of the brake pad 10 (or its components) that are located upstream and downstream, respectively, with respect to the direction of movement of particles 28 released by the lining 2 (described below), which is also the direction of rotation FW.

[0032] As shown in FIGS. 1 and 2, a brake pad 10 includes a backing plate 1, also called a base. The backing plate 1 is made of, for example, metal. The backing plate 1 is a flat plate with a substantially uniform thickness (e.g., 3 to 5 mm), and the general shape of its main plane is a trapezoid with straight or curved edges. The backing plate 1 has an inner surface 13 to which a lining 2 is attached, and an outer surface 14 opposite to and parallel to the inner surface 13. These two surfaces are joined by a side edge 11.

[0033] The brake pad 10 also includes a lining 2 made of a friction material, such as that known as "ferodo." The lining 2 is defined by a friction surface 26 (the "rubbing" surface), a mounting surface 20 opposite the friction surface 26 and fixed to the backing plate 1 (these two surfaces are parallel to each other), an inner edge 23, an outer edge 24, a trailing edge 21, and a leading edge 22. The outer edge 24, the trailing edge 21, and the leading edge 22 may be convex or linear, and the inner edge 23 may be concave or linear.

[0034] As the lining 2 wears, the friction surface 26 moves closer and closer to the backing plate 1. As a result, the thickness of the lining 2 (measured along the axis of rotation A) decreases with wear. During operation, the lining 2 (and the rotating element 9) releases particles 28 due to friction between the lining 2 and the disk 9. The trajectory of the particles 28 along the friction surface 26 is shown as a dashed line in Figure 1 (and in Figures 13 and 14).

[0035] The lining 2 is provided with at least one collection groove 3 which opens onto the friction surface 26 and is located near the trailing edge 21 .

[0036] For example, the surface area of ​​the portion of the friction surface 26 located between the trailing edge 21 and the groove 3 is less than 10% of the total surface area of ​​the friction surface 26 .

[0037] The depth of the groove(s) 3 is smaller than the height of the lining 2 (measured perpendicular to the plane of the friction surface 26), meaning that some lining 2 remains between the bottom of each groove 3 and the inner surface 13 of the backing plate 1. The distance between the bottom of each groove 3 and the inner surface 13 (measured perpendicular to this inner surface 13) is called the "residual height" and is, for example, equal to 20% of the initial height of the lining 2 (before wear). This residual height is, for example, equal to 10% of this initial height. This residual height is, for example, equal to 5% of this initial height. This residual height is, for example, equal to 1% of this initial height.

[0038] Alternatively, the depth of the groove(s) 3 is equal to the height of the lining 2, which means that the bottom of the groove(s) 3 coincides with the inner surface 13 of the backing plate 1.

[0039] Alternatively, the depth of one or more grooves 3 is greater than the height of the lining 2, which means that the groove 3 or the bottom of these grooves 3 is located within the thickness of the backing plate 1 (in other words, the groove 3 or the bottom of these grooves 3 is a throat hollowed out in the backing plate 1 without opening on the outer surface 14 except at points (see below)).

[0040] The collection groove 3, or at least one of the collection grooves 3, extends at least partially along the trailing edge 21 and may be straight or may follow the curve of the trailing edge 21. The smallest dimension of the groove 3 is the thickness of the groove 3 measured in a generally tangential direction T in the major plane of the pad 10.

[0041] For example, one or more collection channels 3 have a rectangular cross section that is constant from its upstream end to its downstream end, and therefore have a constant thickness.

[0042] The lining 2 comprises, for example, a single continuous groove which is substantially straight or which has one or more bends between two or more substantially straight sections.

[0043] Alternatively, the lining 2 is provided with pairs of disjoint collection channels 3. Disjoint channels mean that the channels are not connected to each other except via conduits 90, as explained below.

[0044] Thus, in the present invention, the lining 2 may have a single collection groove 3 (groove only), or the lining 2 may have a plurality of separate collection grooves 3. For example, the lining 2 may be provided with a second collection groove 3 (opening into the friction surface 26) in addition to the collection groove 3 located near the trailing edge 21. This second groove 3 may be located, for example, midway between the trailing edge 21 and the leading edge 22, extending from near the inner edge 23 to near the outer edge 24, and opening into either the inner edge 23 or the outer edge 24.

[0045] In summary, according to the present invention, the lining 2 comprises at least one collection groove 3, which may consist of a single collection groove at least partially following the trailing edge 21, or may consist of a plurality of separate grooves including one first groove 3a following the trailing edge 21.

[0046] In the case of a single collection groove 3, the groove may include a straight or curved segment or multiple straight or curved segments connected by bends to form a network of connected groove segments, where the collection groove 3 is convex.

[0047] An air flow 10 is generated within the collection channel 3, this air flow 10 being generated by a vacuum source (suction system) as described below.

[0048] In the following description, with reference to Figures 1 to 5, the case will be described where there is a single collection groove 3, which is extended to one of its ends by a channel 90 (see below) opening from the side of the lower edge 23. The same applies when the collection groove 3 opens from the outer edge 24. Figures 8 and 9 also show the case where the collection groove 3 is extended to one of its ends by a channel 90 opening from the side of the inner edge 23. This groove 3 does not necessarily have to be single, and there may be at least one other groove 3 in the lining 2 (not shown in these figures).

[0049] "Opening from one side of the edge" means that the conduit 90 opens at one end near the edge, either through the backing plate 1 or directly at this edge.

[0050] In either case, the conduit 90 opens at one of its ends outside the friction surface 26. Thus, the conduit 90 opens at an edge (21, 22, 23, 24), or through the backing plate 1, or into another groove.

[0051] As shown in FIGS. 1 and 2 and 3-5, the collection groove 3 is, for example, a groove continuing along the trailing edge 21 and having a first end and a second end. The longitudinal axis X of the groove 3 is parallel to the plane H of the friction surface 26 and is defined as the axis along which the groove 3 begins to extend from its first end. Thus, if the groove 3 is straight, the longitudinal axis X extends from the first end to the second end of the groove 3, and the plane V of the groove 3 is a plane perpendicular to the friction surface 26 along which the groove 3 extends. If the groove 3 is curved, the plane V is defined as the plane along which the groove 3 begins to extend from its first end. Thus, in all cases, the plane V of the groove 3 includes the longitudinal axis X.

[0052] The groove 3 terminates at its second end, near the outer edge 24 , in a blind end 31 which does not open at the outer edge 24 .

[0053] Near this blind end 31, the backing plate 1 is provided with a through suction hole 17 that opens into the groove 3. This suction hole 17 can be seen in Figure 2. Particles 28 sucked into the groove 3 therefore enter the suction hole 17 and then into a hose 40 that is part of the suction system. Air filled with these particles 28 passes from the groove 3 to the suction hole 17 (fluid connection). One end of the hose 40 is connected to the suction hole 17. These elements are shown in Figure 2.

[0054] The hose 40 is connected to a suction mechanism (not shown) which is part of a suction system and is able to suck particles 28 out of the groove 3 through the hose 40 .

[0055] The collection channel 3 is extended near its first end by a conduit 90. The conduit 90 consists of a continuous sidewall connecting the two ends and is open only at these two ends. The conduit 90 thus forms a tunnel. This tunnel is straight, and therefore the axis of the conduit 90 is straight, which allows for its drilling. Alternatively, the tunnel is curved. In this case, the axis of the conduit 90 is defined as the axis where the conduit 90 begins to extend from the collection channel 3 (meaning starting from the inner end 92 of the conduit 90; see definition below).

[0056] Advantageously, as in the case where the conduits 90 are perforated, the cross section of the conduits 90 remains constant throughout the life of the pad 10, maintaining the ability for the collection grooves to suck up particles 28.

[0057] Conduit 90 opens at its outer end 91 from the side of inner edge 23 by an inlet 911. Conduit 90 opens at its inner end 92 in collection groove 3 by an outlet 922. Outlet 922 forms a partial break with groove 3, which means that the section increases abruptly (step-like) when passing from conduit 90 to groove 3.

[0058] The increased cross section can be seen in FIG. 2, which is a cross section along line II-II from FIG. 1, meaning the entire length of the collection groove 3 and conduit 90 from inner edge 23 to outer edge 24.

[0059] Due to this sudden increase in cross section (in the general direction of air flow), during operation there is a reduced pressure on each side of the conduit 90, i.e. along the conduit 90, between the inlet 911 and the collection groove 3.

[0060] Furthermore, according to the present invention, the axis of the conduit 90 makes a non-zero angle δ with the longitudinal axis X of the groove 3. The angle δ is called the inclination angle and is illustrated in Figure 8. Therefore, in general, the inclination angle δ can be resolved into a primary angle β in a vertical plane (e.g., plane V) perpendicular to the plane of the friction surface 26 (plane H), and a secondary angle θ in the plane H of the friction surface 26.

[0061] In particular, the secondary angle θ is zero and the conduit 90 is inclined only in the plane V of the groove 3 according to the primary angle β.

[0062] In another particular case, the primary angle β is zero and the conduit 90 is inclined only in a plane parallel to the plane H of the friction surface 26 according to the secondary angle θ.

[0063] The primary angle β is measured positively from the plane H of the friction surface 26 toward the backing plate 1, toward the outside of the groove 3 around the outlet 922. The primary angle β is always positive. Thus, air passing through the conduit 90 from the inlet 911 toward the outlet 922 is always directed toward the friction surface 26, except in the other specific case described above. In fact, in this other specific case, the primary angle β is zero and the secondary angle θ is not zero, so that the air leaves the conduit 90 in a plane parallel to the plane H of the friction surface 26.

[0064] The secondary angle θ is measured from plane V (in plane H) towards the outside of groove 3, positively in the trigonometric direction about an axis running from the bottom to the top of groove 3.

[0065] If the conduit 90 is straight, the axis of the conduit 90 is the line connecting the center of the inlet 911 and the center of the outlet 922. If the conduit 90 is curved, the axis of the conduit 90 is considered to be the tangent to the curve connecting the centers of the cross sections of the conduit 90 at the center of the outlet 922.

[0066] In the specific case where the secondary angle θ is zero, meaning that the conduit 90 is inclined only in the plane V of the groove 3 along the primary angle β, the presence of a strictly positive (and therefore non-zero) primary angle β means that the airflow passing through the groove 3 upon exiting the conduit 90 has a velocity distribution with a height of the groove 3 that is maximum along the friction surface 26 of the lining. Surprisingly, this distribution has been experimentally observed by the inventors. Figure 7 shows the velocity distributions obtained when the inclination angle δ is zero (Figure 7(a)), when the inclination angle δ is equal to 45° and the secondary angle θ is zero (Figure 7(b)), when the inclination angle δ is equal to 75° and the secondary angle θ is zero (Figure 7(c)), and when the inclination angle δ is equal to 135° and the secondary angle θ is zero (Figure 7(d)). The region M of the groove 3 where the velocity is maximum is enclosed by a dashed line. It should be noted that in case (a) (when the conduit 90 is not inclined), the region M is located near the bottom of the groove 3, i.e., the inner surface 13. In contrast, in cases (b), (c), and (d) where the conduit 90 is inclined in the plane V of the groove 3, the region M is located along the friction surface 26.

[0067] Tests performed by the inventors have shown that the results shown in Figure 7 for the longitudinal velocity (along the longitudinal axis X) near the friction surface 26 when the secondary angle θ is zero remain qualitatively the same for all values ​​of the secondary angle θ (meaning between -90° and 90°). Thus, although this longitudinal velocity varies between two values ​​(absolute values) of the secondary angle θ, this longitudinal velocity is the same for two opposite secondary angles θ having the same absolute value.

[0068] According to the invention, the inclination angle δ between the axis of the conduit 90 and the longitudinal axis X of the groove 3 is not zero and is inclined so that the air flow near the friction surface 26 of the lining 2 is not perpendicular to the friction surface. In particular, the inclination angle δ is not perpendicular to the plane H of the friction surface 26. Indeed, in this case (primary angle β=90°, secondary angle θ=0), the air flow generated in the groove 3 has a non-maximum longitudinal velocity near the friction surface 26 and the transverse velocity of this air flow (velocity perpendicular to the longitudinal axis X near the friction surface 26) is zero. This is therefore the case when the air flow near the friction surface 26 is not optimal.

[0069] Furthermore, tests carried out by the inventors have shown that when the secondary angle θ is included in the interval [−15°, 15°] and the primary angle β is included in the angle [60°, 85°], the overall velocity distribution (the overall velocity is the vector sum of the longitudinal and transverse velocities) is maximum and is essentially along the friction surface 26.

[0070] These tests also show that the transverse velocity of the airflow is not negligible (meaning it is not zero, but is of the same order of magnitude as the longitudinal velocity of the airflow) under the following two conditions: - A first configuration in which the primary angle β is less than 40° and the secondary angle θ is outside the range [-10°, 10°]. - A second configuration in which the primary angle β is greater than 40° and the secondary angle θ is outside the range [-20°, 20°].

[0071] In the first embodiment, as shown in FIGS. 1 and 2, the conduit 90 opens at the lower edge 23 near its inlet 911.

[0072] Thus, during operation, air flows from the inlet 911 through the duct 90 to the outlet 922, then through the groove 3 to the suction holes 17 and then through the hose 40, allowing the evacuation of particles and particles 28 present in the air. This air circulation is specific to the case shown in Figures 1 to 5.

[0073] Conduit 90 has a constant circular cross section, or conduit 90 has non-circular sections and / or variable sections.

[0074] Advantageously, the inlet 911 opens in the zone of the inner edge 23 (or, in the general case, one of the edges (21, 22, 23, 24) of the lining 2) that is closest to the backing plate 1 and that will not be consumed at the end of the normal operating time (life) of the pad 10. The inlet 911 therefore opens at a distance from the inner surface 13 of the backing plate 1 that is greater than the residual height of the lining 2 (see above).

[0075] Thus, throughout the life of the pad 10, the cross section of the conduit 90 remains constant and the ability for the collection grooves to suck up particles 28 is maintained.

[0076] When the conduit 90 is positioned at a height equal to this residual height, the conduit 90 acts as a visual wear indicator: in fact, the wear of the lining 2 to the conduit 90 indicates that the pad 10 has reached the end of its life.

[0077] 3 and 5, the conduit 90 does not open near its inlet 911 at the lower edge 23. In contrast, the conduit 90 passes from the collection groove 3 through the backing plate 1 and opens near its inlet 911 in the backing plate 1. This solution has the advantage that the conduit 90 can be drilled into the backing plate 1 during its manufacture, and there is no need to form the conduit 90 in the lining 2. This simplifies and reduces the costs of manufacturing the pad 10. The outlet 922 is always located near the inner surface 13 of the backing plate 1.

[0078] In one of these embodiments (the second embodiment), as shown in Figure 3, the inlet 911 opens into the side edge 11 of the backing plate 1. In this case, the primary angle β is necessarily strictly less than 90°.

[0079] In another of these embodiments (third embodiment), as shown in Figures 4 and 5, the inlet 911 opens into the outer surface 14 of the backing plate 1. The primary angle β is therefore necessarily strictly less than 180°. Figure 4 shows the case where the primary angle β is included in the interval ]0°, 90°[. Figure 5 shows the case where the primary angle β is included in the interval ]90°, 180°[.

[0080] In the embodiment described above and shown in Figures 2 to 5 and 7, the axis of the conduit 90 lies in the plane V of the groove 3. The secondary angle θ is therefore zero.

[0081] In another embodiment, the axis of the conduit 90 makes a secondary angle θ with the longitudinal axis X of the groove 3 that is non-zero and is comprised between −90° and 90°.

[0082] This other embodiment is shown in Figure 8(b) when the secondary angle θ is equal to 45° and in Figure 8(c) when the secondary angle θ is equal to 90°. For reference, Figure 8(a) shows the case when the secondary angle θ is equal to 0°, and the tilt angle δ is equal to the primary angle β. In Figure 8, in the three cases (a), (b), and (c), the primary angle β is equal to 45° as an example.

[0083] This alternative embodiment has a further advantage compared to the embodiment in which the secondary angle θ is zero: in fact, particles generated by friction between the lining and the vehicle disc (or wheel) are naturally carried along the friction surface 26 transversely to the groove 3 (arrow 28 in FIG. 1 ). These particles therefore tend to pass through the groove 3 and escape into the atmosphere without entering the groove 3, which is problematic.

[0084] Surprisingly, tests carried out by the inventors have shown that non-zero secondary angle data can generate transverse air flows (perpendicular to the longitudinal axis X) with vortices near the friction surface 26 that are directed in the opposite direction to the flow of these particles (arrows 28). Such air flows therefore contribute to preventing the escape of particles from the grooves 3.

[0085] This transverse airflow, which contributes to preventing particles from escaping from the groove 3, is generated, more specifically, when the secondary angle θ is negative. This occurs, in particular, when the secondary angle θ is within the interval [−80°, −10°]. FIG. 9 shows the airflow in an example where the primary angle β is equal to 45° and the secondary angle θ is equal to −50°. Arrow P1 indicates the direction of most of the airflow, particularly near the friction surface 26. It can be seen that this flow proceeds in the opposite direction to the flow of particles along the friction surface (arrow P1 is collinear with arrow 28 and points in the opposite direction). Therefore, the airflow from the conduit 90 contributes to forcing particles into the groove 3. Tests conducted by the inventors have shown that the transverse velocity of this airflow is greatest for a primary angle β in the interval [25°, 75°] and a secondary angle θ in the interval [−50°, −25°].

[0086] Experiments conducted by the inventors for several positive values ​​of the secondary angle θ have shown that a transverse air flow is generated near the friction surface 26 that does not prevent or even promote the escape of particles from the groove 3. Therefore, these values ​​of the secondary angle θ correspond to an unfavorable situation. Figure 10 shows an example in which the primary angle β is equal to 45° and the secondary angle θ is equal to 45°. Arrow P2 indicates the direction of the majority of the air flow, especially near the friction surface 26. It can be seen that this flow proceeds in the same direction as the flow of particles along the friction surface (arrow P2 is on the same line and in the same direction as arrow 28). Therefore, the air flow from the conduit 90 contributes to carrying particles into the groove 3.

[0087] A further embodiment of the present invention will now be described with reference to Figure 11. Figure 11 shows a brake pad for the railway application.

[0088] Collection groove 3 is a single C-shaped groove that extends along trailing edge 21 and leading edge 22. The center of collection groove 3 connects the front and rear portions of collection groove 3 along outer edge 24. The rear portion of collection groove 3 (the portion along trailing edge 21) is extended to near the first end by a duct 90 that opens from the inner edge 23 side. The front portion of collection groove 3 (the portion along leading edge 22) is extended to near the second end of collection groove 3 by another duct 90 that opens from the inner edge 23 side.

[0089] Each of these conduits 90 is similar to one of the conduits 90 described with reference to Figures 1 to 5. Alternatively, each of these two conduits 90 has a different geometry than the other conduit 90, e.g., different sections for balancing flow rates.

[0090] As shown in Figure 11, the backing plate 1 has through suction holes 17 that open to the rear of the grooves 3, in which the grooves 3 are widened (although the grooves 3 may not be widened in this region). Alternatively, the suction holes 17 open to the front or center of the grooves 3. In either case, the suction holes 17 are located away from the ends of the collection grooves 3.

[0091] In the above embodiment, the lining 2 is provided with a single groove 3 .

[0092] In yet another embodiment of the invention, the lining 2 comprises a plurality of separate collection grooves 3. The following configurations are possible:

[0093] In the first configuration, at least one conduit 90 opens at its inner end 92 into one end of one of the grooves 3 and at its outer end 91 from the side of one of the edges (21, 22, 23, 24) of the lining 2.

[0094] In the second configuration, at least one conduit 90 opens at its inner end 92 into one end of one groove 3 and at its outer end 91 into one end of another groove 3 .

[0095] In a third configuration that combines the first and second configurations, at least one conduit 90 opens at its inner end 92 into one end of one groove 3 and at its outer end 91 from the side of one edge (21, 22, 23, 24) of the lining 2, and at least one other conduit 90 opens at its inner end 92 into one end of one groove 3 and at its outer end 91 into one end of another groove 3.

[0096] 12 shows an example of a second configuration in which the lining 2 only comprises two separate collection grooves 3, specifically a first groove 3a and a second groove 3b, which are in line with each other and extend along the trailing edge 21. A single conduit 90 extends between the first end of the first groove 3a and the first end of the second groove 3b.

[0097] Thus, at its outer end 91, the conduit 90 opens into the second groove 3b by an inlet 911. The inner end 92 of the conduit 90 opens into the first groove 3a by an outlet 922. The outlet 922 is located at a first end of the first groove 3a.

[0098] The second end of the first groove 3a is a blind end 31 that does not open to the outer edge 24. Near this blind end 31, the backing plate 1 has a through suction hole 17 that opens into the groove 3.

[0099] The second end of the second groove 3 b opens to the inner edge 23 .

Claims

1. A brake pad (10), A backing plate (1) having an outer surface (14), an inner surface (13) and side edges (11), and a lining (2) of friction material secured to the inner surface (13), The lining (2) is defined by a friction surface (26), a mounting surface (20), and side edges formed from an inner edge (23), an outer edge (24), a trailing edge (21) and a leading edge (22), the lining (2) comprising at least one collection groove (3) opening into the friction surface (26) and located at least partially adjacent to the trailing edge (21); the backing plate includes at least one suction hole (17) in fluid communication with the at least one collection groove (3); said at least one suction hole (17) being connectable to a vacuum source to generate an air flow; said at least one collection groove (3) is extended at at least one of its ends by a conduit (90) whose outer end (91) opens outwardly of said friction surface (26) by an inlet (911), and whose inner end (92) opens into said at least one collection groove (3) by an outlet (922) forming a partial break with said at least one collection groove (3) so that, in operation, a reduced pressure exists between said inlet (911) of said conduit (90) and said at least one collection groove (3) passing through said conduit (90); The brake pad (10) has a non-zero inclination angle (δ) between the axis of the conduit (90) and the longitudinal axis (X) of the at least one collection groove (3), so that the air flow near the friction surface (26) of the lining (2) is not perpendicular to the friction surface (26) during operation.

2. 2. The brake pad of claim 1, wherein the tilt angle (δ) is resolved into a primary angle (β) in a plane (V) perpendicular to the plane (H) of the friction surface (26) and a secondary angle (θ) in the plane (H) of the friction surface (26), the primary angle (β) being measured in a positive direction from the plane (H) of the friction surface (26) toward the backing plate (1) outside the at least one collection groove (3) and around the outlet (922), and the primary angle (β) is included in the interval [0°, 135°].

3. The brake pad of claim 2 wherein the secondary angle (θ) is zero.

4. 4. A brake pad according to claim 3, wherein said outer end (91) opens from one side of said lateral edges (21, 22, 23, 24) of said lining.

5. 4. The brake pad of claim 3, wherein the conduit (90) passes through the backing plate (1) and the outer end (91) opens into the outer surface (14) or the side edge (11) of the backing plate (1).

6. 2. A brake pad according to claim 1, wherein said at least one collecting groove (3) consists of a single collecting groove following said trailing edge (21).

7. 7. A brake pad according to claim 6, wherein said single collecting groove (3) further continues to said leading edge (22).

8. 8. The brake pad according to claim 7, wherein the single collection groove (3) has a C-shape, an E-shape, or a circumferential shape, and the single collection groove continues along the outer edge (24) and / or the inner edge (23).

9. 2. The brake pad of claim 1, wherein the tilt angle (δ) is resolved into a primary angle (β) in a plane (V) perpendicular to the plane (H) of the friction surface (26) and a secondary angle (θ) in the plane (H) of the friction surface (26), the secondary angle (θ) being measured positively from the plane (H) towards the outside of the at least one collection groove (3) in a trigonometric direction around an axis going from the bottom to the top of the at least one collection groove (3), the secondary angle (θ) being non-zero and being comprised between -90° and 90°.

10. The brake pad of claim 9, wherein the secondary angle (θ) is negative.

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