Assembly for braking a railway vehicle

Abstract

TITLE: Braking Assembly for a Railway Vehicle A railway vehicle assembly comprising: a wheel (10) including a tread (11) delimited by a wheel sidewall (12) and a flange (13); and a brake pad (1) including a lining (3) delimited by a friction face (31) for contacting the tread (11), an inner edge (34), and an outer edge (33), the lining (3) having a particle collection groove (4) comprising: a front portion (41) and a rear portion (42), and a connecting portion (43) linking the front (41) and rear (42) portions, and extending, for at least 50% of its length, near the outer edge (33) of said lining (3), the outer edge (33) being axially disposed closer to the wheel sidewall (12) than to the flange (13). Figure 3

Description

Title of the invention: Assembly for braking a railway vehicle. Technical field.

[0001] This disclosure relates to braking systems with brake pads, intended, but not limited to, railway rolling stock. Prior art

[0002] Conventionally, vehicle braking systems comprise one or more brake pads or shoes which, during braking, press against a rotating element, thus braking the vehicle. In particular, in railway vehicles such as trains, trams, or metros, braking is achieved by means of a shoe brake, also called a tread brake or TBU (Tread Brake Unit). In this type of brake, the brake pad, also called a shoe or shoe, presses against a radially external surface of a moving wheel of the railway vehicle during braking.

[0003] The brake shoe pad comprises a lining made of friction material. One face of this lining, which comes into contact with the wheel during braking, called the friction face, as well as the wheel itself, gradually wears down by abrasion, generating particles. Since these particles are pollutants, it is necessary to limit their release into the environment. To this end, the lining is conventionally equipped with a particle collection groove that is completely open on the friction face and extends across almost the entire width of the pad. This groove is fluidly connected to a vacuum source capable of drawing in the collected particles.

[0004] The groove is conventionally cut into the lining to form a channel capable of guiding an airflow carrying the collected particles. During braking, the lining is pressed against the wheel, which generates significant stresses on the lining. The inventors, during their research, determined that brake pads with collection grooves could exhibit mechanical fragility affecting their lifespan.

[0005] The purpose of this disclosure is therefore to mitigate at least in part the disadvantages of the prior art mentioned above.

[0006] In particular, one objective of this disclosure is to propose a solution that reduces the risk of breakage of the lining by improving its properties mechanical, while ensuring satisfactory efficiency in collecting braking particles. Summary

[0007] The objectives mentioned above are achieved in particular by a railway vehicle assembly comprising:

[0008] a wheel defining an axial direction, and comprising a tread delimited externally by a wheel sidewall and internally by a flange; and a brake pad comprising a backing plate and at least one lining made of a friction material, the at least one lining being fixed to said backing plate and being delimited by a friction face configured to contact the tread of said wheel, a fixing face on the backing plate, an inner edge, an outer edge, a rear edge and a front edge, the at least one lining further comprising a particle collection groove open on the friction face, said collection groove being in fluid communication with a conduit opening out of the friction face and with a suction hole suitable for connection to a vacuum source, said collection groove comprising: - a front portion extending at least partly near the front edge; - a rear portion extending at least partially near the rear edge of said trim; and - a connecting portion fluidly linking the front portion and the rear portion, said connecting portion having a circumferential length, the connecting portion extending, for at least 50% of its circumferential length, near the outer edge of said lining, the outer edge being arranged axially closer to the wheel sidewall than to the flange.

[0009] Thus, in a particularly effective manner, an assembly according to the present disclosure has the junction portion of the collection groove positioned on the side axially opposite the wheel flange. The inventors have determined that such a configuration increases the mechanical strength of the lining by minimizing the formation of stress concentrations on it. Furthermore, this solution allows for a groove size sufficient to ensure satisfactory particle collection efficiency. This configuration is counterintuitive to those skilled in the art, since it exposes the groove more to harsh conditions such as rain, mud, and sand than in a configuration where the groove is on the inner side, protected by the wheel flange.

[0010] The features described in the following paragraphs may optionally be implemented independently of each other or in combination with each other:

[0011] According to an improvement, the front portion and the rear portion of the collection groove each extend from an outer end near the outer edge of the trim to an inner end near the inner edge of the trim, said joining portion fluidly connecting the outer end of the front portion to the outer end of the rear portion.

[0012] According to an improvement, the inner ends of the front portion and the rear portion are located at least 10mm from the inner edge of the trim.

[0013] According to an improvement, the front portion and / or the rear portion opens onto the inner edge.

[0014] According to an improvement, the front portion and / or the rear portion extend(s) towards the inner edge parallel to the axial direction.

[0015] According to an improvement, the front portion and / or the rear portion extend(s) towards the inner edge, forming an angle of less than 15° with it, preferably tangentially to it.

[0016] According to an improvement, the junction portion is confined to an area at least 5mm away from the outer edge of the trim and extending to within 75mm of the outer edge of the trim.

[0017] According to an improvement, the collection groove, at the level of the fluidic link between the junction portion and one and / or the other of the front and rear portions, forms a radius of curvature R of at least 5mm.

[0018] According to an improvement, the sole comprises two lining supports connected by a link, the at least one lining comprising two portions of linings spaced apart from each other and each fixed respectively to one of the two supports of the sole.

[0019] According to an improvement, the front portion, the rear portion and the junction portion of the collection groove are open on the friction face.

[0020] According to an improvement, the front portion and the rear portion of the collection groove are substantially straight.

[0021] According to an improvement, the front portion and the rear portion of the collection groove are substantially curvilinear.

[0022] According to an improvement, the junction portion of the collection groove is substantially straight.

[0023] According to an improvement, the collection groove comprises a central portion open on the friction face, and extending in a central area of ​​the friction face, from an outer end near the outer edge to a inner end near the inner edge of the trim, the junction portion fluidly connecting the front portion, the rear portion, and the central portion of the collection groove. Brief description of the drawings

[0024] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0025] [Fig-1] shows a schematic representation of a braking assembly according to a for example, including a wheel and a brake pad mounted on a TBU

[0026] [Fig.2] shows a schematic side view of a braking assembly according to a example.

[0027] [Fig.3] shows two perspective views A and B of a fitting provided with a groove for example.

[0028] [Fig.4] shows a schematic representation of the forces as modeled for obtain the results shown in the following figure.

[0029] [Fig.5] shows a representation of the model results according to the assumptions of [Fig.4], on which it is possible to see the stress levels resulting from different groove profiles on an example of a trim.

[0030] [Fig. 6] shows five views A, B, C, D and E, each illustrating an example of a profile of groove, viewed along a radial direction, according to this disclosure.

[0031] [Fig.7] shows a perspective view of an example of a plate whose sole presents a connection between two supports, each of which carries a portion of the filling.

[0032] [Fig.8] shows a perspective view of the plate of [Fig.7], on which Each portion of the filling has a groove, as shown in the example.

[0033] [Fig.9] shows a cross-sectional view along an axial plane of a braking assembly according to an example, which highlights another beneficial effect of a braking system according to this disclosure. Description of the implementation methods

[0034] The drawings and description below contain, essentially, elements of a definite nature. They may therefore not only serve to better understand this disclosure, but also contribute to its definition, if necessary.

[0035] In the various figures, the same reference numerals designate identical or similar elements. For the sake of brevity, only the elements that are useful for understanding the described embodiment are shown in the figures and are described in detail below.

[0036] In the following description, when referring to absolute positional qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative positional qualifiers, such as the terms "above", "below", "superior", When using terms like "lower," "lower," etc., or orientation qualifiers such as "horizontal," "vertical," etc., reference is made, unless otherwise specified, to the orientation of the figures or that of a vehicle in its normal operating position. Furthermore, the term "approximately" should be interpreted as indicating that the result obtained is as precise as the known method for measuring it.

[0037] Fig. 1 shows an example of an assembly for braking a vehicle, in particular a railway vehicle (train, tram, metro, etc.) not shown. The assembly comprises a rotating element and a brake pad 1.

[0038] The rotating element corresponds to a part of the vehicle that causes translational movements of the latter by means of a rotational movement of this element around an axis of rotation. In this case, the rotating element is a wheel 10 of the vehicle configured to rotate around an axis of rotation A.

[0039] Advantageously, a radially external surface, otherwise called the tread 11 of the wheel 10, has a substantially frustoconical shape. The tread 11 can cooperate with, and more specifically be radially in contact with, a rail (not shown). Its frustoconical shape is particularly visible in [Fig. 2], by way of example. In particular, the diameter of the wheel 10 gradually increases between an axially external face, on the side of a flange 12 of the wheel, and an axially internal face, on the side of a flange 13 of the wheel 10.

[0040] The vehicle typically includes a second wheel (not shown), opposite wheel 10 and located on the opposite side of the vehicle. Wheel 10 and the second wheel may, for example, be mounted on the same axle. In this application, the terms "externally" / "outside" / "external" and "internally" / "internal" / "internal" express a meaning in the axial direction of the wheel in relation to the second wheel of the vehicle: the inside pointing towards the second wheel, and the outside in the opposite direction, outside the volume occupied by the vehicle.

[0041] In the present text, the axial direction corresponds to any direction substantially parallel to the axis of rotation A, and the radial direction corresponds to any direction substantially perpendicular to the axis of rotation A. The tangential or circumferential direction is perpendicular to the axial and radial directions.

[0042] Such a truncated conical shape of the tread 11 makes it possible to guarantee the self-centering of the wheel 10 during the translation of the vehicle, and limits the risk of derailment of the latter in the curves present on its path.

[0043] As can be seen in Figures 1 and 2, the flange 13 projects radially from the axially inner face of the wheel 10. Such a flange 13 also reduces the risk of derailment of the vehicle. On the axially opposite side, the flank 12 of the wheel 10 defines an axially outer side of the wheel 10.

[0044] Thus, according to the axial direction, the tread 11 is delimited externally by the wheel sidewall 12 and internally by the flange 13.

[0045] The assembly comprises a brake pad 1, also called a "shoe" or "brake shoe". The pad 1 includes a friction material 3. The friction material 3 includes a first face, called the friction face 31, arranged radially opposite the tread 11 of the wheel. The friction face 31 may be substantially curved, in a manner substantially complementary to the surface of the tread 11, and adapted to conform to the frustoconical shape of the tread 11. Depending on the case, such a conformation is obtained by wear of the friction material 3 on the tread 11 after a break-in period.

[0046] The lining 3 comprises a second face, called the fastening face 32, opposite the friction face 31. In particular, the friction face 31 and the fastening face 32 are opposite in the radial direction. Radially, the fastening surface 32 is farther from the tread 11 than the friction face 31.

[0047] The trim 3 further comprises an outer edge 33, an inner edge 34, a rear edge 35, and a front edge 36. The edges 33, 34, 35 and 36 extend substantially radially between the friction faces 31 and the fixing faces 32.

[0048] The tread is defined above as being axially delimited internally by the flange 13, and externally by the wheel sidewall 12. This convention is retained to define the edges of the lining. Thus, the lining 3 of the assembly according to the present disclosure is positioned so that the inner edge 34 of the lining is located near the flange 13, and the outer edge 33 is located near the wheel sidewall 12. Such a configuration is particularly visible in [Fig. 2].

[0049] The expression "near" the sausage 13 is to be understood as meaning that the edge in question is closer to the sausage 13 than to the flank 12. In the same way, "near" the flank 12 means that the edge in question is closer to the flank 12 than to the sausage 13.

[0050] The inner edge 34 and the outer edge 33 are therefore opposite along the axial direction. These edges 33, 34 connect the front edge 36 and the rear edge 35 to each other.

[0051] As is the case in particular in the example of [Fig.2], the inner edge 34 is axially opposite the flange 13 when the pad 1 is in contact with the wheel 10. Furthermore, a chamfer 37 at the junction between the inner edge 34 and the friction face 31 can allow the pad to conform easily with a joining surface 14 (connecting fillet) between the flange 13 and the tread 11.

[0052] The front edge 36 and the rear edge 35 are defined with respect to a direction of rotation of the wheel 10. In the example of [Fig. 1], it is assumed that the wheel 10 rotates in a direction R around the axis A. The front edge 36 corresponds to the edge of the trim 3 which is seen first by a specific point P imagined on the wheel 10 when it rotates around its axis of rotation A in the direction R, while the rear edge 35 corresponds to the edge of the lining 3 which is seen last by the specific point P when the wheel 10 rotates around its axis of rotation A in the direction R. Of course, taking into account that the railway vehicle may be required to move in both directions of rail traffic, the direction of rotation R could be opposite to that marked on [Fig.1], which would reverse the position of the front edge 36 and rear edge 35.

[0053] As will be detailed later, the trim 3 includes at least one particle collection groove 4.

[0054] The brake assembly may further include a base plate 2, visible in particular in Figures 2, 8 and 9. The base plate 2 may include a sheet metal plate, for example made of metallic material. The base plate 2 may accommodate, directly or indirectly, the mounting face(s) 32 of one or more lining(s) 3.

[0055] During braking, the assembly is configured to move the lining 3 in a direction that brings it closer to the wheel 10 until the friction face 31 and the tread 11 of the wheel 10 come into contact, as shown in [Fig. 9]. To this end, the assembly may include a shoe holder 7 supporting the shoe 2 which holds the lining 3, and actuating means for moving the shoe holder 7 substantially radially with respect to the wheel 10.

[0056] Once the braking phase is complete, the brake assembly is configured to move the brake pad 1 away from the wheel 10, so that contact between the friction face 31 and the tread 11 of the wheel 10 ceases. Indeed, outside of braking phases, the brake pad 1 and the wheel 10 are at a distance from each other, as illustrated in Figures 1 and 2.

[0057] When the friction face 31 of the brake pad 1 and the tread 11 of the wheel 10 come into contact during braking, the wheel 10 is rotating about axis A. A friction force is thus generated between the friction face 31 and the tread 11, causing wear on both the lining 3 of the brake pad 1 and the tread 11 of the wheel 10. Particles, usually pollutants, are thus formed by the abrasion of the friction material of the lining 3 and the wheel 10. During this wear, the friction face 31 of the lining 3 conforms to the shape of the tread 11 of the wheel 10.

[0058] As previously stated, the insert 3 includes at least one particle collection groove 4. In this text, for clarity, reference will be made to one groove, but it is possible to apply the described features to several grooves per insert without departing from the scope of this disclosure. By way of example, Figures 7 and 8 show an insert comprising two portions of fittings 3.1, 3.2, each having a collection groove 4. Such an example will be described below.

[0059] Said collection groove 4 is open at least partially on the friction face 31, as shown by way of example in Figures 3 and 6. The collection groove 4 extends in depth between the friction face 31 and the mounting face 32. The collection groove is preferably a blind groove at one end opposite its opening on the friction face 31. Typically, the groove 4 may have an opening on the friction face 31, but not on the mounting face 32. By "open at least partially" it should be understood that there may be portions of the groove 4 that do not open onto the friction face 31. These portions may eventually appear on the friction face 31 once the lining is worn.

[0060] The collection groove is shaped to recover the polluting particles resulting from the wear of the lining 3 and the wheel 10, and thus prevent these particles from being released into the environment.

[0061] Indeed, the collection groove 4 is in fluid communication with at least one conduit 5 formed in the lining 3 and opening onto any side of the lining other than the friction face 31. For example, the lining 3 may have a conduit 5 opening onto the outer edge 33 of the lining 3, as shown in the example in view B of [Fig. 3]. The groove 4 is also fluidly connected to at least one suction hole 6 capable of fluid communication with a source of vacuum (not shown). In this way, when the lining 3 is brought into contact with the tread 11 of the wheel, the latter obstructs the opening of the groove 4 leading to the friction face 31, and an airflow is then guided from the conduit 5, through the groove 4, to the suction hole 6 so as to collect the particles resulting from the abrasion of the friction material of the lining and / or the wheel.

[0062] Each suction hole 6 is intended to be connected to a vacuum source (not shown). The vacuum source is, for example, a particle vacuum cleaner. Communication means 8, an example of which can be seen in [Fig. 1], can connect the vacuum source to the corresponding suction hole 6. The particles collected in the collection groove 4 can thus be vacuumed and conveyed to a storage device, for example, one equipped with a filter (not shown). The communication means 8 include, for example, a flexible pneumatic hose.

[0063] As can be seen in [Fig.3], since the lining 3 tends to wear through the friction face 31, the suction holes 6 can advantageously be orifices located closer to the fixing face 32 than to the friction face 31, at the bottom of the groove, so that their operation is independent of the wear of the lining 3. For the same reason, the conduit 5 can also be located at the bottom of the groove 4.

[0064] Furthermore, the collection groove 4 has a front portion 41 extending at least partially near the front edge 36. The collection groove also includes a rear portion 42 extending at least partially near the rear edge 35 of the lining 3. The two front portions 41 and rear portions 42 are fluidly connected by a junction portion 43. The junction portion 43 is also formed in the material of the lining 2. In the same way as the front and rear portions, the junction portion 43, forming part of the groove 4, is also open on the friction face 31.

[0065] The junction portion 43 can be substantially straight and / or curved. To refer to its length, we speak of the so-called "circumferential" length, which allows us to refer to the circumferential direction along which this length is measured.

[0066] The expression "substantially straight" indicates that the trace of the portion of groove in question remains confined within a rectangular area whose shorter side does not exceed twice a width, measured transversely, of the groove.

[0067] The joining portion extends, for at least 50% of its circumferential length, near the outer edge 33 of the lining 3. Preferably, the joining portion extends near the outer edge 33 of the lining 3 along its entire circumferential length. Thus, when the lining 3 is mounted opposite the tread 11 of the wheel, the joining portion 43 of the collection groove is located near the sidewall 12 of the wheel, which externally delimits the tread 11 in an axial direction.

[0068] The term "near" is to be understood as meaning that the element in question is closer to the indicated edge or side than to the opposite side or edge. Thus, the joining portion, or at least 50% of its circumferential length, is closer to the outer edge 33 than to the inner edge 34. Preferably, the joining portion, or at least 50% of its circumferential length, is confined within an area formed by one-third, or even 20%, of the distance between the outer edge 33 and the inner edge 34. Optionally, the joining portion (or a part constituting at least 50% of its circumferential length) is confined within an area at least 5 mm from the outer edge of the trim and extending to within 75 mm of the outer edge.

[0069] Similarly, when the front portion 41 of the groove is said to be "near" the front edge 36 of the trim 3, it is understood that it is at least closer to the front edge 36 than to the rear edge 35. The same reasoning can be applied to the rear portion 42, which is then closer to the rear edge 35 than to the front edge 35.

[0070] Similarly, according to examples, the junction portion 43 can extend, over at least 50% of its circumferential length, at a distance from the outer edge 36 less than 20% of the distance which separates the outer edge 36 from the inner edge 35.

[0071] The inventors have determined that the position of this junction portion 43 can be critical to guarantee the mechanical strength of linings equipped with collection grooves 4. Indeed, the inventors were interested in the equivalent Von Mises stress values ​​on a lining when it is subjected to the forces of the braking action.

[0072] The forces considered in the model are illustrated in particular in [Fig. 4]. The model actually comprises two different load cases, each represented on one half of the lining. The first case considers a (resultant) force F applied to the friction face 31 in a radial direction, as well as a (friction) force M induced by a rotational moment about axis A applied in a tangential direction to the friction face 31 (which results from the rotation of the wheel 10 when it comes into contact with the lining). The second case considers a component T applied in an axial direction at the inner edge 34, in particular on the chamfer 37. Indeed, the wheel flange may exert a force on the sole when the vehicle is on a slope, typically when turning.

[0073] Figure 5 shows radial and isometric views of numerical simulations of Von Mises stresses for different groove configurations. The results given in Figure 5 show that, subjected to these stresses, a lining 3 having a groove 4 with a joining portion 43 near the inner edge 34 (left example) experiences a very high stress near the inner edge 34. The inventors therefore tested different groove profiles 4, concluding that, as illustrated in the middle and right examples, the best configuration is obtained when the groove 4 extends near the outer edge 33, i.e., axially opposite to the area on the side of the flange 13 of the wheel 10. The maximum stresses are significantly lower (at least twice as low) when the joining portion of the groove is near the outer edge.Such a configuration makes it possible both to maintain satisfactory particle collection efficiency and to guarantee sufficient mechanical strength of the linings, thus ensuring maximum service life.

[0074] Different groove profiles 4 enabling this configuration to be achieved will now be described.

[0075] According to examples, and in particular as illustrated in Figures 3 and 6, the front portion 41 extends from an outer end 41.1 near the outer edge 33 to an inner end 41.2 near the inner edge 34. Similarly, the rear portion 42 extends from an outer end 42.1 to an inner end 42.2. The connecting portion 43 fluidly links the front portion 41 and rear portion 42 by their outer ends 41.1 and 42.1.

[0076] According to examples, the front portion 41 and / or the rear portion 42 can open onto the inner edge 34, for example onto the chamfer 37. In this case, there is no material separating the groove 4 from the inner edge 34 and / or the chamfer 37.

[0077] According to examples, the front portion 41 and / or the rear portion 42 extend(s) through the chamfer 37, for example to the inner edge 34.

[0078] In other cases, the front portion 41 and / or the rear portion 42 do not extend through the chamfer 37 but stop before, this is the case in particular in figure 3a, so that material separates the groove from the chamfer 37.

[0079] According to examples, it is possible for the front portion 41 and rear portion 42 to extend to a distance from the front edge 36 and rear edge 35 respectively that is less than 20% of the distance between the front edge and the rear edge of the trim. In particular, the front portion 41 and rear portion 42 may extend to a distance from the front edge 36 and rear edge 35 respectively of between 10 and 15 mm.

[0080] According to examples, the inner ends 41.1, 42.1 of the front portion 41 and the rear portion 42 are located at least 10 mm from the inner edge 34 of the trim 3, so as to avoid forming excessively high stress concentrations at this edge.

[0081] Examples A to D of [Fig. 6] show that, according to certain configurations, the connecting portion 43 can fluidly connect the two outer ends 41.1 and 42.1 of the front portion 41 and rear portion 42 along the outer edge 33, for example, by remaining confined within the area described above, in particular an area extending to a distance less than or equal to 20 mm from the outer edge 33. The front and rear portions 41, 42 also extend along the front edge 35 and rear edge 36 of the trim, respectively. In some examples, the front and rear portions 41, 42 extend parallel to each other in an axial direction.

[0082] Thus, Figure 6A presents a “U” profile with a junction portion 43 substantially straight and parallel to the outer side 33, and front and rear portions straight and parallel respectively to the front and rear edges.

[0083] Figure 6B shows that the groove 4 may include a central portion 44. The profile is thus an "E". It extends in a central area of ​​the friction face 31, for example located approximately equidistant from the front edge 35 and the rear edge 36, and is open to the friction face in the same way as the other portions of the groove. This central portion 44 extends from an outer end 44.1 near the outer edge 33 to an inner end 44.2 near the inner edge 34 of the lining 3, and is also fluidly connected to the connecting portion 43. According to some examples, the front, central, and rear portions 41, 42, 44 extend parallel to each other in an axial direction. In a non-standard embodiment represented where the front and rear portions are not parallel to the front and rear edges, the profile can be a "W".

[0084] Figure 6C shows a variant of the configuration of Figure 6A, in which the front and rear portions 41, 42 form, at their inner ends 41.1, 42.1, a fluidic connection with the junction portion 43, which describes a radius of curvature R. Such a radius of curvature R can, for example, be between 5 and 50% of the distance separating the junction portion 43 from the opposite outer edge 34. The radius of curvature R can be between 1 mm and 25 mm, more particularly between 5 mm and 15 mm. It has been demonstrated by the inventors, in particular, during the tests described above, the results of which are shown in [Fig. 7], that such a radius of curvature R makes it possible to reduce stress concentrations at the outer ends 41.1, 42.1.

[0085] Figures 6A, 6B and 6C show examples in which the front and rear portions 41, 42, and central portion 44 where applicable, can extend, or even open out, at their outer end 41.2, 42.2, 44.2, in a substantially perpendicular manner to the outer edge 34, that is to say in a direction parallel to the axial direction.

[0086] In contrast, Figure 6D shows that the front and rear portions 41, 42 can alternatively extend, at their inner end 41.1, 42.1, substantially tangentially with the inner edge 34, or with the common edge between the chamfer 37 and the friction face 31. The expression "substantially tangential" here means that an angle of up to 15° with respect to the edge of the chamfer 37 is permitted. In this way, the groove forms a "C" profile. According to examples, the portions 41 and 42 are curved, and can in particular form two opposing semicircles.

[0087] Furthermore, according to an example illustrated in figure 6E, it is also possible that the front and rear portions 41, 42 extend, beyond a point of tangential contact with the inner edge 34, in a curve bringing their inner end 41.1, 42.1 closer to the joining portion 43. In this way, the portions 41 and 42 can be in two-thirds or three-quarters of circles.

[0088] Other profiles are possible, particularly when the joining portion connects an inner end of one of the front or rear portions with an outer end of the other front or rear portion. For example, an S-shaped or Z-shaped profile can be obtained. As long as a major part of the joining portion is located near the outer edge, the benefits to the durability of the insert are guaranteed.

[0089] On the other hand, it is possible that the front and rear portions 41, 42 have different profiles from each other.

[0090] Figures 7 and 8 show two isometric views of the pad in a configuration where the lining 3 consists of two parts. The pad has a base 2 with two lining supports 21, connected by a link 22 which may have some flexibility. The pad thus has two lining portions 3.1 and 3.2, each attached to a respective support 21. The link 22 may be located, for example, substantially in the middle of the base 2 and allows the two supports 21 to conform more easily and quickly to the shape of the tread 11. The two lining portions 3.1 and 3.2 may be part of a single, one-piece lining 3, and may have a portion thinned in its middle to give it sufficient flexibility to easily conform to the shape of the tread. In other examples, the two lining portions 3.1 and 3.2 are distinct and form two separate, one-piece linings.

[0091] Depending on the circumstances, each trim portion 3.1, 3.2 may have its own groove 4.1, 4.2. Each groove 4.1, 4.2 may then have a profile as described in this disclosure, for example, a "C", "E", "U", "W", "S", or "Z" profile on its respective trim portion. It is also possible that only one trim portion has a groove, or that the two trim portions have different groove profiles.

[0092] Figure 9 illustrates, by way of example, another beneficial technical effect obtained with a braking assembly according to the present disclosure. Indeed, in view A, the lining 3 is brought against the tread 11, and the chamfered edge 37 is adapted to conform to the shape of the surface junction 14 between the flange 13 and the tread 11. However, due to the frustoconical shape of the tread 11, the diameter of which gradually decreases as it approaches the side of the wheel rim 12, it is possible that the lining 3 may translate in an axial direction away from the flange 13 and towards the wheel rim 11. Consequently, if the groove has a portion located too close to the chamfered edge 37, it is possible that an air leak may result from the open space 20 between the chamfered edge 37 and the junction surface 14.The design of this disclosure therefore also has the advantage of ensuring good suction even during axial slippage of the pad.

[0093] The invention has been described in a non-limiting way in the context of railway rolling stock, but those skilled in the art will understand that the technical benefits obtained here are transferable to braking systems of motor vehicles or industrial machines.

Claims

Demands

1. Assembly for railway vehicle comprising: a wheel (10) defining an axial direction (A), and comprising a tread (11) delimited externally by a wheel sidewall (12) and internally by a flange (13);and a brake pad (1) comprising a backing plate (2) and at least one lining (3) made of a friction material, the at least one lining (3) being fixed to said backing plate (2) and being delimited by a friction face (31) configured to come into contact with the tread (11) of said wheel (10), a fixing face (32) on the backing plate (2), an inner edge (34), an outer edge (33), a rear edge (35) and a front edge (36), the at least one lining (3) further comprising a particle collection groove (4) open on the friction face (31), said collection groove (4) being in fluid communication with a conduit (5) opening out of the friction face (31) and with a suction hole (6) suitable for being connected to a vacuum source, said collection groove (4) comprising:; - a front portion (41) extending at least partly in close proximity respectively to the front edge (36); - a rear portion (42) extending at least partly near the rear edge (35) of said trim (3); and - a connecting portion (43) fluidly linking the front portion (41) and the rear portion (42), said connecting portion (43) having a circumferential length, the connecting portion (43) extending, over at least 50% of its circumferential length, near the outer edge (33) of said lining (3), the outer edge (33) being arranged axially closer to the wheel sidewall (12) than to the flange (13).

2. Assembly according to claim 1, wherein the front portion (41) and the rear portion (42) of the collection groove (4) each extend from an outer end (41.1, 42.1) near the outer edge (33) of the lining to an inner end (41.2, 42.2) near the inner edge (34) of the lining, said connecting portion (43) fluidly connecting the outer end (41.1) of the front portion (41) to the outer end (42.1) of the rear portion (42).

3. Assembly according to the preceding claim, wherein the inner ends (41.1, 42.1) of the front portion (41) and of the rear portion (42) are located at least 10mm from the inner edge (34) of the trim (3).

4. Assembly according to the preceding claim, wherein the front portion (41) and / or the rear portion (42) extend(s) towards the inner edge parallel to the axial direction.

5. Assembly according to claim 3, wherein the front portion (41) and / or the rear portion (42) extend(s) towards the inner edge (34) forming with it an angle of less than 15°, preferably tangentially to it.

6. Assembly according to any one of claims 1 to 5, wherein the joining portion (43) is confined in an area at least 5mm away from the outer edge (33) of the trim (3) and extending to within 75mm of the outer edge (33) of the trim (3).

7. Assembly according to any one of claims 1 to 6, wherein the collection groove (4), at the level of the fluidic link between the junction portion (43) and one and / or the other of the front portion (41) and the rear portion (42), forms a radius of curvature R of at least 5mm.

8. Assembly according to any one of claims 1 to 7, wherein the sole (2) comprises two supports (21) of lining connected by a link (22), the at least one lining (3) comprising two portions of linings (3.1, 3.2) spaced apart and each fixed respectively to one of the two supports (21) of the sole (2).

9. Assembly according to any one of claims 1 to 8 wherein the front portion (41), the rear portion (42) and the joining portion (43) of the collection groove (4) are open on the friction face (31).

10. Assembly according to any one of claims 1 to 4 or 6 to 9, wherein the front portion (41) and the rear portion (42) of the collection groove (4) are substantially straight.

11. Assembly according to any one of claims 1 to 9, wherein the front portion (41) and the rear portion (42) of the collection groove (4) are substantially curvilinear.

12. Assembly according to any one of claims 1 to 11, wherein the joining portion (43) of the collection groove (4) is substantially straight.

13. Assembly according to any one of claims 1 to 12, wherein the collection groove (4) comprises an open central portion (44) on the friction face (31), and extending in a central area of ​​the friction face (21), from an outer end (44.1) near the outer edge (33) to an inner end (44.2) near the inner edge (34) of the lining (3), the joining portion (43) fluidly connecting the front portion (41), the rear portion (42), and the central portion (44) of the collection groove (4).

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