Disk brake pad with obliquely extending collection groove

The brake pad for a disk brake includes a lining and a plate. The lining includes:—a friction face and a fastening face;—a rear edge;—an inner edge and an outer edge; and—a collection groove extending into the inner edge or outer edge. The plate has a hole, the hole being connected to a vacuum source via communication element. The lining has a rear region including the rear edge and the collection groove, and a chamfered portion such that an area of a friction surface of the rear region increases when a thickness of the rear region decreases, the collection groove being located at a distance from a free surface of the chamfered portion and having a cross-section which extends obliquely towards the free surface of the chamfered portion.

FIELD OF THE INVENTION

The present invention relates to vehicles, in particular automobiles and also railway rolling stock. More specifically, the invention relates to the braking of vehicles and railway rolling stock. The invention further relates to brake pads for disk brake assemblies for said vehicles and said railway rolling stock.

It will be noted that according to the invention, the vehicle may be of any type and may in particular be a car, a lorry or a bus. Similarly, the railway rolling stock may be a train, a tramway or even a tube railway.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

A vehicle or a railway rolling stock generally comprises a braking system. The braking system may in particular be a disk brake system. The braking system then includes a disk integral with a wheel or with an axle of the vehicle or of the railway rolling stock. Thus, when the wheel, or the axle, starts to rotate to make it possible for the vehicle or the railway rolling stock to move, the disk also starts to rotate.

Thus, in order to brake the vehicle or the railway rolling stock, the disk brake system comprises friction means of the disk. The friction means include in particular two plates that each support a lining that comprises a friction material. The friction material is configured to come into contact with the disk. The two plates supporting the friction linings are disposed on either side of the disk so as to squeeze same when the brake system is actuated.

However, when the friction material comes into contact with the disk while said latter is in rotation, the friction material emits particles that are harmful for the environment. Braking systems are therefore pollutants.

This is why, it is known to arrange a device for extracting the particles originating from the braking in the braking system. The extraction device is intended to extract the particles from the braking not long after the emission of said latter.

Nevertheless, the extraction device is mainly adapted to operate when the brake pad is in an “ex-works” configuration. Thus, during the use thereof, the extraction of the braking particles may be less effective.

AIM OF THE INVENTION

One aim of the invention is to provide a brake pad for a disk brake assembly whereof the performances remain constant, or even are improved or at least deteriorate little, over time.

BRIEF SUMMARY OF THE INVENTION

For this, it is provided according to the invention a brake pad for a disk brake assembly, comprising a lining made of friction material and a plate supporting the lining, wherein:the lining comprises:a friction face and a fastening face,a rear edge, located on the side where the disk is capable of coming out of an interface with the pad when the disk rotates in a direction of advance of the vehicle, and a front edge,an inner edge and an outer edge, anda collection groove open on the friction face and arranged close to the rear edge, the collection groove leading into the inner edge or outer edge,the plate includes a hole in fluid communication with the collection groove, the hole being connected to a vacuum source via communication means,

characterised in that the lining includes a rear region comprising the rear edge and the collection groove, the rear region including a chamfered portion such that an area of a friction surface of the rear region increases when a thickness of the rear region decreases, the collection groove being arranged at a distance from a free surface of the chamfered portion and comprising a cross-section which extends obliquely towards the free surface of the chamfered portion.

Thus, as the brake pad wears during the use thereof, the area of the friction surface of the rear region that is disposed between the collection groove and the rear edge of the lining increases. Therefore, braking particles will be emitted rearwards of the vehicle and this, downstream of the collection groove. However, as the cross-section of the collection groove extends obliquely towards the free surface of the chamfered portion, a distance between said free surface and the collection groove increases less, or even remains identical, than if the cross-section of the collection groove extended perpendicular to a plane including the fastening face of the lining. The effectiveness of the collection of braking particles is therefore maintained or slightly impaired, or even improved during the use of the brake pad.

Furthermore, the chamfered portion disposed in the rear region makes it possible to provide a less abrupt contact between the lining and the disk. Thus, the brake pad has better acoustic performances, the noise during the braking being reduced.

In addition, the chamfered portion forms a ramp for the evacuation of water, for example due to rain or originating from thawed frost.

Moreover, it will be noted that “friction surface” means the portion of the friction surface of the lining that is capable of effectively coming into contact with the disk during the braking.

Furthermore, in various embodiments of the invention, one and/or other of the following layouts may also be used:the cross-section of the groove forms an angle with a straight line normal to the fastening face between 20° and 80° or between 30° and 60° or preferably between 40° and 50°;the cross-section of the groove extends substantially parallel to a section of the free surface of the chamfered portion;a distance between the collection groove and the free surface of the chamfered portion is constant along the collection groove;the lining includes a rear region including the rear edge, the rear region further comprising a chamfered portion such that an area of a friction surface of the rear region increases when a thickness of the rear region decreases;an area of the chamfered portion of the front region and an area of the chamfered portion of the rear region are substantially equal;the chamfered portions of the rear region and front region are flat, an angle formed between the chamfered portion of the rear region and a plane comprising the fastening face is substantially equal to an angle formed between the chamfered portion of the rear region and the plane comprising the fastening face;the collection groove is hollowed out directly in the friction material, up to the surface of the plate;the collection groove extends between an open end and a blind end, the hole of the plate leading into the groove close to the blind end.

Furthermore, it is also provided according to the invention a disk brake assembly including a disk and two brake pads such as described above and disposed on either side of the disk.

Finally, it is provided according to the invention a disk brake system that comprises a disk brake assembly such as described above and wherein the disk is integral with an axle or with a wheel.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

It will be noted that in the interest of clarity, only the elements useful for understanding the embodiments described have been shown and will be described in detail.

Furthermore, unless otherwise specified, the expressions “substantially”, “approximately”, etc., mean that only a minor variation in relation to the nominal value considered is possible, in particular a low percentage, particularly at about 10%.

It is shown inFIGS. 1 and 2a disk brake system19according to the invention for a vehicle. In this embodiment, the vehicle is a motor vehicle, in the present case a light vehicle. Nevertheless, it will be noted that the invention may be implemented for any type of vehicle, such as a tractor for semi-trailer, a bus or an agricultural tractor, or for any type of railway rolling stock, such as locomotive or a carriage.

The disk brake system19according to the invention includes a disk9, of axis A integral with a wheel of the vehicle. The disk9has a lateral face9A and an opposite lateral face9B. The lateral faces9A,9B are perpendicular to the axis A. The disk9is also connected to a drive mechanism, via in particular a hub, same connected to a motor of the vehicle. Thus, the drive mechanism makes it possible to transmit to the wheel of the vehicle, via the disk9, a rotational movement about the axis A and this, in order to move the vehicle.

Furthermore, the disk brake system19includes a calliper5that holds tightly, so as to sandwich, a portion of the disk9. As illustrated in particular inFIG. 2, the calliper5is in the form of a main body50that is generally U-shaped so as to hold tightly the disk9. Furthermore, the main body50includes a cavity for accommodating a piston55. The calliper5also includes two fingers51,52. The piston55is capable of exerting a force PF in a direction A2identified inFIG. 1and that is parallel to the axis A of the disk.

InFIG. 1, it is shown a direction of rotation FW of the disk9that corresponds to a forward motion of the vehicle. It is also shown a tangential direction T on a circumference of the disk9.

It is also defined a rear side and an opposite front side. The rear side corresponds to the side where the disk9comes out of the interface with the calliper5when the disk9rotates in the direction of advance of the vehicle. The front side is the opposite side and corresponds to the side where the disk9enters into the interface with the calliper5when the disk9rotates in the direction of advance of the vehicle. In addition, it is defined for a radial direction going from the axis A to the circumference of the disk9, a direction that goes from the inside to the outside.

The disk brake system19comprises a calliper bracket6that is fastened to a component of the vehicle. Said component may in particular be a control arm of the vehicle. Furthermore, the calliper bracket6comprises two retainer clips61,62disposed at two rear and front longitudinal ends of the calliper5and a connection arch63that connects the two retainer clips61,62. The retainer clip61is rear retainer clip and the retainer clip62is a front retainer clip.

The disk brake system19also includes two brake pads10A,10B accommodated in the calliper5. The two brake pads10A,10B are disposed on either side of the disk9. The brake pad10A is disposed opposite the lateral face9A of the disk9. The brake pad10B is disposed opposite the lateral face9B of the disk9. Thus, the two brake pads10A,10B are disposed symmetrically in relation to a plane including the disk9and perpendicular to the axis A of the disk9.

The piston55of the calliper5is arranged to exert the force PF on the brake pad10A such that the two pads10A,10B come into contact with the disk9so as to brake the vehicle when the disk brake system19is actuated by a driver of the vehicle. It is noted that in the example illustrated, the calliper5is mounted “floating” in the calliper bracket6, along the axis A. Thus, the calliper5may move parallel to the axis A in particular to compensate the progressive wear of the pads10A,10B. On the other hand, the calliper5is maintained integral with the calliper bracket6according to the other potential translations and rotations. The float mounting is usually produced thanks to guide pins sliding along the axis A.

It will now be described in greater detail, the brake pad10A. By taking into account effects of symmetry, the following description is also valid for the brake pad10B.

The pad10A is in particular illustrated inFIGS. 3 and 4. Thus, the brake pad10A comprises a plate20that supports a friction lining22. The plate20is in the form of a solid metal plate and of substantially constant thickness. The plate20includes a rear arm24and a front arm26that make it possible to fasten the plate20to the main body55of the calliper5by means of hooks28. The plate20includes a fastening face to which is fastened the friction lining22. The face opposite the fastening face is fastened to the piston55as illustrated inFIG. 2.

The friction lining22is in the form of a body made of friction material capable of coming into contact with the lateral face9A of the disk9in order to brake the vehicle. The friction material is sometimes called “ferodo”. The friction lining22therefore includes a friction face30intended to come into direct contact with the lateral face9of the disk9. The friction lining22also includes a fastening face32, opposite the friction face30, and fastened directly to the fastening face of the plate20. In addition, with reference to the sides previously defined, the friction lining22includes a rear edge34and an opposite front edge36. The friction lining22also includes an inner edge38and an outer edge39.

When the disk brake system19is actuated, the contact between the friction face30of the friction lining22of the brake pad10A and the lateral face9A of the disk9generates the emission of polluting braking particles. Said braking particles correspond to particles of the friction material that detach from the friction lining22due to abrasion with the lateral face9A of the disk9as well as to particles that detach from the disk9. This is why, the disk brake system19includes braking particle extraction means described below.

The friction lining22includes a collection groove3. The collection groove3is open on the friction face30and is arranged close to the rear edge34of the friction lining22. Thus, during forward motion of the vehicle, the braking particles are carried towards the collection groove3, which makes it possible to improve the effectiveness of the collection. When the vehicle is braked while it is in forward motion, the braking particles are emitted towards the front FW, with reference to the forward motion of the vehicle. Thus, the capture of braking particles is all the more effective as the collection groove3is disposed close to a rear border of a portion of the friction face30that is directly in contact with the lateral face9A of the disk9.

As shown inFIG. 2, the collection groove3is single, straight and continuous. Same is of constant width. Furthermore, the collection groove3is directly hollowed out in the friction material and this, up to the plate20.

The collection groove3further extends between an open end31and a blind end33. The open end31is disposed on the inner edge38of the friction lining22. The blind end33is disposed close to the outer edge39. Of course, the open end31may also be disposed on the outer edge39of the friction lining22. The blind end33may also be disposed on the inner edge38of the friction lining22.

The plate20includes a hole17that leads into the collection groove3. The hole17is substantially opposite the blind end33. The hole17may more generally be disposed close to the blind end33. The hole17is also in pneumatic communication with the collection groove3.

In addition, as illustrated inFIG. 2, the disk brake system19includes an extraction device8in pneumatic communication with the hole17by means of a hose40that passes through the main body50of the calliper5. The extraction device8includes a vacuum source, for example a turbine, and a filter for filtering the air extracted and loaded with braking particles. The vacuum source is configured to extract from the collection groove3.

Thus, the hole17is connected to a vacuum source via communication means that here include the hose40.

In addition, the friction lining22includes a rear region60and a front region62. The rear region60includes the rear edge34of the friction lining22and the collection groove3. The front region62includes the front edge36. The rear region60and the front region62are disposed one after the other and are in contact. Same each substantially occupy one half of the friction lining22. It is shown inFIG. 4, an axis M that delimits the border between the rear region60and the front region62.

The rear region60includes a friction surface60A that is a surface capable of coming directly into contact with the lateral face9A of the disk9when the brake system19is actuated. Similarly, the front region62includes a friction surface62A that is a surface capable of coming directly into contact with the lateral face9A of the disk9when the brake system19is actuated.

The rear region60includes a chamfered portion64that connects the friction surface60A of the rear region60and the rear edge34of the friction lining22such that a thickness of friction lining22is greater at a portion that includes the friction surface60A than at a portion that comprises the rear edge34. Thus, when the thickness of the rear region60decreases, in particular due to the wear caused by the use of the brake pad10A, an area of the friction surface60A of the rear region60increases.

Similarly, the front region62includes a chamfered portion66that connects the friction surface62A of the front region62and the front edge36of the friction lining22such that a thickness of friction lining22is greater at a portion that includes the friction surface62A than at a portion that comprises the front edge36. Thus, when the thickness of the front region62decreases, in particular due to the wear caused by the use of the brake pad10A, an area of the friction surface62A of the front region62increases.

Therefore, it is understood, in particular usingFIG. 3, that the chamfered portions64,66respectively of the rear region60and of the front region62are not respectively part of the friction surfaces60A,62A of the rear region60and front region62.

It will be noted that in the present embodiment, an area of the free surface of the chamfered portion64of the rear region60and an area of a free surface of the chamfered portion66of the front region62are substantially equal. Thus, in “ex-works” configuration, the area of the friction surface60A of the rear region60is substantially equal to the area of the friction surface62A of the front region62.

According to variants, said two areas may differ. In particular, the area of the free surface of the chamfered portion66of the front region62may be greater than the area of the free surface of the chamfered portion64of the rear region60. Thus, during the use of the brake pad10A, the area of the friction surface62A of the front region62will tend to become greater than the area of the friction surface60A of the rear region60. Therefore, when the brake system19is actuated while the vehicle is in forward motion, more braking particles will be emitted upstream of the collection groove3and this towards the collection groove3. The effectiveness of the capture of braking particles is therefore maintained over time, the effect indicated above compensating the effect of the wear of the braking system19.

In addition, as illustrated inFIG. 4in particular, the chamfered portions64,66are flat. The free surface of the chamfered portion64thus forms, with a plane that includes the fastening surface32of the friction lining22, an angle that is substantially equal to an angle formed between the free surface of the chamfered portion66and the plane that includes the fastening surface32.

Furthermore, the chamfered portions64,66respectively of the rear region60and front region62also have the property of making possible a less abrupt contact between the lateral face9A of the disk9and the friction lining22when the braking system19is actuated. Thus, the noise and the vibrations generated during braking are decreased. Furthermore, the chamfered portions64,66form ramps to evacuate water, for example coming from rain.

In addition, as can be observed inFIG. 3, the chamfered portion64of the rear region60includes an inner border64A and an outer border64B that are respectively partially combined with the lower edge38and outer edge39of the friction lining22. The inner border64A has a length relatively shorter than the outer border64B.

Similarly, the chamfered portion66of the rear region62includes an inner border66A and an outer border66B that are respectively partially combined with the lower edge38and outer edge39of the friction lining22. The inner border66A has a length relatively shorter than the outer border66B.

In addition, as can be seen inFIGS. 3 and 4, the collection groove3is arranged at a distance from the free surface of the chamfered portion64of the rear region60. The collection groove3is disposed at a distance from the free surface of the chamfered portion64that is substantially constant along the collection groove3.

Furthermore, as illustrated inFIG. 4, according to a cross-section, the collection groove3extends, from the friction face30up to the fastening face of the plate20, obliquely towards the free surface of the chamfered portion64.

According to the present embodiment, the cross-section of the collection groove3extends substantially parallel to the free surface of the chamfered portion64. Thus, a distance between the collection groove3and the free surface of the chamfered portion is constant even when the friction lining22has a certain wear as can be seen by comparingFIGS. 4 and 5. Indeed, it is shown in dotted lines inFIG. 5a portion of the friction lining22that disappeared following the wear of the friction lining22.

The effectiveness of the capture of the braking particles is therefore preserved despite the wear of the friction lining22.

In addition, it is shown inFIG. 4an angle D1corresponding to an angle formed between the cross-section of the collection groove3and a straight line L perpendicular to the fastening face32of the friction lining22. Here, the angle D1is substantially equal to 45°. The angle D1is more specifically defined between an axis W1of the collection groove3and the axis L.

According to variants, the angle D1is between 20° and 80° or between 30° and 60° or between 40° and 50°.

It is also shown inFIG. 4an angle D2corresponding to an angle formed between a straight line W2supported by the free surface of the chamfered portion64and the straight line L. In the embodiment illustrated inFIG. 4, D1and D2are equal.

However, more generally, D1is strictly greater at 0° and is less than or equal to D2. According to one variant, D1is strictly greater than D2.

Similarly, an angle formed between the free surface of the chamfered portion64of the rear region60with a plane that comprises the fastening face32of the friction lining22, and that is therefore normal to the straight line L, is substantially identical to an angle formed between the free surface of the chamfered portion66of the front region62and said plane comprising the fastening face32of the friction lining22.

It is shown inFIG. 6a variant of the embodiment described above. Only the differences will be indicated.

According to the variant inFIG. 6, the cross-section of the collection groove3does not extend substantially parallel to the free surface of the chamfered portion.

Of course, many changes may be made to the invention without departing from the scope thereof.

The angle D1may also be between 60° and 80° and in particular be substantially equal to 70.

In particular, any type of vacuum source or more generally extraction means may be used.

Also, any type of material may be used for the friction lining22.