Braking system with air blowing in the groove in the lining

Disclosed is a braking system including a brake pad with a backing plate having first and second faces, and a lining made of friction material on the first face. The lining having friction and mounting faces, and inner, outer, rear and front edges. The lining has a collection groove open to the friction face, and an opening at its first end towards the inner edge and an opening at its second end towards the outer edge. The braking system further includes a suction system with suction and blow pipes through which air is sucked in and a blown. The air inlet orifice of the suction pipe is opposite one end of the groove, and the air outlet orifice of the blow pipe is opposite the other end of the groove.

This application is the U.S. national phase of International Application No. PCT/EP2020/058815 filed Mar. 27, 2020 which designated the U.S. and claims priority to FR Patent Application No. 1903216 filed Mar. 28, 2019, the entire contents of each of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to non-polluting braking systems, intended for use in machines comprising a rotating element whose rotation is to be slowed down, for example such as road or railway vehicles, or wind turbines.

Description of the Related Art

In such braking systems, particles and dust are emitted by friction braking, as a result of abrasion of the brake pads against the rotating element. This rotating element is for example the wheel of the vehicle, or a disc driven by the wheel of the vehicle. It is known that these particles dispersed into the ambient environment are harmful to an individual's health. In addition, the growth of electric motors for motor vehicles has reinforced the need to treat the particles and dust resulting from the abrasion of friction braking systems. There is therefore a need to capture these particles and dust before they are released into the ambient environment.

Thus, there is the known document FR 3,057,040 which describes a braking system comprising a brake pad10, this pad comprising a backing plate1with a first face13and a second face14, and a lining2made of friction material and fixed to the first face13, the lining2being delimited by a friction face26, a mounting face20, an inner edge23, an outer edge24, a rear edge21, and a front edge22. The lining2is provided with at least one collection groove3which is open to the friction face26, and which has an opening at its first end towards the inner edge23and has an opening at its second end31towards the outer edge24. The backing plate1comprises a hole17in fluid communication with the collection groove3. The hole17is connected to a suction system by a suction pipe40capable of sucking in the air and the particles and dust flowing in the groove3.

Such a braking system is illustrated inFIGS.10and11, and represents the prior art.

However, this braking system has disadvantages.

In fact, particles and dust continue to escape in undesirable amounts during the braking phases.

SUMMARY OF THE INVENTION

The invention aims to remedy these disadvantages.

The invention aims to provide a braking system for which the capture of particles and dust emitted by the lining and rotating element is optimized, and for which the construction is as simple as possible.

This object is achieved by virtue of the fact that the braking system further comprises a suction system which comprises a suction pipe through which air is able to be sucked in, and a blow pipe through which air is able to be blown, the air inlet orifice of the suction pipe being located opposite one end of the at least one groove, selected among the first end and the second end, and the air outlet orifice of the blow pipe being located opposite the other end of the groove, selected among the first end and the second end.

Due to these arrangements, the collection of particles and dust by the suction system is more efficient, since the simultaneous blowing and suctioning of air makes it possible to guide the particles and dust towards the suction pipe. The release of these particles and dust into the atmosphere is therefore minimized.

Advantageously, neither the suction pipe nor the blow pipe are in contact with the lining or the backing plate.

There is thus no generation, after the braking phase, of a more or less significant residual torque when the linings and pads move away from the rotating element.

For example, the air inlet orifice of the suction pipe is located opposite the second end, and the air outlet orifice of the blow pipe is located opposite the first end.

Thus, air flows in the groove from the inner edge to the outer edge of the lining. Since this direction is the natural direction (without suction/blowing) of the air flow in the groove under the effect of centrifugal force, the collection of particles and dust in the suction pipe is more efficient.

Advantageously, the first end opens onto the inner edge.

Air thus escapes from the groove (towards the suction pipe) in the extension of the groove, which makes the suction more efficient. In addition, since the suction pipe is located in the main plane of the lining, it is not necessary to modify the caliper to integrate this pipe into the structure of the braking system.

Advantageously, the air inlet orifice of the suction pipe is located opposite the first end, and the air outlet orifice of the blow pipe is located opposite the second end.

Air thus flows in the groove from the outer edge to the inner edge of the lining.

Advantageously, the second end opens onto the outer edge.

Air thus escapes from the groove (towards the suction pipe) in the extension of the groove, which makes the suction more efficient. In addition, since the suction pipe is located in the main plane of the lining, it is not necessary to modify the caliper to integrate this pipe into the structure of the braking system.

Advantageously, the suction system comprises a pump and a filter, the pump, the filter, the suction pipe, and the blow pipe forming a continuous circuit.

The suction system is thus simplified. In addition, the air filtered by the filter is reused for blowing into the groove, causing particles (which have not already been captured by the filter) to pass through the filter several times. The probability that particles will be stored in this filter is therefore increased.

Advantageously, the at least one groove is located near the rear edge.

The capture of particles and dust by the groove is thus optimized, these particles and dust having a tendency to flow from the front to the rear of the lining, since this direction of flow is the direction of movement of the rotating element relative to the lining at rest.

Advantageously, the lining is provided with a second groove which is located substantially midway between the front edge and the rear edge.

The vibrational behavior of the lining-disc assembly during braking is thus improved.

Advantageously, the lining is provided with an additional groove which is located near the front edge.

The system according to the invention thus operates equally efficiently in both directions of rotation of the rotating element relative to the lining, which is advantageous for vehicles which must brake in both directions, such as railway vehicles.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention relates to a braking system which comprises a brake pad10of a brake intended for braking a rotating element9of a machine. The invention is described below in the case where the machine is a road vehicle in which this brake is a disc brake. However, the invention applies equally well to the case of a brake pad in a shoe brake which rubs on a wheel, used in vehicles on rails (railway vehicles), or to the case of a brake pad used in any other industrial machine (for example in the case of a wind turbine). In all cases, the braking of a rotating element of the machine is achieved by friction of the brake pad on this rotating element during its rotation.

In a disc brake, the braking is achieved by friction between a disc (which is the rotating element9) which is integral with a wheel of the vehicle, and two brake pads10which press against this disc9one on each side in order to sandwich it. The disc9extends in a main plane and has as its axis of rotation an axis A which is perpendicular to this main plane.

Each of the pads10extends in this main plane, such that the thickness of a pad10extends along the axis of rotation A.

The disc9rotates about the axis of rotation A with a direction of rotation FW, which defines a tangential direction T which is tangent to the circumference of the disc9and oriented in the direction of rotation FW, and a radial direction R orthogonal to the axis of rotation A in the main plane of the disc9.

These elements are indicated inFIG.8, which shows the braking device mounted on the disc9.

In the description which follows, the terms “inner” and “outer” denote the edges or areas of the brake pad10(or of its components) which are located respectively closest to and furthest from the axis of rotation A, and the terms “front” and “rear” denote the edges or areas of the brake pad10(or of its components) which are located respectively upstream and downstream relative to the flow direction of the particles28emitted by the lining2(described below) which is also the direction of rotation FW.

As illustrated inFIGS.1and2, a brake pad10comprises a backing plate1, also called a backplate. The backing plate1is for example made of metal. The backing plate1is a flat plate of substantially constant thickness (for example between 3 and 7 mm), its general shape in its main plane being trapezoidal with straight or curved edges.

The backing plate1comprises a first face13on which is fixed a lining2, and a second face14which is opposite to the first face13. The backing plate1also comprises two ears (11,12), which extend in the plane of the backing plate1at two lateral ends thereof, and which serve to hold and guide the pad10.

The brake pad10further comprises a lining2made of a friction material. For example, this material is a material called “ferodo”.

The lining2is delimited by a friction face26(“rubbing” face), a mounting face20opposite to the friction face26(these two faces being parallel) and fixed to the backing plate1, an inner edge23, an outer edge24, a rear edge21, and a front edge22. The outer24, rear21, and front22edges are convex or rectilinear; the inner edge23is concave or rectilinear.

The friction face26gradually approaches the backing plate1as the lining2wears away. The thickness of the lining2(measured along the axis of rotation A) therefore decreases as it wears.

During operation, the lining2(and the rotating element9) releases particles28due to friction between the lining2and the disc9. The paths of the particles28along the friction face26are represented by dotted lines inFIGS.1and2.

The lining2is provided with at least one collection groove3that is open to the friction face26.

The groove3has a first end31and a second end32. The groove3has an opening at its first end31towards the inner edge23, and at its second end32towards the outer edge24.

“The groove3has an opening at its end towards an edge” is understood to mean that the groove3has a communicating opening at this end in proximity to the edge, in other words either by extending through the backing plate1or by opening directly onto this edge.

In all cases, each of the ends of the groove open onto to a surface that is not the friction face26.

The depth of the groove(s)3is for example equal to the height of the lining2, meaning that the bottom of the groove3is coincident with the first face13of the backing plate1. Alternatively, the depth of the groove(s)3is less than the height of the lining2.

For example, the collection groove(s)3has a constant rectangular cross-section from its upstream end to its downstream end, and is therefore of constant thickness.

For example, the collection groove3is located near the rear edge21. This configuration makes it possible to collect more efficiently in this groove3the particles/dust resulting from braking, given that the particles naturally flow from the front to the rear of the lining2. In fact, this direction of flow is the direction of movement of the rotating element9relative to the lining2at rest.

Optionally, the lining2further comprises a second collection groove3which is located substantially midway between the front edge22and the rear edge21.

This position of the second collection groove3makes it possible to minimize undesirable vibrations of the lining2.

The braking system comprises a suction system which comprises a suction pipe40through which air is sucked in, and a blow pipe50through which air is blown. The suction pipe40comprises an air inlet orifice41which is located opposite one end of the at least one groove3, selected among its first end31and its second end32. The blow pipe50comprises an air outlet orifice51which is located opposite the other end of the at least one groove3, selected among its first end31and its second end32.

We will now describe a first embodiment, with reference toFIGS.1to4, wherein the air inlet orifice41of the suction pipe40is located opposite the second end32, and the air outlet orifice51of the blow pipe50is located opposite the first end31.

This embodiment has the advantage that the flow of air forced by the suction system takes place in the same direction as the natural flow of air in the groove3. In fact, under the influence of centrifugal force, the air flows naturally from the first end31to the second end32. The suction system is therefore more efficient.

As illustrated inFIGS.1to3, the groove3does not open directly onto the inner edge23. A wall formed by the lining2therefore separates the first end31from the inner edge23. The groove3opens to the outside via a hole17in the backing plate1. This hole17places the first face13of the backing plate1in communication with the second face14. The outlet orifice51of the blow pipe50is opposite the orifice of the hole17in the second face14. The air blown by the blow pipe50traverses the backing plate1through the hole17, enters the groove3, and flows from the first end31to the second end32. The second end32, which opens onto the outer edge24, has for its cross-section that of the groove3. The air inlet orifice41of the suction pipe40is located in the extension of the groove3. The air flowing in the groove3enters the suction pipe40through this inlet orifice41.

Alternatively, at the inner edge23the groove3is shaped as a channel90which places the remainder of the groove3in communication with the inner edge23, as shown inFIG.4. Thus, this channel90has a continuous side wall surrounded by the lining2, its first end opening into the rest of the groove3and its second end (which is thus the first end31of the groove3) opening onto the inner edge23. The outlet orifice51of the blow pipe50is opposite the second end of the channel90. The air flows from the blow pipe50and towards the suction pipe40which is directly in the extension of the groove (in the longitudinal direction of the groove3), which increases the efficiency of the suction system. This configuration improves the air flow in the groove3, including as the lining2wears away. Advantageously, the channel90is as close as possible to the backing plate1, in order to maximize the working thickness of the lining2during operation.

In addition, it is not necessary to modify the backing plate1(for example by drilling a hole, since the backing plate1is continuous for the entire length of the groove3), which simplifies the manufacture of the braking system.

The channel90is of constant cross-section, for example of circular cross-section. Alternatively, the channel90has a cross-section at its first end which is greater than its cross-section at its second end, so that air more easily enters the groove3through the channel90.

We will now describe a second embodiment with reference toFIGS.5and6, wherein the air inlet orifice41of the suction pipe40is located opposite the first end31, and the air outlet orifice51of the blow pipe50is located opposite the second end32.

The air flow which is forced by the suction system is from the second end32towards the first end31.

The groove3does not open directly onto the outer edge24. A wall formed by the lining2therefore separates the second end32from the outer edge24. The groove3opens to the outside through a hole17in the backing plate1. This hole17places the first face13of the backing plate1in communication with the second face14. The outlet orifice51of the blow pipe50is opposite the orifice of the hole17in the second face14. The air blown by the blow pipe50traverses the backing plate1through the hole17, enters the groove3, and flows from the second end32to the first end31. The first end31, which opens onto the inner edge23, has for its cross-section that of the groove3. The air inlet orifice41of the suction pipe40is located in the extension of the groove3. The air flowing in the groove3enters the suction pipe40through this inlet orifice41.

Alternatively, at the outer edge24the groove3is shaped as a channel90which places the remainder of the groove3in communication with the inner edge. Thus, the second end32of the groove3opens directly onto the outer edge24via the channel90. The outlet orifice51of the blow pipe50is opposite the end of the channel90at the outer edge24. The blowing therefore takes place from the blow pipe50into the groove3via the outer edge24and through the channel90. The backing plate1is continuous for the entire length of the groove3, so air does not pass through the backing plate1.

Advantageously, in all embodiments, there is no contact of the suction pipe40and of the blow pipe50with the lining2or with the backing plate1. Thus, after the braking phase, there is no generation of a more or less significant residual torque when the linings2and the backing plates1move away from the rotating element, this residual torque being generated by the fact that a pipe is in contact with the lining2or the backing plate1.

In this configuration, the suction pipe40and the blow pipe50are located outside the area of displacement of the backing plate1(the amplitude of this displacement resulting from wear of the lining2over the lifetime of the brake pad10) so that neither the suction pipe40nor the blow pipe50are in contact with the lining2or the backing plate1during the entire service life of the brake pad10.

In this configuration, advantageously, the inlet orifice41of the suction pipe40and the outlet orifice51of the blow pipe50are furthermore located as close as possible to the inner edge23or to the outer edge24depending on the case, so as to maximize the passage of air between the groove3on the one hand and the suction pipe40and blow pipe50on the other hand.

FIG.7illustrates the case where the lining2is provided with an additional groove3which is located near the front edge22, in addition to the first groove3located near the rear edge21. The lining2then comprises two grooves3.

The suction device therefore comprises a first blow pipe50and a first suction pipe40which enable air to flow in the first groove3, and a second blow pipe50and a second suction pipe40which enable air to flow in the additional groove3. Each of these pipes is connected to an element, which is part of the suction device, capable of causing air to flow in each of the grooves3.

This double-groove3configuration is suitable for vehicles which are subjected to braking in both directions, such as railway vehicles. Indeed, in this case the particles28released by friction of the lining2on the rotating element can flow either from the front edge22to the rear edge21, or from the rear edge21to the front edge22. The presence of two grooves3makes it possible to capture the particles in a groove3, regardless of the braking direction of the vehicle.

According to yet another embodiment, the lining2comprises another groove3(called the second groove) which is located substantially midway between the front edge22and the rear edge21, this second groove3having been described above. The additional groove3which is located near the front edge22is then a third groove3. This embodiment thus makes it possible both to minimize undesirable vibrations of the lining2and to capture particles in a groove3regardless of the braking direction of the vehicle.

In general, the suction system comprises an element capable of blowing air in the blow pipe50and an element (which is the same or a separate element) capable of sucking in air via the suction pipe40.

FIG.9illustrates the case of a suction system which comprises a pump60(which is then the above element) and a filter70, the pump60, the filter70, the suction pipe40, and the blow pipe50forming a continuous circuit. For example, there is a single pump60.

Thus, the pump60, the filter70, the suction pipe40, and the blow pipe50form, together with the groove3, a circuit in which the air flows in a closed circuit. The air filtered by the filter70is thus reused to be blown into the groove3, which causes the particles (not already captured by the filter70) to pass through the filter70several times. The probability of particles being stored in this filter70is therefore increased, and the amount of particles and dust released into the atmosphere is reduced.

According to a variant, the suction system comprises a pump60, a filter70, the suction pipe40and the blow pipe50, and a discharge valve, so as to form a circuit which is partially open. This configuration has the advantage of making it possible to adjust the speed of the blown air to the suction speed in order to optimize the collection of particles and dust in the groove3.

In this variant, the suction system comprises a control unit which is capable of controlling the discharge valve which is a solenoid valve. The system can then be optimized. Thus, depending on the rate of acceleration or deceleration of the vehicle, the control unit can suppress the blowing. For example, when accelerating the vehicle immediately following braking, it is preferable not to blow air into the groove3as this could disperse the particles present therein, but to suction only. In this case, the control unit opens the discharge valve in order to suck air from the groove3without blowing into it.

According to another variant, the element capable of sucking in air through the suction pipe40is a unit located on the path of the air in the suction pipe40, downstream of the inlet orifice41, and which is designed with an upstream inlet of smaller cross-section than its downstream outlet.