VEHICLE ASSEMBLY AND CORRESPONDING METHODS

Abstract

Assembly (100) for vehicle (1) comprising: N disc brakes (2) and a system (20) for capturing braking particles comprising: a single vacuum source (22); a pneumatic circuit (24, 26, 32, 34, 36, 38) extending from the vacuum source (22) to the N brakes (2); and a control unit (30) configured to fluidically connect the vacuum source (22) to each of the N brakes (2) sequentially. Abstract figure: Figure 1

Description

Title of the invention: VEHICLE ASSEMBLY AND CORRESPONDING METHODS Technical field

[0001] The present disclosure relates to the field of vehicle braking devices (automobiles or railways). The context relates in particular to the aspects of environmental protection by the suction of braking particles emitted by friction brakes, in particular disc brake type brakes. Prior art

[0002] Document FR 3 057 040 A1 describes a disc brake lining equipped with a collection groove and a through orifice, fluidically connected to suction means. This lining makes it possible to efficiently suck up brake dust over the entire radial height of the lining. The suction means comprise a turbine generating a vacuum which sucks up the dust to direct it towards a collection filter.

[0003] Documents DE 198 46 887 A1 and DE 196 43 869 A1 illustrate two examples of control of suction means in which the maximum suction is controlled during braking.

[0004] Document FR 3 088 395 A1 introduces the concept of compensation of the suction according to the filling level of the collection filter: in order to guarantee satisfactory suction throughout the life of the filter, the suction power can increase, if necessary.

[0005] Thus, existing systems systematically recommend activating the suction during braking phases and deactivating the suction after braking phases. Also, existing systems use one source of vacuum per brake, which makes these designs complex, expensive and heavy. Summary

[0006] The present disclosure improves the situation by providing a braking system that is simpler and just as effective in sucking up particles.

[0007] There is thus proposed a vehicle assembly comprising: N disc brakes, where N is an integer greater than or equal to two, each of the N disc brakes being provided with a particle collection element; and a braking particle capture system comprising: a single vacuum source; a pneumatic circuit extending from the vacuum source to the collection elements of each of the N brakes; and a control unit configured to fluidically connect the vacuum source to each of the N brakes successively according to a predefined cycle, such that at any given instant t, only n(t) brakes are fluidically connected to the source of depression, where whatever t, n(t) is an integer between 0 and Nl.

[0008] The inventors have demonstrated that, surprisingly, sucking up particles from a brake cyclically (and not continuously or when the brake is activated) allows a significant and sufficient level of particles to be captured. Without wishing to be bound by theory, these good results appear to come from two factors. The first factor appears to be the fact that the collection element (for example, a groove at the trailing edge of the pad, a peripheral groove, a central suction orifice, a caliper cover, a suction nozzle, a network of grooves in the pad, etc.) can serve as a particle reservoir during braking phases, even in the absence of suction. The second factor is the fact that during suction, particles stored in the asperities of the disc are sucked up, whether it is suction during brake activation or in the absence of braking.By activating the suction cyclically on a brake, i.e. decorrelated from the brake activation, it becomes possible to use a single suction source to suck up particles from several brakes without this suction source needing to be more powerful: in fact, without this cyclic suction, using a single suction source for several brakes would require this source to be as many times more powerful as there are brakes. A too powerful vacuum source involves disadvantages in terms of weight, costs, noise and size.

[0009] Each of the brakes is successively fluidically connected to the vacuum source according to a given sequence (fixed or evolving). The cycle may provide for more than one brake to be fluidically connected to the source at a given time (n>1 at any time for example). For example, the two front brakes of a vehicle can suck simultaneously, then the two rear brakes. In a variant where N=4 and where n oscillates between 1 and 2, one front brake sucks, then the two rear brakes, then the other front brake.

[0010] The “source of depression” is fluidically connected “to a brake” is to be understood as an abuse of language meaning that a flow of depression can be created between the collection elements of this brake (groove in a lining, suction nozzle, etc.) and the source of depression.

[0011] If the present document focuses on the successive suction of several brakes, the same approach can also be considered at the scale of a given brake, that is to say an alternating suction on one lining then another (or one nozzle then another), or at the scale of a lining, that is to say a successive suction on a suction element (groove) then another suction element of the same lining. These different scales can be superimposed: for example, in a given cycle, the depression can be directed towards a given brake during a given period which can be subdivided into sub-stages where the suction alternates between the dif different linings, each sub-step itself divided into sub-steps for suction in each of the grooves of the same lining.

[0012] By "control unit" is meant a hardware and / or software element dedicated to the control of the capture system or integrated into one of the main controllers of the vehicle (CAN, ECU, EMS, etc.) or of the industrial machine.

[0013] In this document, it has been chosen to use the term "connection" or the fact that two elements are "connected" to describe a physical link between two elements (most of the time by a pneumatic line). A "fluidic connection" or the fact that two elements are "fluidically connected" means that a flow of suction air is made possible between these elements (most of the time by the opening of a valve on the physical connection between the two elements).

[0014] According to another aspect, the pneumatic circuit comprises N branches respectively connected to each of the N brakes, each of the branches receiving a filter. The small capacity filters usually mounted in these systems can be used. This design therefore takes advantage of elements already in place on a given brake and therefore allows a retrofit of the new solution on existing systems.

[0015] In a variant, the pneumatic circuit comprises N branches respectively connected to each of the N brakes, and 1 branch connected to the vacuum source and receiving a single filter. This arrangement requires a larger capacity filter but facilitates maintenance operations since only one filter needs to be replaced if necessary. Also, the speed of passage of the air in the filter medium can be lower, which divides the pressure losses in the filter accordingly. Compared to the use of N filters, the use of a single, larger filter also makes it possible to store more dust before reaching clogging, to use a medium with higher filtration efficiency and to use (in total) a smaller surface area of ​​filter medium.

[0016] Compared to a situation with one turbine and one filter per brake, the arrangement of a single turbine and a single filter makes it possible to reduce the airflow power required for the turbine: in fact, if the pressure losses are 50 mbar at the seals, 10 mbar in the ducts connecting the seals to the filter and 30 mbar in a filter, the total pressure losses are 90 mbar per brake. If the flow rate is divided by N, the pressure losses in the filter are divided by N2. Thus, when N=4, the pressure losses in the filter (single replacing 4 filters) are reduced from 30 mbar to 30 / 42=1.9 mbar. The losses for a brake fall to less than 62 mbar, or 1.45 times less than the initial 90 mbar. For all 4 brakes, this amounts to a required air power 5.8 times less (1.45x4).

[0017] According to another aspect, the N branches respectively connect each of the N brakes to a single valve, itself connected to the vacuum source, the valve being capable, under the action of the control unit, of fluidically connecting the vacuum source to each of the N brakes according to the predefined cycle. This valve may comprise a single inlet connected to the vacuum source and at least N outlets, at least one of which may be connected to the inlet. The word "valve" is here to be understood in the broad sense, the valve being able to be formed of several elementary valves together performing the function described above. The valve may be a solenoid slide valve. It is thus possible to control the suction in the collection elements of each of the brakes by means of a single physical component.

[0018] According to another aspect, each of the N branches accommodates a valve which is switchable, under the action of the control unit, between an open position, in which the respective brake is fluidically connected to the vacuum source, and a closed position, in which the respective brake is not fluidically connected to the vacuum source. In this arrangement, the N valves are simpler.

[0019] It is understood that hybrid designs, i.e. designs located between the single-valve solution and the N-valve solution, can be envisaged. Thus, several pneumatic branches in series can provide a vacuum to each of the brakes by an arrangement of appropriately controlled valves. For example, two or more brakes can be connected to a common valve (e.g. a solenoid spool valve), which makes it possible to reduce the number of actuators and pneumatic lines.

[0020] According to another aspect, N is between 4 and 10. Indeed, according to the hypothesis that each of the brakes is fluidically connected to the vacuum source for a duration 1 / N of the duration of a cycle, the efficiency of the suction decreases (as shown below) when the suction time is less than 1 / 10th of the time of a cycle. It is therefore advantageous to use a single vacuum source for at most 10 brakes.

[0021] According to another aspect, in which the control unit is configured to fluidically connect the vacuum source to each of the N brakes alternately, n(t) being equal to 1 at all times.

[0022] According to another aspect, in which n is equal to 1 or 2 at each instant, n(t) alternately takes the values ​​1 or 2 during the cycle, the control unit being configured so that at a given instant, the source of depression is fluidically connected to a pair of brakes of the same axle or to a single brake.

[0023] According to another aspect, each brake comprises a pair of linings and the particle collection element comprises a groove arranged in each of the linings. The groove may be arranged in the vicinity of the trailing edge of the lining. The groove may alternatively be a peripheral groove surrounding the entire lining. The groove may be oblique and / or be provided with a suction orifice, so that the suction air flow is at least partially in the opposite direction to the movement of the disc.

[0024] According to another aspect, each brake comprises a pair of linings and the particle collection element comprises a groove arranged in a nozzle disposed spaced from the linings.

[0025] According to another aspect, each brake comprises a disc having two annular friction surfaces, respective locations of friction of the linings on the disc, each of the annular friction surfaces being delimited by an internal circle and an external circle; the collection element comprising two suction grooves fluidically connected to the vacuum source and arranged at a distance from the friction linings, each of the grooves being arranged opposite a respective annular friction surface, each groove extending from the internal circle to the external circle.

[0026] By "each groove extending from the inner circle to the outer circle" it is understood that the groove overhangs, when the disc rotates, the entirety of one of the friction surfaces. The groove may be slightly larger or slightly smaller (for example + / - 10%) than the distance between the inner circle and the outer circle.

[0027] According to another aspect, each groove is substantially rectilinear and has a width measured in a circumferential direction which is between 1 and 6 mm, and which is preferably 2 or 4 mm.

[0028] Each groove may be configured to create a suction flow that is perpendicular to the annular friction surfaces. In one embodiment, the flow is parallel to the radial direction.

[0029] According to another aspect, each groove is arranged in a respective nozzle. There are thus two nozzles facing each other on either side of the disc.

[0030] According to another aspect, each nozzle has at least one leak orifice in fluid connection with the groove. Such an orifice makes it possible to initiate an air flow in the opposite direction to the direction of movement of the disc. In one variant, the nozzle comprises two orifices on two opposite faces (upstream and downstream) of the nozzle. In another variant, two leak orifices may be provided on a rear face of the nozzle, the suction then being able to be made by a suction orifice centered relative to the two leak orifices, in order to minimize the path taken by the air in the grooves and promote the efficiency of the suction.

[0031] According to another aspect, each nozzle is arranged at an axial distance of less than three millimeters, preferably less than 0.1 mm, from the respective annular friction surface.

[0032] According to another aspect, each nozzle comprises a downstream edge provided with a seal or a brush in contact with the respective annular friction surface. Thus, an upstream edge of the nozzle, i.e. the first edge that a point of the disk “sees” during its rotation, can be at a distance from the disk while the downstream edge, provided with the seal, is in contact with the disk. This seal makes it possible to scrape off any particles to improve still their aspiration.

[0033] According to another aspect, each nozzle comprises an upstream edge and a downstream edge, the downstream edge being further from the respective annular friction surface than the upstream edge. This makes it possible to draw air downstream of the nozzle and to initiate a flow in the opposite direction to the movement of the disc.

[0034] According to another aspect, the groove of each nozzle has a longitudinal direction which is arranged in alignment with a radius of the disc, said radius being preferably angularly offset from a median radius of the linings, by an angle of between 20° and 60°. This angle materializes the clearance between the pads and the nozzles. An angle that is too small poses constraints in the design of the nozzles due to the proximity of the caliper. An angle that is too large complicates the attachment of the nozzles which can no longer be attached to the caliper.

[0035] According to another aspect, each brake comprises a fixed caliper or a floating caliper sliding relative to a yoke, the nozzles being fixed to the fixed caliper or to the yoke. This makes it possible in particular to avoid a complex system of fixing the nozzles to the vehicle.

[0036] According to another aspect, the particle capture system comprises two rigid conduits each connected to a respective nozzle and by means of which the nozzles are held in position opposite the disc.

[0037] According to another aspect, a fixing lug connects the rigid pipes to the stirrup or to the yoke, the fixing lug comprising two orifices crossed by the rigid pipes.

[0038] According to another aspect, the two grooves are arranged in a single nozzle. This single nozzle may have the same characteristics set out above for the pair of nozzles, in particular with regard to the leakage orifice(s), the upstream edge and / or the downstream edge, the seal, the distance from the disc, the angle of separation from the linings, or the attachment using a tab to the stirrup.

[0039] According to another aspect, an auxiliary groove which overlaps the sidewall of the disc connects the two suction grooves together. This auxiliary groove may be narrower than the two suction grooves.

[0040] According to another aspect, each brake comprises a disc covered with a ceramic coating. The coating may be a tungsten or chromium carbide. Since these types of discs wear less (approximately 0.2 to 0.3 mm of thickness lost between the new state and the worn state, compared to 1 mm for a cast iron disc), the positioning of the nozzles is easier and the efficiency of the suction is maintained throughout the life of the disc.

[0041] It is understood that in the preceding examples, the properties discussed for “each brake” may only apply to one or some of the brakes.

[0042] The invention also relates to a method of implementing the assembly such that described previously, the method comprising a succession of cycles each comprising a succession of suction steps, each during which exactly a number n(t) of N brakes is fluidically connected to the vacuum source, where whatever t, n(t) is an integer between 0 and Nl.

[0043] According to another aspect, in a given cycle, each of the N brakes is connected exactly once to the vacuum source. In a variant, some of the N brakes (for example the most powerful, often at the front of the vehicles) may be suctioned several times per cycle.

[0044] According to another aspect, each of the suction steps extends over the same duration. In a variant, some of the N brakes (for example the most powerful, often at the front of the vehicles) may undergo suction for a longer duration than the less powerful brakes, which produce fewer particles.

[0045] According to another aspect, over a cycle, the duration T(t) of each suction step is proportional to the number n(t) of brakes connected to the vacuum source during said step.

[0046] According to another aspect, the fluid connection cycles of the N brakes to the vacuum source take place independently of the activation of the brake.

[0047] According to another aspect, each cycle comprises a waiting step during which none of the N brakes is fluidically connected to the vacuum source, and / or during which the vacuum source is inactive. During any instant t of this step, n(t) is therefore zero. This control strategy makes it possible to optimize the electrical consumption so as not to unnecessarily create suction. In a variant, several waiting steps can be provided, for example equally distributed during each cycle.

[0048] The invention also relates to a method for implementing the assembly as described above, the method comprising switching the vacuum source from an inactive state to an active state while it is not fluidly connected to any of the N brakes, then fluidly connecting the vacuum source to one of the N brakes. It is thus possible to clean the pipes of particles that could be deposited there by creating a water hammer or a vacuum wave that will propagate when the brake(s) are depressurized. Before fluidly connecting the brake(s) to the vacuum source, it may be advantageous to allow a few seconds to elapse to allow the vacuum source to reach a nominal (for example, maximum) vacuum.

[0049] In addition to the benefits of simplicity of assembly, maintenance or control, the use of a single source of depression alternately connected to each of the brakes offers new possibilities: in fact, in comparison with a system with a turbine which sucks the particles from two brakes (simultaneously), and where each of the brakes does not benefits from only half of the nominal suction of the turbine, the solution presented here allows each brake to have access to the full power of a turbine. It is therefore possible to mount pads with larger collection elements (wider groove, larger drilling). It is also possible to use smaller diameter pipes, therefore easier to integrate on a vehicle (because they are more flexible and less bulky). Brief description of the drawings

[0050] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0051] [Fig-1] shows a vehicle, a disc brake and an assembly with a system of particle capture.

[0052] [Fig.2] shows an assembly with a particle capture system.

[0053] [Fig.3] illustrates three examples of brake pads.

[0054] [Fig.4A] shows a timing diagram of a first method.

[0055] [Fig.4B] represents a flowchart of the process of [Fig.4A].

[0056] [Fig.5A] illustrates a timing diagram of a second method.

[0057] [Fig.5B] shows a flowchart of the process of [Fig.4A].

[0058] [Fig.6] represents a flowchart of a third method.

[0059] [Fig.7] illustrates an isometric view of a disc brake.

[0060] [Fig.8] represents an isometric view of a suction nozzle.

[0061] [Fig.9] shows a sectional view of the suction nozzles mounted around the disc.

[0062] [Fig. 10] schematically illustrates a front view of the positioning of the nozzles.

[0063] [Fig. 11] shows an alternative design for a nozzle.

[0064] [Fig. 12] shows an alternative design for a nozzle.

[0065] [Fig. 13] illustrates an example of a single nozzle accommodating two grooves. Description of the embodiments

[0066] The figures represent different aspects of the invention in a schematic manner. Unless explicitly indicated otherwise, each aspect shown in a figure can be combined with other aspects shown in other figures in all technically possible combinations.

[0067] The figures and their descriptions focus on the situation where the suction alternates from one brake to another (n=1 or possibly n=0 during the waiting phases). The reader will be able to extrapolate the situations where n takes other values ​​during a cycle.

[0068] [Fig.l] illustrates a vehicle 1, road (car, van, truck, etc.) or rail (train, tram, metro, etc.), comprising at least two braking devices 2 of the disc brake type. The vehicle 1 comprises at least one braking assembly 100. The first brake 2 is annotated (1), the second is annotated (2). [Fig.l] represents synthetically the fact that there can be a number N of brakes, the Nth being noted (N) on [Fig.l]. N can be between 2 and 40, preferably between 2 and 10, more preferably N is 4, 6, 8 or 10.

[0069] Each brake 2 is essentially composed of a disc 4 secured to a wheel of the vehicle 1 and rotating at a rotational speed denoted W around an axis 6. The rotational speed W is proportional to the linear speed V of advance of the vehicle 1. A caliper 8 partially overlapping the periphery of the disc 4 contains two brake pads formed of a base and a lining 10, 12. For example, the pads may be those shown in [Fig. 3] and inspired by [Fig. 1] of document FR 3 087 238 A1, by figure 3A of document GB 2 533 476 A or by figures 3 or 4 of document KR 2020 0016 690 A. The application of a force parallel to the axis 6 by means of one or more pistons generates a braking torque by the friction of the linings 10, 12 on the respective sides of disc 4.

[0070] During a braking operation, the friction of the linings 10, 12 on the disc 4 generates particles (dust, PM10, PM2.5, etc.). These particles are harmful to the environment: their composition may contain elements that are difficult for the environment to assimilate and harmful to the respiratory functions of people who are exposed to them on a recurring basis.

[0071] A particle capture system 20 is thus provided to recover the particles produced by the brakes 2.

[0072] The capture system 20 comprises a single source of depression 22, here represented as a turbine.

[0073] The vacuum source 22 is connected by a pneumatic circuit to each brake. The pneumatic circuit may comprise N branches 24 on which a respective filter 26 is arranged.

[0074] The operation of the turbine 22 can be controlled, via a connection 28, by a control unit 30. The control unit 30 is shown schematically here. It can comprise a memory, a processor and communication buses. It can take the form of hardware and / or software elements dedicated to the control of the capture system or be integrated into one of the main controllers of the vehicle (CAN, ECU, EMS, etc.).

[0075] The pneumatic circuit may comprise, in addition to the branches 24 and the filters 26, branches 32, 34 which connect the branches 24 to the vacuum source 22. On the branches 24 may be provided valves 36 whose state (open or closed) can be controlled by the control unit 30 via a connection 38. The valves 36 are controlled according to one of the methods described below, in order to carry out the suction cycles where a certain number n(t) of branches 24 (n between 0 and Nl) is fluidically connected to the vacuum source 22 at a given time. If the [Fig.l] shows several nodes between branches 24 and branch 34, in one variant, all branches 24 join at a single node which meets branch 34, unique, leading to the source of depression 22. A hybrid variant with groups of branches 24 joining at a valve 36 is also conceivable.

[0076] The branches 24 are connected to the collection elements (44, 54, 64 in [Fig. 3]), that is to say lining elements 10, 12 in the vicinity of the interface between the linings 10, 12 and the disc 4.

[0077] The valves 36 are shown schematically. They may be solenoid valves, for example slide solenoid valves. In this example, they may be 2 / 2 valves (2 positions, 2 ports).

[0078] The control unit 30 controls the amount of current supplied to the motor of the turbine 22 and thus controls its speed. When no electrical current is supplied to the motor driving the turbine 22, the turbine 22 is stationary and no vacuum is created in the conduit 34. No suction of particles is possible. In this case, the vacuum source is said to be in an inactive state. When an electrical current is supplied to the motor driving the turbine 22, the latter starts moving and suction is possible. In this case, the vacuum source is said to be in an active state, regardless of its speed (non-zero) and / or the amplitude of the electrical current (non-zero) supplied to the motor.

[0079] The structure of the pneumatic circuit shown in [Fig.l] is adaptable to existing systems, for which each brake already has a filter.

[0080] [Fig. 2] shows a variant for the pneumatic circuit. In this example, a single filter 26 is provided on the line 34 and a single valve 36 selects the brake(s) 2 which are fluidically connected to the turbine 22. Each of the N lines 24 is directly connected to the valve 36, itself controlled by the control unit 30 via the connection 38. This design has advantages in terms of the number of components and simplification of control.

[0081] Figures 1 and 2 show two examples of structures of the pneumatic circuit. Other variants which do not require particular explanations are also conceivable, for example with a single filter 26 on the branch 34 (as in [Fig.2]) and N valves on the branches 24 (as in [Fig.l]), or conversely with N filters (as in [Fig.l]) and a single valve 36 (as in [Fig.2]). Finally, those skilled in the art will understand that other structures are possible, with any combination of filters and valves, each with a number between 1 and N.

[0082] [Fig. 3] shows three examples of brake pads 40, 50, 60 which can be used with the particle capture system. Other variants are also conceivable.

[0083] The plate 40 comprises a sole 42 on which the lining 10 is fixed. In the lining 10, a particle collection groove 44 is formed. This groove is connected to suction means.

[0084] The plate 50 comprises a peripheral groove 54 which matches the profile of the lining 10. An air inlet is provided in the center of the lining 10 and an air outlet is arranged in the groove 54.

[0085] The plate 60 is formed of a lining 10 and a skirt 62 which is intended to be arranged around the lining 10 to form a suction zone 64 between the lining 10 and the skirt 62.

[0086] Thus, various collection elements 44, 54, 64 can be provided on a plate for the suction of particles.

[0087] [Fig.4A] shows a timing diagram which illustrates the alternative suction on each of the brakes (n(t)=1 for all t). In this figure, 4 time lines are represented for each of the four brakes, that is to say when N is equal to 4. The reader will easily be able to extrapolate the operation when N takes other values.

[0088] The horizontal axis is the time axis. Each axis corresponds to one of the brakes. The notches represent the fluid connection of the given brake to the vacuum source.

[0089] At time t0, the first brake (1) is connected to the vacuum source, until time t1. At time t1, the fluid connection of the first brake (1) with the vacuum source is interrupted and simultaneously the second brake (2) is connected to the vacuum source. At time t2, the fluid connection of the second brake (2) with the vacuum source is interrupted and simultaneously the third brake (3) is connected to the vacuum source. At time t3, the fluid connection of the third brake (3) with the vacuum source is interrupted and simultaneously the fourth brake (4) is connected to the vacuum source. At time t4, the fluid connection of the fourth brake (4) with the vacuum source is interrupted and simultaneously the first brake (1) is connected to the vacuum source. All these steps describe a cycle C which is repeated continuously.

[0090] The durations between t0 and t1, between t1 and t2, between t2 and t3, and between t3 and t4 can all be equal to a duration noted T. Thus, in this example, all the fluid connection phases of each of the brakes have the same duration T.

[0091] The suction duration T for each brake can be between 5 seconds and 2 minutes, preferably between 10 seconds and 1 minute.

[0092] Other configurations are naturally possible. For example, the suction duration of two of the four brakes (the largest) can be longer, for example by 20% or 30% of the suction duration of the other two brakes.

[0093] The most powerful brakes may for example be two brakes joined in the cycle (for example (1) and (2)). Thus, the cycle comprises two long phases followed by two short phases. Alternatively, the most powerful brakes may be spaced in the cycle (for example brakes (1) and (3)). The cycle then comprises an al between long and short phases. In a variant, several suction phases for the same brake can be reproduced during the same cycle.

[0094] Also, in a variant where n(t) varies, the steps during which more brakes are sucked can last longer than the steps where a smaller number of brakes are connected to the vacuum source. Thus, the duration of a step becomes a variable T(t) which can be proportional to n(t).

[0095] [Fig.4B] shows a flowchart illustrating a method 1000 related to [Fig.4A], generalized to N brakes. The method 1000 comprises a step 1100.1 of fluidly connecting the first brake to the vacuum source, followed by a step 1100.2 of fluidly connecting the second brake to the vacuum source, followed by as many similar steps for the other brakes up to step 1100.N. At each instant, only one brake is fluidly connected to the vacuum source. After step 1100.N, the cycle starts again at step 1100.1.

[0096] [Fig.5A] shows a method in which the start of suction of a brake is not always simultaneous with the stopping of suction of another brake. In the example illustrated, a waiting step 2200 begins at time t4 (when suction of the fourth brake stops). The first brake does not start to suck again until time t5. During this waiting step, no brake is fluidically connected to the vacuum source and / or the vacuum source is inactive. It is understood that several waiting steps, distributed during the cycle, can be provided. For example, each stopping of suction of a brake can be followed by a waiting step, before starting suction of another brake. Thus, the cycle is composed of suction steps where n(t)=1 and waiting steps where n(t)=0.

[0097] If we denote by T the duration of each fluidic connection phase, or the average duration of these phases when they are not of identical durations, the waiting step has a duration T' which can be greater or less than T. For example, T' can be double or triple T. In a variant, T'=N*T.

[0098] It is understood that in the same way as described in connection with [Fig.4A], some brakes may suck longer than others, or several times during a cycle.

[0099] [Fig.5B] shows a flowchart illustrating a method 2000 in relation to [Fig.5A], generalized to N brakes. The method 2000 comprises a step 2100.1 of fluidic connection of the first brake to the vacuum source, followed by a step 2100.2 of fluidic connection of the second brake to the vacuum source, followed by as many similar steps for the other brakes up to step 2100.N. At each instant, only one brake is fluidically connected to the vacuum source (because n(t)=1 during these steps). After step 2100.N, the cycle continues with a waiting step 2200 (n(t)=0 during this step). After the waiting step 2200, the cycle starts again at step 2100.1. As mentioned above, a waiting step can also be planned between a step 2100.x and a step 2100.X+1 (x integer from 1 to N).

[0100] Whether in method 1000 or 2000 (figures 4 or 5), the duration during which a given brake is not in the suction phase can be between 30 seconds and 30 minutes, preferably between 4 and 10 minutes. Advantageously, the ratio, for each of the brakes, between the suction duration and the non-suction duration can be between 1 / 3 and 1 / 10.

[0101] [Fig. 6] illustrates a method 3000 for using the assembly described in figures 1 or 2. The method 3000 consists of blocking all fluid connections with the brakes, creating a vacuum, then opening one or more connections with the brakes. Thus, step 3100 consists of closing the valve(s) of the pneumatic circuit. Step 3200 consists of activating or maintaining the vacuum source, for example until a desired vacuum is reached. Step 3300 consists of opening one or more of the valves of the pneumatic circuit, thus creating a water hammer or a suction wave which propagates in the pneumatic circuit to detach the particles adhering to the internal walls of the pneumatic lines and the collection groove. The method 3000 can be repeated for each of the brakes, one after the other, or for any combination of brakes, until all the lines are cleaned.

[0102] In the examples presented in the preceding figures, it is implicit that the valves are controlled by the control unit to be opened or closed, or to operate a given fluid connection between the vacuum source and a given brake.

[0103] The reasons that allow effective particle capture despite intermittent suction are explained below.

[0104] The following table shows the quantities of PM 10 particles detected (produced by the brake and not captured) during a standardized WLTP cycle, according to different suction configurations (in mg per km and per vehicle brake): Standard pad without suction groove or hole Pad with a collection groove No suction Continuous suction Suction during braking phases only No suction 8.0 1.8 2.7 3.8 Table 1

[0105] It is observed that the simple fact that a lining has a collection groove halves the quantity of particles escaping into the environment. This confirms the fact that it is not essential to vacuum the particles precisely during braking to have an impact on the captured particles. Of course, if no vacuuming is ever carried out, the groove fills up and its ability to serve as a reservoir disappears.

[0106] The above tests were conducted with a groove arranged in a downstream portion of the brake lining, i.e. the portion of the lining last seen by a given point on the disc in its trajectory. This is the generally optimal arrangement for collecting particles that have been torn from the lining.

[0107] Other tests, carried out by placing a groove in the upstream part of the lining (or carried out with the same system but with an opposite direction of rotation of the disc) have shown that continuous suction or only during braking phases made it possible to capture approximately 40% of the particles produced. This means that it is possible to capture particles which have not just been torn from the lining. In all probability, these particles are therefore those which are deposited in the asperities of the disc.

[0108] The following table shows the quantities of PM10 particles detected (produced by the brake and not captured) during a standardized WLTP cycle, according to different suction configurations (in mg per km and per vehicle brake): No suction (standard pad) Continuous suction Suction during braking phases only Cyclic suction (Tl=1min; T2=6min) 8.0 1.8 2.7 2.6 Table 2

[0109] It appears that cyclic suction is as effective as suction that is limited to braking sequences. The capture is approximately 67% of the PM10 particles produced. Cyclic suction allows one turbine to be used for several brakes.

[0110] The following table shows the quantities of PM 10 particles detected (produced by the brake and not captured) during a standardized WLTP cycle, for different suction configurations (in mg per km and per vehicle brake): Continuous suction Cyclic suction (Tl=1min; T2=3min) Cyclic suction (Tl=1min; T2=6min) Cyclic suction (Tl=1min; T2=13min) Cyclic suction (Tl=1min; T2=27min) 1.8 2.2 2.6 3.6 3.7 Table 3

[0111] Tests with different values ​​of T1 and T2 show that when the T1 / T2 ratio is less than 10%, the quantity of particles detected (produced and not captured) is close to 3.7 mg / km / brake, which is the quantity detected in the absence of suction. Thus, depending on the chosen efficiency threshold (for example a threshold of 67%), using a single suction turbine for more than 10 brakes is not desirable because the suction time per brake becomes insufficient compared to the non-suction time. For lower chosen (or regulatory imposed) efficiency thresholds, it is possible to provide only one turbine for more than 10 brakes.

[0112] The invention has been illustrated by means of a disc brake but it is also applicable to other types of friction brake, comprising a rotor and (at least) one friction lining. Thus, the invention can also relate to a vehicle assembly comprising: N rotor brakes (disc, drum or other), where N is an integer greater than or equal to two, each of the N brakes being provided with at least one friction lining intended to rub against the rotor during a braking phase, each lining having a particle collection element; and a braking particle capture system comprising: a single vacuum source; a pneumatic circuit extending from the vacuum source to the lining collection elements of each of the N brakes; and a control unit configured to fluidically connect the vacuum source to each of the N brakes alternately.

[0113] Figures 7 to 13 show means for collecting particles which may be an alternative to the grooves 44, 54, 64, or be complementary to them.

[0114] [Fig.7] shows an isometric view of suction means arranged near the disc 4. The disc 4 comprises, on each side, an annular friction surface 5 delimited by an internal circle C1 of radius RI and an external circle C2 of radius R2. The annular friction surface 5 is the set of points seen by the linings 10, 12 during rotation of the disc 4.

[0115] In this example, the caliper 8 is floating, that is to say it is movable in sliding relative to a yoke 9 fixed to the hub of the wheel. The invention is obviously adaptable to a brake with a fixed caliper.

[0116] In order to suck up the particles lodged in the asperities or on the surface of the disc 4, two nozzles 140 are arranged close to the disc 4, each facing one of the two annular friction surfaces 5. Rigid conduits 148, 149 are provided to, on the one hand, fluidically connect the nozzles 140 to the vacuum source 22 and, on the other hand, to maintain the nozzles 140 in position opposite the disc 4.

[0117] A fixing lug 150 makes it possible to fix the rigid pipes 148, 149 to the yoke 9. The rigid pipes 148, 149 pass through two orifices 152 of the lug 150, with a tight fit. A third orifice makes it possible to fix the lug 150 to the yoke 9. The lug 150 may have a V shape. In a variant, the lug is formed in the yoke 9. The pipes 148, 149 project from the lug 150. They may be connected to the vacuum source 22 by means of hoses (not shown).

[0118] The conduit 148 may have a U shape and the conduit 149 may be straight.

[0119] [Fig.8] shows an isometric view of a nozzle 140. The nozzle includes an edge upstream 141 (i.e. which is seen by a point of the disc first) and a downstream edge 142 (seen last). The downstream edge 142 may be provided with a seal (for example brush or elastomer) which scrapes the disc 4. In a variant, or in combination, the downstream edge 142 may be further from the disc than the upstream edge, for example by a distance of at least 50% greater.

[0120] A groove 146 makes it possible to create a suction air flow having a direction mainly perpendicular to the surface 5 of the disc 4. The groove may be parallel to the longitudinal direction A of the nozzle 140. In the circumferential direction, the groove 146 may have a substantially constant width over its entire radial length. The width of the groove 146 may be between 1 and 6 mm, and may preferably be 4 mm. The groove may have a depth of a few millimeters, preferably approximately 0.5 mm. Too great a depth (for example 15 mm) is not relevant for the efficiency of the suction.

[0121] At least one leak orifice 143 may be provided on a rear face of the nozzle. This orifice 143 is in fluid connection with the groove and encourages the creation of a flow having a component in the opposite direction to the direction of movement of the disk, which may have advantages so that the particles do not remain stuck in the groove. The position and number of leak orifices 143 may vary: two orifices 143 may be provided, not only on the downstream face (as drawn in [Fig.8]) but also on the upstream face of the nozzle 140. A leak orifice 143 may be provided at the rear of the nozzle (the face of the nozzle opposite that which faces the disk). In this configuration, the suction port 147 may be located at one end (along the axis A) of the groove 146, and the leak port 143 may be located at another end of the groove 146.

[0122] The nozzle 140 may have a substantially longitudinal, elliptical or oval shape, with a longitudinal axis A. In a variant not illustrated, the nozzle 140 has a different shape, for example a half-moon.

[0123] The pipe 148, 149 creates a suction in the groove 146. A suction orifice 147 is provided for this purpose in the nozzle 140.

[0124] [Fig.9] shows a sectional view of the installation of the nozzles 140. In this For example, the suction orifice 147 is centered relative to the groove 146 in the longitudinal direction A. The groove 146 of the nozzles 140 faces the friction surfaces 5 of the disc 4. The nozzles 140 are at a distance B from the friction surfaces 5. The distance B may be less than 3 millimeters or even 0.1 millimeters.

[0125] The pipe 148 forms a U and the pipe 149 is straight. In this example, the conduits 148, 149 are coplanar but other designs are possible.

[0126] In the examples of Figures 7 to 9, the nozzles 140 are arranged symmetrically but other arrangements are possible. These may be angularly offset from each other or may be of different design.

[0127] [Fig. 10] schematically shows the positioning of the nozzles 140. The fittings 10, 12 may define a median radius R0 and the longitudinal axis A of the nozzles 140 may be arranged in alignment with a radius R, angularly offset from the radius R0 by an angle a. This angle is preferably between 20° and 160°. The bracket does not always allow a smaller angle to be provided. Too large an angle is not necessarily compatible with the nozzles being fixed by a bracket and may therefore complicate the nozzle fixing.

[0128] Figures 11 and 12 illustrate two design variations of the nozzle 140.

[0129] In [Fig. 11], the suction line 148, 149 is parallel to the groove 146. The suction flow has a direction substantially perpendicular to the surface of the disc.

[0130] [Fig. 12] shows a pair of nozzles 140 with two leakage ports 143 at both radial ends of groove 146. Air is drawn in from both the disc side and the ports 143, forcing an airflow into the groove that is parallel to the friction surfaces of the disc.

[0131] [Fig. 13] shows an example in which a single nozzle 140 receives both grooves 146. This nozzle may have a general U shape. The suction may be done by a single pipe 48, arranged in the plane of the disc. A narrower auxiliary groove 160 may connect the two grooves 146. For example, the circumferential thickness of the auxiliary groove is half the circumferential thickness of the grooves 146. The auxiliary groove 160 overlaps the side of the disc.

Claims

Claims

1. Assembly (100) for vehicle (1) comprising: - N disc brakes (2), where N is an integer greater than or equal to two, each of the N disc brakes (2) being provided with a particle collection element (44, 54, 64, 146); and - a system (20) for capturing braking particles comprising: • a single vacuum source (22); • a pneumatic circuit (24, 26, 32, 34, 36, 38, 148, 149) extending from the vacuum source (22) to the collection elements (44, 54, 64, 146) of each of the N brakes (2); and • a control unit (30) configured to fluidly connect the vacuum source (22) to each of the N brakes (2) successively according to a predefined cycle (C), in such a way that at any given time t, only n(t) brakes are fluidly connected to the vacuum source (22), where whatever t, n(t) is an integer between 0 and N1.

2. Assembly (100) according to claim 1, in which the pneumatic circuit (24, 26, 32, 34, 36, 38) comprises N branches (24) respectively connected to each of the N brakes (2), each of the branches (24) receiving a filter (26).

3. Assembly (100) according to claim 1, in which the pneumatic circuit comprises N branches (24) respectively connected to each of the N brakes (2), and 1 branch (34) connected to the vacuum source (22) and accommodating a single filter (26).

4. Assembly (100) according to one of claims 2 or 3, in which the N branches (24) respectively connect each of the N brakes (2) to a single valve (36), itself connected to the vacuum source (22), the valve (36) being capable, under the action of the control unit (30), of fluidically connecting the vacuum source (22) to each of the N brakes (2) according to the predefined cycle (C).

5. Assembly (100) according to one of claims 2 or 3, in which each of the N branches (24) accommodates a valve (36) which is switchable, under the action of the control unit (30), between an open position, in which the respective brake (2) is fluidically connected to the vacuum source (22), and a closed position, in which the respective brake (2) is not fluidically connected to the vacuum source (22).

6. Assembly (100) according to one of claims 1 to 5, in which N is between 4 and 10.

7. Assembly (100) according to one of claims 1 to 6, in which the control unit (30) is configured to fluidically connect the vacuum source (22) to each of the N brakes (2) alternately, n(t) being equal to 1 at all times.

8. Assembly according to one of claims 1 to 6, in which n(t) alternately takes the values ​​1 or 2 during the cycle (C), the control unit (30) being configured so that at a given instant, the vacuum source (22) is fluidically connected to a pair of brakes of the same axle or to a single brake.

9. An assembly (100) according to one of claims 1 to 8, wherein each brake (2) comprises a pair of linings (10, 12) and the particle collection element comprises a groove (44, 54, 64) arranged in each of the linings (10, 12).

10. An assembly (100) according to one of claims 1 to 9, wherein each brake (2) comprises a pair of linings (10, 12) and the particle collection element comprises a groove (146) arranged in a nozzle (140) disposed at a distance from the linings (10, 12).

11. An assembly (100) according to claim 10, wherein each brake (2) comprises a disc (4) having two annular friction surfaces (5), respective locations of friction of the linings (10, 12) on the disc (4), each of the annular friction surfaces (5) being delimited by an inner circle (Cl) and an outer circle (C2), the collection element comprising two suction grooves (146) fluidly connected to the vacuum source (22) and arranged at a distance from the friction linings (10, 12), each of the grooves (146) being arranged opposite a respective annular friction surface (5), each groove (146) extending from the inner circle (Cl) to the outer circle (C2).

12. An assembly (100) according to claim 11, wherein each groove (146) is substantially rectilinear and has a width measured in a circumferential direction which is between 1 and 6 mm, and which is preferably 2 or 4 mm.

13. An assembly (100) according to one of claims 11 or 12, wherein each groove (146) is arranged in a respective nozzle (140).

14. An assembly (100) according to claim 13, wherein each nozzle (140) has at least one leak orifice (143) in fluid connection with the groove (146).

15. Assembly (100) according to one of claims 13 or 14, in which each nozzle (140) is arranged at an axial distance (B) of less than three millimeters, preferably less than 0.1 mm, from the respective annular friction surface (5).

16. Assembly (100) according to one of claims 13 to 15, in which each nozzle (140) comprises a downstream edge (42) provided with a seal (44) or a brush in contact with the respective annular friction surface.

17. An assembly (100) according to one of claims 13 to 16, wherein each nozzle (140) comprises an upstream edge (141) and a downstream edge (142), the downstream edge (142) being further from the respective annular friction surface (5) than the upstream edge (141).

18. Assembly (100) according to one of claims 13 to 17, in which the groove (146) of each nozzle (140) has a longitudinal direction (A) which is arranged in alignment with a radius (R) of the disc (4), said radius (R) being preferentially angularly offset from a median radius (R0) of the linings (10, 12), by an angle (a) of between 20° and 60°

19. Uv . Assembly (100) according to one of claims 13 to 18, in which each brake (2) comprises a fixed caliper or a floating caliper (8) sliding relative to a yoke (9), the nozzles (140) being fixed to the fixed caliper or to the yoke (9).

20. Assembly (100) according to one of claims 13 to 19, in which the particle capture system (20) comprises two rigid conduits (148, 149) each connected to a respective nozzle (140) and by means of which the nozzles (140) are held in position opposite the disc (4).

21. Assembly (100) according to claims 19 and 20, in which a fixing lug (150) connects the rigid pipes (148, 149) to the stirrup or to the yoke (9), the fixing lug (150) comprising two orifices (152) crossed by the rigid pipes (148, 149).

22. An assembly (100) according to one of claims 11 or 12, wherein the two grooves (146) are arranged in a single nozzle (140).

23. An assembly (100) according to claim 22, wherein an auxiliary groove (160) which overlaps the flank of the disc connects the two suction grooves (146).

24. An assembly (100) according to one of claims 1 to 23, wherein each brake comprises a disc (4) covered with a ceramic coating.

25. Method (1000, 2000) for implementing the assembly according to one of claims 1 to 24, the method comprising a succession of cycles (C) each comprising a succession of suction steps (1100.1, 1100.2, ... 1100.N, 2100.1, 2100.2, ... 2100.N), each during which exactly a number n(t) of N brakes (2) is fluidically connected to the vacuum source (22), where whatever t, n(t) is an integer between 0 and N1.

26. Method according to claim 25, wherein in a given cycle (C), each of the N brakes (2) is connected exactly once to the vacuum source (22).

27. ​​Method according to one of claims 25 or 26, in which each of the suction steps (1100.1, 1100.2, ... 1100.N, 2100.1, 2100.2, ... 2100.N) extends over the same duration (T).

28. Method according to one of claims 25 to 27, in which over a cycle, the duration (T(t)) of each suction step (1100.1, 1100.2, ... 1100.N, 2100.1, 2100.2, ... 2100.N) is proportional to the number n(t) of brakes connected to the vacuum source during said step.

29. Method according to one of claims 25 to 28, in which the cycles (C) of fluid connection of the N brakes (2) to the vacuum source (22) take place independently of the activation of the brake (2).

30. Method according to one of claims 25 to 29, in which each cycle (C) comprises a waiting step (2200) during which none of the N brakes (2) is fluidically connected to the vacuum source (22), and / or during which the vacuum source (22) is inactive.

31. Method (3000) for implementing the assembly according to one of claims 1 to 24, comprising the permutation of the vacuum source from an inactive state to an active state while it is not fluidically connected to any of the N brakes, then the fluidic connection (3300) of the vacuum source (22) to one of the N brakes (2).

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