System for capturing braking particles

Abstract

The invention relates to a method for implementing a system (20) for capturing braking particles of a disc brake, the capturing system comprising suction means (22, 24, 26) for suctioning particles, controlled by a control unit (30), the method comprising: monitoring the speed of rotation of the disc (4); and controlling a non-zero suction level when the speed of rotation (W) of the disc is substantially constant and non-zero. The invention also relates to a capturing system thus configured and to a corresponding vehicle.

Description

BRAKE PARTICLE CAPTURE SYSTEM

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

[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 maximum suction is controlled during braking.

[0004] Document FR 3 088 395 A1 introduces the concept of suction compensation based on 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] Another example is given in document CH 687 013 A5 which distinguishes between braking carried out while the vehicle is moving at low speed (< 20 km / h) and during which no suction is carried out, and braking carried out while the vehicle is moving at higher speed (> 20 km / h), during which the suction of brake dust is controlled.

[0006] Thus, existing systems systematically recommend activating suction during braking phases and deactivating suction after braking phases. However, as explained below, the inventors of the present disclosure have highlighted the fact that, surprisingly, braking particles could be emitted outside of braking phases. Summary

[0007] The present disclosure thus provides a particle capture system and related methods, which significantly increase the quantity of brake particles recovered.

[0008] A method is proposed for implementing a system for capturing braking particles of a disc brake, the capture system comprising particle suction means controlled by a control unit, the method comprising: monitoring the rotational speed of the disc; and controlling a non-zero suction level when the rotational speed of the disc is substantially constant and non-zero.

[0009] The inventors have demonstrated that particles can be emitted even outside of braking phases, and in particular when the disc speed is substantially constant. Without being bound by theory, this production of particles at constant speed could be linked to mechanical equilibrium.

[0010] By "suction level" is meant a measurable physical parameter related to suction, this physical parameter being able to be the depression (absolute value of a negative pressure), the suction flow velocity or the suction flow rate. Thus, a higher level suction has a greater depression, a greater flow velocity and / or a greater suction flow rate. In the present disclosure, one level is considered higher than another when the measurable parameters of the two levels differ strictly, for example by a relative value of at least 1% or at least 5% or at least 10% of one of these parameters. In certain examples according to the present disclosure, this difference can be increased to 100%, one of the levels being double the other, or one of the levels being an absence of suction.

[0011] The "suction means" comprise one or more elements configured to create a negative pressure flow in the vicinity of the interface between the disc and the friction lining. The documents cited above give examples of structures for generating this negative pressure flow. These include, in particular, a caliper cover, a suction nozzle, a lining with a groove and a through-orifice. The vacuum source may consist of a turbine. The suction level may be adjusted by acting directly on the vacuum source, for example the intensity supplying the turbine to increase or decrease its rotation speed. Alternatively or in addition, the suction level may be adjusted indirectly: a valve may be interposed between the vacuum source and the disc / lining interface, the valve totally or partially filtering the suction power of the vacuum source.

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

[0013] During a braking operation, the suction means may produce a non-zero suction level which may correspond to the maximum suction that the suction means can produce. The suction level outside the braking phases may be different from the suction level applied during braking, for example the vacuum outside braking may be at least 10%, at least 20%, at least 30%, at least 40% or at least 50% lower (in absolute value) than the vacuum during braking and / or the air flow outside braking may be at least 10%, at least 20%, at least 30%, at least 40% or at least 50% higher than the air flow during braking.

[0014] The intended application includes disc brakes for motor vehicles or railways or industrial disc brakes. In this type of brake, one or more linings come into contact with one or more discs. It is understood that the particle capture system of the present disclosure is also capable of capturing particles from other types of brake, particularly drum brakes.

[0015] By "substantially constant speed" it is understood that the rotational speed of the disk varies by less than 10%, less than 5%, or less than 2% over a time interval greater than 5 seconds or greater than 10 seconds or greater than 30 seconds.

[0016] Monitoring the rotation speed of the disc can be done by any means, direct or indirect, such as, for example, a speed sensor (tachometer, rev counter, optical, magnetic, electrical, ESP, ABS, etc.) connected directly or indirectly to the control unit.

[0017] The rotational speed of the disc may be proportional to a physical reality in which the system is used. For a vehicle, this may be the linear speed of the vehicle (V=RW where R is the radius of the vehicle wheel). Thus, in all examples of the present disclosure, when the brake is a vehicle brake, the expression "rotational speed of the disc" may be replaced by "vehicle speed". For an industrial machine, the physical reality in question may be the power delivered (power = torque x W) when the torque is constant over a sufficient range of values ​​of rotational speed of the disc. Thus, in all examples of the present disclosure, when the brake is an industrial machine brake, the expression "rotational speed of the disc" may be replaced by "machine power".

[0018] Thus, the rotation speed of the disc can be measured indirectly: for a vehicle, it can be measured on the crankshaft; for an industrial machine, it can be estimated by measuring the power delivered.

[0019] According to another aspect, the control of a suction level is conditional on the brake having a residual braking torque greater than a threshold value.

[0020] Indeed, the inventors' investigation efforts have established that a residual braking torque, due to the permanent contact of the linings on the disc even in the absence of braking force, could have a significant impact on particle emissions. In extreme situations, over the total lifetime of the linings, 30 to 40% of particle emissions could occur due to this residual torque. Thus, when the residual torque induced by the disc / lining / caliper triplet is greater than a predetermined threshold, it is advantageous to configure the control unit to perform suction.

[0021] According to another aspect, the residual braking torque of the brake is previously established by calibration on a brake bench or a roller bench. The method thus comprises an initial calibration step in which the residual torque is measured, and the control unit is configured to perform suction if this torque is greater than a threshold.

[0022] According to another aspect, the residual braking torque is determined by identifying the disc / pads / caliper triplet present and by consulting a database listing the residual torques of several triplets.

[0023] The control unit can be configured for a specific brake (disc / pads / caliper triplet) or a database including the disc, pad and caliper triplets (their design, material, etc.) can be created. The control unit can access this database, identify the disc, pads and caliper present to identify the disc / pads / caliper triplet in play and retrieve the associated residual torque value, in order to take it into account in the control of the suction means.

[0024] The inventors were indeed able to show that the residual torque depended mainly on the three elements implemented in the brake: the disc (its design, its material, its level of wear), the linings (their shape, their constituent material, their level of wear, etc.) and the caliper (its design, its constituent material, etc.). Since the linings and the discs are destined to be replaced during the life of a vehicle or an industrial machine, it may be relevant not to configure the control unit for a single suction strategy but so that it can offer the possibility of being configured according to the disc / linings / caliper triplet present.

[0025] The configuration of the control unit can be automatic (by detection, e.g. RFID) of the identifiers of the elements in play, or can be manual (by manual entry from an operator).

[0026] According to another aspect, the residual braking torque is measured during operation. Thus, the control unit can take into account a change in the residual braking torque during the life of the brake.

[0027] In another aspect, the non-zero suction level is proportional to the residual braking torque. It is thus possible to configure the control unit to produce suction in proportion to the residual braking torque.

[0028] Thus, when the residual torque is considerably higher than the threshold, the suction level can be controlled to be greater than when the residual torque is slightly higher than the threshold. Alternatively, other conversion laws between the residual torque and the suction level can be used (quadratic, exponential, etc.).

[0029] According to another aspect, the threshold value is between 1 Nm and 10 Nm. Indeed, below 1 Nm, the quantity of particles emitted is not sufficient for the balance between the energy consumed for suction and particle capture to be beneficial to the environment. Above 10 Nm, suction would be limited for vehicles or machines that produce extremely many particles, which could represent too low a proportion of vehicles / machines in a given fleet. Preferably, the threshold value is between 1 Nm and 5 Nm. The brake may have a maximum braking torque and the braking torque threshold value may be 5% of the maximum torque.

[0030] In another aspect, the suction level is proportional to the rotational speed of the disc. The suction level can be both proportional to the residual torque (measured before driving) and proportional to the rotational speed (in real time): p=k*Cc*k'*W (where p is the depression, k and k' are coefficients, Cc is the residual torque and W is the rotational speed of the disc (directly proportional to the forward speed of a vehicle).

[0031] In another aspect, the control of a suction level is conditional on the disk exceeding a rotational speed threshold.

[0032] The invention also relates to a system for capturing braking particles emitted by a disc brake, the capture system comprising: particle suction means whose suction level is adjustable; a control unit configured to control the suction level of the suction means in accordance with the method described above.

[0033] The invention also relates to a motor or railway vehicle comprising: a disc brake; and a system for capturing braking particles emitted by the disc brake; the capture system comprising: particle suction means; and a control unit regulating the state of the suction means, the vehicle being remarkable in that the control unit is configured to control a non-zero suction level of the suction means when the vehicle maintains a cruising speed.

[0034] A cruising speed is to be understood as a substantially constant speed: the speed of the vehicle varies by less than 10%, less than 5%, or less than 2% over a time interval greater than 5 seconds or greater than 10 seconds or greater than 30 seconds.

[0035] According to another aspect, the vehicle comprises means for identifying the linings, the caliper and the disc, allowing, automatically or under the action of an operator, the control unit to be informed of the identifiers of the disc / linings / caliper triplet.

[0036] Contact or contactless sensors (e.g. RFID) or a user interface (e.g. OBD2) can be used to inform the control unit appropriately. Alternatively, the operator can manually select a suction strategy (e.g. in a vehicle control menu).

[0037] Thus, the various aspects of the present invention make it possible to preserve the environment by improving the capture of particles emitted by disc brakes.

[0038] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

[0039] shows a vehicle, a disc brake and a particle capture system.

[0040] shows a first reading of particle emissions.

[0041] shows a second reading of particle emissions.

[0042] shows a process.

[0043] The figures represent different aspects of the invention in a schematic manner. Unless explicitly indicated otherwise, each aspect shown in a figure may be combined with other aspects shown in other figures in any technically possible combination.

[0044] Illustrates a possible application for the present disclosure. A vehicle 1, automobile (car, van, truck, etc.) or railway (train, tram, metro, etc.), comprises a braking device 2 of the disc brake type. It is understood that the invention is not limited to this type of vehicle or to this type of brake: indeed, the person skilled in the art will know how to adapt the invention for other vehicles (motorcycle, bicycles, etc.) or for other types of brakes (drum, multi-disc, etc.).

[0045] The brake 2 is essentially composed of a disc 4 secured to a wheel of the vehicle 1 and rotating at a rotation speed denoted W around an axis 6. The rotation 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 encloses two linings 10, 12. 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 faces of the disc 4.

[0046] 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.

[0047] A particle capture system 20 is thus provided for recovering the particles. Such a system 20 may for example be in the form presented in document FR 3 057 040 A1 or in another form, in particular according to the examples in the patent literature published in the name of the company Tallano.

[0048] The capture system 20 may thus comprise a vacuum source 22, here represented as a turbine, which is fluidically connected, for example by means of a (flexible) pipe 24, to a zone close to the interface between the linings 10, 12 and the disc 4. In one example, the linings 10, 12 may be provided with a through hole and the pipe 24 may be connected to the rear face of the linings 10, 12. The pipe 24 may comprise a filter 26 or a particle collection tank. This filter 26 may for example be dimensioned so as not to require maintenance and so as to be able to be replaced simultaneously with a replacement of the linings 10, 12. The filter 26 may be arranged downstream or upstream of the turbine 22.

[0049] 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 (ICAN, ECU, EMS, etc.) or of the industrial machine.

[0050] A sensor 32 can detect the rotational speed of the disc 4 and transmit it to the control unit. This sensor 32 can be integrated into an assembly arranged locally near the disc 4, such as for example a brake assist system (ABS) or an electronic trajectory correction system (ESP). The sensor which sends the speed information back to the control unit can alternatively be a sensor which detects for example the rotational speed of the crankshaft and deduces therefrom the rotational speed of the disc and / or the linear forward speed of the vehicle. For industrial machines, the speed of the disc can be obtained by any suitable means.

[0051] The sensor 32 communicates a signal 34 to the control unit 30. The signal 34 can be an electrical potential which corresponds to an image of the rotational speed of the disk 4. The assembly is calibrated so that the control unit 30 can transpose the electrical potential of the signal 34 into a rotational speed value of the disk 4.

[0052] Optionally, a sensor can identify the reference of the main parts involved (for example by RFID, optical, or other) and communicate to the control unit 30, via a wired or non-wired connection, the identifiers of the disc, the pads and the caliper.

[0053] This sensor can also be integrated into a unit arranged locally near the disc 4, such as for example a brake assist system (ABS) or an electronic trajectory correction system (ESP).

[0054] The control unit 30 is capable of receiving information indicating braking in progress and can thus control the suction of particles emitted during braking. Also, and as explained below, the control unit can control suction outside (i.e. before or after) the braking phases, under certain conditions.

[0055] Illustrates a reference test in which no particle capture is carried out outside of braking.

[0056] The x-axis represents time (e.g., in seconds). The y-axis represents (1) the disc rotation speed W (e.g., in revolutions per minute); (2) the suction level p (e.g., in bar); (3) the friction torque of the pads on the disc (during and outside braking); and (4) the quantity of CPC particles (for "condensation particle counter" in English, a particle counter) released into the environment, i.e., the particles that are produced by the brake and are not captured by the capture system. As mentioned above, other physical quantities can be used to characterize the suction level or the quantity of particles emitted.

[0057] The curve shows a braking operation taking place between time Tf1 and time Tf2. During this braking operation, the speed W decreases. The suction is activated with a braking suction depression, noted pf (in absolute value). Despite the suction, there may be a temporary increase in particle emissions, as the capture system cannot claim to guarantee total capture of all the particles produced during braking.

[0058] In this illustration, after Tf2, the disc accelerates, simulating a vehicle regaining speed after braking. The slipstream is inactivated and becomes zero after Tf2. After an acceleration phase, the speed stabilizes at T3.

[0059] It is observed that the CPC particles emitted can be significant even outside of braking phases and particularly in stationary mode once the speed has stabilized.

[0060] Lamontre also shows a comparison between a system "a" and a system "b". The C axis represents the friction torque (e.g. in Nm) of the linings on the disc. During braking, the torque has the value Cf, braking torque. Outside the braking phase, by construction, the linings remain in contact with the disc without however applying sufficient force to slow the disc. This contact can generate a so-called residual torque which the inventors have established is specific to a triplet disc, linings, caliper. Thus, a brake "a" will for example have a residual torque Ca lower than a system "b" having a residual torque Cb. The residual torque is substantially constant regardless of the rotation speed of the disc.

[0061] The inventors have highlighted the implication of the residual torque value on the emission of particles: it shows that system "b" which has the greatest residual torque results in the emission of a greater number of CPCb particles than system "a" which emits fewer CPCa particles. The difference between the two curves can fade during braking: in fact the emissions peak during the braking phase can be at the same level, which is independent of the residual torque of each of the brakes. For a high residual torque, the emitted CPCb particles can change with the rotation speed.

[0062] A residual torque threshold Cc can be chosen. In this example, Ca is less than Cc and Cb is greater than Cc. This threshold characterizes a tolerable particle emission outside braking. The threshold value can be chosen appropriately depending on the application in which the brake is used. For example, for a motor vehicle, the threshold can be in a value range of 1 Nm to 10 Nm. For a railway vehicle, the threshold can be 5 Nm to 50 Nm. Too low a threshold would result in suction energy being consumed when it is not essential, which would reduce the environmental benefits of the capture system. Too high a threshold would limit particle suction for vehicles or machines that produce extremely many particles, which could represent too low a proportion of vehicles / machines in a given fleet.

[0063] Lamontre shows a suction control law that sucks at constant speed (from T3). In practice, suction can begin a few seconds after T3, once the control unit can confirm that the speed has been stabilized over a more or less long period (for example 5 seconds, 10 seconds or 30 seconds). The suction level, pb, at stabilized speed, can be lower than the suction level pf commanded during braking.

[0064] Optionally, and as illustrated in the, one of the conditions for applying this suction strategy can be the fact that the brake has a residual torque greater than a threshold (here Cb greater than Cc).

[0065] The value of pb can be proportional to the measured torque Cb and possibly to the rotational speed of the disc. Thus, the greater the torque Cb relative to Cc, the greater the value of the depression pb can be.

[0066] Optionally, the suction level pb can be equal to the suction pf, which allows the suction source to be of simpler design since it only needs to be activatable at one suction level.

[0067] It is observed that the amount of particle emissions, which is present in the absence of suction, is considerably reduced when suction is implemented.

[0068] The residual torque Cb drawn on the remains unchanged compared to the, the suction having no action on the friction torque between the linings and the disc.

[0069] It is understood that if, during the suction phase of the particles due to the residual torque, a new braking phase takes place, the suction is activated again at the pf level.

[0070] Illustrates a control method 1000. The method comprises a step 1100 of monitoring the rotational speed of the disk, or, in the case of a vehicle, the speed of the vehicle. The monitoring may be permanent and continuous. Alternatively, it may only be carried out periodically.

[0071] In parallel with the monitoring, if the control unit is informed that the speed is stabilized, it commands the suction means to suck.

[0072] Optionally, a step 1300 of determining the residual torque of the brake can condition the activation of the suction at constant speed. The residual torque can be determined on a test bench (brake bench or roller bench) before mounting the brake on the vehicle / machine. Different techniques can be used to measure the residual torque. For example, knowing the coefficient of friction between the disc and the linings, and knowing the geometry of the linings, the axial force between the linings and the disc can be measured and the residual torque deduced therefrom. Alternatively, the differential measurement between the power supplied by the motor rotating the disc (or a shaft carrying it), and the torque actually received by the disc / shaft, makes it possible to deduce the residual braking torque.Another technique aims to determine the deceleration produced by the residual braking torque when the disc – which was rotating – is suddenly no longer driven, and to deduce the residual torque from the deceleration.

[0073] The residual torque measurement 1300 can alternatively be carried out on several brakes. It is thus possible to associate each disc / pad / caliper triplet with a residual torque value.

[0074] The respective residual torques can be recorded in a database or any other form of memory. The record can take the form of a quadruplet, that is, a set of four ordered elements, three of which are the identifiers of the disc, the linings, and the caliper, and the fourth element is the value of the residual torque. The quadruplet can be denoted {Disc_ID; Lining_ID; Caliper_ID; Cr}, where Disc_ID is a disc identifier, Lining_ID is a lining identifier, Caliper_ID is a caliper identifier, and Cr is the residual torque associated with the triplet {Disc_ID; Lining_ID; Caliper_ID} that characterizes the brake.

[0075] The control unit 30 can thus be fed with this information. When it identifies the brake present, by its disc / linings / caliper triplet, it can control the suction appropriately, depending on the associated residual torque. The identification of the triplet can be carried out automatically by appropriate detectors, or be carried out manually by an operator.

[0076] Finally, the residual torque can be determined during operation, by on-board equipment.

[0077] The method of controlling the suction means may alternatively consist of controlling the suction solely on the basis of the residual torque without taking into account the speed: a residual torque above a certain threshold generates permanent suction and a residual torque below this same threshold leads to suction restricted to the braking phases, or even with a slight anticipation before braking, in accordance with the precepts of document WO 2020 / 094964 A1.

[0078] It is understood that the present invention is not limited to the examples described above and that those skilled in the art would be able to envisage variants without departing from the protection conferred by the appended claims.

Claims

Method (1000) for implementing a system (20) for capturing braking particles from a disc brake, the capture system comprising particle suction means (22, 24, 26) controlled by a control unit (30), the method comprising: monitoring (1100) the rotation speed of the disc (4); and controlling (1200) a non-zero suction level (pb) when the rotation speed of the disc is substantially constant and non-zero. Method according to claim 1, in which the control of a suction level (pb) is conditional on the fact that the brake has a residual braking torque greater than a threshold value (Cc). Method according to claim 2, in which the residual braking torque of the brake is previously established (1300) by calibration on a brake bench or a roller bench. Method according to claim 2, in which the residual braking torque is determined by identifying the disc / pads / caliper triplet present and by consulting a database listing the residual torques of several triplets. A method according to claim 2, wherein the residual braking torque is measured in operation. Method according to one of claims 2 to 5, in which the non-zero suction level (pb) is proportional to the residual braking torque (Cb). Method according to one of claims 2 to 6 in which the threshold value (Cc) is between 1 Nm and 10 Nm. Method according to one of claims 1 to 7, in which the suction level is proportional to the rotation speed of the disc. Method according to one of claims 1 to 8, in which the control of a suction level (pb) is conditional on the fact that the disk exceeds a rotation speed threshold. System (20) for capturing braking particles emitted by a disc brake (2), the capture system (20) comprising: particle suction means (22, 24, 26) whose suction level is adjustable; a control unit (30) configured to control the suction level of the suction means (22, 24, 26) in accordance with the method of one of the preceding claims. Motor vehicle or railway vehicle (1) comprising:a disc brake (2); anda system for capturing braking particles (20) emitted by the disc brake (2); the capture system (20) comprising:particle suction means (22, 24, 26); anda control unit (30) regulating the state of the suction means (22, 24, 26),the vehicle being characterized in that the control unit (30) is configured to control a non-zero suction level (pb) of the suction means (22, 24, 26) when the vehicle (1) maintains a cruising speed.

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