METHOD FOR EXTRACTING BRAKE PARTICLES

Description

technical field

[0001] The invention relates to systems for extracting brake particles in friction braking systems. Such friction braking systems can be used on road or rail vehicles. They can also be used on stationary rotor machines such as wind turbines or industrial machinery. Context and Previous Art

[0002] In such systems, as described for example in document DE4240873, a suction turbine and a particle collection filter are provided. The particles resulting from abrasion are thus gradually accumulated in the collection filter. This leads to progressive clogging of the filter and the pneumatic lines leading to it. When friction pads are used, suction grooves can be incorporated into the friction material, as taught by the applicant, for example, in document FR3057040.

[0003] Document FR3088395 provided a suitable control solution to optimize turbine control under braking and signal a filter clogging state.

[0004] The inventors did, however, notice that the pneumatic lines tended to get clogged over time, due to a small deposit of brake particles that eventually accumulated there.

[0005] The present invention aims to provide an improved solution for maintaining pneumatic lines in a satisfactory condition. Summary of the invention

[0006] To this end, a control method is proposed for a brake particle suction system for a friction braking system, the suction system comprising: at least one vacuum source, at least one suction outlet arranged near a friction interface or inside a friction part, and connected by at least one pneumatic line to the vacuum source, a control unit configured to control the vacuum source, and a means for providing information on the activation of braking, the method providing that the control unit is configured to: a-to control the source of vacuum (e.g., turbine rotation), for a braking suction sequence, based on the current braking activation information, to ensure suction as soon as (and for as long as) braking is activated, b- establish at least one cleaning suction condition, outside of braking sequences, c- as soon as at least one cleaning suction condition meets a predetermined criterion, command the vacuum source (e.g., turbine rotation) for a cleaning sequence of at least one pneumatic line, for a predetermined duration (TN).

[0007] These features allow for a high-flow pneumatic sequence, enabling the cleaning of the pneumatic lines. During operation, any whistling sound produced by this process is masked by road noise, as it is performed when the vehicle exceeds a certain speed threshold. A cleaning sequence can also be used for maintenance or diagnostic purposes.

[0008] It is noted that the braking suction sequences are carried out at low flow rate, while conversely the cleaning sequences are carried out at high flow rate, by increasing the limiting aerodynamic passage section at the suction outlet.

[0009] The term "friction interface" refers to either the brake pad / disc interface surface or the brake shoe / rim interface surface, and covers all friction braking configurations. Furthermore, "in close proximity" means that the air is drawn to the vicinity of the aforementioned interface surfaces.

[0010] It is also noted that if friction pads are used, the suction grooves made in the friction material form the suction mouth which is then arranged inside the friction part which is the friction pad.

[0011] In various embodiments of the invention relating to the process, one may optionally also use one and / or the other of the following provisions, taken separately or in combination.

[0012] According to the invention, at the stage b-,Determining the cleaning suction condition is a logical / algorithmic calculation taking into account at least one of the following arguments: the current speed of the vehicle, especially above a first speed threshold (V1), the time elapsed since the last cleaning sequence, the distance traveled since the last cleaning sequence, the number of dynamic braking operations performed since the last cleaning sequence, the prevalence of a maintenance mode (garage mode or diagnostic mode).

[0013] We use such a multi-parameter, multi-criteria condition to decide to trigger the cleaning sequence in the most optimized way possible, in other words we minimize the number of cleaning sequences in relation to a desired efficiency of maintaining the condition of the pipes / pipes.

[0014] Dynamic braking refers to braking carried out when the vehicle is not at zero speed.

[0015] According to one option, it can be stipulated that in step c-, the source of vacuum (e.g., the turbine rotation) is activated at maximum power. This maximizes the high-flow suction effect to dislodge particles that may have settled inside the pipes.

[0016] Depending on the option chosen, a predetermined duration (TN) can be selected from a range of 3 to 15 seconds. This duration is sufficient and necessary to ensure proper pipe cleaning.

[0017] Depending on the option selected, the cleaning sequence is triggered, outside of maintenance mode, only if the vehicle's current speed exceeds the first speed threshold. Therefore, the cleaning sequence is unlikely to be audible to a vehicle occupant or passerby, as its noise level is masked by road noise.

[0018] According to one option, the cleaning sequence (52) is triggered in response to a request made by a diagnostic device during maintenance mode. Thus, during a brake pad replacement, with the line disconnected and without pads, the diagnostic tool can be used to generate a vacuum suction sequence with no airflow restriction on the pad side.

[0019] According to one option, the vacuum source is formed by a turbine driven by an electric motor (11), with the control unit (6) configured to control the electric motor. This is a flexible solution in use, as the turbine speed can be adjusted according to the suction requirement.

[0020] As an option, the control unit can be configured to activate a vent solenoid valve located on the pneumatic circuit near the suction inlet during the cleaning sequence. This further increases the airflow within the pneumatic line during the cleaning sequence. When this vent solenoid valve is activated, there is no longer an airflow restriction at the friction interface.

[0021] The invention also relates to a system for suctioning brake particles from a friction braking system, the suction system comprising at least one vacuum source (1), at least one suction nozzle (83) arranged near a friction interface or inside a friction part, and connected by at least one pneumatic line to the vacuum source, a control unit (6) configured to control the vacuum source, and a means for providing information on the activation of braking in progress, the suction system being configured to implement the method as described above.

[0022] According to one option, the system may further include at least one filter (2) to collect the aspirated particles.

[0023] Depending on the option, the system includes a centralized filter and turbine, connected to four or more suction inlets. This configuration allows for a certain length of pneumatic tubing, hence the importance of being able to clean it periodically.

[0024] As an option, a vent solenoid valve (59) may be provided on the pneumatic circuit and near the suction inlet. Such a solenoid valve makes it possible to substantially increase the airflow inside the pneumatic line during the cleaning sequence, said solenoid valve allowing the pneumatic line to communicate with the atmosphere (free air) on the side of the suction inlet. Description of the figures

[0025] Other aspects, objects, and advantages of the invention will become apparent from the following description of an embodiment of the invention, given by way of non-limiting example. The invention will also be better understood with reference to the accompanying drawings, in which: There figure 1 represents a side view of an example of a friction braking device, The figure 2 represents a schematic diagram of a localized brake particle suction system for a wheel or axle. figure 3 represents a schematic diagram of a centralized braking particle suction system on multiple wheels or axles. figure 4 represents a functional schematic of a braking particle suction system, The figure 5 provides a physical illustration of the components of the brake particle suction system, The figure 6 represents a timing diagram illustrating at least one system function, The figure 7 represents a chronogram on a longer time scale, The figure 8 represents a schematic diagram illustrating a pneumatic system, The figure 9 represents another schematic diagram illustrating a pneumatic line, with a solenoid valve for venting, The Figure 10 represents a variant of the schematic diagram of a brake particle suction system. Detailed description

[0026] In the various figures, the same references designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale. General layout

[0027] There figure 1 schematically represents a friction braking system. In the illustrated case, a brake disc is shown. 9 designed to be fixed to the rotational unit of a wheel (or even an axle for railway equipment). The disc9 rotates around the axis A. According to known practice, a stirrup is positioned 7 straddling the disc and mounted on a caliper bracket. Furthermore, the caliper includes a piston configured to act on friction pads to sandwich the disc. The friction pads are mounted on brake pads or shoes, all of which are known separately and not described in detail here. The brake pads are marked 19 and represented as dotted lines in some views.

[0028] Although a diagram of a disc brake has been shown, the present invention is also suitable for drum brakes, or even brake systems with pads applied directly to the wheel rim.

[0029] A collection device is planned in place of the friction pads. 8 particles that escape from it. More specifically, a suction inlet can be installed. 83for each of the friction pads. An example can be found, for instance, in document FR3057040 from the present applicant, where particles are captured in grooves formed in the friction material. The suction opening can be formed by the groove(s) themselves connected to a through hole in the friction pad's base and communicating with a downstream passage (towards the filter).

[0030] The suction inlet 83 is connected to a source of vacuum by a pneumatic circuit. The pneumatic circuit may include a first pipe 3 and a second driving 30, as schematically illustrated in the figure 5 Of course, there can be only one 3-pipe if the filter and turbine are combined.

[0031] Generally speaking, the suction port can be located in the path of the particles as they exit the interface between the brake pad and the rotating component (disc, drum, rim, etc.). It is the vacuum or flow created at this point that contributes to good capture.

[0032] In other configurations, a cover may be provided, in which case the suction opening is formed by the outlet of the space covered by said cover.

[0033] It is therefore important to understand that the present invention can be applied regardless of the configuration of the suction inlet. 83.

[0034] Typically, for a disc brake setup, there will be a suction port. 83 on each side of the disc as illustrated in the figure 1 .

[0035] The suction inlet (or inlets, as the case may be) is connected to a filter 2by a fluid conduction called here first conduction 3, as exemplified in the figure 2 The first conduit 3 can be formed like a pipe without excluding a tunnel-like passage through a part (for example, the yoke body). The first conduit can be of varying lengths, ranging from a few tens of centimeters, for example 50 cm, up to several meters in a centralized filtering configuration as illustrated in the figure 3 .

[0036] Generally, the fluid connection between the suction inlet and filter 2 may include one or more branches, T-fittings, Y-fittings, etc. The term pneumatic circuit can also be used to refer to the fluid lines / air hose.

[0037] The fluidic connection between the suction inlet and the filter 2may include rigid sections and flexible driving sections.

[0038] Various configurations are possible between the suction inlets, the filter, and the vacuum source: one can have a filter for each suction inlet (maximum decentralized configuration), or even for each pair of suction inlets ( Fig 2 ), but it is also possible to have a single filter for a plurality of pairs of suction vents ( Fig 3 (centralized configuration), or even a single filter for the entire vehicle. This choice may be dictated by the type of vehicle, the required lifespan of the filter before clogging, various installation constraints within the vehicle, etc.

[0039] On the figures 2 , 6 and 7 We have represented a configuration in depression, with the filter interposed between the first duct 3 and the source of depression 1which draws particles through the filter, which is then under negative pressure relative to the external ambient pressure. However, in a configuration shown in the Figure 10 , The source of depression (here turbine 1) can be interposed between the first duct 3 and the filter, in which case the turbine draws in the particles and then blows them into the filter via a downstream duct noted 3' with a second sensor 23 (optional). In this case, filter 2 is under positive pressure instead of negative pressure.

[0040] The filter 2 In a typical example of implementation, it may include a filtering medium, such as paper or other, allowing air to pass through and trapping small particles contained in the flow from the suction vents.

[0041] The term 'filter' should be understood broadly here, encompassing centrifugal (cyclone-type) filter solutions, electromagnetic trapping filter solutions, and electrostatic trapping filter solutions. The term 'filter' also includes solutions where particles are directed towards an existing filter, such as a cabin air filter or a catalytic converter filter.

[0042] The particle filter 2is configured to filter air from the intake vents, including solid particles with nanometer, micrometer, or millimeter dimensions; that is, it allows air to pass through the filter medium while the particles are trapped within it. Over time, the amount of particles trapped in the filter medium increases, so filter 2 operates by accumulation, and the passage of air through the filter medium becomes progressively more difficult.

[0043] Over time and with repeated braking, particles accumulate in the pneumatic line(s). The cumulative amount increases with time and braking. This deposit varies depending on the nature and quality of the friction material, the climatic conditions encountered, etc.

[0044] In the illustrated example, the source of depression 1 is formed by a suction turbine 10powered by an electric motor 11.

[0045] In the illustrated example, the turbine with its electric motor forms a separate unit from the filter. Therefore, a second pneumatic fluid line is required. 30 to connect the turbine to the filter.

[0046] It should be noted that a configuration with the turbine and the filter in a single entity is also possible.

[0047] An optional provision may also include a pressure sensor. 22 configured to measure the pressure in the first conduit 3. On the schematic diagram of the figure 2 , the pressure sensor 22 is arranged on the path of the first conduit 3 between at least one suction port and the filter 2.

[0048] However, in an equally preferred alternative configuration, the pressure sensor 22 is arranged adjacent to or integrated with the filter 2, as illustrated in the figure 5 . Control unit

[0049] The suction system also includes a control unit 6 configured to control the turbine.

[0050] The control unit 6 is an electronic unit capable of generating a control signal to control the speed of the motor that drives the turbine according to any value between zero speed and the maximum possible speed.

[0051] For example, the electric motor 11Since it is powered by a DC voltage, the control logic can be expected to use a PWM (pulse width modulation) modulated signal. The DC voltage used may depend on the application area of ​​the particle extraction system, for example 12 Volts on conventional motor vehicles, 24 Volts on heavy or industrial vehicles such as trucks or buses, or 72 Volts on railway equipment (trams, trains).

[0052] It should be noted here that, instead of a suction turbine, the source of vacuum may be pre-existing on the vehicle. In the automotive sector, this could be a vacuum generated by the engine's operation, for example, by bypassing the air intake, or, as another example, by using a Venturi effect on an outgoing gas flow, such as exhaust gases. In the railway sector, the source of vacuum may be derived from the pneumatic braking system or other auxiliary equipment of the railway vehicle in question.

[0053] Depending on the configuration, the target vacuum value is selected within a range of 20 to 100 millibars below ambient pressure. In other words, on the absolute pressure scale, the absolute pressure setpoint in the first duct can be 90% to 98% of the atmospheric pressure prevailing near the suction system. Sensor 22 can be used to control the turbine's rotational speed setpoint, thus ensuring it rotates only when necessary.

[0054] Advantageously, a means is planned 60 providing information on the ongoing activation of braking.

[0055] In certain road vehicle configurations, there is simply a binary on / off switch interacting with the brake pedal. 68. This switch can deliver information 67 directly to the control unit 6 of the suction system or via a control unit63 of the braking function for example the one that manages the ABS function.

[0056] In another configuration, richer information, either analog or digital, can be provided, precisely reflecting the current position of the brake pedal, which allows the control unit 6 to know, on the one hand, the braking intensity and, on the other hand, to be able to react very early, as soon as the user or driver begins to apply the brake pedal. In this case, a potentiometer is provided. 69 analog or digital, which delivers rich information 66 to the control unit 6 of the suction system.

[0057] Note that if the road vehicle is equipped with driver assistance systems including autonomous driving or an emergency braking function, braking may be activated without the pedal actually being pressed; in this case, a computer processes and sends the information to the control unit. 6 of the suction system.

[0058] The control unit 6 It therefore has at its disposal information on the activation of braking in progress, either binary or more elaborate.

[0059] In another context, such as a railway setting, the information indicating that braking is currently being activated can originate from the brake actuator that controls the aforementioned friction braking system. The brake actuator can be a joystick. Here too, braking can occur without any action on the joystick; in this case, a computer processes and sends the information to the control unit. 6of the suction system.

[0060] Furthermore, control unit 6 receives information regarding the vehicle's current speed. This current vehicle speed information can be provided by the braking control unit. 63 or by any other identified computer 96 to the figure 4 .

[0061] Vehicle speed information can be received via a wired connection or a data bus connection. A CAN or J1939 bus can be used for a road vehicle.

[0062] The "vehicle speed" information is received on a regular basis, e.g., refreshed in near real-time. For example, a refresh rate of at least 10 times per second can be expected.

[0063] On the figure 4 We illustrated a diagnostic arrangement 4, which allows a diagnostic tool to communicate with the control unit 6. The diagnostic layout4 includes a diagnostic tool 41, a sheet 43 permanently attached to the vehicle, a counter-brace 42 related to the diagnostic tool 41 which allows the latter to be temporarily connected to the vehicle's computers. Diagnostic dialogue messages can, if necessary, be transmitted via a communication gateway. 44.

[0064] The diagnostic tool 41 can be connected wirelessly, in 'wireless' mode. The control unit 6 It is electrically powered by a direct current supply from the vehicle. However, battery power is not excluded. Functioning

[0065] There figure 6 illustrates a chronogram on a first time scale (typically several tens of minutes or a few hours), while the figure 7 illustrates a chronogram on a second, longer time scale, several hours or several days.

[0066] First, we notice that, generally speaking, while driving, as soon as braking is activated (top of the chronograph of the figure 6 ), the control unit 6 commands the turbine for a braking suction sequence 51.

[0067] In other words, a braking suction sequence 51 is implemented based on the current braking activation information, to ensure suction as soon as braking is activated and as long as braking is activated, provided that the vehicle is moving.

[0068] As an exception, if the vehicle speed is zero, the control unit 6 may refrain from ordering the turbine.

[0069] During driving, all braking and slipstreaming sequences 51 is spotted eight usually 5 on the figure 6 , and the particles that pass through the pneumatic pipe3 Some particles can be deposited there during the suction phases. It is noted that the durations of the braking suction sequences, triggered at the moments T1, T2 and following, are highly variable, they depend in particular on the duration of brake activation.

[0070] Advantageously, according to the present proposal, a cleaning suction sequence is planned to be carried out independently of any braking activation. SeqN also known as the cleaning sequence 52 intended to clean the pneumatic pipe 3.30. The turbine is controlled by the control unit 6 at maximum possible power. The cleaning command is applied for a predetermined duration. TN. TN is chosen from a range between 3 seconds and 15 seconds. For example, we can choose TN = 5 seconds, or TN = 8 seconds, or TN = 10 seconds.

[0071] The conditions for triggering a cleaning sequence will be discussed below.

[0072] Note that the cleaning sequence is performed when the pad is not firmly pressed against the disc. As illustrated in the figure 8 , outside of braking action, the brake pad 19 is not applied firmly against the disc 9. In practice, when not braking, a small free gap of width is observed. E (whose size has been intentionally exaggerated on the figures 8 and 9 ). In the case of a railway brake, this free space can be a little larger.

[0073] In the case of suction ports in the brake pads, the presence of this free space creates a passage for air. The limiting cross-section from an aerodynamic point of view is therefore larger than when the pad is firmly pressed against the disc.

[0074] Indeed, when the brake pad is firmly pressed against the disc, the limiting cross-section from an aerodynamic perspective is determined by the groove(s) in the pad, which are small even if there is an air intake vent. Brake suction sequences occur primarily when the pad is firmly pressed against the disc, so these sequences are performed at low airflow due to the small limiting cross-section.

[0075] Conversely, thanks to the aforementioned free gap, when the brake pad is not firmly pressed against the disc, the cleaning sequences are performed with a high airflow. This facilitates the removal of particles that may have accumulated on the internal walls of the pneumatic line. A cleaning sequence keeps the internal walls of the pneumatic line intact. Thus, even after a long service life of several years and / or several hundred thousand kilometers driven, the pneumatic line(s) do not become significantly clogged.

[0076] Determining the cleaning suction condition is a logical / algorithmic calculation taking into account one or more of the arguments that are set out below.

[0077] The vehicle's current speed is a key factor. While driving, a cleaning sequence is not triggered if the vehicle's speed is too high. VV is below a first speed threshold V1 We can choose. V1 = 70 km / h. As an alternative, one can choose V1 = 50 km / h.

[0078] Furthermore, the distance traveled since the last cleaning sequence is taken into account. For example, a cleaning sequence is triggered after the vehicle has traveled DD1 = 50 km since the last cleaning sequence. In other words, after a cleaning sequence, the control unit 6 refrains from ordering a new cleaning sequence for the next DD1 kilometers, DD1 being a predetermined threshold. The distance traveled DDdoes not need to be known precisely. The distance traveled can be obtained by integrating the vehicle speed. Alternatively, it can be received from another computer, for example, the dashboard.

[0079] The number of dynamic braking events performed since the last cleaning sequence is taken into account. For example, a cleaning sequence is triggered after N1 Suction sequences are performed on the vehicle. A value between 50 and 200 can be chosen for N1, for example N1 = 100.

[0080] Instead of a simple number of braking maneuvers, a cumulative braking score can be calculated. SCF, where a weight is applied to each braking event. The more violent the braking, the greater the weight. The braking power can be deduced from the velocity gradient (the decrease in velocity over time).

[0081] We can choose as a criterion to trigger a cleaning sequence the criterion defined by the logic: [ SCF > SCF1 or DD > DD1 ] and VV > VV1.

[0082] The time elapsed since the last cleaning sequence is taken into account. For example, a cleaning sequence is triggered after N2 days have passed. N2 can be a value between 10 and 30 days.

[0083] As illustrated in the figure 7 , A cleaning sequence has just been triggered. T21 while the speed is higher V1 After a certain period of time, which can be quite long given the criteria mentioned above, another cleaning sequence will be performed. T22, here too, when the vehicle's speed is greater than V1 .

[0084] A cleaning sequence can also be used during a maintenance phase. In this case, the cleaning sequence 52is triggered in response to a request made by a diagnostic device 41.

[0085] Here we are interested in the operation of replacing brake pads, for example during a maintenance operation in a garage.

[0086] Generally the vehicle is not moving, and the internal combustion engine is not running.

[0087] The control unit 6 The system receives an ad-hoc diagnostic request from the diagnostic tool and commands the turbine to maximum speed during the cleaning sequence prescribed by the diagnostic request. The duration can be TN or shorter. The TN duration can be a parameter of the diagnostic request. Note that the mechanic can receive audible feedback of the turbine's rotation to verify its proper operation.

[0088] As illustrated in the figure 9 , Optionally, a solenoid valve for venting to the atmosphere can be provided. 59fluidly connected to the pneumatic circuit and close to the suction inlet. Such a solenoid valve makes it possible to substantially increase the airflow inside the pneumatic line during the cleaning sequence.

[0089] The control unit 6 can be configured to control, during the cleaning sequence, a solenoid valve for venting to the atmosphere 59 arranged on the pneumatic circuit near the suction inlet.

[0090] On the figure 4 The option of this solenoid valve for venting to the atmosphere was represented. 59 controlled by the control unit 6.

Claims

1. Method for controlling a braking particle suction system of a friction braking system, the suction system comprising: at least one negative pressure source (1), at least one suction mouth (83) arranged close to a friction interface or inside a friction part and connected by at least one pneumatic line to the negative pressure source, a control unit (6) configured to control the negative pressure source, and a means of supplying current braking activation information, the method providing that the control unit is configured to: a- control the negative pressure source, for a braking suction sequence (51), according to the current braking activation information, in order to ensure suction is applied as soon as braking is activated, b- establish at least one cleaning suction condition, outside of the braking sequences, c- as soon as the at least one cleaning suction condition satisfies a predetermined criterion, control the negative pressure source for a cleaning sequence (52) for the at least one pneumatic line, for a predetermined duration (TN), the method providing that, in step b-, the determination of the cleaning suction condition is a logical / algorithmic calculation which takes into account at least one of the following variables: - the current speed of the vehicle, in particular above a first speed threshold (V1), - the time elapsed since the last cleaning sequence, - the distance traveled since the last cleaning sequence, - the number of dynamic braking actions carried out since the last cleaning sequence, - the prevalence of a maintenance mode.

2. Method according to claim 1, wherein the cleaning sequence is triggered, outside of maintenance mode, only if the current speed of the vehicle is greater than the first speed threshold (V1).

3. Method according to one of claims 1 to 2, wherein, in step c-, the negative pressure source is activated to maximum power.

4. Method according to one of claims 1 to 3, wherein the predetermined duration (TN) is selected within a range of between 3 seconds and 15 seconds.

5. Method according to claim 2, wherein the first speed threshold (V1) is greater than 50 km / h and preferably equal to 70 km / h.

6. Method according to one of claims 1 to 5, wherein the cleaning sequence (52) is triggered in response to a request made by a diagnostic device during maintenance mode.

7. Method according to one of claims 1 to 6, wherein the negative pressure source is formed by a turbine driven by an electric motor (11), the control unit (6) being configured to control the electric motor.

8. Method according to one of claims 1 to 6, wherein the control unit (6) is configured to control, during the cleaning sequence, a vent solenoid valve (59) arranged on the pneumatic circuit close to the suction mouth.

9. Braking particle suction system of a friction braking system, the suction system comprising at least one negative pressure source (1), at least one suction mouth (83) arranged close to a friction interface or inside a friction part and connected by at least one pneumatic line to the negative pressure source, a control unit (6) configured to control the negative pressure source, and a means of supplying current braking activation information, the suction system being configured to implement the method according to one of the preceding claims.

10. System according to claim 9, further comprising at least one filter (2) for collecting the suctioned particles.

11. System according to one of claims 9 to 10, wherein the system comprises a centralized filter and a centralized turbine, which are connected to four or more suction mouths.

12. System according to one of claims 9 to 11, wherein a vent solenoid valve (59) is provided on the pneumatic circuit and close to the suction mouth.