Brake system and related brake system control method

Abstract

A method of controlling a braking system (1) of a vehicle to activate a parking brake actuated by the braking system (1), comprising the steps of: bringing a first actuator (2) close to a first pad to apply a first force (Fa); bringing a second actuator (3) close to a second pad to apply a second force (Fb); bringing a second actuator (3) close to the second pad to apply the second force (Fb); detecting values ​​of the first force (Fa) and the second force (Fb); synchronizing the application of the first force (Fa) and the second force (Fb) to a brake disc; continuing to operate the first actuator (2) and the second actuator (3) until the first force (Fa) reaches a first force value (F1) and the second force (Fb) reaches a second force value (F2); and stopping the first actuator (2) and the second actuator (3) by an electronic processing unit (4).

Description

[Technical field]

[0001] FIELD OF THEINVENTION

[0002] The invention particularly relates to a method for controlling a braking system of a vehicle and to a braking system of a vehicle. [Background technology]

[0003] Background technology

[0004] Passenger cars, and generally any vehicle with two or more wheels intended for the transport of passengers on roads, are equipped with a hand parking brake, the function of which is to lock the wheels of the vehicle to prevent movement of the vehicle when parked.

[0005] In modern braking systems, for example those equipped with Electronic Brake-by-Wire (BBW) technology, the hand parking brake is replaced by an Electric Parking Brake (EPB).

[0006] From every perspective, the EPB electric parking brake can be considered a subsystem of the electronic brake system with BBW technology used for the service brakes.

[0007] More specifically, the EPB subsystem allows the driver to activate the wheel locking mechanism through an appropriate button or other actuator, or through other automatic functions managed by the electronic processing unit, such as signal logic related to the ignition key, gear engagement, accelerator pedal, etc. When these devices are activated, a request to activate the parking brake is sent to the vehicle's electronic control unit, which electrically activates the brake pads to lock the brake discs and stop the vehicle from moving.

[0008] Conversely, upon restart, the driver activates the actuator, thereby sending a parking brake release request to the vehicle's electronic control unit, which then electrically activates the brake pads to unlock the brake discs and allow movement of the vehicle.

[0009] Furthermore, in addition to replacing the parking brake function traditionally performed by a manual parking brake, the EPB subsystem is configured to provide automatic functions to assist the driver, such as the so-called "auto-hold" function, i.e. the automatic locking of the wheels without driver request when the vehicle is stationary, e.g. on an uphill slope, and the unlocking as soon as the driver presses the vehicle's accelerator pedal.

[0010] In known disc brakes with fixed brake calipers, two pads facing the brake disc are actuated by respective pistons which are independently actuatable by at least two actuators, at least one of which is arranged on either side of the brake disc.

[0011] At least two opposing actuators are independently controlled by an electronic control unit and are therefore simultaneously and independently operable and controllable from one another.

[0012] For each of the two actuators, the actuation of the parking brake according to known control logic can be divided into three successive steps:

[0013] Penetration step: The penetration step is the time from when the electronic control unit commands the actuator, which is placed at a predetermined starting position, to start moving to when the actuator starts moving without applying any braking force to the corresponding pad.

[0014] Approach Step: The approach step is the time between when the actuator starts moving without applying any braking force to the corresponding pad, and when the actuator contacts the pad and starts applying a braking force to the pad.

[0015] Application Step: The application step lasts from the moment the actuator applies and increases the braking force on the pads until the moment the braking force applied by the actuator on the pads reaches a certain predefined reference value.

[0016] In known control logic, at least two opposing actuators are configured to simultaneously initiate the entry step of the parking brake application process in order to initiate the axial thrust acting on two opposing faces of the brake disc as symmetrically as possible.

[0017] Such symmetry is necessary to minimize the stresses acting on the brake disc, which may reduce the likelihood of the brake disc cracking, damaging or rupturing.

[0018] In known disc brakes having at least two individually controllable opposing actuators, wear and deterioration of mechanical parts and uncertainties associated with the starting positions of the two opposing actuators can cause differences in the application of braking forces by these two actuators, in particular differences in the times it takes the two actuators to approach their respective pads and apply their respective braking forces, resulting in differences in the duration of the approach step.

[0019] If the duration of the approach step of one actuator differs from the duration of the approach step of the opposing actuator, the two actuators cannot begin to apply braking force at the same time and undesirable and harmful asymmetric axial thrust forces will act on the brake disc. Summary of the Invention

[0020] solution

[0021] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a method for controlling a brake system and a brake system which overcomes at least some of the drawbacks of the prior art.

[0022] A particular object of the present invention is to provide a method and system for controlling a braking system which minimizes asymmetric axial thrust forces acting on the brake discs during application of the parking brakes.

[0023] Moreover, a particular object of the present invention is to provide a method for controlling a braking system and a braking system adapted to execute the control method in a simplified manner and with reduced energy and structural constraints.

[0024] These and other objects are achieved by a method for controlling a braking system and a braking system according to the independent claims.

[0025] The dependent claims relate to preferred and advantageous embodiments of the invention. [Brief description of the drawings]

[0026] drawing

[0027] In order that the invention may be better understood and its advantages appreciated, non-limiting exemplary embodiments thereof will now be described with reference to the accompanying drawings, in which: FIG.

[0028] [Figure 1] FIG. 1 shows a schematic diagram of a braking system according to an embodiment of the present invention.

[0029] [Diagram 2] FIG. 2 illustrates the supply currents to the actuators of a braking system and the respective forces acting on the pads of the same braking system, according to one embodiment of the present invention.

[0030] [Diagram 3]FIG. 3 illustrates the supply currents and respective forces to two individually controllable actuators of a brake caliper of a braking system according to the prior art.

[0031] [Figure 4] FIG. 4 shows diagrammatically the supply currents and respective forces actuated by two individually controllable actuators of a brake caliper of a braking system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Description of the Preferred Embodiments

[0033] A method for controlling a vehicle brake system 1 to apply a parking brake force applied by the brake system 1 will now be described with reference to the drawings.

[0034] The brake system 1 is of a type which includes at least the following:

[0035] Brake discs;

[0036] a first pad and a second pad spaced apart from each other and positioned to face the brake disc;

[0037] a first actuator 2 configured to apply a first force Fa to the first pad and release the force to move the first pad from an open position in which the first pad is away from the brake disc and no parking brake force is applied to a closed position in which the first pad is pressed against the brake disc and the parking brake force is applied;

[0038] a second actuator 3 configured to apply a second force Fb to the second pad to move the second pad from an open position in which the second pad is spaced from the brake disc and does not apply a braking force to a closed position in which the second pad applies a force to the brake disc to apply a parking brake force;

[0039] an electronic processing unit 4 configured to control the actuation of the first actuator 2 and the second actuator 3; and

[0040] Detection means operably connected to the electronic processing unit 4 and configured to directly or indirectly detect the value of a first force Fa applied to the first pad by the first actuator 2 and to directly or indirectly detect the value of a second force Fb applied to the second pad by the second actuator 3.

[0041] The method includes the following steps.

[0042] a step of bringing the first actuator 2 closer to the first pad to apply a first force Fa and increasing the value of the first force Fa, and bringing the second actuator 3 closer to the second pad to apply a second force Fb and increasing the value of the second force Fb, by the electronic processing unit 4;

[0043] detecting values ​​of the first force Fa and the second force Fb by a detection means during operation of the first actuator 2 and the second actuator 3;

[0044] synchronising, by the electronic processing unit 4, the application of the first force Fa and the second force Fb to the brake disc;

[0045] continuing to operate the first actuator 2 and the second actuator 3 until a first force value F1 is reached by the first force Fa and a second force value F2 is reached by the second force Fb;

[0046] Stopping the first actuator 2 and the second actuator 3 by the electronic processing unit 4 .

[0047] Furthermore, synchronizing the application of the first force Fa and the second force Fb to the brake disc comprises the following steps:

[0048] at a first time t1 when the detection means detects that the first force Fa has increased to a value substantially exceeding the third force value F3, stopping the first actuator 2 and continuing to operate the second actuator 3;

[0049] activating the first actuator 2 at a second time t2 when the detection means detects that the second actuator 3 is applying a second force Fb substantially greater than the fourth force value F4.

[0050] Alternatively, the step of synchronizing the application of the first force Fa and the second force Fb to the brake disc comprises the following steps.

[0051] at a first time t1 when the detection means detects that the second force Fa has increased to a value substantially exceeding the fourth force value F4, stopping the second actuator 3 and continuing to operate the first actuator 2;

[0052] activating the second actuator 3 at a second time t2 when the detection means detects that the first actuator 2 is applying the first force Fb with a value substantially greater than the third force value F3.

[0053] Advantageously, the control method according to the present invention minimizes the asymmetric axial thrust acting on the brake disc during application of the parking brake.

[0054] This is achieved by synchronizing the application of the first and second forces Fa, Fb to the two sides of the brake disc. This synchronization is achieved by sharing information between the two actuators via an electronic processing unit when one of the actuators detects contact with its corresponding pad. As a result, the actuator that detects contact is temporarily stopped and waits until the other actuator next detects contact with its corresponding pad.

[0055] As can be seen by comparing Figures 6 and 7 (showing the control method according to the invention) with Figures 4 and 5 (showing the control method according to the prior art), the method according to the invention significantly reduces the asymmetric axial thrust acting on the brake disc, i.e. reduces the difference in the opposing forces applied by each actuator at the completion of parking brake application.

[0056] Advantageously, the control method according to the invention is applicable to braking systems comprising at least one fixed brake caliper.

[0057] According to an embodiment of the present invention, the third value F3 is substantially equal to the fourth force value F4.

[0058] According to an embodiment of the present invention, the third force value F3 is equal to zero.

[0059] According to one embodiment, the fourth force value F4 is equal to zero.

[0060] According to one embodiment, the third force value F3 and the fourth force value F4 are both equal to zero.

[0061] According to one embodiment of the present invention, the first force value F1 and the second force value F2 are greater than the third force value F3 and the fourth force value F4.

[0062] Furthermore, the first force value F1 and the second force value F2 are equal to force values ​​that complete the application of the parking brake.

[0063] According to one embodiment of the present invention, the first force value F1 is substantially equal to the second force value F2.

[0064] According to one embodiment of the present invention, the step of detecting the value of the first force Fa by the detection means includes the following steps.

[0065] detecting an angular position of the first actuator 2 by a detection means;

[0066] calculating by the electronic processing unit 4 a value of the first force Fa based on the angular position of the first actuator 2; or

[0067] detecting the value of a first supply current i a supplied to the first actuator 2; and

[0068] calculating by the electronic processing unit 4 a value of the first force Fa based on a value of the first supply current i a supplied to the first actuator 2;

[0069] According to one embodiment, the step of detecting the value of the second force Fb by means of a detection means comprises the following steps:

[0070] detecting the angular position of the second actuator 3 by means of a detection means; and

[0071] calculating, by the electronic processing unit 4, a value of the second force Fb based on the angular position of the second actuator 3; or

[0072] detecting a value of a second supply current ib supplied to the second actuator 3; and

[0073] Calculating by the electronic processing unit 4 a value of the second force Fb based on the value of the second supply current ib supplied to the second actuator 3.

[0074] According to one embodiment of the present invention, the steps of moving the first actuator 2 toward the first pad to apply a first force Fa and increasing the value of the first force Fa and moving the second actuator 3 toward the second pad to apply a second force Fb and increasing the value of the second force Fb by the electronic processing unit 4 are activated when the electronic processing unit 4 receives a parking brake force application request signal.

[0075] The parking brake force application request signal is transmitted by an actuator operably connected to the electronic processing unit 4 when the actuator is actuated.

[0076] The actuator is operable by a user.

[0077] According to an embodiment of the present invention, the method includes, after the step of continuing to operate the first actuator 2 and the second actuator 3 until a first force value F1 is reached by a first force Fa and a second force value F2 is reached by a second force Fb, the following steps:

[0078] transmitting a complete parking brake force application signal from the electronic processing unit 4 to a signaling device operatively connected to the electronic processing unit 4.

[0079] Optionally, the complete parking brake force application signal is visible to the user by a signaling device.

[0080] According to one embodiment, the step of synchronizing the application of the first force Fa and the second force Fb to the brake disc is performed iteratively, preferably with a repetition time of 5-10 milliseconds.

[0081] According to one embodiment, during the step of synchronizing the application of the first force Fa and the second force Fb to the brake disc, the value of the first force Fa and / or the value of the second force Fb are detected every 5-10 milliseconds.

[0082] According to a further aspect of the invention, a vehicle brake system 1 configured to apply a parking brake force includes at least the following features:

[0083] Brake discs;

[0084] a first pad and a second pad spaced apart from each other and positioned opposite the brake disc;

[0085] a first actuator 2 configured to apply a first force Fa to the first pad and release the force to move the first pad from an open position in which the first pad is away from the brake disc and does not apply the parking brake force to a closed position in which the first pad is biased against the brake disc and applies the parking brake force;

[0086] a second actuator 3 configured to apply a second force Fb to the second pad to move the second pad from an open position in which the first pad is away from the brake disc and does not apply a braking force to a closed position in which the second pad is biased against the brake disc and applies a parking brake force;

[0087] an electronic processing unit 4 configured to control the actuation of the first actuator 2 and the second actuator 3;

[0088] Detection means operably connected to the electronic processing unit 4 and configured to directly or indirectly detect the value of a first force Fa applied to the first pad by the first actuator 2 and to directly or indirectly detect the value of a second force Fb applied to the second pad by the second actuator 3.

[0089] The brake system 1 is configured to apply a parking brake force by carrying out the method described above.

[0090] Advantageously, the brake system 1 configured in this way makes it possible to minimize the asymmetric axial thrust acting on the brake discs when applying the parking brake.

[0091] Further advantageously, the brake system 1 configured in this way reduces energy and structural constraints.

[0092] Advantageously, the braking system comprises at least one fixed brake caliper.

[0093] According to an embodiment of the present invention, the braking system 1 comprises an actuator operatively connected to an electronic processing unit 4 .

[0094] The electronic processing unit 4 is configured to operate both the first actuator 2, which approaches the first pad to apply a first force Fa and increase the value of the first force Fa, and the second actuator 3, which approaches the second pad to apply a second force Fb and increase the value of the second force Fb, when the electronic processing unit 4 receives a parking brake actuation request signal.

[0095] A parking brake application request signal is transmitted by an actuator when the button is actuated.

[0096] The actuator is operable by a user.

[0097] Advantageously, the actuator may be located within the vehicle passenger compartment close to the position occupied by a user.

[0098] The actuator may for example be a suitable button, an ignition key, a gear shift actuator, an accelerator pedal or another pedal, or a device connected to an automatic function managed by the electronic processing unit 4 or a suitable electronic processing unit.

[0099] According to one embodiment, the brake 1 comprises a signalling device operatively connected to the electronic processing unit 4 .

[0100] The electronic processing unit 4 is arranged to transmit a complete parking brake application signal to a signalling device.

[0101] The parking brake application signal is visible to the user by a signaling device.

[0102] The signaling device may for example be a warning light or a digital screen placed in the passenger compartment of the vehicle close to where the user is located.

[0103] According to one embodiment, the detection means comprise an angular position detector, preferably an encoder, arranged to detect the angular position of the first actuator 2 and / or the second actuator 3 .

[0104] Alternatively or additionally, the detection means comprises a current detector, preferably an ammeter, configured to detect the value of the supply current supplied to either the first actuator 2 or the second actuator 3 .

[0105] The electronic processing unit 4 comprises a calculator configured to calculate a value of the first force Fa and / or the second force Fb based on the angular position of the first actuator 2 or the second actuator 3, respectively.

[0106] Alternatively or additionally, the calculator is configured to calculate values ​​of the first force Fa and / or the second force Fb based on the value of the supply current supplied to the first actuator 2 or the second actuator 3, respectively.

[0107] It will be apparent to one skilled in the art that changes and modifications can be made to the present invention without departing from the scope of the claims that follow. [Explanation of symbols]

[0108] 1. Brake system 2. First actuator 3. Second Actuator 4. Electronic Processing Unit Fa. The First Power Fb. The second power F1. First force value F2. Second force value F3. The third force value F4. Fourth force value ia. 1st supply current ib. 2nd supply current t1. Time 1 t2. The second time point

Claims

1. activating a parking brake force applied by the vehicle's brake system (1); A method for controlling a braking system (1) of a vehicle, comprising: The brake system (1) comprises at least Brake discs and a first pad and a second pad spaced apart on either side of the brake disc; a first actuator (2) configured to apply or release a first force (Fa) to the at least one first pad to move the first pad from an open position in which the at least one first pad is spaced from the first brake disc and does not apply the parking brake force to a closed position in which the first pad presses against the brake disc and applies a braking force; a second actuator (3) configured to apply a second braking force (Fb) to the second pad to move the second pad from an open position in which the second pad is spaced from the brake disc and does not apply a braking force to a closed position in which the second pad is pressed against the brake disc and applies a braking force; and an electronic processing unit (4) configured to control the operation of the first actuator (2) and the second actuator (3); detection means operatively connected to the electronic processing unit (4) and configured to directly or indirectly detect a value of the first braking force (Fa) applied to the first pad by the first actuator (2) and to directly or indirectly detect a value of the second braking force (Fb) applied to the second pad by the second actuator (3); The method comprises: activating the first actuator (2) by the electronic processing unit (4) to move the first actuator (2) closer to the first pad to apply the first force (Fa) and increase the value of the first force (Fa), and activating the second actuator (39) to move the second actuator (3) closer to the second pad to apply the second force (Fb) and increase the value of the second force (Fb); detecting values ​​of the first force (Fa) and the second force (Fb) by the detection means during operation of the first actuator (2) and the second actuator (3); synchronising the application of said first force (Fa) and said second force (Fb) to said brake disc by said electronic processing unit (4); continuing the operation of the first actuator (2) and the second actuator (3) until the first force (F1) is achieved by the first force (Fa) and the second force (F2) is achieved by the second force (Fb); and stopping, by the electronic processing unit, the first actuator (2) and the second actuator (3); The step of synchronizing the application of the first force (Fa) and the second force (Fb) to the brake disc comprises: stopping the first actuator (2) and continuing to operate the second actuator (3) at a first time point (t1) when the detection means detects that the first force (Fa) has increased to a value substantially exceeding a third force value (F3); and activating the first actuator (2) at a second time point (t2) when the detection means detects that the second actuator (3) is applying a second force (Fb) with a force substantially exceeding a fourth force value (F4). Or, at a first time point (t1) when the detection means detects that the second force (Fa) has increased to a value substantially greater than a fourth force value (F4), stopping the second actuator (3) and continuing to operate the first actuator (2); and at a second time point (t2) when the detection means detects that the first actuator (2) is exerting a first force (Fb) substantially greater than a third force value (F3), activating the second actuator (3).

2. The method of claim 1 , wherein the third force value (F3) is substantially equal to the fourth force (F4).

3. 3. The method according to claim 1 or 2, wherein the third force value (F3) is zero and / or the fourth force value (F4) is zero.

4. the first force value (F1) and the second force value (F2) are greater than the third force value (F3) and the fourth force value (F4); 4. The method according to claim 1, wherein the first force (value F1) and the second force value (F2) are equal to a force value large enough to complete application of a parking brake force.

5. The method of claim 4, wherein the first force value (F1) is substantially equal to the second force value (F2).

6. The step of detecting the value of the first force (Fa) by the detection means includes: detecting an angular position of the first actuator (2) by said detection means and calculating by said electronic processing unit (4) a value of the first force (Fa) from said angular position of the first actuator (2); Or, detecting a value of a first supply current (ia) supplying power to the at least one first actuator (2); and calculating, by the electronic processing unit (4), a value of the first force (Fa) based on the value of the first supply current (ia) supplying power to the first actuator (2). and / or The step of detecting the second force (Fb) by the detection means includes: detecting an angular position of the second actuator (3) by said detection means and calculating by said electronic processing unit (4) a value of the second force (Fb) from said angular position of the second actuator (3); Or, The method according to any one of claims 1 to 5, comprising one of the steps of detecting a value of a second supply current (ib) supplying power to the at least one second actuator (3) and calculating, by the electronic processing unit (4), a value of the second force (Fb) based on the value of the second supply current (ib) supplying power to the second actuator (3).

7. the step of activating the first actuator (2) to move closer to the first pad and apply and increase the first force (Fa) and the step of activating the second actuator (3) to move closer to the second pad and apply and increase the second force (Fb) by the electronic processing unit (4) is executed when the electronic processing unit (4) receives a parking brake force actuation signal; The method according to any one of claims 1 to 6, wherein the parking brake force application request signal is transmitted by a user operable actuator in operative connection with the electronic processing unit (4) when the actuator is actuated.

8. after continuing to operate the first actuator (2) and the second actuator (3) until the first force (Fa) reaches a first force value (F1) and the second force (Fb) reaches a second force value (F2); transmitting a parking brake force complete activation signal from said electronic processing unit (4) to a signaling device operatively connected to said electronic processing unit (4); A method according to any one of claims 1 to 7, wherein the parking brake force complete application signal is visible to a user by means of the signalling device.

9. 9. The method according to claim 1, wherein during the step of synchronizing the application of the first force (Fa) and the second force (Fb) to the brake disc, a value of the first force (Fa) and / or a value of the second force (Fb) are detected every 5-10 milliseconds.

10. A vehicle brake system (1) configured to apply a parking brake force, the brake system (1) comprising at least Brake discs; a first pad and a second pad disposed on either side of the brake disc in a spaced relationship; a first actuator (2) configured to apply and release a first force (Fa) to at least one first pad to move the first pad from an open position, in which the first pad is spaced from the first brake disc and no parking brake force is applied, to a closed position, in which the first pad is pressed against the brake disc and a parking brake force is applied; a second actuator (3) configured to apply a second braking force (Fb) to the second pad to move the second pad from an open position in which the second pad is away from the brake disc and does not apply a braking force to a closed position in which the second pad is pressed against the brake disc and applies a parking brake force; an electronic processing unit (4) configured to control the operation of the first actuator (2) and the second actuator (3); detection means operatively connected to the electronic processing unit (4) and configured to directly or indirectly detect a value of the first braking force (Fa) exerted by the first actuator (2) on the first pad and to directly or indirectly detect a value of the second braking force (Fb) exerted by the second actuator (3) on the second pad, The brake system (1), configured to apply a parking brake force by performing a method according to any one of claims 1 to 9.

11. an actuator operatively connected to said electronic processing unit (4); an electronic processing unit (4) configured to, upon receiving a parking brake force actuation signal, operate both a first actuator (2) to approach a first pad to apply a first force (Fa) and a second actuator (3) to approach a second pad to apply a second force (Fb); When the electronic processing unit (4) receives a parking brake force actuation signal, the electronic processing unit (4) actuates the first actuator (2) to move closer to the first pad and apply and increase the first force (Fa), and actuates the second actuator (3) to move closer to the second pad and apply and increase the second force (Fb); the parking brake force application request signal is transmitted by the actuator when the actuator is actuated; The actuator is operable by a user. and / or The braking system (1) includes a signaling device operatively connected to the electronic processing unit (4); The electronic processing unit (4) is configured to transmit a parking brake complete application signal to a signaling device, 11. The system (1) of claim 10, wherein the parking brake force application signal is visible to a user by means of the signaling device.

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