FR3145529A1 - BRAKE BACK-UP CIRCUIT TRANSMITTING A SIGNAL REPRESENTATIVE OF WHEEL SPEED TO A BRAKE CONTROL UNIT - Google Patents

Abstract

The invention relates to a brake for a wheel of a motor vehicle. The brake comprises a local control unit (17) which is configured to control the braking of the wheel. According to the invention, the brake comprises a backup analog circuit (5) which is configured to transmit a signal representative of a detected rotational speed of the wheel to the local control unit (17), when a failure of a braking data transmission network is detected and/or when a failure of a central control unit (12) of the braking system of the motor vehicle is detected. Figure 3

Description

BRAKE BACK-UP CIRCUIT TRANSMITTING A SIGNAL REPRESENTATIVE OF WHEEL SPEED TO A BRAKE CONTROL UNIT

The invention relates to braking systems for motor vehicles. More specifically, the invention relates to detecting the speed of a wheel of a motor vehicle during an operating anomaly of a data transmission network of a braking system and/or an operating anomaly of a central control unit of a braking system.

The invention also relates to a control of a motorized vehicle brake based on the detection of a rotation speed of the wheel which is intended to be braked by the brake.

STATE OF THE PRIOR ART

A motor vehicle braking system comprises a brake for each of the vehicle's wheels, a central control unit for controlling the brakes, and rotational speed sensors for each of the wheels of the motor vehicle. The central control unit is, for example, a control unit for an electronic trajectory corrector and/or an anti-lock device for the wheels of the vehicle.

The braking system includes a data transmission network which is configured to transmit a signal representative of the detected rotational speed of each of the wheels to the central control unit.

If the central control unit fails to process the rotational speed detection signal of at least one of the wheels and/or if a vehicle data transmission network fails to transmit the detected rotational speed signal of the wheel, a brake control system does not issue a brake command based on the detected rotational speed of each of the vehicle's wheels. The vehicle's wheels are more likely to lock, electronic steering correction is limited, and the vehicle's steering tends to be less precise.

There is a need to limit or even prevent wheel lock of the motor vehicle, to improve the electronic trajectory correction of the motor vehicle, and/or to improve the precision of the trajectory of the motor vehicle, in the event of failure of a central control unit of the braking system and/or of a data transmission network of the motor vehicle.

In this regard, the invention relates to a brake for a motor vehicle wheel. The brake comprises a local control unit which is configured to control the braking of the wheel.

According to the invention, the brake comprises a backup analog circuit which is configured to transmit a signal representative of a detected rotation speed of the wheel to the local control unit, when a failure of a data transmission network is detected and/or when a failure of a central control unit of the braking system of the motor vehicle is detected.

By means of the invention, wheel locking tends to be at least limited, if not prevented, in the event of a failure of the central control unit of a braking system and/or a data transmission network of the motor vehicle. In particular, the local brake control unit controls, for example, the wheel brake, in order to prevent the wheel from locking, by at least partially ensuring the function of an anti-lock braking device in emergency operation.

The speed of the vehicle and/or the trajectory of the vehicle may be detected, from the signal representing the detected rotational speed of each of the wheels, in the event of a failure of the central control unit of a braking system and/or of a data transmission network of the motor vehicle. In particular, the local brake control unit detects, for example, the speed of the vehicle and/or the trajectory of the vehicle, by at least partially ensuring the function of a computer of a detection system in emergency operation.

The control of the vehicle speed and/or the trajectory of the motorized vehicle tends to be improved, for example by controlling the speed of each of the wheels from the signal representing the detected rotational speed of each of the wheels, in the event of a failure of the central control unit of a braking system and/or of a data transmission network of the motorized vehicle. In particular, the local brake control unit controls, for example, the vehicle speed and/or the trajectory of the vehicle, by at least partially ensuring the function of an electronic trajectory corrector of the vehicle in emergency operation.

The local control unit and/or the central control unit includes in particular a computer such as a microcontroller or a microprocessor.

Central control unit failure is for example a failure of the central control unit to process the wheel rotation speed detection signal, including signal conditioning.

The failure of the vehicle data transmission network is, for example, a failure of the data transmission network to transmit a wheel rotation speed detection signal to the central control unit.

The invention may optionally comprise one or more of the following features, combined with each other or not.

According to a particular embodiment, the backup analog circuit is configured to transmit the signal representative of the detected rotation speed of the wheel to the local control unit, when a failure of the data transmission network for transmitting a wheel rotation speed detection signal to the central control unit is detected.

According to a particular embodiment, the backup analog circuit is configured to transmit the signal representative of the detected rotation speed of the wheel to the local control unit, when a failure of the central control unit to process the wheel rotation speed detection signal is detected.

According to a particular embodiment, the backup circuit comprises an amplifier for amplifying the signal representing the detected rotation speed of the wheel.

According to a particular embodiment, the backup circuit comprises a comparator which is configured to compare the signal representative of the detected rotation speed of the wheel with a threshold value.

According to a particular embodiment, the comparator is a hysteresis comparator with a switch at a first threshold value and at a second threshold value which is strictly greater than the first threshold value.

Preferably the comparator is a Schmitt trigger voltage comparator.

According to a particular embodiment, the backup circuit comprises a filtering device which comprises at least one filter for filtering the detected rotation speed signal of the vehicle wheel.

According to a particular embodiment, the filtering device comprises at least one low-pass filter for filtering noise from the wheel rotation speed detection signal.

Preferably, the low-pass filter is an RC filter that includes a resistor and a capacitor.

According to a particular embodiment, the emergency circuit comprises a switch configured to switch between a first position and a second position. In the first position of the switch, the signal for detecting the rotational speed of the wheel is transmitted to the central control unit by the data transmission network. In the second position of the switch, the signal representative of the detected rotational speed of the wheel is transmitted to the local brake control unit.

The switch is in the second position in particular when a failure of the central control unit has been detected and/or when a failure of the data transmission network has been detected.

The invention also relates to a braking system for a motor vehicle. The braking system comprises at least one brake as defined above, the central control unit, a wheel rotation speed detector, and the data transmission network. The data transmission network is configured to transmit the wheel rotation speed detection signal to the central control unit during normal operation of the braking system.

According to a particular embodiment, the vehicle wheel rotation speed detector comprises a Hall effect sensor.

According to a particular embodiment, the central control unit is a control unit for an electronic trajectory corrector.

According to a particular embodiment, the central control unit is a control unit for an anti-lock braking system.

According to a particular embodiment, the local control unit comprises a computer which is electrically connected to the backup analog circuit.

According to a particular embodiment, the local control unit comprises a computer which is electrically connected to the central control unit by the data transmission network.

According to a particular embodiment, at least one of the central control unit, the local control unit and/or the data transmission network is configured to detect a failure of the data transmission network.

According to a particular embodiment, at least one of the central control unit, the local control unit and/or the data transmission network is configured to detect a failure of the central control unit.

The invention finally relates to a method for controlling the braking of a motorized vehicle wheel by a brake as defined above or by a braking system as defined above.

The braking method comprises transmitting the signal representative of the detected rotational speed of the wheel to the local control unit, after detecting a failure of the braking data transmission network and/or the local control unit. The braking method comprises a braking command of the brake by the local control unit of the brake from the signal representative of the rotational speed of the wheel.

According to a particular embodiment, the braking control method as defined above comprises the transmission of the wheel rotation speed detection signal to the central control unit in normal operation in the absence of detection of a failure of the data transmission network and/or in the absence of detection of a failure of a central braking system control unit. The braking control method comprises a braking control of the brake by the central control unit from the detection of the wheel rotation speed.

The present invention will be better understood upon reading the description of exemplary embodiments, with reference to the appended drawings in which:
There is a schematic representation of a vehicle comprising brakes according to a first embodiment of the invention;
There is a partial schematic representation of a braking system comprising the brakes according to the first embodiment, illustrating the normal operation of a detection of a rotational speed of a wheel which is associated with one of the brakes;
There is a partial schematic representation of a braking system comprising the brakes according to the first embodiment, illustrating the emergency operation of a detection of a rotation speed of a wheel which is associated with one of the brakes;
There is a partial schematic representation of the analog brake backup circuit according to the first embodiment shown;
There is a partial schematic representation of the signal received, partially processed, and processed by the brake backup analog circuit according to the first embodiment shown;
There illustrates a method of controlling braking of a motor vehicle wheel which is intended to be braked by a brake according to the first embodiment.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Identical, similar or equivalent parts of different figures bear the same numerical references so as to facilitate the passage from one figure to another.

There represents a motor vehicle 1 which comprises a braking system 2 and wheels 3, for example four wheels 3 including a left front wheel 3 _FL , a right front wheel 3 _FR , a left rear wheel 3 _RL and a right rear wheel 3 _RR .

Generally, the motorized vehicle 1 comprises at least two wheels 3, preferably at least three wheels and very preferably four wheels. The motorized vehicle 1 is for example a motorcycle. The motorized vehicle is preferably a motor vehicle.

The braking system 2 comprises brakes 4, a brake sensing system 6 and a brake control system 10. The braking system 2 is configured to brake the wheels 3 of the vehicle.

In general, the motor vehicle 1 comprises a braking system 2 according to the invention or at least one brake 4 according to the invention for braking one of the wheels 3 of the motor vehicle 1. The braking system 2 preferably comprises at least two brakes 4 according to the invention, for example the front left brake 4 _FL and right brake 4 _FR , and/or the rear left brake 4 _RL and right brake 4 _RR . Each brake 4 according to the invention is a drive and/or steer wheel brake, or a non-drive and non-steer wheel brake. Preferably, the brake 4 of each drive and/or steer wheel is a brake 4 according to the invention.

With joint reference to FIGS. 1 to 4, the brakes 4 of the vehicle are service brakes, parking brakes and/or emergency brakes. They are each configured to brake one of the wheels 3 of the motor vehicle 1.

Each of the brakes 4 comprises a piston 42, friction elements (not shown) such as drum brake segments or disc brake pads, at least one piston 42, an actuator 40 and a brake control module 16. Each brake 4 is electromechanical and/or hydraulic. Each brake 4 according to the invention is in particular an electromechanical brake and is also optionally hydraulic.

Each of the brakes 4 is for example a disc brake which comprises a disc and a caliper, for example a fixed caliper disc brake or a floating caliper brake. Additionally or alternatively, each of the brakes 4 is a drum brake. The brakes 4 which are on the same axle of the motor vehicle 1, for example the front brakes 4 _FL and 4 _FR or the rear brakes 4 _RL and 4 _RR , are preferably of identical structures.

The piston 42 is a hydraulic and/or electromechanical piston, depending on whether the brake 4 is hydraulic and/or electromechanical. When the brake 4 is a disc brake, the friction elements are pads. When the brake 4 is a drum brake, the friction elements are segments.

The actuator 40 is a hydraulic and/or electromechanical actuator. When the brake 4 is hydraulic, the actuator 40 is a hydraulic actuator and the piston 42 is hydraulic. In this case, the actuator 40 comprises for example a hydraulic chamber which is fluidically connected to a hydraulic circuit (not shown) of the motorized vehicle 1.

When the brake 4 is electromechanical, the actuator 40 is electromechanical and the piston 42 is electromechanical. In this case, the actuator 40 comprises for example a geared motor (not shown) which comprises an electric motor and a reducer. The electric motor is in particular electrically powered by a battery (not shown) of the motorized vehicle.

The actuator 40 is configured to move the piston 42 towards a drum and/or a disc of the brake, the piston 42 pushing at least one of the friction elements towards the drum and/or the disc, to brake the corresponding wheel 3.

The brake control module 16 comprises in particular a local control unit 17, a power supply control member 18 and a connection and data exchange member (not shown). Preferably, the brake control module 16 comprises at least one power supply control member 18 and a connection and data exchange member. The brake control module 16 is configured to control the braking of the wheel on command from a central control unit 12 of the brake control system 10 and/or at least partially independently of the central control unit 12.

The power supply member 18 of the brake is a hydraulic and/or electrical power supply member of the actuator 40.

When the actuator 40 is a hydraulic actuator, the power supply control member 18 is a hydraulic power actuator. The power supply control member 18 controls, for example, a pressurization of the hydraulic circuit of the actuator 40 and of the piston 42 to move the piston 42 and brake the wheel 3. When the actuator 40 is an electromechanical actuator, the power supply control member 18 controls, for example, the electrical power supply of the electric motor of the actuator 40 to move the piston 42 and brake the wheel 3.

The connection and data exchange member is configured to electrically connect and exchange data between the brake control module 16 and the central control unit 12, in particular via the brake data transmission network 80, and preferably only in the direction from the central control unit 12 to the brake control module 16.

The local control unit 17 and the backup analog circuit 5 of a brake control module 16 of a brake 4 according to the invention will be described in detail below with reference to FIGS. 1 to 6.

The braking detection system 6 comprises at least one detector 7 of the rotation speed of a wheel of the motorized vehicle and a network 60 for transmitting detection data and/or supplying power to the detectors. The detection system 6 preferably comprises a detector 7 of the rotation speed per wheel 3 of the vehicle, for measuring the rotation speed of the corresponding wheel 3.

Each rotational speed detector 7 comprises a sensor which is configured to measure the rotational speed of the wheel. The rotational speed detector 7 for example a Hall effect sensor for measuring the rotational speed of the wheel 3, in particular by detecting a variation in magnetic fields linked to the movement of the wheel 3 relative to the Hall effect sensor. With reference to the , the detector 7 delivers a signal for detecting the rotation speed 101 of the corresponding wheel 3.

More generally, the wheel rotation speed detector 7 is notably configured to measure a rotation speed of the wheel 3 by counting a number of times the wheel passes in front of the sensor of the rotation speed detector 7 during a determined duration, preferably a predetermined duration.

The network 60 for transmitting detection data and/or supplying power to the detectors comprises, for example, electrical cables which electrically connect each of the detectors 7 to the central control unit 12 and possibly to the braking control module 16 of the brake 4 of the wheel 3.

The network 60 for transmitting detection data and/or supplying power to the detectors is for example configured to electrically supply each wheel rotation speed detector 7. In addition or as a variant, the network 60 for transmitting detection data and/or supplying power to the detectors is configured to transmit the detection data from each rotation speed detector 7 to the central control unit 12 and/or to the braking control module 16 of each brake 4 according to the invention.

The network 60 for transmitting detection data and/or supplying power to the detectors is preferably configured to operate independently or at least partially independently of a network 8 for transmitting braking data of the braking control system 10, in particular for reasons of redundancy and safety.

With more specific reference to the , the network 60 for transmitting detection data and/or supplying the detectors preferably comprises, for each wheel rotation speed detector 7, at least one input line 61 of the rotation speed detector 7 in normal operation of the braking system 2, and one output line 62 of the rotation speed detector 7 in normal operation of the braking system 2.

With more specific reference to the , the network 60 for transmitting detection data and/or supplying power to the detectors of the braking system 2 according to the invention is distinguished in that it further comprises, for each detector 7 which is connected to a brake 4 according to the invention, an input line 64 of the backup analog circuit in backup operation, a power supply line 66 of the wheel rotation speed detector in backup operation, and an output line 68 for speed detection in backup operation. With reference to the , the network 60 for transmitting detection data and/or supplying power to the detectors also includes in particular an output line 69 of the backup analog circuit in backup operation, which electrically connects the backup analog circuit 5 to the local control unit 17.

The operation of the network 60 for transmitting detection data and/or supplying power to the detectors will be described in detail below with more specific reference to a brake 4 according to the invention, with reference to FIGS. 2 to 6.

The brake control system 10 comprises a central control unit 12, at least one brake control module 16 for each brake 4 according to the invention, and a brake control network 8. The brake control system 10 comprises for example an electronic trajectory corrector and/or an anti-lock wheel device. The brake control system 10 is configured to control the braking and the release of the brakes, in particular the intensity of the braking of each wheel 3 of the motor vehicle 1.

The electronic trajectory corrector is configured to order each of the brakes 4 to brake the corresponding wheel 3 via the control network 8, to electronically correct a trajectory of the motorized vehicle 1. The electronic trajectory corrector controls for example the hydraulic and/or electromechanical braking of each of the brakes 4 independently of the others, to electronically correct a trajectory of the motorized vehicle 1.

The wheel anti-lock device is configured to control the braking of each wheel 3 by the corresponding brake 4, to prevent the locking of each of the wheels 3 of the motor vehicle. The wheel anti-lock device is preferably configured to prevent the slipping of each wheel 3 and at least to prevent the slipping without rolling of each wheel 3 of the motor vehicle 1.

The central control unit 12 comprises a computer such as a microcontroller or a microprocessor. It is configured to at least partially provide the electronic trajectory corrector and/or anti-lock wheel system functions for each of the wheels 3 of the vehicle, in normal operation of the braking system 2. It at least partially provides the electronic trajectory corrector and/or anti-lock wheel system functions for all of the wheels 3 of the vehicle, by providing overall braking control in normal operation of the motorized vehicle 1.

The central control unit 12 is for example configured to command the braking control module 16 of each brake 4 according to the invention to brake the corresponding wheel 3 in normal operation of the braking system 2, in particular by controlling the operation of the power supply member 18 of the control module 16.

As indicated above, each brake control module 16 of a brake 4 according to the invention comprises a local control unit 17. The local control unit 17 comprises a computer such as a microcontroller or a microprocessor, preferably a microcontroller. The local control unit 17 is electrically connected to the backup analog circuit 5 of each brake 4 according to the invention. The local control unit 17 is electrically connected to the central control unit 12 by a braking data transmission network 80 of the braking control network 8.

The local control unit 17 is for example configured to command the power supply member 18 of the braking control module 16 of the brake 4 according to the invention to brake or release the corresponding wheel 3 in normal operation of the braking system 2, in particular on the order of the central control unit 12 in normal operation of the braking system 2.

The local control unit 17 is configured to control the braking of the wheel 10, in particular in the event of failure of the central control unit 12. In this case, it at least partially exercises the functions of electronic trajectory corrector and/or anti-lock system of the corresponding wheel 3 instead of the central control unit 12, by acting on the braking and/or the release of the brakes of the wheel.

The local control unit 17 is for example configured to command the power supply member 18 of the braking control module 16 of the brake 4 according to the invention to brake or release the brakes of the corresponding wheel 3, from a signal representative of the detected rotation speed of the wheel 105 which has been produced by the backup analog circuit 5 of the braking control module 16 in at least one backup operation of the braking system 2 which will be described in detail below.

The brake control network 8 comprises a brake data transmission network 80, for example by data buses, preferably of the CAN type. The brake control network 8 also comprises a hydraulic brake circuit when the brake system 2 comprises at least one hydraulic brake 4.

The brake data transmission network 80 for example electrically connects each of the electromechanical brakes 4 to the central control unit 12, in particular the brake control module 16 of the brake to the central control unit 12, by brake control lines for the left 80 _FL and right 80 _FR front wheels and/or by brake control lines for the left 80 _RL and right 80 _RR rear wheels.

The braking system 2 is now described more specifically in connection with the invention with joint reference to FIGS. 1 to 4 and the operation of the braking system 2 is described with joint reference to FIGS. 1 to 6.

The braking system 2 according to the invention comprises brakes 4 according to the invention and a network 60 for transmitting detection data and/or supplying power to the detectors which is adapted to the brakes 4 according to the invention. Each of the brakes 4 according to the invention is distinguished mainly by its braking control module 16, and in particular in that the braking control module 16 comprises a backup analog circuit 5.

The brake control module 16 of each of the brakes 4 according to the invention comprises a local control unit 17, a power supply control member 18 and a backup analog circuit 5. The power supply control member 18 conforms to what has been generally described previously for the brake control module 16.

With particular reference to the , the backup analog circuit 5 comprises a filtering device 50, 56, an amplifier 52, a signal comparator 54 and a switch 58.

With particular reference to the , the backup analog circuit 5 is configured to transmit the wheel rotation speed detection signal 101, which is delivered by the wheel rotation speed detector 7, directly to the brake data transmission network 80 for routing to the central control unit 12 during normal operation of the brake system 2.

With particular reference to the , the backup analog circuit 5 is configured to transmit a signal representative of a detected rotation speed of the wheel 105 to the local control unit 17 of the brake 4, when a failure of the braking data transmission network 80 is detected and/or when a failure of the central control unit 12 of the braking system 2 of the motor vehicle 1 is detected.

The operation of the braking system 2, in particular of each braking module 16 of a brake 4 according to the invention, in the event of a failure of the braking data transmission network 80 and/or of the central control unit 12 is referred to in this document as emergency operation of the braking system 2, as opposed to the normal operation of the braking system 2 in the absence of detection of at least one of these failures.

The failure of the central control unit 12 is for example a failure of the central control unit 12 to process the rotation speed detection signal 105 of the wheel, in particular to condition this signal.

The failure of the vehicle brake data transmission network 80 is, for example, a failure of the brake data transmission network 80 to transmit a brake command to the brake control module 16 of the brake, following processing of the wheel rotation speed detection signal 101 by the central control unit 12.

The filtering device 50, 56 comprises an input filter 50 which filters a signal at the input of the backup analog circuit 5 and an output filter 56 which filters a signal at the output of the backup analog circuit 5. The input filter 50 and/or the output filter 56 is for example a low-low filter. The input filter 50 and/or the output filter 56 are preferably made up of resistors R1, respectively RF1 and capacitors C1, respectively CF1, each being in particular an “RC” type filter.

More precisely, the input filter 50 is a low-pass filter configured to filter noise from the signal detecting the rotation speed of the wheel 101 which comes directly from the wheel rotation speed detector 7. The output filter 56 is a filter configured to filter noise from the signal representing the detected rotation speed of the wheel 105, in particular created during its passage through operational amplifiers 51, 53 of the backup analog circuit 5.

The amplifier 52 of the backup circuit 5 is configured to amplify the signal at the output of the input filter 50 and before it enters the comparator 54, to facilitate the comparison of the signal in the comparator 54. The amplifier 52 comprises for example an operational amplifier 51, three resistors RG1, RG2 and RG3, and a capacitor CG1. The gain of the amplifier 52 G is for example according to the formula (1) below:

The gain G is for example between 5 and 15, and preferably between 8 and 12, and very preferably approximately equal to 9.5. The gain G of the amplifier 52 is notably chosen from the wheel rotation detector 7 and the comparator 54.

The comparator 54 of the backup circuit 5 is configured to compare the signal at the output of the amplifier 52 to a first threshold value S1 and to a second threshold value S2 which are both non-zero, the second threshold value being strictly greater than the threshold value S1.

In the embodiment shown, the comparator 54 comprises an operational amplifier 53, a first resistor RH1 and a second resistor RH2. The comparator 54 is a Schmitt trigger voltage comparator. More specifically, the comparator 54 is a hysteresis comparator with a trigger at the first threshold value S1 and at the second threshold value S2. The first threshold value S1 is given in particular by the formula (2) below relative to a threshold value at the negative terminal of the operational amplifier 53 and to a supply voltage of the operational amplifier 53:

The first threshold value S1 is for example between 1.5V and 3.5V. It is very preferably equal or substantially equal to 1.8V.

The second threshold value S2 is given in particular by the formula (3) below relative to a threshold value at the negative terminal of the operational amplifier 53:

The second threshold value S2 is for example between 1.5 V and 5 V. It is very preferably equal or substantially equal to 2.5 V.

The switch 58 of the backup analog circuit 5 comprises at least one switch, in particular at least one power switch such as a transistor, preferably a switch circuit. The switch 58 is configured to switch between a first position and a second position.

The switch 58 is in the first position during normal operation of the braking system 2. When the switch 58 is in the first position, the wheel rotation speed detection signal 101 is transmitted to the central control unit 12 by the data transmission network 80.

The switch 58 is in the second position in emergency operation of the braking system 2. When the switch 58 is in the second position, the signal representative of the detected rotational speed of the wheel 105 is transmitted to the local control unit 17 of the brake.

There illustrates the wheel rotation speed detection signal 101 which is delivered by the wheel rotation speed detector 7 and which enters the emergency circuit 5, in normal operation of the braking system 2 and at least in emergency operation of the braking system 2. The wheel rotation speed detection signal 101 is analog, being delivered by a wheel rotation speed detector 7 which comprises an analog sensor.

The detection signal of the rotation speed of the wheel 101 after filtering by the filtering device 50, 56 and amplification by the amplifier 52 is the amplified and filtered signal representative of the rotation speed of the wheel 103, during emergency operation of the braking system 2.

The amplified and filtered signal representative of the rotation speed of the wheel 103 after comparison with the first threshold value S1 and the second threshold value S2 by the Schmitt trigger comparator 54 is the signal representative of the detected rotation speed of the wheel 105 which is delivered at the output of the backup circuit. It takes the form of peaks or plateaus, the peaks or plateaus being representative of the passage of the wheel 3 in front of the Hall effect sensor of the wheel rotation speed detector 7, in particular for a predetermined duration. The signal representative of the detected rotation speed of the wheel 105 is in particular analog and easily digitizable to be transmitted to the local control unit 17, in particular by the output line 69 of the backup analog circuit in backup operation.

The normal operation and the emergency operation of the detection and braking control of the brake 4 according to the invention is now described in detail with joint reference to FIGS. 2 and 3 and to the .

The brake control method 200 starts with detecting the rotational speed of the motor vehicle wheel 201, when the rotational speed detector 7 measures the rotational speed of the wheel and outputs a wheel rotational speed detection signal 101 to the central control unit 12.

The braking control method 200 comprises a detection of a failure 203 of the central control unit 12 and/or of the braking data transmission network 80. The detection of a failure 203 of the braking data transmission network 80 and/or of the central control unit 12, which results in the emergency operation of the braking system 2, is for example carried out by the central control unit 12, by the braking control module 16 of the brake 4 and/or by the data transmission network 80.

In reference to the , the central control unit 12, the brake control module 16 of the brake 4 and/or the brake data transmission network 80 in that they detect a failure of the central control unit 12 and/or the brake data transmission network 80 together form a failure detection system 14 of the central control unit and/or the brake data transmission network. The failure detection system 14 may comprise further failure detectors of the central control unit 12 and/or of the brake data transmission network 80. The failure detection system 14 detects a failure of the central control unit 12 and/or of the brake data transmission network 80 in particular when the wheel rotation speed detection signal 101 is transmitted from the brake control module 16 to the central control unit 12 and the central control unit 12 commands braking or debraking by the brake control module 16 of the brake 4.

In the absence of a failure of the central control unit 12 and/or of the braking data transmission network 80, i.e. in normal operation of the braking system 2, the braking control method 200 continues with the transmission 205 of the signal for detecting the rotational speed of the wheel 101 to the central control unit 12 and the processing of this signal by the central control unit 12.

With more specific reference to the , the switch 58 is in the first position referenced by 1 circled in this figure. The switch 58 is then electrically located between the central control unit 12 and the wheel rotation speed detector 7 which it electrically connects to each other.

The central control unit 12 electrically supplies the wheel speed sensor 7 via the input line 61 of the wheel speed sensor in normal operation of the brake system. The input line 61 of the wheel speed sensor in normal operation of the brake system then serves as an electrical supply line for the wheel speed sensor 7. The wheel speed sensor 7 of the vehicle is electrically connected via the output line 62 of the wheel speed sensor in normal operation to the central control unit 12. The output line 62 of the wheel speed sensor in normal operation carries the detection signal of the wheel speed of the motor vehicle 101.

Referring again to the , the central control unit 12 of the braking system 2 then develops a braking command 207 of the brake 4 from the wheel speed detection signal 101. This braking command 207 is executed by the braking control module 16 of the brake 4 of the wheel 3.

In the event of detection of a failure of the central control unit 12 and/or of the braking data transmission network 80, i.e. in emergency operation of the braking system 2, the braking control method 200 continues with the transmission 209 of the signal representing the rotational speed of the wheel 105 to the braking control module 16 of the brake 4 of the wheel 3. The signal representing the rotational speed of the wheel 105 has been developed by the emergency analog circuit 5 from the wheel rotational speed detection signal 101 which is delivered by the wheel rotational speed detector 7.

With more specific reference to the , the switch 58 is in the second position referenced by 2 circled in this figure. The switch 58 is then electrically located between the wheel rotation speed detector 7 and the local control unit 17 of the brake 4, which it electrically connects to each other.

The fault detection system 14 of the central control unit and/or of the brake data transmission network is electrically connected to the switch 58 by the input line 64 of the backup analog circuit in emergency operation. In particular, it switches the switch 58 from the first position to the second position and/or it is, for example, configured to maintain the switch 58 in the second position until the brake system 2 returns to normal operation.

The wheel rotation speed detector 7 is electrically supplied by a power supply line 66 of the wheel rotation speed detector in emergency operation. This power supply line 66 is different from the input line 61 of the wheel rotation speed detector in normal operation of the braking system.

The vehicle wheel speed sensor 7 is electrically connected to the local control unit 17 of the brake 4 of the wheel 3 by the output line 68 of the emergency wheel speed sensor. The output line 68 of the emergency wheel speed sensor carries the detected speed signal of the motor vehicle wheel 105.

Referring again to the , the local control unit 17 of the brake 4 then generates a braking command 211 of the brake 4 from the signal representing the detected rotation speed of the wheel 105. This braking command 209 is executed by the actuator 40 of the brake 4, in particular via the power supply control member 18.

The locking of each wheel 3 associated with each of the brakes 4 according to the invention tends to be at least limited if not prevented, in the event of failure of the central control unit 12 of the braking system 2 and/or of the braking data transmission network 80 of the motor vehicle 1. In particular, the local control unit 17 of the brake controls for example the brake 4 of the wheel, to prevent the locking of the wheel 3, by ensuring at least partially the function of an anti-lock wheel device in emergency operation.

The speed of the motor vehicle 1 and/or the trajectory of the motor vehicle 1 are capable of being detected, from the signal representative of the detected rotation speed 105 of each of the wheels, in the event of a failure of the central control unit 12 of the braking system 2 and/or of the braking data transmission network 80 of the motor vehicle. In particular, the local control unit 17 of each brake 4 according to the invention detects for example the speed of the motor vehicle 1 and/or the trajectory of the motor vehicle 1, by ensuring at least partially the function of calculator of the detection system 6 in emergency operation.

The control of the speed of the motor vehicle 1 and/or the trajectory of the motor vehicle 1 tends to be improved, for example by controlling the speed of each of the wheels 3 from the signal representative of the detected rotation speed 105 of each of the wheels, in the event of a failure of the central control unit 12 of the braking system 2 and/or of the braking data transmission network 80 of the motor vehicle. In particular, the local control unit 17 of each brake 4 according to the invention controls for example the speed of the motor vehicle 1 and/or the trajectory of the motor vehicle 1, by ensuring at least partially the function of an electronic trajectory corrector of the vehicle in emergency operation.

Of course, various modifications can be made by those skilled in the art to the invention which has just been described without departing from the scope of the disclosure of the invention.

Alternatively, at least one of the brakes 4 does not include a control module 16, for example when the brake 4 is hydraulic and the central control unit 12 hydraulically controls the brake 4 in a fully centralized manner.

Alternatively, at least one of the brakes 4 does not include the power supply member 18, for example when the hydraulic and/or electric power supply of the brake 4 is centralized.

Additionally or alternatively, the data transmission network 80 electrically connects each of the wheel rotation speed sensors 7 to the central control unit 12, for example by brake control lines for the left 80 _FL and right 80 _FR front wheels and/or by brake control lines for the left 80 _RL and right 80 _RR rear wheels. However, the network 60 for transmitting detection data and/or supplying the sensors very preferably connects the wheel rotation speed sensors 7 to the central control unit 12.

Additionally or alternatively, the hydraulic braking circuit comprises at least one brake amplifier which is located between a hydraulic actuating member, for example a brake pedal, and at least one hydraulic brake 4.

Alternatively, the filtering device 50, 56 comprises only one filter. This filter is preferably a low-pass filter and/or it is preferably configured to filter an input signal of the backup analog circuit 5.

NOMENCLATURE IN REFERENCE TO FIGURES

1: motorized vehicle
2: braking system
3: vehicle wheel
3 _FL : left front wheel
3 _FR : right front wheel
3 _RL : left rear wheel
3 _RR : right rear wheel
4: brake
4 _FL : left front brake
4 _FR : right front brake
4 _RL : left rear brake
4 _RR : right rear brake
5: Backup analog circuit
6: Brake detection system
7: wheel rotation speed detector
8: Brake control network
10: Brake control system
12: Central brake control unit
14: central control unit and/or brake data transmission network failure detection system,
16: control module
17: local control unit, brake computer,
18: brake power supply control unit
40: electromechanical and/or hydraulic actuator
42: piston
50: Backup analog circuit input filter
51: operational amplifier
52: Backup analog circuit amplifier
53: comparator operational amplifier
54: wheel speed representative signal comparator
56: Backup circuit output filter
58: Backup analog circuit switch
60: detection data transmission network and/or detector power supply, wheel rotation speed
61: Input line of the wheel rotation speed detector in normal operation
62: Output line of the wheel rotation speed detector in normal operation
64: Backup analog circuit input line, in backup operation
66: Power supply line of the wheel rotation speed detector in emergency operation
68: output line of the wheel rotation speed detector in emergency operation
69: Output lines of the backup analog circuit to the local brake control unit computer
80: Brake data transmission network
80 _FL : Left front wheel brake control line
80 _FR : Right front wheel brake control line
80 _RL : Left rear wheel brake control line
80 _RR : Right rear wheel brake control line
101: Output signal of the rotation speed detector and input of the backup analog circuit
103: amplified and filtered signal representative of the wheel rotation speed
105: output signal of the backup analog circuit representing the detected rotation speed of the wheel
S1: first threshold value of the signal representing wheel speed
S2: second threshold value of the wheel speed representative signal
200: braking control method based on wheel speed detection
201: vehicle wheel rotation speed detection
203: Detection of a failure in the brake data transmission network and/or the central brake control unit
205: transmission of detected wheel speed to the central brake control unit, in normal operation
207: possible braking command from the central control unit
209: transmitting a wheel speed detection signal to the backup analog circuit and processing the detection signal by the backup analog circuit
211: possible braking command from the unit

Claims (15)

Brake (4) for a wheel (3) of a motorized vehicle, comprising:
a local control unit (17) which is configured to control the braking of the wheel (3),
characterized in that the brake (4) comprises a backup analog circuit (5) which is configured to transmit a signal representative of a detected rotational speed of the wheel (105) to the local control unit (17), when a failure of a data transmission network (80) is detected and/or when a failure of a central control unit (12) of the braking system (2) of the motor vehicle (1) is detected. Brake (4) according to the preceding claim, in which the backup analog circuit (5) is configured to transmit the signal representative of the detected rotation speed of the wheel (105) to the local control unit (17), when a failure of the data transmission network (80) for transmitting a signal for detecting the rotation speed of the wheel (101) to the central control unit (12) is detected,
and/or wherein the backup analog circuit (5) is configured to transmit the signal representative of the detected rotational speed of the wheel (105) to the local control unit (17), when a failure of the central control unit (12) to process the detection signal of the rotational speed of the wheel (101) is detected. Brake (4) according to any one of the preceding claims, in which the backup analogue circuit (5) comprises an amplifier (52) for amplifying the signal representative of the detected rotational speed of the wheel (105). Brake (4) according to any one of the preceding claims, in which the backup analog circuit (5) comprises a comparator (54) which is configured to compare the signal representative of the detected rotational speed of the wheel (105) with a threshold value. Brake (4) according to the preceding claim, in which the comparator (54) is a hysteresis comparator with a switch at the first threshold value and at a second threshold value which is strictly greater than the first threshold value,
the comparator (54) preferably being a Schmitt trigger voltage comparator. Brake (4) according to any one of the preceding claims, in which the backup analogue circuit (5) comprises a filtering device (50, 56) which comprises at least one filter for filtering the detected rotational speed signal of the vehicle wheel. Brake (4) according to the preceding claim, in which the filtering device (50, 56) comprises at least one low-pass filter (50, 56) for filtering noise from the signal detecting the rotation speed of the wheel (101),
the low-pass filter (50, 56) preferably being an RC filter which comprises a resistor and a capacitor. Brake (4) according to any one of the preceding claims, in which the backup analog circuit (5) comprises a switch (58) configured to switch between a first position in which the signal for detecting the rotational speed of the wheel (101) is transmitted to the central control unit (12) by the data transmission network (80), and a second position in which the signal representative of the detected rotational speed of the wheel (105) is transmitted to the local control unit (17) of the brake,
the switch (58) being in the second position when a failure of the central control unit (12) has been detected and/or when a failure of the data transmission network (80) has been detected. Braking system (2) for a motor vehicle, comprising at least one brake (4) according to any one of the preceding claims, the central control unit (12), a wheel rotation speed detector (7), and the data transmission network (80),
the data transmission network (80) being configured to transmit the wheel rotation speed detection signal (101) to the central control unit (12) during normal operation of the braking system. Braking system (2) according to the preceding claim, in which the detector of the rotation speed of the wheel (7) of the vehicle comprises a Hall effect sensor. Braking system (2) according to any one of the preceding claims 9 to 10, in which the central control unit (12) is a control unit of an electronic trajectory corrector and/or a control unit of an anti-lock braking system. Braking system (2) according to any one of the preceding claims 9 to 11, in which the local control unit (17) comprises a computer which is electrically connected to the backup analogue circuit (5), and/or
wherein the local control unit (17) comprises a computer which is electrically connected to the central control unit (12) by the data transmission network (80). Braking system (2) according to any one of the preceding claims 9 to 12, wherein the central control unit (12), the local control unit (17) and/or the data transmission network (80) is configured to detect a failure of the data transmission network (80) and/or a failure of the central control unit (12). Method for controlling braking (200) of a wheel (3) of a motorized vehicle by a brake (4) according to any one of the preceding claims 1 to 8 or by a braking system (2) according to any one of claims 9 to 13, comprising:
the transmission (209) of the signal representative of the detected rotation speed of the wheel (105) to the local control unit (17), after detection of a failure (203) of the braking data transmission network (80) and/or of the local control unit (17),
a braking command (211) of the brake (4) by the local control unit (17) of the brake from the signal representative of the rotation speed of the wheel. Braking control method (200) according to the preceding claim comprising:
transmitting (205) the wheel rotation speed detection signal (101) to the central control unit (12) in normal operation in the absence of failure detection (203) of the data transmission network (80) and/or of a central control unit (12) of the braking system,
a braking command (207) of the brake (4) by the central control unit (12) from the detected rotational speed of the wheel.