Patent Publication Number: US-2022234558-A1

Title: Electric brake system for vehicles

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of international patent application PCT/EP2020/080634, filed Nov. 2, 2020 designating the United States and claiming priority from German application 10 2019 130 233.1, filed Nov. 8, 2019, and the entire content of both applications is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to an electric brake system for vehicles and a method for controlling a brake system for vehicles. 
     BACKGROUND 
     Brake systems for vehicles are well known. DE 10 2004 009 469 A1 describes an electronically controlled electromechanical brake control system for a utility vehicle. The vehicle has a front axle having two wheels, a rear axle having two wheels and a service brake for braking the wheels. A brake unit for brake actuation is associated with each of the four wheels. The brake units are electrically controllable. A first central control device is further provided for controlling the brake units. A second central control device is furthermore provided as a redundant control device with respect to the first control device. An axle modulator is associated with each axle, which axle modulator determines a wheel brake command for each wheel on the axle associated therewith from an axle brake command from the central control unit. A dynamic adaptation of the brake commands takes place in the central control units for the purpose of vehicle stabilization. 
     A brake system with reduced complexity is desired for the improvement of vehicle brake systems. 
     SUMMARY 
     It is an object of the present disclosure to provide an electric brake system for vehicles with reduced complexity. An object of the present disclosure is, in particular, to provide an electric brake system for vehicles with reduced costs. 
     This object can, for example, be achieved by an electric vehicle brake system for a vehicle which has a brake value encoder, at least one first axle having at least two wheels and a second axle having at least two wheels. A first axle modulator is associated with the first axle. A second axle modulator is associated with the second axle. A single central control unit is further provided, which generates and outputs a first brake signal for the first axle modulator and a second brake signal for the second axle modulator as a function of a brake signal from the brake value encoder or as a function of the brake signal from a further brake request (for example, from driver assist systems) which is communicated to the central control unit via a data connection. The first and second axle modulator are each configured to decelerate the wheels of the first and second axle as a function of the first and second brake signal from the central control unit. 
     An electric vehicle brake system or a brake system for vehicles having only a single central control unit (central module) is therefore provided. An axle modulator is associated with each axle of the vehicle, which axle modulator receives a brake signal from the central control unit in each case and initiates a corresponding deceleration at the wheels of the respective axle. The axle modulator has at least one brake modulator for each of the wheels connected to the axle. The brake modulator acts on the brake actuator so that the wheels are braked. 
     The central control unit receives a brake signal from a brake value encoder or from an eligible system of the vehicle. The central control unit converts the received brake signal into brake signals for the first and second axle modulator in order to enable deceleration or braking of the vehicle. The axle modulator receives the respective brake signal from the central control unit and converts the brake signal into a signal for the brake actuators via the brake modulators. 
     According to an embodiment, each axle modulator has an axle control unit and at least two brake modulators. The brake modulators each generate brake modulator signals for controlling the brake actuators and output these signals to the brake actuators, which are provided directly on the respective wheel. 
     According to an embodiment, the axle modulators receive the brake signal from the brake value encoder as an input signal in addition to the first or second brake signal from the central control unit. The axle modulators use the brake signal from the brake value encoder as an input signal for generating the brake modulator signals if a fault occurs in or at the central control unit. 
     Accordingly, the brake signal from the brake value encoder is output not only to the central control unit but also to each of the axle modulators. As a result of the axle modulators receiving the brake signal from the brake value encoder, the axle modulators can also enable redundant braking in the event of a failure of the central control unit or in the event of a fault in the line between the central control unit and the respective axle modulators. The safety of the brake system can therefore also be ensured with a reduction in the complexity of the brake system and an associated reduction in costs. 
     According to a further embodiment, at least one axle modulator signal line is provided between at least two axle modulators. This serves for the communication between the axle modulators, in particular if there is a fault in or at the central control unit. Equalization of the axle brake forces, which can improve the vehicle stability and the brake power, can therefore also take place in the event of a failure of the central control unit. 
     The disclosure likewise relates to a vehicle, in particular a utility vehicle, having a brake value encoder, at least one first axle having at least two wheels, a second axle having at least two wheels and at least one electric brake system described above. 
     According to an embodiment, the mass of the vehicle is distributed substantially evenly to the first and second axle. Alternatively, the mass of the vehicle can also be distributed unevenly to the axles. 
     The disclosure likewise relates to a method for controlling an electric brake system for vehicles, which has a brake value encoder, at least one first axle having at least two wheels and a second axle having at least two wheels. A first axle modulator is associated with the first axle and at least one second axle modulator is associated with the second axle. A first brake signal is generated for the first axle modulator and a second brake signal is generated for the second axle modulator by a single central control unit as a function of a brake signal from the brake value encoder,. The wheels of the first and second axle are braked as a function of the first and second brake signal from the central control unit. 
     While, in the prior art, two central and redundant central control units in the form of central modules of the brake system are provided. the brake system of the disclosure manages with only one single central control unit. The central control unit functions as a central module of the brake system and serves to control and monitor the electrically regulated brake system. A setpoint deceleration of the vehicle is determined from a signal of the brake value encoder. By way of example, the setpoint deceleration together with the respective wheel speeds of the wheels of the vehicle can be used as an input signal for an electronic regulating system. In the case of an electronically regulated pneumatic brake system, this regulating system determines pressure setpoint values for the brake system at the front axle and at the rear axle. For the electric brake system, the regulating system determines electrical setpoint values for controlling the electric brake actuators. The setpoint values are compared with actual values and differences can be corrected. The central control unit is connected to the axle modules and exchanges data and in particular the respective brake signal for the respective axle modulators. 
     According to an aspect of the present disclosure, an axle modulator is provided for each axle. The axle modulator represents an axle control unit. The axle modulator can optionally have pneumatic pressure regulating channels. 
     The axle modulator can have an additional connection for a redundant pneumatic brake circuit. 
     The axle modulator can have a control unit or a control module, which enable ABS (anti-lock brake system) control of the wheels which are connected to the axle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the drawings wherein: 
         FIG. 1  shows a schematic illustration of a brake system according to a first embodiment; and, 
         FIG. 2  shows a schematic illustration of a brake system according to a second embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a schematic illustration of a brake system according to a first embodiment. A vehicle  200  (in particular a utility vehicle) has a brake system  100 . The vehicle  200  has a brake value encoder  210  and at least two axles  220 ,  230 , each having at least two wheels  221 ,  222 ,  231 ,  232 . The wheels  221 ,  222 ,  231 ,  232  can represent driven or non-driven wheels. The brake system  100  according to the first embodiment is configured as an electronically regulated brake system (EBS) for vehicles, in particular utility vehicles. These utility vehicles or vehicles can preferably have a similar mass distribution M 1 , M 2  to the front axle and rear axle. The mass M of the vehicles is therefore substantially not unevenly distributed. Such utility vehicles  200  can be buses or trucks with a loading surface or box body. 
     According to an aspect of the disclosure, the central control unit can, however, also take into account an uneven axle load distribution. However, a failure of the central control unit then means that a dynamic axle-load-dependent brake force distribution can no longer be ensured. It is, however, possible to cope with the failure of the dynamic axle-load-dependent brake force distribution  470  in vehicles with a typically equal axle load distribution. For other vehicles with an uneven load distribution, an axle modulator signal line  115  may he necessary, via which the axle modulators are able to ensure a brake force distribution. 
     The brake system  100  has a (single) central control unit  110 . The central control unit  110  corresponds, for example, to a central module in an electronic brake system EBS. The brake system  100  has a first and second axle modulator  120 ,  130 . An axle modulator  120 ,  130 ,  140  can preferably be provided for each axle  220 ,  230 ,  240  of the vehicle  200 . The central control unit  110  receives a brake signal  211  from the brake value encoder  210  of the vehicle  200 . The brake signal  211  is optionally likewise supplied directly to the at least one first and second axle modulator  120 ,  130 . 
     In an embodiment, the brake signal from the brake value encoder is provided via a plurality of signal lines, wherein each signal line is connected to a respective axle modulator. All signal lines together are moreover likewise connected to the central control unit. 
     The axle modulators  120 ,  130  each have an axle control unit  121 .  131  and brake modulators  122 ,  132  for each wheel which is arranged on the axle. 
     The first axle modulator  120  receives a first brake signal  111  from the central control unit  110  via the line  110   a  and the second axle modulator  130  receives a second brake signal  112  from the central control unit  110  via the line  110   b.    
     A brake actuator  123   a,    123   b,    133   a,    133   b  is provided in or at each wheel  221 ,  222 ,  231 ,  232  of the vehicle, which brake actuator is controlled by the respective brake modulators  122 ,  132 . 
     For the electronically regulated brake system EBS, a deceleration is determined by the central control unit  110  as a function of the brake signal  211  from the brake value encoder  210  and as a function of vehicle stability programs and/or driver assist systems. The vehicle stability programs and/or driver assist systems can be realized in the central control unit  110  or connected to the central control unit  110 , The central control unit  110  then generates a brake signal  111 ,  112  for each of the axle modulators  120 ,  130 . The axle modulators  120 ,  130  convert this brake information into signals for the respective brake actuators  123   a,    123   b,    133   a,    133   b  via the brake modulators  122 ,  132 . 
     The axle modulators  120 ,  130  optionally receive not only the first and second brake signal  111 ,  112  from the central control unit  110 , but also the brake signal  211  directly from the brake value encoder  210 . This takes place in order to provide a safety redundancy, in particular for the event that the central control unit or the signal lines  110   a,    110   b  are disrupted. Should this occur, based on the brake signal  211  received directly from the brake value encoder  120 ,  130 , the axle modulators  120 ,  130  can then control the respective brake actuators  123   a,    123   b,    133   a,    133   b  accordingly via the brake modulators  122 ,  132  in order to enable braking of the vehicle. 
     The brake actuators can be driven or actuated hydraulically, pneumatically or electrically. 
     If, in the event of a fault, the central control unit  110  and/or the signal lines  110   a,    110   b  are defective, the axle modulators initiate deceleration of the vehicle based on the brake signal  211  an optionally taking into account brake force distribution parameters. 
     In the event of a fault (defect of the central control unit  110  or the signal line  110   a,    110   b ), the axle modulators can also effect a deceleration of the vehicle without the central control unit  110 . However, this then also means that it is not possible to also take into account the vehicle stability program  410  and/or driver assist systems  420  which are realized or taken into account by the central control unit  110 . 
     Each axle modulator  120 ,  130  is associated with an axle  220 ,  230  of the vehicle  200 . The axle modulators  120 ,  130  can preferably be provided in, on or in the vicinity of the respective axle  220 ,  230 . Each axle modulator  120 ,  130  has an axle control unit  121 ,  131 , two brake modulators  122 ,  132  and electromechanical brake actuators  123   a,    123   b,    133   a,    133   b.  The brake modulators have optionally electric or electronic switch units for controlling and transmitting power to the electromechanical brake actuators. 
     According to an aspect of the present disclosure, a third signal line  115  is optionally provided between the first and second axle modulator  120 ,  130 . In the event of a fault  430  (failure of the central control unit  110 ), the axle modulators  120 ,  130  could therefore communicate with one another in order to be able to realize a desired deceleration of the vehicle. In this case, it is not only possible to also take into account the brake force distribution parameters, but for a brake force distribution  470  to also take place depending on the situation, with the aim being the best possible vehicle deceleration with the best possible vehicle stability. This is beneficial in particular in vehicles with an uneven weight distribution M 1 , M 2 . In the event of such a fault  430 , vehicle assist systems  410  and vehicle stability systems  420  cannot also be taken into account since these are only processed or taken into account by the central control unit  110 . 
     The brake modulators  122 ,  132  output a brake modulation signal  122   a,    132   a  to the brake actuators  123   a,    123   b,    133   a,    133   b,  which causes the brake actuators  123 ,  133  to implement a desired deceleration or a desired braking. 
     According to an aspect of the present disclosure, the brake actuators  123   a,    123   b,    133   a,    133   b  can be controlled electrically. This is advantageous since there is no need for further or additional intelligence to be present in the brake actuators and in the brake modulator. This is in particular advantageous with regard to the reliability of the brake modulators and the brake actuators. In particular, these are less susceptible to shocks and weather influences and temperature influences. 
     According to an aspect of the present disclosure, the respective axle modulators  120 ,  130  optionally comprise all of the electronics required for determining the respective brake signals and controlling the brake actuators. Since the axle modulators  120 ,  130  are provided in, on or in the vicinity of the axle  220 ,  230 , they are less exposed to the weather influences than electronics which are integrated in or on the wheel. 
     The brake system  100  further has an energy supply unit  150 . This energy supply can be connected to an energy supply of the vehicle and has a previously specified storage option to enable the brake system to still be supplied with energy in the event of a fault. In particular, the energy supply unit  150  can have multiple rechargeable accumulators  151 . 
     The axle modulators  120 ,  130  and in particular the axle control unit  121 ,  131  are optionally suitable for implementing ABS (anti-lock brake system) regulation independently of the central control unit  110 . 
     The brake system  100  can optionally have a redundant brake unit  300  (for example, a pneumatic brake circuit), which operates independently of the central control unit  100  and enables at least emergency braking in the event of a fault in or at the central control unit  110 . To this end, the brake unit  300  can be coupled to the axle modulators  120 ,  130 ,  140  via lines  301 ,  302 ,  303 . The axle modulators can therefore have an additional connection for a redundant pneumatic brake circuit. Alternatively, the brake unit  300  can also be coupled directly to the brake modulators or the brake actuators. 
       FIG. 2  shows a schematic illustration of a brake system according to a second embodiment. The brake system according to the second embodiment corresponds substantially to the brake system according to the first embodiment, wherein the vehicle has three axles  220 ,  230 ,  240 . The brake system according to the second embodiment therefore has three axle modulators  120 ,  130 ,  140 , The configuration of the respective axle modulators according to the second embodiment corresponds to the configuration of the axle modulators according to the first embodiment. Each axle modulator therefore receives a brake signal  111 ,  112 ,  113  from the central control unit  110  and a brake signal  211  from the brake value encoder  210 . The signal line  115  can optionally extend between adjacent axle modulators  120 ,  130 ,  140 , so that the axle modulators can communicate with one another via the third signal line  115 , in particular in the event of a fault. 
     It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims. 
     LIST OF REFERENCE SIGNS AS PART OF THE DESCRIPTION 
       100  Brake system 
       110  Central control unit 
       111  First brake signal 
       112  Second brake signal 
       110   a  First signal line 
       110   b  Second signal line 
       110   c  Third signal line 
       115  Axle modulator signal line 
       120  First axle modulator 
       121  Axle control unit 
       121  Brake modulator 
       122   a  Brake modulator signal 
       123   a, b  Brake actuator 
       130  Second axle modulator 
       131  Axle control unit 
       132  Brake modulator 
       132   a  Brake modulator signal 
       133   a, b  Brake actuator 
       140  Third axle modulator 
       141  Axle control unit 
       142  Brake modulation 
       142   a  Brake modulator signal 
       143   a, b  Brake actuator 
       150  Energy supply unit 
       151  Rechargeable accumulator 
       200  Vehicle 
       210  Brake value encoder 
       211  Brake signal 
       220  First axle 
       221  Wheel 
       222  Wheel 
       230  Second axle 
       231  Wheel 
       232  Wheel 
       240  Third axle 
       241  Wheel 
       242  Wheel 
       300  Brake unit 
       400  Further brake request 
       410  Vehicle stability program 
       420  Driver assist program 
       430  Fault 
       440  Brake force distribution 
       450  Emergency brake request 
       460  Brake force distribution parameter 
       470  Brake force distribution 
     M Mass 
     M 1 , M 2  Mass distribution 
     ABS Anti-lock brake system