WO2024090480A1

WO2024090480A1 - Brake system

Info

Publication number: WO2024090480A1
Application number: PCT/JP2023/038524
Authority: WO
Inventors: 賢人橋本; 太宮人河合; 光近藤
Original assignee: 株式会社アドヴィックス
Priority date: 2022-10-27
Filing date: 2023-10-25
Publication date: 2024-05-02
Also published as: JP2024064114A

Abstract

This brake system comprises a plurality of master controllers 50A, 50B, and a plurality of slave controllers 60A to 60D. Power is supplied to the master controller 50A, the slave controller 60B, and the slave controller 60C from a first power supply 11. Power is supplied to the master controller 50B, the slave controller 60A, and the slave controller 60D from a second power supply 12. The master controller 50A and the slave controller 60A are capable of controlling an electric brake 20A. The master controller 50B and the slave controller 60B are capable of controlling an electric brake 20B. The slave controller 60C is capable of controlling an electric brake 20C. The slave controller 60D is capable of controlling an electric brake 20D.

Description

Brake system

The present invention relates to a brake system applied to a vehicle.

Patent Document 1 discloses an example of an in-vehicle system equipped with a vehicle motion integrated control ECU and four BBW driver ECUs. When braking the vehicle, the vehicle motion integrated control ECU calculates command values for the braking forces to be generated on multiple wheels. The vehicle motion integrated control ECU outputs the calculated command values to multiple BBW driver ECUs. The BBW driver ECU controls an electric motor based on the input command values to adjust the braking forces generated on the corresponding wheels.

Patent No. 6214730

When two power sources are provided in a vehicle, the first of the two power sources can supply power to some of the four BBW driver ECUs, and the second power source can supply power to the remaining four BBW driver ECUs. The object of the present invention is to suppress a decrease in the braking force of a vehicle in a brake system capable of supplying power from two power sources when the power supply from one of the two power sources is stopped.

A brake system for solving the above problem is a system applied to a vehicle equipped with a first power source and a second power source different from the first power source. The brake system includes a first electric actuator to a fourth electric actuator that generate a braking force on each of the first to fourth wheels of the vehicle, a driver that adjusts the power supplied from the first electric actuator to one of the fourth electric actuators, a braking force calculation unit that calculates the braking force generated on the first to fourth wheels by driving the first to fourth electric actuators, and a plurality of master controllers including a driver control unit that operates the driver according to the calculation result of the braking force calculation unit, and a plurality of slave controllers including a driver that adjusts the power supplied from the first electric actuator to one of the fourth electric actuators, and a driver control unit that operates the driver according to the calculation result of the braking force calculation unit of the master controller. A first master controller of the plurality of master controllers and a first slave controller and a second slave controller of the plurality of slave controllers constitute a first controller group that is not supplied with power from the second power source but is supplied with power from the first power source. A second master controller of the plurality of master controllers and a third slave controller and a fourth slave controller of the plurality of slave controllers constitute a second controller group to which power is not supplied from the first power source but is supplied from the second power source. A first prescribed controller of the first controller group and a second prescribed controller of the second controller group both control the first electric actuator. A third prescribed controller of the first controller group different from the first prescribed controller and a fourth prescribed controller of the second controller group different from the second prescribed controller both control the second electric actuator. One controller of the first controller group different from the first prescribed controller and the third prescribed controller controls the third electric actuator. One controller of the second controller group different from the second prescribed controller and the fourth prescribed controller controls the fourth electric actuator.

In the above brake system, even if the power supply from the first power source is stopped, if power is supplied from the second power source, the multiple controllers constituting the second controller group can operate with power supplied from the second power source. Therefore, braking force can be generated on three of the four wheels. Conversely, even if the power supply from the second power source is stopped, if power is supplied from the first power source, the multiple controllers constituting the first controller group can operate with power supplied from the first power source. Therefore, braking force can be generated on three of the four wheels.

Therefore, the above brake system can suppress a decrease in braking force when power supply from either the first power source or the second power source is stopped.

FIG. 1 is a schematic diagram showing a vehicle to which a brake system according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing the configuration of the brake system. FIG. 3 is a table showing the relationship between the master controller that calculates the command braking force to be adopted and the driver who operates the brake control device of the brake system when the brake control device can be operated normally. FIG. 4 is a table showing the relationship between the master controller that calculates the command braking force to be adopted and the driver who operates when the power supply from one of the first power source and the second power source is stopped. FIG. 5 is a table showing the relationship between the master controller that calculates the command braking force to be adopted and the driver who will act when one of the two master controllers fails. FIG. 6 is a flowchart showing a series of processes executed by the master controller. FIG. 7 is a flowchart showing a series of processes executed by the slave controller. FIG. 8 is a block diagram showing the configuration of a brake system according to a modified example.

Hereinafter, an embodiment of a brake system will be described with reference to FIGS.
<General configuration of the vehicle>
1 illustrates a vehicle 10 to which a brake system is applied. The vehicle 10 has a front left wheel FL, a front right wheel FR, a rear left wheel RL, and a rear right wheel RR as wheels. The vehicle 10 has a first power source 11 and a second power source 12 separate from the first power source 11 as a source of power supply to the brake system.

<Electric brakes for brake system>
1 and 2, the brake system 100 includes four electric brakes. The four electric brakes correspond to the four wheels FL, FR, RL, and RR, respectively. That is, the four electric brakes include an electric brake 20A that generates a braking force on the left front wheel FL, an electric brake 20B that generates a braking force on the right front wheel FR, an electric brake 20C that generates a braking force on the left rear wheel RL, and an electric brake 20D that generates a braking force on the right rear wheel RR. Hereinafter, the

electric brakes

20A and 20B for the front wheels may be referred to as "front wheel

electric brakes

20A and 20B," and the

electric brakes

20C and 20D for the rear wheels may be referred to as "rear wheel

electric brakes

20C and 20D."

The front wheel

electric brakes

20A, 20B each include a rotating body 21, a friction member 22, an electric motor 23, a reduction mechanism 24, and a linear motion conversion mechanism 25. The rotating body 21 rotates integrally with the front wheels FL, FR. In the front wheel

electric brakes

20A, 20B, the rotational motion of the electric motor 23 is reduced by the reduction mechanism 24 and output to the linear motion conversion mechanism 25. The rotational motion input to the linear motion conversion mechanism 25 is then converted to linear motion by the linear motion conversion mechanism 25 and output to the friction member 22. In other words, the front wheel

electric brakes

20A, 20B adjust the braking force generated on the front wheels FL, FR by controlling the electric motor 23. The electric motor 23 is a double-winding motor.

The multiple rear wheel

electric brakes

20C, 20D each include a rotating body 31, a friction member 32, an electric motor 33, a reduction mechanism 34, and a linear motion conversion mechanism 35. The rotating body 31 rotates integrally with the rear wheels RL, RR. In the

electric brakes

20C, 20D, the rotational motion of the electric motor 33 is reduced by the reduction mechanism 34 and output to the linear motion conversion mechanism 35. The rotational motion input to the linear motion conversion mechanism 35 is then converted to linear motion by the linear motion conversion mechanism 35 and output to the friction member 32. In other words, the rear wheel

electric brakes

20C, 20D adjust the braking force generated on the rear wheels RL, RR by controlling the electric motor 33. Note that unlike the electric motor 23, the electric motor 33 is not a double-winding motor.

In this embodiment, the

electric motors

23, 33 of the electric brakes 20A to 20D correspond to the "electric actuators." In particular, the electric motor 23 of the electric brake 20A for the left front wheel corresponds to the "first electric actuator," and the electric motor 23 of the electric brake 20B for the right front wheel corresponds to the "second electric actuator." The electric motor 33 of the electric brake 20C for the left rear wheel corresponds to the "third electric actuator," and the electric motor 33 of the electric brake 20D for the right rear wheel corresponds to the "fourth electric actuator." The left front wheel FL, which generates a braking force by driving the first electric actuator, is also referred to as the "first wheel." The right front wheel FR, which generates a braking force by driving the second electric actuator, is also referred to as the "second wheel." The left rear wheel RL, which generates a braking force by driving the third electric actuator, is also referred to as the "third wheel." The right rear wheel RR, which generates a braking force by driving the fourth electric actuator, is also referred to as the "fourth wheel."

<Brake control device for brake system>
The brake system 100 includes a brake control device 40 that controls four electric brakes 20A to 20D. The brake control device 40 includes a left front wheel control unit 41A, a right front wheel control unit 41B, a left rear wheel control unit 41C, and a right rear wheel control unit 41D. The left front wheel control unit 41A controls the electric brake 20A for the left front wheel. The right front wheel control unit 41B controls the electric brake 20B for the right front wheel. The left rear wheel control unit 41C controls the electric brake 20C for the left rear wheel. The right rear wheel control unit 41D controls the electric brake 20D for the right rear wheel. The multiple control units 41A to 41D are each configured to be able to transmit and receive information via a brake control device internal communication 42. For example, the brake control device internal communication 42 is a CAN bus. "CAN" is an abbreviation for "Controller Area Network".

The left front wheel control unit 41A has a master controller 50A and a slave controller 60A. The master controller 50A and the slave controller 60A are each configured to be able to send and receive information to and from each other within the left front wheel control unit 41A.

The right front wheel control unit 41B has a master controller 50B and a slave controller 60B. The master controller 50B and the slave controller 60B are each configured to be able to send and receive information to and from each other within the right front wheel control unit 41B.

The left rear wheel control unit 41C has a slave controller 60C but does not have a master controller. The right rear wheel control unit 41D has a slave controller 60D but does not have a master controller.

The

multiple controllers

50A, 50B, 60A to 60D constituting the brake system 100 can be classified into a first controller group to which power is supplied from the first power source 11, and a second controller group to which power is supplied from the second power source 12. The first controller group includes the master controller 50A of the

multiple master controllers

50A, 50B, and also includes the slave controller 60B and slave controller 60C of the multiple slave controllers 60A to 60D. On the other hand, the second controller group includes the master controller 50B of the

multiple master controllers

50A, 50B, and also includes the slave controller 60A and slave controller 60D of the multiple slave controllers 60A to 60D. Note that power is not supplied from the second power source 12 to the

multiple controllers

50A, 60B, 60C constituting the first controller group. Power is not supplied from the first power source 11 to the

multiple controllers

50B, 60A, 60D constituting the second controller group.

In this embodiment, the master controller 50A corresponds to the "first master controller" and the master controller 50B corresponds to the "second master controller." Furthermore, the slave controller 60B constituting the first controller group corresponds to the "first slave controller," and the slave controller 60C constituting the first controller group corresponds to the "second slave controller." Furthermore, the slave controller 60A constituting the second controller group corresponds to the "third slave controller," and the slave controller 60D constituting the second controller group corresponds to the "fourth slave controller."

The master controller 50A of the first controller group and the slave controller 60A of the second controller group both control the first electric actuator. In this embodiment, the electric motor 23 of the left front wheel control unit 41A corresponds to the first electric actuator, so the master controller 50A corresponds to the "first prescribed controller" and the slave controller 60A corresponds to the "second prescribed controller". As described above, the electric motor 23 is a double-winding motor. Therefore, the master controller 50A adjusts the current flowing through the first winding of the two windings of the electric motor 23, and the slave controller 60A adjusts the current flowing through the second winding of the two windings of the electric motor 23. Therefore, when at least one of the master controller 50A and the slave controller 60A is operating, the braking force generated on the left front wheel FL can be adjusted by driving the electric motor 23.

The master controller 50B of the second controller group and the slave controller 60B of the first controller group both control the second electric actuator. In this embodiment, since the electric motor 23 of the right front wheel control unit 41B corresponds to the second electric actuator, the master controller 50B corresponds to the "fourth prescribed controller" and the slave controller 60B corresponds to the "third prescribed controller". As described above, the electric motor 23 is a double-winding motor. Therefore, the master controller 50B adjusts the current flowing through the first winding of the two windings of the electric motor 23, and the slave controller 60B adjusts the current flowing through the second winding of the two windings of the electric motor 23. Therefore, when at least one of the master controller 50B and the slave controller 60B is operating, the braking force generated on the right front wheel FR can be adjusted by driving the electric motor 33.

Of the first controller group, the slave controller 60C, which is different from the master controller 50A and the slave controller 60B, controls the third electric actuator. In this embodiment, the electric motor 33 of the left rear wheel control unit 41C corresponds to the third electric actuator, so the slave controller 60C can adjust the braking force generated on the left rear wheel RL by driving the electric motor 33 of the left rear wheel control unit 41C.

Of the second controller group, a slave controller 60D, which is different from the master controller 50B and the slave controller 60A, controls the fourth electric actuator. In this embodiment, the electric motor 33 of the right rear wheel control unit 41D corresponds to the fourth electric actuator, so the slave controller 60D can adjust the braking force generated on the right rear wheel RR by driving the electric motor 33 of the right rear wheel control unit 41D.

The

multiple master controllers

50A, 50B each have a first driver 51 and a master microcomputer 52. The master microcomputer 52 includes an execution unit and a memory unit that stores a control program executed by the execution unit. For example, the execution unit is a CPU. Since the electric motor 23 is a double-winding motor, the first driver 51 is electrically connected to only the first winding of the two windings of the electric motor 23. The execution unit of the master microcomputer 52 operates the first driver 51 by executing the control program. As a result, the execution unit can drive the electric motor 23 by adjusting the current flowing through the first winding of the electric motor 23.

Each of the slave controllers 60A to 60D has a second driver 61 and a slave microcomputer 62. The slave microcomputer 62 includes an execution unit and a memory unit that stores a control program executed by the execution unit. For example, the execution unit is a CPU. Since the electric motor 23 is a double-winding motor, the second driver 61 is electrically connected only to the second winding of the two windings of the electric motor 23. The execution unit of the slave microcomputer 62 in the

slave controllers

60A and 60B operates the second driver 61 by executing the control program. As a result, the execution unit can drive the electric motor 23 by adjusting the current flowing through the second winding of the electric motor 23.

The execution unit of the slave microcomputer 62 in the

slave controllers

60C and 60D executes the control program to operate the second driver 61. This allows the execution unit to drive the electric motor 33 by adjusting the current flowing through the windings of the electric motor 33.

Here, the multiple master microcomputers 52 communicate with devices installed in the vehicle in addition to the brake system 100 via the in-vehicle network 43. On the other hand, the multiple slave microcomputers 62 are not connected to the in-vehicle network 43. For example, the in-vehicle network 43 is a CAN bus. By connecting the master microcomputer 52 to the in-vehicle network 43 while not connecting the slave microcomputer 62 to the in-vehicle network 43, there is no need to make the slave microcomputer 62 a security-enabled microcomputer. As a result, it is possible to configure the brake system 100 at low cost. Note that the slave microcomputer 62 transmits and receives information only within the brake system 100 using the brake control device internal communication 42.

Incidentally, in the brake system 100, the left front wheel control unit 41A and the electric brake 20A are unitized to form a brake unit for the left front wheel. The right front wheel control unit 41B and the electric brake 20B are unitized to form a brake unit for the right front wheel. The left rear wheel control unit 41C and the electric brake 20C are unitized to form a brake unit for the left rear wheel. The right rear wheel control unit 41D and the electric brake 20D are unitized to form a brake unit for the right rear wheel.

<Controller functional configuration>
The functional configuration of the controller will be described with reference to FIG.
The execution units of the

master controllers

50A, 50B execute a control program to function as a braking force calculation unit M11 and a driver control unit M13. The braking force calculation unit M11 and the driver control unit M13 are functional units for driving the electric motor.

The braking force calculation unit M11 calculates the braking force to be generated at the wheels by driving the electric motor of the electric brake. For example, the braking force calculation unit M11 calculates the command braking force, which is the command value of the braking force to be generated at the wheels, for each of the wheels FL, FR, RL, and RR based on the required deceleration value of the vehicle 10. That is, the braking force calculation unit M11 calculates the command braking force FbA for the left front wheel FL, the command braking force FbB for the right front wheel FR, the command braking force FbC for the left rear wheel RL, and the command braking force FbD for the right rear wheel RR.

The driver control unit M13 adjusts the power supplied to the electric motor 23 of the front wheel electric brake by operating the first driver 51 according to the calculation result of the braking force calculation unit M11. Specifically, the driver control unit M13 of the left front wheel control unit 41A adjusts the power supplied to the electric motor 23 of the left front wheel electric brake 20A by operating the first driver 51 based on the command braking force FbA for the left front wheel FL. The driver control unit M13 of the right front wheel control unit 41B adjusts the power supplied to the electric motor 23 of the right front wheel electric brake 20B by operating the first driver 51 based on the command braking force FbB for the right front wheel FR.

The execution units of the multiple slave controllers 60A-60D each function as a driver control unit M23 by executing a control program. The driver control unit M23 is a functional unit for driving the electric motor. Note that the execution units of the slave controllers 60A-60D do not function as braking force calculation units.

The driver control unit M23 of the

slave controllers

60A, 60B for the front wheels adjusts the power supplied to the electric motor 23 of the front wheel electric brake by operating the second driver 61 according to the calculation result of the braking force calculation unit M11. Specifically, the driver control unit M23 of the left front wheel control unit 41A adjusts the power supplied to the electric motor 23 of the left front wheel electric brake 20A by operating the second driver 61 based on the command braking force FbA for the left front wheel FL. The driver control unit M23 of the right front wheel control unit 41B adjusts the power supplied to the electric motor 23 of the right front wheel electric brake 20B by operating the second driver 61 based on the command braking force FbB for the right front wheel FR.

The driver control unit M23 of the

slave controllers

60C, 60D for the rear wheels adjusts the power supplied to the electric motor 33 of the rear wheel electric brake by operating the second driver 61 according to the calculation result of the braking force calculation unit M11. Specifically, the driver control unit M23 of the left rear wheel control unit 41C adjusts the power supplied to the electric motor 33 of the left rear wheel electric brake 20C by operating the second driver 61 based on the command braking force FbC for the left rear wheel RL. The driver control unit M23 of the right rear wheel control unit 41D adjusts the power supplied to the electric motor 33 of the right rear wheel electric brake 20D by operating the second driver 61 based on the command braking force FbD for the right rear wheel RR.

<Braking control during normal operation>
Brake control in normal operation will be described with reference to Fig. 3. "Normal" here refers to a state of the brake control device 40 in which power is supplied to the brake system 100 from both the first power source 11 and the second power source 12, and all of the

master controllers

50A, 50B are operating normally. In Figs. 3 to 5, "MC1" indicates the master controller 50A, and "MC2" indicates the master controller 50B. Also, "SC1" indicates the slave controller 60A, "SC2" indicates the slave controller 60B, "SC3" indicates the slave controller 60C, and "SC4" indicates the slave controller 60D.

The left front wheel control unit 41A operates based on the command braking force FbA calculated by the braking force calculation unit M11 of the master controller 50A. That is, the driver control unit M13 of the master controller 50A operates the first driver 51 based on the command braking force FbA calculated by the braking force calculation unit M11 of the master controller 50A. Also, the driver control unit M23 of the slave controller 60A operates the second driver 61 based on the command braking force FbA calculated by the braking force calculation unit M11 of the master controller 50A.

In the following description, the command braking force calculated by the braking force calculation unit M11 of the master controller 50A is referred to as the "command braking force calculated by the master controller 50A." Also, the command braking force calculated by the braking force calculation unit M11 of the master controller 50B is referred to as the "command braking force calculated by the master controller 50B."

The right front wheel control unit 41B operates based on the command braking force FbB calculated by the master controller 50B. That is, the driver control unit M13 of the master controller 50B operates the first driver 51 based on the command braking force FbB calculated by the master controller 50B. Also, the driver control unit M23 of the slave controller 60B operates the second driver 61 based on the command braking force FbB calculated by the master controller 50B.

The left rear wheel control unit 41C operates based on the command braking force FbC calculated by the master controller 50B. That is, the driver control unit M23 of the slave controller 60C operates the second driver 61 based on the command braking force FbC calculated by the master controller 50B.

The right rear wheel control unit 41D operates based on the command braking force FbD calculated by the master controller 50A. That is, the driver control unit M23 of the slave controller 60D operates the second driver 61 based on the command braking force FbD calculated by the master controller 50A.

<Braking control when power supply from the power source to the brake system is stopped>
Referring to FIG. 4, braking control will be described in a case where power is supplied to the brake system 100 from one of the first power source 11 and the second power source 12, but power supply to the brake system 100 from the other power source is stopped.

First, a case where power supply from the first power source 11 to the brake system 100 is stopped will be described. In this case, the

controllers

50A, 60B, and 60C that make up the first controller group do not operate.

The left front wheel control unit 41A operates based on the command braking force FbA calculated by the master controller 50B. That is, the driver control unit M23 of the slave controller 60A operates the second driver 61 based on the command braking force FbA calculated by the master controller 50B.

The right front wheel control unit 41B operates based on the command braking force FbB calculated by the master controller 50B. That is, the driver control unit M13 of the master controller 50B operates the first driver 51 based on the command braking force FbB calculated by the master controller 50B.

When power supply to the slave controller 60C is stopped, the second driver 61 of the slave controller 60C does not operate. As a result, the left rear wheel control unit 41C does not operate, and the slave controller 60C cannot adjust the braking force generated on the left rear wheel RL.

The right rear wheel control unit 41D operates based on the command braking force FbD calculated by the master controller 50B. That is, the driver control unit M23 of the slave controller 60D operates the second driver 61 based on the command braking force FbD calculated by the master controller 50B.

On the other hand, a case where power supply from the second power source 12 to the brake system 100 is stopped will be described. In this case, the

controllers

50B, 60A, and 60D constituting the second controller group do not operate.

The left front wheel control unit 41A operates based on the command braking force FbA calculated by the master controller 50A. That is, the driver control unit M13 of the master controller 50A operates the first driver 51 based on the command braking force FbA calculated by the master controller 50A.

The right front wheel control unit 41B operates based on the command braking force FbB calculated by the master controller 50A. That is, the driver control unit M23 of the slave controller 60B operates the second driver 61 based on the command braking force FbB calculated by the master controller 50A.

The left rear wheel control unit 41C operates based on the command braking force FbC calculated by the master controller 50A. That is, the driver control unit M23 of the slave controller 60C operates the second driver 61 based on the command braking force FbC calculated by the master controller 50A.

When power supply to the slave controller 60D is stopped, the second driver 61 of the slave controller 60D does not operate. As a result, the right rear wheel control unit 41D does not operate, and the slave controller 60D cannot adjust the braking force generated on the right rear wheel RR.

<Braking control when the master controller fails>
5, a braking control in a case where one of the

multiple master controllers

50A, 50B operates normally while the other fails will be described. Here, the description will be given on the assumption that power is supplied to the brake system 100 from both the first power source 11 and the second power source 12.

First, a case where the master controller 50A fails will be described.
The left front wheel control unit 41A operates based on the command braking force FbA calculated by the master controller 50B. That is, the slave controller 60A operates the second driver 61 based on the command braking force FbA calculated by the master controller 50B. At this time, since the master controller 50A has failed, the first driver 51 of the left front wheel control unit 41A cannot operate.

Next, a case where the master controller 50B fails will be described.
The left front wheel control unit 41A operates based on the command braking force FbA calculated by the master controller 50A. That is, the driver control unit M13 of the master controller 50A operates the first driver 51 based on the command braking force FbA calculated by the master controller 50A. Also, the driver control unit M23 of the slave controller 60A operates the second driver 61 based on the command braking force FbA calculated by the master controller 50A.

The right front wheel control unit 41B operates based on the command braking force FbB calculated by the master controller 50A. That is, the slave controller 60B operates the second driver 61 based on the command braking force FbB calculated by the master controller 50A. At this time, because the master controller 50B has failed, the first driver 51 of the right front wheel control unit 41B cannot operate.

<Processing flow executed by the master microcomputer of the master controller>
A master side process, which is a series of processes executed by the master microcomputer 52 of the

master controllers

50A and 50B, will be described with reference to Fig. 6. The master microcomputer 52 repeatedly executes the master side process at each predetermined control cycle.

In step S11, the master microcomputer 52 functions as a braking force calculation unit M11 to calculate command braking forces FbA to FbD for the multiple wheels FL, FR, RL, and RR. That is, the master microcomputer 52 of the master controller 50A and the master microcomputer 52 of the master controller 50B each calculate the command braking forces FbA to FbD for the multiple wheels FL, FR, RL, and RR.

In step S13, the master microcomputer 52 transmits the command braking force calculated in step S11. Specifically, the master microcomputer 52 of the master controller 50A transmits the command braking forces FbB, FbC, and FbD for the wheels FR, RL, and RR other than the left front wheel FL to the brake control device internal communication 42. The master microcomputer 52 of the master controller 50A also transmits the command braking force FbA for the left front wheel FL to the slave controller 60A. Meanwhile, the master microcomputer 52 of the master controller 50B transmits the command braking forces FbA, FbC, and FbD for the wheels FL, RL, and RR other than the right front wheel FR to the brake control device internal communication 42. The master microcomputer 52 of the master controller 50B also transmits the command braking force FbB for the right front wheel FR to the slave controller 60B.

In step S15, the master microcomputer 52 functions as the driver control unit M13 to operate the first driver 51 based on the command braking force. Specifically, the master microcomputer 52 of the master controller 50A operates the first driver 51 of the electric brake 20A based on the command braking force FbA for the left front wheel FL that it has calculated. Meanwhile, the master microcomputer 52 of the master controller 50B operates the first driver 51 of the electric brake 20B based on the command braking force FbB for the right front wheel FR that it has calculated. After that, the master microcomputer 52 temporarily ends the master-side processing.

<Processing flow executed by the slave microcomputer of the slave controller>
Slave-side processing, which is a series of processing executed by the slave microcomputer 62 of each of the slave controllers 60A to 60D, will be described with reference to Fig. 7. The slave microcomputer 62 repeatedly executes the slave-side processing for each predetermined control cycle.

In step S21, the slave microcomputer 62 obtains a command braking force for operating the second driver 61.
Specifically, when the slave microcomputer 62 of the slave controller 60A of the left front wheel control unit 41A receives the command braking force FbA from the master controller 50A, it acquires the command braking force FbA calculated by the master controller 50A. When the slave microcomputer 62 of the slave controller 60A cannot receive the command braking force FbA from the master controller 50A but can receive the command braking force FbA calculated by the master controller 50B from the brake control device internal communication 42, it acquires the command braking force FbA calculated by the master controller 50B.

When the slave microcomputer 62 of the slave controller 60B of the right front wheel control unit 41B receives the command braking force FbB from the master controller 50B, it acquires the command braking force FbB calculated by the master controller 50B. If the slave microcomputer 62 of the slave controller 60B cannot receive the command braking force FbB from the master controller 50B but can receive the command braking force FbB calculated by the master controller 50A from the brake control device internal communication 42, it acquires the command braking force FbB calculated by the master controller 50A.

The slave microcomputer 62 of the slave controller 60C of the left rear wheel control unit 41C acquires the command braking force FbC calculated by the master controller 50B if the command braking force FbC calculated by the master controller 50B can be acquired from the braking control device internal communication 42. Even if the slave microcomputer 62 of the slave controller 60C cannot receive the command braking force FbC calculated by the master controller 50B, if the slave microcomputer 62 of the slave controller 60C can receive the command braking force FbC calculated by the master controller 50A from the braking control device internal communication 42, the slave microcomputer 62 acquires the command braking force FbC calculated by the master controller 50A.

The slave microcomputer 62 of the slave controller 60D of the right rear wheel control unit 41D acquires the command braking force FbD calculated by the master controller 50A if the command braking force FbD calculated by the master controller 50A can be acquired from the braking control device internal communication 42. Even if the slave microcomputer 62 of the slave controller 60D cannot receive the command braking force FbD calculated by the master controller 50A, if the slave microcomputer 62 of the slave controller 60D can receive the command braking force FbD calculated by the master controller 50B from the braking control device internal communication 42, the slave microcomputer 62 acquires the command braking force FbD calculated by the master controller 50B.

In step S23, the slave microcomputer 62 operates the second driver 61 based on the command braking force acquired in step S21. Specifically, the slave microcomputer 62 of the slave controller 60A of the left front wheel control unit 41A operates the second driver 61 of the electric brake 20A based on the command braking force FbA. The slave microcomputer 62 of the slave controller 60B of the right front wheel control unit 41B operates the second driver 61 of the electric brake 20B based on the command braking force FbB. The slave microcomputer 62 of the slave controller 60C of the left rear wheel control unit 41C operates the second driver 61 of the electric brake 20C based on the command braking force FbC. The slave microcomputer 62 of the slave controller 60D of the right rear wheel control unit 41D operates the second driver 61 of the electric brake 20D based on the command braking force FbD. After that, the slave microcomputer 62 temporarily ends the slave side processing.

<Actions and Effects of the Present Embodiment>
(1) Even if the power supply from the first power source 11 to the brake system 100 is stopped, if the power is supplied from the second power source 12 to the brake system 100, the controllers of the second controller group operate. Therefore, braking force can be generated on three of the four wheels FL, FR, RL, and RR. On the other hand, even if the power supply from the second power source 12 to the brake system 100 is stopped, if the power is supplied from the first power source 11 to the brake system 100, the controllers of the first controller group operate. Therefore, braking force can be generated on three of the four wheels FL, FR, RL, and RR. Therefore, the brake system 100 can suppress a decrease in the braking force of the vehicle 10 when the power supply from one of the first power source 11 and the second power source 12 is stopped.

Note that, if the controllers in the first controller group are operable but the controllers in the second controller group are inoperable, braking force can be generated on the wheels FL, FR, RL other than the right rear wheel RR. On the other hand, if the controllers in the second controller group are operable but the controllers in the first controller group are inoperable, braking force can be generated on the wheels FL, FR, RR other than the left rear wheel RL.

In addition, the first controller group is supplied with power from the first power source 11, but not from the second power source 12. The second controller group is supplied with power from the first power source 11, but not from the first power source 11. This prevents a situation in which a controller in the first controller group or a controller in the second controller group has a ground fault, causing the potentials of the first power source 11 and the second power source 12 to drop simultaneously, resulting in an inability to supply power to the brake system 100.

(2) Consider a case where the electric motor 23 of the front wheel control unit has only one winding. In this case, in order to enable either the master controller or the slave controller of the front wheel control unit to operate the driver of the electric motor 23, a switching circuit may be provided in the front wheel control unit to switch the controller that controls the driver between the master controller and the slave controller. When switching the controller that controls the driver from one of the master controller and the slave controller to the other, it becomes necessary to operate the switching circuit, and there is a risk that control of the electric motor 23 may be temporarily interrupted during the switchover.

In this regard, in the brake system 100, the electric motor 23 of the front wheel control unit is a double-winding motor. Of the two windings, the first winding is electrically connected to the first driver 51 of the master controller, and the second winding is electrically connected to the second driver 61 of the slave controller. When both the master controller and the slave controller are operating, both the first driver 51 and the second driver 61 operate. Therefore, even if the operation of one of the master controller and the slave controller stops while the electric motor 23 is being driven, it is possible to continue control of the electric motor 23. In other words, it is possible to prevent the control of the electric motor 23 from being temporarily interrupted.

(3) The electric motor 23 of the front wheel control unit is a double-winding motor, and the front wheel control unit includes both a master controller and a slave controller. Furthermore, one of the master controller and the slave controller constitutes a first controller group, and the other constitutes a second controller group. Therefore, even if the power supply from one of the first power source 11 and the second power source 12 to the brake system 100 is stopped, braking force can be generated at the multiple front wheels FL, FR.

(4) The

multiple master controllers

50A, 50B calculate the command braking forces FbA to FbD for the multiple wheels FL, FR, RL, and RR, respectively. Therefore, even if only one of the

multiple master controllers

50A, 50B fails, the multiple control units 41A to 41D can obtain the command braking forces, and the multiple control units 41A to 41D can drive the electric motors, respectively. Therefore, even if only one of the

multiple master controllers

50A, 50B fails, braking forces can be generated for the multiple wheels FL, FR, RL, and RR.

(5) Unlike the

master controllers

50A and 50B, the slave controllers 60A to 60D do not have the function of calculating the command braking forces FbA to FbD. Therefore, a microcomputer with lower functionality than the master microcomputer 52 of the

master controllers

50A and 50B can be used as the slave microcomputer 62 of the slave controllers 60A to 60D. In other words, the brake system 100 can suppress a decrease in the braking force of the vehicle 10 when the power supply from one of the two

power sources

11 and 12 is stopped, while suppressing an increase in cost. Here, a "low-performance microcomputer" includes a microcomputer with a lower operating frequency and a smaller number of CPU cores compared to a microcomputer that is not low-performance.

(6) In this embodiment, the electric brake 20A for the front wheels and the master controller 50A are integrated into a unit, so the driver control unit M13 and the first driver 51 are located near the electric motor 23. The effects of this arrangement are described below. The driver control unit M13 needs to give precise instructions to the driver who operates the electric motor 23, so it needs to perform calculations at a control cycle that is faster than the communication within the brake control device 42. Therefore, if the signal of the driver control unit M13 is transmitted and received via the communication within the brake control device 42, the control accuracy of the electric motor 23 may decrease. On the other hand, the braking force calculation unit M11 does not need to perform calculations at a calculation cycle that is faster than the communication within the brake control device 42, so the control accuracy of the electric motor 23 does not decrease even if the signal of the braking force calculation unit M11 is transmitted and received via the communication within the brake control device 42.

As described above, by unitizing the master controller 50A including the braking force calculation unit M11, driver control unit M13, and first driver 51 with the electric brake 20A, the signal of the driver control unit M13 of the master controller 50A can be transmitted to the first driver 51 without being sent or received via the braking control device internal communication 42. And because the master controller 50A and the electric brake 20A are unitized, the first driver 51 can directly supply power to the electric motor 23 of the electric brake 20A. Therefore, by making use of the driver control unit M13 of the master controller 50A and transmitting the signal of the braking force calculation unit M11 to other control units via the braking control device internal communication 42, a redundant configuration can be achieved without increasing the number of microcomputers, and an inexpensive brake system can be configured. On the other hand, if the master controller is not united with the electric brake, the driver control unit of the master controller cannot be utilized. In other words, as described above, the communication 42 in the brake control device cannot transmit signals at a cycle faster than the calculation cycle of the driver control unit M13. Therefore, if the front wheels are configured redundantly as in this embodiment, it is necessary to add a slave microcomputer to each of the control units of the front wheels that are united with the electric brake, and the number of microcomputers in the brake system increases by two. It is possible to utilize the driver control unit of the master controller even if the master controller is not united with the electric brake, but in that case, the physical distance between the driver and the electric motor will be increased. In other words, since signals from the driver control unit M13 to the driver cannot be transmitted and received by the communication 42 in the brake control device, when the driver control unit M13 is utilized, the driver control unit M13 and the driver must be physically located in close proximity. This results in a longer path between the driver and the electric motor through which a large current flows, which has the disadvantages of increasing the cost of the wire harness and decreasing the driving efficiency of the electric motor due to increased wiring resistance, and the configuration of this embodiment is advantageous.

In addition, in this embodiment, the left front wheel control unit 41A and the right front wheel control unit 41B have the same configuration, and the left rear wheel control unit 41C and the right rear wheel control unit 41D have the same configuration, so the units can be standardized, resulting in a cheaper brake system.

<Example of change>
The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

- An electric motor with one winding is used as the electric motor equipped in the front wheel

electric brakes

20A, 20B, and the front

wheel control units

41A, 41B are configured to have only the slave controller out of the master controller and slave controller. In this case, a double-winding motor is used as the electric motor equipped in the rear wheel

electric brakes

20C, 20D, and the rear

wheel control units

41C, 41D are configured to have both a master controller and a slave controller.

In this modified example, the left rear wheel RL corresponds to the first wheel, the right rear wheel RR corresponds to the second wheel, the left front wheel FL corresponds to the third wheel, and the right front wheel FR corresponds to the fourth wheel. Also, the electric motor of the electric brake 20C for the left rear wheel corresponds to the first electric actuator, the electric motor of the electric brake 20D for the right rear wheel corresponds to the second electric actuator, the electric motor of the electric brake 20A for the left front wheel corresponds to the third electric actuator, and the electric motor of the electric brake 20B for the right front wheel corresponds to the fourth electric actuator. The master controller of the left rear wheel control unit, the slave controller of the right rear wheel control unit, and the slave controller of the left front wheel control unit constitute a first controller group. The master controller of the right rear wheel control unit, the slave controller of the left rear wheel control unit, and the slave controller of the right front wheel control unit constitute a second controller group. In this case, the master controller of the left rear wheel control unit corresponds to the first prescribed controller, and the slave controller of the left rear wheel control unit corresponds to the second prescribed controller. Additionally, the slave controller of the right rear wheel control unit corresponds to the third prescribed controller, and the master controller of the right rear wheel control unit corresponds to the fourth prescribed controller.

Even with this configuration, braking force can be generated on the three wheels even if the power supply to the brake system from one of the first power source 11 and the second power source 12 is stopped. Furthermore, even if the power supply from the first power source 11 is stopped, or the power supply from the second power source 12 is stopped, braking force can be generated on the two rear wheels RL and RR.

- The electric motor controlled by the control unit having both a master controller and a slave controller does not have to be a double-winding motor. In this case, it is preferable to provide the control unit with a switching circuit for switching the controller that controls the driver between the master controller and the slave controller. With this configuration, if the operation of one of the master controller and the slave controller stops, the electric motor can be driven by operating the driver using the other controller through the operation of the switching circuit.

A brake system 1000 shown in FIG. 8 may be used as the brake system.
The brake control device 400 of the brake system 1000 will be described with reference to Fig. 8. The brake control device 400 includes a left front wheel control unit 41A1, a right front wheel control unit 41B1, a left rear wheel control unit 41C, and a right rear wheel control unit 41D. The left front wheel control unit 41A1 includes a master controller 50A1 and a master controller 50A2. Each of the master controllers 50A1 and 50A2 includes a first driver 51 and a master microcomputer 52. Of the two windings of the electric motor 23 of the electric brake 20A for the left front wheel, the first winding is electrically connected to the first driver 51 of the master controller 50A1, and the second winding is electrically connected to the first driver 51 of the master controller 50A2.

The right front wheel control unit 41B1 has a slave controller 60B1 and a slave controller 60B2. These two slave controllers 60B1, 60B2 each have a second driver 61 and a slave microcomputer 62. Of the two windings of the electric motor 23 of the electric brake 20B for the right front wheel, the first winding is electrically connected to the second driver 61 of the slave controller 60B1, and the second winding is electrically connected to the second driver 61 of the slave controller 60B2.

In the braking control device 400, the master controller 50A1 and the slave controller 60B1 are classified into a first controller group, and the master controller 50A2 and the slave controller 60B2 are classified into a second controller group. In this case, the master controller 50A1 of the first controller group corresponds to the "first prescribed controller", and the master controller 50A2 of the second controller group corresponds to the "second prescribed controller". In addition, the slave controller 60B1 of the first controller group corresponds to the "third prescribed controller", and the slave controller 60B2 of the second controller group corresponds to the "fourth prescribed controller". Therefore, in the brake system 1000, braking force can be generated at the three wheels even if the power supply from the first power source 11 is stopped or even if the power supply from the second power source 12 is stopped.

Furthermore, as further configurations different from that of FIG. 8, a left rear wheel control unit having a master controller, a right rear wheel control unit having a master controller, a left front wheel control unit having a first slave controller and a second slave controller, and a right front wheel control unit having a first slave controller and a second slave controller may be used. In brake system 1000 of this configuration, braking force can be generated at three wheels even when power supply from first power source 11 is stopped or when power supply from second power source 12 is stopped. In this configuration, since the master controller is located at the rear of the vehicle, it is possible to reduce the occurrence of an event in which both master controllers fail due to an impact at the front of the vehicle, and it is also possible to standardize the units.

Similarly, two master controllers may be placed in the front wheel control unit and one in the rear wheel control unit. In this arrangement, it is possible to reduce the likelihood of both master controllers failing due to an impact to the front or rear of the vehicle.

- The master controller 50A may calculate the command braking force FbB for the right front wheel FR and the command braking force FbC for the left rear wheel RL only when the master controller 50B is unable to calculate the command braking force. Scenario where the master controller 50B is unable to calculate the command braking force includes when the power supply to the master controller 50B is stopped and when an abnormality such as a breakdown occurs in the master controller 50B.

Similarly, the master controller 50B may calculate the command braking force FbA for the left front wheel FL and the command braking force FbD for the right rear wheel RR only when the master controller 50A is unable to calculate the command braking force. Scenario where the master controller 50A is unable to calculate the command braking force includes when the power supply to the master controller 50A is stopped and when an abnormality such as a breakdown occurs in the master controller 50A.

- When the brake system 100 is normal, both the left rear wheel control unit 41C and the right rear wheel control unit 41D may operate the second driver 61 based on the command braking force calculated by the master controller 50A. Also, both the left rear wheel control unit 41C and the right rear wheel control unit 41D may operate the second driver 61 based on the command braking force calculated by the master controller 50B.

- The electric actuator may be an actuator other than an electric motor, so long as the electric actuator is driven to cause the electric brake to generate a braking force on the wheels.

- The electric brakes do not have to be dry electric brakes as shown in FIG. 1, as long as they are brakes that can generate a braking force on the wheels according to the drive amount of the electric actuator. For example, the electric brakes may be wet electric brakes equipped with an electric cylinder powered by an electric motor. Also, for example, among the multiple electric brakes, some of the electric brakes may be dry electric brakes, and the remaining electric brakes may be wet electric brakes.

- In the above embodiment, the vehicle has four wheels, but the number of wheels is not limited to four. For example, if the number of wheels is six, a brake unit can be provided for the additional two wheels, combining a control unit with the same configuration as the rear wheel control unit and an electric brake with the same configuration as the rear wheel electric brake. In this case, it is preferable to supply power from different power sources to the brake units for the additional two wheels. With this configuration, braking force for four of the six wheels can be guaranteed even if one of the power sources fails.

- A microcomputer may be configured as a circuit including one or more processors that operate according to a computer program, one or more dedicated hardware circuits such as dedicated hardware that executes at least some of the various processes, or a combination of these. An example of dedicated hardware is an ASIC, which is an application specific integrated circuit. The processor includes a CPU and memory such as RAM and ROM, and the memory stores program code or instructions configured to cause the CPU to execute processes. Memory, i.e., storage media, includes any available media that can be accessed by a general-purpose or dedicated computer.

The expression "at least one" used in this specification means "one or more" of the desired options. As an example, the expression "at least one" used in this specification means "only one option" or "both of two options" if the number of options is two. As another example, the expression "at least one" used in this specification means "only one option" or "any combination of two or more options" if the number of options is three or more.

<Other technical ideas>
The technical ideas that can be understood from the above-described embodiment and modified examples will be described as supplementary notes.
[Supplementary Note 1] It is preferable that the first electric actuator and the second electric actuator are driven so as to generate braking forces on left and right front wheels of the vehicle, respectively.

[Additional Note 2] The first electric actuator is an actuator that is driven to generate a braking force on the first wheel,
the second electric actuator is an actuator that is driven to generate a braking force on the second wheel,
the third electric actuator is an actuator that is driven to generate a braking force on the third wheel,
the fourth electric actuator is an actuator that is driven to generate a braking force on the fourth wheel,
the first defining controller is the first master controller;
The third defining controller is preferably the second master controller.

[Additional Note 3] The braking force calculation unit of the first master controller
calculating a braking force to be generated on the first wheel by driving the first electric actuator;
It is preferable that a braking force to be generated on the fourth wheel by driving the fourth electric actuator is calculated.

[Additional Note 4] The braking force calculation unit of the second master controller
calculating a braking force to be generated on the second wheel by driving the second electric actuator;
It is preferable that a braking force to be generated on the third wheel by driving the third electric actuator is calculated.

[Supplementary Note 5] The second defining controller is the third slave controller,
The fourth defining controller is preferably the first slave controller.

Claims

A brake system applied to a vehicle having a first power source and a second power source separate from the first power source,
a first electric actuator to a fourth electric actuator for generating a braking force on each of a first wheel to a fourth wheel of the vehicle;
a plurality of master controllers including a driver that adjusts the power supplied to any one of the first electric actuator to the fourth electric actuator, a braking force calculation unit that calculates a braking force to be generated from the first wheel to the fourth wheel by driving the first electric actuator to the fourth electric actuator, and a driver control unit that operates the driver in accordance with a calculation result of the braking force calculation unit;
a driver that adjusts the power supplied to any one of the first electric actuator to the fourth electric actuator, and a plurality of slave controllers including a driver control unit that operates the driver in accordance with a calculation result of the braking force calculation unit of the master controller,
a first master controller among the plurality of master controllers, and a first slave controller and a second slave controller among the plurality of slave controllers, constitute a first controller group to which power is supplied from the first power source while not supplied from the second power source;
a second master controller among the plurality of master controllers, and a third slave controller and a fourth slave controller among the plurality of slave controllers constitute a second controller group to which power is not supplied from the first power source but is supplied from the second power source;
a first defining controller of the first controller group and a second defining controller of the second controller group both control the first electric actuator;
a third definition controller of the first controller group different from the first definition controller, and a fourth definition controller of the second controller group different from the second definition controller, both of which control the second electric actuator;
one controller of the first controller group, which is different from the first defining controller and the third defining controller, controls the third electric actuator;
A brake system in which one controller of the second controller group, which is different from the second definition controller and the fourth definition controller, controls the fourth electric actuator.
the first electric actuator is a double-winding motor having a winding electrically connected to the driver of the first specified controller and a winding electrically connected to the driver of the second specified controller,
2. The brake system according to claim 1, wherein the second electric actuator is a double-winding motor having a winding electrically connected to the driver of the third specification controller and a winding electrically connected to the driver of the fourth specification controller, separately provided.
3. The brake system according to claim 1, wherein at least one of the first master controller and the second master controller is unitized with any one of the first electric actuator to the fourth electric actuator.