JP7772001B2 - Vehicle brake system - Google Patents

Description

This specification discloses a vehicle brake device.

Brake-by-wire is a well-known vehicle braking system. In a brake-by-wire system, the driver's operation of the brake pedal is converted into an electrical signal. This electrical signal is then processed to control the brakes.

In such brake-by-wire systems, there are known examples in which the brake system is divided into an upstream brake mechanism and a downstream brake mechanism. For example, the upstream brake mechanism generates hydraulic pressure based on the amount of brake pedal operation. In the downstream brake mechanism, the hydraulic pressure generated by the upstream brake mechanism is distributed as brake pressure to each of the four wheels.

The upstream and downstream brake mechanisms are powered by the vehicle's main power supply. A power failure occurs when the power supply does not supply power properly or at all due to a hardware or software failure. To prepare for a main power failure, the vehicle is equipped with a backup power supply.

For example, in Patent Document 1, in addition to the main power supply, a vehicle is provided with a first backup power supply device and a second backup power supply. If the main power supply fails, power is supplied from the first backup power supply to a first actuator in the upstream brake mechanism. Furthermore, in this case, if the first backup power supply is not sufficiently charged, power is supplied to the first actuator from the second backup power supply.

In conventional brake systems, as in Patent Document 1, the backup power supply is connected exclusively to the upstream brake mechanism to ensure power to that mechanism. Meanwhile, the backup power supply is not connected to the downstream brake mechanism. For example, in the event of a main power failure, the valve of the downstream brake mechanism is opened, and hydraulic pressure based on brake pedal operation is applied directly as braking pressure to the wheels. By limiting the backup power supply's power supply to the upstream brake mechanism, power to the upstream brake mechanism is ensured.

Japanese Patent Application Laid-Open No. 2021-90246

The upstream and downstream brake mechanisms each have an actuator that generates hydraulic pressure. When inspecting the operation of these actuators, power is supplied to each actuator. As mentioned above, in conventional brake systems, power from the backup power supply is supplied exclusively to the upstream brake mechanism. This makes it difficult to inspect the operation of the downstream brake mechanism using the backup power supply.

This specification discloses a vehicle brake system. This system enables operational inspection of the upstream brake mechanism and downstream brake mechanism using a backup power supply. Furthermore, when the main power supply fails while the vehicle is running, this system ensures that power is supplied from the backup power supply to the upstream brake mechanism.

This specification discloses a vehicle brake device. The device includes an upstream brake mechanism, a downstream brake mechanism, an upstream power line, a downstream power line, and a power supply controller. The upstream brake mechanism generates hydraulic pressure based on the amount of brake pedal operation. The downstream brake mechanism distributes the hydraulic pressure generated by the upstream brake mechanism to brake pressure for each wheel. The upstream power line connects the upstream brake mechanism to a backup power source. The downstream power line includes a backup power cable and a backup switch. The backup power cable connects the backup power source to the downstream brake mechanism. The backup switch is provided on the backup power cable. The power supply controller includes a switch operation unit. The switch operation unit is capable of operating the backup switch. The switch operation unit performs a switching determination. The switching determination determines whether to switch the backup switch from an off state to an on state. This switching determination is performed when the vehicle comes to a stop and the cruise control system is turned off.

With the above configuration, power can be supplied from the backup power supply to the downstream brake mechanism via the downstream power line. Furthermore, the switching decision is made after driving has ended. In other words, the power supply from the backup power supply to the downstream brake mechanism is suppressed while the vehicle is driving. This ensures that power can be supplied from the backup power supply to the upstream brake mechanism while the vehicle is driving.

In the above configuration, the power supply controller may also include a management unit. The management unit calculates the SOC of the backup power supply. In this case, the switch operation unit determines whether the backup power supply is fully charged as a switching determination.

The above configuration makes it possible to prevent the backup power supply from running out of power while inspecting the operation of the upstream and downstream brake mechanisms.

In the above configuration, the vehicle brake device may also include a main power line and a downstream brake controller. The main power line includes a main power cable and a main switch. The main power cable connects the main power source and the downstream brake mechanism. The main switch is provided on the main power cable. The downstream brake controller is capable of operating the main switch. The voltage of the main power source may exceed the voltage of the backup power source. In this case, the downstream brake controller switches the main switch from an on state to an off state when the backup switch is switched from an off state to an on state.

The above configuration prevents power from being supplied from the main power supply rather than from the backup power supply when the backup power supply is connected to the downstream brake.

In the above configuration, the backup power supply may be a capacitor cell. In this case, when the vehicle is stopped and the driving control system is turned off, the power supply controller discharges the capacitor cell until the charge level reaches zero.

With the above configuration, the power from the capacitor cells, which was previously wasted, can be used to check the operation of the upstream and downstream brake mechanisms.

The vehicle brake device disclosed in this specification makes it possible to inspect the operation of the upstream brake mechanism and downstream brake mechanism using a backup power supply. At the same time, if the main power supply fails while the vehicle is running, power supply from the backup power supply to the upstream brake mechanism is ensured.

1 is a brake system diagram illustrating a vehicle brake device according to an embodiment of the present invention; 1 is a diagram illustrating an example of an outline of power supply and signal transmission/reception of a vehicle brake device according to an embodiment of the present invention. 10 is a flowchart illustrating a self-check process.

The vehicle brake device according to this embodiment will be described below with reference to the drawings. The shapes, materials, quantities, and values described below are examples for illustrative purposes only and can be changed as appropriate depending on the specifications of the vehicle brake device. Furthermore, the same reference numerals will be used to designate equivalent elements in all drawings below.

<Overall structure>
Fig. 1 illustrates a brake system diagram of a vehicle brake device according to this embodiment, and Fig. 2 illustrates an outline of power supply and signal transmission/reception of the vehicle brake device according to this embodiment.

A vehicle brake system can apply brake pressure to the vehicle's four wheels (front right wheel, front left wheel, rear right wheel, and rear left wheel). Vehicle brake systems are hydraulic, and pressure is transmitted via brake fluid.

The vehicle brake system is a so-called brake-by-wire type brake system. The vehicle brake system is divided into three systems: an upstream brake system, a downstream brake system, and a power supply system.

The upstream brake system includes an upstream brake mechanism 10 and an upstream brake controller 100. In the upstream brake system, hydraulic pressure corresponding to the amount of operation of the brake pedal 14 is generated by driving the motor M1.

The downstream brake system includes a downstream brake mechanism 50 and a downstream brake controller 110. In the downstream brake system, the hydraulic pressure generated in the upstream brake system is distributed to brake parts Bfr, Bfl, Brr, and Brl provided on each of the vehicle's four wheels.

The upstream brake system and downstream brake system each include multiple actuators. These actuators include solenoid valves, motors, and cut valves. Details of these devices are described below.

Power is supplied to these actuators from a power supply system. As illustrated in FIG. 2, the power supply system includes a main power supply 60, a backup power supply 70, and a power supply controller 80. As described below, when the driving control system is turned off after vehicle operation has ended, a self-check is performed on the upstream brake system and downstream brake system. The self-check is an operational check of the actuators of the upstream brake system and downstream brake system.

This self-check uses power from the main power supply 60 or the backup power supply 70. In particular, when the backup power supply 70 is fully charged, the power required for the self-check is supplied exclusively from the backup power supply 70.

<Upstream braking system>
Referring to FIG. 1, the upstream brake system includes an upstream brake mechanism 10 and an upstream brake controller 100 .

The upstream brake mechanism 10 generates hydraulic pressure according to the amount of operation of the brake pedal 14. The upstream brake mechanism 10 includes a reservoir 12, a brake pedal 14, a master cylinder 20, a stroke simulator SS, and multiple actuators. As actuators, the upstream brake mechanism 10 includes a motor M1, a pump P1, solenoid valves SLM1 and SLM2, and cut valves SGH and SSA. Furthermore, the upstream brake mechanism 10 includes hydraulic sensors Sgap and Ssrv.

The reservoir 12 stores brake fluid, which serves as a pressure transmission medium. The master cylinder 20 generates hydraulic pressure primarily for the front wheels according to the amount of operation of the brake pedal 14. The master cylinder 20 includes an operating rod 18, an input piston 21, a pressure piston 22, and a cylinder piston 23. The master cylinder 20 also includes a separation chamber 24 and a servo chamber 25. The separation chamber 24 is connected to a stroke simulator SS via a cut valve SGH. The pressure piston 22 is located upstream of the servo chamber 25, and the cylinder piston 23 is located downstream of it.

The operation of the brake mechanism shown in Figure 1 is known, so it will be briefly explained below. When the brake pedal 14 is depressed, the operating rod 18 moves toward the master cylinder 20. Pushed by the operating rod 18, the input piston 21 enters the separation chamber 24.

The hydraulic pressure in the separation chamber 24 is transmitted to the stroke simulator SS via the cut valve SGH. The stroke simulator SS houses a piston and a spring inside. As the brake pedal 14 is depressed, the piston in the stroke simulator SS is pushed. This generates a reaction force in the spring. This reaction force creates a brake feel.

The stroke sensor 16 detects the amount of operation of the brake pedal 14. The amount of operation detected by the stroke sensor 16 is sent to the equipment control unit 100G (see Figure 2) of the upstream brake controller 100. The equipment control unit 100G generates a drive command (e.g., a PWM signal) corresponding to the amount of operation of the brake pedal 14. In response to the drive command, the inverter INV1 operates, supplying power to the motor M1.

As shown in FIG. 1, when motor M1 is driven, hydraulic pressure is applied to rear wheel brake mechanism 50B. Hydraulic pressure is also applied to servo chamber 25 of master cylinder 20 via solenoid valve SLM2. This pushes cylinder piston 23. As cylinder piston 23 moves, hydraulic pressure is also applied to front wheel brake mechanism 50A.

The solenoid valves SLM1 and SLM2 of the upstream brake mechanism 10 are composed of, for example, linear solenoids. The opening of the linear solenoid valves is adjusted according to the supplied current. As illustrated in FIG. 2, the equipment control unit 100G of the upstream brake controller 100 sends a command current value to the PWM controllers PWM1 and PWM2. The PWM controllers PWM1 and PWM2 supply a current according to the command current value to the solenoid valves SLM1 and SLM2.

Cut valve SGH is a so-called normally closed valve, and is closed when no current is supplied. Cut valve SSA is a so-called normally open valve, and is open when no current is supplied.

For example, in the event of a power failure, the normally closed cut valve SGH is closed. In other words, the hydraulic pressure transmission path from the brake pedal 14 to the stroke simulator SS is blocked by the cut valve SGH. When the brake pedal 14 is depressed in this state, the pressure piston 22 is pressed. Furthermore, the advancement of the pressure piston 22 pressurizes the servo chamber 25, which in turn pressurizes the cylinder piston 23. This applies hydraulic pressure to the front wheel brake mechanism 50A.

The upstream brake mechanism 10 is equipped with hydraulic sensors Sgap and Ssrv. The hydraulic sensor Sgap is installed between the separation chamber 24 and the cut valve SGH. The hydraulic sensor Ssrv is installed between the pump P1 and the solenoid valves SLM2 and SM2. The hydraulic pressure values detected by the hydraulic sensors Sgap and Ssrv are sent to the equipment control unit 100G and the abnormality determination unit 100H of the upstream brake controller 100 (see Figure 2).

<Upstream brake controller>
As illustrated in Fig. 1, the upstream brake controller 100 is configured, for example, by a computer. The upstream brake controller 100 includes a CPU 100A as an arithmetic unit and a control unit. The upstream brake controller 100 also includes a RAM 100B, a ROM 100C, and a storage 100D as memory units. The upstream brake controller 100 also includes an input/output controller 100E as an interface unit with peripheral devices. These units are connected by an internal bus 100F.

For example, when the CPU 100A executes the brake control program stored in the storage 100D, functional modules such as those illustrated in FIG. 2 are constructed in the upstream brake controller 100. That is, the upstream brake controller 100 includes an equipment control unit 100G, an abnormality determination unit 100H, and a switch operation unit 100I.

The device control unit 100G controls various actuators of the upstream brake mechanism 10. For example, the device control unit 100G controls the operation of the solenoid valves SLM1 and SLM2, the cut valves SSA and SGH, and the motor M1.

The abnormality determination unit 100H determines whether or not there is an abnormality in the above actuator based on the hydraulic pressure values detected by the hydraulic pressure sensors Ssrv and Sgap during the self-check described below. Details of the self-check will be described later.

The switch operation unit 100I is capable of turning on and off the main switches SW1 and SW3 of the upstream main power lines UML1 and UML2. During the self-check described below, the on/off status of the main switches SW1 and SW3 is determined based on the voltages Vaux and Vbkup of the main power supply 60 and backup power supply 70, respectively. Details of this will be described later.

<Downstream braking system>
Referring to FIG. 1, the downstream braking system includes a downstream braking mechanism 50 and a downstream brake controller 110 .

The downstream brake mechanism 50 distributes the hydraulic pressure generated by the upstream brake mechanism 10 to each wheel. The downstream brake mechanism 50 is divided into a front brake mechanism 50A and a rear brake mechanism 50B. The front brake mechanism 50A includes a reservoir RS1, brake parts Bfr and Bfl, and multiple actuators. As actuators, the front brake mechanism 50A includes a motor M2, a pump P2, a solenoid valve SM1, pressure holding solenoid valves SFRH and SFLH, and pressure reducing solenoid valves SFRR and SFLR. Furthermore, the front brake mechanism 50A includes hydraulic sensors Smc, Sfr, and Sfl.

The rear wheel brake mechanism 50B includes a reservoir RS2, brake parts Brr and Brl, and multiple actuators. As actuators, the rear wheel brake mechanism 50B includes a motor M3, a pump P3, a solenoid valve SM2, pressure holding solenoid valves SRRH and SRLH, and pressure reducing solenoid valves SRRR and SRLR. The rear wheel brake mechanism 50B also includes hydraulic sensors Srr and Srl.

Solenoid valves SM1 and SM2 are provided at the most upstream position of the downstream brake mechanism 50. Solenoid valves SM1 and SM2 are composed of, for example, linear solenoids.

The holding solenoid valves SFRH, SFLH, SRRH, and SRLH are, for example, so-called on/off type solenoids that can be in two states: closed and open. The holding solenoid valves SFRH, SFLH, SRRH, and SRLH are normally open solenoids that are open when demagnetized and no current is supplied.

In the symbol for a holding solenoid valve, the first letter, S, indicates a solenoid valve. The second letter, F/R, indicates front/rear. The third letter, R/L, indicates right/left. Furthermore, the last letter, H, indicates that it is a holding type solenoid valve. For example, the holding solenoid valve SFRH is a solenoid valve (S) located on the front right wheel (FR) and is a holding type (H).

The pressure-reducing solenoid valves SFRR, SFLR, SRRR, and SRLR are, for example, on/off type solenoids. The pressure-reducing solenoid valves SFRR, SFLR, SRRR, and SRLR are normally closed solenoids that are closed when demagnetized.

The first three letters of the symbol for a pressure reducing solenoid valve are determined based on the same definition as for a holding solenoid valve. The R at the end indicates that it is a pressure reducing solenoid valve.

Brake parts Bfr, Bfl, Brr, and Brl are supplied with hydraulic pressure via holding solenoid valves SFRH, SFLH, SRRH, and SRLH. Brake parts Bfr, Bfl, Brr, and Brl are, for example, disc brakes.

When current is supplied to the holding solenoid valves SFRH, SFLH, SRRH, and SRLH, the holding solenoid valves SFRH, SFLH, SRRH, and SRLH are closed. As a result, hydraulic pressure applied to the brake parts Bfr, Bfl, Brr, and Brl is maintained.

When current is supplied to pressure-reducing solenoid valves SFRR, SFLR, SRRR, and SRLR, they open. This reduces the hydraulic pressure applied to brake parts Bfr, Bfl, Brr, and Brl. Brake fluid sent from pressure-reducing solenoid valves SFRR, SFLR, SRRR, and SRLR is temporarily stored in reservoirs RS1 and RS2. Furthermore, pumps P2 and P3 return the brake fluid from reservoirs RS1 and RS2 to the upstream brake mechanism 10.

The downstream brake mechanism 50 is equipped with hydraulic sensors Smc, Sfr, Sfl, Srr, and Srl. The hydraulic sensor Smc is located upstream of the solenoid valve SM1. The hydraulic sensor Smc detects the hydraulic pressure at the most upstream point of the front wheel brake mechanism 50A. The hydraulic sensors Sfr, Sfl, Srr, and Srl detect the hydraulic pressure applied to the brake parts Bfr, Bfl, Brr, and Brl, respectively. The hydraulic pressure values detected by these hydraulic sensors Smc, Sfr, Sfl, Srr, and Srl are sent to the downstream brake controller 110 (see Figure 2). More specifically, the hydraulic pressure values are sent to the equipment control unit 110G and the abnormality determination unit 110H.

<Downstream brake controller>
1, the downstream brake controller 110 is configured by, for example, a computer. Similar to the upstream brake controller 100, the downstream brake controller 110 includes a CPU 110A, a RAM 110B, a ROM 110C, a storage 110D, and an input/output controller 110E. These devices are connected by an internal bus 110F.

For example, when the CPU 110A executes the brake control program stored in the storage 110D, functional modules such as those illustrated in FIG. 2 are constructed in the downstream brake controller 110. That is, the downstream brake controller 110 includes an equipment control unit 110G, an abnormality determination unit 110H, and a switch operation unit 110I.

The device control unit 110G controls various actuators of the downstream brake mechanism 50. For example, the device control unit 110G controls the operation of linear solenoid valves SM1 and SM2, holding solenoid valves SFRH, SFLH, SRRH, and SRLH, pressure-reducing solenoid valves SFRR, SFLR, SRRR, and SRLR, and motors M2 and M3.

During the self-check described below, the abnormality determination unit 110H determines whether or not there is an abnormality in the above actuators based on the hydraulic pressure values detected by the hydraulic pressure sensors Smc, Sfr, Sfl, Srr, and Srl. Details of the self-check will be described later.

The switch operation unit 110I is capable of turning on and off the main switches SW5 and SW7 of the downstream main power lines LML1 and LML2. During the self-check described below, the on/off status of the main switches SW5 and SW7 is determined based on the voltages Vaux and Vbkup of the main power supply 60 and backup power supply 70, respectively. Details of this will be described later.

<Power supply configuration>
2 , the vehicle brake device according to this embodiment includes a main power supply 60 and a backup power supply 70. The main power supply 60 is, for example, an auxiliary battery mounted on the vehicle. A DC/DC converter may be provided between the main power supply 60 and the upstream brake mechanism 10 and the downstream brake mechanism 50.

The backup power supply 70 is composed of, for example, a capacitor cell. The backup power supply 70 is charged to full capacity when the vehicle is started. When the vehicle stops running, the vehicle comes to a stop, and the driving control system is turned off, the backup power supply 70 is discharged until the charge level reaches zero.

For example, the backup power supply 70 can be connected to a resistor (not shown) via a switch or the like. In conventional brake systems, this resistor is used to discharge the backup power supply 70. The backup power supply 70 is discharged until its charge level reaches zero. In this way, the power of the backup power supply 70 would conventionally be wasted after driving has ended. As will be described later, in the vehicle brake system according to this embodiment, this power that would previously have been wasted is used for self-checks of the upstream brake mechanism 10 and the downstream brake mechanism 50.

The power supply controller 80 manages and controls the main power supply 60 and backup power supply 70. The power supply controller 80 is composed of, for example, a computer. Like the upstream brake controller 100 and downstream brake controller 110, the power supply controller 80 is equipped with devices such as a CPU, RAM, ROM, storage, and input/output controller (not shown).

When the CPU executes the power control program stored in the storage of the power supply controller 80, functional modules such as those shown in Figure 2 are constructed in the power supply controller 80. That is, the power supply controller 80 includes a main power supply management unit 80A, a backup power supply management unit 80B, and a switch operation unit 80C.

The main power supply management unit 80A receives the current and voltage values of the main power supply 60 from the current sensor 62 and voltage sensor 64. From these detected values, the main power supply management unit 80A calculates, for example, the SOC (State of Charge) of the main power supply 60.

The backup power supply management unit 80B receives the current and voltage values of the backup power supply 70 from the current sensor 72 and voltage sensor 74. From these detected values, the backup power supply management unit 80B calculates the SOC of the backup power supply 70.

The switch operation unit 80C is capable of turning on and off the backup switches SW2 and SW4 of the upstream backup power lines UBL1 and UBL2. The switch operation unit 80C is also capable of turning on and off the backup switches SW6 and SW8 of the downstream backup power lines LBL1 and LBL2. The switch operation unit 80C is also capable of making switching decisions to switch the backup switches SW2, SW4, SW6, and SW8 from the off state to the on state.

The switching decision is made when the vehicle has finished traveling. "End of vehicle traveling" refers to the vehicle coming to a stop and the cruise control system (not shown) being turned off. For example, the vehicle has finished traveling when the shift position is set to P and electrical connection between the large-capacity battery and the rotating electrical machine (drive source) is cut off. This end of traveling is also referred to as "IG-OFF" in Figure 3.

When the electrical connection between the large-capacity battery and the drive source is interrupted, the driving control system sends a driving end notification to the power supply controller 80. This driving end notification triggers the execution of the self-check flow (see Figure 3). Details of the self-check flow will be described later.

<Circuit configuration>
2, the main power supply 60 and the backup power supply 70 are electrically connected to the upstream brake system and the downstream brake system. As means for this connection, the vehicle brake device includes upstream main power lines UML1 and UML2 and upstream backup power lines UBL1 and UBL2. The vehicle brake device also includes downstream main power lines LML1 and LML2 and downstream backup power lines LBL1 and LBL2.

The upstream main power line UML1 includes a main power cable 91 and a main switch SW1. The main power cable 91 connects the main power supply 60 with the actuators of the upstream brake mechanism 10 and the upstream brake controller 100. Actuators to be connected include solenoid valves SLM1 and SLM2 and cut valves SSA and SGH. The main switch SW1 is provided on the main power cable 91.

The upstream main power line UML2 includes a main power cable 93 and a main switch SW3. The main power cable 93 connects the main power supply 60 and the inverter INV1. The main switch SW3 is provided on the main power cable 93.

The main switches SW1 and SW3 are turned on/off by the switch operating unit 100I of the upstream brake controller 100.

The upstream backup power line UBL1 is a power line that replaces the upstream main power line UML1. The upstream backup power line UBL1 includes a backup power cable 92 and a backup switch SW2. The backup power cable 92 connects the backup power source 70 with the actuators of the upstream brake mechanism 10 and the upstream brake controller 100. The actuators to be connected include solenoid valves SLM1 and SLM2 and cut valves SSA and SGH. The backup switch SW2 is provided on the backup power cable 92.

The upstream backup power line UBL2 is a power line that replaces the upstream main power line UML2. The upstream backup power line UBL2 includes a backup power cable 94 and a backup switch SW4. The backup power cable 94 connects the backup power supply 70 and the inverter INV1. The backup switch SW4 is provided on the backup power cable 94.

Backup switches SW2 and SW4 are turned on/off by switch operation unit 80C of power supply controller 80.

In this way, the upstream brake mechanism 10 and the upstream brake controller 100 are connected to both the main power supply 60 and the backup power supply 70. As described below, the power supply that supplies power to the upstream brake mechanism 10 and the upstream brake controller 100 is selected by turning the main switches SW1 and SW3 and the backup switches SW2 and SW4 on and off.

The downstream main power line LML1 includes a main power cable 95 and a main switch SW5. The main power cable 95 connects the main power supply 60 with the actuators of the downstream brake mechanism 50 and the downstream brake controller 110. The actuators to be connected include solenoid valves SM1, SM2, SFRH, SFRR, SFLH, SFLR, SRRH, SRRR, SRLH, and SRLR. The main switch SW5 is provided on the main power cable 95.

The downstream main power line LML2 includes a main power cable 97 and a main switch SW7. The main power cable 97 connects the main power supply 60 to the inverters INV2 and INV3. The main switch SW7 is provided on the main power cable 97.

Main switches SW5 and SW7 are turned on/off by switch operating unit 110I of downstream brake controller 110.

The downstream backup power line LBL1 is a power line that replaces the downstream main power line LML1. The downstream backup power line LBL1 includes a backup power cable 96 and a backup switch SW6. The backup power cable 96 connects the backup power source 70 with the actuators of the downstream brake mechanism 50 and the downstream brake controller 110. The actuators to be connected include solenoid valves SM1, SM2, SFRH, SFRR, SFLH, SFLR, SRRH, SRRR, SRLH, and SRLR. The backup switch SW6 is provided on the backup power cable 96.

The downstream backup power line LBL2 is a power line that replaces the downstream main power line LML2. The downstream backup power line LBL2 includes a backup power cable 98 and a backup switch SW8. The backup power cable 98 connects the backup power supply 70 to the inverters INV2 and INV3. The backup switch SW8 is provided on the backup power cable 98.

Backup switches SW6 and SW8 are turned on/off by switch operation unit 80C of power supply controller 80.

In this way, the downstream brake mechanism 50 and downstream brake controller 110 are connected to both the main power supply 60 and the backup power supply 70. As described below, the power supply that supplies power to the downstream brake mechanism 50 and downstream brake controller 110 is selected by turning the main switches SW5 and SW7 and the backup switches SW6 and SW8 on and off.

<Backup power connection while driving>
Except when the main power supply 60 fails or during a self-check, which will be described later, the main switches SW1, SW3, SW5, and SW7 are maintained in the on state. In contrast, the backup switches SW2, SW4, SW6, and SW8 are maintained in the off state.

If the main power supply 60 fails while the vehicle is running, the switch operation unit 80C of the power supply controller 80 switches to the backup power supply 70 as the power supply source. Before making this switch, the switch operation unit 80C checks whether the driving control system (not shown) is on.

When the driving control system is in the ON state, the switch operation unit 80C switches the backup switches SW2 and SW4 from the OFF state to the ON state among the backup switches SW2, SW4, SW6, and SW8. This supplies power from the backup power supply 70 to the upstream brake mechanism 10 and the upstream brake controller 100.

Meanwhile, backup switches SW6 and SW8 remain in the off state. This prevents power from being supplied from the backup power supply 70 to the downstream brake mechanism 50 and downstream brake controller 110. As a result, the upstream brake mechanism 10 and upstream brake controller 100 are secured.

Referring to FIG. 1, in a shut-off state where no power is supplied to the downstream brake mechanism 50, the normally open solenoid valves SM1 and SM2 and the holding solenoid valves SFRH, SFLH, SRRH, and SRLH are open. Also, in a shut-off state, the normally closed pressure reducing solenoid valves SFRR, SFLR, SRRR, and SRLR are closed. Therefore, the hydraulic pressure of the upstream brake mechanism 10 is applied to the brake parts Bfr, Bfl, Brr, and Brl via the solenoid valves SM1 and SM2 and the holding solenoid valves SFRH, SFLH, SRRH, and SRLH.

<Self-check>
The vehicle brake device according to this embodiment is capable of performing a self-check on the upstream brake mechanism 10 and the downstream brake mechanism 50. In the self-check, the operation of each actuator of the upstream brake mechanism 10 and the downstream brake mechanism 50 is confirmed.

Because the upstream brake mechanism 10 and downstream brake mechanism 50 have multiple actuators, some of the self-checks are illustrated below. Referring to Figures 1 and 2, for example, for the upstream brake mechanism 10, the equipment control unit 100G of the upstream brake controller 100 sends a drive command to the inverter INV1. After the command is sent, the abnormality determination unit 100H measures the hydraulic pressure value detected by the hydraulic pressure sensor Ssrv. If the hydraulic pressure value of the hydraulic pressure sensor Ssrv does not increase within a predetermined time, the abnormality determination unit 100H determines that the pump P1 is malfunctioning.

Furthermore, with regard to the downstream brake mechanism 50, when the pump P1 is driven, the device control unit 110G of the downstream brake controller 110 supplies current to (closes) the holding solenoid valves SFRH, SFLH, SRRH, and SRLH. Then, the device control unit 100G of the upstream brake controller 100 increases the rotation speed of the pump P1.

At this time, the abnormality determination unit 110H measures the oil pressure values detected by the oil pressure sensors Sfr, Sfl, Srr, and Srl. If the oil pressure value increases at any of the oil pressure sensors Sfr, Sfl, Srr, and Srl (for example, oil pressure sensor Sfr), it determines that the holding solenoid valve SFRH, located upstream of the oil pressure sensor Sfr, is malfunctioning (not completely closed).

<Self-check flow>
3 illustrates a flowchart of a self-check according to this embodiment. This flow is executed when the vehicle has finished traveling. As described above, when the vehicle stops and the cruise control system (not shown) is turned off (IG-OFF), a cruise end notification is sent from the cruise control system to the power supply controller 80. This cruise end notification triggers the execution of the self-check flow illustrated in FIG. 3.

In the first half of the self-check flow, a switching determination is made for the backup switches SW2, SW4, SW6, and SW8 (S10). The switching determination determines whether the backup switches SW2, SW4, SW6, and SW8 should be switched from the OFF state to the ON state.

First, the switch operation unit 80C determines whether the backup power supply 70 is fully charged as a switching determination. The switch operation unit 80C obtains the SOCbkup, which is the charging rate of the backup power supply 70, from the backup power supply management unit 80B. It then determines whether the charging rate SOCbkup is equal to or greater than the full charging rate SOCmax (S10).

If the charging rate SOCbkup of the backup power supply 70 is less than the full charging rate SOCmax, power supply switching is not performed and a self-check is performed by the device control units 100G, 110G (S28). At this time, power is supplied from the main power supply 60 to the upstream brake mechanism 10, upstream brake controller 100, downstream brake mechanism 50, and downstream brake controller 110.

If, in step S10, the charging rate SOCbkup of the backup power supply 70 is equal to or greater than the full charging rate SOCmax, the switch operation unit 80C switches the backup switches SW2 and SW6 from the OFF state to the ON state (S12). This switching connects the actuators of the upstream brake mechanism 10 and the downstream brake mechanism 50, except for the motors M1, M2, and M3, to the backup power supply 70. The upstream brake controller 100 and the downstream brake controller 110 are also connected to the backup power supply 70.

Furthermore, the switch operation unit 80C switches the backup switches SW4 and SW8 from the OFF state to the ON state (S14). This switching connects the motors M1, M2, and M3 to the backup power supply 70 via the inverters INV1, INV2, and INV3.

Next, the switch operation units 100I, 110I of the upstream brake controller 100 and the downstream brake controller 110 acquire the voltage values Vaux, Vbkup of the main power supply 60 and the backup power supply 70 from the voltage sensors 64, 74. Furthermore, the switch operation units 100I, 110I determine whether the voltage value Vaux of the main power supply 60 exceeds the voltage value Vbkup of the backup power supply 70 (S16).

In step S16, if Vaux≦Vbkup, no power is supplied from the main power supply 60, and therefore the main switches SW1, SW3, SW5, and SW7 remain on. After that, the equipment control units 100G, 110G and abnormality determination units 100H, 110H of the upstream brake controller 100 and downstream brake controller 110 perform the self-check described above (S22).

On the other hand, if Vaux > Vbkup, the upstream brake mechanism 10, upstream brake controller 100, downstream brake mechanism 50, and downstream brake controller 110 are supplied with power from the main power supply 60, not from the backup power supply 70. Therefore, the switch operation units 100I and 110I of the upstream brake controller 100 and downstream brake controller 110 switch the main switches SW1, SW3, SW5, and SW7 from the ON state to the OFF state (S18).

In this way, the power supply source to the upstream brake mechanism 10, upstream brake controller 100, downstream brake mechanism 50, and downstream brake controller 110 switches from the main power supply 60 to the backup power supply 70. After that, the equipment control units 100G, 110G and abnormality determination units 100H, 110H of the upstream brake controller 100 and downstream brake controller 110 perform the self-check described above (S20).

When the self-check is completed in step S20, the switch operation units 100I, 110I of the upstream brake controller 100 and the downstream brake controller 110 switch the main switches SW1, SW3, SW5, and SW7 from the OFF state to the ON state (S24).

Furthermore, the switch operation unit 80C of the power supply controller 80 switches the backup switches SW2, SW4, SW6, and SW8 from the ON state to the OFF state (S26).

When the self-check flow in Figure 3 is completed, the backup power supply management unit 80B of the power supply controller 80 determines whether the backup power supply 70 has been fully discharged. That is, the backup power supply management unit 80B calculates the SOC of the backup power supply 70. If the SOC of the backup power supply 70 is higher than 0%, the switch operation unit 80C connects the backup power supply 70 to a resistor (not shown). This causes the backup power supply 70 to discharge until its charge level reaches zero.

As described above, in the vehicle brake system according to this embodiment, by providing downstream backup power lines LBL1 and LBL2, power can also be supplied from the backup power source 70 to the downstream brake mechanism 50 and downstream brake controller 110.

In addition, the period during which power is supplied from the backup power source 70 to the downstream brake mechanism 50 and downstream brake controller 110 is determined after the vehicle has stopped traveling. Therefore, while the vehicle is traveling, power is prevented from flowing from the backup power source 70 to the downstream brake mechanism 50 and downstream brake controller 110. As a result, backup power is ensured for the upstream brake mechanism 10 and upstream brake controller 100 while the vehicle is traveling.

Note that the upstream brake mechanism 10 and downstream brake mechanism 50 have a wide variety of actuators, and the capacity of the backup power supply 70 may make it difficult to complete the self-check. Therefore, certain actuators may be excluded from the self-check.

For example, motors M2 and M3 of the downstream brake mechanism 50 are excluded from the self-check. For example, in step S14 of Figure 3, the on/off switching of backup switch SW8 is omitted. In other words, backup switch SW8 is maintained in the off state. As a result, motors M2 and M3 do not receive power from backup power supply 70. In other words, motors M2 and M3, which consume relatively large amounts of power among the actuators, are excluded from the power supply destinations of backup power supply 70. This makes it possible to more reliably perform self-checks using backup power supply 70 as a power source.

10 upstream brake mechanism, 14 brake pedal, 50 downstream brake mechanism, 60 main power supply, 70 backup power supply, 80 power supply controller, 80A main power supply management unit, 80B backup power supply management unit, 80C power supply controller switch operation unit, 91, 93, 95, 97 main power cable, 92, 94, 96, 98 backup power cable, 100 upstream brake controller, 100I upstream brake controller switch operation unit, 110 downstream brake controller, 110I downstream brake controller switch operation unit, LBL1, LBL2 downstream backup power lines, LML1, LML2 downstream main power lines, SW1, SW3, SW5, SW7 main switches, SW2, SW4, SW6, SW8 backup switches, UBL1, UBL2 upstream backup power lines, UML1, UML2 upstream main power lines.

Claims (4)

an upstream brake mechanism that generates hydraulic pressure based on the amount of operation of the brake pedal;
a downstream brake mechanism that distributes hydraulic pressure generated by the upstream brake mechanism to brake pressures of the respective wheels;
an upstream power line connecting a backup power source to the upstream brake mechanism;
a downstream power line including a backup power cable connecting the backup power source and the downstream brake mechanism, and a backup switch provided on the backup power cable;
a power supply controller including a switch operation unit capable of operating the backup switch;
Equipped with
the switch operation unit executes a switching determination to determine whether to switch the backup switch from an off state to an on state;
The switching determination is performed when the vehicle stops and the driving control system is turned off.
Vehicle braking system. 2. A vehicle brake device according to claim 1,
the power supply controller includes a management unit that calculates an SOC of the backup power supply;
The switch operation unit determines whether the backup power supply is fully charged or not as the switching determination.
Vehicle braking system. 3. A vehicle brake device according to claim 2,
a main power line including a main power cable connecting a main power source and the downstream brake mechanism, and a main switch provided on the main power cable;
a downstream brake controller operable to operate the main switch;
Equipped with
When the voltage of the main power supply exceeds the voltage of the backup power supply, the downstream brake controller switches the main switch from an on state to an off state when the backup switch is switched from an off state to an on state.
Vehicle braking system. A vehicle brake device according to any one of claims 1 to 3,
the backup power source is a capacitor cell;
When the vehicle stops and the driving control system is turned off, the power supply controller discharges the capacitor cell until the charge amount becomes zero.
Vehicle braking system.