JP6598035B2 - Braking device for vehicle - Google Patents

Description

  The present invention relates to a vehicle braking device, and more particularly, to a vehicle braking device including an electric brake means capable of braking a vehicle by driving a motor, and a main power supply and an auxiliary power supply capable of supplying electric power to the electric brake means.

2. Description of the Related Art Conventionally, a brake system that electronically controls the braking force of each wheel in order to apply an optimal braking force to a vehicle according to a traveling state is known. In this electronically controlled brake system, the solenoid valve is controlled so that the wheel cylinder pressure of each wheel becomes the target brake fluid pressure calculated based on the depression amount (for example, stroke) of the brake pedal by the occupant.
Such an electronically controlled brake system uses a pump for increasing the brake fluid pressure, an electromagnetic valve for adjusting the flow of the brake fluid, and the like. These pumps and the electromagnetic valve are driven by a battery as a main power source. ing. Therefore, when the power from the battery is interrupted for some reason, the necessary braking force (deceleration) cannot be ensured.
In view of this, a technique has been proposed in which a backup auxiliary power supply in the event of a main power supply failure is provided in addition to the pre-equipped main power supply.

A capacitor, which is a passive element, can store electric power efficiently, and is hardly used as an auxiliary power source for backup because it is difficult for electrode materials to be deteriorated by charging and discharging.
The vehicle braking device of Patent Document 1 includes a battery that is a main power source, a DLC (capacitor) that is an auxiliary power source, an electric brake booster, and a power source switching that switches an electric power supply path to the electric brake booster. And when the DLC power remaining capacity falls below a predetermined remaining threshold, the power remaining capacity is reduced by decreasing the current value supplied to the electric brake booster as the power remaining capacity decreases. This is intended to reduce the sense of incongruity that accompanies the treading force fluctuation at the time when becomes zero.

In recent years, driving support systems that avoid collision with obstacles are known.
This collision avoidance support system includes a peripheral detection sensor (camera sensor, radar sensor, or the like) that can detect an obstacle ahead of the vehicle, and TTC (corresponding to a time until the host vehicle collides with an obstacle such as a preceding vehicle). Time To Collision) is compared with a predetermined judgment threshold, and when a collision can be avoided by a normal braking operation by the occupant, an audible warning is given to the occupant, and collision avoidance is possible by emergency braking by the occupant. When collision avoidance is physically unavoidable, the vehicle performs automatic brake control that independently activates an electronically controlled brake system.

JP 2010-120522 A

When a backup auxiliary power supply is provided in the vehicle, it is possible to supply power to the electronically controlled brake system by supplying power from the auxiliary power supply when the main power supply fails.
However, power supply by the auxiliary power supply is generally set to a storage capacity smaller than that of the main power supply for the purpose of emergency response, and continuous use for a long time is difficult.
In particular, a capacitor using the phenomenon of charge adhesion and detachment from the electrode surface is inferior in storage capacity per mass compared to a secondary battery because charge accumulation is limited to the surface of the electrode material.
Therefore, when the main power supply is abnormal, the occupant is notified by the lighting of the indicator lamp on the instrument panel. There is a risk of reducing the power of the power supply.

Moreover, in order to operate the electronically controlled brake system to brake the vehicle, a minimum power (for example, 6V) for starting the motor of the electric brake booster is required.
In other words, even if the collision avoidance support system is installed in the vehicle from the viewpoint of ensuring safety, if the occupant is delayed in recognizing the failure of the main power supply, the reserved power that can be supplied from the auxiliary power As a result, the power that can be supplied from the auxiliary power source may decrease.

  An object of the present invention is to provide a vehicle braking device or the like that can suppress a decrease in the amount of reserved electric power of an auxiliary power source while early recognition of a main power source failure by an occupant.

The vehicle braking device according to claim 1 is an electric brake means capable of braking the vehicle by driving a motor, a main power supply capable of supplying electric power to the electric brake means, and an auxiliary power supply capable of supplying electric power to the electric brake means. And a control device capable of controlling the power supplied to the electric brake means, comprising: a power supply state detection means capable of detecting a decrease in function or a stop of the main power supply; and the control means A main power supply that sets a target power supply amount to the electric brake means corresponding to the target deceleration of the vehicle, and that can detect the deterioration or stoppage of the main power supply by the power supply state detection means and can supply the main power supply when available power is not less than the target amount of power supply, without power supply from the auxiliary power source while correcting the target power amount in the decreasing direction, the power supply state detection means When the main power supply suppliable power that can be supplied by the main power supply is less than the target power supply amount, the target power supply amount is corrected in a decreasing direction and the main power supply It is characterized by supplying power from an auxiliary power source .

Since this vehicle braking device has a power supply state detection means capable of detecting a deterioration or stop of the function of the main power supply, it is possible to appropriately detect a failure state of the main power supply where power supply cannot be expected from the main power supply. it can.
The control means sets a target power supply amount to the electric brake means corresponding to a target deceleration of the vehicle, and supplies the target power supply when the power supply state detection means detects a decrease in function or stop of the main power supply. In order to correct the amount in a decreasing direction, it is possible to suppress a decrease in the power that can be supplied from the auxiliary power supply in anticipation of emergency braking that will occur in the future. The occupant can be made aware of the main power supply failure through the operational feeling associated with the actual deceleration.
When the main power supplyable power that can be supplied by the main power is equal to or greater than the target power supply amount , the main power supplyable power that can be supplied by the main power without supplying power from the auxiliary power supply is the target power. When the amount is less than the supply amount, power is supplied from the main power supply and the auxiliary power supply, so that it is possible to suppress a decrease in power that can be supplied from the auxiliary power supply.

The invention of claim 2 is characterized in that, in the invention of claim 1, the control means feeds power from the auxiliary power supply when the power that can be supplied from the main power supply is smaller than the target power supply amount.
According to this configuration, it is possible to reduce the frequency of supplying power from the auxiliary power source, and to further suppress the decrease in power that can be supplied from the auxiliary power source.

According to a third aspect of the present invention, in the first or second aspect of the invention, the control means performs the braking by the electric brake means only when the power supply state detecting means detects a decrease or stop of the function of the main power supply. It is characterized in that the target power supply amount is corrected in a decreasing direction every time it is displayed.
According to this configuration, the longer the period after the main power failure occurs, the greater the difference between the target deceleration of the vehicle and the actual deceleration can be assured to the occupant. Can be recognized.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the vehicle has a determination unit capable of determining the necessity of emergency braking of the host vehicle, and the control unit is determined by the determination unit. When the necessity of emergency braking is low, the target power supply amount is corrected in a decreasing direction as compared with the case where necessity of emergency braking is high.
According to this configuration, it is possible to suppress a decrease in the power that can be supplied from the auxiliary power supply according to the necessity of emergency braking.

The invention of claim 5 is the invention according to any one of claims 1 to 4, wherein a plurality of wheel cylinders each capable of braking a plurality of wheels and brake fluid corresponding to a depression operation of a brake pedal by an occupant are provided. It has a foot brake mechanism provided with a channel which supplies each to a wheel cylinder, and the above-mentioned electric brake means pressurizes brake fluid supplied to a plurality of above-mentioned wheel cylinders.
According to this configuration, it is possible to suppress a decrease in the power that can be supplied from the auxiliary power supply while ensuring the braking performance of the vehicle by supplementing the braking force corresponding to the decrease in the electric energy with the stepping force of the occupant.

  According to the vehicle braking apparatus of the present invention, the reduction in power that can be supplied from the auxiliary power supply is realized while early recognition of the failure of the main power supply by the occupant through the operation feeling associated with the difference between the target deceleration and the actual deceleration of the vehicle. Can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electric circuit diagram of a vehicle braking device according to a first embodiment. It is a schematic block diagram of the brake-by-wire system in the main power supply mode. It is a map of the pedaling force characteristic which shows the relationship between a stroke and pedaling force. It is a map of the braking characteristic which shows the relationship between pedal effort and deceleration. It is a block diagram of the braking device for vehicles. It is a map which shows the relationship between the number of braking operations, and the correction coefficient K1. It is a map which shows the relationship between a vehicle speed and holding | maintenance electric energy. It is a flowchart which shows an automatic braking control processing procedure. It is a flowchart which shows a basic braking control processing procedure. It is a flowchart which shows the target electric power supply amount correction | amendment processing procedure. It is a flowchart which shows a reserve electric power setting process sequence. It is a modification of the map showing the relationship between the number of braking operations and the correction coefficient K1.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The following description illustrates the present invention applied to a vehicle equipped with an electronically controlled brake-by-wire system, and does not limit the present invention, its application, or its use.

Embodiment 1 of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, the vehicle according to this embodiment includes a vehicle power supply 1, a backup power supply unit 2, a brake-by-wire system 3, a vehicle-side load 4 including an audio, an air conditioner, an electronic device, and the like, an ECU ( Electronic Control Unit) 5 (control means) and the like. This vehicle is, for example, a hybrid vehicle that includes an electric motor and an internal combustion engine (both not shown) as a travel drive source, and regenerative braking that brakes the vehicle by regenerating kinetic energy of the vehicle into electrical energy; Brake regenerative cooperative control for generating a desired braking force in combination with hydraulic braking by the brake-by-wire system 3 is configured to be executable.

First, the vehicle power supply 1 will be described.
The vehicle power source 1 mainly includes a main power source 11 composed of a 12 V vehicle battery, an alternator 12 connected in series to the main power source 11 and capable of generating electric power by driving an internal combustion engine. The main power supply 11 is equipped with a main power supply state sensor 13 that can detect a function deterioration or a function stop of the main power supply 11 via a power supply state of the battery including a state of charge (SOC) and a voltage. The detected power state of the main power supply 11 is indicated by an indicator lamp (hereinafter abbreviated as an indicator) 14 (refer to FIG. 5) mounted on an instrument panel (not shown) disposed on the front side of the passenger compartment. The passenger is notified by the display.
The vehicle power supply 1 is connected to the brake-by-wire system 3 by two lines of a first line L1 having a backup power supply unit 2 interposed in the middle and a second line L2 arranged in parallel with the first circuit L1. Are electrically connected.
A third line L3 branched from the middle of the second line L2 is connected to the vehicle-side load 4.

Next, the backup power supply unit 2 will be described.
The backup power supply unit 2 supplies backup power to the brake-by-wire system 3 when there is a possibility that the operation of the brake-by-wire system 3 may interfere with the operation of the brake-by-wire system 3 such as when the vehicle power supply 1 is abnormal or when the power of the main power supply 11 is reduced. Is an auxiliary power supply unit dedicated to the brake-by-wire system 3 capable of supplying
As shown in FIG. 1, the backup power supply unit 2 includes a capacitor 21 as an auxiliary power supply, a charging circuit unit 22, an auxiliary power supply state sensor 23 that can detect a power supply state including the voltage of the capacitor 21, and the like.

The capacitor 21 is formed of, for example, a capacitor cell group in which cells of an electric double layer capacitor are connected in series and parallel, and is configured to be able to generate a voltage of 12V.
The discharge-side end of the capacitor 21 is connected to the first circuit L1 via a first contact 24 that can be electrically switched between on and off states. A second contact 25 that can be electrically switched between on and off is provided in the middle of the first circuit L1 that corresponds to between the first contact 24 and the vehicle power source 1.
The charging circuit unit 22 is configured to be able to charge the capacitor 21 with the vehicle power supply 1.
The downstream side end of the charging circuit unit 22 is connected to the charging side end of the capacitor 21, and the upstream side end is connected to the upstream side portion of the second contact 25 of the first circuit L <b> 1.
When discharging the power from the capacitor 21, the ECU 5 turns on the first contact 24 and turns off the second contact 25. When the capacitor 21 is charged, the ECU 5 turns off the first contact 24 and turns on the second contact 25, and turns off the first and second contacts 24 and 25 at times other than charging and discharging. The

Next, the brake-by-wire system 3 will be described.
As shown in FIG. 1, the by-wire system 3 electrically opens and closes a power supply control circuit unit 31 to which power is supplied from each of the first and second circuits L1 and L2, a motor 32, and a brake fluid flow path. The possible electromagnetic valves 33 to 36, the control unit 37, and the like are the main components.
The power supply control circuit unit 31 distributes the supplied power to the motor driver 32a, the electromagnetic valve drivers 33a to 36a, and the control unit 37 based on predetermined control conditions.
Specifically, the electric power from the vehicle power source 1 is distributed to the motor 32, the electromagnetic valves 33 to 36 and the control unit 37, and the electric power from the backup power source unit 2 is distributed to the motor 32.

Here, a schematic configuration related to the operation system of the brake-by-wire system 3 will be described.
As shown in FIG. 2, the brake-by-wire system 3 includes an electric motor including a master cylinder 42 that can generate a brake fluid pressure according to the stroke St of the brake pedal 41, a motor 32, and a pump unit that is driven by the motor 32. Brake booster 43 (electric brake means), reaction force generating mechanism 44, brake fluid pressure generated by the master cylinder 42 or the electric brake booster 43, or brake fluid generated by the master cylinder 42 and the electric brake booster 43 Wheel cylinders 45a to 45d that brake the rotation of the front and rear left and right wheels FL, FR, RL, and RR of the vehicle by pressure, a control unit 37, and the like are provided.

The master cylinder 42 includes a first pressure generation chamber 42a and a second pressure generation chamber 42b. The first and second pressure generating chambers 42a and 42b are respectively connected to the reservoir tank 46 and have compression springs therein. The first and second pressure generating chambers 42 a and 42 b are configured to be able to pump substantially the same brake fluid pressure in response to the depression operation of the brake pedal 41.
The first pressure generation chamber 42a communicates with the wheel cylinders 45a and 45b via the openable / closable electromagnetic valve 33, and the second pressure generation chamber 42b communicates with the wheel cylinders 45c and 45d via the openable / closable electromagnetic valve 36. Has been.

As shown in FIG. 2, the pump portion of the electric brake booster 43 communicates with the wheel cylinders 45 a and 45 b via the electromagnetic valve 34 that can be opened and closed, and communicates with the wheel cylinders 45 c and 45 d via the electromagnetic valve 35 that can be opened and closed. Has been. The minimum power E0 that can start the motor 32 of the electric brake booster 43 is, for example, 6V.
The reaction force generation mechanism 44 is connected to a flow path that communicates the first pressure generation chamber 42a and the electromagnetic valve 33. For example, the reaction force generation mechanism 44 is a cylinder, a piston that is slidable in the cylinder, and an urging force that urges the piston. It is formed by means or the like. Accordingly, when the occupant depresses or returns the brake pedal 41, a reaction force (stepping force) having a preset characteristic can be applied to the occupant via the brake pedal 41.

When the main power supply 11 is normal, the control unit 37 closes the solenoid valves 33 and 36 and opens the solenoid valves 34 and 35 according to the control signal input from the ECU 5. At the time of depression, all the solenoid valves 33 to 36 are opened.
In addition, the control unit 37 is configured to execute deceleration control processing and pedaling force control processing by controlling the electric brake booster 43, the reaction force generation mechanism 44, the stroke sensor 47, and the electromagnetic valves 33 to 36. Has been.

The control unit 37 has a pedaling force characteristic map M1 and a braking characteristic map M2.
As shown in FIG. 3, the map M1 is defined by a predetermined function, for example, logarithm.
The control unit 37 sets a pedaling force F corresponding to the target operation reaction force based on the stroke St by the occupant detected by the stroke sensor 47 and the pedaling force characteristic map M1, and outputs an operation command signal corresponding to this to the reaction force generating mechanism 44. Is output.
As shown in FIG. 4, the control unit 37 sets the target deceleration D of the vehicle using the pedal effort F set via the detected stroke St and the braking characteristic map M2, and corresponds to the target deceleration D. The operation command signal is output to the motor 32 (motor driver 32a).
As a result, the wheel cylinders 45a to 45d are driven via the brake fluid pressure, and the braking operation at the deceleration D based on the braking characteristic map M2 is executed.
At the same time, the control unit 37 outputs a control signal related to the stroke St and the target deceleration D to the ECU 5.

Next, the ECU 5 will be described.
The ECU 5 is a main power supply mode that supplies power to the electric brake booster 43 only from the main power supply 11, and first and second power that supply power to the electric brake booster 43 from both the main power supply 11 and the capacitor 21. The auxiliary power supply combined mode can be executed. Specifically, in the main power supply mode, the target power supply amount E required for the operation of the electric brake booster 43 is the main power suppliable power E1 that can be supplied by the main power supply 11 (hereinafter abbreviated as the suppliable power E1). At this time, power corresponding to the target power supply amount E is supplied only from the main power supply 11. The first auxiliary power combined mode is equivalent to the target power supply amount E from both the main power supply 11 and the capacitor 21 when the sum of the supplyable power E1 and the usable power ΔE2 of the capacitor 21 is equal to or greater than the target power supply amount E. In the second auxiliary power supply combined mode, when the sum of the supplyable power E1 and the usable power ΔE2 of the capacitor 21 is less than the target power supply amount E, it can be supplied from both the main power supply 11 and the capacitor 21. Electric power less than the target power supply amount E is supplied.
Note that the usable power ΔE2 of the capacitor 21 is a reserve of the capacitor 21 that is basically not used except during emergency braking from the auxiliary power supplyable power E2 that can be supplied by the capacitor 21 (hereinafter referred to as “suppliable power E2”). The difference is the power E2a.

As shown in FIG. 5, the ECU 5 is electrically connected to the main power supply state sensor 13, the auxiliary power supply state sensor 23, the control unit 37, the wheel speed sensor 61, the periphery detection sensor 62, and the wiper sensor 63. Detection signals and control signals output from these sensors are input.
The wheel speed sensor 61 is configured to be able to detect the wheel speed of each wheel FL, FR, RL, RR. The peripheral detection sensor 62 is constituted by, for example, a radar sensor such as a millimeter wave radar or a laser radar disposed on the front side of the vehicle, or a camera sensor such as a CCD or CMOS, and a so-called obstacle such as a preceding vehicle existing in front of the host vehicle. The relative position (separation distance) and relative speed of the object can be detected. The wiper sensor 63 is configured to be able to detect whether or not the wiper device is operating via a drive current of a wiper device (not shown) that wipes raindrops attached to the front window glass.

The ECU 5 includes a CPU (Central Processing Unit), a ROM, a RAM, an in-side interface, an out-side interface, and the like. Various programs and data are stored in the ROM, and a processing area used when the CPU performs a series of processing is provided in the RAM.
As shown in FIG. 5, the ECU 5 includes a determination unit 51 (determination unit), an automatic brake control unit 52 (automatic brake control unit), a power supply state detection unit 53 (power supply state detection unit), and a target power supply amount setting. Unit 54, target power supply amount correction unit 55, reserved power setting unit 56, and the like.

First, the determination unit 51 will be described.
The determination unit 51 determines the necessity of emergency braking of the host vehicle.
The necessity of emergency braking is the degree of risk that a collision between the host vehicle and an object (obstacle) will occur.
Therefore, the determination unit 51 calculates TTC (Time To Collision) corresponding to the time until the host vehicle collides with an obstacle such as a preceding vehicle. Of the obstacles detected by the surrounding detection sensor 62, the obstacle closest to the host vehicle is determined, and the TTC for this obstacle is calculated.

In addition to the determination of TTC, the determination unit 51 also determines the degree of risk related to an erroneous operation by the occupant. Specifically, the higher the vehicle speed V is, the higher the degree of danger is, and when the road surface μ of the traveling road is a low μ that is lower than a predetermined determination value, the risk is determined to be high. Further, even when the wiper device is operating, it is determined that the degree of danger is high because the field of view of the occupant is deteriorated.
The vehicle speed V is obtained from the slower wheel speed of the left and right driven wheels, and the road surface μ is calculated using the separately obtained vehicle driving force and ground contact load.

Next, the automatic brake control unit 52 will be described.
The automatic brake control unit 52 outputs an operation command signal to the motor 32 (motor driver 32a) based on the TTC determined by the determination unit 51 regardless of the operation of the brake pedal 41 by the occupant. Specifically, when the TTC is equal to or greater than a first threshold value (for example, 4 sec), the collision can be avoided by a normal braking operation by the occupant, so the flag f is set to zero and no control from the vehicle side is executed. If the TTC is less than the first threshold, the flag f is set to 1.
When the TTC is less than the first threshold value and greater than or equal to the second threshold value (for example, 2.3 sec), the collision can be avoided by an emergency braking operation by the occupant. When the TTC is less than the second threshold value, collision avoidance is unavoidable even by an emergency braking operation by the occupant, and therefore the motor 32 is operated to execute automatic braking, which is emergency braking.

Next, the power supply state detection unit 53 and the target power supply amount setting unit 54 will be described.
Based on the detection result of the main power supply state sensor 13, the power supply state detection unit 53 is based on the supplyable power E <b> 1 that the main power supply 11 can supply to the electric brake booster 43 (motor 32) and the detection result of the auxiliary power supply state sensor 23. The capacitor 21 is configured to detect the suppliable electric power E <b> 2 that can be supplied to the electric brake booster 43.
In addition, the power supply state detection unit 53 compares the determination threshold L set in advance with the suppliable power E1, and when the suppliable power E1 is less than the determination threshold L, the main power supply 11 is degraded or stopped ( (Failure state).

The target power supply amount setting unit 54 is a required deceleration required for the electric brake booster 43 to operate based on the target deceleration D input from the control unit 37 and the deceleration D0 that can be generated by the passenger's own pedaling force. D1 is calculated using the following equation (1).
D1 = D−D0 (1)
The deceleration D0 is obtained in advance by experiments or the like based on the maximum pedaling force that can be exhibited by the occupant.
The calculated required deceleration D1 is converted into a braking target torque, and a target power supply amount E required for the operation of the electric brake booster 43 is calculated based on the braking target torque.

Next, the target power supply amount correction unit 55 will be described.
The target power supply amount correction unit 55 corrects the target power supply amount E to be decreased when the power supply state detection unit 53 detects that the main power supply 11 has deteriorated or stopped functioning.
By reducing the amount of power supplied from the capacitor 21, it is possible to lengthen the period during which power can be supplied by the capacitor 21 when the function deterioration or the function stop of the main power supply 11 is detected. Electric power necessary for execution of automatic braking can be secured.

The target power supply amount correction unit 55 corrects the target power supply amount E using the correction coefficients K1 and K2.
As shown in FIG. 6, the target power supply amount correction unit 55 has in advance a map M3 indicating a linear function relationship between the number of braking operations N (times) and the correction coefficient K1 (0 <K1 <1). Yes.
When the automatic brake is in an inoperative state and the collision cannot be avoided by a normal braking operation by the occupant (when f = 1), the depression operation of the brake pedal 41 from the time when the main power supply 11 is detected to be degraded or stopped. K1 is set based on the number of times N, and the target power supply amount E is corrected using the set K1 and the following equation (2).
(1-K1) × E (2)
In this embodiment, the initial value of the correction coefficient K1 is defined as 0.1, and the maximum value is defined as 0.3.
N is reset to zero when the main power supply 11 is no longer degraded or stopped.

Further, the target power supply amount correction unit 55 corrects the target power supply amount E with the correction coefficient K1 as in the following equation (3) when the collision can be avoided by a normal braking operation by the occupant (when f = 0). Correction is performed using the coefficient K2 (0 <K2 <1).
[1- (K1 + K2)] × E (3)
In this embodiment, the correction coefficient K2 is defined as a constant (for example, 0.1).
When the automatic brake is executed by the automatic brake control unit 52, the correction of the target power supply amount E is prohibited.

Next, the reserved power setting unit 56 will be described.
The reserved power setting unit 56 sets the reserved power E2a, which is the lowest residual power of the capacitor 21, as the automatic braking by the automatic brake control unit 52 is in an inoperative state and the necessity of emergency braking determined by the determination unit 51 increases. It is configured to increase.
This is because electric power necessary for execution of automatic braking by the automatic brake control unit 52 is ensured.

The reserved power setting unit 56 sets the reserved power E2a using the correction coefficients K3, K4, K5 and the vehicle speed V.
As indicated by the solid line in FIG. 7, when the road surface μ is larger than the determination threshold, the reserved power setting unit 56 sets the reserved power E2a to be proportional to the vehicle speed V based on the correction coefficient K3 (0 <K3). ing. Specifically, the reserved electric power E2a is calculated using the following equation (4) so that it becomes larger than the minimum electric energy E0 for starting the motor 32 of the electric brake booster 43.
E2a = E0 + K3 × V (4)

As shown by the dotted line in FIG. 7, when the road surface μ is equal to or less than the determination threshold value and the wiper is in an inoperative state, the reserved power E2a uses the following equation (5) based on the correction coefficient K3 and the correction coefficient K4 (1 <K4). Is set to be proportional to the vehicle speed V. This is because the road surface μ is low and the danger level is high.
K4 × (E0 + K3 × V) (5)
As indicated by the one-dot chain line in FIG. 7, when the road surface μ is equal to or less than the determination threshold value and the wiper is in the operating state, the reserved power E2a is expressed by the following equation (6) based on the correction coefficients K3 and K4 and the correction coefficient K5 (1 <K5). Is set to be proportional to the vehicle speed V. This is because the field of view of the occupant is lowered and the danger level is higher.
K4 × K5 × (E0 + K3 × V) (6)
As described above, the higher the degree of danger, that is, the higher the possibility that the automatic brake is executed, the higher the reserved power E2a that is the electric power for executing the automatic brake.
In addition, when the automatic brake is performed by the automatic brake control unit 52, the reserved power E2a is set to the minimum power amount E0.

The ECU 5 determines the usable power ΔE2 of the capacitor 21 that is fed to the electric brake booster 43 based on a normal braking operation by the occupant. The ECU 5 calculates the suppliable power E2 based on the detection result of the auxiliary power supply state sensor 23, and subtracts the reserved power E2a set by the reserved power setting unit 56 from the suppliable power E2, thereby performing normal braking by the occupant. The usable power ΔE2 of the capacitor 21 during operation is calculated.
As a result, electric power necessary for execution of automatic braking by the automatic brake control unit 52 is secured in the capacitor 21.

Next, the automatic braking control processing procedure will be described based on the flowchart of FIG.
Si (i = 1, 2,...) Indicates steps for each process.

As shown in FIG. 8, first, various information is read (S1), and the process proceeds to S2.
In S2, time TTC until the own vehicle collides with an obstacle is calculated, and the process proceeds to S3.
In S3, it is determined whether TTC is less than a first determination threshold value.
As a result of the determination in S3, if TTC is less than the first determination threshold, there is a need for emergency braking, so 1 is substituted for flag f (S4), and the process proceeds to S5.
As a result of the determination in S3, if the TTC is equal to or greater than the first determination threshold, the necessity for emergency braking is extremely low, so zero is substituted for the flag f (S8), and the process returns.

In S5, it is determined whether TTC is less than a second determination threshold value.
As a result of the determination in S5, if TTC is less than the second determination threshold, collision avoidance is unavoidable even by an emergency braking operation by the occupant, so automatic braking by the vehicle is executed (S6) and the process returns.
At this time, the electric brake booster 43 is supplied with electric power E2 including the reserved electric power E2a from the capacitor 21 for automatic braking.
As a result of the determination in S5, when the TTC is equal to or greater than the second determination threshold, a collision can be avoided by an emergency braking operation by the occupant, so the alarm unit 64 is activated (S7) and the process returns.

  Next, the basic braking control processing procedure will be described based on the flowcharts of FIGS. This basic braking control process is executed in parallel with the automatic braking control process.

As shown in FIG. 9, first, various information such as sensor outputs, correction coefficients K1 to K5 and maps M1 to M3 are read (S11), and the process proceeds to S12.
In S12, it is determined whether or not the occupant has depressed the brake pedal 41.
As a result of the determination in S12, when the occupant depresses the brake pedal 41, the target deceleration D is calculated based on the stroke St of the brake pedal 41 and the maps M1 and M2 (S13).
As a result of the determination in S12, if the occupant has not depressed the brake pedal 41, the process proceeds to S29.

In S14, the required deceleration D1 required for the vehicle is calculated using the calculated target deceleration D and the deceleration D0 that the occupant can generate with his / her pedaling force.
In S15, the target power supply amount E required for the operation of the electric brake booster 43 is calculated using the calculated required deceleration D1.
In S16, the suppliable electric power E1 that can be supplied from the main power supply 11 to the electric brake booster 43 is calculated based on the detected power state of the main power supply 11.
In S17, the suppliable electric power E2 that can be supplied from the capacitor 21 to the electric brake booster 43 is calculated based on the detected power state of the capacitor 21.

In S18, it is determined whether the suppliable power E1 is less than the determination threshold L.
As a result of the determination in S18, if the suppliable power E1 is less than the determination threshold L, there is a possibility that the function of the main power supply 11 may be reduced or the function may be stopped. Therefore, after substituting N + 1 for the number of depressions N of the brake pedal 41 (S19 ), The target power supply amount correction process (S20) is executed to correct the target power supply amount E, and the process proceeds to S21.
As a result of the determination in S18, if the suppliable power E1 is greater than or equal to the determination threshold L, the possibility that the function of the main power supply 11 is reduced or stopped is extremely low. S27) While maintaining the target power supply amount E without correction (S28), the process proceeds to S21.

In S21, it is determined whether the suppliable power E1 is less than the target power supply amount E.
As a result of the determination in S21, when the suppliable power E1 is less than the target power supply amount E, power supply from the capacitor 21 is necessary, and the suppliable power E2 decreases, so the reserved power setting process (S22) is executed. The reserved power E2a is set, and the process proceeds to S23.
As a result of the determination in S21, when the suppliable power E1 is equal to or greater than the target power supply amount E, power supply from the capacitor 21 is not necessary and the suppliable power E2 does not decrease, so the main power supply mode is executed (S26), Return.

In S23, it is determined whether or not the total power of the suppliable power E1 and the usable power ΔE2 is equal to or greater than the target power supply amount E.
As a result of the determination in S23, when the total power of the suppliable power E1 and the usable power ΔE2 is equal to or greater than the target power supply amount E, the target power supply amount E can be supplied with the reserved power E2a left in the capacitor 21, The first auxiliary power combined mode for supplying power corresponding to the power supply amount E is executed (S24), and the process returns.
As a result of the determination in S23, when the total power of the suppliable power E1 and the usable power ΔE2 is less than the target power supply amount E, the target power supply amount E cannot be supplied with the reserved power E2a left in the capacitor 21, so the capacitor The second auxiliary power combined mode for supplying power less than the target power supply amount E is executed with the reserved power E2a left at 21 (S25), and the process returns.
In the second auxiliary power combined mode, the electric power supplied to the electric brake booster 43 is lower than the target electric power supply amount E in order to leave the reserve electric power E2a for emergency braking in the capacitor 21, and the braking performance of the electric brake booster 43 is reduced. Is less than the required deceleration D1.
However, since the solenoid valves 33 and 36 are opened, the braking performance is artificially compensated by the braking operation (depression / returning) by the subsequent occupant.

In S29, it is determined whether or not the flag f is zero.
As a result of the determination in S29, when the flag f is zero, the collision can be avoided by the normal braking operation by the occupant, and the process proceeds to S30.
In S30, it is determined whether or not the suppliable power E2 of the capacitor 21 is equal to or higher than a charging threshold (for example, full charge).
As a result of the determination in S30, if the suppliable power E2 of the capacitor 21 is equal to or greater than the charging threshold, the process returns. If the suppliable power E2 of the capacitor 21 is less than the charging threshold, the capacitor 21 is charged (S31), and the return To do.
As a result of the determination in S29, if the flag f is not zero, the routine returns because automatic braking is being executed or there is a need for emergency braking.

Next, the target power supply amount correction processing procedure in S20 will be described.
As shown in the flowchart of FIG. 10, in the target power supply amount correction process, first, in S41, it is determined whether or not the flag f is zero.
As a result of the determination in S41, when the flag f is zero, the braking force can be secured by the braking operation (depression) by the occupant himself and the braking force by the electric brake booster 43 can be reduced. The target power supply amount E is corrected to decrease (S42), and the process ends.
If the flag f is not zero as a result of the determination in S41, the process proceeds to S43.

In S43, it is determined whether or not automatic braking is being performed.
If the result of determination in S43 is that automatic braking is being performed, the degree of danger is high, so the target power supply amount E is not corrected (S44) and the process ends.
If the result of determination in S43 is that automatic braking is not being executed, the target power supply amount E is corrected to decrease using equation (2) (S45), and the process ends.

Next, the reserved power setting process procedure in S22 will be described.
As shown in the flowchart of FIG. 11, in the reserved power setting process, first, in S51, it is determined whether or not the automatic brake is inoperative.
As a result of the determination in S51, if the automatic brake is not activated, the process proceeds to S52 to determine whether or not the road surface μ is low. If the result of determination in S51 is that automatic braking is being performed, the reserved power E2a is set to the minimum power E0 (S57), and the flow proceeds to S58.

If the road surface μ is low as a result of the determination in S52, the process proceeds to S53 to determine whether or not the wiper is operating. As a result of the determination in S52, if the road surface μ is not low, the possibility that the automatic brake is executed is not so high, so the holding power E2a is set using Expression (4) (S56), and the process proceeds to S58. .
As a result of the determination in S53, when the wiper is operating, the field of view is lowered, and there is a high possibility that the automatic brake is executed. Therefore, the reserved power E2a is set using Equation (6) (S54), The process proceeds to S58. If the result of the determination in S53 is that the wiper is not operating, there is a high possibility that the automatic brake will be executed. Therefore, the reserved power E2a is set using equation (5) (S55), and the process proceeds to S58.
In S58, the available power ΔE2 is calculated by subtracting the reserved power E2a from the suppliable power E2, and then the process ends.

Next, functions and effects of the vehicle braking device will be described.
According to the vehicle control apparatus according to the first embodiment, since the power supply state detection unit 53 that can detect the function deterioration or stop of the main power supply 11 is included, it is impossible to expect power supply from the main power supply 11. It is possible to appropriately detect the failure state. The ECU 5 sets a target power supply amount E to the electric brake booster 43 corresponding to the target deceleration D of the vehicle, and when the power state detection unit 53 detects a decrease in function or a stop of the main power source 11, In order to correct the supply amount E in the decreasing direction, the decrease in the amount of electric power E2 that can be supplied from the capacitor 21 can be suppressed by reducing the amount of electric power supplied from the capacitor 21 in anticipation of automatic braking that will occur in the future. The occupant can be made aware of the failure of the main power supply 11 through the operational feeling associated with the difference between the deceleration D and the actual deceleration.

  When the suppliable power E1 that can be supplied from the main power supply 11 is smaller than the target power supply amount E, the ECU 5 supplies power from the capacitor 21, so that the frequency of supplying power from the capacitor 21 can be reduced. A decrease in the suppliable power E2 can be further suppressed.

  Since the ECU 5 corrects the target power supply amount E in a decreasing direction every time braking is performed by the electric brake booster 43, the longer the period after the failure of the main power supply 11, the longer the target deceleration D of the vehicle. And the actual deceleration can be increased, and the occupant can be surely recognized that the main power supply 11 has failed.

  The ECU 5 includes a determination unit 51 that can determine the necessity of emergency braking of the host vehicle, and the ECU 5 sets a target when the necessity of emergency braking is low when the necessity of emergency braking determined by the determination unit 51 is low. Since the electric power supply amount E is corrected in the decreasing direction, the decrease in the electric power E2 that can be supplied from the capacitor 21 can be suppressed according to the necessity of emergency braking.

  A plurality of wheel cylinders 45a to 45d capable of braking each of the wheels FL, FR, RL, and RR, and a flow path for supplying brake fluid to the wheel cylinders 45a to 45d according to the depression operation of the brake pedal 41 by the occupant. In order to pressurize the brake fluid supplied to each of the wheel cylinders 45a to 45d, the electric brake booster 43 compensates the braking force corresponding to the decrease in the electric energy with the occupant's pedaling force. As a result, it is possible to suppress a decrease in the electric power E2 that can be supplied from the capacitor 21 while ensuring the braking performance of the vehicle.

Next, a modified example in which the embodiment is partially changed will be described.
1] In the above-described embodiment, an example in which a capacitor that is a passive element is used as an auxiliary power source has been described. However, a lithium ion battery that is a secondary battery may be used. Moreover, it is also possible to use a normal battery (lead storage battery).

2] In the above embodiment, the example in which the correction coefficient K1 is a variable that increases linearly in proportion to the number of braking operations has been described. However, as shown in FIG. good. Further, a determination threshold value may be provided and switched when the number of braking operations becomes equal to or greater than the determination threshold value.

3] In the above embodiment, an example in which the correction coefficient K2 is a constant has been described. However, a variable that increases in proportion to TTC may be used.

4] In the above embodiment, an example in which one auxiliary power source is provided has been described. However, a plurality of auxiliary power sources may be provided. In this case, the power that can be supplied is detected for each auxiliary power supply, and the total power is handled as the power that can be supplied to the auxiliary power supply.

5] In addition, those skilled in the art can implement the present invention in a form in which various modifications are added to the above-described embodiment or in a form in which each embodiment is combined without departing from the spirit of the present invention. Various modifications are also included.

3 Brake-by-wire system 5 ECU
DESCRIPTION OF SYMBOLS 11 Main power supply 21 Capacitor 32 Motor 41 Brake pedal 43 Electric brake booster 45a-45d Wheel cylinder 53 Power supply state detection part 54 Target power supply amount setting part 55 Target power supply amount correction | amendment part FL, FR, RL, RR Wheel

Claims (5)

Electric brake means capable of braking the vehicle by driving a motor, a main power supply capable of supplying electric power to the electric brake means, an auxiliary power supply capable of supplying electric power to the electric brake means, and electric power supplied to the electric brake means In a vehicle braking device comprising control means capable of controlling
Having power supply state detection means capable of detecting deterioration or stop of the function of the main power supply,
The control means sets a target power supply amount to the electric brake means corresponding to the target deceleration of the vehicle, and the power supply state detection means detects that the function of the main power supply is reduced or stopped, and the main power supply is supplied. When the possible main power supplyable power is equal to or greater than the target power supply amount, the target power supply amount is corrected in a decreasing direction, and power is not supplied from the auxiliary power source, and the power supply state detection means reduces the function of the main power source. Alternatively, when the stoppage is detected and the main power supplyable power that can be supplied by the main power source is less than the target power supply amount, the target power supply amount is corrected in a decreasing direction, and power is supplied from the main power source and the auxiliary power source. A braking device for a vehicle.   2. The vehicular braking apparatus according to claim 1, wherein when the electric power that can be supplied from the main power source is smaller than the target power supply amount, the control unit supplies power from the auxiliary power source. The control means corrects the target power supply amount in a decreasing direction every time braking by the electric brake means is performed only when the power supply state detection means detects a decrease or stop of the function of the main power supply. The vehicle braking device according to claim 1, wherein the vehicle braking device is a vehicle braking device. Having a judging means capable of judging the necessity of emergency braking of the own vehicle;
The control means corrects the target power supply amount in a decreasing direction when the necessity of emergency braking determined by the determination means is low compared to when the necessity of emergency braking is high. The vehicle braking device according to any one of 1 to 3. A plurality of wheel cylinders each capable of braking a plurality of wheels, and a foot brake mechanism including a flow path for supplying brake fluid to each of the plurality of wheel cylinders according to a depression operation of a brake pedal by an occupant,
The vehicular braking apparatus according to any one of claims 1 to 4, wherein the electric brake means pressurizes brake fluid supplied to the plurality of wheel cylinders.

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