JP6579401B2 - Braking device for vehicle - Google Patents

Description

  The present invention relates to a vehicular braking apparatus, and more particularly to a vehicular braking apparatus including an electric brake means capable of braking a vehicle by driving a motor.

  2. Description of the Related Art Conventionally, a brake-by-wire system that electronically controls the braking force of each wheel is known in order to apply an optimal braking force to a vehicle in accordance with a traveling state. In the brake-by-wire 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 a brake-by-wire system is an electric brake means that operates with a battery as a secondary battery as a main power source, and a pump that increases brake fluid pressure, an electromagnetic valve that adjusts the flow of brake fluid, and the like are driven by the power of the battery. The The voltage range (operating voltage) necessary for the operation of the electric brake means is set in advance, and the electric power supplied by the operating voltage is supplied to the pump, the electromagnetic valve, etc. by being transformed in the electric brake means.

  A battery undergoes a chemical reaction in charge and discharge, and its output voltage gradually decreases with a decrease in the amount of stored electricity (remaining battery amount) while maintaining a predetermined value or higher, and rapidly decreases when it becomes less than a predetermined value. In addition, when a large current is output in a short time, the output voltage rapidly decreases. For this reason, when the load on the vehicle equipment is high and the battery outputs a large current or when the remaining amount of the battery is low, the power that can be supplied by the battery is in a state where there is no margin. When such battery supply power is not sufficient, or when a battery failure occurs when the battery power supply is interrupted for other reasons, the electric brake means may not be operated and an optimum braking force may not be obtained.

  In view of this, a technique has been proposed in which a capacitor is provided as an auxiliary power supply for a battery that is equipped in advance in case of such a battery failure. For example, Patent Document 1 discloses a technique for supplying electric power from a capacitor serving as an auxiliary power source to an electric brake booster in a vehicle braking device when a battery fails.

  Capacitors can charge and discharge current efficiently because they accumulate charges on the surfaces of the positive and negative electrodes. Therefore, the capacitor has a higher charge / discharge speed than a battery, and is suitable for input and output of a large current in a short time. In addition, since charging and discharging of the capacitor does not involve a chemical reaction like a battery, there is almost no deterioration due to charging and discharging, and it is suitable for applications in which charging and discharging are repeated.

JP 2010-120522 A

  A vehicle equipped with an electric brake means is required to ensure safety by operating the electric brake means to obtain an optimum braking force even in a situation where the brake operation is continuously performed a plurality of times. . Since this is the same even when the battery fails, it is necessary to increase the storage capacity of the capacitor so that electric power can be continuously supplied from the capacitor a plurality of times. However, the capacitor has a smaller storage capacity per mass than the secondary battery, and it is not easy to increase the storage capacity of the capacitor.

  Therefore, it has been studied to increase the overall storage capacity by providing a plurality of capacitors of limited capacity without increasing the storage capacity of the capacitor itself, and to supply power to the electric brake means by switching the plurality of capacitors. . However, since the total storage capacity of the plurality of capacitors is still limited, when the power supply is continued to some extent, the remaining amount of any capacitor decreases.

  In addition, in order to avoid the occurrence of a capacitor failure or the like during parking, it has been studied to perform control to reduce the remaining amount of the capacitor to a predetermined amount. When the parking period becomes longer, the remaining amount of the capacitor decreases from the predetermined amount due to self-discharge, and any capacitor may not be able to output the operating voltage. When starting the engine in this state, power for starting the engine is output from the battery, so there is a risk that the power supplied to the electric brake means will be insufficient.

  An object of the present invention is to provide a vehicular braking device that can supply electric power from an auxiliary power supply device and obtain an optimum braking force when electric power supplied to an electric brake means is insufficient. .

According to the first aspect of the present invention, an electric brake means capable of braking a vehicle by driving a motor by an occupant's brake operation, a main power source capable of supplying electric power to the electric brake means, and supplying electric power to the electric brake means And a plurality of power storage means together with the main power supply or instead of the main power supply when the required power of the electric brake means is larger than the power that can be supplied by the main power supply. the vehicle braking apparatus and control means for supplying power to the electric brake means from the auxiliary power unit in a first connection mode used alone one of said control means, when starting the engine Is characterized in that the auxiliary power supply is switched from the first connection form to a second connection form in which the plurality of power storage means are connected in series.

According to the above configuration, the vehicular braking device obtains an optimum braking force by supplying electric power from the auxiliary power supply device in the first connection form when the electric power supplied from the main power source to the electric brake means is insufficient. When the engine is started , the auxiliary power supply device is set to the second connection form. Therefore, at the time of starting the engine where the electric power supplied from the main power supply to the electric brake means may be insufficient , the output voltage of the auxiliary power supply device is raised by using the second connection configuration in which a plurality of power storage means are connected in series. Thus, it is possible to supply electric power to the electric brake means from the auxiliary power supply device whose output voltage has been increased.

According to a second aspect of the present invention, an electric brake means capable of braking a vehicle by driving a motor by an occupant's brake operation, a main power supply capable of supplying electric power to the electric brake means, and supplying electric power to the electric brake means And a plurality of power storage means together with the main power supply or instead of the main power supply when the required power of the electric brake means is larger than the power that can be supplied by the main power supply. And a control means for supplying electric power from the auxiliary power supply device to the electric brake means in a first connection form in which one of them is used alone. When the voltage of the means is less than the preset reference voltage, the auxiliary power supply device is used by connecting the plurality of power storage means in series from the first connection configuration. It is characterized in that switching to the second form of connection to.

According to the above configuration, the vehicular braking device obtains an optimum braking force by supplying electric power from the auxiliary power supply device in the first connection form when the electric power supplied from the main power source to the electric brake means is insufficient. When the voltages of the plurality of power storage units are all less than a preset reference voltage, the auxiliary power supply device is set to the second connection form. Accordingly, when the auxiliary power supply apparatus of the first connection form has a problem in supplying power to the electric brake means, the output voltage of the auxiliary power supply apparatus is increased by using the second connection form in which a plurality of power storage means are connected in series. By doing so, it is possible to supply electric power to the electric brake means from the auxiliary power supply device whose output voltage has been increased.

According to a third aspect of the present invention, in the first or second aspect of the present invention, each of the plurality of power storage means is a capacitor, and the control means changes the second connection configuration when the occupant does not perform a brake operation. The capacitor is charged by switching to one connection form.

  According to the above configuration, the overall storage capacity of the capacitors connected in series in the second connection form is smaller than the overall storage capacity when the plurality of capacitors in the first connection form are used individually. Therefore, when there is no brake operation, the amount of power stored in the auxiliary power supply device can be maximized by preparing for the next power supply by switching to the first connection form and charging.

  According to the present invention, when the electric power supplied to the electric brake means is insufficient, it is possible to supply electric power from the auxiliary power supply device and obtain an optimum braking force.

It is a figure which shows the electric power supply system | strain of the vehicle braking device which concerns on an Example. It is a block diagram which shows the control system of the braking device for vehicles. It is a figure which shows the discharge characteristic of the capacitor at the time of the electric power supply to the brake device for vehicles. It is a figure which shows the hydraulic system of a brake-by-wire system. 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 flowchart which shows the operation control of a backup power supply unit.

  EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated based on an Example.

First, the vehicle will be described.
As shown in FIG. 1, the vehicle according to the present embodiment is configured to be capable of braking the vehicle by a vehicle power source 1, a backup power source unit 2 (auxiliary power unit), and a brake-by-wire system 3 (electric brake means). A device 4 and a vehicle-side load 5 such as an air conditioner or an electronic device are provided. This vehicle is, for example, a hybrid vehicle including an internal combustion engine 6 (engine) and an electric motor 7 as a travel drive source, and regenerative braking that brakes the vehicle by regenerating kinetic energy of the vehicle into electric energy, Brake regenerative cooperative control that generates necessary braking force in combination with hydraulic braking by the by-wire system 3 is configured to be executable.

  In order to make the vehicle ready to run, the vehicle is provided with an ignition switch 8 (IG-SW) operated by an occupant, and an IG-SW sensor 8a for detecting the state of the ignition switch 8 is provided. When the internal combustion engine 6 is started by the operation of the ignition switch 8 and the vehicle can run, the ignition switch 8 is in the on state. The electric motor 7 can also be used as a starter for the internal combustion engine 6, but may be provided with a separate starter.

Next, the vehicle power source 1 will be described.
The vehicle power source 1 includes, for example, a 12V vehicle battery 11 (main power source), an alternator 12 connected in parallel to the battery 11 and capable of generating power by driving the internal combustion engine 6, and the like. The charging / discharging sensor 13 which can detect the charging / discharging state of is provided. The vehicle power supply 1 includes a brake-by-wire system using two lines, a first line L1 having a backup power supply unit 2 interposed in the middle thereof and a second line L2 disposed in parallel with the first line L1. 3 is connected to be able to supply power. The third line L3 branched from the middle part of the second line L2 is connected to the vehicle-side load 5.

Next, the backup power supply unit 2 will be described.
The backup power supply unit 2 is an auxiliary power supply dedicated to the brake-by-wire system 3 that supplies backup power to the brake-by-wire system 3 when there is a possibility that the power supply of the battery 11 to the brake-by-wire system 3 may be hindered. . The backup power supply unit 2 includes, for example, a first capacitor 21a and a second capacitor 21b as a plurality of power storage means, and includes a charging circuit unit 22, a first control unit 23 (control unit), and the like.

  The first capacitor 21a and the second capacitor 21b are each configured by a capacitor cell group in which a plurality of electric double layer capacitor cells are connected in series and parallel so that the voltage when fully charged is 12V, for example. The first capacitor 21a includes a first voltage sensor 26a that detects the voltage, and the second capacitor 21b includes a second voltage sensor 26b that detects the voltage. The backup power supply unit 2 may include three or more capacitors, but the plurality of capacitors preferably have the same specifications such as capacitance.

  The first and second capacitors 21a and 21b are connected to the charging circuit unit 22 so that they can be charged. The first capacitor 21a is connected to the first line L1 via a first contact 24a that can be electrically switched on and off so that power can be supplied, and the second capacitor 21b is connected via a second contact 24b. Connected to the first line L1. Furthermore, the first capacitor 21a and the second capacitor 21b can be connected in series via a third contact 24c that can be electrically switched on and off. Accordingly, the first contact form in which the third capacitor 24a is turned off and the first capacitor 21a or the second capacitor 21b is used alone, and the first capacitor 21a and the second capacitor 21b are connected in series by turning on the third contact 24c. The second connection form used can be switched.

  In the first line L1, a fourth contact 25 that can electrically switch on and off the connection between the battery 11 and the brake-by-wire system 3 is installed. The charging circuit unit 22 is connected to the first line L1 on the vehicle power source 1 side from the fourth contact 25, and the first circuit 21 is based on the control signal of the first control unit 23 when the first capacitor 21a is not supplying power. The capacitor 21a is charged, and the second capacitor 21b is charged in the same manner. The first control unit 23 turns off the first contact 24 a, the second contact 24 b, and the fourth contact 25 when not charging / discharging the power storage means of the backup power supply unit 2.

  As shown in FIG. 2, the first controller 23 is based on detection signals from the charge / discharge sensor 13, the first voltage sensor 26a, the second voltage sensor 26b, the brake pedal stroke sensor 47, and the IG-SW sensor 8a. The control signal is transmitted to the first contact 24 a to the fourth contact 25 and the charging circuit unit 22, and the control signal is transmitted to the second control unit 37 that controls the brake-by-wire system 3. In addition, the second control unit 37 transmits a control signal related to a target braking force, which will be described later, necessary for calculating the power supplied from the backup power supply unit 2 to the first control unit 23.

  The first control unit 23 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 for controlling charging / discharging are stored in the ROM, and a processing area used when the CPU performs a series of processing is provided in the RAM. The first control unit 23 operates by receiving power supply from the vehicle power source 1 through a power line (not shown).

The first control unit 23 operates on the brake-by-wire system 3 based on the target deceleration D corresponding to the target braking force input from the second control unit 37 and the deceleration D0 that can be generated by the occupant's pedaling force. Is calculated as shown in 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 exerted by the occupant, and the calculated required deceleration D1 is converted into a braking target torque, and the brake-by-wire system 3 is calculated based on the braking target torque. The first power E1 (required power) necessary for the operation of is calculated.

  Further, the first control unit 23 calculates the second electric power E <b> 2 as electric power that can be supplied from the battery 11 to the brake-by-wire system 3 based on the charging rate of the battery 11. And when the 1st electric power E1 is larger than the 2nd electric power E2, electric power is supplied to the brake-by-wire system 3 from the backup power supply unit 2. FIG.

  When the backup power supply unit 2 supplies power together with the vehicle power supply 1, the first control unit 23 supplies the difference power ΔE between the first power E1 and the second power E2 from the backup power supply unit 2. As shown in FIG. 1, for example, the first control unit 23 turns on the first contact 24 a and supplies the differential power ΔE from the first capacitor 21 a of the backup power supply unit 2. The first power E1 can be supplied from the backup power supply unit 2 instead of the vehicle power supply 1.

  When the first control unit 23 supplies electric power from the backup power supply unit 2, the backup power source increases as the depression stroke (hereinafter referred to as stroke) St of the brake pedal 41 by the occupant detected by the brake pedal stroke sensor 47 increases. The power supply time of the unit 2 is lengthened.

  As shown in FIG. 3, the discharge characteristics of the first and second capacitors 21a and 21b at the time of power supply include a boosting stage that outputs, for example, 50A as a peak current for boosting the brake fluid pressure for 200 msec, and a brake fluid pressure. For example, it is composed of a sustain stage that outputs 2 A for 12 seconds as a steady current to be held. The duration T of the maintenance stage is set to be proportional to the stroke St.

Next, the brake-by-wire system 3 will be described.
As shown in FIG. 1, the brake-by-wire system 3 can electrically open and close a power supply control circuit unit 31 to which power is supplied from the first and second lines L1 and L2, a motor 32, and a brake fluid flow path. And electromagnetic valves 33 to 36, a second control unit 37, and the like.

  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 second control unit 37 based on predetermined control conditions. Specifically, the power supplied from the first and second lines L1 and L2 is converted into a voltage or the like as necessary to be necessary for the motor driver 32a, the solenoid valve drivers 33a to 36a, and the second control unit 37. Distributing power. The second control unit 37 operates even under a situation where power is supplied from the vehicle power source 1 through a power line (not shown) and power supplied to the brake-by-wire system 3 is insufficient.

Here, a schematic configuration related to the operation system of the brake-by-wire system 3 will be described.
As shown in FIG. 4, the brake-by-wire system 3 includes a master cylinder 42 that can generate brake fluid pressure corresponding to the stroke St of the brake pedal 41 by an occupant's operation, a motor 32, and a pump unit that is driven by the motor 32. The electric brake booster 43, the reaction force generating mechanism 44, and the brake fluid pressure generated by the master cylinder 42 and / or the electric brake booster 43 are used to rotate the front, rear, left and right wheels FL, FR, RL, RR. Wheel cylinders 45a to 45d for braking, a second 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.

  The electric brake booster 43 is communicated with the wheel cylinders 45a and 45b via an electromagnetic valve 34 whose pump part can be opened and closed, and is communicated with the wheel cylinders 45c and 45d via an electromagnetic valve 35 which can be opened and closed. 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. As a result, when the occupant depresses or returns the brake pedal 41, a reaction force having a preset characteristic can be applied to the occupant via the brake pedal 41.

  The second control unit 37 can execute the deceleration control process and the pedal force control process by controlling the electric brake booster 43, the reaction force generation mechanism 44, the brake pedal stroke sensor 47, and the electromagnetic valves 33 to 36. It is configured.

As shown in FIG. 5, the second control unit 37 has a pedaling force characteristic map M1. The pedal effort characteristic map M1 is defined by a predetermined function, for example, a logarithmic function. As shown in the following formula (2), the sensation intensity of the occupant is proportional to the logarithm of the stimulation intensity.
A = klogB + K (2)
A is a sensory quantity, B is a physical quantity, k is a gain, and K is an integral constant.

  Based on the stroke St detected by the brake pedal stroke sensor 47 and the pedaling force characteristic map M1, the second control unit 37 sets a pedaling force F corresponding to the target operation reaction force, and generates an operation command signal corresponding to the pedaling force F. It is output to the mechanism 44.

  As shown in FIG. 6, the second control unit 37 has a braking characteristic map M2. The second 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 outputs an operation command signal corresponding to the target deceleration D. It is output to the motor driver 32a and the solenoid valve drivers 33a to 36a. Thereby, each wheel cylinder 45a-45d is driven and the braking of the target deceleration D based on the braking characteristic map M2 is performed. At the same time, the second control unit 37 sends control signals regarding the stroke St and the target deceleration D to the first control unit so that the brake-by-wire system 3 is supplied with electric power necessary for the operation of the brake-by-wire system 3. 23 is output.

  The first control unit 23 that has received the control signal output by the second control unit 37 calculates the power that the battery 11 can supply in order to supply the power necessary for the operation of the brake-by-wire system 3, and supplies the battery 11. When the power is insufficient, power is supplied from the backup power supply unit 2. The control of the backup power supply unit 2 by the first control unit 23 will be described based on the flowchart of FIG. Si (i = 1, 2,...) In the figure represents each step.

  First, in S1, information on the charge / discharge state of the battery 11 and the voltages of the first and second capacitors 21a, 21b of the backup power supply unit 2 is acquired, and the process proceeds to S2. In S2, it is determined whether or not the brake pedal 41 has been depressed. This determination is made based on the detection signal of the brake pedal stroke sensor 47, but can also be made based on the detection signal of a brake sensor (not shown) that detects whether the brake pedal 41 is depressed. If the determination is Yes, the process proceeds to S3, and if the determination is No, the process proceeds to S16.

  Next, in S3, it is determined whether or not an operation for turning on the ignition switch 8 is performed based on the output signal of the IG-SW sensor 8a. Since electric power for starting the internal combustion engine 6 is supplied from the battery 11 by this operation, the electric power supply capability of the battery 11 is in a state where there is no margin when this operation is being performed. If the determination is Yes, the process proceeds to S4, and if the determination is No, the process proceeds to S5.

  Next, in S4, the third contact 24c is turned on, the backup power supply unit 2 is switched to the second connection configuration in which the first and second capacitors 21a, 21b are connected in series, and the process proceeds to S7.

  On the other hand, if the determination in S3 is No, in S5, the target deceleration D is calculated based on the stroke St of the brake pedal 41, the pedal effort characteristic map M1, and the braking characteristic map M2, and the process proceeds to S6. In S6, the required deceleration D1 required for the vehicle is calculated using the calculated target deceleration D and the deceleration D0 that can be generated by the occupant's pedaling force, and the process proceeds to S7.

  Next, in S7, the 1st electric power E1 required for the action | operation of the brake-by-wire system 3 is calculated, and it progresses to S8. At this time, when the determination of S3 is Yes, a predetermined value set in advance is set as the first power E1, and when the determination of S3 is No, the first power E1 is calculated using the requested deceleration D1 calculated at S6. To do. If the determination in S3 is Yes, the first power E1 may be calculated based on the detection signal of the brake pedal stroke sensor 47. In S8, the second power E2 that can be supplied from the battery 11 to the brake-by-wire system 3 is calculated based on the charge / discharge state of the battery 11 detected in S1, and the process proceeds to S9.

  Next, in S9, it is determined whether or not the first power E1 is greater than the second power E2. If the determination in S9 is Yes, that is, if the battery 11 cannot supply the first power E1, the process proceeds to S10, and it is determined in S10 whether the backup power supply unit 2 is in the first connection configuration. If the determination in S10 is Yes, the process proceeds to S11, and if the determination in S10 is No, the process proceeds to S13.

  Next, in S11, it is determined whether or not each capacitor voltage is less than the reference voltage. The reference voltage is set higher than the operating voltage of the brake-by-wire system 3 in advance so that the voltage does not become lower than the operating voltage during the power supply of the capacitor in the first connection form. For example, when the operating voltage is set to 6V to 16V and the capacitor is supplied with power once in the first connection configuration, and the voltage drops by 2V, the reference voltage is set to 8V.

  If the determination in S11 is Yes, the process proceeds to S12. In S12, the third contact 24c is turned on, the backup power supply unit 2 is switched to the second connection form, and the process proceeds to S13. In step S13, the first contact 24a is turned on, power is supplied from the backup power supply unit 2 having the second connection configuration to the brake-by-wire system 3, and the process returns. Since the first and second capacitors 21a and 21b are switched to the second connection configuration in which the first and second capacitors 21a and 21b are connected in series, the output voltage of the backup power supply unit 2 is increased so that the operating voltage of the brake-by-wire system 3 can be output. The brake-by-wire system 3 drives the electric brake booster 43 with the electric power supplied from the battery 11 and the backup power supply unit 2 and exhibits a braking force corresponding to the required deceleration D1.

  If the determination in S11 is No, the process proceeds to S14. In S14, power is supplied from the capacitor having the highest voltage in the first connection form to the brake-by-wire system 3, and the process returns. At this time, when power is supplied from the first capacitor 21a, the first contact 24a is turned on, and when power is supplied from the second capacitor 21b, the second contact 24b is turned on. The brake-by-wire system 3 drives the electric brake booster 43 with the electric power supplied from the battery 11 and the backup power supply unit 2 and exhibits a braking force corresponding to the required deceleration D1.

  If the determination in S9 is No, the battery 11 can supply the first power E1, so the process proceeds to S15 to supply power from the battery 11 and return. The brake-by-wire system 3 drives the electric brake booster 43 with the electric power supplied from the battery 11 and exhibits a braking force corresponding to the required deceleration D1.

  On the other hand, if the determination in S2 is No, that is, if there is no occupant braking operation and no electric power is supplied to the electric brake booster 43 of the brake-by-wire system 3, it is determined in S16 whether the backup power supply unit 2 is in the second connection configuration. To do. If the determination in S16 is Yes, the process proceeds to S17. In S17, the third contact 24c is turned off to switch to the first connection form, and the process proceeds to S18. If the determination in S16 is No, the process proceeds to S18.

  Next, in S18, it is determined whether or not the ignition switch 8 is on. Since the vehicle does not travel unless the ignition switch 8 is on, the first and second capacitors 21a and 21b are not charged. If the determination in S18 is Yes, the process proceeds to S19, and if the determination is No, the process returns.

  Next, in S19, it is determined whether or not the first and second capacitors 21a and 21b can be charged. This determination is performed based on the charge / discharge state of the battery 11 acquired in S1 and the voltages of the first and second capacitors 21a and 21b. If the battery 11 can supply power for charging and if at least one capacitor is not fully charged, the battery 11 can be charged. Therefore, the determination in S19 is Yes, and the process proceeds to S20, where the charging circuit unit 22 charges the capacitor. Return. If the determination in S19 is No, the process returns without charging the capacitor.

Next, functions and effects of the vehicle braking device 4 according to this embodiment will be described.
The vehicular braking device 4 supplies power from the backup power supply unit 2 of the first connection configuration when the power supplied from the battery 11 (main power supply) to the brake-by-wire system 3 (electric brake means) is insufficient. The optimum braking force is obtained by operating the brake-by-wire system 3. When the predetermined condition is satisfied, when the internal combustion engine 6 (engine) is started, or when both the first and second capacitors 21a and 21b are less than the reference voltage, the backup power supply unit 2 is switched from the first connection configuration to the first. Switch to 2 connection mode.

  Therefore, even when the power supply of the battery 11 is insufficient, even if any of the first and second capacitors 21a and 21b alone impedes the power supply to the brake-by-wire system 3, the first and second capacitors 21a, The voltage can be raised by switching to the second connection form in which 21b is connected in series, so that power can be supplied from the backup power supply unit 2 to the brake-by-wire system 3.

  In addition, the overall storage capacity of the first and second capacitors 21a and 21b in the second connection form is smaller than the overall storage capacity of the first and second capacitors 21a and 21b in the first connection form. By switching to the first connection form and charging when there is no brake operation by the occupant, the amount of power stored in the backup power supply unit 2 can be maximized in preparation for the next power supply.

Next, a modified example in which the embodiment is partially changed will be described.
1] In the above embodiment, an example of a hybrid vehicle capable of executing regenerative braking and hydraulic braking has been described. However, the present invention is applicable to an electric vehicle equipped with a brake-by-wire system 3, a vehicle equipped with only an internal combustion engine 6, and the like. is there.

2] In the above-described embodiment, the example in which the target deceleration D is set based on the stroke St of the brake pedal 41 operated by the occupant has been described with emphasis on the occupant's request. The deceleration required for avoiding the danger of the vehicle may be set as the target deceleration D regardless of the operation amount of the brake pedal 41. Specifically, for example, a camera, a radar, or the like is provided as a situation detection unit capable of detecting the situation ahead of the traveling direction, and the target is based on the detection result of the situation detection unit on the condition that the driver depresses the brake pedal 41. Set the deceleration D. In this case, it is preferable to set the set target deceleration D to the requested deceleration D1.

3] For example, when the first capacitor 21a supplies the first power E1 instead of the battery 11, the battery 11 can output the power for charging the second capacitor 21b not supplied with power. It is also possible to charge the capacitor 21b. In this case, power can be stored in the backup power supply unit 2 in preparation for the next power supply opportunity, and switching to the second connection configuration can be suppressed.

  In addition, those skilled in the art can implement the present invention with various modifications added without departing from the spirit of the present invention, and the present invention includes such modifications.

1: Vehicle power supply 2: Backup power supply unit 3: Brake-by-wire system (electric brake means)
4: Vehicle braking device 8: Ignition switch (IG-SW)
8a: IG-SW sensor 11: Battery (main power supply)
13: charge / discharge sensor 21a: first capacitor (power storage means)
21b: 2nd capacitor (electric storage means)
22: charging circuit unit 23: first control unit (control means)
24a: 1st contact 24b: 2nd contact 24c: 3rd contact 26a: 1st voltage sensor 26b: 2nd voltage sensor 37: 2nd control part 41: Brake pedal 43: Electric brake booster 47: Brake pedal stroke sensor L1: First line

Claims (3)

Electric brake means capable of braking a vehicle by driving a motor by a passenger's brake operation, a main power source capable of supplying electric power to the electric brake means, and a plurality of power storage means capable of supplying electric power to the electric brake means When the required power of the auxiliary power supply device and the electric brake means is larger than the power that can be supplied by the main power supply, one of the plurality of power storage means is used together with the main power supply or instead of the main power supply. In a vehicle braking device, comprising: a control means for supplying electric power from the auxiliary power supply device to the electric brake means in a first connection form to be used;
The control means switches the auxiliary power supply device from the first connection form to the second connection form in which the plurality of power storage means are connected in series when the engine is started . Braking device. Electric brake means capable of braking a vehicle by driving a motor by a passenger's brake operation, a main power source capable of supplying electric power to the electric brake means, and a plurality of power storage means capable of supplying electric power to the electric brake means When the required power of the auxiliary power supply device and the electric brake means is larger than the power that can be supplied by the main power supply, one of the plurality of power storage means is used together with the main power supply or instead of the main power supply. In a vehicle braking device, comprising: a control means for supplying electric power from the auxiliary power supply device to the electric brake means in a first connection form to be used;
The control unit connects the plurality of power storage units in series from the first connection configuration when the voltages of the plurality of power storage units are all less than a preset reference voltage. The vehicle brake device is switched to the second connection form used. Each of the plurality of power storage means is a capacitor,
3. The vehicle according to claim 1, wherein the control unit switches the second connection form to the first connection form to charge the capacitor when there is no brake operation by the occupant. Braking device.

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