JP2012030733A - Electronically controlled brake power source system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronically controlled brake power source system which employs an inexpensive constitution not requiring a back-up power source, and nonetheless diagnoses battery deterioration when a battery is deteriorated.SOLUTION: The electronically controlled brake power source system includes: a vehicle power source 1; a plurality of load units 2, 3, 4; an electric booster 2; and a battery deterioration diagnosis circuit 10. The vehicle power source 1 has a DC/DC converter 11 and a battery 12 and generates a battery voltage VB. The plurality of load units 2, 3, 4 are connected in parallel with the vehicle power source 1 via a power source line 5. The booster 2 is one of the plurality of load units 2, 3, 4 and the operable voltage value Vmin of the booster 2 is preset to a value smaller than operable voltage values VMIN of load units 3, 4. The battery deterioration diagnosis circuit 10 performs the battery deterioration diagnosis which monitors the deterioration in the battery voltage VB of the vehicle power source 1 while the electric booster 2 is operated.

Description

  The present invention relates to an electronically controlled brake power supply system in which a plurality of load units including an electronically controlled brake are connected in parallel to a vehicle power supply via a power supply line.

  Conventionally, as an electronically controlled brake power supply system in which a plurality of load units including an electronically controlled brake are connected to a vehicle power supply in parallel via a power supply line, a system having a backup power supply separately from the vehicle power supply is known. . This backup power supply includes a first capacitor, a second capacitor, and a switching unit capable of switching both capacitors to a parallel connection or a series connection (see, for example, Patent Document 1).

JP 2004-338777 A

  However, in the conventional electronically controlled brake power supply system, the operable voltage values of a plurality of load units including the electronically controlled brake are set to the same voltage value (for example, in the case of a 12V electric load, the operable voltage of the load The value is unified to 9V). Therefore, if the battery has deteriorated and the main power supply (eg, DC / DC converter, alternator, etc.) fails, the battery voltage will drop, but the battery voltage will be lower than the operable voltage value of the load unit. If it falls, the operation of the electronically controlled brake cannot be secured. For this reason, a backup power supply is indispensable for the battery deterioration diagnosis, such as performing the battery deterioration diagnosis while ensuring the operation of the electronically controlled brake using the backup power supply, thereby increasing the system cost. There was a problem.

  The present invention has been made paying attention to the above problems, and provides an electronically controlled brake power supply system that can perform a battery deterioration diagnosis while having a low-cost configuration that does not require a backup power supply when the battery has deteriorated. The purpose is to do.

In order to achieve the above object, the electronically controlled brake power supply system of the present invention is a means including a vehicle power supply, a plurality of load units, an electronically controlled brake, and a battery deterioration diagnosis means.
The vehicle power source includes a main power source and a battery, and generates a battery voltage.
The plurality of load units are connected in parallel to the vehicle power supply via a power supply line.
The electronic control brake is one of the plurality of load units, and the operable voltage value is set to a value smaller than the operable voltage values of the other load units.
The battery deterioration diagnosis means performs a battery deterioration diagnosis for monitoring a decrease in battery voltage of the vehicle power supply in an operating state of the electronic control brake.

As described above, the electronically controlled brake sets the operable voltage value to a value smaller than the operable voltage values of the other load units. For this reason, if the battery has deteriorated and the main power supply fails, the battery voltage will drop, but even if the battery voltage drops below the operable voltage value of the load unit excluding the electronic control brake, the electronic control brake The operation of the electronically controlled brake is ensured as long as it does not fall below the operable voltage value.
In other words, the operation of the electronic control brake can be ensured without using a backup power source in the battery deterioration diagnosis performed by monitoring the decrease in the battery voltage in the operation state of the electronic control brake.
As a result, when the battery is deteriorated, the battery deterioration diagnosis can be performed with an inexpensive configuration that does not require a backup power source.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram showing an electronically controlled brake power supply system according to a first embodiment mounted on an electric vehicle. It is a circuit diagram which shows the electric booster which has the inverter circuit by a basic composition in the electronically controlled brake power supply system of Example 1. FIG. It is a flowchart which shows the flow of the battery deterioration diagnostic process performed in the battery deterioration diagnostic circuit of the electronically controlled brake power supply system of Example 1. FIG. 6 is a time chart showing battery voltage characteristics when a failure occurs in the main power supply (DC / DC converter) when the battery is deteriorated in the electronically controlled brake power supply system of the first embodiment.

  Hereinafter, the best mode for realizing an electronically controlled brake power supply system of the present invention will be described based on Example 1 shown in the drawings.

First, the configuration will be described.
FIG. 1 is an overall system diagram showing an electronically controlled brake power supply system according to a first embodiment mounted on an electric vehicle. The overall system configuration will be described below with reference to FIG.

  As shown in FIG. 1, the electronically controlled brake power supply system of Embodiment 1 includes a vehicle power supply 1, an electric booster 2 (electronically controlled brake, load unit), an electric hydraulic circuit 3 (load unit), and a general load 4 ( Load unit) and a battery deterioration diagnosis circuit 10 (battery deterioration diagnosis means).

  The electronically controlled brake power supply system is mounted on electric vehicles such as electric vehicles, hybrid vehicles, and fuel cell vehicles. In the case of an electric vehicle, regenerative cooperative control is performed to obtain the driver's required braking force with the hydraulic braking force and the regenerative braking force. For this reason, it is highly necessary to use the electric booster 2 capable of performing boost control with a high degree of freedom, compared to an engine vehicle that obtains the driver's required braking force by hydraulic braking force. As a brake system using the electric booster 2 Yes.

  The vehicle power source 1 includes a DC / DC converter 11 (main power source) and a battery 12, and generates a battery voltage (battery voltage value VB is, for example, VB = 12V). The electric booster 2, the electrohydraulic circuit 3, and the general load 4 are connected in parallel as a plurality of load units with a 12 V electric load downstream of the vehicle power source 1. Here, the general load 4 is used as a general term for a plurality of load units such as a 12V electric load other than the electric booster 2 and the electrohydraulic circuit 3, for example, an air conditioner, an audio device, and a power window.

  The electric booster 2 is provided in a brake fluid pressure generating device 6 including a brake pedal and a master cylinder, and the assist motor operable voltage value Vmin (for example, Vmin = 7 V) is set to the other load unit operable voltage value VMIN. A value smaller than (for example, VMIN = 9V) is set. The electric booster 2 assists the pedaling force by the driver with a motor torque instead of a general negative pressure booster during braking operation. The electric booster 2 is assisted by a controller 21, an interruption relay 22, an inverter circuit 23, 3 And a phase motor 24.

  The controller 21 calculates an input from the driver and sends a command to the inverter circuit 23. The three-phase motor 24 is controlled according to the command, and the driver input is assisted with a necessary amount of boost. In addition to this boost control, a short-circuit diagnosis is performed in which an excessive current flows through the inverter circuit 23. When a short-circuit diagnosis is made, the energization to the inverter circuit 23 is interrupted by a command to the cut-off relay 22.

The electrohydraulic circuit 3 is an ABS actuator used for ABS / TCS / VDC control, and an oil pump motor 31 capable of self-increasing the brake fluid pressure and a plurality of valve solenoids capable of adjusting the brake fluid pressure of each wheel of the vehicle. 32, 33,...
Here, ABS / TCS / VDC control means that the vehicle attitude control function (VDC function), TCS function and ABS function are realized by the ABS / TCS / VDC unit to improve driving safety and support the driver. Control.

  The ABS / TCS / VDC unit includes an electrohydraulic circuit 3, an ABS / TCS / VDC controller 7, various sensors 8, and an engine controller 9. The ABS / TCS / VDC controller 7 detects the driver's driving operation and vehicle speed using various sensors 8, and automatically generates brake pressure (command to the electrohydraulic circuit 3) and engine output (command to the engine controller 9). Control. In addition, the slippery road surface, cornering, and side skid that occur when avoiding obstacles are reduced, and driving safety is improved. Bidirectional communication is established between the ABS / TCS / VDC controller 7 and the controller 21 by local communication or CAN communication.

  The battery deterioration diagnosis circuit 10 performs a battery deterioration diagnosis for monitoring a decrease in the battery voltage of the vehicle power supply 1 while the electric booster 2 is operated. That is, when the ignition switch 13 before the operation of the electrohydraulic circuit 3 or the general load 4 is turned off to on, the electric booster 2 is forcibly operated, and the battery voltage value VB of the vehicle power source 1 in the forcible operation state is measured. . When the battery voltage value VB becomes equal to or lower than the operable voltage value Vmin of the electric booster 2, the battery is diagnosed as being deteriorated, and the driver is notified by the operation of the notification device 14 that the brake boosting function is reduced. To do. As a notification method by the notification device 14, one of a method for appealing to sight by lighting a notification lamp, a method for appealing to hearing by a notification buzzer sound, a method for appealing to tactile sensation by notification vibration or the like, or a plurality of methods This is done in combination.

  FIG. 2 is a circuit diagram showing an electric booster having an inverter circuit having a basic configuration in the electronically controlled brake power supply system of the first embodiment. Hereinafter, based on FIG. 2, the structure of the electric booster 2 is demonstrated.

  As shown in FIG. 2, the electric booster 2 includes a controller 21, a cutoff relay 22, an inverter circuit 23, and a three-phase motor 24.

  The cutoff relay 22 is a relay for cutting off the vehicle power supply 1 when the system is not operating or when an abnormality occurs and the system is stopped. Usually, it is commanded from the controller 21 in the electric booster 2.

The inverter circuit 23 includes a shunt resistor 23a and six changeover switches 23b, 23c, 23d, 23e, 23f, and 23g.
The shunt resistor 23a is a highly accurate resistor having a small resistance value for monitoring the current flowing from the power supply line 5. Actually, the flowing current is taken into the monitor circuit of the controller 21 as a potential difference.
The changeover switch 23b uses a power FET, and sequentially controls the upstream changeover switches 23b, 23c, 23d and the downstream changeover switches 23e, 23f, 23g to control the current flowing to each phase (coil). is doing.

  The three-phase motor 24 is driven to rotate by switching each phase by high-speed switching by PWM from the inverter circuit 23. However, not only the three-phase motor 24 but also a DC brush motor or the like, the rotational drive control can be performed even if a mechanical relay or the like is used instead of the inverter circuit 23 with an H-bridge motor driver.

  FIG. 3 is a flowchart illustrating the flow of the battery deterioration diagnosis process executed by the battery deterioration diagnosis circuit 10 of the electronically controlled brake power supply system according to the first embodiment. Hereinafter, each step of FIG. 3 will be described.

  In step S1, it is determined whether or not the switch signal from the ignition switch 13 is ON. If YES (IGN-SW is OFF → ON), the process proceeds to step S2. If NO (IGN-SW is OFF), the determination in step S1 is repeated.

  In step S2, following the determination that the ignition switch 13 has been turned from OFF to ON in step S1, the shut-off relay 22 is turned ON for the controller 21 of the electric booster 2, and the three-phase motor 24 is turned on even without a brake operation. A command to forcibly drive is output, and the process proceeds to step S3.

  In step S3, following the forcible operation of the electric booster 2 in step S2, the battery voltage is measured when a predetermined time for determining battery deterioration has elapsed from the start of the forcible operation, and the battery voltage value VB obtained by the measurement is read. Proceed to

  In step S4, following the reading of the battery voltage value VB in step S3, it is determined whether or not the measured battery voltage value VB is less than or equal to the operable voltage value Vmin of the electric booster 2. If YES (VB ≦ Vmin: diagnosis that there is battery deterioration), the process proceeds to step S5. If NO (VB> Vmin: diagnosis that there is no battery deterioration), the process proceeds to step S6.

  In step S5, following the diagnosis that the battery has deteriorated in step S4, a notification command is output to the notification device 14, and the process proceeds to step S6.

  In step S6, following the diagnosis of no battery deterioration in step S4 or the output of the notification command in step S5, a command to stop the three-phase motor 24 is output to the controller 21 of the electric booster 2, and the end Proceed to

Next, the operation will be described.
First, “the problem of an electric vehicle equipped with an electronically controlled brake” will be described. Next, the operation of the electronically controlled brake power supply system according to the first embodiment will be described by dividing it into “reason for performing battery deterioration diagnosis without using a backup power supply” and “battery deterioration diagnosis operation”.

[Issues with electric vehicles equipped with electronically controlled brakes]
In an electric vehicle equipped with an electronically controlled brake (electric booster, etc.) that uses electric energy, if the 12V battery has deteriorated and the main power source (DC / DC converter, alternator, etc.) fails, the brake booster It is impossible to notify the driver of the decline before driving.

That is, a gasoline vehicle or the like can inform the driver of the deterioration of the 12V battery depending on whether or not the engine has been started by driving the starter motor when the engine is started.
On the other hand, in an electric vehicle such as an electric vehicle or a hybrid vehicle, the starter motor is not driven at the start of travel, and travel is possible.

  For this reason, in an electric vehicle having an electronically controlled brake, when the battery is running in a deteriorated state and the main power supply fails, the battery voltage decreases due to the operation of the 12V electric load.

  Therefore, as described in Patent Document 1 above, a configuration having another dedicated power source (backup power source) to compensate for the reduction in the boosting function due to the electronically controlled brake when the battery voltage has dropped. Is generally. Further, before running when the battery is deteriorated, even if the battery voltage is lowered, the operation of the electronic control brake can be ensured by the backup power source, so that the battery deterioration diagnosis can be performed. It is also possible to notify the driver in advance that the boosting function will be reduced due to the failure of the main power supply.

  However, when the battery deterioration diagnosis is performed, the backup power supply is indispensable, which increases the system cost. In other words, in an electric vehicle with an electronically controlled brake, if the battery has deteriorated, there is a demand for a configuration that can notify the driver in advance that the boost will drop due to the failure of the main power supply without using a backup power supply. There is.

[Reason for battery deterioration diagnosis without using backup power supply]
Hereinafter, the reason why the battery deterioration diagnosis can be performed without using the backup power supply in the electronically controlled brake power supply system according to the first embodiment will be described with reference to FIG. Note that “e-ACT” described in FIG. 4 represents the electric booster 2.

  The example of FIG. 4 is a time chart showing battery voltage characteristics when a failure occurs in the DC / DC converter 11 as the main power source when the battery 12 is deteriorated. When the operable voltage value of the electric booster 2 is 7V, the operable voltage value of the other load units is 9V, and the DC / DC converter 11 fails during the operation of a plurality of load units including the electric booster 2. Show.

  When a failure occurs in the DC / DC converter 11 that is the main power source at time t1, the battery voltage has a slope corresponding to the electrical load (= load level) of the plurality of load units operating at that time from time t1. Decreases from 12V. Then, when the battery voltage drops to 9V at time t2, since the operable voltage value of the general 12V auxiliary machine (load unit) is less than 9V thereafter, the general 12V auxiliary machine except the electric booster 2 has the operating limit. To stop. That is, when the battery voltage decreases to 9V, the electric load is cut off naturally as the battery voltage decreases, so no special shut-off mechanism is required.

  Since there are many 12V electric loads that cannot be operated from time t2 when the battery voltage drops to 9V to time t3 when the battery voltage reaches 7V, which is the operation limit of the electric booster 2, the load The level decreases, and the battery voltage decrease gradient becomes gentler than the gradient from time t1 to time t2. That is, in the region from time t2 to time t3, the electric load is at a load level of about (e-ACT + α).

  As described above, when the battery 12 is deteriorated, if the DC / DC converter 11 breaks down, the battery voltage decreases. However, even if the battery voltage falls below the operable voltage value (9V) of the load unit excluding the electric booster 2, as long as it does not fall below the operable voltage value (7V) of the electric booster 2, in the region from time t2 to time t3 The operation of the electric booster 2 is ensured. In addition, in the region from time t2 to time t3, the battery voltage decreases gradually.

  Therefore, the battery voltage in the region from time t2 to time t3 from the vehicle power source 1 can be used for battery deterioration diagnosis as a dedicated power source when backing up the operation of the electric booster 2, and the battery deterioration diagnosis It can be realized without having an electric load blocking mechanism.

  As described above, the operation of the electric booster 2 can be ensured without using a backup power source at the time of battery deterioration diagnosis performed by monitoring the decrease in the battery voltage in the operating state of the electric booster 2. Then, in the travel preparation stage before the DC / DC converter 11 is operated, current is passed through the three-phase motor 24 in the electric booster 2 and the amount of decrease in the battery voltage VB is measured, thereby diagnosing deterioration of the battery 12. be able to.

[Battery deterioration diagnosis]
As described above, when the battery 12 is deteriorated, a configuration in which the driver can be notified in advance that the boost is reduced when a failure occurs in the DC / DC converter 11 without using a backup power source. is necessary. Hereinafter, based on FIG. 3, the battery deterioration diagnosis function reflecting this will be described.

  First, when the battery 12 is not deteriorated, when the driver performs an ignition key input operation, in the flowchart of FIG. 3, the flow proceeds from step S1, step S2, step S3, step S4, step S6, and end. That is, when the battery 12 is not deteriorated, VB> Vmin is satisfied in step S4, so that the three-phase motor 24 that is forcibly operated in step S6 is stopped and the battery is performed immediately after the ignition input operation. End the deterioration diagnosis.

  Next, when the battery 12 is deteriorated and the driver performs an ignition key input operation, in the flowchart of FIG. 3, the process proceeds from step S1, step S2, step S3, step S4, step S5, step S6, and end. Flowing. That is, when the battery 12 is deteriorated, VB ≦ Vmin is satisfied in step S4, so that a notification command is output in step S5 to notify the driver that the battery 12 is deteriorated. By this notification, the driver can recognize that the brake boosting function is lowered before traveling. Then, the three-phase motor 24 forcibly operated in step S6 is stopped, and the battery deterioration diagnosis performed immediately after the ignition turning-on operation is finished.

Next, the effect will be described.
In the electronically controlled brake power supply system according to the first embodiment, the following effects can be obtained.

(1) A vehicle power source 1 having a main power source (DC / DC converter 11) and a battery 12 and generating a battery voltage VB;
A plurality of load units 2, 3, 4 connected in parallel with the vehicle power source 1 via a power line 5,
An electronically controlled brake (electric booster 2) which is one of the plurality of load units 2, 3 and 4 and whose operable voltage value Vmin is set to be smaller than the operable voltage value VMIN of the other load units 3 and 4; ,
A battery deterioration diagnosis means (battery deterioration diagnosis circuit 10, FIG. 3) for performing a battery deterioration diagnosis for monitoring a decrease in the battery voltage VB of the vehicle power supply 1 in an operating state of the electronic control brake (electric booster 2);
Equipped with.
For this reason, when the battery has deteriorated, the battery deterioration diagnosis can be performed with an inexpensive configuration that does not require a backup power source.

(2) The battery deterioration diagnosis means (battery deterioration diagnosis circuit 10) forcibly operates the electronic control brake (electric booster 2) before the other load units 3 and 4 start operation, Based on the battery voltage value VB of the vehicle power source 1, the battery deterioration diagnosis is performed (steps S1, S2, S3 in FIG. 3).
For this reason, in addition to the effect of (1), when the battery 12 is deteriorated, the failure of the main power source (DC / DC converter 11) causes the brake function (boost function) to decrease. The other load units 3 and 4 can be diagnosed before starting operation.

(3) The battery deterioration diagnosis means (battery deterioration diagnosis circuit 10) is configured such that the battery voltage value VB of the vehicle power source 1 when the electronic control brake (electric booster 2) is operated is the electronic control brake (electric booster). When the voltage becomes less than the operable voltage value Vmin of 2), it is diagnosed that the battery is deteriorated (step S4 in FIG. 3).
For this reason, in addition to the effect of (2), when diagnosing battery deterioration, it is possible to diagnose battery deterioration with high diagnostic accuracy by monitoring the limit to the operation of the electronically controlled brake (electric booster 2). it can.

(4) The electronically controlled brake is an electric booster 2 that controls a brake boost characteristic.
When the battery deterioration diagnosis means (battery deterioration diagnosis circuit 10) diagnoses the battery deterioration, it notifies the driver (step S5 in FIG. 3).
For this reason, in addition to the effects of (1) to (3), when the battery 12 is deteriorated, a malfunction occurs in the main power supply (DC / DC converter 11), and the boosting function is reduced. You can notify the driver.

  As mentioned above, although the electronically controlled brake power supply system of this invention has been demonstrated based on Example 1, it is not restricted to this Example 1 about a concrete structure, Invention which concerns on each claim of a claim Design changes and additions are permitted without departing from the gist of the present invention.

  In the first embodiment, an example in which the electric booster 2 that controls the brake boost characteristic is used as the electronically controlled brake is shown. However, the electronically controlled brake may be an electrohydraulic circuit 2 having a pump motor, and any load can be used as long as it is an electronically controlled brake provided in the middle of the brake system from the brake operation input unit to the wheel braking unit. It may be a unit.

  In the first embodiment, the battery deterioration diagnosis circuit 10 is provided independently. However, an example in which a battery deterioration diagnosis unit is incorporated in a brake system controller such as the controller 21 of the electric booster 2 or the VDC / TCS / ABS controller 7 may be used.

  In the first embodiment, an example of application to an electric vehicle such as a hybrid vehicle or an electric vehicle has been shown, but the present invention can also be applied to a general gasoline vehicle. When applied to an electric vehicle, the vehicle power supply configuration is “DC / DC converter + battery”. However, when applied to a general gasoline vehicle, the vehicle power source configuration is “alternator + battery”.

1 Vehicle power supply 11 DC / DC converter (main power supply)
12 Battery 2 Electric booster (Electronic brake, load unit)
21 Controller 22 Interrupting relay 23 Inverter circuit 24 Three-phase motor 3 Electric hydraulic circuit (load unit)
4 General load (load unit)
5 Power line 7 VDC / TCS / ABS controller 10 Battery deterioration diagnosis circuit (Battery deterioration diagnosis means)
13 Ignition switch 14 Notifier VB Battery voltage value VMIN Operable voltage value other than electric booster 2 Vmin Operable voltage value of electric booster 2

Claims (4)

A vehicle power source having a main power source and a battery and generating a battery voltage;
The vehicle power supply is a plurality of load units connected in parallel via a power line,
An electronically controlled brake that is one of the plurality of load units and has an operable voltage value set to a value smaller than the operable voltage value of another load unit;
Battery deterioration diagnosis means for performing a battery deterioration diagnosis for monitoring a decrease in battery voltage of the vehicle power supply in an operating state of the electronic control brake;
An electronically controlled brake power supply system characterized by comprising: In the electronically controlled brake power supply system according to claim 1,
The battery deterioration diagnosis means forcibly operates the electronic control brake before the other load unit starts operation, and performs battery deterioration diagnosis based on the battery voltage value of the vehicle power supply in the forced operation state. Electronically controlled brake power system characterized by In the electronically controlled brake power supply system according to claim 2,
The battery deterioration diagnosing means diagnoses the battery deterioration when the battery voltage value of the vehicle power source when the electronic control brake is operated is equal to or less than the operable voltage value of the electronic control brake. An electronically controlled brake power system. In the electronically controlled brake power supply system according to any one of claims 1 to 3,
The electronically controlled brake is an electric booster that controls a brake boost characteristic,
An electronically controlled brake power supply system characterized in that the battery deterioration diagnosis means notifies the driver when the battery deterioration diagnosis is made.