JP2007168515A - Electric brake system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniform the deterioration of a battery which is exclusively for an electric brake. <P>SOLUTION: A battery of a high charged state among a plurality of batteries is connected to an actuator of a high target braking force among a plurality of actuators. At the same time, a battery of a low charged state among the plurality of batteries is connected to an actuator of a low target braking force among the plurality of actuators. Also, a generator of a high generating voltage among a plurality of generators is connected to a battery of a low charged state among the plurality of batteries. At the same time, a generator of a low generating voltage among the plurality of generators is connected to a battery of a high charged state among the plurality of batteries. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electric brake device for a vehicle.

  The electric brake actuators for the wheels on the diagonal of the vehicle are used as one brake system, and dedicated batteries for the electric brakes are provided for each system, and a generator for charging these dedicated batteries is installed on the left and right rear wheels. There is known an electric brake device in which a braking force is secured by the other electric brake system even if an abnormality occurs in the electric brake system (see, for example, Patent Document 1).

Prior art documents related to the invention of this application include the following.
JP 2000-295703 A

  However, in the above-described conventional electric brake device, depending on the traveling environment of the vehicle, there is a difference between the discharge amount and the charge amount of the battery for each brake system, and the deterioration of a specific battery may progress.

(1) A battery having a high charge state among a plurality of batteries and an actuator having a high target braking force among a plurality of actuators are connected, and a battery having a low charge state and a plurality of actuators among the plurality of batteries are connected. Connect an actuator with a low target braking force.
(2) Further, a generator having a high generation voltage among the plurality of generators is connected to a battery having a low charge state among the plurality of batteries, and a generator having a low generation voltage within the plurality of generators Connect to a battery with a high charge state among multiple batteries.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that charge / discharge concentrates on the specific battery of several batteries, and deterioration progresses.

  FIG. 1 is a diagram showing a configuration of an embodiment. Electric brake actuators 5 to 8 are installed on the front and rear wheels 1 to 4 of the vehicle, respectively. Each of the electric brake actuators 5 to 8 includes an electric motor (not shown), and the control device 18 supplies electric power corresponding to the target brake force from the electric brake dedicated batteries 13 and 14 to the electric motor, and pushes the brake pad to the brake rotor. A braking force corresponding to the target braking force is generated for each wheel.

  The battery 11 supplies electric power to in-vehicle devices other than the electric brake actuators 5-8. The electric brake dedicated batteries 13 and 14 are dedicated batteries for supplying electric power only to the electric brake actuators 5 to 8. The generators 15 and 16 are installed on the left and right rear wheels 3 and 4 of the vehicle, and regenerate the traveling energy of the vehicle to charge the batteries 13 and 14 for the electric brake.

  The control device 18 controls the battery brake switching circuit 25 when discharging the electric brake dedicated batteries 13 and 14 from the electric brake actuators 13 and 14 to operate the electric brake actuators 5 to 8 to charge the state of charge SOC (charge) of the dedicated batteries 13 and 14. The higher one is connected to the one of the electric brake actuators 5 to 8 that has a large target brake force and requires large electric power. The battery brake switching circuit 25 may be switched using a relay, or may be switched using a semiconductor switch.

  When the regenerative electric power is supplied from the generators 15 and 16 to the electric brake dedicated batteries 13 and 14 to perform charging, the control device 20 controls the generator battery switching circuit 26 to generate electric power from the generators 15 and 16. A generator having a high voltage is connected to a dedicated battery having a low state of charge SOC among the dedicated batteries 13 and 14. The generator battery switching circuit 26 may be switched using a relay, or may be switched using a semiconductor switch.

  The battery charge state detection device 27 detects the charge state SOC of the electric brake dedicated batteries 13 and 14. As a method of detecting the state of charge SOC, the release voltage of the dedicated batteries 13 and 14 is measured with the electric brake dedicated batteries 13 and 14 electrically disconnected from the electric brake actuators 5 to 8 and the generators 15 and 16. There is a method for detecting the state of charge SOC based on the no-load release voltage.

  As another detection method, the charge current amount to the electric brake dedicated batteries 13 and 14 is measured, the charge current is integrated over time, the charge amount stored in the dedicated batteries 13 and 14 is calculated, and the charge state SOC is detected. can do. Furthermore, as another detection method, the charging current and the charging voltage flowing to the electric brake dedicated batteries 13 and 14 are utilized by utilizing the property that the charging current changes according to the state of charge SOC when the battery is charged with a constant voltage. Based on this, the state of charge SOC can also be detected.

  The voltage detection circuit 28 detects the generated voltage of the generators 15 and 16. The accelerator sensor 23 detects the amount of depression of the accelerator pedal, and the brake sensor 24 detects the amount of depression of the brake pedal.

  FIG. 2 is a flowchart illustrating a switching operation between the generator and the battery and a switching operation between the battery and the electric brake actuator according to the embodiment. In step 101, the battery charge state detection device 27 detects the charge state C1 (SOC) of the electric brake dedicated battery 13 and the charge state C2 (SOC) of the electric brake dedicated battery 14. In the following step 102, it is confirmed whether or not the accelerator pedal is in the released state (off) by the accelerator sensor 23. If the accelerator pedal is in the released state, the process proceeds to step 103. If not, the process returns to step 101.

  When the accelerator pedal is in the released state, the generated voltage V1 of the generator 15 and the generated voltage V2 of the generator 16 are detected by the voltage detection circuit 28 in step 103, respectively. In step 104, the generated voltages V1 and V2 of the generators 15 and 16 are respectively compared with an upper limit voltage (hereinafter referred to as a charging upper limit voltage) Vo that can charge the battery. When it is determined that the power generation voltages V1 and V2 of the two generators 15 and 16 are both equal to or lower than the charging upper limit voltage Vo, the routine proceeds to step 105, where the generator battery switching circuit 26 generates the power generation voltages V1 and V2 and the charging states C1 and C2. The connection between the generators 15 and 16 and the batteries 13 and 14 is switched accordingly.

  Basically, the generator with the higher generation voltage is connected to the battery with the lower state of charge SOC. That is, when V1 <V2 and C1 <C2, the generator 16 having a high power generation voltage V2 is connected to the battery 13 having a low charge state C1, and the power generator 15 having a low power generation voltage V1 and the battery 14 having a high charge state C2. Connect. When V1> V2 and C1 <C2, the generator 15 having a high power generation voltage V1 is connected to the battery 13 having a low charge state C1, and the power generator 16 having a low power generation voltage V2 and the battery 14 having a high charge state C2. Connect.

  Further, in the case of V1 <V2 and C1> C2, a generator 16 having a high generation voltage V2 and a battery 14 having a low charge state C2 are connected, and a generator 15 having a low generation voltage V1 and a battery 13 having a high charge state C1 are connected. Connect. Furthermore, when V1> V2 and C1> C2, a generator 15 having a high generation voltage V1 is connected to a battery 14 having a low charge state C2, and a generator 16 having a low generation voltage V2 and a battery having a high charge voltage C1. 13 is connected.

  If it is determined in step 104 that the power generation voltages V1 and V2 of the generators 15 and 16 are not less than or equal to the charging upper limit voltage Vo of the electric brake dedicated batteries 13 and 14, the process proceeds to step 106 where both the power generation voltages V1 and V2 are upper charging limits. It is determined whether or not the voltage Vo is exceeded. When the power generation voltages V1 and V2 exceed the charging upper limit voltage Vo, the batteries 13 and 14 cannot be charged by the power generators 15 and 16, so the power generators 15 and 16 and the batteries 13 and 14 are connected. Instead, the process proceeds to step 108.

  On the other hand, if one of the power generation voltages V1, V2 of the generators 15, 16 exceeds the charging upper limit voltage Vo and the other is lower than the charging upper limit voltage Vo, the process proceeds to step 107. In this case, charging is performed by connecting a generator having a power generation voltage equal to or lower than the charging upper limit voltage Vo to a battery having a lower state of charge SOC.

  Specifically, when V2 ≦ Vo and C1 <C2, that is, the generator 16 whose generated voltage V2 is equal to or lower than the charging upper limit voltage Vo is connected to the battery 13 whose charging state C1 is low. In the case of V2 ≦ Vo and C1> C2, that is, the generator 16 whose generated voltage V2 is equal to or lower than the charging upper limit voltage Vo is connected to the battery 14 whose charging state C2 is low. Further, when V1 ≦ Vo and C1 <C2, that is, the generator 15 whose generated voltage V1 is equal to or lower than the charging upper limit voltage Vo is connected to the battery 13 whose charge state C1 is low. Furthermore, when V1 ≦ Vo and C1> C2, that is, the generator 15 whose generated voltage V1 is equal to or lower than the charging upper limit voltage Vo is connected to the battery 14 whose charging state C2 is low.

  Here, for example, considering a case where the vehicle passes through a curved road, a speed difference is generated in the wheels 1 to 4 due to traveling on the curved road, and a difference is generated in the generated voltages V1 and V2 of the generators 15 and 16. As shown in FIG. 3, when the vehicle passes the left curved road, the speed of the right rear wheel 2 becomes higher than the speed of the left rear wheel 4, and the generated voltage V <b> 1 of the generator 15 is It becomes higher than the generated voltage V2.

  In the conventional electric brake device, since the connection between the generator and the battery dedicated to the electric brake is fixed, if there is a difference in the generated voltage of the generator in the traveling environment of the vehicle as shown in FIG. A high-power generator may charge a battery having a high state of charge SOC, and only a specific battery may be overcharged and deteriorate.

  Further, in the conventional electric brake device, the vehicle traveling speed is detected by, for example, a vehicle speed pulse sensor that rotates in conjunction with the output shaft of the transmission, and when the traveling speed exceeds a predetermined speed, charging of the battery by the generator is stopped. Prevents overcharging of the battery for electric brakes. However, even if the vehicle speed detected by the vehicle speed pulse sensor is less than a predetermined speed, the speed of the wheel on one side may become high depending on the traveling environment such as traveling on a curved road, and the generated voltage of the generator is There is a problem that the charge upper limit voltage Vo of the dedicated battery is exceeded, and the battery deteriorates.

  In order to prevent such a problem, it is conceivable to detect the speed of each wheel, determine the vehicle speed based on the highest speed, and stop charging the battery by the generator when the vehicle speed exceeds a predetermined speed. However, in this method, charging is not performed even if the power generation voltage of the generator provided on the wheel rotating at a low speed is equal to or lower than the charging upper limit voltage Vo of the battery. The function of recovering the battery as regenerative power is lost.

  Therefore, in this embodiment, the voltage detection circuit 28 detects the power generation voltages of the generators 15 and 16, and the battery charge state detection device 27 detects the charge state SOC of the electric brake dedicated batteries 13 and 14, thereby generating power. When the generated voltages V1 and V2 of the machines 15 and 16 are both equal to or lower than the charging upper limit voltage Vo, the generator with the higher generated voltage is connected to the battery with the lower charged state SOC and the generator with the lower generated voltage The generator battery switching circuit 26 switches the connection between the generators 15 and 16 and the electric brake dedicated batteries 13 and 14 so that the generator is connected to the battery having the higher state of charge SOC.

  In the example shown in FIG. 3, a generator 15 that generates a high voltage at a high rotation speed is connected to a battery 14 with a low state of charge SOC and charged with a large charge power, and a generator 16 that generates a low voltage at a low rotation speed. Is connected to the battery 13 having a high state of charge SOC and charging is performed with a small charge power.

  By providing such a configuration, according to one embodiment, when charging the electric brake dedicated batteries 13 and 14 with the electric power generated by the generators 15 and 16, the battery 13, with a voltage exceeding the charging upper limit voltage Vo, 14, while charging a battery with a low state of charge SOC, a large amount of charging current flows from a generator with a high generation voltage, and conversely, a battery with a high state of charge SOC has a low generation voltage. A small charging current flows from the generator, and even if there is a difference in the state of charge SOC of the batteries 13 and 14, charging can be performed so that the state of charge finally becomes almost the same state SOC. Therefore, unlike the conventional electric brake device, even if the left and right wheel speeds are different depending on the traveling environment of the vehicle, a situation in which the battery is deteriorated due to uneven charging of one battery is prevented.

  In one embodiment, as long as there is a generator whose generated voltage is equal to or lower than the charging upper limit voltage Vo, a battery having a low state of charge SOC is charged by the generator, so that compared to a conventional electric brake device, A lot of running energy can be recovered.

  After completing the connection process between the generators 15 and 16 and the batteries 13 and 14 for the electric brakes, it is confirmed in step 108 in FIG. 2 whether or not the brake pedal is depressed by the brake sensor 24 and the brake pedal is depressed. If not, the process returns to step 101 and the above-described processing is repeated.

  When the brake pedal is depressed, the routine proceeds to step 109, where the battery brake switching circuit 25 connects the electric brake dedicated batteries 13, 14 and the electric brake actuators 5-8 according to the charging states C1, C2 and the target brake force. . Basically, a battery having a higher state of charge SOC is connected to an electric brake actuator that requires a strong braking force.

  That is, when the charging state C2 of the battery 14 is higher than the charging state C1 of the battery 13, the battery 14 and an electric brake actuator that requires a strong braking force are connected, and the battery 13 and the remaining electric brake actuators are connected. When the charging state C1 of the battery 13 is higher than the charging state C2 of the battery 14, the battery 13 and an electric brake actuator that requires a strong braking force are connected, and the battery 14 and the remaining electric brake actuators are connected.

  Here, in order to prevent the spin and the deviation of the traveling path and improve the safety of the vehicle, a VDC (Vehicle Dynamics Control) device or a TCS (Traction Control) that controls the braking force of each wheel to stabilize the behavior of the vehicle. System) device has been put into practical use. When such an apparatus is realized using an electric brake device, a difference in braking force is inevitably generated in each wheel, so that the electric power supplied from the electric brake dedicated battery is also different for each brake actuator. In addition, even when an ABS (Anti-lock Brake System) device that prevents the wheels from being locked by the brake is operated, the target braking force at each wheel varies depending on the conditions such as the friction coefficient of the road surface. The electric power supplied from the battery for electric brakes is also different for each brake actuator.

  If a long-term bias in the difference in braking force occurs due to the vehicle's usage environment, etc., the connection between the battery for exclusive use of the electric brake and the electric brake actuator is fixed in the conventional electric brake device, so the state of charge of the battery SOC There is a problem in that deterioration occurs only in a specific battery due to bias.

  For example, as shown in FIG. 4, the state of charge SOC of the battery 14 is higher than the state of charge SOC of the battery 13, and the target braking force of the right front wheel 1 and the left rear wheel 4 is the target of the right rear wheel 2 and the left front wheel 3. When the braking force is greater than the braking force, a battery 14 having a high state of charge SOC is connected to the electric brake actuator 5 of the right front wheel 1 and the electric brake actuator 4 of the left rear wheel 4 having a large target braking force to supply a large amount of power. The battery 13 having a low state of charge SOC is connected to the electric brake actuator 6 of the right rear wheel 2 and the electric brake actuator 7 of the left front wheel 3 having a small target brake force to supply small electric power.

  As described above, according to the embodiment, the state of charge SOC of the electric brake dedicated batteries 13 and 14 is detected, the target brake force of the electric brake actuators 5 to 8 is obtained, and the battery with a high state of charge SOC is obtained. The electric brake actuator with a large target brake force is connected to supply a large amount of power, and the battery with a low state of charge SOC and the electric brake actuator with a small target brake force are connected to supply a small amount of power. The state of charge SOC of the battery can always be maintained at substantially the same value, and a situation in which the amount of discharge of a specific battery increases and deterioration progresses as in a conventional electric brake device is prevented.

  The correspondence between the constituent elements of the claims and the constituent elements of the embodiment is as follows. That is, the battery charge state detection device 27 constitutes a charge state detection means, the battery brake switching circuit 25 and the generator battery switching circuit 26 constitute a connection switching means, and the voltage detection circuit 28 constitutes a voltage detection means. The above description is merely an example, and when interpreting the invention, the correspondence between the items described in the above embodiment and the items described in the claims is not limited or restricted.

  In the embodiment described above, an example in which an electric brake actuator is installed on each of the front, rear, left and right wheels of the vehicle and a generator is installed on each of the left and right rear wheels, and two electric brake dedicated batteries are used. As shown, the number of electric brake actuators, the number of generators, and the number of batteries for electric brakes only need to be two or more, and the arrangement of the electric brake actuators and generators is also limited to the above-described embodiment. is not.

It is a figure which shows the structure of one embodiment. It is a flowchart which shows operation | movement of one Embodiment. It is a figure which shows the example of a connection of a generator and a battery. It is a figure which shows the example of a connection of a battery and an electric brake actuator.

Explanation of symbols

5-8 Electric brake actuators 13 and 14 Electric brake dedicated batteries 15 and 16 Generators 18 and 20 Controller 23 Accelerator sensor 24 Brake sensor 25 Battery brake switching circuit 26 Generator battery switching circuit 27 Battery charge state detection device 28 Voltage detection circuit

Claims (3)

A plurality of electric brake actuators installed on a plurality of wheels of the vehicle and generating a braking force corresponding to a target braking force for each wheel;
A plurality of batteries for supplying power to the actuator;
Charge state detection means for detecting the charge state of each battery;
A battery having a high charge state among the plurality of batteries and an actuator having a high target braking force among the plurality of actuators are connected, and a battery having a low charge state among the plurality of batteries and the plurality of actuators are connected. An electric brake device comprising a connection switching means for connecting an actuator having a low target brake force. In the electric brake device according to claim 1,
A plurality of generators installed on a plurality of wheels of the vehicle for charging the plurality of batteries;
Voltage detecting means for detecting the power generation voltage of each of the generators,
The connection switching means connects a generator having a high generation voltage among the plurality of generators and a battery having a low charge state among the plurality of batteries, and generates a voltage generated from the plurality of generators. An electric brake device comprising: a low generator connected to a battery having a high charge state among the plurality of batteries. In the electric brake device according to claim 2,
The connection switching means releases the connection between the power generator and the battery when the power generation voltage of the power generator exceeds an upper limit voltage capable of charging the battery.

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