JP5766240B2 - Braking device for vehicle - Google Patents

Description

  The present invention relates to a vehicular braking apparatus that executes antilock brake control by applying regenerative braking torque or friction braking torque to wheels according to the state of the vehicle.

  It is generally known that so-called anti-lock brake control is effective in order to prevent the vehicle from spinning and braking distance from becoming longer due to the wheels locking on a slippery road surface or the like. .

  Also, as a system for applying braking torque to wheels when executing anti-lock braking control, not only a conventional braking mechanism that applies friction braking torque but also a regenerative braking mechanism that uses an electric motor that applies regenerative braking torque is combined. The system has attracted attention (for example, see Patent Documents 1 and 2).

JP-A-11-205905 JP-A-10-203351

However, the prior art has the following problems.
In the prior art described in Patent Document 1, the maximum regenerative braking torque (maximum regenerative braking torque that can be applied to the wheel by the electric motor) is applied to the wheels when the vehicle goes straight without considering the road surface condition. The appropriate braking force can not be obtained. As a result, there is a problem that the vehicle state may become unstable or the braking distance of the vehicle may become long depending on the road surface state.

  Moreover, in the prior art described in Patent Document 2, since the regenerative braking torque is applied without considering the slip ratio of the wheels, an appropriate braking force corresponding to the state of the vehicle cannot be obtained. As a result, there is a problem that the braking distance of the vehicle may become long depending on the road surface condition.

  The present invention has been made to solve the above-described problems, and according to the state of the vehicle, an appropriate braking force and cornering force can be obtained, and the braking distance of the vehicle is made as short as possible. An object of the present invention is to obtain a vehicular braking apparatus that can achieve the turning required by the driver.

  The vehicle braking device according to the present invention includes a battery that charges and discharges electric power, power is supplied from the battery and a driving torque is applied to the wheel to drive the wheel, and a regenerative braking torque is applied to the wheel to regenerate electric power to the battery. There are a driving / regenerative braking unit that supplies the vehicle, a friction braking unit that applies friction braking torque to the wheels, a steering state detection unit that detects a steering state corresponding to the size of the steering wheel angle of the vehicle, and a brake operation by the driver. In this case, the braking of the wheel constituted by the first wheel to which the regenerative braking torque and the friction braking torque can be individually applied and the second wheel to which only the friction braking torque can be applied is (vehicle speed−wheel Speed) / control unit for controlling based on the slip ratio defined as the vehicle body speed, and the control unit is configured to brake the second wheel. Depending on the operation, a friction braking torque is applied via the friction braking unit so that the slip ratio becomes a friction braking target slip ratio that prevents the second wheel from being locked, and the first wheel is subjected to the brake operation. Thus, the regenerative braking torque is applied via the drive / regenerative braking unit so that the slip rate becomes the regenerative braking target slip rate for preventing the first wheel from being locked, and the slip state is determined according to the steering state detected by the steering state detecting unit. Thus, the regenerative braking target slip ratio is changed.

  According to the present invention, when the antilock brake control is executed, the regenerative braking torque or the friction braking torque is set as the braking torque so that the slip ratio of each wheel becomes the target slip ratio set according to the state of the vehicle. Add individually for each wheel. As a result, an appropriate braking force and cornering force can be obtained according to the state of the vehicle, the vehicle braking distance can be shortened as much as possible, and the turning required by the driver can be realized. Braking device can be obtained.

It is a figure which shows schematic structure of the vehicle by which the vehicle braking device in Embodiment 1 of this invention is mounted. In Embodiment 1 of this invention, it is explanatory drawing which shows an example of the relationship between the braking force with respect to a slip ratio, and a cornering force. It is a flowchart which shows a series of operation | movement procedures of the vehicle braking device in Embodiment 1 of this invention.

  Hereinafter, a vehicle braking device according to the present invention will be described with reference to the drawings according to a preferred embodiment. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a schematic configuration of a vehicle on which a vehicle braking device according to Embodiment 1 of the present invention is mounted. In the following, a case will be described in which the vehicle braking device according to the first embodiment is applied to a four-wheel drive vehicle driven by electric motors provided on the left and right rear wheels.

  In FIG. 1, the vehicle includes wheels 11a to 11d (left rear wheel 11a, right rear wheel 11b, left front wheel 11c, right front wheel 11d). Further, the driving torque or the friction braking torque is applied to the left rear wheel 11a by the first driving / regenerative braking unit 12a and the right rear wheel 11b by the second driving / regenerative braking unit 12b, respectively. The drive / regenerative braking units 12a and 12b include, for example, an electric motor (motor) and an inverter.

  The first drive / regenerative braking unit 12a and the second drive / regenerative braking unit 12b are provided so that power can be transmitted to the corresponding left and right rear wheels 11a, 11b. The first drive / regenerative braking unit 12a and the second drive / regenerative braking unit 12b are electrically connected to a battery 13 provided in the vehicle, and can exchange power with the battery 13.

  An electronic control unit (ECU) 14 included in the vehicle braking device is electrically connected to the first drive / regenerative braking unit 12a and the second drive / regenerative braking unit 12b. The first drive / regenerative braking unit 12 a and the second drive / regenerative braking unit 12 b operate as an electric motor or a generator based on a control command from the ECU 14. That is, when operating as an electric motor, a driving torque generated by supplying electric power from the battery 13 is applied to the left and right rear wheels 11a and 11b to drive the wheels. On the other hand, when operating as a generator, regenerative braking torque is applied to the left and right rear wheels 11 a and 11 b to brake the wheels, and regenerative power is supplied to the battery 13.

  In this way, the ECU 14 controls the motor torque independently of the rotation of the first drive / regenerative braking unit 12a and the second drive / regenerative braking unit 12b, and thereby the drive torque applied to the left and right rear wheels 11a, 11b and The braking torque can be controlled independently.

  Further, a battery sensor (not shown) is electrically connected to the ECU 14 as an example of a battery charge state detection unit that detects a battery state such as a voltage between terminals of the battery 13, a charge / discharge current, or a battery temperature. . The ECU 14 measures various states of the battery 13 based on the detection result of the battery sensor, and measures the battery capacity (charging rate).

  In addition to the regenerative braking torque by the first drive / regenerative braking unit 12a and the second drive / regenerative braking unit 12b, a friction braking unit is provided that applies friction braking torque to each of the wheels 11a to 11d.

  As shown in FIG. 1, as an example of the friction braking unit, the wheels 11 a to 11 b are controlled by the hydraulic pressure of the brake actuator 15 adjusted based on the operation amount (brake stroke amount) of the driver's brake pedal (not shown). What is necessary is just to comprise so that friction brake torque may be added when the brake calipers 16a-16d provided in 11d operate | move. In this case, the ECU 14 adjusts and controls the hydraulic pressure of the brake actuator 15 based on the brake stroke amount of the driver.

  The ECU 14 is electrically connected to wheel speed sensors 17a to 17d provided on the wheels 11a to 11d, respectively. ECU14 detects each speed (wheel speed) of wheels 11a-11d based on the output of wheel speed sensors 17a-17d, and also detects vehicle body speed. Moreover, ECU14 calculates the slip ratio of each wheel 11a-11d mentioned later based on the detected wheel speed and vehicle body speed. In addition, regarding the vehicle body speed detection method, for example, a known technique such as estimation from a deceleration gradient of the wheel speed output from the wheel speed sensors 17a to 17d may be applied.

  In addition, a handle angle sensor 19 is electrically connected to the ECU 14 as an example of a steering state detection unit that detects a steering state. The handle angle sensor 19 is provided on the handle 18. The ECU 14 detects the steering wheel angle based on the output of the steering wheel angle sensor 19 and detects the steering operation state (steering state) of the driver.

  Next, the brake control operation by the vehicle braking apparatus in the first embodiment will be described with reference to FIG. FIG. 2 is an explanatory diagram showing an example of the relationship between the braking force and the cornering force with respect to the slip ratio in the first embodiment of the present invention.

  First, an example of the relationship between the braking force and the cornering force with respect to the slip ratio in FIG. 2 will be described. The slip ratio (wheel slip ratio) shown in FIG. 2 means a ratio of speed obtained by subtracting the wheel speed from the vehicle speed to the vehicle speed (= (vehicle speed−wheel speed) / vehicle speed). Further, the braking force means a braking force generated between the wheel (tire) and the road surface.

  For example, when the wheel is in a locked state, the wheel speed is 0, so the slip rate is 1. Further, as shown in FIG. 2, the braking force increases as the slip ratio increases, but after reaching a maximum value at a certain slip ratio, it decreases at a slip ratio higher than that. On the other hand, the cornering force decreases monotonously as the slip ratio increases. When the cornering force is reduced, it is difficult to turn because a lateral force cannot be applied to the wheel even if the steering wheel is operated.

  Note that it is generally known that on a sliding road surface (for example, a slippery road surface such as a snowy road), both braking force and cornering force are greatly reduced as compared to a normal road surface (for example, dry asphalt). ing.

  Further, ideally, the braking distance can be minimized by controlling the slip ratio of the wheel to the slip ratio (see FIG. 2) when the braking force becomes the maximum value. On the other hand, the slip rate when the cornering force reaches the maximum value is 0. In this case, the braking force is 0.

  Here, in the conventional anti-lock brake control, for example, a mechanical brake is used, the brake caliper is operated by the hydraulic pressure of the brake actuator, and the brake caliper comes into contact with the brake disc so that friction braking torque is applied to the wheels. Added. Therefore, considering the delay in hydraulic pressure, the delay in mechanical movement of the brake caliper, and the cornering force, etc., the slip ratio of the wheel is set to be smaller than the slip ratio when the braking force reaches the maximum value. It is common to control the slip ratio.

  On the other hand, in a vehicle equipped with an electric motor capable of driving / regeneratively braking each wheel, the regenerative braking torque can be applied to the wheel as a braking torque. Therefore, there is no response delay like the conventional friction braking torque, and it is possible to reach the target braking torque command (target value) within 10 msec, for example. The present invention proposes a braking device for a vehicle that performs a new brake control (anti-lock brake control) using such responsiveness of the electric motor.

  Next, the case where the antilock brake control is not performed in the brake control operation by the vehicle braking device in the first embodiment will be described.

  For example, when the vehicle brake operation is performed on a normal road surface, the anti-lock brake control is not performed unless the slip ratio is small and the driver demands rapid braking. In this case, the ECU 14 applies a braking torque to the wheels 11a to 11d based on the brake stroke amount of the driver, for example. That is, in the first embodiment, the ECU 14 preferentially applies the regenerative braking torque to the left and right rear wheels 11a, 11b and, if insufficient, applies the friction braking torque together and friction brakes to the left and right front wheels 11c, 11d. Torque will be applied.

  Specifically, the ECU 14 does not need to apply the friction braking torque if the deceleration required by the driver is obtained by applying the regenerative braking torque to the left and right rear wheels 11a and 11b. As described above, in the system in which the regenerative braking torque and the friction braking torque can be individually applied to the wheels as the braking torque, the regenerative braking torque is preferentially applied. And since the deceleration energy of the vehicle consumed as heat by applying friction braking torque to the wheels can be stored in the battery 13, there is an advantage that the fuel efficiency is improved and the cruising distance is extended.

  On the other hand, if the deceleration requested by the driver is not obtained even if the regenerative braking torque is applied to the wheels, the ECU 14 operates the friction control unit to also apply the friction braking torque to the left and right rear wheels 11a and 11b. Will be added. Although detailed description is omitted because it is not directly related to the present invention, it is preferable to control the regenerative braking torque so that the driver does not feel uncomfortable when applying the friction braking torque. .

  Next, a case where antilock brake control is performed in the brake control operation by the vehicle braking device will be described. The role of the anti-lock brake control is to avoid the locked state of the wheel and shorten the braking distance while ensuring the turning performance of the vehicle with respect to the driver's steering operation.

  For example, when a vehicle brake operation is performed on a sliding road surface, or when there is a request for sudden braking by the driver, the slip ratio is large, and antilock brake control is performed. The ECU 14 applies regenerative braking torque and friction braking torque to the left and right rear wheels 11a and 11b, and applies friction braking torque to the left and right front wheels 11c and 11d.

  Specifically, the ECU 14 applies friction braking torque to the left and right front wheels 11c and 11d so that the slip ratio of the left and right front wheels 11c and 11d becomes the friction braking target slip ratio. Note that the friction braking target slip ratio corresponds to the slip ratio for preventing the wheel from being locked, and it is necessary to take into account the delay in hydraulic pressure, the mechanical movement of the brake caliper, the cornering force, etc. What is necessary is just to prescribe | regulate according to motive power.

  On the other hand, the ECU 14 applies only the regenerative braking torque to the left and right rear wheels 11a and 11b so that the slip ratio of the left and right rear wheels 11a and 11b becomes the first regenerative braking target slip ratio. That is, the ECU 14 does not apply the friction braking torque if the torque necessary for controlling the slip ratio can be secured by applying only the regenerative braking torque to the left and right rear wheels 11a and 11b.

  Note that the first regenerative braking target slip ratio corresponds to a slip ratio for preventing the wheels from being locked, and may be defined in advance according to the required braking force. For example, as shown in FIG. 2, if the slip rate when the braking force reaches the maximum value is defined as the first regenerative braking target slip rate, the braking force by the anti-lock brake control becomes the maximum. The distance can be shortened.

  Further, when the ECU 14 applies only the regenerative braking torque to the left and right rear wheels 11a and 11b so that the slip ratio of the left and right rear wheels 11a and 11b becomes the first regenerative braking target slip ratio, the regenerative braking torque is set to the maximum regenerative braking torque. Even if the braking torque is reached, the slip ratio may not be controlled. The maximum regenerative braking torque means the maximum regenerative braking torque that can be applied to the left and right rear wheels 11a and 11b in terms of the performance of the first drive / regenerative braking unit 12a and the second drive / regenerative braking unit 12b. In such a case, the ECU 14 applies friction braking torque to the left and right rear wheels 11a and 11b together with the regenerative braking torque so that the slip ratio of the left and right rear wheels 11a and 11b becomes the friction braking target slip ratio. That is, even if the maximum regenerative braking torque is applied to the left and right rear wheels 11a, 11b, the torque necessary for controlling the slip ratio cannot be secured. Therefore, the friction braking torque is applied together to cover the shortage.

  In this way, the ECU 14 applies the friction braking torque by the friction braking unit to the left and right rear wheels 11a and 11b as necessary, and the slip ratio of the left and right rear wheels 11a and 11b becomes the friction braking target slip ratio. So that it is controlled. As a result, when it is not necessary to apply the friction braking torque with respect to the braking distance and the turning performance of the vehicle at the time of the steering operation, it is necessary to ensure the performance superior to the conventional and to apply the friction braking torque. Even if it is a case, the performance equivalent to the past can be ensured.

  In addition, due to the performance of the battery 13, the regenerative braking torque applied to the left and right rear wheels 11a, 11b may be reduced depending on the state of charge. In such a case, if the charge rate (charge amount) of the battery 13 detected by the battery charge state detection unit is equal to or less than the first charge rate (for example, 95%), the ECU 14 applies regeneration to the left and right rear wheels 11a and 11b. The braking torque is decreased according to the charging rate of the battery 13. Then, the ECU 14 controls the slip ratio of the left and right rear wheels 11a and 11b to be the first regenerative braking target slip ratio only by the regenerative braking torque after the decrease. Further, the ECU 14 performs the same operation as above if the slip ratio of the left and right rear wheels 11a, 11b cannot be controlled to be the first regenerative braking target slip ratio only by the regenerative braking torque after the decrease. That is, the ECU 14 applies friction braking torque to the left and right rear wheels 11a and 11b together with the reduced regenerative braking torque so that the slip ratio of the left and right rear wheels 11a and 11b becomes the friction braking target slip ratio.

  The first charging rate is specified in advance according to the performance of the battery 13, and the regenerative braking torque applied to the left and right rear wheels 11a, 11b is changed in advance in accordance with how the battery 13 is charged. The ECU 14 may be configured by defining.

  In this way, the regenerative braking torque applied to the left and right rear wheels 11a, 11b is reduced according to the charging rate of the battery 13, so that overcharging does not occur. In addition, the regenerative braking torque is not lost during charging, so that the driver does not feel uncomfortable.

  In addition, the cornering force may be increased according to the steering state in order to ensure the turning performance of the vehicle. In such a case, if the ECU 14 determines that the first steering state has been detected based on the detection result of the steering state detection unit, the ECU 14 sets the second value according to the steering state as a target value instead of the first regenerative braking target slip ratio. Change the regenerative braking target slip ratio. Further, the ECU 14 changes the regenerative braking torque applied to the rear wheels 11a and 11b so that the slip ratio of the rear wheels 11a and 11b becomes the changed second regenerative braking target slip ratio.

  Regarding the detection determination of the steering state by the ECU 14, for example, when the steering angle of the vehicle is equal to or larger than the first steering wheel angle (for example, 30 °), it is determined that the first steering state is detected, and the steering angle is less than the first steering wheel angle. What is necessary is just to comprise so that it may determine with having not detected the 1st steering state. Further, the second regenerative braking target slip ratio corresponds to a slip ratio for preventing the wheels from being locked, and the ECU 14 may be configured by preliminarily defining how to change in multiple stages according to the steering state. In this case, it is preferable that the second regenerative braking target slip ratio to be changed becomes smaller as the steering angle of the vehicle detected by the steering state detection unit becomes larger. Further, the first handle angle may be defined in advance according to the vehicle speed, the vehicle, or the like.

  In this way, by controlling the slip ratio of the rear wheels 11a and 11b to be the second regenerative braking target slip ratio set according to the steering state, the balance between the braking force and the cornering force can be made compatible. In addition to the braking performance, the turning performance can be secured.

  The first regenerative braking target slip ratio, the second regenerative braking target slip ratio, and the friction braking target slip ratio described above are defined in advance in consideration of the type of vehicle. Further, since it is not directly related to the present invention, a detailed description is omitted, but a known technique may be used to learn and set a slip ratio that maximizes the braking force.

  Next, a series of operations of the vehicle braking device in the first embodiment will be specifically described with reference to the flowchart of FIG. FIG. 3 is a flowchart showing a series of operation procedures of the vehicle braking apparatus according to Embodiment 1 of the present invention.

  First, in step S301, the ECU 14 applies the regenerative braking torque to the left and right rear wheels 11a and 11b based on the brake operation by the driver, so that the slip ratio of the left and right rear wheels 11a and 11b becomes the first regenerative braking target slip. It is determined whether the rate is equal to or greater than the rate.

  In step S301, when the slip ratio of the left and right rear wheels 11a and 11b is less than the first regenerative braking target slip ratio, the ECU 14 ends the series of processes. That is, as described above, when the vehicle brake operation is performed on a normal road surface, the slip rate of the left and right rear wheels 11a and 11b is less than the first regenerative braking target slip rate, unless there is a sudden braking request from the driver. Become. In such a case, it is not necessary to execute the anti-lock brake control, so the process proceeds to END.

  On the other hand, if the slip ratio of the left and right rear wheels 11a, 11b is greater than or equal to the first regenerative braking target slip ratio in step S301, the ECU 14 proceeds to step S302. That is, as described above, when a braking operation of the vehicle is performed on a sliding road surface, or when the driver demands rapid braking, the braking force becomes the maximum torque because the tire force is limited, and the left and right rear wheels 11a, 11b The slip ratio may be greater than or equal to the first regenerative braking target slip ratio. In such a case, since it is necessary to perform anti-lock brake control, the process proceeds to step S302.

  In step S302, the ECU 14 determines whether or not the regenerative braking torque applied to the left and right rear wheels 11a and 11b is equal to or less than the maximum regenerative braking torque.

  In step S302, when the regenerative braking torque applied to the left and right rear wheels 11a and 11b is equal to or less than the maximum regenerative braking torque, the ECU 14 satisfies the torque necessary for controlling the slip ratio only with the regenerative braking torque. Proceed to step S303. On the other hand, in step S302, when the regenerative braking torque applied to the left and right rear wheels 11a and 11b is larger than the maximum regenerative braking torque, the ECU 14 lacks the torque necessary to control the slip ratio with only the regenerative braking torque. Therefore, it progresses to step S305.

  In step S303, the ECU 14 determines whether or not the current charging rate of the battery 13 is equal to or lower than the first charging rate.

  In step S303, the ECU 14 proceeds to step S304 when the charging rate of the battery 13 is equal to or lower than the first charging rate. On the other hand, in step S303, when the charging rate of the battery 13 is larger than the first charging rate, the ECU 14 proceeds to step S305.

  In step S304, the ECU 14 applies the friction braking torque to the left and right front wheels 11c and 11d to control the operation of the friction braking unit so that the slip ratio of the left and right front wheels 11c and 11d becomes the friction braking target slip ratio.

  In step S304, the ECU 14 applies the regenerative braking torque to the left and right rear wheels 11a and 11b, so that the slip ratio of the left and right rear wheels 11c and 11d becomes the first regenerative braking target slip ratio. The operation of the braking unit 12a and the second drive / regenerative braking unit 12b is controlled. In this case, as described above, the ECU 14 does not apply the friction braking torque by the friction braking unit to the left and right rear wheels 11a and 11b. Then, after executing step S304, the ECU 14 proceeds to step S306.

  In step S305, as in step S304, the ECU 14 applies the friction braking torque to the left and right front wheels 11c and 11d so that the slip ratio of the left and right front wheels 11c and 11d becomes the friction braking target slip ratio. To control.

  Further, in step S305, the ECU 14 applies the regenerative braking torque and the friction braking torque to the left and right rear wheels 11a and 11b individually, so that the slip ratio of the left and right rear wheels 11a and 11b becomes the friction braking target slip ratio. The operations of the first drive / regenerative braking unit 12a, the second drive / regenerative braking unit 12b, and the friction braking unit are controlled. And ECU14 complete | finishes a series of processes, after performing step S305.

  In step S306, the ECU 14 determines whether or not a first steering state in which the steering wheel angle is equal to or larger than the first steering wheel angle has been detected. If the ECU 14 determines in step S306 that the first steering state has been detected, the ECU 14 proceeds to step S307.

  On the other hand, when it is determined in step S306 that the first steering state is not detected, the ECU 14 ends the series of processes. That is, in this case, since the driver's intention to travel is determined to be straight, the first regenerative braking target slip ratio is maintained as it is, and the braking force is controlled to be maximized.

  In step S307, the ECU 14 causes the first drive / regenerative braking unit 12a and the second drive so that the slip ratios of the left and right rear wheels 11a, 11b become the second regenerative braking target slip ratio set according to the current steering state. / Controls the operation of the regenerative braking unit 12b. And ECU14 complete | finishes a series of processes, after performing step S307.

  Thus, by changing the slip ratio in multiple stages according to the steering state, both braking performance and turning performance can be achieved. In addition, it becomes possible to implement | achieve the braking feeling without a sense of incongruity with respect to a driver | operator by changing a slip ratio only with respect to the wheel (right-and-left rear wheels 11a and 11b) in which regenerative braking torque is generated.

  As described above, according to the first embodiment, the regenerative braking torque and the friction braking torque applied to the wheels are independently controlled, and the slip ratio of the wheel where the regenerative braking torque is generated is the slip ratio at which the braking force becomes the maximum value. By controlling so as to become, the braking distance of the vehicle can be shortened compared with the conventional one. In addition, by detecting the steering condition and controlling the slip ratio of the wheel that generates regenerative braking torque to be the regenerative braking target slip ratio corresponding to the detected steering condition, the turning performance required by the driver is secured. This makes it possible to achieve both braking performance and turning performance, which were difficult with conventional mechanical antilock brake control.

  In the first embodiment, a vehicle in which an electric motor is disposed on two rear wheels has been described as an example. However, for example, the present invention is applied to an in-wheel motor in which an electric motor is embedded in a vehicle or a tire in which motors are disposed in all four wheels. Even if is applied, it is possible to obtain the same effect.

  Further, for example, even in a vehicle having only one electric motor, the present invention can be applied if braking torque can be applied independently on the left and right sides by setting the differential gear. That is, the present invention can be applied to any vehicle that can apply regenerative torque by an electric motor to wheels.

  Further, in the first embodiment, it has been described that the control is performed so that the slip ratio of the wheel to which the friction braking torque is applied becomes the friction braking target slip ratio. Here, since a friction braking force is applied by contact between the brake caliper and the brake pad, there are many control operation examples in which an ON / OFF operation is performed such that the brake is released if a wheel lock is detected. Therefore, regarding the wheel to which the friction braking torque is applied, the same effect can be obtained even if the slip ratio is controlled to be the friction braking target slip ratio by turning ON / OFF the generation of the friction braking torque. By controlling in this way, it becomes possible to simplify the friction braking algorithm, and the feasibility becomes easy.

  In the first embodiment, the case where the steering wheel angle is used for the detection of the steering state is exemplified. However, for example, the same effect can be obtained by using the steering torque of the driver. That is, the driver's steering torque can be used as a signal that more faithfully represents the driver's intention in order to operate the steering wheel in the desired direction. As described above, the steering state can be detected with higher accuracy by using the steering torque signal.

  11a, 11b Left and right rear wheels, 11c, 11d Left and right front wheels, 12a First drive / regenerative braking unit, 12b Second drive / regenerative braking unit, 13 Battery, 14 ECU (control unit), 15 Brake actuator, 16a-16d Brake caliper , 17a to 17d Wheel speed sensor, 18 steering wheel, 19 steering wheel angle sensor (steering state detection unit).

Claims (4)

A battery that charges and discharges power;
A drive / regenerative braking unit for supplying power from the battery to drive the wheel by applying a driving torque to the wheel, and supplying regenerative power to the battery by applying a regenerative braking torque to the wheel;
A friction braking portion for applying a friction braking torque to the wheel;
A steering state detector that detects a steering state corresponding to the size of the steering wheel angle of the vehicle;
When a brake operation is performed by the driver, the regenerative braking torque and the friction braking torque can be individually added to the first wheel, and the second wheel can be applied only with the friction braking torque. A control unit that controls braking of the wheel based on a slip ratio defined as (body speed−wheel speed) / body speed;
A vehicle braking device comprising:
The controller is
For the second wheel, the friction braking torque is applied via the friction braking unit so that the slip ratio becomes a friction braking target slip ratio for preventing the second wheel from being locked according to the brake operation. Add
With respect to the first wheel, the regenerative braking unit is configured to provide the regenerative braking target slip ratio to prevent the first wheel from being locked in accordance with the brake operation. A braking device for a vehicle that applies braking torque and changes the regenerative braking target slip ratio in accordance with the steering state detected by the steering state detector. The vehicle braking device according to claim 1,
The control unit, when performing the torque control of the first wheel, when the regenerative braking target slip ratio is not reached even when the maximum regenerative braking torque that can be applied via the drive / regenerative braking unit is applied. Determines that the torque is insufficient with only the regenerative braking torque, and adds the insufficient torque as the friction braking torque via the friction braking unit, so that the slip ratio reaches the friction braking target slip ratio. The braking device for the vehicle to be controlled. The vehicle braking device according to claim 1,
A battery state detection unit for detecting a charge state of the battery;
The control unit changes the regenerative braking torque applied via the drive / regenerative braking unit according to the charging state detected by the battery state detection unit when performing torque control of the first wheel. In both cases, even if the maximum regenerative braking torque after change that can be applied via the drive / regenerative braking unit is applied and the regenerative braking target slip rate is not reached, the regenerative braking torque alone is insufficient. The vehicle braking device is configured to control the slip ratio to reach the friction braking target slip ratio by adding the insufficient torque as the friction braking torque through the friction braking section. The vehicle braking device according to any one of claims 1 to 3,
The control unit changes the regenerative braking target slip ratio so that the larger the detected value is, the smaller the detected value is, in accordance with the steering state detected by the steering state detection unit.

Images