JP2016111891A - Vehicular braking force controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a braking force at a desired front-and-rear distribution ratio by using a hydraulic brake device having no adjustment function of the front-and-rear distribution ratio.SOLUTION: A brake ECU sets target braking forces (Ff, Fr) of front and rear wheels on the basis of required deceleration α and ideal brake force distribution characteristics in a step S13. The brake ECU sets target hydraulic braking forces (Fpf, Fpr) of the front and rear wheels required for generating hydraulic brake deceleration in steps S14 and S15. The brake ECU sets target motor braking/driving forces (Fmf, Fmr) of the front and rear wheels on the basis of differences between the target braking forces and the target hydraulic braking forces in a step S16.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle braking force control device that brakes a wheel by both a regenerative braking force generated by a power generation action of a motor and a hydraulic braking force generated by hydraulic control of brake hydraulic oil.

  2. Description of the Related Art Conventionally, vehicles that generate driving force and braking force (called braking / driving force) on wheels by a motor are known. In such a vehicle, a braking force generated by bringing a brake pad into contact with a disk (or a drum) by hydraulic pressure, and a braking force generated by regenerating generated power in a battery by causing a motor driving a wheel to act as a generator. Use both to brake the wheel. The former braking force is called a hydraulic braking force, and the latter braking force is called a regenerative braking force.

  The required braking force required to decelerate the vehicle is distributed to the front and rear wheels. In this case, it is desirable to set the distribution of the required braking force to the front wheels and the rear wheels so that the distribution on the front wheel side increases as the required braking force increases. FIG. 5 shows an example of an ideal distribution characteristic between the braking force on the front wheel side and the braking force on the rear wheel side when the vehicle decelerates.

  In order to realize such distribution characteristics, the vehicle brake device proposed in Patent Document 1 is configured such that the hydraulic pressure supplied to the wheel cylinder can be independently controlled on the front wheel side and the rear wheel side. Specifically, a front wheel hydraulic circuit for supplying hydraulic pressure to the front wheel cylinder and a rear wheel hydraulic circuit for supplying hydraulic pressure to the rear wheel cylinder are provided independently in the hydraulic brake actuator, and the front wheel hydraulic circuit is provided. And a rear wheel hydraulic circuit are provided with linear control valves. Therefore, by controlling the opening degree of each linear control valve, the hydraulic pressure of the front wheel cylinder and the hydraulic pressure of the rear wheel cylinder downstream of each linear control valve can be controlled independently of each other. Can do. As a result, a braking force can be generated on the front and rear wheels so that a desired front-rear distribution ratio can be obtained.

JP 2006-21745 A

  However, in the vehicle brake device proposed in Patent Document 1, in order to generate a braking force with a desired front / rear distribution ratio, an independent hydraulic circuit is provided for the front and rear wheels, and a linear control valve is provided for each hydraulic circuit. Necessary. For this reason, the apparatus is complicated and the cost is increased.

  The present invention has been made to solve the above-described problems, and uses a hydraulic brake device that does not have a function of adjusting the front-rear distribution ratio so as to generate a braking force at a desired front-rear distribution ratio. The purpose is to do.

In order to achieve the above object, the features of the present invention are:
A hydraulic brake device (45, 40) that is operated by the hydraulic pressure of the brake hydraulic oil and generates a hydraulic braking force at a constant front-rear distribution ratio in the front and rear wheels (10f, 10r);
Motors (30f, 30r) for generating a braking / driving force on the front and rear wheels by transmitting to the front and rear wheels at least driving torque and regenerative braking torque independent of the front and rear wheels;
A battery (70) serving as a drive power source and a power regeneration destination of the motor;
Based on the required deceleration (α) required for decelerating the vehicle, and a preset ideal braking force distribution characteristic (L *) in which the front wheel front-rear distribution ratio increases as the required deceleration increases. Ideal target braking force setting means (S13) for setting ideal target braking forces (Ff, Fr) of the front and rear wheels;
When the maximum braking force that can be generated by power regeneration to the battery is generated by the motor, the braking force that needs to be generated by the hydraulic brake device to decelerate the vehicle at the required deceleration Target hydraulic braking force setting means (S14, S15) for setting the target hydraulic braking force (Fpf, Fpr) of the front and rear wheels by allocating at the constant front / rear distribution ratio;
Target motor braking / driving force setting means (S16) for setting the target motor braking / driving forces (Fmf, Fmr) of the front and rear wheels generated by the motor based on the difference between the ideal target braking force and the target hydraulic braking force. When,
Hydraulic control means (53, S18) for controlling the operation of the hydraulic brake device based on the target hydraulic braking force;
Motor control means (51, 52, 35f, 35r) for controlling the operation of the motor based on the target motor braking / driving force.

  The vehicle braking force generator of the present invention includes a hydraulic brake device, a motor, and a battery. The hydraulic brake device is operated by the hydraulic pressure of the brake hydraulic oil to generate a hydraulic braking force at a constant front-rear distribution ratio on the front and rear wheels. The motor generates a braking / driving force on the front and rear wheels by transmitting to the front and rear wheels at least a driving torque and a regenerative braking torque independent of the front and rear wheels. For example, the vehicular braking force generator may be configured to include a motor that drives the left and right front wheels in common and a motor that drives the left and right rear wheels in common. The structure provided with the motor may be sufficient. Moreover, the structure provided with the motor which drives one of the front and rear wheels in common and the two motors which drive the other independently of the left and right wheels may be used.

  The motor is connected to the battery, and driving power is supplied from the battery when transmitting driving torque to the wheels. Further, when the regenerative braking torque is transmitted to the wheels, the generated power is supplied to the battery.

  The vehicle braking force generator of the present invention includes an ideal target braking force setting means, a target hydraulic braking force setting means, and a target motor braking / driving force setting means in order to set the control amount of the hydraulic brake device and the motor. I have. The ideal target braking force setting means is based on a required deceleration required for decelerating the vehicle and a preset ideal braking force distribution characteristic in which the front-rear distribution ratio on the front wheel side increases as the required deceleration increases. Set the ideal target braking force for the front and rear wheels.

  When the ideal target braking force is generated only by the regenerative braking force by the motor, the regenerative braking torque can be controlled according to the ideal braking force distribution characteristic. However, since there is a limit to the braking force that can be generated by power regeneration to the battery, a hydraulic braking force may be required to decelerate the vehicle at the required deceleration. Therefore, in the present invention, the ideal target braking force is generated by the regenerative braking force and the hydraulic braking force.

  Therefore, the target hydraulic braking force setting means is generated in the hydraulic brake device to decelerate the vehicle at the required deceleration when the maximum braking force that can be generated by power regeneration to the battery is generated by the motor. The target hydraulic braking force for the front and rear wheels is set by distributing the braking force that needs to be distributed at a constant front-rear distribution ratio. The target motor braking / driving force setting means sets the target motor braking / driving force of the front and rear wheels generated by the motor based on the difference between the ideal target braking force and the target hydraulic braking force.

  The hydraulic control means controls the operation of the hydraulic brake device based on the target hydraulic braking force. The motor control means controls the operation of the motor based on the target motor braking / driving force. Thus, a combined force is generated on the wheel, which is a combination of the hydraulic braking force generated by the operation of the hydraulic brake device and the braking / driving force generated by the operation of the motor. As for the target motor braking / driving force, the total force generated by the motor acts as a braking force, but the force generated by each motor may act as a driving force.

  Therefore, even if the vehicle is equipped with a hydraulic brake device that does not have the function of adjusting the front / rear distribution ratio of the braking force, the braking force can be generated by the ideal braking force distribution. As a result, it is possible to obtain a braking force by a desired front-rear distribution while suppressing complication of the hydraulic brake device and / or cost increase.

  In the above description, in order to help the understanding of the invention, the reference numerals used in the embodiments are attached to the configuration of the invention corresponding to the embodiments in parentheses, but each constituent element of the invention is represented by the reference numerals. It is not intended to be limited to the embodiments specified.

1 is a schematic configuration diagram of a vehicle on which a vehicle braking force control device according to an embodiment is mounted. It is a flowchart showing a brake control routine. It is a figure explaining the method to distribute a target braking force to a target hydraulic braking force and a target motor braking / driving force. It is a figure explaining the method of allocating the target braking force to the target hydraulic braking force and the target motor braking / driving force when there is no regenerative capability. It is a graph showing the ideal back-and-forth distribution characteristic (a) and the actual braking distribution characteristic (b) of the hydraulic brake device.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the configuration of a vehicle 1 on which the vehicle braking / driving force control device of this embodiment is mounted.

  The vehicle 1 includes a left front wheel 10fl, a right front wheel 10fr, a left rear wheel 10rl, and a right rear wheel 10rr. The left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr are suspended from the vehicle body by suspensions (not shown).

  The vehicle 1 of this embodiment is a four-wheel drive vehicle, and includes a front wheel motor 30f as a drive source for the left front wheel 10fl and the right front wheel 10fr, and a rear wheel motor as a drive source for the left rear wheel 10rl and the right rear wheel 10rr. 30r. As the front wheel motor 30f and the rear wheel motor 30r, for example, brushless motors are used. The output torque of the front wheel motor 30f is transmitted to the propeller shaft 15f. The torque of the propeller shaft 15f is transmitted to the left front wheel 10fl and the right front wheel 10fr via the differential 16f and the drive shafts 17fl and 17fr. The output torque of the rear wheel motor 30r is transmitted to the propeller shaft 15r. The torque of the propeller shaft 15r is transmitted to the left rear wheel 10rl and the right rear wheel 10rr via the differential device 16r and the drive shafts 17rl and 17rr.

  The left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr are provided with hydraulic friction brake mechanisms (simply called friction brake mechanisms) 40fl, 40fr, 40rl, 40rr. The friction brake mechanisms 40fl, 40fr, 40rl, and 40rr are formed by brake disc rotors 41fl, 41fr, 41rl, and 41rr that rotate together with the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr, and the hydraulic pressure of the brake hydraulic fluid. A brake caliper 42fl, 42fr, 42rl, 42rr that presses a brake pad against the brake disc rotor 41fl, 41fr, 41rl, 41rr by operating a wheel cylinder (not shown) is provided.

  Regarding the configuration provided for each wheel, the sign of the left front wheel is fl, the left front wheel is fr, the left rear wheel is rr, and the right rear wheel is rl. In the description of, when it is not necessary to specify the wheel position, the last symbol is omitted. Accordingly, the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr are referred to as wheels 10, and the friction brake mechanisms 40fl, 40fr, 40rl, and 40rr are referred to as friction brake mechanisms 40. When it is necessary to distinguish between the front wheel side configuration and the rear wheel side configuration, the left front wheel 10fl and the right front wheel 10fr are referred to as front wheels 10f, and the left rear wheel 10rl and the right rear wheel 10rr are rear wheels. 10r.

  The front wheel motor 30f is connected to the front wheel motor driver 35f, and the rear wheel motor 30r is connected to the rear wheel motor driver 35r. For example, an inverter is used for each of the motor drivers 35f and 35r. The front wheel motor driver 35f converts the DC power supplied from the battery 70 into AC power and supplies the AC power to the front wheel motor 30f. The rear wheel motor driver 35r converts the DC power supplied from the battery 70 into AC power and supplies the AC power to the rear wheel motor 30r. Accordingly, the front wheel motor 30f and the rear wheel motor 30r are driven and controlled independently of each other to generate a driving torque, and a driving force independent of each other is applied to the front wheel 10f and the rear wheel 10r. In this way, supplying power to the motors 30f and 30r to generate drive torque is called powering.

  Further, the front wheel motor 30f and the rear wheel motor 30r also function as a generator. The front wheel motor 30f can generate electric power by the rotational energy of the front wheel 10f and regenerate the generated power to the battery 70 via the front wheel motor driver 35f. The rear wheel motor 30r can generate electric power using the rotational energy of the rear wheel 10r and can regenerate the generated power to the battery 70 via the rear wheel motor driver 35r. Therefore, the front wheel motor 30f and the rear wheel motor 30r are independently regeneratively controlled to generate braking torque, and to apply independent braking force to the front wheel 10f and the rear wheel 10r.

  Therefore, the battery 70 serves as a common drive power source for the two motors 30r and 30f, and serves as a common power regeneration destination.

  Hereinafter, the front wheel motor 30f and the rear wheel motor 30r are simply referred to as the motor 30 when it is not necessary to specify one of them. Similarly, the front wheel motor driver 35f and the rear wheel motor driver 35r are simply referred to as a motor driver 35 when it is not necessary to specify one of them.

  In addition, when it is not necessary to distinguish between the driving force and the braking force, they are called braking / driving force, and when it is necessary to specify the driving force, the driving force and the braking force. When it is necessary to specify, it is called a braking force.

  Each friction brake mechanism 40 is connected to a brake actuator 45. The brake actuator 45 is an actuator that controls the hydraulic pressure of the brake hydraulic oil supplied to the wheel cylinder built in each friction brake mechanism 40. The brake actuator 45 is a type that controls the hydraulic pressure of the four wheel cylinders with a common linear control valve. Since such a brake actuator 45 is well-known and will not be described in detail, for example, a hydraulic circuit that supplies a common hydraulic pressure to the wheel cylinders of the friction brake mechanisms 40, a master cylinder that pressurizes the hydraulic oil by the depression force of the brake pedal A four-wheel wheel cylinder provided in a common hydraulic circuit that includes a booster pump and an accumulator and generates high-pressure oil pressure regardless of brake pedal depression force, and a four-wheel wheel cylinder from the power oil pressure generator to the four-wheel wheel cylinder A set of linear control valves (pressure-increasing linear control valve, pressure-decreasing linear control valve) for adjusting the hydraulic pressure of the hydraulic circuit, a hydraulic sensor for detecting the hydraulic pressure of the hydraulic circuit, and the like.

  Such a brake actuator 45 of the type that commonly controls the wheel cylinder pressure of the four wheels with a set of linear control valves is described in detail in, for example, Japanese Patent Application Laid-Open No. 2013-256253. Therefore, such a known brake actuator 45 can be applied. There are also known brake actuators that can control the wheel cylinder pressure of the four wheels independently, or that can control the wheel cylinder pressure of the front wheel 10f and the rear wheel 10r independently. Since it becomes high-cost, application to this embodiment becomes unsuitable.

  The vehicle 1 includes a power management ECU 51 (hereinafter referred to as a power ECU 51), a motor ECU 52, and a brake ECU 53. The power ECU 51 is connected to the motor ECU 52 and the brake ECU 53 so as to communicate with each other. Each of the ECUs 51, 52, 53 includes a microcomputer including a CPU, a ROM, a RAM, and the like as a main part and executes various programs. “ECU” is an abbreviation for Electric Control Unit.

  The power ECU 51 is connected to an accelerator sensor 61 that detects the accelerator operation amount of the driver from an accelerator pedal depression amount (or angle, pressure, etc.) and a battery sensor 63 that detects the state of the battery 70. The battery sensor 63 outputs a detection signal indicating a state of charge (SOC) of the battery 70, a terminal voltage of the battery 70, a current flowing through the battery 70, a temperature of the battery 70, and the like.

  The brake ECU 53 is connected to a hydraulic sensor (not shown) provided in the brake actuator 45, various control valves, and a pump. The brake ECU 53 also includes a brake sensor 62 that detects the amount of brake operation by the driver from the amount of depression (or angle, pressure, etc.) of the brake pedal, and four wheel speed sensors 64 that respectively detect the wheel speeds of the four wheels. Is connected.

  Two motor drivers 35f and 35r are connected to the motor ECU 52. The motor ECU 52 is connected to a current sensor (not shown) provided in the motor drivers 35f and 35r and a rotation angle sensor (not shown) provided to the motors 30f and 30r.

  The power ECU 51 calculates the target motor driving force of the two motors 30 when the accelerator pedal is operated, receives the signal representing the target motor braking / driving force of the two motors 30 transmitted from the brake ECU 53, and the above The target motor driving force or the target motor braking / driving force is converted into the torque of the motor 30, and a command signal representing the target motor torque is transmitted to the motor ECU 52. Further, the power ECU 51 performs a process of calculating electric power that can be regenerated in the battery 70 based on the state of the battery 70, the vehicle speed, and the like, and transmitting regenerative power information that represents the calculation result to the brake ECU 53.

  The brake ECU 53 calculates the target hydraulic braking force of the front and rear wheels 10f and 10r and the target motor braking / driving force of the two motors 30 when the brake pedal is operated, and outputs a signal representing the calculated target motor braking / driving force to the power ECU 51. And processing for controlling the operation of the brake actuator 45 based on the calculated target hydraulic braking force. The brake ECU 53 calculates the vehicle speed (vehicle speed) based on the wheel speeds of the four wheels detected by the wheel speed sensor 64, and the power ECU 51 outputs vehicle speed information representing the calculated vehicle speed via a communication network (not shown). The process which transmits to several vehicle-mounted ECU containing is performed.

  The motor ECU 52 supplies a control signal (for example, a PWM control signal) to the motor drivers 35f and 35r so that the two motors 30f and 30r output the target motor torque according to the command signal commanded from the power ECU 51.

  Here, a process when the driver operates the accelerator pedal will be briefly described. When the driver performs the accelerator pedal operation, the power ECU 51 calculates the driver requested driving force based on the accelerator operation amount. The driver-requested driving force is a driving force in the vehicle front-rear direction that should be generated by the entire vehicle requested by the driver, that is, a driving force for driving (a force that increases the rotational speed of the wheels 10). The power ECU 51 stores association data such as a map for deriving the driver requested driving force from the accelerator operation amount, and calculates the driver requested driving force using the association data. For example, the driver-requested driving force is set to a value that increases as the accelerator operation amount (accelerator opening or the like) increases.

  The power ECU 51 calculates the target motor driving force of the front and rear wheels 10f and 10r obtained by distributing the driver-requested driving force to the front and rear wheels 10f and 10r at a preset distribution ratio (for example, 1/2). The driving force is converted into the target motor torque, and a drive command signal representing the target motor torque is transmitted to the motor ECU 52. Thereby, the motor ECU 52 outputs a control signal generated so that the two motors 30f and 30r generate the target motor torque in accordance with the respective target motor torques to the motor drivers 35f and 35r. Thus, the duty ratios of the switching elements of the motor drivers 35f and 35r are controlled, current corresponding to the target motor torque flows to the motors 30f and 30r, and driving force is generated on the wheels 10f and 10r.

  Next, processing when the driver operates the brake pedal will be described. As described above, the relationship between the braking force of the front wheel 10f and the braking force of the rear wheel 10r during vehicle deceleration is such that the distribution ratio of the front wheels 10f increases as the driver-requested braking force increases, as shown in FIG. It is desirable to set it to be large. On the other hand, the brake actuator 45 of this embodiment is a type that controls the hydraulic pressure of the four wheel cylinders with a common linear control valve. For this reason, as shown in FIG. 5B, the distribution ratio between the hydraulic braking force of the front wheel 10f and the hydraulic braking force of the rear wheel 10r is always constant regardless of the hydraulic pressure output from the brake actuator 45. .

  Therefore, in the present embodiment, the ideal braking force distribution characteristic shown in FIG. 5A and the actual braking force distribution characteristic shown in FIG. 5B (the distribution characteristic of the brake device including the brake actuator 45 and the friction brake mechanism 40). The motor 30 generates a braking / driving force for compensating for the difference from the above. That is, the ideal braking force distribution characteristic is obtained by the combined force of the hydraulic braking force by the friction brake mechanism 40 and the braking / driving force by the motor 30.

  FIG. 2 is a flowchart showing a brake control routine executed by the brake ECU 53. The brake ECU 53 repeatedly executes the main brake control routine at a predetermined calculation cycle while the brake pedal operation is being performed. In this explanation, parameters necessary for brake control are defined as follows. The unit in parentheses represents a unit.

Vehicle weight: W (N)
Front axle weight: Wf (N)
Rear axle weight: Wr (N)
Wheelbase: L (m)
Vehicle center of gravity height: H (m)
Front wheel braking force distribution ratio: x (-)
Regenerative power: P (w)
Vehicle speed: V (m / s)

  When the brake control routine is activated, the brake ECU 53 detects the amount of brake operation based on the sensor signal output from the brake sensor 62 in step S11. Subsequently, in step S12, the brake ECU 53 calculates a required deceleration α of the vehicle based on the brake operation amount. The required deceleration α is a value represented by the ratio of the required deceleration acceleration to the gravitational acceleration (deceleration acceleration / gravity acceleration). The brake ECU 53 stores association data for deriving the requested deceleration rate α (−) from the brake operation amount, and calculates the requested deceleration rate α based on the association data. For example, the required deceleration α is set to a value that increases as the brake operation amount increases.

Subsequently, in step S13, the brake ECU 53 calculates the target braking force Ff (N) of the front wheel 10f and the target braking force Fr (N) of the rear wheel 10r by the following equations.
Ff = α (Wf + α · W · H / L)
Fr = α (Wr−α · W · H / L)

Subsequently, the brake ECU 53 calculates a hydraulic braking deceleration rate α ′ (−) by the following equation in step S14.
α ′ = α−P / (W · V)
Here, the hydraulic braking deceleration α ′ represents a deceleration obtained by subtracting the deceleration obtained by the maximum braking force that can be generated by power regeneration to the battery 70 from the required deceleration α. That is, it represents the deceleration generated by the hydraulic braking force obtained by subtracting the regenerative braking force obtained when the battery 70 is regenerated as much as possible from the total target braking force of the four wheels. The electric power that can be regenerated to the battery 70 is transmitted from the power ECU 51 to the brake ECU 53 in real time as regenerative power information. The brake ECU 53 obtains the regenerative power P (w) based on the regenerative power information transmitted from the power ECU 51, and calculates the hydraulic braking deceleration α ′.

Subsequently, in step S15, the brake ECU 53 calculates the target hydraulic braking force Fpf (N) of the front wheel 10f and the target hydraulic braking force Fpr (N) of the rear wheel 10r by the following equations.
Fpf = W (α−P / (W · V) x = (W · α−P / V) x
Fpr = W ([alpha] -P / (W * V) (1-x) = (W * [alpha] -P / V) (1-x)
Here, x represents the front wheel braking force distribution ratio determined by the characteristics of the friction brake mechanisms 40f, 40r of the front and rear wheels 10f, 10r. Therefore, (1-x) represents the rear wheel braking force distribution ratio determined by the characteristics of the friction brake mechanisms 40f and 40r of the front and rear wheels 10f and 10r.

Subsequently, in step S16, the brake ECU 53 calculates the target motor braking / driving force Fmf (N) of the front wheel 10f and the target motor braking / driving force Fmr (N) of the rear wheel 10r by the following equations.
Fmf = Ff−Fpf = α (Wf + α · W · H / L) − (W · α−P / V) x
Fmr = Fr−Fpr = α (Wr−α · W · H / L) − (W · α−P / V) (1−x)

  The target motor braking / driving force Fmf of the front wheel 10f and the target motor braking / driving force Fmr of the rear wheel 10r may work as regenerative braking force or may act as driving force. Of course, the combined force of the target motor braking / driving force Fmf and the target motor braking / driving force Fmr serves as the maximum regenerative braking force that can regenerate power in the battery 70.

  Subsequently, the brake ECU 53 transmits signals representing the target motor braking / driving forces Fmf and Fmr for the front and rear wheels 10f and 10r to the power ECU 51 in step S17. As a result, the power ECU 51 converts the target motor braking / driving forces Fmf, Fmr for the front and rear wheels 10f, 10r into the target motor torque for driving the motors 30f, 30r, and generates a braking / driving command signal representing the target motor torque. Send to. Thereby, motor ECU52 outputs a drive signal to motor drivers 35f and 35r according to target motor torque. When the target motor torque represents the drive torque, the motor 30 is power-running and a current flows from the motor driver 35 to the motor 30. When the target motor torque represents the braking torque, the motor 30 is regeneratively controlled and a current flows from the motor 30 to the battery 70 via the motor driver 35. Thus, an independent braking / driving force is generated for each of the front and rear wheels 10f, 10r.

  Subsequently, the brake ECU 53 controls the operation of the brake actuator 45 based on the target hydraulic braking forces Fpf and Fpr in step S18. Since the ratio between the target hydraulic braking force Fpf of the front wheel 10f and the target hydraulic braking force Fpr of the rear wheel 10r has a certain relationship (x: (1-x)), the brake ECU 53 can control either one of the target hydraulic braking forces Fpf. The target control hydraulic pressure of the wheel cylinder is set based on the power Fpf (Fpr). The brake ECU 53 stores association data such as a map for deriving the target control oil pressure from the target hydraulic braking force Fpf (Fpr), and calculates the target control oil pressure using this association data. The target control hydraulic pressure is set to a value that increases as the target hydraulic braking force Fpf (Fpr) increases.

  The brake ECU 53 controls energization of the linear control valve so that the hydraulic pressure of the four wheel cylinders detected by the hydraulic pressure sensor (the hydraulic pressure common to the four wheels) follows the target control hydraulic pressure. As a result, the four-wheel friction brake mechanism 40 is actuated to brake each wheel 10 with a frictional force. The target control hydraulic pressure may be calculated from the hydraulic braking deceleration rate α ′. In this case, the brake ECU 53 stores association data in which the relationship between the hydraulic braking deceleration α ′ and the target control oil pressure is set, and calculates the target control oil pressure using this association data.

  As a result, a combined braking force (Fpf + Fmf) obtained by combining the target hydraulic braking force Fpf and the target motor braking / driving force Fmf is generated on the front wheel 10f, and the target hydraulic braking force Fpr and the target motor braking / driving are generated on the rear wheel 10r. A combined braking force (Fpr + Fmr) combined with the force Fmr is generated.

  The brake ECU 53 once ends the brake control routine when the process of step S18 is performed. Then, the brake control routine is repeated at a predetermined calculation cycle.

  Here, the relationship between the hydraulic braking force and the regenerative braking force set by the brake control routine will be described with reference to FIG. In FIG. 3, an ideal characteristic line L * represents an ideal braking force distribution characteristic that represents an ideal distribution relationship between the braking force of the front wheel 10f and the braking force of the rear wheel 10r during vehicle deceleration. This ideal braking force distribution characteristic represents the relationship between the target braking force Ff and the target braking force Fr of the front and rear wheels 10f and 10r calculated by the brake ECU 53 in step S13, and as the required deceleration α increases (the front and rear wheels 10f). , 10r as the target braking force increases), the front / rear distribution ratio (Ff / (Ff + Fr)) of the front wheels 10f increases. Therefore, the target braking forces Ff and Fr of the front and rear wheels 10f and 10r calculated by the brake ECU 53 in step S13 are in line with this ideal braking force distribution characteristic and correspond to the ideal target braking force of the present invention.

  On the other hand, in FIG. 3, the hydraulic characteristic line Lp represents the front-rear distribution characteristic of the hydraulic braking force. In this embodiment, since the wheel cylinder hydraulic pressure of each wheel is controlled to a common hydraulic pressure, the front-rear distribution characteristics of the hydraulic braking force are determined by the characteristics of the friction brake devices 40f, 40r in the front and rear wheels 10f, 10r, It becomes a certain front-back distribution ratio.

  The broken line shown in FIG. 3 represents a constant deceleration line. Here, as an example, four equal deceleration lines L1a, L1b, L2a, and L2b are shown. When the braking force specified at an arbitrary point on the constant deceleration line is generated by the front and rear wheels 10f and 10r, the same deceleration can be obtained. Therefore, if the required deceleration α (target braking force) is determined, the target braking force is increased or decreased at the ideal point represented by the intersection of the constant deceleration line and the ideal characteristic line L * corresponding to the required deceleration α. If distributed to the wheels 10f, 10r, the front / rear distribution along the ideal braking force characteristics becomes possible.

  For example, as shown in FIG. 3, if the constant deceleration line L1a set corresponding to the required deceleration α is determined, the ideal point P1 represented by the intersection of the constant deceleration line L1a and the ideal characteristic line L *. By setting the target braking force (Ff1, Fr1) by the ideal braking force distribution becomes possible.

  When the target braking force is generated only by the regenerative braking force, if the regenerative braking torque of the front wheel motor 30f and the rear wheel motor 30r is controlled independently, the regenerative control is performed at the front / rear distribution ratio represented by the ideal point P1. Power can be generated. However, since the regenerative braking force that can be generated is limited by the vehicle speed, the state of the battery 70, and the like, a hydraulic braking force may be required to obtain the required deceleration α.

  Therefore, in the present embodiment, the hydraulic braking force is generated by the friction brake mechanism 40 so that the target braking force (required deceleration rate α) can be obtained while generating the maximum regenerative braking force that can be regenerated by the two motors 30. Let In this case, the target motor braking / driving forces of the front and rear wheels 10f and 10r are set so that the braking force distribution of the front and rear wheels 10f and 10r has an ideal braking force distribution characteristic. For example, consider the case where the target braking force (Ff1, Fr1) is set at the ideal point P1 in FIG. As shown in FIG. 3, a constant deceleration line L1b shifted from the constant deceleration line L1a by the deceleration obtained by the maximum braking force that can be generated by power regeneration to the battery 70 can be drawn. The range of the constant deceleration line L1b and the constant deceleration line L1a represents the regenerative range (deceleration adjustment range by regenerative braking force).

  When the regenerative braking force is generated to the maximum by the two motors 30, the target hydraulic braking force Fpf1 of the front wheel 10f and the rear wheel are determined by the hydraulic point Pp1 that is the intersection of the constant deceleration line L1b and the hydraulic characteristic line Lp. The target hydraulic braking force Fpr1 of 10r is set, and the difference (Ff1-Fpf1, Fr1-Fpr1) between the ideal point P1 and the hydraulic point Pp1 is set as the target motor braking / driving force Fmf1 of the front wheels 10f and the target motor braking of the rear wheels 10r. If the driving force Fmr1 is set, the front and rear wheels 10f and 10r can be braked at the ideal point P1. Therefore, the target motor braking / driving force Fmf1 of the front wheel 10f is represented by Fmf1 = (Ff1-Fpf1), and the target motor braking / driving force Fmr1 of the rear wheel 10r is represented by Fmr1 = (Fr1-Fpr1). In this case, the target motor braking / driving force Fmf1 and the target motor braking / driving force Fmr1 are both forces acting in the braking direction.

  As another example, consider a case where the target braking force (Ff2, Fr2) is set at the ideal point P2. As shown in FIG. 3, the constant deceleration line L2b shifted from the constant deceleration line L2a by the deceleration obtained by the maximum braking force that can be generated by power regeneration to the battery 70 can be drawn. The range of the constant deceleration line L2b and the constant deceleration line L2a represents the regenerative range.

  In this case, the target hydraulic braking force Fpf2 of the front wheel 10f and the target hydraulic braking force Fpr2 of the rear wheel 10r are set by the hydraulic point Pp2 that is the intersection of the constant deceleration line L2b and the hydraulic characteristic line Lp, and the ideal point P2 And the hydraulic point Pp2 (Ff2-Fpf2, Fr2-Fpr2) are set to the target motor braking / driving force Fmf2 of the front wheel 10f and the target motor braking / driving force Fmr2 of the rear wheel 10r, the front and rear wheels at the ideal point P2 10f and 10r can be braked. Accordingly, the target motor braking / driving force Fmf2 of the front wheel 10f is represented by Fmf2 = (Ff2-Fpf2), and the target motor braking / driving force Fmr2 of the rear wheel 10r is represented by Fmr2 = (Fr2-Fpr2). In this case, the target motor braking / driving force Fmf2 of the front wheel 10f is a force acting in the braking direction, but the target motor braking / driving force Fmr2 of the rear wheel 10r is a force acting in the driving direction.

  The same can be considered when the battery 70 is in a state where power cannot be regenerated (regenerative power P = 0). For example, as shown in FIG. 4, when the target braking force (Ff3, Fr3) is set at the ideal point P3, the hydraulic point that is the intersection of the constant deceleration line L3 and the hydraulic characteristic line Lp passing through the ideal point P3. The target hydraulic braking force Fpf3 of the front wheel 10f and the target hydraulic braking force Fpr3 of the rear wheel 10r are set by Pp3, and the difference (Ff3-Fpf3, Fr3-Fpr3) between the ideal point P3 and the hydraulic point Pp3 is set as the front wheel 10f. If the target motor braking / driving force Fmf3 and the rear motor 10r target motor braking / driving force Fmr3 are set, the front and rear wheels 10f, 10r can be braked at the ideal point P3. In this case, the target motor braking / driving force Fmr3 of the rear wheel 10r is a force acting in the driving direction.

  In the case where the braking force is generated at the ideal point P4 (Ff4, Fr4) in FIG. 4, the front wheel is driven by the hydraulic point Pp4 that is the intersection of the constant deceleration line L4 passing through the ideal point P4 and the hydraulic characteristic line Lp. The target hydraulic braking force Fpf4 of 10f and the target hydraulic braking force Fpr4 of the rear wheel 10r are set, and the difference (Ff4-Fpf4, Fr4-Fpr4) between the ideal point P4 and the hydraulic point Pp4 is set as the target motor control of the front wheel 10f. If the driving force Fmf4 and the target motor braking / driving force Fmr4 for the rear wheel 10r are set, the front and rear wheels 10f and 10r can be braked at the ideal point P4. In this case, the target motor braking / driving force Fmr4 of the rear wheel 10r is a force acting in the driving direction.

  The brake control routine shown in FIG. 2 represents a process for setting the target braking force (Fpf, Fpr, Fmf, Fmr) of the front and rear wheels 10f, 10r based on such a principle by an arithmetic expression. The target hydraulic braking forces Fpf1, Fpf2, Fpf3, and Fpf4 are set as the values of the target hydraulic braking forces Fpf of the front wheels 10f in step S15. The target hydraulic braking forces Fpr1, Fpr2, Fpr3, and Fpr4 is set as the value of the target hydraulic braking force Fpr of the rear wheel 10r in step S15. The target motor braking / driving forces Fmf1, Fmf2, Fmf3, and Fmf4 are set as values of the target motor braking / driving force Fmf of the front wheel 10f in step S16, and the target motor braking / driving forces Fmr1, Fmr2 described above. , Fmr3, Fmr4 are set as values of the target motor braking / driving force Fmr of the rear wheel 10r in step S16.

  Thereby, an ideal braking force distribution characteristic is obtained by a combined force of the hydraulic braking force by the friction brake mechanism 40 and the braking / driving force by the motor 30.

  According to the vehicle braking force control apparatus of the present embodiment described above, the hydraulic braking deceleration obtained by subtracting the deceleration obtained by the maximum braking force that can be generated by power regeneration to the battery 70 from the required deceleration α. Target hydraulic braking forces Fpf and Fpr necessary for decelerating the vehicle at α ′ are set. That is, when the maximum braking force that can be generated by power regeneration to the battery 70 is generated by the motors 30f and 30r, it is necessary to be generated by the hydraulic brake device in order to decelerate the vehicle at the required deceleration α. The target hydraulic braking forces Fpf and Fpr are set by distributing the braking force at a constant front / rear distribution ratio.

  Further, the target motor braking / driving forces Fmf and Fmr generated by the motors 30f and 30r based on the difference between the target braking forces Ff and Fr set according to the ideal braking force distribution characteristic and the target hydraulic braking forces Fpf and Fpr are obtained. Is set. Therefore, even in a vehicle 1 equipped with a hydraulic brake device (brake actuator 45, friction brake mechanism 40) in which the front-rear distribution characteristics of the braking force cannot be adjusted, braking / driving generated by the motors 30f, 30r in the front and rear wheels 10f, 10r. By controlling the force, the braking force can be generated with the ideal braking force distribution. As a result, it is possible to obtain a braking force by a desired front-rear distribution while suppressing complication of the hydraulic brake device and / or cost increase.

  The vehicular braking force control apparatus according to the present embodiment has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in this embodiment, the present invention is applied to a vehicle of a type including two motors including a front wheel motor 30f that drives the left and right front wheels 10f in common and a motor 30r that drives the left and right rear wheels 10r in common. The present invention can also be applied to a vehicle in which left and right front and rear wheels are independently driven by four motors. In this case, an in-wheel motor type vehicle in which a motor is incorporated in the wheel 10 may be used. Further, the present invention can also be applied to a vehicle having a total of three motors including a motor that drives one of the front and rear wheels 10f and 10r in common and two motors that drive the other wheel independently.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 10 ... Wheel, 10f ... Front wheel, 10r ... Rear wheel, 30 ... Motor, 30f ... Front wheel motor, 30r ... Rear wheel motor, 35 ... Motor driver, 40 ... Friction brake mechanism, 45 ... Brake actuator, 51 ... Power management ECU 52 ... motor ECU 53 ... brake ECU 61 ... accelerator sensor 62 ... brake sensor 63 ... battery sensor 70 ... battery L * ... ideal characteristic line Lp ... hydraulic characteristic line

Claims (1)

A hydraulic brake device that operates by the hydraulic pressure of the brake hydraulic oil and generates a hydraulic braking force at a constant front-rear distribution ratio on the front and rear wheels;
A motor that generates a braking / driving force on the front and rear wheels by transmitting at least the front and rear wheels independent driving torque and regenerative braking torque to the front and rear wheels;
A battery serving as a driving power source and a power regeneration destination of the motor;
Based on the required deceleration required for decelerating the vehicle and the preset ideal braking force distribution characteristic in which the front-rear distribution ratio on the front wheel side increases as the required deceleration increases, the ideal target control of the front and rear wheels. Ideal target braking force setting means for setting power;
When the maximum braking force that can be generated by power regeneration to the battery is generated by the motor, the braking force that needs to be generated by the hydraulic brake device to decelerate the vehicle at the required deceleration Target hydraulic braking force setting means for setting the target hydraulic braking force of the front and rear wheels by allocating at the constant front / rear distribution ratio;
A target motor braking / driving force setting means for setting a target motor braking / driving force of the front and rear wheels generated by the motor based on a difference between the ideal target braking force and the target hydraulic braking force;
Hydraulic control means for controlling the operation of the hydraulic brake device based on the target hydraulic braking force;
A vehicle braking force control device comprising: motor control means for controlling the operation of the motor based on the target motor braking / driving force.

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