JP6020279B2 - Vehicle braking force control device - Google Patents

Description

  The present invention relates to a vehicle braking force control device that controls the braking force of a vehicle, and more particularly to a vehicle braking force control device that cooperates an electric force generation mechanism and a braking force generation mechanism during braking.

  In recent years, electric vehicles (EV), hybrid vehicles (HV), fuel cell vehicles (FCEV), etc. have been developed as vehicles having an electric force generation mechanism (for example, an electric motor) that generates driving force or braking force at least on wheels. As one form of such a vehicle, an electric force generation mechanism is arranged in or near the wheel of the wheel, and the wheel is directly driven by this electric force generation mechanism. Wheel motor type vehicles have been proposed.

  In such an in-wheel motor vehicle, an electric force generation mechanism provided for each wheel (drive wheel) is individually controlled to rotate, that is, each electric force generation mechanism is individually driven and controlled (power running control). Alternatively, by performing regenerative control, the driving torque or braking torque applied to each driving wheel can be individually controlled, and the driving force and braking force of the vehicle can be appropriately controlled according to the running state. Then, by utilizing the fact that the driving torque or braking torque to be applied to each driving wheel can be individually controlled in this way, in particular, with regard to braking, an electric force generating mechanism that is operated by regenerative control as a braking device is controlled. For example, it has been proposed to control a braking torque (braking force) generated on each wheel by cooperating with a mechanical brake device operated by, for example, hydraulic pressure as a power generation mechanism.

  For example, in the vehicle behavior control device disclosed in Patent Document 1 below, the required torque to be generated for each wheel is calculated based on the vehicle behavior, and the calculated torque required for each wheel is frictional. A uniform torque value for each wheel is set as the friction braking torque generated on the wheels by the braking means, and an independent torque value is set as the driving torque or regenerative braking torque generated for each wheel for each electric motor of each wheel. It has become. In setting the torque value, the remaining battery level of the in-vehicle battery is measured, and the friction braking torque set by the friction braking means and the driving torque or regenerative braking set by the electric motor are determined according to the measured remaining ionization level. The distribution with torque is changed.

  Further, for example, in the vehicle braking force control device described in Patent Document 2 below, when each wheel has a tendency to lock, if the battery capacity of the battery is small, the in-wheel motor provided on the left and right front wheels is regenerated. A motor braking torque is generated by being operated, and an in-wheel motor provided on the left and right rear wheels is operated in a power running state to generate a motor driving torque. Further, in this conventional vehicle braking force control device, when each wheel has a tendency to lock, if the battery capacity of the battery is large, the in-wheel motors provided on the left and right front wheels are operated according to the power running state to generate motor driving torque. In addition, the in-wheel motor provided on the left and right rear wheels is operated in a regenerative state to generate motor braking torque.

JP 2009-143432 A JP 2012-70470 A

  By the way, in the conventional vehicle behavior control device disclosed in Patent Document 1 and the conventional vehicle braking force control device disclosed in Patent Document 2, depending on the remaining battery capacity of the in-vehicle battery and the battery capacity of the battery. Control of electric motors and in-wheel motors. For this reason, in the conventional vehicle behavior control device and the conventional vehicle braking force control device, it is necessary to check the remaining battery level of the in-vehicle battery and the battery capacity of the battery when executing the control.

  Here, the remaining battery capacity and the battery capacity may vary depending on, for example, the aging of the battery, the battery temperature, and the like, and the remaining battery capacity and the battery capacity may not always be obtained accurately and reliably. . Therefore, regenerative braking using an electric motor or an in-wheel motor (electric power generation mechanism) cannot be used due to factors such as battery state (remaining battery level or battery capacity) that are not directly related to braking. When a situation arises, the brake must be braked only by friction braking means (braking force generating mechanism). In such a situation, smooth and stable braking may be impaired, and the driver may feel uncomfortable.

  Considering the braking performance, the friction braking means (braking force generation mechanism) is omitted, and regenerative braking only with an electric motor or in-wheel motor (electric force generation mechanism) enables more precise braking force control. It is said that the braking distance is shortened and ideal. However, it is difficult to always brake the vehicle with only regenerative braking, as long as regenerative braking with an electric motor or an in-wheel motor (electric power generation mechanism) cannot be used due to the uncertain factors described above. In addition, it is necessary to brake the vehicle in cooperation with an electric motor or an in-wheel motor (electric force generation mechanism) and a friction braking means (braking force generation mechanism).

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide mechanical control by the braking force generation mechanism so that braking using the electric force generation mechanism is always possible during vehicle braking. An object of the present invention is to provide a vehicle braking force control device that appropriately sets the magnitude of power.

  In order to achieve the above object, a vehicle braking control apparatus of the present invention includes an electric force generation mechanism, a power storage unit, a braking force generation mechanism, a braking operation unit, and a braking control unit. The electric force generating mechanism generates an electromagnetic driving force or an electromagnetic braking force on a vehicle wheel. The power storage means is electrically connected to the electric power generation mechanism. The braking force generation mechanism generates a mechanical braking force on the wheels rotated by at least the electromagnetic driving force generated by the electric force generation mechanism. The braking operation means is operated by a driver to brake the vehicle. The braking control means generates the electromagnetic braking force generated by operating the electric force generating mechanism in a regenerative state or the electric force generating mechanism operated in a power running state in response to an operation of the braking operation means. The electromagnetic driving force and the mechanical braking force by the braking force generation mechanism are controlled to generate a braking force for the wheels.

One of the characteristics of the braking force control device for a vehicle according to the present invention is that the braking control means operates the electric force generation mechanism in the regenerative state to generate the electromagnetic braking force. The amount of electric energy flowing into the power storage means from the force generation mechanism and the generation of the electric force from the power storage means when the electric power generation mechanism is operated in the power running state to generate the electromagnetic driving force. The amount of electrical energy flowing out to the mechanism is accumulated and accumulated, and the target braking force to be generated on the wheel is determined according to the road surface condition where the vehicle travels, and this target braking force is generated on the wheel. when, which controls the magnitude of the mechanical braking force by the braking force generating mechanism while maintaining a balance between the outflow amount of electrical energy and the inflow amount of electric energy Further, the brake control means increases the magnitude of the mechanical braking force by the braking force generation mechanism when the magnitude of the inflow electric energy amount is equal to or greater than the magnitude of the outflow electric energy amount, The operation according to the power running state of the electric force generation mechanism is increased, or the electromagnetic braking force due to the regenerative state of the electric force generation mechanism is decreased, and the magnitude of the inflow electric energy amount is determined as the outflow electric energy. Whether the magnitude of the mechanical braking force by the braking force generation mechanism is decreased and the electromagnetic braking force by the regeneration state of the electric force generation mechanism is increased when the amount of energy is less than the amount of energy Alternatively, the operation by the power running state of the electric force generation mechanism is reduced . Here, more specifically, when the braking control means determines whether or not the wheels tend to lock based on a road surface condition where the vehicle travels, and determines that the wheels tend to lock The magnitude of the mechanical braking force by the braking force generation mechanism can be controlled while maintaining a balance between the inflow electric energy amount and the outflow electric energy amount.

  According to these, the braking control means integrates the inflow electric energy amount and the outflow electric energy amount by the electric force generation mechanism at the time of braking control (particularly when the wheel tends to lock with braking). Accumulation of the mechanical braking force by the braking force generation mechanism so that the inflow electric energy amount and the outflow electric energy amount are balanced, that is, the electric energy balance is almost zero. The target braking force can be generated on the wheel by controlling the size. That is, the braking control means, based on the accumulated electric energy balance history, if the magnitude of the inflow electric energy is greater than or equal to the magnitude of the outflow electric energy, in other words, the regenerative quantity that is the inflow electric energy. When electric power is stored in the power storage means, the electric force generation mechanism is operated in the power running state (or the electric force generation mechanism is operated in the regenerative state) in order to consume this inflow electric energy amount (regenerative electric power). In other words, increase the amount of electrical energy that flows out. In this case, the braking control means is configured such that the magnitude of the mechanical braking force generated by the braking force generation mechanism in order to ensure the target braking force as the electric force generation mechanism generates an electromagnetic driving force. Increase. As a result, the amount of inflow electric energy (regenerative power) can be suppressed from being supplied to the power storage means and stored, and as a result, it is always possible during braking control regardless of the power storage state in the power storage means. It is possible to maintain a state in which the electric force generation mechanism can be operated in the regenerative state.

  Further, the braking control means is based on the accumulated electric energy balance history, and when the magnitude of the inflow electric energy is less than the magnitude of the outflow electric energy, in other words, the electric energy in the power storage means ( When the amount of stored electricity decreases, it is possible to positively operate the electric power generation mechanism in the regenerative state (or decrease the operation of the electric power generation mechanism in the power running state). In this case, the braking control means is configured such that the magnitude of the mechanical braking force generated by the braking force generation mechanism in order to ensure the target braking force as the electric force generation mechanism generates electromagnetic braking force. Decrease. Thus, more precise braking force control can be performed using the electromagnetic braking force generated by the electric force generation mechanism. Therefore, smooth and stable braking is possible, and the driver does not feel uncomfortable.

  Further, in these cases, the braking control means increases the magnitude of the mechanical braking force by the braking force generation mechanism in advance when the inflow electric energy amount can be increased. The generating mechanism can be operated mainly in the power running state. In this case, the situation where the amount of inflow electric energy can increase is at least a situation where the distance to the front obstacle existing in front of the vehicle decreases as the vehicle travels, and the vehicle travels as the vehicle travels. One of a situation where the vehicle speed of the vehicle becomes small, a situation where the operating speed of the braking operation means by the driver increases, a situation where the target braking force is large, and a situation where the rate of change of the target braking force is large That is, a situation with a high degree of urgency can be achieved. Further, in this case, the braking control means is configured to determine the distance to the front obstacle, the vehicle speed of the vehicle, the operation speed of the braking operation means, the magnitude of the target braking force, and the rate of change of the target braking force. A ratio between the mechanical braking force by the braking force generation mechanism and the electromagnetic braking force or the electromagnetic driving force by the electric force generation mechanism is determined by a function using at least one of them. be able to.

  According to these, the electric force generation mechanism is operated in a regenerative state to generate an electromagnetic braking force, and in a situation where precise braking control is required, that is, in a highly urgent situation. , Increasing the magnitude of mechanical braking force by the braking force generation mechanism in advance to operate the electric force generation mechanism in the power running state, in other words, increasing the amount of electrical energy flowing out in advance to reduce the amount of electrical energy in the power storage means In addition, it is possible to prepare for generation of electromagnetic braking force by the electric force generation mechanism. As a result, in a highly urgent situation, it is possible to perform more precise braking force control by reliably using the electromagnetic braking force by the electric force generation mechanism.

  Further, in these cases, the braking control means may maintain the balance between the inflow electric energy amount and the outflow electric energy amount for a plurality of two or more wheels while maintaining the mechanical braking force by the braking force generation mechanism. Can be controlled. In this case, the braking control means increases the operation of the electric power generation mechanism corresponding to some of the plurality of wheels according to the regenerative state and the other part of the plurality of wheels. The mechanical force generation mechanism corresponding to the wheel of the vehicle is increased in operation according to the power running state to maintain the balance between the inflow electric energy amount and the outflow electric energy amount, and the mechanical control by the braking force generation mechanism. The magnitude of power can be controlled.

  According to these, it becomes possible to use the average value of the inflow electric energy amount and the outflow electric energy amount in a plurality of wheels, and the error of the balance between the inflow electric energy amount and the outflow electric energy amount can be reduced. The fluctuation (change) of the balance can be suppressed satisfactorily. As a result, fluctuations (changes) in the magnitude of the mechanical braking force by the braking force generation mechanism can be satisfactorily suppressed.

1 is a schematic diagram schematically showing a configuration of a vehicle to which a braking force control device for a vehicle according to the present invention can be applied. FIG. 2 is a circuit diagram of a three-phase inverter circuit in the inverter of FIG. 1. It is a flowchart of the eABS control program performed by the electronic control unit of FIG. It is a graph which shows the relationship between the depression force of a brake pedal, and required braking force. It is a graph which shows the relationship between a slip ratio and the friction coefficient of a road surface. 3 is a flowchart of an electrical energy balance management program executed by the electronic control unit of FIG. 1 according to the first embodiment of the present invention. It is a figure for demonstrating the action | operation of the in-wheel motor and friction brake mechanism accompanying execution of an electrical energy balance management program. It is a flowchart of the braking force control program which concerns on 2nd Embodiment of this invention and is performed by the electronic control unit of FIG.

a. First Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the configuration of a vehicle Ve on which the vehicle braking force control apparatus according to each embodiment can be mounted.

  The vehicle Ve includes left and right front wheels 11 and 12 and left and right rear wheels 13 and 14. The motors 15 and 16 are incorporated in the left and right front wheels 11 and 12, and the motors 17 and 18 are incorporated in the left and right rear wheels 13 and 14, respectively. The front wheels 11 and 12 and the left and right rear wheels 13 and 14 are connected so as to be able to transmit power. That is, the electric motors 15 to 18 are so-called in-wheel motors 15 to 18 and are disposed under the spring of the vehicle Ve together with the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14. Accordingly, the driving torque and the braking force generated on the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14 are independently controlled by controlling the motor torques of the in-wheel motors 15 to 18 independently. Be able to.

  Each of these in-wheel motors 15-18 is comprised by the three-phase alternating current synchronous motor, for example. And each in-wheel motor 15-18 converts the direct-current power of the electrical storage apparatus 20 which uses a battery as main component parts into alternating current power via the inverter 19, and the alternating current power is supplied. . Thereby, each in-wheel motor 15-18 is drive-controlled (namely, power running control), and provides the motor drive torque as an electromagnetic drive force with respect to the left-and-right front wheels 11 and 12 and the right-and-left rear wheels 13 and 14. To do.

  The in-wheel motors 15 to 18 can perform regenerative braking using the rotational energy of the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14. Thereby, at the time of regeneration and power generation of each in-wheel motor 15-18, the rotational (kinetic) energy of the left and right front wheels 11, 12 and the left and right rear wheels 13, 14 is converted into electric energy by each in-wheel motor 15-18. The converted electric energy, that is, regenerative power is stored in the power storage device 20 via the inverter 19. At this time, the in-wheel motors 15 to 18 apply motor braking torque as electromagnetic braking force based on regenerative power generation to the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14.

  Here, the inverter 19 constitutes a three-phase inverter circuit. As shown in FIG. 2, the inverters 19 are respectively connected to the electromagnetic coils CL1, CL2, and CL3 of the in-wheel motors 15 to 18 that are star-connected (Y-connected). Corresponding switching elements SW11, SW12, SW21, SW22, SW31, SW32 are provided. The switching elements SW11, SW12, SW21, SW22, SW31, and SW32 correspond to the switching elements SW11, SW21, and SW31 on the high side (high potential side) and the switching elements SW12, SW22, and SW32 on the low side (low potential side), respectively. In addition, each of the in-wheel motors 15 to 18 corresponds to the three phases, ie, the U phase, the V phase, and the W phase, and is configured by a MOSFET, for example. The inverter 19 (more specifically, a three-phase inverter circuit) is provided with a current sensor for detecting a current flowing in each in-wheel motor in each phase.

  The switching elements SW11, SW12, SW21, SW22, SW31, and SW32 are on / off controlled by a signal from an electronic control unit 26 described later. Therefore, in the inverter 19, for example, by controlling the pulse width of the switching elements 11, SW12, SW21, SW22, SW31, and SW32 (PWM control), the amount of current from the power storage device 20 to the in-wheel motors 15 to 18 A current amount of regenerative power from the in-wheel motors 15 to 18 to the power storage device 20 is controlled. Thereby, each in-wheel motor 15-18 is drive-controlled (namely, power running control), gives motor drive torque Tmc mentioned later to right-and-left front wheels 11 and 12, and right-and-left rear wheels 13 and 14, and is regeneratively controlled. Then, a motor braking torque Tmr described later is applied to the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14.

  1 again, the vehicle Ve is provided with friction brake mechanisms 21, 22, 23, 24 between the wheels 11-14 and the corresponding in-wheel motors 15-18, respectively. It has been. Each of the friction brake mechanisms 21 to 24 is a known braking device such as a disc brake or a drum brake, for example, and friction as a mechanical braking force due to friction with respect to the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14. Apply braking force independently. These friction brake mechanisms 21 to 24 are provided with right and left front wheels 11 and 12 and hydraulic pressure (hydraulic pressure) fed from a master cylinder (not shown) due to depression of a brake pedal B as braking operation means. The brake actuator 25 is connected to a brake caliper piston or brake shoe (both not shown) that generates a braking force on the left and right rear wheels 13 and 14.

  The inverter 19 and the brake actuator 25 are configured so that the in-wheel motors 15 to 18 are rotated (more specifically, the regenerative state or the power running state) and the friction brake mechanisms 21 to 24 are operated (more specifically, the braking state or The electronic control unit 26 is controlled to control the brake release state. Therefore, each in-wheel motor 15-18, the inverter 19, and the electrical storage apparatus 20 comprise the electric power generation mechanism of this invention, the friction brake mechanisms 21-24 and the brake actuator 25 comprise the braking force generation mechanism of this invention, The electronic control unit 26 constitutes the braking control means of the present invention.

  The electronic control unit 26 includes a microcomputer including a CPU, a ROM, a nonvolatile RAM, and the like as main components. The electronic control unit 26 executes various programs including an eABS control program, which will be described later, and operates the inverter 19 and the brake actuator 25. In other words, the operation of the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24 is controlled. For this reason, the electronic control unit 26 detects the brake sensor 27 that detects the depression force P of the brake pedal B by the driver and the wheel speeds Vwi (i = fl, fr, rl, rr) of the wheels 11 to 14. Signals from various sensors including a wheel speed sensor 28i (i = fl, fr, rl, rr) are input.

  In this way, at least the brake sensor 27 and the wheel speed sensor 28i (i = fl, fr, rl, rr) are connected to the electronic control unit 26 and each signal is input, whereby the electronic control unit 26 Can operate the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24 to control the running state of the vehicle Ve, more specifically, the braking state of the vehicle Ve. Hereinafter, the braking state of the vehicle Ve by the electronic control unit 26, that is, the braking force control generated for each of the wheels 11 to 14 will be described in detail.

  When the brake pedal B is depressed by the driver and the depression force P represented by the signal input from the brake sensor 27 is increased, the electronic control unit 26 executes the eABS control program shown in FIG. The braking force generated with respect to the wheels 11 to 14 is controlled. That is, the electronic control unit 26 (more specifically, the CPU) starts execution of the eABS control program in step S10, and acquires current vehicle state information in the traveling vehicle Ve in subsequent step S11.

  More specifically, the electronic control unit 26 is obtained from the depression force P of the brake pedal B by the driver and the wheel speed sensor 28i (i = fl, fr, rl, rr) represented by the signal input from the brake sensor 27. The wheel speed Vwi (i = fl, fr, rl, rr) of each wheel 11-14 represented by the input signal is acquired as vehicle state information. And the electronic control unit 26 will progress to step S12, if the present vehicle state information is acquired.

  In step S12, the electronic control unit 26 uses the braking force F0 (for braking the vehicle Ve using the depression force P of the brake pedal B among the current vehicle state information acquired in step S11). Hereinafter, the required braking force F0 is calculated) and the braking force (braking torque) of each of the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24 for generating the required braking force F0 is calculated. The distribution (hereinafter, this distribution is referred to as basic braking force distribution) is determined. Hereinafter, this basic braking force distribution will be specifically described.

  First, as shown in FIG. 4, the electronic control unit 26 changes the required braking force F0 that changes monotonously with respect to the change in the stepping force P acquired as the vehicle state information in step S11, for example, the change in the stepping force P. The required braking force F0 that changes proportionally with respect to is calculated. Then, in order to generate the calculated required braking force F0, the electronic control unit 26 operates the in-wheel motors 15 to 18 provided on the wheels 11 to 14 via the inverter 19 in a regenerative state to perform motor braking. Torque Tmr is generated, and the friction brake mechanisms 21 to 24 provided on the wheels 11 to 14 are actuated in a braking state via the brake actuator 25, that is, the in-wheel motors 15 to 18 and the friction brake mechanisms. Friction braking force Bf is generated in cooperation with 21-24. At this time, the electronic control unit 26 increases, for example, a motor braking torque Tmr that increases in proportion to the depression force P at an initial stage of the depression operation of the brake pedal B by the driver and is held constant thereafter, and a motor braking torque Tmr. The basic braking force distributes the motor braking torque Tmr and the friction braking force Bf so that the required braking force F0 is the sum of the friction braking force Bf that increases in proportion to the stepping force P when the pressure is held constant. Determine as distribution.

  The electronic control unit 26 then operates the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24 based on the determined basic braking force distribution to generate the necessary braking force F0 on the wheels 11 to 14, respectively. Then, the process proceeds to step S13. When each in-wheel motor 15-18 generates motor braking torque Tmr in a regenerative state based on this basic braking force distribution, the generated regenerative power (electric energy) is converted to inverter 19 (more specifically, a three-phase inverter circuit). ) To be stored in the battery constituting the power storage device 20.

  In step S13, the electronic control unit 26 regeneratively brakes at least the in-wheel motors 15 to 18 among the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24, thereby braking the wheels 11 to 14. Anti-skid control for controlling the braking force of each of the wheels 11 to 14 when the slip caused by the control is excessive (has a tendency to lock) (hereinafter, anti-skid control defined in this way is referred to as eABS control). It is determined whether or not is necessary. Hereinafter, the determination process in step S13 will be specifically described.

  First, the electronic control unit 26 detects each wheel speed Vwi (i = fl, fr) detected by the wheel speed sensor 28i (i = fl, fr, rl, rr) from the vehicle state information acquired in step S11. , Rl, rr), the estimated vehicle speed Vb is estimated, and the slip ratio Si is calculated as the deviation between the estimated vehicle speed Vb and each wheel speed Vwi (i = fl, fr, rl, rr) for each wheel 11-14. (I = fl, fr, rl, rr) is calculated. Here, for the calculation of the estimated vehicle body speed Vb and the slip ratio Si (i = fl, fr, rl, rr), a well-known calculation method that has been widely used can be employed. Let me explain.

  As for the estimated vehicle body speed Vb, the electronic control unit 26 first sets a value that is considered to be the closest to the actual vehicle body speed among the wheel speeds Vwi (i = fl, fr, rl, rr) of the wheels 11 to 14. Select as speed Vwb. Next, the electronic control unit 26 calculates the estimated vehicle body speed Vbn1 obtained by subtracting the positive constant α1 for suppressing the increase rate of the estimated vehicle body speed from the previously calculated vehicle body estimated speed Vbf and the decrease rate of the estimated vehicle body speed. An estimated vehicle speed Vbn2 is calculated by adding a positive constant α2 for suppression. Then, the electronic control unit 26 estimates (determines) an intermediate value among the selected estimated vehicle speed Vwb, the calculated estimated vehicle speed Vbn1, and the calculated estimated vehicle speed Vbn2 as the current estimated vehicle speed Vb.

  Regarding the slip ratio Si (i = fl, fr, rl, rr), the electronic control unit 26 determines the wheel speeds Vwi (i = fl, fr, fr) of the wheels 11 to 14 from the estimated (determined) estimated vehicle body speed Vb. rl and rr) are reduced. Then, the electronic control unit 26 estimates the slip ratio Si (i = fl, fr, rl, rr) of each wheel 11 to 14 by dividing the subtracted value by the estimated vehicle speed Vb. To calculate. In the following description, for easy understanding, the slip ratio Si (i = fl, fr, rl, rr) of each of the wheels 11 to 14 is also simply referred to as a wheel slip ratio S.

  The electronic control unit 26, for example, has the estimated vehicle body speed Vb estimated to be larger than a predetermined vehicle body speed Vbs set in advance, and the calculated wheel slip ratio S is larger than a predetermined slip ratio Ss. It is determined whether the condition is satisfied. If the condition is satisfied by this determination, the electronic control unit 26 determines “Yes” because eABS control is necessary, and proceeds to step S14. On the other hand, when the condition is not satisfied, the electronic control unit 26 determines “No”, returns to Step S11, and executes the respective step processes of Step S12 and Step S13.

  In step S14, the electronic control unit 26 estimates and calculates the friction coefficient μ of the road surface on which the vehicle Ve is currently traveling, and the estimated and calculated friction coefficient μ of the road surface is determined from a predetermined friction coefficient μ0 set in advance. It is determined whether or not it is larger. That is, the electronic control unit 26 calculates the wheel slip ratio S calculated in step S13 based on the S-μ characteristic determined as shown in FIG. 5 as the relationship between the road friction coefficient and the wheel slip ratio. The road surface friction coefficient μ corresponding to is estimated and calculated. Here, as shown in FIG. 5, the S-μ characteristic indicates that as the wheel slip rate S increases, the road friction coefficient μ increases, and when the wheel slip rate S exceeds a certain value, the wheel slip rate S increases. As the rate S increases, the road surface friction coefficient μ gradually changes. Note that for the estimation calculation of the friction coefficient μ of the road surface, the friction coefficient of the road surface changes according to the state of the road surface. Therefore, instead of using the S-μ characteristic shown in FIG. It is also possible to estimate and calculate the friction coefficient μ of the road surface that becomes the maximum value according to the road surface state on which the vehicle Ve is traveling.

  The electronic control unit 26 determines that the estimated friction coefficient μ of the road surface is larger than the predetermined friction coefficient μ0, in other words, when the road surface friction coefficient μ is relatively large and the wheels 11 to 14 are difficult to lock. Determines “Yes” and executes each step processing after step S15. On the other hand, if the estimated friction coefficient μ of the road surface is equal to or less than the predetermined friction coefficient μ0, in other words, if the road surface friction coefficient μ is extremely small and the wheels 11 to 14 are easily locked, the electronic control unit 26 is In step S14, “No” is determined, and each step processing after step S17 is executed.

  Here, the predetermined friction coefficient μ0 will be described. As described in step S12, in the basic braking force distribution, the required braking force F0 is determined by the motor braking torque Tmr generated by the in-wheel motors 15-18 operating in the regenerative state and the friction brake mechanisms 21-21. The wheels 11 to 14 are generated as a sum of the friction braking force Bf generated by the operation of the brake 24 in the braking state. In this case, the frictional braking force Bf generated by each of the friction brake mechanisms 21 to 24 depends on the magnitude of the road surface friction coefficient μ, and toward “0” as the road surface friction coefficient μ decreases. Decrease. Therefore, in the present invention, the friction braking force Bf cannot be applied to the road surface. In other words, the friction coefficient at which the size (distribution) of the friction braking force Bf is “0” in the basic braking force distribution is set to a predetermined value. It is defined as the friction coefficient μ0.

  In step S15, the electronic control unit 26 executes eABS control in a situation where the estimated friction coefficient μ of the road surface is larger than a predetermined friction coefficient μ0 and the wheels 11 to 14 are relatively difficult to lock. The braking forces 11 to 14 are independently controlled. In this case, the electronic control unit 26 operates each in-wheel motor 15 to 18 provided on each wheel 11 to 14 independently in a regenerative state (that is, generates a motor braking torque Tmr), or each wheel. Each in-wheel motor 15-18 provided in 11-14 is independently operated by a power running state (namely, motor drive torque Tmc is generated), and the vehicle Ve which tends to be locked is braked appropriately. .

ただし、前記式１中のμは前記ステップＳ１４にて推定して演算した路面の摩擦係数を表すものであり、Wは各車輪１１〜１４の位置における荷重を表すものである。従って、前記式１の右辺第１項のμWは車輪と路面との間に発生する摩擦力すなわち必要制動力F0を表すものである。ここで、以下の説明においては、必要制動力F0を目標総制動力F0とも称呼する。又、前記式１中の摩擦制動力Bfr及びモータ制動トルクTmrはそれぞれ絶対値を表すものである。尚、必要制動力F0（目標総制動力F0）、モータ制動トルクTmr及び摩擦制動力Bfrは、作用方向を加味した場合、それぞれ、正の値として表すと良い。 Here, in the eABS control, the electronic control unit 26 operates the in-wheel motors 15 to 18 provided on the wheels 11 to 14 independently in a regenerative state (that is, generates the motor braking torque Tmr). The friction braking force Bfr generated by the friction brake mechanisms 21 to 24 provided on the wheels 11 to 14 is calculated according to the following equation 1.

However, μ in the equation 1 represents the friction coefficient of the road surface estimated and calculated in step S14, and W represents the load at the position of each wheel 11-14. Therefore, μW in the first term on the right side of the equation 1 represents the frictional force generated between the wheel and the road surface, that is, the necessary braking force F0. Here, in the following description, the necessary braking force F0 is also referred to as a target total braking force F0. Further, the friction braking force Bfr and the motor braking torque Tmr in the above formula 1 each represent an absolute value. The necessary braking force F0 (target total braking force F0), the motor braking torque Tmr, and the friction braking force Bfr are each preferably expressed as a positive value when the action direction is taken into account.

  That is, in the eABS control, when the in-wheel motors 15 to 18 provided on the wheels 11 to 14 are operated in a regenerative state, the in-wheel motors 15 to 18 generate motor braking torque Tmr. According to Equation 1, the friction braking force Bfr (absolute value) is calculated as a difference by subtracting the motor braking torque Tmr (absolute value) from the target total braking force F0 (absolute value). In other words, the target total braking force F0 (absolute value) is realized as the sum of the friction braking force Bfr (absolute value) and the motor braking torque Tmr (absolute value) whose action directions are the same direction.

Further, in the eABS control, the electronic control unit 26 operates the in-wheel motors 15 to 18 provided on the wheels 11 to 14 independently by the power running state (that is, generates the motor driving torque Tmc). The friction braking force Bfc generated by each friction brake mechanism 21 to 24 provided on each wheel 11 to 14 is calculated according to the following equation 2.

  That is, in the eABS control, when the in-wheel motors 15 to 18 provided on the wheels 11 to 14 are operated in a power running state, the in-wheel motors 15 to 18 generate motor driving torque Tmc. According to Equation 2, the friction braking force Bfc (absolute value) is calculated as a difference by adding the motor driving torque Tmc (absolute value) to the target total braking force F0 (absolute value). In other words, the target total braking force F0 (absolute value) is realized as a difference between the friction braking force Bfc (absolute value) and the motor driving torque Tmc (absolute value) having different acting directions.

  Therefore, in step S15, when the electronic control unit 26 operates the in-wheel motors 15 to 18 in the regenerative state according to the eABS control, the friction control determined in step S12 as the basic braking force distribution according to the above equation 1. The friction braking force Bfr generated by each of the friction brake mechanisms 21 to 24 is calculated by reducing the power Bf. When the electronic control unit 26 operates the in-wheel motors 15 to 18 in the power running state according to the eABS control, the electronic control unit 26 increases the friction braking force Bf determined in step S12 as the basic braking force distribution according to the equation 2. Thus, the friction braking force Bfc generated by each friction brake mechanism 21 to 24 is calculated. Then, the electronic control unit 26 proceeds to step S16.

  In step S16, the electronic control unit 26 operates the in-wheel motors 15 to 18 in the regenerative state via the inverter 19 to generate motor braking torque Tmr, or operates in the power running state to drive the motor drive torque Tmc. Is generated. Also, the electronic control unit 26 operates the friction brake mechanisms 21 to 24 in a braking state via the brake actuator 25 to generate the friction braking force Bfr and the friction braking force Bfc. Then, when the electronic control unit 26 executes the eABS control by cooperating the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24 in this way, the electronic control unit 26 proceeds to step S19 and temporarily ends the execution of the eABS control program. After the elapse of a predetermined short time, the execution of the program is started again at step S10.

  On the other hand, if the estimated friction coefficient μ of the road surface is equal to or less than the predetermined friction coefficient μ0 in step S14, the electronic control unit 26 determines “No” and executes the step process of step S17.

  That is, the electronic control unit 26 executes the eABS control under the condition that the estimated friction coefficient μ of the road surface is equal to or less than a predetermined friction coefficient μ0, that is, the road surface friction coefficient μ is extremely small and the wheels 11 to 14 are easily locked. Then, the braking force is independently controlled so that the locked state of the wheels 11 to 14 is canceled at an early stage. In this case, the electronic control unit 26 operates each in-wheel motor 15-18 provided in each wheel 11-14 independently by a power running state, in order to cancel the locked state of each wheel 11-14 at an early stage. (That is, by generating the motor driving torque Tmc), the vehicle Ve that tends to be locked is braked appropriately.

  For this reason, when the estimated friction coefficient μ of the road surface is equal to or less than the predetermined friction coefficient μ0, the electronic control unit 26 determines the friction braking force determined in step S12 as the basic braking force distribution according to the equation 2. The friction braking force Bfc generated by each of the friction brake mechanisms 21 to 24 is calculated so as to be larger than Bf. Thus, when the friction braking force Bfc corresponding to operating each in-wheel motor 15-18 by a power running state according to eABS control is calculated, the electronic control unit 26 will progress to step S18.

  In step S18, the electronic control unit 26 operates the in-wheel motors 15 to 18 in the power running state via the inverter 19 to generate motor drive torque Tmc. Further, the electronic control unit 26 operates the friction brake mechanisms 21 to 24 in a braking state via the brake actuator 25 to generate a friction braking force Bfc. Then, the electronic control unit 26 proceeds to step S19, once ends the execution of the eABS control program, and after a predetermined short time has elapsed, starts the execution of the program again in step S10.

  By the way, in the situation where each in-wheel motor 15-18 operates in a regenerative state, the rotational energy (kinetic energy) of the wheels 11-14 is converted into electric energy, and the converted electric energy is output to the inverter 19 as regenerative power. To do. Then, the regenerative power (electric energy) output to the inverter 19 in this way is stored in a battery constituting the power storage device 20. In this case, the power storage device 20 (battery) can store regenerative power (electric energy) regenerated and output by each in-wheel motor 15 to 18, that is, the amount of charge (SOC: State) of the power storage device 20 In a charging situation with a small amount of charge, the in-wheel motors 15 to 18 are operated in a regenerative state to generate the motor braking torque Tmr, thereby enabling more precise eABS control. However, in a charging state where the amount of charge (SOC) of the power storage device 20 is large, it becomes impossible to store regenerative power (electric energy) regenerated and output by the in-wheel motors 15 to 18. It becomes impossible to generate the motor braking torque Tmr by operating the in-wheel motors 15 to 18 in the regenerative state.

  On the other hand, in a situation where each in-wheel motor 15 to 18 is operated in a power running state, the regenerative power (electric energy) stored in the power storage device 20 (battery) is supplied via the inverter 19, whereby the power storage device 20. It is possible to drive the wheels 11 to 14 by consuming the regenerative electric power (electric energy) stored in the motor and generating the motor driving torque Tmc. Therefore, as described above, in a situation where the amount of charge (SOC) in the power storage device 20 is fully charged, the total power including the regenerative power stored by actively operating the in-wheel motors 15 to 18 in the power running state. (Electric energy) is consumed and the in-wheel motors 15 to 18 are operated in a regenerative state. In other words, the in-wheel motors 15 to 18 are always maintained in a regenerative state. is necessary. However, the amount of charge (SOC) in the power storage device 20 may change in size (the amount of chargeable amount) depending on the state of the battery (temperature, deterioration over time, etc.) that constitutes the power storage device 20. It is difficult to always accurately detect the amount of charge (SOC).

  Therefore, in the present embodiment, the electronic control unit 26 includes the electric energy (regenerative power) input to the power storage device 20 when the in-wheel motors 15 to 18 are operated in the regenerative state, and the in-wheel motors 15 to 15. 18 controls the electrical energy (supplied power) output from the power storage device 20 by operating in the power running state, in other words, manages the history of input / output (balance) of the electrical energy by each in-wheel motor 15-18. To do. The electronic control unit 26 operates the in-wheel motors 15 to 18 in the regenerative state or the power running state during the eABS control using the input / output (balance) history of the electric energy. The magnitudes of the friction braking forces Bfr and Bfc generated by the friction brake mechanisms 21 to 24 are appropriately changed according to the state. Hereinafter, the operation control of the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24 using the electric energy input / output (balance) history will be described in detail.

  In managing the input / output (balance) of the electric energy by each in-wheel motor 15-18, the electronic control unit 26 repeatedly executes the electric energy balance management program shown in FIG. 6 at a predetermined short time interval. Specifically, the electronic control unit 26 (more specifically, the CPU) starts executing the electric energy balance management program in step S30, and in subsequent step S31, whether or not eABS control is currently being performed. Determine. That is, if the eABS control program described above is being executed, the electronic control unit 26 determines “Yes” and proceeds to step S32. On the other hand, if the eABS control program is not currently being executed, the electronic control unit 26 determines “No”, proceeds to step S38, and temporarily ends the execution of the electric energy balance management program. Then, after the elapse of a predetermined short time, the electronic control unit 26 starts executing the electric energy balance management program again in step S30.

  In step S <b> 32, the electronic control unit 26 receives the inflow electric energy E_in that flows (regenerated) from the in-wheel motors 15 to 18 toward the power storage device 20, and the in-wheel motors 15 to 18 from the power storage device 20. For example, the outflow electric energy amount E_out that has flowed out (consumed) toward the end is read and acquired from a predetermined storage position of the nonvolatile RAM, for example. That is, the electronic control unit 26 is non-volatile as an inflow electric energy amount E_in, for example, an integrated amount (history) of electric energy regenerated by the regenerative control of the in-wheel motors 15 to 18 after the vehicle starts running. An accumulated amount (history) of electrical energy consumed by the power running control of each in-wheel motor 15 to 18 after the vehicle starts running is stored in a predetermined storage position of the storage RAM. The outflow electric energy amount E_out is stored in a predetermined storage location in the nonvolatile RAM so as to be updated. And the electronic control unit 26 will progress to step S33, if the inflow electric energy amount E_in and the outflow electric energy amount E_out are acquired.

  Here, for the inflow electric energy amount E_in and the outflow electric energy amount E_out, for example, by the specifications and ratings of the in-wheel motors 13 to 18, the current detected by the current sensor provided in the inverter 19, and regenerative control or power running control It can be calculated using the time when the in-wheel motors 15 to 18 are operated. Further, the inflow electric energy amount E_in and the outflow electric energy amount E_out stored in an updatable manner represent average values of four (ie, a plurality of) in-wheel motors 15 to 18 respectively. Instead of using the inflow electric energy amount E_in and the outflow electric energy amount E_out represented by the average value, the inflow electric energy amount E_in and the outflow electric energy amount E_out in each in-wheel motor 15 to 18 are used. Needless to say, it is possible to carry out using the average value of the four (ie, a plurality of) in-wheel motors 15 to 18, and the balance of the inflow electric energy amount E_in and the outflow electric energy amount E_out The time fluctuation (change) of the balance is suppressed, and the fluctuation (change) of the friction braking force by the friction brake mechanisms 21 to 24 described later can also be suppressed.

  In step S33, the electronic control unit 26 compares the inflow electric energy amount E_in obtained in step S32 with the outflow electric energy amount E_out, and the inflow electric energy amount E_in is determined as the inflow electric energy. It is determined whether or not the amount is greater than or equal to the amount E_out. That is, if the magnitude of the inflow electrical energy amount E_in is equal to or greater than the magnitude of the outflow electrical energy amount E_out, the electronic control unit 26 determines “Yes” and proceeds to step S34. On the other hand, if the magnitude of the inflow electrical energy amount E_in is less than the magnitude of the outflow electrical energy amount E_out, the electronic control unit 26 determines “No” and proceeds to step S35.

  In step S34, the inflow electric energy amount E_in is greater than or equal to the outflow electric energy amount E_out in step S33, that is, the electric energy consumed by the in-wheel motors 15 to 18 is consumed. This process is executed when the regenerative power is stored in the power storage device 20 and is larger than the energy. Accordingly, in step S34, the electronic control unit 26 reduces the inflow electric energy amount E_in in order to balance the inflow electric energy amount E_in and the outflow electric energy amount E_out (to balance the balance). Increase the outflow electric energy E_out. Specifically, the electronic control unit 26 increases the outflow electric energy amount E_out by generating the motor driving torque Tmc in the in-wheel motors 15 to 18 as the power running control subject in the eABS control.

  Accordingly, in step S34, the electronic control unit 26 secures the target total braking force F0 in the eABS control currently being executed, and as is apparent from the above equation 2, the friction brake mechanism for the target total braking force F0 is obtained. The magnitude (median value) of the friction braking force Bfc by 21 to 24 is increased. Thus, if the magnitude | size (median value) of the friction braking force Bfc by the friction brake mechanisms 21-24 is increased, the electronic control unit 26 will progress to step S36. Then, in step S36, the electronic control unit 26 increases the magnitude (median value) of the friction braking force Bfc in accordance with the above equation 2 when executing the above-described eABS control program, for example, step S15. Then, the in-wheel motors 15 to 18 are operated according to the power running state. Thereby, the electric power including the regenerative electric power stored in the power storage device 20 can be appropriately consumed to balance the inflow electric energy amount E_in and the outflow electric energy amount E_out (to balance the balance). The in-wheel motors 15 to 18 can be maintained in a regenerative state. In this case, the electronic control unit 26 reduces the motor braking torque Tmr generated by the in-wheel motors 15 to 18 instead of actively operating the in-wheel motors 15 to 18 by the power running control main body. It is also possible to decrease the inflow electric energy amount E_in and relatively increase the outflow electric energy amount E_out.

  On the other hand, in step S35, in step S33, the amount of inflow electric energy E_in is less than the amount of outflow electric energy E_out, that is, the electric energy consumed by the in-wheel motors 15 to 18 is regenerated. This process is executed when the electric energy is larger than the electric energy and power is supplied from the power storage device 20. Accordingly, in step S35, the electronic control unit 26 reduces the outflow electric energy amount E_out in order to balance the outflow electric energy amount E_out and the inflow electric energy amount E_in (to balance the balance). Increase the inflow electric energy E_in. Specifically, in the eABS control, the electronic control unit 26 is a regenerative control main body and actively generates the motor braking torque Tmr in the in-wheel motors 15 to 18 to increase the inflow electric energy amount E_in. In this case, the electronic control unit 26 reduces the motor driving torque Tmc generated by the in-wheel motors 15 to 18 instead of actively operating the in-wheel motors 15 to 18 by the regenerative control main body. It is also possible to decrease the outflow electric energy amount E_out and relatively increase the inflow electric energy amount E_in.

  Accordingly, in step S35, the electronic control unit 26 maintains the target total braking force F0 in the eABS control currently being executed, so that the friction brake mechanism with respect to the target total braking force F0, as is clear from the above-described equation (1). The magnitude (median value) of the friction braking force Bfr by 21 to 24 is decreased. Thus, if the magnitude | size (median value) of the friction braking force Bfr by the friction brake mechanisms 21-24 is increased, the electronic control unit 26 will progress to step S36. Then, in step S36, the electronic control unit 26 reduces the magnitude (median value) of the friction braking force Bfr so as to comply with the above equation 1 when executing the above-described eABS control program, for example, step S15. Then, the in-wheel motors 15 to 18 are actively operated in the regenerative state. Thereby, regenerative electric power can be stored in the power storage device 20 to balance the outflow electric energy amount E_out and the inflow electric energy amount E_in (balance the balance), and the in-wheel motors 15 to 18 can be balanced. This enables more precise eABS control using the motor braking torque Tmr generated by

  Here, a situation in which the step S34 or the step S35 is executed according to the determination process in the step S33 will be described with reference to FIG.

  Now, it is assumed that the absolute value of the target total braking force F0 gradually increases in accordance with the brake operation by the driver, as indicated by a thick solid line in the upper part of FIG. 7, and eABS control is required. In this case, the electronic control unit 26 has a situation where the inflow electric energy amount E_in is smaller than the outflow electric energy amount E_out based on the inflow electric energy amount E_in and the outflow electric energy amount E_out that have been accumulated so as to be updated as history. Then, for example, in accordance with the above equation 1, in addition to causing the in-wheel motors 15 to 18 to generate the motor braking torque Tmr based on the regenerative control as shown by the solid line in the lower part of FIG. 7, the upper part of FIG. As indicated by the broken line, the friction braking mechanisms 21 to 24 generate the friction braking force Bfr to secure the target total braking force F0. Thus, in the situation where the in-wheel motors 15 to 18 generate the motor braking torque Tmr, as described above, the inflow electric energy amount E_in is increased and regenerative power is generated and stored in the power storage device 20.

  For this reason, the electronic control unit 26 regenerates the current eABS control based on the current inflow electric energy amount E_in and the outflow electric energy amount E_out accumulated so as to be renewable as a history. When the generated inflow electric energy amount E_in becomes larger than the outflow electric energy amount E_out by adding the generated inflow electric energy amount E_in, as shown in the lower part of FIG. 7, the regeneration control main body shifts to the power running control main body. When shifting to the power running control, the electronic control unit 26 increases the magnitude (median value) of the friction braking force Bfc generated by the friction brake mechanisms 21 to 24 as shown in the upper part of FIG. Ensure total braking force F0. In this manner, in the situation where the friction braking mechanisms 21 to 24 generate a large friction braking force Bfc while generating the motor driving torque Tmc in the in-wheel motors 15 to 18 by the power running control, as described above, the outflow electric energy amount E_out Increases and the power stored in the power storage device 20 is consumed.

  For this reason, the electronic control unit 26, with the passage of time, by the power running control in the current eABS control based on the inflow electric energy amount E_in and the outflow electric energy amount E_out that have been accumulated so as to be updated as history. When the generated outflow electric energy amount E_out becomes larger than the inflow electric energy amount E_in by adding the generated outflow electric energy amount E_out, as shown in the lower part of FIG. When shifting to the regenerative control, the electronic control unit 26 decreases the magnitude (median value) of the friction braking force Bfr generated by the friction brake mechanisms 21 to 24 as shown in the upper part of FIG. Ensure total braking force F0.

  As described above, the in-wheel motor in the situation where the electronic control unit 26 increases the inflow electric energy amount E_in according to the balance (balance of balance) between the inflow electric energy amount E_in and the outflow electric energy amount E_out. In a situation where the magnitude (median value) of the friction braking force Bfc of the friction brake mechanism 21 to 24 is increased in order to operate 15 to 18 independently in the power running state, and the amount of outflow electric energy E_out increases, the in-wheel motor 15 In order to activate .about.18 independently and actively in a regenerative state, the magnitude (median value) of the friction braking force Bfr of the friction brake mechanisms 21 to 24 can be reduced. Thus, more precise eABS control using the in-wheel motors 15 to 18 can be executed regardless of the state of charge or operation of the battery constituting the power storage device 20.

  When the eABS control program described above is executed in step S36, the electronic control unit 26 proceeds to step S37. In step S37, the electronic control unit 26 accumulates the inflow electric energy amount E_in and the outflow energy amount E_out generated as a result of the execution of the eABS control program as a history, and the inflow electric energy amount E_in and the outflow electric energy thus far stored. It is updated by adding (accumulating) to the quantity E_out, and stored in a predetermined storage location of the nonvolatile RAM. Then, the electronic control unit 26 once ends the execution of the electric energy balance management program in step S38, and starts executing the program again in step S30 after a predetermined short time has elapsed.

  As can be understood from the above description, according to the first embodiment, the electronic control unit 26 maintains the balance between the inflow electric energy amount E_in and the outflow electric energy amount E_out in the eABS control. The target total braking force F0 can be generated on each of the wheels 11 to 14 by controlling the magnitudes of the friction braking forces Bfr and Bfc by the friction brake mechanisms 21 to 24 so that the balance is maintained. That is, based on the accumulated electric energy balance history, the electronic control unit 26 determines that the inflow electric energy amount E_in is greater than or equal to the outflow electric energy amount E_out, in other words, the inflow electric energy amount. When the regenerative power that is E_in is stored in the power storage device 20, the in-wheel motors 15 to 18 are operated according to the power running state in order to consume this inflow electric energy amount E_in (regenerative power), in other words, the outflow Increase the amount of electrical energy E_out. In this case, as the in-wheel motors 15 to 18 generate the motor driving torque Tmc, the electronic control unit 26 performs friction control by the friction brake mechanisms 21 to 24 in order to secure the target total braking force F0. Increase the size of power Bfc. Thereby, it can suppress that inflow electric energy amount E_in (regenerative electric power) is supplied to the electrical storage apparatus 20, and is stored, As a result, it is as needed irrespective of the electrical storage state (SOC) in the electrical storage apparatus 20. Thus, it is possible to always maintain a state in which the in-wheel motors 15 to 18 can be operated in the regenerative state.

  Further, the electronic control unit 26 determines that the inflow electric energy amount E_in is less than the outflow electric energy amount E_out based on the accumulated electric energy balance history, in other words, in the power storage device 20. When the amount of electrical energy (SOC) decreases, the in-wheel motors 15 to 18 can be actively operated in the regenerative state. In this case, as the in-wheel motors 15 to 18 generate the motor braking torque Tmr, the electronic control unit 26 controls the friction control by the friction brake mechanisms 21 to 24 in order to secure the target total braking force F0. Decrease the size of the power Bfr. Thereby, more precise eABS control can be performed using the motor braking torque Tmr by the in-wheel motors 15 to 18. Therefore, smooth and stable braking is possible, and the driver does not feel uncomfortable.

b. Second Embodiment In the first embodiment, the inflow electric energy amount E_in and the outflow electric energy amount by the in-wheel motors 15 to 18 in the situation where the eABS control is performed by executing the electric energy balance management program. Based on E_out, we implemented a balance between these electric energies (to balance the balance). Specifically, in order to keep the in-wheel motors 15 to 18 in a regenerative state based on the comparison between the inflow electric energy amount E_in and the outflow electric energy amount E_out, The motors 15 to 18 were operated in a regenerative state or a power running state, and the magnitudes (median values) of the friction braking forces Bfr and Bfc by the friction brake mechanisms 21 to 24 were appropriately changed.

  By the way, in the eABS control, when a front obstacle exists in the traveling direction of the vehicle Ve, the friction brake mechanisms 21 to 24 are mainly used according to the relative positional relationship between the vehicle Ve and the front obstacle. The in-wheel motors 15 to 18 are mainly operated to be braked. That is, as a relative positional relationship between the vehicle Ve and the front obstacle, for example, when braking the vehicle Ve under a large distance based on the distance from the vehicle Ve to the front obstacle, the vehicle Ve is relatively dense. Since no eABS control is required, the friction brake mechanisms 21 to 24 are mainly operated. On the other hand, when braking the vehicle Ve in a situation where the distance becomes smaller, since precise eABS control is required as the distance becomes smaller, the in-wheel motors 15-18 are mainly composed of the friction brake mechanisms 21-24. Is operated mainly. Therefore, in a situation where an increase in the inflow electric energy amount E_in by the in-wheel motors 15 to 18 is predicted with the passage of time, such as the relative positional relationship between the vehicle Ve and the front obstacle, The friction brake mechanisms 21 to 24 are mainly operated or the in-wheel motors 15 to 18 are operated in a power running state to suppress an increase in the inflow electric energy amount E_in, and the in-wheel motors 15 to 18 are always regenerated. It needs to be kept in a possible state. Hereinafter, although this 2nd Embodiment is described in detail, the same code | symbol is attached | subjected to the same part as the said 1st Embodiment, and the detailed description is abbreviate | omitted.

  In the second embodiment, a radar sensor 29 is provided on the vehicle Ve as shown by a broken line in FIG. The radar sensor 29 is assembled at the front end portion of the vehicle Ve (for example, near the front grille), and based on the time required for transmitting and receiving millimeter waves, the radar sensor 29 is connected to a front obstacle existing in a predetermined range in front of the vehicle Ve. A relative distance D representing a relative distance is detected. The radar sensor 29 outputs a signal representing the relative speed D to the electronic control unit 26.

  In the second embodiment, the electronic control unit 26 executes a braking force control program shown in FIG. That is, the electronic control unit 26 starts execution of the braking force control program shown in FIG. 8 at step S50, and determines whether eABS control is currently being performed at step S51. That is, as in the case of the first embodiment described above, the electronic control unit 26 determines “Yes” if the eABS control program is being executed, proceeds to step S52, and is not executing the eABS control program. It determines with "No" and progresses to step S60, and execution of a braking force control program is once complete | finished. In this case, the electronic control unit 26 starts executing the braking force control program again in step S50 after a predetermined short time has elapsed.

  In step S52, the electronic control unit 26 inputs the signal output from the radar sensor 29, and the relative distance D to the front obstacle existing in front of the vehicle Ve (hereinafter simply referred to as the distance D). get. And if the electronic control unit 26 acquires the distance D, it will progress to step S53.

  In step S53, the electronic control unit 26 determines that the distance D acquired in step S52 is greater than the determination distance Df set in advance to determine whether or not the friction brake mechanisms 21 to 24 are mainly operated. It is determined whether or not it is small. That is, if the distance D is equal to or greater than the determination distance Df, the electronic control unit 26 determines “No” and proceeds to step S54. On the other hand, if the distance D is less than the determination distance Df, the electronic control unit 26 determines “Yes” and proceeds to step S55.

  In step S54, since the distance D between the vehicle Ve and the front obstacle is still large, the electronic control unit 26 performs eABS control that mainly operates the friction brake mechanisms 21 to 24. That is, in this case, the electronic control unit 26 performs the friction braking force Bfr generated by the friction brake mechanisms 21 to 24 with respect to the target total braking force F0 when executing the above-described eABS control program, for example, step S15. , Bfc is controlled to increase Bfc. Thus, in a situation where the distance D is equal to or greater than the determination distance Df, the friction brake mechanisms 21 to 24 are mainly operated to suppress an increase in the inflow electric energy amount E_in due to the regenerative state of the in-wheel motors 15 to 18. When the electronic control unit 26 operates the friction brake mechanisms 21 to 24 mainly, the electronic control unit 26 proceeds to step S60, temporarily terminates execution of the braking force control program, and again after step elapses in a predetermined short time. Start program execution.

  In step S55, the electronic control unit 26 determines that the distance D acquired in step S52 is greater than or equal to a predetermined determination distance Dm for determining whether or not the in-wheel motors 15 to 18 are operated mainly. It is determined whether or not there is. That is, if the distance D is greater than or equal to the determination distance Dm, the electronic control unit 26 determines “Yes” and proceeds to step S56. On the other hand, if the distance D is less than the determination distance Dm, the electronic control unit 26 determines “No” and proceeds to step S57.

  The step process of step S56 determines whether or not the distance D between the vehicle Ve and the front obstacle activates the friction brake mechanisms 21 to 24 mainly according to the determination process of step S53 and step S55. This is a process executed when the distance is less than the determination distance Df and is equal to or greater than the determination distance Dm for determining whether or not the in-wheel motors 15 to 18 are mainly operated. For this reason, in step S56, the electronic control unit 26 shifts the object to be mainly operated in the eABS control from the friction brake mechanisms 21 to 24 to the in-wheel motors 15 to 18, but in the future, each in-wheel motor 15 to In order to keep 18 in a regenerative state, an increase in the inflow electric energy E_in is suppressed. Specifically, the electronic control unit 26 increases the outflow electric energy amount E_out by generating the motor driving torque Tmc in the in-wheel motors 15 to 18 as the power running control subject in the eABS control.

  Accordingly, in step S56, the electronic control unit 26, in order to secure the target total braking force F0 in the currently executed eABS control, as shown in the equation 2, the friction brake against the target total braking force F0. The magnitude (median value) of the friction braking force Bfc by the mechanisms 21 to 24 is increased. As described above, when the magnitude (median value) of the friction braking force Bfc by the friction brake mechanisms 21 to 24 is increased and the in-wheel motors 15 to 18 are operated by the power running control main body, the electronic control unit 26 proceeds to step S58. move on.

  On the other hand, the step process of step S57 determines whether or not the distance D between the vehicle Ve and the front obstacle activates the in-wheel motors 15 to 18 mainly according to the determination process of the step S53 and the step S55. In other words, it is a process that is executed in a situation where precise eABS control is required when the determination distance is less than the determination distance Dm. For this reason, in step S57, the electronic control unit 26 shifts the subject to be operated mainly in the eABS control from the friction brake mechanisms 21 to 24 to the in-wheel motors 15 to 18, and the in-wheel motors 15 to 18 are mainly used for regenerative control. Motor braking torque Tmr is generated.

  As a result, the electronic control unit 26, in step S57, in order to secure the target total braking force F0 in the currently executed eABS control, the friction with respect to the target total braking force F0, as is apparent from the above equation 1. The magnitude (median value) of the friction braking force Bfr by the brake mechanisms 21 to 24 is decreased. Thus, when the magnitude (median value) of the friction braking force Bfr by the friction brake mechanisms 21 to 24 is decreased and the in-wheel motors 15 to 18 are operated by the regenerative control main body, the electronic control unit 26 proceeds to step S58. move on.

  Here, in the braking force control program of the second embodiment, as is apparent from each step processing from step S52 to step S57, the friction brake mechanisms 21 to 24 with respect to the target total braking force F0. The ratios of the friction braking force Bfr and the friction braking force Bfc to the motor braking torque Tmr and the motor driving torque Tmc of the in-wheel motors 15 to 18 are determined by the distance D. That is, in the braking force control program of the second embodiment, the ratio between the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24 is the distance D between the vehicle Ve and the front obstacle. It can be said that it is determined as a function.

  In step S58, the electronic control unit 26 takes into account the inflow electric energy amount E_in and the outflow electric energy amount E_out depending on the operation state of the in-wheel motors 15 to 18 in the step S56 or the step S57, and the first implementation described above. The electric energy balance management program is executed in the same manner as the form. Note that when the electric energy balance management program is executed in step S58, step S31 shown in FIG. 6 is omitted. Then, when the electronic control unit 26 executes the electric energy balance management program in step S58, the electronic control unit 26 proceeds to step S59.

  In step S59, the electronic control unit 26 executes the eABS control program as in the first embodiment described above. When the electronic control unit 26 executes the eABS control program in step S59, the electronic control unit 26 proceeds to step S60 to end the braking force control program once. After a predetermined short period of time has elapsed, the electronic control unit 26 again performs the braking force control program in step S50. Start running.

  As can be understood from the above description, in the second embodiment, the distance D between the vehicle Ve and the front obstacle is used to control the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24. The ratio to control can be determined as a function of distance D. And also in the ratio of the control of the in-wheel motors 15-18 determined in this way and the control of the friction brake mechanisms 21-24, the increase in inflow electric energy amount E_in is suppressed, and each in-wheel motor 15- is always set. 18 can be maintained in a regenerative state. Therefore, for example, even in a highly urgent situation where a collision between the vehicle Ve and a front obstacle is avoided, an effect equivalent to that of the first embodiment can be obtained.

c. Modification of Second Embodiment In the second embodiment, the distance D between the vehicle Ve and the front obstacle is used to control the in-wheel motors 15 to 18 and the friction brake mechanisms 21 to 24. The proportion was determined to be determined as a function of distance D. As a result, assuming the situation where the amount of inflow electric energy E_in from the in-wheel motors 15 to 18 is increased due to an increase in the regenerative control opportunity, the friction brake mechanisms 21 to 24 are used when the distance D is equal to or greater than the determination distance Df. The in-wheel motors 15 to 18 are actuated by the power running control main body when the distance D is less than the determination distance Df and greater than or equal to the determination distance Dm. The E_out is increased and the friction braking force Bfc by the friction brake mechanisms 21 to 24 is increased to suppress an increase in the inflow electric energy amount E_in. Thus, the distance D is less than the determination distance Dm, and the in-wheel motors 15 to 18 are surely able to generate the motor braking torque Tmr even in a situation where the in-wheel motors 15 to 18 are operated by the regenerative control main body. .

  By the way, assuming the situation where the inflow electric energy amount E_in will increase, when determining the ratio between the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24, For example, the vehicle speed of the vehicle Ve, the depression speed of the brake pedal B by the driver, the magnitude of the target total braking force F0, the rate of change of the target total braking force F0, etc. are used. Can do. That is, it is possible to determine the ratio between the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24 as a function of the vehicle speed, the depression speed, the magnitude of the target total braking force F0, and the rate of change. .

  Specifically, for example, when determining the ratio between the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24 as a function of the vehicle speed, the time by the in-wheel motors 15 to 18 when the vehicle speed of the vehicle Ve is high. When the inflow electric energy E_in (regenerative electric energy) per unit increases, the friction brake mechanisms 21 to 24 are operated mainly (that is, the in-wheel motors 15 to 18 are operated mainly by the power running control), and the vehicle speed becomes low. Further, the in-wheel motors 15 to 18 can be operated by the regenerative control main body. As a result, an increase in the inflow electric energy amount E_in can be suppressed, and the in-wheel motors 15 to 18 are reliably driven by the motor braking torque in a situation where the vehicle speed is reduced and the in-wheel motors 15 to 18 are operated by the regenerative control main body. Can generate Tmr.

  For example, when the ratio between the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24 is determined as a function of the depression speed of the brake pedal B immediately before execution of the eABS control, the depression speed of the brake pedal B is Since the urgency level is low when it is late, the friction brake mechanisms 21 to 24 are operated mainly (that is, the in-wheel motors 15 to 18 are operated mainly by the power running control), and when the stepping speed is high, the urgency level is high and the in-wheel motor 15 -18 can be operated by the regeneration control main body. Also by this, the increase in the inflow electric energy E_in can be suppressed, and the in-wheel motors 15 to 18 are surely operated in a situation where the in-wheel motors 15 to 18 are operated by the regenerative control main body due to the increased urgency. Braking torque Tmr can be generated.

  For example, when determining the ratio between the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24 as a function of the magnitude of the target total braking force F0, the road surface friction coefficient μ is high and the target total control is high. When the magnitude of the power F0 is large, the friction brake mechanisms 21 to 24 are operated mainly (that is, the in-wheel motors 15 to 18 are operated mainly by the power running control), the road surface friction coefficient μ is low, and the target total braking force F0 is large. When the height becomes smaller, the in-wheel motors 15 to 18 can be operated by the regenerative control main body. Also by this, the increase in the inflow electric energy amount E_in can be suppressed, and the in-wheel motors 15 to 18 can surely generate the motor braking torque Tmr under the situation where the in-wheel motors 15 to 18 are operated by the regenerative control main body. .

  Further, for example, when the ratio between the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24 is determined as a function of the change rate of the target total braking force F0, the change rate of the target total braking force F0 is large. Sometimes the friction brake mechanisms 21 to 24 are operated mainly (that is, the in-wheel motors 15 to 18 are operated mainly by the power running control), and when the change rate of the target total braking force F0 becomes small, the in-wheel motors 15 to 18 are regenerated. It can be operated by the control subject. Also by this, the increase in the inflow electric energy amount E_in can be suppressed, and the in-wheel motors 15 to 18 can surely generate the motor braking torque Tmr under the situation where the in-wheel motors 15 to 18 are operated by the regenerative control main body. .

  Therefore, in this way, the control of the in-wheel motors 15 to 18 and the control of the friction brake mechanisms 21 to 24 as a function of the vehicle speed of the vehicle Ve, the depression speed of the brake pedal B, the magnitude and rate of change of the target total braking force F0, Even when the ratio is determined, the same effect as in the second embodiment can be expected.

  In carrying out the present invention, the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the object of the present invention.

  For example, in each of the above-described embodiments and modifications, the in-wheel motors 15 to 18 are provided on the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14, respectively. In this case, as long as it is possible to independently generate the motor braking torque Tmr and the motor driving torque Tmc, any configuration is adopted without being limited to incorporating the in-wheel motors 15 to 18 into the respective wheels 11 to 14. You may do it. Specifically, a predetermined rotational force (torque) is independently applied to the axles that rotatably support the left and right front wheels 11 and 12 and the left and right rear wheels 13 and 14, so that the motor braking torque Tmr and the motor driving are applied. A configuration that generates the torque Tmc can be employed.

  Moreover, in each said embodiment and modification, although implemented using the three-phase alternating current synchronous motor as the in-wheel motors 15-18, it is not limited to this. Even when other types of electric motors (motors) are employed, the left and right front wheels 11 and 12 are balanced in order to balance the inflow electric energy amount E_in and the outflow electric energy amount E_out (to balance the balance). And since the electric motors (motors) provided on the left and right rear wheels 13 and 14 can be operated in a regenerative state or a power running state, the same effects as those in the above embodiments and modifications can be expected.

  Furthermore, in each said embodiment and modification, it implemented by assuming the battery which comprises the electrical storage apparatus 20 as a means to store regenerated electric power (electrical energy). In this case, the electronic control unit 26 operates the in-wheel motors 15 to 18 in a regenerative state or a power running state based on the balance (balance) between the inflow electric energy amount E_in and the outflow electric energy amount E_out in the in-wheel motors 15 to 18. Therefore, even when the power storage device 20 is configured by, for example, a capacitor or a capacitor, the power storage device 20 can be implemented in exactly the same manner as the above embodiments and modifications.

  DESCRIPTION OF SYMBOLS 11, 12 ... Front wheel, 13, 14 ... Rear wheel, 15, 16, 17, 18 ... Electric motor (in-wheel motor), 19 ... Inverter, 20 ... Power storage device, 21, 22, 23, 24 ... Brake mechanism, 25 ... Brake actuator, 26 ... electronic control unit, 27 ... brake sensor, 28 ... wheel speed sensor, 29 ... radar sensor, Ve ... vehicle, B ... brake pedal

Claims (7)

An electric force generating mechanism for generating an electromagnetic driving force or an electromagnetic braking force on a vehicle wheel; an electric storage means electrically connected to the electric force generating mechanism; and at least the electric force generating mechanism A braking force generation mechanism that generates a mechanical braking force for the wheels rotated by electromagnetic driving force, a braking operation means that is operated by a driver to brake the vehicle, and The electromagnetic braking force generated by operating the electric force generation mechanism in a regenerative state according to an operation or the electromagnetic driving force generated by operating the electric force generation mechanism in a power running state, and the control In a braking force control device for a vehicle, comprising a braking control means for controlling the mechanical braking force by a power generation mechanism to generate braking force on the wheels,
The braking control means includes
The inflowing electric energy flowing from the electric force generation mechanism into the power storage means as the electric force generation mechanism is operated in the regenerative state to generate the electromagnetic braking force, and the electric force generation mechanism And accumulating and accumulating outflow electric energy amount flowing out from the power storage means to the electric force generation mechanism in association with generating the electromagnetic driving force by operating in the power running state,
When determining the target braking force to be generated on the wheel according to the road surface condition where the vehicle travels and generating the target braking force on the wheel, the balance between the inflow electric energy amount and the outflow electric energy amount is maintained. Controlling the magnitude of the mechanical braking force by the braking force generation mechanism , and
The braking control means includes
When the magnitude of the inflow electrical energy amount is equal to or greater than the magnitude of the outflow electrical energy amount, the magnitude of the mechanical braking force by the braking force generation mechanism is increased and the power running of the electric force generation mechanism is increased. Increase the operation according to the state, or decrease the electromagnetic braking force due to the regenerative state of the electric power generation mechanism,
When the magnitude of the inflow electrical energy amount is less than the magnitude of the outflow electrical energy amount, the magnitude of the mechanical braking force by the braking force generation mechanism is reduced and the regeneration of the electric force generation mechanism is reduced. A braking force control apparatus for a vehicle, wherein the electromagnetic braking force according to a state is increased or the operation of the electric force generation mechanism according to the power running state is decreased . In the vehicle braking force control device according to claim 1 ,
The braking control means includes
When the amount of inflowing electric energy is in a state where the amount of inflow electrical energy can be increased, the magnitude of the mechanical braking force by the braking force generation mechanism is increased in advance to operate the electric force generation mechanism mainly in the power running state. A braking force control device for a vehicle. In the vehicle braking force control device according to claim 2 ,
The situation where the inflow electric energy amount can increase is at least:
A situation in which the distance to a front obstacle existing in front of the vehicle decreases as the vehicle travels, a situation in which the vehicle speed decreases as the vehicle travels, and the operating speed of the braking operation means by the driver increases. The vehicle braking force control apparatus according to any one of the following: a situation, a situation where the magnitude of the target braking force is large, and a situation where the rate of change of the target braking force is large. In the vehicle braking force control device according to claim 3 ,
The braking control means includes
According to a function using at least one of the distance to the front obstacle, the vehicle speed of the vehicle, the operation speed of the braking operation means, the magnitude of the target braking force, and the rate of change of the target braking force. A braking force control apparatus for a vehicle, wherein a ratio between the mechanical braking force by a power generation mechanism and the electromagnetic braking force or the electromagnetic driving force by the electric force generation mechanism is determined. In the vehicle braking force control device according to any one of claims 1 to 4 ,
The braking control means includes
Determining whether the wheels tend to lock based on the road surface conditions on which the vehicle travels,
When determining that the wheel tends to lock, controlling the magnitude of the mechanical braking force by the braking force generation mechanism while maintaining a balance between the inflow electric energy amount and the outflow electric energy amount. A braking force control device for a vehicle. In the vehicle braking force control apparatus according to any one of claims 1 to 5 ,
The braking control means includes
A vehicle that controls the magnitude of the mechanical braking force by the braking force generation mechanism while maintaining a balance between the inflowing electric energy amount and the outflowing electric energy amount for a plurality of two or more wheels. Braking force control device. In the vehicle braking force control device according to claim 6 ,
The braking control means includes
The operation of the regenerative state of the electric force generation mechanism corresponding to some of the plurality of wheels is increased, and the electric force generation mechanism corresponding to the other wheel of the plurality of wheels is increased. Increase the operation due to the power running state,
A braking force control device for a vehicle, which controls the magnitude of the mechanical braking force by the braking force generation mechanism while maintaining a balance between the inflow electric energy amount and the outflow electric energy amount.

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